Cutting Insert Curved Edge Geometry for Surface Smoothness
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Solution Overview
Problem
Existing cutting inserts with negative axial rake angles risk deteriorating the smoothness of machined surfaces due to protrusion of secondary sub cutting edges, limiting the effectiveness of machining processes.
Innovation Solution
A cutting insert design featuring a second flat cutting edge that remains parallel to the machined surface over its entire length, even with a negative axial rake angle, utilizing both inclined and curved cutting edges to ensure high smoothness and elongate the major cutting edge for increased depth of cut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a negative axial rake angle is used for the cutting insert, then the cutting insert can be attached to the tool holder, but the secondary sub cutting edge protrudes toward the front end of the tool, deteriorating the smoothness of the machined surface
Solution Approach 1:
The patent applies local quality by creating a localized curved portion on the side surface that specifically modifies the geometry of the second flat cutting edge. This curved portion causes the second flat cutting edge to slope downward from the front end toward the rear end, making its lowermost point positioned at the front end. This localized geometric modification ensures that when the cutting insert is attached with a negative axial rake angle, the second flat cutting edge remains substantially parallel to the machined surface, preventing protrusion and maintaining surface smoothness while allowing proper attachment.
2Manufacturing precision
If the second flat cutting edge is made parallel to the machined surface with negative axial rake angle, then high smoothness is achieved, but the cutting edge length may be reduced
Solution Approach 1:
The patent applies spheroidality (curvature) by introducing a curved portion on the side surface that generates a sloped configuration for the second flat cutting edge. This curved geometry allows the cutting edge to follow a downward slope from front to rear, positioning its lowermost point at the front end. This curved design enables the second flat cutting edge to maintain parallelism with the machined surface while preserving an adequate cutting edge length, thus achieving both high surface smoothness and sufficient cutting edge length simultaneously.
3Productivity
If the major cutting edge is elongated to increase depth of cut, then larger depth of cut is achieved, but the cutting edge may become more vulnerable to damage
Solution Approach 1:
The patent applies local quality by creating a specific curved portion on the side surface that modifies only the local geometry of the second flat cutting edge, while the rest of the cutting insert structure remains unchanged. This localized modification allows the second flat cutting edge to slope downward and position its lowermost point at the front end, enabling it to function as an effective cutting edge that contributes to depth of cut while maintaining structural integrity and resistance to damage.
Data Source
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Figure 3(a)~3(b)
AI summary
A cutting insert of the present invention includes an upper surface; a lower surface; a side surface which is connected to the upper surface and the lower surface and has a first side surface and a second side surface in order; and a cutting edge includes a first flat cutting edge and a first major cutting edge in order in an intersection region of the first side surface and the upper surface, and has a second flat cutting edge and a second major cutting edge in order in an intersection region of the second side surface and the upper surface. The first side surface includes a first chamfered side surface with a curved shape, a first corner side surface with a planar shape, and a first major side surface in order. The second side surface includes a second chamfered side surface with a curved shape, a second corner side surface with a planar shape, and a second major side surface in order. The intersection region of the second side surface and the upper surface includes a first intersection region of the second chamfered side surface and the upper surface, and a second intersection region of the second corner side surface and the upper surface. The second flat cutting edge is located from the first intersection region to the second intersection region, and has a lowermost portion in the first intersection region in a side view. A cutting tool including the cutting insert, and a method of manufacturing a machined product using the cutting tool are also provided.