JP2793890B2 - Insulation control method for injection molding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dwell control method for an injection molding machine.

(Prior Art) Conventionally, a molding material heated and fluidized in a heating cylinder is injected into a mold under high pressure, cooled and solidified or cured therein, and then the mold is opened to remove a molded product. An injection molding machine as shown in FIG. 4 is provided.

 FIG. 4 is a schematic view of a conventional injection molding machine.

That is, a mold clamping device 12 and an injection device 13 are provided on the machine base 11, and the mold clamping device 12 includes a fixed platen 14 and a movable platen 15. When the movable platen 15 is reciprocated along the tie bar 17 by the mold clamping cylinder 16, the fixed mold 18 and the movable mold 19 are moved toward and away from each other.

Further, the injection device 13 has a molding material in a hopper 20,
That is, a nozzle 21 for heating, melting, and injecting the resin to reciprocate is disposed so as to be able to reciprocate. The nozzle 21 injects the molten resin into the mold concave portions 18a, 19a. On the other hand, the molded article is dropped from the discharge port 22 below the machine base 11 and discharged.

By the way, in the above-mentioned injection molding machine, the movable mold 19 reciprocates each time molding is performed, and the movable mold 19 is brought into contact with and separated from the fixed mold 18 which is arranged to face. Therefore, reciprocating the movable mold 19 at high speed is important for improving molding efficiency.

Therefore, a mold clamping cylinder 16 is provided to reciprocate the movable mold 19 and generate a force for pressing the movable mold 19 against the fixed mold 18, that is, a mold clamping force.
Then, when the molten resin is injected into the concave portions 18a, 19a, the mold is closed, and subsequently, the mold is closed so that the injected resin does not leak.

When the injection of the resin is completed, the screw is maintained as it is, and a pressure holding step is started, and the resin pressure at that time is maintained for a while. This pressure-holding step includes a pressure-holding pressure maintained at a slightly higher pressure for solidifying the surface layer portion of the molded product, a pressure-holding pressure set at a high pressure for solidifying the inside of the molded product, and a gate pressure of the molded product. The pressure is divided into a holding pressure set to a lower pressure for solidifying a nearby portion, and the pressure is set to a plurality of stages.

Then, after the pressure-holding step is completed, the cooling step is started, and the cooling of the molded article is started. When the cooling step is completed,
The molding is completed and the molded product is taken out.

(Problems to be Solved by the Invention) However, in the above-described conventional injection molding machine, after the pressure-holding step is completed, no special pressure control is performed, so that the pressure in the final stage of the pressure-holding step is high. When the pressure is released, the screw is pushed back by the reaction force of the resin.

Therefore, the screw position at the start of weighing cannot be stabilized, and a difference occurs in the weighing state for each shot.
The quality of the molded product varies.

The present invention solves the above-mentioned problems of the conventional injection molding machine, provides a screw position at the start of weighing, and provides a method for controlling the dwelling pressure of the injection molding machine without causing variations in the quality of molded products. The purpose is to:

(Means for Solving the Problems) For this purpose, in the pressure holding control method of the injection molding machine of the present invention, the pressure is changed with the passage of time based on the output signal output from the pressure holding setting generator. When the pressure is held in multiple stages and the pressure holding in the final stage is completed, after the pressure holding completion signal is generated, it is detected that the actual pressure has become lower than the set value, or the preset time has elapsed. The output signal is output until at least one of the conditions is satisfied, the setting of the pressure holding stage is added, the pressure control with the pressure set value set to 0 is continued, and the measurement is started after the pressure control is completed. I do.

(Operation) According to the present invention, in the pressure holding control method of the injection molding machine as described above, the pressure is changed with time based on the output signal output from the pressure holding setting generator, and the pressure is changed in a plurality of stages. When the last stage is completed, after the last stage is completed, after the dwell completion signal is generated, it is detected whether the actual pressure is lower than the set value, or whether the preset time has elapsed. The output signal is output until at least one of the conditions is satisfied, the setting of the pressure holding stage is added, the pressure control with the pressure set value being 0 is continued, and the measurement is started after the pressure control is completed.

In this case, based on the output signal output from the pressure-holding setting generator, the pressure is changed over time to perform pressure-holding at a plurality of stages.

When the pressure holding of the final stage is completed, a pressure holding completion signal is generated, and at least one of the condition of detecting that the actual pressure has become lower than the set value or the time set in advance has elapsed. The above output signal is output until the condition is satisfied, the setting of the pressure holding stage is added, and the pressure control with the pressure set value set to 0 is automatically continued. Then, the measurement is started after the pressure control ends.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram for carrying out a pressure-holding control method for an injection molding machine according to the present invention.

In the figure, a controller 1 includes a holding pressure setting generator 2 that outputs a holding pressure based on set values (pressure, time, etc.) set by a setting device (not shown) by an operator.
Is arranged. The output signal a output from the pressure-holding setting generator 2 is sent to the pressure-holding control device 3,
, And the signal e of the operation result is
And an operation signal for operating an actuator (not shown) of the molding machine.

The timer 5 starts counting in response to the pressure-holding completion signal c from the pressure-holding setting generator 2, and can switch off the switch 4 when the timer 5 counts up for a predetermined time.

Further, the comparator 6 receives a predetermined set pressure signal d signal and a pressure sensor (not shown) of the molding machine from the controller 1.
Is compared with the input pressure detection value signal b, and when the pressure detection value signal b becomes smaller than the set value, an output signal is sent to the switch 4 to turn it off.

However, this output signal is interlocked by the pressure-holding completion signal c sent from the pressure-holding setting generator 2. That is, the switch 7 is provided on the output side of the comparator 6 and the switch 7 is turned on only when the pressure-holding completion signal c is output, and only when the pressure-holding is completed, the output signal of the comparator 6 is output. Is effectively transmitted to the switch 5.

The operation of the pressure holding control method of the injection molding machine of the present invention will be described.

FIG. 2 is an operation flowchart of a pressure holding control method of the injection molding machine according to the present invention, and FIG. 3 is a view showing a table for setting each stage of the pressure holding process.

Step First, the switch 4 is turned on to perform normal pressure holding control. In this case, when the operator sets the n-th stage, the setting of the (n + 1) -th stage is added as shown in FIG.

Step When the n-th stage of the pressure holding step is completed, the pressure holding completion signal c is turned on, and the switch 7 is turned on. At this time, at the same time, the (n + 1) th stage dwell pressure setting is performed, zero pressure is output to the dwell control device 3, and dwell pressure is set to zero.

Step After that, the magnitude relationship between the set pressure signal d and the detected pressure value signal b becomes b ≦ d or waits for the timer 5 to count up (the condition is the magnitude relationship between the set pressure signal d and the detected pressure value signal b). And only one of the count-up of the timer 5 and the OR condition or the AND condition of both.

After the step condition is satisfied, switch 4 is turned off,
The holding pressure control is completed.

It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible based on the gist of the present invention, and they are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, in the pressure holding control method for an injection molding machine, the pressure is controlled with the passage of time based on the output signal output from the pressure holding setting generator. When the pressure is held at multiple stages and the pressure holding at the final stage is completed, a pressure holding completion signal is generated, and then it is detected that the actual pressure has become lower than the set value. The output signal is output until at least one of the conditions of whether or not the elapsed time elapses is added, the setting of the pressure holding stage is added, the pressure control with the pressure set value set to 0 is continued, and the pressure control ends. Weighing starts later.

In this case, after the pressure holding is completed and the pressure holding completion signal is generated, the output signal is continuously output, the setting of the pressure holding stage is added, and the pressure set value is set to 0. Then, since the pressure control is continuously performed until at least one of the conditions of detecting whether the actual pressure has become lower than the set value or elapse of a preset time is satisfied, the reproducibility is good with repetition. Decompression is performed.

Therefore, the amount of retreat of the screw at the time of pressure reduction is stabilized, and the screw position at the start of weighing can be stabilized, so that there is no variation in the quality of the molded product.

[Brief description of the drawings]

FIG. 1 is a block diagram for carrying out the method for controlling the pressure in the injection molding machine of the present invention, FIG. 2 is an operation flowchart of the method for controlling the pressure in the injection molding machine of the present invention, and FIG. FIG. 4 is a schematic view of a conventional injection molding machine showing a table for setting each stage. 1 ... Controller, 2 ... Pressure setting generator, 3 ... Pressure control device, 4,7 ... Switch, 5 ... Timer, 6 ...
Comparator.

Claims (1)

(57) [Claims] (1) Based on an output signal output from a pressure-holding setting generator, pressure is changed with time to perform pressure-holding at a plurality of stages, and (b) pressure-holding at a final stage is completed. Then, after generating the pressure-holding completion signal, the output signal is detected until it is detected that the actual pressure has become lower than the set value, or until at least one of the conditions that a preset time has elapsed is satisfied. A pressure-holding control method for an injection molding machine, wherein the pressure-holding stage setting is added to output, pressure control with a pressure set value of 0 is continued, and metering is started after the pressure control ends.