Patent ID: 9566635
Date: 2017-02-14
CPC Classifications: B21D,B30B,F16P

Claim:
1. A device for preventing a tool from breaking during fine blanking or forming in a press that includes a ram and a fine blanking head, the ram being driven by a drive system and carrying out a stroke movement between top dead center and bottom dead center, the fine blanking head being disposed above the ram and having a main cylinder in which a V-ring piston located on a stroke axis is accommodated, the V-ring piston contacting plurality of V-ring pressure pins that are disposed coaxially to the stroke axis and axially guided in a top plate attached to the main cylinder and that are supported on a V-ring pressure plate, the V-ring pressure plate contacting the top plate, and together with the V-ring piston and the V-ring pressure pins, forming an axially displaceable structure for a cutting, forming and stripping operation, wherein the fine blanking head is connected to a hydraulic system for generating pressures acting on the tool by way of valves that can be actuated by a computer, the device comprising: an exchangeable plate suspended from the top plate, a sensing device disposed in the V-ring pressure plate; a sensor disposed in the top plate; hydraulic clamps for holding the exchangeable plate; hydraulic guides for guiding the exchangeable plate; wherein the exchangeable plate is held by the hydraulic clamps, in a lower end position without contact a lower surface of plate; wherein in an upper end position the exchangeable plate can be connected to and re-detached from the lower surface of the top plate as a function of a stripping operation of a scrap web from the V-ring pressure plate; wherein the exchangeable plate can be transferred from the lower into the upper end position by a movement of the ram and from the upper into the lower end position due to gravity; wherein a sensing distance that is adapted to a brake path of the drive system is provided between the top plate and the exchangeable plate, the sensing distance being sensed by the sensing device, which is disposed in the V-ring pressure plate and which outputs a signal to the computer for stopping the drive system and for deactivating the hydraulic system via the sensor disposed in the top plate in the event of a premature movement of a pressure plate disposed in the exchangeable plate.