Thread Cutter Edge Geometry for High-Hardness Load Sharing
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Solution Overview
Problem
Existing screw thread cutters face excessive cutting load issues when machining high hardness materials, leading to potential damage of the finishing edge due to the concentration of cutting load on the valley portion between the tip side finishing edge and the preceding edge.
Innovation Solution
A screw thread cutter design with at least three screw thread-cutting edges, including a preceding edge and two finishing edges, where the first and second valley portions are formed to distribute the cutting load, with the first valley portion being deeper than the second, and the finishing edge-thread ridge heights being equal, to prevent excessive load concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two finishing edges are provided on a posterior end side of the preceding edge, then the screw groove shape is maintained even when the tip side finishing edge becomes worn, but excessive cutting load acts on the valley portion between the tip side finishing edge and the preceding edge
Solution Approach 1:
The invention divides the finishing edge into two separate finishing edges (first and second) positioned at different locations. The first finishing edge is positioned to cut the valley portion with the preceding edge, while the second finishing edge is positioned posteriorly to maintain the screw groove shape. This segmentation distributes the cutting load across multiple edges and prevents excessive concentration on a single valley portion.
2Manufacturing precision
If the valley portion between the tip side finishing edge and the preceding edge cuts the apex of the thread ridge, then the screw groove is formed, but the cutting load excessively increases on this valley portion
Solution Approach 1:
The invention creates different valley portion depths at different locations: the first valley portion (between the preceding edge and first finishing edge) has a greater depth than the second valley portion (between the first and second finishing edges). This local differentiation in valley depth distributes the cutting load, with the deeper first valley portion accommodating more material removal while the shallower second valley portion reduces excessive load concentration.
3Manufacturing precision
If thread cutting is performed on high hardness material, then the female screw portion is formed, but the finishing edge may be damaged due to excessive cutting load shock
Solution Approach 1:
The invention positions the second finishing edge posteriorly to beforehand cushion and absorb excessive cutting loads that may shock the first finishing edge during thread cutting on high hardness materials. The second finishing edge acts as a buffer that prevents load concentration from directly damaging the primary cutting edges, thereby enhancing overall edge durability.
Data Source
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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.