US2640261A - Transmission for electric hair clippers - Google Patents

Description

June 2, 1953 L. J. WAHL' 2,640,261

TRANSMISSION FOR ELECTRIC HAIR CLIPPERS Filed Jan. 2, 1951 3] I: if in elzforf miga/ta Z fll torvzy Patented June 2, 1953 TRANSMISSION FOR ELECTRIC HAIRY,

oLIPPEns Leo J. Wahl, Sterling, Ill., assignor to Wahl Clipper Corporation, Sterling, 111., a corporation of Illinois Application January 2, 1951, Serial No. 203,975

4 Claims. 1

My invention relates generally to an electric hair clipper of the vibrator type, and more particularly to a mechanical transmission for establishing a connection between a vibrating element and a movable cutter blade reciprocated thereby.

The invention constitutes an important improvement over the mechanical transmission disclosed in my prior Patent No. 1,582,320 dated April 27, 1926.

The hair clipper with which my invention is used comprises a casing, a fixed cutter blade mounted at one end of the casing, and a movable cutter blade adapted to reciprocate back and forth on th fixed blade. The movable blade is driven by the moving element of an electromagnetic or other vibrator through the agency of my improved mechanical transmission. Since electromagnet vibrators are most commonly employed in electric clippers, the moving element will hereinafter be referred to as an armature.

One object of the invention is toprovide a mechanical transmission that may be biased to apply a degree of pressure, ortension as it is more commonly called, between the two cutter blades. A certain amount of tension between the blades is necessary to produce proper cutting action.

Another object is to provide a mechanical transmission that is capable of a moderate universal joint action. As mentioned in my said prior patent, the respective movements of the armature and the movable cutter blade are such that the connection between the two cannot be rigid. The armature reciprocates in one plane. while the bearing surfaces of the two blades lie in another plane that is disposed at an angle to the plane of the armature. Due to the. tension between the blades, the movable blade reciprocates continuously in the plane of the bearing surfaces. Therefore the mechanical transmission must permit a moderate relative movement between the armature and the movable blade. The amount of movement, of course, is greatest when the movable blade reaches the ends of its reciprocating movement. This relative movement, I have found, is best provided for by universal joint action in the transmission.

Among transmissions heretofore used in electric hair clippers, the arrangement shown in Figs. 1-l of my said prior patent has been generally the most satisfactory. This arrangement comprises a non-yielding finger element projecting from the armature and received within a recess in the movable cutter blade. The finger element of this prior transmission is made of metal,

and, as the movable blade likewise is of metal, a loose metal-to-metal connection is provided.

The principal shortcomings of this prior transmission are that it is noisy in itself due to periodic changes in the loos seating relation between the finger and the recess (due to the aforesaid relative movement), and that it offers low resistance to the passage of sound vibrations in both directions. These characteristics result in an electric clipper that is undesirably noisy. A noisy clipper is unpleasant to adults, but, more objectionable, it unduly complicates hair cutting in the case of small children who are particularly sensitive to noise.

Briefly, there are numerous sources of noise in an electric hair clipper. There is, of course, the SO-cycle hum in the armature action. Further. th numerous teeth of the cutter blades in wiping across one another generate higher frequency vibrations that produce higher pitch sounds. The loose metal-to-metal contact between the non-yielding transmission finger and the movable blade gives rise to additional Sound vibrations because of the periodic seating and unseating of various portions of the finger. in the recess. These numerous vibrations, their harmonies and overtones travel through the metallic transmission into the body of the clipper where at least some of them tend to resonate, thereby. adding to the noise level.

Th transmission of my present invention, due to the use therein ofan element of resilient plastic material, such as nylon or the like, effectively damps out sound vibrations and prevents the travel of such vibrations from the cutter blades to the body of the clipper, and vice versa. A clipper using this new transmission is virtually noiseless.

The resilient plastic element of the transmission is in the form of a finger that is received within a recess in the movable cutter blade. Cooperating portions of both the finger and the recess are tapered, whereby. the pressure applied to the blade through the finger produces a wedg ing relationship. The resilience or elasticity of the plastic finger enables the finger to adjust itself as to size, if necessary, and thereafter to firmly grip the sides of the recess in such a manner that there is no relative movement between the finger. and the blade.

This firm gripping relationship produces two hi hly important results. Firstly, there is no rubbing between the finger and the sides of the recess, a factor that contributes to along life for the transmission. Secondly," the firm gripping 3 relationship insures that the aforesaid relative movement between the armature and the cutting blade will occur in a thin spring element that also forms a part of the transmission. The spring element, therefore, functions to provide a universal joint action.

Other objects, advantages and details of the invention will be apparent as the description'proceeds, reference being had to the accompanying drawing which illustrates one structural form of the invention. It is to be understood, of course, that in commercial applications of the invention various details might well vary somewhat from those here shown and described."

Inthedrawings: w

Fig. 1 is a top view of a portion of a clipper embodying my invention, the cover of the clipper casing being removed;

Fig. 2 is a side sectional view of the clipper portion shown in Fig. 1.;

Fig. 3 is a plan view'of the movable cutter blade illustrating a preferred form of finger receiving recess;

Fig. 4 is a top view of the nection of the invention;

. Fig. 5 is a sectional view on line 5-5 of Fig. 4; Fig. 6 is a sectional view on line 6-6 of Fig. 3, and

Fig. '7 is a sectional view on line l--7 of Fig. 3.

. Referring to Figs. 1 and 2 of the drawing, the electric clipper with which my invention is illus trated includes a casing I0 having a removable cover I I. An electromagnet I2 is mounted within casing I0 together with a cooperating core element I3.

A movable armature I5. more or less complementary in size to core element I3, also is mounted within casing I l. Armature I5 may be mounted as described in my co-pending application Serial No. 195,295, filed November 13, 1950, now abandoned.

A fixed cutter blade I! is mounted at one end of casing It the blade lying in a plane that makes an angle with the axis of armature I5. A movable cutter blade I8 makes a flat bearing engagement with fixed blade I 1. Both blades have usual cutting teeth I9.

The end of armature I5 adjacent the blades carries a spring strip '22 that extends toward movable blade I3. Spring strip 22, herein sometimes called a leaf spring, may be generally L-shaped as best shown in Fig; 4. One leg of the strip may conveniently be secured to armature I5 by the rivets that hold the armature laminations together. The other leg may have a plurality of holes 23 near the free end thereof for a purpose later to be mentioned. Spring strip 22 constitutes one element in my improved transmission.

The second and other element of the transmission is a short link of resilient plastic material such as nylon, polythylene, or the like that takes the form of a finger 25. Nylon is a particularly satisfactory material because of its property of toughness, as well as its resiliency: The resilience of importance to my invention manifests itself by way of a surface softness of the material, that is, the surface deforms somewhat so the finger is capable of adjusting itself slightly in size. Internal restoring forces in the deformed material produce the desired gripping action.

Finger may be afiixed to spring 22 in various ways but I have found that perhaps the most satisfactory way is to mold thelirrk to the spring. The previously mentioned holes 23 cooperate to transmission coninsure a good bond between the plastic and the spring.

Finger 25 is preferably rectangular in cross section as shown in Figs. 4 and 5. It extends beyond the end of spring 22 and terminates at free end 26 in a length that is inclined to the axis of the spring. The angle of inclination illustrated is approximately 45, an angle found satisfactory when the blades are oriented with respect to the armature and spring '22 as shown in Fig. 2. The width of free end 26 in the direction of movement of movable blade 18 is greater than one-fourth the width of blade I 8 in that direction.

. Free end 26 of finger 25 interfits with a por tion of movable blade I8. In the form of the invention illustrated, movable blade 3 has a.

centrally located recess 28 that receives free end 26 of the'finger.

It will be remembered that the transmission is adapted to exert a force on movable blade I8 so that there will be proper tensioning between blades.- For this reason, among others, the inclined length of finger 25 and the cooperating recess 28 are specially shaped. In the form of the invention illustrated, the four corners of the free end 25 of the finger are beveled in a tapering manner as shown at 3B in Figs. 4 and 5. Similarly, the corners of the recess 28 in movable blade I8 are beveled in a tapering manner as shown at 3I (Figs. 3, 6 and '7). These shapes produce a wedge-like relationship between finger 25 and recess 28 and insure that there is a firm seating relationship at least at the four corners.

When the clipper is assembled, armature I5 is mounted in the casing in such position that spring 22 of the transmission is tensioned, as mentioned in my said co-pending application Serial No. 195,295. The spring tension forces the free end of finger 25 firmly into recess 28. Because of the resilience of the plastic material, the finger adjust itself as to size and seats itself in the recess with a firm gripping action. With this arrangement, itwill be seen that finger 25 is connected in series in the mechanical transmission extendin between the armature and the movable cutter blade.

The comparatively large width of finger 25 at its free end 26 provides the leverage necessary to establish a twisting action in spring strip 22, and thus the desired yielding drive. and to prevent looseness at the wedge-like connection between finger 25 and blade 18.

It is of interest to mention that I experimented with resilient plastic material in general and nylon, polyethelene etc. in particular in this transmission because of the resilience characteristic thereof which is important to firm seating. This characteristic of the resilient plastic produced a finger that was greatly superior to a metal finger, or fingers of other materials I had used, from the standpoints of establishing a firm seating relation and of not becoming unseated during use.

However, in addition to the superior results obtained from resilient plastic in these regards, an extremely surprising and still different result was obtained. This result, heretofore mentioned, is that the plastic material effectively damps out sound vibrations, and theclippers utilizing this material in the transmission are substantially noiseless. This result was totally unexpected, particularly in the light of the use of nylon in phonograph needles, but its practical importance far surpasses that of the good seating characteristic also possessed by the resilient plastic.

The invention claimed herein is illustrated, at least in part, but not claimed in my said co-pending application Serial No. 195,295, filed November 13, 1950, now abandoned.

From the above description it is thought that the construction and advantages of my invention will be readily apparent to those skilled in the art. Various changes in detail may be made without departing from the spirit or losing the advantages of the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a vibrator type electric hair clipper, a power transmitting linkage connecting an armature to a movable cutter blade comprising a tensioned leaf spring carried by said armature and extending forwardly thereof toward said cutter blade, and a finger of resilient plastic material, said finger being generally rectangular in cross section and attached to the end of said spring with the axis of the free end of said finger being inclined to the axis of said spring, the free end corners of said finger being beveled in a tapering manner, a portion of the free end of said finger being received within a recess in said cutter blade, said recess being shaped to seat the beveled free end of said finger.

2. In a vibrator type electric hair clipper, a power transmitting linkage connecting an armature to a movable cutter blade comprising a tensioned spring strip mounted on said armature and extending toward said cutter blade, and a finger of resilient plastic material carried by said strip, the free end of said finger being received in and seated by a recess in said cutter blade.

3. In a vibrator type electric hair clipper, a

power transmitting linkage connecting an armature to a movable cutter blade comprising a tensioned leaf spring carried by said armature and extending forwardly thereof toward said cutter blade, and a finger of resilient plastic material generally rectangular in cross section attached to the end of said spring, the axis of the free end of said finger being inclined to the axis of said spring and generally normal to the surface of said cutter blade, the width of the free end of said finger in the direction of blade movement being greater than one-fourth the width of said blade in that direction, the free end corners of said finger being beveled in a tapering manner, a portion of the free end of said finger being received within a recess in said cutter blade, said recess being shaped to seat the beveled free end of said finger.

4. In a vibrator type electric hair clipper, a power transmitting linkage connecting an armature to a movable cutter blade comprising a tensioned spring strip mounted on said armature and extending toward said cutter blade, and a finger of resilient plastic material carried by said strip, the free end of said finger being received in and seated by a recess in said cutter blade, the width of said free end in the direction of blade movement being greater than one-fourth the width of said blade in that direction.

LEO J. WAI-IL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,013,229 Andis Sept. 3, 1935 2,265,880 Wahl Dec. 9, 1941

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