US1494409A - Method of producing copper trolley wheels - Google Patents

Description

I W'S-B"DL E WWW? May 20, 1924.

w. s. BIDLE METHOD OF PRODUCING COPPER TROLLEY WHEELS Filed Feb. 27 1922 raaaae May an, 192.

WILLIAM S. BIDLE, F CLEVELAND, OHIO, ASSIGNOR TO THE COPPER PRODUCTS FORG- ENG COMPANY, OF CLEVELAND,

OHIO, A CORPORATION OFDHIO.

METHOD OF PRODUCING COPPER TROLLEY WHEELS.

Application filed February 27, 1922. Serial No. %,df58.

Toall whom it may concern:

Be it known thatv 1, WILLIAM S. BIDLE, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and 5 State of Ohio, have invented certainnew and useful Improvements in a Method of Producing Copper Trolley Wheels, of which the following is a specification.

This invention pertains to a method of making trolley wheels of high electrical conductivity land of the requisite hardness to withstand persistent wear and usage, and t-he steps taken make it possible to producetrol- .ley wheels of pure'or unalloyed copper having relatively hard wearing surfaces capable of giving long service and the maximum electrical conductivity.

The trolley Wheels in general use are made of brass, an alloy consisting essentially of copper and zinc. The addition of zinc to copper very materially lowers the electrical conductivity, and as commonly practiced, the making of a trolley wheel of brass of the requisite hardness and composition involves both casting and machining operations. The cost of casting is materially increased because the groove in the wheel requires cores t6 be used in the molding 0peration; such castings frequently have imperfections and blow holes; and in machining the groove such imperfections and holes are liable to appear in the final surface and require the imperfect product to be discarded at a considerable loss. The presence of blow holes or imperfections below the inthat these imperfections cause trouble as soon as. the surface wears down to that point, and the presence of metals of lower conductivity than copper is objectionable in a trolley wheel because such metals cause arcing and pitting in the wheel.

My general object is to forge and cold roll or cold work a cast piece or hot rolled or extruded bar of unalloyed copper to produce a trolley wheel without blow-holes or imperfections and with hardened surfaces esecially at the wearing places in the wheel.

11 speaking of hardening the copper surfaces, I mean such hardening as takes place in cold working operations as exemplified in cold drawn wire and cold rolled shegs of cop er, and the hardness of the 51 ved sur ace of a copper wheel as produce by my method is preferably approximately the final machined-surface is also objectionable formly hardened wearing'surface.

Now referring to the annexed drawing, Figs. 1 to 8, inclusive,.are diagrams illus- 7 trating the various steps taken in producing a trolley wheel according to my invention. Figs. 9 and 10 are side and sectional Views of afinished trolley wheel, and Fig. 11 is a side view of a wheel and swaging die to illustrate a swaging operation.

In practicing the invention, a short round cylinder or other shaped piece 2 of metal -(see Fig. 1) is either cast in this form or cut to a given length from a long bar which may in its making be either cast, extruded, hot rolled or cold drawn. Preferably this stock is pure or unalloyed copper, but the method need not be confined to the working of copper but may be practiced with other metals capable of being worked hot and cold in substantially the same way. In this connection it should b understood that only a narrow range of brass compositions can be hot worked under the action of pressure, to but such compositions produce inferior trolley Wheels; and where brass or any similar composition is used and cold worked it is generally necessary to anneal the worked stock frequently, which again changes the properties sought for in the final product.v Therefore pure or unalloyed. copper is preferred, and assuming the blank 2 to be of such unalloyed copper, it is placed between a pair of dies adapted to produce a diskshaped body 3 having hollow hubs or en largements 4-4 on opposite sides thereof and a series of radial ribs 5 on one or both sides, see Fig. 2. These ribs 5 are shown plainly inv the finished wheel, Fig. 9, and 3% their main function is to interlock with the rotary drivin holder or die during grooving and rolling operations as hereinafter described.

Now, returning to Fig. 2, the die-pressing E359 operation leaves a parting flash at the periphery of hody 3 which is trimmed oil; and body 3 is relatively thicker near the hub than at the periphery, being given a substantially tapering form in cross section. The pressing operation is also performed 'on a blank 2 heated to a cherry redto avoid brittleness in 'the pressed stock and subsequent annealing and to relieve the pressure on the dies.

The next step in operations consists in placing the pressed body 3 between another pair of dies constructed to permit the disk to he distended to a larger diameter while tapering and reducing it in thickness in its outer circumferential portion and rounding it convexedly on opposite sides to produce a round annular swell or enlargement 6 at the base of the tapering portion 7, see Fig. 3. Both hubs, H, are also compressed to a shorter length in this operation, which is a cold pressing step to impart a definite hardness to the co per by flowing the metal upon itself, especially at the ends of hubs 4 where exposed to wear when in use in a trolley harp having frictional or spring-engaging contacts for conducting the electric current from the wheel to the harp and pole. In connection with Figs..2 and 3, it should be noted that the outer ends of the hubs in Fig. 2 are relatively thin and tapered and that there is an offset 8 internally to confine the area of movement of the metal under cold working to the outer end portion of the hubs, thereby largely confining the hardness in the metal at the wearing places where most needed.

The pressed product of Fig. 3 can be made directly from blank 2 by a single hotpressing o eration, omitting the preceding step and b ank of Fi 2, but, I prefer a sequence of hot and cofil pressing ste s as described to derive the benefit of the ardness imparted to the hub-ends and to theouter tapering portion 7.

The next step involves a splitting or parting of the pressed disk, and the parting takes place on the median-line of the disk begin ning at the periphery under greater orv less pressure dependent upon the type of parting tool employed. As shown in this application parting is effected initially by the cutting ill) action of a sharp edged parting tool such as a reversely beveled cutter or roller 9. In this proceeding the disk-shaped body 3 is held securely between a pair of clamping holders or dies 10 having opposed faces of conical form and central sockets to receive the hubs 4 and .constructed to interlock with ribs 5 so that the clamping holders and the work may be jointly rotated at a speed of approximately 200 'to 300 revolutionsper minute and the work solidly seated against the heav; pressure brought to hear against it by parting roller 9 whlch is fed forward by a screw or any other suitable-means not shown.

As the parting roller 9- enters the work the stock at each side of the median line spreads butwardly and curls away from the tool on curved lines until the desired depth of parting is reached, substantially as shown in Fig. 5, wherein dotted line a indicates the depth of entrance of the cutter or roller. This operation starts the formation of a groove in the wheel body 3 and is important in that the disk is divided without waste or loss of material and in that the cold rolling of the material toward the axis and bendin of the material sidewise acts to harden the copper and to make a hardened finish for the groove in the wheel.

In lieu of parting the stock as described, I may usea somewhat thicker disk blank and cut a circumferential groove within its periphery, but this has the disadvantage of wasting material, it is a very difiicult opera; tionin colpper, the base of the slot developes improper y for .efi'ective future'working, and the material in the sides does not flow or roll upon itself to efiect hardening.

In artin the material with a sharp tool or rol er 9 t e bottom of the groove or channel is of acute V-shape and there is a tendency in the metal to split or crack beyond the sharp edge of the roller. Whether this split or crack actually occurs or not if further spreading and shaping operations are performed on the diverging sides from within the tendency is to produce a seam or crack in the body on the parting line and to break ofl the side flanges before they can be shaped or expanded to their proper width. Therefore, the next step consists in feeding a narrow cutting tool 10 with a round vcutting edge into the bottom of the V-shaped'groove to remove a portion of the stock, the work rotating until the desired depth of cut is obtained substantially as indicated by the dotted line b in Fig. 6. As a result any crack or seam at the parting line is obliterated and a round bottomed groove or slot 11 is produced therein which greatly facilitates the subsequent bending and shaping of the side flanges12 on straight diverging lines without splitting the body or causing the flanges to "crack or break away at their base. Briefly, cutting a round slot at the finish of parting operations involving the use of shar tool removes any fractures or cracks and eaves the central body of metal intact, and the stock at each side of this round groove is also made thinner to facilitate bending of theside flangcs. The reason for producing the annular convex enlargements at each side of bed 3 also now becomes a parent as without t is extra stock and roun ed outline it would be difiicult to cut the circular base slot without sacrificing stren h and still ermit thedevelo ment of a re atively wi e flaring groove in the wheel and cold workin of the side race,

Such cold working proceeds when theslot cuttlng o oration is finished, and consists in either ro mg or swaging the parted wheelscleroscopic hardness approaching or equal to the hardness of trolley wires in general use. vTo exemplify the rolling operation I show in'Fig. 7 a heavy roller 14: having flat converging working surfaces 15 terminating' in a round edge 16 of slightly larger the round slot 11 in the when this 'roller is fed under pressure between the flanges while the work is revolving the curved inner sides of'the flanges are rolled and worked substantially flat until finally the round edge 16 of the roller enters the round groove and cold works the sides thereof in the same way.

diameter than wheel body and This operation may be repeated with a slightly larger roller, and carried to completion with still another roller 17, or the the base of the groove and though actualtendency to elongate flanges.

last roller may be used immediately following the use of roller 14, whichis broader and posswses difierent angular working surfaces and a larger rounded edge 18 than roller 14 to. spread the flanges of the wheel to a greater degree the groove in and to enlarge the radius of the wheel. In spreading and cold working the flanges the pressure which is applied moves toward the axis of the wheel, and the material involved in the surface of the grooved area is gradually rolled or caused to fiow upon itself toward there is a slight the side doing the outer or peripheral edges of the flanges are engage by curved shoulders 19 at each side of roller 17 and also rolled and cold-worked which In so hardens these edges. This last result is im-.

portant because this portion of a trolley wheel frequently strikes or meets with ohstructions and if too soft, would become marred or dented. In the final cold work ing operation the side flanges are pressed fiat against the sloping faces of the holding dies 10 and the flange edges are confined on all sides. This trolley wheel which now possesses a permanent change in form and a uniformly hard surface in its grooved area where the wheel is adapted to bear against a trolley wire and at its huh ends where the outer faces are adapted-to engage the current conduetingcontacts used in the trolley harps "in actual. serri ce.

However, toaetually complete a copper wheel it is desiahle to provide a hardened a round opening ll@ practically completes the and reamed through the hub of the wheel.

"A completed wheel with such a bushing is shown in Figs. 9 and 10. This bushing may be provided with grooves to hold graphite or other lubricant, but as this is a common article shown in Fig. 6, and to illustrate this conception I show in Fig. 11 a tapered Y swaging die 21 entered within a partly finished wheel such as shown in Figs. 7 and 8.

In swaging, the die is forced into the groove between the flanges at timed intervals while the wheel and its clamping holders are at rest, and is withdrawn and held out of action while the wheel is revolved part way to permit the operation to be repeated in an adjacent sector in the wheel. These swaging steps may proceed successively in different radial portions of the wheel with one set of dies until, the wheel is given one complete revolution, and then similar ste'p by step swaging operations may be repeated with one or more larger dies to produce the finished article shown in Figs. 9 and 10. If desired, swaging androlling o erations may proceedalternately, and the nal operation may involve the use of a roller to-work the surface material in the grooved area downwardly at each side into the base of the groove on a line moving spirally toward the axis of the wheel, thereby producing a permanent change in -form and property of the metal resulting in a hard smoothly finished surface capable of resisting persistent wear and usage. In forming the groove the sides of the groove in the finished wheel will eventually conform to the beveled sides of the roller but there is a definite 'limit of movement of the roller into the wheel. This limit is determined by the bottom of the groove and by the difference in speed of rotation at the pressure applying apex of the roller as compared with the beveled sides thereof. In other words. in" applyingpressure beyond a certain point the bite at the apex of the roller tends to dilacerate and peg the surface of the metal, and the sides w1 ferential speeds.

What I claim is:

1. A. method of making trolley wheels.

eonsisting in forming an annular groove slip where engaged and moving at diliin a body of ductile and tenacious metal 7 working the-material in the flanges whilethe parted blank is revolving.

4. A method of making a grooved wheel, consisting in parting a disk-shaped metal blank annularly at its periphery; in removing a portion of the stock at the. base of the partin and in spreading and'shaping the parte sides.

5. A method of making a grooved metal wheel, consisting in clamping a metal disk upon a rotatable member and rotating said parts; in forcing abeveled tool into the peripheral edge of said diska predetermined distance until the opposite sides of the disk curve outwardly; in rounding the metal at the base of the parting in the disk; and in forcing the material involved in the parted surfaces to flow under. the action of great pressure moving inwardly from the periphcry to the rounded base.

6. A methodof making trolley wheels composed of ductile and tenacious metal of high electrical conductivity,v consisting incompressing a body of the desired material between dies into the form of a disk; in

parting the disk circumferentially under the action of pressure until an annular groove is formed; and finally iniworking' the material in the area of the groove under the action of pressure moving inwardly toward the base of the groove.

7. A method of making trolley wheels composed of ductile and tenacious metal of high electrical conductivity, consisting in subjecting a blank of the desired material to the action of pressure moving to flow the material upon itself externally of the blank; and in forming a relatively deep circumferential groove in the edge of the blank under 'the action of pressure moving to flow the material upon itself in the area of the groove.

8. A method of making trolley wheels composed of ductile and tenacious metal of high electrical conductivity, consisting in first forming a disk-shaped blank of the desired material; then in subjecting said blank to the action of pressure adapted to aaeaaoe distend the blank! circumferentiall and compact its central portion; and t en in grooving the blank circumferentially to a predetermined depth under a moving pressure capable of producing a permanent change of form and property in the metal involved in the grooved area.

9. A method of making trolley wheels, consisting in crowding an annular groove to a substantial depth in the periphery of a disk composed of unallo ed copper until outwardly curving side anges are produced, and subse uently pressing said flanges outwardly on dliferent lines and hardening the grooved area.

10. A method of making trolley wheels composed of ductile and tenacious metal of high electricalconductivity, consisting first. in shaping'a blank of the desired material into a disk having central enlargements; secondly; in subjecting said disk to the action of pressure to flow the metal upon itself in its central and circumferential portions; thirdly, in producing an annular groove in the circumferential portion of the disk under the action of pressure moving in wardly toward the axis; and fourthly, in subjecting the grooved area of the disk to the action of pressure moving to effect a permanent change in form and property of the material in said area.

11. A method of making trolley wheels composed of copper or an alloy having substantially the same properties as copper, consisting in shaping a body of the desired metal into a disk having laterally extending enlargements at its center and of tapering thickness in its circumferential portion,

and in parting and spreading the circumferential portion of the disk to produce an annular groove and flaring side flanges under the action of pressure moving inwardly from the peripheral edge of the disk toward the axis of the central enlargements.

12. A method of making trolley Wheels composed of a ductile and tenacious metal of high electrical conductivity, consisting in forming a body of the desired metal into a disk-shaped blank at a high temperature; in compressing and reshaping the said blank at a relatively lower temperature; and in grooving and working the material involved in the circumferential portion of the disk under a cold rollin pressure.

In testimony w ereof I aflix my signature to this specification.

WILLIAM S. BIDLE.

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