Crushed-Thread Locking Bolt for Low-Torque Anti-Loosening
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Solution Overview
Problem
Conventional locking bolts with crushed ridge portions on threaded surfaces increase screwing torque and risk damage to internal thread flank surfaces, and fail to securely fasten at low torque settings, while also being prone to loosening under vibration.
Innovation Solution
A bolt with a crushed ridge portion formed on the entire or partial half-circumference of the regular threaded portion, advancing counterclockwise toward the shaft tip, with a controlled crushing amount of 7 to 22.5% of the ridge height, which reduces screwing torque and minimizes internal thread damage, and provides a loosening prevention effect by allowing the bulge to contact only the clearance flank surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crushed portions of ridges are formed on the peripheral surface of a regular threaded portion into a spiral shape, then loosening prevention effect is achieved, but screwing torque increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crushing amount of the ridge to be within 5-15 μm, and setting the spiral pitch between 0.5-2.0 times the thread pitch. These specific parameter ranges optimize the balance between achieving loosening prevention through interference with the internal thread's clearance flank surface and minimizing the increase in screwing torque, thereby resolving the technical contradiction.
2Reliability
If the bulge formed on the top of the ridge interferes with the flank surface of an internal thread, then loosening prevention is achieved, but the flank surface of the internal thread is greatly damaged
Solution Approach 1:
The patent controls the ridge crushing amount to be within 5-15 μm, which is sufficient to create a bulge that interferes with the clearance flank surface of the internal thread for loosening prevention, but small enough to avoid significant damage to the flank surface. This precise parameter control resolves the contradiction between achieving loosening prevention and preventing damage.
3Reliability
If a large bulge is formed to prevent loosening, then interference with internal thread is achieved, but screwing torque increases and target torque seating becomes impossible
Solution Approach 1:
By controlling the ridge crushing amount to 5-15 μm and the spiral pitch to 0.5-2.0 times the thread pitch, the patent creates a small bulge that provides loosening prevention through interference with the clearance flank surface while minimizing the increase in screwing torque. This allows the bolt to be seated at the target torque, resolving the contradiction between loosening prevention and manufacturing precision.
Data Source
AI summary
Provided is an invention relating to a bolt having a crushed portion of a ridge formed on a regular threaded portion of the bolt. The crushed portion of the ridge is set to have a height at which no screwing torque is generated when the bolt is screwed into an internal thread, and the crushed portion of the ridge is formed on an entire half-circumference or a partial half-circumference of the regular threaded portion so as to form a spiral shape that advances toward a shaft tip in a direction opposite to the ridge of the regular threaded portion when viewed from a head. The bolt of the present invention is used as a locking bolt or an earth bolt.