Press brake

Abstract

To accurately position an upper table of a press brake.SOLUTION: A fixed clutch member 46 causes a speed reducer 31 to operate at a second gear reduction ratio larger than a first gear reduction ratio when engaged with a first clutch member 47. Respective tip surfaces A3 of a plurality of first anchor teeth 46a in the fixed clutch member 46 are formed to be a taper surface inclined in the circumferential direction. A tooth groove bottom surface B4 existing between first clutch teeth 47a in the first clutch member 47 is formed to be a taper surface along the tip surface A3 of the first anchor tooth 46a. A height of one of tooth side surfaces B1 of the first clutch tooth 47a is formed larger than a height of the other tooth side surface B2. The one tooth side surface B1 is positioned on a side pressing the first fixed tooth 46a when pressurizing a workpiece between an upper die and a lower die.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a press brake. [Background technology]

[0002] A press brake performs bending on a workpiece by moving an upper table, on which a punch is attached, up and down relative to a lower table, on which a die is attached. The press brake is equipped with a table drive device that moves the upper table up and down using a drive motor. The table drive device moves the upper table up and down by transmitting power output from the drive motor.

[0003] Patent Document 1 discloses a technique in which a ball screw mechanism is rotated by a rotary drive source to move an upper table in the vertical direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5531878 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional press brakes have had the problem that it is difficult to position the upper table accurately due to the gaps that exist between the elements of the power transmission mechanism. [Means for solving the problem]

[0006] One aspect of one or more embodiments is an upper table to which an upper die for bending a workpiece in cooperation with a lower die is attached, a speed reducer that reduces the rotation of a drive motor and outputs it at a reduction ratio of either a first reduction ratio or a second reduction ratio greater than the first reduction ratio, a conversion mechanism that moves the upper table in the vertical direction by converting the rotational motion that is the output of the speed reducer into a linear motion, and a clutch unit that switches the reduction ratio of the speed reducer between the first reduction ratio and the second reduction ratio. The clutch unit includes an annular first clutch member provided with a plurality of first clutch teeth along the circumferential direction, an annular second clutch member provided with a plurality of second clutch teeth along the circumferential direction so as to face the plurality of first clutch teeth, and an annular fixed clutch member provided movably in the axial direction between the first clutch member and the second clutch member and provided with a plurality of first fixed teeth engageable with the plurality of first clutch teeth and a plurality of second fixed teeth engageable with the plurality of second clutch teeth along the circumferential direction. The fixed clutch member operates the speed reducer at the first reduction ratio by engaging with the second clutch member and operates the speed reducer at the second reduction ratio by engaging with the first clutch member. The tip surface of each of the plurality of first fixed teeth is formed on a tapered surface inclined with respect to the circumferential direction. A bottom surface of a tooth groove against which the tip surface of the first fixed tooth abuts is provided between adjacent first clutch teeth, and the bottom surface of the tooth groove is formed on a tapered surface along the tip surface of the first fixed tooth. The height of one tooth side surface in the circumferential direction of the first clutch tooth is formed to be greater than the height of the other tooth side surface in the circumferential direction of the first clutch tooth. One tooth side surface is located on the side that presses the first fixed tooth when pressing the workpiece between the upper die and the lower die.

Effect of the Invention

[0007] According to the press brake according to one or more embodiments, the upper table can be accurately positioned.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1 is a front view showing the press brake according to the present embodiment. [Figure 2]FIG. 2 is a cross-sectional view showing the main part of the speed reducer unit. [Figure 3] FIG. 3 is a side view showing a part of the clutch portion enlarged. [Figure 4] FIG. 4 is a side view for explaining the tooth structure of the clutch portion. [Figure 5] FIG. 5 is a view showing the state of the clutch portion when switching to the high torque mode. [Figure 6] FIG. 6 is a view showing the state of the clutch portion when the workpiece is pressed. [Figure 7] FIG. 7 is a view for explaining the relationship of the forces acting on the clutch portion. [Figure 8] FIG. 8 is a view for explaining the relationship of the forces acting on the clutch portion.

MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, with reference to the drawings, the press brake according to this embodiment will be described. In this specification, as definitions of directions, the left - right direction, the front - rear direction, and the up - down direction are used. The left - right direction and the front - rear direction correspond to two orthogonal directions in the horizontal direction, and the up - down direction corresponds to the vertical direction. These directions are merely used for convenience in explaining the press brake according to this embodiment.

[0010] FIG. 1 is a front view showing the press brake 1 according to this embodiment. 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, an upper table 7, left and right table driving devices 20, and a control device 100.

[0011] The left and right side plates 2 are arranged at a distance from each other in the left - right direction so as to face each other.

[0012] The lower table 5 extends in the left - right direction. The lower table 5 is supported at the lower front sides of the left and right side plates 2. On the upper side of the lower table 5, a lower die holder 6 for detachably holding the lower die D is provided along the left - right direction.

[0013] The upper table 7 extends in the left - right direction. The upper table 7 is supported at the upper front sides of the left and right side plates 2 and is disposed above the lower table 5. The upper table 7 is supported by the left and right side plates 2 so as to be movable in the vertical direction. On the lower side of the upper table 7, an upper die holder 8 for detachably holding the upper die P is provided along the left - right direction. That is, the upper die P that cooperates with the lower die D to bend the work is mounted on the upper table 7.

[0014] The left and right table driving devices 20 are 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. The table driving device 20 mainly comprises a driving motor 25, a speed - reducer unit 30, and a ball - screw mechanism 55.

[0015] The driving motor 25 is a driving source driven by electric energy and includes a motor shaft 26 (see FIG. 2) that rotates around an axis. The driving motor 25 is, for example, a servo motor.

[0016] The speed - reducer unit 30 includes an output shaft 41 (see FIG. 2) that rotates in response to the rotation of the motor shaft 26 of the driving motor 25. The rotation of the output shaft 41 is decelerated at a predetermined reduction ratio with respect to the rotation of the motor shaft 26. The speed - reducer unit 30 is a part of the power - transmission mechanism that transmits the power output from the driving motor, and its details will be described later.

[0017] The ball screw mechanism 55 is a conversion mechanism that moves the upper table 7 in the vertical direction by converting the rotational motion of the output shaft 41 of the speed reducer unit 30 into 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 output shaft 41 of the drive unit 24 and rotates in response to the rotation of the output shaft 41. 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.

[0018] 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 that hangs down along 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 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.

[0019] A control device 100 such as an NC (Numerical Control) device that controls the operation of the press brake 1 is supported on the left side plate 2 via a connection arm. The control device 100 controls the left and right table drive devices 20.

[0020] FIG. 2 is a cross-sectional view showing the main part of the speed reducer unit 30. The speed reducer unit 30 is composed of a speed reducer 31 and a clutch portion 45. The speed reducer 31 reduces the rotation of the motor shaft 26 to either a first reduction ratio or a second reduction ratio that is larger than the first reduction ratio and outputs it to the output shaft 41. The clutch portion 45 switches the reduction ratio of the speed reducer 31 between the first reduction ratio and the second reduction ratio.

[0021] The speed reducer 31 includes a mysterious planetary gear mechanism. Specifically, the speed reducer 31 includes a sun gear 32, a plurality of planetary gear units 33, a planetary carrier 34, a first internal gear 38, a second internal gear 40, and an output shaft 41.

[0022] The sun gear 32 is externally fitted onto the outer peripheral surface of the motor shaft 26. The sun gear 32 rotates integrally with the motor shaft 26.

[0023] A plurality of planetary gear units 33 are provided around the sun gear 32 and are arranged at equal intervals in the circumferential direction. Each planetary gear unit 33 is composed of a first planetary gear 33a and a second planetary gear 33b. The first planetary gear 33a meshes with the sun gear 32 and rotates due to the rotation of the sun gear 32. The second planetary gear 33b is provided coaxially with the first planetary gear 33a and rotates integrally with the first planetary gear 33a. In the present embodiment, the first planetary gear 33a and the second planetary gear 33b have a two-stage structure integrated in the vertical direction, and the first planetary gear 33a and the second planetary gear 33b rotate on the same axis.

[0024] The planetary carrier 34 rotates around the motor shaft 26 via a bearing portion 35 externally fitted onto the motor shaft 26 and the like. A plurality of unit shafts 36 are provided on the planetary carrier 34 along the circumferential direction. A bearing portion 37 is externally fitted onto each unit shaft 36, and the planetary gear unit 33 is attached via the bearing portion 37. The planetary carrier 34 supports each of the plurality of planetary gear units 33 so as to be rotatable.

[0025] The first internal gear 38 is an internal gear that meshes with the first planetary gear 33a. The first internal gear 38 is provided on the inner peripheral surface of the housing of the speed reduction unit 30 via a bearing portion 39 and can rotate around the motor shaft 26.

[0026] The second internal gear 40 has a different number of teeth from the first internal gear 38 and is an internal gear that meshes with the second planetary gear 33b. The second internal gear 40 is provided on the inner peripheral surface of the housing of the speed reduction unit 30 via a bearing portion 42 and can rotate around the motor shaft 26.

[0027] The output shaft 41 is integrally formed with the second internal gear 40 and rotates integrally with the second internal gear 40. The output shaft 41 is connected to the ball screw nut 56 of the ball screw mechanism 55 described above.

[0028] The clutch portion 45 includes a fixed clutch member 46, a first clutch member 47, and a second clutch member 48. The fixed clutch member 46, the first clutch member 47, and the second clutch member 48 are each annular members and have a tooth structure as described later. The first clutch member 47 and the second clutch member 48 are arranged vertically opposite to each other so that their tooth structures face each other. The fixed clutch member 46 is provided between the first clutch member 47 and the second clutch member 48.

[0029] FIG. 3 is a side view showing a partially enlarged view of the clutch portion 45. The fixed clutch member 46 is movable in the vertical direction (axial direction) and moves between the first clutch member 47 and the second clutch member 48. The fixed clutch member 46 is restricted from moving in directions other than the vertical direction. That is, the fixed clutch member 46 is restricted from rotating in the circumferential direction and can only move in the vertical direction.

[0030] The first clutch member 47 is connected to the first internal gear 38 (see FIG. 2) included in the speed reducer 31 and rotates integrally with the first internal gear 38. A plurality of first clutch teeth 47a are provided on the first clutch member 47 along the circumferential direction. Each of the first clutch teeth 47a protrudes toward the fixed clutch member 46 side.

[0031] The second clutch member 48 is connected to the planetary carrier 34 (see FIG. 2) included in the speed reducer 31 and rotates integrally with the planetary carrier 34. A plurality of second clutch teeth 48a are provided on the second clutch member 48 in the circumferential direction. Each of the individual second clutch teeth 48a protrudes toward the fixed clutch member 46 side.

[0032] The fixed clutch member 46 is provided with a plurality of first fixed teeth 46a in the circumferential direction and a plurality of second fixed teeth 46b in the circumferential direction. Each of the first fixed teeth 46a protrudes toward the first clutch member 47 side and is configured to be engageable with the first clutch teeth 47a of the first clutch member 47. Each of the second fixed teeth 46b protrudes toward the second clutch member 48 side and is configured to be engageable with the second clutch teeth 48a of the second clutch member 48.

[0033] One of the features of the present embodiment lies in the tooth structure between the fixed clutch member 46 and the first clutch member 47, the details of which will be described later.

[0034] As shown in FIG. 2, the clutch portion 45 includes a pressing member (not shown) and a solenoid 49. The pressing member is, for example, a compression coil spring, and presses the fixed clutch member 46 toward the first clutch member 47 side. That is, since the fixed clutch member 46 receives the pressing force of the pressing member, it normally moves toward the first clutch member 47 side. On the other hand, the solenoid 49 moves the fixed clutch member 46 by adsorbing with electromagnetic force. By operating the solenoid 49 and adsorbing with electromagnetic force, the fixed clutch member 46 moves toward the second clutch member 48 side against the pressing force of the pressing member.

[0035] The speed reducer unit 30 has two switchable operation modes. The two operation modes are a high torque mode and a high speed mode.

[0036] The high torque mode is a mode in which the fixed clutch member 46 engages with the first clutch member 47. When the fixed clutch member 46 engages with the first clutch member 47, the first clutch member 47 is fixed, so the rotation of the first internal gear 38 is restricted. In this case, the speed reducer 31 operates at a second reduction ratio larger than the first reduction ratio.

[0037] The high-speed mode is a mode in which the fixed clutch member 46 engages with the second clutch member 48. When the fixed clutch member 46 engages with the second clutch member 48, the second clutch member 48 is fixed, so the rotation of the planetary carrier 34 is restricted. In this case, the speed reducer 31 operates at the first reduction ratio.

[0038] Hereinafter, with reference to FIGS. 1 and 2, the lift control of the upper table 7 for bending a workpiece will be described. When processing a workpiece using the press brake 1, first, the workpiece is positioned on the lower die D. At this time, the upper table 7 is supported at a predetermined upper end position P1.

[0039] The control device 100 causes the solenoid 49 to perform an attracting operation. Since the fixed clutch member 46 moves toward the second clutch member 48 side, the speed reducer unit 30 enters the high-speed mode in which the fixed clutch member 46 engages with the second clutch member 48.

[0040] The control device 100 rotates the motor shaft 26 forward. In the high-speed mode, the planetary carrier 34 is fixed, but the first internal gear 38 is released. Since the planetary carrier 34 is fixed, the first planetary gear 33a meshing with the first internal gear 38 rotates together with the sun gear 32 rotating integrally with the motor shaft 26 without revolving. On the other hand, the rotation of the first planetary gear 33a also rotates the second planetary gear 33b integral with it, so the second internal gear 40 also rotates due to the rotation of the second planetary gear 33b. As a result, the output shaft 41 coupled to the second internal gear 40 also rotates synchronously. At this time, the rotation of the motor shaft 26 is output to the output shaft 41 as a simple planetary gear mechanism without being decelerated by the wonder planetary gear mechanism. That is, the reduction ratio of the speed reducer 31 becomes the first reduction ratio. Therefore, the output shaft 41 rotates in a high-speed and low-torque state, and the upper table 7 descends at high speed.

[0041] When the upper table 7 descends to the low-speed switching position P2, the control device 100 stops the rotation of the motor shaft 26. Thereafter, the control device 100 ends the adsorption operation of the solenoid 49. As a result, the fixed clutch member 46 moves toward the first clutch member 47, so that the speed reducer unit 30 enters a high-torque mode in which the fixed clutch member 46 engages with the first clutch member 47.

[0042] The control device 100 rotates the motor shaft 26 in the reverse direction. In the high-torque mode, the first internal gear 38 is fixed, but the planetary carrier 34 is released. Therefore, the first planetary gear 33a meshing with the first internal gear 38 revolves around the sun gear 32 that rotates integrally with the motor shaft 26 while rotating on its own. The rotation of the first planetary gear 33a also rotates the second planetary gear 33b integral with it, so that the rotation of the second planetary gear 33b also rotates the second internal gear 40 having a different number of teeth from the first internal gear 38. As a result, the output shaft 41 coupled to the second internal gear 40 also rotates synchronously. At this time, the rotation of the motor shaft 26 is greatly decelerated by the wonderful planetary gear mechanism and output to the output shaft 41. That is, the reduction ratio of the speed reducer 31 becomes a second reduction ratio larger than the first reduction ratio. Therefore, the output shaft 41 rotates in a low-speed and high-torque state, and the upper table 7 descends at a low speed.

[0043] When the upper table 7 reaches a predetermined lower end position (stroke position) P3, the control device 100 stops the reverse rotation of the motor shaft 26 and maintains a stopped state for a certain period. The workpiece is bent to a desired angle by being pressed between the upper mold P and the lower mold D.

[0044] Next, the control device 100 rotates the motor shaft 26 in the forward direction. At this time, the rotation of the motor shaft 26 is greatly decelerated by the wonderful planetary gear mechanism and output to the output shaft 41. As a result, the upper table 7 rises at a low speed.

[0045] When the upper table 7 rises to a predetermined high-speed switching position P4, the control device 100 stops the rotation of the motor shaft 26. Then, the control device 100 activates the solenoid 49 for adsorption operation. As a result, since the fixed clutch member 46 moves toward the second clutch member 48, the speed reducer unit 30 enters a high-speed mode in which the fixed clutch member 46 engages with the second clutch member 48.

[0046] The control device 100 rotates the motor shaft 26 in the reverse direction. At this time, the rotation of the motor shaft 26 is output to the output shaft 41 as a simple planetary gear mechanism without being decelerated by the fantastic planetary gear mechanism. As a result, the upper table 7 rises at high speed. When the upper table 7 moves to the upper end position P1, the control device 100 stops the rotation of the motor shaft 26 and ends the adsorption operation of the solenoid 49.

[0047] As described above, through a series of controls for the table drive device 20, the workpiece is bent by the cooperation of the upper die P and the lower die D.

[0048] Next, referring to FIGS. 3 and 4, the tooth structure of the fixed clutch member 46 and the first clutch member 47, which is one of the features of the present embodiment, will be described. FIG. 4 is a side view for explaining the tooth structure of the clutch portion 45.

[0049] As shown in FIG. 3, a plurality of first fixed teeth 46a are provided at regular intervals along the circumferential direction of the fixed clutch member 46. As shown in FIG. 4, the first fixed tooth 46a includes a tooth side surface A1 on one side in the circumferential direction and a tooth side surface A2 on the other side in the circumferential direction. The bottom surface A4 of the tooth groove located between adjacent first fixed teeth 46a is formed in a planar shape parallel to the circumferential direction.

[0050] The tip surface A3 of the first fixed tooth 46a is formed as a tapered surface that is inclined with respect to the circumferential direction. In the example shown in FIG. 4, the tip surface A3 is formed to slope downward toward the left side in the figure. Due to this tapered surface, the height of one tooth side surface A1 of the first fixed tooth 46a is formed smaller than the height of the other tooth side surface A2.

[0051] As shown in FIG. 3, a plurality of first clutch teeth 47a are provided at regular intervals along the circumferential direction of the first clutch member 47. As shown in FIG. 4, the first clutch teeth 47a include a tooth side surface B1 on one side in the circumferential direction and a tooth side surface B2 on the other side in the circumferential direction. The tip surface B3 of the first clutch tooth 47a is formed in a planar shape parallel to the circumferential direction.

[0052] Between adjacent first clutch teeth 47a, the tip surface A3 of the first fixed tooth 46a abuts, and a tooth groove bottom surface B4 is provided. This tooth groove bottom surface B4 is formed as a tapered surface along the tip surface A3 of the first fixed tooth 46a, that is, a tapered surface inclined with respect to the circumferential direction. In the example shown in FIG. 4, the tooth groove bottom surface B4 is formed to slope downward toward the left side in the drawing. Due to this tapered surface, the height of one tooth side surface B1 of the first clutch tooth 47a is formed larger than the height of the other tooth side surface B2. This one tooth side surface B1 is located on the side that presses the first fixed tooth 46a when the upper table 7 is pressed toward the lower table 5, that is, when the workpiece is pressed between the upper mold P and the lower mold D.

[0053] According to the fixed clutch member 46 and the first clutch member 47 having such a tooth structure, the following effects can be obtained.

[0054] The fixed clutch member 46 moves toward the first clutch member 47 when pressed by a pressing member. As shown in FIG. 4, the fixed clutch member 46 enters the high torque mode by engaging with the first clutch member 47.

[0055] The interval of the tooth grooves, which is the gap between adjacent first clutch teeth 47a, is set larger than the circumferential tooth width of the first fixed tooth 46a. This is to smoothly switch the fixed clutch member 46. For this reason, when switching to the high torque mode, gaps exist between each tooth side surface A1, A2 of the first fixed tooth 46a and the first clutch teeth 47a on both sides thereof.

[0056] FIG. 5 is a diagram showing the state of the clutch portion 45 when switching to the high torque mode. When the fixed clutch member 46 moves to the first clutch member 47, the tip surface A3 of the first fixed tooth 46a abuts against the bottom surface B4 of the tooth groove of the first clutch member 47. The fixed clutch member 46 is pressed against the first clutch member 47 by the force Fs applied from the pressing member. The tip surface A3 of the first fixed tooth 46a and the bottom surface B4 of the tooth groove of the first clutch member 47 are each formed as tapered surfaces. The force Fs received by the bottom surface B4 of the tooth groove of the first clutch member 47 from the tip surface A3 of the first fixed tooth 46a is divided into a component force Fsh parallel to the tapered surface and a component force Fsv perpendicular to the tapered surface.

[0057] When the component force Fsh acts on the bottom surface B4 of the tooth groove of the first clutch member 47, the first clutch member 47 is rotated in the direction indicated by the white arrow in FIG. 5. The rotation of the first clutch member 47 stops when one tooth side surface B1 of the first clutch tooth 47a abuts against the other tooth side surface A2 of the first fixed tooth 46a.

[0058] According to such a tapered surface structure, in conjunction with the switching of the clutch portion 45 to the high torque mode, the gap between one tooth side surface B1 of the first clutch tooth 47a and the other tooth side surface B2 of the first fixed tooth 46a can be automatically filled.

[0059] Further, when the speed reducer unit 30 operates in the high torque mode, the upper table 7 moves from the low speed switching position P2 to the lower end position P3. The workpiece is pressed between the upper mold P and the lower mold D. When the upper table 7 starts to move from the low speed switching position P2 and descends at a constant speed, a torque in the direction of pushing the upper table 7 downward acts on the drive motor 25.

[0060] When the torque in the direction of pushing the upper table 7 downward acts on the drive motor 25, as shown in FIG. 6(a), the first clutch member 47 pushes the fixed clutch member 46 in the direction toward the right side in the figure. At this time, one tooth side surface B1 of the first clutch tooth 47a presses the other tooth side surface A2 of the first fixed tooth 46a.

[0061] Therefore, without opening, the state where the one tooth side surface B1 of the first clutch tooth 47a and the other tooth side surface A2 of the first fixed tooth 46a are clogged is maintained. In the present embodiment, one tooth side surface B1 of the first clutch tooth 47a is formed higher than the other tooth side surface B2. Thereby, even in a situation where a high load accompanying the pressing of the workpiece is input, the tooth side surfaces B1 and A2 with a large height can receive the force. Thereby, the state where the first clutch tooth 47a and the first fixed tooth 46a are firmly engaged can be maintained.

[0062] By the way, when the upper table 7 approaches the lower end position P3, a deceleration torque acts, and the upper table 7 decelerates. At this time, only the frictional force between the elements of the mechanism that transmits power cannot support the weight of the upper table 7 which is a heavy object, and a force to receive the weight of the upper table 7 is generated in the drive motor 25. At this time, as shown in FIG. 6(b), the force acting on the first clutch member 47 is reversed, and the first clutch member 47 tries to move leftward by the amount of the gap. When the first clutch member 47 moves, the upper table 7 also moves downward. For this reason, even if the control device 100 stops the drive motor 25 in accordance with the lower end position P3, there arises a problem that the upper table 7 stops at a position deviated from the lower end position P3.

[0063] As shown in FIG. 7, according to the tapered surface structure of the present embodiment, when decelerating toward the lower end position P3, the force Fb required for decelerating the upper table 7 becomes the component force Fbh parallel to the tapered surface. For this reason, according to the tapered surface structure of the present embodiment, compared with the horizontal tooth shape, a large force is required to decelerate the upper table 7.

[0064] Further, as shown in FIG. 8, a pressing force Fc by a pressing member acts on the fixed clutch member 46. When decelerating toward the lower end position P3, in order for the gap between the one tooth side surface B1 of the first clutch tooth 47a and the other tooth side surface A2 of the first fixed tooth 46a to open, it is necessary to move the fixed clutch member 46 upward by a force exceeding the component force Fcv of the pressing force Fc.

[0065] Therefore, according to the tapered surface structure of the present embodiment, during the movement from the low-speed switching position P2 to the lower end position P3, as shown in FIG. 6(b), the movement of the first clutch member 47 in the left direction can be suppressed. For this reason, the upper table 7 can be accurately positioned with respect to the lower end position P3.

[0066] In the above-described embodiment, the drive unit including the drive motor 25 and the speed reducer unit 30 and the ball screw mechanism 55 are arranged in series in the vertical direction.

[0067] However, the drive unit and the ball screw mechanism 55 may be arranged in parallel such that the output shaft 41 of the speed reducer unit 30 and the ball screw nut 56 of the ball screw mechanism 55 are parallel. In this case, the output shaft 41 of the speed reducer unit 30 and the ball screw nut 56 of the ball screw mechanism 55 may be connected by a timing belt, and power may be transmitted through the timing belt.

[0068] As described above, the present embodiment has been described, but the discussions and drawings forming a part of this embodiment should not be understood as limiting this embodiment. Various alternative embodiments, examples, and operation techniques will become apparent to those skilled in the art from this embodiment.

Description of Reference Numerals

[0069] 1 Press brake 2 Side plate 5 Lower table 7 Upper table 20 Table drive device 25 Drive motor 26 Motor shaft 30 Speed reducer unit 31 Speed reducer 41 Output shaft 45 Clutch portion 46 Fixed clutch member 47 First clutch member 48 Second clutch member 55 Ball screw mechanism 56 Ball screw nut 57 Ball screw shaft 100 Control device

Claims

【Claim 1】 an upper table to which an upper die for bending a workpiece in cooperation with a lower die is attached; a speed reducer that reduces the rotation of a drive motor and outputs it at a reduction ratio of either a first reduction ratio or a second reduction ratio greater than the first reduction ratio; a conversion mechanism that moves the upper table in the vertical direction by converting the rotational motion, which is the output of the speed reducer, into a linear motion; a clutch portion that switches the reduction ratio of the speed reducer between the first reduction ratio and the second reduction ratio; and the clutch portion includes: an annular first clutch member provided with a plurality of first clutch teeth along the circumferential direction; an annular second clutch member provided with a plurality of second clutch teeth along the circumferential direction so as to face the plurality of first clutch teeth; an annular fixed clutch member provided movably in the axial direction between the first clutch member and the second clutch member, and having a plurality of first fixed teeth engageable with the plurality of first clutch teeth and a plurality of second fixed teeth engageable with the plurality of second clutch teeth provided along the circumferential direction; the fixed clutch member operates the speed reducer at the first reduction ratio by engaging with the second clutch member, and operates the speed reducer at the second reduction ratio by engaging with the first clutch member; the tip surface of each of the plurality of first fixed teeth is formed as a tapered surface inclined with respect to the circumferential direction; a tooth groove bottom surface against which the tip surface of the first fixed tooth abuts is provided between adjacent first clutch teeth, and the tooth groove bottom surface is formed as a tapered surface along the tip surface of the first fixed tooth; the height of one tooth side surface in the circumferential direction of the first clutch tooth is formed to be greater than the height of the other tooth side surface in the circumferential direction of the first clutch tooth; the one tooth side surface is located on the side that presses the first fixed tooth when pressing the workpiece between the upper die and the lower die; a press brake.

Images