Insert-Molded Pipe Joint Sealing With Retaining Pin Cooling
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Solution Overview
Problem
In pipe joint manufacturing via insert molding, the seal member can deform and form gaps with the retaining pin due to heating, leading to reduced sealing performance as excess resin adheres to the inner peripheral face.
Innovation Solution
A method and mold design where the seal member is cooled through a retaining pin with a cooling channel, ensuring the molten resin flows into the mold in a way that suppresses deformation and gap formation by positioning the mold face on a straight line with the inflow direction, maintaining the seal member's integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the mold is heated (pre-heated) prior to filling molten resin, then the mold temperature is improved for resin filling, but the seal member becomes soft and deforms causing gap formation
Solution Approach 1:
The mold is divided into two separate temperature control zones: the accommodating area where the seal member is placed is kept at a lower temperature to maintain seal member rigidity, while the hollow area for molding the housing is heated to appropriate temperature for resin filling. This spatial segmentation of temperature control allows both requirements to be satisfied simultaneously.
Solution Approach 2:
Different regions of the mold are assigned different thermal properties and temperature levels. The accommodating area maintains low temperature to prevent seal member softening, while the hollow area is heated for optimal resin flow and filling. This local differentiation of thermal conditions resolves the contradiction between mold heating and seal member stability.
2Productivity
If molten resin flows directly onto the seal member, then the housing is molded efficiently, but the seal member deforms and gaps form reducing sealing performance
Solution Approach 1:
The seal member is pre-cooled in the accommodating area before the molten resin is introduced into the hollow area. This preliminary cooling action ensures the seal member maintains its shape and rigidity during the subsequent resin filling process, preventing deformation and gap formation while allowing efficient molding to proceed.
Solution Approach 2:
The accommodating area acts as an intermediary zone that isolates the seal member from direct contact with molten resin. By maintaining a temperature gradient between the accommodating area and the hollow area, the seal member is protected from thermal softening and direct resin impact, ensuring sealing performance is maintained while housing molding proceeds efficiently.
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 approach effectively prevents gap formation between the seal member and retaining pin, enhancing the sealing performance and productivity by maintaining the seal member's shape and reducing excess resin adherence.
Implementation Method 1
the seal member is cooled through the retaining pin
Implementation Method 2
causing a molten resin to flow into the mold
Data Source
AI summary
A manufacturing method for manufacturing a pipe joint including a circular tube-shaped housing and an elastically deformable circular tube-shaped seal member provided at an inner peripheral side of the housing. The pipe joint manufacturing method includes a process of placing the seal member inside a mold in a state in which the seal member is fitted to an outer periphery of a retaining pin, and a process of causing a molten resin to flow into the mold so as to mold the housing in a state in which the seal member is cooled through the retaining pin.