Circular Saw Blade Tips with Negative Rake Angles
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Solution Overview
Problem
Conventional circular saw blades experience tip damage and brazed portion breakage due to stress concentration when cutting steel materials, particularly when cutting tubular welded steel pipes, as chips and weld beads accumulate and get caught in the cutting edges.
Innovation Solution
The circular saw blade design features tips with a first rake face at a negative angle and a second rake face that is radially inward, inclined at a negative angle relative to the first rake face, with a slanted basal portion fitting into a recessed installation portion on the base metal, allowing chip discharge and reducing stress on the borderline between the tip and base metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the second rake face is formed at a positive angle or on a virtual line connecting the rotation center and cutting edge to secure a large gullet, then chip discharge is improved, but stress concentrates on the borderline between the second rake face and base metal causing tip damage and brazed portion breakage
Solution Approach 1:
The patent changes the geometric parameter of the second rake face from a positive angle or radial alignment to a negative angle relative to the virtual line connecting the rotation center and cutting edge. This parameter change allows the second rake face to extend further radially outward, creating a larger gullet volume for chip accumulation while simultaneously moving the borderline between the second rake face and base metal away from the high-stress concentration zone, thereby preventing tip damage and brazed portion breakage
2Productivity
If chips and weld beads accumulate inside the steel pipe during cutting, then cutting progresses, but the accumulated material gets caught in cutting edges causing stress concentration and tip breakage
Solution Approach 1:
The patent preliminarily shapes the second rake face with a negative angle to create adequate gullet space before cutting begins. This preliminary geometric configuration ensures that as cutting progresses and chips accumulate, the material has sufficient space to be contained and directed away from the cutting edge, preventing catch and subsequent tip breakage while maintaining continuous cutting productivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces the likelihood of tip damage and brazed portion breakage by dispersing stress and enhancing the strength of the joint between the tip and base metal, enabling efficient cutting of steel materials without tip detachment or damage.
Implementation Method 1
the second rake face of the tip allows discharge of chips or the like from the gullet in the outer peripheral direction, while reducing the load applied on the borderline between the tip and the base metal
Implementation Method 2
it is possible to reduce the stress applied on the borderline facing the gullet between the second rake face of the tip and the base metal by providing a slant that inclines on the positive side relative to the second rake face with the second rake face
Implementation Method 3
each tip is bonded on a stepwise installation portion formed on a tooth body in the peripheral portion of the base metal by brazing the back surface, which faces in the direction opposite the rotational direction, and the bottom surface, which faces the rotation center
Data Source
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AI summary
[OBJECT] To make tips less likely to be damaged. [MEANS OF REALIZING THE OBJECT] A tip (30) has a first rake face (40) that is contiguous with a cutting edge (32), and a second rake face (42) that is contiguous with the first rake face and faces a gullet (16) provided in front of the tip (30) in the rotational direction, wherein the second rake face (42) has a radially inward inner edge that is in contact with the outer peripheral edge of the base metal (12) that defines the gullet (16). The second rake face (42) is formed such that the second rake angle (θ2), which is formed between a first reference line (L1) drawn from the rotation center of the circular saw blade to the cutting edge (32) and a second reference line (L2) that passes through the radially inward inner edge along the second rake face (42), is a negative angle.