In this article we will discuss about the classification of metal forming processes. 1. Compressive Forming Processes: In these processes the plastic state is reached by application of uni-axial or multi-axial compressive forces. Examples are forging, extrusion, rolling, indenting, coining, etc. (Fig. 2.2) shows the stress states in the material during rolling, forging, coining and extrusion processes. In the rolling [...]
There are a number of processes, described below, which may be called unconventional forming processes or high energy rate forming processes. In these processes, unconventional sources of energy such as Explosive Forming, Electro-Hydraulic Forming, Magnetic Pulse Forming, Petro-Forge and Drop Hammer and Dynapak etc., are used. The release of energy is at extremely high rate and hence the name high [...]
For determining the normal and shear stresses on an inclined plane is by a graphical construction popularly known as Mohr's stress circle or simply Mohr's circle. For the sake of simplicity we take the co-ordinate axes along the principal stresses as shown in Fig. 3.5. The equations of the previous section when referred to this co-ordinate system become as given [...]
In this article we will discuss about how to analyze strain in metal forming process. Deformation: If on the application of forces, the particles of a deformable body change their relative positions with respect to one another, the body is said to be deformed. However, if there is no change in the relative positions of the particles with respect to [...]
In this article we will discuss about how to analyze stress in metal forming processes. Stress State at a Point: Let us first examine what comprises a complete state of stress at a point. State of stress at a point comprises the stress vectors or components of stress vectors acting on three mutually perpendicular planes passing through the point. With [...]
Slip lines may be constructed in the body which is undergoing plastic deformation or is at the yield point, provided the stresses, i.e. normal stress and shear stress, are completely known on its entire boundary. The construction gives an orthogonal network of slip lines covering the cross section of the deforming body. We can reach any point inside the body [...]
The following article will guide you about how to determine metal forming problems. Also learn about the three methods used for solving the metal forming problems. A simple tensile test is a case of uni-axial stress state, i.e. say σ11 ≠ 0 while all other components of stress state (or stress tensor) are equal to zero. For such a case [...]
In this article we will discuss about the geometrical properties of slip lines. 1. Hencky's First Theorem: Both the theorems of Hencky are geometrical properties of slip lines. The first theorem may be stated as follows. If a pair of lines of one type (say α) is intersected by lines of second type (β) then the angle between the tangents [...]
In cold rolling of steel strips and sheets, the yield strength of strip material is fairly high and very high specific roll pressures and hence rolling loads are experienced. Consequently high elastic deformations are also associated along with the plastic deformations. The elastic deformation of roll surface makes the roll surface flatter or in other words it increases the effective [...]
The torque is obtained by integrating the frictional force multiplied by roll radius over the arc of contact (lagging and leading zones). The negative sign before the second term is due to the fact that in leading zone the metal moves faster than the rolls hence it helps to rotate the rolls. The above integration leads to rather complex calculations. [...]