Rotary Knife Double-Beveled Inner Surface Reduces Tissue Resistance
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Solution Overview
Problem
Powered rotary knives used in meat processing face high resistance due to surface tension between the rotating blade and tissue, which leads to worker fatigue and injury, and existing methods to reduce this tension, such as grinding hollow areas, are inadequate, while also requiring frequent sharpening.
Innovation Solution
A rotary knife with an annular blade featuring a double-beveled inner surface, where the first section extends from the cutting edge and the second section is angled further away, creating an air gap that reduces surface tension and allows for multiple sharpenings without significant axial height reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the blade surface is modified to create an air gap (e.g., grinding hollow areas), then surface tension between the blade and tissue is reduced, but the blade structure becomes more complex and manufacturing difficulty increases
Solution Approach 1:
The patent applies local quality by creating a double-beveled configuration only on the inner blade surface that contacts tissue, while the outer surface and cutting edge remain conventional. This localized modification reduces surface tension in the critical contact area without requiring complex modifications to the entire blade structure, maintaining manufacturing simplicity while achieving the force reduction benefit
Solution Approach 2:
The patent introduces a dimensional change by adding a second bevel angle to the inner blade surface, creating a three-dimensional angled configuration rather than a flat surface. This dimensional modification creates an air gap between the blade and tissue, reducing surface tension and the force required to move the knife through tissue
2Reliability
If the blade is sharpened repeatedly, then cutting performance is maintained, but the axial height of the blade is significantly reduced
Solution Approach 1:
The patent applies preliminary action by pre-configuring the inner blade surface with a double-beveled angle configuration before sharpening operations begin. This preliminary geometric setup ensures that as material is removed during repeated sharpening, the axial height loss is minimized because the sharpening process removes material more efficiently from the beveled surfaces rather than from a flat surface, thereby maintaining cutting performance while preserving blade length
3Ease of manufacture
If the inner blade surface is made flat, then manufacturing is simple, but surface tension with tissue is high causing worker fatigue
Solution Approach 1:
The patent applies local quality by modifying only the inner blade surface that contacts tissue with a double-beveled configuration, while keeping the rest of the blade structure simple and conventional. This localized change reduces surface tension and improves ease of operation without significantly complicating the overall manufacturing process
Solution Approach 2:
The patent introduces a dimensional change by adding angular complexity to the inner blade surface through double bevelling, transforming it from a flat two-dimensional surface to an angled three-dimensional surface. This creates an air gap that reduces surface tension and makes the knife easier to operate, while the modification is confined to a specific area rather than the entire blade
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 double-beveled inner surface significantly reduces the force required to move the knife through tissue by minimizing surface tension and extends the blade's sharpening life by maintaining a suitable axial height despite repeated sharpening.
Implementation Method 1
one of the principal factors contributing to resistance to the knife moving through the tissue is surface tension between the rotating blade and the tissue
Data Source
AI summary
A rotary knife includes a rotatable annular blade. The blade includes a blade wall presenting an annular inner surface terminating at a cutting edge. The annular inner surface includes a first section and a second section, with the first section extending from the cutting edge and the second section being located further from the cutting edge than the first section. The first and second sections define first and second angles, respectively, relative to an imaginary plane transverse to the axis about which blade rotates. The second angle is greater than the first angle.