Gas cylinder actuator with overtravel safety device

1. A gas cylinder actuator with overtravel safety device, comprising a tubular jacket for gas containment, which is closed hermetically at one end by a bottom provided with a gas filling valve and at the opposite end by a head portion, which is provided with a hole for the passage of a stem with a piston, said jacket, said bottom and said piston forming a gas expansion and compression chamber, first dynamic sealing means being interposed between said stem and said head portion of said tubular jacket, said bottom being axially movable with respect to said jacket and second sealing means being interposed between said bottom and an internal surface of said jacket that surrounds said bottom, said jacket being a control element for controlling the descending motion of a slider of a press with which the actuator is associated, said jacket being preset to selectively move with respect to said bottom in order to break or deform or render ineffective in general said second sealing means.

2. A gas cylinder actuator with overtravel safety device, comprising a tubular jacket for gas containment, which is closed hermetically at one end by a bottom provided with a gas filling valve and at the opposite end by a head portion, which is provided with a hole for the passage of a stem with a piston, said jacket, said bottom and said piston forming a gas expansion and compression chamber, first dynamic sealing means being interposed between said stem and said head portion of said tubular jacket, said bottom being axially movable with respect to said jacket and second sealing means being interposed between said bottom and an internal surface of said jacket that surrounds said bottom, said jacket being a control element for controlling the descending motion of a slider of a press with which the actuator is associated, said jacket being preset to selectively move with respect to said bottom in order to break or deform or render ineffective in general said second sealing means, said second sealing means being constituted by a sealing ring, which is accommodated in a corresponding annular slot formed perimetrically with respect to said bottom, the fixing of the bottom to the lower part of the jacket being provided by means of a locking ring, which is partially inserted in a first slot provided in the inner surface of the jacket and partly rested against a corresponding extraction-preventing shoulder provided on the outside of the bottom, said extraction-preventing shoulder being adapted to retain the bottom within the jacket, a lower edge of the jacket, which is in resting contact, having a reduced cross-section, so as to be able to deform in a controlled manner if subjected to a load by the slider, wherein the deformation by compression of the lower edge entailing the movement of the jacket, and therefore of its internal surface, with respect to the bottom, with at least partial separation of the sealing ring from said internal surface of the jacket.

3. The gas cylinder actuator according to claim 2 , wherein proximate to the shoulder, on the side opposite to the locking ring in an axial direction, there is provided a lightening slot which is adapted to render the shoulder breakable, wherein the failure of the shoulder for retaining the locking ring allowing the lifting of the jacket with respect to the bottom and an at least partial separation of the sealing ring from said internal surface of the jacket.