Circular Saw Blade Transverse Offset for Cutting Line Alignment
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Solution Overview
Problem
Hand-held circular saws with adjustable cutting depth often experience misalignment between the scoring and sawing cutting lines due to the circular shape of the saw blade, leading to ineffective pre-scoring and potential tearing of the workpiece surface, especially when manufacturing tolerances or bearing play cause the saw blade to deviate from the intended parallel alignment.
Innovation Solution
The saw blade is transversely offset relative to the base part when the cutting depth is exceeded, ensuring that the scoring and sawing cutting lines coincide, with the offset amount compensating for alignment discrepancies, allowing for precise adjustment and automatic compensation during the plunging movement, thereby preventing tearing of the workpiece edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the saw blade is not aligned exactly parallel to the working direction due to manufacturing tolerances or bearing play, then the saw blade can be easily manufactured and assembled, but the cutting line deviates from the pre-scored line causing surface tearing
Solution Approach 1:
The patent applies preliminary action by pre-setting the saw blade at a specific angle relative to the working direction before operation. The blade is deliberately tilted by a predetermined angle (typically 1-3 degrees) during manufacturing or initial setup, so that when the saw is used for both scoring and cutting, the blade automatically follows the pre-scored line even with bearing play or manufacturing tolerances. This preliminary angular adjustment compensates for potential alignment errors during actual operation.
2Ease of operation
If the saw blade is tilted by a clearance angle to prevent jamming, then the saw blade runs smoothly during cutting, but the cutting line shifts relative to the pre-scored line
Solution Approach 1:
The patent applies asymmetry by intentionally tilting the saw blade at a specific angle (clearance angle of 1-3 degrees) relative to the working direction. This asymmetric positioning ensures that the blade does not run exactly parallel to the working direction but at a deliberate angle, which prevents the blade from jamming during cutting while maintaining consistent alignment with the pre-scored line throughout the cutting process.
3Ease of manufacture
If the saw blade bearing has relatively large play, then the bearing is more tolerant and easier to manufacture, but the cutting line varies with cutting depth causing ineffective pre-scoring
Solution Approach 1:
The patent applies preliminary action by pre-setting the saw blade at a specific angle relative to the working direction during manufacturing or initial setup. This predetermined angular positioning compensates for bearing play variations during operation, ensuring that the blade maintains consistent alignment with the pre-scored line across different cutting depths, thereby making the pre-scoring effective.
4Ease of operation
If the saw blade is adjusted to a low cutting depth for pre-scoring, then the workpiece surface is only scratched superficially, but the cutting line deviates from the actual saw cut line
Solution Approach 1:
The patent applies asymmetry by tilting the saw blade at a specific clearance angle (1-3 degrees) relative to the working direction. This asymmetric angular positioning ensures that both the pre-scoring operation at low cutting depth and the subsequent cutting operation at full depth follow the same cutting line, eliminating deviation between the scored line and the actual cut line.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The saw has a machine part (15) comprising a propelled saw blade (17), and an adjusting device (19) for adjusting i.e. pivoting, the saw blade relative to a base part (13) for adjusting desired cutting depth. The adjusting device displaces the saw blade transverse to a working direction (A) with respect to the base part around a present amount during exceeding a predetermined cutting depth i.e. pre-scratch cutting depth. The amount of transverse displacement is independent of measure of exceeding the predetermined cutting depth.