JP2919128B2 - Control method of proportional electromagnetic control valve of injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a proportional electromagnetic control valve of an injection molding machine, and more particularly to a method for automatically correcting a characteristic variation of a proportional electromagnetic control valve for controlling speed or pressure. The present invention relates to a method for controlling a proportional electromagnetic control valve of an injection molding machine for performing operation control.

[0002]

2. Description of the Related Art In an injection molding machine, pressure oil from a hydraulic pump or an accumulator is supplied to a hydraulic cylinder (injection cylinder, mold clamping cylinder, mold clamping cylinder) through a proportional electromagnetic control valve (proportional electromagnetic flow control valve or proportional electromagnetic pressure control valve). , A nozzle touch cylinder, etc.) to control the speed or pressure. However, the proportional electromagnetic control valve generally has large variations in its characteristics. For this reason, the characteristics of the proportional electromagnetic control valve mounted on the machine (injection molding machine) are actually measured before the machine is shipped, and a correction characteristic table of the command value ⇔ output value is created based on the results of the actual measurement. Is a technique for controlling the proportional electromagnetic control valve with reference to the contents of the correction characteristic table.
No. 7 discloses this. In the method for automatically correcting the characteristics of a proportional electromagnetic control valve shown in the prior application, the input value is sequentially changed from a minimum input value to a maximum input value to operate the proportional electromagnetic control valve, and a large number of output values corresponding to this are firstly changed. The correction characteristic table is created so that the output value is proportional to the input value based on the results of actual measurement and the grasp of the relationship between the large number of actually measured values and the corresponding command values.

[0003]

By the way, in the above-mentioned prior art, many points from the minimum output value to the maximum output value of the proportional solenoid control valve are actually measured and plotted when creating the correction characteristic table. Due to restrictions on the use of hydraulic cylinders, it may not be possible to output the maximum pressure and maximum speed when the proportional solenoid control valve is mounted on the machine. Only output of several tens% or less can be output). For this reason, in such a case, there is a problem that the characteristic of the proportional electromagnetic control valve cannot be corrected by the conventional technique.

[0004] Therefore, a technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to set a maximum pressure or a pressure when a proportional electromagnetic control valve is mounted on a machine. An object of the present invention is to provide a control method of a proportional electromagnetic control valve of an injection molding machine that can automatically correct a characteristic variation of a proportional electromagnetic control valve for controlling a speed or a pressure even when a maximum speed cannot be obtained.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention supplies pressure oil from a hydraulic pump or an accumulator to a hydraulic actuator such as an extraction cylinder through a proportional electromagnetic control valve to control the speed. Alternatively, in the method of controlling the proportional electromagnetic control valve of the injection molding machine in which the pressure is controlled, the system controller that controls the entire injection molding machine requires a request to automatically correct the characteristic of the proportional electromagnetic control valve mounted on the injection molding machine. When instructed, the proportional electromagnetic control valve is operated by predetermined two arbitrary command values to measure the operation output values based on the arbitrary two command values, respectively. In addition, the relationship between the actually measured output value, the command value over substantially the entire range of the proportional solenoid control valve of the same type as the proportional solenoid control valve that performs the characteristic automatic correction, and the corresponding output value is predicted. Nonlinear standard characteristics table storing
With reference to the reference characteristic curve data of the shape, the relationship between the command value over substantially the entire range of the proportional solenoid control valve mounted on the injection molding machine and the corresponding output value is calculated, and based on this,
A correction characteristic table having non-linear correction characteristic curve data is created, and the subsequent operation control of the proportional electromagnetic control valve is performed using the contents of the correction characteristic table.

[0006]

[Function] In a suitable storage area of a system controller (microcomputer) that controls the entire machine (injection molding machine), reference characteristic data (shown by a manufacturer) of a proportional electromagnetic control valve of the same type as a proportional electromagnetic control valve mounted on the machine is stored. The reference characteristic table in which the stored valve characteristic data is stored is created in advance. When the microcomputer requests the microcomputer to automatically correct the characteristics of the proportional electromagnetic control valve before the machine is shipped, the microcomputer sets the proportional electromagnetic control valve to any two predetermined command values (for example, 5% input value and 20% input value). % Input value), and the corresponding output values (pressure and speed) are measured. Thereafter, the microcomputer reads the relationship between the command value and the output value of the two points by this test operation, the command value over substantially the entire range of the proportional electromagnetic control valve, and the actually measured output value corresponding thereto in advance. Contents (reference characteristic curve data)
, The output values corresponding to the 5% input value and the 20% input value on the reference characteristic curve are replaced with the measured output values, and correspond to the input values of other points on the reference characteristic curve. The output values are sequentially calculated based on the two correction amounts to re-create a characteristic curve, thereby rewriting the contents of the reference characteristic table (reference characteristic curve data) with the correction characteristic curve data to create a correction characteristic table. Thereafter, the microcomputer controls the operation of the proportional electromagnetic control valve in accordance with the contents of the correction characteristic table (correction characteristic curve data), thereby correctly outputting the set pressure and the set speed regardless of the characteristic variation of the proportional electromagnetic control valve. The input value (current value) for this is supplied to the proportional electromagnetic control valve, and the desired operating condition control is executed. If it is necessary to readjust the characteristics of the proportional electromagnetic control valve due to aging or valve replacement, the contents of the corrected characteristic table created before shipment are used as the original characteristic curve data in the same manner as described above. Then, the content of the characteristic table is rewritten and updated again.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a simplified block diagram of a control system of the injection molding machine according to the present embodiment. In FIG. 1, reference numeral 1 denotes a microcomputer (a microcomputer serving as a system controller) that controls the operation and display of the entire machine (injection molding machine), 2 denotes a sensor group including a large number of sensors provided in each part of the machine, Reference numeral 3 denotes a driver group composed of a large number of driver circuits for driving and controlling a large number of drive sources provided in each part of the machine. 4 denotes a key input device provided on the front of the machine. For example, a color CRT display, a color L disposed adjacent to the input device
It is a display device composed of a CD or the like.

[0008] The microcomputer 1 of FIG.
Control of the entire molding process such as injection operation, mold opening / closing operation, and eject operation, calculation / storage processing of measured data, determination processing of non-defective / defective products, calculation / determination processing such as abnormality determination processing, or processing of the display device 5 Various processes such as output image display control processing are executed. This microcomputer 1 actually has various I
In the present embodiment, a molding condition setting storage unit 11 and a molding process control unit 12 are used to execute various types of processing by using various programs created in advance. The following description will be made assuming that the apparatus includes the measured value storage unit 13, the display processing unit 14, the control valve characteristic calculation processing unit 15, and the like.

Various operating condition values input by the key input device 4 or the like are stored in the molding condition setting storage unit 11 in a rewritable form. The operating condition values include, for example, the tightening force, the relationship between the screw position and the screw rotation speed during the charge stroke, the screw retreat speed, and the back pressure, suckback control conditions, and the injection speed from the start of injection to the holding pressure switching. Conditions, primary injection pressure conditions, secondary pressure (holding pressure) switching conditions, holding pressure conditions from the time of holding pressure switching to the end of holding pressure, band heater temperatures of each part, mold closing (mold closing) stroke and speed control Conditions, mold clamping force, mold opening stroke and speed control conditions, eject control conditions,
Nozzle touch / nozzle back control conditions, and the like.

[0010] The molding process control section 12 is based on the molding process control program created in advance and the setting condition values stored in the molding condition setting storage section 11, and the sensor group 2 provided in each section of the machine. The driver group 3 (motor) is referred to by referring to information from an actually measured value storage unit 13 which stores measurement information from a position sensor, a pressure sensor, a temperature sensor, and the like in real time, and time measurement information from a clock incorporated therein. A corresponding drive source is driven and controlled via a driver, a hydraulic valve driver, a heater driver, etc., and a series of molding steps are executed.

In FIG. 1, a part of the hydraulic circuit of the machine is shown in a simplified manner.
Is a hydraulic cylinder, 22 is a proportional electromagnetic control valve, and 23 is a hydraulic pump. The proportional electromagnetic control valve 22 has its valve opening controlled by a corresponding valve driver circuit in the driver group 3, and the pressure from the hydraulic pump 23 is The oil is supplied to the hydraulic cylinder 21 to control, for example, the pressure. The hydraulic cylinder 21 is provided with a pressure sensor 24 in the sensor group 2, and the operating pressure of the hydraulic cylinder 21 is sensed by information measured by the pressure sensor 24. In addition, actually, a plurality of hydraulic cylinders, a proportional electromagnetic pressure control valve, a proportional electromagnetic flow rate (speed) control valve, a pressure sensor, an encoder (stroke detection sensor) for measuring speed, and the like are provided. In this embodiment, for simplification of description, only the proportional electromagnetic control valve 22 for pressure control and members related thereto are shown as representatives.

The actually measured value storage section 13 stores all actually measured data of preset monitor items during continuous automatic operation over a predetermined number of consecutive shots. The monitored items to be captured include a time monitoring item, a position monitoring item, a rotation speed monitoring item, a speed monitoring item, a pressure monitoring item, a temperature monitoring item, a power monitoring item, and the like. Are almost overlapped.

The display processing section 14 displays display image data of a designated display mode based on a display image creation / control program created in advance by a command to call a display image in a mode desired by the operator via the key input device 4. Create That is, when a call instruction of a predetermined display image by the operator arrives, the display processing unit 14
If necessary, data for use in displaying the display mode image is extracted from the information stored in the molding condition setting storage unit 11 or the actual measurement value storage unit 13, and the display mode of the display mode image in which these are designated is extracted. Is converted to a form corresponding to. For example, if the designated display mode is a graphic image of a certain process, the extracted data is converted into image data that has been subjected to line drawing at a predetermined enlargement / reduction ratio, or the designated display mode is a certain display mode. If the image is an operation state setting image of a process, the extracted data is converted into numerical image data. Further, the display processing unit 14 extracts data to be used for displaying the display mode image, from fixed data for many mode images, such as characters, symbols, graphic figures, and ruled line data, which are created and stored in advance. Then, the fixed data and the converted image data are combined to create image data for a designated display mode, and this is displayed on the display screen of the display device 5.

The control valve characteristic calculation processing section 15 has a function of automatically correcting and calculating a characteristic curve of each proportional electromagnetic control valve mounted on the machine in accordance with an instruction of an operator. The unit 15 includes a relation between a command value (input current (voltage) value) over the entire range of each proportional electromagnetic control valve including the proportional electromagnetic control valve 22 and an output value (pressure or speed) corresponding thereto, that is, Control valve characteristic storage table 15a for storing each control valve characteristic curve data
Is built-in. This control valve characteristic storage table 15a
In the uncorrected stage before shipment, each reference characteristic curve data (valve characteristic curve data indicated by the manufacturer) of the proportional electromagnetic control valve of the same type as each proportional electromagnetic control valve mounted on the machine is stored. In this state, the control valve characteristic storage table 15a is a so-called uncorrected reference characteristic table.

Then, in this state, the operator calls a characteristic automatic correction instruction image of the proportional electromagnetic control valve by a predetermined key operation with the key input device 4, and instructs a collective automatic correction of the characteristic of the proportional electromagnetic control valve on this display image. , Microcomputer 1
Is set to a valve characteristic automatic correction mode, and sequentially operates the respective proportional electromagnetic control valves disposed in each section of the machine according to a preset program. That is, the microcomputer 1 controls the molding process control unit 12 to operate each proportional electromagnetic control valve according to predetermined two command values (for example, 5% input value and 20% input value), The corresponding output values (pressure and speed) are measured and stored in the measured value storage unit 13. As a result, the control valve characteristic calculation processing unit 15 refers to the command value and the actually measured output value of the two points by the test operation and the reference characteristic curve data (contents of the control valve characteristic storage table 15a) of each proportional electromagnetic control valve. Then, the output values corresponding to the 5% input value and the 20% input value on the reference characteristic curve are replaced with the measured output values, and further, the output values corresponding to the input values of other points on the reference characteristic curve Are sequentially calculated based on the correction amounts of the above two points to re-create a characteristic curve.
The content of 5a is rewritten from the reference characteristic curve data to the correction characteristic curve data. Thereafter, the microcomputer 1 controls the operating conditions of the pressure and speed input and set by the operator in accordance with the contents (corrected characteristic curve data) of the corrected control valve characteristic storage table 15a, thereby obtaining the characteristic of the proportional electromagnetic control valve. Regardless of the variation, an input value (current value) for correctly outputting the set pressure and the set speed is supplied to each proportional electromagnetic control valve, and the desired operation condition control is executed.

FIG. 2 is a view for explaining the principle of the correction processing executed by the control valve characteristic calculation processing section 15. In FIG. 2, reference numeral 31 denotes a proportional type having the same model as, for example, the proportional electromagnetic control valve 22 supplied from a manufacturer. It is a reference characteristic curve of an electromagnetic control valve. Assuming that the actual output values (pressure values) corresponding to the input current values xa and xb are ya and yb, the points A1 and B1 on the reference characteristic curve 31 are corrected to shift to the points A2 and B2, respectively. Then, other points (for example, point N1) on the reference characteristic curve 31 are also shifted (for example, point N2) according to the correction amounts of A1 → A2 and B1 → B2, whereby the correction characteristic curve 32 is created.

FIG. 3 is a diagram for explaining a calculation method for interpolating and correcting the characteristic curve using the reference characteristic curve 31 and the actually measured data. Now, two points (x1, y1) and (x2, y2) on the reference characteristic curve 31 become (x1, y1,
y11), (x2, y22) (x = x1
If the measured output value at time x is x11 and the measured output value at x = x2 is y22), an output correction value corresponding to x = x0 at an arbitrary point (x0, y0) on the reference characteristic curve 31 y = y00 is obtained by y00 = y0 + [(y11-y1) (x2-x0) + (y22-y2) (x0-x1)] / (x2-x1). By using such a calculation method, an output correction value corresponding to an arbitrary point on the reference characteristic curve 31 is sequentially obtained, whereby a correction characteristic curve 32 is generated, and the content of the control valve characteristic storage table 15a is changed to the reference characteristic. The curve data is rewritten to the correction characteristic curve data.

If it is necessary to readjust the characteristics of the proportional electromagnetic control valve due to aging or valve replacement, the corrected control valve characteristic storage table 15a created before shipment is prepared in the same manner as described above. With the contents as the original characteristic curve data,
The content of the control valve characteristic storage table 15a is rewritten again.
Be updated.

FIG. 4 shows a schematic processing flow of the control valve characteristic correction processing executed by the microcomputer 1. In step S1 shown in FIG. 4, storage of characteristic data of the proportional electromagnetic control valve issued from the manufacturer is performed. Is performed, and in step S2, the above-mentioned arbitrary two points are measured. In step S3, 2 points are measured.
All the characteristic data of the proportional solenoid control valve mounted on the machine is re-created using the actual measurement data of the point and the original characteristic data. In step S4, the machine is operated using the re-created characteristic line data. Thereafter, when it is necessary to readjust the characteristics of the proportional electromagnetic control valve, the process returns to step S2.

[0020]

As described above, according to the present invention, the predetermined
Command value and measured output value by two point measurement of two points
And the non-linear reference characteristic of the reference characteristic table stored in advance
Refer to the curve data and the nonlinear correction characteristic curve data
To create a correction characteristic table with
Proportional solenoid with the same model as the proportional solenoid control valve that performs automatic correction
Command values and corresponding outputs over almost the entire range of the control valve
Stores non-linear reference characteristic curve data related to values.
Has a reference characteristic table,
Is non-linear due to simple measurement operation
Even with correction characteristic curve data, this can be easily calculated and generated.
Can be achieved. Therefore, the proportional solenoid control valve
When the maximum pressure and maximum speed cannot be achieved while mounted on the thin
Proportional electromagnetic control by simple and easy two-point measurement
It is now possible to automatically correct all nonlinear characteristic curves of valves.
Output the correct pressure and speed for the set value.
Can be. Further, the reference characteristic table is used for the correction.
The contents are rewritten and updated to become a characteristic table.
The proportional solenoid control valve
If it becomes necessary to readjust the characteristics of the
The contents of the created correction characteristic table are used as the original characteristic curve data.
As a result, the correction characteristic table can be obtained again.
You. Therefore, the capacity of the memory for storing the characteristic curve data
The quantity does not increase unnecessarily and is necessary after shipment
According to the machine itself (injection molding machine), the correction characteristics at any time
A new table can be created.

[Brief description of the drawings]

FIG. 1 is a simplified block diagram of a control system of an injection molding machine according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the principle of a control valve characteristic correction process according to the present invention.

FIG. 3 is an explanatory diagram for assisting in understanding a correction calculation of control valve characteristics according to the present invention.

FIG. 4 is an explanatory diagram showing a schematic process flow of a control valve characteristic correction process executed by the microcomputer according to one embodiment of the present invention.

[Description of Signs] 1 microcomputer (microcomputer) 2 sensor group 3 driver group 4 key input device 5 display device 11 molding condition setting storage unit 12 molding process control unit 13 measured value storage unit 14 display processing unit 15 control valve characteristic calculation processing Unit 15a Control valve characteristic storage table 21 Hydraulic cylinder 22 Proportional electromagnetic control valve 23 Hydraulic pump 24 Pressure sensor

Claims (2)

(57) [Claims] 1. An injection molding machine for supplying pressure oil from a hydraulic pump or an accumulator to a hydraulic actuator such as a hydraulic cylinder via a proportional electromagnetic control valve to control the speed or pressure. The system controller that controls the entire system
When a request for automatic correction of the characteristics of the proportional electromagnetic control valve mounted on the injection molding machine is issued, the proportional electromagnetic control valve is operated by predetermined two arbitrary command values, and the arbitrary two command values are set. The operation output value is measured respectively, and the command value at any two points and the actually measured output value, and the command value over substantially the entire range of the proportional electromagnetic control valve and the type common to the proportional electromagnetic control valve performing the characteristic automatic correction and A non-linear reference characteristic song of a reference characteristic table in which a relation with an output value corresponding thereto is stored in advance.
With reference to the line data , the relationship between the command value over substantially the entire range of the proportional solenoid control valve mounted on the injection molding machine and the corresponding output value is calculated, and based on this, the nonlinear correction characteristic is calculated.
A control of the proportional electromagnetic control valve of the injection molding machine, characterized in that a correction characteristic table having the characteristic curve data is prepared, and the operation control of the proportional electromagnetic control valve thereafter is performed using the contents of the correction characteristic table. Method. 2. The method according to claim 1, wherein the contents of the proportional characteristic control valve of the injection molding machine are rewritten and updated so that the reference characteristic table becomes the correction characteristic table.