Abstract:
Rotation and positioning of a rotary index table supported from a base is effected using a cam supported from a conveyor and cam follower lock, with the conveyor and cam follower lock being mounted on a carriage set for radial movement on the base inwardly and outwardly with respect to the axis of rotation of the rotary index table, and a plurality of cam followers depending from the rotary index table.

Description:
RELATED APPLICATION 
     This application is related to provisional application 60/732,383, filed 1 Nov. 2005 and claims benefit thereof. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates to a rotary table or ring, and, more particularly, to a method and apparatus utilizing such rotary table or ring for transferring and positioning manufacturing workpieces. 
     2. Description of the Problem 
     Rotary transfer machines are advantageously applied to positioning articles for machining, assembly and/or processing where multiple operations are necessary for completion. An exemplary use of rotary transfer machines is to machine close tolerances into die cast workpieces. Rotary transfer machines typically rotate and index workpieces from station to station via a rotary index table (sometimes referred to as a “Lazy Susan”) mounted in the center of the stations. A drive control, typically a geneva drive mechanism or a two face gear coupling, performs intermittent indexing and rotating of the index table to cycle the workpieces sequentially through the stations. 
     Obtaining access to multiple surfaces of an article or workpiece undergoing processing is an advantage of rotary index tables, though there have been limitations even here. The rotary index table typically has mounted thereon several clamping pallets that hold workpieces in position. The machine tools may drive a spindle radially inward into the workpiece towards the center of the table, or may work vertically above the workpiece, or may work at an angle therebetween. The clamping pallets may either be fixed relative to the rotary index table or capable of being rotated, tilted or otherwise moved relative to the rotary index table by mounting the pallets on satellite tables that are rotatable relative to the index table. By rotating the satellite table, more sides of the workpiece are exposed to allow for machining of more sides of the workpiece. It is much less desirable to move or rotate the workpiece relative to the index table once it is locked into position for a variety of reasons. One reason is that doing so decreases the tolerances between different machining operations performed at different stations because there are two different axes of rotation which allows for play between rotational axes. Another reason is that cycle time is increased which results in an inefficiency reducing the production rate of the rotary transfer machine. Yet another reason is the high cost associated with providing the satellite tables and appropriate drive and positioning means for selectively positioning each of the satellite tables. 
     Thus rotary index tables have found limited success, particularly in use of manufacturing stations or cells. One drawback to the use of such rotary index tables, is the necessity of having the processing or work stations about the outer periphery of table which causes the workstations to be directed radially inward toward the center of the table. This geometry creates problems in work stations access and visibility during tooling setup, production, and maintenance procedures. 
     Tolerance problems regarding starting, stopping, locking, and combined rotation of the table limit usefulness of the rotary table in some applications. Controllability of the rotation of the table has been previously accomplished with rotational gear type drives or expensive digital servomotors and the like. Further, precision in flatness and location of rotary table during use has, in the past, been insufficient. 
     In view of the foregoing, there is a need for a rotary table that provides improved access to the workpiece and eliminates undesirable movement introduced by conventional drive mechanisms, and introduces exact and highly stable positioning, without sacrificing the benefits of inexpensive construction and precision in rotation and flatness. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided an automated parts transfer platform, having increased modularity and access to the workpiece. Such modularity of the system reduces total part system integration time, creates simplicity of design, and eases potential future reconfiguration and reuse of the system. 
     Standardized automated process station configurations also increase the flexibility in the modular design, and can easily be tooled or retooled for a wide array of automated process operations. 
     In one form, the system platform comprises a eight, twelve, or multiple position rotatable ring element, that can advance parts or workpieces in a rotary and high precision, synchronous movement. Functioning in theory similar to a conventional rotary indexing dial, the system offers a low cost method for part and workpiece transfers. In one aspect, the system utilizes an open ring (flat torus), rather than a solid plate indexing dial (rotating disk). This creates the advantage and option of positioning tooling and automated process stations in the inner open area of the ring facing outward for substantially better access and observation of process flow and operation. Further, the system permits additional stations to be located on the outer peripheral edge, expanding the capability of the system and provides top and bottom access to the workpiece without rotation of the workpiece on the table. 
     Another advantage to assembling self contained, easy to remove stations in interior positions, is that it significantly reduces the overall machine footprint as compared to current available systems. 
     In another form, the system includes a precision programmable servo drive motor and can lock features for a smooth advance (either clockwise or CCW rotation) cycle, and high precision lock and locate mechanism. The drive system is further modular, to allow for removal and replacement in different locations on the system, along with removal for simple repairs with minimal down time, thereby eliminating major teardowns. 
     The system accepts modular automation process stations. Each such station can be individually interconnected with robust network I/O links, quick release mountings, and modular utility connections. The stations may comprise self-contained electronics, and plumbing combined in an integrated package, thereby only requiring minutes to remove from the system instead of hours. 
     The modular stations offer advantages during the design and build process as well as during end-user production runs. Modular stations attachable to the system can be built, debugged, or repaired off line. Some replacement stations could be available as drop-in replacements for part style changeovers or in the event of calibration or maintenance issues with the original station. 
     The invention also includes increased support, utilizing vertical bearing supports located at the outer ring diameter versus a center hub, which increases strength and improves levelness of the ring during operation. 
     Additional effects, features and advantages will be apparent in the written description that follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a top plan view of one embodiment of the present invention; 
         FIG. 2  is a top plan enlarged fragmentary view of the drive mechanism shown in  FIG. 1  including the edges of ring  22  and cam followers  42 ; 
         FIG. 3  is a side-elevational fragmentary view of the drive mechanism shown in  FIG. 2 ; 
         FIG. 4  is a back-elevational fragmentary view of the drive mechanism shown in  FIG. 2 ; 
         FIG. 5  is a side-elevational view of a representative bearing utilized in the present invention; 
         FIG. 6  is a front elevational view of the representative bearing shown in  FIG. 5 ; 
         FIG. 7  is a top view of the representative bearing shown in  FIG. 5 ; 
         FIG. 8  is a partial top plan view of a bearing car or carriage which moves and positions the cams of the drive mechanism; 
         FIG. 9  is a top plan view of a torus usable as an index ring in one embodiment of the invention; 
         FIG. 10  is a bottom plan view of the torus of  FIG. 13 ; 
         FIG. 11  is a front elevation of the continuous belt drive portion of the drive mechanism; and 
         FIGS. 12A-F  are schematics illustrating operation of the drive mechanism. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     By way of overview, the rotary ring dial or ring table transfer unit system  20  is useful in various processing methods and manufacturing tasks and activities that are preferably executed upon a workpiece, article, or other such part. Stated otherwise, the invention of the embodiments of the ring dial transfer and manufacturing system disclosed herein are carried out and constructed to perform on or create an article of manufacture. 
     According to one aspect of the present invention, the system  20 , as shown in a top view  FIG. 1 , includes a flat ring  22 , that upon which are located processing areas  24 , about which may be located holes  26  through ring  22 . Ring  22  may take several forms, such as a torus, ring or solid disk. These are referred to generically in the claims as rotary dials or index tables. Holes  26  permit the processing stations  30  at times to access parts or workpieces from the direction of the bottom of ring  22 . The embodiment of  FIG. 1  shows a twelve station ring with twelve processing areas  24 . Not all processing areas  24  and holes  26  are labeled in  FIG. 1 . Alternate embodiments may contain greater or fewer stations and processing areas. 
     Ring  22  may be formed monolithically, or in connectable substantially pie shaped pieces. In one form of the invention, ring  22  may be formed of aluminum or other metal that may be hard coat anodized or otherwise hardness controlled for use with rollers. A most preferred size of ring  22  is 48 inches outside diameter and 36 inch inside diameter. 
     Ring  22  is essentially floating, and rotatably secured (via ring supports  60  in a manner to be discussed hereinafter) to a base or table  32  of conventional construction which operates as a flat and level reference point for attachment of ring  22 , ring supports ring drive mechanism  40 , and processing stations  30  (at modular processing station attachment points  28 ). Ring supports  60  allow the table to be lifted for replacement, maintenance and changeover. As shown in the embodiment illustrated in  FIG. 1 , there are twelve processing station attachment points  28  located within ring  22 , and twelve located exterior to ring  22 . The processing station attachment points  28  are standardized such that they have substantially the same layout and capacity for supplying utilities to processing stations  30  that may or may not be attached. They are illustrated as being substantially radially opposed. The utilities provided may include, but are not limited to fluids, air pressure, suction pressure, fluid pressure, water, electrical service (AC and/or DC), gas service, data connectivity, or other services. 
     In the embodiment of  FIG. 1 , there is room for processing stations  30  (not shown) both to the exterior and interior of ring  22 . Ring drive mechanism  40  takes up one processing station attachment point  28  of the eight or twelve available, either exterior and interior to ring  22 . Though the ring drive mechanism is shown in an inboard location it can be moved to the outside. 
     Other embodiments of the system may have greater or lesser number of processing stations  30 . The system is surrounded preferably by a safety cabinet structure  34  with hinged doors  36  able to be closed to secure entry to system  20 . 
     The ring drive mechanism  40  of the present invention is shown in greater detail in  FIG. 2 , and the principal behind its operation is illustrated in  FIGS. 12A-F . Generally, the drive mechanism  40  acts as a cam drive, in which the mechanism grasps and temporarily connects to at least one cam follower  42  mounted on the bottom of ring  22 , then rectilinearly moves cam or cam followers  42 , thereby rotating ring  22  a precise and known amount. The main advantage of the advance/lock operation of drive mechanism  40  is the fact that in a combined motion, the advance engagement tooling is combined with the cam lock tooling to allow, in one motion, the drive to move from advancement to the lock position without ever disengaging the ring through a “freewheeling” position. 
     More particularly, ring drive mechanism  40  includes a servo-motor  44  and gear reducer or gear box  46  for driving means such as an endless belt  48  (or other means such as a roller chain, ball screw, cable, band, or others, referred to generically as a “linear translation sub-system”) to which the cam follower bearing blocks  50  attach. Belt  48  on one end engages a drive pulley  52  connected to gear box  46 , and at the other end, an idler or take up pulley  54 . 
     In one form of the invention, one or more cam follower bearing blocks  50  are attached to belt  48  (or linear actuator). During operation of the invention, cam follower bearing blocks  50  are available to: 1) capture cam follower  42 ; 2) move cam follower  42  via a rectilinear movement of bearing block  50  as it is moved via servomotor  44 , gear box  46 , drive pulley  52  and belt  48 ; and 3) locate cam follower  42  relative to a lock member  56 . Rotary ring dial system  20  is designed that once assembled ring  22  is always positively one of captured and driven or locked, such that the location and placement of ring  22  has a high degree of precision. In one form of the invention, lock member  56  includes a beveled or chamfered channel  58  into which cam follower  42  may interfit and lock.  FIGS. 8 and 9  show an enlarged view of the drive system  40  being in either a drive position or locked position, respectively. 
     The assembly of servomotor  44 , gear box  46 , pulleys  52 ,  54  and belt  48 , along with cam follower bearing blocks  50  and lock member  56  are all carried upon a bearing car or carriage  62  ( FIGS. 2 and 3 ). This bearing car/carriage is mounted upon a linear bearing  64  that may include a subplate  66  and possibly rails, supported from base table  32  on rails  65  which are oriented so that carriage  62  moves radially inwardly and outwardly on the axis of rotation “R” in the center of ring  22 . The subplate  66  has a complementary footprint that fits any one of the modular processing station attachment points  28 , such that drive unit  40  may be located about table  32  in a modular, removably lockable connection. Such modularity of use of the connection points, that is drive  40  having the same connection type and style as the processing stations  30 , permits later movement of drive  40  to a different location, if necessary, for alternate applications and uses of ring table transfer station  20 . Such similarity of drive connection (in the present case, subplate  66 ) and processing stations  30  allow greater flexibility of design and redesign than that of prior devices. 
     Relative movement of a cam follower  42  between a cam follower bearing block  50 , more particularly from within a channel  51  in cam follower bearing block  50 , to the lock channel  58  within lock member  56  is caused by movement of bearing car/carriage  62  along linear bearing  64 . To effectuate movement of bearing car/carriage  62  a double acting cylinder drive  70  is utilized that is connected between sub plate  66  and bearing  62 . Cylinder drive  70  is either pneumatically or hydraulically driven including a double solenoid valve and provides a bi-directional linear actuator for the bearing car/carriage  62 . The structure of positive capture of cam follower  42  either within cam follower bearing block  50  or lock member  56  prevents a disengagement of cam follower  42  from either block  50  or member  56  on a potential loss of fluid pressure or unknown system shutdown or problem. The structure permits the system on energization of wake up, of precisely homing or initially placing ring  22 , via a captured cam follower  42 . Extension of cylinder  70  causes bearing car/carriage  62  to slide radially outwardly as seen from ring  22 , to the right of the drawing and thereby cause cam follower  42  as it sits under ring  22 , to translate from a captured position or driving position as shown in enlarged  FIG. 12B , to a locked position as shown in  FIG. 12A . For clarity, it should be noted that cam follower  42  is not moving during the locking maneuver, it is bearing car/carriage  62  that is translating upon linear bearing  64  on rail  65  (shown in  FIG. 4 ), causing lock member  56  with channel  58  to engage and lock about cam follower  42 . Retraction of the cylinder  70  operates the system in reverse, causing lock member  56  to release cam follower  42  to cam follower bearing block  50 , for subsequent movement and ring  22  rotation. 
       FIG. 4  shows a back elevational view of the ring drive mechanism  40  at a full home position. 
     Operation and control of the servo motor  44  and cylinder drive  70  to correctly radially place and lock ring  22  is controlled by a standard programmable logic controller (PLC)  72  such as, for example only, an Allen Bradley PLC using traditional ladder logic, or more preferably, an object oriented man-machine interface program. A plurality of sensors (not shown) are used as inputs to the PLC to capture particular machine states and locations of parts, for example cylinder  70  (extension/retraction), servo motor  44 , belt  48 , safety devices such as light curtains (about ring  22 ) and even possibly the location of ring  22 . Through use of PLC  72 , it is possible to program acceleration, deceleration, and direction of ring  22  through controlled movement of belt  48 . Alternatively, the system could be run by an appropriately programmed computer, including a personal computer. 
     Floating ring  22  is oriented and located by a plurality of ring supports  60  spread out equal distantly on an interior surface of ring  22  as shown in  FIG. 1 . Ring  22  sits upon, rotates upon, and is located by ring supports  60  and in  FIG. 1  such supports are adjacent the interior diameter of ring  22 . As shown, ring supports  60  locate and fix the axis of rotation of ring  22  and its location vertically above table  32 .  FIGS. 5 through 7  shown a ring support in more detail. A typical ring support  60  having a pillar member  73  that is attachable to base table  32 , as by a fastener such as for example a bolt (not shown) that would fit into a bore  74 . 
     Pillar member  73  creates the standoff distance of ring  22  from base plate  32  permitting the placement of ring drive mechanism  40  substantially below ring  22 . Pillar member  73  includes replaceable rotary bearing members  76  connected there to by means of a fastener  78 , such as a bolt, dell ring cap or device to permit removal and replacement of the bearing members  76 . Possibly utilized are anti-friction bearings  80  as shown, for reduced friction rotation of bearing members  76 . Based on the present disclosed design, individual bearing members  76  may be replaced without ring  22  being removed from its rotary location above table  32 . Similarly, the ring design allows for rapid and simple removal of the entire ring from the system with minimal tools for repairs or change of machine setups. 
       FIG. 8  illustrates the bearing car or carriage  62  of drive mechanism  40 , which, with double acting cylinder  70 , moves and positions the cam follower bearing block  50  and cam lock  56  of the drive mechanism. Double acting cylinder  70  operates as a linear actuator to move carriage  62  radially inwardly and outwardly as indicated by double arrow “L”. Linear bearings  64  mounted on rails  65  keep the motion linear. Several portions of the mechanism are carried on carriage  62  including principally the endless belt which carries cam block  50  back and forth as indicated by arrow “K” and locking cam  56 . Elements of the mechanism which support movement of belt  48 , that is pulleys  52 ,  54 , servo motor  44  and step down gears  46  are also part of carriage  62 . 
       FIGS. 9 and 10  illustrate a torus  22  which serves as the index ring in the preferred embodiment of the invention. Fitting of a guard  90  around the ring, which remains stationary as the ring rotates is illustrated. The location of holes/apertures  26  through the torus or ring  22 , equal in number to the number of possible workstations in a particular configuration and distributed radially equally around the torus, is shown. Holes  26  make it possible to process a workpiece mounted on the ring  22  from underneath. The location of cam followers  42  on the bottom face  127  of ring  22 . Cam followers  42  are preferably cylindrical and mounted to rotate on axes parallel to the axis of rotation of torus/ring  22 . 
       FIG. 11  is a front elevation of the continuous belt  48  drive portion of the drive mechanism. Continuous drive belt  48  is a timing belt mounted on pulleys  52  and  54  for bi-directional linear movement. Drive belt  48  carries cam follower bearing block  50  from positions opposite cam lock  56  to positions displaced from the cam lock. Cam followers  42  are carried from the bottom face of torus/ring  22  and engage cam follower bearing block  50  for indexed movement of the ring. 
       FIGS. 12A-F  illustrate operation of the drive mechanism for indexed movement and positioning of torus/ring  22 . In Position A, a cam follower  42  is caught and locked in cam lock  56 . As illustrated, cam follower  42  fits tightly into channel  58  in cam lock  56 , which has the effect of positioning ring/torus  22  positively and precisely for machining operations. A cam follower bearing block  50  is shown positioned opposite cam lock  56 . To index torus  22  it must first be unlocked. In Position B carriage  62  has been repositioned in the direction indicated by the arrow “W”, resulting in cam lock  56  being pulled away from around cam follower  42  and cam block engaging the cam follower in channel  51  as illustrated. The fit between channel  51  and a cam follower  42  need not be as tight as the fit between the cam follower and channel  58 . Continuous belt  48  may now be engaged to move the cam follower  42  and thereby rotate ring/torus  22 . Both cam lock  56  and cam follower bearing block  50  are shown with channels  58 ,  51 , respectively, for engagement with cam follower  42 . Engagement sections could be provided other than the channels shown. Cam follower bearing block  50  and its channel  51  may be termed generically as a “cam”. 
     Position C illustrates transition of the ring/torus  22 . As continuous belt  48  moves, the cam follower  42  engaged at Position B moves with it in the direction indicated by arrow “P” perpendicular to direction “W”. A second cam follower  42  rotates into position proximate to cam lock  56  until continuous belt  48  reaches the end of its allowed travel, shown in Position D. From Position D the carriage  62  moves in the direction indicated by arrow “X”, disengaging one cam follower  42  from cam follower bearing block  50 , and engaging the second cam follower  42  in cam lock  56 . Next, continuous belt  48  runs in the opposite direction as previously, returning cam block  51  (its transition is shown as Position “F”) to a position proximate to cam lock  56  as shown in Position A. 
     The present invention provides a highly predictable, mechanically simple, yet highly accurate system for operating a rotary indexing table. Functioning in theory similar to a conventional rotary indexing dial, the system offers a low cost method for part and workpiece transfers. In one aspect, the system utilizes an open ring (flat torus), rather than a solid plate indexing dial (rotating disk). This creates the advantage and option of positioning tooling and automated process stations in the inner open area of the ring facing outward for substantially better access and observation of process flow and operation. Further, the system permits additional stations to be located on the outer peripheral edge, expanding the capability of the system. Another advantage to assembling self contained, easy to remove stations in an outboard orientation, is that it significantly reduces the overall machine footprint as compared to current available systems. In another form, the system includes a precision programmable servo drive motor and can lock features for a smooth advance (either clockwise or CCW rotation) cycle, and high precision lock and locate mechanism. The drive system is further modular, to allow for removal and replacement in different locations on the system, along with removal for simple repairs with minimal down time, thereby eliminating major teardowns. The system accepts modular automation process stations. Each such station can be individually interconnected with robust network I/O links, quick release mountings, and modular utility connections. The stations may comprise self-contained electronics, and plumbing combined in an integrated package, thereby only requiring minutes to remove from the system instead of hours. The modular stations offer advantages during the design and build process as well as during end-user production runs. Modular stations attachable to the system can be built, debugged, or repaired off line. Some replacement stations could be available as drop-in replacements for part style changeovers or in the event of calibration or maintenance issues with the original station. The invention also includes increased support, utilizing vertical bearing supports located at the outer ring diameter versus a center hub, which increases the levelness of the ring during operation. 
     While the invention is shown in only a few of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.