Abstract:
Method and apparatus for mating a base deck to an assembly nest are disclosed. The method incorporates use of an alignment post supported by a visco-elastic damping material and a cam controlled mechanical finger, each precluding exposure of excessive mechanical shock impacting a base deck during alignment and positioning of the base deck within an assembly nest. The method further incorporates use of a lift deck supported by a gimbal bearing mechanism. The gimbal bearing mechanism provides attitude compliance adjustment between a base deck datum surface, and a corresponding assembly nest datum surface. Attitude compliance adjustment is promoted by a gimbaling of the lift deck about a centralized spherical bearing of the gimbal bearing mechanism, which occurs subsequent to the alignment and positioning of the base deck in respective said first and second directions and during engagement of the base deck with the assembly nest.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates generally to the field of assembly tooling and more particularly, but without limitation, to an apparatus that adaptively aligns to a workpiece, such as a head disc assembly, while laterally positioning the workpiece with a positioning mechanism within a predetermined range.  
       BACKGROUND  
       [0002]     Precise positioning of components and minimization of mechanical shock can be important considerations during device assembly operations. Head/disc interface reliability, and bearing integrity for spindle motors and actuators within data storage devices pose particularly distinct assembly handling and positioning issues.  
         [0003]     Brinelled bearings, disc divots, and crazed sliders are among the types of damage that can occur during a data storage device assembly process, as a result of component mispositioning, or device mishandling. Device mishandling causing excessive mechanical shock and component mispositioning can result in an overstressing and damage of critical components, as well as causing damage to work stations or tooling within the work stations.  
         [0004]     While various approaches for mechanical shock minimization during precise component positioning have been proposed, there nevertheless remains a continued need for improvements in the art, and it is to such improvements that the present invention is generally directed.  
       SUMMARY OF THE INVENTION  
       [0005]     In accordance with preferred embodiments, an apparatus and method are provided for mitigating mechanical shock imparted on a workpiece by impact forces of an alignment member in a mechanical finger of a lift plate used for precision positioning the workpiece within an assembly nest. The method generally comprises aligning the workpiece in a first direction relative to the lift plate using an alignment post supported by a visco-elastic damping material; using the mechanical finger to position the workpiece in the second direction relative to the lift plate; and adjusting an attitude of a lift deck supporting the visco-elastic damping material using a centralized spherical bearing mechanism communicating with the lift deck. Adjusting the attitude of the workpiece brings a surface of the workpiece into compliance with a datum of an assembly nest during an engagement of the workpiece with the assembly nest.  
         [0006]     The apparatus generally comprises a lift deck supported by a centralized spherical bearing mechanism. The spherical bearing mechanism provides compliance adjustment for a surface of a workpiece relative to the lift deck during an interaction of the workpiece with the lift deck; and an alignment member attached to the lift deck, where the alignment member includes at least an alignment post supported by a visco-elastic damping material. The alignment post provides alignment of the workpiece in a first direction relative to the lift deck during the interaction of the workpiece with the lift deck.  
         [0007]     These and various other features and advantages which characterize the claimed invention will be apparent from reading the following detailed description and a review of the associated drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a top plan view of a data storage device provided in accordance with preferred embodiments of the present invention.  
         [0009]      FIG. 2  provides an elevational view of the data storage device of  FIG. 1  communicating with an assembly conveyor.  
         [0010]      FIG. 3  is an exploded perspective view of a lift plate of the present invention.  
         [0011]      FIG. 4  is a partial cut-away plan view of the data storage device of  FIG. 1  in alignment with an assembly nest of present invention.  
         [0012]      FIG. 5  is a cross-sectional view of the assembly nest of  FIG. 4 .  
         [0000]      FIG. 6  is a partial cut-away elevational view of the data storage device of  FIG. 1  supported by the lift plate of  FIG. 3  while communicating with the assembly nest of  FIG. 4 .  
         [0013]      FIG. 7  is partial cut-away elevational view of the data storage device of  FIG. 1  supported by the assembly conveyor of  FIG. 2  in relation to the lift plate of  FIG. 3  prior to interaction of the lift plate with the data storage device.  
         [0014]      FIG. 8  is a perspective view of a position of the lift plate of  FIG. 3  prior to engagement with the data storage device of  FIG. 1 .  
         [0015]      FIG. 9  is a perspective view of a position of the lift plate of  FIG. 3  during the lift process when the lift plate is maintaining the data storage device of  FIG. 1  in contact with the assembly nest of  FIG. 4 .  
         [0016]      FIG. 10  is a partial cut-away prospective view of a gamble bearing of the lift plate of  FIG. 3 .  
         [0017]      FIG. 11  is a flowchart of a process using the lift plate of  FIG. 3 . 
     
    
     DETAILED DESCRIPTION  
       [0018]     A data storage device (DSD), such as  100  shown in  FIG. 1 , provides a vehicle for discussing preferred embodiments of the present invention. In particular, a base deck  102  of the DSD  100  serves as a workpiece example for disclosure of an application for the present invention. The base deck  102  provides central support for the balance of the remaining components of the DSD  100 .  
         [0019]     A spindle motor  106  mounted within the base deck  102  rotates a number of rigid magnetic recording discs (discs)  108  in a rotational direction  109 . An actuator  110  attached to the base deck supports a corresponding number of heads  112  adjacent tracks (not shown) defined on the disc surfaces. A voice coil motor (VCM)  114  supported by the base deck  102  is used to rotate the actuator  110  and hence, moves the heads  112  radially across the discs  108 .  
         [0020]     The VCM  114  includes a moveable actuator coil  116  and a stationary magnetic circuit. The magnetic circuit includes a permanent magnet  118  supported on a magnetically permeable pole piece  120 , which is secured to the base deck  102 . A second pole piece and a second permanent magnet are normally disposed over the coil to complete the magnetic circuit, but these components have been omitted in  FIG. 1  to provide a better view of the actuator coil  116 .  
         [0021]     A top cover  104  (shown in partial cut-away) cooperates with the base deck  102  to form an environmentally controlled housing for the DSD  100 , and a printed circuit board assembly (PCBA)  122 , mounted to the underside of the base deck  102 , provides control electronics for controlling operations of the DSD  100  and interface electronics for communicating with a host.  
         [0022]      FIG. 2  shows that the base deck  102  includes a top surface  124 , a bottom surface  126 , and a mounting rail  128 . The top surface  124  is a datum surface for the base deck  102 , while the bottom surface  126  provides support for the PCBA  122  (of  FIG. 1 ). The mounting rail  128  provides a means for attaching the DSD  100  (of  FIG. 1 ) to the host.  
         [0023]     Both the bottom surface  126  and the mounting rail  128  are cast surfaces, which are not particularly useful as reference surfaces for precision positioning of the base deck  102  during assembly of the DSD  100 . However, because the top surface  124  is a datum surface for the base deck  102 , the top surface  124  is useful for referencing the base deck  102  during the DSD  100  assembly process.  
         [0024]      FIG. 2  further shows that a conveyor  130 , found useful for DSD assembly lines, includes guide rails  132 , drive wheels  134 , and idler wheels  136 . The guide rails  132  assist in maintaining the base deck  102  in course tolerance relative to the idler and drive wheels  136  and  134  respectively. The drive wheels  134  propel the base deck  102  into and out of workstations (not shown) along a DSD assembly line (not shown). The idler wheels support the base deck  102  during transport of the base deck  102  along the DSD assembly line.  
         [0025]      FIG. 3  shows a lift plate  138  embodiment of the present invention configured to interact with the base deck  102  (of  FIG. 2 ). The lift plate  138  performs a lift operation, which raises the base deck  102  off the conveyor  130  (of  FIG. 2 ) and transfers the base deck  102  into a precision placement for performance of assembly operations by a workstation of the DSD assembly line.  
         [0026]     The lift plate  138  includes a lift deck  140 , a backer plate  142 , and a pair of mechanical fingers  144  (only one shown for clarity of presentation). The lift deck  140  supports a plurality of alignment members  146  (four shown), which are secured to the lift deck  140  by mounting hardware  148 . Each alignment member  146  provides a containment cavity  150  for deposit of a visco-elastic damping material  152 . The visco-elastic damping material  152  supports alignment posts  154  and dampens an impact of the alignment posts  154  engaging the base deck  102  during the lift operation.  
         [0027]     The backer plate  142  is secured to a lift mechanism (not shown) by attachment hardware  156 . Attached to the backer plate  142  by mounting hardware  158  is a centralized spherical bearing mechanism  160 . The centralized spherical bearing mechanism  160  includes a gamble bearing  162 , and a bearing support member  164 . The bearing support member  164  provides mounting means for attachment of the lift deck  140  to the backer plate  142  through the use of attachment hardware  166 . The backer plate  142  further provides means for attaching a spherical idler  168 . The spherical idler  168  and the gamble bearing  162  supports the lift deck  140  and provides attitude adjustment for the lift deck  140  relative to the backer plate  142 .  
         [0028]     The mechanical finger  144  includes a backer block  170 , which supports a positionable push plate  172  and a cam follower  174 . The mechanical finger  144  further includes a cam  176  with a cam surface  178 . The cam  176  is secured to the backer plate  142 . During the lift process, the cam surface  178  determines and controls a rate and path of travel of the positionable push plate  172 . The cam surface  178  includes a radius transition portion  180  interposed between a first travel control portion  182  and a second travel control portion  184 .  
         [0029]     During the lift process, the slope of the first travel control portion  182  controls the speed of travel of the positionable push plate  172  during a vertical displacement of the positionable push plate  172 . The slope of the second travel control portion  184  controls an impact force imparted on the base deck  102  by the positionable push plate  172 , when engagement between the positionable push plate  172  and the base deck  102  occurs during the lift process. As the lift mechanism begins its ascent, the vertical displacement of the positionable push plate  172  occurs at a rate faster than the rate of ascent of the lift mechanism.  
         [0030]     Upon reaching a predetermined distance of travel for the lift mechanism, the cam follower  174  progresses through the radius transition portion  180  of the cam surface  178 , and enters the second travel control portion  184  of the cam surface  178 . When the cam follower  174  follows the slope of the second travel control portion  184 , the rate of travel of the positionable push plate  172  is reduced to minimize mechanical shock imparted on the base deck  102  upon contact of the positionable push plate  172  with the base deck  102 .  
         [0031]     Each alignment post  154  includes a central shaft  186  supporting a land  188 , and a positioning member  190  supported by the land  188 . During the lift process, the positioning member  190  engages the mounting rail  128  (of  FIG. 2 ) of the base deck  102 . Upon engagement with the base deck  102  the positioning member  190  positions the base deck  102  relative to the central shaft  186  prior to engagement of the mounting rail  128  by the land  188 .  
         [0032]     During the lift process, the positioning member  190  of the alignment posts  154  aligns the base deck  102  in a first direction relative to the lift deck  140 . That is, the positioning member  190  align the base deck  102  along a width of the base deck  102  relative to the lift deck  140 . During the same lift process the positionable push plate  172 , of the mechanical finger  144 , positions the base deck  102  along a length of the base deck  102  relative to the lift deck  140 , i.e., positions the base deck  102  in a second direction relative to the lift deck  140 .  
         [0033]     Because of the inability of the bottom surface  126  (of  FIG. 2 ), and the mounting rail  128  to serve as references for precision placement of the base deck  102  into a workstation, the gambling capability of the lift deck  140  acts to accommodate interaction between the top surface  124  (of  FIG. 2 ), a datum surface of the base deck  102 , and a datum surface of an assembly nest  192 , shown by  FIG. 4 . The gambling action of the lift deck  140  occurs after the alignment and positioning of the base deck  102  in the respective first and second directions. The adjustment of the datum surface of the base deck  102  to the datum surface of the assembly nest  192  commences with a first contact with the datum surface of the base deck  102 , and concludes with attainment of a maximum vertical extent of the backer plate  142  during the lift process.  
         [0034]      FIG. 4  shows the base deck  102  in aiding contact with the assembly nest  192 , while  FIG. 5  shows a cross-section “AA” of the assembly nest  192 , which reveals a datum surface  194  and the base deck confinement channel  196 . With the datum surface of the base deck  102  in substantial continuous contact with the datum surface  194  of the assembly nest  192 , and the base deck  102  confined within the base deck confinement channel  196  precision positioning of the base deck  102  within the assembly nest  192  is achieved.  
         [0035]      FIG. 6  shows the base deck  102  mated with the assembly nest  192 , and through the cut-away portion  198 , the interface between the datum surface  194  of the assembly nest  192 , and the datum surface of the base deck  102  (top surface  124  of the base deck  102 ) can be seen.  FIG. 6  also shows a final relationship between the mounting rail  128  and the alignment posts  154 .  
         [0036]      FIG. 7  shows the contact relationship between the base deck  102  and a plurality of idler wheels  136  of the conveyor  130  (of  FIG. 2 ) prior to initiation of the lift process.  FIG. 7  also shows the relationship of a pair of alignment posts  154  relative to the plurality of idler wheels  136  prior to commencement of the lift process.  
         [0037]      FIG. 8  shows the mechanical finger  144  attached to the backer plate  142  of the lift plate  138 . As shown by the position of the cam follower  174  relative to the cam surface  178 , the positionable push plate  172  is in a retracted position, which signifies the condition of the lift plate  138  prior to commencement of the lift process.  FIG. 9  shows the condition of the lift plate  138  when, as shown by  FIG. 5 , the base deck  102  is precision positioned within the assembly nest  192  (of  FIG. 4 ).  
         [0038]      FIG. 10  shows the gamble bearing  162  which includes a race  200  confining a ball  202  having a lubricant channel  204 , a seal  206 , and a mounting aperture  208 . The mounting aperture  208  provides access for the mounting hardware  158  (of  FIG. 3 ), and the race  200  provides a mounting surface for the bearing support member  164  (of  FIG. 3 ).  
         [0039]      FIG. 11  shows a workpiece precision positioning process  300  commencing at start step  302  and continuing at process step  304  with conveyance of a workpiece (such as base deck  102 ) to a lift plate (such as  138 ) using a conveyor (such as  130 ). The process continues at process step  306  with the advancement of a lift deck (such as  140 ) of the lift plate into adjacency with the workpiece. At process step  308 , the workpiece is engaged by an alignment post (such as  154 ) of an alignment member (such as  146 ), supported by the lift deck, and aligned in a first direction relative to the lift deck at process step  310 .  
         [0040]     At process step  312 , the positionable push plate (such as  172 ) of a mechanical finger (such as  144 ), is advanced to and engages the workpiece. At process step  314 , the workpiece is positioned in a second direction relative to the lift deck. With the workpiece positioned in both a first and second direction relative to the lift plate the process continues at process step  316 . At process step  316 , an attitude of the lift deck relative to a backer plate (such as  142 ) of the lift plate is adjusted through the use of a centralized spherical bearing mechanism (such as  160 ), which includes a gamble bearing (such as  162 ) and a bearing support member (such as  164 ). The attitude of the lift deck is adjusted to bring a datum surface of a top surface (such as  124 ) of the workpiece into compliance with a datum surface (such as  194 ) of an assembly nest (such as  192 ). The workpiece precise positioning process  300  concludes at end process step  318 .  
         [0041]     Use of a lift plate (such as  138 ) in conjunction with an assembly nest (such as  192 ) is illustrative of a preferred embodiment of the present invention which precludes exposure of a workpiece (such as  102 ) to excessive mechanical shock impacting the workpiece during alignment and positioning of the workpiece within the assembly nest to achieve precision positioning of the workpiece within the assembly nest.  
         [0042]     It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.