Machine to sort fur skins etc. into thickness ranges - uses radioactive source and detector to determine mean thickness of sheet

摘要

A machine for automatically sorting flat sheets of material into ranges of different thicknesses has a conveyor to advance each sheet in turn through a measuring head towards a set of collecting hoppers. Entry to each hopper is controlled by a pivoted shutter electrically operated by an automatic controller responding to signals from the measuring head w.r.t. reference signals. The measuring head employs a radioactive source on one side of the sheet and a detector on the other side and is located between two pairs of conveying rolls which simultaneously advance and stretch the sheet passing through the measuring head. The signal circuit determines the mean value of radiation intensity as the sheet passes through and transmits this to the reference signal comparator. The detector signal is also passed to a second instrument which transmits instantaneous thickness values to the source of the reference signals. The link between the second instrument and the source of reference signals passes through a switch and a memory element in series. Used for sorting flat sheets of material, such as fur skins before trimming, into a series of thickness ranges esp. rabbit skins. The skin is held in tension to avoid false readings due to folds. Average thickness over the advancing length of the skin ensure that a single, erroneous measurement does not result in incorrect sorting.