KR20180135658A - Coupler for Connecting Screw Type Steel Reinforcement And Method for Manufacturing the Same - Google Patents

Abstract

The present invention relates to a coupler for a screw-type steel bar joint and a manufacturing method thereof. The coupler is manufactured by dividing the coupler in a multilayer (multi-ply) structures which are spirally coupled to each other in a thickness direction, and thus the coupler can be easily formed by using equipment having a small molding capacity. Even if a material having high yield strength is used, the internal circumferential surface and the external circumferential surface of the coupler can be processed in an accurate form. According to the present invention, the coupler for joining a screw-type steel bar, which is a coupler for connecting a screw-type steel bar having a spiral rib formed on an outer surface thereof, comprises: an inner body part having a pipe shape having both ends opened, and having a steel bar coupling screw thread in which a rib of the screw-type steel bar is spirally coupled to an inner circumferential surface; and at least one outer body part having a pipe body having both ends opened to be stacked in a thickness direction on the outer circumferential surface of the inner body part.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a coupler for a screw-

[0001] The present invention relates to a coupler for connecting reinforcing bars, and more particularly, to a coupler for connecting reinforcing bars, and more particularly to a coupler for connecting reinforcing bars, in which spiral ribs are formed on the outer surface, And a method of manufacturing the coupler.

Conventionally, in order to connect reinforcing bars for use in concrete structures in various construction sites, reinforcing bars are conventionally bundled and fixed in a double layer structure. However, in this reinforcing bar fixing method, an operator has to wire the reinforcing bars around the reinforcing bars a plurality of times The work is troublesome and the center of the reinforcing bar is not vertical and is not straight, but the strength of the wire is weak, so that it is easily broken and the connection state is released.

In order to solve these problems, reinforcing couplers (reinforcing couplers) have been developed and used to easily and firmly connect reinforcing bars by means other than wires.

These reinforced couplers include wedge type couplers, quick couplers, tapered jack couplers and screw type couplers. Since the conventional reinforced coupler is manufactured through machining, There is a disadvantage in that it consumes a large amount of time, and it takes a long time to perform a manufacturing operation by machining.

In order to solve such a problem, Japanese Patent Application No. 10-1680178 discloses a spiral-shaped coupling groove formed on an inner circumferential surface so as to form a thread-like reinforcing bar having a spiral rib formed on its outer surface, A manufacturing apparatus and a method for manufacturing a reinforcing coupler having surface projections for increasing the bonding strength are disclosed.

The manufacturing method of the patent includes a mandrel having spiral mountains and valleys corresponding to the coupling grooves on the inner circumferential surface of the coupler, a plurality of dice having spiral mountains and valleys corresponding to the spiral surface projections of the outer circumferential surface of the coupler, The mandrel is rotated in a direction opposite to the mandrel so that threads can be simultaneously formed on the inner circumferential surface and the outer circumferential surface of the coupler.

However, the manufacturing method of the above patent has the following problems.

First, screw type reinforcing bars should be formed higher than the breaking strength of reinforcing bars. Recently, the use of threaded reinforcing bars with a yield strength of 600 MPa by increasing the application of high tensile steels has been increasing. The thickness of the coupler should be designed to be more than a certain thickness.

When the thickness of the coupler becomes thick, a high molding pressure is required to form the coupler through the rolling process. In this case, the shape of the thread is not completely processed in the coupler material, and thus molding defects are likely to occur.

Secondly, when the coupler of the registered patent is manufactured by rolling the steel material, it can be manufactured through hot forming to be performed at a temperature higher than the recrystallization temperature of the steel material and cold forming to be performed at a temperature lower than the recrystallization temperature. In case of hot forming, if the mandrel is continuously molded at a temperature of 800 ° C or higher, the mandrel which processes the inner diameter side thread is exposed to the high temperature and high pressure environment, and its service life is short, so it is not bonded to mass production.

In case of cold forming, the flow stress of steel material increases and the pressure required for forming increases more than three times as compared with hot forming. Therefore, it is necessary to use equipment with large molding capacity, but it is difficult to mold with 80 ton class equipment manufactured in Korea.

Korean Registered Patent No. 10-1680178 (Registered on November 22, 2016) Japanese Patent Application Laid-Open No. 2003-239458 (published on Aug. 27, 2003)

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide an apparatus and a method for forming a coupler by dividing a coupler into a multi-layer structure The present invention also provides a coupler for manufacturing a threaded type reinforcing bar and a method of manufacturing the coupler, which can process the threads into an accurate shape on the inner and outer peripheral surfaces of the coupler even if a material having high tensile strength is used.

According to another aspect of the present invention, there is provided a coupler for connecting a threaded type reinforcing bar, the coupling coupler having a spiral rib formed on an outer surface thereof and having a tubular shape with open ends, An inner body portion having a reinforcing bar coupling thread formed by ribs of the threaded reinforcing bar; And at least one outer body part which is a tubular body of which both ends are opened and which is coupled to the outer circumferential surface of the inner body part in a laminated manner in the thickness direction.

Further, the present invention provides a method for manufacturing a coupler for screw-type reinforcing bars as described above,

(S1) rolling a steel bar coupling thread on the inner circumferential surface of the inner body part using a mandrel having an outer circumferential surface formed with a thread having a shape and pitch corresponding to the steel bar coupling thread of the inner body part;

(S2) machining the outer body portion; And

(S3) inserting the inner body part through one end of the outer body part and stacking them together;

The present invention also provides a method of manufacturing a coupler for a screw-type reinforced concrete coupling.

According to the present invention, since the body portion of the coupler has a multilayer structure of the inner body portion and the at least one outer body portion, the thickness of each body portion can be reduced.

Therefore, the molding pressure required for forming the body of the coupler is remarkably reduced, so that the coupler can be manufactured even with a small-capacity molding equipment, and the thread for coupling with the reinforcing bar can be processed into the correct shape on the surface of the coupler, The effect of significantly lowering the incidence rate can be obtained.

1 is a perspective view illustrating a coupler for a threaded type reinforcing bar according to an embodiment of the present invention.
2 is a cross-sectional view of the coupler shown in Fig.
3 is a cross-sectional view illustrating a threaded type reinforcing coupler according to another embodiment of the present invention.
4 is a cross-sectional view illustrating a coupler for a threaded type reinforcement according to another embodiment of the present invention.
5 is a perspective view showing an embodiment of an apparatus for manufacturing a screw-type reinforcing bar coupler according to the present invention.
FIG. 6 is a graph showing a change in load necessary for the step of forming the precursor according to the thickness variation of the coupler.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a screw-type reinforcing coupler and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show a coupler (hereinafter referred to as 'coupler') for threaded type reinforcing bars according to an embodiment of the present invention.

The coupler of the present invention is a coupler for connecting two threaded reinforcing bars B, each having a spiral rib R formed in a spiral shape along the axial direction, on the outer circumferential surface of the coupler. In the coupler according to an embodiment of the present invention, An inner body portion 110 having an opened tubular shape and an outer body portion 120 coupled to the outer peripheral surface of the inner body portion 110 so as to be laminated in the thickness direction. That is, the coupler of the present invention is formed of a multi-layered structure (multi-layer structure) in which a plurality of body portions of a cylindrical tube body are laminated in the thickness direction.

The inner body 110 has a cylindrical tubular shape with open ends at both ends thereof, so that both ends of the two threaded reinforcing bars B are inserted through both ends of the open end. A reinforcing bar coupling thread 111 is formed on the inner circumferential surface of the inner body part 110 such that a rib R of the threaded reinforcing bar B is spirally threaded along the axial direction. The reinforcing bar coupling threads 111 are formed in a spiral shape having the same shape and pitch as the spiral ribs R of the respective threaded reinforcing bars B. [

Male threads 112 are formed in a spiral shape along the axial direction on the outer circumferential surface of the inner body 110. The male thread 112 of the inner body 110 is formed for easy coupling with the outer body 120 and the male threads 112 are formed in the same shape and pitch as the bar coupling threads 111 But may be made of thread having a shape and pitch different from that of the reinforcing bar coupling thread 111. [

The outer body portion 120 has a cylindrical tube shape having both ends open and an inner diameter corresponding to the outer diameter of the inner body portion 110 so as to surround and be coupled to the outer side of the inner body portion 110. That is, the outer body part 120 is stacked and joined to the outer side of the inner body part 110. The outer body part 120 and the inner body part 110 are screwed together.

To this end, a female thread 121 is formed on the inner circumferential surface of the outer body portion 120 so as to be spirally formed along the axial direction. The female thread 121 is coupled with the male thread portion 112 of the outer circumferential surface of the inner body portion 110. The female thread 121 is formed of a thread having the same shape and pitch as the male thread 112.

Since the male thread 112 is formed on the outer peripheral surface of the inner body 110 and the female threads 121 corresponding to the male thread 112 are formed on the inner peripheral surface of the outer body 120, The male thread 112 and the female thread 121 are coupled to each other by spirally coupling one end of the outer body 120 to the one end of the inner body 110, So that it can be stacked on the outside.

On the outer circumferential surface of the outer body portion 120, surface projections 123 for increasing the contact area with the concrete placed outside the coupler are formed in a spiral shape along the axial direction. The surface protrusions 123 may be formed of threads having the same shape and pitch as those of the female threads 121. Alternatively, the surface protrusions 123 may have threads having different shapes and pitches from those of the female threads 121. [ By further forming the surface projection 123, the coupling strength with the concrete when the coupler 100 is embedded in the concrete can be further improved.

Of course, the surface protrusions 123 may not be formed in a spiral shape but may be protruded by a simple circular band shape or the like. However, when the surface protrusions 123 are formed in a spiral shape as described above, the surface protrusions 123 are also formed in the process of forming the female threads 121 on the inner circumferential surface of the outer body portion 120 through a single rolling process So that the manufacturing time can be shortened and the material cost can be reduced.

The surface protrusions 123 may be further formed with flat flat portions at regular intervals to facilitate engagement of wrenches such as spanners.

The coupler 100 of the present invention has a structure in which the body portion directly coupled to the threaded reinforcing bar B has a multi-layered structure of the inner body portion 110 and the outer body portion 120, The thickness of the body 120 can be reduced to about 1/2 of the conventional thickness. Therefore, when the inner body portion 110 and the outer body portion 120 are manufactured through the rolling process, the material can be easily formed using equipment having a small molding capacity. Even if a material having high tensile strength is used It is possible to process the inner and outer circumferential surfaces of the inner body 110 and the outer body 120 into an accurate shape.

The inner body 110 and the outer body 120 may have the same thickness but the thickness of the inner body 110 which is required to have a strong coupling force with the reinforcing bars is less than the thickness of the outer body 120 As shown in Fig. The sum of the thicknesses of the inner body portion 110 and the outer body portion 120 is substantially equal to the thickness of the body portion of the conventional single-layer coupler.

The outer body part 120 may be made of the same material as the inner body part 110, but may be made of different materials. For example, the inner body portion 110 may be made of a metal such as steel for rigid fixation of the reinforcing bars, and the outer body portion 120 may be made of a high strength plastic or ceramic material. Of course, conversely, the outer body portion 120 may be made of a material having a higher strength than the inner body portion 110.

Although the coupler 100 has a two-layer structure of the inner body 110 and the outer body 120 in the above-described embodiment, the outer body 120 may be formed as shown in another embodiment of FIG. Two or more layers may be sequentially laminated and coupled to form a multi-layered structure of three or more layers. In this case, the thicknesses of the inner body portion 110 and the outer body portion 120 can be reduced.

Also, when the outer body portion 120 is formed of two or more layers as in this embodiment, the male thread 122 and the female thread 121 are formed on the outer and inner circumferential surfaces of the respective outer body portions 120 So that the outer body parts 120 can be easily laminated to each other in a screwing manner.

A surface protrusion 123 for increasing the contact area with the concrete is also formed on the outer surface of the outer body part 120 stacked on the outermost one of the outer body parts 120 along the axial direction.

As described above, in the coupler 100 of the present invention, the inner body portion 110 and the outer body portion 120 are coupled while being laminated in a screw-type manner, and the threaded type reinforcing bars B are formed on the inner side of the inner body portion 110, Are coupled in a threaded manner. Therefore, when an external force is applied to the threaded reinforcing bar B and / or the outer body portion 120 in the circumferential direction, loosening occurs and bonding strength between the bars can be weakened.

4, a tapped hole 130 is formed to extend from an outer circumferential surface of the outer body portion 120 to an inner circumferential surface of the inner body portion 110, and a locking bolt (not shown) 140 can be fastened. The tapped hole (130) is formed as a through hole in which a thread is formed on the inner peripheral surface.

The locking bolt 140 is fastened to the tapped hole 130 so that the tip of the locking bolt 140 is inserted into the inner body 110 to press the outer surface of the threaded reinforcing bar B, And at the same time, the inner body 110 and the outer body 120 are fastened together to prevent loosening of each other.

Particularly, the locking bolt 140 is preferably made of a tongue bolt so as not to protrude out of the tapped hole 130.

Next, a method of manufacturing a coupler according to an embodiment of the present invention having the above-described structure will be described with reference to FIG.

First, a ferrule coupling thread 111 and a male thread 112 are simultaneously rolled on the inner peripheral surface and the outer peripheral surface of the inner body portion 110 by using the mandrel 300 and the plurality of rolling dies 210, 220, and 230 . The mandrel 300 has a circular rod shape formed on an outer circumferential surface thereof with threads having a shape and pitch corresponding to the reinforcing bar coupling threads 111 of the inner body portion 110, And is configured to be rotated by receiving the rotational driving force.

The rolling dies 210, 220 and 230 have a shape corresponding to the male thread 112 on the outer circumferential surface thereof and a shape corresponding to the male thread 112 on the outer circumferential surface thereof, Threaded portions 211, 221, and 231 are formed. Each of the rolling dies 210, 220 and 230 receives rotational driving force from a separate single rotation driving unit (not shown) while being positioned on the radial direction side of the mandrel 300, 300 in the opposite direction. Further, each of the rolling dies 210, 220 and 230 may be moved to a radial direction side by a separate die moving means so that the thread of the outer peripheral surface of each of the rolling dies 210, 220 and 230 may be contacted with and separated from the outer peripheral surface of the inner body 110 .

When it is desired to process the ferrule coupling threads 111 and the male thread 112 on the outer circumferential surface and the inner circumferential surface of the inner body portion 110 by using the mandrel 300 and the plurality of rolling dies 210, 220 and 230, , One end of the mandrel 300 is brought into contact with one end portion of the hollow portion of the inner body portion 110 made of a cylindrical tube body and the plurality of rolling dies 210, 220 and 230 are wound toward the inner body portion 110 The plurality of preprocessing dies 210, 220, and 230 are driven to rotate in the same direction with each other while the outer circumferential surface of the mandrel 300 moves to abut the outer circumferential surface of the inner body 110, 220 and 230. The reinforcing bar coupling thread 111 is formed on the inner peripheral surface of the inner body portion 110 and the outer peripheral surface of the inner body portion 110 is formed in the outer peripheral surface of the inner body portion 110, A number for the helical coupling with the part 120 And processing the dinitrogen 112.

When the mandrel 300 and the plurality of rolling dies 210, 220, and 230 are rotated and pressed in opposite directions to each other, a thread is simultaneously machined on the inner and outer circumferential surfaces of the inner body 110 to minimize waste of the material There is an advantage that the total manufacturing time can be shortened.

The female thread 121 and the male thread 112 or the surface projection 123 are processed on the inner and outer circumferential surfaces of the outer body portion 120 in the same manner after the inner body portion 110 is machined as described above. That is, a mandrel (not shown) for processing a female thread in which a thread having a shape and pitch corresponding to that of the male thread 112 on the outer peripheral face of the inner body 110 is formed is inserted into one end of the inner peripheral face of the outer body 120 A plurality of preprocessing dies (not shown) are arranged so as to be connected to the outside of the outer body portion 120, and the plurality of preprocessing dies are driven to rotate in the same direction with each other, The mandrel is driven to rotate in a direction opposite to the dicing die for machining so that the female thread 121 is machined on the inner peripheral surface of the outer body portion 120 and the male thread 122 or the surface The protrusions 123 are simultaneously processed.

In the above-described embodiment, the inner body 110 is first rolled and the outer body 120 is rolled, but the outer body 120 is rolled first and the inner body 110 is later rolled It is needless to say that the rolling process may be performed.

When the outer body part 120 is made of high-strength plastic, the outer body part 120 may be manufactured by injection molding or extrusion molding without passing through the rolling process.

When the inner body 110 and the outer body 120 are machined and one end of the inner body 110 is rotated relative to the one end of the outer body 120, The male thread 112 is coupled to the female thread 121 of the outer body 120 and the inner body 110 is inserted into the outer body 120 and stacked.

When the outer body portion 120 is composed of a plurality of the outer body portions 120, the outer body portions 120 are coupled to each other in the same manner to manufacture the coupler body portion in a multi-layered structure.

FIG. 6 is a graph showing a change in load required for the preforming process according to the thickness variation of the coupler. It can be confirmed that the molding pressure increases as the thickness is increased to 2t and 3t when the thickness is 1t as a reference load. Therefore, if the coupler 100 is constructed in a multi-layered structure of the inner body 110 and the at least one outer body 120 as in the present invention, the molding pressure required to form the respective body portions is remarkably small, It is possible to manufacture the coupler even with the capacity molding equipment and it is possible to process the reinforcing bar coupling thread 111 for coupling with the reinforcing bar to the surface of the coupler in an accurate shape,

Further, in order to improve the fastening strength with the threaded reinforcing bar, a material having higher strength may be applied to the inner body portion 110 or the outer body portion 120, and the thickness may be made thinner in order to prevent deterioration of the formability Couplers can be manufactured with various materials and thicknesses as required.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention.

B: Threaded reinforcing bar R: Rib
100: coupler 110: inner body part
111: Reinforced coupling thread 112:
120: outer body part 121: female thread
122: male threads 123: surface projection
130: Tapped hole 140: Locking bolt

Claims (11)

In a coupler for connecting a threaded reinforcing bar (B) having a rib (R) formed in a spiral shape on its outer surface,
An inner body 110 having a tubular shape with open ends at both ends and having an inner circumferential surface formed with a reinforcing barrel thread 111 to which a rib R of the threaded reinforcing bar B is screwed;
And at least one outer body part (120) which is a tubular body with both ends opened and which is coupled to the outer circumferential surface of the inner body part (110) in a laminated manner in the thickness direction. The male threaded member according to claim 1, wherein a male thread (112) is formed in a spiral shape along an axial direction on an outer circumferential surface of the inner body portion (110) Wherein the female threads (121) are formed in a spiral shape along the axial direction. [3] The apparatus according to claim 2, wherein at least two of the outer body parts (120) are stacked in order, and the outer body parts (120) Wherein the male thread (122) and the female thread (121) are formed in a spiral shape along the axial direction. [3] The method according to claim 1, wherein a surface projection (123) for increasing a contact area with concrete placed outside the coupler is formed on an outer surface of an outer body part (120) stacked on the outermost one of the outer body parts (120) Wherein the coupler is formed in a spiral shape along the first direction. The screw coupling coupler of claim 1, wherein the inner body portion (110) and the outer body portion (120) are made of different materials. The screw coupling coupler of claim 1, wherein the inner body portion (110) and the outer body portion (120) are made of different materials. The connector according to claim 1, wherein a tapped hole (130) is formed to extend from an outer circumferential surface of the outer body portion (120) to an inner circumferential surface of the inner body portion (110), and a locking bolt Wherein the coupler is a screw-type reinforcing coupler. 8. A method of manufacturing a threaded type reinforcing coupler according to any one of claims 1 to 7,
The inner circumferential surface of the inner body portion 110 is formed with a reinforcing engagement thread 111 on the outer circumferential surface of the inner body portion 110 by using a mandrel 300 having a thread having a shape and pitch corresponding to the reinforcing bar coupling threads 111 of the inner body portion 110, (111);
(S2) machining the outer body portion 120; And
(S3) inserting the inner body part 110 through one end of the outer body part 120 and stacking them;
Wherein the coupler is formed of a metal. The method according to claim 8, wherein in step S1, a plurality of preprocessing dies (210, 220, 230) are arranged in a continuous manner on the outer side of the inner body part (110) And the mandrel 300 is driven to rotate in the direction opposite to the dies 210, 220 and 230 for the rolling of the mandrels so that the inner peripheral surface of the inner body 110 is connected to the reinforcing threads 111 And a male screw thread 112 is formed on an outer circumferential surface of the inner body part 110 for screw engagement with the outer body part 120. The method of claim 1, The method as claimed in claim 9, wherein in step (S2), a male thread forming mandrel having a shape and a pitch corresponding to the male threads (112) of the outer circumferential surface of the inner body (110) And a plurality of preprocessing dies are arranged so as to be connected to the outside of the outer body portion 120 so that the plurality of preprocessing dies are driven to rotate in the same direction with each other, The female thread 121 is machined on the inner circumferential surface of the outer body portion and the male thread 122 or the surface protrusion 123 is formed on the outer circumferential surface of the outer body portion 120 Wherein the method comprises the steps of: 9. The method of claim 8, wherein the inner body portion (110) and the outer body portion (120) are manufactured using cylindrical materials of different materials.

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