JPS60141400A - Positioning device for liquid pressure press - Google Patents

Abstract

PURPOSE:To perform stroke positioning with high accuracy while using inexpensive constituting members by comparing the intended and present values of the stroke lengths and speeds of right and left cylinders and controlling the same. CONSTITUTION:Comparing parts 13a, 13b for stroke lengths consist essentially of up-down counters which calculate the deviation between the distance pulses supplied from detecting pats 8a, 8b for the present stroke lengths and the distance pulses indicating the intended values in the respective operating conditions supplied from a setting part 11. The parts 14a, 14b are the comparing parts of the stroke speeds in said stage and the control signals of servocontrol driving parts 43a, 43b formed by the intended values in processing parts 12, 15a, 15b are corrected by the results calculated by both parts 13a, 14a as well as the same 13b, 14b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for operating a stroke operating part of a hydraulic press such as a press brake.

In hydraulic presses such as press brakes, where the upper table and ram are operated by two hydraulic cylinders on the left and right, the stroke operation of both the left and right hydraulic cylinders depends on their stroke resistance and stroke speed. must be symmetrical.

In particular, it is an essential requirement for this type of hydraulic press that the swivel/loaf positioning of the left and right cylinders be uniform on the left and right sides in order to ensure the operating accuracy of the press machine. Various methods are being used.

For example, (a) so-called linear gauges are installed on the left and right sides of the upper table ram to separately capture the strokes on the left and right sides of the table, and the hydraulic cylinders on both the left and right sides are controlled by the respective hydraulic servos until each stroke reaches the target value. Positioning can be performed by controlling the valves, or (b) limit switches can be provided at the positioning points on the left and right sides of the upper table, and the solenoid valves in the hydraulic circuits of each hydraulic cylinder can be switched by operating these switches. Stroke positioning is performed by (c) setting or changing the operating position of a mechanical valve.

However, the above method (a) lacks economic efficiency because the so-called linear gauges and hydraulic servo valves are expensive, and the method (b) can be implemented easily and at low cost;
The problem with method (c) is that positioning accuracy depends on the ram speed and the accuracy of the limit switch, making it difficult to perform highly accurate positioning, and that the stopping position is not the same due to the influence of oil temperature.

The present invention has been made in view of the current state of stroke positioning in hydraulic presses as described above, with the purpose of providing a control method that allows highly accurate stroke positioning using relatively inexpensive components. In a hydraulic press in which a ram is stroke-operated by left and right hydraulic cylinders, the hydraulic circuits of the left and right cylinders have -
A servo valve is inserted in which the valve chamber is partitioned in parallel with multiple on-off valves with different opening diameters, and each on-off valve is opened and closed by an actuator provided individually. A stroke amount detector that supplies a pulse signal corresponding to the unit movement amount is provided,
When both cylinders operate, each stroke amount is determined by a distance pulse signal, and each stroke speed is determined by a distance pulse/time pulse or a time pulse/distance pulse by corresponding a time pulse signal as appropriate to the distance pulse signal. The current value of the stroke position and speed at that time of both cylinders is detected by a speed pulse signal of the shape, and the positioning points including the deceleration and stopping points of both cylinders, as well as the speed of each stroker at each positioning point are detected. 1) can be set using a predetermined value expressed by or converted into a distance pulse signal and a speed pulse signal, and the stroke operation of both cylinders is controlled by a stroke claw and a stroke claw for each positioning point. Control is performed by the servo valve which is driven based on the result of comparing and calculating the planned value and the current value of the speed at that time, and at the same time, the current value of the stroke of both cylinders or the stroke amount of both cylinders is controlled. The present invention is characterized in that the servo valves of the respective cylinders are controlled by comparing the current value of the stroke speed with the current value of the stroke speed.

Next, an example of implementing the method of the present invention will be explained with reference to the drawings.
lb is a hydraulic cylinder installed on the left and right sides of the machine to move the ram downward in the press brake, 2 is a pump that supplies pressure oil to both cylinders la and lb, 2a is its drive motor, and 3 is a With piping, both the cylinders la and lb
Servo valves 4a and 4b, which will be described later, are installed between the pressure oil supply and discharge ports of
, switching valves 5a, 5b, regulating valves 3a, :3+), 3c
etc. are inserted to form a hydraulic circuit. In addition, 6 is an oil reservoir.

Thus, each of the cylinders], a, and lb rods 11a.

11b is connected to an upper table (not shown) equipped with a punch at the bottom via a ram (not shown), etc., and by supplying and discharging pressure oil to the cylinders la and lb, the punch is connected. Although the press operation is performed by stroke operation, the present invention uses the above-mentioned two cylinders Ia and Ib,
It is driven by a control system as described below.

This point will be explained below.

First, the servo valve 4ε" has a valve chamber 41a forming a part of the hydraulic circuit, which has a plurality of valves with different opening diameters. (not shown in the figure)), and each actuator 42a is provided with an actuator 42a that opens and closes individually for each actuator 42a. be. Similarly to the above valve /li, the servo valve 4b is also
1 valve chamber 4], a plurality of valves (not shown), an actuator 42b for each valve, and a servo l'+ moving part 4:3b.

Next, rod 1]+i, l for each cylinder la, lb
lb is a pulse signal corresponding to the stroke amount; for example, 1.111111 when these strokes are activated.
Strotor amount detector 7a that supplies 100 distance pulse signals per stroke.

7b is provided in the related number. As the stroke amount detectors 7a and 7b, an encoder-type pulse generating section is brought into contact with the rod lla and rotated by a roll called 1 rotation, and a pulse of 1j is generated every 1lpJ of the 1st position of the rod 1. Use one that generates a signal.

Incidentally, the above-mentioned detector may be installed in a part other than the rod as long as it is a part of the press machine that performs the rotating operation. Further, it goes without saying that the above-mentioned pulse signals are supplied correspondingly to each rod during its reciprocating stroke.

Therefore, the pulse signals supplied from the detectors 7a and 7b are transmitted from an arbitrarily determined origin point], 1a, 1],
The stroke speed of b. At the same time as indicating the current position, by associating the supplied distance pulse signal with an appropriate time pulse signal, for example, a form in which the distance pulse signal is made to correspond to a unit amount of time pulse signal. Alternatively, the current stroke speed of the roller 111) can be formed by a signal in the form of a time pulse signal corresponding to a distance pulse signal of a unit amount.

8a, 8b are supplied from the detectors 7a, 7b).

The current stroke amount detecting sections 9a, 9b which store one or more distance pulse signals sent to the current stroke amount detecting section 9a, 9b output the distance pulses supplied via the detecting sections 8a, 8b to the oscillator 10a, ]O.
A current stroke speed detection unit 11 detects the loaf speed of the current stroke speed in accordance with the time pulse supplied from b, and 11 indicates the operating status of both cylinders la and lb, such as acceleration and deceleration points including stop and their positions. The planned stroke speed of the setting section 11 is initially set by the processing section 12.
．． The control signals for the servo valves 4a and 4b are processed in the control signals 15a and 15b and supplied to the servo drive units 43a and 43b.
When b begins to operate, the stroke amount and its speed are corrected by signals formed from the results of comparison calculations between their current values and scheduled values.

That is, 13a and 13b indicate the current stroke amount detection section 8.
a.

4a, a stroker ratio 1 part, which mainly includes an up-down counter that calculates the deviation between the distance pulse supplied from 8b and the distance pulse supplied from the setting part 11 indicating a scheduled value in each operating state; Reference numeral 14b is a comparison section for the stroke speed at that time, and both comparison sections 13a, 1
Based on the calculation results of 4a, 13b and 14b, the control signals for the servo drive units 43a and 43b, which are formed by the predetermined values, are corrected in the processing units 12.15a and 15b.

In this way, both hydraulic cylinders la and lb are supplied with pressure oil from the same pressure oil supply source via servo valves 4a and 4b that are opened and closed to control the stroke amount and stroke speed for positioning. Therefore, fine operation control can be performed.

However, in large press brakes, etc., pressure oil is supplied from the same pressure oil supply source due to various factors such as response delay and increase in oil temperature due to the large cylinder capacity or large stroke. Even with this control, a difference may occur between the strokes of the left and right cylinders.

Therefore, in the present invention, the current positions of the left and right cylinders la and lb are compared, and if there is a deviation, it can be corrected.

That is, the distance pulses supplied from the stroke amount detectors 7a and 7b of both cylinders la and lb are constantly compared in the position comparison section 16, and this comparison section 1
Based on the calculation results in step 6, the processing section 12 generates a control signal that controls, for example, to throttle the servo valve of the advancing cylinder and to open the servo valve of the delayed cylinder.

In this way, the unevenness of the current positions of the left and right cylinders can be corrected, so that more effective positioning can be achieved by combining the fine positioning control described above according to the present invention.

From the above point of view, although the control system is not shown, the present invention is designed to prevent the left and right cylinders from moving at the same position during loaf operation, which is considered to be one of the causes of the unevenness of the current positions of the left and right cylinders. The stroke speeds of both cylinders may be compared to control the stroke speeds of both cylinders to be the same.

As a control system for the above, for example, the current stroke speed detection unit of both cylinders! The current speeds of both cylinders formed at λ and 9b are constantly compared at the same time as the position, and based on the speed deviation at the same position, the servo valve 4
Any device that corrects the control signals of a and 4b may be used.

As described above, the present invention is capable of controlling the stroke operation of a hydraulic press such as a press brake having hydraulic cylinders on the left and right sides, by determining the current stroke amount and the same speed of the left and right cylinders as planned values for each of them. Control is performed while comparing the current value, and at the same time, the current position of the left and right cylinders and, if necessary, the speed at that point. Positioning can be achieved. In addition, the configuration of the servo valve and strator sight detector required for this control,
In addition, since the configuration of the control system is extremely uM, the control device can be manufactured at low cost and maintenance is simple, making it extremely useful as a control method for hydraulic presses.

[Brief explanation of the drawing]

The figure is a system plotter diagram showing an example of a control system implementing the method of the present invention. la, 1b=hydraulic cylinder, 1. ]a, 1.1b
Lot, 2... Oil pump, 3. Piping, 4a, 4b. Servo valve, 7a. 7b... Stroke amount detector, 8a, 8b Current stroke amount detection section, 9a, 9b... Current stroke speed detection section, 11... Setting section, 12.15a, 15b.- Processing section, 13a, 13b- Stroke speed detection section. Comparison part, 1.4
a, 14b・Stroke speed comparison section, 16...Position comparison section representative Yoshikuni Koizumi

Claims (1)

[Claims] In a hydraulic press in which the ram is stroke-operated by left and right hydraulic cylinders, the - valve chambers are partitioned in parallel with a plurality of on-off valves with different opening diameters in the hydraulic circuit of the left and right cylinders, and each on-off valve is connected to A servo valve formed to be opened and closed by an actuator provided individually is inserted, and a stroke detector is provided in the stroke operation section of each cylinder to supply a pulse signal corresponding to the unit movement of the cylinder. When the cylinder operates, each stroke speed is determined by a distance pulse signal, and each stroke speed is determined by a distance pulse/lI;y pulse or a time pulse/distance pulse. Detected by a speed pulse signal in the form of
While detecting the current values of the S1 loaf position and the speed at that time of both cylinders, the positioning points including deceleration and stopping points of both cylinders, and each stroke speed at each positioning point are detected by the distance pulse signal. , and a planned value expressed by a speed pulse signal or converted into these, so that the stroke operation of both cylinders can be set using the planned value for the stroke amount and the speed at that time for each positioning point. At the same time, the control is performed by the servo valve, which is driven based on the result of comparing and calculating the current value of and controlling the servo valves of each cylinder by comparing current values of stroke speeds.