JP2012110919A - Device and method of manufacturing mechanical joint of reinforcing bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for manufacturing a mechanical joint of a reinforcing bar, and to provide a technology for enhancing strength of the mechanical joint by plastic working.SOLUTION: The method executes a process of pushing a work W1 into a die 42 by a punch 32 by using a pressing machine having the punch 32 for pressing the work W1 with a core bar 5 inserted therein, the die 42 having a molding hole 42a formed of a large diameter part 421 and a small diameter part 422 and in which the punch 32 plunges together with the work W1, and a knockout 46 which plunges in the molding hole in conjunction with the punch 32, and the core bar 5 having a core bar pin 54 which is inserted in a through hole of the work W1 and receives pressing force from the knockout 46; a process of pushing out the core bar 5 from a through hole of a work W2 by pressing the core bar pin 54 of the core bar 5 protruded from an opening end of the through hole of the work W1 by the knockout 46; and a process of pushing out the work W2 pressed in the die 42 to an outside of the die 42 by the knockout 46.

Description

  The present invention relates to a technique for manufacturing a mechanical joint of a reinforcing bar, and more particularly to a technique for reducing the diameter of a cylindrical workpiece.

  When a high tensile strength is required for a reinforcing bar such as a high-rise building, a high-strength reinforcing bar with a large diameter is used, and a mechanical coupling is most often used as a reinforcing bar joint. In reinforced concrete construction, reinforcing bars are mainly used to resist tensile forces, so that the mechanical joints themselves are required to have a very high tensile strength.

  In this regard, in Patent Document 1, the applicant of the present application is a cylindrical mechanical joint as a connecting structure of a reinforcing bar by a mechanical joint, and the reinforcing bar is inserted into one end side and integrated by cold pressure bonding, and the other end portion. One having an insertion hole in which a female screw is formed on the side has been proposed. These mechanical joints connect the reinforcing bars in pairs, and the female thread sides of the insertion holes of the pair of mechanical joints face each other, and male threads are formed on the outer peripheral surface of each female thread part. Screw in the connection bolt. Thereby, a reinforcing bar is connected.

Japanese Patent Laid-Open No. 10-037384

  Although the mechanical joint described in Patent Document 1 has a large tensile strength, a technique for manufacturing such a mechanical joint has not been disclosed so far. In addition, a technique for increasing the strength of a mechanical joint by performing plastic working at the time of manufacture has not been disclosed so far.

  Then, an object of this invention is to provide the technique which raises the intensity | strength of a mechanical joint by performing the plastic working and the technique which manufactures the mechanical joint of a reinforcing bar.

  In order to achieve the above object, a rebar mechanical joint manufacturing apparatus according to one aspect of the present invention inserts a rebar inside by reducing the diameter of a cylindrical workpiece in which a through hole is formed. An apparatus for manufacturing a mechanical joint of a reinforcing bar that has a through hole for processing and is plastically processed radially inward, and a press machine that performs plastic processing on the workpiece, and an approximate plug that is inserted into the through hole of the workpiece A punch that presses the workpiece into which the mandrel is inserted, and a hole with a certain length into which the punch enters together with the workpiece, The inner diameter is substantially the same as the outer diameter of the workpiece, the large-diameter portion formed on the punch side, and the inner diameter is smaller than the outer diameter of the workpiece, and faces the punch across the large-diameter portion. A die having a molding hole made of a small diameter portion formed on the side to be A knockout that is arranged on the side facing the punch with the forming hole interposed therebetween and that projects into the forming hole in conjunction with the punch, and has an outer diameter that is an insertion hole of the workpiece And the length in the axial direction is longer than the axial length of the through hole of the manufactured mechanical joint, and is inserted into the through hole of the work. An end portion extending from the through hole to the knockout side has a mandrel pin that receives a pressing force from the knockout.

  The mandrel further includes a head that is sandwiched between the work and the punch and receives a pressing force from a punch that enters the die, and the mandrel pin expands and contracts in the axial direction. It is good also as what is attached to the said head through the spring which carries out.

  The head is formed with a claw portion that is hooked to the edge of the insertion hole of the workpiece and positions the mandrel at a position where the axial center coincides with the center of the insertion hole. Also good.

  The manufactured reinforcing steel mechanical joint has an inner peripheral surface formed with a male screw on the outer peripheral surface and a female screw for screwing a bolt connecting a pair of mechanical joints. The diameter of the mandrel pin may be the lower diameter of the female screw formed in the through hole.

  Further, the mandrel pin of the mandrel may have a surface coated with a wear resistant material or subjected to a wear resistant treatment.

  The mandrel pin of the mandrel may be formed with a taper whose diameter decreases toward the knockout side.

  In addition, a method for manufacturing a mechanical joint for reinforcing bars according to another aspect of the present invention includes a through hole for inserting a reinforcing bar into the inside by reducing the diameter of a cylindrical workpiece having the through hole formed therein. A punch that presses the workpiece into which the mandrel is inserted, and a fixed length that the punch enters together with the workpiece. The inner diameter is substantially the same as the outer diameter of the workpiece, the larger diameter portion formed on the punch side, and the inner diameter is smaller than the outer diameter of the workpiece. A die having a molding hole composed of a small-diameter portion formed on the side facing the punch across the diameter portion and a side facing the punch across the molding hole are arranged in conjunction with the punch. A knockout that enters the forming hole, and a press machine having The outer diameter is smaller than the diameter of the through hole of the workpiece, the axial length is longer than the axial length of the through hole of the manufactured mechanical joint, and the workpiece penetrates. The end portion extending from the insertion hole of the workpiece to the knockout side is inserted into the insertion hole, and the mandrel having the mandrel pin that receives the pressing force from the knockout, the punch, the punch By pushing the work into the die and the knockout, the mandrel pin of the mandrel protruding from the open end of the insertion hole of the work is pressed, and the mandrel is penetrated through the work. The step of pushing out from the insertion hole and the step of pushing out the work pushed into the die by the knockout to the outside of the die are performed.

  According to the present invention, it is possible to manufacture a rebar mechanical joint that is subjected to plastic working during manufacturing and has increased strength.

In a manufacturing apparatus and a manufacturing method for a mechanical joint of a reinforcing bar according to an embodiment of the present invention, (a) a work before processing, (b) a work partially reduced in diameter, (c) a mechanical joint as a finished product, FIG. It is sectional drawing which shows the structure of the press machine which comprises the manufacturing apparatus of the mechanical coupling of the reinforcing bar which concerns on this embodiment. It is sectional drawing which shows the mandrel which comprises the manufacturing apparatus of the reinforcement mechanical joint which concerns on this embodiment. It is sectional drawing which shows the first stand-by state among a series of processes performed by the manufacturing apparatus and the manufacturing method of the reinforcing steel mechanical joint which concern on this embodiment. It is sectional drawing which shows the state by which the workpiece | work was pushed in into die | dye with a punch in the series of processes performed by the manufacturing apparatus and the manufacturing method of the rebar mechanical joint which concern on this embodiment. It is a partial expanded sectional view which shows a mode that a workpiece | work is pushed in into die | dye by a punch among the series of processes performed by the manufacturing apparatus and the manufacturing method of the rebar mechanical joint which concern on this embodiment, (a) The state before being pushed in, (b) the state pushed in, is shown. It is a partial expanded sectional view which shows a mode that a workpiece | work is extruded out of die | dye by a punch among the series of processes performed by the manufacturing apparatus and the manufacturing method of the rebar mechanical joint which concern on this embodiment, (a) A state where the mandrel is pushed out of the workpiece, (b) a state where the workpiece is pushed out of the die.

Next, a rebar mechanical joint manufacturing apparatus and a rebar mechanical joint manufacturing method according to an embodiment of the present invention will be described with reference to the drawings.
First, in FIG. 1, a rebar mechanical joint manufacturing apparatus and a rebar mechanical joint manufacturing method according to the present embodiment, a work W1 subjected to diameter reduction processing, a work W2 subjected to diameter reduction processing, and a final The mechanical joint W3 manufactured is shown in FIG.

As shown in FIG. 1 (a), the workpiece W1 before being processed by the rebar mechanical joint manufacturing apparatus according to the present embodiment is formed in a cylindrical shape, and the through-hole 11 having both ends opened therein is provided inside. In preparation. The workpiece W1 is made of a metal material such as iron.
Moreover, the manufacturing apparatus and the manufacturing method of the mechanical joint of a reinforcing bar according to the present embodiment perform a diameter reduction process for reducing the diameter of a part of the workpiece W1, and as illustrated in FIG. The processed workpiece W2 is reduced in diameter at one end portion from the approximate center as compared with the other end side (hereinafter, the reduced diameter portion is referred to as a small diameter portion 12, and the non-reduced portion is referred to as a large diameter portion 13). And).
Further, as shown in FIG. 1C, a female screw 12a is formed on the inner peripheral surface of the through hole 11 of the small diameter portion 12, and a mechanical joint W3 as a finished product is obtained.

When rebars are connected using this mechanical joint W3, a pair of mechanical joints W3 and a substantially cylindrical bolt having male threads that are threadedly engaged with the female threads 12a are prepared. And while inserting a reinforcing bar in the penetration hole 11 of the large diameter part 13 of each mechanical coupling W3, and integrating by cold crimping process, the small diameter part 12 of both mechanical couplings W3 is made to face each other, One end of the bolt is screwed into the through hole 11 of the small diameter portion 12, and the other end of the bolt is screwed into the through hole 11 of the small diameter portion 12 of another reinforcing bar.
As a result, the reinforcing bars are connected by the pair of mechanical joints 3.

Next, an apparatus for manufacturing a mechanical joint for reinforcing bars according to this embodiment will be described.
The apparatus for manufacturing a mechanical joint for reinforcing bars according to this embodiment includes a press machine 2 and a mandrel 5. First, the press machine 2 is shown in FIG. 1.
The press machine 2 includes an upper base 3 that moves up and down and a lower base 4 that is fixedly installed.

  The upper base 3 includes a punch plate 31, a punch 32, a punch holder 33, a punch fastening fitting 34, a plane guide 35, a knockout coupling joint 36, a knockout receiving fitting 37, and a knockout adjustment screw 38.

On the other hand, the lower base 4 includes a die plate 41, a die 42, a die holder 43, a die fastening metal fitting 44, and a knockout guide flange 45.
Further, a knockout 46 is inserted into an insertion hole 45a formed in the knockout guide flange 45 so as to be slidable in the vertical direction.

As shown in FIG. 5, the punch 32 presses the mandrel 5 inserted into the work W1 to push the work W1 into the die 42.
The punch 32 includes a cylindrical pressing portion 32a and a flange 32b provided on one end side of the pressing portion 32a.

  The pressing portion 32 a has an outer diameter slightly smaller than the diameter of the forming hole 42 a of the cylindrical portion 421 of the die 42, and enters the die 42 according to the vertical movement of the upper base 3. As shown in FIG. 5, when the workpiece W1 is pushed into the die 42, the pressing portion 32a abuts against the head 51 of the mandrel 5 inserted into the through hole 11 of the workpiece W1 and applies a pressing force. Then, it enters the die 42 together with the work W1.

  The flange 32 b is engaged with an engagement groove 33 a formed by the punch holder 33 and the punch tightening fitting 34, whereby the punch 32 is fixed to the punch plate 31.

The punch holder 33 is attached to the punch plate 31.
The punch holder 33 has a punch fastening fitting 34 and an engaging groove 33a formed at the lower end thereof, and the punch 32 is fixedly held by engaging the flange 32b of the punch 32 with the engaging groove 33a. The punch plate 31 and the punch 32 are interlocked.

The punch fastening bracket 34 fastens the punch 32 to restrict horizontal movement, and positions the punch 32 on the forming hole 42 a of the die 42.
In addition, the punch tightening fitting 34 has a punch holder 33 and an engagement groove 33a formed at the upper end, and the punch 32 is attached to the punch plate 31 by engaging the flange 32b of the punch 32 with the engagement groove 33a. Fixed.

  The plain guide 35 includes a shaft 35a attached on the punch plate 31 and a bush 35b attached to the die plate 41. For example, the shaft 35a moves up and down using a motor (not shown) as a drive source, whereby the plane guide 35 moves the upper base 3 up and down.

The knockout coupling joint 36 couples the punch plate 31 and the knockout bracket 37.
The knockout bracket 37 moves up and down in conjunction with the punch plate 31 via the knockout coupling joint 36. The knockout metal fitting 37 is formed with a screw hole 37a having both ends opened in the vertical direction and an internal thread formed on the inner peripheral surface. A knockout adjusting screw 38 is screwed into the screw hole 37a.

The knockout adjustment screw 38 is a substantially rod-shaped member having a male screw formed on the outer peripheral surface thereof, and is screwed into a female screw formed on the inner peripheral surface of the screw hole 37a of the knockout bracket 37. Attached to the knockout bracket 37.
The knockout adjusting screw 38 and the knockout 46 have axial axes that are on the same straight line, and the upper end portion of the knockout adjusting screw 38 abuts on the lower end portion of the knockout 46 when the upper base 3 is raised by a certain distance. The knockout 46 can be moved up and down in accordance with the vertical movement of the adjusting screw 38.
Further, the knockout adjusting screw 38 can be rotated to adjust the mounting position in the vertical direction along the female screw formed on the inner peripheral surface of the screw hole 37a. By adjusting the mounting position in the vertical direction, the width of the vertical movement of the knockout 46 can be adjusted.

  The die plate 41 is a disk-shaped base for installing the die 42, and an insertion hole 41 a for inserting the knockout 46 is formed at the center. The die plate 41 has a die holder 43 on the upper surface side and a lower surface on the lower surface side so that the centers of the insertion hole 41a of the die plate 41, the insertion hole 43a of the die holder 43, and the insertion hole 45a of the knockout guide flange 45 coincide. A knockout guide flange 45 is attached.

The die 42 is a mold for molding the workpiece W1, and is a cylindrical member provided with a molding hole 42a for molding the workpiece W1 therein.
The die 42 includes a cylindrical portion 421 on the punch 32 side and a reduced diameter portion 422 on the knockout 46 side.
In the cylindrical portion 421, the inner forming hole 42a has substantially the same diameter as the outer diameter of the workpiece W1. The diameter of the forming hole 42a of the cylindrical portion 421 may be configured to be slightly smaller than the outer diameter of the work W1, and in this case, the work W1 is pushed into the forming hole 42a of the cylindrical portion 421 by the punch 32. In this case, a slight error in the outer diameter due to individual differences of the workpiece W1 can be adjusted.
Further, the reduced diameter portion 422 is formed such that the diameter of the inner forming hole 42 a is smaller than the diameter of the forming hole 42 a of the cylindrical portion 421. More specifically, from the boundary portion with the cylindrical portion 421, a portion that gradually decreases in diameter to be slightly larger than the outer diameter of the small-diameter portion 12 of the workpiece W2, and a portion that is maintained at a certain distance from the reduced diameter And a portion that gradually increases in diameter toward the opening side into which the knockout 46 enters.

  The die holder 43 is a member for holding the die 42 on the die plate 41 and fixes the die plate 41 and the die 42 integrally. The die holder 43 is formed with an insertion hole 43a through which the knockout 46 is inserted at the center.

  The die fastening metal fitting 44 is attached to the opening end portion of the die 42, and fastens and stably fixes the die 42. The die fastening bracket 44 is formed with an insertion hole 44a for inserting the punch 32 in the center.

The knockout guide flange 45 is attached in the vicinity of the insertion hole 41a of the die plate 41. In the center thereof, the knockout guide flange 45 is slightly larger than the outer diameter of the axial center portion of the knockout 46 and larger than the diameter of the head portion of the knockout 46. An insertion hole 45a having a small diameter is formed.
The insertion hole 45a of the knockout guide flange 45, the insertion hole 41a of the die plate 41, the insertion hole 43a of the die holder 43, and the molding hole 42a of the die 42 are all in a straight line, and the knockout 46 is knocked out as the upper base 3 is raised. It is guided by the guide flange 45 and enters the die 42.

The knockout 46 is a rod-like member having a substantially T-shaped cross section, which is composed of an axial center portion 46a and a head portion 46b. The flat circular head portion 46 b is configured so that its diameter is slightly smaller than the diameter of the through hole 11 of the reduced diameter portion 422 of the die 42.
The knockout 46 moves up and down in response to the vertical movement of the knockout adjustment screw 38. During the vertical movement, the knockout 46 is guided by the knockout guide flange 45 and enters the die 42 from below to push the workpiece W2 in the die 42 out of the die 42.

Next, the mandrel 5 used together with the press machine 2 will be described with reference to FIG.
The mandrel 5 is a member that is used by being inserted into the through hole 11 of the workpiece W1 when the workpiece W1 is processed by the press machine 2, and includes a head 51, a cap screw 52, a spring 53, and a mandrel pin 54. It consists of.

The head 51 is a cylindrical member attached to one end side of the mandrel pin 54.
The head 51 has an outer diameter substantially the same as the outer diameter of the workpiece W1, and when the mandrel 5 is inserted into the through hole 11 of the workpiece W1, the edge of the opening end of the head 51 is The head 51 is caught on the edge of W1 and cannot be inserted into the workpiece W1.
Further, as will be described later, the head 51 has a gap 512 opened at one end, and a claw portion 511 that gradually protrudes radially inward is formed at the edge of the opening end. ing. When the mandrel 5 is inserted into the insertion hole 11 of the workpiece W1, the claw portion 511 is hooked on the edge of the insertion hole 11, and the axis of the mandrel 5 and the center of the insertion hole 11 of the workpiece W1 The mandrel 5 is positioned on the workpiece W1 so that the two match.

In addition, a substantially cylindrical gap 512 having one end opened is formed inside the head 51, and the cap screw 52 is held by the gap 512.
The gap 512 is formed with a protrusion 513 that protrudes radially inward from the inner wall, whereby the gap 512 is composed of a gap 512a on the back side of the protrusion 513 and a gap 512b on the opening side. Yes.

A head 52b of the cap screw 52 is fitted into the gap 512a so as to be slidable in the axial direction. The diameter of the head 52b of the cap screw 52 is configured to be slightly smaller than the inner diameter of the gap 512a and larger than the inner diameter formed by the protrusion 513, and cannot be pulled out of the gap 512a by the protrusion 513. It is configured.
A spring 53 is sandwiched between the protrusion 513 and the head 52b of the cap screw 52, and urges the cap screw 52 toward the closed end (back side) of the gap 512a.

A mandrel pin 54 is fitted into the gap 512b so as to be slidable in the axial direction from the opening.
The mandrel pin 54 is a substantially rod-shaped member, and includes a large-diameter portion 54a, a small-diameter portion 54b, and a tip portion 54c. Note that, at the boundary between the large diameter portion 54a and the small diameter portion 54b, the diameter gradually decreases from the large diameter portion 54a to the small diameter portion 54b.
The outer diameter of the large diameter part 54a is slightly smaller than the inner diameter of the gap 512b, and a part of the large diameter part 54a is slidably fitted into the gap 512b. Moreover, the outer diameter of the large diameter part 54a is comprised smaller than the diameter of the penetration hole 11 of the workpiece | work W1, and it is comprised so that insertion to the penetration hole 11 of the workpiece | work W1 is possible.

Furthermore, a fitting hole 54d opened to one end side is formed inside the large diameter portion 54a.
A female screw is cut on the inner peripheral surface of the fitting hole 54 d and is screwed to a male screw formed on the outer peripheral surface of the shaft center portion 52 a of the cap screw 52.

The small diameter portion 54b is tapered so that the diameter gradually decreases toward the distal end portion 54c.
The outer diameter of the small diameter portion 54b is configured to be slightly smaller than the inner diameter of the insertion hole 11 of the small diameter portion 12 of the work W2, and the work W1 is reduced in diameter according to the outer diameter of the small diameter portion 54b. .

The distal end portion 54c constitutes a distal end portion when the mandrel 5 is inserted into the insertion hole 11 of the workpiece W1.
The tip portion 54c is tapered so that the diameter decreases from the boundary with the small diameter portion 54b toward the tip.
By forming the taper in this way, it is easy to insert the mandrel 5 into the through hole 11 of the workpiece W1.

  The surface of the mandrel pin 54 is coated with a wear-resistant material such as hard chrome plating, nitriding, titanium carbide coating, titanium nitride coating, aluminum nitride titanium coating, diamond-like carbon coating or the like. Wear processing is performed, and smoothness and hardness are maintained.

Further, when the mandrel pin 54 is inserted into the insertion hole 11 of the workpiece W1, the claw portion 511 formed in the head 51 is hooked on the edge of the insertion hole 11, and the axial center of the pin 51 is on the workpiece W1. It exactly coincides with the center of the through hole 11. Therefore, the through hole 11 of the reduced diameter portion 12 of the workpiece W2 obtained by reducing the diameter of the workpiece W1 has an accurate circular shape with no bias in thickness in the circumferential direction and no distortion in the inner diameter and outer diameter. Constitute.
Since the diameter can be reduced with high accuracy in this way, the diameter of the small diameter portion 54b of the mandrel pin 54 is made to correspond to the lower diameter of the female screw 12a formed in the insertion hole 11 of the workpiece W2. Thus, the diameter of the through hole 11 of the reduced diameter portion 12 of the workpiece W2 can be formed to be the same as the lower diameter of the female screw 12a. In this case, since it is not necessary to perform drilling as a pre-process for forming the female screw 42a, it is possible to form the reduced-diameter through hole 11 with high accuracy and strength, and to perform cutting by drilling. No powder is generated. Further, the diameter of the through-hole 11 is formed to be the same as the lower diameter of the female screw 42a by the diameter reduction process using the mandrel 5, and the surplus that is conventionally discarded as a chip by drilling. Can be used for extending the workpiece 1 itself. As a result, the workpiece W2 having a desired length can be obtained from the workpiece W1 shorter than the conventional one, and there is no waste of material, which is effective in cost reduction.

The cap screw 52 is a planar circular substantially rod-shaped member, and includes an axial center part 52a and a head part 52b having a larger diameter than the axial center part 52a.
The head 52b of the cap screw 52 is slidably fitted in the gap 512a of the head 51. In addition, a male screw is formed on the outer peripheral surface of the shaft center portion 52 a and is screwed into a female screw formed on the inner peripheral surface of the fitting hole 54 d of the mandrel pin 54. When the shaft center portion 52a and the fitting hole 54d are screwed together, the cap screw 52 and the mandrel pin 54 operate integrally.

  The mandrel 5 having the above-described configuration has the mandrel pin 54 screwed together when the mandrel pin 54 is pulled to the side facing the head 51 with the head 51 fixed. And the cap screw 52 are pulled out of the gap 512 against the urging force of the spring 53.

Then, the manufacturing method of the mechanical coupling which concerns on this embodiment is demonstrated.
First, at the start of processing, as shown in FIG. 4, the press machine 2 stands by with the upper base 3 positioned at the top dead center and the punch 32 separated from the die 42.
The knockout 46 is also pushed up to the upper end position. At this time, the upper end surface of the knockout 46 is at a position lower than the upper end surface of the die fastening metal fitting 44.
Further, when a part of the workpiece W1 is fitted into the molding hole 42a of the die 42 from the insertion hole 44a of the die fastening metal fitting 44, the cylinder of the die 42 having a diameter substantially the same as or slightly smaller than the outer diameter of the workpiece W1. The workpiece W1 is caught in the molding hole 42a of the portion 421, and the workpiece W1 can be held in a state where it does not fall over.

  As described above, when the mandrel 5 is inserted into the through hole 11 of the workpiece W1 and the workpiece W1 is placed on the die 42, the upper base 3 is lowered. When the upper base 3 is lowered, the knockout 46 and the punch 32 start to descend.

When the upper base 3 is further lowered, as shown in FIG. 5, the punch 32 comes into contact with the head 51 of the mandrel 5 inserted into the workpiece W1, and starts to push the workpiece W1 into the molding hole 42a of the die 42. .
As a result, the diameter of the workpiece W1 is reduced to the shape of the forming hole 42a of the reduced diameter portion 422 of the die 42.

Here, the diameter reduction process of the workpiece W1 is shown in FIG.
As shown in FIG. 6A, the cap screw 52 of the mandrel 5 is in the upper end position under the urging force of the spring 53 before the diameter is reduced.
On the other hand, when the punch 32 starts to push the workpiece W1 into the forming hole 42a of the reduced diameter portion 422 of the die 42, the workpiece W1 is reduced in the reduced diameter portion 422 of the die 42 as shown in FIG. The diameter is reduced according to the shape of the inner wall of the molding hole 42 a and the outer peripheral shape of the mandrel pin 54. At this time, the reduced diameter portion of the workpiece W1 is configured such that the distance between the outer peripheral surface of the mandrel pin 54 and the inner wall of the molding hole 42a of the reduced diameter portion 422 of the die 42 is smaller than the thickness of the workpiece W1. Therefore, it is crimped to the mandrel pin 54 and extends in the end direction (downward direction in the figure). As described above, when the reduced diameter portion of the work W1 is expanded in the end portion direction in a state where the work W1 is crimped to the mandrel pin 54, the mandrel pin 54 is also pulled in the extending direction of the work W1. Together with the cap screw 52 fitted together, the spring 53 is pulled out of the gap 512 against the biasing force of the spring 53.

When the upper base 3 is lowered as described above to reduce the diameter of a predetermined portion of the workpiece W1 to obtain the workpiece W2, the upper base 3 is raised and the workpiece W2 is extracted from the die 42.
As shown in FIG. 7A, when the upper base 3 is raised, the punch 32 is separated from the workpiece W2. At the same time, the knockout 46 again enters the molding hole 42a of the die 42.

Here, the knockout 46 that has entered the molding hole 42 a of the die 42 first comes into contact with the mandrel pin 54 of the mandrel 5 and applies an upward pressing force to the mandrel pin 54.
At this time, the small-diameter portion 12 of the workpiece W2 is more strongly pressed to the inner wall of the molding hole 42a of the die 42 than the mandrel pin 54, the mandrel pin 54 is coated with a wear-resistant material, or Since the wear treatment is performed, the friction between the mandrel pin 24 and the inner peripheral surface of the insertion hole 11 of the workpiece W2 is small, and the biasing force of the spring 53 acts, so FIG. ), The mandrel pin 54 pressed by the knockout 46 is retracted into the gap 512 while the workpiece W2 remains in the forming hole 42a of the reduced diameter portion 422 of the die 42. When the mandrel pin 54 is retracted into the gap 512, the mandrel pin 54 is formed on the small diameter portion 54b of the mandrel pin 54 with a taper that decreases in diameter toward the tip 54c. It leaves | separates from the inner wall of the penetration hole 11. FIG.

When the upper base 3 is further raised from here, the upper end surface of the knockout 46 comes into contact with the lower end surface of the workpiece W2, and the knockout 46 starts to press the workpiece W2 upward.
As a result, the workpiece W2 is pushed out of the forming hole 42a of the die 42 as shown in FIG.

The workpiece W2 that has been subjected to the diameter reduction process in this manner is a mechanical joint W3 as a finished product by forming a female screw 12a on the inner wall of the through hole 11 of the small diameter portion 12.
According to the rebar mechanical joint manufacturing apparatus and manufacturing method according to the present embodiment described above, since the press machine 2 and the mandrel 5 are configured as separate bodies, the work W1 is reduced in diameter and the work W1 and the core are separated. Even in a state where the gold 5 is crimped, the punch 32 can be separated from the workpiece W1. Therefore, unlike the case where the punch 32 and the mandrel 5 are integrated, when the punch 32 that has entered the die 42 is returned to the outside of the die 42, an unreasonable force is exerted on the punch 32 or the like by the pressure bonding of the workpiece W1 and the mandrel 5. It is possible to prevent the punch 32 and the like from being damaged.
Further, the mandrel 5 crimped to the workpiece W2 by the diameter reduction processing can be removed from the workpiece W2 by the knockout 46.

  Further, since the mandrel pin 54 is attached to the head 51 via the spring 53 and can be expanded and contracted in the axial direction, the workpiece W1 is expanded while being crimped to the mandrel pin 54 by diameter reduction processing. When doing so, the force acting on the mandrel pin 54 can be absorbed by the extension of the spring 53, and the mandrel 5 can be prevented from being damaged.

In the above-described embodiment, the length of the portion of the workpiece W1 to be reduced in diameter is appropriately determined by the length of the reduced diameter portion 422 of the die 42 or the amount by which the workpiece W1 is pushed into the forming hole 42a of the die 42 by the punch 32. It can be changed by setting to.
Further, the mandrel pin 54 is composed of three parts having different diameters, that is, a large diameter part 54a, a small diameter part 54b, and a tip part 54c. It is also possible to configure only the small diameter portion 54b that determines the diameter of the through hole 11.

W1 Work W2 Work W3 Mechanical joint 11 Through hole 12 Small diameter part 12a Female thread 13 Large diameter part 2 Press machine 3 Upper base 31 Punch plate 32 Punch 33 Punch holder 34 Punch fastening metal fitting 35 Plain guide 36 Knockout coupling joint 37 Knockout receiving metal fitting 38 Knockout adjusting screw 4 Lower base 41 Die plate 42 Die 43 Die holder 44 Die tightening bracket 45 Knockout guide flange 46 Knockout 5 Core 51 Head 52 Cap screw 53 Spring 54 Core 54 Pin

Claims (7)

By reducing the diameter of a cylindrical workpiece with a through hole formed inside, it has a through hole for inserting a rebar inside, and manufactures a mechanical joint of a rebar that is plastically processed radially inside. A device,
A press machine that performs plastic working on the workpiece, and a substantially bar-shaped mandrel that is inserted into the insertion hole of the workpiece,
The press machine
A punch for pressing the workpiece into which the mandrel is inserted;
A hole having a certain length into which the punch enters together with the workpiece, the inner diameter is substantially the same as the outer diameter of the workpiece, a large diameter portion formed on the punch side, and the inner diameter is A die having a smaller diameter than the outer diameter of the workpiece, and a molding hole including a small diameter portion formed on the side facing the punch across the large diameter portion;
A knockout that is disposed on the side facing the punch across the molding hole and interlocks with the punch and enters the molding hole.
The above core is
The outer diameter is smaller than the diameter of the through hole of the workpiece, the axial length is longer than the axial length of the through hole of the manufactured mechanical joint, and the workpiece penetrates. An end portion that is inserted into the insertion hole and extends from the insertion hole of the workpiece to the knockout side has a mandrel pin that receives a pressing force from the knockout,
An apparatus for manufacturing a mechanical joint for reinforcing steel bars. The mandrel further includes a head that receives a pressing force from a punch that is sandwiched between the workpiece and the punch and enters the die,
The mandrel pin is attached to the head via a spring that expands and contracts in the axial direction.
The apparatus for manufacturing a mechanical joint for reinforcing steel bars according to claim 1. The head is formed with a claw portion that is hooked to the edge of the insertion hole of the workpiece and positions the mandrel at a position where the axial center coincides with the center of the insertion hole.
An apparatus for manufacturing a mechanical joint for reinforcing steel bars according to claim 2. The manufactured mechanical joint of the reinforcing bar is formed with a female screw for screwing a bolt connecting a pair of mechanical joints, with a male screw formed on the outer peripheral surface thereof,
The diameter of the mandrel pin of the mandrel consists of the lower diameter of the female screw formed in the through hole,
The manufacturing apparatus of the mechanical coupling of the reinforcing bar according to any one of claims 1 to 3. The surface of the mandrel pin of the mandrel is coated with a wear-resistant material or subjected to a wear-resistant treatment,
The manufacturing apparatus of the mechanical coupling of the reinforcing bar according to any one of claims 1 to 4. The mandrel pin of the mandrel is formed with a taper whose diameter decreases toward the knockout side,
The apparatus for manufacturing a mechanical joint according to any one of claims 1 to 5. By reducing the diameter of a cylindrical workpiece with a through hole formed inside, it has a through hole for inserting a rebar inside, and manufactures a mechanical joint of a rebar that is plastically processed radially inside. A method,
A punch for pressing the workpiece into which the mandrel is inserted;
A hole having a certain length into which the punch enters together with the workpiece, the inner diameter is substantially the same as the outer diameter of the workpiece, a large diameter portion formed on the punch side, and the inner diameter is A die having a smaller diameter than the outer diameter of the workpiece, and a molding hole including a small diameter portion formed on the side facing the punch across the large diameter portion;
A press machine having a knockout that is disposed on the side facing the punch across the molding hole and interlocks with the punch and enters the molding hole;
The outer diameter is smaller than the diameter of the through hole of the workpiece, the axial length is longer than the axial length of the through hole of the manufactured mechanical joint, and the workpiece penetrates. With a mandrel having a mandrel pin inserted into the insertion hole and extending from the through hole of the workpiece to the knockout side, the mandrel pin receiving the pressing force from the knockout,
A step of pushing the workpiece into the die by the punch;
Pressing the mandrel pin of the mandrel protruding from the open end of the through hole of the workpiece by the knockout, and pushing out the mandrel from the through hole of the workpiece;
Performing the step of pushing the work pushed into the die out of the die by the knockout,
A method for manufacturing a mechanical joint for reinforcing steel bars.

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