Manufacturing method of skin for cathode drum

Abstract

The present invention is characterized by a manufacturing method of a skin for a cathode drum, the method comprising: step 1-1 of preparing an outer skin (100) by heating an outer skin member (10) at a predetermined temperature and then rolling and forging the outer skin member to have a gradual decrease in thickness and an increase to a desired diameter, the outer skin member being obtained by cutting a cylindrical titanium pipe to match the width length (ℓ1) of a skin to be manufactured; step 1-2 of preparing an inner skin (200) by heating at a predetermined temperature an inner skin member (20) at a predetermined temperature and then rolling and forging the inner skin member to have a gradual decrease in thickness and an increase to a predetermined diameter, the inner skin member being obtained by cutting a cylindrical copper tube to a predetermined width length (ℓ2); step 1-3 of machining the inner / outer surfaces of the outer skin and the inner skin to be smooth and spray coating a copper coating layer onto the inner surface of the outer skin; and step 1-4 of allowing the coating layer of the outer skin and the inner skin to closely adhere to each other by insertion in a shrink-fitting manner, in which forcible insertion is conducted with the outer skin heated and the inner skin rapidly cooled.

Description

Method for manufacturing skins for cathode drums

[0001] The present invention relates to a method for manufacturing a skin for a cathode drum, and more particularly, to a method for manufacturing a skin for a cathode drum, in which when an outer skin made of a material resistant to electrolyte and an inner skin made of a material having good electrical conductivity are formed into a cylindrical shape, there is no welding part at all, and when the inner skin is fitted and joined to the cylindrical outer skin, the contact surfaces of the outer skin and the inner skin are in good overall contact without any non-contact parts, so that there is no heat generation and the skin has excellent electrical conductivity.

[0002] Conventional cathode drums that have been manufactured and used in the industry for electrolytic production up to now are manufactured by inserting a skin made of a copper material (hereinafter referred to as an "inner skin") into a cylindrical skin made of titanium (hereinafter referred to as an "outer skin") through heat shrink fitting to enable electrical conduction.

[0003] The conventional cylindrical outer skin mentioned here is made by cutting a titanium plate of 2500 mm or less in width produced in a steel mill thick plate process to a desired length, bending it, rolling it into a round shape so that both ends touch each other, welding it, and then heat-treating the structure of the welded area to form a single mass to form a cylindrical outer skin.

[0004] Although there are some differences depending on the rolling equipment capabilities of steel mills around the world, including Korea, the width and length of titanium plates (thick plates) and copper plates that can be produced at these steel mills are approximately 2500 mm. When titanium plates and copper plates with such limited widths are rolled into a cylindrical shape and welded, the diameter can be varied to 1 m, 2 m, 3 m, etc., but the width and length are all within the range of 2500 mm, which is the size produced at the steel mills.

[0005] Therefore, in order to improve productivity, a limitation arises where larger cathode drum skins with a width of 3000 mm or 4000 mm cannot be manufactured.

[0006] In addition, the grain size of the welded area tissue becomes excessive due to the welding heat generated during the process of bending the titanium plate and welding both ends, and this is a problem that has a negative effect on the quality of the electrolytic foil as the tissue of copper foil, nickel foil, etc. is transferred to the electrolytic foil during the production process of the electrolytic foil.

[0007] In addition, it is difficult to perfectly implement the original shape of the outer skin due to welding deformation during the solution treatment process of putting the welded outer skin into a heat treatment furnace and forming the particles into a single mass, and it is difficult to obtain an outer skin of the desired grain size (7.5 to 8.5) with the same quality as the electrolytic film drum due to the difference in the size of the heat treatment furnace and the heat treatment temperature when charged into the heat treatment furnace.

[0008] And, like the conventional cathode drum, the method of inserting the inner skin into the cylindrical outer skin by heat-fitting does not allow the outer surface of the inner skin to be 100% perfectly sealed to the inner surface of the cylindrical outer skin, and some sections are not sealed.

[0009] In this way, the cathode drum, which has non-contact sections between the outer and inner skins, does not provide a stable and perfect supply of electricity to the entire titanium drum when applying electricity to produce electrolytic foil. Instead, poor electricity supply in some non-contact sections is the main cause of variations in the thickness of the electrolytic foil and excessive heat generation.

[0010] In addition, due to the nature of titanium, the TiO2 (titanium dioxide layer) oxide film that is formed on the titanium surface causes a lot of heat generation due to the resistance caused by the oxide film when electricity is passed through even when the inner skin is inserted, and since more electricity must be passed through to send the desired amount of current, there is a problem that the production cost increases significantly due to the additional cost of having to install a cooling device to prevent overheating of the electrolyte, and there is a problem that it is difficult to achieve quality stabilization of the electrolytic foil.

[0011] Meanwhile, in the <Patent Document 1> below, as a prior art in which a cathode drum is manufactured by the above-mentioned shrink-fit method, there is “Cathode drum for electrolytic deposition and its manufacturing method” (hereinafter referred to as “prior art”) of the Korean Patent Gazette No. 10-2260510 (announced on June 3, 2021) as disclosed in the patent document of the prior art document below.

[0012] The above prior art relates to a cathode drum and a manufacturing method thereof, which are manufactured by a heat-fit method in which an outer cylinder made of titanium is forcibly fitted to the outer surface of an inner cylinder having a copper alloy conductive welding layer and a silver plating layer on the circumferential surface thereof. However, since this is manufactured by a heat-fit method in which the inner cylinder and the outer cylinder are not perfectly sealed, there is a problem as mentioned above.

[0013] [Prior Art Literature]

[0014] [Patent Document]

[0015] (Patent Document 1) "Cathode drum for electrolytic deposition and its manufacturing method" of the Republic of Korea Patent Gazette No. 10-2260510 (announced on June 3, 2021)

[0016] The present invention has been developed to solve various problems occurring in the above-mentioned conventional and prior art.

[0017] The purpose of the present invention is to provide a method for manufacturing a skin for a cathode drum, which has no welded portions at all on the outer skin and inner skin formed in a cylindrical shape, and thus does not require a solution heat treatment process for unifying the grain size of the welded portion as in the past, and which can improve the quality of the electrolytic film without worrying about transfer due to the grain portion.

[0018] Another object of the present invention is to provide a method for manufacturing a skin for a cathode drum having a good electrical conductivity so that when the cylindrical outer skin and inner skin are joined to each other, the entire section is perfectly sealed without any non-contact portion, thereby supplying electricity uniformly and stably to the entire cathode drum without generating heat.

[0019] In order to achieve the above purpose, the method for manufacturing a skin for a cathode drum of the present invention is:

[0020] In one embodiment, a 1-1 step of manufacturing a cylindrical outer skin by cutting a cylindrical pipe formed of a material having good electrolyte resistance to a desired width and length (ℓ1) and heating the outer skin member to a predetermined temperature, and repeating the rolling and forging process so that the thickness gradually becomes thinner and the diameter increases to a desired size; a 1-2 step of manufacturing a cylindrical inner skin by cutting a cylindrical pipe formed of a material having good conductivity to a predetermined width and length (ℓ2) and heating the inner skin member to a predetermined temperature, and repeating the rolling and forging process so that the thickness becomes thinner and the diameter increases to a predetermined size; a 1-3 step of smoothly processing the inner / outer surfaces of the outer skin and the inner skin, and thermally coating a film layer of a metal material having good conductivity on the inner / outer surfaces of either or both of the outer skin and the inner skin; It is characterized by including steps 1-4, in which the outer skin is heated, the inner skin is rapidly cooled, and the outer skin is inserted in a heat-seal manner so that the film layer of the outer skin and the inner skin are in close contact with each other.

[0021] In another embodiment, the method is characterized by including: step 2-1, which is the same as step 1-1; step 2-2, which is the same as step 1-2; and step 2-3, which smoothly processes the inner / outer surfaces of the outer skin and the inner skin; and step 2-4, which inserts the inner skin into the inner surface of the outer skin without shrinkage and causes the outer surface of the inner skin to be bonded to the inner surface of the outer skin by an explosion-bonding clad method.

[0022] In another embodiment, the method is characterized by including: step 3-1, which is the same as step 1-1; step 3-2, which is the same as step 1-2; and step 3-3, which smoothly processes the inner / outer surfaces of the outer skin and the inner skin; and step 3-4, which inserts the inner skin into the inner side of the outer skin as it is, and applies heat to the inner skin and the outer skin and presses them, thereby bonding the outer skin and the inner skin to each other through a hot rolling operation.

[0023] Since the skin for the cathode drum of the present invention has no welding portion between the outer skin and the inner skin, there is no concern that grains of the welding portion will be transferred to the electrolytic film as in the past, and thus there is an effect of improving quality.

[0024] In addition, when the inner skin is fitted onto the outer skin and combined, the entire area is in uniform contact without any non-contact portions, so the overall electrical conductivity can be greatly improved, which has a great effect of reducing electricity costs, and since the cathode drum can be made larger due to the enlargement of the skin, there is an effect of improving the productivity of the electrolytic film and reducing the cost.

[0025] Additionally, since there is little heat generated by electrical resistance, it has the effect of extending the quality and life of the electrolytic chemical.

[0026] Figures 1 to 3 are block diagrams of first to third embodiments listing methods for manufacturing a skin for a cathode drum by different processes according to the present invention.

[0027] Figure 4 is a cross-sectional view of a cylindrical outer skin member made into an outer skin by ring mill forging according to the present invention.

[0028] Figure 5 is a cross-sectional view of a state in which a cylindrical inner skin member is made into an inner skin by ring mill forging according to the present invention.

[0029] Figure 6 is a cross-sectional view of the inner skin being fitted and joined to the outer skin of the present invention.

[0030] Figure 7 is a side cross-sectional view of the inner skin being fitted and joined to the outer skin of the present invention.

[0031] [Explanation of symbols]

[0032] 10: External skin absence

[0033] 20: Internal skin absence

[0034] 100: External skin

[0035] 200: Internal skin

[0036] ℓ1, ℓ2: width length

[0037] φ1,φ2: diameter

[0038] The terms and words used in the present invention described below should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0039] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0040] FIGS. 1 to 3 are block diagrams of first to third embodiments listing methods for manufacturing a skin for a cathode drum by different processes according to the present invention, FIG. 4 is a cross-sectional view showing a state in which an outer skin member is made into an outer skin by ring mill forging, and FIG. 5 is a cross-sectional view showing a state in which an inner skin member is made into an inner skin by ring mill forging.

[0041] And Fig. 6 is a cross-sectional view of the outer skin and the inner skin combined, and Fig. 7 is a side cross-sectional view of the outer skin and the inner skin combined.

[0042] Referring to the drawings shown herein, the method for manufacturing a skin for a cathode drum according to the present invention will be described by example as follows.

[0043] < First embodiment >

[0044] (Step 1-1) External skin shaping stage

[0045] This is a step of making an outer skin (100) using an outer skin material (10) cut into a desired width and length from a cylindrical pipe made of a material with good resistance to electrolyte, as in step 1-1 of Fig. 1.

[0046] Here, it is preferable that the cylindrical tube is formed of any one of titanium, titanium alloy, zirconium, and zirconium alloy, which is a material having good resistance to electrolyte.

[0047] And the forming step of the above outer skin (100) can be formed not only in a width of 2500 mm or less that can be produced in the current steel mill's thick plate process, but also in a width of a greater width, and can be formed without any welding parts.

[0048] That is, assuming that the width of the metal plate that can currently be produced in the thick plate process of a steel mill is '2500 mm', the present invention is explained as follows assuming that it is intended to produce an outer skin with a width (ℓ1) of '4000 mm', which is significantly different from this and cannot be produced in the thick plate process of a steel mill.

[0049] By cutting a cylindrical tube formed of any one of the above titanium, titanium alloy, zirconium, and zirconium alloy metals to the above width length (ℓ1) and making an outer skin member (10), and then performing the rolling and forging process below with the cut outer skin member (10), it is possible to make an outer skin (100) with a significantly larger diameter (φ1) while maintaining the width length (ℓ1) of '4000 mm', which cannot be produced with the current equipment of the steel mill.

[0050] That is, as shown in Fig. 4, when an external skin member (10) cut to a width (ℓ1) that cannot currently be manufactured in a steel mill's thick plate process is heated to a predetermined temperature (800°C to 950°C) in a heating furnace and rolled and forged using a ring rolling mill forging machine, the thickness becomes thinner and the diameter gradually becomes larger.

[0051] By repeating this process several times, the outer skin member (10) can be made into a cylindrical large outer skin (100) having a desired diameter (φ1) without any welding parts while maintaining the width (ℓ1) that cannot be produced with the current equipment of the steel mill. The width (ℓ1) can be made to be as large as possible, for example, '4000 mm' or more, if necessary.

[0052] Here, if the heating temperature is below 800°C, the diameter expandability of the external skin member (10) is reduced, and if it exceeds 950°C, the external skin member (10) may stretch too much and its shape may be deformed, so it is preferable to work within the above temperature range.

[0053] And the thickness of the outer skin (100) that is finally completed in the above step 1-1 can be freely adjusted because it is a ring forging method, but it is preferable to set it within the range of a minimum of 8t and a maximum of 15t for the efficiency of electric conduction and protection of the inner skin (200) inside.

[0054] That is, when the thickness of the outer skin (100) is less than 8t, it is difficult to more safely protect the inner skin (200) in case of surface damage, so it is desirable to form it to at least 8t, and it is desirable that the thickness does not exceed 15t to improve the electric conductivity.

[0055] And, if the thickness of the outer skin (100) is formed to be 15t, there is room to perform surface polishing several times until the thickness becomes 8t when the surface of the outer skin (100) is damaged during use of the cathode drum, so that the lifespan of the outer skin (100) can be extended.

[0056] (Step 1-2) Internal skin shaping stage

[0057] This is a step of making an inner skin (200) using an inner skin member (20) cut to a desired width and length from a cylindrical pipe made of a material with good conductivity, as in steps 1-2 of Fig. 1.

[0058] Here, it is preferable that the cylindrical tube is formed of a metal material such as copper or a copper alloy having good conductivity, and the inner skin (200) can be formed with a width of 2500 mm or less, which can be produced in the current steel mill's thick plate process, as well as a width of a longer width.

[0059] That is, assuming that the width of a metal plate that can be produced in the current steel mill's thick plate process is '2500 mm', the present invention is described below assuming that it is intended to produce an inner skin (200) having a width (ℓ2) of '4000 mm', which cannot be produced with the current steel mill's equipment.

[0060] A cylindrical tube formed of copper or a copper alloy is cut to have a width and length (ℓ2) of the above '4000 mm' to make an inner skin member (20), and then the cut inner skin member (20) is heated in a heating furnace to a predetermined temperature (700°C to 800°C), and the process of rolling and forging using a ring rolling mill forging machine is repeated several times so that the thickness gradually becomes thinner and the diameter (φ2) gradually becomes larger to the desired size.

[0061] At this time, if the temperature of the furnace is below 700℃, the diameter expandability of the inner skin member (20) is reduced, and if it exceeds 800℃, the shape of the inner skin member (20) may be deformed or damaged, so it is desirable to work within the above temperature range.

[0062] If the above rolling forging process is repeated, as shown in Fig. 5, the inner skin member (20) becomes thinner and the diameter (φ2) gradually increases to a desired size, and the rolling forging process is performed until the outer diameter becomes such that it can be inserted into the outer skin (100) by shrink fitting.

[0063] Then, a large cylindrical inner skin (200) with a width (ℓ2) that cannot be produced in a steel mill can be produced without any welding parts.

[0064] And, in order to improve the electrical conductivity, it is preferable that the thickness of the inner skin (200) completed in the above steps 1-2 be formed to be the same thickness as or greater than that of the outer skin (100).

[0065] (Steps 1-3) Surface processing and spray coating steps

[0066] The outer skin (100) and inner skin (200) made in the above steps 1-1 and 1-2 are surface-processed to make the inner / outer surfaces smooth before being combined with each other to remove foreign substances.

[0067] A thermal spray coating is performed by changing a powder or wire-shaped thermal spray material into a semi-molten state using a heat source such as electricity / gas through plasma spraying or a similar thermal spraying method on one or both sides of the inner surface of the surface-processed outer skin (100) or the outer surface of the inner skin (200) and then colliding and laminating it at high speed to form a film layer.

[0068] Here, copper, copper alloy, silver, silver alloy, and indium are all metals with good conductivity, so they can be said to be suitable as spray materials for the above spray coating.

[0069] Accordingly, the film layer by the above-mentioned thermal coating is a film layer made of any one of copper, copper alloy, silver, silver alloy, and indium, and any other metal with good conductivity may be used.

[0070] When a film layer is formed on the outer skin (100) by a thermal spray coating, the resistance to electrical conduction caused by the TiO2 oxide film automatically generated on the inner surface of the outer skin (100) is eliminated.

[0071] (Step 1-4) Combination stage of outer and inner skins

[0072] This is a step of forcibly fitting the inner skin (200) into the outer skin (100) by a heat-fitting method. To this end, it is preferable to apply a certain amount of heat to the outer skin (100) so that the diameter (φ1) can slightly increase when the inner skin (200) is inserted.

[0073] At this time, the inner skin (200) can be inserted as is, but if it is rapidly cooled with liquefied gas or the like, a change occurs in which the outer diameter is slightly reduced, so it can be easily heat-sealed to the heated outer skin (100).

[0074] When pressed, the outer skin (100) and the inner skin (200) are integrally bonded by the spray-coated film layer, so that they are firmly bonded as shown in FIGS. 6 and 7.

[0075] That is, the above-mentioned warrior-coated film layer improves the close contact between the outer skin (100) made of any one of titanium, titanium alloy, zirconium, and zirconium alloy and the inner skin (200) made of copper or copper alloy.

[0076] Therefore, the outer skin (100) and the inner skin (200) can be in good surface contact overall without any non-contact portions, which can be said to greatly improve electrical conductivity, and since there are no welding portions on the surface at all, the quality of the electrolytic foil can be improved.

[0077] < Second embodiment >

[0078] (Step 2-1) External skin forming stage

[0079] This is a step of making an outer skin (100) using an outer skin material (10) cut into a desired width and length from a cylindrical pipe made of a material with good resistance to electrolyte, as in step 2-1 of Fig. 2.

[0080] Here, the cylindrical tube is preferably formed of any one of titanium, titanium alloy, zirconium, and zirconium alloy, which are materials having good resistance to electrolyte, and the outer skin (100) can be formed without any welding part, not only in a width of 2500 mm or less that can be produced in the thick plate process of a steel mill, but also in a width of a longer width that cannot be produced.

[0081] That is, the outer skin member (10) cut into a cylindrical tube to a desired width length (ℓ1) is heated to a predetermined temperature (800°C to 950°C), and the rolling and forging process is repeated several times so that the thickness gradually becomes thinner and the diameter (φ1) gradually becomes larger to a desired size, and then cooled to create an outer skin (100) having a predetermined width length (ℓ1). Since this is the same as 'Step 1-1' of the <First Embodiment>, the description of the remaining parts will be omitted.

[0082] (Step 2-2) Inner skin forming stage

[0083] This is a step of making an inner skin (200) using an inner skin member (20) cut to a desired length from a cylindrical pipe made of a material with good conductivity.

[0084] Here, the cylindrical tube is preferably formed of a metal material such as copper or a copper alloy having good conductivity, and the inner skin (200) can be manufactured without any welding parts, not only in a width of 2500 mm or less that can be produced in the current steel mill's thick plate process, but also in a width of longer than that (ℓ2) that is difficult to produce.

[0085] Below, an example will be given of making an inner skin (200) with a width and length (ℓ2) of '4000 mm' that cannot be produced by a thick plate process in a steel mill.

[0086] Since the inner skin member (20) is made by cutting a cylindrical tube made of a material with good conductivity into a width and length (ℓ2) that cannot be produced by the thick plate process of a steel mill, heating the inner skin member (20) to a predetermined temperature (700°C to 800°C) in a heating furnace, and rolling and forging it with a ring rolling mill forging machine so that the thickness gradually becomes thinner and the diameter (φ2) gradually becomes larger to a desired size, the process is repeated several times to make the inner skin (200), so that it can be said to be almost the same as 'Step 1-2' of the above <First Embodiment>.

[0087] The only difference is that while 'Step 1-2' of <Embodiment 1> is to roll and forge until the diameter of the inner skin (200) becomes a size that can be inserted into the outer skin (100) by shrink fitting, 'Step 2-2' here is to roll and forge until the diameter (φ2) of the inner skin (200) becomes a size that can be inserted without shrink fitting.

[0088] Accordingly, a large cylindrical inner skin (200) of '4000 mm' with a width and length (ℓ2) that cannot be produced in a steel mill plate process can be produced without any welding parts, and it is preferable that the thickness of the inner skin (200) be formed to be the same thickness as or greater than that of the outer skin (100) in order to improve the electrical conductivity.

[0089] (Step 2-3) Surface processing stage

[0090] The outer skin (100) and inner skin (200) made in steps 2-1 and 2-2 above are surface-processed to make the inner / outer surfaces in contact with each other smooth before being combined with each other to remove foreign substances.

[0091] That is, in order to ensure good surface contact when joining together in the next step, the outer skin (100) must have its inner surface processed, and the inner skin (200) must have its outer surface processed. If necessary, both the outer surface of the outer skin (100) and the inner surface of the inner skin (200) may be surface processed.

[0092] (Step 2-4) Combination of outer and inner skins

[0093] Since the surface-processed inner skin (200) is formed with a diameter that can be inserted into the outer skin (100) without heat shrinkage, the inner skin (200) can be easily inserted into the outer skin (100) without the need for heating the outer skin (100) and cooling the inner skin (200) as in the above 'step 1-4'.

[0094] When the inner skin (200) is inserted into the outer skin (100) and the outer skin (100) and the inner skin (200) are exposed to each other by the exposure cladding method, a TiO2 film generated on the surface by mutual penetration of tissues is not formed, and perfect contact is achieved without a non-contact part by the tissue-to-tissue bonding, so that no electrical resistance occurs at the contact surface, thereby improving electrical conduction, can be obtained for a cathode drum.

[0095] <Third embodiment>

[0096] (Step 3-1) External skin forming stage

[0097] This is a step of making an outer skin (100) using an outer skin material (10) cut into a desired width and length from a cylindrical pipe made of a material with good resistance to electrolyte, as in step 3-1 of Fig. 3.

[0098] The above cylindrical tube is preferably formed of one of titanium, titanium alloy, zirconium, and zirconium alloy, which are materials having good resistance to electrolytes. Here, the outer skin (100) can be formed without any welding part, not only in a width of 2500 mm or less that can be produced in the current steel mill's thick plate process, but also in a width of a longer width.

[0099] That is, this is a step of heating an outer skin member (10) cut to a desired width length (ℓ1) of a cylindrical tube to a predetermined temperature (800°C to 950°C) and repeating the rolling and forging process several times so that the thickness gradually becomes thinner and the diameter (φ1) gradually becomes larger to the desired size, and then cooling it to create an outer skin (100) having a predetermined width length (ℓ1). Since this is the same as 'Step 1-1' of <First Embodiment>, the description of the remaining parts will be omitted.

[0100] (Step 3-2) Internal skin forming stage

[0101] This is a step of making an inner skin (200) using an inner skin member (20) cut to a desired length from a cylindrical pipe made of a material with good conductivity.

[0102] That is, a cylindrical tube made of a material with good conductivity is cut into a width and length (ℓ2) that cannot be produced by a thick plate process of a steel mill, and an inner skin member (20) is heated to a predetermined temperature (700°C to 800°C) in a heating furnace, and the inner skin member (20) is rolled and forged with a ring rolling mill forging machine so that the thickness gradually becomes thinner and the diameter (φ2) gradually becomes larger to a desired size. This process is repeated several times, and the diameter is rolled and forged into a size that can be inserted as is without being inserted into the outer skin (100) by shrink fitting. This can be said to be the same as 'Step 2-2' of the <Second Embodiment>.

[0103] Here, the cylindrical tube is preferably formed of a metal material such as copper or a copper alloy having good conductivity, and the inner skin (200) can be manufactured without any welding part with a width of 2500 mm or less that can be produced in the current steel mill's thick plate process, as well as with a width of more than that (ℓ2), and the thickness of the inner skin (200) is preferably formed to be the same thickness as or greater than the outer skin (100) in order to improve the electric conductivity.

[0104] (Step 3-3) Surface processing step

[0105] The outer skin (100) and inner skin (200) made in steps 3-1 and 3-2 above are surface-processed to make the inner / outer surfaces in contact with each other smooth before being combined with each other to remove foreign substances.

[0106] At this time, if only the inner surface of the outer skin (100) and only the outer surface of the inner skin (200) are surface-processed, the surface contact between them can be improved when they are combined in the next step. If necessary, both the outer surface of the outer skin (100) and the inner surface of the inner skin (200) can be surface-processed.

[0107] (Step 3-4) Combination of outer and inner skins

[0108] This is a step of obtaining a skin for a cathode drum by inserting the inner skin (200) into the inner skin (100), and performing a hot rolling operation using a ring rolling mill forging machine while simultaneously applying heat to the inner skin (200) and the outer skin (100) so as to press the outer surface of the outer skin (100) and the inner surface of the inner skin (200) together, thereby joining the outer skin (100) and the inner skin (200) to each other.

[0109] When hot rolling is performed on two different materials, an outer skin (100) and an inner skin (200), the TiO2 film formed on the surface of the outer skin (100) is destroyed, and then the adhesiveness is improved overall without a non-contact part due to artificial bonding of the different tissues, so that electricity conduction is perfect, and since electrical resistance is not generated at the contact surface, electricity conduction can be improved.

[0110] As described above, the cathode drum skin according to the present invention has been described with a focus on the outer skin (100) and the inner skin (200) having a width length that is outside the production capacity range of the steel mill, but it can also be applied when manufacturing the outer skin (100) and the inner skin (200) having a width length that is within the production capacity range of the steel mill. In this case, since there is no welding area at all when the outer skin (100) and the inner skin (200) are formed into a cylindrical shape, there is no concern that grains of the welding area will be transferred to the electrolytic foil as in the past.

[0111] And when the outer skin (100) and the inner skin (200) are combined, the entire surface can be evenly contacted without any non-contact parts, so the electric conductivity is greatly improved, and since the factors causing electric resistance are small, there is almost no heat generation, so the life of the electrolyte can be extended.

[0112] Although the invention made by the present inventor has been specifically described according to the above embodiments, it is obvious to a person skilled in the art that the present invention is not limited to the above embodiments and can be modified in various ways without departing from the spirit thereof.

Claims

1. In manufacturing a skin for a cathode drum, Step 1-1 of manufacturing a cylindrical outer skin (100) by cutting a cylindrical pipe made of a material with good resistance to electrolyte to a width and length (ℓ1) of a desired skin and heating the outer skin member (10) to a predetermined temperature and repeating the rolling and forging process so that the thickness gradually becomes thinner and the diameter (φ1) increases to a desired size; Step 1-2 of manufacturing a cylindrical inner skin (200) by cutting a cylindrical pipe made of a material with good conductivity to a predetermined width and length (ℓ2) and repeating the rolling and forging process so that the inner skin member (20) heated to a predetermined temperature becomes thinner and the diameter (φ2) increases to a predetermined size; Step 1-3 of smoothly processing the inner / outer surfaces of the outer skin (100) and the inner skin (200) in contact with each other, and thermally coating a film layer of a metal material with good conductivity on one or both of the inner surface of the outer skin (100) and the outer surface of the inner skin (200); Step 1-4: The outer skin (100) is heated so that the diameter (φ1) can be slightly enlarged, the inner skin (200) is rapidly cooled, and the inner skin (200) is inserted in a heat-shrinking manner so that the film layer of the outer skin (100) and the inner skin (200) are in close contact with each other; A method for manufacturing a skin for a cathode drum, characterized in that it consists of:

2. In manufacturing the skin for the negative drum, Step 2-1 of manufacturing a cylindrical outer skin (100) by cutting a cylindrical pipe made of a material with good resistance to electrolyte to a width and length (ℓ1) of a desired skin and heating the outer skin member (10) to a predetermined temperature and repeating the rolling and forging process so that the thickness gradually becomes thinner and the diameter (φ1) increases to a desired size; Step 2-2 of manufacturing a cylindrical inner skin (200) by cutting a cylindrical pipe made of a material with good conductivity to a predetermined width and length (ℓ2) and heating the inner skin member (20) at a predetermined temperature and repeating the rolling and forging process several times so that the thickness becomes thinner and the diameter (φ2) becomes larger to a predetermined size; Step 2-3 of smoothly processing the inner / outer surfaces of the outer skin (100) and inner skin (200) in contact with each other; Step 2-4 of inserting the inner skin (200) into the inner skin (100) without heat shrinkage, and bonding the outer surface of the inner skin (200) to the inner surface of the outer skin (100) by means of an explosion-bonding clad method; A method for manufacturing a skin for a cathode drum, characterized in that it consists of:

3. In manufacturing the skin for the negative drum, Step 3-1 of manufacturing a cylindrical outer skin (100) by cutting a cylindrical pipe made of a material with good resistance to electrolyte to a width and length (ℓ1) of a desired skin and heating the outer skin member (10) to a predetermined temperature and repeating the rolling and forging process so that the thickness gradually becomes thinner and the diameter (φ1) increases to a desired size; Step 3-2 of manufacturing an inner skin (200) by cutting a cylindrical pipe made of a material with good conductivity to a predetermined width and length (ℓ2) and repeating the rolling and forging process so that the inner skin member (20) heated to a predetermined temperature becomes thinner and the diameter (φ2) increases to a desired size; Step 3-3 of smoothly surface-processing the inner / outer surfaces of the outer skin (100) and inner skin (200) in contact with each other; Step 3-4 of inserting the inner skin (200) into the inner side of the outer skin (100), and applying heat to the inner skin (200) and the outer skin (100) together while pressing the outer surface of the outer skin (100) and the inner surface of the inner skin (200) together through a hot rolling operation so that the outer skin (100) and the inner skin (200) are joined to each other; A method for manufacturing a skin for a cathode drum, characterized in that it consists of:

4. In any one of claims 1 to 3, The cylindrical tube processed with the outer skin (100) is formed of any one of titanium, titanium alloy, zirconium, and zirconium alloy. A method for manufacturing a skin for a cathode drum, characterized in that a cylindrical tube processed with an inner skin (200) is formed of copper or a copper alloy having good conductivity.

5. In claim 1, The film layer by the warrior coating is A method for manufacturing a skin for a cathode drum, characterized in that the film layer is made of any one of copper, copper alloy, silver, silver alloy, and indium.

6. In any one of claims 1 to 3, When heating for rolling forging The heating temperature of the outer skin member (10) is within the range of 800℃ to 950℃. A method for manufacturing a skin for a cathode drum, characterized in that the heating temperature of the inner skin member (20) is within the range of 700°C to 800°C.

7. In any one of claims 1 to 3, Made by the rolling forging process The thickness of the outer skin (100) is formed within a range of a minimum of 8t and a maximum of 15t for efficient protection of the inner skin (200) and improvement of electrical conductivity. A method for manufacturing a skin for a cathode drum, characterized in that the thickness of the inner skin (200) is formed to be the same as or thicker than the thickness of the outer skin (100).

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