Theoretical Investigation of the Bending Process of the Pre-Strained Metal Sheet

Abstract

During the bending operation of the thin sheet materials by the punch with the near-to-zero radius the special technological operation should be carried out. It means that the metal sheet obtained a certain thinning value, which is usually done in the form of the channel-concentrator or groove by pre-drawing operation in a cold state. It follows to the pre-straining and strengthening of the material. The authors investigated the strain hardened sheet's area after roll forming process theoretically, and obtained the strain-stress distribution inside the sheet during the bending operation. It was found out that the increase of the prior deformation during pre-straining in the bend layer follows to the increase of the radial and tangential stresses and displacement of the neutral axis inside the blank during bending operation. As a result, the bending moment changes its values depends on the punch radius and strain hardening.

Testing the Cross-Sectional Microhardness in Sheets with A 0.08% Carbon Concentration

“…Some papers suggest that material properties may change through thickness [1][2][3][4][5][6][7][8][9][10][11][12][13]. Material properties are often associated with multiple indicators [17][18][19][20][21][22]; however, assuming that the strain is stable and homogeneous by thickness, one can find material-specific means.…”

Investigation of Uneven Properties of Stainless Steel 12Kh18N10T Depending on the Thickness of the Sheet

“…The variable values of hardness or strength on the section can be the result of process peculiarities which is shown in paper [11] for steel 50. However, in most cases the variable properties depending on thickness are caused by residual stresses at prior strain of the material [5,6,8,[12][13][14][15][16][17]. The change of the non-uniformity of properties can be fixed in various ways.…”