Anti-seizing nut with incomplete thread for oblique bolt insertion
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Solution Overview
Problem
Existing anti-seizing solutions for nuts fail to effectively prevent seizing when a bolt with a general shape is inserted obliquely, often requiring specialized bolt shapes or pilot portions that increase costs and resource inefficiency.
Innovation Solution
An anti-seizing nut design featuring an incompletely threaded female portion at the bolt insertion end with an internal diameter larger than (d+d1)/2 but smaller than the male-threaded external diameter, preventing forced engagement and allowing the bolt to tilt back to a correct posture during insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pilot portion is formed on the bolt to correct insertion posture, then the posture correction effect is improved, but a small-diameter female-threaded portion is formed between the pilot portion and nominal female-threaded portion, causing seizing
Solution Approach 1:
The invention extracts the posture correction function from the bolt's pilot portion and transfers it to the nut's incompletely threaded female portion. By removing the thread ridge in the first axial direction at the front end of the female-threaded portion, the nut itself provides the guidance function, eliminating the need for a pilot portion on the bolt and avoiding the creation of a small-diameter female-threaded portion that causes seizing.
Solution Approach 2:
Instead of modifying the bolt with a pilot portion to achieve posture correction, the invention inverts the approach by modifying the nut with an incompletely threaded female portion. The thread ridge removal at the front end of the female-threaded portion creates a guidance structure that corrects bolt insertion posture without generating harmful seizing conditions.
2Ease of operation
If the pilot portion is formed in a long size to improve posture correction, then the inclination correction is enhanced, but the pilot portion becomes a useless portion that does not contribute to fastening force, increasing costs and resource waste
Solution Approach 1:
The female-threaded portion of the nut serves dual functions: it provides the primary fastening function through thread engagement and simultaneously provides posture correction through the incompletely threaded section at its front end. By removing the thread ridge in the first axial direction, the same structural element that engages the bolt for fastening also guides the bolt insertion, eliminating the need for a separate pilot portion and avoiding resource waste.
3Object-generated harmful factors
If thread ridge end portions are cut out to prevent seizing, then seizing is prevented, but both bolt and nut must be formed in particular shapes, limiting versatility
Solution Approach 1:
The invention extracts the seizing prevention function from bolt modification and implements it solely in the nut by removing the thread ridge at the front end of the female-threaded portion. This allows the use of standard general-shape bolts without requiring any special modifications to the bolt, while still achieving effective seizing prevention through the incompletely threaded female portion.
Data Source
AI summary
Provided is a nut into which a bolt (10) including a male-threaded portion with a male-threaded external diameter d and a male-threaded core diameter d1 is screwed, wherein a bolt insertion side end of a female-threaded portion (21) formed in a nut body (20) is provided with an incompletely threaded female portion (22) that is formed by one to three pitches so that an internal diameter dimension D is larger than (d+d1)/2 and is smaller than the male-threaded external diameter d. Accordingly, even when the bolt is screwed into the nut in the inclination direction, the bolt may be rotated about a contact surface with respect to the incompletely threaded female portion (22), and hence seizing may be prevented.