Tangential Cutting Insert Geometry for Balanced Shoulder Milling
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Solution Overview
Problem
Existing tangential cutting inserts have limitations in utilizing all cutting edges effectively due to the geometry, leading to reduced tool life and imbalance under cutting forces, especially when milling shoulders, where only half the length of main cutting edges can be used before wear sets in, and the insert axial rake angle is limited.
Innovation Solution
The design features eight main cutting edges with single associated cutting corners, each with a rake surface extending inward, and a through bore with 90° rotational symmetry, allowing major and minor cutting edges to merge at corner cutting edges, providing balanced cutting forces and extended tool life by using concave major cutting edges and elevated support regions for minor cutting edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the insert axial rake angle is increased to improve chip development and evacuation, then chip flow is improved, but the vertical extent of the increasing incident angle surface increases which adversely affects chip development and evacuation
Solution Approach 1:
The cutting insert is divided into multiple functional surfaces with distinct roles: the decreasing incident angle surface for chip flow control and the increasing incident angle surface for structural support. This segmentation allows each surface to be optimized independently, resolving the contradiction between chip evacuation and structural constraints.
Solution Approach 2:
Different regions of the cutting insert are given different geometric properties. The decreasing incident angle surface is optimized for chip flow with a specific angle range (5-15 degrees), while the increasing incident angle surface provides structural support. This local differentiation allows the insert to simultaneously achieve good chip development and maintain structural integrity.
2Reliability
If only half the length of main cutting edges is used to ensure fresh cutting corners, then cutting corner wear is avoided, but the other half of the cutting edges remain unused reducing productivity
Solution Approach 1:
The cutting insert employs asymmetric geometry where minor cutting edges are positioned at different locations relative to the major cutting edges. This asymmetric arrangement allows the insert to be indexed and reused with all cutting edges becoming accessible, thereby increasing utilization while maintaining cutting corner integrity through proper indexing procedures.
Solution Approach 2:
The insert design incorporates preliminary positioning features and indexing mechanisms that prepare the insert for optimal orientation before each cutting operation. This ensures that the correct cutting edges are presented to the workpiece, allowing systematic utilization of all cutting edges while maintaining their sharpness and effectiveness.
3Shape
If the cutting insert is oriented with negative axial rake angle to provide clearance, then clearance between cutting insert and workpiece is achieved, but the cutting forces are not optimally directed along the major dimension
Solution Approach 1:
The insert geometry incorporates counterbalancing features where the negative axial rake angle provides necessary clearance while the overall insert design, including the positioning in the holder and the geometry of cutting edges, directs cutting forces optimally along the major dimension. The system balances the clearance requirement with force direction optimization through integrated design.
Data Source
Figure 1
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Figure 4
AI summary
A tangential cutting insert (10) has two opposing side surfaces (12) and a peripheral surface (14) extending between the side surfaces. The peripheral surface (14) has four identical end surfaces (18). The intersections of the end and side surfaces include major cutting edges (20). The intersection of end surfaces and adjacent end surfaces include minor cutting edges (24). Each of the major (20) and minor (24) cutting edges has a rake surface (34) extending in an inward direction of the cutting insert (10). In a side view of the cutting insert the major cutting edges (22) are concave.