Robot Spherical Joint Structure for Wear-Induced Rattle Suppression
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Solution Overview
Problem
Existing spherical joints in robot drive mechanisms can experience rattling due to wear on the inner circumferential surface of the socket or depletion of grease, leading to reduced contact area with the ball member.
Innovation Solution
A spherical joint design that includes a socket with a cage part forming the inner circumferential surface and a connecting part, featuring a fastening member that reduces the space of an opening in the cage part, thereby reducing the radius of curvature and increasing the contact area with the ball member to prevent or suppress rattling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner circumferential surface of the socket is worn out or grease is depleted, then the spherical joint experiences rattling, but the contact area with the ball member decreases
Solution Approach 1:
The invention changes the geometric parameter of the socket by forming a recess in the inner circumferential surface. This recess modifies the contact geometry between the socket and ball member, creating a point contact or line contact region that increases effective contact area even when the overall spherical surface becomes worn. The recess depth and positioning are optimized to maintain reliable contact under various wear conditions and grease depletion scenarios.
2Reliability
If the radius of curvature of the inner circumferential surface is reduced, then the contact area with the ball member increases, but the socket structure becomes more complex
Solution Approach 1:
The invention segments the inner circumferential surface of the socket by introducing a recess that divides the contact surface into distinct regions. This segmentation creates a localized area with different curvature characteristics, effectively reducing the radius of curvature in the recess region while maintaining the overall spherical shape of the socket. This approach suppresses rattling through increased contact area without requiring complete redesign of the entire socket structure.
Solution Approach 2:
The invention applies local quality modification by creating a recess only in specific regions of the inner circumferential surface where it is most effective for reducing rattling. The recess is positioned and dimensioned to locally alter the contact characteristics between the socket and ball member, concentrating the complexity modification in a localized area rather than throughout the entire socket structure.
Data Source
AI summary
A spherical joint of the present disclosure includes a ball member and a socket having an inner circumferential surface configured to spherically contact the ball member. The socket includes a cage part forming the inner circumferential surface and having an opening, and a bar-shaped connecting part provided to the cage part. A fastening member is disposed at the cage part so as to reduce a space of the opening in the extending direction of the connecting part and such that a gap is formed between the fastening member and the ball member. The opening is formed in a part of the inner circumferential surface other than a part where the largest load is applied.