Asymmetrical Thread Fastening Bolt for Concrete Drilling
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Solution Overview
Problem
Conventional concrete bolts with symmetrical threads experience high frictional resistance and difficulty in drilling vertically into concrete, leading to inefficient fastening and potential misalignment, resulting in a decreased fastening effect.
Innovation Solution
The fastening bolt features asymmetrical threads with different inclined angles and cutting grooves and recesses near the drilling portion, allowing for reduced resistance and stable vertical entry into the concrete, along with a dual-material shaft for enhanced drilling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetrical threads with equal inclined angles are used, then the thread structure is simple and easy to manufacture, but the frictional resistance during drilling is excessive and drilling efficiency is reduced
Solution Approach 1:
The patent applies asymmetry by designing threads with different inclined angles on opposite sides. The leading flank has a smaller inclined angle (10°-20°) to reduce friction and facilitate easier entry into concrete, while the trailing flank has a larger inclined angle (30°-45°) to provide sufficient engagement. This asymmetric configuration directly resolves the contradiction by improving drilling efficiency without significantly complicating manufacturing.
Solution Approach 2:
The patent applies local quality by varying the thread parameters at different locations along the shaft. Threads near the drilling portion have optimized smaller inclined angles to reduce initial friction, while threads farther away have larger inclined angles for better engagement. This localized variation in thread geometry allows the structure to adapt to different functional requirements along its length, resolving the contradiction between manufacturing simplicity and drilling efficiency.
2Force
If more torque is exerted to overcome frictional resistance, then the drilling force increases, but the shaft swings or enters aslant causing misalignment
Solution Approach 1:
The asymmetric thread design with different inclined angles creates a self-aligning effect. The smaller leading angle reduces friction in the direction of drilling, allowing the bolt to enter smoothly without requiring excessive torque. This prevents the shaft from swinging or becoming misaligned, thus resolving the contradiction between applying sufficient drilling force and maintaining drilling alignment.
3Device complexity
If threads with small gradient inclined angles are used, then the thread structure is symmetrical and simple, but the drilling resistance is excessive and fastening effect is reduced
Solution Approach 1:
The patent uses asymmetric thread angles where the leading flank has a smaller angle (10°-20°) to reduce friction and facilitate entry, while the trailing flank has a larger angle (30°-45°) to ensure firm engagement and reliable fastening. This asymmetric design improves fastening effect without significantly increasing structural complexity, as it only modifies the thread geometry rather than adding complex components.
Solution Approach 2:
The patent applies different thread parameters at different locations: threads near the drilling portion have smaller inclined angles for easier entry, while threads farther away have larger inclined angles for better engagement and reliability. This localized variation optimizes both the drilling process and the final fastening effect without requiring a completely complex overall structure.
4Speed
If excessive torque is applied to force threads into the wall, then the drilling speed increases, but the shaft enters aslant and cannot drill vertically
Solution Approach 1:
The asymmetric thread configuration with different inclined angles on opposite flanks creates a self-centering effect during drilling. The smaller leading angle reduces friction and allows the bolt to enter smoothly at the correct angle, while the larger trailing angle provides sufficient engagement. This design enables faster drilling speeds without sacrificing verticality or alignment precision.
Data Source
AI summary
A fastening bolt includes a shaft defining a central axis, a head, a drilling portion, and first threads alternating with second threads. The first threads and the second threads have different outer diameters. Each first thread has a trailing surface facing the head and inclined to a line perpendicular to the central axis by a trailing angle and a leading surface facing the drilling portion and inclined to the line by a leading angle. The trailing angle is smaller than the leading angle to build an asymmetrical form. Some threads near the drilling portion form respective cutting grooves and recesses thereon. Each cutting groove is formed by walls with different lengths and opened at an angle which does not exceed 90 degrees. The bolt breaks the workpiece quickly by the cutting grooves and recesses. The asymmetrical first threads help enter the workpiece quickly and attain a firm engagement therewith.