SU1447697A1 - System for controlling hydraulic press - Google Patents

Abstract

The invention relates to the field of mechanical engineering, namely to control systems of hydraulic presses. The goal is to expand the technological capabilities and improve the quality of the extruded products by ensuring a smooth decrease in pressure in the master cylinder. The control system contains high and low pressure pumps connected through distribution equipment to the main and return cylinders to automatically maintain the rate of pressure reduction in the main cylinder. An adjustable choke, a safety valve and a flow controller with an electronic control unit are installed in parallel at the outlet of the drain valve. On the line between the piston cavity of the servo drive drain valve and its distributor is a reducing valve. The control system allows the pressure in the master cylinder to decrease smoothly and over a wide range in time. 1 il. Yu

Description

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The invention relates to mechanical engineering, namely to hydraulic presses.

The purpose of the invention is to expand the technological capabilities and improve the quality of the pressed products by ensuring a smooth decrease in pressure in the master cylinder.

The drawing is a schematic diagram of the control system.

The control system of the press 1 comprises a high-pressure pump 2 and a low-pressure pump 3 connected by pressure lines 4 and 5 through distribution equipment to the main 6 and return 7 cylinders. Safety lines 8 and 9 are installed on mains x 4 and 5, the drainage of which is applied to tank 10. Distribution equipment includes a valve II of the main and return cylinders, a valve 12 of the multiplier 13 and a valve 14 of the control of the piston cavity 15 of the servo 16 of the drain valve 17, the cavities 18 of the high pressure of the multiplier 13 through the valves 19 and the hydraulic lock 20 are connected to the cavity of the main cylinder 6. Highway 21. In the main section between the cavity 15 and the distributor. 14, a reduction valve 22 is installed. The outlet of the valve 17 and the rod cavity of the servo drive 16 are connected to a drain line 23, on which an adjustable 24, a safety valve 25 and a flow controller 26 are installed with an electronic control unit 27 connected to an automatic control device including a pressure converter 28 The software program 29 and the press control unit 30 are programmed. An electrocontact pressure gauge 31 is installed on the cylinder line, the position of the movable crosshead is controlled by end switches 32 and 33, and the servo drive 34 cavity of the hydraulic lock 20 is connected to the cylinder cavities 7.

The control system works as follows.

At start-up, the distributor .11 is turned on, which connects the pump lines 4 and 5 through the hydraulic lock 20 to the main cylinder 6. The movable traverse 35 of the press rises, and the liquid displaced from the return cylinders 7 enters the tank 10. After closing molds (not shown, as the pressure in the cylinder 6 increases, the preload valve 9 of the low pressure pump 3 is turned off. And a further pressure increase in the cylinder 6 is generated from the high pressure pump 2. During operation, the pressure transducer 2 8 generates a continuous electrical signal to the program-master device 29, which transmits the signal to the press control unit 30.

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When pressure in the cylinder 6 is adjusted, the safety valve 8 switches the valve 12, which connects the pump line 4 alternately with the control cavities of the multiplier 13 and, at the same time, high pressure cavities 18 are pumped through the valves 19 to the cavity of the cylinder 6. After the pressure rises the cylinder 6 to the required value, the block 30 gives a command for holding, while the pumps 2 and 3 and the distributor 12 are turned off.

At the end of the shutter speed, the valve, the soy 3 and the distributor 14 connect the main pipe 5 of the pump 3 through the reducing valve 22 with the piston capacity 15 of the servo 16 are turned on. The drain valve 17 opens and the liquid of the cylinder 6 enters through the main 21 through the valve 17 the rod cavity of the servo 16 and through the flow controller 26 and the choke 24 goes to the drain through the line 23.

When the pressure decreases, the device 29 outputs a signal to the control unit 27 of the flow control valve 26, which controls the rate of flow of fluid from the rod cavity of the servo drive 16 to the drain. In case of an overpressure rate, the signal from pressure transducer 28 in device 29 is compared with a program and converted into an error signal, which enters flow regulator unit 27, resulting in an increase in pressure in the rod cavity of servo drive 16, and valve 17 partially overlaps the drain {liquid from cylinder 6.

To eliminate possible auto-oscillations of the servo 16, throttle grooves (not shown) are provided on the valve 17.

In the event of an emergency pressure increase in the servo drive 16, the liquid from the cavity of the main cylinder 6 is bypassed to drain through the safety valve 25, which is set to a response pressure slightly greater than the pressure on the safety valve.

In the event of a decrease in the pressure relief rate, the device 29 issues a signal to increase the flow area of the flow regulator 26, which leads to the opening of the valve 17, as a result of which the pressure relief rate from the cylinder 6 increases.

At the end of pressure relief, the bottom contact of the electrocontact gauge 31 closes, the control unit 30 shuts off the valve 14 and turns on the valve 11, which connects lines 4 and 5 to the return cylinders 7 and the servo actuator of the hydraulic lock 20. The check valve of the hydraulic lock 20 opens, connecting line 21 of the master cylinder 6 through the distributor 11 with the tank 10. The mobile yoke 35 is lowered.

the liquid from the master cylinder 6 through the open hydraulic lock 20 is discharged into the tank 10. At the end of the return stroke, the limit switch 32 is pressed, which gives a signal to shut off the distributor ii and pumps 2 and 3. The economic effect of the introduction is achieved by expanding technological capabilities and increasing quality products.

Claims (1)

Invention Formula servo-drive servo through a distributor with a pressure line of pumps, as well as an automatic control device, characterized in that, in order to expand the technological capabilities and improve the quality of the pressed products by ensuring a smooth decrease in pressure in the main cylinder, it is equipped with a flow controller with an electronic control unit , safety valve, adjustable throttle and pressure reducing valve, with adjustable throttle, safety valve and flow controller installed steam their alleles are connected with their inlets to the outlet of the drain valve and the hydraulic press control system, which contains high and low pressure pumps connected by pressure lines through the distribution equipment to the main and return cylinders; on the section of the line between the piston cavity of the servo drive of the drain valve and its distributor, and the electronic unit of the flow control valve is connected with the rod cavity of the servo-electrically connected stvom for auto- and the drain line, and the piston po- mathic control. mi, hydraulic lock, drain valve with hydraulic servo, connected by its entrance to the cavity of the main cylinder, you servo-drive servo through a distributor with a pressure line of pumps, as well as an automatic control device, characterized in that, in order to expand the technological capabilities and improve the quality of the pressed products by ensuring a smooth decrease in pressure in the main cylinder, it is equipped with a flow controller with an electronic control unit , safety valve, adjustable throttle and pressure reducing valve, with adjustable throttle, safety valve and flow controller installed steam their alleles are connected to the outlet of the drain valve and the outlets — to the drain line; a reduction valve is installed on the section of the line between the piston cavity of the drain valve servo actuator and its distributor, and the electronic control unit of the flow regulator is electrically connected with the device for automatic management yes WS--