JPH11342448A - Method of machining connected end portion of deformed bar for concrete reinforcing and deformed bar machined by this method and connection structure of deformed bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make machining possible without destroying the reinforcing bar structure of the connected portion and improve mechanical strength of the connected portion by upsetting the connection end portion of a deformed bar at ordinary temperature, forming the maximum diameter as same as or a little larger than the bar-like body with a circular cross-section of the deformed bar or a little smaller than the diameter of the deformed bar, and rolling the threaded portion to conform to the upset diameter on the outer peripheral surface. SOLUTION: At least one connection end portion of the deformed bar is upset at ordinary temperature for forwarding the maximum diameter of the bar-like body with a circular cross-section of the deformed bar as sama as or a little larger than or a little smaller than the deformed bar. On the outer peripheral surface of the deformed bar connected portion after upsetting, the threaded portion to conform to the upset diameter is formed through the rolling/forming process. By this method, it is possible to maintain the fibrous structure particular to the deformed bar as a cutting work is not carried out, the structure is not varied as heating is not added and, furthermore is not weakened due to machining/hardening because the connection end portion is not swollen in diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of processing a connection end screw of a deformed steel bar for concrete reinforcement forming a framework of a construction at a construction or civil engineering site, and a connection of the deformed steel bar and the deformed steel bar processed by this method. Regarding the structure.

[0002]

2. Description of the Related Art In general, at construction and civil engineering sites, after a basic framework is formed using deformed steel bars for concrete reinforcement, a construction is set up in a process of placing and curing concrete. Here, the deformed steel bar has protrusions on the surface, protrusions in the axial direction are called “ribs”, and protrusions other than the axis are called “nodes”.

[0003] Since the deformed steel bars for concrete reinforcement are supplied to the manufacturer after being cut into predetermined lengths, the deformed steel bars for concrete reinforcement are cut or interconnected depending on the size of the work. It is designed to be cut into lengths for use.

[0004] When interconnecting, a latching method is used in which the connecting ends of the deformed steel bars are overlapped and then bound with an iron wire.

However, since the connecting ends of the deformed steel bars are used in a superposed manner, the loss of material is large. Since the deformed steel bars are connected by using an iron wire, the connecting portion weakens over time. There was a problem that the labor cost associated with the connection work was large.

Further, since the reinforcing steel connected by the latching method is cast with concrete mortar, and after curing is completed, the characteristics of the connected reinforcing steel structure are exhibited only by the adhesive force with the concrete. If a mortar or curing problem occurs, the fragile structural properties of the structure may appear.

As a method for solving such a problem, there has been proposed a method of hot expansion of a connection end, which is a kind of mechanical connection method. After heating the connection end,
In this method, a force is applied in the axial direction of the deformed steel bar to expand the connection end.

[0008] However, in this method, there is also a case where the material is lost due to the reduction in the length of the deformed bar.

Further, since heat is locally applied to the connection end, the elongation rate is reduced due to a change in the material structure of the connection end member between the portion affected by the heat and the portion not affected by the heat, and the connection end is weakened by impact. However, there is a problem that irregular tissue distribution appears due to partial heating.

In order to solve this problem, a cold method has been developed as a different method. That is, in this method, the connecting end is expanded at a normal temperature along the axial direction of the deformed steel bar with a large pressure (FIG. 12).
In the method, a first thread forming a cutting thread at a connection end is provided.
A method and a second method of forming a rolled thread after skimming the expanded connection end (SKIM) have been presented.

Incidentally, the first method was developed by Techniple S.A. of France and disclosed in Korean Patent Publication No. 94-8311 and corresponding US Pat. No. 5,158,527. However, the second method was developed by CCL in the United Kingdom and is disclosed in United Kingdom Patent No. 2 286 782 A.

However, the UPSETTING METHO method
The deformed steel bars processed according to D) have the problem that the tensile strength and hardness become extremely high due to work hardening, and the impact absorption energy value drops sharply.

On the other hand, when comparing the metallographic structure of the expanded end portion of the deformed steel bar (FIGS. 13 and 14) with the metallographic structure of the original material (FIGS. 15 and 16), FIG. 13 and FIG. FIG. 15 shows the metal structure along the axial direction of the original material. In FIG. 15, the ferrite and pearlite structures are long and continuously advanced in the axial direction, while in FIG. It can be seen that the continuity is interrupted.

FIGS. 14 and 16 show the swollen diameter and the structure of the original material along the direction perpendicular to the axis, respectively. In the original material of FIG. 16, the ferrite and pearlite structures are uniformly distributed. On the other hand, it can be seen that the metal structure is considerably coarsened in the enlarged diameter portion in FIG. Thus, it can be seen that the texture of the swollen portion is formed unevenly.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of threading a connecting end of a deformed steel bar for concrete reinforcement and a connecting structure of the deformed steel bar processed according to this method in order to solve the above-mentioned problems. To provide.

Another object of the present invention is to provide a method of processing a connection end portion of a deformed steel bar for concrete reinforcement which can maintain a structure on a fiber inherent to the deformed steel bar by not performing a cutting process. An object of the present invention is to provide a connection structure of deformed steel bars obtained by using this method.

Another object of the present invention is to provide a method for processing a connecting end of a deformed steel bar for concrete reinforcement which does not change its structure by applying no heat, and a connection structure for a deformed steel bar obtained by using this method. To provide.

Another object of the present invention is to provide a method of processing a connection end portion of a deformed steel bar for reinforcing concrete to compensate for a weakened structure due to work hardening by preventing the connection end portion from expanding. The present invention provides a connection structure for deformed steel bars.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, a concrete reinforcing deformed steel bar is provided with at least one connecting end of the concrete reinforcing deformed steel bar having ribs and a number of nodes. The maximum diameter of the connecting end is the same as, slightly larger than, or slightly smaller than the diameter of the deformed bar depending on the degree of processing. And a method of processing a connection end of a deformed steel bar for concrete reinforcement in which a thread portion having a diameter corresponding to the upset diameter is formed in the outer peripheral surface of the connection end of the deformed steel bar after the upsetting process by a roll forming process. I do.

Further, the present invention provides a concrete reinforcing method in which at least one connection end is set at room temperature and a threaded thread is formed on the outer peripheral surface of one connection end of the deformed steel bar which has been subjected to the setting step. Characterized by deformed steel bars.

Further, the present invention relates to a deformed steel bar in which at least one connecting end is set at room temperature and a rolled screw portion is formed on the outer peripheral surface after the upsetting step, corresponding to the rolled screw. It is characterized by a connection structure of a deformed steel bar for concrete reinforcement, which is connected by a connector having a screw of the form.

[0022]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a deformed steel bar for concrete reinforcement before processing. The deformed steel bar for concrete reinforcement (100) is shown in FIG.
Is composed of a rod-shaped body (10) having a circular cross section, ribs (30) and nodes (20) formed at equal intervals on the outer peripheral surface thereof.

The long deformed steel bar is generally used in FIG.
In some cases, the connecting end (40) is bent (or bent) with respect to the intermediate portion of the deformed steel bar as shown in FIG.

FIG. 2 shows the upsetting process, and the upsetting die (9) composed of two or more pieces or rollers (FIG. 17 is a front view, and FIG. 18 is a side view). After the fluid is inserted into the container, a fluid or mechanical force is applied to perform the upsetting at room temperature.

Also, the rib at the connecting end (40) shown in FIG.
Crimping is performed so that the diameters of (30) and the node (20) are substantially the same as the diameter (11) of the circular rod having a circular cross section of the deformed steel bar (100).

Thus, the shaft (19) of the rod-shaped body (10) having a circular cross section is
The shaft (59) of the upset portion (50) is concentric.
Further, by performing this step, the deformed protruding portion of the rib (30) and the deformed steel bar can be straightened.

Thereafter, as in FIG. 3, the section of the protruding end portion (40) protruded by the upsetting process is shaved, and the section (53) is flattened by front cutting and chamfering (Facing & Chamfering). The chamfering operation is performed on the outer edge (55) of ().

FIG. 5 is a state diagram showing a state of the deformed steel bar which has been processed.

Thus, the fastening force of the deformed steel bar is improved by suppressing damage to the screw at the corner when handling the deformed steel bar.

Further, a threaded portion (60) is formed on the outer peripheral surface of the upset portion (50) by rolling in the same manner as in FIG.

The outer diameter (61) of the rolled screw portion (60) is formed to be the same as or slightly larger than the diameter (11) of the rod-shaped body (10) having a circular cross section.

By doing so, the metal structure of the thread part material according to the present invention is not cut, and the mechanical strength of the plastically processed screw part is improved, and the metal structure becomes denser, and at the same time, the inside of the connection part has a unique structure. , It can withstand large loads and impacts.

FIGS. 9 and 10 show photographs of the structure of the connection end portion of the deformed steel bar according to the present invention. FIG. 9 shows the metal structure of the deformed steel bar along the axial direction, and FIG. The continuity of the pearlite and ferrite structures shown is more clearly apparent, indicating that the structure is also denser.

FIG. 10 shows the metal structure of the deformed steel bar along the direction perpendicular to the axis, which appears denser than the pearlite and ferrite structures shown in FIG.

However, in the processing of the thread portion, various screws such as a circular screw or a triangular screw can be processed, but more preferably, the processing is performed with a circular screw.

For example, a screw can be machined as shown in FIGS.

The reason for this is that when processing with a circular screw, the cross section of the thread is rounded and the root portion is made thick like a trapezoidal screw, so that the resistance is increased, and as a result, the notch phenomenon occurs. Of course, this does not occur because the fastening force is increased and the fastening can be easily performed on a construction site where there is much dust and sand.

When the pitch of the circular screw is smaller than that of a general screw, not only the fastening force and strength are improved, but also there is no possibility of loosening even if a large vibration is generated.

Further, the rib (3) is formed from the roll-formed screw portion (60).
0) and the thread groove diameter (63) at the border (65) adjacent to the node (20)
Can be gradually increased as shown in FIG. 6 to suppress the stress concentration phenomenon.

Although FIG. 1 shows a deformed steel bar (100) for reinforcing concrete on which ribs (30) and nodes (20) are formed, the present invention is not limited to this, and the present invention is not limited thereto. It is also applicable to deformed steel bars for concrete reinforcement having ribs formed by X-rays.

The method of connecting the deformed steel bars for concrete reinforcement formed as described above is shown in FIG.
A nut portion corresponding to the shape of the roll-formed screw portion (60) for connecting the roll-formed screw portion (60) formed at the connection end portion (40) of each deformed steel bar (100) (FIG. 11B, A coupler (200) provided with FIG. 11C) was employed.

[0043]

As described above, according to the present invention, it is possible to increase the mechanical strength of the joint of a deformed steel bar for concrete reinforcement used in construction and civil engineering sites without destroying the reinforcing steel structure of the joint. it can.

Since the connecting portion can be formed by the upsetting die and the rolling process, the process is extremely easy, and the production cost can be reduced accordingly. Especially when processing with circular screws, the connection is very easy and the connection work is very easy, shortening the construction period and reducing the cost, compared with the connection structure of deformed steel bars manufactured by the conventional expanding method. Another advantage is that the length of the deformed steel bar is maintained, so that about 1-2% of the material can be saved.

[Brief description of the drawings]

FIG. 1 is a view showing a deformed steel bar for concrete reinforcement before being processed by the processing method of the present invention.

FIG. 2 is an explanatory view showing one stage in processing a connection end of a deformed steel bar for concrete reinforcement according to the present invention.

FIG. 3 is an explanatory view showing another stage in processing the connection end.

FIG. 4 is an explanatory view showing still another stage in the processing of the connection end.

FIG. 5 is an explanatory view showing a state of the deformed steel bar after the operation according to the processing method of the present invention is completed.

FIG. 6 is an enlarged view of a screw portion of FIG. 5;

FIG. 7 is a view showing a preferred embodiment of the screw portion.

FIG. 8 is a view showing another preferred embodiment of the screw portion.

FIG. 9 is a metallographic view of the connecting end portion of the present invention along the axial direction.

FIG. 10 is a metallographic view of the connecting end portion of the present invention along the direction perpendicular to the axis.

FIG. 11 is a view showing a state where the deformed steel bars of the present invention are connected by a coupler.

FIG. 12 is a view showing a state in which a connection end of a deformed steel bar for concrete reinforcement according to the related art is expanded (UPSETTING).

FIG. 13 is a metallographic view of the connection end portion of FIG. 12 along the axial direction.

FIG. 14 is a metallographic view of the connection end portion of FIG. 12 along the direction perpendicular to the axis.

FIG. 15 is a metallographic view of an original material used in the present invention and the prior art, along the axial direction.

FIG. 16 is a metallographic diagram of an original material used in the present invention and the conventional technique, taken along a direction perpendicular to the axis.

FIG. 17 is a front view of a mold showing a state in which a connection end of a deformed steel bar for reinforcing concrete is set up.

FIG. 18 is a side view of the mold shown in FIG.

[Brief description of reference numerals]

9: Mold 10: Cross-section circular rod 11: Diameter of cross-section circular rod 19: Shaft of cross-section circular rod 20 and 4 ... Section 30 and 6 ... Rib 40 ... Connection end 50 ... Upset 53 … Cross section of connection end 55… Cross edge of connection end section 59… Shaft of upset part 60… Screw part 61… Screw part outer diameter 63… Screw groove diameter 65… Boundary 100… Deformed steel bar for concrete reinforcement 200… coupler

Claims (8)

[Claims] 1. A cross-section circular bar of a deformed steel bar for concrete reinforcement, wherein at least one connection end of the deformed steel bar for concrete reinforcement having ribs and a number of nodes is inserted at room temperature and the connection is made. The maximum diameter of the end is the same as the diameter of the cross-section circular rod of the deformed steel bar,
An upsetting step of forming a slightly larger or slightly smaller diameter than the deformed bar depending on the degree of processing; and forming a threaded portion corresponding to the upset diameter on the outer peripheral surface of at least one connection end of the deformed bar that has undergone the upsetting step. A method of processing a connection end of a deformed steel bar for concrete reinforcement, which is performed in a forming process. 2. A shaft of a connecting end portion of the deformed steel bar that has undergone the upsetting step and a shaft of a cross-sectionally circular rod-shaped body of the deformed steel bar formed with the ribs and the nodes are arranged concentrically. 2. A method for processing a connection end of a deformed steel bar for concrete reinforcement according to 1. 3. The connecting end of a deformed steel bar for concrete reinforcement according to claim 1, wherein a cutting step of cutting and chamfering a side end face of a connecting end portion of the deformed steel bar after the upsetting step is added. How to process the part. 4. The concrete reinforcing method according to claim 1, wherein in the rolling forming step, a groove diameter of a thread at a boundary adjacent to the rib and the node in the threaded portion of the rolling forming is gradually increased. Of connecting end of deformed steel bar. 5. A cross-sectional circular bar of a deformed steel bar for concrete reinforcement, wherein at least one connection end of the deformed steel bar for concrete reinforcement having ribs and a number of nodes is set at room temperature. A deformed steel bar for reinforcing concrete, wherein a threaded thread is formed at one connecting end of the deformed steel bar that has undergone the upsetting process. 6. The deformed steel bar for reinforcing concrete according to claim 5, wherein a maximum diameter of the raised connection end is substantially the same as a diameter of the rod having a circular cross section. 7. The deformed steel bar for reinforcing concrete according to claim 5, wherein an outer diameter of the roll-formed screw portion is formed to be the same as or slightly larger than a diameter of the cross-sectionally circular rod-shaped body of the deformed steel bar. 8. The deformed steel bar for reinforcing concrete according to claim 5, wherein a groove diameter of a thread at a boundary adjacent to the rib and the node in the roll-formed screw portion is gradually increased.