JP2000005817A - Multi-wound stainless steel pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-wound stainless steel pipe of high quality which is superior in pressure resistance and strength in being processed. SOLUTION: This steel pipe is made by plastic deforming a hoop material composed of stainless steel sheet, wherein a brazing filler metal is applied on the surface into a pipe, melting the filler metal between the walls of the multi-wound pipe, and then cooling the molten filler metal. In this case, the stainless steel sheet, wherein Ni plating of 0.1 μm in thickness is applied on the surface and Cu plating of 4-8 μm in thickness is applied on it so as to secure 75% or more of Cu concentration in the brazing filler metal after the brazing is used as the hoop material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-turn stainless steel pipe manufactured by winding a hoop material made of a stainless steel plate and brazing the same.

[0002]

2. Description of the Related Art Generally, a multi-turn metal pipe is formed by plastically deforming a hoop material (metal strip) having a brazing material on its surface into a pipe by a molding device, and the multi-turn pipe is placed between walls. After the material is melted by the heating device, the melted brazing material is solidified by the cooling device to produce a product. Multi-turn stainless steel pipes are also generally manufactured using stainless steel sheets with copper plating directly on the surface as hoop material, but a Ni plating layer is interposed between the stainless steel sheet surface and the copper plating. A multi-turn stainless steel pipe using a stainless steel sheet which has been made to roll is also known.

[0003]

However, the conventional multi-turn stainless steel pipe has the following problems. When Cu plating is applied directly to the surface of a stainless steel plate, the adhesion between the stainless steel plate and Cu is weak, and there is a drawback in that sufficient pressure resistance and work strength cannot be obtained when the product is made into a multi-turn tube. Was. When an Ni plating layer is interposed between the surface of the stainless steel plate and the Cu plating, the adhesion in the plate state can be obtained, but the Ni component of the stainless steel base material in the brazing temperature range after multiple winding forming is obtained. And Ni plating components are alloyed with Cu so that the Ni concentration becomes extremely high, and as a result, the ductility of the brazing filler metal is reduced. There was a problem that it could not be secured.

The present invention has been made to solve the problems of the conventional multi-roll stainless steel pipe, and aims to provide a high-quality multi-roll stainless steel pipe having excellent pressure resistance and work strength. Things.

[0005]

A multi-turn metal pipe according to the present invention is obtained by plastically deforming a hoop material made of a stainless steel plate having a brazing material on its surface into a pipe, and forming a gap between the walls of the multi-turn pipe. A multi-turn stainless steel pipe produced by melting a brazing material and then cooling the molten brazing material, and has a thickness of 0.1 μm or less, preferably 0.05 μm, on the surface as a hoop material.
a stainless steel plate having a thickness of 4 to 8 μm and a Ni plating of m to 0.1 μm, and further having a Cu plating of a thickness of 4 to 8 μm so as to secure a Cu concentration of 75% or more in the brazing material after brazing. It is characterized by the following.

In the present invention, the surface of the stainless steel base material is directly plated with Ni having a thickness of 0.1 μm or less, and further has a thickness of 4 to 4 mm so as to secure a Cu concentration of 75% or more in the brazing material after brazing. The 8 μm Cu plating
This is to have a role as a binder for increasing the adhesion between the stainless steel base material and the copper brazing material. In this case, since the plating layer provided on the surface of the stainless steel base material becomes an alloy layer of Ni and Cu, it is necessary to consider the Cu concentration in the brazing material made of this alloy layer. That is, if the content of the Ni component in the brazing material is large, the strength (ductility, etc.) of the brazing material is reduced, and the brazing material is cracked or peeled off at the time of end processing or the like. In the case of brazing filler metal,
It is necessary to make the Cu concentration necessary to prevent a decrease in the strength (eg, ductility) of the brazing material. According to experiments performed by the present inventors, it has been found that, in the case of a brazing material made of an alloy layer of Ni and Cu, the Cu concentration in the brazing material after brazing is preferably 75% or more. That is, in the case of a brazing material composed of an alloy layer of Ni and Cu, when the Cu concentration in the brazing material after brazing is less than 75%, the content of the Ni component in the brazing material increases, and the ductility of the brazing material is increased. It was found that the strength was reduced. Therefore, in order to prevent a reduction in strength such as ductility of the brazing material, the Cu concentration in the brazing material after brazing is reduced to 7%.
It is necessary to maintain the thickness ratio of Ni and Cu at the time of plating on the stainless steel base material so that 5% or more can be secured. In order to maintain the thickness ratio, the present invention sets the Ni plating film thickness to 0.1 μm or less, The plating film thickness was limited to 4 to 8 μm. The reason is that if the thickness of the Ni plating film directly applied to the surface of the stainless steel base material exceeds 0.1 μm, not only the adhesion force between the stainless steel base material and the copper brazing material decreases, but also the brazing material after brazing. This is because the Ni component in the steel is increased and the ductility of the brazing material is reduced, so that the pressure resistance and the work strength cannot be obtained. The reason why the thickness of the Cu plating film applied on the Ni plating film was 4 to 8 μm was 4 μm
If it is less than Ni, the Ni of the SUS base material may diffuse after the brazing and the Cu concentration may be lower than 75%. This is because the above looks worse.

[0007] As a method of manufacturing a multi-turn stainless steel pipe according to the present invention, a hoop material is plastically deformed into a pipe by a forming apparatus, and a brazing material between the walls of the multi-turn pipe is supplied to a heating apparatus. When in the molten state, the tube is pressed uniformly from the inside or outside in the radial direction, or the tube is pulled in the axial direction so that the multiple winding walls are pressed against each other, and then the cooling device And a method of solidifying and commercializing the product. The above-mentioned forming apparatus is generally configured such that a hoop material guide roll, a forming roll for forming into multiple windings, and a finishing shaping roll are sequentially arranged, and a rod with a swimmer is further arranged from the hoop material guide roll side. is there. Here, to apply a pressing force uniformly to the multiple wound pipe body from the inside or outside in the radial direction, or to apply the tensile force in the axial direction by pulling the pipe body in the axial direction, The purpose of this is to minimize voids where no brazing layer is present and to improve the adhesion of the outer seam even if the hoop material has dimensional variations. As this means, for example, a method using a plug or a mechanical expansion head mounted on a pipe, a method using a pressing roll, or changing the transfer speed of the pipe to apply a tensile force in the pipe axis direction to the pipe. There is a method in which multiple walls are pressed against each other in the radial direction.

[0008] The multi-turn stainless steel pipe according to the present invention maintains the Cu concentration in the brazing material after brazing to such an extent that the strength (such as ductility) of the brazing material after commercialization does not decrease (75% or more). The strength between the multiple winding wall layers is obtained, and the pressure resistance strength and the work strength are excellent.

[0009]

FIG. 1 is a longitudinal sectional side view showing an enlarged part of a cross-sectional structure of a hoop material of a multi-turn stainless steel pipe according to the present invention, and FIG. 2 is an overall configuration of a multi-turn stainless steel pipe manufacturing apparatus according to the present invention. It is a schematic diagram showing an example. Here, a double wound stainless steel pipe will be described as an example.

As shown in FIG. 1, the hoop material of the double-wound stainless steel pipe according to the present invention is obtained by plating the entire surface of both surfaces of a stainless steel plate 1-1 with Ni to a Ni of 0.1 μm or less. The plating layer 1-2 is formed, and Cu plating is further performed thereon to form the Cu plating layer 1-3 having a thickness of 4 to 8 μm.

Next, an apparatus for manufacturing a double-wound stainless steel pipe using the hoop material will be described. The double winding forming apparatus 11 shown in FIG.
Roll 11-1, hoop material 1 for guiding the material to the forming process
Of a pair of tube-forming or forming rolls 11-2 and finish-setting rolls 11-3, which are formed from a plate shape into a double-wound tube, and a rod 11-with a swimmer from the guide roll 11-1 side. 4 is arranged.

The heating device 12 includes, for example, a plurality of current-carrying rolls (rotating electrodes) arranged at appropriate intervals in the line direction.
A resistance heating method according to 12-1 is adopted. The inside of the heating device is in a non-oxidizing atmosphere or a reducing gas atmosphere.

Further, a pressing roll 13 as a means for radially pressing the double-wound walls to each other presses the outer peripheral surface of the double-wound tube 15 formed by the forming device 11 from the outside in the radial direction. Since the brazing material between the walls of the double-wound tube 15 must be pressurized while the brazing material is in a molten state, the cooling device 1 is pressed from within the heating device 12.
4 entrance side.

The cooling device 14 is provided immediately after the heating device 12 and has a structure in which a number of refrigerant injection nozzles (not shown) are arranged so as to uniformly and quickly cool the outer periphery of the double wound tube 15. Has become. Specifically, for example, a cooling jacket type in which a number of nozzle holes are provided in the inner periphery is used, and a structure in which a refrigerant is blown from the nozzle holes to a double-wound tube passing therethrough is used. As the refrigerant, a gas such as a gas is mainly used, but a liquid such as water can also be used.

Further, as a primary cooling means for cooling the double wound tube body 15 as quickly as possible, a nozzle 16 is provided immediately after the pressing roll 13 for press-contact, and the nozzle is used to inject a coolant to thereby form a brazing filler metal. Can be rapidly cooled to around the freezing point.

As described above, the cooling device includes the nozzle 16
It is preferable that the cooling device 14 comprises a primary cooling means and a secondary cooling means comprising a cooling device 14 provided on the downstream side of the nozzle. The cooling of the wound tube body may be performed.

In the apparatus for manufacturing a multiple wound tube having the above-described structure, Ni plating is applied to the entire surface of both surfaces of the stainless steel plate 1-1 to form a Ni plating layer 1-2 having a thickness of 0.1 μm or less. The hoop material 1 on which a Cu plating layer 1-3 having a thickness of 4 to 8 μm is formed by performing Cu plating is unwound from an uncoiler (not shown) and formed into a tube 15 having a double wall by a multiple winding forming apparatus 11. And introduced into the heating device 12. In the heating device 12, current is supplied to the tube from the DC power supply via the plurality of current-carrying rolls 12-1, and the brazing material made of the Cu plating layer on the Ni plating layer between the walls is melted due to the resistance heating of the tube. I do.

Subsequently, in a state where the brazing material is molten, the multiple rolled tube is uniformly pressed from the outside in the radial direction by the pressing roll 13, and the walls of the multiple wound tube are pressed against each other in the radial direction by this pressing. Is done. At this time, since the brazing material between the walls is still in a molten state, the brazing material spreads between the walls due to the pressing action of the pressing roll 13, and voids where no brazing material is present are reduced or eliminated.

The double-wound tube 15 exiting the heating device 12 is cooled by the cooling device 14 so that the brazing material between the walls is completely solidified and brazing is completed. In addition, as the heating means of the multiple winding tube body, a high-frequency heating coil may be adopted instead of the above-described resistance heating method, or a general heating furnace may be used as a brazing furnace.

Although not shown, when a press roll is provided immediately after the heating device, one end side (seam portion side) of the outermost wall of the double-wound tube body is externally controlled by the press roll. Because it is forcibly pressed, it fits into and adheres to the inner wall, and peeling of the outer seam portion is prevented.

The double-wound stainless steel pipe of the present invention produced by the above-described apparatus can provide a copper layer having good adhesion without voids and no brazing material between the walls. It goes without saying that the same applies to multi-turn stainless steel pipes other than double-turn stainless steel pipes.

[0022]

[Example] SUS with a thickness of 0.35 mm was used as a hoop material.
Both sides of a 304L plate are plated with Ni having a thickness of 0.05 μm, and Cu on the brazing material after brazing is further plated thereon.
Using a stainless steel plate having a thickness of 5 μm and plated with Cu so as to secure a concentration of 75% or more, a double-winding process with a diameter of 4.76 mm and a thickness of 0.7 mm was performed by a multi-winding stainless steel pipe manufacturing apparatus shown in FIG. Thereafter, the tube was heat-treated at 1150 ° C. for 4 seconds by direct energization, and then cooled by a cooling device for 1 minute to obtain a double-wound stainless steel tube as a product. As a result, the Cu concentration in the Cu brazing material after brazing was secured at 89%, and stable brazing strength was obtained.

[0023]

As described above, in the multiple-wound stainless steel pipe according to the present invention, the Cu concentration in the brazing material after brazing is reduced to a degree that the strength (such as ductility) of the brazing material after commercialization does not decrease (75%). By maintaining the above, the strength between the multiple winding wall layers can be obtained, and it is of high quality with excellent pressure resistance and workability. Further, since the material is a stainless steel plate, there is no need to apply a corrosion-resistant coating to the outer surface of the pipe unlike iron such as SPCC, and a step of deteriorating the environment is not required, which greatly contributes to environmental improvement.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing, on an enlarged scale, a part of a cross-sectional structure of a hoop material of a multi-turn stainless steel pipe according to the present invention.

FIG. 2 is a schematic diagram showing an example of the overall configuration of the multi-turn stainless steel pipe manufacturing apparatus according to the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hoop material 1-1 Stainless steel plate 1-2 Ni plating layer 1-3 Cu plating layer 11 Multiple winding forming apparatus 11-1 Guide roll 11-2 Forming roll 11-3 Finishing type roll 11-4 Rod with swimmer 12 Heating Apparatus 13 Press roll 14 Cooling device 15 Double winding tube

Claims (1)

[Claims] 1. A hoop material made of a stainless steel plate having a brazing material applied to its surface is plastically deformed into a tube, and the brazing material between the walls of the multi-winding tube is melted. A multi-turn stainless steel pipe manufactured by cooling, which has a surface coated with Ni plating having a thickness of 0.1 μm or less as a hoop material, and further has a Cu concentration of 75% or more in the brazing material after brazing. A multi-turn stainless steel pipe characterized by using a stainless steel sheet plated with Cu having a thickness of 4 to 8 μm.