WO2001023118A1

WO2001023118A1 - Method of processing connecting ends of deformed steel bar used for reinforcing concrete, and deformed steel bar processed by this method

Info

Publication number: WO2001023118A1
Application number: PCT/KR1999/000581
Authority: WO
Inventors: Gyeng-Ok Chung; Chung-Ki Yoo
Original assignee: Chung Gyeng Ok; Yoo Chung Ki
Priority date: 1999-09-27
Filing date: 1999-09-27
Publication date: 2001-04-05
Also published as: AU6008099A; JP3780209B2

Abstract

A method of processing the connecting ends of deformed steel bars used for reinforcing concrete, comprising the steps of either machining a raw material for a deformed steel bar and forming rolled threads in the ribs and nodes or swaging the connecting end of the deformed steel bar to provide a greater diameter than that of a barrel and forming rolled threads therein, thereby improving the mechanical strength and faciliting processing while retaining the intrinsic fiber structure of deformed steel bars and the processing cost is greatly reduced; and a deformed steel bar obtained by this method. While cold swaging is performed such that a predetermined region on the side associated with the connecting end of at least one deformed steel bar having transverse ribs and a number of circumferential nodes on its cylindrical barrel surface is plastically deformed at ordinary temperature, the method includes a first stage for processing the transverse ribs and circumferential nodes to have a diameter greater than that of the cylindrical barrel by a predetermined amount, and a second stage for forming a threaded portion by rolling a predetermined region on the side associated with the connecting end of the swaged, deformed steel bar.

Description

Description Processing method of connecting end of deformed steel bar for concrete reinforcement and

TECHNICAL FIELD The present invention relates to a method of threading a connection end of a deformed steel bar for concrete reinforcement which forms a framework of a construction at a construction or civil engineering site, and a deformed steel bar processed by this method. It is about. BACKGROUND ART In general, at construction and civil engineering sites, concrete structures are erected in the process of casting and curing concrete after setting up a basic framework using deformed steel bars for concrete reinforcement. Here, atypical ^ means that protrusions are formed on the surface, but usually, the protrusions in the axial direction are called “reaves”, and the protrusions other than the axis, that is, the protrusions in the circumferential direction are “nodes”. Called.

Since the above-mentioned deformed steel bars for concrete reinforcement are cut and supplied at a specified length by the manufacturing industry, it is necessary to cut or interconnect the deformed steel bars for concrete reinforcement depending on the size of the construction. Will be used at a reasonable length.

Conventionally, when interconnecting the above-mentioned deformed steel bars, a latching method in which the connecting ends of the respective deformed steel bars are overlapped and then bound with an iron wire has been used. However, this is a problem in that the connection end of each deformed steel bar is used in an overlapping manner, resulting in a large loss of material, and since the deformed steel bars are connected using iron wire, the connection part becomes weaker with the passage of time. At the same time, there was a problem that the loss of manpower accompanying the connection work increased and the cost increased.

Reinforcing bars connected by the latching method are driven by concrete mortar, and after curing is completed, steel bars connected for the first time by the adhesive force with concrete Due to the strength of the muscle structure, if there is a problem with concrete mortar or curing, the fragile structural properties of the structure can appear.

As a method for solving such a problem, a hot upsetting method of a connection end, which is a kind of mechanical connection method, has been proposed. In this method, after the connection end was heated, a force was applied in the axial direction of the deformed steel bar, the connection end was set up, and a rolling screw was machined at the upset portion.

However, this method also has a problem that the material is lost due to the reduced length of the deformed bar. In addition, since hot working is performed by locally applying heat to the connection end, the elongation is reduced due to the structural change in the material of the connection end between the heat-affected part and the unaffected part, resulting in impact. There was a problem in that it was weak and showed irregular tissue distribution due to partial heating.

A different cold method has been developed to solve the above problems. In other words, as shown in FIGS. 1A and 1B, a method has been proposed in which the connection end of the deformed steel bar is upset at room temperature with a large pressure along the axial direction.

This is a first method of forming a cutting thread at the upset connection end, and a second method of forming a rolled thread after the upset connection end is subjected to a cutting (SCHIM) scheme. is there. For reference, the first method, which was developed by French Techables, is disclosed in Korean Patent Publication No. 94-8311 and its corresponding US Patent No. 5,158,527, and the second method Was developed in the UK CCL and is disclosed in UK Patent 2 286 782A.

However, the deformed steel bars processed by the above upset method have the problem that tensile strength and hardness are very high due to work hardening, and the impact absorption energy value drops sharply. It may also indicate the phenomenon of breaking at the processed part.

In order to improve the problem of the method of processing the connection end portion of the deformed bar by the cold upset method, in S Patent Publication No. 10-37386, as shown in FIGS. The cold plastic working by swaging is performed so that the diameter of the node (102) and the leave (103) of the predetermined section (dl) at the end side are the same as the diameter of the cylindrical body surface (101). The structure that formed the rolling screw (104) in the processed part Presented.

However, in the case of Japanese Patent Application Laid-Open No. Hei 10-37386, cold plastic working by swaging is used according to the purpose of work hardening, so that the plastic process is difficult, resulting in increased productivity. In addition, there is a problem that economic efficiency is reduced. Also, as shown in FIG. 2B, the process of performing swaging so that the diameter of the circumferential node (103) and the lateral leave (102) matches the diameter of the cylindrical body surface (101). Since the boundary between the sleeve and the cylindrical body has a different structure from each other, the notch is generated at the boundary between the leave and the cylindrical body surface as shown in the detailed diagram "Β '", and the tensile strength is increased. 2D, the deformed steel bars with connecting ends as shown in Fig. 2D are connected by a force blur and a tensile load is applied in the axial direction and the vertical direction of the shaft. In the case of hot-rolled products, pearlite and ferrite microstructures are arranged long in the working direction, but work hardening occurs when this part is subjected to primary cold plastic working. Occurs during secondary rolling screw machining. Curing atypical steel bar inside the organization there is a problem that is thus destroyed the work hardening occurs.

On the other hand, when comparing the metallographic structure of the upset connection end of the deformed bar (Figs. 6 and 6) with the metallographic structure of the original material (Figs. 7 and 7), Figs. 6 and 7 show the upset and the original material, respectively. Fig. 7 及び shows that the ferrite and pearlite microstructures are continuously elongated in the axial direction, while Fig. 6Α shows that the metal microstructures are discontinued in the axial direction. I understand.

On the other hand, Fig. 6 and Fig. 7 show the structure along the direction perpendicular to the axis of the upset and the base material, respectively.The ferrite and pearlite structures are uniformly distributed in the base material in Fig. 7 On the other hand, it can be seen that in the upset part in Fig. 6Β, the metal structure becomes considerably coarse. This shows that the texture of the upset portion is formed unevenly. Technical Problems Therefore, the present invention has been devised to solve the above various problems. Rolling thread processing into the lead and joint of the deformed steel bar without cutting, or swaging the connecting end of the deformed steel bar larger than the diameter of the fuselage surface. The method of processing the connection end of the deformed steel bar for concrete reinforcement, which has increased tensile strength while maintaining the inherent fiber structure of the deformed steel bar by forming the part, and the deformed steel bar connection end obtained by this method Providing a department has its purpose.

In addition, the present invention improves the mechanical strength by being manufactured by cold swaging and rolled screw processing without applying heat, thereby increasing the metal structure and reducing the internal structure including the cylindrical body. A method for adding a connection end of a deformed steel bar for concrete reinforcement, which is capable of withstanding high loads and impacts by being maintained in an inherent structure, and a connection end of a deformed steel bar obtained by this method There are other objectives in providing the department.

Further, the present invention provides a method of adding a connecting end of a deformed steel bar for concrete reinforcement to supplement a weak point of a structure due to work hardening by not upsetting the connecting end, and a deformed shape obtained by this method. Providing the connecting end of the steel bar has another purpose. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a schematic view of a connection end of a deformed steel bar processed by an upset method according to a conventional technique.

FIG. 1B is a diagram showing a shape obtained by rolling and forming a connecting end portion of a deformed steel bar processed by the upset method of FIG. 1A.

FIG. 2A to FIG. 2C are processing sequence diagrams of a connection end portion of a deformed steel bar according to the related art. FIG. 2D is a diagram of a paddle state of a notch portion generated by a cold plastic working degree.

3A to 3D are flowcharts showing a method of processing a connection end of a deformed steel bar for concrete reinforcement according to the present invention.

FIG. 3E is a thread shape diagram of the connection end portion of the deformed steel bar illustrated in FIG. 3D with the lateral joints facing upward. FIG. 4A and FIG. 4B are swaging state diagrams of the deformed bar according to the present invention. FIG. 5A and FIG. 5B are sequence diagrams for processing a rolled screw portion without performing a swaging step as another embodiment of the present invention.

FIG. 6A is a metallographic diagram along the axial direction of the connection end portion in FIG.

FIG. 6B is a metal thread diagram along a direction perpendicular to the axis of the connection end of FIG.

FIG. 7A is a metallographic diagram of an original material used in the present invention and the prior art along the axial direction.

FIG. 7B is a metallographic diagram along the direction perpendicular to the axis of the original material used in the present invention and the prior art.

FIG. 8A is a metallographic diagram of the connection end portion of the deformed steel bar according to the present invention in the axial direction.

FIG. 8B is a metal assembly diagram along a direction perpendicular to the axis of the connection end of the modified steel bar according to the present invention.

FIGS. 9A and 9B are desirable illustrations of threads formed at the connection end of the modified steel bar according to the present invention.

FIG. 10 is an enlarged view of the screw portion of FIG. 3E.

FIG. 11A to FIG. 11C are views showing a state in which a deformed steel bar for concrete reinforcement is connected with a coupler. BEST MODE FOR CARRYING OUT THE INVENTION In order to achieve the above object, the present invention relates to a method for connecting at least one of a transverse rib formed on a cylindrical body surface and a deformed steel bar having a number of circumferential nodes. Provided is a method for processing a connection end of a deformed steel bar for concrete reinforcement, in which a screw is processed only in a leave and a node formed in a predetermined section on an end side.

The present invention also relates to a deformed steel bar for interconnecting a deformed steel bar in which a lateral leave and a large number of circumferential nodes are formed on the surface of a cylindrical body, at least one end of the deformed steel bar. Although the predetermined section of the portion is formed by swaging to be larger than the diameter of the cylindrical body surface by a predetermined size, the swaging is performed as described above. The present invention provides a deformed steel bar for reinforcing concrete in which a thread is formed at a lateral leave and a circumferential node.

Further, in a deformed steel bar for interconnecting a deformed steel bar in which a lateral leave and a large number of circumferential nodes are formed on a cylindrical body surface, at least one of the above-described deformed steel bars has a predetermined section at one end. Is formed to be larger than the diameter of the cylindrical body surface by a predetermined size by swaging, but the above-mentioned swaged transverse ribs and threaded joints at the circumferential section are used for concrete reinforcement. Provide deformed steel bars.

(Example)

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Fig. 3A shows the deformed steel bar for concrete reinforcement before processing. The deformed steel bar for concrete reinforcement (100) has a prototype body (10) and nodes formed at equal intervals on the circumferential surface of the body. (20), and a lateral leave formed in the axial direction of the cylindrical body αο).

(30). Normally, when a long deformed steel bar is cut, the connecting end (40) may bend with respect to the middle part of the deformed steel bar as shown in Fig. 3Α. Figure 3Β shows the swaging process, in which a fluid or mechanical device is inserted into a swaging mold made of two or more pieces or rolls (Figure 4Α is a front view, and Figure 4Β is a side view). Perform the swaging process at room temperature with strong force. Along with this, the diameter of the leave (30) and the joint (20) of the connection end (40) shown in Fig. 3Α is squeezed by a predetermined size larger than the body diameter (10) of the deformed steel bar (100). The height (Η2) of the circumferential knot (20) and the horizontal leave (30) after being removed is the circumferential knot (Η) or the horizontal leave height (HI) of the original material. It is desirable to form 5 to 95% or more of this. This is because when the swaging diameter is less than 5% of the knot or leave height of the original material, that is, when it is close to the diameter of the cylindrical body, the notch probability increases, and when it is more than 95%, When approaching the knots or leave heights of the original material, the rolled thread machining length must be longer than the thread length corresponding to the nominal diameter of the deformed bar.

In this embodiment, the swaging diameter is equal to that of the knot or lead in the state of the original material. It is a well-known fact that the height is not necessarily limited to 5 to 95% of the bush height, but may appear slightly different depending on the manufacturing specifications of each reinforcing steel company or the swaging condition.

Further, in the present embodiment, at the time of the above-mentioned swaging, the boundary between the circumferential node (20) and the cylindrical body (10) is processed so as to maintain the shape of the original material, thereby suppressing the occurrence of cracks. Can be made more reliable.

Thus, the axis (19) of the cylindrical body (10) and the axis (59) of the swaging part (50) are aligned. In addition, the deformed protruding portions of the nodes (20) and the leaves (30) or the deformed bar steel can be straightened through this process.

Thereafter, as shown in FIG. 3C, the cross-section (53) of the connecting end protruded in the swaging process is cross-sectioned and chamfered, and the cross-section (53) is flattened to obtain a cross-section (53). The outer peripheral edge (55) is chamfered. In this way, it is intended to suppress screw damage at the corners when handling deformed steel bars and to improve the tightenability.

Next, FIG. 3D and FIG. 3E are state diagrams in which rolled screws have been machined at the connection ends of the deformed steel bars that have been swaged. Fig. 3D shows the shape of the thread when the transverse leave is located in the front direction. Although the outer peripheral surface of the swaging part (50) is rolled, the transverse leave (30) is used. The complete thread (60) is formed at the circumferential node (20) and the incomplete thread (61) is formed at the cylindrical body. FIG. 3E is a view showing the shape of the thread when the above-mentioned lateral leave is positioned on the upper side, and shows a state where a complete thread is machined into the joint portion and the cylindrical body surface. The outer diameter (64, 62) of the rolled screw portion (60, 61) is formed larger than the diameter (11) of the body θ). In this way, the thread (60, 61) of the deformed steel bar for concrete reinforcement processed according to the present invention is not cut, and the circumferential joint (20) and the lateral leave (30) are cooled. The mechanical strength is improved by inter-swinging and rolling thread processing, the metal structure becomes finer, and the internal structure including the cylindrical body (10) maintains its inherent structure, so high loads and impacts Also endure.

Table 1 below shows a comparative example of the tensile strength of the deformed steel bars processed according to the present invention and the corresponding deformed steel bars of the ASTM (US Industrial Standard) standard and the KS (Korean Industrial Standard) standard. [Table 1] Tensile strength (kgfZmm ² )

In this experiment, a tensile strength test was performed on 10 samples, and it can be seen that the tensile strength of the sample No. 3 in Reference 1 and the sample No. 5 in Reference 2 dropped sharply. It can be said that the fracture is caused by the notch after the processing, and it is understood that the fracture due to the notch does not occur in the present invention. As described above, when the complete screw and the incomplete screw are formed at the connection end of the deformed ^ 3, the coupler connecting the deformed bars does not need to be unnecessarily large, and usually the diameter of both deformed bars You may use a coupler that is 80% of the total length. In addition, since the internal hardened layer is generated only on the surface of the incompletely threaded portion, the processing is facilitated.

On the other hand, in this embodiment, an example in which the connection end of the deformed steel bar is swaged is presented, but the present invention is not limited to this. As an example, in the present invention, as shown in FIG. 5A and FIG. 5B, a rolled screw portion can be formed in a node (20 ′;) and a leave (30 ′) of the original material itself of the deformed bar. In this case, a coupler with a length greater than the sum of the diameters of both deformed steel bars must be used.However, when rolling threads are processed in the original material state, work hardening does not occur. Not only does this not only make it easier, but also there is no notch that adversely affects tensile strength.

FIGS. 8A and 8B show micrographs of the structure of the connection end portion of the deformed steel bar according to the present invention. Fig. 8A shows the metal structure along the axial direction of the deformed bar, and it can be seen that the continuity of the pearlite and ferrite structures shown in Fig. 7A appears more clearly and the structure becomes denser.

Fig. 8B shows the microstructure of the deformed bar in the direction perpendicular to the axis, which appears denser than the pearlite and ferrite microstructures in Fig. 7B.

In the above-mentioned rolling screw working in this embodiment, all kinds of screws such as a round screw and a triangular screw can be used, but it is preferable to work with a round screw. For example, a screw can be machined as shown in FIGS. 9A and 9B.

The reason is that when processing with a round screw, the cross section of the thread is rounded and the root part is formed thick like a trapezoidal screw, so the resistance is increased, and as a result, the notch phenomenon does not occur Of course, the strength is good and dust and sand can be easily fastened at many construction sites.

In addition, when the pitch of the above-mentioned round screw is made narrower, the tightening force and strength can be improved. Of course, there is no fear of loosening even if a lot of vibration is generated.

Then, as shown in FIG. 10, the diameter of the thread valley (65) at the boundary adjacent to the above-mentioned leave (30) and the joint (20) at the roll-formed thread (60) is changed to the other side. It is possible to suppress the stress concentration phenomenon by processing sequentially larger than the valley diameter (63).

FIG. 3A shows a deformed steel bar (100) for concrete reinforcement in which the leaves (30) and the nodes (20) are formed, but the present invention is not limited to this. Or it can also be applied to deformed steel bars for concrete reinforcement with leaves formed by X-rays.

FIGS. 11A to 11C show a method of connecting the deformed steel bars for concrete reinforcement of the present invention configured as described above. As shown in the drawing, the shape of the rolled thread (60, 61) corresponds to the shape of the rolled thread (60, 61) formed at the connection end of each deformed steel bar (100). The use of a coupler (200) having a nut part allows the threaded threaded parts formed at the odd-shaped connection ends to be interconnected.

The present invention described above is limited by the embodiments described above and the accompanying drawings. Various substitutions, modifications and alterations are possible without departing from the technical idea of the present invention without departing from the spirit of the present invention, and it is obvious to those skilled in the art to which the present invention belongs. It is. INDUSTRIAL APPLICABILITY According to the present invention described above, it is possible to work without destroying the reinforcing steel structure of the irregular connection end for concrete reinforcement used in construction and civil engineering sites, and to provide a mechanical connection to this connection part. Strength can be improved.

In particular, although the connection is formed by cold swaging and rolling, the threads are formed completely in the leaves and joints, and the incomplete threads are formed in the cylindrical body to maximize work hardening. By suppressing the above work hardening only on the cylindrical surface while suppressing the internal structure and maintaining the original structure of the original material as it is, the rolling process becomes very easy and the productivity is improved. Not only can this be done, but also the associated manufacturing costs. In particular, when processing with round screws, the fastening work is very easy, shortening the period and reducing the cost, and compared with the connection structure of the deformed steel bars manufactured by the conventional upset method, The advantage of maintaining the length is that it saves about 1-2% of the material.

Claims

The scope of the claims

1. Screws are formed only in the leaves and joints formed in a given section on at least one connection end side of a deformed steel bar having a lateral leave formed on the surface of the cylindrical body and a number of circumferential joints. Processing method of the connection end of deformed steel bar for concrete reinforcement.

2. At least one section of the deformed bar with a lateral leave and a number of circumferential nodes on the cylindrical body surface is swaged so that it can be plastically deformed at room temperature at a specified section on the connection end side. A first step in which the transverse leave and the circumferential knot have a diameter about a predetermined size larger than the diameter of the cylindrical body;

Threading a predetermined section on the connection end side of the swaged deformed steel bar 2nd stage

And a method of processing a connection end of a deformed steel bar for concrete reinforcement, including:

3. In paragraph 2,

The second stage is a method of processing the connection end of a deformed steel bar for concrete reinforcement, in which the leaves and joints are completely screwed and the cylindrical body is processed with incomplete screws.

4. In paragraph 2 or 3,

The first-stage swaging is performed by cold swaging, and the second-stage threading is performed by rolling, which is a method of processing a connection end of a deformed steel bar for concrete reinforcement.

5. In Paragraph 2 or Paragraph 3, in the first stage of swaging, the boundary between the cylindrical body and the lateral leave forms a rounded surface with a gentle curve. Processing method of the connection end.

6. In paragraph 2 or 3,

In the first stage, the connecting end of the deformed steel bar for concrete reinforcement in which the axis of the connecting end of the swaged deformed steel bar and the shaft of the deformed steel bar on which the leaves and nodes are formed is substantially concentric. Processing method.

7. In paragraph 2 or 3,

A method of processing a connection end portion of a deformed steel bar for concrete reinforcement, in which a side cross section of the connection end portion of the deformed steel bar that has undergone the first-stage swaging process is cut and chamfered.

8. In paragraph 2 or 3,

In the rolling forming step of the second step, the diameter of the thread valley at the boundary adjacent to any one of the leave, the knot, and the cylindrical body in the thread forming section is sequentially increased from the valley of the other side. Of connecting end of deformed steel bar for concrete reinforcement.

9. In paragraph 4,

Although the diameter of the cold swaged portion is squeezed by a predetermined size larger than the diameter of the cylindrical body, the squeezed portion of the circumferential node (H) is substantially in the original material state. A method of machining the connection end of a deformed steel bar for concrete reinforcement formed at 5% to 95% of one of the height or the height of the lateral rib (HI).

10. In a deformed steel bar for interconnecting a deformed steel bar in which a lateral leave and a number of circumferential nodes are formed on the cylindrical body surface,

A deformed steel bar for concrete reinforcement in which a thread is formed only in a lateral leave and a circumferential node formed in a predetermined section on at least one side end of the deformed steel bar.

11. In paragraph 10,

The threaded portion is a deformed steel bar for concrete reinforcement formed by rolling.

12. In paragraph 10 or 11,

A deformed steel bar for concrete reinforcement, wherein the length of the screw portion is longer than the length of the screw portion corresponding to the nominal diameter of the deformed steel bar by a predetermined length.

13. In a deformed bar for interconnecting deformed bars in which a lateral leave and a number of circumferential nodes are formed on the cylindrical body surface,

A predetermined section of at least one side end of the deformed steel bar is formed to be larger than a diameter of a cylindrical body surface by a predetermined size by swaging, but the swept lateral rib and the circumferential direction are formed. A deformed steel bar for concrete reinforcement with a threaded section formed at the joint.

14. In paragraph 13,

The threaded part is a deformed steel bar for concrete reinforcement, including a complete threaded part that is plastically worked on the surface of the ribs and nodes, and an incomplete threaded part that is plasticized on the cylindrical body surface.

15. In paragraph 13,

16. In any one of paragraphs 13 to 15,

A deformed steel bar for concrete reinforcement, wherein the length of the thread portion is substantially the same as the nominal diameter of the deformed steel bar.

17. In any one of paragraphs 13 to 15,

A deformed steel bar for concrete reinforcement, wherein the length of the thread portion is substantially the same as one of the diameter of the circumferential node or the lateral leave of the deformed steel bar.

18. In any one of paragraphs 13 to 15,

A deformed steel bar for concrete reinforcement, wherein the length of the screw portion includes at least two circumferential angle-shaped nodes of the deformed steel bar.

19.In any one of paragraphs 13 to 15,

Although the diameter of the cold swaged portion is squeezed by a predetermined size larger than the diameter of the cylindrical body, the squeezed portion of the circumferential node (H) is substantially in the original material state. A profiled steel bar for concrete reinforcement formed at 5% to 95% of either the height or the height of the transverse rib (HI).

20. In any one of paragraphs 13 to 15,

A deformed steel bar for concrete reinforcement, wherein the diameter of the thread valley at the boundary portion adjacent to the leave and the node is sequentially increased in the roll-formed screw portion.