QForm and its less expensive little brother QForm Lite are well suited for the simulation of heading operations typical of the fastener industry. QForm can utilize partial symmetry in 3D forgings to simulate typical fasteners with some 3D detail in the head such as hex head bolts. This allows simulations to run significantly faster. The transfer from one die to the next can be completely automatic so that the simulation runs from the first station to the last station automatically. The program can predict non fill, laps and cold shuts as well as fracture.
Cold forging has some restrictions related to higher forming forces and tool durability. The use of QFORM makes it possible to optimize material flow while reducing the force and utilizing the plasticity resource completely. QFORM can utilize composite tools, making it possible to optimize composite pre-stressed dies with hard-alloy inserts and shrink rings.
FRACTURE CAUSED BY ACCUMULATED DAMAGE
The following example illustrates QForm’s ability to track accumulated damage in a cold forged cap made of 1040 steel where a fracture has occurred in the third blow as seen below.
The adaptive damage model was applied to material particles shown as tracked points in the grid. Tracked points and grid are shown below in the billet and three blows:
The accumulation of damage is calculated in each tracked point
according to the evolution of stress state index and strain.
The most intensive accumulation of damage factor occurs in the first and third strokes and the critical factor (line1) was exceeded during the third stroke as seen below. This means that irreversible damage factor accumulation caused the fracture in blow three.