Bending machine

Abstract

A control device (100) has, as switchable operation modes, a high-speed mode and a high-torque mode. The high-speed mode moves an upper table (7) by driving, in a state in which the torque of a pressurization motor unit (27) is blocked by a clutch (29), a high-speed motor unit (26) that outputs low torque at high-speed rotation. The high-torque mode moves the upper table (7) by driving, in a state in which the torque of the pressurization motor unit (27) is being transmitted by the clutch (29), the pressurization motor unit (27). When moving the upper table (7) downward in the high torque mode, the control device (100) performs inversion control in which the high-speed motor unit (26) is driven in the opposite direction from the rotation direction when the upper table (7) is moved downward.

Description

Bending machine

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

[0002] A press brake 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 rotational power unit and a conversion mechanism that converts rotational motion caused by the torque of the rotational power unit into linear motion along the up and down direction, thereby moving the movable table up and down.

[0003] Patent Document 1 discloses a variable torque motor including a motor body, a reducer using a paradox planetary gear mechanism, and a clutch provided between the motor body and the reducer. This variable torque motor can switch between a mode that produces high torque at low rotation speeds and a mode that produces low torque at high rotation speeds by selectively fixing the carrier and second internal gear of the paradox planetary gear mechanism with a clutch acting portion of the clutch.

[0004] Japanese Patent Application Laid-Open No. 2021-136855

[0005] In a structure in which torque is transmitted by mechanical elements such as gears, gaps are intentionally provided between the mechanical elements to ensure smooth operation of the mechanical elements, but these gaps cause slight movements of the mechanical elements, which can cause unstable positioning of the movable table and reduce machining accuracy.

[0006] One aspect of one or more embodiments relates to 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, respectively. The rotational power unit includes a high-speed motor unit, a pressure motor unit that outputs high torque at a rotation speed lower than that of 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 pressure motor unit to the conversion mechanism, and a clutch that can interrupt the transmission of torque from the pressure motor unit to the power transmission mechanism. The control device has 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; and when the movable table is moved downward in the high-torque mode, reversal control is performed in which the high-speed motor unit is driven in the direction opposite to the rotational direction when moving the movable table downward with torque transmitted by the clutch.

[0007] According to one or more embodiments of the bending machine, when the movable table is moved downward in high torque mode, the movement of the mechanical elements that transmit torque can be suppressed, thereby enabling stable positioning of the movable table.

[0008] According to one or more embodiments of the bending machine, the movable table can be positioned stably, thereby improving the processing accuracy.

[0009] 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 conceptual diagram showing gear elements (mechanical elements) that transmit torque. Fig. 4 is a conceptual diagram showing gear elements (mechanical elements) that transmit torque. Fig. 5 is a side view schematically showing a table drive device of a press brake according to a second embodiment.

[0010] Hereinafter, with reference to the drawings, a bending machine according to this embodiment will be described using a press brake as an example.

[0011] 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.

[0012] The press brake 1 according to this embodiment includes an upper table 7 disposed vertically opposite the lower table 5, a rotational power unit 25 that generates torque, a 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 a control device 100 that controls the rotational power unit 25 to perform bending processing on a workpiece using 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 rotates at a slower speed than the high-speed motor unit 26 but outputs high torque, 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 that can interrupt transmission of torque from the pressure motor unit 27 to the power transmission mechanism 35. 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 disconnected 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. 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 26 in the direction opposite to the rotation direction when moving the upper table 7 downward, with torque transmitted by the clutch 29.

[0013] Hereinafter, the press brake 1 will be described in detail with reference to FIGS. 1 and 2.

[0014] 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.

[0015] The left and right side plates 2 are arranged opposite each other and spaced apart in the left-right direction.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] The high-speed motor unit 26 is made up 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.

[0021] The pressure motor unit 27 is composed of a second drive motor 27a and a reducer 27b. The first drive motor 26a is a device that generates torque using electrical energy, such as a servo motor. The reducer 27b reduces the rotational power (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.

[0022] The clutch 29 transmits or blocks torque from the pressure motor unit 27 to the power transmission mechanism 35. The clutch 29 is a tooth clutch that transmits torque by meshing teeth, but is not limited to this.

[0023] The clutch 29 is disposed between the reducer 27b of the pressure motor unit 27 and a drive pulley 37 of the power transmission mechanism 35, which will be 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 drive pulley 37. On the other hand, when the teeth of the clutch 29 are not engaged (release state), the clutch 29 blocks the transmission of torque from the output shaft of the reducer 27b to the drive pulley 37.

[0024] The clutch 29 is not limited to the above-described configuration as long as it is provided on the power transmission path from the second drive motor 27a to the drive pulley 37. For example, the clutch 29 may be interposed between the second drive motor 27a and the reducer 27b.

[0025] The power transmission mechanism 35 transmits the torque of the rotational power unit 25 to the ball screw mechanism 55. That is, the power transmission mechanism 35 transmits the torque of the high-speed motor unit 26 to the ball screw mechanism 55, and also transmits the torque of the pressure motor unit 27 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.

[0026] 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 the high-speed motor unit 26, i.e., the drive shaft of the first drive motor 26a. The drive pulley 37 is also connected to the output shaft of the pressure motor unit 27, i.e., the output shaft of the reducer 27b, via a clutch 29. A ball screw nut 56 of a ball screw mechanism 55, which will be described later, is connected to the driven pulley 38.

[0027] In this embodiment, the high-speed motor unit 26 is arranged coaxially on the opposite side of the pressure motor unit 27 with the drive pulley 37 in between. Specifically, the high-speed motor unit 26 is arranged above the drive pulley 37, and the pressure motor unit 27 is arranged below the drive pulley 37. The first drive motor 26a, the second drive motor 27a, the reducer 27b, and the clutch 29 are each arranged coaxially.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 (drive shaft of the first drive motor 26a) of the high-speed motor unit 26, which outputs low torque at high speed, and the upper table 7 descends at high speed (high-speed mode).

[0035] 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 (output shaft of the reducer 27b) 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).

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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 (drive shaft of the first drive motor 26a) 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.

[0041] The workpiece is bent through a series of steps in the press brake 1. The operation of the reversal control will now be described.

[0042] 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.

[0043] 3 and 4 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 drive pulley 37 side, and the gear element T2 is the gear element connected to the second drive motor 27a side.

[0044] A gap is intentionally provided between the gear elements T1 and T2 to allow the machine to operate smoothly. In Figures 3 and 4, 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. Therefore, 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] As described above, according to the press brake 1 of this embodiment, by performing the reversal control, it is possible to accurately position the upper table 7 relative to the lower end position. Since the positioning of the upper table 7 is stable, it is possible to improve the processing accuracy.

[0051] 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 torque of the second drive motor 27a and outputs it. With this configuration, the pressure motor unit 27 includes the reducer 27b, so that the pressure motor unit 27 can obtain high torque at a low rotation speed.

[0052] 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.

[0053] In this embodiment, the power transmission mechanism 35 includes a drive pulley 37 to which the high-speed motor unit 26 and the pressure motor unit 27 are respectively connected, a driven pulley 38 connected to the ball screw mechanism 55, and a timing belt 36 stretched between the drive pulley 37 and the driven pulley 38. In this case, the high-speed motor unit 26 is coaxially arranged on the opposite side of the drive pulley 37 from the pressure motor unit 27.

[0054] This configuration allows the high-speed motor unit 26 and the pressure motor unit 27 to 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.

[0055] 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. 5. Fig. 5 is a side view schematically showing the table drive device 20 of the press brake 1 according to the second embodiment.

[0056] In this embodiment, the high-speed motor unit 26 and the pressure motor unit 27 are arranged on separate shafts. The high-speed motor unit 26 is arranged with its output shaft (the drive shaft of the first drive motor 26 a) facing upward, and the pressure motor unit 27 is also arranged with its output shaft (the output shaft of the reducer 27 b) facing upward.

[0057] The power transmission mechanism 35 is made up of a first timing belt 36 a, a second timing belt 36 b, a first driving pulley 37 a, a second driving pulley 37 b, and a driven pulley 38 .

[0058] The first timing belt 36a is stretched between the first driving pulley 37a and the driven pulley 38. The second timing belt 36b is stretched between the second driving pulley 37b and the driven pulley 38.

[0059] The first drive pulley 37a is connected to the output shaft of the high-speed motor unit 26, i.e., the drive shaft of the first drive motor 26a. The second drive pulley 37b is connected to the output shaft of the pressure motor unit 27, i.e., the output shaft of the reducer 27b, via the clutch 29. The driven pulley 38 is connected to a ball screw nut 56 of a ball screw mechanism 55.

[0060] With this configuration, the reduction ratio can be set in accordance with the ratio of the pulley diameters of the first drive pulley 37a and the driven pulley 38. This allows for flexible setting of torque and speed.

[0061] 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.

[0062] 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.

[0063] 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, examples and operating techniques will become apparent to those skilled in the art from this embodiment.

[0064] 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 system 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 to move the movable table vertically; and a control device which controls the rotational power unit to perform bending processing on a workpiece using dies attached to the fixed table and the movable table, respectively; the rotational power unit comprises: 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 which can interrupt the transmission of torque from the pressure motor unit to the power transmission mechanism; and 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 interrupted 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; a rotational direction of the high-speed motor unit that is rotated in a direction opposite to the rotational direction of the movable table when the movable table is moved downward in the high-torque mode; 2. The bending machine according to claim 1, wherein the control device performs the reversal control in the case of low-load bending in which the load for bending the workpiece is lower than a predetermined threshold value.

3. A bending machine as described in claim 2, wherein the control device performs assist control to drive the high-speed motor unit in the rotational direction when moving the movable table downward when the load applied to the workpiece is high-load bending that is equal to or greater than the threshold value.

4. A bending machine as claimed in any one of claims 1 to 3, 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 torque of the second drive motor and outputs it.

5. A bending machine as claimed in any one of claims 1 to 3, wherein the power transmission mechanism includes a drive pulley to which the high-speed motor unit and the pressure motor unit are respectively connected, a driven pulley 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.

6. A bending machine as claimed in any one of claims 1 to 3, wherein the power transmission mechanism includes: a first drive pulley to which the high-speed motor unit is connected; a second drive pulley to which the pressure motor unit is connected; a driven pulley connected to the conversion mechanism; a first belt stretched between the first drive pulley and the driven pulley; and a second belt stretched between the second drive pulley and the driven pulley.

Images