Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting
Patent
1991-11-04
1993-10-26
Heitbrink, Jill L.
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
264 405, 425140, 425145, 425150, B29C 4577
Patent
active
052563456
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an injection control method for controlling the weight of the plasticized synthetic resin injected from a cylinder of an injection molder to fill a cavity of the mold.
BACKGROUND OF THE INVENTION
In the conventional injection molding of plasticized synthetic resin by an injection molder, the weight of the injected plasticized synthetic resin varies with the molten resin pressure, the molten resin specific volume or the molten resin temperature (including the influence of the disturbance on the molding system) etc.. Therefore, it is difficult to form products of a constant quality. To cope with this problem, so-called adaptive control a number of proposals have been made. The art disclosed in the Japanese Patent Laid Open Publication No. 84932 of Showa 56 (the year 1981) is an example.
Basically, in the adaptive control method, when the influence of a disturbance on the molding system and change in the molten resin pressure, molten resin temperature or mold temperature are detected, a controllable molding condition (pressure, time, etc.) other than the detected factors, are changed into a control factor, thereby assuring the constant product quality.
However, this control method has the following problems: between the detected factor according to the mold and the product quality and between the control factor and the product quality. detected factor and the product quality and between the control factor and the product quality varies greatly depending on the mold. Therefore, the study and analysis described in the item 1 above must be repeated each time the mold is changed.
In order to solve aforementioned problems, the present invention provides an injection control method of an injection molder, which assures the products of constant quality even when there is an influence to the molding system by the disorder from outside, there is a change in the given condition such as the change of the molten resin pressure and which does not require the analysis and the investigation from the beginning as in a case of the adaptive control method even the cavity is changed. the cavity is changed, and offers a molder products of of constant quality.
DISCLOSURE OF THE INVENTION
According to the present invention, in order to achieve the aforementioned object, an injection control method for controlling the weight of the plasticized synthetic resin injected from the cylinder of an injection molder to fill the cavity of a mold comprises the steps of: calculating the travel distance S.sub.D of the screw to the position for injecting plasticized synthetic resin by the amount corresponding to the weight value G of a product by using a specified calculation formula and preset it, on the basis of the weight value G of the product, and terminating the injection of the plasticized synthetic resin into the cavity when the screw has moved for the preset travel distance S.sub.D from the stop position immediately before injection.
Further, the calculation by using the specified formula for obtaining the travel distance S.sub.D of the screw to the position for injecting the plasticized synthetic resin by the amount corresponding to said weight value G of a product is carried out at a constant molten resin temperature value T, on the basis of the detected or set molten resin pressure value P.sub.I of plasticized synthetic resin immediately before injection, the detected or set molten resin pressure value P.sub.H of plasticized synthetic resin during the dwelling process following the injection, the detected positional value S.sub.I of the screw immediately before injection, and the PV property relation formula of plasticized synthetic resin, as follows: .multidot.[1/V(P.sub.I)-1/V(P.sub.H)]} following the injection. process following the injection injection.
Or, the calculation by using the specified formula for obtaining the travel distance S.sub.D of the screw to the position for injecting the plasticized synthetic resin by the amount corresponding to said weight value G
REFERENCES:
patent: 3750134 (1973-07-01), Weisend
patent: 3859400 (1975-01-01), Ma
patent: 3932083 (1976-01-01), Boettner
patent: 4816197 (1989-03-01), Nunn
Dominick V. Rosato et al., Injection Molding Handbook, 1986, pp. 98-102.
Heitbrink Jill L.
Komatsu Ltd.
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