Abstract:
A capping device fits caps onto containers by applying an axial force to the caps as they are threaded onto the containers. The capping device utilizes a drive member rotatable about an operational axis for imparting rotation to a capper body slidably coupled to the drive member. A helical spring urges the capper body away from the drive member with a biasing force. A bearing mechanism allows relative free sliding movement of the capper body relative to the drive member. The bearing mechanism includes a plurality of bearing members. In one embodiment, the bearing members are bushings. In another embodiment, the bearing members are ball bearings.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 11/538,722, filed Oct. 4, 2006, now U.S. Pat. No. 7,331,157, which claims the benefit of U.S. Provisional Patent Application No. 60/723,390, filed on Oct 4, 2005, the advantages and disclosure of both applications are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to a capping device for fitting pre-threaded caps onto containers, particularly beverage containers. More specifically, the present invention relates to the capping device having a bearing mechanism for allowing relatively free sliding movement between a drive member, which rotates the capping device, and a capper body, which rotates with the drive member and applies the caps onto the containers. 
     BACKGROUND OF THE INVENTION 
     Capping machines typically utilize multiple capping devices, also known as capping heads or headsets, for fitting pre-threaded caps onto containers to secure contents disposed inside the containers. A typical capping device includes a drive member operatively coupled to a drive source such as a drive motor or turret assembly. The drive source imparts rotation to the drive member. A capper body rotates with the drive member and slides relative to the drive member. A cap-engaging portion mounts to a bottom of the capper body via a torque dependent clutch such that when the capping device moves downwardly to engage a cap to thread onto a container, the clutch limits the amount of torque transmitted to the cap. 
     A spring acts between the capper body and the drive member to “soften” the impact of the capping device on the cap. In other words, the spring absorbs the impact of the downward motion of the capping device as the cap-engaging portion contacts the cap to thread the cap onto the container. Otherwise, the cap may not properly fit on the container. In some systems a biasing force provided by the spring, which slidably biases the capper body away from the drive member, is adjustable to adjust an axial force that ultimately acts on the caps. To ensure proper tuning of the biasing force, and provide consistent capping results, the capper body should slide freely relative to the drive member. Typically, the capper body includes a single shaft that slides within a bore in the drive member. Examples of such capping devices are shown in: U.S. Pat. No. 4,295,320 to Willingham; U.S. Pat. No. 4,254,603 to Obrist; and U.S. Pat. No. 6,240,678 to Spether. However, with this configuration, there is a chance that the shaft will bind up in the drive member and prevent uniform sliding movement. This could result in difficulty with processing lines and inconsistent capping results. To ensure that the capper body freely slides relative to the drive member, and to provide consistency in processing, there is a need in the art for an improved bearing mechanism disposed between the drive member and the capper body. 
     SUMMARY OF THE INVENTION AND ADVANTAGES 
     The present invention provides a capping device for fitting caps onto containers by applying an axial force to the caps as they are threaded onto the containers. The capping device includes a drive member for rotating about an operational axis. A capper body is slidably coupled to the drive member, but rotatably fixed to the drive member. A biasing member urges the capper body away from the drive member with a biasing force. A bearing mechanism is disposed between the drive member and the capper body for allowing relative sliding movement between the drive member and the capper body while preventing relative rotational movement between the drive member and the capper body. The bearing mechanism includes a plurality of bearing members secured between the drive member and the capper body for allowing free sliding movement between the drive member and the capper body. 
     By utilizing the plurality of bearing members between the drive member and the capper body, the capper body freely slides relative to the drive member without concern with significant binding against the drive member. With this configuration, the capping device has uniform sliding movement that is reproducible to provide desired capping results. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a perspective view of a capping device; 
         FIG. 2  is another perspective view of the capping device with an upper portion being spaced from a lower portion; 
         FIG. 3  is an exploded perspective view of the capping device of  FIG. 1 ; 
         FIG. 4  is a partial side view of the lower portion of the capping device; 
         FIG. 5  is a cross-sectional view of the lower portion of the capping device taken along the line  5 - 5  in  FIG. 4 ; 
         FIG. 6A  is a blown-up cross-sectional view of a retaining mechanism and adjustment mechanism of the lower portion from  FIG. 5  with the retaining mechanism shown in the latched position; 
         FIG. 6B  is a blown-up cross-sectional view of the retaining mechanism and the adjustment mechanism of the lower portion from  FIG. 5  with the retaining mechanism shown in the unlatched position; 
         FIG. 7  is a perspective view of the capping device with an alternative bearing mechanism; 
         FIG. 8  is an exploded perspective view of the capping device of  FIG. 7 ; 
         FIG. 9  is a cross-sectional view of the lower portion of the capping device of  FIG. 7 ; and 
         FIG. 10  is a perspective view of a bushing used with the capping device of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the Figures wherein like numerals indicate like or corresponding parts throughout the several views, a capping device is generally shown at  10  in  FIGS. 1 and 2 . The capping device  10  includes an upper portion  12  and a lower portion  14 . As discussed in greater detail below, the upper portion  12  mounts to a capping machine (not shown), which imparts rotation to the capping device  10  about an operational axis A via a drive motor, turret assembly, or other drive source. The lower portion  14  has a capping unit  11  (shown in phantom) mounted at a lower end thereof. The capping unit  11  may comprise a clutch  11   a  and a cap-engaging portion  11   b  such as disclosed in U.S. Pat. No. 6,240,678, hereby incorporated by reference. The rotation of the capping device  10  ultimately provides torque to the cap-engaging portion  11   b  in a conventional manner to thread pre-threaded caps C onto containers R as the containers R and the caps C pass through the capping machine. The capping device  10  simultaneously applies an axial force to the caps C and threads the caps C onto the containers R. 
     Referring to  FIGS. 1 and 2 , the lower portion  14  of the capping device  10  is removable from the upper portion  12  for servicing and/or for changing the type of capping unit  11  for different applications. The lower portion  14  of the capping device  10  shall be described in detail below. A detailed description of the upper portion  12  and the manner in which the lower portion  14  quickly connects and disconnects from the upper portion  12  is described and claimed in copending U.S. application Ser. No. 11/538,715, filed on Oct. 4, 2006, now U.S. Pat. No. 7,331,157, hereby incorporated by reference. 
     Referring to  FIGS. 2 and 3 , the lower portion  14  of the capping device  10  includes a connector  16  for inserting into the upper portion  12  to connect the lower portion  14  to the upper portion  12 . The connector  16  has a base flange  18  defining a plurality of openings  20  and a pair of channels  24 . Drive keys  25 , which are fixed to the upper portion  12 , fit snugly within the channels  24  when the lower portion  14  is connected to the upper portion  12 . The drive keys  25  transfer rotation from the upper portion  12  to the lower portion  14 . A tapered body  28  is disposed on the base flange  18  and extends upwardly from the base flange  18  for engaging the upper portion  12 , as further described in the copending application hereby incorporated by reference. 
     Referring to  FIGS. 3-5 , a drive member  32  having a cylindrical shape mounts to the connector  16 . In the embodiment shown in  FIGS. 3-5 , the drive member  32  is further defined as a drive sleeve  32 . The drive sleeve  32  has an upper flange  33  with a plurality of openings  35 . Fasteners  22  insert through the openings  20  in the base flange  18  and the openings  35  in the upper flange  33  to fix the drive sleeve  32  to the connector  16 . Thus, when the upper portion  12  rotates about the operational axis A and imparts rotation to the connector  16  via the drive keys  25 , the drive sleeve  32  also rotates with the connector  16 . 
     A capper body  34  is slidably coupled to the drive sleeve  32  and rotatably fixed to the drive sleeve  32  such that the capper body  34  slides relative to the drive sleeve  32  along the operational axis A during use and rotates with the drive sleeve  32  about the operational axis A during use. The capper body  34  includes a connector flange  52  for attaching the capping unit  11  (shown in phantom in  FIGS. 1 and 2 ) in a conventional manner. An inner sleeve  53  having a cylindrical shape extends upwardly from the connector flange  52  to inside the drive sleeve  32  (see  FIG. 5 ). 
     A bearing mechanism acts between the inner sleeve  53  and the drive sleeve  32  to provide the relative sliding movement and fixed rotational movement between the capper body  34  and the drive sleeve  32 . The bearing mechanism includes a plurality of inner bearing grooves  38  defined on an inner surface  36  of the drive sleeve  32 , parallel to the operational axis A. Likewise, the bearing mechanism includes a plurality of complimentary outer bearing grooves  42  defined on an outer surface  40  of the capper body  34 . The outer grooves  42  align with the inner grooves  38  parallel to the operational axis A. Both the inner  38  and outer  42  grooves are generally U-shaped. 
     The bearing mechanism further includes bearing members in the form of ball bearings  44  captured between the inner  38  and outer  42  grooves. The grooves  38 ,  42  and ball bearings  44  allow the capper body  34  to slide smoothly upwardly and downwardly along the operational axis A relative to the drive sleeve  32 . At the same time, the ball bearings  44  prevent relative rotation between the drive sleeve  32  and the capper body  34 . Thus, the drive sleeve  32  acts as a rotational drive member for rotating the capper body  34  about the operational axis A. Preferably, there are at least three sets of inner  38  and outer  42  bearing grooves with the ball bearings  44  located therebetween. In one embodiment, sixteen sets of inner  38  and outer  42  bearing grooves are employed with four ball bearings  44  falling within each set of grooves  38 ,  42 . In this embodiment, the ball bearings  44  are less than one-quarter inch in diameter. Preferably, the grooves  38 ,  42  have a depth equal to about one-half a diameter of the ball bearings  44 . 
     A retainer  43  is disposed inside the drive sleeve  32  to engage the capper body  34 . The retainer  43  includes threads  46  on an outer surface thereof configured to engage threads  48  disposed on an inner surface of the inner sleeve  53  of the capper body  34 . An upper rim  49  of the retainer  43  retains the ball bearings  44  within the bearing grooves  38 ,  42  at one end. Similarly, the drive sleeve  32  includes a lower rim  47  (see  FIG. 5 ) that retains the ball bearings  44  at an opposite end. Although not shown, the upper rim of the retainer  43  may include an opening for receiving a fastener to secure the retainer  43  to a top of the inner sleeve  53  of the capper body  34 . Referring briefly to the exploded view of  FIG. 3 , the ball bearings  44  are shown suspended in the outer bearing grooves  42 . It should be appreciated that this is for illustrative purposes only. During actual assembly, the drive sleeve  32  is first slid over the capper body  34  and the grooves  38 ,  42  are aligned. Then, with the grooves  38 ,  42  aligned, the ball bearings  44  are disposed in the corresponding pairs of grooves  38 ,  42  and captured between the lower rim  47  and the upper rim  49 . 
     A knock out guide tube  78  extends through the drive sleeve  32  and the capper body  34  in the lower portion  14 . The tube  78  is used to receive a knock-out rod (not shown) for purposes of expelling unneeded or jammed caps from the capping unit  11  as is well known to those skilled in the art and will not be described in detail. 
     A biasing member  50  is disposed between the drive sleeve  32  and the capper body  34  to urge the capper body  34  away from the drive sleeve  32  with a biasing force F (see  FIG. 5 ). The biasing member  50  is preferably a helical spring  50  disposed on the base flange  52  of the capper body  34  about an annular step  55 . A bellow spring (not shown) could replace the helical spring  50 . As shown, a spring washer  54  with a downwardly extending collar portion  57  is disposed on top of the helical spring  50  with the collar portion  57  fitting inside the helical spring  50 . The helical spring  50  provides the axial force ultimately applied by the capping unit  11  on the caps C as they thread onto the containers R. 
     Referring specifically to  FIG. 5 , an adjustment mechanism is operatively coupled to the helical spring  50  to adjust the biasing force F acting on the capper body  34  thereby adjusting the axial force applied to the caps C as they are threaded onto the containers R by the selected capping unit  11 . The adjustment mechanism includes outer threads  56  disposed on an outer surface of the drive sleeve  32 . The adjustment mechanism further includes a collar  61  having an inner surface with inner threads  58  for mating with the outer threads  56  of the drive sleeve  32 . A user rotates the collar  61  relative to the drive sleeve  32  between a plurality of adjustment positions to raise or lower the collar  61  along the drive sleeve  32 . As a result, since the helical spring  50  constantly presses the spring washer  54  against a flange  63  of the collar  61 , this movement compresses or decompresses the helical spring  50 . This adjusts the biasing force F provided by the helical spring  50 . 
     During operation, the collar  61  could vibrate or otherwise become dislodged from the desired adjustment position and begin to rotate upward to release the helical spring  50  and decrease the biasing force F. In order to prevent this from occurring, a retaining mechanism is operatively coupled to the adjustment mechanism to limit adjustment of the biasing force F. The retaining mechanism includes a pair of locking elements  67  movable between a latched position to prevent adjustment of the biasing force F and an unlatched position to allow adjustment of the biasing force F. The locking elements  67  are further defined as retaining pins  67 . The retaining mechanism further includes a series of vertical channels  74  defined in the outer surface  40  of the drive sleeve  32 , parallel to the operational axis A, for receiving the retaining pins  67  in the latched position. The vertical channels  74  operate as a plurality of discrete and spaced catches for the retaining pins  67 . 
     A gripping sleeve  66  is fixed to the retaining pins  67  to move the retaining pins  67  between the latched and the unlatched positions. More specifically, the retaining pins  67  interconnect the gripping sleeve  66  and the collar  61 . In this embodiment, each of the retaining pins  67  includes a first end fixed to the gripping sleeve  66  in a press-fit manner and a second, tapered end extending into elongated slots  72  defined in the collar  61 . The slots  72  penetrate through the inner threads  58  of the collar  61 . The tapered ends of the retaining pins  67  are shaped to align with the inner threads  58  of the collar  61  when the retaining pins  67  are in the unlatched position. More specifically, the tapered ends include a tapered section  73  matching the shape of the inner threads  58 . In one embodiment, the tapered section  73  includes a 60-degree taper to match a 60-degree taper of the inner threads  58 . 
     Referring to  FIG. 6A , the retaining pins  67  protrude through the slots  72  out of alignment with the inner threads  58  of the collar  61  in the latched position. Here, the second ends of the retaining pins  67  are disposed in one of the vertical channels  74 . Since the second ends of the retaining pins  67  do not align with the inner threads  58  in this latched position, the collar  61  cannot rotate relative to the drive sleeve  32 . In other words, the second ends of the retaining pins  67  abut the outer threads  56  of the drive sleeve  32  in either rotational direction. Thus, the retaining pins  67  cannot move out from the vertical channel  74 . This is the normal position of the retaining pins  67 . 
     Referring to  FIG. 6B , gripping sleeve  66  has been moved downwardly such that the retaining pins  67  protrude through the slots  72  in alignment with the inner threads  58  of the collar  61 . This is the unlatched position of the retaining pins  67 . Now, the second ends of the retaining pins  67  are aligned with the inner threads  58  to mate with the outer threads  56  of the drive sleeve  32 . Thus, the collar  61  can be rotated between the plurality of adjustment positions to adjust the biasing force F. 
     A plurality of biasing components  64 , further defined as compression springs  64 , are circumferentially spaced in recesses along the flange  63  of the collar  61  to bias the gripping sleeve  66  upwardly away from the flange  63  to normally place the retaining pins  67  in the latched position and prevent inadvertent adjustment of the biasing force F during use. The gripping sleeve  66 , which includes a textured outer surface  68  for grasping by a user, includes a lip  71  that extends downwardly beyond the collar  61  to conceal the compression springs  64 . 
     During use, the user pulls downwardly on the gripping sleeve  66  which pulls the retainer pins  67  to a bottom of the slots  72  in the collar  61  (see  FIG. 6B ). The tapered sections  73  of the retaining pins  67  are thereby aligned with the inner threads  58  such that the retaining pins  67  can move through the outer threads  56  to rotate the collar  61  relative to the drive sleeve  32  to compress or decompress the helical spring  50 . Once the desired adjustment position of the collar  61  is found, the user releases the gripping sleeve  66 . If the retaining pins  67  are not already aligned in one of the vertical channels  74 , further rotation of the collar  61  in either direction will automatically position the retaining pins  67  in the next available channel  74 . Once the retaining pins  67  are in a vertical channel  74 , the compression springs  64  automatically bias the gripping sleeve  66  upwardly and return the retaining pins  67  to a top of the slots  72  in the collar  61  in the latched position (see  FIG. 6A ). A height of the slots  72  in the collar  61  is equal to one-half the pitch distance of the inner threads  58 . Hence, the retaining pins  67 , which remain in the appropriate vertical channel  74 , are now aligned with a crest of the outer threads  56 , as shown in  FIG. 6A , such that further rotation of the collar  61  in either direction is prevented. 
     Referring back to  FIGS. 3 and 4 , a series of visual markings or markers  76  are disposed on the outer surface  40  of the drive sleeve  32  in at least a few, if not all, of the vertical channels  74  to indicate the amount of the biasing force F, i.e., compression force, such as in pounds, provided by the helical spring  50  so that a user can determine the change in the biasing force F that is made when the biasing force F is adjusted. 
     Preferably, each of the above-described components are formed of metal or metal alloys such as stainless steel, aluminum, and the like. Other suitable materials may also be used to form these components. 
       FIGS. 7-10  illustrate an alternative bearing mechanism. Like parts from the previously described bearing mechanism have been labeled with numerals indexed by  100 , unless otherwise indicated. In this embodiment, the drive member is further defined as a drive body  132 . The drive body  132  has a cylindrical shape and mounts to the connector  16  in the same manner as the previously described drive sleeve  32 . As with the drive sleeve  32 , the drive body  132  has an upper flange  133  with a plurality of openings  135 . Fasteners  22  insert through the openings  20  in the base flange  18  and the openings  135  in the upper flange  133  to fix the drive body  132  to the connector  16 . Thus, when the upper portion  12  rotates about the operational axis A and imparts rotation to the connector  16  via the drive keys  25 , the drive body  132  also rotates with the connector  16 . 
     An alternative capper body  134  is slidably coupled to the drive body  132  and rotatably fixed to the drive body  132  such that the alternative capper body  134  slides relative to the drive body  132  along the operational axis A during use and rotates with the drive body  132  about the operational axis A during use. The alternative capper body  134  includes a connector flange  152  for attaching the capping unit  11  (shown in phantom in  FIG. 7 ) in a conventional manner. 
     The alternative bearing mechanism acts between the alternative capper body  134  and the drive body  132  to provide the relative sliding movement and fixed rotational movement between the alternative capper body  134  and the drive body  132 . The alternative bearing mechanism includes a plurality of bearing shafts  153  fixed to the connector flange  152 . The shafts  153  are fixed by welding to the connector flange  152 , press-fit into openings in the connector flange  152 , or the like. Each of the shafts  153  has a cylindrical shape and extends upwardly from the connector flange  152 . The shafts  153  include threaded bores  169  at a first end for receiving threaded fasteners  157 , for purposes described further below. The alternative bearing mechanism further includes a plurality of bores  136  defined through the drive body  132 . 
     The alternative bearing mechanism also includes bearing members in the form of bushings  144 . Each of the bushings  144  includes a generally annular and cylindrical body  145  defining a through bore  147  sized and shaped to slidably receive the shafts  153 . Referring to  FIG. 10 , each of the bushings  144  has an elongated opening  200  that splits the body  145 . The bushings  144  are preferably formed from a plastic material such that they are flexible and capable of being compressed in diameter. The bushings  144  are preferably supplied from Igus GmbH of Germany, more preferably part no. JUI-06. Similar bushings that may be used are shown in U.S. Pat. No. 6,113,275 to Blase, hereby incorporated by reference. 
     Each of the bushings  144  includes a flange portion  149  having a larger diameter than the rest of the body  145 . The flange portion  149  is located generally halfway along the body  145  to split the body in equal upper and lower parts. The flange portion  149  is sized and shaped for being captured in an annular cavity or groove  138  defined in the bores  136 . During assembly, the bushings  144  are compressed via their elongated opening  200  to a smaller diameter than that of the bores  136  and are then allowed to open under their normal springing bias back to their original diameter with the flange portions  149  being seated and retained in the annular grooves  138 . In some embodiments, each of the bushings  144  include a plurality of spaced flange portions  149 , while in other embodiments (not shown), the flange portion is continuous about the body  145  (except at the elongated opening  200 ). 
     The bushings  144  include alternating ribs  202  and channels  204  that continue the entire length of the body  145 . With this configuration, when the shafts  153  are inserted into the bushings  144 , the shafts  153  only contact the ribs  202 . The ribs  202  define the surface that contacts the shafts  153 . The channels  204  are designed to receive any foreign particles and to allow the bushings  144  to react to expansion of the shafts  153  when the shafts  153  become heated during use. Should the shafts  153  expand, the ribs  202  compress and occupy part of the space available in the channels  204 . The shafts  153  continue to slide smoothly upwardly and downwardly along the ribs  202  in the bushings  144 . 
     By using multiple shafts  153 , relative rotation between the drive body  132  and the alternative capper body  134  is prevented. Thus, the drive body  132  acts as a rotational drive member for rotating the alternative capper body  134  about the operational axis A. Preferably, there are at least four sets of shafts  153 , bushings  144 , bores  136 , and grooves  138 . For purposes of illustration, the cross-sectional view of  FIG. 9 , even though cut along the operational axis A, illustrates one set of the shafts  153  and bushings  144  as being whole, and not sectioned. 
     A retainer plate  143  is movably seated in a cavity defined in an upper end of the drive body  132  over the bores  136 . The retainer plate  143  includes a plurality of openings for receiving the threaded fasteners  157  to secure the retainer plate  143  to the shafts  153 . The retainer plate  143  is adapted to move with the shafts  153  relative to the drive body  132 . The retainer plate  143  further defines a central opening  127  for receiving a knock-out tube guide  178 . The guide  178  has a first end  180  and a second end  182 . In this embodiment, the first end  180  is threaded. The guide  178  freely slides in the drive body  132  through a central bore  179  defined through the drive body  132 . 
     A nut  206  threads onto the first end  180  of the guide  178 . The nut  206  further secures the retainer plate  143  in position and prevents the guide  178  from falling through the central bore  179 . The guide  178  further includes an enlarged shoulder section  186  to prevent the guide  178  from passing through the connector flange  152 . The nut  206  and shoulder section  186  secure the connector flange  152  and retainer plate  143  therebetween. 
     During use, the shafts  153  slide in the through bores  147  of the bushings  144 . The bushings  144  are restrained in the grooves  138  of the drive body  132 . The retainer plate  143  slides with the shafts  153 . Likewise, the guide  178  slides through the central bore  179  during use with the connector flange  152  moving therewith. Thus, the shafts  153 , retainer plate  143 , threaded fasteners  157 , guide  178 , nut  206 , and connector flange  152  move as a single unit relative to the drive body  132  during use. 
     While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. It is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.