Patent Publication Number: US-2012031145-A1

Title: Method of fabricating decoratively-cracked glass vessels

Description:
Priority based on Provisional Application Ser. No. 61/571,647 filed Jul. 2, 2011, and entitled “METHOD OF FABRICATING DECORATIVELY-CRACKED GLASS OBJECTS” is claimed. Priority is also claimed in Mexican Patent Aplication Folio No. MX/E/2010/048025 filed Aug. 4, 2010 and entitled ELABORACION DE BOTELLAS DE VIDRIO Y CRISTAL POR MEDIO DE LA TECNICA DE CRAQUELADO. The entirety of the disclosures of each of the previous applications, including the drawings, is incorporated herein by reference as if set forth fully in the present application. 
    
    
     BACKGROUND 
     The formation of glass into useful and artistic objects dates to at least the 4 th  Century BCE. Among the established techniques for forming glass are flow-molding, press-molding and hand-blowing. Hand-blown glass objects are admired for the artistry and skill required to produce them, and the uniqueness of each piece so produced. One effect traditionally produced by glass-blowing artisans is the inclusion of decorative cracks in finished products. The inclusion of such features signifies artistry, skill and uniqueness. However, the very nature of the hand-blowing process renders hand-blown pieces expensive and impractical for use as containers for all but the highest-end products such as fine perfumes and select alcoholic beverages. 
     Contrasting with the artistry associated with hand-blown glass objects is the rapid mass production of strictly utilitarian objects such as window panes and beverage bottles. Among the goals of manufacturing vessels such as drinking glasses and beverage bottles are rapid reproducibility and uniformity of appearance among units. Of particular importance is uniformity among units in physical dimensions such opening shape and size in order to facilitate the use of standardized lids, plugs or caps as closures. Accordingly, in the modern era, glass vessels are largely produced by strictly-controlled automated hot pressing and blowing processes. Such processes have the advantage of being relatively inexpensive and invariant, but result in products lacking uniqueness and artistry. 
     Accordingly, a need exists for a method of incorporating, within a glass object, and particularly a glass vessel, the unique feature of decorative cracks in a manner that facilitates ready and reliable reproducibility of predetermined physical dimensions. 
     SUMMARY 
     Implementations of the present invention are generally directed to a method of mass-producing consistently-dimensioned cracked-glass vessels incorporating decorative cracks while maintaining structural integrity. Although not so limited in scope, among the glass vessels of particular interest are drinking glasses, cups, bowls, decanters, vases, and selectively closeable bottles. 
     In accordance with an illustratively implemented method, an initial gob of molten glass is gathered. In a typical version, the molten-glass gob is removed from a glass furnace by gathering it about a distal end of an elongated gathering implement such as a rod, tube or gathering iron, by way of example. The molten-glass gob is introduced into a pre-form mold into which—in one implementation—a quantity of gas, such as air, by way of non-limiting example, is injected in order to form the gob into a pre-form vessel having at least one pre-form vessel wall defining a pre-form vessel exterior surface and a pre-form vessel interior surface defining a pre-form vessel cavity. The quantity of gas blown into the pre-form mold depends, in part, on the desired wall and base thicknesses of the vessel being formed. In various illustrative implementations, depending on the size and shape of the vessel being formed, the pre-form vessel remains in the pre-form mold for a period of between 2 and 5 seconds before it is removed and transferred for subsequent processing. 
     In one version, when the pre-form vessel is sufficiently cool and “self-supporting” to retain its basic shape, it is removed, while still hot, from the pre-form mold, and a surface of the same is exposed to a fluid that is sufficiently cool, relative to the pre-form vessel, that cracks are formed along the surface exposed to the fluid. In any particular implementation, an appropriate temperature differential between the pre-form vessel and the rapid-cooling fluid is a function of the glass type, pre-form vessel wall thickness and the specific heat of the fluid in question. In each case, the aforesaid temperature differential should be sufficiently large in magnitude to introduce the desired cracks, but not so large that the pre-form vessel experiences thermal shock that either shatters the pre-form vessel or introduces cracks too deep into the pre-form vessel wall. In some illustrative implementations, the fluid to which the pre-form vessel is exposed in order to crack it is a liquid, such as water. However, absent express limitations to the contrary in the appended claims, it is to be understood that the rapid-cooling fluid may be a liquid other than water or even a gas. In one illustrative version in which a liquid is used, a liquid temperature of 26-deg. Celsius is regarded as optimal. Additionally, in alternative versions, the surface of the pre-form vessel that is exposed to the rapid-cooling fluid is the exterior surface. 
     In a first illustrative version in which the desired crack effects have been introduced, the pre-form vessel is reheated such that the glass becomes sufficiently flowable that (i) cracks are sealed between the pre-form interior and exterior surfaces and (ii) the pre-form vessel can be reshaped. The reheated pre-form vessel is introduced into a finish mold. A quantity of gas is injected into the finish mold in order to form the pre-form vessel into a finished vessel having at least one finished vessel wall defining finished vessel interior and exterior surfaces between which cracks are visible and sealed. In a second illustrative version in which the desired crack effects have been introduced, the pre-form vessel is not reheated before finish molding. Instead, immediately after the introduction of cracks by exposure to a cooling fluid, the pre-form vessel is introduced into the finish mold where it is injected with air for a brief period of time (e.g., between 3 and 4 seconds). This finish molding step itself promotes the “sealing” of cracked areas internally from within the vessel, as long as the pre-form vessel is still sufficiently heated after cracking. 
     In some implementations, the pre-form and finish molds are actually the same physical mold which, when used in a “pre-forming” step is referred to as a “pre-form mold” and, when used in a “finish-molding” step is referred to as a “finish mold.” In fabricating a more complex glass vessel, such as a bottle including a neck, the use of physically distinct pre-form and finish molds facilitates intermediate shaping, thereby obviating logistical difficulties and diminished quality attendant to the use of a single mold at two different stages of the process in order to form of a shapeless gob into the final shape desired. Although the summation of the process to this point has implied molding in two stages, it will be generally appreciated that implementations prescribing more than two molding steps are also within the scope of the invention as defined in the claims. More specifically, even in implementations involving three or more molding steps, at least one such step (e.g., the first molding step) is regarded as a pre-forming step involving a pre-form mold, while at least one other step (i.e., the final molding step) is regarded as a finish molding step involving a finish mold. In at least one implementation described later in the present specification, a finish mold is used in intermediate and final molding steps. 
     Irrespective of whether the pre-form vessel is re-heated prior to finish molding, alternative implementations of the process prescribe heating of the cracked and finish-molded vessel or “finished vessel.” More specifically, the finished vessel is removed from the finish mold and permitted to cool for a brief period of time, typically between 2 and 4 seconds, for example. The finished vessel is then heated in order to seal the cracks on the exterior surface of the vessel while taking care not to re-melt the glass and perceptibly deform the shape of the finished vessel. In an illustrative implementation, the finished vessel is heated by a burner system in which burners torch the area of the vessel cracked by exposure to the cooling fluid. In various versions, the cracked regions are torched for between 3 and 6 seconds. However, as with the other time ranges presented as examples, this latter range should not be regarded as limiting the scope of the inventive process absent express limitations to the contrary in the claims appended hereto. 
     In alternative implementations, apparatus controlled by a programmable computer are variously utilized in the performance one or more steps. For instance, the use of a computer-controlled pneumatic injector is particularly useful in ensuring that the quantity and pressure of gas injected into the mold is appropriate, precise and selectively tunable. Additionally, at least one multi-piece mold can be opened and closed by computer-controlled pneumatics, hydraulics or motor-actuated linkages. While human involvement is integral to the implementation of some versions, particularly at the gob-gathering, cracking and heating stages—where an artisan&#39;s vision and skill might be desired—in alternative versions, even one or more of the steps prior to introduction of the gob into either the pre-form mold, or the introduction of the pre-form vessel into the finish mold, is performed by computer-controlled apparatus. 
     Representative, non-limiting implementations are more completely described and depicted in the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a gathered gob of molten glass being extracted from a glass furnace; 
         FIG. 2  shows the molten-glass gob of  FIG. 1  being deposited into a vessel-defining pre-form mold; 
         FIG. 3A  depicts the opened pre-form mold and the injection of gas to force the molten gob to assume a non-final shape defined by the pre-form mold, although the pre-form mold would not be open when gas is injected; 
         FIG. 3B  shows the non-finally-shaped pre-form vessel after removal from the pre-form mold; 
         FIG. 3C  depicts the non-finally-shaped pre-form vessel situated in an open finish mold; 
         FIG. 4  shows the finish mold of  FIG. 3C  in a closed position so that gas can be introduced to finalize the basic shape of the pre-form vessel of  FIGS. 3A-3C ; 
         FIG. 5  depicts the finish mold of  FIGS. 3C and 4  in an open position with the finally-shaped pre-form vessel still disposed therein; 
         FIG. 5A  illustrates the removal of the finally-shaped pre-form vessel of  FIG. 5  from the finish mold for transfer to subsequent processing; 
         FIG. 5B  shows the finally-shaped pre-form vessel of  FIGS. 5 and 5A  being at least partially immersed in a rapid-cooling fluid in order to introduce cracks in the pre-from vessel exterior surface; 
         FIG. 6  shows the cracked and finally-shaped pre-form vessel of  FIG. 5B  re-situated in the finish mold of  FIGS. 3C ,  4  and  5  so that the cracks can be sealed by the introduction of pressured gas into the interior of the pre-form vessel; 
         FIG. 7  depicts a finished vessel resulting from the crack-sealing step associated with  FIG. 6 ; 
         FIG. 7A  shows the finished vessel of  FIG. 7  being heated to facilitate crack sealing from the exterior of the vessel; 
         FIG. 8A  illustrates the formation of a glass gob into a non-finally shaped pre-form vessel in a pre-form mold, in much the same manner depicted in  FIG. 3A ; 
         FIG. 8B  illustrates the removal of the non-finally-shaped pre-form vessel of  FIG. 8A  from the pre-form mold for transfer to subsequent processing; 
         FIG. 8C  shows the non-finally-shaped pre-form vessel of  FIGS. 8A and 8B  being at least partially immersed in a rapid-cooling fluid in order to introduce cracks in the pre-from vessel exterior surface; and 
         FIG. 9  depicts how the cracked and non-finally-shaped pre-form vessel of  FIG. 8C  is reshaped into a finally-shaped finished vessel in a finish mold. 
     
    
    
     DETAILED DESCRIPTION 
     The following description of methods of fabricating a glass vessel with decorative cracks is demonstrative in nature and is not intended to limit the invention or its application of uses. The various implementations, aspects, versions and embodiments described in the summary and detailed description are in the nature of non-limiting examples falling within the scope of the appended claims and do not serve to maximally define the scope of the claims. 
     In conjunction with  FIGS. 1 through 9 , there are described alternative illustrative methods of fabricating a decoratively-cracked glass vessel. With initial reference to  FIG. 1 , a molten-glass gob  20  is gathered around the distal end  12  of an elongated gathering implement  10  and extracted from a furnace  15 . The gathering implement  10  is manipulated in order to give the initial gob  20  a generally ellipsoidal shape. 
     The illustrative implementations described with reference to  FIGS. 1 through 9  prescribe multi-stage molding processes, each of which includes, as shown in  FIG. 2 , the introduction of the molten-glass gob  20  into a pre-form mold  30 . With additional reference to  FIG. 3A , the illustrative pre-form mold  30  first shown in  FIG. 2  includes first and second mold portions  32  and  36  with, respectively, first and second interior walls  33  and  37 . When the first and second mold portions  32  and  36 —which are hingedly joined in the example depicted—are brought into mutual contact, the first and second interior walls  33  and  37  define an internal pre-shaping cavity  38 . In the illustrative version depicted, the pre-shaping cavity  38  is configured to define a pre-form vessel  50 . 
     With continued reference to  FIGS. 2 and 3A , with the molten-glass gob  20  deposited in the pre-form mold  30 , a pneumatic injector  200  injects a quantity of gas  210  into the pre-form mold  30  through an opening  39 . The internal gas pressure is elevated sufficiently to form the gob  20  into a pre-form vessel  50 . While the formation of the gob  20  into a pre-form vessel  50  is shown in  FIG. 3A  with the pre-form mold  30  depicted in an open position, this is only to facilitate explanation; it is to be understood that the introduction of gas  210  into the pre-form mold  30  actually occurs while the first and second mold portions  32  and  36  are in mutual contact (i.e., while the pre-form mold  30  is closed, as in  FIG. 2 ). 
     When the pre-form vessel  50  is sufficiently cool and “self-supporting” to retain its basic shape, the pre-form mold  30  is opened and the pre-form vessel  50  is removed, as shown in, respectively,  FIGS. 3A and 3B . The illustrative pre-form vessel  50  of  FIG. 3B  has a pre-form vessel wall  52  defining a pre-form vessel exterior surface  54  and a pre-form vessel interior surface  56  defining a pre-form vessel cavity  57 . In a first illustrative version, described initially with reference to  FIGS. 3A ,  3 B and  3 C, the heated pre-form vessel  50  is transferred from the pre-form mold  30  to a finish mold  70 . The illustrative finish mold  70  of  FIG. 3C  includes first and second mold pieces  72  and  76  having, respectively, first and second inside walls  73  and  77 . When the first and second mold pieces  72  and  76  are urged into mutual contact to seal the finish mold  70 , the first and second inside walls  73  and  77  define an internal finish-shaping cavity  78 . As shown in  FIG. 4 , in a manner analogous to that associated with shaping in the pre-form mold  30 , a quantity of gas  210  is injected into the finish mold  70 , and into the pre-form vessel cavity  57 , through a pneumatic injector  200  in order to impart to the pre-form vessel  50  its final basic shape. 
     Referring to  FIGS. 5 and 5A , after shaping in the finish mold  70 , the finish mold  70  is opened and the pre-form vessel  50  is removed. Although the vessel has been given its final basic shape, it is, in accordance with the implementation presently under consideration, still regarded as a pre-form vessel  50  because, as explained below, it is subjected to subsequent processing within the finish mold  70 . 
     With continued reference to  FIGS. 5 and 5A , and additional reference to  FIG. 5B , the aforementioned first version prescribes exposing at least one of the finally-shaped pre-form vessel exterior and interior surfaces  54  and  56  to a rapid-cooling fluid F RC  that is sufficiently cool relative to the pre-form vessel  50  that cracks  58  are formed along the surface exposed to the fluid F RC . For illustrative, non-limiting purposes,  FIG. 5B  shows the still-hot pre-form vessel  50  of  FIGS. 5 and 5A  being immersed in a reservoir of cool water W C  in order to form cracks  58  in the pre-form vessel exterior surface  54 . As stated in the summary, however, it will be appreciated that the rapid-coiling fluid F RC  need not be water, or even a liquid; a cold gas may be alternatively implemented as the fluid F RC . It is also to be understood that, while the example of  FIG. 5B  shows the pre-form vessel exterior surface  54  being cracked, the pre-form vessel interior surface  56  could be cracked by introduction of fluid F RC  into the pre-form vessel cavity  57 . However, experimentation has indicated that cracking from the exterior surface  54  less difficult and generally yields superior results. In various implementations, the cracks  58  extend through nearly the entire thickness of the pre-form wall  52 . 
     With reference to  FIG. 6 , the now-cracked pre-form vessel  50  of  FIG. 5B  is, while heated, re-introduced into the finish mold  70 . The finish mold  70  is then closed and gas  210  is injected in the manner shown in  FIG. 4 . Subjecting the perform vessel  50  to elevated internal gas pressure in this final “molding” step facilitates the “sealing” of cracks  58  from within the interior of the vessel. More specifically, while the cracks  58  remain visible, the elevated pressure exerted by the gas  210  within the pre-form vessel cavity  57  causes the movement (flow) of still-heated glass outwardly toward the pre-form vessel exterior surface  54  between “islands”  59  of glass defining the cracks  58 . When the glass “flowably forced” into the cracks  58  from the vessel interior cools, it fuses and increases structural integrity, while maintaining the visibility of the cracks  58 . It will be appreciated that this final “molding” step in the version currently under consideration is more in the nature of a crack-sealing step, as the pre-form vessel  50  will undergo little, if any, shape redefining at this stage. 
     After sealing in the finish mold  70 , the pre-form vessel  50  has been transformed into what is regarded as a “finished vessel” It will be appreciated, particularly in implementations involving more than two “molding” stages, that the designation of a work-piece as either a “pre-form vessel” or a “finished vessel” can be somewhat arbitrary. This is particularly the case when, for example, a finish mold (e.g., finish mold  70 ) is used in more than one step since the final basic shape is imparted to the vessel prior to the final “molding” step. However, in an effort to lend a measure of clarity to the description, a vessel undergoing processing is regarded as a “pre-from vessel” up until the point that is treated for the last time in a mold. More specifically, upon introduction into a finish mold for the final time, a vessel is referred to as a “pre-form vessel” and, upon removal from that mold for the last time, it is regarded as a “finished vessel.” 
     An example of a finished vessel  80  is shown in  FIG. 7 . The finished vessel  80  has at least one vessel wall  82  defining finished vessel exterior and interior surfaces  84  and  86  between which cracks  58  are visible and at least partially sealed. 
     Referring to  FIG. 7A , in some versions, the finished vessel  80 , after removal from the finish mold  70 , is allowed to cool for a predetermined duration (e.g. between 2 and several seconds). The finished vessel  80  is then heated in order to seal the cracks  58  on the vessel exterior surface  84  while measures are taken not to re-melt the glass and perceptibly deform the shape of the finished vessel  80 . In an illustrative implementation, the finished vessel  80  is heated by a burner system  300  in which one or more burners torch the area of the vessel  80  cracked by exposure to the cooling fluid F RC . In  FIG. 7A , the burner system  300  is represented by a torch  310  for purposes of non-limiting illustration. 
     A second illustrative version tracks the initial steps of the first illustrative version described above in conjunction with  FIGS. 1 through 3B . However, whereas the first illustration version calls for the pre-form vessel  50  to be transferred directly from a pre-form mold  30 , in which it is given a non-final configuration, to a finish mold  70 , in which it is given its final basic shape, the second version differs by prescribing intermediate cracking prior to final shaping. More specifically, and with initial reference to  FIGS. 8A ,  8 B and  8 C, at least one of the non-finally-shaped (or “intermediately-shaped”) pre-form vessel exterior and interior surfaces  54  and  56  is exposed to a rapid-cooling fluid F RC  that is sufficiently cool relative to the pre-form vessel  50  that cracks are formed along the surface exposed to the fluid F RC . For illustrative, non-limiting purposes,  FIG. 8C  shows the still-hot pre-form vessel  50  of  FIGS. 8A and 8B  being immersed in a reservoir of cool water W C  in order to form cracks  58  in the pre-form vessel exterior surface  54 . 
     Following the introduction of cracks  58  along at least one pre-form wall  52 , in a first implementation in which the non-finally-shaped pre-form vessel  50  is cracked, the pre-form vessel  50  is reheated in order to (i) fuseably seal the cracks  58  under a continuous “skin” of glass between the pre-form interior and exterior surfaces  56  and  54  and (ii) render the pre-form vessel  50  sufficiently soft for additional shaping. It will be appreciated that the reheating of the pre-form vessel  50  involves a balance of mutually competitive objectives. In accordance with one set of objectives, the pre-form vessel  50  is heated sufficiently to facilitate “sealing over” of the cracks  58  and refined shaping. However, a second set of objectives indicates that the pre-form vessel  50  not be heated to such an extent that the cracks  58  are lost through complete re-fusion of glass through the entire thickness of the pre-form wall  52  or such that the pre-form vessel  50  loses too much of its shape. In a second implementation in which the non-finally-shaped pre-form vessel  50  is cracked, the vessel  50  is not re-heated prior to subsequent processing. It will be appreciated, however, that the pre-form vessel  50  must still be sufficiently hot for final shaping in general accordance with the steps described below. In illustrative cases in which the pre-form vessel  50  is reheated, it is introduced into a furnace, such as furnace  15  in  FIG. 1 , or heated by a burner  300  or torch  310 , as shown in  FIG. 7A . It will be appreciated that the method of re-heating is of no particular importance. 
     Irrespective of whether the cracks  58  are sealed over by re-heating, the cracked and non-finally-shaped pre-form vessel  50 , while still sufficiently heated for shape refinement, is situated within a finish mold  70 . As with the finish mold  70  of  FIG. 3C , the illustrative finish mold  70  of  FIG. 9  includes first and second mold pieces  72  and  76  having, respectively, first and second inside walls  73  and  77 . When the first and second pieces  72  and  76  are urged into mutual contact, the first and second inside walls  73  and  77  define an internal finish-shaping cavity  78 . As in  FIG. 4 , a quantity of gas  210  is injected into the finish mold through a pneumatic injector  200  in order to form the pre-form vessel  50  into a finished vessel  80 . More specially, as indicated in  FIGS. 8C and 9 , the vessel is a non-finally-shaped pre-form vessel  50  when it is placed into the finish mold  70  and, when the vessel emerges from this final molding step, it is a finally-shaped finished vessel  80 . As in the case of the first major implementation, a finished vessel  80  fabricated in accordance with the present implementation can be heated as shown in  FIG. 7A , for example, in order to seal the cracks  58  on the vessel exterior surface  84 . 
     As previously explained, alternative implementations involve the use of either (i) a single mold in temporarily separate “pre-forming” and “finish-molding” steps or (ii) two or more physically distinct molds in “pre-forming” and “finish-molding” steps. As a general observation, more intricate final products call for molding in at least two stages with at least two physically distinct molds. For instance, while the formation of a vessel such as a drinking cup might be pre-formed and finish molded in a single physical mold, a vessel such as a bottle might call for physically distinct pre-form and a finish molds. The illustrative finished vessels  80  of  FIGS. 6 ,  7 ,  7 A and  9  are bottles  90 , each of which, as shown in  FIG. 7 , has a main body  92  defining an internal storage cavity  94  and a neck  96  depending from the body  92 . The neck  96  is narrow relative to the main body  92  and has a neck opening  98  (or channel) extending therethrough that renders the storage cavity  94  in fluid communication with the exterior of the bottle  90 . It will be appreciated that the formation of a relatively narrow neck  96  might best be performed in a multi-stage molding process with at least two physically distinct molds. This is particularly true when the neck  96  and the neck opening  98  must be fabricated within “tight” or relatively unforgiving tolerances, as when the bottles  90  being produced are to be sealed by standardized closures such as caps or plugs (not shown). 
     The foregoing is considered to be illustrative of the principles of the invention. Furthermore, since modifications and changes to various aspects and implementations will occur to those skilled in the art without departing from the scope and spirit of the invention, it is to be understood that the foregoing does not limit the invention as expressed in the appended claims to the exact constructions, implementations and versions shown and described.