Helical Broach Cutting Layout for Accurate Gullet Profiles
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Solution Overview
Problem
Helical broaches experience excessive cutting and forming errors due to chip interference, leading to inaccurate tooth profiles and increased broach body length and weight, which complicates handling.
Innovation Solution
A broach design with a high-feed cutting section having a cutting depth of 0.15 mm to 0.30 mm per cutting edge, reducing chip-flowing angle and preventing excessive cutting, combined with a low-feed cutting section at the front to avoid shock loads, allowing for a shorter and lighter broach body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of cutting edges in the roughing edge is increased to achieve desired gullet depth, then the cutting depth per cutting edge can be reduced, but the length and weight of the broach body increase significantly
Solution Approach 1:
The patent changes the cutting depth parameter from the conventional 0.07-0.08mm to a larger value of 0.15-0.30mm in the high-feed cutting section. This parameter change allows achieving the desired gullet depth with fewer cutting edges, reducing the broach body length from approximately 2m to a shorter length, thereby reducing weight and improving ease of handling while maintaining cutting precision through the optimized chip flow control
2Ease of operation
If the cutting depth per cutting edge is increased to reduce the number of cutting edges, then the broach body length and weight are reduced, but chip interference causes excessive cutting and forming errors
Solution Approach 1:
The patent applies different cutting depth parameters to different sections of the broach. The front side uses conventional small cutting depth (0.07-0.08mm) to avoid shock loads, while the rear side uses large cutting depth (0.15-0.30mm) to reduce the number of cutting edges. This local differentiation resolves the contradiction by allowing large cutting depth benefits while mitigating chip interference issues through section-specific optimization
Solution Approach 2:
The broach is divided into two distinct sections: a front side with conventional cutting depth for stable initial cutting, and a rear side with high-feed cutting section for efficient material removal. This segmentation allows each section to optimize its cutting parameters, preventing chip clogging in the high-feed section while maintaining overall tooth profile accuracy
3Manufacturing precision
If conventional small cutting depth is used to avoid chip interference, then tooth profile accuracy is maintained, but the broach body length must be increased to achieve desired gullet depth
Solution Approach 1:
The patent implements a parameter change strategy by increasing the cutting depth from conventional 0.07-0.08mm to 0.15-0.30mm in the high-feed cutting section. This parameter change reduces the number of cutting edges needed from approximately 2m worth to a shorter configuration, achieving the desired gullet depth with reduced broach body length while controlling chip flow to maintain accuracy
Data Source
Figure 1
Figure 2~3
Figure 4(a)~4(d)
AI summary
This broach includes a broach body (1) having a shaft shape and a cutting edge section (4) in which cutting edges (5) protrude and are arranged in a longitudinal direction on an outer circumference of the broach body (1). The cutting edge section (4) includes, in the order from a front side of the broach body (1), an circumference cutting section (6) in which an outer diameter of each of the cutting edges (5) sequentially increases rearward, and a tooth thickness cutting section (7) in which a thickness of each of the cutting edges (5) sequentially increases from the cutting edges (5) at a rear end of the circumference cutting section (6) toward the rear side. At least a rear end portion of the circumference cutting section (6) is a high-feed cutting section (6A) in which the cutting depth per cutting edge is set in a range of 0.15 mm or more and 0.30 mm or less, since an outer diameter of each of the cutting edges (5) sequentially increases toward the rear side. Accordingly, highly accurate broaching can be performed by preventing tooth profile accuracy degradation of gullets formed in a workpiece, and improvement of ease of handling and power saving of a broaching machine can be achieved by shortening of the broach body.