阅读说明：本技术 一种管接头与管道的连接方法 (Method for connecting pipe joint and pipeline ) 是由 朱旭林 于 2021-01-07 设计创作，主要内容包括：本发明提供一种管接头与管道的连接方法,所述管接头用于至少跟一根金属管道相连,所述管接头包括一体化设置的金属主体,所述金属主体在轴向里端至外端依次包括内接段、硬密封缩紧段和非缩紧段,所述金属管道用于从管接头的金属主体外端至里端的方向插入所述管接头中,之后借助工具施加径向缩紧力使得所述管接头的缩紧段在径向方向由外而内收缩和锁紧在所述金属管道的外壁上。本发明中首次采用软硬密封结合的方式,其中硬密封属于金属与金属之间的铆合工艺,杜绝塑料填充,解决塑料或橡胶密封圈老化从而带来漏水隐患的问题；其中软密封能进一步保障产品的密封稳定性,从而保障用水的安全；而且该软密封的使用还能相应节约接头安装用工数量。(The invention provides a pipe joint and a method for connecting a pipe, wherein the pipe joint is used for being connected with at least one metal pipe, the pipe joint comprises an integrally arranged metal main body, the metal main body sequentially comprises an internal connection section, a hard seal shrinkage section and a non-shrinkage section from the inner end to the outer end in the axial direction, the metal pipe is used for being inserted into the pipe joint from the outer end to the inner end of the metal main body of the pipe joint, and then a radial shrinkage force is applied by means of a tool to enable the shrinkage section of the pipe joint to be shrunk and locked on the outer wall of the metal pipe from outside to inside in the radial direction. In the invention, a soft and hard seal combination mode is adopted for the first time, wherein hard seal belongs to a riveting process between metal and metal, plastic filling is avoided, and the problem of hidden water leakage caused by aging of a plastic or rubber sealing ring is solved; the soft sealing can further guarantee the sealing stability of the product, thereby guaranteeing the safety of water consumption; and the soft seal can correspondingly save the labor amount for installing the joint.)

1. A pipe joint and a connecting method of a pipeline, the pipe joint is used for being connected with at least one metal pipeline, the pipe joint comprises an integrally arranged metal main body, the metal main body sequentially comprises an internal connection section (1), a hard seal shrinkage section (2) and a non-shrinkage section (3) from the inner end to the outer end in the axial direction, the metal pipeline is used for being inserted into the pipe joint from the outer end to the inner end of the metal main body of the pipe joint, and then radial shrinkage force is applied by means of a tool to enable the shrinkage section of the pipe joint to be shrunk and locked on the outer wall of the metal pipeline from outside to inside in the radial direction; the inner connecting section (1) comprises an inner connecting part (11) with a cylindrical outer wall and a pipe end blocking step (12) for blocking the axial end part of the metal pipeline, the hard sealing and tightening section (2) comprises a hard sealing and tightening part (21) with a cylindrical outer wall and a first convex ring (22), the first convex ring (22) is arranged on the inner wall of the hard sealing and tightening section (2) and protrudes annularly from the inner wall of the hard sealing and tightening section (2) to the radial inner side of the hard sealing and tightening section, the non-tightening section (3) comprises a non-tightening part (31) with a cylindrical outer wall and an annular groove (32), the annular groove (32) is arranged on the inner wall of the non-tightening section (3) and is recessed annularly from the inner wall of the non-tightening section (3) to the radial outer side of the non-tightening section, and the annular groove (32) is used for accommodating a sealing ring (5); after a radial reducing force is applied to the pipe joint by means of a tool, the convex ring is used for radially and inwards pressing the convex ring on the outer wall of the metal pipeline to form a first defense line for connecting and sealing the pipe joint and the metal pipeline, and the sealing ring is used for forming a second defense line for connecting and sealing the pipe joint and the metal pipeline.

2. The method according to claim 1, characterized in that the metal body further comprises a second collar (23), the second collar (23) is also provided on the inner wall of the hard seal reduction section (2) and projects annularly from the inner wall of the hard seal reduction section (2) to the radially inner side thereof, and the first collar (22) and the second collar (23) are arranged back and forth in the axial direction of the pipe joint, and the first collar (22) is located near the inner end of the metal body and the second collar (23) is located near the outer end of the metal body.

3. A method according to claim 1, wherein the metal body further comprises an end tightening section (4) arranged at an axially outer end of the non-tightening section (3), the end tightening section (4) comprising an end tightening portion (41) providing a direct contact location for applying a radial tightening force to the tool; in the connecting method, the tool wraps the hard sealing tightening part (21) and the end tightening part (41) respectively, the tool provides radial tightening force for the hard sealing tightening section (2) and the end tightening section (4) simultaneously, and the outer diameter of the end tightening section (4) is smaller than or equal to that of the inner connecting section (1); the end part tightening section (4) forms a plurality of circumferentially dispersed end part tightening points (42) after the tool is applied with force and tightened.

4. Method according to claim 1, wherein the pipe joint comprises a metal body and a sealing ring (5) arranged in the annular groove, preferably the sealing ring is a rubber O-ring.

5. A method according to any one of claims 1 to 4, characterised in that the external diameters of the inscribing section (1), the hard seal constricting section (2) and the non-constricting section (3) increase in sequence.

6. The method according to any one of claims 1 to 4, wherein the pipe joint is an elbow joint for connecting two metal pipes, the elbow joint comprises an integrally arranged metal body, the metal body comprises two groups of axial bodies, each group of axial bodies sequentially comprises an inner connecting section (1), a hard seal shrinkage section (2) and a non-shrinkage section (3) from the axial inner end to the axial outer end of the axial body, and the elbow body is integrally arranged between the two inner connecting sections (1) so that the axial lines of the two groups of axial bodies form an included angle of 10-170 degrees; preferably, the metal elbow joint is L-shaped as a whole, namely, an included angle of 90 degrees is formed between the axial leads of the two groups of axial main bodies.

7. The method according to any one of claims 1 to 4, wherein the pipe joint is an internal thread joint, the internal thread joint is used for connecting a metal pipeline and a water faucet, the internal thread joint comprises an integrally arranged metal body, the integrally arranged internal thread body is further included in the metal body, the internal thread body is coaxially arranged with the inner connecting section (1) and the hard sealing and shrinking section (2), the internal thread body is arranged at one end of the inner connecting section (1) opposite to the hard sealing and shrinking section (2), and internal threads are arranged on the internal thread body and used for connecting the internal thread joint and the water faucet.

8. The method according to any one of claims 1 to 4, wherein the pipe joint is an outer screw joint, the outer screw joint is used for connecting a metal pipeline and a water faucet, the outer screw joint comprises an integrally arranged metal body, the integrally arranged outer screw body is further included in the metal body, the outer screw body is coaxially arranged with the inner connecting section (1) and the hard seal shrinkage section (2), the outer screw body is arranged at one end of the inner connecting section (1) opposite to the hard seal shrinkage section (2), and external threads are arranged on the outer screw body and used for connecting the outer screw joint and the water faucet.

9. The method according to any one of claims 1 to 4, characterized in that the pipe joint is a metal tee joint for connecting three metal pipes, the tee joint comprises an integrally arranged metal body, the metal body comprises three groups of axial bodies, each group of axial bodies sequentially comprises an inner connecting section (1), a hard sealing shrinkage section (2) and a non-shrinkage section (3) from the axial inner end to the axial outer end of the axial body, and the tee joint bodies are integrally arranged among the three inner connecting sections (1), so that the axial leads of the three groups of axial bodies form an included angle of 10 to 170 degrees in pairs; preferably, the metal three-way joint is integrally T-shaped, namely, two groups of axial main bodies are linearly arranged at an angle of 180 degrees between the axial leads of the two groups of axial main bodies, and the axial leads of the two groups of axial main bodies form an included angle of 90 degrees with the axial lead of the other group of axial main bodies.

10. The method according to any one of claims 1 to 4, wherein the pipe joint is a metal straight joint for connecting two metal pipes, the straight joint comprises an integrally arranged metal body, the metal body comprises two groups of axial bodies, each group of axial bodies sequentially comprises an inner connecting section (1), a hard sealing shrinking section (2) and a non-shrinking section (3) from the axial inner end to the axial outer end of the axial body, and the straight body is integrally arranged between the two inner connecting sections (1) or the two inner connecting sections (1) are directly and coaxially butted, so that the axial lines of the two groups of axial bodies form 180 degrees.

Technical Field

The invention belongs to the field of pipeline connecting pieces, and particularly relates to a pipeline joint for connecting metal pipelines and a connecting method thereof.

Background

The existing metal fittings for connecting metal water pipes generally comprise two generations of products. In the first generation of joint products, the sealing structure for preventing water leakage is a rubber sealing ring, and belongs to a soft sealing structure. The sealing ring in the product is easy to age and damage, and easily releases toxin at high temperature, thus being not environment-friendly. The connection mode of the second generation joint product and the metal water pipe is clamping and pressing type, compaction and sealing, and belongs to a hard sealing structure. The second generation product needs to be sealed by a raw material tape during installation, so that the use is inconvenient.

For example, chinese patent CN201921339260 provides a sealing connection structure of a pipe, which includes a connector arranged outside the pipe, the end of the connector is provided with a plurality of sealing rings at intervals, an inner annular surface of each sealing ring is provided with a pressure reducing inclined surface, and the inclination directions of the pressure reducing inclined surface and the pressure reducing inclined surface are kept consistent; a locking cap is arranged outside the connecting piece, and a clamp point convex ring for applying clamping force to hydraulic pressure is formed on the outer surface of the middle end part of the connecting piece; the locking cap is characterized in that a horn-shaped flaring structure is formed in one end of the locking cap, the pipe is located in the connecting piece in a preassembly state, an outer port of the flaring structure of the locking cap is in contact with the connecting piece, when the hydraulic pliers exert force and act on the locking cap and the pliers point convex ring at the same time, the connecting piece is extruded into the locking cap after passing through the flaring structure of the locking cap to form a connecting and sealing structure between the connecting piece and the pipe. The invention has high connection strength, good sealing effect and long service life; the whole connecting structure is stable, the machining procedures are few, the machining precision requirement is low, and the machining cost is greatly reduced.

However, the joint provided by the patent does not solve the problem that the joint needs to be sealed by using the raw material tape, and the joint still needs two persons to be installed smoothly. In addition, the pipe sealing connection structure provided in the patent includes a plurality of components arranged in a dispersed manner, which is also inconvenient in production and installation processes.

And chinese patent CN201320477581.9 discloses a stainless steel pipe connection joint, which includes double links, elbows and tees. This nonrust steel pipeline attach fitting, including public end nut, card key, sealing washer and female end nut, public end nut installs the one end at the pipeline, female end nut passes through on the internal thread of public end nut with public end nut threaded connection, public end nut inner wall with be equipped with between the pipeline card key with the sealing washer, be equipped with the delivery port on the public end nut. The utility model discloses a cooperation through public end nut and female end nut is connected, and card key fixed position, and the sealing washer is sealed for the junction sealing performance is good, and has better anticreep effect. The card key 3 in this patent is two semi-circular card keys, and the middle part of card key 3 is provided with dop 8, is provided with aperture 9 near the tip at pipeline 5, and the dop 8 of card key inserts in aperture 9. The sealing rings are three, namely two hard sealing rings 4 and one soft sealing ring 7, and the soft sealing ring 7 is positioned in the middle of the hard sealing ring 4.

The stainless steel pipe coupling provided in this patent also includes a plurality of components arranged in a dispersed manner, and is completely sealed by a sealing ring.

Therefore, there is a need in the art to provide a new pipe joint and a new connecting method to solve the above problems.

Disclosure of Invention

The invention provides a method for connecting a pipe joint and a pipeline, wherein the pipe joint is used for being connected with at least one metal pipeline, the pipe joint comprises an integrally arranged metal main body, the metal main body sequentially comprises an internal connection section (1), a hard seal shrinkage section (2) and a non-shrinkage section (3) from the inner end to the outer end in the axial direction, the metal pipeline is inserted into the pipe joint from the outer end to the inner end of the metal main body of the pipe joint, and then a radial shrinkage force is applied by means of a tool to enable the shrinkage section of the pipe joint to shrink and be locked on the outer wall of the metal pipeline from outside to inside in the radial direction; the inner connecting section (1) comprises an inner connecting part (11) with a cylindrical outer wall and a pipe end blocking step (12) for blocking the axial end part of the metal pipeline, the hard sealing and tightening section (2) comprises a hard sealing and tightening part (21) with a cylindrical outer wall and a first convex ring (22), the first convex ring (22) is arranged on the inner wall of the hard sealing and tightening section (2) and protrudes annularly from the inner wall of the hard sealing and tightening section (2) to the radial inner side of the hard sealing and tightening section, the non-tightening section (3) comprises a non-tightening part (31) with a cylindrical outer wall and an annular groove (32), the annular groove (32) is arranged on the inner wall of the non-tightening section (3) and is recessed annularly from the inner wall of the non-tightening section (3) to the radial outer side of the non-tightening section, and the annular groove (32) is used for accommodating a sealing ring (5); after a radial reducing force is applied to the pipe joint by means of a tool, the convex ring is used for radially and inwards pressing the convex ring on the outer wall of the metal pipeline to form a first defense line for connecting and sealing the pipe joint and the metal pipeline, and the sealing ring is used for forming a second defense line for connecting and sealing the pipe joint and the metal pipeline.

In a specific embodiment, the metal main body further comprises a second convex ring (23), the second convex ring (23) is also arranged on the inner wall of the hard seal shrinkage section (2) and protrudes from the inner wall of the hard seal shrinkage section (2) to the radial inner side of the hard seal shrinkage section in an annular protruding mode, the first convex ring (22) and the second convex ring (23) are arranged in the axial direction of the pipe joint in a front-back mode, the first convex ring (22) is close to the inner end of the metal main body, and the second convex ring (23) is close to the outer end of the metal main body.

In a particular embodiment, the metal body further comprises an end-tightening section (4) arranged at an axially outer end of the non-tightening section (3), the end-tightening section (4) comprising an end-tightening portion (41) for providing a direct contact position for the tool to apply a radial tightening force; in the connecting method, the tool wraps the hard sealing tightening part (21) and the end tightening part (41) respectively, the tool provides radial tightening force for the hard sealing tightening section (2) and the end tightening section (4) simultaneously, and the outer diameter of the end tightening section (4) is smaller than or equal to that of the inner connecting section (1); the end part tightening section (4) forms a plurality of circumferentially dispersed end part tightening points (42) after the tool is applied with force and tightened.

In a particular embodiment, the pipe joint comprises a metal body and a sealing ring (5), preferably a rubber O-ring, arranged in the annular groove.

In a specific embodiment, the outer diameters of the inscribed section (1), the hard seal shrinkage section (2) and the non-shrinkage section (3) are sequentially increased.

In a specific embodiment, the pipe joint is an elbow joint, the elbow joint is used for connecting two metal pipelines, the elbow joint comprises an integrally arranged metal main body, the metal main body comprises two groups of axial main bodies, each group of axial main body sequentially comprises an inner connecting section (1), a hard seal shrinkage section (2) and a non-shrinkage section (3) from the axial inner end to the outer end of the axial main body, and the elbow main body is integrally arranged between the two inner connecting sections (1), so that an included angle of 10-170 degrees is formed between the axial leads of the two groups of axial main bodies; preferably, the metal elbow joint is L-shaped as a whole, namely, an included angle of 90 degrees is formed between the axial leads of the two groups of axial main bodies.

In a specific implementation mode, the coupling is interior screwed joint, interior screwed joint is used for linking to each other with metal pipeline and tap, interior screwed joint is including the metal main part that the integration set up, still include the interior screwed joint main part that the integration set up among the metal main part, interior screwed joint main part with inscription section (1) and the equal coaxial setting of hard seal crimple section (2), interior screwed joint main part sets up the one end relative with hard seal crimple section (2) on inscription section (1), be provided with the internal thread on the interior screwed joint main part, be used for interior screwed joint links to each other with tap.

In a specific implementation mode, the coupling is outer silk joint, outer silk joint is used for linking to each other with metal pipeline and tap, outer silk joint is including the metal main part that the integration set up, still including the outer silk main part that the integration set up among the metal main part, outer silk main part with inscription section (1) and the equal coaxial setting of hard seal crimple section (2), outer silk main part sets up the one end relative with hard seal crimple section (2) on inscription section (1), be provided with the external screw thread on the outer silk main part, be used for outer silk joint links to each other with tap.

In a specific embodiment, the pipe joint is a metal tee joint, the tee joint is used for connecting three metal pipelines, the tee joint comprises an integrally arranged metal main body, the metal main body comprises three groups of axial main bodies, each group of axial main bodies sequentially comprises an inner connecting section (1), a hard seal shrinkage section (2) and a non-shrinkage section (3) from the axial inner end to the outer end of the axial main body, and the tee main bodies are integrally arranged among the three inner connecting sections (1), so that the axial leads of the three groups of axial main bodies form included angles of 10-170 degrees in pairs; preferably, the metal three-way joint is integrally T-shaped, namely, two groups of axial main bodies are linearly arranged at an angle of 180 degrees between the axial leads of the two groups of axial main bodies, and the axial leads of the two groups of axial main bodies form an included angle of 90 degrees with the axial lead of the other group of axial main bodies.

In a specific implementation mode, the pipe joint is a metal straight-through joint, the straight-through joint is used for connecting two metal pipelines, the straight-through joint comprises an integrally arranged metal main body, the metal main body comprises two groups of axial main bodies, each group of axial main body sequentially comprises an inner connecting section (1), a hard sealing shrinkage section (2) and a non-shrinkage section (3) from the axial inner end to the outer end of the axial main body, and the straight-through main body is integrally arranged between the two inner connecting sections (1) or the two inner connecting sections (1) are directly and coaxially butted, so that the axial leads of the two groups of axial main bodies form 180 degrees.

In a specific embodiment, the outer diameters of the inscribed section (1), the hard seal shrinkage section (2) and the non-shrinkage section (3) are sequentially increased.

By the arrangement, metal raw materials used by the pipe joint can be saved to the maximum extent under the condition of completely realizing the functions of the pipe joint.

The invention has at least the following beneficial effects:

1) the sealing effect is good: the pipe joint product disclosed by the invention is mainly sealed by hard sealing and assisted by soft sealing of the O-shaped ring, and a raw material belt is not required for joint filling in the installation process, so that the installation is more convenient, the sealing effect is better, and the product performance is stronger.

2) The pipeline joint product corresponding to the connecting method is light, and the raw material cost is greatly saved.

3) During installation, the end part of the metal pipeline cannot fall off from the pipe joint, and the number of installation workers is saved.

4) Although the sealing ring is still used in the invention, the sealing ring only plays a role of backup and safety sealing, and the hard sealing contraction section is arranged at the axial inner end of the sealing ring, so the sealing ring is not contacted with water and air in general, and is not easy to age and damage.

In general, the invention adopts a soft and hard seal combination mode for the first time, wherein the hard seal belongs to a riveting process between metals, thereby avoiding plastic filling and solving the problem of hidden water leakage caused by aging of plastic or rubber sealing rings; wherein soft seal can ensure the product at first and further ensure the sealing stability of product when the deformation is bent in the transition, promotes the factor of safety of water pipe to the safety of guarantee water. And the soft seal can correspondingly save the labor amount for installing the joint.

Drawings

Fig. 1 is an external view of a pipe joint according to the present invention, which is a straight joint.

Fig. 2 is a schematic cross-sectional view of the pipe joint of fig. 1 according to the present invention.

Fig. 3 is an external view of the pipe joint shown in fig. 1 and 2 after the pipe joint is tightened using a tool.

Fig. 4 is a schematic cross-sectional view of the pipe joint shown in fig. 1 and 2 after the pipe joint has been tightened using a tool.

Fig. 5 is a schematic external view of another pipe joint according to the present invention, which is a straight-through joint.

Fig. 6 is a schematic cross-sectional view of the pipe joint shown in fig. 5 according to the present invention.

Fig. 7 is an external view of the pipe joint shown in fig. 5 and 6 after the pipe joint is tightened using a tool.

Fig. 8 is a schematic cross-sectional view of the pipe joint shown in fig. 5 and 6 after being tightened using a tool.

Fig. 9 is an external view of a pipe joint according to the present invention, which is an internally threaded joint.

Fig. 10 is a schematic cross-sectional view of the pipe joint shown in fig. 9 according to the present invention.

Fig. 11 is an external view schematically showing another pipe joint according to the present invention, which is an internally threaded joint.

Fig. 12 is a schematic cross-sectional view of the pipe joint of fig. 11 according to the present invention.

Fig. 13 is an external view of a pipe joint according to the present invention, which is an elbow joint.

Fig. 14 is a schematic cross-sectional view of the pipe joint shown in fig. 13 according to the present invention.

Fig. 15 is an external view of another pipe joint according to the present invention, which is an elbow joint.

Fig. 16 is a cross-sectional view of the pipe joint of fig. 15 according to the present invention.

Fig. 17 is an external view of a pipe joint according to the present invention, which is a three-way joint.

Fig. 18 is a schematic cross-sectional view of the pipe joint of fig. 17 according to the present invention.

Fig. 19 is an external view schematically showing another pipe joint according to the present invention, which is a three-way joint.

Fig. 20 is a cross-sectional view of the pipe joint of fig. 19 according to the present invention.

Detailed Description

As shown in fig. 1 to 20, the present invention provides a pipe joint and a method for connecting the pipe joint to a pipe, the pipe joint is used for connecting at least one metal pipe, the pipe joint comprises an integrally arranged metal body, the metal body comprises an inner connecting section (1), a hard sealing shrinking section (2) and a non-shrinking section (3) in sequence from an axial inner end to an axial outer end, the metal pipe is used for being inserted into the pipe joint from the outer end to the inner end of the metal body of the pipe joint, and then a radial shrinking force is applied by means of a tool to cause the shrinking section of the pipe joint to shrink from outside to inside in a radial direction and be locked on the outer wall of the metal pipe; the inner connecting section (1) comprises an inner connecting part (11) with a cylindrical outer wall and a pipe end blocking step (12) for blocking the axial end part of the metal pipeline, the hard sealing and tightening section (2) comprises a hard sealing and tightening part (21) with a cylindrical outer wall and a first convex ring (22), the first convex ring (22) is arranged on the inner wall of the hard sealing and tightening section (2) and protrudes annularly from the inner wall of the hard sealing and tightening section (2) to the radial inner side of the hard sealing and tightening section, the non-tightening section (3) comprises a non-tightening part (31) with a cylindrical outer wall and an annular groove (32), the annular groove (32) is arranged on the inner wall of the non-tightening section (3) and is recessed annularly from the inner wall of the non-tightening section (3) to the radial outer side of the non-tightening section, and the annular groove (32) is used for accommodating a sealing ring (5); after a radial reducing force is applied to the pipe joint by means of a tool, the convex ring is used for radially and inwards pressing the convex ring on the outer wall of the metal pipeline to form a first defense line for connecting and sealing the pipe joint and the metal pipeline, and the sealing ring is used for forming a second defense line for connecting and sealing the pipe joint and the metal pipeline.

The pipe joint product arranged integrally can be thrown integrally before installation and cannot be scattered. Therefore, the transportation is more convenient, and the installation is also more convenient.

In the invention, the end part shrinking section 4 forms more than three hoop points which are uniformly dispersed in the circumferential direction after being shrunk by applying external force, and the shrinking section and the hoop points can prevent the metal pipeline from rotating or falling off in the axial direction.

In the present invention, the metal body of the pipe joint is formed by, for example, a metal casting method.

In the invention, the materials of the metal pipeline and the pipe joint can be selected from stainless steel, copper or cast iron freely.

The invention provides a third generation metal pipe joint product, which is connected with a metal water pipe without filling gaps with raw material tapes.

The invention has at least the following characteristics:

1) sealing the joint and the pipeline: the first seal is a hard seal, and in particular is one or two metal rings projecting inwardly from the radially inner side wall of the metal body, and if two metal rings are provided, the two metal rings are arranged one behind the other in the axial direction of the pipe joint. The second seal is a soft seal, in particular an O-ring arranged axially outward of the metal ring. Therefore, the O-shaped ring only plays a role of safety, and the O-shaped ring can not contact liquid in the pipeline generally, so that the service life of the O-shaped ring is greatly prolonged. The O-shaped ring has two other functions, one is that when the pipeline is bent by more than 30 degrees for installation, the original hard seal is easy to lose efficacy, and the O-shaped ring plays a main sealing effect. The other is that when the pipe joint is installed on the pipeline, the O-shaped ring has elasticity, the end part of the metal pipeline is inserted into the pipe joint to form friction with the O-shaped ring, and the metal pipeline can be effectively prevented from slipping out to fall out of the pipe joint, so that the pipe joint can be installed by only one worker. The existing pipe joint needs to be held by one person during installation, and the other person can operate a tool to assemble the joint.

2) The metal main body is integrally arranged, so that the total length of the pipe joint can be shorter, materials are saved, and the cost of raw materials is saved.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions and substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.