US 4,335,498 AGranted

Machine tool

AssigneeTextron Inc.

InventorsRobert Z. Hague, Matthew F. Marsicano, Edwin F. Hantman

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Abstract

A machine tool having a spindle assembly associated with an indexing tool storage rack on which a number of distinct tools are stored, and a transport or tool carriage for conveying a selected tool between the storage rack and the spindle assembly; and including a control circuit for sequencing the operation of the various component parts of the machine tool for either manual or automatic operation. The spindle assembly includes a variable speed motor drive for rotating a spindle having a drawbar for releasably securing a tool adaptor with the tool to the end of the spindle and which is associated with a push rod operable to control the release of the tool adaptor during a tool changing operation. A spindle gear shifting assembly is operatively connected to the spindle for shifting of the spindle between direct high speed drive and back gear low speed drive or to a neutral position in which the spindle is disengaged from the variable speed motor drive. The arrangement is such that the machine tool is driven by a single AC motor and the various other component parts sequenced by fluid actuators. The invention further contemplates the utilization of a fluid actuated motor drive having a closed looped hydraulic circuit for controlling the operation of the tool carriage, including a vena contracta with means for expelling entrained air to prevent the system from being spongy.

A machine tool comprising a vertical spindle having a toolholder socket, a moveable storage rack having a plurality of circumferentially spaced sockets for receiving and storing thereon a plurality of toolholders, means for indexing said storage rack to a position accessible for effecting the removal of a toolholder therefrom;

an arm extending radially and substantially horizontal between said storage rack and said spindle, a toolholder carriage reciprocally mounted on said arm, a mechanical hand connected to said carriage, said hand having means for releaseably grasping a toolholder from said storage rack or spindle to remove it therefrom, and a drive means for effecting the drive of said carriage and mechanical hand carried thereby in an involute path toward and away from said spindle;
said drive means including a first and second cylinder disposed in tandem, a piston mounted in each of said cylinders for dividing each of said cylinders into a pair of complementary expandable chambers, a common piston rod interconnecting said pistons, means for alternately directing an actuating fluid under pressure into one or the other of said complementary pair of expandible chambers of said first cylinder;
means defining a closed hydraulic circuit connected between the expandible chambers of said second cylinder, said closed hydraulic circuit including a valveless vena contracta orifice interposed in said circuit between said other pair of complementary chambers, said vena contracta orifice having its smallest restriction free of any obstruction whereby the velocity of the piston rod responsive to the displacement of the piston due to the pressure of the actuating fluid thereon is determined by the free flow of fluid through said vena contracta orifice in said hydraulic circuit, a reservoir for containing a supply of said hydraulic fluid, and means connecting said reservoir in communication with the smallest restriction of said vena contracta orifice.

Abstract

Claims9