Abstract:
A method of manufacturing a handle for a personal grooming device includes forming a substrate portion of a first material. The substrate portion has first and second walls forming a channel extending along a long axis of the substrate portion. An insert member is formed separate from the substrate portion and disposed within the channel. A grip portion of a second material is formed on the substrate portion. The second material substantially encases the insert member.

Description:
REFERENCE TO RELATED APPLICATION 
     This application is a division of U.S. application Ser. No. 12/349,553, filed Jan. 7, 2009, now U.S. Pat. No. 8,435,433. 
    
    
     FIELD OF THE INVENTION 
     This application relates to handles for personal grooming devices and methods of manufacturing the same. 
     BACKGROUND OF THE INVENTION 
     Handles for personal grooming devices are well known. Some device handles are formed by a “two-color” injection molding process combining a relatively rigid material with a relatively flexible material. The combination of rigid and flexible materials may improve the ergonomics associated with such handles and provide an improved shaving experience over single material handles. Some personal grooming device handles have relatively large cross sections for improved handling and comfort while being used. Larger cross sections may require longer cycle times during molding to completely fill out the mold cavities and avoiding sinks in the handle material during cooling. In one example, a rigid inner core is molded in a first mold cavity and a second layer of rigid material is molded over the inner core in a second mold cavity. A flexible grip portion is molded onto the second layer in a third cavity. All three cavities are contained in the same mold. The parts are moved from cavity to cavity by in-mold automation. In another example, a device handle has a rigid first molded portion, a flexible second molded portion, and a battery-operated device that is at least partially encased between the first and second molded portions. 
     Some personal grooming devices are disposable in that they are meant to be discarded when they no longer provide an adequate grooming experience. Disposable personal grooming devices must strike a balance between its price and the quality of the grooming experience. Lowering manufacturing costs of disposable personal grooming devices without sacrificing features that contribute to the quality of the grooming experience represents an unmet need in the marketplace. While disposable personal grooming devices are more price sensitive than so-called “system” devices (e.g., a safety razor shaving system having a reusable razor handle and detachable, disposable blade units), such system devices may also benefit from lower manufacturing costs. 
     SUMMARY OF THE INVENTION 
     The invention relates to handles for personal grooming devices and methods of manufacturing the same. 
     In one aspect, the invention features, in general, a method of manufacturing a handle for a personal grooming device including forming a substrate portion of a first material. The substrate portion has first and second walls forming a channel extending along a long axis of the substrate portion. An insert member is formed separate from the substrate portion and disposed within the channel. A grip portion of a second material is formed on the substrate portion. The second material substantially encases the insert member. 
     In another aspect, the invention features, in general, a handle for a personal grooming device. The handle has a substrate member comprising a channel, an insert member disposed within the channel, and a grip portion disposed on the substrate member and substantially encasing the insert member. A tower portion extends through an exterior surface of the grip portion. 
     Certain implementations of the invention may include one or more of the following features. The substrate portion has a rib portion transversely extending between the first and second walls. The insert member has a slot sized to receive the rib portion and disposing the insert member within the channel includes inserting the rib portion into the slot. The insert member has a hook portion. Disposing includes hooking the hook portion onto the substrate portion. The insert member has a finger portion projecting from an upper surface. Disposing the insert member within the channel includes clamping the finger portion to fix its position within the channel during forming of the grip portion. The substrate portion includes a tower portion disposed between the first and second walls and extending from the joined portion. The tower portion has a top surface. The insert member includes an opening sized to accommodate the tower portion and disposing the insert member within the channel includes inserting tower into the opening. The top surface is at least substantially flush with an exterior surface of the grip portion. The grip portion completely encases the insert member. The substrate portion is formed of a rigid material. The substrate portion is formed of a polyethylene plastic. The grip portion is formed of a thermoplastic elastomer. The substrate portion includes a blade unit connecting portion. The blade unit connecting portion comprises tab member forming a first snap fit recess in a top surface thereof and forming a second snap fit recess in a bottom surface thereof. 
     Features of the present invention may have one or more of the following advantages. The cross-sections of the three component parts allow for faster cycle times and, thus lower manufacturing costs over more commonly known two part handles of similar size and ergonomics. The parts may be assembled by hand, avoiding expensive handling and assembly equipment, thereby further reducing the manufacturing costs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of an exemplary safety razor of the present invention; 
         FIG. 2  is an exploded isometric view of an exemplary handle and insert of the present invention; 
         FIG. 3  is an isometric view of a second exemplary insert of the present invention; 
         FIG. 4  is an isometric view of a third exemplary insert of the present invention; 
         FIG. 5  is section view of a mold cavity forming the handle of  FIG. 2 ; 
         FIG. 6  is section view of a mold cavity for forming the grip of  FIG. 1 ; 
         FIG. 7  is section view of the safety razor handle of  FIG. 1 ; and 
         FIG. 8  is an isometric view of an exemplary toothbrush of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 and 2 , in some examples, safety razor  10  includes a handle  12  pivotally joined to a blade unit  14  by a connecting member  16 . Blade unit  14  includes a plastic housing  17  and three blades  18  each with an elongated sharp cutting edge between a guard at the front of the housing and a cap with a lubricating strip at the rear of the housing and retained by clips  20 . In other examples, two, four, five, or more blades could be included. In one example, blade unit  14  is similar to that of the Mach III razor, sold by The Gillette Company. 
     Handle  12  has a core portion  22  at least partially enclosed by a grip portion  24 . Generally, core portion  22  may have a substantially consistent cross-section for good plastic flow, filling, and cooling during molding, as is understood in the art. In some examples, core portion  22  has a channel  26  extending along its length and formed by walls  28  and  30 . One or more ribs  32  (shown in broken line in  FIG. 2 ) may extend between walls  28  and  30  to provide rigidity and to interact with other elements as described below. In one example, a tower portion  34  projects upwardly from a bottom surface  35  ( FIGS. 5-7 ) of the channel  26  to a surface  36  for displaying information to a consumer. An attachment member  38  may be disposed at a distal end  40  of core portion  22  and form openings  42  for use with the blade unit  14  and/or connecting member  16 , such as for snap fit or blade unit biasing elements. 
     Grip portion  24  forms the body portion  44  of handle  12  by filling channel  26  and at least partially enclosing exterior  45  of core portion  22 . Grip portion  24  may form gripping elements to enhance a user&#39;s shaving experience, such as bands  46  or other elements, such as bumps, ridges, ribs, and fins, for example. Body portion  44  should be wide enough to be comfortably held by a range of adult hands. In one example, body portion  44  has a width W of about 0.65 inches, while in other examples, the width W may be about 0.40, 0.45, 0.50, 0.55, 0.60, 0.70, 0.75 or 0.80 inches. Those skilled in the art will understand that plastic parts with thick cross sections take longer to mold and require larger molding presses to manufacture, increasing the cost of such parts. 
     Referring to  FIGS. 2 and 5 , core member  48  is disposed in channel  26 , thereby reducing the cross-sectional area thereof into which grip portion  24  will be formed. Adding core member  48  improves manufacturability by decreasing molding cycle times of grip portion  24 , as will be understood by those skilled in the art. In one example, the thickness T of wall  50  is about 0.05 inches while in other examples, the thickness T may be about 0.03, 0.04, 0.06, 0.07, or 0.08 inches. In still other examples, insert member  48  could contact walls  28  and  30 , preventing grip portion  24  from completely enclosing core member  48 . 
     Insert member  48  forms opening  52  sized to receive tower portion  34  and slots  54  sized to receive ribs  32 . An interference fit between these features of insert member  48  and core portion  22  keeps the two assembled until grip portion  24  is formed about them. In other examples, insert member  48  includes a post  56  ( FIG. 3 ) projecting upwardly from an upper surface  60  that may be used to hold the position of insert member  48  in the desired relation to core portion  22  while grip portion  24  is formed. In still other examples, snap arm  62  ( FIG. 4 ) may downwardly project from insert member  48  for snapping into features of core portion  22  (not shown). 
     In some examples, core portion  22  and insert member  48  are formed of a relatively rigid plastic, such as HP741T polypropylene, available from Basell Polyolefin Corp. (Hoofddorp, The Netherlands). Grip portion  24  is formed of a relatively flexible thermoplastic elastomer, such as LC316-110A available from GLS Polymers Pvt. Ltd (Bangalore, India). However, any suitable combination of materials may be used, including different materials for core portion  22  and insert member  48 . 
     Referring to  FIGS. 5-7 , a method of manufacturing handle  12  is shown. Core portion  22  is formed in and then removed from mold  70 . In some examples, insert member  48  is formed separately in another mold, which avoids having to separate the parts if they were made in the same mold, while in other examples, core portion  22  may be formed in mold  70 . Core portion  22  and insert member  48  are assembled into assembly  74  by passing tower portion  34  into opening  52  and pressing ribs  32  into slots  54 . In some examples, assembly  74  is manually assembled to keep capital equipment costs low, while in other examples, assembly  74  may be assembled by automated equipment. Assembly  74  is placed in mold  76  and grip portion  24  is injection molded around it, substantially encasing insert member  48 . In some examples, grip portion  24  may completely encase insert member  48 . 
     Alternative embodiments are within the scope of the claims. 
     For example, referring to  FIG. 8 , toothbrush  60  has a handle portion  62  and a head portion  64  having bristles  66  for brushing teeth. Substrate portion  68  and an insert member (not shown) are at least partially enclosed by a grip portion  70 . Head portion  64  may be formed from substrate portion  68 , grip portion  70 , or some combination thereof. 
     The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.” 
     All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention. To the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern. 
     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.