JP2860472B2 - Anchor bolt and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anchor bolt buried in basic concrete for fixing steel columns for civil engineering construction, installing mechanical equipment, and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as an anchor bolt, a rib protruding in the axial direction of a steel bar serving as a base body and a flange protruding in a circumferential direction at a constant interval over the entire length in order to increase the adhesion to concrete. It can be seen that a surface protruding portion such as is formed and a screw portion is formed at the tip thereof.

In order to form a bolt at the tip of the anchor bolt, the surface projection at the tip is removed by cutting, and the surface is formed into a cylindrical shape, and then threaded by cutting. As a result, the crystal structure aligned in the axial direction obtained at the time of molding the material is interrupted, the strength of the bolt forming part is lower than that of the non-processed part, and to obtain the required strength, it has a diameter one size larger than that If it is not an anchor bolt, it is useless and has disadvantages such as high cost.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an anchor bolt capable of improving the strength of a bolt forming portion as compared with a non-processed portion and a method of manufacturing the same.

[0005]

In view of the problem that the strength of the bolt forming portion is lower than that of the non-processed portion based on the above-mentioned prior art, the present invention provides only the surface protrusion of the anchor bolt end by cold plastic working. After deforming so as to be substantially flat and forming such a processed end into a substantially cylindrical shape having substantially the same diameter as the base portion of the anchor bolt, the plastic end is formed on the processed end by cold plastic working by thread rolling. By forming screws, deformation of surface protrusions due to plastic deformation in the cold and formation of male threads, work hardening to improve the strength of the machined end, which is the bolt forming part, compared to the non-machined part. Thus, the above-mentioned disadvantage has been solved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.
An anchor bolt buried in foundation concrete for installation of ancillary equipment and mechanical equipment, etc. The anchor bolt 1 is provided on the surface of a steel bar as a base section 2 having a circular cross section as shown in FIG. A rib, which protrudes in the axial direction, and a surface protruding portion 3, 3a, such as a bush, which protrudes in the circumferential direction at regular intervals over the entire length, is formed at the tip of the anchor bolt 1 protruding from the foundation concrete. Form a bolt portion 4.

The buried base end of the anchor bolt 1 is not limited to a straight shape as shown in FIG. 1, but may be a U-shaped hook formed by bending the buried base end or an anchor beam (not shown). Alternatively, in order to fix the anchor plate, a bolt portion similar to the above may be formed at the buried base end portion.

The anchor bolt 1 shown in FIG. 1A shows a non-machined state. At the end Y of the anchor bolt 1 (where the bolt portion 4 is formed), surface projections 3, 3a. ) Is formed by cold plastic working to form the bolt portion 4.

As shown in FIG. 1 (b), only the surface projections 3, 3a at the ends of the anchor bolt 1 are substantially flattened by the cold plastic working (see FIG. 1 (b)). 3a), the processed end portion 5 is formed into a substantially cylindrical shape having a diameter D1 substantially equal to the diameter D of the base portion 2 by deforming as shown in FIG. 1 (c). As shown in the figure, a male screw 6 whose average diameter D2 is almost the same as the diameter D of the base 2 and the diameter D1 of the processed end 5 is formed at the processed end 5 by cold plastic working by thread rolling. doing.

[0010] The shape and arrangement of the brush are shown in FIGS.
In the case of a so-called horizontal brush as shown in the figure, it is preferable that the brushes on both sides which are divided into semicircles by a rib (up and down in the figure) are not arranged on the same circumference but are staggered at a predetermined interval. Since the uniform strength can be obtained as compared with those arranged on the same circumference, the former is better. However, the present invention is not limited to such a method.
When the plastic deformation of 3a... Is performed, it may be a continuous brush that can uniformly work harden the entire area of the bolt portion 4.

Next, a method of manufacturing the anchor bolt 1 will be described. In addition, although the figure shows the anchor bolt 1 provided with the bolt part 4 at the tip, the anchor bolt 1
Even when the bolt portion 4 is provided at both the distal end portion and the buried proximal end portion, it is manufactured in a similar manufacturing process.

First, as shown by a dashed line in FIGS. 1A and 2, in the anchor bolt 1 in a non-processed state, the surface projection 3 at the tip end Y where the bolt portion 4 is formed,
Only 3a ... (indicated by X in the figure) is subjected to cold plastic working such as drawing, rolling, or cold pressing, that is, plastic working at a temperature lower than the recrystallization temperature, as shown in FIG. As shown by the solid line at the left end in FIG. 2, while maintaining the diameter D of the base portion 2, it is plastically deformed, crushed and compressed so as to be substantially flat, and the base portion 2 of the anchor bolt 1 is formed. It has a substantially cylindrical shape with a smooth surface and a diameter D1 substantially the same as the diameter D.

In FIG. 1 (b), the portion indicated by the two-dot chain line corresponds to FIG.
The surface projections 3, 3a... shown in (a) are crushed by the above-mentioned cold plastic working and are almost flattened. The cold plastic working of the crushed surface projections 3, 3a. Substantially, the material is moved locally because the tip end portion Y of the anchor bolt 1 is locally worked, as shown in FIG. 1B, in the longitudinal direction of the anchor bolt 1 as compared with the unprocessed state shown in FIG. It becomes slightly longer to be absorbed, and the plastic deformation of the surface projections 3, 3a... Causes work hardening to increase static strength, impact strength and fatigue strength.

Next, plastic deformation is applied only to the surface layer of the processing end portion 5 by cold plastic working such as rolling, as shown by the two-dot chain line in FIGS. 1 (c), 3 and 2. , Average diameter
D2 forms a male screw 6 which is almost the same as the diameter D of the base 2 and the diameter D1 of the machined end 5.

[0015] In plastic deformation by cold plastic working such as rolling, in the case of thread cutting by cutting, the crystal structure aligned in the axial direction obtained at the time of forming the material is interrupted. Since the shape of the male screw 6 is formed by the swelling of the material, a continuous fibrous structure can be obtained, and work hardening increases static strength, impact strength, and fatigue strength.

The continuity of the crystal structure by the plastic deformation is maintained in the crushing step of the first step.
Through the crushing step of the step and the screw forming step of the second step, the strength of the bolt portion 4 is set to be equal to or higher than the base material strength of the non-processed portion other than the bolt portion 4 or the non-processed anchor bolt 1.

The anchor bolts 1 shown in FIGS. 1 and 2 show the surface projections 3, 3a... In a simplified manner in the drawings, and are shown by two-dot chain lines in FIG. 1 (b). The non-molded portion A of the flattened brush is slightly larger than the flattened brush width B, that is, the flattened brush width B on the same circumference.
Although it is seen that it is not the same as or more than the part without the bulge (non-molded part A of the bulge), the actual base material of the anchor bolt 1 has a bulge width B of the bulge width as shown in the detailed view of FIG. Because it is wider than the molded part A, the semicircular part always has a width B which is work hardened wider than the non-molded part A on the same circumference, so it is interrupted in the radial direction on the same circumference. To compensate for the strength of the part.

[0018]

Next, examples of the present invention are as follows.
Base material types SD295A and SD345, D25
The first step was performed by drawing using an anchor bolt (horizontal brush), and the second step was performed by thread rolling. As a result, the tensile strength of the bolt portion was improved by about 10% with respect to the base material strength in any of the anchor bolts.

[0019]

In summary, the present invention is directed to an anchor bolt 1 having a surface projection such as a bush and a rib on the surface, and only the surface projections 3, 3a at the end of the anchor bolt 1 are formed by cold plastic working. After being deformed so as to be substantially flattened and forming the processed end 5 into a substantially cylindrical shape having substantially the same diameter as the base 2 of the anchor bolt 1, the processed end is formed by cold plastic working by thread rolling. Since the male screw 6 is formed in the portion 5, the processed end portion 5 is work hardened by the crushing of the surface protrusions 3, 3a... Since there is no need to use an anchor bolt having a diameter one size larger than in the related art, the cost can be reduced.

A method of manufacturing an anchor bolt 1 having a surface projection such as a brush and a rib on its surface, wherein only the surface projections 3, 3a at the end of the anchor bolt 1 is substantially flattened by cold plastic working. The processed end 5
And forming a male screw 6 on the processing end 5 by cold plastic working by thread rolling. Since the strength of the end portion 5 is set to be equal to or greater than the base material strength, only the surface protrusions 3, 3a... .. Or the surface portion of the base 2 only requires a small amount of processing power, simplifies equipment and reduces processing costs, and furthermore, the surface projections 3, 3a
The surface of the anchor bolt 1 is work-hardened by the plastic deformation of..., And the strength of the processed end portion 5 can be improved to the base material strength or more.

Further, since the male screw 6 is formed by cold plastic working, the metal flow (continuous) formed in the axial direction obtained at the time of forming the material, as in the case of forming the male screw by cutting, is used. Uninterrupted crystal structure), a continuous fibrous structure can be obtained, and work hardening improves static strength, impact strength and fatigue strength, and the strength of the processed end 5 can be improved. Its practical effects are enormous.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing an anchor bolt according to the present invention.

FIG. 2 is a front view showing a process of machining a bolt portion of the anchor bolt.

FIG. 3 is an enlarged end view of FIG. 1 (c).

FIG. 4 is a front view showing a detailed form of a base material of the anchor bolt.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anchor bolt 2 Base part 3, 3a ... Surface projection 5 Processing end 6 Male thread

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B21K 1/00-31/00 B21H 1/00-9/02 B21J 1/00-13/14 B21J 17/00-19 / 04 E02D 27/00

Claims (2)

(57) [Claims] 1. An anchor bolt having a surface projection such as a brush and a rib on its surface, wherein only the surface projection at the end of the anchor bolt is deformed by cold plastic working so as to be substantially flattened. An anchor bolt having a machined end formed in a substantially cylindrical shape having substantially the same diameter as the base portion of the anchor bolt, and then forming an external thread on the machined end by cold plastic working by thread rolling. . 2. A method of manufacturing an anchor bolt having a surface projection such as a brush and a rib on a surface, wherein only a surface projection at an end of the anchor bolt is deformed to be substantially flat by cold plastic working. Forming a working end portion into a substantially cylindrical shape having substantially the same diameter as the base portion of the anchor bolt, and forming a male screw at the working end portion by cold plastic working by thread rolling. A method of manufacturing an anchor bolt, wherein the strength of a processed end portion is equal to or higher than the base material strength.