Patent Publication Number: US-2006016159-A1

Title: Method and apparatus for capping bottles

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application is a divisional of copending application Ser. No. 10/123,659, filed on Apr. 15, 2002.  
      The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/284,030 filed Apr. 16, 2001. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The field of the invention relates to methods for capping bottles and bottle capping devices.  
      2. Brief Description of the Related Art  
      Blown containers or bottles are in widespread use for many purposes. Such containers are often employed to store milk, juice, water and other liquids. Neck finishes of different types are formed on blown containers to accommodate various types of closures or caps. Some containers have threaded neck portions. Application of caps to such containers is accomplished in some cases by rotating a threaded cap relative to the container. U.S. Pat. No. 5,473,855 discloses a system of this type. Some threaded caps and associated neck finishes are designed such that the caps can be applied to the bottle neck portion by downward pressure on the caps. Such caps are sometimes referred to as snap-on, screw-off caps. In order to effect a satisfactory seal, some of these caps must be rotated slightly following application. U.S. Pat. No. 5,437,140 discloses a system which applies a final tightening rotation to a push on cap. Some snap-on, screw-off caps can be simply pushed on a threaded neck portion to form a leak-proof seal without having to be rotated. U.S. Pat. No. 5,775,528 discloses such a cap and neck portion. Another type of cap is often referred to as a snap-on, snap-off cap. Such a cap is not threaded, nor is the container neck portion to which it is secured. Such caps are simply pushed on the neck portions by known capping equipment. Caps as described above are often provided with annular valve members which are intended to engage the interior portion of the neck to provide a seal. The cap must be properly secured to the neck portion for the seal to be effective.  
     SUMMARY OF THE INVENTION  
      The present invention concerns a method of applying a push-on cap to a neck portion of a container in order to provide sealing and closure. Such caps include threaded and unthreaded snap-on caps as described above. The invention also concerns an assembly for securing a cap to a neck portion of a container such as a blown container.  
      The assembly for mounting a cap to the neck finish of a container includes a support and one or more applicators for engaging the top surface of the cap. At least one applicator is provided which includes structure for resiliently exerting a pressure member against the top surface of a cap. The pressure member preferably includes a substantially spherical surface. A spring or other appropriate mechanism urges the pressure member towards the cap, and resists displacement of the pressure member away from the cap. The spring pressure may be adjustable by appropriate means. In operation, the support member is positioned over a cap, and the applicator(s) engage(s) different portions of the top surface of the cap. The cap is thereby pushed onto the neck portion of the container to reliably effect closure and sealing. The applicator(s) help ensure that the cap will be applied to the neck portion without misalignment. Sequential engagement of a plurality of applicators is preferred. An effective seal is accordingly formed using a procedure and assembly that are easily employed in automated bottling plants.  
      The method according to the invention involves the resilient and preferably sequential application of pressure to various parts of the top surface of a cap, thereby urging it downwardly over the neck finish of a blown container. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a top perspective view of a capping assembly in accordance with the invention;  
       FIG. 2  is a top plan view thereof;  
       FIG. 3  is a side elevation view thereof;  
       FIG. 4  is a sectional view thereof taken along line  4 - 4  of  FIG. 1 ;  
       FIG. 5  is a top plan view of an applicator and associated bracket;  
       FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 5 , and  
       FIG. 7  is a schematic illustration of a system for filling and capping containers. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      There is shown in the drawings and described below in detail a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as exemplary of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.  
      Referring to  FIG. 1 , an assembly  10  is provided for engaging closures or caps and pushing them onto the neck finishes of containers such as blown plastic bottles. The assembly includes a support  12  and one or more applicators  14  mounted to the support. The support is in the form of a plate which may be made from stainless steel and have a thickness of about a quarter of an inch. The applicators are mounted to a flat portion of the support. The support shown in the drawings includes an upwardly curved end portion  12 A, a flat central portion  12 B, and a flat end portion  12 C on a lower plane than the central portion, as shown in  FIG. 3 . The support is generally arcuate as shown in the top view of  FIG. 2 . Posts  13  extend through openings in the support and allow height adjustment. It will be appreciated that the configuration of the support and the positioning of the applicator(s) may be different depending on the design of the capping station in which they are used.  
      Each of the three applicators employed in the preferred embodiment of the invention is identical in construction. The number of applicators and their construction may vary for various types of equipment and caps. The three applicators are in a triangular configuration for applying pressure to three different portions of the top wall of the cap. As shown in  FIG. 4 , each applicator includes a cylindrical housing  16  that includes an internally threaded lock nut at the upper end thereof. The ends of each housing  16  are open. A coil spring  18  is positioned within each housing. A pressure member  20 , such as a ball bearing or other preferably spherical member, is positioned within each housing and partially extends through the opening at the bottom end of the housing. The support may be include openings  21  that are dimensioned to retain the ball bearing or other such pressure member, as shown in  FIG. 6 . The upper end of each opening  21  is adapted to receive an end of the housing  16 . (One of the openings in  FIG. 3 . is shown without an accompanying applicator for illustrative purposes.) A threaded stud  22  is coupled to the top end of the housing. An adjustment knob  24  is mounted to the stud. One end of the spring  18  is engageable with a spring guide  25  while the other end is engageable with the pressure member. Rotation of the stud causes it and the spring guide to move towards or away from the pressure member. The force exerted on the pressure member in the direction of the cap can accordingly be varied by an operator. (In an alternative embodiment that is not shown, the force exerted on the pressure member is preset and cannot be adjusted. An opening in the housing is preferably provided in such an embodiment to facilitate cleaning the housing interior and the spring if necessary.) Other means for resiliently urging the pressure member, such as an elastomeric insert (not shown), could be employed in place of the coil spring  18 .  
      The support may include as few as one applicator. Brackets  27  may be used to mount each applicator to the support  12 . There is no known maximum number of applicators, but more than three would be unlikely to be necessary for most bottling operations. Where more than one applicator is used, the spherical end surfaces thereof are preferably arranged such that they will engage the top surface of a cap sequentially. When three applicators are used, one is positioned to traverse the central portion of the top surface. In other words, it substantially bisects the top surface of the cap. The other two applicators are positioned over the outer edge of the path  29  of the annular valve member of the cap, as shown in  FIG. 2 .  
      In use, filled containers  126  and caps  26  are provided to a capping station. The caps are positioned upon the neck portions of the containers in a known manner. The filled containers are moved with respect to the applicators such that the caps are engaged sequentially by the applicators, causing the caps to be locked in place by complementary locking features and/or threads  133 , 114  on the containers and caps. If the cap is of the type including a lower skirt  106  connected to the cap body  115  by a tear line  107 , as disclosed in U.S. Pat. No. 5,775,528, the lugs  120  of the lower skirt are moved into position between ratchet teeth (not shown) on the collar portion  134  of the container. The annular valve members  113  of the caps will also be in sealing engagement with the neck portions. The applicator(s) interact with each cap as it is seated to promote reliability in closure and sealing. The force exerted by the spring(s) is preferably such that, in normal operation, the pressure member(s) maintain contact with the top surface of the cap as it is moved with respect to the neck finish.  
      In the embodiment shown in  FIG. 1 , containers pass under the support  12  such that one applicator  14  is the first to engage each cap. This applicator maintains contact with the top surface of each cap and preferably traverses the center portion thereof. A second applicator then engages the cap, and traverses a segment on one side of the first applicator. The third applicator is the last to engage the cap, and traverses a segment on the other side of the first applicator. The sequential application of pressure along different segments of the cap moves the cap downwardly over the neck finish in a reliable manner, and causes the valve member  113  to form a reliable seal with the container rim  128  as shown in  FIG. 4 . The valve member may include an exterior taper  111  formed on the valve body  113 . The resilient application of pressure, the spherical surfaces of the pressure members, and the ability of the pressure members to rotate enhance the performance of the assembly. The upwardly extending leading end  12 A of the support initially applies pressure to the cap without fully sealing it. The trailing end  12 C is also positioned for engaging the top surface of the cap and urge it downwardly over the neck finish if necessary.  
      The method and apparatus described above are usable with various types of caps and complementary neck portions, including threaded and unthreaded caps. It is particularly applicable to the application of plastic caps to blown plastic bottles. A system for filling and capping blown bottles is shown in  FIG. 7 . A container supply and feed  30  provides containers from either storage or a blow molding assembly (not shown). The containers are filled with liquid from a liquid supply and feed  32 . A cap supply and feed  34  provides caps to the capping assembly  10  where they are applied to the neck portions of the containers. The filled, capped containers travel beneath the support  12  in the capping assembly  10  on a conveyor assembly  36 . Prior to engagement of the caps by leading end  12 A of the support and the pressure members  20 , the caps are loosely positioned on the container neck portions. The pressure member of the centrally located applicator is preferably the first to engage the cap, and moves across the center portion of the top surface of the cap while applying downward pressure thereto. It accordingly seats the front and back portions of the valve member. The pressure member of the second applicator is the next to engage the top surface of the cap, and travels along a side portion thereof substantially parallel to the path of the first pressure member. The pressure member of the third applicator then engages the top surface of the cap and travels along another side portion thereof and parallel to the path of the first pressure member. The second and third pressure members are preferably positioned over the outer edges of the path  29  of the cap valve member  113 . While the initial engagement of each pressure member in the preferred embodiment is sequential, it will be appreciated that more than one pressure member will engage the top surface of a cap at various times. The sequential pushing of the cap over the neck portion of the container causes it to move over the retention elements of the neck finish, such as threads and/or rib(s). As the cap includes a plug or valve member for sealingly engaging the rim of the neck finish, it is important for the cap to seat properly. The applicators help ensure such seating.  
      It will be appreciated that various modifications can be made to the apparatus and method described above without departing from the spirit of the invention.