Abstract:
A method of constructing a double-walled blow-molded article with a hinged handle is performed on an article comprising a receiving member and a pinned member. The receiving member is a double-walled blow-molded thermoplastic component having an outer wall, an inner wall, and an open-ended receptacle. The open ended receptacle is defined by an arcuate pocket positioned opposite the open end, a stationary wall extending from the pocket and facing generally in a first direction, and a deflecting wall positioned opposite the stationary wall and facing generally in a second direction opposite the first direction. The pinned member includes a cylindrical pin. The method comprises as a first step passing the cylindrical pin through the open end of the receptacle and into contact with the pocket. Passage of the pin is performed such that the deflecting wall deflects away from the stationary wall as the pin travels between the deflecting wall and said stationary wall, and such that the deflecting wall recovers toward the stationary wall as the pin contacts the pocket. This passing step is carried out as the receiving member remains at an elevated temperature at which the thermoplastic comprising the receiving member has a first elastic modulus.

Description:
This application is a divisional application of U.S. patent application Ser. No. 09/013,243, filed Jan. 26, 1998, now U.S. Pat. No. 6,152,317. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to hinged articles, and relates more specifically to blow-molded hinged articles. 
     BACKGROUND OF THE INVENTION 
     Blow molding is a well-known fabrication method for thermoplastic components. The process generally involves the molding of a hollow tube, or “parison,” of molten thermoplastic that is lowered from an overhanging extrusion head to a position between halves of a reciprocating mold. As the mold halves close, air or some other gas is injected into the parison; the increase in air pressure within the parison caused by such injection forces its walls into the contours of the cavities of the mold halves and thus forms the parison into a desired molded shape. The resulting component has molded walls that surround a hollow chamber. Blow molding has proven to be particularly popular for the production of large parts that would require unduly large molding injection molding machines. 
     One type of blow molding that has been used successfully for large components that require structural rigidity is the so-called “double-walled” blow molding process. In this process, mold halves are most often designed as distinct core and cavity halves (rather than as two cavities, as would be the case for blow-molded bottles or other containers). The core portion of the core mold half extends within the cavity as the mold halves close. In addition, the mold halves for double-walled components are configured so that the molded components have “full-perimeter flash”; i.e., after molding the component has excess material, or “flash”, around the perimeter defined by mating surfaces of the mold halves. This contrasts with single-walled components, in which the parison is inflated entirely within closed mold cavities, and the molded component typically has flash only on its top and bottom portions. Blow-molded components have distinct inner and outer walls that surround a hollow space, with the inner wall having been formed by the core and the outer wall having been formed by the cavity, and with the inner and outer walls being separated by the weld line remaining after the flash is removed. In a typical double-walled component the inner and outer walls are positioned proximate to one another and can have “pinched-off” areas, in which the inner and outer walls are contiguous. 
     One distinct advantage provided by double-walled blow-molded components is the capability for adjacent regions of the inner and outer walls to differ significantly in their localized contour. For example, a region of the outer wall may have a relatively flat profile, while the adjacent region of the inner wall can contain numerous projections, recesses, and the like, with the profile of either localized region failing to impact significantly the appearance or structural integrity of the other. Such differences in localized inner and outer wall contour are less likely to be successfully achieved in injection-molded components because the inclusion of substantial detail in the inner wall can have a deleterious effect on the dimensional stability, appearance, and even strength of the outer wall. Another performance advantage conveyed by double-walled components stems from the formation of the hollow chamber within the inner and outer walls, as it can provide an air cushion that protects items contacting the inner wall. 
     For these reasons, double-walled components have proven to be particularly popular for protective containers and carrying cases. Detailed contour that mates with, matches, supports, or captures portions of an item to be carried within the carrying case can be included in the inner wall of the double-walled component even as the outer wall has a generally flat, appearance-sensitive surface. Further, the air cushion between the inner and outer walls helps to protect the item. Thus, the container has the detail and structure necessary to support, transport and protect the item and also provides the desired aesthetic appeal, and does so without the manufacturer having to produce two separate inner wall and outer wall parts. 
     Many carrying cases have handles to enable the user to more easily pick up, carry, and otherwise manipulate the carrying cases. Some double-walled blow-molded carrying cases include handles that are molded integrally with the body of the case. One example of such a carrying case is illustrated in U.S. Pat. No. 5,361,456 to Newby. The carrying case illustrated therein has a fixed handle that extends away from the body of the carrying case. The handle is formed in each half of the carrying case during the blow molding process by sections of the mold halves that pinch off a portion of the parison that is positioned inward from the outer perimeter of the mold. The pinched-off portion is removed from the molded part to form an opening. The opening and the remaining perimeter portion of the part form the handle for the carrying case. 
     This design has certain shortcomings, the most prevalent of which is the fact that the handle permanently extends away from the internal storage cavity defined by the halves of the carrying case. In this configuration, the handle cannot be folded to a less extended position for easier storage. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a double-walled blow molded carrying case with a handle that can be folded for storage. 
     It is also an object of the present invention to provide a process for producing such a carrying case. 
     These and other objects are satisfied by the present invention, which is directed to a method of constructing a double-walled blow-molded article with a hinged handle. The method is performed on an article comprising a receiving member and a pinned member. The receiving member is a double-walled blow-molded thermoplastic component having an outer wall, an inner wall, and an open-ended receptacle. The open ended receptacle is defined by an arcuate pocket positioned opposite the open end, a stationary wall extending from the pocket and facing generally in a first direction, and a deflecting wall positioned opposite the stationary wall and facing generally in a second direction opposite the first direction. The pinned member includes a cylindrical pin. The method comprises as a first step passing the cylindrical pin through the open end of the receptacle and into contact with the pocket. Passage of the pin is performed such that the deflecting wall deflects away from the stationary wall as the pin travels between the deflecting wall and said stationary wall, and such that the deflecting wall recovers toward the stationary wall as the pin contacts the pocket. This passing step is carried out as the receiving member remains at an elevated temperature at which the thermoplastic comprising the receiving member has a first elastic modulus. As a second step, the method comprises allowing the receiving member to cool to room temperature such that the thermoplastic comprising the receiving member has a second elastic modulus at room temperature that is lower than the first elastic modulus and that enables the deflecting member to retain the cylindrical pin within the receptacle. In this manner, the hinged article (preferably a hinged carrying case) can be quickly and easily formed as the receiving member exits its mold. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a double-walled blow molded carrying case of the present invention. 
     FIG. 2 is an enlarged partial exploded cutaway view of the handle receiving section and the handle member of the carrying case of FIG.  1 . 
     FIG. 3 is a side section view of a receptacle of the carrying case of FIG. 1 prior to the insertion of the handle member. 
     FIG. 4 is a side section view as in FIG. 3 with the handle member (shown in phantom line) inserted into the receptacle and in its retracted position. 
     FIG. 5 is a schematic side view of the double-walled blow molding process for forming the carrying case of FIG. 1, with the mold halves being open prior to the parison being lowered therebetween. 
     FIG. 6 is a schematic side view of the mold halves and parison of FIG. 5 with the parison lowered between the mold halves as they are in an open position. 
     FIG. 7 is a schematic side view of the mold halves and parison of FIG. 5 with the mold halves in a closed position. 
     FIG. 8 is a schematic side view of the mold halves of FIG. 5 showing the mold halves in an open position and the parison molded into the container and cover of the carrying case of FIG.  1 . 
     FIG. 9 is an enlarged perspective view of the mold inserts used in the molds in FIGS. 5-8. 
     FIG. 10 is an enlarged exploded view of one set of the mold inserts shown in FIG.  9 . 
     FIG. 11 is a side section view of a carrying case of FIG. 1 showing the insertion of the handle member into a receptacle. 
     FIG. 12 is a side section view as in FIG. 4 with the handle member (shown in phantom line) in an extended position. 
     FIG. 13 is a top view of the handle receiving section of the carrying case of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like components throughout. 
     Referring now to the drawings, a carrying case, designated broadly at  20 , is illustrated in FIG.  1 . The carrying case  20  includes a container  22  and a cover  24  that is pivotally interconnected with the container  22 . The hinge interconnecting the container  22  and the cover  24  (not shown) can be virtually any hinge configuration known by those skilled in this art to be suitable to interconnect such a container and cover; one exemplary hinge configuration is illustrated in U.S. Pat. No. 5,361,456 to Newby. The illustrated carrying case  20  thus has a container cavity  25  (FIG. 2) that is configured to contain, transport, and protect a power tool, such as a power drill. Those skilled in this art will appreciate that a carrying case of the present invention can take a variety of configurations and protect any number of items, such as electronic, computer, video, or camera equipment, sales samples, and the like. 
     As a double-walled blow-molded part, the container  22  has an outer wall  26  and an inner wall  28  (FIG.  2 ). As is typical of double-walled blow-molded parts, the outer wall  26  and inner wall  28  are in close proximity to one another and surround an internal cavity  27 . The container  22  includes some pinched-off areas (not shown) where the inner and outer walls  26 ,  28  are contiguous. 
     The container  22  is formed of a thermoplastic material, preferably polyethylene having room temperature elastic modulus of between about 80,000 and 260,000 psi at room temperature, suitable for blow-molding. Other suitable materials include polypropylene, polystyrene, acrylonitrile-butadiene-styrene (ABS), and copolymers thereof. It is preferred that the cover  24  also be formed of a thermoplastic material and have a double-walled construction, although those skilled in this art will recognize that other materials and structures are also suitable for use in the cover  24 . 
     At the peripheral edge  29  of the container  22  on the side of the container  22  opposite the hinge, the container  22  includes a handle receiving section  30  (FIGS. 2 through 4 and  13 ). The handle receiving section  30  includes a central portion  31  and a pair of mirror image receptacles  32   a,    32   b.  Those skilled in this art will appreciate that the receptacles  32   a,    32   b  are mirror images about a plane P bisecting the central portion  31  equidistant between the receptacles  32   a,    32   b.  As such, only the receptacle  32   a  will be described in detail herein; those skilled in this art will understand that this discussion is equally applicable to the receptacle  32   b.    
     Again referring to FIGS. 2 through 4 and  13 , the receptacle  32   a  is defined by a deflecting wall  34 , two stationary walls  38   a,    38   b  and two pockets  42   a,    42   b.  The pockets  42   a,    42   b  is preferably and illustratively defined by partial cylindrical surfaces, with cross sections describing a circular arc of approximately 180 degrees. The pockets  42   a,    42   b  are aligned along their longitudinal axes. Other arcuate configurations of the pockets  42   a,    42   b  may also be employed, although it is preferred that the cross-sections of the pockets  42   a,    42   b  define a circular arc of at least 180 degrees. The upper ends of the pockets  42   a,    42   b  merge with respective lower portions of the stationary walls  38   a,    38   b.  The stationary walls  38   a,    38   b  face the deflecting wall  34  and include coplanar and upright bearing surfaces  40   a,    40   b  that are parallel to the longitudinal axes of the pockets  42   a,    42   b.  The deflecting wall  34  is located between the pockets  42   a,    42   b.  The deflecting wall  34  has a bearing surface  36  that faces the direction opposite of the bearing surfaces  40   a,    40   b.  The bearing surfaces  36 ,  40   a,    40   b  are preferably generally planar, although the skilled artisan will understand that convex and concave bearing surfaces can also be employed. 
     As best seen in FIGS. 3 and 13, at their upper ends, the deflecting wall  34  and the stationary walls  38   a,    38   b  define an open end  44  of the receptacle  32   a.  The open end  44  (i.e., the dimension between the bearing surfaces  36 ,  40 ) is smaller than the width between the bearing surfaces  36 ,  40   a,    40   b  at their respective lower portions because the bearing surface  36  is tilted toward the bearing surfaces  40   a,    40   b.  This difference in width is preferably between about 30 and 40 percent of the width of the lower portions, or about 0.1 and 0.2 inches for the illustrated embodiment. The receptacle  32   a  also includes internal faces  46 ,  47  and end faces  48 ,  49 , each of which is normal to the stationary walls  38   a,    38   b  and the longitudinal axes of the pockets  42   a,    42   b.    
     A handle member  50  (FIGS. 2,  12  and  13 ) is pivotally attached to the container  22  for easy handling of the carrying case  20 . The handle member  20  includes an elongate grip segment  52 . Extensions  53   a,    53   b  extend from the respective ends of the grip segment  52  in a direction generally perpendicular to the longitudinal axis of the grip segment  52 . At each of the free ends of each of the extensions  53   a,    53   b,  a respective pin  54   a,    54   b  extends in both directions generally parallel to the grip segment  52 . 
     The handle member  50  is attached to the container  22  such that the ends of the pins  54   a,    54   b  are inserted into respective pockets  42   a,    42   b  of the receptacles  32   a,    32   b  (FIGS.  1  and  4 ). The pins  54   a,    54   b  fit and pivot within the pockets  42   a,    42   b,  thereby enabling the handle member  50  to pivot relative to the container  22  about the longitudinal axes of the pockets  42   a,    42   b.  This configuration enables the handle member  50  to take a gripping position, in which the grip segment  52  is spaced apart from the case outer wall  26  (FIG.  12 ), and a storage position (FIGS.  1  and  2 ), in which the grip segment  52  is adjacent the outer wall  26  beneath the handle receiving section  30 . Thus, the problem present in prior art carrying cases (namely, the inability to fold the handle away from an extended gripping position during storage) is addressed. 
     The process for blow-molding the container  22  and cover  24  can be best understood by reference to FIGS. 5 through 8. FIG. 5 schematically illustrates a pair of reciprocating mating mold halves  60 ,  70 . The mold halves  60 ,  70  are mounted on and reciprocated within a blow-molding machine (not shown) of a type and configuration known to those skilled in this art. Such a molding machine includes an overhead, vertically-directed extrusion head (not shown) that can produce a tubular thermoplastic parison  80  (see FIGS.  5  and  6 ). 
     Referring to FIGS. 5 and 6, the mold half  60  includes a pair of cavity portions  62   a,    62   b  that are recessed from and within the frame of the mold half  60  itself. The cavity portions  62   a,    62   b  includes contour and detail that is to be formed onto the outer walls  26  of the container  22  and the cover  24 . 
     The mold half  60  also includes two identical inserts  64   a,    64   b  in the upper cavity portion  62   a  (see FIGS.  9  and  10 ), only one of which will be described in detail herein. The insert  64   a  includes a pair of projections  65   a,    65   b  with opposed contact surfaces  66   a,    66   b  and a sloping deflecting wall forming surface  68  positioned between the contact surfaces  66   a,    66   b.  The inserts  64   a,    64   b  are positioned in the upper cavity portion  62   a  so they can contribute to the formation of the receptacles  30   a,    30   b.    
     The mold half  60  further includes cooling lines  69  (illustrated schematically in FIG. 8) which remove heat from the mold half  60  that is generated by repeated contact with molten thermoplastic parisons. Those skilled in this art will recognize that other cooling line configurations are also suitable for use with the present invention. 
     The mold half  70  (FIGS. 5 and 6) includes core portions  72   a,    72   b  that extend away from the frame of the mold half  70  and toward the mold half  60 . The core portions  72   a,    72   b  include contour and detail for forming the inner walls  28  of the container  22  and cover  24 . The mold half  70  also includes a cooling circuit  79  (FIG. 8) to remove heat generated by repeated contact with parisons. 
     The mold half  70  further includes two identical inserts  74   a,    74   b  in its upper core position  72   a,  only one of which will be described in detail herein. The insert  74   a  (FIGS. 9 and 10) includes a pair of facing contact surfaces  76   a,    76   b  and a pair of pocket forming projections  78   a,    78   b.  The insert  74   a  is positioned in the upper core portion  72   a  to mate with the insert  64   a  such that the contact surfaces  76   a,    76   b  brush against the contact surfaces  66   a,    66   b  during molding. 
     To initiate a molding cycle, the parison  80  of thermoplastic material is lowered from the extrusion head to a position between the mold halves  60 ,  70  (FIGS.  5  and  6 ). Once the parison  80  has reached a position between the mold halves  60 ,  70 , the mold halves  60 ,  70  close upon it (FIG.  7 ). This action pinches the parison  80  at its top and bottom portions and at lateral portions therebetween, thereby forming the aforementioned full-perimeter flash. In addition, a gas is introduced into the parison  80  through an inlet (not shown) in the extrusion head. Injection of this gas (preferably air or nitrogen) inflates the parison, which in turn forces the parison  80  against the cavity portions  62   a,    62   b  and the core portions  72   a,    72   b  of the mold halves  60 ,  70 . As the parison  80  is forced against the core and cavity portions  62   a,    62   b,    72   a,    72   b,  it takes the contour of these parts of the mold halves  60 ,  70 . 
     As the mold halves  60 ,  70  close, the insert  64   a  mates with the insert  74   a;  similarly, the insert  64   b  mates with the insert  74   b.  As the inserts  64   a,    74   a  mate, their contact surfaces  66   a,    66   b,    76   a,    76   b  brush against each other. As a result, thermoplastic from the parison  80  is blocked from penetrating end flowing between the contact surfaces. The pocket forming surfaces  78   a,    78   b  form the pockets  42   a,    42   b  and the adjoining stationary walls  38   a,    38   b.  The deflecting wall forming surface  68  forms the deflecting wall  34 . 
     The mold halves  60 ,  70  remain closed until the thermoplastic material has cooled sufficiently to be handled without affecting its new configuration. The mold halves  60 ,  70  then open, and the container  22  and cover  24  are ejected (FIG.  8 ). 
     After molding, the container  22  and cover  24 , which are spaced apart by a section of flash material  82 , are separated and assembled. Also, sections of flash material  84  that extend from the lower edge of the cover  24 , the upper edge of the container  22 , and the lateral edges of each are removed. 
     Notably, the mold halves  60 ,  70  are configured so that the container  22  is molded simultaneously with the cover  24 . This dual molding process is preferred, as the appearance of these parts, which can vary slightly based on material lot, mold temperature, mold aging, and other factors, should more closely match one another. 
     Interconnection of the handle member  50  with the container  22  can be best understood by reference to FIGS. 3,  4  and  11 . As the container  22  is ejected from the mold halves  60 ,  70 , the thermoplastic comprising the container  22  has frozen, but is still hot. The temperature of the thermoplastic depends on the type of thermoplastic used; for polyethylene, the temperature is generally between about 100 and 150 degrees Fahrenheit. Because it is well above room temperature, the thermoplastic has a lower elastic modulus than it would at room temperature. As such, the structures of the container  22 , and in particular the deflecting wall  34 , are more flexible immediately after ejection than after cooling to room temperature. Thus, as each of the pins  54   a,    54   b  of the handle member  50  is forced through the open end of a respective receptacle  32   a,    32   b,  each deflecting wall  34  deflects such that its upper end travels away from the stationary walls  38   a,    38   b  it faces. This movement enables each pin  54   a,    54   b  to pass between the stationary walls  38   a,    38   b  and the deflecting wall  34  (FIG. 11) and into its pockets  42   a,    42   b  (FIG.  4 ). In this position, the pins  54   a,    54   b  can rotate within their pockets  42   a,    42   b,  thereby enabling the handle member  50  to rotate between extended (FIG. 12) and retracted (FIG. 11) positions. 
     Once the pins  54   a,    54   b  are in their respective pockets  42   a,    42   b  the deflecting walls  34  return to their original positions to decrease the width of the open ends  44  of the pockets  42   a,    42   b.  This movement retains the pins  54   a,    54   b  in the pockets  42 . As the container  22  cools, the elastic modulus of the thermoplastic continues to rise until the container  22  reaches room temperature. The increased stiffness of the thermoplastic assists the handle member  50  in remaining in place. Preferably, the ejection temperature of the thermoplastic is selected so that the ratio between the ejection temperature elastic modulus and the room temperature elastic modulus is between about 1.5 to 1 and 10 to 1. Of course, this method can be carried out after the container  22  cools, but the insertion force required is typically much higher. 
     The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.