Screw Thread Cutter Edge Layout for Lower Finishing Load
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Solution Overview
Problem
In screw thread cutters, the excessive cutting load on the valley portion between the tip side finishing edge and the preceding edge leads to potential damage, especially when cutting high hardness materials, due to the concentration of load on the root portion of the finishing edge.
Innovation Solution
The design incorporates at least three screw thread-cutting edges with a preceding edge and two finishing edges, featuring distinct valley portions to distribute the cutting load, where the first valley portion is deeper than the second, and the finishing edge-thread ridge heights are equal, allowing the first finishing edge to finish-cut the valley portion and the second to handle the apex, thereby reducing the load on any single edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the valley portion between the tip side finishing edge and the preceding edge is used for cutting the apex of the screw head, then the screw groove shape is formed, but the cutting load excessively increases causing damage to the finishing edge
Solution Approach 1:
The invention divides the finishing edge into multiple segments (first finishing edge and second finishing edge) positioned at different axial locations. The first finishing edge cuts the valley portion while the second finishing edge cuts the apex, segmenting the cutting function to distribute the load and prevent damage to any single edge segment.
Solution Approach 2:
The invention transitions from a single finishing edge to multiple finishing edges arranged in the axial dimension. By adding the axial dimension to the finishing edge configuration, the cutting load is distributed across multiple edges along the axial direction, preventing excessive concentration on one edge.
2Manufacturing precision
If two finishing edges are provided with equal thread ridge heights, then the screw groove shape is maintained, but the valley portion between them experiences excessive cutting load
Solution Approach 1:
The invention applies different local qualities to different parts of the finishing edge structure. The first and second finishing edges have equal thread ridge heights for maintaining screw groove shape, but their valley portion depths are different, with the first valley portion being deeper. This local differentiation allows load distribution while maintaining overall geometric consistency.
Solution Approach 2:
The invention introduces asymmetry in the valley portion depths between the first and second finishing edges. While the thread ridge heights are symmetric and equal, the valley depths are asymmetric (first valley deeper than second), creating an asymmetric load distribution that reduces excessive cutting load on any single valley portion.
3Productivity
If the preceding edge and tip side finishing edge are used for main cutting, then productivity is maintained, but the root portion of the finishing edge suffers from excessive load concentration
Solution Approach 1:
The invention segments the finishing edge into multiple axial positions (first and second finishing edges) to distribute the cutting function. This segmentation allows the cutting load to be shared across multiple edges, maintaining productivity while reducing the strength demand on any single edge's root portion.
Solution Approach 2:
The invention changes the geometric parameters of the finishing edges, specifically making the thread ridge heights equal while creating different valley depths. This parameter optimization allows efficient cutting while reducing stress concentration at the root portions of the finishing edges.
Data Source
AI summary
In a screw thread cutter, a screw thread-cutting edge is formed on an outer periphery of a tip portion of a cutter body. Finishing edge-thread ridge height from a tangent line passing through valley bottoms of second and third valley portions to outer peripheral ends of first and second finishing edges are equal to each other. A preceding edge-thread ridge height from the tangent line to an outer peripheral end of a preceding edge is lower than each of the finishing edge-thread ridge height. A first valley portion-depth from the outer peripheral end of the first finishing edge to the valley bottom of the first valley portion is deeper than a second valley portion-depth from the outer peripheral end of the second finishing edge to the valley bottom of the second valley portion.