JP3685242B2 - Cutting method of tapered square screw - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for cutting a tapered square screw into a steel pipe such as an oil well pipe having a special seal portion at a pipe end.
[0002]
[Prior art]
For example, API-standard buttress screws have been developed since oil well pipe screws used for drilling oil and natural gas have extremely strict requirements in terms of manufacturing and applications. However, oil wells in recent years have become extremely deep, and there is a demand for improved joint strength and airtightness over API standard buttress screws. For this reason, special extreme line square screws for oil and natural gas wells that require greater strength and leakage prevention have been developed and standardized.
[0003]
For example, in the case of a male screw, this extreme line square screw is a screw joint of a play side flank 53 and a pressure side flank 54 of a thread 52 at the end of a steel pipe 51, as shown in FIGS. 6 (a) and 6 (b). The opposite tube end-side angles α ₁ and α ₂ with respect to the shaft have a tapered rectangular screw shape. In such an extreme line rectangular threaded joint thread cutting, after machining the under-taper outer diameter part, as shown in Fig. 7 (a), several thread shapes formed into a finished thread shape Using a chaser 71 having cutting edges X and Y, as shown in FIG. 7 (b), for example, as shown in FIG.
[0004]
As another thread cutting method or thread cutting tool, a predetermined step is provided at a predetermined interval between a total cutting tool in which a side blade portion and a lower blade portion are provided on a tool holder and a thread cutting tool. A steel pipe threading method having a special seal part at the pipe end using a cutting tool provided and integrally assembled, wherein the end face and the outer surface of the seal part are used by using the side blade part of the total shape bite A step of cutting a taper outer diameter portion using a lower blade portion of the total shape bite, and a screw cutting work on the taper outer diameter portion using a screw cutting tool. Threading method for steel pipe (Japanese Patent Publication No. 6-102285), which is a continuous process in a series of operations Tool body and chuck of the tool body Triangular or quadrilateral inserts attached to form corner angles in the direction crossing the spindle axis direction at the side end face corners, and a chaser provided on the inner side in the spindle axis direction from the tip mounting position of the tool body A combination tool (Japanese Utility Model Publication No. 62-53921) that performs chamfering of the end face, inner and outer faces of steel pipes, outer diameter machining and threading with a chaser is proposed from the tip apex angle and slope load Has been.
[0005]
[Problems to be solved by the invention]
The conventional threading of steel pipes using the chaser uses one chaser, for example, to perform thread cutting by three-pass thread cutting. If a missing chaser occurs, the product becomes defective. In addition, this method has a problem that the threader-shaped cutting edge of the chaser is worn quickly and the life of the chaser is short because a single chaser is used to cut several passes.
[0006]
In addition, in order to improve the thread cutting efficiency, it is necessary to reduce the number of thread cutting passes. However, if only one chaser is used as in the conventional case, the number of chaser per pass is reduced. As a result, the cutting load of the chaser was significantly reduced.
[0007]
Even when two chases are used for roughing and finishing, the cross-section square screw with a sharp angle opposite to the end of the threaded joint of the cutting edge follower flank and lead flank on the roughing chaser When the shape of the thread-shaped cutting edge is adopted, as shown in FIG. 8, when grinding the chaser 81, the side surfaces of the thread-shaped cutting edges X and Y are acute with respect to the axis of the threaded joint. Since it is necessary, as shown in FIG. 9, it is necessary to perform grinding with a grinder 82 for each of the chases 81. For this reason, the chaser grinding requires a lot of man-hours, and the chaser 81 is expensive.
[0008]
The object of the present invention is to eliminate the above-mentioned problems of the prior art, and to prevent the occurrence of defective products even when a chip in the rough machining chaser is broken during the machining, so that the machining cost of the rough machining chaser can be increased. Another object of the present invention is to provide a roughing chaser capable of simultaneously grinding a plurality of pieces and a thread cutting method using a finishing chaser.
[0009]
[Means for Solving the Problems]
In the taper-shaped square screw cutting method of the present invention, after processing the taper outer diameter portion under the screw, the anti-pipe end side angles α ₁ and α _{2 with} respect to the thread joint axis of the thread side idle side flank and the pressure side flank. When cutting a screw with an acute tapered square screw shape, the angle β ₂ opposite to the pipe end of the follower flank of the cutting edge is an obtuse angle or a right angle, and the axis of the lead flank threaded joint anti tube end angle beta ₁ is used Cheza for rough machining with a cutting edge of an acute buttress thread shape 3 mountain above, to provide one or more crude threading for. Then, the anti-tube end-side angle gamma ₁ with respect to the axis of the threaded joint of the stabbing flank cutting edge are identical and counter tube end angle alpha ₁ relative to the axis of the threaded joint of the clearance flank of the thread of the tapered square screw, and follow flank anti pipe end side angles gamma ₂ with respect to the axis of the threaded joint, the anti-tube end angle alpha ₂ of the same screws with respect to the axis of the threaded joint of the pressure side flank of the thread of the tapered square screw A finishing chaser having one or more angle cutting edges is used to perform one or more finishing threads.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Cutting method of tapered square screw of the present invention, after processing the untapped tapered outer diameter, counter-tube end angle beta ₂ with respect to the axis of the threaded joint follow flank cutting edge an obtuse angle or a right angle, the flow proceeds and Cheza for rough machining counter tube end angle beta ₁ with respect to the axis of the side flanks threaded joint has a cutting edge of an acute buttress thread shape 3 mountain above, anti-tube with respect to the axis of the threaded joint of the stabbing flank cutting edge The end-side angle γ ₁ is the same as the anti-pipe end-side angle α ₁ with respect to the threaded joint flank of the thread of the tapered square screw thread , and the anti-pipe end-side angle with respect to the shaft of the follower flank threaded joint degrees gamma ₂ is two Cheza for finishing operation with a counter-pipe end side angle alpha ₂ of the same thread profile cutting edge relative to the axis of the pressure flank of the threaded joint of the threads of the tapered square screw or one peak For use, rough machining Even if defects occur over The can cutting in Cheza for finishing, it is possible to prevent the occurrence of defective products.
[0011]
Further, the cutting method of the tapered square screw according to the present invention can reduce the number of times of finishing chaser required for machining by cutting most of the screw with a roughing chaser, and the life of the chaser Can be extended.
[0012]
Furthermore, the rough machining chaser has a large width in the axial direction of the threaded joint to be machined and has three or more cutting edges. The number of grinding passes required can be reduced, and the thread cutting efficiency can be improved.
[0013]
Furthermore, the chaser for rough machining employs a saw-tooth thread-shaped cutting blade with an obtuse or right-angled anti-pipe end side angle β ₂ with respect to the threaded joint axis of the trailing edge of the cutting edge. When the chaser is ground, several chases for roughing can be ground at the same time, so the number of chaser grinding steps can be reduced, and as a result, the chaser for roughing can be obtained at a low price.
[0014]
【Example】
As shown in FIG. 1 (a), in the anti-tube end-side angle beta ₁ with respect to the axis of the cutting edge of the stabbing flank 1 of the threaded joint is acute, anti pipe end side angle relative to the axis of the chase flank 2 of the threaded joint beta A roughing chaser 3 having four threads A to D in the form of a sawtooth screw ₂ having a right angle, and a threaded joint of the leading flank 11 and follower flank 12 of the cutting edge as shown in FIG. 1 (b) Using the finishing chaser 13 with two threaded cutting edges E and F with a square thread shape with an acute cross section angle γ ₁ , γ ₂ against the axis of the tube, outer diameter 244.48 mm, wall thickness 13.84 After machining the tapered outer diameter of the thread under the pipe end of a seamless steel pipe of mm, as shown in Fig. 2, one pass is cut with the roughing chaser 3 and one pass with the finishing chaser 13 Processing was performed and a test was performed to form a tapered square screw at the end of the tube.
[0015]
Further, for comparison, as shown in FIG. 7 (a) as a conventional method, a cross-sectional square thread shape with an acute angle on the opposite end side to the threaded joint axis of the leading edge flank 72 and the trailing flank 73 of the cutting edge is provided. Using one machining chaser 71 with two cutting edges X and Y and machining the threaded taper outer diameter part at the pipe end, as shown in Fig. 7 (b), in three passes A test for forming a tapered square screw at the pipe end was performed by cutting the screw.
[0016]
Then, the chaser life, thread cutting efficiency, and chaser intensity of the method of the present invention and the conventional method were investigated. The results are shown in FIGS. Note that the chaser life is the number of threaded pipe ends per finisher chaser, the thread cutting efficiency is the number of threaded pipe ends per hour, the chaser unit is the chaser price per life, and the conventional method is 100 It is shown by the index.
[0017]
As shown in FIGS. 3 to 5, in the method of the present invention, the chaser life is extended by about three times compared to the conventional method, and the thread cutting efficiency is improved by about 11% compared to the conventional method. The unit could be reduced by about 30% compared with the conventional method.
[0018]
【The invention's effect】
Cutting method of tapered square screw of the present invention, the anti-tube end angle beta ₂ is obtuse or a right angle relative to the axis of the threaded joint follow flank of the cutting edge, anti pipe end with respect to the axis of the stabbing flank of the threaded joint side angle beta ₁ is subjected to rough threading of one or more times with Cheza for rough machining with a cutting edge of an acute buttress thread shape 3 mountain above. Then, the anti-tube end-side angle gamma ₁ with respect to the axis of the threaded joint of the stabbing flank cutting edge are identical and counter tube end angle alpha ₁ relative to the axis of the threaded joint of the clearance flank of the thread of the tapered square screw, and the chase flank counter pipe end side angles gamma ₂ with respect to the axis of the threaded joint, the anti-tube end angle alpha ₂ of the same screws with respect to the axis of the pressure flank of the threaded joint of the threads of the tapered square thread profile By performing finishing screw machining once or more using a finishing chaser having one or more cutting edges, the thread cutting efficiency can be improved, the average life of the chaser can be extended, and the basic unit of the screw chaser can be reduced. be able to.
[Brief description of the drawings]
FIG. 1 shows a chaser of the method of the present invention used in an embodiment, wherein FIG. 1 (a) is a roughing chaser, and FIG. 1 (b) is a side view of a finishing chaser.
FIG. 2 is a detailed explanatory view of a thread cutting method in two passes by a chaser according to the present invention used in an embodiment.
FIG. 3 is a graph showing a comparison of the chaser lifetime between the method of the present invention and the conventional method in an example.
FIG. 4 is a graph showing a comparison of thread cutting efficiency between the method of the present invention and the conventional method in Examples.
FIG. 5 is a graph showing a comparison of the basic unit of chaser between the method of the present invention and the conventional method in Examples.
6A and 6B are explanatory views of a tapered square screw, wherein FIG. 6A is a schematic cross-sectional view of a tube end tapered square screw portion, and FIG. 6B is a cross-sectional explanatory view of a square screw.
7A and 7B are explanatory views of a conventional chaser and screw cutting method, wherein FIG. 7A is a side view of the chaser, and FIG. 7B is a detailed explanatory view of a screw cutting method in three passes.
FIG. 8 is a detailed explanatory view of a conventional chaser, in which (a) is a side view, (b) is a front view, and (c) is a bottom view.
9A and 9B are explanatory diagrams of grinder grinding of a conventional chaser, where FIG. 9A is a side view and FIG. 9B is a bottom view.
[Explanation of symbols]
1, 11, 72 Advance side
2, 12, 73
3 Rough chaser
13 Finishing chaser
51 steel pipe
52 Thread
53 Playing Frank
54 Pressure side flank
71, 81 Chesa
82 Grinder
A, B, C, D, X, Y
E, F, X, Y Thread cutting edge θ Clearance angle

Claims (1)

In a thread cutting method of a threaded joint product with a tapered square thread shape with acute angles α ₁ and α ₂ with respect to the thread joint axis of the thread play side flank and pressure side flank After machining the diameter, the anti-pipe end side angle β _{2 of} the cutting edge follower flank with respect to the screw joint axis is obtuse or right-angled, and the anti-pipe end side angle β ₁ with respect to the lead side flank thread joint axis is acute. After the rough threading is performed one or more times using a roughing chaser having three or more serrated thread-shaped cutting edges, the angle γ ₁ on the opposite end of the cutting edge leading side flank with respect to the threaded joint axis There the same as the anti-tube end angle alpha ₁ relative to the axis of the threaded joint of the clearance flank of the thread of the tapered square screw, and the counter-pipe end side angles gamma ₂ with respect to the axis of the follow-side flank of the threaded joint Tapered square thread screw It is characterized in that the finishing thread machining is performed at least once using a finishing chaser having at least one thread-shaped cutting edge having the same angle α _{2 as the} counter pipe end side angle α ₂ with respect to the axis of the threaded joint of the thread pressure side flank. Cutting method for tapered square screw.

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