KR101752290B1 - Improved method and apparatus for making pipe - Google Patents

Abstract

A pipe making method and a molding machine are disclosed, wherein a pipe making method of the present invention comprises the steps of: (a) preparing a molding machine in which a longitudinal section forms a closed loop; (b) curving the edge portion of the one end while moving the plate material such that an edge portion of one end in the transverse direction of the plate material passes through the closed loop; (c) moving the plate through the closed loop until the molding machine reaches an edge of the other transversely opposite end of the plate; (d) curving the edge of the other end while moving the plate so that the edge of the other end passes through the closed loop; And (e) shaping the plate into which the edge portions at both ends are bent, into a pipe shape.

Description

TECHNICAL FIELD [0001] The present invention relates to an improved pipe making method,

The present invention relates to an improved pipe making method and a molding machine.

The transportation method using the line pipe is most efficient for the transportation of long distance gas or gas with the increase of the global energy demand. Such a line pipe can maximize its efficiency by increasing the transport pressure of the fluid in the pipe, that is, raw oil or gas. In order to increase the fluid transportation pressure, it is necessary to increase the strength of the pipe base material.

Currently, steels for line pipe, which are usually X70 grade or lower, are mainly used as pipe base materials. It is possible to reduce the construction cost of the line pipe by reducing the weight of the steel material through reduction of the diameter and thickness of the line pipe as well as to improve the transportation efficiency with the increase of the transportation pressure, (Pipe-to-pipe welding), which occupies a large part of the entire length of the pipe, can be reduced, thereby greatly reducing the construction cost.

A UOE pipe making method is known as a pipe making method for manufacturing such a pipe, and a brief description thereof is as follows.

First, C-crimping is performed to bend both ends of a plate using a C-molding machine, and then U-press is performed to transform the plate into a letter U shape using a U- . The U-shaped plate material that has undergone U molding is pressed between the upper molding machine and the lower molding machine of the O molding machine having a semicircular face, and the O-molding is performed in which the molding is deformed into an alphabet O shape. The O-shaped steel pipe is subjected to a tack welding process for fixing the pipe caused by a spring back phenomenon for pipe welding, and is then subjected to a submerged arc welding process, And pipe manufacturing is completed by expanding for the purpose of improving roundness and reducing residual stress during molding.

Such a UOE pipe making method is advantageous in that a pipe having a length of 12 m or more can be mass-produced by a short-time molding, and the quality of the pipe is improved because it includes an expanding process.

However, as disclosed in Korean Patent Publication No. 1382788 (entitled "Crafting method and C molding machine"), the C molding machine used in the conventional UOE casting machine is required to have a molding machine for each steel pipe diameter, There has been a problem that another molding machine suitable for the production of pipes having a standard size has to be additionally manufactured.

The present invention has been made to solve the above problems of the prior art and it is an object of the present invention to provide an apparatus and a method for securing an expandability capable of manufacturing pipes of various sizes using one molding machine, And an object of the present invention is to provide an improved pipe making method and a molding machine capable of reducing the size of the pipe.

According to a first aspect of the present invention, there is provided a pipe trenching method comprising the steps of: (a) preparing a molding machine in which a longitudinal section forms a closed loop; (b) curving the edge portion of the one end while moving the plate material such that an edge portion of one end in the transverse direction of the plate material passes through the closed loop; (c) moving the plate through the closed loop until the molding machine reaches an edge of the other transversely opposite end of the plate; (d) curving the edge of the other end while moving the plate so that the edge of the other end passes through the closed loop; And (e) a step of shaping the plate material curved at both ends of the plate into a pipe shape, wherein the molding machine is provided on the upper and lower surfaces of the inside of the closed loop, Wherein in the step (b) and the step (d), the molding machine further comprises a curved pressing part for pressing one or more curved pressing parts in correspondence with the movement of the plate material so that the curved pressing part can bend each of the edge parts at both ends And can be rotationally driven and linearly driven.

According to a second aspect of the present invention, there is provided a molding machine for bending an edge portion at both lateral ends of a plate material, the molding machine comprising: a body forming a closed loop through which one end in the transverse direction of the plate can pass; ; A curved pressing portion provided on an upper surface and a lower surface of the inside of the closed loop for pressing at least one of upper and lower surfaces of the edge portions at both ends; And a driving unit for rotationally driving and linearly driving the body corresponding to the movement of the plate material so that the curvature-pressing unit may bend each of the edge portions at both ends.

According to the above-mentioned problem solving means of the present invention, it is possible to secure the expandability that enables the production of pipes of various sizes by using one molding machine, and to reduce the area in which the molding machine is installed compared with the conventional molding machine An improved pipe forming method and a molding machine can be provided.

In addition, it is possible to manufacture a steel pipe with excellent performance quickly and stably by simply integrating heating and curving processes at both edge portions using a single molding machine.

1 is a graph showing the relationship between strength and formability.
2 is a sectional view of a steel pipe showing a picking angle.
FIG. 3 is a conceptual diagram showing a molding machine and a sheet material according to one embodiment of the present invention in a three-dimensional view.
FIGS. 4 and 5 are views for explaining the operation sequence of the molding machine according to one embodiment of the present invention.
6 is a partial perspective view showing a state in which a reinforcing portion is added to a molding machine according to an embodiment of the present invention;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is " on " another member, it includes not only when the member is in contact with the other member, but also when there is another member between the two members.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

Hereinafter, a pipe making method according to one embodiment of the present invention will be described.

The material of the steel pipe to be processed in one embodiment of the present invention may be the material disclosed in Patent Application No. 2006-107917, but is not limited thereto. The welding material used in one embodiment of the present invention may be a welding material of Patent Application No. 2007-81137, but the present invention is not limited thereto.

In addition, the present invention is an improvement of the C molding machine, and the U-molding machine, the O-molding machine, the welding method, the expanding method and the like are the same or similar to the conventional UOE method in addition to the C molding machine, and a detailed description thereof will be omitted.

Hereinafter, a method of manufacturing a UOE steel pipe using an improved C molding machine will be described as an embodiment, but the present invention is not limited thereto. For example, the present invention can be applied to other steel pipe manufacturing methods, such as JCOE steel pipe manufacturing methods, which are formed by using an improved C molding machine.

Fig. 1 shows the relationship of the formability to the strength in the steel sheet. As shown in Fig. 1, since the strength and formability of the steel sheet have an inverse relationship, the higher the strength, the worse the formability becomes, and the more the formability becomes, the lower the strength.

In particular, referring to Fig. 2 showing a section of a steel pipe showing a picking angle, the welded portion of the steel pipe has a low strength due to the influence of the heat affected portion. In the case where the picking angle? This causes breakage of the welded portion of the steel pipe in the post-process expansion process, which makes the pipe impossible.

Such a picking angle? Is determined by C molding performed at the beginning of the pipe making process. However, the higher the strength of the plate material, the worse the formability is, and even if the C molding is performed, the picking angle?

However, the C forming that affects the picking angle? Is to form only the edge portion of the plate material, and the edge portion of the plate material is a portion that is heated by welding later, so that the heat treatment process until welding does not affect the performance of the steel pipe. The present method is based on this point and attempts to secure the moldability of the C molding through local heating of the edge of the plate rather than the overall heating of the plate.

FIG. 3 is a conceptual view showing a molding machine and a plate material in a three-dimensional view according to an embodiment of the present invention, and FIGS. 4 and 5 are views for explaining an operation sequence of the molding machine according to an embodiment of the present invention

3 to 5, the inventor of the present invention has found that a curved pressing portion 51 for heating and curving an edge portion E of a plate material P is disposed on the inner upper surface of the closed loop 50a of the molding machine 50, So that the process of heating the edge portion E of the plate material P and the process integration method in which the C molding process can be continuously performed without being separated by a separate process that is discontinuous have been developed.

The inventor of the present application has found that the molding machine 50 can form the closed loop 50a through which the plate material P can pass so that the both end edge portions E of the plate material P are completely C can be formed, and the expandability capable of producing pipes of various sizes can be secured. In the state where one molding machine 50 is provided, the plate material P passes through the closed loop 50a of the molding machine 50, Since the C molding corresponding to the steel pipe standard can be performed, the area (space) in which the molding machine 50 is installed can be greatly reduced as compared with the conventional case where the molding machine is arranged for each steel pipe standard.

4, the present sewing method includes a step S1 of preparing a molding machine 50 having a longitudinal section forming a closed loop 50a, a step S1 of forming a closed loop 50a, and a step E of a lateral direction (width direction) (S2) curving the edge portion (E) of one end of the plate material (P) while moving the plate material (P) so that the plate material (P) passes through the closed loop (50a). Considering that the length of the plate material P in the longitudinal direction (1 o'clock-7 o'clock direction in FIG. 3, lengthwise direction) is about 13 m when transporting pipes (steel pipes) The longitudinal (longitudinal) width can be set so as to surround the plate material P having such a longitudinal length of up to 13 m.

4 and 5, the present sewing method is repeated until the molding machine 50 reaches the edge E at the other end in the transverse direction (width direction) of the plate material P And moving the plate material P through the closed loop (S3). 5, in the present sewing method, a step of bending an edge portion of the other end of the plate material P while moving the plate material P such that the edge portion E at the other end of the plate material P passes through the closed loop 50a (S4).

The present manufacturing method may include a step (S5) of shaping the plate member in which the edge portions E at both ends of the plate member P are curved, into a pipe shape.

The molding machine 50 is provided on the upper and lower surfaces inside the closed loop 50a and includes a curved pressing portion 51 for pressing at least one of the upper surface and the lower surface of each of the edge portions E at both lateral ends of the plate material P ). 4 and 5, when the edge portion E of the plate P is moved while passing through the closed loop 50a of the molding machine 50, at least a part of the curved pressing portion 51 Can be in line contact with at least one or more of the upper surface and the lower surface of the edge portion (E). By performing the pressing in this line contact state, the frictional action of the molding machine 50 with respect to the edge portion E is minimized, so that a more natural curved forming (C molding) can be achieved. Further, the curved pressing portion 51 may be provided in the form of a roller capable of rotating in a predetermined manner in order to perform pressing while minimizing friction. However, the curvature pressing portion 51 is not limited to a roller form, and may be provided in a fixed curved surface shape that is not rotated if necessary.

The molding machine 50 causes the curved pressing portion 51 to press each of the edge portions E at both ends of the plate material P in the step S2 (the step of curving the plate material at one end edge portion) and the step S4 (the step of curving the edge material at the other end portion of the plate material) And is rotationally driven and linearly driven corresponding to the movement of the plate material P so as to be able to bend.

In step S2, the molding machine 50 continuously presses the portion of the edge portion E of the plate material P pressed by the curved pressing portion 51 by a predetermined angle, and presses the closed loop 50a It may be set to a rotation state and a position state different from those of the molding machine 50 in the step S1.

In this regard, referring to FIG. 4, the first dx of the edge portion E of the sheet material P is bent by the angle a, passes through the closed loop 50a, is bent by the angle a by the second dx, 50a, the first dx portion is bent twice by the angle 2a with respect to the plate material P by accumulating two bends. As described above, the molding machine 50 can be rotationally driven and linearly driven so that pressurization for continuous bending can be performed in step S2. 4, in step S2, the molding machine 50 is rotated in the clockwise direction so as to be pressed so as to form an edge portion E bent upward with respect to the plate material P moved in the 9 o'clock direction And a positional state shifted upward by a predetermined displacement in the 12 o'clock direction. At this time, the rotation state and the position state can be set to be finely changed with time so that the edge portion E can be bent in a desired shape.

4, the desired curved shape of the edge E at one end of the plate P in the step S2 indicates that the molding machine 50 is positioned in the inner direction of the edge E (The direction of 12 o'clock in FIG. 5) and passes through the closed loop 50a as the edge portion E enters in the direction of the arrow.

Next, in the step S4, the molding machine 50 is configured such that the curved path in which the curved pressing portion 51 can bend the edge portion E at the other end of the plate material P is formed in combination with the movement of the plate material P , And can be continuously driven and linearly driven.

Referring to FIG. 5, the curved path may be defined as a relative path in which the molding machine 50 is rotationally driven and linearly driven with respect to the movement of the plate P. If it is assumed that the plate material P is not moved to the left side (reference to FIG. 5), the molding machine 50 is moved to the right (reference to FIG. 5) Lt; / RTI > However, since the plate material P is moving to the left in this embodiment, the molding machine 50 forms a curved path relative to the plate material P when the plate material P is rotationally driven and linearly driven in accordance with the plate material P being moved, The edge E of the other end can be bent.

As described above, the step S2 is a step of bending the edge portion while the molding machine 50 enters the edge portion E of one end of the plate material P, while the step S4 is a step of bending the molding machine 50 to the other end The driving of the molding machine 50 in both steps S2 and S4 can not help but be set differently.

That is, in the step S2, the molding machine 50 may be driven in the same or similar manner as shown in FIG. 4 such that the bending is continuously accumulated and curved with respect to the moving edge passing through the closed loop 50a. On the other hand, unlike the step S2, in the S4 step, since the molding machine 50 has to curl outward from the edge portion, the molding machine 50 relatively moves the curved path that curves the edge portion E with respect to the plate material P, And the edge portion must be curved in the desired shape.

Referring to FIG. 5, the relative curved path formed by combining the movement of the plate P and the rotation and linear driving of the molding machine in step S4 indicates that the molding machine 50 is located outside the edge E (At the reference 3 o'clock direction in Fig. 5) and upward (12 o'clock in Fig. 5 direction) as the distance increases.

In order to drive and control the molding machine 50, the molding machine 50 performing the present manufacturing method may include a structure of a driving unit (not shown) for moving the molding machine 50. In addition, the molding machine 50 for performing the present manufacturing method may include a controller for controlling the driving unit, a heating unit, and the like, which will be described later. Various known devices widely known to those skilled in the art may be applied to each of the driving part and the control part.

In other words, the molding machine 50 performing the present tube making method may include a heating unit (not shown) heating the inside of the closed loop 50a.

The heating unit heats each of the edge portions E at both ends of the plate material P in accordance with the movement of the plate material P in the steps S2 and S4 and the curved pressing portion 51 is heated by the heating unit The edge portion can be pressed and bent.

In step S2 or step S4, the heating of the heating part is preferably performed at a temperature at which no phase change occurs, that is, at a temperature equal to or lower than the A1 temperature, since it does not affect the structure. Here, the temperature A1 is preferably controlled to be in the range of 600 to 700 占 폚. If the heating temperature is lower than 600 ° C, the improvement in the formability due to heating is insufficient. If the heating temperature is higher than 700 ° C, there is a risk of phase change exceeding the A1 temperature.

In addition, in the present invention, it is sufficient to secure only the formability of the edge portion of the plate material. Since the portion other than the edge portion is not a portion heated by welding, induction heating capable of locally heating only the edge portion of the plate is preferable, because the performance of the steel pipe may be deteriorated when heated.

That is, the heating unit may be configured to perform low-frequency induction heating so that the edge portion E is uniformly heated in the thickness direction. Particularly, since uniform heating is required in the thickness direction of the edge portion, low-frequency induction heating having a frequency range of 5 kHz or less is preferable. When the frequency range exceeds 5 kHz, only the surface temperature rises and the moldability may not be increased.

Since the curved pressing portion 51 and the heating portion are provided together in the molding machine 50 itself, the curving process can be performed successively after the edge portion E is heated, so that higher moldability can be secured And stable C molding can be performed, and since the process is simplified, the molding can proceed more quickly and efficiently. Further, in the step S2 or S4, the step of heating the edge portion E and the step of bending the edge portion E may be performed in an overlapping manner for at least part of the time, In the direction in which the curvature can be efficiently performed.

6 is a partial perspective view showing a state in which a reinforcing portion is added to a molding machine according to an embodiment of the present invention;

Referring to FIG. 6, the molding machine 50 performing the present manufacturing method includes a reinforcing portion 53 (longitudinal direction) provided on the outer side surface and the outer side surface in the longitudinal direction so as to prevent deformation when the curved pressing portion 51 is pressed, ).

The reinforcing portion 53 may be a member for reinforcing the rigidity of the upper and lower members of the molding machine 50 and may include a web element provided at the lower portion of the upper portion of the molding machine upper member and the lower portion of the lower member, , Whereby the bending deformation and the like of the molding machine (50) can be prevented. Illustratively, the abdominal member of the reinforcing portion 53 may be provided through the I-shaped member. As another example, in order to reduce the weight of the reinforcing portion 53 as much as possible so that fine adjustment of the operation of the molding machine can be performed more accurately, it is considered that the reinforcing portion 53 is provided in a truss type.

According to the above-described tube making method, each of the edge portions E at both lateral ends of the plate material P can be curved (C-shaped). Through this C molding, the sheet material has a substantially "C" shape in which both edges are folded.

Hereinafter, a molding machine according to an embodiment of the present invention (hereinafter referred to as a " main molding machine ") will be described. However, since the present molding machine is an apparatus that can be used in the present manufacturing method described above and is an invention including technical features equivalent to or equivalent to the present manufacturing method, the same or similar components as those described above are denoted by the same reference numerals And redundant description will be simplified or omitted.

3 to 5, the molding machine is a molding machine for bending the edge portion E of the plate material P, and is a molding machine in which the width direction of the plate material P in the lateral direction (E) of the transversely opposite ends of the plate material (P), and the upper surface and the lower surface of the lower edge A curved pressing portion 51 for pressing one or more curved pressing portions 51 and a curved pressing portion 51 for curving each of the edge portions E at both lateral ends of the plate material P, And a driving unit (not shown) for rotationally driving and linearly driving the body. Further, as described above, the molding machine 50 may include a control unit (not shown) for controlling the driving unit. In addition, the molding machine 50 may include a reinforcing portion 53 provided along the longitudinal direction on the outer upper surface and the outer lower surface so as to prevent deformation when the curved pressing portion 51 is pressed.

3, the closed loop 50a formed in the body of the present molding machine 50 may be formed in a " square " shape so as to surround each of the edge portions E at both ends of the plate material P. [

The molding machine 50 may include a heating unit (not shown) for heating the inside of the closed loop 50a. The heating section may be provided to perform low frequency induction heating. That is, the heating unit may be provided with a low-frequency heater. For example, the heating portion may be provided so that the induction coil is disposed on each surface thereof so that the edge portion E of the plate can be uniformly heated. The heating unit may be provided in at least one of the inside of the body of the molding machine 50 and the inside of the curved pressing portion 51.

The temperature at which the heating portion heats the edge portion E of the plate material P can be controlled to be A1 or lower, preferably 600 to 700 占 폚. If the heating temperature is lower than 600 ° C, the improvement in the formability due to heating is insufficient. If the heating temperature is higher than 700 ° C, there is a risk of phase change exceeding the A1 temperature. The heating unit may include a noncontact type temperature sensor to perform feedback control, but it is also possible to operate the heating unit for a predetermined time in consideration of the movement of the plate material P.

In addition, the heating unit may be a low-frequency induction heating unit as described above, but it is not limited thereto, and other heating means may be used.

The driving method for forming the C shape of the present molding machine 50 can be understood with reference to FIGS. 4 and 5, which has been described above with reference to the present method, and a detailed description thereof will be omitted.

Further, the edge portion (E) herein means a portion formed by the molding machine (C molding machine) according to the embodiment of the present application. It is preferable that the edge portion E is a portion corresponding to within 100 mm from an end portion in the lateral direction (width direction) of the plate material P which is a range where the temperature is raised by welding. When the width of the edge portion E exceeds 100 mm, the strength is lowered compared to the conventional method in which the steel sheet is not heated before C molding because it is out of the region heated by welding.

In addition, the present invention improves the moldability of the steel pipe when the temperature rises regardless of the type of the steel plate, so that the strength of the steel plate is not particularly limited, but the steel plate having a yield strength of 830 MPa or more, Since moldability can be ensured.

As described above, according to the present invention, it is possible to secure the expandability that enables the production of pipes of various sizes using one molding machine, and to reduce the area in which the molding machine is installed compared with the conventional molding machine An improved pipe making method and a molding machine can be provided. Further, according to the present invention, a steel pipe excellent in performance can be manufactured quickly and stably by simply integrating the heating and curving processes of both edge portions by using one molding machine.

Further, according to the present invention, it is possible to improve the picking angle? Without affecting the strength of the finished steel pipe (pipe), as compared with the case of molding a high-strength steel plate with a conventional molding method and / or a molding machine. Therefore, it is possible to prevent the steel pipe from being broken due to the concentration of stress in the welded portion due to the shortage of the picking angle during the pipe expanding process after welding, and the steel pipe can be produced more stably.

In addition, since the curved pressing portion 51 and the heating portion are provided together in the molding machine 50, the curving process can be continuously performed successively after the edge portion E is heated, and the process is simplified, Can proceed, and furthermore, higher moldability can be secured compared with the conventional mold, so that stable C molding can be achieved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the appended claims. It will be possible. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

50: Molding machine
50a: closed loop
51:
53:
P: sheet material
E: edge portion

Claims (10)

In a pipe making method,
(a) preparing a molding machine whose longitudinal cross-section forms a closed loop;
(b) curving the edge portion of the one end while moving the plate material such that an edge portion of one end in the transverse direction of the plate material passes through the closed loop;
(c) moving the plate through the closed loop until the molding machine reaches an edge of the other transversely opposite end of the plate;
(d) curving the edge of the other end while moving the plate so that the edge of the other end passes through the closed loop; And
(e) shaping the plate material curved at the edges at both ends into a pipe shape,
, ≪ / RTI &
Wherein the molding machine includes curved pressing portions provided on the upper and lower surfaces inside the closed loop for pressing at least one of the upper surface and the lower surface of each of the edge portions at both ends,
Wherein the molding machine in the step (b) and the step (d) is rotationally driven and linearly driven in correspondence with the movement of the plate material so that the curved pressing part can bend each of the edge parts at both ends, Way. The method according to claim 1,
Wherein the molding machine includes a heating portion for heating the inside of the closed loop,
In the step (b) and the step (d), the heating unit heats each of the edge parts at both ends corresponding to the movement of the plate material, and the curved pressing part presses the edge part heated by the heating part The method for bending a pipe. The method according to claim 1,
Wherein in the step (b) or (c), at least a part of the curvature pushing portion is in line contact with at least one of an upper surface and a lower surface of the edge portion. The method according to claim 1,
In the step (b)
The molding machine is set to a rotation state and a position state different from the molding machine of the step (a) so that the portion of the one edge portion that is pressed by the curvature pushing portion is continuously bent by a predetermined angle and passes through the closed loop Wherein the method comprises the steps of: The method according to claim 1,
In the step (d)
Wherein the molding machine is continuously rotationally driven and rectilinearly driven such that a curved path capable of curving the edge portion of the other end can be formed in combination with the movement of the plate material. The method according to claim 1,
Wherein the molding machine includes a reinforcing portion provided along the longitudinal direction on the outer upper surface and the outer lower surface so as to prevent deformation when the curved pressing portion is pressed. A molding machine for bending edge portions at both lateral ends of a plate material,
A body defining a closed loop through which one end of the plate material can pass;
A curved pressing portion provided on an upper surface and a lower surface of the inside of the closed loop for pressing at least one of upper and lower surfaces of the edge portions at both ends; And
And a driving unit for rotationally driving and linearly driving the body corresponding to the movement of the plate material so that the curvature-pressing unit can bend each of the edge portions at both ends. 8. The method of claim 7,
Wherein the closed loop is formed in a " square " shape to surround each of the edge portions at both ends. 8. The method of claim 7,
Further comprising a heating section for heating the inside of the closed loop. 8. The method of claim 7,
And a reinforcing portion provided along the longitudinal direction on the outer upper surface and the outer lower surface so as to prevent deformation when the curvature pressing portion is pressed.

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