Method and device for the production of a stamping with almost smooth cutting and enlarged functional surface

A fine blanking apparatus that adjusts a state of stress in a cutting zone during fine blanking and forming of a stamping out of a flat strip so as to achieve the stamping with an almost smooth and enlarged functional surface, the apparatus comprising:

• a tool having an upper part and a lower part, and comprising among the upper part and lower part at least a shearing punch, a guide plate for the shearing punch, an ejector, another ejector, a cutting die, and a projection having one of either a V shape or a platform shape, said projection being arranged on the cutting die and being part of said lower part, wherein during operation, the flat strip is clamped between the guide plate and cutting die, and the projection is pressed into the flat strip;
• and
• at least one coaxial tool element, distinct from the shearing punch, acting on the flat strip in a same direction as the shearing punch and adjacent to an area of the flat strip acted on by the shearing punch, the at least one tool element being positioned to have a movement in a same direction as a direction of a cutting movement of the shearing punch while said tool element movement is retarded relative to said cutting movement of the shearing punch;
• and
• wherein the at least one tool element and the projection are positioned relative to each other to interact on the flat strip from opposing directions;
• wherein the shearing punch is configured to cut along a cutting line in a cutting zone during a cutting operation into the flat strip;
• wherein the cutting die is configured in opposition to said shearing punch to squeeze material during said cutting operation transverse to said cutting movement direction;
• wherein the at least one tool element is configured to move into the flat strip and to apply a controlled force to the flat strip that, together with the projection as a barrier to transverse retardation of material, reduces conversion of compression stress to tensile stress in the flat strip as the shearing punch progresses along the cutting line into the flat strip, thereby reducing development of tears and rollover in the stamping so as to achieve said almost smooth functional surface of the stamping.

A method for adjusting a state of stress in a cutting zone during fine blanking and forming of a stamping out of a flat strip so as to achieve the stamping with an almost smooth and enlarged functional surface, comprising:

• clamping the flat strip at closing between an upper part and a lower part, the upper part including a shearing punch, a tool element that operates parallel to a cutting line of the shearing punch, a guide plate for the shearing punch, and an ejector, the lower part including a cutting die having a projection thereon, an ejector and an inner form stamp;
• performing a cut in the cutting zone by first applying a position oriented compressive stress on the cutting zone between said upper and lower part with the tool element, then shearing through at a high compressive stress with the shearing punch and cutting die to complete the cut as part of said fine blanking;
• during said shearing at high compressive stress the cutting die squeezing material;
• and
• during said applying the position oriented compressive stress, the tool element moving parallel to a direction of cutting of the shearing punch penetrating into the flat strip to apply a controlled force in opposition to the squeezing of material by the cutting die to resqueeze the material in the cutting zone in a direction diagonal to the cutting line between the shearing punch and the cutting die, said projection positioned relative to the tool element to support transverse flow of material during said resqueezing;
• and
• wherein said tool element is configured to operate in parallel relative to the shearing punch during said fine blanking to reduce conversion of compression stress to tensile stress during said cut, thereby reducing development of tears and rollover in the stamping so as to achieve said almost smooth functional surface of the stamping.