JP2007090406A - Producing facility for round steel tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a producing facility for a round steel tube with which the round steel tube can easily and surely be produced without applying a refining work with a hand-work even if the tube has a large thickness and a large diameter. <P>SOLUTION: This producing facility for a round steel tube is used for performing welding-joint with a welding means after press-forming a steel plate 1 which has edges 2 at both ends in the width direction and has a prescribed width W, with a pressing means 10. The pressing means comprises: an outer die 15 where a recessed formed surface 16 having the radius R corresponding to the outer diameter of the round steel tube is formed so as to have a prescribed length; an inner die 17 where a projected formed surface 18 having the radius r corresponding to the inner diameter of the round steel tube is formed so as to have a prescribed length and which is freely moved so as to be approached/separated to the outer die; and roller bodies 20 set so as to be freely stopped/rotated at the outer parts of both sides of the outer die. The roller bodies are arranged so as to be freely approached/separated to the outer die and also, energized in the approaching direction with an energizing body 23, and are constituted so that a part of the outer peripheries 20a are projected to the inside from the extended surfaces 16a of the recessed formed surface, when the roller bodies are approached to the outer die. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a manufacturing equipment for a round steel pipe employed to obtain a large-diameter, thick-walled round steel pipe used for, for example, a building pillar.

Conventionally, this type of round steel pipe has been manufactured by the following method. That is, a pipe original plate having a predetermined width and a predetermined length is prepared, and end bending of a predetermined width is performed by pressing on an end portion in the width direction of the pipe original plate. Next, the substantially center portion of the end-bent pipe original plate is further pressed to be bent so that the cross-sectional shape is substantially U-shaped. And it shape | molds so that a cross-sectional shape may become a substantially circular shape by the press work means which consists of a pair of shaping | molding die which has a semicircle-shaped shaping | molding surface. At this time, the concave portion and the convex portion are engaged. There is also a method in which the cross-sectional shape is formed so as to be substantially circular, and then the end portions (joint portions) are welded and joined (see, for example, Patent Document 1).
JP-A-9-234511 (page 3-5, FIGS. 1 and 2)

  However, according to the above-described conventional method, the manufactured pipe has a substantially circular cross-section and hardly forms a perfect circle. To make a perfect circle, manual refining work must be performed for a long time. I must.

  For example, as a thick bending method, there is a method of forming a substantially circular shape by pressing a large number of locations in the width direction (for example, 40 to 50 locations when the diameter is 600 mm). In this case, the manufacturing time is increased by pressing at a large number of places, and in order to obtain a perfect circle, a manual refining operation must be performed for a long time.

  Accordingly, the invention according to claim 1 of the present invention is a manufacturing equipment for round steel pipes that can easily and reliably manufacture round steel pipes without performing manual refining work even if they are thick and large in diameter. Is intended to provide.

  In order to achieve the above-described object, the round steel pipe manufacturing facility according to claim 1 of the present invention is configured to press a steel plate having a predetermined width with grooves formed at both ends in the width direction using a press means, and then using a welding means. It is a production facility for round steel pipes that welds the gaps, and the pressing means corresponds to the outer mold that has a concave formed surface with a radius corresponding to the outer diameter of the round steel pipe, and the inner diameter of the round steel pipe A convex molding surface having a radius that has a predetermined length, and an inner mold that is movable toward and away from the outer mold, and a roller body that is disposed so as to be freely rotatable outward on both sides of the outer mold. Both roller bodies are arranged so as to be able to approach and separate from the outer mold, and are biased in the approaching direction by the biasing body, and when the roller body is brought closer to the outer mold, a part of the outer periphery is formed into a concave shape. It is characterized by being configured to protrude inward from the extended surface of the surface.

  Therefore, according to the first aspect of the present invention, the press-corresponding portion of the steel sheet is positioned between the outer mold and the inner mold while the inner mold is moved away from the outer mold. At this time, the two roller bodies are positioned at the outer mold side approach limit by the urging force of the urging body, and a part of the outer periphery protrudes inward from the extended surface of the concave forming surface to receive the steel plate. In this state, by moving the inner mold closer to the outer mold, the press-corresponding portion can be bent by the concave molding surface of the outer mold and the convex molding surface of the inner mold. At this time, since the radius of the concave molding surface corresponds to the outer diameter of the round steel pipe and the radius of the convex molding surface corresponds to the inner diameter of the round steel pipe, bending of the press equivalent part by press molding is round. The shape is equivalent to the outer diameter of the steel pipe, and is performed with a predetermined length.

  Furthermore, at the time of press molding, the vicinity of the press equivalent part is also pressed against the outer periphery of the roller body projecting inward from the extended surface of the concave molding surface, and the vicinity of this press equivalent part is bent, As a result, the desired press forming can be facilitated, and the press-equivalent partial bending can be performed smoothly and accurately. At that time, due to the pressing force applied to the roller body, the roller body is moved away from the urging force of the urging body, and the outer periphery thereof is positioned on the extended surface or outside of the concave molding surface. Therefore, the bending in the vicinity of the portion corresponding to the press can be suitably performed without difficulty.

  After performing the first press molding in this manner, the inner mold is moved away from the outer mold, and the steel plate is moved by a predetermined amount, so that the next press-corresponding portion connected to the molded portion is moved to the outer mold. Next, the inner die is moved closer to the outer die, and the portion corresponding to the next press of the steel plate can be bent in the same manner. Then, by repeating the same press forming, a round-shaped round steel pipe can be formed (tube making). After performing the desired press forming in this way, the round shaped steel pipe is taken out from the press means, loaded into the welding means, and welded between the grooves to produce a round steel pipe with a predetermined outer diameter. Can do.

  According to a second aspect of the present invention, there is provided a round steel pipe manufacturing facility according to the first aspect, wherein the outer mold has a predetermined length of the concave molding surface and the inner mold has a predetermined length of the convex molding surface. One press-forming length is one-multiple of the circumferential length of the round steel pipe, and is characterized by being formed into a round shape by a plurality of press-forming operations.

Therefore, according to the second aspect of the present invention, the bending of the steel sheet by press forming can be performed in a shape equivalent to the outer diameter of the round steel pipe and corresponding to a plurality of the peripheral length of the round steel pipe.
And the manufacturing equipment of the round steel pipe of Claim 3 of this invention WHEREIN: In the structure of above-mentioned Claim 1 or 2, the steel plate of the predetermined width which formed the groove | channel in the both ends of the width direction is heated with a heating means, The heated steel sheet is hot-press formed by a pressing means.

  Therefore, according to the invention of claim 3, after the steel sheet is heated entirely through the heating means, it can be bent into a round steel pipe by a plurality of hot press formings by the pressing means, and the round steel pipe is manufactured by welding joining. obtain.

  According to the first aspect of the present invention described above, the press-corresponding portion of the steel plate is positioned between the outer mold and the inner mold which are moved apart, and at this time, both roller bodies are moved to the outer mold side by the biasing force of the biasing bodies. In this state, a part of the outer periphery protrudes inward from the extended surface of the concave forming surface to receive the steel plate, and in this state, the outer die is moved closer to the outer die. The press-corresponding portion can be bent and formed by the concave molding surface of the mold and the convex molding surface of the inner mold. At this time, since the radius of the concave molding surface corresponds to the outer diameter of the round steel pipe and the radius of the convex molding surface corresponds to the inner diameter of the round steel pipe, bending of the press equivalent part by press molding is round. It can be performed in a shape equivalent to the outer diameter of the steel pipe and with a predetermined length.

  Furthermore, at the time of press molding, the vicinity of the press equivalent part is also pressed against the outer periphery of the roller body projecting inward from the extended surface of the concave molding surface, and the vicinity of this press equivalent part is bent, As a result, the desired press forming can be promoted, and the press equivalent partial bending can be smoothly and accurately performed. At that time, due to the pressing force applied to the roller body, the roller body is moved away from the urging force of the urging body, and the outer periphery thereof is positioned on the extended surface or outside of the concave molding surface. Therefore, the bending near the press-corresponding portion can be suitably performed without difficulty.

  After performing the first press molding in this manner, the inner mold is moved away from the outer mold, and the steel plate is moved by a predetermined amount, so that the next press-corresponding portion connected to the molded portion is moved to the outer mold. By positioning the inner die between the outer die and the inner die, the next press-corresponding portion of the steel sheet can be bent and formed in the same manner. Then, by repeating the same press forming, a round circular steel pipe can be formed (tube making). After performing the desired press forming in this way, the round shaped steel pipe is taken out from the press means, loaded into the welding means, and welded between the grooves to produce a round steel pipe with a predetermined outer diameter. it can.

  In this way, a round steel pipe can be manufactured by repeated press forming of a predetermined length, that is, by a small number of press forming and welding joints, so that even if the round steel pipe has a thick wall and a large diameter, It can be efficiently obtained in a short time without performing the refining work.

  According to the second aspect of the present invention described above, the bending of the steel sheet by press forming is performed in a shape equivalent to the outer diameter of the round steel pipe and corresponding to a plurality of the peripheral length of the round steel pipe. be able to.

  According to the third aspect of the present invention described above, after the steel sheet is entirely heated through the heating means, it can be formed into a round steel pipe by hot press forming a plurality of times by the pressing means, and the round steel pipe is formed by welding. Can be manufactured. In this case, a homogeneous round steel pipe having no residual stress and sufficient toughness can be produced by hot press forming.

[Embodiment 1]
Below, Embodiment 1 of this invention is demonstrated based on FIGS.
As shown in FIGS. 12 and 13, the manufacturing equipment for the round steel pipe has a transport path 7 for transporting a steel plate 1 having a predetermined width W, a predetermined thickness T, and a predetermined length L corresponding to the round steel pipe in the length direction. Inside, a trimming groove processing machine 8 for forming the welding groove 2 at both end portions in the width direction of the steel plate 1, heating means 9 for heating the steel plate 1 on which the groove 2 is formed, and the heated steel plate The press means 10 for hot press forming 1 and the welding means 30 for welding and joining between the grooves 2 after hot press forming are arranged in order from upper to lower.

  As shown in FIG. 1, the pressing means 10 has a holding body 12 that is fitted and fixed to the main body 11, and a detachable recess 13 is formed in the central portion of the upper surface of the holding body 12. Roller body guide portions 14 are formed on the left and right sides of the detachable recess 13. Here, the roller body guide portion 14 has a horizontal guide surface 14a positioned between the holding body upper surface 12a and the bottom surface 13a of the detachable recess 13 in the vertical direction, and is continuous with the outer ends of these guide surfaces 14a. Thus, the stopper surface 14b is formed as an upward arcuate shape.

  An outer mold (lower mold) 15 is detachably fitted into the detachable recess 13, and the upper surface of the outer mold 15 has a radius corresponding to the outer diameter Φ of the round steel pipe 5 (see FIG. 11) as the final product. A concave molding surface 16 of R is formed upward with a predetermined length. An inner mold (upper mold) 17 is provided above the outer mold 15, and the lower surface of the inner mold 17 has a convex molding surface 18 having a radius r corresponding to the inner diameter Φs of the round steel pipe 5 with a predetermined length. It is formed downward. Here, the inner mold 17 is connected to the lower end of an elevating body 19 detachably attached to an elevating device (not shown), and is configured to be movable toward and away from the outer mold 15. Thereby, press molding is enabled by the concave molding surface 16 of the outer mold 15 and the convex molding surface 18 of the inner mold 17. At this time, the concave molding surface 16 having a predetermined length and the convex molding surface 18 having a predetermined length are provided. The one-time press forming length PL is set to approximately 1/7 (a plurality of ones) of the circumferential length of the round steel pipe 5.

  Roller bodies 20 are disposed on both sides of the outer die 15, and the roller bodies 20 are configured to be freely rotatable with respect to the roller shaft 21. Both roller bodies 20 are mounted on the guide surface 14a, and are configured to be able to approach and separate from the outer mold 15 by free rotation. The two roller bodies 20 are provided with a compression spring (an example of an urging body) 23 between the receiving member 22 provided on the left and right outer ends of the holding body 12 and the roller shaft 21 side. Is being energized. At that time, the approach limit is restricted by contacting the left and right side surfaces of the outer mold 15, and the separation limit is regulated by contacting the stopper surface 14b. Further, when the roller body 20 is brought close to the outer mold 15, that is, when the roller body 20 is close to the right and left side surfaces of the outer mold 15, a part of the outer periphery 20 a is inside the extended surface 16 A of the concave molding surface 16. It is configured to protrude (upward). An example of the press means 10 is configured by the above 11-23 and the like.

  As shown in FIGS. 10 and 13, the welding means 30 includes an upper temporary welding portion 31 and a lower main welding portion 32. Here, the tack welded portion 31 and the main welded portion 32 constrain the round steel pipe 3 from the outer periphery by three rows (a plurality of rows) of outer rolls 33 in the lower and right and left sides, and the groove (free end) 2 thereof. The welding machine 34 is configured to perform tack welding or main welding in a state where the two are substantially in contact with each other. At that time, the outer roll 33 group is a drum shape, and the concave arcuate surface 33 a is formed so as to correspond to the outer peripheral surface of the round steel pipe 5 described above.

Hereinafter, the operation in the first embodiment will be described.
First, as shown in FIG. 12A, a steel plate 1 having a width (an example of a predetermined width) W corresponding to a round steel pipe, a predetermined plate thickness T, and a predetermined length L is prepared. And as shown in FIG. 13, while conveying this steel plate 1 on the conveyance path | route 7, it passes through the trimming groove processing machine 8, and as shown in FIG.12 (b), the groove | channel 2 is shown in the both ends in the width direction. Process. Then the steel sheet 1, for example through a heating means 9 consisting of a combustion heating type of placed in a heating furnace, the whole heated to near (front and back) of the A ₃ transformation point, which is an example of a predetermined temperature (e.g. 850 to 1,050 ° C.) To do. Then, the heated steel plate 1 is conveyed in the length direction and supplied to the press means 10, and the round steel pipe 3 is bent and formed by seven (multiple) hot press forming by the press means 10.

  That is, as shown in FIG. 1, the steel plate 1 is set from the holding body upper surface 12a to the outer periphery 20a of one roller body 20 with the inner mold 17 moved away from the outer mold 15 by ascending. One end portion (a portion corresponding to the press) of the steel plate 1 is positioned between the outer die 15 and the inner die 17. At this time, the two roller bodies 20 are positioned in the approach limit contacting the left and right side surfaces of the outer mold 15 by the urging force of the compression spring 23, and a part of the outer periphery 20 a is more than the extended surface 16 A of the concave molding surface 16. It protrudes inward.

  After positioning one end of the steel plate 1 between the outer mold 15 and the inner mold 17 in this way, the inner mold 17 is moved closer to the outer mold 15 by descending, as shown in FIG. The steel sheet 1 can be bent by the concave molding surface 16 of the outer mold 15 and the convex molding surface 18 of the inner mold 17. That is, one end of the steel plate 1 can be bent (end bent) by the first hot press forming by the pressing means 10. At this time, the radius R of the concave shaped surface 16 corresponds to the outer diameter Φ of the round steel pipe 5 and the radius r of the convex shaped surface 18 corresponds to the inner diameter Φs of the round steel pipe 5. The bending of the one end portion of the steel plate 1 by the intermediate press forming is performed in a shape equivalent to the outer diameter Φ (diameter) of the round steel pipe 5 and corresponding to approximately 1/7 of the circumferential length of the round steel pipe 5. Is called.

  Further, at the time of hot press forming, a part of the outer periphery 20a of one roller body 20 protrudes inward from the extended surface 16A of the concave forming surface 16, so that the roller body 20 also has a portion near one end of the steel plate 1. It will be in pressure contact, and it will be in the state which bends the vicinity of one end part, and this facilitates the 1st hot press molding by the outer mold | type 15 and the inner mold | type 17, and makes the bending formation of one end part smooth. And it can be done accurately. At this time, the roller body 20 is moved away from the urging force of the compression spring 23 by the pressing force applied to the roller body 20, and the outer periphery 20a is positioned on the extended surface 16A of the concave molding surface 16 or on the outside. Therefore, the bending near the one end can be carried out suitably without difficulty.

  After performing the first hot press forming in this manner, the inner die 17 is moved away from the outer die 15 and the steel plate 1 is moved to the other side by a predetermined amount, as shown in FIG. In addition, the next press-corresponding portion (continuous) connected to the formed one end can be set between the outer die 15 and the inner die 17. Next, the inner mold 17 is moved closer to the outer mold 15, and as shown in FIG. 4, the second hot press molding by the pressing means 10 performs the concave molding of the outer mold 15 in the same manner as the first. The steel plate 1 can be bent by the surface 16 and the convex forming surface 18 of the inner mold 17. At this time, the steel plates 1 are in pressure contact with both roller bodies 20 and act in the same manner as described above. And by repeating the same, as shown in FIG. 5, the next press equivalent portion of the steel sheet 1 can be bent and formed by the third hot press forming by the pressing means 10.

  In this way, after performing hot press forming three times on the one end side, the steel plate 1 is largely moved to the other side, and the other end is set between the outer mold 15 and the inner mold 17. Thereby, as shown in FIG. 6, the other end part of the steel plate 1 can be bent and formed by the fourth hot press forming. Then, the fifth hot press forming shown in FIG. 7 and the sixth hot press forming shown in FIG. 8 are performed in the same manner, so that the steel sheet 1 is rounded with the central portion in the length direction remaining. It can be hot formed to approximate shape.

  Next, as shown in FIG. 9, the seventh round hot-press molding is performed in the same manner on the remaining central portion, whereby the round-shaped round steel pipe 3 can be molded (pipemaking). At this time, the end surface on the side of the groove 2 is brought into contact with both side surfaces of the lifting and lowering body 19, so that the round steel pipe 3 moves up and down with respect to a perfect circle corresponding to the outer diameter Φ of the round steel pipe as the final product. It becomes a form deformed against its own elasticity by the thickness of the body 19.

  After performing the hot press forming seven times (all) in this way, the inner die 17 is moved away from the outer die 15, and the round steel pipe 3 is extracted in the direction of the tube axis, thereby pressing means. The round steel pipe 3 can be taken out from 10. At that time, the extraction is performed while the end surfaces on the side of the groove 2 are brought into sliding contact with both side surfaces of the lifting body 19. And the round-shaped steel pipe 3 taken out from the press means 10 turns into the round-shaped steel pipe 3 which made the end surfaces by the side of the groove | channel 2 correspond considerably by own elastic restoring force.

  In this way, the round steel pipe 3 taken out from the press means 10 is carried into the welding means 30, and the end faces (free ends) on the groove 2 side are connected to each other while restraining the round steel pipe 3 from the outer periphery ( Welding is performed in the state of facing each other. That is, as shown in FIG. 10, in the tack welded portion 31, the round steel pipe 3 is constrained from the outer periphery by the outer roll 33 group, and the gaps 2 are spaced between the grooves 2 by the welding machine 34 in a state in which the end faces are substantially in contact with each other. Tack welding 4A is performed. Next, in the main welding portion 32, the round steel pipe 3 is constrained from the outer periphery by the outer roll 33 group, and the welding connection 4 is performed by the welding machine 34. In this way, by performing the welding joint 4 using the groove 2, as shown in FIG. 11, a round steel pipe (final product) 5 having a predetermined outer diameter Φ and a length L is manufactured (pipemaking). obtain.

  At that time, the round steel pipe 5 can be manufactured by seven hot press moldings based on one press molding length PL, that is, by a small number of (multiple) hot press moldings and welding joints 4, Therefore, even if the round steel pipe 5 is thick and has a large diameter, the round steel pipe 5 can be obtained efficiently and inexpensively without performing manual refining work. Moreover, the homogeneous round steel pipe 5 which does not have a residual stress and has sufficient toughness by hot press molding can be manufactured.

As described above, for example, a round steel pipe 5 having a thickness of 25 to 120 mm, a diameter of 1200 mm or more, and a length of 7000 mm or more, that is, a large diameter and extremely thick round steel pipe 5 can be preferably manufactured. In addition, the round steel pipe 5 taken out from the place of the welding means 30 is conveyed to a correction device, a front end cutting device, a rear end cutting device, a cleaning device, a rust prevention device, etc. (not shown) as necessary. After being processed, it is stored as a product.
[Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIG.

  That is, the idle roller 25 having a predetermined length in the vertical direction is provided at a predetermined position of the elevating body 19. Here, the idle roller 25 has a length direction in which the idle roller 25 on one side that slightly protrudes from one side of the lifting body 19 and the idle roller 25 on the other side that slightly protrudes from the other side are in the length direction. A plurality are alternately arranged in the (tube axis direction).

  Therefore, when the last hot press molding is performed on the remaining central portion to form a round-shaped round steel pipe 3, the end surface on the groove 2 side contacts the outer peripheral surface of the idle roller 25 group. Is done. Thereby, when the round steel pipe 3 is extracted in the axial direction of the pipe and taken out from the press means 10, the idle roller 25 group is caused to idle by the end face on the groove 2 side. It can be done smoothly with less.

In the above-described embodiment, when the upper surface of the main body 11 is formed by the idle roller group, the steel plate 1 can be moved more smoothly in the width direction.
In the above-described embodiment, when manufacturing the round steel pipe 5 having a different outer diameter Φ, the outer mold 15 having a different radius R of the concave molding surface 16 is fitted into the holding body 12, and the lifting device is What is necessary is just to attach the inner mold | type 17 from which the radius r of the convex-shaped surface 18 differs. Moreover, what is necessary is just to attach the internal type | mold 17 from which the radius r of the convex-shaped shaping | molding surface 18 differs with respect to the change of plate | board thickness T with respect to a raising / lowering apparatus.

  In the above-described embodiment, the round steel pipe 3 is formed by performing the press molding seven times. This is a predetermined length of the concave molding surface 16 and the convex molding surface 18, that is, one press molding. Depending on the length PL, it is possible to perform press forming a small number of times by press forming 6 times or less or 9 times or more.

In the above-described embodiment, a form in which the compression spring 23 is employed as the urging body is shown, but this may be in a form in which a urging method utilizing hydraulic pressure is employed.
In the above-described embodiment, a form in which a concave arcuate surface 33 a corresponding to the outer diameter Φ of the round steel pipe 5 is formed as the outer roll 33 of the welding means 30 is shown. This is the outer diameter of the round steel pipe 5. The outer roll forming the concave arc-shaped surface corresponding to the change of Φ can be arbitrarily replaced and disposed.

  In the above-described embodiment, the approach limit of the two roller bodies 20 is regulated by contacting the left and right side surfaces of the outer mold 15, but this is achieved by bringing the roller shaft 21 into contact with a separately provided stopper body. It may be regulated.

  In the above-described embodiment, a form in which the steel plate 1 heated through the heating means 9 is hot press formed by the pressing means 10 is shown. This is because the unheated steel sheet 1 is cooled by the pressing means 10. It may be in the form of intermediate press molding. In this case, it is particularly suitable for manufacturing a round steel pipe having a thin plate thickness T.

BRIEF DESCRIPTION OF THE DRAWINGS It is Embodiment 1 of this invention, and is a front view before the press molding of the one end part in the manufacturing equipment of a round steel pipe. It is a front view at the time of the press molding of the one end part in the manufacturing equipment of the same round steel pipe. It is a front view before the 2nd press molding in the manufacturing equipment of the same round steel pipe. It is a front view at the time of the 2nd press molding in the manufacturing equipment of the same round steel pipe. It is a front view at the time of the 3rd press molding in the manufacturing equipment of the same round steel pipe. It is a front view at the time of the 4th press molding in the manufacturing equipment of the same round steel pipe. It is a front view at the time of the 5th press molding in the manufacturing equipment of the same round steel pipe. It is a front view at the time of the 6th press molding in the manufacturing equipment of the same round steel pipe. It is a front view at the time of the 7th press molding in the manufacturing equipment of the same round steel pipe. It is a front view of the welding means part in the manufacturing equipment of the same round steel pipe. It is a front view of the round steel pipe manufactured with the manufacturing equipment of the same round steel pipe. The steel plate in the manufacturing equipment of the said round steel pipe is shown, (a) is a perspective view of the steel plate used, (b) is a partially notched front view of the steel plate in which the groove | channel was formed. It is a schematic explanatory drawing of the process in the manufacturing equipment of the same round steel pipe. It is Embodiment 2 of this invention, and is a front view at the time of the 7th press molding in the manufacturing equipment of a round steel pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Groove 3 Round-shaped steel pipe 4 Welded joint 5 Round steel pipe 7 Conveyance path 8 Trimming groove processing machine 9 Heating means 10 Press means 11 Main body 12 Holding body 14 Roller body guide part 15 Outer die 16 Concave-shaped surface 16A Extension surface 17 Inner mold 18 Convex forming surface 19 Lifting body 20 Roller body 20a Outer periphery 21 Roller shaft 22 Receiving member 23 Compression spring (biasing body)
25 Rolling roller 30 Welding means 31 Tack welded portion 32 Main welded portion W Predetermined width T Plate thickness L Predetermined length Φ Outer diameter of round steel pipe Φs Inner diameter R of round steel pipe Radius r of concave shaped surface 16 Convex shaped surface 18 Radius PL One press forming length

Claims (3)

  This is a round steel pipe manufacturing facility in which a steel plate having a predetermined width formed at both ends in the width direction is press-formed by a press means, and the gaps are welded to each other by a welding means. An outer mold in which a concave molding surface having a radius corresponding to the diameter is formed to a predetermined length, and a convex molding surface having a radius corresponding to the inner diameter of the round steel pipe is formed in a predetermined length and moved toward and away from the outer mold. A free inner mold and a roller body that is arranged so as to be free to rotate outward on both sides of the outer mold. An apparatus for manufacturing a round steel pipe, characterized in that when the roller body is urged in the approaching direction and a roller body is brought close to the outer mold, a part of the outer periphery protrudes inward from the extended surface of the concave molding surface.   One press molding length by the concave molding surface having a predetermined length of the outer die and the convex molding surface having a predetermined length of the inner die is a plurality of times of the circumferential length of the round steel pipe, 2. The equipment for manufacturing a round steel pipe according to claim 1, wherein the equipment is formed into a round shape by press molding. 3. A round steel pipe according to claim 1, wherein a steel plate having a predetermined width formed with grooves at both ends in the width direction is heated by a heating means, and the heated steel plate is hot press formed by a pressing means. Facility.

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