Workpiece Holding Apparatus With Spherical Coupling
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Solution Overview
Problem
Existing apparatuses for holding workpieces with complex shapes, particularly those with double curvature, face challenges in precise and stable positioning without deformation, especially when the thickness is significantly less than the width and length, and require complex and costly configurations with multiple motors to orient gripping devices effectively.
Innovation Solution
The apparatus employs orientable gripping devices with spherical couplings and reference elements that allow for automatic and programmable orientation in space, using a reduced number of motors, with each actuator driven to adjust its gripping device through contact with a reference element, minimizing stress on the workpiece and enabling precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple motors are used to orient gripping devices with two degrees of freedom, then the gripping devices can be precisely oriented in space, but the device complexity and cost increase
Solution Approach 1:
The gripping device uses its own weight and the stiffness of the workpiece to automatically orient itself during the gripping operation. The spherical coupling allows the gripping device to self-adjust its orientation through the interaction between its weight force and the workpiece stiffness, eliminating the need for additional motors to provide orientation control
Solution Approach 2:
The system transitions from a static orientation control mechanism (fixed motors) to a dynamic self-adjusting mechanism where the gripping device orientation is determined by the interaction between the device weight, spherical coupling mobility, and workpiece stiffness during the gripping operation
2Manufacturing precision
If the workpiece is held stiffly in a fixed position, then precise machining can be performed, but deformation or damage may occur to flexible or large-dimensional workpieces
Solution Approach 1:
The system changes the compliance parameter of the gripping device by allowing orientation adjustment through the spherical coupling. This compliance enables the gripping device to adapt to the workpiece flexibility, distributing forces more evenly and preventing localized stress concentrations that would cause deformation
Solution Approach 2:
The workpiece stiffness and gripping device weight create a preliminary self-adjusting action that orients the gripping device appropriately before the actual machining forces are applied, ensuring optimal force distribution from the beginning of the operation
3Ease of operation
If pneumatic gripping devices are made self-adjustable through weight and workpiece stiffness, then orientation is simplified, but non-perfect self-adjustment requires operator intervention
Solution Approach 1:
The system incorporates feedback through the mechanical interaction between the gripping device weight, spherical coupling, and workpiece stiffness. This feedback mechanism automatically corrects orientation deviations during the gripping operation, reducing the need for operator intervention while maintaining adaptability
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 allows for precise, stable, and deformation-free positioning of complex-shaped workpieces with reduced motor usage, minimizing stress and enabling universal adaptability to different shapes, while maintaining a simple and cost-effective design.
Implementation Method 1
each actuator carries a gripping device which is orientable in space with respect to said actuator... said gripping device being provided with a spherical coupling through which said gripping device is able to perform a rotational movement
Implementation Method 2
said reference element giving rise to abutting means arranged at a certain distance from a fulcrum (for example the centre of a spherical coupling of the orientable head of the gripping device) so that the action of such abutting means generates torque that rotates the gripping device around the fulcrum
Implementation Method 3
Providing each linear actuator with a pneumatic gripping device (suction cup)
Data Source
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AI summary
An apparatus is disclosed for holding a workpiece in machining position, wherein a plurality of linear actuators is arranged for defining an engaging and supporting surface at least partially shaped like the workpiece, wherein each linear actuator carries a gripping device that is orientable in space; each actuator is further associated with a respective positionable reference element, each linear actuator being driven in such a manner as to bring the gripping device into contact against the reference element and then to lodge in a desired orientation, the lodging being achieved by the effect of the contact of the gripping device against the reference element located in a preset reference position.