Acute Angle Cutting Insert Prevents Shifting
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Solution Overview
Problem
Conventional indexable ball-end mills with positive-type cutting inserts experience cutting insert displacement due to cutting resistance, leading to accuracy deterioration and potential breakage, as the side surface adjacent to the cutting edge forms an obtuse angle with the tool body, causing the insert to be pulled out or shifted.
Innovation Solution
A cutting insert design featuring a side surface that intersects the first surface at an angle less than 90°, with an inclined surface on the second surface to resolve cutting resistance into perpendicular and parallel forces, increasing friction resistance and preventing undesirable motion, and a tool body with three insert seats for mounting the cutting inserts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a positive-type cutting insert with a side surface forming an obtuse angle with the bottom surface is used, then the cutting insert can be mounted with the cutting edge involved in cutting, but the cutting insert is pulled out of the side surface of the insert seat and lifted or shifted due to cutting resistance
Solution Approach 1:
The invention changes the symmetric obtuse angle configuration to an asymmetric acute angle configuration. The side surface portion (4b) is designed to intersect the first surface (2) at an angle less than 90 degrees, creating an asymmetric geometry that generates a beneficial moment to counteract the harmful lifting moment caused by cutting resistance. This asymmetric design prevents the cutting insert from being pulled out or shifted during cutting operations.
Solution Approach 2:
The invention changes the critical geometric parameter from an obtuse angle (greater than 90 degrees) to an acute angle (less than 90 degrees). This parameter change fundamentally alters the mechanical behavior of the cutting insert during cutting, transforming the moment generated by cutting resistance from a harmful lifting force to a beneficial stabilizing force that presses the cutting insert against the insert seat.
2Ease of operation
If the side surface adjacent to the cutting edge forms an obtuse angle with the bottom surface, then the cutting insert can be mounted to the insert seat, but a large load is applied to the mounting screw causing potential breakage
Solution Approach 1:
The asymmetric acute angle design of the side surface portion (4b) creates a mechanical advantage that redistributes the load. The acute angle geometry generates a moment that naturally presses the cutting insert against the insert seat, reducing the burden on the mounting screw and preventing excessive loads that could cause screw breakage.
Solution Approach 2:
The acute angle configuration acts as a mechanical counterweight system. The geometry itself generates a counter-moment that opposes the lifting moment caused by cutting resistance, effectively counterbalancing the forces that would otherwise be transmitted to the mounting screw, thereby protecting it from excessive loads.
3Reliability
If the cutting insert is fixed with a mounting screw, then the cutting insert can be held in position, but the mounting screw is subjected to large loads and may break
Solution Approach 1:
The acute angle geometry of the side surface portion (4b) performs a preliminary stabilizing action before cutting begins. The geometry is designed to automatically generate a stabilizing moment during cutting operations, preemptively counteracting lifting forces before they can cause displacement or excessive loading on the mounting screw.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively suppresses undesirable motion of the cutting insert, enhancing fixability and cutting accuracy by increasing friction resistance between the cutting insert and the tool body, thereby preventing lifting or shifting during cutting.
Implementation Method 1
increasing friction resistance between the cutting insert and the tool body
Data Source
AI summary
A cutting insert has top and bottom surfaces opposing each other and a side surface connecting them. A part of an intersecting ridge between the top and side surfaces functions as a cutting edge. On the side surface, a side surface portion adjacent to the intersecting ridge portion opposing the cutting edge intersects the top surface at an acute angle. At least on a part of a bottom surface, an inclined surface gradually approaching the top surface with increasing distance from a side surface portion on a side opposite to a cutting edge is formed. This allows a part of the cutting resistance to act on the side surface portion. As a result, friction resistance between the side surface portion and the side surface of an insert seat becomes larger, thereby suppressing a shifting of the cutting insert when cutting.