JPH0443487B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a press for processing resin materials and the like.

(Prior art) As a press for processing resin plates, the slide is supported by four leveling cylinders provided at the four corners of the bed, and the resin plate is lowered at a constant speed by the main cylinder. There is something that has been processed.

In the above system, when the slide is lowered, the detected value of the position detection device provided in each leveling cylinder is compared with the command value, and the servo of each leveling cylinder is adjusted according to the difference between the detected value and the command value. The valve is controlled to balance the slide within 100 minutes and 5 mm.

(Problems to be Solved by the Invention) However, although the above-mentioned conventional device controls the balance of the slide, it does not control the actual pressure applied to the resin plate, and improvements in this regard are desired. .

That is, pulsations in the cylinder's internal pressure cause pulsations in the balance of the slide, but the conventional control attempts to control the balance only by detecting the position of the slide, and does not take changes in the cylinder internal pressure into account at all. I wasn't there. That is, by controlling only the servo valve based on position detection, it is difficult to correct changes in cylinder internal pressure due to pulsation.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a press that can maintain parallelism with high accuracy, taking into account changes in the internal pressure of the cylinder.

(Means for solving the problems) In order to achieve the above object, the present invention takes the following measures. That is, the present invention is characterized by having a slide that moves up and down with respect to the bed, a main cylinder that lowers the slide, and a plurality of leveling cylinders that are arranged on the bed and support the slide in a balanced manner. In the press, a first control valve interposed in a supply circuit for supplying hydraulic oil to the leveling cylinder, a second control valve interposed in a discharge circuit for discharging hydraulic oil from the leveling cylinder, and a control valve for controlling the main cylinder. a first control device that detects pressure and a support reaction force of the leveling cylinder and controls the first control valve based on these detected values to maintain the internal pressure of the leveling cylinder at a predetermined value; and each of the leveling cylinders. and a second control device that detects the position of the slide and controls the second control valve based on these detected values to maintain the balance of the slide.

(Function) During press working, the slide is lowered by the main cylinder, and each level cylinder supports the slide and is reduced in synchronism to process the workpiece.

During the above-mentioned processing, the first control valve of each leveling cylinder is controlled by the first control device so that the actual pressing force acting on the workpiece is set to a predetermined value, and the second control valve of each leveling cylinder is controlled by the first control device. The slide is balanced under the control of the second control device.

According to the present invention, instead of performing pressure control and position control with one control valve, two control valves are used.
Since the functions are shared between two control valves,
Stable control is possible.

(Embodiment) An embodiment of the present invention will be described below based on the drawings. Figs. 2 and 3 show a hydraulic press for molding SMC resin, where 1 is a bed, 2 is a crown, and 3 is a hydraulic press for molding SMC resin. 4 is a tie rod, 4 is a double-acting main cylinder, 5 is a slide that is raised and lowered by the main cylinder 4, 6 is an upper mold provided on the slide 5,
Reference numeral 7 denotes a lower mold provided in the bed 1, and the resin is processed by these upper and lower molds 6 and 7. Reference numeral 8 denotes double-acting leveling cylinders, which are erected at four corners above the bed 1 and support the slide 5.

Figure 1 shows the control system of the press, where 9 is a hydraulic pump, 10 is a control valve for the main cylinder 4, and 1 is a hydraulic pump.
1 is the pressure in the upper oil chamber of the main cylinder 4, that is,
This is a pressure detector that detects applied pressure.

Reference numeral 12 indicates four electromagnetic servo valves illustrated as first control valves, which control each leveling cylinder 8, and are of a 4-port 3-position switching type.
Each leveling cylinder can be extended and contracted at desired pressures and stopped.

Reference numeral 13 indicates four electromagnetic high-speed ON/OFF valves exemplified as second control valves, which are connected to the lower oil chamber of each leveling cylinder 8. ON/OFF valve 13
is a 2-port 2-position switching valve type, and can be switched at high speed between a position where the lower oil chamber is communicated with the tank side and a position where the communication is cut off,
A minute amount of oil can be drained from the lower oil chamber.

14 is a pressure detector, and each leveling cylinder 8
Detects the lower oil chamber, that is, the support reaction force.

15 is a position detector, and each leveling cylinder 8
By detecting the vertical position of the cylinder rod,
The vertical positions of the four corners of the slide 5 are detected.

Reference numeral 16 denotes a pressure setting device for setting the actual pressure applied to the resin.

17 is a servo amplifier that controls each servo valve 12 to control the actual pressure applied to the resin between the upper and lower molds,
The actual pressure should be within the range set above.

18 is a level comparison circuit, and high-speed ON/OFF valve 1
3 to control the balance of the slide 5.

When the high-speed ON/OFF valve 13 is activated, hydraulic oil is removed from the lower oil chamber of the leveling cylinder 8, but the amount of oil is reduced by the lower oil pressure fluctuation caused by removing the hydraulic oil. The amount of oil is considered to be so small that it does not affect control. That is, the balance level of the slide 5 is controlled by removing a small amount of oil within a pressure change range where the servo valve 12 does not respond. 25 and 26 are relief valves.

Therefore, the pressure detector 11 of the main cylinder 4, the pressure detector 14 of the leveling cylinder 8,
The pressure setting device 16, the servo amplifier 17, and the like constitute a first control device that controls the servo valve 12.

Further, the position detector 15 and the level comparison circuit 1
8 and the like constitute a second control device that controls the high-speed ON/OFF valve 13.

According to the embodiment configured as described above, during resin processing using a press, the slide 5 is lowered by the main cylinder 4, and each leveling cylinder 8 reduces in synchrony while supporting the slide 5. The lower molds 6 and 7 process the resin.

By the way, before resin processing, the actual pressure applied to the resin is set in advance using the pressure setting device 16.

During resin processing, the pressure detector 1
1, the support reaction force of each leveling cylinder 8 detected by the pressure detector 14, the actual pressing force set by the pressure regulator 16, and the other slates 5 and upper mold 6. The pressure to be commanded to each leveling cylinder 8 is calculated from the numerical values that should be taken into consideration such as weight, and this calculation result is given to the servo amplifier 17 as a command value, and the servo amplifier 17 controls the servo valve 12.
Activate. At this time, the pressure in the leveling cylinder 8 is detected by the pressure detector 14 and fed back to the servo amplifier 17 to form a closed loop. In this way, the pressure change in the main cylinder 4 is constantly monitored and compared with the set value, while each leveling cylinder 8 is controlled to keep the actual pressure applied to the resin constant.

Also, during detection machining, each position detector 15
The vertical positions of the piston rods of each leveling cylinder 8 (i.e., the parallelism of the slide 5) detected by the above are constantly compared, and if the difference exceeds a certain value (for example, the difference is 1/100 mm), the high speed of the higher leveling cylinder 8 is By operating the ON/OFF valve 13, a small amount of hydraulic oil is removed from the lower oil chamber of the leveling cylinder 8, and the leveling cylinder 8 is contracted.
The balance of the slide 5 is controlled within a predetermined range.

In the above case, the amount of hydraulic oil removed from the lower oil chamber of the leveling cylinder 8 is reduced by the servo valve 12 due to oil pressure fluctuations caused by removing the hydraulic oil.
Since the amount of oil is so small that it does not affect the control of the servo valve 12, it does not adversely affect the control of the servo valve 12.

Note that the minute amount of oil that does not affect the control of the servo valve 12 is, for example, an oil amount that is about 20% or less of the minimum control oil amount of the servo valve 12.

That is, in the example of a 1000 ton resin molding press, the minimum control oil amount of the servo valve 12 is 1.0 cc/Hz (per operation), and the control oil amount of the second control valve 13 is 0.1.
A minute oil amount of ~0.2cc/Hz was optimal. At this time, it was optimal for the response speed of the second control valve 13 to be controlled at 5 ms (0.005 seconds) while the response speed of the servo valve 12 was 700 ms (0.7 seconds).

Furthermore, if control is performed only with the servo valve 12 as in the past, the parallelism of the slide 5 will be 0.06 mm (60 μm) due to the pulsation of the internal pressure of the cylinder 8, as shown in FIG.
However, when the second control valve 13 of the present invention was used to perform the above control, it was possible to control the pulsation to within ±0.01 mm (10 μm), as shown in FIG.

In addition, in the embodiment, an electromagnetic high-speed valve is used as the second control valve.
Although an ON/OFF valve is used, for example, an electromagnetic servo valve may be used. Furthermore, the present invention can also be applied to a method of pressing materials other than resin.

(Effects of the Invention) As described in detail above, according to the present invention, when performing slide equilibrium control, the actual pressing force acting on the workpiece can be reliably controlled to a predetermined value, so that the slide equilibrium control is improved. It can be done with precision.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is an explanatory diagram of a control system of a press, FIG. 2 is a front explanatory diagram of a press, and FIG. 3 is a sectional view taken along the line A-A in FIG. Fourth
The figure is a graph showing balance control using the press of the present invention, and FIG. 5 is a graph showing balance control using a conventional press. 1...Bed, 4...Main cylinder, 5...
Slide, 8...Leveling cylinder, 11,1
4... Pressure detector, 12, 13... First and second control valves, 15... Position detector, 16... Pressure setting device.

Claims (1)

[Claims] 1. A slide 5 that moves up and down with respect to the bed 1;
a main cylinder 4 that lowers the slide 5;
A press having a plurality of leveling cylinders 8 disposed on the bed 1 and supporting the slide 5 in equilibrium, comprising: a first control valve 12 interposed in a supply circuit that supplies hydraulic oil to the leveling cylinders 8; A second control valve 13 interposed in a discharge circuit that discharges hydraulic oil from the leveling cylinder 8 detects the pressurizing force of the main cylinder 4 and the support reaction force of the leveling cylinder 8, and based on these detected values, the a first control device that controls the first control valve 12 to maintain the internal pressure of the leveling cylinder 8 at a predetermined value; and a first control device that detects the position of each of the leveling cylinders 8 and controls the second control valve 13 based on these detected values. and a second control device that controls and maintains the balance of the slide 5.