Friction-Reducing Bell Cup Surface for Effect Paint Application

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Solution Overview

Problem

Conventional rotary atomizers cause damage to effect paints' light-reflecting particles due to high frictional and shearing forces during film formation, leading to color deviations and surface defects, necessitating manual touch-ups and additional material efforts for color matching and repair paints with limited shelf life.

Innovation Solution

A bell cup with a friction-reducing surface layer on the overflow surface, featuring a surface roughness less than the paint film thickness and a texture such as riblet or sharkskin structure, reduces boundary surface friction, preventing damage to effect particles and allowing for efficient automatic application of effect paints without the need for specific paint formulations or increased air consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-speed rotary atomization is used to apply effect paints, then productivity is improved, but effect particles are damaged due to high frictional and shearing forces

Engineering Contradiction:
Improvepainting speedVSAvoidparticle damage
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

A friction-reducing surface layer is introduced as an intermediary between the paint film and the bell cup surface. This layer mediates the interaction by reducing frictional and shearing forces, allowing high-speed rotation without damaging effect particles. The surface layer acts as a protective interface that enables fast atomization while preserving particle integrity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional bell cups are used for effect paints, then manufacturing simplicity is maintained, but color consistency deteriorates due to particle damage

Engineering Contradiction:
Improvebell cup fabricationVSAvoidcolor consistency
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

Instead of changing the entire bell cup structure, only the local surface quality is modified by applying a friction-reducing coating to the overflow surface. This localized modification preserves the overall simplicity of bell cup manufacturing while specifically addressing the color consistency issue by reducing particle damage at the critical paint flow interface.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If paint formulation is adapted to compensate for particle damage, then color matching is improved, but material costs and organizational effort increase

Engineering Contradiction:
Improvecolor matchingVSAvoidpaint formulation complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of adapting the paint formulation to compensate for damage caused by the atomization process, the approach is inverted: the atomization surface is modified to reduce damage in the first place. By reducing frictional forces through the friction-reducing surface layer, particles remain intact, and standard paint formulations can be used without complex corrections.

Inventive Principle:
Principle #13The other way round (Inversion)

4Manufacturing precision

If manual touch-up is used to repair surface defects, then surface quality is improved, but productivity decreases due to mixed operation requirements

Engineering Contradiction:
Improvesurface qualityVSAvoidpainting line efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The friction-reducing surface layer provides beforehand protection against particle damage during automatic painting. By preventing damage in advance through the protective surface layer, the need for subsequent manual touch-up operations is eliminated, allowing continuous automatic painting without interruptions for repairs.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 solution enables the application of effect paints with reduced particle damage, maintaining color consistency and efficiency, eliminating the need for manual touch-ups and costly paint corrections, while extending the service life of the atomizer by reducing abrasion.

Implementation Method 1

reduces the boundary surface friction between a paint film (10) on the overflow surface (8) and the overflow surface (8) itself

Methodology Applied
Scientific EffectFriction reduction: Friction

Implementation Method 2

a texture such as riblet or sharkskin structure, reduces boundary surface friction

Methodology Applied
Scientific EffectRiblet structure friction reduction: Drag

Implementation Method 3

flows on the bell plate via an overflow surface to an outer and annular spray edge, where the paint is thrown off by centrifugal force

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP2015873B1Application element for a rotary sprayer and associated operating method
Publication Date: 2011.07.27 DUERR SYSTEMS GMBH
  • EP2015873B1 patent drawingFigure 1~2

AI summary

The invention relates to an application element (1) for a rotary sprayer, in particular in the form of a bell-shaped plate or a rotary disc, with an overflow surface (8) which, during the coating operation, rotates together with the application element (1) and is overflowed by a coating agent to be applied, and with a surface layer which is located on the overflow surface (8) and on which a thin coating agent film forms with a certain film thickness during operation, wherein boundary surface friction acts between the coating agent film and the surface layer. It is proposed that the surface layer reduces the boundary surface friction between the coating agent film and the overflow surface (8). Furthermore, the invention comprises an associated operating method.