Steady rest

A steady rest for centering a rotationally symmetrical workpiece (2) in a space,

• the steady rest comprising:
• two housing halves (4, 5) disposed at a distance from one another and connected together,
• a plate-shaped middle piece (6) arranged between the two housing halves (4, 5), the middle piece (6) being mounted in the housing halves (4, 5) by means of an actuator piston (7) such that the middle piece is moveable in an axial direction (3) to the workpiece (2),
• two linear guide grooves (10) disposed in opposite large-surface end faces (6′) of the middle piece (6), with the linear guide grooves (10) running in a cross-shaped arrangement and at an angle to a movement direction (3′) of the middle piece (6),
• with two outer steady rest arms (11, 12), each of which is provided with a free end (14) mounted in one of the linear guide grooves (10) of the middle piece (6) in a movable arrangement,
• and a middle steady rest arm (13) attached to the middle piece (6) between the outer steady rest arms (11, 12),
• wherein
• two guide strips (15) are disposed between the two housing halves (4, 5) so as to be axially movable, parallel to, and at a distance from, a lengthways axis (3) of the two housing halves (4, 5), a control pin (22) is disposed projecting at right angles from each guide strip (15) and the control pin (22) faces the middle piece (6), first and second linear guide paths (43, 44) are disposed in the middle piece (6) and spaced apart from one another and disposed in parallel to the lengthways axis (3), and each in line with one of the control pins (22), that a curved control cam (41, 42) is disposed in the free ends (14) of the two outer steady rest arms (11, 12) with each of the control cams (41, 42) extending partially in line with one of the control pins (22), and one of the guide paths (43, 44) of the middle piece (6), the control pins (22) engaging the control cams (41, 42) while the middle piece (6) is moved in a direction of the workpiece (2), the control pins (22) on the inside of the control cam (41, 42) making contact with the workpiece (2) immediately before the steady rest arms (11, 12, 13), the control cams (41, 42) have being provided with a control surface (46) running outwards by means of which the outer steady rest arms (11, 12) are moved outwards for movement of the steady rest arms (11, 12) to the workpiece (2), positions of the guide strips (15) being adjustable in relation to a distance between the guide strips and the workpiece (2) to be clamped, the adjustment taking place by means of a first half shell (18) having a sickle-shaped cross section, and in such a manner that the two outer steady rest arms (11, 12) reach an active connection with the workpiece (1) at the same time as, or offset from, the middle steady rest arm (13), and the positions of the two guide strips (15) being adjustable from an aligned starting position in opposite directions synchronous to one another by means of a second curved half shell (19) with a sickle-shaped cross section.