Bolt and method of mfg. bolt

Abstract

A bolt, comprising a coarse thread screw part with a pitch of (P) formed in an area ranging from the tip part to the specified part of a bolt shaft part and a fine thread screw part with a pitch of (P) (p=P / n, where n is the integer of 2 or more) formed by overlapping on the coarse thread screw part at least through the overall length of the coarse thread screw part of the bolt shaft part or through the area ranging from the tip part of the bolt shaft part to the specified part of the coarse thread screw part, whereby the bolt low in cost, mass-producible, excellent in synchronization of screw crests, high in compressive strength and shearing strength, making hard a nut threaded thereto to be loosened even if a large vibration load is applied thereto, and excellent in tightening force can be provided.

Description

technical field [0001] The present invention relates to a bolt with anti-loosening function provided with a coarse thread portion and a fine thread portion and a manufacturing method thereof. Background technique [0002] In recent years, various bolts with anti-loosening function and their manufacturing methods have been researched and developed. [0003] As a prior art, for example, in Japanese Invention Patent Publication No. 51033 / 1999 (hereinafter referred to as No. 1 publication), it is disclosed that "a groove that cuts off both side flanks of the thread is provided along the crest of the thread." , and use the vicinity of the root of the thread tooth as a self-locking thread formed by a wide root recess in the shape of digging from the extension surface of the tooth flank to the inside." [0004] In addition, in Japanese Invention Patent Publication No. 254072 / 1999 (hereinafter referred to as Publication No. II), it is disclosed that "on the surface of a flat plate,...

AI Technical Summary

Problems solved by technology

[0006] (1) In the technology described in the No. I bulletin, since grooves are formed along the crests of the thread teeth, and the vicinity of the root of the thread teeth is dug out, if the thread teeth are to be thinned, there will be a lack of cutting. Shear stress, lack of durability issues

[0007] (2) In the technology described in the No. 1 bulletin, when the nut is threaded, the thread teeth are always in a state of elastic deformation, and the mechanical strength decreases with time. Therefore, it also brings lack of compressive stress, lack of durability and poor safety. good question

[0008] (3) The technology described in the Publication No. II does not take into account the relationship between the durability and strength of the thread part, the synchronization of the thread teeth, etc. caused by the difference in the pitch of the right-hand thread and the left-hand thread.

Therefore, the problem is that, compared to the thread teeth of one thread, the root of the other thread is helically set with no effect, and there will also be parts where the thread teeth may be damaged, resulting in weakened compressive stress and shear elasticity. The durability is lacking, and the thread connection force is reduced at the same time; in addition, the synchronization of the thread teeth of the manufactured right-hand thread and left-hand thread becomes worse, the truncation part of the thread teeth increases, and the mechanical strength becomes lower, and it is found that the defective product is visually very difficult

[0009] (4) When the lead angle of the threaded part threaded with the first nut installed on the bolt is smaller than the lead angle of the threaded part threaded with the second nut installed later, relative to the rotation of the same angle Generally speaking, the moving distance of the second nut is greater than that of the first nut, thus, problems of easy looseness, lack of screw connection force and poor safety are brought about

[0010] (5) When the pitch of the fine thread portion is only made smaller than the pitch of the coarse thread portion, it is obvious that the fine thread portion will be irregularly formed on the coarse thread portion; in addition, the coarse thread portion will also appear At the position where the thread teeth are cut at the top, the pattern of the fine thread part formed by overlapping on one pitch of each coarse thread part cannot show regularity, and the outer diameter of the bolt shows a network pattern, which cannot be a product. A structure with high thread pitch and low thread thread appears, and the loss of mechanical strength becomes larger compared with the standard thread

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