Patent GB-485546-A (GB)
Title: Improvements in nut tapping machine
IPC: B23G1/18
Filed: 1937-11-30
Abstract: 485,546. Nut-tapping machines. DEHN, F. B. (Waterbury Farrel Foundry & Machine Co.) Nov. 30, 1937, No. 33079. [Class 83 (iii)] In a double-tap-grip nut-tapping machine nuts are rotated by a chuck on a stationary tap having a long shank and after being tapped are moved along the shank by feeding means which separate the nuts into two sections with a space between so that further feeding means may enter the space to move the nuts in two stages past the top grips which are released alternately. The top shank 23 is gripped by two sets of jaws on levers 16, 18 which are oscillated by any known means synchronized with the nut feeding means and arranged so that the tap will not be released completely at any time. The nut blanks are supplied by means (not shown), to the rotary chuck 30 driven by a chain at 32 and carrying fingers 29 which rotate the blanks on the threaded portion 22 of the tap. The feeding means comprise a carriage consisting of arms 35, 36, the former sliding in a dove-tailed guide in the machine base 20 and the latter in a rectangular guide, and reciprocated by a rotary cam 41 and a lever 40. Fingers 58, 70 are mounted on the carriage for feeding the nuts past the grippers 16, 18, and further jaws 48 are mounted on a second carriage 43 to supply the fingers 58 with nuts from the tap 22. The carriage 43 is slidable on guide rods 44 attached to the base 20 and is moved towards the tap 22 by the arm 35 of the main carriage during part of its stroke, the return movement being effected by a spring 481. Fibre buffers are provided on the carriage 43 for engagement by the arm 35 to reduce shock and noise, and movement away from the tap is limited by shoulders 15 on the guide rods 44. The jaws 48 are pivoted at 49 on the carriage 43 and are drawn towards each other by a spring 51, this movement being limited by the heels of the jaws engaging adjustable abutments 54 on the carriage. During forward motion of the carriage 43 the jaws 48 wipe over some of the nuts which have just been tapped and the pointed ends of the jaws then engage the front face of a nut to move it and the nuts behind, during the rearward stroke, to a position in front of the grippers 18. A spring-controlled detent 76 is mounted on the frame adjacent the grippers 18 and engages the upper surfaces of the nuts to prevent them from returning with the jaws 48, so providing a vacant space on the tap shank into which the fingers 58 may project. The detent has a bevelled lower end which rotates all the nuts into a position having a flat face on top. A spring 72, adjustably secured to the frame at 75, prevents nuts from passing between the grippers 18 when these are open. The fingers 58, 70 are pivotally mounted on blocks 62 adjustably secured in the arms 35, 36 and are urged into the operative position shown by springs around their pivots. During forward motion of the main carriage the fingers wipe along guides 69, 691 attached to the grippers 18, 16 and the fingers 58 are thus guided past the nuts in front of the grippers 18. When the latter are opened, however, the grippers 16 remaining closed, the fingers 58 are released from the guides and project into the free space in front of the nuts so that on rearward movement of the main carriage this batch of nuts will be drawn between the open grippers to a position in front of the grippers 16. The latter are opened at the end of the next forward stroke of the main carriage and the fingers 70 are thereupon released from the guides 691 to engage the nuts between them so that on the rearward stroke of the carriage the nuts will be drawn between the grippers 18 and completely off the shank 23 of the tap. In a modification, the slidable detent 76 is replaced by a pivoted spring detent. Cutting, catching and removing.-The cuttings and cutting oil pass between the fingers 29 of the chuck onto a flaring recess 33 therein, and thence to an annular groove 34 in the machine frame from which they pass into a receptacle.