JPH0575481B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a stainless steel clad copper rod in which a cylindrical outer layer material made of stainless steel is fitted onto the circumferential surface of a core material made of copper having a circular cross section. [Prior Art] Due to its structure, stainless steel clad copper rods are used in applications that require both good electrical conductivity and alkali resistance, for example, as cathode feed rods for electrolytic cells containing common salt. This is generally manufactured by explosion bonding or brazing methods. The explosive bonding method uses the energy from exploding gunpowder to bond the outer layer material made of stainless steel and copper to the copper core material inserted inside, while the brazing method uses the energy from exploding gunpowder to bond the outer layer material and the core material. This is a method of joining the two by pouring a noble metal solder such as silver solder between them. [Problems to be solved by the invention] In the case of the former method, the bonding rate and bonding strength between the core material and the outer layer material are both good, but since explosives are used, there is a big problem in terms of ensuring safety. There are problems in that it requires expensive equipment, is unsuitable for mass production, and has high manufacturing costs. In the case of the latter method, the solder is poured between the core material and the outer layer material to join them, so large-scale equipment is not required and manufacturing is possible at low cost. Since it is accompanied by generation, there is a problem that the bonding rate and bonding strength are low. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of manufacturing a stainless steel clad copper rod with high bonding rate and bonding strength with high production efficiency. [Means for Solving the Problems] The present invention descales and degreases and cleanses the outer peripheral surface of the core material and the inner peripheral surface of the outer layer material, respectively, and then removes easily diffused Ni from both materials. The core material is inserted into the outer layer material while being interposed between the two materials, and they are fitted together by cold drawing.The core material, which has a low melting point, is heated to a high temperature within a range that does not melt, and then manufactured. Rolling with high quality. That is, the method for manufacturing a stainless steel clad copper rod according to the present invention is a method for manufacturing a stainless steel clad copper rod in which a cylindrical outer layer material made of stainless steel is fitted onto the circumferential surface of a core material made of copper with a circular cross section. After cutting the circumferential surface of the rod-shaped core material, it is degreased and cleaned, and the inner circumferential surface of the cylindrical outer layer material is pickled, degreased and cleaned, and Ni is added between the core material and the outer layer material. After inserting the core material into the outer layer material with the layers interposed, cold drawing is performed to fit them together, and the fitted material is heated to a temperature of 1030℃ or less to form three or more cone-shaped rolls. It is characterized by rolling with an area reduction rate of 26.5% or more using an inclined rolling mill. [Function] In the present invention, when the fitting material is heated, a diffusion layer is sufficiently formed at the interface between the Ni layer and the core material and the interface between the Ni layer and the outer layer material, and by rolling this, the bonding is achieved. Stainless steel clad copper rods with a circular cross section and high bonding strength are manufactured with high production efficiency. [Example] The present invention will be specifically described below based on the drawings.
FIG. 1 is a front sectional view of the fitting material used in the present invention,
FIG. 2 is a side view thereof, and numeral 10 in the figure indicates a fitting member. The fitting material 10 is a core material 1 made of copper and having a circular cross section.
Ni foil 13 is wrapped around the outer circumference of 1, and a cylindrical outer layer material 12 made of stainless steel is drawn with a drawing machine and fitted onto the outside of the Ni foil 13. After that, it is sent to an inclined rolling mill that is installed downstream of the heating furnace and is capable of high-pressure rolling. FIG. 3 is a schematic diagram showing the inclined rolling mill 4 used in the present invention (in the figure, the rolls 1 and 2 are a sectional view taken along the - line in FIG. 4), and FIG. The front view and FIG. 5 are side views showing the inclination angle β. The inclined rolling mill 4 has three cone-shaped rolls 1, 2, and 3 facing around the pass line.
The rolls 1, 2, and 3 are provided with gorge parts 1a, 2a, and 3a at the exit end of the fitting material 10, and the diameter of the inlet side of the fitting material 10 gradually increases from the gorge part as a border toward the shaft end. The inlet faces 1b, 2b, 3b and outlet faces 1c, 2 are reduced in size and the outlet sides are enlarged to form truncated conical shapes.
c, 3c, and exit surfaces 1c, 2c, 3c.
The distance to the pass line is made to match the distance between the gorge part and the pass line. These cone-shaped rolls 1, 2, and 3 have their entrance surfaces 1b, 2b, and 3b located upstream in the moving direction of the fitting material 10, and the axis Y-Y and the gorge The intersection point O (hereinafter referred to as the roll setting center) with the plane including parts 1a, 2a, and 3a is
They are arranged at approximately equal intervals around the pass line XX on the same plane perpendicular to the pass line XX of the fitting material 10. The axial center line Y-Y of each roll 1, 2, and 3 is centered around the roll setting center, and the front axis end is at the pass line as shown in FIG. They are crossed (inclined) by the intersecting angle γ so as to approach toward It is tilted by an angle β. The rolls 1, 2, and 3 are connected to a drive source (not shown) and are driven to rotate in the same direction as shown by arrows in FIG. 4, and the hot fitting material 10 caught between these rolls is It is rotated around its axis and moved in the axial direction, that is, it is moved in a spiral manner. While the fitting material 10 is being spirally moved between rolls, its outer diameter is reduced at the roll bit part A as shown in FIG. After the rolled surface B of the fitting material 10 is formed into a truncated conical shape, a stainless steel clad copper rod 14 with a circular cross section and a predetermined outer diameter is formed at the gorge portion and the exit surface. Next, a method for manufacturing a stainless steel clad copper rod according to the present invention will be described, in which the above-mentioned fitting material is rolled using such an apparatus. FIG. 6 is a process diagram of the method of the present invention. First, as shown in FIG. 6a, the outer circumferential surface of a copper rod having a circular cross section is mechanically cut to remove scale, and then degreased and cleaned with acetone or the like to create the core material 11. As shown in b, the inner circumferential surface of a cylindrical stainless steel pipe is pickled and then degreased and cleaned in the same manner as before to create an outer layer material 12. For example, a Ni foil 13 having a thickness of about 40 μm is wrapped around the outer peripheral surface of the core material 11 as shown in FIG. 6c, and this is inserted into the outer layer material 12 as shown in FIG. By doing this, a round bar-shaped fitting material 10 shown in FIG. 6e is formed. The reason for wrapping the above Ni foil 13 is that when the core material 11 and the outer layer material 12 are brought into contact and heated and rolled at high temperature, if copper diffuses into the stainless steel, cracks will occur in the stainless steel outer layer material. It is from. Therefore, in the present invention, a diffusion layer is formed between each of the two materials and the Ni foil 13 by interposing Ni, which is easy to diffuse, between the two materials to prevent copper from diffusing into the stainless steel. In this way, both the bonding rate and the bonding strength are improved. In addition, Ni foil 13 is used as core material 1
Instead of wrapping it around 1, wrap it around the inner surface of the outer layer material 12.
Ni plating may also be applied. The fitting material 10 is formed so that there is no gap at the interface between the core material 11 and the Ni foil 13 and at the interface between the outer layer material 12 and the Ni foil 13. In other words, even if the fitting material 10 is heated, oxides are not generated at both interfaces. After that, the fitting material 10 is heated to, for example, 1020°C in a heating furnace.
Heat to. The heating temperature is limited to a temperature lower than 1030 to 1040°C, at which the core material 11, which has the lowest melting point, begins to melt. Stainless steel easily cracks at low temperatures, so when considering the workability of stainless steel, a relatively high temperature of 1030°C or less is preferable. Due to this heating, diffusion layers are formed at both interfaces during rolling, and the bonding rate and bonding strength can be improved. Then, the heated fitting material 10 is rolled using the inclined rolling mill. As a result, the stainless steel clad copper rod 14 having high bonding rate and bonding strength can be manufactured with high production efficiency as shown in FIG. 6f. Next, the reason for using an inclined rolling mill and the reason for limiting the number of cone-shaped rolls will be explained. Generally, as a method of manufacturing round bars in hot heat,
There are hot extrusion methods, hot hole rolling methods, hot forging methods, inclined rolling methods, etc. Now, in order to investigate the characteristics of the various manufacturing methods described above, sample 10 as shown in FIG.
A was created. That is, the outer diameter of the core material 11a is 70 mmφ.
Using an oxygen-free copper rod of
-0.1), and was degreased and cleaned with acetone or the like. On the other hand, the outer layer material 12a is a stainless steel 310S copper rod with an outer diameter of 80 mmφ, and the outer diameter is 77 mmφ (+0.1 to -
0.1), the inner diameter was 67 mmφ (+0.1 to -0), and the inner surface finish accuracy was 0.1), and the inner surface was degreased and cleaned with acetone or the like. Then, the core material 11a wrapped with Ni foil 13a with a thickness of 40 μm on the outside is inserted into the outer layer material 12a, and this is placed in a vacuum chamber to degas to 3×10 ^-4 Torr. The opening at one end of 12a is covered with a circular lid 12b made of the same material and sealed by welding by electron beam welding or the like. When this sample is heated to 1020℃ and then processed by each of the above methods, the outer diameter is reduced to 60℃ in the case of the hot extrusion method.
When the diameter was reduced to mmφ and 40mmφ, the outer layer material 12
A crack occurs in the axial direction. In addition, in the case of hot hole rolling, several passes were performed with an average area reduction rate of 18%, but cracks occurred in the outer layer material 12a during the third pass. Furthermore, in the case of hot forging, the outer diameter was forged to 60 mmφ, but cracks occurred in the outer layer material 12a before it was forged to the target outer diameter. On the other hand, when using an inclined rolling mill, the reduction is continuously applied little by little and high reduction rolling is performed with a final area reduction rate of 80 to 90%. No cracks occur in the outer layer material 12a. For this reason, an inclined rolling mill is used in the present invention.
Further, even when an inclined rolling mill is used, internal cracks caused by so-called Mannesmann fracture occur in the center of the core material 11a when using a two-roll method. In order to prevent this, the present invention uses an inclined rolling mill having three or more rolls. In other words, the reason is that when rolled with two rolls, secondary tension occurs in the center of the material, causing internal cracks, but when rolled with three or more rolls, no secondary tension occurs in the center of the material, causing internal cracks. It depends on not causing [Effect] The bonding strength of the stainless steel clad copper rod manufactured according to the present invention was measured. The materials to be measured were stainless steel pipes (SUS310S) with inner and outer diameters of 66 mmφ and 76.3 mmφ, whose inner and outer surfaces were pickled, degreased and cleaned with acetone, and a copper rod (oxygen-free copper) with finishing accuracy.
After machining the outer diameter to 62 mmφ, degreasing and cleaning with acetone, wrapping a 40 μm thick Ni foil around the outer circumference and inserting it into the stainless steel tube, cold drawing to reduce the outer diameter. After rolling it to 70mmφ and heating it to 1020℃, the outer diameter after rolling was 60mm.
Incline rolling was performed in four ways: φ, 50 mmφ, 40 mmφ, and 35 mmφ. Inclined rolling conditions are roll intersection angle (γ): 5°, roll inclination angle (β): 13°, roll diameter:
180mmφ, roll material: SCM440, roll rotation speed: 100rpm. The measurement method is as shown in Figure 8, where one end of a stainless steel clad copper rod of a predetermined length is set to a constant length h (thickness of the outer layer material x 1.5), and the other end is set to an outer diameter smaller than the outer diameter of the core material. Two test specimens with a diameter of cylindrical part were prepared for each material to be investigated, and one end of the specimen was placed at the edge of a circular opening with a diameter slightly larger than the outer diameter of the core material. In that state, applying a pressing force from the other end side, measure the load P at which the core material and the outer layer material break, and substitute the measured value into the following equation (1) to calculate the shear strength, that is, the bonding strength. I asked for it. Shear strength = P/(π・D・h) ... (1) However, D = outer diameter of core material Table 1 summarizes the results by rolling diameter.

[Table] As a standard value for shear strength, shear strength standard value 10 for copper and copper alloy clad steel specified in JIS G3604
As can be seen from Table 1, when Kgf/mm ² or more was used, a stainless steel clad copper rod with high shear strength, that is, high bonding strength, could be produced according to the present invention. In addition, in order to investigate the properties of the joints of the materials to be measured, scanning electron microscope (SEM) observation, electron probe microanalyzer (EPMA) observation, and ultrasonic flaw detection were performed. As a result, SEM observation revealed that the bonding rate at both interfaces was high, as shown in FIG. 9, and no peeling or presence of oxides was observed. In addition, in the EPMA observation, as shown in Figure 10, the concentrations of the measured elements Ni, Cr, Fe, and Cu change in the thickness direction near both interfaces, which indicates that each element is sufficiently diffused and has good bonding properties. That is understood. Furthermore,
The results of ultrasonic flaw detection showed that there were no defects such as cracks at the interface. As described in detail above, the present invention has no scale adhesion and has a clean surface between the core material and the outer layer material.
A fitting material with a Ni layer is created by cold drawing,
The mating material is heated to a temperature of 1030℃ or less and rolled with an area reduction of 26.5% or more using an inclined rolling mill with three or more cone-shaped rolls, resulting in a stainless steel clad copper rod with a high bonding rate and bonding strength. It has an excellent effect of being able to manufacture with high production efficiency.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of the fitting material used in the present invention, FIG. 2 is a side view thereof, FIG. 3 is a schematic diagram showing an inclined rolling mill 4 used in the present invention, and FIG. 5 is a side view showing the inclination angle β, FIG. 6 is a process diagram of the method of the present invention, FIG. 7 is a sectional view of a test piece for selection of the manufacturing method used in the present invention, and FIG. Figure 8 is an explanatory diagram of the content of the shear strength measurement test, Figure 9 is an SEM observation diagram of the vicinity of the interface of the stainless steel clad copper rod manufactured according to the present invention, and Figure 10 is the
This is the result of EPMA observation. 1, 2, 3... Roll, 4... Inclined rolling mill, 1
0... Fitting material, 11... Core material, 12... Outer layer material,
13...Ni foil, 14...Stereless clad copper rod.

Claims (1)

[Scope of Claims] 1. In a method for manufacturing a stainless steel clad copper rod in which a cylindrical outer layer material made of stainless steel is fitted onto the circumferential surface of a core material made of copper with a circular cross section, the circumferential surface of the rod-shaped core material After cutting, the core material is degreased and cleaned, and the inner peripheral surface of the cylindrical outer layer material is pickled, degreased and cleaned, and the core material is removed with a Ni layer interposed between the core material and the outer layer material. After inserting it inside the outer layer material, cold drawing is performed to fit it, and the fitted material is heated to a temperature of 1030°C or less and then rolled with an inclination rolling machine having three or more cone-shaped rolls with an area reduction rate of 26.5. A method for manufacturing a stainless steel clad copper bar, which comprises rolling at a rolling rate of % or more.