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The study refers to a comprehensive analysis of the occurrence of defects in forgings constituting elements of window fittings, for which, in the process of their production through precision die forging in a six-impression system at elevated temperatures on a hydraulic hammer, we observe bending of the whole forged element and tilting of the stem (a conical element protruding in a plane perpendicular to the main axis of the forging) in the particular forgings. The investigations included analysis of the technology of precision forging on a hydraulic hammer with an energy of 16 kJ, advanced numerical simulations of the process with the use of a calculation package Forge 3.0 NxT, and dynamic tests of mutual displacement of tools performed by means of a high-speed measurement camera. Preliminary analysis of the process showed that, for forgings with a narrowed dimensional and shape tolerance, produced dynamically on a hammer, the key role is played by elastic deformations as well as the construction of the dies and the geometry of the working impressions, and also the changing tribological conditions. For this reason, multi-variant numerical simulations, including two variants of tools (the standard process and the so-called broken perpendicular flash), were carried out, which made it possible to determine the temperature and forging force distribution in the tools as well as the correctness of the deformed forging material’s flow, the filling of the working impressions, and the defects in the forgings. Next, with the use of a high-speed camera, measurements of the relative displacement of the dies were performed, which showed that a proper change in the construction (geometry) of the tools and the use of locks positively affects the minimization of the displacements and thus increases the quality and dimensional and shape precision. The proposed approach using numerical simulations and dynamic measurements of displacements allows for a relatively quick analysis and the introduction of necessary changes in the technology, including modifications of the construction and geometry, in order to minimize the forging defects. That said, the obtained results did not unequivocally point to one specific optimal solution; therefore, the issue of a total elimination of forging defects is still open and constitutes a scientific challenge. And so, further research and verification studies are required to improve the current forging technology and eliminate forging defects in multiple systems in longer operational periods.

The article presents the results of a complex analysis referring to the possibilities of applying different types of construction of forging dies used on a hydraulic hammer Lasco HO-U 160 in order to select the optimal solution in the aspect of obtaining the required dimension-shape accuracy. The analysis involved the use of the numerical simulation software FORGE 3.0 NxT. 12 different variants were analyzed, of both different tool constructions and detail arrangements on the die (in a quadruple and sixfold system). The effect of the forces as well as the way of material flow and degree of the forging tool seat’s filling were verified. The most ergonomic and technologically justified detail arrangement on the die was described. The results of the numerical simulation analyses were presented with the indication of the pros and cons of the particular solutions. The selected solution of the forging tool construction, implemented in a mass production, was especially discussed to verify of obtained FEM results and improvement actual technology.

The study refers to the application of numerical modeling for the improvement of the currently realized precision forging technology performed on a hammer to produce connecting rod forgings in a triple system through the development of an additional rolling pass to be used before the roughing operation as well as preparation of the charge to be held by the robot’s grippers in order to implement future process robotization. The studies included an analysis of the present forging technology together with the dimension–shape requirements for the forgings, which constituted the basis for the construction and development of a thermo-mechanical numerical model as well as the design of the tool construction with the consideration of the additional rolling pass with the use of the calculation package Forge 3.0 NxT. The following stage of research was the realization of multi-variant numerical simulations of the newly developed forging process with the consideration of robotization, as a result of which the following were obtained: proper filling of the tool impressions (including the roller’s impression) by the deformed material, the temperature distributions for the forging and the tools as well as plastic deformations (considering the thermally activated phenomena), changes in the grain size as well as the forging force and energy courses. The obtained results were verified under industrial conditions and correlated with respect to the forgings obtained in the technology applied so far. The achieved results of technological tests confirmed that the changes introduced into the tool construction and the preform geometry reduced the diameter, and thus also the volume, of the charge as well as provided a possibility of implementing robotization and automatization of the forging process in the future. The obtained results showed that the introduction of an additional rolling blank resulted in a reduction in forging forces and energy by 30% while reducing the hammer blow by one. Attempts to implement robotization into the process were successful and did not adversely affect the geometry or quality of forgings, increasing production efficiency.

The article presents a detailed analysis of the degradation phenomena and mechanisms of selected forging punches made of UNIMAX tool steel. Analyzed punches are used in the manufacture of a constant velocity joint boot forging (CVJB) applied in motorcars with front axle drive. The thorough analysis concerned the punches used in the fourth forging operation after a multi-operational process of forging at elevated temperatures, due to the lowest durability equaling only 4000 forgings. A comparison was made of 5 variants of surface thermo-chemical treatment including 2 types of nitriding (with a low and high potential) and 2 different coatings: CrN and AlCrTiN as well as a punch with and without additional thermo-chemical treatment. The performed complex analysis included a macroscopic analysis combined with scanning of the working surfaces, numerical modeling, microstructural tests, SEM microscopic tests, and microhardness measurements. The obtained results make it possible to select of the optimal variant of thermo-chemical surface treatment which improves the durability of these tools. In particular, the analysis included the manner and areas of wear of the punches as well as their resistance to the particular degradation mechanisms.

In this work, the hot precision forging process was proposed to manufacture the synchronizer ring made of HMn64–8–5–1.5 alloy, and the forming process parameters were optimized. The true stress-strain data of HMn64–8–5–1.5 alloy were obtained through the isothermal compression test. Then, the finite element model of the hot precision forging process of the synchronizer ring was built, and two schemes of the forming process were analyzed and compared. To solve the problems during the hot precision forging process of synchronizer ring, i.e. forging defects, low material utilization and large forming load, a multi-objective optimization method based on grey relational analysis (GRA) and response surface method (RSM) were introduced to optimize the process parameters. As a result, a set of optimal process parameters was determined through the model calculating. Numerical simulation and experiment were carried out to verify the optimal scheme, which was set up based on the obtained optimal process parameters. The results of experimental and numerical simulation have good consistency. The results show that the optimal scheme can ensure product quality, enhance material utilization and reduce forming load.

A theoretical model is presented in the paper for predicting involute profile deflection in hot precision forging of gears. This model is a function of a number of material and processing parameters, including the thermal expansion of the die, thermal contraction of workpiece, elastic expansion of the die during forging, and workpiece recovery after ejection. To improve the accuracy of the hot forged gear tooth, an equation set to define modified involute that is used to design the die tooth has been proposed based on the model. The distribution of deflection along the involute was also predicted using the commercial FE code, PRO-E. The deflection characteristic of the toothed die through the tooth width was analyzed by combining the theoretical method and FEM to investigate the non-uniform deflection. The dimension of the forged gears was measured using a gear measurement machine WGT3000. A close agreement between predicted and measured tooth involute profiles was obtained, which validated the involute deflection prediction model. The measured lead error also verified the model for deflection non-uniformity through the tooth width. The results can provide a guide for die tooth designs to improve the dimensional accuracy of hot forged gear teeth.

Forging simulation offers significant cost and time advantages by providing detailed insight into the forging process before tool selection and process decisions are made on the shop floor. Process data such as material flow, stresses, strains and temperature are readily accessible to a user at any point throughout the simulation process, as well as at any location within the forged part. Potential defects such as laps and under-fill of die cavities can be easily identified and corrected before part production begins. In addition, the influence of the process conditions such as lubrication and pre-form can be easily quantified and assessed. In the present work, hot precision forging process of the straight bevel gear is simulated numerically using finite volume method and computer-aided design/computer-aided engineering technology. The required force for the forging process, as well as the final shape of the bevel gear, is determined through numerical estimation. The simulation results are confirmed through the comparison with the experimental data available in DIN standards. Finally, the pre-form dies, the final die, and the bevel gear are manufactured. It is concluded that this method can be effectively used to optimize the forging process to maximize the mechanical strength, minimize material scrap, and hence reduce the overall cost of manufacture.

Influence of heat treatment on the mechanical properties of the forging was systematically investigated according to tensile test, hardness test and electrical conductivity test. Simultaneously, typical microstructures of the 7A09 aluminum alloy samples subjected to various solution temperatures and aging regimes were characterized by means of Transmission electron microscope (TEM) and Scanning electron microscope (SEM). In the case of the different solution temperatures, the size of precipitations increases with the increase in the solution temperature, which contributes to improving both strength and stress corrosion resistance of the forging. The solution temperature of 465 °C leads to the well comprehensive mechanical properties and the superior stress corrosion resistance of the forging. G.P. zone, η ' phase and η phase are able to precipitate in the matrix of the forging in the case of different aging regimes, such as peak aging, two-stage overaging, two-stage aging, and regression and re-aging. The precipitation phases play an important role in enhancing the mechanical properties of the forging as an obstacle against the dislocation movement.

Precision forging of the helical gear is a complex metal forming process under coupled effects with multi-factors. The various process parameters such as deformation temperature, punch velocity and friction conditions affect the forming process differently, thus the optimization design of process parameters is necessary to obtain a good product. In this paper, an optimization method for the helical gear precision forging is proposed based on the finite element method (FEM) and Taguchi method with multi-objective design. The maximum forging force and the die-fill quality are considered as the optimal objectives. The optimal parameters combination is obtained through S/N analysis and the analysis of variance (ANOVA). It is shown that, for helical gears precision forging, the most significant parameters affecting the maximum forging force and the die-fill quality are deformation temperature and friction coefficient. The verified experimental result agrees with the predictive value well, which demonstrates the effectiveness of the proposed optimization method.

In a re-entrant production system, the throughput of the whole system depends on the capacity of the bottleneck machine. In this study, a new definition of bottleneck is proposed for a precision forging blade shop. The reinforcement learning algorithm is used to optimize the production scheduling to determine the most suitable scheduling scheme, which lays the foundation for bottleneck identification. Subsequently, the bottleneck identification index system was established according to the optimization objective, and the bottleneck identification problem was transformed into a multi-attribute decision-making problem. Finally, a fuzzy neural network is used for training, and the basic scheduling examples of each flow shop are utilized for bottleneck identification and prediction to verify their effectiveness.