Double-Collet Chuck Structure for Accurate Thin-Wall Clamping
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Solution Overview
Problem
The existing collet chuck designs, particularly the pulled-in type, cause workpiece distortion due to thin wall thickness and inferior centering accuracy, and the fixed collet chuck structure makes component replacement difficult and centering less accurate.
Innovation Solution
A collet chuck with a double collet mechanism, featuring a mandrel with a truncated conical outer tapered surface, a first collet with intermediate claws for sliding contact, and a second collet with chuck claws that expand radially without moving the workpiece axially, supported by a collet support member for axial movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pulled-in collet chuck is used, then the chuck claws expand to clamp the workpiece, but the workpiece is pulled in together during clamping causing distortion
Solution Approach 1:
The collet body is divided into two separate collets: a first collet that moves axially and a second collet that remains stationary. This segmentation allows the clamping function to be separated from the axial movement function, enabling the workpiece to be clamped without being pulled in axially, thus preventing distortion while maintaining clamping accuracy.
Solution Approach 2:
The first collet acts as an intermediary between the mandrel and the second collet. It transmits the axial movement force from the mandrel to expand the chuck claws of the second collet, while the second collet itself remains stationary relative to the workpiece, preventing the workpiece from being pulled in during clamping.
2Manufacturing precision
If the outer taper of the mandrel increases in diameter toward the tip, then the mandrel can push the collet outward to clamp the workpiece, but the outer taper gets caught when the collet is pulled out making component replacement difficult
Solution Approach 1:
Instead of having the mandrel taper increase in diameter toward the tip (which causes catching), the mandrel is designed with a truncated conical shape where the taper decreases toward the tip. This inverted approach allows the collet to be easily pulled out for replacement while still maintaining the ability to transmit axial force for clamping through the truncated cone geometry.
3Object-affected harmful factors
If the mandrel moves in axial direction, then the collet can be pushed outward to clamp the workpiece without pulling the workpiece, but the accuracy of centering is inferior to pulled-in collet chuck
Solution Approach 1:
The system is segmented into a moving first collet and a stationary second collet. The first collet handles axial movement for clamping activation, while the second collet remains stationary to provide stable centering support for the workpiece, thereby maintaining high centering accuracy while avoiding workpiece pulling.
Solution Approach 2:
The first collet serves as an intermediary that absorbs the axial movement, allowing the second collet to remain stationary and maintain precise centering. This intermediary structure enables the mandrel to move axially without compromising the centering accuracy provided by the stationary second collet.
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
This configuration allows for accurate clamping without distorting thin-walled workpieces and facilitates easy component replacement by maintaining high centering accuracy and preventing workpiece pulling during clamping.
Implementation Method 1
an intermediate claw formed at each tip portion of the collet main body section has an inner tapered surface formed on an inner side in sliding contact with the outer tapered surface of the mandrel
Implementation Method 2
a chuck claw formed at each tip portion of the collet main body section has an inner sliding contact surface formed on an inner side in sliding contact with an outer sliding contact surface formed on an outer side of the intermediate claw
Data Source
AI summary
A collet chuck including a mandrel, a first collet that is positioned outside the mandrel, an intermediate claw formed at each tip portion has an inner tapered surface formed on an inner side in sliding contact with the outer tapered surface of the mandrel, a second collet that is positioned outside the first collet, a chuck claw formed at each tip portion has an inner sliding contact surface formed on an inner side in sliding contact with an outer sliding contact surface formed on an outer side of the intermediate claw, and a chuck surface formed on an outer side of the chuck claw is brought into contact with a workpiece, and a collet support member that receives a force in an axial direction and supports the first collet movably in the axial direction.