| CPC B22D 17/203 (2013.01) [B22D 17/2038 (2013.01)] | 12 Claims | 

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               1. A head assembly comprising: 
            a piston head for making a piston of a press for a die-casting machine, comprising: 
                a head body having a side wall extending around a head axis, and 
                  at least one ring seat obtained in the side wall and suitable to receive a respective sealing ring, the at least one ring seat forming a cylindrical bottom wall parallel to the head axis and being delimited by at least one annular shoulder obtained in the head body; and 
                a sealing ring housed in the at least one ring seat, wherein at least one gap is formed between said sealing ring and the at least one annular shoulder; 
                wherein: 
                a lubrication circuit is obtained in the head body and is suitable to facilitate the sliding of the piston in a respective container of the die-casting machine, 
                the lubrication circuit comprises at least one lubrication end duct leading into the at least one ring seat so as to be covered by the sealing ring, and 
                at least one lubrication end duct leads into a surface channel which runs through the bottom wall, said surface channel ending at a base of said at least one annular shoulder in order to convey a lubricant towards the at least one gap for the outflow of the lubricant from the at least one gap. 
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