US1393886A - Machine element - Google Patents

Description

W. G. DOTY.

MACHINE ELEMENT.

Patented 001;. 18, 1921.

SHEE SHE 1 W. G. DOTY. MACHINE ELEMENT. APPLICATION FILED JUNE 25, I917.

Patented Oct. 18, 1921.

2 SHEETSSHEET 2.

citizen of the fication.

Application filed June 25,

To all whom it may concern:

Be it. known that I, WALTER G. DOTY, a

United States, residing at ayton, in the county of Montgomery and State of Ohio, have invented certain new and useful Improvements in Machine Elements, of which the following is a specigear wheels and process or method of producing finished cast metal gears, cams, slides, blocks, and other machine elements, without the necessity of machine operations. .The object of the invention is to improve the structure of cast metal .gears and other machine elements as well as the means and mode of producing both internal and external gear wheels, whereby they will not only be cheapened in construction, but will e more eflicient in use, more durable and uniform in operation, economical in manufacture, and unlikely to get out of repair.

furt er object of the invention is to provide means for accurately forming the teeth of such gear wheels and 'afi'ording smoothly finished working surfaces upon gears, cams, slides, and other machine elements, without the'necessity of cutting or finishing such teeth or working surfaces by machine operations- A further object ofthe invention is to" provide means for reinforcing cast metal gears, cams, slides, and other machine elements, whereby they will have a-less tendency to breakage hile in use and whereby in the event of breakage the parts will be he d to ether temporarily, thus reducing danger roin flying pieces. A furtherobject of the invention is'to provide a gear in which the vibrations will be materially dampened thereby rendering the gear less noisy. A further and important object of the invention is to improve the method or proc- Myinvention relates to particularly to a 'ess' of manufacturing cast metal gears as hereinafter described. With the above primary andv other incidental objects in vie as will-more fully appear in the specification, the sists of the parts and combinations thereof and the procof production and operation, or their equivalents, as hereinafter described and were t e Specification of Letters Patent.

-8 and 9. Fig. 11

vention conf construction, the f Patented-Oct. 18, 1921. 1917. Serial No. 176,870.

Referring to the drawings, Figure 1 is a side elevation of the formingtools for corrugatiug the peripheral rim or facing strip. Fig. 2 is a side elevation of the finished ar. Figs. 3 and 4 are detail views of tooth orms of the peripheral rim. Fig. 5 is a de-v tail sectional view of the completed gear h the several strata be' g enlarged or. exaggerated. Fig. 6 is a SGCtiOllfllVlGW of the sand mold for the gear, with the peripheral corrugatedreinforcement and facing strip or rim positioned therein. and the master'form or ring inclosing the: corrugated Fig, is a. top plan with therein. Fig. 8 is a similar viewof a sand mold embodying a modification of the roca ess or method o producing the gear. 9

of the sand mold for producing the gears in accordance with the process illustrated detail sectional view of a gear, the result of the process illustrated in Figs. is a plan view of a modification of the master'form.

f ike parts are indicated by similar characters of reference throyghout the several views.

The present method of manufacturingmachine elements as particularly applied to the production of gears involves the use of an initial blank of either steel or cast metal in which the teeth are milled or cut by means of a suitable miller or hobb. A steel blank affords gears for high duty or high efliciency where great durability, accuracy and wearing quahties are required, whereas for gears requiring less accuracy and wearing quality, the gears are cut from cast iron. or other cast metal blanks. In some instances, gears have been cast with integral teeth, but the expansion and contraction of the metal while in the mold tends to distort e gears and results in misshaped and irregularteeth. Such cast gears necessitate additional machine operations to afford fin ished working surfaces upon the teeth.

The present invention is designed to a ford commercial gears which may be cast 1n sand or other molds, the teeth of whlch will be formed sufiiciently smooth and accurate in such molds asto obviate the necessity i9! l aohine operations. The smQQih 111 force the body 2 rable wearing surface afforded upon the faces and flanks of the gear teeth is greater than that produced by the ordinary cast iron or other cast metal gear methods.

The finished product illustrated in Fig. 2 comprises a corrugated peripheral rim 1 preferably of steel ronze or other suitable material or metal which incloses a body 2 of cast iron or other cast metal. The body 2 conforms to the interior of the corrugated peripheral rim, whereby the corrugations of said rim fo'rm reinforcement faces for the gear teeth. Interposed between the rim 1 and main body 2 is'a film or stratum 3 of softer material, such as tin which serves to dampen the rattle or clatter of intermeshing gears.

Not only do the corrugations of the peripheral rim form a more smooth and better wearing surface for the. gear teeth than that. afforded by the cast metal of which the body 2 1s composed, but it. also serves to reinagainst breakage or cracking. In the event that the body 2 is cracked it holds the several pieces in close union,

- thereby preventing accidents and injury to after mentioned, the

the machine or to the operator.

The corrugated peripheral facing rim 1 may be formed in any suitable manner such as by passing a strip of the desired material between a succession of forming rolls, or by a succession of forming operations intermediate substantially straight dies and suitable coacting punches. In Fi 1 there has been shown a" method in whic the strip of material to be operated upon, indicated at 1, is passed intermediate two forming memhere 4 and 5, each provided with suitable gear teeth intermeshing with one another. These teeth are adapted to initially or roughly form the corrugations in the strip 1*.

To produce the desired effect, the teeth 6. of the forming roll 4 are of less dimensions than the desired teeth to be produced upon the finished gear. Having determined the size and pitch of the finished gear product, the master form 4 is cut or machined from a suitable blank in the usual manner. As shown in the drawing, the teeth of the formin member 5 are of normal dimensions, while the teeth of the forming roller 4 are of less than normal dimensions, being equivalent to the normaltooth less the thickness of the strip 1* tire periphery of thetooth. Thus when the strip 1 is accurately formed aboutthe teeth 6 by action of the forming punch hereinteeth 6 plus the strip extending thereabout becomes substantially equivalent to a normal tooth.

Intermeshing teeth of the shape shown in Fig. lwill not form the strip '1 accurately to the contour of the tooth. The strip will be only roughly shaped or corrugated by the rolling or intermeshlng action of the teeth but which may be of,

acted upon about the enof the forming members 4 and 5. However, there is provided a reciprocatory forming member or punch 7 coacting with the toothed member 4. The toothed forming member 4 is advanced intermittently or through a step by step movement by any suitable mechanism and during the intervening intervals of rest, the reciprocatory forming tool or punch 7 is brought into engagement with each succeeding tooth thereby closely setting the initially or roughly corrugated strip 1 into close conformity with the tooth 6 of the forming As thus set or conformed upon t e tooth 6 the exterior line of the corrugation will conform with the outline of the desired tooth to be produced upon the finished product. The finished corrugated strip 1 may be formed of any desired length and pieces may be subsequently cut therefrom of sufficient length to form the gear rims of desired dimenslons. If these corrugated or finished strips are to be used only in the production of gears of a size equal forming member, 4, little or no distortion would occur in bending the corrugated strip into annular form preparatory to castlng the gear body 2 therein. However, to obviate any distortion of the tooth forms n bending .the corrugated strip the said strip may be weakened intermediate the roots of succeedin teeth as indicated at 8, Fig. 3. This is e ected by providing a slight rib or bead 9 upon the forming member 4 lntermediate the teeth 6 upon which the strip is forcibly driven' by the action of the forming tool or punch 7. There is thus formed in the inner side of the strip an as indicated at 8. The corrugated strip being thus weakened at points intermediate the succeeding tooth forms upon the subsequent bending of the strip will yield at these the tooth roots of the succeeding tooth forms.

roller 4.

illustrated at indentation,

produced by correspondingly shaping the opposing faces of the forming member 7 and the forming member 4. I

Such weakening or indentations in the strip are especially desirable when the tooth forms are produced in straight dies by ordinary punch and die methods or when produced upon rotary forming members differing in diameter from that of the finished as the case may shown in Fig. 11 venient and economical in the production product. It will In either event the degree of he subsequent bending of distortion due the corru ated and he corrugated peripheral strip being thus formed by any suitable method whereby tooth shapes properly spaced and proportioned-are produced, sections of said corrim. In lieu'thereof such coating or film may be deposited by any of I the well known electroplatlng methods.

rality of circular openings will be found more conof small gear pinions.

r having been positioned within the master form or ring 11 with the points or crowns of the teeth in contact with the inbe, and having thereon in properly spaced relation relief configurations corresponding to the hub boss and marginal flange ofthe gear, This pattern be obvious, however, that is rammed up in the flask filled with sand to produce the usual intaligo form in the sand. The master form 11 with the inclosed'corrugated gear rim 1 with the spaces intermediate the cast within the corrugated periph- 1. by pouring molten metal within the mold. 1

Molten metal and in molten state, possesses the peculiar charwlthin the tooth forms of the rim producing tooth bodies of increased density. This effect is not attainable in ordimethods where the metallic to chill the than the body of the gear; The contact of the molten metal with the metallic film or coating of he inner sideof the corrugated rim, fuses the metallic coating and serves to firmly unite the rim with the central of different physical characteristics which not only serves as a union between the rim and the central body 2 but also serves as a dampening element to interrupt the vibratory motion of the gear when in use and thereby deaden the clatter and rattle of intermeshing gears rendering them less noisy in operation. The contraction of the cen.-

the master form or ring 11.

In Figs; 8 and 9 there is illustrated a modification of the process heretofore described in which the or ring 11 is dispensed with and in which therefore i The external master form f v 65 erably left open an internal annular form or retaining member 16 of sheet metal is employed in lieu of the external master form or ring 11. This internal ann lar form 16 serves to retain the true circular form of the corrugated rim which is compressed into contact with the internal form 16 by inclosing helical spring coils 17 which tend to contract upon the periphery of the corrugated rim 1. In operating this modified method the internal annular form 16 and the inclosing helical coils 17 together with the corrugated rim 1 are preferably assembled in their relative positions prior to the tinning or metal coating operation as hereinbefore described. While this coating or deposit of a metal film upon the corrugated rim has been termed tinning it is to beunderstood that it is not limited to the application of metallic tin alone, but other metals or substances may be employed in lieu of tin.

The annular support or form 16 and the inclosing coils 17 are preferably, though not necessarily, temporarily secured either by soldering, brazing, electric welding, or are attached without direct engagement, by wiring them to the rim.

Like the preceding described method, a pattern is employed for forming in the sand of the mold an intaligo design equal in diameter to the external diameter of the inclosing coils 17 and having thereon surface configurations corresponding to the hub boss and marginal flangesof the gear. The rim 1 with the assembled support or annular form 16 and inclosing coils 17 are deposited in the intaligo design or pattern formed in the sand mold and molten metal is poured within the mold as before described. This molten metal flows over and around the annular reinforcement or supporting member 16, inclosing said annular member 16 and therewith and with the inthe corrugated peripheral rim 1 of the gear. The result is the formation of an integral body of which the corrugated peripheral rim 1 forms an external stratum.

Intermediate this external stratum or rim and the central gear body is an interposed stratum of metal of diflc'erent physical characteristics which as before mentioned serves as a dampening element to deaden the rattle or sound of the gears. This same dampen ing stratum will extend also about the annular support or form member 16. This form member 16'is permanently embedded in the body 20f the gear where it forms an additional reinforcement member serving to distribute the unequal strains to which the gear is subjected and preventing the disintegration and breakage of the gear. In this mode of procedure, the intervening spaces between the succeeding teeth may if desired be. filled or packed with sand, but are prefto provide intervening air chambers which. serve to chill or cool the metal forming the bodies of the teeth. The encircling coils 17 about the rim being preferably firmly attached to severalof the tooth corrugations and being in contact with the corrugated rim only at the points of the teeth, does not readily absorb the heat from the molten masswithin the corrugated rim and therefore tends to resist the expansion of the mass as before described. By the time that the encircling coils 17 have absorbed sufficient heat to materially expand them, the body of metal within the. tooth corrugations of the rim has cooled sufiiciently-to have passed beyond its expansive state and the only result of the heating of the encircling coil 17 is to separate the coils from the corrugated rim at their points of attachment, whereby said coils and the gear rim which is now an integral part of the cast gear will fall apart upon their removal from the sand mold. The coils 17 serve to hold the corrugated rim in close contact with the form or support 16, thereby insuring a perfect circular formation of the rim. The resulting gear will be similar to that produced by the first described method. Such gear will possess smooth uniform teeth and will be capable of being placed in operation without the necessity of special machining or finishing operations. Such gears .will possess unusual tensile strength and inasmuch as their vibration is interrupted or deadened by the embodied zone or stratum of characteristically different materiah they will be found less noisy in operation. ile for illustrative purpose the invention has been particularly described in its application to the production of gears, it is to be understood that it is not so limited but may be utilized for other machine elements such as internal and external cams,.slides, bearing blocks, or other parts which it may be desired to provide with either a smooth surface, a finished face, or a reinforcement as herein set forth.

It is to be understood that the term gear as it appears throughout the descriptionand claims is not limited to spur gears an pinions but is to be interpreted as including internal gears, 'bevel or miter gears, gear racks, segmental and other gear elements. While cast iron is the material usually employed at this time for the main or support? ing body, other metals or alloys may be used as may also other rigid non-elastic or nonyielding materials such as phenolic condensation products or self-hardening materials capable of .being molded.

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of a vantage before enumerated as desirable but which obviously is susceptible of modification in its form,

, proportion, detail construction or arrangement of parts, Without departing from the principle involved or sacrificing any of its advantages.

While in order -to comply With the statutes, the invention has been described in language more or less specific as to certain structural features, it is to be understood that the invention is not limited to any specific details, but that the means and construction herein described comprise but one mode of putting the invention into effect, and the invention is therefore claimed broadly in any of its possible forms ,or modifications Within the scope of the appended claims.

Having thus described my invention, I claim 1. As an article of manufacture, a gear comprising a cast metal body, sheet metal rims for the teeth and an interposed stratum of metal of different physical characteristic, said cast metal body, sheet metal rim and interposed stratum of different metal being integrally united into a conjoint body.

A machine element comprising a fluted strip constituting a succession of tooth forms, said strip being weakened at points intermediate successive tooth forms and flexed into an outline shape of the finished product, such flexing occurring at such Weakened points Without material distortion of the tooth forms, and a supporting body inclosed within such flexed strip.

3. As an article of manufacture, a gear comprising a cast metal body, a continuous sheet metal tooth rim and an interposed stratum of soft metal all united into a conjoint body, substantially as specified.

In testimony whereof, I have hereunto set my hand this 2nd day of June, A. D. 1917.

"WALTER G. DOTY.

Witnesses MARVEL HOAGLAND, F. L ALKER.

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