Title of Invention

CONSTRUCTION METHOD OF STEEL PIPE

Abstract

The construction method of a steel pipe P is disclosed. The construction method of a steel pipe P is capable of achieving an easier construction of a steel pipe P and minimizing the construction period thereby in such a manner that neighboring steel pipes P are roughly arranged at a construction site, and ends of the neighboring steel pipes P are held using a shaper (10) are externally pressurized in a radial direction for thereby achieving a perfect circle shape, and then the steel pipes P are arranged in a straight line shape, and the ends of the steel pipes are arranged to abut with each other or are inserted each other, so that the conjunction portions of the inner or outer surface of the steel pipe are welded.

Full Text

Technical Field The present invention relates to a construction method of a steel pipe having a diameter of over 600mm, and in particular to a construction method of a steel pipe in which neighboring steel pipes are roughly arranged, and a shaper is installed at the ends of the steel pipes for thereby forming a perfect circle, and the ends of the perfect circles are arranged to abut with each other or are inserted into each other, so that abutting portions of inner or outer surfaces are welded. Background Art Generally, a steel pipe has been used for a line pipe, an oil pipeline, a water pipe, etc. and has a diameter of over 600mm. In the fabrication method of the steel pipe, there are a roll bending method and a spiral method. In the roll bending method, a steel pipe is bent with a circular cross section using a plurality of rolls, and the abutting ends of the steel pipes are welded in the direction of a centerline. In the spiral method, the steel pipe is wound in a spiral shape using a belt steel and is welded, while twisting the same. The spiral method in the fabrication method of the steel pipe has a thin plate material, and a mass production is made easier. However, in the case that the steel pipe is thick, accuracy is decreased during the fabrication. Therefore, the roll bending method has been generally used. Even when the steel pipes are fabricated based on the roll bending method, it is very difficult to achieve a perfect circle steel pipe due to its fabrication method, so that a non-perfect circle steel pipe is fabricated. The allowable error has a range of 0. 5% of a circular surrounding length based on the KS standard. As the diameter of the steel pipe gets increased, the error gets increased. For example, in the case of the steel pipe of 600mm, the error is permitted within a range of 597mm-603mm, so that at least 6mm error occurs. The error is more increased at the upper portion of the steel pipe due to the accumulating error in addition to the above error, so that there are many problems in the abutting method and the constriction based on a socket connection. The above problems occur due to the following reasons. Namely, when the steel pipes are constructed using a socket joint type at the construction site of the steel pipes, it is needed to insert the other end of the neighboring steel pipe into the socket of one end of the steel pipe, so that it is impossible to achieve a proper insertion because of the deformed cross section shape of the steel pipe. In the conventional insertion method of the steel pipe, a certain wedge is inserted into the portion that is not inserted due to the deformed shape to have a certain perfect circle in a state that the other end of the neighboring steel pipe is suspended at the socket of an end of the steel pipe and is stroke. In another method, a turnbuckle or a chain block is inserted at an inner surface of the steel pipe for thereby performing an insertion process. Since the above steel pipe is inserted under the ground, the ground is excavated along the line in which the steel pipe is buried. The insertion construction of the steel pipe is performed in a state that the steel pipes are roughly arranged at the excavated portions. Therefore, in this case, the work gets bad, and the construction period may be delayed, and safety accidents may occur. In particular, it is needed to excavate the ground deeper and wider at the portions of abutting both ends of the neighboring steel pipes. Since the workers have to work the insertion construction of the steel pipe at the above portions, the construction period is delayed and extended, and safety accidents may occur. Disclosure of Invention Accordingly the present invention provides a construction method of a steel pipe, comprising: a) aligning the steel pipes in such a way to get neighboring steel pipes (P) closer in a straight line shape at a construction site in which steel pipes are constructed; b) installing a shaper (10)which is at an outer surface of the end of each aligned steel pipe P obtained from step (a) , wherein the ends of the said steel pipes (P) are pressurized by the shaper (10) in a radial direction towards the direction of the center, thereby adjusting and maintaining the perfect circle shape; c) abutting the end circumferential surfaces of the steel pipes (P) of step (b) inserting into a socket (PS) in such a manner that the steel pipes P are maintained in a straight line shape; and d) welding the conjunction portions of the inner or outer surface of the neighboring steel pipes P obtained from step (c ) . Accordingly, it is an object of the present invention to overcome the above-described problems. It is another object of the present invention to provide a construction method of a steel pipe capable of achieving an easier construction of a steel pipe and minimizing the construction period thereby in such a manner that neighboring steel pipes are roughly arranged at a construction site, and ends of the neighboring steel pipes are held using a shaper are externally pressurized in a radial direction for thereby achieving a perfect circle shape, and then the steel pipes are arranged in a' straight line shape, and the ends of the steel pipes are arranged to abut with each other or are inserted each, ether, so that the conjunction portions of the inner or outer surface of the steel pipe are welded. It is further another object of the present invention to provide a construction method of a steel pipe capable of preventing a safety accident which may occur during a perfect circle shaping work or a welding work at the ends of the steel pipes in such a manner that a plurality of hydraulic cylinders are provided at a shaper in a radial shape, and a welding robot is prepared at a conjunction portion of an inner or otter surface of the steel pipe. To achieve the above objects, there is provided a construction method of a steel pipe, comprising an aligning step in which steel pipes are arranged so that neighboring steel pipes P get most closer and are arranged in a straight line shape.- at a construction site in which steel pipes are constructed; a perfect circle formation step in which a shaper 10 is installed at an outer surface of an end of each steel pipe P aligned in the aligning step, and the ends of the steel pipes P aue pressurized using the shaper 10 in a radial direction in the direction of the center for thereby adjusting and maintaining the perfect circle shape; a matching step in which the end circumferential surfaces of the steel pipes P are abutted and inserted into a socket PS in a state that the stetel pipes P are maintained in a straight line shape after the perfect circle formation step; and a welding step in which the conjunction portions of the inner or outer surface of the neighboring steel pipes P matched by the matching step are welded. In the perfect circle forming step, the pressurizing is performed selectively and uniformly in the direction from the inner side to the outer side of the steel pipe not in the direction opposed to the above pressurizing direction, namely, not in the direction from the outer side to the center of the steel pipe for thereby achieving a perfect circle. In another embodiment of the present invention, the perfect circle may be achieved by a method of concurrently pressurizing from the outer and inner sides of the steel pipes wherein the pressurizing is performed in the direction of the center at one side, and the pressurizing is performed in the direction from the center of the steel pipes to the outer side at the other side. The pulling unit of the matching step may be integral with the shaper and may be provided at the outer surface of the ends of the steel pipes separately from the above shaper and may be formed of a hydraulic cylinder or a turn buckle of which both ends are integrally connected with the shaper. The conjunction portions of the inner surface of the steel pipes are welded using a welding robot or a track-moving welding robot capable of welding wherein only welding device is rotated in a staue that it is moved along the longitudinal (center) direction in the interior of the steel pipes and is rotated in a stopped state. The conjunction portions of the outer surface of the steel pipes can be welded using a welding robot separately provided at an outer surface of the end of the steel pipes and a welding robot provided at the shaper installed for shaping the ends of the steel pipes. Brief Description of Drawings The preferred embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 is a schematic view illustrating a back hoe and a state that a shaper is installed at an arm for a back hoe for thereby achieving a construction method of a steel pipe according to the present invention; Figure 2 is affront view illustrating parts of a shaper of Figure 1; Figure 3 is a side view of Figure 2; Figure 4 is a perspective view illustrating a welding robot for a conjunction part of an inner surface of a steel pipe according to the present invention; Figure 5 is a view of a construction method of a steel pipe according to the present invention; and Figures 6 through 11 are views illustrating each process in a construction method of a steel pipe according to the present invention. Best Mode for Carrying Out the Invention The equipment for performing a construction method of a steel pipe according to the present invention will be described. Figure 1 is a schematic view illustrating a back hoe and a state that a shaper is installed at an arm for a back hoe for thereby achieving a construction method of a steel pipe according to the present invention, Figure 2 is a front view illustrating parts of a shaper of Figure 1, Figure 3 is a side view of Figure 2, and Figure 4 is a perspective view illustrating a welding robot for a conjunction part of an inner surface of a steel pipe according to the present invention. As shown therein, a shaper 10 is installed at an end of a work arm R of a back hoe (BH) and is capable of forming a perfect circle at an end of a steel pipe P that may be deformed while a steel pipe P is fabricated or is transferred to a construction site or is unloaded. The shaper 10 is installed at each end of the steel pipe P and is paired for thereby forming one unit. A pair of the shapers 10 are designed to be widened or contracted about the center of the steel pipe P and are connected and form one unit by a pulling unit 20. The shaper 10 is rotated about an axis 13 of one side of the semicircular bodies 11 and 12 and is opened and closed. The semicircular bodies 11 and 12 are opened and closed by an opening and closing cylinder 14. There is provided a locking apparatus 15 in order to prevent the bodies 11 and 12 from being widened when it is formed in a circular shape because the ends of the semicircular bodies 11 and 12 are abutted. A plurality of pressurizing cylinders 16 are provided in a radial shape at the semicircular bodies 11 and 12 in order to concurrently or individually pressurize the same in the direction of the center. The pulling unit 2 0 is provided in a form of a unit together with a pair of the shapers 10 installed at the ends of the neighboring steel pipes P. In this case, the pulling unit 20 may be formed of a hydraulic pulling cylinder. The pulling cylinders are installed at the regular angle at the semicircular bodies 11 and 12 for thereby achieving a concurrent pulling operation in order to pull the steel pipes without inclination in one side. In the above descriptions, the pulling unit 20 is provided in' the form of the unit together with the shapers 10. In another embodiment of the present invention, the pulling unit 2 0 may be provided in a type of turnbuckle or chain block at the inner or outer surface of the neighboring steel pipes P. In addition, the welding device is adapted to weld the conjunction portions of the inner or outer surface of the steel pipe P. In the present invention, the welding device may be provided in various types, but welding robots 3 0a and 3 0b may be preferably adapted in consideration of work efficiency and safety. In particular, the conjunction portions of the inner surfaces of the steel pipes P are preferably welded using the welding robot in order to prevent a suffocation accident or electric shock accident in the closed inner spaces of the steel pipes P. The welding robot 30a adapted to weld the conjunction portions of the inner surface of the steel pipe is preferably installed in the interior of the steel pipe P. As shown in Figure 4, the welding robot 3 0a includes a driving unit for moving along a longitudinal direction of the steel pipe P and a setting unit: capable of setting or fixing the same. In particular, there are further provided an arm 37 horizontally or vertically adjustable at a rotary shaft 3 6 rotating at a regular speed, and a welding unit 31 at an end of the arm 37. The welding robot 30b adapted to weld the conjunction portions of the outer surface of the steel pipe P is installed at the shaper "10 installed for shaping the perfect circle of y the end portions of the steel pipes P. The welding robot 3 0b is. integral with a semicircular guide rail 32 at one side of the semicircular body 11 of the shaper 10, and a welding device 33 is installed at the guide rail 32 for thereby performing a welding operation, moving by the driving source of a trolley 34. In the welding robot 30b, the semicircular i body 11 of the shaper 10 of one side includes a guide rail 32. The welding device 33 performs a welding work, moving along the guide rail 32. In the above descriptions, the operation that the welding device 33 moves along the guide rail 32 was described. In another embodiment of the present invention, a carriage having a small driving error with a self-driven unit may be preferably adapted. In addition, in the above description of the present invention, the welding robot 30b is installed at the shaper 10 of the outer surface of the steel pipe P, but a certain welding robot may be installed at an end of the outer surface of the steel pipe P. The construction method of the steel pipe according to the present invention will be described based on the above-described construction of the equipment. 1) Arranging process An excavating work is performed along a line in which steep pipes P are buried using an excavator or a back hoe (BH) that is heavy equipment. A clamp is engaged at a crane that is adapted to perform an excavating work and at an end of a work arm R of the excavator or back hoe, respectively. The steel pipe P is caught by the clamp and is placed down. As shown in Figure 6A, the steel pipes are arranged. When arranging the steel pipes P, the ends of the steel pipes P are arranged to meet each other in consideration of easier installation work of a shaper that is followed. At this time, in the excavating work, since the lengths of the steel pipes P are 6m 9m and 12m fabricated based on the roll bending method or spiral method, the excavated portions corresponding to the ends of the steel pipes P are formed deeper and wider based on the lengths of the steel pipes P because a shaper 10 is installed at the end portions of the steel pipes, and a welding device is installed for the conjunction portions of the outer surface of the steel pipe P. 2) Perfect circle formation process As shown in Figures 7 and 8, the shaper 10 is installed at the ends of the steel pipes P that are arranged in the aligning process, and the steel pipes P are pressurized in the radial direction from the inner and outer sides of the steel pipes P using the shaper 10 for thereby achieving a perfect circle shape and maintaining the same. In the process of installing the shaper 10 at the ends of the steel pipes P, the shaper 10 is engaged at the end of the work arm R of the back hoe, and then in a state that a locking device 15 of the shaper 10 is unlocked, the opening and closing cylinder 14 is operated, so that the semicircular bodies 11 and 12 are widened about the axis 13. At this time, the work arm R of the back hoe is moved and positioned at the semicircular bodies 11 and 12 of the shaper 10 for thereby holding the ends of the steel pipes P. In this state, two semicircular bodies 11 and 12 are contracted to form one circle by operating the opening and closing cylinders 14 and are locked using the locking device 15, and a plurality of pressurizing cylinders 16 installed at the semicircular bodies 11 and 12 in a radial shape are operated. All or part of the pressurizing cylinders 16 can be selectively operated. When selectively operating the pressurizing cylinders 16, the protruded portion is pressurized by operating only the pressurizing cylinder 16 positioned at the portion more outwardly protruded rather than an imaginary perfect circle for thereby achieving a perfect circle. The ends of the neighboring steel pipes P are deformed to have a certain perfect circle using the shaper 10 and are fixed. In the above descriptions, the operation that the pressurizing is performed in the direction from-the outer side of the steel pipe P to the center when shaping the ends of the steep pipes P to have a certain perfect circle, but the pressurizing may be performed in the radial direction from the inner side of the steel pipes P to the outer side. In addition, the pressurizing is performed in the direction of the center of the steel pipes P at the outer and inner sides of the steel pipes P, and concurrently the pressurizing is performed in the direction from the center of the steel pipes P to the outer side. 3) Matching process After the steel pipes are deformed to form a perfect circle in the perfect circle formation process, the steel pipes P are preferably matched in the horizontal state. As shown in Figure 9, the steel pipes P are pulled using the pulling unit so that the ends of the neighboring steel pipes P are inserted into the ends of the steel pipes P. The above operation will be described in detail. The pulling unit 20 installed at the shaper 10 of the ends of the steel pipes P is operated so that one side steel pipe P among the neighboring steel pipes P is pulled. At this time, the ends of the neighboring steel pipes P are relatively pulled and inserted into the socket PS of the steel pipe P. In the above operation, the ends of the steel pipes P are deformed to have a certain perfect circle by the shaper 10 for thereby achieving a smooth and easier insertion. 4) Welding process After the ends of the neighboring steel pipes P are inserted and engaged in the above matching step, as shown in Figures 10 and 11, the conjunction portions of the inner or outer surface of the steel pipes P are welded and rust-prevented and sealed. In the process of welding the conjunction portions of the inner surface of the steel pipes P, as shown in Figure 10, the welding robot 30a installed in the interior of the steel pipes P is positioned near the conjunction portions of the inner surface of the steel pipes P and is fixed, and the arm 3 7 of the welding robot 30a is adjusted in the horizontal and vertical states. The welding unit 31 is set to rotate along the conjunction portions of the inner surface of the steel pipes P, and the welding unit 31 is rotated using the rotary shaft 36 for thereby welding the conjunction portions of the inner surface of the steel pipes P. After the welding process is completed in the above manner, the set state of the welding robot 3 0a is released, and the welding robot 3 0a is moved in the longitudinal (centerline) direction of the steel pipes P and is fixed at a certain portion. In the process of welding the conjunction portions of the outer surface of the steel pipes P, the welding robot 30b installed at the semicircular body 11 of the shaper 10 installed at the outer surface of the steel pipe P, namely, the welding device 33 installed at the trolley 34 of the guide rail 32 is moved along the guide rail 32 in the direction from the lower side to the upper side of the conjunction portions of the outer surface of the steel pipes P, welding the conjunction portions of the outer surface of the steel pipes P. When welding the conjunction portions of the outer surface of the steel pipes P, if there is a certain concern about the limitation of the welding work due to the shaper 10, the shape 10 is disassembled and moved in the direction of the steel pipes P inserted into the socket PS of the steel pipes P or the end portion of the other steel pipe P, and then the welding ia performed using the welding device 33 of the welding robot 30b. As indicated by the arrow of Figure 11, the welding operation performed in the direction from the lower side to the upper side of the steel pipe P is performed more than two times for thereby finishing the welding work. In the above descriptions of the present invention, the method of inserting using the steel pipes P having the socket PS at ore end of the same was described. In another embodiment of the present invention, the abut joint method in which the outer ends of the neighboring steel pipes P are abutted and welded may be performed. Industrial Applicability A described above, in the construction method of the steel pipes according to the present invention, the excavating work is performed at the construction site, and the neighboring steel pipes are roughly arranged, and the ends of the neighboring steel pipes are held and pressurized in the radial shape in the inner and outer directions for thereby forming and fixing a perfect circle state. Thereafter, the ends of the neighboring steel pipes are horizontally arranged, and the ends of the steel pipes maintain abutted and inserted for thereby welding the conjunction portions of the inner surface or outer surface of the steel pipes, so that it is possible to achieve an easier construction of the steel pipes and to minimize the construction period of the steel pipes. In the present invention, a plurality of hydraulic are provided at the semicircular body of the shaper in a radial shape, and a welding robot capable of welding the conjunction portions of the inner surface of the steel pipes P is provided, so that it is possible to, prevent a safety accident that may occur during a perfect circle shaping work of the ends of the steel pipes or the welding work. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described examples are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims. WE CLAIM: l.A construction method of a steel pipe, comprising: a) aligning the steel pipes in such a way to get neighboring steel pipes (P) closer in a straight line shape at a construction site in which steel pipes are constructed; b) installing a shaper (10)which is at an outer surface of the end of each aligned steel pipe P obtained from step (a) , wherein the ends of the said steel pipes (P) are pressurized by the shaper (10) in a radial direction towards the direction of the center, thereby adjusting and maintaining the perfect circle shape; c) abutting the end circumferential surfaces of the steel pipes (P) of step (b) inserting into a socket (PS) in such a manner that the steel pipes (P) are maintained in a straight line shape; and d) welding the conjunction portions of the inner or outer surface of the neighboring steel pipes (P) obtained from step (c). 2.A construction method as claimed in claim 1, wherein the end circumferential surfaces of steel pipes (P) obtained from step (c) are matched using a force pushed by the movable other ends of the steel pipes. 3. A construction method as claimed in claim 1, wherein the conjunction portions of the inner or outer surface of the neighboring steel pipes (P) are welded by a welding robot (30a) in such a manner that only the welding unit (31) is rotated along the said conjunction portions of the inner surface of the steel pipes (P) while moving in a longitudinal direction and stopping in the interior of the steel pipes (P). 4.A construction method as claimed in claim 3, wherein the said welding robot is separately installed at an outer surface of the end portion of the steel pipe (P). 5.A construction method as claimed in claim 3, wherein the said welding robot integrally installed at the shaper (10) capable of forming the ends of the steel pipes (P) in a perfect circle shape while the welding device (33) welds, moving along the conjunction portions of the outer surface of the steel pipes (P) . 6.A construction method of a steel pipe substantially as described and shown in the description and drawings.

Documents:

5865-DELNP-2005-Abstract-(11-09-2008).pdf

5865-DELNP-2005-Abstract-(30-05-2008).pdf

5865-delnp-2005-abstract.pdf

5865-DELNP-2005-Claims-(11-09-2008).pdf

5865-delnp-2005-claims-(17-09-2008).pdf

5865-DELNP-2005-Claims-(30-05-2008).pdf

5865-delnp-2005-claims.pdf

5865-DELNP-2005-Correspondence-Others-(11-09-2008).pdf

5865-DELNP-2005-Correspondence-Others-(30-05-2008).pdf

5865-delnp-2005-correspondence-others.pdf

5865-delnp-2005-description (complete)-(17-09-2008).pdf

5865-DELNP-2005-Description (Complete)-(30-05-2008).pdf

5865-delnp-2005-description (complete)-11-09-2008.pdf

5865-delnp-2005-description (complete).pdf

5865-DELNP-2005-Drawings-(30-05-2008).pdf

5865-delnp-2005-drawings.pdf

5865-delnp-2005-form-1-(17-09-2008).pdf

5865-DELNP-2005-Form-1-(30-05-2008).pdf

5865-delnp-2005-form-1.pdf

5865-DELNP-2005-Form-13-(30-05-2008).pdf

5865-delnp-2005-form-18-(17-09-2008).pdf

5865-delnp-2005-form-18.pdf

5865-DELNP-2005-Form-2-(30-05-2008).pdf

5865-DELNP-2005-Form-26-(11-09-2008).pdf

5865-delnp-2005-form-26.pdf

5865-DELNP-2005-Form-3-(30-05-2008).pdf

5865-delnp-2005-form-3.pdf

5865-DELNP-2005-Form-5-(30-05-2008).pdf

5865-delnp-2005-form-5.pdf

5865-delnp-2005-form-6-(17-09-2008).pdf

5865-delnp-2005-form-6.pdf

5865-delnp-2005-gpa.pdf

5865-DELNP-2005-Petition-137-(11-09-2008).pdf