Abstract:
A jig assembly for preparing a disk drive for mounting in a computer comprises a bay arranged to receive a disk drive and a pair of side rails to be fixed to opposite edges of the disk drive. Each side rail has captive screws in register with a respective screw-threaded hole in the edge of the disk drive. Two powered screwdrivers on each side of the bay are in register with the screws and are mounted for movement towards and away from the respective side rail. When the disk drive and rails are loaded into the bay, pneumatic cylinders C1 automatically advance the screwdrivers towards the side rail to engage and rotate the screws to screw the side rails tight against the edge of the disk drive, and then retract the screwdrivers.

Description:
BACKGROUND 
   The present disclosure relates to a jig assembly for preparing a disk drive for inclusion in a computer. 
   Typically, during a hard disk drive (HDD) preparation process, side rails are attached to the edges of the HDD with 4 screws, two on each side. An example is shown in  FIG. 4 , where respective side rails  10  are attached by screws  12  to the respective side edges  14  of an HDD  16 . Conventionally this is done manually using a hand-held power screwdriver. This is a time consuming process which induces shock (head slap). 
   SUMMARY 
   The object of the disclosure is to provide a jig assembly which is capable of reducing the HDD preparation process time and reducing measurable shock. 
   Accordingly, the present disclosure provides a jig assembly for preparing a disk drive for mounting in a computer. 
   A disk drive receiving bay is arranged to receive a disk drive in a first datum position and to receive a pair of side rails each in a second datum position. 
   At least one powered screwdriver is provided on each side of the bay, each screwdriver has a tool bit in register with a respective screw-threaded fixing device when a respective side rail is in the second datum position. 
   A respective actuator is provided for advancing each screwdriver towards the respective side rail such that the tool bit engages the respective screw-threaded fixing device, rotation of the tool bit causing the screw-threaded fixing device to be advanced into the screw-threaded hole in the respective edge of the disk drive whereby the side rail is retained tight against the edge of the disk drive, and for thereafter retracting the screwdriver. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the present disclosure will now be described with reference to the accompanying drawings, in which: 
       FIG. 1  is a front view of a jig assembly according to a preferred embodiment of the present disclosure; 
       FIG. 2  is a front view of an embodiment of the jig assembly of  FIG. 1  with a loaded disk drive and side rails; 
       FIG. 3  illustrates an embodiment of the act of loading the disk drive side rails into the jig assembly of  FIG. 1 ; 
       FIG. 4  illustrates an embodiment of a prepared disk drive being withdrawn from the jig assembly of  FIG. 1 ; 
       FIG. 5  is an embodiment of an underside view of the jig assembly of  FIG. 1 ; and 
       FIG. 6  is a diagram of an embodiment of the pneumatic control circuit of the jig assembly of FIG.  1 . 
   

   DETAILED DESCRIPTION 
   Referring to the drawings, the jig assembly is designed to automatically screw two side rails  10 ,  FIGS. 3 and 4 , to respective opposite side edges  14  of a hard disk drive (HDD)  16 , each side rail  10  being affixed using two captive screws  12 . 
   The jig assembly comprises a bay  20  recessed into the front panel  22  of a rack or framework (not shown). The bay  20  is adapted to receive the HDD  16  “letterbox” style, the HDD  16  being slid in from the front of the bay on a steel base plate  23  (FIG.  5 ). This substantially reduces “head slap”. Opposite sidewalls  24  of the bay are stepped and the HDD  16  is received snugly between the more closely spaced upper parts  24   a  of the sidewalls, as seen in FIG.  2 . At its rear the bay  20  has a pneumatic limit switch S 1 . The switch S 1  is closed when the HDD  16  is pushed fully home in the bay  20 —this defines the datum position of the HDD  16  in the bay  20 . 
   The lower parts  24   c  of the stepped sidewalls  24  are displaced outwardly relative to the upper parts  24   a  and are joined to the latter by horizontal transition parts  24   b.  A respective side rail support member  28  is disposed below each transition part  24   b  in the recess formed by the outwardly displaced parts  24   c  of the sidewalls  24 . The support members  28  are elongated in the front-to-rear direction of the bay  20  and have a generally C-shaped cross-section. They are substantially parallel to one another and each has upper and lower longitudinal grooves  30   a,    30   b  respectively. 
   Each support member  28  is mounted on a pair of guide rods  32 ,  FIG. 5 , for movement towards and away from the opposite side edges  14  respectively of an HDD  16  accommodated in the bay  20 , i.e. in the direction of the double-headed arrows in FIG.  1 . and is also coupled to the piston  34  of a respective single-acting pneumatic cylinder C 2 . Each support element  28  receives and retains a respective side rail  10 , the side rail  10  being slid in from the front of the bay  20  and the upper and lower edges thereof sliding in the respective grooves  30   a ,  30   b . Initially, when the side rails  10  are slid in, the support members  28  are retracted against the lower sidewall parts  24   c , as seen in  FIG. 1. A  further pneumatic limit switch S 3  or S 4  at the rear end of each support member  28  is closed when the respective rail  10  is pushed fully home in the support member  28  which defines the datum position of each HDD side rail  10  in the bay  20 . 
   As stated, each side rail  10  has two captured screws  12 . When the HDD  16  and rails  10  are in their datum positions, the screws  12  are in register with corresponding screw-threaded holes (not shown) in the side edges  14  of the HDD  16 . The heads  12   a  of the screws are also in register with respective holes  29  ( FIG. 1 ) in the support members  28 , so that the screw heads  12   a  can be accessed from the other side of the support member  28  through the holes  29 . 
   On each side of the bay  20  a pair of pneumatic screwdrivers  40  are clamped in a pair of stocks  42 , FIG.  5 . The screwdrivers are of the type sold by Uryu of Japan under the model number US-LT20. Each pair of stocks  42  (and correspondingly the screwdrivers  40  clamped therein) is mounted on a pair of guide rods  44  for movement towards and away from the respective support members  28 , and is also coupled to the piston  46  of a respective double-acting pneumatic cylinder C 1 . The tool bits  48  of the screwdrivers are aligned with the respective holes  29  ( FIG. 1 ) in the support members  28 , so that the screw heads  12   a  can be engaged by the tool bits  48  through the holes  29  when the screwdrivers are advanced towards the support members  28 . 
   In operation of the jig assembly, the HDD  16  and side rails  10  are loaded into the bay  20  as previously described, the HDD  16  being slid on the base plate  23  and the rails  10  being slid in the support members  28 . As soon as the last of the three pneumatic switches S 1 , S 3  and S 4  is closed, indicating that the HDD  16  and both side rails  10  are in their datum positions, a pneumatic control circuit ( FIG. 6 , to be described) automatically actuates the pneumatic cylinders C 1  to drive the stocks  42 , and hence the screwdrivers  40 , inwardly towards the HDD  16  (at the same time, the control circuit supplies pneumatic pressure to the screwdrivers  40 ). 
   At some point each tool bit  48  will engage a respective screw head  12   a  and the screwdrivers react to the pressure of bearing against the screw heads  12   a  and begin to turn. As the tool bits  48  turn, the screws  12  are driven into the respective screw-threaded holes (not shown) in the side edges  14  of the HDD  16  so that each rail  10  is drawn towards the HDD  16 . This in turn also draws the support members  28  within which the rails  10  are retained towards the HDD  16 . The screwdrivers  40  are set to switch off automatically at a pre-determined torque limit when the rails  10  are screwed tight against the side edges  14  of the HDD  16 . The control circuit causes the cylinders C 1  to retract the screwdrivers  40  automatically after a pre-determined time period has elapsed. This time period, which is set by a pneumatic timer T 1 , is sufficiently long to enable the screws  12  to be tightened as aforesaid. 
   The operator is now free to withdraw the prepared disk drive, which he does by sliding the HDD  16  with affixed side rails  10  as a unit out of the bay  20 , FIG.  4 . In doing so, a further pneumatic limit switch S 2  located towards the front of the bay  20  is de-actuated having been actuated on insertion of the rails  10 . This automatically causes the control circuit to drive the cylinders C 2  to retract the now vacant support members  28  back to their original positions ( FIG. 1 ) whereupon the HDD preparation cycle is complete. 
     FIG. 6  is a diagram of the pneumatic control circuit used to control the jig assembly of  FIGS. 1  to  5 . In  FIG. 6 , C 1  and C 2  are pneumatic cylinders, V 1  and V 2  are double pilot 5/2 valves, V 3  and V 4  are single pilot 5/2 valves, T 1  is a pneumatic timer, and S 1  to S 4  are mechanically-operated pneumatic 3/2 limit switches. P stands for pressure supply, the ground symbol is atmospheric pressure (vented), and the T symbol means a closed inlet/outlet. 
   When each of switches S 1 , S 3  and S 4  are closed, indicating that both the rails  10  and the HDD  16  have all been inserted in the bay  20  to their datum positions, P will be connected to the A outlet of each switch in sequence so providing pressure at the outlet A of S 4 . This causes valve V 2  to vent outlet B and so allows the cylinders C 2  to float. This enables the support members  28  to be drawn, with the rails  10 , towards the edges  14  of the HDD. 
   When the prepared drive is withdrawn from the jig assembly, the switches S 1 -S 4  spring open, so connecting the outlet A of S 4  to atmospheric pressure. S 2  will be the last switch to spring open and causes the pressure from valve V 3  outlet B to switch valve V 2  so that pressure from valve V 2  outlet B retracts the cylinders C 2  (this will only happen when pressure is removed from the outlet of S 4  so venting the right pilot of V 2 ). 
   A pneumatic timer T 1  operates by bleeding the air pressure from the A outlet of S 4  until the timer switches over after a set period. This period is the time after insertion of the disk drive into the jig when the screwdrivers will be retracted and during this period the outlet of T 1  is vented. 
   The valve V 4  is needed to vent the left pilot of V 1  to allow the timer T 1  to actuate the right pilot of V 1  and so cause the cylinders C 1  to retract. Thus, before T 1  switches, the top pilot for V 4  is vented and so the spring on the other pilot channels the pressure supplied from S 4  to the left pilot of V 1  to cause the screwdrivers  40  to extend as soon as pressure is supplied from S 4  on initial insertion. 
   Variations of the pneumatic circuitry are possible; for example, a pneumatic reset switch can be included so that, for example, if an operator inserts a drive without correctly inserting the rails, cylinders C 1 , C 2  can be retracted to their home positions. 
   The advantages of the above embodiment are that, save for the manual withdrawal of the complete HDD, it is fully automatic once the components are properly loaded into the jig assembly. No external controls require to be activated to initiate the assembly cycle. It will also be seen that only a pneumatic supply is required to operate the jig assembly—no electrical elements (power or controls) are required. 
   The jig assembly described above directly confers a 75% reduction (from 40 sec to 10 sec) in HDD preparation time and reduces shock induced by the assembly of the rails to below measurable levels (from 90G to less than 10G). This materially reduces the level of HDD failure in the field. 
   The disclosure is not limited to the embodiment described herein which may be modified or varied without departing from the scope of the disclosure.