JP6900831B2 - Extrusion speed control method for extrusion press - Google Patents

Description

The present invention relates to an extrusion press and relates to an extrusion speed control method in an extrusion press.

Generally, when a billet made of a metal material such as aluminum or an alloy material thereof is extruded by an extrusion press device, an extrusion stem is attached to the tip of a main ram driven by a hydraulic cylinder, and the container is pressed against a die. Then, store the billet in the container. Then, the billet is pressed by the extrusion stem by further advancing the main ram by driving the hydraulic cylinder. Therefore, the molded product is extruded from the outlet of the die.
After pushing out the billet, the container is retracted slightly by the container cylinder, and the main ram and container are retracted from the position where the discard is out of the container.
Next, the cutting blade of the cutting device is sent between the container and the die, and the billet (called a discard) remaining on the die surface is separated. After that, the main ram is retracted, the extrusion stem is pulled out from the container, the next billet is inserted into the container, and the extrusion molding of the next cycle is started.

Japanese Unexamined Patent Publication No. 2003-048016

In the extrusion stroke of a metal extrusion press, even if the extrusion speed of the set value does not come out due to factors other than the extrusion press machine capacity (die, etc.), the set flow rate is the set value because the hydraulic oil from the variable pump is discharged. The pressure rises to, and a large amount of oil is discharged from the pressure control valve attached to the hydraulic device, and the hydraulic oil temperature in the oil tank rises due to the amount of heat generated by the passing resistance in the pressure control valve, and the operating limit temperature (60 ° C) With the above, the operation is stopped.

Further, as the oil temperature rises, leaks from the hydraulic valve and the like increase, and the required amount of hydraulic oil does not flow to the main ram, and the set speed is not reached.

In the case of increasing the extrusion speed by changing the flow rate of the pump that controls the extrusion speed at the start of the extrusion operation of the extrusion press device.
When the extrusion speed and extrusion pressure are detected and the extrusion pressure reaches the upper limit set value before the extrusion speed reaches the predetermined extrusion speed,
The flow rate of the pump was controlled to be 70% or less of the rated flow rate.

Before controlling the flow rate of the pump to be 70% or less of the rated flow rate, the flow rate of the pump was increased at an rate of increase to the rated flow rate.

In the case of repeating the extrusion operation of the extrusion press device and performing cycle operation.
Measure the time from the start of extrusion operation until the extrusion pressure reaches the upper limit set value,
After the cycle in which the time was measured, the flow rate of the pump was controlled to be 70% or less of the rated flow rate, with the time when the extrusion pressure reached the upper limit set value as a timing.

When controlling the flow rate of the pump to be 70% or less of the rated flow rate, the flow rate of the pump was controlled to be 50% or more of the rated flow rate.

When extruding a product with insufficient extrusion capacity such as a product that is difficult to push, it is necessary to suspend production due to the rise in oil temperature and wait until the oil temperature in the oil tank drops. Because it is possible, continuous operation is possible and the production time can be shortened.

In addition, energy saving operation can be achieved by reducing the discharge amount of the pump.

FIG. 1 is a plan view of an overall overview of the extrusion press of the present invention. FIG. 2 is a cross-sectional view of the variable discharge amount pump. FIG. 3 is a principle diagram of the flow rate of oil of the present invention. FIG. 4 is a principle diagram of the flow rate of oil when the extrusion operation is repeated and the cycle operation is performed in the present invention. FIG. 5 is a flow chart of speed control. FIG. 6 shows the details of the hydraulic circuit of the extrusion press.

An embodiment of the extrusion press discharge amount control method according to the present invention will be described in detail below with reference to the drawings.

The extrusion press used in the present invention is shown in FIG. The end platen 1 and the main cylinder 2 are arranged so as to face each other, and both are connected by a plurality of tie rods 3. A container 5 is arranged on the inner surface of the end platen 1 with a die 4 having an extrusion hole formed therein, and a billet 6 (not shown) is loaded in the container 5 and extruded and pressed toward the die 4. Extruded products with cross sections corresponding to the holes are extruded.

The main cylinder 2 that generates the extrusion force has a built-in main ram 9, which can be pressure-moved toward the container 5. An extruded stem (not shown) is placed concentrically with the billet loading hole of the container 5 at the front end of the main ram 9, and a fixed dummy block (not shown) is brought into close contact with the tip of the extruded stem so as to project toward the container 5 as the main It is attached via the crosshead 8. Therefore, when the main cylinder 2 is driven to advance the main crosshead 8, the extrusion stem is inserted into the billet loading hole of the container 5 and pressurizes the rear end surface of the loaded billet 6 to extrude the extruded product. ..

FIG. 2 shows a cross-sectional view of the variable discharge type piston pump.
FIG. 2 is a side sectional view showing an example of a swash plate type piston pump used in the present invention. The variable discharge amount pump of the extrusion press used in the present invention is not limited to the swash plate type piston pump.

Hereinafter, the variable discharge amount pump used in the present invention will be described with reference to FIG. In the present specification, the pump will be described by the variable discharge amount pump 31.
The pump unit incorporates a pump body 51 that constitutes a variable discharge amount pump. The pump body 51 includes a port plate 55, and if the tilt angle of the swash plate is increased, the stroke of the pump piston 57 in the piston pump body 51 is increased, and the discharge flow rate Q is increased. If the tilt angle is reduced, the stroke of the pump piston 57 is reduced, and the discharge flow rate Q is reduced.
Oil is injected into the piston pump from the inlet 52, passes through the pump piston portion, and exits from the outlet 53.

FIG. 3 shows the extrusion pressure and extrusion speed, the conventional pump discharge amount, and the pump discharge amount of the present invention.
The extrusion pressure is measured by measuring the value of the oil pressure of the main ram and using a pressure transmitter.
A magnet scale (not shown) is attached to the main crosshead 8 to measure the extrusion speed of the extrusion press. The extrusion speed is controlled by issuing a command value to the variable discharge amount pump by arithmetically processing the speed signal obtained from this magnet scale.
The control of the extrusion speed of the extrusion press of the present invention is feedback control.

Conventionally, at the start of the extrusion operation of the extrusion press, when the variable discharge amount pump 31 supplies the hydraulic oil at the rated discharge amount, the pressure of the hydraulic oil reaches the rated pressure and the extrusion speed is set as a target. When the speed was not reached, the hydraulic oil discharged from the variable discharge amount pump 31 returned to the oil tank at the pressure control valve. Since the hydraulic oil passes through the pressure control valve and returns to the oil tank, the oil temperature may rise and the extrusion operation may become difficult.

The start of extrusion operation of the extrusion press means the period from when the pressure of the hydraulic oil reaches the set pressure (for example, 31 MPa) until the flow rate of the hydraulic oil becomes 70% or less of the rated flow rate.

As shown in FIG. 3, when the extrusion speed and the extrusion pressure are detected and the extrusion pressure reaches the upper limit set value before the extrusion speed reaches a predetermined extrusion speed, the hydraulic oil rises to the rated flow rate. The flow rate of the variable discharge amount pump 31 is increased by the rate of increase, and the flow rate of the variable discharge amount pump 31 is controlled to be 70% or less of the rated flow rate when the extrusion pressure reaches the upper limit set value.
The rated flow rate refers to the discharge amount of the variable discharge amount pump 31 required according to the extrusion speed.

As shown in FIG. 3, when the extrusion speed does not reach the set value at the start of the extrusion operation, the variable discharge amount pump 31 discharges a large amount of hydraulic oil by the conventional method. The discharge amount of the variable discharge amount pump 31 is controlled to 70% or less of the rated flow rate according to the actual low-speed extrusion speed.

FIG. 4 shows a case where the extrusion operation is repeated and the cycle operation is performed. The time from the start of the extrusion operation until the extrusion pressure reaches the upper limit set value is measured, and after the cycle in which the time is measured, the variable discharge amount pump 31 is set to the time when the extrusion pressure reaches the upper limit set value. It was decided to control the flow rate of the above to 70% or less of the rated flow rate.

Further, in the present invention, when the flow rate of the variable discharge amount pump is controlled to be 70% or less of the rated flow rate, the flow rate of the variable discharge amount pump is controlled to be 50% or more of the rated flow rate. To.

When extruding a billet with an extrusion press, the extrusion speed is predetermined if the billet diameter and extrusion ratio are determined. Further, the tilt angle of the variable discharge amount pump 31 is also determined.
However, because the billet temperature is lower than the set value, the die temperature is low, the container temperature is lowered, etc., the target extrusion speed cannot be obtained with the command value to the normal variable discharge amount pump 31. There is.

As described above, if the variable discharge pump 31 supplies the rated discharge amount of hydraulic oil, but the extrusion speed does not reach the set speed, excess hydraulic oil will flow from the pressure control valve to the oil tank. Return.
The conventional pump flow rate is a discharge amount calculated from a target extrusion speed.

Normally, when it is desired to obtain a predetermined extrusion speed, it can be realized by changing the tilt angle of the variable discharge amount pump 31 according to the extrusion speed. That is, there is a one-to-one relationship between the extrusion speed and the tilt angle, in other words, the extrusion speed and the discharge amount of the variable discharge amount pump.

According to the present invention, the amount of excess hydraulic oil generated at the start of extrusion operation at the extrusion speed set before the start of extrusion is adjusted to the tilt angle of the variable discharge amount pump 31 corresponding to the extrusion speed during operation at the initial stage. The discharge amount of the variable discharge amount pump 31 is set to 70% or less.

To reduce excess hydraulic oil, change the command value of the variable discharge amount pump 31 from the actual extrusion speed to reduce the tilt angle of the variable discharge amount pump 31 and discharge the variable discharge amount pump. Is to reduce.

FIG. 5 shows a flowchart of the control of the present invention. When the extrusion pressure is rated (31 MPa), the variable discharge amount pump 31 is adjusted by the amount of hydraulic oil returning from the first pressure control valve 35 and the second pressure valve 36 to the oil tank 37 so that the actual extrusion speed does not decrease. It is a control that lowers the discharge amount of.

FIG. 6 shows a hydraulic circuit diagram of the extrusion press.
The hydraulic oil discharged from the first variable discharge amount pump 31 and the second variable discharge amount pump 33 is
It reaches the main cylinder 2 and the side cylinder 10 through the pipeline 38 and the pipeline 39.
Further, the extrusion pressure of the hydraulic oil of the main cylinder 2 for producing the push output is set by the first pressure control valve 35 and the second pressure valve 36, and the set value does not change during extrusion.
Further, in the conventional initial stage, the hydraulic oil returns from the pressure control valve to the oil tank because the hydraulic oil flows from the pressure control valve 35 toward the oil tank 37.

Since the present invention has the above configuration, the following effects can be obtained.
When extruding a product with insufficient extrusion capacity such as a product that is difficult to push, it is necessary to suspend production due to the rise in oil temperature and wait until the oil temperature in the oil tank drops. Because it is possible, continuous operation is possible and the production time can be shortened.

In addition, energy saving operation can be achieved by reducing the discharge amount of the pump.

1 End platen 2 Main cylinder 3 Tie rod 4 Die 5 Container 6 Billet 7 Extrusion stem 8 Main crosshead 9 Main ram 10 Side cylinder 31 Variable discharge pump 32 Motor 35 First pressure control valve 36 Second pressure control valve 37 Oil Tank 51 Piston Pump Machine 52 Inlet 53 Outlet 55 Port Plate 57 Pump Piston

Claims (2)

In the case where the extrusion operation start of the extrusion press device, Ru increases the extrusion rate by changing the flow rate of the pump to control the extrusion speed,
In the first cycle, by detecting the extrusion speed and extrusion pressure, before the extrusion rate reaches a predetermined extrusion rate, when the extrusion pressure reaches the upper limit set value, the upper limit setting the extrusion pressure from the start extrusion operation Measure the time to reach the value and
The said cycle after measured the said time, leaving press as the timing time the extrusion pressure reaches the upper limit set value, the flow rate of the pump was and controls to be less than 70% than the rated flow rate Speed control method. Flow rate of the pump, in case of controlling to be less than 70% of the rated flow, the flow rate of the pump, to claim 1, characterized in that controlled to be 50% or more of the rated flow The extrusion speed control method described.

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