Resin Pipe Joint Molding With Gas-Discharge Cavity Gaps

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Solution Overview

Problem

Conventional resin pipe joint manufacturing methods often result in molding defects due to trapped gases within the mold cavity, leading to insufficient filling and surface roughness, and increasing filling pressure can cause appearance defects like flow marks.

Innovation Solution

A method that allows gases generated or present in the mold cavity to escape through strategically designed gaps between the mold components, ensuring complete filling of the cavity with molten resin and preventing defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If filling pressure of molten resin is increased to avoid insufficient filling, then filling completeness is improved, but appearance quality deteriorates due to flow marks

Engineering Contradiction:
Improvefilling completenessVSAvoidappearance quality
Core Design Contradiction:
Manufacturing precisionVSShape

Solution Approach 1:

The patent extracts the harmful gas from the molding system by providing dedicated discharge spaces and gas flow paths that separate gas removal from the resin filling process. This allows gas to be removed without requiring increased filling pressure, thus avoiding flow marks while ensuring complete filling.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces gas discharge spaces and flow paths as intermediary structures between the cavity and external environment. These intermediaries facilitate gas removal during injection molding, enabling complete filling at normal pressures without causing appearance defects.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If gas is trapped in the cavity during injection molding, then manufacturing simplicity is maintained, but product quality deteriorates due to molding defects

Engineering Contradiction:
Improvemolding process simplicityVSAvoidsurface quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent segments the mold cavity into functional zones by introducing discharge spaces and gas flow paths. This segmentation allows gas to be systematically removed from different regions of the cavity, preventing surface defects while maintaining a relatively simple injection molding process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary gas removal by providing pre-designed discharge spaces and flow paths before injection molding begins. This preliminary preparation ensures that gas can escape during filling without causing defects, maintaining both process simplicity and product quality.

Inventive Principle:
Principle #10Preliminary action

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 ensures favorable filling of the cavity, reducing molding defects and improving the quality of the resin pipe joint by preventing gas entrapment, thereby enhancing the joint's integrity and appearance.

Implementation Method 1

gas generated in the cavity due to the injection and/or gas (air) existing in the cavity before the supply of the molten resin can escape to a discharge space of the cavity through the gap

Methodology Applied
Scientific EffectGas flow through gap:

Data Source

PatentEP3495110B1Method for manufacturing resin pipe joint
Publication Date: 2021.03.10 NIPPON PILLAR PACKING CO LTD
  • EP3495110B1 patent drawingFigure 1
  • EP3495110B1 patent drawingFigure 2
  • EP3495110B1 patent drawingFigure 3

AI summary

A method for manufacturing a resin pipe joint with a joint body includes the following steps. Preparing a mold and a supply device (62) configured to supply molten resin. The mold includes a first mold (65) for an outer shape of the joint body and a second mold (66) for an inner shape of the joint body. Combining the second mold with the first mold to form a cavity (88), into which the molten resin is injectable, inside the mold. Supplying the molten resin to the cavity in the mold. Solidifying the molten resin in the cavity after stop of the supply of the molten resin from the supply device. The second mold has a gap (81) that connects the cavity to a discharge space outside the cavity and allows gas to flow.