Sickle Blade With Segmented Cutting Angles
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Solution Overview
Problem
Cutting blades experience issues with sticking of material, leading to rapid wear, high cutting force, and adhesion of slices to the knife, particularly due to the sticking of severed slices to the inclined cutting surface, which is exacerbated by small cutting angles and uneven surface transitions.
Innovation Solution
A cutting blade design featuring a large cutting angle of at least 10°, with a radially inward groove on the front side and a flat intermediate area parallel to the rear side, minimizing sticking by guiding slices away from the knife and reducing friction, while maintaining ease of production and re-sharpening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a small cutting angle is used, then the cutting force is reduced, but the slice adheres to the cutting surface
Solution Approach 1:
The cutting surface is segmented into multiple zones with different angles: a first cutting surface with a smaller angle (5-15°) for initial penetration with low force, and a second cutting surface with a larger angle (20-40°) for complete separation and preventing adhesion. This segmentation allows each zone to perform its specific function optimally.
Solution Approach 2:
Different regions of the cutting blade are given different surface properties and angles. The first cutting surface has a smaller angle suited for penetration, while the second cutting surface has a larger angle suited for preventing adhesion. This local differentiation resolves the contradiction by applying the appropriate angle in the appropriate location.
2Object-generated harmful factors
If a large cutting angle is used, then slice adhesion is prevented, but the cutting force increases
Solution Approach 1:
The cutting process is divided into two stages with different angles: initial penetration using a smaller angle (5-15°) to minimize force, and final separation using a larger angle (20-40°) to prevent adhesion. This segmentation allows the system to achieve both low force and adhesion prevention.
Solution Approach 2:
The first cutting surface with the smaller angle performs the preliminary action of penetrating the material with minimal force, preparing the way for the second cutting surface to complete the cut and prevent adhesion. This preliminary action reduces the overall force requirement while still achieving adhesion prevention.
3Ease of operation
If the cutting surface is extended radially, then slice guidance is improved, but the cutting effort increases
Solution Approach 1:
The cutting surface is divided into two segments with different radial extensions and angles. The first cutting surface has limited radial extension with a small angle for low-force penetration, while the second cutting surface extends further radially with a larger angle for effective slice guidance and adhesion prevention. This segmentation optimizes both guidance and force requirements.
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
The knife (1) has a convex bent cutting edge (2) whose distance is increased from a rotational axis (10) in progression direction of a contact region of the knife to a cutting material. The cutting edge is provided with a spiral-shaped outer circumferential contour. A cutting surface of front side (8) of the knife is arranged at cutting angle of 33 degrees to a main plane. A groove is arranged on the front side and radial-inwardly displaceable with respect to the cutting surface. The groove is extended along entire peripheral length of the cutting edge.