Self-drilling screw asymmetrical tip geometry for chip removal
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Solution Overview
Problem
Self-drilling screws require high force to remove deformed material from the center of the drilling tip, leading to inefficient drilling and assembly processes in metal constructions.
Innovation Solution
The self-drilling screw design features asymmetrical tip geometry with cutting edge start points positioned opposite each other at a specific distance from the drilling tip center, allowing material removal through chip channels on both sides, enhancing chip removal and drilling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the start points of chip channels are arranged rotationally symmetrically on the drilling tip, then the structure is simple and manufacturing is easy, but material is squeezed in the center requiring high force
Solution Approach 1:
The patent applies asymmetry by positioning the start points of the chip channels at different radial distances from the drilling tip center. Specifically, the first start point is at a first radial distance and the second start point is at a second radial distance, where the radial distances are different. This asymmetric arrangement allows material to be directly removed through chip channels on both sides of the drilling tip center without being squeezed, thereby reducing the force required for material removal while maintaining manufacturing feasibility.
2Productivity
If material is removed through the center of the drilling tip, then drilling is efficient, but material must be squeezed and removed in a deformed state requiring high force
Solution Approach 1:
The asymmetric positioning of chip channel start points enables material to be evacuated directly through the chip channels from regions adjacent to the drilling tip center, rather than being compressed and forced through a central path. The first chip channel removes material from a first region and the second chip channel removes material from a second region, with both channels providing direct egress paths that eliminate the need for material deformation and high squeezing forces.
3Productivity
If the mean distance corresponds to 0.03 to 0.06 of the drilling tip diameter, then vibrations are optimized and chip removal is optimal, but the design becomes more complex
Solution Approach 1:
The patent applies local quality by specifying precise radial distance ranges for the chip channel start points relative to the drilling tip center. The first start point is positioned at a first radial distance and the second start point at a second radial distance, with these distances falling within optimized ranges (mean distance corresponding to 0.01 to 0.15 of the drilling tip diameter, preferably 0.03 to 0.06). This localized precision in positioning optimizes vibration characteristics and chip removal efficiency while maintaining overall geometric simplicity.
Data Source
AI summary
A self-drilling screw (10) has a thread-carrying shaft (11), a head (15) provided at one of its ends, and a drilling tip (12) provided at another of its ends, opposite the one end thereof, with the drilling tip (12) having first and second cutting edges (21, 22) and first and second chip channels (24, 25) associated with the first and second cutting edges (21, 22), respectively, beginning at first and second start points (26, 27) at the free end (14) of the drilling tip (12), and located on opposite first and second sides of the drilling tip (12), with the first and second start points (26, 27) being spaced from the center (Z) of the drilling tip (12) by a mean distance (X) corresponding to from 0.01 to 0.15 of the drilling tip diameter (D), and being spaced from each other by a maximum distance (Y) corresponding to from 0 to 0.8 of the mean distance (X).