US2216673A - Electric shaving device - Google Patents

Description

Oct. 1, 1940.

P. K. M GALL ELECTRIC SHAVlNG DEVICE Filed Oct. 1, 1936 Exit-E 30 The universal joint Patented Oct. 1, 1940 PATENT- .oFFl j 2,216,673 ELECTRIC snsvmc DEVICE Philip K. McGall, Newark, N.

Metal Works, Inc., Newark, N

of New Jersey J., assignor to Art 1., a corporation I Application October 1, 1936, Serial No. 103,571

' Claims. gel. so-4 a) The invention relates to shaving devices .and has as an object the provision of a device of this character wherein the movable memberis resiliently held to its work.

5 It is a further object of the invention to provide a device of this character having novel means for the clearing out of severed hairs.

It is a further object of the invention to provide a device of the character referred to embodying improvements in details.

Further objects of the invention will appear from the following description when read in connection. with the accompanying drawing showing an illustrative embodiment of the invention, and wherein:

Figure 1 is a side elevation:

Fig. 2 is an end view as seen from v the left of Figure 1;

Fig. 3 is a detail central vertical section on line 3-3 of Fig. 2 drawn on a larger scale;

Fig. 4 is a vertical transverse section on line 6-4 'of Figure 3; and

Fig. 5 is a detail transverse section of a cutter bar on an enlarged scale.

As shown the device comprises a handle it) enclosing an electric motor il provided with a plug socket i2 and designed to operate the cutting device through the shaft it of the motor through the medium of universal'joint means M. means is necessary because of the angle at which the cutter casing i5 is placed with respect to the handle Ill.

The casing it is formed with a cylindrical bore it in which revolves a rotor ll; which rotor is formed with a helical rib i8 presenting a helical cutting edge. The casing I5 is shown as formed with a plurality of slits l9 defining a plurality of cutter bars 20, each cutter bar presenting at one side a cutting edge at the inner surface of the bore. 4 Y a I The skin-contacting surfaces 'of the cutter bars are desirably formed upon a curved surface as indicated in Figure 5 to allow the skin to protrude slightly between the bars in a manner well known in the art in order to secure a closer shave.

Dimensions for the device which are found to be satisfactory are a diameter of substantially three-sixteenths of an inch for the outer edges of the helix and with a pitch of the helix of substantially thirty turns per inch. With these dimensions and this pitch, the angle of the hellcal cutting edge to the axis of the rotor is substantially 3.25 degrees. It is'foundthat if theslits separating the cutter bars 21 are at right angles to the axis, the resulting angles of the helical turns to the cutting edges carried by the bars of substantially 3.25 degrees will tend to cause the hairs to be dragged laterally before they are severed, resulting in a pulling on the 3 beard. On the other hand, if the angle between the helical cutting edge and the edges carried by the bars is too small, the hairs will tend to be rolled along.

It is therefore preferred as shown to form the m slits l9 separating the cutter bars at an angle to the axis of the rotor and it has been found by experiment thatwith the rotor formed as'described,- this angle of the slits to the axis should be about 2.50 degrees, thus providing an angle 1' between the relatively moving cutting edges of substantially .75 of a degree. This angle is found to be somewhat critical and it is at present preferred to make this angle not substantially more than one degree or less than about .50 of a 20 degree. The operative part of the helix it is made slightly smaller in diameter than at its ends, in order that non-operative portions 2!, 22 of the helix may contact the casing while the operative parts of the helix are preserved slightly 35 out of contact with the cutter bars, being spaced less than the diameter of a hair therefrom.

To hold the rotor I! to its work, there is shown a presser bar 23 carried in a recess 24 in the casing i5 and resiliently pressed against the rotor so as by a compression spring 24'. The casing It" is shown as retained in the extension 25 of the handle by means of a screw 28.

The casing It may be readily removed from the bore. To prevent the presser bar being forced down into the bore upon the removal of the rotor, the recess 24 is desirably formed in I the shape of aT as shown, the presser bar being 49 of a like configuration whereby the shoulders upon the presserbar may engage the complemental' shoulders of the recess to. support the bar. The presser bar' also may be slid out of the recess whether the rotor is removed or not.

The extension 25 is shown as removably mounted in the handle, being retained in recess 21 in its end by means of, a set screw 2: and located by apin 29 projecting from the handle portion l0 into a hole 30 in'the said extension 2'. 50 To allow for'escape of hairs severed by: the rotor, the casingis shown as provided with a plurality of windows 3| upon each side of the casing adjacent the upper turns of the helix IS. Asthe" the handle extension when freed by removal of as screw "26. when the'rotor maybe slipped out of helix revolves a current of air will be produced 5 into one of the windows SI and out of the opposite window upon the other side of the casing,

thereby effectually ejecting the severed hairs.

, The action of the presser bar 23 provides that I in case of wear causing more than the necessary running clearance of the rotor, the contact of the end portions of the helix at the points 2|, 22 will be maintained and therefore the clearance between the coacting cutting edges will always be the same, and in addition, any chattering will be eliminated to provide a quiet running device.

Minor changes may be made in the physical embodiment of the invention without departing from the spirit thereof within thescope of the appended claims.

I claim:

l. A shaving device comprising, in combination: a rotor comprising a solid core and a helical cutting edge carried by said core; a casing having a bore enclosing said rotor; transverse cutter bars carried by said casing at one portion of said bore and spaced longitudinally thereof; a cutting edge carried by each bar to coact with said helical cutting edge; means to drive said rotor; said casing havng an opening in its side wall above said bars for escape of severed hairs.

2. A shaving device comprising, in combination: a casing having a bore; a series of transverse cutter bars carried by said casing at one portion of said bore and spaced longitudinally thereof; a cutting edge carried by each of certain of said bars; a rotor revoluble in said bore; a helix presenting 'a helical cutting edge carried by said rotor; said helix contacting with the wall A of'said bore at each end of said helical cutting edge and the latter revolving out 01' actual contact with said bars; a presser bar engaging said rotor at its ends and diametrically opposite said -cutter bars; resilient means acting through said carried by said member in coacting relation with said first named cutting edges; a presser bar having portions complemental to the portions of said passage, seated therein and contacting said member; spring means pressing said bar against said member; and means to cause relative movement between said cutting edges.

4. A shaving device comprising,- in combination: a casing having a cylindrical bore; transverse cutter bars carried by one portion of the bore and spaced longitudinally thereof; a rotor mounted in said bore; a helical rib carried by said rotor; at least one turn of the-rib at each end of the rotor exceeding in diameter the intermediate turns thereof; a presser bar contacting said excess diameter turns; and a spring to act through said bar to urge the rotor toward the cutter bars.

5. A rotor for use in a shaving device compris-

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