US2171888A - Shearing head - Google Patents

Description

Sept. 5, 1939. D. T Q'CONNOR 2,171,888

SHEARING HEAD Filed Feb. 25, 1938 ly-Z5 Patented Sept. 5, 1939 UNITED STATES PATENT. OFFICE 3 Claims.

My invention relates to improvements in shearing heads for electrically driven hair clippers and dry shavers. More explicitly, the purpose of the invention is occupied with a clipper or razor of the dry shave type, providing for the removal of the toughest beard without injuring the tenderest skin, giving a superior shave because it is peculiarly suited for severing hair at its closest contact with the skin.

My invention purports the provisions of a clipper or shaver of this type consisting of a device, extremely simple in construction, of few parts, sturdy and exceptionally easy to use, efficient in operation, sanitary and inexpensive to manufacture, applied without the use of shaving soap and utterly devoid of the slightest danger.

The invention may be grasped more readily from the following description in conjunction with the accompanying drawing.

Figure l is an elevational view of an electric razor with my improved cutter.

Figure 2 is a partial side elevation thereof.

Figure 3 is an enlarged partial cross section of the shearing head, taken approximately on the line 3-3 of Figure 1.

Figure 4 is an enlarged fragmentary sectional view of the cutting unit taken along line 4-4 of Figure 2.

Figure 5 is a partial, enlarged cross section of the cutter showing a modification of the tension device and the lubricating pad.

Figure 6 is an enlarged partial cross section and elevation of a modification embodying some of the principal improvements of the device.

Figure 7A is a greatly enlarged partial plane view of the slot details of the outside cutter.

Figure 7B is a greatly enlarged fragmentary plane view showing slot details before the outside cutter is formed.

Figure 7C is a greatly enlarged partial elevational view illustrating outside cutter slot details.

Figure 8A is a greatly enlarged partial cross section of the inside cutter taken approximately on line 3--3 of Figure 1.

Figure 8B is an enlarged partial plane view of the inside cutter showing tooth details.

On the drawing, Figures 1 and 2 illustrate how the cutter is arranged in any suitable manner on a hollow handle or tool I00, in which is arranged some sort of motor IOI, which may be connected to an electric outlet by means of lead wires I02, extending from the bottom of the machine. .A slot I03, in the top of the motor case I00, receives the bottom of the outside cutter I04, which Is secured therein by a set screw I06, engaging the, corresponding i'nterlor screw I26, arranged on the case.

The outside cutter unit gle arm plate I08, a steel plate IIO, spot welded to form a rigid outside element. The inside cutter III, is formed from a fiat piece so that its section, Figure 3, is approximately U-shaped.

In Figs. 3 and 4, the tension pad I I2, is a pliable 10 rubber strip with a suitable clearance hole for the work arm II3 of the motor. The work arm H3 passes through the clearance hole in the bottom of the outside cutter insert, through the rubber pad opening and engages in a notch III, in the bottom of the inside cutter. This work arm I I3, moves with a reciprocal or vibrating motion, moving the inside cutter III, to and fro while the outside cutter I0! remains stationary. Hair enters the outside cutter slots Ill and as the ingo side cutter reciprocates it effects the necessary shearing action between the edges of the inside cutter teeth H6 and the outside cutter teeth II5.

One of the principal difficulties encountered by the manufacturers of shearing heads is in maintaining an even, constant, light tension between the stationary and moving cutters. I have accomplished this efiect by means of a novelshaped outside cutter arm plate I08 and a tension pad H2, of rubber or a similar springy material. The unique outside cutter arm is sturdy.

In assembling, the upper toothed side may be bent up or down slightly into approximately its proper position at which it is slightly flexible. The inside cutter III, is then inserted on the rubber pad which supplies the remaining necessary tension. The advances in the rubber industry make possible the use of such a pad, pliant and resilient enough to permit the inside cutter III to make its reciprocating motion and also to 4 absorb any slight eccentricities in the shape or angles of either the inside or outside cutter. There is no relative movement between the faces of the rubber block and the faces of the cutter and the housing, the movement being obtained I01, consists of an aninsert I09, and a wall 5 l by the internal movement of the rubber itself.

Another fault found in the shavers now on the market is the lack of adequate lubricating facilities for the cutters. The lower section of the outside cutter I01, on my improved shearing head, formed by the outside'cutter wall IIO, the angle arm plate I08, the angle arm plate lugs I04, bent to fit securely around the outside cutter insert I 09, and spot-welded into a rigid unit, thus forms both a pocket or receptacle for a 5 lubricating or tensioning device. The rubber tension pad described above may be replaced by a similarly shaped absorbent felt pad, Fig. 5 III, which may be soaked in oil or other lubricant. This pad, Ill, may be cut away at either end, as illustrated in the partial cross section Fig. 5, taken on approximately 4-4 of Fig. 2, to suitably accommodate a ball bearing H9, which will be lubricated indefinitely by the oil-impregnated felt pad. Using a ball bearing will substantially reduce the total contact area between the cutters, hence reducing friction and minimizing the load on the motor. Theyfelt, the balls or the rubber may be used above 'or in any combination. when substituting the felt and balls, a lighter gauge metal, preferably non-corrosive, may be present will cut hair,

more satisfactory, since a little more tension is required when the rubber pad is not employed.

Many men object to dry shavers because they claim the dry shaver does not give a "close" shave and is too slow. Most dry shavers on sale at if you can coax it into the proper slots. This results in "slow and not very "close shaving. My improved shearing head overcomes these objections by means of the novel shaped slots or teeth of the outside cutter.

These slots, Figs. 7A, B and C, ill, are located along the top edge of the outside cutter and parallel to one another extending down over the cutting plane Fig. 3 ill, and ending short of the edge of the cutter, so that the teeth are rigidly embodied in one piece, namely the ouside cutter.

angle arm plate Ill. It is to be noted that these teeth are bent at an angle over the tips of the inside cutter teeth Fig. 3, H6, and extend well down past the plane of contact of the inside and outside teeth. Thus hair is readily admitted into the slots and the cutter rides smoothly on the skin. Of prime importance is the shape of these slots. They are essentially in the shape of tear-drops, Fig. 713 Ill. The wider end of the slot admits the hair, the slot then narrows down to approximately the thickness of a single hair at the root of the tooth. The slots at the roots of the teeth actually have an opening equal to the thickness of a single hair.

The inside cutter, Fig. 8A, III, a section of which is generally U-shaped and rigid with teeth formed by interdental spaces along at least one lateral edge, has more teeth than the outside cutter. This tends to keep the shearing head from clogging by permitting sheared hair to drop into the recess in the cutter immediately they are sheared and also results in a faster, smoother-feeling shave.

A side wall of the inside and outside cutter has been omitted in the design, hence, this sheared of! hair which drops into the cutter is immediately ejected from the recess which has three open sides.

Hence the cutter is clog-proof, a so far unattainable goal of the present day dry shaver manufacturers. The inside cutter teeth, Fig. 8A H6, when viewed laterally, unlike similar teeth which have a rounded bevel, taper to a sharp edge. Insidecutter teeth so shaped are extremely important in this shaver as, in conjunction with the novel shaped and placed slots in the outside cutter, they easily pick up hairs which may lie close to the skin as the shearing head is drawn across the skin, giving the user a fast, clean, close shave. This idea is contrary to the present belief of dry shaver manufacturers, most of whom assert that the outside cutter does the combinll or picking up of close-lying hairs; however, in practice, I have found that the tapered or untapered tooth determines to a considerable degree whether the cutter is slow or fast. An inside cutter may also be fashioned of a sumciently light gauge material non-corrosive or plated metal, so that when placed in the outside cutter it will tend to spring open slightly, so exerting a tension on the outside cutter.

Figure 6 shows a possible modification of my improved cutter embodying several of its salient features.

One versed in the art may discern from the above description and drawing that this cutter may be manufactured with comparatively few dies and operations, that its assembly is simple, and hence it is economical to manufacture.

It will be further seen that this improved cutter is easy to use, the cutting action being mainly against the grain of the hair. It cannot clog with hair due to the dispatch with which hair is ejected and it will speedily cut cleanly and closely any type of hair.

Hence I claim as new and patentable:

1. A dry shaving unit consisting of a housing. a stationary toothed outer cutter secured to said housing, a reciprocating toothed inner cutter mounted on said housing, and a pad of rubber interposed between the housing and the lower face of the inner cutter so as to exert pressure on the upper face of the inner cutter against the inner faces of the cutter teeth of the outer stationary cutter.

2. In a device of the character described, a housing, a shearing head comprising a stationary outer cutter secured to said housing and having in cross-section substantially the form of a V lying on its side with the upper arm of the V elongated and extending beyond the lower arm, an inner reciprocating cutter mounted on said housing and having in cross-section substantially the form of a U lying on its side, the upper arm of said U having teeth in its extremity lying adjacent the undersides of said teeth of said outer cutter, said V-shape of said outer cutter enhancing the resilient pressure of said'toothed end thereof against said toothed extremity of said inner cutter.

3. In a device of the character described, a housing, a shearing head comprising a stationary outer cutter secured to said housing and having in cross-section substantially the form of a V lying on its side with the upper arm of the V elongated and extending beyond the lower arm, an inner reciprocating cutter mounted on said housing and having in cross-section substantially the form of a U lying on its side, the upper arm of said U having teeth in its extremity lying adjacent the undersides of said teeth of said outer cutter, said V-shape of said outer cutter enhancing the resilient pressure of the said toothed end thereof against said toothed extremity of said inner cutter, and a pad of rubber interposed between the housing and the lower face of said inner cutter so as to exert pressure on said toothed extremity of said inner cutter against said toothed end of said outer cutter.

DONALD T. O'CONNOR.

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