PATENT ABSTRACT
A material dispensing assembly ( 100 ) and method of operation is disclosed for converting a portable cartridge dispensing tool to a bag-type dispensing tool. The assembly comprises a single piece piston ( 110 ) for advancing material though a material housing ( 104 ), the single piece piston ( 110 ) includes a substantially square-shaped receptacle ( 140 ). The assembly further comprises a square shaped drive rack ( 112 ) for attaching to the piston ( 110 ) at the substantially square-shaped receptacle ( 140 ) at a connection end ( 128 ). The drive rack ( 112 ) further comprises a plurality of teeth ( 142 ) located thereon. The assembly ( 100 ) further has a support ( 127 ) with a substantially square profile for receiving and supporting the drive rack ( 112 ) during operation such that the construct of the drive rack and piston ( 110 ) are prevented from rotating during operation.

PATENT DESCRIPTION
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to currently pending U.S. Provisional Application Ser. No. 61/050,406 that was filed on May 5, 2008 and entitled MATERIAL DISPENSING ASSEMBLY. The present application claims priority the above-identified provisional patent application, which is incorporated in its entirety herein by reference for all purposes. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to a material dispensing assembly, and more particularly, a material dispensing assembly for sausage or bag-type dispensing tools. 
       BACKGROUND 
       [0003]    Dispensing tools have been available for a number of years, assisting in the application of material to a desired surface in residential, commercial, or manufacturing environments, Such materials include, for example, adhesives, lubricants, and sealants such as, silicone, urethanes, and caulk. Conventional dispensing tools frequently visualized are of the type of a handheld caulk gun  10 , as illustrated in  FIG. 1 , Cartridges  12  shown in  FIG. 2  having any number of different types of materials, including those listed above are inserted into a cartridge support sleeve  14  located on the top side of the dispensing tool  10 . A trigger  16  on the gun  10  when actuated drives a rack  18  having a plunger  20  that engages the material located in the cartridge  12  such that each actuation of the trigger, forces material to be dispensed from a nozzle  22  located at an end  24  of the cartridge. 
         [0004]    A more modern dispensing tool for applying various materials, including those materials listed above is a power dispensing gun  30 , having a battery, pneumatic, or other means for powering motor for portable use is illustrated in  FIG. 3 . The power dispensing gun  30  is also capable of using the cartridges  12  filled with dispensing material by inserting the cartridges  12  into a support sleeve  32  located on the top of the power dispensing gun  30 . A trigger  34  on the power dispensing gun  30  is actuated, driving a rack  36  having a plunger  38  that engages the material located in the cartridge  12  such that each actuation of the trigger forces material to be dispensed from a nozzle  40  located at the end  42  of the gun. Further details of the operation and configuration of a power dispensing gun is explained in U.S. patent application Ser. No. 11/918,689 entitled POWERED DISPENSING TOOL AND METHOD FOR CONTROLLING SAME that is assigned to the assignee of the present invention and is incorporated herein by reference in its entirety for all purposes. 
         [0005]    Cartridges  12  are not the only form of container for holding material used by the dispensing guns  10 ,  30 , but another known type of container is a sausage pack or bag-type container  50  shown in  FIG. 4 . The sausage pack  50  includes a first and second ends  52 ,  54 , respectively extending from a main body  56  having dispensing material therein. The sausage pack  50  is positioned in a housing tube  58  located on the guns  10 ,  30  in place of the cartridge support sleeves  14 ,  32 , respectively as illustrated in  FIGS. 5 and 7 . The sausage pack  50  once inserted into the guns has an opening  60  (shown in phantom is typically formed from removal of a containment ring or by piercing the sausage pack) toward the nozzle  22 ,  40  and the plunger  20 ,  38  squeezes the material out the nozzle when the trigger  16 ,  34  is engaged. 
         [0006]    One example of a dispensing tool having interchanging support sleeves includes U.S. patent application Ser. No. 11/973,242 filed on Oct. 5, 2007 entitled DISPENSING TOOL that is assigned to the assignee of the present invention and is incorporated herein by reference in its entirety for all purposes. The &#39;242 application illustrates a system for interchanging support sleeves from a cartridge-type dispenser to a sausage pack dispenser and vice versa as desired by the operator on a single power dispenser. 
         [0007]    Sausage packs  50  are typically more economical because of their cheaper fabrication. As a result, the sausage packs  50  are typically used more frequently in high volume commercial and manufacturing operations over conventional cartridges  12  in material dispensing guns. 
       SUMMARY 
       [0008]    One example embodiment of the present disclosure includes a material dispensing assembly for converting a portable cartridge dispensing tool to a bag-type dispensing tool. The assembly comprises a single piece piston for advancing material though a material housing. The single piece piston includes a substantially square-shaped receptacle. The assembly further comprises a square shaped drive rack for attaching to the piston at the substantially square-shaped receptacle at a connection end. The drive rack further comprises a plurality of teeth located thereon. The assembly further has a support with a substantially square profile for receiving and supporting the drive rack during operation such that the construct of the drive rack and piston are prevented from rotating during operation. 
         [0009]    Another example embodiment of the present disclosure includes a single-piece piston for advancing material in a dispensing gun. The piston comprises first and second ends, the first end having a dome profile with an annular taper extending outwardly toward the second end. The piston further comprises a circular seal lip integral with and extending about the perimeter of the piston, the circular seal lip includes a plurality of substantially equal segments located therebetween. A noncircular attachment aperture is located in the piston for attaching the piston to a dispensing gun. The noncircular attachment aperture in the piston prevents loosening and rotation of the piston during operation. 
         [0010]    A further example embodiment of the present disclosure includes a material dispensing gun assembly comprising a single piece piston for advancing material though a material housing. The single piece piston includes a substantially square-shaped receptacle for attaching the single piece piston to a dispensing gun and first and second ends. The first end includes an annular dome profile with first and second annular tapered surfaces extending outwardly toward the second end. The piston further comprises a circular seal lip integral and extending from the second annular tapered surface about the perimeter of the piston, the circular seal lip further comprises a plurality of substantially equal segments. The dispensing gun assembly also comprises a square shaped drive rack for attaching to the single-piece piston at the substantially square-shaped receptacle at a connection end and a plurality of teeth located thereon. The dispensing gun also includes a support having a substantially square profile for receiving and supporting the drive rack during operation such that the construct of the drive rack and piston are prevented from rotating during operation. 
         [0011]    A yet further example embodiment of the present disclosure includes a method of dispensing material from a material dispensing gun comprising loading a sausage bag comprising dispensing material into a tube removably attached to a dispensing gun, the tube having an exit end from which the dispensing material is dispensed during operation. The method also comprises locating the sausage bag between the exit end and a single piece piston in the tube and engaging the sausage bag with an annular dome located at a front end of the single piece piston located in the tube. The method further comprises advancing the single piece piston against the sausage bag with a rack fixedly attached to the single piece piston such that material located in the sausage bag engaged by the annular dome is dispensed from the exit end of the tube and unadvanced material not engaged by the annular dome extends over first and second tapered annular surfaces of the dome. The method also includes engaging the unadvanced material in the sausage bag with a circular seal lip integral and extending from the second annular tapered surface about the perimeter of the piston, the circular seal lip comprises a plurality of substantially equal segments located about the perimeter of the circular seal lip and advancing the unadvanced material with the plurality of substantially equal segments of the single piece piston such that the unadvanced material located in the sausage bag engaged by the plurality of segments is dispensed from the exit end of the tube. 
         [0012]    Another example embodiment of the present disclosure includes a material dispensing housing for use with bag-type dispensing material. The material dispensing housing comprises a transparent tube for supporting bag-type dispensing material, the tube is formed from high-temperature resistant polymeric material. The transparent tube allows for the visualization of the movement of dispensing material located within the housing during operation. The housing also comprises a base coating selected from one of a silicone coating and polysiloxane coating. The base coating provides superior service life and reduced friction of the bag holding the dispensing material and reduces the friction with a piston that engages the tube and the bag-type dispensing material during operation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The foregoing and other features and advantages of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, wherein like reference numerals refer to like parts throughout the drawings and in which: 
           [0014]      FIG. 1  is a side elevation view of a manual dispensing gun adapted for a cartridge-type material container; 
           [0015]      FIG. 2  is a side cross sectional elevation view of a cartridge-type material container for use in a manual or powered dispensing gun; 
           [0016]      FIG. 3  is a side elevation view of a power dispensing gun adapted for a cartridge-type material container; 
           [0017]      FIG. 4  is a side elevation view of a sausage pack material container for use in a manual or powered dispensing gun; 
           [0018]      FIG. 5  is a perspective view of a tube for housing a sausage pack material container of  FIG. 4 ; 
           [0019]      FIG. 6  is an exploded assembly view of a material dispensing assembly adapted for a power dispensing tool constructed in accordance with one embodiment of the present disclosure; 
           [0020]      FIG. 7  is a side view of a power dispensing gun adapted to support the material dispensing assembly of  FIG. 6 ; 
           [0021]      FIG. 8A  is a rear isometric view of a single piece piston constructed in accordance with one embodiment of the present disclosure; 
           [0022]      FIG. 8B  is a front isometric view of the single piece piston constructed in accordance with the example embodiment of  FIG. 8A ; 
           [0023]      FIG. 8C  is a rear elevation view of the single piece piston constructed in accordance with the example embodiment of  FIG. 8A ; 
           [0024]      FIG. 8D  is a side elevation view of the single piece piston constructed in accordance with the example embodiment of  FIG. 8A ; 
           [0025]      FIG. 8E  is a front elevation view of the single piece piston constructed in accordance with the example embodiment of  FIG. 8A ; 
           [0026]      FIG. 8F  is a cross-section elevation side view of the single piece piston constructed in accordance with the example embodiment of  FIG. 8A ; and 
           [0027]      FIG. 8G  is a magnified view of a portion of the single piece piston cross-section identified in the example embodiment of  FIG. 8G . 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    The present disclosure relates to a material dispensing assembly  100 , and more particularly, a material dispensing assembly for easily converting portable cartridge dispensing tools to sausage or bag-type dispensing tools. One example embodiment of the material dispensing assembly  100  is illustrated in  FIG. 6 . The assembly  100  can be adapted to convert a power dispensing tool from the cartridge-type dispenser illustrated in  FIG. 3  to that of a sausage type dispenser as illustrated in the example embodiment of the power dispensing tool  102  in  FIG. 7  that can be powered by battery, pneumatic means, and the like. 
         [0029]    The power dispensing assembly  100  of  FIG. 6  comprises a sausage holding tube  104  having first and second ends  106 ,  108 , respectively. A sausage pack  50  of various lengths is installed through the first end  106  and material within the sausage pack is forced out by a piston  110  that is located behind the sausage pack in the second end  108  during operation. The material that is dispensed from the sausage pack  50  could include caulk, adhesives, silicone, urethanes, and the like without departing from the spirit and scope of the claimed invention. The piston  110  is advanced by a square piston rack  112 , which forces the piston against the sausage pack  50 , forcing material to dispense from the first end  106  through a nozzle  114  that is retained to the tube  104  by a cap  116  via a threaded connection  117 . 
         [0030]    The amount and speed of the material dispensed from the sausage pack  50  by the piston  110  could be a function of the speed of the motor (internal to the gun), or the extent of travel by the piston in the tube  104 . For example, the piston  110  could “bottom-out” against an empty sausage pack  50  that is compressed against the cap  116  and nozzle  114 . The rack  112  moveably passes through components internal to the gun  102 , including a pinion gear  118  (that engages and drives the rack in both forward and reverse directions) coupled to a gear set  120  driven in both a forward and reverse direction by a motor  122 . The positioning of the gear set  120  and pinion gear  118  in combination with supports  124  internal to the gun  102 , fix the orientation of the rack  112  through its path of travel when advancing and reversing the piston.  110  in the tube  104 . The supports  124  comprise square shaped bushings, guides, or fixtures that maintain the orientation of the rack  112  to prevent rotation of the rack or piston  110  during operation. 
         [0031]    The rack  112  includes first  126  and second  128  ends. The first end  126  passes through a barrel screw  127 , spacer  130 , end cap  132 , and washer  134 . The barrel screw  127  couples the dispensing assembly  100  through the spacer  130  and end cap  132  to a mating threaded connection  133  located in a housing porting  135  of the gun  102  for engagement with the barrel screw. Attached to the first end  126  of the rack  112  is a rack handle  136  for assisting in the reloading and unloading of the sausage packs  50  from the tube  104 . The rack handle  136  is secured to a threaded aperture located in the first end  126  of rack by a screw  138 . 
         [0032]    The first and second ends  106 , and  108 , respectively have respective threaded sections  106 A and  108 A. The first threaded section  106 A co-acts with internal threads  116 A associated with cap  116  and secures the cap to the first end  106  of the tube  104 , locking the nozzle  114  between the tube and cap at the first end. The second threaded section  108 A co-acts with internal threads  132 A associated with end cap  132 . Once the end cap  132  is secured to the housing  135  of the dispensing gun  102 , as described above, the second threaded second  108 A is screwed into the end cap, thereby supporting the tube  104  to the housing. 
         [0033]    Plungers  20  used in conventional dispensing guns (see  FIG. 1 ), are commonly threaded on the end of a drive rack  18 . Tightening the plunger  20  to the rack and applying a lock-nut is a typical means of securing the plunger. As some cartridges  12  and their corresponding support sleeves are designed to be rotated, the tendency to have the plunger  20  “unscrew” from the drive rack is appreciable, especially during operations when the user is attempting to turn the cartridge  12  while there is axial pressure being applied to the drive rack. 
         [0034]    Such problems are resolved by one embodiment of the present invention. In particular, the rack  112  comprises a square configuration to be received and attached to a corresponding a square receptacle  140  in the piston  110 , as illustrated in  FIGS. 8A ,  8 C, and  8 F. The rack  112  engages the receptacle until it is in contact with an internal face  141  in the piston  110  and is secured to the piston by a fastener  143  that passes through an opening  165  into a counter-bore  167 , for seating the fastener during attachment. Such design and the corresponding square supports  124  internal to the gun  102  prevent rotation of the rack  112  and preclude any loosening of the piston  110 . 
         [0035]    The rack  112  construction in the illustrated embodiment of  FIG. 6  provides yet another advantage from the present disclosure. The square piston  110 , corresponding square receptacle  140 , and rack  112  allow the rack to be reversed such that the first end  126  can be flipped with the second end  128 . This reversible rack  112  feature is advantageous when the rack becomes worn by the pinion gear  118  along an advanced direction (see arrow A in  FIG. 6 ). At such time that the rack  112  shows signs of wear, the mirror image construction and corresponding attachments allow the rack to be flipped  180  degrees between the first and second ends  126 ,  128  while remaining in the same orientation as shown in  FIG. 6 . The pinion  118  now drives unworn teeth  142  in the advanced direction “A”. The fasteners  138 ,  143  and receiving threaded connections in the rack  112  at first and second ends  126 ,  128  are the same, allowing the piston  110  and rack handle  136  to be reversed, extending the life of the rack as discussed above. 
         [0036]    The piston  110  provides several advantages illustrated in the exemplary embodiment of  FIGS. 6 and 8 . While conventional plungers  20  are typically configured from multiple pieces, the piston  110  is a single uniform piece made from a single molding operation. This eliminates both material and assembly costs experienced in conventional plunger designs. While the piston  110  can be made from any number of suitable polymeric materials, the construct of the piston in the example embodiment is formed from Nylon 66 material. The polymeric material of the piston  110  advantageously weighs less than one ounce, while compared to conventional plungers that weigh much more and up to eight ounces. The reduction in weight in the exemplary embodiment of the single piece piston  110  reduces stress, strain, and other ergonomic issues typically experienced in wrists and arms of operators using conventional dispensing guns. 
         [0037]    The piston  110  comprises front  144  and back  146  ends as shown in  FIGS. 8B and 8D , an annular dome  148 , and circular lip portion  150 , as shown in  FIG. 8C . The construct of the annular dome  148  at the front  144  of the piston  110  is designed to extrude the maximum amount of material from the tube  104  and sausage packet  50  therein. In particular, the dome  148  comprises a first tapered annular surface  151 , raising the unadvanced material in the sausage packet  50  up over the tapered annular face to a plurality of segmented sections  152  integrated into the dome and extending from the single piece piston  110 . In the illustrated embodiment, twelve (12) segmented sections represented by  152 A- 152 L (see  FIG. 8E ) in the circular lip portion  150  capture and advance forward the remaining material in the sausage packet  50  as the piston  110  advances through the tube  104 . While twelve segmented sections  152  are shown in the illustrated embodiment of  FIG. 8 , more or less segmented sections could be used without departing from the spirit and scope of the claimed invention. 
         [0038]    The independent flexibility achieved by the segmented sections  152 A- 152 L provide a heightened ability to facilitate a solid lip seal to a tube  104  or cartridge  12  internal wall under varying roundness tolerances especially experienced in cartridge tubes. Further the specific piston  110  diameter, piston lip geometry, including thickness, taper, and edge angles provide dispensing free of “bag wrap” failures, while enabling a low “pull back” force in sausage-type applications. In addition, the piston  110  design provides a low drag force in the forward direction (see arrow A in  FIG. 6 ), enabling greater dispensing forces to be achieved. In the illustrated embodiment of  FIGS. 8A-8G , the lip thickness represented by dimension “A” in  FIG. 8G  is approximately 0.34 inches, having a front taper  162  of approximately 6 degrees represented by dimension “B”, and edge angle off a rear edge  160  of each segmented sections  152  of approximately 15 degrees represented by dimension “C”, and a back angle off a second tapered annular surface  163  on the dome  151  of approximately 92 degrees represented by dimension “D”, as illustrated in  FIGS. 8F and 8G . 
         [0039]    The twelve segmented sections  152 A- 152 L are capable under the current embodiment of  FIG. 8  of independently undulating to maintain substantially constant regulated pressure to the sausage pack  50 , preventing bag wrap failures where the bag of the sausage pack  50  would pinch between the plunger and tube in conventional plunger designs. In the exemplary embodiment of  FIGS. 8A-8G , a vent spacing  154  is provided between the  12  segmented sections  152 A- 152 L of approximately 0.030 inches represented by dimension “X” in  FIG. 8E . The overall length of the piston is approximately  1  inch represented by dimension “E” in  FIG. 8D  and the overall diameter of the piston  110  in the illustrated embodiment of  FIG. 8  is approximately 2.0 inches as illustrated in  FIG. 8E  by dimension “F”, and the segmented sections extend from the dome  151  outward at approximately 0.69 inch diameter radius from the center “O” of the piston. It should be appreciated however, that proportionally larger and smaller dimensions would be required for larger and smaller diameter tubes and are intended to be covered by the spirit and scope of the claimed invention. 
         [0040]    The vent spacings  154  in addition to providing independent pressure to the inner diameter of the tube  104  and/or sausage pack  50 , allow air to escape from the tube when the sausage pack is being inserted or removed. This allows for easier replacement and removal of sausage packs  50  during operation by the user. The piston  110  also comprises a number of voids on the back end  146 . The voids  155  improve the overall structural strength and facilitate a reduction in the weight of the piston  110 . 
         [0041]    The tube  104  in one exemplary embodiment is transparent so that the material dispensed from the sausage pack  50  can be observed and visually measured by the user. In addition, the transparent tube  104  allows the user to visually inspect the tube while performing a cleaning operation. 
         [0042]    In another example embodiment, the tube  104  is transparent (i.e. clear and chemical resistant) and made from an a high temperature annealed polycarbonate or polyamide based material  82  and lined with a based coating  84 , allowing superior service life in a demanding environment of repeated stress, thermal, and chemical attack. Examples of suitable base coatings include silicone or polysiloxane. Such construction also reduces friction with the piston  110  and sausage bag  50  and reduces the force necessary for dispensing the material from the dispensing gun  102 . The base coatings  84  can be applied to the tube  104  by direct application, such as spraying or wiping the internal portions of the tube, through a heat treatment application process, or by extruding or impregnating the base material  82  with the base coating material during the forming of the base material. 
         [0043]    What have been described above are examples of the present invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the present invention, but one of ordinary skill in the art will recognize that many further combinations and permutations of the present invention are possible. For example, while the material dispensing assembly was illustrated being adapted to a power dispensing gun, it could equally be adapted to a manual dispensing gun without departing from the spirit or scope of the claimed invention. Accordingly, the present invention is intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims.