Warp-beaming machine

Abstract

 A warp-beaming machine includes one or more sectional beams, each sectional beam having a yarn sheet wound around the sectional beam, one or more feeding-tension-applying units for applying forces to their respective sectional beams, a take-up roller which comes into contact with a warp sheet obtained by combining the yarn sheets unwound from the respective sectional beams, a setting unit for outputting a bias value, and a torque-applying unit for applying a rotational torque corresponding to the bias value to the take-up roller. The feeding-tension-applying units and the torque-applying unit are all activated while a beaming operation for winding the warp sheet around a take-up beam is being performed, and the force applied to the take-up roller, which corresponds to the bias value, is set quickly and accurately.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates to a warp-beaming machine which winds a warp sheet around a take-up beam at a desired take-up tension by applying a force of a take-up roller to the warp sheet, the warp sheet being obtained by combining one or more yarn sheets unwound from respective sectional beams, and more specifically relates to a technique for setting a force applied to the take-up roller to an optimum value on the basis of the relationship between feeding tensions applied to the sectional beams and the desired take-up tension.

2. Description of the Related Art

[0002] In a typical warp-beaming machine, yarn sheets are unwound from several to more than ten sectional beams and are combined into a single warp sheet, and the warp sheet is wound around a single take-up beam to obtain a warp beam. In such a warp-beaming machine, it is important to manage a tension applied to the warp sheet which is wound around the take-up beam, that is, a take-up tension, and various tension control devices have been proposed. For example, a tension control device is known in which each of the sectional beams is provided with a feeding-tension-applying unit including an actuator, such as a powder brake, for applying a feeding tension to the corresponding yarn sheet and the rotational speed of the take-up beam is controlled such that the warp sheet moves at a predetermined moving speed. All of the actuators generate the same feeding tension and the warp sheet receives a correcting tension corresponding to the sum of the feeding tensions of the sectional beams from a torque-applying unit connected to a take-up roller, so that a predetermined take-up tension is applied to the warp sheet. In this tension control device, each of the feeding tensions applied to the sectional beams is controlled by an open-loop control system and the take-up tension is controlled by a closed-loop control system. Accordingly, the overall control device has high accuracy and is easily obtained.

[0003] When T1 is the sum of the feeding tensions of the sectional beams, T3 is the predetermined take-up tension, and T2 is the correcting tension applied to the take-up roller, T2 is calculated as T2 = T3 - T1 from the force balance. Accordingly, the correcting tension T2 must be set as accurate a bias value as possible for the take-up roller in the closed-loop system. However, when powder brakes are used as actuators, generated braking forces greatly vary with time. Therefore, in order to set an accurate bias value before starting the operation of the warp-beaming machine, an operator must start a preliminary steady-state operation, put the control system into an open-loop state to stop the tension correction, and manually set the bias value for the take-up roller while monitoring the take-up tension so that the detected take-up tension becomes the same as the predetermined take-up tension (refer to, for example, Japanese Unexamined Patent Application Publication No. 64-69468, pages 1 to 7).

[0004] As described above, the preliminary steady-state operation must be performed for setting an accurate bias value. When the preliminary steady-state operation for setting the bias value is being performed, the warp sheet is wound at a tension largely different from the desired take-up tension since the bias value is adjusted manually. The difference from the desired take-up tension leads to breakage of warp yarns and failure in shedding motion in a weaving process performed afterwards, and thus the operation of a loom is adversely affected. In addition, the warp sheet wound while the bias value is being set is relatively long, such as several tens to several hundreds of meters, and is discarded since it would adversely affect the operation of the loom, and thus the warp sheet is wasted. In addition, a so-called beam fracture or the like easily occurs in the surface of the take-up beam when the bias value is being set, and this adversely affects the warp yarns wound around the take-up beam afterwards. In such a case, the quality of the warp beam is further degraded. These problems also occur in warp-beaming machines which do not have the above-described closed-loop system (that is, the tension control device) for controlling the take-up tension.

SUMMARY OF THE INVENTION

[0005] Accordingly, an object of the present invention is to provide a warp-beaming machine which winds a warp sheet around a take-up beam at a desired take-up tension by applying a force of a take-up roller to the warp sheet, the warp sheet being obtained by combining one or more yarn sheets unwound from respective sectional beams, wherein the force of the take-up roller, that is, a bias value, is quickly and accurately set without performing the preliminary steady-state operation for manual setting.

[0006] According to a first aspect of the present invention, a warp-beaming machine includes one or more rotatably supported sectional beams, each sectional beam having a yarn sheet wound around the sectional beam; one or more feeding-tension-applying units provided for the respective sectional beams, each feeding-tension-applying unit applying a force to the corresponding sectional beam on the basis of a feeding tension set for the sectional beam and thereby applying the feeding tension to the corresponding yarn sheet; a take-up roller which comes into contact with a warp sheet obtained by combining the yarn sheets unwound from the respective sectional beams; a setting unit for outputting a bias value; and a torque-applying unit for applying a rotational torque corresponding to the bias value to the take-up roller. The feeding-tension-applying units and the torque-applying unit are all activated while a beaming operation for winding the warp sheet around a take-up beam is being performed, and the setting unit receives a desired take-up tension which is to be applied to the warp sheet when the warp sheet is wound around the take-up beam and the feeding tensions for the respective sectional beams in advance and outputs the result of subtraction of the sum of the feeding tensions from the desired take-up tension to the torque-applying unit as the bias value.

[0007] According to the first aspect of the present invention, the setting unit receives the desired take-up tension and the feeding tensions for the respective sectional beams and outputs the difference T2 obtained by subtracting the sum T1 of the feeding tensions for the respective sectional beams from the desired take-up tension T3 as the bias value. Therefore, the optimum bias value is quickly set without performing the preliminary steady-state operation, which is required in the known warp-beaming machine. Since the bias value is set before starting the operation of the warp-beaming machine, the warp sheet is wound at a desired take-up tension from the start. Therefore, the quality of the warp beam is increased compared to the known warp-beaming machine, and the quality degradation of the warp beam and the waste of the warp yarns are prevented.

[0008] Preferably, the desired take-up tension is maintained while the steady-state operation is being performed. More specifically, according to a second aspect of the present invention, a warp-beaming machine includes one or more rotatably supported sectional beams, each sectional beam having a yarn sheet wound around the sectional beam; one or more feeding-tension-applying units provided for the respective sectional beams, each feeding-tension-applying unit applying a force to the corresponding sectional beam on the basis of a feeding tension set for the sectional beam and thereby applying the feeding tension to the corresponding yarn sheet; a take-up roller which comes into contact with a warp sheet obtained by combining the yarn sheets unwound from the respective sectional beams; a tension sensor for detecting a warp tension at a position downstream of the take-up roller; a setting unit for outputting a bias value; and a torque-applying unit for applying a rotational torque corresponding to the bias value to the take-up roller. The feeding-tension-applying units and the torque-applying unit are all activated while a beaming operation for winding the warp sheet around a take-up beam is being performed. In addition, the setting unit receives a desired take-up tension which is to be applied to the warp sheet when the warp sheet is wound around the take-up beam and the feeding tensions for the respective sectional beams in advance and outputs the result of subtraction of the sum of the feeding tensions from the desired take-up tension to the torque-applying unit as the bias value, and the torque-applying unit receives the desired take-up tension and the warp tension from the tension sensor and corrects the bias value by adding an amount of correction corresponding to the difference between the warp tension and the desired take-up tension.

[0009] According to the second aspect of the present invention, the setting unit outputs the difference T2 obtained by subtracting the sum T1 of the feeding tensions for the respective sectional beams from the desired take-up tension T3 as the bias value. Therefore, similar to the first aspect, the optimum bias value is quickly set without performing the preliminary steady-state operation, which is required in the known warp-beaming machine. In addition, the torque-applying unit outputs the sum of the bias value and the amount of correction corresponding to the difference between the detected warp tension and the desired take-up tension as the corrected bias value and applies a torque corresponding to the corrected bias value to the take-up roller. Accordingly, the warp tension in a region between the take-up roller and the take-up beam, that is, the take-up tension, is continuously maintained at the desired take-up tension T3.

[0010] In the above-described first and second aspects of the present invention, each of the feeding-tension-applying units provided for the respective sectional beams may include an actuator for applying a braking torque to the corresponding sectional beam, a force detector for detecting the force applied to the sectional beam, and a torque control unit for controlling the braking torque generated by the actuator on the basis of the feeding tension and the force detected by the force detector. The actuator is not limited as long as it generates a force in accordance with an electrical signal. For example, a powder brake is preferably used as the actuator. However, the present invention is not limited to this, and a rotational actuator, such as a torque motor, may also be used. In the case in which the powder brake is used, even if the braking force is reduced with time due to wear of magnetic powder, such as iron powder, contained in the powder brake, the reduction in the braking force is detected and the torque control unit controls the braking torque so as to maintain the feeding tension. Accordingly, the feeding tension is continuously maintained at the set value. Therefore, the actual force applied to each of the sectional beams is prevented from being reduced to below the set value due to, for example, wear of the powder, and therefore the warp sheet is prevented from being wound around the take-up beam at a take-up tension lower than the desired take-up tension.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 

Fig. 1 is a diagram showing the overall structure of a warp-beaming machine according to the present invention;

Fig. 2 is a diagram showing a peripheral region of a sectional beam shown in Fig. 1;

Fig. 3 is a block diagram of the main part of a control device for controlling the warp-beaming machine; and

Fig. 4 is a block diagram of a correcting-torque command unit shown in Fig. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0012] An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows an example of a warp-beaming machine 10. A base plate 13 is placed in front of a take-up device 11, and n sectional beams 19_a1 to 19_an, where n is an integer of one or more, are rotatably supported by beam stands 15_a1 to 15_an, respectively, which are arranged on the base plate 13 along a moving direction of warp yarns 31.

[0013] The beam stands 15_a1 to 15_an are arranged on a single horizontal line such that the height of the axes of the sectional beams 19_a1 to 19_an gradually increases as the distance from the take-up device 11 increases. In addition, guide rollers 17_a1 to 17_an extending parallel to the axes of the sectional beams 19_a1 to 19_an are disposed near the sectional beams 19_a1 to 19_an, respectively. Similar to the beam stands 15_a1 to 15_an, the guide rollers 17_a1 to 17_an are supported by supporting members (not shown) which are arranged such that the height of the axes of the guide rollers 17_a1 to 17_an gradually increases as the distance from the take-up device 11 increases. The sectional beams 19_a1 to 19_an are connected to powder brakes 33_a1 to 33_an, respectively, which apply braking torques to the rotations of the sectional beams 19_a1 to 19_an. This will be described in more detail below. Sheets of warp yarns 31, that is, yarn sheets, are unwound from the sectional beams 19_a1 to 19_an, are guided upward to the respective guide rollers 17_a1 to 17_an, and are then guided into the take-up device 11. When the axes of the beam stands 15_a1 to 15_an are suitably positioned, the yarn sheets unwound from their respective sectional beams 19_a1 to 19_an can be directly guided to the take-up device 11 such that they do not come into contact with each other. In such a case, the guide rollers 17_a1 to 17_an may be omitted.

[0014] Fig. 2 shows the structure of each of the powder brakes and a peripheral region thereof, the powder brakes applying braking forces to the rotations of the respective sectional beams 19_a1 to 19_an. More specifically, in each sectional beam 19, a flange 35 is provided on each end of a beam shaft 36, and a sheet of multiple warp yarns 31, that is, a yarn sheet, is wound between the flanges 35 and is guided toward the take-up device 11. Each sectional beam 19 (19_a1 to 19_an) is provided with a roll diameter sensor 39 (39_a1 to 39_an) for detecting the diameter of the roll of the yarn sheet. The beam shaft 36 is rotatably supported by a pair of beam stands 15 at both ends thereof with metal parts (not shown) interposed therebetween. In addition, a beam gear 37 is formed integrally with the beam shaft 36 such that they have a common rotational axis.

[0015] A powder brake 40 basically includes a shaft 42, a first driving member 44a, a second driving member 44b, an excitation coil 45a, a stator 45b, and a driven member 46, all of which are contained in a case 41.

[0016] The case 41 has a cylindrical shape with end faces, and a shaft 42, which functions as an output shaft, extends out from the case 41 through one of the end faces. A driven gear 38 is formed integrally with the shaft 42 at the outer end of the shaft 42 such that they have a common axis, and the shaft 42 is rotatably supported by a bearing 43 in the case 41. In addition, the first driving member 44a is fixed to the shaft 42 at the inner end of the shaft 42 such that they have a common rotational axis. The first driving member 44a and the second driving member 44b are composed of a magnetic material, such as iron, and have a plate-like shape (a disc-like shape). In addition, the first driving member 44a and the second driving member 44b are combined together such that they have a common axis and that the peripheral portions thereof face each other with an annular non-magnetic member (not shown) interposed therebetween. Accordingly, a driving member unit 44 obtained by combining the driving members 44a and 44b has a bracket shape in cross section with a magnetic gap provided therein, and a space is provided between surfaces of the driving members 44a and 44b which face each other. The driven member 46 is positioned such that a projection 46a provided thereon extends radially along the surfaces of the driving members 44a and 44b in the space between the driving members 44a and 44b. The projection 46a of the driven member 46 is positioned such that a gap 47b is provided between the end of the projection 46a and an inner surface of the driving member unit 44 at a position corresponding to the magnetic gap between the driving members 44a and 44b, and a base plate of the driven member 46 is fixed to the case 41 such that it cannot rotate. In addition, a space 47a is provided between the projection 46a and the driving member unit 44, and iron powder or the like is enclosed in the space 47a. The stator 45b has a ring-like shape and is disposed outside the driving member unit 44 such that it embraces the excitation coil 45a with a magnetic gap provided at a position corresponding to the magnetic gap provided in the driving member unit 44.

[0017] In the above-described powder brake 40, which is well known in the art, when a direct current is applied to the excitation coil 45a, a magnetic flux φ which passes through the stator 45b, the driving member unit 44, and the projection 46a is generated and the powder collects in the gap 47b. Accordingly, the driving member unit 44 and the driven member 46 are connected with each other by the powder collecting therebetween, and a braking torque corresponding to the supplied current is generated in the driving member 44, that is, in the shaft 42.

[0018] The case 41 of the powder brake 40 is attached to the corresponding beam stand 15 with a stay 48 and a load cell 49 provided therebetween, and the load cell 49 outputs an electrical signal representing a force applied. In addition, the driven gear 38, which is formed integrally with the shaft 42, meshes with the beam gear 37. The load cell 49 detects a reaction force applied to the case 41 in the rotating direction, in other words, the braking torque applied to the corresponding sectional beam by the powder brake 40. The powder brake 40 shown in Fig. 2 is provided for each of the sectional beams 19_a1 to 19_an shown in Fig. 1.

[0019] As shown in Fig. 1, the take-up device 11 includes a plurality of rollers, each of which is rotatably supported by a pair of frames (not shown) at both ends thereof. More specifically, the take-up device 11 includes a first pushing roller 21, a take-up roller 23, a second pushing roller 25, a tension roller 27, and a detachably attached take-up beam 29. An auxiliary motor 24 which generates a predetermined rotational torque is connected to the take-up roller 23, and the first pushing roller 21 and the second pushing roller 25 are arranged such that the sheet of warp yarns 31 obtained by combining the yarn sheets, that is, a warp sheet, is pressed between the take-up roller 23 and the first pushing roller 21 and between the take-up roller 23 and the second pushing roller 25. The tension roller 27 is provided with a tension sensor 28 which detects the tension of the warp yarns 31 on the tension roller 27 and generates an electrical tension signal T. The take-up beam 29 is connected to a take-up motor 30 by a connecting mechanism (not shown) and is provided with a roll diameter sensor 34 which detects the roll diameter of the take-up beam 29. The warp yarns 31 guided toward the take-up device 11 successively pass through a zigzag reed 32 and the above-described rollers and are wound around the take-up beam 29.

[0020] The take-up device 11 is provided with a control device 50 for controlling the auxiliary motor 24, the take-up motor 30, etc. The control device 50 receives the tension signal T from the tension sensor 28 and a roll-diameter signal d₀ from the roll diameter sensor 34, and transmits outputs to the powder brakes 33_a1 to 33_an, the auxiliary motor 24, and the take-up motor 30.

[0021] Fig. 3 is a block diagram showing the inner structure of the control device 50. The control device 50 basically includes a take-up control unit 51 for driving the take-up motor 30, a feeding-torque command unit 55 for supplying an excitation current to each of the powder brakes 33_a1 to 33_an, a correcting-torque command unit 60 for supplying a current for driving the auxiliary motor 24, and a setting unit 80 for outputting yarn-speed command signals and torque command signals to the above-described units.

[0022] The setting unit 80 includes a plurality of setters 80_a, 80_b, 80_c1 to 80_cn, and 80_d, each setter being composed of a variable resistor or the like and setting a value, roll-diameter correctors 81_a1 to 81_an, and a calculator 82. The setters 80_a and 80_b set a low speed S_L1 and a high speed S_H1, respectively, as moving speeds of the warp sheet during the operation. The low speed S_L1 is used when the operation starts, and the high speed S_H1 is used in the steady-state operation. Speed signals S_L1 and S_H1 representing the low and high speeds, respectively, are supplied to the take-up control unit 51.

[0023] The setter 80d sets a desired take-up tension T_S1 for when the warp sheet is wound around the take-up beam 29, and a take-up tension signal T_S1 representing the desired take-up tension is supplied to the calculator 82 and the correcting-torque command unit 60.

[0024] The setters 80_c1 to 80_cn set feeding tensions 80_c1 to 80_cn for the sectional beams 19_a1 to 19_an, respectively, and feeding-tension signals 80_c1 to 80_cn representing the feeding tensions are respectively input to the roll-diameter correctors 81_a1 to 81_an, which are provided for the respective sectional beams, at one of two input terminals. In addition, roll-diameter signals d₁ to d_n from the respective sectional beams are input to the roll-diameter correctors 81_a1 to 81_an at the other one of the two input terminals. The roll-diameter correctors 81_a1 to 81_an correct the received feeding tensions 80_c1 to 80_cn on the basis of the roll diameters d₁ to d_n input thereto, and output feeding-tension signals T_SO1 to T_SOn representing the corrected feeding tensions 81_c1 to 81_cn to the calculator 82 and the feeding-torque command unit 55.

[0025] The calculator 82 calculates a correcting torque to be applied to the sheet of warp yarns 31 by the take-up roller 23, that is, a bias value T_S2, on the basis of the values input thereto, and outputs a bias value signal T_S2 representing the bias value to the correcting-torque command unit 60. The bias value T_S2 is obtained by subtracting the sum of the feeding tensions 81_c1 to 81_cn of the respective sectional beams from the desired take-up tension T_S1 as follows:

[0026] Before starting the operation of the warp-beaming machine, an operator sets the above-described values into the setting unit 80 in accordance with a setting data sheet or the like provided for each production lot. Since the values are set before the operation of the warp-beaming machine starts, the calculator 82 can immediately calculate an optimum bias value T_S2 from Equation (1) and output the result to the correcting-torque command unit 60. In place of the above-described setters, the setting unit 80 may also include a setter having a touch panel or the like with which the values can be individually input and displayed. The calculator 82 may be a hardware circuit (a combination of an adder circuit and a subtractor circuit) or a computer. Alternatively, when a setting device having a touch panel is used as described above, a calculating function of a microcomputer or a soft-ware installed in the setting device may be used for obtaining the output.

[0027] The take-up control unit 51 includes a speed signal generator 52 and a drive circuit 53. The speed signal generator 52 receives the low-speed signal S_L1 and the highspeed signal S_H1 from the setting unit 80, the roll-diameter signal d₀ from the roll diameter sensor 34, and a drive signal S₂ from a sequence control device 84. When the speed signal generator 52 receives the drive signal S₂, it refers to the roll-diameter signal d₀ and outputs a speed command signal S_P1 representing a yarn speed determined on the basis of the low and high speeds S_L1 and S_H1 to the drive circuit 53. More specifically, when the drive signal S₂ is input, the speed signal generator 52 sets a speed command to the low speed S_L1, increases the speed command until it reaches the high speed S_H1, and then maintains the speed command at the high speed S_H1. The drive circuit 53 receives a rotational speed signal S_P0 from a speed detector 54 connected to the take-up motor 30. In addition, the drive circuit 53 includes a known speed control circuit for driving the take-up motor 30 at a speed corresponding to the speed command signal input thereto, and supplies electric power required for driving the take-up motor 30.

[0028] The feeding-torque command unit 55 includes control circuits 56_a1 to 56_an provided for the respective powder brakes 33_a1 to 33_an, each control unit serving as a torque control unit. The control circuits 56_a1 to 56_an include torque signal generators 57_a1 to 57_an and drive circuits 58_a1 to 58_an, respectively. The torque signal generators 57_a1 to 57_an respectively receive the feeding-tension signals T_SO1 to Tson from the setting unit 80 and force signals q_s1 to q_sn from load cells 49_a1 to 49_an. In addition, the torque signal generators 57_a1 to 57_an also receive an operation preparation signal S₁ from the sequence control device 84. When the torque signal generators 57_a1 to 57_an receive the operation preparation signal S₁, they refer to the force signals q_s1 to qsn input as feedback signals and output torque command signals i₁ to i_n for generating torques corresponding to the feeding tension signals T_SO1 to T_SOn (feeding tensions 81_c1 to 81_cn) to the drive circuits 58_a1 to 58_an, respectively. The drive circuits 58_a1 to 58_an supply direct currents (DC currents) corresponding to the torque commands i₁ to i_n to the excitation coils of the powder brakes 33_a1 to 33_an, respectively. Accordingly, the powder brakes 33_a1 to 33_an apply braking torques corresponding to the feeding tension signals T_SO1 to T_SOn (feeding tensions 81_c1 to 81_cn) to the sectional beams 19_a1 to 19_an, respectively, via the shafts 42. Thus, the feeding-torque command unit 55 controls the currents applied to the excitation coils on the basis of forces (braking torques) detected by the load cells 49_a1 to 49_an, so that the torques corresponding to the feeding tension signals T_SO1 to T_SOn (feeding tensions 81_c1 to 81_cn) are generated by the powder brakes. As a result, even if the powder is worn as the operation proceeds, the braking torques corresponding to the feeding tensions can be generated. Although the powder brakes are used as actuators for generating the braking torques in the present embodiment, rotational actuators which generate rotational torques, such as torque motors, may also be used in place of the powder brakes. Alternatively, band brakes and linear actuators for applying forces to the band brakes may be used in combination for applying the braking torques to the shafts. Thus, a detailed mechanism for generating the braking torques is not particularly limited.

[0029] The correcting-torque command unit 60 includes a torque command generator 61 and a drive circuit 72. The torque command generator 61 receives the bias value T_S2 and the desired take-up tension T_S1 from the setting unit 80, the tension signal T from the tension sensor 28, and the operation preparation signal S₁ from the sequence control device 84. When the torque command generator 61 receives the operation preparation signal S₁, it calculates a correction value for maintaining the warp tension T, that is, the detected take-up tension, at the desired take-up tension T_S1, and outputs a torque command signal T_q representing a torque command value T_q to the drive circuit 72, the torque command value T_q being obtained by adding the correction value to the bias value T_S2.

[0030] A feeding-tension-applying unit referred to herein corresponds to the feeding-torque command unit 55, the powder brake 40, the load cell 49, and the gear transmission mechanism for transmitting the braking force to the corresponding sectional beam. In addition, a torque-applying unit for applying a rotational torque to the take-up roller corresponds to the correcting-torque command unit 60 and the auxiliary motor 24.

[0031] Fig. 4 is a block diagram showing the inner structure of the torque command generator 61. The torque command generator 61 mainly includes a corrector unit 62 and an adder 68, and the corrector unit 62 includes a comparator 64, a correction signal generator 65, a determiner 70, and an integrator 66. In addition, a clock-signal generator 67 is connected to the corrector unit 62. The clock-signal generator 67 switches a clock signal C_K output therefrom between on and off at a predetermined control frequency while the drive signal S₂, which will be described below, is being input, and supplies the clock signal C_K to the correction signal generator 65 and the integrator 66.

[0032] The comparator 64 receives the desired take-up tension signal T_S1 and the warp tension signal T, and is connected to a setter 69a which sets thresholds of an allowable range for the desired take-up tension T_S1. The comparator 64 compares the warp tension T with the allowable range for the desired take-up tension T_S1 and outputs a determination signal S₃ representing the result of comparison to the correction signal generator 65. The correction signal generator 65 is connected to a setter 69b which sets an amount of correction output when the determination signal S₃ is input, and receives a determination signal S₄, which will be described below, from the determiner 70. When the clock signal C_K is switched on, the correction signal generator 65 generates an electrical signal corresponding to the amount of correction set in the setter 69b in the direction to eliminate the tension difference by referring to the determination signals S₃ and S₄, and supplies the electrical signal to the integrator 66.

[0033] When a production lot is completed or when the take-up beam is replaced, a clear signal CLR is input to the integrator 66 and the integrator 66 clears (initializes) an integrated value. Otherwise, the integrator 66 maintains the current integrated value. In addition, when the clock signal C_K is switched on, the integrator 66 integrates the correction signal S_C1 input thereto and outputs a signal S_C3 representing the result of integration to one of two input terminals of the adder 68. In addition, the bias value T_S2 is input to the other one of the input terminals of the adder 68 from the setting unit 80. When the drive signal S₂ is not input, the adder 68 outputs the bias value T_S2 as the torque command signal T_q. When the drive signal S₂ is input, the adder 68 outputs the sum of two inputs, that is, the bias value T_S2 and the signal S_C3, to the drive circuit 72 as the torque command signal T_q. The bias value T_S2 is also input to the determiner 70, and the determiner 70 determines whether the bias value T_S2 is positive or negative and outputs the signal S₄ representing the result of the determination to the correction signal generator 65.

[0034] As shown in Fig. 3, the control device 50 is connected to the sequence control device 84 which controls the overall operation of the warp-beaming machine 10. The sequence control device 84 is connected to various operating buttons, such as a start button 85a, a stop button 85b, an inching button, and a low-speed button, sensors for detecting abnormal yarn states, such as a yarn breakage sensor and a fluff detection sensor, sensors for detecting abnormal operation of the take-up device, etc. When a command signal is input from the operating buttons, the sequence control device 84 outputs a command signal (not shown) to perform a required operation of the take-up device 11, such as inching and reverse rotation. In addition, when an abnormal-state signal is input from the above-mentioned sensors, the sequence control device 84 turns off the operation preparation signal S₁ and the drive signal S₂ to stop the take-up device 11.

[0035] When the operator operates the start button 85a, the sequence control device 84 turns on the operation preparation signal S₁ so that the feeding-torque command unit 55 and the correcting-torque command unit 60 are activated. Accordingly, the sectional beams 19_a1 to 19_an receive the braking torques corresponding to the feeding tensions 80_c1 to 80_cn, respectively, and the take-up roller 23 receives the force corresponding to the bias value T_S2. Then, the sequence control device 84 turns on the drive signal S₂ so that the take-up control unit 51 starts rotating the take-up beam 29. Accordingly, the sheet of warp yarns 31 is wound around the take-up beam 29 while moving at a speed which is set to the low speed S_L1 at first, increased until it reaches the high speed S_H1, and then maintained at the high speed S_H1. When the warp yarns 31 start moving, they are unwound from the respective sectional beams 19_a1 to 19_an and the sectional beams 19_a1 to 19_an start rotating. Since the braking torques applied by the powder brakes 33_a1 to 33_an impede the rotations of the sectional beams 19_a1 to 19_an, respectively, the warp yarns 31 receive the feeding tension signals T_SO1 to T_SOn (feeding tensions 81_c1 to 81_cn) while they move.

[0036] In addition, the take-up roller 23 receives the rotating torque corresponding to the bias value T_S2 from the auxiliary motor 24, and is driven and rotated along with the warp yarns 31 while applying the torque to the warp yarns 31. Therefore, the warp yarns 31 which are in contact with the take-up roller 23 receive the force, that is, the tension, corresponding to the bias value T_S2 via the take-up roller 23.

[0037] The warp tension in a region downstream of the take-up roller is balanced with that in a region upstream of the take-up roller, and is therefore determined as the tension applied in the region upstream of the take-up roller, that is, the sum of the tension generated by the take-up roller and the total feeding tension applied by the sectional beams. In addition, it is clear from Equation (1), which determines the above-described bias value T_S2, that the warp tension in the region downstream of the take-up roller is equal to the desired take-up tension T_S1. Thus, the warp sheet is wound around the take-up beam at the warp tension corresponding to the desired take-up tension T_S1 immediately after the start of the beaming operation.

[0038] After the start of the beaming operation, if the warp tension (take-up tension) deviates from the desired take-up tension T_S1 for some reason while the warp yarns 31 are moving, the corrector unit 62 outputs the correction value S_C3 for the initial bias value T_S2. Accordingly, a tension control operation is performed in which the torque command value T_q input to the auxiliary motor 24 is changed such that the warp tension approaches the desired take-up tension with time.

[0039] More specifically, with reference to Fig. 4, when the drive signal S2 is input, the clock-signal generator 67 outputs the clock signal C_K to the correction signal generator 65 and the integrator 66 in the form of pulses with a predetermined control frequency. The comparator 64 continuously compares the warp tension with the allowable range determined by the desired take-up tension T_S1 and the thresholds set by the setter 69a. When the warp tension T deviates out of the threshold range (limit threshold range), the comparator 64 outputs the determination signal S₃ corresponding to the direction of deviation. Accordingly, each time the correction signal generator 65 receives the clock signal C_K, it outputs the correction signal S_C1 corresponding to the amount of correction, which is set in the setter 69b, in accordance with the determination signal S₄.

[0040] The bias value T_S2 may be set not only to a positive value but also to a negative value depending on the relationship between the desired take-up tension T_S1 and the sum of the feeding tensions 80_c1 to 80_cn (or the sum of the corrected feeding tensions 81_c1 to 81_cn obtained using the roll diameters di to dn). In other words, a force may be applied to the take-up roller 23 not only in the direction opposite to the moving direction of the warp yarns 31 but also in the moving direction of the warp yarns 31. Therefore, the amount of correction used in the tension control operation must be changed depending on whether the bias value T_S2 is positive or negative. Accordingly, the determiner 70 determines whether the bias value T_S2 is positive or negative and outputs the determination signal S₄. The correction signal generator 65 converts the amount of correction in accordance with the determination signals S₃ and S₄ so that the tension difference can be eliminated, and outputs the converted amount of correction to the integrator 66 as the correction signal S_C1. The integrator 66 integrates the amount of correction input thereto each time the clock signal C_K is input. The result of integration is input to the adder 68, and thus the torque command value T_q is corrected.

[0041] As an example, a case is considered in which the desired take-up tension T_S1 is larger than the sum of the feeding tensions applied by the sectional beams, that is, a case in which the bias value T_S2 is positive. When the warp tension T is reduced below the lower limit of the threshold range for the take-up tension, the correction signal generator 65 outputs a correction signal S_C1 representing a positive value. Accordingly, the integrated value set in the integrator 66 increases and the torque command value T_q increases from the initial bias value T_S2 with time. In contrast, when the warp tension T is increased above the upper limit of the threshold range of the take-up tension, the correction signal generator 65 outputs a correction signal S_C1 representing a negative value. Accordingly, the integrated value set in the integrator 66 decreases and the torque command value T_q decreases from the initial bias value T_S2 with time. Thus, the warp-tension control operation is performed in which the amount of correction S_C3 for the bias value T_S2 is changed such that the actual total warp tension T, that is, the take-up tension approaches the desired take-up tension T_S1. Due to this tension control operation, even when the take-up tension suddenly changes, it returns to the desired take-up tension in order to maintain the desired take-up tension.

[0042] In the above-described warp-beaming machine 10, when a new lot production is started, the feeding tensions of the sectional beams are set in accordance with the kinds of yarns and the desired take-up tension T_S1 is determined. The desired take-up tension T_S1 may either be higher or lower than the sum of the feeding tensions of the sectional beams since the bias value T_S2 may either be positive or negative as a result of subtraction of the sum of the feeding tensions from the desired take-up tension T_S1. When the bias value T_S2 is positive, the auxiliary motor 24 generates a torque in the direction opposite to the moving direction of the warp sheet (in the clockwise direction in Fig. 1) so as to increase the take-up tension. When the bias value T_S2 is negative, the auxiliary motor 24 generates a torque in the moving direction of the warp sheet (in the counterclockwise direction in Fig. 1).

[0043] In the above-described warp-beaming machine 10, the roll diameters of the sectional beams 19_a1 to 19_an gradually decrease as the beaming operation proceeds, and therefore the actual feeding tensions may become greater or smaller than the predetermined feeding tensions. However, the roll-diameter correctors 81_a1 to 81_an output the corrected feeding tensions 81_c1 to 81_cn which are determined in accordance with the reductions in the roll-diameters d₁ to d_n such that the initial feeding tensions are maintained. The calculator 82 repeats the subtraction of the sum of the feeding tensions 81_c1 to 81_cn from the desire take-up tension T_S1 and continuously outputs the bias value T_S2 which corresponds to the corrected feeding tensions 81_c1 to 81_cn reflecting the reductions in the roll-diameters. Thus, in addition to the above-described tension control operation, the feeding tensions 81_c1 to 81_cn and the bias value T_S2 are also corrected to compensate for the reductions in the roll diameters d₁ to d_n of the sectional beams. Instead of installing the circuits for compensating for the reductions in the roll diameters of the sectional beams in the setting unit 80, the circuits may also be provided downstream of the setting unit 80.

[0044] The above-described embodiment may also be modified as described below. According to the embodiment illustrated in the figures, the determiner 70 is provided so that the amount of correction S_C3 for the bias value T_S2 is added to cause the take-up tension to approach the desired take-up tension T_S1 irrespective of whether the bias value T_S2 is positive or negative. However, the determiner 70 may also be omitted if the bias value T_S2 is determined to be either positive or negative. In such a case, the correction signal generator 65 outputs the correction signal S_C3 based on only the determination signal S₃.

[0045] In the above-described warp-beaming machine 10, the correcting-torque command unit 60 included in the tension control device determines the bias value T_S2 before the operation starts, and then corrects the bias value T_S2 on the basis of the detected total warp tension T (that is, the detected take-up tension), thereby correcting the force applied by the auxiliary motor 24. However, the detailed inner structure of the corrector unit 62 is not limited to that illustrated in Fig. 4. For example, in the structure shown in the figure, the correction signal generator 65 outputs the predetermined amount of correction when the detected take-up tension is outside the range defined by the thresholds. However, the correction signal S_C1 may also be output in accordance with the difference between the detected take-up tension and the desired take-up tension T_S1. In addition, with reference to Fig. 4, the integrator 66 (that is, an integral element) is used for temporally varying the correction value in response to the variation in the tension applied to the warp sheet. However, a proportional element or a differential element may also be added to increase the response speed. In addition, a PID control device including all of them may also be used.

[0046] In the above-described embodiment, a closed-loop tension control system is constructed such that the force (torque) applied to the take-up roller is corrected on the basis of the take-up tension detected by the tension sensor 28 so that the desired take-up tension T_S1 is maintained after the operation starts. However, the structure may also be simplified by omitting the tension control system and applying a force corresponding to the bias value T_S2, which is determined by subtracting the sum of the feeding tensions 81_c1 to 81_cn of the sectional beams from the desired take-up tension T_S1, to the take-up roller 23.

[0047] While the warp-beaming machine 10 is being operated, some of the torque generated by the auxiliary motor 24 in accordance with the bias value T_S2 for the take-up operation is used for driving the take-up roller and the like. Accordingly, the actual force applied to the warp sheet by the take-up roller is probably smaller than the bias value T_S2. Therefore, the bias value T_S2 is preferably corrected to compensate for a mechanical torque loss (mechanical loss) caused by driving the take-up roller or the like. The mechanical loss is considered to increase as the rotational speed increases, and the bias value T_S2 is more preferably corrected to compensate for the mechanical loss in accordance with the moving speed of the warp sheet. More specifically, the adder 68 may be connected to a mechanical-loss compensator (not shown) which outputs a mechanical-loss-compensating value corresponding to the rotational speed of the take-up roller, that is, the moving speed of the warp sheet. In such a case, the adder 68 adds the mechanical-loss-compensating value to the above-described calculation result and outputs the result as the torque command value Tq. However, the mechanical loss compensator may also be omitted.

[0048] In the above-described embodiment, the auxiliary motor 24 is not particularly limited as long as it is an actuator which generates a torque in accordance with a supplied current. For example, the auxiliary motor 24 may be a direct current motor or a torque motor. In addition, the torque of the motor may also be controlled using a current generator in combination, and the method for generating the torque is not limited. In addition, the roll diameters of the sectional beams and the take-up beam may also be estimated on the basis of the relationship between the amount of rotation of each beam and the amount of movement of the warp yarns instead of using the roll diameter sensors 34 and 39 (39a1 to 19an).

[0049] In addition, although the speed signal generator 52, the torque signal generators 57_a1 to 57_an, and the torque command generator 61 included in the control device 50 are composed of independent circuits, they may also be constructed as a single circuit. For example, the sequential processes and control operations, the calculation of the bias value, etc., may of course be performed using a microcomputer and a software program.

Claims

1. A warp-beaming machine (10) comprising:

one or more rotatably supported sectional beams (19_a1 to 19_an), each sectional beam having a yarn sheet wound around the sectional beam;

one or more feeding-tension-applying units provided for the respective sectional beams (19_a1 to 19_an), each feeding-tension-applying unit applying a force to the corresponding sectional beam on the basis of a feeding tension set for the sectional beam and thereby applying the feeding tension to the corresponding yarn sheet;

a take-up roller (23) which comes into contact with a warp sheet obtained by combining the yarn sheets unwound from the respective sectional beams (19_a1 to 19_an);

a setting unit (80) for outputting a bias value; and

a torque-applying unit for applying a rotational torque corresponding to the bias value to the take-up roller (23),

   wherein the feeding-tension-applying units and the torque-applying unit are all activated while a beaming operation for winding the warp sheet around a take-up beam (29) is being performed, and
   wherein the setting unit (80) receives a desired take-up tension which is to be applied to the warp sheet when the warp sheet is wound around the take-up beam (29) and the feeding tensions for the respective sectional beams (19a1 to 19an) in advance and outputs the result of subtraction of the sum of the feeding tensions from the desired take-up tension to the torque-applying unit as the bias value.

2. A warp-beaming machine (10) comprising:

one or more rotatably supported sectional beams (19_a1 to 19_an), each sectional beam having a yarn sheet wound around the sectional beam;

one or more feeding-tension-applying units provided for the respective sectional beams (19a1 to 19an), each feeding-tension-applying unit applying a force to the corresponding sectional beam on the basis of a feeding tension set for the sectional beam and thereby applying the feeding tension to the corresponding yarn sheet;

a take-up roller (23) which comes into contact with a warp sheet obtained by combining the yarn sheets unwound from the respective sectional beams (19a1 to 19an);

a tension sensor for detecting a warp tension at a position downstream of the take-up roller (23);

a setting unit (80) for outputting a bias value; and

a torque-applying unit for applying a rotational torque corresponding to the bias value to the take-up roller (23),

   wherein the feeding-tension-applying units and the torque-applying unit are all activated while a beaming operation for winding the warp sheet around a take-up beam (29) is being performed,
   wherein the setting unit (80) receives a desired take-up tension which is to be applied to the warp sheet when the warp sheet is wound around the take-up beam (29) and the feeding tensions for the respective sectional beams (19a1 to 19an) in advance and outputs the result of subtraction of the sum of the feeding tensions from the desired take-up tension to the torque-applying unit as the bias value, and
   wherein the torque-applying unit receives the desired take-up tension and the warp tension from the tension sensor and corrects the bias value by adding an amount of correction corresponding to the difference between the warp tension and the desired take-up tension.

3. A warp-beaming machine (10) according to one of Claims 1 and 2, wherein each of the feeding-tension-applying units includes an actuator for applying a braking torque to the corresponding sectional beam, a force detector for detecting the force applied to the sectional beam, and a torque control unit for controlling the braking torque generated by the actuator on the basis of the feeding tension and the force detected by the force detector.

Drawing