Indexable Rotating Tool Tip Centering and Fastening
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Solution Overview
Problem
Existing thread forming taps with detachable tips face challenges in achieving high centering accuracy and strength due to smaller cross-sectional areas, leading to variability in tool life and potential sudden failures, and inadequate cooling performance results in reduced tool life and risk of tool damage.
Innovation Solution
A thread forming tap design where the screw shaft is screwed into the body's screw hole for screw-fastening, with a restraining portion fitting into a hole for precise centering, and cooling fluid is discharged through the body and radial holes to ensure effective cooling, enhancing both fastening strength and tool longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tip is detachably attached to a body by screw-fastening using an attachment screw, then the tool allows for replaceability and flexibility, but high accuracy of centering between the body and tip becomes difficult to achieve and the coupling portion may fail suddenly due to load torque
Solution Approach 1:
The attachment structure is divided into three functional elements: a screw shaft for fastening, a restraining portion for centering, and a coupling portion for torque transmission. This segmentation allows each element to perform its specific function optimally - the screw shaft provides strong attachment, the restraining portion ensures precise centering, and the coupling portion transmits torque reliably.
Solution Approach 2:
The restraining portion acts as an intermediary element between the screw shaft and the body's restraining hole. It provides a dedicated centering function that mediates the alignment between the tip and body, ensuring high centering accuracy without compromising the replaceability provided by the screw-fastening mechanism.
2Volume of moving object
If the cross-sectional area of components is reduced, then the tool becomes more compact and flexible, but sufficient strength cannot be achieved leading to sudden failure
Solution Approach 1:
The screw shaft is designed with non-uniform cross-sectional area, being larger at the base end where it connects to the restraining portion and smaller at the leading end. This local quality variation allows the structure to have sufficient strength at critical locations while maintaining overall compactness. The restraining portion also has a cross-sectional area larger than the screw shaft's leading end to provide additional strength where needed.
3Device complexity
If cooling fluid is discharged obliquely forward from branch paths, then the structure is simplified, but sufficient cooling performance is not achieved causing tool welding and crack formation
Solution Approach 1:
The cooling fluid discharge direction is changed from oblique forward discharge to upward discharge toward the outer circumferential side of the tip. This dimensional change in discharge direction allows the cooling fluid to effectively reach the machining point without requiring complex branching structures, thereby achieving sufficient cooling performance while maintaining structural simplicity.
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
This design achieves high centering accuracy, increased strength, and stable tool life by applying compressive stress on the screw shaft, while effective cooling prevents tool damage and extends the tool's operational life.
Implementation Method 1
a screw shaft 24 disposed on the tip 14 is screwed into a screw hole 26 disposed in the body 12
Implementation Method 2
applying compressive stress on the screw shaft
Implementation Method 3
a restraining portion 40 of the tip 14 is fitted into a restraining hole 38 disposed in the body 12
Implementation Method 4
cooling fluid is discharged through the body and radial holes to ensure effective cooling
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
By screwing a threaded shaft (24) provided on a tip (14) into a threaded hole (26) provided on a body (12), the tip (14) is detachably installed on the body (12). Additionally, a restraining part (40) of the tip (14) is fitted into a restraining hole (38) provided in the body (12) and the body (12) and the tip (14) are positioned to be concentric with the shaft center (O). As a result, a separate installation screw is unnecessary and the tool is configured from two parts, the body (12) and the tip (14). Therefore, high centering precision is easily obtained. Additionally, the cross-sectional areas of the respective parts increase and strength increases, variation in tool life is limited, and excellent tool life can be stably obtained. Moreover, because the surface (24f) of the tip of the threaded shaft (24) is pressed to adhere closely to the bottom surface (26f) of the threaded hole (26) and the tip (14) is fixed to the body (12) to form a unit, a compressive stress acts on the threaded shaft (24) and the tip (14) can be fastened to the body (12) with a higher fastening strength than when a tensile stress is in operation.