阅读说明：本技术 一种防腐承扩口钢管及制作方法 (Anti-corrosion flaring-bearing steel pipe and manufacturing method thereof ) 是由 张翼飞 张德森 于 2020-04-24 设计创作，主要内容包括：本发明是一种防腐承扩口钢管及制作方法,围绕钢管产品的不同结构特点,对现有承扩口连接管道制造工艺的不足进行优化,结合不同规格尺寸、材质管材的质量要求,通过对不同数据的整合,提高在数字化控制下的防腐承扩口钢管制作的可靠性及精确性,使得钢管承口和扩口的定型尺寸更加符合设计要求,本发明可满足直径100毫米至3600毫米之间、压力等级在2.0MPa以上管网工程的质量要求。(The invention relates to an anti-corrosion flaring bearing steel pipe and a manufacturing method thereof, which are characterized by surrounding different structural characteristics of steel pipe products, optimize the defects of the existing flaring bearing connecting pipeline manufacturing process, combine the quality requirements of pipes with different specifications and sizes and materials, and improve the reliability and the accuracy of the anti-corrosion flaring bearing steel pipe manufacturing under digital control by integrating different data, so that the sizing sizes of a steel pipe bell mouth and a flaring mouth are more in line with the design requirements, and the invention can meet the quality requirements of pipe network engineering with the diameter of 100 mm to 3600 mm and the pressure grade of more than 2.0 MPa.)

1. An anti-corrosion bell-mouth-bearing steel pipe is characterized by comprising a pipe body part, a bell mouth part, a flared part and an inner and outer anti-corrosion layer,

further, the structure of the bell-mouthed steel pipe is any one of a seamless steel pipe, a high-frequency straight welded pipe and a spiral welded steel pipe;

further, the pipe body part is any one of bodies of a seamless steel pipe, a high-frequency straight welded pipe and a spiral welded steel pipe;

furthermore, one end of the socket part is provided with a flanging which forms a certain angle with the smooth curved surface of the outer wall of the socket part in the centripetal direction, the other end of the socket part is provided with a cone-shaped area with gradually changed diameter and forms a certain angle with the outer wall of the pipe body part, two alternate annular grooves which provide mounting space for the rubber sealing ring are arranged between the flanging of the outer wall and the cone-shaped area and in the smooth curved surface of the outer wall, and two annular ribs which are raised alternately are arranged in the inner wall of the socket part, and the inner diameter of the annular ribs is the same as the inner diameter of the pipe body part;

furthermore, one end of the flaring part is provided with a flanging which forms a certain angle with the smooth curved surface of the flaring part in the radial direction, the other end of the flaring part is provided with a conical barrel area with gradually changed diameter and forms a certain angle with the outer wall of the pipe body part, and a curved surface which is smooth by the inner wall and the outer wall is arranged between the flanging in the radial direction and the conical barrel area;

furthermore, the inner anti-corrosion layer is provided with a bonding agent with a certain thickness and an epoxy powder (any one of PE, PP and EP powder) composite layer;

further, the outer anticorrosive layer is a 3PE anticorrosive layer or/and a hot compress PE layer;

furthermore, the anti-corrosion bell-mouth steel pipe is tightly sleeved and connected with the bell-mouth part through a sealing rubber ring in a groove of the bell-mouth part;

further, the outer diameter and the height of the smooth curved surface in the socket part are smaller than the inner diameter and the height of the smooth curved surface of the inner wall in the flaring part.

2. An erosion resistant bell mouth steel tube as claimed in claim 1 wherein the height of the smooth curved surface in the bell mouth is in the range 40 mm to 350 mm.

3. The corrosion resistant bell mouth steel pipe of claim 1 wherein the height of the smooth curved surface of the inner wall in the mouth portion is in the range of 60 mm to 460 mm.

4. The corrosion-resistant bell-mouthed steel pipe according to claim 1, characterized in that the number of grooves of said bell portion is one to three.

5. An anticorrosion bell mouth steel pipe according to claim 1, wherein the groove center distance of the bell mouth is in the range of 20 mm to 100 mm.

6. An anticorrosion bell mouth steel pipe according to claim 1, wherein the groove width of the bell mouth is in the range of 8 mm to 70 mm.

7. An erosion resistant bell mouth steel tube as claimed in claim 1 wherein the depth of the groove in the bell mouth is in the range 4 mm to 40 mm.

8. The corrosion-resistant bell-mouthed steel pipe according to claim 1, characterized in that the flanging angle and the angle of the conical cylinder area of the bell-mouthed part should be greater than 120 degrees.

9. A method for manufacturing an anti-corrosion flaring-bearing steel pipe comprises the following steps:

the special equipment required by the anti-corrosion flaring bearing steel pipe comprises steel pipe bell mouth manufacturing equipment, steel pipe flaring manufacturing equipment and a special steel pipe bracket, wherein the steel pipe bell mouth and the flaring equipment are respectively arranged at two ends of the special steel pipe bracket and are on the same axial line, and two ends of the special steel pipe bracket are respectively provided with a medium-frequency heating ring capable of sliding and moving;

firstly, placing a steel pipe to be manufactured with a flaring bearing into a special bracket for the steel pipe, slidably sleeving an intermediate frequency heating ring at two end parts of the steel pipe, starting a heating function of the intermediate frequency heating ring, and heating the two end parts of the steel pipe;

secondly, when the two end parts of the steel pipe are heated to the temperature design values for manufacturing the bell mouth part and the flared part of the steel pipe, an electric control signal is fed back, the heating function of the medium-frequency heating ring is stopped, and the forward and backward movement functions in the bell mouth and the flared part manufacturing equipment are synchronously started;

thirdly, when the inner templates in the bellmouth and flaring manufacturing equipment respectively move to the design values in the heating area cavities at the two ends of the steel pipe, the electric control signal is fed back, the forward and backward movement functions in the bellmouth and flaring manufacturing equipment are synchronously stopped, the operation function of the inner templates in the equipment is started, and the bell mouth and flaring manufacturing of the steel pipe is started;

fourthly, when the radial motion of the inner templates in the bellmouth and flaring equipment reaches a design value, feeding back an electric control signal, stopping the radial motion of the inner templates at the same time, starting the centripetal motion at the same time, and synchronously starting the circumferential rotation angle function of the inner templates in the equipment or/and using the circumferential rotation angle of the steel pipe;

fifthly, when design values of the centripetal movement, the circumferential rotation angle movement or/and the steel pipe circumferential rotation angle movement of the inner template are reached, the electric control signal feedback, the centripetal movement of the inner template, the circumferential rotation angle movement or/and the steel pipe circumferential rotation angle movement are synchronously stopped, the radial movement of the inner template is started, and flaring manufacturing is carried out on the unmachined areas of the bell mouth part and the flared part of the steel pipe;

sixthly, feeding back an electric control signal and synchronously starting the heating function of the intermediate frequency heating ring when the roundness design values of the inner walls of the bell mouth part and the flared part of the steel pipe are reached through multiple actions of the fourth step and the fifth step, stopping the heating function of the intermediate frequency heating ring when the design values of the manufacturing temperature of the bell mouth part and the flared part of the steel pipe are reached, feeding back the electric control signal, and starting an inner template and an outer template in equipment in sequence;

seventhly, when the inner template reaches a radial movement design value, the electric control signal feedback is stopped, when the outer template reaches a centripetal movement design value, the steel pipe socket part and the flared part are sufficiently pressed and shaped in the space designed by the inner template and the outer template in the equipment, at the moment, the electric control signal feedback is carried out, the inner template is started by centripetal movement, the outer template is started by radial movement, and the function of the circumferential rotation angle of the inner template and the outer template is started or/and the function of the circumferential rotation angle of the steel pipe is started;

eighthly, when the centripetal motion of the inner template, the radial motion of the outer template and the circumferential rotation angle reach design values, the functions of electric control signal feedback and circumferential rotation angle are stopped, the inner template performs radial motion, the outer template performs centripetal motion and is started in sequence, and the seventh step is repeated;

ninth, finishing shaping and manufacturing the bell mouth part and the flared part of the steel pipe by multiple actions of the seventh step and the eighth step, starting a back-and-forth movement function in bell mouth and flared part manufacturing equipment, enabling the inner die to respectively withdraw from the bell mouth part and the flared part cavity and stop, starting a middle-frequency heating ring sliding function and a middle-frequency heating ring sliding function in a special bracket for the steel pipe, enabling the middle-frequency heating ring to withdraw from the bell mouth part and the flared part and stop, transferring the bell mouth-bearing steel pipe to the next steel pipe bracket, and performing an anti-corrosion process manufacturing;

tenth step, the anti-corrosion process of the bell-end steel pipe is basically the same as the 3PE steel pipe, except that: the inner wall and the outer wall of the anti-corrosion flaring bearing steel pipe are anti-corrosion by adopting a turnover steel pipe bracket.

10. The method for manufacturing the anti-corrosion bell-mouthed steel pipe according to claim 9, wherein the functions of the circumferential rotation angles of the inner and outer templates are the same.

Technical Field

The invention relates to the technical field of structural design of pressure-bearing steel pipe connection, in particular to an anti-corrosion flaring-bearing steel pipe and a manufacturing method thereof.

Background

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a novel anti-corrosion bell-shaped steel pipe and a manufacturing method thereof, which are used for improving the process requirement of manufacturing the bell-shaped steel pipe, thereby ensuring the technical requirement on product connection in engineering application and further improving the social benefit and the economic benefit of enterprises.

The technical scheme adopted by the invention for solving the technical problems is as follows:

an anti-corrosion bell-mouth-bearing steel pipe is characterized by comprising a pipe body part, a bell mouth part, a flared part and an inner and outer anti-corrosion layer.

Further, the structure of the bell-mouthed steel pipe is any one of a seamless steel pipe, a high-frequency straight welded pipe and a spiral welded steel pipe structure.

Further, the pipe body part is any one of bodies of a seamless steel pipe, a high-frequency straight welded pipe and a spiral welded steel pipe.

Furthermore, one end of the socket part is provided with a flanging which forms a certain angle with the smooth curved surface of the outer wall of the socket part in the centripetal direction, the other end of the socket part is provided with a cone-shaped cylinder area with gradually changed diameter and forms a certain angle with the outer wall of the pipe body part, two alternate annular grooves which provide installation space for the rubber sealing rings are arranged between the flanging of the outer wall and the cone-shaped cylinder area and in the smooth curved surface of the outer wall, and the inner wall of the socket part is provided with two annular ribs which are protruded alternately and have the same inner diameter as the inner diameter of the pipe body part.

Furthermore, one end of the flaring portion is provided with a flanging which forms a certain angle with the smooth curved surface of the flaring portion in the radial direction, the other end of the flaring portion is provided with a conical barrel area with gradually changed diameter and forms a certain angle with the outer wall of the pipe body portion, and a curved surface which is smooth by the inner wall and the outer wall is arranged between the flanging in the radial direction and the conical barrel area.

Furthermore, the inner anti-corrosion layer is provided with a bonding agent with a certain thickness and an epoxy powder (any one of PE, PP and EP powder) composite layer.

Further, the outer anticorrosive layer is a 3PE anticorrosive layer or/and a hot compress PE layer.

Furthermore, the anti-corrosion flaring steel pipe is tightly sleeved and connected with the flaring part through a sealing rubber ring in a groove of the flaring part.

Further, the outer diameter and the height of the smooth curved surface in the socket part are smaller than the inner diameter and the height of the smooth curved surface of the inner wall in the flaring part.

The height of the smooth curved surface in the socket portion is in the range of 40 mm to 350 mm.

The height of the smooth curved surface of the inner wall in the flaring portion is in the range of 60 mm to 460 mm.

The number of the grooves of the socket part is one to three.

The distance between the centers of the grooves of the socket part is in the range of 20 mm to 100 mm.

The groove width of the socket portion is in the range of 8 mm to 70 mm.

The socket portion has a groove depth in the range of 4 mm to 40 mm.

The flanging angle and the angle of the conical cylinder area of the bearing and flaring part are larger than 120 degrees.

A method for manufacturing an anti-corrosion flaring-bearing steel pipe comprises the following steps:

the special equipment required by the anti-corrosion flaring bearing steel pipe comprises steel pipe bell mouth manufacturing equipment, steel pipe flaring manufacturing equipment and a special steel pipe bracket, wherein the steel pipe bell mouth and the flaring equipment are respectively arranged at two ends of the special steel pipe bracket and are on the same axial line, and the two ends of the special steel pipe bracket are respectively provided with a medium-frequency heating ring capable of sliding.

Firstly, a steel pipe to be manufactured with a flaring is placed in a special bracket for the steel pipe, an intermediate frequency heating ring is sleeved at two end parts of the steel pipe in a sliding manner, and the heating function of the intermediate frequency heating ring is started to heat the two end parts of the steel pipe.

And secondly, when the two end parts of the steel pipe are heated to the temperature design values for manufacturing the bell mouth part and the flared part of the steel pipe, the electric control signal is fed back, the heating function of the intermediate frequency heating ring is stopped, and the forward and backward movement functions in the bell mouth and the flared part manufacturing equipment are synchronously started.

And thirdly, when the inner templates in the bellmouth and flaring manufacturing equipment respectively move to the design values in the heating area cavities at the two ends of the steel pipe, feeding back an electric control signal, synchronously stopping the forward and backward movement functions in the bellmouth and flaring manufacturing equipment, starting the operation function of the inner templates in the equipment, and starting the manufacturing of the bell mouth and the flaring of the steel pipe.

And fourthly, when the radial motion of the inner templates in the bellmouth and flaring equipment reaches a design value, feeding back an electric control signal, stopping the radial motion of the inner templates at the same time, starting the centripetal motion at the same time, and synchronously starting the circumferential rotation angle function of the inner templates in the equipment or/and using the circumferential rotation angle of the steel pipe.

And fifthly, when the design values of the centripetal movement, the circumferential rotation angle movement or/and the steel pipe circumferential rotation angle movement of the inner template are reached, the electric control signal feedback, the centripetal movement of the inner template, the circumferential rotation angle movement or/and the steel pipe circumferential rotation angle movement are synchronously stopped, the radial movement of the inner template is started, and the flaring manufacture is carried out on the steel pipe bell mouth part and the flaring part unprocessed area.

And sixthly, feeding back an electric control signal and synchronously starting the heating function of the intermediate frequency heating ring when the roundness design values of the inner walls of the bell mouth part and the flared part of the steel pipe are reached through multiple actions of the fourth step and the fifth step, stopping the heating function of the intermediate frequency heating ring when the design values of the manufacturing temperature of the bell mouth part and the flared part of the steel pipe are reached, feeding back the electric control signal, and starting the inner template and the outer template in the equipment in sequence.

And seventhly, stopping electric control signal feedback when the inner template reaches a radial movement design value, fully pressing and shaping the steel pipe socket part and the flared part in the space designed by the inner template and the outer template in the equipment when the outer template reaches a centripetal movement design value, feeding back the electric control signal, starting the inner template in a centripetal movement mode, starting the outer template in a radial movement mode, starting the circumferential rotation angle function of the inner template and the outer template or/and starting the circumferential rotation angle function of the steel pipe.

And step eight, when the centripetal motion of the inner template, the radial motion of the outer template and the circumferential rotation angle reach design values, the functions of electric control signal feedback and circumferential rotation angle are stopped, the inner template performs radial motion, the outer template performs centripetal motion and is started in sequence, and the seventh step is repeated.

And ninthly, finishing shaping and manufacturing the bell mouth part and the flared part of the steel pipe through multiple actions of the seventh step and the eighth step, starting a back-and-forth movement function in bell mouth and flared part manufacturing equipment, enabling the inner die to respectively withdraw from the bell mouth part and the flared part cavity and stop, starting a middle-frequency heating ring sliding function and a middle-frequency heating ring sliding function in the special bracket for the steel pipe, enabling the middle-frequency heating ring to withdraw from the bell mouth part and the flared part and stop, and transferring the bell mouth-bearing steel pipe to the next steel pipe bracket to perform anticorrosion process manufacturing.

Tenth step, the anti-corrosion process of the bell-end steel pipe is basically the same as the 3PE steel pipe, except that: the inner wall and the outer wall of the anti-corrosion flaring bearing steel pipe are anti-corrosion by adopting a turnover steel pipe bracket.

The function of the circumferential rotation angle of the inner template and the outer template is the same function.

The invention has the beneficial effects that:

the invention relates to an anti-corrosion flaring bearing steel pipe and a manufacturing method thereof, which are characterized by surrounding different structural characteristics of steel pipe products, optimize the defects of the existing flaring bearing connecting pipeline manufacturing process, combine the quality requirements of pipes with different specifications and sizes and materials, and improve the reliability and the accuracy of the anti-corrosion flaring bearing steel pipe manufacturing under digital control by integrating different data, so that the sizing sizes of a steel pipe bell mouth and a flaring mouth are more in line with the design requirements, and the invention can meet the quality requirements of pipe network engineering with the diameter of 100 mm to 3600 mm and the pressure grade of more than 2.0 MPa.

The technical advantages of the invention are further explained below by combining with a specific embodiment of the manufacture of the anti-corrosion flaring-bearing seamless steel pipe.

Drawings

Fig. 1 is a perspective view of an anti-corrosion bell-mouth steel pipe.

Fig. 2 is a cross-sectional view of fig. 1A-a.

Fig. 3 is a schematic perspective view of the connection of the anti-corrosion flaring bearing steel pipe.

Fig. 4 is a cross-sectional view of fig. 3A-a.

Fig. 5 is a front perspective view of a steel pipe socket manufacturing apparatus.

Fig. 6 is a front perspective view of the steel pipe flaring manufacturing apparatus.

Fig. 7 is a perspective view of a production line of special manufacturing equipment for bell mouth steel pipes.

Fig. 8 is a flow chart of the process for manufacturing the anti-corrosion flaring-bearing steel pipe.

Detailed Description

An anti-corrosion flaring steel pipe is characterized by comprising a pipe body part 1, a bell mouth part 2, a flaring part 3, an inner anti-corrosion layer 4, an outer anti-corrosion layer 5 and a sealing rubber ring 6, and referring to figures 1 and 2.

One end of the socket part 2 is provided with a centripetal flange 21, the other end is provided with a cone area 22, two alternate annular grooves 231 and 232 are arranged in a smooth curved surface 23 of the outer wall between the flange 21 and the cone area 22, two protruding alternate annular ribs 241 and 242 are arranged in the inner wall 24, and the inner diameter of the two protruding alternate annular ribs is the same as the inner diameter of the pipe body part 1, refer to fig. 2.

One end of the flared part 3 is provided with a flange 32 which forms an angle with the smooth curved surface 31 of the inner wall of the flared part 3 in the radial direction, and the other end is provided with a conical cylinder area 33 which forms a certain angle with the pipe body part 1, refer to fig. 2.

The outer diameter and length of the smooth curved surface 23 of the outer wall in the socket portion 2 are smaller than the inner diameter and length of the smooth curved surface 31 of the inner wall in the flare portion 3, refer to fig. 2.

The connection of the anticorrosion bell-mouth steel pipe is that the sealing rubber ring 6 is put into the annular grooves 231 and 232 in the bell-mouth part 2 and is tightly sleeved and connected with the smooth curved surface 31 of the inner wall in the bell-mouth part 3, refer to fig. 3 and 4.

A method for manufacturing an anti-corrosion flaring-bearing steel pipe comprises the following steps:

the special equipment required by the anti-corrosion flaring-bearing steel pipe manufacturing comprises steel pipe bell mouth manufacturing equipment 10, steel pipe flaring manufacturing equipment 20 and a special steel pipe bracket 30, wherein the steel pipe bell mouth equipment 10 and the steel pipe flaring equipment 20 are respectively arranged at two ends of the special steel pipe bracket 30 and are on the same axial line, and intermediate- frequency heating rings 301 and 302 which can slide and move are respectively arranged at two ends of the special steel pipe bracket 30, and refer to fig. 5, 6 and 7.

First, the steel pipe 40 to be formed with the bell mouth is placed in the steel pipe bracket 30, the intermediate frequency heating rings 301 and 302 are slidably fitted over both ends of the steel pipe 40, and the heating function of the intermediate frequency heating rings 301 and 302 is activated to heat both ends of the steel pipe 40, referring to fig. 7.

Secondly, when the two ends of the steel pipe 40 are heated to the designed temperature values for manufacturing the socket part 2 and the flare part 3, the electric control signal is fed back, the heating function in the intermediate frequency heating rings 301 and 302 is stopped, and the back-and-forth movement function in the socket manufacturing device 10 and the flare manufacturing device 20 is started synchronously, referring to fig. 7.

Thirdly, when the inner die plate 101 in the bellmouth making device 10 and the inner die plate 201 in the flare making device 20 respectively move to the design values in the heating area cavities at the two ends of the steel pipe 40, the electric control signal feedback, the back-and-forth movement function in the bellmouth making device 10 and the flare making device 20 are simultaneously stopped, the radial movement function of the inner die plates 101 and 201 is started, and the making of the bellmouth part 2 and the bellmouth part 3 of the steel pipe 40 is started, referring to fig. 5, 6 and 7.

Fourthly, when the radial movement of the inner templates 101 and 201 reaches the design value, the electric control signal is fed back, the radial movement of the inner templates 101 and 201 is stopped simultaneously, the centripetal movement is started simultaneously, and the circumferential rotation angle functions of the inner templates 101 and 201 in the socket manufacturing device 10 and the flaring manufacturing device 20 are started simultaneously or/and the circumferential rotation angle of the steel pipe 40 is/are started simultaneously, referring to fig. 5, 6 and 7.

Fifthly, when the inner die plates 101 and 201 move centripetally and rotate circumferentially or/and the steel pipe 40 rotates circumferentially to reach a design value, an electric control signal is fed back, the inner die plates 101 and 201 move centripetally and rotate circumferentially or/and the steel pipe 40 rotates circumferentially to stop, the inner die plates 101 and 201 start radial movement, and flaring manufacturing is carried out on unprocessed areas in the bell mouth part 2 and the flared part 3 of the steel pipe 40, and reference is made to fig. 5, fig. 6 and fig. 7.

Sixthly, through multiple actions of the fourth step and the fifth step, when the roundness design values of the inner walls of the bell mouth part 2 and the flared part 3 of the steel pipe 40 are reached, the electric control signal is fed back, the heating functions of the intermediate frequency heating rings 301 and 302 are started simultaneously, when the roundness design values of the inner walls of the bell mouth part 2 and the flared part 3 of the steel pipe 40 are reached, the heating functions of the intermediate frequency heating rings 301 and 302 are stopped, the inner templates 101 and 201 and the outer templates 102 and 202 in the bell mouth manufacturing device 10 and the flared mouth manufacturing device 20 are started sequentially through the electric control signal feedback, and reference is made to fig. 5, fig..

Seventhly, when the inner formworks 101 and 201 reach the radial movement design value, the electric control signal feedback is stopped, when the outer formworks 102 and 202 reach the centripetal movement design value, the bell mouth parts 2 and the flared parts 3 in the steel pipe 40 and the spaces designed by the inner formworks 101 and 201 and the outer formworks 102 and 202 are sufficiently pressed and shaped, and at the moment, the electric control signal feedback, the centripetal movement starting of the inner formworks 101 and 201, the radial movement starting of the outer formworks 102 and 202, the starting of the circumferential rotation angle functions of the inner formworks 101 and 201 and the outer formworks 102 and 202 or/and the synchronous starting of the circumferential rotation angle functions of the steel pipe 40 are carried out, and reference is made to fig. 5, fig. 6 and fig.

And eighthly, when the inner formworks 101 and 201 move centripetally, the outer formworks 102 and 202 move radially, and the circumferential rotation angle reaches the design value, feeding back an electric control signal, stopping the function of the circumferential rotation angle, starting the inner formworks 101 and 201 by radial movement, starting the outer formworks 102 and 202 by centripetal movement, and repeating the seventh step, wherein reference is made to fig. 5, 6 and 7.

Ninth, finishing the shaping and manufacturing of the bell mouth part 2 and the flared part 3 in the steel pipe 40 by multiple actions of the seventh step and the eighth step, starting the forward and backward movement function in the bell mouth and flared part manufacturing devices 10 and 20, enabling the inner formworks 101 and 201 to exit from the cavity in the bell mouth part 2 and the flared part 3 in the steel pipe 40, starting the sliding function of the medium-frequency heating ring 301 and the medium-frequency heating ring 302 in the special steel pipe bracket 30, enabling the medium-frequency heating ring 301 and the medium-frequency heating ring 302 to exit from the bell mouth part 2 and the flared part 3 respectively, transferring the steel pipe bearing flared part to the next steel pipe bracket, and performing the manufacturing of the anticorrosion process, referring to fig. 5, fig. 6 and.

Tenth step, the anticorrosion process of the bell-end steel pipe is basically the same as that of the 3PE steel pipe, and the difference is that: the anti-corrosion flaring bearing steel pipe uses the overturning bracket when the inner and outer anti-corrosion layers are manufactured, and the rest is the same, and refer to fig. 8.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements by those skilled in the art may be made without departing from the spirit of the present invention, which is defined by the claims.