Abstract:
A module or dispenser for dispensing at least one liquid filament onto a moving substrate includes a nozzle body having a liquid supply port, a liquid discharge portion or end, and a liquid discharge passage having an orifice in fluid communication with the liquid supply port. The liquid discharge passage extends along an axis and the opening is shaped asymmetrically about the axis to provide a controlled directional movement of the liquid filament in a desired direction. The asymmetric shape may be formed by a notch or a chamfer or a stepped portion intersecting with the liquid discharge passage, or combinations of these features, or in other manners.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a liquid material dispensing apparatus and, more specifically, to an applicator or module for dispensing controlled patterns of liquid filaments and a nozzle having a asymmetric liquid discharge orifice for controlling the direction in which the liquid filament is discharged. 
     BACKGROUND OF THE INVENTION 
     Many reasons exist for dispensing liquids, such as hot melt adhesives, in the form of a thin filament or strand with a controlled pattern. Conventional patterns used in the past include patterns involving a swirling effect of the filament by impacting filament with a plurality of jets of air. This is generally known as controlled fiberization or CFTυ in the hot melt adhesive dispensing industry. Controlled fiberization techniques are especially useful for accurately covering a wider region of a substrate with adhesive dispensed as single filaments or as multiple side-by-side filaments from nozzle orifices having small diameters, such as on the order of 0.010 inch to 0.060 inch. The width of the adhesive pattern placed on the substrate can be widened to many times the width of the adhesive filament itself. Moreover, controlled fiberization techniques are used to provide better control of the adhesive placement. This is especially useful at the edges of a substrate and on very narrow substrates, for example, such as on strands of material such as Lycra used in the leg bands of diapers. Other adhesive filament dispensing techniques and apparatus have been used for producing an oscillating pattern of adhesive on a substrate or, in other words, a stitching pattern in which the adhesive moves back-and-forth generally in a zig-zag form on the substrate. 
     Conventional swirl nozzles typically have a central adhesive dispensing orifice surrounded by a plurality of air orifices. The adhesive dispensing orifice is centrally located on a protrusion which is symmetrical in a full circle or radially about the adhesive dispensing orifice. Another advantageous controlled pattern dispenser, disclosed in U.S. patent application Ser. No. 09/571,703 filed on even date herewith and the disclosure of which is hereby incorporated herein by reference, locates the adhesive dispensing orifice on a wedge-shaped member and includes air orifices located in generally surrounding relation at the base of the wedge-shaped member. 
     One particular problem with conventional nozzles configured to produce a controlled pattern of adhesive by impacting the adhesive filament with air is that manufacturing imperfections or contaminates within the liquid adhesive discharge orifice may cause the discharging filament to be misdirected as the filament exits the discharge orifice. Since controlled fiberization techniques such as this are often utilized for applications requiring a high degree of accuracy, any unintended deflection of the adhesive filament upon discharge must be minimized. As a general illustration, FIGS. 1A and 1B schematically illustrate prior art swirled adhesive patterns  10   a,    10   b,    10   c  on a substrate  12  and a liquid discharge passage  20  of a nozzle  22  with a defect  24  shown in exaggerated form in FIG.  1 B. This defect  24  causes the discharging filament  26  of adhesive to be deflected as shown in FIG.  1 B. As shown in FIG. 1A, one result can be that adjacent patterns  10   a,    10   b  of swirled adhesive filaments on a substrate, which are intended to be evenly spaced as shown in phantom lines, become unevenly spaced as shown in solid lines. FIG. 1C illustrates another problem of the prior art. In this figure a nozzle  21  is dispensing multiple strands or filaments of adhesive  26   a,    26   b,    26   c.  Liquid strands or filaments  26   a,    26   b  are interfering with each other or tangling with each other as they exit nozzle  21  due, for example, to defect  24  shown in FIG.  1 B. These occurrences can be undesirable or even intolerable for certain applications and are experienced in air assisted filament dispensing and non-assisted filament dispensing. 
     For the reasons stated above, as well as other reasons, it would be desirable to provide apparatus and methods which minimize or override the effect of manufacturing defects or other reasons for adhesive filaments to be deflected upon discharge and, therefore, to produce more controllable and predictable liquid adhesive filament patterns. 
     SUMMARY OF OF THE INVENTION 
     Generally, the present invention provides a liquid dispensing module including a dispenser or module body having a liquid supply passage. In the preferred embodiment, the liquid is hot melt adhesive, but the invention is applicable to other liquids as well, such as other polymeric thermoplastic liquids. A nozzle body is coupled to the module body and includes a liquid supply port, a liquid discharge portion or end and a liquid discharge passage having an orifice or opening in fluid communication with the liquid supply port. The liquid supply port is in fluid communication with the liquid supply passage of the module body. The liquid discharge passage of the nozzle body extends along an axis and the liquid discharge orifice has an asymmetric shape about the axis to provide a controlled directional movement of the liquid filament dispensed from the liquid discharge orifice. 
     In general, since the invention provides the above-mentioned controlled directional movement of the liquid filament upon discharge, this controlled movement overcomes potential deflections caused, for example, by manufacturing defects or contaminants within the discharge orifice itself or by other sources of unintended deflective movement of the filament. In the preferred embodiment, the substrate is moving beneath the dispenser or module and the controlled movement produced by the asymmetric shape of the orifice or opening at the discharge end is in the machine direction. As the liquid adhesive filament discharges from the orifice, the filament is purposely deflected in the machine direction. This helps prevent sideward deflection of a swirled adhesive pattern or other liquid filament pattern. In this manner, sideward spacing of adjacent patterns of adhesive is maintained as intended without tangling of adjacent patterns, or better edge control is achieved and, generally, more accurate positioning of the liquid is achieved side-to-side beneath the dispenser in a direction transverse to the substrate movement. 
     In various embodiments of the invention, the controlled movement of the discharged liquid filament and, more particularly, the asymmetric shape of the orifice, is achieved in different manners. As one feature, the notch intersects the liquid discharge passage and causes deflection of the adhesive in the direction of the notch. As another alternative, the discharge portion of the nozzle body may include a chamfer intersecting with the liquid discharge passage. As another alternative, the discharge portion may include a stepped portion intersecting with the liquid discharge passage. 
     These and other features, advantages and objectives of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1A is an elevational view of swirled adhesive filament patterns illustrating problems of the prior art. 
     FIG. 1B is a cross-sectional view of the discharge end of the nozzle shown in FIG. 1A illustrating in exaggerated form a manufacturing defect within the liquid discharge passage. 
     FIG. 1C is a perspective view illustrating a filament tangling problem with the prior art. 
     FIG. 2 is a perspective view illustrating a liquid adhesive dispenser or module having a nozzle constructed in accordance with one embodiment of the invention. 
     FIG. 3A is a rear elevational view of the nozzle shown in FIG.  2 . 
     FIG. 3B is a cross-sectional view taken generally along line  3 B— 3 B of FIG.  3 A. 
     FIG. 3C is a bottom view of the nozzle illustrated in FIG.  3 A. 
     FIG. 3D is a bottom view similar to FIG. 3C, but illustrating an alternative air discharge orifice configuration. 
     FIG. 4A is a cross-sectional view similar to FIG. 3B, but illustrating another alternative embodiment of the invention. 
     FIG. 4B is a bottom view of the nozzle shown in FIG.  4 A. 
     FIG. 5A is a rear elevational view of another alternative nozzle constructed in accordance with the invention. 
     FIG. 5B is a cross-sectional view taken generally along line  5 B— 5 B of FIG.  5 A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2 generally illustrates a representative example of a dispenser module  30  usable in connection with this invention. It will be appreciated that many other alternative dispenser configurations may be used as well. Module  30  may, for example, be part no. 309637, which is sold by Nordson Corporation of Westlake, Ohio, and which is the assignee of the present invention. Dispenser module  30  includes a body  32  having an upper cap  34  secured to body  32  by fasteners  36  and including fasteners  38  which may be used to secure module  30  to a support, such as to adhesive and air manifold structures (not shown). A lower member  40  is secured to dispenser body  32  by fasteners  42 ,  44  and receives a nozzle assembly  50  constructed in accordance with the invention. Lower member  40  supplies a liquid, such as hot melt adhesive, as well as pressurized air to nozzle assembly  50  from respective liquid and air supply passages  51 ,  53 . Nozzle assembly  50  generally includes a nozzle  52  and a cover plate  54 . Cover plate  54  is secured to nozzle  52  by fasteners  56  and these fasteners  56  further couple nozzle  52  and cover plate  54  to lower member  40 . As disclosed in more detail, for example, in U.S. Pat. No. 5,934,520, a valve within dispenser body  32  and lower member  40  selectively supplies adhesive to nozzle  52  in an on/off fashion. The disclosure of U.S. Pat. No. 5,934,520 is hereby fully incorporated by reference herein. The valve may be operated pneumatically or electrically, or through other mechanisms, the details of which are not necessary to a full understanding of the present invention. Nozzle  52  includes a plurality of adhesive filament discharge passages  60  with orifices or openings  60   a.  Three passages  60  are shown in FIG. 2, however, a greater or lesser number of dispensing passages  60  may be provided instead. 
     FIG. 3A illustrates the rear face  52   a  of nozzle  52  which faces lower member  40  of dispenser module  30  (FIG.  2 ). Holes  62 ,  64  receive fasteners  56  previously described with regard to FIG.  2 . Holes  70 ,  72  comprise pressurized air supply ports which communicate with one or more pressurized air supply passages therein to deliver pattern air adjacent the discharged liquid filaments as discussed below. A recess  80  communicates with liquid supply ports  82 ,  84 ,  86  for supplying liquid hot melt adhesive to respective discharge passages  60 . Discharge passages  60  are each formed in identical wedge-shaped members  88 . Wedge-shaped members  88  are each positioned between a pair of angled surfaces  87 ,  89  which angle upwardly toward the base of each wedge-shaped  88  as shown in FIG.  3 A. An exit at a peak or apex  88   a  thereof as shown in FIG.  3 B. Apex  88   a  may be formed with a flat or may be relatively sharpened as shown in FIG.  3 A. 
     As shown best in FIG. 3B, a flat or stepped portion  90  is formed starting at one end  88   b  of wedge-shaped member  88  and extending toward liquid discharge passage  60  until it intersects therewith. In this manner, the opening or orifice  60   a  of passage  60  at apex  88   a  is shaped in an asymmetric manner about the longitudinal axis of passage  60 . A liquid adhesive filament  100  will exit discharge orifice  60   a  and upon exiting, will deflect in the direction of apex  88   a,  i.e., to the left as shown opposite to the machine direction MD. With nozzle  52  oriented as shown, apex  88   a  will ideally be aligned with the machine direction MD so that the deflection will occur in a direction parallel to the machine direction MD. It will be appreciated that machine direction MD may be in the exact opposite direction as well and that filament  100  may be discharged in other directions than vertically downward as shown. 
     FIG. 3D represents an alternative nozzle  52 ′. FIGS. 3C and 3D illustrate alternative configurations of respective liquid discharge passages  60  and air discharge orifices  102 . Orifices  102  receive pattern air from ports  70 ,  72  (FIG. 3A) and discharge the air in streams toward a liquid filament exiting a respective orifice  60   a  to form a filament pattern, such as a swirl pattern. It will be appreciated that, for clarity, each of these orifices is illustrated with an exaggerated, enlarged diameter. In typical hot melt adhesive dispensing operations in which a swirling pattern of adhesive is desired, for example, the respective liquid discharge orifice sizes will range from 0.010 inch to 0.060 inch. The respective air discharge orifice diameters will also range from 0.010 inch to 0.060 inch. It will be appreciated that other liquid and air discharge orifice configurations and arrangements will be possible in accordance with the inventive concepts and, moreover, that the present invention is applicable to those applications that do not use air to deflect or otherwise control the pattern of adhesive discharging from the liquid discharge orifice. 
     FIGS. 4A and 4B illustrate another alternative nozzle  150  including a generally frustoconical-shaped projecting portion  152 . A liquid discharge passage  154  having an orifice  154   a  extends centrally through projecting portion  152  along an axis. In accordance with the invention, a chamfer  158  is formed at the discharge end of liquid discharge passage  154  and projecting portion  152 . This chamfer  158  preferably does not intersect with liquid discharge passage  154  for more than half the circumference thereof, as shown in FIG.  4 B. In accordance with the general concepts of this invention, this forms a radially asymmetrical discharge opening  154   a  of passage  154 . One side of passage  154  will therefore exit projecting portion  152  at a higher level, when oriented vertically as shown in FIG. 4A, than the opposite side of passage  154 . It will be appreciated that other orientations are possible and will achieve similar objectives. Thus, a filament of liquid, such as hot melt adhesive  162 , will immediately deflect upon exiting passage  154  in the direction of chamfer  158  and, when oriented as shown, in the machine direction MD. As further shown in FIG. 4B, air discharge orifices  168 ,  170  may be provided for forming a specific pattern of adhesive, such as a swirling pattern. For this purpose as well, additional air discharge orifices may be provided in generally surrounding relation to liquid discharge orifice  154   a.    
     FIGS. 5A and 5B illustrate another alternative embodiment of a nozzle  200  constructed in accordance with the principles of the present invention. As with the first described embodiment, nozzle  200  may include fastener holes  202 ,  204 , air supply ports  206 ,  208 , and adhesive supply recess  210  and multiple adhesive supply ports  212 , all similar to the embodiment described in FIG.  3 A. Separate frustoconical projecting portions  214  extend from a lower surface of nozzle  200  and include liquid discharge passages  216  and respective openings or orifices  216   a.  A notch  220  is formed in each projecting portion  214  and intersects liquid discharge passage  216  as shown best in FIG.  5 B. In a manner corresponding to the principles of the previous embodiments, this notch  220  causes a liquid filament  226  to deflect in the direction of notch  220  immediately upon exiting liquid discharge orifice  216   a.  Again, notch  220  is preferably oriented to face a direction parallel to the machine direction MD. When oriented as shown, this creates a higher exit point for filament  226  in a direction parallel to the machine direction MD and causes the intentional deflection as shown in FIG.  5 B. 
     While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments has been described in some detail, it is not the intention of the Applicants 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 various features of the invention may be used alone or in numerous combinations depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims, wherein