Saw Blade Modal Frequency Control via Slot Geometry
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Solution Overview
Problem
Existing circular saw blade designs do not adequately address vibration issues within the operating frequency range, leading to significant blade vibration during cutting, which results in poor cutting feel, surface finish, and increased cut force.
Innovation Solution
A saw blade design featuring a circular metal disc with a central aperture and a specific configuration of fully enclosed body slots, including a first plurality of slots equally spaced from the center and a second plurality of slots radially outward with arcuate end sections and an undulating intermediate section, which eliminates modal frequencies within the operating frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional body slot designs are used for cooling, strain compensating, expansion and stiffness purposes, then the structural requirements are met, but vibration issues occur within the operating frequency range
Solution Approach 1:
The patent applies parameter changes by modifying the body slot geometry parameters - specifically using arcuate end sections with radii of curvature between 0.05-0.15 times the slot length, and undulating intermediate sections with 3-7 undulations. These parameter modifications shift the blade's natural frequencies away from the operating frequency range, eliminating resonance and vibration while preserving the slots' cooling and structural functions.
Solution Approach 2:
The patent employs curvature by designing body slots with arcuate end sections instead of straight ends, and incorporating undulating intermediate sections with multiple waves. This curvature in the slot geometry creates favorable stress distributions and modifies the blade's modal characteristics, reducing vibration within the operating frequency range while maintaining structural integrity.
2Ease of manufacture
If body slots are designed without considering vibration effects, then manufacturing and structural requirements are satisfied, but cutting performance deteriorates due to poor surface finish and increased cut force
Solution Approach 1:
The patent modifies the body slot parameters including length-to-width ratios of 5:1 to 20:1, specific arcuate end section radii, and undulation counts of 3-7 in intermediate sections. These parameter changes are designed to shift natural frequencies away from operating ranges, thereby reducing vibration-induced surface finish degradation and cut force variations while remaining manufacturable.
Solution Approach 2:
The patent converts the potentially harmful effect of body slots (which can create vibration) into a beneficial effect by carefully designing their geometry. The arcuate ends and undulating intermediate sections transform the slots from vibration sources into vibration-damping features, improving surface finish and reducing cut force while maintaining the original cooling and structural benefits.
Data Source
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AI summary
A saw blade (10) is provided including a circular metal disc (12) including a central aperture (14) and a plurality of teeth (16) spaced around a periphery of the circular metal disc. A first plurality of fully enclosed body slots (20) are generally equally spaced from a center of the circular metal disc (12) by a first distance (X1) and a second plurality of fully enclosed body slots (22) are each disposed directly radially outward from a respective one of the first plurality of body slots (20). The second plurality of slots (22) are generally equally spaced from the center of the circular metal disc (12) by a second distance (X2) greater than the first distance (X1). The saw blade design provides a blade with no modal frequencies in the operating frequency range.