Linear Motion Guide Sealing with Urethane Foam

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Solution Overview

Problem

Existing linear motion guide systems face challenges with dustproofing due to high frictional resistance from rubber-based sealing means, inadequate lubrication control, and absorption of foreign matter by foamed polyurethane components, leading to premature wear and reduced sealing performance.

Innovation Solution

A linear motion guide system featuring highly-tight sealing units composed of three-layered mechanical froth urethane foam sealing plates with a spongy texture and rubbery epidermal layers, which absorb lubricant into pores and are designed to fit snugly over guide rails, ensuring effective sealing and self-lubrication while preventing foreign matter ingress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rubber-based sealing means are used, then sealing performance is improved, but frictional resistance increases and durability decreases

Engineering Contradiction:

Improvesealing performanceVSAvoidfrictional resistance

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The patent changes the material parameters from rubber to mechanical froth urethane foam with specific physical properties (tensile strength 30-50 kg/cm³, percent elongation 300-500%, repulsion elasticity 30-60%). This material substitution reduces frictional resistance while maintaining sealing performance through the foam's unique cellular structure and elastic recovery characteristics.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes foamed polyurethane with open pores that can be impregnated with lubricant (30-50 weight %). The porous structure allows lubricant absorption and retention, providing self-lubrication that reduces frictional resistance during sliding motion while the closed-cell structure prevents foreign matter penetration, maintaining sealing performance.

Inventive Principle:

Principle #31Porous materials

2Force

If foamed polyurethane with open pores is used, then self-lubrication is improved, but foreign matter absorption increases

Engineering Contradiction:

Improvefrictional resistanceVSAvoidforeign matter absorption

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The patent employs a composite structure combining foamed polyurethane with open pores for self-lubrication and a sealing structure with foreign matter discharge capabilities. The composite system includes the foam material impregnated with lubricant plus a scraper component and sealing plate arrangement that actively removes absorbed foreign matter, transforming the harmful absorption characteristic into a manageable feature through combined material and structural design.

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If sealing means are installed on slider ends, then dustproof performance is improved, but device complexity increases

Engineering Contradiction:

Improvedustproof performanceVSAvoidsealing structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent utilizes a sealing plate made from flexible foamed polyurethane material that can be cut into the desired shape and installed in a simplified manner. The flexible nature of the foam allows it to conform to the slider end geometry and provide effective sealing without requiring complex assembly structures, reducing installation complexity while maintaining dustproof performance.

Inventive Principle:

Principle #30Flexible shells and thin films

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 system provides enhanced sealing performance, reduced frictional resistance, and effective lubrication, maintaining durability and preventing foreign matter accumulation, thus suitable for severe working environments with dust, chips, and liquids.

Implementation Method 1

The sealing plate is composed of an intermediate spongy medium flanked by skin layers of close-grained rubbery texture and fully impregnated with lubricant

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

The sealing plate is composed of three-layer structure composed of skin layers of rubbery texture to constitute epidermal layers and an intermediate medium of spongy texture

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 3

The scraper component is mounted on the slider in a way spaced away from the guide track with leaving a slight clearance between them

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS7717621B2Linear motion guide system with highly-tight sealing units

Publication Date: 2010.05.18 NIPPON THOMPSON

AI summary

A linear motion guide system is disclosed in which a clearance between a slider and a guide rail is closed truly to clear foreign matter away from entering inside the system through any end of the slider traveling on the guide rail. Thus, the linear motion guide system is befitting to severe working environment where much foreign matter occurs. A highly-tight sealing unit is provided which is comprised of a cassette constituted with a front panel and an enclosure, a sealing plate stowed into the cassette, and a rear panel to close an open edge of the enclosure. The sealing plate is composed of an intermediate spongy medium flanked by skin layers, and lubricant is forcibly absorbed in pores or cells in the intermediate layer.