Composite Metal Sheet for Metal Card, Manufacturing Method Thereof, and Metal Card Using the Same

Abstract

The present invention relates to a method for manufacturing a composite metal plate for a metal card. The method for manufacturing a composite metal plate for a metal card according to the present invention comprises: a step of cleaning and surface-treating first and second metal plates to form fine irregularities or fine patterns; a step of sequentially laminating a first metal plate, an intermediate polymer layer, and a second metal plate; and a step of joining the laminated results using a multi-stage rolling process that controls temperature and pressure. The multi-stage rolling process comprises two or more of an initial rolling step performed at low temperature and low pressure, an intermediate rolling step performed at medium temperature and medium pressure, and a rolling step performed at high temperature and high pressure in sequence.

Description

Technology Field

[0001] The present invention relates to a composite metal plate for a metal card, a method for manufacturing the same, and a metal card using the same. More specifically, the present invention relates to a composite metal plate for a metal card made of heterogeneous metal plates joined using a multi-stage rolling bonding process and having structural characteristics for preventing bending, a method for manufacturing the same, and a metal card made of the composite metal plate for a metal card. Background Technology

[0002] Credit cards are used for purposes such as identity verification, payment, and credit extension, and their shapes and designs are becoming increasingly elaborate to imbue them with artistic value and function as accessories. Furthermore, along with services, discounts, and point programs, the appearance and design of credit cards serve as important factors in card selection. Accordingly, card manufacturers are striving to satisfy the diverse needs of customers by devising cards that differ significantly not only in appearance and design but also in functionality.

[0003] To meet these demands, metal cards are being proposed in various forms to provide enhanced, high-quality cards by incorporating the characteristic luster, texture, and weight of metal.

[0004] Korean Registered Patent No. 10-2711701 discloses a “wireless IC metal card having a clad metal structure and a method for manufacturing the same,” wherein a first metal layer, a second metal layer, and a third metal layer are joined together to form a clad metal structure. In this way, a metal card composed of multiple metal layers can effectively express aesthetic design by multiplying the materials of each metal layer, and can also improve durability and corrosion resistance while providing the characteristic weight of metal.

[0005] However, as these high-quality metal cards are constructed by bonding different types of metal layers, there are problems such as increased residual stress, deformation of the metal card, or warping of the metal card due to differences in the physical properties of the different metal layers. These phenomena have an adverse effect on products made using composite metal sheets composed of different metal plates.

[0006] In particular, when bending occurs in a metal card, the bending of the magnetic stripe attached to the back of the card can cause errors in the movement of the card information input device during the process of recording card information. As a result, card information cannot be accurately recorded on the magnetic stripe, leading to card defects. Considering the high manufacturing cost of metal cards, such defects in the card manufacturing process pose a problem that further increases production costs.

[0007] As mentioned above, although various effects can be achieved by composing the metal card with different types of metal plates, a problem arises in that the operation of the metal card is hindered due to the bending phenomenon caused by the different types of metal plates. Prior art literature

[0008] Korean Registered Patent No. 10-2711701, Korean Published Patent No. 10-2020-0093385, Korean Registered Patent No. 10-1897187 The problem to be solved

[0009] In order to solve the aforementioned problems, the present invention aims to provide a method for manufacturing a composite metal plate for a metal card having structural characteristics that allow heterogeneous metal plates to be joined without causing bending.

[0010] In addition, another objective of the present invention is to provide a composite metal plate for a metal card that is formed by joining heterogeneous metal plates and has structural characteristics that prevent bending from occurring.

[0011] In addition, another objective of the present invention is to provide a metal card manufactured using the aforementioned composite metal plate for metal cards. means of solving the problem

[0012] A method for manufacturing a composite metal plate for a metal card according to the first aspect of the present invention for achieving the aforementioned technical problem comprises: a step of laminating a first metal plate having a preset first thickness and a second metal plate having a preset second thickness; and a step of joining the laminated first metal plate and the second metal plate using a multi-stage rolling process; thereby being configured to manufacture a composite metal plate for a metal card composed of heterogeneous metal plates.

[0013] In a method for manufacturing a composite metal plate for a metal card according to the aforementioned features, the multi-stage rolling process preferably comprises two or more of an initial rolling stage performed at a first temperature and a first pressure, an intermediate rolling stage performed at a second temperature and a second pressure, and a rolling stage performed at a third temperature and a third pressure in sequence.

[0014] In a method for manufacturing a composite metal plate for a metal card according to the aforementioned features, the first temperature is set to a temperature capable of recrystallizing the surface of the metal plate having the lower recrystallization temperature among the first and second metal plates, the second temperature is set to an intermediate value of the recrystallization temperatures of the first and second metal plates, and the third temperature is a temperature higher than the second temperature and is more preferably set to a temperature lower than the higher recrystallization temperature among the recrystallization temperatures of the first and second metal plates.

[0015] The method for manufacturing a composite metal plate for a metal card according to the above-described features preferably further comprises the step of cleaning the surfaces of the first and second metal plates to remove oxide films and contaminants from the surfaces of the first and second metal plates before joining the first and second metal plates.

[0016] The method for manufacturing a composite metal plate for a metal card according to the aforementioned features is preferably configured to increase the contact area of ​​the interface between the first and second metal plates by further including a step of treating the surfaces of the first and second metal plates before joining the first and second metal plates to form fine irregularities or fine patterns on the surfaces of the first and second metal plates joined together.

[0017] The method for manufacturing a composite metal plate for a metal card according to the above-described features is preferably configured to insert an intermediate polymer layer between the first metal plate and the second metal plate, laminate them, and then bond them to disperse stress in the bonding area.

[0018] A composite metal plate for a metal card according to a second aspect of the present invention for achieving the aforementioned technical problem comprises: a first metal plate having a preset first thickness; and a second metal plate having a preset second thickness and laminated and bonded to one side surface of the first metal plate; wherein the first and second metal plates are bonded through a multi-stage rolling process in which temperature and pressure are sequentially controlled.

[0019] The composite metal plate for a metal card according to the aforementioned features preferably further comprises an intermediate polymer layer disposed between the first metal plate and the second metal plate.

[0020] In a composite metal plate for a metal card according to the aforementioned features, it is preferable that fine irregularities or fine patterns are formed on the surfaces of the first metal plate and the second metal plate that are joined together. Effects of the invention

[0021] The composite metal plate for a metal card according to the present invention having the above-described structure is formed by joining heterogeneous metal plates, and the contact area is increased by improving the interface structure of the metal plates, and the warping phenomenon can be minimized by using a multi-stage rolling joining process through temperature and pressure control.

[0022] In addition, the composite metal sheet for a metal card according to the present invention can form a rigid joint through metallic bonding between metal atoms and interfacial diffusion by using a multi-stage rolling bonding process in which at least two of the following processes are sequentially performed: an initial rolling process at low temperature and low pressure, an intermediate rolling process at medium temperature and medium pressure, and a final rolling process at high temperature and high pressure. The composite metal sheet for a metal card having such a rigid joint can minimize the occurrence of warping of the metal card.

[0023] In addition, the composite metal plate according to the present invention can further enhance structural characteristics for preventing bending and disperse stress at the joint by inserting an intermediate polymer layer between heterogeneous metal plates that are joined.

[0024] In addition, the method for manufacturing a composite metal plate for a metal card according to the present invention uses a multi-stage rolling process, thereby enabling precise control of the thickness of the composite metal plate, and as a result, the specifications for the card thickness can be easily met.

[0025] Meanwhile, by manufacturing a metal card using a composite metal plate for a metal card having structural characteristics that prevent bending according to the present invention, the bending phenomenon can be minimized and the performance of the metal card can be improved.

[0026] In addition, the method for manufacturing a composite metal plate for a metal card according to the present invention and the composite metal plate for a metal card manufactured thereby are composed of a metal plate made of a material capable of providing an excellent appearance and design on the surface, and a metal plate made of a material having excellent weight or conductivity on the inside, thereby enabling the simultaneous realization of appearance, function, and processability. Brief explanation of the drawing

[0027] FIG. 1 is a flowchart sequentially illustrating a method for manufacturing a composite metal plate for a metal card according to a preferred embodiment of the present invention. FIG. 2 is a cross-sectional view of a composite metal plate for a metal card produced by a method for producing a composite metal plate for a metal card according to a preferred embodiment of the present invention. Specific details for implementing the invention

[0028] The composite metal plate for a metal card according to the present invention is formed by joining dissimilar metal plates and is characterized by having various structural properties that prevent warping. Furthermore, the method for manufacturing the composite metal plate for a metal card according to the present invention is characterized by manufacturing the composite metal plate for a metal card having various structural properties that prevent warping by joining dissimilar metal plates using a multi-stage rolling joining process that sequentially controls temperature and pressure. Hereinafter, the method for manufacturing the composite metal plate for a metal card according to a preferred embodiment of the present invention and the composite metal plate for a metal card manufactured by said method will be described in detail with reference to the attached drawings.

[0029] First, a method for manufacturing a composite metal plate for a metal card according to a preferred embodiment of the present invention will be described in detail. FIG. 1 is a flowchart illustrating a method for manufacturing a composite metal plate for a metal card according to a preferred embodiment of the present invention.

[0030] Referring to FIG. 1, a method for manufacturing a composite metal plate for a metal card according to the present invention first prepares a first metal plate having a preset first thickness and a second metal plate having a preset second thickness (step 100).

[0031] The surfaces of the prepared first metal plate and second metal plate are cleaned to remove oxide films and contaminants from the surfaces of the first and second metal plates (Step 110). The surface cleaning process may be performed differently depending on the material of the metal plate. The surface cleaning process may involve removing oxide scale with an acidic solution such as sulfuric acid or hydrochloric acid, removing oil stains and organic matter with an alkaline aqueous solution, or mechanically removing surface foreign matter using brushing, sandblasting, abrasive rolls, etc. After the cleaning process, any remaining solution on the metal plate must be thoroughly removed and the plate completely dried.

[0032] By removing oxide films and contaminants through the aforementioned surface cleaning process, the first and second metal plates can be bonded uniformly and firmly, and as a result, the bonding quality and the durability of the metal card can be further improved.

[0033] The first metal plate may be composed of aluminum alloy or titanium, and the second metal plate may be composed of stainless steel or copper. Additionally, the first metal plate may be composed of stainless steel and the second metal plate may be composed of copper. The materials of the first and second metal plates may be appropriately combined and set according to the characteristics of the metal card to be manufactured.

[0034] Next, the surfaces of the first and second metal plates are treated to form a micro pattern or micro irregularities on the surfaces of the first and second metals that are joined together (step 120). By this process, the contact area of ​​the interface between the first and second metal plates can be increased by forming a micro pattern or micro irregularities on the surfaces where the first and second metal plates come into contact with each other. Surface treatment processes capable of increasing the contact area may include forming micro irregularities by spraying metal particles such as shot blasting or sand blasting, roughening the contact surface through surface processing such as grinding or brushing, forming micro irregularities through chemical treatment or electrolytic treatment, or processing a micro pattern on the surface through laser texturing or plasma treatment.

[0035] Through the surface treatment process described above, as the contact area of ​​the interface between the first and second metal plates increases, the stress can be distributed more uniformly. Generally, when the contact area of ​​the interface is narrow, local stress concentration occurs as the force is concentrated in the narrow contact area. However, when the contact area of ​​the interface is wide, the stress per unit area is reduced as the same force is distributed over a wide area. As a result, the force is transmitted uniformly across the entire bonding interface, and bending or local deformation can be reduced.

[0036] In addition, when the number of fine irregularities increases at the interface between the first and second metal plates, the metal plates in contact with each other are physically caught and fixed by the fine irregularities, thereby creating a mechanical interlocking effect. In this way, when the interface between the first and second metal plates is mechanically interlocked, the phenomenon of specific parts slipping or lifting can be suppressed even when an external load is applied. As a result, the overall structure of the interface between the first and second metal plates becomes stable, and the possibility of bending can be reduced.

[0037] In addition, if the contact area of ​​the interface between the first and second metal plates is increased, the area where atomic diffusion or interfacial diffusion can occur can also be increased. As a result, the diffusion layer can be formed broadly and uniformly, and the bonding strength of the bonding surface can be increased. Consequently, even if the joint between the first and second metal plates is pulled to one side, the entire structure can withstand it together, thereby reducing the occurrence of bending.

[0038] As described above, by forming a fine pattern or fine irregularities on the surfaces of the first and second metals joined together through a surface treatment process, the contact area of ​​the first and second metal plates can be increased, and as a result, the bending phenomenon occurring in the composite metal plate made of heterogeneous metal plates can be minimized.

[0039] The first and second metal plates, having completed the surface cleaning and surface treatment processes through the aforementioned processes, are laminated together (step 130). At this time, an intermediate polymer layer may be inserted between the first metal plate and the second metal plate during lamination. The inserted intermediate polymer layer may be made of a synthetic resin material such as polyethylene (PE), polypropylene (PP), polyimide (PI), or polyvinyl chloride (PVC). In this way, by inserting and bonding the intermediate polymer layer between the first and second metal plates, stress can be further dispersed and shock absorbed. As a result, the structural stability and durability of the metal card can be further improved.

[0040] With respect to the stacked products, a multi-stage rolling process is performed while sequentially controlling the temperature and pressure (step 140) to join the stacked first metal plate and the second metal plate. The rolling process is a processing method in which metal plates are passed between two or more rotating cylindrical rolls to reduce the overall thickness and obtain the desired shape and mechanical properties. At this time, the cylindrical rolls rotate in opposite directions to draw in the metal plates, compressing and deforming them into thinner forms. During the rolling process, the metal plates undergo plastic deformation to acquire the desired thickness, width, and length.

[0041] The multi-stage rolling process may sequentially perform an initial rolling process, an intermediate rolling process, and a final rolling process, or sequentially perform at least two of these rolling processes, while varying the temperature and pressure according to the material of the metal plates constituting the composite metal plate, the thickness of the metal plates, and the purpose of bonding. The pressure of the multi-stage rolling process can be determined by the thickness of the materials of the metal plates constituting the composite metal plate and the purpose of bonding, and is generally in the range of tens to hundreds of MPa. In industrial processes, interfacial adhesion and diffusion are induced by applying a rolling rate (i.e., thickness reduction rate) of 30 to 70%.

[0042] The rolling bonding temperature of the multi-stage rolling process can be determined by the recrystallization temperature according to the materials of the metal plates constituting the composite metal plate. Below, a multi-stage rolling process is described by example in the case where the first metal plate and the second metal plate are composed of aluminum and stainless steel (SUS), respectively. The recrystallization temperature of aluminum, which is the first metal plate, is approximately 200 to 300°C, and the recrystallization temperature of stainless steel (SUS) is approximately 900 to 1100°C. Therefore, considering the physical properties of the two metal plates, the rolling bonding process can generally be performed in the range of 300 to 600°C. The temperature range for the multi-stage rolling process can be set to a low temperature range, a medium temperature range, and a high temperature range.

[0043] The low temperature range is a temperature range in which the metal plate with the lower recrystallization temperature among the first and second metal plates can recrystallize. In this embodiment, the low temperature range is a temperature of approximately 300°C, which is the temperature at which aluminum can recrystallize. In the low temperature range, plastic deformation of aluminum becomes easier, making it suitable as an initial bonding condition. The medium temperature range can be set as an intermediate temperature between the recrystallization temperatures of the first and second metal plates. In this embodiment, the medium temperature range can be set to a temperature of approximately 400 to 500°C. In the medium temperature range, interfacial diffusion between the first and second metal plates becomes active, thereby improving bonding strength. The high temperature range can be set to a temperature lower than the recrystallization temperature of the metal plate with the higher recrystallization temperature among the first and second metal plates, and higher than the medium temperature range. In this embodiment, the high temperature range is a temperature of approximately 600°C, which is lower than the recrystallization temperature of stainless steel. Bonding can be achieved effectively in high temperature ranges. However, since there is a risk of oxide film formation or interfacial embrittlement in these high-temperature ranges, process optimization is required.

[0044] The method for manufacturing a composite metal plate for a metal card according to the present invention allows heterogeneous first and second metal plates to be joined using plastic processing and interatomic diffusion through a rolling process without the use of adhesives, etc.

[0045] As described above, in the method for manufacturing a composite metal plate for a metal card according to the present invention, the effect of dispersing stress on the bonding interface can be achieved by proceeding with a multi-stage rolling process while controlling temperature and pressure. When a large pressure and temperature are applied once to heterogeneous metal plates, large stress may be concentrated at the interface due to the difference in the coefficients of thermal expansion and elastic moduli of each metal. Therefore, the method according to the present invention can reduce bending phenomena by dividing the temperature and pressure into multiple stages and proceeding with rolling, thereby dispersing stress over several stages.

[0046] Furthermore, different types of metal plates differ in their ductility, or deformation ability. For example, aluminum has high ductility, while stainless steel has relatively low ductility and is hard. In this situation, when performing a multi-stage rolling process, the initial rolling process is carried out at a low temperature and low pressure to deform the aluminum first, thereby expanding the contact area with the stainless steel. Subsequently, the pressure and temperature are gradually increased to ensure uniform adhesion of the interface. Therefore, in the method for manufacturing a composite metal plate for a metal card according to the present invention, gradual interface adaptation is made possible by proceeding with the multi-stage rolling process while controlling the temperature and pressure.

[0047] In addition, as the multi-stage rolling process proceeds by gradually increasing the temperature and pressure, atomic diffusion at the interface proceeds uniformly, thereby preventing the formation of locally thick diffusion layers or weak joints. Therefore, in the method for manufacturing a composite metal plate for a metal card according to the present invention, by proceeding with the multi-stage rolling process while controlling the temperature and pressure, diffusion at the bonding interface is uniformly achieved, so that the overall structure of the bonded composite metal plate becomes flat and the occurrence of warping can be prevented.

[0048] The method for manufacturing a composite metal plate for a metal card according to the present invention sets the temperature and pressure of the initial rolling process, the intermediate rolling process, and the final rolling process, taking into account the aforementioned temperature and pressure.

[0049] The initial rolling process can be set to low temperature and low pressure, the temperature can be set to approximately 250–350°C, which is the temperature at which aluminum softens, and the rolling reduction rate can be set to 10–20%. The purpose of the initial rolling process is to partially destroy the surface oxide film, plastically deform the aluminum to induce initial bonding, and prevent the occurrence of excessive stress.

[0050] The intermediate rolling process can be set to medium temperature and medium pressure, the temperature can be set to 400–500°C, and the rolling rate can be set to 20–30%. The intermediate rolling process is intended to activate the joint through interfacial diffusion, increase mechanical interlocking, and improve the strength of the joint. By activating the joint through interfacial diffusion in the intermediate rolling process, the bonding interface between the first and second metal plates can be made into a state where a metallic bond can be formed.

[0051] The final rolling process can be set to high temperature and high pressure, the temperature can be set to 500~600℃, and the rolling reduction rate can be set to 30% or more. It is preferable to set the temperature of the final rolling process to a temperature lower than the recrystallization temperature of stainless steel. The final rolling process is intended to achieve a desired final thickness, as well as to completely bond the interface between the first and second metal plates and homogenize the diffusion layer while minimizing bending and residual stress.

[0052] Hereinafter, with reference to the attached drawings, the structure of a composite metal plate for a metal card produced by the aforementioned manufacturing method will be described in detail.

[0053] FIG. 2 is a cross-sectional view illustrating a composite metal plate for a metal card produced by a method for producing a composite metal plate for a metal card according to a preferred embodiment of the present invention. Referring to FIG. 2, the composite metal plate for a metal card (1) according to the present invention comprises a first metal plate (100) and a second metal plate (110). Meanwhile, the composite metal plate for a metal card (1) according to the present invention may further comprise an intermediate polymer layer (120) between the first and second metal plates.

[0054] The first metal plate (100) is a metal plate having a predetermined first thickness, and the second metal plate (110) is a metal plate having a predetermined second thickness. The first metal plate (100) and the second metal plate (110) can be stacked and arranged together. The first and second metal plates are made of metals of different materials. The first and second metal plates can be joined through a multi-stage rolling process to form a composite metal plate.

[0055] The surfaces where the first metal plate (100) and the second metal plate are joined are provided with fine irregularities or fine patterns formed through surface treatment, thereby increasing the surface area of ​​the joining interface between the first and second metal plates.

[0056] The intermediate polymer layer (120) can be placed between the first and second metal plates and can be made of a synthetic resin material such as polyethylene (PE), polypropylene (PP), polyimide (PI), polyvinyl chloride (PVC), etc. In this way, by further providing an intermediate polymer layer between the first and second metal plates, stress can be further dispersed and shock absorbed, and as a result, the structural stability and durability of the metal card can be further improved.

[0057] A metal card can be manufactured using a composite metal plate for a metal card having the structure described above. A metal card manufactured using a composite metal plate for a metal card having the structure described above can prevent warping even if it is composed of different types of metal plates.

[0058] Although the present invention has been described above with reference to preferred embodiments, this is merely illustrative and does not limit the invention. Those skilled in the art will understand that various modifications and applications not exemplified above are possible within the scope of the essential characteristics of the invention. Furthermore, differences related to such modifications and applications should be interpreted as being included within the scope of the invention as defined in the appended claims. Explanation of the symbols

[0059] 1 : Composite metal sheet for metal cards 100 : 1st metal plate 110: Second metal plate 120: Intermediate polymer layer

Claims

Claim 1 A method for manufacturing a composite metal plate for a metal card made of heterogeneous metal plates, comprising: a step of laminating a first metal plate having a preset first thickness and a second metal plate having a preset second thickness; and a step of joining the laminated first metal plate and the second metal plate using a multi-stage rolling process that sequentially performs two or more rolling steps at different temperatures and pressures; wherein the multi-stage rolling process sequentially comprises two or more of an initial rolling step performed at a first temperature and a first pressure, an intermediate rolling step performed at a second temperature and a second pressure, and a rolling step performed at a third temperature and a third pressure. Claim 2 delete Claim 3 A method for manufacturing a composite metal plate for a metal card according to claim 1, wherein the first temperature is set to a temperature capable of recrystallizing the surface of a metal plate having a lower recrystallization temperature among the first and second metal plates, the second temperature is set to a range including the intermediate value of the recrystallization temperatures of the first and second metal plates, and the third temperature is a temperature higher than the second temperature and is set to a temperature lower than the higher recrystallization temperature among the recrystallization temperatures of the first and second metal plates. Claim 4 A method for manufacturing a composite metal plate for a metal card according to claim 1, wherein the method for manufacturing the composite metal plate further comprises the step of cleaning the surfaces of the first and second metal plates to remove oxide films and contaminants from the surfaces of the first and second metal plates before joining the first and second metal plates. Claim 5 A method for manufacturing a composite metal plate for a metal card according to claim 1, wherein the method further comprises the step of treating the surfaces of the first and second metal plates before joining the first and second metal plates to form fine irregularities or fine patterns on the surfaces of the first and second metal plates joined together, thereby increasing the contact area of ​​the interface between the first and second metal plates. Claim 6 A method for manufacturing a composite metal plate for a metal card according to claim 1, wherein the method for manufacturing the composite metal plate is configured to insert an intermediate polymer layer between the first metal plate and the second metal plate, laminate them, and then bond them to disperse stress in the bonding area. Claim 7 A composite metal plate for a metal card produced by a method for producing a composite metal plate for a metal card according to any one of paragraphs 1, 3 to 6. Claim 8 A composite metal plate for a metal card, comprising: a first metal plate having a preset first thickness; and a second metal plate having a preset second thickness and laminated and bonded to one side surface of the first metal plate; wherein the laminated first metal plate and the second metal plate are bonded through a multi-stage rolling process in which two or more rolling steps are sequentially performed at different temperatures and pressures, and wherein the multi-stage rolling process sequentially comprises two or more of an initial rolling step performed at a first temperature and a first pressure, an intermediate rolling step performed at a second temperature and a second pressure, and a rolling step performed at a third temperature and a third pressure. Claim 9 A composite metal plate for a metal card according to claim 8, further comprising an intermediate polymer layer disposed between the first metal plate and the second metal plate. Claim 10 A composite metal plate for a metal card according to claim 8, characterized in that fine irregularities or fine patterns are formed on the surfaces of the first metal plate and the second metal plate joined together. Claim 11 A metal card manufactured using a composite metal plate for a metal card according to any one of paragraphs 8 to 10.

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