Abstract:
A one piece mold, having a cavity into which fluid material is fed through an input port, to result in a seamless, cast icon. At least the input port portion of the mold is sufficiently elastic so that it can be stretched open: (a) by the hardened icon, when positive pressure is applied into the cavity, remote from the input port; (b) by negative pressure applied around the mold, at least proximate to the input port; or (c) by a combination of such applied positive and negative pressures; to demold through the input port, the then hardened icon. An endless conveyor system carries the molds past several stations, including an icon demolding station, which applies the mold stretching pressure for the icon domolding. The applied pressure(s) does not exceed the elastic capability of the mold, so that it can be reused repeatedly, without deterioration as to form and shape of the icon.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 60/254,629, filed on Dec. 11, 2000, entitled MOLDING PROCESS EMPLOYING PRESSURIZED DEMOLDING; AND PRODUCTS MADE THEREBY. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention concerns the manufacture of, cast molded objects, especially the mold, and the process of removing that object from the mold.  
         BACKGROUND OF THE INVENTION  
         [0003]    The manufacture of cast molded objects of different materials, sizes and uses is an ancient art, which has been improved upon in many ways, while retaining basic attributes of mold making, mold filling and mold emptying of the casting. The casting often is the finished product; or requires additional processing steps. The manufacture of cast or molded objects often is labor intensive and the initially demolded object often is of varying quality, as compared to the same object from the same mold, made recently prior to or soon after.  
           [0004]    It would require volumes of information to discuss the history/background of molding process and apparatus, even if this background was limited to one-piece molds into the cavity of which fluid material is poured, the mold cavity being the negative of the resulting object. However, inasmuch as the present invention employs an elastic, one piece mold, it is appropriate to mention the prior art use of glove molds. Glove molds are very elastic and typically are of a thin material, having limited reusability. When the object in the glove mold has hardened, the thin mold manually is peeled back and off of the molded object. This type of demolding is labor intensive and slow; with the possibility of the molded object being broken during the peeling off of the mold, unless there is careful handling.  
         SUMMARY OF THE INVENTION  
         [0005]    As employed hereinafter, the cast molded, resulting object will be identified by the term “icon”, which is intended for any shape. The size, shape and volume of the icon can lie within a large range and primarily is limited by practical cooling/hardening time of the fluid material which is fed into the mold. The terms “elastic”, “flexible” and “resilient” are employed for the mold material in their normal technical meaning; however, the terms “expansion” and “stretching” of the mold material are to mean that, when the mold is reused, its cavity has returned to its original shape; whereby, numerous reuses of a cavity will result in nearly identical icons. The term “pressure” includes both, positive and negative (vacuum) pressure.  
           [0006]    The present invention, its mold, molding and demolding system and process, produce a finished icon product more reliably, with less labor and cost. The mold is one piece, of elastic material, such as vulcanized rubber, having an internal cavity which is the negative of the object being molded. The mold has an input port for receiving the usually heated, liquid material, for filling the cavity. After the molded icon object has hardened sufficiently in the cavity, a source of air pressure is coupled to the mold and causes the icon object to be ejected or released out through the input port, which has been expanded sufficiently for the icon to leave the mold as a finished product. Ejection of the icon from the cavity of the mold can be by use of positive pressure into the cavity, via a second port, remote from the input port; whereby, the hardened icon is blown out the input port. Another manner of icon removal can be by use of vacuum, which is applied to exterior of the mold to thereby stretch it outwardly and enlargen the cavity, to free the icon. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0007]    [0007]FIG. 1 is a side elevation of the grommet-like mold;  
         [0008]    [0008]FIG. 2 is a top view of the mold of FIG. 1;  
         [0009]    [0009]FIG. 3 is a bottom view of the mold of FIG. 1;  
         [0010]    [0010]FIG. 4 is a sectional view, taken along line  4 - 4  of FIG. 1;  
         [0011]    [0011]FIG. 5 is a pictorial side view of a system, using the mold of FIG. 1, for manufacturing according to the invention;  
         [0012]    [0012]FIG. 6 is a pictorial top view of the input portion of the system of FIG. 5; and  
         [0013]    [0013]FIG. 7 is a pictorial side view of an alternate demolding station of the system of FIG. 5. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0014]    As this description progresses, it will become evident that there can be employed numerous variables in: the design of the mold, the mounting of the mold into the conveyor portion of the system, and in fact almost all of the mechanics of the embodied system, without departing from the elastic capability of the mold during the pressurized demolding of the product. Icons well suited to be made according to this invention are decorative items, such as candles, parts of candles, soap, air fresheners, etc; however, larger and/or more complex icons can be the result of this invention.  
         [0015]    As shown in FIGS. 1 and 2, there is a mold  10  having sufficient interior shape and volume to contain a cavity  12 , which is the negative of the icon  14 , for example a strawberry shaped piece of candle or soap. The material of the mold  10  is to be elastic, such as vulcanized rubber, silicon and polyurethane resin, such that at least the portion  16  of the mold, between the input port  18  or sprue and the widest part of the icon  14 , can be made to expand/stretch sufficiently for the icon to be forced/pushed/dropped out from the cavity  12 , without structural damage to the mold or the icon.  
         [0016]    Although the mold  10  will be one piece or unitary, it can be a composite unit, of which the portion  16 , proximate the port  18  and the cavity  12 , is elastic; and a portion  17 , remote from the cavity, is more rigid, for longer life of the mold. FIG. 4 does not show where the portions  16  and  17  meet, since that would be determined by the size, shape and position of the cavity  12 .  
         [0017]    The mold material, at least its cavity portion  16  and input port  18 , usually needs to be able to receive heated liquids, which will be cast in the cavity  12  to form the icon  14 . Temperatures of 50° C. to 150° C. are typical in the use of “waxes”, such as paraffin, polymide candle mixtures, vegetable fats, etc., having relatively low viscosity when heated to liquid or pourable consistency and then harden to yield the resulting icon. Mold material having high heat transfer is believed desirable, so that the icon material can cool and harden more quickly. It is envisioned that the liquid temperature could be as high as 400° C., without damaging the mold. The material for the icon can be self-hardening, of the well known types which are flowable, even when not heated, but harden by inclusion of a curing substance. Cooling/hardening time in the mold can be as short as ten minutes, but could be as long as eight hours, depending upon the “wax” or other flowable substance and the volume and shape of the cavity. As will be discussed subsequently with reference to FIG. 5, the mold could be put into a cooling or hardening chamber, to decrease the time needed for the icon to harden sufficiently to be ejected from the mold.  
         [0018]    With reference to FIGS. 3 and 4, the mold  10  can be provided with a second port  20 , a fluid pressure input port. The pressure input port  20  conveniently is locatable at the bottom of the mold, but could be located elsewhere, as long as its interior end  22  opens into the cavity  12  at a location appropriate for applying fluid pressure upon the hardened icon  14 , to push or eject it out of the cavity  12 , through the expansion portion  16  and out from material input port or sprue  18 , which thereby become deformed. Air pressure in the range of 20 to 120 p.s.i. has been found effective, depending on the material of the mold, the material of the icon and its mass, shape, and volume. Gases and liquid other than air can be employed for ejecting the icon. Vacuum also can be the demolding force, without need for the port  20 , as will be disclosed subsequently.  
         [0019]    Looking next at FIGS. 5 and 6, which are pictorial side and top views one embodiment of a molding system, for using the mold  10 , there is shown a conveyor belt  24 , of the endless type. Positioned into the belt  24  are a few of the molds  10 . For this embodiment, the belt  24  has numerous round holes  26 , into each of which can be seated a mold. Each mold is provided with a groove  28 , like a grommet, as shown in FIGS. 1, 4 and  5 , with the belt  24  lying around the groove  28 , as shown in FIG. 5. The holes  26  can be other than round or circular to accommodate and mate with the periphery of the groove  28 , if that periphery is other than circular. The belt is shown driven clockwise, causing the molds on the top of the system to move from the left to right. Above the top left end of the belt is a mold filling station  30 , having one or more hoppers  32  and associated infeed nozzles  34 . One hopper can feed into several nozzles, as shown in FIG. 5, or there can be several hoppers  32 , each dedicated to a single nozzle, as shown in FIG. 6. The hopper  32  can be filled with flowable/liquid substance and possibly have a warming coil or other warming and stirring means (not shown) for the icon material; or the hopper can be equipped to receive solid, waxy material for melting it into condition for delivery through a nozzle  34  into the input port  18  of a mold  10 . The feed through the nozzle can be by gravity alone or by use of a small amount of pressure.  
         [0020]    After leaving the filling station  30 , the molds  10  advance along (to the right in FIGS. 5 and 6) while the icons  14  cool and/or begin to solidify. The speed of the conveyor can be about  50  centimeters a minute until the icons harden. If required, a cooling station  36  can be provided to reduce the cooling time. If the material used to make the icon contains hardening agents, the station  36  can be equipped with known means to reduce the hardening time. Further along the path of the conveyor belt  24 , for example where the belt becomes inverted on its return path, there is an ejection station  38 , having a manifold or plenum  40  and one or more pressure nozzles  42 . When a mold  10 , with its hardened icon  14 , reaches the ejection station  38 , one embodiment of that station forces enough fluid/air pressure into the pressure port  20  of the mold to blow the icon out through the infeed port  18  and into a receiving basket  44 , which itself can be a conveyor leading to a sorting and packing station, not shown.  
         [0021]    [0021]FIG. 7 shows another embodiment  45  of a demolding station, which operates on negative pressure/vacuum to separate the hardened icon from the mold and enable the icon to pass out from the input port  18  and place the icon into the receiving basket  44 . The use of this demolding station  45  eliminates the need for the fluid pressure port  20  in the mold  10 . As shown in FIG. 7, the conveyor belt  24  brings the mold  10  with its hardened icon  14  into the negative pressure station  45 . Thereupon, negative pressure is applied around least the elastic portion  16  of the mold  10 , to thereby expand, stretch or open the input port  18  and if necessary enlargen the cavity  12  sufficiently for the icon  14  to be released from the mold  10 , for receipt by the basket  44 .  
         [0022]    For ease of understanding the operation of the demolding station  45 , FIG. 7 is shown greatly enlarged over FIG. 5. The station  45  defines a vacuum chamber  46 , which surrounds the mold  10 ′ and forms an air tight seal at a surface area of contact  48 . The chamber  46  is sufficiently larger than the exterior of the mold  10 ′, so that when a vacuum is drawn, by means not shown, the elastic wall portion  16  of the mold, including input port  18 , will be expanded outward toward the adjacent walls of the vacuum chamber, in the direction of the arrow heads  50 . Such expansion also increases the volume of the mold cavity  12  and frees/releases/demolds the icon, so that its only support is the conveyor belt  24 . If, as shown in FIG. 7, the conveyor belt  24  lies below the vacuum chamber  46 , the chamber can be reciprocated vertically, as shown by the two-headed arrow  52 , from the position shown in FIG. 7 to an elevated position, not shown, above the mold  10 ′; both prior to and subsequent to the demolding position shown in FIG. 7. Thus, the mold  10 ′ would be advanced on the belt  24  until the mold is below the vacuum chamber  45 ; then the chamber would be lowered to encompass the mold and demold the icon  14 ; after which the chamber  46  would be re-elevated, to permit the demolded icon to advance toward the basket  44 . In such an orientation of the demolding station  45 , the basket would be positioned near the beginning of the return path of the conveyor.  
         [0023]    The cross-sectional surface area of the sprue or input port  18  can be larger than shown in FIGS. 4 and 7; and the cavity  12  can be as simple as cylindric; with relatively straight walls lying generally parallel to the exterior of the mold. Most important is that the size, shape and position of the cavity  12 , in combination with the elasticity of the elastic portion  16 , defines a mold  10 ,  10 ′ having sufficient body material, strength and elasticity such that the filling of the mold and/or the pressurized demolding do not cause deformation of the cavity  12 , as occurs with a glove mold. Also, as described hereinabove, the mold of this invention is not designed to be peeled off from the icon, manually or otherwise, as is a glove mold.  
         [0024]    Although the demolding station  45  should not require that the mold have the pressure port  20  and be assisted by some positive pressure ejection, as provided by the ejection station  38 , certain icon designs and/or materials might benefit from ejection and mold expansion pressure provided by a combination of positive and negative pressure forces as provided by the demolding stations  42  and  45 .  
         [0025]    In the same way that the filling station  30  can be arranged to fill several molds at one time, as shown in FIG. 6, the vacuum station  45  can encompass several molds.  
         [0026]    Thereupon, the empty molds advance back toward the filling station  30  for further use. Before reaching the filling station, a specific mold or molds can be replaced with other icon producing molds.  
         [0027]    There can be more than one filling station, such as  30 ′ in FIG. 6, along the path of the conveyor belt  24 . Thus, if the cavity  12  is less than filled at the first filling station  30 , the cavity can be provided with a different layer of color and/or of substance at a second station  30 ′, to partially blend with or lie over the first filled substance. If needed, an additional cooling/hardening station can be positioned along the path of the belt  24 , subsequent to the second filling station  30 ′.  
         [0028]    Although FIGS.  5 - 7  describe a substantially fully automated system, the mold filling and/or demolding stations  30 ,  38  and  45  can be semi-manual, in that: the nozzle  34  can be hand held, with the hopper  32  being a source of pumpable icon material; the demolding pressure nozzle  42  be hand held directly against the pressure input port  20 ; and the demolding station  45 , with its vacuum chamber  46 , also can be hand held.  
         [0029]    It is believed that those skilled in the art will appreciate the scope of the invention from this Specification with its figures, and will be able to design variations, without departing from the scope of the invention, as defined by the appended claims.