Abstract:
A hot melt dispensing system includes a hopper, a delivery line, a shaker, and an air supply line. The hopper stores hot melt pellets and the delivery line delivers the hot melt pellets from the hopper. The shaker agitates the hot melt pellets. The air supply line supplies air that flows through the shaker to produce vibration and additionally flows through the delivery line to create a vacuum that draws the hot melt pellets through the delivery line.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/718,224, entitled “VACUUM AND SHAKER FOR A HOT MELT SYSTEM,” filed Oct. 25, 2012. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates generally to systems for dispensing hot melt adhesive. More particularly, the present disclosure relates to feed systems for hot melt systems. 
         [0003]    Hot melt dispensing systems are typically used in manufacturing assembly lines to automatically disperse an adhesive used in the construction of packaging materials such as boxes, cartons and the like. Hot melt dispensing systems conventionally comprise a material tank, heating elements, a pump and a dispenser. Solid polymer pellets are melted in the tank using a heating element before being supplied to the dispenser by the pump. Because the melted pellets will re-solidify into solid form if permitted to cool, the melted pellets must be maintained at temperature from the tank to the dispenser. This typically requires placement of heating elements in the tank, the pump and the dispenser, as well as heating any tubing or hoses that connect those components. Furthermore, conventional hot melt dispensing systems typically utilize tanks having large volumes so that extended periods of dispensing can occur after the pellets contained therein are melted. However, the large volume of pellets within the tank requires a lengthy period of time to completely melt, which increases start-up times for the system. For example, a typical tank includes a plurality of heating elements lining the walls of a rectangular, gravity-fed tank such that melted pellets along the walls prevents the heating elements from efficiently melting pellets in the center of the container. The extended time required to melt the pellets in these tanks increases the likelihood of “charring” or darkening of the adhesive due to prolonged heat exposure. 
         [0004]    The system for dispensing hot melt adhesive utilizes a container such as a hopper for holding solid polymer pellets for dispensation to the material tank for melting. During low humidity and other conditions, solid polymer pellets can become bunched together and/or may cling to the sides of the hopper in a manner that is not conducive to dispensing the pellets to the remainder of the hot melt system. 
       SUMMARY 
       [0005]    According to the present invention, a hot melt dispensing system includes a hopper, a delivery line, a shaker, and an air supply line. The hopper stores hot melt pellets and the delivery line delivers the hot melt pellets from the hopper. The shaker agitates the hot melt pellets. The air supply line supplies air that flows through the shaker to produce vibration and additionally flows through the delivery line to create a vacuum that draws the hot melt pellets through the delivery line. 
         [0006]    In another aspect of the present invention, a hot melt dispensing system includes a hopper, a delivery line, an integrated shaker and vacuum assembly, and an air supply line. The hopper stores hot melt pellets and the delivery line delivers the hot melt pellets from the hopper. The integrated shaker and vacuum assembly are connected to the delivery line. The air supply line is connected in series through the shaker to create vibration and through the vacuum assembly to apply suction to the hot melt pellets within the hopper. 
         [0007]    According to another aspect of the present invention, a method of operating a hot melt dispensing system comprising disposing hot melt pellets in a hopper and directing air along a path that produces agitation of the hot melt pellets in the hopper and produces a vacuum to draw pellets into a delivery line. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic view of a system for dispensing hot melt adhesive. 
           [0009]      FIG. 2A  is a perspective view of a first embodiment of a shaker and vacuum disposed on a wand. 
           [0010]      FIG. 2B  is a plan view of the shaker and vacuum of  FIG. 2A . 
           [0011]      FIG. 2C  is a sectional view of the shaker and vacuum of  FIG. 2A . 
           [0012]      FIG. 3  is a perspective view of a second embodiment of the shaker and vacuum disposed on a wand. 
           [0013]      FIG. 4  is a schematic view of a second embodiment of a system for dispensing hot melt adhesive. 
           [0014]      FIG. 5A  a perspective view of another embodiment of a shaker and vacuum mounted adjacent a hopper. 
           [0015]      FIG. 5B  is sectional view of the shaker and vacuum of  FIG. 5 . 
           [0016]      FIG. 5C  is a second sectional view of the shaker and vacuum of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  is a schematic view of one embodiment of system  10 , which is a system for dispensing hot melt adhesive. System  10  includes cold section  12 , hot section  14 , air source  16 , air control valve  17 , and controller  18 . In the embodiment shown in  FIG. 1 , cold section  12  includes container  20  and feed assembly  22 , which includes integrated device  23 , feed hose  26 , inlet  28 , and wand  37 . Integrated device  23  includes vacuum assembly  24  and shaker  25 . In the embodiment shown in  FIG. 1 , hot section  14  includes melt system  30 , pump  32 , and dispenser  34 . Air source  16  is a source of compressed air supplied to components of system  10  in both cold section  12  and hot section  14 . Air control valve  17  is connected to air source  16  via air hose  35 A, and selectively controls air flow from air source  16  through air hose  35 B to integrated device  23  and through air hose  35 C to motor  36  of pump  32 . Air hose  35 D connects air source  16  to dispenser  34 , bypassing air control valve  17 . Controller  18  is connected in communication with various components of system  10 , such as air control valve  17 , melt system  30 , pump  32 , and/or dispenser  34 , for controlling operation of system  10 . 
         [0018]    Components of cold section  12  can be operated at room temperature, without being heated. Container  20  can be a hopper for containing a quantity of solid adhesive pellets for use by system  10 . Suitable adhesives can include, for example, a thermoplastic polymer glue such as ethylene vinyl acetate (EVA) or metallocene. 
         [0019]    Feed assembly  22  connects container  20  to hot section  14  for delivering the solid adhesive pellets from container  20  to hot section  14 . Feed assembly  22  includes, feed hose  26 , integrated device  23 , and wand  37 . As shown in  FIG. 1 , vacuum assembly  24  and shaker  25  are combined as integrated device  23 , which is mounted to wand  37  adjacent to inlet  28  of wand  37 . Wand  37  and integrated device  23  (shaker  25  and vacuum assembly  24 ) are inserted into container  20 . Wand  37  extends from container  20  and connects to feed hose  26 . 
         [0020]    Compressed air from air source  16  and air control valve  17  is delivered to both shaker  25  and vacuum assembly  24 . The compressed air is first used to actuate shaker  25  to agitate the adhesive pellets and in some cases to vibrate container  20 . The agitation facilitates the settling of the solid adhesive pellets in container  20  as well as breaks apart bunched pellets before they reach vacuum assembly  24 . After use in shaker  25 , the compressed air is exhausted to operate vacuum assembly  24  to produce suction which induces the flow of the solid adhesive pellets through inlet  28 , wand  37 , and then through feed hose  26  to hot section  14 . Wand  37  and feed hose  26  are passages sized with a diameter substantially larger than that of the solid adhesive pellets to allow the solid adhesive pellets to flow freely therethrough. 
         [0021]    As illustrated, single air source  16  is used to supply both vacuum assembly  24  and shaker  25 . The vibration/agitation induced by shaker  25  breaks apart the bunched pellets and facilitates the settling of the pellets in container  20 . Settled pellets in container  20  more easily travel to vacuum assembly  24  for transport through feed assembly  22 . By utilizing supply air from single air source  16  in series connection through shaker  25  and vacuum assembly  24 , system  10  reduces energy consumption and system noise as well as simplifying system  10  by reducing part count including the need for additional air hoses and/or storage containers. 
         [0022]    Solid adhesive pellets are delivered from feed hose  26  to melt system  30 . Melt system  30  can include a container (not shown) and resistive heating elements (not shown) for melting the solid adhesive pellets to form a hot melt adhesive in liquid form. Melt system  30  can be sized to have a relatively small adhesive volume, for example about 0.5 liters, and configured to melt solid adhesive pellets in a relatively short period of time. Pump  32  is driven by motor  36  to pump hot melt adhesive from melt system  30 , through supply hose  38 , to dispenser  34 . Motor  36  can be an air motor driven by pulses of compressed air from air source  16  and air control valve  17 . Pump  32  can be a linear displacement pump driven by motor  36 . In the illustrated embodiment, dispenser  34  includes manifold  40  and dispensing module  42 . Hot melt adhesive from pump  32  is received in manifold  40  and dispensed via module  42 . Dispenser  34  can selectively discharge hot melt adhesive whereby the hot melt adhesive is sprayed out outlet  44  of dispensing module  42  onto an object, such as a package, a case, or another object benefiting from hot melt adhesive dispensed by system  10 . Dispensing module  42  can be one of multiple modules that are part of dispenser  34 . In an alternative embodiment, dispenser  34  can have a different configuration, such as a handheld gun-type dispenser. Some or all of the components in hot section  14 , including melt system  30 , pump  32 , supply hose  38 , and dispenser  34 , can be heated to keep the hot melt adhesive in a liquid state throughout hot section  14  during the dispensing process. 
         [0023]    System  10  can be part of an industrial process, for example, for packaging and sealing cardboard packages and/or cases of packages. In alternative embodiments, system  10  can be modified as necessary for a particular industrial process application. For example, in one embodiment (not shown), pump  32  can be separated from melt system  30  and instead attached to dispenser  34 . Supply hose  38  can then connect melt system  30  to pump  32 . 
         [0024]      FIG. 2A  shows a partially exploded perspective view of integrated device  23  and wand  37 .  FIG. 2A  shows a plane view of integrated device  23 .  FIGS. 2A and 2B , which are discussed concurrently, illustrate integrated device  23 , which includes shaker  25  and vacuum assembly  24  disposed together as a single unit. Shaker  25  includes housing  56  (formed by housing sections  56 A and  56 B), raceway  58 , ball  60 , fasteners  63 , air inlet  65  ( FIG. 2A ), and air outlet  66  ( FIG. 2A ). 
         [0025]    Housing  56  includes a cavity  61 A bounded by raceway  58 , which is adapted to receive ball  60 . Sections  56 A and  56 B of housing  56  are held together by fasteners  63 . Air inlet  65  ( FIG. 2B ) communicates with air hose  35 B ( FIG. 2A ) and extends through housing  56  to communicate with the outer radius of raceway  58 . Air outlet  66  ( FIG. 2B ) extends inward radially from raceway  58  into vacuum assembly  24 . 
         [0026]    In operation, compressed air travels from air source  16  ( FIG. 1 ) through air inlet  65  in housing  56  into cavity  61 A and travels along raceway  58 . The compressed air causes ball  60  to roll along the circumference of raceway  58 . The weight imbalance that results from the ball  60  rolling along raceway  58  induces vibration of shaker  25 . 
         [0027]      FIG. 2C  shows a cross-section of integrated device  23  and wand  37 . In addition to raceway  58 , ball  60 , cavity  61 A, and fasteners  63 , integrated device  23  includes cavity  61 B, first housing portion  56 A, insert  64 , second housing section  56 B, inlet  68 , standoff  69 , and outlet  70 . 
         [0028]    As shown in  FIG. 2C , first and second housing sections  56 A and  56 B comprise portions of housing  56  for shaker  25  as well as forming a housing for vacuum assembly  24 . Insert  64  is disposed between first and second housing sections  56 A and  56 B and forms a section of passageway through integrated device  23 . Standoff  69  extends from second housing potion  67 . 
         [0029]    Air outlet  66  ( FIG. 2B ) extends through housing  56  to communicate with cavity  61  radially outward of insert  64 . Thus, air outlet  66  ( FIG. 2B ) allows exhausted compressed air from shaker  25  to travel to vacuum assembly  24 . Passageway  67  extends through housing  56  from inlet  68  to outlet  70 . Inlet  68  is formed in second housing section  56 B and is adapted to receive adhesive pellets within container  20  ( FIG. 1 ). Passageway  67  extends from inlet  68  through second housing section  56 B, insert  64  and first housing section  56 A to outlet  70 . Outlet  70  is formed by first housing section  56 A and is adapted to connect to the end of wand  37 . Standoff  69  can contact container  20  ( FIG. 1 ) to provide for some space between inlet  68  and container  20 . This space allows pellets to travel to inlet  68 . 
         [0030]    In operation, compressed air is exhausted from cavity  61 A of housing  56  through air outlet  66  to cavity  61 B radially outward of insert  64 . As is illustrated in  FIG. 2C , in one embodiment vacuum assembly  24  comprises a Venturi vacuum. The Venturi vacuum is formed by the disposition of insert  64  (with smaller cross-sectional area) relative to first portion  62  (which has a larger cross-sectional area adjacent insert  64 ). In particular, the Venturi vacuum is characterized by a region where the passageway  67  from inlet  68  has a constant or slightly decreasing cross-sectional area. At the circumferential outlet of cavity  61 B (at the end of insert  64 ), the cross-sectional area of passageway  67  abruptly increases creating a diverging section within vacuum assembly  24 . Diverging section is disposed downstream of outlet of cavity  61 . A converging section (a region where passageway has a decreasing or constant cross-sectional area) is disposed downstream of diverging portion and extends substantially to outlet  70 . 
         [0031]    In operation, compressed air is exhausted from cavity  61 A of shaker  25  and flows to cavity  61 B. The compressed air then passes through diverging portion between the insert  64  and the first housing section  56 A. While passing through the diverging portion and then the converging portion, the compressed air is subject to the Venturi effect. As a result of this effect, the velocity of the compressed air (and the velocity of the adhesive pellets drawn through inlet  68  by the pressure differential caused by the flow of compressed air) is increased. The increased velocity that results from the Venturi effect allows vacuum assembly  24  to discharge the adhesive pellets effectively along the length of feed hose  26  ( FIG. 1 ). Further, in the present invention air flows in series from the shaker  25  to the vacuum assembly  24  to reduce energy consumption and system noise as well as simplifying system  10  by reducing part count including the need for additional air hoses and/or storage containers. 
         [0032]      FIG. 3  shows a perspective view of another embodiment of integrated device  123  and wand  147 . Integrated device  123  includes shaker  125  and vacuum assembly  124  disposed together as a single unit. Shaker  125  includes housing  156 , first raceway  158 A, ball  160 A, fasteners  163 , second raceway insert  158 B, and second ball  160 B. 
         [0033]      FIG. 3  illustrates shaker  125  with section  156 B of housing  156  and raceway  158  removed to illustrate the interior of shaker  125 . Housing section  156 A has a cavity  161 A bounded by first raceway  158 A, which is adapted to receive ball  160 A. Sections  156 A and  156 B of housing  156  are held together by fasteners  163 . Second raceway insert  158 B is shown exploded out from raceway  158 A and shaker  125 . Second raceway insert  158 B is sized for insertion into raceway  158 A and indeed can be inserted therein as desired. Prior to insertion of second raceway insert  158 B, ball  160 A is removed. Second ball  160 B is used in shaker  125  with second raceway insert  158 B, as second raceway insert  158 B is sized for use with second ball  160 B. 
         [0034]    Second raceway insert  158 B and second ball  160 B can be used in applications where large vibration from the shaker  125  is not desirable or not necessary. Such situations could occur, for example, in more humid environments where pellets are less apt to clump together and/or where the use of a smaller hopper is desirable. 
         [0035]    In operation with second raceway insert  158 B and second ball  160 B inserted, compressed air travels from a single air source through an air inlet (not shown) in housing  156  into inner cavity  161 A as defined by second raceway insert  158 B. The compressed air causes second ball  160 A to roll along the circumference of second raceway  158 A. The weight imbalance that results from the second ball  160 A rolling along second raceway  158 A induces vibration of shaker  125 . 
         [0036]      FIG. 4  is a schematic view of system  210 , which is a system for dispensing hot melt adhesive. System  210  includes cold section  212 , hot section  214 , air source  216 , air control valve  217 , and controller  218 . In the embodiment shown in  FIG. 4 , cold section  212  includes container  220  and feed assembly  222 , which includes vacuum assembly  224 , shaker  225 , feed hose  226 , and inlet  228 . In the embodiment shown in  FIG. 4 , hot section  214  includes melt system  230 , pump  232 , and dispenser  234 . Air source  216  is a source of compressed air supplied to components of system  210  in both cold section  212  and hot section  214 . Air control valve  217  is connected to air source  216  via air hose  235 A, and selectively controls air flow from air source  216  through air hose  235 B to vacuum assembly  224  and shaker  225  and through air hose  235 C to motor  236  of pump  232 . Air hose  235 D connects air source  216  to dispenser  234 , bypassing air control valve  217 . Controller  218  is connected in communication with various components of system  210 , such as air control valve  217 , melt system  230 , pump  232 , and/or dispenser  234 , for controlling operation of system  210 . 
         [0037]    Components of cold section  212  can be operated at room temperature, without being heated. Container  220  can be a hopper for containing a quantity of solid adhesive pellets for use by system  210 . Suitable adhesives can include, for example, a thermoplastic polymer glue such as ethylene vinyl acetate (EVA) or metallocene. 
         [0038]    Feed assembly  222  connects container  220  to hot section  214  for delivering the solid adhesive pellets from container  220  to hot section  214 . Feed assembly  222  includes vacuum assembly  224 , shaker  225 , and feed hose  226 . As shown in  FIG. 4 , vacuum assembly  224  is positioned adjacent to and communicates with container  220 . Shaker  225  is mounted to or adjacent to container  220  and vacuum assembly  224 . 
         [0039]    Compressed air from air source  216  and air control valve  217  is delivered to both shaker  225  and vacuum assembly  224 . The compressed air is first used to actuate shaker  225  to agitate the solid adhesive pellets and in some cases vibrate container  220 . As illustrated in the embodiment shown in  FIG. 4 , the vibration agitates the pellets and facilitates the settling of the adhesive pellets in the container  220  as well as breaks apart bunched pellets before they reach vacuum assembly  224 . After use in the shaker  225 , the compressed air is exhausted to operate vacuum assembly  224  to create a vacuum, which induces flow of solid adhesive pellets through inlet  228  of vacuum assembly  224  and then through feed hose  226  to hot section  214 . 
         [0040]    Feed hose  226  connects vacuum assembly  224  to hot melt section  214 . Feed hose  226  is a tube or other passage sized with a diameter substantially larger than that of the solid adhesive pellets to allow the solid adhesive pellets to flow freely through feed hose  226 . 
         [0041]    As illustrated, the same single air source  216  is used to supply both vacuum assembly  224  and shaker  225 . The vibration induced by shaker  225  agitates and breaks apart the bunched pellets and facilitates the settling of the pellets in container  220 . The settled non-clumped pellets are more easily drawn to vacuum assembly  224  for transport through feed assembly  222 . By utilizing supply air from the same air source  216  in series to operate both shaker  225  and then vacuum assembly  224 , system  210  reduces energy consumption and system noise as well as simplifying system  210  by reducing part count including the need for additional air hoses and/or air sources. 
         [0042]      FIG. 5A  shows an embodiment of shaker  225  and vacuum assembly  224  mounted to a feed portion  250  of container  220 . As shown in  FIG. 5A , shaker  225  and vacuum assembly  224  are illustrated without features such as air hose  235 B ( FIG. 4 ) and with feed hose  226  disconnected and only partially shown. Shaker  225  and vacuum assembly  224  comprise separate units with the shaker  225  mounted to the vacuum assembly  224 . As discussed previously, compressed exhaust air from shaker  225  is used to operate vacuum assembly  224 . 
         [0043]    Vacuum assembly  224  is connected to feed portion  250  of container  220 . This disposes shaker  225  in close proximity to container  220  such that vibrations generated by shaker  225  agitate the solid adhesive pellets, container  220 , as well as vacuum assembly  224 . The vibration induced by shaker  225  breaks apart bunched pellets and facilitates the settling of the pellets to feed portion  250  of container  220 . 
         [0044]      FIG. 5B  shows a first cross-section of vacuum assembly  224  and shaker  225 .  FIG. 5C  shows a second cross-section of vacuum assembly  224  and shaker  225  along a perpendicular plane to the cross-section of  FIG. 5A . As shown in  FIGS. 5B and 5C , shaker  225  is connected to vacuum assembly  224  by fitting  252 . Shaker  225  includes air inlet  254  ( FIG. 5B ), housing  256 , raceway  258 , and ball  260 . Vacuum assembly  224  includes first portion  262 , second portion  263 , and passageway  267  with insert  264 , inlet  266  ( FIG. 5B ), and outlet  268  ( FIG. 5B ). 
         [0045]    Air inlet  254  extends from housing  256  and communicates with air hose  235 B ( FIG. 4 ). Air inlet  254  communicates with inner cavity  261 A of housing  256  via an inlet passageway  255  ( FIG. 5A ) through the housing  256 . Inner cavity  261 A is bounded by raceway  258  and contains ball  260 . Inner cavity also communicates with an outlet passageway  257  ( FIG. 5A ), which extends through housing  256  to fitting  252 . 
         [0046]    In the embodiment shown, fitting  252  comprises a hollow nipple that extends between shaker  225  and vacuum assembly  224  and extends through first portion  262  to communicate with a cavity  261  ( FIG. 5B ) radially outward of insert  264 . Fitting  252  connects shaker  225  to vacuum assembly  224  and allows exhausted compressed air from shaker  225  to travel to vacuum assembly  224 . Inlet  268  ( FIG. 5B ) is adapted to connect to feed portion  250  of container  220  to receive adhesive pellets. Passageway  267  extends from inlet  268  through second portion  263 , insert  264  and first portion  262  to outlet  270 . Outlet  270  ( FIG. 5B ) is formed by first portion  262  and is adapted to connect to feed hose  226  ( FIG. 4 ) of feed assembly  222  ( FIG. 4 ). 
         [0047]    In  FIGS. 5B and 5C , shaker  225  is mounted to vacuum assembly  224 , however in other embodiments shaker  225  can be mounted at a distance from vacuum assembly  224 . For example, shaker  225  can be mounted directly to or within container  220  and exhaust air used to operate shaker  225  can pass through a length of hose or similar air line to be used to operate vacuum assembly  224 . 
         [0048]    In operation, compressed air travels from air source  216  ( FIG. 4 ) through air inlet  254  and inlet passageway  255  in housing  256  to inner cavity  261 A. The compressed air causes ball  260  to roll along the circumference of raceway  258 . The weight imbalance that results from the ball  260  rolling along raceway  258  induces vibration of shaker  225 . 
         [0049]    The compressed air is exhausted from inner cavity  261 A through outlet passageway  257  in housing  256 . The air passes through fitting  252  and through first portion  262  to the cavity  261 B radially outward of insert  264 . Similar to the embodiment of  FIG. 2C , in one embodiment vacuum assembly  224  comprises a Venturi vacuum and operates in the manner previously discussed in order to create suction and discharge the adhesive pellets effectively along the length of feed hose  226  ( FIG. 4 ). 
         [0050]    While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.