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Forging of shafts, discs and rings from blanks with inhomogeneous temperature field
Abstract
The aim of this work is to determine the effect of temperature mode of forging of details such as shafts, discs and rings on the parameters of stress-strain state (SSS) of the workpiece in the process of broaching, upsetting, and expansion. Methods of forging of rings, discs and shafts from billet with non-uniform temperature field were proposed. The processes of forging, which showed the effectiveness of a SSS control of the workpiece temperature field were studied. In the process of forging of rings with the use of a smooth mandrel and a flat die is possible to obtain profiled rings only due to the inhomogeneous temperature field in the workpiece. In the process of forging of the disks by upsetting, also using a flat die, it is possible to obtain forgings of complex shape.
... However, the experiment result revealed that the use of When conducting experiments on drawing workpieces without pressing the flange, the thicknesses of the obtained parts were also measured [30,34,35]. To do this, we used a micrometer thickness gauge with a measuring range of 0-25 mm and a division value of 0.01 mm to determine the strain mechanism and to formulate recommendations on the application of this process to production. ...
The development of a method for drawing cylindrical parts without pressing the workpiece flange, which allows reducing the cost of production due to the use of dies without a fit ring and single-acting presses. The performed research revealed that this method results in obtaining cylindrical parts with drawing ratios typical for pressing drawing. In this case, the different thickness of the finished product is several times less compared with the same type of semi-finished products obtained by drawing with a fit ring. Steel, aluminum and copper workpieces were researched. The best results were shown by more plastic materials. This method is not applicable for materials with the less than 0.25 mm thickness.
... Relative depth of the concave facets of the workpiece (d/D) varied in the range of 0.75; 0.80; 0.85. Material of the workpiece is steel 34HNM, initial temperature for conducting the process is 1.200 °C, friction coefficient is 0.35, the grid is composed of 60,000 elements, the motion speed of a deforming tool is 20 mm/s [21][22][23]. In order to determine an indicator of the stressed state in the axial zone, we marked a reference point in the middle of the height of the workpiece in which we monitored the mean stresses and the intensity of stresses. ...
We propose a forging method for forgings, which implies the upsetting of workpieces with concave facets. A procedure for the theoretical research has been devised aimed at studying the mechanism of closure of artificial axial defects in workpieces. The study was performed based on a finite element method. The key examined parameter was the depth of the concave facets in a workpiece. This parameter varied in the range 0.75; 0.85; and 0.80. The angle of the concave facets was 120°. The results of the theoretical study are the following distributions: deformations, temperatures, and stresses in the body of a workpiece in the process of upsetting the workpieces with concave facets. Based on these parameters, we established an indicator of the stressed state in the axial zone of the workpiece. In order to verify the theoretical results obtained, a procedure for experimental research has been developed. The study was performed using the lead and steel workpieces. The results of the theoretical study allowed us to establish that the effective depth of the concave facets is the ratio of diameters of protrusions and ledges equal to 0.85. At this ratio there occurs the intensive closure of an axial defect. This is due to the high level of compressive stresses when upsetting the workpieces with concave facets. We have established the effective degree of deformation at which the intensive closure of defects takes place. Also established are the distributions of deformations for the cross-section and height of the workpiece, as well as a change in the indicator of the stressed state in the process of upsetting workpieces with concave facets. The closure of axial defects has been confirmed by experimental study using lead and steel samples. The new technique for upsetting workpieces with concave facets has been implemented. The results of ultrasonic testing have allowed us to establish that the obtained parts do not have internal defects, which exceed the requirements of the European standard SEP 1921. Our research has led to the conclusion of the high efficiency of the proposed new method for upsetting workpieces with concave facets, which implies the improvement of quality of the axial zone of large forgings when using a given technique. © O. Markov, V. Zlygoriev, O. Gerasimenko, N. Hrudkina, S. Shevtsov, 2018.
The paper presents the results of development and investigation of the new method of forging heavy long-length billets from steels and alloys with intensification of shear deformation and with the use of standard anvils. Additional shear deformation is obtained due to mutual displacement of the anvils. To assess the efficiency and feasibility of the practical use of the new forging method, a group of criteria was chosen. Computer simulation by the finite element method of the new forging scheme has shown its high efficiency in comparison with the conventional forging schemes from the point of view of the chosen group of criteria. Verification of computer simulation is carried out on blanks from D16 aluminium alloy (State Standard GOST 21488-97) on a hydraulic press with a nominal force of 900 kN. To compare the deformation fields from computer and physical modeling, the digital image correlation method was used.
This paper presents the various ways of forging large forged pieces such as shafts, plates, and discs. A finite element method was used to simulate open die forging processes such as forging by flat dies with a slant, forging by staged dies, and upsetting of profiled workpiece. The parameters of the stress strain state of the billet in these processes were determined, along with the rational parameters for forging plates by flat dies with slant such as tool size and mechanical modes. The optimal die step dimension and mechanical regime for forging shafts by staged tools was determined. Also, the rational geometric parameters of the workpiece for forging discs by upsetting were determined. For these forging schemes, a simulation was done of the microstructure evolution in forgings obtained by traditional technology and new proposed technology. The paper shows the advantages of new forging schemes which provide a uniform distribution of grain size in the obtained billets.