Cutting Insert Rake Surface Design for Chip Discharge
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Solution Overview
Problem
Cutting inserts with upwardly inclined rake surfaces at the end parts of the cutting edge face increased frictional resistance and poor chip discharge performance due to increased friction between chips and the rake surface, making it difficult to stably discharge thin chips.
Innovation Solution
A cutting insert design featuring a first rake surface inclined downward at the middle part of the cutting edge and paired second rake surfaces inclined upward with concave parts, reducing cutting resistance and enhancing chip discharge stability by guiding chips into a stable discharge direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rake surface at the end parts of the cutting edge is inclined upward, then chip discharge direction is stabilized, but frictional resistance between chips and rake surface increases
Solution Approach 1:
The patent applies different inclination characteristics to different regions of the rake surface. The second rake surfaces at the end parts are inclined upward to stabilize chip discharge direction, while the first rake surface at the middle part is inclined downward to reduce frictional resistance. This local differentiation resolves the contradiction by optimizing each region for its specific function.
2Strength
If the rake surface is inclined upward to enhance chip rigidity through wave shape deformation, then chip discharge performance improves, but cutting resistance increases
Solution Approach 1:
The patent creates wave-shaped chip deformation locally at the end parts through upwardly inclined second rake surfaces, while the middle part with downwardly inclined first rake surface maintains low cutting resistance. This spatial differentiation allows chip rigidity enhancement only where needed without increasing overall cutting resistance.
3Stability of the object's composition
If the rake surface area in contact with chips is increased to improve chip control, then chip discharge stability improves, but abrasion of the insert increases
Solution Approach 1:
The patent concentrates the chip control function in the upwardly inclined second rake surfaces at the end parts, while the middle part with downward inclination minimizes contact area to reduce abrasion. This localized approach maintains chip discharge stability through strategic positioning rather than extensive contact area.
Data Source
Figure 1(a)~1(d)
Figure 2
Figure 3
AI summary
A cutting insert having low cutting resistance and excellent chip discharge performance is provided. The cutting insert 1 according to an embodiment of the present invention includes an upper surface 2, a lower surface 3, a side surface, and a cutting edge 5 disposed between an intersection of the upper surface 2 and the side surface 4. The upper surface 2 includes a rake surface continuous with the cutting edge 5. The rake surface includes a first rake surface 21 which is located correspondingly to a middle part of the cutting edge 5, and is parallel to a horizontal plane L including the intersection or is inclined downward as the first rake surface separates from the cutting edge 5, and a pair of second rake surfaces which are located on both sides of the first rake surface 21 and are inclined upward as the second rake surfaces separate from the cutting edge 5, and which include concave parts 2231b and 221c. A cutting tool including the cutting insert, and a method of manufacturing a machined product using the cutting tool are also provided.