Abstract:
A positioning device precisely positions a work piece at a workstation. Precise positioning is accomplished through the use of a tool controller, a programmed mechanism, and a minimal pneumatic circuit. Pre-programming of the tool controller results in initially locating the work piece, precisely positioning the workpiece at the workstation, and then locking-in the position of the workpiece at the workstation time-after-time. A method for operating the positioning device is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to devices for positioning a work piece at a workstation and, more particularly, to positioning devices for precisely positioning a work piece, for example, a glass or plastic sheet, at a plurality of workstations through the use of a positioning device. A method for operating such a positioning device is also disclosed. 
     Currently, under the control of a positioning device, a work piece is re-positioned at each of several workstations so that operations can be performed on the work piece. Subsequently, the work piece is moved to additional workstations where a plurality of operations is to be performed. Typically, it is desired to position the work piece within a given positioning tolerance so that the operations performed on the work piece are reasonably accurate. 
     To accomplish precise positioning of the work piece at the workstation, it is necessary that the positioning device and associated locating equipment utilize several sensors along with much wiring and much processor computational resources and activity. Recently, however, work piece positioning and locating equipment has become very precise in the positioning of a work piece, but still require the use of several sensors, and rather significant wiring and computational resources and activity. Thus, those skilled in the art continued to seek a solution to the problem of how to provide a better precision positioning device. 
     SUMMARY OF THE INVENTION 
     The present invention relates to precision positioning of a work piece at a workstation and, optionally, subsequently at a plurality of other workstations. Central to the approach taken by the present invention is pre-programming a tool controller that controls a programmed mechanism for locating, moving, and precision positioning of a work piece at a workstation. 
     The programmed mechanism comprises at least one mounting structure where an actuator, at least one fluid cylinder having a cylinder rod lock, a vacuum generator, and at least one vacuum cup are disposed. The actuator, fluid cylinder with cylinder rod lock, vacuum generator, and vacuum cup are linked together to comprise a fluid circuit. 
     As a result of pre-programming, the tool controller moves the programmed mechanism toward the initial workstation so as to locate the work piece while commanding the fluid cylinder to move to an initial position. Upon reaching the work piece, the actuator senses the work piece and causes the vacuum generator to draw a vacuum in the vacuum cup, which in turn produces attachable contact between the vacuum cup and the work piece. As so embodied in the present invention, the actuator is the only sensor that is required. 
     Next, the tool controller signals the programmed mechanism, with the attached work piece, to move to the workstation where an operation is to be performed on the work piece. Upon approaching the workstation, where at least one locating stop is disposed nearby, the tool controller commands the fluid cylinder to be depressurized, thus allowing the work piece to abut the locating stop. This results in precise positioning of the work piece at the workstation. Subsequently, the tool controller commands the cylinder rod lock, which is disposed within the fluid cylinder, to lock the fluid cylinder in the precise position for the work piece at the workstation. 
     These positioning functions result in the work piece being precisely positioned at the workstation time-after-time, for the life of that operation, at the workstation and cause that precise position to be maintained while the work piece remains at the workstation. Pre-programming of the tool controller and the precise positioning capabilities of the programmed mechanism, the locating stop, the fluid cylinder, and the rod lock require little or no wiring and minimal computational resources and activity. Further, these positioning functions may be repeated for additional workstations, as required. 
     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, when read in light of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic view of a positioning device in accordance with the present invention and an associated work piece; 
         FIG. 2  is a side view of the positioning device in accordance with the present invention; 
         FIG. 3  is a side view of the positioning device at a right angle to the view of  FIG. 2 ; and 
         FIG. 4  is a bottom view of the positioning device of FIG.  2 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIG. 1 , there is shown a positioning device  10  for performing precision positioning of a work piece  12  at a workstation  14  through the use of a tool controller  16  and a programmed mechanism  20 . 
     Examples of the work piece  12  would be an automotive window glass, a vehicle plastic lite or, possibly, a metal sheet. Examples of operations performed at the workstation  14  would be priming an automotive window glass, extruding a profile onto an automotive window glass, or possibly stamping a metal sheet. The tool controller  16  could be a programmable logic controller (PLC), a robot controller, or possibly a personal computer, as examples. Examples of a programmed mechanism  20  would be a robotic arm with associated end-of-arm tooling or conventional automated electro-mechanical tooling known in the art. 
     Prior to workstation operations being performed on the work piece  12 , the programmed mechanism  20  would be semi-automatically taken through the work piece positioning functions. This would be accomplished through the use of “joystick” simulation and/or computer simulation, while the positioning function details would be captured and, consequently, stored in the memory of the tool controller  16 . 
     The following are some of the main positioning device functions that would be performed on a work piece: (1) locating the work piece  12 , (2) making attachable contact with the work piece  12 , (3) moving the work piece  12  to the destination workstation  14 , (4) precisely positioning the work piece  12  at the workstation  14 , and (5) locking-in the precise position at the workstation  14 , so that workstation operations do not disturb the-precise positioning. The pre-programming and storage of the workstation positioning functions in the tool controller  16  would be repeated for all workstations  14 . 
     As a result, the tool controller  16  would mechanically, electrically, and/or fluidly control the positioning functions of the programmed mechanism  20  by way of a minimal fluid circuit  22 , thus requiring minimal computational resources and activity. The programmed mechanism  20  comprises an adapter  39  and at least one mounting structure  26  where an actuator  28 , at least one fluid cylinder  32  with attached cylinder rod lock  38 , a vacuum generator  34 , and at least one vacuum cup  36  would be disposed. The actuator  28 , fluid cylinder  32 , cylinder rod lock  38 , vacuum generator  34 , and the vacuum cup  36  are linked together to comprise the fluid circuit  22 . 
     The adapter  39  could be a collar that mechanically rotatably interfaces the end-of-arm tooling or conventional tooling to the mounting structure  26 . In a preferred embodiment that is illustrated in  FIGS. 2-4 , the mounting structure  26  comprises aluminum plates, and the actuator  28  is a spring-loaded plunger. The fluid cylinders  32  are preferably air cylinders. However, the fluid circuit components may be pneumatic or hydraulic in nature. 
     The basic functions of the positioning device  10  would have the programmed mechanism  20  move toward and into contact with the work piece  12  while the tool controller  16  is commanding the fluid cylinder  32  to be positioned in an initial position. An example of the initial position would be in the direction toward the initial workstation. Upon reaching the work piece  12 , the actuator  28  would be contacted and thus cause the vacuum generator  34  to draw a vacuum in the vacuum cups  36 , which in turn would produce attachable contact between the vacuum cups  36  and the work piece  12 . 
     In conjuction with  FIGS. 2-4 , the tool controller  16  would signal the programmed mechanism  20  to move the work piece  12  toward the workstation  14 , where a locating stop  24  would be disposed nearby. As the programmed mechanism  20  approaches the workstation  14 , the tool controller  16  would command the fluid cylinder  32  to depressurize, thus causing the work piece  12  to be precisely positioned at the workstation  14 , which would be relative to and abutting the locating stop  24 . Subsequently, the programmed mechanism  20  would command the rod lock  38 , which would be disposed within the fluid cylinder  32 , to lock the fluid cylinder  32  in the precise position for the work piece  12 , at the workstation  14 . 
     Pre-programming of: (1) precise workstation  14  and locating stop  24  locations, (2) precision control of the fluid cylinder  32 , and (3) locking-in of the rod lock  38 , result in precisely positioning the work piece  12  at the workstation  14 . This precision positioning is accomplished while using the actuator  28  as the only sensor. In addition, the pre-programming, as so described, results in minimal computational resources and activity. 
     In accordance with the provisions of the patent statutes, the principles and modes of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood that the invention may be practiced otherwise than specifically explained and illustrated without departing from its spirit or scope.