US3916663A

US3916663A - Apparatus for forming spiral steel pipe

Info

Publication number: US3916663A
Application number: US435964A
Authority: US
Inventors: Kazuma Takeshita; Kenji Sato; Yasumi Shimazaki
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1973-01-24
Filing date: 1974-01-23
Publication date: 1975-11-04
Anticipated expiration: 1992-11-04
Also published as: CA991026A; BR7400492D0; JPS535088Y2; JPS49114238U; DE2402579A1

Abstract

An apparatus for forming spiral steel pipe by spirally curling a strip of metal with a row of interior forming rolls set on an interior forming stand and rows of exterior forming rolls respectively set on exterior forming stands. A mount is provided which extends in the direction of axis of the interior forming stand in such a manner as to cover the interior forming stand wholly except the part thereof equipped with the interior forming rolls; and a plurality of rows of interior supporting rolls are disposed on the outer surface of the mount nearly in parallel with the edges of the spiralled strip.

Description

Unite Sites atet 1191 1 1 3,916,663

Takeshita et al. Nov. 4, 1975 APPARATUS FOR FORIVHNG SPIRAL 3,650,015 3/1972 Davis 29/4777 STEEL PIPE 3,776,010 12/1973 Krakow 72/12 [75] Inventors: Kazuma Takeshita, Kitakyushu;

Kenji Sam, H Ya j Primary Exammer-C. W. Lanham Shimazaki, Kit k h ll of Japan Assistant ExaminerRobert M. Rogers Attorney, Agent, or Firm-Wenderoth, Lind & Ponack [73] Asslgnee: Nippon Steel Corporation, Tokyo,

Japan 22] Filed: Jan. 23, 1974 ABSTRACT [21] Appl, N 435,964 An apparatus for forming spiral steel pipe by spirally curling a strip of metal with a row of interior forming rolls set on an interior forming stand and rows of exte- [30] Foreign Application Priority a rior forming rolls respectively set on exterior forming Jan. 24, 1973 Japan 48-11067 stands. A mount is provided which extends in the direction of axis of the interior forming stand in such a manner as to cover the interior forming stand Wholly [51] Int. Cl. BZIF 3/02 except the part thereof equipped with the interior Field of Search 72/49, forming rolls; and a plurality of rows of interior sup- 200 559 porting rolls are disposed on the outer surface of the mount nearly in parallel with the edges of the spiralled [56] References Cited strip.

UNITED STATES PATENTS 3,146,331 8/1964 Schubert 72/135 6 clamslo Drawmg F'gures U.S. Patent Nov. 4, 1975 6 Sheet 10f2 3,916,663

FIG. /0 FIG. lb PRIOR ART" PRIOR ART T R A m m 3 PRIOR ART PRIOR ART US. Patent Nov. 4, 1975 Sheet 2 of2 3,916,663

APPARATUS FOR FORMING SPIRAL STEEL PIPE BACKGROUND OF THE INVENTION The present invention relates to apparatus for forming helical pipe by curling a strip of metal into a convolution.

Generally in the case of manufacturing spiral steel pipe, a strip of steel is curled spirally into a cylindrical pipe by using a forming apparatus, and the opposite edges of the helical convolutions of the strip are welded.

One type of known apparatus for the manufacture of spiral steel pipe is shown in FIGS. 1a and 1b in which a row of interior forming rolls (3) set on an interior forming stand (4) and two rows of exterior forming rolls (5), (5) set on respective exterior forming stands (6), constitute an arrangement of rolls in the form of a triangle, in which the roll (3) is the apex and the rolls (5), are the base, sectionally sectionaly shown in of FIG. 1a, thereby curling strip fed continuously, into a convolution, thus; forming pipe (2). However, in the formation of such pipe only with the abovementioned interior and exterior forming rolls, it is difficult to maintain a constant outer diameter of the pipe. This difficulty causes the edges of the strip to fail to come together at the welding point (W), making welding operations inefficient and the quality of the weld poor.

In order to solve the abovementioned problem in the formation of pipe, the device as illustrated in FIGS. 2a and 2b has been used. According to FIG. 2, the interior forming stand (4) has, at its head, a plurality of interior supporting rolls (7) disposed radially at the prescribed size of the inner diameter of the pipe, so that the inner diameter may be maintained as prescribed. The addition of such rolls may be effective in the manufacture of spiral steel pipe of better commercial value than that manufactured by the abovementioned triangular arrangement of rolls.

However, in the case of using the forming apparatus of FIG. 2, the spiralled strip (2) is supported from the inside only on one part of the same, the rest being drawn toward the axis of the pipe over the interior supporting rolls (7), causing divergence of the edges of the strip at the welding point (W), making it very difficult to manufacture pipe of high commercial value.

Another drawback of the forming apparatus using interior supporting rolls for supporting the spiralled strip only on one part, is that trouble takes place at the start of welding operation.

In the normal type of welding of plate, it is the practice at the restart of welding after an interruption for preventing possible inefficient penetration that the tobe-welded part of the piece of plate for the next welding is laid on the welded part of the preceding piece. This practice should apply to welding for forming helical pipe. However, the normal type of the apparatus for forming helical pipe has no driving source for interior and exterior forming rolls (3) and (5); strip (1) is fed by means of a pinch roll (8); therefore, at the reopening of welding, the pinch roll (8) is rotated reversely so that the strip (8) is drawn back somewhat in the direction of arrow, to cause the to-be-welded following piece of strip laid over existing pipe thereon. As a result, the formed pipe (2) is squeezed only on the right side in FIG. 4, therefore, welding restarts with abnormal forming conditions. As such welding proceeds, the

formed pipe takes on a deformation, making it impossible to even resume normal forming conditions.

SUMMARY OF THE INVENTION The present invention seeks to solve these problems, including the abovementioned, inherent in the conventional type of the apparatus for forming spiral steel pipe; and its special characteristic lies in that as an improvement of the apparatus for forming pipe by spirally curling a strip of steel with interior forming rolls and exterior forming rolls, the three rows of which form a triangle when viewed in section, a mount is provided which extends in the direction of the axis of the interior forming stand in such a manner as to cover the interior forming stand completely except the part thereof equipped with interior forming rolls; and a plurality of rows of interior supporting rolls are disposed on the outer surface of the mount nearly in parallel with the edges of the spiralled strip.

An object of the present invention is to provide an apparatus for forming spiral steel pipe having a good quality of the spiral seam between the edges of the spiralled strip, as a result of infallibly accurate covergence edges of the spiralled strip.

Another object of the present invention is to provide an apparatus for forming spiral steel pipe with the ability to restart the welding operation after an interruption, while maintaining the constancy of forming conditions.

A further object of the present invention is to provide an apparatus for forming spiral steel pipe with the ability to produce steel pipe of good quality.

These and other objects of the present invention will be made clearer by the following description of the present invention in the light of attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1a and lb are front and side explanatory views showing the principle of a prior art apparatus for forming spiral steel pipe;

H FIGS. 2a and 2b are front and side explanatory views of another conventional type of apparatus for forming spiral steel pipe;

FIG. 3 is a side view of the forming apparatus of FIGS. 2a and 2b showing a problem which occurs therewith;

FIG. 4 is an explanatory plan view of the forming apparatus of FIGS. 2a and 2b, showing forming conditions at the restart of welding after an interruption;

FIGS. 5a and 5b are front and side explanatory views of an embodiment of the apparatus of the present invention for forming spiral steel pipe;

FIG. 6 is a longitudinal sectional view of an embodiment of a mechanism for controlling the positions of interior supporting rolls for use in the forming apparatus of the present invention; and

FIG. 7 is a longitudinal sectional view of another embodiment of the mechanism as shown in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIGS. 5a and 5b, a long metal strip 11 is fed continuously into the forming apparatus by means of a pinch roll (not shown) to form a; (12) indicates cylindrical pipe 12 having a welded seam (s) between the edge portions of the spirally curled strip. A plurality of interior forming rolls (13) is disposed in a row on an interior forming stand (14). Two rows of exterior forming rolls (15) are provided, one on each of two exterior forming stands 16. Each set of an interior forming roll (13) and two adjacent exterior forming rolls (15) on the respective stands (16) are at the corners of said interior forming roll (13) being at the apex thereof. These rolls are used to curl strip 11 which is supplied at a prescribed oblique angle, into a spirally formed pipe.

According to the present invention, there is provided mount (17) which covers the interior forming stand (14) wholly except for the part equipped with the row ofinterior forming rolls (13). The mount (17) has a polygonal cross-section, and extends along the long axis of the interior forming stand (14) for a part of the length thereof. On the mount (17) there are provided a great number of interior supporting rolls (18) in a plurality of plural rows (P P P each running nearly parallel with the seam(s) between the edge portions of the spiralled strip (12). Therefore, the disposition of interior supporting rolls (18) is also spiral, and each roll has a shaft extending nearly perpendicular to the seam(s) between the edge portions of the spiralled strip.

There is no particular distance (h) between adjacent rows of said interior supporting rolls (18), but it is desirable that such rolls should be so arranged as to support the strip 11 at more than two positions within the width (H) of the spiralled strip along the axis of the formed pipe and also as near as possible to both edge portions of the spiralled strip. As for the number (Pn) of rows of said interior supporting rolls, it is preferred that there be three to five rows inordinary cases, but the invention is not limited thereto.

According to the present invention, the radial position of said interior supporting rolls (18) is made adjustable by providing adjusting units (19) between said interior supporting rolls (18) and the mount (17), so as to adjust the diameter of the spirally formed pipe (12). As shown in FIG. 5, a plurality of said adjusting units (19) are provided on the polygonal mount (17), one on each face of said mount, parallel to the axis of the formed pipe (12); and on each adjusting unit there are provided for free rotation interior supporting rolls (18) in a number corresponding to the plurality of rows of such rolls. As shown, a number of interior supporting rolls (18) are mounted on each adjusting unit (19). This is only for convenience. According to the present invention, there is no limitation on the number of such rolls on one such member, so that it is possible to set one such roll on one adjusting unit, making each roll controllable independently from the others.

For details of the adjusting unit (19.), reference is made to FIGS. 6 and 7, both showing embodiments of such a member according to the present invention.

The adjusting unit of FIG. 6 consists of a pair of blocks, that is, a radially outer block (20) and a radially inner sliding block (21); and the contact-sliding surface (22) of the respective blocks is in the form of wedges corresponding to each other. On the outer block (20) are mounted inner supporting rolls (18), each being on a mounting block (23). At one end of the inner sliding block (21) is a freely rotatable threaded rod (24) connected to block (21) by an appropriate type of joint, and threadedly engaged with nut (25) fixed on the mount (17), so that the turning of the threaded rod 24 causes the rod to move horizontally through the nut (25), thereby pushing forward or drawing back the inner block (21).

As the inner block (21) moves forward or backward, the outer block moves radially outwardly or inwardly, thereby changing the radial position of the interior supporting roll (18). The outer block (21) is mounted on the mount (17) only for radial movement.

FIG. 7 shows another embodiment of the adjusting unit according to the present invention.

The bottom of the mounting block (26) for each interior supporting roll (18) is in the form of a wedge, and contacts the wedge on the inner block (27) directly. Therefore, the outer block (28) functions merely as a guide for the mounting block (26), supporting this block for radial movement. Therefore, as in the embodiment of FIG. 6, the radial positions of the interior supporting rolls 18) are changed by the turning of the threaded rod (24).

Needless to say, any other appropriate means than that described above may be used, according to the present invention, for making the abovementioned adjusting unit function and for horizontal movement of the lower block.

Also according to the present invention, interior supporting rolls are disposed spirally in plural rows, thereby making the positions for supporting the periphery of the spirally formed pipe by interior supporting rolls relatively constant as viewed sectionally of the pipe; also as such supporting is near the seams between the edge portions of the spiralled strip and at constant distances along the axis of the pipe, forming operations can be made stable and accurate, completely preventing offset of the welded part which may occur due to imbalance of the supporting positions. Within a certain range, the height of the interior supporting rolls can be changed by using the adjusting unit, making it possible to adjust the diameter of the formed pipe.

What is claimed is:

1. In an apparatus for forming spiral steel pipe by spirally curling metal strip, the apparatus having a row of interior forming rolls mounted on an interior forming stand and a plurality of rows of exterior forming rolls mounted individually on two exterior forming stands, the improvement comprising a mount extending in the direction of the axis of the interior forming stand and covering the peripherial parts of said interior forming stand other than the part directly supporting the'row of the interior forming rolls; a plurality of interior supporting rolls on said mount for contracting the inner surface of the pipe being formed where the edges of the strip have not been welded together, said interior supporting rolls being along a plurality of spiral lines in the peripheral direction of the pipe aligned nearly parallel with the strip edges to be joined for forming the pipe being formed.

2. The improvement as claimed in claim 1 in which said interior supporting rolls are in rows in the axial direction of the interior forming stand with the rows spaced around the periphery of said mount and the interior supporting rolls in each row being in a space corresponding to the width of the metal strip.

3. The improvement as claimed in claim 2, wherein said interior supporting rolls in the rows are at positions as near as possible to the edges of the spiralled strip.

4. The improvement as claimed in claim 1, further comprising adjusting means for said interior supporting rolls mounted on said mount.

5. The improvement as claimed in claim 4, wherein each said adjusting means comprises a pair of blocks, one laid over the other, the contacting surfaces of said blocks being in the form of wedges corresponding to each other, the radially outer block having at least one interior supporting roll mounted thereon and the radially inner block having means thereon for moving said inner block relative to said interior forming stand and mount to move said outer block radially.

6. The improvement as claimed in claim 4, wherein each interior supporting roll has a mounting block on which it is mounted, and each said adjusting means

Claims

1. In an apparatus for forming spiral steel pipe by spirally curling metal strip, the apparatus having a row of interior forming rolls mounted on an interior forming stand and a plurality of rows of exterior forming rolls mounted individually on two exterior forming stands, the improvement comprising a mount extending in the direction of the axis of the interior forming stand and covering the peripherial parts of said interior forming stand other than the part directly supporting the row of the interior forming rolls; a plurality of interior supporting rolls on said mount for contracting the inner surface of the pipe being formed where the edges of the strip have not been welded together, said interior supporting rolls being along a plurality of spiral lines in the peripheral direction of the pipe aligned nearly parallel with the strip edges to be joined for forming the pipe being formed.

6. The improvement as claimed in claim 4, wherein each interior supporting roll has a mounting block on which it is mounted, and each said adjusting means composes a pair of blocks, one laid over the other, the radially outer block having at least one aperture therein in which the mounting block of an interior supporting roll is radially guided, and the radially inner block having a surface in the form of a wedge contacting the inner end surface of the mounting block of the interior supporting roll and further having means thereon for moving said inner block relative to said interior forming stand and said mount to move said mounting block radially.