US2386091A

US2386091A - Bimetallic billet and preparation and rolling thereof

Info

Publication number: US2386091A
Application number: US440155A
Authority: US
Inventors: William A Carlson
Original assignee: Superior Steel Corp
Current assignee: Superior Steel Corp
Priority date: 1942-04-23
Filing date: 1942-04-23
Publication date: 1945-10-02
Anticipated expiration: 1962-10-02

Description

Oct. 2, 1945. 2,386,091

BIMETALLIC'BILLET AND PREPARATION AND ROLLING THEREOF W. A. CARLSON Filed April 23. I942 I I INVENTOR VVEZZzamA. Carl-sun dinal extensib'ilities upon rolling of the bimetallic Patented Oct. 2, 1945 UNITED STATES PATENT OFFlCE BIMETALLIC BILLET AND PREPARATION AND'ROLLING THEREOF corporation of Virginia William A. Carlson, Pittsburgh, Pa., assignor to Superior Steel Corporation, Pittsburgh, Pa., a

Application April 23, 1942, Serial No. 440,155

7 Claims. (01. 29-188) making and rolling of bimetallic billets made up of a component of steel and one or more components of relatively soft metal which has a relativelyv great longitudinal extensibility upon rolling of the bimetallic billet.

Consider, for example, the'rolling of a bimetallic billet having a backing member of steel and a facing member or membersof gilding metal. When such a bimetallic billet is heated and hot rolled the gilding metal is extended longitudinally. J during the hot rolling to a greater extent than the steel. If. the steel and gilding metal components are the same length when the billet is formed the gilding metal will roll out to greater length in the hot rolled strip than the steel and thus considerable gilding metal will be wasted. If, on the other hand, the gilding metal is made shorter than the steel when the billet is formed a. portion of the steel is left exposed and during hot rolling the gilding metal is rolled out over such portion. A satisfactory bond between the steel and gilding etal over the originally exposed portion of e. steel is not assured because" of the formatio C of oxide or scale upon such portion of the steel upon heating and hot rolling the billet. The scale may prevent the formation of a satisfactory bond between the gilding metal and th steel with the result that the components may separate in the finished strip when subjected to die forming or other operations.

I have discovered how to avoid undue wastage of gilding metal or whatever relatively soft metal is used s a component of a bimetallic billet with- I out the, disadvantage of the formation .of oxide 5 Y ferred methods of practicing the same proceeds.

or scale upon an originally exposed portion of the steel or other relatively less extensible component. I make a bimetallic billet by forming components of metals having different longitubillet with the component having the greater longitudinal extensibility shorter than that havsemble the components and I provide for protecting against oxidation a portion of the longer component not originally covered by the shorter component so that when the billet is heated and rolled the originally shorter but relatively extensible'component will flow out and cover such protected portion of t e originally longer component,

the two compone' ts in the finished strip being 7 of approximately the same length.

The pr tection of the originally uncovered portion 0 the longer billet'component may be accomplished in various ways. I prefer to cover the;surface portion of such component which is in generally longitudinal alignment with the shorter component so that such surface portion does not substantially oxidize during heating and hot rolling and so that the originally shorter component may flow out over the protected portion of the originally longer component and form a tight bond therewith. I preferably place protecting means over the originally uncovered portion of the l0nger billet component, which protecting means may be displaced by the originally shorter component during rolling. For example, I may employ a slug or small plate of steel or other metal as the protectingmeans or device and fasten it over the portion of the surface of the originally longer billet component which is in generally longitudinal alignment with the originally shorter component When the bimetallic billet is heated and rolled the originally 4/ longer component which was originally covered by the slug or plate so that a satisfactory tight bond in the finished strip between the respective components may be obtained. Preferably the protective device is made of relatively inexpensive metal such as ordinary steel so that its loss in the finished strip is not economically serious.

Other details, objects and advantages of the invention will become apparent as the following description of certain present preferred embodiments of the invention and certain present prec'ertain present preferred embodimentsoi the in I of practicing the same, in which I Figure l is a perspective view of a bimetallic billet with a portion cut away; J I

Figure 2 is a central vertical longitudinal crosssectional perspective view of the billet shown in Figure 1. also with a portion cut away;

Figure 3 is a view similar to Figure 2 showing a modified structure; and

Figure 4 is a view similar to Figures 2 and 3 showing a further modified structure.

Referring now more particularly to the drawing, there is shown in Figures 1 and 2 a bimetallic billet comprising a steel backing member 2 and gilding metal facing members I and 4 assembled with and lying against the backing member at its top and bottom, respectively. The backing member is provided with four projecting flanges I which initially provide with the intermediate surfaces of the backing. member channels in which the facing members 3 are disposed, after which the flanges are peined over against the edges of the facing members to hold the billet components in assembled relationship so that the composite billet may be heated and hot rolled.

As shown, the facing members are preferably relatively thin as compared with the backing member. Each of them is also made materially shorter than the backing member. This is done because the relatively soft material of the facing members has relatively great longitudinal extensibility in rolling of the bimetallic billet, that is, when the billet is heated and hot rolled the facing members roll out to greater length per unit of original length than the backing member. The facing members are preferably made Just enough shorter than the backing member that during rolling the facing members and the backing member will be elongated to approximately the same length, thus avoiding substantial wastage of material. While I am not certain, I believe that the relative longitudinal extensibility between the facing and backing members occurs prior to bonding of such members together and that after they have bonded together due to the pressure applied to them in the rolling mill after they have first been raised to welding heat there will be little if any relative longitudinal extensibility. Experience readily shows how much shorter than the backing member the facing members should be for any given combination of backing and. facing members. I have found that when backing and facing members of approximately the shape and proportions indicated in the drawings are employed the facing members should be ordinari y from two to three inches shorter than the backing member when the length of the billet is of the order of five feet and when the backing member is of ordinary carbon steel and the facing members are of gilding metal (in the neighborhood of 90% copper and in the neighborhood of zinc).

In order to cover and protectthe surface portions of the backing member which lie generally in longitudinal alignment with the facing members but are not originally covered by the facing members I provide slugs or plates 8 as shown which are preferably of the same width as the facing members and which abut the respective facing members end to end as shown in Figure 2 and whose length is such that the total of the length of each facing member and the abutting slug is substantially equal to the length of the backing member. The slugs are preferably made of metal, any relatively cheap metal ordinarily satisfactorily serving the purpose. I prefer to make the slugs of ordinary carbon steel and they may be made of steel identical or substantially identical to that used for making the backing member 2. The thickness of the slugs is not important except that they should be thick enough to serve their purpose and to protect the underlying surface portions of the backing member until the facing members are elongated during rolling to cover such portions. It is convenient to make the slugs of the same thickness as the facing membersand they are thus shown in the drawings.

A above stated, the facing members are applied to the backing member between opposed flanges i whereafter the flanges are peined in against the edges of the facing members to maintain the assembly. I find it desirable to also position the slugs against the backing member and in end to end abutting relationship with the fac ing members at the same time as the facing members are applied and to pein over the flanges against the facing members and the slugs in the same operation. Since the slugs are not intended to form a permanent part of the billet or of the strip to be rolled therefrom it is not essential that they be held as firmly as the facing members, although the slugs should be held against the surface portions of the backing member which they cover in such a way as effectively to exclude air from such surface portions during heating of the billet prior to hot rolling. and during the initial stages of hot rolling and until the facing members are elongated to cover the thus protected surface portions.

When the billet has been heated and is passed through the hot rolling mill the facing members are longitudinally extended to a greater degree than the backing member and, as above indicated, the original lengths of the facing and backing members are determined so that at the end of the rolling they will be of substantially the same length. When the facing members begin to elongate relatively to the backing member they displace or push the slugs ahead of them and the slugs ultimately leave the billet and drop down onto the floor. Due to the shortness of the slugs in the longitudinal direction there is relatively little friction holding them in place and hence they are subject to ready displacement by the facing members when the latter diflerentially elongate relatively to the backing member.

The positioning of the slugs on the billet depends upon the type of rolling mill used and the manner of rolling. In some hot rolling mills the opposed rolls do not in all passes rotate at such speed that the peripheral speeds of the opposed roll surfaces engaging the work are equal. Sometimes the work is passed back and forth between rolls so that the forward end of the work in the first pass is the trailing end in the second pass. Depending upon the conditions of rolling it may be desirable to provide the slugs 6 at opposite ends of the billet as shown in Figure 2. This is done when the tendency of the rolls during hot rolling is to elongate one of the facing members in one direction relatively to the backing member and the other facing member in the opposite direction relatively to the backing member. The conditions determining the position of the slugs is readily determinable by those skilled in the art for any given mill and rolling procedure.

Figure 3 shows a modified form of structure which is identical with that shown in Figures 1 and 2 except that both slugs are at the same end of the billet. In Figure 3 parts corresponding to the parts shown in Figures 1 and 2 are identified with the same reference numerals each with a prime affixed. A billet of the type shown aaeaoai in Figure 3 wouldbe used when the upper and lower rolls in the hot mill rotate at such speeds that the opposed roll surfaces engaging the work operate at the same peripheral velocity and when the tendency is to elongate both facing members in the same direction relatively to the backing member Figure! shows in which parts corresponding to the parts shown in Figures 1, 2 and 3 are identified by the same reference numerals 'each with a double prime amxed. In Figure 4 a, slug 6" is employed only on the top of the billet, the lower facing member 4" being of the same length as the backing membar 2'. Such a structure may be employed, for

example, when dissimilar facing members are used. The facing member 4" may be of a metal having a longitudinal extensibility substantially the same as that of the metal of the backing member 2". For example, a bimetallic billet having a. backing member of ordinary steel and a facing member of stainless steel may have both of such members of substantially the same length as they will elongate to approximately the same extent when the bimetallic billet is hot rolled. The billet shown in Figure 4 may have the backing member 2' of ordinary steel, the facing member 3" of gliding metal, the facing member 4" a further modified structure" of stainless steel and the slug 8" of any readily length of such members and consequently also in the length of the slugs.

The slugs when applied should be pressed firmly against the ends of the facing members with which they respectively cooperate. The slugs will ordinarily be sheared from bars and I find that the shear fins on the slugs are useful as providing mean tending to embed themselves to some extent in the ends of the facing members, thus forming a sufliciently airtight seal at the junction between each facing member and its adjacent slug. If desired the slug maybe struck toward the cooperating facing member with a hammer or other tool when applied. If a slug should slip during peining of the flange of the backing member against the edges of the facing members and slugs it can ordinarily bedriven back into proper position even after peining.

While I have shown and described certain present preferred embodiments of the invention and certain present preferred methods of practicing the same, it is to be distinctly understood that the invention is not limited thereto but may beotherwise variously embodied and practiced within the scope of the following claims.

I claim:

1. A method of preparing and rolling a bimetallic billet comprising forming billet components having different longitudinal extensibilities upon rolling of the blmetallc bllet so that a component having a relatively great longitudinal extensibilit5 is shorter than a component having a relatively small longitudinal extensibility, assembling said components so that the first mentioned component covers only a portion of an opposed face of thesecond mentioned component. leaving another of said face to protect the same against oxidation, heating the bimetallic billet formed by assembly of said components and rolling the heated billet so that the first mentioned component is longitudinally extended relatively to thesecond mentioned component to cover said originally exposed portion of said face thereof. 5

2. A method of preparing and rolling a. bimetallic billet comprising forming billetcomponents having different longitudinal extensibilities upon rolling of the bimetallic billet so that a component having a relatively great longitudinal extensibility is shorter in the direction of rolling than a component having a relativelysmall longitudinal extensibility, assembling said components, fastening over a portion of the second mentioned component not covered by the first mentioned component upon assembly of the components a protective device to protect such portion against oxidation, heating the bimetallic billet formed by assembly of said components and rolling the heated billet so that the first mentioned component is longitudinally extended relatively to the second mentioned component to displace and separate from the billet said protective device and cover said portion of the second mentioned component.

3. A method of preparing and rolling a bimetallic billet comprising forming a billet component relatively long in the direction of rolling and a billet component relatively short in the direction of rolling of metal having a greater longitudinal extensibility upon rolling of the bimetallic billet than the metal of the relatively long component, assembling said components and deforming at least one thereof whereby to hold them together, fastening over a portion of the first mentioned component not covered by the second mentioned component upon assembly of the components a protective device to protect such portion against oxidation, heating the bimetallic billet formed by assembling of said components and rolling the heated billet so that the second mentioned component is longitudinally extended relatively to the first mentioned component to displace said protective device and cover said portion of the first mentioned component. i

4. A method of preparing and rolling a bimetallic billet comprising forming a flanged backing member relatively long in the direction of rolling and a facing member relatively short in the direction of rolling ofmetal having a greater longttudinal extensibility upon rolling of the blmetallic billet than the metal of the backing member, assembling the backing and facing members and deforming flange means of the backing-member to hold the facing member thereto, positioning over a". portion of the backing member not covered by the facing member upon assembly of the members a protective device to protect such portion against oxidation, holding the protective device in place by flange means of the backing member, heating the thus assembled members and rolling the same so that the facing member is longitudinally extended relatively to the backing member to cover said portion of the backin member.

or metal having relatively great longitudinal extensibillty upon rolling of the bimetallic billet. said components being held together. and a metal protective device separate from the second mentioned component disposed in longitudinal hlignment with the second mentioned component connected with the first mentioned component and covering a portion thereof not covered by the second mentioned component upon assembly of the components to protect such portion against oxidation.

6. A bimetallic billet comprising a flanged steel backing member and a facing member or relative-! 1! soft metal and oi less thickness and shorter than the backing member lying against the backing member and held thereto by flange means of the backing member and a metal protective device separate from the facing member disposed in longitudinal alignment with the facing member and also held to the backing member by said flange means and covering a portion oi the backing member not covered by the facing member upon assembly of the members to protectgsuch portion gainst oxidation. I

7. A bimetallic billet comprising a flanged steel backing member and opposed lacing members of gliding metal of less thickness than the backing member lying against opposed faces 0! the backing member and held thereto by flange means of the backing member. at least one or the facing members being shorter than the backing member. and a metal protective device disposed in iongitudinal alignment with a lacing member which is shorter than the backing member, said metal protective device being separate from such facing member and held to the backing member by at least certain 0! said flange means and covering a portion of the backing member not covered by such facing member upon assembly of the members to protect such portion against oxidation.

WILLIAM A. CARLSON.