DISPOSITIF COMMANDANT L'AVANCE DE BARRES POUR TOUR AUTOMATIQUE MULTIBROCHES

Le présent perfectionnement concerne un dispositif servant à faire avancer des pièces sous forme de barres dans un tour automatique multibroches. Le cylindre à air comprimé 13 est muni d'une tige de piston 13' qui le traverse de part en part et dont l'extrémité opposée au tour automatique presse, au moyen d'un verrou 23 et d'une tige de poussée 24, le chariot d'avance 12 contre une plaque 25 qui est fixée à l'extrémité côté tour automatique du cylindre, tant que de l'air comprimé se trouve au raccordement A du cylindre. Ce perfectionnement a pour avantage de permettre le verrouillage entre le cylindre à air comprimé et le chariot d'avance moyennant l'emploi d'éléments relativement peu onéreux. In a combination of a multiple- spindle automatic lathe and a multiple-spindle bar material loading magazine, a device for feeding the bar material 16 from the magazine to the spindles 8 of the lathe comprises a feed block mounted in the lathe for reciprocating movement parallel to the axes of the lathe spindles 8, and a feed carriage 12a mounted in the loading magazine and adapted to cooperate with bar material carrying slides 1 of the loading magazine. The feed carriage 12a is operatively connected to the feed block via a coupling linkage 11, for synchronous of movement with the feed block. The linkage 11 cooperates with a pneumatic cylinder 13a mounted on the carriage 12a and acting as a link member between the coupling linkage 11 and the feed carriage 12a during the entire machining time of the bar material 16 in the lathe. The pneumatic cylinder 13a has a piston rod 13'a which extends through the cylinder 13a. The end of the piston rod 13'a which is remote from the lathe urges the feed carriage 12a by way of a yoke 23 and a push rod 24, against a plate 25, connected to that end of the cylinder 13a which is adjacent the lathe, as long as the cylinder is under pressure of compressed air which tends to move the cylinder 13a away from the lathe. The arrangement is such that after completion of the last workpiece from a respective bar 16 in a chuck 9 the feed block is stopped, the chuck 9 opened and the unmachineable bar residue 15 is pushed out of the chuck 9 by means of a fresh bar being actuated by the pneumatic cylinder 13a independently of the feed block as the fresh bar is fed in.