BENDING MACHINE AND BENDING METHOD

Abstract

 A bending machine (1) includes hydraulic cylinders (9L, 9R) capable of adjusting an inclination state showing an inclination to the left and right of an upper table (7), eccentric shaft units (19L, 19R) configured to curve a part of a lower table (5), and a control device (30). The control device (30) sets an inclination state of the upper table (7) and also sets a curved state of the lower table (5) to conform to the inclination state of the upper table (7) in order to carry out partial bending to pressurize a limited pressurized range compared to a pressurized range in which a workpiece (W) is pressurized by using entire areas of an upper tool (8) and a lower tool (6) in a lateral direction (X). The control device (30) changes a combination of the inclination state of the upper table (7) and the curved state of the lower table (5) and repeats the partial bending while causing a transition of the limited pressurized range in order to carry out entire area bending to pressurize the workpiece (W) over an entire area in the lateral direction (X).

Description

Technical Field

[0001] The present disclosure relates to a bending machine and a bending method.

Background Art

[0002] There is known a bending machine that carries out bending of a plate-shaped workpiece by moving an upper table relative to a lower table so as to pressurize the workpiece between an upper tool and a lower tool. When the bending is carried out, a pressure reaction force is applied to the upper table and the lower table through the workpiece sandwiched between the upper tool and the lower tool. This pressure reaction force generates deflection deformation in the upper table and the lower table, thereby lowering integrated uniform accuracy of the workpiece. The integrated uniform accuracy refers to the accuracy of a bending angle of the workpiece in a direction along a bending line of the workpiece.

[0003] For example, Patent Literature 1 proposes a bending machine that includes, in the center of a lower table, a crowning mechanism for correcting deflection of the lower table, in addition to left and right elevating mechanisms for elevating and lowering the upper table. According to this bending machine, it is possible to improve the integrated uniform accuracy of the workpiece by curving a center part of the lower table upward into a convex shape with the crowning mechanism so as to offset the deflection of the lower table.

Citation List

Patent Literature

[0004] Patent Literature 1: Japanese Patent Application Laid-Open Publication No. 5-329549

Summary

[0005] However, depending on the type of the bending process, such as a bending of a workpiece including a long bending line that extends over an entire area of a table, sufficient integrated uniform accuracy may not be obtained over an entire area of the workpiece in a lateral direction.

[0006] A bending machine according to one aspect of the present disclosure includes a movable table to which a first tool is attached along a lateral direction, and a fixed table arranged to be opposed to the movable table in a vertical direction and to which a second tool is attached along the lateral direction, the movable table being moved in the vertical direction to pressurize a workpiece between the first tool and the second tool in order to carry out bending of the workpiece, the bending machine including an elevating mechanism configured to move the movable table in the vertical direction and capable of adjusting an inclination state showing an inclination to left and right of the movable table, a crowning mechanism configured to curve a part of the fixed table, and a control device configured to control the elevating mechanism and the crowning mechanism, in which the control device sets the inclination state of the movable table and also sets a curved state of the fixed table to conform to the inclination state of the movable table in order in order to carry out partial bending to pressurize a limited pressurized range compared to a pressurized range in which the workpiece is pressurized by using entire areas of the first tool and the second tool in the lateral direction. Further, the control device changes a combination of the inclination state of the movable table and the curved state of the fixed table and repeats the partial bending while causing a transition of the limited pressurized range in order to carry out entire area bending to pressurize the workpiece over an entire area in the lateral direction.

[0007] With this configuration, an entire area of a bending line of the workpiece is not pressurized at once but the limited pressurized range is pressurized. At this time, by inclining the movable table in accordance with the pressurized range and by curving the fixed table so as to conform to this inclination state, it is possible to suppress deflection of the tables in the pressurized range. Since the deflection of the tables in the pressurized range is suppressed, a distance between a distal end of the first tool and a distal end of the second tool can be maintained constant at the time of pressurization. As a result, bending angles in an entire area of the pressurized ranges pressurized by the tools can be made uniform. In addition, by repeating the partial bending while causing a transition of the pressurized range, it is possible to pressurize the workpiece over the entire area in the lateral direction. At this time, since the bending angle is guaranteed in each of the pressurized ranges in which the partial bending is carried out, the bending angles in the entire area of the workpiece in the lateral direction can be made uniform by the entire area bending.

[0008] According to the one aspect of the present disclosure, it is possible to obtain sufficient integrated uniform accuracy over the entire area of the workpiece in the lateral direction.

Brief Description of Drawings

[0009] 

[Figure 1] Figure 1 is an explanatory diagram schematically showing a configuration of a bending machine according to the present embodiment.

[Figure 2] Figure 2 is an explanatory diagram showing a first step of a bending operation by the bending machine.

[Figure 3] Figure 3 is an explanatory diagram showing a second step of the bending operation by the bending machine.

[Figure 4] Figure 4 is an explanatory diagram showing a third step of the bending operation by the bending machine.

[Figure 5] Figure 5 is an explanatory diagram showing a fourth step of the bending operation by the bending machine.

[Figure 6] Figure 6 is an explanatory diagram showing a fifth step of the bending operation by the bending machine.

[Figure 7] Figure 7 is an explanatory diagram showing a sixth step of the bending operation by the bending machine.

[Figure 8] Figure 8 is an explanatory diagram showing a seventh step of the bending operation by the bending machine.

[Figure 9] Figure 9 is an explanatory diagram showing an eighth step of the bending operation by the bending machine.

[Figure 10] Figure 10 is an explanatory diagram showing a ninth step of the bending operation by the bending machine.

[Figure 11] Figure 11 is an explanatory diagram showing a tenth step of the bending operation by the bending machine.

[Figure 12] Figure 12 is an explanatory diagram showing an eleventh step of the bending operation by the bending machine.

[Figure 13] Figure 13 is an explanatory diagram showing angle measurement points in a workpiece.

[Figure 14] Figure 14 is a diagram showing an input screen to which angle measurement results are input.

[Figure 15] Figure 15 is an explanatory diagram showing an example of the workpiece to be processed.

[Figure 16] Figure 16 is an explanatory diagram showing an operation of pressurizing the workpiece alternately to the left and right.

[Figure 17] Figure 17 is an explanatory diagram showing the operation of pressurizing the workpiece alternately to the left and right.

Description of Embodiment

[0010] A bending machine and a bending method according to the present embodiment will be described below with reference to the drawings.

[0011] Figure 1 is an explanatory diagram schematically showing a configuration of the bending machine according to the present embodiment. In the following description, a lateral direction X, a front-rear direction Y, and a vertical direction Z are used to define the bending machine. The lateral direction X and the front-rear direction Y correspond to two directions that are orthogonal in the horizontal direction, and the vertical direction Z corresponds to the perpendicular direction. However, these directions are only used for convenience in order to describe the bending machine in the present embodiment.

[0012] A bending machine 1 according to the present embodiment includes an upper table 7 (an example of a movable table) to which an upper tool 8 (an example of a first tool) is attached along the lateral direction X, and a lower table 5 (an example of a fixed table) arranged to be opposed to the upper table in the vertical direction Z and to which a lower tool 6 is attached along the lateral direction X. The bending machine 1 carries out bending of a workpiece by moving the upper table 7 in the vertical direction Z and pressurizing the workpiece between the upper tool 8 and the lower tool 6.

[0013] The bending machine 1 includes hydraulic cylinders 9L and 9R (an example of an elevating mechanism) configured to move the upper table 7 in the vertical direction Z and capable of adjusting an inclination state showing an inclination to the left and right of the upper table, eccentric shaft units 19L and 19R (an example of a crowning mechanism) configured to curve a part of the lower table 5, and a control device 30 configured to control the hydraulic cylinders 9L and 9R and the eccentric shaft units 19L and 19R. The control device 30 sets the inclination state of the upper table 7 and also sets a curved state of the lower table 5 to conform to the inclination state of the upper table in order to carry out partial bending to pressurize a limited pressurized range compared to a pressurized range when the workpiece is pressurized by using entire areas of the upper tool 8 and the lower tool 6 in the lateral direction X. The control device 30 changes a combination of the inclination state of the upper table 7 and the curved state of the lower table 5 and repeats the partial bending while causing a transition of the limited pressurized range in order to carry out entire area bending to pressurize the workpiece W over an entire area in the lateral direction X.

[0014] A detailed configuration of the bending machine 1 will be described below. The bending machine 1 is a processing machine that carries out the bending to a plate-shaped workpiece such as a sheet metal, for example. The bending machine 1 is, for example, a press brake, and carries out the bending to the workpiece by cooperation between the upper tool 8 such as a punch and the lower tool 6 such as a die.

[0015] The bending machine 1 includes the lower table 5, the upper table 7, the left and right hydraulic cylinders 9L and 9R, the left and right eccentric shaft units 19L and 19R, and the control device 30.

[0016] The bending machine 1 includes left and right side frames 3L and 3R provided so as to be separated in the lateral direction X. The upper table 7 extends in the lateral direction X and is supported by front side upper portions of the side frames 3L and 3R. The upper table 7 is configured to be movable in the vertical direction Z. The lower table 5 extends in the lateral direction X and is supported by front side lower portions of the side frames 3L and 3R.

[0017]  An upper tool holder that installably and removably holds the upper tool 8 is provided on a lower side of the upper table 7. A holder groove for a base portion of the upper tool 8 to be inserted into is formed along the lateral direction X in the upper tool holder. The upper tool holder includes a clamping mechanism that fixes the upper tool 8 to the upper table 7.

[0018] A lower tool holder that installably and removably holds the lower tool 6 is provided on an upper side of the lower table 5. A holder groove for a base portion of the lower tool 6 to be inserted into is formed along the lateral direction X in the lower tool holder. The lower tool holder includes a clamping mechanism that fixes the lower tool 6 to the lower table 5.

[0019] The left and right hydraulic cylinders 9L and 9R are provided on left and right upper portions of the side frames 3L and 3R, respectively. The left and right hydraulic cylinders 9L and 9R function as the elevating mechanism that moves the upper table 7 in the vertical direction Z. The left and right hydraulic cylinders 9L and 9R can be controlled independently from each other. By independently controlling the left and right hydraulic cylinders 9L and 9R, it is possible to adjust the inclination state showing the inclination to the left and right of the upper table 7. It should be noted that the elevating mechanism is not limited to the configuration that uses the hydraulic cylinders 9L and 9R arranged on the left and right, and may be configured by electric motors arranged on the left and right.

[0020] The inclination state of the upper table 7 includes an inclination state inclined downward to a left and an inclination state inclined downward to a right. The inclination state inclined downward to the left refers to an inclination state in which a left side of the upper table 7 is closer to the lower table 5 than a right side thereof, and in the present embodiment, an inclination state in which the left side of the upper table 7 is more inclined downward than the right side thereof. On the other hand, the inclination state inclined downward to the right refers to an inclination state in which the right side of the upper table 7 is closer to the lower table 5 than the left side thereof, and in the present embodiment, an inclination state in which the right side of the upper table 7 is more inclined downward than the left side thereof. It should be noted that any inclination state inclined downward to the left can be used as long as the left side of the upper table 7 is more inclined downward than the right side thereof, and an inclination degree (angle) of the upper table 7 with respect to the horizon can be arbitrarily set within a movable range of the upper table 7. This applies to the inclination state inclined downward to the right.

[0021] Further, the inclination state of the upper table 7 includes not only the state of being inclined either to the left or right but also a basic posture of the upper table 7. The basic posture of the upper table 7 refers to a state in which a height of the left side of the upper table 7 and a height of the right side thereof are the same and the upper table 7 is horizontal to the left and right.

[0022] A front plate 11 and a rear plate 13 are provided to a front side and a rear side of the lower table 5, respectively. The front plate 11 and the rear plate 13 are integrally attached to the lower table 5 via left and right pivot pins 15L and 15R that penetrate in the front-rear direction Y.

[0023] Left and right through holes 17L and 17R that penetrate through the front plate 11, the lower table 5, and the rear plate 13 in the front-rear direction Y are provided at symmetrical positions to the left and right with respect to a center position of the lower table 5 in the lateral direction X. Inside the left and right through holes 17L and 17R, the left and right eccentric shaft units 19L and 19R are provided. The left eccentric shaft unit 19L is arranged at a position closer to the center position of the lower table 5 than the left hydraulic cylinder 9L when viewed in the lateral direction X. In the same manner, the right eccentric shaft unit 19R is arranged at a position closer to the center position of the lower table 5 than the right hydraulic cylinder 9R when viewed in the lateral direction X.

[0024] The eccentric shaft units 19L and 19R are fixed to the front plate 11 and the rear plate 13. The eccentric shaft units 19L and 19R can press the lower table 5 upward against the front plate 11 and the rear plate 13 by rotating eccentric shafts. By pressing the lower table 5 upward, the eccentric shaft units 19L and 19R function as the crowning mechanism that curve the part of the lower table 5 in an upward direction into a convex shape. It should be noted that the crowning mechanism is not limited to the configuration that uses the eccentric shaft units 19L and 19R arranged to the left and right, and may be configured with the hydraulic cylinders arranged on the left and right.

[0025] The left and right eccentric shaft units 19L and 19R can be controlled independently. By independently controlling the left and right eccentric shaft units 19L and 19R, it is possible to adjust the curved state of the lower table 5. Adjusting the curved state includes adjusting a position at which the lower table 5 is curved such as a left side, a center, and a right side, a shape of the curving, a degree of the curving, and the like. In other words, by independently controlling the left and right eccentric shaft units 19L and 19R, it is possible to make the curved shape of the lower table 5 into a symmetrical shape or into an asymmetrical shape.

[0026] The control device 30 is, for example, a computer such as an NC (Numerical Control) device. The computer mainly includes a hardware processor such as a CPU (Central Processing Unit), a memory, and various interfaces. The memory and the various interfaces are connected to the hardware processor via buses. A predetermined computer program is installed in the computer. The hardware processor executes the computer program, so that the computer executes a function provided to the control device 30.

[0027] The control device 30 controls an operation of the bending machine 1. Specifically, the control device 30 controls the left and right hydraulic cylinders 9L and 9R and the left and right eccentric shaft units 19L and 19R. The control device 30 can control a movement of the upper table 7 in the vertical direction Z, the inclination state of the upper table 7, and the curved state of the lower table 5 by controlling the left and right hydraulic cylinders 9L and 9R and the left and right eccentric shaft units 19L and 19R.

[0028] In the bending machine 1 having such a configuration, the plate-shaped workpiece is positioned on the lower tool 6 mounted on the lower table 5. The control device 30 lowers the upper table 7 toward the lower table 5. As a result, the workpiece is pressurized between the upper tool 8 and the lower tool 6 so that the workpiece is bent at a desired target bending angle by cooperation between the upper tool 8 and the lower tool 6.

[0029] As one of the features of the present embodiment, the control device 30 not only sets the inclination state of the upper table 7 and but also sets the curved state of the lower table 5 so as to conform to the inclination state of the upper table 7. Then, the control device 30 carries out the partial bending to pressurize the limited pressurized range compared to the pressurized range when the workpiece is pressurized by using the entire areas of the upper tool 8 and the lower tool 6 in the lateral direction X.

[0030] Further, the control device 30 changes the combination of the inclination state of the upper table 7 and the curved state of the lower table 5 and repeats the partial bending while causing a transition of the limited pressurized range in order to carry out the entire area bending to pressurize the workpiece W over the entire area in the lateral direction X. Then, the control device 30 bends the workpiece step by step until the target bending angle is reached by repeating the entire area bending a plurality of times.

[0031] The bending method according to the present embodiment, that is, a bending operation by the bending machine 1 will be described below.

[0032] Figure 2 is an explanatory diagram showing a first step of the bending operation by the bending machine. At a start of the bending operation, the upper table 7 is positioned at a top dead center Ht, and the inclination state thereof is set to be horizontal to the left and right. The left and right hydraulic cylinders 9L and 9R can move the upper table 7 along the vertical direction Z in a range from the top dead center Ht to a bottom dead center Hb. The top dead center Ht is a point at which the upper table 7 is separated from the lower table 5 by a predetermined distance, and the bottom dead center Hb is a point at which the upper table 7 comes closest to the lower table 5.

[0033]  As shown in Figure 2, the control device 30 moves the upper table 7 downward while maintaining the horizontally inclination state thereof.

[0034] Figure 3 is an explanatory diagram showing a second step of the bending operation by the bending machine. When the upper table 7 reaches a reference position H1, the control device 30 sets the upper table 7 to the inclination state inclined downward to the left. The upper table 7 is changed to the inclination state inclined downward to the left in such a way that, for example, the left hydraulic cylinder 9L is lowered and the right hydraulic cylinder 9R is elevated.

[0035] The reference position H1 is set at a position above the bottom dead center Hb from a viewpoint of setting the inclination state of the upper table 7 before the upper table 7 reaches the bottom dead center Hb. As the reference position H1, (1) a speed changing position at which a lowering speed of the upper table 7 is changed, (2) a position at which a distal end of the upper tool 8 comes into contact with the workpiece W (a so-called pinching point), and (3) a position at which the workpiece W is pressurized between the upper tool 8 and the lower tool 6 so that a bending angle of the workpiece W reaches a predetermined reference angle, and the like. The reference angle is an angle for determining that the workpiece W has been bent by a predetermined amount, and is set as an angle larger than the target bending angle.

[0036] Figure 4 is an explanatory diagram showing a third step of the bending operation by the bending machine. The control device 30 lowers the upper table 7 while maintaining the inclination state thereof inclined downward to the left so as to pressurize the workpiece W between the upper table 7 and the lower table 5. Since the upper table 7 is set to the inclination state inclined downward to the left, an area on the left side of the upper tool 8 first comes into contact with an area on the left side of the workpiece W. Further, areas in the center and on the right side of the upper tool 8 are separated from areas in the center and on the right side of the workpiece W. As a result, only a limited pressurized range (hereinafter referred to as a "left pressurized range") La positioned on the left side of the workpiece W is locally pressurized. The left pressurized range La is a range, which is narrower than the pressurized range (a bending range in the lateral direction X in the workpiece W) in which the workpiece W is pressurized by using the entire areas of the upper tool 8 and the lower tool 6 in the lateral direction X. For example, it is assumed that the left pressurized range La is a range about 1/3 of a length of the entire area of the workpiece W in the lateral direction X (a total length of a bending line).

[0037] Figure 5 is an explanatory diagram showing a fourth step of the bending operation by the bending machine. Since the upper table 7 is inclined downward to the left, an area on the left side of the left pressurized range La has a steeper bending angle than an area on the right side thereof. Therefore, in order to eliminate variation in the bending angle within the left pressurized range La, the control device 30 sets the curved state of the lower table 5 so as to conform to the inclination state of the upper table 7. Specifically, the control device 30 sets the curved state of the lower table 5 such that the left side of the lower table 5 conforms to the inclination state of the upper table 7 inclined downward to the left. For example, the control device 30 curves the left side from the center of the lower table 5 upward into the convex shape. However, the curved state of the lower table 5 is not limited to this as long as the left side of the lower table 5 conforms to the inclination state of the upper table 7 inclined downward to the left. The control device 30 controls one or both of the left and right eccentric shaft units 19L and 19R to set the curved state of the lower table 5.

[0038]  It should be noted that in the present embodiment, the control device 30 sets the curved state of the lower table 5 after the upper table 7 pressurizes the workpiece W. However, the control device 30 may set the curved state of the lower table 5 in advance before the upper table 7 pressurizes the workpiece W. However, when the curved state of the lower table 5 is set in advance, there is a possibility that misalignment of the workpiece W may be generated due to the curving of the lower table 5. Therefore, it is preferable to set the curved state of the lower table 5 in a state in which the upper table 7 pressurizes the workpiece W so that the workpiece W is fixed.

[0039] Figure 6 is an explanatory diagram showing a fifth step of the bending operation by the bending machine. If the lowering of the upper table 7 is continued so that the upper table 7 is lowered to the bottom dead center Hb, not only the left side of the workpiece W but also the entire area of the workpiece W in the lateral direction X are pressurized. Therefore, the control device 30 elevates the upper table 7 before the entire area of the workpiece W in the lateral direction X is pressurized, that is, before the upper table 7 reaches the bottom dead center Hb. As a result, a pressure applied to the workpiece W is released.

[0040]  As the pressure is released, the control device 30 cancels the curved state of the lower table 5 and adjusts the entire area of the lower table 5 in the lateral direction X to be flat.

[0041] When the upper table 7 is elevated as the pressure is released, there is a possibility that the workpiece W may be misaligned if the upper table 7 is elevated to a large extent. Therefore, it is preferable that the control device 30 elevates the upper table 7 up to, as an upper limit, a position at which spring back of the workpiece W ends. By elevating the upper table 7 within such a range, it is possible to maintain a state in which the workpiece W and the upper tool 8 are in contact with each other, which makes it possible to suppress the misalignment of the workpiece W.

[0042] The position at which the spring back of the workpiece W ends refers to a position at which the upper table 7 is elevated to gradually release the pressure against the workpiece W so that the pressure becomes almost zero. The position at which the spring back ends can be determined by (1) known information calculated from processing conditions, (2) pressure values of the left and right hydraulic cylinders 9L and 9R, and (3) a measured value of the bending angle of the workpiece W obtained by an angle sensor or the like, and the like.

[0043] Further, when the upper table 7 is elevated, the control device 30 elevates the upper table 7 in parallel while maintaining the inclination state of the upper table 7 at the time of pressurization, that is, the inclination state inclined downward to the left. By elevating the upper table 7 in parallel while maintaining the inclination state thereof, it is possible to evenly release a load applied to the left pressurized range La. Therefore, it is possible to improve integrated uniform accuracy in the left pressurized range La.

[0044] Figure 7 is an explanatory diagram showing a sixth step of the bending operation by the bending machine. When the pressurization to and the pressure release from the left pressurized range La are ended, the control device 30 sets the upper table 7 to the inclination state that is horizontal to the left and right. The upper table 7 is changed from the inclination state inclined downward to the left to the inclination state that is horizontal to the left and right in such a way that, for example, the left hydraulic cylinder 9L is elevated and the right hydraulic cylinder 9R is lowered.

[0045] Figure 8 is an explanatory diagram showing a seventh step of the bending operation by the bending machine. The control device 30 lowers the upper table 7 while maintaining the inclination state thereof, which is horizontal to the left and right, so as to pressurize the workpiece W between the upper table 7 and the lower table 5.

[0046] Figure 9 is an explanatory diagram showing an eighth step of the bending operation by the bending machine. If the workpiece W is pressurized in a state in which the upper table 7 is simply lowered, the entire area of the workpiece W in the lateral direction X is pressurized. Therefore, the control device 30 sets the curving state of the lower table 5 such that a limited pressurized range (hereinafter referred to as a "center pressurized range") Lb positioned in the center of the workpiece W is locally pressurized as the upper table 7 is pressurized. Specifically, the control device 30 sets the curved state of the lower table 5 such that the center of the lower table 5 is curved upward into the convex shape. The control device 30 controls one or both of the left and right eccentric shaft units 19L and 19R to set the curved state of the lower table 5.

[0047] Although the upper table 7 is set in the inclination state that is horizontal to the left and right, the center of the lower table 5 is curved upward. Therefore, the area in the center of the upper tool 8 first comes into contact with the area in the center of the workpiece W. Further, the areas on the left side and on the right side of the upper tool 8 are separated from the areas on the left side and on the right side of the workpiece W. As a result, only the center pressurized range Lb is locally pressurized. The center pressurized range Lb is a range, which is narrower than the pressurized range (the bending range in the workpiece W in the lateral direction X) in which the workpiece W is pressurized by using the entire areas of the upper tool 8 and the lower tool 6 in the lateral direction X. For example, it is assumed that the limited pressurized range Lb is about 1/3 of the length of the entire area of the workpiece W in the lateral direction X (the total length of the bending line).

[0048] Further, in order to eliminate the variation in the bending angle within the center pressurized range Lb, the control device 30 sets the curved state of the lower table 5 so as to conform to the inclination state of the upper table 7, such as into a trapezoidal shape with an upper base being flat.

[0049] Figure 10 is an explanatory diagram showing a ninth step of the bending operation by the bending machine. If the lowering of the upper table 7 is continued so that the upper table 7 is lowered to the bottom dead center Hb, not only the center of the workpiece W but also the entire area of the workpiece W in the lateral direction X are pressurized. Therefore, the control device 30 elevates the upper table 7 before the entire area of the workpiece W in the lateral direction X is pressurized, that is, before the upper table 7 reaches the bottom dead center Hb. As a result, the pressure applied to the workpiece W is released. The method of elevating the upper table 7 to release the pressure is as described above.

[0050] As the pressure is released, the control device 30 cancels the curved state of the lower table 5 and adjusts the entire area of the lower table 5 in the lateral direction X to be flat.

[0051] Figure 11 is an explanatory diagram showing a tenth step of the bending operation by the bending machine. The control device 30 sets the upper table 7 to the inclination state inclined downward to the right. The upper table 7 is changed to the inclination state inclined downward to the right in such a way that, for example, the right hydraulic cylinder 9R is lowered and the left hydraulic cylinder 9L is elevated.

[0052] Figure 12 is an explanatory diagram showing an eleventh step of the bending operation by the bending machine. The control device 30 lowers the upper table 7 while maintaining the inclination state thereof inclined downward to the right so as to pressurize the workpiece W between the upper table 7 and the lower table 5. Since the upper table 7 is set to the inclination state inclined downward to the right, the area on the right side of the upper tool 8 first comes into contact with the area on the right side of the workpiece W. Further, the areas on the left side and in the center of the upper tool 8 are separated from the areas on the left side and in the center of the workpiece W. As a result, only a limited pressurized range (hereinafter referred to as a "right pressurized range") Lc positioned on the right side of the workpiece W is locally pressurized. The right pressurized range Lc is a range, which is narrower than the pressurized range (the bending range in the lateral direction X in the workpiece W) in which the workpiece W is pressurized by using the entire areas of the upper tool 8 and the lower tool 6 in the lateral direction X. For example, it is assumed that the right pressurized range Lc is a range about 1/3 of the length of the entire area of the workpiece W in the lateral direction X (the total length of the bending line).

[0053] Further, in order to eliminate the variation in the bending angle within the right pressurized range Lc, the control device 30 sets the curved state of the lower table 5 so as to conform to the inclination state of the upper table 7. Specifically, the control device 30 sets the curved state of the lower table 5 such that the right side of the lower table 5 corresponding to the limited pressurized range Lc conforms to the inclination state of the upper table 7 inclined downward to the right. For example, the control device 30 curves the right side from the center of the lower table 5 upward into the convex shape. However, the curved state of the lower table 5 is not limited to this as long as the right side of the lower table 5 conforms to the inclination state of the upper table 7 inclined downward to the right. The control device 30 controls one or both of the left and right eccentric shaft units 19L and 19R to set the curved state of the lower table 5.

[0054] In this manner, the control device 30 changes the combination of the inclination state of the upper table 7 and the curved state of the lower table 5, and repeats a pressurizing operation (the partial bending) to the three pressurized ranges La, Lb, and Lc. As a result, the control device 30 carries out the entire area bending in which the entire area of the workpiece W in the lateral direction X is pressurized.

[0055] The control device 30 repeats the entire area bending a plurality of times to bend the workpiece W step by step until the target bending angle is reached. Then, when the workpiece W is bent to the target bending angle, the bending to the workpiece W is ended.

[0056] Next, referring to Figures 13 and 14, a method of determining outputs of the left and right hydraulic cylinders 9L and 9R and outputs of the left and right eccentric shaft units 19L and 19R when the pressurized ranges La, Lb, and Lc are pressurized will be described. Figure 13 is an explanatory diagram showing angle measurement points in the workpiece. Figure 14 is a diagram showing an input screen to which angle measurement results are input.

[0057] The outputs of the left and right hydraulic cylinders 9L and 9R herein are control parameters corresponding to a pushing amount of the upper table 7 and an inclination amount of the upper table 7. The pushing amount of the upper table 7 refers to an amount of lowering the upper table 7 from the pinching point, which is required to obtain a predetermined bending angle. The outputs of the left and right eccentric shaft units 19L and 19R are control parameters corresponding to a curving position, the curved shape, and a magnitude of the curving of the lower table 5.

[0058] First, the control device 30 tentatively determines the outputs of the left and right hydraulic cylinders 9L and 9R and the outputs of the left and right eccentric shaft units 19L and 19R for each of the pressurized range La, Lb, and Lc from bending conditions, that is, a thickness, a material, and a length of the bending line of the workpiece W.

[0059] An operator prepares the workpiece W for a trial bending. Under the control of the control device 30, the combination of the inclination state of the upper table 7 and the curved state of the lower table 5 is changed for each of the pressurized ranges La, Lb, and Lc so as to carry out the pressurizing operation (the partial bending) to each of the pressurized ranges La, Lb, and Lc. As a result, the entire area of the workpiece W in the lateral direction X (the entire area of the bending line) is pressurized (the entire area bending).

[0060] Then, as shown in Figure 13, the bending angle of the workpiece W is measured at each of angle measurement points M1 to M4. The angle measurement point M1 is a point at a left end of the workpiece W, that is, a point at a left end of the left pressurized range La. The angle measurement point M2 is a point at a right end of the left pressurized range La and a point at a left end of the center pressurized range Lb. The angle measurement point M3 is a point at a right end of the center pressurized range Lb and a point at a left end of the left pressurized range Lc. The angle measurement point M4 is a point at a right end of the workpiece W, that is, a point at a right end of the right pressurized range Lc. In this manner, the four angle measurement points M1 to M4 are positioned at boundaries of the respective pressurized ranges La, Lb, and Lc.

[0061] Measurement of the bending angle at each of the angle measurement points M1 to M4 can be manually carried out by the operator himself or herself by using the angle sensor. Alternatively, the measurement of the bending angle at each of the angle measurement points M1 to M4 may be automatically carried out as the operator carries out a predetermined operation to an operation panel 35 (see Figure 14) so that the control device 30 actuates the angle sensor mounted on the bending machine 1.

[0062] When the operator manually measures the bending angle, the operator inputs a measured value of the bending angle at each of the angle measurement points M1 to M4 to the operation panel so that the control device 30 can obtain the information. Further, when the control device 30 automatically measures the bending angle, the control device 30 can directly obtain the measured value of the bending angle at each of the angle measurement points M1 to M4 from the angle sensor.

[0063]  In this manner, the bending angle measured at each of the angle measurement points M1 to M4 is input to the control device 30. As shown in Figure 14, the control device 30 displays the measured value of the bending angle at each of the angle measurement points M1 to M4 on a predetermined display screen 36 of the operation panel 35. The display screen 36 includes four display items 36a to 36d each for displaying the measured value of the bending angle at each of the angle measurement points M1 to M4.

[0064] The control device 30 carries out a necessary calculation for each of the three pressurized ranges La, Lb, and Lc based on the bending angle measured at each of the angle measurement points M1 to M4.

[0065] Specifically, the control device 30 uses the bending angles obtained from the three angle measurement points M1 to M3 to correct the outputs of the left and right hydraulic cylinders 9L and 9R and the outputs of the left and right eccentric shaft units 19L and 19R when the left pressurized range La is pressurized. At this time, the control device 30 corrects the outputs of the left and right hydraulic cylinders 9L and 9R based on the angle measurement points M1 and M3, and corrects the outputs of the left and right eccentric shaft units 19L and 19R based on the angle measurement point M2.

[0066] In the same manner, the control device 30 uses the bending angles obtained from the four angle measurement points M1 to M4 to correct the outputs of the left and right hydraulic cylinders 9L and 9R and the outputs of the left and right eccentric shaft units 19L and 19R when the center pressurized range Lb is pressurized. At this time, the control device 30 corrects the output of the left hydraulic cylinder 9L based on the angle measurement point M1, and corrects the output of the right hydraulic cylinder 9R based on the angle measurement point M4. The control device 30 corrects the output of the left eccentric shaft unit 19L based on the angle measurement point M2, and corrects the output of the right eccentric shaft unit 19R based on the angle measurement point M3.

[0067] In addition, the control device 30 uses the three bending angles at the angle measurement points M2 to M4 to control the outputs of the left and right hydraulic cylinders 9L and 9R and the outputs of the left and right eccentric shaft units 19L and 19R when the right pressurized range Lc is pressurized. At this time, the control device 30 corrects the outputs of the left and right hydraulic cylinders 9L and 9R based on the angle measurement points M2 and M4, and corrects the outputs of the left and right eccentric shaft units 19L and 19R based on the angle measurement point M3.

[0068] When the correction is carried out in this manner, the control device 30 controls the left and right hydraulic cylinders 9L and 9R and the left and right eccentric shaft units 19L and 19R in accordance with the corrected outputs. As a result, it is possible to pressurize the workpiece W with appropriate outputs.

[0069] It should be noted that in the above description, prior to the angle measurement, the pressurizing operation (the partial bending) is repeated to the three pressurized ranges La, Lb, and Lc of the workpiece W for the trial bending so that the entire area of the workpiece W in the lateral direction X is pressurized (the entire area bending). However, the entire area of the workpiece W may be pressurized at once while the upper table 7 is kept in the inclination state that is horizontal to the left and right so as to measure the bending angle of the workpiece W at that time.

[0070] As described above, in the bending machine 1 of the present embodiment, the control device 30 sets the inclination state of the upper table 7 and also sets the curved state of the lower table 5 to conform to the inclination state of the upper table 7 in order to carry out the partial bending to pressurize the pressurized ranges La, Lb, and Lc that are limited compared to the pressurized range in which the workpiece W is pressurized by using the entire areas of the upper tool 8 and the lower tool 6 in the lateral direction X. Then, the control device 30 changes the combination of the inclination state of the upper table 7 and the curved state of the lower table 5 and repeats the partial bending while causing a transition among the limited pressurized ranges La, Lb, and Lc in order to carry out the entire area bending to pressurize the workpiece W over the entire area in the lateral direction X.

[0071] According to the bending machine 1 of the present embodiment, a first effect as shown in the following is achieved. In other words, according to the bending machine 1 of the present embodiment, the entire area of the workpiece W (the bending line of the workpiece W) is not pressurized at once, but pressurization is performed for each of the limited pressurized ranges La, Lb, and Lc. At this time, by inclining the upper table 7 in accordance with the pressurized ranges La, Lb, and Lc, and by curving the lower table 5 so as to conform to this inclination state, it is possible to suppress deflection of the table in the pressurized ranges La, Lb, and Lc. Since the deflection of the table in the pressurized ranges La, Lb, and Lc is suppressed, a distance between a lower end of the upper tool 8 and an upper end of the lower tool 6 can be maintained constant at the time of the pressurization. As a result, the bending angles in the entire area of the pressurized ranges La, Lb, and Lc pressurized by the upper tool 8 and the lower tool 6 can be made uniform, making it possible to improve the integrated uniform accuracy throughout the pressurized ranges La, Lb, and Lc.

[0072] For example, even when the inclination state of the upper table 7 is changed for each of the pressurized ranges La, Lb, and Lc, if the curved state of the lower table 5 is fixed, the curved state of the lower table 5 may not conform to the inclination state of the upper table 7. In the same manner, even when the curved state of the lower table 5 is changed for each of the pressurized ranges La, Lb, and Lc, if the inclination state of the upper table 7 is fixed, the curved state of the lower table 5 may not conform to the inclination state of the upper table 7. In this case, the variation occurs in the distance between the lower end of the upper tool 8 and the upper end of the lower tool 6. Therefore, as shown in the present embodiment, it is essential to set the inclination state of the upper table and the curved state of the lower table 5 that conforms to the inclination state in accordance with the pressurized ranges La, Lb, and Lc.

[0073]  Further, by repeating the partial bending while causing a transition among the pressurized ranges La, Lb, and Lc, it is possible to pressurize the workpiece W over the entire area in the lateral direction X. At this time, since the bending angle is guaranteed in each of the pressurized ranges La, Lb, and Lc in which the partial bending is carried out, the bending angles in the entire area of the workpiece W in the lateral direction X can be made uniform by the entire area bending. As a result, it is possible to obtain sufficient integrated uniform accuracy over the entire area of the workpiece W in the lateral direction X.

[0074] In addition, according to the bending machine 1 of the present embodiment, a second effect as shown in the following is further achieved. First, a bending method will be considered in which the upper table 7 is lowered while remaining in the inclination state that is horizontal to the left and right, and the workpiece W is pressurized by using the entire areas of the upper tool 8 and the lower tool 6 in the lateral direction X. In the case of this bending method, the entire area of the workpiece W in the lateral direction X is pressurized by receiving a bending load from the upper table 7. About 1/3 of the load applied from the upper table 7 is applied to an area corresponding to the left pressurized range La shown in Figure 4. In contrast, as shown in the present embodiment, when only the left pressurized range La is locally pressurized, the load applied from the upper table 7 is applied only to the left pressurized range La in a concentrated manner. Therefore, by pressurizing the left pressurized range La in a limited manner, even if the bending load is smaller than the bending load required when the entire area of the workpiece W in the lateral direction X is pressurized, it is possible to apply an equivalent pressure to the workpiece W. In other words, by pressurizing the left pressurized range La, the bending machine 1 can carry out the bending with the bending load that is smaller than the bending load required when the entire area of the workpiece W in the lateral direction X is pressurized.

[0075] In the same manner, as shown in Figure 9, by pressurizing only the center pressurized range Lb in a limited manner, the bending machine 1 can carry out the bending with the bending load that is smaller than the bending load required when the entire area of the workpiece W in the lateral direction X is pressurized. Furthermore, as shown in Figure 12, by pressurizing only the right pressurized range Lc in a limited manner, the bending machine 1 can carry out the bending with the bending load that is smaller than the bending load required when the entire area of the workpiece W in the lateral direction X is pressurized.

[0076] In this manner, by utilizing the inclination state of the upper table 7 and the curved state of the lower table 5, it is possible to locally pressurize the limited pressurized ranges. In this case, the bending load applied from the upper table 7 is applied to the limited pressurized ranges La, Lb, and Lc in a concentrated manner. By pressurizing the limited pressurized ranges La, Lb, and Lc, even if the bending load is smaller than the bending load required for pressurizing the entire area of the workpiece W in the lateral direction X, the equivalent pressure (stress) is applied to the pressurized ranges. In other words, by pressurizing the limited pressurized ranges La, Lb, and Lc, the bending machine 1 can carry out the bending with the bending load that is smaller than the bending load required when the entire area of the workpiece W in the lateral direction X is pressurized. Therefore, it is possible to carry out a desired bending to the workpiece W without using the bending machine 1 having a high pressurization capability.

[0077] Further, as described above, by changing the combination of the inclination state of the upper table 7 and the curved state of the lower table 5, it is possible to cause a transition among the limited pressurized ranges La, Lb, and Lc. As a result, it is possible to appropriately pressurize the entire area in the lateral direction X in the workpiece W without using the bending machine 1 having the high pressurization capability.

[0078] In the bending machine 1 of the present embodiment, the control device 30 repeats the entire area bending a plurality of times to bend the workpiece W step by step to the target bending angle.

[0079] According to this configuration, the bending angle of the workpiece W can be brought close to the target bending angle step by step by bending the workpiece W step by step. As a result, it is possible to more reliably improve the integrated uniform accuracy. In addition, even if the bending load is small, it is possible to bend the workpiece W to the target bending angle by bending the workpiece W step by step. As a result, it is possible to bend the workpiece W to the desired target bending angle without using the bending machine 1 having the high pressurization capability.

[0080] In the bending machine 1 of the present embodiment, the left and right hydraulic cylinders 9L and 9R can move the upper table 7 in the range from the top dead center Ht to the bottom dead center Hb. When the partial bending is carried out, the control device 30 sets the inclination state of the upper table 7 before the upper table 7 reaches the bottom dead center Hb.

[0081] When the entire area of the workpiece W in the lateral direction X is pressurized, the bending load is dispersed over the entire area of the workpiece W, which makes it impossible for the pressure required for the bending to be applied to the workpiece W. In this respect, according to the configuration of the present embodiment, since the inclination state of the upper table 7 is inclined before the upper table 7 reaches the bottom dead center Hb, it is possible to suppress a situation in which the entire area of the workpiece W in the lateral direction X is pressurized at once. Since the workpiece W can be pressurized for each of the pressurized ranges La, Lb, and Lc, it is possible to improve the integrated uniform accuracy throughout the pressurized ranges La, Lb, and Lc. In addition, it is possible to carry out the desired bending in each of the pressurized ranges La, Lb, and Lc without using the bending machine 1 with the high pressurization capability.

[0082] In the bending machine 1 of the present embodiment, the control device 30 pressurizes the workpiece W, and then moves the upper table 7 toward the top dead center Ht in a range in which the upper tool 8 and the workpiece W are in contact with each other by the spring back of the workpiece W, after which the combination of the inclination state of the upper table 7 and the curved state of the lower table 5 is changed.

[0083] According to this configuration, even if the upper table 7 is elevated as the pressure is released, the upper table 7 is elevated only in the range in which the upper tool 8 is in contact with the workpiece W. Therefore, when the combination of the inclination state of the upper table 7 and the curved state of the fixed table is changed, it is possible to suppress the misalignment of the workpiece W as the upper tool 8 presses the workpiece W. As a result, it is possible to carry out the bending of the workpiece W with high accuracy. It is possible to improve the integrated uniform accuracy throughout the pressurized ranges La, Lb, and Lc.

[0084] In the bending machine 1 of the present embodiment, the control device 30 moves the upper table 7 toward the top dead center Ht while maintaining the inclination state thereof when the workpiece W is pressurized.

[0085] According to this configuration, since the upper table 7 is moved while maintaining the inclination state thereof, it is possible to evenly release the loads applied to the pressurized ranges. As a result, it is possible to improve the integrated uniform accuracy of the workpiece W throughout the pressurized ranges La, Lb, and Lc.

[0086] In the bending machine 1 of the present embodiment, the control device 30 curves the left side of the lower table 5 upward in a case of an inclination state in which the left side of the upper table 7 is closer to the lower table 5 than the right side thereof.

[0087] According to this configuration, it is possible to pressurize the area on the left side of the workpiece W with high integrated uniform accuracy.

[0088] In the bending machine 1 of the present embodiment, the control device 30 curves the right side of the lower table 5 upward in a case of an inclination state in which the right side of the upper table 7 is closer to the lower table 5 than the left side thereof.

[0089] According to this configuration, it is possible to pressurize the area on the right side of the workpiece W with the high integrated uniform accuracy.

[0090] In the bending machine 1 of the present embodiment, the control device 30 curves the center of the lower table 5 upward in a case of an inclination state in which the left to right of the upper table 7 is horizontal.

[0091] According to this configuration, it is possible to pressurize the area in the center of the workpiece W with the high integrated uniform accuracy.

[0092] In the present embodiment, the elevating mechanism includes the left and right hydraulic cylinders (an example of elevating units) 9L and 9R provided at left and right ends of the movable table and capable of being controlled independently of each other. The crowning mechanism includes the left and right eccentric shaft units (an example of crowning units) 19L and 19R provided symmetrically with respect to the center position of the lower table 5 in the lateral direction X and capable of being controlled independently of each other.

[0093] According to this configuration, by independently controlling the left and right eccentric shaft units 19L and 19R, it is possible to make the curved shape of the lower table 5 into the symmetrical shape or into the asymmetrical shape. As a result, it is possible to appropriately control the curved state of the lower table 5 so as to conform to the inclination state of the upper table 7.

[0094] Further, in the present embodiment, the control device 30 corrects the outputs of the left and right hydraulic cylinders 9L and 9R and the outputs of the left and right eccentric shaft units 19L and 19R based on the bending angles obtained at the four angle measurement points M1 to M4 positioned at the boundaries of the left, center, and right pressurized ranges La, Lb, and Lc.

[0095] For example, it is considered to carry out the angle measurement at the three points on the left, center, and right of the workpiece W so as to carry out output correction of the hydraulic cylinders 9L and 9R and output correction of the left and right eccentric shaft units 19L and 19R. When the correction is carried out to the left pressurized range La, the outputs of the left and right hydraulic cylinders 9L and 9R are corrected based on two points on the left side and the center, and the outputs of the left and right eccentric shaft units 19L and 19R are corrected based on one point in the center. In this case, the bending angle obtained at the same point (the center point) is used for the output correction of the hydraulic cylinders 9L and 9R and the output correction of the left and right eccentric shaft units 19L and 19R. Therefore, it is difficult to determine how much correction is to be carried out for which output, which may result in a plurality of solutions.

[0096]  In this respect, according to the configuration of the present embodiment, it is possible to use the bending angles obtained at the different angle measurement points M1 to M4 for the output correction of the left and right hydraulic cylinders 9L and 9R and the output correction of the left and right eccentric shaft units 19L and 19R. For example, when the correction is carried out to the left pressurized range La, the outputs of the left and right hydraulic cylinders 9L and 9R are corrected based on the angle measurement points M1 and M3, and the outputs of the left and right eccentric shaft units 19L and 19R are corrected based on the angle measurement point M2 that is different from M1 and M3. In this manner, since it is possible to assign the different angle measurement points to the output correction of the hydraulic cylinders 9L and 9R and to the output correction of the left and right eccentric shaft units 19L and 19R, a correction value for the output is uniquely determined. Therefore, it is possible to carry out appropriate correction.

[0097] It should be noted in the embodiment described above, the bending machine 1 including the upper table 7 corresponding to the movable table and the lower table 5 corresponding to the fixed table is exemplified. However, the bending machine may be configured to include a lower table corresponding to the movable table and an upper table corresponding to the fixed table.

[0098] Further, in the embodiment described above, the bending machine is configured to incline the movable table that moves in the vertical direction Z and curve the fixed table. However, the bending machine may be configured to curve the movable table that moves in the vertical direction Z and to incline the fixed table.

[0099] Further, the bending method according to the present embodiment includes setting the inclination state of the movable table, setting the curved state of the fixed table so as to conform to the inclination state of the movable table, carrying out the partial bending to pressurize the workpiece in the limited pressurized range compared to the pressurized range in which the workpiece W is pressurized by using the entire areas of the first tool and the second tool in the direction X, and carrying out the entire area bending to pressurize the workpiece over the entire area in the lateral direction by changing the combination of the inclination state of the movable table and the curved state of the fixed table and repeating the partial bending while causing a transition of the limited pressurized range.

[0100]  In this manner, in addition to the bending machine 1 shown in the present embodiment, the bending method of carrying out the bending of the workpiece W by using the bending machine 1 also functions as a part of the present invention. Then, this bending method also achieves the same effect as the bending machine 1 described above.

[0101] It should be noted that in the present embodiment, the transition among the pressurized ranges takes place in the order of the left side, the center, and the right side of the workpiece W. However, the transition among the pressurized ranges may take place in any one of (1) the order of the left side, the right side, and the center of the workpiece W, (2) the order of the right side, the center, and the left side of the workpiece W, (3) the order of the right side, the left side, and the center of the workpiece W, (4) the order of the center, the left side, and the center of the workpiece W, and (5) the order of the center, the right side, and the left side of the workpiece W.

[0102] Further, in the present embodiment, the partial bending is carried out to the three pressurized ranges consisting of the left side, the center, and the right side of the workpiece W. However, any partial bending may be used as long as the bending is carried out in the limited pressurized range compared to the pressurized range in which the workpiece W is pressurized by using the entire areas of the upper tool 8 and the lower tool 6 in the lateral direction X. For example, the partial bending may be carried out to two pressurized ranges consisting of a left half and a right half of the workpiece W. Alternatively, the respective areas on the left side, in the center, and on the right side of the workpiece W may be further subdivided, and the partial bending may be carried out in each of the subdivided pressurized ranges.

[0103] Figure 15 is an explanatory diagram showing an example of the workpiece to be processed. In the embodiment described above, the workpiece to be processed is the workpiece W with the one bending line continuous in the lateral direction. However, the workpiece to be processed may be a workpiece W1 to which a cutout C is provided so that bending lines Ba and Bc are unevenly placed to the left and right.

[0104] Figures 16 and 17 are explanatory diagrams showing an operation of pressurizing the workpiece alternately to the left and right. Even to such a workpiece W1, the bending operation is carried out in the same manner as the method described above for each of pressurized ranges La1 and Lc1 corresponding to each of the bending lines Ba and Bc. In other words, the control device 30 not only controls the upper table 7 to be in the inclination state inclined downward to the left but also controls the curved state of the left side of the lower table 5 so as to conform to the inclination state of the upper table 7 inclined downward to the left. In this state, a pressurized range La1 corresponding to the bending line Ba is pressurized. In the same manner, the control device 30 not only controls the upper table 7 to be in the inclination state inclined downward to the right but also controls the curved state of the right side of the lower table 5 so as to conform to the inclination state of the upper table 7 inclined downward to the right. In this state, a pressurized range Lc1 corresponding to the bending line Bc is pressurized.

[0105] In the workpiece W1 with such bending lines Ba and Bc unevenly placed to the left and right, if the upper table 7 is lowered while remaining in the inclination state that is horizontal to the left and right, the pressure reaction force is not applied to the upper table 7 and the lower table 5 at the cutout C. As an uneven pressure reaction force is applied to the upper table 7 and the lower table 5, unnecessary deflection is generated in the upper table 7 and the lower table 5, which makes it impossible to ensure the integrated uniform accuracy at each of the bending lines Ba and Bc. In this regard, according to the present embodiment, in either of the pressurized ranges La1 and Lc1, it is possible to suppress the variation in the bending angle in the pressurized ranges La1 and Lc1. As a result, it is possible to improve the integrated uniform accuracy in the pressurized ranges La1 and Lc1. Thereby, it is possible to obtain the sufficient integrated uniform accuracy in the entire area in the lateral direction X in the workpiece W, that is, in the entire areas of the bending lines unevenly placed to the left and right.

[0106] Further, in the present embodiment, when the pressure is released, the movable table is moved in the vertical direction Z while maintaining the inclination state thereof. However, when the pressurizing operation for a certain pressurized range is ended, the control device 30 may change the movable table, as it is, to the inclination state corresponding to the next pressurized range without elevating the movable table.

[0107] In the present embodiment, the mechanism that curves a part of the table to which the tool is attached is exemplified as the crowning mechanism. However, instead of curving the table itself, the curved shape may be formed in advance by a tool or the like attached to the table. In the present specification, in addition to the method of curving the table itself, a configuration in which the same effect as curving the table is obtained by using equipment attached to the table is also interpreted as the crowning mechanism.

[0108] Although the embodiment of the present invention has been described as above, the statements and drawings forming a part of this disclosure should not be understood to limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques will become apparent to those skilled in the art.

Reference Signs List

[0109] The disclosure of the present application relates to the subject matter described in Japanese Patent Application No. 2021-130572 filed on August 10, 2021, and Japanese Patent Application No. 2022-125542 filed on August 5, 2022, the entire disclosure of which is hereby incorporated by reference.

Claims

1. A bending machine including a movable table to which a first tool is attached along a lateral direction, and a fixed table arranged to be opposed to the movable table in a vertical direction and to which a second tool is attached along the lateral direction, the movable table being moved in the vertical direction to pressurize a workpiece between the first tool and the second tool in order to carry out bending of the workpiece, the bending machine comprising:

an elevating mechanism configured to move the movable table in the vertical direction and capable of adjusting an inclination state showing an inclination to left and right of the movable table;

a crowning mechanism configured to curve a part of the fixed table; and

a control device configured to control the elevating mechanism and the crowning mechanism, wherein

the control device sets the inclination state of the movable table and also sets a curved state of the fixed table to conform to the inclination state of the movable table in order in order to carry out partial bending to pressurize a limited pressurized range compared to a pressurized range in which the workpiece is pressurized by using entire areas of the first tool and the second tool in the lateral direction, and

the control device changes a combination of the inclination state of the movable table and the curved state of the fixed table and repeats the partial bending while causing a transition of the limited pressurized range in order to carry out entire area bending to pressurize the workpiece over an entire area in the lateral direction.

2. The bending machine according to claim 1, wherein the control device repeats the entire area bending a plurality of times to bend the workpiece step by step to a target bending angle.

3. The bending machine according to claim 1 or 2, wherein

the elevating mechanism can move the movable table in a range from a top dead center at which the movable table is separated from the fixed table by a predetermined distance to a bottom dead center at which the movable table comes closest to the fixed table, and

the control device sets the inclination state of the movable table before the movable table reaches the bottom dead center when the partial bending is carried out.

4. The bending machine according to claim 3, wherein, after the partial bending, the control device moves the movable table toward the top dead center within a range in which the first tool and the workpiece are in contact with each other by spring back of the workpiece, and then changes a combination of the inclination state of the movable table and the curved state of the fixed table.

5. The bending machine according to claim 4, wherein the control device moves the movable table toward the top dead center while maintaining the inclination state thereof when the workpiece is pressurized in the limited pressurized range.

6. The bending machine according to claim 1 or 2, wherein the control device curves a left side of the fixed table upward when the movable table is in an inclination state in which a left side of the movable table is closer to the fixed table than a right side of the movable table.

7. The bending machine according to claim 1 or 2, wherein the control device curves a right side of the fixed table upward when the movable table is in an inclination state in which a right side of the movable table is closer to the fixed table than a left side of the movable table.

8. The bending machine according to claim 1 or 2, wherein the control device curves a center of the fixed table upward when the movable table is in an inclination state in which the left and right of the movable table is horizontal.

9. The bending machine according to claim 1 or 2, wherein

the elevating mechanism includes left and right elevating units provided at left and right ends of the movable table and capable of being controlled independently of each other, and

the crowning mechanism includes left and right crowning units provided symmetrically with respect to a center position of the fixed table in the lateral direction and capable of being controlled independently of each other.

10. The bending machine according to claim 9, wherein when the workpiece is pressurized after being divided into three pressurized ranges of a left side, a center, and a right side, the control device corrects outputs of the left and right elevating units and outputs of the left and right crowning units based on bending angles obtained at four angle measurement points positioned at boundaries of the respective pressurized ranges.

11. A bending machine including a movable table to which a first tool is attached along a lateral direction, and a fixed table arranged to be opposed to the movable table in a vertical direction and to which a second tool is attached along the lateral direction, the movable table being moved in the vertical direction to pressurize a workpiece between the first tool and the second tool in order to carry out bending of the workpiece, the bending machine comprising:

an elevating mechanism configured to move the movable table in the vertical direction;

an inclination mechanism capable of adjusting an inclination state showing an inclination to left and right of the fixed table;

a crowning mechanism configured to curve a part of the movable table; and

a control device configured to control the elevating mechanism, the inclination mechanism, and the crowning mechanism, wherein

the control device sets the inclination state of the fixed table and also sets a curved state of the movable table to conform to the inclination state of the fixed table in order to carry out partial bending to pressurize a limited pressurized range compared to a pressurized range when the workpiece is pressurized by using entire areas of the first tool and the second tool in the lateral direction, and

the control device changes a combination of the inclination state of the fixed table and the curved state of the movable table and repeats the partial bending while causing a transition of the limited pressurized range in order to carry out entire area bending to pressurize the workpiece over an entire area in the lateral direction.

12. A bending method of carrying out bending of a workpiece in which a bending machine including a movable table to which a first tool is attached along a lateral direction and a fixed table arranged to be opposed to the movable table in a vertical direction and to which a second tool is attached along the lateral direction, carries out bending of a workpiece by moving the movable table in the vertical direction to pressurize the workpiece between the first tool and the second tool, the bending method comprising:

setting an inclination state of the movable table;

setting a curved state of the fixed table so as to conform to the inclination state of the movable table;

carrying out partial bending to pressurize a limited pressurized range compared to a pressurized range when the workpiece is pressurized by using entire areas of the first tool and the second tool in the lateral direction; and

carrying out entire area bending to pressurize the workpiece over an entire area in the lateral direction by changing a combination of the inclination state of the movable table and the curved state of the fixed table and repeating the partial bending while causing a transition of the limited pressurized range.

Drawing