US2626458A - Process for making clad metal - Google Patents

Description

Jan. 27, 1953 L. J. LIEBERMAN 2,626,453

PROCESS FOR MAKING GLAD METAL Filed March 29. 1949 9 Sheets-Sheet l D I INVENTOR Jan. 27, 1953 J. LIEBERMAN 2,626,453

PROCESS FOR MAKING cum METAL Filed March 29. 1949 9 Sheets-Sheet 2 Jan. 27, 1953 L. J. LIEBERMAN 2,626,458

PROCESS FOR MAKING CLAD METAL Filed March 29. 1949 Jan. 27, 1953 Filed March 29, 1949 L. J: LIEBERMAN PROCESS FOR MAKING CLAD METAL 9 Sheets-Sheet 5 I INVENTOR Zea Jlzizmzz &3 nJE! Q;

ATTO R N EYS Jan. 27, 1953 L. J. LIEBERMAN PROCESS FOR MAKING GLAD METAL 9 Sheets-Sheet 6 Filed March 29. 1949 INVENTOR lam Jlz'aermaa Jan. 27, 1953 J. LIEBERMAN PROCESS FOR MAKING CLAD METAL 9 Sheets-Sheet 7 Filed March 29. 1949 INVENTOR ATTO R N EYS J 1953 J. LIEBERMAN 2,626,458

PROCESS FOR MAKING CLAD METAL Filed March 29, 1949 9 Sheets-Sheet 8 I'NVENTOR BY um). I

' ATTORNEYS Jan. 27, 1953 L. J. LIEBERMAN 2,626,458

PROCESS FOR MAKING CLAD METAL Filed March 29. 1949 9 Sheets-Sheet 9 104 44 59: 9 I f" IOZ 54 I lp g I II ll I "III l l 'ln ll lll l Patented Jan. 27, 1953 UNITED STATES PATENT OFFICE 4 Claims.

The present invention relates to the manufacture of clad metal.

The present application is a continuation-inpart of my application Serial No. 5,427, filed January 30, 1948, for Clad Metal. Claims on the composite are contained in the parent application. The species claim relating to the process of Figures 27 to 33 inclusive, are embodied in divisional application Serial No. 163,975, filed May 24, 1950, for Clad Metal. The claims on the blanks are included in divisional application Serial No. 163,976, filed May 24, 1950, for Clad Metal.

A purpose of the present invention is to simplify and facilitate the incorporation of nonhomogeneous ingredients such as abrasive in the surface layers of clad metals, or produce plates or sheets made up entirely of metal mixed with non-homogeneous ingredients such as abrasive.

A further purpose i to permit the rolling of layers of metal particles which initially exhibit little ductility without the development of serious cracks and breaks in the work under the rolls.

A further purpose is to accomplish the compacting, welding, bonding, reduction in thickness and sintering of powder metal layers by hot rolling, while protecting against breakage throughout the rolling operation.

A further purpose is to clean one side of each of two weldable or fusible metallic backings, applying a layer of weldable or fusible metal particles to the clean side of each backing, bring the backings together with the layers between them and separate from one another, join the backings around the edges to make composites, soak the composites at hot rolling temperature, and. hot roll the composites to eliminate porosity in the layers, Weld the metal particles of each layer, bond each layer to its backing and reduce the thickness.

A further purpose is to interpose a confining and parting sheet between the layers and preferably to unite the sheet to the backing so that one backing and layer may be inverted and superimposed on another without having that layer drop away from the upper backing.

A further purpose is to make up the particle layers of a mixture of weldable or fusible metal particles with abrasive or refractory non-metalllc particles. 4

A further purpose is to place a rim around each backing on the clean side, place the backing with the rims and clean sides uppermost, insert the layers of particles into the space defined by the rims against the clean sides of the backings, place a parting sheet over one layer and backing, unite the sheet at its edges to the rim, invert the backing and layer provided with the parting sheet, superimpose it on the other backing above its layer and rim, and then unite together the rims around the outer edge.

A further purpose is to partially assemble the composite, providing a lateral opening, to insert the metallic particles with or without abrasive through the lateral opening, to close the lateral opening and to roll the completed composite at hot rolling temperature.

A further purpose is to partially assemble the composite with openings in one lateral face, to vibrate the composite and concurrently to insert metallic particles with or without abrasive into the composite during vibration.

A further purpose is optionally to compact the particles before the composites are completed and optionally to sinter the particles before they are placed in the composites and after compacting.

A further purpose is optionally to compact the particles by pressure applied to the layer against the backing and confined by the edges by the rim.

A further purpose is to make the backing and permissibly also the metallic particles of constructional iron alloy containing not over 0.55 per cent carbon.

A further purpose is optionally and preferably to employ the layers of particle in the composites in loose uncompacted form.

A further purpose is to employ backings and optionally to employ layers having stainless steel for the backings and the metallic particles of the layers.

A further purpose is to use particles which range between 6 and 100 mesh per linear inch for the abrasive and between 6 and 300 mesh per linear inch or finer for the metal particles.

A further purpose is to employ between 2 and 50 per cent, preferably between 10 and 30 per cent, of abrasive, in the abrasive layer.

A further purpose is to use an abrasive containing layer which comprises from 5 to of the total plate or steel thickness.

Further purposes appear in the specification and in the claims.

In the drawings I have chosen to illustrate a few only of the various embodiments in which my invention may appear, choosing the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear dem- Figure 2 is an enlarged diagrammatic section of the abrasive particles which are used.

Figure 3 is an enlarged diagrammatic section of the mixture of metal particles and abrasive particles which is employed.

Figure 4 is a diagrammatic axial section of a rotary mixer in which the mixing may be accomplished.

Figure 5 is a top plan view of one of the backings looking at the clean side.

Figure 6 is a side elevation of Figure 5.

Figure '7 is a top plan view of a backing to which the rim has been applied.

Figure 8 is a side elevation of Figure 7.

Figure 9 is a top plan view showing the backing and rim with the layer of particles applied inside the rim.

Figure 10 is a top plan view of a parting sheet.

Figure 11 is a side elevation of Figure 10.

Fi ure 12 is a diagrammatic side elevation showing two backings and layers, one of which has been provided with a parting sheet and is superimposed above the other to combine in making a composite.

Figure 13 is a side elevation of a completed composite.

Figure 14 is a diagrammatic sectional view of a soaking pit in which the composites have been placed.

Figure 15 is a diagrammatic side elevation of a composite undergoing hot rolling.

Figure 16 is a diagrammatic fragmentary plan view of a completed composite which is rolled down and is about to be trimmed around the edges as shown.

Figure 17 is a diagrammatic partially sectional side elevation of a backing sheet and rim showing the application of a flux.

Figure 18 is a view corresponding to Figure 17 showing the application of a deoxidant.

Figure 19 is a fragmentary diagrammatic central vertical section showing pressing of particles.

Figure 20 is a diagrammatic central vertical sectional view of a sintering furnace.

Figure 21 is a top plan view of a modification showing the layer made up of compressed biscuits.

Figure 22 is a diagrammatic partially sectional side elevation of a variation showing pressing of the layer applied directly to the backing.

Figure 23 is a fragmentary side elevation, partly in section, of a variation in the composite.

Figure 24 is an enlarged diagrammatic transverse section of the complete composite showing the mounting of a single abrasive particle.

Figure 25 is a top plan view of the completed composite showing the abrasive surface.

Figure 26 is an enlarged transverse sectional view showing the bond line of the clad metal.

Figure 2'7 is a diagrammatic end elevation illustrating a modified procedure for insertion of the particles.

Figure 28 is a diagrammatic side elevation of the vibrating table of Figure 27, omitting the other structure.

Figure 29 is a top plan view of the composite shown in Figure 27 at the time of filling, omitting the funnel.

Figure 30 is a side elevation of the composite of Figure 29 after the final rim bar has been inserted.

Figure 31 is an end elevation of Figure 29 showing the funnel in more detail.

Figure 32 is a top plan view of a composite similar to that shown in Figure 29 but illustrated in variation.

Figure 33 is a side elevation of the rim bars and parting sheet of Figure 29, showing the manner of attaching the parting sheet, but illustrating a variation in the arrangement of the rim bars.

In the drawings like numerals refer parts throughout.

In the prior art efforts have been made to produce floor plate and the like in which nonhomogeneous particles such as abrasive (including refractory) are distributed or embedded in metal, by casting molten metal around the abrasive particles and employing the product in the form as cast. Difficulty has been encountered because of the tendency of the abrasive or the like to segregate due to diiference in specific gravity and because of the limited utility possessed by the structure when used in the as cast form.

EiTorts have also been made in the prior art to apply a layer of metallic particles, for example a bearing layer, on a backing strip, and to apply rolling pressure directly to the layer and strip. The ability to reduce the thickness of the section has been limited to compacting of the particles, as the application of substantial rolling pressures as employed in hot rolling has not been possible without breakage of the layer of particles due to the limited ductility.

By the present invention it has been possible to obtain clad metals which can undergo normal reductions in hot and in some cases in cold rolling and permit the production of sheet and plate having rolled clad layers containing nonhomogeneous ingredients such as abrasive, and having the properties in the backings normally secured in similar hot and cold rolled metals. It is likewise possible by the invention to obtain any convenient alloy or composition in the clad layer, without the difficulty which is otherwise encountered in rolling clad material of dissimilar characters.

The layer which is incorporated by cladding will suitably mainly comprise powdered metal which is capable of welding to itself and to the backing layer. For many purposes the composition of the layer to be applied on the backing to like will be constructional iron alloy containing not over 0.55 per cent carbon, such as iron of practically carbonless grade, low carbon steel (for example 0.01 to 0.20 per cent carbon), medium carbon steel (0.20 per cent carbon to 0.55 per cent carbon), low alloy weldable steel (1 to 5 per cent total of hardenability alloying ingredients including any one or more of nickel, chromium, manganese, molybdenum, vanadium, silicon, and the like) and containing carbon up to 0.35 per cent nominal. All of these materials will have the usual metalloids and residual or intentional alloy ingredients which are commonly employed in constructional iron and steel.

If desired the powdered metal may comprise stainless steel, whether of the chrome-nickel grade (for example 18 per cent chromium, 8 per cent nickel nominal) or of the straight chromium grade (for example 16 per cent chromium).

Likewise the powdered metal may be of the copper base alloy type, such as copper, brass, bronze, beryllium copper, or the like. Also the powdered metal may be of the nickel alloy type (such as nickel, Monel, K Monel, inconel, or the like). Where the base metal is of suitable character to weld or fuse therewith the metal products may also be of aluminum, aluminum base alloy, magnesium or magnesium base alloy.

In any case where the metals chosen will weld or fuse adequately with one another and with the base, mixtures of two or more of such metal powders may be employed.

The mesh sizes for the metal particles may vary considerably, particularly as plastic flow occurs under rolling conditions and the individual particles lose their identity. Good results can be obtained with mesh sizes ranging between 6 and 300 mesh per linear inch or finer, particles finer than 100 mesh per linear inch being employed if the expense is justified. For satisfactory commercial results mesh sizes between 30 and 100 mesh per linear inch are usually quite adequate.

Figure 1 shows metal particles 40 of the character that will be employed.

The abrasive, where abrasive is used, will preferably be a refractory abrasive which will retain the form of discreet unmolten particles during hot rolling. For this purpose non-metallic refractory particles such as alumina, silica, magnesia, chrome iron ore, zirconium dioxide and silicon carbide are very satisfactory.

The sizes of the abrasive particles for good results should range between 6 and 100 mesh per linear inch, preferably between and 60 mesh per linear inch.

While certain aspects of the invention are useful without employing abrasive particles, for the manufacture of floor plates and the like it is best to employ between 2 and 50 per cent of abrasive particles based upon the totalof metal plus abrasive particles. For ordinary commercial purposes the most satisfactory range is between 10 and 30 per cent. Unless otherwise stated, all percentages given herein are by weight.

Figure 2 shows abrasive particles 4| of the character which will be employed. No attempt is being made to show the actual contours of the particles.

The abrasive particles will conveniently be mixed with the metal particles to achieve a homogeneous mixture 42 as shown in Figure 3. While the mixing can be done by hand or by any suitable means, such as sifting together through screens, a rotary mechanical mixer 43 is most satisfactory in production.

The backing metal will initially be in the form of an ingot, billet, slab or plate of any suitable dimensions, preferably of the same general proportions as are normally employed at the beginning of hot rolling of the particular backing. Any one of the metals already referred to in reference to the metal products may be used for the backing metal provided the metal of the backing will adequately weld with the metal of the metal particle layer. For most commercial purposes the backing will be employed as a structural member, and therefore constructional iron alloy containing not in excess of 0.55 per cent of carbon will be best in most cases. While carbonless iron can be used, the advantage of increased physical properties will normally lead to the use of low or medium carbon constructional steel or low alloy weldable steel of the compositions already explained in connection with the powdered metal. For special applications stainless steel as already described may be employed, as well as the copper group of alloys (copper, brass, bronze, beryllium copper and the like) or the nickel group of alloys (nickel, Monel, K Monel, inconel and the like). Where the powdered layer will adequately weld therewith the backing metal may also be aluminum or aluminum alloy or magnesium or magnesium alloy.

The backing 44 as shown in Figures 5 and 6 is conveniently rectangular in major dimensions and often will have a thickness in the range between 1 and 12 inches, preferably about 2 inches. A convenient size for each of the other dimensions is 10 to 96 inches or greater.

In some cases a flux may be desirable, although ordinarily it has been found by the present inventor that a flux is not necessary. The flux or bonding layer if used will vary with the nature of the metal powder and the backing metal as well known, and no attempt will be made to review all of the known fluxes or bonding layers which might be employed. With nickel and chromium alloys generally, comprising either the metal powder or the backing, when the other member is iron or steel, nickel flake has proved to be very satisfactory as flux. Nickel flake is suitable with the various grades of stainless steel. When copper base alloy forms one or both of the members to be bonded, any good bronzing flux is suitable.

Where iron or steel is to be bonded to iron or steel, particularly where one of the alloys contains substantial amounts of chromium or nickel, an electrodeposited or sprayed layer of iron or nickel may to advantage be used, in accordance with Houston, U. S. Patents 2,225,868 and 2,147,407, and Armstrong, U. S. Patents 2,044,742 and 1,997,538.

It has been found that in most cases the use of a deoxidant is not necessary, especially as the metal powder has a large surface and comparatively large amounts of oxygen can be present without serious consequence. This is a distinct advantage of the present procedure over the prior practice of bonding a sheet to a backing layer. Where a deoxidant is used, aluminum or magnesium powder, metallic calcium or sodium or a hydride such as calcium hydride may be employed to advantage.

In accordance with the present invention the powder layer is applied to the backing layer by making up composites. The mating face of the backing layer should be thoroughly cleaned and for this purpose the surface 45 to be welded or fused is preferably shot blasted. Other cleaning techniques may be used whether by mechanical abrasion for example through grit or sand blasting, or chemical removal as by pickling or electrochemical removal as by electrolytic etching. Whatever cleaning step is employed, the resulting surface should be clean and dry.

On the clean surface around the edge of the backing a rim 46 is applied, conveniently by welding or fusing. If substantial delay or soilage is to be involved in the technique of applying the rim, the cleaning of the surface at 45 should be accomplished after applying the rim, but if the application of the rim is carefully controlled, the cleaning can be accomplished prior to the application of the rim. The rim is best made by applying side members 41 and end members 48 conveniently of rectangular (preferably approximately square) cross section, suitably of the same composition as the backing and welded or fused to the backing at 49 all around the periphery and at 50 where the various ends meet. The welding may be continuous or dicontinuous and no serious harm is done by slight gaps or porosity in the weld as long as there is secure anchorage between the rim and the backing. Optional vent holes 5| may be provided extend- 7 ing through the rim to permit escape of interior gases.

The backlngs after being provided with the rims are filled with the layers of particles against the clean sides. This is best accomplished by placing each backing with the clean side and rim uppermost and depositing the desired particle composition 52 in the space defined by the rim on top of the clean surface 45. While as later explained these particles may be previously compacted and even previously sintered in the perferred embodiment, the particles applied at 52 will be entirely loose and uncompacted as indicated at Figure 9 and will preferably fill the space up to substantially the top of the rim.

The backings with the layers of particles will be employed in sets, each set preferably consisting of a pair. One of the backings with its rim and particle layer will conveniently be left resting upright as shown at 53 in Figure 12 while the other backing of the pair will conveniently be inverted after being closed by a parting sheet. The parting sheet 54 as shown in Figures 10 and 11 may conveniently be a metal sheet of the same material as the backing, coated on its opposite sides or faces at 55 and 56 with a parting material which extends nearly to the edges but preferably is omitted in a band 51 around the edges on each side, to aid in welding. The parting material may conveniently be a refractory such as magnesia, alumina, chrome iron ore, ferric oxide, or the like, made into a paint with a vehicle such as shellac, linseed oil or turpentine and painted on and allowed to dry. The separator is placed on the rim of the backing which is to be inverted and conveniently fastened as by tack welding at 58 around the edges. The separator then performs the function of a closure to permit inverting the backing 59 (Figure 12) without permitting the particle layer to drop out. The separator also performs the function of parting the rolled product as later explained.

When the composite is finally assembled as shown in Figure 13, it has backings on the outside (top and bottom) with clean surfaces directed inwardly and toward one another, a layer of particles against each clean surface and within a confining rim and a parting sheet between the respective layers which are otherwise adjoining. The rims are then joined around their edges, preferably by a weld 60 which bridges over the space occupied by the parting sheet and joins the backings by joining the rims.

The composites are then soaked at hot rolling temperature following the usual procedure for soaking preliminary to hot rolling of the metals involved.

In Figure 14 a conventional soaking pit BI is shown containing composites 62 which are placed on end after the manner of soaking ingots and billets. partially sintering the particles together, beginning the process of uniting the particles to one another and to the backing which is carried forward and completed during the hot rolling. Where iron and steel are involved, the soaking time will preferably be from 2 to 4 hours at temperatures of 1800 to 2400 F., preferably 2000 to 2400 F., and most desirably 2250 to 2400 F. Of course, the soaking temperature must not be high enough to melt any component, and if any metallic component melts at the lower limit of the hot rolling temperature of another metallic component, the present process will not be applied to such components in such combination.

The soaking has a definite effect in Experience has indicated that no special soaking precautions are required other than those indicated for the metals employed.

The composites are rolled, following the usual rolling procedure for the metal of the backing. For iron and steel, blooming and heavy duty plate mills are most suitable. The hot rolling performs a number of different functions. In the first place it accomplishes a function similar to pressing, eliminating porosity and compacting the particles without the necessity and the expense and delay incident to pressing on a conventional powder metallurgy press. At the same time, as porosity is eliminated and the particles form a dense mass, the particles weld to one another and bond to the backing. Thus the action involves the effects of pressing and sintering, and also marked plastic flow which gives much more compacing than would be possible under ordinary pressing and sintering.

As in ordinary rolling practice, the work is widened and elongated, reducing to any suitable gage, for example plate thickness such '1 s /1 or /8 inch, or sheet thickness such as 10 age or lighter. Thus in a particular example, an initial area of 18 to 20 inches was increased to 40 by 100 inches during the rolling and an initial thickness of 1 inches was reduced to 6 inch. The abrasive containing layer will often be 5 to of the final thickness, usually 20 to 50%. The hot work can be followed by cold work so far as the ductility will permit. During the first pass or first few passes, air in the interior space between the particles of the layers and in other voids escapes through the vent holes 5| already described, if they are used, but the vent holes are then pinched closed or substantially closed and no tendency is noted to draw in air during any later point in the rolling process.

The particles of abrasive go through the rolling without any tendency to segregate and are firmly held in the compacted particle layer which finally results.

In Figure 15 rolling mill rolls 63 are illustrated which are reducing the section at 64 to indicate one of numerous passes which may be used. Cross rolling may be employed if desired. When the product is rolled to gage, the edges are trimmed as by a shear to eliminate the edge strip 65 which will be imperfect due to the rolling down of the rim and the weld beads. The individual sheets are then stripped apart, the separater discarded and the final product consists Of a backing B6 and a face cladding layer 61 thoroughly united and welded at a bond line 68 (Figure 26) and having discrete particles of abrasive 69 throughout the layer 6! and uniformly distributed over the surface as shown in Figure 25. Actually the metal tends to form a layer over the abrasive as shown in enlargement at 10 (Figure 24). Experiments indicate that the bond to the backing is excellent and the product will undergo flanging, bending and other normal forming without separation of the bond or breakage of the clad face. Unlike the cast products of the prior art, the face layer can wear clear through to the bond line without encountering any difference in the distribution of the abrasive or other added particles. Of course, it will be evident that where desired the particle layer may be made up of several particle layers with different compositions, in which case the percentage of abrasive or other nonmetallic ingredients may vary if desired from top to bottom.

The invention is applicable wherever clad metals are to be made, since it overcomes the difficulty in rolling dissimilar metals and permits the adding of a facing layer having disadvantageous hot rolling characteristics at the temperature required for hot rolling of the backing. Thus for such purposes the composition as shown at 52 in Figure 9 may be entirely metal particles without abrasive or other added material.

In most cases the invention will, however, find its best application in making floor plates, and products of this character are widely used in stairway treads and'landings, floors, vestibule floors, railroad car steps, fire escape floors and steps, kitchen floors, machine and industrial walkways, and running boards for box cars.

The following may be cited as examples:

Example I The backing is plain carbon steel of AISI 1020 grade, and the particle layer consists of 80 per cent of powdered steel of AISI 1010 grade and 6 to 300 mesh per linear inch and 20 per cent of alumina particles of 6 to 100 mesh per linear inch.

Example II Example II is the same as Example I except that the powdered abrasive is magnesia.

Example III Example III is the same as Example I except that the powdered metal is stainless steel of composition 18 per cent chromium and 8 per cent nickel, nominally no carbon.

Example IV Example IV is the same as Example I except that the abrasive makes up 30 per cent of the particle layer.

Example V Example V is the same as Example I except that the backing is low alloy weldable steel of nominal composition 0.40 per cent molybdenum, 0.50 per cent nickel, 0.60 per cent manganese, and 0.30 per cent carbon.

Example VI Example VI is the same as Example I except that the particle layer is 100 per cent plain carbon steel of AISI 1020 grade.

Example VII Example VII is the same as Example I except that the particle layer is 100 per cent of stainless steel, nominally 18 per cent chromium, 8 per cent nickel, no carbon.

Example VIII Example VIII is the same as Example I except that the metal particles consist of brass containing '70 per cent of copper and 30 per cent of zinc.

Example IX Example IX is the same as Example I except that the metal particles consist of bronze containing 90 per cent of copper and 10 per cent of tin.

Example X Example X is the same as Example I except that the metal particles consist of Monel.

Example XI Example X! is the same as Example I except that the particle layer consists 100 per cent of inconel.

Example XII Example XII is the same as Example I except that the backing and metal particles consist of 24 S aluminum alloy.

While for many purposes it is preferred to apply the particles as loose uncompacted powder which is compacted by the rolling, to omit flux and omit deoxidant, and avoid sintering prior to soaking, these features may optionally be used in individual cases.

Figure 17 illustrates the use of flux H, in this case nickel flake, applied to the clean surface of the backing before introducing the layer 52 of metal particles usually with abrasive.

Likewise there is shown in Figure 18 the application of a deoxidant layer 72 preferably on top of the particle layer 52. The deoxidant layer in this case may be aluminum powder where the particle layer consists of steel powder with a'brasive.

While as already explained the rolling will ordinarily perform the pressing function and avoid the expense of pressing, the particles may be formed at 13 (Figure 19) into a biscuit or briquette prior to introducing them into contact with the clean surface of the backing. Where preforming is employed, the surface of the particle layer which is to come into contact with the clean surlace of the backing should be cleaned as by shot blasting prior to contact. Any conventional press M may be employed in pre-'- forming.

The preforming pressure will preferably be of the order of 1000 to 10,000 pounds per square inch. The preformed particles may also be sintered prior to making the composite if desired. A sintering furnace 15 is illustrated, heated electrically at T6 for sintering particle layers 17 permissibly in an inert or preferably reducing atmosphere at 18 applied through connections #9. Suitable gases are hydrogen, carbon monoxide, nitrogen, ammonia, helium or argon or mixtures thereof. The surface of the sintered layer which is to come into contact with the clean surface of the backing should be cleaned as by shot blasting before the composite is assembled.

Sintering may be accomplished with or Without pressing. For the present purpose a loose mass of particles may be sintered.

For iron or steel the sintering temperature may range between 1200 and 1800 F. permissibly up to 2400 F. and preferably at about 1550 F. preferably for a time of one and one-half to three hours. Where an inert or reducing atmosphere is used, the layers should cool in the atmosphere.

In case pressing is to be employed, it is very expensive to use large presses, and individual biscuits or briquettes as shown in Fig. 21 may be assembled inside the rim of the backing to form the particle layer. It has been found that these weld perfectly along their lateral edges during rolling, provided such edges are cleaned before making up the composite.

Where pressing is to be employed, the backing and rim may form part of the mold as shown in Figure 22. In this case the press 8| has a die 82 which just fits within the limits of the rim and brings pressure against the backing held 11 in a suitable cooperating die 83. The pressing may take place in steps, adding more particles as the layer is compacted.

While for many purposes the most convenient form of the invention will employ two backings and two particle layers in the composite, it will be understood that any plurality of backings and layers may be used preferably in multiples of two. Figure 23 illustrates a composite made up of four backings 84, 85, 86 and 81 each with a particle layer adjoining. Where the two backings 85 and 86 would otherwise be juxtaposed, an additional parting sheet 88 is applied and the edges of the backings are welded at 89.

In the description of the prior forms of the invention, the backing sheets have not been brought together in the composite until after the metalllc particles to make up a cladding layer have been inserted. In many instances it will be preferable to assemble the composite more nearly completely beiore the metallic particles are introouced, thus gaining the advantage of edge filling, and avoiding the operation of spreading the particles over the backing.

It has been found that by this procedure it is possible to apply the parting compound on the parting sheet more economically since the workman does not have to exercise special care to avoid spreading over the part, where it would interfere with bonding. It also has been found that by the present variation the amount of welding can be markedly reduced, and therefore the cost of making the composite can be decreased. On actual experiment, it is found that the time required for filling is cut in half by the employment of edge filling, and the cost of filling is correspondingly reduced.

In edge filling, it is preferred to place the composite on a vibrating table or otherwise impact the composite during filling of the cladding particles, in order to assure adequate compacting of the particles.

As shown in Figure 27, the composite is completed except for closing the upper edge, and in this form constitutes an edge-open double container 90 having its open edge 9I uppermost and supported by a harness 92 in upright position on a table 93, which, as shown in Figure 28, is fulcrumed at 94 at one end and vibrated at the opposite end by earns 95 on a shaft 96 rotatin in bearings 91.

To aid in filling, a funnel 98 is suitably placed above both of the edge openings of the composite, and the mass of metallic particles of any of the compositions as above described, with or without abrasive, is inserted through the funnel and allowed to compact in the cavities of the composite under the tamping or vibrating of the table.

In making up composites for edge filling, it has been found that substantial economies can be accomplished.

As best seen in Figure 29, the backings 44, suitably prepared for adhesion, are joined together by a rim 46 consisting of individual bars 99 extending the full distance from one backing to the opposite backing. The rim is then joined to the respective backings by two peripheral welds I and II, eliminating the necessity of extra welding required in the forms previously described.

In this instance the parting sheet 54 does not extend fully to the periphery of the composite, but extends only to the inside of the rim and is 12 tack welded or otherwise suitably united to the rim at the inside at points I02.

Prior to filling, the composite is assembled as shown in Figure 29, but the topmost rim bar 99' is omitted, thus leaving two open cavities I03 and I04 each defined by a backing at one side and the parting sheet at the other side, and portions of the nm at the bottom and ends.

After completion of filling, the top rim bar 99' is inserted and welded in the position indicated in Figure 30.

It will be evident of course that the major welds I00 and IIII which run around the periphery may be applied to the lateral ends and bottom before or after filling as desired, but if these major welds are not to be completed until after filling, the structure will preferably be well held together by tack welds or clamps prior to that time.

It is best to have the funnel 98 extend down on either side of the parting sheet, whether or not the parting sheet terminates at the inside of the rim or extends to the periphery, and therefore, as shown in Figure 51, the funnel desirably has a central slot I05 for receiving the upper end of the parting sheet.

In some cases it may be preferable to grip the parting sheet more firmly than is possible in the :torm of Figures 29, 30 and 31, and for this purpose the form of Figure 52 is employed, in which the parting sheet runs clear to the periphery as in the forms earlier described. In this case the two separate rims IuIi and Ill! extend over the bottom and the lateral ends, but the top is left on to provide access for welding. Welds in this case are required at I08, I09, and Ill], thus requiring more welding than in the form of Figure 29.

One advantage of the procedure described is that the parting sheet is accessible for application of parting compound on both sides after it has been welded to the rim or rims in the forms of Figures 29 and 3 This is illustrated in Figure 33, where the rim has been assembled except for one edge and the parting sheet is ready to receive a coating of parting compound on both faces. The workman can readily apply this coating without special care, with no danger of inadvertently applying the coating to the backing.

The form of Figure 33 indicates the possibility of extending individual rim bars fully to the periphery at III, so that the rim bar or bars last inserted need not run the full width of the composite.

It will be evident that by the present invention it is possible cheaply and conveniently to fabricate clad metal sheets containing nonhomogeneous material such as abrasive, and to roll out, compact, weld and bond metals which otherwise are diflicult to roll and impossible to reduce to thin layers as required for clad metals.

While the invention has its widest application in the making of fioor plates it will be understood that the principles of the invention can be used in many of the connections where it otherwise would be diificult to unite together the particular combination of metals which is employed.

When reference is made to the particles or layers as being welded, it will be understood that they may be fused.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the process and product shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. The process of making clad metal having a powder metal compact on one face, which comprises mixing weldable metal particles with refractory non-metallic particles, cleaning one side of each of two weldable metallic backings, placing a rim around each backing on the clean side, placing the backings with the rims and clean sides uppermost, applying a layer of the mixture to the clean side of each backing, securing a confining and parting sheet to the rim of one backing above the layer, inverting that backing and layer and superimposing it on the other backing and layer with the parting sheet adjoining the two layers to make composites, soaking the composites including the layers at hot rolling temperature, and hot rolling the com posites to eliminate porosity in the layers, weld the metal particles of each layer, secure the abrasive particles, weld each layer to its adjoining backing and reduce the thickness.

2. The process of making clad metal having a powder metal compact on one face, which comprises mixing weldable metal particles with refractory non-metallic particles, cleaning one side of each of two weldable metallic backings, placing a rim around each backing on the clean side, placing the backings with the rims and clean sides uppermost, applying a loose non-compacted layer of the mixture to the clean side of each backing, securing a confining and parting sheet to the rim of one backing above the layer, inverting that backing and layer and superimposing it on the other backing and layer with the parting sheet adjoining the two layers, joining the backings around the edges to make composites, soaking the composites including the loose noncompacted layers at hot rolling temperature and hot rolling the composites to eliminate porosity in the layers, weld the metal particles of each layer, secure the refractory particles, weld each layer to its adjoining backing and reduce the thickness.

3. The process of making clad metal having a powder metal compact on one face, which comprises mixing together weldable metallic particles and abrasive non-metallic particles, making up a composite of two weldable metallic backings, spaced by a layer of the mixture of weldable metallic particles and abrasive non-metallic particles adjoining the inside of each backing and by a parting sheet between the layers of particles, with a rim joining the backings and surrounding the edges of the layers of particles, soaking the composite at hot rolling temperature, and hot rolling the composite to eliminate porosity in each layer, weld each layer to its adjoining backing and reduce the thickness.

4. The process of making clad metal having a powder metal compact on one face, which comprises compacting weldable metallic particles into a briquette, making up a composite of two weldable metallic backings spaced by the briquettes of weldable metal particles adjoining the inside of each backing and by a parting sheet between the briquettes of weldable metal particles, with a rim joined to the backings and surrounding the edges of the briquettes, soaking the composite at hot rolling temperature and hot rolling the composite to eliminate porosity in each layer, weld the metal particles of each layer, weld each layer to its adjoining backing and reduce the thickness.

LEON J. LIEBERMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1 642,157 Russell Jan. 30, 1900 1,469,761 Yunck Oct. 2, 1923 2,159,043 Orr May 23, 1939 a? 2,179,527 Wellman Oct. 31, 1939 l? 2,225,868 Huston Dec. 24, 1940 91% 2,381,941 Wellman Aug. 14, 1945 2,390,452 Mudge Dec. 4, 1945 29 r 2,431,411 McKee Nov. 25, 1947 1? r/ 2,438,759 Liebowitz Mar. 30, 1948 1 2,446,692 Collins Aug. 10, 1949 M FOREIGN PATENTS Number Country Date 104,277 Australia June 16, 1936 r1

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