Insert Molded Article Manufacturing Method
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Solution Overview
Problem
The existing methods for manufacturing resin gears with metallic cores using dedicated two-color molding machines are costly, less versatile, and prone to deformation due to mold shrinkage, making it difficult to stabilize mass production quality and yield.
Innovation Solution
A manufacturing method utilizing two general injection molding machines with a common insert core for primary and secondary molding, which suppresses deformation and simplifies die fabrication, allowing for efficient production of resin gears with metallic cores without specialized equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dedicated two-color molding machine is used for primary and secondary molding, then product quality stability is improved, but introduction cost increases and versatility decreases
Solution Approach 1:
The patent applies universality by using a common insert core for both primary and secondary molding processes on general-purpose injection molding machines. The insert core serves multiple functions: it acts as the metallic core during primary molding to form the inside member, and then serves as a positioning fixture during secondary molding to form the outside member. This multi-functional use of the insert core eliminates the need for specialized two-color molding machines while maintaining quality stability.
2Manufacturing precision
If a dedicated two-color molding machine is used for primary and secondary molding, then product quality stability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the essential function from complex dedicated two-color molding machines - the use of a common insert core for positioning - and applies it separately on general-purpose injection molding machines. By separating the molding processes into two independent steps using the same insert core, the system eliminates the need for complex dedicated machinery with multiple dies and rotation mechanisms, significantly reducing device complexity while maintaining positioning accuracy.
3Productivity
If the primary molded article is removed from the die after primary molding, then the insert core can be reused for secondary molding, but deformation occurs due to mold shrinkage
Solution Approach 1:
The patent introduces the insert core as an intermediary element that remains in the die during primary molding to form the inside member, then the inside member is removed while the insert core stays. The insert core serves as a mediator between the two molding processes - it provides positioning reference for the outside member during secondary molding, compensating for any dimensional changes in the inside member due to shrinkage. This intermediary role of the insert core ensures dimensional accuracy is maintained despite the removal and reuse cycle.
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 method reduces production costs, enhances versatility, stabilizes mass production quality, and improves yield by preventing deformation and sink marks, while allowing for weight reduction and shorter molding cycles.
Implementation Method 1
fitting the insert core (7) into the insert (2) to obtain a coupled body (10) in which the insert (2) and the insert core (7) are coupled
Implementation Method 2
injecting a molten resin for primary molding into a cavity of the primary molding die for injection molding of the inside member
Implementation Method 3
injecting a molten resin for secondary molding into a cavity of the secondary molding die for injection molding of the outside member
Implementation Method 4
the annular metallic sleeve and thinned portions of the resin part formed for weight reduction are deformed under influence of mold shrinkage or the like to change the dimensions of the primary molded article
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(c)
AI summary
The present invention is intended to provide a manufacturing method of an insert molded article that makes it possible to manufacture efficiently the insert molded article including a metallic insert, an inside member made of a synthetic resin and covering a portion of the insert, and an outside member made of a synthetic resin different from the material of the inside member and covering a portion of the inside member using general molding machines, not a dedicated two-color molding machine. General molding machines are used to manufacture the insert molded article formed by injection molding of a resin part in twice. An insert core 7 is used in common in primary molding using a primary molding die C1 and in a secondary molding using a secondary molding die. Around shaft 7C of the insert core 7 is fitted into an internal hole 2C of an insert 2 to form a coupled body 10 in which the insert 2 and the insert core 7 are coupled together. The coupled body 10 is used in common at the primary molding step and the secondary molding step