Sliding Claw Workpiece Locking for High-Force Pin Retention
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Solution Overview
Problem
Conventional locking devices for workpieces on machine tools have limited retaining force due to small contact surface, are costly and unreliable due to mechanical parts wear, and require larger diameters for the support, which reduces pin strength and increases manufacturing costs.
Innovation Solution
A locking device with two curved claws that slide in slots and are actuated by a screw with double threading, engaging a frustum-shaped groove on the pin for high retaining force without increasing the support diameter, and allowing rapid locking and unlocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional inserts with small contact surface are used, then the device structure is simple, but the retaining force is limited
Solution Approach 1:
The patent applies curvature by designing the claws with a curved profile that matches the cylindrical shape of the pin. The curved gripping surfaces at the ends of the claws provide extensive contact area with the pin, transforming the flat insert design into a curved configuration that maximizes surface contact and friction-based retaining force.
2Reliability
If conventional mechanical clamping mechanisms with multiple parts are used, then the device can achieve reliable clamping, but manufacturing costs increase and wear occurs
Solution Approach 1:
The patent merges the clamping function into the claw structure itself, which is a single integral component. The curved claws with gripping surfaces directly engage the pin without requiring separate clamping elements, cam mechanisms, or adjustable components. This consolidation eliminates multiple mechanical parts while maintaining reliable clamping through the geometry of the curved claws.
Solution Approach 2:
The patent replaces complex mechanical clamping systems with a friction-based retention system. Instead of using cam actions, threaded adjustments, or movable clamping elements, the design relies on the friction between the curved gripping surfaces of the claws and the pin surface, substituting mechanical interlocking with friction-based retention.
3Ease of operation
If the diameter of the hollow cylindrical support is increased to accommodate the clamping mechanism, then the clamping function is achieved, but the useful diameter for the pin is reduced and manufacturing costs increase
Solution Approach 1:
The patent extracts the clamping function from a separate mechanical mechanism and integrates it directly into the claw structure. The curved claws themselves perform the clamping action through their geometry and friction, eliminating the need for additional clamping components that would occupy space within the support, thereby preserving the useful diameter for pin accommodation.
4Strength
If conventional inserts are used, then the device structure is simple, but the manufacturing precision and retention strength are limited
Solution Approach 1:
The curved profile of the claws with their cylindrical gripping surfaces provides inherent mechanical advantage and distributes contact forces more evenly across the pin surface. This curved geometry enhances retention strength by maximizing friction contact area and improving force distribution, while the standardized curved shapes are easier to manufacture with high precision using conventional machining methods.
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 device achieves strong, reliable, and cost-effective retention with high force capability and rapid operation, maximizing pin diameter without enlarging the support, thus enhancing productivity and reducing wear.
Implementation Method 1
a screw (28) with at least one threaded end (28L) which is adapted to engage a corresponding threaded hole (20L) provided in one of the claws (20)
Implementation Method 2
The reduced contact surface between the ends of the inserts and the pin inevitably limits the maximum retaining force that can be exerted by the device
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A support (14) extending about an axis (A) has an axial cavity (16), adapted to receive a pin (12) fixed to the workpiece (W), and has retention means for retaining the pin (12) axially. The retention means comprise two claws (20, 22) with curved profiles and opposing concavities, which are inserted so that they can slide in respective mutually opposite slots (24, 26) of the support (14) in order to translate between an open position, in which they do not interfere with the insertion/extraction of the pin (12), and a closed position, in which they engage a circumferential groove (18) of the pin (12) that has been inserted into the support (14), in opposing positions. The claws (20, 22) are functionally interconnected in an opening/closing relationship by an actuation screw (28) which is positioned so as not to interfere with the pin (12) and has threaded ends (28L, 28R) which engage corresponding threaded holes (20L, 22R) which are provided in the claws (20, 22).