Fluid Gripper Joints for Curved Workpiece Orientation Control
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Solution Overview
Problem
There is a need for gripping apparatuses and methods that can accommodate workpieces with various shapes, particularly those with thin or porous wall structures, such as honeycomb bodies, which require precise orientation and handling during manufacturing or processing operations without over-constraining them.
Innovation Solution
A fluid-operated gripping apparatus with equally spaced actuators and end effectors, each with a three-degree-of-freedom rotational joint, that uses a pressurized fluid circuit to maintain equal pressure and contact the workpiece at multiple points, allowing for precise orientation and handling of workpieces with curved sidewalls, including cylindrical honeycomb structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If multiple actuators are used to grip the workpiece, then the gripping force and stability are improved, but the risk of over-constraining the workpiece and disrupting its orientation increases
Solution Approach 1:
Each actuator is equipped with a spherical joint that provides local rotational freedom at the contact point between the end effector and the workpiece. This allows each gripping point to independently accommodate the workpiece's curvature and orientation, distributing the gripping force while maintaining the workpiece's overall orientation without over-constraint.
Solution Approach 2:
The spherical joints introduce dynamic adaptability to the gripping system, allowing the end effectors to automatically adjust their contact points and orientations in response to the workpiece's shape and position. This dynamic adjustment ensures stable gripping force application while preserving the workpiece's intended orientation during handling.
2Device complexity
If the actuators are coupled to a single pressurized fluid source, then the system complexity is reduced, but the ability to apply differential forces to different parts of the workpiece is limited
Solution Approach 1:
The system utilizes the natural pressure equalization property of fluid circuits to achieve adaptive force distribution. When actuators are connected to a common fluid source, pressure equalizes across all actuators, causing them to extend until they contact the workpiece. The spherical joints then allow each actuator to apply force in its optimal direction, achieving differential force application without complex valve systems.
Solution Approach 2:
The fluid circuit leverages the workpiece's own geometry and position to automatically distribute forces appropriately. As pressure equalizes in the fluid circuit, each actuator self-adjusts its extension based on the resistance it encounters, with the spherical joints enabling each actuator to apply force in the direction most suitable for its contact point on the workpiece.
3Stability of the object's composition
If end effectors contact the workpiece at multiple points, then the stability of gripping is improved, but the risk of over-constraining the workpiece and altering its orientation increases
Solution Approach 1:
The gripping system divides the contact interface into multiple discrete spherical joint locations, with each joint providing localized rotational freedom. This segmentation allows each contact point to independently stabilize the workpiece without collectively over-constraining it, as each spherical joint accommodates local variations in orientation while the overall system maintains precise control.
Solution Approach 2:
The end effectors utilize a composite contact mechanism combining spherical joints (providing rotational freedom) with multi-point contact surfaces (providing stability). This composite approach allows the system to achieve both gripping stability through multiple contact points and orientation precision through the rotational adaptability of the spherical joints.
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 apparatus effectively holds workpieces in a working orientation, enabling precise alignment and handling of workpieces with curved sidewalls, accommodating different sizes and shapes without over-constraining them, and allows for adjustable gripping force, enhancing processing efficiency and throughput.
Implementation Method 1
A fluid circuit (e.g., a pneumatic or hydraulic circuit) is provided to cause the actuators to extend (i.e., during a closing stroke of the gripping apparatus) according to the force equalization principle. With the actuators coupled to the same pressurized fluid source, only the actuator experiencing the least resistance to extension will move.
Implementation Method 2
The fluid circuit is configured to: (i) supply pressurized fluid to the extend chamber of each actuator during a closing stroke of the gripping apparatus, (ii) inhibit backflow of pressurized fluid from the extend chamber of each actuator toward a pressurized fluid source
Implementation Method 3
each end effector comprises a three-degree-of-freedom rotational joint. Such features avoid over-constraining the workpiece, thereby permitting orientation of the workpiece (e.g., relative alignment of an axis of the workpiece such as the relative alignment of an axis of roatation of a cylindrical honeycomb body) to be maintained while gripping is performed.
Implementation Method 4
In certain embodiments, over-constraining the workpiece may be further avoided by providing a backstop configured to contact an end face of the workpiece, with the backstop being coupled with a three-degree-of-freedom rotational backstop joint.
Data Source
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Figure 2B
AI summary
A fluid-operated gripping apparatus for holding a workpiece having a curved sidewall in a working orientation, and associated methods for gripping and holding a workpiece, are provided. Three fluid-operated actuators, each including an actuator rod and a moveable piston arranged within a cylinder, are equally spaced around a perimeter of a workpiece and receive fluid from a single pressurized fluid source. A fluid (e.g., hydraulic or pneumatic) circuit causes the actuators to extend during a closing stroke of the gripping apparatus according to the force equalization principle. Each actuator includes an end effector pivotally coupled with an actuator rod and configured to contact a surface of the workpiece at exactly two points. A backstop configured to contact an end face of the workpiece is coupled with a rotational joint.