Rotary Cutting Tool Rake Face for Controlled Chip Segmentation
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Solution Overview
Problem
Conventional rotary cutting tools face issues when machining hard, brittle materials, such as ceramic and cemented carbide, as they generate fine chips that cause edge chipping, increase cutting resistance, and lead to reduced tool lifespan and machining efficiency.
Innovation Solution
A rotary cutting tool with a concavely provided rake face and a level-difference surface on the chip discharge groove formation surface, which forces chips to be divided into an appropriate size, reducing edge chipping and damage, and extending tool service life by controlling chip size and improving machining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard film with some degree of thickness is formed on the surface of a tool for machining a hard, brittle material, then wear resistance is improved, but roundness is formed on the edge tip, sharpness decreases, and cutting resistance increases
Solution Approach 1:
The invention divides the chip into multiple segments using a level-difference surface (step structure) on the rake face. This segmentation prevents the chip from forming a continuous bridge across the cutting edge, thereby reducing the biting effect and cutting resistance while maintaining the hard film coating for wear resistance.
Solution Approach 2:
The invention introduces a level-difference surface (step structure) that adds a vertical dimension to the rake face geometry. This dimensional change creates a step that interrupts the chip flow path, forcing the chip to break and reducing its ability to bite into the cutting edge, thus lowering cutting resistance without compromising the hard film's protective function.
2Quantity of substance
If the feed amount per cutting edge is increased to enlarge discharged chips, then chip size is improved, but brittle fractures easily occur in hard, brittle materials
Solution Approach 1:
The level-difference surface segments the chip into smaller portions, allowing effective chip control at lower feed amounts. This segmentation prevents excessive chip size and the associated risk of brittle fracture while still achieving adequate chip evacuation and reduced biting effects.
Solution Approach 2:
The invention changes the geometric parameters of the rake face by introducing a level-difference surface with specific height and position parameters. This geometric parameter change enables effective chip breaking at lower feed amounts, allowing machining of hard brittle materials without causing brittle fractures while still producing manageable chip sizes.
3Productivity
If the rotational speed (cutting speed) of the cutting tool is increased to improve machining efficiency, then productivity is improved, but wear of the cutting edge is easily promoted
Solution Approach 1:
The level-difference surface segments the chip, reducing the continuous contact between the chip and cutting edge. This reduces the biting effect and thermal load on the cutting edge, allowing higher rotational speeds without excessive wear, thereby improving productivity while maintaining tool service life.
Solution Approach 2:
The invention converts the potentially harmful continuous chip contact into a beneficial segmented chip structure. The level-difference surface causes the chip to break and reduce its biting effect, transforming the harmful continuous rubbing into beneficial intermittent contact, which reduces wear and enables higher cutting speeds for improved productivity.
4Object-affected harmful factors
If chips are increased in size to reduce fine chip generation, then edge chipping is suppressed, but the cutting tool or workpiece could be damaged by biting into chips during cutting
Solution Approach 1:
The level-difference surface segments the chip into controlled portions, preventing both excessive chip size and continuous chip bridges. This segmentation reduces the biting effect on the cutting edge and workpiece while still suppressing edge chipping by preventing fine chip generation and continuous chip contact.
Solution Approach 2:
The invention optimizes the geometric parameters of the level-difference surface (height, position, and dimensions) to achieve the right balance. The parameters are designed to break chips into appropriate sizes that suppress edge chipping without being so large as to cause biting damage to the tool or workpiece, converting the harmful effect of large chips into a beneficial controlled chip structure.
Data Source
Figure 1
Figure 2~3
Figure 4~5(b)
AI summary
It is an object of the present invention to provide a rotary cutting tool that can divide chips at an appropriate size, suppress the incidence of edge chipping and damage attributed to chips to the cutting tool and a workpiece, extend the tool service life with regard to the machining of hard, brittle materials, and improve machining efficiency. The rotary cutting tool includes a hard coat film 3 coated onto a tip end section of a tool body 1 having a chip discharge groove 2. A rake face 6 is concavely provided in a cutting edge-side chip discharge groove formation surface 4 constituting the chip discharge groove 2 of the tool body 1, from a cutting edge 5 and along the cutting edge 5.