JPS5868500A - Load measuring device for press - Google Patents

Abstract

PURPOSE:To know the loading conditions upon dies and the fluctuations of load easily by detecting the pressure in a hydraulic chamber with a pressure sensor, converting the same to a load value, holding the max. value of the load value by a prescribed time and displaying the same digitally. CONSTITUTION:The pressure in a hydraulic chamber is outputted as a voltage with a pressure sensor 3 to an amplifier 4 which supplies a voltage Ph to an adder-subtractor 10. On the other hand, a sample holding circuit is constituted of an analog switch 8, an inversion amplifier 9 and a capacitor C and the pressure Pc in the hydraulic chamber just prior to generation of press load is supplied to the adder-subtractor 10. The outputs of the adder-subtractor 10 are supplied successively to a function generator 12 and a peak holding circuit 13. The max. load value is converted to a digital signal with an A-D converter 14, and the digital signal is stored in a latching circuit 15. The output of the circuit 15 is supplied via a display driving circuit 16 to a display 17 which displays the max. load up to the point of that time digitally.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a press load measuring device equipped with a hydraulic overload safety device.

An example of a conventional hydraulic overload safety device is shown in FIG. This is a hydraulically balanced overload safety device, and cylinder b is attached to the sliding part of the press.
and a seal cup C to form nine hydraulic chambers d, and the pressure in this hydraulic chamber d is controlled by a booster pump e driven by air pressure.
The pressure is maintained at constant pressure. The pressurizing force is transmitted by utilizing the increase in pressure in the hydraulic chamber d as the press load increases, and when the press load exceeds a predetermined value, the cylinder b and seal cup C are The contact portion between the two is separated by causing a relative movement of the two.

The oil in the hydraulic chamber d was leaked to prevent overload. Further, a drop in oil pressure due to oil leakage as described above was detected by a pressure switch f, and when the oil pressure suddenly dropped, the pressure switch f was turned on so that a sudden stop signal was output to the control panel of the press. h is an adjustment screw, and 1 is a tank.

Therefore, although this conventional overload prevention function can prevent overloads, it is not possible to know the press load during normal operation, so it is difficult to know the load changes due to variations in the load of Kinmaro and the supplied material. There was a disagreement that it was not possible to do so.

The present invention provides a pressure sensor for detecting the pressure in a hydraulic chamber that constitutes a part of an overload prevention device, and a means for converting the output of the sensor into a load value.

By adding means for holding the maximum value of the converted load value at a predetermined time and means for numerically displaying the load value held in the skeleton means.

Not only does it have the same overload prevention effect as before, but it also allows you to directly read the press load during normal rolling to protect the gold layer and accurately check load changes due to variations in the supplied material. It is intended to.

The present invention will be explained in detail below based on an embodiment shown in FIGS. 2 to 4.

FIG. 2 shows an electric circuit showing an embodiment of the present invention, in which a constant pressure pump 2 supplies and maintains pressurized oil to a hydraulic chamber 1, which impairs a part of a conventionally known hydraulic overload prevention device.

A pressure sensor 8 to which the pressure of the hydraulic chamber 1 is applied.

Outputs a voltage proportional to the pressure in the hydraulic chamber 1, and this voltage is
After being amplified by the amplifier 4, it is supplied to the addition side input terminal of the adder/subtractor 10. The output of the amplifier 4 is also supplied to an analog switch 80 input.

This analog switch 8 and the 2-inverting amplification 99° capacitor C constitute a sample and hold circuit.

Pressure in hydraulic chamber 1 immediately before press load is generated.

(l) The output voltage ph of the width increaser 114 is sampled and held to obtain a voltage Pc corresponding to the preload of the hydraulic chamber 10. That is, as shown in FIG. 8, the output of the rotary cam switch 6, which is turned ON in the 7'l/s load generation region, is supplied to the transistor 7 via the inverter gate 6, and the transistor 7 (D output t/diode D The analog switch 8 is turned ON only until the crank angle of the press reaches the load generation angle and the rotary cam switch 6 is turned ON. When the rotary cam switch 6 turns on at a different angle, the analog switch 8 turns off.
F and sample the voltage ph output from the amplifier 4 just before this OFF, and the oil pressure is 1! IC) Calculate the voltage Pe to obtain the preload value Ksm.

On the other hand, the preload Ashima voltage Pc obtained by k as above is,
It is supplied to the subtraction side hexagonal terminal of the addition/subtraction @10. still,
0 addition/subtraction 1ii FIOK is variable resistor 11 for gain adjustment
Since the constant "/k" is given, the output of the adder/subtractor IO is #
iPh Pc/K.

Also, the output of the adder/subtractor 10 is the function generated l! n, and a square root operation is performed. That is, the pressure in the hydraulic chamber 1 is Ph,
If the preload of the hydraulic chamber 1 is Pc and the constant is K, then the press load P is.

is given by It should be noted that when the calculated value by 2 and the actual value are compared, they agree to the extent that there is no problem in practical use (9), so it can be said that this is an analog signal corresponding to the output weight of the adder/subtractor 1o.

The analog signal (press load signal) is supplied to the peak hold circuit 13 and held at its peak, #circuit 1
The 30 hold value (maximum load value) is converted into a digital signal by the A-I converter 14 and stored in the latch circuit 15. Incidentally, the reset signal of the peak hold circuit 13 is sent to the gate 1 when the rotary cam switch 5 is ONL.
8 and is supplied to the timing circuit 19 when detected.

The latch circuit 15 is configured to store data using the timing signal output from the timing circuit 19.

Therefore, the peak value held in the peak hold circuit 13 is stored and held in the latch circuit 15 and becomes the tail.
Even if the peak hold circuit 13 attenuates due to changes over time, the maximum value continues to be held.

As mentioned above, the output of the latch circuit 15 that stores the output of the peak hold circuit 13 is supplied to the display 17 via the display driver circuit 16, and the maximum load up to that point is numerically displayed. 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 is supplied as a reference value, and the output of the latch circuit 15 is greatly increased depending on the setting by the setting device 20. A relay is driven via N, and the relay contact is actuated to bring the press to a sudden stop. In addition, the output of the latch circuit 15 is sent to another device 25 as load data.
It has also been made available for use as a data base for metal cover maintenance and monitoring of variations in supplied materials, as well as for load analysis using computers and the like. 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', for example. FIG. 4 is a timing chart of the rotary cam switch 6° reset signal, timing signal, and peak hold circuit output.

As explained above, according to the present invention, the press load is detected from the pressure in the hydraulic chamber that constitutes a part of the overload prevention device, and the maximum load for each cycle is numerically displayed. Since it continues to be held until the specified time, it is possible to immediately check not only the load during normal operation, but also the load when an overload occurs. Therefore, it is possible to easily know the state of the load on the gold INK and load fluctuations due to variations in the supplied materials.

Furthermore, if you have a setting device that compares the numerically displayed load value, you can arbitrarily set the safe value due to overload, so you can set the best load value even if you change the size of the mold or the material. It has the effect of

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main parts of the conventional example, Fig. 2 is an electric circuit diagram of an embodiment of the present invention, Fig. 8 is an operation timing diagram of the rotary cam switch, and Fig. 4 is the rotary cam switch and reset signal. , is a timing chart of the timing signal and peak hold circuit output.

Claims (2)

[Claims] (1) A hydraulic chamber is formed in the slide part, and a KL7'L hydraulic overload safety device is installed to avoid overload by releasing the hydraulic pressure in the hydraulic chamber when the press load exceeds a predetermined value. A pressure sensor detects the pressure in the hydraulic chamber. Means for converting the skeleton sensor O output into a load value. A press load measuring device comprising a means for holding the maximum value of the converted load value at a predetermined period, and a means for numerically displaying the load value held by the mosquito means. (2) A press equipped with a hydraulic overload safety device that forms a hydraulic chamber in the sliding part and releases the hydraulic pressure in the hydraulic chamber when the press load exceeds a predetermined value to avoid overload. , with a pressure sensor that detects the pressure in the hydraulic chamber. means for converting the output of the sensor into a load value; A means for holding the maximum value of the converted load value until a predetermined time, a means for numerically displaying the load value held in the means, and a means for displaying a numerical value of the load value held in the means, and a means for holding the maximum value of the converted load value until a predetermined time, and a means for displaying a numerical value of the load value held in the means, and a means for holding the maximum value of the converted load value until a predetermined time. A press load measuring device comprising means for occasionally outputting a stop signal.