Bottoming Tap and Chaser for Deep Blind Hole Thread Alignment
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Solution Overview
Problem
Deep blind holes pose challenges due to the need for multiple taps and chasers of varying lengths, tool misalignment, and debris buildup, which increase the risk of cross-threading and prolong the tapping or cleaning process.
Innovation Solution
The design of taps and chasers with a cylindrical receiver and integrally formed shaft allows for deeper hole access, precise alignment, and efficient debris removal, using novel helix angles and spiral flutes, along with a drive socket for standard ratchet driver compatibility, enabling use in confined spaces and reducing the need for multiple tool lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If long tools are used to access deep blind holes, then the tool can reach deeper holes, but alignment between the tool and hole is lost increasing the risk of cross-threading
Solution Approach 1:
The tool is divided into two functional segments: a long shaft for reaching deep holes and a separate alignment mechanism (cylindrical receiver) at the leading end. The receiver segment engages with the hole entrance to establish alignment, while the shaft extends the reaching capability, resolving the contradiction between length and precision.
Solution Approach 2:
The alignment function is performed preliminarily by the cylindrical receiver before the threading operation begins. The receiver establishes coaxial alignment with the hole entrance in advance, ensuring that subsequent threading actions maintain proper alignment even though the tool extends deeply into the hole.
2Length of moving object
If multiple taps and chasers of different lengths are maintained for deep blind holes, then deep hole access is enabled, but tool inventory complexity and cost increase
Solution Approach 1:
The tap design integrates multiple functions into a single tool: the cylindrical receiver provides alignment for deep holes, the shaft extends reaching capability, and the threading section performs the cutting function. This universal design allows one tool to handle deep blind holes of various depths, eliminating the need to maintain multiple specialized tools.
Solution Approach 2:
The tool components are nested hierarchically: the threading section is positioned on the shaft, which is positioned within the cylindrical receiver. This nested structure allows the tool to function as an integrated unit while maintaining the specialized functions of each component, enabling deep hole access without requiring separate specialized tools.
3Length of moving object
If long tools are used for deep blind holes, then deeper hole access is achieved, but clearance distance between driver and work piece increases limiting usage locations
Solution Approach 1:
The drive socket is positioned laterally offset from the tool's central axis, allowing the driver to engage with the tool at a location that minimizes the required clearance distance from the work piece. This dimensional repositioning of the drive interface enables the long tool to be operated in confined spaces where traditional end-driven tools would not fit.
4Manufacturing precision
If standard t-handle type drivers are used with self-aligning taps, then alignment is improved, but the tap cannot be used in deep blind holes
Solution Approach 1:
The alignment function and the reaching function are merged into a single integrated tool design. The cylindrical receiver provides alignment similar to self-aligning taps, while the extended shaft simultaneously provides the reaching capability for deep holes. This merging eliminates the need to choose between alignment precision and deep hole access.
Data Source
AI summary
A tap and chaser are provided each having a cylindrical tool receiver connected to a threading section by a shaft. The receiver and shaft are of diameters sufficiently small to enter the bore hole and distribute any off axis load onto a number of internal threads of the bore hole to dissipate loading. The threaded section includes a group of longitudinal flutes. Each of the lands of the threaded section includes a novel cutting face, tooth angle and rake angle to advantageously allow for threading deep blind holes.