Abstract:

In view of the difficulties in the design of the forming mold for the vane plastic part of the micro centrifugal pump, an improved three?plate point?gate mold was designed for the forming of the vane plastic part of the pump. In order to control the deformation of the plastic part, a three?point gate was adopted to balance the injection molding. The mold cavity was arranged in one mold and one cavity. In view of the difficulty of demolding in the groove area of plastic parts, a three?layer and three?time composite core pulling demolding system was designed to demold the characteristic module of the groove part. In this mechanism, after the forming block with the characteristic module of the groove part was divided into two layers of forming parts, the first core pulling action of the mechanism was driven by the spring and the upper slider to implement the core pulling of the upper forming block, and then the second core pulling action of the mechanism was driven by the inclined guide pillar. Finally, the two side core pulling sliders were driven by the base slide block driven by the bending pin to pull out the core so as to make the moving space of the plastic part completely ejected from the demolding. The driving forces of the second core pulling and the third core pulling were driven by the third and fourth mold opening of the mold base template, respectively. The final demolding of the plastic part was realized by the cylinder driving the ejector pin plate and the ejector rod. Based on the action needs of the plastic part, runner demolding and core pulling mechanism, the typical three?plate point?gate mold base was modified to a four?plate four?time opening point gate. In this case, the core pulling demolding could be carried out by the plastic part, runner waste and driving slider mechanism in sequence. The action setting of mold demolding mechanism is found to be reasonable, the design of mechanism structure is ingenious, and the overall work of mold is reliable, which can become a good reference for mold design.

Key words: multi layer core pulling, three plate mold, structure improvement, mechanism design, injection mold