Abstract: A gripper for handling limp workpieces has piercing needles slanting downward on translatable needle bars. Slots in the needle bars slant parallel to the needles and engage stationary pins for constraining the needles to move axially. The needles mutually cross after piercing the workpiece to trap a portion thereof between themselves and a baseplate, thus gripping the workpiece securely without stressing or deforming it. An adjustment thimble with a venier scale limits the piercing depth of the needles. A rectangular housing facilitates juxtaposition of a number of such grippers, which may be conjointly controlled.

Abstract: A gripper head for the pick-up of a single piece of material from a stack of such pieces. The gripper head is provided with curved needles mounted on the ends of two concentric hollow cylinders. Each hollow cylinder comprises a spiral guide slit. The pitch direction of the guide slit of one cylinder is opposite the pitch direction of the guide slit of the other cylinder. The guide slits cooperate with the gripper head casing to produce rotation of the cylinders in directions opposite to one another during axial advancement of the cylinders within the casing. The cylinders are advanced within the casing by means of a pressure bolt connected to the cylinders. The magnitude of the advancement is determined by the position of an adjustable stop ring located within the casing. In operation, the two sets of curved needles extend from the casing edge and simultaneously rotate in opposite directions in an adjustable and retractable fashion.