Punching tool die

#The invention relates to punching or stamping tools.

#In stamping tools with a punch and die, for example for punching holes in sheet metal, it is necessary to allow for a clearance between the punch and the walls of the die. The removed waste part of the sheet however tends to adhere to the punch, especially when the sheet must be slightly lubricated. These waste pieces may then fall from the withdrawn punch and produce marks in the following sheet being punched, which damages the sheet and may even make it unusable.

#Various expedients have been employed to prevent the waste pieces from adhering to and being withdrawn with the punch.

#An embodiment of the invention is shown, by way of example, in the single FIGURE of the accompanying drawing which is an axial cross-section of a die with its punch shown in elevation.

#The illustrated die 1 is part of a multiple matrix of a turrethead press and cooperates with a punch 1 whose end is schematically shown and has a smaller cross-section than through-hole 3 of the die 1. The die 1 has an upper surface for supporting a workpiece (not shown) in the form of a sheet, and a hollow underneath part 4 in which is lodged a body 5 formed from a solid mass of synthetic material, for example that available under the Trade Mark Araldite. Body 5 has an axial through hole 6 in extension of the hole 3 of die 1 but of smaller cross-section substantially equal to the cross-section of punch 2.

#The hole 6 is obtained by inserting the punch 2 fully in the hole 3 of die 1 while the die is inverted, pouring liquid Araldite (Trade Mark) into the hollow part 4 so that it surrounds the punch 2, and withdrawing the punch 2 when the mass has solidified sufficiently.

#The body 5 could alternatively be of other synthetic materials such as Nylon, Teflon (Trade Mark), PVC or synthetic rubber. It is also possible to use a hardened rubber, a metal or a metal-based material, such as that available under the Trade Mark DEVCON which is in pasty form and hardens when exposed to air. It is also possible to use a mixture of the mentioned products.