Abstract:
A method and apparatus for handling sensitive components includes a tray having an array of integral latches. A portion of each latch serves to maintain the components on their respective mounts. The method of using the tray involves displacing the latch with an end effector to enable automated removal of the component from the tray.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims the benefit of provisional application 60/681,294 filed on May 16, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     During shipping or handling of a tray loaded with sensitive components, the components undergo vibration that can result in their displacement from their mounts. Such displacement can damage the components or result in errors during automated pick up of the components. In addition, as the components move away from their mounts, the tray is abraded. Repeated abrasion leads to particle generation which contaminates the sensitive components. Consequently, a need exists for a tray that maintains delicate components in their desired position and that protects the components from damage during shipping and handling.  
       SUMMARY OF THE INVENTION  
       [0003]     The invention concerns an apparatus for handling delicate components or workpieces such as electronic components. The apparatus may be used during processing, cleaning or transport of the workpieces.  
         [0004]     A first embodiment of the invention is an apparatus for handling workpieces comprising a tray on which an array of mounts and an array of latches are attached. The latches are integrally formed with the tray. A portion of each latch is spaced apart from a portion of each workpiece. Each latch has a hook that maintains each workpiece on its respective mount.  
         [0005]     The invention also concerns a method for using the tray with an end effector during an automated assembly process. The end effector both releases the latch and removes the workpieces from the tray. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a perspective view of a preferred embodiment of the tray of the present invention.  
         [0007]      FIG. 2  is an exploded view of a portion of  FIG. 1  containing a workpiece therein.  
         [0008]      FIG. 3  is a section view of one of the latches in  FIG. 2 .  
         [0009]      FIG. 4  is a perspective view of an end effector suitable for use with the tray of  FIG. 1 .  
         [0010]      FIG. 5  is an exploded view of the cam portion of the end effector of the present invention.  
         [0011]      FIG. 6  is an enlarged view of the end effector being used to grasp different portions of a component from a tray.  
         [0012]      FIG. 7  is a schematic drawing of the tool interface attached to the end effector of  FIG. 4 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]     The invention will now be described in detail with reference to  FIGS. 1 and 2 .  FIG. 1  illustrates a tray  100  having an array of mounts  30  upon which a component or part of a component is placed.  FIG. 1  also shows optional chamfered ribs  70  on the rectangular perimeter  75  of tray  100 . On the walls opposite perimeter  75  are recesses (not shown) that receive ribs  70  from a second tray to facilitate stacking. A third tray is able to stack onto tray  100  by mating its recesses to ribs  70  on tray  100 . Ribs  70  facilitate separating a stack of trays. As without ribs  70 , the trays of the invention tend to stick together making disassembly of the stack difficult.  
         [0014]     Tray  100  has a major surface  15  upon which an array of latches  50  is integrally formed. Latches  50  are more clearly shown in  FIG. 2 . Whenever workpiece  65  moves relative to its mount, a portion of latch  50  maintains workpiece  65  in its proper position during assembly, shipping, and handling. Both the mounts  30  and latches  50  are perpendicular to the floor  23  of tray  100 . Mounts  30  may have more than one type of shape within the same tray. In  FIG. 2 , for example, certain mounts  30  have a circular shape, while others have a substantially rectangular shape.  
         [0015]      FIG. 2  also illustrates standoffs  27 A,  27 B attached to major surface  15 . Standoffs  27 A,  27 B further secure workpiece  65  during shipping and handling of the trays. In particular standoffs  27 A,  27 B and mounts  30  and  31  restrict x/y movement of the workpiece. In the embodiment shown, standoffs  27 A,  27 B flank an inner periphery of a workpiece as shown in  FIG. 2 .  
         [0016]     Workpieces are manually placed upon one or more mounts  30  of tray  100  by an operator.  FIG. 2  illustrates a voice coil  65  on one mount and a flexible circuit board  68  on another mount. In this embodiment, latch  50  is above one side of voice coil  65 . Although specific disk drive components are shown in tray  100 , other types of workpieces may also be handled by the trays of this invention. For example, tray  100  can also store read/write heads, head suspensions, micro-actuators, as well as the head gimbal assembly shown in  FIG. 2 .  
         [0017]     On the free end of latch  50  is a hook  52  that slides over one side of workpiece  65 . Hook  52  is separated from workpiece  65  by a narrow space of approximately 0.002 inches. Hook  52  preferably runs parallel to the parting line of tray  100 . Each latch is preferably above a side of a different workpiece. Latch hook  52  prevents workpiece  65  from tilting or displacement during shipping or handling. Latch  50  thereby ensures that the workpieces remain on their mounts within an area surrounding the workpiece called the “retention space”. For example, if workpiece  65  vibrates, hook  52  on latch  50  blocks to workpiece  65  from falling off its mount, thereby retaining workpiece  65  in its desired position on the mount. By providing a latch  50  and retention space, workpiece  65  is prevented from abrading tray  100 . In turn, the limited movement of the workpiece relative to its mount results in less contamination, since particle generation is virtually avoided by the reduction in tray abrasion. Any residue that may be generated can be removed through the plurality of openings  37  that penetrate floor  23 .  
         [0018]     Latch  50  can be a clip, spring, or any other similar type of resilient mechanism. A sectional view of a preferred embodiment of latch  50  is provided in  FIG. 3 . As shown in  FIG. 3 , latch  50  consists of a first loop  51  and a second loop  53 . The center-to-center distance between loop  51  and loop  53  has a distance  310  of approximately 3.80 mm. The free end of loop  51  has a hook  52  that runs parallel to the parting line of tray  100 . In a preferred embodiment, the bottom portion  55  of hook  52  is separated by a distance  320  of approximately 3.70 mm from reference plane  35 . The two loops  51 ,  53  have external radii of 1.60 mm and 1.80 mm, respectively. The thickness of the latches preferably ranges from approximately 0.60 mm to 1.20 mm. Latches having the above dimensions are effective in restraining excessive vertical movement of a workpiece.  
         [0019]     Latch  50  is generally stationary during use. However, as explained below, latch  50  can be displaced prior to removing components from tray  100 . In this case, latch  50  has a draft angle that ranges from 0.50 to 2.0 degrees, and a spring constant of between 4.0 and 5.0 lbs/inch. In a preferred embodiment latch  50  has a spring constant of approximately 4.20 lbs/inch.  
         [0020]     Workpieces are preferably removed from tray  100  using a robotic system. One such system, illustrated in  FIG. 4 , employs an end effector  40  comprising gripping arms  44 ,  46  and a cam  73 . As shown in  FIG. 4 , cam  73  is parallel to both gripping arms  44 ,  46 . End effector  40  operates to sequentially transfer each component from tray  100 .  FIG. 4  also illustrates a tool mounting station  75  upon which various tools for operating the end effector are attached.  
         [0021]     The manner in which the latch is cleared from the retention space will now be described.  FIG. 5  illustrates an enlarged view of cam  73 . Cam  73  includes a shaft  48  and a lobe  43  that are coupled to a motor (not shown). Both the shaft  48  and lobe  43  rotate to displace hook  52  away from component  65 . Lobe  43  gradually displaces hook  52  away from the retention space. Cam  73  maintains latch  50  in an extended position until the components  65  and  68  have been lifted away from tray  100 .  
         [0022]     When latch  50  is outside the retention space, gripping arms  44  and  46  are simultaneously lowered to the position shown in  FIG. 6 —just above components  65  and  68 . Both of the gripping arms  44 ,  46  operate in unison to retrieve components from tray  100 . Specifically, while gripping arm  44  grasps component  65 , gripping arm  46  captures HSA  68 . Gripping arm  46  may comprise a pneumatic cylinder that operates with air pressure sufficient to lift up parts being stored in tray  100 . In the present embodiment, pneumatic cylinder  46  picks up a head stack assembly (HSA)  68  using between about 5-10 psi of air pressure.  
         [0023]     Gripping arm  46  includes locating pins  41  within a groove on the underside of cylinder  46 . Locating pins  41  move outward along the groove (not shown) to grasp HSA  68  via the workpiece openings  33 . The pneumatic air pressure exiting cylinder  46  enables the cylinder  46  to effectively retain HSA. The other gripping arm  44  is coupled to a vacuum source as indicated in the schematic of  FIG. 7 .  FIG. 6  illustrates gripping arm  44  as including a tubular stem  38  and a cup  31  that suctions component  65  with a vacuum. While cylinder  46  grips HSA  68 , gripping arm  44  grips component  65 . When a sensor detects that both  65  and  68  are adequately grasped, end effector  40  moves components  65  and  68  out of their mounts  30  and into hardware, such as a disk drive, printed circuit board or computer shell. Once components  65  and  68  are lifted above the retention space, cam  73  returns latch  50  to a nonextended position. Then end effector  40  transfers the workpieces into a disk drive, or other hardware. Subsequently, end effector  40  is indexed by a controller to return to a new position on tray  100 .  
         [0024]     An example of a suitable tool interface for end effector  40  is shown in  FIG. 7 . A robotic controller  82  is coupled to a vacuum source, a motor, and a pressure regulator. Pressure regulator  63  ensures that the pressure exiting cylinder  46  is within the desired ranged necessary to grip the components stored within tray  100 . Vacuum is supplied through a control valve and a vacuum stem  38 . Signals from both gripping arm  44  and pneumatic cylinder  46  are fed to controller  82  by the sensor. The end effector  40  may optionally be coupled to a machine vision system provided by, for example, video cameras connected to a computer processor, so that the robot  82  can recognize the location of the end effector and adjust its position. The controller thus controls the indexing and movement of end effector  40  during automated retrieval of components from tray  100 .  
         [0025]     The trays of the present invention are preferably manufactured with a standard injection molding process. Suitable molding materials for forming the tray include conductive, thermoplastic, non-conductive, and insulated plastic. In addition, the trays can be manufactured from material having electrostatic dissipating properties. The trays may also be manufactured using a thermoformed process.  
         [0026]     While the present invention has been described with specific examples, the skilled artisan will appreciate that various features of the invention may be modified without departing from the spirit and scope of the invention. It is therefore the intent that the scope of the invention is to be defined by the appended claims.