Abstract:
A capper/de-capper system  1  has a rack support  10  for supporting a rack  11  containing a plurality of capped tubes  31  in a given position. A head unit  12  supports a two-dimensional array of capping/de-capping spindles  13 , each of which includes a clutch  133  and a capping/de-capping spigot  131  or socket, the spindles being aligned with the tube positions defined in the rack. A drive mechanism  108  moves the tubes and the head unit relatively towards and away from one another in use, when a rack containing capped tubes is disposed in the rack support, causing engagement and disengagement of the capping/de-capping spigots or sockets with and from the tube caps  32 . A spindle drive system  15 - 22  provides simultaneous rotation of the capping/de-capping spigots or sockets together after engagement with the caps, either to detach caps from the tubes or attach caps to the tubes.

Description:
BACKGROUND 
       [0001]    The present invention relates to a capper/de-capper device and method for attaching and removing caps from tubes, and, more particularly, a device and method for removing screw-threaded caps from tubes such as microtubes used in laboratories or micro-biological systems. 
         [0002]    High value biological samples are often stored and processed using so-called SBS format racks containing a plurality of tubes. Such racks may contain, for example, 96 tubes in an array of 8 by 12 apertures designed to hold the tubes securely. The tubes and their contents may be manoeuvred in a processing system, for example between a cold store and various processing stations and may be required to be filled (partly or fully) or processed simultaneously or individually. 
         [0003]    Conventionally, capping/de-capping has either been carried out by hand or else by means of a capping/de-capping unit individually engageable with the tubes either while they are still held in the rack or else after they have been separated from the rack. This is not only tedious (in the case of manual capping/de-capping), but also slow as it is usual for plural tubes to require processing in the same way at the same time. 
         [0004]    It is known to provide a linear array of cappers/de-cappers to allow capping/de-capping of a row of tubes, but such systems have been bulky as a result of the dimensions of the drive mechanisms of the capper/de-cappers, the close spacing of the tubes requiring the drive mechanisms of the cappers/de-cappers to be remote from the capper/de-capper heads and disposed over a larger footprint than the rack because of their size. 
         [0005]    The present invention is aimed at overcoming these problems and providing a capper/de-capper which can cap or de-cap a two-dimensional array of tubes simultaneously. 
       SUMMARY OF THE INVENTION 
       [0006]    According to the present invention therefore a capper/de-capper system comprises a rack support for supporting a rack containing a plurality of capped tubes in a given position;
       a head unit supporting a two-dimensional array of capping/de-capping spindles, each including a clutch and a capping/de-capping spigot or socket, the spindles being aligned with the tube positions defined in the rack;   a drive mechanism for moving the tubes and head unit relatively towards and away from one another in use, when a rack containing capped tubes is disposed in the rack support, to cause engagement and disengagement of the capping/de-capping spigots or sockets with and from the tube caps; and   a spindle drive system for causing simultaneous rotation of the capping/de-capping spigots or sockets together after engagement with the caps, either to detach caps from the tubes or attach caps to the tubes.       
 
         [0010]    A particular advantage of the clutch system of the capper/de-capper and method according to the invention is that, regardless of the number of tubes disposed in a given rack, the same capping torque can be applied to all caps. 
         [0011]    The tubes may be arranged, in use, to be moved towards or away from the head unit. Preferably, the rack support is driven upwardly and downwardly, but alternatively, the head unit may be movable towards or away from the tubes in use. 
         [0012]    The spindle drive system preferably includes a drive plate arranged to be movable upwardly and downwardly with respect to the spindles and in screw-threaded engagement therewith to cause simultaneous rotation of the spindles on movement relative thereto. 
         [0013]    The clutch on each spindle is preferably a spring-wrap clutch. Alternatively, the clutch on each spindle may comprise a pair of toothed dogs arranged to slip in one direction when the torque exceeds a given limit overcoming the spring-loading. 
         [0014]    The rack support may include a plurality of locking pins engageable with individual ones of the tubes in a rack in use, to hold the tubes in fixed position within the rack. 
         [0015]    The locking pins may be engageable upwardly through the rack support and rack into engagement with the tubes. 
         [0016]    The invention also includes a method of de-capping a plurality of tubes disposed in a rack, the method comprising
       placing a rack containing a plurality of capped tubes on a rack support at a given position;   moving the rack support and a head unit supporting a two-dimensional array of capping/de-capping spindles, each including a clutch and a capping/de-capping spigot or socket, relatively towards one another to cause engagement of the capping/de-capping spigots or sockets with the tube caps; and thereafter   causing simultaneous rotation of the capping/de-capping spigots or sockets together to detach the caps from the tubes.       
 
         [0020]    The invention also includes a method of capping a plurality of tubes disposed in a rack, the method comprising
       placing a rack containing a plurality of capped tubes on a rack support at a given position;   moving the rack support and a head unit supporting a two-dimensional array of capping/de-capping spindles, each including a clutch and a capping/de-capping spigot or socket holding a tube cap, relatively towards one another to cause engagement of the tube caps with the tubes; and thereafter   causing simultaneous rotation of the capping/de-capping spigots or sockets together and with the caps to attach the caps to the tubes.       
 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    Two examples of a capper/de-capper device according to the present invention will now be described with reference to the accompanying drawings in which 
           [0025]      FIGS. 1 to 17  of show an elevation of a first exemplary system at various stages during a possible operating cycle; 
           [0026]      FIG. 18  shows the top part of a pair of adjacent spindles, one partially sectioned, in further detail; and 
           [0027]      FIG. 19  shows an elevation of a second example. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    The capper/de-capper system  1  shown in the drawings comprises a standalone system for capping and uncapping screw-cap tubes and is designed as a bench-top system for use in either a laboratory or within a micro-biological control cabinet. 
         [0029]    The system  1  includes a rack support  10  which is dimensioned, in this example, specifically to receive a standard 96-well SBS format rack  11  (see  FIG. 2 ) in a defined and fixed horizontal position relative to a head unit  12 . 
         [0030]    The head unit  12  includes 96 capping/de-capping spindles  13  arranged in an 8 by 12 two-dimensional array. 
         [0031]      FIG. 18  is series of views of one of the spindles  13  shown in more detail. It can be seen that the spindle  13  includes a capper/de-capper spigot  131  which is spring-loaded by a compression spring  132  and rotatably driven through a clutch  133 . Each of the clutches  133  may comprise a spring wrap clutch as shown in  FIG. 18 , but various alternatives are possible and, for example, the clutch may comprise a pair of spring-loaded toothed dogs arranged to slip when the torque exceeds a given limit overcoming the spring-loading. 
         [0032]    In the spring wrap clutch  133  shown in the present drawings, a drive shaft  134  has a drive wheel  135  which is disposed as a friction fit within a socket  136  formed internally of a helical spring  137  which is integrally formed with a driven shaft  138 , the opposite end of which is in driving engagement with the capper/de-capper spigot  131 . A spherical bearing  139  disposed in the socket  136  provides a low-friction end stop for the end of the drive wheel  135 . When the drive wheel  135  rotates in one direction (for de-capping) the spring tightens against the drive wheel  135  to apply a higher torque than when it rotates in the opposite direction (for capping), when it loosens and slips when a lower, given torque is exceeded. The use of individual clutches ensures that each cap is tightened to the desired given torque to ensure that, on re-capping, the caps can be tightened to a torque, typically say 0.06 to 0.1 Nm, at which the tubes can be sure of being properly sealed. 
         [0033]    The head unit  12  mounts all 96 capping/de-capping spindles  13  by means of upper and lower bearing plates  14 ,  15 . The spindles  13  are rotatable together under the action of a motor  16  driving, via a gearbox  17 , pulleys  18  and  19  and a belt (not shown), a pair of drive shafts  21  (one at opposed corners of the top of the head unit) which are engaged with a drive plate  20  to drive the spindles  13 . To ensure that the drive plate  20  does not tilt, the alternate opposed corners slide on bearings along support shafts  22 . The drive plate  20  has threaded apertures in screw-threaded engagement with the drive shafts  21  and moves up and down as the shafts  21  rotate in one direction or the other. Similarly, the spindles  13  have a ‘fast’ screw thread and are in screw-threaded engagement with the other apertures in the drive plate  20  so that, as it is driven downwards, the spindles  13  rotate anti-clockwise and as it is driven upwards they rotate clockwise. 
         [0034]    The rack support  10  includes shoulders  101 ,  102  and a base plate  103  having a series of apertures  104 , the purpose of which will be described later. The rack support is mounted for vertical sliding movement between three positions (POSN 1 , POSN 2 , POSN 3 ) on shafts  105 , via sliding bearings  106  and a driven plate  107 , under the action of an electrically driven linear actuator  108  engaged with the driven plate  107  via a pair of support shafts  109  which have surrounding compression springs  110  mounted in retaining cups  111  on a second drive plate  112 . 
         [0035]    The second drive plate  112  includes upwardly extending locking pins  113 , one aligned with each aperture  104  in the base plate  103  of the rack support  10 , for use as described below. 
         [0036]    At the start of operation of a de-capping cycle, the system components are in the positions shown in  FIG. 1 . The rack support  10  is empty and is in its lowermost position POSN 1 . An operator (or a robot arm if the apparatus is used in an automated system) inserts a rack  11  into the rack support  10  as shown in  FIG. 2 , the rack support  10  defining the horizontal position of the rack  11  so that each tube  31  is vertically aligned with a corresponding spindle  13  of the head unit  12 . As can be seen from  FIG. 2 , each tube  31  includes a screw-threaded cap  32  and the bottom of the rack has corresponding apertures  23  which are aligned with the apertures  104  in the rack support base plate  103 . 
         [0037]    After insertion of the rack  11  into the rack support  10 , the operator initiates a de-capping sequence which causes the actuator  108  to lift the rack support  10  to the position POSN 3  as shown in  FIG. 3  until the caps  32  of the tubes  31  engage the bottom of the drive spigots  131  and start to compress the springs  132  in each of the drive spindles  13 . The spindles  13  are rotated during this process in a clockwise direction (when viewed from above) by upwards movement of the drive plate  20  so that, as the rack support continues to move upwards to the position POSN 2  as shown in  FIG. 4 , the spigots  131  engage in sockets (not shown) in the caps  32 . Not all of the caps  32  will be engaged by their respective spigots  131  at the same time and some of the spindles  13  will be compressed against the action of the springs  132  until the drive spigots align rotationally with the cap sockets, to ensure that all the caps  32  are located on respective spigots  131 . The clutches  133  allow a short period of overrun to be accommodated within those spindles whose drive spigots  131  engage first. The position POSN 2  is defined by stop collars  114  on the shafts  105  which prevent further upward movement of the rack support  10  by engagement with the upper ends of the sliding bearings  106 . The springs  132  are now compressed and the tubes  31  are prevented from upwards movement by the engagement of the caps  32  with the drive spigots  131 . 
         [0038]    The actuator  108  continues to lift the secondary drive plate  112  which causes compression of the springs  110  and inserts the locking pins  113  through the apertures  104  and into locking engagement between the sides of the tubes  31  as shown in  FIG. 5 . The tubes are now locked in place and the rack support  10  is lowered to the position POSN 3  as shown in  FIG. 6 , allowing the spindles  13  to extend under the action of the springs  132 , and the spindles  13  are then rotated anti-clockwise as the drive plate  20  is lowered, to unscrew the caps  32  from their respective tubes  31  as shown in  FIG. 7 , the clutches  133  tightening up to overcome any resistance to de-capping. As this occurs the spindle springs  132  accommodate the upwards movement caused by the unscrewing of the caps  32 . 
         [0039]    The rack support  10  is then lowered to the position POSN 1  as shown in  FIG. 8 , the caps  32  being retained on the spindles  13  as the tubes  31  are lowered in the rack  11  on the rack support  10 . The rack support  10  is lowered to the position POSN 1  defined by the collars  115  on the shafts  105  engaging the sliding bearings  106 . The actuator  108  is the fully retracted, disengaging the tube-locking pins  113  from the tubes  31  as shown in  FIG. 9 . A drip tray (not shown for clarity) may be slid automatically into position between the bottom of the caps  32  and the tops of the tubes  31  to prevent cross-contamination from droplets from one cap  32  dropping onto a tube other than that from which it has been removed. 
         [0040]    At this point the rack  11  with its associated tubes  31  can be removed by the operator for processing. For example further samples or active components may require to be inserted into the tubes  31  depending upon the particular process operating. 
         [0041]      FIG. 10  shows the start of a capping cycle in which a rack  11  of uncapped tubes  31  is inserted in the rack support  10 . The actuator  108  is operated as shown in  FIG. 11  to move the rack support  10  to the position POSN 3  so that the caps  32  retained on the spindles  13  engage with the top of the tubes  31 . The spindles  13  are then rotated clockwise by upwards movement of the drive plate  20 , re-capping the tubes  31  (see  FIG. 12 ), individually, to the desired torque as discussed above. As this proceeds the actuator  108  lifts the rack support  10  to the POSN 2  compressing the spindle springs  132  (see  FIG. 13 ) and the actuator  108  continues to move upwards in order to insert the locking pins  113  through the apertures  104  and into engagement with the tubes  31  as shown in  FIG. 14 . 
         [0042]    In the next step, see  FIG. 15 , the rack support is lowered to the position POSN 1 , removing the spigots  131  from the caps  32 , the tubes  31  being held within the rack  11  by means of the locking pins  113 , and thereafter, see  FIG. 16 , the actuator  108  is fully retracted, withdrawing the locking pins  113  and leaving the rack  11  (of now capped tubes  31 ) to be removed (see  FIG. 17 ). 
         [0043]      FIG. 18  shows a pair of adjacent spindles, one partially sectioned, in further detail. 
         [0044]      FIG. 19  shows a second example with the same components being identified with the same reference numerals for simplicity, and in which the primary difference is that, instead of the rack support  10  being movable vertically as in the example shown in  FIGS. 1 to 17 , the rack support is in a fixed position and all the vertical relative movement between the rack and the head unit  12  takes place by movement of the head unit  12 . 
         [0045]    Further differences are that the drive plate  112  and locking pins are dispensed with in the second example and to hold the tubes  31  within the corresponding rack  11  during disconnection of the capper/de-capper spigots  131  on the drive spindles  13  from the tube caps  32 , a stripper plate  140  is provided which can be moved downwardly into position when required, with the head unit  12  and which can be held in place by electromagnetic clamps (not shown) disposed beneath a stripper plate support plate  141 . The stripper plate  140  has bores  142  which are aligned with and through which extend the lower parts of the drive spindles  13 , the diameter of each of the bores being less then the diameter of the tube caps  32 . The stripper plate  140  is thus arranged to engage the tops of the tube caps  32  in use to prevent the tubes from  31  being lifted out of the rack  11  when the capper/de-capper spigots  131  are moved away from the rack to disengage from the tubes. 
         [0046]      FIG. 19  shows the head unit in a raised position and in this position a drip tray  150  is shown disposed beneath the bottom of the capper/de-capper spigots  131  so that, when caps  32  have been removed, the drip tray can be moved transversely into position beneath the caps held on the spigots  131  to catch an liquid droplets which would otherwise fall into the tubes or, when the rack has been removed, on to the base of the apparatus. 
         [0047]    A further difference lies in the use of ramp clutches  133  instead of the spring wrap clutches used in the first example. 
         [0048]    It will be appreciated that specific details of the system may be altered without departing from the concept of the invention.