JPH07275946A - Bending machine - Google Patents

Abstract

PURPOSE:To minimize variance of bending angles by detecting the thickness of a work in the case of needing a large pressurizing force in working. CONSTITUTION:In a bending machine in which a fixed table 3 and a ram 7 that is freely movable back and forth are provided oppositely facing each other on a frame 1, and in which bending is performed on a work with a cooperation between one mold 5 provided on the fixed table 3 and the other mold 9 provided on the ram 7; the machine is provided with a screw pressurizing device 17 and a hydraulic device 11 for imparting a pressurizing force at the time of a reciprocating movement and bending work of the ram 7, a ram position detector 39 for detecting the position of the ram 7, and a revolution detector 35 for a driving motor 21 for driving the screw pressurizing device 17. In addition, a control device 67 with a function for detecting thickness is provided, by which the thickness of a work is detected, as such, at the time of generation of a difference between a first detection value detected by the ram position detector 39, when one mold 5 or the other mold 9 is brought into contact with the work, and a second detection value detected by the revolution detector 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate for detecting a plate thickness of a work when a ram is reciprocally moved so that one mold and the other mold cooperate to bend a work. The present invention relates to a bending machine having a thickness detection function.

[0002]

2. Description of the Related Art Conventionally, in a bending machine, when a work is bent by cooperation of an upper die and a lower die, one of the upper die and the lower die is fixed on a fixed table. In general, the ram is reciprocally movable and the other is reciprocally movable.

As a drive device for the ram, for example, as known from Japanese Patent Laid-Open No. 63-13621,
Well-known means are hydraulic cylinders provided on both the left and right sides, and a means for rotating a ball screw with a servomotor, as known from Japanese Patent Laid-Open No. 4-75798.

[0004]

By the way, of the above-mentioned conventional techniques, in the former means for driving the ram by the hydraulic cylinder, the hydraulic cylinder is controlled by the servo valve and the position of the ram is detected by the linear sul. Therefore, the pressing force is large, but the positioning accuracy is 2/100 to 3/10.
Inferior to 0 mm, 1/100 to 2/10 due to this resolution
The plate thickness detection in units of 0 mm is the limit.

On the other hand, in the latter means for rotating the ball screw by the servo motor to drive the ram, it is possible to perform highly accurate positioning with a positioning accuracy of 2/1000 to 3/1000 mm, but the pressing force is so large. However, there was a problem that only 50 tons could be produced at most.

An object of the present invention is to provide a bending machine capable of reducing the variation in bending angle by detecting the plate thickness of a work when a large pressing force is required during processing. .

[0007]

In order to achieve the above object, a bending machine of the present invention is provided with a fixed table and a ram capable of reciprocating, which are opposed to a frame, and which is provided on the fixed table. In a bending machine that bends a work in cooperation with the other die provided in the ram and the other die provided in the ram, reciprocating movement of the ram and screw application for applying a pressing force during the bending work. A pressure device and a hydraulic device, a ram position detection means for detecting the position of the ram, a rotation detection means of a drive motor for driving the screw pressure device, and the one die or the other die should be machined. A plate thickness that is detected as a plate thickness of the work when a difference occurs between the first detection value detected by the ram position detection means and the second detection value detected by the rotation detection means when abutting on the work. With a control device having a detection function It is to characterized in that it comprises a.

In the bending machine, the screw pressure device, the drive motor, and the rotation detecting means are provided on both sides of the ram in the frame, and the ram position detecting means is provided on the left and right sides of the fixed table and the ram. It is desirable to be provided on both sides.

[0009]

[Operation] By using the bending machine as described above,
After the ram is moved forward by the screw pressure device and one mold or the other mold comes into contact with the work to be processed, the screw pressure device and hydraulic device apply pressure to the work and bend it. Is done. At this time, the amount of movement of the ram during forward movement is detected by the ram position detecting means and the rotation detecting means of the drive motor. Then, a difference occurs between the first detection value detected by the ram position detection means and the second detection value detected by the rotation detection means when one die or the other die comes into contact with the work, The plate thickness detection function of the control device detects the plate thickness detection position of the work. The plate thickness of the work is detected based on the plate thickness detection position.

Bending with a small variation in bending angle is performed by changing the amount of protrusion of the mold to an appropriate value based on the detected plate thickness detection position of the work.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings.

Referring to FIG. 1, for example, a press brake as a bending machine is equipped with side frames 1 as frames which are erected on both left and right sides, and a fixed table 3 is provided under each side frame 1. Is fixedly provided. A lower mold 5 for bending is detachably attached to the fixed table 3.

A ram 7 which is reciprocally movable (moves up and down) facing the fixed table 3 is provided above the side frame 1.
And an upper die 9 for bending is detachably attached to the lower portion of the ram 7.

A hydraulic cylinder 11 as a hydraulic device is attached to the upper portion of each side frame 1, and a ram is attached to the tip (lower end) of a piston rod 13 inserted into each hydraulic cylinder 11 with a mounting block 15. It is attached to the upper left and right of 7.

Each of the hydraulic cylinders 11 is provided with a screw pressure device 17. More specifically, each screw pressure device 1
A support block 19 which is a member of No. 7 is integrated inside the hydraulic cylinder 11. Each support block 1
Servo motors 21 are mounted inside 9 and a drive gear 25 is fitted to the output shaft 23 of each servo motor 21. Each drive gear 25 has a separate gear 27
Are meshed.

An upper part of a ball screw 29 extending in the vertical direction is inserted and fixed to each gear 27. Moreover, each ball screw 29 is rotatably mounted on the support block 19, a nut member 31 is screwed onto the ball screw 29, and each nut member 31 is fixed to the upper portion of the ram 7. It is provided. Each nut member 3
1 is provided with, for example, a load cell 33 as a pressing force detecting means for detecting the pressing force of the ball screw 29. Below the servo motor 21, a pulse generator 35 is provided as a rotation detecting means for detecting the rotation of the output shaft 23.

A support bar 37 extending in the Z-axis direction (vertical direction) is erected on the fixed table 3 outside the side frame 1, and a ram position detecting means 39 is provided above the support bar 37. Partial linear scale 4
1, and pointers 43 are provided on both left and right sides of the ram 7.

When each servo motor 21 is driven by the above structure, the output shaft 23, the drive gear 25, and the driven gear 2 are driven.
The ball screw 29 is rotated via 7. By the rotation of each ball screw 29, the ram 7 is reciprocated (moved up and down) in the Z-axis direction via the nut member 31.

Moreover, the rotation of the output shaft 23 can be detected by each pulse generator 35, and the position of the ram 7 can be detected by the linear scale 41 and the pointer 43. Further, the load cell 33 can detect the pressing force of the ball screw 29.

By operating each of the hydraulic cylinders 11 and lowering the piston rod 13, pressure is applied to the ram 7, and the lower die 5 and the upper die 9 for bending work are applied.
The work will be bent in cooperation with.

FIG. 2 shows a hydraulic circuit for reciprocating and positioning the ram 7. One end of a pipe 45 is connected to the lower oil chamber 11D of the hydraulic cylinder 11, and an accumulator 47 is connected to the other end of the pipe 45. Further, one end of a pipe 49 is connected to the upper oil chamber 11U of the hydraulic cylinder 11, and a tank T is connected to the other end of the pipe 49. Moreover, a check valve 51 is provided in the middle of the pipe 49.

One end of the pipe 53 is connected to the middle of the pipe 49, and a relief valve 55 is connected to the other end of the pipe 53. A pipe 57 is connected to one end of the relief valve 55, and the tank T is connected to the other end of the pipe 57. A pump P is provided in the middle of the pipe 57, and a drive motor M is connected to the pump P.

One end of the pipe 59 is connected in the middle of the pipe 57, and the other end of the pipe 59 is connected to the P port of the 4-port / 2-position switching valve 61. One end of a pipe 63 is connected to the A port of the switching valve 61, and the other end of the pipe 63 is connected to the check valve 51. The B port of the switching valve 61 is blind.

The servo motor 21 includes a servo amplifier 65.
Is connected to the controller 67 which is a control device. In addition, the load cell 33 and the pulse generator 3
5 and the linear scale 41 are also connected to the controller 67. Further, a pressure control valve 71 as a hydraulic pressure adjusting device is connected to the controller 67 via a pressure control valve amplifier 69.

With the above construction, when the drive motor M is driven to operate the pump P, hydraulic pressure is discharged from the tank T, and the upper oil chamber 11U of the hydraulic cylinder 11 is passed through the pipe 57, the relief valve 55, the pipe 53 and the pipe 49. Is supplied to. Then, the piston rod 13 descends. The pressure of the ram 7 is controlled by the pressure control valve 71 according to a command from the controller 67. At that time, the hydraulic pressure in the lower oil chamber 11D of the hydraulic cylinder 11 is temporarily stored in the accumulator 47.

When the ball screw 29 is rotated by driving the servo motor 21, the ram 7 descends. At that time, since the upper oil chamber 11U of the hydraulic cylinder 11 has a negative pressure, the upper oil chamber 11 passes from the tank T through the check valve 51 and the pipe 49.
The hydraulic pressure will be sucked into U.

Further, by supplying hydraulic pressure from the accumulator 47 to the lower oil chamber 11D of the hydraulic cylinder 11, the piston rod 13 rises and the ram 7 also rises.

At this time, the hydraulic pressure in the pipe 57 is
9, check valve 5 via switching valve 61 and piping 63
By depressing 1, the hydraulic pressure in the upper oil chamber 11U of the hydraulic cylinder 11 is returned to the pump P via the pipe 49 and the check valve 51.

The hydraulic circuit in FIG. 2 changes the swash plate angle of the pump P and controls the pressure in response to the load.

FIG. 3 shows a hydraulic circuit of another embodiment which is an alternative to that shown in FIG. In FIG. 3, the same parts as those in FIG. 2 are designated by the same reference numerals, and overlapping description will be omitted. That is, the hydraulic circuit of FIG. 3 is a type that performs only pressure control using the constant discharge pump P, and only the pump model is different, so detailed description will be omitted.

FIG. 4 shows a control block diagram for controlling the ram 7 to reciprocate. It is composed of various parts described above in FIG. 4, and the pressing force detected by the load cell 33 is fed back to the controller 67, and the rotation of the output shaft 23 detected by the pulse generator 35 is fed back before the servo amplifier 65. The position of the ram 7 detected by the linear scale 41 is fed back to the front of the controller 67.

Therefore, based on the feedback signals detected by the load cell 33, the pulse generator 35, and the linear scale 41, the controller 67 instructs the rotation of the servo motor 21 to be controlled and the pressure control valve 7 to be operated.
1 will be controlled.

In FIG. 4, only the control block diagram for controlling the right ram 7 is shown, but the control block diagram for controlling the left ram 7 is not shown but has the same structure. .

Next, the operation of bending the work by cooperation of the lower die 5 and the upper die 9 by the operation of the ram 7 will be described. As shown in FIG. Upper limit position Z
After the servomotor 21 is driven for the time T ₁ from the position Z ₀ to the position Z ₀ , the ram 7 is started to descend from the position Z ₀ . At that time, the hydraulic cylinder 11 does not work from the position Z to the position Z ₀ . The ram 7 is made to approach rapidly for the time T ₂ from the position Z ₀ to the position Z ₁ . At this time, hydraulic cylinder 1
The hydraulic pressure is sucked from the tank T into the upper oil chamber 11U of No. 1 through the pipe 49 and the check valve 51, and is in the suction state.

Time T from position Z ₁ to position Z ₂
Only ₃ makes ram 7 approach very slowly. In this state, the hydraulic cylinder 11 is in the suction state as described above. When the lower end of the ram 7 reaches the position Z ₂ , the upper die 9 comes into contact with the work on the lower die 5, and the bending process is started. At time T ₄ the ram 7 has reached the position Z ₂ to the position Z _3, keeping the pressure of the ball screw 29 for example 0-10 tons pressing force to borrow the power of the hydraulic cylinder 11 when the shortage . That is, from the position Z ₂ to the hydraulic cylinder 1
Activate 1. The upper oil chamber 11 of this hydraulic cylinder 11
The hydraulic pressure supplied to U is controlled by the pressure control valve 71.

At a time T ₅ from the position Z ₃ to the position Z ₄ , the bending work is performed without being pushed. At that time, the ball screw 29 is in an operating state and the hydraulic cylinder 11
Is under pressure. Position Z ₄ to bending is completed at the time, the ram 7 is returned to the upper limit position Z soaring at time T ₆ from the position Z ₄ to the position Z _0. At this time, the hydraulic cylinder 1
1 serves as a help to help Ram 7 ascend.

In the above-mentioned operation, the respective positions Z _{0 to} Z ₄ of the ram 7 are constantly detected by the linear scale 41, and the rapid approach, slow speed and rapid movement of the ram 7 are controlled by the pulse generator 35 of the servo motor 21. The rotation of the output shaft 23 is detected and controlled.

As described above, when the ram 7 is reciprocally moved and the lower die 5 and the upper die 9 cooperate with each other to bend a work, the positioning of the ram 7 during the reciprocating movement is mainly performed by screwing. Pressure device 1
7. The hydraulic cylinder 11 mainly applies pressure during bending.
By doing so, the positioning accuracy is high and the bending process can be performed with a large pressing force.

When the lower end of the ram 7 reaches the position Z ₂ , the upper die 9 comes into contact with the work on the lower die 5 and the bending process is started. Is detected by the linear scale 41 and the pulse generator 35 of the servomotor 21. Then, the difference between the first detection value detected by the linear scale 41 and the second detection value detected by the pulse generator 35 causes the plate thickness detection position of the workpiece to be processed to be detected by the control device. That is, the distance until the upper die 9 comes into contact with the lower die 5 is stored in the control device in advance, so that the plate thickness of the workpiece can be detected based on this distance and the plate thickness detection position.

Therefore, when the work is bent, trial bending is performed on the work to confirm that the target bending angle is achieved, and the plate thickness detection position at that time is stored in the control device. Then, for the second and subsequent sheets, the bending amount is reduced by changing the plunge amount of the upper mold 9 based on the plate thickness detection position during the trial bending, thereby reducing the variation in the bending angle and bending with good bending accuracy. It can be performed.
Thus, a uniform bending angle can be achieved even if the plate thickness of the work changes.

The present invention is not limited to the above-described embodiments, but can be implemented in other modes by making appropriate changes. In this embodiment, the lower die 5 is provided on the fixed table 3 and the upper die 9 is provided at the lower portion of the ram 7. However, the lower die 5 is provided on the reciprocating ram 7 and the upper die 9 is reciprocally moved. A folding machine of the type in which the die 9 is provided below the fixed table 3 may be used.

Although the ram drive control of the present embodiment has been described as an example in which the linear scale 41 as shown in FIG. 4 is used to perform full-closed control, it is also possible to perform semi-closed control without the linear scale 41. Is.

In the bending machine shown in FIG. 1, the screw pressurizing device 17 is provided inside the hydraulic cylinders 11 provided on the left and right sides. It may be provided on the side, or may be provided on the front and rear sides of each hydraulic cylinder 11. Further, although the example in which the hydraulic cylinders 11 are provided on both the left and right sides has been described, the hydraulic cylinders 11 may be provided at substantially the central portion.

[0044]

As can be understood from the above description of the embodiments, according to the present invention, the ram is reciprocally moved and the work is bent by the cooperation of the one die and the other die. When the ram is moved, the positioning of the ram during reciprocating motion is performed mainly by the screw pressure device, and the pressure during bending is mainly performed by the hydraulic device, so that the positioning accuracy is high and large. Bending can be performed by pressure.

When one die or the other die comes into contact with the work and bending is started, the amount of movement of the ram is detected by the ram position detecting means and the rotation detecting means of the drive motor. Therefore, by detecting the difference between the first detection value detected by the ram position detection means and the second detection value detected by the rotation detection means, it is possible to detect the plate thickness detection position of the workpiece to be machined. It is possible to detect the plate thickness at the same time. The thrust of the mold can be changed based on this plate thickness detection position, and bending work can be performed to obtain a uniform bending angle with a small variation in the bending angle even if the plate thickness of the workpiece changes. .

[Brief description of drawings]

FIG. 1 is a front view of a bending machine according to an embodiment of the present invention.

2 is a hydraulic circuit diagram of an embodiment for reciprocating the ram in FIG. 1. FIG.

FIG. 3 is a hydraulic circuit diagram of another embodiment replacing FIG.

FIG. 4 is a control block diagram for reciprocating a ram.

FIG. 5 is an explanatory diagram of an operation of bending a work by reciprocating a ram.

[Explanation of symbols]

 1 Side Frame (Frame) 3 Fixed Table 5 Lower Die 7 Ram 9 Upper Die 11 Hydraulic Cylinder (Hydraulic Device) 17 Screw Pressing Device 21 Servo Motor 23 Output Shaft 29 Ball Screw 33 Load Cell 35 Pulse Generator 39 Ram Position Detecting Means 41 linear scale 43 pointer 67 controller (control device) 71 pressure control valve

Claims (3)

[Claims] 1. A work is provided by providing a fixed table and a ram capable of reciprocating movement opposite to the frame, and one die provided on the fixed table and the other die provided on the ram in cooperation with each other. In a bending machine for performing a bending process on, a screw pressurizing device and a hydraulic device for applying a pressing force during the reciprocating motion and the bending process of the ram, and a ram position detecting means for detecting the position of the ram, A rotation detecting means of a drive motor for driving the screw pressing device, and a first detection value detected by the ram position detecting means when the one die or the other die comes into contact with a work to be processed. And a control device having a plate thickness detecting function for detecting a difference between the second detection value detected by the rotation detecting means and the second detection value as a plate thickness of the work. Machine. 2. The bending machine according to claim 1, wherein the screw pressure device, the drive motor, and the rotation detection means are provided on both sides of the ram in the frame. 3. The bending machine according to claim 1, wherein the ram position detecting means is provided on both left and right sides of the fixed table and the ram.