JPS646880B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an automatic die height adjustment device for a press. To set the die height using the slide adjustment device installed on the press, it is necessary to apply a preload between the upper and lower molds. For this reason, various automatic die height adjustment devices have been proposed and put into practical use, but none of them can be said to be sufficient. In view of these circumstances, the present invention detects the pressure in the hydraulic chamber of the slide that constitutes a part of the overload safety device or load meter of the press, and converts the load value from this pressure to any preset arbitrary setting. To provide an automatic die height adjustment device that automatically stops a slide adjustment motor when a preload value is reached to give a desired preload, thereby setting the die height with high precision. The present invention will be explained in detail below based on an illustrated embodiment. FIG. 1 is an electric circuit diagram showing an embodiment of the present invention, in which a hydraulic chamber 1 constituting a part of a hydraulic overload prevention device is formed in a sliding part of a press, and a constant pressure pump is provided in this hydraulic chamber 1. 2, pressure oil at a predetermined pressure is supplied. The pressure sensor 3 to which the pressure of the hydraulic chamber 1 is applied is
A voltage proportional to the pressure in the hydraulic chamber 1 is output, and this voltage is amplified by an amplifier 4 and then supplied to an addition side input terminal of an adder/subtractor 10. In addition, the amplifier 4
The output of is also supplied as the input of analog switch 8. This analog switch 8 and inverting amplifier 9,
Capacitor C constitutes a sample and hold circuit,
The pressure in the hydraulic chamber 1 immediately before the press load is generated, that is, the output voltage Ph of the amplifier 4 is sampled and held to obtain the voltage Pc corresponding to the prepressure in the hydraulic chamber 1. That is, as shown in FIG. 2, the output of the rotary cam switch 5, which is turned ON in the press load generation region, is supplied to the transistor 7 via the inverter gate 6, and the output of this transistor 7 is supplied to the analog switch 8 via the diode D. By supplying it as a control input, the analog switch 8 is activated only until the press crank angle reaches the load generation angle and the rotary cam switch 5 is turned on.
Turn it on. When the load generation angle is reached and the rotary cam switch 5 is turned ON, the analog switch 8 is turned OFF and the voltage Ph output from the amplifier 4 immediately before this OFF is sampled and corresponds to the preload value of the hydraulic chamber 1. I am trying to obtain the voltage Pc that On the other hand, the preload equivalent voltage obtained as above
Pc is supplied to the subtraction side input terminal of the adder/subtractor 10. Incidentally, since the constant 1/K is given to this adder/subtractor 10 by the variable resistor 11 for gain adjustment, the output of the adder/subtractor 10 becomes Ph-Pc/K. Further, the output of the adder/subtractor 10 is supplied to a function generator 12 to perform a square root calculation. That is, hydraulic chamber 1
When the pressure of is Ph, the preload of hydraulic chamber 1 is Pc, and the constant is K, the press load P is: is given by When the calculated value using this formula was compared with the actual value, it was found that they matched to the extent that there was no practical problem, so the output Ph- of the adder/subtractor 10
The value obtained by square rooting Pc/K using the function generator 12, that is,
Output of function generator 12

[Formula] can be said to be an analog signal corresponding to the press load. The analog signal (press load signal) is supplied to the peak hold circuit 13 and held at its peak, and the hold value (maximum load value) of the circuit 13 is converted into a digital signal by the A-D converter 14 and then sent to the latch circuit 15. is memorized. The reset signal for the peak hold circuit 13 is supplied when the timing circuit 19 detects through the gate 18 that the rotary cam switch 5 is turned on, and the latch circuit 15 receives the timing signal output from the timing circuit 19. I try to remember it. Therefore, since the peak value held in the peak hold circuit 13 is stored and held in the latch circuit 15, the maximum value continues to be held even if the peak hold circuit 13 attenuates due to changes over time. The output of the latch circuit 15 which stores the output of the peak hold circuit 13 as described above is supplied to the display 17 via the display driver circuit 16 to numerically display the maximum load up to that point. At the same time, the output of the latch circuit 15 is also supplied to a comparator 21 to which the output of the digital setting device 20 is supplied as a reference value. A relay 23 is driven through the relay 23, and a relay contact 24 is actuated to abruptly stop a slide adjustment motor (not shown), thereby preventing the slide from descending. The output of the latch circuit 15 is also supplied to other devices 25 as load data, so that it can be used as data for mold protection and monitoring of variations in supplied materials, as well as data for load analysis using a computer or the like. It's summery.
Although the latch circuit 15 is reset when the timing signal is supplied in the next cycle, it may be reset when the crank angle reaches 30 degrees, for example. Furthermore, the comparator 21 is
In principle, it acts only on die height adjustment, but since the power to the slide adjustment motor is turned off when the die height is not being adjusted, no particular inconvenience will occur even if it is operated all the time. In the above configuration, when adjusting the die height, the slide adjustment motor is activated to lower the slide after the mold is carried into the press as in the conventional method. The slide comes into contact with the upper die as it descends, but the slide continues to descend thereafter. Then, the load increases and the pressure in the hydraulic chamber 1 rises, so the load displayed on the indicator 17 gradually increases. and,
When this load reaches the set value of the digital setting device 20, the output of the comparator 21 turns ON and the relay 23 is driven via the relay driver 22, so a stop signal is supplied to the slide adjustment motor and the slide stops. . Further, after the slide has stopped in this manner, the upper mold is clamped, and then the slide is returned to the top dead center to complete the die height adjustment. The slide adjustment device, for example, as shown in FIG. 3, includes a slide adjustment motor 26, a worm 27 driven by the motor 26, and an adjusting screw 29 screwed into a connecting rod 28, which rotate integrally. The adjustment screw 29 can be configured to expand and contract relative to the connecting rod 28 by the rotation of the slide adjustment motor 26. 31 is a crankshaft, and 32 is a slide. As described above, according to the present invention, the slide adjustment device operates to lower the slide and apply preload until it reaches an arbitrary load value set by a digital setting device, etc., so that the die height can be automatically adjusted. Furthermore, since the preload value can be changed arbitrarily, it is possible to easily obtain the optimum die height according to the mechanical properties of the material to be processed, the characteristics of the mold, etc.

[Brief explanation of the drawing]

Fig. 1 is an electrical circuit diagram of an embodiment of the present invention;
The figure shows the operation timing diagram of a rotary cam switch.
FIG. 3 is a sectional view of the slide adjustment device. 1... Hydraulic chamber, 3... Pressure sensor, 15... Latch circuit, 20... Digital setting device, 21...
comparator. 22...Relay driver, 23...
...Relay, 24...Relay contact, 26...Slide adjustment motor,

Claims (1)

[Claims] 1. In a die height adjustment device that applies a preload between the upper and lower dies attached to a press machine, there is a setting device that presets an arbitrary load value as a set value, and a hydraulic chamber provided in the sliding part of the press machine. a pressure sensor that detects pressure at least during die height adjustment; a means for electrically comparing the output of the sensor with the set value; and when the comparing means detects that the output of the sensor has reached the set value. and means for outputting a signal to stop a slide adjustment motor.