JPH06106592A - Method and apparatus for controlling molding machine - Google Patents

Abstract

PURPOSE:To designate, alter over-ride characteristics without altering a hydraulic circuit by so controlling a charging mechanism that resin is charged at a charging speed having a predetermined correlation with respect to a measured load pressure. CONSTITUTION:An injection screw 12 is driven by a hydraulic pump 14 disposed in a heating cylinder to inject, charge resin of molten state in the cylinder in a mold, and a pressure sensor 16 measures a hydraulic pressure for driving the screw 12 to be regarded as being a load pressure of an injection molding machine. A microprocessor 20 having functions of calculating means and control means stores the measured pressure of the sensor 16 in a RAM 24, obtains a charging speed of the screw 12 having a predetermined correlation with respect to a hydraulic value based on the hydraulic value by using the calculating function, and so controls the pump 14 as to charge the resin in the mold at the obtained charging speed, thereby setting over-ride characteristics to a desired pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding machine control method and control apparatus, and more particularly to a molding machine control method and control apparatus for controlling a resin filling speed in the molding machine.

[0002]

2. Description of the Related Art For example, in an injection molding machine, depending on the shape of a molded product, a load pressure of the molding machine (eg, hydraulic pressure of a hydraulic actuator for driving a resin filling mechanism) and a resin molding die It is necessary to change the relationship with the filling speed, that is, the pressure-speed characteristic (hereinafter referred to as the override characteristic). For example, when molding a thick molded product such as a lens, low-speed injection is required, and in the resin filling process, filling is performed at a constant filling speed, and the filling speed is rapidly increased immediately before the load pressure reaches its maximum. You need to drop it. Such an override characteristic is called a high override characteristic. On the other hand, when molding a thin molded product such as a relay case, high-speed injection is required, and it is necessary to initially perform high-speed filling in the resin filling process, and gradually reduce the filling speed as the load pressure increases. . Such an override characteristic is called a low override characteristic. Conventionally, in order to change the override characteristic of the molding machine, the desired override characteristic has been obtained by changing the hydraulic circuit of the hydraulic actuator for driving the resin filling mechanism.

[0003]

However, the above-mentioned conventional method of changing the override characteristic of the molding machine has the following problems. Since the override characteristic is determined by the hydraulic circuit of the hydraulic actuator for driving the resin filling mechanism, it is necessary to change the hydraulic circuit when changing it. However, since the operation of the molding machine must be stopped while the work of changing the hydraulic circuit is performed, there is a problem that economic loss is large. Further, changing the hydraulic circuit is a troublesome work, and in addition, there is a problem that adjustment is difficult to obtain a high-quality molded product. Therefore, it is an object of the present invention to provide a control method and a control device for a molding machine capable of designating and changing the override characteristic without changing the hydraulic circuit.

[0004]

In order to solve the above problems, the present invention has the following constitution. That is, the control method measures the load pressure of the molding machine, and controls the filling mechanism so as to fill the resin into the molding die at a filling speed that has a predetermined correlation with the measured load pressure. It is characterized by More specifically, the filling speed may be calculated based on the measured load pressure according to a predetermined arithmetic expression having the correlation, or the filling speed may be obtained. May be obtained by searching a data table of the filling speed with respect to the load pressure, which is predetermined and has the above-mentioned correlation based on the measured load pressure. On the other hand, the control device includes a measuring unit for measuring the load pressure of the molding machine, a storage unit for storing the load pressure measured by the measuring unit, and the load pressure stored in the storage unit. And a control means for determining a filling speed having a predetermined correlation with the load pressure and controlling the filling mechanism so as to fill the resin into the molding die at the calculated filling speed. It is characterized by doing. Further, in this control device, a calculation means for calculating the filling speed is provided, and the control means is predetermined so as to have the correlation based on the load pressure stored in the storage means. The filling speed may be calculated according to an arithmetic expression, or a data table of the filling speed with respect to the load pressure having the correlation may be stored in advance in the storage means, and the control means may The filling speed may be obtained by searching the data table based on the load pressure stored in the storage means.

[0005]

[Operation] The operation will be described. In the control method,
The filling mechanism is controlled so that the resin is filled into the mold at a filling speed that has a predetermined correlation with the measured load pressure, so when changing the override characteristics, simply change the correlation. Thus, it becomes possible to obtain a desired override characteristic. On the other hand, in the control device, based on the load pressure stored in the storage means, the control means obtains a filling speed having a predetermined correlation with the load pressure, and at the obtained filling speed. Since the filling mechanism is controlled so as to fill the molding die with the resin, it is possible to obtain a desired override characteristic only by changing the correlation given to the control means.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. In the present embodiment, a control device of an injection molding machine suitable for carrying out the control method of the present invention will be described as an example. In the block diagram of FIG. 1, an injection screw 12 is driven by a hydraulic pump (hydraulic actuator) 14. Injection screw 12
Is disposed in a heating cylinder (not shown), and when driven by the hydraulic pump 14, the resin in a molten state in the heating cylinder is injected and filled into a molding die (not shown). The hydraulic pump 14 is provided with an electronic control unit including a flow control valve (not shown), and the control unit actuates the flow control valve in response to an input control signal to control the hydraulic pressure of the hydraulic pump 14. A filling mechanism is configured so that the injection screw 12, the hydraulic pump 14 and the like fill the molding die with resin. In this embodiment, the advancing speed of the injection screw 12 is regarded as the filling speed of the resin into the molding die, and the advancing speed can be measured via a sensor (not shown).

Reference numeral 16 is a pressure sensor which is an example of a measuring means, and measures the hydraulic pressure for driving the injection screw 12, which is regarded as the load pressure of the injection molding machine. The load pressure may be the resin pressure in the heating cylinder or the resin pressure in the molding die, in addition to the hydraulic pressure of this embodiment. Further, when the injection screw 12 is driven by an electric motor, for example, the load of the motor may be obtained from the motor current, and the load pressure may be obtained by calculation or a data table search based on the load. Reference numeral 18 is a keyboard which is an example of input means,
It is possible to input the control parameters necessary for the arithmetic expression for obtaining the filling speed of the resin having a predetermined correlation. The control parameters include, for example, the maximum value of the load pressure, the range of the load pressure that changes the speed, and the maximum value of the filling speed. In addition, control data, control commands and the like necessary for controlling the injection molding machine can be input from the keyboard 18. As the input means, in addition to the keyboard 18, an input means operated by an operator such as a touch panel, an external memory such as an IC card, or online can be used.

Reference numeral 20 denotes a microprocessor (MPU) having the functions of a calculation means and a control means. The calculation means calculates the filling speed of the injection screw 12 according to a predetermined calculation formula. Further, as the control means, the oil pressure measured by the pressure sensor 16 is stored in the memory means described later, and the filling speed of the injection screw 12 having a predetermined correlation with the oil pressure value is stored based on the oil pressure value. Is calculated using the calculation function, and the hydraulic pump 14 is controlled to fill the resin into the molding die at the calculated filling speed to set the override characteristic to a desired pattern.
Note that the MPU 20 does not calculate the filling speed of the injection screw 12 but stores a data table of the filling speed with respect to the load pressure having the above-mentioned correlation in advance in the storage means described later, and the hydraulic pressure measured by the pressure sensor 16 is stored. The data table is searched based on the value and the injection screw 12
You may make it calculate | require the filling speed of. Others, MPU
Reference numeral 20 measures the forward speed (filling speed) of the injection screw 12 and controls each part of the injection molding machine according to the control program.

Reference numeral 22 is a color CRT display.
The display 22 displays control parameters, commands, operating conditions of the injection molding machine, M
Information processed by the PU 20 and the like can be displayed. Two
Reference numeral 4 denotes a RAM which is an example of a storage unit, and the pressure sensor 1
The pressure value measured by 6 is stored. Also MPU20
Does not calculate the filling speed of the injection screw 12 by calculation, but searches a data table of the filling speed with respect to the load pressure having a predetermined correlation to search the injection screw 12
When calculating the filling speed of, the data table of the filling speed with respect to the load pressure having the correlation is stored in the RAM 24 in advance. The RAM 24 temporarily stores various data input to the MPU 20 via the keyboard 18, information processed by the MPU 20, calculation results, and the like. In addition,
In addition to the RAM 24, an external memory such as an IC card can be used as the storage means. In particular, when the data table is stored, it can be rewritten by using an external memory, and the data can be easily updated. Reference numeral 26 is a ROM in which an operating system of the MPU 20, a control program for setting the override characteristic into a desired pattern, control data, and the like are stored in advance. An external memory such as an IC card may be used for the control program and control data.

Next, an example of calculation control of the override characteristic will be described with reference to FIG. The graph of FIG. 2 shows one model of override characteristics. In FIG. 2, PS: load pressure (hydraulic pressure value measured by the pressure sensor 16)
, QS: maximum value of filling speed (advancing speed of the injection screw 12), PV: range of changing the filling speed with respect to the load pressure, Pt: load pressure value for changing the override characteristic, Pa: on the graph Load pressure value at arbitrary point P, Qa: Filling speed at point P to be obtained. Note that PS, QS, and PV are input to the MPU 20 from the keyboard 18 or are set in advance, and P
The pressure sensor 16 measures a and is input to the MPU 20. Of course, these values are stored in the RAM 24 and MP
U20 reads it for calculation. First, Pt is calculated by the following equation.

[0011]

[Formula 1]

Further, the constant C used for the calculation is defined by the following equation.

[0013]

[Formula 2]

In the graph of FIG. 2, since the override characteristic changes before and after the load pressure Pt, the coefficient K is defined as follows.

[0015]

[Formula 3]

[0016]

[Formula 4]

When Pt, C, and K are obtained by the above calculation, the filling speed Qa at the point P to be obtained is obtained by the following equation.

[0018]

[Formula 5]

The filling speed Qa obtained by this calculation
The MPU 20 sends a control signal to the control unit of the hydraulic pump 14 so that the injection screw 12 moves forward. By repeating this operation continuously, the override characteristic can be set to a desired pattern. The arithmetic expression for determining the override characteristic is not limited to the above arithmetic expression. That is, a desired override characteristic can be arbitrarily realized by using an arithmetic expression that determines the filling speed with respect to the load pressure value in accordance with various molding conditions such as the shape of the molded product and the structure of the molding die.

When a load pressure-filling speed data table is created in the RAM 24 regardless of the arithmetic expression, the filling speed for the load pressure is obtained in advance by the above-mentioned arithmetic expression, and the external memory or The data is stored in the ROM 26 as data, and the MPU 20 reads it from the external memory or the ROM 26 during control and creates a table in the RAM 24. In case of data table method, MPU20
Reads out the filling speed Qa corresponding to the load pressure measured via the pressure sensor 16 from the table of the RAM 24 and MP so that the injection screw 12 advances at the filling speed Qa.
U20 sends a control signal to the control unit of the hydraulic pump 14. By repeating this operation continuously, the override characteristic can be set to a desired pattern.

Examples of override characteristics are shown in FIGS. FIG. 3 shows the load pressure on the horizontal axis and the filling speed on the vertical axis (the same applies to FIGS. 4 and 5). This graph shows a low override characteristic without a sudden change. This example is an override characteristic suitable for molding thin molded products such as relay cases and cups. FIG. 4 shows a high override characteristic, in which the characteristic changes rapidly from the point R. This example is an override characteristic suitable for molding thick molded products such as lenses. FIG. 5 shows the intermediate override characteristic between FIGS. 3 and 4, and the change from the point S shows the intermediate characteristic between FIG. 3 and FIG. This example is an override characteristic suitable for molding a medium-thickness molded product. In addition, as described above, the override characteristic can be set to any desired value by changing the arithmetic expression. For example, a plurality of patterns of override characteristics (for example, low override characteristic and high override characteristic) can be included in a series of override characteristics. It is also possible to have a characteristic) that has both characteristics. In other words, the filling speed should be correlated with the load pressure. Although various preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. For example, a molding machine is not limited to an injection molding machine, and a compression molding machine or an injection compression machine is used. Needless to say, many modifications can be made without departing from the spirit of the invention, such as the use in a molding machine, a transfer molding machine, or the like.

[0022]

In the method of controlling the molding machine according to the present invention, the filling mechanism is controlled so that the resin is filled into the molding die at a filling speed that has a predetermined correlation with the measured load pressure. Therefore, when changing the override characteristic, it is possible to easily obtain the desired override characteristic only by changing the correlation. On the other hand, in the control device, based on the load pressure stored in the storage means, the control means obtains a filling speed having a predetermined correlation with the load pressure, and at the obtained filling speed. Since the filling mechanism is controlled so as to fill the molding die with the resin, desired override characteristics can be easily obtained only by changing the correlation given to the control means. Therefore, even if it is necessary to change the override characteristics by changing the molded product or molding die, it is only necessary to change the correlation, and there is no need to change or adjust mechanical parts such as the hydraulic circuit. As a result, the molding machine can be stopped for a short time, which is a remarkable effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a control device for a molding machine according to the present invention.

FIG. 2 is a graph showing an example of override characteristics.

FIG. 3 is a graph showing an example of another override characteristic.

FIG. 4 is a graph showing an example of another override characteristic.

FIG. 5 is a graph showing an example of another override characteristic.

[Explanation of symbols]

 12 injection screw 14 hydraulic pump 16 pressure sensor 18 keyboard 20 MPU 22 display 24 RAM 26 ROM

[Procedure amendment]

[Submission date] September 21, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. In the present embodiment, a control device of an injection molding machine suitable for carrying out the control method of the present invention will be described as an example. In the block diagram of FIG. 1, an injection screw 12 is driven by a hydraulic pump (hydraulic actuator) 14. Injection screw 12
Is disposed in a heating cylinder (not shown), and when driven by the hydraulic pump 14, the resin in a molten state in the heating cylinder is injected and filled into a molding die (not shown). The hydraulic pump 14 is provided with an electronic control unit including a flow rate control valve (not shown), and the control unit actuates the flow rate control valve according to an input control signal to control the flow rate of the hydraulic pump 14. A filling mechanism is configured so that the injection screw 12, the hydraulic pump 14 and the like fill the molding die with resin. In this embodiment, the advancing speed of the injection screw 12 is regarded as the filling speed of the resin into the molding die, and the advancing speed can be measured via a sensor (not shown).

Claims (14)

[Claims] 1. A method of measuring a load pressure of a molding machine, and controlling a filling mechanism to fill a resin into a molding die at a filling speed having a predetermined correlation with the measured load pressure. A method for controlling a molding machine, characterized by: 2. The molding machine according to claim 1, wherein the filling speed is calculated based on a measured load pressure according to a predetermined arithmetic expression having the correlation. Control method. 3. The filling rate is determined by searching a data table of the filling rate with respect to the stored load pressure, which is predetermined so as to have the correlation based on the measured load pressure. The method for controlling a molding machine according to claim 1. 4. The method of controlling a molding machine according to claim 1, wherein the load pressure is a hydraulic pressure of a hydraulic actuator for driving the filling mechanism. 5. The load pressure is a resin pressure charged in the filling mechanism.
Alternatively, the method of controlling the molding machine according to the item 3. 6. The method of controlling a molding machine according to claim 1, wherein the load pressure is a resin pressure in the molding die. 7. The method of controlling a molding machine according to claim 1, wherein the load pressure is obtained from a load of an electric motor for driving the filling mechanism. 8. A measuring means for measuring a load pressure of a molding machine, a storage means for storing the load pressure measured by the measuring means, and a load pressure stored in the storage means. Based on the load pressure, a filling speed having a predetermined correlation is obtained, and a control means for controlling the filling mechanism to fill the resin into the molding die at the obtained filling speed is provided. A molding machine control device characterized by the above. 9. A calculation means for calculating the filling speed by calculation is provided, wherein the control means has a predetermined calculation formula that has the correlation based on the load pressure stored in the storage means. The control device for a molding machine according to claim 8, wherein the filling speed is calculated according to the above. 10. A data table of a filling speed with respect to the load pressure having the correlation is stored in advance in the storage means, and the control means stores the load pressure based on the load pressure stored in the storage means. 9. The molding machine controller according to claim 8, wherein the filling speed is obtained by searching a data table. 11. The molding machine control device according to claim 8, wherein the load pressure is a hydraulic pressure of a hydraulic actuator for driving the filling mechanism. 12. The load pressure is a resin pressure with which the filling mechanism is filled.
The control device for a molding machine according to 9 or 10. 13. The load pressure is a resin pressure in the molding die.
The control device of the molding machine according to 0. 14. The molding machine control device according to claim 8, wherein the load pressure is obtained from a load of an electric motor for driving the filling mechanism.