Clearing Sawblade Tooth Geometry for Low-Kickback Cutting
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Solution Overview
Problem
Conventional hand-held clearing saws experience high energy consumption and kickback issues due to the breakdown of wood material into sawdust and the tendency of the sawblade to bounce out of the kerf during sawing, making the process cumbersome for users.
Innovation Solution
A circular sawblade designed for hand-held clearing saws featuring alternating rake and scoring teeth, where the rake teeth are optimized for cutting with a positive hook angle and the scoring teeth have a negative or zero hook angle, arranged in a specific repeating pattern to minimize energy consumption and control the feeding force, reducing kickback and self-feeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional clearing sawblades with standard tooth configuration are used, then the sawblade can cut through wood material, but the wood material is broken down into sawdust resulting in high energy consumption
Solution Approach 1:
The tooth configuration is segmented into three distinct types (scoring teeth, rake teeth, and relief teeth) that perform sequential functions. The scoring teeth first create incisions, then rake teeth remove material, and relief teeth clean the kerf. This segmentation prevents excessive wood breakdown into fine sawdust while maintaining cutting productivity.
Solution Approach 2:
The scoring teeth perform a preliminary action by creating incisions or slots in the wood material before the rake teeth engage. This preliminary scoring reduces the resistance for subsequent cutting operations and prevents the wood fibers from being violently torn apart, thereby reducing energy consumption while maintaining cutting efficiency.
2Reliability
If conventional clearing sawblades are used, then cutting can be performed, but the sawblade tends to kickback or bounce out of the kerf during sawing
Solution Approach 1:
Different portions of the sawblade periphery have different tooth qualities tailored to specific functions. The scoring teeth have a different hook angle and geometry compared to the rake teeth, which in turn differ from the relief teeth. This local differentiation ensures that each tooth type contributes to overall sawing stability in its specific role, preventing kickback while maintaining ease of operation.
Solution Approach 2:
The alternating sequence of scoring teeth, rake teeth, and relief teeth creates a periodic action pattern during rotation. This periodic engagement and release of wood material provides rhythmic cutting forces that stabilize the sawblade in the kerf, preventing bounce and kickback, thereby improving reliability and reducing user control effort.
3Productivity
If rake teeth with positive hook angle are used, then effective cutting of wood chips is achieved, but the sawblade is pulled into the tree creating feeding force that is uncomfortable for the user
Solution Approach 1:
The relief teeth with negative or zero hook angle act as a counterbalance to the feeding force generated by the rake teeth. As the relief teeth engage the wood material, they create a opposing force that counteracts the pulling effect of the rake teeth, thereby reducing the net feeding force and improving user comfort while maintaining cutting effectiveness.
Solution Approach 2:
Instead of having all teeth with positive hook angles that pull the blade into the material, the invention inverts the approach by incorporating relief teeth with negative or zero hook angles. These inverted teeth push back against the feeding force, creating a balanced cutting action that maintains productivity while significantly improving ease of operation and user comfort.
Data Source
Figure 1
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AI summary
A circular sawblade (10) for clearing sawing comprising a central opening (12) for releasable attachment to a clearing saw and a plurality of teeth (200, 300) and gullets (13) arranged alternating at the periphery of the sawblade (10) in a rotation direction (R), wherein the teeth (200, 300) comprises rake teeth (200) and scoring teeth (300), - wherein a hook angle (V) of the rake teeth (200) is greater than 0° and a hook angle (X) of the scoring teeth (311) is equal to, or less than, 0° and wherein the scoring teeth (300) alternatingly are set in opposite directions out from a symmetry plane (Z) of the sawblade (10).