JPS62274101A - Method for ram-positioning in hydraulic equipment - Google Patents

Abstract

PURPOSE:To insure a fixed positioning precision without relation to the change of a load by using, as a position command signal, a signal which is a present position signal with a position-deviation-correction signal added to, when a position-deviation the occurred on account of the load. CONSTITUTION:A target position signal theta and a present position signal l are compared at a processor 27, and when a load has changed and a position deviation epsilon1 has occurred at the target position signal theta, a position-deviation- correction value C1 is added to the present position signal l, which is outputted to a matching point 15 as a position command signal. By this, even if the load becomes large due to the changed length or thickness of a plate in positioning a ram in a hydraulic equipment, say, a press-brake, the ram can be positioned with a fixed precision without lowering a positioning precision. Accordingly, the bending precision of the plate can be ensured without relation to the load.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for positioning a ram in a hydraulic machine;
More specifically, the present invention relates to a method for positioning a ram in hydraulic equipment, in which when a positional deviation occurs due to a change in the load applied to the ram, a correction process is automatically performed for positioning.

[Prior Art] Conventionally, a ram supporting a mold in a hydraulic device such as a press brake is moved up and down by a hydraulic cylinder that is a pressurizing cylinder attached to a side frame. The positioning for moving the ram up and down is performed by position feedback control using a hydraulic control valve such as a servo valve or a proportional switching valve and a displacement converter. That is, feedback control is normally used in which a target position signal is compared with a current position signal of the ram, and a hydraulic control valve is driven based on the difference between the two.

[Problems to be Solved by the Invention] However, in the conventional feedback control of the position of the ram J3 described above, when the length and thickness of the plate material to be machined changes and the load changes and increases, the target position signal described above The problem is that the difference between the current position signal of the ram and the current position signal of the ram becomes large, resulting in a decrease in positioning accuracy.

The purpose of the present invention was proposed in order to solve the problem in view of the above circumstances, and is to provide a method for positioning a ram in hydraulic equipment that can ensure constant positioning accuracy regardless of changes in load. .

[Means for Solving the Problem] In order to achieve the above object, the present invention uses a hydraulic control valve and a displacement converter to control the ram of a hydraulic device, and compares the target position signal θ and the current position signal of the ram, and calculates the difference between the two. In a feedback control circuit that drives a hydraulic control valve based on the difference, when a position deviation εn occurs due to the load, a position deviation correction 1aCn=K·εn (where K: constant) is added to the current position signal statement as a position command signal. This is characterized in that the positioning control of the ram is performed by performing arithmetic processing so as to output the ram.

[Operation] By adopting the present invention, when positioning a ram in a hydraulic device such as a press brake, even if the length or thickness of the plate material changes and the load increases, the ram can be positioned with a constant accuracy without reducing the positioning accuracy. You can position it with Therefore, the bending accuracy of the plate material can be ensured regardless of the load.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

Referring to FIG. 1, a fixed table 5 is attached to the lower part of side frames 3R, 3L of a press brake 1, which is an example of a hydraulic device. On the fixed table 5, a die holder 7 extending in the left-right direction in FIG. D is installation.

On the other hand, hydraulic cylinders 9R19L, which are pressure cylinders, are attached to the upper parts of the side frames 3R and 3L, respectively. A piston rod 11R111L is provided at the lower end of the hydraulic cylinder 9R19L. The lower ends of the piston rods 11R, 11L are attached to shoulders 15R115F on both sides of the ram 13. A punch P, which is an upper mold extending in the left-right direction in FIG. 1, is attached to the lower part of the ram 13 via a support member 17 extending in the left-right direction in FIG.

With the above configuration, when the plate material W to be pressed is placed on the die D and the hydraulic cylinder 9R19L is operated, the ram 13 moves up and down. Since the punch P is attached to the lower part of the ram 13 via the support member 17, the punch P moves up and down as the ram 13 moves up and down, and the plate material W is pressed by the punch P and the die D.

The ram 13 is positioned when pressing the plate material W. The positioning of the ram 13 in this embodiment is performed by the second
The positioning is controlled by a positioning feedback control circuit 1 as shown in the figure.

In one positioning feedback control circuit shown in FIG. 2, a servo valve 21, which is a hydraulic control valve, is connected to the hydraulic cylinder 9R19L. In front of the servo valve 21, an amplifier 23 and an arithmetic processing unit 27 are connected via a summing point 25.

On the other hand, the piston rod 11R of the hydraulic cylinder 9R19L
The ram 13 attached to 111L is connected to a displacement meter 27 which is a displacement converter. The displacement meter 27 is connected to the arithmetic processing unit 27 and the summing point 25, respectively.

With the above configuration, the target position signal θ is processed by the arithmetic processing unit! The current position signal of the ram 13 output from the displacement meter 27 is input to the arithmetic processing unit 27. The arithmetic processing unit 27 compares the target position signal θ and the current position signal A. For example, when the load changes and a positional deviation ε1 occurs in the target position signal θ, a positional deviation correction value C1 is added to the current position signal input to the arithmetic processing unit 27, and the resultant signal is output as a position command signal and the addition point is 25.

Note that the positional deviation correction value C+ is processed by the calculation Ha device 27 as C+=K·C1 (K: constant). Since the current position signal intersection of the ram 13 has already been taken in, the arithmetic processing of (tl+c+)-hair is performed at the addition point 25, and the correction value C1 of the position command signal is output to the amplifier 2.
Hydraulic cylinder 9R1 by controlling servo valve 21 through
The positioning of the ram 13 is corrected by changing the oil pressure of 9L. If a new positional deviation ε2 occurs even after this correction, C2=: ε2 (K: constant)
The arithmetic processing unit 27 performs the calculation of the position deviation correction 1ilIC2.
Then, add C2 to the position command signal A and perform the same processing. FIG. 3 shows the position deviation correction values ε1 and C2 of the current position signal of the ram 13 and the correction values C1 and C2 of the signal position command signal with respect to the processing time.

By repeating this operation, as shown in Figure 3, the position deviation ε
When 0 falls within the allowable range value Δθ of the target value signal θ, the positioning of the ram 13 has been corrected, and the positioning is completed. In other words, the current position signal is changed to C0-K・εn (K: constant) until ○≦εn≦Δθ.
This is to perform correction control.

[Effects] As can be understood from the above description of the embodiments, according to the present invention, when a positional deviation occurs due to a load, the arithmetic processing device is used to correct the positional deviation value of the current position signal of the ram. Because of this, the position of the ram can be controlled. Therefore, the ram can be positioned at a constant level regardless of the magnitude of the load. As a result, in the case of press brakes for hydraulic equipment, for example, bending accuracy can be ensured regardless of the length or thickness of the plate material.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of a press brake to which the present invention is applied. FIG. 2 is a schematic diagram of a ram positioning feedback control circuit illustrating the present invention. FIG. 3 is an explanatory diagram showing the correction state of each position signal with respect to the time during which the ram positioning correction is performed. [Explanation of symbols representing main parts of the drawings] 1...Press brakes 9R, 9L...Hydraulic cylinders 11R111L...Piston rod 13...One ram...Positioning feedback control circuit 21...
Servo valve 25... Addition point 27... Arithmetic processing unit 29... Displacement meter 1st

Claims (2)

[Claims] (1) A feedback control circuit that moves the ram of hydraulic equipment using a hydraulic control valve and a displacement converter to compare the target position signal θ and the ram's current position signal l, and uses the difference between the two to drive the hydraulic control valve. When a deviation εn occurs, a position deviation correction value Cn=K・ is added to the current position signal l as a position command signal.
A method for positioning a ram in hydraulic equipment, characterized in that the positioning of the ram is controlled by performing arithmetic processing such that εn (K: constant) is added and output. (2) When the allowable range of the target position signal θ of the ram is Δθ, the position correction of the current position signal Cn=K·εn (where K: constant) is repeated until 0≦εn≦Δθ. A ram positioning method in a hydraulic device according to claim 1, characterized in that: