Bending machine

Abstract

A rotary motive power unit (25) has a high-speed motor unit (26), a pressure-application motor unit (27), a clutch (29), and a motive power transmission mechanism (35) for transmitting torque of the high-speed motor unit (26) and the pressure-application motor unit (27) to a ball screw mechanism (55). The motive power transmission mechanism (35) includes a second driving pulley (37b) and a second driven pulley (38b) having a diameter larger than that of the second driving pulley (37b). The clutch (29) is disposed coaxially with a second rotation axis (A2) of the pressure-application motor unit (27), and selectively blocks transmission of torque from the pressure-application motor unit (27) to the second driving pulley (37b).

Description

Bending machine

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

[0002] A press brake, which is a type of bending machine, performs bending on a workpiece by moving a movable table, on which dies and other dies are mounted, up and down relative to a fixed table, on which dies and other dies are mounted. The table drive device that drives the movable table includes a rotary power unit and a conversion mechanism that converts the rotary motion caused by the torque of the rotary power unit into linear motion along the vertical direction, thereby moving the movable table up and down.

[0003] Patent Document 1 discloses a press brake that moves an upper table up and down using the relative rotational motion of a ball screw shaft and a ball screw nut of a ball screw mechanism. The press brake includes a first power transmission unit and a second power transmission unit. The first power transmission unit transmits the rotation of a first motor to the ball screw nut at high speed and low torque. The second power transmission unit transmits the rotation of a second motor to a drive rotor at low speed and high torque. The drive rotor is configured to be connectable to the ball screw nut via a clutch unit.

[0004] International Publication No. 2018 / 079175

[0005] However, in the technique of Patent Document 1, the torque of the second motor is amplified and transmitted to the ball screw nut in accordance with the ratio of the diameter of the output shaft pulley attached to the output shaft of the second motor to the diameter of the rotary drive body. Because a large torque acts on the drive rotor, it is necessary to increase the transmission capacity of the clutch connecting the ball screw nut and the drive rotor. This results in a problem of an increase in the size of the clutch, and ultimately the size of the bending machine.

[0006] A first aspect of one or more embodiments is a bending machine including a movable table disposed vertically opposite a fixed table, a rotational power unit that generates torque, a conversion mechanism that converts rotational motion generated by the torque of the rotational power unit into linear motion along the vertical direction to move the movable table vertically, and a control device that controls the rotational power unit to bend a workpiece using dies attached to the fixed table and the movable table. The rotational power unit includes a high-speed motor unit, a pressure motor unit that rotates at a slower speed than the high-speed motor unit and outputs high torque, a power transmission mechanism that transmits the torque of the high-speed motor unit to the conversion mechanism and the torque of the pressure motor unit to the conversion mechanism, and a clutch. The power transmission mechanism includes a drive rotor that rotates by the torque transmitted from the pressure motor unit, and a rotatable driven rotor connected to the conversion mechanism, the driven rotor having a diameter larger than that of the drive rotor and transmitting the rotation of the drive rotor at a reduced speed. The clutch is disposed coaxially with the rotation axis of the pressure motor unit and selectively interrupts transmission of torque from the pressure motor unit to the drive rotor. The control device has two switchable operating modes: a high-speed mode in which the movable table is moved by driving the high-speed motor unit with torque disconnected by the clutch, and a high-torque mode in which the movable table is moved by driving the pressure motor unit with torque transmitted by the clutch.

[0007] According to one or more embodiments of the bending machine, it is possible to prevent the clutch and the bending machine from becoming larger.

[0008] FIG. 1 is a front view schematically showing the structure of a press brake according to a first embodiment. FIG. 2 is a side view schematically showing a table drive device of the press brake according to the first embodiment. FIG. 3 is a diagram illustrating a power transmission mechanism. FIG. 4 is a conceptual diagram showing gear elements (mechanical elements) that transmit torque. FIG. 5 is a conceptual diagram showing gear elements (mechanical elements) that transmit torque. FIG. 6 is a side view schematically showing a table drive device of a press brake according to a second embodiment. FIG. 7 is a side view showing a modified example of the table drive device of the press brake according to the first embodiment. FIG. 8 is a side view showing a modified example of the table drive device of the press brake according to the first embodiment.

[0009] Hereinafter, with reference to the drawings, a bending machine according to this embodiment will be described using a press brake as an example.

[0010] First Embodiment FIG. 1 is a front view schematically illustrating the structure of a press brake 1 according to a first embodiment. FIG. 2 is a side view schematically illustrating a table drive device 20 of the press brake 1 according to the first embodiment. In this specification, directions are defined as left-right, front-rear, and up-down. The left-right and front-rear directions correspond to two directions that are orthogonal to the horizontal direction, and the up-down direction corresponds to the vertical direction. In the drawings, the right, left, up, down, front, and rear directions are indicated by RT, LT, UP, DN, FR, and RR, respectively. In FIG. 1, the front-rear direction corresponds to the direction perpendicular to the paper surface, and in FIG. 2, the left-right direction corresponds to the direction perpendicular to the paper surface. These directions are used merely for convenience in describing the press brake 1 according to this embodiment.

[0011] The press brake 1 is a bending machine that performs bending on a plate-shaped workpiece such as sheet metal by cooperation of an upper tool P such as a punch and a lower tool D such as a die. The press brake 1 includes left and right side plates 2, a lower table 5 which is a fixed table, an upper table 7 which is a movable table, left and right table drive devices 20, and a control device 100.

[0012] The left and right side plates 2 are arranged opposite each other and spaced apart in the left-right direction.

[0013] The lower table 5 extends in the left-right direction and is supported by the front lower parts of the left and right side plates 2. A lower die holder 6 that detachably holds a lower die D is provided above the lower table 5 along the left-right direction.

[0014] The upper table 7 extends in the left-right direction and is supported on the front upper parts of the left and right side plates 2 so as to face the lower table 5. The upper table 7 is configured to be movable in the up-down direction relative to the left and right side plates 2. An upper die holder 8 that detachably holds an upper die P is provided below the upper table 7 along the left-right direction.

[0015] The left and right table drive devices 20 are fixed to the upper parts of the left and right side plates 2, respectively. Each table drive device 20 is a drive device that moves the upper table 7 in the up and down direction. As shown in FIG. 2 , the table drive device 20 is mainly composed of a rotation power unit 25 and a ball screw mechanism 55.

[0016] The rotational power unit 25 generates torque for operating the ball screw mechanism 55. The rotational power unit 25 is composed of a high-speed motor unit 26, a pressure motor unit 27, a clutch 29, and a power transmission mechanism 35.

[0017] The high-speed motor unit 26 is composed of a first drive motor 26a. The first drive motor 26a is a device that generates torque using electrical energy, such as a servo motor. The first drive motor 26a is disposed along a first rotation axis A1, and the output shaft of the first drive motor 26a rotates around the first rotation axis A1.

[0018] The pressure motor unit 27 is composed of a second drive motor 27a and a reducer 27b. The second drive motor 27a is a device that generates torque using electrical energy, such as a servo motor. The reducer 27b reduces the rotation (torque) of the second drive motor 27a and outputs it. The pressure motor unit 27 outputs high torque at a slower rotation speed than the high-speed motor unit 26. The second drive motor 27a and the reducer 27b are arranged coaxially with the second rotation axis A2, and the pressure motor unit 27, i.e., the output shafts of the second drive motor 27a and the reducer 27b, rotate about the second rotation axis A2.

[0019] In this embodiment, the high-speed motor unit 26 and the pressure motor unit 27 are arranged on separate rotation axes A1 and A2. The high-speed motor unit 26 is arranged with its output shaft (the output shaft of the first drive motor 26a) facing upward, and the pressure motor unit 27 is also arranged with its output shaft (the output shaft of the second drive motor 27a) facing upward.

[0020] The clutch 29 transmits or blocks torque from the pressure motor unit 27 to the power transmission mechanism 35. The clutch 29 is a meshing clutch that transmits torque by meshing teeth, such as a tooth clutch, but is not limited to this and may be a friction clutch or the like.

[0021] The clutch 29 is disposed coaxially with the rotation axis A2 of the pressure motor unit 27 (second drive motor 27a). The clutch 29 is disposed between the reducer 27b of the pressure motor unit 27 and a second drive pulley 37b of the power transmission mechanism 35 (described later). For example, when the teeth of the clutch 29 are engaged (transmission state), the clutch 29 transmits torque from the output shaft of the reducer 27b to the second drive pulley 37b. On the other hand, when the teeth of the clutch 29 are not engaged (release state), the clutch 29 interrupts the transmission of torque from the output shaft of the reducer 27b to the second drive pulley 37b.

[0022] The power transmission mechanism 35 is made up of a first timing belt 36a, a second timing belt 36b, a first driving pulley 37a, a second driving pulley 37b, a first driven pulley 38a, and a second driven pulley 38b.

[0023] The first timing belt 36a is stretched between the first driving pulley 37a and the first driven pulley 38a. The second timing belt 36b is stretched between the second driving pulley 37b and the second driven pulley 38b. The first and second timing belts 36a, 36b may be chains instead of belts. Power transmission between the first driving pulley 37a and the first driven pulley 38a, and power transmission between the first driving pulley 37a and the first driven pulley 38a may be performed by gears or other cogwheels.

[0024] The first drive pulley 37a is disposed coaxially with the first rotation axis A1 of the high-speed motor unit 26. The first drive pulley 37a is connected to the output shaft of the first drive motor 26a and rotates by torque transmitted from the first drive motor 26a. The second drive pulley 37b is disposed coaxially with the second rotation axis A2 of the pressure motor unit 27. The second drive pulley 37b is connected to the output shaft of the reducer 27b via the clutch 29 and rotates by torque transmitted from the reducer 27b (drive rotor).

[0025] The first and second driven pulleys 38a, 38b are arranged coaxially with the third rotation axis A3 of the ball screw mechanism 55 and are coupled to the ball screw nut 56 of the ball screw mechanism 55. The first and second driven pulleys 38a, 38b may be separate structures or may be integrated into a multi-stage pulley. As shown in FIG. 3 , the diameter Df of the second driven pulley 38b is set larger than the diameter Dd of the second drive pulley 37b. The second driven pulley 38b reduces the rotation of the second drive pulley 37b by a factor of Dd / Df and transmits it to the ball screw nut 56 (driven rotor). The diameter of the first driven pulley 38a is the same as the diameter of the first drive pulley 37a, and the first driven pulley 38a transmits the rotation of the first drive pulley 37a without any change. However, the diameter of the first driven pulley 38a may be different from the diameter of the first driving pulley 37a, and the first driven pulley 38a may transmit the rotation of the first driving pulley 37a by slowing down or accelerating it.

[0026] The ball screw mechanism 55 is a conversion mechanism that converts rotational motion due to the torque of the rotational power unit 25 into linear motion, thereby moving the upper table 7 in the vertical direction. The ball screw mechanism 55 includes a ball screw nut 56 and a ball screw shaft 57. The ball screw nut 56 is supported via a bearing inside the housing of the ball screw mechanism 55. The ball screw nut 56 is connected to the driven pulley 38 of the power transmission mechanism 35, and rotates in accordance with the rotation of the driven pulley 38. The ball screw shaft 57 is threadedly engaged with the ball screw nut 56, and moves in the vertical direction as the ball screw nut 56 rotates forward and backward.

[0027] A connection block 60 is connected to the lower end of the ball screw mechanism 55, specifically the lower end of the ball screw shaft 57. A suspension bolt 61 hanging down in the vertical direction is attached to the lower end of the connection block 60, and the suspension bolt 61 supports a support shaft 62 that passes through the upper table 7 in the front-to-rear direction. The ball screw shaft 57 is connected to the upper table 7 via the connection block 60, which includes the suspension bolt 61 and the support shaft 62.

[0028] A control device 100 such as an NC (Numerical Control) device that controls the operation of the press brake 1 is supported on the side plate 2 via a connecting arm.

[0029] The control device 100 is configured by a computer having a hardware processor such as a CPU (Central Processing Unit), a memory, and various interfaces. The memory and various interfaces are connected to the hardware processor via a bus. The various functions of the control device 100 are realized by having the hardware processor execute programs stored in the memory.

[0030] The control device 100 controls the rotary power unit 25. The control device 100 has two switchable operating modes: a high-speed mode and a high-torque mode. The high-speed mode is an operating mode in which the upper table 7 is moved by driving the high-speed motor unit 26 with torque disconnected by the clutch 29. The high-torque mode is an operating mode in which the upper table 7 is moved by driving the pressure motor unit 27 with torque transmitted by the clutch 29.

[0031] The control of the press brake 1 for bending a workpiece will now be described. When bending a workpiece using the press brake 1, the workpiece is first positioned on the lower die D. At this time, the upper table 7 is held at a predetermined upper end position. The clutch 29 is set to a released state. In other words, the transmission of torque from the pressure motor unit 27 to the power transmission mechanism 35 is interrupted.

[0032] First, the control device 100 drives the high-speed motor unit 26 in the rotation direction for moving the upper table 7 downward. This rotates the output shaft of the high-speed motor unit 26 (the output shaft of the first drive motor 26a), which outputs low torque at high speed, and the upper table 7 descends at high speed (high-speed mode).

[0033] When the upper table 7 moves to a predetermined low-speed switch position (approach position), the control device 100 stops the high-speed motor unit 26. The control device 100 switches the clutch 29 to a transmission state, thereby transmitting torque from the pressure motor unit 27 to the power transmission mechanism 35. The control device 100 drives the pressure motor unit 27 in the rotation direction for moving the upper table 7 downward. This rotates the output shaft of the pressure motor unit 27, which outputs high torque at low rotation speed, and the upper table 7 descends at a low speed (high torque mode).

[0034] As one of the features of this embodiment, when the upper table 7 is moved downward in the high torque mode, the control device 100 performs reversal control to drive the high-speed motor unit in the direction opposite to the rotation direction when moving the upper table 7 downward. Details of the reversal control will be described later.

[0035] The control device 100 controls the pressure motor unit 27 to stop the upper table 7 at a predetermined lower end position (stroke position). As the upper table 7 reaches the lower end position, the workpiece is pressed between the upper die P and the lower die D and bent to the desired angle.

[0036] Next, the control device 100 drives the pressure motor unit 27 in the rotation direction for moving the upper table 7 upward, thereby causing the upper table 7 to rise at a low speed.

[0037] When the upper table 7 rises to a predetermined high-speed switching position, the control device 100 stops the pressure motor unit 27. The control device 100 switches the clutch 29 to a released state, thereby cutting off torque transmission from the pressure motor unit 27 to the power transmission mechanism 35.

[0038] The control device 100 drives the high-speed motor unit 26 in the rotation direction for moving the upper table 7 upward. This rotates the output shaft of the high-speed motor unit 26, and the upper table 7 rises at high speed. When the upper table 7 reaches the upper end position, the control device 100 stops the high-speed motor unit.

[0039] The workpiece is bent through a series of steps in the press brake 1. The operation of the reversal control will now be described.

[0040] As the upper table 7 descends in high torque mode, the upper table 7 decelerates to stop at the lower end position with the workpiece being pressed between the upper die P and the lower die D. When the upper table 7 starts moving from the low-speed switching position and descends at a constant speed, a torque (negative torque) acts on the second drive motor 27a in a direction that pushes the upper table 7 downward. As the upper table 7 approaches the lower end position, the deceleration torque of the second drive motor 27a acts, causing the upper table 7 to decelerate, and finally the upper table 7 is positioned at the lower end position.

[0041] 4 and 5 are conceptual diagrams showing gear elements (mechanical elements) T1 and T2 that transmit torque in the reducer 27b and the clutch 29. The figures depict the main parts of the axially rotating gear elements T1 and T2, with the rotation directions of the gear elements T1 and T2 corresponding to the left-right direction on the page. Of the gear elements T1 and T2, the gear element T1 is the gear element connected to the second drive pulley 37b side, and the gear element T2 is the gear element connected to the second drive motor 27a side.

[0042] A gap is intentionally provided between the gear elements T1 and T2 to allow the machine to operate smoothly. In Figures 4 and 5, the gap is depicted as a space in the left-right direction between the teeth. When the frictional force of the gear elements T1 and T2 alone is no longer sufficient to support the upper table 7, which is a heavy object, the gear element T1 rotates by a small amount ΔG, causing the upper table 7 to move downward. For this reason, even if the control device 100 stops the pressure motor unit 27 in accordance with the lower end position, the upper table 7 may still deviate from the lower end position.

[0043] In high-load bending, such as bending a thick plate, a high bending reaction force acts on the upper table 7 from the workpiece, and the bending reaction force acts in a direction that supports the weight of the upper table 7. Therefore, the phenomenon of unstable positioning of the upper table 7 occurs particularly frequently in low-load bending, such as bending a thin plate. In addition to this, such a phenomenon can also occur in offset bending, in which one of the left and right table drive devices 20 is under a low load.

[0044] In consideration of such phenomena, when the control device 100 moves the upper table 7 downward in high torque mode, it performs reverse control while transmitting torque via the clutch 29. By performing reverse control, the high-speed motor unit 26 is driven in the opposite direction to the pressure motor unit 27, so that rotation R1, which is opposite to rotation R2 of gear element T2, acts on the gear element T1. This maintains a state in which the gear element T2 continues to press the gear element T1 until the upper table 7 reaches the lower end position. Since minute movements of the gear element T1 are suppressed, downward movement of the upper table 7 can be suppressed. Therefore, the upper table 7 is accurately positioned relative to the lower end position. Since the positioning of the upper table 7 is stabilized, machining accuracy can be improved.

[0045] The slight movement of the gear element T1 occurs during the deceleration period in which the upper table 7 is decelerated. Therefore, the period in which the reverse control is performed only needs to include at least the deceleration period. For example, the control device 100 may start the reverse control in synchronization with the timing at which the upper table 7 starts to decelerate, or may start the reverse control a certain time before the timing at which the deceleration starts.

[0046] As described above, the unstable positioning of the upper table 7 occurs particularly frequently in low-load bending processes, such as bending thin plates. Therefore, the control device 100 may perform inversion control in cases such as low-load bending where the load for bending the workpiece is lower than a predetermined threshold. This allows appropriate control to be performed in situations where the positioning of the upper table 7 becomes unstable.

[0047] In the case of high-load bending where the load for bending the workpiece is equal to or greater than a threshold, the above-described reversal control is not necessary. On the other hand, the control device 100 may perform assist control to drive the high-speed motor unit 26 in the rotation direction when moving the upper table 7 downward. This increases the pressure applied by the upper table 7, making it possible to perform bending on workpieces that require a high load.

[0048] As described above, the press brake 1 according to this embodiment includes the upper table 7 arranged vertically opposite the lower table 5, the rotational power unit 25 that generates torque, the ball screw mechanism 55 that converts rotational motion due to the torque of the rotational power unit 25 into linear motion along the vertical direction to move the upper table 7 vertically, and the control device 100 that controls the rotational power unit 25 to bend the workpiece using the dies P and D attached to the lower table 5 and the upper table 7, respectively. The rotational power unit 25 includes a high-speed motor unit 26, a pressure motor unit 27 that outputs high torque at a slower rotation speed than the high-speed motor unit 26, a power transmission mechanism 35 that transmits the torque of the high-speed motor unit 26 to the ball screw mechanism 55 and transmits the torque of the pressure motor unit 27 to the ball screw mechanism 55, and a clutch 29. The power transmission mechanism 35 includes a second drive pulley 37b that rotates by torque transmitted from the pressure motor unit 27, and a rotatable second driven pulley 38b that is connected to the ball screw mechanism 55 and has a diameter larger than that of the second drive pulley 37b, and transmits the rotation of the second drive pulley 37b at a reduced speed. The clutch 29 is disposed coaxially with the rotation axis A2 of the pressure motor unit 27 and selectively interrupts the transmission of torque from the pressure motor unit 27 to the second drive pulley 37b. The control device 100 has switchable operating modes: a high-speed mode in which the upper table 7 is moved by driving the high-speed motor unit 26 with torque interrupted by the clutch 29, and a high-torque mode in which the upper table 7 is moved by driving the pressure motor unit 27 with torque transmitted by the clutch 29.

[0049] The diameter Df of the second driven pulley 38b is set larger than the diameter Dd of the second drive pulley 37b (see FIG. 3). Therefore, the second driven pulley 38b amplifies the torque of the pressure motor unit 27 by a factor of Df / Dd and transmits it to the ball screw nut 56. In the power transmission path, the torque upstream of the second drive pulley 37b is relatively smaller than the torque downstream of the second driven pulley 38b. Because the clutch 29 is located closer to the pressure motor unit 27 than the second drive pulley 37b, the transmission capacity of the clutch 29 can be small. This prevents the clutch 29 from becoming too large, and ultimately prevents the press brake 1 itself from becoming too large.

[0050] Furthermore, with the press brake 1 according to this embodiment, the upper table 7 can be accurately positioned relative to the lower end position by performing inversion control. Since the positioning of the upper table 7 is stable, it is possible to improve processing accuracy.

[0051] When a meshing clutch is used for the clutch 29, the gap between the teeth of the clutch is also transmitted to the ball screw mechanism 55. In this embodiment, the clutch 29 is disposed closer to the pressure motor unit 27 than the second drive pulley 37b, so the gap is reduced by a factor of Dd / Df before being transmitted to the ball screw mechanism 55. Therefore, the positioning accuracy of the upper table 7 can be improved compared to when the clutch 29 is provided downstream of the second driven pulley 38b.

[0052] In this embodiment, the high-speed motor unit 26 includes a first drive motor 26a. The pressure motor unit 27 includes a second drive motor 27a and a reducer 27b that reduces the rotation of the second drive motor 27a and outputs the reduced rotation. With this configuration, in addition to the reduction in speed achieved by the power transmission mechanism 35, the pressure motor unit 27 includes the reducer 27b, so that the pressure motor unit 27 can obtain high torque at low rotation speeds.

[0053] In this embodiment, the high-speed motor unit 26 is composed of only the first drive motor 26 a. However, the high-speed motor unit 26 may include a reducer, similar to the pressure motor unit 27, as long as it rotates at a higher speed and outputs a lower torque than the pressure motor unit 27.

[0054] In this embodiment, the power transmission mechanism 35 includes a first drive pulley 37a to which the high-speed motor unit 26 is connected, a second drive pulley 37b to which the pressure motor unit 27 is connected, first and second driven pulleys 38a, 38b connected to the ball screw mechanism 55, a first timing belt 36a stretched between the first drive pulley 37a and the first driven pulley 38a, and a second timing belt 36b stretched between the second drive pulley 37b and the second driven pulley 38b. This configuration allows the reduction ratio to be set according to the diameter ratio between the second drive pulley 37b and the second driven pulley 38b. This allows for flexible torque and speed settings.

[0055] Furthermore, since the high-speed motor unit 26 and the pressure motor unit 27 are not aligned vertically, the height of the machine can be reduced.

[0056] Second Embodiment A press brake 1 according to a second embodiment will be described below. One of the features of the press brake 1 according to the second embodiment is the configuration of the rotation power unit 25 and the power transmission mechanism 35. Differences from the first embodiment will be mainly described below with reference to Fig. 6. Fig. 6 is a side view schematically showing the table drive device 20 of the press brake 1 according to the second embodiment.

[0057] In this embodiment, the high-speed motor unit 26 and the pressure motor unit 27 are arranged so as to face each other vertically with the power transmission mechanism 35 in between. Specifically, the high-speed motor unit 26 is arranged above the power transmission mechanism 35, and the pressure motor unit 27 is arranged below the power transmission mechanism 35. The high-speed motor unit 26 and the pressure motor unit 27 are arranged coaxially along a common rotation axis A1. In other words, the first drive motor 26a, the second drive motor 27a, and the reducer 27b are arranged coaxially along the common rotation axis A1.

[0058] The power transmission mechanism 35 transmits the torque of the rotational power unit 25 to the ball screw mechanism 55. The power transmission mechanism 35 is made up of a timing belt 36, a drive pulley 37, and a driven pulley 38.

[0059] The timing belt 36 is stretched between a drive pulley 37 and a driven pulley 38. The drive pulley 37 is connected to the output shaft of a first drive motor 26 a. The drive pulley 37 is also connected to the output shaft of a reducer 27 b via a clutch 29. A ball screw nut 56 of a ball screw mechanism 55 is connected to the driven pulley 38.

[0060] As in the first embodiment, the diameter of the driven pulley 38 is set to be larger than the diameter of the drive pulley 37. As a result, the driven pulley 38 reduces the rotation speed of the drive pulley 37 and transmits it to the ball screw nut 56.

[0061] With this configuration, in the power transmission path, the torque acting on the upstream side of the drive pulley 37 is relatively smaller than the torque acting on the downstream side of the driven pulley 38. Because the clutch 29 is disposed closer to the pressure motor unit 27 than the drive pulley 37, it is sufficient if the transmission capacity of the clutch 29 is small. Therefore, it is possible to prevent the clutch 29 from becoming large, and ultimately to prevent the press brake 1 itself from becoming large.

[0062] Furthermore, the high-speed motor unit 26 and the pressure motor unit 27 can share mechanical components such as the timing belt 36 and the drive pulley 37. This reduces the inertia of the mechanical components while suppressing increases in costs. Furthermore, because the high-speed motor unit 26 and the pressure motor unit 27 are arranged side by side in the vertical direction, the expansion of space in the left-right and front-rear directions can be suppressed. This allows for space-saving of the machine.

[0063] The press brake 1 according to the first and second embodiments has been described above. The clutch 29 is not limited to the above-described configuration as long as it is provided in the power transmission path from the second drive motor 27a to the drive pulley. For example, as shown in FIG. 7, the clutch 29 may be interposed between the second drive motor 27a and the reducer 27b. Furthermore, as shown in FIG. 8, the clutch 29 may be provided inside the reducer 27b.

[0064] Note that, depending on the reducer 27b, there may be a mechanism in which the rotational axis A2 of the output shaft of the second drive motor 27a and the rotational axis of the output shaft of the reducer 27b are not coaxial. As long as the clutch 29 is provided in the power transmission path from the second drive motor 27a to the drive pulley, it may be disposed in a non-coaxial relationship with the rotational axis A2 of the output shaft of the second drive motor 27a. For example, the clutch 29 may be provided between the reducer 27b and the drive pulley. Alternatively, the clutch 29 may be provided inside the reducer 27b.

[0065] In the first or second embodiment, rotational motion is input to the ball screw nut 56 of the ball screw mechanism 55, and this rotational motion is converted into linear motion by the ball screw shaft 57. However, rotational motion may be input to the ball screw shaft 57, and this rotational motion may be converted into linear motion by the ball screw nut 56.

[0066] Although the present embodiment has been described, the description and drawings forming a part of this embodiment should not be understood as limiting this embodiment, and various alternative embodiments, implementations and operating techniques will become apparent to those skilled in the art from this embodiment.

[0067] The disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2023-144246 filed with the Japan Patent Office on September 6, 2023, and Japanese Patent Application No. 2024-128788 filed with the Japan Patent Office on August 5, 2024, the entire disclosures of which are incorporated herein by reference.

Claims

1. A device comprising: a movable table disposed vertically opposite a fixed table; a rotational power unit which generates torque; a conversion mechanism which converts rotational motion due to the torque of the rotational power unit into linear motion along the vertical direction, thereby moving the movable table vertically; and a control device which controls the rotational power unit to bend a workpiece using dies attached to the fixed table and the movable table, respectively; wherein the rotational power unit has: a high-speed motor unit; a pressure motor unit which rotates at a slower speed than the high-speed motor unit and outputs high torque; a power transmission mechanism which transmits the torque of the high-speed motor unit to the conversion mechanism and transmits the torque of the pressure motor unit to the conversion mechanism; and a clutch; wherein the power transmission mechanism includes: a drive rotor which rotates by the torque transmitted from the pressure motor unit; and a rotatable driven rotor which is connected to the conversion mechanism, has a diameter larger than a diameter of the drive rotor, and transmits the rotation of the drive rotor at a reduced speed; and wherein the clutch A bending machine arranged coaxially with the rotation axis of the pressure motor unit, selectively cutting off the transmission of torque from the pressure motor unit to the drive rotor, and the control device having switchable operating modes including a high-speed mode in which the movable table is moved by driving the high-speed motor unit with torque cut off by the clutch, and a high-torque mode in which the movable table is moved by driving the pressure motor unit with torque transmitted by the clutch.

2. The bending machine according to claim 1, wherein the high-speed motor unit includes a first drive motor, and the pressure motor unit includes a second drive motor and a reducer that reduces the rotation of the second drive motor and outputs it.

3. The bending machine according to claim 2, wherein the clutch is provided in a power transmission path from the second drive motor to the drive rotor.

4. The bending machine according to claim 2, wherein the clutch is provided inside the reducer.

5. A movable table disposed vertically opposite a fixed table, a rotational power unit which generates torque, a conversion mechanism which converts rotational motion due to the torque of the rotational power unit into linear motion along the vertical direction to move the movable table vertically, and a control device which controls the rotational power unit to bend a workpiece using dies attached to the fixed table and the movable table, respectively, wherein the rotational power unit has: a high-speed motor unit including a first drive motor; a pressure motor unit including a second drive motor and a reducer which decelerates and outputs the rotation of the second drive motor; a power transmission mechanism which transmits the torque of the high-speed motor unit to the conversion mechanism and transmits the torque of the pressure motor unit to the conversion mechanism; and a clutch, wherein the power transmission mechanism includes: a drive rotor which rotates by the torque transmitted from the reducer; and a rotatable driven rotor which is connected to the conversion mechanism, has a diameter larger than the diameter of the drive rotor, and transmits the rotation of the drive rotor at a reduced speed, and wherein the clutch A bending machine provided in a power transmission path from the second drive motor to the drive rotor, selectively cutting off the transmission of torque to the drive rotor, wherein the control device has, as switchable operating modes, a high-speed mode in which the movable table is moved by driving the high-speed motor unit with torque cut off by the clutch, and a high-torque mode in which the movable table is moved by driving the pressure motor unit with torque transmitted by the clutch.

6. The bending machine according to claim 5, wherein the clutch is disposed in the reducer.

7. A bending machine as claimed in any one of claims 1 to 6, wherein the power transmission mechanism includes: a drive pulley as the driving rotor to which the high-speed motor unit and the pressure motor unit are respectively connected; a driven pulley as the driven rotor connected to the conversion mechanism; and a belt stretched between the drive pulley and the driven pulley; and the high-speed motor unit is coaxially arranged on the opposite side of the pressure motor unit with the drive pulley in between.

8. A bending machine as claimed in any one of claims 1 to 6, wherein the power transmission mechanism includes: a first drive pulley to which the high-speed motor unit is connected; a second drive pulley as the drive rotor to which the pressure motor unit is connected; first and second driven pulleys as the driven rotors connected to the conversion mechanism; a first belt stretched between the first drive pulley and the first driven pulley; and a second belt stretched between the second drive pulley and the second driven pulley.

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