JP2015063738A - Arc welding method and arc welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc welding method and an arc welding apparatus which can form a splay metal film having excellent anticorrosion property on a splay target object, compared to compressed air normally used.SOLUTION: A compressed gas containing nitrogen gas as a main component is used as a compressed gas used for splaying molten metal onto a splay target object 4.

Description

  The present invention relates to an arc spraying method and apparatus, in particular, a sprayed metal having excellent anticorrosion properties by using a compressed gas mainly composed of nitrogen gas as a compressed gas used for spraying a molten metal onto an object to be sprayed. The present invention relates to an arc spraying method and apparatus capable of forming a coating on an object to be sprayed.

  For example, as shown in the schematic diagram of FIG. 3, the arc spraying apparatus generates an arc by applying a voltage between two spraying wires 22 a and 22 b continuously fed to the spraying gun 21, thereby generating an arc. The molten metal composed of the molten spray wires 22a and 22b is put on the compressed air 23 that has flowed out through the spray gun 21 and sprayed onto the spray object 24, thus forming the spray metal film 25 on the spray object 24. It is.

  Patent Document 1 discloses a technique for forming a sprayed metal film by arc spraying on the surface of a pipe constituent member such as a cast iron, an iron metal tube, or a valve as an object to be sprayed for the purpose of corrosion protection.

  In this prior art, a metal film is formed on the surface of an object to be sprayed by a spray wire made of zinc and a spray wire made of an aluminum-magnesium alloy. According to this prior art, the anticorrosion performance excellent compared with the conventional spray metal coating only of zinc is obtained.

JP 2012-97348 A

  However, the compressed air 23 used for spraying the metal melted in the spray gun 21 onto the object 24 to be sprayed oxidizes the molten metal because it contains oxygen. As a result, this contributes to a decrease in the anticorrosion performance of an active metal or alloy having anticorrosion performance. In addition, even in a pipe component having an outer surface anticorrosive coating, the original high anticorrosion performance may not be maintained for a long time.

  Therefore, the object of the present invention is to use a compressed gas mainly composed of nitrogen gas as a compressed gas used for spraying the molten metal onto the object to be sprayed, thereby achieving high activity without oxidizing the molten metal. An object of the present invention is to provide an arc spraying method and apparatus capable of forming a sprayed metal film having excellent anticorrosion properties on an object to be sprayed.

  The inventor of the present application has made extensive studies in order to achieve the above object. As a result, if a compressed gas mainly composed of nitrogen gas is used as the compressed gas used for spraying the metal melted in the spray gun, a sprayed metal film having excellent corrosion resistance is formed on the object to be sprayed. The knowledge that it was possible was acquired.

  Moreover, as a compressed gas, the knowledge that nitrogen gas whose nitrogen content is 90 volume% or more was preferable was acquired.

  The present invention has been made on the basis of the above findings, and is characterized by the following.

  The invention described in claim 1 is characterized in that a compressed gas containing nitrogen gas as a main component is used as the compressed gas used for spraying the molten metal onto the object to be sprayed.

  The invention described in claim 2 is characterized in that, in the invention described in claim 1, compressed nitrogen gas having a nitrogen content of 90% by volume or more is used as the compressed gas.

  The invention described in claim 3 is characterized in that it includes a compressed gas supply source mainly composed of nitrogen gas, which is used for spraying molten metal onto an object to be sprayed.

  The invention described in claim 4 is characterized in that, in the invention described in claim 3, the compressed gas is a compressed nitrogen gas having a nitrogen content of 90% by volume or more.

  According to this invention, as a compressed gas used for spraying the molten metal on the object to be sprayed, a compressed gas mainly composed of nitrogen gas is used, so that the molten metal is hardly oxidized and is in an active state. Can be sprayed. As a result, the production of metal oxide in the sprayed metal film is suppressed, so that a sprayed metal film having excellent anticorrosion properties can be formed on the object to be sprayed as compared with compressed air that is usually used.

  Further, according to the present invention, by using a compressed gas mainly composed of nitrogen gas as a compressed gas used for spraying the molten metal onto the object to be sprayed, pores formed in the sprayed metal film are formed. Can be reduced.

It is a schematic block diagram which shows the arc spraying apparatus of this invention. It is process drawing in the case of manufacturing the cast iron pipe by which the arc spraying method of this invention was applied and the outer surface anticorrosion coating was performed. It is sectional drawing which shows the spray gun of an arc spraying apparatus.

  Next, an embodiment of the arc spraying apparatus of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an arc spraying apparatus of the present invention.

  In FIG. 1, 1 is an arc spraying device main body, 2 is a spray gun, 3 is a compressed gas supply source mainly composed of nitrogen gas, and 4 is a pipeline structure made of cast iron, for example, as an object to be sprayed. It is a member. The compressed gas supply source 3 includes a nitrogen gas supply device 7 including a compressor 5 and an oxygen separation tank 6 and a refrigeration dehumidifier 8.

  The compressed gas 9 (see FIG. 3) mainly containing nitrogen gas from the compressed gas supply source 3 passes through the compressed gas pipe 10 and the arc spraying device main body 1 together with the two spraying wires 11a and 11b. Supplied to the spray gun 2. As the compressed gas 9, it is preferable to use a compressed nitrogen gas having a nitrogen content of 90% by volume or more. In the thermal spray gun 2, the thermal spray wires 11 a and 11 b are melted by an arc generated between the two thermal spray wires 11 a and 11 b, and the molten metal rides on the compressed gas 9 containing nitrogen gas as a main component and is tubed. The spraying member 4 is sprayed, and thus the sprayed metal coating 12 is formed on the conduit member 4.

  According to the arc spraying apparatus of the present invention, the molten metal is almost oxidized by using the compressed gas mainly composed of nitrogen gas as the compressed gas 9 used for spraying the molten metal onto the pipe line constituent member 4. And can be sprayed in an active state. As a result, the formation of metal oxide in the sprayed metal film 12 is suppressed, so that the sprayed metal film 12 having excellent corrosion resistance is usually formed on the pipe member 4 as compared with the compressed air used. be able to.

  In addition, since the voids formed in the sprayed metal film 12 can be reduced, the strength of the sprayed metal film 12 can be increased.

  In addition, since the sprayed metal film 12 having excellent corrosion resistance can be formed on the pipe constituent member 4, the film thickness of the sprayed metal film 12 can be reduced if the same degree of corrosion resistance is sufficient. it can. Therefore, the cost can be reduced accordingly.

  If the above-mentioned sprayed wire made of zinc and the sprayed wire made of an aluminum-magnesium alloy are used as the sprayed wires 11a and 11b, the sprayed metal film 12 having a further excellent corrosion resistance is used as a pipe. The component member 4 can be formed.

Example 1
Next, the present invention will be further described by way of example with reference to FIG.

  Rust and oxide scale were removed from the outer surface of the ductile cast iron pipe by blasting the outer surface of the ductile cast iron pipe having a diameter of 100 mm, a wall thickness of 7.5 mm, and a length of 700 mm by grit blasting.

Next, on the outer surface of the surface-treated ductile cast iron pipe, using an automatic arc spraying apparatus, a spray wire composed of zinc and aluminum containing 5 wt% magnesium so that the amount of spray coating becomes 250 g / m ^2- Using a sprayed wire made of a magnesium alloy, arc spraying was performed with a compressed nitrogen gas stream having a nitrogen content of 90% by volume to form a pseudoalloy sprayed metal coating.

  Thus, the cast iron pipe which gave the thermal spray metal film which consists of zinc and an aluminum magnesium alloy was manufactured.

(Comparative Example 1)
As in the above example, an outer surface automatic arc spraying apparatus is used on the outer surface of a ductile cast iron pipe having a surface finish of caliber φ100 mm, wall thickness 7.5 mm, and length 700 mm. Using a spray wire made of zinc and a spray wire made of an aluminum-magnesium alloy containing 5 wt% magnesium so as to be / m ² , arc spraying was performed with a compressed air stream to form a pseudoalloy sprayed metal film. .

  And with respect to the said Example 1 and the said comparative example 1, the state and the oxygen content of the void | hole of the sprayed metal film cross section were investigated by SEM (scanning electron microscope). As a result, the sprayed metal coating of Example 1 that was arc sprayed with a compressed nitrogen gas stream had fewer pores than the sprayed metal film of Example 2 that was arc sprayed with a compressed air stream, It was also found that almost no oxygen reacted with the sprayed metal.

(Example 2)
In the same manner as in Example 1, an outer surface automatic arc spraying device was used on the outer surface of a ductile cast iron pipe having a diameter of φ100 mm, a wall thickness of 7.5 mm, and a length of 700 mm that had been subjected to a surface finishing treatment. Arc spraying is performed with a compressed nitrogen gas stream having a nitrogen content of 90% by volume using a spray wire made of zinc and a spray wire made of an aluminum-magnesium alloy containing 5 wt% magnesium so as to be / m ^2. A pseudo-alloy sprayed metal coating was formed.

Next, after the ductile cast iron pipe formed with the pseudoalloy sprayed metal film in this way is placed in a heating furnace and preheated to 80 ° C., phosphoric acid-modified epoxy resin and powdered silica are coated on the pseudoalloy sprayed metal film. Is coated with a sealing agent composed of an acrylic resin paint blended so as to have a film thickness of 10 μm, and a sealing treatment film is formed. Further, an aqueous epoxy-modified acrylic resin emulsion is formed on the sealing treatment film. The paint was applied so that the amount applied was 200 g / m ² and dried.

  In this way, an outer surface anticorrosion coated cast iron pipe coated with a sprayed metal film made of zinc and an aluminum-magnesium alloy, sealed, and further coated with a synthetic resin paint was manufactured.

(Comparative Example 2)
As in the above example, an outer surface automatic arc spraying apparatus is used on the outer surface of a ductile cast iron pipe having a surface finish of caliber φ100 mm, wall thickness 7.5 mm, and length 700 mm. Using a spray wire made of zinc and a spray wire made of an aluminum-magnesium alloy containing 5 wt% magnesium so as to be / m ² , arc spraying was performed with a compressed air stream to form a pseudoalloy sprayed metal film. .

Next, after the ductile cast iron pipe formed with the pseudoalloy sprayed metal film in this way is placed in a heating furnace and preheated to 80 ° C., phosphoric acid-modified epoxy resin and powdered silica are coated on the pseudoalloy sprayed metal film. Is coated with a sealing agent composed of an acrylic resin paint blended so as to have a film thickness of 10 μm, and a sealing treatment film is formed. Further, an aqueous epoxy-modified acrylic resin emulsion is formed on the sealing treatment film. The paint was applied so that the amount applied was 200 g / m ² and dried.

  Then, a combined cycle test was performed on Example 2 and Comparative Example 2.

  The test conditions are as follows.

Combined cycle test device: CPY-90 type, salt water spray test manufactured by Suga Test Instruments Co., Ltd., which satisfies the performance specified in JIS Z 2371.
Drying test:
(A) Temperature condition: (RT + 10 ° C.) to 70 ± 1 ° C.
(B) Humidity condition: 25 ± 5% rh at a temperature of 60 ° C.
Wet test (high temperature):
(A) Temperature conditions: (RT + 10 ° C.) to 50 ± 1 ° C.
(B) Humidity condition: 95% rh or more at a temperature of 50 ° C. Outside air introduction test: About outside air temperature / temperature / humidity control Test cycle: Cycle A in Annex C (normative) of JIS K 5600-7-9
Number of test cycles: Number of cycles until the natural potential reaches the anticorrosion potential (-750 mV)

  The combined cycle test results are shown in Table 1.

  As is clear from Table 1, according to the ductile cast iron pipe with the outer surface anticorrosion coating produced by the arc spraying apparatus of the present invention, it was sprayed in a compressed air stream by spraying in a compressed nitrogen gas stream ( It was confirmed that the period of maintaining the anticorrosion performance was longer than that of Comparative Example 2).

  From this, it was found that the anticorrosion performance of the outer surface anticorrosion coating tube can be obtained with the above-mentioned conventional technology while the anticorrosion performance for a longer period can be obtained.

1: Arc spraying device main body 2: Spraying gun 3: Compressed gas supply source 4: Pipeline component 5: Compressor 6: Oxygen separation tank 7: Nitrogen gas supply device 8: Refrigeration dehumidifier 9: Compressed gas 10: Compressed gas Supply piping 11a, 11b: Thermal spray wire 12: Thermal spray metal coating 21: Thermal spray gun 22a, 22b: Thermal spray wire 23: Compressed air 24: Thermal spray object 25: Thermal spray metal coating

Claims (4)

  An arc spraying method characterized in that a compressed gas containing nitrogen gas as a main component is used as a compressed gas used for spraying molten metal onto an object to be sprayed.   The arc spraying method according to claim 1, wherein compressed nitrogen gas having a nitrogen content of 90% by volume or more is used as the compressed gas.   An arc spraying apparatus comprising a supply source of compressed gas mainly containing nitrogen gas, which is used for spraying molten metal onto an object to be sprayed.   The arc spray apparatus according to claim 3, wherein the compressed gas is a compressed nitrogen gas having a nitrogen content of 90% by volume or more.

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