JPS62275730A - Method for controlling injection molder - Google Patents

Abstract

PURPOSE:To prevent the deviation from developing and, in addition, improve the responsiveness to disturbance by a method wherein the setpoint set on the control object of an injection molder is corrected by a correction value obtained on the basis of the disturbance applied on said controlled system. CONSTITUTION:When the temperature of resin 7 rises due to the heat generated by shearing, a change in temperature is detected by a temperature detector 6. The amount of the temperature change is inputted to a control unit 1. The amount of the change in conduction corresponding to the detected amount of the temperature change is calculated in accordance with the pattern of the change in the amount of current flow by a predictor (not shown) in the control unit 1 and issued as a correction value of current flow. In the control unit 1, the setpoint of the amount of current flow is corrected by the correction value of current flow and outputted in the form of the corrected setpoint of conduction. The conduction rate of a band heater 5 is controlled by the above-mentioned corrected setpoint of current flow and consequently the corrected amount in the corrected setpoint of current flow and the amount of the change the temperature of a cylinder due to the amount of the change in the resin temperature cancel each other, resulting in keeping the temperature of the cylinder at the setpoint.

Description

[Detailed description of the invention] 3. Detailed description of the invention (Industrial application field) The present invention relates to controlling an injection molding machine.

(Conventional technology) In an injection molding machine, the material resin is melted in a 7-liner,
This molten resin is injection molded into a mold cavity. Therefore, the temperature of the cylinder, and how well the injection pressure and holding pressure of the molten resin are controlled have a great effect on the molded product.

Therefore, for example, to control the temperature of a cylinder, the temperature of the cylinder is detected by a temperature sensor.

Feedback control is used to maintain the cylinder temperature at a set value based on this detected temperature.

Similarly, for injection pressure control and pressure holding control of molten resin, the hydraulic pressure is detected and the relief valve, siren valve, etc. are controlled based on this detected pressure to maintain the set injection pressure and holding pressure. As such, feedback control is used.

(Problems to be Solved by the Invention) For example, as shown in FIGS. 4(a) and 4(b), in the case of cylinder temperature control, shear heat generation or the like is used.

When the resin temperature rises, the cylinder temperature rises after 1 hour. This temperature change in the cylinder is detected by a temperature sensor, and the power supply to the cylinder is controlled based on the amount of temperature change. That is.

When the amount of electricity supplied to the cylinder is reduced and the cylinder temperature is controlled to the set value, the resin temperature gradually decreases after one hour. Then, as the resin temperature decreases, the cylinder temperature decreases.

The cylinder temperature drops below the set value.

When a disturbance occurs in this way, it becomes impossible to maintain the cylinder temperature at the set value.

Furthermore, since the resin temperature also changes greatly due to a change in cylinder temperature, there is a problem in that many molded products are defective.

As mentioned above, the conventional control method has a problem in that it is not quick to respond to disturbances, and deviations always occur.

(Means for Solving the Problem) In the method for controlling an injection molding machine according to the present invention, a setting value set for a controlled object of the injection molding machine is corrected by a correction value determined based on a disturbance applied to the controlled object. The feature is that it is made to look like this.

That is, as shown in FIG. 1, the control device 1 includes a predictor 1a.
This predictor 1& stores changes and turns of the controlled object due to disturbances.

Therefore, when a disturbance occurs, the predictor 1a outputs a correction value based on this disturbance according to a change pattern.

Then, in the control device 1, the set value is corrected using this correction value, and the corrected set value is output. Therefore, the controlled object 2 is controlled based on this correction value, and the object is controlled to a predetermined set value.

(Example) The present invention will be explained below with reference to Examples.

In this embodiment, temperature control of the cylinder will be explained.

Referring to FIG. 2, a screw 4 is disposed inside the cylinder 3 so as to be slidable in the axial direction, and a band heater 5 is attached to the outer circumferential surface of the cylinder 3 to constitute a cylinder device. A temperature sensor 6 is installed on the inner peripheral surface of the cylinder 3.
A temperature detection end 6a is provided, and the temperature detector 6 is connected to the control device 1. The control device 1 then controls the amount of electricity supplied to the band heater 5 to maintain the temperature of the cylinder 3 at a set value input to the control device 1.

Now, when the temperature of the resin 7 rises due to shear heat generation, this temperature change is detected by the temperature detector 6.

This temperature change amount is input to the control device 1. Control device 1
A predictor (not shown) inside calculates the amount of change in temperature and the amount of change in energization from the change in energization amount and the set turn.

This energization change amount is generated as an energization correction value. and,
In the control device 1, the one energization amount setting value is corrected by the energization correction value and output as a corrected energization setting value. That is, when the resin temperature rises, the energization correction value corresponding to the amount of temperature change is subtracted from the energization amount setting value, and the corrected energization setting value is output. on the other hand.

When the resin temperature drops, an energization correction value corresponding to the amount of temperature change is added to the energization setting value.

The amount of energization to the band heater 5 is controlled by the above-mentioned corrected energization setting value, and the correction amount of the corrected energization setting value and the amount of change in cylinder temperature due to the amount of change in resin temperature are offset. , the cylinder temperature is maintained at the set value.

As mentioned above, the energization correction value is calculated from the energization amount change pattern that indicates the relationship between the temperature change amount and the energization change amount from the resin temperature change continuously detected by the temperature detector 6, and the energization correction value is used to calculate the energization correction value for one energization. The setting amount is being corrected. That is, the energization setting value is continuously corrected in response to resin temperature changes, and the amount of energization to the band heater is adjusted based on the corrected energization setting value.

In other words, since the amount of heat generated by the band heater is set, even if the resin temperature rises due to shear heat, as shown in Figures 3 (a) and (b), the cylinder temperature will still be the same as the set amount of current applied to the band heater. (i.e., a predetermined set temperature). Therefore.

Temperature changes in the resin can be suppressed slightly, and good molded products can be obtained.

In addition, in the above-mentioned embodiment, the temperature control of the cylinder was described, but injection pressure control, pressure holding control, etc. can be similarly performed (i.e., by feedforward control).
Can be controlled.

(Effects of the Invention) As explained above, according to the control method according to the present invention,
The controlled variable can always be maintained at the set value, so no deviation occurs. Additionally, the response to disturbances is extremely good.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the present invention in detail, FIG. 2 is a diagram showing an embodiment in which the present invention is applied to cylinder temperature control, and FIG. 3 (, ) and (b) are diagrams each showing the present invention Figure 4 shows the resin temperature and cylinder temperature when using
) and (b) are diagrams showing the resin temperature and cylinder temperature, respectively, using the conventional method. 1...Control device, 2...Controlled object, 3...Cylinder. 4... Suf IJx-, 5... Band heater, 6...
・Temperature test Figure 1 Figure 2 Temperature value Figure 3 Temperature of the intestine (b) Temperature of the fat (Q) Figure 4 Temperature of the fat (Q)? poetry questions

Claims (1)

[Claims] 1. In an injection molding machine that injects molten resin from a cylinder into a mold cavity for molding, the setting value set for the control object of the injection molding machine is corrected by a correction value determined based on the disturbance applied to the control object. A method for controlling an injection molding machine, characterized in that: