JP3495796B2 - Position control method and apparatus for electric 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 and apparatus for controlling the position of an electric injection molding machine, and more particularly to a coefficient for multiplying the deviation when the deviation between the position command and the position signal is less than a set value. The present invention relates to a novel improvement for performing smooth position control with less vibration of the machine by making the coefficient smaller than the coefficient applied at a larger time.

[0002]

2. Description of the Related Art A position control device for an electric injection molding machine of this type which has been conventionally used generally has a structure shown in FIG. That is, the injection screw 2 in the cylinder 1 is injected and rotated by the servomotor 4 via the transmission mechanism 3, and the speed pulse signal 6 from the pulse encoder 5 of the servomotor 4 is connected to the servomotor 4. It is input to the servo motor amplifier 7 and the counter 9 of the position control device 8 which are generated.

Counter output 9a from the counter 9
Is input to the subtractor 11 as a position signal 10a indicating the current position of the injection screw 2 in the D / A converter 10, and the subtractor 11 is instructed to the position of the injection screw 2 from the controller 12. The position command 13 is input. The speed gain switching signal 14 from the controller 12 is input to the servo motor amplifier 7 for switching the gain of the servo motor amplifier 7.

The deviation 15 which is the subtraction result of the subtracter 11
Becomes a value controlled by the proportional-plus-integral controller 16 and is input to the servo motor amplifier 7 as a speed command 17, and the speed command 17 drives the servo motor 4.

[0005]

When a control called a servo lock is performed in which the servo motor is stopped at an arbitrary position with a constant position command in the conventional control configuration,
If the servo motor amplifier is adjusted to a speed gain that optimizes the dynamic characteristics of the servo motor, the speed gain may be too high when the servo lock control is performed, and vibration may occur in the machine. In this way, when performing servo lock control, the controller outputs a speed gain switching signal that reduces the speed gain, and this signal causes the servo amplifier to reduce the speed gain, which suppresses vibration. Had a complicated configuration.

The present invention has been made to solve the above problems, and in particular, a coefficient to be applied to the deviation when the deviation between the position command and the position signal is less than or equal to a set value is a deviation from the set value. An object of the present invention is to provide a position control method and device for an electric injection molding machine, which is configured to perform a smooth position control with less vibration of the machine by making the coefficient smaller than the coefficient when it is large.

[0007]

In a position control method for an electric injection molding machine according to the present invention, a deviation between a position command and a position signal is calculated, a calculation is performed based on the deviation to determine a speed command, and an injection screw of the injection screw is determined. In a position control method for an electric injection molding machine that performs position control, the coefficient to be multiplied by the deviation when the deviation is less than or equal to a set value is made smaller than the coefficient when the deviation is greater than the set value to perform position control. Is the way to do it.

A position control device for an electric injection molding machine according to the present invention calculates a deviation between a position command and a position signal, performs a control calculation based on the deviation, determines a speed command, and controls the position of the injection screw. In the position control device of the electric injection molding machine described above, the gain adjuster is connected to a subtractor that calculates the deviation, and the gain adjuster is a coefficient to be applied to the deviation when the deviation is equal to or less than a set value. Can be made smaller than a coefficient to be multiplied when the deviation is larger than a set value.

A position control device for an electric injection molding machine according to the present invention calculates a deviation between a position command and a position signal, performs a control calculation based on the deviation, determines a speed command, and controls the position of the injection screw. In the position control device of the electric injection molding machine according to the above, there is a calculation unit for performing the calculation and the control calculation of the deviation and for inputting the position command and the position signal. This is a configuration in which the coefficient multiplied by the deviation at time can be calculated by a control algorithm for making it smaller than the coefficient multiplied when the deviation is larger than a set value.

[0010]

In the position control method and apparatus for the electric injection molding machine according to the present invention, the deviation between the position command and the position signal is calculated, and the coefficient by which the deviation is equal to or less than the set value is calculated.
By performing the position control by making the coefficient smaller than the coefficient applied when the deviation is larger than the set value, the speed gain switching function in the servo amplifier becomes unnecessary, and the vibration of the machine at the completion of weighing and the completion of suckback is eliminated. The number is reduced, and smooth position control becomes possible.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a position control method and apparatus for an electric injection molding machine according to the present invention will be described in detail below with reference to the drawings. It should be noted that the same or equivalent parts as those of the conventional example will be described by attaching the same reference numerals. 1 and 2 are for explaining a position control method and device for an electric injection molding machine according to the present invention, and since the configuration other than the position control device 8 shown in FIG. 3 is the same, the configuration of FIG. 3 is referred to. And The subtractor 11 provided on the input side of the position control device 8 in FIG.
The position command 13 from the controller 12 is input, the speed pulse signal 6 from the pulse encoder 5 is input to the counter 9 and counted, and the subtraction is performed via the D / A converter 10 as the position signal 10a of the analog signal. Is input to the device 11.

The deviation 15 between the position command 13 from the subtractor 11 and the position signal 10a (representing the current position of the injection screw 2) is input to the gain adjuster 20 provided in the position control device 8. . In the gain adjuster 20, the coefficient applied to the deviation 15 when the deviation 15 is equal to or less than a set value (not shown) is controlled to be smaller than the coefficient applied when the deviation 15 is larger than the set value (built-in control algorithm The corrected deviation 15a after the gain adjustment is input to the servo motor amplifier 7 as a speed command 17 via the proportional-plus-integral controller 16.

Therefore, in the position control device 8 described above, conventionally, the servo motor amplifier 7 receives the speed gain switching signal 14 and controls the gain adjusting function for changing the gain by the control algorithm in the gain adjuster 20. Therefore, the configuration of the servo motor amplifier 7 used in the present invention does not have the gain adjusting function and does not require the input of the speed gain switching signal 14.

Next, the structure shown in FIG. 2 shows another embodiment of FIG. 1, and the same parts as those in FIG.
Although the description is omitted, unlike the hardware configuration of FIG. 1, it is configured by software processing using an arithmetic unit 30 including a CPU.

Therefore, the position command 13 is taken into the arithmetic unit 30 via the interface 31, and the position signal 10a from the counter 9 is taken in at the same time, which is built into the memory 32 and built into the gain adjuster 20. The same control algorithm as that called is called by the arithmetic unit 30 and loaded. Based on the above-mentioned control algorithm, the calculation unit 30 calculates a coefficient to be multiplied by the deviation 15 when the deviation 15 is equal to or less than a set value (not shown)
Is smaller than the coefficient applied when is larger than the set value, and the corrected deviation 15a after gain adjustment is output to the servo motor amplifier 7 via the common bus 40 and the D / A converter 41 as a speed command 17 composed of an analog signal.

In each of the above-described embodiments, the case where the deviation 15 when the deviation is less than the set value is set to be smaller than the coefficient when the deviation is larger than the set value is described. Contrary to the above, although not shown in the figure, by performing a control process that raises the gain when the deviation exceeds an arbitrary value, the control algorithm obtains a speed gain whose rigidity is adjusted relatively gently. In the case of servo lock control, it can also be used for the purpose of increasing the rigidity by locking firmly.

[0017]

Since the position control method and apparatus for the electric injection molding machine according to the present invention is configured as described above, the speed gain switching signal from the controller is unnecessary and the servo amplifier side also has a speed gain. The mechanism for switching is unnecessary. Further, at the time of completion of weighing, completion of suck back, etc., vibration of the machine is reduced, smooth position control becomes possible, and high-quality injection molding becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an apparatus to which a position control method for an electric injection molding machine according to the present invention is applied.

FIG. 2 is a block diagram showing another embodiment of FIG.

FIG. 3 is a block diagram showing an apparatus to which a conventional position control method is applied.

[Explanation of symbols]

2 injection screw 11 Subtractor 10a Position signal 13 Position command 15 deviation 20 gain adjuster

Claims (3)

(57) [Claims] 1. A deviation between the position command (13) and the position signal (10a)
In the position control method of the electric injection molding machine, the position control of the injection screw (2) is performed by calculating (15) and determining the speed command (17) by performing the calculation based on the deviation (15). Position control is performed by making the coefficient applied to the deviation (15) when the deviation (15) is less than or equal to a set value smaller than the coefficient applied when the deviation (15) is greater than the set value to perform position control. Position control method of machine. 2. A deviation between the position command (13) and the position signal (10a)
In the position control device of the electric injection molding machine, which calculates (15), performs the control calculation based on the deviation (15), determines the speed command (17), and controls the position of the injection screw (2). It has a gain adjuster (20) connected to a subtractor (11) for calculating the deviation (15), the gain adjuster (20), the deviation when the deviation (15) is less than or equal to a set value. A position control device for an electric injection molding machine, characterized in that the coefficient applied to (15) can be made smaller than the coefficient applied when the deviation (15) is larger than a set value. 3. A deviation between the position command (13) and the position signal (10a)
In the position control device of the electric injection molding machine, which calculates (15), performs the control calculation based on the deviation (15), determines the speed command (17), and controls the position of the injection screw (2). A calculation unit (30) for inputting the position command (13) and the position signal (10a) while performing the calculation of the deviation (15) and the control calculation.
The calculation unit (30) has a coefficient to be multiplied by the deviation (15) when the deviation (15) is less than or equal to a set value, smaller than a coefficient by which the deviation (15) is greater than the set value. A position control device for an electric injection molding machine, wherein the position control device is configured so that it can be calculated by a control algorithm.