Manufacturing method for pipe threaded joints

Abstract

To adjust misalignment of tubes joined together in the peripheral direction more accurately than conventionally.SOLUTION: A method for manufacturing a tube screw joint comprises: a step (step S1) of forming a box at one end of a first element tube having a first marking added to the outer peripheral surface; a step (step S3) of disposing a second element tube having a second marking added to the outer peripheral surface in a first lathe so as to set the second marking at a prescribed pin machining initial position and to form a trial pin on one end of the second element tube; a step (step S4) of fastening the box and a trial pin together to measure a misaligning amount α; and a step (step S5) of disposing a third element tube having a third marking added to the outer peripheral surface in the first lathe so as to set the third marking at the pin machining initial position, and forming a pin at one end of the third element tube by using a program having the rotation angle of the element tube offset by the misaligning amount α with respect to a program used for machining the trial pin.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a threaded joint for pipes. [Background technology]

[0002] In oil wells, natural gas wells, and the like (hereinafter collectively referred to as "oil wells"), casings are used to construct multiple stages of well walls and tubing is placed inside the casings to produce oil and gas in order to extract underground resources. These casings and tubing are made up of many steel pipes connected in series, and pipe threaded joints are used for connecting them. Steel pipes used in oil wells are also called oil country tubular goods.

[0003] Generally, the end of a male-threaded steel pipe is called a "pin" because it includes an element that is inserted into the end of a female-threaded steel pipe. The end of a female-threaded steel pipe is called a "box" because it includes an element that receives the end of a male-threaded steel pipe. Both pins and boxes are tubular because they are the ends of pipe materials.

[0004] When burying oil well tubular goods underground, cables are sometimes placed to supply power to oil pumps and other equipment. These cables are fixed to the surface of the tubular goods from the surface to the deepest part of the oil well. There are two methods for this fixation. The first is to attach the cable and fixing jig to the surface of the tubular goods at the same time as the tubular goods are lowered on the rig. The second is to attach only the cable fixing jig to the surface of the tubular goods in advance at the tubular goods storage facility (yard) rather than on the rig, and then attach the cable during the tubular goods lowering work on the rig.

[0005] The former requires more rig work time than the latter, but can be done with standard OCTG. The latter can shorten rig work time compared to the former, but the fixing jigs attached to each OCTG must all be aligned in a straight line after the pipes are lowered. In other words, to implement the latter method, the circumferential tightening position of the threaded joint must be controlled.

[0006] Japanese Patent Publication No. 4741497 discloses a method for manufacturing a cylindrical component having mutually oriented threaded elements. The method includes the steps of machining a first threaded element on one end of the component (step b) and machining a second threaded element on the other end (step d). The method further includes the steps of threading a first orientation gauge onto the first threaded element (step e), drawing an orientation mark on the outer periphery of the component that is axially aligned with the mark on the first orientation gauge (step f), threading a second orientation gauge onto the second threaded element (step g), and defining a starting position for machining a new second threaded element so as to be axially offset from the initial position by an amount determined as a function of the angle of deviation between the mark on the component and the mark on the second orientation gauge (step h).

[0007] JP 2003-525757 A discloses a method for assembling a pipe joint, which includes a machining step of machining a plurality of threads to a calculated depth in each of the pin members and each of the connecting members, so that the pin alignment mark and the connecting alignment mark are aligned when the pin members and the connecting members are in a fully joined position. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4741497 [Patent Document 2] Special Publication No. 2003-525757 Summary of the Invention [Problem to be solved by the invention]

[0009] In both of the methods described in Japanese Patent No. 4741497 and Japanese Translation of PCT International Publication No. 2003-525757, the circumferential misalignment between the joined pipes is adjusted by converting the circumferential misalignment of the fastening position into an axial offset and changing the length of the threads. However, the inventors have found that adjustment by axial offset may not accurately adjust the circumferential misalignment between the joined pipes.

[0010] An object of the present invention is to provide a method for manufacturing a threaded joint for pipes that can adjust the circumferential misalignment between joined pipes with greater accuracy than conventional methods. [Means for solving the problem]

[0011] A manufacturing method for a tubular threaded joint according to one embodiment of the present invention is a manufacturing method for a tubular threaded joint in which a tubular threaded joint is manufactured using one or more lathes that can be program-controlled by a computer, said tubular threaded joint comprising a tubular pin that is provided at the tip of a pipe, and a tubular box into which said pin is screwed and fastened to said pin, said pin having a male thread formed on the outer periphery of said pin, and said box having a female thread formed on the inner periphery of said box that mates with said male thread when fastened, said method comprising the steps of forming said box at one end of a first mother pipe that has a first marking provided on its outer periphery, and forming a tubular box at one end of a second mother pipe that has a second marking provided on its outer periphery. The method includes the steps of: placing a blank tube on a first lathe so that the second marking is at a predetermined pin machining initial position, and forming a prototype pin on one end of the second blank tube; fastening the box and the prototype pin together, and measuring a circumferential deviation α between the first marking and the second marking in the fastened state; and placing a third blank tube, which has a third marking on its outer peripheral surface, on the first lathe so that the third marking is at the pin machining initial position, and forming the pin on one end of the third blank tube using a program in which the rotation angle of the blank tube is offset by the deviation α from the program used to machine the prototype pin. [Effects of the Invention]

[0012] According to the present invention, the circumferential misalignment between joined pipes can be adjusted more accurately than ever before. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a plan view showing a schematic example of the configuration of a tubular threaded joint. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a flow diagram showing a method for manufacturing a tubular threaded joint according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic view illustrating a step of forming a box at one end of the first hollow shell. [Figure 5] FIG. 5 is a schematic view illustrating a step of forming a box at one end of the first hollow shell. [Figure 6] FIG. 6 is a schematic view illustrating a step of forming a second box at the other end of the first hollow shell. [Figure 7] FIG. 7 is a schematic view illustrating a step of forming a second box at the other end of the first hollow shell. [Figure 8] FIG. 8 is a schematic diagram for explaining a step of forming a prototype pin at one end of the second blank tube. [Figure 9] FIG. 9 is a schematic diagram for explaining a step of forming a prototype pin at one end of the second blank tube. [Figure 10] FIG. 10 is a schematic diagram for explaining the process of fastening a box and a prototype pin together and measuring the amount of circumferential deviation α between the first marking and the second marking in the fastened state. [Figure 11] FIG. 11 is a schematic view illustrating a step of forming a pin at one end of the third hollow shell. [Figure 12] FIG. 12 is a schematic view illustrating a step of forming a pin at one end of the third hollow shell. [Figure 13] FIG. 13 is a schematic view illustrating a step of forming a second pin at the other end of the third hollow shell. [Figure 14] FIG. 14 is a schematic view illustrating a step of forming a second pin at the other end of the third hollow shell. [Figure 15] FIG. 15 is a cross-sectional view that schematically shows the shape of the pin before and after the axial offset C is applied. [Figure 16] FIG. 16 is a diagram in which the cross-sectional profile of the pin before and after the axial offset C is applied is superimposed. [Figure 17] FIG. 17 is a flow diagram showing a method for manufacturing a tubular threaded joint according to the second embodiment of the present invention. [Figure 18] FIG. 18 is a schematic view for explaining the step of forming a second trial pin at the other end of the second mother tube. [Figure 19] FIG. 19 is a schematic view for explaining the step of forming a second trial pin at the other end of the second mother tube. [Figure 20] FIG. 20 is a schematic diagram for explaining a process of fastening the box and the second trial pin and measuring the amount of deviation β in the circumferential direction between the first marking and the second marking in the fastened state. [Figure 21] FIG. 21 is a schematic view illustrating a step of forming a second pin at the other end of the third hollow shell. [Figure 22] FIG. 22 is a schematic view illustrating a step of forming a second pin at the other end of the third hollow shell. [Figure 23] FIG. 23 is a flow diagram showing a method for manufacturing a tubular threaded joint according to the third embodiment of the present invention. [Figure 24] FIG. 24 is a schematic diagram for explaining the step of taking a marking gauge from the third hollow shell. [Figure 25] FIG. 25 is a schematic diagram illustrating a process of forming a trial box on the fourth blank tube. [Figure 26] FIG. 26 is a schematic diagram for explaining a process of fastening the marking gauge to the prototype box and measuring the amount of circumferential deviation γ between the third marking and the fourth marking in the fastened state. [Figure 27] FIG. 27 is a schematic diagram illustrating the step of forming a box on the fifth tube shell. DETAILED DESCRIPTION OF THE INVENTION

[0014] A method for manufacturing a tubular threaded joint according to one embodiment of the present invention is a method for manufacturing a tubular threaded joint using one or more lathes capable of computer program control. The tubular threaded joint comprises a tubular pin provided at the tip of the pipe, and a tubular box into which the pin is screwed and fastened. The pin has a male thread formed on its outer periphery, and the box has a female thread formed on its inner periphery that mates with the male thread when fastened. A method for manufacturing a tubular threaded joint comprises the steps of: forming a box at one end of a first mother pipe having a first marking on its outer circumferential surface; placing a second mother pipe having a second marking on its outer circumferential surface on a first lathe so that the second marking is in a predetermined initial position for pin machining, and forming a prototype pin at one end of the second mother pipe; fastening the box and the prototype pin together and measuring the circumferential deviation α between the first marking and the second marking in the fastened state; and placing a third mother pipe having a third marking on its outer circumferential surface on the first lathe so that the third marking is in the initial position for pin machining, and forming the pin at one end of the third mother pipe using a program in which the rotation angle of the mother pipe is offset by the deviation α from the program used to machine the prototype pin.

[0015] According to this configuration, after forming a box and a prototype pin on each of the first and second blank tubes, they are fastened together, and the circumferential deviation α between the first marking on the first blank tube and the second marking on the second blank tube is measured. Then, the third blank tube is placed on the same lathe as the lathe used to machine the prototype pin. The third blank tube is placed in the same lathe as the lathe used to machine the prototype pin, so that the third marking on the third blank tube is at the same initial machining position (pin machining initial position) as the initial machining position of the second marking in the process of forming the prototype pin. The pin is then formed on the third blank tube using a program in which the rotation angle of the blank tube is offset by the deviation α from the program used in the process of forming the prototype pin. This allows the circumferential deviation between the first marking and the third marking to be reduced when the box and pin are fastened together.

[0016] In the above embodiment, the step of forming the prototype pin may include a step of matching the position of the marking on the chuck of the first lathe with the position of the second marking, and the step of forming the pin may include a step of matching the position of the marking on the chuck with the position of the third marking.

[0017] In the above embodiment, the step of forming the box may include the steps of placing the first blank tube on a lathe so that the first marking is at a predetermined initial position for box processing, and forming the box at one end of the first blank tube. This configuration makes it possible to maintain a consistent relationship between the first marking and the shape of the box each time a plurality of tubes are manufactured.

[0018] The manufacturing method according to the above embodiment may further include the steps of rotating the first mother tube on which the box has been formed 180° around a rotation axis perpendicular to the tube axial direction, placing the first mother tube on the lathe used for machining the box so that the first marking is at the initial position for machining the box, and forming a second box on the end of the first mother tube opposite the end on which the box was formed. This configuration allows the box and the second box to have symmetrical shapes.

[0019] The manufacturing method according to the above embodiment may further include the steps of rotating the third blank tube with the pin formed thereon 180° around a rotation axis perpendicular to the tube axial direction, placing the third blank tube on a first lathe so that the third marking is at the pin machining initial position, and forming a second pin on the end of the third blank tube opposite the end where the pin was formed, using the program used for machining the pin. This configuration allows the pin and the second pin to have symmetrical shapes.

[0020] In the above embodiment, one end and the other end of the third raw pipe may be machined using different lathes.

[0021] The manufacturing method according to the above embodiment may further include the steps of: placing the second blank tube on a second lathe different from the first lathe so that the second marking is at a predetermined second pin machining initial position, and forming a second prototype pin on the end of the second blank tube opposite to the end where the prototype pin was formed; fastening the box and the second prototype pin and measuring the circumferential deviation β between the first marking and the second marking in the fastened state; and placing the third blank tube on the second lathe so that the third marking is at the second pin machining initial position, and forming the second pin on the end of the third blank tube opposite to the end where the pin was formed, using a program in which the rotation angle of the blank tube is offset by the deviation β from the program used to machine the second prototype pin.

[0022] The manufacturing method according to the above embodiment may further include the steps of: obtaining a marking gauge from a third blank tube so as to include the third marking and the pin; placing the fourth blank tube, which has a fourth marking on its outer peripheral surface, on a lathe so that the fourth marking is at a predetermined initial position for machining a prototype box, and forming a prototype box on the fourth blank tube; fastening the marking gauge and the prototype box together, and measuring the circumferential deviation γ between the third marking and the fourth marking in the fastened state; and placing a fifth blank tube, which has a fifth marking on its outer peripheral surface, on the lathe used to machine the prototype box so that the fifth marking is at the initial position for machining the prototype box, and forming the box at one end of the fifth blank tube using a program in which the rotation angle of the blank tube is offset by the deviation γ from the program used to machine the prototype box.

[0023] In the above embodiment, the pin may have a pin shoulder surface, and the box may have a box shoulder surface that contacts the pin shoulder surface in the fastened state.

[0024] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated. The dimensional ratios between the components shown in each drawing do not necessarily represent the actual dimensional ratios.

[0025] [Pipe threaded joints] Fig. 1 is a plan view showing a schematic configuration of a tubular threaded joint 10, which is an example of a tubular threaded joint. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in Fig. 2, the tubular threaded joint 10 comprises a tubular pin 20 provided at the tip of a pipe 40, and a tubular box 30 into which the pin 20 is screwed and fastened to the pin 20. The pin 20 has a male thread 21 formed on its outer periphery. The box 30 has a female thread 31 formed on its inner periphery and which mates with the male thread 21 when fastened.

[0026] In the tubular threaded joint 10, the pins 20 are formed on both ends of the pipe 40, and the boxes 30 are formed on both ends of the pipe 50. In other words, the tubular threaded joint 10 is a coupling-type threaded joint.

[0027] Each of the tubes 40 and 50 is typically a steel tube, but may also be a metal tube made of a nickel-based alloy or the like.

[0028] A reference line RL (Figure 1), which is a line indicating a reference position in the circumferential direction, is provided on the outer peripheral surface of at least one of the pipes 40 and 50. The tubular threaded joint 10 is configured so that the reference lines RL are aligned in a straight line when multiple pipes 40 and 50 are joined together. In other words, the tubular threaded joint 10 is configured so that, when the pin 20 and box 30 are fastened together, the reference lines RL of the joined pipes are aligned in the same straight line.

[0029] Here, the "fastened state" refers to a state in which make-up is complete, and can be, for example, a state in which the pin shoulder surface 22 and the box shoulder surface 32 are in contact. Alternatively, in the case of a tubular threaded joint in which the make-up torque changes depending on the degree of make-up between the pin 20 and the box 30 (for example, a tubular threaded joint with wedge threads), the state in which the make-up torque has reached a predetermined magnitude can be considered to be the "fastened state." When the make-up state is controlled by the make-up torque, the tubular threaded joint 10 does not have to have a pin shoulder surface 22 and a box shoulder surface 32.

[0030] [Manufacturing method for pipe threaded joints] [First embodiment] The method for manufacturing a tubular threaded joint according to this embodiment is a method for manufacturing a tubular threaded joint using a lathe capable of program control by a computer (so-called NC lathe). More specifically, the method for manufacturing a tubular threaded joint according to this embodiment is a method for manufacturing a tubular threaded joint by forming a pin or box by processing a pipe (hereinafter referred to as a "blank pipe") that has undergone processing prior to the formation of the pin or box using a lathe.

[0031] 3 is a flow diagram showing a method for manufacturing a tubular threaded joint according to a first embodiment of the present invention. This manufacturing method comprises the steps of: forming a box at one end of a mother pipe BP1 (first mother pipe) (step S1); forming a box (second box) at the other end of the mother pipe BP1 (step S2); forming a prototype pin on a mother pipe BP2 (second mother pipe) (step S3); fastening the box and the prototype pin together and measuring the amount of misalignment α (step S4); forming a pin at one end of a mother pipe BP3 (third mother pipe) (step S5); and forming a pin (second pin) at the other end of the mother pipe BP3 (step S6). Each step is described in detail below.

[0032] First, a blank pipe BP1 (first blank pipe) is processed (steps S1 and S2). Figures 4 to 7 are schematic diagrams for explaining these steps.

[0033] As shown in Figure 4, a marking M1 (first marking) is provided on the outer circumferential surface of the mother pipe BP1. The marking M1 is preferably provided as a straight line parallel to the axial direction of the mother pipe BP1. The marking M1 does not need to be provided over the entire length of the mother pipe BP1; for example, it may be provided only near one end (one end or both ends) of the mother pipe BP1. The marking M1 may be formed by processing a portion of the outer circumferential surface of the mother pipe BP1 (e.g., a groove), but is more preferably drawn with a pen or the like. If the marking M1 is drawn with a pen or the like, it does not affect the performance of the tubular threaded joint and is easy to apply.

[0034] A lathe L0 capable of computer program control is used to machine the blank pipe BP1. The lathe L0 is equipped with a chuck C0 for fixing the blank pipe BP1 and a tool T0. The lathe L0 is equipped with a mechanism for rotating the blank pipe BP1 around the tube axis and a mechanism for moving the tool T0. The lathe L0 machines the blank pipe BP1 according to a preset program.

[0035] First, as shown in FIG. 5, a box B1 is formed at one end of a blank pipe BP1 (step S1).

[0036] At this time, it is preferable to machine the blank pipe BP1 by placing it on the lathe L0 so that the marking M1 is at a predetermined initial machining position (initial box machining position). This can be achieved, for example, by marking the blank pipe BP1 at a predetermined position on the chuck C0 of the lathe L0, fixing the blank pipe BP1 to the chuck C0 so that the marking M1 and the marking CM0 are aligned, and then machining the blank pipe BP1, as shown in Figure 4. This allows the relationship between the marking M1 and the shape of the box B1 to be consistent each time a plurality of tubes are manufactured.

[0037] In this embodiment, as will be described later, an adjustment is made to minimize the circumferential misalignment that occurs between the joined pipes when the pin and box are fastened together. Hereinafter, this adjustment will be referred to as "phase alignment." When manufacturing multiple pipes, if the relationship between the marking M1 and the shape of the box B1 is consistent each time, phase alignment only needs to be performed once, and subsequent phase alignments can be omitted.

[0038] Next, as shown in Figure 6, the base tube BP1 on which the box B1 has been formed is rotated 180 degrees around a rotation axis perpendicular to the tube axis direction and fixed to a chuck C0, and as shown in Figure 7, a box B2 (second box) is formed at the other end of the base tube BP1 (step S2).

[0039] At this time, it is preferable to place the blank tube BP1 on the lathe L0 and machine the blank tube BP1 so that the marking M1 is at the same initial machining position (box machining initial position) as the initial machining position in the process of forming the box B1 (step S1). This can be achieved, for example, by fixing the blank tube BP1 to the chuck C0 and machining the blank tube BP1 so that the marking M1 and the marking CM0 are aligned, as shown in Fig. 6.

[0040] By setting the same initial processing position in the process of forming box B1 (step S1) and the process of forming box B2 (step S2), it is possible to make box B1 and box B2 symmetrical in shape. If box B1 and box B2 have symmetrical shapes, it is sufficient to perform phase alignment for one of box B1 and box B2, and phase alignment for the other box can be omitted.

[0041] Next, a prototype pin is formed on the blank pipe BP2 (second blank pipe) (step S2). Figures 8 and 9 are schematic diagrams for explaining this step.

[0042] 8, like the mother pipe BP1, the mother pipe BP2 also has a marking M2 (second marking) on ​​its outer circumferential surface. The marking M2 is preferably a straight line parallel to the axial direction of the mother pipe BP2. The marking M2 does not need to be provided over the entire length of the mother pipe BP2, and may be provided, for example, only near one end (or both ends) of the mother pipe BP2.

[0043] As with the machining of the mother pipe BP1, the mother pipe BP2 is machined using a lathe L1 (first lathe) that can be program-controlled by a computer. Like the lathe L0, the lathe L1 is equipped with a chuck C1 and a tool T1. The lathe L1 may be the same lathe as the lathe L0 used to machine the mother pipe BP1, or it may be a different lathe.

[0044] As shown in FIG. 9, a prototype pin TP1 is formed at one end of the blank tube BP2 (step S3).

[0045] At this time, the blank pipe BP2 is placed on the lathe L1 so that the marking M2 is at a predetermined initial position for machining (initial position for pin machining), and then the blank pipe BP2 is machined. This can be achieved, for example, by providing a marking CM1 at a predetermined position on the chuck C1 of the lathe L1, fixing the blank pipe BP2 to the chuck C1 so that the marking M2 and the marking CM1 are aligned, as shown in Figure 8, and then machining the blank pipe BP2.

[0046] Next, the box B1 and the prototype pin TP1 are fastened together, and the amount of deviation α in the circumferential direction between the marking M1 and the marking M2 in the fastened state is measured (step S4). Fig. 10 is a schematic diagram for explaining this step.

[0047] As described above, the "fastened state" refers to a state in which the fastening is completed. The deviation amount α can be, for example, a value obtained by dividing the distance along the circumferential direction of the mother pipe BP1 by the radius of the mother pipe BP1, or a value obtained by dividing the distance along the circumferential direction of the mother pipe BP2 by the radius of the mother pipe BP2 (an angle expressed in radians).

[0048] Next, a blank pipe BP3 (third blank pipe) is processed (steps S5 and S6). Figures 11 to 14 are schematic diagrams for explaining these steps.

[0049] 11, like the mother pipe BP2, the mother pipe BP3 also has a marking M3 (third marking) on ​​its outer circumferential surface. The marking M3 is preferably a straight line parallel to the axial direction of the mother pipe BP3. The marking M3 does not need to be provided over the entire length of the mother pipe BP3, and may be provided, for example, only near one end (or both ends) of the mother pipe BP3.

[0050] The blank pipe BP3 is machined using the lathe L1 (first lathe) used to machine the blank pipe BP2.

[0051] First, as shown in FIG. 12, a pin P1 is formed at one end of a blank pipe BP3 (step S5).

[0052] At this time, the blank tube BP3 is placed on the lathe L1 and machined so that the marking M3 is at the same initial machining position (pin machining initial position) as the initial machining position in the step of forming the prototype pin (step S3). This can be achieved, for example, by fixing the blank tube BP3 to a chuck C1 and machining the blank tube BP3 so that the marking M3 and the marking CM1 are aligned, as shown in Figure 11.

[0053] In the process of forming the pin P1 (step S5), the blank tube BP3 is machined using a program that offsets the rotation angle of the blank tube (the rotation angle around the tube axis; the same applies below) by a deviation amount α from the program used in the process of forming the prototype pin (step S3). In other words, the blank tube BP3 is machined using a program that offsets the rotation angle of the blank tube in a direction that cancels the deviation amount α from the program used in the process of forming the prototype pin (step S3). This reduces the circumferential deviation between the marking M1 (Figure 7) and the marking M3 when the box B1 and the pin P1 are fastened together.

[0054] Next, as shown in Figure 13, the base tube BP3 on which the pin P1 has been formed is rotated 180 degrees around a rotation axis perpendicular to the tube axis direction and fixed to a chuck C1, and as shown in Figure 14, a pin P2 (second pin) is formed at the other end of the base tube BP3 (step S6).

[0055] In this case, too, it is preferable to machine the blank tube BP3 by placing it on the lathe L1 so that the marking M3 is at the same initial machining position (pin machining initial position) as the initial machining position in the step of forming the prototype pin (step S3). Also, in the step of forming the pin P2 (step S6), it is preferable to machine the blank tube BP3 using a program in which the rotation angle of the blank tube is offset by the deviation amount α from the program used in the step of forming the prototype pin (step S3) (i.e., the program used in the step of forming the pin P1 (step S5)). This allows the pins P1 and P2 to have symmetrical shapes.

[0056] A tubular threaded joint is manufactured through the above steps. In the method of manufacturing a tubular threaded joint according to this embodiment, a mother pipe BP1 (Fig. 7) with boxes (boxes B1 and B2) formed at both ends corresponds to the pipe 50 in Fig. 1, and a mother pipe BP3 (Fig. 14) with pins (pins P1 and P2) formed at both ends corresponds to the pipe 40 in Fig. 1. The marking M1 on the mother pipe BP1 and the marking M3 on the mother pipe BP3 may be left as they are and used as the reference line RL in Fig. 1.

[0057] In the manufacturing method of a cylindrical component described in Japanese Patent No. 4741497, the shape of the pin or box is modified using an axial offset C expressed by the following formula: C=P×(α+Q) / 2π where P is the thread pitch, α is the deviation in radians, and Q is a predefined set point.

[0058] The manufacturing method disclosed in Japanese Patent No. 4741497 has the following problems. The formula for the axial offset C is a theoretical formula and does not take into account variations in the thread pitch P. For example, even if the design value is P = 5.08 mm, the actual value may be P = 5.07 mm. Variations in P may make it impossible to accurately adjust the circumferential misalignment between the joined pipes.

[0059] Furthermore, Japanese Patent No. 4741497 states that "the set value Q can be experimentally defined as a function of various parameters such as assembly torque and amount of grease." In other words, testing is required to determine the value of Q before manufacturing.

[0060] Furthermore, when a tubular threaded joint has a tapered thread, the following problem occurs. Figure 15 is a cross-sectional view showing a schematic view of the shape of pin 90A before the axial offset C is applied, and the shape of pin 90B after the axial offset C is applied. 91A and 91B are the threaded portions of pin 90A and pin 90B, respectively. By applying the axial offset C, the distance from the tip of the shoulder to the thread changes by L1 - L2 = C.

[0061] Figure 16 is a diagram in which the cross-sectional outline of pin 90A and the cross-sectional outline of pin 90B are superimposed. As can be seen from Figure 16, by applying the axial offset C, the thread diameter of pin 90B becomes larger than the thread diameter of pin 90A. Therefore, when the axial offset C is applied, the radial dimension also needs to be corrected.

[0062] Furthermore, the manufacturing method disclosed in Japanese Patent No. 4741497 can only be applied to tubular threaded joints in which the fastened state is when the shoulder surfaces are in contact with each other.

[0063] The manufacturing method for a tubular threaded joint according to this embodiment can solve all of the above problems. With the manufacturing method according to this embodiment, there is no need to consider variations in thread pitch P. Furthermore, no testing is required to define the set value Q. Furthermore, even if the tubular threaded joint has a tapered thread, there is no need to modify the radial dimensions. Furthermore, the manufacturing method according to this embodiment can also be applied to tubular threaded joints in which the make-up state is controlled by make-up torque.

[0064] The above has described a method of manufacturing a tubular threaded joint according to the first embodiment of the present invention. According to this embodiment, circumferential misalignment between joined pipes can be adjusted with greater precision than conventional methods.

[0065] In the above embodiment, the case of manufacturing a coupling-type tubular threaded joint has been described, but the method of manufacturing a tubular threaded joint according to this embodiment can also be applied to the manufacture of an integral-type tubular threaded joint. In an integral-type threaded joint, a pin is formed at one end of the pipe and a box is formed at the other end. For example, after manufacturing an integral-type tubular threaded joint, the box portion can be cut and the cut box can be fastened to the pin to measure the amount of deviation α. ​​Alternatively, marking gauges for the pin and the box can be prepared to measure the amount of deviation α.

[0066] [Second embodiment] Figure 17 is a flow diagram showing a method for manufacturing a tubular threaded joint according to a second embodiment of the present invention. In addition to the steps of the manufacturing method according to the first embodiment (Figure 3), this manufacturing method further comprises the step of forming a second trial pin on a mother pipe BP2 (step S7), and the step of fastening the box and the second trial pin to measure the amount of deviation β (step S8). Furthermore, the step of forming a pin on the other end of the mother pipe BP3 (step S9) differs from the same step in the first embodiment (step S6 in Figure 3).

[0067] The steps of processing the blank pipe BP1 (first blank pipe) (steps S1 and S2) and the step of forming a prototype pin at one end of the blank pipe BP2 (second blank pipe) (step S3) are the same as those in the first embodiment.

[0068] In this embodiment, a second trial pin is further formed at the other end of the blank pipe BP2 (step S7). Figures 18 and 19 are schematic diagrams for explaining this step.

[0069] For this processing, a lathe L2 (second lathe) different from the lathe L1 (first lathe, see Figure 9) used to form the prototype pin TP1 is used. Like the lathe L1, the lathe L2 is also a lathe that can be program-controlled by a computer, and is equipped with a chuck C2 and a tool T2.

[0070] As shown in FIG. 19, a second trial pin TP2 is formed at the other end of the blank tube BP2 (step S7).

[0071] At this time, the blank tube BP2 is placed on the lathe L2 so that the marking M2 is at a predetermined initial machining position (second pin machining initial position), and then the blank tube BP2 is machined. This can be achieved, for example, by providing a marking CM2 at a predetermined position on the chuck C2 of the lathe L2, fixing the blank tube BP3 to the chuck C2 so that the marking M2 and the marking CM2 are aligned, and then machining the blank tube BP2, as shown in Figure 18.

[0072] The process (step S4) of fastening the box B1 and the prototype pin TP1 and measuring the amount of deviation α is the same as in the first embodiment.

[0073] In this embodiment, the box B1 and the second trial pin TP2 are further fastened together, and the circumferential deviation β between the markings M1 and M2 in the fastened state is measured (step S8). Fig. 20 is a schematic diagram for explaining this step. The step of measuring the deviation β (step S8) can be performed in the same manner as the step of measuring the deviation α (step S4).

[0074] Next, a blank pipe BP3 (third blank pipe) is processed (steps S5 and S9). Among these, the step of forming a pin at one end of the blank pipe BP3 (step S5) is the same as in the first embodiment.

[0075] 21 and 22 are schematic diagrams illustrating the step of forming a pin at the other end of the mother tube BP3 (step S9). In this embodiment, unlike the first embodiment, the lathe L2 used in the step of forming the second prototype pin TP2 (step S7) is used to form the pin P2 at the other end of the mother tube BP3 (step S9).

[0076] At this time, the blank tube BP3 is placed on the lathe L2 and machined so that the marking M3 is at the same initial machining position (second pin machining initial position) as the initial machining position in the step of forming the second trial pin (step S7). This can be achieved, for example, by fixing the blank tube BP3 to the chuck C2 and machining the blank tube BP3 so that the marking M3 and the marking CM2 are aligned, as shown in Fig. 21.

[0077] In the process of forming the pin P2 (step S9), the blank tube BP3 is machined using a program that offsets the rotation angle of the blank tube by a deviation amount β from the program used in the process of forming the second prototype pin (step S7). This reduces the circumferential deviation between the marking M1 (Figure 7) and the marking M3 when the box B1 and the pin P2 are fastened together.

[0078] A threaded joint for pipes is manufactured through the above steps.

[0079] In the manufacturing method according to the first embodiment, as shown in FIGS. 11 to 14, both ends of the mother pipe BP3 are machined on a single lathe (lathe L1). Accordingly, in the manufacturing method according to the first embodiment, the mother pipe BP3 is rotated 180°. A large space is required to rotate the long mother pipe BP3. Furthermore, if a crane is used to rotate the mother pipe BP3, a person is required to operate the crane, making automation difficult.

[0080] In contrast, in the manufacturing method according to the second embodiment, one end and the other end of the mother pipe BP3 are machined using different lathes (lathe L1 and lathe L2). Accordingly, in the manufacturing method according to the second embodiment, the offset amounts (offset amounts α and β) are adjusted for each of the two lathes. Meanwhile, in the manufacturing method according to the second embodiment, it is not necessary to rotate the mother pipe BP3 by 180°. This allows for a compact equipment layout. Automation is also relatively easy.

[0081] The above has described a method of manufacturing a tubular threaded joint according to the second embodiment of the present invention. This embodiment also makes it possible to adjust circumferential misalignment between joined pipes with greater precision than conventional methods.

[0082] In the above embodiment, the second trial pin TP2 is formed at one end of the mother tube BP2, the other end of which has the trial pin TP1 formed thereon, and the deviation amount β is measured using this. However, instead of this, the second trial pin TP2 may be formed on a mother tube other than the mother tube BP2, and the deviation amount β may be measured using this.

[0083] In the above embodiment, the marking M2 is used as a reference for measuring both the amount of deviation α and the amount of deviation β. However, the marking used for measuring the amount of deviation β does not have to be the same as the marking used for measuring the amount of deviation β. For example, a marking M2a different from the marking M2 may be applied to the mother tube BP2, and the mother tube BP2 may be placed on the lathe L2 so that the marking M2a is at a predetermined processing initial position (the second pin processing initial position), to form the second trial pin TP2. In this case, the amount of circumferential deviation between the marking M1 and the marking M2a when the box B1 and the second trial pin TP2 are fastened together is β.

[0084] [Third embodiment] Figure 23 is a flow diagram showing a method for manufacturing a tubular threaded joint according to a third embodiment of the present invention. In addition to the steps of the manufacturing method according to the first embodiment (Figure 3), this manufacturing method further comprises the steps of taking a marking gauge from a mother pipe BP3 (step S10), forming a trial box on a mother pipe BP4 (fourth mother pipe) (step S11), fastening the marking gauge and the trial box together to measure the amount of deviation γ (step S12), and forming a box on a mother pipe BP5 (fifth mother pipe) (step S13). Figures 24 to 27 are schematic diagrams for explaining these steps.

[0085] The method for manufacturing a tubular threaded joint according to this embodiment is a method for manufacturing a box when, for example, it becomes necessary to manufacture a box that can be connected in-line with a pin that has been manufactured in the past, using a marking gauge (also called a "strip" or "bullet") that has been taken from the pin in advance and stored.

[0086] First, as shown in Fig. 24, a marking gauge G is taken from a blank pipe BP3 (third blank pipe) so as to include a marking M3 (third marking) and a pin P1 (step S10). The shape of the marking gauge G in Fig. 24 is an example, and the shape of the marking gauge G is not limited to this. The marking gauge G may have any shape including the marking M3 and the pin P1.

[0087] Next, as shown in Fig. 25, a prototype box TB1 is formed on a blank pipe BP4 (fourth blank pipe) having a marking M4 (fourth marking) on ​​its outer circumferential surface (step S11). In the following, a case will be described in which the blank pipe BP4 is machined using a lathe L0 as shown in Fig. 25, but any lathe can be used to machine the blank pipe BP4. The lathe used to machine the blank pipe BP4 may be lathe L1 (Fig. 11) or lathe L2 (Fig. 18), or may be another lathe.

[0088] At this time, the blank tube BP4 is placed on the lathe L0 so that the marking M4 is at a predetermined initial machining position (initial machining position for the prototype box), and then the blank tube BP4 is machined. This can be achieved, for example, by fixing the blank tube BP4 to the chuck C0 so that the marking M4 and the marking CM0 are aligned, as shown in Figure 25, and then machining the blank tube BP4.

[0089] Next, as shown in FIG. 26, the marking gauge G and the prototype box TB1 are fastened together, and the amount of circumferential deviation γ between the marking M3 and the marking M4 in the fastened state is measured (step S12).

[0090] Next, as shown in Fig. 27, a box B1 is formed on a blank tube BP5 (fifth blank tube) having a marking M5 (fifth marking) on ​​its outer circumferential surface (step S13). The box B1 is machined using the same lathe (lathe L0) as that used in the step of forming the prototype box (step S11).

[0091] At this time, the blank tube BP5 is placed on the lathe L0 and machined so that the marking M5 is at the same initial machining position (initial machining position for the prototype box) as the initial machining position in the step of forming the prototype box (step S11). This can be achieved, for example, by fixing the blank tube BP5 to the chuck C0 and machining the blank tube BP5 so that the marking M5 and the marking CM0 are aligned, as shown in Figure 27.

[0092] In the box forming process (step S13), the blank tube BP5 is machined using a program that offsets the rotation angle of the blank tube by the deviation amount γ from the program used in the prototype box forming process (step S11). This reduces the circumferential deviation between the markings M3 and M5 when the box B1 and the pin P1 are fastened together.

[0093] The above has described a method of manufacturing a tubular threaded joint according to the third embodiment of the present invention. According to this embodiment, it is possible to manufacture a box that allows for in-line connection with a pin that has been manufactured previously.

[0094] Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be appropriately modified and carried out without departing from the spirit of the present invention. [Explanation of symbols]

[0095] 10 Pipe threaded joints 20-pin 21 Male thread 22 Pin shoulder surface 30 boxes 31 Female thread 32 Box shoulder surface 40, 50 tubes BP1 mother tube (first mother tube) BP2 mother tube (second mother tube) BP3 mother tube (third mother tube) BP4 mother tube (fourth mother tube) BP5 mother tube (5th mother tube) M1 marking (first marking) M2 marking (second marking) M3 marking (third marking) M4 marking (4th marking) M5 marking (5th marking) B1 Box B2 Box (2nd Box) TP1 Prototype Pin TP2 2nd prototype pin P1 pin P2 pin (second pin) TB1 Prototype Box L0 lathe L1 Lathe (First Lathe) L2 lathe (second lathe)

Claims

1. A method for manufacturing a tubular threaded joint, in which a tubular threaded joint is manufactured using one or more lathes that can be program-controlled by a computer, The tubular threaded joint comprises a tubular pin provided at the tip of a pipe, and a tubular box into which the pin is screwed and fastened, the pin having a male thread formed on its outer periphery, and the box having a female thread formed on its inner periphery that mates with the male thread when fastened, forming the box at one end of a first mother tube having a first marking on an outer circumferential surface; a step of placing a second blank tube having a second marking on its outer peripheral surface in a first lathe so that the second marking is positioned at a predetermined initial position for pin machining, and forming a prototype pin at one end of the second blank tube; a step of fastening the box and the prototype pin together and measuring a circumferential deviation amount α between the first marking and the second marking in the fastened state; placing a third mother pipe, which has a third marking provided on its outer peripheral surface, in the first lathe so that the third marking is at the pin machining initial position, and forming the pin at one end of the third mother pipe using a program in which the rotation angle of the mother pipe is offset by the deviation amount α from the program used to machine the prototype pin.

2. A method for manufacturing a tubular threaded joint according to claim 1, the step of forming the trial pin includes a step of matching a position of a marking provided on a chuck of the first lathe with a position of the second marking; A method for manufacturing a tubular threaded joint, wherein the step of forming the pin includes a step of aligning the position of a marking provided on the chuck with the position of the third marking.

3. A method for manufacturing a tubular threaded joint according to claim 1 or 2, The step of forming the box includes: placing the first mother pipe on a lathe so that the first marking is at a predetermined initial position for box machining, and forming the box at the one end of the first mother pipe.

4. A method for manufacturing a tubular threaded joint according to claim 3, further comprising: a first mother pipe having a box formed therein, rotating the first mother pipe by 180° around a rotation axis that is perpendicular to the pipe axial direction, and then placing the first mother pipe on the lathe that was used to machine the box so that the first marking is in the initial position for box machining, and forming a second box at an end of the first mother pipe opposite to the end where the box was formed.

5. A method for manufacturing a tubular threaded joint according to any one of claims 1 to 4, further comprising: a third blank pipe having the pin formed therein, rotating the third blank pipe by 180° around a rotation axis that is perpendicular to the pipe axial direction, and then placing the third blank pipe on the first lathe so that the third marking is in the pin machining initial position; and using a program that was used to machine the pin, forming a second pin at an end of the third blank pipe opposite to the end at which the pin was formed.

6. A method for manufacturing a tubular threaded joint according to any one of claims 1 to 4, a method for manufacturing a tubular threaded joint, wherein one end and the other end of the third mother pipe are machined on different lathes.

7. A method for manufacturing a tubular threaded joint according to claim 6, further comprising: placing the second blank tube on a second lathe different from the first lathe so that the second marking is at a predetermined second pin machining initial position, and forming a second prototype pin on an end of the second blank tube opposite to the end on which the prototype pin is formed; a step of fastening the box and the second trial pin together, and measuring a circumferential deviation amount β between the first marking and the second marking in a fastened state; and placing the third blank pipe on the second lathe so that the third marking is at the initial position of machining the second pin, and forming a second pin at an end of the third blank pipe opposite to the end at which the pin was formed, using a program in which the rotation angle of the blank pipe is offset by the deviation amount β from the program used to machine the second trial pin.

8. A method for manufacturing a tubular threaded joint according to any one of claims 1 to 7, the pin has a pin shoulder surface, and the box has a box shoulder surface that contacts the pin shoulder surface in a fastened state; The method for manufacturing a tubular threaded joint further comprises: extracting a marking gauge from the third mother tube so as to include the third marking and the pin; a step of placing a fourth blank tube having a fourth marking on its outer peripheral surface on a lathe so that the fourth marking is positioned at a predetermined initial position for machining a prototype box, and forming a prototype box from the fourth blank tube; a step of placing the marking gauge and the prototype box in a state where the male thread of the pin and the female thread of the prototype box are fitted together and the pin shoulder surface is in contact with the box shoulder surface, and measuring a circumferential deviation amount γ between the third marking and the fourth marking in this state; and placing a fifth mother pipe, which has a fifth marking provided on its outer peripheral surface, on the lathe that was used to machine the prototype box so that the fifth marking is in an initial position for machining the prototype box, and forming the box at one end of the fifth mother pipe using a program in which the rotation angle of the mother pipe is offset by the deviation amount γ from the program that was used to machine the prototype box.

9. A method for manufacturing a tubular threaded joint according to any one of claims 1 to 7, a pin having a pin shoulder surface, and a box having a box shoulder surface that contacts the pin shoulder surface in a fastened state.

Images