Abstract:
In accordance with the present invention, a plurality of circular shaped, slotted foils or cutting heads are simultaneously produced using electroforming production techniques followed by passage of each slotted foil or cutting head through either a single die or a progressive die to form the slotted foil or cutting head into the desired three-dimensional circular or annular shape required for a rotary shaver. Furthermore, in order to produce a slotted foil or cutting head which is extremely thin, to attain a close, comfortable shave, each of the fully formed slotted foils or cutting heads is passed through an insert molding operation, wherein a supporting rim or ring is affixed to the outer edge of the slotted foil or cutting head, thereby imparting rigidity or stiffness thereto. As a result, slotted foils or cutting head are able to be manufactured at a substantially reduced cost, and with precisely desired and controlled configurations.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates to electric dry shavers and more particularly to improved manufacturing methods for producing cutting foils or heads for rotary shavers.  
         BACKGROUND ART  
         [0002]    Over the last several years, both men and women have been increasingly drawn to the advantages provides by electric dry shavers. In general, the consuming public has found that the use of razors or other systems is extremely inconvenient for removing or shaving short hair or stubble, as commonly found in men&#39;s beards and on women&#39;s legs. In addition, with the ever-increasing time constraints and commitments individuals typically encounter, a fast and effective shaving system is most desirable.  
           [0003]    The discomfort, as well as the time consumed in using shaving cream, soaps, or gels in order to provide a medium for which a razor can be used, requires more time and inconvenience than most individuals are willing or capable of allowing. Furthermore, the cost of maintaining a sufficient supply of these products creates an additional burden. Consequently, electric dry shavers have become increasingly popular, as well as battery-operated electric dry shavers which can withstand exposure to moisture, thereby enabling individuals to simultaneously shower, as well as shave either beards or legs.  
           [0004]    As the popularity of electric dry shaves increased, various product designs and alternate constructions proliferated, in an attempt to improve and enhance the comfort and cutting efficiency of such shavers. However, in spite of these product changes, difficulties have continued to exist in providing optimum results with optimum comfort.  
           [0005]    Two principal configurations have been found to be extremely efficacious in achieving high quality shaving results, as well as being extremely comfortable to use. These configurations comprise the various models of electric dry shavers incorporating a movable cutting blade which cooperates with a thin, flexible mesh screen or apertured foil and electric dry shavers employing a plurality of rotating circular cutting blades, each associated with a separate, circular shaped foil or slotted cutting head.  
           [0006]    In operation, the cutting blades rapidly and continuously move against one side of the apertured foil or slotted cutting head, causing the cutting blades to repeatedly cross the plurality of apertures or slots and provide a virtually continuous cutting action at each aperture or slot. Then, by sliding or guiding the other side of the apertured foil or slotting cutting head over the skin surface to be shaven, the individual hair shafts enter the holes or slots formed in the foil and are cut by the movement of the cutting blades.  
           [0007]    Although these dry shaving cutting systems have proven to be extremely effective, as compared to other dry shaving products, one area of difficulty does exist which prior art systems have been unable to satisfactorily resolve. This area is the inability of prior art electric dry shavers incorporating apertured foils to effectively cut longer hair or whisker shanks or fibers. Longer hair shanks or fibers tend to be less rigid and, consequently, do not enter the apertures of the foil member as the dry shaver is moved over the skin surface. Instead of entering the apertures, the fibers tend to bend and be flexed away from the foil, thereby remaining uncut, leaving an unsatisfactory result.  
           [0008]    In order to resolve this deficiency, the shavers incorporating a plurality of rotating, circular shaped cutting blades which cooperate with separate, circular shaped or annular foils or cutting heads have been developed, with each foil or cutting head incorporating radially extending slots formed therein. By incorporating elongated slots in the cutting heads associated with each circular shaped cutting blade, longer hair fibers are capable of being cut efficiently.  
           [0009]    Even though the longer hair fiber drawback of foils shavers has been substantially resolved with this rotary shaver construction, shavers incorporating rotary or circular shaped shaving elements are generally incapable of providing shaving results as close as conventional flat foil shavers. Typically, this is due to the thickness of the material which is required to produce circular cutting foils or heads. In addition, another unresolved difficulty which continues to exist with all shavers incorporating rotary or circular shaped cutting elements is the substantial expense incurred in manufacturing the circular shaped, slotted foils or cutting heads.  
           [0010]    In general, in manufacturing slotted foils or cutting heads for rotary drive shavers, each cutting element must be stamped in the desired configuration from a metal sheet and then machined or ground in a manner which will provide the desired slotted configuration as well as a sharp cutting edge. Due to the substantial equipment investment, manual labor, and time effort required to produce these slotted foils or cutting heads, each cutting head or slotted foil results in a large financial investment which is incurred in its production. The investment or cost must be incorporated into the overall price for the rotary shaving system.  
           [0011]    Consequently, it is a principal object of the present invention to provide an improved rotary drive shaver incorporating circular shaped, slotted foils or cutting heads which are capable of being mass produced at a substantial reduced cost.  
           [0012]    Another object or the present mention is to provide an improved rotary drive shaver construction having the characteristic features described above which provides a smooth, comfortable, close shave for both long hair fibers and short hair fibers.  
           [0013]    Another object or the present mention is to provide an improved rotary drive shaver construction having the characteristic features described above wherein the slotted foils or cutting heads are manufactured in a substantially final form, ready for assembly in the rotary drive shaver with minimum manual effort being required.  
           [0014]    Other and more specific objects will in part be obvious and will in part appear hereinafter.  
         SUMMARY OF THE INVENTION  
         [0015]    By employing the present invention, all of the difficulties and drawbacks encountered in prior art constructions have been eliminated and a rotary drive shaver is obtained which is capable of being manufactured with the slotted foils or cutting heads being manufactured at a substantially reduced cost, and with precisely desired and controlled configurations. As a result, by employing the present invention, the slotted foils or cutting head employed in the rotary drive shaver provide improved cutting action, achieving a substantially enhanced close and comfortable shave.  
           [0016]    In accordance with the present invention, a plurality of circular shaped, slotted foils or cutting heads are simultaneously produced using electroforming production techniques typically employed for producing or manufacturing substantially flat products. In the conventional electroforming process, an image is created having the desired geometry for the product being produced. This image is transferred onto a metal plate, and the metal plate is treated with a photosensitive coating and then exposed to a photo masking process. In the present invention, a plurality of images are formed on the single enlarged metal plate in order to produce a plurality of separate and independent circular shaped slotted foils or cutting heads in a single operation.  
           [0017]    Once the plurality of images have been formed on the metal plate and the masking process is completed, current is applied to the metal plate and the metal plate is exposed to a plurality of submersion steps in order to form the desired product in a precisely desired, detailed, and controlled configuration and thickness. Although a substantially flat, two-dimensional product is usually produced, this technique may also be employed to produce a three-dimensional product.  
           [0018]    Once the plurality of slotted foils or cutting heads have been produced in a substantially flat configuration by the electroforming process, each of the slotted foils or cutting heads are cut from the metal plate and passed through either a single die or a progressive die to form the slotted foil or cutting head into the desired three-dimensional circular or annular shape required for a rotary shaver.  
           [0019]    Due to the desire to produce a slotted foil or cutting head which is extremely thin, in order to attain a close, comfortable shave, each of the fully formed slotted foils or cutting heads is passed through an insert molding operation, wherein a supporting rim or ring is affixed to the outer edge of the slotted foil or cutting head. In this way, the desired rigidity or stiffness is imparted to the resulting product.  
           [0020]    In order to complete the entire manufacturing process and attain a final, completed, circular shaped or annular slotted foil or cutting head, a second insert molding step is employed for securing a center hub or support plate to the slotted foil or cutting head. Typically, the center hub or support plate is employed to impart added stiffness to the final product, as well as to provide an outside surface for retaining printed indicia and an inside receiving zone for cooperating alignment with the cutting blades associated therewith.  
           [0021]    As is evident from the foregoing, the present invention achieves a fully produced, ready to use, circular shaped or annular slotted foil or cutting head in an extremely efficient, low cost manner. Furthermore, by enabling the slotted foil or cutting head to be produced with a precisely controlled thickness and a precisely controlled slot configuration, an extremely effective, efficient close and comfortable shaving result is achieved.  
           [0022]    The invention accordingly comprises the several steps and the relation of one or more such steps with respect to each of the others, and the article produced possessing the features, properties, and relation of elements which are exemplified in the following detailed disclosure, with the scope of the invention and being indicated in the claims.  
       
    
    
     THE DRAWINGS  
       [0023]    For a fuller understanding of the nature and the object of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:  
         [0024]    [0024]FIG. 1 is a perspective view of a flat, circular shaped, slotted foil or cutting head produced by the electroforming process employed in the present invention;  
         [0025]    [0025]FIG. 2 is a top plan view of the flat, circular shaped, slotted foil or cutting head of FIG. 1;  
         [0026]    [0026]FIG. 3 is a substantially enlarged, top view of a portion “A” of the circular shaped, slotted foil or cutting head of FIG. 2;  
         [0027]    [0027]FIG. 4 is a perspective view of the circular shaped, slotted foil or cutting head of the present invention after passage through a forming die;  
         [0028]    [0028]FIG. 5 is a top plan view of the circular shaped, slotted foil or cutting head of FIG. 4;  
         [0029]    [0029]FIG. 6 is a side elevation view, partially in cross-section, of the circular shaped, slotted foil or cutting head of FIG. 5;  
         [0030]    [0030]FIG. 7 is a perspective view, partially in cross-section, depicting a circular shaped slotted foil or cutting head of the present invention incorporating the outer stiffening rim or ring;  
         [0031]    [0031]FIG. 8 is a side elevation view of the circular shaped, slotted foil or cutting head of FIG. 7;  
         [0032]    [0032]FIG. 9 is a perspective view, partially in cross-section, depicting a fully assembled circular shaped slotted foil or cutting head of the present invention;  
         [0033]    [0033]FIG. 10 is a side elevation view of the circular shaped slotted foil or cutting head of FIG. 9; and  
         [0034]    [0034]FIG. 11 is a plan view of a sheet of material incorporating a plurality of separate and independent foil members formed thereon.  
     
    
     DETAILED DESCRIPTION  
       [0035]    By referring to FIGS.  1 - 11 , along with the following detailed disclosure, the construction, production, and operation of the slotted foil, cutting head, or shear plate  20  of the present invention can best be understood. As detailed herein, the preferred embodiment of slotted foil or cutting head/shear plate  20  of the present invention, as well as its preferred method of manufacture, is fully detailed herein and exemplified in FIGS.  1 - 11 . However, this construction and method of production can be altered without departing from the scope of this invention. Consequently, it is to be understood that the following detailed disclosure is provided for exemplary purposes, and is not intended as a limitation of the scope of the present invention.  
         [0036]    In FIGS.  1 - 3 , slotted foil or cutting head/shear plate  20  is depicted as substantially flat plate  21 , after production from an electroforming process. In this configuration, which represents its first intermediate configuration of its formation process, flat plate  21  comprises a generally circular shape incorporating two circular shaped, concentric zones or portions, depicted as inside zone  22  and outer zone  23 , and an outer terminating edge  25 .  
         [0037]    As shown, inside zone  22  comprises a substantially flat, smooth surface and a central aperture  24 . As depicted, the inside zone  22  extends from central aperture  24  to the boundary with outer zone  23 . As is more fully detailed below, central aperture  24  may comprise any desired shape or configuration. However, in the preferred construction, aperture  24  is constructed for receiving and cooperatingly engaging with a central, reinforcing hub.  
         [0038]    One principal aspect of the present invention is the construction of outer zone  23  of slotted foil or cutting head/shear plate  20 . By employing the present invention, outer zone  23  is constructed in a substantially completed form, without requiring expensive and time-consuming machining operations. In this regard, outer zone  23  is directly formed by an electroforming process to incorporate a plurality of elongated slots  26  and  27  formed throughout zone  23 .  
         [0039]    By employing the present invention, slots  26  and  27  are constructed with any desired size, shape, and configuration. In addition, slots  27  are capable of being constructed with configurations which were previously impossible, due to the inability of the prior art methods to machine the metal material into such configuration. Examples of such complex slot configurations include sinusoidal shapes, both regular and irregular, as well as other complex shapes incorporating numerous angles and turns. Although the Figures depict generally conventional, longitudinally extending slots  26  and  27 , all complex shapes and configurations are within the scope of this invention.  
         [0040]    In the preferred construction of outside zone  23  of slotted foil or cutting head/shear plate  20 , a plurality of elongated slots  26  and  27  are formed therein. As discussed, although any desired size, shape, and configuration can be employed for slots  26  and  27 , one preferred embodiment is depicted in FIGS.  1 - 3 . In this embodiment, elongated slots  26  and  27  are formed in substantially flat plate  21  in a generally aligned, radially extending configuration, forming two partially overlapping circular arrays.  
         [0041]    As depicted, radially extending slots  26  are formed in substantially flat plate  21  positioned in juxtaposed, spaced, cooperating relationship with each other, forming a first circular array, with one edge of each elongated slot  26  extending from the boundary with inside zone  22 . In addition, radially extending slots  27  are formed in substantially flat plate  21  positioned in juxtaposed, spaced, cooperating relationship with each other, forming a second circular array, with one edge of each elongated slot  27  being formed inwardly of terminating edge  25  of substantially flat plate  21 . Furthermore, radially extending slots  26  and  27  are preferably constructed with a portion of each slot of each of the two arrays positioned in a partially overlapping configuration.  
         [0042]    In addition, elongated, radially extending slots  26  and  27  are each constructed with radially extending side edges  28  and  29 , positioned in juxtaposed, spaced, relationship to each other. This construction is best seen in FIG. 3. By controlling the spaced distance between side edges  28  and  29  of each radially extending slot  26  and  27 , the precisely desired control over the cutting action provided by slotted foil or cutting head/shear plate  20  is attained. Although any desired spaced distance can be employed, the preferred embodiment comprises a spacing between side edges  28  and  29  which ranges between about 0.010 and 0.012 inches.  
         [0043]    In the preferred embodiment of the present invention, slotted foil or cutting head/shear plate  20  also incorporates a plurality of narrow slits  34  each being formed in outside zone  23  of flat plate  21 , extending from terminating edge  25  to the edge of elongated slot  27  which is adjacent terminating edge  25 . By incorporating the plurality of narrow slits  34  in substantially flat plate  21 , the formation of slotted foil or cutting head/shear plate  20 , as detailed below, is capable of being achieved with greater ease.  
         [0044]    A further element incorporated into substantially flat plate  21  of slotted foil or cutting head/shear plate  20  are a plurality of small holes or apertures  35  formed in flat plate  21  directly adjacent terminating edge  25 . As depicted in the Figures, apertures  35  are preferably formed directly adjacent each other, establishing a substantially circular array of apertures  35  positioned directly adjacent terminating edge  25 . In addition, as depicted, elongated narrow slits  34  are positioned, radially extending between apertures  35 . As is fully detailed below, apertures  35  are employed in a subsequent formation step of the present invention wherein a stiffening ring is affixed to terminating edge  25 .  
         [0045]    In FIGS. 1 and 2, slotted foil or cutting head/shear plate  20  of the present invention is depicted in its fully configured form as a single component. However, in the preferred construction, as fully detailed below, the process of the present invention enables a plurality of slotted foils or cutting heads/shear plates  20  or flat plates  21  to be simultaneously produced. In this way, substantial cost savings are realized with numerous slotted foils or cutting heads/shear plates  20  or flat plates  21  being produced in a single operation.  
         [0046]    In the preferred process, an image is created which represents the desired geometry and configuration for slotted foil or cutting head/shear plate  20 . In developing this image, the precisely desired size, shape, and configuration for elongated slots  26  and  27  is developed, along with the configuration for inside zone  22  and aperture  24 . Once this final geometry and image has been finalized, the image is transferred onto a metal plate. The metal plate is treated with a photosensitive coating and then exposed to an ultraviolet photo masking process. This process causes the metal sheet to function as a photographic negative, at which point the metal plate is rinsed to expose the desired geometry representing the precisely desired configuration being sought.  
         [0047]    In a typical operation, as shown in FIG. 11, the metal plate is produced with a plurality of identical, separate and distinct images formed thereon, with each image representing one slotted foil or cutting head/shear plate  20 . Once the construction of the metal plate has been completed, current is passed through the metal plate while the plate is submerged in an electroforming bath.  
         [0048]    In the electroforming bath, metal ions are attracted to specific sites of each image formed on the metal plate, causing metal ions to be deposited at the specific sites or locations. By submerging the metal plate in the electroforming bath for a predetermine time period, metal particles accumulate, effectively producing the precisely desired slotted foil or cutting head/shear plate with the precisely desired configuration originally formed on the metal plate.  
         [0049]    In addition, by precisely controlling the length of time of the submersion to which the metal plate is subjected, a precisely controlled thickness is achieved for slotted foil or cutting head/shear plate  20 . As a result, the electroforming process employed in the present invention achieves all of the attributes desired for an effective, efficient, and close shaving slotted foil or cutting head/shear plate.  
         [0050]    By employing the teaching of the present invention, slotted foil or cutting head/shear plate  20  can be formed with any thickness desired. However, it has been found that the preferred thickness of slotted foil or cutting head/shear plate  20  ranges between about 0.0015 and 0.0020 inches.  
         [0051]    Once the plurality of slotted foils or cutting heads/shear plates have been produced on the metal foil to the precisely desired specifications, each slotted foil or cutting head/shear plate  20  is removed from the metal foil by die cutting or other appropriate methods. Once removed, slotted foil or cutting head/shear plate  20  is in the configuration of substantially flat plate  21 , as depicted in FIGS. 1 and 2.  
         [0052]    In the next process step of the present invention, substantially flat plate  21  is transferred to a single forming die or a progressive forming die wherein substantially flat plate  21  is formed into fully shaped cutting member  30 , depicted in FIGS. 4, 5, and  6 . During this forming process, outer zone  23  is bent to form two, co-axial, circular shaped arcs or curved edges  48  and  49 , defining distinct sections consisting of a substantially flat top section  32 , depending, peripherally surrounding flange section  31 , and inside ledge or wall section  33 . As depicted, flange section  31  extends substantially perpendicularly from the terminating end of top section  32  at curved edge  48 , while ledge or wall section  33  extends substantially perpendicular from top section  32  at curved edge  49 . Furthermore, as a result of this construction, slots  27  extend about curved edge  48 , defining open zones for easy entry of hair fibers therein along with top section  32  and flange section  31 .  
         [0053]    Similarly, slot  26  extends about curved edge  49 , defining open zones for easy entry of the hair fibers therein along both top section  32  and wall section  33 . In this way, entry zone for slots  26  and  27  are provided throughout outside zone  23  of cutting member  30 , thereby assuring that the desired cutting action is attained.  
         [0054]    As is evident from the foregoing detailed disclosure, as well as best seen in FIG. 6, the die formation step employed in the present invention creates cutting member  30  with a substantially flat, smooth surface forming inside zone  22  and positioned in a first plane, while substantially flat top section  32  is formed in a second plane. In this resulting configuration, the second plane, within which top section  32  is contained, is in juxtaposed, spaced, substantially parallel relationship to the first plane, while also being spaced above the first plane. In this way, the precisely desired overall configuration for cutting member  30  is achieved.  
         [0055]    The next step in the construction of slotted foil or cutting head/shear plate  20  of the present invention is the molding of stiffening ring  36  directly to outer, flange section  31  of outer zone  23 . Although various alternate methods can be employed, it has been found that the use of insert molding equipment is preferred. Using insert molding equipment, cutting member  30  is positioned in the mold cavity thereof, and the cavity is closed to enable plastic material to be injected into the mold cavity in peripherally surrounding, secure engagement with a portion of flange section  31 . Once completed, the plastic is allowed to cool and the resulting product is ejected from the molding equipment.  
         [0056]    In order to assure secure, affixed interengagement between plastic ring  36  and flange section  31 , flange section  31  is preferably formed with a plurality of holes or apertures  35  formed along the terminating end thereof. In this way, the plastic material is able to pass through apertures  35  and provide secure affixation thereof to flange section  31 .  
         [0057]    By securely affixing plastic ring  36  directly to flange section  31 , added strength and rigidity is imparted to slotted foil or cutting head/shear plate  20 . In addition, plastic ring  36  also establishes the final configuration desired for enabling slotted foil or cutting head/shear plate  20  to be easily handled, as well as mounted in position in cooperating relationship with the cutting blades of a rotary shaver.  
         [0058]    In accordance with a present invention, the final step in completing the formation of slotted foil or cutting head/shear plate  20  is the affixation of center hub  40  to cutting member  30 . This is most easily achieved by employing a second insert molding machine or simultaneously affixing center hub  40  to cutting member  30  along with the affixation of plastic ring  36 .  
         [0059]    As depicted, center hub  40  is securely affixed to cutting member  30  by employing central aperture  24  of inside zone  22 . In this preferred configuration, central hub  40  comprises an enlarged, plate portion  41  which is formed on the top of surface  26 , and a receiving cavity  42  formed on the bottom surface thereof, positioned inside of slotted foil or cutting head/shear plate  20 . In the preferred construction, receiving cavity  42  is employed for providing co-operative, aligned, interengagement with the cutting blade of the rotary shaver.  
         [0060]    In this way, the desired cutting interengagement between the cutting blade and aperture foil or cutting head/shear plate  20  is provided. In addition, plate portion  41  provides added strength and rigidity to slotted foil or cutting head/shear plate  20 , while providing an enlarged surface upon which any desired indicia can be displayed.  
         [0061]    It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently obtained and, since certain changes may be made in carrying out the above method and in the article set forth without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.  
         [0062]    It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.  
         [0063]    Having described my invention, what I claim as new and desired to secure by Letters Patent is: