Structured Friction Plate for Shear-Resistant Painted Joints

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Solution Overview

Problem

Existing screw connections between lacquer-coated components face low shear strength due to low static friction coefficients, necessitating expensive friction-enhancing inserts like nonwoven fabrics or diamond-dust-coated washers.

Innovation Solution

A friction plate with integrated surface structure is used between lacquer-coated components, enhancing the coefficient of friction by conforming to the lacquer layer's irregularities, eliminating the need for special coatings on bare metal surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If smooth painted surfaces are used for lacquer-coated components, then the manufacturing process is simple and cost-effective, but the static friction coefficient is low (μH ≈ 0.1) resulting in insufficient shear strength

Engineering Contradiction:

Improveshear strength of screw connectionVSAvoidmanufacturing complexity of friction-enhancing solution

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

A friction plate is introduced as an intermediary element between the two lacquer-coated components. This friction plate has a specifically structured surface that increases the coefficient of friction, thereby enhancing the shear strength of the screw connection without requiring modification of the original components. The friction plate mediates the interaction between the smooth painted surfaces, providing the necessary friction while keeping the manufacturing process simple.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The surface properties of the friction plate are specifically designed with a roughness profile that optimizes the coefficient of friction. By changing the surface parameters (roughness, texture) of the friction plate rather than the base components, the solution achieves high friction values (μH up to 0.4) while maintaining ease of manufacture. The friction plate can be produced cost-effectively through conventional surface treatment methods.

Inventive Principle:

Principle #35Parameter changes

2Strength

If expensive friction-enhancing inserts such as nonwoven fabrics coated with adhesive particles or diamond-dust-coated metal washers are used, then the shear strength is improved, but the manufacturing cost increases significantly

Engineering Contradiction:

Improveshear strength of screw connectionVSAvoidcost of friction-enhancing materials

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

The friction plate is designed as a cost-effective, simple metal washer with a structured surface, replacing expensive materials like diamond-dust coatings or adhesive-coated nonwoven fabrics. This economical friction plate achieves the necessary friction enhancement through its surface geometry alone, eliminating the need for costly special coatings or composite materials while maintaining adequate performance for the application.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Strength

If a surface structure is incorporated into the friction plate to increase friction, then the coefficient of static friction increases (up to μH 0.4), but the manufacturing precision requirements increase

Engineering Contradiction:

Improvecoefficient of static frictionVSAvoidsurface structure precision of friction plate

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The friction plate surface is structured with a roughness profile that provides sufficient friction enhancement without requiring excessive precision. The surface treatment creates a texture that is adequate for increasing the coefficient of friction to μH up to 0.4, without demanding ultra-precise manufacturing tolerances. This partial action approach achieves the necessary friction level through conventional surface treatment methods rather than requiring high-precision machining.

Inventive Principle:

Principle #16Partial or excessive 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

The shear strength of screw connections is significantly increased by fourfold, achieving a coefficient of static friction up to µH 0.4, without the need for costly materials.

Implementation Method 1

a surface structure to increase the coefficient of friction against the lacquer layer located on the two fastening sections is incorporated into the friction plate on both sides over its entire surface

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

The arrangement according to the invention takes advantage of the property of many paints that they begin to flow under increased pressure and therefore automatically conform to the irregularities formed by the surface structure of the friction plate

Methodology Applied

Scientific EffectPressure-induced flow:

Data Source

PatentEP4650608A1Arrangement for improving the shearing resistance of a threaded connection produced between components coated with paint

Publication Date: 2025.11.19 DEERE & CO

Figure 1~2

AI summary

Arrangement (10) for improving the shear strength of a screw connection produced between lacquered components (12, 14), comprising first and second lacquered components (12, 14) which, in the screwed state, comprise mutually facing planar first and second fastening sections (16, 18), and comprising a friction plate (20) extending between them, which is in planar contact with the two fastening sections (16, 18), wherein a surface structure (22) is incorporated into the friction plate (20) on both sides to increase the coefficient of friction against the lacquer layer (24, 26) located on the two fastening sections (16, 18).