Chamfered Positioning Pin Structure for Accurate Resin Fitting

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Solution Overview

Problem

In resin molded products with inclined positioning pins, the formation of undercuts during injection molding leads to parting lines on the outer surface, which can reduce the positional accuracy of fitting when these pins come into contact with other components.

Innovation Solution

The resin molded product incorporates chamfered portions on the outer peripheral surface of the positioning pin, where the parting line is formed, preventing it from contacting other fitting members and maintaining positional accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an undercut process is performed using a slide core to enable molding when the axial direction of the positioning pin is inclined with respect to the removal direction of the core, then molding can be performed, but a parting line is generated on the outer peripheral surface of the positioning pin at the joint between the core and slide core, resulting in a decrease in positional accuracy of fitting

Engineering Contradiction:

ImprovemoldabilityVSAvoidpositional accuracy of fitting

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The harmful parting line is extracted from the outer peripheral surface by forming it on the end surface instead. The slide core joint is repositioned to create the parting line on the end surface of the positioning pin, which is then removed during machining of the fitting hole, eliminating the harmful effect on fitting accuracy

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The end surface of the positioning pin serves as an intermediary location for the parting line. By placing the parting line on this intermediate surface rather than the outer peripheral surface, the harmful effect is transferred to a location that can be subsequently removed without affecting fitting accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the axial direction of the positioning pin is inclined with respect to the removal direction of the core, then design flexibility is improved, but an undercut occurs that cannot be molded using just the cavity and core

Engineering Contradiction:

Improvedesign flexibilityVSAvoidmoldability

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The mold structure is made dynamic by incorporating a slide core that can move relative to the main core. This allows the mold to adapt to the inclined positioning pin geometry during molding, enabling production of pins with axial directions inclined at various angles while maintaining ease of manufacture

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20250065720A1Resin molded product and in-vehicle information device

Publication Date: 2025.02.27 DENSO TEN LTD

AI summary

A resin molded product includes: a first surface; and a first positioning pin extending from the first surface in a first direction. The first positioning pin includes chamfered portions chamfered at two positions facing each other on an outer peripheral surface of the first positioning pin when viewed from the first direction, and a parting line is formed in the chamfered portions.