JP6680590B2 - Painting method, painting system and heating device - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a coating method, a coating system, and a heating device that are used when coating the outer surface of a metal tube.

  Since cast iron pipes used for water pipes and the like are buried in the ground, corrosion resistance to ground water and the like is required, and the outer surface of the cast iron pipe is anticorrosive coated. The outer coating of the outer surface of the cast iron pipe is performed after a preheating step of heating the cast iron pipe to a predetermined temperature necessary for coating, for example, 60 to 90 degrees before coating the outer surface of the cast iron pipe. This preheating step can be performed by immersing the cast iron pipe in hot water as shown in Patent Document 1, for example. In the preheating process by immersion in warm water, prepare a water tank of a size that can accommodate cast iron pipes, fill the water tank with water, heat the water in the water tank, and then insert the preheated cast iron pipes one after another. The tube is heated by heat transfer from warm water.

  Further, as a method other than hot water immersion in this preheating step, Patent Document 2 discloses that hot air blowing or infrared irradiation can be used as the preheating means. In the case of hot air blowing, a gas furnace capable of accommodating a cast iron pipe is prepared and heated by blowing hot air such as natural gas burned in the gas furnace. Further, in the infrared irradiation, the ambient temperature is raised by an infrared heater or the like, and the cast iron pipe is heated by heat conduction from the air around the cast iron pipe.

JP 2012-223695 A JP-A-8-141498

  Among the above-mentioned preheating means, for hot water immersion, in order to heat the cast iron pipe, it is necessary to first warm the water filled in the water tank from a low temperature state to a predetermined temperature (60 to 90 degrees). It takes a long time to heat up the water. Further, since it is necessary to first warm the water in the water tank or keep the hot water in the water tank at a predetermined temperature, a large amount of energy is used. Further, since a plurality of cast iron pipes are repeatedly immersed in the same hot water, the hot water may be contaminated by stains on the inner and outer surfaces of the cast iron pipe. Therefore, there is a possibility that stains will adhere to the cast iron pipe after soaking in warm water, and when removing the stain, it is necessary to wash the cast iron pipe.

  Further, a gas furnace that blows hot air needs to burn natural gas or the like, which consumes a large amount of energy and poses a problem associated with combustion and the generation of harmful substances such as CO and NOx. Preheating by infrared irradiation does not absorb infrared rays on the outer surface of the cast iron pipe, so the air around the cast iron pipe is heated by infrared irradiation, and the outer surface of the cast iron pipe is warmed by heat conduction from the surrounding air, which is energy efficient. bad.

  Therefore, in view of such a problem, the present invention eliminates the above-mentioned disadvantages, and when heating the outer surface of the metal tube before coating the outer surface of the metal tube, performs a safe and energy-efficient heating step. It is an object of the present invention to provide a coating method, a coating system, and a heating device that can be used.

  The coating method of the present invention is a coating method in which an outer surface is coated on the outer surface of a metal tube, wherein the coating method applies a base material capable of absorbing infrared rays to the outer surface of the metal tube before the outer surface coating. Pretreatment step to do, by irradiating the base material applied to the outer surface of the metal tube subjected to the pretreatment step with infrared rays, heating the base material, a heating step of heating the metal tube, An outer surface coating step of applying a water-based coating material on the heated base material.

  Further, the pretreatment step comprises a step of forming a metal sprayed coating on the surface of the metal tube, and a step of applying a water-based sealing agent on the surface of the metal sprayed coating, the base material, the metal It is preferable that the sealing treatment agent is applied to the surface of the thermal spray coating.

  Further, in the step of applying the sealing treatment agent, the water-based sealing treatment agent is applied, and in the heating step, the metal pipe is heated so that the temperature of the outer surface of the metal pipe becomes 60 to 90 degrees. Preferably.

  Further, the coating system of the present invention is a coating system for performing an outer surface coating on an outer surface of a metal tube, wherein the coating system is a base material capable of absorbing infrared rays on the outer surface of the metal tube before the outer surface coating. By applying infrared rays to the base material applied to the outer surface of the metal pipe by the pretreatment device, a heating device for heating the base material and heating the metal pipe, An outer surface coating device for coating a water-based coating material on the heated base material is provided.

  Further, the pretreatment device comprises a spraying device for forming a metal sprayed coating on the surface of the metal tube, and a sealing device for applying a water-based sealing treatment agent on the surface of the metal sprayed coating, wherein the base material is It is preferable that the sealing treatment agent is applied to the surface of the metal spray coating.

  Further, it is preferable that the water-based sealing agent is applied and the heating device is configured to heat the metal tube so that the temperature of the outer surface of the metal tube is 60 to 90 degrees.

  In addition, the heating device of the present invention is a pretreatment device that applies a base material capable of absorbing infrared rays to the outer surface of the metal pipe, and an introducing portion that introduces the metal pipe coated with the base material, and the base material is applied. By irradiating the metal tube with infrared rays to heat the base material, an infrared irradiation unit for heating the metal tube and an outer surface coating device for applying a water-based paint to the metal tube where the base material is heated. And a delivery unit for delivering the metal pipe.

  Further, the infrared irradiation unit, a heating furnace capable of accommodating a metal tube inside, a plurality of infrared irradiation panels provided in the heating furnace, and from the introduction unit into the heating furnace, and the heating furnace A transport device for transporting the metal pipe from inside to the delivery part, and a support device for supporting the metal pipe introduced into the heating furnace by the transport device, wherein the support device transports the metal pipe to the metal pipe. It is preferably configured to rotate about the axis of the tube.

  Further, the supporting device includes first and second supporting portions that support both ends of the metal pipe, and at least one of the first and second supporting portions faces an end surface of one end of the metal pipe. It is preferable to have a plate-shaped contact portion that can move forward and backward and that contacts the end surface of the one end of the metal pipe and supports the one end of the metal pipe.

  Further, it is preferable that the contact portion is made of silicon rubber.

  According to the coating method, the coating system, and the heating device of the present invention, it is possible to perform a safe and energy-efficient heating step when heating the outer surface of the metal tube before coating the outer surface of the metal tube.

It is a schematic block diagram of the coating system of one Embodiment of this invention. It is the figure seen from the end face side of the metal tube which shows the heating device of one embodiment of the present invention. It is a figure which shows a mode that a metal pipe is raised and lowered in the heating furnace of the heating apparatus of FIG. It is the schematic which shows the heating device of other embodiment of this invention. It is a figure which shows the support part in other embodiment of this invention. It is the sectional view on the AA line in FIG.

  Hereinafter, a coating method, a coating system, and a heating device of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an outline of a coating system S of the present invention. As shown in FIG. 1, the coating system S according to the present embodiment includes a pretreatment device 2 for applying an underlayer material capable of absorbing infrared rays to the outer surface of a metal tube before the outer surface coating, and a metal by the pretreatment device 2. A heating device 1 that heats the base material by heating the metal pipe by irradiating the base material applied to the outer surface of the pipe with infrared rays, and an outer surface coating device that applies a water-based paint onto the heated base material. 3 and 3.

  The pretreatment device 2 is a device that performs a treatment before coating the outer surface in a series of processes for coating the outer surface of the metal tube, and is provided on the upstream side of the heating device 1 as shown in FIG. 1. The pretreatment device 2 is configured to apply a base material capable of absorbing infrared rays before the infrared rays are irradiated by the heating device 1. The base material is applied to the outer surface of the metal tube in order to efficiently perform heating in the heating device 1. The base material is not particularly limited as long as it can absorb infrared rays and can be easily applied to the metal tube. As the base material, various paints can be used. For example, an aqueous paint that can be applied and dried at room temperature can be used. By using the water-based paint that can be applied and dried at room temperature, complicated processing in the pretreatment device 2 is unnecessary, and the process is simplified.

  In this embodiment, the pretreatment device 2 includes a thermal spraying device 21 and a sealing device 22 as shown in FIG. The thermal spraying device 21 forms a metallic thermal spray coating on the surface of the metal tube. The metal spray coating can be a Zn—Al-based pseudo-alloy layer in which a zinc layer and an aluminum alloy layer are mixed by metal spraying, for example, and can form an anticorrosion layer for a metal tube. The sealing device 22 applies and seals a sealing treatment agent into the pores of the metal spray coating formed by the spray device 21. The pores of the metal sprayed coating are blocked by the sealing device 22 to prevent the corrosion factor from reaching the surface of the metal tube. In this case, the pore-sealing agent applied by the pore-sealing device 22 serves as a base material that absorbs infrared rays emitted by the heating device 1. When the pore-sealing agent is used as the base material, the pore-sealing agent serves as a medium that absorbs infrared radiation from the heating device 1 and can further seal the pores of the metal sprayed coating. And the base material coating process before infrared irradiation can be performed simultaneously. As the pore-sealing agent, an aqueous pore-sealing agent, for example, an amorphous silica-based pore-sealing agent can be used. The water-based sealing agent can be applied to the surface of the metal tube at room temperature (no special heating is required after spraying), and an extra process is not required to apply the base material.

  The heating device 1 preheats the surface of the metal tube coated with the base material to a predetermined temperature necessary for coating, for example, 60 to 90 degrees, by infrared irradiation before performing the outer surface coating of the metal tube. As shown in FIG. 2, the heating device 1 of the present embodiment irradiates infrared rays to the introduction part 11 for introducing the metal pipe P coated with the base material and the metal pipe P coated with the base material. An infrared irradiation unit 12 that heats the base material to heat the metal pipe P, and a delivery unit 13 that delivers the metal pipe P toward the outer surface coating device 3.

  As shown in FIG. 2, the introduction unit 11 receives the metal pipe P coated with the base material from the pretreatment device 2 and introduces the metal pipe P into the infrared irradiation unit 12. In the present embodiment, as shown in FIG. 2, the introduction unit 11 includes a transfer device 11a that can move forward and backward toward the infrared irradiation unit 12 while supporting the metal tube P. The transfer device 11a is configured to move toward the transfer device 12a (conveyor) of the infrared irradiator 12 and move vertically in the vertical direction, and mounts the metal pipe P on the metal pipe support 12b on the transfer device 12a. Place.

  As shown in FIGS. 2 and 3, the infrared irradiation unit 12 includes a heating furnace 12c capable of accommodating a metal tube P therein, a plurality of infrared irradiation panels 12d provided in the heating furnace 12c, and an introduction unit. 11 and a transfer device 12a for transferring the metal pipe P from the heating furnace 12c to the delivery section 13 from the heating furnace 12c. The heating furnace 12c is configured to accommodate one or a plurality of metal tubes P in order to heat the metal tubes P in the heating furnace 12c. In the present embodiment, the three metal tubes P are housed in the heating furnace 12c, but the number of the metal tubes P housed in the heating furnace 12c is not particularly limited. As shown in FIG. 2, the transport device 12a is, for example, a conveyor having a plurality of metal pipe supporting portions 12b capable of supporting the metal pipe P, and the metal pipe P introduced from the introducing portion 11 by driving the conveyor. Is transported into the heating furnace 12c, and the metal pipe P, which has been heated, is transported toward the delivery unit 13.

  The infrared irradiation panel 12d irradiates infrared rays to heat the base material applied to the metal tube P, for example, to heat the outer circumference of the metal tube P to 60 to 90 degrees. More specifically, the infrared radiation panel 12d is a catalyst radiation panel, which radiates infrared rays by a reaction between the catalyst panel and natural gas, and at the same time, an air supply mechanism (not shown) provided in the infrared radiation unit 12. Hot air convection is generated in the heating furnace 12c. The wavelength of infrared rays radiated from the infrared radiating panel 12d is, for example, 2 to 10 μm, and since the metal tube P has a base material applied to the outer surface thereof before entering the heating device 1, the base material has infrared rays in this wavelength range. Are absorbed, the molecular motion of the base material is excited, and the base material is heated. In the present embodiment, as shown in FIG. 2, the infrared irradiation panel 12d has an inverted V-shape in a cross section perpendicular to the axial direction of the metal pipe P, in which a pair of infrared irradiation panels 12d are provided above the metal pipe P. A plurality of (nine in FIG. 3) are provided in the axial direction of the metal pipe P as shown in FIG. However, the infrared irradiation panel 12d is not limited in shape and number as long as it can irradiate the base material of the metal tube P with infrared rays.

  Further, in the present embodiment, as shown in FIG. 3, a supporting device 12e for supporting the metal pipe P introduced into the heating furnace 12c by the carrying device 12a during infrared heating is provided. In the present embodiment, the support device 12e can be moved up and down in order to move the metal pipe P from above the transport device 12a toward the infrared irradiation panel 12d and to move the metal pipe P toward the transport device 12a after infrared irradiation. It is configured. In the present embodiment, as shown in FIG. 3, the supporting device 12e moves up and down the first and second supporting portions Su1 and Su2 that support both ends of the metal tube P and the first and second supporting portions Su1 and Su2. An elevating part U for driving and a driving part D for driving the first and second supporting parts Su1, Su2 in the axial direction and around the axis are provided. In the present embodiment, as shown in FIG. 3, the first and second support parts Su1 and Su2 are partially inserted into openings formed at both ends (reception port, insertion port) of the metal pipe P, and Support the tube P. In the present embodiment, the first and second support parts Su1 and Su2 are formed in a substantially truncated cone shape, but the shapes of the first and second support parts Su1 and Su2 are not particularly limited. In the present embodiment, by driving the driving unit D, as shown by the chain double-dashed line in FIG. 3, when the first and second supporting units Su1 and Su2 move in the axial direction of the metal pipe P toward the opening, The side surfaces of the first and second support parts Su1 and Su2 contact the opening edges of the openings of the metal pipe P, the first and second support parts Su1 and Su2 support and lift the metal pipe P, and the metal The pipe P is rotated around the axis of the metal pipe P. As a result, infrared rays are uniformly irradiated on the outer circumference of the metal tube P. Note that the support device 12e may raise and lower the metal pipe P by another mechanism without providing a raising and lowering mechanism such as the raising and lowering unit U as described later.

  As shown in FIG. 2, the delivery unit 13 delivers the heated metal tube P from the heating furnace 12c to the outer surface coating apparatus 3. In the present embodiment, as shown in FIG. 2, the delivery unit 13 has a structure basically similar to that of the introduction unit 11, and is a transfer device that can move forward and backward toward the infrared irradiation unit 12 and the outer surface coating device 3. 13a is provided. The transfer device 13a is configured to move toward the transfer device 12a (conveyor) of the infrared irradiation unit 12 and to be vertically movable in the vertical direction, and takes out the metal pipe P from the metal pipe support portion 12b on the transfer device 12a. .

  The outer surface coating device 3 is a device for coating the outer surface (on the base material) of the heated metal pipe P. A publicly known coating device can be used as the outer surface coating device 3, and thus details thereof will be omitted. In the outer surface coating device 3, a water-based paint is applied onto the heated base material by a coating means such as a spray gun. As the water-based paint, for example, a synthetic resin paint specified in JWWA K 139 “Ductile iron pipe synthetic resin paint for water supply” of the Japan Water Works Association standard can be used. The outer surface coating applied by the outer surface coating device 3 may be applied a plurality of times, for example, after the first coating, then the second coating.

  Next, the coating method of this embodiment will be described. The coating method described below is merely an example, and the coating method of the present invention is not limited to the following embodiments.

  First, the metal pipe P whose outer surface is not coated is moved to the pretreatment device 2, and a base material capable of absorbing infrared rays is applied to the outer surface of the metal pipe P (pretreatment step). In the pretreatment process, the base material is applied by the pretreatment device 2 so that the metal tube P can absorb the infrared rays emitted from the infrared ray irradiation section 12 of the heating device 1. The pretreatment step includes a step of forming a metal sprayed coating on the surface of the metal pipe by the spraying device 21, and a step of applying a water-based sealing agent on the surface of the metal sprayed coating by the sealing device 22. In this case, the application of the base material and the sealing treatment can be simultaneously performed, and the corrosion resistance and the energy efficiency at the time of heating can be simultaneously improved. In the pretreatment step, when the step of applying the pore-sealing agent is performed, the pore-sealing agent can be heated while being dried in the subsequent heating step. Therefore, it is not always necessary to preheat the metal tube P before applying the sealing agent, and an extra process for applying the base material can be omitted.

  When the pretreatment process is completed, the metal pipe P coated with the base material is transferred from the pretreatment device 2 to the heating device 1. The metal pipe P coated with the base material is placed on the transfer device 11a of the introduction part 11, and then the transfer device 11a is driven to be placed on the metal pipe support part 12b of the transfer device 12a. The metal tubes P placed on the transfer device 12a are sequentially fed into the heating furnace 12c. After the metal pipe P sent into the heating furnace 12c is driven by the drive unit D of the supporting device 12e and the openings at both ends of the metal pipe P are supported by the first and second support units Su1 and Su2, The ascending / descending unit U ascends toward the infrared irradiation panel 12d. When the metal tube P is in the raised position, the metal tube P is irradiated with infrared rays by the infrared irradiation panel 12d in the heating furnace 12c. When the infrared rays are radiated toward the metal tube P, the base material on the surface of the metal tube P applied in the pretreatment step absorbs the infrared rays and the base material is heated. Here, the irradiation of infrared rays is not simply used to raise the ambient temperature around the metal tube P, but can excite the molecular motion of the base material to directly heat the surface of the metal tube P. . Therefore, it is possible to raise the surface temperature of the metal pipe P more quickly than heating by heat conduction from the ambient temperature. Therefore, the amount of energy consumed per metal pipe P can be reduced, the energy efficiency can be improved, and the heating process time can be shortened. Further, in the present embodiment, the infrared ray irradiation excites the molecular motion of the base material, and the convection of air in the heating furnace 12c further accelerates the heating of the metal tube P.

  When the surface temperature of the metal pipe P rises to 60 to 90 degrees by the heating process, the metal pipe P is transferred from the heating furnace 12c to the transfer device 13a of the delivery unit 13 by the transfer device 12a. The metal pipe P transferred to the transfer device 13 a is then transferred to the outer surface coating device 3. In the outer surface coating process in the outer surface coating apparatus 3, synthetic resin coating (primary coating, secondary coating, etc.) is applied to the metal pipe P whose surface temperature has been raised to 60 to 90 degrees. The inner surface of the metal tube P can be coated before or after the series of steps described above.

  As described above, according to the coating method of the above-described embodiment, the heating step is performed by infrared irradiation, and the risk of dirt adhering to the metal pipe as in hot water immersion is low. In addition, the amount of energy used is small as compared with the heating process using hot water immersion or a gas furnace. Further, according to the coating method of the above embodiment, since no flame is used, it is safe and it is possible to reduce the emission of harmful substances such as CO and NOx. Further, since the base material capable of absorbing infrared rays is applied in advance in the pretreatment step, the molecular motion of the base material irradiated with infrared rays is excited, and the metal tube can be heated quickly. Also, unlike the conventional heating method that relies on heat conduction from the atmosphere by heating the ambient temperature, the base material on the outer surface of the metal tube is heated. Compared with the energy saving effect. Further, when the base material on the outer surface of the metal pipe is heated, the temperature of the inner surface of the metal pipe does not rise so much as compared with the outer surface, so that the resin coat (for example, the mortar on the inner surface of the metal pipe is coated on the inner surface of the metal pipe. It is possible to prevent deterioration of the resin coating applied to the inner surface such as the lining.

  Next, a heating device according to another embodiment will be described with reference to FIGS. 4 to 6. The heating device of the present embodiment can be used in the above-described coating method and coating system, like the heating device of the above-described embodiment. The coating method and the coating system using the heating device of the present embodiment are basically the same as those of the above-described embodiment, and therefore the description thereof will be omitted. Hereinafter, the description of the common points with the heating device of the embodiment described with reference to FIGS. 1 to 3 will be basically omitted, and the different points will be mainly described.

  As shown in FIG. 4, in the heating device 100 of the present embodiment, as in the above-described embodiment, the metal pipe P coated with the base material capable of absorbing infrared rays is introduced by the pretreatment device 2 and heated. The apparatus 100 irradiates the metal pipe P with infrared rays and heats the metal pipe P through the base material. The heating device 100 includes an infrared irradiation unit 12, and the infrared irradiation unit 12 includes a heating furnace 12c, a plurality of infrared irradiation panels 12d, a transfer device 12a (not shown in FIG. 4), and a transfer device. And a supporting device 12e for supporting the metal pipe P introduced into the heating furnace 12c by 12a. As shown in FIG. 4, the support device 12e includes first and second support parts Su1 and Su2 that support both ends of the metal tube P. In the present embodiment, the first support part Su1 is provided on the receiving port P1 side of the metal pipe P, and the second support part Su2 is provided on the insertion port P2 side. With the first supporting part Su1 and the second supporting part Su2, It is configured to support the metal pipe P by sandwiching the metal pipe P in the axial direction.

  In this embodiment, as shown in FIG. 4, at least one of the first and second support parts Su1 and Su2 (the second support part Su2 in this embodiment) is connected to one end of the metal pipe P (this embodiment). In the form, it has a plate-shaped contact portion C that can move forward and backward toward the end face of the insertion port P2) and that contacts the one end face of the metal pipe P and supports the one end of the metal pipe P. .

  The contact portion C is configured such that the end surface of the metal tube P (for example, the end surface of the insertion port P2) contacts the surface thereof. The material of the contact portion C is not particularly limited, but the contact portion C is formed of an elastic material such as rubber or synthetic resin having elasticity so as to serve as a cushioning material when the end surface of the metal pipe P is contacted. It is preferable that it is formed of silicon rubber. When an elastic material is used for the contact portion C, the contact portion C elastically deforms when contacted with the metal pipe P and slightly dents to absorb impact and prevent damage or damage to the end surface of the metal pipe P. can do. Further, when silicon rubber is used as the contact portion C, it not only functions as a cushioning material when the end surface of the metal tube P is contacted, but also has low reactivity with infrared rays when irradiated with infrared rays and has high heat resistance. Since the cost is high, the life of the contact portion C can be extended.

  In the present embodiment, the contact portion C is formed in a disk shape having a diameter larger than the outer diameter of the metal pipe P as shown in FIG. The size and shape are not particularly limited as long as they can come into contact with each other.

  In the present embodiment, as shown in FIG. 6, the contact portion C is attached to the base portion B to which the contact portion C is attachable / detachable, by a fixing means such as a bolt. The base portion B is connected to the drive portion D, and the base portion B and the contact portion C are configured to move forward and backward in the axial direction of the metal pipe P and to be rotatable around the axis of the metal pipe P. In addition, in the present embodiment, as shown in FIGS. 5 and 6, the second support portion Su2 includes a drop-out prevention portion F that prevents the metal pipe P from falling off when it is supported. As shown in FIGS. 5 and 6, the fall-out prevention portion F has a fall-out prevention member Fa that is provided on the outer peripheral side of the base portion B and is arranged at a position projecting from the surface of the contact portion C. In the present embodiment, the fall prevention body Fa is sandwiched between the contact portion C and a fixing member Fb provided on the outer peripheral side of the base portion B. In the present embodiment, the fall prevention body Fa is provided as a separate body from the contact portion C, but the fall prevention body Fa may be integrally formed with the contact portion C. In addition, in the present embodiment, the falling prevention body Fa is formed as a fan-shaped block body in which a portion facing the outer periphery of the metal pipe P is formed along the outer periphery of the metal pipe P, but Other shapes may be used as long as it is possible to prevent the pipe P from falling off.

  In the present embodiment, as shown in FIG. 5, a plurality of the fall prevention bodies Fa are provided in the circumferential direction of the contact portion C so as to be spaced apart from each other (three at equal intervals in the present embodiment), and the metal pipe P is rotated. Even if the metal pipe P is about to fall off, the metal pipe P can be prevented from coming off by coming into contact with the metal pipe P. The material of the fall prevention body Fa is not particularly limited, and the same material as the contact portion C can be used.

  As described above, in the present embodiment, the support portion Su2 that supports the metal pipe P has the plate-shaped contact portion C that supports the one end of the metal pipe P by supporting the end face of the one end of the metal pipe P. Since it has, the contact portion C contacts the end surface of the metal tube P to support the metal tube P, and does not contact the inner surface of the metal tube P. Therefore, for example, when a lining layer such as cement mortar lining is formed on the inner surface of the metal pipe P, the support portion Su2 does not contact the inner surface of the metal pipe P, and thus the lining layer on the inner surface of the metal pipe P is not formed. It is possible to prevent damage and scratches. In the present embodiment, the first support portion Su1 inserted into the inner surface side of the metal tube P is used on the receiving port P1 side of the metal tube P, and the plate-shaped contact with the insertion port P2 side of the metal tube P is performed. The second support portion Su2 having the portion C is used. When connecting a plurality of metal pipes P, the insertion port P2 of another metal pipe is inserted inside the receiving port P1 on the receiving port P1 side of the metal pipe P, and a lining layer such as cement mortar lining is not formed. Therefore, even if the first support portion Su1 inserted into the inner surface of the metal pipe P is used, the performance of the metal pipe P is not affected. However, the present embodiment shown in FIG. 4 is merely an example, and a supporting portion having plate-shaped contact portions C on both sides of the receiving port P1 and the insertion port P2 of the metal tube P may be used.

  Further, when the contact portion C is formed of silicon rubber, the contact portion C is less likely to be deteriorated by the infrared ray when heating using infrared rays as in the present embodiment, and the inside of the heating furnace 12c is Also strong against heat. Therefore, the life of the support portion can be extended, and the running cost of the entire device can be reduced.

1, 100 Heating device 11 Introductory part 11a Transfer device 12 Infrared irradiation part 12a Conveying device 12b Metal tube support part 12c Heating furnace 12d Infrared irradiation panel 12e Support device 13 Sending part 13a Transfer device 2 Pretreatment device 21 Thermal spraying device 22 Sealing device 3 External coating device B Base part C Abutment part D Drive part F Fall-out prevention part Fa Fall-out prevention body Fb Fixing member P Metal tube P1 Receptacle P2 Insertion port S Coating system Su1 1st support part Su2 2nd support part U Lifting part

Claims (7)

A coating method for coating the outer surface of a metal pipe, wherein the coating method comprises:
Forming a metal spray coating on the outer surface of the metal tube;
Applying a water-based sealing agent capable of absorbing infrared rays to the surface of the metal spray coating ,
By irradiating infrared rays to the aqueous sealing treatment agent coated on the outer surface of the front Kikin genus tube, a heating step of heating the aqueous sealing treatment agent, pre-heating the surface of said metal tube,
An outer surface coating step of applying a water-based paint on the water- based sealing agent on the surface of the metal tube which has been preheated . Before Symbol heating step, the method of coating according to claim 1, wherein said metal tube so that the temperature is 60 to 90 ° C. of the outer surface of the metal tube is heated. A coating system for coating the outer surface of a metal pipe, the coating system comprising:
A spraying device that forms a metal sprayed coating on the outer surface of the metal tube, and a pretreatment device that includes a sealing device that applies a water-based sealing treatment agent capable of absorbing infrared rays to the surface of the metal sprayed coating ,
By irradiating the water-based sealing treatment agent applied to the outer surface of the metal pipe by the pretreatment device with infrared rays, the water-based sealing treatment agent is heated, and a heating device for preheating the surface of the metal pipe,
A coating system comprising: an external coating device for coating a water-based paint on the water- based sealing agent on the surface of the preheated metal pipe . Before SL heating device, coating system of claim 3, wherein configured such that the temperature of the outer surface of the metal tube to heat the metal pipe so that 60 to 90 ° C.. From a pretreatment device that applies a water-based sealing treatment agent capable of absorbing infrared rays to the outer surface of the metal pipe, an introduction unit that introduces the metal pipe coated with the water-based sealing treatment agent ,
By irradiating the metal pipe coated with the water-based sealing agent with infrared rays, the water-based sealing agent is heated, and an infrared irradiation unit for preheating the surface of the metal tube,
A delivery unit for delivering the metal pipe to an outer surface coating device that heats the water-based sealing agent to apply a water-based paint to the metal pipe whose surface is preheated ,
The infrared irradiation unit,
A heating furnace that can accommodate a metal tube inside,
A plurality of infrared irradiation panels provided in the heating furnace,
A carrying device for carrying the metal pipe from the introduction part into the heating furnace, and from the heating furnace to the delivery part,
A supporting device for supporting the metal pipe introduced into the heating furnace by the transfer device,
The supporting device is configured such that the metal tube is rotated around the axis of the metal tube, and infrared rays from the infrared irradiation panel are uniformly irradiated to the outer periphery of the metal tube,
Heating device. The support device includes first and second support parts that support both ends of the metal tube,
At least one of the first and second support portions is movable forward and backward toward the end face of the one end of the metal pipe, and is in contact with the end face of the one end of the metal pipe to contact the one end of the metal pipe. The heating device according to claim 5 , wherein the heating device has a plate-shaped abutting portion that supports the. The heating device according to claim 6 , wherein the contact portion is made of silicon rubber.

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