JP4720479B2 - High-efficiency manufacturing method for ERW pipes with good weld characteristics - Google Patents

Description

  The present invention relates to a high-efficiency manufacturing method for an electric resistance welded pipe having good weld characteristics, and in particular, a welded part such as a pipe for an oil well line pipe that requires toughness or a casing pipe of an oil well is required. The present invention relates to a manufacturing method capable of manufacturing a pipe to be manufactured with high efficiency in response to a change in product dimensions.

  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.

  Usually, a hot-rolled sheet that is 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 pipe is manufactured, and characteristics such as toughness and strength of the base material are secured.

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

Therefore, conventionally, in order to remove the penetrator, which is the main cause of poor ERW welding, from the welded portion, a technique for positively discharging molten steel from the width end face of the welded strip 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 welded band material is examined. In other words, the left and right width end faces of the welded band material are generally rectangular due to slits and end grinding, but the upper and lower surface sides of the left and right width end faces are respectively tapered before roll forming. It aims at making molten steel discharge | emission favorable at the time of ERW welding with the width | variety edge part shape which processed and taper-processed.
JP 2001-17079A JP 2003-164909 A

  However, in the conventional methods described in Patent Documents 1 and 2 described above, only a perforated rolling roll, a cutting tool, and a grinding roll are listed as taper processing means. There are various problems in applying to the manufacturing process of a sewing tube, and further detailed examination is necessary.

  That is, in the actual ERW pipe manufacturing process, strips of various thicknesses are made into ERW pipes. For example, when taper shapes are given to the left and right width ends of a strip using a perforated rolling roll However, since different hole rolling rolls must be prepared for each strip thickness and replaced with the hole rolling roll, the production efficiency of the tube is lowered, which is a problem. In addition, when using cutting tools and grinding rolls, the positional relationship between the cutting tools and grinding rolls that taper the upper and lower surfaces of the left and right width ends of the strip is shown for each strip thickness. Therefore, it takes time to make adjustments, and the production efficiency of the tube has been significantly reduced.

  The present invention has been made in view of the circumstances as described above, and even if the thickness of the strip is changed, an appropriate taper shape is imparted to the left and right width end portions of the strip before the ERW welding. An object of the present invention is to provide a high-efficiency manufacturing method for an electric resistance welded tube with good welded portion characteristics, which can maintain good welding quality and also suppress a decrease in manufacturing efficiency.

  As a result of earnestly examining the method of imparting an appropriate taper shape to the width end of the band without reducing the production efficiency even when the thickness of the band changes, the present inventors have determined the width of the end of the band. It came to the mind that it is good to give a taper shape separately with respect to the upper surface side and the lower surface side over time.

  That is, for the upper surface side and the lower surface side of the width end surface of the band material, and simultaneously giving a tapered shape, as described above, replacing the perforated rolling roll for each plate thickness of the band material, It is necessary to set the positional relationship between the cutting tool and the grinding roll with accuracy over time, and this reduces the manufacturing efficiency, but after giving a tapered shape to the width end on one surface side, wait for a while. If a taper shape is applied to the width end on the other surface side, even if the plate thickness changes variously, it is only necessary to finely adjust the vertical position of the device that applies the respective taper shape. Is not reduced.

  And in order to give a taper shape to the width end part of one surface side of a strip, a taper shape is given by cutting or grinding before roll forming, and a taper shape is given to the width end part of the other surface side. For this, it is preferable to provide a taper shape by fin pass forming during roll forming.

  This is because the strip material is almost flat on the roll forming entry side, so that the taper shape can be easily given by cutting and grinding, and the device for providing the taper shape by cutting and grinding is relatively large. This is because an installation space is required, and it is difficult to install because the interval between the width end portions of the band material is narrowed during or after roll forming. Therefore, in order to give a taper shape to the width end portion on one surface side of the strip, it is preferable to perform cutting or grinding before roll forming.

  In addition, in the fin pass forming during roll forming, since the band material is filled in the fin pass roll, the width end portion of the band material is strongly pressed. Therefore, in this fin pass forming, a desired fin shape is formed in the width end portion of the band material. It is preferable to give a taper shape to the width end portion on the other surface side of the band material by transferring.

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

[1] The strip is roll-formed so that the upper surface of the strip becomes the inner surface of the tube and the lower surface of the strip becomes the outer surface of the tube, the width ends are butted together, and electro-welded to obtain a tube. In the method of manufacturing an electric resistance tube,
A taper shape is individually given to the upper surface side and the lower surface side of the width end portion of the band material before ERW welding,
A cutting tool or roll-shaped grinding wheel with a cutting blade arranged in a roll shape that finely adjusts the height position according to the change in the thickness of the strip material on the upper surface side of the width end of the band material before roll forming In addition to providing a taper shape by using, the taper shape is given to the lower surface side of the width end portion of the band material by fin path molding during roll molding,
The cutting surface of the cutting tool in which the cutting blade is arranged in a roll shape or the grinding surface of a roll-shaped grinding wheel is a shape in which a portion parallel to the roll axis and a portion inclined outward with respect to the roll axis are connected,
When a taper shape is given by the fin pass molding, the final stand of the fin pass molding stand is a stand having a fin shape having a two-step taper, and the final stand having the fin shape having the two-step taper is tapered. Give shape,
The taper shape has an inclination angle of 25 ° to 50 ° from the width end surface to the upper surface and the lower surface of the band member, and the taper starting position at the width end surface of the band member and the band member between the upper surface and the lower surface A high-efficiency manufacturing method of an electric resistance welded tube with good welded portion characteristics, characterized in that the distance in the plate thickness direction is 20% to 40% of the strip thickness .

  In the present invention, it is possible to give an appropriate taper shape to the left and right width end portions of the band material before ERW welding in response to a change in the plate thickness of the band material, so that the welding quality is improved. Since it can hold | maintain and the fall of manufacturing efficiency can also be suppressed, it is possible to manufacture an electric resistance welded tube with the favorable welded part characteristic at high efficiency.

  Embodiments of the present invention are described below.

(First embodiment)
FIG. 1 shows an ERW pipe manufacturing line used in the first embodiment which is a reference of the present invention. In this electric sewing tube manufacturing line, the strip 20 is discharged from the uncoiler 1, straightened by the leveler 2, and gradually rolled up by the roll forming machine 5. The end portion is electro-welded with an electric seam welding machine including an induction heating unit 6 and a squeeze roll (electro-sealed welding part) 7 to form a pipe 30, and the weld bead part of the pipe 30 is cut with a bead part cutting machine 8. The tube 30 after cutting is adjusted in outer diameter by the sizer 9 and then cut to a predetermined length by the tube cutting machine 10. The roll forming machine 5 includes a predetermined number (two in this case) of fin pass forming stands 4 at the last stage.

  In this embodiment, in addition to the basic configuration described above, cutting or grinding is performed between the leveler 2 and the roll forming machine 5 to give tapered shapes to the left and right width end portions on the upper surface side of the strip 20. Means 3 are provided. The cutting or grinding means 3 is shown in FIG. 2 as viewed in the direction of arrows A-A in FIG. 1, and as shown in FIG. a)) or a roll-shaped grinding wheel 3b (FIG. 3B) is rotated by a motor 3e, and its cutting surface or grinding surface is parallel to the roll axis. A pair of left and right are arranged in the width direction of the band member 20 and each roll axis is inclined at a predetermined angle α from the vertical direction, whereby a predetermined taper shape (width) is formed at the left and right width end portions on the upper surface side of the band member 20. An inclination angle α from the end surface toward the upper surface and a plate thickness direction distance β) from the upper surface of the starting position at the width end surface are provided. Hereinafter, the cutting tool 3a in which the cutting blades are arranged in a roll shape will be referred to as a cutting roll 3a, and the roll-shaped grinding wheel 3b will be referred to as a grinding roll 3b.

  Furthermore, in this embodiment, the final stand 4a of the fin pass forming stand 4 is shown in FIG. 4 (a) as seen from the arrow BB in FIG. 1 and in FIG. 4 (b). A fin shape having a two-step taper (second-step taper inclination angle α, second-step inclined portion vertical length β) is provided, and the shape is transferred to the width end portion of the band member 20. The taper 20 has a predetermined taper shape at the left and right width ends on the lower surface side (outer surface side of the tube 30) (inclination angle α from the width end surface toward the lower surface, from the lower surface of the starting position on the width end surface). The sheet thickness direction distance β) is given.

  In the ERW pipe manufacturing line configured as described above, when the strips 20 having different thicknesses are continuously passed through, the left and right width end portions on the upper surface side and the lower surface side for each strip member 20. When a predetermined taper shape is applied to the belt 20, the cutting roll 3 a or the grinding roll 3 b is inclined by a predetermined angle α, and the height direction position thereof is finely adjusted so that the left and right width ends on the upper surface side of the strip 20 By cutting or grinding the portion, a predetermined taper shape is given to the left and right width end portions on the upper surface side of the band member 20, and both the left and right sides on the lower surface side of the band member 20 in the final stand 4a of the fin pass molding. By transferring the fin shape to the width end portion, a predetermined taper shape is imparted to the left and right width end portions on the lower surface side of the band member 20. As a result, there is no need to replace the perforated rolling roll for each sheet thickness of the strip or to set the positional relationship such as the cutting tool over a long period of time as in the prior art, thus reducing the production efficiency. Without predetermined | prescribed, a predetermined taper shape can be provided to the right-and-left both width | variety edge part of the strip | belt material 20 according to board thickness.

  As described above, in this embodiment, an appropriate taper shape can be imparted to the left and right width end portions of the band material 20 before the ERW welding in a flexible manner corresponding to the change in the plate thickness of the band material 20. Therefore, it is possible to maintain the welding quality satisfactorily and to suppress a decrease in manufacturing efficiency, and it is possible to manufacture an electric resistance welded tube with good welded portion characteristics with high efficiency.

  In addition, about the taper shape provided to the both left and right width end portions of the band member 20, the inclination angle α from the width end surface of the band member 20 toward the upper surface or the lower surface is 25 ° to 50 °, The taper starting position on the width end surface and the distance β from the upper surface or the lower surface are preferably 20% to 40% of the strip thickness.

That is, if the inclination angle α is less than 25 °, the molten steel discharge from the central part of the strip thickness becomes insufficient, the penetrator remains and becomes defective, and the toughness and strength after ERW welding decrease, and the inclination If the angle α exceeds 50 ° , the taper shape remains as a wrinkle of the pipe of the product even after the ERW welding, which is a problem. Further, when the 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 when the distance β exceeds 40% with respect to the plate thickness. Even after ERW welding, the taper shape remains as a flaw in the tube of the product, which is a problem.

  In addition, in this embodiment, separately from the cutting or grinding means 3 for imparting a taper shape to the left and right width end portions on the upper surface side of the band member 20, if necessary, on the upstream side of the band member Cutting or grinding means for cutting or grinding both left and right width end portions substantially parallel to the width end surface 20 can be provided so that the width end surface of the band member 20 can be smoothed in advance.

(Second Embodiment)
FIG. 5 shows an ERW pipe production line used in the second embodiment of the present invention. This ERW pipe production line is substantially the same as the ERW pipe production line used in the first embodiment described above, but the upper surface of the band member 20 disposed between the leveler 2 and the roll forming machine 5. The cutting or grinding means 3 for giving a taper shape to the left and right width end portions on the side is different.

  That is, the cutting or grinding means 3 is a cutting tool in which cutting blades are arranged in a roll shape as shown in FIG. 6 as viewed in the direction of arrows CC in FIG. 5 and in FIG. The cutting tool 3c (FIG. 7 (a)) having a shape in which the cutting surface is substantially parallel to the roll axis and the portion inclined outward with respect to the roll axis is a roll-shaped grinding wheel. Thus, the grinding wheel 3d (FIG. 7B) has a shape in which the ground surface is connected to a portion parallel to the roll axis and a portion inclined outward with respect to the roll axis. Hereinafter, the cutting tool 3c is referred to as a tapered cutting roll 3c, and the grinding wheel 3d is referred to as a tapered grinding roll 3d.

  By using the cutting roll 3c or the grinding roll 3d having such a shape, the same cutting roll 3c or the grinding roll 3d allows the strip material having various thicknesses to be fixed on the upper surface side of the width end portion thereof. It becomes easy to give the Taber shape of an angle and a position.

  In addition, in order to give a taber shape to the lower surface side of the width end portion of the band member 10, the final stand 4a of the fin pass forming stand 4 is shown in FIG. As shown in FIG. 8 (b), a partial detail view is shown in FIG. 8 (b), and a two-step taper (taper inclination angle α of the second step, vertical length β of the inclined portion of the second step) A fin shape is provided, and the shape is transferred to the width end portion of the band member 20, so that a predetermined width is formed at the left and right width end portions on the lower surface side (outer surface side of the tube 30) of the band member 20. A tapered shape is provided.

  Therefore, also in this embodiment, it is possible to give an appropriate taper shape to both the left and right width end portions of the band material 20 before the ERW welding in a flexible manner corresponding to the change in the plate thickness of the band material 20. Since the welding quality can be maintained well and the decrease in manufacturing efficiency can be suppressed, it is possible to manufacture an electric resistance welded tube with good welded portion characteristics with high efficiency.

  In the above-described first and second embodiments, the upper surface side and the lower surface side of the band material are provided with a taber shape that is symmetric with respect to the plate thickness center plane. A taber shape in which the upper surface side and the lower surface side of the material are asymmetric with respect to the plate thickness center plane may be provided.

  In the case of a production line shown in FIG. 1 or 4 in which the forming direction of the strip is reversed upside down (that is, the upper surface of the strip is the outer surface of the pipe), The taper shape may be given to the width end portion on the lower surface side of the strip by grinding, and the taper shape may be given to the width end portion on the upper surface side of the strip by fin pass molding.

  Hereinafter, a description will be given based on examples.

  Here, an ERW pipe of φ600 is manufactured using a strip (steel strip) having a plate width of 1920 mm × 19.1 tmm, and subsequently, using a strip (steel strip) having a plate width of 1920 mm × 11.3 tmm. , Φ600 electric resistance welded tube was manufactured.

  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 1 ) As Reference Example 1 , the above-described electric resistance welded tube was manufactured based on the first embodiment described above. At that time, the cutting roll 3a shown in FIG. 3A was used as the cutting or grinding means 3 for imparting a taper shape to the left and right width end portions on the upper surface side of the strip. Further, the inclination angles α of the tapered shapes on the upper surface side and the lower surface side were both 30 °. When the strip thickness was changed from 19.1 tmm to 11.3 tmm, the vertical position of the cutting roll 3a was moved downward by 7.8 mm to make fine adjustments.

( Reference Example 2 ) As Reference Example 2 , the above-described electric resistance welded tube was manufactured based on the first embodiment described above. At that time, the grinding roll 3b shown in FIG. 3 (b) was used as the cutting or grinding means 3 for imparting a taper shape to the left and right width end portions on the upper surface side of the strip. Further, the inclination angles α of the tapered shapes on the upper surface side and the lower surface side were both 40 °. When the strip thickness was changed from 19.1 tmm to 11.3 tmm, the vertical position of the grinding roll 3b was moved 7.8 mm downward and finely adjusted.

  (Invention Example 3) As Invention Example 3, the above-described electric resistance welded tube was manufactured based on the second embodiment described above. At that time, a tapered cutting roll 3c shown in FIG. 7A was used as a cutting or grinding means 3 for imparting a taper shape to the left and right width end portions on the upper surface side of the strip. Further, the inclination angles α of the tapered shapes on the upper surface side and the lower surface side were both 30 °. In addition, when the plate | board thickness of the strip | belt material changed from 19.1 tmm to 11.3 tmm, the up-and-down position of the tapered cutting roll 3c was moved 7.8 mm below, and was finely adjusted.

  (Invention Example 4) As Invention Example 4, the above-mentioned electric resistance welded tube was manufactured based on the second embodiment described above. At that time, a tapered grinding roll 3d shown in FIG. 7B was used as a cutting or grinding means 3 for imparting a taper shape to the left and right width end portions on the upper surface side of the strip. Further, the inclination angles α of the tapered shapes on the upper surface side and the lower surface side were both 40 °. In addition, when the plate | board thickness of the strip | belt material changed from 19.1 tmm to 11.3 tmm, the up-and-down position of the taper grinding roll 3d was moved 7.8 mm below, and was finely adjusted.

  (Comparative Example) As a comparative example, in the production line shown in FIG. 1, a perforated rolling roll is provided between the leveler 2 and the roll forming machine 5, and the upper surface side and the lower surface of the strip material are provided by the perforated rolling roll. The above-mentioned electric resistance welded tube was manufactured by giving a tapered shape to the left and right width end portions on the side. The inclination angles α of the tapered shapes on the upper surface side and the lower surface side were both 30 °. Incidentally, at that time, the cutting or grinding means 3 was removed, and the fin shape of the final stand 4a of the fin pass molding was also made a conventional one-step taper. When the thickness of the strip was changed from 19.1 tmm to 11.3 tmm, the production line was temporarily stopped, and the above-mentioned perforated rolling roll was changed from 19.1 tmm to 11.3 mmt.

  (Conventional example) As a conventional example, in the production line shown in FIG. 1, the left and right width end surfaces of the band material were polished smoothly between the leveler 2 and the roll forming machine 5 to produce the above-described electric sewing tube. . Incidentally, at that time, the cutting or grinding means 3 was removed, and the fin shape of the final stand 4a of the fin pass molding was also made a conventional one-step taper. Even when the strip thickness was changed from 19.1 tmm to 11.3 tmm, the production was continued without stopping the production line.

  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. Moreover, the manufacturing efficiency of the comparative example was set to 1, and the ratio of the manufacturing efficiency of each example to that was shown in the same table.

From Table 1, the ERW pipes according to Reference Examples 1 and 2 and Invention Examples 3 and 4 have high impact strength at the welded portion, low brittle fracture surface ratio, good toughness, and high product reliability. . On the other hand, the ERW pipe according to the conventional example has a low impact strength at the welded portion, a high brittle fracture surface ratio, a low toughness, and poor product reliability. Further, in Reference Examples 1 and 2 and Invention Examples 3 and 4 , the production efficiency is remarkably improved as compared with the comparative example.

  Therefore, it was confirmed that the ERW pipe having good welded portion characteristics can be manufactured with high efficiency by the present invention.

It is explanatory drawing of the ERW pipe manufacturing line in 1st Embodiment to which this invention makes reference . It is an AA arrow line view of FIG. FIG. 3 is a partial detail view of FIG. 2. It is a BB arrow line view of FIG. It is explanatory drawing of the ERW pipe manufacturing line in the 2nd Embodiment of this invention. It is CC arrow line view of FIG. FIG. 7 is a partial detail view of FIG. 6. FIG. 6 is a DD arrow view of FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Uncoiler 2 Leveler 3 Cutting or grinding means 3a Cutting roll 3b Grinding roll 3c Cutting roll 3d Grinding roll 4 Fin pass forming stand 4a Final pass of fin pass forming 5 Roll forming machine 6 Induction heating device 7 Squeeze roll (electro-sewing weld)
8 Bead cutting tool 9 Sizer 10 Pipe cutting machine 20 Band material 30 Pipe

Claims (1)

An electric resistance welded tube that is formed by roll-forming the band material and butting the width ends together so that the upper surface of the belt material becomes the inner surface of the tube and the lower surface of the belt material becomes the outer surface of the tube. In the manufacturing method of
A taper shape is individually given to the upper surface side and the lower surface side of the width end portion of the band material before ERW welding,
A cutting tool or roll-shaped grinding wheel with a cutting blade arranged in a roll shape that finely adjusts the height position according to the change in the thickness of the strip material on the upper surface side of the width end of the band material before roll forming In addition to providing a taper shape by using, the taper shape is given to the lower surface side of the width end portion of the band material by fin path molding during roll molding,
The cutting surface of the cutting tool in which the cutting blade is arranged in a roll shape or the grinding surface of a roll-shaped grinding wheel is a shape in which a portion parallel to the roll axis and a portion inclined outward with respect to the roll axis are connected,
When a taper shape is given by the fin pass molding, the final stand of the fin pass molding stand is a stand having a fin shape having a two-step taper, and the final stand having the fin shape having the two-step taper is tapered. Give shape,
The taper shape has an inclination angle of 25 ° to 50 ° from the width end surface to the upper surface and the lower surface of the band material, and the band material between the taper start position on the width end surface of the band material and the upper surface and the lower surface. A high-efficiency manufacturing method of an electric resistance welded tube with good welded portion characteristics, characterized in that the distance in the plate thickness direction is 20% to 40% of the strip thickness.

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