US2138982A - Method for plating metals and alloys - Google Patents

Description

Dec. 6, 1938. u. RAYDT METHQD FOR PLATING METALS AND ALLOYS Filed Dec. 15, 1936 4 Sheets-Sheet 1' Un vznloiv Dec. 6, 1938. u. RAYDT METHOD FOR PLATINC' METALS AND ALLOYS Filed Dec. 15, 193E 4 Sheets-Sheet 2v 172w: nZor:

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gall/Illa 7n zre n Zor Patented Dec. 6, 1938 METHOD FOR PLATING METALS AND ALLOYS.

Ulrich Raydt, Osnabruck, Germany Application December 15, 1936, Serial No. 116,016 In Germany March 28, 1934 Claims.

This invention relates to a method of plating metals and alloys.

The term plating is to be understood in this specification to mean the mechanical application 5 of a layer of one metal or alloy to one or both surfaces of a different metal or alloy, so as to unite the two. h

The work of plating has hitherto presented very great difficulties. Up to the most recent times attempts have been made to find methods of plating metals and alloys which were capable of being used for large scale working but no success in overcoming the material disadvantages of the processes known hitherto was achieved. Thus, plating processes have recently been proposed in which the materials are rolled together at room temperature. These processes suffer from the disadvantage that the connection is essentially of a purely mechanical nature and 20 that a true alloying of the metals takes place only to a very limited extent.

In some cases when it was thought that the employment of welding temperature could not be dispensed with, it has been necessary to sheath the material to be plated with sheet metal, bring it up to the necessary temperature and then roll it out. The use of the sheet metal in this process was for the purpose of preventing injurious oxidation.

These processes have, however, the great disadvantage that it is not possible to roll out band or strips of any desired length, since the size of the billets which are employed is limited. Moreover, the rolling waste which is inevitable with any rolling process is greatly depreciated in value owing to the fact that metals of a different character are combined with one another without it being possible to separate them again mechanically. For instance, in the plating of iron with copper the copper waste is greatly depreciated in value owing to its iron content.

Finally, the known processes also have the disadvantage that only those metals can be combined which can be heated in common to the same temperature. For instance, it is possible to plate iron or steel with copper. The plating of these metals with brass, on the other hand, causes very great difliculty owing to the low melting point of the brass which prevents the basic metal from being heated up to the welding temperature which is most favorable for it,

All these disadvantages are avoided in accordance with theinvention by heating the various metals or alloys and rolling them out together in an atmosphere of a protective gas. In this way bands of any desired length can be plated. The

' bands or strips of the various metals or alloys can be rolled out by themselves before the actual plating. The waste which is then produced is not contaminated by other metals and is; therefore, considerably more valuable than the waste produced with the known processes.

In view of the fact that the most favorable welding temperatures of the metals are above the temperatures at which rapid oxidation occurs in the air, in carrying out the process the plating rolling mill must be provided with a device which allows the material to be kept in a reducing atmosphere, by enveloping the rolls and the material passing through them with this gas, either by. providing suitable passages or by allowing the reducing flame to strike so far out of the heating furnace that it reaches the pass between the rolls.

another.

Previously, it has been possible to plate, for instance, iron and steel with copper Without too much difiiculty, as regards the actual welding,

making use of button plates.

The plating of steel and iron with alloys or metals having considerably lower melting points such as, for example, brass or even aluminum was, however,

The most suitable welding temperature for iron and steel is much too high to allow iron and steel to be heated with brass or even aluminum up to this welding temperature.

In accordance with the invention these disadvantages are overcome by heating the metals to be combined, for example, a strip of iron and a ,strip of brass in different furnaces or muflies up to the respective temperatures which are most suitable for them and then uniting them in the not successful.

plating rolling mill.

In this way excellent alloying is obtained without the quality of the low melting part of the material being unfavorably affected.

The metal or the alloy which is to be brought to the higher temperature can, however, also be a single furnace.

Electric current is conducted simultaneously through the strip of steel so that by the supplementary resistance heating the steel reaches the temperature which is most suitable for it, while the furnace temperature is so adjusted that the brass reaches its most favorable plating temperature. The current can be conducted to the metal in known manner, e. g. over contact rollers, and in some cases the stand or housing of the rolls used for the welding can be employed for the conduction of the current.

In practice the method is carried out in such a way that the strip of steel which is in the middle does not come into contact with the strips of brass which are outside until immediately in front of the rolls. This-condition may be easily fulfilled. If for instance, the current is conducted by way of contact rollers care must be taken that at least one pole is in contact only with the strip of metal to be heated, in the example the strip of steel, and is insulated from the other strips. If the stand or housing of the rolls is used for current conduction the other pole must be insulated.

The strips or bands can be prevented from touching one another prematurely in front of the rolls by stretching the bands suificiently tightly, by guide rollers, separating walls or the like. .If desired, a partof the metals or alloys to be plated together can be brought to the welding temperature solely by means of resistance heat- 8.

In order, when plating strips or hands, to prevent the latter from becoming displaced in relation-to one another in front of the plating rolls and entering obliquely between the rollers, the bands are, in accordance with the invention braked in front of the rolls. In general, it is suflicient if only the bands of the material forming the plating are braked while the band forming the core usually does not require to be braked.

The bands can be braked in front of the rolling mill or even in front of theheating furnace. For braking, ordinary friction brakes, a second rolling mill which can simultaneously effect a cold rolling, oreddy current brakes, the energy of which can be in great part recovered in preheating the band, can be employed. The braking should in each case be adapted to suit the special properties of the material, so that in general bands of different metals or of different alloys are braked with different force.

The invention is of particular importance for the plating of strips or hands. very important advantages also in the plating of slabs or billets.

For carrying out the new plating process a very great variety of apparatus can be employed. Some forms of apparatus which are particularly suitable are illustrated by way of example in the accompanying drawings, in which:

Figure 1 shows in elevation a twin rolling mill with a heating furnace for plating on one side;

Figure 2 shows the same rolling mill and furnace in plan;

Figure 3 is a partial elevation showing the rolls together with cooling device and also the outlet lip of the heating furnace;

Figure 4 shows one of the rolls in plan;

Figure 5 shows the rolls of a three-high mill together with the outlet lip of the heating furnace;

Figure 6 is an elevational view of a twin rolling mill and heating furnace for plating both sides of a strip or band forming the core;

Figure 7 is a section on a larger scale through a band plated on one side;

It has, however,

7 Figure 8 is a sectional view through a band plated on both sides likewise on a larger scale;

Figure 9 is an elevational view of a three-high mill together with the heating furnace and a roller track;

Figure 10 shows the same rolling mill furnace and roller track in plan.

In order that the drawings may not be unnecessarily extended, the furnaces in Figures 1, 2 and 6 are not shown in their full length, only the ends of the furnace being shown, while the central part of the furnace is broken away.

The installation shown in Figure 1 consists of two chief components, the rolling mill I and the heating furnace 2. The heating furnace 2 is movably mounted in such a manner that it can be moved in the-rolling direction either away from the rolling mill or towards it and also transversely to the rolling direction. The longitudinal movability of the furnace enables the furnace to be drawn back from the rolling mill during the heating-up of the walls or on other occasions when plating is not being carried out, so that the rolls are not unnecessarily heated during this time. The transverse movement of the furnace is of importance for the rolling of billets. The furnace is moved to the side in order to allow a return pass to be made.

It is convenient to arrange at the side of the furnace a roller track which receives the billets coming back from the rolling mill when the furnace has, in the meantime, been pushed to the side. This roller track is only shown in the Figures 9 and 10 for the sake of clearness.

In the example illustrated in Figure 1 in which two bands are to be plated together the transverse movement of the furnace would not be necessary.

The furnace 2 can be heated in any desired manner, e. g. electrically'orby gas. It rests upon wheels 3 which run on rails 4. Attached to the furnace 2 is a carriage 5 with wheels 6. This carriage 5 carries the spools I and the bands.9 and III are wound.

The rails 4 are mounted on a travelling platform II which can be displaced by means of wheels l2 on the rails l3 arranged transversely to the direction of rolling.

The band 9 running from the spool I is braked by a brake l4 before it enters the furnace 2. A brake l 5 is used for braking the band Ill. The band I0 runs over guide rollers I6 and H before entering the mouth I 8 of the furnace 2 together with the band 9. Combustible reducing gases are introduced into this mouth l8 through a pipe l9, and the flame 20 from these gases strikes out of the mouth and prevents the penetration of any injurious oxidizing air into the muflle 2| of the furnace 2. The muflle 2| opens into a lip 22 into which combustible reducing gases are introduced through a pipe 23. The flame strikes out of the lip 22 into-the pass between the rolls and envelops the bands 9 and ID on their way from the furnace into the pass between the rolls. thereby preventing any oxidation of the bands which are above their temperature of rapid oxidation.

The rolling mill l (Figures 1, 2 and 3) consists of the rolls 24 and 25 which are mounted in- 8 on which the rolls may be cooled only from the inside, or only from the outside by means of the cooling hoods, or both from the outside and the inside.

For driving the rolling mill an electric motor 32, for example, is provided, the power from which is transmitted to the roll 25 by gearing, shown in broken lines.

The spool 33, on to which the plated band 35 is wound, is driven from the roller 25 by means of a chain 34 or the like, indicated in broken lines. The band 35 is shown in Figure 7 on a larger scale.

For plating slabs or billets, the furnace'2 illustrated in Figure 1 is preferably connected with a three-high rolling mill, the rolls of which are shown in Figure 5. In addition to the rolls 24 and 25 this rolling mill has also an intermediate roll 36 with a cooling hood 31. Cooling liquid is supplied to the roll 36 through the pipe 38. In plating slabs or billets, the material comes out of the lip 22 and passes first between the rolls 24 and 36 after the furnace 2 has been moved to one side.

The furnace shown in Figure 6 in combination with a twin rolling mill is used for heating a core band and two plating bands. The furnace 2 rests upon wheels 3 which run upon rails 4. The core band 9 is wound. upon a spool I. It is braked by a brake l4 and then enters the mouth I8 into which combustible reducing gases, the flame 20 of which strikes out of the mouth, are introduced through a pipe I9. are wound on spools 8 and I08. The spools are braked by band brakes H4. The spools are in air-tight boxes 39, I39 which are directly connected to the muflles |2|. The band In is led around a guide roller 40, the band 0 around guide rollers |4|, I40. The three bands arrive together in the outlet lip 22 and from there pass between the rolls 24 and 25.

For the explanation of the rolling mill reference is made to the corresponding description of Figure 1.

The band produced by means of the device according to Figure 6, plated on both sides, is shown in Figure 8 on a larger scale, in section transverse to the direction of rolling.

The furnace illustrated in Figure 6 is preferably heated in such a way that the temperature in the muflies |2| in which the plating bands are heated diifers from that in the amide 2|. For instance, for the heating of the muflle 2| a larger number of burners can be provided then for the muflles |2|, or thicker heating coils may be provided if the muflies are electrically heated. The bands I0 and H0 can, however, also be heated by the heat of resistance of electric current which may be conducted to them through the rolls 40 and I40, and they can be supplementarily heated in this manner by resistance heating, should these bands have to be brought to a higher temperature than the core band. The core band can also be supplementarily heated if the plating bands are to have a lower temperature than the core band by electric current supplied to it through one of the rolls of the stack, for instance roll 25 which is insulated from the rest of the machine, and through another roll I43, insulated from the, machine frame on which it is mounted, and connected with a suitable source of current I44.

The three-high rolling mill shown in Figures 9 and 10 is constructed in the same manner as that shown in Figure 5. The rolls 24, 25 and 33 are cooled in suitable manner. In plating the material comes out of the lip 22 of the furnace 2 The plating bands l0 and H0 and passes first between the rollers 35 and 25. On the return pass'it is led between the rolls 24 and 36 after the furnace 2 has been moved to one side. During the movement to and from the rolls the material is supported by a roller track consisting of; two parts 4| and 42. These parts are so constructed that they may be used as lifting tables. The ends near the rolls are depending from two armed levers 4'3 and 44. These levers swing around axis 45, 46. Weights 41, 48 are arranged to compensate the weight of the roller track, the rear ends of which rest on journal bearings 49,50.

The part 4| of the roller track is fixed on the side of the furnace 2 which supports the journal bearing 49 and the bearing of the axis 45.

What I claim is:--

1. The method of plating a sheet of one metal with a sheet of another metal having a substantially different welding temperature from the first metal comprising, heating each of the sheets in non-oxidizing atmosphere to above the respective temperatures of rapid oxidation of the metals to substantially the temperatures most favorable for welding of the respective metals, pressing the sheets together while at said welding temperatures, and protecting the sheets against oxidation by maintaining them in non-oxidizing. atmosphere before and during the pressing, whereby the sheets are integrally united by welding without interference of oxidation scale.

2. The method of welding together long sheets of different metals having substantially different welding temperatures comprising passing the sheets through non-oxidizing atmosphere, heating the sheets while in said atmosphere to above the respective rapid oxidation temperatures of the respective metals to substantially the most favorable welding temperatures of the respective metals, passing said sheets at said welding temperatures through a pressure rolling operation to weld the sheets together while maintaining the sheets enveloped in non-oxidizing atmosphere until welded together to avoid interference with the welding by oxidation of the surfaces to be welded.

3. The method of plating a longstrip of one metal with a sheet of another metal having a substantially difierent welding temperature from the first metal comprising heating the strip of one metal to above its temperature of rapid oxidation, to substantially the temperature most suitable for welding of said one metal by passing said strip through a heating zone having an atmosphere that is non-oxidizing with respect to said one metal, heating said sheet of another metal to above its temperature of rapid oxidation to substantially the temperature most suitable for welding said other metal by passing said sheet through a heating zone having an atmosphere that is non-oxidizing with respect to said other metal, passing said strip and sheet together, at the said welding temperatures respectively, through a pressure rolling operation while enveloped in a non-oxidizing atmosphere to press and weld the sheet and strip together integrally without interference by oxidation products.

4. The method of welding together face to face long sheets of diiferent metals having different welding temperatures comprising feeding said sheets through a heating zone having an atmosphere that is non-oxidizing to the metals to heat said sheets above the temperature of rapid oxidation of the metals to a favorable welding temference with the welding by oxidation products,

5. The method of welding together long sheets of different metals having different most favorable welding temperatures comprising passing the sheets through non-oxidizing atmosphere, heating the sheets while in said atmosphere to above the respective temperatures of rapid oxidation of the respective metals to substantially the most favorable welding temperatures of the respective metals, passing said sheets at said welding temperatures through a pressure rolling operation to weld the sheets together, maintaining the sheets enveloped in non-oxidizing atmosphere until welded together to avoid interference with the welding by oxidation of the surfaces to be welded, and maintaining said sheets under longitudinal tension behind the point of the rolling operation by applying braking force to rear portions of the sheets.

I ULRICH RAYDT.

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