Abstract:
A free turning chilling wheel assembly for use with a hot melt dispenser affording quick disassembly for cleaning, inspection, repair or replacement, and having an outer ring with an inner bronze bearing to rotate about a stationary inner cooling chamber, which is sealed to avoid wear and leaks. The outer ring is chilled by fluid flowing through the chamber and the sides of the outer ring are shielded by shielding washers to avoid adhesive building up on the bearing surfaces and ends.

Description:
FIELD OF THE INVENTION 
     This invention relates to an improvement in the structure of a chill wheel. More particularly, the invention relates to an assembly which affords the circulation of chilled water against the inner part of an outer ring of the wheel assembly and an assembly which affords easy removal for cleaning, inspection, repair and replacement. 
     The present invention provides an improved cooling wheel to be used for applying a tape or string of tacky hot-melt adhesive to a substrate. In one aspect, the present invention is directed to a free turning ring assembly which is cooled by a chilled fluid running through a stationary chamber, chilling the outer ring to chill the molten or tacky adhesive and adhere it to the substrate. The cooling or chill wheel, as it is often called, normally follows a dispenser which heats and directs the tacky hot-melt tape or string to be applied toward the substrate. 
     DESCRIPTION OF THE PRIOR ART 
     The prior art includes examples of hot-melt adhesive applicators adapted to dispense a ribbon of hot melt adhesive tape or to dispense a string of hot melt adhesive toward a moving substrate, to apply the adhesive to the substrate. The hot melt adhesive is then pressed against the substrate by an applicating wheel intended to press the adhesive onto the substrate. Such an applicator is illustrated in U.S. Pat. No. 4,285,758 wherein the applicating wheel  75  provides means for cooling the bonded thermoplastic adhesive. The wheel  75  comprises a wheel or roller made of hard material such as steel. 
     The hub of the wheel could be cast from aluminum and be provided with a hardened steel tire, which could in turn be chrome-plated. The wheel  75  rotates about a shaft mounted to an auxiliary cooling assembly frame  77  which is pivotally mounted. The cooling is carried out by coating the wheel with a release agent liquid which is wicked onto the surface of the wheel. The wheel served to cool the adhesive completing the bond. When the thermoplastic stuck to the wheel a scraper blade maintained in contact with the cooling wheel was used to release the adhesive. 
     Another example of adhesive applicating wheels is illustrated in U.S. Pat. No. 4,925,521, wherein a band  100  extends about wheels  104  and  106  and is driven at the same speed as the conveyor  18  to press the tape strip  28  against the carton blank advanced by the conveyor  18 . In this machine the band  100  is heated to heat the tape to its application temperature as it passes beneath the band  100  on top of the carton. Here the carton acts as the heat sink to help cool and solidify the tape after it leaves the bonding assembly. Here the wheels  104  and  106  are supported on shafts by roller bearings and while  106  is driven, roller  104  is the idler driven by the band  100 . 
     A prior art applicating roller is disclosed in U.S. Pat. No. 5,662,767 and comprises a wheel  18  which rotates with supporting axle  68  and is mounted with bearings  70  at an end of the wheel support  20 . The axle  68  defines an inlet conduit  72  for conducting fluid into a rotating wheel chamber  74  and an outlet conduit  76  for conducting fluid away from the wheel chamber. An inlet tube  78  is threadably attached to an inlet fitting  80  and provides a source of cooling fluid to the wheel chamber  74  through the inlet conduit  72 . An outlet tube  82 , threadably attached to an outlet fitting  84  and inlet fitting  80  prevents fluid from leaking from the system. The wheel is cooled internally by the cooling fluid, which preferably is recirculated in a closed system. Grooves are formed on each side of the wheel proximate the peripheral surface  90  of the wheel. An axle cover  92  on each end of the axle  68  extends from the inlet fitting  80  and outlet fitting  84  of the axle toward the peripheral surface  90 . A tongue  94  projects from each axle cover  92  toward the wheel  18  and cooperatively engages the groove  88 . The axle cover  92  thus defines a smooth sloping surface  96  extending from the tongue  94  proximate the wheel to the inlet fitting  80  or outlet fitting  84  on the axle  68 . In the event the string  12  becomes dislodged from the application pathway the axle cover  92  prevents the string from winding onto the axle  68 . 
     In this known prior art, sealed roller bearings are used in an environment where dust, heat and water are present causing the same to eventually become wet and dirty and become less effective due to an increase in drag on the wheel and most chill wheels are not driven. Further, known water cooled chill wheels use rotating water or chilling fluid reservoirs, resulting in greater danger of leaking. 
     The present invention eliminates sealed bearings, rotating cooling chambers and the tendency for the adhesive to wind on the rotating shaft of the chill wheel causing build up and interruption of the rotation. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an assembly for a chill wheel that will have less interruptions in its continued use by the elimination of sealed bearings, rotating chilling fluid reservoirs, and exposed rotating axles that allow adhesive build up. Elimination of sealed bearings also eliminates inherent drag due to friction caused by rotating sealed bearings. 
     A chill wheel assembly according to the present invention comprises a shaft having an inboard end and an extended end portion. The extended end portion has a section of reduced diameter between the inboard end and the distal end portion and has means for forming passageways through the inboard end affording communication between the space formed by the reduced section and the proximal end of the shaft for allowing chilling fluid to circulate through the reduced section. A cylindrical stator sleeve, having an outer cylindrical surface and an inner cylindrical surface, is placed over the end portion to cover the reduced section of the shaft for forming an enclosed chamber. An outer ring having an external cylindrical surface and an internal bore, with a bearing sleeve frictionally fitted within the internal bore fits closely over the stator sleeve. A sealing washer is placed against the inboard end of the shaft and the outer ring and another sealing ring is placed against the other end of the outer ring, and means are provided for retaining the second washer on the distal end to hold the parts together. 
     The chill wheel assembly for use on an adhesive applicator comprises a support member and a shaft is joined to the support member and extends therefrom in a cantilever fashion. The shaft has an inboard, proximal end or head, and an axially extending end portion. The end portion has a section of reduced diameter forming a cavity between the head of the shaft and the distal end portion and has passageways through the head affording communication between the reduced section and the proximal end of the shaft. A cylindrical stator sleeve is placed over the end portion to cover the section of reduced diameter, the cavity, and form a chamber. The chamber can be used for circulating water. A first sealing washer is positioned over the end portion and the stator sleeve and against the face of the head. An outer ring, having an external cylindrical surface and an internal bore, and a cylindrical bearing sleeve member fitted within the internal bore, having an internal diameter to fit closely about the outer surface of the stator sleeve, to provide rotation the of outer cooling ring or wheel. A second sealing washer is positioned over the distal end of the end portion, and there are retaining means on the distal end of the shaft to hold the assembly together. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be described with reference to the accompanying drawing wherein like reference numerals in the several views refer to like parts and wherein: 
     FIG. 1 is a perspective view of the chill wheel assembly incorporating one form of the present invention; 
     FIG. 2 is a top plan view of the assembly of FIG. 1; 
     FIG. 3 is a side elevational view of a chill wheel assembly according to the present invention; 
     FIG. 4 is a back view, with broken lines to show hidden features; 
     FIG. 5 is a sectional view taken along line  5 — 5  of FIG. 4; and 
     FIG. 6 is an exploded view of the assembly showing the various parts of the illustrated assembly. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention provides an improved chill wheel assembly for use with adhesive dispensing and application equipment. The chill wheel assembly is used to press and apply the adhesive to a substrate. The adhesive is a hot melt adhesive tape or string of adhesive that has been heated before it is dispensed toward a substrate such as a plywood panel or carton material for example. The chill wheel is placed closely adjacent to the area where the adhesive meets the substrate to press the adhesive into contact with the substrate and to cool the adhesive contacting the chill wheel to maintain separation of the surface of the wheel from the adhesive so it bonds to the substrate. Preferably the chill wheel is placed downstream. 
     The chill wheel assembly  10  of the present invention comprises an outer ring member  11  having a cylindrical outer surface  12  for contacting the adhesive and substrate, which ring  11  is rotatably mounted on a shaft  15 . The shaft  15  is generally cantilever mounted and has a head  16  at the or inboard end and an outwardly projecting cantilevered shaft end portion  18 . In the illustrated example the head  16  is circular and has a given diameter. The head  16  could be square in axial cross section or have other shapes. The end extended portion  18  projects axially from a face on the head. The end portion  18  has a peripheral groove  19  adjacent to the distal end of the end portion  18  to receive a retainer clip  20 , which forms the retaining means for holding the assembly together. Spring clip  20  is the fastener which is expanded or opened and placed over the distal end and into the groove  19 . Alternative retaining means could be a thread and nut, hole and cotter pin or similar structure. The spring clip  20  takes up the least space. 
     The shaft member  15  has a pair of bores  21  and  22  forming passageways, see FIG. 5 and 6, extending therethrough and communicating with an area of reduced diameter along the shaft, formed by a deep peripheral groove  24  in the end portion  18  between the proximal end the distal end thereof, which groove  24  forms a chamber for the circulation of the chilling fluid. The groove  24  has curved surfaces to promote circulation within the area as will be shown later. Fluid is directed under pressure into one of the passageways  21 ,  22  and it flows around the chamber  24  and out the other passageway. The groove  24  is enclosed by a stator sleeve  25  which fits over the end portion  18  defining the enclosed chamber. Additional peripheral grooves  26  and  28  are formed in the end portion  18 , the first  26 , adjacent to the head  16  of the shaft  15  and the second  28  across the groove  24  from the first  26 . O-rings  30  are placed in the grooves  26  and  28  and are engaged by the stator sleeve  25  and cooperate with the stator sleeve  25  to form a fluid tight chilling chamber. The chamber can be used for circulating fluid such as water. The stator sleeve  25  and shaft  15  are formed of a material to avoid corrosion such as stainless steel, because they form part of the chilling chamber through which the chilling medium is pumped. 
     The outer ring  11  illustrated has a diameter of 2.75 inches (about 7 cm), a length of about 1 inches (2.54 cm) and a thickness of about 0.85 to 0.9 inch (2.16 to 2.3 cm) and is formed with one eighth inch deep (0.3 cm) continuous circumferential grooves  31  in the opposite axial ends. A cylindrical bearing sleeve member  35 , formed of bronze or a similar bearing material, is frictionally fit within the ring  11  and has an inner diameter to closely fit about the stator sleeve  25  to rotatably support the outer ring  11 . The two members  25  and  35  have varying outer and inner diameters respectfully within four or 5 thousandths (0.004 to 0.005 of an inch) (0.01 to 0.012 cm) to afford the relative free rotation between them with the relatively low amount of force placed against the outer surface  12  of the ring  11  by the substrate and adhesive. The outer ring  11  is formed of a metal with an electroless nickel plate. The outer ring  11  may be formed of a ceramic with a bronze sleeve. The shaft  15 , stator sleeve  25 , bearing sleeve and outer ring  11  should be formed of materials with good thermal conductivity. 
     Positioned adjacent to the inboard side and the outer side of the outer ring  11  are sealing washers  36  and  38 . As more clearly shown in FIGS. 5 and 6, the cross section of the sealing washers  36  and  38  are generally “T shaped” such that one axially extending flange of each washer  36 ,  38  fits in a groove  31  of the outer ring  11 . The hole in the center of the washers fits over the stator sleeve  25 . The sealing washer shield the rotary parts from contamination by the adhesive. Within the flange on the opposite sides of the sealing washers  36 ,  38  there is an axial recess to receive the head  16  of the shaft  15  and on the distal end a washer  41 . The washers  36 ,  38  are formed of a low coefficient of friction material but one which is stable and oliophobic, such as nylon or other plastic material. 
     The washers  36  and  38  may rotate freely on the stator sleeve or stationary sleeve  25  and the flanges on the washers that fit in the concentric grooves  31  on the outer ring  11  are shorter than the depth of the grooves and they have radial dimension that is less than the radial dimension of the groove  31 . The outer ring  11  can rotate free from engagement with the washers  36  and  38  or the washers can rotate freely with the outer ring if the outer ring contacts either washer. In this way, the washers  36  and  38  serve to cover or shield the outer ring  11  and bearing sleeve  35  where they rotate on the stator sleeve  25  from contamination by the adhesive. 
     The washer  41  on the other hand is formed of steel which may or may not be plated or equivalent, and fits against the retainer clip  20  of the wheel assembly  10 . 
     In the drawing the wheel assembly  10  is supported from a manifold  45  having fluid transmitting bores  51  formed therein connected at one end to traverse bores  48  and  49  and at the exterior to water line fittings  46  and  47 , see FIG.  4 . The inboard end of the shaft member  15  is sealed against the manifold  45 . Counter bores are formed on the face of shaft  15  about the axially parallel bores  21  and  22  to receive two small O-rings  50 . These two small O-rings  50  seal the transverse bores  48  and  49  in the manifold  45  and the axially parallel bores  21  and  22  of the shaft member  15  to define good seals about the bores defining the chilling fluid passageways. The manifold  45  is preferably formed of aluminum or similar material. The material should permit changes in temperature without disturbing the O-ring seals  50 . 
     The manifold  45  is illustrated as one type of support member for the shaft  15 . The manifold can also have different shapes. Alternatively, the support member for the shaft supporting the freely rotating outer ring may be an arm. Such an arm may be secured to the head of the shaft. This could include an extension to the head extending away from the extended end portion  18 , and threading this extension to receive, a first insulating washer, the support arm, another insulating washer, a steel washer and a threaded locking nut. The locking nut serving to hold the head on the arm. The insulating washers serving to block heat from the adhesive dispensing device, to which the arm is connected, from reaching the chilling wheel, or outer ring  11 . In assemblies such as this the fittings  45 ,  47  for the chilling fluid would be connected directly to the head and to outboard ends of the bores  21  and  22 . 
     The manifold  45  is joined to the face of the shaft  15  at the proximal end by bolts (not shown), or other fasteners, extending through openings  52  in the manifold  45  and into the face of the head  16  of the shaft member  15 . 
     Having described the invention with reference to the accompanying drawing, it is contemplated that changes can be made in shape, size and materials without departing from the spirit or scope of the invention as set forth in the appended claims.