Reciprocating Saw Blade Geometry for Faster, Lower-Vibration Cuts
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Solution Overview
Problem
Reciprocating saw blades with large tang angles experience reduced cutting speed, poor cut quality, increased vibration, and difficulty in tip cutting due to the increased angle, which also causes the cutting teeth to rub against the saw shoe during operation.
Innovation Solution
The reciprocating saw blade features an elongated blade body with a cutting edge comprising inclined, declined, and parallel cutting edge portions, where the inclined cutting edge portion rises at a first acute angle, the declined cutting edge portion falls at a second, greater angle, and the parallel cutting edge portion extends between them, optimizing the cutting edge geometry to facilitate more aggressive angles without increasing the tang angle, along with bump teeth to absorb impact loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the tang angle is increased to improve blade life, then blade life is improved, but cutting speed is reduced and vibration increases
Solution Approach 1:
The cutting edge is segmented into multiple portions (inclined, declined, and parallel) with different geometric characteristics. This segmentation allows each portion to perform different functions: the inclined portion enables aggressive cutting angles for improved blade life, while the parallel portion maintains stability and reduces vibration, thus resolving the contradiction between blade life and cutting speed
Solution Approach 2:
Different portions of the cutting edge are given different local geometries and properties. The inclined cutting edge portion has a specific angle configuration optimized for aggressive cutting, while other portions have different configurations optimized for stability and vibration reduction, allowing the blade to achieve both extended life and maintained cutting speed
2Duration of action of moving object
If the tang angle is increased to improve blade life, then blade life is improved, but cut quality deteriorates
Solution Approach 1:
The cutting edge is divided into distinct segments with different geometric properties. The inclined portion provides the aggressive angle for improved blade life, while the parallel portion maintains the stability needed for high-quality cuts, thus resolving the contradiction between blade life and cut quality
3Duration of action of moving object
If the tang angle is increased to improve blade life, then blade life is improved, but vibration increases
Solution Approach 1:
The cutting edge geometry is segmented into inclined and parallel portions. The parallel cutting edge portion acts as a stabilizing element that counteracts the vibration generated by the inclined portion's aggressive cutting action, thus resolving the contradiction between blade life and vibration
Solution Approach 2:
The parallel cutting edge portion functions as a counterbalancing element that offsets the vibratory effects produced by the inclined cutting edge portion, reducing overall blade vibration while maintaining the aggressive cutting geometry needed for extended blade life
4Duration of action of moving object
If the tang angle is increased to improve blade life, then blade life is improved, but tip cutting becomes difficult
Solution Approach 1:
The cutting edge is segmented into inclined and parallel portions, where the inclined portion enables aggressive cutting angles for improved blade life, while the parallel portion near the tip maintains the geometry needed for effective tip cutting operations
5Duration of action of moving object
If the tang angle is increased to improve blade life, then blade life is improved, but cutting teeth rub against the saw shoe
Solution Approach 1:
The cutting edge geometry is segmented into inclined and parallel portions. The parallel cutting edge portion creates a different engagement geometry with the saw shoe that prevents rubbing, while the inclined portion maintains the aggressive angle for improved blade life
Data Source
AI summary
A reciprocating saw blade includes an elongated blade body extending along a blade axis and having a rear end, a front end, a cutting edge having a plurality of teeth, a non-cutting edge opposite the cutting edge; and a tang coupled to the rear end and configured to be received in a blade holder of a powered reciprocating saw. The cutting edge includes inclined and declined cutting edge portions. The inclined cutting edge portion extends away from the blade axis and toward the front end at an acute first angle and extends from a first tooth to a second tooth. The first tooth is closer to the rear end and closer to the blade axis than the second tooth. The declined cutting edge portion extends toward the blade axis and toward the front end at an acute second angle that is greater than the first angle and extends from a third tooth to the first tooth. The first tooth is closer to the front end and closer to the blade axis than the third tooth.