Machine and a method for driving inserts into pieces of sheet metal

A machine for driving inserts into pieces of sheet metal, comprising:

• a punch and a die which are movable relative to one another along a substantially horizontal axis along which inserts are to be driven, wherein said punch and said die define a driving zone therebetween;
• a slidable support;
• a piece-holder head rotably attached to said slidable support and having at least one gripping member for gripping the piece of sheet metal under two different operative conditions;
• means for moving said at least one gripping member relative to said piece-holder head, such that said at least one gripping member holds the piece of sheet metal in a floating manner with respect to said piece-holder head under a first of said two different operative positions, so that the piece is free to undergo adjustment movements, relative to said piece-holder head, when the piece is acted upon by an external force;
• means for locking said at least one gripping member relative to said piece-holder head, such that said at least one gripping member holds the piece relatively rigid with respect to said piece-holder head under a second of said two operative conditions, so that said punch and die can cooperate to drive an insert into the hole in the piece of sheet metal;
• and
• a locating means for imparting an external force to the piece when the piece is held under the first operative condition, to cause the adjustment movements of the piece to align the hole, into which an insert is to be driven, with the axis along which the inserts are to be driven.