A micro-injection molding device and method based on dynamic control of cavity air pressure

Abstract

The invention discloses a cavity gas pressure dynamic control-based micro injection molding apparatus and a method thereof. The apparatus comprises a movable die and a static die, the middle of the movable die is provided with a movable die insert, the middle of the static die is provided with a static die insert, the static die insert and the movable die insert are respectively provided with die insert cavities, the static die insert is arranged in the die insert cavity of the static die insert, a die core inner gas cavity is arranged in every die insert, the movable die core inner gas cavity is connected with a movable die inner gas cavity, the movable die gas cavity opening of the movable die inner gas cavity and the static die gas cavity opening of the static die inner gas cavity are respectively connected with gas pumps through pipelines provided with solenoid valves, and the gas pumps are connected with the control system of an injection molding machine used for installing the movable die and the static die. The apparatus and the method promote the filling quality of a polymer melt, and also promote the demolding effect.

Description

technical field [0001] The invention relates to a polymer micro-injection molding device and method, in particular to a micro-injection molding processing device and method that can be used for high aspect ratio polymer material microstructure devices. Background technique [0002] With the development of micro-nano technology, micro-components are widely used in biomedicine, electronic communication, aerospace and other fields. At present, there are various methods for processing micro-components, but most of the micro-processing methods still have many defects, such as complex processing technology, difficulty in repeated mass production, low efficiency, high cost, etc., which seriously limit the development of micro-nano technology. [0003] In order to solve the shortcomings of the existing micro-processing methods, micro-injection molding technology came into being. Micro-injection molding technology, as a manufacturing technology that can carry out repeated batch prod...

AI Technical Summary

Problems solved by technology

However, the micro-injection molding technology at this stage is not mature, and the traditional conventional injection molding theory and technology are no longer applicable to micro-injection molding

The isothermal filling conditions of traditional injection molding technology are not suitable for micro-injection molding: as the cavity decreases, the surface area to volume ratio of the polymer melt increases rapidly, while the heat it carries decreases relatively, and the melt temperature decreases rapidly, resulting in The viscosity of the polymer melt in the micro-cavity of the mold increases rapidly, which reduces the flow properties of the polymer melt and affects the filling quality; at the same time, the condensation layer formed when the melt contacts the cavity will further hinder the filling

Especially in the case of injection molding high aspect ratio plastic parts, the impact of micro-cavity is particularly serious. High aspect ratio structural cavity is likely to cause structural exhaust difficulties, and trapped air is easy to occur in the cavity, which hinders the flow of polymer melt. The further flow in the cavity increases the pressure in the cavity, resulting in insufficient filling of the mold, which affects the shape reproduction accuracy of the product

Moreover, for plastic parts with high aspect ratio, when entering the demoulding stage after injection, pressure holding and cooling stages, due to the high surface area to volume ratio of plastic parts with high aspect ratio, it is easier to produce large Therefore, it is more difficult to demould plastic parts with high aspect ratio; at the same time, plastic parts molded with high aspect ratio have the characteristics of "thin and long", and the tensile strength of plastic parts is relatively weak, which is prone to plastic parts during demoulding. In the case of being pulled off, not only the integrity of the plastic part is destroyed, the broken plastic part blocks the cavity of the mold core, and even destroys the entire mold core in severe cases

[0004] At present, researchers and practitioners from various countries have carried out a large number of theoretical studies and technological attempts, starting from the injection molding process and injection molding method to improve the injection molding quality of high aspect ratio microstructure plastic parts. The methods of process parameters such as temperature, polymer melt temperature, injection speed and injection pressure can improve the quality of mold filling; in terms of injection molding methods, heating assistance, hot runner, ultrasonic assisted micro-injection molding methods, etc. have been proposed, and these efforts have improved to a certain extent. The filling quality of injection molding with high aspect ratio is improved, but in order to achieve the effect, special requirements are put forward for the injection molding equipment, which is difficult or costly to achieve, and it has not fundamentally solved the impact of trapped air in the cavity on the filling process. Does not involve the improvement of the demoulding quality of plastic parts

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