JP3268401B2 - Method for manufacturing plated member for welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plated member for welding such as a welded joint having a plated layer formed on a skin surface excluding an end to be welded.

[0002]

2. Description of the Related Art Galvanized iron pipes are widely used as piping materials because of their low cost and excellent corrosion resistance.
For the connection, various construction methods such as connection by screwing, connection by mechanical structure, connection by grooving, and connection by welding are adopted. And among the galvanized iron tubes, what is commonly called "white tube" is manufactured through a process A schematically shown in FIG.

[0003] That is, after the pickling and the flux treatment are applied to the tubular rough material of the pipe-formed iron base, the temperature is increased to about 430 (about 430).
To 480 ° C.) by dipping (plating bath immersion) in a plating bath in which molten zinc is stored to form a plating layer having a thickness of 0.2 to 0.5 mm made of an iron-zinc alloy layer. It is manufactured by pulling it out from the water and cooling it with water. The white pipe is frequently used as a pipe material for water supply or gas. Plated joints such as elbows, chis, sockets, and reducers in which the cylindrical coarse material is iron are also manufactured through the same process.

Meanwhile, a plated grooved welded joint in which one end is joined by a grooving method and the other end is joined by welding is a tube made of a pipe-formed iron base before a plating layer is formed. A groove is formed on one end of the coarse material by a dedicated machine to form a concave groove into which the coupling claw is fitted, and the above-described step A is performed on the cylindrical coarse material to form a zinc-based plating layer. It was done. As shown in FIG. 8, the other end of the grooved welded joint (plating member for welding) having such a plating layer is formed by grinding the surface of the groove before welding to form the other end of the welded portion. Removal of the plating layer (grinding of the groove).

[0005] Originally, the end of a member such as a welded joint to be welded should be cleaned by removing rust, black scale, paint, etc. before welding. It is not only difficult to completely remove the plating layer even if the member having the system plating layer is ground using a sander or a file, and when such a grinding operation is performed, The working environment is extremely deteriorated by the dust generated by heavy metal-containing fumes. With the recent lack of skilled technicians in the plumbing method,
Although a method of manufacturing unit parts at a factory and assembling them on site has been promoted, even if the above-described grinding work is performed at the factory, deterioration of the working environment cannot be avoided.

[0006] When the end of the member whose plating layer is not completely removed is welded, zinc vapor is sealed in the welded portion, and serious defects such as blowholes (pores) may occur. Even in the case of the grooved welded joint, even if grinding for removing the plating layer is performed, it is particularly difficult to remove the plating layer on the inner surface. If a blowhole is present in the welded portion, the welding will be defective and cause fluid leakage from the welded portion.

Therefore, the applicant of the present application has previously proposed a method of manufacturing a plated member for welding through the process shown in FIG. 9, and has tried to eliminate the need to grind a portion to be welded before welding.

In this method, after pickling and fluxing a cylindrical coarse material, a liquid material or a mud-like material containing an inorganic component is adhered to an end of the cylindrical coarse material, which is a welded portion, to form a mask. The grooved portion is masked to form a layer, and the thus-masked cylindrical coarse material is immersed in a plating bath (plating bath immersion) to form a plating layer on the skin surface of the cylindrical coarse material. Thereafter, the masking of the cylindrical coarse material on which the plating layer is formed is removed (mask removal).

Further, in the step shown in FIG. 9, it has been attempted to perform the groove masking using an epoxy-based masking agent.

[0010]

However, the following unreasonable points have been found in the manufacturing method which has been proposed by the applicant of the present invention through the process shown in FIG. In other words, in this method, the groove portion masking is a step performed after pickling and fluxing the cylindrical coarse material, and since the mud is used as a masking agent, the cylindrical coarse material is masked. Since it is necessary to dry the mud attached to the end of the material, it is unreasonable that it is necessary to secure a place for drying the mud, and there are various corrosive gases (oxidizing Gas) is filled, and the cylindrical material subjected to the flux treatment is exposed to the oxidizing gas atmosphere for a long time until the mud is dried.
It has been found that this may have an adverse effect on the soundness of a plating layer formed in a later step.
In addition, since the masking agent is a mud, there is another problem that the masking agent is easily peeled off or dropped off by impact.

On the other hand, regarding the above-mentioned method of performing the groove masking using an epoxy-based masking agent,
Once the masking agent has dried, it has the advantage of being able to withstand rough handling, but on the other hand, it requires two coats of the masking agent, and requires a long period of 8 hours for air drying after each application. Since it is required that the masking agent must be handled so as not to cause dripping after application, the step of masking the groove shown in FIG. 9 becomes a stagnation in performing all the steps shown in FIG. There was a point. In addition, when plating is performed by immersing the masked cylindrical material in a plating bath, the masking agent is burned off at that time, so that an expensive masking agent can be used only once. There was also.

The present invention has been made in view of the above circumstances and problems, and does not have the disadvantage of the conventional method described with reference to FIG. 8 in that a portion to be welded must be ground before welding. Of course, an object of the present invention is to provide a method for manufacturing a welded plated member that does not have the unreasonable points and problems described above with reference to FIG.

[0013] That is, the invention of claim 1 has been made by paying attention to the fact that the oxide film necessarily provided on the surface of the cylindrical coarse material has a property of inhibiting the formation of a plating layer. A welding plating member that simply adds a step of attaching a masking member to a cylindrical coarse material and a step of removing the same during a general ordinary plating step of performing pickling, flux treatment, and plating bath immersion. It is an object of the present invention to provide a production method of

[0014] According to a second aspect of the invention, it is possible to use a thermoplastic resin which is inexpensive plastic in comparison with the epoxy resin, also attached thermoplastic resin is against the cylindrical coarse material in the molten state In addition, the thermoplastic resin is burned out at high temperatures and generates gas, and has the property of forming a carbonized film on the surface of the cylindrical coarse material. It is an object of the present invention to provide a method for manufacturing a welded plating member, in which a fusion resin layer is masked on the end of a cylindrical coarse material before performing a normal plating process.

[0015]

According to a first aspect of the present invention, there is provided a method for manufacturing a plated member for welding, comprising: attaching a masking member to a welded end of a cylindrical member having an oxide film on the entire surface; Only the end face of the end and the inner and outer surfaces are masked, and the masked cylindrical coarse material is subjected to pickling and flux treatment.Then, the masking member is removed and the cylindrical coarse material is plated. It is immersion.

According to a second aspect of the present invention, there is provided a method of manufacturing a plated member for welding, wherein the welded end of a cylindrical coarse material heated to a melting temperature of a masking agent comprising a plastic powder is immersed in the powder. The plastic is melt-adhered to the above-mentioned end, so that the end surface of the welded end of the tubular coarse material and the inner and outer surfaces are masked with a fusion resin layer, and the masked tubular coarse material is subjected to acid treatment. after the washing and fluxed, performs immersion in the plating bath, the plug
Species that burn off as sticks depending on the temperature of the plating bath
It is to use a kind of thing .

[0017]

According to the first aspect of the present invention, the end surface of the end portion of the cylindrical coarse material masked by the masking member and the oxide film on the inner and outer surfaces remain as they are without being activated even after being subjected to pickling and flux treatment. Therefore, even when the cylindrical coarse material from which the masking member has been removed is immersed in the plating bath, no plating layer is formed on the end face of the masked cylindrical coarse material and on the inner and outer surfaces.

According to the second aspect of the present invention, when the cylindrical crude material whose end is masked by the fusion resin layer is immersed in the plating bath, the plating bath is at a high temperature and the masking is formed by the plastic fusion resin layer. The generation of gas accompanying the burning of plastic and the formation of a carbonized film are synergistic,
The formation of the plating layer on the end face of the end portion of the masked cylindrical coarse material and the inner and outer surfaces is prevented.

[0019]

1 is a schematic process diagram showing a method for manufacturing a plated member for welding according to an embodiment of the present invention. According to the manufacturing method of this embodiment, a masking member is attached to an end (for example, a groove) to be welded of a cylindrical coarse material made of iron base having an oxide film on the entire surface, and the end surface of the end and the inside and outside of the end are formed. A groove-masking step of masking only the surface of the metal, a pickling step of pickling the masked cylindrical coarse material, a flux treatment step performed after the pickling step, and a flux treatment step. The method includes a mask removing step of removing the masking member from the passed cylindrical coarse material, and a plating bath dipping step of dipping the cylindrical member from which the masking member has been removed in a plating bath.

The oxide film provided on the cylindrical rough material is formed by iron oxide generated during hot forging or molding, or 300 to 500 when the primary rust-preventive coating film is mechanically peeled off by shot blasting. It is formed by oxidizing the surface by heating in air at about 30 ° C. for about 30 minutes, and is necessarily provided on the entire surface of the cylindrical coarse material.

FIG. 2 shows masking used for masking.
Partially cutaway side view of the member 5, FIG. 3 is the masking member 5
Shows the usage state of the. As shown in FIG. 2, the masking member 5 is constituted by an annular member having an annular groove 6 inserted into the welded end portion 2 of the cylindrical coarse material 1, and the inner peripheral groove wall surface of the groove 6. 61 and the outer circumferential groove wall surface 62 are formed as curved surfaces protruding so that their axial central portions approach each other. Note that both the inner peripheral side wall surface 61 and the outer peripheral side wall surface 62 of the groove 6 may be formed flat, and a projection having a semicircular cross section may be provided on the wall surfaces 61 and 62 so as to face each other. The inner peripheral groove wall surface 61 and the outer peripheral groove wall surface 6
2, the distance between at least the closest points is shorter than the wall thickness of the welded end 2 of the cylindrical member 1 indicated by a virtual line. The masking member 5 is made of a material having excellent heat resistance, acid resistance and elasticity, for example, silicone rubber.

The groove-masking step is completed only by performing a simple operation of inserting the groove 6 of the masking member 5 into the welded end 2 of the cylindrical member 1 as shown in FIG. In this case, the wall surface 6 of the groove 6 in the masking member 5
It is desirable that the end surfaces 21 and the inner and outer surfaces 22 and 2 should be securely adhered to the end surface 21 and the inner and outer surfaces 22 and 23 of the end portion 2 of the cylindrical coarse material 1.
When it is difficult to obtain such a secure contact state due to the unevenness of the groove 3, the wall 6 of the groove 6 in the masking member 5
A general viscous oil L such as grease is preferably applied to the first and second 62 in advance. By doing so, even if the end surface 21 and the inner and outer surfaces 22 and 23 have irregularities, the surfaces 21, 22 and 23 and the groove 6 in the masking member 5
The gaps between the wall surfaces 61, 62 and the like are filled with the viscous fat L, so that the end face 21 and the inner and outer surfaces 22, 23 do not need to be pickled at all in the pickling step which is a subsequent step. 24 is a groove surface.

The pickling step is a step of activating the surface of the cylindrical coarse material by removing a substance obstructing the plating such as an oxide film formed on the surface of the cylindrical coarse material.
In this pickling step, the masked cylindrical coarse material at the end is processed, so that the end face of the masked end and the inner and outer surfaces of the cylindrical coarse material remain without being activated.

The flux treatment step is a step in which the flux is adhered to the surface of the cylindrical coarse material activated in the pickling step. In this flux treatment step, the cylindrical coarse material whose end is masked is also treated. Therefore, no flux adheres to the masked end surface and the inner and outer surfaces of the cylindrical coarse material.

The mask removing step is completed by a simple operation of simply removing the masking member 5 attached to the end 2 of the tubular member 1 as shown in FIG. In the cylindrical crude material 1 from which the masking member 5 has been removed in this step, the end face 21 of the masked end portion 2 and the inner and outer surfaces 22, 23 have been masked.
Since the oxide film and other substances that hinder plating are left as they are, the surfaces 21, 22, 2
3 is inactive.

In the plating bath immersion step, the cylindrical member from which the masking member has been removed is immersed in a plating bath containing molten zinc at a high temperature of about 430 to 480 ° C., and the iron-zinc alloy layer having a thickness of 0.2 mm is formed. A plating layer having a thickness of about 0.5 mm is formed, pulled up from the plating bath, and cooled (for example, water-cooled). In this plating bath immersion step, a plating layer is formed only on the surface of the cylindrical coarse material activated and flux adhered in the pickling step, and the end face of the masked end of the cylindrical coarse material and the inner and outer surfaces are formed. No plating layer is formed on the surface.

FIG. 4 shows a usage state of the masking member 5 according to the modification. The masking member 5 is divided into an inner member 7 and an outer member 8, and the inner member 7 and the outer member 8 are fitted to each other to insert the groove into the welded end 2 of the cylindrical coarse member 1. 6 are formed. Then, the inner peripheral side wall surface 6 of the groove 6
A number of annular projections 71 are provided on the outer peripheral surface of the inner member 7 corresponding to 1 and a number of annular projections 72 are also provided on the inner peripheral surface of the outer member 8 corresponding to the outer peripheral side wall surface 62 of the groove 6. The projections 71 and 72 are in close contact with the inner and outer surfaces 22 and 23 at the end 2. Note that the inner member 7 and the outer member 8 are made of a material having excellent heat resistance, acid resistance, and elasticity, such as silicon rubber, and that the wall surfaces 61 and 62 of the groove 6 have a general property such as grease. It is the same as described above in that if the viscous fat L is applied in advance, the end face 21 of the end portion 2 and the inner and outer surfaces 22, 23 do not need to be pickled at all in the pickling step.

FIG. 5 is a schematic process diagram showing a method of manufacturing a plated member for welding according to an embodiment of the present invention. In the manufacturing method of this embodiment, a plastic powder made of a thermoplastic resin is used as a masking agent, and the welded end (for example, a groove) of the cylindrical coarse material heated to the melting temperature of the masking agent is formed as described above. A groove masking step of masking the fused resin layer on the end face and the inner and outer surfaces of the welded end of the cylindrical coarse material by immersing the thermoplastic resin in the powder and fusing the thermoplastic resin to the end. A pickling step of pickling the masked cylindrical coarse material, a flux treatment step performed after the pickling step, and a plating bath of dipping the masked cylindrical member into a plating bath. Dipping step.

In the groove masking step, the welded end of the heated cylindrical coarse material is immersed in the thermoplastic resin powder, so that the thermoplastic resin powder is heated by the cylindrical coarse material. Then, as shown in FIG. 6, it adheres to the end 2 to form a fusion resin layer 9 and masks the end face 21 of the end 2 and the inner and outer surfaces 22, 23.

In the pickling process, the masked cylindrical member at the end is processed, so that the end surface of the masked end and the inner and outer surfaces of the cylindrical member remain without being activated. Also in the flux processing step, the masked cylindrical coarse material at the end is processed, so that the flux does not adhere to the end face of the masked end and the inner and outer surfaces of the cylindrical coarse material.

In the plating bath immersion step, the cylindrical member whose end is masked is immersed in a plating bath containing molten zinc at a high temperature of about 430 to 480 ° C., so that the fusion resin layer used for masking is The burning of the gas and the formation of a carbonized film on the end surface of the cylindrical coarse material are synergistic, resulting in plating of the end surface of the masked cylindrical coarse material and the inner and outer surfaces. Layer formation is prevented. Therefore, the plating layer is formed only on the portion of the surface of the cylindrical coarse material that has not been masked. The cylindrical coarse material pulled up from the plating bath is cooled (for example, water-cooled). In addition,
Using a vinyl chloride resin as the thermoplastic resin
It is not preferable because toxic chlorine gas is generated when the fused resin layer is burned out.

In the method according to each of the embodiments described above, the molten zinc is used as the plating bath. However, all the plating baths, which are used to store industrially used plating metals such as aluminum in a molten state, are described. Is included in the production method of the present invention. In addition, in the manufacturing method of the present invention, the ends of grooved or non-grooved welded joints such as tees and sockets, joints and reducers to which a method other than the grooving method is applied, and even pipes are welded. All of the plated parts for welding .

FIG. 7 is a partially cutaway side view of the plating member for welding 10 manufactured by carrying out the invention of claim 1 or 2, and also shows an enlarged view of a portion X in the same figure. I have. The plating member for welding 10 has a concave groove 20 joined at one end by a grooving method, and an elbow having a groove (corresponding to the end 2 to be welded) joined at the other end by welding. Shaped grooved welded joint. In the groove portion which is the end portion 2 to be welded, the end surface 21, the inner surface 22, and the outer surface 2 of the iron-made cylindrical coarse material 1 are formed.
3 are exposed. Further, a zinc-based plating layer 50 is formed on the skin end face on one end side of the cylindrical coarse material 1 excluding the end 2 and on the inner and outer skin surfaces.

According to such a plating member 10 for welding, the surface of the groove portion has an end face 21 and inner and outer surfaces 22, 23.
Are all on the skin surface of the cylindrical coarse material 1, so that welding is performed only on the skin surface of the cylindrical coarse material 1. Therefore, the welded portion has good welding quality without being affected by the plating layer. Further, since it is not necessary to grind the groove before welding, there is no room for deteriorating the working environment due to generation of dust.

[0035]

According to the first aspect of the present invention, since only a step of attaching / detaching a masking member to / from a cylindrical coarse material is added during a general ordinary plating step, a weld joint is formed without stagnation in the manufacturing process. Thus, there is an effect that a plating member for welding can be easily and efficiently manufactured. In addition, since a method of attaching a masking member and masking the end of the cylindrical coarse material is adopted, use a masking member made of a material such as silicon rubber that can withstand rough handling. Is possible.

According to the second aspect of the present invention, there is provided a manufacturing process by simply adding a simple and inexpensive process of masking the end of a cylindrical coarse material using plastic before performing a general ordinary plating process. There is an effect that a plating member for welding such as a welded joint can be easily and efficiently manufactured without forming stagnation.

Since the welded plated members manufactured according to these inventions do not need to grind the welded ends before welding, there is no room for deteriorating the working environment due to generation of dust. The plating layer does not have any adverse effect.

[Brief description of the drawings]

FIG. 1 is a schematic process diagram showing a method of manufacturing a plated member for welding according to an embodiment of the present invention.

FIG. 2 is a partially cutaway side view of a masking member used for masking.

FIG. 3 is a partially cutaway side view showing a use state of the masking.

FIG. 4 is a partially cutaway side view showing a usage state of a masking member according to a modification.

FIG. 5 is a schematic process diagram showing a method for manufacturing a plated member for welding according to an embodiment of the second invention.

FIG. 6 is a partially cutaway side view showing a main part of a cylindrical coarse material having undergone a groove masking step according to an embodiment of the second invention.

FIG. 7 is a partially cutaway side view of a plating member for welding manufactured by carrying out the invention of claim 1 or 2;

FIG. 8 is a process diagram schematically illustrating a conventional method of manufacturing a plated member for welding through a general plating process.

FIG. 9 is a process diagram schematically showing a method of manufacturing a plated member for welding according to a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical coarse material 2 End to which cylindrical coarse material is welded 5 Masking member 9 Fused resin layer layer 21 End edge to be welded 22, 23 Inner and outer surfaces of edge to be welded

Continuation of the front page (51) Int.Cl. ⁷ identification code FI F16L 13/02 F16L 13/02 (58) Investigated field (Int.Cl. ⁷ , DB name) C23C 2/38 B23K 9/23 B23K 31 / 00 C23C 2/02 C23C 2/06 F16L 13/02

Claims (2)

(57) [Claims] 1. A masking member is attached to an end to be welded of a cylindrical crude material having an oxide film on the entire surface, and masking is performed only on the end face and inner and outer surfaces of the end, and the masking is performed. A method for manufacturing a plated member for welding, comprising: after performing pickling and flux treatment on a cylindrical coarse material, removing the masking member, and immersing the cylindrical coarse material in a plating bath. 2. A cylinder, which is formed by immersing a welded end of a cylindrical coarse material heated to a melting temperature of a masking agent made of a plastic powder into the powder and melting and adhering the plastic to the end. The fused resin layer is masked on the end face of the welded end and the inner and outer surfaces of the coarse material, and the masked cylindrical coarse material is subjected to pickling and flux treatment, and then to a plating bath. Do soaking and over
Burned out due to the temperature of the above plating bath as plastic
A method for producing a plated member for welding, characterized by using a material of the following type .