US2844229A - Wire-wound brake drum or disc - Google Patents

Description

July 22, 1958 Y M. G. WHITFIELD-v WIRE-WOUND BRAKE DRUM OR DISC Filed March 51. 1955 I AFTER FUSION BEFORE FUSION v INVEYNTOR MARSHALL G. WHlTFIELD United States Paton-t WlRE-WOUNDBRAKEDRUM 0R DISC Marshall G. 'Whitfield, GardentCity, N .1 Y

ApplicationiMar'ch 31, '1955, SeriaINO. 498,150

3Claims. v(Cl. 188-218) This invention relates to composite metalbrakes of the drum or.disc type and, more particularly,tol brake drums or discs capable of dissipatinglarge.amounts of heat without attendant deformation.

In conventional brake drumsemployed in association with internal expandingbrakes, externallytdisposed'fins are often,pro'vided 'to assist indissipating the frictional heat generatedduring'br'aking. In many instances, heat dissipation from fins attached to the'drumis not-entirely satisfactory-due in part .to mechanical. weakness of the means for "fastening the;fin to the drumand, in part, ,to the accumulation of road .dirt between the fins. These disadvantages have been sought to 'be avoided by casting a portion of thebrake'flange on a plurality of endless steel Wire hoops. But the manufacture of'this type of drum does not entirely avoid theuseof fins and such construction is cos'tly and time-consuming, not only requiring the careful placing of a series-of steel wire hoops in a-mold, but also the casting of molten ironundercarefully controlled conditions so asnot to displace'the'hoops. During use, the high-frictional temperatures'developed have a-tendency to loosen the hoops, and their use is of little valueinsofar as heat-dissipating and 'flange-strengthening characteristics are concerned.

It is,-therefore, an important object of this invention to provide an inexpensive composite metal wire-wound brake drum ordisc of-improved strength-which is capable of dissipating or of receiving and storing large quantities of heat without substantial deformation.

Another object of this invention is to provide a relatively light-weight composite-metal brake drum or disc capable of resisting deformation, under heavy-duty .conditions, such drum having one or more plies of. a highstreng'th wire, having a coating-of a highlyheat-conductive-metal,- tension wrapped about and metallurgically bonded to the external surface of the drum onto an internalsurface of the disc.

By the term "*metallurgically bonded is meant that a portion of the fusedmeta'l 'of the coating'on' oneturn .of wire bonds itself to the coating of another turn .and so on. Coating metal on the turns adjacent to'the surface of the drum is bonded both to the drum and'to adjacent turns, thus forming a *highly heat-conductive metal matrix. Preferably, the metal coating on the wire core is either copper or aluminum or an alloy containing copper or aluminum, and such coating, when subsequently fused and bonded withthe ferrous metal of the drum, forms the desired heat-conductive metal matrix. This matrix is capableof receiving large quantities of heat from the drum, storing this heat'brieflyand then dissipating it without injury :to the drum.

Another object of the invention is to provide a relatively light-weight composite metal brake drum composed of -aferrous metal drumhaving ribs or fins on its external circumferential surface and a number of turns of a heatconductive ;metal=coated'ferrous wire wrapped between the ribspor even overthe ribs; the metal coating. on the .2 wires being subsequently fused: to form a continuous heatconductive .matrix which .metallurgically .bonds the wires in situ with oneanother and with the metal of the drum.

An additional object. of the invention is to provide a strong, light-weight vdisctype of brake composed of at least onecircular-flangeof .ferrousmetal, one surface of the flange being. adapted toengage a brake-shoe, and the opposite face being .incontact witha number ofturns of a steel wire having. a highly heat-conductive metal coating; 'such coating being subsequently fusedto form a continuous heatfconductive matrix which metallurgically bonds the wires together and toth'e .fiange-onflanges-of the disc brake.

Yet another object .ofithe .invention .is eto provide a novel method of manufacturing a wire-wound brake drum which is easy and inexpensive -.tov perform. Themethod comprisesitightly wrappingthe external .surface of a ferrous-metal drum with a wire having a highly heat-conductive metal coating anda core. preferably of steel or high strength alloy steel or rn'olybdenum. 'I-hecoating metal on the core is ,preferably copper or aluminum, but-magnesium may also be used. The wound drum is then subjected .to aheating operation at .an elevated temperature to fus'ethe coating,'but.at-.a temperature below the fusing point of the wire core and the ferrous metal brake drum. The metal forming the coating. on the core of the wire is thus fused and'is permitted 'to'flow insuch .a manner as tofill the interstitial spaces .between ..the wires. The molten metal also 'wets the surfaceof .the iron drum and forms'ithe desired metallurgical bond therewith. The steel core of the wire and/the surface of-the irondrum are thus integrally unitedby aihighly. heat-conductive metal matrix.

Examination of the heatet'reateddrum reveals the formation of acontinuousmetal matrix of coating material metallurgicallybonded to both the wire and theperipheral heat-dissipating surface of the drum. This matrix afiords a highly efiicient heat-storing reservoir aswell as a path for facilitating Zthe dispersion of heat awayfrom'the surface of the 'brake drum, to the outermost part of thewire winding.

The above objects, as wellas other features of the inventionywill be'ma'de more apparentas the description proceedsfe'specially when considered in connection with the accompanying drawing, wherein:

Fig. '1 is a partial sectional elevational view of a' wirewound brake"drum embodying the principles of the present invention; and

FigDZ is'an er1larged' sectional view of thebrake drum shown in -Fig. 1, showing 'the relation of the elements before and afterfusion; I 1

Fi'gIS' is a partiahsectional view of a .disc brake embodying-the principles' of ,this invention; and

Fig.' 4=is a partialsectiona'l view of a drum having ridges or fins o'n the externalsur'face thereof and covered with turns 'of'metal 'coate'd wire which are metallurgically bondedtothedrum.

In Fig. l is shown a conventionally castiron or .steel brake drum 10" having a cylindrical drum flange l1 integrally joined at one end thereof wit-hacircular backing plate '12 which is provided 'with a conventional central axle receiving aperture and a series of circularly spaced bolt'holes to permitthe drum 10 to be.secured to anaxle assembly (not shown). The other end .ofthe cylindrical flange 11 may or may not be provided with an annular lip l4 extending generally in a radially outward direction.

The .present invention resides in means for promoting or facilitating the ,transmissionofuheat away from the peripheral surfaceoftthe flange 1-1 of the' brake drum and, if necessary, storing. this heatzbriefly'until it "can be safely dissipated. .For .this -purpose,-.;the :outer surface of the flange 11 is provided with a number of turns of a composite wire which is tension Wound thereabout, the wire 20 defining interstitial spaces 21 therebetween. In accordance with this invention, the composite wire 20 includes a high-tensile strength steel or alloy steel or molybdenum core 22 which is provided with a coating of one or more layers of a metal 24 having a relatively low fusing temperature and a high heat conductivity and which is capable of forming a metallurgical bond with the wire and drum. Aluminum, copper, or magnesium or alloys thereof are examples of suitable coating metals which preferably are used in the practice of this invention. Any number ofturns of composite wire may be applied to the outer cylindrical flange of the brake drum. In the modification shown, two superimposed rows of wire are used, although a larger or smaller number of rows may be used, if desired. A thinner wire 26 composed only of the coating metal may, if desired, be wound between the plies of wire to insure freedom from porosity after the wound structure has been heated to the fusing temperature of the coating metal.

As shown in Fig. 3, the disc brake comprises a circular flanged steel or iron disc 30 having spaced flanges 32, the outer surfaces of which are adapted to engage a brake shoe. If desired, the brake disc may comprise one or a plurality of flange elements, but for purposes of illustration, two flanges are shown. The internal space between the flanges may be partially or completely filled with tenion-wrapped ferrous or molybdenum metal wire 34 having a copper, aluminum or magnesium coating. When the wrapped disc is heated to a temperature above the fusing temperature of the metal coating, the latter fuses and forms a metallurgical bonding matrix uniting the wires and flanges into an integral structure.

In Fig. 4, the ferrous metal drum is provided with a plurality of ridges or fins 42 on the flange 41 thereof. The coated wire is then wound between the ridges and after fusion, the core 22 of the wire is integrally bonded in the matrix 24 in the same manner as previously described in connection with Fig. 1.

Manufacture of the brake drum of the present invention may be accomplished in the following manner. The external surface of the cast iron or steel flange 11 is suitably cleaned, as by wire brushing, pickling or sand blasting, to provide a clean surface capable of forming a metallurgical bond with the metal coating of the composite wire. After cleaning, the surface of the drum may be coated with a thin layer 16 of the same or different metal as that used for the coating on the wire. If a different metal is used, it is one promoting the formation of a durable bond, e. g. tin or mloybdenum, when an aluminum-coated steel wire is used. The outer peripheral surface of the drum is then tightly Wound with one or more layers of the composite wire for a desired number of turns in order to cover the outer surface of the ferrous metal flange partially or completely. Thereafter, the thus wound drum is subjected to a heating operation carried out under suitable conditions to cause the metal coating on the wire to fuse and to fill substantially the interstitial spaces between adjacent turns and plies of wire. If desired, a thin wire of the same metal as used on the coating of the thicker steel or molybdenum core wire may be wound between the turns of such wire, whereby on fusing, a porosity-free metal matrix is formed which provides a path for the rapid conduction of heat away from the ferrous metal drum. Subsequent cooling of the drum causes re-solidification of the fused coating which, in effect, forms a strong integral metallic structure between the wire core and the brake drum flange, such bonding matrix providing a lowresistance pathway for the dissipation of frictional heat.

Preferably, the steel or cast iron drum, after cleaning, may be coated with copper or aluminum to a thickness up to 5 mils. If desired,.a suitable fluxing or brazing compound may be coated on the copper coating to promote the formation of a metallurgical bond with the copper coating.

on the wires. When using aluminum-coated wire, it is desirable to coat the iron base with a film of molybdenum or tin, thereby forming with the aluminum a complex molybdenum-iron-aluminum alloy or a complex tin-ironaluminum alloy. This complex alloy is extremely tough and durable and securely anchors the aluminum matrix to the drum.

Wrapping is preferably carried out by rotating the drum and putting sufiicient drag or tension on the wire so as to generate considerable compressive force in the flange of the drum. This compressive force counteracts the expansive force developed in the drum during normal or heavy-duty braking. In general, during wrapping, the wire is applied with a drag of between 5 and pounds and preferably between 10 and 25 pounds depending on the diameter of the drum and thickness of the wire. The

wire may be close-Wound or one turn may be spaced from another turn by a distance not substantially greater than the diameter of the wire. However, in a preferred embodiment of the invention, the wire is close-wound,

and the thickness of the copper or aluminum coating is suflicient to provide sufficient copper or aluminum substantially to fill the interstices between the wires after the wrapped drum is heated to a temperature sufficiently high to cause the copper or aluminum to melt and flow.

As shown in Fig. 2, the wires are closely wound on the drum 11 which is preferably precoated with a layer 16 of copper, if a copper-coated steel wire is employed, or with a layer of aluminum, if an aluminum-coated steel wire is employed. It is essential that the thickness of the metal layer 16 and the thickness of the coating on the steel wire be capable of providing suflicient metal to form a bonding metal matrix in which the core of the wire is embedded. In Fig. 2, the relative position of the wire wrapping is shown after fusion. Some of the metal of layer 16 has alloyed itself with the iron base 11, and the 'steelcore 22 of the wire is firmly embedded in the copper or aluminum matrix. In the event that an insuflicient amount of copper, or aluminum, is provided by the coating or layer 16, then a thin copper, or aluminum wire 26 may be simultaneously wound with the coated wire. This additional wire is of a diameter which will substantially fill the space between the coated wires.

As a feature of the present invention, brake flanges of reduced thickness may be used in conjunction with the rows of composite wire turns, the tension of the composite wire being amply sufiicient to reinforce and prevent distortion of the shell flange during use.

The coating surrounding the core should be of sufficient thickness to provide sufficient material to eliminate conductive resistance to the flow of heat where the composite wires are in point or line contact with each other or the brake flange. Preferably, the coating should be sufficiently thick to provide enough material to fill the interstitial spaces, but additional filler stock may be added when indicated by cost considerations Small diameter core wires are preferred because they form smaller interstitial spaces.

From the above, it will be seen that the brake drum or brake discs of the present invention are admirably suitable for heavy-duty heat dissipation purposes. The metal coating of the composite wire is fused and then solidified to form a metallurgical matrix integrally bonding the brake flange and the steel Wire core. At the same time, it affords a highly efiicient pathway for receiving or storing frictional heat developed when a brake shoe is applied to the surface of the brake drum. This matrix forms an excellent transition zone in light weight metal drums which helps to relieve bonding strains in the structure. The brake drum or disc of the present invention is light and sturdy since the brake flange may be relatively thin, yet it is not easily fractured or distorted.

It is to be understood that modified variations may be efiected without departing from the scope of the novel concepts of the present invention.

What is claimed is:

1. A fin-free wire-wound brake drum comprising a ferrous metal flange having an inner surface for contacting a brake shoe, a heat-conductive metal matrix comprising a metal selected from the groupconsisting of copper, aluminum and magnesium metallurgically bonded to and extending uniformly over the entire peripheral exterior surface of said flange, and a plurality of plies of a high-tensile wire selected from the group consisting of steel, high strength alloy steel and molybdenum wrapped about the entire exterior peripheral surface of said flange, each turn of said wire being spaced from an adjacent turn solely by said matrix and metallurgically bonded with and completely encased in said matrix.

2. In a fin-free brake drum comprising a ferrous metal cylindrical flange having one edge thereof integrally formed with a nadial backing plate and the opposite edge thereof integrally formed with a radially and outwardly extending lip, the improvement comprising a plurality of uninterrupted plies of tension-wrapped wire selected from the group consisting of steel, high strength alloy steel and molybdenum wrapped around and extending uniformly over substantially the entire peripheral outer surface of said cylindrical flange from a point adjacent to the backing plate to a point adjacent to the lip, said wire having a coating of a heat-conductive metal selected from the group cosisting of copper, aluminum and magnesium, said plies being disposed with the coating of one turn of wire in contact with the coating of an adjacent turn of wire and wound one upon the other to a height substantially equal to the height of said lip and a matrix formed by the fusion of said coating on said wire metallurgically bonding the individual turns of each of said plies together and to said outer surface of said flange.

3. In a fin-free brake drum including a radially extending portion and a cylindrical flange portion integral with the perimeter of said radially extending portion, said cylindrical flange portion having parallel walls of uniform thickness throughout insuflicient to withstand 6 braking pressure applied to the internal wall surface of said flange, the improvement comprising at least one continuous and uninterrupted ply of wire selected from the group consisting of steel, high strength alloy steel and molybdenum having a coating of a heat-conductive metal selected from the group consisting of copper, aluminum and magnesium, said wire being wrapped with the coating of one turn of the wire of such wrap, in contact .With the coating of an adjacent turn of said Wire and substantially completely covering the entire external peripheral wall surface of said cylindrical flange, the combined thickness of the wire and flange providing suificient metal thickness to withstand the braking pressures to which the internal wall surface is subjected, and a matrix of a heat-conductive metal formed solely by the fusion of said coating on said wire, metallurgically bonding said wire to the external wall surface of said flange, said matrix forming a pathway between said wire for receiving and storing frictional heat developed by brake pressure applied against the internal wall surface of said flange.

References Cited in the file of this patent UNITED STATES PATENTS 1,202,529 Jones Oct. 24, 1916 1,702,391 Price Feb. 19, 1929 1,946,603 Von Wedel Feb. 13, 1934 1,989,211 Norton Jan. 29, 1935 2,109,110 Frank Feb. 22, 1938 2,182,238 Rasmussen Dec. 5, 1939 2,301,235 Willgoos Nov. 10, 1942 2,366,141 Alderfer Dec. 26, 1944 2,371,107 M apes Mar. 6, 1945 2,373,038 Lindsay Apr. 3, 1945 2,476,151 LeJeune July 12, 1949 2,569,612 Laurent Oct. 2, 1951 FOREIGN PATENTS 472,398 Canada Mar. 27, 1951 386,758 Great Britain Jan. 26, 1933

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