GB974253A - Automatic radioactive sample changer - Google Patents

Abstract

974,253. Handling radio-active material. ATOMIC ENERGY OF CANADA Ltd. June 1, 1962 [July 21, 1961], No. 21272/62. Heading B4Q. An automatic sample changer for moving radio-active samples 15 between a storage station 10 having upper and lower shielded chambers 13, 14 and a counting station 11 including a lead castle 16 containing counters 17, 18, comprises a slide 20 having an aperture for receiving a sample, the slide being reciprocated in a track 22 by a linkage 30, 32 driven by a member 34 carried by a rotatable member 28. One revolution of the member 28 in either direction causes the slide aperture to be moved from a storage position in alignment with the chambers 13, 14 to a counting position within the castle 16 and to return to the first-mentioned position. A reversible motor 26 drives the member 28 through gearing 27 and a one-way clutch including a spring-biased pawl (Fig. 8, not shown) so that the slide 20 is normally reciprocated only when the motor is driving in the forward direction; the clutch may, however, be overridden so that the slide is reciprocated for both forward and reverse driving of the motor. The samples 15, which are stacked within the chambers 13, 14, are transferred singly into the slide aperture by a plunger 36 attached to a lead screw 37 axially moved by a nut 38 driven by a chain 40. The chain is driven by the motor 26 through a gear 42 coaxial with the member 28, the arrangement being such that operation of the motor sufficient to rotate the member 28 through one revolution causes the plunger 36 to be moved a distance equal to the thickness of one sample 15. When the motor 26 is driving in the forward direction the plunger 36 moves downwards whereas when the motor is reversed the plunger moves upwards. In operation all the samples are initially stacked in the chamber 13 and the motor 26 is operated in the forward direction, whereby the slide 20 transfers a sample into the castle 16, a time switch 45 operated by a cam 44 on the link 32 causing the motor circuit to be interrupted for a predetermined period of time to enable the counting to take place. When the sample arrives back at the station 10 it drops into the chamber 14 on to the plunger 36 and the next sample is received in the slide aperture. When the last sample leaves the chamber 13, a switch (Fig. 5, not shown) is operated and the cycle continues as before until a switch 46A is closed by the link 32, whereupon the motor 26 is reversed. The clutch driving the member 28 now slips so that the plunger 36 lifts the stack of samples back into the chamber 13. However, if the clutch is overridden the slide 20 is also operated and the samples are returned to the chamber 13 after a second counting in the castle 16. When the last sample leaves the chamber 14, a switch (Fig. 6, not shown) is operated and the motor is again reversed.