US1744803A - Razor blade - Google Patents

Description

Jan. 28, 1930. o. ROTH RAZOR BLADE Filed July 50, 1 928 h the arched guard pl Batented Jan. 28, 1930 [TE STATE PATENT FFICE RAZOR BLADE Application filed July 30, 1928, Serial No.

My invention relates to razor'blades, more particularly those having two cuttin ed es,

i such as are used with the so-calle sa ety razors, in which when in use, the blade is i clamped over an arched indented guard plate.

Razor blades of'this kind are made as thin as possible both to improve their cutting 'capacityand to facilitate bending them over ate. A certain limit is set to this effort by the fact thatthe resistance of the blade'tobending stresses, more particularly to those in planes parallel to the cutting edge, must not be toov small, as otherwise the blade may easily be fractured, especially when being clamped in the safety razor. In this respect the middle parts of the blade, which are, already weakened by the holes for the pins of the safety razor, are specially endangered; Hence, in practice it is of no use to grind the whole of the blade surface evenly to the same thickness. It is also not possible to grinddown the blade in separate stripes running parallel to the cutting edge, as this would produce dangerous cross sections extending over the entire length of the blade, which might easily cause the blade to break-along the said stripes.

Now, I have foundthat these disadvantages may be avoided by the blade being ground in zig-zag, serpentine or like stripes such that the weakening zones caused by the grinding do not extend straight fromend to end of the blade and therefore cannot be the cause of fractures even when the blade is heavily stressed ,in the transverse direction. This eifect can be still further increased by the grinding. stripes being'ofi-set with respect to one another on the two sides of the blade. -With these and other objects in view, the nature of which will more fully appear as the description proceeds, my'invention consists in the special formation and arrangement of the grinding zones of the blade.

represent to a greatly en ged scale two preferred embodiments of my invention, Fig. 1 shows one half of a blade made in accordance with the invention. Fi 2 is a cross section on the line IIII of tion in Fig. 2 is out of proportion in order to In the accompanying drawings, whichig. 1. The illust'ra 296,384, and in Germany March 19, 1928.

make it more clear; in; reality the dimensions as regards the thickness are considerably less as compared with the breadth of the blade.

j Fig. 3 shows in the same mode of represents.

tion as Fig, lamodification. p In the rawing the ,places Land 1 which are ground in accordance'with the invention,

are shaded, while the places or zones 2 and '2? which substantiallyretain their original level,-are left plain. Aswillfbe seen from as Figure 1, the ground stripes extend in a zigzag or serpentine fashion in the longitudinal direction of the blade onboth sides. of the same. The middle part of the blade, which contains the holes 3 and 4 for slipping over 65 the pins of the safety razor is preferably left, at least on one side, in its original thickness.

The outer grinding stripes 1 of the side of the blade visible in Figurel mer e directly into the cutting edges 5, 5. nground stripes may of course adjoin the cutting edges, as is the case in the constructional example showhat 2 in Fig. 3,

It will be seen that within therange of the ground places, except at the extreme edges, every line drawn parallel to the cutting edge alternately strlkes thinly ground and unground parts of the blade, in other words that there are no weakening lines extendin right along in the longitudinal direc- 8o tion 0 the blade. In this arrangement not only the cutting edges themselves but the parts of the blade lyin in the vicinity are of the desired slight th ckness desirable for having a good cutting ca acity, and the flex- 86 ibility of the blade as a w ole is considerably increased, as compared with the case of a blade ground in the ordinary way.

The grinding stripes 1', 1 may, of course, have a different form and be provided in a 90 greater or smaller number and in a different position. Or they may be made broader or narrower; they also need not extend throughout the entire length of the blade. They may, as for instance as" shown in Fig. 3, be more ser entine or more like a sine curve. Such aorm is obtained, for instance, if the grinding be carried out in such a manner. that the grinding discs during the passage of the blade in its longitudinal directionperform for instance a reciprocating motion derived from a circular motion through the intermediary of a crank or the like. c

As will be seen from Figure 2,-the grinding stripes 1, 1, may be ofi-set with respect to one another on the two sides of the blade, such that opposite a grinding str1 e on one side there is a stripe of untouche material on the other side, so that the wcakenings caused by the grinding do not have an additive effect.

The grinding stripes may, as indicated in Fig. 3, also be oil-set with respect to one another in such a way that the projections of two serpentine stripes laying opposite each other on the two sides @r the blade Will cros's one another. 7

The use of blades ground in accordance with my invention has the further advantage that, in contradistinction to the blades as hitherto generally used, which bend particularly readily in the middle where the holes lie, they bend substantially equally) over the entire width of the guard plate, as, owing to the peculiar form of the grinding stripes, the material is equalized in the separate clamping planes. By this meansa considerably more favourable cutting angle is produced at the cutting edges,

I claim: 7

1. A blade for safety razors having on both sides a plurality of thinner ground zones in the form of wave-lines extending substantially in the longitudinal direction of the blade. 7 p

2. A, blade for safety razors having on both sides a plurality of thinner ground zones in the form of wave-lines extending substantially in the longitudinal direction oi. the blade, the ground zones of the one blade side being off-set with respect to the ground zones of the other blade side. I

3. In a blade for safety razors, having holes in the longitudinal middle line groups of thinner round laces on each side of said middle llne and aving the form of to and fro stripes extending in the longitudinal direction of the blade.

4. In a blade for safet razors, having holes in the longitudinal mi dle line, a plurality of thinnerground places having the form of wave-like stripes extending substantially in the longitudinal direction of the blade sym metrically at each side of said middle line.

In testimony whereof I ai fix m si ature.

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