Abstract:
The invention relates to a dynamic mold seal for use in a method of molding apparatus to mold a polymeric frame or gasket onto the periphery of a glass sheet. The seal and method are preferably utilized to form a vehicle window.

Description:
BACKGROUND OF INVENTION 
       [0001]    The invention relates to a mold seal which allows an improved method of molding a polymeric material onto at least a portion of the periphery of a sheet of substrate material. More particularly, the invention relates to utilizing the subject seal in a molding apparatus to mold a polymeric frame or gasket onto the periphery of a glass window for a vehicle. 
         [0002]    It is known to mold an elastomeric gasket or frame member onto the periphery of a substrate such as glass to form products such as vehicle windows. Common molding methods are reaction injection molding (RIM) and injection molding. Such molded-on members have become increasingly complex and, as a result, the molding apparatus used in making such molded-on members have likewise become more complex. 
         [0003]    To create the profiles desired in such elastomeric members, it is sometimes necessary to manage the flow of the polymeric molding material within the molding apparatus. Among the methods utilized for such management of liquid polymeric molding material are so-called “soft seals.” In typical known soft seals, it is often necessary to have a soft seal in opposing relationship on each major surface of the substrate onto which the gasket is to be molded. Such seal configurations generally do not permit molding up to the edge of the major surface of the substrate, which can be a detriment, both aesthetically and functionally. Therefore, it would be desirable to have a method of molding requiring a single soft seal that would permit complex molded profiles extending to, and even beyond the edge of a major surface of the substrate. 
       SUMMARY OF THE INVENTION 
       [0004]    The invention relates to a mold seal which allows, in a simple and cost-effective manner, an improved method of molding a polymeric material onto at least a portion of the periphery of a sheet of substrate material. More particularly, the invention relates to utilizing the subject seal in a molding apparatus to mold a polymeric frame or gasket onto the periphery of a glass window for a vehicle. Still more particularly, the invention relates to a dynamic mold seal which, working in cooperation with at least one movable mold portion, permits molding up to the edge of a major surface of a sheet of substrate material, or even beyond the edge of a major surface of a sheet of substrate material if desired. 
         [0005]    The dynamic mold seal of the invention includes a base portion, an intermediate portion, a straight arm portion and a flexible arm portion. Preferably, the subject mold seal is an integral assembly including the previously mentioned elements. In any desired configuration, the intermediate portion extends from the base portion, and the straight and flexible arm portions extend from the intermediate portion, but in different directions from one another. The flexible arm is capable of movement due to the presence of an “elbow,” allowing the flexible arm to move into and out of sealing contact with at least a portion of a peripheral edge of the sheet of substrate material. At the same time, the straight arm portion is adapted to sealingly engage at least a portion of a major surface of the substrate material. 
         [0006]    The invention also relates in another aspect to the utilization of the previously described dynamic mold seal in a molding apparatus to form an encapsulated substrate, such as a vehicle window having a molded-on frame or gasket. 
         [0007]    The molding apparatus in which the dynamic seal is utilized includes upper and lower mold halves, either or both of which may have a mold cavity formed therein. In a mold half containing a mold cavity, a seal cavity will also be formed to receive the base portion of the dynamic seal of the invention. At least one movable mold portion is also included in the mold half having the seal cavity. The at least one movable mold portion is located so that the flexible arm portion of the dynamic seal is within the range of movement of the movable mold portion. 
         [0008]    In preparing to conduct a molding operation, the dynamic seal of the invention will have been affixed in the cavity seal. A sheet of substrate material, for example a glass vehicle window, will be placed in the mold cavity such that at least a portion of the peripheral edge of the vehicle window is proximate the dynamic seal of the invention. The straight arm portion of the seal is in sealing contact with a major surface of the vehicle window; that is, the inner major surface of the vehicle window. Closure of the mold halves actuates the movable mold portion, causing it to come into pressing contact with the flexible arm of the seal of the invention. The flexible arm is deflected toward, and into sealing contact with, at least a portion of the peripheral edge of the vehicle window. Then, liquid polymeric material is injected into the molding apparatus to fill the mold cavity. Due to the action of the seal of the invention, such liquid polymeric material is prevented from coming into molding contact with either of at least a portion of the peripheral edge of the vehicle window or a portion of the inner major surface of the vehicle window. A polymeric frame or gasket is formed, however, around the remaining portion of the periphery of the vehicle window. 
         [0009]    The liquid polymeric material is allowed to cure in the mold cavity and thus bond to the at least a portion of the periphery of the vehicle window. Once sufficient curing has occurred, the mold halves are opened, and the movable portion of the mold retracts from its extended position, releasing the pressure exerted on the flexible arm of the subject seal. The flexible arm of the seal moves away from the periphery of the now-encapsulated vehicle window, which can be removed from the mold cavity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The advantages described herein, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiment when considered in light of the accompanying drawings. 
           [0011]      FIG. 1  is a perspective view of a lower mold half of the molding apparatus according to the invention. 
           [0012]      FIG. 2  is a cross-sectional view of the upper and lower mold halves in molding contact and containing the subject dynamic seal according to the invention. 
           [0013]      FIG. 3  is a cross-sectional detailed view of the molding apparatus according to the invention, particularly illustrating the movable mold portion interacting with the dynamic seal. 
           [0014]      FIG. 4   a - c  are cross-sectional views of the profiles of representative frames or gaskets which can be molded utilizing the seal and method of the present invention. 
           [0015]      FIG. 5  is a cross-sectional view of a molding apparatus containing a soft seal typical of those known from the patent literature. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Molding of an elastomeric frame or gasket onto the periphery of, for example, a vehicle window to form a so-called modular window assembly, which can then be conveniently installed in an opening in a vehicle body, is well known. Even so, placing a piece of glass into an injection molding apparatus and subjecting it to several thousand pounds per square inch of molding pressure in order to mold on the periphery thereof a polymeric frame or gasket without breaking the glass while obtaining a strong bond between glass and the polymeric frame or gasket, presents a number of technological challenges. 
         [0017]    As previously noted, highly complex molding apparatus to create complex molding profiles have been proposed. Typically, such apparatus have one or more means of directing the liquid polymeric molding material to a particular area of the mold, or conversely, preventing the flow of the polymeric material into a particular portion of the mold. As previously noted, movable mold portions and so-called “soft seals” are among these means. An example of a typical known soft seal is illustrated in  FIG. 5 . The typical, previously known soft seal illustrated in  FIG. 5  requires opposing seals  60  and  62 . The soft seals shown in  FIG. 5  do not allow molding up to or even over the edge of a vehicle window during a molding operation. Also, while typical soft seals allow for some variation in glass dimensions and configuration, they are, generally, quite limited in this regard. Typical soft seals are also susceptible to being dislodged from their position in the mold by the pressures in the mold created by the molding operation. This is particularly, an issue with injection molding processes. 
         [0018]    The mold seal of the invention, by contrast, is relatively simple in that only a single seal is necessary, rather the two or more as shown in  FIG. 5  herein, while allowing molding up to and beyond the peripheral edge of the glass sheet, as well as accommodating significant variations in glass size and shape during the molding process. Further, the cooperation between a movable mold portion and the present mold seal not only causes the effective functioning of the mold seal, by allowing it to move into and out of sealing engagement with the substrate, but the movable mold portion assists in preventing the mold seal from being dislodged from the mold cavity during the molding operation. 
         [0019]      FIG. 1  shows a mold half  10  of the invention having a mold cavity  12  which will receive the liquid polymeric molding material. One or more means of conveying the polymeric material (not shown) into the mold cavity  12  will be present, e.g. one or more sprues and a cold/hot runner system, but are well known and not part of the invention. When placed into the mold half  10 , the glass sheet  14  will be supported by one or more resilient support members  16  proximate seal cavity  18  and within the range of movement of movable mold portion  20 . As will be described in more detail, the base of mold seal  22  is configured to be insertable into seal cavity  18 . Lower mold half  10  can be made of steel, aluminum or other suitable material. 
         [0020]      FIG. 2  is a cross-sectional view of the lower mold half  10  of  FIG. 1  in intimate molding contact with upper mold half  24 . A glass sheet  14  is in the closed molding apparatus ready for the molding operation to occur. Similar to lower mold half  10 , upper mold half  24  may be made from aluminum, steel or other suitable material. 
         [0021]      FIG. 3  shows the mold seal  22  of the invention as shown, generally, in  FIG. 2  in greater detail. As can be seen, the mold seal  22  of the invention is comprised of a base portion  26  configured to be inserted into seal cavity  18 , an intermediate seal portion  28  which connects the base portion  26  of the seal with the flexible arm  30 , and straight arm  32 . Mold seal  22  can be made from any suitable resilient polymeric material, for example, EPDM, silicone and thermoplastic elastomers (TPE), as well as combinations thereof. 
         [0022]    Flexible arm  30  and straight arm  32  extend from the intermediate seal portion  28  in different directions from one another, such that straight arm  32  sealingly contacts a major surface  34  of glass sheet  14 . By contrast, flexible arm  30 , made “flexible” by virtue of an elbow portion, for example, a cut-out  36  or other suitable means, is positioned proximate peripheral edge  38  of glass sheet  14 . Under non-molding conditions, flexible arm  30  is not in contact with peripheral edge  38 . During molding operations, movable mold portion  20  will urge flexible arm  30  into sealing contact with peripheral edge  38  as illustrated in  FIGS. 2 and 3 , the direction of movement of the movable mold portion  20  being particularly shown by the arrow. Flexible arm  30  is capable of movement of on the order of 10°-15°. The point at which flexible arm  30  contacts peripheral edge  38  can be adjusted so as to allow the liquid polymeric molding material to bond to varying proportions of the peripheral edge of the glass sheet so as to form different molding profiles, as illustrated in  FIG. 4 . Movable mold portion  20  is activated upon the closing of upper and lower mold halves  24  and  10 . After completion of a molding cycle, the mold halves  24  and  10  are opened, the movable mold portion retracts, thus allowing flexible arm  30  to once again move out of molding contact with peripheral edge  38 . 
         [0023]    It is within the scope of the invention for mold seal  22 , seal cavity  18  and movable mold portion  20  to be present only in selected portions of the periphery of glass sheet  14 , as well as to be present around the complete periphery of glass sheet  14  as shown in  FIG. 1 . 
         [0024]      FIG. 4  illustrates some of the versatility of mold seal  22 .  FIG. 4   a  shows the capability of molding up to the transition between major surface  40  and peripheral edge  38  of glass sheet  14 .  FIG. 4   b  shows how, with adjustment of the position of mold seal  22 , molding past the transition point between major surface  40  and peripheral edge  38  to an intermediate position on the edge of the glass sheet can be accomplished. Finally,  FIG. 4   c  shows how the mold seal  22  of the present invention can be utilized to mold a polymeric frame, gasket or the like to form a so-called two-side encapsulation; i.e., a peripheral portion of a major surface and a peripheral edge of a glass sheet. 
         [0025]    In accordance with the provisions of the patent statutes, the principles and mode of operation of the present invention have been described in what is considered to represent the preferred embodiment. It should be understood, however, that the invention may be practiced otherwise than as specifically illustrated and described without departing from the scope of the claims herein.