JP2016065443A - Maintenance coating method of steel structure and circulation type blast device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a maintenance coating method of a steel structure and a circulation type blast device used therefor, capable of largely shortening a construction period, and capable of also largely reducing cost.SOLUTION: A maintenance coating method uses a circulation type blast device 1 capable of injecting grit and a shot, and executes shot-peening processing by using the shot for improving fatigue strength to a blast-processed part of expressing a basis material surface, by executing blast processing by using the grit to a steel bridge K, and applies the final finish coating to a shot-peening-processed part thereafter.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a maintenance painting method for painting a surface of a steel structure such as a steel bridge, a tunnel, and a factory plant, and a circulating blasting device used therefor.

  Conventionally, steel structures such as steel bridges are regularly repainted (maintenance coating) for the purpose of preventing the occurrence of rust and the like, and for repainting the coating that has been discolored due to aging. In order to perform repainting, it is necessary to remove old paint, rust, and the like. In recent years, it has been removed by blasting (one kind of keren) and then a new paint is applied.

  However, normally, the abradant used for such blasting treatment uses an almandite garnet made of natural minerals or iron-making slag which is made of minerals. If such an armandite garnet or steel slag is used for the abrasive, the abrasive will be crushed during the blasting process, generating much more waste than the exfoliation such as the old paint film that is originally desired to be removed. End up. In particular, when PCB (polychlorinated biphenyl) or lead is used for the old coating film, it becomes specially controlled industrial waste including not only the old coating film removed but also the abrasive used for blasting, This process is very expensive.

  For example, Japanese Patent Application Laid-Open No. H10-228561 discloses that after the scouring material and dust are collected in a collection tank, the scouring material and dust are separated and classified in the collection tank. A structure surface polishing system that collects dust and the like while reusing the separated abrasive is disclosed.

  Further, apart from the above problem, the steel structure may be uneven in strength at the welding location. Here, for example, in the case of steel road bridges, fatigue cracks may occur from welds where the strength is biased by the entire bridge being shaken or vibrated when a vehicle passes or strong winds blow. The problem that occurs occurs. For this reason, the actual situation is that a huge expense is required for the repair.

  For example, Patent Document 2 discloses a preventive maintenance method for a steel structure in which the occurrence of cracks is prevented and maintained by applying a primer to a structural discontinuity caused by a welded joint of the steel structure.

  Patent Document 3 discloses a method for improving the fatigue performance of a welded joint in which ultrasonic peening is performed on the end face of the welded joint and the weld toe at the end of the welded joint.

JP-A-11-207624 JP 2006-102738 A JP 2006-142367 A

  However, the conventional configuration as described above still has a long construction period and of course the cost is enormous.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a steel structure maintenance coating method capable of greatly shortening the construction period and thereby greatly reducing the cost, and a circulating blasting apparatus used therefor.

  The present invention is a maintenance painting method for a steel structure, in which a blasting process is performed using a grit as an abrasive to adjust the substrate to the steel structure, and the portion for adjusting the substrate Step B for performing shot peening treatment using shots for improving fatigue strength, and step for applying final finish coating to the portion for adjusting the substrate after performing Step A and Step B C is a maintenance coating method for steel structures characterized by comprising C. Either of the order of the process A and the process B may be first, and in particular, the process B is shot peening using a shot on the blasted portion where the bare surface is exposed by performing the process A. It is a process to perform the process, and it is desirable to execute the process C for applying the final finish coating to the shot peened processed part formed by performing the process B.

  In such a configuration, when shifting from the blasting process to the shot peening process, it is possible to perform the shot peening process as it is on the ground surface exposed by the blasting process, so it is not necessary to perform each work separately. The construction period can be shortened effectively and the cost can be reduced. In general, in the blasting process, a scaffold is assembled or a dustproof sheet is stretched to prevent dust from leaking to the outside. In the present invention, such peripheral equipment is removed. Since the shot peening process can be performed continuously without any work, there is no waste in the work process.

  Further, the grit and the shot are injected by using the same injection device in the step A and the step B, and the grit and the shot are switched between the step A and the step B, and the grit or the shot is changed. A configuration is proposed that includes a shot changing step of loading the gas in a jettable manner.

  By adopting such a configuration, each process can be executed by using a common injection device in the process A and the process B, so that the work efficiency is dramatically improved.

  The blasting, grit, and shot in the present invention are respectively defined in JIS Z 03120: 2004 “General Rules for Blasting Method for Substrate Adjustment”. Specifically, the blasting process is “to remove the oxides or deposits on the steel surface by causing a grinding material having a large kinetic energy to collide with the surface of the steel material to be treated, and finely cutting and striking the steel surface. To clean and roughen the surface. " The grit is “an angular shape having a ridge angle (ridge angle) in a state before use, and a round portion having less than half of the particle”. A shot is “a spherical particle having a major axis (ridge angle), a crushing surface, or other sharp surface defects and having a major axis within twice the minor axis before use”. In the blasting process, “abrasive” is synonymous with the above-mentioned “abrasive”. Moreover, in JIS B 2711: 2013 “Spring shot peening”, shot peening is “improvement of fatigue strength and stress corrosion cracking resistance by hitting the surface layer of the spring with spherical hard particles at high speed. “A cold working method that gives compressive residual stress to the surface and hardens the surface.” However, a surface treatment method called shot peening performed on a metal material other than a spring is common, and the same applies to shot peening for a steel structure in the present invention. That is, in the present invention, the abrasive used for performing the blasting treatment corresponds to the grit, and the hard particle used to perform the shot peening treatment corresponds to the shot. In addition, what is called a steel cut wire may be employ | adopted as a grit. Moreover, what is called a round cut wire may be employ | adopted as a shot.

  Further, the used grit and the used shot that are mixed with each other and sprayed on the steel structure are collided at a constant speed toward the reflector provided at a predetermined position, and the reflected grit and the reflected A configuration is proposed that includes a step of separating the used grit and the used shot based on the difference in the distance at which the shot rebounds.

  In such a configuration, for example, when the grit and the shot are made of a metal-based abrasive, the abrasive is not crushed during use, so that the abrasive can be used repeatedly. By the way, even if used grit and used shot are mixed, they can be easily separated by the above processing. In other words, the angular grit and the spherical shot have different rebound distances due to the difference in shape when colliding with the reflector at the same speed. Specifically, when the grit having an angular shape collides with the reflector at the corner or surface, a constant repulsive force cannot be obtained and the grit is reflected irregularly. On the other hand, a spherical shot always receives a constant repulsive force in the reverse direction passing through the center of gravity (the center of the sphere) and regularly reflects, so that the rebound distance is stabilized and longer than the grit. By paying attention to the rebound distance between the grit and the shot based on this principle, it becomes possible to easily separate the used grit and the used shot without using a large-scale device. The sorted used grit and used shot can be used again for the blasting process and the shot peening process.

  Further, the grit and / or the shot is made of stainless steel, and a used grit and / or a used shot made of stainless steel that is used by being sprayed onto the steel structure is collected. And a salt washing step for washing the collected used grit and / or the collected used shot to remove salt adhering to the surface of the used grit and / or the used shot, and the salt washing After the process, a configuration is proposed that includes the washed grit washed and / or a drying process for drying the washed used shot.

  Here, in the case of a stainless steel grit, the form other than the material conforms to the provisions of JIS Z 0310: 2004 as described above. As the stainless steel, martensitic stainless steel, ferritic stainless steel, austenitic stainless steel, austenitic / ferritic duplex stainless steel, and precipitation hardening stainless steel can be applied. Further, when the shot is made of stainless steel, it shall conform to the provisions of JIS Z 0310: 2004 as with the grit.

  In such a configuration, it is possible to repeatedly use a stainless steel grit and / or shot. Then, after the used grit and / or the used shot are washed and dried, they can be used again for the blasting or the like.

  Here, a problem that occurs when the maintenance painting method for steel structure of the present invention is applied in a cold region will be described. In addition, although the case where a grid is used is illustrated and demonstrated, it is applicable similarly about a shot. That is, treatment agents such as antifreezing agents used for antifreezing and rust prevention are generally attached to the paint on the surface of steel structures in cold regions. Since such a treatment agent contains salt, the salt adheres to the surface of the grit used in the blast treatment. Therefore, in order to reuse the used grit for blasting again, it is necessary to use it after removing attached salt to prevent salt damage. In this configuration, the used grit can be washed and dried to remove salt attached by blasting. Therefore, according to this structure, even when using in a cold region, salt content can be removed from the used grit and it can be used again for blasting.

  Further, the present invention is a circulation type blasting device used in the maintenance painting method for the steel structure, wherein the used grit and the used shot which are mixed and used for the steel structure are mixed. And a dust suction means for sucking dust including at least the release coating film generated in step A, and a separation chamber into which the dust sucked by the dust suction means is introduced. A flow path in which the dust sucked by the dust suction means moves along the air flow is formed, the reflection plate is disposed on the downstream side of the flow path, and the separation chamber further includes A used grit collecting unit for collecting used grit reflected by the reflecting plate by moving the used grit, and a used shot collecting unit for collecting used shots reflected by the reflecting plate by moving through the flow path, Dust suction hand A release coating recovery unit for recovering the release coating floating in the flow path by the air flow by a circulating blasting apparatus characterized by is provided.

  By adopting such a configuration, it is possible to efficiently separate grit and shot. Moreover, a peeling coating film can be efficiently collect | recovered by using the air flow produced | generated by the said dust suction means for collection | recovery of the said peeling coating film. In addition to the release coating film, the dust may contain rust and the like.

  Further, the present invention is a circulation type blasting apparatus used in a maintenance coating method for a steel structure in which the grit and / or shot is made of stainless steel, and is used by spraying the steel structure. A dust suction means for sucking dust including at least the used grit and the used shot mixed, and a separation chamber into which dust sucked by the dust suction means is introduced; A flow path in which the dust sucked by the dust suction means moves along the air flow is formed, and the separation chamber further includes a used grit collection unit that collects the used grit that moves in the flow path, A used shot collection unit that collects used shots that move in the flow path, and is provided to the used grit collection unit and the used shot collection unit. Of the used grit and used shot, the used grit made of stainless steel and / or the used shot made of stainless steel that has been sprayed on the steel structure is washed to use the used grit And / or a salt cleaning means for removing salt adhering to the surface of the used shot, and a drying means for drying the used grit washed by the salt washing means and / or the washed used shot. This is a circulation type blasting device.

  In such a configuration, when used in a cold district as described above, the used grit and the used shot can be reused because the used grit and salt attached to the shot can be removed.

  The steel structure maintenance coating method of the present invention aims to improve the fatigue strength and stress corrosion cracking resistance of the steel structure by not only peeling the coating film to be peeled off by blasting but also performing shot peening treatment. be able to. Moreover, the circulating blasting apparatus of the present invention can efficiently separate dust including used grit, used shots, and a release coating.

It is a flowchart which shows the procedure of the maintenance coating of the steel bridge concerning an Example. It is a schematic explanatory drawing explaining the circulation type blasting apparatus concerning an Example. It is explanatory drawing which cut | disconnects and shows the separation chamber concerning an Example. It is a schematic explanatory drawing explaining the circulation type blasting apparatus concerning another Example.

  Embodiments of the steel structure maintenance coating method according to the present invention and the circulating blasting apparatus used therefor will be described in detail below. In addition, this invention is not limited to the Example shown below, A design change is possible suitably.

  As shown in FIG. 1, as a maintenance painting procedure for a steel bridge (steel structure), a scaffold is temporarily set on a steel bridge to be subjected to maintenance painting. At the same time, a dustproof sheet is stretched so as to prevent dust from leaking to the outside, the non-painted portion is cured, and a preliminary preparation for installing a device for performing blasting and shot peening is performed (S101).

  Thereafter, the type and thickness of the old paint film applied to the steel bridge, the situation of the steel bridge, etc. are investigated (S102). Then, based on the investigation result, the type of grit and shot to be used, the injection speed, and the like are determined. Here, both the grit (non-spherical) and the shot (spherical) to be selected are defined in JIS Z 0310: 2004.

  A blast process is first performed using the grit determined in S102 (S103). Specifically, peeling of the coating film to be peeled from the steel bridge and substrate preparation are performed. By such blasting, step A in the present invention is configured. In addition, although the coating film, rust, etc. peeled off by the blast treatment and used grit are generated as dust, since the dustproof sheet is stretched in S101, the dust does not leak to the outside, and the dust Will accumulate at the work site.

  Subsequently, the shot determined in S102 is loaded in place of the grit to the blasting apparatus that has injected the grit so that the shot can be injected. This process constitutes the shot changing process according to the present invention.

  Then, the shot peening process is performed on the blasted part where the ground surface is exposed by the blasting process using the blasting apparatus replaced with the shot (S104). By such treatment, a process B is formed in which the fatigue strength and stress corrosion cracking resistance of the base material are improved. The used shot generated by the shot peening process is accumulated as dust on the work site as it is mixed with the used grit in S103. By the way, the shot peening process may be performed on all the ground surfaces on which the blasting process has been performed, or may be performed appropriately on the periphery of the welded part, a part where the strength is uneasy, or the like.

  Thereafter, the ground surface on which the blasting process and the shot peening process have been performed is confirmed (S105). Such confirmation includes not only visual confirmation but also comparison using, for example, an ISO8501 blast photo book, or roughness confirmation using a surface roughness measuring instrument. As a result, it is confirmed whether an unexfoliated coating film remains, or whether the roughness of the ground surface is within the specification, and an appropriate process is performed on an insufficient portion. For example, the base adjustment is performed using a hand tool or the like in a portion where the blasting process cannot be performed.

  In this way, the final finish coating for forming the final coating film is performed on the portion where the ground surface has been confirmed (S106). By such a coating process, the process C according to the present invention is configured. Such coating is generally applied in layers such as undercoating as an anticorrosion coating, intermediate coating for protecting the anticorrosion coating, and topcoating as the final finish coating. .

  When the painting is completed, the confirmation (S107) is performed. Such confirmation includes not only confirmation of the film thickness after the coating has dried, but also confirmation of the wet film thickness using a wetness gauge during the painting operation, for example. Further, such confirmation is performed not only after the top coat which is the final finish paint, but also during the undercoat and intermediate coats.

  When the painting operation is completed by the confirmation, the site is cleaned up (S108). Specifically, the maintenance coating is completed by collecting the scaffold, dustproof sheet, and the like, and withdrawing the blast-shot peening injection device.

  In addition to the above procedure, a dust collecting step is executed (S110). Specifically, the used grit generated in the blasting process (S103), the used shot generated in the shot peening process (S104), and dust containing exfoliation and rust generated in each process are separated. While collecting.

  Since the collected used grit and used shot are both iron (metal) abrasives specified in JIS Z 0310: 2004, even if they collide with a steel bridge at the time of use, they are like Almandite garnet or iron slag. And can be reused. Among them, high carbon cast steel can be reused about 600 times, and it is very economical, and the amount of waste can be greatly reduced by separating it from the peeled coating film and other foreign matters. .

  Hereinafter, it is possible to inject the grit and the shot with a common device, and also to collect the used grit, the used shot, the peeled coating film, and the like, and to circulate the blasting device 1 This will be described as an example.

  As shown in FIG. 2, the circulating blast apparatus 1 includes an apparatus main body 2 that is installed adjacent to a work site α of a steel bridge K that is a work target. Furthermore, the apparatus main body 2 includes a pressure feeding hose 4, and an injector 3 is connected to the tip of the pressure feeding hose 4. Grit g and shot s are ejected from the injector 3. Moreover, the said apparatus main-body part 2 comprises the suction hose 5, and the front-end | tip of this suction hose 5 is arrange | positioned at the work site (alpha). As a result, the used grit g ′ generated at the work site α, the used shot s ′, and the dust X composed of the foreign matter D including the peeled coating film, rust, and the like can be sucked through the suction hose 5. it can. In order to prevent dust from leaking outside, a dustproof sheet (not shown) is stretched on the work site α, and a blower, a dust collector, and the like are also installed as appropriate.

  As shown in FIG. 2, a grit hopper tank 10 and a shot hopper tank 20 are disposed adjacent to each other in the apparatus main body 2 of the circulating blast apparatus 1. More specifically, the grit hopper tank 10 has a function of storing grit g and used grit g ′ (hereinafter, a mixture thereof is referred to as grit G). The shot hopper tank 20 has a function of storing shots s and used shots s' (hereinafter, a mixture thereof is referred to as shot S). The grit hopper tank 10 is connected to a grit pressure tank 11 for pressure-feeding the grit G stored in the grit hopper tank 10 to the work site α. Similarly, the shot hopper tank 20 is connected to a shot pressurizing tank 21 for pressure-feeding the shot S stored in the shot hopper tank 20 to the work site α.

  Further, a dry compressed air supply means 30 is connected to the grit pressure tank 11 and the shot pressure tank 21 via a dry compressed air pipe 31. The dry compressed air supply means 30 includes an air compressor and an air dryer for supplying dry compressed air. Further, the dry compressed air pipe 31 is provided with a switching valve 32 so that the dry compressed air can be selectively supplied to the grit pressurizing tank 11 or the shot pressurizing tank 21, and shot instead of the grit. Can be loaded in such a way that it can be jetted.

  The pressure feeding hose 4 is connected to the grit pressure tank 11 and the shot pressure tank 21. And by this structure, the grit G or the shot S is injected from the injector 3 through the pumping hose 4 by the air pressure by the dry compressed air supplied from the dry compressed air supply means 30, and the steel bridge K to be operated In addition, blast processing or shot peening processing can be executed. In addition, the injection device (blast-shot peening injection device) according to the present invention is configured by the circulating blast device 1 having the functions so far.

  Dust X including foreign matter D such as used grit g ', used shot s', and peeled coating film deposited at the work site α is sucked together from one end of the suction hose 5. The dust X sucked by the suction hose 5 reaches the separation chamber 40.

  In addition, a dust hose 51 is attached to the separation chamber 40, and a dust recovery unit 50 as a release coating film recovery unit is connected to the dust hose 51. Further, an air suction device 60 as a dust suction means is connected to the dust collection unit 50. Therefore, the dust X can be sucked by the air suction force of the air suction device 60.

  Here, as shown in FIG. 3, the separation chamber 40 has a channel 41 that is horizontally long and airtight, and an inlet 42 on the upstream side (left side in FIG. 3) of the channel 41. Is provided. In addition, a reflection plate 43 that is inclined with respect to the flow path direction of the flow path 41 is attached to the downstream side. Further, a discharge portion 44 is provided below the reflecting plate 43. In addition, a used grit collection unit 45 is disposed on the upstream side with respect to the discharge unit 44, and a used shot collection unit 46 is disposed on the upstream side of the used grit collection unit 45. The discharge part 44 is connected to the dust hose 51 and is connected to the air suction device 60 via the dust recovery part 50, and the air flow in the separation chamber 40 takes the suction port 42 upstream. The discharge part 44 is located downstream.

  Here, the dust X introduced into the flow path 41 from the suction hose 5 via the suction port 42 is maintained in the flow path 41 while maintaining a predetermined speed by the air suction force of the air suction device 60. move on. Then, the foreign matter D such as a peeled coating film or rust having a low specific gravity is directly discharged to the discharge portion 44 along the air flow in the flow path 41. The discharged foreign matter D is introduced into the dust collecting unit 50 through the dust hose 51 and accumulated in the dust collecting unit 50, and is discharged into the waste bag 52 at a desired timing and processed as industrial waste. .

  In addition, the used grit g ′ and the used shot s ′ are iron (metal-based) abrasives, and therefore have a high specific gravity. It goes straight according to inertia and collides with the reflector 43. At this time, the used shot s' rebounds most efficiently because it has a spherical shape as described above. On the other hand, since the used grit g 'has an angular shape, the rebound is smaller than that of the used shot s'. Based on the difference in the rebounding distance, the used grit collection part 45 is provided near the reflector 43 near the lower part of the flow path 41 and closer to the suction port 42 than the discharge part 44. The used shot collection unit 46 is provided farther from the reflector 43 (closer to the suction port 42) than the used grit collection unit 45. With this configuration, the foreign matter including the used grit g ′, the used shot s ′, and the peeled coating film by using only the air suction force of the air suction device 60 without using a mechanical operation such as a vibration sieve. It becomes possible to sort each D. The used grit g 'thus separated is returned to the grit hopper tank 10 below the sorting chamber 40 and reused. Similarly, the used shot s ′ is also returned to the shot hopper tank 20 below the sorting chamber 40 and reused. In this way, the grid G and the shot S can be circulated and used continuously.

  Other than the above-described embodiments, the design can be changed as appropriate. For example, the switching valve 32 may be provided in the work site α so that the operator H at the work site α can perform switching operation, or may be remotely operable. Further, the injector 3 and the suction hose 5 may be separate or may be integrated (vacuum blast type). Further, the dry compressed air supply means 30 may be provided separately for the grit pressurization tank 11 and the shot pressurization tank 21, respectively. Further, the pressure feeding hose 4 may be provided separately for grit and shot. Similarly, the injector 3 may be divided into a grit and a shot. Moreover, the separation chamber 40 does not need to be disposed immediately above the grit hopper tank 10 and the shot hopper tank 20, and the position is not particularly limited. In addition, the method for realizing the airtight space in the flow path 41 is not particularly limited. For example, the hopper tanks 10 and 20 may be in an airtight state while communicating with the grit hopper tank 10 and the shot hopper tank 20, or a dedicated tank for temporarily storing the grit G or the shot S may be disposed at a desired timing. Thus, the grid G and the shot S may be supplied to the hopper tanks 10 and 20. In addition, it is desirable to be able to supply a new product when the grit amount or shot amount in the circulating blast device 1 is less than a specified value. Further, the apparatus main body 2 may be placed on a vehicle and movable, for example. Moreover, you may apply the maintenance coating method of this invention not only at the time of repainting of a steel structure but to the steel structure newly constructed.

  On the other hand, a circulating blast device 81 according to another embodiment will be described below. The circulating blast device 81 uses a stainless steel grit and a stainless steel shot, and is used in an environment in which salt is sprayed onto a bridge or the like. The example of this another example is the same as the above example except that stainless steel grit g and shot s are used and cleaning devices 85 and 86 and drying devices 87 and 88 are provided. Therefore, the same components are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 4, the apparatus main body portion 82 of the circulating blast apparatus 81 is provided with salt cleaning devices 85 and 86 and drying devices 87 and 88, which are arranged vertically. Specifically, a grit salt cleaning device 85 and a drying device 87 are disposed directly under the grit hopper tank 10, and a shot salt cleaning device 86 and a drying device 88 are disposed directly under the shot hopper tank 20. ing. The salt cleaning devices 85 and 86 constitute the salt cleaning means according to the present invention. The drying devices 87 and 88 constitute the drying means according to the present invention.

  The salt cleaning devices 85 and 86 perform washing with fresh water, respectively, store a predetermined amount of used grit g ′ and used shot s ′ in a predetermined tank, and eject fresh water to wash in the tank. To remove salt adhering to the surface. Thereafter, the stored used grit g 'and the used shot s' are transferred down to the drying devices 87 and 88, respectively. The drying devices 87 and 88 are for drying with hot air. The used grit g ′ and the used shot s ′ flowing down from the salt content cleaning devices 85 and 86 are stored and dried by exposing them to hot air for a predetermined time. Thereby, the water | moisture content adhering with the said salt content washing | cleaning apparatuses 55 and 56 is skipped. Thereafter, the stored used grit g ′ and the used shot s ′ are transferred to the grit pressurizing tank 11 and the shot pressurizing tank 21, respectively, and transferred.

  In the case of using such a circulation type blasting device 81 of another example, since the water is washed by the salt content washing devices 85 and 86, stainless steel having excellent corrosion resistance is used for the grit g and the shot s. Even in the grit g and the shot s of these stainless steels, the shape thereof is the same as that of the metal grinding material of the above-described embodiment, and those according to JIS Z 0310: 2004 are preferable except for the material.

  Another example of the circulating blasting device 81 described above is suitable for use in cold regions where a paint containing salt is used to prevent freezing or rust. That is, when the circulation type blasting device 81 is used for a steel bridge in a cold region, the used grit g ′ generated by the blasting process adheres to the salt contained in the paint, and further the shot peening process. There is also a concern that the used salt s ′ generated in step 1 may adhere to the salt. The used grit g ′ and the used shot s ′ are sucked together with the foreign matter D and separated in the separation chamber 40. The used grit g ′ is freed of salt attached to the surface by the cleaning device 85, and then the moisture attached by the cleaning device 85 is blown off by the drying device 87. After that, it can be used again. Similarly, the used shot s ′ is salt-removed by the cleaning device 85 and then dried by the drying device 87. After that, it can be used again. As described above, according to the circulation type blasting device 81 of another example, salt attached to the used grit g ′ and the used shot s ′ can be removed and used again, so that it can be suitably used in a cold district. .

  In addition, in this Example of another example, a salt cleaning apparatus and a drying apparatus are not limited to the structure mentioned above, It can change suitably. For example, it is also possible to apply an apparatus that can execute a salt cleaning process and a drying process in a single unit. In this apparatus, a configuration in which a belt conveyor for transfer is provided between a site where the salt content cleaning process is performed and a site where the drying process is performed is preferable. In this configuration, the salt washing process and the drying process can be sequentially performed in the process of being transferred by the belt conveyor. Further, even in the above-described another example, it is possible to adopt a configuration in which a belt conveyor is used as a transfer unit from the salt content cleaning device to the drying device. Furthermore, in the above-described another example, the salt content cleaning device and the drying device can be disposed only in the path for the used grit collection unit of the separation chamber. In this case, only the used grit with much salt content can be washed and dried to remove the salt content.

1,81 Circulating blast device 40 Separation chamber 41 Flow path 43 Reflector plate 45 Used grit collection unit 46 Used shot collection unit 50 Dust collection unit (peeling coating film collection unit)
60 Air suction device (dust suction means)
85 Salt cleaning equipment (salt cleaning means)
86 Drying equipment (drying means)
G Grit S Shot K Steel bridge (steel structure)

Claims (7)

Conservation painting method for steel structures,
A process A for performing a blasting process using a grit as an abrasive material in order to adjust the substrate for the steel structure;
Step B for performing shot peening treatment using a shot to improve fatigue strength with respect to the portion for adjusting the substrate;
After performing the step A and the step B, a step C for applying a final finish coating to the portion for adjusting the substrate;
Conservation painting method for steel structures characterized by containing Step B is
It is a step of performing shot peening processing using a shot for the blasted portion where the bare ground surface has been exposed by performing the step A,
The maintenance coating method of the steel structure of Claim 1 which performs the process C which performs the final finish coating with respect to the shot-peened process completed part formed by performing the said process B. In the step A and the step B, the same injection device is used to inject the grit and the shot. The grit and the shot are switched between the step A and the step B, and the grit or the shot is injected. The maintenance painting method of the steel structure of Claim 1 or Claim 2 including the shot replacement | exchange process loaded with possible. The used grit and the used shot, which are mixed with each other and sprayed onto the steel structure, are collided at a constant speed toward the reflector plate provided at a predetermined position, and the reflected grit and the shot are reflected. The maintenance coating method of the steel structure of any one of Claim 1 thru | or 3 including the process of classifying this used grit and this used shot based on the difference in the rebounding distance. The grit and / or the shot is made of stainless steel,
The used grit made of stainless steel and / or the used shot made of stainless steel that is sprayed on the steel structure is collected, and the collected used grit and / or the collected used shot is collected. A salt washing step of washing to remove salt attached to the surface of the used grit and / or the used shot;
The maintenance of the steel structure according to any one of claims 1 to 4, further comprising: a drying step of drying the washed used grit and / or the washed used shot after the salt washing step. Painting method. It is a circulation type blasting device used for the maintenance painting method of the steel structure according to claim 4,
The used grit and the used shot that are mixed and used by spraying on the steel structure, and a dust suction means for sucking dust including at least the release coating film generated in step A, and A separation chamber into which dust sucked by the dust suction means is introduced,
In the separation chamber, a flow path in which the dust sucked by the dust suction means moves along the air flow is formed, and the reflection plate is disposed on the downstream side of the flow path,
The separation chamber further includes a used grit collection unit that collects used grit that is reflected in the reflection plate by moving in the flow path, and a used shot that is reflected in the reflection plate after moving in the flow path. A circulating blasting apparatus comprising: a used shot collecting unit for collecting; and a peeling coating film collecting unit for collecting a peeling coating film floating in the flow path by air flow by the dust suction means . A circulating blasting device used in the maintenance painting method for steel structure according to claim 5,
Dust suction means for sucking dust including at least the used grit and the used shot that are mixed and used and injected to the steel structure, and dust sucked by the dust suction means are introduced. A separation room,
The separation chamber is formed with a flow path in which the dust sucked by the dust suction means moves along the air flow,
Further, the separation chamber includes a used grit collection unit that collects used grit that moves in the flow path, and a used shot collection unit that collects used shots that move in the flow path,
Of the used grit and used shot collected in the used grit collecting unit and the used shot collecting unit, used grit made of stainless steel and / or used by spraying on the steel structure and / or A salt cleaning means for cleaning a used shot made of stainless steel to remove the used grit and / or salt adhering to the surface of the used shot;
Drying means for drying the used grit washed by the salt washing means and / or the washed used shot;
A circulation type blasting apparatus comprising:

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