Theoretical and Experimental Investigation of Hydromechanical Extrusion Process

Transcription

1 American Journal o Mechanical and Industrial Engineering 017; (1): doi: /j.ajmie Theoretical and Experimental Investigation o Hydromechanical Extrusion Process Olesya Yurevna Agapiva, Sergey Vasilievich Byvaltsev *, Alexander Georgievich Zalazinski Institute o Engineering Science, Ural Branch o the Russian Academy o Sciences, Yekaterinburg, Russia address: agapiva.olesya@yandex.ru (O. Y. Agapiva), s_ikar@mail.ru (S. V. Byvaltsev), zalazinskiy.alexander@yandex.ru (A. G. Zalazinskiy) * Corresponding author To cite this article: Olesya Yurevna Agapiva, Sergey Vasilievich Byvaltsev, Alexander Georgievich Zalazinski. Theoretical and Experimental Investigation o Hydromechanical Extrusion Process. American Journal o Mechanical and Industrial Engineering. Vol., No. 1, 017, pp doi: /j.ajmie Received: Ocber 6, 016; Accepted: November 17, 016; Published: December 9, 016 Abstract: The theoretical and experimental investigation o the process o hydromechanical extrusion (HE) o aluminum alloys Al 5056 was carried out. The aim is determine the optimal parameters o this process. These parameters were determined minimize the extrusion orce and damage acr o a workpiece by using explicit inite elements method. The results were presented in a visual orm and were shown that use o active riction orces reduces the extrusion orce. Statistical processing o the experimental data gave regression equations or deinition the damage acr and the value o the speciic extrusion stress. Keywords: Hydromechanical Extrusion, Computer Simulation, Extrusion Force, Damage Facr 1. Introduction Currently, substantial diiculties appear at some industrial enterprises when high-precision extracting sections made o precious and hard--deorm nonerrous metals and alloys and o ibrous composite materials are processed by pressure (extrusion and drawing). These exacting sections should have high surace smoothness and the given accuracy o sizes over the section, maintain their chemical composition in the limits o their technical speciications at processing, and take the required physicochemical properties [1]. The various methods o solving these problems are known. For example, the extracting sections made o nonerrous metals in nonerrous metallurgy are obtained by hot extrusion o round castings with the ollow-up operations o rolling and drawing. It is reasonable apply these technologies when producing the huge volumes o goods; however, in the case o small-volume production the expenditures are ound be unreasonably high and the process is economically ineicient. The basic disadvantages o the available manuacturing technologies o workpiece extrusion are as ollows: high power inputs or heating the metal; necessity o using several types o complex equipment; high cyclicality o production which is related setting up several types o equipment; possibility o contamination o precision alloys at processing; and occurrence o a butt-end with weight reached thirty percent o workpiece weight. These disadvantages are result in necessity o workpiece section length increasing. However, with increasing o workpiece length the pressure load on the ol rises signiicantly. The methods o backward extrusion, hydroextrusion and extrusion with active inluence o riction orces allow decreasing the pressure load on the ol at comparable draworming and initial workpiece length []. Recently the interest in hydrostatic extrusion as a method or processing hard--deorm materials has been increasing considerably as it was shown that hydrostatically extruded workpiece materials exhibit signiicantly enhanced strength and plastic characteristics [3-6]. Application o high pressure prevents ormation o cracks and enables very high degrees o plastic deormation be achieved at a high rate o deormation [7]. The hydroextrusion process allows receiving highaccuracy sections without workpiece heating and with minimal surace riction. However, the use o this pattern causes signiicant technical diiculties at attempts achieve the semi-continuous deormation process by the workpieceby-workpiece scheme. In addition, because o the

2 18 Olesya Yurevna Agapiva et al.: Theoretical and Experimental Investigation o Hydromechanical Extrusion Process signiicant change in liquid volume under high pressure during deorming the acceleration o the workpiece motion and even its shot at the process end are possible. To prevent these negative phenomena a number o measures substantially complicating the hydroextrusion technology are used. In particular, the hydromechanical extrusion methods combining the high hydrostatic pressure with the mechanical orce are known [8-10]. Their use provides the complete control o the workpiece and product motion during deorming, and, consequently, one can achieve semicontinuous production process by the workpiece-byworkpiece scheme. The series o hydromechanical extrusion schemes is described in [11, 1].. Description o the Hydromechanical Extrusion Concept When carrying out hydromechanical extrusion the workpiece is placed in the container and deormed at the given length, the liquid pressure is released. Ater that, the next workpiece is placed in and is deormed at the given length, etc. [11, 1]. The process is conducted with the application o pressure the back aces o the workpieces that is o 10 15% o the tal deormation orce [13]. The technological eature o the process is the envelopment o the entire workpiece by the actuating medium and the substitution o dry riction o the extruded metal on the container wall and the matrix channel by the liquid riction with the corresponding reduction o the extrusion pressure, which is oten very high. There are also a number o methods o workpiece extrusion with application o active inluence o riction orces at which the deormation non-uniormity and necessary extrusion orce are reduced. Ater the conducted analysis o the contemporary energy eicient methods o workpiece extrusion realization we came the conclusion that the HE method completely meets requirements which were described at the beginning o the article [14]. Taking in consideration the diiculties o realization o HE process there is a necessity in developing the modern system o HE process control [10, 15 and 16]. The mathematical apparatus or modeling the extrusion process is the base o development o the control computer-aided system. The mathematical modeling is considered by the authors o the article as the base or subsequent development o computeraided systems: technological production preparation, design o equipment and a ol, control o a technological process, control o machines and aggregates, and production quality control [17, 18]. 3. Scheme o Development and Research o HE Process Fig. 1 shows the development and research scheme o HE process using sotware. According this scheme the design o a new technological process is not limited the creation o mathematical and computer models o the process. It is also need develop a technology or manuacturing o parts, carry out the engineering analysis and moniring o workpieces damage, develop the appropriate technological equipment subject the limits o the applied equipment, plan the experimental study. To accomplish the tasks the integration o various sotware ols o CAD and CAE systems (SolidWorks and DEFORM D (3D) sotware packages) with the system o computer mathematics MATLAB was carried out. The sotware package SimulaTMP proposed in [19] is taken as a basis or the design system. SimulaTMP is assigned or modeling the processes o metal working by pressure. As a result o the conducted research works the mathematical model o HE has been added in the knowledge base o the sotware system. Figure 1. Pattern o development and research o the HE process with application o sotware ols. 4. Computer Simulation o the HE Process In the study we considered the HE process by varying the draw rom 8 and the coeicient o riction rom or a given diameter o a workpiece 9 mm. At the initial stage o the study the researchers entered the raw data, and then the preliminary calculation o the ol geometry and the calculation o the basic parameters o the

3 American Journal o Mechanical and Industrial Engineering 017; (1): technological process were made within the constraints on the capability o the equipment, on the speciic pressures on the ol, on the heterogeneity o workpiece deormation. Both at the hydromechanical extrusion and at the direct extrusion there is an optimum angle o die conicity. This angle minimizes the required extrusion pressure. The optimum angle is determined according [0]. With development o computer engineering and increasing its productivity it became possible compute the optimal die angle. Ater entering the raw data the minimization o extrusion orce is made taking in account the given initial conditions. Then the initial geometry parameters (die angle) are deined depending on the value o the riction ratio and the drawing value. The results are displayed in a table in a separate window [16]. Below the results o a computer simulation o the HE process are shown. The extrusion pressure depends not only on the die angles but also on the value o the riction ratio. Fig. a shows that with increase o the riction ratio the extrusion pressure also increases. In the case o optimum design o the die the extrusion orce as a unction o the drawing value at the constant initial diameter o a workpiece is shown in Fig. b. Ater the initial ol geometry is determined in accordance with the scheme shown in Fig. 3, a three-dimensional parametric model o production oling and a workpiece is created and transmitted in the ormat *.XLS in the CAD package o Solid Works. The researcher has a possibility modiy the model (Fig. 3). 5. The Results o Computer Simulation Figure 3. Three-dimensional model o oling or hydromechanical extrusion. Pв/ t =0.4 =0.3 =0. =0.1 a , b Figure. Extrusion orce as a unction o the riction value at dierent draws (a); extrusion orce as a unction o the die angle at dierent riction ratios (b). 1 - mouthpiece; - deorming die; 3 - ram case; 4 - punch; 5 - container; 6 - sleeve; 7 - botm spacing ring. On the base o the raw data as a result o determining the extrusion orce and the optimum die angle the calculation o the ol sizes is carried out provide the necessary rigidity o the construction. Ater the ol model is edited through data export and import the parametric model (coniguration details data) is transerred in the ormat *.igs (*.stl) DeormD (3D) o CAE package simulation o the HE process. Then the engineering analysis o the data obtained by computer simulation is carried out. In the package DeormD (3D) the necessary calculations using the inite elements method were made (Fig. 4). The result o computer simulation o the HE process in the package DEFORM D is prediction o the illing o the deormation zone and the emergence o the deects, determining o necessary deormation orce, deormation energy, stress-strain state, the low velocity o the workpiece material and the lubricant layer. The deorming orce was determined depending on the size o the workpiece, its shape, and riction ratio and material properties. Furthermore, by computer modeling the workpiece parameters such as the

4 0 Olesya Yurevna Agapiva et al.: Theoretical and Experimental Investigation o Hydromechanical Extrusion Process cumulative strain, the stress, the direction o the workpiece iber, the possibility o destruction o the workpiece and ol wear were determined. Fig. 4a shows a 3D model o the hydromechanical extrusion. Between the workpiece and the oling there is a layer o lubricant. It is evident that during the deormation process the lubricating layer advances the workpiece that is possible due active action o riction orces. Fig. 4b shows the distribution o deormation intensities over the longitudinal section o the workpiece. It was ound that the maximum intensity o deormation (indicated by the arrow in the igure) equal is observed in the center o deormation on the axis o symmetry o the workpiece. Figure 4c shows the distribution o the average normal stresses over the longitudinal section o the workpiece. It is obvious that in the center o deormation the compressive stresses dominate. The minimum o the average normal stress (indicated by the arrow in the igure) equal -95,4 MPa is observed on the axis o symmetry o the workpiece in the area disposed in the working cone o the die. Figure 4d shows the distribution o stress intensity over the longitudinal section o the workpiece. In the package DEFORM the computational simulation o the studied process, deining the stresses and the deormations o the junction points o the inite element grid, determination o the extrusion orce at each iteration step were made. On the second stage the ol stress analysis is carried out (Fig. 5). The researcher also has a possibility interact with the package DEFORM or run-time correction o the computation progress. a - model o hydromechanical extrusion; b - distribution o eective strain; c - distribution o mean stresses; d - distribution o eective stresses. Figure 4. The results o computer simulation in the package DeormD. Figure 5 shows the distribution o equivalent stresses over the longitudinal section o the ol and the workpiece, the maximum equal 330 MPa is revealed in zone I. The engineering analysis o the HE process allows deining the optimum conditions o deormation by minimizing the extrusion orce and the deormation inhomogeneity. Prediction o material workpiece damage allows reveal the possible deects on the design stage and generate the conditions or their prevention. The ol strength calculation provides a possibility o selection the material or ol production.

5 American Journal o Mechanical and Industrial Engineering 017; (1): shown (Table 1). Table 1. The scheme and the results o the investigation o the HE process. Figure 5. The results o ol analysis in the package DeormD (3D). According the results o computer simulation the drawings or ol production are developed. 6. Experimental Investigation Cylindrical workpieces o aluminum alloy Al5056 with diameter o 9 mm and length o mm were extruded in all experiments. The deinition o optimum technological parameters o the HE process on the condition o minimum damage and minimum extrusion orce was the aim o the experimental investigation. Below the scheme and the results o the experimental investigation o the HE process are Draw µ Friction ratio, Ψ Process value q, MPa ,1 Pх10 4, N,71 4, 5, 6,37 ω 0,308 0,93 0,17 0,175 q, MPa , Pх10 4, N,14 4,3 5,45 6,61 ω 0,3 0,31 0,05 0,179 q, MPa ,3 Pх10 4, N,46 4,36 5,75 6,67 ω 0,71 0,184 0,17 0,39 q, MPa ,4 Pх10 4, N,68 4,53 5,7 6,8 ω 0,36 0,164 0,1 0,176 According the results o the calculation experiment we chose the mathematical model or deinition the damage acr (1) q q q D b b b b b b p p p = 1 + µ µ + 5µ + 6 where D damage acr (Cockcrot-Latham damage model); µ - draw; q p- ratio o the lateral pressure the stress o extrusion; b1, b, b3, b4, b5, b6- constant coeicients. (1) Figure 6. Speciic extrusion stress (a) and damage acr q p. D (b) as unctions o the draw µ and the ratio o the lateral pressure the stress o extrusion To determine the relationship (1) we carried out the regression analysis o the experiment results shown in Table 1 and Figure 6a. Statistical processing o the experimental data using the computer mathematics system MATLAB gave a possibility get the ollowing regression equation: D q q q p p p = 1, , 087µ 5, 789 0, 039µ 0, 006µ + 7, 071 () The analysis o the simulation results allowed recognizing the optimal parameters o the HE process on the condition o minimizing the damage acr. With the draw value µ = and the ratio o the lateral pressure the stress o extrusion

6 Olesya Yurevna Agapiva et al.: Theoretical and Experimental Investigation o Hydromechanical Extrusion Process equal q p = 0, 4 the Cockcrot-Latham damage acr equals D = Since at production o rod pieces there is a limitation o the draw µ 4, the optimal process parameters o the hydromechanical extrusion on the condition o minimizing the damage acr are q p = 0, 4. Thus, the value o the damage acr increases rom D = D = when the draw value changes rom 4 6. The urther increase o the draw leads reduction o the damage acr the values D = and D = or µ = 7 and µ = 8 respectively. The optimal value o the ratio o the lateral pressure the extrusion stress remains constant and equal q p = 0, 4. Based on the results obtained at simulation o the HE process o the aluminum alloy we chose the mathematical model (3) describe the value o the speciic extrusion stress. p q q a a µ a a µ a µ σ = + + p + p + (3) where extrusion stress; σ - initial value o yield stress; µ - draw; q - pressure lateral side o the workpiece (lateral pressure); a1, a, a3, a4, a5- constant coeicients. Using the computer mathematics system MATLAB we ormed the dependence o the speciic extrusion stress p σ on the draw µ and the ratio o the lateral pressure the extrusion stress q p (Fig. 6b). Statistical processing o the experimental data using the computer mathematics system MATLAB allowed receiving the ollowing regression equation: p q q 0, ,3594 1,3655 0,356 0, 038 σ = + µ + p + µ p µ (4) p According the simulation results it can be concluded that with draw increase the speciic extrusion stress increases rom It is recommended use a draw speciied rom the permissible value o the pressure on the punch. Thus, when p / σ =.5 and q p =0,4 the maximum per draw equals µ = 7. The proposed method can be used study the process o the hydromechanical extrusion o hard--deorm metal materials. 7. Conclusion The methodic o the computer-aided engineering analysis and the design o a new technological process such as the HE process was worked out. In the developed sotware system as a result o the integration o several specialized packages the system o computer-aided design o technology and equipment or implementation o the high-perormance HE process producing the simulation o the process, the calculation o the basic power parameters, the test o strength and the development o assembly drawings and parts oling was created. The analysis o the results o HE process simulation is presented in a visual orm and shows that use o active riction orces reduces the extrusion orce. When developing the sotware the problem o introducing a new technological process in the existing sotware environment was solved. The developed sotware system can be widely used in development o new technologies and optimization o existing technologies as well as a study aid or construction o complex integrated sotware systems. Reerences [1] Zalazynskii, A. G. Plastic Deorming o Structurally Inhomogeneous Materials // Yekaterinburg: UrO RAN, 000, 49 p. [] Danilin, A. V. Investigation o the Stress-Strain State and the Particularities o the Metal Flow during Direct Pressing and SPAT Pressing o Hard--Deorm Alloys// Russian Journal o Ferrous Metals, 004, No. 5, p.45. [3] Kolmogorov, G. L., Mikhailov, V. G., Barcov, Yu. A., Karlinski, V. A. Hydropressing o Hard--Deorm Reracry Metals and Alloys // Metallurgy, Moscow, 1991, 14 p. [4] Pachla, W., Kulczyk, M., Sus-Ryszkowska, M., Mazur, A., Kurzydlowski, K. J. J. Mater. Process. Technol., 05 (008), p [5] Zherebtsov, S., Mazur, A., Salishchev. G., Lojkowski, W. Mater. Sci. Eng. A, 485 (008), p. 39. [6] Zherebtsov, S., Salishchev, G., Łojkowski, W. Strengthening o a Ti 6Al 4V titanium alloy by means o hydrostatic extrusion and other methods, Materials Science and Engineering: A, Volume 515, Issues 1, 5 July 009, Pages [7] Bridgeman, P. W. Studies in large plastic low and racture, MC Graw-Hill, New-York, 195. [8] Beresnev, B. I., Gaivoronskii, A. T., Zamaraev, V. K., and others. Hydraulic Forging // Yekaterinburg: Inst. Prikl. Mekh. UrO RAN, p. [9] Kolpashnikov, A. I., Vyalov, V. A. Hydraulic Forging o Metals // Moscow: Metallurgiya, [10] Zalazinskii, A. G., Byvaltsev, S. V., Zalazinskaya, E. A., Agapiva O. U. Modelling o process o hydromechanical extrusion // Electronic Journal "Investigated in Russia", 010, no. 13, p [11] Agapiva, O. U., Byvaltsev, S. V., Zalazinskii, A. G. Improvement o hydromechanical extrusion o non-errous metals // Russion Journal o Non-errous Metals, 011, no. 5 (4), p [1] Agapiva, O. U., Byvaltsev, S. V., Zalazinskii, A. G. Features o processes o direct and hydromechanical extrusion billets // Forging and Stamping Production. Material Working by Pressure, 013, no. 10, p [13] Agapiva, O. U., Byvaltsev, S. V., Zalazinskii, A. G. Determination o rheological properties o plasparain or simulation o metal orming processes // Handbook. An Engineering journal with appendix, 01, no. 1 (189), p. 3-5.

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