Comparative study of wall thickness change at deep drawing of box-shaped product using flat restriction bars

In the paper the deep-drawing method using flat restriction bars to restrict plastic flow of sheet material at straight parts of drawing die by increasing of resistance to friction between a blankholder, a die and a blank is presented. Mentioned bars provide enough radial stresses in the drawpiece’s flange to prevent the excessive material flow into the drawing die. Parameters of the deep drawing process such as the blankholder force and the restriction bars’ normal force, given by filling pressure of gas springs were tested and adjusted to deep drawing of a bathtub model. The wall thickness change was measured by the dial gauge and by photogrammetric method using 3D optical system ARGUS. The experiments were done using the cold rolled steel sheet for enameling KOSMALT 240 with thickness of 0.6 mm. The results of measurements of bathtub wall thickness reduction by using both considered methods showed the same tendency, but there is a difference in values of thickness reduction. The measurements based on the non-contact 3D op-tical system ARGUS gave the lower values of wall thickness reduction at critical areas of the bathtub model equals of 10.6-11.7%, compared to ones measured by the dial gauge.

Full text (pdf)

1. Eary D.F., Reed E.A.: Techniques of pressworking sheet metal. Prentice-Hall Inc., Englewood Cliffs, New Yersey 1974.
2. Pollák L.: Stamping dies design. ALFA, Bratislava 1978.
3. Pahl K.J.: New developments in multi-point die-cushion technology. J. Mat. Proc. Technol., 71 (1997), 168-173.
4. Altan T., Penter L.: Application of modern cushion systems to improve quality and productivity in sheet metal forming. Proc. CIRP Conf. Machine-Process Interactions, Vancouver 2010.
5. Doege E., Elend L-E.: Design and application of pliable blank holder systems for the optimization of process conditions in sheet metal forming. J. Mat. Proc. Technol., 111 (2001), 182-187.
6. Trzepieciński T.: Advances in sheet metal forming technologies. Zeszyty Naukowe Politechniki Rzeszowskiej Mechanika, 84/4 (2012), 59-70.
7. Pollák L.: Anisotropy and drawability of steel sheet. Alfa, Bratislava 1978.
8. ARGUS User’s Guide, 2011.
9. Frącz W., Stachowicz F., Trzepieciński T.: Investigations of thickness distribution in hole expanding of thin steel sheets. Arch. Civ. Mech. Eng., 12 (2012), 273-289.
10. Frącz W., Pieja T., Stachowicz F.: Aspekty weryfikacji i optymalizacji symulacji numerycznych procesu tłoczenia blach z wykorzystaniem systemu fotogrametrycznego. Wydaw. AKAPIT, Kraków 2012, 187-200.
11. Frącz W., Stachowicz F., Pieja T.: Aspects of verification and optimization of sheet metal numerical simulations process using the photogrammetric system. Acta Metall. Slovaca, 19 (2013), 51-59.
12. Slota J., Jurčišin M., Gajdoš I., Spišák E.: The sensitivity of a photogrammetric method in formability analysis. Acta Mech. Automatica, 7 (2013), 117-123.
13. Hudák J., Tomáš M.: Experimental drawing die with plastic flow regulation for complicated pressings shapes. Acta Mech. Slovaca, (2008), 163-168.
14. Hudák J., Tomáš M.: Intensification of deep drawing process for production of square cups. Kovárenství, 44 (2012), 61-64.