Tool Holder Using Shape Memory Alloy for Rapid Clamping
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Solution Overview
Problem
Existing tool holders are complex and costly due to the need for separate devices and systems for clamping and unclamping tools, leading to increased geometric errors, complexity, and reduced productivity due to time-consuming high-temperature tool replacement processes.
Innovation Solution
A tool holder using a shape memory alloy with a reinforcing portion of tapered or two-dimensional curved shape, combined with a fine pattern for enhanced thermal diffusion and a spacer and locking cap to increase axial tightening force, simplifies the structure and reduces size while improving moment strength and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a tapered collet chuck method is used with separate devices like spring or collet nut, then clamping force is achieved, but the overall structure becomes complicated and geometric tool set-up errors increase
Solution Approach 1:
The patent integrates the clamping mechanism directly into the holder body by forming slits on the outer circumferential surface, eliminating the need for separate collet nuts or springs. The shape memory alloy ring works in conjunction with the integrated slits to provide clamping force, thereby simplifying the overall structure while maintaining effective tool retention.
Solution Approach 2:
The patent utilizes temperature parameter changes to activate the shape memory alloy ring, which automatically adjusts the clamping force. By heating or cooling the shape memory alloy ring, the system transitions between clamped and released states without requiring complex mechanical actuation mechanisms, thus reducing structural complexity.
2Force
If hydraulic chuck method is used with separate pressing system, then tool clamping is achieved, but system configuration becomes complicated and expense increases
Solution Approach 1:
The patent replaces the hydraulic pressing system with a thermal field-based mechanism. Instead of using hydraulic pressure to deform the clamping surface, the system uses temperature changes in the shape memory alloy ring to control expansion and contraction, thereby achieving tool clamping without complex hydraulic infrastructure.
Solution Approach 2:
The shape memory alloy ring undergoes phase transitions between martensite and austenite structures in response to temperature changes. This phase transition enables the ring to reversibly change its dimensional state, providing automatic clamping and release functionality without requiring separate pressing systems or complex mechanical linkages.
3Force
If shrink fit method is used with high-temperature heating, then tool fastening is achieved, but tool replacement time increases and system expense increases
Solution Approach 1:
The patent applies localized thermal treatment only to the shape memory alloy ring rather than heating the entire holder body. The ring is selectively heated or cooled to induce shape memory effect, enabling rapid clamping and release. This localized approach significantly reduces the time and energy required compared to heating the entire holder for shrink fit operations.
Solution Approach 2:
The system employs periodic thermal cycling of the shape memory alloy ring to alternately clamp and release the tool. By applying brief heating or cooling cycles, the tool can be rapidly secured or removed without requiring prolonged high-temperature exposure, thereby reducing tool replacement time and improving productivity.
4Speed
If fine pattern is formed on shape memory alloy surface, then thermal diffusion speed increases, but manufacturing complexity increases
Solution Approach 1:
The patent employs a knurled or curved surface pattern on the shape memory alloy ring instead of flat surfaces. This geometric modification increases the surface area and creates micro-channels that enhance thermal diffusion. The curved pattern is achieved through conventional forming processes, balancing improved thermal performance with manufacturing feasibility.
5Strength
If reinforcing portion with tapered or curved shape is configured, then moment strength and rigidity are improved, but manufacturing complexity increases
Solution Approach 1:
The holder body incorporates a curved or tapered reinforcing portion that follows the natural stress distribution patterns. This curved geometry provides enhanced moment strength and rigidity compared to straight cylindrical forms. The curved shape is integrated into the holder body during forming operations, achieving structural reinforcement without requiring separate assembly steps or complex machining.
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 tool holder simplifies the structure, reduces size, enhances machining precision, and significantly shortens clamping and unclamping times by leveraging the shape memory alloy's thermal properties and increased surface area, while maintaining axial tightening force.
Implementation Method 1
a shape memory alloy ring (120) which tightens or loosens the clamping portion (113) in a radial direction of an axis while being heated or cooled
Implementation Method 2
a speed in response to an operation of clamping and unclamping a shape memory alloy ring is improved by a high thermal diffusion speed caused by a fine pattern
Data Source
Figure 1(A)~1
Figure 2
Figure 3
AI summary
Disclosed is a tool holder (100) using a shape memory alloy. The disclosed tool holder using the shape memory alloy, includes: a holder body (110) including: a coupling portion (111) at a rear side which is coupled to a chuck means; a clamping portion (113) at a front side which has a bore (113a) into which a shank portion (S) of a tool (T) is inserted, a plurality of slits (113b) formed on an external circumferential surface of the clamping portion, communicating with the bore, and arranged in a circumferential direction, and an external thread portion (113d) formed on a tip portion of the external circumferential surface; and a reinforcing portion (112) in which an axial shape of an external circumferential surface between the coupling portion and the clamping portion has any one shape of a tapered shape, a two-dimensional curved line shape, and a horizontal line shape; a shape memory alloy ring (120) which tightens or loosens the clamping portion in a radial direction of the axis while being heated or cooled in a state in which the shape memory alloy ring is fitted on the slits of the clamping portion; a spacer (130) which is interposed between the reinforcing portion of the clamping portion and the shape memory alloy ring; and a locking cap (140) which is thread-coupled to the external thread portion of the clamping portion by an internal thread (141) formed on an inner circumferential surface and prevents the shape memory alloy ring from being moved away.