JP2002174362A - Contracting method and contracting jig of rolled steel pipe, and extending method and extending jig of rolled steel pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contracting method and the like for a rolled steel pipe facilitating the diameter change of contraction or extension of the rolled steel pipe. SOLUTION: This contracting method comprises a contracting jig arrangement process for arranging a contracting jig 10 having a receiving part 12 with a width larger than the contracted outer diameter of the rolled steel pipe 1 for receiving the rolled pipe 1 from above and a retaining part 11 arranged under the receiving part 12 and having a narrow width substantially corresponding to the contracted outer diameter of the rolled steel pipe 1; a rolled steel pipe arrangement process for arranging the rolled steel pipe 1 above the contracting jig 10; and a dropping process for successively dropping the rolled steel pipe 1 to the receiving part 12 and retaining part 11 from above the contracting jig 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing the diameter of a rolled steel pipe, a method for expanding the rolled steel pipe, and a method for rolling the rolled steel pipe which can be easily changed. And a jig for expanding a rolled steel pipe.

[0002]

2. Description of the Related Art Conventionally, a coiled steel pipe method has been used as one of the methods for updating various pipes such as water pipes buried underground. In this rolled steel pipe method, the diameter of the steel pipe is reduced (hereinafter referred to as “reduced pipe”) by overlapping the sides of the steel pipe with each other, and the steel pipe in this state is inserted into an existing pipe underground. In this method, a new pipe is installed inside an existing pipe by enlarging the pipe diameter of the steel pipe inside the pipe (hereinafter, expanding) and fixing the sides thereof.

[0003] This winding method will be described in more detail. First, a method for forming a rolled steel pipe will be described. FIG.
FIG. 4 is a conceptual diagram for explaining a conventional step of forming a rolled steel pipe. First, as shown in FIG. 14A, a predetermined square steel plate 100 is formed by cutting a roll steel plate (not shown), and as shown in FIG. According to 101, the end is bent to a predetermined radius. Then, as shown in FIG. 14 (c), the steel plate 100 after this processing is formed into a predetermined pipe diameter by a roll forming machine 102 to form a rolled steel pipe 103. Thereafter, as shown in FIG. 14D, the rolled steel pipe 103 was contracted to a predetermined diameter, and the rolled steel pipe 103 was fixed in this state.

[0004] Next, a method of installing the rolled steel pipe 103 will be described. FIG. 15 is a conceptual diagram for explaining a process of installing the conventional rolled steel pipe 103. As shown in FIG. 15, a vertical shaft 111 is provided beside the existing pipe 110 buried underground.
Drilling. And from this shaft 111, the steel pipe 10
3 is lowered and inserted into the existing pipe 110. At this time, the wound steel pipe 103 is contracted so that its outer diameter is smaller than the inner diameter of the existing pipe 110 and has an outer diameter that allows for a work space required at the time of insertion. It can be smoothly inserted into the existing pipe 110. That is, when using a rolled steel pipe, there is an advantage that the length of the passage pipe can be set longer than when using a normal steel pipe.

[0005] Thereafter, the wound steel pipe 103 is expanded, and centering is performed in the pipe axis direction and the circumferential direction. Then, rolled steel pipe 1
In addition to performing the seam welding in the tube axis direction of No. 03, the welding is performed on another wound steel pipe 103 already arranged on the side. After that, the mortar made in the mortar plant 112 on the ground is transported by the pump 113, and the mortar is poured between the existing pipe 110 and the coiled steel pipe 103,
These two tubes are fixed to each other. With this, rolled steel pipe 103
Is completed. According to such a method, it is not necessary to remove the existing pipe 110, and it is not necessary to perform excavation in a wide area, so that a new pipe can be newly constructed in a relatively short period of time and at low cost.

[0006] Now, in such a wound steel pipe construction method, a pipe diameter changing operation which is a characteristic step, that is,
It is extremely important to efficiently reduce and expand the coiled steel pipe 103. Hereinafter, a conventional method of contracting and expanding the rolled steel pipe 103 will be described. FIG. 16 is a conceptual diagram showing a conventional contraction and expansion method.

First, in order to perform the contraction, the rolled steel pipe 1 is used.
Inward pressure was applied to lever 03 by lever block 114. Specifically, as shown in FIG.
The lever block 114 is arranged inside the rolled steel pipe 103 and both ends are fixed inside the rolled steel pipe 103. Then, the rolled steel pipe 103 was contracted by gradually pulling both ends thereof by the lever block 114. In addition, a wire or the like is hung on the outside of the rolled steel pipe 103 without being limited to the inside,
A method of contracting the rolled steel pipe 103 by gradually narrowing it down at 14 has also been adopted.

On the other hand, in order to expand the pipe, the steel pipe 1
An outward pressure was applied to the lever 03 by the lever block 114. Specifically, as shown in FIG.
Lever block 114 arranged inside coiled steel pipe 103
To gradually expand both ends of the steel pipe 1
Pressure was applied from the inside to the outside of 03.

[0009]

However, in such a method for contracting and expanding the rolled steel pipe 103, it is necessary to fix the lever block 114, the wire and the like to the rolled steel pipe 103. However, there is a problem that a large amount of time and labor is required for the contraction and expansion of the tube, and the efficiency of the entire winding method is reduced. Therefore, there has been a long-felt need for a method of contracting and expanding the wound steel pipe 103 which can be easily performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a method of contracting a rolled steel pipe and a method of expanding the rolled steel pipe, which can easily change the diameter of the rolled steel pipe such as contraction or expansion. It is an object of the present invention to provide a jig for reducing a rolled steel pipe and a jig for expanding a rolled steel pipe used in each of these methods.

[0011]

SUMMARY OF THE INVENTION In order to solve the problems in the above conventional contraction method, the contraction method according to the first aspect is a contraction method for reducing the diameter of a rolled steel pipe. The above-mentioned rolled steel pipe is received from above,
A receiving portion having a width wider than the outer diameter of the wound steel pipe after contraction, which is disposed below the receiving portion,
A constricting jig arranging step of disposing a constricting jig including a holding portion having a narrow width substantially corresponding to an outer diameter of the convoluted steel pipe after the constricting; And a dropping step of sequentially dropping the rolled steel pipe into the receiving portion and the holding portion thereof from above the contraction jig.

According to this method, simply by dropping the rolled steel pipe into the contraction jig, the rolled steel pipe is gradually contracted while moving downward by its own weight, and can be automatically contracted. , And the work of contracting the pipe is extremely easy.

According to a second aspect of the present invention, in the first aspect of the present invention, in the step of arranging the rolled steel pipe, the overlap of the rolled steel pipe is set to a lower side of the rolled steel pipe. And in the dropping step, the rolled steel pipe is dropped with the overlap margin at the top.

According to this method, while the rolled steel pipe is held by the holding portion, the overlapping margin is pressed and fixed by the weight of the rolled steel pipe, so that the work of fixing the rolled steel pipe is further improved. It can be done easily.

[0015] The present invention also relates to a contraction jig according to claim 3, which is a contraction jig for reducing the diameter of a rolled steel pipe. A receiving part having a width wider than an outer diameter of the wound steel pipe after the contraction, and a receiving part disposed below the receiving part, wherein the compressed steel pipe is compressed. A holding portion having a narrow width substantially corresponding to the outer diameter after the pipe.

According to this jig, the steel pipe can be automatically contracted by moving the steel pipe downward by its own weight only by dropping the steel pipe from above. Contraction work is extremely easy.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the inner surface of the holding portion is formed by:
It is characterized in that the rolled steel pipe is formed in a curved shape substantially corresponding to the outer shape after contraction.

According to this jig, the rolled steel pipe after the contraction comes into contact with the holding portion in a wide range and is most stably held by the holding portion, so that the operation of fixing and the like can be performed more easily. be able to.

According to a fifth aspect of the present invention, there is provided a contraction jig according to the third or fourth aspect, wherein the rolled steel pipe is slid in an inner surface of the holding portion in the direction of the contraction. It is characterized by having a sliding part.

According to this jig, the wrapped steel pipe can be slid in the direction of its contraction by the sliding portion, so that the wrapped steel pipe can be contracted more smoothly and the working efficiency can be improved. it can.

[0021] The present invention also relates to a method for expanding a pipe, and a method for expanding the pipe according to a sixth aspect of the present invention is a method for expanding the diameter of a rolled steel pipe. An expansion jig arranging step of arranging an expansion jig having a narrow width equal to or less than the inner diameter inside the rolled steel pipe, and while the expansion jig is in contact with an upper inner surface of the rolled steel pipe, And a pipe expanding jig moving step of moving the pipe.

According to this method, it is possible to automatically expand the rolled steel pipe simply by disposing the pipe expanding jig inside the rolled steel pipe and moving it upward, and the pipe expanding operation is extremely easy. .

Further, the present invention relates to an expansion jig, and an expansion jig according to claim 7 is an expansion jig for enlarging the pipe diameter of a rolled steel pipe, wherein It is characterized in that it is provided with a contact portion that is formed to have a narrow width equal to or less than the inner diameter before expansion and is capable of contacting the upper inner surface of the wound steel pipe.

According to this jig, the rolled steel pipe can be automatically expanded simply by disposing the pipe expansion jig inside the rolled steel pipe and moving it upward, and the pipe expansion work is extremely easy. It is.

[0025] In the pipe expanding jig according to claim 8, in the pipe expanding jig according to claim 7, the abutting portion includes a contact portion with the rolled steel pipe after the pipe expansion of the rolled steel pipe. It is characterized by being arranged so as to substantially correspond to a perfect circle of the inner diameter.

According to this jig, when the rolled steel pipe is lifted through the contact portion, the rolled steel pipe is supported via the contact portion so as to expand in a perfect circular shape, and the rolled steel pipe is supported. It is possible to expand the filled steel pipe into an ideal perfect circular shape.

The pipe expanding jig according to claim 9 is the pipe expanding jig according to claim 7 or 8, wherein the abutting portion has a sliding portion for sliding the rolled steel pipe in the pipe expanding direction. It is characterized by having.

According to this jig, the wrapped steel pipe can be slid in the expanding direction by the sliding portion, so that the wrapped steel pipe can be expanded more smoothly and the working efficiency can be improved.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 of the present invention will be described below.
2 will be described in detail with reference to the drawings. The present invention is not limited by the embodiment. In particular,
According to the tube contraction method and the tube expansion method of the present invention, the inner diameter D of the wound steel pipe in the expanded state is about 4500 mm, and the wall thickness t is about 18 to 2 mm.
It is most suitable for a large-diameter rolled steel pipe having a diameter of 1 mm and a D / t ratio of about 200 to 250, but is not limited to such a rolled steel pipe and can be applied to any rolled steel pipe. Things.

(Embodiment 1) First, Embodiment 1 relating to a method and a jig for contracting a tube will be described. FIG.
FIG. 2 is a perspective view showing a rolled steel pipe and a contraction jig before contraction. FIG. 2 is a perspective view showing a rolled steel pipe and a contraction jig after contraction.
FIG. 3 is a side view of the contraction jig. The tube reducing method according to the present embodiment is generally performed by dropping a rolled steel pipe into a narrowing jig having a wide width to a narrow width, thereby reducing the diameter of the rolled steel pipe by its own weight. It is a method of performing.

First, the wound steel pipe and the contraction jig will be sequentially described with reference to FIGS. The rolled steel pipe 1 can be formed in accordance with the above-described conventional forming method except for the contraction step. That is, a rolled steel plate or the like can be cut to form a steel plate, the steel plate can be bent at an end, and further formed into a predetermined pipe diameter by a roll forming machine. In the state after the formation, the side of the rolled steel pipe 1 is provided with the structure shown in FIG.
As shown in FIG. FIG.
2 is D1 and the inside diameter of the wound steel pipe 1 after the contraction shown in FIG. 2 is D2.

Also, as shown in FIGS.
0 is formed in a horizontally long shape substantially corresponding to the rolled steel pipe 1, and is schematically illustrated as a holding portion 11, a receiving portion 12, and
A plurality of support legs 13 are provided. The holding section 11 cooperates with the receiving section 12 to contract the rolled steel pipe 1 and further holds the rolled steel pipe 1 after the contraction in a contracted state. Specifically, the holding portion 11 is formed in a horizontally long semicylindrical shape as a whole, and is arranged with its opening side facing upward.
As shown in FIG. 3, the holding portion 11 is formed such that the inner width L1 of the opening is a narrow width (L1 ≒ D2) substantially corresponding to the outer diameter of the wound steel pipe 1 after the contraction. This prevents expansion of the wound steel pipe 1 after the contraction.

In particular, in the present embodiment, the holding portion 11
Is formed in a shape substantially corresponding to the wound steel pipe 1 after the contraction. That is, the inner surface 11a of the holding portion 11 is formed into a curved surface (semi-cylindrical surface) substantially corresponding to the outer diameter of the wound steel pipe 1 after the contraction. Therefore, the rolled steel pipe 1 after the contraction comes into contact with the holding portion 11 in a wide range and is most stably held by the holding portion 11, so that the fixing and the like can be performed more easily. However, when it is not necessary to consider such an effect, the holding unit 11 does not necessarily need to be formed in a semi-cylindrical shape, and may be formed in, for example, a V-shape.

The receiving section 12 cooperates with the holding section 11 to contract the rolled steel pipe 1, receives the rolled steel pipe 1 before the pipe is reduced from above, and further receives the rolled steel pipe 1. Is transferred to the holding unit 11. Specifically, as shown in FIGS. 1 and 2, the receiving portion 12 is formed from a plurality of rods, extends from the upper end of the holding portion 11, and is arranged so as to extend upward and outward. . The receiving portion 12 has an inner width L at an upper end thereof as shown in FIG.
2 has a wide shape (L2> or more) whose outer diameter is equal to or greater than the outer diameter of the wound steel pipe 1 after contraction
D2). More specifically, the rolled steel pipe 1 before contraction is deformed by its own weight into a vertically elongated elliptical side surface in a suspended state. It is formed to have a width not less than the outer diameter of 1. Thereby, the rolled steel pipe 1 before contraction can be received from above.

The receiving portion 12 has the same narrow width L1 as the holding portion 11 at the lower end thereof, so that the wound steel pipe 1 can be smoothly transferred to the holding portion 11. In particular, in the present embodiment, the receiving unit 12
Since it is formed in an inclined shape that continuously extends from the wide width L2 to the narrow width L1, it is possible to extremely smoothly transfer the wound steel pipe 1 to the holding part 11 while contracting the pipe. However, the receiving portion 12 does not necessarily need to be formed in an inclined shape, and may be formed in a stepped shape, for example.

The holding section 11 and the receiving section 12
Are fixed to each other by any method such as welding. However, the holding portion 11 and the receiving portion 12 are
Can be arranged separately from each other in a range where the delivery is possible. However, in the present embodiment, as shown in FIG. 3, the holding portion 11 and the receiving portion 12 are connected such that the inner surfaces 11a and 12a thereof are flush with each other, whereby Inclined surface is formed. Therefore, it is possible to transfer the rolled steel pipe 1 from the holding part 11 to the receiving part 12 most smoothly.

The supporting leg 13 is a supporting structure for supporting the holding portion 11 and the receiving portion 12 and the rolled steel pipe 1 dropped into the contraction jig 10. Specifically, the support leg 13 is fixed to the side of the holding part 11 by welding or the like, and is arranged so as to extend from this side and reach a lower installation surface. However, the support leg 13 can be configured with any structure as long as it can function as a support structure.

Next, a method of contracting a pipe will be described. First,
As shown in FIG. 1, at an arbitrary contraction position such as in a plant,
The contraction jig 10 is arranged (a contraction jig arrangement step). Then, as shown in FIG. 1, the rolled steel pipe 1 is disposed above the contraction jig 10 (rolled steel pipe arrangement step). Here, the wire 14 is connected to the upper ends of both ends of the contraction jig 10 in the longitudinal direction,
The wound steel pipe 1 is hoisted by winding up the wire 14 with a crane (not shown). However, the method of arranging the rolled steel pipe 1 is arbitrary. For example, a fork of a fork wrist may be inserted into the rolled steel pipe 1 to lift the rolled steel pipe 1. In addition, this rolled steel pipe 1
Is preferably arranged such that the overlapping margin 2 is located below the rolled steel pipe 1 (the reason will be described later). In addition, as a matter of course, the wound steel pipe 1 is arranged such that the pipe axis direction coincides with the longitudinal direction of the contraction jig 10.

Thereafter, the wound steel pipe 1 is sequentially dropped into the receiving portion 12 and the holding portion 11 from above the contraction jig 10 (dropping step). Specifically, the contraction jig 10
The steel tube 1 is hung down inside the receiving part 12 by winding down the wire 14 connected to the crane with a crane. Then, the wound steel pipe 1 receives a downward force due to its own weight, and at the same time, its side surface is pressed by the receiving portion 12 to receive an inward force. As a result, the wound steel pipe 1 is gradually contracted while moving downward, and as shown in FIG. Held in state. And
The wound steel pipe 1 in this state can be fixed by any method and transported to the next step. According to such a method, it is possible to automatically contract the tube simply by dropping the wound steel pipe 1 into the contraction jig 10, and the contraction work is extremely easy.

In particular, when the rolled steel pipe 1 is dropped as described above, it is preferable to drop the steel pipe 1 with the overlapping margin 2 at the top. In other words, the rolled steel pipe 1 can be contracted even when it is dropped in a state where the overlap margin 2 is disposed on the upper side. Is located above, and the overlap margin 2 is not pressed by the weight of the rolled steel pipe 1, so that it becomes unstable and difficult to fix. On the other hand, if the drop is made with the overlap margin 2 at the top as described above,
In the state of being held by the holding portion 11, the overlap margin 2 is pressed and fixed by the weight of the wound steel pipe 1, so that the work of fixing the wound steel pipe 1 can be performed more easily.

Now, the method and the jig 1
0 has been described, but the present invention may be embodied in different embodiments other than the first embodiment described above within the scope of the technical idea described in the claims. . For example, the contraction jig 10 does not necessarily need to be formed in a horizontally long shape, and a plurality of short contraction jigs 20 can be used side by side as shown in the perspective view of FIG. In this case, even when the length of the coiled steel pipe 1 changes, it can be coped with by adjusting the number of juxtaposed jigs 20 and the juxtaposed interval according to the length.

Further, as shown in the perspective view of FIG. 5, a plurality of sliding portions 15 for sliding the rolled steel pipe 1 in the direction of the reduced tube may be provided on the inner surface of the holding portion 11 of the reduced tube jig 10. it can. As shown in the enlarged side view of FIG.
It is provided with a plurality of rollers 15a that rotate along the direction of contraction. Therefore, in a state where the outer surface of the rolled steel pipe 1 is in contact with the upper surface of the roller 15a, the rolled steel pipe 1 can be slid in the contraction direction. In addition, as shown in FIG. 5, it is preferable that the sliding portion 15 is uniformly dispersed in a contact portion of the inner surface of the holding portion 11 with the rolled steel pipe 1. The sliding section 15 can be provided on the inner surface of the receiving section 12, and each sliding section 15 can be provided with only one large roller.

(Second Embodiment) Next, a second embodiment relating to a pipe expansion method and a pipe expansion jig will be described. FIG.
Is a perspective view showing a rolled steel pipe and a pipe expansion jig before pipe expansion, FIG. 8 is a perspective view showing a state where the pipe expansion jig is inserted into the rolled steel pipe, and FIG. 9 is a rolled steel pipe and pipe expansion jig after pipe expansion. FIG. 10 is a perspective view showing a tool, and FIG. 10 is an enlarged side view of a main part in a state where a pipe expanding jig is inserted into a rolled steel pipe. The pipe expansion method in the present embodiment is a method in which, by roughly moving a pipe expansion jig inserted into the inside of a rolled steel pipe, the pipe expansion of the rolled steel pipe is performed by the pipe expansion force of the rolled steel pipe itself. It is. Note that the structure of the wound steel pipe 1 is the same as that of the first embodiment, and the description thereof is omitted.

First, the tube expanding jig 30 will be described. As shown in FIG. 7, the pipe expanding jig 30 includes a jig main body 31 framed in a substantially rectangular shape, and a contact portion 32 disposed on an upper surface of the jig main body 31. . The jig main body 31 supports the own weight of the rolled steel pipe 1 via the contact portion 32 when the pipe expanding jig 30 is inserted into the rolled steel pipe 1 and moved upward. It is a support structure.

In the present embodiment, the width W1 of the jig body 31 is formed so as to be equal to or less than the inner diameter D1 of the rolled steel pipe 1 before expanding (W1 <D2). Can be inserted into The length L1 of the jig body 31 in the longitudinal direction is substantially the same as or slightly longer than that of the rolled steel pipe 1, and at least the pipe expanding jig 30 is inserted into the rolled steel pipe 1. In this jig body 31
Can be connected to the wire 14 for lifting.

A plurality of contact portions 32 are arranged at both ends in the longitudinal direction of the jig body 31. As shown in FIG. 10, each contact portion 32 is formed in an upwardly-facing triangular pyramid shape, and can contact and support the rolled steel pipe 1 at its apex. By reducing the contact area between them as much as possible, it is possible to smoothly slide with respect to the contact portion 32 when the rolled steel pipe 1 expands.

In particular, as shown in FIG. 10, the contact portion 32 is disposed such that the apex, which is the contact portion with the rolled steel pipe 1, substantially corresponds to the perfect circle of the inner diameter of the rolled steel pipe 1 after expansion. ing. That is, the apex of the contact portion 32 is on the curve of the inner surface of the rolled steel pipe 1 in a state where the rolled steel pipe 1 is ideally expanded (in a state of being expanded in a perfect circle) (in the imaginary line in FIG. 10). Are shown at the same position and height. Therefore, when the rolled steel pipe 1 is lifted through the apex of the abutting portion 32, the rolled steel pipe 1 is supported via the apex so as to expand in an ideal perfect circle, and the rolled steel pipe 1 is supported. 1 can be expanded into an ideal perfect circular shape.

Next, a method of expanding the pipe will be described. First,
As shown in FIGS. 7 and 8, the pipe expanding jig 30 is disposed inside the rolled steel pipe 1 by inserting the pipe expanding jig 30 from the side of the rolled steel pipe 1 (a pipe expanding jig placement step). Then, as shown in FIGS. 9 and 10, the pipe expanding jig 30 is moved upward while being in contact with the upper inner surface of the rolled steel pipe 1 (tube expanding jig moving step). Specifically, the wire 14 is connected to both ends in the longitudinal direction of the pipe expanding jig 30 by an arbitrary method, and the wire 14 is hoisted by a crane (not shown), thereby lifting the pipe expanding jig 30. As a result, the rolled steel pipe 1 is lifted upward through the contact portion 32 of the pipe expansion jig 30, is supported by the contact portion 32 so as to ideally expand the pipe, and has a pipe expansion force (restoration) of its own. Force). Then, the expanded state is fixed by an arbitrary fixing tool, and the rolled steel pipe 1 can be installed at a predetermined installation location. According to such a method, it is possible to automatically expand the rolled steel pipe 1 simply by disposing the pipe expansion jig 30 inside the rolled steel pipe 1 and moving it upward, and the pipe expansion work is extremely easy. is there.

Now, the tube expansion method and tube expansion jig 3
0 has been described, but the present invention may be embodied in different embodiments other than the above-described second embodiment within the technical idea described in the claims. . For example, the contact portion 32 of the pipe expansion jig 30
Is not limited to the triangular pyramid shape as described above, and as shown in FIG. 11, the entire pipe expanding jig 40 may be formed as a curved rod-shaped body 41 along the inner surface of the wound steel pipe 1 after expanded. . Further, the pipe expanding jig 30 and the abutting portion 32 do not necessarily have to be formed in a shape along the inner surface of the rolled steel pipe 1 after the pipe expansion, and the pipe expanding jig 30 and the abutting portion 32 are of such a degree that the force in the expanding direction can be applied to the rolled steel pipe 1. It can be formed in any shape as long as it has a width.

Alternatively, when the tube expanding force of the wound steel pipe 1 itself is large, the tube expanding jig 30 may be formed to have a narrow width, for example, it may be formed as a simple rod. The pipe expanding jig 30 can be divided into a plurality of parts and arranged side by side. In this case, the left and right pipe expanding jigs 30 are lifted diagonally upward outward by separate wires. Thereby, a stronger pipe expanding force can be given. Note that the upward movement of the pipe expanding jig 30 can be performed by an arbitrary method such as lifting by a forklift, in addition to lifting by a wire.

As shown in the perspective view of FIG. 12, the contact portion 32 of the pipe expanding jig 30 may be provided with a plurality of sliding sections 33 for sliding the wound steel pipe 1 in the pipe expanding direction.
As shown in an enlarged side view of a main part in a state in which the pipe expanding jig 30 of FIG. 13 is inserted into the coiled steel pipe 1, each of the sliding parts 33 is pivotally supported at its rotation center by a contact part 32. The steel pipe 1 is rotatable along the expanding direction. Therefore, in a state where the inner surface of the rolled steel pipe 1 is in contact with the upper surface of the sliding portion 33, the rolled steel pipe 1 can be slid in the expanding direction. In addition, the sliding part 33 can also be comprised from several small rollers like the sliding part 15 of Embodiment 1.

[0052]

As described above, according to the shrinking method according to the present invention (claim 1), simply by dropping the rolled steel pipe into the shrinking jig, the rolled steel pipe is lowered by its own weight. Since the tube is gradually contracted while moving and can be automatically contracted, the tube contracting operation is extremely easy.

Further, according to the shrinking method according to the present invention (claim 2), in a state where the rolled steel pipe is held by the holding portion, the overlapping margin is pressed by the own weight of the rolled steel pipe and fixed. Therefore, the work of fixing the wound steel pipe can be performed more easily.

Further, according to the contracted pipe jig according to the present invention (claim 3), only by dropping the rolled steel pipe from above the contracted pipe jig, the rolled steel pipe is gradually moved downward by its own weight. The tube can be automatically contracted and the tube can be contracted very easily.

Further, according to the contraction jig according to the present invention (claim 4), the rolled steel pipe after the contraction comes into contact with the holding portion in a wide range, and is most stably held by the holding portion. Therefore, the work such as fixing can be performed more easily.

Further, according to the contraction jig according to the present invention (claim 5), the rolled steel pipe can be slid in the direction of the contraction by the sliding portion, so that the rolled steel pipe can be contracted more smoothly. And work efficiency can be improved.

Further, according to the pipe expanding method of the present invention (claim 6), simply by disposing the pipe expanding jig inside the rolled steel pipe and moving it upward, the rolled steel pipe is automatically expanded. And the pipe expansion work is extremely easy.

Further, according to the pipe expanding jig of the present invention (claim 7), the pipe expanding jig is automatically arranged simply by disposing the pipe expanding jig inside the coiled steel pipe and moving the pipe expanding jig upward. The pipe can be expanded, and the pipe expansion operation is extremely easy.

Further, according to the pipe expanding jig of the present invention (claim 8), when the rolled steel pipe is lifted through the contact portion, the rolled steel pipe becomes true through the contact portion. It is supported so as to expand in a circular shape, and the rolled steel pipe can be expanded in an ideal perfect circular shape.

Further, according to the pipe expanding jig according to the present invention (claim 9), the rolled steel pipe can be slid in the expanding direction by the sliding portion, so that the rolled steel pipe can be expanded more smoothly. And work efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a wound steel pipe and a jig for contracting a tube before contraction according to the first embodiment of the present invention.

FIG. 2 is a perspective view showing the rolled steel pipe and the contraction jig after the contraction according to the first embodiment;

FIG. 3 is a side view of the contraction tube jig according to the first embodiment.

FIG. 4 is a perspective view showing another example of the contraction tube jig of the first embodiment.

FIG. 5 is a perspective view showing another example of the contraction tube jig of the first embodiment.

FIG. 6 is an enlarged side view of the sliding portion of FIG. 5;

FIG. 7 is a perspective view showing a rolled steel pipe and a pipe expansion jig before pipe expansion according to a second embodiment of the present invention;

FIG. 8 is a perspective view showing a state where the pipe expanding jig according to the second embodiment is inserted into a rolled steel pipe.

FIG. 9 is a perspective view showing a wound steel pipe and a pipe expansion jig after pipe expansion according to the second embodiment;

FIG. 10 is an enlarged side view of a main part in a state where the pipe expanding jig according to the second embodiment is inserted into a rolled steel pipe.

FIG. 11 is a perspective view showing another example of the pipe expanding jig of the second embodiment.

FIG. 12 is a perspective view showing another example of the pipe expanding jig of the second embodiment.

FIG. 13 is an enlarged side view of a main part in a state where the pipe expanding jig of FIG. 12 is inserted into a rolled steel pipe.

FIG. 14 is a conceptual diagram for explaining a conventional forming process of a rolled steel pipe.

FIG. 15 is a conceptual diagram for describing a conventional installation process of a rolled steel pipe.

FIG. 16 is a conceptual diagram showing a conventional contraction and expansion method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 103 Wound steel pipe 10, 20 Contraction jig 11 Holding part 12 Receiving part 13 Support leg 14 Wire 15, 33 Sliding part 15a Roller 30, 40 Expanding jig 31 Jig main body 32 Contact part 41 Curved rod-shaped body 110 Existing pipe

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Shozo Kikuchi 12 Nishikicho, Naka-ku, Yokohama-shi Yokohama Heavy Industries, Ltd., Mitsubishi Heavy Industries, Ltd. Nippon Steel Corporation (72) Inventor Sakae Ishiyama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Toshinori Shiozaki 12 Nishikicho, Naka-ku, Yokohama-shi F term in the company (reference) 4E063 AA05 BB03 MA02

Claims (9)

[Claims] 1. A method for reducing the diameter of a rolled steel pipe, wherein the rolled steel pipe is received from above, and is wider than the outer diameter of the rolled steel pipe after the reduction. And a holding part having a narrow width substantially corresponding to the outer diameter of the wound steel pipe after the shrinking, which is disposed below the receiving part. A pipe jig arranging step, a rolled steel pipe arranging step of arranging the rolled steel pipe above the contracted pipe jig, and placing the rolled steel pipe from above the contracted pipe jig into its receiving portion and holding portion. A method for reducing a rolled steel pipe, comprising: 2. The rolled steel pipe arranging step, wherein the overlap of the rolled steel pipe is positioned below the rolled steel pipe, and in the dropping step, the rolled steel pipe is dropped with the overlap margin at the top. The method for contracting a rolled steel pipe according to claim 1, wherein: 3. A shrinking jig for reducing the diameter of a rolled steel pipe, said jig receiving said rolled steel pipe from above, wherein said jig is smaller than the outer diameter of said rolled steel pipe after shrinking. A winding part comprising: a wide receiving part; and a narrow holding part, which is disposed below the receiving part and substantially corresponds to an outer diameter of the wound steel pipe after contraction. Jig for shrinking steel pipe. 4. The jig of claim 3, wherein the inner surface of the holding portion is formed in a curved shape substantially corresponding to the outer shape of the coiled steel tube after contraction. . 5. The jig of claim 3, further comprising a sliding portion on an inner surface of the holding portion for sliding the rolled steel tube in the direction of the contraction. 6. A pipe expanding method for expanding a diameter of a rolled steel pipe, wherein a pipe expansion jig formed to have a narrow width equal to or less than an inner diameter of the rolled steel pipe before expansion is provided inside the rolled steel pipe. A pipe expanding jig disposing step, and a pipe expanding jig moving step of moving the pipe expanding jig upward while contacting the pipe expanding jig with an upper inner surface of the rolled steel pipe. Expansion method. 7. An expansion jig for enlarging the diameter of a rolled steel pipe, wherein the jig is formed to have a narrow width equal to or less than the inner diameter of the rolled steel pipe before expansion, and abuts on an upper inner surface of the rolled steel pipe. A jig for expanding a rolled steel pipe, comprising: 8. The method according to claim 7, wherein the contact portion is arranged so that a contact portion with the rolled steel pipe substantially corresponds to a perfect circle of an inner diameter of the rolled steel pipe after expansion. An expansion jig for the rolled-in steel pipe described in the above. 9. The jig for expanding a rolled steel pipe according to claim 7, wherein the contact portion is provided with a sliding portion for sliding the rolled steel pipe in a pipe expanding direction.