Abstract:
An apparatus for dispensing a liquid onto a substrate including a horizontally-oriented manifold body having spaced apart front and rear surfaces and a lower surface extending between the front and rear surfaces. The lower surface is adapted to overlie at least a portion of the substrate. At least one dispensing module is mounted on the front surface of the manifold body and includes a discharge end for dispensing liquid onto the substrate. The discharge end is positioned proximate the lower edge of the front surface and the forward edge of the lower surface. The lower surface of the manifold body is angled in an upward direction generally from the front edge to the rear edge to progressively increase the distance between the lower surface and the substrate from front to rear when the front surface is vertically oriented and the substrate is horizontally oriented beneath the manifold body. The angled lower surface also facilitates substrates approaching the apparatus at a similar angle.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention generally relates to liquid material dispensing systems, and more specifically to applicators for dispensing a liquid material onto a substrate.  
       BACKGROUND OF THE INVENTION  
       [0002]     Various liquid dispensing systems have been developed for the precise application of a heated liquid onto a substrate. Dispensing systems for supplying liquid material in the form of filaments or other patterns are known in the art. These dispensing systems are conventionally used to apply thermoplastic materials, such as a hot melt adhesive, to various substrate materials during the manufacturing of diapers, sanitary napkins, surgical drapes, and other products. Typically, liquid material and pressurized process air are supplied to the dispensers 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 heated pressurized process 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.  
         [0003]     Conventional liquid dispensing systems, shown schematically in  FIG. 4 , typically utilize a manifold for heating and distributing the pressurized air and liquid material to the dispensing modules. The manifold generally has a block configuration having a pair of opposed front and rear surfaces, a pair of opposed end surfaces, and opposed upper and lower surfaces. The manifold is configured to accommodate a number of dispensing modules that releasably couple to the manifold typically along the front surface. The dispensing module includes a liquid inlet and a process air inlet that communicate with a liquid outlet and process air outlet in the manifold. The dispensing module further includes a pneumatically or electrically actuated valve assembly for metering a precise quantity of the liquid and discharging the metered amount through a small-diameter dispensing orifice and onto a moving substrate positioned below the orifice. The dispensing end is generally adjacent the lower surface of the manifold. To increase liquid deposition control and accuracy, it is desirable to minimize the distance between the substrate and the dispensing end of the modules. As a result, the distance between the manifold and the substrate passing beneath the manifold is generally small. The distance between the lower surface of the manifold and substrate in conventional liquid dispensing systems, however, have some drawbacks.  
         [0004]     One drawback is that the heaters in the manifold that heat the liquid and process air make the manifold, including the lower surface, very hot. This in turn heats the substrate as it passes underneath the manifold. The heating of the substrate may affect the thermal and structural properties of the substrate material, such as, for example, by weakening it. Moreover, heating the substrate may increase the curing time of the deposited liquid thereby affecting subsequent manufacturing steps, or may affect the spreading of the deposition pattern on the substrate, thereby depositing liquid where none is desired or possibly permitted, depending on the particular application.  
         [0005]     Another drawback is that in some applications, such as when applying elastic strands onto a substrate, the angle at which the strands are fed toward the dispensing modules affects the coating of the strands as they pass by the dispensing orifice. In conventional dispensing systems, the manifold limits the angle at which the strands approach the dispensing orifice thus affecting coating efficiency of the strands. Yet another drawback is that servicing the substrate and the dispensing modules can be difficult in current dispensing systems. For instance, it can often be difficult to align or adjust the substrate, especially on that portion of the substrate directly beneath the manifold without contacting the heated manifold. Additionally, when servicing the dispensing modules a drip pan is typically used to drain the module so as to prevent any liquid from dripping onto the substrate. This may require that the dispensing modules be raised away from the substrate thereby disturbing the desired and established deposition height and deposition pattern.  
         [0006]     A need therefore exists for an improved liquid material dispensing system which overcomes various drawbacks of prior dispensing systems, such as those described above.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention provides an apparatus for dispensing a liquid onto a substrate. To this end, the apparatus includes a horizontally-oriented manifold body having spaced apart front and rear surfaces and a lower surface extending between the front and rear surfaces. The lower surface is adapted to overlie at least a portion of the substrate. At least one dispensing module is mounted on the front surface of the manifold body and includes a discharge end for dispensing liquid onto the substrate. The discharge end is positioned proximate the lower edge of the front surface and the forward edge of the lower surface. At least a substantial portion of the lower surface of the manifold body is angled in an upward direction from a location proximate the lower edge of the front surface to a location proximate the lower edge of the rear surface to progressively increase the distance between the lower surface and the substrate from front to rear when the front surface is vertically oriented and the substrate is horizontally oriented beneath the manifold body. The manifold body may include non-angled front and/or rear lower surface portions with the angled portion adjacent or intermediate the non-angled portion(s). The lower surface may be angled between approximately 10 degrees and approximately 45 degrees, but is preferably angled at approximately 30 degrees.  
         [0008]     The features and objectives of the present invention will become more readily apparent from the following Detailed Description taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     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.  
         [0010]      FIG. 1  is a perspective view of an exemplary liquid dispenser of the present invention;  
         [0011]      FIG. 2  is a cross-sectional view of the liquid dispenser of  FIG. 1  taken along line  2 - 2 ;  
         [0012]      FIG. 3  is a schematic view of a prior art liquid dispenser;  
         [0013]      FIG. 4  is a cross-section view similar to  FIG. 2  showing the substrate being angled. 
     
    
     DETAILED DESCRIPTION  
       [0014]     Referring to  FIG. 1 , there is shown an exemplary liquid material dispensing system  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 end surfaces  22 ,  24 .  
         [0015]     Several liquid dispensing modules  26  are secured to the front surface  14  of the manifold body  12  by fasteners  28 . The dispensing modules  26  may be on/off-type modules with internal valve structure ( FIG. 2 ) for selectively dispensing liquid material in the form of one or more filaments or beads. 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.  
         [0016]     Liquid material, such as hot melt adhesive, and pressurized process air are supplied to the individual modules  26  through the manifold body  12  to thereby dispense beads or filaments of the liquid material onto a substrate  30 . The substrate  30  is positioned along a moving conveyor system (not shown) that passes the substrate  30  beneath the lower surface  20  of the manifold body  12  and the dispensing modules  26  in a machine direction as indicated by the arrow. The substrate may have a panel configuration so as to span the length of the manifold body, as shown in  FIG. 1 . The invention, however, is not so limited and, as is known by those skilled in the art, the substrate may generally be any material to which an adhesive is to be applied including, for example, individual elastic strands. The dispenser  10  further includes liquid material heaters  32  and process air heaters  34  for heating the process air and liquid material. Filters  36  are installed in the manifold body  12  to filter out contaminants from the liquid material supplied to the modules  26 .  
         [0017]     Referring now to  FIG. 2 , there is shown a cross-sectional view of the liquid dispenser  10  of  FIG. 1 . Process air is supplied to the dispenser  10  from a source of pressurized air (not shown) and is routed to the individual modules  26  through a series of interconnected passages. Process air enters the dispenser  10  through an air inlet port  38  formed in the rear surface  16  of the manifold body  12 . A fitting  40  coupled to the air inlet port  38  facilitates the attachment of an air line connected to the pressurized air source. The process air is heated by heater  34 , such as that described in co-pending U.S. patent application Ser. No. ______ titled “Integral Manifold for Liquid Material Dispensing Systems,” having a reference number NOR-1181, Express Mail No. EV371410885US, filed on ______ and assigned to the assignee of the present invention. After being heated, the process air enters a distribution passage  42  extending through the manifold body  12  and along the direction parallel to the bank of liquid dispensing modules  26 . A plurality of air outlet passages  44  are formed in the front surface  14  of the manifold body  12  and intersect the air distribution passage  42  whereby process air may be provided from the air distribution passage  42  through the outlet passages  44  to each module  26  secured to the front surface  14  of the manifold body  12 . The outlet passages  44  terminate at process air outlets  46  in the front surface  14  of manifold body  12 . Each module  26  includes a process air inlet  48  which confronts and communicates with the process air outlet  46  when the dispensing modules  26  are secured to the front surface  14  of the manifold body  12 .  
         [0018]     With continued reference to  FIG. 2 , liquid material is supplied to the manifold body  12  through a fitting  50  coupled to a liquid material inlet port  52  at the rear surface  16  and/or side surface  22  of the manifold body  12 . The liquid inlet port  52  leads to a filter cavity  54  formed in the rear surface  16  of the manifold body  12  and sized to receive a filter  36  for removing contaminants from the incoming liquid material. The filter  36  has an O-ring  56  to seal the upper end of the cavity  54 . The filter  36  depicted in this embodiment is more fully shown and described in co-pending U.S. patent application Ser. No. ______, titled “A Filter Assembly for a Liquid Dispensing Apparatus,” having a reference number NOR-1184, Express Mail No. EV372583247US, filed on ______ and assigned to the assignee of the present invention. Liquid material enters the filter  36  through circumferentially spaced inlets  58  and circulates through the filter  36  whereafter filter liquid material exits toward the bottom  60  of the filter cavity  54 . Thereafter, the liquid material enters a liquid distribution passage  62  communicating with the filter cavity  54  and extending longitudinally along the manifold body  12 , adjacent the bank of liquid dispensing modules  26  and generally parallel to the process air distribution passage  42 . A plurality of liquid outlet passages  64  are formed into the manifold body  12  from the front surface  14  and intersect the liquid distribution passage  62  where by liquid material flows from the liquid distribution passage  62 , through the liquid outlet passages  64  and to each of the dispensing modules  26  mounted on the front surface  14  of the manifold body  12 . The liquid outlet passages  64  terminate at liquid outlets  66  in the front surface  14  of the manifold body  12 . Each module  26  includes a liquid inlet  68  which confronts and communicates with the liquid outlet  66  when the dispensing modules  26  are secured to the front surface  14  of the manifold body  12 . As more fully described in co-pending U.S. patent application Ser. No. ______, titled “Integral Manifold for Liquid Material Dispensing Systems,” having a reference number NOR-1181, Express Mail No. EV371410885US, filed on ______, as the liquid flows through the liquid passageways, including passageways  54 ,  62 ,  64 , the liquid is heated by liquid heater  32 . The liquid material travels through various liquid passages formed in dispensing modules  26  and is discharged from one or more liquid discharge orifices  70  in dispensing module  26 , as is known in the art.  
         [0019]     As previously discussed, the process air and liquid are heated by heaters  32 ,  34  in the manifold body  12  before being fed to the dispensing modules  26 . These heaters  32 ,  34  are often high power heaters and as a result cause the various surfaces of the manifold body  12  to become hot. As shown schematically in  FIG. 3 , prior art dispensing systems  88  typically have a manifold body  90  having a liquid distribution portion  90   a  and a process air distribution portion  90   b , positioned below the liquid distribution portion  90   a . The manifold body  90  has a lower surface  92  that confronts the substrate  94  and runs generally parallel to the substrate  94  as it passes beneath the manifold  90  and one or more dispensing modules  96  along a front surface  98  of the manifold body  90 . The dispensing end  100  of the dispensing modules  96  is typically adjacent the lower surface  92 . In order to control the accuracy of the deposited liquid onto the substrate  94 , the dispensing end  100  is positioned adjacent the substrate  94 . As a result, the lower surface  92  of the manifold body  90  is also positioned adjacent the substrate  94 . The hot lower surface  92  then heats the substrate  94  as it passes under the manifold body  90 , which may lead to several undesirable results, as previously discussed.  
         [0020]     As most clearly shown in  FIG. 2 , the present invention includes a lower surface  20  having at least a substantial portion  101  that is angled in an upward direction. The lower surface  20  may be angled in the upward direction from a front intersecting edge  104  of the lower edge of front surface  14  and the front edge of lower surface  20  to a rear intersecting edge  102  of the lower edge of rear surface  16  and the rear edge of lower surface  20 . Alternately, the lower surface  20  may include non-angled front and/or rear portions with the angled portion  101  adjacent or intermediate the non-angled portion(s). For instance, as shown in  FIG. 2 , lower surface  20  includes non-angled front portion  105  adjacent front intersecting edge  104  such that the angled portion  101  starts proximate the front surface  14 . In this way, the distance between the lower surface  20  and substrate  30  progressively increase from front to rear such that the intersecting edge  102  is above the intersecting edge  104  to create an open cavity  106 . When substrate  30  is fed beneath the manifold body  12 , such as along a horizontal plane, the distance between the substrate  30  and intersecting edge  104  is at a first distance and the distance between the substrate  30  and intersecting edge  102  is a second distance greater than the first distance. The increased distance between the lower surface  20  of the manifold body  12  and the substrate  30  reduces the heating of the substrate  30  by the manifold body  12 . Furthermore, the open cavity  106  permits increased air flow beneath the manifold body  12 , further reducing the effects of manifold heating on the substrate  30 . The lower surface  20  may be angled between approximately 10 degrees and approximately 45 degrees, but is preferably angled at approximately 30 degrees.  
         [0021]     As shown in  FIG. 4 , the open cavity  106  created by angling the lower surface  20  of the manifold body  12  allows the substrate  30 ( a ) to be moved past the dispensing modules  26  at an angle. This may be advantageous in some applications, such as when coating LYCRA strands using the V-notch dispensing module. In these applications, the angle at which the substrate  30 ( a ) approaches and moves past the dispensing modules  26  affects the efficient coating of the substrate with the liquid. As shown in  FIG. 4 , the manifold body  12  of the present invention, having the angled lower surface  20 , permits the substrate  30 ( a ), such as LYCRA strands, to pass by the dispensing modules  26  at an angle. For instance, the substrate  30 ( a ) may approach the dispensing modules  26  so as to be generally parallel to the lower surface  20  of the manifold body  12 .  
         [0022]     The open cavity  106  created by angling the lower surface  20  of the manifold body  12  has additional advantages. For instance, maintenance personnel now have increased access to the substrate  30  beneath the manifold body  12 . Thus if the substrate  30  requires aligning or other adjustments, one could access the substrate  30  beneath the manifold body  12  to perform the desired procedure while avoiding inadvertent contact with the manifold body  12 . Moreover, once production has begun, it is undesirable to move the manifold/dispensing module applicator relative to the substrate  30 , as this may affect the established deposition height, pattern and the repeatability of the deposition process. During maintenance of the dispensing modules  26 , the modules  26  are drained of liquid as they are being removed from the manifold body  12 . To do this without dripping any liquid on the substrate  30 , a drip pan (not shown) is typically used. In prior dispensing systems, such as that shown in  FIG. 3 , it is often difficult to get the drip pan under the dispensing module  96 , thus necessitating the movement of the applicator relative to the substrate  94 . In the present invention, however, the open cavity  106  permits increased access to the dispensing modules  26  so as to position a drip pan beneath the modules  26  without disturbing the applicator/substrate relative positions.  
         [0023]     While the present invention has been illustrated by the description of the various embodiments thereof, and while the embodiments have been described in considerable detail, it is 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.