JPS6219923B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a thin steel strip with or without a copper plating layer on the surface, and the inner surface is coated with a low-melt metal or a base alloy thereof. Regarding the manufacturing method.

In other words, low-melting metals include tin, lead, aluminum, etc., and alloys based on these metals refer to alloys containing 50% or more of tin, lead, or aluminum.
Therefore, metals or alloys selected from the group of these metals or alloys are hereinafter referred to as low melting coating materials or simply coating materials. Note that small-diameter ERW steel pipes are those with a diameter of approximately 20 m/m or less.

Conventionally, the inner surface of ERW steel pipes has been coated with such low-melt coating materials by dipping the pipe into a molten bath of these coating materials after pipe making, but such a method is inefficient and reduces workability. Not only does the film thickness lack uniformity, but excessive use of coating material is unavoidable.

The present invention has improved such drawbacks, and the gist of the present invention will be explained below with reference to an example of a process diagram.

FIG. 1 is an example of a process diagram showing the implementation procedure of the present invention, in which ₀ is the surface roughening process, 1 is the first process, 2 is the second process, and 3 is the third process. The surface roughening process ₀ is provided with a surface roughening device R ₀ and is connected to the first process.

The first step includes a pipe forming roll group R ₁ , a guide roll g, a linear low-melt coating material m, and a gas blowing nozzle n. The nozzle n and the guide roll g are arranged at both side edge parts 1a, 1 in the middle part of the pipe-making roll group _R1 .
Although an example is shown in which it is placed between spaces 2' and 2', the position may be selected as appropriate.

The second step consists of an electrode roll ER, a pressure roll _R2 , and a feed roll group _R3 .

The third process consists of a heating device F, a cooling device C, a group of shaping rolls _R4 , and a product cutting machine s.

The present invention is carried out through each of these steps, and the thin-walled steel strip 1 sent out from the uncoiler U is subjected to roughening treatment on the side surface that will become the inner surface of the tube in a roughening device _R0 . Proceeding to the first step, an open seam tube 2 containing a linear low-melting coating material m is formed, and the open seam tube enters a second step, where the electrode roll ER and pressure roll R ₂ are used to form both side edge portions 1.
a and 1a are glued together in a butt shape to form a sutured tube 3, and then the sutured tube 3 enters a third step with the coating material m inside, and is treated in the heating procedure described later, so that the entire inner surface is coated with the aforementioned coating. The desired electric resistance welded steel pipe 4 is obtained by being covered with a covering material p made of material m. Next, the implementation procedure for each step will be explained.

In the roughening process ₀ , the steel strip that will become the inner surface of the pipe is roughened mechanically or chemically. However, it goes without saying that the roughening device R ₀ can be removed from the illustrated process by winding the steel strip that has been roughened in advance into an uncoiler.

In the first step, the coating material m inserted into the pipe is linear in the illustrated case, and is guided by guide rolls g and continuously supplied onto the rough surface of the trough-shaped concave surface 1b formed during homing. The supply point may be a flat surface before forming a concave surface as long as the surface is roughened. Even when the covering material m is a powder, the supply point is similarly selected appropriately. FIG. 8 shows an example of the procedure for supplying the powder coating material, where H is the hopper of the powder coating material, m is the powder coating material, and other parts are omitted as they are the same as in FIG. 1. When the covering material is a foil, it may be wound around the uncoiler U so that it is positioned in the longitudinal direction of the center portion of the rough surface of the steel strip and is fed out when the steel strip is fed out.

The nozzle n is provided to make the atmosphere inside the pipe heated in the third step described later an atmosphere of non-oxidizing gas or reducing gas, and these gases are blown in the direction of pipe production by this nozzle n. . Further, the nozzle is installed in an inserted manner by appropriately selecting the end portions 1a and 2' between the two side edges of the first step or between the first step and the electrode roller ER.

Open seam tube 2 obtained in the first step above
The cross section of is shown in FIG. 3, where m is the inserted and internal linear covering material, and n' is the insertion part of the nozzle n into the pipe, which is bent in the pipe-making direction. 5 is a copper plating film, indicating that the raw steel strip was copper-plated.

The thus formed open seam tube 2 enters a second step, where both side edge portions 1a on both sides of the gap 2' are formed.
1a is heated by the electrode roll ER and becomes a pressure roll.
It is press-bonded with R ₂ to become the suture tube 3 and enters the third step. A cross section of the suture tube 3 is shown in FIG.
is the adhesive part.

The suture tube 3 formed in the second step enters the heating device F in the third step, and has an atmosphere of the non-oxidizing or reducing gas inside the tube, and outside the tube is nitrogen gas, argon gas, non-oxidizing gas, etc. An atmosphere of gas or atmospheric gas is formed and the coating material m is heated to the melting and flow temperature, and the coating material m contained therein is heated to this temperature and becomes fluidized to coat the entire inside of the tube. This coating effect is due to the spreading effect of the inner surface of the pipe being activated by the atmosphere of the pipe gas, and the low-melting coating material m being melted in a fluid state on the activated inner surface. When melting fluidly on a surface, the wetting area of the inner surface of the pipe differs depending on the type of coating material, so if the wetting area is small and the pipe diameter is large, the spreading effect on the entire inner surface may be lacking. In such cases, it is difficult not only to form a continuous film but also to form a thick film. As mentioned above, the present inventor has previously formed the surface of the strip steel plate to be a rough surface, thereby promoting the melt-spreading effect on the inner surface compared to the case where no roughening treatment is performed.
In addition, it is possible to form a thicker coating,
The reason why such an effect is obtained is that the striations forming the rough surface cause a capillary phenomenon and increase the wetted area on the inner surface of the tube. A cross section of the sutured tube 4 obtained by the method of the present invention is shown in FIG. 5, which shows that a coating p made of a coating material m is formed over the entire inside surface. FIG. 6 is an enlarged partially cutaway cross-sectional view of FIG. 5, which clearly shows the copper plating layer that exists under the coating p. Figure 7 is a diagram corresponding to Figure 6, which shows that the steel strip was coated with copper plating and had a coating P directly on the steel surface, and was obtained by using a strip steel plate that was not copper plated. This indicates that the

According to the method of the present invention, as described above, the wetted area of the inner surface of the pipe of the coating material m is increased, and the formation of a coating on the entire inner surface is promoted, and it is possible to obtain a relatively thick coating. In addition to this, as long as the length of the steel strip continues, the internally coated electric resistance welded pipe can be made into a long length, and it can be easily carried out, so the industrial benefits brought about by the present invention are great.

Specific examples will be given below to compensate for the deficiencies of the present invention.

Example 1 [Strip steel plate 1] Material spcc-1, wall thickness 0.5m/m, width 43.5m/
m, copper plating thickness 4μ [Surface roughening step ₀ ] The surface of the steel plate was rubbed with a width or diagonal width using AA-180 sandpaper.

[First step]: Formation of open seam tube 2 Low melting coating material m Tin wire of φ0.6m/m Feeding speed 20000mm/min for both 1 and m Gas blown from nozzle n H ₂ 10%, Co9%,
CO ₂ 7%, N ₂ balance [Second process]: Formation of suture tube 3 Electrode roll ER voltage 1.7V, current 9000A [Third process]: Formation of suture tube 4 Heat treatment F a, high frequency induction heating output 30KHz, 230KW b, Atmosphere inside the tube Gas blown into the nozzle Atmosphere outside the tube Nitrogen gas c, Heating temperature 710℃ Cooling C Water cooling The sutured tube 4 obtained by cutting it to a length of 5000 m/m through the above steps has an outer diameter of 12.5 m/m, wall thickness 0.5
A tin film P having a film thickness of 5 μm was uniformly formed on the inner surface of a tube consisting of m/m, and was the sutured tube intended by the present invention. Further, as a result of the inspection, a copper plating layer 5 was found under the tin film p.

Example 2 [Strip steel plate 1] Same as Example 1 [Surface roughening step ₀ ] Liquid homing treatment was performed. Injection pressure 3
Kg/cm ² , carborundum 80 meshes [first step] Low-melting coating material m 200 meshes of lead powder Feed rate Same as Example 1 Blown gas from nozzle n Same as Example 1 [Second step] Electrode roll ER Example 1 [Third step] Heat treatment F a. Continuous heating b. Atmosphere inside and outside the tube Same as Example 1 c. Heating temperature 800℃ Cooling c. Water cooling After each of the above steps, cut into lengths of 5000 m/m s The obtained suture tube 4 has an outer diameter of 12.5 m/m and a wall thickness of 0.5 m.
A lead film having a thickness of 8 μm was uniformly formed on the inner surface of a tube consisting of m/m, and was the electric resistance welded tube intended by the present invention. Further, as a result of the inspection, a copper plating layer 5 was found under the lead film p.

Example 3 [Strip steel plate 1] Same as Example 1 [Surface roughening step ₀ ] The steel strip was immersed in a 40% H ₃ PO ₄ aqueous solution. Immersion time 5 minutes, liquid temperature 50℃ [First step] Low melting coating material Aluminum foil Thickness 0.02m/
m, Width 15m/m Feed speed Same as Example 1 Blowing gas from nozzle n Same as Example 1 [Second process] Electrode roll ER Same as Example 1 [Third process] Heat treatment F a, continuous atmosphere heating b, tube Internal and external atmosphere Same as Example 1 c, Heating temperature 950℃ Cooling c Water cooling The suture tube 4 obtained by cutting into a length of 5000 m/m through each of the above steps has an outer diameter of 12.5 and a wall thickness of 0.5 m/m. An aluminum film having a thickness of 2 μm was uniformly formed on the inner surface, and it was the suture tube intended by the present invention.
Also, as a result of the inspection, a copper plating layer 5 was found under the aluminum film p.
was recognized.

Example 4 [Steel strip 1] Same as Example 1 [Roughening process ₀ ] Same as Example 1 [1st process] Low melting coating material m φ0.6 m/m Al88%-Si12% alloy Feed rate Same as Example 1 Nozzle Blown gas from n Same as Example 1 [Second process] Electrode roll ER Same as Example 1 [Third process] Heat treatment Fa a, high frequency induction heating output 30KHz, 230KW b, atmosphere inside and outside the tube Same as Example 1 c, The sutured tube 4 obtained by cutting into lengths of 5000 m/m through each process at a heating temperature of 1050°C or higher has an outer diameter of 12.5 m/m and a wall thickness of 0.5 m/m.
An Al--Si alloy film having a thickness of 3 μm was uniformly formed on the inner surface of the suture tube, which was the suture tube intended by the present invention. Further, as a result of the inspection, a plating layer 5 was found under the aluminum film p.

Example 5 All steps were carried out in the same manner as in Example 1, except that a steel strip without copper plating was used, and similar results were obtained. However, beneath the tin film on the inner surface was a steel skin.

[Brief explanation of the drawing]

The drawings are explanatory diagrams for carrying out the present invention, in which Fig. 1 is a process diagram showing an example of carrying out the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 4 is an enlarged cross-sectional view taken along the line C-C in FIG. 1, FIG. 5 is an enlarged cross-sectional view taken along the line D-D in FIG. 1, and FIG.
The figure is a partially cutaway enlarged view of FIG. 5, FIG. 7 is a view corresponding to FIG. 6 obtained in a different example, and FIG. 8 is a partial process diagram in another example. In addition, ₀ is the roughening process, is the first process, is the second process, is the third process, R ₁ is the tube making roll, ER is the electrode roll, R ₂ is the pressure roll, R ₃ is the support roll, and R ₄ is the Shaping roll, n is a gas blowing nozzle,
m is a low melting coating material, F is a heating device, and C is a cooling device.

Claims (1)

[Claims] 1. A first step of roll-homing the steel strip 1 into the open seam tube 2, and both side edge portions 1 of the steel strip on both sides of the gap 2' of the open seam tube.
a second step of connecting a and 1a with voltage and suturing them;
A third step is to coat the inner surface of the sutured tube thus obtained with a metal or alloy selected from the group of tin, lead, aluminum, or base alloys of these metals (hereinafter these are referred to as low-melting coating materials or simply coating materials). Through the process, a small diameter ERW steel pipe 4 whose inner surface is coated with a low-melting coating material
In manufacturing the steel strip 1, the side that will become the inner surface of the tube is formed into a rough surface, and the rough surface of the steel strip is formed in the first step or at a location before entering the step. Top 1
b, as the roll homing progresses, the low melting coating material m is continuously supplied in the form of a line, foil or powder, and the edges on both sides are A non-oxidizing gas or a reducing gas is blown in the pipe forming direction from between 1a and 1a so that the inside of the pipe to be formed is in an atmosphere of these gases, thus creating an open seam obtained in the first step. The tube 2 is passed through a second step to create a suture tube 3 which contains the covering material m and has the gas atmosphere inside.
Then, in the third step, the suture tube 3 is passed through a heating device F having an atmosphere of nitrogen gas, argon gas, or the above-mentioned gas, thereby melting the existing low-melting coating material m. The inner surface is coated with a low-melting coating material, characterized in that the inner surface of the tube is coated by melting and spreading the coating material m onto the inner surface of the tube by heating it to a temperature near or higher than the flow temperature. A method for manufacturing a small diameter electric resistance welded steel pipe 4. 2. The method for manufacturing a small-diameter electric resistance welded steel pipe according to claim 1, wherein the surface of the steel strip plate to be roughened is a steel surface. 3. The method for manufacturing a small diameter electric resistance welded steel pipe according to claim 1, wherein the surface of the steel strip plate to be roughened is a copper-plated surface. 4. The method for manufacturing a small diameter electric resistance welded steel pipe according to claim 1, 2 or 3, wherein the surface roughening method is a mechanical method. 5. The method for manufacturing a small diameter electric resistance welded steel pipe according to claim 1, 2 or 3, wherein the surface roughening method is a chemical method.