JP3544679B2 - Eject control method for electric injection molding machine - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an ejection control method in an ejection step of an electric injection molding machine.
[0002]
[Prior art]
Conventionally, in an electric injection molding machine having a mold opening / closing eject mechanism for opening / closing a mold via a crank mechanism and a toggle mechanism by a servomotor, the ejection stroke of the mold opening / closing eject mechanism has characteristics as shown in FIG. The torque of the servomotor during the eject operation in the section and the mold clamping operation in the mold stroke section is controlled. In this case, from the mold opening / closing eject mechanism, an ejection force represented by a characteristic F and a mold clamping force represented by a characteristic G are obtained as shown in FIG.
[0003]
In FIG. 4, A is an ejecting position which is an end point at the time of ejection, B is a mold opening position which is a starting point of mold clamping, C is a mold protection function start position which is a starting point of a mold protection section, and D is a mold. A mold touch position, which is a fitting point of the upper mold and the lower mold, is a lock-up position, which is a tightening point of the mold.
[0004]
Here, the eject control method is shown as a control method in an eject stroke section (between AB) in FIGS. 4A and 4B.
[0005]
[Problems to be solved by the invention]
In such a control method, as shown in FIG. 4B, as the stroke of the mold opening / closing eject mechanism approaches the ejecting position A in the eject stroke section, the ejecting force of the mold opening / closing eject mechanism becomes extremely large, There is a problem that a large load is applied to the mold and the frame holding the mold during the eject operation, and the mold and the frame are damaged.
[0006]
SUMMARY OF THE INVENTION It is an object of the present invention to provide an eject control method for an electric injection molding machine in which a large load is not applied to a mold, a frame, and the like in an eject stroke section, and these can be prevented from being damaged.
[0007]
[Means for Solving the Problems]
Ejection control method for an electric injection molding machine of the present invention, when ejecting the molded article in the mold closing ejection mechanism for opening and closing the mold with a servo motor, so that a constant ejection force obtained in accordance with the change of the eject stroke One is selected from a plurality of preset torque curves according to the molded article, and the torque of the servomotor is controlled according to the selected torque curve .
[0008]
[Action]
According to the present invention , a constant ejecting force is obtained from the mold opening / closing eject mechanism by changing the torque of the servomotor in accordance with the eject stroke detected by the position detector.
[0009]
【Example】
Hereinafter, an embodiment of an eject control method for an electric injection molding machine according to the present invention will be described with reference to FIGS. Note that the same components as those in FIG. 4 illustrating the conventional control method are denoted by the same reference numerals.
[0010]
One example of the electric injection molding machine is configured as shown in FIG. A mold opening / closing eject mechanism 5 including a crank mechanism 3 for changing the rotational motion transmitted from the servomotor 1 of the power source via the belt 2 to a horizontal reciprocating motion, and a toggle mechanism 4 for converting the horizontal reciprocating motion to a vertical reciprocating motion; A control unit 7 attached to the servomotor 1 for controlling the torque of the servomotor 1 based on the output of a position detector 6 for detecting a vertical stroke of the mold opening / closing eject mechanism 5, and a guide connected to the mold opening / closing eject mechanism 5. A mold comprising a lower mold 10a attached to a movable plate 9 slidable along 8 and an upper mold 10b attached to a frame 11 via a fixed plate 12 and provided with a nozzle 13 for injecting a molding material. And 10.
[0011]
The steps of the molding operation according to the above configuration will be described below. The movable platen 9 is raised from the position B to the position E, and the lower mold 10a and the upper mold 10b are fitted to each other. In this state, a molding material is injected from the nozzle 13 into the inside of the mold 10, and a molded product is formed. Is formed, the movable platen 9 is lowered to the position A, the molded product held by the lower mold 10a is ejected to the outside of the mold 10 and taken out, and finally the movable platen 9 is returned to the position B. Complete the molding operation.
[0012]
In the above configuration, characteristics L to Q as shown in FIG. 2 obtained by changing the force parameters in the calculation relating to the toggle / crank mechanism are written in the control unit 7. The torque of the servomotor 1 is controlled as follows based on the molding conditions set as .about.Q. The control unit 7 selects an appropriate torque characteristic according to the eject stroke (distance between AB) and the mold clamping stroke (distance between BE) set as molding conditions from the characteristics L to Q. The servo motor 1 is controlled based on the characteristics. In FIG. 2, -30 to 0 [mm] on the horizontal axis is the section of the eject stroke, and 0 to 100 [mm] is the section of the mold clamping stroke. In this case, as shown in FIG. 3, from the mold opening / closing eject mechanism 5, an ejecting force H and a mold clamping force I, which are constant values in each section, are obtained.
[0013]
Here, the eject control method is shown as a control method in an eject stroke section (between AB) in FIGS.
With the above configuration, a constant ejecting force can be obtained from the mold opening / closing eject mechanism 5 during the eject operation in the eject stroke section. Therefore, the load on the mold 10 and the frame 11 due to an incorrect setting of the ejection stroke of the molding conditions can be reduced, and damage to the mold 10 and the frame 11 can be prevented. Further, by changing the parameters of the calculation force of the toggle-crank mechanism, the control characteristics of the servomotor 1 can be freely selected over a wide range of molding conditions, and eject control with higher accuracy can be performed.
[0014]
【The invention's effect】
As described above, according to the present invention, when ejecting a molded product, the control characteristics of the servomotor can be freely selected from a plurality of preset torque curves according to the molded product over a wide range of molding conditions. , by changing the torque of the servo motor in accordance with the position of the eject stroke in accordance with the torque curve, Ru can be the ejection force of the mold opening and closing eject mechanism or et constant.
Therefore, high-precision eject control can be performed for various molded products over a wide range of molding conditions, preventing breakage of molded products due to inappropriate torque control at the time of ejecting, and controlling the eject stroke as a molding condition. It is possible to reduce a load on a mold, a frame, and the like due to an excessive ejecting force which has conventionally occurred due to a setting error.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of an electric injection molding machine. FIG. 2 is a control characteristic diagram of an embodiment of an eject control method of the electric injection molding machine of the present invention. FIG. 3 is an output characteristic diagram of the embodiment. FIG. 4 is a control characteristic diagram and an output characteristic diagram of a conventional eject control method.
1 servo motor 5 type opening / closing eject mechanism 6 position detector

Claims (1)

Upon to eject the molded article in the mold closing ejection mechanism for opening and closing the mold with servo motors, combined from a plurality of torque curves is preset to a constant ejection force obtained in accordance with the change of the eject stroke moldings select one Te, ejection control method for an electric injection molding machine that controls the torque of the servo motor in accordance with the selected torque curve.

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