Drawing installation for a press

摘要

A drawing installation for a press which has to produce the holding force for the counter-holding during the drawing. The drawing ram displaces the sheet metal part and the sheet metal holder against the holding force to be produced by the drawing installation and must additionally overcome the inertia forces which occur as a result of the acceleration of the parts of the drawing installation at the beginning of the deformation of the sheet metal part. In order to avoid the forces which occur thereby impact-like, the piston rod transmitting the holding force is pre-accelerated in the drawing direction prior to the contact of the drawing ram on the sheet metal holder. The piston rod has an operating surface adapted to be acted upon in the drawing direction. The pressure space coordinated to the operating surface is adapted to be connected with a pressure quantity space of a pre-acceleration cylinder and with a reservoir by way of a follow-up control. The control with respect to time of the pre-acceleration cylinder and of the refill from the reservoir takes place in dependence on the movement of the drawing ram, controlled by the press. The drawing installation is utilizable in presses with mechanically driven drawing ram and a sheet metal holder holding the sheet metal part.