JPH0246998A - Method of controlling multislide press - Google Patents

Abstract

PURPOSE:To prevent the oscillation generated when the stroke of a ram is at a high speed by commanding an acceleration change to the driving part of a servo valve when the acceleration change of the stroke motion of a hydraulic cylinder increases too much. CONSTITUTION:A wire rod W is supplied by a feed mechanism 29 to a stage and is cut to a prescribed length. A die 10 holds the wire rod W on the stage. Dies 6-9 work the wire rod W under prescribed conditions. The die 6 is mounted to the hydraulic cylinder 1. A controller 26 emits the command so as to insert the slight time of acceleration zero when a detector 22 detects the rapid change in the stroke acceleration of the hydraulic cylinder 1. The command is received by a servo amplifier 17 which controls the servo valve 11 to adjust the supply rate of the pressure oil to the hydraulic cylinder 1, thereby controlling the movement of the die 6 and preventing the generation of the oscillation. The same control is executed to the dies 7-10 as well so that the control to obviate the generation of the oscillation in spite of movement of the stroke at the high speed is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a numerical control method for a multi-slide press using a plurality of hydraulic cylinders as pressure sources.

[Conventional technology]

A multi-slide press is used to manufacture deformable springs and the like with complex shapes by applying multiple steps of pressing to wire rods and plate materials.

This press performs multiple sliding processes.1 For example, multiple drums each having a cam profile formed on their inner surfaces are arranged radially with respect to the stage, and each drum is mechanically rotated. By reciprocating each slide of the press using tracers connected to the respective cam profiles, pressing operations such as bending and drawing are performed using dies connected to each slide.

[Problem to be solved by the invention]

Conventional multi-slide presses have the disadvantage that the drum, which has a unique cam profile, must be replaced every time the shape of the workpiece changes, making the so-called setup changeover process complicated and requiring 9 hours of manpower.

To address these difficulties, if a hydraulic cylinder is used as the drive source for a multi-slide press, it will be easier to change the machining shape, but with this drive system, the reciprocating speed of the hydraulic cylinder is slower than with a mechanical drive system. Therefore, even if it is possible to save labor in the changeover process, another drawback is that productivity is reduced.

In this case, if the hydraulic cylinder is driven at high speed, it is theoretically possible to create a multi-slide press that is comparable in productivity to a mechanical drive system using a cam profile, but in reality, Another problem is that vibrations are likely to occur due to stroke operation in which rapid acceleration and deceleration are repeated.

[Means to solve the problem]

The present invention aims to provide a control method that does not generate vibrations even when the stroke speed during reciprocating ram is driven at high speed in controlling a multi-slide press using a hydraulic cylinder as a pressure source. It was created and its composition is as follows:
When controlling the drive of a multi-slide press in which multiple molds driven by multiple hydraulic cylinders are arranged according to the shape of the workpiece, the opening and closing of each servo valve that controls the reciprocating motion of each hydraulic cylinder is controlled at the same time. When performing control at an appropriate sampling period, the acceleration of the stroke operation of the cylinder is appropriately detected by a detection means at the sampling period;
The present invention is characterized in that when the contents of the detected acceleration meet arbitrarily preset conditions, a control command for changing the detected acceleration is given to the opening/closing control section of the servo valve.

[For production]

The stroke operating state of each hydraulic cylinder is monitored by the acceleration of its stroke motion before and during machining, and when the acceleration is within a predetermined value, a command value indicating zero acceleration is inserted to suppress minute vibrations, etc. The speed of the stroke operation can be controlled at high speed.

[Example]゛ Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of essential parts of an example of a hydraulic cylinder type multi-slide press to which the method of the present invention is applied, and FIG. 2 is a stroke time diagram showing an example of stroke operation of each cylinder.

In Fig. 1, 1 to 4 are four hydraulic cylinders that are radial to the stage (not shown) and arranged to correspond to the machining shape of the workpiece, and 5 is orthogonal to the stage. Hydraulic cylinders arranged in the same direction, 1a to 5a are pistons of each cylinder, 1b to 5b are rods attached to each piston 18 to 5a, and molds 6 to 1o for processing are attached to the tip of each rod 1b to 5b. It is being Note that the number of installed hydraulic cylinders in the embodiment is merely an example, and in the present invention, the number of installed hydraulic cylinders is arbitrary as long as there is a plurality of hydraulic cylinders.

Flow rate proportional type servo valves 11 to 15 are connected to the pressure oil supply and discharge ports in each of the cylinders 1 to 5, and
Each servo valve 11 to 15 has its driving actuator, -11
activated by a-15a.

The stroke operation state of each piston 18 to 5a is driven and controlled.

Note that each of the servo valves 11 to 15 described above is connected to a pressure oil pump 16. Reference numeral 16a denotes a piping system for the pressure oil circuit of this pressure oil pump 16, and necessary parts such as a pressure sensor 16b, a regulating valve 16c, a check valve 16d, etc. are inserted into this system.

17-21 are pulse width modulation (PWM)
type of servo amplifier, each of the above actuators lla~
Controls the drive of 15a.

Reference numerals 22 to 25 indicate stroke amount detectors of the hydraulic cylinders 1 to 4. For example, a magnetic type length measuring device or the like is used to detect the stroke amounts of the piston rods 1a to 4a as pulse signals.

Each of the above amplifiers 17 to 21 is supplied with a pulse signal serving as a control command value from the digital controller 26, and among these amplifiers 17 to 20, addition/subtraction units 178 to At 20a, pulse signals detected by each of the detectors 22 to 25 are fed back as feedback signals.

Further, the controller 26 is configured to supply a drive control signal for the pressure oil pump 16 and to feed back a detection signal from the pressure sensor 16b as a feedback signal.

Although not shown, the controller 26 has an internal reference clock, and is connected to an external computer 28 via an interface 27. The reference clock may be built into the computer.

Reference numeral 29 denotes a feeding mechanism for the wire W, which is formed of a wire wheel 29a, a correction roller/guide roller 29b, a feed roller 29C, etc., and conveys and supplies the wire W onto the stage.

As described above, an example of a multi-slide press using a hydraulic cylinder as a pressurizing source to which the control method of the present invention is applied is constructed. Next, an example of its operation will be described based on the method of the present invention.

The wire W is supplied to a stage (not shown) by a feeding mechanism 29 and cut into a required length.

The cut wire W is clamped and held on the stage by the advancement of the mold 10 that constitutes a part of the clamping means, and is operated according to the operating mode set in advance in the controller 41, for example, according to the stroke time diagram shown in FIG. The molds 6 to 9 of the respective hydraulic cylinders 1 to 4 are processed.

In the method of the present invention, before driving and controlling each of the hydraulic cylinders 1 to 5 according to the command method according to the stroke time diagram, the stroke acceleration during the entire stroke process is formed from the command value for each unit time as appropriate, and the acceleration data is If there is a part where the acceleration suddenly changes or the sign is reversed, the original command value can be changed by inserting a command value indicating zero acceleration in place of the original command value. The aim was to smooth out the stroke motion.

Further, in the present invention, when each hydraulic cylinder 1 to 4 is actually operating according to the above stroke speed diagram, the stroke amount of each cylinder 1 to 4 is detected by the detectors 22 to 2, respectively.
5, and pulse data indicating the stroke amount taken out from each of the detectors 22 to 25 on a predetermined reference clock pulse is sequentially differentiated for each unit time, and the stroke of each of the above-mentioned types 6 to 9 is detected. Form acceleration data during exercise.

On the other hand, during stroke operation, each of the cylinders 1 to 5 is connected to each servo valve via the servo amplifiers 17 to 21 according to a command value preset in the digital controller 26 at a predetermined time or stroke position. 11 to 15 are controlled such as opening/closing or switching, thereby controlling the respective stroke motions.

In the method of the present invention, cylinders 1 to 4 of each hydraulic cylinder are
During the above-mentioned stroke movement, the accelerations are sampled every unit time based on the reference clock to form acceleration data, and the sequentially formed acceleration data are compared with each other to calculate the acceleration data during the stroke movement of each cylinder 1 to 4. The state.

Monitoring is performed using the comparison value of the above acceleration data.

Accordingly, in the present invention, there may be a vibration generating factor such as a point where the acceleration suddenly changes, for example, when the stroke motion changes from an accelerated state to a constant velocity or decelerated state, or vice versa. , when it is detected by the comparison value of the actual acceleration data mentioned above, a command value of zero acceleration is inserted into the control system for an appropriate minute time instead of the command value supplied to the control section.

〔Effect of the invention〕

By inserting a command value of zero acceleration in place of the original command value even for a very short time, the present invention can eliminate vibrations caused by sudden changes in acceleration, etc. The inertia accumulated in the moving member during the stroke movement can be alleviated or eliminated.

As a result, conventionally, high-speed stroke control of hydraulic cylinders has been difficult to perform positioning and speed control of high-speed stroke motions due to vibrations and poor positioning accuracy. According to the method of the present invention, a unique effect can be obtained in that high-speed control can be realized without causing vibration or the like.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a hydraulic cylinder type multi-slide press to which an example of the method of the present invention is applied, and FIG. 2 is a stroke time diagram of each cylinder. 1-5...Hydraulic cylinder, 6-10...Processing mold, 1
1 to 15...Servo valve, 16...Pressure oil pump, 17
~21...Servo amplifier, 22~25...Detector. 26...Digital controller, 29...Feeding mechanism-be L O-r;--

Claims (1)

[Claims] 1. In the drive control of a multi-slide press in which a plurality of dies driven by a plurality of hydraulic cylinders are arranged corresponding to the machining shape of a workpiece, each When the opening and closing of the servo valve is controlled on the same appropriate reference clock, the acceleration of the stroke movement of each cylinder is formed by an appropriate means, and the content of the formed acceleration of the stroke movement of each cylinder is determined by a condition arbitrarily set in advance. A method for controlling a multi-slide press, characterized in that a control command for changing the formed acceleration is given to a drive control section of the servo valve. 2. The multi-slide press control method according to claim 1, wherein the acceleration of the stroke operation of each cylinder is formed from a command value set for each cylinder before driving each cylinder. 3. The method of controlling a multi-slide press according to claim 1, wherein the acceleration of the stroke motion of each cylinder is formed from the stroke motion of each cylinder when it is being driven. 4. The method for controlling a multi-slide press according to claim 2 or 3, wherein the command value for changing the formed acceleration is zero acceleration.