PRINTING MECHANISM OF OFFSET PRINTING MACHINE

Abstract

 A printing mechanism of an offset printing machine includes a plating roller (1), a transferring roller (4), and an imprinting roller (2). The plating roller (1) is sleeved on a plate shaft (16). The transferring roller (4) is sleeved on a transfer shaft (21). The imprinting roller (2) is rotatably provided on a machine frame (3). The plating roller (1) is correspondingly matched with the transferring roller (4). The plating roller (1) and the transferring roller (4) maintain to abut and roll against each other. The plate shaft (16) is rotatably provided on the machine frame (3). The transfer shaft (21) is provided to rotate around an axis thereof. The position of the axis of the transfer shaft (21) on a transfer shaft running trajectory (40) is adjustable. When transferring rollers (4) of different outer diameters are selected, the position of the axis of the transfer shaft (21) on the transfer shaft running trajectory (40) is adjusted, so that each of the transferring rollers (4) of the different outer diameters maintains to abut and roll against the imprinting roller (2). The printing mechanism of the offset printing machine may use plating rollers and transferring rollers of different outer diameters, improting printing speed and efficiency, and improving printing accuracy.

Description

Technical Field

[0001] The present invention relates to a printing device, and more specifically to a printing mechanism of an offset printing machine.

Background

[0002] An offset printing machine is a lithographic printing machine in which when printing, a printed graphic is printed onto the rubber blanket of a transferring roller from the printing plate of a plating roller, and then transferred onto the paper from the transferring roller. The printing mechanism of the offset printing machine includes a plating roller, a transferring roller and an imprinting roller, where the three rollers cooperate with each other to complete paper printing.

[0003] A web offset printing machine is an offset printing machine for printing a web material, whose existing printing method is an intermittent offset printing method. That is, regardless of the change in the printed pattern length of a printed matter, the outer diameters of the plating roller and the transferring roller are fixed. When the printed pattern length of the printed matter is changed, the maximum printable circumference of the plating roller is unequal to the printed pattern length of the printed matter. If the printed pattern length is less than the maximum printable length of the plating roller, a relatively large blank (an area without printed pattern) is generated between adjacent two printed patterns on the printed paper, which causes a large waste and thus is disadvantageous for printing. In order to achieve a more ideal printing, a notch is designed on each of the plating roller and the transferring roller, and the two notches are set in synchronization correspondingly. When the notch on the transferring roller faces the imprinting roller, the printed matter (such as paper and film) is retracted under a driving force of a front and rear traction to eliminate the printing blank on the paper, while printing is performed when running in a forward direction, forming an back-and-forth intermittent printing method. This printing method has the following obvious drawbacks in printing: on one hand, the printing speed is hard to go up, affecting printing efficiency; and on the other hand, the tension applied to the printed matter is not stable, which is prone to cause tensile deformation, affecting the printing accuracy and printing effect.

Summary

[0004] In view of the technical problems existing in the art described in the background, the technical problem to be solved in the present invention is to provide a printing mechanism of an offset printing machine capable of replacing plating rollers and transferring rollers of different outer diameters, so that the outer surface circumferences (i.e., the roller surfaces) of the plating rollers and the transferring rollers correspond to a printed pattern length of a printed matter without a retraction during printing, and the material feeding of the printed matter is stable, thereby promoting the printing speed and the printing efficiency, and improving the printing accuracy and printing effect.

[0005] In order to solve the above technical problem, the present invention employs the following technical solution: a printing mechanism of an offset printing machine includes a plating roller, a transferring roller, and an imprinting roller, wherein, the plating roller is sleeved on a plate shaft; the transferring roller is sleeved on a transfer shaft; the imprinting roller is rotatably provided on a machine frame; the plating roller is correspondingly matched with the transferring roller; the plating roller and the transferring roller maintain to abut and roll against each other; the plate shaft is rotatably provided on the machine frame; the transfer shaft is provided to rotate around an axis thereof; a position of the axis of the transfer shaft is adjustable on a transfer shaft running trajectory; and when transferring rollers of different outer diameters are selected, the position of the axis of the transfer shaft on the transfer shaft running trajectory is adjusted, so that each of the transferring rollers of the different outer diameters maintains to abut and roll against the imprinting roller.

[0006] A curved groove is provided on the machine frame; the curved groove forms the transfer shaft running trajectory; the transfer shaft of the transferring roller is provided on the curved groove by a mounting base; the transfer shaft of the transferring roller is rotatably provided on the mounting base; and a position of the mounting base on the curved groove is adjustable.

[0007] The transfer shaft running trajectory is a circular arc trajectory; the transferring rollers of three different outer diameters are optionally selected; three axis positions of the transfer shaft are correspondingly provided on the circular arc trajectory; and each of the transferring rollers at the three axis positions maintains to abut and roll against the imprinting roller.

[0008] The three different outer diameters includes a maximum outer diameter, a minimum outer diameter, and an intermediate outer diameter, respectively.

[0009] A position of the imprinting roller on the machine frame is adjustable in the radial direction.

[0010] The transfer shaft is provided to rotate on a swinging arm; the swinging arm is swingably provided in the machine frame; and the the circular arc trajectory of the transfer shaft running trajectory is formed by swinging the swing arm, and the position of the axis of the transfer shaft is adjustable on the circular arc trajectory.

[0011] The swinging arm is provided on the machine frame to swing by a swinging arm shaft; and a position of the swinging arm shaft on the machine frame is adjustable in the radial direction.

[0012] The swinging arm is driven by a driving device to reciprocate around the swinging arm shaft on the machine frame; the driving device includes a pushing rod, a jacking rod, a cylinder transmission and a screw transmission; the cylinder transmission includes a cylinder; the screw transmission includes a screw, a nut and a slider; the nut is provided on the slider; the screw is driven by a power source for driving the nut to drive the slider to move up and down on the machine frame; the pushing rod is hinged on the swinging arm; the jacking rod is hinged on the slider; the pushing rod and the jacking rod are hinged to each other; and the pushing rod or/and the jacking rod are further drivably connected to the cylinder.

[0013] The cylinder is a double-stroke cylinder or double cylinders; a piston rod of the cylinder is hinged together with the pushing rod and the jacking rod; and the cylinder is swingably provided on a cylinder base.

[0014] A plating roller replacement port is provided on the machine frame; a first end cover is equipped on the plating roller replacement port; a bearing matched with the plate shaft is provided in the first end cover; a transferring roller replacement port is provided on the machine frame; the swinging arm is located at a side of the transferring roller replacement port; a second end cover is provided on the swinging arm; the second end cover is provided on an end cover mounting port of the swinging arm; and a bearing matched with the transfer shaft is provided in the second end cover.

[0015] The present invention has the following advantages: the printing mechanism of the offset printing machine can replace plating rollers and the transferring rollers of different outer diameters; printing of different printing pattern lengths is realized; it is ensured that print patterns on roll paper are continuous between units (there are almost no blanks); the utilization of the roll paper is improved and the retraction of the roll paper is avoided, which effectively improves the printing speed and printing efficiency, and does not affect the paper feeding. The paper tension is stable; which improves the printing accuracy. Thus, the present invention possesses prominent substantive features and remarkable improvements over the prior art.

Brief Description of the Drawings

[0016] The details and working principles of the implementations and embodiments of the present invention is described below with reference to the accompanying drawings.

FIG. 1 is a schematic view of a structure of the present invention.

FIG. 2 is a cross-sectional view on the A-A direction of FIG. 1.

FIG. 3 is a cross-sectional view on the B-B direction of FIG. 1.

Detailed Description of the Embodiments

[0017] Referring to the accompanying drawings, a printing mechanism of an offset printing machine in the present embodiment includes the plating roller 1, the transferring roller 4 and the imprinting roller 2, and paper printing is realized by the cooperation of the three rollers. The plating roller 1 is sleeved on the plate shaft 16, and the transferring roller sleeve 4 is sleeved on a transfer shaft 21. Therefore, plating rollers and transferring rollers of different outer diameters can be replaced on the shafts. A positioning pin and a notch are provided between the shaft and the roller to position and match with each other, thereby ensuring that there is no relative sliding between the shaft and the roller. Alternatively, an elastic layer is provided in an inner hole of the roller and a gas hole is provided on the shaft. The gas hole is controlled to blow gas by a gas source and a gas valve. When the roller is sleeved on the shaft, the gas is blown by the gas hole to open up the elastic layer in the inner hole of the roller. After the roller is sleeved in place, the gas hole is stopped to blow the gas, and the elastic layer in the inner hole of the roller shrinks and clasps on the shaft.

[0018] The imprinting roller 2 is rotatably provided on a machine frame, and the imprinting roller is configured to be driven by the motor 19 (e.g., a servo motor) to rotate. The plating roller 1 is correspondingly matched with the transferring roller 4. That is, the roller surface of the transferring roller 4 is correspondingly matched with a pattern unit on the plating roller 1 in N times, where N is a positive integer, preferably 1 or 2 for a convenience of the transferring of the printing pattern. For example, when the plating roller 1 has a same or slightly different size (generally referring to the outer diameter) with the transferring roller 4, the roller surface of the transferring roller 4 can be just correspondingly matched with one pattern unit on the plating roller 1 (the relationship of 1 time); or, the roller surface (i.e., the outer surface circumference) of the roller 4 corresponds to two pattern units on the plating roller (the relationship of 2 times). Referring to the accompanying drawings, in the present embodiment, the relationship of 1 time is used, and the plating roller has the same size with the transferring roller.

[0019] The plating roller 1 and the transferring roller 4 maintain to abut and roll against each other. The pattern on the plating roller is transferred onto the transferring roller. The plate shaft 16 is rotatably provided on the machine frame 3. The plate shaft 16 is configured to be driven by the motor 13 (e.g., a servo motor) to rotate, and drives the plating roller on the plate shaft to rotate. The transfer shaft 21 is provided to rotate around its axis. The transfer shaft 21 is configured to be driven by the motor 20 (e.g., a servo motor) to rotate, and drives the transferring roller 4 on the transfer shaft 21 to rotate. A position of the axis of the transfer shaft 21 is adjustable on the transfer shaft running trajectory 40. When transferring rollers of different outer diameters are selected and used, the position of the axis of the transfer shaft 21 on the transfer shaft running trajectory 40 is adjusted, so that each of the transferring rollers 4 of different outer diameters can maintain to abut and roll against the imprinting roller 2. The transferring roller is correspondingly matched with the plating roller in outer diameter, and they maintain to abut and roll against each other while the transferring roller and the imprinting roller maintain to abut and roll against each other. Therefore, when printing patterns of different lengths, the corresponding plating roller and transferring roller can be replaced. Then, the position of the axis of the transfer shaft is adjusted, so that the transferring roller and the plating roller maintain to abut and roll against each other, the transferring roller and the imprinting roller maintain to abut and roll against each other, and the printing patterns on the roll paper are continuous between the units. The utilization of the roll paper is improved and the roll paper does not need to be retracted, which effectively improves the printing speed and efficiency. Moreover, the paper tension and the material feeding are stable.

[0020] A curved groove is provided on the machine frame 3. For example, the curved groove is provided on a wall plate of the machine frame 3. The curved groove forms the transfer shaft running trajectory. The transfer shaft 21 of the transferring roller is provided on the curved groove by a mounting base. The transfer shaft of the transferring roller is rotatably provided on the mounting base. The position of the mounting base on the curved groove is adjustable. The position of the axis of the transfer shaft on the transfer shaft running trajectory is adjusted by adjusting the position of the mounting base on the curved groove.

[0021] The transfer shaft running trajectory 40 is configured to be a circular arc trajectory. Transferring rollers of three different outer diameters are optionally taken. There are correspondingly three axis positions of the transfer shafts on the circular arc trajectory. That is, the three axis positions correspond to the mounting positions of the transferring rollers of the three different outer diameters. The transferring rollers each maintain to abut and roll against (ideally, maintain to be externally tangent against) the imprinting roller at the three axis positions. The three axis positions can be just enough to determine the circular arc trajectory, thereby ensuring that the transferring rollers of three sizes can maintain to abut and roll against the plating roller and the imprinting roller on the circular arc trajectory. At other positions near each of the three axis positions on the circular arc trajectory, transferring rollers of other outer diameters (other than the three optional outer diameters) can also maintain to abut and roll against the imprinting roller and the plating roller by applying different pressures. The three different outer diameters may be a maximum outer diameter, a minimum outer diameter, and an intermediate outer diameter, respectively, such as 245 mm, 145 mm, and 200 mm.

[0022] A position of the imprinting roller 2 on the machine frame 3 is adjustable in the radial direction. That is, the position of the imprinting roller 2 on the machine frame can be changed and adjusted in the radial direction. At an initial position of the imprinting roller, each of the transferring rollers at the three axis positions maintains to abut and roll against the imprinting roller at the initial position, where the initial position refers to a position before the imprinting roller is adjusted. Adjustment may be performed so that a central rotating shaft of the imprinting roller 2 is provided on the eccentric shaft sleeve 23. The position of the imprinting roller in the radial direction is adjusted by adjusting the position of the eccentric shaft sleeve on the machine frame. When the transfer shaft running trajectory 40 is configured to be a circular arc trajectory, it is difficult to ensure that the transferring rollers on the transfer shafts at positions other than the three axis positions of the circular arc trajectory simultaneously maintain to abut and roll against the plating roller and the imprinting roller. By adjusting the position of the imprinting roller in the radial direction, it can be ensured that the respective rollers abut and roll against each other.

[0023] The circular arc trajectory may be in the form of a circular arc groove provided on the machine frame. In the present embodiment, the form of the swinging arms 5, 24 is used, specifically as follows: the transfer shaft 21 of the transferring roller is rotatably provided on the swinging arms 5, 24 (left and right swinging arms, respectively); the transfer shaft 21 is rotated around its axis; the swinging arms 5, 24 are swingably provided on the machine frame 3; the swing of the swinging arms 5, 24 forms a circular arc trajectory, namely, the transfer shaft running trajectory 40; and the position of the axis of the transfer shaft 21 on the circular arc trajectory is adjusted by swinging.

[0024] The circular arc trajectory formed by using the form of the swinging arms also has three axis positions which can be just enough to determine a circular arc trajectory. On the circular arc trajectory, it is ensured that the transferring rollers of at least three sizes can maintain to abut and roll against (ideally, maintain to be externally tangent against) the plating roller and the imprinting roller, achieving adjustment of the at least three sizes. The transferring rollers at the vicinity of the three sizes can also maintain to abut and roll against each other by pressure adjustment. However, the transferring rollers on the transfer shaft at other positions on the circular arc trajectory are difficult to simultaneously maintain to abut and roll against the plating roller and the imprinting roller. In order to ensure that the respective rollers abut and roll against each other, in addition to adjusting the position of the imprinting roller on the machine frame in the radial direction, the circular arc trajectory may also be adjusted. The adjustment may further change the size of the printing pressure between the rollers. For example, the swinging arms 5, 24 are provided to swing on the machine frame 3 by the swinging arm shaft 22. The position of the swinging arm shaft 22 on the machine frame 3 is adjustable in the radial direction, that is, the position of the swinging arm shaft 22 on the machine frame can be changed in the radial direction. At an initial position of the swinging arm shaft 22, swinging arm each of the transferring rollers located at the three axis positions maintains to abut and roll against the imprinting roller, where the initial position refers to a position before the swinging arm shaft is adjusted. By adjusting the positions of the swinging arms in the radial direction, the position of the circular arc trajectory can be adjusted accordingly. The swinging arm shaft can be adjusted to be on the eccentric shaft sleeve, and the position of the swinging arm shaft in the radial direction is adjusted by adjusting the position of the eccentric shaft sleeve on the machine frame.

[0025] The swinging arms 5, 24 are driven by a driving device to reciprocate around the swinging arm shaft on the machine frame 3. The driving device may directly drive the swinging arms to swing by using a cylinder to top push the swinging arms or using a lead screw-equipped motor. In the present embodiment, preferably, the following structure is used: the driving device includes the pushing rod 6, the jacking rod 8, a cylinder transmission and a screw transmission. The cylinder transmission includes a cylinder. The screw transmission device includes the screw 11, a nut and the slider 9. The nut is provided on the slider 9. The screw 11 is driven by the power source 12 (such as a servo motor and a torque motor) for driving the nut to drive the slider 9 to move up and down on the machine frame. The guiding rail 7 is provided on the machine frame for the slider to move up and down. The pushing rod 6 is hinged on the swinging arm 5. The jacking rod 8 is hinged on the slider 9. The pushing rod and the jacking rod are hinged to each other. The pushing rod is drivably connected to the cylinder, or the jacking rod is drivably connected to the cylinder, or a hinge point between the pushing rod and the jacking rod is drivably connected to the cylinder. The pushing rod and the jacking rod are driven to move by cooperating with the cylinder. In the present embodiment, when the driving device is in operation, the power source 12 drives the screw, and the screw 11 drives the nut to drive the slider 9 to move up and down on the machine frame. The slider drives the swinging arm to swing back and forth by cooperation with the jacking rod, the pushing rod and the cylinder. After initially arriving in place, the power source stops driving the screw, and the cylinder communicates with an air source to pressurize against the swinging arm. By adjusting the pressure change of the cylinder, the pressure of maintaining the transferring roller on the swinging arm to abut and roll against the imprinting roller and the plating roller can be adjusted. When the slider of the screw transmission is locked on the machine frame by lifting the screw and the nut, the transferring roller can be prevented from jumping and shaking during printing, thereby avoiding the occurrence of the phenomenon of ink stick. The cylinder employs a double-stroke cylinder or double cylinders. The piston rod of the cylinder is hinged together with the pushing rod and the jacking rod. The cylinder is swingably provided on a cylinder base. The cylinder employing the double-stroke cylinder or double cylinders can perform a double-stroke operation. One small stroke may be set in the double stroke. When the swinging arm is swung in the small stroke, the transferring roller can be separated from the other two rollers for inspection, debugging or the like. The double cylinders 25, 26 are used in the figure.

[0026] The machine frame 3 is provided with a plating roller replacement port. The first end cover 17 is provided on the plating roller replacement port. The bearing 18 matched with the plate shaft 16 is provided in the first end cover 17. The transferring roller replacement port 15 is provided on the machine frame 3. The swinging arm 5 is located on a side of the transferring roller replacement port 15, which is an outer side in the present embodiment, and obviously, may be provided on an inner side. The second end cover 27 is provided on the swinging arm 5, and the second end cover is provided on an end cover mounting port of the swinging arm. The bearing 10 matched with the transfer shaft 21 is provided in the second end cover 27. A groove may further be provided on a wall plate for the movement of the transfer shaft on the swinging arm. In the present embodiment, the swinging arms 5 and 24 are provided on left and right sides of the wall plate of the machine frame, respectively. The plating roller replacement port and the transferring roller replacement port are both located on the right wall plate of the machine frame. An end cover mounting port for mounting the second end cover 27 is provided on the right side of the swinging arm 5. The operation of replacing the roller is described by taking the swinging arm as an example. When replacing the roller, the swinging arm swings to the position of the transferring roller replacement port, and the second end cover on the right swinging arm is removed from the transfer shaft. After the removal and separation, as long as the swinging arm swings to the position of the transferring roller replacement port again, the transferring roller on the transfer shaft can be replaced. After the replacement, the swinging arm swings to the transfer shaft so that the second end cover is reinstalled to match with the transfer shaft. In addition, the first end cover of the wall plate is opened, the plating roller is removed from the plate shaft for replacement at the plating roller replacement port, and the first end cover is reinstalled after the replacement.

Claims

1. A printing mechanism of an offset printing machine, comprising a plating roller (1), a transferring roller (4), and an imprinting roller (2), wherein, the plating roller (1) is sleeved on a plate shaft (16); the transferring roller (4) is sleeved on a transfer shaft (21); the imprinting roller (2) is rotatably provided on a machine frame (3); the plating roller (1) is correspondingly matched with the transferring roller (4); the plating roller (1) and the transferring roller (4) maintain to abut and roll against each other; the plate shaft (16) is rotatably provided on the machine frame (3); the transfer shaft (21) is provided to rotate around an axis thereof; a position of the axis of the transfer shaft (21) is adjustable on a transfer shaft running trajectory (40); and when transferring rollers (4) of different outer diameters are selected and used, the position of the axis of the transfer shaft (21) on the transfer shaft running trajectory (40) is adjusted, so that each of the transferring rollers (4) of the different outer diameters each maintain to abut and roll against the imprinting roller (2).

2. The printing mechanism of the offset printing machine of claim 1, wherein, a curved groove is provided on the machine frame (3) ; the curved groove forms the transfer shaft running trajectory (40); the transfer shaft (21) of the transferring roller (4) is provided on the curved groove by a mounting base; the transfer shaft (21) of the transferring roller (4) is rotatably provided on the mounting base; and a position of the mounting base on the curved groove is adjustable.

3. The printing mechanism of the offset printing machine of claim 1, wherein, the transfer shaft running trajectory (40) is a circular arc trajectory; transferring rollers (4) of three different outer diameters (a, b, c) are optionally selected; three axis positions of the transfer shaft (21) are correspondingly provided on the circular arc trajectory; and each of the transferring rollers (4) at the three axis positions maintains to abut and roll against the imprinting roller (2).

4. The printing mechanism of the offset printing machine of claim 1, wherein, when the plating roller (1) is correspondingly matched with the transferring roller (4), a roller surface of the transferring roller (4) is correspondingly matched with a pattern unit on the plating roller in N times(1), wherein N is a positive integer.

5. The printing mechanism of the offset printing machine of claim 3, wherein, a position of the imprinting roller (2) on the machine frame (3) is adjustable in radial direction.

6. The printing mechanism of the offset printing machine of claim 3, wherein, the transfer shaft (21) is provided to rotate on swinging arms (5, 24); each of the swinging arms (5, 24) is swingably provided in the machine frame (3); and the circular arc trajectory of the transfer shaft running trajectory (40) is formed by swinging the swinging arm (5, 24), and the position of the axis of the transfer shaft (21) is adjustable on the circular arc trajectory.

7. The printing mechanism of the offset printing machine of claim 6, wherein, each of the swinging arms (5, 24) is provided on the machine frame (3) to swing by a swinging arm shaft (22); and a position of the swinging arm shaft (22) on the machine frame (3) is adjustable in radial direction.

8. The printing mechanism of the offset printing machine of claim 6, wherein, each of the swinging arms (5, 24) is driven by a driving device to reciprocate around the swinging arm shaft (22) on the machine frame (3); the driving device comprises a pushing rod (6), a jacking rod (8), a cylinder transmission and a screw transmission; the cylinder transmission comprises a cylinder; the screw transmission comprises a screw (11), a nut and a slider (9); the nut is provided on the slider (9); the screw is driven by a power source for driving the nut to drive the slider (9) to move up and down on the machine frame (3); the pushing rod (6) is hinged on the swinging arm (5); the jacking rod (8) is hinged on the slider (9); the pushing rod and the jacking rod are hinged to each other; and the pushing rod or/and the jacking rod are further drivably connected to the cylinder.

9. The printing mechanism of the offset printing machine of claim 8, wherein, the cylinder is a double-stroke cylinder or double cylinders; a piston rod of the cylinder is hinged together with the pushing rod and the jacking rod; and the cylinder is swingably provided on a cylinder base.

10. The printing mechanism of the offset printing machine of claim 6, wherein, a plating roller replacement port is provided on the machine frame (3) is provided with; a first end cover (17) is equipped on the plating roller replacement port; a bearing (18) matched with the plate shaft (16) is provided on the first end cover (17); a transferring roller replacement port is provided on the machine frame (3); the swinging arm (5) is located at a side of the transferring roller replacement port (15); a second end cover (27) is provided on the swinging arm (5) ; the second end cover (27) is provided on an end cover mounting port of the swinging arm (5); and a bearing matched with the transfer shaft (21) is provided in the second end cover (27) .

Drawing