JPS63174725A - Press brake with displacement sensor for electrical output - Google Patents

Abstract

PURPOSE:To quickly and precisely perform a control by fitting a linear actuator on a lower die, outputting a signal by measuring the gap between the movable tip part of this actuator and an upper die and controlling a hydraulic cylinder. CONSTITUTION:A differential transformer type displacement gage 71 is fitted to the movable tip part 51 of a linear actuator 50 to move the linear actuator 50 vertically. The output of the differential transformer 71 is converted into a DC signal by a convertor 72 to drive a servovalve 60 and to vertically move a hydraulic cylinder 40. When the differential transformer 71 is pushed up by the actuator 50, the differential transformer 71 detects that the distance (d) is shortened by its abutting to a bar 70, the servovalve 60 is worked with the signal thereof to lift a ram plate 30 via the hydraulic cylinder 40 and the distance (d) is made constant at all times. The distance D of the upper die 11 and lower die 12 thus varies simultaneously with the movement of the differential transformer 71. Consequently the control of a power cylinder becomes quick and precise.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates generally to mechanical presses, and more particularly to press brakes with linear actuators.

In particular, it relates to press brakes that use displacement sensors with an electrical signal output to detect the position of the ram plate.

(Prior Art) Press brakes used for sheet metal bending and the like require extremely high accuracy in controlling the position of the ram plate.

For example, a side view of this area shown in FIG. 2 (FIG. 1 will be shown later because it is based on the present invention).

A plate such as iron plate 20 is sandwiched between the upper mold 11 and the lower mold 12.

A bending angle of 90'' is normally obtained by pressing as shown in Figures 2a-2b.

This press requires extremely high precision, so that even an error of ±0.5° with respect to the target angle of 90° will result in a failure.

Therefore, this upper type! l press position control is 9 usually 1/1
Accuracy with an error within 0.00 mm is required. On top of that, a large amount of power is required when bending a wide board. Therefore, as shown in the front view shown in Fig. 3, in this case, the common method is to apply pressure to both sides of the ram plate 300 with hydraulic cylinders 40 to push it down (of course, on the contrary, the upper mold 11 is fixed and lowered). Some push up the mold 12). Then, highly accurate synchronized operation of the left and right cylinders 41 and 42 is required. Furthermore, when a workpiece (workpiece) is sandwiched between the upper die 11 and the lower die 12, it is normal for the workpiece to shift to either the left or right, but if it shifts, it will become a one-sided load. Therefore, since the load is no longer applied equally to the left and right cylinders 41 and 42, it becomes extremely difficult to perform left and right synchronized operation (position control).

Furthermore, there are times when it is desired not only to bend the workpiece plate 20 at an even angle, but also to change the bending angles on the left and right sides, as shown in the perspective view of FIG. in this case,
Pressure must be applied (synchronous operation of cylinders 41 and 42) with the ram 30 tilted as shown in the front view shown in FIG.

(Problem to be Solved by the Invention) Such control generally involves detecting the movement (displacement) of the ram plate 30 using a linear scale and performing feedback back to a servo valve or proportional control valve for controlling the cylinders 41 and 42. This is possible by doing this. If this is done using an analog method, the control will be fine, but the distance will be 1/100m over the entire stroke.
It is not easy to maintain the accuracy of m. Also, if you go digital.

Normally, a microcomputer is used to judge the displacement and control the cylinder, but if the computer is used to read the displacement in detail up to the limit of the resolution of the linear scale, it takes time to judge and control, and the cylinder movement is proportional to that. The speed will also decrease. If you ignore this and skip reading the data from the linear scale, it will be the same as making the resolution of the linear scale coarse, and the synchronized operation of the left and right cylinders will become incomplete.

Additionally, a device having a mechanical feedback mechanism as shown in the front view shown in FIG. 6 has also been announced. The method is to use a linear actuator 50 (for example, a combination of a rotary encoder, a servo motor, a ball screw, etc.) to push the plunger of a 4-boat switching valve 60 to switch boats.

Thereby, the hydraulic cylinder 40 is operated to cause the ram plate 30 to follow. In short, the ram plate 20 is caused to follow the movement of the linear actuator 50 using a mechanical feedback mechanism.

However, this method has the disadvantage that it is very difficult to switch boats due to minute displacements of the plunger. In order to cope with minute displacements, the mechanical precision of the spool and boat must be extremely improved, or the movement of the linear actuator must be increased using the principle of leverage. However, if the lever mechanism is brought to such a location, it will become extremely unstable due to initial adjustments and changes over time.

Furthermore, in the case of mechanical feedback servo control, it is not possible to adjust the feedback loop gain during operational testing. Even if a mechanical mechanism were considered, it would be complicated and would always suffer from problems such as deterioration over time. Furthermore, when the plate material is actually bent by performing a pressurizing operation, the jaws of the frame 6 shown in the side view shown in FIG. 7 open due to the strong pressurizing force, so the cylinder 40 must be pushed down by that amount.

This means that in order to accurately manage the actual distance between the upper die 11 and the lower die 12, it is necessary to know in advance the way the jaws of the frame 6 open as data. Difficulties are always present in terms of control.

(Means for Solving the Problems) The press brake with a displacement sensor for electric signal output according to the present invention has been developed in view of nine or more problems.

Completely synchronized operation of left and right cylinders 41 and 42.

Moreover, even when the ram plate 20 is tilted, the synchronous operation is not disrupted, and the control speed is further increased.

That is, in order to accurately bend a plate material in a press brake, it is necessary to accurately control the distance between the upper die and the lower die. Therefore, a linear actuator is attached to the lower die, the distance between the movable tip of the linear actuator and the upper die is measured by a displacement sensor, and the minute fluctuations in the gap are output as an electrical signal by a converter, which is transmitted to the servo amplifier. This control system is characterized in that the distance between the upper mold and the lower mold is kept constant by controlling the hydraulic cylinder.

Below, the specific configuration of the press brake with a displacement sensor for electric signal output according to the present invention will be described in detail.

First, there is a one-space foundation. Then there are displacement sensors that have an electrical signal output. This displacement sensor with an electrical signal output is provided opposite the spacing base. And there are a pair of types. One of the pair of molds is provided with either the spacing base described above or the displacement sensor described above.

Further, the other of the pair of types provides the remaining other of the spacing base or the displacement sensor through a linear actuator. Then, there is a servo amplifier that inputs the electrical signal output from the above-mentioned displacement sensor. Furthermore, there is a servo valve that is controlled by the output signal from this servo amplifier. Finally, there is a cylinder that is controlled by this servo valve. This cylinder is coupled to operate one of the pair of dies.

(Function) Since the press brake with a displacement sensor having an electric signal output according to the present invention is configured as above 9, the following effects occur.

First, a displacement sensor having a spacing base provided on one of a pair of molds and an electric signal output provided on the other mold determines whether the distance between the two molds is correct or incorrect. This displacement sensor then outputs an electrical signal depending on whether the displacement sensor is correct or not, which controls the servo valve through a servo amplifier. This then controls the cylinder. This cylinder is coupled to one of the pair of dies and moves it up and down.

The spacing base or the displacement sensor is coupled to one of the pair of molds, the linear actuator is provided on the other of the pair of molds, and the spacing base is coupled to the other of the pair of molds. or the other of the displacement sensors described above, by operating this linear actuator.

The position between the pair of dies can be controlled by the signal output from the above displacement sensor.

(Example) The press brake with a displacement sensor having an electric signal output according to nine embodiments of the present invention will be described in detail below using an example thereof together with the accompanying drawings showing the press brake.

FIG. 1 is a side view of an embodiment of a press brake with a displacement sensor having an electric signal output according to the present invention.

First, there is a pair of molds 11.12. The upper molds 11 of the pair of molds are provided with bars 70 serving as base portions at nine intervals. Further, the other of the pair of molds is held on a base 31. This base 31 is further coupled to a linear actuator 50. A displacement sensor 71 having an electrical signal output is provided at the tip 51 of the movable part of the linear actuator 50. The displacement sensor 71 having this electrical signal output is connected to the bar 7 mentioned above.
It is provided opposite to 0.

The electrical signal output from the displacement sensor is input to a converter 72, which is further injected into a servo amplifier 8.
Enter 0. And there is a servo valve 60. This servo valve 6o is controlled by the output signal from the servo amplifier 8°. lastly.

There is a cylinder 40. This cylinder 40 is controlled by the above-mentioned servo amplifier 80, and is coupled to move the above-mentioned pair of upper molds 1 through the ram plate 3o.

The bar 70 is not provided on the upper mold 11 side as in the nine embodiments, but is provided on the tip 51 of the movable part of the linear actuator 5o, and the displacement sensor 71 having the electrical signal output is connected to the top die 11 side. It may also be provided on the upper mold 11 side.

The operation of the press brake with a displacement sensor having an electric signal output according to the present invention will be described below.

First, the differential transformer type displacement meter 71 is attached to the movable tip 51 of the linear actuator 50, and the linear actuator 50 moves the differential transformer 50 up and down.

A bar 70, which is a protrusion, is provided on the ram plate 30 or the upper mold 11 so that the tip of the probe of the differential transformer 71 abuts against it. The output of the differential transformer 71 is transferred to the converter 7
2, the signal is converted into a DC signal, which drives the servo valve 60 via the servo amplifier 80 to move the hydraulic cylinder 40 up and down. When the differential transformer 71 is pushed up by the linear actuator 50, the differential transformer 71 detects that it hits the bar 70 and the distance d is shortened, and the servo valve 6o is moved by the signal and the ram plate 30 is moved through the hydraulic cylinder 40. pull up. Moreover, when the differential transformer 71 descends, the ram plate 3o also follows and descends. Therefore, the distance d is always constant.

As a result, the distance between the upper die 11 and the lower die 12 changes in synchronization with the movement of the differential transformer 71. When a pair of left and right linear actuators are provided, it is easy to electrically operate the left and right linear actuators in synchronization using current control technology. Therefore, the hydraulic cylinders that move following the left and right linear actuators are also operated synchronously. This means that the electrical control section such as a microcomputer only needs to precisely and rapidly control the linear actuator 50 without being aware of the hydraulic section such as the servo valve 60. The hydraulic section only operates by following the linear actuator 50 so that the distance d between the linear actuator 50 and the bar 70 is always constant due to the differential transformer 71. Moreover, by adopting such a structure, it is possible to automatically compensate for the opening of the jaws of the frame 6 (see Fig. 6) when a strong pressure is applied, and to constantly manage the distance between the upper mold 11 and the lower mold 12. It becomes possible to do so.

In this case, the same effect will occur even if the linear actuator 50 is attached to the upper die 11 and the bar 70 is attached to the lower die. Various combinations of these may be considered, including those mentioned above. In addition, although the differential transformer 71 is used in this embodiment to measure the distance d, it is not a contact type displacement meter, but an optical displacement meter.
A non-contact displacement meter using air or the like may be used.

In short, the control method of the present invention operates precisely and rapidly the linear actuator 50 attached to the upper mold 11 or the lower mold 12 in the electrical control section, and This control method is characterized by measuring the distance d to a measuring protrusion attached to the measuring protrusion 12, and operating the hydraulic cylinder 40 to keep the distance constant.

Note that the linear actuator 50 is a pulse encoder 52.
A combination of a servo motor 53 and a ball screw 54 is generally used, but any type that moves linearly and has the same accuracy as a linear scale may be used.

(Effects of the Invention) Since the press brake with an electric signal output displacement sensor according to the present invention has a configuration as described above, the power cylinder can be controlled quickly and precisely.

In other words, electrical control only needs to be able to precisely and rapidly control the linear actuator, and is not connected to the hydraulic section. Therefore, the electrical part and the hydraulic part can be adjusted separately, which saves a lot of manufacturing effort.

[Brief explanation of the drawing]

FIG. 1 is a side view of an embodiment of a press brake with a displacement sensor having an electric signal output according to the present invention. FIG. 2 is a side view of the vicinity of a pair of common molds, with FIG. 2a showing the mold before pressing, and FIG. 2b showing the mold during pressing. FIG. 3 shows a front view of the vicinity of a general ram plate. FIG. 4 is a perspective view of one embodiment showing the state of pressing the plate material. FIG. 5 is a front view of one embodiment of a general ram plate. FIG. 6 shows a front view of an example of the vicinity of a control section of a conventional press brake. FIG. 7 is a side view of an embodiment of a conventional press brake.

Claims (12)

[Claims] (1) a spacing base, a displacement sensor disposed opposite to the spacing base and having an electrical signal output; and one of a pair of types, the spacing base or the displacement sensor one that is provided with either one of the displacement sensors, one that is the other of the above-mentioned pair of types and that is provided with the other of the above-mentioned interval base or the above-mentioned displacement sensor through a linear actuator, and further the above-mentioned displacement sensor. a servo amplifier that inputs the output of an electrical signal from the servo amplifier, a servo valve that is controlled by the output signal from the servo amplifier, and a cylinder that is controlled by the servo valve and operates one of the above pair of types. A press brake with a displacement sensor that outputs an electric signal and is characterized by being configured with a displacement sensor. (2) The press brake with an electric signal output displacement sensor according to claim 1, wherein the interval base portion is a bar. (3) The press brake with an electric signal output displacement sensor according to claim 1, wherein the spacing base portion is provided on the upper molds of a pair of molds. (4) The press brake with an electric signal output displacement sensor according to claim 3, wherein the spacing base portion is provided through a ram plate between the upper molds of the pair of molds. (5) The press brake with an electric signal output displacement sensor according to claim 1, wherein the displacement sensor having an electric signal output is of a contact type. (6) The press brake with an electric signal output displacement sensor according to claim 5, wherein the displacement sensor having an electric signal output is a differential transformer. (7) The press brake with an electric signal output displacement sensor according to claim 1, wherein the displacement sensor having an electric signal output is of a non-contact type. (8) The press brake with a displacement sensor having an electric signal output according to claim 7, wherein the displacement sensor having an electric signal output is of an optical type. (9) The press brake with an electric signal output displacement sensor according to claim 7, wherein the displacement sensor having an electric signal output is of a magnetic type. (10) The press brake with an electric signal output displacement sensor according to claim 1, wherein the linear actuator is provided on the lower die of a pair of dies. (11) The press brake with an electric signal output displacement sensor according to claim 10, wherein the linear actuator is indirectly provided to the lower die of the pair of molds through a base. (12) The press brake with an electric signal output displacement sensor according to claim 1, wherein the linear actuator is a combination of a servo motor with a pulse encoder and a ball screw.