JPH0857533A - Clad bar and its manufacture - Google Patents

Abstract

PURPOSE: To provide a clad bar, which has a proper thin diffusion layer in its joined part, and a manufacture thereof. CONSTITUTION: First, descaling is performed on the inner surface of a titan pipe and the outer surface of a copper round bar. Next, the copper round bar is inserted into the titan pipe to form a preform. Next, drawing is performed against the preform with the reduction of area of 10%. Next, the preform that is through with the drawing process is heated at 650 to 850 deg. in a furnace. Then, inclined rolling is performed on the heated preform, and a clad bus bar is manufactured whose thickness of the diffusion layer generated on the joined face is 5μm or less.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clad bus bar having a circular cross section coated with a corrosion resistant metal material.

2. Description of the Related Art Conventionally, titanium (Ti) as a corrosion-resistant coating metal has been used as an electrode rod used in an electrolytic apparatus or the like.
A flat clad bus bar was used, in which the conductive core metal and copper (Cu) were pressure-bonded by a flat roll.
However, it is desirable to use a clad bus bar having a circular cross section as the electrode rod from the viewpoint of the structure of the electrolysis device. Examples of the method for producing a circular cross-section clad bus bar include rolling pressure welding method, explosion pressure welding method, hot isostatic pressing method and hot isostatic pressing (HIP).
The law is known.

[0001]

However, in the rolling pressure welding method described above, when an attempt is made to manufacture a clad bus bar having a circular cross section by using a hole-shaped roll, the side direction is changed with respect to the vertical joining which is rolled by the hole-shaped roll. However, there is a problem in that it is difficult to manufacture a good circular cross-section clad bus bar and the like, and the roundness of the cross section is poor. Further, the explosion pressure welding method, the hot isostatic pressing method and the HIP method have a problem of low production efficiency.

Further, in the HIP method, the temperature rising precedent type HI is used.
Since the bonding is performed in the P treatment pattern, the holding time is 1 hour or more even in the high temperature range, and Ti and Cu are kept under high temperature and high pressure.
Since and are pressed together, there is a problem that the thickness of the diffusion layer formed at the joint between Ti and Cu increases. That is, if the thickness of the diffusion layer is increased, the contact resistance of the clad bus bar having a circular cross section becomes large, which makes it unsuitable as an electrode rod. Further, as the thickness of the diffusion layer increases, the bonding strength of the circular cross-section clad bus bar also decreases.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a circular cross-section clad bar having a diffusion layer having an appropriate thickness at the joint portion and a method for manufacturing the same. Another object of the present invention is to provide a method for manufacturing a circular-section clad bar having high production efficiency.

[0004]

In order to solve the above-mentioned problems of the prior art and achieve the above-mentioned object, the clad bar of the present invention is inserted into a cladding tube and a hollow portion of the cladding tube. On the joint surface between the core material and the cladding tube and the core material
And a diffusion layer having a thickness of 5 μm or less.

Further, the cladding bar of the present invention preferably has an oxide film on the inner surface of the cladding and the outer surface of the core material in which the ratio (t / D0) of the wall thickness (t) to the outer diameter (D0) is 0.02 or more. A descaling step of descaling, an inserting step of inserting the core material into the cladding tube to form a preform, a drawing step of drawing the preform with a surface reduction rate of 10% or more, and the drawing step Preformed 650-85
It is manufactured by a heating step of heating at 0 ° C., and an inclined rolling step of performing an inclined rolling while applying a tension from the front side by a tensioning device with a surface reduction rate of 15% or more to the preform that has undergone the heating step.

Further, in the method for producing a clad bar of the present invention, the oxide film on the inner surface of the cladding tube and the outer surface of the core material having a ratio (t / D0) of the wall thickness (t) to the outer diameter (D0) of 0.02 or more is used. A descaling step of descaling, an inserting step of inserting the core material into the cladding tube to form a preform, a drawing step of drawing the preform with a surface reduction rate of 10% or more, and the drawing step Preformed 650-85
There are a heating step of heating at 0 ° C., and an inclined rolling step of performing inclined rolling while applying tension from the front side by a tension device at a surface reduction rate of 15% or more to the preform that has undergone the heating step.

[0007]

In the method of manufacturing a clad bar according to the present invention, first, a descaling step is performed. In this descaling step, the oxide film on the inner surface of the corrosion-resistant cladding and the outer surface of the core material, which will be the joint surface, is removed. By removing the oxide film on the joint surface and cleaning it in this way, it is possible to suppress peeling of the joint surface during processing in the later hot tilt rolling, and obtain a predetermined joint strength after joining. Becomes Further, in the present invention, it is not necessary to interpose a brazing material or an insert material on the joint surface.

Next, in the inserting step, the core material is inserted into the corrosion resistant coating tube to form a preform.
Next, a drawing process is performed. In this drawing step, the ratio of the wall thickness (t) to the outer diameter (D0) (t / D0) is 0.02 or more, the core material is inserted into the corrosion-resistant cladding tube (the preform), and cold working is performed. The drawing is performed with a surface reduction rate of 10% or more. The drawing process is performed in order to bring the joint surfaces into close contact. When the springback generated in the corrosion-resistant cladding tube during the drawing process becomes larger than a predetermined value, the joint surface washed in the descaling step in the previous step is oxidized in the heating step in the subsequent step, and the final joint strength of the clad bar is increased. Remarkably deteriorates or cannot be joined. Springback is the ratio of wall thickness (t) to outer diameter (D0) of cladding (t / D0)
Becomes larger and the area reduction rate in the drawing process becomes larger, the smaller. According to the experiment of the present invention, the wall thickness outer diameter ratio
When (t / D0) is 0.02 or more and the area reduction rate is 10% or more, the spring back becomes small and a good joined state can be obtained.

Next, a heating step is performed. In this heating step, the preform after the drawing step is
Heated at 650-850 ° C. This heating step is a step for performing hot working in the inclined rolling step which is a post step.
Further, by heating at a temperature of 650 ° C. or higher in this way, a slight diffusion bonding can be caused on the bonding surface. However, it is not possible to obtain sufficient bonding strength only by diffusion bonding, and thermal stress generated in the cooling process causes interface delamination. For this reason, a post-process tilt rolling process is essential. In addition, by causing a slight diffusion bonding as described above, the cladding tube peels from the core material due to stress generated during processing in the post-process tilt rolling process, and is deformed independently, causing the preform to buckle and bond poorly. Can be suppressed. Further, if the thickness of the diffusion layer is excessively large, the characteristics (bonding strength, contact resistance) as the clad bus bar are deteriorated.
Heating at a temperature of ℃ or less prevents the thickness of the diffusion layer generated at the joint from becoming excessively large.

Next, an inclined rolling process is performed. In this inclined rolling step, the preform heated in the heating step is subjected to inclined rolling at a surface reduction rate of 15% or more while applying tension from the front by a tensioning device. As described above, when the hole-rolling is performed, the upper and lower surfaces, which are the pressing surfaces, are well joined, but the side portions are apt to be poorly joined and the roundness of the product after forming is poor. By performing the inclined rolling, the pressure is evenly applied to the clad bar when viewed in the circumferential direction.
It is possible to obtain a clad bar having a good joining evenly and a good roundness. In addition, by performing inclined rolling with a surface reduction rate of 15% or more, it is possible to cause plastic deformation up to the center of the work material (the preform), and the cross section of the circular cross-section clad bar becomes polygonal. It is possible to prevent the corrosion-resistant coated tube from peeling off. Further, by performing the inclined rolling with a surface reduction rate of 15% or more, the ductile diffusion layer is thinly extended and further broken to form a metal bond, which has the effect of significantly increasing the bonding strength.

At this time, the relationships shown in FIGS. 6 (A) and 6 (B) are established between the diffusion layer thickness and the bonding strength and contact resistance. The combination of moderate heating and inclined rolling causes the diffusion layer to be broken, and it is possible to combine low contact resistance that is preferable for energization and high bonding strength that can sufficiently withstand post-processes such as welding when assembling an electrolytic cell. .

Further, it is indispensable to form the product while applying the tension from the front side by the tension device at the time of the tilt rolling in order to suppress the bending of the product. This is because when straightness is corrected by a strainer or the like in the post process of the clad bar, peeling is likely to occur at the joint surface due to the difference in deformation resistance of the boundary between different metals. Therefore, in the inclined rolling process, it is necessary to apply a tension of 10 to 50% of the breaking limit of the product on the roll exit side to ensure the desired straightness. In addition, this tension effectively acts to suppress unstable forming such as polygonal cross section of the work material.

According to the method for producing a clad bar of the present invention described above, a corrosion-resistant cladding, a core material inserted into the hollow portion of the cladding, and 5 μm on the joint surface between the cladding and the core material.
A cladding bar having a diffusion layer with a thickness of m or less is manufactured.

The clad bar of the present invention produced as described above has a low contact resistance and a large joint shear strength because the diffusion layer formed on the joint surface has a thickness of 5 μm or less, and has excellent characteristics. .

[0015]

EXAMPLES A clad bar and a method for manufacturing the same according to an embodiment of the present invention will be described below. The clad bus bar according to the present embodiment is formed by coating a copper round bar as a conductive core material with a titanium pipe as a corrosion resistant coating tube. FIG. 1 is a diagram for explaining a manufacturing process of the clad bus bar according to this embodiment. As shown in FIG. 1, in the clad bus bar manufacturing process according to this embodiment, a descaling process, an inserting process, a drawing process, a heating process, and a tilt rolling process are sequentially performed. Hereinafter, each step will be described in detail.

The de-scaling each of the oxide film of the outer surface of the inner surface and Domaru rod titanium pipe as a descaling step joint surface, to remove the adherent dirt and oxide film. The titanium pipe has a wall thickness outer diameter ratio (t / D0) of the wall thickness (t) to the outer diameter (D0) of 0.02 or more. This descaling is performed, for example, by a chemical method such as pickling or a mechanical method such as sandblasting or a wire brush. In this way, by descaling the titanium pipe and the copper round bar, a thin diffusion layer can be formed in the joint portion in the subsequent heating step, and a predetermined joint strength can be obtained.

Inserting Process As shown in FIG. 2, a copper round bar 3 is inserted inside the titanium pipe 2 after the descaling process (hereinafter, the entire rod in which the copper round bar 3 is inserted inside the titanium pipe 2 is inserted). Is also referred to as a preform)

After the drawing process and the inserting process are completed, as shown in FIG.
Is drawn at a surface reduction rate of 10% or more. Outer wall thickness ratio of titanium pipe 2 as a corrosion resistant cladding (t / D0)
Is 0.02 or more and the reduction of surface area is 10% or more to suppress the springback and suppress the oxidation of the joint surface in the heating step.

Heating Step The preform 4 which has undergone the drawing step is put in a heating furnace and heated at a temperature of 650 to 850 ° C. for 15 to 30 minutes. Thus, by heating at a temperature of 650 ° C. or higher, a thin diffusion layer can be formed at the joint. Also, 8
By heating at a temperature of 50 ° C. or less, the thickness of the diffusion layer formed at the joint does not become excessive and it is possible to prevent the characteristics of the clad busbar from being adversely affected. Also, like this,
By setting the heating time to 15 minutes or more, the preform 4 can be heated in a uniform temperature state. Also, by setting the heating time to 30 minutes or less, it is possible to prevent the thickness of the diffusion layer generated at the joint portion from becoming excessively large and adversely affecting the characteristics of the clad bus bar.

Inclined Rolling Step In the inclined rolling step, the inclined rolling apparatus is used to reduce the diameter of the above-mentioned heated preform 4 to produce a clad bus bar. Hereinafter, a tilt rolling device used in such a tilt rolling process will be described.
FIG. 4 is a diagram for explaining a tilt rolling apparatus used in the tilt rolling step, FIG. 5 (A) is a top view of the tilt rolling apparatus shown in FIG. 4, and FIG. 5 (B) is a tilt rolling shown in FIG. FIG. 5C is a side view of the apparatus, and FIG. 5C is a front view of the inclined rolling apparatus shown in FIG.

As shown in FIG. 5C, the inclined rolling apparatus of this embodiment has three forming rolls 12a, 12b, 12c arranged at intervals of 120 ° around the pass line 11. As shown in FIG. 4, one end of the rotary shafts of the forming rolls 12a, 12b, 12c has roll driving motors 31a, 31c.
It is fixed to the drive shaft of b. Also, the forming roll 12
a, 12b, 12c and the drive motors 31a, 31b are
The roll elevating cylinders 32a and 32b move up and down as a unit to determine the outer diameter of the product.

The forming rolls 12a, 12b, 12c are inclined at an intersection angle α with respect to the pass line 11 as shown in FIG. 5 (B), and at the pass line 11 as shown in FIG. 5 (A). It has a rotation angle of a feed angle β around an orthogonal axis (center axis of the roll lifting cylinder). By the feed angle β, the forming rolls 12a, 12b, 12c
The feed force in the direction of the pass line 11 in accordance with the rotation of is applied to the preform 4 from the forming rolls 12a, 12b, 12c.

At this time, the roll crossing angle α is fixed at about 45 °, and the feed angle β is preferably variable in the range of 0 to 25 °. In addition, the product pulling portion 30 is a forward stop 3 during tilt rolling.
It retreats from the position of 3 toward the position of the reverse stop 34.
A material clipper 29 that holds one end of the clad bus bar 13 is attached to the product pulling portion 30. The product pulling section 30 grips the clad bus bar 13 by the material clipper 29 during tilt rolling and moves backward while applying a predetermined pulling force. In the slant rolling process, this slant rolling device is used to reduce the preform 4 having an outer diameter D1 to a surface reduction ratio of 1
The clad bus bar 13 having an outer diameter D2 is manufactured by rolling at 5% or more.

In this way, the preform 4 has a surface reduction rate of 15%.
By rolling with, the preform 4 can be deformed to the center of plastic deformation, the cross section of the molded preform 4 becomes polygonal, or buckling occurs in the cross section of the preform 4, resulting in unstable molding. You can avoid that.

FIG. 6A is a graph showing the relationship between the diffusion layer thickness occurring at the clad bus bar joint and the shear strength, and FIG. 6B is the graph showing the diffusion layer thickness occurring at the clad bus bar joint and the contact resistance. It is a graph which shows the relationship with. In the clad bus bar 13 obtained by the above-mentioned inclined rolling process, the thickness of the diffusion layer generated at the joint is 5 μm or less. As a result, the bonding strength of the clad bus bar 13 is shown in FIG.
As shown in (A), it is 17 kgf / mm ² or more, and the contact resistance is 2 × 10 ^-5 Ωcm ² or less, as shown in FIG. 6 (B), and it has excellent characteristics as an electrode rod, for example.

According to the method for manufacturing the clad bus bar of this embodiment, it is possible to uniformly apply pressure to the preform 4 in the drawing process and the inclined rolling process.
As a result, a clad busbar having a good circular cross section can be obtained. Further, due to the characteristics of the process, production efficiency can be improved. Furthermore, the heating time in the furnace is 15 to
It can be set to about 30 minutes, and it is possible to prevent the thickness of the diffusion layer generated at the joint from becoming excessively large and adversely affecting the characteristics of the clad busbar. That is, it is possible to prevent the contact resistance of the clad bus bar from becoming excessive and the shear strength from decreasing. As a result, for example, a good clad busbar can be obtained as an electrode rod.

Hereinafter, the embodiments of the present invention will be described based on more specific examples, but the present invention is not limited to the following examples. Example 1 Descaling Step An inner surface of a titanium pipe having an outer diameter (D0) of 42.7 mm and a wall thickness (t) of 2.0 mm and a ratio (t / D0) of 0.047, and 36.0 mm. Having an outer diameter of 36.
The outer surface of a 0 mm copper round bar was pickled to remove the scale.

Inserting Step The copper round bar 3 was inserted into the inside of the titanium pipe 2 after the descaling step (hereinafter, the entire inserted bar is also referred to as a preform). After completion of the drawing process inserting step was drawn to the preform at a reduction of area of 33%. Put the preform after the heating process drawing process into the furnace and
Heated at a temperature of 50 ° C. for 15 minutes. Inclined rolling process The preform that has undergone the heating process was rolled at a surface reduction rate of 36%. As a result, the clad bus bar produced had a shear bond strength of 19.2 kgf / mm ² and a diffusion layer thickness of 2.3 μm. At this time, the intersection angle α is 45 °
And the feed angle β is 6.0 °, and the forming roll 12
The rotation speed of a, 12b, 12c is 100 rpm,
The retracting speed of the tension device was 70 mm / sec. The tension at this time was 1.7 tonf, which was 23% of the product breaking tension.

[0029]Comparative Example 1 In Comparative Example 1, the area reduction rate was 11% in the inclined rolling process.
The same as in Example 1 except that
Dobs bar was manufactured. Hereinafter, Comparative Example 1 will be described in detail.
ItDescaling process Similar to the first embodiment described above, the outer diameter (D
0) and a wall thickness (t) of 2.0 mm, the ratio (t / D
0) is 0.047 and the inner surface of the titanium pipe is 36.
The outer surface of a 36.0 mm copper round bar having an outer diameter of 0 mm
Descaling was performed by pickling.Insertion process Above the inside of the titanium pipe 2 that has completed the descaling process,
The copper round bar 3 was inserted (hereinafter also referred to as preform.
).Drawing process After the insertion process is completed, the preform is reduced in area by 33%.
It was drawn.Heating process Put the preform after the drawing process into the furnace and
Heated at a temperature of 50 ° C. for 15 minutes.Inclined rolling process Roll the preform after the heating process with 11% reduction in area.
It was As a result, the clad bus bar produced has a cross-sectional shape.
The shape was somewhat diversified. Also this clad busbar
Is beyond the tolerance of diameter (± 0.5 mm)
The bonding rate is 87% and the thickness of the diffusion layer is 7.2 μm.
And the shear strength is 11.4 kg / mm ²Met.
At this time, the intersection angle α is 45 ° and the feed angle β is 6.0.
Is the rotation speed of the forming rolls 12a, 12b, 12c.
The degree is 100 rpm, the retracting speed of the tension device is 70 m
It was m / sec. Also, the tension at this time is 1.7 to
nf, which was 23% of the product breaking tension.

Comparative Example 2 In Comparative Example 2, the heating temperature is 900 ° C. in the heating step.
A clad bus bar was manufactured in the same manner as in Example 1 except that the above was adopted. Hereinafter, Comparative Example 2 will be described in detail. Descaling step Similar to the above-described Example 1, the outer diameter (D) of 42.7 mm
0) and a wall thickness (t) of 2.0 mm, the ratio (t / D
0) is 0.047 and the inner surface of the titanium pipe is 36.
The outer surface of a 36.0 mm copper round bar having an outer diameter of 0 mm was descaled by pickling. Inserting Step The copper round bar 3 was inserted inside the titanium pipe 2 after the descaling step (hereinafter, also referred to as a preform). After completion of the drawing process inserting step was drawn to the preform at a reduction of area of 33%. Put the preform after the heating process drawing process into the furnace and
Heated at a temperature of 00 ° C. for 15 minutes. Inclined rolling process The preform that has undergone the heating process was rolled at a surface reduction rate of 36%. As a result, the thickness of the diffusion layer of the manufactured clad bus bar was 19.3 μm, and the shear strength was 10.5 kg.
/ Mm ² . At this time, the intersection angle α is 45 °, the feed angle β is 6.0 °, and the forming rolls 12a, 1
The rotation speeds of 2b and 12c were 100 rpm, and the retracting speed of the tension device was 70 mm / sec. The tension at this time is 1.7 tonf, which is 23
%Met.

Evaluation When the above-mentioned Example 1 is compared with Comparative Example 1 and Comparative Example 2, the thickness of the diffusion layer of the clad bus bar is smaller in Example than in Comparative Example. Therefore, the clad bus bar of the example has a smaller contact resistance and a larger shear strength than the clad bus bar of the comparative example. As a result, according to the clad bus bar of the example,
Higher current efficiency and higher strength can be obtained as compared with the clad bus bar of the comparative example.

[0032]

According to the method for producing a clad bar of the present invention, it is possible to produce a clad bus bar in which the thickness of the diffusion layer at the joint is 5 μm or less. Further, according to the method for manufacturing a clad bar of the present invention, the production efficiency can be increased. Also,
According to the clad bar of the present invention, the diffusion layer has a thickness of 5 μm.
Since it is below, the contact resistance is low and the shear strength is high. Therefore, if the clad bar of the present invention is used as, for example, an electrode rod, excellent characteristics can be exhibited.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a manufacturing process of a clad bus bar according to the present invention.

FIG. 2 is a diagram showing a state where a copper round bar is inserted inside a titanium pipe in a manufacturing process of the clad bus bar shown in FIG.

FIG. 3 is a diagram for explaining a drawing process in the manufacturing process of the clad bus bar shown in FIG.

FIG. 4 is a diagram for explaining a tilt rolling process in a manufacturing process of the clad bus bar shown in FIG. 1.

5 (A) is a top view of the inclined rolling apparatus shown in FIG. 4, FIG. 5 (B) is a side view of the inclined rolling apparatus shown in FIG. 4, and FIG. 5 (C) is an inclined rolling apparatus shown in FIG. It is a front view of an apparatus.

FIG. 6 (A) is a graph showing the relationship between the diffusion layer thickness occurring at the joint portion of the clad bus bar and the shear strength, and FIG. 6 (B) is the diffusion layer thickness occurring at the joint portion of the clad bus bar and the contact strength. It is a graph which shows the relationship with resistance.

[Explanation of symbols]

2 ... Titanium pipe 3 ... Copper round bar 4.22a ... Preform 11, 19 ... Pass line 12a, 12b, 12c, 25a, 25b, 25c ...
・ Roll 13 ・ ・ ・ Clad busbar 29 ・ ・ ・ Material clipper 30 ・ ・ ・ Product tension part α ・ ・ ・ Intersection angle β ・ ・ ・ Feed angle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Kimura 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Mitsubishi Materials Corporation Central Research Laboratory

Claims (3)

[Claims] 1. A clad bar having a cladding tube, a core material inserted into a hollow portion of the cladding tube, and a diffusion layer having a thickness of 5 μm or less on a joint surface between the cladding tube and the core material. 2. The ratio (t / D0) of the wall thickness (t) to the outer diameter (D0) is 0.
02 or more descaling step of descaling the oxide film on the inner surface of the cladding and the outer surface of the core material, an inserting step of inserting the core material into the cladding tube to form a preform, and reducing the preform A drawing process for drawing at a rate of 10% or more, a heating process for heating the drawn preform at 650 to 850 ° C, and a drawing rate of 15% or more for the preform after the heating process. 2. The clad bar according to claim 1, which is manufactured by an inclined rolling step of performing inclined rolling while applying tension from the front side by an apparatus. 3. The ratio (t / D0) of the wall thickness (t) to the outer diameter (D0) is 0.
02 or more descaling step of descaling the oxide film on the inner surface of the cladding and the outer surface of the core material, an inserting step of inserting the core material into the cladding tube to form a preform, and reducing the preform The drawing process for drawing at a rate of 10% or more, the heating process for heating the drawn preform at 650 to 850 ° C, and the reduction of surface area for the preform after the heating process
% Or more, a method for manufacturing a clad bar, comprising a tilt rolling step of performing tilt rolling while applying tension from the front by a tension device.