Indexable Cutting Insert With Wiper Geometry For 90° Shoulder Milling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cutting inserts with double negative cutting geometry, such as those disclosed in U.S. Patent No. 6,336,776, often result in adverse surface finish and high load on cutting edges due to acute angles and lack of gradual entry during 90° shoulder cutting operations.
Innovation Solution
A double-ended indexable cutting insert with a median plane and specific geometrical features, including primary cutting edges and wipers that form distinct angles, and a milling cutter design providing negative axial and radial relief angles, allowing for a true 90° cut with improved surface finish and reduced load on cutting edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the wiper is spaced apart from the insert corner by a transitional cutting edge and lies substantially in the plane of the major surface, then the insert can be mounted with negative axial rake and negative radial rake, but an acute angle is formed between the wiper and the work piece resulting in double negative cutting geometry which adversely impacts surface finish
Solution Approach 1:
Instead of having the wiper lie in the plane of the major surface (conventional configuration), the patent inverts the geometry by positioning the wiper such that it forms an obtuse angle with the work piece. The wiper is configured with positive rake angle while the primary cutting edge has negative rake angle, reversing the traditional approach to achieve better surface finish.
Solution Approach 2:
The patent changes the geometric parameters of the cutting edges. Specifically, it modifies the rake angles: the primary cutting edge has negative axial rake and negative radial rake, while the wiper has positive rake angle. This parameter change transforms the double negative cutting geometry into a mixed geometry that produces superior surface finish.
2Ease of manufacture
If the primary cutting edge is parallel to the axis of rotation (axial angle is zero), then the insert can be mounted with negative axial rake, but the entire cutting edge experiences the material all at once resulting in high load on cutting
Solution Approach 1:
The patent introduces a non-zero axial angle for the primary cutting edge, making the cutting process dynamic rather than static. This angular adjustment allows the cutting edge to gradually engage the material, distributing the load over time and reducing peak forces on the cutting edge while maintaining the negative rake mounting configuration.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A fully indexable square cutting insert (100) has four side surfaces (112A, 112B, 112C, 112D) connecting to two end surfaces. At the intersection of each side surface with an end surface is a primary cutting edge (120) which extends from an insert corner (106) and along a first side surface, in a downward direction towards a median plane (M). A wiper (122) extends from the same insert corner (106) and along an adjacent side surface, in an upward direction away from the medium plane (M), to rise above an abutment surface (108) of an associated end surface. The geometry of the cutting insert (100) and of the insert pocket in which the insert is seated are such that the primary cutting edge has a positive axial angle (helix), while the insert has an overall negative axial angle for providing axial clearance and an overall negative-radial angle for providing radial clearance.