JP2017124391A - Coating-recoating method of steel member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recoat coating from above its rust-preventive layer, and to recoat the coating by separately peeling the rust-preventive layer and an outer coating layer, by leaving the rust-preventive layer, when recoating the coating.SOLUTION: A first coating-recoating method of the present invention is a method for recoating coating by coating new paint on a remaining existing rust-preventive layer by peeling an outer coating layer in a sheet state by leaving the rust-preventive layer by softening a coating film by its heat by heating a steel member surface by induction heating. A second coating-recoating method of the present invention is a method for recoating the coating by coating new paint on the outside of its newly formed rust-preventive layer by forming the rust-preventive layer by coating a rust-preventive material on an exposed steel member by cutting and removing the remaining rust-preventive layer by a mechanical apparatus by peeling the outer coating layer in the sheet state by leaving the rust-preventive layer by softening the coating film by its heat by heating the steel member surface by the induction heating.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a paint repainting method in which an existing coating film applied to the surface of a steel member is peeled off and then painted again. In the present invention, the steel member is a steel structure such as a bridge, an elevated road, a building such as a power transmission tower or a radio tower, a steel product used or used in such a steel structure, various steel components, and other steel parts. Various steel materials in the field.

  The surface of the steel member used for the main girder of the bridge, the auxiliary steel material, etc. is painted. The coating system used for bridges, etc. is C-based coating using A- and B-based coatings that use red lead or lead-based rust-preventing coatings for rust prevention, and inorganic zinc rich paint (hereinafter referred to as “inorganic zinc”) for rust-preventing. It is divided roughly into. Conventionally, the A system paint and the B system paint have been adopted as the paint system of many steel bridges, but the C system paint is adopted as the paint system of most steel bridges at present. Such designations as A system paint, B system paint, and C system paint are described in a standard called “steel road bridge anticorrosion handbook” by the Japan Road Association.

  In the C-based coating, as shown in FIG. 7 (a), an inorganic zinc for rust prevention is applied to the surface of the blasted steel member X, and a mist-like mist coat is sprayed from the outside (top) thereof to form an inorganic zinc. The air hole inside is filled and the rust prevention layer 1 is formed. On the outside of the mist coat, an outer coating layer (coating film) 2 made of an epoxy resin, a fluororesin, a polyurethane resin or the like is formed.

  On the other hand, in the A system coating and the B system coating, as shown in FIG. 7 (b), an etching primer is applied to the surface of the blasted steel member X, and a lead or lead system is applied to the outside (upper) of the etching primer. Rust prevention paint is applied to form a rust prevention layer 1. The outer coating layer 2 is formed by applying a resin coating such as a phthalic acid resin coating on the outside of the red lead or lead-based antirust paint.

  By the way, since the coating of steel structures is corroded and deteriorated due to various factors such as wind and rain and ultraviolet rays, it is necessary to repaint regularly. Also, when red lead is used as a rust preventive material, such as A series paint and B series paint, it is preferable to remove all paint on the surface of steel members, but in the case of C series paint In addition, since the inorganic zinc of the rust-preventing layer exhibits a sacrificial anticorrosive action, it is considered that it is preferable to repaint with the rust-preventing layer remaining as long as it is healthy.

  When removing all the paint, if it is left as it is, new rust will be generated on the exposed surface from which the paint has been peeled off, so the exposed steel member must be subjected to rust prevention within 4 hours, increasing the work process. From the viewpoint of increasing work costs and material costs, etc., if the rust-preventing layer is not harmful and the rust-preventing layer is not harmful as in the case of C-based paint, it is necessary to leave the paint as far as possible. It is desirable to keep it.

  Conventionally, as a method of peeling off the coating on the surface of a steel structure, a method of scraping the surface using a mechanical instrument such as a grinder, a sander or a cup brush (Patent Document 1), or a chemical method of applying a release agent (Patent Document) 2) A method of peeling by induction heating by electromagnetic induction heating (Patent Documents 3 and 4), a method of scraping the coating by sandblasting, and the like have been proposed.

JP 2011-056333 A Japanese Patent No. 3985966 US Pat. No. 7,857,914 JP 2014-014933 A

  When C-based coating is employed, it is preferable to leave a rust-preventing layer. However, in the construction method in which the surface is cut using the mechanical device, it is difficult to cut the coating while leaving only the rust-preventing layer. In addition to the time and cost required for equipment for preventing scattering of cutting powder, various problems such as deterioration of working environment and noise due to scattering of cutting powder and the like occur. The chemical treatment method that removes the paint by applying a release agent does not activate the chemical reaction unless the temperature rises to 20 ° C or higher, and it takes a long time to activate. There are harmful effects such as. In addition, since the conventional high frequency induction heating device is so heavy that it must be lifted by a winch, there is a disadvantage that it is not easy to use. The blasting method requires equipment to prevent cutting powder from being scattered, requires large equipment, and requires advanced dust countermeasures for workers. In the supply environment, a large wind load acts to seal the work scaffold. There are difficulties such as.

  When A-based coating or B-based coating is used, both the rust-preventing layer and the outer coating layer to be peeled are treated as industrial waste, but both are coated with a coating containing, for example, PCB (polychlorinated biphenyl). If it is contained in a layer, it is necessary to deal with it by changing its processing method. Therefore, it is preferable to separate and dispose of both when disposing. In this regard, it is difficult to separate and cut the two with the machine tool, and the chemical treatment method, the induction heating method, and the blasting method have the above-described disadvantages.

  The problem to be solved by the present invention is that when repainting the steel member, only the outer coating layer is peeled off leaving the rust prevention layer, and a new paint (new paint) is repainted on the remaining rust prevention layer. Is to provide. In addition, a part of the remaining rust prevention layer in the thickness direction (surface layer side) is cut and removed to leave the deep layer side in the thickness direction (deep layer part), or all of the remaining rust prevention layer (from the surface layer side to the deep layer part) The steel member surface is exposed by cutting off, and a new rust inhibitor (new rust inhibitor) is applied to the remaining deep layer or exposed steel member exposed surface, and a new paint (new paint) is applied to the new rust inhibitor. Is to provide a paint repainting method for steel members

  The first paint repainting method of the present invention is a steel member paint repainting method provided with a rust-preventing layer and an outer coating layer (coating film) on the surface of the steel member, and the steel member surface is heated by induction heating with an induction heating device. The coating film is softened by the heat, and the outer coating layer is peeled off in a sheet state or solidified state without scattering, leaving a rust prevention layer, and a new paint on the existing rust prevention layer remaining on the steel member surface It is a method of repainting steel members by applying (new paint).

  Similar to the first paint repainting method, the second paint repainting method of the present invention heats the steel member surface by induction heating with an induction heating device, softens the coating film with the heat, and leaves the rust prevention layer. The coating layer is peeled off in a sheet state, and a part of the rust prevention layer in the thickness direction (surface layer side) left on the surface of the steel member is cut off to leave a deep layer portion in the thickness direction of the rust prevention layer, or the rust prevention layer Rust-proofing effect on the remaining rust-preventing layer left by cutting and removing everything from the surface layer side to the deep layer in the thickness direction, or on the exposed steel member exposed by cutting and removing everything A new antirust material is applied to form a new antirust layer (new antirust layer), and a new paint (new paint) is applied to the new antirust layer to form a new top coat. It is a construction method. In this case, a new rust-proof material and a new rust-proof material applied on it are formed by applying a new rust-proof material mainly composed of zinc (Zn), which has a higher ionization tendency than steel (Fe). Sacrificial anticorrosive action due to electrochemical action with the paint can be obtained.

The first paint repainting method of the present invention has the following effects.
(1) Since the existing rust preventive layer left on the steel material surface can be reused, the construction speed can be greatly reduced and the cost required for repainting can be suppressed.
(2) Since the outer coating layer is peeled off in a sheet state or in a solidified state without scattering, the paint containing harmful substances is not scattered as dust and the working environment is not deteriorated.
(3) Since the existing rust preventive layer on the steel surface is left, the amount of industrial waste can be reduced.
(4) Since only the induction heating device needs to be applied to the steel member, differences due to the experience and skill of the operator are unlikely to occur.
(5) Since the rust-preventing layer and the outer coating layer can be separated and peeled off, the coating film containing PCB in the outer coating layer can be disposed of safely and in a minimum amount, and industrial waste such as generation of PCB and dioxin. It is possible to reduce the adverse effects on the environment due to the material treatment.

The second paint repainting method of the present invention has the following effects.
(1) Since the outer coating layer is peeled off in a sheet state or in a solidified state without scattering, the paint containing harmful substances is not scattered as dust and the working environment is not deteriorated.
(2) Since the rust-preventing layer and the outer coating layer can be separated and peeled off, the coating film containing PCB in the outer coating layer can be disposed of safely and in a minimum amount, and industrial waste such as generation of PCB and dioxin It is possible to reduce the adverse effects on the environment due to the material treatment.
(3) Since the induction heating device only needs to be applied to the steel member, differences due to the experience and skill of the operator are unlikely to occur.
(4) By applying a new rust-preventing material containing zinc, which has a high ionization tendency, to the new rust-preventing material, the electrochemical sacrificial anti-corrosion action caused by the contact between the new rust-preventing material and the new paint on it is Rust prevention effect is obtained.

The flowchart which shows an example of the 1st painting repainting construction method of this invention. The flowchart which shows an example of the 2nd painting repainting method of this invention. The perspective view which shows an example of the high frequency induction heating apparatus used for the paint repainting method of this invention. (A) is explanatory drawing of the connection part of a head and a current transformer (CT), (b) is explanatory drawing of a coil electrode. Explanatory drawing of the flow of the refrigerant | coolant of a high frequency induction heating apparatus. Explanatory drawing in the case of implementing the paint repainting method of this invention using the high frequency induction heating apparatus of FIG. (A) is a schematic explanatory diagram of C-based coating using inorganic zinc as a rust-proof material, and (b) is a schematic explanatory diagram of A-based coating using lead red as a rust-proof material. An enlarged cross-sectional photograph of C-based paint using inorganic zinc as a rust-proof material

(Embodiment 1)
A first paint repainting method (hereinafter referred to as “repainting method”) of the present invention will be described with reference to the drawings. As shown in FIG. 1, the repainting method of this embodiment heats the surface of the steel member X by induction heating of the induction heating device 10 addressed to the outside of the steel member X, and paints the surface of the steel member X. Among them, a softening step S1 for softening the outer coating layer 2 outside the rust prevention layer 1, a peeling step S2 for peeling the softened outer coating layer 2 as a sheet-like lump (in a sheet state) from the rust prevention layer 1 by a peeling means, This is provided with a repainting step S3 in which a new paint is applied to the rust prevention layer 1 exposed by the peeling of the outer coating layer 2 to repaint the steel member X. In the present invention, a high-frequency induction heating device (IH) is suitable for the induction heating device, but a low-frequency induction heating device can be used if possible. Below, the case where a high frequency induction heating apparatus is used is demonstrated as an example. The cooling unit in the wave induction heating device of the present invention may be any of water cooling type, air cooling type and other cooling methods, but the case of the water cooling type will be described below as an example. The steel member X of the present application includes, for example, a main girder of a bridge. For convenience of explanation, an outline of the coating system of this embodiment will be explained prior to explanation of each process.

[Coating system]
The coating system of this embodiment is a C-based coating in which inorganic zinc is used as a rust preventive material. In this coating system, as shown in FIG. 7A, inorganic zinc (inorganic zinc rich primer, inorganic zinc rich paint, etc.) is applied as a rust preventive material to the surface (blast surface) of the blasted steel member X, A mist-like mist coat is sprayed from the outside to fill the air holes in the inorganic zinc, and the rust prevention layer 1 is formed. An epoxy resin is coated on the outside of the mist coat, and a fluorine resin or a polyurethane resin is overcoated on the outside of the epoxy resin to form the outer coating layer 2. The outer coating layer 2 is an example, and the structure of the outer coating layer 2 may be other than this.

[Softening process]
In the softening step S1, the surface of the steel member X is heated by induction heating of a high-frequency induction heating device (hereinafter referred to as “induction heating device”) 10 and the outer coating of the rust preventive layer 1 outside of the coating of the steel member X surface is performed. In this step, the layer 2 is softened. Through this step, the outer coating layer 2 is separated (raised) from the rust prevention layer 1. The induction heating device 10 is assigned to the outside of the steel member X, an AC power supply is supplied to the induction heating device 10, and the surface of the steel member X is heated by induction heating. The induction heating device 10 is moved along the steel member X while maintaining this state. It is preferable that the moving speed of the induction heating device 10 is a speed at which a place to be heated stays for about 1 to 2 seconds. The heating temperature of the surface of the steel material to be peeled off is suitably 100 ° C. or higher and lower than 250 ° C., particularly about 150 ° C. to 200 ° C. If the heating temperature exceeds 250 ° C., harmful components may be generated from the coating due to overheating, and if it is less than 100 ° C., the coating may be incompletely separated due to insufficient heating. However, these numerical values are merely examples, and optimum conditions may be selected according to various conditions such as the type of coating, the atmospheric temperature, the humidity, and the weather. As the induction heating device 10, an existing one can be used.

  The reason why the rust preventive layer 1 is not separated from the steel member X and only the outer coat layer 2 is separated from the rust preventive layer 1 is as follows. (1) The steel member X and the rust preventive layer 1 may be metal-based and are externally coated. Compared to the material of layer 2, the coefficient of linear expansion is low and difficult to extend, whereas the coefficient of linear expansion of outer coating layer 2 is high and easy to extend, (2) the coating of outer coating layer 2 is elongated and deteriorated by heating, (3) Since the surface of the steel member X is blasted, as shown in FIG. 8, the surface of the steel member X has mechanically fine irregularities, and there is a rust preventive material (inorganic zinc or a red lead described later. (The same) is also finely unevenly adhered (4) It is conceivable that the reasons of (1), (2) and (3) are combined.

The difference in linear expansion coefficient (1) will be described. For example, the linear expansion coefficient of iron (steel member) and inorganic zinc is about 120 × 10 ⁻⁵ , and the linear expansion coefficient of resin (outer coating layer) is 800 × 10. is about ^-5, the linear expansion coefficient of the two differ greatly. For this reason, a difference arises in the interface of inorganic zinc and resin (outer coating layer), and when the surface of steel member X is heated with induction heating device 10, rust prevention layer 1 does not separate from steel member X, but outer coating layer 2 It is considered that only the rust preventive layer 1 is separated.

  When the point of deterioration of the outer coating layer 2 due to the heating of (2) is described, when the steel member X is heated by the induction heating device 10 and the outer coating layer 2 on the surface side is heated, the coating is softened. Deterioration occurs. On the other hand, the heating temperature in the induction heating device 10 is equal to or lower than the heat resistance temperature of the steel member X, and the deterioration of the inorganic zinc mainly composed of the steel member X and zinc does not occur. As a result, it is considered that the inorganic zinc is not separated while being fixed to the steel member X, and only the outer coating layer 2 on which the deterioration has occurred is separated from the rust preventive layer 1.

  The adhesion between the steel member X and the anticorrosive material (3) will be described. The surface of the steel member X is blasted and roughened as shown in FIGS. Therefore, it is considered that the rust preventive material is easily mechanically adhered as compared with the case of applying to a smooth surface.

[Peeling process]
The peeling step S2 is a step of peeling the outer coating layer 2 softened by the softening step from the rust-preventing layer 1 with an existing kawaski or scraper. The outer coating layer 2 is in a state of being softened and separated from the rust preventive layer 1 in the softening step S1, and can be peeled off in a sheet state or a solidified state without being scattered by kawasuki or the like. However, since some coating remains on the surface of the rust-preventing layer 1 after peeling, it is desirable to scrape the remaining coating with Kawasuki or the like. The paint of the peeled or scraped outer coating layer is collected (outer coating layer collecting step: S2a in FIG. 1).

[Repainting process]
The repainting step S3 is a step of repainting the steel member X by applying a new paint on the outside of the rust preventive layer 1 exposed by the peeling of the outer coating layer 2 in the peeling step S2. In this embodiment, the case where the epoxy resin is intermediately coated and then the fluorine resin or the polyurethane resin is overcoated on the outside of the epoxy resin is taken as an example, but the outer coating layer 2 may be composed of other paints. it can. The coating applied to the rust stop layer 1 may be the same as or different from the peeled coating. In applying the paint, undercoating, intermediate coating, and topcoating can be performed as necessary. The coating amount and coating thickness of the paint can be the same as in the existing case. Moreover, you may make it wash | clean the exposed rust prevention layer 1 before apply | coating a new coating material. In addition, a rust preventive material can be applied repeatedly. By repeatedly applying the rust preventive material, rusting from the surface of the steel member X can be prevented even when the rust preventive material is peeled and exposed. In order to enhance the adhesion of new paint, the rust-preventing layer 1 left after peeling off the outer coating layer is reblasted by various blasting methods such as baking soda blasting using vacuum baking soda, vacuum blasting, laser blasting, etc. (S2b process shown by a virtual line in FIG. 1). This reblasting is preferably a blasting that is strong enough to roughen the surface of the rust stop layer 1 in the thickness direction. Excessive blasting that peels (damages) all of the rust stop layer 1 in the thickness direction is desirable. It is desirable to avoid it.

(Embodiment 2)
The second repainting method of the present invention will be described with reference to the drawings. As shown in FIG. 2, the repainting method of this embodiment heats the surface of the steel member X by induction heating of the induction heating device 10 addressed to the outside of the steel member X so that the surface of the steel member X is coated. Among them, the softening step S11 for softening the outer coating layer 2 outside the rust prevention layer 1 and the peeling step S12 for peeling the softened outer coating layer 2 from the rust prevention layer 1 in a sheet state or in a solidified state without scattering by a peeling means. And a cutting step S13 for cutting the rust-preventing layer 1 exposed by the peeling of the outer coating layer 2, and the surface of the steel member X exposed by cutting off the rust-preventing layer 1 left by peeling off the outer coating layer 2 (steel) Rust prevention layer formation process S14 which applies new rust prevention material to member exposed surface) and forms new rust prevention layer, and repainting process S15 which paints new paint on the outside of new rust prevention layer and repaints steel member X It is a thing. For convenience of explanation, an outline of the coating system of this embodiment will be explained prior to explanation of each process.

[Coating system]
The coating system of this embodiment is an A-based coating in which a red lead or lead-based rust-preventing paint is used as a rust preventive material. In this coating system, as shown in FIG. 7B, an etching primer is applied to the surface of the blasted steel member X, and a red lead or lead-based rust-preventing paint is applied to the outside of the etching primer, so that the rust-preventing layer 1 is applied. Is formed. An outer coating layer 2 is formed on the outside of the red lead by applying a resin paint such as a phthalic acid resin paint. The outer coating layer 2 is an example, and the structure of the outer coating layer 2 may be other than this.

[Softening process]
In the softening step S11, the steel member X is heated by induction heating of the induction heating device 10 addressed to the outside of the steel member X, and the outer coating layer 2 outside the rust-preventing layer 1 out of the coating on the surface of the steel member X. Is a step of softening. Through this step, the outer coating layer 2 is separated (raised) from the rust prevention layer 1. The reason why the rust preventive layer 1 is not separated from the steel member X and only the outer coating layer 2 is separated from the rust preventive layer 1 is the same as (1) to (3) in the first embodiment.

[Peeling process]
The peeling step S12 is a step of peeling the outer coating layer 2 softened in the softening step S11 from the rust prevention layer 1 with an existing kawaski or scraper. The outer coating layer 2 is in a state of being softened and separated from the rust preventive layer 1 in the softening step S11, and can be peeled off in a sheet state by Kawaski or the like. Although the peeled outer coating layer 2 may contain PCB, according to the coating film repainting method of the present invention, the outer coating layer 2 can be peeled in a sheet state or in a solid state without scattering. Therefore, it is easy to collect the peeled pieces. However, since some coating remains on the surface of the rust-preventing layer 1 after peeling, it is desirable to scrape the remaining part with kawasuki or the like. The paint of the peeled outer coating layer 2 is collected (outer coating layer collecting step (S12a in FIG. 2)).

[Cutting process]
The cutting step S13 is a step of cutting the rust preventive layer 1 exposed by the peeling of the outer coating layer 2. In this cutting step S13, the thickness direction surface layer side of the rust stop layer 1 is cut and removed (partially cut away) to leave the thickness direction steel member side (deep layer side), or all of the thickness direction is cut and removed ( The steel member X can also be exposed by cutting and removing all of them. For cutting the rust-preventing layer 1, it is desirable to use a cutting machine with a dust collecting function to prevent scattering. For example, existing grinders, sanders, cup brushes, vacuum blasting laser blasting machines and the like can be used. The rust preventive paint of the rust preventive layer 1 that has been cut and removed is recovered in both cases of partial removal and complete removal (S13a in FIG. 2). In the case of partial cutting removal, the remaining deep rust prevention layer (residual rust prevention layer) is roughened by reblasting (S13b in FIG. 2) the exposed steel member exposed surface in the case of complete cutting removal. You can also In this reblasting process, it is desirable that the surface of the residual rust-preventing layer be rough enough to avoid rough blasting that causes the entire surface of the residual rust-preventing layer to peel off (damage). Is desirable. The reblasting of the exposed surface of the steel member is also preferably a blasting with a strength enough to roughen the surface. A vacuum blast, a laser blast, etc. can be used also for this reblast. When vacuum blasting or laser blasting is used for this reblasting, the cutting step (cutting step S13 in FIG. 2) and the reblasting step can be performed simultaneously.

[Rust stop layer forming process]
In the rust-preventing layer forming step S14, the exposed surface of the steel member exposed by cutting and removing all of the original rust-preventing layer 1 or the remaining on the deep layer side left by cutting and removing the surface layer portion of the original rust-preventing layer 1 This is a step of forming a new rust prevention layer by applying a new rust prevention material on the rust prevention layer. The rust preventive layer can be formed by other methods. In this case, a new rust preventive layer having a rust preventive effect is applied to form a new rust preventive layer, and a new paint is applied to the new rust preventive layer to form a new outer coating layer. As the new rust prevention layer, zinc having a higher ionization tendency than steel (Fe), that is, a new rust prevention material mainly composed of Zn is suitable. By applying this new rust preventive material to form a new rust preventive layer, a sacrificial anticorrosive action due to the electrochemical action of the new rust preventive material and the new paint applied thereon can be obtained. As the new rust preventive material, for example, an organic zinc rich paint or an inorganic zinc rich paint can be used. The air hole of the inorganic zinc rich paint is sealed by spraying a mist-like mist coat.

[Repainting process]
The repainting step S15 is a step of forming a new outer coating layer by applying a new paint to the outside of the new rust prevention layer formed in the rust prevention layer forming step S14. In this embodiment, an epoxy resin is intermediately coated on the outer side (upper side) of the new rust preventive layer, and a fluororesin or a polyurethane resin is overcoated on the outer side of the epoxy resin to form an outer coating layer. The new outer coating layer is an example, and the structure of the new outer coating layer may be other than this.

(Induction heating device)
The repainting method of the present invention can be carried out using, for example, the induction heating device 10 shown in FIGS. The induction heating device 10 includes a heating head 11, a current transformer CT, a high-frequency power source 12 (FIGS. 5 and 6), and a circulation device 13 (FIG. 5). When the induction heating device 10 is a low frequency induction heating device, the high frequency power source 12 in FIG. 5 is a low frequency power source. Although the circulation device 13 in FIG. 5 is a water-cooled type, an air-cooled type or other cooling type may be used.

  The heating head 11 includes a base 14, a heating coil 15, coil electrodes 16 a and 16 b provided at both ends of the heating coil 15, and two support members 18 that are erected from the base 14 and arranged to face each other. A device mounting portion 20 disposed and fixed between the support members 18 and a sensor mounting portion 21 mounted on the device mounting portion 20 are provided.

  A metal pipe is used for the heating coil 15, and an internal space of the metal pipe is circulated as a coolant passage by flowing a cooling medium such as cooling water or cooling air (cooling gas). The heating coil 15 shown in FIG. 3 is obtained by bending one metal pipe into an elliptical shape in plan view, and the outer peripheral surface thereof is subjected to insulation treatment. The heating coil 15 has an elliptical portion in plan view arranged in the set space of the base 14, and coil electrodes 16 a and 16 b are provided at both ends thereof. Both ends of the heating coil 15 are connected to through holes 22 provided in the coil electrodes 16 a and 16 b so that a cooling medium can be circulated in the heating coil 15. Stop holes 23 are opened above and below the through hole 22.

  The two support members 18 are L-shaped members, and a device mounting portion 20 is provided between the two support members 18. As an example, the apparatus attachment part 20 shown in FIG. 3 is a metal flat plate, and the recessed part 24 is provided in the rear-end side. A part of a connecting member 25 used for connecting and fixing to the current transformer CT is fitted into the recess 24. A pedestal 26 having a triangular shape in side view is provided on the upper surface of the device mounting portion 20, and a sensor mounting portion 21 is provided on the upper surface of the pedestal 26. An opening is formed in the sensor mounting portion 21, and a non-contact temperature sensor 27 can be inserted into the opening. A general-purpose non-contact temperature sensor 27 can be used as the temperature sensor 27. The temperature sensor 27 is suitable so that the distance to the surface of the steel member X is about 100 mm when the heating coil 15 is directed to the outer periphery of the steel member X. However, this numerical value is an example and may be other than this.

  The current transformer CT is connected to the heating head 11 and the high frequency power source 12 and converts the current from the high frequency power source 12 into a current (large current) suitable for supplying the heating coil 15. For the current transformer CT, a general-purpose current transformer can be used for industrial IH. The portable handheld current transformer CT is preferable from the viewpoint of the convenience of field work.

  The connecting member 25 is connected to the current transformer CT. As an example, the connecting member 25 shown in FIG. 4A is a block made of two metals, and a convex portion 28 is formed on the upper surface of the block. On the side of the connecting member 25, a handle 30 is provided that is held by an operator during work. Semi-disk-shaped power feeding portions (external electrodes) 29 a and 29 b are fixed to the front surface of the connecting member 25. The external electrodes 29a and 29b in FIG. 4 (a) are thick copper plates, and a through hole 31 is penetrated substantially at the center, and a stop hole 32 is opened above and below. A packing 33 for preventing leakage is fitted to the end face of the through hole 31. The packing 33 is molded from an elastic material such as rubber or resin. The external electrodes 29a and 29b may be made of a metal other than copper.

  The current transformer CT is connected to the heating head 11 by fixing the connecting member 25 to the device mounting portion 20 of the heating head 11. Specifically, the external electrodes 29a and 29b of the current transformer CT and the coil electrodes 16a and 16b are brought into contact with each other, the through holes 22 and 31 are communicated with each other, and the convex portion 28 of the connecting member 25 is connected to the concave portion 24 of the device mounting portion 20. The current transformer CT and the heating head 11 are connected to each other by engaging with each other and screwing in place.

  A bellows type protective hose 34 is connected to the current transformer CT. A power cable (not shown) is disposed in the protective hose 34 and a refrigerant hose is piped. The power cable is wired between the external electrodes 29a and 29b and the current transformer CT, supplies an alternating current from the current transformer CT to the external electrodes 29a and 29b, and is connected to the external electrodes 29a and 29b. An alternating current is supplied to the heating coil 15 from 16b. The refrigerant hose includes a supply hose 35 for supplying a cooling medium into the heating coil 15 and a return hose 36 for returning the cooling medium that has passed through the heating coil 15. Both hoses 35 and 36 are connected to the circulation device 13 and the through holes 31 of the external electrodes 29a and 29b, and the circulation device 13—the water absorption hose 35—the cooling plate 38 of the high frequency power supply 12—the through holes 31 of the external power supplies 29a and 29b—the coil. The cooling plate 38 and the heating coil 15 are cooled by circulating through the through holes 22 of the electrodes 16a and 16b, the refrigerant passage in the heating coil 15, the return hose 36, and the cooling path of the circulation device 13. The cooling path is provided with an electromagnetic valve 40 for adjusting the flow rate and a backflow prevention valve 41 together with a platinum-side warm body 39 for measuring the temperature of the cooling medium.

  A cable 42 is disposed outside the protective hose 34, a temperature sensor 27 is connected to one end thereof, and an amplifier 43 that amplifies a detection signal from the temperature sensor 27 is connected to the other end thereof.

  Although not shown, the induction heating device 10 includes, for example, a power switch, an output controller, a timer, a power meter, a work temperature indicator, a refrigerant temperature indicator, a heating on indicator lamp, an alarm reset switch, an emergency stop switch, It can be operated with a control panel equipped with a non-contact sensor amplifier, a push button switch of the current transformer CT, and the like. The control panel can also be operated remotely.

  The power switch is for turning on the power, the output controller is for setting the output with the output adjustment volume, the timer is for setting the heating off time, the power meter is for displaying the power when the heating is on, the work temperature indicator Is for setting the upper limit temperature of the non-contact temperature sensor 27 (FIG. 6), the refrigerant temperature indicator is for setting the upper limit temperature of the platinum temperature measuring element 39 (FIG. 5) on the cooling medium inlet side, and the heating on display The lamp indicates that the heating switch on the current transformer CT side is on, the alarm reset switch resets the alarm, the emergency stop switch stops heating on in an emergency, non-contact sensor amplifier (temperature sensor amplifier) ) Captures and amplifies the detection signal of the non-contact temperature sensor 27 (FIG. 6), and the push button switch of the current transformer CT switches between heating on and heating off. It is intended.

  The apparatus used is an example, and the repainting method of the present invention can be carried out using another induction heating apparatus.

Example 1
A first embodiment of the repainting method of the present invention will be described with reference to FIG. This example is an example in the case where the repainting method described in the first embodiment is performed using the use device.
(1) Prior to repainting, prepare scaffolding, anti-scattering equipment, etc. (preparation).
(2) Place the induction heating device 10 on the surface of the steel member X to be repainted.
(3) In a state where the surface of the steel member X is addressed, the switch of the current transformer CT is turned on to supply AC power to the induction heating device 10, and the steel member X is heated by induction heating.
(4) The induction heating device 10 is moved along the steel member X while maintaining the state of (3). At this time, it is preferable that the moving speed of the induction heating apparatus 10 is set to a speed at which the heating target portion is about 150 ° C. to 200 ° C.
(5) When the steel member X is heated by induction heating by the induction heating device 10, the outer coating layer 2 is softened by the heat and separated from the rust prevention layer 1 ((2) to (5) are softening step S1).
(6) The outer coating layer 2 separated from the rust preventive layer 1 is peeled off in a sheet state or in a state where it does not scatter with a kawaski or scraper. When the coating remains on the surface of the rust preventive layer 1 after peeling, the remaining coating is also scraped off with a Kawasuki, a scraper or the like (peeling step S2).
(7) The peeled piece peeled off in a sheet state or in a state where it does not scatter, and the remaining paint piece scraped with kawasuki or the like are collected (outer coating layer collecting step S2a). In some cases, the surface of the rust-preventing layer 1 is blasted with baking soda blasting using baking soda as a grinding material, vacuum blasting or laser blasting capable of adjusting the substrate (reblasting process: S2b in FIG. 1 can also be performed. The blasting in this case is performed to such an extent that the rust prevention layer 1 is not damaged excessively.
(8) A new paint is applied to the outside of the rust preventive layer 1 exposed by the peeling of the outer coat layer 2 or the rust preventive layer 1 reblasted as described above to form a new outer coat layer (repainting step S3).

(Example 2)
A second embodiment of the repainting method of the present invention will be described with reference to FIG. This example is an example in the case where the repainting method described in the second embodiment is carried out using the use device.
(1) Prior to repainting, prepare scaffolding, anti-scattering equipment, etc. (preparation).
(2) Place the induction heating device 10 on the surface of the steel member X to be repainted.
(3) In a state where the surface of the steel member X is addressed, the switch of the current transformer CT is turned on to supply AC power to the induction heating device 10, and the steel member X is heated by induction heating.
(4) The induction heating device 10 is moved along the steel member X while maintaining the state of (3). At this time, it is preferable that the moving speed of the induction heating apparatus 10 is set to a speed at which the heating target portion is about 150 ° C. to 200 ° C.
(5) When the steel member X is heated by induction heating by the induction heating device 10, the outer coating layer 2 is softened by the heat and separated from the rust preventive layer 1 ((2) to (5) are softening step S11).
(6) The outer coating layer 2 separated from the rust preventive layer 1 is peeled off in a sheet state or in a state where it does not scatter with a kawaski or scraper. When the coating remains on the surface of the rust preventive layer 1 after peeling, the remaining coating is also scraped off with a Kawasuki, a scraper, or the like (peeling step S12).
(7) Collect the peeled piece peeled off in a sheet state or in a state where it does not scatter and the remaining paint piece scraped with Kawasuki (outer coating layer collecting step S12a).
(8) The rust-preventing layer 1 exposed by peeling off the outer coating layer 2 is removed by cutting with a mechanical device such as a grinder, a sander, a cup brush, a vacuum blast, a laser blast, or the like, and a part or all of the surface of the steel member X is exposed. Let
(9) The cutting powder of the cut rust prevention layer 1 is collected (rust prevention layer collection process S13a). However, in the case of vacuum blasting, there is a collection function, so there is no need to collect separately from blasting. In the case of laser blasting, the coating vaporizes.
(10) Applying inorganic zinc as a new rust inhibitor to the exposed surface of the steel member exposed by cutting the rust preventive layer 1 and spraying a mist-like mist coat from the outside of the inorganic zinc to fill the air holes in the inorganic zinc. Then, a new rust preventive layer 1 is formed (rust preventive layer forming step S14). The steel member X may be blasted again by vacuum blasting or the like before applying the new rust preventive material (reblasting step S13b). In the case of vacuum blasting or laser blasting, the antirust layer recovery step S13a and the reblasting step S13b can be performed simultaneously.
(11) A new paint is applied to the outside of the new rust prevention layer 1 to form a new outer coating layer 2 (repainting step S15).

(Other examples)
Both of the above-mentioned embodiments are examples, and the paint repainting method of the present invention can be carried out by other procedures.

  The repainting method of the present invention can be applied to the repainting of various steel structures, but various anticorrosion coatings such as steel girders of steel bridges, marine structures, tanks, sluices, plants, various steel towers are adopted. This method is particularly suitable for repainting steel members.

1 Rust prevention layer 2 Outer coating layer 10 High frequency induction heating device (induction heating device)
DESCRIPTION OF SYMBOLS 11 Heating head 12 High frequency power supply 13 Circulation apparatus 14 Base 15 Heating coil 16a, 16b Coil electrode 18 Support material 20 Equipment attachment part 21 Sensor attachment part 22 Through-hole 23 Stopping hole 24 Concave part 25 Connection material 26 Base 27 Temperature sensor 28 Convex part 29a , 29b Power feeding part (external electrode)
30 Handle 31 Through-hole 32 Stopping hole 33 Packing 34 Protection hose 35 Supply hose 36 Return hose 38 Cooling plate 39 Platinum side warming body 40 Flow rate adjustment valve 41 Backflow prevention valve 42 Cable 43 Amplifier CT Current transformer X Steel member

Claims (7)

It is a method of peeling the paint on the steel member surface and repainting the paint,
A softening step of heating the steel member surface by induction heating of the induction heating device addressed to the outside of the steel member to soften the outer coating layer outside the rust-preventing layer among the coating of the steel member surface;
A peeling step of peeling the softened outer coating layer in a sheet state or a solidified state without scattering from the rust-preventing layer by a peeling means;
It was equipped with a repainting process that repaints steel members by applying a new paint to the existing rust prevention layer exposed by peeling off the outer coating layer.
A paint repainting method characterized by that. In the paint repainting method according to claim 1,
It has a reblasting process that blasts the existing rust prevention layer exposed by peeling off the outer coating layer,
A repainting step of repainting the steel member by applying a new paint to the blasted existing rust-preventing layer,
A paint repainting method characterized by that. It is a method of peeling the paint on the steel member surface and repainting the paint,
A softening step of heating the steel member surface by induction heating of the induction heating device addressed to the outside of the steel member to soften the outer coating layer outside the rust-preventing layer among the coating of the steel member surface;
A peeling step of peeling the softened outer coating layer in a sheet state or a solidified state without scattering from the rust-preventing layer by a peeling means;
A cutting step of cutting a part or all of the rust-preventing layer exposed by peeling of the outer coating layer;
A rust-preventing layer forming step of applying a new rust-preventing material by applying a new rust-preventing material to the remaining rust-preventing layer left partially cut in the cutting step, or a steel member exposed surface that is completely cut and exposed, and
A repainting step of repainting the steel member by applying a new paint on the outside of the new rust prevention layer,
A paint repainting method characterized by that. In the paint repainting method according to claim 3,
A re-blasting process for blasting a residual rust-preventing layer left by partial cutting or a steel member exposed surface exposed by full cutting,
A rust-preventing layer forming step of forming a new rust-preventing layer by applying a new rust-preventing material to the blasted residual rust-preventing layer or the exposed surface of the steel member,
A repainting step of repainting the steel member by applying a new paint on the outside of the new rust prevention layer,
A paint repainting method characterized by that. In the paint repainting method according to claim 3 or claim 4,
Applying a rust-preventing material mainly composed of zinc, which has a higher ionization tendency than steel, to form a new rust-preventing layer, and sacrificial anticorrosion due to the electrochemical action of the new rust-preventing layer and the new paint applied on it. So that the action can be obtained,
A paint repainting method characterized by that. In the paint repainting method according to any one of claims 1 to 5,
Induction of the coating film can be separated while leaving the rust-preventing layer by mechanical bonding between the rust-preventing layer and the steel member using the difference in expansion coefficient between the rust-preventing layer and the outer coating layer and the unevenness caused by blasting to the steel member surface The heating temperature by the heating device was set to a temperature at which the surface temperature of the steel member to be peeled was 150 ° C. to 200 ° C.,
A paint repainting method characterized by that. In the paint repainting method according to any one of claims 1 to 6,
The coating system of the steel member before repainting is a coating system in which inorganic zinc rich paint is used as a rust preventive material, or a coating system in which red lead or lead-based antirust paint is used.
A paint repainting method characterized by that.