JPS59220216A - Apron flexure correcting device of press brake - Google Patents

Abstract

PURPOSE:To correct optionally a flexure of an apron in accordance with a working length of a material to be worked, by providing a flexure correcting oil pressure cylinder on the apron center part in a press brake, and providing a means for controlling this cylinder pressure. CONSTITUTION:An oil pressure cylinder 9 for correcting a flexure is provided on the center bottom part of one of an upper apron or a lower apron 3 of a press brake. A pressure P1 of a pipe L2 for feeding a pressurized oil to pressure mechanism use pressure cylinders 5, 7 of the lower apron 3 is detected by a pressure detector D, converted to an electric signal S1 and inputted to an operating circuit C. At the same time, an electric signal S2 which is set in accordance with a material to be worked, from a length setting device S is inputted, brought to subtraction processing, and a control signal S3 is sent to a pressure-reducing valve V. The pressure-reducing valve V supplies a pressurized oil of a pressure corresponding to this signal to a pipe L4 to the flexure correcting cylinder 9, and corrects a flexure of the apron 3. According to this device, a product can be bent without generating a ship-shaped one.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apron deflection correction device for a press brake that can correct the deflection amount of the central portion of an apron according to the length of a workpiece material.

In general, the oil J]:li structure that operates the moving apron to move up and down is attached to the type of press brakes on both sides of the moving apron.
When bending is performed using a material that resists bending, the properties of the material to be processed, such as its tensile strength, elastic limit, yield point, and elastic modulus, as well as its springback properties based on these characteristics, cause the horns that resist bending to appear as a drag force. , which has a significant impact on the finished product.

In other words, in press brake bending work that uses relatively long upper and lower dies, the force that presses the lower dies is applied to the lower dies. When the fixed apron is supported on both sides, the movable apron tends to warp downward and the fixed apron tends to warp upward near the left and right centers of the press brake during bending.

As a result, the movable apron and the fixed apron tend to move away from each other in opposite directions near the center, and the bent product becomes a so-called hanging product. The center part (=near J) is incompletely bent, causing warping in opposite directions near the center of the product.

Conventionally, as a countermeasure to this problem with scales, the central part of the moving nibron was made high to counteract the bending moment concentrated in medium heat. However, this method is based on the premise that the upper surface of the movable apron and the upper surface of the stationary apron are both horizontal, and ignores the bending resistance characteristics of the workpiece being bent. Furthermore, since a completely rigid body is impossible, for example, even if the warpage of the movable apron and fixed apron during the final bending process is corrected in advance, it may be possible to adapt to a certain value of bending resistance, but when the bending resistance is However, the tendency to become -Ctt1 type could not be prevented.

Furthermore, even if it is possible to prevent a product of a certain shape from being hung, when processing another product with a different length of the workpiece material, the amount of deflection of the apron will be jη, so the same It is desirable to be able to apply deflection compensation and prevent the occurrence of hanging in the processing of products of all shapes and sizes.゛This invention was made in view of such conventional problems, and in order to correct the amount of deflection of the apron according to the length of the workpiece material, a pressure control device is installed in a hydraulic cylinder in the center of the apron. The purpose of the present invention is to provide an apron deflection correction device for press brakes.

This invention will be explained in detail below along with embodiments shown in the figures.

FIG. 1 shows the entire press brake according to the present invention. In this press brake, an upper apron 1 with an upper mold is fixed at a predetermined height, and a lower apron 3 with a lower part is raised and lowered by hydraulic cylinders 5 and 7 provided on both sides, and the -L part You can approach and move away from Apron 1. A hydraulic cylinder 9 for deflection correction is provided at the center bottom of the lower apron 3.

A connecting rod 11 is attached to this hydraulic cylinder 9, and the outer end of the connecting rod 11 is connected to the lower apron 3, so that when the hydraulic cylinder 9 is driven, the upper surface of the lower apron 3 is convex upward. It can be warped as desired.

FIG. 2 shows a system diagram of an embodiment of the present invention. Pressure oil is sent to the hydraulic cylinder 5.7 for the pressurizing mechanism of the lower apron 3 through piping 1 and 2°L3 by a pump P, and the hydraulic cylinder 5.7 is driven up and down by this pressure oil. Further, to the hydraulic cylinder 9 for deflection correction, pressure oil is sent from the pump () through a pipe LIN and a variable pressure reducing valve V1, such as a proportional electromagnetic pressure reducing valve, pipe 4.

Here, the pressure P of the pressure oil supplied to the hydraulic cylinders 5 and 7 is
1. When the pressure of pressure oil supplied to the hydraulic cylinder 9 is P2, the pressure reducing valve P+-P2 is adjusted by J to the pressure reducing valve V. This adjustment is made as follows.

■) When the length does not change The relationship between the pressing force required for bending and the deflection of the part 1 bun 1 is proportional when the bending length does not change. For this purpose, the amount of pressure reduction x is kept constant with respect to the pressurizing force P+, and the pressurizing force P2 is also changed together with the pressurizing force P1. In other words, P+
-P2 = X (constant).

In Fig. 2, the pressure P1 of pipe 2 is detected by a pressure detector, converted to an electrical signal S1, and inputted to the calculation circuit C. At the same time, the length of the workpiece is determined from the length setting device S. The electrical signal S2 set according to the current value is also input to the arithmetic circuit C, and the arithmetic circuit C subtracts the electrical signals s1 and G2 and sends a control signal S3 to the pressure reducing valve V.
This is done by supplying pressure oil to the pipe L41 at a pressure corresponding to the signal.

(2) When the length changes When the bending length of the liquid I+, fl material changes, the length setting signal S2 from the length setting device S is changed. The length signal of this length setting device S may be manually set using a digital switch, for example, or may be preset by a microcomputer according to the bending length for automatic numerical control. It is also possible to incorporate the system so as to output a signal.

In this way, the signal 53 (=Sl −
82), this time G2 has been changed, so it has a different value from the previous one, so the pressure reducing valve V has also been changed, and the deflection correction pressure P corresponding to the bending length has been changed.
2 will be obtained.

Specific examples of the amount of pressure reduction depending on the bending length are as follows.

Bending length Reduced pressure m 2 rn or less...P+ = P22,
5 m−−P+ −1〕2 =20kg
/ (nm23?++++++・mPI P2=40k
(+/C11122~2.5-m, between 2.5~3m, the amount of pressure reduction is proportional to the length).

FIG. 3 shows another embodiment of the invention.

In this embodiment, in order to bend the center part of the lower apron 3 into a convex shape according to the deflection of the upper apron 1, the strain detector SG
I and SG2 are respectively upper apron 1 and lower apron 3.
and an image distortion detector SGI.

The central part of the lower apron 3 is bent by a hydraulic cylinder 9 so that SG2 maintains a constant relationship.

Distortion detector SG1. The distortion detection signal from SG2 is sent to amplifier A1.
11111. Increased by A11lρ2 -C comparator Cmp
is input, and here the distortion of the upper apron 1 becomes thick tf
In order to increase the strain on the lower apron 3, a signal is generated to reduce the amount of pressure reduction from the pressure reducing valve V and is input to the pressure reducing valve V via the amplifier Am113. Conversely, if the strain on the upper apron 1 is small, the pressure reducing valve is increased accordingly, and a large amount of pressure reduction is commanded 4 to reduce the strain on the lower apron 3.
A signal is generated and input to the pressure reducing valve ■.

Even in this embodiment, if the bending length of the workpiece material is short, the deflection strain of the upper apron 1 will be large, and if the bending length is long, the deflection strain will be small.
This allows the amount of deflection of the C lower apron 3 to be corrected.

This invention is not limited to the above-mentioned embodiment, and for example, the following modifications are also possible.

(A> Instead of the pressurizing hydraulic cylinders installed on both sides of the apron, use an external force mechanism using a crank or gears.

(B) A hydraulic cylinder for pressurizing the apron shall be provided on the upper apron.

(C) A hydraulic cylinder shall be installed in the upper apron to correct the deflection in the center of the apron.

(D> Hydraulic cylinders for pressurization and correction should both be provided on the upper apron side.

As explained in detail above, in this invention, a hydraulic cylinder capable of pressure adjustment is provided to correct the deflection of the coniburon, so that when the bending length of the workpiece material changes and the deflection form of the apron changes. However, the deflection of the apron can be corrected at will. Therefore, in this invention, the product can be bent without being hung.

[Brief explanation of the drawing]

FIG. 1 is a front view of a press brake used in an embodiment of the present invention, FIG. 2 is a system diagram of an embodiment of the invention, and FIG. 3 is a system diagram of a third embodiment of the invention. 1. Upper apron 3. Lower apron 5.
...Hydraulic cylinder 7...Hydraulic cylinder 9...
Hydraulic cylinder 11 for deflection correction...Connection rod L+, L2, L3, L4...Piping D...Pressure detector C...Arithmetic circuit S...Length setting device
V...Pressure reducing valve SG1. SG2...distortion detector

Claims (6)

[Claims] (1) A press brake that has an upper apron and a lower apron opposing the upper apron, and in which one apron approaches and moves away from the other apron by a pressurizing mechanism provided on both sides, At least one of the aprons is provided with a deflection correction hydraulic cylinder in the center thereof that can be adjusted in pressure, and is also equipped with a pressure control device that controls the pressure of this hydraulic cylinder in accordance with the machining length of the workpiece material. Press brake apron deflection correction device. (2) The press brake apron IC deflection correction device according to claim 1, wherein the apron pressurizing mechanism 11 is a hydraulic cylinder. (3) The press brake according to claim 1 or 2, wherein the pressure J control device is a variable pressure reducing valve installed in an oil passage of a deflection correction hydraulic cylinder. Apron deflection correction device. (4) The pressure control device automatically adjusts the pressure reduction amount of the pressure reducing valve by calculating the oil pressure detection signal of the pressure mechanism hydraulic cylinder and a set value signal set according to the length of the liquid addition IOfil. 4. The press brake apron deflection correcting device according to claim 3, wherein the apron deflection correction device of claim 3 is adapted to control the apron deflection. (5) The pressure control device detects and compares the deflection distortion of the upper apron and the lower apron, and controls the pressurizing force of the deflection correction hydraulic cylinder so that the deflection amounts of both aprons match. An apron deflection correction device for a press brake according to claim 1 or 2, characterized in that: (6) The press brake apron deflection correction device according to claim 5, wherein a variable pressure reducing valve is used to adjust the pressure applied to the deflection correction hydraulic cylinder.