Abstract:
A capping chuck for a bottle capping machine is capable of applying a pre-defined torque to a cap and reducing top load during application. The capping chuck includes a drive gear mechanically connected to a clutch. The clutch controls the torque transmitted to a gripper head through a driveshaft. The gripper head secures the cap to the bottle, and includes a substantially continuous perimeter wall surrounding a plunger that moves under load in a direction parallel to the longitudinal axis of the driveshaft. The extent of movement can be controlled by a resistance element such as, for example, a spring. An engagement device affects the contact the drive gear has with the bull gear of the capping mechanism. The engagement device can rotate the capping chuck relative to the bull gear to ensure positive engagement of the drive gear with the bull gear. The engagement device can include a slotted opening and an adjustment screw.

Description:
The present invention claims priority to U.S. 61/105,153, which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a chuck, particularly a capping chuck for use in applying a cap to a bottle. 
     BACKGROUND OF THE INVENTION 
     Filling and capping processes typically include conveying bottles to a filling station and capping them at a capping station. The processes can also include various testing and control functions such as, for example, testing and control of fill volume, cap torque, conveyor velocity, etc. 
     The capping station comprises a capping mechanism. The capping mechanism can include torque sensors and convertors, various cap head designs, rotary screw heads, conveying apparatus, and various capping chucks for holding the caps. Capping chucks secure the caps to the bottles. Capping chucks can include a clutch that limits the torque applied to the cap. The clutch can include a magnetic engagement that may be adjusted for various torque requirements. 
     Various applications require frequent cleaning of the capping mechanism. In these applications, a reduction in surface area or mechanical junctions can facilitate cleaning and reduce downtime. 
     SUMMARY OF THE INVENTION 
     The present invention describes a capping chuck for a bottle capping machine. The capping chuck is capable of applying a pre-defined torque to a cap with reduced top load during application. The capping chuck includes a drive gear mechanically connected to a clutch which drives a jaw. The gripper head secures the cap to the bottle. 
     In one embodiment, the drive gear is mechanically connected to the clutch. A driveshaft connects the clutch to the jaw. A shield can protect the driveshaft. Preferably, the shield is perforated. 
     The gripper head includes a perimeter wall surrounding a base. The perimeter wall can be serrated to improve contact with the cap. The perimeter wall can also be tapered toward the base. Under load, the plunger can move in a direction parallel to the longitudinal axis of the driveshaft. The extent of movement can be controlled by a resistance element such as, for example, a spring. 
     The clutch is preferably separated from the gripper head by the driveshaft. The clutch can control the amount of torque at the jaw. The clutch can include friction or magnetic elements, and preferably can be adjusted. In an embodiment, the clutch includes at least two magnetic arrays that are disposed in opposite polarity. The magnetic array can include a plurality of magnetic elements. The mutual magnetic repulsion of the magnetic arrays controls the amount of torque at the jaw. When the torque exceeds the mutual magnetic repulsion, the clutch slips. 
     The drive gear can engage a bull gear on the capping mechanism. The bull gear is capable of driving a plurality of drive gears. The capping chuck can include an engagement device that ensures good contact of the drive gear with the bull gear. The engagement device can rotate the capping chuck relative to the bull gear to ensure positive engagement of the drive gear with the bull gear. The engagement device can include a slotted opening and an adjustment screw. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a first capping chuck of the prior art. 
         FIG. 2  shows the gripper head of  FIG. 1 . 
         FIG. 3  shows the gripper head of  FIG. 1  along a longitudinal axis. 
         FIG. 4  shows a second capping chuck of the prior art. 
         FIG. 5  shows the gripper head and the clutch of  FIG. 4 . 
         FIG. 6  is an exploded view of the clutch of  FIG. 4 . 
         FIG. 7  shows the capping chuck of  FIG. 4  without the protective cover. 
         FIG. 8  shows an embodiment of the capping chuck of the present invention. 
         FIG. 9  shows a rear view of  FIG. 8 . 
         FIG. 10  shows the gripper head of  FIG. 8  along a longitudinal axis. 
         FIG. 11  shows the clutch and driving gear of  FIG. 8 . 
         FIG. 12  shows a perspective view of the driving gear and an engagement device. 
         FIG. 13  shows the capping chuck of the present invention on a capping mechanism. 
         FIG. 14  shows a cross-section of an embodiment of a clutch of the present invention. 
         FIG. 15  is a cross-section of  FIG. 14  through A-A. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIGS. 1-3 , a capping chuck  1  can include a driveshaft  2  that mechanically connects a drive gear  3  to a gripper head  4 . The drive gear  3  engages a bull gear (not shown) of a capping mechanism. In a multi-stage capping mechanism, the bull gear can drive a plurality of capping chucks. The bull gear rotates the drive gear  3  and the drive shaft  2  transfers the rotation to the gripper head  4 . In embodiments, the gripper head  4  is secured to the driveshaft  2  with a retention pin  5 . Removal of the retention pin  5  permits removal of the gripper head  4  from the driveshaft  2 . 
     The gripper head  4  can include a plunger  6  surrounded by a perimeter wall  7 . The perimeter wall  7  is discontinuous and consists of a plurality of gripper jaws  8 . The gripper jaws  8  typically consist of arc sections in combination forming a discontinuous perimeter. The plunger  6  and gripper jaws  8  are normally in an expanded position. Pressure on the plunger  6  causes the gripper jaws  8  to move inwardly. In practice, the capping chuck  1  is pressed down onto a cap (not shown), the gripper jaws  8  move inwardly thereby gripping the cap, and the driveshaft  2  rotates the gripper head  4  until the cap is secured to the bottle. An operator must carefully monitor the capping operation or excess torque can cause the gripper head  4  to strip the cap causing closure failure. Alternatively, excessive pressure can crush the bottle. 
       FIGS. 4-6  show another embodiment of a capping chuck.  FIG. 7  shows a reverse view of the capping chuck. The capping chuck  41  includes a driveshaft  42  connecting a drive gear  43  to a gripper head  44 . The gripper head  44  includes a clutch  51  that can limit the torque transferred from the driveshaft  42  to the gripper head  44 . In this embodiment, the clutch  51  includes a first magnetic portion  61  separated by a spacer  62  from a second magnetic portion  63 . The strength of the magnetic portions  61 ,  63  and the thickness and material of the spacer  62  control the torque limit. Typically, the spacer comprises a plastic such as, for example, unsubstituted and substituted polyolefins; although, any convenient substance can be used. While this embodiment can limit torque, it also has its problems. Liquid can infiltrate the clutch  51  and affect the torque transmitted to the gripper head  44 . For example, liquid can reduce friction so that the gripper head  44  does not impart sufficient force to the caps. Alternatively, dried residue can increase torque and strip the caps. Cleaning can be difficult because the clutch is part of the gripper head and is subject to splashing liquid. Cleaning involves disassembly of the clutch. Shields  45  have been used to reduce cleaning; however, shields can also complicate sanitation and cleaning. Rust can form in areas that are difficult to reach. Removing the rust can require removing the capping chuck from the capping mechanism. 
       FIGS. 8-12  show an embodiment of the present invention. A capping chuck  81  comprises a drive gear  82  mechanically connected to a clutch  83 . A driveshaft  84  connects the clutch  83  to a gripper head  85 . The driveshaft  84  also separates the clutch  83  from the gripper head  85 . Separating the clutch  83  and the gripper head  85  permits cleaning the gripper head  85  without disassembling the clutch  83 . In embodiments, the clutch  83  can be at least about 10 centimeters (about 3.937 inches) from the gripper head  85 . 
     The drive gear  82  and clutch  83  can be connected by an upper shaft  111 . The clutch can include any known mechanism including, for example, friction pads, magnetic elements, and combinations thereof. Conveniently, an adjustment bolt  110  can alter the torque that the clutch  83  transmits to the driveshaft  84  and gripper head  85 . The adjustment bolt  110  can operate, for example, to increase a spring tension or to separate elements of the clutch. For example, the adjustment bolt of a magnetic clutch can move apart the magnetic elements. The adjustment bolt  110  permits changing the applied torque without disassembling the clutch  83 . 
     In embodiments, a retaining pin  86  can secure the gripper head  85  to driveshaft  84 . A shield  87  can at least partially cover the driveshaft  84 . In operation, the shield can deflect liquid splatter from the driveshaft  84  and protect equipment operators from the driveshaft  84 . The shield  87  can be perforated. Perforation can facilitate cleaning. 
     The gripper head  85  includes a plunger  92  surrounded by a substantially continuous perimeter wall  91 . The perimeter wall  91  can extend to the gripper head opening. The perimeter wall  91  consists essentially of a single piece and is tapered to receive a cap (not shown). The taper diverges from the plunger  92  at an angle of at least about 1°, and preferably from about 2° to about 5°. The taper will have a first diameter at the gripper head  85  opening that is slightly larger than the cap and a second diameter at the plunger  92  that is slightly smaller than the diameter of the cap. Optionally, the second diameter can change with movement of the plunger  92 . The first diameter permits the gripper head  85  to receive the cap and the second diameter permits retention of the cap. In embodiments, the plunger  92  can undergo a displacement along the longitudinal axis  88  of the driveshaft  84  in response to a force. Movement of the plunger  92  inwardly from the gripper head  85  opening can decrease the second diameter. A resistance element (not shown) can control the plunger&#39;s ease of movement. The resistance element can be, for example, a spring or other elastic element. Advantageously, the taper reduces the compressive force required along the longitudinal axis  88  when compared to gripper heads having a jaw comprising arc sections. 
     The perimeter wall  91  and plunger  92  can preferably travel along the longitudinal axis  88  so that the gripper head  85  remains in contact with a cap as the cap is secured to a bottle. Conveniently, the length of travel can be at least about ¼ inch (about 0.635 centimeter). Prior art capping chucks require a longitudinal load to be placed on the gripper head to ensure contact with the cap. The load ensures the arc sections of the gripper jaws engage the cap during substantially the entire capping process. An excessive load could crush or otherwise distort small or thin-walled bottles, but insufficient load would not secure the cap to the bottle. The present invention requires little or no longitudinal load to engage the capping chuck to the cap. Sealing is improved and bottles can have thinner walls. 
     The capping chuck can include a clutch  83  as shown in  FIGS. 14 and 15 . The clutch  83  includes at least two opposing mating surfaces  140 . Each mating surface  140  includes a magnetic array  141   a ,  141   b . Each magnetic array  141  includes at least one magnet  142 . In embodiments, the mating surfaces  140  can define cavities  143  into which the magnets are recessed. The magnet  142  can be any suitable magnetic device including, for example, a permanent magnet, an electromagnet, or a combination thereof. In embodiments, the magnetic arrays  141  includes a plurality of magnets  142  disposed on the mating surface  140 . Magnetic clutches of the prior art separate the mating surfaces with a spacer. This is necessary because the magnets are arranged in opposite polarity, which draws the magnets on opposing mating surfaces towards one another. The spacer prevents the magnets from sticking together. Changing the thickness of the spacer will change the mutual attraction of the magnets, and so will change the torque at which the clutch will slip. The magnets must also be fixed into the cavities or they can pop out. 
     In the present invention, the magnetic arrays  141  are arranged so that the magnets  142  present the same magnetic pole towards the mating surface  140 . This ensures that the magnets  142  of a first magnetic array  141   a  repel the magnets  142  on a second magnetic array  141   b . This repulsion causes the clutch  83  to operate so long as the torque on the clutch  83  does not exceed the repulsion force of the magnetic arrays  141 . Conveniently, the magnetic arrays  141  include a plurality of magnets  142  that are disposed so that the distance  144  between magnets  142  is at least equal to the radial arc  145  of the magnets  142 . The clutch  83  can work with only one magnet  142  on each mating surface  140 ; however, additional magnets  142  will produce a smoother mechanism. Advantageously, placing the magnets  142  in polar opposition pushes the magnets  142  into the cavities  143  so magnets  142  are less prone to popping out. Further, while a spacer can be used to separate the magnets  142 , it is not necessary as the mutual repulsion of the magnets  142  can create a suitable spacing  146  between the magnetic arrays  141 . 
     As shown in  FIG. 13 , the capping chuck  81  can include a frame for securing the capping chuck  81  to a capping mechanism  130 . In embodiments, the capping mechanism  130  can operate a plurality of capping chucks  81 . With reference to  FIG. 9 , the frame can include a pair of plates  96   a ,  96   b  united by spacer rods  97 . The driveshaft  84  extends through both plates  96 . The driveshaft  9  can pass through bushings (not shown) in each plate  96  to facilitate rotation of the driveshaft  84 . 
     A typical installation of the capping chuck  81  on the capping mechanism  130  includes a connector  131  such as, for example, a pair of lag bolts on the capping mechanism  130  that secures the capping chuck  81  to the capping mechanism  130 . The frame can define at least one slot  93  and opening  94  for receiving the lag bolts. The opening  94  will define a non-circular perimeter  100  so as to define at least one non-circular opening. The opening can be substantially oval. In embodiments, the plates  96  define a pair of slots  93  and openings  94 . The paired slots  93  and openings  94  resist movement away from the longitudinal axis  88  but do permit the capping chuck  81  to rotate about the longitudinal axis  88 . Such rotation can affect the engagement of the drive gear  82  with the bull gear so that if the gears do not align the capping chuck can be rotated to attain alignment. An adjustment screw  95  that extends into the opening  94  can lock the capping chuck  81  in proper engagement. 
     Numerous modifications and variations of the present invention are possible. It is, therefore, to be understood that within the scope of the following claims, the invention may be practiced otherwise than as specifically described. While this invention has been described with respect to certain preferred embodiments, different variations, modifications, and additions to the invention will become evident to persons of ordinary skill in the art. All such modifications, variations, and additions are intended to be encompassed within the scope of this patent, which is limited only by the claims appended hereto.