Abstract:
A manifold for a liquid material dispenser has a unitary manifold body with process air and liquid material passages formed therethrough. Heaters for heating the process air and liquid material are both coupled directly to the manifold body and cooperate to simultaneously heat both the air and liquid material. The air and liquid material heaters may be arranged in either a generally vertical orientation, or a horizontal orientation with respect to the manifold body. In one embodiment, the process air heater includes a cylindrical member which is substantially exposed to the process air to optimize heat transfer from the cylindrical member to the process air.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to liquid material dispensing systems, and more particularly to applicators for dispensing controlled patterns of thermoplastic material to a substrate. 
   BACKGROUND OF THE INVENTION 
   Dispensing systems for supplying liquid material and filaments in other forms are conventionally used to apply thermoplastic materials, such as hot melt adhesives, to various substrates during the manufacture of diapers, sanitary napkins, surgical drapes, and other substrates. Typically, liquid material and pressurized air are supplied to the dispenser where they are heated and distributed to one or more dispensing modules for application to the substrate. The heated liquid material is discharged from the dispensing module while pressurized air is directed toward the dispensed liquid to attenuate or draw down the dispensed liquid material and to control the pattern of the liquid material as it is applied to the substrate. 
   Conventionally, liquid material dispensing systems have utilized separate manifolds for heating and supplying the pressurized air and liquid material to the dispensing modules. Accordingly, the separate air and liquid material manifolds use separate heaters specifically dedicated to heat the respective air and liquid material. Generally, the requirements for heating the liquid and air are different, therefore, different types of heating elements are typically used for each heater and the heating elements are separately controlled. This in turn contributes to increased manufacturing costs and the need to stock multiple service parts. Having separate air and liquid material manifolds also inhibits making the dispensers compact in size. Because the air and liquid material heaters are separately controlled, heat generated from one heater can interfere with the temperature control of the other material. For example, the heater for heating the air may be turned off by a controller in an effort to reduce the temperature of the pressurized air, but heat generated by the liquid material heater may continue to heat the air, thereby effectively contravening efforts to control the air temperature with the air heater. Finally, a dispenser having separate manifolds increases manufacturing time due to the need to couple together the individual manifolds to produce the adhesive dispenser. 
   Adhesive dispensing systems generally have manifolds configured to accommodate a fixed number of adhesive dispensing modules. Often, however, it is desirable to have an adhesive dispenser of a modular configuration which permits manifolds of the dispenser to be joined together or separated to permit flexibility in increasing or decreasing the number of modules which can be used in a given application. Such modular adhesive dispensers present unique challenges such as maintaining uniform heating across all modules so that liquid material is uniformly dispensed to the substrate, particularly from dispensing modules located at the ends of each manifold where less heat from the manifold heaters is transferred to the liquid material due to heat losses through the ends of the manifold. 
   A need therefore exists for an improved liquid material dispensing system which addresses various drawbacks of prior dispensing systems, such as those described above. 
   SUMMARY OF THE INVENTION 
   The present invention provides an integrated manifold for a dispensing system, as well as a dispenser incorporating the manifold, preferably used to dispense hot melt adhesives in an air assisted manner. The dispenser dispenses liquid material and process air from at least one dispensing module coupled to the manifold. The manifold of this invention integrates a process air distribution portion and a liquid distribution portion into a common, integral manifold body or block, which is preferably an aluminum extrusion. Unlike conventional hot melt adhesive systems, the power requirements for heating the process air are shared between a heater specifically designed to heat the incoming process air and at least one additional heater which heats both the liquid material and the process air. 
   More specifically, an integrally formed manifold body is configured to receive one or more of the dispensing modules thereon and includes an internal air heater passage. Liquid and process air supply passages are provided in the manifold body. A plurality of liquid passages in the manifold body communicate with the liquid supply passage to provide the liquid material to the module(s). A plurality of process air passages in the manifold body communicate with the process air supply passage to provide process air to the module(s). A first heating member is positioned within the internal air heater passage and a gap is formed between the first heating member and the manifold body. The gap forms a portion of the process air supply passage. A second heating member is operatively coupled to the manifold body proximate the liquid passages and supplies heat to the liquid material in the liquid passages and also supplies heat the process air in the gap and the process air passages. 
   A first temperature sensor is positioned in the manifold body at a location such that the first temperature sensor senses a temperature approximating the temperature of the process air provided to the modules from the process air passages, while minimizing the thermal effects of the second heating member on the first temperature sensor. A second temperature sensor is positioned in the manifold body at a location such that the second temperature sensor senses a temperature approximating the temperature of the liquid material provided to the modules from the liquid passages, while minimizing the thermal effects of the first heating member on the second temperature sensor. Advantageously, the first and second heating members are comprised of identical heating elements. First and second embodiments are disclosed in which the first and second heating members respectively extend substantially parallel to and transverse to the longitudinal extent of the manifold body. The manifold body further includes first and second ends each having fastening elements for coupling the manifold body to another manifold body, in side-by-side relation, to expand the number of dispensing modules of the dispensing system. This feature is especially adapted for the embodiment having transversely extending heating members. 
   The first heating member or process air heating member preferably further comprises an elongate cylindrical member. The cylindrical member may be a cartridge style heating element of an appropriate diameter, but in the preferred embodiment, the elongate cylindrical member includes a lengthwise extending central passage and an elongate, electrically operated variable heating element is positioned within the central passage. A groove is located on an outer surface of the cylindrical member and extends at least substantially around the circumference of the elongate cylindrical member. The groove is configured to receive process air to be heated by the elongate cylindrical member and communicates with the gap. The process air is heated by the manifold block on one side of the gap and by the first heating member on the opposite side of the gap. Since the manifold block is directly heated by the second heating member, the load for heating the process air is shared between the first and second heating members. Also, since the first heating member, e.g., the elongate cylindrical member, is spaced from the manifold block by the aforementioned gap, the heat supplied to the process air is effectively carried away by the process air moving through the gap. This minimizes the effect of variations in the heat supplied to the process air by the first heating member on the liquid sections of the manifold body. Thus, the set point temperature of the liquid may be more precisely maintained as the process air temperature is varied by controlling the power to the first heating member. 
   The features and various advantages of the inventive aspects will become more readily apparent to those of ordinary skill in the art upon further review of the detailed description of the preferred embodiments taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention. 
       FIG. 1  is a perspective view of an exemplary liquid material dispenser of the present invention; 
       FIG. 2  is a cross-sectional view of the liquid material dispenser of  FIG. 1 , taken along lines  2 — 2 ; 
       FIG. 2A  is an exploded detail view of the encircled area of  FIG. 1 ; 
       FIG. 3  is a cross-sectional view of the liquid material dispenser of  FIG. 1 , taken along lines  3 — 3 ; 
       FIG. 3A  is a cross-sectional view of the liquid material dispenser of  FIG. 1 , taken along lines  3 A— 3 A of  FIG. 3 ; 
       FIG. 4  is a perspective view of another exemplary liquid material dispenser according to the present invention; 
       FIG. 5  is an exploded perspective view of the liquid material dispenser of  FIG. 4 , viewed from the rear; 
       FIG. 6  is a cross-sectional view of the liquid dispenser of  FIG. 4 , taken along lines  6 — 6 ; 
       FIG. 7  is a cross-sectional view of the liquid dispenser of  FIG. 4 , taken along lines  7 — 7  of  FIG. 6 ; 
       FIG. 8  is a cross-sectional view of the liquid dispenser of  FIG. 4 , taken along lines  8 — 8  of  FIG. 6 ; and 
       FIG. 9  is a fragmented combination of the cross sections shown in  FIGS. 7 and 8  to show both the liquid and air portions of the manifold. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1 , there is shown an exemplary liquid material dispenser  10  according to the present invention. The liquid material dispenser  10  includes a unitary manifold body  12  which has been formed and machined to accommodate the various components of the liquid dispensing system, as will be described more fully below. The manifold body  12  has oppositely disposed front and rear surfaces  14 ,  16 , oppositely disposed upper and lower surfaces  18 ,  20 , and oppositely disposed longitudinal ends  22 ,  24 . The manifold body  12  is supported by support members  25   a ,  25   b  attached to the upper surface  18  of the manifold body  12 . 
   Several liquid dispensing modules  30  are secured to the front surface  14  of the manifold body  12  by fasteners  32 . The dispensing modules  30  may be on/off-type modules with internal valve structure for selectively dispensing liquid material in the form of one or more filaments. An exemplary module of this type is disclosed in U.S. Pat. No. 6,089,413, commonly assigned to the assignee of the present invention and incorporated herein by reference in its entirety. 
   Liquid material, such as hot melt adhesive, and pressurized process air is supplied to the individual modules  30  through the manifold body  12  to thereby dispense beads or filaments of the liquid material to a substrate. The dispenser  10  further includes first, process air heating members  34   a ,  34   b  and second, liquid material heating members  36   a ,  36   b  for heating the air and liquid material, as will be described more fully below. Filters  38   a ,  38   b  are installed in the manifold body  12  to filter out contaminants from the liquid material supplied to the modules  30 , and temperature sensors  40   a ,  40   b  and  42   a ,  42   b  are provided to measure the temperature of the liquid material and process air. Signals from the temperature sensors  40   a ,  40   b ,  42   a ,  42   b  are supplied to a controller (not shown) which controls the air and liquid heaters  34   a ,  34   b  and  36   a ,  36   b  to regulate the temperature of the air and adhesive dispensed from the modules  30 . Each of the components described above is mounted to the unitary manifold body  12  as shown and described herein. In the description that follows, the dispenser of  FIG. 1  includes two sets of process air passages through the manifold body, and two process air heaters. However, because the passages and heaters are identical, only one will be described, with the understanding that the description is applicable to the other air passages and other process air heater. 
   Referring now to  FIG. 2 , there is shown a cross-sectional view of the liquid material dispenser  10  of  FIG. 1 , depicting the path of process air through the manifold body  12  to the dispensing modules  30 . Process air is supplied to the dispenser  10  from a source of pressurized air (not shown) and is routed to the individual modules  30  through a series of interconnected passages. Process air enters the dispenser  10  through an air inlet port  50  formed in the rear surface  16  of the manifold body  12 . A fitting  52  coupled to the air inlet port  50  facilitates the attachment of an air line connected to the pressurized air source. 
   A first, vertical bore  54  is formed through the top surface  18  of the manifold body  12  and extends downwardly through the manifold body  12  to intersect an air supply passage  56 . The first bore  54  also communicates with the air inlet port  50  and is sized to receive the first heating member  34   a  for heating the incoming process air. In the embodiment shown, the first heating member  34   a  includes an elongate cylindrical member  60  that is received within the first bore  54  and spaced from the sidewalls of the first bore  54  to provide a clearance gap  62  along the length of the cylindrical member  60 . In one embodiment, the clearance gap  62  is approximately 0.015 inch to 0.025 inch and process air is provided through the manifold body at a rate of approximately 0.5 to 2 SCFM (standard cubic-feet-per-minute) per module. The cylindrical member  60  is shown more clearly in  FIG. 2A , which depicts another first heating member  34   b  removed from first bore  54 . 
   Referring to  FIGS. 2 and 2A , a first circumferential groove  64  is formed in the cylindrical member  60 , adjacent the air inlet port  50 , whereby incoming process air may be evenly distributed around the cylindrical member  60  prior to being forced through the gap  62  toward the air supply passage  56 . An O-ring  66  provided in a second circumferential groove  68  formed on a first end  70  of the cylindrical member  60 , opposite the air supply passage  56 , seals the first bore  54  and helps to center the cylindrical member  60  within the first bore  54 . In an exemplary embodiment, the O-ring  66  is formed from a high-temperature resistant material such as Viton®. 
   The cylindrical member  60  is formed from a conductive material, such as metal, and has a central passage  72  extending along a longitudinal axis from the first end  70  toward the air supply passage  56 . A first heating element  74  is disposed within the central passage  72  and is connected by an electrical lead  76 , protected by conduit  77 , to an appropriate power source (not shown). The heating element  74  and cylindrical member  60  are secured to the upper surface  18  of the manifold body by a clamp  75  and threaded fastener  79 . In the embodiment shown, the heating element  74  is a cartridge heater, but it will be recognized that the heating element  74  may alternatively be other types of heating elements, as known in the art. Accordingly, when current is supplied to the heating element  74  through the electrical lead  76 , the heating element  74  heats the cylindrical member  60  which, in turn, heats process air flowing through the inlet port  50  and along the gap  62  toward the air supply passage  56 . The configuration of the first heating member  34   a  provides an efficient way to transfer heat to the process air. Specifically, the cylindrical member  60  is substantially enveloped in the process air such that heat from the cylindrical member must pass through the process air, except at the first end  70  where the cylindrical member  60  is sealed to the manifold body  12 . 
   As shown in  FIG. 2 , the air supply passage  56  provides fluid communication between the first bore  54  and an air distribution passage  80  extending longitudinally through the unitary manifold body  12 , along a direction parallel to the bank of liquid dispensing modules  30 . In the exemplary embodiment shown, the air supply passage  56  is formed as a blind hole machined through the rear surface  16  of the manifold body  12 . A plug  82  is provided at the rear surface  16  to seal the air supply passage  56  and is removable to facilitate cleaning and/or servicing of the air supply passage  56 . Again, while only one process air heater  34   a  and one set of air passages  50 ,  54 ,  56  has been described and shown, the embodiment of  FIG. 1  has two sets of air passages and two process air heaters, the other air passage and the second air heater  34   b  being identical to those described above. 
   With continued reference to  FIG. 2 , a plurality of air outlet passages  84  are formed in the front face  14  of the manifold body  12  and intersect the air distribution passage  80  whereby process air is provided from the air distribution passage  80  and through the outlet passages  84  to each module  30  secured to the front face  14  of the manifold body  12 . Thereafter, process air travels through various air passages formed in the modules  30  and is dispensed from air discharge outlets  86  on dispensing dies  88  coupled to the respective modules  30 , as known in the art. 
   As shown in  FIGS. 1 and 2 , a first temperature sensor  40   a  is installed in the manifold body  12 , adjacent the first heating member  34   a , through a bore  89  formed through the top surface  18  and extending parallel to the first bore  54 . Advantageously, the location of the first temperature sensor  40   a  is selected such that the sensed temperature corresponds closely to the temperature of the process air discharged from the modules  30 . The location of the first temperature sensor  40   a  may be determined, for example, by finite element analysis. 
   Referring now to  FIGS. 3 and 3A , there are shown cross-sections through different portions of the unitary manifold body  12 , depicting the path of liquid material through the manifold  12  to the dispensing modules  30 . While the embodiment shown in  FIG. 1  includes two liquid material filters and heaters, with associated liquid material passages, only one set of passages with the corresponding filter and heater will be described, it being understood that the description is equally applicable to the other liquid passages, filter and heater. 
   As shown in  FIGS. 3 and 3A , liquid material is supplied to the manifold body  12  through a fitting  90  coupled to a liquid material inlet port  92  at the rear surface  16  of the manifold body  12 . The inlet port  92  leads to a vertically-oriented filter cavity  94  formed into the manifold body  12  from the upper surface  18  and sized to receive a filter  38   b  for removing contaminants from the incoming liquid material. An inlet liquid supply passage  96  formed longitudinally through the manifold body  12  provides fluid communication between the two liquid material filters  38   a ,  38   b  so that the liquid material is distributed between the two filters and associated passages. The filter  38   b  is inserted into the filter cavity  94  from the upper surface  18  of the manifold body  12  and has an O-ring  98  to seal the upper end of the cavity  94 . The filter  38   b  depicted in this embodiment is shown and described in co-pending U.S. patent application Ser. No. 10/831,016, entitled “A FILTER ASSEMBLY FOR A LIQUID DISPENSING APPARATUS” filed on Apr. 22, 2004 and assigned to the assignee of the present invention. 
   Liquid material enters the filter  38   b  through circumferentially spaced inlets  100  and circulates through the filter  38   b  whereafter filtered liquid material exits toward the bottom  102  of the filter cavity  94 . Thereafter, the liquid material enters an adhesive distribution passage  104  communicating with the filter cavity  94  and extending longitudinally along the manifold body  12 , adjacent the bank of liquid dispensing modules  30  and parallel to the process air distribution passage  80  and the inlet supply passage  96 . As shown in  FIG. 3 , a plurality of liquid outlet passages  106  are formed into the manifold body  12 , from the front surface  14 , and intersect the liquid distribution passage  104  whereby liquid material flows from the liquid distribution passage  104 , through the liquid outlet passages  106  to each of the dispensing modules  30  mounted on the front surface  14  of the manifold body  12 . The liquid material travels through various liquid passages formed in the modules  30  and is discharged from one or more liquid discharge outlets  108  provided on dispensing dies  88  coupled to each module  30 , as known in the art. 
   With continued reference to  FIGS. 3 and 3A , the liquid material flowing through the liquid passages  92 ,  94 ,  104 ,  106  of the manifold body  12  is heated by a second heating member  36   b  disposed in a second, vertical bore  112  formed into the manifold body  12  from the upper surface  18  of the manifold body  12 . In the embodiment shown, the second heating member  36   b  is located adjacent the filter cavity  94  whereby heat from heating member  36   b  is conducted through the manifold body  12  to heat liquid material flowing through the filter cavity  94  and other liquid passages  92 ,  104 ,  106 . In this embodiment, the second heating member  36   b  is a cartridge heater which is secured within the vertical bore  112  by a clamp  114  fastened to the upper surface  18  of the manifold body  12  by a threaded fastener  115 . Electrical leads  116  from the heater cartridge are routed through a protective conduit  118  connected to an appropriate current source, as known in the art. 
   As depicted in  FIGS. 1 and 3A , a second temperature sensor  42   b  is mounted to the manifold body  12  at a position where the sensed temperature closely corresponds to the temperature of the liquid material discharged from the dispensing modules  30 . In another embodiment, the locations of the first and second temperature sensors  40   a ,  42   a  are selected to minimize the effects of the heater associated with the other temperature sensor, to approximate a thermally decoupled system. This permits the controller to more accurately control each heater to heat the liquid material and the process air to desired operating ranges. 
   Because both the first and second heating members  34   a ,  34   b  and  36   a ,  36   b  are mounted directly within the manifold body  12 , and because the liquid and adhesive passages are formed through the unitary manifold body  12 , it will be recognized that heat emanating from the second heating members  36   a ,  36   b  is conducted through the manifold body  12  to heat not only the liquid material, but also the process air flowing through the process air passages. Specifically, heat conducted through the manifold body  12  from the second heating members  36   a ,  36   b  provides heat to portions of the manifold body  12  surrounding the first bore  54  to cooperate with the first heating members  34   a ,  34   b  to heat process air flowing through the clearance gap  62  and other air passages  50 ,  54 ,  56 . However, heat from the first heating members  34   a ,  34   b  is substantially isolated from the rest of the manifold body  12  by the process air flowing through the clearance gap  62  and therefore does not significantly affect the temperature of the liquid material flowing through the manifold body  12 . This arrangement, in conjunction with the configuration of the first heating members  34   a ,  34   b  discussed above, provides a robust and efficient mechanism for heating the process air and minimizes heat loss between the first heating members  34   a ,  34   b  and the process air. Because heat loss from the first heating members  34   a ,  34   b  is minimized, the heating elements  74  of the first heating members  34   a ,  34   b  do not have to be overdesigned to obtain a desired temperature rise in the process air. 
   Referring again to  FIG. 1 , the adhesive dispenser  10  of the present invention includes insulating endplates  120  mounted on the respective longitudinal ends  22 ,  24  of the manifold body  12 . Advantageously, the end plates  120  help to minimize heat loss through the ends  22 ,  24  of the manifold body, thereby improving the thermal efficiency of the dispenser  10 . 
   While the liquid dispenser  10  has been shown and described herein as having two sets of first and second heating members, filters, and associated air and liquid passages, it will be recognized that a liquid dispenser could alternatively be provided with only a single set of heaters, filters and associated air and liquid passages, or alternatively more than two sets of heaters, filters, and passages, as may be required for a particular application. Moreover, the vertical arrangement of heaters and filters facilitates adding additional manifold segments to accommodate a greater number of liquid dispensing modules  30 , or alternatively providing additional heaters, filters, and associated flow passages into a common manifold. 
   Referring now to  FIGS. 4 and 5 , there is shown another embodiment of an adhesive dispenser  150  according to the present invention. The adhesive dispenser  150  shown in this embodiment is similar to the dispenser  10  depicted in  FIGS. 1–3 , with the exception that instead of vertically-oriented heating members, the first and second heating members  152 ,  154  are disposed in respective first and second bores  156 ,  158  of a unitary manifold body  160  having longitudinal axes extending in directions substantially parallel to the longitudinal direction of the manifold body  160 . The manifold body  160  has upper and lower surfaces  162 ,  164 , front and rear surfaces  166 ,  168 , and oppositely disposed longitudinal lends  170 ,  172 . A bank of liquid dispensing modules  30  are operatively coupled to the front surface  166  of the manifold body  160 , in a manner similar to that previously described with respect to the dispenser  10  of  FIGS. 1–3 . In this embodiment, the various fittings for coupling the manifold body  160  to liquid material and process air supply lines, as well as access openings or bores for the heating members  152 ,  154  and liquid filters  174   a ,  174   b  are provided on the rear surface  168  and longitudinal ends  170 ,  172  instead of the top surface  162  of the manifold body  160 , as will be described more fully below. 
   Referring now to  FIGS. 6 and 7 , the flow path of the process air through the manifold body  160  of this embodiment will now be described. The manifold body  160  has provisions for two process air inlet ports  180   a ,  180   b , both located on the rear surface  168  of the manifold body  160 . Appropriate fittings  182  are installed at the first and second air inlet ports  180   a ,  180   b  to couple the air inlet ports  180   a ,  180   b  to a source of pressurized air (not shown). The air inlet ports  180   a ,  180   b  are in fluid communication with a first bore  184  formed through the manifold body  160  along a direction parallel to the longitudinal axis of the manifold body  160 . A pair of first air heating members  152   a ,  152   b  are disposed in the first bore  184 , from opposite longitudinal ends  170 ,  172  of the manifold body  160 . First bore  184  is sealed at its longitudinal ends by O-rings  185  provided on the first heating members  152   a ,  152   b  in a manner similar to that described above for the embodiment of  FIGS. 1–3 . 
   The first heating members  152   a ,  152   b  comprise elongate cylindrical members  186  having central passages  188  for receiving heating elements  190 , as described above. In the embodiment shown, the heating elements  190  are cartridge heaters with electrical wiring for coupling the cartridge heaters to appropriate power sources. The cylindrical members are spaced from the bore  184  to provide annular gaps  192   a ,  192   b  which extend along the lengths of the cylindrical members  186 . The air inlet ports  180   a ,  180   b  are in fluid communication with the first bore  184  whereby air from the source is directed through the inlet ports  180   a ,  180   b  to the first bore  184  and along the gaps  192   a ,  192   b  between the cylindrical members  186  and the first bore  184 . As the air travels through the gaps  192   a ,  192   b , it is heated by the heating members  152   a ,  152   b , as discussed above with respect to  FIGS. 1–3 . 
   With continued reference to  FIGS. 6 and 7 , an air distribution passage  200  extends longitudinally along the manifold body  160 , adjacent the bank of dispensing modules  30 , similar to the air distribution passage  80  of  FIGS. 1–3 . The air distribution passage  200  is in fluid communication with the first bore  184  through three air supply passages  202   a ,  202   b ,  202   c  extending therebetween. Several air outlet passages  204  are formed through the front surface  166  of the manifold body  160  and are in fluid communication with the air distribution passage  200  whereby air entering the manifold  160  through the inlet ports  180   a ,  180   b  is directed through the first bore  184 , through the air supply passages  202   a ,  202   b ,  202   c , through the air distribution passage  200  and air outlet passages  204 , to respective dispensing modules  30 , as previously described. 
   First temperature sensors  203   a ,  203   b  are coupled to the manifold body  160  through longitudinal cavities formed through the longitudinal ends  170 ,  172  thereof, adjacent the first bore  156 , and extending toward the center of the manifold body  160 . In this embodiment, the temperature sensors are located at positions to sense temperatures that closely correspond to the temperature of the process air moving through the air passages and discharged from the dispensing modules  30 . 
   Referring now to  FIGS. 6 and 8 , the flow of the liquid material through the dispenser  150  will now be described. Because the air and liquid passages are formed through different portions of the unitary manifold body  160 , the locational relationship between the air and liquid passages in the manifold body  160  can be appreciated by reference to these figures and with further reference to  FIG. 9 , which depicts a fragmented cross section showing both of these passages. 
   As shown most clearly in  FIG. 8 , the manifold body  160  of the dispenser  150  includes four ports for supplying liquid material to the manifold body  160 , two ports  220   a ,  220   b  provided on the rear surface  168  of the manifold body  160  and additional ports  222   a ,  222   b  provided on each of the longitudinal ends  170 ,  172 . In the embodiment shown, a liquid inlet fitting  224   b  is coupled to a port  222   b  on the second end  172  of the manifold body  160  and a second inlet fitting  224   a  is coupled to an inlet port  220   a  on the rear surface  168  of the manifold body  160 . The remaining inlet ports  220   b ,  222   a  are sealed with threaded plugs  226 , but it will be recognized that fittings may alternatively be secured to these other ports, as may be required for a particular application. 
   The multiple liquid inlet ports  220   a ,  220   b  and  222   a ,  222   b  (collectively referred to herein as  220 ,  222 ) on the manifold body  160  facilitate convenient routing of liquid supply hoses (not shown) to the dispenser  150 . The liquid inlet ports  220 ,  222  are in fluid communication with first and second filter cavities  228   a ,  228   b  by a liquid material inlet supply passage  230  extending longitudinally through the manifold body  160 , whereby liquid material supplied to the manifold body  160  from appropriate liquid sources (not shown) is routed through the filters  174   a ,  174   b  and exit toward the bottoms of the filter cavities  228   a ,  228   b , as previously described with respect to  FIGS. 1–3 . 
   A liquid distribution passage  232  extends longitudinally along the manifold body  160 , similar to the liquid distribution passage  104  of  FIGS. 1–3 , and is in fluid communication with the bottoms of the filter cavities  228   a ,  228   b . Liquid outlet passages  234  are formed through the front surface  166  of the manifold body  160  and are in fluid communication with the liquid distribution passage  232  whereby liquid material supplied through the inlet ports  220 ,  222  goes through the liquid filters  174   a ,  174   b  and filter cavities  228   a ,  228   b , through the liquid distribution passage  232 , and through the liquid outlet passages  234  to the individual modules  30  for dispensing from the modules  30 , as previously described. 
   As depicted in  FIGS. 6 and 8 , second heating members  154   a ,  154   b  are coupled to the manifold body  160  through the respective first and second longitudinal ends  170 ,  172  and extend longitudinally along the manifold body  160  toward the center of the dispenser  150 . In the embodiment shown, the second heating members  154   a ,  154   b  are cartridge heaters that generate heat when coupled to an appropriate power source, as discussed above. The heat is conducted through the manifold body  160  to the liquid passages  228 ,  230 ,  232 ,  234  to thereby heat the liquid material flowing through the liquid passages. Second temperature sensors  240   a ,  240   b  are also coupled to the manifold body  160  and extend longitudinally along the manifold body  160  from respective longitudinal ends  170 ,  172 , adjacent the liquid distribution passage  232 , to measure the temperature of the manifold body  160  at those locations. 
   Advantageously, the locations of the second temperature sensors  240   a ,  240   b  are selected so that the sensed temperatures are very close to that of the liquid material flowing through the liquid distribution passage  232  and provided to the modules  30 . In another embodiment, the locations of the first and second temperature sensors  203   a ,  203   b  and  240   a ,  240   b  are selected to minimize the effects of the heater associated with the other temperature sensor, to approximate a thermally decoupled system. This permits the controller to more accurately control the heating members to heat the liquid material and the process air to desired temperature ranges. Moreover, the second heating members  154   a ,  154   b  cooperate with the first heating members  152   a ,  152   b  to heat the process air flowing through clearance gaps  192   a ,  192   b  and other air passages  184 ,  200 ,  202   a – 202   c , but the first heating members  152   a ,  152   b  do not affect the temperature of the liquid material, as discussed above. 
   The manifold bodies of the embodiments described herein lend themselves to fabrication by extrusion methods. Specifically, the uniform profile of the upper and lower surfaces and the front and rear surfaces of the manifold bodies facilitate forming the manifold bodies by extrusion in the longitudinal direction. After extrusion, various other features, such as screw threads and the various bores and cavities which do not extend in the longitudinal direction, may be machined into the manifold body. Furthermore, it will be appreciated that cavities and bores which extend in the longitudinal direction may be formed in the manifold body during extrusion. For example, the liquid inlet supply passage  96  and the liquid distribution passage  104  of the embodiment of  FIGS. 1–3A  can be extruded into the manifold body  12 . In the embodiment of  FIGS. 4–10 , the first bore  184 , the air distribution passage  200 , the liquid material inlet supply passage  230  and the liquid distribution passage  232  can be extruded into the manifold body  160 . Even when tight tolerances between components are required, these bores and passages can be extruded to nominal dimensions and subsequently machined to the desired dimensions, thereby reducing the overall manufacturing time. 
   While the present invention has been illustrated by the description of one or more embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of Applicant&#39;s general inventive concept.