Bending machine

Abstract

Suppress the increase in size of the clutch and the bending machine. 【Solution means】The rotational power unit 25 includes a high-speed motor unit 26, a pressure motor unit 27, a clutch 29, and a power transmission mechanism 35 that transmits the torques of the high-speed motor unit 26 and the pressure motor unit 27 to a ball mechanism. The power transmission mechanism 35 includes a second drive pulley 37b and a second driven pulley 38b having a diameter larger than the diameter of the drive pulley 37b. The clutch 29 is arranged coaxially with the second rotation axis A2 of the pressure motor unit 27 and selectively blocks the transmission of torque from the pressure motor unit 27 to the second drive pulley 37b.

Description

Technical Field

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

Background Art

[0002] A press brake, which is one type of bending machine, performs bending on a workpiece by moving a movable table on which a mold such as a punch is mounted in the vertical direction with respect to a fixed table on which a mold such as a die is mounted. A table drive device for driving the movable table includes a rotational power unit and a conversion mechanism that converts the rotational motion by the torque of the rotational power unit into a linear motion along the vertical direction to move the movable table in the vertical direction.

[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 rotating body at low speed and high torque. The drive rotating body is configured to be connectable to the ball screw nut by a clutch unit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the method of Patent Document 1, according to the ratio between the diameter of the output shaft pulley attached to the output shaft of the second motor and the diameter of the rotary drive body, the torque of the second motor is amplified and transmitted to the ball screw nut. Since a large torque acts on the drive rotary body, it is necessary to increase the transmission capacity of the clutch that connects the ball screw nut and the drive rotary body. For this reason, there is a problem that the clutch becomes larger, and as a result, the bending machine becomes larger.

Means for Solving the Problems

[0006] The first aspect of one or more embodiments is a bending machine including a movable table disposed to face the fixed table in the vertical direction, a rotary power unit that generates torque, a conversion mechanism that converts the rotary motion due to the torque of the rotary power unit into a linear motion along the vertical direction to move the movable table in the vertical direction, and a control device that bends a workpiece with dies respectively mounted on the fixed table and the movable table by controlling the rotary power unit. The rotary power unit includes a high-speed motor unit, a pressurizing motor unit that outputs high torque at a lower rotational speed than the high-speed motor unit, a power transmission mechanism that transmits the torque of the high-speed motor unit to the conversion mechanism and transmits the torque of the pressurizing motor unit to the conversion mechanism, and a clutch. The power transmission mechanism includes a drive rotary body that rotates by the torque transmitted from the pressurizing motor unit, and a rotatable driven rotary body connected to the conversion mechanism, the driven rotary body having a diameter larger than the diameter of the drive rotary body and reducing and transmitting the rotation of the drive rotary body. The clutch is disposed coaxially with the rotation axis of the pressurizing motor unit and selectively blocks the transmission of torque from the pressurizing motor unit to the drive rotary body. The control device has, as a switchable operation mode, a high-speed mode in which the movable table is moved by driving the high-speed motor unit with the torque blocked by the clutch, and a high-torque mode in which the movable table is moved by driving the pressurizing motor unit with the torque transmitted by the clutch.

Advantages of the Invention

[0007] According to the bending machine according to one or more embodiments, it is possible to suppress the clutch and the increase in size of the bending machine.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0009] Hereinafter, with reference to the drawings, the bending machine according to the present embodiment will be described by exemplifying a press brake.

[0010] (First Embodiment) FIG. 1 is a front view schematically showing the structure of the press brake 1 according to the first embodiment. FIG. 2 is a side view schematically showing the table drive device 20 of the press brake 1 according to the first embodiment. In this specification, as the definition of directions, the left-right direction, the front-back direction, and the up-down direction are used. The left-right direction and the front-back direction correspond to two directions orthogonal to each other in the horizontal direction, and the up-down direction corresponds to the vertical direction. In FIG. 1, the front-back direction corresponds to the direction perpendicular to the paper surface, and in FIG. 2, the left-right direction corresponds to the vertical direction of the paper surface. These directions are only used for convenience in explaining the press brake 1 according to the present embodiment.

[0011] The press brake 1 is a bending machine that performs bending on a plate-shaped workpiece such as sheet metal by the cooperation of an upper die P such as a punch and a lower die D such as a die. The press brake 1 includes left and right side plates 2, a lower table 5 that is a fixed table, an upper table 7 that 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 at intervals in the left-right direction so as to face each other.

[0013] The lower table 5 extends in the left-right direction and is supported at the front lower portions of the left and right side plates 2. A lower die holder 6 for detachably holding the lower die D is provided along the left-right direction on the upper side of the lower table 5.

[0014] The upper table 7 extends in the left-right direction and is supported at the front upper portions 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 with respect to the left and right side plates 2. An upper die holder 8 for detachably holding the upper die P is provided along the left-right direction on the lower side of the upper table 7.

[0015] The left and right table driving devices 20 are respectively fixed to the upper parts of the left and right side plates 2. Each table driving device 20 is a driving device for moving the upper table 7 in the vertical direction. As shown in FIG. 2, the table driving device 20 mainly includes a rotational 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 by electrical energy, for example, a servo motor. The first drive motor 26a is arranged along the 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 speed reducer 27b. The first drive motor 26a is a device that generates torque by electrical energy, for example, a servo motor. The speed 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 lower rotational speed than the high-speed motor unit 26. The second drive motor 27a and the speed reducer 27b are arranged coaxially with the second rotation axis A2, and the output shafts of the pressure motor unit 27, that is, the second drive motor 27a and the speed reducer 27b, rotate around the second rotation axis A2.

[0019] In this embodiment, the high-speed motor unit 26 and the pressure motor unit 27 are respectively arranged on different 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] Clutch 29 transmits torque from the pressurizing motor unit 27 to the power transmission mechanism 35 or cuts off the transmission of this torque. Clutch 29 is an engagement type clutch that performs torque transmission by tooth engagement, for example, a two-tooth clutch, but is not limited to this, and may be a friction type clutch or the like.

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

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

[0023] The first timing belt 36a is stretched between the first drive pulley 37a and the first driven pulley 38a. The second timing belt 36b is stretched between the second drive pulley 37b and the second driven pulley 38b. The first and second timing belts 36a, 36b may be a chain instead of a belt. In addition, the power transmission between the first drive pulley 37a and the first driven pulley 38a, and the power transmission between the first drive pulley 37a and the first driven pulley 38a may be performed by gears such as a gear.

[0024] The first drive pulley 37a is arranged coaxially with the first axis of rotation 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 the torque transmitted from the first drive motor 26a. Also, the second drive pulley 37b is arranged coaxially with the second axis of rotation A2 of the pressurizing motor unit 27. The second drive pulley 37b is connected to the output shaft of the speed reducer 27b via the clutch 29 and rotates by the torque transmitted from the speed reducer 27b (driving rotating body).

[0025] The first and second driven pulleys 38a and 38b are arranged coaxially with the third axis of rotation A3 of the ball screw mechanism 55 and are connected to the ball screw nut 56 of the ball screw mechanism 55. The first and second driven pulleys 38a and 38b may be separate structures, or may be an integrated 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 decelerates the rotation of the second drive pulley 37b by a factor of Dd / Df and transmits it to the ball screw nut 56 (driven rotating body). 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 as it is. However, the diameter of the first driven pulley 38a may be different from the diameter of the first drive pulley 37a, and the first driven pulley 38a may decelerate or accelerate the rotation of the first drive pulley 37a and transmit it.

[0026] The ball screw mechanism 55 is a conversion mechanism that moves the upper table 7 in the vertical direction by converting the rotational motion by the torque of the rotational power unit 25 into a linear motion. The ball screw mechanism 55 includes a ball screw nut 56 and a ball screw shaft 57. The ball screw nut 56 is supported inside the housing of the ball screw mechanism 55 via a bearing portion. The ball screw nut 56 is connected to the driven pulley 38 of the power transmission mechanism 35 and rotates in response to the rotation of the driven pulley 38. The ball screw shaft 57 is screwed into the ball screw nut 56 and moves in the vertical direction as the ball screw nut 56 rotates forward and backward.

[0027] At the lower end of the ball screw mechanism 55, specifically at the lower end of the ball screw shaft 57, a connection block 60 is connected. At the lower end of the connection block 60, a suspension bolt 61 that hangs vertically along the vertical direction is attached, and the suspension bolt 61 supports a support shaft 62 that penetrates the upper table 7 in the front-rear direction. The ball screw shaft 57 is connected to the upper table 7 via the connection block 60 including the suspension bolt 61 and the support shaft 62.

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

[0029] The control device 100 is constituted 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. By causing the hardware processor to execute a program stored in the memory, various functions provided in the control device 100 are realized.

[0030] The control device 100 controls the rotational power unit 25. The control device 100 has a switchable operation mode including a high-speed mode and a high-torque mode. The high-speed mode is an operation mode in which the upper table 7 is moved by driving the high-speed motor unit 26 with the torque blocked by the clutch 29. The high-torque mode is an operation mode in which the upper table 7 is moved by driving the pressurizing motor unit 27 with the torque transmitted by the clutch 29.

[0031] Next, the control of the press brake 1 for bending the workpiece will be described. When processing the workpiece using the press brake 1, first, the workpiece is 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 in the released state. That is, the transmission of torque from the pressurizing motor unit 27 to the power transmission mechanism 35 is blocked.

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

[0033] When the upper table 7 moves to a predetermined low-speed switching position (approach position), the control device 100 stops the high-speed motor unit 26. The control device 100 switches the clutch 29 to the transmission state. As a result, the state in which torque is transmitted from the pressurizing motor unit 27 to the power transmission mechanism 35 is achieved. The control device 100 drives the pressurizing motor unit 27 in the rotational direction when moving the upper table 7 downward. As a result, the output shaft of the pressurizing motor unit 27 that outputs high torque at low speed rotates, and the upper table 7 descends at low speed (high-torque mode).

[0034] As one of the features of the present embodiment, when the control device 100 moves the upper table 7 downward in the high-torque mode, reverse control is performed to drive the high-speed motor unit in the direction opposite to the rotational direction when moving the upper table 7 downward. The details of the reverse control will be described later.

[0035] The control device 100 controls the pressurizing motor unit 27 and stops the upper table 7 in accordance with a predetermined lower end position (stroke position). In the process of the upper table 7 reaching the lower end position, the workpiece is pressurized between the upper die P and the lower die D and bent to a desired angle.

[0036] Next, the control device 100 drives the pressure motor unit 27 in the rotational direction when moving the upper table 7 upward. As a result, the upper table 7 rises 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 the released state. As a result, torque transmission from the pressure motor unit 27 to the power transmission mechanism 35 is blocked.

[0038] The control device 100 drives the high-speed motor unit 26 in the rotational direction when moving the upper table 7 upward. As a result, the output shaft of the high-speed motor unit 26 rotates, and the upper table 7 rises at high speed. When the upper table 7 moves to the upper end position, the control device 100 stops the high-speed motor unit.

[0039] In the press brake 1, bending processing of the workpiece is performed through such a series of steps. Hereinafter, the operation of the reverse control will be described.

[0040] In the process of the upper table 7 descending in the high-torque mode, while the workpiece is being pressed between the upper die P and the lower die D, the upper table 7 decelerates in order to stop at the lower end position. When the upper table 7 starts moving from the low-speed switching position and descends at a constant speed, a torque (negative torque) in the direction of pushing the upper table 7 downward acts on the second drive motor 27a. As it 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] Figures 4 and 5 conceptually show gear elements (mechanical elements) T1 and T2 that transmit torque in the speed reducer 27b and the clutch 29. The figure depicts the main parts of the axially rotating gear elements T1 and T2, and the rotational directions of the gear elements T1 and T2 correspond to the left - right direction of the paper surface. Among the gear elements T1 and T2, the gear element T1 is a gear element connected to the second drive pulley 37b side, and the gear element T2 is a gear element connected to the second drive motor 27a side.

[0042] A gap is intentionally provided between the gear elements T1 and T2 for the machine to move smoothly. In Figures 4 and 5, the gap is depicted as a left - right direction space between the teeth. If only the frictional force of the gear elements T1 and T2 cannot support the upper table 7, which is a heavy object, the gear element T1 will rotate by a small amount ΔG, and the upper table 7 will move downward. Therefore, even if the control device 100 stops the pressurizing motor unit 27 in accordance with the lower end position, there will be a problem that the upper table 7 will deviate from the lower end position.

[0043] In high - load bending processes such as bending of thick plates, a high bending reaction force acts on the upper table 7 from the workpiece, so the bending reaction force acts in the direction of supporting the self - weight of the upper table 7. Therefore, the phenomenon of unstable positioning of the upper table 7 occurs significantly in low - load bending processes such as bending of thin plates. In addition, such a phenomenon may also occur in offset bending processes where one of the left and right table drive devices 20 is under low load.

[0044] In view of such an event, when the control device 100 moves the upper table 7 downward in the high torque mode, it performs reverse control in a state where torque is transmitted by the clutch 29. By performing the reverse control, since the high-speed motor unit 26 is driven in the direction opposite to that of the pressurizing motor unit 27, the rotation R1 in the direction opposite to the rotation R2 of the gear element T2 acts on the gear element T1. As a result, the state where the gear element T2 continuously presses the gear element T1 is maintained until the upper table 7 reaches the lower end position. Since the minute movement of the gear element T1 is suppressed, it is possible to suppress the upper table 7 from moving downward. Therefore, the upper table 7 is accurately positioned with respect to the lower end position. Since the positioning of the upper table 7 is stabilized, it is possible to improve the processing accuracy.

[0045] Note that the minute movement of the gear element T1 occurs during the deceleration period in which the upper table 7 is decelerated. Therefore, the period during which the reverse control is performed may include at least the deceleration period. For example, the control device 100 may start the reverse control in accordance with the deceleration start timing of the upper table 7, or may start the reverse control a certain time before the deceleration start timing.

[0046] Also, as described above, an event in which the positioning of the upper table 7 becomes unstable significantly occurs in bending processing at a low load such as bending processing of a thin plate. Therefore, the control device 100 may perform reverse control when the load for bending the work is lower than a predetermined threshold value, such as in low-load bending. Thereby, appropriate control can be performed with respect to a situation where the positioning of the upper table 7 becomes unstable.

[0047] In the case of high-load bending where the load for bending the work is equal to or higher than the threshold value, the above-described reverse control is unnecessary. On the other hand, the control device 100 may perform assist control for driving the high-speed motor unit 26 in the rotation direction when the upper table 7 is moved downward. Thereby, since the pressing force by the upper table 7 can be increased, bending processing can also be performed on a work that requires a high load.

[0048] As described above, the press brake 1 according to this embodiment includes an upper table 7 disposed to face the lower table 5 in the vertical direction, a rotational power unit 25 that generates torque, a ball screw mechanism 55 that converts the rotational motion due to the torque of the rotational power unit 25 into a linear motion along the vertical direction to move the upper table 7 in the vertical direction, and a control device 100 that controls the rotational power unit 25 to bend a workpiece by molds P and D respectively mounted on the lower table 5 and the upper table 7. The rotational power unit 25 includes a high-speed motor unit 26, a pressurizing motor unit 27 that outputs high torque at a lower rotational 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 also transmits the torque of the pressurizing motor unit 27 to the ball screw mechanism 55, and a clutch 29. The power transmission mechanism 35 includes a second driving pulley 37b that rotates by the torque transmitted from the pressurizing motor unit 27, and a rotatable second driven pulley 38b connected to the ball screw mechanism 55, which has a diameter larger than the diameter of the second driving pulley 37b and decelerates and transmits the rotation of the second driving pulley 37b. The clutch 29 is disposed coaxially with the rotation axis A2 of the pressurizing motor unit 27 and selectively blocks the transmission of torque from the pressurizing motor unit 27 to the second driving pulley 37b. The control device 100 has, as a switchable operation mode, a high-speed mode in which the upper table 7 is moved by driving the high-speed motor unit 26 with the torque blocked by the clutch 29, and a high-torque mode in which the upper table 7 is moved by driving the pressurizing motor unit 27 with the 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 driving pulley 37b (see Fig. 3). Therefore, the second driven pulley 38b amplifies the torque of the pressurizing motor unit 27 by Df / Dd times and transmits it to the ball screw nut 56. In the power transmission path, the torque on the upstream side of the second driving pulley 37b is relatively smaller than the torque on the downstream side of the second driven pulley 38b. Since the clutch 29 is arranged closer to the pressurizing motor unit 27 than the second driving pulley 37b, even a small transmission capacity of the clutch 29 is sufficient. Therefore, an increase in the size of the clutch 29 can be suppressed, and consequently, an increase in the size of the press brake 1 itself can also be suppressed.

[0050] Also, according to the press brake 1 according to the present embodiment, by performing reverse control, the positioning of the upper table 7 with respect to the lower end position can be accurately performed. Since the positioning of the upper table 7 is stabilized, improvement in machining accuracy can be achieved.

[0051] When an engagement type clutch is adopted for the clutch 29, the gap between the teeth of the clutch is also transmitted to the ball screw mechanism 55. In the present embodiment, since the clutch 29 is arranged closer to the pressurizing motor unit 27 than the second driving pulley 37b, the gap is reduced by Dd / Df times and transmitted to the ball screw mechanism 55. Therefore, the positioning accuracy of the upper table 7 can be improved as compared with the case where the clutch 29 is provided on the downstream side of the second driven pulley 38b.

[0052] Further, in the present embodiment, the high-speed motor unit 26 includes a first drive motor 26a. The pressurizing motor unit 27 includes a second drive motor 27a and a speed reducer 27b that decelerates and outputs the rotation of the second drive motor 27a. According to this configuration, in addition to the deceleration by the power transmission mechanism 35, since the pressurizing motor unit 27 includes the speed reducer 27b, a high torque can be obtained at a low speed by the pressurizing motor unit 27.

[0053] In this embodiment, the high-speed motor unit 26 is composed of only the first drive motor 26a. However, as long as the high-speed motor unit 26 outputs low torque at a higher rotational speed than the pressurizing motor unit 27, it may include a speed reducer, similar to the pressurizing 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 pressurizing 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. According to this configuration, the reduction ratio can be set according to the ratio of the diameters of the second drive pulley 37b and the second driven pulley 38b. Thereby, the torque and speed can be set flexibly.

[0055] Also, since the high-speed motor unit 26 and the pressurizing motor unit 27 are not arranged vertically, the height of the machine can be suppressed.

[0056] (Second Embodiment) Hereinafter, the press brake 1 according to the second embodiment will be described. One of the features of the press brake 1 according to this second embodiment is the configuration of the rotational power unit 25 and the power transmission mechanism 35. Hereinafter, with reference to FIG. 6, the description will be centered on the differences from the first embodiment. 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 pressurizing motor unit 27 are arranged so as to face each other vertically with the power transmission mechanism 35 interposed therebetween. Specifically, the high-speed motor unit 26 is arranged above the power transmission mechanism 35, and the pressurizing motor unit 27 is arranged below the power transmission mechanism 35. The high-speed motor unit 26 and the pressurizing motor unit 27 are coaxially arranged along a common rotation axis A1. That is, the first drive motor 26a, the second drive motor 27a, and the speed reducer 27b are coaxially arranged along a 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 composed of a timing belt 36, a drive pulley 37, and a driven pulley 38.

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

[0060] Similar to the first embodiment, the diameter of the driven pulley 38 is set larger than the diameter of the drive pulley 37. Thereby, the driven pulley 38 decelerates the rotation of the drive pulley 37 and transmits it to the ball screw nut 56.

[0061] According to such a configuration, in the power transmission path, the torque acting on the upstream side of the drive pulley 37 is relatively smaller than the torque on the downstream side of the driven pulley 38. Since the clutch 29 is arranged on the side of the pressurizing motor unit 27 rather than the drive pulley 37, even a small transmission capacity of the clutch 29 is sufficient. Therefore, an increase in the size of the clutch 29 can be suppressed, and thus an increase in the size of the press brake 1 itself can be suppressed.

[0062] In addition, mechanical components such as the timing belt 36 and the drive pulley 37 can be shared between the high-speed motor unit 26 and the pressurizing motor unit 27. Thereby, while suppressing an increase in cost, the inertia in the mechanical elements can be reduced. Further, since the high-speed motor unit 26 and the pressurizing motor unit 27 are arranged side by side in the vertical direction, an expansion in the space in the left-right direction and the front-rear direction can be suppressed. Therefore, space saving of the machine can be realized.

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

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

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

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

Explanation of Reference Numerals

[0067] 1 Press brake 2 Side plate 5 Lower table (fixed table) 7 Upper table (movable table) 20 Table drive device 25 Rotational power unit 26 High-speed motor unit 26a First drive motor 27 Pressurizing motor unit 27a Second drive motor 27b Reducer 29 Clutch 35 Power transmission mechanism 36 Timing belt 36a First timing belt 36b Second timing belt 37 Drive pulley 37a First drive pulley 37b Second drive pulley (driving rotating body) 38 Driven pulley (driven rotating body) 38a First driven pulley (driven rotating body) 38b Second driven pulley (driven rotating body) 55 Ball screw mechanism (conversion mechanism) 56 Ball screw nut 57 Ball screw shaft 100 Control device

Claims

1. A movable table disposed to face the fixed table in the vertical direction, A rotational power unit that generates torque, A conversion mechanism that converts the rotational motion due to the torque of the rotational power unit into a linear motion along the vertical direction to move the movable table in the vertical direction, A control device that controls the rotational power unit to bend a workpiece by molds respectively mounted on the fixed table and the movable table, The rotational power unit is A high-speed motor unit, A pressurizing motor unit that outputs high torque at a lower rotational speed than the high-speed motor unit, A power transmission mechanism that transmits the torque of the high-speed motor unit to the conversion mechanism and transmits the torque of the pressurizing motor unit to the conversion mechanism, A clutch, The power transmission mechanism is A driving rotating body that rotates by the torque transmitted from the pressurizing motor unit, A rotatable driven rotating body connected to the conversion mechanism, having a diameter larger than that of the driving rotating body, and reducing and transmitting the rotation of the driving rotating body, The clutch is Disposed coaxially with the rotation axis of the pressurizing motor unit, selectively blocking the transmission of torque from the pressurizing motor unit to the driving rotating body, The control device is As a switchable operation mode, A high-speed mode in which the movable table is moved by driving the high-speed motor unit with the torque blocked by the clutch, A high-torque mode in which the movable table is moved by driving the pressurizing motor unit with the torque transmitted by the clutch, The transmission capacity of the clutch is larger than the torque transmitted from the pressurizing motor unit to the driving rotating body and smaller than the torque transmitted from the driven rotating body to the conversion mechanism, A bending machine.

2. The high-speed motor unit includes a first drive motor, The pressurizing motor unit includes a second drive motor and a speed reducer that decelerates and outputs the rotation of the second drive motor, The bending machine according to Claim 1.

3. The clutch is provided in the power transmission path from the second drive motor to the driving rotating body, The bending machine according to Claim 2.

4. The clutch is provided in the speed reducer, The bending machine according to Claim 2.

5. A movable table disposed opposite to the fixed table in the vertical direction, A rotational power unit that generates torque, A conversion mechanism that moves the movable table in the vertical direction by converting the rotational motion due to the torque of the rotational power unit into a linear motion along the vertical direction, A control device that bends a workpiece by molds respectively mounted on the fixed table and the movable table by controlling the rotational power unit, The rotational power unit includes A high-speed motor unit including a first drive motor, A pressurizing motor unit including a second drive motor and a speed reducer that decelerates and outputs the rotation of the second drive motor, A power transmission mechanism that transmits the torque of the high-speed motor unit to the conversion mechanism and transmits the torque of the pressurizing motor unit to the conversion mechanism, A clutch, The power transmission mechanism includes A driving rotating body that rotates by the torque transmitted from the speed reducer, A rotatable driven rotating body connected to the conversion mechanism, having a diameter larger than that of the driving rotating body, and transmitting the rotation of the driving rotating body after deceleration, The clutch is Provided in the power transmission path from the second drive motor to the driving rotating body, and selectively blocks the transmission of torque to the driving rotating body, The control device has As a switchable operation mode, A high-speed mode in which the movable table is moved by driving the high-speed motor unit with the torque blocked by the clutch, A high-torque mode in which the movable table is moved by driving the pressurizing motor unit with the torque transmitted by the clutch, The transmission capacity of the clutch is larger than the torque transmitted from the speed reducer to the driving rotating body and smaller than the torque transmitted from the driven rotating body to the conversion mechanism, A bending machine.

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

7. The power transmission mechanism includes A driving pulley as the driving rotating body to which the high-speed motor unit and the pressurizing motor unit are respectively connected, A driven pulley as the driven rotating body connected to the conversion mechanism, A belt stretched between the driving pulley and the driven pulley, The high-speed motor unit is coaxially disposed on the opposite side of the pressurizing motor unit across the driving pulley, The bending machine according to any one of claims 1 to 6.

8. The power transmission mechanism a first drive pulley to which the high-speed motor unit is connected; a second drive pulley as the drive rotating body to which the pressurization motor unit is connected; first and second driven pulleys as the driven rotating bodies, which are connected to the conversion mechanism; a first belt stretched between the first drive pulley and the first driven pulley; a second belt stretched between the second drive pulley and the second driven pulley, and includes The bending machine according to any one of claims 1 to 6.

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