Feed mechanism for machine tool

Claim 2

In a feed mechanism for a machine tool with a feed table having a hydraulic cylinder, a piston slidably disposed in the cylinder and separating the same into two chambers, a shaft connected to one side of the piston and having a rack portion formed thereon, a drive connection including a pinion engaging the rack portion for moving the feed table, a piston rod connected to the other side of the piston, and means for selectively supplying and exhausting a pressure fluid from the respective chambers of the cylinder, the improvement comprising: screw shaft means axially adjustably threaded into the piston rod for permitting adjustment of the stroke of said piston; resiliently biased stop means positioned outside of said cylinder for engagement with the screw shaft means upon displacement of said piston in one direction and serving to mechanically limited the movement of said piston at one end position thereof; and valve means disposed on said stop means for controlling the exhausting of fluid from the cylinder chamber on said screw shaft side of said piston, for reducing the speed of the piston just before the piston reaches the end of its stroke, regardless of adjustment of the stroke of said piston.

Claim 3

A feed mechanism as set forth in claim 1, further comprising: graduations on the peripheral surface of said screw shaft means; and an indicator on said piston rod cooperative with said graduations on the screw shaft means for indicating the relative adjusted position therebetween.

Claim 4

A feed mechanism as set forth in claim 1, wherein said valve means is connected between a fluid source in said supplying and exhausting means and one of the chambers of said cylinder together with parallel lines having a check valve and a throttle respectively disposed therein.

Claim 5

A feed mechanism as set forth in claim 1, wherein said piston rod is in the form of a hollow cylindrical member projecting beyond said cylinder from one end thereof in sealed relation therewith; and said screw shaft means is threaded into said projecting end of said piston rod.

Claim 6

A feed mechanism for a machine tool having a feed table comprising: a hydraulic cylinder; a piston slidably disposed in said hydraulic cylinder and having a piston rod thereon; means connecting said piston and said feed table for moving said feed table in response to movement of said piston in said cylinder ; a fluid pressure supply; fluid control circuit means between said supply and the opposite sides of said hydraulic cylinder for selectively supplying fluid pressure to one side of said cylinder while simultaneously exhausting fluid from the other side for moving said piston in one direction and supplying fluid pressure to the other side of said cylinder while exhausting fluid from said one side for moving said piston in the opposite direction; a shaft axially adjustably disposed in said piston rod and having a portion thereof projecting beyond said piston rod; and stop means for said piston rod operable by said shaft portion for controlling the fluid control circuit means to reduce the speed of said piston, regardless of adjustment of the stroke of said piston, just before the piston reaches the end of its stroke in said cylinder and for mechanically limiting the movement of said piston at one end position thereof.

Claim 7

A feed mechanism for a machine tool having a feed table comprising: a hydraulic cylinder; a piston slidably disposed in said hydraulic cylinder and having a piston rod thereon; means connecting said piston and said feed table for moving said feed table in response to movement of said piston in said cylinder ; a fluid pressure supply; fluid control circuit means between said supply and the opposite sides of said hydraulic cylinder for selectively supplying fluid pressure to one side of said cylinder while simultaneously exhausting fluid from the other side for moving said piston in one direction and supplying fluid pressure to the other side of said cylinder while exhausting fluid from said one side for moving said piston in the opposite direction; a shaft axially adjustably disposed in said piston rod and having a portion thereof projecting beyond said piston rod; and stop means for said piston rod operable by said shaft portion for controlling the fluid control circuit means to reduce the speed of said piston, regardless of adjustment of the stroke of said piston, just before the piston reaches the end of its stroke in said cylinder and for mechanically limiting the movement of said piston at one end position thereof.

Claim 8

The feed mechanism set forth in claim 5, wherein said stop means comprises a movable stop member positioned in said fluid control circuit means; means normally urging said stop member in a given direction to permit fluid communication between said supply and one side of said hydraulic cylinder through said stop member; and said stop member being movable in the opposite direction by said piston rod for shutting off fluid communication between said supply and said cylinder through said stop member.

Claim 9

The feed mechanism set forth in claim 6, wherein said piston rod is a hollow member and said shaft is threadably engaged therein.

Claim 10

The feed mechanism set forth in claim 6, wherein said fluid control circuit means comprises another fluid communication path between said supply and said one side of said hydraulic cylinder parallel with said fluid communication path through said stop member, said another parallel path having a fluid flow restrictor therein.

Claim 11

The feed mechanism set forth in claim 8, wherein said fluid control circuit means comprises a third fluid communication path between said supply and said one side of said hydraulic cylinder, said third path having a check valve therein.