Abstract:
A method of forming a blow molded plastic article wherein the article comprises an airflow conduit, comprising: providing a first sheet of insulation material located on a insulation carrier; providing a blow molding mold including two halves and having a molding surface defining a molding cavity to form the article; locating the insulation carrier between the two halves of the blow molding mold; transferring the first sheet of insulation material from the insulation carrier to the blow molding mold; introducing an extrudate of thermoplastic composition between the two halves of the blow molding mold; closing the blow molding mold; forming the extrudate to a shape of the mold cavity of the blow molding mold to form the article; and bonding the extrudate to the first sheet of insulation material as the extrudate is being formed to the shape of the mold cavity.

Description:
FIELD 
       [0001]    The present disclosure relates in general to airflow conduits, and more particularly to a blow molded airflow conduit for a motor vehicle, which includes outer insulation to increase thermal efficiency and/or noise attenuation characteristics of the blow molded airflow conduit. 
       BACKGROUND 
       [0002]    Airflow conduits within motor vehicles may be used to circulate air as part of the heating, ventilation and air-conditioning (HVAC) system. The airflow conduits may be used to circulate heated or cooled air to various locations within the motor vehicle. For example, exemplary airflow conduits may be arranged beneath the instrument panel, center console, the floor carpet or the roof headliner. Such airflow conduits may direct airflow towards the windshield, footwells, seats and otherwise throughout the passenger compartment. The air may be fresh (ambient) air from outside of the vehicle, recirculated air from within the vehicle or a combination thereof. 
         [0003]    Airflow conduits may be blow molded from a thermoplastic composition. While blow molded airflow conduits are relatively inexpensive to produce, the blow molded airflow conduits may exhibit certain drawbacks. 
         [0004]    The blow molded airflow conduits may suffer from relatively low thermal efficiency, such that the heated or cooled air being transmitted therein may substantially decrease or increase in temperature, respectively, before the air reaches the passenger compartment. The blow molded airflow conduit may also vibrate and/or contact against other motor vehicle components during operation of the vehicle, which may result in squeaking, rattling or other unwanted noise. 
         [0005]    In order to reduce unwanted noise with adjacent components, a localized foam element may be glued onto the blow molded airflow conduit at a location indicative of the source of unwanted noise, such as at a location where the blow molded airflow conduit may make contact with another component (e.g. rub against) when the vehicle is being operated. 
         [0006]    In order to increase thermal efficiency, particularly at the inlet and/or outlet to the blow molded airflow conduit where the conduit may mate with another component, the mating edge of the blow molded airflow conduit may include a localized foam seal intended to seal the connection formed between the mating components to inhibit airflow losses. Similar to the foam element used for noise attenuation, the foam seal may be glued to the blow molded thermoplastic airflow conduit with a separate adhesive. In both instances, the adhesive may be a hot-melt adhesive or a pressure sensitive adhesive. 
         [0007]    Unfortunately, while the use of a foam seal particularly only at locations where the blow molded airflow conduit mates with other components may reduce airflow losses, such does not address the thermal losses encountered by air as it flows along the length of the blow molded airflow conduit. 
         [0008]    Furthermore, the use of an adhesive to glue the foam seal or other foam element to the blow molded airflow conduit is problematic, in that the bond may degrade over time and ultimately fail. 
       SUMMARY 
       [0009]    The present disclosure provides airflow conduits, and more particularly a blow molded airflow conduit which may include outer insulation to increase thermal efficiency and/or noise attenuation characteristics of the blow molded airflow conduit, which may include, for example, noise suppression and/or noise absorption. 
         [0010]    The thermal and/or sound insulation is attached to the blow molded airflow conduit during the blow molding process, such that the insulation is directly bonded to the blow molded airflow conduit without a need for separate adhesive to bond the insulation thereto. 
         [0011]    Furthermore, the blow molding process enables a substantial portion of the blow molded airflow conduit to be covered with thermal and/or sound insulation, thus increasing the thermal efficiency of the blow molded airflow conduit, as well as noise attenuation. 
         [0012]    In at least one embodiment of the disclosure, a method of forming a blow molded plastic article is provided, with the method comprising providing an insulation carrier; providing a first sheet of insulation material located on the insulation carrier; providing a blow molding mold, the blow molding mold including two halves and having a molding surface defining a molding cavity to form the blow molded plastic article, wherein the blow molded plastic article comprises a blow molded airflow conduit; locating the insulation carrier between the two halves of the blow molding mold; transferring the first sheet of insulation material from the insulation carrier to the blow molding mold such that the first sheet of insulation material overlies at least a first portion of the molding surface of the blow molding mold; introducing an extrudate of thermoplastic composition between the two halves of the blow molding mold; closing the blow molding mold; forming the extrudate to a shape of the mold cavity of the blow molding mold to form the blow molded plastic article; bonding the extrudate to the first sheet of insulation material overlying at least a portion of the mold surface of the blow molding mold as the extrudate is being formed to the shape of the mold cavity; and forming at least one air inlet and at least one air outlet in the blow molded airflow conduit. 
         [0013]    In at least one embodiment of the disclosure, the first sheet of insulation material is retained on the insulation carrier by vacuum. 
         [0014]    In at least one embodiment of the disclosure, the insulation carrier comprises a first insulation carrying mandrel; and providing a first sheet of insulation material located on the insulation carrier further comprises forming the first sheet of insulation material on the first insulation carrying mandrel. 
         [0015]    In at least one embodiment of the disclosure, forming the first sheet of insulation material on the first insulation carrying mandrel further comprises vacuuming forming the first sheet of insulation material on the first insulation carrying mandrel. 
         [0016]    In at least one embodiment of the disclosure, forming the first sheet of insulation material on the first insulation carrying mandrel further comprises forming the first sheet of insulation material on the first insulation carrying mandrel from a first planar sheet of insulation material to a first three-dimensional preform of a first portion of the blow molded airflow conduit. 
         [0017]    In at least one embodiment of the disclosure, forming the first sheet of insulation material on the first insulation carrying mandrel is performed after heating the first sheet of insulation material. 
         [0018]    In at least one embodiment of the disclosure, transferring the first sheet of insulation material from the insulation carrier to the blow molding mold includes moving at least one of the blow molding mold halves towards the insulation carrier; providing the at least one blow molding mold half which moves towards the insulation carrier with vacuum; and using the vacuum of the at least one blow molding mold half which moves towards the insulation carrier to remove the first sheet of insulation material from the insulation carrier and retain the first sheet of insulation material on the at least one blow molding mold half of the blow mold. 
         [0019]    In at least one embodiment of the disclosure, transferring the first sheet of insulation material from the insulation carrier to the blow molding mold includes moving the insulation carrier towards at least one of the blow molding halves; providing the at least one blow molding mold half which the insulation carrier moves towards with vacuum; and using the vacuum of the at least one blow molding mold half which the insulation carrier moves towards to remove the first sheet of insulation material from the insulation carrier and retain the first sheet of insulation material on the at least one blow molding mold half. 
         [0020]    In at least one embodiment of the disclosure, the method may further comprise providing a second sheet of insulation material located on the insulation carrier. 
         [0021]    In at least one embodiment of the disclosure, the second sheet of insulation material is retained on the insulation carrier by vacuum. 
         [0022]    In at least one embodiment of the disclosure, the insulation carrier comprises a first insulation carrying mandrel and a second insulation carrying mandrel; and providing a first sheet of insulation material located on the insulation carrier further comprises forming the first sheet of insulation material on the first insulation carrying mandrel; and 
         [0023]    providing a second sheet of insulation material located on the insulation carrier further comprises forming the second sheet of insulation material on the second insulation carrying mandrel. 
         [0024]    In at least one embodiment of the disclosure, forming the first sheet of insulation material on the first insulation carrying mandrel further comprises vacuuming forming the first sheet of insulation material on the first insulation carrying mandrel; and forming the second sheet of insulation material on the second insulation carrying mandrel further comprises vacuuming forming the second sheet of insulation material on the second insulation carrying mandrel. 
         [0025]    In at least one embodiment of the disclosure, forming the first sheet of insulation material on the first insulation carrying mandrel further comprises forming the first sheet of insulation material on the first insulation carrying mandrel from a first planar sheet of insulation material to a first three-dimensional preform of at least a first portion of the blow molded airflow conduit; and forming the second sheet of insulation material on the second insulation carrying mandrel further comprises forming the second sheet of insulation material on the second insulation carrying mandrel from a second planar sheet of insulation material to a second three-dimensional preform of at least a second portion of the blow molded airflow conduit. 
         [0026]    In at least one embodiment of the disclosure, forming the first sheet of insulation material on the first insulation carrying mandrel is performed after heating the first sheet of insulation material; and forming the second sheet of insulation material on the second insulation carrying mandrel is performed after heating the second sheet of insulation material. 
         [0027]    In at least one embodiment of the disclosure, transferring the second sheet of insulation material from the insulation carrier to the blow molding mold such that the second sheet of insulation material overlies at least a second portion of the molding surface of the blow molding mold. 
         [0028]    In at least one embodiment of the disclosure, transferring the first sheet and the second sheet of insulation material to the blow molding mold includes moving the blow molding mold halves towards the insulation carrier; providing each blow molding mold half with vacuum; using the vacuum of one of the blow molding mold halves to remove the first sheet of insulation material from the insulation carrier and retain the first sheet on the one blow molding mold half of the blow mold; and using the vacuum of the other of the blow molding mold halves to remove the second sheet of insulation from the insulation carrier and retain the second sheet on the other blow molding mold half of the blow mold. 
         [0029]    In at least one embodiment of the disclosure, transferring the first sheet and the second sheet of insulation material to the blow molding mold includes moving the insulation carrier towards each of the blow mold halves; providing each blow molding mold half with vacuum; using the vacuum of one of the blow molding mold halves to remove the first sheet of insulation material from the insulation carrier and retain the first sheet on the one blow molding mold half of the blow mold; and using the vacuum of the other of the blow molding mold halves to remove the second sheet of insulation from the insulation carrier and retain the second sheet on the other blow molding mold half of the blow mold. 
         [0030]    In at least one embodiment of the disclosure, bonding the extrudate to the second sheet of insulation material overlying at least a second portion of the mold surface of the blow molding mold as the extrudate is being formed to the shape of the mold cavity. 
         [0031]    In at least one embodiment of the disclosure, the first sheet of insulation material forms an exposed outer layer of the blow molded airflow conduit. 
         [0032]    In at least one embodiment of the disclosure, the extrudate forms at least one inner layer beneath the outer layer of the blow molded airflow conduit; and the at least one inner layer defines an airflow passage of the blow molded airflow conduit. 
     
    
     
       FIGURES 
         [0033]    The above-mentioned and other features of this disclosure, and the manner of attaining them, will become more apparent and better understood by reference to the following description of embodiments described herein taken in conjunction with the accompanying drawings, wherein: 
           [0034]      FIG. 1  is a perspective view of a blow molded airflow conduit according to the present disclosure; 
           [0035]      FIG. 2  is a cross-sectional view of the blow molded airflow conduit taken in the direction of line  2 - 2  of  FIG. 1 ; 
           [0036]      FIG. 3  is a cross-sectional view of an insulation carrier and planar sheets of insulation material, with the cross-sectional view taken in the direction of line  2 - 2  of  FIG. 1 ; 
           [0037]      FIG. 4  is a cross-sectional view of the insulation carrier and preformed sheets of insulation material on the insulation carrier, with the cross-sectional view taken in the direction of line  2 - 2  of  FIG. 1 ; 
           [0038]      FIG. 5  is a cross-sectional view of the preformed sheets of insulation material on the insulation carrier within the confines of an opened blow mold, with the cross-sectional view taken in the direction of line  2 - 2  of  FIG. 1 ; 
           [0039]      FIG. 6  is a cross-sectional view of the preformed sheets of insulation material on the insulation carrier within the confines of the blow mold after the blow mold has been closed, with the cross-sectional view taken in the direction of line  2 - 2  of  FIG. 1 ; 
           [0040]      FIG. 7  is a cross-sectional view of the preformed sheets of insulation material in the blow mold, which has been opened, and an extrudate in the form of an unblown parison (with the distal end of the parison open) within the confines of the blow mold, with the cross-sectional view taken in the direction of line  2 - 2  of  FIG. 1 ; 
           [0041]      FIG. 8  is a cross-sectional view of the preformed sheets of insulation material in the blow mold, which has been closed, and the extrudate/parison expanded (blown) to the shape of the blow molded airflow conduit and bonded to the preformed sheets of insulation material, with the cross-sectional view taken in the direction of line  2 - 2  of  FIG. 1 ; 
           [0042]      FIG. 9  is a cross-sectional view of the blow molded airflow conduit taken in the direction of line  2 - 2  of  FIG. 1 , taken after trimming and forming an airflow inlet and an airflow outlet therein; 
           [0043]      FIG. 10  is a cross-sectional view of the preformed sheets of insulation material in the blow mold, which is opened, and an extrudate in the form of an unblown parison (with the distal end of the parison closed) within the confines of the blow mold, with the cross-sectional view taken in the direction of line  2 - 2  of  FIG. 1 ; 
           [0044]      FIG. 11  is a cross-sectional view of the preformed sheets of insulation material on a second embodiment of the insulation carrier, within the confines of the opened blow mold, with the insulation carrying mandrels retracted, and with the cross-sectional view taken in the direction of line  2 - 2  of  FIG. 1 ; and 
           [0045]      FIG. 12  is a cross-sectional view of a the preformed sheets of insulation material on the second embodiment of the insulation carrier, within the confines of the opened blow mold, with the insulation carrying mandrels extended, and with the cross-sectional view taken in the direction of line  2 - 2  of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0046]    It may be appreciated that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention(s) herein may be capable of other embodiments and of being practiced or being carried out in various ways. Also, it may be appreciated that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting as such may be understood by one of skill in the art. 
         [0047]    Referring to  FIGS. 1 and 2 , there is shown a molded plastic article  10  according to the present disclosure, and more particularly an exemplary blow molded plastic article in the form of an elongated airflow conduit. The molded plastic article  10  may comprise an exposed outer (thermal and/or sound) insulation layer  30 , and an inner substrate layer  20 , which defines an airflow passage  12  of the conduit, beneath the outer insulation layer  30 . 
         [0048]    Referring now to  FIG. 3 , molded plastic article  10  may be formed by first shaping the outer insulation layer  30 . Outer insulation layer  30  may be formed in a three-dimensional shape, from one or more sheets of insulating material  40   a,    40   b  which may be planar (i.e. two-dimensional), such as flat blanks cut from roll-stock. 
         [0049]    As shown, two sheets of insulating material  40   a,    40   b  are used to form the outer insulation layer  30 , with the sheets of insulating material  40   a,    40   b  arranged to be on opposing sides of the molded plastic article  10  after it is formed. The sheets of insulating material  40   a,    40   b  may be held in perimeter retention frames  100  and heated with a heating source  110 , such as an infrared heater, on one or both sides thereof. 
         [0050]    Thereafter, heating source  110  may be removed, and the sheets of insulating material  40   a,    40   b  may be moved towards a first tool  200  centrally located there between. However, it should be understood that heating of the sheets of insulating material  40   a,    40   b  prior to forming may not be required in all instances, and will depend on the composition of the insulating material  40   a,    40   b,  as well as the geometry of the molded plastic article  10 . 
         [0051]    As shown, first tool  200  may comprise insulation carrier  204  which comprises first and second insulation carrying mandrels  204   a,    204   b,  which comprises first and second insulation support surfaces  206   a,    206   b  provided by insulation support walls  208   a,    208   b.  First and second insulation carrying mandrels  204   a,    204   b  may further comprise a plurality of air passages  210   a,    210   b  which extend through the by insulation support walls  208   a,    208   b  of the first and second mandrels  204   a,    204   b  from the first and second insulation support surfaces  206   a,    206   b  to an internal air chamber  212  located within the insulation carrier  204 . The internal air chamber  212  may be coupled (in fluid communication) to a vacuum (negative air pressure) source  114  or a compressed gas (positive pressure) source  116  by operation of valve  118 . 
         [0052]    Referring now to  FIG. 4 , in certain embodiments, it may be desirable to preform the sheets of insulating material  40   a,    40   b  to a three-dimensional shape approximating that of the molded plastic article  10  on the insulation carrier  204 . In order to form the sheets of insulating material  40   a,    40   b  to a three-dimensional shape approximating that of the molded plastic article  10 , vacuum may be applied through air passages  210   a,    210   b  while internal air chamber  212  is in fluid communication with vacuum source  114  such that the sheets of insulating material  40   a,    40   b  are vacuum-formed over and onto insulation carrier  204  and conform to the shape of the first and second insulation support surfaces  206   a,    206   b  and support walls  208   a,    208   b  of the first and second carrying mandrels  204   a,    204   b.    
         [0053]    It should be understood that preforming of the sheets of insulating material  40   a,    40   b  to a three-dimensional shape approximating that of the molded plastic article  10  may not be performed on the insulation carrier  204  in all instances. For example, the sheets of insulating material  40   a,    40   b  may be preformed to a three-dimensional shape prior to being loaded on the insulation carrier  204 , in which case the insulation carrier  204  may or may not provide additional forming to the preformed sheets of insulating material  40   a,    40   b.    
         [0054]    Thereafter, as shown in  FIG. 5 , the insulation carrier  204  may be moved on a rail  120  from the insulation loading/forming station to a molding station, and particularly within the confines of a second tool  220 . As shown, second tool  220  may comprise a blow mold  222 , which comprises opposing mold halves  222   a,    222   b.    
         [0055]    As shown, blow mold halves  222   a,    222   b  may each comprise a blow mold surface halves  224   a,    224   b,  respectively, which define an internal molding cavity  228 . As shown, each blow mold half  222   a,    222   b  further comprise a plurality of air passages  232   a,    232   b  which extend through the blow mold halves  222   a,    222   b  from the surface halves  224   a,    224   b  to internal air chambers  234   a,    234   b  located within the blow mold halves  222   a,    222   b.  As shown in  FIG. 6 , internal air chambers  234   a,    234   b  may be coupled (in fluid communication) to a vacuum (negative air pressure) source  130   a,    130   b  or a compressed air (positive air pressure) source  132   a,    132   b  by operation of valve  134   a,    134   b.    
         [0056]    With reference now to  FIGS. 5 and 6 , once the insulation carrier  204  is properly located between blow mold halves  222   a,    222   b,  the blow mold halves  222   a,    222   b  may be closed until the parting surfaces  240   a,    240   b  of the blow mold halves  222   a,    222   b  contact the parting surfaces  214   a,    214   b  on the insulation carrier  204 . 
         [0057]    Once the blow mold halves  222   a,    222   b  are closed as set forth above, vacuum may be drawn through air passages  232   a,    232   b  while internal air chambers  234   a,    234   b  are in fluid communication with vacuum sources  130   a,    130   b.  At the same time, if negative air pressure is still being applied to the insulation carrier  204 , the vacuum being drawn through air passages  210   a,    210   b  may be terminated. 
         [0058]    In such manner, with the change in vacuum from the insulation carrier  204  to the blow mold halves  222   a,    222   b,  the preformed sheets of insulating material  40   a,    40   b  may be transferred from being retained by the first and second insulating carrying mandrels  204   a,    204   b  to being retained by the blow mold halves  222   a,    222   b.  Moreover, to further aid the transfer of the preformed sheets of insulating material  40   a,    40   b  from the insulation carrier  204  to the blow mold  222 , positive air pressure (greater than ambient) may be applied to the insulation carrier  204 . 
         [0059]    Alternatively, rather than terminating the vacuum applied to the insulation carrier  204 , the vacuum applied through the blow mold halves  222   a,    222   b  may be greater than the vacuum applied to the insulation carrier  204 , in which case the vacuum associated with both the insulation carrier  204  and the blow mold halves  222   a,    222   b  may not have to be turned off during the molding cycle. 
         [0060]    Referring now to  FIG. 7  once the preformed sheets of insulating material  40   a,    40   b  have been transferred to the blow mold halves  222   a,    222   b,  the blow mold halves  222   a,    222   b  may be opened, and the insulation carrier  204  removed from the blow mold  222  on rail  120  and returned to the insulation loading/forming station. 
         [0061]    Thereafter, an extruder  160  may be used to provide an extrudate  50  from an extrusion die  166  located above and between the mold halves  222   a,    222   b.  More particularly, as shown in  FIG. 7 , the extrudate  50  may be in the form of a cylindrical parison which is extruded between mold halves  222   a,    222   b.  Vacuum source  130   a,    130   b,  compressed air source  132   a,    132   b  and valves  134   a,    134   b  are not shown in  FIG. 7  for clarity. 
         [0062]    Referring now to  FIG. 8 , once the extrudate  50  has reached the bottom of the mold halves  222   a,    222   b,  the blow mold halves  222   a,    222   b  may be closed such that the mold parting surfaces  240   a,    240   b  seal against the extrudate/parison  50 . At the bottom end of the mold  222 , a blow pin  170  in fluid communication with a pressurized gas source  174  may be inserted into the interior  54  of the extrudate/parison  50  before the mold closes. Once the mold has closed, compressed gas from gas source  174  may enter the interior of the extrudate/parison  50  and inflate the extrudate/parison  50  such that the extrudate/parison  50  takes the shape of the molding cavity  228  and melt bonds/welds to the preformed sheets of insulation material  40   a,    40   b,  by virtue of the extrudate/parison  50  being in a melt state, to form the inner substrate layer  20  of the molded plastic article  10 . After cooling for a suitable time, the blow mold  222  may be opened and the molded plastic article  10  removed from the mold  222 . 
         [0063]    Referring now to  FIG. 9 , after being removed from the mold  222 , the molded plastic article/blow molded airflow conduit  10  may be trimmed, including the forming of an airflow inlet  14  and airflow outlet  18  therein, which extends through the inner substrate layer  20  and an outer (thermal and/or sound) insulation layer  30 . Airflow inlet  14  and airflow outlet  18  may be formed by mechanical cutting, laser, water jet or other suitable trimming device. 
         [0064]    As shown by  FIGS. 1, 2 and 9 , by performing the sheets of insulating material  40   a,    40   b  to a three-dimensional shape approximating that of the molded plastic article  10 , the a molded plastic article  10  may be produced with the insulating layer  30  which substantially covers the entire surface area, i.e. at least 95% of the surface area, of the molded plastic article  10  with insulation material. The insulating layer  30  may be used to cover substantially all of the surface area of the molded plastic article  10  to provide the greatest thermal and/or sound insulation to the molded plastic article  10 . However, it should be understood that while the greatest thermal and/or sound insulation for the molded plastic article  10  may be achieved when the insulating layer  30  substantial covers the entire surface area of the molded plastic article  10 , depending on application, the insulating layer  30  may not have to substantial cover the entire surface area of the molded plastic article  10  to achieve its objectives. Thus, the sheets insulating layer  30  may cover, for example at least 50%, at least 50% 60%, at least 70%, at least 80%, or at least 90% of the surface area of the molded plastic article  10 . For example, it may be plausible in certain embodiments that only half of the molded plastic article  10  is covered with outer insulation layer  30 , in which case only one of the sheets of insulating material  40   a,    40   b  may be required. 
         [0065]    Referring now to  FIG. 10 , in an alternative embodiment, each of the mold halves  222   a,    222   b  of blow mold  222  may include an extendable/retractable parison sealing member  244   a,    244   b,  which co-operate with one another to seal against the extrudate/parison  50  before the blow mold  222  closes. As shown, once the distal end of the extrudate/parison  50  passes the bottom end of mold  222 , the parison sealing members  244   a,    244   b  may be extended to seal against the extrudate/parison  50 , at which time compressed gas from gas source  174  may enter the interior of the extrudate/parison  50  and at least partially inflate the extrudate/parison  50  before the blow mold  222  closes. As the blow mold  222  closes, the parison sealing members  244   a,    244   b  may then retract into receptacles  248   a,    248   b.    
         [0066]    Referring now to  FIG. 11 , there is shown a cross-sectional view of a the preformed sheets of insulation material  40   a,    40   b  on a second embodiment of the insulation carrier  204  within the confines of the opened blow mold halves  222   a,    222   b  of blow mold  222 . In contrast to the first embodiment, first and second insulation carrying mandrels  204   a,    204   b  of insulation carrier  204  are extendable and retractable on pneumatic pistons  216   a,    216   b  mounted between the first and second insulation carrying mandrels  204   a,    204   b  and a center support member  218 . 
         [0067]    With the foregoing arrangement, vacuum may first be applied through air passages  210   a,    210   b  while internal air chambers  212   a,    212   b  are in fluid communication with vacuum source  114  such that the sheets of insulating material  40   a,    40   b  are vacuum-formed over and onto insulation carrier  204  and conform to the shape of the first and second insulation support surfaces  206   a,    206   b.    
         [0068]    Thereafter, once the insulation carrier  204 , including the preformed sheets of insulating material  40   a,    40   b,  is properly located between blow mold halves  222   a,    222   b,  the pneumatic pistons  216   a,    216   b  may be extended to extend the first and second insulation carrying mandrels of the insulation carrier  204  towards blow mold halves  222   a,    222   b  of the blow mold  222  until the parting surfaces  214   a,    214   b  on the insulation carrier  204  make contact with the parting surfaces  240   a,    240   b  of the blow mold halves  222   a,    222   b.    
         [0069]    Once the first and second insulation carrying mandrels  204   a,    204   b  of the insulation carrier  204  have been extended as set forth above, vacuum may be drawn through air passages  232   a,    232   b  of the blow mold halves  222   a,    222   b  of the blow mold  222  while internal air chambers  234   a,    234   b  are in fluid communication with vacuum sources  130   a,    130   b.  At the same time, if vacuum is still being applied to the insulation carrier  204 , the vacuum being drawn through air passages  210   a,    210   b  may be terminated. 
         [0070]    In such manner, with the change in vacuum from the insulation carrier  204  to the blow mold halves  222   a,    222   b,  the preformed sheets of insulating material  40   a,    40   b  may be transferred from being retained by the first and second insulation carrying mandrels  204   a,    204   b  to being retained by the blow mold halves  222   a,    222   b.  Moreover, to further aid the transfer of the preformed sheets of insulating material  40   a,    40   b  from the insulation carrier  204  to the blow mold  222 , positive air pressure (greater than ambient) may be applied to the insulation carrier  204 . 
         [0071]    Alternatively, rather than terminating the vacuum applied to the insulation carrier  204 , the vacuum applied through the blow mold halves  222   a,    222   b  may be greater than the vacuum applied to the insulation carrier  204 , in which case the vacuum associated with both the insulation carrier  204  and the blow mold halves  222   a,    222   b  may not have to be turned off during the molding cycle. 
         [0072]    Thereafter, the pneumatic pistons  216   a,    216   b  may be retracted to retract the first and second insulation carrying mandrels  204   a,    204   b  of the insulation carrier  204  towards center support member  218  thereof, and the insulation carrier  204  removed from the blow mold  222  on rail  120  and returned to the insulation loading/forming station. 
         [0073]    Thus, rather than having the blow mold halves  222   a,    222   b  of the blow mold  222  move towards and away from the first and second insulation carrying mandrels  204   a,    204   b  of the insulation carrier  204  as with the first embodiment, the second embodiment enables the first and second insulation carrying mandrels  204   a,    204   b  of the insulation carrier  204  to move towards and away from the blow mold halves  222   a,    222   b  of the blow mold  222 . Furthermore, the present embodiment also permits both the first and second insulation carrying mandrels  204   a,    204   b  of the insulation carrier  204  and the blow mold halves  222   a,    222   b  of the blow mold  222  to simultaneously move towards each other or away from each other in another variation of the process. 
         [0074]    With regards to materials, the sheets of insulation material  40   a,    40   b  forming the exposed outer (thermal and/or sound) insulation layer  30  of the molded plastic article  10  may comprise a polymer composition formed with a cellular (foam) structure, particularly by providing voids formed in the polymer (matrix) composition. The cellular structure may be formed by a blowing agent (e.g. chemical of physical) released in the polymer composition. 
         [0075]    For noise attenuation, the polymer foam for insulation material  40   a,    40   b  may have a closed cell content of at least 50%, and more particularly at least 65%, such as in a range of 10% to 50% or 10% to 65%. Even more particularly, the foam may have a closed cell content of up to 70%. In such a manner, air cannot flow through the material, thus creating a sound barrier. Furthermore, given that air cannot flow through the material, the material also provides a thermal insulator. 
         [0076]    The polymer foam for the sheets of insulation material  40   a,    40   b  may have a thickness in a range of 2 mm to 10 mm, and more particularly in a range of 3 to 6 mm. A thicker sheet may offer greater noise attenuation, but such must be balanced against greater weight and cost. 
         [0077]    The polymer foam for the sheets of insulation material  40   a,    40   b  may have a density in a range of 0.5 lb/ft 3  to 5 lbs/ft 3 , and more particularly in a range of 1 lb/ft 3  to 3 lbs/ft 3 . The density of the foam should be low to reduce weight and increase sound absorption. Furthermore, the low density of the foam enables suitable heat transfer through the foam material from the extrudate  50  to the blow mold halves  222   a,    222   b  to cool the extrudate  50 /inner substrate layer  20  such that cycle times may not be increased. 
         [0078]    An exemplary polymer foam for insulation material  40   a,    40   b  may particularly comprise a polyurethane foam, particularly a thermoset polyurethane foam. As exemplary urethane foam is Resilifoam® urethane LC-2 (Lok Cell) from Plastomer Corporation. 
         [0079]    In addition to the insulation material  40   a,    40   b  providing increased thermal efficiency and/or noise attenuation, the insulation material  40   a,    40   b,  also provides a trap for condensate. As HVAC systems, and particularly airflow conduits, become more efficient, condensate may form on the outer surface of an airflow conduit if the air outside the airflow conduit has a high moisture (humidity/water) content and the temperature of the air in contact with the surface of the duct drops below its dew point. Condensate which forms on the surface of the airflow conduit may then flow on the airflow conduit into other parts of the motor vehicle, which may potentially result in numerous problems, such as contributing to the rusting of metal components under the instrument panel. 
         [0080]    However, formation of the condensate, as well subsequent flow of the condensate, should the condensate form, may both be inhibited by the insulation material  40   a,    40   b.  As such, the insulation material  40   a,    40   a,  may be a polymer foam which does not have an outer skin, and which has an open cell content of at least 10%. More particularly, the polymer foam may have an open cell content in a range of 10% to 50%, and even more particularly in a range of 10% to 25%. 
         [0081]    The material for the extrudate  50 /inner substrate layer  20  may be a thermoplastic polymer composition having a thickness in a range of 0.5 mm to 2.5 mm, and more particularly in a range of 1 mm to 2 mm. The thermoplastic polymer may include a polyolefin (i.e. a class of polymers produced from a simple olefin (also called an alkene with the general formula CnH2n) as a monomer), which may include polypropylene (PP) and polyethylene (PE), such as high density polyethylene (HDPE). Other thermoplastics may include polyester, such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT). 
         [0082]    In order to provide suitable rigidity, the extrudate  50 /inner substrate layer  20  may be formed of a polymer composition having a flexural modulus as measured in accordance with ASTM D-790-10 of at least 125,000 psi. at room temperature (23° C.) in order for substrate to provide sufficient rigidity to support article  10 . More particularly, the substrate  20  may have a flexural modulus as measured in accordance with ASTM D-790-10 in a range of 125,000-400,000 psi. at 23° C. 
         [0083]    In addition to providing sufficient rigidity for substrate  20  of article  10 , the composition for substrate  20  should also provide suitable heat resistance. As such, the substrate  20  may be formed of a polymer composition having a heat distortion temperature as measured in accordance with ASTM D-648-07 of at least 82° C. at 264 psi. More particularly, the substrate  20  may have a heat distortion temperature as measured in accordance with ASTM D-648-07 in a range of 82-110° C. at 264 psi. 
         [0084]    While a preferred embodiment of the present invention(s) has been described, it should be understood that various changes, adaptations and modifications can be made therein without departing from the spirit of the invention(s) and the scope of the appended claims. The scope of the invention(s) should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents. Furthermore, it should be understood that the appended claims do not necessarily comprise the broadest scope of the invention(s) which the applicant is entitled to claim, or the only manner(s) in which the invention(s) may be claimed, or that all recited features are necessary.