Bending machine

Abstract

To detect crowning output with good accuracy.SOLUTION: A bending machine 1, which is equipped with a movable table 7 moving in a vertical direction Z and a stationery table 5 located at a position in the vertical direction Z corresponding to the movable table 7, comprises: an eccentric shaft 20 which bends the stationery table 5 in such a manner that an eccentric part 20C thereof is decentered from a rotary shaft Ar is vertically moved and presses the stationery table 5 when rotating around the rotary shaft Ar along a cross direction Y; a drive part 50 having an electric motor 51 for rotationally driving the eccentric shaft 20; a torque arm 61 which connects the drive part 50 to a processing machine body including the stationery table 5, and receives a reaction force CF when the drive part 50 has rotationally driven the eccentric shaft 20; and a strain detection sensor 63 which is attached to the torque arm 61, and can detect strain.SELECTED DRAWING: Figure 4C

Description

[Technical Field]

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

[0002] A technique for detecting the pressure force (crowning output) of a crowning mechanism provided in a bending machine has been known (Patent Document 1). The crowning mechanism disclosed in Patent Document 1 is a pair of crowning cylinders that are driven by hydraulic pressure or the like and are provided on the left and right near the center of the lower table. The crowning cylinders lift the lower table via a pressure block equipped with a piezoelectric sensor, thereby correcting the deflection of the lower table during bending. The crowning output is detected from the value of the piezoelectric sensor at this time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-094038 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the drive system for crowning mechanisms is becoming increasingly electric, shifting from cylinder drive using hydraulic oil such as hydraulic cylinders to motor drive, which uses the force generated by an electric motor to lift the table. Therefore, there is a demand for technology to detect crowning output compatible with motor-driven crowning mechanisms. [Means for solving the problem]

[0005] One aspect of the present invention is a bending machine comprising a movable table that moves in an up-down direction and a fixed table that is positioned at a corresponding position in the up-down direction relative to the movable table, and which comprises an eccentric shaft that, when rotated around a rotation axis along the front-to-rear direction, has an eccentric portion that is eccentric from the rotation axis that moves up and down and presses against the fixed table, thereby bending the fixed table; a drive unit having an electric motor that drives the eccentric shaft to rotate; a torque arm that connects the drive unit to the machine body including the fixed table and receives the reaction force when the drive unit drives the eccentric shaft to rotate; and a strain detection sensor attached to the torque arm that can detect strain.

[0006] In one aspect of the bending machine of the present invention, when the drive unit rotates the eccentric shaft, a reaction force from the eccentric shaft causes strain in the torque arm. A strain detection sensor attached to the torque arm detects the strain in the torque arm. This makes it possible to accurately detect the load when the eccentric shaft presses the fixed table, i.e., the crowning output, based on the strain in the torque arm. [Effects of the Invention]

[0007] According to one aspect of the present invention, the crowning output can be detected with high accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram schematically showing the configuration of a bending machine according to this embodiment. [Figure 2A] FIG. 2A is a top view showing the configuration of the fixed table. [Figure 2B] FIG. 2B is a front view showing the configuration of the fixed table. [Figure 2C] FIG. 2C is a side view showing the configuration of the fixed table. [Figure 3] FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2A, showing the configuration of the crowning mechanism and the load detection unit. [Figure 4A] FIG. 4A is a top view showing the configuration of the crowning mechanism and the load detection unit. [Figure 4B] FIG. 4B is a side view showing the configuration of the crowning mechanism and the load detection unit. [Figure 4C] FIG. 4C is a perspective view showing the configuration of the crowning mechanism and the load detection unit. [Figure 5] FIG. 5 is a diagram schematically showing the mounting position of the torque arm according to the first embodiment. [Figure 6] FIG. 6 is a diagram schematically showing the mounting position of the torque arm according to the second embodiment. [Figure 7] FIG. 7 is a diagram schematically showing the mounting position of the torque arm according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment) Hereinafter, a bending machine according to a first embodiment will be described with reference to the drawings.

[0010] FIG. 1 is a diagram schematically showing the configuration of a bending machine according to this embodiment. FIG. 2A is a top view showing the configuration of a fixed table. FIG. 2B is a front view showing the configuration of the fixed table. FIG. 2C is a side view showing the configuration of the fixed table. FIG. 3 is a cross-sectional view taken along line AA shown in FIG. 2A, showing the configuration of a crowning mechanism and a load detection unit. The configuration of the bending machine according to the first embodiment will be described below with reference to FIGS. 1 to 3.

[0011] In the following description, a left-right direction X, a front-rear direction Y, and an up-down direction Z are used to define the bending machine. The left-right direction X and the front-rear direction Y correspond to two directions that are orthogonal to the horizontal direction, and the up-down direction Z corresponds to the vertical direction. However, these directions are used merely for convenience in describing the bending machine in this embodiment.

[0012] The bending machine 1 of this embodiment is a bending machine comprising a movable table 7 that moves in the vertical direction Z and a fixed table 5 that is arranged at a position corresponding to the movable table 7 in the vertical direction Z. When the bending machine 1 rotates around a rotation axis Ar along the front-to-rear direction Y, an eccentric shaft 20 has an eccentric part 20C that is eccentric from the rotation axis Ar that moves up and down and presses against the fixed table 5, thereby bending the fixed table 5; a drive unit 50 having an electric motor 51 that drives the eccentric shaft 20 to rotate; a torque arm 61 that is connected to the machine body including the fixed table 5 and receives a reaction force CF when the drive unit 50 drives the eccentric shaft 20 to rotate; and a strain detection sensor 63 that is attached to the torque arm 61 and is capable of detecting strain.

[0013] The following describes the detailed configuration of the bending machine 1. The bending machine 1 is a processing machine that performs bending on a plate-shaped workpiece such as a metal plate. The bending machine 1 is, for example, a press brake, and performs bending on the workpiece by moving a movable table 7 in the vertical direction Z to pressurize the workpiece between an upper mold 8 such as a punch and a lower mold 6 such as a die.

[0014] The bending machine 1 includes a fixed table 5, a movable table 7, left and right hydraulic cylinders 9L, 9R, left and right crowning mechanisms 19L, 19R, left and right load detection units 60L, 60R, and a control device 80.

[0015] The bending machine 1 has left and right side frames 3L, 3R that face each other and are spaced apart in the left-right direction X. A fixed table 5 extends in the left-right direction X and is supported on the front lower parts of the side frames 3L, 3R. A movable table 7 extends in the left-right direction X and is supported on the front upper parts of the side frames 3L, 3R. The movable table 7 is configured to be movable in the up-down direction Z.

[0016] A lower die holder that detachably holds the lower die 6 is provided above the fixed table 5. The lower die holder has a holder groove formed in the left-right direction X into which the base of the lower die 6 is inserted. The lower die holder has a clamp mechanism that fixes the lower die 6 to the fixed table 5.

[0017] An upper die holder that detachably holds an upper die 8 is provided below the movable table 7. A holder groove for inserting the base of the upper die 8 is formed in the upper die holder along the left-right direction X. The upper die holder has a clamp mechanism that fixes the upper die 8 to the movable table 7.

[0018] The left and right hydraulic cylinders 9L, 9R are provided on the left and right upper parts of the side frames 3L, 3R, respectively. The left and right hydraulic cylinders 9L, 9R function as a lifting mechanism that moves the movable table 7 in the vertical direction Z. Note that in this embodiment, the left and right hydraulic cylinders 9L, 9R are used as an example of the lifting mechanism for the movable table 7, but the lifting mechanism for the movable table 7 is not limited to this. For example, the lifting mechanism may be configured to lift the movable table 7 in the vertical direction Z by being driven by a motor.

[0019] A front support plate 11 and a rear support plate 13 are provided on both sides of the fixed table 5 in the front-to-rear direction Y. The front support plate 11 and the rear support plate 13 are integrally attached to the fixed table 5 via left and right pivot shafts 15L, 15R that penetrate in the front-to-rear direction Y.

[0020] Left and right through-holes 17L, 17R are provided at symmetrical positions on the left and right with respect to the center position of the fixed table 5 in the left-right direction X, penetrating the front support plate 11 and the rear support plate 13 in the front-rear direction Y. The left and right through-holes 17L, 17R are each formed by a through-hole 17F provided in the front support plate 11 and a through-hole 17B provided in the rear support plate 13 (FIG. 3). Left and right crowning mechanisms 19L, 19R driven by an electric motor 51 are provided inside the left and right through-holes 17L, 17R. Details of the left and right crowning mechanisms 19L, 19R will be described later with reference to FIGS. 3 to 5.

[0021] Left and right load detection units 60L and 60R are attached to the left and right crowning mechanisms 19L and 19R. The left and right load detection units 60L and 60R individually detect the crowning outputs when the left and right crowning mechanisms 19L and 19R are driven. The crowning outputs of the left and right crowning mechanisms 19L and 19R are loads that the crowning mechanisms 19L and 19R press against the fixed table 5 and are proportional to the displacement of the fixed table 5. The left load detection unit 60L detects the crowning output of the left crowning mechanism 19L, and the right load detection unit 60R detects the crowning output of the right crowning mechanism 19R. The left and right load detection units 60L and 60R output the detected crowning outputs to the control device 80. The configuration of the left and right load detection units 60L and 60R will be described in detail below with reference to Figures 3 to 5.

[0022] The left and right through-holes 17L, 17R have the same shape, and the left and right crowning mechanisms 19L, 19R and the left and right load detecting units 60L, 60R have the same configuration. Therefore, hereinafter, when describing the left and right crowning mechanisms 19L, 19R and the left and right load detecting units 60L, 60R, they will simply be referred to as the through-hole 17, the crowning mechanism 19, and the load detecting unit 60.

[0023] The control device 80 is a computer such as a numerical control device (NC (Numerical Control) device). The computer is mainly composed of 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. A predetermined computer program is installed in the computer. The hardware processor executes the computer program, causing the computer to perform the functions of the control device 80.

[0024] The control device 80 controls the operation of the bending machine 1. Specifically, the control device 80 controls the left and right hydraulic cylinders 9L, 9R and the left and right crowning mechanisms 19L, 19R. By controlling the left and right hydraulic cylinders 9L, 9R and the left and right crowning mechanisms 19L, 19R, the control device 80 can control the movement of the movable table 7 in the up-down direction Z and the curved state of the fixed table 5.

[0025] The control device 80 controls the bending state of the fixed table 5 based on workpiece information such as the workpiece thickness, bending length, and material, product information such as the bending angle and flange dimensions, die information such as the types, dimensions, and angles of the lower die 6 and upper die 8, and processing information such as the positions of the lower die 6 and upper die 8. Specifically, the control device 80 calculates the amount of deflection of the fixed table 5 and movable table 7 in the left-right direction X during bending based on the workpiece information, product information, die information, processing information, etc. The control device 80 drives the left and right crowning mechanisms 19L, 19R to bend the fixed table 5 so as to cancel out the amount of deflection of the fixed table 5 and movable table 7 in the left-right direction X and maintain a constant distance between the lower die 6 and upper die 8.

[0026] More specifically, the control device 80 calculates the amount of curvature of the fixed table 5 to cancel out the amount of bending of the fixed table 5 and the movable table 7 in the left-right direction X, and calculates the target outputs of the left and right crowning mechanisms 19L and 19R (hereinafter referred to as "left and right crowning outputs") required to achieve the calculated amount of bending. The control device 80 controls the left and right crowning outputs detected by the left and right load detection units 60L and 60R so that they become the target outputs. Therefore, the control device 80 feedback-controls the left and right crowning outputs. This allows the control device 80 to accurately control the amount of bending of the fixed table 5, cancel out the amount of bending of the fixed table 5 and the movable table 7 in the left-right direction X, and bend the fixed table 5 so that the gap between the lower mold 6 and the upper mold 8 is constant. Note that the control device 80 does not need to calculate the target outputs of the left and right crowning mechanisms 19L and 19R each time; if they are given as processing conditions, they can be used.

[0027] As explained above, in order to cancel out the amount of deflection of the fixed table 5 and the movable table 7 during bending and to bend the fixed table 5 so that the distance between the lower die 6 and the upper die 8 is constant, it is necessary to appropriately control the left and right crowning outputs. Therefore, accurately detecting the left and right crowning outputs is an important element in bending.

[0028] In the bending machine 1 configured as described above, a plate-shaped workpiece is positioned on the lower die 6 attached to the fixed table 5. The control device 80 lowers the movable table 7 toward the fixed table 5. As a result, the workpiece is pressed between the upper die 8 and the lower die 6, and the upper die 8 and the lower die 6 cooperate to bend the workpiece to the desired target bending angle.

[0029] The detailed configurations of the crowning mechanism 19 and the load detection unit 60 will be described below with reference to Fig. 3 to Fig. 5. Fig. 4A is a top view showing the configurations of the crowning mechanism and the load detection unit. Fig. 4B is a side view showing the configurations of the crowning mechanism and the load detection unit. Fig. 4C is a perspective view showing the configurations of the crowning mechanism and the load detection unit. Fig. 5 is a diagram schematically showing the mounting position of the torque arm according to the first embodiment.

[0030] First, a detailed description will be given of the configuration of the crowning mechanism 19. The crowning mechanism 19 includes an eccentric shaft 20 and a drive unit 50.

[0031] 3, the eccentric shaft 20 is made up of three parts: a front part 20F, a central part (eccentric part) 20C, and a rear part 20B, and rotates around a rotation axis Ar along the front-to-rear direction Y. The centers of the front part 20F and the rear part 20B coincide with the rotation axis Ar of the eccentric shaft 20, and the center of the eccentric part 20C is eccentric from the rotation axis Ar of the eccentric shaft 20 by a predetermined eccentricity ΔE.

[0032] The eccentric shaft 20 is inserted into the through-hole portion 17. Specifically, the front portion 20F is inserted into the through-hole 17F provided in the front support plate 11, and the rear portion 20B is inserted into the through-hole 17B provided in the rear support plate 13. The eccentric shaft 20 is supported by the front support plate 11 and the rear support plate 13 via a support ring 30 and is rotatable. Specifically, the front portion 20F is supported by the front support plate 11 via the support ring 30, and the rear portion 20B is supported by the rear support plate 13 via the support ring 30. When the eccentric shaft 20 is supported by the front and rear support plates 11 and 13, the eccentric portion 20C is configured to be located below the pressure-receiving surface 5P of the fixed table 5. The pressure-receiving surface 5P of the fixed table 5 is provided at the lower end of the fixed table 5.

[0033] The eccentric portion 20C of the eccentric shaft 20 is surrounded by a center ring 70 having a through-hole at its center. A pair of bearings 42 aligned in the front-to-rear direction are fitted into the center ring 70, and the eccentric portion 20C is rotatably supported by the pair of bearings 42. When the eccentric shaft 20 rotates around the rotation axis Ar in the rotation direction R, the eccentric portion 20C, which is eccentric from the rotation axis Ar by a predetermined eccentricity amount ΔE, moves up and down. As the center ring 70 moves up and down in conjunction with the movement of the eccentric portion 20C, the center ring 70 presses the pressure-receiving surface 5P of the fixed table 5 upward against the front and rear support plates 11 and 13. By pressing the pressure-receiving surface 5P of the fixed table 5, the eccentric shaft 20 bends the fixed table 5 convexly upward. Therefore, when the rotation angle of the eccentric shaft 20 changes, the load when the center ring 70 presses the pressure-receiving surface 5P of the fixed table 5, that is, the crowning output, changes.

[0034] The support rings 30 are cylindrical rings provided on the front and rear support plates 11, 13, respectively, and rotatably support the eccentric shaft 20. The support rings 30 have an outer circumferential portion 31 supported by through holes 17F, 17B provided in the front and rear support plates 11, 13, and an inner circumferential portion 32 that supports the eccentric shaft 20 rotatably around the rotation axis Ar. A bearing portion 40 that supports the eccentric shaft 20 is fitted into the inner circumferential portion 32. The bearing portion 40 is, for example, a self-aligning roller bearing.

[0035] In the present embodiment, the eccentric shaft 20 is supported by the front and rear support plates 11, 13 via the support ring 30, but the configuration for supporting the eccentric shaft 20 is not limited to this. For example, the eccentric shaft 20 may be supported by the front and rear support plates 11, 13 without the support ring 30 by fitting bearings 40 into the front and rear through holes 17F, 17B, respectively.

[0036] The drive unit 50 has an electric motor 51 and a reducer 52. In this embodiment, the electric motor 51 and the reducer 52 are connected via a motor base 54. Therefore, the electric motor 51 and the reducer 52 are integrated.

[0037] The electric motor 51 is, for example, a servo motor. The electric motor 51 rotates the output shaft 55 to rotate the eccentric shaft 20. The rotation angle of the rotationally driven eccentric shaft 20 is proportional to the crowning output, and the crowning output changes depending on the rotation angle of the eccentric shaft 20. The electric motor 51 is controlled by a control device 80.

[0038] The reducer 52 reduces the rotational speed of the electric motor 51 and transmits it to the eccentric shaft 20. The reducer 52 is a concentric-shaft reducer using planetary gears. The rotational speed of the electric motor 51 reduced by the reducer 52 is transmitted to the eccentric shaft 20 via the connecting portion 53. In other words, the reducer 52 amplifies the rotational torque of the electric motor 51 and transmits it to the eccentric shaft 20. The reduction ratio of the reducer 52 is set appropriately based on the rigidity of the fixed table 5. Note that, although the present embodiment has exemplified a concentric-shaft reducer using planetary gears as the reducer 52, the type of the reducer 52 is not limited thereto. For example, the reducer 52 may be a parallel-shaft gear reducer or a vertical-shaft gear reducer.

[0039] The configuration of the crowning mechanism 19 has been described above. The left and right crowning mechanisms 19L, 19R can be controlled independently. By controlling the left and right crowning mechanisms 19L, 19R independently, the curvature state of the fixed table 5 in the left-right direction X can be adjusted. Adjusting the curvature state includes adjusting the position at which the fixed table 5 is curved (such as the left side, center, or right side), the shape of the curvature, the degree of curvature, etc.

[0040] Next, a detailed description will be given of the configuration of the load detection unit 60. The load detection unit 60 has a torque arm 61 and a strain detection sensor 63.

[0041] The torque arm 61 receives a reaction force (torque) CF when the drive unit 50 is connected to the rear support plate 13 and the drive unit 50 drives and rotates the eccentric shaft 20. Specifically, one end of the torque arm 61 is fixed to the motor base 54, and the other end of the torque arm 61 is fixed to the rear support plate 13. The torque arm 61 is fastened to the motor base 54 and the rear support plate 13 with bolts and nuts, respectively. This allows the rotational torque of the electric motor 51 to be transmitted to the eccentric shaft 20, and the electric motor 51 can drive and rotate the eccentric shaft 20.

[0042] In the present embodiment, the torque arm 61 is fixed to the motor base 54 and the rear support plate 13, respectively, thereby connecting the drive unit 50 to the rear support plate 13; however, the method of connecting the drive unit 50 is not limited to this. The torque arm 61 may be structured to be fixed to a portion of the drive unit 50 that receives the reaction force CF when the eccentric shaft 20 is driven to rotate. Therefore, when the electric motor 51 and the reducer 52 are integrated by the motor base 54, one end of the torque arm 61 may be fixed not only to the motor base 54 but also to the electric motor 51 itself or to the reducer 52. Furthermore, the other end of the torque arm 61 may be fixed not only to the rear support plate 13 but also to the front support plate 11, left and right side frames 3L, 3R, or the like that constitute the processing machine main body.

[0043] The strain detection sensor 63 is a sensor capable of detecting strain. For example, a strain gauge, a distance sensor, an angle sensor, or the like can be used as the strain detection sensor 63. In this embodiment, a strain gauge is used as the strain detection sensor 63. The strain detection sensor 63 is attached to the torque arm 61. Specifically, the strain detection sensor 63 is attached to the torque arm 61 via a mounting plate 62. The mounting plate 62 is formed of a material whose mechanical properties, such as thickness and material, differ from those of the torque arm 61, and is detachably attached to the torque arm 61. When the electric motor 51 rotates the eccentric shaft 20 and displaces the fixed table 5, a reaction force (torque) CF from the eccentric shaft 20 acts on the torque arm 61. Strain corresponding to the reaction force CF is generated in the torque arm 61 that receives the reaction force CF, and in the mounting plate 62 attached to the torque arm 61. The strain detection sensor 63 detects the reaction force CF by detecting the strain generated in the mounting plate 62. The strain generated in the mounting plate 62 is proportional to the strain generated in the torque arm 61 and is proportional to the reaction force CF from the eccentric shaft 20. Furthermore, the reaction force CF from the eccentric shaft 20 is proportional to the rotation angle of the eccentric shaft 20, i.e., the crowning output (displacement of the fixed table 5). Therefore, the strain detection sensor 63 detects the reaction force CF received by the torque arm 61 when the eccentric shaft 20 is rotationally driven, and therefore the crowning output. The strain detection sensor 63 transmits the detected reaction force CF to the control device 80 as a crowning output.

[0044] The control device 80 controls the drive unit 50 based on the reaction force CF received by the torque arm 61. Specifically, the control device 80 drives and rotates the eccentric shaft 20 so that the crowning output measured by the strain detection sensor 63 becomes the target output.

[0045] [Action and effect] As described above, according to the first embodiment, the following effects can be obtained.

[0046] The bending machine 1 includes a drive unit 50 having an electric motor 51 that rotates the eccentric shaft 20, a torque arm 61 that receives a reaction force CF when the drive unit 50 rotates the eccentric shaft 20 by connecting the drive unit 50 to a machine body including a fixed table 5, and a strain detection sensor 63 that is attached to the torque arm 61 and can detect strain. When the drive unit 50 rotates the eccentric shaft 20, strain is generated in the torque arm 61 that receives the reaction force CF from the eccentric shaft 20. The strain detection sensor 63 attached to the torque arm 61 detects the strain generated in the torque arm 61. As a result, the load when the eccentric shaft 20 presses the fixed table 5, i.e., the crowning output, can be detected with high accuracy based on the strain generated in the torque arm 61.

[0047] The crowning output is proportional to the reaction force CF received by the torque arm 61. The torque arm 61 is provided individually for each of the left and right crowning mechanisms 19L, 19R, and each is composed of an independent structure. This allows the crowning output of one of the left and right crowning mechanisms 19L, 19R to be detected without being affected by the crowning output of the other. Therefore, the left and right crowning outputs can be detected with high accuracy. Furthermore, since the left and right crowning outputs can be detected with high accuracy, the gap between the punch and die during bending can be kept constant, improving passing accuracy.

[0048] The strain detection sensor 63 is attached to the torque arm 61 via a mounting plate 62. The mounting plate 62 has different mechanical properties, such as thickness and material, from the mounting plate 62, resulting in different strain characteristics between the mounting plate 62 and the torque arm 61. This allows the strain characteristics of the mounting plate 62 to be adjusted to match the characteristics of the strain detection sensor 63, making it possible to accommodate strain detection sensors 63 with different characteristics. For example, the bending machine 1 uses a strain detection sensor that detects the opening amount of the C-shaped side frames 3L and 3R. However, the strain detection sensor that detects the opening amount (strain amount) of the side frames 3L and 3R has a different resolution from the strain detection sensor 63 that detects the strain of the torque arm 61. However, by adjusting the strain characteristics using the mounting plate 62, sensors with different detection resolutions can be used as the strain detection sensor 63. This allows the components used in the bending machine 1 to be shared, thereby reducing manufacturing costs.

[0049] The mounting plate 62 is detachably attached to the torque arm 61. This allows a desired mounting plate 62 to be attached to the torque arm 61 from among a plurality of mounting plates 62 with different mechanical properties such as plate thickness and material. Therefore, when manufacturing the bending machine 1 or at the work site where the bending machine 1 is actually operated, a mounting plate 62 can be selected according to the specifications and processing form of the bending machine 1.

[0050] The drive unit 50 includes a reducer 52 that reduces the rotation of the electric motor 51 and transmits the reduced rotation to the eccentric shaft 20. When the electric motor 51 and the reducer 52 are integrated, the torque arm 61 is fixed to the electric motor 51 or the reducer 52. When the electric motor 51 and the reducer 52 are integrated, the electric motor 51 and the reducer 52 are components that receive a reaction force CF when the eccentric shaft 20 is driven to rotate. Therefore, by being fixed to the electric motor 51 or the reducer 52, the torque arm 61 can receive the reaction force CF from the eccentric shaft 20. As a result, the strain detection sensor 63 attached to the torque arm 61 via the mounting plate 62 can measure the reaction force CF received by the torque arm 61. Therefore, the control device 80 can accurately control the crowning output based on the reaction force CF received by the torque arm 61.

[0051] The control device 80 controls the drive unit 50 based on the reaction force CF received by the torque arm 61, which is detected by the strain detection sensor 63. The strain generated in the torque arm 61 is caused by the reaction force CF that is generated when the eccentric shaft 20 is driven to rotate. Therefore, the control device 80 controls the drive unit 50 based on the strain generated in the torque arm 61, thereby enabling accurate control of the crowning output.

[0052] (Second embodiment) Fig. 6 is a diagram schematically showing the mounting position of a torque arm according to the second embodiment. Hereinafter, the bending machine 1 according to the second embodiment will be described with reference to Fig. 6. Only the differences from the first embodiment will be described, and the description of the other same configurations will be omitted. Note that the second embodiment can also achieve the same effects as the first embodiment.

[0053] In the bending machine 1 according to the second embodiment, the electric motor 51 and the reducer 52 are separate bodies. Specifically, the electric motor 51 is fixed to a member 16 that is different from the rear support plate 13. In this case, the torque arm 61 is fixed to the reducer 52. The reducer 52 is a part that receives a reaction force CF when the eccentric shaft 20 is driven to rotate. By fixing the torque arm 61 to the reducer 52, the control device 80 can detect the crowning output from the reaction force CF received by the torque arm 61.

[0054] (Third embodiment) Fig. 7 is a diagram schematically showing the mounting position of a torque arm according to the third embodiment. Hereinafter, the bending machine 1 according to the third embodiment will be described with reference to Fig. 7. Only the differences from the first embodiment will be described, and the description of the other same configurations will be omitted. Note that the third embodiment can also achieve the same effects as the first embodiment.

[0055] In the bending machine 1 according to the third embodiment, the drive unit 50 does not include a reducer 52, and the electric motor 51 directly drives and rotates the eccentric shaft 20. In this case, the torque arm 61 is fixed to the electric motor 51. The electric motor 51 is a part that receives a reaction force CF when the eccentric shaft 20 is driven and rotated. By fixing the torque arm 61 to the electric motor 51, the control device 80 can detect the crowning output from the reaction force CF received by the torque arm 61.

[0056] Although the embodiments of the present invention have been described above, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. Various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art from this disclosure. [Explanation of symbols]

[0057] 1. Bending machine 5 Fixed table 5P pressure receiving surface 7 Movable table 11 Front support plate 13 Rear support plate 20 Eccentric shaft 20C Center part (eccentric part) 50 Drive unit 51 Electric motor 52 Reducer 60 Load detection unit 61 Torque arm 62 Mounting plate 63 Strain detection sensor 80 Control device Ar rotation axis CF reaction force ΔE Predetermined eccentricity

Claims

1. A bending machine including a movable table that moves in a vertical direction and a fixed table that is disposed at a position corresponding to the movable table in the vertical direction, an eccentric shaft that, when rotated around a rotation axis along a front-rear direction, has an eccentric portion that is eccentric from the rotation axis and moves up and down to press the fixed table, thereby bending the fixed table; a drive unit having an electric motor that rotates and drives the eccentric shaft; a torque arm that connects the drive unit to a processing machine body including the fixed table and receives a reaction force when the drive unit rotationally drives the eccentric shaft; a strain detection sensor attached to the torque arm and capable of detecting strain; Bending machine.

2. The strain detection sensor is attached to the torque arm via a mounting plate. The bending machine according to claim 1.

3. the drive unit includes a reducer that reduces the rotation speed of the electric motor and transmits the reduced speed to the eccentric shaft, When the electric motor and the reducer are integrated, the torque arm is fixed to the electric motor or the reducer. The bending machine according to claim 1.

4. the drive unit includes a reducer that reduces the rotation speed of the electric motor and transmits the reduced speed to the eccentric shaft, When the electric motor and the reducer are separate, the torque arm is fixed to the reducer. The bending machine according to claim 1.

5. The strain sensor further includes a control device that controls the drive unit based on the strain detected by the strain detection sensor. The bending machine according to any one of claims 1 to 4.

6. The mounting plate is made of a material having mechanical properties different from those of the torque arm. The bending machine according to claim 2.

7. The mounting plate is detachably attached to the torque arm. The bending machine according to claim 2 or 6.

8. the processing machine body further includes front and rear support plates disposed on both sides of the fixed table in the front-rear direction and rotatably supporting both ends of the eccentric shaft, the drive unit is provided on one of the front and rear support plates, The torque arm is fixed to the one support plate. The bending machine according to claim 1.

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