JP6104648B2 - Flatness correction method - Google Patents

Description

The present invention relates to a flatness correction method for correcting the flatness of the end face of the steel pipe sheet pile, in which a joint to an adjacent pipe adjacent in the radial direction is welded to the outer peripheral surface of the steel pipe along the longitudinal direction. about the law.

  Conventionally, as this type of steel pipe sheet pile technology, for example, the case of a steel pipe sheet pile provided with joints on both side surfaces of the steel pipe will be described as an example. As shown in FIG. Before the main fixing by welding, a rib member 20 having a cross-shaped cross section composed of a rib portion 20A extending between joint fitting positions in the inner space of the steel pipe 1 and a rib portion 20B orthogonal thereto is welded to the steel pipe. 1 was fixed to the inner peripheral surface of No. 1, and then the full length of the joint 3 was attached to the steel pipe 1 by welding (see, for example, Patent Document 1).

JP 2009-166084 A (FIGS. 1 and 2)

Conventionally, when joints are attached to both side surfaces of a steel pipe by welding, it is known that one of the effects of thermal contraction of the steel pipe sheet pile accompanying it appears on the pipe end face as shrinkage strain in the length direction.
Specifically, the vicinity of the joint attachment extension line on the pipe end surface tends to be recessed more than the other parts, and as a result, the flatness of the pipe end surface is deteriorated.
Incidentally, the flatness means the maximum value of the gap when the reference flat plate is applied to the tube end surface, and the larger the value, the more uneven the tube end surface and the lower the flatness.
And the adverse effect of poor flatness at the pipe end surface is that the distance between the joint surfaces is different when using another welded pipe that welds both steel pipes in the axial direction. There is an increase in variation, which is not preferable because there is a risk of causing a joint failure between steel pipes. In addition, when a mechanical joint is used at a joint between steel pipes, there is a risk that the fitting connection cannot be performed normally.
Therefore, in the conventional steel pipe sheet pile technology, the rib member is fixed to the inner peripheral portion of the steel pipe as described above, so that the contracting force in the pipe length direction acting on the joint welding location is distributed to other peripheral portions via the rib member. This prevents the formation of a large dent and reduces the flatness of the tube end face.
However, according to such a conventional steel pipe sheet pile technology, it is necessary to perform a welding operation while disposing the rib member on the inner peripheral portion of the steel pipe, and there is a problem that it takes time and cost.

  Accordingly, an object of the present invention is to provide a steel pipe sheet pile technology capable of improving the flatness of the end face of the steel pipe sheet pile while eliminating the above-mentioned problems and suppressing labor and cost.

  1st characteristic structure of this invention is the flatness which corrects the flatness of the end surface of the said steel pipe sheet pile for the steel pipe sheet pile by which the joint with an adjacent pipe is welded along the longitudinal direction on the outer peripheral surface of a steel pipe. In the straightening method, the steel pipe is caused to shrink by heating at least a part of the entire circumference of the steel pipe where the joint is not provided, and the shrinkage of the material accompanying a temperature drop after heating is caused. It exists in improving the flatness of the end face of a sheet pile.

According to the first characteristic configuration of the present invention, the entire circumference of the steel pipe is heated at least a part of the circumferential range where the joint is not provided. It can also be caused to occur in the circumferential range where the joint is not provided, and the drop of the end surface dent between the circumferential range where the joint is provided and the circumferential range where the joint is not provided can be reduced. The flatness of the tube end face can be improved.
In addition, as described above, the work itself is only to heat at least a part of the circumferential range where the joint is not provided in the entire circumference of the steel pipe, so that the flatness is corrected easily and quickly. be able to.
Furthermore, compared with the conventional method, since it is not necessary to arrange an extra member such as a rib member in the inner space of the steel pipe, it is possible to reduce the cost, and in the inner space of the steel pipe, for example, Even when placing aggregate, concrete, or the like, there is no obstacle to the work, so the work can be carried out smoothly.
Moreover, since the circumferential range in which the joint is provided is not heated in the entire circumference of the steel pipe, there is no possibility of promoting thermal shrinkage in the portion, and due to the shrinkage of the material caused by heating in the circumferential range in which the joint is not provided. The flatness of the pipe end face can be improved by a remarkable effect.
Furthermore, there is no risk of quality deterioration due to heating of the welded portion between the steel pipe and the joint.

  According to a second characteristic configuration of the present invention, the heating position of the steel pipe is set in a range on the end of the steel pipe end to be flattened from the center in the longitudinal direction of the steel pipe within the circumferential range. is there.

The effect of heat shrinkage due to heating of the steel pipe tends to attenuate as it spreads around the heating position, so the heating position is closer to the free end than the center of the steel pipe, and the influence on the end is less. It appears greatly.
According to the 2nd characteristic structure of this invention, the heating position of the said steel pipe is set to the range of the steel pipe end part side of flatness correction object from the center part in the longitudinal direction of the said steel pipe within the said circumferential range. Therefore, compared with heating the central portion, the effect of heat shrinkage can be greatly utilized for end face correction, and the flatness of the pipe end face can be easily improved.

  According to a third characteristic configuration of the present invention, a heating position in the circumferential direction of the steel pipe is a circumferential position farthest from the joint, and the joint is provided at a plurality of locations in the circumferential direction of the steel pipe. And when the heat input of the welding of the said joint adjacent to the circumferential direction differs, it exists in the place which correct | amends the said reference position to the said joint side with little heat input according to the heat input of welding of both joints.

It has been found that the amount of shrinkage in the tube axis direction of the steel pipe that occurs when the joint is attached to the steel pipe by welding increases as the amount of heat input during welding or the amount of deposited metal increases. Further, the distribution of the shrinkage amount (shrinkage amount in the tube axis direction) in the circumferential direction of the steel pipe tended to be maximized at the position where the joint was welded and the circumferential position furthest away from the joint was minimized.
Therefore, in order to improve the flatness of the end face of the steel pipe sheet pile, it can be realized by contracting the circumferential range that is the minimum (or 0) of the contraction amount so as to approach the contraction amount at the joint position. .
According to the third characteristic configuration of the present invention, since the circumferential position farthest from the joint is used as the heating reference position, the minimum circumferential range of the shrinkage can be heated and shrunk, and the plane of the end face of the steel pipe sheet pile The degree can be improved. This is effective when only one joint is attached, or even when a plurality of joints are attached, the amount of heat input from welding of joints adjacent in the circumferential direction is the same.
Also, if the heat input of the joints adjacent in the circumferential direction is different, the heating reference position is corrected to the joint side with the smaller heat input according to the heat input of the welds of both joints. The flatness of the steel pipe sheet pile can be improved more efficiently and accurately by heating and shrinking the circumferential range where the amount is minimum.

  A fourth characteristic configuration of the present invention is that the heating temperature of the steel pipe is set to an upper limit side in a range where the mechanical properties of the material of the steel pipe do not change before and after heating.

The higher the heating temperature of the steel pipe, the higher the heat shrinkage after the temperature drop, so high temperature heating is preferable from the viewpoint of improving the flatness of the pipe end face.
On the other hand, if the heating temperature is too high, there is a risk that the mechanical properties of the steel pipe material will change, and it may be impossible to ensure the predetermined physical properties of the entire steel pipe sheet pile.
According to the fourth characteristic configuration of the present invention, since the steel pipe is heated at the upper limit temperature within the range where the mechanical properties do not change, the predetermined mechanical properties of the steel pipe sheet pile material can be maintained, but the maximum within the range. Thus, the flatness can be corrected efficiently.

The outer peripheral surface of the steel pipe, a steel pipe sheet pile joint between adjacent pipes are welded along the longitudinal direction, of the entire periphery of the steel tube, at least a portion of the circumferential extent of the coupling is not provided , thereby causing shrinkage of the material due to the temperature drop after heating, according to the heated portion that the flatness is improved Oh Ru configuration provided in an end surface of the steel pipe, the steel pipe material heated portion results By contraction, the displacement tendency in the longitudinal direction of the steel pipe in the circumferential range where the joint is not provided on the end face of the steel pipe can be matched with the displacement tendency in the circumferential range where the joint is provided. As a result, the flatness of the pipe end face is improved, the adhesiveness with another steel pipe sheet pile connected in the longitudinal direction is improved, and the connection performance between the steel pipe sheet piles can be maintained well.
In addition, as described above, the heating operation itself of the heated portion only heats at least a part of the entire circumference of the steel pipe where no joint is provided. Degree correction can be performed, and the increase in cost can be suppressed.
Furthermore, compared with the conventional method, since it is not necessary to arrange an extra member such as a rib member in the inner space of the steel pipe, it is possible to reduce the cost, and in the inner space of the steel pipe, for example, Even when placing aggregate, concrete, or the like, there is no obstacle to the work, so the work can be carried out smoothly.
Moreover, since the circumferential range in which the joint is provided is not heated in the entire circumference of the steel pipe, there is no possibility of promoting thermal shrinkage in the portion, and due to the shrinkage of the material caused by heating in the circumferential range in which the joint is not provided. The flatness of the pipe end face can be improved by a remarkable effect.
Furthermore, there is no risk of quality deterioration due to heating of the welded portion between the steel pipe and the joint.

Perspective view showing steel pipe sheet pile Partially cutaway perspective view showing fitting state of mechanical joint member Cross section of steel pipe sheet pile Side view of main part showing deformation of end face of steel pipe sheet pile The diagram which shows the deformation | transformation condition of the end surface of the steel pipe sheet pile of 1st Embodiment Side view showing the heating area of the steel pipe sheet pile of the first embodiment The diagram which shows the deformation | transformation condition of the convex-type mechanical coupling member side end surface of the steel pipe sheet pile of 2nd Embodiment. The diagram which shows the deformation | transformation condition of the concave type machine joint member side end surface of the steel pipe sheet pile of 2nd Embodiment. Side view showing the heating area of the steel pipe sheet pile of the second embodiment The diagram which shows the deformation | transformation condition of the convex-type mechanical coupling member side end surface of the steel pipe sheet pile of 3rd Embodiment. The diagram which shows the deformation | transformation condition of the concave type machine joint member side end surface of the steel pipe sheet pile of 3rd Embodiment. Side view showing the heating area of the steel pipe sheet pile of the third embodiment Cross section of the main part showing the sheet pile joint member Cross-sectional view showing the heating area of the steel pipe sheet pile of another embodiment Cross-sectional view showing the heating area of the steel pipe sheet pile of another embodiment Side view showing heating area of steel pipe sheet pile of another embodiment Side view showing heating area of steel pipe sheet pile of another embodiment Explanatory drawing which shows the steel pipe sheet pile of a prior art example

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the parts indicated by the same reference numerals as those in the conventional example indicate the same or corresponding parts.

FIG. 1 shows an embodiment of a steel pipe sheet pile P that is an object of the steel pipe sheet pile technology of the present invention.
The steel pipe sheet piles P are attached to both ends of the steel pipe 1 by welding, respectively, with mechanical joint members 2 with other steel pipes 1 connected in the axial direction of the pipe, and are arranged side by side over almost the entire length of both side surfaces of the steel pipe 1. A sheet pile joint member (corresponding to a joint) 3 with a steel pipe sheet pile is attached by welding, respectively.

  And although not shown in a figure, the steel pipe sheet pile P is sequentially built in an installation object part so that the sheet pile coupling members 3 may fit, and partition walls, such as a retaining wall and a seawall, are laterally continued by the steel pipe sheet pile group. Can be configured. In addition, with respect to the depth direction, a predetermined length dimension can be secured by fitting and connecting the concave mechanical joint member 2A and the convex mechanical joint member 2B and adding a plurality of steel pipe sheet piles P.

  As shown in FIG. 2, the mechanical joint member 2 includes a ring-shaped concave mechanical joint member 2A provided at one end (for example, the lower end) of the steel pipe 1, and the other end (for example, the upper end) of the steel pipe 1. And a ring-shaped convex mechanical joint member 2B having a structure that can be fitted and connected to the concave mechanical joint member 2A.

  The concave mechanical joint member 2A and the convex mechanical joint member 2B are configured so as to be able to fit in a state of overlapping inside and outside in the pipe diameter direction, and each of the circumferential grooves 4, 5 is configured. A key member 6 that can be interposed between the circumferential grooves 4 and 5 is provided. By positioning the key member 6 across the circumferential grooves 4 and 5, the concave mechanical joint member 2A and the convex mechanical joint are provided. It can be in a locked state that restricts relative movement of the member 2B in the tube axis direction, and the corresponding steel pipes 1 can be connected to each other in a retaining state.

Thus, the mechanical coupling members 2 are configured to have a relatively high dimensional accuracy so that the key member 6 can be fitted over the circumferential grooves 4 and 5.
Therefore, if thermal contraction occurs due to the welding of the sheet pile joint member 3 to the steel pipe 1, the dimensional accuracy between the mechanical joint members 2 also decreases, and it may be impossible to position the key member 6 in the locked state. is there.
In order to prevent this, it is necessary to maintain the flatness of the tube end face so as not to decrease.

In the present embodiment, as shown in FIG. 3, the sheet pile joint member 3 is made of a steel material having a “C” -shaped or “T” -shaped cross section when viewed from the tube axis direction. An example is described in which the steel tube 1 is attached by welding at a position 90 degrees from the reference point K and a position 270 degrees from the reference point K as the central angle around the cylinder axis. ing. In the figure, the reference point K is based on a state where it is positioned above. However, the angle from the reference point K here is a clockwise angle around the cylinder axis from the convex mechanical joint member 2B side of the steel pipe sheet pile P to the concave mechanical joint member 2A side.
The attachment position and the number of attachment places of the sheet pile joint member 3 are not limited to this, and depending on the field situation where the steel pipe sheet pile P is used, for example, only at a position of 90 degrees (see FIG. 15 (a)). ), A position of 90 degrees and a position of 180 degrees (or 360 degrees) (see FIG. 15B), a position of 90 degrees, a position of 180 degrees, and a position of 270 degrees (FIG. 15C). It may be set at any position and any number of attachment points. Further, the central angle of the mounting position from the reference point K is not limited to the multiple of 90 such as 90 degrees, 180 degrees, and 270 degrees described above. For example, a multiple of 90 such as 80 degrees and 100 degrees. You may set to the position of arbitrary angles other than.

[First Embodiment]
When the sheet pile joint member 3 is attached by welding to both side portions (positions of 90 ° and 270 °) of the steel pipe 1 to which the mechanical joint member 2 is attached by welding at both ends, the heat of the steel material increases as the heat decreases. Shrinkage occurs, and the effect appears as a dent in the end face of the steel pipe sheet pile P.
As an example of this measurement, the end face 2a of the convex mechanical joint member 2B with a steel pipe sheet pile P having a diameter of 1000 mm, a wall thickness of 12 mm, and a length of 5000 mm, as shown in FIG. 4, from the virtual reference plane H for measurement to the joint member end face 2a. The separation dimension S up to was determined. The values are as shown in FIG.
Further, the sheet pile joint member 3 uses a steel material having a “C” cross-sectional shape at both locations.
According to this result, in the vicinity of the circumferential range to which the sheet pile joint member 3 is attached, that is, in the vicinity of the 90-degree position and the 270-degree position, the dent appears larger than the other circumferential ranges. At a position of 270 degrees, a maximum value of 0.77 mm is observed. Since the maximum value of the separation dimension S between the virtual reference plane H and the joint member end surface 2a corresponds to the flatness, the flatness Smax is 0.77 mm in this example.

The method of correcting the flatness of the end face of the steel pipe sheet pile P according to the first embodiment is the end part (the other end part of the steel pipe sheet pile, etc.) to which the convex mechanical joint member 2B of the steel pipe sheet pile P is fixed. As shown in FIG. 3 and FIG. 4, at least a part of the entire circumference of the steel pipe 1 where the sheet pile joint member 3 is not provided is heated with a gas flame, thereby causing a temperature drop after heating. The shrinkage | contraction of this was raised and the method of improving the flatness of the end surface of the other end part of the steel pipe sheet pile P was taken.
Specifically, at a position of 821 mm from the other end of the steel pipe sheet pile P, a position of 196 mm (steel pipe length) centering on the position of 0 degrees and the position of 180 degrees from the reference point K in the entire peripheral surface of the steel pipe 1. A heating area E of (direction range) × 314 mm (steel pipe circumferential direction range) was set (see FIG. 6) and heated at a temperature of 700 ° C. over 5 minutes. That is, the center of the heating area E is set at the center between the positions where the two sheet pile joint members 3 are attached in the circumferential direction of the steel pipe sheet pile P.
More specifically, the heating point in the heating area E of 196 mm (steel pipe length direction range) × 314 mm (steel pipe circumferential direction range) is set to 15 points in 3 rows and 5 columns at an equal pitch, as shown in FIG. The three points in one row were heated for a total of 1 minute, moved sequentially to the next row, and heated for a total of 5 minutes.
Moreover, regarding the heating temperature of 700 ° C., the mechanical properties as the material of the steel pipe 1 (for example, SKY400, SKY490, etc.) are set to the upper limit side in a range that does not change before and after heating. The heating position is set in the range of the steel pipe end side (the other end side of the steel pipe sheet pile) from the central part in the longitudinal direction of the steel pipe 1.

By performing the flatness correction method described above, the flatness of the end face of the steel pipe sheet pile P is improved as shown in FIG.
That is, the maximum value of the separation dimension S seen at a position of 270 degrees is 0.48 mm, and the flatness Smax is corrected from 0.77 mm to 0.48 mm.
As a result of this correction, the mechanical joint members 2 can be fitted together and switched to the locked state by the key member 6, and the steel pipe sheet piles P can be connected to each other.

[Second Embodiment]
Descriptions that are common to the first embodiment described above are omitted, and different items are mainly described.
In this embodiment, a steel pipe sheet pile having a length of 12000 mm is used.
Further, the sheet pile joint member 3 uses a steel material having a “C” cross-sectional shape at both locations.
At the time when the welding of the sheet pile joint member 3 is completed, as in the first embodiment, in the vicinity of the position of 90 degrees from the reference point K and the position of 270 degrees, there is a dent on the end face more than the other circumferential ranges. It appears greatly.

The method for correcting the flatness of the end face of the steel pipe sheet pile P is the one in which the convex mechanical joint member 2B of the steel pipe sheet pile P is fixed and the concave mechanical joint member 2A is fixed. As shown in FIGS. 3 and 4, at both the end portion (one end portion), at least a part of the entire circumference of the steel pipe 1 where the sheet pile joint member 3 is not provided is heated by a gas flame. Thus, a method was adopted in which the shrinkage of the material accompanying the temperature drop after heating was caused to improve the flatness of the end faces of both ends of the steel pipe sheet pile P.
Specifically, on the convex mechanical joint member 2B side of the steel pipe sheet pile P, at a position of 815 mm from the end portion, a position of 0 degrees from the reference point K and a position of 180 degrees of the entire circumferential surface of the steel pipe 1 are set. A heating area E of 154 mm (steel pipe length direction range) × 314 mm (steel pipe circumferential direction range) was set as the center (see FIG. 9) and heated at a temperature of 700 ° C. for 5 minutes.
Moreover, on the concave mechanical joint member 2A side of the steel pipe sheet pile P, the position of 0 degrees from the reference point K and the position of 180 degrees are centered in the entire circumferential surface of the steel pipe 1 at a position of 759 mm from the end. The heating area E of 157 mm (steel pipe length direction range) × 314 mm (steel pipe circumferential direction range) was set (see FIG. 9), and heated at a temperature of 700 ° C. for 5 minutes.

By performing the above flatness correction method, the flatness of the end face of the steel pipe sheet pile P is improved as shown in FIG. 7 on the convex mechanical joint member 2B side and FIG. 8 on the concave mechanical joint member 2A side. Yes.
That is, on the convex mechanical joint member 2B side of the steel pipe sheet pile P, the flatness Smax is corrected from 1.05 mm to 0.65 mm, and on the concave mechanical joint member 2A side of the steel pipe sheet pile P, the flatness Smax is 1. It is corrected from 02mm to 0.65mm.
As a result of this correction, the mechanical joint members 2 can be fitted together and switched to the locked state by the key member 6, and the steel pipe sheet piles P can be connected to each other.

[Third Embodiment]
Descriptions that are common to the first embodiment described above are omitted, and different items are mainly described.
In this embodiment, a steel pipe sheet pile having a length of 12000 mm is used.
Moreover, the sheet pile joint member 3 uses a steel material having a “C” -shaped cross section in one of the two locations, and a steel material having a “T” -shaped cross section in the other.
At the time when the welding of the sheet pile joint member 3 is completed, as in the first embodiment, in the vicinity of the position of 90 degrees from the reference point K and the position of 270 degrees, the dent of the end surface is larger than the other circumferential ranges. Appears.

The method for correcting the flatness of the end face of the steel pipe sheet pile P is the one in which the convex mechanical joint member 2B of the steel pipe sheet pile P is fixed and the concave mechanical joint member 2A is fixed. As shown in FIGS. 3 and 4, at both the end portion (one end portion), at least a part of the entire circumference of the steel pipe 1 where the sheet pile joint member 3 is not provided is heated by a gas flame. Thus, a method was adopted in which the shrinkage of the material accompanying the temperature drop after heating was caused to improve the flatness of the end faces of both ends of the steel pipe sheet pile P. However, with respect to the concave mechanical joint member 2 </ b> A side of the steel pipe sheet pile P, heating areas are set at two places spaced in the longitudinal direction of the steel pipe sheet pile P.
Specifically, the convex mechanical joint member 2B side of the steel pipe sheet pile P has a position of 0 degrees from the reference point K and a position of 180 degrees in the entire circumferential surface of the steel pipe 1 at a position of 715 mm from the end. A heating area E of 190 mm (steel pipe length direction range) × 314 mm (steel pipe circumferential direction range) was set as the center (see FIG. 12) and heated at a temperature of 700 ° C. for 5 minutes.
Further, the concave mechanical joint member 2A side of the steel pipe sheet pile P is located at a position of 715 mm from the end, and at a position of 1630 mm from the end, at a position of 0 degree from the reference point K in the entire circumferential surface of the steel pipe 1; The heating area E was set around the position of 180 degrees (see FIG. 12) and heated at a temperature of 700 ° C. for 5 minutes. The heating area E close to the end is set to a range of 190 mm (steel pipe length direction range) x 314 mm (steel pipe circumferential direction range), and the heating area E far from the end is 180 mm (steel pipe length direction range) x 314 mm (steel pipe) (Range in the circumferential direction) is set.
Moreover, the heating order of each heating area E starts from the heating area E on the convex mechanical joint member 2B side of the steel pipe sheet pile P, from the heating area E near the end part on the concave mechanical joint member 2A side of the steel pipe sheet pile P, and the end part. It was carried out in the order of distant heating area E.

By implementing the above flatness correction method, the flatness of the end surface of the steel pipe sheet pile P is improved as shown in FIGS.
That is, after heating in the three heating areas E, the flatness Smax is corrected from 1.22 mm to 0.79 mm on the convex mechanical joint member 2B side of the steel pipe sheet pile P, and the concave mechanical joint of the steel pipe sheet pile P is obtained. On the member 2A side, the flatness Smax is corrected from 1.09 mm to 0.68 mm.
In the drawing, the heating at the two ends of the heating area E on the convex mechanical joint member 2B side and the heating area E closer to the end on the concave mechanical joint member 2A side is completed. It also describes the flatness. The flatness Smax at this time is 0.81 mm on the convex mechanical joint member 2B side and 0.76 mm on the concave mechanical joint member 2A side.
According to this result, it is understood that the heating effect in the heating area E far from the end on the concave mechanical joint member 2A side is also reflected on the convex mechanical joint member 2B side.
As a result of these corrections, the mechanical joint members 2 can be fitted together and switched to the locked state by the key member 6, and the steel pipe sheet piles P can be connected to each other.

[Another embodiment]
Other embodiments will be described below.

<1> The steel pipe sheet pile P is not limited to the dimensions and shapes described in the previous embodiment, and general steel pipe sheet piles are targeted.
For example, it is not restricted to the steel pipe sheet pile P which provided the mechanical coupling member 2 in both ends, For example, the structure which can use the edge part of the steel pipe 1 as a welding joint as it is without providing the mechanical coupling member 2 may be sufficient.
Further, as shown in FIG. 13, the sheet pile joint member 3 is a steel material having a “C” -shaped cross section (see FIGS. 13 (a) and 13 (b)), and has a “T” -shaped cross section. Shaped steel materials (see FIG. 13 (b) and FIG. 13 (c)), those using two steel materials having a cross-sectional shape of “L” shape (see FIG. 13 (c)), and combinations thereof It may be.
However, as the shape of the sheet pile joint member 3 is different, a difference occurs in the amount of welding used for welding with the steel pipe 1, so that a difference occurs in the amount of heat input to the welded portion. The “C” -shaped joint member has the largest heat input, the next is the “L” -shaped joint member, and the “T” -shaped joint member has the smallest heat input.
As a result, there is a difference in the amount of heat shrinkage, and there is a possibility that the degree of decrease in flatness may be different, and in implementing flatness correction, it is necessary to deal with these difference in conditions.
In particular, as shown in FIG. 14, when the sheet pile joint members 3 having different shapes are mixed in one steel pipe sheet pile P, the center position (reference position) in the circumferential direction of the steel pipe 1 is set in setting the heating area E. Is equivalent to the sheet pile joint member 3 side with a small amount of heat input. This is because the amount of contraction (in the tube axis direction) of the steel pipe sheet pile P at the position where the sheet pile joint member 3 is attached increases as the amount of heat input increases.
That is, in order to correct the flatness by heating, in order to perform more efficiently, it is important to heat-shrink around an area where the protruding amount of the end surface in the tube axis direction is large (an area where the shrinkage is small). Therefore, it is preferable to set the area as the heating area E. Therefore, in the steel pipe sheet pile P to which the two sheet pile joint members 3 having different heat inputs as shown in FIG. 14 are fixed, the center position between the two sheet pile joint members 3 (corresponding to the circumferential position furthest away from the joint). Since an area with a small amount of shrinkage is distributed at a location near the side where the sheet pile joint member 3 with a small amount of heat input is attached, it is preferable to set the area as the heating area E.
It is also preferable to finely adjust the position according to the difference in heat input.

<2> Moreover, the attachment position and the number of attachment locations of the sheet pile joint member 3 in the steel pipe sheet pile P can also be changed arbitrarily.
FIG. 15 illustrates the relationship between the position of the sheet pile joint member 3 and the heating area E.

<3> The setting of the heating area E for correcting the end face flatness of the steel pipe sheet pile P is not limited to the other end side of the steel pipe sheet pile P described in the previous embodiment. It may be implemented.
Furthermore, the heating area E is not limited to being set on the outer peripheral surface of the steel pipe 1 but may be set on the inner peripheral surface of the steel pipe 1.
Moreover, it is not limited to the dimension setting of the heating area E and what was demonstrated by previous embodiment.
The shape of the heating area E is not limited to the shape elongated in the pipe circumferential direction described in the previous embodiment, and for example, as shown in FIG. As shown in FIG. 16 (b), the pipe end may be larger in the pipe circumferential direction.
Moreover, when the steel pipe 1 is comprised with the spiral steel pipe, as shown in FIG.16 (c), you may set the elongate shape along a spiral weld line.
Moreover, as shown to Fig.17 (a), the rectangular heating area E in which a diagonal direction cross | intersects a pipe axis direction may be sufficient.
Moreover, the heating area E may be provided in a plurality of locations in the tube circumferential direction, or may be provided in a plurality of locations in the tube axis direction as shown in FIG.
In short, what is necessary is just to heat at least a part of the circumferential range in which the sheet pile joint member 3 is not provided in the entire circumference of the steel pipe 1.
<4> For the heating area E, the following numerical limits can be set.
In the range from the end face of the steel pipe sheet pile P to the heating area E, a value within 3 times the outer diameter of the steel pipe 1 can be cited as a value that can be expected to contribute to flatness correction by heating. More preferably, a numerical value within twice the outer diameter of the steel pipe 1 is mentioned. On the other hand, as a value that does not adversely affect the distortion caused by heating, a numerical value of 30 mm or more from the end face of the steel pipe sheet pile P can be given. More preferably, the numerical value is 150 mm or more.
As for the length in the tube circumferential direction, a value that can be expected to contribute to flatness correction by heating is a numerical value of 20 degrees or more in the central angle around the tube axis. More preferably, a numerical value of 30 degrees or more in the central angle is mentioned. On the other hand, as a value which does not give thermal deformation to the sheet pile joint member 3, a numerical value of 85 degrees or less is given as a central angle around the tube axis. More preferably, a numerical value of 80 degrees or less in terms of the central angle is used.
As for the length in the tube axis direction, a value that can be expected to contribute to flatness correction by heating is a numerical value of 80 mm or more. More preferably, the numerical value is 100 mm or more. On the other hand, a numerical value of 500 mm or less can be cited as a value that can ensure good heating workability. More preferably, the numerical value is 300 mm or less.
As the area of the heating area E, a value that can be expected to contribute to flatness correction by heating is a numerical value of 5000 mm 2 or more. More preferably, a numerical value of 25000 mm 2 or more is used. On the other hand, a value that can ensure good heating workability includes a value of 3000000 mm 2 or less. More preferably, a numerical value of 2500000 mm 2 or less is used.

  In addition, as mentioned above, although the code | symbol was written in order to make contrast with drawing convenient, this invention is not limited to the structure of an accompanying drawing by this entry. In addition, it goes without saying that the present invention can be carried out in various modes without departing from the gist of the present invention.

1 Steel pipe 3 Sheet pile joint member (equivalent to joint)
P Steel pipe sheet pile

Claims (4)

A flatness correction method for correcting the flatness of the end face of the steel pipe sheet pile for a steel pipe sheet pile in which a joint with an adjacent pipe is welded along the longitudinal direction on the outer peripheral surface of the steel pipe,
Heating at least a part of the circumferential range where the joint is not provided in the entire circumference of the steel pipe causes the material to shrink due to a temperature drop after heating, and the flatness of the end face of the steel pipe sheet pile To improve flatness.   2. The flatness correction method according to claim 1, wherein the heating position of the steel pipe is set in a range closer to a steel pipe end part to be flattened than a center part in a longitudinal direction of the steel pipe within the circumferential range.   The heating position in the circumferential direction of the steel pipe is a circumferential position furthest away from the joint, and the joint is provided at a plurality of locations in the circumferential direction of the steel pipe, and the joint adjacent in the circumferential direction. 3. The flatness correction method according to claim 1, wherein when the heat input amount of welding is different, the reference position is corrected to the joint side having a small heat input amount according to the heat input amount of welding of both joints.   The flatness correction method according to any one of claims 1 to 3, wherein the heating temperature of the steel pipe is set to an upper limit side in a range where the mechanical properties of the material of the steel pipe do not change before and after heating.

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