Method for controlling injection speed of screw of injection molding machine

Abstract

The invention discloses a method for controlling the injection speed of a screw of an injection molding machine, which comprises following steps of: (1) carrying out phase-step open-loop test on an injection process, (2) carrying out displacement segmentation on a displacement area of the screw, (3) confirming the set value of an identification signal, recording measured values of the identification signal, injection speed data and displacement data of the screw in the whole identification test at different moments, (4) confirming time segmentation data corresponding to the identification test, then modeling and segmenting to identify linear model of each partial model segmentation span, (5) establishing global nonlinear model which takes screw injection displacement as scheduling variable, (6) measuring injection displacement of the screw on line to linearize the global nonlinear model to obtain a linear model, and (7) taking the linear model as a prediction model of a dynamic matrixmodel prediction controller to carry out closed-loop control on the screw injection speed. By adopting the invention, the nonlinear model can be linearized conveniently, and the set point of the injection speed can be tracked effectively. The modeling process is simple and the identification cost is low.

Description

technical field [0001] The invention belongs to the technical field of injection molding engineering, and in particular relates to a screw speed control method in the injection process. Background technique [0002] Injection molding is an important technology in the polymer processing industry. This process can cost-effectively produce many plastic products. These products have a wide range of applications in industry, agriculture, electronics and household. An injection molding machine usually includes an injection unit, a switch mold unit, a hydraulic power unit, and a control unit. [0003] Plastic polymers are melted, heated and stirred in the injection unit. The molten polymer is then extruded under injection pressure into the mold cavity belonging to the switch mold unit. Upon cooling, the molten polymer solidifies into an article having the shape of the mold cavity. The hydraulic power unit is used to control the injection unit, and the control unit is responsible...

AI Technical Summary

Problems solved by technology

[0026] In view of the non-linear and time-varying characteristics of the injection speed in the injection process of the current injection molding machine, and the existing control method cannot well realize the effective control of the injection speed of the injection molding machine, the technical problem to be solved by the present invention is to provide an injection molding machine Machine screw injection speed control method, which realizes effective tracking of the set value of screw injection speed

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