Threaded-Tip Holesaw Assembly for Low-Force Plug Removal
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Solution Overview
Problem
Holesaws face challenges with user fatigue due to required axial bias, poor runtime performance with cordless power tools, and difficulty in removing waste material, especially when compared to self-feed drill bits.
Innovation Solution
A holesaw assembly with a hollow cup design, featuring cutting inserts with specific geometric configurations and a pilot bit with a threaded tip that allows for minimal axial bias and increased cordless runtime, including features like hook angles, bevel angles, and offset distances to facilitate easier plug removal and improved cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional holesaw is used, then it forms a solid plug of waste material, but it requires a large amount of axial bias to drive the holesaw through the workpiece, causing user fatigue
Solution Approach 1:
The pilot bit is segmented into multiple functional zones: a threaded tip portion for self-feeding, a transition portion, and a cutting head portion. This segmentation allows different sections to perform different functions, with the threaded tip providing self-feeding action that eliminates the need for manual axial bias while the cutting head forms the solid plug waste material.
Solution Approach 2:
The threaded tip portion of the pilot bit provides self-feeding action that automatically advances the pilot bit and holesaw through the workpiece without requiring manual axial bias. The threads engage the workpiece material and propel the cutting tool forward, making the system self-service in terms of feed force generation.
2Productivity
If a conventional holesaw is used with a cordless power tool, then it can drill holes, but it has poor runtime performance
Solution Approach 1:
The threaded tip portion of the pilot bit provides self-feeding action that automatically advances the pilot bit and holesaw through the workpiece without requiring manual axial bias. The threads engage the workpiece material and propel the cutting tool forward, making the system self-service in terms of feed force generation.
Solution Approach 2:
The invention changes the geometric parameters of the pilot bit, specifically incorporating a threaded tip with specific thread pitch, diameter, and depth ratios. These parameter changes optimize the self-feeding action to reduce motor load and energy consumption, thereby extending battery runtime while maintaining productivity.
3Object-generated harmful factors
If a conventional holesaw is used, then it removes a solid cylindrical plug, but it is difficult to remove the plug of waste material from the holesaw
Solution Approach 1:
The pilot bit is segmented into multiple functional zones: a threaded tip portion for self-feeding, a transition portion, and a cutting head portion. This segmentation allows different sections to perform different functions, with the threaded tip providing self-feeding action that eliminates the need for manual axial bias while the cutting head forms the solid plug waste material.
Solution Approach 2:
Instead of trying to push the plug out axially, the invention uses the threaded tip to screw the plug out in reverse. The threads that were used to feed the pilot bit into the workpiece are now used to extract the plug by rotating the pilot bit in reverse, making plug removal as easy as reversing the drilling motion.
4Ease of operation
If a self-feed drill bit is used, then it throws small chips over a wide area, but it is less messy than holesaws
Solution Approach 1:
The holesaw assembly combines two functions: the pilot bit with threaded tip for self-feeding and centering, and the holesaw for cutting the large diameter hole and forming a solid plug. This multi-functionality allows the system to achieve the clean solid-plug removal of a holesaw while incorporating the self-feeding mechanism that reduces the need for manual pressure.
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 holesaw assembly significantly reduces user fatigue, increases cordless runtime by up to 162% compared to existing designs, and enhances cutting speed and efficiency, allowing for more holes to be drilled per battery charge while maintaining hole quality.
Implementation Method 1
pilot bit with a threaded tip that allows for minimal axial bias
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A holesaw assembly (10) includes a holesaw (12) and a pilot bit (16). The holesaw includes a hollow cup (18) defining a center axis. The cup has a round base perpendicular to the center axis and a peripheral wall coupled to and extending axially forward of the base to a peripheral edge at a free end of the wall. The pilot bit (16) is received in the holesaw (12) along the center axis. The pilot bit (16) has a shaft received in the base, a cutting head coupled to a front end of the shaft, and an at least partially threaded tip (82) coupled to a front end of the cutting head. The holesaw (12) is free of any radial cutting elements disposed inside the cup (18) between the drill bit and the peripheral wall of the cup (18).