Abstract: A crust breaking device for metal melts includes a pneumatic cylinder having a cylinder housing, a piston, which is axially displaceable within the cylinder housing, and a piston rod, which is fastened to the piston. The piston rod is guided by the cylinder housing and movable between a retracted final position and an extended final position. The device includes an electronic control unit and a valve arrangement, which can be actuated via the electronic control unit and is connected via control lines to front and rear pressure chambers inside the cylinder housing. The device further includes at least one metal plate that is fixedly arranged within the cylinder housing in order to define a final position of the piston or the piston rod. The metal plate and the piston are electrically connected to the control unit such that a contact of the piston with the metal plate closes a circuit.

Abstract: A crust breaking device for metal melts includes a pneumatic cylinder having a cylinder housing, a piston, which is axially displaceable within the cylinder housing, and a piston rod, which is fastened to the piston. The piston rod is guided by the cylinder housing and movable between a retracted final position and an extended final position. The device includes an electronic control unit and a valve arrangement, which can be actuated via the electronic control unit and is connected via control lines to front and rear pressure chambers inside the cylinder housing. The device further includes at least one metal plate that is fixedly arranged within the cylinder housing in order to define a final position of the piston or the piston rod. The metal plate and the piston are electrically connected to the control unit such that a contact of the piston with the metal plate closes a circuit.

Abstract: The invention relates to an arrangement for producing aluminium, comprising a cathodic vessel, anode means, an electricity source for generating a direct current between the cathodic vessel and the anode means in order to obtain molten aluminium from a bath, and a subassembly for breaking a crust formed in the area of the anode means during the production. Said subassembly encompasses a chisel which is operated by means of a pneumatic cylinder comprising a sensor for sensing the lift of a piston rod of the cylinder and is electrically connected to a terminal of an electronic unit. Another terminal of the electronic unit is connected to the cathodic vessel in order to generate an alternating current between the chisel and the cathodic vessel and measure the potential and/or the alternating current there-between. The chisel has means for forming an electrode in the bottom zone as well as electronic connecting means for connecting the electrode to one terminal of the electronic unit.