Cutting Insert With Variable Rake Angles For Fracture Resistance
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Solution Overview
Problem
Cutting inserts with arcuate cutting edges face increased cutting resistance and risk of fracture when machining difficult-to-cut materials, such as heat-resistant alloys and high hardness materials, especially as the depth of cut increases.
Innovation Solution
A cutting insert design featuring an arcuate major cutting edge and a minor cutting edge with a smaller curvature radius, along with inclined rake portions that reduce contact area and distribute thrust force, preventing chatter vibration and enhancing cutting edge strength by varying rake angles along the cutting edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an arcuate cutting edge is used to improve cutting edge strength and reduce chip thickness, then cutting edge strength is improved, but cutting resistance increases and the cutting edge becomes liable to fracture when the depth of cut increases
Solution Approach 1:
The cutting insert applies local quality by providing different rake angles at different locations along the cutting edge. The first rake portion has a larger rake angle to reduce cutting resistance at the entry point, while the second rake portion has a smaller rake angle to provide structural support and reduce the likelihood of fracture at the deeper cutting region. This spatial variation in rake angle allows the cutting edge to simultaneously achieve low cutting resistance and high strength.
Solution Approach 2:
The invention changes the geometric parameters of the cutting insert by introducing a variable rake angle configuration along the cutting edge. The rake angle transitions from a larger angle in the first rake portion to a smaller angle in the second rake portion. This parameter change enables the cutting edge to adapt to varying cutting conditions, reducing cutting resistance where needed while maintaining strength in critical regions.
2Productivity
If the depth of cut is increased to improve productivity, then productivity is improved, but generated chips become thicker and cutting resistance increases leading to potential cutting edge fracture
Solution Approach 1:
The variable rake angle configuration provides local quality optimization for deep cutting operations. The first rake portion with the larger rake angle specifically addresses the high cutting resistance zone created by increased depth of cut, while the second rake portion maintains structural integrity. This allows the cutting insert to handle deeper cuts with reduced cutting resistance and lower risk of fracture.
Solution Approach 2:
By changing the rake angle parameter along the cutting edge, the invention enables the cutting insert to effectively process deeper workpieces. The transition from a larger rake angle to a smaller rake angle allows the system to maintain acceptable cutting resistance levels even when the depth of cut is increased, thereby improving productivity without sacrificing cutting edge strength.
Data Source
AI summary
A cutting insert, a cutting tool and method of manufacturing a machined product. The cutting insert includes: upper and lower surfaces; a side surface; a cutting edge; and a rake portion on the upper surface. The cutting edge includes major and minor cutting edges that are convex toward outside of the main body portion. The minor cutting edge has a curvature radius smaller than a curvature radius of the major cutting edge. The rake portion is inclined and approaches the lower surface as moving from the major cutting edge toward inside of the main body portion and is located along the major cutting edge. An inclination angle of the rake portion becomes smaller as moving from a part continuous with one end of the major cutting edge toward a part continuous with center of the major cutting edge.