WO2002053926A1

WO2002053926A1 - Threaded fastener with lock structure

Info

Publication number: WO2002053926A1
Application number: PCT/KR2001/000016
Authority: WO
Inventors: Hong Soon Park
Original assignee: Hong Soon Park
Priority date: 2000-12-28
Filing date: 2001-01-05
Publication date: 2002-07-11
Also published as: KR20020055224A

Abstract

The object of this invention is to provide a threaded fastener with a lock structure. During a process of manufacturing of such threaded fasteners, the lock structure is formed on the threads of either the bolt (10) or the nut (20) by partially compressing the threads (2a,20a) to compress the crests of the threads (2a,20a) after forming the threads on the nut or bolt, thus partally thickening the threads due to the compression. Therefor, the maximum frictional force is formed between the compressed threads of one of the nut and bolt and the normal threads of the other without leaving any clearance between the threads (2a,20a) when tightening the nut and bolt together, thus creating frictional contact at the junction of the compressed and normal threads and preventing an undesired rotating action of the bolt (10) or the nut (20) relative to the other in every direction.

Description

THREADED FASTENER WITH LOCK STRUCTURE

Technical Field

The present invention relates, in general, to a threaded fastener with a lock structure, such as nuts and bolts, and, more particularly, to a threaded fastener with a lock structure maintaining a high-tension locking state of the fastener for a desired lengthy period of time and accomplishing a desired locking effect of the fastener, the lock structure being formed on the threads of either a nut or a bolt by compressing the threads partially to compress the crests of the threads and form compressed parts after forming the threads through a tapping process or a dieing process during a manufacturing process of such fasteners, thus partially thickening the threads due to the compression and forming the maximum frictional force between the compressed threads of one of the nut and bolt and the normal threads of the other without leaving any clearance between the compressed and normal threads when tightening the nut and bolt together, and maintaining the desired locking operational effect of the fastener for a desired lengthy period of time.

Background Art

As well known to those skilled in the art, threaded fasteners consisting of nuts and bolts and typically used for assembling or fastening a variety of structural materials, such as steel and wood, or parts of machines together as a single body, are required to keep their locking state for a desired lengthy period of time so as to accomplish a desired integrated position of the structural materials except for the case of consciously disassembling the integrated structural materials into parts. Particularly in the case of precision machines fabricated with a plurality of parts assembled or fastened together, the fastening strength of such nuts and bolts is the most important factor determining the operational safety and processing precision of the machines.

Most machines, with a variety of parts assembled as single bodies by such nuts and bolts, are continuously impacted and vibrated, particularly at their fastened parts, due to frictional force and pressure applied thereto during operation or power transmission. Such impact and vibration gradually makes the nuts and bolts loosened.

For example, such impact and vibration continuously applied to the fastened parts of a machine increases the reverse directional torque of unidirectionally tightened nuts and bolts, thus making the nuts or bolts undesirably rotate in the reverse direction so as to be loosened. In conventional nuts and bolts, the threads are designed to allow a clearance when a bolt is tightened to a nut, and so the externally threaded shank of the bolt is allowed to undesirably move relative to the internally threaded bore of the nut when the tightened nut and bolt are impacted or vibrated regardless of the intensity of the impact or vibration. In such a case, the frictional force acting at the junction of the engaging threads of the nut and bolt is reduced, and so the tightened nut and bolt are undesirably loosened and fail to effectively fasten the parts of the machine together. When the nuts and bolts are loosened to lose their fastening force as described above, the machine is reduced in its processing precision, operational safety, operational reliability and durability. It is thus necessary to often and repeatedly repair the machine to perform correction or error or replace old parts with new ones. In the prior art, the problems of such an undesired loosening of tightened nuts and bolts may be overcome by designing the thread's spiral directions of nuts and bolts to oppose the rotating direction of a target machine, or by use of spring washers with nuts and bolts. However, the nuts and bolts with such thread's spiral directions are problematic in that they are limitedly used with machines having threaded holes agreeing with the spiral directions of the bolts. On the other hand, the spring washers are problematic in that they increase the cost and are gradually reduced in their spring force, and so they fail to maintain desired operational function for a lengthy period of time. In addition, a bolt, with the tip axially slit into two parts to elastically hold the bolt at a tightened position in the same manner as expected from a conventional wedge, has been proposed and used. However, the bolts with such slit tips complicate the production process of bolts and are difficult to fasten or unfasten, thus being inconvenient to users.

Therefore, it is necessary for the threaded fasteners consisting of nuts and bolts to be provided with a simple lock structure capable of maintaining the firm locking state of the nuts and bolts regardless of impact and vibration while allowing the nuts and bolts to be easily tightened or loosened in the conventional manner as desired. " ^'

Disclosure of the Invention

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a threaded fastener, which is provided with a lock structure maintaining a high-tension locking state of fastener for a desired lengthy period of time and accomplishing a desired locking effect of the fastener, the lock structure being formed on the threads of either a nut or a bolt by partially compressing the threads to compress the crests of the threads and form compressed parts, thus forming maximum frictional force between the compressed threads of one of the nut and bolt and the normal threads of the other without leaving any clearance between the threads when tightening the nut and bolt together, and freely adapted to penetrate bolts or tap bolts, and which is tightened or loosened in the conventional manner and is effectively used for firmly fastening structural materials together or parts of a machine together.

In order to accomplish the above object, the present invention provides a threaded fastener consisting of a nut or a bolt, comprising: a lock structure formed on the threads of either the nut or the bolt by partially compressing the threads to compress the crests of the threads and form compressed parts, thus partially thickening the threads due to the compression and forming the maximum frictional force between the compressed threads of one of the nut and bolt and the normal threads of the other without leaving any clearance between the threads when tightening the nut and bolt together so as to create frictional contact at the junction of the compressed and normal threads and preventing an undesired rotating action of the nut or bolt relative to the other in every direction.

Brief Description of the Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a perspective view of an externally threaded fastener or a bolt with a lock structure in accordance with the primary embodiment of the present invention;

Fig. 2 is a view, showing the profile and operational theory of the lock structure formed on the bolt of the present invention; Fig. 3 is a sectional view of a bolt with a lock structure of this invention tightened to a hole having normal internal threads;

Fig. 4 is a sectional view of an internally threaded fastener or a nut with a lock structure in accordance with the second embodiment of the present invention when a bolt with normal threads is tightened to the nut; and Figs. 5a, 5b and 5c are perspective views of three bolts with different lock structures according to different embodiments of the present invention, in which:

Fig. 5 a shows a bolt having a longitudinal lock structure formed on the threads along an axial direction of the bolt;

Fig. 5b shows a bolt having a plurality of short lock structures formed on the threads along the axial direction of the bolt to form a linear arrangement; and Fig. 5c shows a bolt having a plurality of short lock structures formed around the threads of the bolt to form an annular arrangement.

Best Mode for Carrying Out the Invention

Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

Fig. 1 is a perspective view of an externally threaded fastener or a bolt with a lock structure in accordance with the primary embodiment of the present invention. Fig. 2 is a view, showing the profile and operational theory of the lock structure formed on the bolt of this invention. As shown in the drawings, the lock structure of this invention may be adapted to a conventional threaded fastener, that is, a conventional bolt 10 or a conventional nut 20. The bolt 10 consists of a head 1 and a threaded shank 2. When the lock structure of this invention is adapted to a threaded fastener consisting of nut 10 and bolt 20, the lock structure may be preferably formed on the threads of one of the nut and bolt. In the present invention, the lock structure may be freely formed on conventional threaded fasteners regardless of the spiral directions of the internal or externals threads 2a or 20a, the size of the fasteners, the kinds of the fasteners, such as tap bolts or penetrate bolts, or the use of the fasteners. That is, the lock structure of this invention may be freely formed on all kinds of conventional threaded fasteners.

The lock structure of this invention is formed on the threads 2a or 20a of either a bolt 10 or a nut 20 by partially compressing the threads to compress the crests of the threads 2a or 20a and form compressed parts 2b or 20b, thus partially thickening the threads 2a or 20a due to the compression. That is, due to the compressed parts 2b or 20b, the thickness of the threads 2a or 20a is increased to Li while reducing the pitch L₂. Fig. 3 is a sectional view of a bolt 10 with a lock structure of this invention tightened to a hole having normal internal threads. In order to allow the bolt 10 to be firmly tightened to the internally threaded hole, the external threads 2a of the shank 2 of the bolt 10 are partially and axially compressed at their crests, and so each of the compressed threads 2a is thickened at its opposite sides due to the compression, thus having a increased thickness of _\. In the present invention, a plurality of lines of compressed parts 2b may be axially formed on the external threads 2a of the shank 2 at diametrically opposite positions. Alternatively, the compressed parts 2b may be axially formed on the external threads 2a of the shank 2 to form a zigzag arrangement in place of the linear arrangement. As a further alternative, the compressed parts 2b may be formed on the external threads 2a of the shank 2 to form a step arrangement in place of the zigzag or linear arrangement.

From Fig. 2 showing the profile and operational theory of the lock structure formed on the bolt of this invention, it is noted that the desired operational function of the lock structure may be accomplished when the pitch L is reduced to a desired dimension due to the compression of the threads 2a or 20a. when the lock structure of this invention is formed on a conventional locking bolt used for a holed sheet to a fixed surface having a internally threaded hole, it is necessary to compress the external threads of the bolt's shank 2 at a position spaced apart from the bolt head at an interval corresponding to the thickness of the holed sheet, thus allowing the compressed external threads of the bolt's shank 2 to firmly engage with the normal threads of the internally threaded hole of the fixed surface. In such a case, it is necessary to determine the proper number of the compressed parts 2b capable of allowing the bolt to be tightened and loosened without difficulty.

Therefore, when the bolt is tightened to a nut as shown in Fig. 3, the compressed external threads 2a of the bolt with the reduced pitch L₂ formed by the increased thickness Li tightly engage with the normal internal threads 20a of the nut without leaving any clearance α between the threads 2a and 20a, thus forming the maximum frictional force between the compressed threads 2a and the normal threads 20a. When the threaded shank 2 of such a bolt is inserted into the internally threaded hole of the nut, frictional contact is created at the junction of the compressed and normal threads 2a and 20a at every lead with the reduced pitch L₂, thus preventing an undesired reversed rotating action of the bolt relative to the nut. Therefore, the bolt normally maintains its fastening force for a desired lengthy period of time irrespective of impact or vibration from a machine, except for the case of a conscious loosening of the bolt.

Fig. 4 is a sectional view of an internally threaded fastener or a nut with a lock structure in accordance with the second embodiment of the present invention when a bolt with normal threads is tightened to the nut. Figs. 5a, 5b and 5c are perspective views of three bolts with different lock structures according to different embodiments of the present invention, in which: Fig. 5a shows a bolt having a longitudinal lock structure formed on the external threads along the axial direction of the bolt, Fig. 5b shows a bolt having a plurality of short lock structures formed on the external threads along the axial direction of the bolt to form a linear arrangement, and Fig. 5c shows a bolt having a plurality of short lock structures formed around the external threads of the bolt to form an annular arrangement.

Different from the bolt of Fig. 1 with the compressed parts 2b partially and axially formed on the externally threaded shank 2 at a position spaced apart from the head, the compressed part 2b of Fig. 5a is axially and continuously formed on the entire length of the externally threaded shank 2 of the bolt, thus increasing the fastening force of the bolt. This bolt is preferably used as a locking bolt, and is more preferably used for locking a sheet having an internally threaded hole to a fixed surface. In the bolt of Fig. 5b, a plurality of compressed parts 2b having a short length are axially and intermittently formed on the external threads to form a linear arrangement. This bolt is easily tightened to an internally threaded hole and forms frictional force acting on the junction of the compressed threads of the bolt and the normal threads of the internally threaded hole. In the bolt of Fig. 5c, a plurality of compressed parts 2b having a short length are regularly formed around the external threads 2a of the shank 2 after determining proper positions within a lead to be compressed. The bolt of Fig. 5c accomplishes the same fastening effect as the bolts of Figs. 5a and 5b. In the present invention, the size of the compressed part 2b, such as its width and length, is preferably determined so as to form a desired pitch capable of creating the maximum frictional force between the engaging threads of the nut and bolt. However, it should be understood that an excessive size of the compressed part 2b is not proper for accomplishing the desired operational function of this invention.

Industrial Applicability

As described above, the present invention provides a threaded fastener with a lock structure. In the present invention, the lock structure is formed on a conventional threaded fastener, that is, a nut or a bolt, and maintains a high-tension locking state of the fastener for a desired lengthy period of time, and accomplishes a desired locking effect of the fastener. The lock structure is formed on the threads of a nut or a bolt by at least partially compressing the threads to compress the crests of the threads and form compressed parts, thus forming maximum frictional force between the compressed threads of one of the nut and bolt and the normal threads of the other without leaving any clearance between the compressed and normal threads when tightening the nut and bolt together. Due to the lock structure, the threaded fastener of this invention forms firm and reliable fastening force. In the threaded fastener of this invention, the internal or external threads have a normal shape at positions except for the compressed parts, thus having a normal clearance at the junction of the engaging threads except for the positions around the compressed parts. It is thus possible for a user to easily remove the bolt from the nut in a conventional manner when necessary. In the present invention, the lock structure may be freely formed on conventional threaded fasteners, such as nuts or bolts, regardless of the spiral directions of the threads, the size of the fasteners, the kinds of the fasteners, or the use of the fasteners. The threaded fasteners of this invention can be thus produced and marketed as independent items. This threaded fastener is also easily produced through a simple process and is easily used by people, and so the fastener has high productivity and high market competitiveness.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A threaded fastener consisting of a nut or a bolt, comprising: a lock structure formed on threads of either the nut or bolt by at least partially compressing the threads to compress the thread's crests and form compressed parts, thus partially thickening the threads due to the compression and forming maximum frictional force between the compressed threads of the nut or bolt and normal threads of the other without leaving any clearance between the compressed threads and the normal threads when tightening the nut and bolt together so as to create frictional contact at the junction of the compressed and normal threads and preventing an undesired rotating action of the nut or bolt relative to the other in every direction.