METHOD OF NLZi ₁ NUFACTURING COPPER CLAD ALUMINUM BUSBAR

Technical Field

The present invention relates, in general, to a method of manufacturing a copper clad aluminum busbar and, more particularly, to a method of manufacturing a copper clad aluminum busbar, which is conducted in such a manner as to insert an aluminum bar into a copper pipe, which is prepared by extrusion-drawing of copper rather than by welding of a copper plate, and then draw it, so as to prevent the breakdown of a copper layer caused during the drawing process, thus assuring the reliable post processing operations, such as bending, rolling, punching, cutting, and the like, of the copper clad aluminum busbar having a cross section area of 40mm ² or more, and thus allowing the manufacture of various types of busbars .

Background Art

In general, typical copper busbars have circular, rectangular, and other-shaped cross sections, and are used for distributing switch boards, power distribution boards, and for other purposes as well . In order to manufacture copper busbar products, post processing operations, such as bending, rolling, punching, cutting, and the like, are performed.

However, in case of manufacturing the copper busbars using a known cladding method by welding, it is possible to perform the post processing operation for a wire rod having a

cross section area of less than 40mm ² , but in the case of a copper clad aluminum busbar having a cross section area of more than 40mm ² , a defect in a welded portion, such as a crack of a welded copper layer, occurs in the course of the post processing operations of bending, rolling, punching, and cutting.

In order to manufacture a copper clad aluminum busbar having a cross section area of 40 to 200mm ² , an aluminum bar must be clad with a copper plate having a thickness of 3 to 10mm by welding and must be drawn. However, in the welding of a copper plate having a thickness of 3 to 10mm, expensive welding equipment and an expensive pipe-making machine are required, and a plurality of welding defects occurs in the welded portions, thereby remarkably decreasing productivity.

Disclosure of the Invention

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method of manufacturing a copper clad aluminum busbar, which is conducted in such a manner as to insert an aluminum bar into a copper pipe, which is prepared by extrusion-drawing of copper rather than by welding of a copper plate, and then draw it, so as to prevent the breakdown of a copper layer caused during the drawing process, thus allowing the manufacture of various types of busbars .

In order to accomplish the above object, the present

invention provides a method of manufacturing a copper clad aluminum busbar, comprising: (a) processing an aluminum bar into a rod pre-treating the aluminum bar; (b) inserting the aluminum bar into a copper tube to prepare a composite bar having a predetermined structure, and drawing the composite bar such that the aluminum bar and the copper tube of the composite bar are brought into close contact with each other at an interface thereof; (c) pre-treating the composite bar in order to prevent a lubricant or machining oil from infiltrating between the aluminum layer and the copper layer of the composite bar; (d) processing a leading end of the composite bar at a predetermined angle, making the copper layer longer than the aluminum layer by a predetermined length, and then ejecting the copper layer using the ejecting unit; (e) drawing the ejected composite bar using the heat drawing unit such that the aluminum layer and the copper layer of the composite bar are brought into tight contact with each other at the interface thereof; and (f) processing the heated and drawn composite bar into a busbar form by rolling the composite bar and then drawing the rolled composite bar using the second drawing unit configured to produce a busbar having a desired shape.

According to the present invention, equipment for welding a copper plate and a pipe-making machine are not required because the aluminum bar is inserted into an extruded and drawn copper pipe and is then drawn without welding the copper plate, and even in the case of a copper clad aluminum busbar having a cross section area of 40 mm ² , the copper layer can be prevented from being cracked in the course of the post processing

operations such as bending, rolling, punching, and cutting.

Brief Description of the Drawings

Fig. 1 is a block diagram illustrating an apparatus for manufacturing a copper clad aluminum busbar according to the present invention.

Fig. 2 is a flowchart illustrating a method of manufacturing a copper clad aluminum busbar according to the present invention.

Fig. 3 is a sectional view illustrating one example of a copper clad aluminum busbar having a multilayer concentric circle structure according to the present invention.

Fig. 4 is a sectional view illustrating one example of the shape of a composite bar before ejection using an ejecting unit according to the present invention. Fig. 5 is a sectional view illustrating one example of the shape of a composite bar after ejection using an ejecting unit according to the present invention.

** Description of the elements in the drawings **

110: ALUMINUM BAR PROCESSING UNIT 120: FIRST DRAWING UNIT

130: PRE-PROCESSING UNIT

140: EJECTING UNIT

150: HEAT DRAWING UNIT

160: SECOND DRAWING UNIT

170: SURFACE TREATING UNIT

Best Mode for Carrying Out the Invention

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. First of all, terms and words used in the specification and claims will be explained as meanings and concepts conforming to the spirit of the present invention without departing from the principle that the inventor can pertinently define the concepts of the terms in order to explain the inventor's own invention in the best mode. In case that it is judged that detailed description of the known functions and configuration thereof may obscure the gist of the invention, it should be understood that the detailed description is omitted. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings .

Fig. 1 is a block diagram conceptually illustrating an apparatus 100 for manufacturing a copper clad aluminum busbar according to the present invention. It is preferably understood that all treatment processes are conducted by an aluminum bar processing unit 110 for preparing an aluminum bar A, removing grease from the prepared aluminum bar A and washing the prepared aluminum bar A with alcohol to pulverize an oxide film formed on the aluminum bar A, and ultrasonically washing a surface of the aluminum bar A; a first drawing unit 120 for drawing a composite bar B, which is prepared in a multilayer concentric structure by inserting the aluminum bar A into a

copper tube, such that the aluminum layer and the copper layer are brought into close contact with each other at the interface thereof; a pre-treatment unit 130 for preventing a lubricant or machining oil from infiltrating into the space between the aluminum layer and the copper layer of the composite bar B in plastic processing; an ejecting unit 140 for ejecting the composite bar B having a processed leading end; a heat drawing unit 150 for heating and drawing the composite bar B such that the aluminum layer and the copper layer of the composite bar B are completely brought into close contact with each other; a second drawing unit 160 for processing the heated and drawn composite bar B into a busbar form by rolling the heated and drawn composite bar B, and then drawing the composite bar B using a drawing mold having the busbar form; and a surface treatment unit 170 for treating the surfaces of the aluminum layer and the composite bar B.

As shown in Fig. 1, the apparatus 100 for manufacturing a copper aluminum busbar generally includes the aluminum bar processing unit 110, the first drawing unit 120, the pre- treatment unit 130, the ejecting unit 140, the heat drawing unit 150, the second drawing unit 160, and the surface treatment unit 170.

Hereinafter, a method of manufacturing a copper clad aluminum busbar using the apparatus 100 for manufacturing a copper clad aluminum busbar will be described with reference to Figs. 2 to 5.

[First Process] Processing and pre-treatment of aluminum Bar A

As shown in Fig. 2, after an aluminum bar A is machined into a rod, foreign substances, which adhere to the aluminum bar A during the processing, are removed therefrom, and then an oxide layer formed on the surface of the aluminum bar A is washed (SlO) .

More specifically, oily substances such as rolling oil, wax, and the like, and other foreign substances, which adhere to the aluminum bar A during the processing, are removed from the aluminum bar A (S12) . At this time, the temperature of a sodium hydroxide solution is in the range of 20 to 50°C, and preferably 35°C. The aluminum bar A is immersed in the sodium hydroxide solution and is subjected to an air bubbling treatment (pressure of 1.5 kg/mm ² ) for 5 minutes.

Subsequently, the surface-treated aluminum bar A is washed with an isopropyl alcohol solution having a concentration of 5 to 10% to partially reduce the oxide layer (S14) .

The oxide layer of the aluminum bar A, pulverized through the step S14, is ultrasonically washed (S16) . At this time, the ultrasonic band for washing the oxide layer is in the range of 100 to 500 KHz, and preferably 250 KHz.

[Second Process] Inserting and drawing of copper tube

The aluminum bar A is inserted into a copper tube to form a composite bar B having a multilayer concentric structure

as shown in Fig. 3, and then the aluminum bar A is drawn so that the aluminum bar A and the copper tube of the composite bar B, prepared by inserting the aluminum bar A into the copper tube, can be completely brought into close contact with each other at the interface thereof (S20) .

That is, the composite bar B passes through the first drawing unit 120, thereby reducing the cross section area of the composite bar B and finely pulverizing the oxide layer (Al ₂ O ₃ ) formed on the surface of the composite bar B.

[Third Process] Pre-treatment

Pre-treatment is performed such that a lubricant or machining oil does not infiltrate between the aluminum layer and the copper layer of the composite bar B having a multilayer concentric structure .

That is, copper and aluminum are put in tight contact with each other by plasticizing the composite bar B under a heating and pressurizing state, and an exterior of the composite bar B is sealed with a metal paste in order to prevent the lubricant or the machining oil from infiltrating between the aluminum layer and the copper layer of the composite bar B during the plastic working, such as rolling, extrusion or the like.

[Fourth Process] Ejection

The leading end of the composite bar B is processed at a predetermined angle, the copper layer is formed longer than the aluminum layer by a predetermined length, and the composite bar

B is ejected using the ejecting unit 140 (S4O) .

More specifically, as shown in Fig. 4, the leading end of the composite bar B is processed at an angle of 44 to 60° and preferably 50°, the composite bar B is processed so that the copper layer is longer than the aluminum layer by the predetermined length, and the composite bar B passes through the ejecting unit 140, whereby the composite bar B is processed into the form shown in Fig. 5. This processing is performed to prevent an ejected copper part from being broken when the ejected copper part is pulled in drawing, thereby allowing the composite bar B to pass through the mold of the ejecting unit

140. In the embodiment of the present invention, the predetermined length is in the range of 10 to 20 cm, preferably

15 cm, but the present invention is not limited thereto.

[Fifth Process] Heat drawing

The composite bar B ejected through the fourth process is drawn through the heat drawing unit 150, thereby allowing the interfaces of the aluminum layer and the copper layer of the composite bar B to be placed in tight contact with each other (S50) . For reference, the heat drawing unit 150 employs a general heat pipe principle, and the inner portion thereof is heated to a temperature of 250°C to 600°C and preferably 400°C by a small heat source.

[Sixth Process] Processing and drawing in busbar form The composite bar B heated and drawn through the fifth process is processed into a busbar form through rolling, and is

then drawn by the second drawing unit 160 having the busbar form (S60) .

[Seventh Process] Heat treatment The composite bar B drawn through the sixth process is heat-treated (S70) . In this case, the heat treatment of the composite bar B is conducted in a vacuum state, and the composite bar B is heated to a temperature of 300°C to 450°C and preferably at 380°C.

[Eighth Process] Surface treatment

The surface of the aluminum layer is treated with chemicals in order to prevent it from corroding, and the surface of the composite bar B is entirely or partially electro-plated with silver or tin (S80) .

As described above, although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims .