Patent Number: 047626658
Section: summary

This invention relates to the location of bodies end-to-end to form a stack of predetermined length. One application of the invention is in the formation of stacks of nuclear fuel pellets for loading into the sheath of a fuel pin. Because of variations in pellet length, difficulties may be encountered in securing the required stack length and, in the past, reliance has been placed on manual handling of the pellets so that the operator by trial and error can correct for drift away from the required length by substituting pellets in the stack with longer or shorter pellets depending upon whether the stack length is below or above the required length. Manual handling is considered undesirable since it tends to be time consuming and laborious and may, with certain types of nuclear fuel, such as reprocessed uranium or plutonium, give rise to radiological hazards for operators. The object of the present invention is to provide a method of and apparatus for automatically effecting stacking of bodies end-to-end to form stacks of predetermined length. According to one aspect of the present invention we provide a method of stacking bodies in end-to-end relation to form a stack of predetermined length said method including the steps of mechanically segregating said bodies according to length into a plurality of groups, initially drawing on said groups to build-up the stack part-way towards its overall length, measuring the length of the partly-formed stack and, depending on the extent (if any) to which the measured length deviates from a predetermined value, compensating for any such deviation by selecting between said groups in continuing to build up the stack. According to a second aspect of the invention we provide apparatus for stacking bodies in end-to-end relation to form a stack of predetermined length, said apparatus comprising means for feeding said bodies from a supply to a stacking zone, means upstream of the stacking zone for measuring the lengths into a plurality of lanes, means for measuring the stack length in said stacking zone and selector means responsive to said stack measuring means for selectively supplying bodies from said lanes to the stacking zone.