Device on tools or presses for drawing sheet-metal shaped parts

摘要

The device is equipped with a drawing cushion serving as a support for the blank holder and consisting of a plurality of hydraulically acting working cylinders and with a further drawing cushion for supporting at least one drawing punch movably guided in the drawing direction and consisting of at least one working cylinder. The working cylinder for supporting the drawing punch is in fluid connection with the working cylinders of the drawing cushion for supporting the blank holder and is supplied with the fluid pressure means displaced from the latter during the drawing operation. This actuates the drawing punch counter to the direction of movement of the blank holder, the drawing depth thus being the sum of a part-stroke of a drawing ring of the upper part of the tool, the said drawing ring moving downwards during the drawing operation, and of a part-stroke of the upward-moving drawing punch. A pressure sensor adjustable to a predetermined fluid pressure is arranged between the working cylinders of the two drawing cushions, the said working cylinders being in fluid connection, and is coupled to a signal transmitter which emits a signal which interrupts the drawing operation and, if required, reverses a drawing press when the set fluid pressure is exceeded. The pressure sensor can be set in dependence on the data of the drawn sheets used such that the drawing operation is interrupted at a fluid pressure lying at the tear limit of the drawn parts, with the result that before further drawing a ... Original abstract incomplete.