Shear Blade Insert Angle to Reduce Stress Concentration
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Solution Overview
Problem
Existing cutting devices face challenges in achieving improved cutting performance, stability, and durability due to complex designs with intricate fastening systems that lead to stress concentrations and material failure, particularly in hydraulic rescue tools.
Innovation Solution
A portable cutting device with a novel design featuring a recess for the cutting insert at an acute angle to the contact surface, eliminating the need for clamping jaws and transferring stress to a positive locking surface, combined with angled surface sections and profiling to enhance force absorption and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a complex fastening system with clamping jaws and pins is used to secure the cutting insert, then the cutting insert can be firmly held in place, but stress concentrations occur at the fasteners leading to material failure and reduced durability
Solution Approach 1:
The patent removes the complex fastening system (clamping jaws and pins) entirely and replaces it with a simple recess that receives the cutting insert. The recess geometry itself provides the securing function through friction and geometric interlocking, eliminating the source of stress concentrations while maintaining adequate holding force.
Solution Approach 2:
The patent merges the functions of holding and securing the cutting insert into the recess structure itself. The recess combines geometric constraint (through its shape and orientation) and frictional holding in a single integrated feature, eliminating the need for separate fastening components that create stress concentrations.
2Strength
If additional recesses and fastening components are added to secure the cutting insert, then the cutting insert can be firmly attached, but manufacturing time and costs increase
Solution Approach 1:
The patent extracts and removes all additional fastening components (clamping jaws, pins, screws) and complex recesses, leaving only a simple recess in the blade body that receives the cutting insert. This dramatically simplifies the manufacturing process while maintaining adequate attachment strength through the recess geometry and friction.
Solution Approach 2:
Instead of adding complex fastening elements to secure the cutting insert, the patent inverts the approach by using a simple recess that passively secures the insert through its geometry. The cutting insert itself becomes part of the securing mechanism through friction and geometric interlocking, rather than requiring separate fastening components.
3Productivity
If the cutting blade has a pointed design to increase cutting effectiveness, then the cutting edge can penetrate material more easily, but the risk of breakage increases due to twisting forces and stress concentrations
Solution Approach 1:
The patent uses a composite structure where a hard cutting insert (made of wear-resistant material) is received in a recess in the blade body. This composite design allows the cutting edge to be very hard and effective for cutting, while the blade body provides structural support and absorbs twisting forces, preventing breakage of the cutting edge itself.
Solution Approach 2:
The patent extracts the cutting edge from the blade body and makes it a separate replaceable insert. This allows the cutting edge to be optimized for cutting effectiveness while being protected from breakage by the recess structure and the blade body's ability to absorb stresses. When the insert wears or breaks, it can be replaced without replacing the entire blade.
Data Source
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AI summary
The invention relates to a shear blade (2) for a portable, in particular hydraulic cutting device, preferably a rescue device having a blade body (9), wherein the blade body (9) has an assembly region (18) and a cutting region (15), a cutting (16) in the cutting region (15), a contact surface (13), located on one side of the cutting edge (16), for an additional shear blade, and an outer surface (14), located on the other side of the cutting edge (16), which is provided in order to act on the object to be cut, wherein the cutting region (15) has a recess (22) for receiving a cutting insert (21), wherein the recess (22) is designed such that the cutting insert (21) can be inserted into the recess (22) at an acute angle δ to the contact surface (13) of the shear blade (2).