Collet Mechanism Geometry for Stable Contact Stress Distribution
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Solution Overview
Problem
Conventional collet-type mechanisms experience increased maximum contact stress and reduced stability when gripping workpieces of non-nominal sizes, leading to potential galling, damage, and impaired release due to varying contact conditions such as edge or center contact, which are dependent on workpiece size.
Innovation Solution
The collet segments and receiver surfaces are configured with invariant cylindrical surfaces, allowing for controlled contact stress distribution independent of workpiece size, using oblique or right circular cylinders to optimize contact conditions and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional collet-type mechanisms grip workpieces of non-nominal sizes, then the gripping function is maintained, but contact stress increases and stability decreases
Solution Approach 1:
The collet segments are designed with a cylindrical contact surface configuration that creates a localized optimal contact region. This cylindrical geometry concentrates the contact area in a specific zone that maintains uniform stress distribution regardless of workpiece size variations, thereby reducing peak contact stress while preserving gripping capability across different workpiece dimensions.
2Adaptability or versatility
If conventional collet-type mechanisms grip workpieces of non-nominal sizes, then the gripping function is maintained, but stability decreases leading to impaired release
Solution Approach 1:
The cylindrical contact surface configuration creates a localized optimal contact region that enhances stability. This geometry ensures consistent contact conditions and uniform stress distribution regardless of workpiece size, preventing edge contact and improving the reliability of both gripping and release functions across different workpiece dimensions.
3Force
If conventional collet-type mechanisms use conical contact surfaces, then the gripping function is achieved, but contact area is reduced leading to increased stress
Solution Approach 1:
The collet segments are designed with a cylindrical contact surface configuration that creates a localized optimal contact region. This cylindrical geometry concentrates the contact area in a specific zone that maintains uniform stress distribution regardless of workpiece size, thereby reducing peak contact stress while preserving gripping capability across different workpiece dimensions.
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3A~3B
AI summary
A collet-type mechanism for releasably gripping either an external or internal target surface of a tubular workpiece includes a collet receiver defining a collet receiver contact surface configured as a curved lateral surface of a truncated right circular cone, and a segmented collet assembly comprising a plurality of collet segments. Each collet segment defines a workpiece engagement surface configured for gripping engagement with a workpiece target surface, and a collet segment contact surface configured for at least partial contacting engagement with the collet receiver contact surface. The collet segment contact surface may comprise two axially-contiguous regions, one of which corresponds to a curved lateral surface of either an oblique circular cylinder or a right circular cylinder, and the other of which corresponds to a curved lateral surface of a truncated right circular cone.