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Open access

Z. Gronostajski, M. Hawryluk, M. Kaszuba, P. Widomski, J. Ziemba and J. Smolik

Abstract

This study is focused on tools used in the industrial process of hot forging of a front wheel forging (gear wheel) manufactured for the automotive industry. Five different variants were applied for the tools: 3 die inserts were coated with three different hybrid layers (PN + PVD type), i.e. AlCrTiN, AlCrTiSiN and CrN, one insert was only nitrided, and one was pad welded, to improve tool durability. The tool wear was analysed and represented by the material degradation on the working surface, based on the 3D scanning and the material growth of the periodically collected forgings. Additionally, the scanned tools were divided into two areas, in which it was found, based on the analysis, that various degradation mechanisms are predominant. Microstructural tests and hardness measurements of the analyzed tools were also performed. Based on the results, it was found that, in the central part of the die insert, thermo-mechanical fatigue, abrasive wear and plastic deformation occurred, while in the area of the bridge insert, only abrasive wear could be observed. For these areas, the loss of material was determined separately. It was established that the use of the GN+CrN and GN+AlCrTiN hybrid layers on forging tools improves their durability, while the best results in the central area were observed on the tool with the GN+CrN layer, which is the most resistant to thermo-mechanical fatigue. In the second analyzed area, good wear resistance occurred on GN+CrN, GN+AlCrTiN and pad welded inserts, for which, together with the increase of the forging number, a proportional, slight growth of the loss of material occurred.

Open access

Z. Gronostajski, M. Hawryluk, R. Kuziak, K. Radwański, T. Skubiszewski and M. Zwierzchowski

The aim of the research was to determine the deformation condition of ECAP process of multiphase high strength aluminium bronze BA1032. The studies have indicated that it is possible to deform multiphase aluminium bronze BA1032 in the ECAP process at a temperature of 400°C and die angle Φ =110°. The deformation of the bronzes at lower temperatures encounters some difficulties - cracks appear which make repeated ECAP impossible. The cracks appear on the top surface of the samples where it contacts the surface of the outlet channel. FEM simulations show that the largest plastic strains occur in this area. The proposed ECAP method of large plastic deformations as applied to the investigated aluminium bronzes makes it possible to obtain very strong refinement especially of eutectoid α + γ 2.

Open access

Z. Gronostajski, M. Hawryluk, M. Kaszuba, A. Niechajowicz, S. Polak, S. Walczak and D. Jabłoński

Die Profile Optimization for Forging Constant Velocity Joint Casings

This paper presents the results of a search for an optimal shape of the die for forging CVJ (constant velocity joint) casings. The aim of the optimization was to increase tool life by reducing the pressures acting on the die. Therefore the minimization of the forging force was adopted as the optimization criterion. In order to verify the optimization results, the graphs of the calculated forging forces were compared with the real forging force registered by a dedicated measuring & archiving system.

Then new dies with the optimal shape obtained from the numerical modelling were made and used in the industrial forging process. It was found that the maximum forging force values for the optimized dies were by about 10-15% lower than the ones for the dies with the original shape, which indicates an increase in die durability.

Open access

Z. Gronostajski, M. Hawryluk, M. Kaszuba, G. Misiun, A. Niechajowicz, S. Polak and M. Pawełczyk

Abstract

This paper presents an analysis of the industrial process of hot forging a flange. The authors developed several thermomechanical models of the forging process for which they carried out computer simulations using the MSC.Marc 2013 software. In the Jawor Forge flanges with a neck are manufactured by hot forging in crank presses with a maximum load of 25 MN. The input material, in the form of a square bar, is heated up to a temperature of 1150°C and then formed in three operations: upsetting, preliminary die forging and finishing die forging. The main aim of the studies and the numerical analyses, in which the geometry of the tools would be modified, was to maximally reduce the amount of the input material taking into account the capabilities of the Jawor Forge, and consequently to significantly reduce the production costs. Besides the Forge’s equipment resources, the main constraint for modifications was the flange-with-neck forging standard which explicitely defines the tolerances for this element. The studies, which included numerical modelling, infrared measurements and technological tests, consisted in changing the geometry of the tools and that of the forging preform. As a result, the optimum direction for modifications aimed at reducing the mass of the input material was determined. The best of the solutions, making it possible to produce a correct forging in the Jawor Forge operating conditions, were adopted whereby the weight of the preform was reduced by 6.11%. Currently research is underway aimed at the application of the proposed and verified modifications to other flange forgings.

Open access

Z. Gronostajski, M. Hawryluk, J. Jakubik, M. Kaszuba, G. Misiun and P. Sadowski

The paper presents selected examples of solutions and specific user applications associated with the industrial forging processes. Various process specific issues encountered during many years of bilateral collaboration with the forging industry are addressed and analysis methods are presented. As demonstrated in numerous articles and publications, the parameters influencing the die forging process are subject to complicated and mutually related dependencies, which can affect and complicate the methods of analysis. For this reason, researchers, more and more frequently, involve the use of additional support tools such as CAD / CAM / CAE, numerical modelling based on FEM, tool surface scanning methods, physical modelling, advanced microstructural research and dedicated control-measurement systems to validate engaged solutions. The research conducted by the authors included mainly: an analysis of the preform preparation, the impact of the geometry on the forging quality and the heating methods of the material and the tools, analysis of the tribological conditions, as well as an optimization of selected processes in respect of the force parameters, strain and temperature distributions and finally, a weight minimization of the input material. The issues discussed by the authors in the article intend, on the basis of the experience of its creators, to review the issues of the current forging technology and to indicate its possible solutions and development directions.