JP2009022993A - Extrusion press, and control method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extrusion press in which a hydraulic pump in an extrusion step, a motor for driving the hydraulic pump and pumps are operated in an efficient state, the number of the operating pumps is reduced, and the energy consumption is small, and a control method of the same. <P>SOLUTION: The extrusion press comprises a control unit capable of providing the priority to the pressure by limiting the discharge rate of a hydraulic pump, and a control unit capable of providing the discharge rate by limiting the pressure of the hydraulic pump. First extrusion is performed with the priority control of the pressure, and the load pressure during the extrusion is detected. Any one of the control units is selected according to the detected pressure to drive the hydraulic pump. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an extrusion press for extruding an aluminum alloy or the like and a method for controlling the extrusion press.

  In general, when extruding materials (billets) made of a metal material such as aluminum or an alloy material thereof are extruded by an extrusion press, a stem is attached to the tip of a main ram driven by a hydraulic cylinder, and a container is placed on the die. In the pressed state, the billet is stored in the container with the stem. Then, the billet is pressed by the stem by further advancing the main ram by driving the hydraulic cylinder. Therefore, the molded product is extruded from the outlet of the die.

  In this conventional extrusion press, high pressure oil is supplied to each hydraulic cylinder of an extrusion press from a plurality of variable displacement hydraulic pumps connected in parallel to operate the extrusion press. For example, the supply of pressure oil to the main cylinder that drives the main ram determines the required oil amount based on the set value set by the operating speed setting device of the stem, and the required oil amount is the variable displacement hydraulic pump 1. If the maximum discharge amount is less than the maximum, the flow rate is controlled so that one variable displacement hydraulic pump is driven to supply the required amount of oil from the same pump, and the remaining variable displacement hydraulic pumps are stopped. Let Also, when the required oil amount is larger than the maximum discharge amount for one or several variable displacement hydraulic pumps, the discharge oil from one or more variable displacement hydraulic pumps driven at or near the maximum discharge state The flow rate is controlled so as to supply the required amount of oil by the discharge oil from one variable displacement hydraulic pump driven in a variable discharge state so as to compensate for the shortage, and the remaining variable displacement hydraulic pumps Stop.

  Further, when the required oil amount changes continuously, the variable displacement hydraulic pump is sequentially driven to continuously supply the required oil amount, and the variable displacement hydraulic pressure driven first at the connecting portion is provided. The next variable displacement hydraulic pump is driven before the pump reaches the maximum discharge amount, and the discharge amount of the variable displacement hydraulic pump driven previously according to the change in the required oil amount and the newly driven variable displacement hydraulic pump The required amount of oil is continuously supplied by variably controlling the discharge amount of the hydraulic pump at the same time. (See Patent Document 1)

By the way, the variable displacement hydraulic pump used in the above-described conventional extrusion press is set so as to obtain a discharge pressure that achieves the maximum press output of the extrusion press with a maximum discharge amount of the pump specification value or a value close thereto. Being controlled. The variable displacement hydraulic pump set in this way cannot be controlled to increase the discharge amount for one variable displacement hydraulic pump even when the load pressure is low. FIG. 6 shows the relationship between the discharge pressure and the discharge amount set by the variable displacement hydraulic pump used in the conventional extrusion press.
And the extrusion speed at the time of product extrusion and the load pressure acting on the main cylinder are rarely used at the maximum value of the extrusion press specification, and are generally used in the range of 70% to 80% of the maximum value. is there. For this reason, the number of variable displacement hydraulic pumps that are driven even though the load pressure is small is uniquely determined by the set extrusion speed.

For example, when an extrusion press composed of three variable displacement hydraulic pumps having the same maximum discharge amount is used and the extrusion speed is set to 75%, three pumps are driven. The first and second pumps are operated at the maximum discharge rate. However, since the third pump is operated at about 25% of the maximum discharge amount, the third variable displacement hydraulic pump and the electric motor that drives the variable displacement hydraulic pump have poor driving efficiency. There was a problem that wasteful power was consumed during the extrusion process.
On the other hand, for example, when an extrusion press composed of four variable displacement hydraulic pumps having the same maximum discharge amount is used and the extrusion speed is set to 75%, the three variable displacement hydraulic pumps have the maximum discharge. Driven by the amount, the fourth variable displacement hydraulic pump is unloaded. However, when the extrusion speed is set to 80%, the fourth variable displacement hydraulic pump is driven at about 20% of the maximum discharge amount, and the fourth variable displacement hydraulic pump and The electric motor that drives the variable displacement hydraulic pump is inefficient at the time of driving and consumes wasted power during the extrusion process.
As described above, in the conventional technology, the variable displacement hydraulic pump and the electric motor that drives the variable displacement hydraulic pump cannot be operated efficiently in a specific extrusion speed setting range of the extrusion press. Was wasting power.
Japanese Patent Publication No. 2-58482

  The present invention has been made to solve this problem, and its purpose is to operate the hydraulic pump and the electric motor that drive the hydraulic pump in the extrusion process and the pump in an efficient state and reduce the number of pumps operated. An object of the present invention is to provide an extrusion press and an extrusion control method that consume less energy.

  In order to achieve the above object, an extrusion press according to claim 1 of the present invention includes a plurality of variable displacement hydraulic pumps connected in parallel to supply hydraulic oil to a hydraulic cylinder of the extrusion press, and a preset operation. In the extrusion press that selectively drives the hydraulic pump by obtaining the required discharge amount of the hydraulic pump based on the speed, the control device of the extrusion press includes a maximum pressure value (Pmax) of the hydraulic circuit and the maximum pressure value (Pmax). ) And the discharge amount (Q1) calculated from the rated load capacity of the electric motor that drives the hydraulic pump is set, and the pressure priority control unit that controls the hydraulic pump, and the maximum discharge amount (Qmax) of the hydraulic circuit A discharge amount priority control unit that sets the maximum discharge amount (Qmax) and a pressure value (P1) calculated from the rated load capacity of the electric motor to control the hydraulic pump; A load pressure detection unit for detecting a large load pressure value (P2), and a calculation unit for calculating a differential pressure between the detected maximum load pressure value (P2) and the pressure value (P1). Extrusion is performed by controlling the discharge amount of the hydraulic pump by the pressure priority control unit, and calculating a differential pressure between the detected maximum load pressure value (P2) and the pressure value (P1), The extrusion selects either the pressure priority control unit or the discharge amount priority control unit based on the calculated differential pressure, and selectively drives the hydraulic pump based on the operating speed of the extrusion press, and the hydraulic pump It is characterized by controlling the required discharge amount.

In the extrusion press control method according to claim 2 of the present invention, a plurality of variable displacement hydraulic pumps are connected in parallel to supply hydraulic oil to a hydraulic cylinder of the extrusion press, and the pump press is controlled based on a preset operating speed. In a control method of an extrusion press that selectively drives the hydraulic pump to obtain a required discharge amount, the maximum set pressure (Pmax) of the hydraulic circuit, the maximum pressure value (Pmax), and the rating of the electric motor that drives the hydraulic pump Pressure priority control for controlling the hydraulic pump by setting the discharge amount (Q1) calculated from the load capacity, the maximum discharge amount (Qmax) of the hydraulic circuit, the maximum discharge amount (Qmax), and the rated load capacity of the motor And the discharge amount priority control for controlling the hydraulic pump with the pressure value (P1) calculated from the above is selectively used, and the first extrusion is performed by the pressure priority control. Control the required amount of discharge, detect the maximum load pressure (P2) during extrusion, and calculate the differential pressure between the detected maximum load pressure (P2) and the pressure value (P1). When the calculated differential pressure is zero (0) or positive, the hydraulic pump discharge amount is controlled by the pressure priority control, and when the calculated differential pressure is negative, the discharge amount priority control is performed. The required discharge amount of the hydraulic pump is controlled.

As described above, in the extrusion press according to the first aspect, the control device calculates the maximum pressure value (Pmax) of the hydraulic circuit, the maximum pressure value (Pmax), and the rated load capacity of the electric motor that drives the hydraulic pump. The pressure priority control unit that controls the hydraulic pump by setting the discharge amount (Q1) obtained in this way, the maximum discharge amount (Qmax) of the hydraulic circuit, the maximum discharge amount (Qmax), and the rated load capacity of the motor A discharge amount priority control unit that controls the hydraulic pump by setting the pressure value (P1) calculated by calculating from the above. Then, the hydraulic pump is selectively driven based on the operating speed setting value of the extrusion press, and the required discharge amount of the hydraulic pump is controlled.
For this reason, it is possible to reduce the number of pumps driven in a specific extrusion speed setting range. Furthermore, the efficiency at the time of driving the hydraulic pump and the electric motor that drives the hydraulic pump is improved, and wasteful power during the extrusion process can be reduced.

  In addition, the load pressure is detected at the time of the first extrusion and the differential pressure from the reference set pressure value is calculated, and the control circuit of the hydraulic pump is selected based on the calculation result. Extrusion with reduced energy can be performed.

In the extrusion press control method according to claim 2, the discharge pressure (Q1) calculated from the maximum set pressure (Pmax) of the hydraulic circuit, the maximum pressure value (Pmax), and the rated load capacity of the electric motor that drives the hydraulic pump. And pressure priority control for controlling the hydraulic pump, the maximum discharge amount (Qmax) of the hydraulic circuit, the maximum discharge amount (Qmax), and the pressure value (P1) calculated from the rated load capacity of the motor. The discharge amount priority control that is set and controls the hydraulic pump is selectively used, and the first extrusion is performed by controlling the discharge amount of the hydraulic pump by the pressure priority control, and the maximum load pressure (P2 at the time of extrusion) ) And the differential pressure between the detected maximum load pressure (P2) and the pressure value (P1) is calculated, and in the second and subsequent extrusions, the calculated differential pressure is zero (0) or positive When said pressure The above control and controls the required discharge amount of the hydraulic pump, the pressure difference was the operation when the negative was possible to control the required discharge amount of the hydraulic pump by the discharge amount priority control.
For this reason, it is possible to reduce the number of pumps driven in a specific extrusion speed setting range. Further, the efficiency at the time of driving the hydraulic pump and the electric motor that drives the hydraulic pump is improved, and wasteful power during the extrusion process can be reduced.

  In addition, the load pressure is detected at the time of the first extrusion and the differential pressure from the reference set pressure value is calculated, and the control circuit of the hydraulic pump is selected based on the calculation result. Extrusion with reduced energy can be performed.

  Embodiments of an extrusion press and an extrusion press control method according to the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of a hydraulic circuit and a control system of an extrusion press according to the embodiment. In the figure, 10A to 10C are variable displacement hydraulic pumps, and 11A to 11C are electric motors for driving the hydraulic pumps. Reference numerals 12A to 12C denote discharge amount control means of the variable displacement hydraulic pump, which controls the tilt angle of the pump by a flow control signal and adjusts the discharge amount. All of the variable displacement hydraulic pumps 10A to 10C are configured with the same specifications. Reference numeral 13 denotes a constant discharge hydraulic pump that supplies a pilot pressure to each device constituting the hydraulic circuit.
14A to 14C are electromagnetic switching valves for switching between unloading and on-loading of each variable displacement hydraulic pump, and 15 is a relief valve for setting the pressure of the hydraulic circuit. An electromagnetic switching valve 16 is arranged to supply pressure oil to the main cylinder 20. Pressure oil is supplied to the side cylinder 21 via the electromagnetic switching valve 17, and the extrusion stem 22 is moved forward and backward.
Reference numeral 18 denotes a pressure detection sensor for detecting a load pressure during extrusion.

  The hydraulic circuit in FIG. 1 is controlled by a control device 31. The control device 31 includes a pressure detector 32 to which the maximum load pressure value (P2) at the time of billet extrusion is input as a detection signal of the pressure detection sensor 18, the detected maximum load pressure (P2), and the pump discharge set pressure (P1). ), A pressure priority control unit 34, a discharge priority control unit 35, a pump control unit 36, and a speed setting unit 37 for setting the operating speed of the extrusion press. Yes. The output signal of the pump control unit 36 is output to each hydraulic device according to the speed set value set in advance in the speed setting unit 37, and the discharge amount of the variable displacement hydraulic pumps 10A to 10C is adjusted. The amount is fed to the extrusion press.

FIG. 2 shows the relationship between the discharge pressure and the discharge amount set by the variable displacement hydraulic pumps 10A to 10C. As shown in the figure, in pressure priority control, the maximum value of pressure and flow rate was calculated from the maximum pressure value (Pmax) of the extrusion circuit and the rated load capacity of the motors 11A to 11C that drive the variable displacement hydraulic pumps 10A to 10C. It is set by the discharge amount (Q1). Further, in the discharge amount priority control, the maximum values of pressure and flow rate are pressure values (P1) obtained by calculating from the maximum discharge amount (Qmax) of the variable displacement hydraulic pumps 10A to 10C and the rated load capacity of the motors 11A to 11C. Is set in
Curves indicated by broken lines indicate the rated power of the motors 11A to 11C that drive the variable displacement hydraulic pumps 10A to 10C, and the discharge amount and the discharge pressure of the variable displacement hydraulic pump in which the maximum load of the motor is the same in any control. It becomes a combination. In the present embodiment, preferable values are P1 × 1.2 = Pmax and Q1 × 1.2 = Qmax.

FIG. 3 shows the relationship between the operating speed of the extrusion press and the pump onload. The on-load and unload timing (selection threshold value) of each variable displacement hydraulic pump in the hydraulic circuit shown in FIG. 1 is as shown in FIG. 3 (a) for pressure priority control and as shown in FIG. 3 (b) for discharge priority control. It is controlled as follows.
As shown in FIG. 3A, the total discharge amount of the three pumps is 100% of the operating speed (three times Q1), and each variable displacement hydraulic pump bears one third. In the pressure priority control, the selection threshold for on-load and unload of the variable displacement hydraulic pump is 33.3% for the second unit and 66,6% for the third unit.
FIG. 3B shows the discharge amount priority control, and the discharge amount of the variable displacement hydraulic pump is set to 120% (Qmax = 1.2 × Q1) of the pressure priority control. Accordingly, in the discharge amount priority control, the on-load and unload selection threshold values of the variable displacement hydraulic pump are 40.0% for the second unit and 80.0% for the third unit. Note that the total discharge amount of the variable displacement hydraulic pump in the discharge amount priority control is the same amount (three times Q1) as in the pressure priority control described above.

FIG. 4 shows the relationship between the control circuit and the pump onload. As shown in the figure, in the pressure priority control, the variable displacement hydraulic pump 10B is on-loaded at a set value of 33.3% operating speed, but in the discharge amount priority control, it is on-loaded at a set value of 40% operating speed. Become. Similarly, the variable displacement hydraulic pump 10C is changed from 66.6% to 80%. For example, when the extrusion speed is set to 75%, the pressure priority control requires three variable displacement hydraulic pumps. Discharge priority control requires only two variable displacement hydraulic pumps.
As described above, in the discharge amount priority control, the discharge amount per variable displacement hydraulic pump is increased, and even if the set value is the same operating speed (for example, in the range of the speed set value from 67% to 79%). The number of variable displacement hydraulic pumps to be driven can be reduced compared to the discharge amount priority control.

Next, a control selection flow will be described with reference to FIG. The operation process of the extrusion press in the present invention is well-known and will not be described in detail.
Prior to the start of extrusion (step 101), various conditions such as the extrusion speed are set in the speed setting unit 37 of the control device 31 in advance. Pressure oil is supplied to the main cylinder 20 and the side cylinder 21, the stem 22 moves forward, the first billet is pressed, and the extruded material is extruded. The extrusion control at this time is performed by pressure priority control (step 102).
The maximum load pressure value (P2) at the time of the first billet extrusion is detected by the pressure sensor 18, and a detection signal is sent to the pressure detector 32 (step 103). While calculating the differential pressure with the preset pressure value (P1) by the calculating part 33, extrusion is continued and the 1st extrusion is complete | finished (step 104).

Subsequently, the second extrusion is started through a known process. In the above-described calculation of the differential pressure, the differential pressure is zero (0) or positive, that is, the detected load pressure value (P2) is the pressure value (P1). When the pressure is equal to or larger than the above, extrusion is performed by controlling the discharge amount of the hydraulic pump by the pressure priority control (step 111), and the operation is repeated N-1 times until the predetermined number of extrusions N is completed. The process ends (step 112).
When the calculated differential pressure is negative, that is, when the detected load pressure value (P2) is smaller than the pressure value (P1), extrusion is performed by controlling the discharge amount of the hydraulic pump by discharge amount priority control (step 121). The extrusion is repeated N-1 times until the extrusion of N extrusions is completed, thereby completing the extrusion (step 122).

  The pump selection threshold when six variable discharge hydraulic pumps are used is as follows. That is, the pump discharge amount per unit in pressure priority control bears 1/6 of the total, the threshold is 16.66% for the second unit, 33.33% for the third unit, and an integer multiple of the number of pumps thereafter And the sixth is 83.3%, and the pump is on-loaded at each threshold. In the discharge amount priority circuit, the pump discharge amount is set to 1.2 times that of the pressure priority circuit, so the threshold value is set as 20% for the second unit, 40% for the third unit, and then set as an integer multiple of the pump. The threshold value is 80%. For this reason, it is possible to secure the necessary amount of oil to be supplied to the main cylinder and the side cylinder without driving the sixth variable discharge hydraulic pump.

  For example, in the past, it was necessary to drive five variable discharge hydraulic pumps in the range of the speed setting value of 67% to 79%, but in the present invention using the extrusion press control by the discharge amount priority circuit, it is 4 in the present invention. Extrusion is possible by driving one hydraulic pump, and two hydraulic pumps can be in an unloaded state. For this reason, it can be set as the extrusion press and extrusion control method with little consumption of energy.

In the embodiment of the present invention, the load pressure in the first extrusion is detected and the second and subsequent extrusion control means is selected to control the pump discharge amount. However, the load pressure during extrusion is clear in advance. In some cases, the circuit configuration may be such that the extrusion is performed by the control means corresponding to the load without detecting the load pressure and calculating the differential pressure between the reference value.
In addition, when performing extrusion with discharge priority control, the motor that drives the variable discharge hydraulic pump is stopped without holding the variable discharge hydraulic hydraulic pump that is not driven in an unloaded state, and a predetermined timing immediately before the completion of the extrusion process It is preferable that means for restarting is provided in the control device.

Further, in place of the control for stopping the electric motor, the electric motor for driving the variable discharge hydraulic pump is provided with a servo motor, and the pump is on-loaded and unloaded by the control means for changing the rotational speed of the electric motor. There may be.
In the embodiment, the configuration using three and six variable discharge hydraulic pumps has been described. However, the number of variable discharge hydraulic pumps to be used is not limited to this, and is configured by a plurality of units including two. May be.

  As described above, there is provided control means that can change the discharge amount of the variable discharge hydraulic pump according to the load condition of the extrusion press without changing the load capacity of the electric motor that drives the variable discharge hydraulic pump. Therefore, the variable discharge type hydraulic pump and the electric motor that drives the hydraulic pump in the extrusion process are operated in an efficient state, and the number of variable discharge type hydraulic pumps is reduced to reduce the consumption of energy. A press control method can be provided.

It is drawing explaining the hydraulic circuit and control system of the extrusion press of this invention. It is drawing explaining the relationship between the discharge pressure and discharge amount of the variable discharge hydraulic pump of this invention. It is explanatory drawing which shows the relationship between the operating speed of the extrusion press of this invention, and a pump on-load threshold value, Fig.3 (a) shows pressure priority control and FIG.3 (b) shows discharge amount priority control. It is drawing explaining the difference of the pump on-load threshold value in the pressure priority control of this invention, and discharge amount priority control. It is a flowchart explaining operation | movement of the extrusion press of this invention. It is drawing explaining the relationship between the discharge pressure and discharge amount of the conventional variable discharge hydraulic pump.

Explanation of symbols

10A to 10C Variable discharge hydraulic pumps 11A to 11C Electric motors 12A to 12C Discharge amount control means 14A to 14C Electromagnetic switching valve 15 Relief valve 18 Pressure detection sensor 20 Main cylinder 21 Side cylinder 31 Controller 32 Pressure detection section 33 Calculation section 34 Pressure priority control unit 35 Discharge amount priority control unit 36 Pump control unit 37 Speed setting unit

Claims (2)

Multiple variable displacement hydraulic pumps are connected in parallel to supply hydraulic oil to the hydraulic cylinders of the extrusion press, and the hydraulic pumps are selectively driven by determining the required discharge amount of the hydraulic pump based on the preset operating speed In the extrusion press
The control device of the extrusion press includes a maximum pressure value (Pmax) of the hydraulic circuit, a discharge amount (Q1) calculated from the maximum pressure value (Pmax) and a rated load capacity of an electric motor that drives the hydraulic pump. A pressure priority control unit configured to control the hydraulic pump;
The maximum discharge amount (Qmax) of the hydraulic circuit, the pressure value (P1) calculated from the maximum discharge amount (Qmax) and the rated load capacity of the electric motor is set, and discharge amount priority for controlling the hydraulic pump is set. A control unit;
A load pressure detector for detecting a maximum load pressure value (P2) during extrusion;
A calculation unit for calculating a differential pressure between the detected maximum load pressure value (P2) and the pressure value (P1),
The first extrusion is performed by controlling the discharge amount of the hydraulic pump by the pressure priority control unit, and the differential pressure between the detected maximum load pressure value (P2) and the pressure value (P1) is calculated,
For the second and subsequent extrusions, select either the pressure priority control unit or the discharge amount priority control unit based on the calculated differential pressure,
An extrusion press characterized by selectively driving the hydraulic pump based on an operating speed of the extrusion press and controlling a required discharge amount of the hydraulic pump. A plurality of variable displacement hydraulic pumps are connected in parallel to supply hydraulic oil to the hydraulic cylinders of the extrusion press, and the hydraulic pumps are selectively driven by determining the required discharge amount of the pump based on a preset operating speed. In the control method of the extrusion press,
Pressure for controlling the hydraulic pump by setting the maximum set pressure (Pmax) of the hydraulic circuit, the maximum pressure value (Pmax) and the discharge amount (Q1) calculated from the rated load capacity of the electric motor that drives the hydraulic pump Priority control,
Select the maximum discharge amount (Qmax) of the hydraulic circuit, the discharge amount priority control that controls the hydraulic pump by setting the maximum discharge amount (Qmax) and the pressure value (P1) calculated from the rated load capacity of the electric motor Use
The first extrusion is performed by controlling the required discharge amount of the hydraulic pump by the pressure priority control, and the maximum load pressure (P2) at the time of extrusion is detected, and the detected maximum load pressure (P2) and the pressure value are detected. Calculate the differential pressure with (P1),
In the second and subsequent extrusions, when the calculated differential pressure is zero (0) or plus, the discharge amount of the hydraulic pump is controlled by the pressure priority control,
When the calculated differential pressure is negative, the required discharge amount of the hydraulic pump is controlled by the discharge amount priority control.

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