Cold forging of a hollow flanged part by an unconventional extrusion method

This paper presents a numerical analysis of a new cold forming process for a hollow part with an external flange. The following techniques were used: forward extrusion, an unconventional method of extrusion with a moving sleeve, and upsetting in a tapered die cavity. The billet (42CrMo4 steel tube) was formed at ambient temperature. The study aimed to investigate the proposed method in terms of forged part accuracy. The following are examined and discussed: material flow, process force parameters in relation to tool strength, energy consumption of individual operations, as well as the distributions of strains, stresses, temperature and Cockcroft-Latham integrals in the produced part. The study has confirmed that hollow forged parts with external flanges of relatively large diameters and heights can be cold formed in several operations using different techniques.

Application of Numerical Simulation and Physical Modeling for Verifying a Cold Forging Process for Rotary Sleeves

This paper presents the modeling of a cold forging process for a rotary sleeve. The process of forging a EN 42CrMo4 steel part was first modeled numerically by the finite element method using simulation software DEFORM 3D ver. 11.0. After that, the developed forging process was verified by experimental tests carried out in laboratory conditions with the use of 1:2 scale tools and a material model of aluminum alloy EN AW-6060. Finite element method (FEM) results demonstrated that rotary sleeves could be formed from tubes by cold forging. Results of the experimental tests showed, however, that the material inside the hole of the work piece might not adhere to the surface of the sizing pin. Distributions of strain and stress during the forging process are determined. Geometrical parameters of forged parts obtained in experimental tests are compliant with the dimensions of forged parts simulated by FEM. In addition, experimental forces of the forging process show a high agreement with the forces obtained in FEM simulations.

Numerical Analysis of Friction Effects on Temperature and Phases within Forged Ti-6Al-4V Alloy Aeroengine Drum

Friction conditions significantly impact the temperature and phases of titanium forged parts, further directly affecting the microstructures and mechanical properties of final parts. In this paper, a 2D simplified finite element (FE) model combined with phase transition equations is developed to simulate a Ti-6Al-4V drum forging procedure. Then, friction effects on the temperature and phases of the forged drum are numerically analyzed and verified by experiments. The simulated results indicate that a reasonable range of friction factor is needed to obtain a relatively homogenous temperature distribution within the forged drum. Moreover, unlike its small influence on the α + β phase, improving friction obviously decreases the general levels of temperature and β phase and increases the homogeneities of α and β phases within the forged drum, which are associated with cooling rates and the heating effects of friction and deformation.

Numerical Analysis of Friction Conditions on Temperature and Phases Within Forged Ti-6Al-4V Aeroengine Drum

Friction conditions significantly impact the temperature and phases of titanium forged parts, further directly affecting the microstructures and mechanical properties of final parts. In this paper, a 2D simplified FE model combined with phase transition equations is developed to simulate Ti-6Al-4V drum forging procedure. Then, friction effects on the temperature and phases of the forged drum are numerically analyzed and verified by experiments. Results indicate that unlike little influence on α+β phase, improving friction obviously decreases the general levels of temperature and β phase and increases the homogeneities of α and β phases within the forged drum, which are associated with cooling rates and the heating effects of friction and deformation.

Investigation of Forging Performance for AA6082

6XXX series aluminum alloys are generally excellent alternatives to steels for many forged parts in aerospace and automotive industries. In this study, the forging performance of the 6082 aluminum alloy is investigated in order to replace the existing material for forged steel parts. The effect of artificial aging of the alloy on the microstructure and mechanical properties is studied. Optimum aging conditions are determined. Results reveal that AA6082 could be a good replacement for applications where shock and vibrational loads exist. The rod end part currently manufactured from AISI1045 can be replaced by AA6082 without any design changes. The major drawback is that the cold forging of the aged alloy is poor due to its brittle nature and crack initiations. Therefore, warm or hot forging is recommended to overcome the poor forgeability.

Case Study of the Effect of Precoating on the Decarburization of the Surface Layer of Forged Parts during the Hot Die Forging Process

This paper aims to evaluate the effect of pre-coating of forged parts on decarburization in the die forging process. The studies consisted of three stages. In the first instance, different coatings were tested under laboratory conditions by heating steel samples to the temperature of 1200 °C for over five minutes to model the preheating conditions of the induction. Next, testing continued in a commercial forging stand where we tested the effects of different coatings on the rods decarburization during the induction heating process, usually performed before forging. Once completed testing, the measurements and observations of the decarbonized layer were made. The third stage involved analysis of the decarburization of the forged parts after forging. The forged parts were made using precoating of pre-forging elements; pieces cut off a metal rod. Based on tests results, the possibility of using this solution in the technique of industrial hot forging was evaluated. The results of laboratory tests have confirmed that lubrication of metal pieces is sufficient, as well as proved it to be effective in reducing decarburization of the surface layer. Research works conducted in an induction heater showed differences in decarburization depending on a substance and concentration of lubricants that were used. These differences become more apparent when observing the surface layer of the forged parts. Results indicate that decarburization may be reduced to a minimum when we use Bonderite product in a concentration of 66% and 50%. Another lubricant, Berulit 913, may also be used. However, due to burning graphite in high temperatures, reduction of decarburization goes only as far as half of the thickness of the decarbonized layer. Condursal has no significant effect; nevertheless, it protects over the induction heating stage.

Experience with the Introduction of SAFT Testing in Volume Production of Large Forged Parts

Large rotor forged parts, which are usually one of the most critical components in land-based turbines and generators for power generation, require a complex volumetric test for a sufficient service life. This is usually performed manually or automatically with ultrasound. New requirements, designs and materials require more sensitive testing. This can be achieved by SAFT, also called ultrasound computer tomography. SAFT is based on the Synthetic Aperture Radar (SAR) and has been further developed by several universities. The introduction of SAFT in the volume production of large forged parts was achieved by the introduction of the quantitative SAFT developed by Siemens, also called AVG or DGS-SAFT, which allows an evaluation of each voxel in units of a replacement reflector, and by an acceleration that allows the reconstruction of the complete volume of a large forged component, which could be obtained when the SAFT test was introduced into volume production. The challenges for level 2/3 reviewers are discussed, such as volume-corrected display of results, handling of large amounts of data, focusing of displays, amplitude representation in units of a replacement reflector and handling of the software. Furthermore, it is shown how displays are represented by SAFT, how the detection limit can be determined in the case of quantitative SAFT, and which artifacts can occur during series testing with SAFT.

Case Study of the Effect of Precoating on the Decarburization of the Surface Layer of Forged Parts during the Hot Die Forging Process

Based on tests results, the possibility of using this solution in the technique of industrial hot forging was evaluated. The results of laboratory tests have confirmed that lubrication of metal pieces is sufficient as well as proved it to be effective in reducing decarburization of the surface layer. Research works conducted in an induction heater showed differences in decarburization depending on a substance and concentration of lubricants that were used. These differences become more apparent when observing the surface layer of the forged parts. Results indicate that decarburization may be reduced to a minimum when we use Bonderite product in a concentration of 66% and 50%. Another lubricant, Berulit 913, may also be used. However, due to burning graphite in high temperatures, reduction of decarburization goes only as far as half of the thickness of the decarbonized layer. Condursal has no significant effect; nevertheless, it protects over the induction heating stage.