Dual-Plane Shear Limb Support to Prevent Twisting and Jamming
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Solution Overview
Problem
Shears used for cutting materials with high shearing forces often experience twisting and jamming, leading to unclean or incomplete cuts due to inadequate support during the cutting process.
Innovation Solution
The shears are designed with a planar support on both sides of the revolute joint, featuring a double connection between overlapping plate-like regions, a penetration slot, and a stop pin to ensure reliable support and alignment of cutting edges, allowing them to pass each other securely in the closed position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shears are designed with sufficient support structure to prevent twisting during high-force cutting, then the reliability and cutting quality improve, but the device complexity and bulk increase
Solution Approach 1:
The patent transitions from a single-plane support structure to a dual-plane support structure by extending one limb relative to the other limb on the handle side of the revolute joint. This creates overlapping plate-like regions that provide support in two dimensions (both sides of the rotational plane), preventing twisting more effectively while maintaining a relatively compact design through the overlapping configuration rather than adding separate support elements.
Solution Approach 2:
The support structure is segmented into distinct functional regions: the overlapping plate-like regions provide structural support, the penetration slot allows for controlled movement and alignment, and the stop pin provides positional limitation. This segmentation allows each element to perform its specific function efficiently without requiring a monolithic complex structure.
2Stability of the object's composition
If the cutting edges are fully supported along their entire length, then the stability during cutting improves, but the ability to achieve clean complete cuts deteriorates due to restricted movement
Solution Approach 1:
The support structure is applied locally rather than uniformly along the entire cutting edge. The overlapping plate-like regions provide support at the handle side of the revolute joint where structural stability is needed, while the cutting edges themselves remain exposed and free to move relative to each other, enabling clean cutting action without excessive constraint.
Solution Approach 2:
The support is provided partially - only in the region of overlap on the handle side of the revolute joint - rather than along the entire length of the limbs. This partial support is sufficient to prevent twisting and provide stability during high-force cutting, while allowing the cutting edges the necessary freedom of movement to achieve complete clean cuts.
3Productivity
If the limbs are designed with full exposure of cutting edges on outer surfaces, then the cutting performance improves, but the structural support and resistance to twisting deteriorate
Solution Approach 1:
The patent resolves this contradiction by adding support in another dimension - the overlapping plate-like regions extend in the width direction and provide support on both sides of the rotational plane. This allows the cutting edges to remain exposed on the outer surfaces for efficient cutting while the overlapping regions provide the necessary structural reinforcement against twisting forces through the dual-plane support configuration.
Data Source
AI summary
Shears having two limbs connected at a revolute joint, each limb comprising a handle region at one end and a cutting edge at the other end. One limb is fixed relative to the revolute joint during an opening and closing movement, and one limb is movable. The limbs move between an open position and a closed position while being limited by a stop and, in the closed position, the cutting edges pass each other over substantially their entire length. On the handle side of the revolute joint, one limb extends relative to the other limb such that it is supported in a planar manner on both sides in a region of overlap with the other limb, wherein the limbs comprise surface regions which, in the closed position, rest against one another in the region in which they are on top of each other and are each exposed on the opposite side.