US2184180A - Safety razor - Google Patents

Description

C. R. FAIREY SAFETY RAZOR Dec. w, 11939.

2 Sheets-Sheet 1 Filed Feb. l, 1938 ll- 19, 1939. c. R. FAIREY 2,18480 SAFETY RAZOR Filed Feb. 1, 1958 2 sheets-sheet 2.

Bil

Patented Dec. 19, 1939 UNITED STATES PATENT ori-ice Appucaumrebruary 1, 193s, serial No. 188,178 In Great Britain January 8, 1937 3 Claims.

This invention is directed to a safety razor of the type in which a rotary cutter having helical blades coacts with a fixed blade to provide the cutting action.

An object of the invention is to provide a safety razor having an improved rotary cutter.

Another object of the invention is to provide a rotary cutter having widely spaced cutting blades, so that a smooth cutting action is obtained, and a number of non-cutting driving teeth sumcient to allow the rotor to be driven at an adequate speed.

A further object of the invention is to provide a rotary cutter which can be driven smoothly, but in which the number of cutting edges is not so great as to prevent a clean cutting action thereof.

Generally these objects oi the invention are obtained by producing a rotary cutter having a plurality oi helical cutting and driving blades thereon, and interposing additional non-cutting driving teeth between and of less height than these blades, so that the blades are effectively spaced from one another, wliiie at the same time the blades plus the additional driving teeth provide an adequate means of driving the rotor.

The means by which the objects of this invention are obtained are more fully understood with reference to the accompanying drawings, in which:

Fig. l is an end View of the head of a razor, partly shown in section, to illustrate the position of the novel rotor therein.

Fig. 2 is a plan view of Fig. 1, partly shown in section.

Fig. 3 is a side view of Fig. 1.

Fig. 4 is a side View of a detail of the rotor mounting construction.

Fig. 5 is a plan view of Fig. 4.

Fig. 6 is an end View of a modied form or the razor head, partly shown in section.

Fig. 7 is a plan view of Fig. 6.

Fig. `ii is a sectional View on the line 8-8. of Fig. 6.

Fig. 9 is a sectional View on the line 9-9 of Fig. 7; and

Fig. l0 is an elevational View of the novel rotary cutter. l

In Fig. l, a is a shaft extendingl from a conventional form of motor drive, as an electric motor, housed within the razor, this shaft terminating in a worm gear b.

A rotary cutter having cutting blades c 'extends transversely of the cutter head. Fixed blade e is secured to head d by screws o, and

(Cl. Sil-43) partially covers the rotor. An angled extension plate g is mounted beneath iixed blade e and is likewise fastened to the cutter head by screws o. A guard f is secured to the head by screws d, and has teeth q extending over the rotor.

It is noted that xed blade e is hollow ground so that its cutting edge is tangential to the rotary cutter.

Ends y' of the cutter are mounted in bevelled edge bearing plates lc, lc, these plates being slidably mounted in grooves formed in the razor head d, and pressed toward blade e and teeth q by springs m mounted in borings n.

Cutting blades c on the rotor are in the form of long pitch multi-threaded helices. non-cutting gear teeth h are disposed between the cutting blades, these additional gear teethI being mounted centrally of the rotor where they, as well as the cutting blades, are engaged by worm b on shaft a.

The rotary cutter in Figs. 6 to 9 is similar to that shown in Figs. 1 and 5, except that the cutting blades c are formed as cutting edges only on the non-driving side thereof, note Fig. 9. The ends 9' of the cutter are journalled in the bifurcated ends of cylindrical plunger r, urged toward the end of head d by springs s tted into the head of the razor. In this case the xed blade and the toothed guard are constructed from a single plate integral with the head d, the Xed blade being formed by hollow grounding the plate to form a cutting edge t, note Fig. 9, and the spaces between the teeth q.

Rotary cutter c is shown more particularly in Fig. 10 wherein the high pitch blades are undercut on their non-driving sides to form cutting edges. The provision of the additional driving teeth h of less height than the cutting teeth is quite advantageous. In the design of a rotary cutter driven in the center, two conflicting requirements become very pronounced when the diameter is made small enough to permit of a cutter head or housing of reasonable dimensions. One requirement lies in the fact that a high speed is necessary to obtain a clean shearing action which cannot be felt by a user, but this results in an exceedingly small time interval between the contact of a rst and a successive cutting blade on the rotor with the xed blade on the head. The speed and comfort of a shave is consequently improved by spacing the cutting teeth as far apart as possible to increase this time interval. In addition to the lack of comfort in shaving. the presence of too many cutting teeth acts as a brake on the movement of the 56 Additional it razor across the skin, as the hairs do not have time to present themselves properly to the cutting blades unless the razor is moved very slowly. A second requirement lies Vin the need for a greater number of teeth than the preferred use of a few number of rotating cutting blades allows, in order to drive the rotor properly, as the iive teeth formed by the cutting blades c shown in Fig. 9 would not engage smoothly with the .driving gear b.

The solution for these two opposing requirements is to increase the number of teeth for the center part or driving part of the rotor. Thus by providing these additional teeth h and making them of slightly less radial extent from the center of the rotor than the cutting teeth,

the reduction in radius being slightly greater than the diameter of human hair, the hairs are then merely brushed by these extra teeth instead of being sheared, and this therefore eliminates the braking eiect previously referred to, and allows a proper driving of the rotor without the decrease in comfort which would occur were these teeth also cutting.

Having now described a means, by which the objects of this invention may be obtained, what I claim as new and desire to secure by Letters Patent is:

1.. A safety razor comprising a rotary cutter, gear means for driving said cutter, said cutter having two sets of gear teeth arranged in alternation and both adapted to be engaged and driven by'said gear means. and one set of said teeth being of greater radial dimensionvthan the teeth of the other set, and being formed as helical cutting blades.

2. A rotary cutter for a safety razor comprising a rotor, gear teeth on said rotor, and a plurality of spaced high pitched helical cutting teeth mounted longitudinally of said rotor and disposed alternately between said gear teeth, said cutting teeth being of greater radial dimension than said gear teeth.

3. A rotary cutter for a safety razor comprising a rotor, gear teeth on said rotor, a plurality of spaced high pitched helical cutting blades mounted longitudinally of said rotor, each of said blades being of greater radial dimension than said gear teeth, and being undercut on one edge' thereof to form a cutting edge, and having the edge opposite said cutting edge formed as a driving edge, said gear teeth being alternately disposed with said cutting blades about the mid-section of said rotor.

CHARLES RICHARD FAIREY.

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