Push Switch Slider Wobble Suppression via Thermal Contraction

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Solution Overview

Problem

Existing push switches with sliders experience position deviation and wobble due to mold size errors, leading to increased mold costs and manufacturing challenges, as well as slight impact noise during the return operation.

Innovation Solution

A push switch design featuring a slider made of resin with a higher thermal contraction coefficient and lower melting temperature than the tubular case, using two shot injection molding to create contact and restriction inclined surfaces that are complementary but slightly smaller, allowing precise molding and reducing wobble and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the tubular case and slider are manufactured with high precision to suppress mold size errors, then the slider position stability is improved, but the mold cost increases

Engineering Contradiction:
Improvemold size precisionVSAvoidmold cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention changes the physical parameters of the slider material by selecting a resin with a higher thermal contraction coefficient and lower melting temperature than the tubular case material. This parameter change enables the slider to be molded slightly smaller than the complementary shape, compensating for mold size errors and achieving precise engagement without requiring high-precision molds, thus reducing manufacturing cost while maintaining position stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies local quality by making the contact portion shape similar to but slightly smaller than the restriction portion shape. This localized dimensional adjustment at the engagement interface compensates for cumulative mold size errors, ensuring precise fitting and reducing slider wobble without requiring the entire mold assembly to be manufactured with high precision.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If the contact convex portion is fitted to the restriction concave portion with complementary shapes, then the slider is held at the non-operation position, but mold size errors cause unevenness and wobble in the non-operation position

Engineering Contradiction:
Improveslider position stabilityVSAvoidengagement uniformity
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The invention applies preliminary anti-action by intentionally designing the contact portion to be slightly smaller than the complementary restriction portion shape. This pre-compensation counteracts the expected cumulative effect of mold size errors, preventing unevenness and wobble in the non-operation position before assembly occurs.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

By changing the material parameters of the slider (higher thermal contraction coefficient, lower melting temperature), the invention enables precise control of the contact portion dimensions during molding, achieving uniform engagement despite variations in mold size and eliminating slider wobble.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the slider is pushed down and returned using elastic member biasing, then the push switch operation is achieved, but slight impact noise occurs during the return operation

Engineering Contradiction:
Improvepush switch operationVSAvoidimpact noise
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The invention changes the material parameters of the slider to enable precise molding of the contact portion shape. This precision ensures smooth engagement with the restriction portion during return, eliminating gaps and misalignment that cause impact noise, while maintaining the elastic member biasing operation.

Inventive Principle:
Principle #35Parameter changes

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

The design effectively suppresses slider wobble and position deviation, reduces mold costs, and minimizes impact noise during the return operation by ensuring precise engagement of inclined surfaces, enabling low-cost, high-precision manufacturing.

Implementation Method 1

the slider is a mold made of a resin material having a higher thermal contraction coefficient and a lower melting temperature than those of the resin material of the tubular case

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP2139014B1Push switch and method of manufacturing the same
Publication Date: 2014.09.17 ALPS ALPINE CO LTD
  • EP2139014B1 patent drawingFigure 1
  • EP2139014B1 patent drawingFigure 2
  • EP2139014B1 patent drawingFigure 3~4

AI summary

Provided are a push switch capable of effectively suppressing a position deviation or a wobble of a slider caused by errors of mold sizes as well as reducing mold cost, and a method of manufacturing the same. The push switch includes a slider (3) which is supported by a tubular case (2) to reciprocate and is pushed to be operated. Contact inclined surfaces (33a to 36a) of contact convex portions (33 to 36) of the slider (3) come in contact with restriction inclined surfaces (22a to 25a) of restriction concave portions (22 to 25) of the tubular case (2), respectively, the slider (3) upon retreating is returned to a predetermined non-operation position. In addition, the slider (3) is molded by injection-molding a resin material having a higher thermal contraction coefficient and a lower melting temperature than the resin material of the tubular case (2) in a cavity using the tubular case (2) as a part of a mold. Therefore, each contact convex portion has a shape similar to and slightly smaller than a convex portion complementary to the respective restriction concave portion. An interval between the restriction inclined surfaces (22a and 23a) increases in a retreat direction and also increases in an inward direction of the restriction concave portions (22 and 23), which is substantially perpendicular to the retreat direction.