JPH05293550A - Method and device for bending by work bending machine - Google Patents

Abstract

PURPOSE:To improve bending accuracy by estimating disturbances from pressure and the speed or displacement of a lower table by means of a trial bending, calculating a pressure to obtain the final bending angle and outputting a pressure command. CONSTITUTION:The lower table is driven by a hydraulic cylinder, a work is held between the upper table and the lower table, and a bending is performed. The disturbances are estimated from the pressure and the speed or the displacement of the lower table by means of the trial bending. Data for characteristics between the bending force and the displacement of the lower table at the time of bending the work are collected and compared; the pressure to obtain the final bending angle is calculated, the pressure command is outputted, and the pressure of the cylinder is controlled. The bending angle of the work is not influenced by oil temperature, ambient temperature, thickness of the work, and characteristics of material; and thereby the accuracy of bending is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending apparatus and a bending apparatus for a work bending machine, which realizes a bending machine in which a bending angle of a work does not depend on an oil temperature and an environmental temperature in a bending machine such as a press brake. ..

[0002]

2. Description of the Related Art Conventionally, a press brake is provided with a plurality of fluid pressure cylinders between a cover and a cover provided on the front surface of a machine base, and a central fluid pressure cylinder is a main cylinder for rapid ascent and a left and right fluid pressure cylinder. Is a slow-speed rising sub-cylinder. A lower table driven by the main cylinder and the sub cylinder is provided, and a die is mounted on the upper surface thereof. An upper table is erected on a side plate which is erected right and left above the machine base, and a punch is attached to the lower surface thereof.

FIG. 12 shows a hydraulic circuit diagram of a conventional press brake. The hydraulic circuit is mainly composed of the main cylinder 1, the sub-cylinder 3, the upper limit valve (pressure control valve) 5, the solenoid valve 7 for slow speed, the solenoid valve 9 for quick speed, the check valves 11, 13, 15, the pump 17, the lower table 19 and the like. Become.

The solenoid valve 15 is switched to the solenoid valve 7, the sub-cylinder 7 is raised slowly, the work is clamped by the punch and the die, and bending is performed.

At this time, the displacement Xs of the lower table 19 pushes the spool 5a of the upper limit valve 5 to control the flow rate Q. This causes a valve pressure difference ΔP,
The lower table 19 is stopped by the displacement of the lower table 19 in which the force of (P−ΔP) · A (where A is the cross-sectional area of the cylinder) and the reaction force of the bending work are balanced. The bending angle of the work is determined by such a series of hydraulic operations.

Next, the operation from the rapid rise to the stop of the lower table 19 will be described. (1) Switching from the rapid rise to the slow rise by switching the solenoid valve 7.

(2) At the time of switching, the valve pressure difference Δp of the rising valve 5 is small. Therefore, the bending force is
The force for raising the force is larger than the reaction force due to the bending of the work, and the lower table 19 rises.

(3) As the lower table 19 rises, the spool 5a of the upper limit valve 5 is displaced, and the valve pressure difference ΔP of the upper limit valve 5 increases.

(4) As the valve pressure difference ΔP increases, the bending force decreases. The displacement of the lower table 19 in which the bending force (the force that raises the table 19) and the bending reaction force are balanced is set.

[0010]

However, the conventional bending method has the following problems.

(A) Since the valve pressure difference ΔP of the upper limit valve 5 is a function of the displacement Xs of the spool 5a, the oil temperature, and the kinematic viscosity, the valve pressure difference ΔP changes greatly as the oil temperature changes. To do.

(B) The Coulomb frictional force of the cylinder changes due to the change of the oil temperature.

(C) The frame of the press brake expands and contracts due to changes in environmental temperature. Therefore, the lower table 19
Since the displacement Xs and the feedback are used as the opening degree command of the spool 5a of the upper limit valve 5, the bending angle of the work changes.

(D) It is not possible to consider the work thickness and material properties.

Due to such a problem, when the environmental temperature and the oil temperature change, the bending angle of the work changes accordingly, and the variation of the plate thickness and the material characteristics of the work affects the bending angle. It was difficult to obtain the bending angle.

The object of the present invention is to improve the above-mentioned problems, and the working accuracy is improved without the bending angle of the work being influenced by the oil temperature, the environmental temperature, the plate thickness of the work, and the material characteristics. A bending method and apparatus for a work bending machine.

[0017]

To achieve the above object, the present invention provides an upper table provided on a machine base, a punch provided on a lower surface of the upper table, and a hydraulic pressure provided on the machine base. A lower table driven by a cylinder, a die that is provided on the upper surface of the lower table and sandwiches and bends a work between the punch, and a tip portion that is provided close to the lower table, and the lower table is displaced. A lower table having a pressure control valve for controlling the flow rate by pushing the tip end portion, and a force obtained by multiplying the pressure of the cylinder generated by the change in the flow rate by the cross-sectional area and the reaction force of the bending work are balanced. In the work bending machine that stops the lower table with the displacement of, the disturbance is estimated from the pressure and the speed or displacement of the lower table by trial bending,
Characteristic data of bending force and lower table displacement is collected during bending of the work, and characteristic data of pressure and lower table displacement is collected during work bending. Characteristics of bending force and lower table displacement obtained by a position command mode. Comparing with the data, calculate the pressure to obtain the final bending angle, calculate the pressure correction value based on the plate thickness and material characteristics, output the pressure command in the pressure command mode to obtain the final bending angle, and feed back the cylinder. Is a bending method for a work bending machine, which is characterized by compensating for a deviation from the pressure and controlling the pressure.

According to another aspect, a trial is performed in which a disturbance is estimated from a pressure and a velocity or displacement of the lower table by trial bending, and characteristic data of bending force and lower table displacement is collected during bending of the work. Characteristic data of bending mode and pressure and lower table displacement during work bending are collected, and compared with the characteristic data of bending force and lower table displacement obtained in the trial mode, the pressure correction value according to the plate thickness and material characteristics And a pressure command mode in which a pressure command is used as a pressure command to obtain the final bending angle; and a deviation between the pressure command of the position pressure command unit and the pressure causing the flow rate change fed back is compensated. A bending apparatus for a workpiece bending machine, comprising: a pressure control unit that applies pressure to the pressure control valve via a compensator to control the pressure.

[0019]

By adopting the bending method and apparatus for the work bending machine of the present invention, the disturbance is estimated from the pressure and the speed or displacement of the lower table by the trial bending, and the bending force and the lower portion during bending the work. Collect the characteristic data of the table displacement and collect the characteristic data of the pressure and the lower table displacement when bending the work.Compare with the characteristic data of the bending force and the lower table displacement obtained by the position command mode to determine the final bending angle. The pressure command mode that calculates the pressure to obtain, calculates the pressure correction value based on the plate thickness and material characteristics, and outputs it as the pressure command to obtain the final bending angle compensates for the deviation from the fed-back cylinder pressure. By controlling, the bending angle of the work is the oil temperature,
The processing accuracy is improved without being affected by the ambient temperature, the work thickness, and the material characteristics.

[0020]

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

FIG. 11 is a front view of a hydraulic press brake embodying the present invention. In the figure, the hydraulic press brake 21 is provided with a hydraulic control device 23 having a built-in computer, a push button device 25 and a foot switch 27 at the left end of the drawing.

The press brake 21 is provided with a front cover 29 on the front surface of the machine base, and a plurality of fluid pressure cylinders 1 and 3 as shown in FIG. 1 are provided between the machine base and the front cover 29.
The central fluid pressure cylinder is the main cylinder 1 for rapid rise,
The fluid pressure cylinders on the left and right are assumed to be slow rising cylinders (for bending).

A die 31 is fixed to the upper surface of the lower table 19 driven by the main cylinder 1 and the sub-cylinder 3, and an upper table 37 is mounted on the side plates 33 and 35 standing upright on the left and right sides of the machine base. It is fixed, and the punch 39 is fixed to the lower surface thereof.

FIG. 1 shows a control block diagram of an embodiment of the bending apparatus of the present invention. In the figure, the control device 23
The control circuit includes a pressure sensor 41, a cylinder / cross-sectional area multiplier 43, a lower table / die weight calculator 45, a work bending reaction force calculator 47, and a cylinder coulomb friction force calculator 4.
9, a 1 / ms calculator 51, a 1 / s calculator 53, a table displacement detector 55, and a position / pressure command section 57 and a pressure control section 59 which are features of the present invention. Here, m is the mass of the movable part, and s is the Laplace operator.

The position / pressure command section 57 is formed of two modes, a position command mode (trial bending mode) and a pressure command mode (pressure trace mode).

As shown in FIG. 2, in the position command mode, P
The operator bends the ID calculator 61 (the lower table 19
Input displacement amount), and the control device 23 controls the lower table 1
Input 9 displacement command pattern.

At the time of a rapid rise, the pressure (P-ΔP) and the lower table speed vt (or the displacement vr) are used to determine the lower table / die self-weight calculation Fw and the cylinder coulomb friction force calculator by the lower table / die self-weight calculator 45 Estimate the cylinder Coulomb friction force Ff by 49.

Further, as shown in FIGS. 3 and 4, pressure and table displacement data are collected when the work is bent.
Here, a and b are points where the molds 31 and 39 hold the work.

As shown in FIG. 5, the lower table / die self-weighting Fw and the cylinder coulomb frictional force Ff.
Is estimated, the bending force-table displacement characteristic c can be obtained from FIGS. 3 and 4.

Next, as shown in FIG. 6, in the pressure command mode, the pressure pattern trace transmitter 63 is provided, and the pressure-time characteristic not collected in the position command mode is set to the pressure command P.
Output as c.

At the time of rapid rise, depending on the cylinder pressure (P-ΔP) and the lower table speed vt (or displacement vr),
The lower table / die self-weight calculation Fw by the lower table / die self-weight calculator 45 and the cylinder coulomb friction force Ff by the cylinder coulomb friction force calculator 49 are estimated.

Further, as shown in FIGS. 7 and 8, pressure and table displacement data are collected when the work is bent.

As shown in FIG. 9, the bending pressure-lower table displacement data d when the work is bent are collected according to FIGS. 7 and 8, and the bending force obtained in the position command mode-lower portion as shown in FIG. It should be compared with the table displacement characteristic c (FIG. 5).

In this bending pressure-lower table displacement characteristic, the inclination K and the pressure difference P1 are compared to calculate the cylinder pressure (P-ΔP) for obtaining the final bending angle from this database.

This cylinder pressure (P-ΔP) is added to the pressure for compensating the lower table 19, the die weight Fw and the Coulomb frictional force Ff, and is output to the pressure controller 59 as a pressure command Pc.

In the pressure controller 59, the pressure command Pc is fed back from the pressure sensor 41 to the cylinder pressure (P
The deviation from −ΔP) is compensated by the compensator 65 and input to the pressure control valve 5. The valve pressure difference ΔP output from the pressure control valve 5 is fed back to the pump pressure P.

As described above, the present control circuit serves as a minor loop for the position / pressure command section 57 and the pressure control section 59.
By mounting, it becomes possible to control the pressure without being influenced by the oil temperature and the kinematic viscosity, and to realize highly accurate bending.

Further, since a trial bending by a skilled worker is performed and the pressure curve is accurately traced, even an inexperienced worker can realize high-precision bending at the same level.

Since the bending is performed based on the bending force-lower table displacement data, high precision processing can be realized even if the bending machine is thermally deformed.

Further, since the plate thickness and material characteristics (Young's modulus, etc.) of the work can be calculated from the bending pressure-lower table displacement characteristics and the database and the pressure control can be corrected, the plate thickness of the work High-precision bending can be realized even if the material characteristics change. Furthermore, the Coulomb friction force of the hydraulic cylinder, which changes with temperature, is estimated for each bending process, and high-precision bending is performed by compensating for this. Is possible.

The present invention is not limited to the above embodiments, but can be implemented in other modes by making appropriate design changes.

[0042]

As is apparent from the above description, the working method and apparatus for the work bending machine of the present invention estimates the disturbance from the pressure and the speed or displacement of the lower table by trial bending, and Characteristic data of bending force and lower table displacement is collected at the time of bending, and characteristic data of pressure and lower table displacement is collected at the time of work bending. Characteristic data of bending force and lower table displacement obtained by the position command mode. Cylinder pressure fed back by the pressure command mode that compares and calculates the pressure to obtain the final bending angle, calculates the pressure correction value based on the plate thickness and material characteristics, and outputs it as the pressure command to obtain the final bending angle. By compensating for the deviation from and controlling the pressure, the problems of the prior art are effectively solved, and the bending angle of the work is the oil temperature,
The processing accuracy is improved without being affected by the environmental temperature, the work thickness, and the material properties.

[Brief description of drawings]

FIG. 1 is a control block diagram of an embodiment of a bending apparatus of the present invention.

FIG. 2 is a block diagram of a position command mode in the position pressure command unit of FIG.

FIG. 3 is a pressure diagram when the work of FIG. 2 is bent.

FIG. 4 is a displacement diagram of a lower table when the work of FIG. 2 is bent.

5 is a bending force-lower table displacement characteristic diagram according to FIGS. 3 and 4. FIG.

FIG. 6 is a block diagram of a pressure command mode in the position pressure command unit of FIG. 1.

FIG. 7 is a pressure diagram when the work of FIG. 6 is bent.

FIG. 8 is a lower table displacement diagram when bending the work of FIG. 6;

9 is a bending pressure-lower table displacement characteristic diagram according to FIGS. 7 and 8. FIG.

FIG. 10 is a comparison diagram of bending force-lower table displacement characteristics in a position command mode and bending pressure-lower table displacement characteristics in a pressure command mode.

FIG. 11 is a front view of a hydraulic press brake embodying the present invention.

FIG. 12 is a hydraulic circuit diagram of a conventional press brake.

[Explanation of reference numerals] 1 main cylinder 3 sub cylinder 5 pressure control valve 19 lower table 21 press brake 23 controller 31 die 39 punch 57 position / pressure command section 59 pressure control section 61 PID compensator 65 compensator

Claims (2)

[Claims] 1. An upper table provided on a machine table, a punch provided on a lower surface of the upper table, a lower table provided on the machine table and driven by a hydraulic cylinder, and an upper table provided on the lower table. A die for sandwiching and bending the work between the punch and the punch; and a pressure control valve for controlling the flow rate by providing a tip portion close to the lower table and pushing the tip portion by displacement of the lower table. In a work bending machine, which has a lower table displacement due to displacement of the lower table having a force obtained by multiplying the pressure of the cylinder by the change in the flow rate and the cross-sectional area and the reaction force of the bending work Distortion is estimated from the pressure and the velocity or displacement of the lower table by bending,
Characteristic data of bending force and lower table displacement is collected during bending of the work, and characteristic data of pressure and lower table displacement is collected during work bending. Characteristics of bending force and lower table displacement obtained by a position command mode. Comparing with the data, calculate the pressure to obtain the final bending angle, calculate the pressure correction value based on the plate thickness and material characteristics, output the pressure command in the pressure command mode to obtain the final bending angle, and feed back the cylinder. A bending method for a work bending machine, which is characterized by compensating for a deviation from the pressure of and controlling the pressure. 2. An upper table provided on a machine table, a punch provided on a lower surface of the upper table, a lower table provided on the machine table and driven by a hydraulic cylinder, and an upper table provided on the lower table. A die for sandwiching and bending the work between the punch and the punch; and a pressure control valve for controlling the flow rate by providing a tip portion close to the lower table and pushing the tip portion by displacement of the lower table. In a bending machine, which has the valve pressure difference caused by the change in the flow rate and the reaction force of the bending work balanced with the force obtained by multiplying the cross-sectional area of the cylinder by the displacement of the lower table; A position finger that estimates the disturbance from the pressure and the velocity or displacement of the lower table by means of the above, and collects characteristic data of bending force and lower table displacement during bending of the workpiece. Of the pressure mode and the lower table displacement during bending of the workpiece and the characteristic data of the bending force and the lower table displacement obtained in the trial mode are compared to obtain the pressure correction value based on the plate thickness and the material characteristic. A position pressure command section consisting of a pressure command mode which is a pressure command for calculating and obtaining a final bending angle; and a deviation from a pressure that causes a flow rate change fed back based on the pressure command of the position pressure command section is compensated. A bending apparatus for a work bending machine, comprising: a pressure control unit that gives the pressure control valve via a compensator.