Composite Plunger Structure for Injection Molding Backflow Prevention
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Solution Overview
Problem
Existing injection molding devices face challenges in preventing molten resin from flowing back between the cylinder and the plunger during the extrusion process.
Innovation Solution
The plunger is designed with a combination of metal and resin materials, featuring a smaller gap between the resin portion and the cylinder, allowing the resin portion to remain within the cylinder during the suction operation, thereby preventing backflow and reducing sliding resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plunger made of a single material is used, then the structure is simple and easy to manufacture, but it cannot effectively prevent backflow of plasticized material between the cylinder and plunger
Solution Approach 1:
The plunger is constructed as a composite structure with a resin outer layer and a metal inner core. The resin layer provides a small gap with the cylinder wall to prevent backflow, while the metal core provides structural strength and sliding properties. This composite design resolves the contradiction by combining materials with complementary properties to achieve both backflow prevention and structural integrity.
Solution Approach 2:
The plunger is divided into functionally distinct segments: a resin outer layer for sealing and backflow prevention, and a metal inner core for structural support and sliding. This segmentation allows each part to perform its specific function optimally, resolving the contradiction between preventing backflow and maintaining structural simplicity.
2Reliability
If the gap between the plunger and cylinder is reduced to prevent backflow, then backflow prevention improves, but sliding resistance increases
Solution Approach 1:
The composite plunger structure allows the resin outer layer to form a small gap with the cylinder for backflow prevention, while the metal inner core maintains structural strength and provides low-friction sliding surfaces. This resolves the contradiction by distributing the functional requirements to different material layers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively prevents backflow of plasticized material while reducing sliding resistance and facilitating easy replacement of worn parts, enhancing the maintainability and efficiency of the material supply device.
Implementation Method 1
an injection unit including a cylinder communicating with the nozzle and coupled to a flow path through which the plasticized material flows, and a plunger configured to move inside the cylinder, the injection unit being configured to perform a suction operation of suctioning the plasticized material from the flow path into the cylinder by moving the plunger rearward
Implementation Method 2
a feeding operation of feeding the plasticized material suctioned into the cylinder to the nozzle by moving the plunger forward
Data Source
AI summary
A material supply device includes: an injection unit including a cylinder communicating with a nozzle and coupled to a flow path through which a plasticized material flows, and a plunger configured to move inside the cylinder, the injection unit being configured to perform a suction operation of suctioning the plasticized material from the flow path into the cylinder by moving the plunger rearward, and a feeding operation of feeding the plasticized material suctioned into the cylinder to the nozzle by moving the plunger forward. The plunger includes, in a longitudinal direction of the plunger, at least one first portion made of a material containing metal and a second portion made of a material containing a resin, a gap between the second portion and the cylinder is smaller than a gap between the first portion and the cylinder, and in the suction operation, when the plunger moves most rearward, the second portion is located within the cylinder.