Abstract:
A peripherally encapsulated unit is manufactured by molding a peripheral encapsulation of a predetermined internal peripheral contour and internal peripheral size from hot polymeric material in a mold. The mold is opened and a member is positioned in internal relationship to the hot molded peripheral encapsulation. Thereafter, the hot molded peripheral encapsulation shrinks as it cools to reduce its internal peripheral size thereby unitizing the peripheral encapsulation with a peripheral edge portion of the member to form a peripherally encapsulated unit, such as a cook top, range door, “touch” control panel, or the like.

Description:
BACKGROUND OF THE INVENTION 
     Heretofore it has been conventional to provide a support frame for receiving and retaining a panel of glass as part of a wall or door assembly. Such a support frame includes an integrally formed body of uniform cross section defining a generally inwardly opening channel as disclosed in, for example, U.S. Pat. No. 4,914,888 in the name of Laurence B. Hanson which granted on Apr. 10, 1990. Screws are inserted through an opening in one side wall of the channel and are threaded into an opening in a second side wall of the channel to draw the two side walls into gripping contact with the glass panel, thus providing a relatively unitized and rigid supporting frame. 
     Typical also of a frame of this type is such as that disclosed in U.S. Pat. No. 3,363,390 in the name of Jameson Crane granted on Jan. 16, 1968. The frame member in this case is extruded and is folded around a peripheral edge of an associated panel with a screw uniting a single corner of the frame. 
     More recently it has become conventional to insert a panel in a mold, isolate a peripheral edge portion of the panel and injection mold a polymeric/copolymeric frame about the edge of the panel. Such frames are utilized as front and rear windshields for automobiles or other glass panels for vehicles or buildings, as is reflected in U.S. Pat. No. 4,695,420 granted on Sep. 22, 1986 to Charles E. Grawey et al. and U.S. Pat. No. 4,626,185 granted on Dec. 2, 1986 to Bernard Monnet. 
     Such injection molded encapsulation is now conventional in shelving, particular for refrigerators, as is evidenced by U.S. Pat. Nos. 5,273,354; 5,362,145; 5,403,084; 5,429,433; 5,441,338 and 5,454,638 issued respectively on Dec. 28, 1993; Nov. 8, 1994; Apr. 4, 1995; Jul. 4, 1995; Aug. 15, 1995 and Oct. 3, 1995, all assigned to the assignee of the present application. 
     Typically, such shelves are manufactured in an injection mold of the type disclosed in pending application Ser. No. 08/303,200 filed on Sep. 8, 1994 in the names of Max Meier et al. In the latter disclosure a glass plate or panel has its peripheral edge located in a peripheral cavity into which highly pressurized plastic material is injected and, upon subsequent cooling, the edge of the panel is bounded by a polymeric frame or encapsulation which, since intended for use as a refrigerator shelf, has also integrally unitized thereto opposite metallic shelf brackets. A cook top is manufactured similarly in pending application Ser. No. 08/890,651 filed on Jul. 9, 1997. 
     SUMMARY OF THE INVENTION 
     In keeping with the forgoing, a primary object of the present invention is to provide a novel and unobvious method of manufacturing a peripherally encapsulated unit, such as a refrigerator shelf, a range oven door, a microwave oven door, a cook top, a hob top, a “touch” control panel or the like. Preferably, an injection mold is provided which defines a peripheral cavity in which can be injection molded a frame or encapsulation having an inwardly opening preferably continuous channel. At the completion of the injection molding of the frame, the cavity is at least partially opened, and a panel, such as a Ceran® or glass panel, is moved into the mold into alignment with a channel of the still hot injected frame or encapsulation. A peripheral edge of the panel is maintained in alignment with the channel of the encapsulation as the latter cools. The cooling of the encapsulation or injection molded frame results in the shrinkage thereof which brings the channel into progressive intimate embracing relationship to a peripheral edge of the glass or Ceran® panel eventually resulting in a unitized peripherally encapsulated unit which can, for example constitute a cook top, a door for a range oven, a “touch” control panel for an oven, range or the like wherein the Ceran®/glass panel includes so-called “touch” circuitry, or similar structures. One major advantage of the aforesaid method is that during the molding thereof, the panel need not be inserted into the mold and subject to heat and pressure which is highly undesirable, particularly in such applications as “touch” control panel circuitry, the electronics of which can be adversely effected under relatively high molding temperatures. Thus, no matter the material from which the “insert” member might be made, it is subject to less pressure and temperature than heretofore noted and only the peripheral edge thereof is briefly subject to elevated temperature as the encapsulation/frame cools and shrinks into conformity with the periphery of the insert. Thus, relatively close tolerances can be maintained at high production output and at minimum deterioration, as might not otherwise occur under elevated injection molding temperatures and pressures. 
     With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary diagrammatic perspective view of a mold of the present invention, and illustrates upper and lower mold bodies and a central mold core defining a peripheral cavity in which has been injection molded a polymeric/copolymeric encapsulation or frame and externally of which a relatively flat panel of Ceran® panel, glass or the like is supported by vacuum cups of a movable vacuum cup mounting plate. 
     FIG. 2 is a fragmentary diagrammatic cross-sectional view of the mold of FIG. 1, and illustrates the lower mold body and central mold core in their open positions with the movable vacuum cup mounting plate and Ceran®/glass panel positioned identically as shown in FIG.  1 . 
     FIG. 3 is a fragmentary diagrammatic cross-sectional view of the mold of FIGS. 1 and 2, and illustrates the central mold core moved upwardly, the vacuum cup mounting plate moved upwardly, and a peripheral edge of the Ceran®/glass panel aligned with a channel of the injection molded frame or encapsulation. 
     FIG. 4 is a fragmentary diagrammatic cross-sectional view of the mold of FIGS. 1 through 3, and illustrates the manner in which the encapsulation has cooled and shrunk into intimate gripping contact with the peripheral edge of the panel, and the removal of the peripherally encapsulated unit from the mold cavity. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A mold  10  is illustrated in the fully closed position thereof in FIG. 1 of the drawings, and includes an upper mold body or cavity steel  11 , a lower mold body or cavity steel  12 , and an inner central mold or core steel  13  beneath which and spaced therefrom is a vacuum cup mounting member or plate  14  which carries a plurality of vacuum cups  15  connected conventionally through valved lines (not shown) to a source of negative air pressure (also not shown). 
     The upper mold body  11  is of a generally open polygonal frame-like configuration defined by an upper surface  21 , a lower surface  22 , an inner peripheral surface  23 , a medial annular surface  24  and three cavity-defining surfaces  25 ,  26  and  27  with the surfaces  25 ,  26  and  26 ,  27  merging at rounded radius surfaces (unnumbered). The cavity-defining surfaces  25 ,  27  are substantially in parallel relationship to each other, and each is substantially normal to the cavity-defining surface  26 . 
     The lower mold body  12  is also of a generally frame-like configuration and includes an upper cavity-defining surface  32 , a lower surface  33  and an inboardmost peripheral surface  34 . The lower mold body  12  is of a multi-part movable construction and can be moved in a conventional manner from the closed position shown in FIG. 1 in which the surfaces  25  through  27  and  32  define a closed frame-like mold cavity  35  and an open position (FIG. 2) in which the various lower mold body portions or segments  12  are retracted to an open position at which the inboardmost peripheral surface  34  of the lower mold body  12  is outboard of the cavity-defining surface  25  of the mold cavity  35  of the upper mold body  11 . 
     The inner mold body or core steel  13  includes an uppermost surface  41 , a lowermost surface  42  and three outer peripheral surfaces  43 ,  44  and  45 , the latter of which is joined to the two former surfaces by respective annular surfaces  46  and  47 . The surfaces  44 ,  45 ,  46  and a portion of the surface  47  essentially define the cross-section configuration of the closed mold cavity  35  and specifically define the innermost peripheral configuration thereof in the manner clearly illustrated in FIG.  1 . The inner mold body  13  is also a segmented mold body and segments or portions thereof can be shifted inward to an open position (FIG. 2) for purposes to be hereinafter described. 
     Conventional injectors I, such as the four conventional injectors  60  shown in FIG. 5 of application Ser. No. 08/303,200, are provided to inject hot polymeric/copolymeric synthetic plastic material under pressure into the mold cavity  35  in the closed position thereof (FIG.  1 ), preferably at each of the four corners (not shown) of the mold cavity  35  to form an opened frame, frame member or encapsulation F under heat and pressure during the conventional molding cycle of an associated injection molding machine. 
     Shortly prior to or during the injection of the pressurized hot plastic material into the mold cavity  35 , a generally polygonal/rectangular piece of glass, Ceran® panel or like material G is located in accurate centered relationship to the overall mold  10  and particularly relative to the mold cavity  35 . The panel, insert or inner member G includes a peripheral edge P 1  which is accurately sized to correspond in shape, size, configuration and overall dimensions to the shape, size, configuration and overall dimensions of the outermost peripheral surface  44  of the inner mold body  13  when closed (FIG.  1 ), but is ever so slightly smaller in each of its shape, size and configuration and overall dimensions. The slightly smaller shape, size and overall dimensions, including the peripheral dimensions of the glass member G, permits the peripheral edge P 1  thereof to be inserted to within, through and beyond) a lowermost peripheral surface LPS of the molded frame or encapsulation F formed by injection in the mold cavity  35  after the inner mold body  13  has been shifted to its open position (FIG.  2 ). An imaginary alignment line L shown in FIG. 2 reflects the close tolerances between the peripheral edge P 1  of the inner member G and the lower peripheral surface LPS of the frame or encapsulate F which, upon upward movement of the inner mold body  13  and the vacuum cup mounting member  14  in the manner shown in FIG. 3, brings the member or panel G to the position shown in FIG. 3 at which its peripheral surface P 1  is in alignment with an opposing surface (unnumbered) of the encapsulate F formed by the surface  45  of the inner mold body  13  and in part defining therewith a (peripherally inwardly opening continuous channel) groove or slot C. A peripheral space S (FIG. 3) exists between the innermost bottom peripheral surface (unnumbered) of the continuous channel C and the peripheral edge P 1  of the inner member G at and shortly after the time that the mold  10  has been opened and while the encapsulation F remains hot. However, as the encapsulation F cools, the material thereof shrinks and eventually the space or gap S is closed (FIG. 4) which allows the encapsulation F to shrink over, clamp to and bond with the entire peripheral/polygonal edge portion (unnumbered) of the inner member G forming a peripherally encapsulated unit U (FIG. 4) which might be, for example, a door for an oven, a door for a microwave oven, an electronic “touch” control panel or a cook top, such as the ceramic cook top and/or hob top disclosed in U.S. Pat. Nos. 5,036,831; 5,185,047; 4,243,016; 4,363,956; 4,580,550 and/or 4,453,533. Thus, in keeping with the present invention, the Ceran®, glass or like panel G need not be separately post attached to the frame F after cooling and/or mold ejection, nor is the panel G adversely effected by being held in a mold body while the periphery thereof is encapsulated by hot injection molded polymeric/copolymeric material which could adversely effect circuitry of “touch” control panels, as occurs with conventional practices earlier herein mentioned. The peripherally encapsulated unit U is, therefore, capable of rapid and repetitive low cost manufacture absent disadvantages of prior art post assembly or in-mold injection assembly, as is presently conventionally practiced. 
     Although a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the apparatus without departing from the spirit and scope of the invention, as defined the appended claims.