JPS591489B2 - Manufacturing method of composite metal pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an advantageous method for manufacturing composite metal tubes, which are used, for example, as brake pipes for motor vehicles.

Well-known metal tubes of this type are produced by metallurgy, in which a composite metal plate consisting of a mild steel plate and a thin copper plating layer is wound overlappingly to form a tube shape, and then heated to cover the overlapped portion using the copper plating layer. Some are obtained by bonding to the body by chemical bonding.

According to this method, there is a limit to the thickness of the copper layer on the surface of the metal tube since it is a plating formation layer, so even if copper of that thickness acts on the bonding of the overlapping parts, it will not have corrosion resistance. The disadvantage is that it is difficult to expect an improvement in performance. Moreover, because the copper layer is thin, when connecting tubes to each other or connecting tubes to other metal parts, it is generally necessary to use silver solder, which is very expensive and has a high melting point, as a solder alloy for connections. , which is also very disadvantageous in this respect.

In other words, it is difficult to use low-temperature brazing materials such as phosphor copper solder, brass solder, and solder. The present invention was made for the purpose of providing a method for manufacturing a composite metal pipe that can ensure and improve corrosion resistance by reliably increasing the thickness of the copper layer, and also allows the use of low-cost metals as the solder alloy for connections. Then, by overlapping thin copper plates on both sides of the steel plate and joining them together by cold pressure welding, a copper-layer steel composite plate with each copper layer having a thickness of 12 to 50μ made of the copper plates was manufactured, and then this A composite metal tube characterized in that a composite plate is rolled and formed into a tube shape, then heated to near the melting point of copper, and the overlapped portion is joined to a body by metallurgical bonding using the copper layer. This relates to the manufacturing method.

The present invention has a remarkable feature in the method of manufacturing a composite metal plate of copper and steel, which is the base material of this kind of composite metal pipe. This was done by finding the effective range of As the steel plate, an iron-based metal plate is generally used which is inexpensive and has excellent bending workability.

Stainless steel sheets have excellent corrosion resistance and mechanical strength, but have drawbacks in workability.

The above-mentioned copper plates include various copper alloy plates including pure copper.

The use of copper and copper alloy plates is extremely simple and reliable in ensuring the thickness of the composite plate according to the above-described manufacturing method, and in this respect, the present invention is extremely unique and advantageous in comparison with the conventional plating method. This is an advantageous method, and at the same time, by appropriately selecting the type of copper alloy plate, it is possible to easily impart various desirable properties such as mechanical strength and corrosion resistance to this type of metal tube.

Copper and copper alloys provide excellent corrosion resistance to metal pipes, and when manufacturing pipes, they are used as fusion metals to join overlapping parts of composite plates by heating in the rolled state. It is an extremely valuable component that serves as a part of the solder joint when connecting pieces or connecting pipes to other parts.

To explain the thickness of copper, Figure 3 shows that when a certain plastic deformation force is applied by bending to a composite metal plate made by integrally coating both sides of a mild steel plate with copper, the thickness of the composite metal plate is The relationship between the thickness of the copper of the plate and the amount of springback is shown by a curve.

Note that the amount of springback was measured in degrees.
In this figure, the overall tendency is that when the thickness of copper is thicker, the amount of springback is smaller due to the influence of the copper metal, and therefore a molded body is better for the composite plate as a whole.

Also, as is clear from this Figure 3, the thickness of the copper is 12
As μ becomes smaller, the influence of copper almost disappears, and the amount of spring tension increases significantly, halving its effect on formability.

The following table shows the thickness of copper and the state of connection when using each solder metal when the composite metal plates of the above structure are connected using the solder metal shown in the table. This shows the relationship between As is clear from this table, the use of phosphor copper solder, brass solder, and solder is determined based on the copper thickness of approximately 12 μm. For copper thicknesses of 12 μm or more, the use of these brazing metals is easily possible from the standpoint of connectivity.

However, this does not negate the use of silver solder. Silver solder can obtain a good connection even to a composite plate with a copper thickness of less than 12 μm, and can be used in a wide range of applications.

Therefore, the lower limit of copper thickness is determined to be 12μ.

On the other hand, in FIGS. 4 and 5, a husband 50 is placed on one side of the mild steel plate.
This is a 100x magnification showing the state in which a composite metal plate consisting of a copper layer of μ and 60μ thickness is bent by winding and heated until the copper layer softens. . In FIG. 4, the 50 micron thick copper layer does not flow downward and sag even when heated and softened.

In contrast, in FIG. 5, the 60 micron thick copper layer is in a heated softened state and flows downward throughout, resulting in significant sagging.

This sagging significantly changes the external shape of the metal tube and also causes the copper, etc. to become thinner on the curved surface on the opposite side, which is a very undesirable phenomenon that is counterproductive to excessive copper thickness. .

Changes in external shape make handling, especially bending, extremely difficult. In addition, in a portion that is thickened due to sag, there is a high possibility that a board will form inside the copper layer in that portion after cooling, and there is a risk that the quality of the material may deteriorate.

The heating and softening of the copper layer as described above is necessary when manufacturing this type of metal tube in order to join and integrate the overlapped parts of the composite plates formed into a tubular shape by winding. Therefore, based on the above, the upper limit of the thickness of this copper layer is determined to be 50μ.

From the above explanation, the effective range of the thickness of the copper layer is determined to be 12 to 50 microns.Next, an embodiment of the method for manufacturing a composite metal tube of the present invention will be described with reference to the accompanying drawings.

The composite metal plate 1 shown in FIG. 1 is produced by overlapping copper plates 3, 3 of uniform thickness on both sides of a mild steel plate 2, and bonding them together by passing them between the rolls of a cold welding machine. It was manufactured by forming copper layers 4, 4 with a thickness of 12 to 50 microns on both sides of layer 5. This composite plate 1 is formed into a tubular shape by double winding, heated to near the melting point of copper, and the overlapping portions are joined together by metallurgical bonding using the copper layers 4, 4 as a fusion metal.

Figure 2 shows a composite metal tube in which the overlapping parts of the double-wound composite metal plates are joined together as described above, and has a double wall structure with the steel layer 5 as the base material. be.

According to the manufacturing method of the composite metal tube of the present embodiment carried out in this way, when manufacturing the composite plate 1 which is the matrix of the metal tube, the copper plates 3, 3 are bonded and integrated on both sides of the steel plate 2, respectively. Since the copper layers 4, 4 with a thickness of 12 to 50 μm are formed, the copper layer 4
, 4 can be easily and reliably increased, so that the effectiveness of the copper layer can be maximized when manufacturing metal tubes by heating and connecting metal tubes to each other or connecting metal tubes to other parts. It is possible to utilize these materials to their fullest potential and advance them extremely advantageously, and it is also possible to improve corrosion resistance and extend the service life.

Also, as is clear from the table, when connecting metal pipes together or between metal pipes and other parts, phosphorous copper solder and brass solder, which conventionally could not be used due to the thickness of the copper layer, are used. This makes it possible to use solder joints made of low-cost metals such as solder, which is very economically advantageous. Moreover, since such solder metals can generally be soldered at low temperatures, they exhibit significant advantages in terms of workability.

As explained above, the present invention is a composite metal tube based on a new concept that makes it possible to secure and improve corrosion resistance by reliably increasing the thickness of the copper layer, and also enables the use of low-cost metals as brazing joints. It has provided a method of manufacturing, and its industrial value is extremely great.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of one embodiment of the method for manufacturing a composite metal pipe of the present invention. Figure 1 is a partial sectional view of a composite metal plate, and Figure 2 is a cross-sectional view of a composite metal pipe. . FIG. 3 is a relationship curve between the copper coating thickness of the composite plate and the amount of spring bag, and FIGS. 4 and 5 are diagrams showing the state of the copper coating on the surface of the composite metal tube in a heat-softened state. 1: composite metal plate, 2: mild steel plate, 3: copper plate, 4: copper layer, 5: steel layer.

Claims (1)

[Claims] 1 Thin copper plates are stacked on both sides of a steel plate, and these are joined and integrated by cold pressure welding to produce a copper-covered steel composite plate in which the thickness of each copper layer is 12 to 50μ, and then this composite plate is A method for manufacturing a composite metal tube, which comprises rolling a plate to form a tube, heating it to near the melting point of copper, and joining the overlapped portions together by metallurgical bonding using the copper layer. .