US925661A - Composite stock for machine-knives and method of making the same. - Google Patents

Description

F. SEARLE.

COMPOSITE STOCK FOR MACHINE KNIVES AND METHOD OF MAKING THE SAME. APPLICATION FILED MAY 7,1908.

v9295, 661 Patented June 22, 1909.

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- Z/L/iZ 2125525- UNrTED STATES PATENT oFFIoE.

FREDERICK SEARIiE, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO COES WRENCH COMPANY, WORCESTER, MASSACHUSETTS, A CORPORATION OF-MASSACHUSETTS.

COMPOSITE STOCK FOR'MACHINE-KNIVES AND METHOD QF I VEAKING- THE SAME.

Specification of Letters Patent. 7' Patented June 22, 1909.

Application filed May 7, 1908. Serial No. 431,331.

T all whom it may concern:

Be it known that I, FREDERICK SEARLE, a citizen of. the United States, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Composite Stock for Machine- Knives and Method of Making the Same, of which the following is a specification, reference being made therein to the accompanying drawings.

The object of my present invention is the production. of a securely welded composite stock for machine knives of the double edged channel-bar pattern, more especially for the ledger knives for lawn mowers, or similar knives having two turnedup edges. Also, to provide a conveniently workable process whereby a double edged channel-bar knifestock can be successfully and economically manufactured, and the steel edging material efficiently affixed to the body or backing a'V-welded integration; and to practically produce a composite stock of such character that the dual cutting-edges of knives made therefrom can be properly hardened and tempered without destroying the capacity of the product for beingstraightened or fitted after the knife is formed, or while being formed therefrom; thereby afiording more perfect and stronger knives of the pattern s ecified than heretofore produced. These 0 jects I attain by the means hereinafter explained, and illustrated in the drawings,wherein Figure 1 represents a cross section of the iron and steel members as primarily assembled in the fagot. Fig. 2-re resents across section of the billet after going through the first reduction pass. Figs. 3 and 4 represent successive cross section shapes of the composite bar after going through the second and third reduction passes respectively. Fig. 5 represents a cross section of the completed stock as it is issued from'the final pass of the reduction rolls; and Fig. 6 is a front view of a pair of reducing rolls having passes formed for producing composite knife-stock in accordance with my invention.

In a machine knife of the channel-bar shape it is desirable that the upturned lips, whereon the cutting edges are formed, should be hardened and tempered, while the bar as a whole should be strong and rigid, but at the permit of the knife made therefrom being straightened or fitted, to eliminate the warpings and distortions incident to the hardenalinement of the opposite edges. It is also essential that the lips or upturned edges be of such quality and texturethat they can be ground away, by successive sharpenings, guite or nearly to the bottom plate or backing. course give good cutting edges, but an allsteel stock, when hardened to the requlred degree, cannot be successfully straightened and adjusted by bending; and furthermore an all-steel stock is comparatively expensive and may not be produced with the requisite economy.

To produce composite stock of the shape specified and'having the requisite quallties, and that can be manufactured with ractical economy and success, my improve process is as follows: I prepare a fagot (Fig. 1) of the desired length, composed of a rectangular sectioned bar I of refined wrought iron, or soft steel (of ten per cent. carbon or less) of a dimension say three-fourths inch by one and three fourths inches, more or less, and two rectangular sectioned bars S of crucible caststeel ortool-steel, of. a dimension say one which latter are placed flatwise against the o posite edges 12 of the bodybard, with t eir respective edges 13 projectlng n either direction beyond the flat faces of sa d bodybar, as illustrated in Fig. 1 1n which form the members, previously heated and fluxed,

adjacent surfaces sufliciently to keep .the members together in place. when properly heated, is run through a pair of reducing rolls A, B, in a pass 1 hav ngan approximately straight top and bottom, and rounded or inclined ends that compress the exterior angles'of the billet and firmly weld the steel members to the opposl te edges of the body-bar, reduced as at 1 w1t h a somewhat crescentic shaped cross-sect on, as at S forming an overthrust of the upper and lower edges of the steel at the weld oint 5, as indicated in Fig. 2. The composite billet 1s l then further reduced in a pass 2, the form of same time sufficiently tough andbendable to j ing operations, or to" properly adjust the inch by five sixteenths inch, more or less,

are hammer-welded to primarily unite their This fagot,

i which presents a fiat at one side and a double channeled contour at the opposite side;

" V-shaped i "the top edges andv outer faces of the upstandwhereby the billet is given the s ape approximately as shown in Fig. 3, the intermedial portion I being reduced to about one half the thickness of the side portions S which latter are crowded inward at the corners 6. The bar is next inverted and put through a reducing pass 3 that flattens the body or backing portion nearly to its final thickness, as at 1 and transforms the edge portions into embryo upturned lips, as at S, forcing the lines of the welding into oppositely directed bird-mouth or V-shaped contour, as at 7, but leavin a proportional excess of thickness at the shoulder 8; the stock then having the shape approximately as indicated in when thus shaped is put through a final pass 4 of the rolls, whereby it is slightly reduced in its full width, the body portion flattened or further reduced to finished dimension for the backing, as at I, and the excess at the shoulders 8 reduced in thickness and forced upward making the upturned lips S at each edge, complete and of approximately uniform thickness therewith; and disposing the welding along the angle or base of the lips in such manner that the upstanding lips are substantially all hard steel, while the backing or body web is of iron or non-hardening material, as shown in Fig. 5. Thus roducing a firmly united composite stoc of channel-bar-section, with edges that can be hardened and tempered, and with a body that will permit of the straightening, twisting, or readjustment of the alinement of the knife after it has been tempered, and with the V-welds of the steel-edge overlap ing onto the softer material approximately a ong the angles, as at 9, in a manner that will avoid liablitiy of rupture in the weld in the process of manufacture; the stock presenting 3rd and efiicient upstanding lips along both e ges.

The class of machine knives for whichthis improved composite stock is produced, and for which itis peculiarly adapted, are the ledger-knives for lawnmowers and similar mechanisms, wherein a spirally bladed revolver is arranged to shear against astraight ledger knife. The finished knife made. from this cutter-stock is of approximately the same cross-section as that of the complete stock, as shown in Fig. 5; the knife being a piece of the stock of the required length,

suitably hardened andLtempered, and having ing lips simply ground, on the lines f and t, for giving the desired cutting .edges, and which can be re-ground and used until the entire upstanding lips are worn away, with-' out exhausting the qualityof the stock.

I am aware that a channel-bar shaped cutter stock of a non-composite nature has here- Fig. 4. The bar' tofore been employed, and I do not, therefore, herein broadly claim that shape, per se,

as applied to cutters; but so far as I am turing of such formed composite knife-stock,

prior to my invention hereinbefore set forth.

What I claim and desire to secure by Letters Patent, is-

1. The method of making double-lipped composite knife-stock, which consists in aplyingto each of the two edges of a rectanguar bar of wrought iron a bar of cast or toolsteel of greater width than the thickness of the iron, condensing this composite fagot to weld and form the steel in approximately crescent shape upon the res ective edges of the body-bar, reducing said bar with an excess of reduction centrally along one side; further reducing the same in channel-bar shape to form embryo lips of the steel having an excess of thickness at the shoulders where the welds embrace the edges of the iron, then rolling said reduced bar into its final doublelipped shape with the mass of disposed in the lips, and the welding hne along the base of the lip, substantially as set forth.

2. The improvement in the method of making composite stock for dual-edged ma steel chiefly f chine knives of the character specified, which consists in combining in a fagot, a rectangular sectional body-bar of iron or soft steel and.

two bars of crucible cast or tool steel respectively arranged with projecting edges upon the opposite edges of said body-bar, marily uniting the same by hammer-weld ng, and at an initial rolling compressing the exterior projecting edges of the billet inwardso as to overthrustthe steel edgings in opposite crescentic form upon the body portion, then reducing the. body thickness, and by successive stages subsequently forcing the steel edgings into the form of u standing lips at the respective edges, and c osing the welding lines into inwardly over-lapping bird-mouth or V -shaped integrations a ong the op osite edges of the backing body, substantia ly as set forth.

3. A composite stock for machine-kmves of channel-bar cross-section, said stock comprising an a proximately flat body-portion consisting 0 soft non-hardenable steel or wrought-iron, and offset upstanding longitudinal lips consisting of hardenable steel or tool-steel along each edge'of said body, the

body and lip portions being integrally united by'o ositely disposed V-shaped'weldings. longiififdinally along the junction line of the lip and body, as set forth.

4. The within described double-edged cqmlposite stock for machine-knives, said at the angle or up-turn-ofiset of the-respem 10 stoc comprising a flat non-hardenable centive lips, substantially as set forth. tral body-strip, in combination with an up- Witness my hand this fourth day of May standing outwardly inclined li of harden- 1908.

able steel uniformly a plied t ereto along FREDERICK SEARLE each of the edges, said ips being of approximately the same thickness as the body-strip, Witnesses: Q

and integrally united longitudinally there- 7 CHAS. H. BURLEIGH, with by oppositely disposed weldings located ELLA P. BLENUS.

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