Shape-Memory Alloy Actuator for Magnetic Workpiece Clamping
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Solution Overview
Problem
Devices for gripping and withholding ferromagnetic workpieces, such as sheet-steel elements, require a simpler, cost-effective, and less encumbered solution than traditional pneumatic actuators.
Innovation Solution
The use of shape-memory actuator means, comprising shape-memory metal alloy wires that undergo a phase transition with temperature changes, to control the displacement of a magnet-holder member between operative and retracted positions, with auxiliary magnets ensuring stable positioning without continuous energy expenditure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pneumatic actuators are used to control the magnet-holder member, then reliable displacement control is achieved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the pneumatic actuator system with a shape-memory alloy-based actuation system. The shape-memory wires directly convert thermal energy to mechanical displacement, eliminating the need for pneumatic cylinders, valves, and associated control mechanisms. This substitution maintains reliable displacement control while significantly reducing device complexity.
Solution Approach 2:
The invention utilizes the temperature-dependent phase transition parameter of shape-memory alloys to control the magnet-holder member displacement. By changing the temperature parameter (via electrical heating), the alloy transitions between martensitic and austenitic phases, producing controlled linear displacement. This parameter-based control achieves reliable actuation without complex mechanical systems.
2Ease of operation
If pneumatic actuators are used to control the magnet-holder member, then displacement control is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive pneumatic actuators with simpler shape-memory alloy wires and electrical heating elements. This substitution maintains ease of operation for displacement control while significantly reducing manufacturing cost by eliminating complex pneumatic components and their associated infrastructure.
Solution Approach 2:
The invention employs relatively simple and inexpensive shape-memory alloy wires and heating elements instead of costly pneumatic actuators. While shape-memory alloys have specific material costs, the overall system becomes more cost-effective by eliminating expensive pneumatic components, seals, valves, and maintenance requirements.
3Force
If pneumatic actuators are used, then sufficient actuation force is achieved, but axial encumbrance increases
Solution Approach 1:
The patent replaces the bulky pneumatic actuator with compact shape-memory alloy wires that generate actuation force through thermal expansion during phase transition. This substitution maintains sufficient actuation force to move the magnet-holder member while dramatically reducing the axial space required, as the shape-memory wires can be arranged concentrically or in parallel within a compact volume.
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 solution provides a compact, energy-efficient, and cost-effective device for gripping and clamping ferromagnetic workpieces, maintaining stable positions without continuous electric supply and minimizing axial encumbrance.
Implementation Method 1
shape-memory actuator elements, which are constituted by a shape-memory metal alloy and are designed to undergo a phase transition when their temperature exceeds a predetermined threshold value
Implementation Method 2
a wire made of shape-memory metal alloy that undergoes a reduction in length when its temperature exceeds the threshold value
Implementation Method 3
means for supplying an electric current through said shape-memory actuator elements so as to bring their temperature above said threshold value
Implementation Method 4
a main magnet, which generates a magnetic field and adheres to a ferromagnetic workpiece to be clamped so as to clamp the workpiece against a front end of the casing
Implementation Method 5
an auxiliary magnet, which generates a magnetic field of lower intensity than that of the main magnet. The auxiliary magnet adheres to a metal wall of the casing of the device when the magnet-holder member is in its retracted position so as to keep the magnet-holder member stably in said retracted position
Data Source
AI summary
A magnetic device for gripping and clamping workpieces, in particular sheet-steel elements (L), comprises a supporting casing (2), slidably mounted within which is a magnet-holder member (4) carrying a main permanent magnet (M). The magnet-holder member (4) can be displaced between an advanced, operative, position, in which the main magnet (M) is designed to grip and clamp a workpiece (L), and a retracted, inoperative, position. The movement of the magnet-holder member (M) is controlled by shape-memory actuator means (A1, A2, B, E).