Papers by Keyword: Die Deformation

Abstract: Die deformation has long been suspected to cause bad damages that are challenging to recover and have a straight impact on the quality of the final product. The forming industry would greatly be benefited if this mystery is faithfully uncovered. This study tries to investigate the effect of die deformation on the geometrical quality of the workpiece in terms of springback through finite element simulation. The forming process of a 1-m-long car chassis component made out of the HR420LA hot-rolled high-strength low alloy steel sheet with a thickness of 3 mm is particularly picked out to be examined. Therein, the mechanical properties of the steel sheet are neatly characterized through a group of uniaxial tensile tests. The two similar r-based Hill48 criteria are used to model the yield behavior of the steel sheet. The hybrid Ludwig-Voce strain hardening law is applied to account for the hardening during plastic deformation. The simulation results show that die deformation has a very limited effect on part springback as the evaluated dies are fairly rigid and hence deform very little by less than 0.25 mm. The effect of yield model variation is even negligible on part springback as the two chosen models are closely connected. Taking die deformation into consideration when designing new dies is unnecessary if the anticipated degree of deformation is not large enough.

Abstract: In this paper, non-isothermal analysis of an automatic multi-stage cold forging process of a ball-stud is conducted using a new material model which is a closed form function of strain, temperature and strain rate covering low and warm temperatures for high-strength stainless steel SUS304. An assembled die structural analysis scheme is employed for revealing the detailed die stresses, which is of great importance for process and die design for metal forming of the materials with high strengths. Die elastic deformation is dealt with to predict final geometries of material with higher accuracy. A complete analysis model is proposed to be used for optimal design of process and die designs in automatic multi-stage cold forging of high-strength materials.

Abstract: In the paper experimental investigations aimed at allowing a detailed and accurate comparison of different FEM codes were presented and discussed. Two hollow profiles within the same die were characterized by different thicknesses within the profile, two welding chambers and critical tongues (one fully supported and one partially supported). The material flow balance was performed by means of feeder size and position on a profile and by means of bearings on the other one. Accurate monitoring of process parameters was carried out by using a self-calibrating pyrometer for profile temperature, six thermocouples for die thermal monitoring, a laser velocitymeter for profile speed and two laser sensors for die deflection on critical tongues. AA6082 alloy was used as deforming material, while H-11 hot-work tool steel was selected for the die material. The experiments were repeated at least three times under the same conditions in order to provide a nearly steady state statistical distribution of the acquired data. These are used as a reference for the 2011 edition of the extrusion benchmark.

Abstract: In this paper experimental investigations aimed at measuring the die deformations during aluminum extrusion process is presented and discussed. A two-holes die generating two U-shape profiles with different supporting legs was produced and tested under strictly monitored conditions. The influence of die deformation on the speed, temperature distribution and distortion of the two profiles is reported and analyzed. AA6082 alloy was used as deforming material while H-13 hot-work tool steel was selected as die material. The experiments were repeated at least three times in the same conditions in order to achieve a statistical distribution of the acquired data: such data are then used as a reference for the 2009 edition of the extrusion benchmark.