Abstract:
A material dispensing apparatus, for use with a circular workpiece, includes a nozzle having a wedge-shaped aperture. The nozzle is attached to a dispenser body, and a solenoid valve is operable to start and stop material flow through the apparatus. A rotatable turntable is preferably provided below the nozzle for rotatably supporting a workpiece. In a method of adding a flowable material to a workpiece, having a circular outline, the workpiece is supported on a rotatable support member, and a dispenser nozzle, having a wedge-shaped outlet aperture, is positioned over a selected portion of the annular workpiece, with a wide end of the aperture adjacent an outer side wall of the workpiece. Then, a valve is opened to allow material to flow through the nozzle. After the material flow begins, the annular workpiece is rotated to deposit the material substantially evenly thereon, and after the annular workpiece has been rotated an amount in a range between 350 and 370 degrees, the valve is closed to stop the material flow through the nozzle.

Description:
[0001]    This patent application claims priority under 35 USC 119(e) on provisional patent application No. 60/247,448. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the invention  
           [0003]    The present invention relates to a material dispensing apparatus for dispensing a flowable material. More particularly, the present invention relates to a material dispensing apparatus as described, including a nozzle having a wedge-shaped aperture, and to a method of using same.  
           [0004]    2. Description of the Background Art  
           [0005]    Many devices are known for use in material handling. Examples of some known material handling devices include U.S. Pat. Nos. 4,569,628, 4,650,234, 4,802,816, 4,811,834, ,481,794, and 5,145,388.  
           [0006]    Certain filter-forming machinery is sold by Midmac Systems, Inc. of Saint Paul, Minn., and is shown and advertised on the Internet at http://www.midmac.com/FilterTech.htm.  
           [0007]    Examples of some known patents relating to filter manufacture include U.S. Pat. Nos. 2,739,916, 3,164,506, 3,306,794, 3,948,712, 4,626,307, 4,747,816, 5,028,330, and 5,698,059.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides a material dispensing apparatus, for dispensing a flowable material into a circular workpiece. The dispensing apparatus includes a dispenser body, and a dispenser nozzle having a wedge-shaped aperture. The nozzle includes a nozzle body having a flow passage therethrough, with an inlet and an outlet.  
           [0009]    Preferably, the nozzle inlet is formed as a hollow cylinder, having female threads formed therein, to allow the nozzle to be threadably and rotatably attached to the dispenser body.  
           [0010]    In a preferred embodiment, the nozzle body flow passage includes a bore formed in the nozzle body in communication with the inlet, and a substantially flattened channel in fluid communication with the bore, the substantially flattened channel having a wedge-shaped cross section corresponding to the nozzle outlet.  
           [0011]    The tip of the nozzle is tapered, and the nozzle has a substantially flattened end face formed in the tip thereof, with the outlet aperture formed in the substantially flattened end face.  
           [0012]    The substantially flattened end face is disposed at an angle with respect to an adjoining surface of the nozzle, to facilitate and direct fluid flow therefrom.  
           [0013]    The present invention also relates to a method of adding a flowable material to a workpiece having a circular outline.  
           [0014]    A first step in the method hereof involves supporting a workpiece on a rotatable support member, the workpiece having a circular outline.  
           [0015]    A subsequent step in the method hereof involves positioning a dispenser nozzle, having a wedge-shaped outlet aperture, over a selected portion of the workpiece, with a wide end of the aperture adjacent the outer side wall of the. This step may be accomplished by moving the nozzle to bring it near the workpiece, or by moving the workpiece into proximity to the nozzle.  
           [0016]    Once the dispenser nozzle has been positioned over the selected portion of the workpiece, a valve is opened to allow material to flow through the nozzle.  
           [0017]    After the material flow begins, the workpiece is rotated to deposit the material substantially evenly on the workpiece, and after the workpiece has been rotated an amount in a range between 350 and 370 degrees, the valve is closed to stop the material flow through the nozzle.  
           [0018]    Accordingly, it is an object of the invention to provide a method and apparatus for dispensing a flowable material into a circular workpiece.  
           [0019]    It is a further object of the present invention to provide a method and apparatus capable of dispensing a substantially constant thickness of material throughout the workpiece.  
           [0020]    For a more complete understanding of the present invention, the reader is referred to the following detailed description section, which should be read in conjunction with the accompanying drawings. Throughout the following detailed description and in the drawings, like numbers refer to like parts. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is a simplified top plan view of an assembly line according to the present invention;  
         [0022]    [0022]FIG. 2 is an end perspective view of a handling and transfer station according to the invention, which is a part of the assembly line of FIG. 1;  
         [0023]    [0023]FIG. 3 is a birds-eye perspective view of the handling and transfer station of FIG. 2;  
         [0024]    [0024]FIG. 4 is a simplified side view of part of a gripper apparatus, which is a component shown in FIGS.  2 - 3 , showing a juxtaposed progressive time-lapse sequence of positions of the opposed jaws thereof, during full travel from open to closed;  
         [0025]    [0025]FIG. 5A is a side plan view of a gripper apparatus of FIGS.  2 - 3 ;  
         [0026]    [0026]FIG. 5B is a top plan view of a gripper apparatus of FIGS.  2 - 3 ;  
         [0027]    [0027]FIG. 6 is an exploded perspective view of the gripper apparatus of FIGS.  2 - 5 , showing component parts thereof;  
         [0028]    [0028]FIG. 7 is a perspective view of an end cap application station, which is also part of the assembly line of FIG. 1, and also showing an inductive heating apparatus;  
         [0029]    [0029]FIG. 8 is a perspective view of an unloading station, which is another part of the assembly line of FIG. 1;  
         [0030]    [0030]FIG. 9 is a side plan view of the unloading station of FIG. 8;  
         [0031]    [0031]FIG. 10 is a side plan view of an adhesive dispensing apparatus;  
         [0032]    [0032]FIG. 11 A is a top plan view of a nozzle according to the invention which is usable with the dispensing apparatus of FIG. 10, showing internal passages in phantom;  
         [0033]    [0033]FIG. 11B is a side plan view of the nozzle of FIG. 11A;  
         [0034]    [0034]FIG. 11C is an end plan view of the nozzle of FIG. 11A;  
         [0035]    [0035]FIG. 11D is a diagram showing origin of the aperture of the nozzle in FIGS. 11A  11 C;  
         [0036]    [0036]FIG. 12A is a side plan view of an emplacement applicator assembly which is part of the end cap application station of FIG. 7, showing the orientation thereof at a first time;  
         [0037]    [0037]FIG. 12B is a side plan view similar to FIG. 12A, showing the orientation of the emplacement applicator at a second time, subsequent to that of FIG. 12A;  
         [0038]    [0038]FIG. 12C is a bottom plan view of the emplacement applicator assembly of FIGS.  12 A- 12 B;  
         [0039]    [0039]FIG. 12D is a top plan view of an annular clamping jig which is part of the emplacement applicator assembly of FIGS.  12 A- 12 C;  
         [0040]    [0040]FIG. 12E is a top plan view of a hollow end cap which fits into the clamping jig of FIG. 12D;  
         [0041]    [0041]FIG. 13 is a side plan view of the application station of FIG. 7, showing a juxtaposed progressive time-lapse sequence of positions of the two opposed end cap emplacement applicators;  
         [0042]    [0042]FIG. 14A is a side plan view of an end cap pre-cure station which is another portion of the assembly line of FIG. 1;  
         [0043]    [0043]FIG. 14B is a top plan view of the end cap pre-cure station of FIG. 14A;  
         [0044]    [0044]FIG. 14C is an inner end plan view of the end cap pre-cure station of FIG. 14A;  
         [0045]    [0045]FIG. 15 is a side plan view of the unloading station of FIGS.  8 - 9 ; and  
         [0046]    [0046]FIG. 16 is a series of method steps in a method of making a filter cartridge according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0047]    Referring now to the drawings, an overview of an assembly line is shown generally at  10  in FIG. 1, from an overhead birds-eye vantage point. The assembly line of FIG. 1 operates according to a process involving a number of sequentially performed steps. The assembly line  10  depicted in the drawing is provided for assembling fluid filter cartridges  17  (FIG. 8). The filter cartridges  17  are, in turn, used as components in manufacturing spin-on oil filter assemblies, during which the cartridges are encased in hollow housings.  
         [0048]    Each filter cartridge  17  includes a porous filter element  20  (FIG. 2) having a center tube  22  therein, and two metal end caps  93 ,  94 , which are affixed to opposite ends of the filter element with a plastisol adhesive. A first end cap  93  (FIG. 12E) has a hollow opening  95  formed centrally therethrough, and a second end cap  94  (FIG. 7) is closed at the central area thereof.  
         [0049]    A series of spindles  12  may be seen at the lower right quadrant of FIG. 1. Each spindle  12  has an associated trough  14  for supporting a cylindrical filter element  20  from below. (The filter elements  20  are intentionally omitted from FIG. 1 for purposes of simplifying the illustration, but a filter element is shown in FIGS.  2 - 3 ). The spindle  12  and trough  14  move together as an assembly  15  on a continuous-loop feed conveyor  11 . As seen best in FIG. 2, although made of accordion-pleated filter material, each filter element  20  is made substantially in the shape of a hollow cylinder, and is associated with a foraminous center tube  22  for reinforcing placement in the center thereof.  
       Transfer to Gripper Assembly  
       [0050]    Referring now to FIGS.  1 - 3 , the spindle/trough assembly  15  moves laterally on the feed conveyor  11 , and transports the filter element  20  over towards a gripper assembly  30 , which is initially in an open configuration to receive the filter element. The gripper assembly  30  provides a handling and transfer apparatus for a cylindrical workpiece, such as the filter element  20 . The gripper assembly  30  is temporarily held in the open configuration thereof by pressure from an actuator  92  on a cam follower bearing  88  (FIG. 3).  
         [0051]    The construction, component parts, and function of the gripper assembly  30  will be  1  discussed in further detail below.  
         [0052]    A paddle arm  16  pushes the filter element  20 , and associated center tube  22 , out of the trough  14 , through a half-pipe guide sleeve  19 , and into an upwardly curving lower jaw  34  of the gripper assembly  30 . A computer-controlled servo motor  25  activates the paddle arm  16  to push the filter element  20  a measured distance forward, which moves it through the guide sleeve  19  and into the gripper assembly lower jaw  34 , so as to center the element therein.  
         [0053]    An adjustable stop member  50  may, optionally, also be provided, to limit the distance that the filter element  20  can travel forward from the guide sleeve  19 .  
         [0054]    The paddle arm servo may be programmed to push a different stroke distance, for a different-sized filter element, at the push of a button. Referring in particular to FIGS.  2 - 5 , the opposed jaws  32 ,  34  of the gripper assembly  30  are curved in opposite directions and define a cylindrical space therebetween when closed, to closely conform to the tubular shape of the filter element  20 .  
         [0055]    Each of the jaws  32 ,  34  includes a plurality of spaced-apart teeth  36 , as shown, which mesh together when the jaws are closed, and which allow the jaws to interlock with one another, as they close around a filter element  20 . As best seen in FIG. 5A, the outermost tips of the teeth  36  are tapered to help align a filter element  20  therebetween.  
         [0056]    The teeth  36  mesh together to form a continuous reference surface while the unconstrained workpiece is grasped thereby. The intermeshing of the teeth  36  allows the jaws  32 ,  34  to constrain a previously unconstrained cylindrical workpiece to a matching cylindrical reference surface formed by the meshing of the two jaws. The tapered shape of the outermost tips of the teeth  36  help to correctly orient the cylindrical filter element  20  between the jaws  32 ,  34  without appreciable risk of pinching or damaging the element during orientation thereof.  
         [0057]    Those in the art will understand that a simpler approach, using two opposed semi-cylindrical half shells could conceivably be used, instead of the depicted jaws  32 ,  34 ; however, this type of arrangement would not provide the advantage of properly orienting the workpiece that the intermeshing tapered teeth  36  give, but instead, would run the risk of damaging the workpiece, if it is not properly oriented.  
         [0058]    Referring now to FIG. 6, it will be seen that in a particularly preferred embodiment hereof, each of the individual jaws  32 ,  34  may be made as a subassembly, and may be separated into component parts, i.e., a hinge portion and a jaw extension. The respective extensions  35 ,  37  include the teeth  36 , and the extensions are quickly releasable and interchangeable from their respective hinge portions  38 ,  40 , to allow a user to remove the extensions and substitute replacement extensions (not shown) of a different size. This permits rapid line change-over to fit another size of filter being assembled, as appropriate.  
         [0059]    The gripper assembly  30  is capable of accurately and repeatably holding any diameter workpiece to within 0.002 inches relative to the fixed center point shown in FIG. 5A. The center point remains at the center of the jaw extensions  35 ,  37 , regardless of what size jaw extensions are used. This constant center point facilitates adjusting the apparatus for a different sized filter when the jaw extensions are changed. The fixed center point eliminates the need for any height changeover for the emplacement applicators and the inductive heaters, other than servo length setting, or for any adjustment to the unloader. These additional components will be explained at a later point herein.  
         [0060]    The gripper assembly  30  is one of a series of interconnected gripper assemblies which are substantially identical to one another. The multiple gripper assemblies  30  are mounted on a transport conveyor  33  (FIGS. 1, 9). The transport conveyor  33  is a chain loop conveyor that continuously cycles around, with pauses at the individual work stations.  
         [0061]    The opposed jaws  32 ,  34  of an individual gripper assembly  30  will be in a first horizontal orientation thereof, as shown in FIGS. 2, 3, and  5  during the initial pick-up of a workpiece, but will then rotate 90 degrees, to the vertical orientation shown in FIG. 7, with the tips of the extensions pointing upward, as the gripper assembly moves along. Later in the assembly process, the gripper assembly  30  will again rotate 90 degrees to a second horizontal orientation thereof, for transferring the workpiece to a drop-off station  100 , as shown in FIGS.  8 - 9 . After drop-off, each of the closed gripper assemblies  30  will cycle back along the underside of the transport conveyor  33 , to the point where it receives a new filter element  20  from the feed conveyor  11 , to begin the cycle again. Three of the above-described primary orientations of the gripper assembly  30  may be seen in FIG. 9.  
         [0062]    (At this point, ongoing discussion of the movement of an individual filter element  20 , along the assembly line  10 , will be temporarily suspended while the structure and function of the gripper assembly is described in detail. The discussion of the movement of the filter element along the assembly line  10  is resumed in the subsection entitled ‘Closing the Jaws of the Gripper Assembly’.)  
       Structure and Function of the Gripper Assembly  
       [0063]    In the illustration of FIG. 6, a particular preferred embodiment of the gripper assembly  30  is shown in exploded perspective view. It will be understood that the depicted embodiment is intended to illustrate, rather than to limit the invention. The gripper assembly  30  includes the upper and lower jaws  32 ,  34  as noted, and each of the upper and lower jaws is separable into a hinge portion and an extension, as outlined above.  
         [0064]    The gripper assembly  30  also includes an inner cage  46 , a spring  48 , an outer cage  52 , and a pivot pin  54 . Each of these components of the gripper assembly  30  will be discussed in further detail herein.  
       The Gripper Jaws  
       [0065]    The jaws  32 ,  34  each include a plurality of spaced apart teeth  36 , as noted, and each of the jaw hinge portions  38 ,  40  includes a plurality of spaced apart flanges  56 .  
         [0066]    In the depicted embodiment, each of the jaw hinge portions  38 ,  40  has a cylindrical actuator shaft  58 ,  60 , respectively, extending outwardly thereon. The cylindrical actuator shafts  58 ,  60  each carry a bearing  62 ,  63 , respectively, rotatably mounted thereon.  
         [0067]    In a particularly preferred embodiment of the invention, the respective shaft and bearing combinations  58 ,  62  and  60 ,  63  are provided as integral cam follower bearing assemblies.  
         [0068]    For heavy duty applications, a second set of actuator shafts and bearing assemblies, which are identical to those shown in the drawing, may be provided on the parallel opposite side surfaces of the hinge portions  38 ,  40 . For a standard duty application, a single set is sufficient.  
         [0069]    Each of the jaw hinge portions  38 ,  40  also has a hollow bore  64 ,  66 , respectively, formed through the flanges  56 , for receiving the pivot pin  54  therein, when the flanges are intermeshed with one another and placed within the inner cage  46 .  
         [0070]    Preferably, the jaw extension  35  has alignment studs  42  (FIG. 3) attached to and extending away from the innermost face thereof, and these alignment studs include enlarged heads, as shown. The alignment studs  42  may be inserted into wide portions of key slots  44  (FIG. 6) of the hinge portion  38 , and then the extension  35  can then be slidably moved with respect to the hinge portion, in the direction of the key slots  44 , to lock the hinge portion and extension together in an aligned configuration. The lower extension  37  is attached to the lower hinge portion  40  in similar fashion.  
         [0071]    The jaw extensions  35 ,  37  are slid until they will not move any further, at which point a respective spring-loaded detent button  45 ,  47 , attached to the cover plate, as shown, fits engagingly into a corresponding hollow cylindrical cavity (not shown) appropriately formed in the inward-facing surfaces of the jaw extensions. The hinge portions  38 ,  40  are provided with appropriate conventional hardware to allow an operator to selectively release the detent buttons  45 ,  47  when the operator wishes to detach the jaw extensions  35 ,  37  from the hinge portions.  
       The Inner Cage  
       [0072]    The inner cage  46  provides a housing for the jaws  32 ,  34 , and with the respective flanges  6  of the jaw hinge portions  38 ,  40  intermeshed with one another, the jaws  32 ,  34  fit together inside of the inner cage  46 .  
         [0073]    The inner cage  46  has a generally box-like shape, which is open at two sides and an end thereof, as shown. The inner cage  46  includes two opposed side walls  68 ,  70  connected to a backing plate  72 , substantially at right angles thereto. As viewed from above, in the orientation shown in FIG. 6, the inner cage  46  has a substantially U-shaped outline. The space between the side walls  68 ,  70 , on each side of the inner cage  46 , is preferably left open, to allow outward movement of the jaw extensions  35 ,  37  without any interference or resistance by the inner cage structure.  
         [0074]    For heavy duty applications, both of the side walls  68 ,  70  may be provided with the structure and reinforcing bars shown on the near side wall  70  in FIG. 6. Otherwise, the inclusion of such structure on only one side wall  70  is sufficient.  
         [0075]    In the depicted embodiment, each of the two opposed side walls  68 ,  70  of the inner cage  46  has a reinforced edge portion at the top thereof, as shown, and these reinforced edge portions have hollow bores  69 ,  71  formed respectively therethrough. The inner cage includes a solid backing plate  72 , which interconnects the side walls  68 ,  70 . In the depicted embodiment, the backing plate  72  has a circular groove  74  inscribed therein, to provide a first seat for the spring  48 .  
         [0076]    In a particularly preferred embodiment of the invention, the side edges of the inner cage side walls  68 ,  70  have track extensions  75  (FIGS. 5A, 5B) attached thereto, to guide sliding movement of the outer cage  52  thereon.  
       The Outer Cage  
       [0077]    The outer cage  52  includes a generally rectangular frame  76 , formed of four flattened frame sections connected to one another.  
         [0078]    In the depicted embodiment of the invention, the outer cage  52  is provided with four micro-linear bearings  55  (FIG. 5B) attached thereto with conventional fasteners. The micro-linear bearings  55  are provided to roll along the tracks  75  of the inner cage, to smooth out and facilitate sliding movement of the outer cage  52  along the inner cage  46 .  
         [0079]    Those in the art will realize that other alternative, equivalent structure may be provided to guide slidable movement of the outer cage on the inner cage.  
         [0080]    As shown in FIGS. 5A and 6, one frame section  80  of the outer cage  52  has a pair of linearly spaced apart guide slots  82 ,  84  formed therethrough. In between the guide slots, the frame section  80  has a post  86  affixed thereto, and extending outwardly thereon. Preferably, this post  86  has a cam follower bearing  88  (FIG. 3) rotatably attached thereto. In a particularly preferred embodiment of the invention, the post  86  and bearing  88  are provided together as a cam follower bearing assembly.  
         [0081]    For heavy duty applications, the side of the outer cage  52  opposite the frame section  80  may also have guide slots formed therein which mirror the guide slots  82 ,  84  of the frame section  80 . For standard duty applications, a single pair of guide slots is sufficient.  
         [0082]    A central crossmember  78  bridges across, and is removably attached to, two of the sections making up the frame  76 . In the depicted embodiment, the central crossmember  78  has a circular groove  79  inscribed in the surface thereof, which faces toward the backing plate  72 , to provide a second seat for the spring  48 .  
       Construction of the Gripper Assembly  
       [0083]    In assembling the gripper assembly, the crossmember  78  is lined up between, and oriented parallel to the side walls  68 ,  70  of the inner cage  46 , as shown. The outer cage is then placed over the inner cage, with the side walls  68 ,  70  inside of the frame  76 , to slidably interconnect the inner and outer frames, with the spring  48  extending between the crossmember and the inner cage backing plate  72 .  
         [0084]    The jaw hinge portions  38 ,  40  are then placed into the outer cage  52 , with the flanges  56  aligned and intermeshed with one another, and with the bearings  62 ,  63  installed in the guide slots  82 ,  84  of the outer cage frame section  80 , as seen in FIG. 5A. The jaw extensions are then connected to their corresponding hinge portions, as previously described.  
         [0085]    After the jaws  32 ,  34  are installed inside the inner cage, with the bores  64 ,  66  aligned with one another and with the bores  69 ,  71  of the inner cage, the pivot pin  54  is inserted through, and is anchored in the hollow bores  69 ,  71  of the inner cage side walls  68 ,  70 , to pivotally attach each of the jaws  32 ,  34  to the inner cage  42 . The actuator posts  58 ,  60  extend outwardly from the inner cage, between the bars thereof, and the bearings  62 ,  63  fit slidably inside of the guide slots  82 ,  84  of the outer cage.  
         [0086]    (The present discussion now returns to the progression of a filter element  20  along the assembly line  10 .)  
       Closing the Jaws of the Gripper Assembly  
       [0087]    Referring now to FIG. 3, it will be seen that after the filter element  20  has been placed in the lower jaw  34  of the gripper assembly  30 , the actuator  92  releases its pressure on the cam follower bearing  88 , which is connected by the post  86  to the outer cage  52 . This movement of the actuator  92  releases the force which has been compressing the spring  48  in the inner cage  46 . The outward pressure of the spring  48  pushes the outer cage  52  away from the base plate  72 , and moves the outer cage relative to the inner cage. The outward movement of the outer cage puts pressure on the shafts  58 ,  60  of the jaw hinge sections, via the bearings  62 ,  63 .  
         [0088]    Since the flanges  56  of the jaw hinge portions are pivotally, but not slidably attached to the inner cage  46  by the pivot pin  54 , movement of the shafts  58 ,  60  moves the opposed jaws  32 ,  34  around the pivot pin  54 , until the teeth of the jaws intermesh and the jaws contact one another, clamping the filter element therebetween.  
         [0089]    It is a feature of the present invention that the default position of the jaws  32 ,  34  is in the closed position illustrated in FIG. 5, due to the mechanical action of the spring  48 .  
         [0090]    This design has the advantage of being able to continue to accurately hold a workpiece even in the event of a power interruption, because of the relatively unencumbered construction and arrangement of the gripper assembly  30 . No external power source is required for the gripper assembly  30  to continue to securely and accurately hold a workpiece therein, once the workpiece has been picked up. The force of the spring  48  will continue to urge the jaws  32 ,  34  closed, until a countervailing force is applied to overcome the spring force.  
       The End Caps  
       [0091]    After the filter element  20  has been securely grasped, the gripper assembly  30  then moves the filter element, via the transport conveyor  33 , to an end cap mounting station, shown in FIG. 7, where two end caps are simultaneously placed on opposite ends of the filter element. This simultaneous placement is illustrated in FIG. 13.  
         [0092]    Only the second end cap  94  is shown in FIG. 7, but the first end cap  93  looks substantially similar to the second end cap in the drawing, with the exception that the central portion of the first end cap has a hollow aperture  95  (FIG. 12E) formed through the center portion thereof, which is necessary for the proper functioning of the filter cartridge assembly  17 . It will therefore be understood that the following description of the second end cap  94  also applies to the first end cap  93 , with the single difference that the first end cap  93  has a centrally located hollow aperture  95  therein, radially internally of the inner edge portion thereof.  
         [0093]    In the practice of the present invention, the end caps are preferably made of metal. Each end cap  93 ,  94  has a circular outline as seen in the top plan view of FIG. 8, and includes a flattened O-shaped base  96  and inner and outer side walls  97 ,  98  integrally formed with the base and extending outwardly therefrom and substantially transverse thereto. Together, the base  96  and edge portions  97 ,  98  form an annular tray, and define a hollow receptacle  99  therebetween for holding a measured amount of adhesive, and for receiving a peripheral end of the filter element  20  therein.  
         [0094]    At a location spaced away from the area where the gripper assembly picks up the filter element  20 , an operator loads individual end caps into a belt-driven feeder conveyor  23  (FIG. 1), which sequentially transfers the end caps to a rotary indexer  200 . The belt-driven feeder conveyor uses two parallel continuous-loop belts, running on two pairs of spaced-apart pulleys, to move the end caps in the desired direction.  
         [0095]    Separate and simultaneously operating end cap feed lines  27 ,  29  (FIG. 1) are provided for each type of end cap  93 ,  94 . The end caps are mechanically placed in sequence on the feeder conveyors  23 , with the end cap openings  99  facing up.  
         [0096]    The different stages in the simultaneous treatment of two end caps  93 ,  94  on a parallel set of conveyors, rotary indexers  200 , and emplacement applicators  220  is substantially identical on both end cap feed lines  27 ,  29  (FIG. 1), except for the final orientation of the respective emplacement applicators, which are mirror images of one another, as shown in FIG. 13.  
         [0097]    Accordingly, a description of the end cap movement along only one of the two feeder conveyors is necessary here, and it will be understood that each operation is being concurrently performed on a second end cap using a corresponding second system, of like design.  
         [0098]    It is also notable that the end caps  93 ,  94  are moving along their respective conveyors  23 , and then are transferred to their respective emplacement applicators, at the same time that the filter element is being picked up by the gripper assembly and transferred to the application station. The adhesive-filled end caps and filter element meet at the application station, as will be further described.  
       The Dispensing Operation  
       [0099]    The end caps move on the conveyor to a rotating circular dial plate  202  of a rotary indexer  200 , where they are filled with uncured plastisol resin (not shown).  
         [0100]    The rotary indexer  200  has four identical openings  204  formed in the dial plate  202  thereof, and only three of these openings are used at any given time in the assembly process.  
         [0101]    First, the feed conveyor  23  feeds an end cap  93  to the dial plate  202  for initial pickup.  
         [0102]    The opening  204  of the dial plate  202  is provided with a ledge  206  for supporting placement of an end cap thereon, and the feeder conveyor  23  feeds an end cap into the opening and on top of the ledge.  
         [0103]    The dial plate  202  then rotates 90 degrees through a horizontal plane, to move the end cap to a fill station  210  (FIG. 10).  
         [0104]    At the fill station  210 , a linear actuator temporarily lifts the end cap off of the dial plate  2 . A dispenser  211  is selectively fed measured batches of plastisol adhesive, under controlled pressure conditions, through an adhesive flow circuit. Flow of the adhesive is precisely controlled by enabling and disabling an electrically controlled solenoid valve.  
         [0105]    The end cap is lifted from the dial plate by a linear actuator, having a rotatable turntable thereon. Adhesive flow is initiated when the end cap reaches the level of a dispensing nozzle  212 . Each operative end cap is individually rotated a full 360 degrees on the turntable, while the dial plate is held steady below the end cap, and a dispensing nozzle  212  precisely dispenses the needed amount of plastisol therein. After one full rotation, flow through the nozzle  212  is stopped, and the linear actuator then retracts and replaces the end cap in the opening of the dial plate  202 .  
         [0106]    The Dispensing Nozzle  
         [0107]    The dispensing nozzle  212  is formed having an outlet formed as a substantially trapezoidal aperture  130  therein, to correctly distribute the material in a graduated and increasing fashion, from the inside diameter of the end cap out to the outside diameter thereof. As best seen in FIGS.  11 A- 11 D, the diameter of the nozzle aperture  130  is based on a wedge-shaped section cut out of a ring shape, using substantially radial straight lines, intersecting the ring to define the top and bottom sides of the wedge. Nozzle aperture width is chosen to correspond to the width of the end cap recess  99  for a particular filter cartridge, and three different examples of nozzle aperture widths are shown in FIG. 11.  
         [0108]    Most preferably, the wedge shape of the nozzle aperture is calculated to be proportional to the circumferences of the inside and outside diameters of the end cap. This compensation is necessary, because more material is needed around the end cap outside diameter than is needed around the inside diameter, due to the greater distance around the outside diameter. This relationship is shown in FIG. 11.  
         [0109]    Specifically, the ratio of the nozzle aperture width at the outside diameter to the nozzle aperture width at the inside diameter is (π) (outside diameter) divided by (π) (inside diameter) equals (O.D./I.D.) The relationship is linear between these points, so the gap simply narrows uniformly from the O.D. to the I.D.  
         [0110]    As best seen in FIG. 12, the nozzle  212  is formed as a hollow body  132  from a hollowed-out piece of material, which is preferably a metal. The nozzle  212  has a flow passage formed therethrough, including a cylindrical bore  134  formed therein defining an inlet  136 . The flow passage enters an end surface of the nozzle body  132  via the bore  134 , continues inwardly until it is about halfway through the body, and then makes a substantially right-angle turn, as shown. After turning, the flow passage communicates with a substantially flattened channel  140  formed in the outlet end of the nozzle body. The flattened channel  140  has a wedge-shaped cross section corresponding to the nozzle aperture  130 . A pair of mounting holes  142 ,  144  may be formed through the body  132  of the nozzle, but the mounting holes are not required.  
         [0111]    The nozzle inlet is formed as a hollow cylinder, having female threads formed therein, to allow the nozzle to be threadably and rotatably attached to the dispenser.  
         [0112]    The tip of the nozzle is tapered, as shown, and the nozzle has a substantially flattened end face formed in the tip thereof, with the outlet aperture formed in the substantially flattened end face. The substantially flattened end face is disposed at an angle with respect to an adjoining surface of the nozzle, to facilitate and direct fluid flow therefrom.  
         [0113]    The result of this nozzle design is that a ribbon of adhesive is dispensed with the same thickness at the inside diameter of the end cap and the outside diameter thereof, as well as in between, in a single rotation of the end cap. This is a significant improvement over the previously known adhesive dispensing apparatus, which required both multiple rotations of the end cap, and subsequent “combing” of the dispensed adhesive, to achieve a uniform adhesive thickness within the end cap. It will be evident from the above discussion that the wedge-shaped nozzle aperture provides for a faster and more efficient dispensing operation than was previously possible.  
         [0114]    A material dispensing apparatus of the above-described type is not limited to use for filling an annular workpiece, as disclosed herein, but may also be adapted for use in filling a circular workpiece, if appropriately dimensioned.  
         [0115]    When the end cap has been filled with the correct amount of plastisol, the dial plate spins another 90 degrees, and a ‘walking beam’ then picks up the filled end cap from the rotary indexer and places the end cap in a holding fixture, shown supporting the end cap  94  in FIG. 7.  
         [0116]    The adhesive is allowed to stabilize in the holding fixture for one quarter rotation of the dial plate  202 , after which, the filled end cap is placed into a substantially annular constrictable clamping jig  222 , of an emplacement applicator assembly  220 .  
       The Clamping Jig  
       [0117]    The substantially annular clamping jig  222  (FIG. 9) includes a cylindrical body attached to the applicator plate, and a circular collar which is movably mounted on the cylindrical body. The circular collar is made up of three individual arcuate segments  224 ,  226 ,  228 , respectively, which are movably attached to the cylindrical base. Each of the arcuate segments  224 ,  226 ,  228  can be reciprocally and radially moved, with respect to the center point of the clamping jig, in the direction of the two-headed arrows shown in FIG. 12D. Each segment of the clamping jig is substantially identical to the other segments, and when moved close together into edge-to edge contact with one another, the three segments  224 ,  226 ,  228  define a circular hollow therebetwen for holding an end cap  93  therein. The circular collar includes an inwardly tapered inner edge  225 , for compressively forcing the peripheral outermost edge of the filter element inwardly as the collar moves therepast. The tapered inner edge  225  is provided to ensure that the entire circumference of the peripheral edge fits within the hollow end cap receptacle, inside the outer side edge of the end cap.  
         [0118]    The end cap application station  230  includes a stationary support base  232 , and a guide member  234  which is fixedly attached to the stationary support base. In the preferred embodiment of the invention, the guide member  234  includes a pair of parallel opposed, substantially vertical first and second guide plates  236 ,  238 , respectively. Each of the guide plates  236 ,  238  has a respective guide groove  239 ,  240  formed therein. The guide grooves  239 ,  240  face inwardly towards one another, and are substantially similar in shape and size. Each of the guide grooves  239 ,  240  defines a ramp, such as that shown at  242 , therein.  
         [0119]    Those skilled in the art will realize that an equivalent alternative design could be made with opposed wedge-shaped ramps (not shown) rather than the guide plates of the depicted embodiment, and that such ramps, where used, would accomplish substantially the same result in substantially the same way.  
         [0120]    As best seen in FIG. 12, in the preferred embodiment of the invention, the guide groove  240  is formed in a stretched-out forward or reverse “S” shape, as shown. This preferred guide groove construction includes a substantially horizontal first section  244  at its lowermost part; a second section  245 , which is disposed at an angle with respect to the first section, and which defines the ramp  242  at the bottom surface thereof; and a substantially horizontal third section  246  at the top part of the groove.  
         [0121]    The guide grooves produce both the linear and rotary motion of the emplacement applicator assembly  220  using only one axis of movement. The elongated upper horizontal third section  246  of the guide groove accommodates varying filter sizes, without requiring a mechanical changeover of the guide member  234 . This is greatly simplified from the previously known assemblies for providing a combined linear and rotary motion.  
         [0122]    A push bar  250  is situated above the support base  232  of the application station  230 , and the push bar is linearly and reciprocally slidable with respect to the stationary support base. A servo motor  252  is provided to power sliding movement of the push bar  250 . The push bar  250  has a drive plate  254  affixed thereon, at the top thereof. The drive plate  254  has an integrally attached spacer  256  affixed thereto and extending upwardly thereon, and the spacer has an axle shaft  257  passing horizontally therethrough, to provide a pivot connection between the drive plate and a back plate  260  of an emplacement applicator  220 , as will be further described below.  
       The Emplacement Applicator  
       [0123]    In the application station depicted in FIG. 7, an emplacement applicator  220  is provided for placing an end cap  94  on an end of the filter element  20 . As previously noted, and as illustrated in FIG. 13, an emplacement applicator is provided for each end cap  93 ,  94 . The drive plate  254  may be viewed as part of the emplacement applicator  220 . The emplacement applicator  220  includes a back plate  260  which is pivotally attached to the drive plate  254  via the axle shaft  257 , by virtue of a hollow passage formed through appropriate sections thereof. Although the back plate  260  may be pivotally moved from a flat position to an upright vertical position as shown in FIG. 12, for purposes of convenience, the back plate will be described in the upright orientation thereof shown in FIG. 7. It will be understood that the relative descriptive terms for the different parts of the back plate  260  are used to illustrate, rather than to limit the invention.  
         [0124]    The back plate  260  has an upper part  262  shaped like a capital letter “D” turned to rest on its flat edge, and a lower part which is operatively pivotally attached to the drive plate  254  at a pivot connection  255 . The lower part of the back plate  260  consists of two legs  264 ,  266  which are integral with the upper part  262  and which extend downwardly therefrom on opposite sides thereof. Each of the legs  264 ,  266  has a transverse flange  268 ,  270 , attached thereto and extending forwardly thereon, and the front part of each flange has a cylindrical bore formed therein, which receives the axle shaft  257  therethrough, to pivotally mount the back plate  260  to the upper end of the drive plate spacer  256 .  
         [0125]    At the base of the back plate  260 , each of the legs  264 ,  266  has a respective cam follower bearing assembly  265 ,  267  attached to an inner edge portion of the transverse spacer  256 , which is spaced away from the pivot connection  255  and from the axle shaft  257 . The races of the cam follower bearing assemblies  265 ,  267  are disposed resting on the ramps of the respective guide members, as shown in FIG. 7.  
         [0126]    It will be understood from the foregoing, and from a review of the relevant drawings, that when the push bar  250  forces the emplacement applicator assembly  220  inwardly, the cam follower bearing assemblies  265 ,  267  ride up the respective ramps of the guide grooves  239 ,  240 , thereby pivoting the back plate  260  around the pivot connection  255 , (defined by the axis shaft  257  pivotally interconnecting the drive plate vertical boss  256  with the back plate  260  at the transverse flanges  268 ,  270 ). This causes the applicator back plate  260  to move from a substantially horizontal orientation to a substantially vertical orientation thereof.  
         [0127]    The above-described arrangement of the emplacement applicator  220  allows it to reliably and reproducibly emplace an end cap  94  on the end of a filter element  20  with a great degree of precision, reliability and reproducibility so as to provide a more standardized filter cartridge assembly than was heretofore possible.  
         [0128]    [0128]FIG. 13 illustrates various positions of the two opposed emplacement applicators  219 ,  220 , as they move toward simultaneously emplacing the end caps  93 ,  94  on the filter element  20 .  
         [0129]    Intermediate positions of the applicators are shown in phantom. The end caps  93 ,  94  are omitted from FIG. 13 for purposes of simplifying the illustration.  
         [0130]    Once the two end caps  93 ,  94  have been emplaced on opposite ends of the filter element the end cap clamping jig  222  is activated to move the segments radially outwardly, to release the end caps therefrom. The opposed push bars are then retracted, by activating two synchronized servo motors, connected to threaded shafts which pass through the push bars, to move the emplacement applicators  219 ,  220  back to the horizontal orientation thereof, where they can pick up the next two end caps  93 ,  94 .  
         [0131]    Due to the thixotropic nature of uncured plastisol adhesive, there is no significant problem with flow of uncured adhesive downwardly within the end cap in the short time between the placement of the end cap on the filter element and the pre-cure operation.  
       Pre-Cure  
       [0132]    After the end caps  93 ,  94  have been emplaced on the filter element  20 , the transport conveyor  33  advances the gripper assembly  30  to a pre-cure station  280  (FIG. 14), where it is placed between two inductive heating assemblies  282 ,  284 , which incorporate electromagnetic field (EMF) generators. Inductive heating assemblies are relatively well known and are commercially available; however, it is applicant&#39;s understanding that inductive heaters have not been used in connection with a filter cartridge assembly apparatus and method.  
         [0133]    The inductive heating assemblies  282 ,  284 , are respectively mounted on opposite ends of a double ball screw  286  for simultaneous motion in opposite directions, and they move into close proximity to the end caps. The double ball screw  286  is operated by a servo motor  288 . As shown in the drawing, the double ball screw includes a shaft which is rotatably mounted in a support structure. A first end of the shaft is threaded in a first direction, such as with a standard right-hand thread, while the opposite end of the shaft is threaded in a second direction which is the opposite of the first direction. Matching female threads are provided inside each of the heating assemblies  282 ,  284  corresponding to the part of the shaft that the heating assembly is mounted on. In this way, spinning the shaft, in a single direction of rotation, causes the heating assemblies  282 ,  284  to move in opposite directions.  
         [0134]    Each of the inductive heating assemblies  282 ,  284 , then generates a high-frequency electromagnetic field surrounding its respective associated end cap  93 ,  94 . The electromagnetic field induces current flow within the metal of the end cap, thereby generating heat and rapidly heating the end cap to partially cure the plastisol resin therein, sufficiently to form a bond between the end cap and the filter element  20 , and to fix the position of the end cap with respect to the filter element.  
         [0135]    The inductive heating assemblies  282 ,  284 , do not themselves become hot, which has two distinct advantages, as compared to a conventional heating element, in the method according to the present invention. First, the cycle time is very quick, generally less than two seconds per part. Second, in the event that some plastisol adhesive should inadvertently get on the inductive heating assemblies  282 ,  284 , there will not be any bonding of an end cap on to one or the other of inductive heating assemblies, possibly leading to a production stoppage, as there might otherwise be with a conventional heating element that had become contaminated with plastisol.  
         [0136]    This pre-cure step is important for several reasons. It fixes the position of the end caps  93 ,  94  with respect to the paper element  20 , and this relative positioning carries through to the finished product.  
         [0137]    Secondly, the pre-cure stops flow movement of uncured plastisol within the end caps, ensuring good end seals around the filter element. This increases efficiency and reduces scrap.  
         [0138]    Third, the short duration of the pre-cure allows for increased productivity and higher filter production volumes in a given time period.  
       Horizontal-to-Vertical Rotation and Transfer Mechanism  
       [0139]    After the pre-cure is completed, the gripper assembly  30  carries the pre-cured filter cartridge assembly down to a drop-off point, where the gripper assembly is opened to drop the filter into a transfer mechanism, for transferring the filter to a cure line. Upon completion of the pre-cure, the individual gripper assembly  30  carries the filter element down to a drop-off station  100 , shown in FIG. 8, where the gripper assembly  30  is opened to drop the workpiece. This is accomplished by the transport conveyor  33  moving the gripper assembly  30  past a stationary cam  85 , which is attached to a plate  87 , as shown in phantom in FIG. 8. As the gripper assembly  30  moves past the stationary cam  85 , the stationary cam presses on the cam follower bearing  88  of the gripper assembly  30 . This pressure moves the outer cage  52  inwardly towards the base plate of the inner cage, which presses the crossmember  78  so as to compress the internal spring  48  of the assembly. At the same time, the inward pressure on the outer cage  52  moves the cam follower bearings  62 ,  63  on the hinge portions inwardly with respect to the inner cage  46 , while the pivot pin is held fixed in the inner cage. This forces the jaws  32 ,  34  open, releasing the filter cartridge  17  therefrom.  
         [0140]    When the jaws  32 ,  34  of the gripper assembly open, the filter cartridge  17  is dropped into a shuttle member  102 . The shuttle member has two opposed Y-shaped cradles  104 ,  106 , which are each pivotally attached to opposite ends of a yoke  105 . When activated by a motor or other driving means, the Y-shaped cradles  104 ,  106  pivot sideways together, in coordinated fashion, to transfer the filter cartridge  17  into a covered tray  110 . The covered tray  110  is pivotally movable through a 90-degree arc, from a horizontal orientation, shown in solid lines, to a vertical orientation thereof, shown in phantom in FIG. 15. Although the covered tray is movable in this way, for purposes of convenience, it will be initially described in the horizontal orientation thereof shown in FIG. 8, with the understanding that it may be moved from that orientation.  
         [0141]    The covered tray  110  includes a base tray portion  112 , having a substantially V-shaped cross-section, and with a slot formed in the center thereof where the sides of the base tray portion come together. The slot extends about half the length of the base tray portion  112 . A first end of the base tray portion  112  is pivotally attached to a fixed support frame  114  via a pivot connection  121 , to allow for pivotal movement of the covered tray relative to the support frame. A second end of the base member carries an integrally attached backstop  116  of the covered tray, which extends upwardly from the base tray, as shown. At the top of the backstop  116 , a cover plate  118  extends outwardly therefrom from the backstop  116  above the base tray portion  112 , to provide reinforcing support to the filter cartridge  17 , as it is rotated from a vertical orientation to a horizontal orientation thereof.  
         [0142]    An extendable piston member  120  extends between the fixed support frame  114  and the underside of the base tray portion  112 , where the piston member is attached with a pivotally movable connection. It will be understood that when the piston member  120  is extended, it forces the covered tray  110  to rotate 90 degrees around the pivoting connection  121 , to the position shown in phantom in FIG. 15. This allows the filter cartridge  17  to fall out of the covered tray, in a vertical orientation thereof, on to a conveyor belt which conveys the cartridge to a final cure oven, where the adhesive is baked to permanently fix the end caps  93 ,  94  in place on the filter element  20 .  
         [0143]    Although the present invention has been described herein with respect to a preferred embodiment thereof, the foregoing description is intended to be illustrative, and not restrictive. Those skilled in the art will realize that many modifications of the preferred embodiment could be made which would be operable. All such modifications which are within the scope of the claims are intended to be within the scope and spirit of the present invention.