Abstract:
A device for mechanically gripping, transporting, loading and unloading cylindrical containers of various sizes for attachment to a robotic arm. The containers may be bottles including drinking water bottles. The device includes a plurality of gripping mechanisms for gripping the containers. Support pins are also provided for supporting the rotational motion of full bottles. A system for efficiently removing empty containers from racks and simultaneously loading full containers is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to the field of gripping, transporting, loading and unloading objects such as cylindrical containers for fluids, and specifically to a device that is capable of loading and unloading empty, partially filled, or completely filled, water bottles. Water bottles come in a variety of sizes. Those commonly used for drinking water include three (3), four (4) and five (5) gallon bottles. However, it is to be understood that the present invention could be used with any size container or bottle. Large water bottles, and especially those that are filled or partially filled, are difficult to pick up, hold and transport, due to their unique cylindrical shape and weight. Often, there is typically a requirement of not marring the exterior surface of each bottle during loading and unloading. Moreover, drinking water bottles are often recycled and refilled. Filled bottles are loaded into racks for storage and transport to customers. The same racks are returned to the water processing facility with empty bottles. The empty bottles must be removed from each rack before filled bottles are reloaded. 
     At the end of a water processing conveyor line, water bottles often arrive filled with specially filtered or processed water. While each cylindrical, bottle-shaped, container serves the primary purpose of confining the water or other fluid during shipping, the container may also serve the function of identifying the product through the use of trademarks or other product information applied directly on the container. On more elaborately printed water bottles, there may appear indicia advertising the product or its benefits. Three, four, and five gallon water bottles are commonly placed on top of a water cooler or water-dispensing device. These devices are often found in offices, homes and other highly visible areas. Therefore the container must be aesthetically attractive and visually appealing. Accordingly, it is of utmost importance that each container, and especially its product indicia, not be damaged or scuffed during removal from the conveyor line and loading for shipment. It is also important that the empty bottles returned for re-filling be treated with similar care. 
     In most instances the tasks of removing empty containers from the racks and loading full containers from a conveyor into the racks for storage or shipping have been carried out manually. While having some advantages, such as insuring that the containers are not damaged, manually handling containers is relatively a strenuous and tedious task. The continued lifting and moving of multiple, heavy filled containers can cause workers to strain and injure their backs. Further, depending upon the output speed and configuration of the conveyor line, many workers may be required to remove and properly load the filled containers. In an effort to reduce workforce size and injury costs, there has been a significant move toward automating this process by utilizing robots. 
     As is known in the art, industrial robots may be fitted with various grasping devices, known as “end-effectors” or “end of arm tools” (EOATs). Such devices may be utilized for the automated gripping and transporting of objects, including containers. 
     Most drinking water containers are cylindrical in shape and include a top, a neck, a cylindrical sidewall, and a bottom. Near the end of the water processing conveyor line, a cap is placed over the top and partially around the neck to seal the fluid within the container. Provided that the cap has been properly sealed to the container, the water will not leak, even if the container is partially or fully inverted. 
     Many end-effectors are commercially available for grasping various containers from a conveyor line and transporting them to another area. For example, a container may be removed from a conveyor line by one or more suction cups that temporarily adhere to the container. Alternatively, a pair of mechanical arms may apply a predetermined amount of pressure to the sidewalls of the container such that the container may be lifted and transported. It is even conceivable that a bladder could be placed around the container and then inflated to grasp the container for transport. 
     However, if a water bottle to be transported from a conveyor line to another station is relatively heavy (i.e. filled with a fluid, such as water), its unique geometrical shape combined with its weight makes it difficult to grasp. Suction cups cannot be readily attached to a heavy container having a unique geometry including cylindrical outer walls. Similarly, a number of mechanical arms applying a sufficient amount of pressure against the sidewall of the cylindrical container would most likely collapse or crush the container before the exerted force was great enough to lift and transport the filled container. Inflating and deflating a bladder is too time consuming and would not keep up with the rate at which filled containers arrive at the conveyor line end. 
     Another factor that controls the choice of device employed for removing bottle-shaped containers from a conveyor line and transferring them to a storage rack (or vice versa) is the consistency of container size. If each container coming off the conveyor line has the same physical size, the robotic end-effector can be designed specifically for that specific container size. However, if the container size varies, the end-effector must be capable of being readily adjustable to accommodate various container sizes. 
     Another factor that often dictates the means utilized for removing containers from conveyor lines and transporting them to storage racks is the amount of space available at the end of the conveyor line for this operation. Often times there is very little space allocated at the end of the conveyor line for removing containers. If a robot and robotic end-effector are to be utilized, the system must be sufficiently compact to allow for installation and operation within the allotted space available for such a device. 
     When filled water bottles are transported on a conveyor, they are typically moved in their upright position. The bottom or base of the bottle rests on the conveyor belt and the neck and bottle opening extend upwardly. However, the racks that are utilized for storage and transportation of water bottles hold the bottles in a horizontal orientation. Accordingly, the present invention must be capable of gripping each fall bottle and rotating the bottle from a generally vertical position to a generally horizontal position before inserting the bottle into the rack. 
     Accordingly, there is a need for a device that may be used for the gripping, transportation and placement of heavy and light cylindrical containers between two stations such as a conveyor line and a storage rack in an efficient manner. There is also a need for a device capable of easily gripping and rotating the cylindrical containers without damage. More specifically, there is a need for a device that is compact enough to be positionable and operationable at the end of a conveyor line. Furthermore, the device must be able to appropriately rotate the containers from their upright position to a horizontal position between the conveyor line and storage racks. 
     SUMMARY OF THE INVENTION 
     According to the present invention, the foregoing and other objects and advantages are attained by providing an apparatus which may be used in a confined environment to efficiently grasp and transport cylindrical objects of various sizes and weights between a pick-up position, such as the end of a conveyor line and a storage rack. The apparatus may also be used to grasp cylindrical objects from a storage rack and transport each object onto a pallet, into a case, or onto another conveyor line. In addition to grasping each object, the apparatus is capable of supportably rotating some objects through three hundred sixty (360) degrees of rotation and others through ninety (90) degrees of rotation in various planes. 
     A further object of the present invention is to provide an end-effector for an industrial robot, the end-effector being capable of picking up one or more cylindrical containers from a pick-up position and transporting the containers to a rack for storage or shipping. At the same time, additional cylindrical containers may be removed from the same rack and transported to the original pick-up position or another position. 
     A further object of the invention is to provide an end-effector that is capable of securely grasping each cylindrical object or container, whether empty or full, while not damaging or marring its outer surface. 
     In accordance with another aspect of the invention, the device can be utilized in a relatively confined area, as it requires a minimum amount of space around the periphery of the cylindrical container for gripping and loading or unloading the container. 
     A further advantage of the invention is to provide an end-effector for use with a robot that is easily adjustable to grip cylindrical containers of various sizes. 
     A further advantage of the invention is to provide a robotic end-effector that is capable of gripping more than one cylindrical container from a pick up position and transporting a group of containers to a separate location. The invention is similarly capable of gripping more than one cylindrical container from a rack and transporting said group to another location. 
     These and other objects and advantages are achieved in a system designed to unload empty and load filled, three, four, and five gallon water bottles into rack assemblies. Empty rack assemblies are loaded into a rack conveyor by a loading mechanism, such as a fork lift truck. The racks are next positively located for robotic loading. 
     Filled water bottles are conveyed into the robotic cell on the infeed conveyor. To avoid excessive backpressure, a stop mechanism allows only a predetermined number of bottles to enter the robotic pickup location. A product locator is advanced, around and between each bottle, creating the proper spacing to coincide with the rack being loaded. The robotic gripper assembly has also been adjusted to have the same spacing between the gripper mechanisms. When the bottles have been metered into position, and properly located, a conventional programmable logic controller (PLC) or similar device connected to the conveyor system signals the robot controller or control system for the robot that the bottles are ready for pickup. 
     Racks of empty bottles are conveyed into the robotic cell on the rack infeed conveyor. A rack is conveyed into the loading position, and positively positioned and held for robotic loading. When the rack has been positioned, the PLC signals the robot control system that a rack is ready for unloading and loading. The robot proceeds to unload empty bottles from the rack, and simultaneously, load full bottles into the rack. 
     The end-effector handles the same number of full bottles and empty bottles per robot cycle. Each gripper mechanism on the end-effector includes a plurality of fingers capable of moving between an open and a closed position around the bottleneck. The gripper mechanisms engage and grip around each bottleneck. In conjunction with each gripper mechanism, a pair of support pins is provided. The support pins run parallel with the longitudinal axis of each gripper mechanism. As the robot lifts the filled bottles from the conveyor, the robot wrist or fifth axis tilts upward, rotating the bottom of the bottle upwards. The support pins carry the weight of the filled bottle. 
     In a preferred embodiment, the invention may be described as an apparatus for gripping, transporting and loading or unloading a container capable of holding fluid, the apparatus having a pair of parallel rails spaced a predetermined distance from one another; a plurality of gripper mechanisms, each gripper mechanism being affixed to one of the rails; each gripper mechanism having a plurality of fingers, said finger having distal ends and each said finger being capable of moving from an open position to a clamped position; and each finger having a clamp plate attached to its distal end. In addition, the apparatus may include a number of support pins attached to each rail for supporting the containers, 
     In another preferred embodiment, the present invention is a robotic end-effector for an industrial robot, said robotic end-effector having a plate capable of being coupled to the robot, the plate including a pair of rails spaced laterally on said plate; a plurality of gripper mechanisms attached to each rail; each gripper mechanism having a number of fingers, said fingers capable of moving from an open position to a closed position. 
     In addition, the invention may be described as a system for gripping, transferring and loading or unloading fluid containers from a pick up position, the system comprising a supply of full containers at the pick up position; a rack, the rack filled with empty containers, a robot with an end-effector, the end-effector having a plurality of gripper mechanisms attached thereto; and an unloading station adjacent said pick up position whereby said end-effector simultaneously removes empty containers from said rack and loads full containers into said rack. 
     The present invention may also be described as a method for unloading empty containers and loading full containers into a rack, the method including the steps of removing an empty container from a group of empty containers in the rack, transferring said empty container to a drop off station, substantially simultaneously releasing said empty container while gripping a full container from a pick up station, transferring said full container to said rack, and loading said full container in said rack. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an environmental view depicting an industrial robot and arm, the end-effector of the present invention, an empty bottle conveyor, a full bottle conveyor, a rack and a rack conveyor. 
     FIG. 2 is a perspective view of the end-effector. 
     FIG. 3 is a front elevational view of the end-effector. 
     FIG. 4 is a side elevational view of the end-effector. 
     FIG. 5 a  is a perspective view of a gripper mechanism, showing the fingers in their open position. 
     FIG. 5 b  is a perspective view of a gripper mechanism, showing the fingers in their closed position. 
     FIG. 6 a  is an end view of the gripper mechanism fingers in their open position. 
     FIG. 6 b  is an end view of the gripper mechanism fingers in their clamped position. 
     FIG. 6 c  is an end view of the gripper mechanism fingers in their closed position. 
     FIG. 7 is an environmental view of the system, showing the bottom row of empty water bottles being removed from the rack. 
     FIG. 8 is an environmental view of the system, showing the simultaneous release of empty bottles on the exit conveyor and gripping of full bottles on the infeed conveyor. 
     FIG. 9 is an environmental view of the system, showing the rotation of the fifth axis of the robot arm while gripping full water bottles. 
     FIG. 10 is an environmental view of the system, showing the simultaneous release of full bottles in the rack and gripping of empty bottles in the rack. 
     FIG. 11 is an environmental view of the system, showing the insertion of full bottles into the top row of the rack. 
    
    
     DETAILED DESCRIPTION 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
     With reference to FIGS. 1 and 2, it will be observed that the present invention comprises an improved end-effector apparatus  10 , mounted on the arm  14  of a conventional multiple axis industrial robot  12  for gripping, transporting, loading and unloading cylindrical containers or water bottles  20 . In brief, the apparatus  10  includes a stanchion or wrist spacer  60 , a supporting top plate  70 , a plurality of bottle support pins  130  and a plurality of gripper mechanisms  140 . Each gripper mechanism  140  has a plurality of fingers  150  for gripping the bottleneck  24  of each bottle  20 . 
     With particular reference to FIG. 1, the operational environment of the present invention is shown with the end-effector apparatus  10  for gripping, transporting, loading and unloading containers  20  and the industrial robot  12  to which it is attached. Robot  12  is a 6-position or 6-axis industrial robot and includes a robot control system  16 . Adjacent the robot  12  and the apparatus  10  are a pair of conveyors  30  and  40 . Conveyor  30  is an infeed conveyor that delivers full water bottles  20   a  to the robotic cell. Conveyor  40  is an exit conveyor that transports empty containers  20   b  from the cell. Also present is a rack conveyor  50 . Rack conveyor  50  brings racks  52  of empty bottles  20   b  into the cell and conveys racks of filled bottles  20   a  from the cell for subsequent shipping or storage. The empty bottles  20   b  are removed from the racks  52  and full bottles  20   a  are loaded into the racks  52  in a predetermined order to minimize the number of robot  12  movements, thus maximizing system efficiency. A filled container or water bottle  20   a , having a cylindrical side wall  22 , neck  24  and top  26  is shown on infeed conveyor  40  ready to be transported to the rack  52 . Filled containers  20   a  include a bottle cap  28  placed over and sealing the top  26 . If the rack is of the two-bottle deep design (as shown in FIG.  1 ), a known bottle pushing apparatus  54 , such as the one shown in phantom, may be utilized to bias the rearward bottles to the front of the rack after the forward bottles have been removed. 
     While not shown in the figures, it is to be understood that the sizes of the containers  20  may be different. For example, drinking water is commonly contained within five (5), four (4), and three (3) gallon bottles. Further, the racks  52  into which the bottles  20  are removed and loaded can be of various sizes without departing from the present invention. In the purified water industry, common rack sizes include, but are not limited to three bottles by four bottles, three bottles by five bottles, four bottles by four bottles, and four bottles by five bottles. As mentioned above with respect to pushing device  54 , it is also common for the bottles to be positioned two bottles deep within each rack. As will be discussed in detail below, the ability to grip and unload or load containers of various sizes out of and into racks of various configurations is a benefit of the present invention  10 . 
     The present invention is shown in greater detail in the view of FIG.  2 . The robotic arm  14  is shown in phantom. Connected to the arm  14  is a stanchion or wrist spacer  60  at its proximate end  62 . The distal end  64  of the wrist spacer  60  is connected to a supporting top plate  70 . While both the proximate and distal end wrist spacer connections are shown to be achieved by utilizing a plurality of pins and fasteners, it is to be understood that any conventional way of connecting the industrial robot arm  14  to the top plate  70  could be utilized. 
     Supporting top plate  70  has an outer surface  72  and an inner surface  74 . Referring now to FIG. 2, mounted to the inner surface  74  of top plate  70  is a pair of first support rails  80  and  82 . Rail  80  is a fixed rail with respect to top plate  70 . It will be appreciated that rail  80  is fastened in a conventional manner to top plate  70  with fasteners  68  in two locations through pairs of circular openings  76  formed in the top plate. By contrast, rail  82  is a movable or adjustable rail. Again referring to FIG. 2, it will be seen that rail  82  is attached to top plate  70  through elongate openings  78  formed in top plate  70 . Accordingly, the position of movable rail  82  relative to fixed rail  80  can be easily adjusted by loosening the fasteners  68  that pass through the elongate openings  78  and then re-tightening the fasteners  68  in the desired position. The support rails  80  and  82  are preferably fabricated from aluminum, although any suitable material could be used. One or more end caps  84  may be installed on the rail ends. 
     For added structural integrity, a second pair of support rail members  90  and  92  is affixed with brackets  66  and fasteners  68  to first rail members  80  and  82  near their distal ends. Rail members  90  and  92  are attached to slots  86  formed in rail members  80  and  82 . Similar slots  96  in rail members  90  and  92  allow for the above-described adjustment of rail members  80  and  82 . Again, rails members  90  and  92  are preferably fabricated from aluminum and may include end caps  94  on their ends. 
     As best shown in FIG. 4, a plurality of full bottle gripper plates  110  is attached to fixed rail  80 . Similarly, a number of empty bottle gripper plates  100  is attached to adjustable support rail  82 . Each plate is attached using fasteners that pass through openings in the plate and into the elongate channels formed in each support rail  80  and  82 . Typically, the location of one empty bottle gripper plate  100 , attached to adjustable support rail  82 , is permanently fixed and the location of one full bottle gripper plate  110 , attached to fixed rail  80 , is also permanently fixed. The remaining gripper plates  100  and  110  are movable along the length of the elongate channel  86  to provide the required spacing for containers  20  of different sizes or storage rack centers. 
     Now referring specifically to full bottle gripper plates  110 , and as is shown in FIGS. 2 and 3, a multiple finger gripper mechanism  140  is attached to each gripper plate  110 . In our preferred embodiment, the gripper mechanisms  140  include three jaw gripper bodies with conventional pneumatic pistons (not shown). While not shown in the drawings, the pneumatic pistons are located within the housing of each gripper mechanism  140 . The gripper mechanisms operate on clean dry plant air systems. One such device is manufactured by Compact Air of Westminster, S.C. The preferred model is number ARG403. Referring to FIG. 5 a,  each gripper mechanism  140  further includes three bottle fingers  142 , three finger bottoms  144 , three finger pads  146  and three finger clamp plates  148 . The fingers  142  extend from the gripper mechanisms  140  and terminate at the finger bottoms  144 . The finger pad  146  is held in place between each finger bottom  144  and finger clamp plate  148 . The finger pads  146  are preferably fabricated from a urethane material having a durometer of  80 A. 
     The gripper fingers  142  act in unison and have three finger positions. The positions include full open (FIG. 6 a ), clamped (FIG. 6 b ), and closed (FIG. 6 c ). Only finger pads  146  contact the neck  24  of each bottle  20  thereby preventing damage to the bottleneck  24  and the bottle cap  28 . While a three finger arrangement has been disclosed as the preferred embodiment, it is to be understood that a fewer or greater number of fingers could be used without departing from the invention. 
     A gripper mechanism  140  may be attached to each gripper plate  100  or  110 . The gripper mechanisms for full bottles are similar to the gripper mechanisms for empty bottles in most aspects. The key differences include the provision of structurally enhanced fingers  142  attached to the gripper mechanisms  140  that grip full bottles. This is preferred due to the weight difference between an empty water bottle  20  and a full water bottle  20 . In addition, a pair of bottle support pins  130  and bottle support pin brackets  120  are attached to each full bottle gripper plate  110 . As shown in FIG. 4, the brackets  120  are affixed, with fasteners, to full bottle gripper plates  110 . A bottle support pin  130  is inserted into the opening formed on the opposite side of each bracket  120 . The pins  130  support the full water bottles  20  as they are moved from a substantially vertical position to substantially horizontal position as will be described in detail below. While the use of brackets  120  attached to gripper plates  110  is the preferred method of attaching the bottle support pins  130  to the end-effector  10 , it will be appreciated that other configurations could be utilized without departing from the invention to achieve the same result. 
     The opening and closing of gripper mechanism fingers  142  are controlled by the robot control system  16 . When the robot arm  14  has properly positioned the end-effector  10 , a pneumatic solenoid valve (not shown) is actuated, closing the gripper fingers  142 . Sensors (not shown) on the gripper mechanisms  140  indicate the open or closed state of the fingers  142 . 
     Referring to FIG.  1  and FIGS. 7 through 10, the present invention  10  is utilized in the following manner. Empty rack assemblies  52  are loaded into the rack conveyor  50  by a loading mechanism such as a fork lift truck (not shown). The racks  52  are next positively located within the robotic cell for robotic loading. 
     Filled water bottles  20   a  are conveyed into the robotic cell on the infeed conveyor  30 . The filled water bottles  20   a  are metered to a predetermined pickup location on the infeed conveyor  30 . To avoid excessive backpressure, a stop mechanism (not shown) allows only a predetermined number of bottles  20   a  to enter the robotic cell. The bottles  20   a  may be separated to provide for bottle spacing that is coincident with the spacing of the rack partitions and the gripper mechanisms  140 . A product locator may be advance, around and between each bottle  20   a , creating the proper spacing to coincide with the rack  52  being loaded. The robotic gripper assembly  10  has also been previously adjusted to have the same spacing between the gripper mechanisms  140 . When the filled and capped water bottles  20   a  have been metered into position, and properly located, a programmable logic controller (PLC) controlled to the conveyor system signals the robot control system  16  that the bottles  20  are ready for pickup. 
     Racks  52  of empty bottles  20   b  are conveyed into the robotic cell on the rack conveyor  50 . A rack  52  is conveyed into the loading position, and positively positioned and held for robotic loading. When the rack  52  has been positioned, the PLC signals the robot control system  16  that a rack  52  is ready for unloading and loading. The robot  12  proceeds to unload empty bottles  20   b  from the rack  52 , and simultaneously, load full bottles  20  into the rack  52 . 
     The preferred end-effector apparatus  10  is designed to handle four full bottles  20   a  and/or four empty bottles  20   b  per robot cycle. The end-effector  10  includes eight gripper mechanisms  140  and eight bottle support pins  130 . As previously described, a pair of bottle support pins  130  will support each filled bottle  20   a  gripped by each gripper  140  attached to the fixed support rail  80 . Each gripper  140  will engage and grip around the bottleneck  26 , and below the cap  28  of the bottle (if present). 
     In the preferred embodiment and after the rack assembly  52  has been conveyed into the cell, the end-effector apparatus  10  rotates 180 degrees so that the adjustable rail  90 , having the empty bottle gripper plates  100  and gripper mechanisms  140  attached thereto, is located along the bottom side of the end-effector apparatus  10 . In this position, and as shown in FIG. 7, the bottle support pins  130  will be located along the top side of the end-effector  10 . The end-effector  10  first grips and removes the bottom row of empty bottles  20   b  from the rack and transports the empty bottles  20   b  to the exit conveyor  40 . If the rack is two bottles deep, the back row of bottles is biased forward by a known bottle pushing apparatus  54  (shown in phantom in FIG. 1) and this back row is also gripped. While being transported to the exit conveyor  40 , the robot arm  12  again rotates one hundred eighty degrees so that, when the bottle support pins  130  are parallel to the ground, the bottle support pins  130  are now along the bottom side of the end-effector apparatus  10 . The empty bottles  20   b  are further transported and released onto the exit conveyor  40 . As shown in FIG. 8, while releasing the empty bottles  20   b  on the exit conveyor  40 , the end-effector  10  simultaneously grips a row of full water bottles  20   a  from the infeed conveyor  30 . 
     Now referring to FIG. 9, as the robot  12  lifts the full bottles  20   a  from the conveyor  30 , the robot wrist or fifth axis will tilt upward, rotating the bottom of the bottle upwards. The bottle support pins  130  carry the weight of each filled bottle  20   a . The full bottles  20   a  are transported to the rack  52  and inserted into to the bottle locations where the empty bottles were previously removed. With reference to FIG. 10, as the full bottles  20   a  are released in the rack, the row of empty bottles  20   b  located just above the now being released full bottles  20   a  are gripped and transported to the exit conveyor  40 . Again, if the bottle rack is of the two bottle deep design, the upper row of empty bottles  20   b  will be biased forward by the pushing device  54  and a second row of full bottles  20   a  will be inserted into the same rack openings thereby pushing the previously inserted bottles to the back of the rack. 
     This process is continued until the last set of empty bottles  20   b  is transported to the exit conveyor  40 . The end-effector apparatus  10  then grips a row of full water bottles  20   a  from the conveyor  30  and loads them into the rack  52 . As shown in FIG. 11, during this cycle no empty bottles are removed. Finally, the rack  52  is released from the rack conveyor  50 , conveyed out of the cell and a new rack  52  full of empty bottles  20   b  is conveyed into the cell. Once the new rack  52  is properly located and locked into position, the robotic cycle is repeated. 
     While a method of unloading empty bottles  20   b  from and loading full bottles  20   a  into rack assemblies  52  by rows has been described, it is to be understood that the same method and apparatus could be employed to unload and load bottles by columns. For example, in a three bottle by five bottle rack assembly  52  configuration, fewer robotic movements would be required to unload and load bottles by column as compared with unloading and loading by row. With respect to the end-effector  10 , the mounting position of each pin supporting bracket  120  (if present) and bottle support pin  130  would be relocated on the full bottle gripper plate  110 . By moving one pin  130  to the opposite corner of the gripper plate  110 , the new pin location would allow the pins  130  to similarly support each full bottle  20   a  when the end-effector  10  has been rotated approximately ninety degrees. 
     The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.