Robot Joint Bearing Preload Structure for Fast Axial Bearing Assembly

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Solution Overview

Problem

Existing robots with four-bar chains for parallel and hybrid kinematics require complex and time-consuming assembly processes due to the need for precise positioning and preload adjustment of axial bearings, which increases manufacturing and maintenance complexity.

Innovation Solution

A robot with a four-bar chain featuring an elastically compressible preload element that applies axial preload force to axial bearings, allowing for precise prestressing and alignment, while simplifying the assembly process by using non-adjustable stops and symmetrically arranged link elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If clamping elements with adjustable axial position are used to apply preload to axial bearings, then precise positioning and preload adjustment are achieved, but assembly time and manufacturing complexity increase significantly

Engineering Contradiction:
Improvebearing positioning precisionVSAvoidassembly time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The link element automatically applies the predetermined axial preload force to the axial bearings through its own elastic deformation when mounted on the shaft between stops. The system self-regulates the preload without requiring external adjustment mechanisms, eliminating the need for adjustable clamping elements and significantly reducing assembly time while maintaining precise bearing positioning.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the parameter of preload application from adjustable (via movable clamping elements) to fixed and predetermined (via the elastic link element's inherent properties). The axial preload force is determined by the link element's material properties, geometry, and the distance between stops, transforming the adjustment process into a simple assembly operation.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If adjustable clamping elements are used for axial preload application, then precise bearing preload is achieved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvebearing preload precisionVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The link element serves dual functions: it transmits drive motion and simultaneously applies the predetermined axial preload to the bearings. This self-service mechanism eliminates the need for separate adjustable clamping elements, reducing device complexity while ensuring reliable and precise bearing preload through the link element's elastic properties.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The link element is designed to perform multiple functions: it acts as both the drive transmission component and the axial preload application mechanism. By integrating these functions into a single component with predetermined elastic properties, the invention reduces the number of parts and simplifies the overall device structure while maintaining precise bearing preload.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If multiple bearing points are provided in parallel kinematics for flexible movement in large workspace, then movement flexibility is improved, but the number of components and assembly complexity increase

Engineering Contradiction:
Improvemovement flexibilityVSAvoidnumber of bearing points
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Each link element in the parallel kinematics system automatically applies its own predetermined axial preload to its associated axial bearings through elastic deformation. This self-service mechanism ensures that all multiple bearing points required for flexible movement in large workspaces are automatically preloaded without requiring complex external adjustment mechanisms, reducing overall system complexity while maintaining movement flexibility.

Inventive Principle:
Principle #25Self-service

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 compact, robust, and self-centering joint bearing with reduced backlash and operational reliability, enabling flexible movement in large workspaces with reduced assembly time and maintaining precise positioning and preload force.

Implementation Method 1

an elastically compressible preloading element is provided which applies an axial preload force to the axial bearings

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3846974B1Hinge bearing for a robot comprising an elastically compressible pre-loading element
Publication Date: 2024.08.21 FRUITCORE ROBOTICS GMBH
  • EP3846974B1 patent drawingFigure 1
  • EP3846974B1 patent drawingFigure 2~3
  • EP3846974B1 patent drawingFigure 4~5

AI summary

The invention relates to a joint bearing for a robot (1), comprising a shaft (21) and at least one member element (24, 35, 36, 37, 38, 59, 60) which is rotatably mounted on the shaft (21) between two axial bearings (22, 23, 43, 44, 45, 46, 54, 55, 63, 64, 69), wherein an elastically compressible pre-tensioning element (33, 49, 52, 53, 56, 57, 65, 66) is provided which applies an axial pre-tensioning force to the axial bearings. The invention additionally relates to a robot comprising such a joint bearing and to a method for installing a joint bearing for a robot.