Sanding Device Self-Centering Crown Gear Coupling

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Solution Overview

Problem

Existing sanding devices with pin-hole connections face safety hazards due to unguarded rotating pins and require significant user effort for precise alignment, especially with flexible connecting legs that bias the connection.

Innovation Solution

A sanding device with a self-centering, clearance-free coupling using crown gears with toothing, where the first coupling part connected to the drive shaft and the second coupling part on the workpiece processing part engage as crown gears, clamped by clamping means to ensure precise alignment and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If pin-hole connection is used for coupling drive shaft to workpiece processing part, then the coupling structure is simple, but it creates safety hazards due to unguarded rotating pins and requires significant user effort for precise alignment

Engineering Contradiction:
Improvecoupling structureVSAvoidsafety hazards from rotating pins
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and eliminates the hazardous pin elements from the coupling mechanism. Instead of using exposed rotating pins that create safety hazards, the patent employs a enclosed coupling mechanism where the drive shaft connects to the workpiece processing part through a housing that contains all coupling elements, removing the source of injury risk while maintaining the simplicity of the coupling structure

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces an intermediary coupling mechanism between the drive shaft and workpiece processing part. This intermediary system uses a driven gear on the drive shaft that engages with a crown gear on the workpiece processing part, mediated by a housing and clamping mechanism. This intermediary structure eliminates direct pin connections while maintaining efficient power transmission and precise alignment

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If pin-hole connection with clearance is used, then the coupling allows for oscillating movements, but the clearance increases with use and requires significant effort for initial alignment

Engineering Contradiction:
Improveoscillating movement capabilityVSAvoidalignment time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The invention applies preliminary action through self-centering features built into the coupling mechanism. The driven gear and crown gear are designed with geometric features that automatically guide and center the components during engagement, eliminating the need for manual alignment. The clamping mechanism also applies pre-load to maintain consistent engagement without increasing clearance over time

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention employs dynamic coupling characteristics where the gear engagement allows for controlled oscillating movements while maintaining constant mesh contact. The clamping mechanism provides adjustable pressure to accommodate thermal expansion and wear, maintaining precise alignment dynamically throughout operation rather than relying on fixed clearance

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If flexible connecting legs are used to pre-align the connection, then the coupling accommodates positional variations, but the alignment process becomes more difficult and time-consuming

Engineering Contradiction:
Improvepositional adaptationVSAvoidalignment ease
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The invention uses asymmetric gear tooth profiles and engagement geometries that provide natural guidance during coupling. The driven gear and crown gear are designed with asymmetric features that guide the workpiece processing part into correct alignment automatically during the engagement process, eliminating the need for flexible connecting legs or manual pre-alignment while maintaining adaptability to positional variations

Inventive Principle:
Principle #4Asymmetry

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 provides a safer and more efficient coupling mechanism that eliminates the risk of injury from rotating pins and simplifies the alignment process, allowing for precise and secure engagement of the workpiece processing parts.

Implementation Method 1

the toothing of the first coupling part and the toothing of the second coupling part are mutually engageable crown gears

Methodology Applied
Scientific EffectGear mechanism: Gear

Implementation Method 2

first clamping means which are configured to clamp the crown gears of the first and the second coupling part in engaging contact against each other

Methodology Applied
Scientific EffectMechanical clamping: Mechanical Force

Data Source

PatentEP3791999B1Sanding device
Publication Date: 2025.02.12 NANJING CHERVON IND
  • EP3791999B1 patent drawingFigure 1
  • EP3791999B1 patent drawingFigure 2
  • EP3791999B1 patent drawingFigure 3

AI summary

The present invention relates to a device(1) for processing a workpiece, comprising a housing (2), a drive arranged in the housing for driving a drive shaft (4) relative to the housing, a first coupling part (6) connected directly or indirectly to the drive shaft and provided with a toothing (8), and a first workpiece processing part (109 which is provided with a second coupling part (12) connectable in engaging manner to the first coupling part (6), and wherein the second coupling part (12) is provided for this purpose with a toothing (14) co-acting with the toothing (8) of the first coupling part (6), wherein the toothing (89 of the first coupling part (6) and the toothing (14) of the second coupling part (12) are mutually engageable crown gears, and wherein the device further comprises first clamping means (16) which are configured to clamp the crown gears (8, 14) of the first and the second coupling part (6, 12) in engaging contact against each other and to thus form a self-centering clearance-free coupling.