In a device for feeding articles, cylindrical feed screws having left and right hand pitched helical grooves are arranged in parallel and are driven rotationally in opposite directions such that an article deposited in the space between the roots of the grooves at one corresponding end of the grooves...http://www.google.es/patents/US6213185?utm_source=gb-gplus-sharePatente US6213185 - Feeder for outserts and other articles
