KR102360328B1 - How to manufacture steel pipes for water supply - Google Patents

Abstract

The present invention relates to a steel pipe for water supply to supply tap water, and more specifically, to a method for manufacturing a steel pipe for water supply capable of manufacturing the steel pipe for water supply by performing a roulette step on an inner surface of the steel pipe, performing a short blast step, and performing a post-processing step; and improving durability of the steel pipe by increasing surface roughness of the inner surface of the steel pipe and improving adhesion and attaching strength of a paint. The method for manufacturing a steel pipe for water supply of the present invention comprises: (a) a step of mounting the steel pipe having a constant diameter in a rotating unit; (b) a step of performing roulette processing on the inner surface of the steel pipe mounted in the rotating unit in the (a) step; (c) a step of processing short blast on the inner surface of the roulette processed steel pipe in the (b) step; (d) a step of heating the short blast processed steel pipe in the (c) step and firstly to thirdly coating the outer surface of the steel pipe with a coating material; and (e) a step of coating the inner surface of the steel pipe in which the outer surface is coated with a coating material in the (d) step.

Description

{How to manufacture steel pipes for water supply}

The present invention relates to a steel pipe for water supply that supplies tap water. In more detail, the knurling process is first performed on the inner surface of the steel pipe, and then a shot blasting process is performed, followed by a subsequent process for water supply By manufacturing a steel pipe, the surface roughness of the inner surface of the steel pipe is increased, and thus the adhesion and adhesion strength of the paint are improved, and thus the durability of the steel pipe is improved.

In general, since the pipe for supplying tap water gradually deteriorates over time, various foreign substances contained in tap water are deposited as sludge, or rust is generated as the inner surface of the pipe is oxidized, and these are hardened to form a scale layer this will be made

Therefore, the most commonly applied coating and lining method is to prevent contamination and corrosion of water supply pipelines, and since this coating method directly affects the safety and lifespan of steel pipes, the quality of the paint used for painting And the technology of applying the paint to the steel pipe is very important.

In particular, since the quality of tap water flowing into the steel pipe for water supply has a direct impact on public health, it is stipulated that both domestic as well as overseas satisfy coating materials and coating technology above a certain quality standard. In the case of Korea, the national standard (KS D3565) for 'coated steel pipe for water supply', which accounts for most of the steel pipe for water supply, stipulates only 'liquid epoxy' as the inner coating material. There are cases where the coating film peels off, and since solvents containing components such as benzene and toluene are used, despite concerns about elution, it is still being used for water supply because an alternative coating material and technology have not been developed.

In addition, the coating method of performing a protective coating on the surface to protect the surface of the steel pipe is suggested in Korean Industrial Standards KSD3607 and KSD3589. In the case of Korean Industrial Standard KSD3607, a pre-treatment process is performed to mechanically or chemically remove grease, rust, and other foreign substances adhering to the original pipe, and after heating the pre-treated steel pipe to a constant temperature, the powdered polyethylene is melted Adopting the adhesive coating method.

On the other hand, in the case of KSD3589, after pretreatment, the outer surface of the steel pipe is heated in advance to apply an adhesive, and polyethylene is coated by an extrusion method. That is, in the conventional coating method, one or two layers of protective coating are applied to the outer surface of the steel pipe, and the coating method is divided into powder welding or extrusion.

As a coated steel pipe that has recently been in the spotlight, a steel pipe with a triple coating layer formed of a protective coating layer on the surface of an epoxy adhesive (FBE) layer, a polyethylene adhesive (PE Adhesive) layer and a polyethylene (PE) resin layer is used. have.

As a prior art of such a coated steel pipe, Korean Patent Registration No. 10-1402013 (an eco-friendly steel pipe coated with vegetable paint and a manufacturing method thereof) has been proposed.

In the prior art, a steel pipe having a shape according to the customer's request is manufactured from a straight pipe type original pipe using a cutter, a welding machine, etc. (S11), and a shot blasting device or a grit blasting device is used to By projecting multiple TY shots (grain used for shot blasting) or grit (grain pieces with sharp angles pulverized by a ball mill or hammer mill) on the inner and outer surfaces of the steel pipe manufactured in step (S11), Removes contaminants such as protrusions, scale, rust, and paint attached to the inner and outer surfaces (S12), and heats the steel pipe from which the contaminants are removed in step S12 in a chamber sealed from the outside (S13) , the first liquid and the second liquid are sequentially sprayed on the inner surface of the steel pipe (S14, S15), the first liquid and the second liquid are sequentially sprayed on the outer surface of the steel tube (S16, S17), and after cooling, the end A method of manufacturing an eco-friendly steel pipe in which the inner and outer surfaces of the steel pipe to be processed (S18, S19) are coated with a vegetable polyurethane paint is presented.

In addition, as a prior art for rehabilitating an aged fluid transport pipe, Korean Patent Registration No. 10-1525219 (a shot blasting device for rehabilitating an old pipe) has been proposed.

The prior art includes a vehicle body configured to be movable within a tube, a shot projector supported on the vehicle body and performing a shot blasting treatment on an inner surface of the tube, wherein the shot projector projects a shot onto the inner surface of the tube, the projector body, the A rear blocking wall assembly for limiting scattering on the rear side of the shot projected by the projector body from the rear of the projector body based on the traveling direction of the vehicle body, wherein the lower portion of the rear blocking wall constituting the rear blocking wall assembly includes a pipe There is proposed a shot blasting device provided with a shot outlet for moving a shot located in a lower region of the projector body to the rear by falling to the floor.

However, the "coated steel pipe for water supply" presented in the prior art uses a shot blasting device or a grit blasting device to remove contaminants such as protrusions, scale, rust, and paint attached to the inner and outer surfaces of the steel pipe, and then Although the inner and outer surfaces of the steel pipe are coated with polyurethane paint, there is a problem in that the adhesion of the inner surface of the steel pipe is lowered and the coating layer peels off during long-term use.

That is, when the coated steel pipe is used for a long period of time, the coated material is peeled off from the inside of the steel pipe and supplied for drinking water, and the steel pipe itself is corroded according to the peeling of the coating material, thereby contaminating the water supply.

Republic of Korea Patent Registration No. 10-0725731. Republic of Korea Patent Registration No. 10-0863152. Republic of Korea Patent Registration No. 10-1402013. Republic of Korea Patent Registration No. 10-1513995. Republic of Korea Patent Registration No. 10-1525219.

The present invention is a technology devised to improve the problems of the "coated steel pipe for water supply" presented in the prior art, and the knurling process is performed on the inner surface of the steel pipe, then the shot blasting process is performed, and the first to tertiary coatings are performed on the outer surface of the steel pipe. An object of the present invention is to provide a method of manufacturing a steel pipe for water supply, which is manufactured by coating the inner surface of the steel pipe with a coating material after performing the process.

In addition, the embodiment of the present invention increases the surface roughness of the inner surface of the steel pipe by performing the knurling process on the inner surface of the steel pipe, thereby improving the adhesion and adhesion strength of the coating material to further increase the durability of the steel pipe, while the long-term use of the steel pipe is possible. , An object of the present invention is to provide a method for manufacturing a steel pipe for waterworks that prevents contamination of waterworks.

The present invention is to realize the desired object as described above,

(a) mounting a steel pipe of a certain diameter to the rotating unit; (b) processing the inner surface of the steel pipe seated on the rotating part in the above step by knurling; (c) processing the shot blasting on the inner surface of the steel pipe knurled in the step; (d) heating the shot-blasted steel pipe in the step, and first to third coating the outer surface of the steel pipe with a coating material; and (e) coating the inner surface of the steel pipe coated with the outer surface in the above step with a coating material;

The step (b) is carried out with an inner surface processing apparatus for a steel pipe, the inner surface processing apparatus for a steel pipe, a support plate having a predetermined size and provided with a rail; a rotating part rotatably installed on the upper surface of the support plate by the operation of a driving motor; and a moving pressing unit that is movably installed along the rail while pressing the inner surface of the steel pipe rotated by the rotating unit;

A plurality of rollers rotatably installed in the longitudinal direction on the upper surface of the rotating unit; a driving motor for rotating the roller; Including; a support for stably supporting the roller;

The moving pressing unit includes a wheel moving along the bottom surface of the rail by rotation of the motor; a first frame movably installed on the upper surface of the rail; a second frame vertically fixed to the first frame; a knurled holder fixed toward the inner surface of the steel pipe at a predetermined height of the second frame; a third frame horizontally fixed to an upper end of the second frame; A cylinder installed on the lower part of the third frame and pressurizing the knurl holder; includes,

The knurl holder is composed of a horizontal bar having a predetermined length and a knurled portion coupled to the tip of the horizontal bar, and a vibrator is coupled to the horizontal bar and an intake pipe is coupled to the horizontal bar.

In addition, as an embodiment of the present invention, the vibrator is disposed on the upper side of the horizontal bar so as to be close to the knurled portion without contacting the steel pipe, and is coupled to the horizontal bar by a bracket.

In addition, as an embodiment of the present invention, the intake pipe is horizontally disposed below the horizontal bar so as not to contact the steel pipe, is coupled to the horizontal bar with a bracket, and is installed under the end portion close to the knurled portion. A ball is formed.

In an embodiment of the present invention, the knurling process is first performed on the inner surface of the steel pipe, then the shot blasting process is performed, and in the subsequent process, the first to tertiary coating processes are performed on the outer surface of the steel pipe, and then the inner surface of the steel pipe is coated with a coating material. By manufacturing the steel pipe for water supply, there is an effect of improving the adhesion and adhesion strength of the inner coating material to further increase the durability of the steel pipe for water supply.

In addition, the embodiment of the present invention increases the surface roughness of the inner surface of the steel tube by first performing the knurling process on the inner surface of the steel pipe, thereby improving the adhesion and adhesion strength of the coating material to prevent the initial peeling of the coating layer, thereby improving the durability of the steel tube. On the other hand, it is possible to use the steel pipe for a long time and has the effect of preventing contamination of the water supply.

In addition, in an embodiment of the present invention, the vibrator vibrates the knurled part in the vertical direction to form the groove part of the steel pipe more uniformly, and by sucking metal powder and foreign substances generated during the knurl processing operation and discharging it to the outside of the steel pipe, It has the effect of preventing respiratory diseases of workers and improving the working environment.

1 is a process diagram showing the manufacturing process of a steel pipe for water supply in the present invention.
Figure 2 is a perspective view showing the manufacturing process of the steel pipe for water supply in the present invention.
Figure 3 is a photograph showing the state of korret processing and shot blasting in the present invention.
Figure 4 is an internal photograph showing the coating state of the steel pipe in the present invention.
Figure 5 is a perspective view showing an inner surface processing apparatus for steel pipe for knurl processing in the present invention.
Figure 6 is a front view showing the inner surface processing apparatus for a steel pipe in the present invention.
7 is a plan view showing an inner surface processing apparatus for a steel pipe in the present invention.
8 is a cross-sectional view taken along line AA in FIG. 5;
9 is a front view showing the moving state of the knurl holder of the inner surface processing apparatus for steel pipe in the present invention.
10 is a front view of the main part showing the installation state of the knurled holder of the inner surface processing apparatus for steel pipe in the present invention.
11 is a front view of the main part showing the operating state of the knurled holder of the inner surface processing apparatus for steel pipe in the present invention.
12 to 13 are block diagrams showing a coating device for the inside of a steel pipe in the present invention.
14 is a test report showing the adhesion strength of a general steel plate.
15 is a test report showing the adhesion strength of the conventional shot blast-treated steel pipe.
16 is a test report showing the adhesion strength of the steel pipe treated with knurling and shot blasting in the present invention.

Prior to explaining the technical idea of the present invention in more detail using the accompanying drawings, 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 inventors themselves It should be interpreted as meaning and concept consistent with the technical idea of the present invention on the basis of the principle that the concept of a term can be appropriately defined in order to describe the invention of

Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all of the technical spirit of the present invention, so they can be substituted at the time of the present application It should be understood that various modifications may be made.

Hereinafter, the technical idea of the present invention will be described in more detail with reference to the accompanying drawings. Since the accompanying drawings are merely examples shown to explain the technical idea of the present invention in more detail, the technical idea of the present invention is not limited to the form of the accompanying drawings.

A method of manufacturing a steel pipe for water supply according to an embodiment of the present invention comprises the steps of: (a) seating a steel pipe of a certain diameter on the rotating part 20; (b) processing the inner surface of the steel pipe seated on the rotating part 20 in the above step by knurling; (c) processing the shot blasting on the inner surface of the steel pipe knurled in the step; (d) heating the shot-blasted steel pipe in the step, and first to third coating the outer surface of the steel pipe with a coating material; and (e) coating the inner surface of the steel pipe whose outer surface is coated in the above step with a coating material.

In the embodiment of the present invention, the steel pipe P for water supply is first seated on the rotating part 20 of the inner surface processing apparatus for steel pipe as shown in FIGS. 1 and 2 in the drawings. (S10) Here, the steel pipe P has an inner diameter It is about 300 to 3,600 mm, and in order to achieve the convenience of processing, it is provided, for example, with a pipe of about 6 m.

In the above, a knurling is performed on the inner surface of the steel pipe P seated on the rotating part 20. (S20) Due to this knurling process, as shown in FIG. 3A in the drawing, the inner surface of the steel pipe P is The groove is formed in a substantially rhombus shape, and the size of the rhombus shape is formed to a width of about 2 to 7 mm depending on the inner diameter size of the steel pipe (P), and the depth of the groove is preferably formed to be 0.1 to 0.5 mm.

In the above, it is most preferable that the size of the rhombus formed as a groove on the inner surface of the steel pipe P by the knurling has a width of 5 mm, and the depth of the groove is formed of 0.3 mm.

Next, shot blasting is performed on the inner surface of the steel pipe P which has been knurled in step S20. Similarly, a number of irregular grooves are generated on the inner surface and grooves of the rhombus shape formed by the knurling process.

Therefore, in contrast to the existing technology in which only shot blasting is performed on the inner surface of the steel pipe P, a more dense groove can be formed on the inner surface of the steel pipe P that has been subjected to knurl processing and shot blasting in the present invention.

As a result, by treating the inner surface of the steel pipe (P) with knurling and shot blasting, a denser groove is formed on the inner surface of the steel tube (P) to increase the surface roughness, so that the adhesion and adhesion strength of the coating material can be improved. .

Next, the steel pipe (P) that has been shot blasted in the step (S30) is heated, and the outer surface of the steel pipe (P) is first to thirdly coated with a coating material. (S40) (S50) (S60)

In the above step, the primary coating (S40) for coating the outer surface of the steel pipe (P) is produced as a powder epoxy adhesive (FBE; Fusion Bonded Epoxy) layer, and the secondary coating (S50) is a polyethylene adhesive (PE Adhesive) layer In addition, the tertiary coating (S60) is created as a polyethylene (PE) resin layer, so that a triple coating layer is formed on the outer surface of the steel pipe (P).

By forming a triple coating layer on the outer surface of the steel pipe (P) in the steps (S40) (S50) (S60), the durability and impact resistance of the steel pipe (P) for water supply are further improved, and corrosion of the steel pipe (P) is reduced. will prevent

Next, coating is performed on the inner surface of the steel pipe (P) whose outer surface is coated in the above step. (S70)

In the drawing, (A) of FIG. 4 shows that the coating was carried out by applying elvan solvent-free epoxy after korret processing in the step (S20), and in the drawing, (B) of FIG. It is coated by applying solvent-free epoxy.

4 (A) and (B) in the figure, the coating method on the inner surface of the steel pipe (P) is more dense in the method of coating by applying elvan solvent-free epoxy after the shot blasting treatment.

As a result, compared to the case where only the conventional shot blasting treatment was performed and coating was performed, in the present invention, the coating is performed after the knurling and shot blasting treatment to increase the surface adhesion strength of the coating material (P).

The surface roughness of the steel pipe (P) according to the embodiment of the present invention and the adhesion strength of the coating material are shown in Table 1 below, and the test results thereof are shown in FIGS. 12 to 14 in the drawings.

Next, the configuration and operation of the inner surface processing apparatus for steel pipe for carrying out the step (S20)) will be described.

As shown in FIG. 5 in the drawing, the inner surface processing apparatus for steel pipe for performing the knurl processing in the step (S20)) is a support plate 10 having a predetermined size and provided with a rail 11, an upper surface of the support plate 10 The rotating part 20 is rotatably installed by the operation of the driving motor 32 in the A portion 30 may be included.

In the present invention, as shown in FIGS. 5 to 8 in the drawings, the inner surface processing apparatus for a steel pipe performs knurl processing in a substantially rhombus shape to increase the surface roughness of the inner surface of the steel pipe 1 to increase the surface area of the painting or coating, Or to make the coating better.

In the above, the support plate 10 is made of a flat plate, the length of which may be of about 16 m, and the width of about 3 m, and the length and width of the support plate 10 may be different, of course. to be. In addition, it is possible to target a large-scale steel pipe 1 for water supply having a diameter of approximately 300 to 3,600 mm.

A plurality of rails 11 may be installed on the upper surface of the support plate 10 in the longitudinal direction. In the above-mentioned rail 11 , two rails 11 may be installed on one side of the support plate 10 , and two rails 11 may be installed on the other side of the support plate 10 .

A rotating part 20 capable of rotating the steel pipe 1 may be provided between the rails 11 in the above. The rotating part 20 is for rotating the steel pipe 1 placed on the upper surface of the roller 21 , and the rotating part 20 is a plurality of rollers 21 rotatably installed on the upper surface of the support plate 10 in the longitudinal direction. ), a driving motor 22 for rotating the roller 21, and a support 23 for stably supporting the roller 21 may be included.

The roller 21 may have a length equal to or longer than the length of the steel pipe 1 to be processed, and are positioned at positions spaced apart from each other by a predetermined distance on the left and right sides so that the steel pipe 1 can be rotated while stably supported. can be installed.

Of course, in the above, the two rollers 21 are installed so as to be rotated in the same direction by a gear, a chain, etc., which are power transmission means. In addition, since the steel pipe 1, which is a heavy object, is placed on the bottom surface of the roller 21, the support 23 may be installed on the bottom surface of the roller 21 to stably support the steel pipe 1 .

Meanwhile, in the above, the moving pressing part 30 is to increase the roughness of the inner surface of the steel pipe 1 while moving toward the inside of the steel pipe 1 along the rail 11 of the support plate 10 .

In the above, the moving pressing unit 30 is a wheel 31 moving along the bottom surface of the rail 11 by rotation of the motor 32 , and a first frame 33 movably installed on the upper surface of the rail 11 . , a second frame 34 fixed vertically to the first frame 33, a knurl holder 35 fixed toward the inner surface of the steel pipe 1 at a predetermined height of the second frame 34, the first A third frame 38 that is horizontally fixed to the upper end of the second frame 34, a cylinder 39 that is installed under the third frame 38 and presses the knurled holder 35 may be included. have.

In the above, the rail 11 may be formed of a conventional H-beam, and of course, a conventional rail 11 may be used. In addition, the wheel 31 may be movably installed on the bottom surface of the rail 11 , and a motor 32 for rotating the wheel 31 so that the moving pressing unit 30 is moved may be installed. That is, the motor 32 may be moved while rotating the wheel 31 .

In addition, the first frame 33 moving together with the wheels 31 may be installed on the upper surface of the rail 11 made of two pieces, and the first frame 33 may be installed in the width direction of the support plate 10 . .

Meanwhile, a second frame 34 having a vertical height may be fixed to the upper surface of the first frame 33 , and the inner surface of the steel pipe 1 is formed in a predetermined shape at a predetermined height of the second frame 34 . The knurled holder 35 may be installed horizontally.

Such a knurled holder 35 may include a horizontal bar 36 having a predetermined length and a knurled portion 37 coupled to the front end of the horizontal bar 36 .

In the above, the knurl part 37 is coupled to the horizontal bar 36 so as to be replaced, and is inserted into the horizontal bar 36 to be rotatably installed.

Such a knurled part 37 can form a rhombus-shaped groove with oblique lines crossing the inner surface of the steel pipe 1 obliquely in different directions, and can also form the inner surface of the steel pipe 1 in a concave-convex shape. That is, the inner surface of the steel pipe 1 is formed on the inner surface of the steel pipe 1 by the knurled portion 37 having diagonal lines intersecting in different directions, and the knurled portion 37 having concavo-convex shapes in FIG. 3(A) in the drawing. ), to form a rough groove in a substantially rhombus shape. In the drawings, the shape as shown in (A) of FIG. 3 may be formed by one processing, or may be formed by two processing.

In addition, the third frame 38 may be horizontally fixed to the upper end of the second frame 34 in the same manner as the horizontal bar 36 , and a cylinder for pressing the horizontal bar 36 on the lower surface of the third frame 38 . (39) can be installed. In the above, the cylinder 39 presses the horizontal bar 36 to an appropriate pressure, so that the depth of the groove portion (or the concave-convex groove) formed by the knurl portion 37 can be adjusted.

Next, the coupling relationship of the inner surface processing apparatus for steel pipe will be described in detail.

In the present invention, the inner surface processing apparatus for a steel pipe may be sized to sufficiently seat the steel pipe 1 to be processed, as shown in FIGS. 5 to 9 in the drawings, and the support plate 10 is approximately 16m in length and 3m in width. can be of any size.

In the above, a plurality of rails 11 may be fixed to the upper surface of the support plate 10 in the longitudinal direction, and these rails 11 may be divided and fixed by a predetermined length on both left and right sides in the longitudinal direction, respectively.

A rotating part 20 for rotating the steel pipe 1 may be installed between these rails 11, and the rotating part 20 comes into contact with the outer surface of the steel pipe 1 and rotates the steel pipe 1 with a plurality of rollers 21 ) and a driving motor 22 for rotating the roller 21 , and a support 33 may be installed on the bottom of the roller 31 to withstand the weight of the steel pipe 1 .

In the above, the roller 21 of the rotating part 20 may have a length longer than the length of the steel pipe 1 to be processed or the length of the steel pipe 1, and the roller 21 made of a pair of two is a gear, a chain, etc. It can be connected so that it can be rotated in the same direction by the power transmission means of

Also, on both sides of the support plate 10 , moving pressing parts 30 that can move to the inside of the steel pipe 1 may be installed, respectively. The moving pressing unit 30 moves toward the inside of the steel pipe 1 and uses the knurl holder 35 to draw the inner surface of the steel pipe 1 as shown in FIG. can build wealth.

The moving pressing unit 30 can install the wheels 31 to be movable along the bottom surface of the rail 11, and on the upper surface of the rail 11, the first frame ( 33) can be installed.

In addition, the second frame 34 can be vertically fixed to the upper surface of the first frame 33, and at a predetermined height of the second frame 34, a wrench holder ( 35) can be installed.

In the above, the knurl holder 35 can install a horizontal bar 36 horizontally on the second frame 34 , and a groove portion (concave-convex groove) is formed on the inner surface of the steel pipe 1 at the tip of the horizontal bar 36 . It is possible to provide a knurled portion 37 that can do this.

In the above, the knurl part 37 can be coupled to the horizontal bar 36 to be replaceable, and is rotatably coupled to the horizontal bar 36 through a bearing.

In addition, the third frame 38 can be fixed to the upper end of the second frame 34 in the same direction as the knurl holder 35 , and the horizontal bar of the knurl holder 35 is located on the bottom of the third frame 38 . A cylinder 39 for pressurizing (36) can be provided. In the above, the cylinder 39 may use hydraulic pressure or pneumatic pressure, but it is preferable to use hydraulic pressure to strongly press the horizontal bar 36 .

Meanwhile, as shown in FIGS. 10 to 11 in the drawings, a vibrator 36a may be installed in the inner surface processing apparatus for a steel pipe to more uniformly form the groove portion of the steel pipe, and the vibrator 36a is a horizontal bar 36. is installed in conjunction with

In the above, the vibrator 36a is disposed on the upper side of the horizontal bar 36 so as not to contact the steel pipe 1 and close to the knurled part 37, and is installed to be coupled to the horizontal bar 36 by a bracket 36b. , generate vibration in the vertical direction.

The vibrator 36a generates vibrations in the vertical direction, thereby vibrating the knurl portion 37 in the vertical direction, which is effective in forming the groove portion of the steel pipe more uniformly. Accordingly, it is possible to further improve the reliability of the coating material and the adhesion strength of the groove formed by pressure and vibration in the future.

In addition, the intake pipe 37a is horizontally disposed on the lower side of the horizontal bar 36 so as not to contact the steel pipe 1, and the intake pipe 37a is coupled to the horizontal bar 36 by a bracket 37c. , a plurality of intake holes (37b) are formed on the lower side of the end portion close to the knurl (37).

In the above, the intake pipe (37a) is formed with the length of the horizontal bar (36), is connected to the intake fan with a bellows hose from the outside of the inner surface processing device for steel pipe, and a plurality of intake holes (37b) are formed by the strong suction force of the intake fan. The metal powder and foreign substances are sucked through and discharged to the outside of the steel pipe (1).

Accordingly, the intake pipe 37a sucks in metal powder and foreign substances generated in the knurl processing operation and discharges it to the outside of the steel pipe 1, thereby preventing respiratory diseases of the worker and improving the working environment.

Next, a process of executing the step S20 will be described with reference to FIG. 9 in the drawings.

In the present invention, the processing method of the inner surface processing apparatus for a steel pipe includes the steps of pressing a cylinder to form a knurl holder to a desired depth, rotating a steel pipe seated on a rotating part, and a knurl holder in contact with the inner surface of the steel pipe horizontally moving the moving and pressing part along the rail, separating the knurl holder moved to the inside of the steel pipe to the outside of the steel pipe, and separating the steel pipe seated in the rotating part.

Each step in the above will be described in detail as follows.

First, the steel pipe (1) to be processed is seated on the rotating part (20), and in a state where the steel pipe (1) is stably seated on the rotating part (20), the knurl holder (35) of the moving pressing part (20) is moved to the steel pipe Adhere to the inner surface of (1).

In the close contact of the knurl holder 35, the knurl part 37 is in close contact with both ends of the steel pipe 1, respectively, and the height of the cylinder 39 installed in the third frame 38 is adjusted to provide an appropriate pressure. is pressurized to

That is, the pressing force of the cylinder 39 is adjusted according to the depth of the groove portion such as the groove portion (concave-convex groove) to be formed in the steel pipe 1 by the knurl portion 37 of the knurl holder 35 . This causes the horizontal bar 36 to be strongly pressed with the cylinder 39 when the depth of the groove is to be formed, and the horizontal bar 36 is lightly pressed with the cylinder 39 when the depth of the groove is to be formed thinner. do.

As described above, as the roller 21 is rotated by the driving motor 22 of the rotating unit 20 in a state in which the knurl holder 35 of the moving pressing unit 30 presses the inner surface of the steel pipe 1 , The steel pipe 1 is rotated.

That is, since the steel pipe 1 is in close contact between the roller 21 and the knurled holder 35, the steel pipe 1 rotates according to the rotation of the roller 21, and the rotation of the steel pipe 1 causes the furnace The grooves in the concave-convex shape are formed on the inner surface of the steel pipe 1 by the ratt 37 .

In addition, the wheel 31 is rotated by the motor 32 in the knurl holder 35 of the moving pressing unit 30 , and the wheel 31 moves in a straight line along the rail 11 . Accordingly, the moving pressing unit 30 is horizontally moved toward the inside of the steel pipe (1).

On the other hand, the moving pressing units 30 installed on both sides of the steel pipe 1 can move at the same speed at both ends of the steel pipe 1, and the moving pressing units 30 on one side are 1 of the entire length of the steel pipe 1 . While moving the /3 length, the moving pressing part 30 on the other side can be moved to 2/3 the length of the entire length of the steel pipe 1 .

In the above, the moving length of the moving pressing part 30 may be different, in order to better form the groove formed on the inner surface of the steel pipe 1 .

That is, when the two moving pressing units 30 come into contact with each other at the midpoint of the steel pipe 1 , the groove is not formed as much as the protruding length of the horizontal bar 36 fixing the knurled unit 37 , so the moving pressing unit is not formed. This is to vary the moving distance of the part 30 so that the same groove part is formed over the entire length of the steel pipe 1 .

As such, the surface area of the coating or coating is widened as the grooves in the concave-convex shape are formed on the inner surface of the steel pipe 1, and as the coating or coating is thicker and formed to a certain depth by the grooves, the steel pipe 1 is thinner. can be used for a long time.

In the above, as the formation of the groove in the inner surface of the steel pipe 1 is completed, the rotation of the rotating unit 20 is stopped, and the moving pressing unit 30 is rotated by the motor 32 to rotate the wheel 31 and the first frame ( 33) is retracted to separate the knurl holder 35 to the outside of the steel pipe 1 .

In this way, in the state in which the knurl holder 35 is separated, the steel pipe 1 seated on the rotating part 20 proceeds to step S30 to perform a shot blasting process. In the above, it is sufficient if the shot blasting process is performed in the same way as the normal process, so a detailed description thereof will be omitted.

Next, it proceeds to step (S40) to coat the inner surface of the steel pipe for water supply.

As shown in Figs. 12 to 13 in the drawings, the coating device 500 for the inside of a steel pipe applied in the present invention is a movable inner coating control unit for controlling the opening and closing of the coating material supply line in the steel pipe for water supply (P) and for reciprocating the coating equipment. 510, a high-pressure hose 511 for supplying a liquid epoxy coating material, and other necessary piping and wiring, and by attaching a final injection device 512, arrow reciprocating on the inner surface over the entire length of the steel pipe, coating can be performed An internal dedicated manipulator (Manipulator: (520)) is used as a basic structure. The spraying device 512 provided on the inner surface of the steel pipe uses a commercial spray gun when the diameter of the steel pipe is large, for example, 400 mm or more, but is not limited thereto.

On the other hand, in the drawing, the coating device 500 for the inside of the steel pipe as shown in FIG. 13 is different from the coating device for the inside of the steel pipe shown in FIG. 12 in that a spraying device 512 ′ fixed to the length of the steel pipe P is provided. to be. That is, in the drawing, a plurality of nozzle holes are provided in the spraying device 512 ′ shown in FIG. 13 in the drawing, and the steel pipe ( The inner coating of P) is completed.

In addition, in the drawings, the injection devices 512 and 512' of the coating device 500 for the inside of a steel pipe shown in FIGS. 12 to 13 are provided with a through hole in the center of the rotating means 100, and can be mounted through the through hole. .

On the other hand, in the drawings, in the structure shown in FIGS. 12 to 13, only the structure provided with the injection devices 512 and 512' has been described, but the present invention is not limited thereto. It is also possible to provide a structure that allows

In addition, in the drawings, the structure shown in FIGS. 12 to 13 has been described as a structure in which the liquid epoxy coating material is coated on the inside of the steel pipe P through the injection devices 512 and 512 ′, but is not limited thereto.

After that, when a triple coating layer is formed on the surface of the steel pipe (P) and the elvan solvent-free epoxy is coated on the inside of the steel pipe (P), the steel pipe is taken out from the coating device using a crane (not shown), The manufacturing process is completed.

In this embodiment of the present invention, the knurling process is first applied to the inner surface of the steel pipe, then the shot blasting process is performed, and after performing the first to third coating processes on the outer surface of the steel pipe in the subsequent process, the inner surface of the steel pipe is coated with a coating material Thus, by manufacturing a steel pipe for water supply, the adhesion and adhesion strength of the coating material are improved to further increase the durability of the steel pipe, while the long-term use of the steel pipe is possible and contamination of the water supply is prevented.

As a result, by first performing the knurling process on the inner surface of the steel pipe, the surface roughness of the inner surface of the steel pipe is increased, so the adhesion and adhesion strength of the coating material are improved to prevent the initial peeling of the coating layer, thereby further enhancing the durability of the steel pipe. Long-term use is possible.

The preferred embodiment of the present invention has been described with reference to the above, and it is not limited to the above embodiment, and a person of ordinary skill in the art to which the present invention belongs through the above embodiment does not deviate from the gist of the present invention It can be implemented with various changes in

10: base plate 11: rail
20: rotating part 21: roller
22: drive motor 23: support
30: moving pressing unit 31: wheel
32: motor 33: first frame
34: second frame 35: krollet holder
36: horizontal bar 36a: vibrator (vibrator)
36b: bracket 37: knurled part
37a: intake pipe 37b: intake hole
37c: bracket 38: third frame
39: cylinder 100: rotation means
500: coating device 511: high pressure hose
512 (512'): injector 520: manipulator
P: steel pipe

Claims (3)

(a) seating a steel pipe of a certain diameter on the rotating part 20; (b) processing the inner surface of the steel pipe seated on the rotating part 20 in the above step by knurling; (c) processing the shot blasting on the inner surface of the steel pipe knurled in the step; (d) heating the shot-blasted steel pipe in the above step, and first to third coating the outer surface of the steel pipe with a coating material; and (e) coating the inner surface of the steel pipe coated with the outer surface in the above step with a coating material;
The step (b) is carried out with an inner surface processing apparatus for a steel pipe, the inner surface processing apparatus for a steel pipe, a support plate 10 having a predetermined size and provided with a rail 11; a rotating part 20 rotatably installed on the upper surface of the support plate 10 by the operation of the driving motor 32; and a moving pressing unit 30 that is movably installed along the rail 11 while pressing the inner surface of the steel pipe 1 rotated by the rotating unit 20;
The rotating unit 20 includes a plurality of rollers 21 rotatably installed in the longitudinal direction on the upper surface of the support plate 10; a driving motor 22 for rotating the roller 21; Includes; support 23 for stably supporting the roller 21;
The moving pressing unit 30 includes a wheel 31 moving along the bottom surface of the rail 11 by rotation of the motor 32; a first frame 33 movably installed on the upper surface of the rail 11; a second frame (34) vertically fixed to the first frame (33); a knurl holder (35) fixed toward the inner surface of the steel pipe (1) at a predetermined height of the second frame (34); a third frame 38 horizontally fixed to an upper end of the second frame 34; A cylinder 39 installed under the third frame 38 and pressurizing the knurl holder 35; includes;
The knurl holder 35 is composed of a horizontal bar 36 having a predetermined length, and a knurled portion 37 coupled to the tip of the horizontal bar 36, and a vibrator 36a is attached to the horizontal bar 36. A method of manufacturing a steel pipe for water supply, characterized in that the coupling is installed while the intake pipe (37a) is coupled and installed.
According to claim 1,
The vibrator 36a,
A steel pipe for water supply, characterized in that it is disposed on the upper side of the horizontal bar (36) so as not to contact the steel pipe (1) and is close to the knurled part (37), and is coupled to the horizontal bar (36) by a bracket (36b). manufacturing method.
According to claim 1,
The intake pipe (37a) is,
It is arranged horizontally on the lower side of the horizontal bar 36 so as not to contact the steel pipe 1 , is coupled to the horizontal bar 36 by a bracket 37c, and is located at the lower side of the end close to the knurled part 37 . A method of manufacturing a steel pipe for water supply, characterized in that a plurality of intake holes (37b) are formed in the.

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