Cutting Insert Geometry for Secure Holding After Edge Breakage
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Solution Overview
Problem
In cutting tools, if one of the cutting parts breaks, the tool body may fail to sufficiently hold the cutting insert, rendering it unusable before all parts are utilized.
Innovation Solution
The cutting insert features two side surfaces with a fixing hole and an outer circumferential surface with recessed areas between cutting parts, allowing the tool body to contact and securely hold the insert even if one part is broken, through specific geometric configurations and contact points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tool body holds the cutting insert only through contact with cutting parts, then the structure is simple, but the holding reliability deteriorates when a cutting part is broken
Solution Approach 1:
The outer circumferential surface is segmented into four cutting parts and multiple non-cutting outer circumferential surface parts. The non-cutting parts serve as dedicated holding contact portions, separating the cutting function from the holding function. This segmentation allows the tool body to contact both cutting parts (for cutting) and non-cutting parts (for reliable holding), resolving the contradiction between simple structure and reliable holding.
Solution Approach 2:
The outer circumferential surface performs multiple functions: the cutting parts perform cutting while the non-cutting outer circumferential surface parts perform holding. This multi-functionality ensures that even when cutting parts are broken, the holding function remains intact through the non-cutting parts, improving holding reliability without significantly increasing overall structural complexity.
2Reliability
If the outer circumferential surface is flat, then the manufacturing is simple, but the holding stability deteriorates
Solution Approach 1:
The non-cutting outer circumferential surface parts are formed with curved surfaces having specific radii of curvature. These curved surfaces provide stable contact points with the tool body's holding surfaces, improving holding stability. The curvature is carefully designed to balance stability requirements with manufacturing feasibility, avoiding overly complex geometries while achieving reliable holding.
3Productivity
If the cutting insert has four cutting parts, then the productivity increases, but the risk of breakage increases
Solution Approach 1:
The design allows the cutting insert to maintain usability even when one cutting part is broken. The non-cutting outer circumferential surface parts continue to provide reliable holding, enabling the insert to be retained and the remaining cutting parts to be used. This extends the service life of the cutting insert, effectively recovering value even after partial damage, thus improving reliability while maintaining high productivity through multiple cutting parts.
Data Source
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AI summary
Cutting insert 10 which can be sufficiently held by a tool body 11 even if one of its cutting parts 50 - 53 is broken. The cutting insert includes two side surfaces 20, 21 opposed to each other, a fixing hole 22 passing through the centers C1 of the two side surfaces, and an outer circumferential surface 23 that is disposed between the outer circumferential edges of the two side surfaces and is connected to the outer circumferential edges of the two side surfaces. The outer circumferential surface includes four cutting parts, a first outer circumferential surface part 60 that is disposed between the first cutting part 50 and the second cutting part 51, and a second outer circumferential surface part 61 that is opposed to the first outer circumferential surface part and is disposed between the third cutting part 52 and the fourth cutting part 53. In a side view of the side surfaces from the axial direction of the fixing hole, the first outer circumferential surface part and the second outer circumferential surface part each have the center recessed toward the fixing hole, and a virtual arc A1 having the same diameter as the diameter of the circumcircle of the cutting insert is in contact with two points B on each of the outer circumferential surface parts.