JP2002292425A - Manufacturing method for shape steel pipe and manufacturing device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a shape steel pipe provided with a excellent cross-sectional shape and high in symmetry of an uneven part, by suppressing the flowing of a material into a narrow gap in forming, and previously setting the optimum size of a forming roll by computation. SOLUTION: In manufacturing the shape steel pipe provided with a plurality of pairs of a recessed part and a projecting part with respect to the circumferential direction from a cylindrical raw pipe by passing through a preliminary forming stand and a finishing forming stand, a plurality of forming rolls which are disposed in the circumferential direction of the raw pipe, provided with raised parts in the total number of pieces equivalent to the number of pieces of the recessed part, and wherein parts in between the raised parts form roll roots, is formed small by the previously set amount by setting the roll dividing position on the border of one roll root of the forming roll and the raised part of adjacent forming toll, and the inter-raised part distance of the roll dividing position is made small by the previously set amount considering the inter-roll gap expanding during the forming wider than the required projecting part width to form the raw pipe by the preliminary forming stand disposed with the plurality of forming rolls in the circumferential direction of the raw pipe and the finishing stand and fix the recessed part corresponding to the recessed part to the raw pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a deformed pipe having a plurality of irregularities in a circumferential direction.

[0002]

2. Description of the Related Art Deformed pipes are used as decorative building materials in place of conventional circular pipes by utilizing the designability and discrimination derived from the shape. Examples of this type of deformed tube include a deformed tube having a plurality of uneven portions in the circumferential direction parallel to the tube axis and a deformed tube having a plurality of uneven portions formed in the circumferential direction spirally with respect to the tube axis direction. Have been. A deformed pipe having a plurality of uneven portions in the circumferential direction has been conventionally manufactured by various methods such as a drawing method using a die and a roll forming method. In the method of drawing a raw tube with a die (Japanese Patent Application Laid-Open No. 63-248515), although a deformed tube having a good cross-sectional shape is manufactured, the die needs to be changed according to the size and the shape of the deformed tube. Therefore, productivity is low.

[0003] A roll forming method for producing a deformed pipe by a rolling mill in which a grooved roll or a flat roll is combined (Japanese Patent Application Laid-Open
JP-A-142715) has high productivity, and can produce a deformed pipe having a plurality of irregularities spirally undulated in the pipe axis direction by a spiral guide or a die provided on the exit side of the rolling mill. However, the gap M between the forming rolls 1
(FIG. 1 a), and when applied to in-line molding incorporated in a pipe-making line for manufacturing a raw tube M, the unwelded portion fills the gap G of the molding roll 1. Even when the material flows in and the welded portion passes through the forming stand, the cross-sectional shape may be distorted and irregularities of a required shape may not be formed (FIG. 1b). In addition, when a spiral pattern is provided, a disadvantage is that the guide and the die are easily worn.

[0004]

When a deformed pipe having a plurality of concave and convex portions in the circumferential direction is manufactured by a roll forming method with high productivity, taking into consideration the deformation at the time of forming the unwelded portion (FIG. 1b),
A roll arrangement in which the gap G is reduced over the entire circumferential length of the raw tube M is preferable. Therefore, in the manufacture of a deformed pipe having eight sets of concave and convex portions in the circumferential direction, a forming roll 1 in which projections corresponding to concave portions are provided on the roll peripheral surface is used, and the forming roll 1 is divided by 180 degrees (FIG. 2A). Alternatively, two or four pieces are arranged in the circumferential direction of the base tube M in a 90-degree division (FIG. 2B). But,
Since the tube M has a larger diameter than the roll gap D, when the tube M is inserted into the roll gap D, a gap G is generated between the forming rolls 1. In the forming roll 1 combined in the 180-degree division (FIG. 3A) and the 90-degree division (FIG. 3B), the gap G is the protrusion p where the deformation amount of the raw tube M is the largest.
Occurs at a position corresponding to the vertex t of. Therefore, the material intensively flows into the gap G, and it becomes difficult to manufacture a deformed pipe having a required shape.

In order to improve the cross-sectional shape of the manufactured deformed pipe, it is necessary that the radius R of curvature of the convex surface of the deformed pipe P shown in FIG. 4 be uniform in the circumferential direction. In order to obtain the uniformity in the circumferential direction of the convex portion outer surface curvature radius R of the deformed tube P, it is necessary to form with the forming roll 1 having the optimum width W between the protruding portions. Heretofore, the optimum dimensions have been obtained by conducting a molding experiment using several types of forming rolls. However, there has been a problem that the roll cost is high and the efficiency is low.

The present invention has been devised in order to solve such a problem. A roll dividing position is set at a boundary between a lower portion of a certain forming roll and a raised portion of an adjacent forming roll. Cross-sectional shape collapse occurs by forming a base tube with a pre-stand and a forming stand in which a plurality of forming rolls with the protruding part interval at the roll division position determined by a predetermined formula are arranged in the circumferential direction of the base tube. An object of the present invention is to efficiently manufacture a deformed pipe having a good cross-sectional shape excellent in shape symmetry without causing the shape to be deformed.

[0007]

SUMMARY OF THE INVENTION In order to achieve the object, the present invention provides a method of manufacturing a deformed pipe having a plurality of sets of concave and convex portions in a circumferential direction from a cylindrical raw pipe. A plurality of preforming rolls which are arranged in the circumferential direction and have a total number of raised portions corresponding to the number of the concave portions, and a portion between the raised portions is a roll bottom, are adjacent to a roll bottom of a certain preformed roll. A roll dividing position is set at the boundary between the raised portions of the preforming rolls, and the width between the raised portions at the roll dividing positions is a value of the following formula (1). After preforming the base tube with a preforming stand arranged in the circumferential direction and attaching a concave portion corresponding to the concave portion to the base tube, a similar raised portion position and a raised portion at the roll dividing position set by the following formula (1) are set. Multiple rolls with the same width and arranged at similar roll division positions Characterized by forming finished mother tube target shape finish forming stand having a finish forming roll.

W2 = wa (1) where w is the required width of the convex portion of the deformed pipe, W2 is the width between the ridges of the forming roll at the roll dividing position, and a is the gap between the rolls that expands during forming. This is a value set in advance in consideration of the above. Also, when forming a raw tube with a preforming roll and a finishing forming roll in which the roll axis is inclined at a predetermined spiral angle with respect to a plane orthogonal to the tube axis of the raw tube, a spiral undulation is provided in the pipe axis direction. A modified tube is manufactured.

[0009] The deformed pipe manufacturing apparatus includes a multi-stage forming stand having at least a preforming stand and a finish forming stand. The preforming stand and the finish forming stand are formed by forming a plurality of forming rolls in which the same number of protrusions as the recesses to be formed on the raw tube are formed on the roll peripheral surface, and the bottom between the protrusions is a roll. A roll division position is set at the boundary between the roll bottom of the roll and the ridge of the adjacent forming roll, and the width between the ridges at the roll division position is
In consideration of the spread of the roll interval during forming, the spread is made smaller than the convex width of the deformed pipe which is required in advance,
The plurality of forming rolls are arranged in a circumferential direction of the raw tube. In order to manufacture a deformed pipe with a spiral undulation, the roll axis of the forming roll is inclined at a predetermined spiral angle with respect to a plane perpendicular to the pipe axis of the raw pipe.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS For manufacturing a deformed pipe according to the present invention, an apparatus in which a plurality of forming stands are arranged in tandem is used. Here, an apparatus in which two forming stands are arranged (FIG. 5).
Will be described as an example. The blank tube M is a preformed stand 1
After being preformed at 0, it is formed into a deformed pipe P having a target shape at the finish forming stand 20. Third and fourth molding stands may be further disposed between the preliminary molding stand 10 and the finish molding stand 20. Preforming stand 10
Is a combination of four preforming rolls 11 to 14 in an arrangement in which the gap G between the rolls is very narrow (FIG. 6).
a). The peripheral surface of the preforming rolls 11 to 14 has a number corresponding to the number of concaves on the peripheral surface of the target deformed pipe P (8 in the case of FIG. 6).
Ridges 11p to 14p are formed. The division position of each preforming roll 11 to 14 is
They are set at the boundaries between the roll bottoms 11b and 12b of the rolls 1 and 12 and the ridges 13p and 14p of the adjacent preforming rolls 13 and 14.

The finish forming stand 20 also has four finish forming rolls 21 to 24 arranged with a narrow gap G (FIG. 6b). Also on the peripheral surface of the forming rolls 21 to 24, the number of protrusions 21 p corresponding to the number of recesses on the peripheral surface of the target deformed pipe P is provided.
~ 24p are formed. The dividing positions of the forming rolls 21 to 24 are the same as the preforming stand 10, and the raised portions 23 p and 24 p of the finishing forming rolls 23 and 24 adjacent to the roll bottoms 21 b and 22 b of the finishing forming rolls 21 and 22.
Is set at the border with. The same roll support mechanism 30 is used for both the pre-forming stand 10 and the finish forming stand 20.
The rolls 11 to 14, 21 to 24 are rotatably supported by (FIG. 7). The roll support mechanism 30 is provided for each of the rolls 11 to 1
There is provided a roll chock 32 for rotatably supporting the roll shafts 31 of 4, 21 to 24. Roll chock 32
Is a tube M corresponding to each of the rolls 11 to 14, 21 to 24.
Are arranged in the circumferential direction, and are movable toward the center of the base tube M. By adjusting the amount of movement of the roll chock 32 by the screw 33, the amount of reduction of the raw tube M is set.

When the raw tube M is passed through the preforming stand 10 in which the preforming rolls 11 to 14 are combined as described above, the portion corresponding to the convex portion p of the deformed tube P becomes the roll bottom portion 11b.
To 14b, and the portion corresponding to the concave portion is the raised portion 1
Preformed at 1p to 14p. Preforming stand 10
When the base tube M is sent to the finish forming stand 20 from the above, the portion preformed at the roll bottoms 11b to 14b is finish-formed at the roll bottoms 21b to 24b of the finish forming rolls 21 to 24 to become the convex portion p, and the bulge is raised. The portions preformed in the portions 11p to 14p are formed by the raised portions 21p to 24p of the finish forming rolls 21 to 24 to become the concave portions b. In both the preforming and the finish forming, the preforming roll 1
A gap G is generated between 1 to 14 and the finish forming rolls 21 to 24. However, the rolls 11 to 14 and 21 to 24 are not divided at the vertex t (FIG. 3) of the convex portion p where the deformation amount of the raw tube M is the largest, and the rolling amount of the raw tube M is reduced at each stage. The gap G can be narrowed due to possible multi-stage molding. Therefore, the inflow of the material into the gap G is suppressed, and the deformed pipe P (FIG. 8) having good shape accuracy is manufactured.

This method is also effective in in-line molding in which a deformed pipe P is manufactured by incorporating it into a normal pipe production line.
That is, since the amount of reduction of the stands 10 and 20 is small, and the gap G between the rolls 11 to 14 and 21 to 24 is small, even if the plate ends e overlap in the preforming stand 10, eight sets with a small difference in elevation are set. Are provided on the tube M (FIG. 9). In the unwelded portion of the base tube M, the deformation direction of the base tube M is determined by the formation of the uneven portion, so that even if the welded portion of the base tube M reaches the preforming stand 10, it remains in the circumferential direction of the base tube M. Eight sets of irregularities will be formed. The formed concavo-convex portions are finish-formed into the concave portions b and the convex portions p by the finish forming stand 20, respectively.

The present inventors have conducted various studies on the uniformity of the outer surface radius of curvature R of the deformed pipe P in the circumferential direction. As a result, the dimensions of the forming roll shown in FIG. Considering the rigidity of the molding stand when molding into a deformed pipe P,
It has been found that the width between the ridges at the roll dividing position should be set to be smaller than the required width of the convex portion of the deformed pipe in advance by considering the spread of the roll interval during forming.

The uniformity of the outer radius of curvature R of the convex portion in the circumferential direction of the deformed pipe P shown in FIG. 4 is based on the assumption that the height of the raised portion of the forming roll 1 is higher than the maximum possible deformation height of the convex portion p. Since the amount of reduction r _T actually acting on the raw tube M is constant in the circumferential direction and the convex portion p is deformed in the region of the width W1 between the protruding portions of the forming roll 1, the width W1 between the protruding portions, It is determined by the uniformity of W2 in the circumferential direction. If the widths W1 and W2 between the ridges are uniform in the circumferential direction when forming into the deformed pipe P, the radius of curvature R of the convex surface of the manufactured deformed pipe P is also the same in the circumferential direction, and the shape symmetry is reduced. It becomes a good product.

When forming the base tube M, a gap G is formed between the forming rolls 1 due to the rigidity of the forming stand.
And the width W1 between the other raised portions needs to be different.
In other words, the width W1 between the protruding portions may be the width w of the convex portion of the deformed pipe P that is required, but the width W2 between the protruding portions at the roll dividing position is generated by the rigidity of the forming stand when the raw tube M is formed. It is necessary to set a value obtained by subtracting the gap G between the forming rolls 1 from the width w of the convex portion of the deformed pipe P that requires the gap G. The rigidity of the forming stand is determined by the deflection of the roll shaft and the gap between the bearing and the roll shaft or the roll. In general, the rigidity of the forming stand when producing steel pipes of the same size is not much different.
mm is sufficient. However, when the thickness of the pipe to be formed is increased, the force for spreading the roll is increased, so that the above-mentioned reduction value needs to be increased. Its decreasing value a
Is preferably set to the following degree as a function of the thickness t of the sheet to be formed. 0.0625t + 0.1 <a <0.0625t + 0.2 This makes it possible to efficiently and efficiently determine the roll dimensions that have been obtained by molding experiments using several types of forming rolls.

In a deformed pipe P having irregularities parallel to the pipe axis direction, the roll axis 31 is parallel to the direction orthogonal to the pipe axis of the raw pipe M.
Is used. The roll support mechanism 30 (FIG. 7) is used.
Instead of the roll support mechanism 30, a roll support mechanism 4 that inclines and supports the roll shaft 45 at a predetermined spiral angle θ in the pipe axis direction.
When 0 (FIG. 10) is used, a deformed pipe P having irregularities spirally undulating along the pipe axis direction is manufactured.

The roll support mechanism 40 is provided in the roll accommodation space 4.
1 is provided with a roll chock 43 in which the roll axis hole 42 is inclined at a helical angle θ with respect to a direction perpendicular to the tube axis of the raw tube M at a helical angle θ with respect to the tube axis direction of the raw tube M. Roll 1
The collar 44 is interposed between the roll chock 43 and the rolls 11 to 1.
4, 21 to 24 are positioned. Rolls 11 to 14, 2
By supporting the roll shafts 45 of 1 to 24 with the roll chock 43, the rolls 11 to 14, 21
24 are pressed at the spiral angle θ, and the deformed pipe P in which the convex portion p and the concave portion b are undulated at the spiral angle θ is manufactured. In addition,
Incorporating the roll support mechanism 40 into the pipe making line,
Is formed, the preforming stand 10 and the finish forming stand 20 are rotated in the circumferential direction of the raw tube M.

Although the production of the deformed pipe P having eight sets of irregularities has been described above, the present invention is not limited to this. The same applies to: The helical angle θ is preferably set to 45 degrees or less because an excessively large hindrance will hinder the rotation of the rolls 11 to 14 and 21 to 24 and the running of the raw pipe M or the deformed pipe P. Further, in each of the forming stands 10 and 20, three or five or more forming rolls can be incorporated in place of the four rolls 11 to 14, 21 to 24.

[0020]

Embodiment 1 Steel pipe ST having an outer diameter of 54 mm and a thickness of 1.6 mm
Using KM13B as a raw tube, a deformed tube having an outer diameter of 50.4 mm and having eight sets of concave and convex portions in the circumferential direction was formed in-line during raw tube production. The forming device (FIG. 5) arranged in the pipe making line has a two-stage forming stand structure, and the stands 10, 20 are formed with forming rolls 11, 12, 21 and 22, respectively.
Forming roll 1 adjacent to roll bottoms 11b and 12b
Raised portions 13p, 14p and 2 of 3, 14 and 23, 24
Roll division positions were set at the boundaries between 3p and 24p, and rolls 11 to 14, 21 to 24 having a total of eight raised portions 11p to 14p and 21p to 24p were used. In order to form uneven portions at equal intervals in the circumferential direction of the raw tube M, the rolls 11, 1
6 and the opening angle α with respect to the base tube M (FIG. 6
a) was set to 120 degrees.

In the first-stage molding, the necessity of the deformed pipe P and the width w of the convex portion are set to 19 mm and uniform in the circumferential direction. From the deflection of the roll shaft and the gap between the bearing and the roll shaft, the value of a is 0.25 m.
m was determined in advance. From the value of a, the width W2 between the ridges at the roll division position was set to 18.75 mm, and the width W1 between the other ridges was set to 19 mm. In the second-stage molding, in order to set the required convex portion width w of the deformed pipe P to 16.6 mm, since a was 0.3 mm, the width W2 between the raised portions at the roll dividing position was 16.3 mm. The width W1 between the other raised portions was 16.6 mm.

The forming rolls 11 to 11 of the preforming stand 10
14 was set to 1.5 mm, and the reduction amounts of the forming rolls 21 to 24 of the finish forming stand 20 were set to 2 mm.
The tube M sent at a speed of m / min was made uneven. The rotation of the forming rolls 11 to 14 and 21 to 24 was a driven rotation due to sliding friction with the base tube M. As a result of molding under these conditions,
A modified tube P having an outer diameter of 50.4 mm and a convex portion height of 6 mm can be formed, and a convex portion width w of 16.6 mm has a very small variation in the circumferential direction as shown in FIG. was gotten. Further, the radius of curvature R of the outer surface of the convex portion was also excellent in uniformity as shown in FIG.

[0023]

Second Embodiment Forming Rolls 11 to 1 at Spiral Angle θ = 5 °
4, 21 to 24 are attached to the roll chock 43 (FIG. 10), and the preforming stand 10 and the finish forming stand 2
Example 1 except that the base tube M was formed while rotating 0.
A modified tube P was manufactured under the same conditions as described above. Obtained deformed pipe P
Has a spiral angle of 5 degrees, an outer diameter of 50.4 mm, and a convex portion width w.
Is a deformed tube P for 16.6 mm as shown in FIG.
The variation was very small in the circumferential direction. Further, the radius of curvature R of the outer surface of the convex portion was also excellent in uniformity as shown in FIG.

[0024]

COMPARATIVE EXAMPLE Assuming that a = 0 mm, the first-stage forming roll 11
To 14 are all 19 mm, the width between the raised portions of the second-stage forming rolls 21 to 24 is a = 0 mm, and all 1
A modified pipe P was manufactured under the same conditions as in Example 1 except that the diameter was 6.6 mm. In this case, since the width W2 between the protruding portions at the roll division position became larger than the set value, the width w of the convex portion of the deformed pipe P varied greatly with respect to 16.6 mm. Also,
The variation in the radius of curvature R of the outer surface of the convex portion was also increased, and the uniformity of the cross-sectional shape in the circumferential direction was greatly broken.

[0025]

As described above, in the present invention, the roll dividing position is set at the boundary between the roll bottom of the forming roll and the roll bulge of the adjacent forming roll, and the calculation is performed in consideration of the rigidity of the forming stand. The target deformed tube is formed with a forming roll having an optimum width between raised portions obtained from the formula. In addition, since the molding stands are arranged in multiple stages, the amount of reduction in each stage can be reduced, so that the gap between the rolls can be narrowed. According to this method, the deformation direction of the raw tube is regulated by the concave portion formed by the preforming, so that the cross-sectional shape does not largely collapse. Also, it is not necessary to determine the optimum dimensions of the forming rolls by experiments with several types of forming rolls. Therefore, a deformed pipe in which a plurality of uneven portions having high symmetry are provided in the circumferential direction can be manufactured at low cost and high efficiency.

[Brief description of the drawings]

FIG. 1 shows a conventional forming roll combination (a) used for manufacturing eight sets of irregularly shaped pipes with irregularities and a defective cross-sectional shape (b) which is likely to occur when forming a deformed pipe in-line by a conventional method. )

FIG. 2 shows a conventional arrangement of forming rolls divided into 180 degrees (a) or 90 degrees (b).

FIG. 3 is an explanatory diagram showing that a deformed pipe P is manufactured with a conventional roll arrangement, and that a shape collapse occurs.

FIG. 4 is an explanatory view showing a state before (a) and during (b) forming of a forming roll.

FIG. 5 is a schematic side view of a manufacturing apparatus according to the present invention.

FIG. 6 is a schematic view of the forming rolls of the preforming stand (a) and the finish forming stand (b) viewed from the tube axis direction of the raw tube.

FIG. 7 is a schematic diagram of a roll support mechanism that enables the forming roll to move forward and backward with respect to the center of the raw tube.

FIG. 8 is an explanatory view showing that a deformed pipe having a good cross-sectional shape is manufactured.

FIG. 9 is a cross-sectional view of an elemental tube in which plate ends overlap.

FIG. 10 is a roll supporting mechanism used for manufacturing a deformed pipe having an uneven portion spirally formed in the pipe axis direction.

FIG. 11 shows a distribution of a deformed pipe P having a convex width w in a circumferential direction.

FIG. 12 shows the distribution in the circumferential direction of a deformed pipe P having an outer radius of curvature R.

[Explanation of symbols]

10: Preforming stand 20: Finish forming stand 11-14, 21-24: Forming roll of preforming stand and finishing stand 11p-14p, 21p-24p: Ridge attached to forming roll of preforming stand and finishing stand 11b To 14b, 21b to 24b: Bottom of forming roll of preforming stand and finishing stand M: Raw tube P: Deformed tube p: Convex b: Concave θ: Spiral angle D: Roll gap G: Gap between forming rolls
t: apex of convex part of deformed pipe α: division angle of forming roll e: end of plate at unwelded part of raw pipe w: required width of convex part of deformed pipe W1: width between raised parts other than roll division position W2: roll The width between the protruding portions at the dividing position r: Set amount of reduction r _T : The amount of reduction actually applied to the raw tube a: Coefficient determined by the rigidity of the forming stand, etc. 1: Forming roll 2: Lower part of forming roll 3
0, 40: roll support mechanism 31, 45: roll shaft 32, 43: roll chock 33: screw down screw 41: roll accommodation space
44: Color

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Tsutomu Higashi 1 Tsurumachi, Amagasaki City, Hyogo Prefecture Inside Nisshin Steel Co., Ltd.Technical Research Laboratory (72) Inventor Hiroshi Asada 1 Tsurumachi Amagasaki City, Hyogo Prefecture Nissin Steel Co., Ltd. F-term in the Technical Research Laboratory (reference) 4E028 EA02 EA03 4E063 AA04 BB05 EA06 EA11 MA01

Claims (4)

[Claims] 1. When manufacturing a deformed tube having a plurality of sets of concave portions and convex portions in a circumferential direction from a cylindrical raw tube, a total number corresponding to the number of the concave portions is arranged in a circumferential direction of the raw tube. A plurality of preforming rolls having a raised portion and a roll bottom portion between the raised portions, and a roll dividing position is set at a boundary between a roll bottom of a certain preformed roll and a raised portion of an adjacent preformed roll. The width between the raised portions at the roll division position is set to the value of the following formula (1), and the plurality of preforming rolls are preformed on a preforming stand in which the plurality of preforming rolls are arranged in the circumferential direction of the raw tube. After the concave portion corresponding to the concave portion is attached to the base tube, a plurality of rolls having the same protruding portion position and the width between the protruding portions at the roll dividing position set by the following formula (1) are arranged at the same roll dividing position. Target on finishing stand with finishing forming rolls A method for producing a deformed pipe, which comprises finishing forming a raw pipe into a shape. W2 = wa (1) Here, w is the required width of the convex portion of the deformed pipe, W2 is the width between the raised portions of the forming rolls at the roll dividing position, and a is the width between the rolls that expands during forming. This is a preset value. 2. The deformed pipe according to claim 1, wherein the pipe is formed by a preforming roll and a finishing roll in which the roll axis is inclined at a predetermined spiral angle with respect to a plane perpendicular to the pipe axis of the raw pipe. Production method. 3. A plurality of preforming rolls having the same total number of protrusions as the recesses to be formed in the raw tube formed on the roll peripheral surface and having a bottom between the protrusions as a roll. A roll dividing position is set at a boundary between the bottom and the adjacent preformed raised portion, and the width between raised portions at the roll dividing position is a value of the following formula (1). A preforming stand arranged in the circumferential direction of the pipe and a plurality of rolls arranged at the same roll division position having the same ridge position and the width between the ridges at the roll division position set by the following equation (1). An apparatus for manufacturing a deformed pipe, comprising: a finish forming stand having a finish forming roll. W2 = wa (1) Here, w is the required width of the convex portion of the deformed pipe, W2 is the width between the raised portions of the forming rolls at the roll dividing position, and a is the gap between the rolls that expands during forming. This is a preset value. 4. The apparatus for manufacturing a deformed pipe according to claim 3, wherein the roll axes of the preforming roll and the finish forming roll are inclined at a predetermined spiral angle with respect to a plane perpendicular to the pipe axis of the raw pipe.