小型轧钢机(工作原理+设计手册+外文文献翻译+CAD图纸)
Categories of stamping forming
Many deformation processes can be done by stamping, the basic processes of the stamping can be divided into two kinds: cutting and forming.
Cutting is a shearing process that one part of the blank is cut form the other .It mainly includes blanking, punching, trimming, parting and shaving, where punching and blanking are the most widely used. Forming is a process that one part of the blank has some displacement form the other. It mainly includes deep drawing, bending, local forming, bulging, flanging, necking, sizing and spinning.
In substance, stamping forming is such that the plastic deformation occurs in the deformation zone of the stamping blank caused by the external force. The stress state and deformation characteristic of the deformation zone are the basic factors to decide the properties of the stamping forming. Based on the stress state and deformation characteristics of the deformation zone, the forming methods can be divided into several categories with the same forming properties and to be studied systematically.
The deformation zone in almost all types of stamping forming is in the plane stress state. Usually there is no force or only small force applied on the blank surface. When it is assumed that the stress perpendicular to the blank surface equal to zero, two principal stresses perpendicular to each other and act on the blank surface produce the plastic deformation of the material. Due to the small thickness of the blank, it is assumed approximately that the two principal stresses distribute uniformly along the thickness direction. Based on this analysis, the stress state and the deformation characteristics of the deformation zone in all kind of stamping forming can be denoted by the point in the coordinates of the plane principal stress(diagram of the stamping stress) and the coordinates of the corresponding plane principal stains (diagram of the stamping strain). The different points in the figures of the stamping stress and strain possess different stress state and deformation characteristics.
(1)When the deformation zone of the stamping blank is subjected toplanetensile stresses, it can be divided into two cases, that is σγ>σθ>0,σt=0andσθ>σγ >0,σt=0.In both cases, the stress with the maximum absolute value is always a tensile stress. These two cases are analyzed respectively as follows.
2)In the case that σγ>σθ>0andσt=0, according to the integral theory, the relationships between stresses and strains are:
εγ/（σγ-σm）=εθ/（σθ-σm）=εt/（σt -σm）=k 1.1
where, εγ，εθ，εt are the principal strains of the radial, tangential and thickness directions of the axial symmetrical stamping forming; σγ，σθand σtare the principal stresses of the radial, tangential and thickness directions of the axial symmetrical stamping forming;σm is the average stress,σm=（σγ+σθ+σt）/3; k is a constant.
In plane stress state, Equation 1.1
3εγ/（2σγ-σθ）=3εθ/（2σθ-σt）=3εt/[-（σt+σθ）]=k 1.2
Since σγ>σθ>0,so 2σγ-σθ>0 and εθ>0.It indicates that in plane stress state with 961
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