WO2008020706A1

WO2008020706A1 - Method for manufacturing half nut with steel plate

Info

Publication number: WO2008020706A1
Application number: PCT/KR2007/003900
Authority: WO
Inventors: Kwon-Hee Kim
Original assignee: Kwon-Hee Kim
Priority date: 2006-08-14
Filing date: 2007-08-14
Publication date: 2008-02-21
Also published as: KR100867765B1; KR20080015327A

Abstract

Disclosed is a method of manufacturing a half-nut made of a steel plate in which a female screw is formed at an inner surface of a U-shaped steel plate member. In the method, if the steep plate having a predetermined size is prepared, the steel plate is cut to form a flat first preform including a first member perform. The first member preform of the flat first perform is subjected by primarily bending, to form a second preform including a second member perform. The second member preform includes a semicircular curved portion and a pair of inclined plane portions extending obliquely from distal ends of the semicircular curved portion. Simultaneous with the primary bending, an inner surface of the semicircular curved portion is subjected to coining, to form a female screw at the inner surface of the semicircular curved portion. The female screw includes a plurality of screw threads and screw valleys arranged alternately with each other. Then, the inclined plane portions of the second perform is subjected to secondary bending, to form a half-nut including a pair of flat plane portions extending parallel to each other from the distal ends of the semicircular curved portion. With the press forming such as bending and coining, etc., the female screw can be simply and precisely formed at the inner surface of the U- shaped steel plate member, resulting in an improved productivity and reduced manufacturing costs.

Description

METHOD FOR MANUFACTURING HALF NUT WITH STEEL

PLATE

Technical Field

[1] The present invention relates to a method of manufacturing a half- nut made of a steel plate, and more particularly, to a method of manufacturing a half-nut made of a steel plate, in which a female screw is formed at an inner surface of a U-shaped steel plate member. Background Art

[2] Various shapes and structures of bolts and nuts have been developed and widely used as fastening elements for a variety of machines, appliances, devices, etc. Generally, bolts and nuts are made of various materials including metals, nonmetals, synthetic resins, etc., and in particular, metals are mainly used in the manufacture of fastening elements requiring a mechanical rigidity. In the case of a metal nut, a female screw thereof is processed by means of a tap, for the sake of mass production. Tapping is performed by machine tools such as a lathe, drilling machine, etc.

[3] Meanwhile, steel plates, such as a hot-rolled steel plate, a cold-rolled steel plate, a molten-zinc-plated steel plate, a stainless steel plate, etc., are processed into products, having various structures and shapes required by design, by shearing, cutting, punching, bending, forming, compression, etc. Disclosure of Invention Technical Problem

[4] A conventional tapping technology has many difficult problems to process a female screw at an inner surface of a U-shaped or semicircular steel plate member. Firstly, to press a steel plate to form a U-shaped steel plate member and subsequently, to process a female screw at the steel plate member, the steel plate member should be first clamped to a fixture in a machine tool, and thereafter, a female screw should be formed at an inner surface of the steel plate member by tapping. This causes an excessive dead time, resulting in a low productivity and high manufacturing costs.

[5] Secondly, although the steel plate member has a minimum thickness to fulfill a desired mechanical rigidity within a range allowed by press-forming, it is difficult to process the precise dimensional female screw at the inner surface of the thin steel plate member due to a processing tolerance of the machine tool, and this increases the occurrence of defective products.

[6] Thirdly, when the U-shaped steel member constitutes a part of a product, it is difficult to clamp the steel plate member to the fixture. Also, since a steel plate press machine and a female screw tapping machine must be installed in series to achieve an improved productivity and reduced manufacturing costs, there is a problem of a heavy investment for facilities and equipment. Technical Solution

[7] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of manufacturing a half-nut made of a steel plate, in which a female screw can be simply formed at an inner surface of a U-shaped steel plate member by press-forming including bending and coining, etc.

[8] It is another object of the present invention to provide a method of manufacturing a half-nut made of a steel plate, in which a female screw is formed at an inner surface of a steel plate member by press-forming, to achieve an improved productivity and reduced manufacturing costs.

[9] It is yet another object of the present invention to provide a method of manufacturing a half-nut made of a steel plate, in which a precise dimensional female screw can be formed at an inner surface of a steel plate member.

Advantageous Effects

[10] As described above, with a method of manufacturing a half- nut made of a steel plate, a female screw can be simply formed at an inner surface of a U-shaped steel plate member by press-forming including bending and coining, etc. Accordingly, the present invention can achieve an improved productivity and reduced manufacturing costs. Further, according to the present invention, a precise dimensional female screw can be formed at the inner surface of the steel plate member. Brief Description of the Drawings

[11] 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:

[12] FIG. 1 is a perspective view illustrating the configuration of a half nut, applied to a fixture, according to the present invention;

[13] FIG. 2 is a sectional view taken along the line II- II of FIG. 1;

[14] FIG. 3 is an exploded view of the half- nut shown in FIG. 1;

[15] FIG. 4 is a partially enlarged sectional view taken along the line IV-IV of FIG. 3;

[16] FIG. 5 is a flow chart illustrating a half- nut manufacturing method according to the present invention;

[17] FIG. 6 is a perspective view illustrating the configuration of a steel plate to form the half nut and a first preform obtained from the steel plate according to the present invention;

[18] FIGS. 7 and 8 are sectional views illustrating the configuration of a first die and a first punch used for a primary bending and coining of the first preform included in the half-nut manufacturing method according to the present invention;

[19] FIGS. 9 and 10 are sectional views illustrating the formation of a second preform by the primary bending and coining using the first die and the first punch in the half- nut manufacturing method according to the present invention; and

[20] FIGS. 11 and 12 are sectional views illustrating the formation of the half-nut by a secondary bending of the second preform using a second die, a third die, and a second punch in the half-nut manufacturing method according to the present invention. Best Mode for Carrying Out the Invention

[21] In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a method of manufacturing a half-nut made of a steel plate comprising: preparing the steep plate having a predetermined size; cutting the steel plate, to form a flat first preform including a first member preform; primarily bending the first member preform of the flat first preform, to form a second preform including a second member preform, the second member preform including a semicircular curved portion and a pair of inclined plane portions extending obliquely from distal ends of the semicircular curved portion, and simultaneously, coining an inner surface of the semicircular curved portion, to form a female screw at the inner surface of the semicircular curved portion, the female screw including a plurality of screw threads and screw valleys arranged alternately with each other; and secondarily bending the inclined plane portions of the second preform, to form a half-nut including a pair of flat plane portions extending parallel to each other from the distal ends of the semicircular curved portion. Mode for the Invention

[22] Now, a method of manufacturing a half -nut made of a steel plate according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[23] FIGS. 1 and 2 illustrate an example of a fixture, to which a half-nut according to the present invention is applied. The fixture 10 is manufactured by press-forming a steel plate such as a hot-rolled steel plate, a cold-rolled steel plate, a molten-zinc-plated steel plate, a stainless steel plate, etc. The steel plate may be replaced by other metal plates such as a copper or aluminum plate, etc., or alloy plates. A half-nut 30 is provided at a side of the fixture 10, to fasten the fixture 10 to a bolt 20. Although the bolt 20 shown in FIG. 1 is a foundation bolt partially embedded in a concrete structure 22, it is given only for an exemplary purpose, and the bolt 20 may be replaced by a stud bolt, stud pin, or support bar, or may be replaced by a boss, protrusion, etc. protruding from the concrete structure 22. [24] The half-nut 30 includes a U-shaped steel plate member 32 having opened upper and lower surfaces and a side surface to receive the bolt 20 in a partial region thereof. The steel plate member 32 consists of a semicircular curved portion 32a and a pair of flat plane portions 32b extending parallel to each other from both distal ends of the curved portion 32a. The flat plane portions 32b of the steel plate member 32 define a space 32c to receive the bolt 20 therein, and are perforated with a pair of holes 32d corresponding to each other. An inner surface of the curved portion 32a is formed with a female screw 34 to enable the fastening of the bolt 20. The female screw 34 includes a plurality of screw threads 34a and screw valleys 34b arranged alternately with each other.

[25] A clamp 12 is penetrated through the holes 32d of the U-shaped steel plate member

32, to allow the bolt 20 received in the space 32c to come into close contact and be fastened with the female screw 34. The clamp 12 is provided at one end thereof with a spring 14 to provide an elastic force required to restrict a rotation of the clamp 12. The clamp 12 may be replaced by a pin, bolt, or the like to push the bolt 20 toward the female screw 34 so as to fasten the bolt 20 with the female screw 34.

[26] As shown in FIGS. 3 and 4, a width W2 of the screw valleys 34b is larger than a width Wl of the screw threads 34a. Although FIG. 4 illustrates a rectangular screw in which the screw threads 34a and the screw valleys 34b have a rectangular cross section, it is given for an exemplary purpose, and the female screw 34 may be a triangular screw, trapezoidal screw, circular screw, etc. Also, although the half-nut 30 provided at the side of the fixture 10 is illustrated and described, the half-nut 30 may be used singly.

[27] Now, a method of manufacturing the half-nut made of a steel plate according to the present invention having the above described configuration will be described with reference to FIG. 5.

[28] Referring to FIG. 6, after a steel plate 40 having a predetermined size is prepared

(SlO), the steel plate 40 is cut to have a predetermined shape, so as to form a flat first preform 130 (S 12). The steel plate 40 is prepared by a well-known shearing machine, and the cutting of the steel plate 40 is performed by a well-known press. In the press cutting, female and male cutting molds are used. The first preform 130, obtained from the steel plate 40 by the press-cutting, has outlines of the fixture 10 and the U-shaped steel plate member 32. That is, the first preform 130 includes a first tool preform 110 having the outline of the fixture 10 and a first member preform 132 provided at a side of the first tool preform 110 and having the outline of the U-shaped steel plate member 32.

[29] Meanwhile, to punch a plurality of holes in the steel plate 40 during the press- cutting, the female and male cutting molds may have a function of punching. In this case, the female and male cutting molds are called a "female die" and a "male die". FIG. 6 illustrates a pair of holes 132d punched in the first member preform 132 of the first preform 130. The holes 132d become the holes 32d of the U-shaped steel plate member 32 shown in FIGS. 1 and 2. The press-cutting may be performed several times according to the outlines of the fixture 10 and the half-nut 30.

[30] Referring to FIGS. 7 to 10, the flat first preform 130 is subjected to a primary bending and coining, to form a second preform 230 having a female screw 234 (S 14). Here, the second preform 230 includes a second member preform 232, and in turn, the second member preform 232 includes a semicircular curved portion 232a and a pair of inclined plane portions 232b extending obliquely by a predetermined angle from the curved portion 232a. The female screw 234 is formed at an inner surface of the semicircular curved portion 232a, and includes a plurality of screw threads 234a and screw valleys 234b arranged alternately with each other.

[31] The primary press-bending and coining is performed by use of a set of a first die 50 and a first punch 60. The first die 50 has a semicircular protrusion 52 protruding upward from the center of an upper surface thereof, and a pair of inclined supporting surfaces 54 extending from opposite ends of the protrusion 52 by an inclination angle of about 45 degrees. The protrusion 52 has a plurality of screw thread blades 56 arranged throughout a surface thereof by a predetermined interval, to form the screw valleys 234b. A width W3 of the screw thread blades 56 is larger than a width W4 between the adjacent two screw thread blades 56. Accordingly, a width Wl of the screw threads 234a, obtained by the primary press-bending and coining, is smaller than a width W2 of the screw valleys 234b. The first punch 60 has a semicircular recess 62 defined at the center of a lower surface thereof to be engaged with the semicircular protrusion 52 of the first die 50, and a pair of inclined pressing surfaces 64 extending from opposite ends of the recess 62 by an inclination angle of about 45 degrees.

[32] As shown in FIGS. 7 and 8, to perform the primary bending and coining on the flat first preform 130, after the first member preform 132 is put on the protrusion 52 of the first die 50 by an operator, the first punch 60 is moved toward the first die 50, to press the first member preform 132. As shown in FIGS. 9 and 10, when the first member preform 132 is pressed by operation of the first punch 60, the protrusion 52 of the first die 50 is engaged with the recess 62 of the first punch 60, thereby forming the semicircular curved portion 232a of the second member preform 232.

[33] Then, the screw valleys 234b are formed as the screw thread blades 56 of the first die 50 are inserted into the inner surface of the curved portion 232a. The screw threads 234a are naturally formed at the inner surface of the curved portion 232a in regions defined by the width W4 between the screw thread blades 56. The inclined pressing surfaces 64 of the first punch 60 press the first member preform 132 on the inclined supporting surfaces 54 of the first die 50, to form the pair of inclined plane portions 232b extending obliquely from the distal ends of the curved portion 232a by an inclination angle of about 45 degrees. With the primary bending and coining of the first member preform 132, the screw threads 234a and the screw valleys 234b of the female screw 234 can be simply and precisely processed.

[34] Although FIGS. 7 and 9 illustrate and describe the inclined plane portions 232b having an inclination angle of about 45 degrees obtained by the primary bending, the bending angle of the inclined plane portions 232b may be appropriately changed if necessary. Meanwhile, although the primary bending and coining of the first preform 130 by the downward movement of the first punch 60 is described, the first punch 60 may be configured to be moved upward.

[35] As shown in FIGS. 8 and 10, since the width W3 of the screw thread blades 56 is larger than the width W4 between the adjacent two screw thread blades 56, the screw thread blades 56 have only the minimum wear and breakage during the bending and coining, and this has the effect of lengthening the life-span of the first punch 60. Specifically, to process the screw threads 34a having the same width Wl as one another and the screw valleys 34b having the same width W2 as one another, the screw thread blades 56 must have the same width as one another and the width between the adjacent screw thread blades 56 must be even. However, this may cause a narrow width W3 of the screw thread blades 56, resulting in the wear and breakage of the screw thread blades 56. After the first punch 60 is returned to an initial position thereof, the second preform 230 is separated from the first die 50 by the operator.

[36] Referring to FIGS. 11 and 12, the inclined plane portions 232b of the second preform 230 is subjected to secondary bending, to form the half-nut 30 having the pair of flat plane portions 32b (S 16). The secondary press-bending is performed by use of a set of a second die 70, a third die 80, and a second punch 90. The second die 70 has a center bore 72. The inclined plane portions 232b of the second preform 230 are put on and supported by an upper surface of the second die 70. The third die 80 is spaced apart upward from the second die 70 by a predetermined distance. The third die 80 has a center bore 82 to be aligned with the bore 72 of the second die 70. As shown in FIG. 12, a size of the bore 82 is determined such that the flat plane portions 32b of the completed half-nut 30 come into contact with an inner surface of the bore 82. The second punch 90 is mounted movably in the bore 72 of the second die 70. The second punch 90 has a semicircular protrusion 92 formed at an upper end thereof.

[37] To perform the secondary bending on the second preform 230 obtained by the primary bending and coining, the semicircular curved portion 232a is put on the protrusion 92 of the second punch 90 protruding from the bore 72 of the second die 70 by the operator, and the inclined plane portions 232b of the second preform 230 is supported by the upper surface of the second die 70. If the second punch 90 is operated to be lifted out of the bore 72 of the second die 70, the second member preform 232 of the second preform 230 is lifted together with the second punch 90, thereby being introduced into the bore 82 of the third die 80.

[38] Subsequently, by operation of the second punch 90, the inclined plane portions

232b of the second member preform 232 are bent to extend vertically as they come into contact with the inner surface of the bore 82, thereby forming the flat plane portions 32b of the half-nut 30. After the second punch 90 is returned, the half-nut 30 is separated from the second die 70 by the operator. If the half-nut 30 is completed as described above, the fixture preform 110 is subjected to press-forming, to complete the fixture 10. In an alternative embodiment, the second punch 90 may be moved downward from the second punch 80, to process the second member preform 232 into the U-shaped steel plate member 32.

[39] 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. Industrial Applicability

[40] As apparent from the above description, according to the present invention, a female screw can be simply and precisely formed at an inner surface of a U-shaped steel plate member by press-forming including bending and coining, etc. As a result, the present invention can achieve an improved productivity and reduced manufacturing costs of a half- nut and have far-reaching effects.

[41]

[42]

Claims

[1] A method of manufacturing a half- nut made of a steel plate comprising: preparing the steep plate having a predetermined size; cutting the steel plate, to form a flat first preform including a first member preform; primarily bending the first member preform of the flat first preform, to form a second preform including a second member preform, the second member preform including a semicircular curved portion and a pair of inclined plane portions extending obliquely from distal ends of the semicircular curved portion, and simultaneously, coining an inner surface of the semicircular curved portion, to form a female screw at the inner surface of the semicircular curved portion, the female screw including a plurality of screw threads and screw valleys arranged alternately with each other; and secondarily bending the inclined plane portions of the second preform, to form a half-nut including a pair of flat plane portions extending parallel to each other from the distal ends of the semicircular curved portion.

[2] The method according to claim 1, wherein a width of the screw valleys is larger than a width of the screw threads.