Band Saw Blade Gullet Design for Chip Curling and Stress Reduction
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Solution Overview
Problem
Band saw blades face issues with chip clogging and early body breakage due to high friction heat and stress concentration at the gullet bottom, particularly when cutting ductile materials like stainless steel at high speeds.
Innovation Solution
A band saw blade design featuring an arc-shaped chip curler on the rake surface that forms chips into small rolled shapes before they contact the gullet bottom, combined with a dent portion to increase the curvature radius of the gullet bottom and a non-contact surface to prevent chip adhesion, dispersing stress concentration and enhancing chip discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed cutting is performed on ductile materials like stainless steel, then cutting efficiency is improved, but chip adhesion to the rake surface occurs due to high friction heat
Solution Approach 1:
The chip curler portion is positioned to act on the chip before it reaches the gullet bottom, forming a curled shape in advance. This preliminary action prevents the chip from adhering to the rake surface by changing its trajectory and shape before adhesion can occur, thereby resolving the contradiction between high-speed cutting efficiency and chip adhesion prevention
Solution Approach 2:
The high friction heat that causes chip adhesion is converted into a beneficial effect by using the heat-softened chip material to form tighter curls through the chip curler portion. The heat makes the chip more pliable, allowing it to form compact curled shapes that are easier to discharge, thus transforming the harmful thermal effect into a useful shaping mechanism
2Ease of operation
If a chip curler protrudes from the tooth tip to improve chip curling, then chip discharge is improved, but the curvature radius of the gullet bottom becomes smaller causing stress concentration
Solution Approach 1:
Instead of only protruding the chip curler forward, the invention adds a rearward extension component that curves backward toward the gullet bottom. This dimensional change creates a dual-effect structure: the forward portion curls the chip for easy discharge, while the backward extension increases the gullet bottom curvature radius to reduce stress concentration, thereby resolving both chip discharge and blade durability requirements
Solution Approach 2:
The chip curler portion is designed with different local geometries: the forward section has a smaller radius for effective chip curling, while the rearward extension section has a larger radius for stress distribution. This local quality differentiation allows each portion to fulfill its specific function - chip curling and stress reduction respectively - resolving the contradiction between chip discharge ease and blade strength
3Shape
If the gullet bottom has a small curvature radius to accommodate the chip curler, then chip curling is effective, but stress concentration occurs at the gullet bottom
Solution Approach 1:
The chip curler portion is segmented into two functional zones: a front section with small curvature radius for effective chip curling, and a rear extension section with large curvature radius for stress reduction. This segmentation allows each zone to optimize its local function without compromising the other, resolving the contradiction between chip curling effectiveness and stress concentration
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
The design effectively prevents chip clogging and early body breakage by forming small, easily dischargeable chips and reducing stress concentration at the gullet bottom, thereby improving cutting precision and blade durability.
Implementation Method 1
the chip C generated along a rake surface of the cutting blade ST is easily attached to the rake surface due to a high friction heat on the rake surface
Implementation Method 2
dispersing stress concentration and enhancing chip discharge
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
A band saw blade includes multiple saw teeth having a straight tooth (5) and right and left set teeth (7A, 7B, 9A, 9B), and also includes a gullet portion (11) provided between the saw teeth. A rake surface (13) of each of the saw teeth is provided with a chip curler portion (17) formed into an arc shape at an entire range of approximately 90° to form a chip generated at the time of cutting a work into a small rolled shape before the chip comes into contact with a bottom portion (15) of the gullet portion (11). A chip non-contact surface (19) to be kept out of the contact with the chip curler portion (17) and the bottom portion (15) of the gullet portion (11), and a dent portion (21) is formed between the chip non-contact surface (19) and the gullet bottom portion (15), the dent portion (21) recessed from the chip non-contact surface (19) in an opposite direction to a moving direction of the band saw blade in order to increase radius (R) of a concave curved surface constituting a back side of the gullet bottom portion (15). A flat portion for dispensing stress concentration is provided at an innermost portion of the gullet portion (11).