JP4000166B2 - Manufacturing method of steel pipe with protrusions - Google Patents

Description

The present invention relates to the production how the nubbed steel pipe using the overlay welding.

  In the civil engineering or construction field, a composite structure in which a steel pipe is filled with concrete or a steel pipe is embedded in the concrete is used for a building column or a foundation pile. In the composite structure of these steel pipes and concrete, in order to increase the adhesion between the steel pipe and concrete, a protrusion is provided on the surface of the steel pipe.

  As one method for forming protrusions on the surface of a steel pipe, overlay welding has been conventionally used. For example, in Patent Document 1, a pair of contact plates are arranged at intervals on the inner surface or outer surface of a steel pipe, and these contact plates are moved relative to the inner surface or outer surface of the steel tube while being moved between these contact plates. A technique for forming protrusions by overlay welding is disclosed.

  Specifically, as shown in FIG. 8, when the protrusions P are formed in the circumferential direction on the inner surface of the steel pipe 1, the steel pipe 1 is first placed sideways, and a pair of contact plates 20, 20 are placed on the inner surface of the steel pipe 1. Place. Then, the welding wire 6 of the welding torch 5 is inserted between the pair of contact plates 20 and 20, and the steel pipe 1 is rotated while rotating the steel pipe 1 in the circumferential direction (direction perpendicular to the surface on which the drawing is drawn). An arc is generated in the space formed by the inner surface of the steel plate and the contact plates 20 and 20, and overlay welding is performed downward. For welding, gas metal arc welding such as carbon dioxide arc welding, MAG welding, or MIG welding can be used as appropriate.

JP 2005-193245 A

  By the way, when manufacturing a projection having a high height (for example, the projection width is constant) using a welding technique as disclosed in Patent Document 1, for example, there is a multi-layer welding method in which welding is stacked in a plurality of stages. In this case, if the contact plates 20 and 20 having a height higher than the width are used, the welding torch 5 interferes with the contact plates 20 and 20 as shown in FIG. The problem that it becomes impossible to manufacture is produced. Of course, in this case, as shown in FIG. 10, it is possible to weld the first layer on the inner surface of the steel pipe 1 by lengthening the welding wire 6, but the welding wire 6 is lengthened. Then, the position of the welding wire 6 with respect to the steel pipe 1 becomes unstable, the welding position is not stable, and a situation may occur in which the contact plate 20 is welded to the steel pipe 1. Further, during welding, the long welding wire 6 may swing in the space between the contact plates 20 and 20, and as a result, a situation may occur in which the welding voltage becomes unstable.

The present invention has been made in view of the above circumstances, to provide a manufacturing how the nubbed steel pipe can be easily and economically forming a height higher projections against the steel pipe with respect to the width For the purpose.

  In order to achieve the above object, the method for manufacturing a steel pipe with protrusions according to claim 1 is a method of manufacturing a steel pipe with protrusions by forming protrusions on the inner surface or outer surface of the steel pipe by overlay welding, and the longitudinal direction thereof. A pair of caulking plates whose heights change along the direction are arranged at an interval on the inner surface or outer surface of the steel pipe, and the caulking plate and the inner surface or outer surface of the steel pipe are moved relative to each other while moving relative to each other. A first projection is formed by welding at a first position in the space, and at a second position where the height of the contact plate is higher than the first position, the contact plate and the inner surface or the outer surface of the steel pipe are relative to each other. Forming a second projection by welding on the first projection while moving the first projection.

  In the method of manufacturing a steel pipe with projections according to claim 1, since the contact plate whose height changes along the longitudinal direction is used, the welding position and the welding are increased with the number of times of welding in the multi-layer welding. By changing the height, it becomes possible to easily and economically manufacture protrusions having a height (for example, constant width) with respect to the width in the best form.

  In the present invention, since the contact plate whose height changes along the longitudinal direction is used, the welding position and the welding height can be changed with the number of weldings in the multi-layer welding. For this reason, even when forming a projection with a high height, it is possible to avoid a situation in which the welding torch interferes with the backing plate or the welding position becomes unstable due to a long welding wire. Therefore, it is possible to easily and economically manufacture a projection having a high height in the best form.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are views showing a method of manufacturing a steel pipe with projections according to an embodiment of the present invention. FIG. 1 is a side sectional view, and FIG. 2 is an enlarged perspective view of a main part. As shown in these drawings, in order to form the protrusions P on the inner surface of the steel pipe 1 in the circumferential direction, first, the steel pipe 1 is placed sideways, and a pair of abutments are placed on the lower side of the inner surface of the steel pipe 1. Plates 2 and 2 are arranged. In this case, the pair of contact plates 2 and 2 are arranged in parallel with an interval (with a welding space) on the inner surface of the steel pipe 1.

  As shown in FIG. 3, the contact plate 2 has a distal end surface 2a and a proximal end surface 2b at both ends in the longitudinal direction, and the upper surface 2c is inclined so that the height changes along the longitudinal direction. Is formed. Chamfering is applied to the corner of the contact plate 2 on the welding torch side. The backing plate 2 of the present embodiment has a height that increases continuously from the distal end surface 2a to the proximal end surface 2b, but the height may change stepwise. Moreover, although the upper surface 2c has extended linearly in the same figure, the upper surface 2c may comprise the curve. Further, the bottom surface 2 d of the backing plate 2 is preferably formed in an arc shape along the inner surface of the steel pipe 1. In addition, as the backing plate 2, a water-cooled copper plate (water-cooled copper plate) is usually used, but a ceramic plate or the like can also be used. In addition, the angle (gradient) θ formed by the upper surface 2c with respect to the horizontal plane is determined by the diameter of the steel pipe 1 and the height of the necessary projections P, but considering the movement of the welding torch described later, it is about 10 ° to 20 °. It is preferable that the range is set.

  As described above, when the pair of contact plates 2 and 2 are arranged in parallel with an interval on the inner surface of the steel pipe 1, subsequently, as shown in FIG. 1, the boom 4 of the welding apparatus 3 located outside the steel pipe 1. Is inserted into the steel pipe 1, and the welding wire 6 of the welding torch 5 provided at the tip of the boom 4 is inserted between the pair of contact plates 2 and 2. Then, while the steel pipe 1 is rotated in the circumferential direction, an arc is generated in the space (welding space) formed by the inner surface of the steel pipe 1 and the contact plates 2 and 2 to perform overlay welding. The contact plates 2 and 2 are supported by the boom 4 and the like. For welding, carbon metal arc welding, MAG welding, gas metal arc welding such as MIG welding, or the like can be used as appropriate.

  It is necessary to finish the side surface of the contact plate 2 that forms the space for overlay welding in order to form a protrusion P having a straight portion on the side portion of the cross-sectional shape. In order to make the angle (rise angle) formed between the side surface of the protrusion P formed on the inner surface of the steel pipe 1 and the inner surface of the steel pipe 1 form a predetermined acute angle, a predetermined angle may be given to the side surface of the backing plate 2. it can. If the angle of the side surface of the backing plate 2 exceeds 90 °, it will be difficult to remove the backing plate 2 after the end of welding, so it is set to about 60 to 90 °, for example.

  The height of the backing plate 2 needs to be higher than the height of the projection P to be formed, but if it is too high, the cost of the backing plate 2 will be excessive, and the welding arc will be difficult to see, resulting in poor workability. Therefore, it is preferable to set the height appropriately. In addition, if the distance between the contact plates 2 and 2 is too narrow, damage due to the welding arc occurs, so it is necessary to be about 5 mm or more. It is not preferable to be too wide. The width of the projection P formed on the inner surface of the steel pipe 1 is substantially equal to the interval between the contact plates 2 and 2.

  In order to obtain a continuous projection on the inner surface of the steel pipe 1, it is necessary to relatively move the inner surface of the steel pipe 1, the welding torch 5 and the pair of contact plates 2 and 2 by rotating the steel pipe 1, At this time, if the lengths of the contact plates 2 and 2 are short, the molten metal flows out from the lateral (longitudinal direction of the contact plate 2) opening. On the other hand, if the contact plates 2 and 2 are too long, the frictional force between the side surfaces of the projections P formed by solidification of the molten metal and the contact plate 2 becomes large, and it becomes difficult to move stably. Since it becomes difficult to maintain the adhesiveness with the backing plate 2, it is necessary to make it an appropriate length. The length (longitudinal dimension) of the backing plate 2 usually needs to be about 25 mm or more and about 120 mm or less, and is preferably about 100 mm or less, more preferably about 80 mm or less in consideration of workability.

  Next, a method for forming the projections P on the inner surface of the steel pipe 1 by overlay welding (multilayer welding) using the contact plates 2 and 2 having the above configuration will be specifically described.

  First, as shown in FIGS. 3 and 4, the first position in the space between the contact plates 2 and 2 close to the tip surface 2a, that is, the position where the height of the contact plate 2 is relatively low (height H1 In this state, the welding torch 5 is disposed, and in this state, the contact plates 2 and 2 and the inner surface of the steel pipe 1 are relatively moved (in this embodiment, the steel tube 1 is rotated), while the contact plates 2 and 2 are moved. Weld in the space between. As a result, as shown in FIG. 7, a first layer projection (first projection) P <b> 1 is formed over the inner periphery of the steel pipe 1.

  Subsequently, as shown in FIG. 5, the second position in which the height of the contact plates 2 and 2 is higher than the first position, that is, the height moved to the base end face 2b side from the first position. The welding torch 5 is rearranged at the position H2, and in this state, the first layer is moved within the space between the contact plates 2 and 2 while relatively moving the contact plates 2 and 2 and the inner surface of the steel pipe 1. Welding is performed on the protrusion P1. As a result, as shown in FIG. 7, a second layer protrusion (second protrusion) P <b> 2 higher than the first layer protrusion P <b> 1 is formed over the inner periphery of the steel pipe 1.

  Thereafter, as shown in FIG. 6, the welding torch 5 is moved again to the third position where the height of the contact plates 2, 2 is higher than the second position, that is, the position near the base end surface 2 b is H 3. In this state, welding is performed on the projection P2 of the second layer in the space between the contact plates 2 and 2 while relatively moving the contact plates 2 and 2 and the inner surface of the steel pipe 1. As a result, as shown in FIG. 7, a third layer protrusion (third protrusion) P <b> 3 higher than the second layer protrusion P <b> 2 is formed over the inner periphery of the steel pipe 1.

  In the above manufacturing method, the appropriate length h of the welding wire 6 is 15 to 25 mm. Further, at the time of welding, it is sufficient that the contact plates 2 and 2 and the welding torch 5 move relatively, and the welding torch 5 and the contact plates 2 and 2 are moved with respect to the steel pipe 1 without rotating the steel pipe 1. You may let them.

  As described above, in the present embodiment, since the contact plates 2 and 2 whose height changes along the longitudinal direction are used, as shown in FIG. Thus, the welding position and the welding height can be changed (the positions of the welding torch 5 and the welding wire 6 for forming the projection P into the best shape can be secured). Therefore, even when the projection P having a high height is formed, a situation in which the welding torch 5 interferes with the contact plates 2 and 2 or the welding position becomes unstable due to the long welding wire 6 is avoided. Thus, the projection P having a height higher than the width can be easily and economically manufactured in the best form.

  Needless to say, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the scope of the invention. For example, in the above-described embodiment, the steel pipe 1 is rotated in order to move the contact plates 2 and 2 and the welding torch 5 relative to the inner surface of the steel pipe 1, but instead of this, the steel pipe 1 is not rotated. The contact plates 2 and 2 and the welding torch 5 may be moved. When it is desired to form a spiral protrusion on the inner surface of the steel pipe 1, the steel pipe 1 may be moved in the axial direction of the steel pipe 1 while rotating the steel pipe 1, or the steel pipe 1 may be rotated while rotating. The plates 2 and 2 and the welding torch 5 may be moved in the axial direction of the steel pipe 1. Moreover, when it is desired to form a plurality of protrusions at once, the plurality of welding torches 5 and the contact plates 2 and 2 disposed on both sides of each welding torch 5 may be used. Further, the protrusion P can be formed continuously or intermittently. The present invention can also be applied to the case where protrusions are formed outside the steel pipe.

It is a sectional side view which shows the manufacturing method of the steel pipe with a protrusion which concerns on embodiment of this invention. It is an expansion perspective view of the principal part of FIG. It is a side view of the backing plate which concerns on embodiment of this invention. It is a figure which shows the state which is welding in the 1st position where the height of a backing plate is low. It is a figure which shows the state which is welding in the 2nd position where the height of a backing plate is higher than a 1st position. It is a figure which shows the state which is welding in the 3rd position where the height of a backing plate is higher than a 2nd position. It is a figure for demonstrating the multilayer build-up welding which rotates a steel pipe and welds in each of the 1st thru | or 3rd position. It is a figure which shows the method of forming low protrusion in a steel pipe using the conventional patch plate. It is a figure which shows a mode that a welding torch and a contact plate interfere in the case of forming a high protrusion in a steel pipe using the conventional contact plate. It is a figure which shows a mode that a long welding wire is swinging between the contact plates in the case where a projection having a high height is formed on a steel pipe using a conventional contact plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel pipe 2 Catch plate P Protrusion P1 1st protrusion P2 2nd protrusion

Claims (1)

A method of manufacturing a steel pipe with protrusions by forming protrusions on the inner surface or outer surface of the steel pipe by overlay welding,
A pair of contact plates whose height varies along the longitudinal direction are arranged on the inner surface or outer surface of the steel pipe at an interval,
Forming a first protrusion by welding at a first position in the space between the contact plates while relatively moving the contact plate and the inner surface or the outer surface of the steel pipe;
A second position is formed by welding on the first protrusion while relatively moving the contact plate and the inner surface or the outer surface of the steel pipe at a second position where the height of the contact plate is higher than the first position. Forming protrusions,
The manufacturing method of the steel pipe with a protrusion characterized by the above-mentioned.

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