JP2006334617A - Automatic welding apparatus of coated steel tube, and its connection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic welding apparatus for coated steel tubes capable of performing the welding of a steel tube body and fusing of a protective sheet layer by the same equipment. <P>SOLUTION: The automatic welding apparatus for coated steel tubes welds ends of the coated steel tubes with outer circumferential surfaces of steel tube bodies 2 coated by a coating layer 4 mainly consisting of a resin, and covers the tubes with protective sheet layers 10 to perform the corrosion-proof protection, and comprises a welding means 22 to perform the welding of ends of the steel tube bodies and the fusing of the coating layer to the protective sheet layers 10, a turning means 24 to turn the welding means around the axis of the coated steel tube, a horizontal moving means 26 to move the welding means along the axial direction of the coated steel tubes, and a control means 28 to control the operation of the entire equipment. The welding of the steel tube bodies and the fusing of the protective sheet layers are performed by the same equipment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an automatic welding apparatus that connects coated steel pipes whose outer peripheral surfaces of a steel pipe main body are coated with a coating layer mainly composed of a resin, and a connection method thereof.

In general, as a gas pipe buried in the ground, in order to prevent corrosion of the pipe after being buried in the ground, the surface is covered with a coating layer of an olefin resin such as polyethylene, polypropylene, polybutene or the like. A coated steel pipe is used.
When connecting these coated steel pipes, as shown in FIG. 8, welding is performed after peeling the coating layer 4 mainly composed of resin covering the end of the coated steel pipe 2 by a predetermined length to expose the steel pipe body 6. Is done. The surface of the steel pipe body 6 from which the welded connection portion 8 is exposed is covered with a protective sheet layer 10 having an anticorrosion function to make the connection portion 8 airtight. As this method, conventionally, the protective sheet layer 10 made of a heat-shrinkable sheet or tube is provided around the connection portion 8 so as to include the surrounding coating layer 4 after welding, and the protective sheet layer 10 is provided. There has been adopted a method in which the connection portion 8 is covered by being contracted by heating by a gas burner or the like by hand, and being in close contact with the connection portion 8.

  Although this method has the advantage that it can be easily constructed on site, since welding of the steel pipe and heating of the protective sheet layer 10 are performed manually, the work takes a long time and the protective sheet layer 10 is heated uniformly. In some cases, the adhesiveness of the protective sheet 10 is reduced.

  An example of a method for solving this problem is proposed in Patent Documents 1 to 3 below. For example, Patent Document 1 discloses a fully automatic welding apparatus that enables one worker to consistently carry out from automatic inspection to automatic welding. In this automatic welding apparatus, a pipe end gripping mechanism of a steel pipe is connected by a connecting bar in which a plurality of bars are arranged in parallel, and a movable inspection / welding head is provided thereon. Then, a groove inspection sensor for inspecting the gap between the grooves butted against the rotating part and the apparent shaft misalignment and a TIG welding torch are attached, and automatic welding of the butted steel pipe is performed by one worker. It is intended to be implemented consistently.

Japanese Patent Application Laid-Open No. H10-228561 discloses that all posture welding of thin-walled piping is performed using a laser welding machine. In this laser welding machine, the rotation driving means is provided with laser welding means and position detection means, and after recognizing the position of the butt-welded joint, the position control mechanism and rotation are performed based on the position information during welding. While controlling the driving means, joint welding is performed by laser welding means.
Patent Document 3 discloses a connection method in which a transparent covering member is joined to a pipe-shaped product with a laser beam. Specifically, a pipe-shaped product that absorbs laser light is inserted into a joint that is transparent to laser light, and the laser light is irradiated from the joint side to thermally weld them together. ing.

JP 2000-334564 A JP 10-94889 A JP 2004-90628 A

  By the way, there existed the following problems in the welding method or welding apparatus indicated by above-mentioned patent documents 1-3. That is, in the welding apparatus disclosed in Patent Documents 1 and 2, when performing the anticorrosion process using a protective sheet layer such as a heat-shrinkable tube after performing the welding process using a welding machine, There has been a problem that the work for removing the tube end gripping mechanism or the like has to be performed, and the entire construction time becomes long.

Moreover, in the joining apparatus disclosed in Patent Document 3, an automatic welding apparatus as disclosed in, for example, Patent Documents 1 and 2 must be used to join the pipe. Therefore, the steel pipe welding process and the protective sheet layer are performed. In the anticorrosion process to be welded, assembling and setup change of separate devices occur, and not only the entire construction time is lengthened, but also two types of devices, a welding device and an anticorrosion device, must be prepared. There was a problem of being forced to increase costs.
The present invention has been devised to pay attention to the above problems and to effectively solve them. The objective of this invention is providing the automatic welding apparatus of the covering steel pipe which can perform the welding process of a steel pipe main body, and the welding process of a protection sheet layer with the same apparatus, and its connection method.

  The invention according to claim 1 is a coated steel pipe in which the outer peripheral surface of the steel pipe main body is welded to the ends of the coated steel pipe covered with a coating layer mainly composed of resin, and then covered with a protective sheet layer to protect against corrosion. In the automatic welding apparatus, welding means for welding the ends of the steel pipe main body and welding the coating layer and the protective sheet layer, and rotating means for rotating the welding means about the axis of the coated steel pipe; An automatic welding apparatus for coated steel pipe, comprising: horizontal moving means for moving the welding means along the axial direction of the coated steel pipe; and control means for controlling the operation of the entire apparatus. It is.

  As described above, since the welding means has the function of welding the ends of the steel pipe body and the function of welding the coating layer of the coated steel pipe and the protective sheet layer, the welding of the steel pipe body with the same apparatus. The treatment and the welding treatment of the protective sheet layer can be performed. As a result, the entire process of welding the coated steel pipe can be performed quickly and in a short time.

In this case, for example, as defined in claim 2, the welding means includes a low-power laser oscillator that oscillates laser light with an output within a range of 20 to 300 W, and a high-power that oscillates laser light with an output of 2000 W or more. And a laser oscillator.
For example, as defined in claim 3, the high-power laser oscillator includes a YAG laser element.
Further, for example, as defined in claim 4, the welding means oscillates a laser beam at an output within a range of 20 to 300 W, and an arc welding portion that performs welding while generating an arc with the steel pipe body. A low-power laser oscillator.
For example, as defined in claim 5, the low-power laser oscillator includes a semiconductor laser element.
For example, as defined in claim 6, the protective sheet layer is made of a thermoplastic resin.

The invention according to claim 7 is a coated steel pipe in which the outer peripheral surface of the steel pipe main body is welded between the ends of the coated steel pipe covered with a coating layer mainly composed of a resin, and then covered with a protective sheet layer to protect against corrosion. In the welding method, the step of removing the coating layer at the end of the coated steel pipe to expose the steel pipe main body, the step of butting the end faces of the steel pipe main body exposed at the end, and the end faces A welding step of performing welding by moving the welding means of the automatic welding apparatus according to any one of claims 1 to 5 around the axis of the coated steel pipe in a state, and at least the exposed ends of the steel pipe main body A step of providing the protective sheet layer so as to cover and covering each end of the protective sheet layer and the respective coated steel pipes by moving the welding means around the axial center and the axial direction. Layer and the Re is a connection method for coating a steel pipe characterized by having an a welding step of welding.
In this case, for example, as defined in claim 8, the protective sheet layer is made of a thermoplastic resin.

According to the automatic welding apparatus for a coated steel pipe and its connection method according to the present invention, the following excellent effects can be exhibited.
Since the welding means has the function of welding the ends of the steel pipe main body and the function of welding the coating layer and the protective sheet layer of the coated steel pipe, the welding process and protective sheet of the steel pipe main body with the same device The layer can be welded. As a result, the entire process of welding the coated steel pipe can be performed quickly and in a short time.

Hereinafter, an embodiment of an automatic welding apparatus and method for connecting a coated steel pipe according to the present invention will be described in detail with reference to the accompanying drawings.
1 is a side view showing an automatic welding apparatus for coated steel pipes according to the present invention, FIG. 2 is a side view showing an operating state of the automatic welding apparatus, FIG. 3 is a front view of the automatic welding apparatus, and FIG. FIG. 5 is a partial cross-sectional view showing a state when the coated steel pipe connecting process is completed, and FIG. 6 is a process chart showing the coated steel pipe connecting process according to the present invention.
First, the coated steel pipe 2 to be connected is covered with a coating layer 4 mainly composed of resin on the outer peripheral surface of the steel pipe body 6 having a circular cross section, as shown in FIGS. Is formed. Here, the coating layer 4 is composed of two layers, for example, a coating film 4A made of polyethylene, for example, which is coated on the outer periphery of the steel pipe body 6 via an adhesive, and a packaging film 4B made of polypropylene, for example, which is coated thereon. It is made to structure. In addition, this coating layer 4 is not limited to the said material and 2 layer structure.

  And when joining the edge parts of the above-mentioned coated steel pipe 2, as mentioned above, the said coating layer 4 of the edge part of the coated steel pipe 2 is peeled off, the steel pipe main body 6 is made into an exposed state, and this exposed steel pipe After the main bodies 6 are welded together, this portion is covered with a protective sheet layer 10 made of, for example, a thermoplastic resin, and is welded by heat. In FIG. 1, the protective sheet layer 10 has a two-layer structure of a heat-expandable anticorrosion sheet 10A made of, for example, polyethylene and a protective sheet 10B made of, for example, polyethylene. In addition to the polyethylene, for example, polypropylene, polybutene, etc. can be used as the thermoplastic resin of the protective sheet layer 10, and the material is not limited to the thermoplastic resin but is an airtight material that melts by heat. Any material can be used.

Now, in order to perform a series of welding processes and welding processes as described above, the automatic welding apparatus 20 of the present invention is used. Next, the automatic welding apparatus 20 will be described.
As shown in FIGS. 1 to 3, the automatic welding apparatus 20 includes a welding process for welding the ends of the steel pipe body 6, and a welding process for welding the coating layer 4 and the protective sheet layer 10. Welding means 22 for performing both steps, rotating means 24 for rotating the welding means 22 around the axis X1 (around the axis) of the coated steel pipe 2, and the welding means 22 in the direction of the axis X1 (axial center) A horizontal movement means 26 for movement along the direction) and a control means 28 comprising, for example, a microcomputer for controlling the operation of the entire apparatus.

  Specifically, the welding means 22 includes a laser oscillation unit 30 that oscillates laser light and a laser irradiation unit 32 that directly irradiates an object such as welding with laser light, both of which propagate laser light. Are connected by an optical fiber 34. As shown in FIG. 4, the laser oscillation unit 30 includes a high-power laser oscillator 36 that generates a high-power laser beam L1 for welding a steel pipe, and a low-power laser that generates a low-power laser beam L2 for resin welding. And an oscillator 38. The high-power laser oscillator 36 is made of, for example, a YAG laser element, and can output high-power laser light L1 of, for example, 2000 W (watts) or more. On the other hand, the low-power laser oscillator 38 is made of, for example, a semiconductor laser element, and can output low-power laser light L2 within a range of 20 to 300 W, for example.

  The laser beams L1 and L2 are selectively output, output in one direction by an optical element 40 such as a polarization beam splitter, condensed by a condenser lens 42, and propagated into the optical fiber 34. ing. The laser irradiation unit 32 includes, for example, a laser irradiation torch 44 having an objective lens (not shown), and thereby irradiates laser light.

  On the other hand, the rotating means 24 can be moved only in a direction in which it is slidably mounted on the guide rail 46 and rotated about its axis, and is attached so as to surround the periphery of the coated steel pipe 2. A base portion 48 and a rotation driving portion 50 provided on the base portion 48 and moving the base portion 48 in the direction around the axis. As shown in FIG. 3, the guide rail portion 46 is divided into two arcs and is detachably attached to the outer periphery of the coated steel pipe 2. Specifically, a plurality of, in the illustrated example, six short struts 52 are arranged at substantially equal intervals along the circumferential direction on the guide rail portion 46, and the inner peripheral side surface of each strut 52 is covered. The steel pipe 2 is supported in direct contact with the outer peripheral surface.

  A rack 54 is provided in an annular shape along the outer peripheral surface of the guide rail 46. The rack 54 is engaged with a pinion 56 that is rotatably supported on the base portion 48 side, and the pinion 56 is connected to an electric motor 58. The pinion 56 and the electric motor 58 constitute the rotational drive unit 50. By rotating the pinion 56 by the electric motor 58, the base portion 48 is moved around the axis X1 of the coated steel pipe 2. It can be done.

  The base portion 48 is provided with a horizontal moving portion 60 that constitutes a part of the horizontal moving means 26. A support rod 62 that can be moved forward and backward in the horizontal direction is inserted into the horizontal moving unit 60, and the laser irradiation unit 32 is attached to the tip of the support rod 62. A slide mechanism 64 is provided at the joint between the support rod 62 and the laser irradiation unit 32 so as to be slidable in the direction of the axis X1 (radial direction). The laser irradiation unit 32 is covered with the coated steel pipe 2. It is possible to adjust the focus of the laser beam by moving in the radial direction.

  Further, a pair of pressing members 66 are provided at a lower end side portion in FIG. 1 of the laser irradiation unit 32 with a slight gap therebetween (see FIG. 3). The pressing member 66 has a roller 68 that is pressed in the direction of the axial center X1 by a compression spring (not shown) so as to be rotatable. The roller 68 comes into contact with the surface of the coated steel pipe 2 and is connected to the axial center X1. It can roll in the circumferential direction while pressing in the direction. The operation of the entire apparatus is controlled by a control means 28 (see FIG. 1) made of, for example, a microcomputer.

Next, a method for connecting a coated steel pipe according to the present invention performed using the automatic welding apparatus configured as described above will be described.
First, the basic operation of the automatic welding apparatus 20 will be described.
In order to generate welding energy, laser light is generated by the laser oscillation unit 30 of the welding means 22. In this case, when welding the steel pipe main bodies 6, the high-power laser light L 1 is output from the high-power laser oscillator 36. In addition, when the resin such as the protective sheet layer 10 is welded together, the low output laser light L2 is output from the low output laser oscillator 38 (see FIG. 4). Radiation from the laser irradiation torch 44 toward the connection target location.

  Further, when the laser irradiation unit 32 is moved along the direction of the axis X1, that is, along the longitudinal direction of the coated steel pipe 2, by driving the horizontal moving unit 60 of the horizontal moving unit 26 as shown in FIG. This is done by moving the support rod 62 forward or backward in the horizontal direction. Further, in order to adjust the focal position of the laser light emitted toward the connection target location, the laser irradiation unit 32 is made to move the coated steel tube 2 by driving the slide mechanism 64 provided at the tip of the support rod 62. Move in the radial direction to adjust the focal position.

  Furthermore, in order to move the laser irradiation unit 32 in the circumferential direction of the coated steel pipe 2, that is, around the axis X1, the electric motor 58 in the rotation driving unit 50 of the rotating unit 24 is rotationally driven. As a result, the pinion 56 rotated by the electric motor 58 moves along the rack 54 disposed along the outer periphery of the coated steel pipe 2, and as a result, the base portion 48 and the support rod 62 are moved to the rack portion 54. The laser irradiation part 32 supported via the inner surface moves integrally along the circumferential direction of the coated steel pipe 2.

  Next, the actual connection process between the coated steel pipes 2 will be described. FIG. 5 shows a state when the coated steel pipe connection process is completed, and the coating layer 4 composed of the coating film 4A and the packaging film 4B is peeled off at the ends of the two coated steel pipes 2 and ends. After the parts are butt welded, this part is covered with a protective sheet layer 10 composed of the anticorrosion sheet 10A and the protective sheet 10B, and the upper protective sheet 10B is thermally welded to the lower resin and joined. Therefore, welded portions 72A at both ends of the protective sheet 10B and the coating film 4A are formed.

  Next, specific steps of the connection step will be described with reference to the flowchart shown in FIG. First, two coated steel pipes 2 to be connected as shown in FIG. 6 (A) are prepared, and as shown in FIG. 6 (B), the coating layer 4 at the end of the coated steel pipe 2 has a predetermined length. The steel pipe body 6 is peeled off by peeling off.

  Next, as shown in FIG. 6C, the ends of the steel pipe main body 6 of the coated steel pipe 2 whose ends are exposed are brought into contact with each other, and the automatic welding apparatus 20 is attached to the coated steel pipe 2, In this state, the end portions are welded with the high-power laser beam L1 while moving the laser irradiation torch 44 around the axis X1 along the abutting portion. As a result, a weld 74 is formed along the joint end. As described above, the laser beam L2 of 2000 W or more may be used for such welding. For example, a welding apparatus capable of welding a steel plate having a thickness of 6 mm at a speed of 1 m / min using a laser beam of 3500 W is already known. It is possible to weld a steel plate having a thickness of about 10 mm at the maximum.

As described above, if the welding between the steel pipe main bodies 6 is completed, as shown in FIG. 6 (D), the outer peripheral side of the coating film 4A positioned on the inner peripheral side of the coating layer 4 is positioned. The direction of the packaging film 4B to be peeled off is made longer to obtain a stepped cross-sectional shape.
And as shown in FIG.6 (E), the anti-corrosion sheet | seat 10A which is a part of the protection sheet layer 10 is provided so that the said welding part 74 may be covered. Both end portions of the anticorrosion sheet 10A are in a state of being overlapped with the end portions of the coating film 4A. For example, a self-bonding tape (not shown) is wound around both ends of the anticorrosion sheet 10A and bonded to the lower layer.

  As this anticorrosion sheet 10A, for example, a tube-like polyethylene having a heat stretchability, in which butyl rubber or the like is previously applied on the inside, can be used. It is better to leave it temporarily. And the above-mentioned anticorrosion sheet | seat 10A is heat-shrinked by roasting with a burner etc. in the state with which the said welding part 74 was mounted | worn, and is made into a close contact state with a lower layer.

  Next, as shown in FIG. 6F, a protective sheet 10B which is a part of the protective sheet layer 10 is provided so as to completely cover the entire anticorrosion sheet 10A. The protective sheet 10B is longer than the anticorrosion sheet 10A, and both end portions thereof are in a state of being overlaid with the coating film 4A. Polyethylene can be used as the protective sheet 10B.

  Next, as shown in FIG. 6G, both ends of the protective sheet 10B are heated and melted by the low-power laser light L2 emitted from the laser irradiation torch 44, and the protective sheet 10B and the lower layer are coated. The film 4A is welded. As a result, weld portions 72A are formed at both ends of the protective sheet 10B. For such welding, the low-power laser beam L2 in the range of 20 to 300 W may be used as described above. In this way, the automatic welding apparatus 20 is removed from the coated steel pipe 2 and the connection work of the coated steel pipe 2 is completed.

  As described above, the high-power laser oscillator 36 and the low-power laser oscillator 38 are provided in the laser oscillation part 30 of the welding means 22, the function of welding the ends of the steel pipe body 6 to the welding means 22, and the coated steel pipe 2. Since the function of welding the coating layer 4 and the protective sheet layer 10 is provided, the welding process of the steel pipe body 6 and the welding process of the protective sheet layer 10 can be performed with the same apparatus. As a result, the entire process of welding the coated steel pipe 2 can be performed quickly and in a short time.

  In the above embodiment, the welding means 22 is provided with the high-power laser oscillator 36 for connecting the steel pipe body 6, but an arc welding portion may be provided instead. FIG. 7 is a schematic view showing a modification of such welding means 22. 7, the same components as those shown in FIG. 4 are denoted by the same reference numerals. As described above, here, since the arc welding portion 80 is provided instead of the high output laser oscillator 36, only the low output laser oscillator 38 is provided in the laser oscillation portion 30.

Moreover, the said arc welding part 80 performs MAG welding, TIG welding, etc., for example. For example, when TIG welding is performed as the arc welded portion 80, the arc welded portion 80 includes a welding wire reel 84 in which a drawn-out welding wire 82 is wound and stored, an arc welding torch 86, and an arc power supply 88. Have. The arc welding torch 86 is provided side by side so as to be adjacent to the laser irradiation torch 44 of the laser irradiation unit 32. The arc welding torch 86 generates an arc 90 between the welding object and the welding wire reel 84. The welding wire 82 to be fed is melted so that the steel pipe main bodies 6 can be connected to each other.
Moreover, in the said Example, although both the coating layer 4 and the protection sheet 10 are made | formed by 2 layer structure, it is not limited to this layer structure, Moreover, also about each structural material, it is the material demonstrated above. It is not limited.

It is a side view which shows the automatic welding apparatus of the covering steel pipe which concerns on this invention. It is a side view which shows the operation state of an automatic welding apparatus. It is a front view which shows an automatic welding apparatus. It is a schematic diagram which shows the welding means of an automatic welding apparatus. It is a fragmentary sectional view which shows a state when the connection process of a covering steel pipe is completed. It is process drawing which shows the connection process of the coated steel pipe which concerns on this invention. It is a schematic diagram which shows the modification of a welding means. It is a perspective view which shows the state in the case of connecting covering steel pipes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Coated steel pipe 4 Coated layer 6 Steel pipe main body 10 Protective sheet layer 20 Automatic welding apparatus 22 Welding means 24 Rotating means 26 Horizontal moving means 28 Control means 30 Laser oscillation part 32 Laser irradiation part 36 High output laser oscillator 38 Low output laser oscillator 44 Laser Irradiation torch 80 Arc welding part 86 Arc welding torch X1 axis

Claims (8)

In the automatic welding device of the coated steel pipe that welds the ends of the coated steel pipe whose outer peripheral surface of the steel pipe main body is covered with a coating layer mainly composed of a resin, and then covers and protects with a protective sheet layer,
Welding means for performing welding between ends of the steel pipe main body and welding of the covering layer and the protective sheet layer;
Rotating means for rotating the welding means about the axis of the coated steel pipe;
Horizontal moving means for moving the welding means along the axial direction of the coated steel pipe;
Control means for controlling the operation of the entire apparatus;
An automatic welding apparatus for a coated steel pipe, characterized in that it is configured to include: The welding means includes a low-power laser oscillator that oscillates laser light at an output within a range of 20 to 300 W
The automatic welding apparatus for coated steel pipe according to claim 1, further comprising a high-power laser oscillator that oscillates laser light with an output of 2000 W or more.   3. The automatic welding apparatus for coated steel pipe according to claim 2, wherein the high-power laser oscillator has a YAG laser element. The welding means is an arc welding portion that performs welding while generating an arc with the steel pipe main body,
A low-power laser oscillator that oscillates laser light at an output within a range of 20 to 300 W;
The automatic welding apparatus for coated steel pipes according to claim 1, comprising:   The automatic welding apparatus for coated steel pipe according to any one of claims 2 to 4, wherein the low-power laser oscillator includes a semiconductor laser element.   The said protective sheet layer consists of thermoplastic resins, The automatic welding apparatus of the coated steel pipe in any one of Claim 1 thru | or 5 characterized by the above-mentioned. In the welding method of the coated steel pipe, the outer peripheral surface of the steel pipe body is welded between the ends of the coated steel pipe covered with a coating layer mainly composed of resin, and then covered with a protective sheet layer to protect against corrosion.
Removing the coating layer at the end of the coated steel pipe to expose the steel pipe body; and
A process of abutting the end faces of the steel pipe body exposed at the ends;
A welding step of performing welding by moving the welding means of the automatic welding apparatus according to any one of claims 1 to 5 around the axis of the coated steel pipe in a state in which the end faces are butted together;
Providing the protective sheet layer so as to cover at least the exposed ends of the steel pipe body; and
Welding steps for welding the both end portions of the protective sheet layer and the respective coating layers of the respective coated steel pipes by moving the welding means around the axial center and the axial direction;
A method for connecting a coated steel pipe, comprising: The method for connecting a coated steel pipe according to claim 7, wherein the protective sheet layer is made of a thermoplastic resin.

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