KR20070014224A - Resin-lined cast iron pipe(s) and manufacturing method therefor - Google Patents

Abstract

A main steel pipe with a resin liner and a manufacturing method thereof are provided to sanitarily supply the water without toxic material and to completely block corrosion of the steel pipe by mounting the resin pipe flange at one end of the resin pipe. A main steel pipe with a resin liner comprises a resin pipe(1) inserted in the main steel pipe; and an end protrusion(1e) formed at one end of the resin pipe; and a rear end protrusion(1f) of the resin pipe to prevent the fluid from contacting the main steel pipe. The resin liner in the main steel pipe is integrally welded through the medium of an adhesive resin. The resin liner is applied with a preparatory tension by a shaft journal to minimize deformation according to the temperature change.

Description

Cast iron pipe with resin liner and its manufacturing method {RESIN-LINED CAST IRON PIPE (S) AND MANUFACTURING METHOD THEREFOR}

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a longitudinal sectional view showing a conventional cast iron pipe (for single piece).

Figure 2 is a longitudinal cross-sectional view of the lining is performed on the cast iron pipe (for one piece) according to the present invention.

3 is a longitudinal cross-sectional view of a cast iron pipe (for single use) subjected to lining according to the present invention.

Figure 3a is a conceptual diagram showing the assembly relationship between the resin pipe ring groove and the resin pipe and the cast iron pipe of the elastic ring according to the present invention.

Figure 3b is a sectional view and a front view of the elastic ring according to the present invention.

Figure 3c is a sectional view and a front view showing another embodiment of the elastic ring according to the present invention.

Figure 4 is a process chart of the cast iron pipe (for piece) subjected to the lining according to the present invention.

5 is a conceptual view of the resin tube crushed by shrinking according to the present invention.

6 is a conceptual diagram of inserting the reduced diameter resin tube according to the present invention into a cast iron tube.

7 is a conceptual view of another embodiment in which the shaft diameter of the resin pipe according to the present invention and the insertion into the cast iron pipe are continuously performed.

8 is a conceptual view of pressing the inserted resin pipe according to the present invention in close contact with the cast iron pipe in the longitudinal direction.

9 is a conceptual view of adjusting the stress of the resin tube by pressing the resin tube pressed against the cast iron tube according to the present invention in the circumferential direction again.

10 is a conceptual diagram in which the pressure roller according to the present invention moves in the longitudinal direction in the resin pipe.

11 is an example of another embodiment of the pressure roller according to the present invention.

12 is a conceptual view of injecting the resin tube joint step and terminal jaw of the cast iron pipe according to the present invention.

13 is a conceptual diagram for heating the inside of the cast iron pipe according to the present invention.

14 is a conceptual view of fusion welding the resin pipe joint step and the terminal jaw of the cast iron pipe according to the present invention.

Fig. 15 is an example of another embodiment of the process of the cast iron pipe (sewage pipe) in which the lining according to the present invention is performed.

Fig. 16 is an example of another embodiment of fusion of a cast iron pipe (piece), which is lined with the present invention;

Explanation of symbols on the main parts of the drawings

1: Resin Tube 1a: Reduced Resin Tube

1b: Resin tube being restored 1c: Pressed resin tube

1d: Resin pipe outer diameter before shaft reduction 1e: Resin pipe joint step

1f: resin tube terminal jaw 1g: resin tube ring groove

2: cast iron pipe 2a: cast iron pipe joint

2b: cast iron pipe terminal

3: indenting body 3a: indenting body pressing means

3b: press-fit guide jig

4: fixed stand

5: clamp 5a: clamp actuator

5b: guide wheel

6: mobile cart 6a: support

6b: Rod 6c: Guide Rod

6d: cover clamp 6e: rail

6f: Rod feed means

7 pressurizing means 7a pressurizing roller

7b: piston 7c: cylinder

7d: hollow body 7e: tool post

7f: Hollow body conveying means 7g: Supporting roller

8 heating means 8a furnace heating means

8b: furnace 8c: insulation

9: cooling means

10: fusion machine 10a: fusion machine pressurizing means

10b: external heating means 10c: end heating means

11: elastic ring (round) 11a: elastic ring (protrusion)

11b: protrusion

12: injection mold (joint part) 12a: injection tube

12b: outlet hole 12c: heating means (heating coil)

12d: cooling means

13: injection mold (terminal) 13a: injection tube

13b: exhaust hole 13c: heating means (heating coil)

13d: cooling means

14 hollow body 14a air shutoff valve

14b: air conduit 14c: fixed bracket

14d: tension rod 14e: air outlet

14f: pressure gauge

15: terminal cover flange 15a: discharge hole

15b: ring protrusion

16: joint cover flange 16a: discharge hole

16b: Vacuum chamber 16c: Vacuum valve

16d: annular projection 16e: vacuum conduit

The present invention relates to the lining of the purpose of corrosion protection in the inner surface of the knitting pipe in which one side of the pipe is partly inserted into the inside of the other pipe in the pipes used for the transport of constant, sewage, and other fluid of the cast iron pipe.

Cast iron pipe is mainly composed of cast iron pipe and concrete pipe. Cast iron pipe, which is mainly used for water use, is replaced by ductile cast iron pipe in gray cast iron pipe, and its corrosion resistance is greatly improved. However, there is a problem that rust occurs in long-term use. One example is the Republic of Korea Patent Registration 10-9261 [Cure method of cement mortar lining of steel pipe] (Registration date 1981,01,31) and then the Republic of Korea Patent Patent 10-20679 [Powder flow prevention method Immersion coating method] (registration date 1986,01,24) was introduced in Korea, but since the durability of the coating film did not reach the life of cast iron pipe, a synthetic resin coating method was developed. For example, Korean Patent No. 10-58879 [Corrosion resistant lining steel pipe and its manufacture] Method] (Registration date 1993,01,28) and Republic of Korea 20-189659 [Synthetic resin coating steel pipe] (Registration date 2000 , 05,09) and Republic of Korea Patent No. 10-375772 [Method of manufacturing synthetic resin coated iron pipe and Synthetic resin coated iron pipe produced by it] (Registration date 2003,02,28) and Republic of Korea Patent 10-426936 [Synthetic resin for water supply and sewage Manufacturing method of coated cast iron pipe] (registration date 2004,03,31), all of which are coated with powdered resin on the pipe wall and heated to the pipe wall to melt the powder to form lining. Repeated expansion and contraction of the resin due to this temperature change causes partial peeling from the tube and corrosion of the tube from this part, and some resins, especially epoxy resins, can elute bisphenol-A, the main component of the tube. This can cause health problems.

In spite of the above problems, the present invention is chemically stable and excellent in chemical resistance for corrosion prevention of cast iron pipes, which occupy a substantial portion of water pipes in the reality that corrosion resistance and low cost are difficult to find other alternative materials compared to steel pipes. It is harmless and especially non-polar, so non- anaerobic or oxidizing bacteria can use non-polar resin such as polyethylene for lining, but even though several pipes are connected, resin-lined cast iron is made so that the fluid flowing through the pipe contacts the resin lining only. The present invention provides a method for manufacturing a knitting tube.

In order to achieve the object of the present invention described above, the present invention is a resin pipe (1c) axially interpolated inside the cast iron pipe (2) and the resin pipe joint step (1e) and terminal jaw (1f) formed on one side of the resin pipe It provides a cast iron pipe having a resin liner on the inner surface, characterized in that the fluid does not contact the cast iron pipe, including).

Preferably, the resin pipe joint step 1e and the terminal step 1f may be fused to the resin pipe 1c and the end portions 2a and 2b of the cast iron pipe, and further include an elastic ring 11. can do. As another example, the resin tube joint step and the terminal jaw may be provided by welding the resin extrusion plate with a resin pipe.

In addition, the present invention in the manufacture of cast iron pipe having a resin liner therein, the manufacturing process of cast iron pipe and resin pipe; Shaft diameter and insertion process of resin tube; Pressure-adhering process to the inner peripheral surface of the cast iron pipe of the resin pipe; Injection process of resin tube joint step and terminal step; It provides a method for producing a cast iron pipe having a resin liner on the inner surface, characterized in that it comprises an inspection and delivery process.

In addition, the present invention in the manufacture of cast iron pipe having a resin liner therein, the manufacturing process of cast iron pipe and resin pipe; Heating process of cast iron pipe and resin pipe; Shaft diameter and insertion process of resin tube; A pressure fusion process on the inner circumferential surface of the cast iron pipe of the resin pipe; Injection process of resin tube joint step and terminal step; It provides a method for producing a cast iron pipe having a resin liner on the inner surface, characterized in that it comprises an inspection and delivery process.

Pressurized adhesion used in the present invention refers to a state in which the resin pipe is in close proximity to the inner wall of the cast iron pipe by simply applying a physical pressure (not close to the substance level), and the pressure fusion refers to a resin pipe, especially a non-polar polyethylene inner wall of the cast iron pipe. The part where it comes into contact with it is modified to have a polarized state, and a pressure is applied at a softening point, preferably at a temperature above the melting point, so that some ionic bond (molecular or atomic level) with the cast iron is formed.

Preferably, the resin pipe joint step 1e and the terminal step 1f may further include a resin pipe ring groove 1g, and the heating process of the cast iron pipe and the resin pipe may directly heat the inside of the cast iron pipe or It is preferable to directly heat the inside and outside of the cast iron pipe at the same time. In one embodiment of the present invention, the heating process of the cast iron pipe and the resin tube is preferably heated by any one of the electrical resistance wire, ultrasonic generator, flame.

The pressurized fusion process, for example, by inserting a pressure roller into the pressurizing means (7) inside the cast iron pipe to adjust the support roller (7g) for supporting and rotating the cast iron pipe in the lower part of the cast iron pipe and the pressure to adjust the pressure Composed of a pressure cylinder (7c) and a piston (7b) for transmitting the pressure to the roller is a way to apply pressure to the resin pipe by fusion through the roller inside the cast iron pipe, a further example of the pressure welding process, cast iron pipe Air pressure conduit 14b including a hollow body 14, an air outlet 14e attached thereto, a pressure gauge 14f, a shutoff valve 14a, a vacuum pump, and a shutoff valve 16c), a terminal cover flange 15 and a joint cover flange 16 including a vacuum conduit 16e including a vacuum chamber 16b and a packing and a blocking protrusion connecting the cast iron pipe 2 and the hollow body 14; ) And both ends of cast iron pipe Is composed of a nut and a tension rod (14d) to bind each cover flange to each other, and inserts a hollow body into the cast iron pipe to fill the air pressure and attach a vacuum chamber so that the discharge of air can occur continuously during the process By using a hollow body in the device to be a way to enable pressurization even with a small amount of air.

Hereinafter, the present invention will be described in detail.

The present invention not only prevents the occurrence of rust due to flowing water in a cast iron pipe having superior corrosion resistance compared to steel pipe, and also prevents the eluate from the coating or lining that protects the pipe or the pipe into the running water, thereby improving the safety of drinking water. The present invention relates to a cast iron pipe having a resin liner such as polyethylene inside the cast iron pipe and to a method for manufacturing the same. Especially in a resin such as epoxy, which has previously been used as a coating material for cast iron pipes, harmful substances such as environmental hormones that disturb a living body and the environment are Although it may be eluted, resins such as non-polar polyethylene are hygienic and safe, and therefore, the present invention relates to a cast iron pipe using the resin as a liner and a method of manufacturing the same. Hereinafter, polyethylene (PE), polybutylene (PB), and polyfluoropropylene (PP) are used. Non-polar resins such as The.

However, other resins are also within the scope of the present invention, and cast iron pipes have been described for example for single-handed use, but other flanged ones are also within the scope of the present invention.

 Conventionally, cement mortar lining or epoxy powder coating or coating was performed on the inside in a cast iron pipe for single use as shown in FIG. 1, but the present invention is intended for single use with resin lining such as polyethylene as shown in FIG. Presented a cast iron pipe.

On the other hand, Figure 3 shows the connected state of the cast iron pipe with the resin lining.

There are various methods of manufacturing the cast iron pipe with the lining, but the method is described below with reference to the drawings by way of several embodiments.

1.Example 1.

4 shows a process diagram according to an example of the basic embodiment, which firstly comprises a process for producing a cast iron pipe and a resin pipe; Shaft diameter and insertion process of resin tube; Pressure-adhering process of resin tube; Resin pipe flange injection process; It consists of the inspection and release processes, which are presented in detail in the order of each process.

1a. The production of cast iron pipes and resin pipes;

The cast iron pipe (2) is manufactured by a known method, and the dust or other contaminants are washed or sand blasted if necessary, and the resin pipe (1) is also manufactured by extrusion of a synthetic resin by a known method, the synthetic resin in particular in the embodiment of the polyethylene ( PE), polybutylene (PB), or polyflopropylene (PP), and the outer diameter (1d) of the resin pipe is manufactured to a certain amount larger than the inner diameter of the cast iron pipe, and the predetermined amount is about 1/100 to the thickness of the thickness of the resin pipe. It should be in the range of the thickness of the resin pipe, but preferably in the range of 1/10 to 1/3 of the thickness of the resin pipe, the length of which is necessary to hold the resin pipe by the clamp 5, which is a fixing means at a length that requires the lining of the cast iron pipe. It is manufactured by adding length and processing allowance.

Making the resin pipe larger than the inner diameter of the cast iron pipe imparts greater preliminary stress to the resin pipe when the shrinkage and expansion caused by the temperature change are applied to the resin pipe, so that the resin pipe is stressed only in one direction, thereby affecting the temperature. This is to minimize the resin tube so as not to peel off from the cast iron tube.

1b. Shaft diameter and insertion of resin tube;

         When the resin tube manufactured in the shaft diameter conceptual diagram of FIG. 5 is pressed and crushed by the indenter 3, the circumferential length of the resin tube is the same, but the apparent outer diameter thereof is reduced. The end of the side from which the insertion of the rod is started is fixed with a plurality of clamps 5 attached to the end of the rod 6b and the guide rod 6c of the movable trolley 6 moving back and forth on the rail 6e. Advance and pull out to insert into cast iron pipe.

  When the resin pipe is inserted to the position where the lining of cast iron pipe is required, stop the moving cart, loosen the clamp, advance the rod and guide rod, and remove the clamp from the cast iron pipe.

As another example of the shaft diameter and insertion, as shown in the conceptual diagram of FIG. 7, a plurality of terminals of the resin tube crushed in a state where only a part of the resin tube is crushed by local indentation instead of the whole resin tube at the position immediately before the resin tube is inserted into the cast iron tube. When the resin pipe is pulled into the cast iron pipe by inserting the resin pipe into the cast iron pipe by advancing the rod feed means 6f or the moving cart 6 for fixing the clamp 5 and transferring the clamp, the resin pipe is continuously crushed and inserted into the shaft.

1c. Press-fitting of the resin tube;

When the clamp 5 is removed after the resin tube is inserted, the resin tube is restored to its original shape, that is, while being expanded in a round shape, but because the resin tube is larger than the cast iron tube, the resin tube cannot be completely restored, and only a part 1b of the resin tube as shown in FIG. 8 is shown. Since it comes in contact with the cast iron pipe, the pressing roller 7a, which is one of the pressurizing means 7, is pushed into the resin pipe 1b to pressurize the resin pipe to force against the inner wall of the cast iron pipe 2.

In Fig. 8, the pressing means moves the radially pressurized roller 7a attached to the end of the hollow body 7d, which moves forward and backward by the hollow feeder 7f attached to the moving cart 6, and moves it in the radial direction. It consists of the piston 7b and the cylinder 7c.

The pressure roller is pushed against the wall of the cast iron pipe while straightening the curved resin pipe while reciprocating in the longitudinal direction of the resin pipe by the hollow body conveying device 7f.

When the resin tube is in close contact with the cast iron pipe to some extent, the pressing means is removed, and this time, the pressure adjusting device shown in FIG. 9 is inserted into the resin tube in the same manner as the pressing means, and the resin tube is bent by rotating about the hollow body 7d. Uniformly adjust the strain remaining stresses in the lost and uneven areas.

If all parts of the resin tube are in close contact with each other, the pressure adjusting device is removed, and the resin tube is inserted into the cast iron tube by cutting out the resin tube of the unnecessary clamping part and the processing margin with a cutting tool (not shown). And the step of injecting the resin tube terminal jaw 1f.

FIG. 10 is a conceptual view of conveying the pressing means shown in FIG. 8 and the pressure adjusting device shown in FIG. 9 in the longitudinal direction of the tube, and FIG. 11 illustrates a case in which the length of the tube is shorter than that of another embodiment of the pressing means. By pressing the cast iron pipe (2) rotated by the pressing means (7) having a length corresponding to the total length of the present invention provides a pressing means having a high productivity.

1d. Resin pipe flange injection;

As shown in FIG. 12, the injection molds 12 and 13 are closely attached to both ends of the resin tube, and the resin filling portion of the injection mold and the cast iron pipe is inserted into the injection mold at a temperature of 40 to 90 degrees, preferably at a temperature of 50 to 70 degrees. After heating with the heated means 13c and injecting the resin through the inlets 12a and 13a, the resin is filled in the space between the mold and the cast iron pipe, and the air staying in the space is discharged to the outside through the outlets 12b and 13b. After filling a certain amount of resin, the filling pressure is maintained, and after a while, the mold and the resin filled with the cooling means 12d and 13d inserted into the injection mold are cooled and solidified to some extent to remove the injection mold.

The elastic ring 11 is made of rubber or silicone having a high elasticity in an annular shape having a circular cross section or a protrusion 11b, so that the expansion of the cast iron pipe due to temperature change occurs. Prevent leakage into gaps between parts.

3A shows a state in which the elastic ring 11 is sandwiched in the resin tube ring groove, and a cross-sectional view and a front view of the elastic ring 11 having a circular cross section are shown in FIG. 3B, and a triangular protrusion 11b is provided in FIG. 3C. The cross section and the front view of the elastic ring are presented. In particular, the elastic ring provided with the projection has an excellent structure to prevent leakage due to the large elasticity that allows the projection to closely contact the resin pipe ring groove (1g).

The resin tube ring groove (1g in FIG. 3A) is an annular groove formed in the resin tube joint step 1e and the resin tube terminal step 1f to accommodate the elastic ring, which is smaller than the cross section of the elastic ring so that the elastic ring is always stuck. It is desirable to.

1e. Inspection and release;

After removing the resin scrap from the injection inlet 12a and the discharge hole 12b, the adhesive is bonded and then released.

2. Example 2

In Example 1, the resin tube joint step 1e and the terminal step 1f are injected into both ends of the resin tube with the shaft diameter inserted so as to be integrated with the resin tube so that the fluid does not touch the metal part at the joint part. Branch pipe joints and terminal jaws can be pre-injected from the mold and welded to the resin tube inserted in the shaft diameter, or extruded plates can be prepared in advance instead of injection and then welded to both ends of the resin tube. In this embodiment, the method is suitable for mass production.

The extruded plate is manufactured by extrusion, and the extruded plate manufactured in the shape of an annular flat ring by a punch or a cutting tool is attached to both ends of the resin tube which has been inserted and adhered. The extruded plate 1e or 1f is brought into contact with the resin plate. When the end is heated to the welding temperature and reaches the welding temperature, wait for a while while the welded part is pressurized and then cool it to complete the welding.

The resin tube terminal jaw is shown in Fig. 14 to be welded in advance, or extruded and manufactured into a plate. The conceptual diagram of the resin tube terminal jaw is shown in FIG. It is natural to be able to weld in the same manner in view of the scope of the present invention.

3. The above embodiments 1 and 2 are economical when the pipe is low pressure, but the resin pipe is separated from the cast iron pipe when the high pressure is applied and when the negative pressure is formed, that is, when the fluid is sucked by the suction pump instead of the pressure pump. Since the force to crush is generated, it is preferable to fuse the resin pipe and the cast iron pipe to integrate them. An example of such a case is given.

Fusion process of the cast iron pipe with lining in the process diagram 2 shown in Figure 15 is a manufacturing process of cast iron pipe and resin pipe; Heating process of cast iron pipe and resin pipe; Resin tube shaft diameter and insertion process; Pressure bonding and welding process; Resin pipe flange attachment process; It consists of inspection and shipping process, which will be described in detail below with reference to the drawings.

3a. Manufacturing cast iron pipes and resin pipes;

The cast iron pipe is manufactured in a known manner as described in 1a above, but is washed and blasted, and the resin pipe is also manufactured in the same manner as described in 1a above, but the screw is rotated when a compound or pellet type resin is put into a hopper of an extruder (not shown). While being kneaded by and conveyed toward the die, the hollow resin is molded into the hollow body, while the adhesive resin injected into the other hopper is transferred and kneaded by the screw, and fed into the outer peripheral portion of the resin tube being formed into the hollow body to overlap with the resin tube. It is then kneaded, conveyed and extruded from the die.

The extruded resins are made of a resin tube in which an outer circumferential surface having a predetermined diameter and thickness is coated with an adhesive resin.

3b. Heating process of cast iron pipe and resin pipe;

The resin pipe is placed on the shaft and heated to its outer circumferential surface with a flame or electrical resistance wire. The resin pipe is heated above the temperature at which the resin pipe is easily bent, and the heating of the cast iron pipe is one of the hollow body conveying means 7f as shown in FIG. Heat the inner circumferential surface of the cast iron pipe directly by inserting a heating element, which is one of the cylindrical heating means 8 wound around the cylinder and the nichrome wire or tungsten wire, which is attached to the outer circumferential surface of the hollow body 14 connected to one side of the cylinder, to the inside of the cast iron pipe. Heat above the fusion temperature of the resin and use the heating element which is one of the furnace heating means 8a from the outside or clean gas so that the outer circumferential surface of the metal tube receives heat directly, but this external heating reduces the heat dissipation due to the internal heating. The heating process should be made of refractory bricks as much as possible as it is a secondary purpose to shorten the heating time and reduce the temperature difference between the inner and outer surfaces. It is preferable that it is made in the heating furnace 8b which has been soaked and sufficiently insulated with the heat insulator 8c.

The idea of the present invention is to present a method of precisely controlling the temperature of the welded portion while increasing the thermal efficiency and shortening the heating time by directly heating inside the thick cast iron pipe compared to other types of pipe (steel pipe, stainless steel pipe or copper pipe). Simultaneous heating at the outside of the cast iron pipe is to make the fusion evenly by smoothing the gradient of heat diffusion by the internal heating (small temperature deviation) for secondary purposes.

Since the internal heating means must be removed during the insertion of the resin tube, in addition to the fusion temperature in consideration of the cooling resulting from this, the heating is allowed to a sufficient temperature in consideration of the cooling during the operation.

3c. Shaft diameter and insertion of resin tube;

Shaft diameter and insertion are carried out in the same manner as described in 1b.

3d. Pressure bonding and welding process;

In FIG. 11, the roller is placed on the supporting roller 7g which rotates after heating and insertion, and is pressed by the pressing means 7 while rotating the cast iron pipe 2 in which the liner 1c is inserted, and supporting rollers 7g at both ends of the pressing roller. A device for adjusting the flow rate and pressure, not shown, connected to the control valve to adjust the pressure applied by the pressure cylinder to achieve optimum fusion.

As another example, when the length is longer than the diameter or the size of the pressure roller is uneconomical, the hollow body 7d reciprocating back and forth by the hollow body conveying means 7f to the inside of the cast iron pipe as shown in Figs. The pressing device (7, 7a, 7b, 7c) is pushed to the end of the head), and the resin pipe and the cast iron pipe are integrated when the pressure cylinder 7c is transferred from one end of the resin pipe to the other end while applying pressure necessary for welding. Will be fused.

The hollow body conveying means (7f) can be a more stable operation if the structure having a multi-stage piston so as to exhibit sufficient strength corresponding to the length of the cast iron pipe to be produced, the pressure cylinder (7c) and the piston (7b) ) Arranges a large number of them and arranges them in a radial or triangular or pentagonal shape so that the feed shaft does not bend during pressurization and can evenly press the inner surface of the cast iron pipe at a constant pressure. It should be of a size that can be used, and the pressure and flow rate supplied to cylinders of various types should be properly controlled according to the specifications of cast iron pipes.

As another example of the fusion pressurization process of the cast iron pipe, as shown in FIG. 16, the hollow body 14 is inserted into the cast iron pipe in the pressurization method and apparatus using a conventionally known air pressure, and the air outlet at the proper position of the hollow body. (14e) and to which an air conduit (14b) is coupled, which is connected to an air pressure pipe connected to a compressor (not shown) via a shutoff valve (14a) with a pressure gauge at a suitable place outside the hollow body, At both ends of the hollow body, cover flanges 15 and 16 are formed to support the hollow body in the cast iron pipe and have a packing to prevent leakage of pressure between the cast iron pipe and the hollow body, and the end portion of the cast iron pipe is annular so as not to touch the cover flange. Protrusions 15b and 16d are formed so that they are connected to the space formed at the end of the cover flange and the cast iron pipe, Covers are formed at both ends of the cast iron pipe, forming the air inlets 15a and 16a, connecting the vacuum pipe, attaching the vacuum gauge, and attaching the vacuum chamber 16b and the shutoff valve 16c, and connecting the vacuum pump and the conduit (not shown). As shown in the figure, the flange does not escape from the cast iron pipe even when pneumatic pressure is applied by the tension of several tension rods 14d.

Alternatively, the cover flange and the hollow body may be coupled to the hollow body by a fixing bracket 14c in place of the tension rod.

When assembled in the above configuration, before and after the heating for fusion or during heating, first press the predetermined pressure through the air discharge port attached to the hollow body, and then shut off the shutoff valve.The resin pipe is in close contact with the cast iron pipe and between the resin pipe and the cast iron pipe. When the valve on the vacuum side is opened, the air is discharged through the vacuum pipe.If the transfer is necessary for reasons such as heating, even if the shutoff valve on the vacuum side is closed, there is a certain amount of vacuum in the vacuum chamber. Will be removed.

In the actual implementation, a resin tube with a larger diameter than that of the cast iron tube is inserted in a shaft diameter, so that if the pressure of the air supplied between the hollow body and the resin tube is sufficient, the resin tube expands after some time even if the vacuum is omitted, and the cast iron tube The bubbles are gradually removed to the outside through the discharge holes (15a and 16a) while being in close contact with the inner wall of the.

3e. Injection of resin tube flanges;

Injection of the resin tube is carried out in the same manner as described in 1d above, but by adding a resin tube ring groove (1 g) into which the elastic ring 11 is inserted into the injection mold, thereby molding the sealing force of the resin having a relatively insufficient elastic force when the fluid flows at a high pressure. It becomes a structure to reinforce.

3f. Inspection and release;

It is carried out in the same manner as described in 1e.

The inside of the cast iron pipe, which constitutes the majority of the water pipe, is welded by inserting a resin pipe having a diameter larger than the inner diameter of the cast iron pipe, in particular polyethylene, polybutylene or polyfluoropropylene resin, and having a resin pipe flange at one end of the resin pipe. Compared with mortar lining or epoxy coating, resins such as polyethylene do not elute harmful substances, so they can supply tap water hygienically, completely prevent corrosion of cast iron pipes, and elastic rings are provided between the joints of cast iron pipes. This well-maintained and cast resin tube has a restoring force to swell, resulting in a cast iron tube with a lining that preserves long term adhesion strength.

In terms of the manufacturing method, the heating time is directly applied from the inside during the fusion process, so that the heating time is shorter than that of the conventional heating method, and in particular, the adhesion temperature during the fusion of the inner resin tube is easily controlled to improve the quality. It is possible to reduce the waste of energy as much as possible.

Claims (14)

A cast iron pipe having a resin liner on an inner surface thereof, wherein the resin tube is axially inserted into the cast iron pipe and a resin pipe joint step and a terminal jaw formed at one end of the resin pipe to prevent the fluid from contacting the cast iron pipe. The method of claim 1, Resin liner of the inner surface of the cast iron pipe is a cast iron pipe with a resin liner on the inner surface, characterized in that fused to the cast iron pipe through an adhesive resin. In claims 1 and 2, The resin liner of the inner surface of the cast iron pipe is a cast iron pipe having a resin liner on the inner surface, characterized in that the pre-stress is applied to the shaft diameter so that the deformation caused by the change in temperature is minimized. The method according to claim 1, wherein The resin pipe joint step and the terminal jaw is cast iron pipe having a resin liner on the inner surface, characterized in that the injection to the end of the resin pipe and cast iron pipe. The method according to claim 1, wherein The joint flange is a cast iron pipe having a resin liner on the inner surface, characterized in that it further comprises an elastic ring. The method according to claim 1, wherein The resin pipe joint step and the terminal jaw is a cast iron pipe having a resin liner on the inner surface, characterized in that the punched or cut extruded plate is provided by welding with the resin pipe. The method of claim 1, wherein The material of the resin lined inside the cast iron pipe is any one of polyethylene (PE), polyflopropylene, polybutylene, cast iron pipe with a resin liner on the inner surface. In the production of cast iron pipe having a resin liner therein, the manufacturing process of cast iron pipe and resin pipe; Shaft diameter and insertion process of resin tube; Pressure-adhesion process on the inner circumferential surface of cast iron pipe of resin pipe; Injection process of resin tube joint step and terminal step; Process for producing a cast iron pipe with a resin liner on the inner surface, characterized in that it comprises an inspection and delivery process. In the production of cast iron pipe having a resin liner therein, the manufacturing process of cast iron pipe and resin pipe; Heating process of cast iron pipe and resin pipe; Shaft diameter and insertion process of resin tube; A pressure fusion process on the inner circumferential surface of the cast iron pipe of the resin pipe; Injection process of resin tube joint step and terminal step; Process for producing a cast iron pipe with a resin liner on the inner surface, characterized in that it comprises an inspection and delivery process. The method according to claim 8 or 9, The method of manufacturing a cast iron pipe having a resin liner on the inner surface of the resin pipe joint step and the terminal jaw further comprises a resin pipe ring groove. The method of claim 9, The heating process of the cast iron pipe and the resin pipe is a method of manufacturing a cast iron pipe with a resin liner on the inner surface, characterized in that the direct heating of the inside of the cast iron pipe or a direct heating of the inside and outside of the cast iron pipe at the same time. The method of claim 9, The heating process of the cast iron tube and the resin tube is a method of manufacturing a cast iron tube having a resin liner on the inner surface, characterized in that the heating by any one of the electrical resistance line, ultrasonic generator, flame. The method of claim 9, The pressurized fusion process includes a pressure roller and a piston for inserting a pressure roller into the cast iron pipe to support and rotate the cast iron pipe at the bottom of the cast iron pipe, a control device for adjusting the pressure to pressurize, and a pressure cylinder and a piston to transmit the adjusted pressure to the roller. The method of manufacturing a cast iron pipe with a resin liner on the inner surface, characterized in that the inside of the cast iron pipe through the roller by applying pressure to the resin pipe. The method of claim 9, The pressurized fusion process is an air pressure pipe including a hollow body for reducing the amount of air to be filled in the cast iron pipe, an air discharge port and a pressure gauge, and a shutoff valve, and a vacuum pipe and a cast iron pipe including a vacuum pump, a shutoff valve, and a vacuum chamber. It consists of a cover flange including a packing connecting the hollow body and the hollow body and a nut and a tension rod which bind the cover flanges at both ends of the composite pipe to each other, and injects the hollow body into the composite pipe to fill the air pressure. Method of manufacturing a cast iron pipe with a resin lining on the inner surface, characterized in that it is possible to pressurize even a small amount of air using a hollow body in a device that allows the discharge of air continuously during the process by attaching a vacuum chamber .

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