KR102438797B1 - Pipe expansion apparatus for easy tube insertion, and composite pipe manufacturing method using the same - Google Patents

Abstract

A tube expansion device according to the present invention inserts a tube into an inner tube in a state where the outer diameter of the tube is reduced to make insertion of the tube easy, and expands the tube after insertion of the tube to insert the inner tube into an outer tube in a state where the inner tube is closely fixed to the tube to make the insertion of the inner tube easy. The expansion device (100) comprises: a frame (120) formed long along the longitudinal direction; a tube (110) installed to surround the frame (120) and having a sealed inner space (111); circular panels (117, 118, 119) installed at both ends of the tube (110) in the longitudinal direction to support the tube (110); and a main pipe (130) installed to pass through the tube (110) and the circular panels (117, 118, 119) along the longitudinal direction of the tube (110).

Description

Pipe expansion apparatus for easy tube insertion, and composite pipe manufacturing method using the same}

The present invention relates to a tube expansion device for expanding and combining an inner tube and an outer tube, and more specifically, since the tube is inserted into the inner tube in a state in which the outer diameter of the tube is reduced, the tube insertion is made easily and after inserting the tube into the inner tube It relates to a tube expansion device in which the inner tube is easily inserted by expanding the tube and inserting the inner tube into the outer tube in a state in which the inner tube is closely fixed to the tube.

In addition, the present invention also includes a method for manufacturing a composite pipe using such a pipe expansion device.

In general, a steel pipe or a cast iron pipe has been widely used as a large-scale pipe for water supply. The cast iron pipe has a problem that rust and scale generated inside the pipe cause deterioration of water quality. In order to solve this problem, the inner surface of the cast iron pipe is coated with cement or epoxy resin, etc., but the cement and the epoxy resin fall off, contaminating water and clogging the pipe.

Although cast iron pipes have problems as described above, there was no pipe that could surpass the excellent physical properties of cast iron pipes against water pressure or water shock acting on large pipes, so cast iron pipes have been continuously used as pipes for water supply inevitably.

However, the government or local governments have invested a huge amount of money in water purification plants to provide clean water, but due to the above problems with cast iron pipes, households are reluctant to drink tap water without using a water purifier. .

On the other hand, stainless steel pipe has excellent corrosion resistance and good taste of water, so it can be used as a pipe for water supply, but its price is high and its use is extremely limited due to problems such as soil corrosion (dislocation corrosion, etc.) in some areas.

However, since everyone acknowledges that a stainless steel tube is most suitable for drinking water, a stainless steel tube is used, but a low price and high strength tube is required.

The present applicant has developed a large composite pipe in consideration of this point. As shown in FIG. 1 , the large composite pipe 1 includes a stainless steel pipe 3 , a steel pipe 2 , and an anticorrosive layer 4 , a resin layer, and a stainless steel pipe 3 inside the steel pipe 2 . ) is inserted, and then the stainless steel pipe 3 and the steel pipe 2 are expanded. In order to increase the bonding force between the stainless steel pipe 3 and the steel pipe 2 , an adhesive layer (not shown in the drawing) may be formed between the stainless steel pipe 3 and the steel pipe 2 .

However, the large composite pipe 1 has a problem that the stainless steel pipe 3 and the steel pipe 2 can be separated from each other at both ends of the pipe.

In order to solve the above problems, the present applicant has developed a composite pipe 10 as shown in FIG. 2 and applied for it as Korean Patent Application No. 10-2020-0143991. All contents contained in the application specification and drawings of this application are incorporated herein by reference.

The composite pipe 10 includes a body portion 11 and a single tube portion 12 coupled to one end of the body portion 11 .

The body portion 11 includes a steel pipe (outer tube), a stainless steel tube (inner tube) inserted into the steel tube, and an anticorrosive layer (resin layer, not shown in the drawings) formed on the outer surface of the steel tube.

The steel pipe (external pipe) and the stainless steel pipe (inner pipe) are joined by expansion. In addition, along with the expansion of the pipe, an adhesive layer may be formed between the steel pipe (outer pipe) and the stainless steel pipe (inner pipe) to increase the bonding force. In addition, the adhesive layer may be made of polyurea subjected to plasticization heat treatment.

An expansion pipe 14 may be formed at the other end of the main body 11 . The expanded tube portion 14 is a portion in which the other end of the main body portion 11 is expanded, and is a portion into which the end tube portion 12 of the adjacent composite tube 10 is inserted when the composite tube 10 is connected to each other.

The short tube portion 12 is made of a stainless steel tube having a shorter length than the body portion 11 . The side of one end of this stainless steel pipe is welded to the side of one end of the steel pipe (exterior) so that it is watertight. A groove 13 is formed in the single tube portion 12 along the circumferential direction, and a connection device (not shown in the drawing) for connecting the composite tube 10 is installed in the groove 13 . The contents of the groove 13 and the connection device are disclosed in Korean Patent Registration No. 10-2264918, which the present applicant has already registered. All contents disclosed in the Patent Registration Publication of Korean Patent Registration No. 10-2264918 are incorporated herein by reference.

Since the short pipe part 12 has substantially the same thickness as the steel pipe (outer pipe) of the body part 11, the stainless steel pipe (inner pipe) of the body part 11 is in a substantially straight state without bending or stepping at a large angle. may be coupled to the inner surface of the short pipe portion 12 by welding while maintaining the . Therefore, it is possible to solve the above-described problem, that is, the problem that the steel pipe (outer pipe) and the stainless steel pipe (inner pipe) of the composite pipe are separated.

The anticorrosive layer (resin layer, not shown in the drawing) covers the outer surface of the steel pipe (outer face) to prevent corrosion of the steel pipe (outer face). Preferably, the anticorrosive layer (resin layer) is formed to extend just before the groove 13 . Since the outer portion of the groove 13 (the opposite portion of the body portion) is inserted into the expanded tube portion 14 , the anticorrosive layer may not be formed.

The anticorrosive layer (resin layer) may be made of polyurea. In this case, it may be made of two layers, namely, the first and second polyurea layers. Preferably, both the first and second polyurea layers and the adhesive layer (the adhesive layer formed between the steel pipe and the stainless steel pipe) are made of polyurea, and after the polyurea is applied, it is heated to 180-320° C., which is a temperature at which plasticization occurs. Accordingly, an interface film is respectively formed in the portion in contact with the outside air and the portion in contact with the exterior of the first and second polyurea layers, and since the interfacial film has smaller pores than other portions of the first and second polyurea layers, the water resistance and waterproofness will be improved. can The first and second polyurea layers and the adhesive layer subjected to the plasticization heat treatment in this way have excellent bonding strength, adhesion strength, and water resistance to the adherend (steel pipe and stainless steel pipe) compared to the existing ones.

On the other hand, as described above, the steel pipe (outer tube) and the stainless steel tube (inner tube) are coupled by expansion. The expansion of the pipe can be made by hydroforming, in which the hydroforming is performed by inserting a stainless steel pipe (inner pipe) into the inside of the steel pipe (outer pipe), then inserting the tube into the stainless steel pipe (inner pipe), and then pouring water into the tube. By injecting and expanding, the stainless steel tube (inner tube) and steel tube (outer tube) are expanded and combined.

However, if the difference between the outer diameter of the tube and the inner diameter of the stainless steel tube (inner tube) is large, the tube must be expanded a lot during expansion, so the service life of the tube is shortened, the working time is long, and the expansion force required for expansion is small. Accordingly, it is preferable that the difference is smaller. However, if this difference is small, there is a problem in that it is difficult to insert the tube into the stainless steel tube (inner tube) and it is difficult to take out the tube from the stainless steel tube (inner tube) after the tube expansion process is completed.

In addition, in the pipe expansion process, the process of inserting the stainless steel pipe (inner pipe) into the inside of the steel pipe (outer pipe) and the process of inserting the tube into the stainless steel pipe (inner pipe) are performed separately, so the process takes a lot of time and the operation is complicated. There are also problems.

The present invention is proposed to solve this problem, and in the tube expansion process for manufacturing the composite tube 10, the tube can be easily inserted into the stainless steel tube (inner tube), and after the tube expansion is completed, the tube is inserted into the stainless steel tube ( The purpose is to provide an expansion device that can be easily removed from the inner tube).

Another object of the present invention is to insert the tube into the stainless steel tube (inner tube), move the tube in this state, insert the stainless steel tube (inner tube) into the steel tube (outer tube), and then expand the tube to improve the inner and outer appearance An object of the present invention is to provide an expanding device that reduces work time and simplifies work by expanding the tube.

Another object of the present invention is to provide a pipe expansion device that reduces the possibility of collision with a steel pipe when inserting the inner tube into the steel tube (outer tube) by fixing the inner tube by expanding the tube after inserting the tube into the stainless steel tube (inner tube). .

Another object of the present invention is to provide a method for manufacturing a composite pipe using such an expansion device.

In order to achieve the above object, the tube expansion device 100 according to a preferred embodiment of the present invention, a frame 120 formed long in the longitudinal direction; The tube 110 is installed to surround the frame 120 and has a sealed inner space 111; Circular panels 117, 118, 119 installed at both ends of the tube 110 in the longitudinal direction to support the tube 110; and a main pipe 130 installed to pass through the tube 110 and the circular panels 117, 118, and 119 along the longitudinal direction of the tube 110. It may include.

An air supply unit, a vacuum pump, a water supply unit, a drain valve, and an air outlet may be respectively connected to the main pipe 130 .

The vacuum pump discharges the air in the inner space 111 to the outside so that the outer diameter of the tube 110 is reduced. In a state in which the outer diameter of the tube 110 is reduced by the vacuum pump, the tube 110 is inserted into the inner tube 11c.

After the tube 110 is inserted into the inner tube 11c, the air supply unit supplies air to the tube 110 and the tube 110 expands, so that the inner tube 11c is fixed in close contact with the tube 110, and in this state, the inner tube ( 11c) is inserted into the outer shell 11a.

The main pipe ( It may include a blocking plate 133 installed inside the 130). The first auxiliary pipe 131 is closer to the water supply than the second auxiliary pipe 132 .

The blocking plate 133 is installed inside the main pipe 130 and blocks the movement of water and air. The main pipe 130 is divided into a first part 136 on the water supply side and a second part 137 on the air outlet side around the blocking plate 133 . The water supplied through the water supply unit and the first part 136 is discharged to the inner space 111 through the first auxiliary pipe 131 , and the air in the inner space 111 is mixed with the second auxiliary pipe 132 and the second auxiliary pipe 132 . 2 is discharged to the outside through the portion 137 and the air outlet.

Another aspect of the present invention, the composite pipe manufacturing method, (a) reducing the outer diameter of the tube 110 by discharging the internal air of the tube 110 to the outside using a vacuum pump; (b) inserting the tube 110 into the inner tube 11c while the outer diameter of the tube 110 is reduced; (c) in a state in which the tube 110 is inserted into the inner tube 11c, inserting the inner tube 11c into the outer tube 11a; And, (d) after step (c), supplying water to the inside of the tube 110 to expand the tube 110 to expand the inner tube 11c and the outer tube 11a so that they are coupled; may include

Before the step (b), the step of preparing a pipe in which the side of one end of the short pipe portion 12 is watertightly welded to the side of one end of the exterior 11a; may further include. The inner tube 11c may extend further toward the inside of the short tube portion 12 than the outer tube 11a.

Then, after step (d), the extended portion of the inner tube 11c may be welded to the inner surface of the short tube portion 12 . The inner tube 11c and the short tube portion 12 are made of a material having greater corrosion resistance than the outer tube 11a, and the inner surfaces of the inner tube 11c and the short tube portion 12 are exposed to the liquid flowing therein.

The single tube portion 12 has a shorter length than the inner and outer tubes 11c and 11a, and a groove 13 is formed on the outer surface of the short tube portion 12 along the circumferential direction, and the groove 12 has a neighboring composite tube. A connecting device for connecting (10) may be installed.

Between the steps (b) and (c), (b1) supplying air to the inside of the tube 110 and expanding the inner tube 11c to closely fix the inner tube 11c to the tube 110; may be included. Step (c) may be performed in a state in which the inner tube 11c is fixed to the tube 110 by the step (b1).

The air supply unit supplies air to the tube 110 in step (b1), and the vacuum pump discharges the air inside the tube 110 to the outside in step (a). When the water supply tank supplies water to the tube 110 in the step (d), the internal air flows to the outside through the second auxiliary pipe 132 and the second part 137 of the main pipe 130 and the air outlet 134f. is discharged, and the pressurized water supply device supplies water by applying pressure so that the inner and outer tubes 11c and 11a are expanded.

In the step (d), (d1) supplying water to the inside of the tube 110 to fill the tube 110 with water, the internal air of the tube 110 by the water being filled through the air outlet 134f to be discharged; And, (d2) after the step (d1), lock the air outlet (134f) and use a pressurized water supply device so that the inner and outer tubes (11c, 11a) can be expanded and coupled to the inside of the tube (110). It may include; supplying while applying pressure.

The present invention has the following effects.

First, in the tube expansion process for manufacturing the composite tube 10, the tube 110 can be easily inserted into the inner tube 11c, and after the tube expansion is completed, the tube 110 can be easily taken out from the inner tube 11c.

Second, after inserting the tube 110 into the inner tube 11c, the tube 110 is expanded with air to fix the inner tube 11c, and then the tube 110 is moved to attach the inner tube 11c to the outer tube 11a. By inserting and then expanding the tube 110 with water to expand the inner and outer tubes 11c and 11a, it is possible to reduce the working time and simplify the operation.

Third, by inserting the tube 110 into the inner tube 11c and then expanding the tube 110 with air to fix the inner tube 11c, when inserting the inner tube 11c into the outer tube 11a, the outer tube 11a and reduce the chance of collision.

Fourth, to provide a method for manufacturing a composite pipe using such a pipe expansion device.

1 is a view showing a cross-section of a large composite pipe developed by the present applicant.
Figure 2 is a perspective view showing another composite tube developed by the present applicant.
Figure 3 is a perspective view showing a tube expansion device according to a preferred embodiment of the present invention.
4 is a cross-sectional view showing a tube expansion device.
5 is a cross-sectional view showing a state in which the inner air of the tube is discharged by the vacuum pump and the outer diameter of the tube is reduced.
Figure 6a is a cross-sectional view showing a state in which the single tube portion and the exterior constituting the composite tube are combined.
Figure 6b is a cross-sectional view showing the inner tube is inserted into the interior of the exterior.
7 is a cross-sectional view showing that the tube is inserted into the inner tube in a state in which the outer diameter of the tube is reduced.
8 is a cross-sectional view showing that the tube is expanded by supplying air to the tube after the tube is inserted into the inner tube.
9 is a cross-sectional view showing that the inner tube is inserted into the outer tube in a state in which the tube is inserted into the inner tube.
Figure 10 is a cross-sectional view showing a state in which water is filled in the tube through the filling valve after the inner tube is inserted into the outer tube and the air inside the tube is discharged to the outside.
11 is a cross-sectional view showing that the inside and outside of the tube are expanded by supplying water to the tube using a pressurized water supply device after the tube is filled with water by the filling valve to a predetermined level.
12 is a cross-sectional view showing that water is discharged to the outside after the expansion of the tube is completed.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention. Accordingly, the embodiments described in the present specification and the configurations shown in the drawings are merely embodiments of the present invention and do not represent all of the technical spirit of the present invention, so various equivalents that can be substituted for them at the time of the present application It should be understood that there may be variations and variations.

Hereinafter, the structure and operation method of the tube expansion device will be described by taking the composite tube 10 manufacturing process as an example. However, the structure and operation method of the tube expansion device is not limited to the manufacture of the composite tube 10 and may be applied to the production of other composite tubes, which will be readily apparent to those skilled in the art with reference to the following specification.

[Expansion device]

Figure 3 is a perspective view showing a tube expansion device according to a preferred embodiment of the present invention, Figure 4 is a cross-sectional view of the tube expansion device, Figure 5 is a cross-sectional view showing a reduced outer diameter of the tube.

As shown in the figure, the tube expansion device 100 includes a cylindrical frame 120 and a tube 110 installed to surround the cylindrical frame 120 and having a sealed inner space, and along the longitudinal direction of the tube 110 . It includes a main pipe 130 installed to pass through the tube 110 , and at least two auxiliary pipes 131 and 132 branched upward and downward from the main pipe 130 , respectively.

The cylindrical frame 120 includes a cylinder 121 and a support 126 .

The cylinder 121 has both ends open and has a cylindrical shape. The support 126 is installed to pass through the cylinder 121 to support the cylinder 121 . The cylinder 121 is connected to and supported by the support 126 by a plurality of first connecting materials (not shown in the drawing).

The cylinder 121 has an outer diameter that is slightly smaller than the inner diameter of the tube 110 . Therefore, when the tube 110 is in an expanded state, the tube 110 maintains a state spaced apart from the surface of the cylinder 121 and the air in the inner space 111 is discharged by the vacuum pump, so that the outer diameter of the tube 110 is In this reduced state, the tube 110 and the cylinder 121 may be in contact.

In addition, both ends of the cylinder 121 and the support 126 maintain a spaced apart state from the circular panel 117 .

The tube 110 is made of a material capable of expansion and contraction, for example, silicone, rubber, or the like, and has a sealed inner space 111 . When water or air is introduced into the inner space 111, the tube 110 is expanded, and when water or air is discharged to the outside, it is restored to its original shape, and the air in the inner space 111 by a vacuum pump (not shown in the drawing). is discharged and the pressure of the inner space is lower than the atmospheric pressure, it contracts and the outer diameter is reduced.

On the other hand, in the case of expansion using a pipe expansion mold, not a tube, both ends of the pipe should be sealed to be watertight. However, when the interior and exterior must be expanded at the same time while the interior of the exterior has an inner tube, it is very difficult or impossible to make both ends of the interior and exterior watertight. In contrast, in the expansion using the tube 110 , since the tube itself expands and there is water in the tube, it is possible to expand the inside and outside of the tube at the same time.

The tube 110 has a shape elongated in the longitudinal direction. In addition, both longitudinal ends of the tube 110 are supported by circular panels 117 , 118 , 119 . The circular panel 117 is installed inside the tube 110 and the circular panels 118 and 119 are installed on the outside of the tube 110, and the inner and outer circular panels 117, 118 and 119 are It is coupled by a bolt (117a). With this structure, the circular panels 117 , 118 , and 119 maintain and support the shape of both ends of the tube 110 .

The main pipe 130 is installed to pass through the tube 110 and the cylindrical frame 120 and the circular panels 117, 118, and 119 along the longitudinal direction of the tube 110 . The main pipe 130 is connected to and supported by the support 126 by a plurality of second connecting materials (not shown in the drawing), and the position thereof is fixed. The main pipe 130 preferably has strength and rigidity sufficient to support the load of the pipe expansion device 110 .

A plurality of branch pipes 134a, 134b, 134c, 134d, and 134e are installed on one side of the main pipe 130 and an air outlet 134f is installed on the other side. In addition, a barrier material 133 is installed inside the main pipe 130 , and the barrier material 133 will be described below.

Each of the branch pipes 134a, 134b, 134c, 134d, and 134e is connected to and communicates with the main pipe 130 . Specifically, an air valve is installed in the first branch pipe 134a to control the supply of air (preferably compressed air), and a vacuum valve is installed in the second branch pipe 134b to provide a vacuum pump (not shown in the drawing). ), and a pressure valve is installed in the third branch pipe 134c to control the supply of pressurized water (water having a pressure capable of expanding the inside and outside of the tube). In addition, a water filling valve is installed in the fourth branch pipe 134d to control the supply of water, and a drain valve is installed in the fifth branch pipe 134e to control discharging the water inside the tube to the outside. And, an air discharge valve is installed in the air discharge port (134f) to control the air discharge.

The main pipe 130 may be divided into a first part 136 and a second part 137 based on the blocking material 133 .

The air supplied through the air valve is moved to the first auxiliary pipe 131 through the first part 136, and the air in the internal space 111 is discharged through the first part 136 by the vacuum pump, The pressurized water supplied by the pressurized water supply device and the pressurized valve moves to the first auxiliary pipe 131 through the first part 136 , and the water in the internal space 111 is discharged to the outside through the first part 136 . do. And, the second part 137 is a part in which the air of the internal space 111 moves when the internal space 111 is filled with water.

The barrier material 133 is a member installed in the main pipe 130 between the first and second auxiliary pipes 131 and 132, and may be made of a material through which water and air do not pass, for example, rubber, silicone, plastic, etc. have. Accordingly, the air supplied through the first branch pipe 134a, the water supplied through the fourth branch pipe 134d, and the pressurized water supplied through the third branch pipe 134c are blocked by the blocking material, so It cannot move to the second part 137 and is discharged into the inner space 111 through the first part 136 and the first auxiliary pipe 131 . On the other hand, when water is supplied through the fourth branch pipe 134d, as water is filled in the internal space 111, the air in the internal space 111 is supplied with the second auxiliary pipe 132, the second part 137, and the air. It is discharged to the outside through the outlet 134f and does not move to the first part 136 .

As described above, in the pipe expansion device 100 according to the present invention, one main pipe 130 is divided into two parts in the longitudinal direction and each serves its role, thereby simplifying the device and supporting the load of the device.

The first and second auxiliary pipes 131 and 132 are respectively branched upward and downward from the main pipe 130 . Although two auxiliary pipes 131 and 132 are shown in the drawing, the number of auxiliary pipes may be increased as necessary.

The first auxiliary pipe 131 branches downward, and the second auxiliary pipe 132 branches upward. In addition, the blocking material 133 is installed in the main pipe 130 between the first and second auxiliary pipes 131 and 132 .

The first auxiliary pipe 131 includes air supplied through the air valve (first branch pipe), water supplied through the filling valve (fourth branch pipe), and pressure supplied through the pressure valve (third branch pipe). The pressurized water is discharged into the inner space 111 . Then, when the air in the internal space 111 is discharged to the outside using a vacuum pump (installed in the second branch pipe), the first auxiliary pipe 131 and the first part 136 and the second branch pipe 134b is emitted through

The first auxiliary pipe 131 is installed to pass through the cylinder 121 . When the air in the inner space 111 is discharged to the outside using a vacuum pump, the tube 110 is in close contact with the inlet of the first auxiliary pipe 131 so that the inlet is not completely sealed. (not shown in the drawing) is preferred. That is, since the tube 110 is made of silicon or rubber and has a certain rigidity, if the inlet of the first auxiliary pipe 131 has irregularities, even if the tube 110 is in close contact with the inlet, the inlet is not completely sealed. .

The second auxiliary pipe 132 is branched upward from the main pipe 130 . It is preferable for the second auxiliary pipe 132 to have a height close to the tube 110 for air exhaust and shorten the time of the tube expansion process, but the inlet of the second auxiliary pipe 132 is closed by the tube 110 . Since air cannot be discharged when sealed, it is preferable to determine the length of the second auxiliary pipe 132 in consideration of this.

[Method for manufacturing composite pipe using pipe expansion device]

Then, a method of manufacturing the composite pipe 10 will be described below with reference to FIGS. 5 to 12 .

First, a tube ( FIG. 6a ) and an inner tube ( 11c of FIG. 6b ) in which the single tube portion 12 and the outer tube 11a are coupled are prepared, respectively. Grooves 13 are continuously formed on the outer surface of the short pipe portion 12 in the circumferential direction. And, the side surface of one end of the short pipe portion 12 is welded to the side surface of one end of the outer tube 11a so as to be watertight. It is preferable that the short tube portion 12 and the outer tube portion 11a have substantially the same thickness.

The exterior 11a may be a steel pipe having excellent strength. An adhesive layer 11b is formed on the inner surface of the exterior 11a. Meanwhile, the adhesive layer 11b may be formed on the outer surface of the inner tube 11c or may be formed on both the outer surface of the inner tube 11c and the inner surface of the outer tube 11a. The adhesive layer 11b may be made of polyurea, and the adhesive layer 11b bonds the inner and outer surfaces 11c and 11a together with an expansion tube to be described later. Preferably, the polyurea adhesive layer 11b may be heated to a temperature (180 to 320° C.) at which plasticization of polyurea occurs after the tube expansion is completed, and the adhesive layer heated to this temperature has excellent adhesion and adhesion compared to conventional ones. do.

The inner tube 11c is coupled to the outer tube 11a by a subsequent tube expansion process. Since the inner tube 11c and the short tube portion 12 are in direct contact with the fluid flowing therein, they may be made of a material having excellent corrosion resistance, for example, stainless steel.

Then, a vacuum pump (not shown in the drawing) is connected to the second branch pipe 134b and then operated to discharge the internal air of the tube 110 to the outside. At this time, the air outlet 134f is in a closed state (the air outlet valve is closed). The internal air is discharged to the outside through the first auxiliary pipe 131 , the first portion 136 , and the second branch pipe 134b. 5 shows a state in which the outer diameter of the tube 110 is contracted by this process.

Next, as shown in FIG. 7 , the tube 110 is inserted into the inner tube 11c while the outer diameter of the tube 110 is contracted. Since the outer diameter of the tube 110 is in a contracted state, the insertion operation can be made easily and quickly.

After inserting the tube 110 into the inner tube 11c, as shown in FIG. 8 , by injecting air into the tube 110 to expand the tube 110 , the inner tube 11c is fixed in close contact with the tube 110 . do. The air injection may be performed by supplying compressed air through the first branch pipe 134a while the air outlet 134f is closed. Compressed air is supplied to the inner space 111 through the first branch pipe 134a, the first portion 136, and the first auxiliary pipe 131.

In this way, when the inner tube 11c is inserted into the outer tube 11a in a state in which the inner tube 11c is fixed to the tube 110, the position of the inner tube 11c is easily adjusted, so the possibility of collision between the inner tube 11c and the outer tube 11a This decreases and the insertion operation becomes easier. 9 shows this insertion process.

Next, as shown in FIG. 10 , water is injected into the tube 110 through the fourth branch pipe 134d (addition valve) in a state in which the air outlet 134f is opened. This water is injected rapidly and in large quantities with no pressure applied. The water is discharged into the inner space 111 through the fourth branch pipe 134d, the first part 136, and the first auxiliary pipe 131 to fill the inner space 111 and remove the air in the inner space 111. It is discharged to the outside through the second auxiliary pipe 132, the second portion 137, and the air outlet (134f).

When water starts to be discharged through the air outlet 134f, as shown in FIG. 11, after closing the air outlet 134f, pressurized water is supplied to the tube 110 through the third branch pipe 134c and the pressure valve. . Pressurized water is water supplied by applying pressure, and the pressurized water has a pressure sufficient to expand the inner and outer tubes 11c and 11a. A red arrow in FIG. 11 indicates the pressure applied by the pressurized water. By the expansion of the tube, the inner and outer surfaces 11c and 11a are closely coupled.

When expansion is complete, close the pressure valve and open the drain valve to discharge water to the outside. For rapid discharge, a drainage pump (not shown) may be connected to the fifth branch pipe 134e. When the drainage is completed, the tube 110 is taken out.

On the other hand, when the expansion of the pipe is completed, an expansion part ( 14 in FIG. 2 ) may be formed at the other end of the body part 11 . The expanded tube portion 14 is a portion into which the single tube portion 12 of the adjacent composite tube 10 is inserted when the composite tube 10 is connected to each other.

After the pipe expansion portion 14 is formed, a polyurea resin layer (anticorrosive layer) may be formed on the outer surface of the exterior surface 11 . Preferably, the resin layer may be formed in two steps. In addition, the resin layer may be heated to 180 ~ 320 ℃ the temperature at which the plasticization of the polyurea occurs. The resin layer heat-treated at this temperature is superior to the conventional adhesive, adhesion and corrosion resistance.

1: Composite pipe 2: Steel pipe 3: Stainless steel pipe
4: Anticorrosive layer (resin layer) 10: Composite pipe 11: Body part
11a: exterior 11b: adhesive layer 11c: interior tube
12: single pipe part 13: groove 14: expanded pipe part
100: tube expansion device 110: tube 111: inner space of the tube
117, 118, 119: round panel 117a: bolt
120: cylindrical frame
121: cylinder 126: support 130: main pipe
131: first auxiliary pipe 132: second auxiliary pipe
133: barrier material 134a: first branch pipe 134b: second branch pipe
134c: third branch 134d: fourth branch 134e: fifth branch
134f: air outlet 136: first part 137: second part

Claims (7)

(a) reducing the outer diameter of the tube 110 by discharging the internal air of the tube 110 of the tube expansion device 100 to the outside using a vacuum pump;
(b) allowing the tube 110 to be inserted into the inner tube 11c while the outer diameter of the tube 110 is reduced;
(c) in a state in which the tube 110 is inserted into the inner tube 11c, the inner tube 11c being inserted into the outer tube 11a; and,
(d) after step (c), supplying water to the inside of the tube 110 to expand the tube 110 to expand the inner tube 11c and the outer tube 11a so that they are combined; and ,
Between steps (b) and (c),
(b1) supplying air to the inside of the tube 110 to expand the inner tube 11c in close contact with the tube 110; is included,
Step (c) is made in a state in which the inner tube 11c is closely and fixed to the tube 110 by the step (b1),
Step (d) is,
(d1) supplying water to the inside of the tube 110 to fill the tube 110 with water, so that the air inside the tube 110 is discharged through the air outlet 134f by the filled water; and,
(d2) After the step (d1), the air outlet 134f is locked and water is supplied to the tube 110 by using a pressurized water supply device so that the inner and outer tubes 11c and 11a can be expanded and coupled. supplying; (a) reducing the outer diameter of the tube 110 by discharging the internal air of the tube 110 of the tube expansion device 100 to the outside using a vacuum pump;
(b) allowing the tube 110 to be inserted into the inner tube 11c while the outer diameter of the tube 110 is reduced;
(c) in a state in which the tube 110 is inserted into the inner tube 11c, the inner tube 11c being inserted into the outer tube 11a; and,
(d) after step (c), supplying water to the inside of the tube 110 to expand the tube 110 to expand the inner tube 11c and the outer tube 11a so that they are combined; and ,
Before the step (b), the side of one end of the short pipe portion 12 is prepared for a pipe joined to be watertight by welding to the side of one end of the exterior 11a;
The inner tube 11c extends further toward the inside of the short tube portion 12 than the outer tube 11a,
After step (d), the extended portion of the inner tube 11c is welded to the inner surface of the short tube portion 12,
The inner tube 11c and the short tube portion 12 are made of a material with greater corrosion resistance than the outer tube 11a, and the inner surfaces of the inner tube 11c and the short tube portion 12 are directly exposed to the liquid flowing therein,
The single tube portion 12 has a shorter length than the inner and outer tubes 11c and 11a, and a groove 13 is formed on the outer surface of the short tube portion 12 in the circumferential direction, and the groove 13 has a neighboring composite tube. (10) A method for manufacturing a composite pipe, characterized in that a connecting device for connecting is installed. According to claim 1,
A polyurea adhesive layer 11b is formed between the inner tube 11c and the outer tube 11a, and the polyurea adhesive layer 11b bonds the inner and outer tubes 11c and 11a to 180, which is a temperature at which plasticization of polyurea occurs. A method of manufacturing a composite pipe, characterized in that it is made by heating to 320 ℃. According to claim 1,
The tube expansion device 100,
frame 120;
The tube 110 is installed to surround the frame 120 and has a sealed inner space 111;
a main pipe 130 installed to pass through the tube 110 in the longitudinal direction of the tube 110; and,
Includes; first and second auxiliary pipes 131 and 132 respectively branched from the main pipe 130 to the upper side and the lower side;
The main pipe 130 is connected to an air supply unit, a vacuum pump, a pressurized water supply device, a water supply tank, a drain valve, and an air outlet, respectively.
The air supply unit supplies air in step (b1), and the vacuum pump discharges the internal air of the tube 110 to the outside in step (a),
When the water supply tank supplies water to the tube 110 in the step (d), the internal air flows to the outside through the second auxiliary pipe 132 and the second part 137 of the main pipe 130 and the air outlet 134f. A method of manufacturing a composite pipe, characterized in that the pressurized water supply device supplies water by applying pressure so that the inner and outer pipes (11c) (11a) are expanded. 3. The method of claim 2,
Step (d) is,
(d1) supplying water to the inside of the tube 110 to fill the tube 110 with water, so that the air inside the tube 110 is discharged through the air outlet 134f by the filled water; and,
(d2) After the step (d1), the air outlet 134f is locked and water is supplied to the tube 110 by using a pressurized water supply device so that the inner and outer tubes 11c and 11a can be expanded and coupled. supplying; In the tube expansion device for expanding and coupling the inner tube (11c) and the outer tube (11a),
Frame 120 formed long along the longitudinal direction;
The tube 110 is installed to surround the frame 120 and has a sealed inner space 111;
Circular panels 117, 118, 119 installed at both ends of the tube 110 in the longitudinal direction to support the tube 110; and,
A main pipe 130 installed to pass through the tube 110 and the circular panel 117, 118, 119 along the longitudinal direction of the tube 110;
The main pipe 130 is connected to an air supply unit, a vacuum pump, a water supply unit, a drain valve, and an air outlet, respectively,
The vacuum pump discharges air in the inner space 111 to the outside so that the outer diameter of the tube 110 is reduced, and the tube 110 is inserted into the inner tube 11c in a state in which the outer diameter of the tube 110 is reduced, and the tube After the 110 is inserted into the inner tube 11c, the air supply unit supplies air to the tube 110 so that the tube 110 is expanded so that the inner tube 11c is fixed in close contact with the tube 110, and in this state the inner tube 11c ) is a tube expansion device, characterized in that it is inserted into the exterior (11a). 7. The method of claim 6,
The main pipe ( 130) including a blocking plate 133 installed inside, the first auxiliary pipe 131 is closer to the water supply than the second auxiliary pipe 132,
The main pipe 130 is divided into a first part 136 on the water supply side and a second part 137 on the air outlet side around the blocking plate 133,
The water supplied through the water supply part and the first part 136 is discharged to the inner space 111 through the first auxiliary pipe 131 , and the air in the inner space 111 is discharged to the second auxiliary pipe 132 and the second Expansion device, characterized in that discharged to the outside through the portion 137 and the air outlet.

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