Chamfered Cutting Insert Geometry to Prevent Surface Interference
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Solution Overview
Problem
Existing cutting inserts with a center angle of 180° for high-hardness materials face interference with machined surfaces, chip bite leading to sudden fracture, and reduced bonding strength and rigidity due to narrow joint areas and reduced width around brazed portions.
Innovation Solution
A cutting tool design with a chamfered edge portion behind the cutting edge, a center angle greater than 180°, and a back taper with a gradually decreasing width, along with a chamfered boss surface and recessed portions for coolant flow, to prevent interference and enhance bonding strength and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the center angle of the cutting edge is set to about 180° to ensure a large joint area and bonding strength, then the bonding strength and insert rigidity are improved, but the edge portion interferes with the machined surface and causes chip bite leading to sudden fracture
Solution Approach 1:
The patent applies local quality by chamfering only the edge portion (not the entire cutting edge) to create a localized clearance geometry. This allows the cutting edge to maintain its full strength and bonding area while the chamfered edge portion specifically prevents interference with the machined surface, addressing the contradiction between bonding strength and interference prevention.
2Object-affected harmful factors
If the height of the edge portion is reduced to the same level as the rake surface to avoid interference, then the interference with machined surface is eliminated, but the joint area between base insert and cutting edge is reduced leading to insufficient bonding strength
Solution Approach 1:
Instead of reducing the overall height of the cutting edge, the patent applies local quality by chamfering only the edge portion. This localized modification creates the necessary clearance to prevent interference with the machined surface while preserving the full height and bonding area of the cutting edge at its base, thereby maintaining bonding strength.
3Object-affected harmful factors
If the back taper is increased to avoid interference by the edge portion, then the clearance with machined surface is improved, but the width of the insert around the brazed portion is reduced leading to insufficient bonding strength and decreased rigidity
Solution Approach 1:
The patent applies local quality by concentrating the interference-prevention function in the chamfered edge portion rather than increasing the overall back taper. This localized chamfering creates the necessary clearance without reducing the insert width around the brazed portion, thereby maintaining both bonding strength and insert rigidity.
4Strength
If the center angle of the cutting edge is increased to about 180° to ensure large joint area, then the bonding strength is improved, but the edge portion remains in edge shape causing chip bite and sudden fracture
Solution Approach 1:
The patent applies local quality by chamfering the edge portion to specifically address chip bite prevention. This localized geometric modification at the edge portion eliminates the sharp edge that causes chip bite and sudden fracture, while the rest of the cutting edge maintains its full-strength geometry and large joint area for bonding strength.
Data Source
AI summary
For a cutting insert to be used particularly for copy machining or finish machining, a cutting tool is provided that can avoid interference with a machined surface, while suppressing deterioration of a rigidity and a bonding strength, occurrence of breakage and chattering, or the like. A cutting tool includes a base insert member extending along a longitudinal direction and a cutting edge member provided at a longitudinal end portion of the base insert member. The cutting edge member includes a rake surface, a flank surface, an arcuate cutting edge, a breaker wall, and a boss portion including a boss surface. A center angle of the cutting edge is not less than 180°, and each of edge portions present behind the cutting edge along the longitudinal direction has at least a portion that is chamfered.