Thread Tapping Screw With Segmented Hard Cutting Elements
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Solution Overview
Problem
Thread-cutting screws face difficulties when screwing into hard materials like concrete or granite due to reaction forces that can cause the screw to twist off, making it challenging to screw in and potentially damaging the screw.
Innovation Solution
The screw features cutting elements with a cutting edge at the front end supported by a counter-screwing direction support section, made of harder material than the core, which acts like a chisel to cut a thread into the material, with pre-cutting and main cutting elements distributed along the thread to reduce mechanical load and wear, and a sawtooth-shaped cross-section for improved cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional thread-cutting screw is used to screw into hard materials, then the screw can cut a thread in the material, but the reaction forces cause the screw to twist off and be destroyed
Solution Approach 1:
The cutting thread is divided into multiple cutting elements distributed along the thread section, with each cutting element having a small bearing surface. This segmentation distributes the cutting forces across multiple points rather than concentrating them on a single large contact area, reducing the torque required and preventing the screw from twisting off
Solution Approach 2:
The cutting elements are made of material with higher hardness than the cylindrical core, creating a local quality difference. This allows the cutting edges to be sufficiently hard to cut through hard materials like concrete or granite, while the core maintains its structural integrity and resistance to twisting
2Productivity
If the cutting element has a large bearing surface on the inner wall of the borehole, then the screw can be supported better, but the cutting efficiency decreases and mechanical load increases
Solution Approach 1:
The cutting thread is segmented into multiple cutting elements, each with a small bearing surface on the inner wall of the borehole. This segmentation allows efficient cutting with reduced contact area per element, minimizing friction and mechanical load while maintaining cutting effectiveness through the distributed arrangement of hard cutting materials
Solution Approach 2:
The screw combines a cylindrical core made of one material with cutting elements made of a harder material. This composite structure allows the cutting edges to have high hardness for efficient cutting with minimal bearing surface, while the core provides structural support and torque resistance
3Duration of action of stationary object
If multiple cutting elements are used to distribute cutting work, then wear is reduced, but the device complexity increases
Solution Approach 1:
The cutting thread is divided into multiple cutting elements spaced along the thread section, with each element having a small bearing surface. This segmentation distributes the cutting workload across multiple elements, reducing wear on each individual element and extending service life, while the segmented structure is integrated into the thread form to avoid excessive complexity
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 facilitates secure attachment to the drill hole thread, simplifies torque loading, enhances engagement with the material, and improves cutting efficiency by distributing cutting work and reducing wear, while maintaining stability and robustness.
Implementation Method 1
each cutting element with at least one cutting edge (19), the cutting edge (19) along a screwing-in direction (2) at a front end of the at least one cutting element (11, 12) is arranged, wherein the cutting edge (19) is supported on the cutting thread (8) by a support section (20) that follows counter to the screwing-in direction (2)
Implementation Method 2
The at least one cutting element (11, 12) comprises a cutting material that has a higher hardness relative to a cylindrical core (5) of the thread-cutting screw (1)
Data Source
Figure 1
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AI summary
The screw (1) has a cylindrical core (5) with a central longitudinal axis (7). A cutting screw thread (8) extends along a cutting screw thread portion (Asg) and formed with the cylindrical core for cutting a bore hole screw thread in a material and provided with cutting screw thread diameter (Dsg). Cutting edge is located at leading ends of cutting elements (11, 12) along pivoting direction (2). The cutting edge is supported at the cutting screw thread by a supporting portion against the pivoting direction. A screw-in unit (18) acts on the screw with screw-in rotational torque.