CN210888836U

CN210888836U - Anti-fatigue threaded joint of sleeve

Info

Publication number: CN210888836U
Application number: CN201921631081.XU
Authority: CN
Inventors: 胡志立; 李小兵; 谢凯意; 吴丹; 张垂贵; 李建亮; 付强; 李健; 冉雪辉; 胡新太; 刘功威
Original assignee: Hengyang Valin Steel Tube Co Ltd
Current assignee: Hengyang Valin Steel Tube Co Ltd
Priority date: 2019-09-27
Filing date: 2019-09-27
Publication date: 2020-06-30
Anticipated expiration: 2029-09-27

Abstract

The utility model provides an antifatigue sheathed tube screwed joint for the connection of pipeline, include: the male end is provided with an external thread joint; the female end is provided with an internal thread joint, and the male end is in threaded connection with the female end; wherein, female end is provided with at least one stress release structure to increase the fatigue strength of screwed joint. The technical scheme of the utility model the problem of the casing pipe screwed joint fatigue resistance among the prior art has been solved effectively.

Description

Anti-fatigue threaded joint of sleeve

Technical Field

The utility model relates to a technical field of piping installation particularly, relates to an antifatigue sheathed tube screwed joint.

Background

With the gradual depletion of land oil and gas resources, ocean oil and gas resources are developed in a large quantity, threaded joints such as deep-sea ore-raising pipes, drilling marine risers and production oil casings bear various loads of threaded joints of the land oil and gas pipes, and bear cyclic dynamic loads caused by ocean waves and ocean currents, so that the marine threaded joints are required to have fatigue resistance and prevent seawater from entering the threads to cause stress corrosion besides the performance of the land oil and gas joints.

The existing standard API sleeve joint and the special threaded joint have large stress concentration coefficients, and the joints have no fatigue resistance.

Chinese patent CN203925329 discloses a two-stage sealing threaded joint, which is technically designed with a special inner sealing structure and an outer sealing structure, but has low connection strength and no fatigue resistance.

Chinese patent CN107503694 discloses a utility model patent named "oil, sleeve threaded joint", this patent technology screw thread is the partial trapezoidal structure of modified, and seal structure has adopted the second interior seal face to be the cylinder, and the interior seal face is the structure of sphere, and this seal structure can remain stable sealing performance under the sleeve atress state, but production and processing and detection difficulty, seal structure accident damage easily moreover.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a threaded joint of antifatigue sleeve pipe to the sleeve pipe threaded joint who solves among the prior art does not possess the problem of fatigue resistance.

In order to achieve the above object, the present invention provides a threaded joint of fatigue-resistant casing for connection of pipelines, including: the male end is provided with an external thread joint; the female end is provided with an internal thread joint, and the male end is in threaded connection with the female end; wherein, female end is provided with at least one stress release structure to increase the fatigue strength of screwed joint.

Further, form a plurality of connection structure after public end and the cooperation of female end, a plurality of connection structure include: the outer sealing structure is arranged at the end part close to the female end; the stress release structure is arranged on one side of the end part of the outer sealing structure close to the male end; the thread engagement structure is arranged on one side, away from the outer sealing structure, of the stress release structure; the inner sealing structure is arranged on one side of the thread engagement structure, which is far away from the outer sealing structure; and the shoulder structure is arranged on one side, away from the outer sealing structure, of the inner sealing structure and is positioned at the end position of the male end.

Further, the male end includes: the large end part of the pipe body is arranged at the position far away from the end part of the male end; the external thread part is arranged on one side of the large end part of the pipe body close to the end part of the male end; the nose end part is arranged at the end part of the male end and is positioned at one side of the external thread part close to the end part of the male end.

Furthermore, an outer sealing conical surface, a first inclined surface, a first cylindrical surface and a first inverted inclined surface are respectively arranged at the large end part of the pipe body from the inner side of the male end to the end part; the outer sealing conical surface is a male end part of the outer sealing structure, and the first inclined surface, the first cylindrical surface and the first inverted inclined surface are matched to form the male end part of the stress release structure.

Further, a transition circular arc is arranged between at least part of two adjacent surfaces on the large end part of the pipe body.

Furthermore, a transition circular arc is arranged between the outer sealing conical surface and the first inclined surface, the radius is R1, and R1 is more than or equal to 8mm and less than or equal to 12 mm; a transition circular arc is arranged between the first inclined plane and the first cylindrical surface, the radius of the transition circular arc is R2, and R2 is more than or equal to 8mm and less than or equal to 12 mm; a transition circular arc is arranged between the first cylindrical surface and the first reverse inclined surface, the radius is R3, and R3 is more than or equal to 10mm and less than or equal to 12 mm.

Furthermore, the included angle between the outer sealing conical surface and the axis of the tube body is α 1 degrees, α 1 degrees is more than or equal to 1.5 degrees and less than or equal to 5 degrees, the included angle between the first inclined plane and the axis of the tube body is α 2 degrees, α 2 degrees is more than or equal to 10 degrees and less than or equal to 20 degrees, and the included angle between the axis of the tube body of the first inverted inclined plane is α 3 degrees, and α 3 degrees is more than or equal to 10 degrees and less than or equal to 20 degrees.

Furthermore, a second inverted inclined plane, a second cylindrical surface, a second inclined plane, a first inner sealing surface, a third cylindrical surface, an outer guide inclined plane and a shoulder surface are respectively arranged at the end part of the nose from the inner side of the male end to the end part; the first inner sealing surface and the third cylindrical surface are matched to form a male end part of the inner sealing structure, and the outer guide inclined surface and the shoulder surface are matched to form a male end part of the shoulder structure.

Further, a transition circular arc is arranged between two adjacent surfaces at least partially on the nose end part.

Furthermore, a transition circular arc is arranged between the second cylindrical surface and the second inclined surface, the radius is R4, and R4 is more than or equal to 2mm and less than or equal to 6 mm; a transition arc is arranged between the second inclined surface and the first inner sealing surface, the radius is R5, and R5 is more than or equal to 1mm and less than or equal to 3 mm; a transition arc is arranged between the first inner sealing surface and the third cylindrical surface, the radius is R6, and R6 is more than or equal to 1mm and less than or equal to 3 mm; a transition arc is arranged between the third cylindrical surface and the outer guide inclined surface, the radius of the transition arc is R7, and R7 is more than or equal to 1mm and less than or equal to 3 mm; a transition circular arc is arranged between the outer guide inclined plane and the shoulder surface, the radius is R8, and R8 is more than or equal to 0.6mm and less than or equal to 2 mm.

Furthermore, the included angle between the second inverted inclined plane and the axis of the pipe body is α degrees and is not less than 20 degrees and α degrees and not more than 30 degrees, the included angle between the second inclined plane and the axis of the pipe body is α degrees and is not less than 15 degrees and is not less than α degrees and not more than 30 degrees, the included angle between the first inner sealing surface and the axis of the pipe body is α degrees and is not less than 8 degrees and α degrees and not more than 25 degrees, the included angle between the outer guide inclined plane and the axis of the pipe body is α degrees and is not less than 10 degrees and not more than α degrees and not more than 30 degrees, the included angle between the shoulder surface and the vertical plane of the axis of the pipe body is α degrees.

Further, the female end includes: the stress release part is arranged in the middle of the female end; the internal thread part is arranged on one side of the stress release part far away from the end part of the female end; the sealing shoulder part is arranged on one side, away from the stress release part, of the internal thread part; the outer sealing part is arranged on the inner side of the female end close to the end part and is positioned on one side, away from the internal thread part, of the stress releasing part.

Further, the stress relieving portion includes: the outer groove is arranged on the outer side of the female end; the inner groove is arranged on the inner side of the female end; wherein, outer recess sets up with interior recess is crisscross, and the interior recess is in one side that outer recess is close to the tip of female end.

Furthermore, a third inclined plane, a fourth cylindrical surface, a fourth inclined plane, a first arc surface and a fifth inclined plane are respectively arranged on the outer groove from one side close to the end part of the female end to one side far away from the end part of the female end; the third inclined plane, the fourth cylindrical surface and the fourth inclined plane are matched and then matched with the inner grooves, and the fourth inclined plane, the first arc surface and the fifth inclined plane are matched and then form groove-shaped structures which are sunken towards the inner side of the pipe body.

Further, a transition circular arc is arranged between two adjacent surfaces of at least part of the outer groove.

Furthermore, a transition arc is arranged between the fourth cylindrical surface and the first arc surface, the radius is R9, and R9 is more than or equal to 8mm and less than or equal to 12 mm; the radius of the first arc surface is R10, R10 is more than or equal to 30mm and less than or equal to 50 mm; a transition arc is arranged between the fifth inclined plane and the outer surface of the female end, the radius is R11, and R11 is more than or equal to 10mm and less than or equal to 30 mm.

Furthermore, the included angle between the third inclined plane and the axis of the pipe body is β 1 degrees and is not less than 2 degrees and not more than β 1 degrees and not more than 6 degrees, the included angle between the fourth inclined plane and the axis of the pipe body is β 2 degrees and is not less than 8 degrees and not more than β 2 degrees and not more than 20 degrees, and the included angle between the fifth inclined plane and the axis of the pipe body is β 3 degrees and is not less than 5 degrees and not more than β 3 degrees and not more than 15 degrees.

Furthermore, a sixth inclined plane, a second arc surface and a seventh inclined plane are respectively arranged on the inner groove from one side close to the end part of the female end to one side far away from the end part of the female end; and the sixth inclined plane, the second arc surface and the seventh inclined plane are matched to form a groove structure on the inner wall of the female end.

Furthermore, the radius of the second arc surface is R12, R12 is more than or equal to 20mm and less than or equal to 40mm, the included angle between the sixth inclined surface and the axis of the pipe body is β 4, and is more than or equal to 6 degrees and less than or equal to β 4 and less than or equal to 12 degrees, and the included angle between the seventh inclined surface and the axis of the pipe body is β 5, and is more than or equal to 15 degrees and less than or equal to β 5 and less than or equal to 30 degrees.

Further, the seal shoulder portion includes: the inner sealing part is arranged on one side, away from the stress release part, of the inner threaded part; and the shoulder part is arranged on one side of the inner sealing part far away from the inner sealing part.

Furthermore, an eighth inclined surface, a fifth cylindrical surface, a ninth inclined surface, a second inner sealing surface, a sixth cylindrical surface, an inner guide inclined surface and an inner shoulder surface are respectively arranged on the sealing shoulder part from one side close to the end part of the female end to one side far away from the end part of the female end; the eighth inclined plane, the fifth cylindrical surface, the ninth inclined plane, the second inner sealing surface and the sixth cylindrical surface are matched to form an inner sealing part, and the inner guide inclined plane and the inner shoulder surface are matched to form a shoulder part.

Furthermore, a transition arc is arranged between the eighth inclined plane and the fifth cylindrical surface, the radius is R13, and R13 is more than or equal to 2mm and less than or equal to 6 mm; a transition arc is arranged between the fifth cylindrical surface and the ninth inclined surface, the radius is R14, and R14 is more than or equal to 1mm and less than or equal to 4 mm; a transition arc is arranged between the ninth inclined surface and the second inner sealing surface, the radius is R15, and R15 is more than or equal to 6mm and less than or equal to 15 mm; a transition arc is arranged between the second inner sealing surface and the sixth cylindrical surface, the radius of the transition arc is R16, and R16 is more than or equal to 1mm and less than or equal to 4 mm; a transition arc is arranged between the sixth cylindrical surface and the inner guide inclined surface, the radius of the transition arc is R17, and R17 is more than or equal to 1mm and less than or equal to 4 mm; a transition arc is arranged between the inner guide inclined plane and the inner shoulder surface, the radius is R18, and R18 is more than or equal to 0.5mm and less than or equal to 1 mm.

Furthermore, the included angle between the eighth inclined plane and the axis of the pipe body is β degrees, 10 degrees and β degrees are more than or equal to 20 degrees, the included angle between the ninth inclined plane and the axis of the pipe body is β degrees, 40 degrees and more than or equal to β degrees and more than or equal to 50 degrees, the included angle between the second inner sealing surface and the axis of the pipe body is β degrees, 8 degrees and more than or equal to β degrees and more than or equal to 25 degrees, the included angle between the inner guide inclined plane and the axis of the pipe body is β degrees, 10 degrees and more than or equal to β degrees and more than or equal to 30 degrees, and the included angle between the inner shoulder surface and the axis of the pipe body is β degrees and more.

Furthermore, a seventh cylindrical surface and a plurality of sealing units are respectively arranged on the outer sealing part from the end part of the female end to the side far away from the end part of the female end; the sealing units are matched to form a wavy structure and are provided with a plurality of top conical surfaces and a plurality of bottom conical surfaces, and the top conical surfaces are all positioned on the tenth inclined surface.

Furthermore, the bottom conical surfaces are arc-shaped surfaces, the bottom conical surfaces are provided with tangent planes which are simultaneously positioned on the eleventh inclined surface, and the tenth inclined surface is parallel to the eleventh inclined surface.

Furthermore, the included angle between the tenth inclined plane and the axis of the pipe body is β 11, and β 11 is more than or equal to 1.5 degrees and less than or equal to 5 degrees.

Furthermore, the sealing unit is provided with a twelfth inclined surface, a top conical surface, a thirteenth inclined surface, a bottom conical surface and a fourteenth inclined surface from one side close to the end part of the female end to one side far away from the end part of the female end; wherein the twelfth inclined surface, the top conical surface and the thirteenth inclined surface form a convex structure, and the thirteenth inclined surface, the bottom conical surface and the fourteenth inclined surface are concave structures from the convex structure.

Furthermore, a transition arc is arranged between the twelfth inclined surface and the top conical surface, the radius is R19, and R19 is more than or equal to 0.3mm and less than or equal to 1 mm; a transition arc is arranged between the top conical surface and the thirteenth inclined surface, the radius of the transition arc is R20, and R20 is more than or equal to 0.3mm and less than or equal to 1 mm; the bottom conical surface is of an arc structure, the radius of the bottom conical surface is R21, and R21 is more than or equal to 0.5mm and less than or equal to 1.5 mm.

Furthermore, the included angle between the twelfth inclined plane and the axis of the tube body is β 12 degrees, β 12 degrees is more than or equal to 40 degrees and less than or equal to 50 degrees, the included angle between the thirteenth inclined plane and the axis of the tube body is β 13 degrees, β 13 degrees is more than or equal to 10 degrees and less than or equal to 30 degrees, and the included angle between the fourteenth inclined plane and the axis of the tube body is β 14 degrees, and β 14 degrees is more than or equal to 40 degrees and less than or equal to 50 degrees.

Furthermore, four sealing units are arranged, the length of each sealing unit is L, and L is more than or equal to 2mm and less than or equal to 3.5 mm.

Further, a slotted hole structure is arranged between the inner sealing structure and the thread meshing structure, so that the sealing pressure distribution between the inner sealing structure and the thread meshing structure is improved.

Use the technical scheme of the utility model, the setting of stress release structure can make sleeve pipe screwed joint have certain fatigue resistance, and then makes sleeve pipe screwed joint have fatigue resistance ability. Therefore, the casing threaded joint has corresponding fatigue resistance while ensuring the connection strength, and the service performance and the service life of the casing threaded joint are improved. The technical scheme of the utility model sleeve pipe screwed joint among the prior art has solved effectively does not possess the problem of fatigue resistance.

Drawings

The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 shows a schematic structural view of an embodiment of a threaded joint of a fatigue-resistant bushing according to the invention;

fig. 2 shows a schematic structural diagram of the male end of the present invention;

FIG. 3 shows an enlarged view of the large end of the tube at A in FIG. 2;

FIG. 4 shows an enlarged view of the nose end at B in FIG. 2;

fig. 5 shows a schematic structural diagram of the female terminal of the present invention;

FIG. 6 shows an enlarged view of the seal land portion at C of FIG. 5;

FIG. 7 shows an enlarged view of the outer seal at D in FIG. 5;

fig. 8 shows an enlarged view of the sealing unit at E in fig. 7.

Wherein the figures include the following reference numerals:

10. a male end; 11. a large end of the tube body; 111. an outer sealing conical surface; 112. a first inclined plane; 113. a first cylindrical surface; 114. a first reverse slope; 12. an external threaded portion; 13. a nose end portion; 131. a second chamfer; 132. a second cylindrical surface; 133. a second inclined plane; 134. a first inner sealing surface; 135. a third cylindrical surface; 136. an outer guide ramp; 137. a shoulder surface; 20. a female end; 21. a stress relief portion; 211. an outer groove; 2111. a third inclined plane; 2112. a fourth cylindrical surface; 2113. a fourth slope; 2114. a first arc surface; 2115. a fifth bevel; 212. an inner groove; 2121. a sixth slope; 2122. a second arc surface; 2123. a seventh bevel; 22. an internal thread portion; 23. a seal land portion; 231. an eighth bevel; 232. a fifth cylindrical surface; 233. a ninth slope; 234. a second inner sealing surface; 235. a sixth cylindrical surface; 236. an inner guide slope; 237. an inner shoulder surface; 24. an outer seal portion; 241. a seventh cylindrical surface; 242. a tenth slope; 243. an eleventh bevel; 244. a twelfth inclined plane; 245. a top conical surface; 246. a thirteenth slope; 247. a bottom conical surface; 248. a fourteenth slope; 30. an outer seal structure; 40. a stress release structure; 50. a thread engagement structure; 60. a slotted hole structure; 70. an inner sealing structure; 80. a shoulder structure.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

As shown in fig. 1 to 8, a threaded joint of a fatigue-resistant casing in the present embodiment for connection of pipes includes a male end 10 and a female end 20. The male end 10 is provided with a male connector. Female end 20 is provided with a female adapter, and male end 10 is threadedly connected with female end 20. Wherein at least one stress relief structure 40 is provided on the box end 20 to increase the fatigue strength of the threaded joint.

By applying the technical scheme of the embodiment, the stress release structure 40 can enable the threaded joint of the casing to have certain fatigue resistance, so that the threaded joint of the casing has fatigue resistance. Therefore, the casing threaded joint has corresponding fatigue resistance while ensuring the connection strength, and the service performance and the service life of the casing threaded joint are improved. The technical scheme of this embodiment has solved the problem that the casing threaded joint among the prior art does not possess fatigue resistance effectively.

As shown in fig. 1 to 8, in the solution of the present embodiment, the male end 10 and the female end 20 are matched to form a plurality of connection structures, and the plurality of connection structures include an outer sealing structure 30, a stress relief structure 40, a thread engagement structure 50, an inner sealing structure 70 and a shoulder structure 80. The outer sealing structure 30 is disposed at an end position proximate the female end 20. The strain relief structure 40 is disposed on the side of the end of the outer seal structure 30 proximate the male end 10. The thread engagement structure 50 provides a side of the strain relief structure 40 remote from the outer seal structure 30. The inner seal structure 70 is disposed on a side of the thread engagement structure 50 remote from the outer seal structure 30. The shoulder structure 80 is arranged on the side of the inner seal structure 70 remote from the outer seal structure 30 and in the end position of the male end 10. The structure can ensure the fatigue resistance of the threaded joint of the sleeve and simultaneously ensure that the threaded joint of the sleeve has better sealing property and connection strength. The male end 10 and the female end 20 may be formed by machining a pipe or a coupling.

As shown in fig. 1 to 8, in the present embodiment, the male end 10 includes a tube body large end portion 11, an external thread portion 12, and a nose end portion 13. The large end 11 of the tube is located at a position remote from the end of the male end 10. The male screw portion 12 is provided on the end portion side of the large end portion 11 of the pipe body near the male end 10. The nose portion 13 is provided at the end of the male end 10 on the side of the male screw portion 12 near the end of the male end 10. The arrangement of the large end part 11 of the pipe body in the structure is used for matching with the stress releasing structure 40, and can also be used as a part of the stress releasing structure 40, and the arrangement of the nose end part 13 is used for improving the stability of the connection of the pipe body.

As shown in fig. 1 to 8, in the technical solution of the present embodiment, the large end portion 11 of the pipe body is provided with an outer sealing conical surface 111, a first inclined surface 112, a first cylindrical surface 113, and a first reverse inclined surface 114 from the inner side of the male end 10 to the end portion. The outer sealing conical surface 111 is a male end portion of the outer sealing structure 30, and the first inclined surface 112, the first cylindrical surface 113 and the first inverted inclined surface 114 cooperate to form a male end portion of the stress relief structure 40. At least part of the adjacent two surfaces on the large end part 11 of the pipe body are provided with transition arcs. The above structure can prevent the stress concentration from occurring in the portion while ensuring the performance of the stress relieving structure 40.

Wherein, a transition circular arc is arranged between the outer sealing conical surface 111 and the first inclined surface 112, the radius is R1, and R1 is more than or equal to 8mm and less than or equal to 12 mm. A transition circular arc is arranged between the first inclined plane 112 and the first cylindrical surface 113, the radius is R2, and R2 is more than or equal to 8mm and less than or equal to 12 mm. A transition circular arc is arranged between the first cylindrical surface 113 and the first reverse inclined surface 114, the radius is R3, and R3 is more than or equal to 10mm and less than or equal to 12 mm. The above structure can further reduce the occurrence of stress concentration on the male end 10.

As shown in fig. 1 to 8, in the technical solution of the present embodiment, the included angle between the outer sealing conical surface 111 and the tube axis is α 1, and 1.5 ° or more and α 1 ° or more and 5 ° or less, the included angle between the first inclined surface 112 and the tube axis is α 2, and 10 ° or more and α 2 ° or more and 20 ° or less, the included angle between the first inverted inclined surface 114 and the tube axis is α 3, and 10 ° or more and α 3 ° or more and 20 ° or less, and the structure mentioned above can make the large end portion 11 of the tube form an annular groove to better fit the stress releasing structure 40.

As shown in fig. 1 to 8, in the solution of the present embodiment, the nose end portion 13 is provided with a second reverse inclined surface 131, a second cylindrical surface 132, a second inclined surface 133, a first inner sealing surface 134, a third cylindrical surface 135, an outer guide inclined surface 136, and a shoulder surface 137 from the inside of the male end 10 to the end portion. Wherein second chamfer 131, second cylindrical surface 132 and second chamfer 133 cooperate to form a groove-like configuration, first inner sealing surface 134 and third cylindrical surface 135 cooperate to form a male end portion of inner seal 70, and outer pilot chamfer 136 and shoulder surface 137 cooperate to form a male end portion of shoulder 80. The above-described structure as the male end portion of the inner seal structure 70 and the male end portion of the shoulder structure 80 can improve the sealability of the connected box threaded joint while having higher stability.

As shown in fig. 1 to 8, in the solution of the present embodiment, a transition arc is provided on the nose end portion 13 at least partially between two adjacent faces. A transition arc is arranged between the second cylindrical surface 132 and the second inclined surface 133, the radius is R4, and R4 is more than or equal to 2mm and less than or equal to 6 mm. A transition circular arc is arranged between the second inclined surface 133 and the first inner sealing surface 134, the radius is R5, and R5 is more than or equal to 1mm and less than or equal to 3 mm. A transition circular arc is arranged between the first inner sealing surface 134 and the third cylindrical surface 135, the radius is R6, and R6 is more than or equal to 1mm and less than or equal to 3 mm. A transition arc is arranged between the third cylindrical surface 135 and the outer guide inclined surface 136, the radius is R7, and R7 is more than or equal to 1mm and less than or equal to 3 mm. A transition circular arc is arranged between the outer guide inclined surface 136 and the shoulder surface 137, the radius is R8, and R8 is more than or equal to 0.6mm and less than or equal to 2 mm. The above structure can further reduce the occurrence of stress concentration on the male end 10. And to provide a tighter fit between the male end 10 and the female end 20.

As shown in fig. 1 to 8, in the technical solution of this embodiment, the included angle between the second inverted slope 131 and the axis of the pipe body is α 4, and 20 ° or more and α 4 or less and 30 ° or less, the included angle between the second slope 133 and the axis of the pipe body is α 5, and 15 ° or more and α 5 or less and 30 ° or less, the included angle between the first inner sealing surface 134 and the axis of the pipe body is α 6, and 8 ° or more and α 6 or less and 25 ° or less, the included angle between the outer guide slope 136 and the axis of the pipe body is α 7, and 10 ° or more and α 7 or less and 30 ° or less, the included angle between the shoulder surface 137 and the vertical plane of the axis of the pipe body is α 8, and 10 ° or more and α 8 or less and 20 ° or less.

As shown in fig. 1 to 8, in the present embodiment, the female end 20 includes a stress relief portion 21, an internal thread portion 22, a seal shoulder portion 23, and an external seal portion 24. A strain relief 21 is provided in the middle of the female end 20. The female screw 22 is provided on the side of the stress relief portion 21 away from the end of the female end 20. A seal shoulder portion 23 is provided on a side of the female screw portion 22 remote from the stress relief portion 21. The outer seal portion 24 is provided inside the female end 20 near the end, and the outer seal portion 24 is on a side of the stress relief portion 21 away from the internal thread portion 22. The above-described structure may correspond to the structure of the female end 20 and the male end 10 to facilitate the formation of the outer seal structure 30, the strain relief structure 40, the thread engagement structure 50, the inner seal structure 70, and the shoulder structure 80.

As shown in fig. 1 to 8, in the present embodiment, the stress relief portion 21 includes an outer groove 211 and an inner groove 212. An outer groove 211 is provided outside the female end 20. An inner groove 212 is provided inboard of the female end 20. Wherein, the outer grooves 211 and the inner grooves 212 are arranged alternately, and the inner grooves 212 are arranged at one side of the end part of the outer grooves 211 close to the female end 20. The structure can better release stress.

As shown in fig. 1 to 8, in the solution of the present embodiment, the outer groove 211 is respectively provided with a third inclined surface 2111, a fourth cylindrical surface 2112, a fourth inclined surface 2113, a first arc surface 2114 and a fifth inclined surface 2115 from a side close to the end of the female end 20 to a side far from the end of the female end 20. The third inclined surface 2111, the fourth cylindrical surface 2112 and the fourth inclined surface 2113 are matched and then matched with the inner groove 212, and the fourth inclined surface 2113, the first arc surface 2114 and the fifth inclined surface 2115 are matched and then form a groove-shaped structure which is sunken towards the inner side of the pipe body. The above structure can release the stress applied to the outside of the female end 20, and the stress corresponding to the structure of the partial male end 10 can also be released.

As shown in fig. 1 to 8, in the solution of the present embodiment, a transition arc is disposed between two adjacent faces of the outer groove 211 at least partially. A transition arc is arranged between the fourth cylindrical surface 2112 and the first arc surface 2114, the radius is R9, and R9 is more than or equal to 8mm and less than or equal to 12 mm. The radius of the first arc surface 2114 is R10, and R10 is more than or equal to 30mm and less than or equal to 50 mm. A transition arc is arranged between the fifth inclined surface 2115 and the outer surface of the female end 20, the radius is R11, and R11 is more than or equal to 10mm and less than or equal to 30 mm. The above structure can further improve the stress release effect.

As shown in fig. 1 to 8, in the solution of this embodiment, the included angle between the third inclined surface 2111 and the axis of the pipe body is β 1, and 2 ° or more and β 1 ° or less and 6 ° or less, the included angle between the fourth inclined surface 2113 and the axis of the pipe body is β 2 and 8 ° or more and β 2 ° or less and 20 ° or less, the included angle between the fifth inclined surface 2115 and the axis of the pipe body is β 3 and 5 ° or more and β 3 ° or less and 15 ° or less, and the above structure can be better matched with the outer groove 211.

As shown in fig. 1 to 8, in the solution of the present embodiment, the inner groove 212 is respectively provided with a sixth inclined surface 2121, a second circular arc surface 2122 and a seventh inclined surface 2123 from a side close to the end of the female end 20 to a side far from the end of the female end 20. The sixth inclined surface 2121, the second arc surface 2122 and the seventh inclined surface 2123 cooperate to form a groove structure on the inner wall of the female end 20. The above structure can relieve stress applied to the inside of the female end 20.

As shown in fig. 1 to 8, in the solution of this embodiment, the radius of the second circular arc surface 2122 is R12, R12 is 20mm or more and 40mm or less, the included angle between the sixth inclined surface 2121 and the axis of the pipe body is β 4, and β 4 is 6 ° or more and 12 ° or less, the included angle between the seventh inclined surface 2123 and the axis of the pipe body is β 5, and β 5 is 15 ° or more and 30 ° or less.

As shown in fig. 1 to 8, in the solution of the present embodiment, the seal shoulder portion 23 includes an inner seal portion and a shoulder portion. The inner seal portion is provided on a side of the internal thread portion 22 remote from the stress relief portion 21. The shoulder portion is disposed on a side of the inner seal portion remote from the inner seal portion. The structure can improve the sealing performance of the connected threaded joint of the sleeve and has higher stability. This configuration corresponds to the nose end 13 of the male end 10.

As shown in fig. 1 to 8, in the solution of the present embodiment, the sealing shoulder 23 is provided with an eighth inclined surface 231, a fifth cylindrical surface 232, a ninth inclined surface 233, a second inner sealing surface 234, a sixth cylindrical surface 235, an inner guiding inclined surface 236 and an inner shoulder surface 237 from a side close to the end of the female end 20 to a side far from the end of the female end 20. Wherein the eighth inclined surface 231, the fifth cylindrical surface 232, the ninth inclined surface 233, the second inner sealing surface 234 and the sixth cylindrical surface 235 cooperate to form an inner sealing portion, and the inner guiding inclined surface 236 and the inner shoulder surface 237 cooperate to form a shoulder portion. The structure further improves the stability of the connected threaded joint of the sleeve while ensuring the sealing property.

As shown in fig. 1 to 8, in the technical solution of the present embodiment, a transition arc is disposed between the eighth inclined surface 231 and the fifth cylindrical surface 232, and the radius is R13, and R13 is greater than or equal to 2mm and less than or equal to 6 mm. A transition circular arc is arranged between the fifth cylindrical surface 232 and the ninth inclined surface 233, the radius is R14, and R14 is more than or equal to 1mm and less than or equal to 4 mm. A transition circular arc is arranged between the ninth inclined surface 233 and the second inner sealing surface 234, the radius is R15, and R15 is more than or equal to 6mm and less than or equal to 15 mm. A transition circular arc is arranged between the second inner sealing surface 234 and the sixth cylindrical surface 235, the radius is R16, and R16 is more than or equal to 1mm and less than or equal to 4 mm. A transition arc is arranged between the sixth cylindrical surface 235 and the inner guide inclined surface 236, the radius is R17, and R17 is more than or equal to 1mm and less than or equal to 4 mm. A transition circular arc is arranged between the inner guide inclined plane 236 and the inner shoulder surface 237, the radius is R18, and R18 is more than or equal to 0.5mm and less than or equal to 1 mm. The above structure can prevent the concentration of stress on the female terminal 20.

As shown in fig. 1 to 8, in the solution of this embodiment, the angle between the eighth inclined surface 231 and the axis of the pipe body is β 6, and 10 ° β 6 is 20 ° or less, the angle between the ninth inclined surface 233 and the axis of the pipe body is β 7, and 40 ° β 7 is 50 ° or less, the angle between the second inner sealing surface 234 and the axis of the pipe body is β 8, and 8 ° β 8 is 25 ° or less, the angle between the inner guide inclined surface 236 and the axis of the pipe body is β 9, and 10 ° β 9 is 30 ° or less, the angle between the inner shoulder surface 237 and the axis of the pipe body is β 10, and 10 ° β 10 is 20 ° or less, which can make the mating between the female end 20 and the male end 10 more stable and reliable.

As shown in fig. 1 to 8, in the solution of the present embodiment, the outer sealing portion 24 is provided with a seventh cylindrical surface 241 and a plurality of sealing units from the end of the female end 20 to the side far away from the end of the female end 20. The plurality of sealing units cooperate to form a wave structure and have a plurality of top tapers 245 and a plurality of bottom tapers 247, each of the plurality of top tapers 245 being on the tenth slope 242. The above structure can further improve the sealability of the threaded joint while protecting the stress relieving structure 40.

As shown in fig. 1 to 8, in the solution of the present embodiment, the bottom tapered surfaces 247 are arc-shaped surfaces, the bottom tapered surfaces 247 have a cut surface simultaneously on the eleventh inclined surface 243, and the tenth inclined surface 242 is parallel to the eleventh inclined surface 243. The above structure can further improve the sealing strength of the outer seal 24.

As shown in fig. 1 to 8, in the solution of the present embodiment, the included angle between the tenth inclined plane 242 and the axis of the pipe body is β 11, and 1.5 ° to β 11 ° to 5 °.

As shown in fig. 1 to 8, in the solution of the present embodiment, the sealing unit is provided with a twelfth inclined surface 244, a top tapered surface 245, a thirteenth inclined surface 246, a bottom tapered surface 247, and a fourteenth inclined surface 248 from a side close to the end of the female end 20 to a side far from the end of the female end 20. Wherein the twelfth inclined surface 244, the top tapered surface 245 and the thirteenth inclined surface 246 form a convex structure, and the thirteenth inclined surface 246, the bottom tapered surface 247 and the fourteenth inclined surface 248 are concave structure therefrom. The structure can enable the sealing unit to have better sealing performance.

As shown in fig. 1 to 8, in the technical solution of the present embodiment, a transition arc is disposed between the twelfth inclined surface 244 and the top conical surface 245, and the radius is R19, and R19 is greater than or equal to 0.3mm and less than or equal to 1 mm. A transition circular arc is arranged between the top conical surface 245 and the thirteenth inclined surface 246, the radius is R20, and R20 is more than or equal to 0.3mm and less than or equal to 1 mm. The bottom conical surface 247 is of an arc structure, the radius of the bottom conical surface 247 is R21, and R21 is more than or equal to 0.5mm and less than or equal to 1.5 mm. The structure can further improve the sealing performance of the outer sealing part 24 and avoid the stress concentration of the outer sealing part 24.

As shown in fig. 1 to 8, in the solution of the present embodiment, the included angle between the twelfth inclined surface 244 and the axis of the pipe body is β 12, and 40 ° or more and β 12 or less and 50 ° or less, the included angle between the thirteenth inclined surface 246 and the axis of the pipe body is β 13, and 10 ° or more and β 13 or less and 30 ° or less, the included angle between the fourteenth inclined surface 248 and the axis of the pipe body is β 14, and 40 ° or more and β 14 or less and 50 ° or less, and the above structure further improves the sealing strength of the outer sealing portion 24.

As shown in FIGS. 1 to 8, in the technical solution of the present embodiment, four sealing units are provided, the length of the sealing unit is L, and L is greater than or equal to 2mm and less than or equal to 3.5 mm. The above-described structure may provide the outer seal 24 with a four-layer seal, which may better protect the stress relief structure 40 while improving sealing performance.

As shown in fig. 1 to 8, in the solution of the present embodiment, a slot structure 60 is provided between the inner seal structure 70 and the thread engagement structure 50 to improve the seal pressure distribution between the inner seal structure 70 and the thread engagement structure 50. The above structure can improve the sealing pressure distribution between the inner seal structure 70 and the thread engagement structure 50, and improve the overall performance of the threaded joint for casing.

The specific implementation example is as follows:

the pipe body in the embodiment adopts a 244.48 × 11.99.99 mm-specification sleeve pipe, the steel grade is P110, the API standard is adopted to specify the outer diameter of the coupling, and the material performance meets the API standard requirement.

The geometric parameters of the male thread joint are α 1 ═ 3 °, R1 ═ 10mm, α 2 ═ 15 °, R2 ═ 10mm, R3 ═ 10mm, α 3 ═ 15 °, α 4 ═ 25 °, R4 ═ 4mm, α 5 ═ 20 °, R5 ═ 2mm, α 6 ═ 10 °, R6 ═ 2mm, R7 ═ 2mm, α 7 ═ 25 °, R8 ═ 1mm, and α 8 ═ 15 °.

β1＝4°，R9＝10mm，β2＝15°，R10＝45mm，β3＝15°，R11＝20mm。β4＝10°，R12＝30mm，β5＝25°。β6＝20°，R13＝4mm，R14＝2mm，β7＝45°，R15＝10mm，β8＝10°，R16＝2mm，R17＝2mm，β9＝25°，R18＝1.0mm，β10＝15°。

β11＝3°，β12＝45°，R19＝0.5mm，R20＝0.5mm，β13＝15°，R21＝0.8mm，β14＝45°，L＝2.5mm。

The stress concentration coefficient of the threaded joint of the sleeve is less than 1.8, the fatigue resistance is excellent, the connection strength reaches 5313kN, the compression strength reaches 3985kN, the internal pressure sealing performance reaches more than 65Mpa, the external pressure resistance reaches more than 37Mpa, the bending resistance reaches more than 20 degrees/30 meters, the requirement of no thread gluing during 3 times of makeup and breakout is met, and the threaded joint of the sleeve has excellent internal and external sealing functions.

The utility model relates to a threaded joint of an anti-fatigue sleeve, which is a threaded joint formed by screwing a pipe body and a coupling, wherein an external thread joint is processed at the end part of the pipe, and an internal thread joint is processed at the end part of the coupling;

the threaded joint of the sleeve adopts an innovative joint structure, so that the joint has excellent fatigue resistance;

the design of the inner sealing structure 70 is adopted, so that the joint has excellent inner pressure air sealing performance;

meanwhile, the design of the outer sealing structure 30 is adopted, so that the joint has certain outer sealing capacity, and stress corrosion caused by the fact that an external medium enters a thread part is prevented.

The utility model discloses have excellent fatigue resistance, have good inner seal performance and external sealing performance simultaneously, can connect as high fatigue performance such as marine drilling riser, top casing, ore pumping pipe, riser.

From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: use the technical scheme of the utility model, stress release structure 40's setting can make casing threaded joint have certain fatigue resistance, and then makes casing threaded joint have fatigue resistance. Therefore, the casing threaded joint has corresponding fatigue resistance while ensuring the connection strength, and the service performance and the service life of the casing threaded joint are improved. The technical scheme of the utility model sleeve pipe screwed joint among the prior art has solved effectively does not possess the problem of fatigue resistance.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A threaded joint for fatigue-resistant casing for the connection of pipes, comprising:

the male end (10), wherein an external thread joint is arranged on the male end (10);

the female end (20), the female end (20) is provided with an internal thread joint, and the male end (10) is in threaded connection with the female end (20);

wherein at least one stress relief structure (40) is provided on the female end (20) to increase the fatigue strength of the threaded joint.

2. A threaded joint according to claim 1, characterized in that said male end (10) and said female end (20) cooperate to form a plurality of connection structures comprising:

an outer sealing structure (30), the outer sealing structure (30) being disposed at an end location proximate the female end (20);

a stress relief structure (40), the stress relief structure (40) being disposed on a side of an end of the outer sealing structure (30) proximate to the female end (20);

a thread engagement structure (50), the thread engagement structure (50) being disposed on a side of the stress relief structure (40) remote from the outer seal structure (30);

an inner seal structure (70), the inner seal structure (70) being disposed on a side of the thread engagement structure (50) remote from the outer seal structure (30);

a shoulder structure (80), said shoulder structure (80) being arranged on a side of said inner seal structure (70) remote from said outer seal structure (30) and in an end position of said male end (10).

3. A threaded joint of a fatigue-resistant bushing according to claim 2, characterized in that the male end (10) comprises:

a large pipe end (11), the large pipe end (11) being disposed at a position away from the end of the male end (10);

an external thread part (12), wherein the external thread part (12) is arranged on one side of the end part of the large end part (11) of the pipe body close to the male end (10);

a nose end portion (13), wherein the nose end portion (13) is arranged at the end portion of the male end (10) and is positioned at one side of the end portion, close to the male end (10), of the external thread portion (12).

4. The threaded joint of the fatigue-resistant sleeve according to claim 3, wherein the large end portion (11) of the pipe body is provided with an outer sealing conical surface (111), a first inclined surface (112), a first cylindrical surface (113) and a first reverse inclined surface (114) from the inner side of the male end (10) to the end portion;

the outer sealing conical surface (111) is a male end portion of the outer sealing structure (30), and the first inclined surface (112), the first cylindrical surface (113) and the first inverted inclined surface (114) are matched to form the male end portion of the stress release structure (40).

5. A threaded joint according to claim 4, characterized in that said tubular body big end (11) is provided with a transition arc at least partially between two adjacent faces.

6. The fatigue-resistant threaded joint of bushings according to claim 5, characterized in that a transition arc is provided between the outer sealing cone surface (111) and the first chamfer (112) with a radius R1, 8mm R1 mm 12 mm;

a transition circular arc is arranged between the first inclined surface (112) and the first cylindrical surface (113), the radius of the transition circular arc is R2, and R2 is more than or equal to 8mm and less than or equal to 12 mm;

a transition circular arc is arranged between the first cylindrical surface (113) and the first reverse inclined surface (114), the radius is R3, and R3 is more than or equal to 10mm and less than or equal to 12 mm.

7. The fatigue-resistant threaded joint of sleeve according to claim 4, wherein the angle between the outer sealing taper surface (111) and the axis of the tubular body is α 1 °, and 1.5 ° or more and α 1 ° or less and 5 ° or less;

the included angle between the first inclined plane (112) and the axis of the pipe body is α 2 degrees, and α 2 is more than or equal to 10 degrees and less than or equal to 20 degrees;

the included angle of the tube body axis of the first reverse inclined plane (114) is α 3 degrees, and α 3 is more than or equal to 10 degrees and less than or equal to 20 degrees.

8. A threaded joint according to claim 3, characterized in that the nose portion (13) is provided with a second chamfer (131), a second cylindrical surface (132), a second chamfer (133), a first inner sealing surface (134), a third cylindrical surface (135), an outer guiding chamfer (136) and a shoulder surface (137) from inside to the end of the male end (10), respectively;

wherein the second chamfer (131), the second cylindrical surface (132) and the second chamfer (133) cooperate to form a groove-like structure, the first inner sealing surface (134) and the third cylindrical surface (135) cooperate to form a male end portion of the inner seal structure (70), and the outer guide chamfer (136) and the shoulder surface (137) cooperate to form a male end portion of the shoulder structure (80).

9. A threaded joint according to a fatigue-resistant bushing according to claim 8, characterized in that the nose portion (13) is provided with a transition arc at least partially between two adjacent faces.

10. A threaded joint according to claim 9, characterized in that between said second cylindrical surface (132) and said second inclined surface (133) there is provided a transition arc with a radius R4, 2mm R4 mm 6 mm;

a transition circular arc is arranged between the second inclined surface (133) and the first inner sealing surface (134), the radius of the transition circular arc is R5, and R5 is more than or equal to 1mm and less than or equal to 3 mm;

a transition circular arc is arranged between the first inner sealing surface (134) and the third cylindrical surface (135), the radius of the transition circular arc is R6, and R6 is more than or equal to 1mm and less than or equal to 3 mm;

a transition arc is arranged between the third cylindrical surface (135) and the outer guide inclined surface (136), the radius is R7, and R7 is more than or equal to 1mm and less than or equal to 3 mm;

a transition circular arc is arranged between the outer guide inclined surface (136) and the shoulder surface (137), the radius is R8, and R8 is more than or equal to 0.6mm and less than or equal to 2 mm.

11. A threaded joint according to claim 8, characterized in that said second chamfer (131) has an angle α 4 with the axis of the tubular body, 20 ° - α 4 ° -30 °;

the included angle between the second inclined plane (133) and the axis of the pipe body is α 5 degrees, and α 5 is more than or equal to 15 degrees and less than or equal to 30 degrees;

the included angle between the first inner sealing surface (134) and the axis of the pipe body is α 6 degrees, and α 6 is more than or equal to 8 degrees and less than or equal to 25 degrees;

the included angle between the outer guide inclined plane (136) and the axis of the pipe body is α 7 degrees, and α 7 degrees is more than or equal to 10 degrees and less than or equal to 30 degrees;

the included angle between the shoulder surface (137) and the vertical plane of the axis of the pipe body is α 8 degrees, and α 8 is more than or equal to 10 degrees and less than or equal to 20 degrees.

12. A threaded joint of a fatigue-resistant bushing according to claim 1, characterized in that the female end (20) comprises:

a stress relief portion (21), the stress relief portion (21) being disposed in a middle portion of the female end (20);

a female screw portion (22), the female screw portion (22) being provided on a side of the stress relief portion (21) away from an end of the female end (20);

a seal shoulder portion (23), the seal shoulder portion (23) being provided on a side of the internal thread portion (22) away from the stress relief portion (21);

the outer sealing part (24) is arranged on the inner side of the female end (20) close to the end, and the outer sealing part (24) is arranged on one side, away from the internal thread part (22), of the stress releasing part (21).

13. A threaded joint of a fatigue-resistant bushing according to claim 12, characterized in that the stress relief (21) comprises:

an outer groove (211), the outer groove (211) being disposed outside the female end (20);

an inner groove (212), the inner groove (212) disposed inboard of the female end (20);

the outer grooves (211) and the inner grooves (212) are arranged in a staggered mode, and the inner grooves (212) are located on one side of the end portion, close to the female end (20), of the outer grooves (211).

14. The threaded joint of the fatigue-resistant bushing according to claim 13, wherein the outer groove (211) is provided with a third inclined surface (2111), a fourth cylindrical surface (2112), a fourth inclined surface (2113), a first arc surface (2114) and a fifth inclined surface (2115) from a side close to the end of the female end (20) to a side far from the end of the female end (20), respectively;

the third inclined surface (2111), the fourth cylindrical surface (2112) and the fourth inclined surface (2113) are matched and then are matched with the inner groove (212), and the fourth inclined surface (2113), the first arc surface (2114) and the fifth inclined surface (2115) are matched and then form a groove-shaped structure which is sunken towards the inner side of the pipe body.

15. A threaded joint according to a fatigue-resistant sleeve according to claim 14, wherein the outer groove (211) is provided with a transition arc at least partially between two adjacent faces.

16. A threaded joint according to claim 15, characterized in that between said fourth cylindrical surface (2112) and said first circular arc surface (2114) there is provided a transition circular arc with a radius R9, 8mm R9 mm 12 mm;

the radius of the first arc surface (2114) is R10, and R10 is more than or equal to 30mm and less than or equal to 50 mm;

a transition arc is arranged between the fifth inclined surface (2115) and the outer surface of the female end (20), the radius is R11, and R11 is more than or equal to 10mm and less than or equal to 30 mm.

17. A threaded joint according to claim 14, wherein the third chamfer (2111) is at an angle β 1 ° with the axis of the tubular body, 2 ° β 1 ° 6 °;

the included angle between the fourth inclined surface (2113) and the axis of the pipe body is β 2 degrees, and β 2 is more than or equal to 8 degrees and less than or equal to 20 degrees;

the included angle between the fifth inclined surface (2115) and the axis of the pipe body is β 3, and β 3 is more than or equal to 5 degrees and less than or equal to 15 degrees.

18. A threaded joint according to a fatigue-resistant sleeve according to claim 13, wherein the inner groove (212) is provided with a sixth chamfer (2121), a second circular arc surface (2122) and a seventh chamfer (2123) respectively from a side close to the end of the female end (20) to a side far from the end of the female end (20);

the sixth inclined surface (2121), the second arc surface (2122) and the seventh inclined surface (2123) are matched to form a groove structure on the inner wall of the female end (20).

19. A threaded joint of fatigue-resistant sleeve according to claim 18, wherein the radius of the second circular arc surface (2122) is R12, 20mm ≦ R12 ≦ 40 mm;

the included angle between the sixth inclined plane (2121) and the axis of the pipe body is β 4 degrees, and β 4 degrees is more than or equal to 6 degrees and less than or equal to 12 degrees;

the included angle between the seventh inclined surface (2123) and the axis of the pipe body is β 5 degrees, and β 5 degrees is more than or equal to 15 degrees and less than or equal to 30 degrees.

20. A threaded joint of fatigue-resistant bushings according to claim 12, characterized in that the sealing shoulder (23) comprises:

an internal seal portion provided on a side of the internal thread portion (22) away from the stress relief portion (21);

a shoulder portion disposed on a side of the inner seal portion distal from the inner seal portion.

21. A threaded joint according to a fatigue-resistant sleeve according to claim 20, wherein the sealing shoulder (23) is provided with an eighth chamfer (231), a fifth cylindrical surface (232), a ninth chamfer (233), a second inner sealing surface (234), a sixth cylindrical surface (235), an inner guiding chamfer (236) and an inner shoulder surface (237), respectively, from the side close to the end of the box end (20) to the side far from the end of the box end (20);

wherein the eighth ramp (231), the fifth cylindrical surface (232), the ninth ramp (233), the second inner sealing surface (234), and the sixth cylindrical surface (235) cooperate to form an inner seal, and the inner guide ramp (236) and the inner shoulder surface (237) cooperate to form a shoulder.

22. A threaded joint according to claim 21, characterized in that between said eighth chamfer (231) and said fifth cylindrical surface (232) there is provided a transition arc with a radius R13, 2mm R13 mm 6 mm;

a transition arc is arranged between the fifth cylindrical surface (232) and the ninth inclined surface (233), the radius of the transition arc is R14, and R14 is more than or equal to 1mm and less than or equal to 4 mm;

a transition circular arc is arranged between the ninth inclined surface (233) and the second inner sealing surface (234), the radius of the transition circular arc is R15, and R15 is more than or equal to 6mm and less than or equal to 15 mm;

a transition circular arc is arranged between the second inner sealing surface (234) and the sixth cylindrical surface (235), the radius of the transition circular arc is R16, and R16 is more than or equal to 1mm and less than or equal to 4 mm;

a transition arc is arranged between the sixth cylindrical surface (235) and the inner guide inclined surface (236), the radius is R17, and R17 is more than or equal to 1mm and less than or equal to 4 mm;

a transition circular arc is arranged between the inner guide inclined surface (236) and the inner shoulder surface (237), the radius of the transition circular arc is R18, and R18 is more than or equal to 0.5mm and less than or equal to 1 mm.

23. A threaded joint according to claim 21, wherein the angle between the eighth chamfer (231) and the axis of the tubular body is β 6, and 10 ° ≦ β 6 ≦ 20 °;

the included angle between the ninth inclined plane (233) and the axis of the pipe body is β 7 degrees, and β 7 is more than or equal to 40 degrees and less than or equal to 50 degrees;

the included angle between the second inner sealing surface (234) and the axis of the pipe body is β 8 degrees, and β 8 is more than or equal to 8 degrees and less than or equal to 25 degrees;

the included angle between the inner guide inclined plane (236) and the axis of the pipe body is β 9 degrees, and β 9 degrees is more than or equal to 10 degrees and less than or equal to 30 degrees;

the included angle between the inner shoulder surface (237) and the axis of the pipe body is β 10, and β 10 is more than or equal to 10 degrees and less than or equal to 20 degrees.

24. A threaded joint according to a fatigue-resistant sleeve according to claim 12, characterized in that the outer seal (24) is provided with a seventh cylindrical surface (241) and a plurality of sealing units, respectively, from the end of the female end (20) to the side away from the end of the female end (20);

the sealing units are matched to form a wave structure and provided with a plurality of top conical surfaces (245) and a plurality of bottom conical surfaces (247), and the top conical surfaces (245) are all arranged on a tenth inclined surface (242).

25. The fatigue-resistant threaded joint as recited in claim 24, wherein the bottom taper surface (247) is an arc-shaped surface, a plurality of the bottom taper surfaces (247) having a cut simultaneously on an eleventh bevel surface (243), the tenth bevel surface (242) being parallel to the eleventh bevel surface (243).

26. A threaded joint according to claim 24, wherein the tenth chamfer (242) is at an angle β 11 with the axis of the tubular body of 1.5 ° β 11 ° 5 °.

27. The threaded joint of fatigue-resistant casing according to claim 24, wherein the sealing unit is provided with a twelfth chamfer (244), the top taper (245), a thirteenth chamfer (246), the bottom taper (247) and a fourteenth chamfer (248) from a side near to the end of the female end (20) to a side far from the end of the female end (20), respectively;

wherein the twelfth slope (244), the top taper (245), and the thirteenth slope (246) form a convex structure from which the thirteenth slope (246), the bottom taper (247), and the fourteenth slope (248) are recessed.

28. The fatigue-resistant threaded joint of bushings according to claim 27, characterized in that a transition arc is provided between the twelfth chamfer (244) and the top cone (245) with a radius R19, 0.3mm ≦ R19 ≦ 1 mm;

a transition circular arc is arranged between the top conical surface (245) and the thirteenth inclined surface (246), the radius of the transition circular arc is R20, and R20 is more than or equal to 0.3mm and less than or equal to 1 mm;

the bottom conical surface (247) is of an arc structure, the radius of the bottom conical surface (247) is R21, and R21 is more than or equal to 0.5mm and less than or equal to 1.5 mm.

29. A threaded joint according to claim 27, wherein the included angle of the twelfth chamfer (244) with the axis of the tubular body is β 12, and 40 ° ≦ β 12 ≦ 50 °;

the included angle between the thirteenth inclined plane (246) and the axis of the pipe body is β 13 degrees, and β 13 degrees is more than or equal to 10 degrees and less than or equal to 30 degrees;

the included angle between the fourteenth inclined surface (248) and the axis of the pipe body is β 14, and β 14 is more than or equal to 40 degrees and less than or equal to 50 degrees.

30. A threaded joint according to claim 24, characterized in that said sealing units are provided in four, said sealing units having a length L, 2mm ≦ L ≦ 3.5 mm.

31. A threaded joint of fatigue resistant bushing according to claim 2, characterized in that a slotted structure (60) is provided between the inner sealing structure (70) and the thread engagement structure (50) to improve the sealing pressure distribution between the inner sealing structure (70) and the thread engagement structure (50).