US2361410A - Safety razor - Google Patents

Description

Oct. 31, 1944.

J. MUROS SAFETY RAZOR Filed Dec. 23, 1943 1 .EQH Q x g E 23 "M Wvavram Patented Oct. 31, 1944 SAFETY RAZOR Joseph Muros,'C'ambridge, Mass., assignor to Gil-. lette Safety Razor Company, Boston,'Mass., a

corporation of Delaware 7 Appueat'i n December 23, 1943, Serial No. 515,349

4 Claims.

.This invention relates to safety razors of the type in which a thin steel blade is flexed for shaving between cooperating blade-clamping members, asin the well-known Gillette type of against walls of their aperturesand the difference in edge exposure between opposite ends of the blade on the same side of the razor may-amount to several one-thousandths of an inch. This dissafety razor. 5 placement may be sufficient to render the razor The cap and guard members of such safety dangerous to the user or it may merely make its razors are provided respectively with correspondshaving efficiency variable, but in any case it iming projections and apertures designed usually to pairs-the desired precision of the razor as a shav- 'locate the blade accurately in shaving position ing instrument. Itis not practical to reduce the between them and also to-maintain the two mem- '10 manufacturing tolerances in the cap and guard bers themselves in parallel relation. It is im'- members sufficiently to overcome this defect withportant to maintain this relation since the edge out unreasonablyincreasing. the production cost exposure of the blade in the razor is determined of the razor parts and it is accordingly desirable by a 'plane tangent to the outer edgesof the cap to allow the same manufacturing tolerances and guard members. Therefore, if theseedges which have been found practical and desirable are not maintained parallel throughout their from a production standpoint. length the edge exposure of the blade will vary I have discovered that the problem created by from one point to another along the edge of the these circumstancesmay be solved by manufacrazor. For example, if the cap is twisted to any turing the cap and guard members so that the degree with respect to the guard the edge exrib or projection of one and the corresponding posure at diagonal corners of the blade will be slot or aperture of the other are permanently disexcessive in one case and scant in the other. posed at an angle which will compensate for the 'An'object of the present invention is to provide relative twisting movement to which the two parts a safety razor'so constructed and arranged that are subjected in the clamping operation. This accurate parallelism of'the edges of the cap and may be accomplished for example by inclining guard members will be established and mainthe slot of the guard several degrees from the tain'ed when these members are clamped together geometrical longitudinal'axis of the guard which, upon a blade. of course, is parallel to the line of the teeth or -Inmanufacturing safety razors as heretofore side edges of the guard. The effect of this disconstructed on a quantity basis it has been the placement is to locate the walls of the slot so that practice to'provide, in additionto the tolerances they Will a t as g u i g s rfaces toestablish and allowed in making the-individual elements, a tolmaintain parallelism of the cap, and guard edges erance clearance of .002', to .003." between the when the cap is twistedto the limit of movement projection or projections on one blade-clamping 'permitted'by the tolerances of and the tolerance member and the groove or apertures provided for clearance between the projecting Portions o On its or their reception in the other blade-clamping member and the apertured portions of the other. member. This is in accordance with well un- It will be apparent that the same advantageous derstood principles of production manufacture. results may be secured by inclining either the It happens, however, that the user almost invariaxis of the aperturesj or slot of one member or ably holds such a razor by the edges or teeth of 40 the axis of the rib or projections of the other the guard member in clamping the cap and guard member, so long as there. is an initial deflection together so that the clearance allowed for manubetween these two axes which will accurately facturing reasons is always taken up in the compensate for the twisting of the two razor clamping operation by a slight twisting of the members permitted by'manufacturing tolerance cap with respectto the guard member; that is 'of their dimensions. to say, the cap is turned with the handle at the These and other features of'the invention will conclusion of the clamping operation until the be best understood and appreciated from the folwalls of its rib, if that is the shape of its projeclowing description of one of the many possible tion, abut at opposite ends of the cap against embodiments thereof selected for purposes of ilopposite walls of the groove in the guard memlustration and shown in the accompanying draw-.- ber. The same condition persists in razors I ing, in which: wherein the cap is provided with pins or other Fig. 1 is a View in perspective on an enlarged projections and the guard with. corresponding scale of, the guard member of a safety razor showapertures; the cap will twist slightlyv until the ing a portion of the blade-locating rib of the projections at opposite sides of the handle abut cap positioned in its slot;

a readily understood.

Fig. 2 is a plan view of the razor on the same scale as seen from the top, portions of the cap being shown as broken away; and

Fig. 3 is a view in cross-section on the line IIIIII of Fig. 2, the blade being omitted in both views.

The guard member In of the illustrated razor is rectangular in outlineand providedalong each longitudinal edge with a series 'of guard teeth ll. Its blade-engaging face is generally convex in transverse curvature and includes parallel fulcrum shoulders l2 over which the blade is flexed when clamped for shaving. The guard member is provided with a central longitudinal slot [3 and this, as shown in Fig. 2, is not parallel to the longitudinal axis of the guard member comprises the cap [5, this being also rectangular outline but somewhat "i'iarrower than the guard. Its blade-engaging face is transversely curved and its parallel-edges are so disposed as to engage an interposed-blade behind its parallel cutting edges and flex it over the fulcrum shoulders 12' of the "guard. The cap is provided with abladeloc'ating rib l6 arranged to fit into the slot 13 of th guard. member with a clearance tolerance of about .003. A reeniorcing lug or projection I1 is provided at each of the cap corners. The cap isalso provided with a threaded central 'stem 18 which passes freely throu'gh'the aperture I4 of-ithe guard member l and is receivedin' the threaded upper end of the'liandlel9 of the razor. The rib I6 coincides "with-the longitudinal'axis of the cap l and is disposed in parallel relation with both of its outer edges.

In the accompanying drawing the blade has been omitted for the sake of clearness but its positionbetween'tlie guard it and the cap member or'tnei11ustratedsamty razor will be It "is, "of course, longitudinally 'slotted'tb'receive'the rib'lB, aperture'd for the passage o ftli e'stem l8 and notched at its corners'to clearthe'lugs l1. Assuming, therefore, that theblade'has'been properly-positioned between the "two members and "that the user holds the guard member at fibl 'osite "sides byits teeth with o e hand and rotates the han'd1e'l9 with the other hand a counter-clockwise direction, as' seen in 2, it will beapparent that in the final clamping turn of the handle 19 the cap 15 willbe 'twisted'also in a counterclockwise directioil'hhtil its rib H5 at its left end abuts against one 'wallof the slot I3 and at its right end against the other wall of the slot. However, the angular twist permitted to the cap by the tolerance of the'parts is arrested before the cap has passed through the position in which its edges are symmetrically disposed with respect to the guard L, The cap, therefore, is caught and held with the edges of the two members positively registered in parallelism by the gauging effect of the walls of the slot l3 on the walls of the rib it.

While the walls of the slot l3 in the guard act to gauge the rib I6 of the cap so as to establish exact parallelism of the critical edges or surfaces of the two blade-clampin members, they permit the user to release slightly the clamping pressure of the cap on the blade, if this should become desirable in order toincrease the edge exposure of the blade for the current shaving operation, all without any disturbance to the correct positions of the clamping members. The spring pressure of theinterposed blade tends to retain the cap in the position to which it has been moved in the final clamping rotation of the handle, and it is only when substantially all clamping pressure is removed that the capis permitted to leave this predetermined position-in the razor.

Having thus disclosed my invention and "dc-'- scribed a preferred embodiment thereof,'Iclaim as new and desire to secure by Letters Patent:

1. A safety razor having cooperating bladeclamping members with outer parallel surfaces which determine the edge exposure of a blade interposed between them, and rotatable means for clamping said members together, one memher having a projecting configuration parallel to its outer edges, and the other having 'a corresponding recessed configuration disposed 'ata slight angle to its outer edges.

2. A safety razor having cooperating bladeclamping members with outer edges shaped to determine the edge exposure or a blade interposed between them, and rotatable means for clamping said members, the said members having corresponding projections and recesses varying in dimensions by a predetermined tolerance clearance and the axis of the projections in one member being ang'ularly displaced with reference to the axi of the recesses of the other member when the two members are disposed with their outer edges in parallel relation.

3. A safety razor having cooperatin cap and guard members, one provided with a slot and the other with a rib to be received in said slot with-clearance and to locate one member with respect to the other, the axis of the rib being parallel to the axis of one member'and the axis of the slot being disposedata slight :angleto the axis of theother member. 7

4. A safety razor having cooperating cap and guard members,-e'a'ch with meansmaking' contact with each-other to locate the said members in parallel relation-the means onone'meniber being disposed parallel to the axis ofthe member whereon it isl'o'c'at'ed and the'meanson the other member being disposed at aslightangle to its axis.

JOSEPH MUROS.

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