JP5055938B2 - ERW pipe manufacturing equipment with good weld characteristics - Google Patents

Description

  The present invention relates to an apparatus for manufacturing a pipe that requires welded portion toughness such as for oil well line pipes or a pipe that requires welded portion strength such as a casing pipe for oil well.

  Usually, pipes are roughly classified into welded pipes and seamless pipes. Welded pipes are manufactured by rounding plates by roll forming etc. and welding by welding the width ends, as in the case of ERW steel pipes. Seamless pipes are made by drilling a lump of material at a high temperature, etc. Rolled to produce. In the case of a welded pipe, it is generally said that the properties of the welded part are inferior to that of the base metal, and in the application of the pipe, guarantees of toughness and strength of the welded part have always been discussed for each application.

  For example, in line pipes that transport crude oil, natural gas, etc., low temperature toughness is important because pipes are often laid in cold regions, and casing pipes that protect mining pipes are used in oil wells for crude oil mining. Needed, tube strength is valued.

    Among welded pipes, ERW pipes are welded without using weld metal, so the construction of the manufacturing apparatus is at least a device for supplying a strip, a device for correcting the shape of the supplied strip, and a correction. It consists of a device for roll-forming the strip, a device for inductively heating the roll-formed strip width end, and a device for pressure-contacting the induction-heated strip width end. Furthermore, in many cases, a device for heat-treating the welded portion of the welded tube and a device for adjusting the outer diameter shape of the tube are provided.

  In addition, the device for roll forming of the strip plate is a breakdown roll stand that bends the strip in a bow shape, a cage roll stand that rounds the strip bent in a bow shape into a tubular shape, and a fin pass molding that shapes the tube after being rolled. It consists of a stand.

  An example of such a conventionally used electric sewing tube manufacturing apparatus is shown in FIG. An uncoiler 1 that supplies the strip 20, a leveler 2 that straightens the strip 20, a roll forming machine 4 that gradually rounds the straightened strip 20, and both left and right width ends of the round strip 20 Induction heating device 5 for inductively heating the part, squeeze roll (electro-sealed welded part) 6 that presses the end of the width of the strip that has been induction heated to form pipe 21, and a bead part that cuts the weld bead part of pipe 21 The cutting machine 7, the sizer 8 for adjusting the outer diameter of the pipe 21 after cutting, and the pipe cutting machine 9 for cutting the pipe 21 having the adjusted outer diameter into a predetermined length. The roll forming machine 4 includes a predetermined number (two in this case) of fin pass forming stands 10 at the last stage. The fin shape is a one-step taper shape.

  In general, a hot-rolled sheet serving as a base material of a pipe is subjected to component design, heat treatment, and the like in consideration of the base material characteristics after the manufacture of the pipe, and characteristics such as toughness and strength of the base material are ensured.

  However, since the characteristics of the welded part are greatly influenced by the welding method more than the component design and heat treatment of the base metal, it is particularly important to develop a welding technique in the case of ERW welding.

  As a cause of poor ERW welding, the oxide generated at the width end of the welded strip called penetrator remains without being discharged from the end surface together with the molten steel during ERW welding, and this toughness is caused by this residual penetrator. There were many cases where the strength decreased and the strength was insufficient.

Therefore, conventionally, in order to remove the penetrator from the welded portion, a technique for actively discharging molten steel from the width end face of the welded strip at the welded portion has been intensively studied. For example, Patent Literature 1 and Patent Literature 2 describe examples in which the shape of the width end face of the strip is studied. Normally, the width end face of the strip is almost rectangular due to slits and end grinding, but this width end face is processed before electro-welding, and the processed wide end shape improves the discharge of molten steel during welding. The purpose is that.
JP-A-57-031485 Japanese Patent Laid-Open No. Sho 63-317212

  However, when the present inventors examined the method described in Patent Document 1, even if the amount of upset in the fin pass molding was significantly changed, only a part of the width end portion of the band plate 20 was used as the fin of the fin pass hole type roll. It turned out to be extremely difficult to contact. This is because the width end portion of the band plate 20 is only slightly hardened in the molding process so far, and the entire width end portion of the band plate is easily deformed along the fins, so that the fin portions are fully filled. This is because the shape of the fin is transferred to the width end of the strip. As a result, the width end portion of the strip 20 is not in a desired shape immediately before the electric resistance welding.

  Moreover, when the present inventors examined the method of patent document 2, the taper shape is provided to the whole width | variety edge part of the strip 20 using the edger roll 11 in the middle of roll shaping | molding (upstream side of a fin pass shaping | molding stand). Therefore, as described in Patent Document 2, since it is necessary to form using an edger roll whose diameter gradually increases from the pipe outer surface side to the pipe inner surface side, the width end portion on the pipe inner surface side is scraped off by the edger roll. Therefore, there is a problem that an extra material called “beard” is generated. Furthermore, since a large reaction force that opens the tubular band plate 20 to the outside acts in the cross-sectional direction of the band plate 20 to be roll-formed, the pressure between the edger roll 11 and the width end of the band plate 20 is inevitably small. Become. As a result, similarly to the above-mentioned Patent Document 1, it becomes difficult to work harden under the pressure of the width end portion by the edger roll, and even if the amount of upset is reduced by the subsequent fin pass molding, the band plate almost fills the fin portion, It was confirmed that it was difficult to give the shape as described in Patent Document 2 to the width end portion of the band plate 20.

  The present invention has been made in view of the above circumstances, and can make the shape of the width end portion immediately before ERW welding to be an appropriate shape, thereby sufficiently discharging molten steel during ERW welding. Thus, it is an object of the present invention to provide an electric welded tube manufacturing apparatus in which the penetrator can be reliably removed and an electric welded tube having good welded portion characteristics can be obtained.

As described above, in the prior art described in Patent Documents 1 and 2, in order to give a taper shape to the width end surface of the band plate, a part of the width end portion of the band plate is pressed against the fin of the fin pass hole roll. However, according to the study by the present inventors, even if the fin pass hole type roll is not filled with the entire circumference of the band plate, the band plate is mounted on the fin pass hole type roll. When entering, it was grasped that the width end portion was strongly pressed by the fin and the width end portion was completely filled in the fin portion. That is, when the strip is inserted into the fin pass hole roll, the width end of the strip in contact with the fin and the width center portion (tubular bottom portion) of the strip located on the opposite side of 180 degrees Is a beam bending state, and the reaction force of the strip plate that tries to bend the cross section into an arc shape acts greatly, even if the strip plate does not fill the fin pass hole roll, the width end of the strip plate A large compressive force acts in the circumferential direction, and as a result, the width end of the strip is strongly pressed by the fin, and the shape of the fin is transferred to the width end of the strip as it is.

  Therefore, the present inventors pay attention to the fact that the width end of the band plate is strongly pressed by the fin in the fin pass molding, and by actively utilizing this phenomenon, the taper has a predetermined taper at the width end of the band plate. Inspired by the method of giving shape. In other words, if the taper is provided with two or more stages of taper, the desired taper shape can be given to the width end of the strip even if the amount of upset in the fin pass molding is small. It has been found that the shape of the width end portion can be an appropriate taper shape.

  The present invention is based on the above idea and has the following features.

[1] At least a device for supplying a strip, a device for correcting the shape of the supplied strip, a device for roll-forming the corrected strip, and guiding the roll-formed strip width end An apparatus for manufacturing an electric resistance welded tube comprising an apparatus for heating and an apparatus for press-contacting an induction-heated strip width end, wherein the roll forming apparatus incorporates a fin having a two-stage taper shape. together have a fin pass forming apparatus having a final stand comprising incorporating fins having front stand and two-stage tapered, each tapered fin having a 2-step tapered shape of the front stand and a final stand A band which is inclined toward the center of the fin from the vertical direction toward the tip of the fin , and which is the inner diameter side of the tube at the front stand of the fin path molding by the fin path molding device. A taper shape is imparted to the plate width end portion, and a taper shape is imparted to the strip width end portion on the outer diameter side of the pipe in the final stand of the fin pass molding. The angle from the direction vertical end face is 25 ° to 50 °, and the length in the thickness direction from the taper start position to the end position is 20% to 40% (however, excluding 20%). An apparatus for producing an ERW pipe for a line pipe or a casing having a good welded part characteristic in which the absorbed energy at −46 ° C. at the weld wall thickness center position is 125 J or more and the brittle fracture surface ratio is 35% or less.

  In the present invention, an electric resistance welded tube having remarkably good toughness and weld strength can be produced.

  Embodiments of the present invention are described below.

(First embodiment)
FIG. 1 shows a basic configuration of an electric resistance welded tube manufacturing apparatus according to a first embodiment which is a reference of the present invention. The basic configuration of this electric sewing tube manufacturing apparatus includes an uncoiler 1 that supplies a belt plate 20, a leveler 2 that straightens the belt plate 20, and a roll forming machine 4 that gradually rounds the straightened belt plate 20. An induction heating device 5 that induction-heats the left and right width ends of the rolled strip 20, a squeeze roll (electrically welded portion) 6 that presses the induction-heated strip width end to form a pipe 21, and A bead part cutting machine 7 for cutting the weld bead part of the pipe 21, a sizer 8 for adjusting the outer diameter of the pipe 21 after cutting, and a pipe cutting machine 9 for cutting the pipe 21 having the adjusted outer diameter into a predetermined length. It is made up of. The roll forming machine 4 includes a predetermined number (two in this case) of fin pass forming stands 4 at the last stage.

  In the ERW pipe manufacturing apparatus according to this embodiment, the fins of the fin path forming first stand 3a have a normal one-step taper shape. FIG. 2 (a) is a cross-sectional view, and FIG. ), The fin of the second stand 3b has a two-step taper shape (second-step taper inclination angle α, second-step inclination portion vertical length β), By transferring the shape to the left and right width end portions of the band plate 20, as shown in FIG. 2 (c), a predetermined taper shape (from the width end surface to the tube outer surface is formed on the left and right width end portions on the side that becomes the tube outer surface. An inclination angle α toward the surface to be formed and a plate thickness direction distance β) from the surface serving as the outer surface of the tube at the start position at the width end surface are provided.

  And about the taper shape provided to the right-and-left both width | variety edge part of the strip 20, the angle from the plate | board thickness direction perpendicular | vertical end surface (inclination angle toward the surface used as the pipe outer surface from the width end surface of the strip 20) (alpha) is 25. The length in the plate thickness direction from the taper start position to the end position (the distance in the tape plate thickness direction between the taper start position on the width end face and the surface serving as the tube outer surface) β is the band plate thickness. Of 20% to 40%.

  This is because if the inclination angle α is less than 25 °, the molten steel is not sufficiently discharged from the central portion of the strip plate thickness, the penetrator remains and becomes defective, and the toughness and strength after ERW welding are reduced. If the angle α exceeds 50 degrees, the taper shape remains as a wrinkle of the tube of the product even after the electric resistance welding, which is a problem. Further, if the taper start distance β is less than 20% with respect to the plate thickness, the molten steel discharge at the center portion of the plate thickness becomes insufficient and the penetrator tends to remain, and the taper start distance β is 40% of the plate thickness. If it exceeds 50%, the taper shape remains as a flaw of the pipe of the product even after ERW welding, which is a problem.

  As described above, in this embodiment, the fin shape of the fin pass molding final stand 3b has a shape having a two-stage angle, and the fin shape is transferred to the left and right width end portions of the band plate 20. Therefore, the shape of the width end portion of the band plate 20 immediately before the ERW welding can be set to an appropriate tapered shape. As a result, a sufficient amount of molten steel is discharged at the time of electric resistance welding, and the penetrator is surely removed, so that an electric resistance welded tube with good welded portion characteristics can be obtained.

  In addition, in the above, a predetermined taper shape can also be given to the right-and-left both width | variety edge part used as a pipe inner surface side by changing a taper shape of two steps.

The basic configuration of the electric resistance welded tube manufacturing apparatus according to the second embodiment which is a reference of the present invention is also shown in the above-described figure.

  And in the electric resistance welded tube manufacturing apparatus according to the second embodiment, the fins of the fin-pass molding first stand 3a have a normal one-step taper shape. FIG. As shown in FIG. 3 (b), the fins of the second stand 3b have a three-stage taper shape (vertical length δ at the first step, second taper inclination angle γ, third step) 3), and by transferring the shape to the left and right width ends of the band plate 20, as shown in FIG. Predetermined taper shape at both the left and right width ends on the tube outer surface side (inclination angle α from the width end surface to the surface serving as the tube outer surface, distance in the plate thickness direction from the surface serving as the tube outer surface at the starting position at the width end surface β) and a predetermined taper shape (width end face or not) on both the left and right width ends on the tube inner surface side The inclination angle γ towards the surface to be inner surface, so as to impart a thickness direction distance [psi) from the surface of the inner surface of the starting position in the width end face. However, if one of the three fin angles is larger than the vertical direction of the fin pass roll, the width end of the strip is scraped off by the fins, resulting in a surplus material called “beard”. Since fins are formed at the time of forming the fin path and sparks of ERW welding are caused, the angle of the fin is preferably set to be equal to or less than the vertical direction.

  And about the taper shape provided to the both right and left width end portions of the band plate 20, the inclination angle α from the width end surface of the band plate 20 toward the surface serving as the tube outer surface and the angle of inclination toward the surface serving as the tube inner surface. γ is 25 ° to 50 °, and the distance β in the strip thickness direction between the taper starting position on the width end face and the surface serving as the pipe outer surface and the distance ψ in the strip thickness direction between the surface serving as the pipe inner surface and Each of them is set to 20% to 40% of the thickness of the strip plate.

  The reason is that if the inclination angles α and γ are less than 25 °, the molten steel discharge from the central portion of the strip plate thickness becomes insufficient, the penetrator remains and becomes defective, and the toughness and strength after ERW welding decrease. If the inclination angles α and γ exceed 50 degrees, the taper shape remains as a wrinkle of the tube of the product even after the electric resistance welding. Further, if the taper starting distances β and ψ are less than 20% of the plate thickness, the molten steel discharge at the central portion of the plate thickness is insufficient and the penetrator tends to remain, and the taper starting distances β and ψ are the plate thickness. On the other hand, if it exceeds 40%, the taper shape remains as a wrinkle of the tube of the product even after the ERW welding, which is a problem.

  As described above, in this embodiment, the fin shape of the fin-pass molding final stand 3b has a shape having three-step angles, and the fin shape is transferred to the left and right width end portions of the band plate 20. Therefore, the shape of the width end portion of the band plate 20 immediately before the ERW welding can be set to an appropriate tapered shape. As a result, a sufficient amount of molten steel is discharged at the time of electric resistance welding, and the penetrator is surely removed, so that an electric resistance welded tube with good welded portion characteristics can be obtained.

(Third embodiment)
The basic structure of the electric resistance welded tube manufacturing apparatus according to the third embodiment of the present invention is also shown in FIG.

  And the electric resistance welded tube manufacturing apparatus according to the third embodiment is shown in FIG. 4 (a) as a cross-sectional view, and FIG. 4 (b) shows a partial detailed view thereof. The fin has a two-stage taper shape (vertical length δ at the first step, second taper inclination angle γ), and the shape is transferred to the left and right width end portions of the band plate 20. As shown in FIG. 4 (c), the left and right width end portions on the tube inner surface side have predetermined taper shapes (inclination angle γ from the width end surface toward the tube inner surface, the start position on the width end surface The thickness of the second stand 3b in the rear stage is shown in FIG. 4 (d) and a partial detail view thereof in FIG. 4 (e). The fin has a two-step taper shape (taper inclination angle α in the second step, vertical length β in the second step) By transferring the shape to the left and right width end portions of the band plate 20, as shown in FIG. 4 (f), a predetermined taper shape (width end surface) is formed on the left and right width end portions on the tube outer surface side. To the surface which becomes the outer surface of the tube, and the plate thickness direction distance β) from the surface which becomes the outer surface of the tube at the start position at the width end surface.

  By the way, when the taper shape is given to the width end part which becomes the inner surface of the pipe by the fin pass molding first stand 3a, the portion is remarkably processed and hardened by strong pressure. Therefore, even if the taper shape is given by the fin pass molding second stand 3b, The taper shape provided by the first stand 3a is relatively difficult to collapse. Therefore, a predetermined taper shape can be given to the width end portion of the strip after completion of the fin pass molding on both the tube inner surface side and the tube outer surface side.

  And about the taper shape provided to the both right and left width end portions of the band plate 20, the inclination angle α from the width end surface of the band plate 20 toward the surface serving as the tube outer surface and the angle of inclination toward the surface serving as the tube inner surface. γ is 25 ° to 50 °, and the distance β in the strip thickness direction between the taper starting position on the width end face and the surface serving as the pipe outer surface and the distance ψ in the strip thickness direction between the surface serving as the pipe inner surface and Each of them is set to 20% to 40% of the thickness of the strip plate.

  The reason is that if the inclination angles α and γ are less than 25 °, the molten steel discharge from the central portion of the strip plate thickness becomes insufficient, the penetrator remains and becomes defective, and the toughness and strength after ERW welding decrease. If the inclination angles α and γ exceed 50 degrees, the taper shape remains as a wrinkle of the tube of the product even after the electric resistance welding. Further, if the taper starting distances β and ψ are less than 20% of the plate thickness, the molten steel discharge at the central portion of the plate thickness is insufficient and the penetrator tends to remain, and the taper starting distances β and ψ are the plate thickness. On the other hand, if it exceeds 40%, the taper shape remains as a wrinkle of the tube of the product even after the ERW welding, which is a problem.

  As described above, in this embodiment, in the fin pass pressure, the fin shape of the first stand 3a at the front stage and the fin shape of the second stand 3b at the rear stage are each formed into a shape having two-stage angles, and those fin shapes Is transferred to both the left and right width end portions of the band plate 20, the width end portion shape of the band plate 20 immediately before the ERW welding can be made into an appropriate taper shape. As a result, a sufficient amount of molten steel is discharged at the time of electric resistance welding, and the penetrator is surely removed, so that an electric resistance welded tube with good welded portion characteristics can be obtained.

  In the first to third embodiments described above, a tapered shape is applied to the tube outer surface side or the tube outer surface side width end of the band plate in the final fin-pass molding stand (here, the second stand 3b). The reason for this is that since the electric resistance welding is performed immediately after that, it is possible to perform the electric resistance welding while maintaining a good taper shape. However, a taper shape may be imparted to the width end portion of the band plate at the fin-pass molding start stand or the intermediate stand, and the taper shape may not be imparted to the final fin-pass molding stand. Once a taper shape is applied to the width end of the strip, the width end surface is markedly hardened by strong pressure, so the taper shape is relatively difficult to collapse even after fin pass molding. The state to which the shape is imparted can be maintained.

  Hereinafter, a description will be given based on examples.

  Here, an electric resistance welded tube of φ600 was manufactured using a strip (steel strip) having a plate width of 1920 mm × 19.1 tmm. And the test piece was cut out from the weld part of the manufactured ERW pipe, the Charpy test was done, and the performance was evaluated. Each Charpy test piece is taken from 10 points with different pipe longitudinal directions, the specimen length direction is parallel to the pipe circumferential direction, the notch length center is taken as the weld thickness center position, and 2 mmV of JIS5 An impact test at −46 ° C. was performed as a notch impact test piece, and the absorbed energy and the brittle fracture surface ratio were measured. In addition, the absorbed energy was 125 J or more and the brittle fracture surface ratio was 35% or less as the allowable performance range.

( Reference Example ) As a reference example , the above-mentioned electric resistance welded tube was manufactured using the electric resistance welded tube manufacturing apparatus according to the second embodiment described above. The inclination angle α on the tube outer surface side and the inclination angle γ on the tube inner surface side were both 25 °.

  (Conventional example) As a conventional example, the above-mentioned electric resistance welded tube was manufactured using the conventional electric resistance welded tube manufacturing apparatus shown in FIG.

  Table 1 shows the results of measuring the Charpy impact value and the brittle fracture surface ratio at the welded portion of the electric resistance welded tube manufactured as described above. Also. The result of observing the shape at the width end portion of the strip end width just before ERW welding was cut out and collected.

From Table 1, in the reference example , the impact strength of the welded portion is high, the brittle fracture surface ratio is small, the toughness is good, and the reliability of the product is high. In comparison with this, in the conventional example, the impact strength of the welded portion was low, the brittle fracture surface ratio was large, the toughness was lowered, and the reliability of the product was poor.

It is a figure which shows the basic composition of the electric sewing tube manufacturing apparatus which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG . 1 is an explanatory view of an electric resistance welded tube manufacturing apparatus according to a first embodiment for reference of the present invention. It is explanatory drawing of the electric sewing tube manufacturing apparatus which concerns on 2nd Embodiment used as a reference of this invention. It is explanatory drawing of the electric sewing tube manufacturing apparatus which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the conventional electric sewing pipe manufacturing apparatus.

Explanation of symbols

1 Uncoiler 2 Leveler
3 Fin Pass Forming Stand 3a Fin Pass Forming First Stand 3b Fin Pass Forming Second Stand 4 Roll Forming Machine 5 Induction Heating Device 6 Squeeze Roll (Electro-Seam Welding Section)
7 Bead cutting tool 8 Sizer 9 Pipe cutting machine 10 Fin pass forming stand 20 Strip plate 21 Pipe

Claims (1)

At least a device for supplying a strip, a device for correcting the shape of the supplied strip, a device for roll-forming the corrected strip, and a device for induction heating the roll-formed strip width end And a device for press-fitting the induction-heated strip width end, wherein the roll forming device includes a front stand incorporating fins having a two-step tapered shape; A fin path forming apparatus having a final stand incorporating a fin having a two-step taper shape, and each taper of the fin having the two-step taper shape of the front stand and the final stand is a tip of the fin Is inclined toward the fin center side from the vertical direction toward the center , and the fin-pass forming device uses the fin- stand forming front stand to form the end of the strip that becomes the inner diameter side of the tube. In the final stand of the fin pass molding, a taper shape is given to the end portion of the width of the strip on the outer diameter side of the tube, and the taper shape is from the vertical end surface in the plate thickness direction. Characterized in that the angle in the plate thickness direction is 25 ° to 50 °, and the length in the plate thickness direction from the taper start position to the end position is 20% to 40% (excluding 20%) of the plate thickness. An electro-resistance tube manufacturing apparatus for line pipes or casings with good welded properties, wherein the absorbed energy at -46 ° C at the center of the wall thickness is 125 J or more and the brittle fracture surface ratio is 35% or less.

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