Abstract: A die and backing block assembly with a quick release fastening arrangement which includes a plurality of connectors, each including a pin connected to the die and having a head insertable into a tubular body connected to a piston lodged in a cylindrical chamber formed in the backing block. The mouth of the tubular body has radial holes accommodating balls which hold the head of the pin in the tubular mouth of the piston under the action of elastic springs, which tend to move the piston away from the head of the pin. The die and the backing block connected to each other are released from each other when oil is injected under pressure into a volume between the bottom of the chamber and the piston. The piston moves towards the head carrying the balls into a seat so that the balls move and release the head of the pin thus allowing for a separation of the die from the backing block.