Steady rest
It is already known to detect the position of a pressure element of a steady rest, by means of which its angle levers are actuated, via a traction cable and its rolling position. Possible penetration of liquid via openings in the housing, present for functioning, is avoided by applying sealing air which generates a positive pressure in the housing. After operation, however, penetrated or penetrating liquid could damage the coiling device of the traction cable and impair the position detection. The present invention is intended to provide the option to provide a more accurate and simpler detection of the position of the pressure element, and thereby further alleviate the problem of penetrating liquid. This is achieved by use of a distance sensor that detects the position of the pressure element and is drained via a drain hole. During operation the drain hole is closed via a sealing air-actuated discharge valve, so that during operation the sealing air cannot escape through the drain hole, but in the rest state, any liquid that has still penetrated drains off.
1 . A steady rest for holding a workpiece on a machine tool, comprising:
a perpendicularly movable actuating piston having a first angle lever disposed at a first side of the actuating piston and a second angle lever disposed at a second side of the actuating piston and which within a housing cooperates with the first angle lever and the second angle lever via a pressure element,
a first sealing air connection coupled to the housing and operable to introduce sealing air into the housing to produce a positive pressure for avoiding penetration of liquid into the housing,
a distance sensor disposed below a lowest movement position of the pressure element for detecting a position of the pressure element, and
a drainage housing mounted at a lowest point of the housing and which opens into the housing via a run-up cavity for draining liquid from the housing via a drain hole that is closeable via a sealing air-actuated discharge valve.
2 . The steady rest according to claim 1 , wherein the distance sensor is oriented in parallel to the actuating piston, and the pressure element has a reflective surface, opposite from the distance sensor, for reflecting a distance signal emitted from the distance sensor.
3 . The steady rest according to claim 1 , wherein the discharge valve comprises a spring-actuated blocking piston, which in an unpressurized state opens up the drain hole.
4 . The steady rest according to claim 3 , wherein a second sealing air connection separate from the first sealing air connection is coupled to the blocking piston.
5 . The steady rest according to claim 3 , wherein the blocking piston is connected to a housing part that is acted on by sealing air.
6 . The steady rest according to claim 1 , wherein the distance sensor, the run-up cavity, the drain hole, and the discharge valve are accommodated in the drainage housing that is detachable from the housing.
7 . The steady rest according to claim 1 , wherein the first sealing air connection is disposed at a low point of a housing cavity formed in the housing.
8 . The steady rest according to claim 1 , wherein the first sealing air connection is coupled to the drainage housing.
9 . The steady rest according to claim 1 , wherein the distance sensor is an ultrasonic sensor.