Patent Publication Number: US-6981861-B2

Title: Foaming mold using hollow tubes

Description:
RELATED APPLICATIONS 
   The present disclosure relates to subject matter contained in Korean Application No. 10-2003-0062590, filed on Sep. 8, 2003, which is herein expressly incorporated by reference its entirety. 
   BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The present invention relates to a foaming mold using hollow tubes, and more particularly, to an improved mold for use in manufacturing a foamed product through foaming (or expansion molding), in which gas generated from the foamed product during the foaming can be smoothly discharged to the outside, thereby improving the quality of the final foamed product. 
   2. Description of the Prior Art 
   Generally, a foamed product is a product having a specific configuration desired by an operator, which is obtained by injecting a liquid foaming material into a mold having a cavity engraved in conformity with the desired configuration, and foaming and curing the liquid foaming material within the mold. The curing of the liquid foaming material into the foamed product can proceed or be facilitated by maintaining an atmosphere for the liquid foaming material within a specific temperature range or by adding chemical additives to the liquid foaming material. 
   Further, as for such a foamed product, it is possible to obtain a molded product comprising only a foam made through the curing of a liquid foaming material by filling a mold with only the liquid foaming material, curing the liquid foaming material and removing the mold. Alternatively, it is also possible to obtain a molded product into which a skin, a core and a foam such as a urethane pad made through the curing of a liquid foaming material are integrally incorporated by stacking the skin and core in a mold, filling the liquid foaming material between the skin and the core and curing the liquid foaming material. 
   Particularly, a vehicle instrument panel is a typical example of a molded product comprising a skin, a core and a foam pad as in the latter. 
   To produce such a molded product comprising a foam, when a liquid foaming material is injected into a mold, a sealing structure capable of preventing the leakage of the injected liquid foaming material from the mold is further required. Further, in order to obtain a good quality of a molded product comprising a foam made through foaming, there is a need for a degassing process by which gas generated while a liquid foaming material is cured into the foam during the foaming is discharged to the outside of the mold. 
     FIG. 1  is a sectional view showing a conventional foaming mold, and  FIG. 2  is a sectional view illustrating a degassing process in the conventional foaming mold. 
   As shown in  FIGS. 1 and 2 , the conventional foaming mold comprises a mold unit  10  including separate first and second half molds  11  and  12  with inner cavities engraved in conformity with the configuration of a molded product  30 ; and a resilient sealing projection  20  fixed between the first and second half molds  11  and  12  of the mold unit  10  to enclose an outer periphery of the configuration of the molded product  30 . 
   As shown in  FIG. 1 , the conventional foaming mold thus constructed is provided with the mold unit  10  including the first and second half molds  11  and  12  that have the cavities engraved in conformity with the configuration of the molded product  30  and are stacked one above another. Between the first and second half molds  11  and  12 , the resilient sealing projection  20  having a circular cross section, for example, is fixed to and protrudes from one of the half molds while enclosing the outer periphery of the configuration of the molded product  30 . Accordingly, when a liquid foaming material is injected into the mold unit  10 , the foaming material is prevented from leaking out from the mold unit  10 . 
   In order to produce the final molded product  30  comprising the skin  31 , the core  32  and the pad  33  through the foaming using the conventional foaming mold described above, the core  32  and the skin  31  are stacked one above another between the first and second half molds  11  and  12 , a liquid foaming material such as urethane is injected and cured between the core  32  and the skin  31 , and the injected foaming material is molded into the pad  33  as a foam. Thus, the pad  33  is integrally combined with the core  32  and the skin  31  to form the final molded product  30 . 
   Thus, a manufacturer can obtain the final molded product  30  comprising the foam having a desired configuration by means of the mold unit  10  provided with the sealing projection  20 . 
   In performing the foaming using the conventional foaming mold, the degassing process of discharging gas, which is generated from the foam upon curing the liquid foaming material, to the outside of the mold is required during the foaming in order to prevent the deterioration of the quality of the product due to the presence of the remaining gas in the molded product  30 , as shown in FIG.  2 . 
   However, since the conventional foaming mold is not provided with an additional means for discharging the gas generated from the foam to the outside of the mold, the gas is discharged from the foam merely by causing two half molds to be spaced apart by a predetermined distance from each other. If the degassing is performed over an entire surface of the foam in such a manner at once, there are problems in that the efficiency of degassing is lowered and thus the quality of the foam is not uniform, whereby the resultant quality of the final molded product is deteriorated. 
   SUMMARY OF THE INVENTION 
   The present invention is conceived to solve the aforementioned problems. An object of the present invention is to provide a foaming mold using hollow tubes, wherein gas generated from a foam molded in a mold during foaming is smoothly discharged to the outside of the mold locally from respective regions partitioned in the mold, thereby improving the quality of a final molded product obtained through the foaming. 
   According to the present invention for achieving the object, there is provided a foaming mold using hollow tubes, comprising a mold unit including separate first and second half molds having inner cavities engraved in conformity of a molded product; the plurality of hollow tubes that are isolated and sealed from one another in respective regions and located between the first and second half molds to enclose an outer periphery of the configuration of the molded product; and a plurality of vents that are formed within the second half mold to communicate with the hollow tubes so that air in the isolated hollow tubes can be independently vented. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and features of the present invention will become apparent from the following description of a preferred embodiment given in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a sectional view showing a conventional foaming mold; 
       FIG. 2  is a sectional view illustrating a degassing process in the conventional foaming mold; 
       FIG. 3  is a front sectional view of an embodiment of a foaming mold using hollow tubes according to the present invention; 
       FIG. 4  is a partial sectional plan view showing a second mold and the hollow tubes in the embodiment of the foaming mold using the hollow tubes according to the present invention; and 
       FIG. 5  is a front sectional view illustrating a degassing process in the embodiment of the foaming mold using the hollow tubes according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
     FIG. 3  is a front sectional view of an embodiment of a foaming mold using hollow tubes according to the present invention,  FIG. 4  is a partial sectional plan view showing a second mold and the hollow tubes in the embodiment of the foaming mold using the hollow tubes according to the present invention, and  FIG. 5  is a front sectional view illustrating a degassing process in the embodiment of the foaming mold using the hollow tubes according to the present invention. 
   As shown in  FIGS. 3  to  5 , in the embodiment, the foaming mold using the hollow tubes according to the present invention comprises a mold unit  100  including separate first and second half molds  110  and  120  having inner cavities engraved in conformity with a molded product  400 ; the plurality of hollow tubes  200  that are isolated and sealed from one another in respective regions and located between the first and second half molds  110  and  120  to enclose an outer periphery of the configuration of the molded product  400 ; and a plurality of vents  300  that are formed within the second half mold  120  to communicate with the hollow tubes  200  so that air in the isolated hollow tubes  200  can be independently vented. 
   Here, the mold unit  100  may be used for producing the molded product  400 , such as a vehicle instrument panel that comprises a pad  430  as a foam made of urethane, a skin  410  and a core  420 . 
   The operation of the foaming mold according to the present invention will be described with reference to  FIGS. 3  to  5 . 
   As shown in  FIGS. 3 and 4 , in the embodiment of the foaming mold using the hollow tubes according to the present invention, the foaming mold is provided with the mold unit  100  including the first and second half molds  110  and  120  that have the cavities engraved in conformity with the configuration of the molded product  400  and are stacked one above another. Between the first and second half molds  110  and  120  of the mold unit  100 , the hollow tubes  200  that, for example, are made of a resilient material and have a circular cross section are fixed to enclose the outer periphery of the molded product  400 . 
   At this time, as shown in  FIG. 4 , the hollow tubes  200  are properly isolated from one another in a plurality of regions on the second half mold  120 . Preferably, the lower half of each hollow tube  200  is fixedly embedded in the second half mold  120 , and at least one vent  300  extending toward a lower portion of the second half mold  120  is formed to communicate with each of the hollow tubes  200 . 
   Therefore, an operator can selectively inject air into or discharge air from the hollow tubes  200  through the vents  300  so that the hollow tubes  200  can be filled with the air and then inflated, or contracted by means of the discharge of the air from the hollow tubes  200 . 
   When the hollow tubes  200  are inflated by injecting the air through the vents  300 , the inflated hollow tubes  200  prevent a liquid foaming material, which has been injected into the mold unit  100 , from leaking out between the first and second half molds  110  and  120 , as shown in FIG.  3 . On the contrary, when the hollow tubes  200  are contracted by discharging the air through the vents  300  as shown in  FIG. 5 , gas generated from a foam obtained through the curing of the foaming material can be easily discharged through a gap created due to the contraction of the hollow tubes  200  and a space between the first and second half molds  110  and  120 . 
   To produce the final molded product  400  comprising the skin  410 , the core  420 , and the pad  430  through the foaming using the foaming mold using the hollow tubes according to the present invention, the core  420  and the skin  410  are first stacked one above another between the first and second half molds  110  and  120 . Thereafter, the liquid foaming material such as urethane is injected and cured between the core  420  and the skin  410 . Then, the injected foaming material such as urethane is molded into the pad  430  as a foam through the foaming. The foam pad  430  is integrally combined with the core  420  and the skin  410  to form the final molded product  400  such as a vehicle instrument panel. 
   At this time, upon molding the molded product  430  through the foaming, a degassing process is performed to prevent gas generated during the curing of the foaming material from being captured in the foam pad  430  of the molded product  430 . Upon performing the foaming using the foaming mold according to the present invention, the gas generated from the foam of the molded product  400  can be easily discharged to the outside of the mold unit  100  by contracting the hollow tubes  200  using the hollow tubes  200  and the vents  300  of the second half mold  120 , which are additionally provided in accordance with the present invention, to create a gap between the first and second half molds  110  and  120 . 
   The degassing process of discharging the gas from the foam (i.e., pad  430 ) of the molded product  400  through the foaming mold according to the present invention will be explained in detail with reference to the accompanying drawings. 
   When the liquid foaming material is intended to be injected into the mold unit  100  including the first and second half molds  110  and  120 , air is first injected into all the hollow tubes  200 , which are fixed to the second half mold  120  to enclose the outer periphery of the configuration of the molded product  400 , through the vents  300  to inflate the hollow tubes  200 . 
   Thereafter, the core  410  and the skin  420  are stacked one above another between the first and second half molds  110  and  120 , and the foaming material is injected therebetween. 
   At this time, the foaming material injected into the mold unit  100  as such is prevented from leaking out between the core  410  and the skin  420  by means of the inflated hollow tubes  200 , as shown in  FIG. 3 , and is then foamed and cured therein to mold the foam. 
   After a predetermined period of time passes, the operator discharges air from one of the inflated hollow tubes  200  through the relevant vent  300 . Accordingly, the hollow tube  200  from which the air is discharged is contracted and the gas generated from the foam escapes through the gap created due to the contraction of the hollow tube  200  and the space between the first and second half molds  110  and  120 . 
   For example, in a case where four hollow tubes  200  are provided in the mold unit  100  to enclose the outer periphery of the configuration of the molded product  400  as shown in  FIG. 4 , if air is discharged from the right hollow tube  200  in the figure through the relevant vent  300 , only the right hollow tube  200  is contracted and thus a gap is created between the first and second half molds  110  and  120 , as shown in FIG.  5 . Accordingly, only gas remaining in a right region of the resultant foam of the molded product  400  locally escapes through the created gap. 
   Then, such a degassing process is sequentially performed with respect to the remaining hollow tubes  200 , so that gas generated from the molded product  400  comprising the foam can be effectively discharged, through gaps created due to the contraction of the hollow tubes  200 , locally from respective regions, e.g., upper and lower regions, and right and left regions. Thus, it is possible to prevent the deterioration of the quality of the molded product  400 , which occurs when the gas is discharged from the entire surface of the molded product  400  at once in the prior art. 
   According to the foaming mold of the present invention, the gas generated from the resultant foam during the foaming can be easily discharged locally from the respective regions of the mold unit  100  through the gaps between the first and second half molds  110  and  120  created by using the additional hollow tubes  200  and vents  300 . Thus, there is an advantage in that the degassing process can be effectively performed, thereby obtaining the good quality of the final molded product  400 . 
   As described above, the present invention improves the quality of the final molded product obtained through the foaming by smoothly discharging the gas generated from the foam molded in the mold during the foaming, to the outside of the mold locally from respective regions partitioned in the mold.