US1813470A - Safety razor blade - Google Patents

Description

J y 1, 1931 R. E'THOMPSW 8 3, 10

SAFETY RAZOR BLADE,

Filed Feb. 11. 1930' Patented July 7, 1931 UNITED STATES PATENT "oFF CE RALPH n. ri-roiurson, or ianooxnmn, MASSACHUSETTS, AssIoNon TO GILLETTE SAFETY nazon COMPANY, or BOSTON, MASSACHUSETTS, A conrona'rron or DELA- sunwniizoa BLADE Application filed February 11, 1930. Serial No. 427,496.

This invention relates to safety razor blades. of the thin flexible type which are bent transversely and maintained in a condition of curvature when clamped in the L holders "in which they are used.

In bending and clamping the blade stresses are 'set up of which it is desirable to relieve the cutting edge of the blade and the material adjacent thereto. This-l have accomplished in accordance with the invention 0 my prior application ScrrNo. 410,220, filed November 27, 1929, by providing an I elongated slot in the axis of bending, thus concentrating the stresses of the blade in its end portions where they can be dcalt'with without consideration for the degree of hardness required in the cutting edges of the blade. The slot having this function or portions thereof may be advantageously utilized in connection with ribs or studs in the holder for the purpose of accurately locating the blade. In one aspect accordingly the resent invention consists in a further deve opment' or carrying forward of the construction of my earlier application with a view to providing a blade of great durabilit and of eliminating danger of breakage 0 the critical or blade locating edges of the slot. This I accomplish in accordance with the present invention by providin softened zones or areas -in the material of the blade which include those edges which are relied upon for locating the blade.

In order that the blade may be used, with holders of different models, it is desirable to provide the blade with an aperture of such outline as to define oppositely projecting tongues for engaging projecting portions of different shapes upon the holders. For

example, the aperture may be shaped so as to locate the blade with respect to a central longitudinal rib or with respect .to a pain of spaced cylindrical studs. Under such circumstances, the aperture may include outwardly extending recesses having oppositely disposed tongues shaped to engage opposite sides of cylindrical studs while the edge portion of the slot remaining outside the recesses me be utilized to engage thewallsof a blade coating rib. In accordance with illustration andshown in the accompanying drawing in which the view of the blade. v r

The blade shown in the drawing is of thin flexible steel, sharpened at each edge for cutting and having curved lateral or end edges. It is provided with a centrally disposed longitudinal slot 16, located symmetrically in the blade and accordingly at its axis single figure is a plan of bending when curved transversely. The

slot is substantially as long as the effective I cutting edge of the blade and rounded atits extremities. The slot may be of such width as to accommodate an elongated rib projecting from the cap or the guard of the holder and consequently its opposed edges may be termed critical edges since they determine the location of the blade and the amount of its exposure with reference the guard.

The blade herein shown is provided with spaced" apertures 12 which are intersected by the slot 16 and which in outline define a pair of oppositely disposed tongues 14, projecting toward each other but spaced apart by a distance greater than the width of the slot. The opposed inner edges of the tongues 14:, therefore, constitute critical edges in that theymay be used to locate the blade with respect to studs of cylindrical or other contour. Each of the tongues 14: is set off from. the aperture into WhlCh it projects by outwardly extending recesses which form a part of the apertures. As herein shown the blade is provided with softened areas 18 of a shape roughly semicircular as suggested by dotted lines. The exact shape of these areas is of secondary importance so long as they include the stud engaging edges of the aperture. '-.I prefer, however, to includealso within the softened areas, some portion of the edge of the aperture adjacent to such critical edges. In a blade apertured, as herein shown, it is desirable to include the vertex of the recesses which bound the tongue 14 and accordingly I have shown the softened area as oval or semi-circular in shape and as including the tongue 14: and the blade material adjacent to the root thereof and includin also a substantial .portion of the outer e ge of each of the bounding recesses. The softened areas in all cases terminate within the cutting edge of the blade so that there is no impairment of the even temper of the edge.

' The softened areas 18 may be produced in any convenient manner and may be located wherever desired in respect-to the aperture of the blade. ,l'. prefer to form these areas by a supplemental operation after the blade has been hardened and tempered. Such a step may be carried out by clamping the body of the blade between water cooled clamping members shaped to expose the desired areas and then momentarily subjecting the areas to be softened to the action of an annealing flame. The effect of the flames'is to draw the temper of the exposed areas of the blade, while the clamps conduct heat away from the untreated portions so rapidly that their temper is unaffected. The portions of the blade areas, each including one of thetonguesand' extending to the margin of the slot on either side thereof. a

4. A thin flexible blade for safety razors,

having'a tempered cutting ed e and an internal aperture in the shape 0 a slot intersecting a series of wider recesses each provided with a critical edge is its outline, the blade being softened in a number of separaterelatively small areas each including one side only of one of said recesses.

RALPH E. THOMPSON.-

in the softened areas, which include the critareas spaced longitudinally ,from each other and embracing in their areathe entire contour of said tongues and recesses.

52. A flexible safety razor blade apertured I to receive a positioning stud'and having inwardly directed tongues with stud-engagingends, the aperture being widened-adjacent to each side of the tongues, and lthe material of the blade being softened iii-substantially semi-circular areas, spaced longitudinally from each other and includin 581d recesses and the adjacent margins of e aperture.

3. A double edged flexible blade for safety razors, having an elongated centrally disposed slot for receiving a blade-locating rib,

and stud-receiving apertures intersected by.

said slot, the outline of each aperture de;

fining an inwardly projecting tongue and the material of the blade being softened spaced sis

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