THE INFLUENCE OF LUBRICANT SYSTEM IN DEEP DRAWING WALLS THICKNESS

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1 Nonconventional Technologies Review Romania, December, Romanian Association o Nonconventional Technologies THE INFLUENCE OF LUBRICANT SYSTEM IN DEEP DRAWING WALLS THICKNESS Alin Pop 1, Ioan Mihăilă 2, Ioan Radu 3 1 University o Oradea, alinpop23@yahoo.com 2 University o Oradea, 3 University o Oradea, ABSTRACT: Deep drawing process depends on the right choice o the input parameters. The coeicient o riction between the active elements and the blank is a very important actor in getting proper parts in terms o quality. This paper presents the inluence o dierent lubrication systems on aecting the way that the thickness o deep drawing part varies. The paper analyzes three types o lubrication. The experimental results are obtained or deep drawing parts made without any lubrication, with lubricant and with ilm lubricant. KEY WORDS: deep drawing, riction coeicient, lubricant 1. INTRODUCTION Deep drawing is one o the most common processes in metal sheet deormation. Deep drawing is the transormation o a plan blank in to a cylindrical, parallelepiped or complex shape (ig 1). Research in this area is vast and the literature can proo this. Approach to drawing applications range rom the study o the inluence o parameters deep drawing to applications that can get new ways to optimize the process [1], [2], [3]. aect the rictional orces between the active elements. s may also be inluenced by temperature tool. s play an important role in the process o drawing, reducing the coeicient o riction thus having the role to contribute to the production o quality parts. A good lubricant will decrease ailure rate. In the literature there are two models o riction that can describe riction conditions during the deep drawing process [10]. In igure 2 is shown the relationship between contact pressure and rictional shear stress. τ = μ p (1) Where τ =rictional shear stress, μ - coeicient o riction and p= normal pressure. Figure 1. Schematic representation o the deep drawing process [ 7] The process o deep drawing is characterized by a very complicated strain, aected by the ollowing parameters[4]: material properties; geometry o the active elements; shape o the blank; speed o the punch; coeicient o riction. The quality o deep drawing parts is inluenced by certain variables that can be controlled [11]. The low o material during the deep drawing process depends on the type o lubricant used, witch can Figure 2. Relationship between contact pressure and rictional shear stress [10] In equation 2, i m=0 we have no riction, i m=1 we have a sticking riction condition. 94

2 σ τ = σ = m = mk (2) 3 Where =riction actor, m=shear actor, k=shear strength and σ =low stress. The riction is one o the most important parameters aecting the orce required to low the material and the orming process. The coeicient o riction has either positive or negative role in the drawing o the material. The coeicient o riction between the active elements and elements is a parameter that can positively inluence the drawing i correct. An excessive riction lead to deects such as cracks and riction coeicient too low can cause ripple phenomenon on the lange piece. 2. LUBRIFICANT TYPES USED IN EXPERIMENTS The quality o deep drawing part is determined by the surace roughness and the wall thickness proile [7]. Figure 4. Deep drawing part obtained with lubricant system Deep drawing process parameters used in the study are presented in table 1. Table 1. Deep drawing parameter process Parameters Punch radius Die radius Blank holder orce Value 3 mm 6.5 mm 9000 N Without lubrication The study analyzes the deep drawing part rom the thickness point o view. The part measurement was made with the coordinate measuring machine.[5][6] It s been analyzed 31 points along the part proile, the points density is higher and radius area (ig. 5). Figure 3. Deep drawing part obtained with ilm system In research were analyzed three types o riction between the die active elements and the blank: no items to reduce the coeicient o riction; lubricant luberstone 4211 (ig.4); ilm (ig. 3). Luberstone 4211 was created to improve the quality o parts obtained by drawing. It can also be used as a lubricant, in the cold working aqueous galvanized pipes. Luberstone 4211 can be applied manually. The other input parameters in the process o deep drawing, punch radius, die radius and the blank holder orce are considered ixed. Figure 5. Measurement points locations For punch radius 3 mm and die radius 6.5 mm were obtained ollowing experimental data (table 2): 95

3 Table 2. Values o material thickness measured rom the center to the outside parts Without lubrication Regions The bottom part Connecting the wall to the bottom piece Side wall Connecting the wall to the lange Flange 3. EXPERIMENTAL DATA ANALYSIS The study area was divided into 4 typical zones or a deep drawing part. The inluence o this parameter on the variation in thickness o the workpiece can be viewed using the graph in igure Figure 6. Thickness variation o the deep drawing piece using three lubricate systems 96

4 Initial thickness o the blank is mm and the diameter is 188 mm. A signiicant thinning appears in the bottom piece and sidewall connection and a thickening in the lange material. In order to make the necessary observations and conclusions the chart rom igure 6 was divided into our dierent areas such: or the lower part piece (ig.7): without lubicant lubricant ilm Figure 7. Thickness variation o the bottom part according to the selected type o lubricant According to the chart, it can be seen that in the experiments which have not used any lubricant, the thinning o the piece is most pronounced, very close to these values but slightly higher is the thickness variation or the experiments with lubricant. When using ilm as a means o reducing riction between the active elements and elements were obtained best results. For the connection o the bottom part to the side wall the graph values are showed in ig. 8: Figure 8. Thickness variation o the radius o the lower part and the side wall connection based on the selected type o lubricating As in the irst area studied the use o ilm is the best choice to reduce the coeicient o riction, which would lead to a greater thickness o this zone. It can be seen that the thickness piece or the ilm obtained is relatively close to that which is obtained by the blank with grease lubrication. For the sidewall (ig.9) Figure 9. Thickness variation sidewall deep drawing part In the upper part o the sidewall thickness begins to exceed mm standard thickness o the blank, but only or the part obtained using ilm. The connection between lange and the side wall(ig 10) Figure 10. Thickness variation o the connection bettwen lange and the side wall In the area o connection between bottom part and the side wall it s indicate that the part thickness is higher to avoid tears. In the lange deep drawing part area can appear wrinkling or higher thickness, so the use o ilm can lead to major deects as wrinkling. This can happen when the blank holder orce is to small. The highest value o the thickness is mm. 97

5 Standard deviation Without libricant Figure 11. Standard deviation The standard deviation or each lubrication system is shown in igure 11, and the minimum thickness values are shown in igure Without libricant Figure 12. Minimum thickness The minim value or the thinning is obtained or the deep drawing parts with no lubricant. It can be seen that or ilm as system lubricant the thickness is higher than the other. 4. CONCLUSION The coeicient o riction between active elements and the blank is determined by the lubrication system used. Were used three blank lubrication systems. The walls proile thickness was measured with the coordinate measuring machine in 31 points. For a better understanding o thickness dierent between the three lubrication systems, the deep drawing part was split in our parts. The biggest thinning it was obtained when it wasn t use any lubricant, and the smallest thinning it was obtained or ilm as lubricant system. In terms o the experimental data we can conclude that the use o ilm is the best option to analyze thinning material. 5. REFERENCE 1. M. El Sherbiny, H. Zein, M. Abd-Rabou, M. El shazly., Thinning and residual stresses o sheet metal in the deep, Materials and Design , (2014). 2. Jurkovic, Z. and Jurkovic, M., Modelling and optimization o the tool geometry or deep drawing o sheet metal, Metalurgija, Vol. 39, no. 4, pp , (2000). 3. Choi, J. C., C. Kim, Y. Choi, J. H. Kim and J. H. Park, An Integrated Design and CAPP System or Deep Drawing or Blanking Products, Int. J. Adv. Manu. Technol., , (2000) 4. Banabic, D., Sheet Metal Forming Processes. Constitutive modelling and numerical simulation, Springer, Heidelberg, Berlin, (2010). 5. Yongjun Zhang- Measurement o industrial sheet metal parts with cad-design data and nonmetric image sequence 6. Moshe Berger, Eyal Zussman, On-Line Thinning Measurement in the Deep Drawing Process, Journal o Manuacturing Science and Engineering, (2002). 7. Y.M. Shashidhara and S.R. Jayaram, Deep drawing o 304 L Steel Sheet using Vegetable oils as, International Journal o Advancements in Research & Technology, Volume 1, Issue7, December, (2012). 8. A.,X., Carcel, Evaluation o vegetable oils as pre-lube oils or stamping, Materials Design Vol.26, pp , (2005). 9. K., R., Gilmour, et. al., The inluence o Thickness on Friction Coeicients During Slow Speed Deep Drawing Operations, ASME J. Tribol, Vol.124, pp , (2002). 10. Soumya Subramonian, Evaluation o lubricants or stamping deep drawing quality sheet metal in industrial environment - Thesis Presented in Partial Fulillment o the Requirements or the Degree Master o Science in the Graduate School o The Ohio State University 11. Conry, T. F., Odell, E.I., and Davis, W.J., Optimization o die proiles or deep drawing, Journal o mechanical design, Vol. 102, no. 3, pp , (1980). 12. Eriksen, M., The inluence o die geometry on tool wear in deep drawing, Vol. 207, no. 2, pp , (1997). 13. Gharib, H., Wii, A. S., Younan, M. and Nasse, A., An analytical incremental model or the analysis o the cup drawing, Journal o Achievements in Materials and Manuacturing Engineering, Vol. 17, no. 1-2, pp , (2006). 98