CN119777747A - Internal thread connector - Google Patents
Internal thread connector Download PDFInfo
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- CN119777747A CN119777747A CN202311295584.5A CN202311295584A CN119777747A CN 119777747 A CN119777747 A CN 119777747A CN 202311295584 A CN202311295584 A CN 202311295584A CN 119777747 A CN119777747 A CN 119777747A
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- thread
- internal thread
- conical surface
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Abstract
本发明提供的一种内螺纹接头，包括API圆螺纹本体，所述API圆螺纹本体包括第一内螺纹段、圆锥面段和第二内螺纹段，其中，第一内螺纹段、圆锥面段和第二内螺纹段自API圆螺纹本体的端部至底部依次布置；该结构在API圆螺纹本体受力均匀且较小的位置切削了若干个螺纹的牙型，对螺纹的连接强度影响不大，又缓解了螺纹的应力集中，加工方便，操作简单，同时，因螺纹牙型的减少，可加快螺纹上扣速度，也可减少错扣发生的几率。The present invention provides an internal thread joint, comprising an API round thread body, wherein the API round thread body comprises a first internal thread segment, a conical surface segment and a second internal thread segment, wherein the first internal thread segment, the conical surface segment and the second internal thread segment are arranged in sequence from the end to the bottom of the API round thread body; the structure cuts a plurality of thread profiles at positions where the force on the API round thread body is uniform and small, has little effect on the connection strength of the thread, alleviates the stress concentration of the thread, is convenient to process and simple to operate, and at the same time, due to the reduction of the thread profile, can speed up the thread threading speed and reduce the probability of wrong threading.
Description
Technical Field
The invention belongs to the technical field of threaded connection of oil casing pipes, and particularly relates to an internal threaded connector.
Background
After the conventional API threads in the oil field are engaged, the weak fatigue strength part of the internal thread is positioned at the root of the engaged thread of the first buckle close to the central plane of the coupling, as shown by the arrow in figure 1.
As can be seen from the internal thread stress distribution in fig. 2, the red color is the most stressed part (the end is not considered first because of the end effect), the yellow color is inferior to the green color, and the blue color is further inferior, so that the 1-5 buckling stresses from the end face are larger, the 6-10 buckling stresses are more average, the stress is smaller, and the 11-13 buckling stresses are larger when the internal thread is meshed. When in engagement, 1-5 buckling stress is larger from the end face, 6-10 buckling stress is average, stress is smaller, and 11-13 buckling stress is larger.
The stress concentration condition of the joint is affected by the local shape of the thread, the notch effect is generally described by the stress concentration coefficient, and under the complex underground effect, if the small end of the internal thread is cracked once the fatigue crack threshold value is reached, fatigue fracture can occur, so that huge economic loss is brought to an oil field. Therefore, the structural design of the internal thread influences the stress concentration of the joint, and further influences the production efficiency of the oil field.
Disclosure of Invention
The invention aims to provide an internal thread joint, which solves the defect that the stress concentration of the joint is large due to the existing internal thread structure, reduces the stress concentration degree of the joint through the structural design of the internal thread, improves the low cycle fatigue resistance of the joint, and realizes high-efficiency and low-cost operation.
In order to achieve the above purpose, the invention adopts the following technical scheme:
The invention provides an internal thread joint which comprises an API circular thread body, wherein the API circular thread body comprises a first internal thread section, a conical surface section and a second internal thread section, and the first internal thread section, the conical surface section and the second internal thread section are sequentially arranged from the end part to the bottom of the API circular thread body.
Preferably, the conical surface section is arranged from the eighth port to the tenth buckle from the internal thread end of the API circular thread body.
Preferably, the taper of the conical surface section is 1:16.
Preferably, the taper of the conical surface section is 1:12.
Preferably, the vertical distance between the conical surface of the conical surface section and the root conical surface of the first internal thread section is greater than or equal to zero and less than or equal to half of the thread profile height.
Preferably, the width of the conical surface section is more than or equal to 3 times of screw pitch-1 mm and less than or equal to 3 times of screw pitch +1mm.
Preferably, the conical surface section is arranged from the eighth port to the tenth buckle from the inner thread end part of the API round thread body;
The vertical distance between the conical surface of the conical surface section and the root conical surface of the first internal thread section is greater than or equal to zero and less than or equal to half of the thread profile height;
The width of the conical surface section is more than or equal to 3 times of screw pitch-1 mm and less than or equal to 3 times of screw pitch +1mm.
Preferably, the taper of the conical surface section is 1:16.
Preferably, the taper of the conical surface section is 1:12.
Compared with the prior art, the invention has the beneficial effects that:
according to the internal threaded joint, the threads of the threads are cut at the position where the stress of the API circular thread body is uniform and smaller, the influence on the connection strength of the threads is small, the stress concentration of the threads is relieved, the processing is convenient, the operation is simple, meanwhile, the thread threading speed can be increased due to the reduction of the threads, and the probability of cross threading can be reduced.
Drawings
Fig. 1 is a view showing a weak fatigue strength of an internal thread corresponding to a conventional API round thread;
FIG. 2 is a graph of internal thread stress distribution corresponding to a conventional API round thread;
FIG. 3 is a schematic view of the internal thread joint structure according to the present invention;
FIG. 4 is an enlarged view of a portion of the conical surface of the female threaded joint according to the present invention;
FIG. 5 is a plan view of the thread engagement of the internally threaded joint according to the present invention;
FIG. 6 is a female threaded joint with a thickened oil pipe of Φ88.6 to reduce the degree of stress concentration;
FIG. 7 is a location of a crack in a conventional API round thread;
FIG. 8 is a boundary load condition of a conventional API round thread;
FIG. 9 is a boundary load condition of the internally threaded joint according to the present invention;
FIG. 10 is a calculation result of a conventional API circular thread;
FIG. 11 is the maximum equivalent stress of a conventional API round thread;
fig. 12 is a calculation result of the internal thread joint according to the present invention;
FIG. 13 is the maximum equivalent stress of the internally threaded joint according to the present invention;
The thread comprises a conical surface section 1, a root conical surface section 2, an original thread tooth section 3, an API round thread body 4 and an external thread 5.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
It should be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It should also be understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
As used in the present description and the appended claims, the term "if" may be interpreted as "when..once" or "in response to a determination" or "in response to detection" depending on the context. Similarly, the phrase "if a determination" or "if a [ described condition or event ] is detected" may be interpreted in the context of meaning "upon determination" or "in response to determination" or "upon detection of a [ described condition or event ]" or "in response to detection of a [ described condition or event ]".
Furthermore, the terms "first," "second," "third," and the like in the description of the present specification and in the appended claims, are used for distinguishing between descriptions and not necessarily for indicating or implying a relative importance.
Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.
Example 1
The embodiment provides an internal thread joint, includes API circular thread body, API circular thread body includes first internal thread section, conical surface section and second internal thread section, and wherein, first internal thread section, conical surface section and second internal thread section arrange in proper order from the tip to the bottom of API circular thread body.
Example 2
On the basis of the embodiment 1, the conical surface section is arranged from the eighth port to the tenth buckle from the internal thread end of the API round thread body.
Example 3
On the basis of the embodiment 1, processing is performed on the basis of the original API round thread, 8 th to 10 th buttons are turned from the root of the internal thread to form conical surfaces, and the taper of the conical surfaces keeps the original taper of the thread, namely, the taper of the conical surface sections is 1:16 or 1:12, and the conical surfaces are shown in figures 3 and 4.
Example 4
On the basis of embodiment 1, the vertical distance between the conical surface of the conical surface section and the root conical surface of the first internal thread section is greater than or equal to zero and less than or equal to half of the thread profile height, so as to reduce the stress concentration of the whole internal thread.
Example 5
On the basis of the embodiment 1, the width of the conical surface section is 3 times of the screw pitch (P) +/-1 mm, so that the number of internal threads is reduced, the stress concentration of the whole internal threads is reduced, and the connection strength of the threads is not reduced.
The designed internal thread is meshed with the API external thread, and the graph is shown in figure 5.
Example 6
Taking a thickened oil pipe with an outer diameter of 88.9mm as an example, the thread is 8 teeth per inch, the pitch of the thread in the API is 3.175mm, wherein the distance between the conical surface section and the root conical surface of the first internal thread section is 0mm, and the width of the conical surface section is 10mm, as shown in figure 6.
Example 7
Based on example 6, the stress intensity factor of the internally threaded joint according to the present application was determined.
The method for determining the stress intensity factor mainly comprises three main categories, namely an analytic method, a numerical calculation method and a direct measurement method, wherein the analytic method is only suitable for simple problem calculation, and most problems need to be solved by the numerical method. With the rapid development of computer hardware and software, numerical calculations have become feasible. Many numerical methods have been tried to perform fracture parameter calculation such as finite difference method, boundary element method, and gridless method. However, these numerical methods are relatively lacking in industrial application examples due to the lack of support of commercial software. In the past half a century, the finite element method is efficient and low in cost and is successfully applied to many industrial departments. There are many powerful software available now, the present application uses finite element software to calculate, compared with the threads of the same specification of API, the same crack is present at the same location, the crack length is 5mm, the crack tip area is the circular area of 0.5mm in the figure, and the expansion direction is toward the two ends of the crack, as shown in fig. 7.
When the two boundary conditions are the same, the center of the coupling is fixedly restrained in the X direction, the outer diameter of the coupling is fixedly restrained in the Y direction, and the end part bears 100MPa of tensile load, as shown in fig. 8 and 9.
The model adopts a traditional girth integration algorithm in finite elements, a crack tip adopts CPS6 (six-node secondary plane stress triangle unit), the rest part adopts CPS8 (eight-node bidirectional secondary plane stress quadrilateral unit) for calculation, and the result is shown in figures 10-13:
The crack is perpendicular to the tensile stress, belongs to type I cracks (open type), is also the most dangerous and common crack, and is compared with the maximum equivalent stress and stress intensity factor (calculated by adopting a four-lane) to obtain the following table:
table 1 comparison of API thread with an internal thread Joint calculation
From table 1, it can be seen that the internal thread joint has reduced stress intensity factor, J integral (J integral is generally used to describe the degree of crack top stress-strain field singularity of elastoplastic plane crack body) and maximum equivalent stress, especially reduced by 20% compared with API thread, and the structure improves the capability of preventing fatigue accidents at low cycle of the joint, and realizes high-efficiency and low-cost operation.
The structure cuts the tooth shapes of 3 threads at the position where the internal thread is uniformly stressed and smaller, has little influence on the connection strength of the threads, relieves the stress concentration of the threads, is convenient to process and simple to operate, can accelerate the thread screwing speed due to the reduction of the tooth shapes of the threads, and can reduce the probability of cross buckling.
The foregoing embodiments are merely illustrative of the technical solutions of the present application, and not restrictive, and although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that modifications may still be made to the technical solutions described in the foregoing embodiments or equivalent substitutions of some technical features thereof, and that such modifications or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims (9)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311295584.5A CN119777747A (en) | 2023-10-08 | 2023-10-08 | Internal thread connector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311295584.5A CN119777747A (en) | 2023-10-08 | 2023-10-08 | Internal thread connector |
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| Publication Number | Publication Date |
|---|---|
| CN119777747A true CN119777747A (en) | 2025-04-08 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311295584.5A Pending CN119777747A (en) | 2023-10-08 | 2023-10-08 | Internal thread connector |
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| CN (1) | CN119777747A (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101627248A (en) * | 2006-01-26 | 2010-01-13 | B·W·拉莫斯 | threaded pipe connection |
| CN201496003U (en) * | 2009-08-27 | 2010-06-02 | 江苏胜大石油设备制造有限公司 | Thread connector of special oil sleeve |
| CN202745719U (en) * | 2012-07-26 | 2013-02-20 | 中国石油天然气股份有限公司 | Drill tool nipples with extensions |
| CN202832261U (en) * | 2012-07-31 | 2013-03-27 | 中国石油天然气集团公司 | Petroleum casing joint |
| CN203531767U (en) * | 2013-08-29 | 2014-04-09 | 杨林 | Eight-tooth cylinder threaded connector |
| CN207004443U (en) * | 2017-06-05 | 2018-02-13 | 中国海洋石油总公司 | A kind of nipple |
| FR3098878A1 (en) * | 2019-07-19 | 2021-01-22 | Vallourec Oil And Gas France | Threaded joint for oil well casing column |
| CN114402117A (en) * | 2019-07-19 | 2022-04-26 | 瓦卢瑞克石油天然气法国有限公司 | Threaded connection with asymmetrical helical profile |
-
2023
- 2023-10-08 CN CN202311295584.5A patent/CN119777747A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101627248A (en) * | 2006-01-26 | 2010-01-13 | B·W·拉莫斯 | threaded pipe connection |
| CN201496003U (en) * | 2009-08-27 | 2010-06-02 | 江苏胜大石油设备制造有限公司 | Thread connector of special oil sleeve |
| CN202745719U (en) * | 2012-07-26 | 2013-02-20 | 中国石油天然气股份有限公司 | Drill tool nipples with extensions |
| CN202832261U (en) * | 2012-07-31 | 2013-03-27 | 中国石油天然气集团公司 | Petroleum casing joint |
| CN203531767U (en) * | 2013-08-29 | 2014-04-09 | 杨林 | Eight-tooth cylinder threaded connector |
| CN207004443U (en) * | 2017-06-05 | 2018-02-13 | 中国海洋石油总公司 | A kind of nipple |
| FR3098878A1 (en) * | 2019-07-19 | 2021-01-22 | Vallourec Oil And Gas France | Threaded joint for oil well casing column |
| CN114402117A (en) * | 2019-07-19 | 2022-04-26 | 瓦卢瑞克石油天然气法国有限公司 | Threaded connection with asymmetrical helical profile |
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