USRE3998E - Improved machine for forging or rolling screw-threads upon metal bolts - Google Patents

Description

UNITED STATES? PATENT OFFICE.

JOHN COCHRANE, QF WALL TOWNSHIP, MONMOUTH COUNTY, NEW JERSEY.

IMPROVED MACHINE FOR FORGING 0R ROLLlNGSCREW-THREADS UPON METAL BOLTS.

Specification forming part of Letters Patent No. 63,364, dated April'l, 1867;- antedated March 24, 1867;

` Reissue No. 3,998, dated May 31, 1870.

.To all whom it may concern:

Be it known that I, JOHN CooHaANE, ofthe township of Wall, county of Monmouth, and

`State of New Jersey, have invented a new and`nseful Machine for Forging or Rolling Screw-Threads upon Metal Bolts; and I do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawings, and'to the figures-and letters marked thereon, and in which- Figure 1 is a side elevation of a machine embodying the principles of my invention, and Fig. 2 a front elevation of the operative parts thereof.

The nature of my invention consists in forming or making screw-threads upon metal bolts by means of cross-rolling, the rolls or revolving dies being furnished with projecting threads upon their peripheries corresponding iu reverse to the shape and pitch of thereq'uired screw, yand so inclined or placed relatively to each other that the said projecting threads l shall rake with or conform to the an` glc of such required screw upon the opposite sides of the bolt.

To enable others skilled in the artto make and use my invention, I will proceed to describe the construction and operation of a machine .designed for the special purpose of forming screw-threads upon thescrew-spikes or wood-screw bolts which are used in fastening railroad-rails to the cross-ties, one of the objects of this invention being to cheapen thccost of such fastenings. It is not intended, however, to contine the use of the invention to the manufacture of such screws, as it is applicableto the threading of all kinds of screw-bolts, whether for taking into metal nuts or into timber. w

The said screw-spikes or wood-screw` bolts are usually made of five-eighth or three-quarter inch round bar-iron. The screwedpart is made tapering or of equal diameter for a small portion only of its length, and then taperingdown to a gilnlet-pont. The thread is usually made'thin and of serrated form, so aste enter` freely and hold efficiently 1n timber, and for the sizes stated is about a quarter of an inch in pitch and about an eighth of an inch in depth.

- Forthe production of such a screw I use a pair of rons or revolving dies, about twelve inches diameter, of wroughtiron, faced with steel, and properly tempered, one-half the pe# riphery of such a roll or die being about equal to the length of the helix or thread of such screw as measured on the line of mean surface, and, .preferring the use of cylindrical rolls for this purpose, I make upon the periphery of one of them, A, a series of projecting threadssay three or four-corresponding in reverse to the shape of the threads and spaces' of the required screw. The other roll, B, I make about the same size, but one-half or so of its periphery I` make eccentric and with about a halfinch of throw, the minor radius, a b, of this eccentric part being about a quarter of an inch less than the radius of the roll A, and the major radius, a c,about a quarter of an inch more than the radius of the roll A, so that the eccentric surface a b c shallconform to the taper of the bolt, and it is threaded like the roll A, but the remaining portion of the periphery is without threads.

lf, however, the screwed portion of the bolt is to be of cylindrical form, terminating in a conical or gimlet point, the threaded portion of the roll B must be shaped to suitthese conditions; and if screwsof cylindrical form only are required, the eccentricity of this roll is dispensed with and its threaded portion made cylindrical and of `the same radins as the roll A, but in all cases the denuded portion of the roll B, or of the revolving die corresponding thereto, inust be of such reduced or lower surface as will afford the necessary space in which toinsert the blank bolt between the two while in motion; but if the machine is so operated as to stop on complet ing the screw to give the. necessary interval oftime for inserting the blank, the denuded portion need not be more than about oneinch in length, which would afford agreater portion of the surface to be used as a die, thus enabling the machine to make longer screws with the same diameter of rollor die, or to have such diameter greatly reduced.

rIhe rolls or revolving dies arey attached to substantial spindles, as C and D, and should be securely mounted in proper'bearin gs, as E, F, G, and H, cast upon or attached to a substantial bed-piece, as K K, s as to combine all the parts together, all of which parts should loe-heavy well .tted to prevent yieldiiig' 4or springing .while in operation;

The projecting threads upon 'the rolls or revolving dies instead of being heli cal'lriayl be constructed in the form of annular projections or members placed parallel or in the.

sa'me'direction with each other, land must be adjusted to Ithe a'ngle of the required screw upon the boltsl by inclinin'g'or placing tliero'lls or revolvingdiesin the manner or position necessary for that purpose upon ttheir respective sidesy of `thenhlankforctindwhich,when the threads are upon cylindrical v.urtaaseg is accomplished'by inclining the spindles in opposite directions, as shown at Cjand D in Fig. 1.- Thisfannnlar construction of the screwfo'r'ming threads 'is an important improvement 'not only to t-heoperation o f the machine, but also as effecting :a very great saving in its original cost and subsequent repairs;l 1 e ln settingthe rolls o r revolving dies /curacy'should'be observed in theirajustment,fs`ogas to have thescrew-formi'g threads coaptat'e exactly-in positionfgand angle witli q thethreadsfandspacesof the 'screw to 'be inadenpon the blank or bolt.

. Upon theh'ter vends of `.thev carryingf'sfpin,

dlesforelsewherethereon I attach a pair of pulleys, "L and M', about twehtyffour'inclies (more'or less) in diameter, and of suicient face upon such spindles with the saine speedI and as will cause the bla'nk or bolt to -rotate 1 but if they are driven by cog-wheel'gearing, Y

the ily-wheel should be attached to the pinion or driving-shaft, .but in all .cases when the rolls' or revolving dies are drivenby belts the screwforrning thread-s must be of `the annular construction.-

The'blankor bolt upon which the screw is to be formed, being previously heated, as in the ordinary operations of forging or rolling iron, is lplaced between the 'two`l rollsor revolving dies to the full extent ordistance upon' which the screw is to be formed `upon it, the head of the bolt being to the outside rfront. There is also a support, as shown by dotted lines at il? in 'bothlignes, upon which .the heated bolt is deposited when placed in .the machine, and upon which it rests till 'the threaded portion of 'the roll B or revolving diecorrespondingtherctocomesin contact with as indicated by the arrow h in Fig.

n, whmt winne pressed-against thev m11 Ln or oppositerevolving die, The threadson both rolls or revolving dies willthen penetrate the blank orbolt-on its opposite sides, and one 0f therolls or revolving dies, actin g across the sur-l face of the bolt from below upward and the lother in like manner acting across the surface from above downward, and the screw-formin g threads penetrating the blank or bolt to their full depth, and, as itY were, gearing into its 'surface onitsfopposte sides andewith oppo` site directions of motion, itis thereby causedto revolve upon its own' axis between them, v 2, and making the indentation caused by the penetra-` tion ofthe threads on the rolls or 4revolving -dies continuous upon the boltby their angu lar action, thus forming an elevated helix or screW-th'readupon itbetween the said indentations, andthe bolt being in thisymanner rotated uponitsown axis-from right lto left,-

itwill beworked outward to the front by the action ofthe screw-forming threads upon it asfthe `operation of making the screw progreses,in which screw-forming threads the bolt is moved longitudinally, as in the threads 'of "a hut, till the Vscrew is completed or l'nished from the-,neckto the point, when it is thrownout in front from between the rolls or .revolving dies, as shown at N in Fig. 1.

I.n "thus forming 'a 4screw upon a blank or v bolt the kmetal which has been forced from between th'e threads is worked into the substance ofuthe bolt, thereby adding to its length and thus utilizing all the material, l'and the opera-vtion has the hirther etfect of consolidating the "lnetal in the central part of the bolt, which makes. the Vbolts that lare threaded by thisprocess much stron'ger than thosescrewed in the usual manner by cutting-dieser chasing, for,

'as is well known, the central portion of round bar-iron is of inferior strength Vwhen'compared with the exterior portion of such iron, yet in making screws by cutting away the metal from betweenthe threads it is the` best and strongest portion of the iron that is `removed from the bolt and wasted, and the threads which are formed by cutting-dies or chasing, being across the fiber of the iron, are of less streng-th than those which are formed by crossrolling, because by this mode of production the Yfiber of the iron is retained.

The speed of the rolls or revolving dies lshould be so regulated as to suit the dexterity of the attendant in placing the blank bolts between them at the proper moment, so that a'blank bolt may be placed between the rolls or revolving dies, have a screw'formed upon lit, and be delivered from the machine at each revolution. A machine thus constructed and operated could turn out from thirty tosixty of these screwspikes per mirute,'as the blanks may be deposited, when taken from theheating-furnace, in proper order near the support P, so .as tofbe easily set orpushed into the space between the' rolls or revolving dies at the :proper moment. 'It would therefore be possible for lsuch a machine to make and deliver from twelve thousand to twenty-five thousand or moreof such screws per day. v 4 Y l have said that the rolls or revolving dies, instead of being driven by belts, may be driven by cog-wheel gearing, so as to unite and combine their movements. When thus driven, both rolls or revolving diesmay bemade with a threaded and a plain part, as shown in the roll B, for the cog-wheel gearing will insureK the -return to each other of such threaded and denuded parts in each revolution, while the possibility of the belts slipping on the pulleys requires that one of the rolls or revolving dies, when operated by belts, should be completely threaded, so as to be always in position to oppose the threaded portion 'of theother roll or revolving die; but instead of making either or both the rolls with threadedV and denuded parts in their peripheries, as described, both of them may be cylindrical and `havecomplete threads upon their peripheries, like the roll A, by causing either or both of said rolls to move laterally to and from the other at proper intervals by means of cams or other suitable mechanism, as well known and understood by the constructors of such machinery, so as to open the rolls wide enough apart to receive the blank between them without being acted on by them, and then to close them upon it so as to form a screw thereon by the penetration into such blank'of the members or threads that are on the peripheries of the rolls.

In this mode of construction the diameter of the rolls is not controlled by the length of the helix to be formed upon the bolt. rEhey may therefore be of any convenient diameter, and by giving such form to the camlor such movement to the laterally-operating mechanism as may be required screws ot uniform diameter or tapering or gimlet-pointed may be produced, andvarious other modifications or arrangements ofthe mechanism might possibly be suggested or made without there- 4by'changing the nature of the invention. I`

do not ltherefore limit myself lto any specific arrangement or proportion of the parts or `mode of operating the same, but claim the right to construct and'operate the machine in the manner best calculated to answer the purpose for which it is intended so long as the principles by whichthe invention is characterized are employed.

The bolts passing through this machine being highly heated, it will be necessary'to cool all the parts with which they come in contact, so as to preserve the machine from the injurious etects ofl such heat, which cooling may be done by the application of water thereto, as is usual in' such cases.

Having thus described the fnature, construction, and mode-of operating mechanism for making screw-threads on metal bolts by means of cross-rollin g, and described some of the variations in construction and operation of which such cross-rolling mechanism. is susceptible, what I claim therein "as my own invention, andv desire to secure by Letters Patent of the United States, is

1. 'llhe combination, with each other, of two rolls or revolving dies having on their peripheries projecting threads of proper form and arrangement to produce or make the required screw upon the heated blank, and having a denuded portion ot' lower surface in either or both of said rolls or revolvingr dies so as to permit the introduction of the blank bolts between them at the proper moment for that purpose in each revolution, substantially as herein described.

2. The combination,with each other, of two rolls or revolving dies having screw-forming threads on their pcripheries, so arranged, con' structed, and operated as to produce or make screws upon metal blanks or'bolts of uniform diameter or tapering or gimlet-pointed, substantially as described.

3. The combination, with each other, of two rolls or revolving dies having annular threads or-portions thereof for making screws upon metal blanks or bolts, and so inclined or placed, respectively, as to conform to the angle of such screw upon its opposite sides, and so operated as to make screws upon'metal blanks or bolts of uniform diameter or tapering or gimlet-pointed, substantially as described.

4. The bolt-threading device consisting of two rolls or revolving diesr with annular threads arranged in relation to each other so that said annular threads shall conform to the rake of the required screw, substantially as described.

JOHN COOHRANE.

Witnesses:

A. B. MALooMsoN, Jr., J. H. HUNTER.

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