STAMPING AND SHEET METAL FORMING——冲压成形和板材冲压【中英文.doc

STAMPING AND SHEET METAL FORMING冲压成形和板材冲压【中英文对照】STAMPING AND SHEET METAL FORMINGStamping is a kind of plastic forming process in which a part is produced by means of the plastic forming the material under the action of a die，stamping is usually carried out under cold state, so it is also called stamping, heat stamping is used only when the blank thickness is greater than 8-100mm.the blank material for stamping is usually in the form of sheet or strip, and therefore is it also called sheet metal forming. Some non-metal sheets (such as plywood. Mica sheet, asbestos. Leather) can be formed by stamping.Stamping is widely used in various fields of the metalworking industry. And it plays a crucial role in the industries for manufacturing automobiles. Instruments. Military parts and household electrical appliances. EtcThe process, equipment and die are the three foundational problems that needed to be studied in stamping.The characteristics of the sheet metal forming are as follows;high material utilizationcapacity to produce thin-walled parts of complex shapeGood interchangeability stamping pares due to precision in shape and dimension.Parts with lightweight. High-strength and fine rigidity can be obtained.High productivity. Easy to operate and to realize mechanization and autoimmunization.The manufacturer of the stamping die is costly. And there pore it only fits to mass production for the manufacture of products in small batch and rich variety. The simple stamping die and the new equipment such as a stamping nothing center are usually adopted to meet the market demands.The materials for sheet metal stamping include mild steel. Copper, Aluminum, Magnesium alloy and high-plasticity alloy-steel, etc.Stamping equipment includes plate shear punching press. The former shears plate into strips with a definite width, which would be pressed later, the later be used both in shearing and forming.2, characteristics of stamping formingThree are various processes of stamping forming with different working patterns and names. But these processes are similar to each other in plastic deformation. These are following conspicuous characteristics in stamping;The force per unit area perpendicular to the blank surface is not large but is enough to cause the material plastic deformation it is much less than the inner stresses on the plate plane directions. In most cases stamping forming can be treated approximately as that of the plane stress state to simplify vastly the theoretical analysis and calculation of process parameters.Due to the small relative thickness, the anti-instability capability of the blank is weak under compressive stress. As a result, the stamping process is difficult to proceed successfully without using the anti-instability device; therefore the varieties of the stamping processes dominated by tensile are more than dominated by compressive stress.During stamping forming the inner stress of the blank is equal toor sometimes less than the yield stress of the material in this point, the stamping is different from the bulk forming, during stamping forming, the influence of the hydrostatic pressure of the stress state in the bulk forming. In some circumstances, such influence may be neglected. Even in the case when this influence should be considered, the treating method is also different from that of bulk forming.In stamping forming. The restrain action of the die blank is not severs as in the case of the bulk forming, in bulk forming. The constraint forming is preceded by the die exactly the same shape of the part. Whereas in stamping. In most cases. The blank has a certain degree of freedom. Only one surface of the blank contacts with the die. In some extra cases, such as the forming of the blank on the deforming zone contact the die.The deformation in these regions is and controlled by the die applying an external force to its adjacent area.Due to the characteristics of stamping deformation and mechanics mentioned stamping technique is different form the bulk metal forming;The importance or the strength and the rigidity of die in stamping forming that in bulk forming because can be formed without applying large area on its surface. Instead. The simple die and the pneumatic forming are developed.Due to the plane stress or simple strain state in comparison with research on deformation or force and power parameters has been done, stamping forming can be performed by more reasonable scientific methods, based on the real time analysis on the sheet metal and stamping parameters by means of modern testing apparatus. Research on the intellectualized control of stamping proceedingIt is shown that there is a close between stamping materials. The research on the properties of the stamping forming, that is, shape stability on the properties of the forming that is, shape stability, has because a key point in stamping technology development, the technique of iron and steel industry, and provides a increasing sheet metal quality.3. CATEGORIES OF STAMPING FORMINGMany deformation processes can be done by stamping, the basic processes 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 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 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网can divided into several categories with the same forming properties and be studied systematically.The deformation zone in almost all of stamping forming is in the plane stress state. Usually there is no force or only small force applied on the blank surface. When is assumed that the stress perpendicular to the blank surface equals to zero, two principal stresses perpendicular to each other and act on the blank surface, the stress state and the deformation characteristics of the deformation of stamping forming can be denoted by the points in the coordinates of the plane principal stresses and the coordinates of the corresponding plane principal stains4. RAW MATERIALS FOR STAMPING FORMINGThere are a lot of raw materials used in stamping forming and the properties of these materials may have large difference. The stamping forming can be succeeded only by determining the stamping method, the forming the relationships between the material properties for stamping forming is as follows;Definition of stamping property of the material.Method to judge the stamping property of the material, find parameters to express the definitely material property of the stamping forming. Establish the relationship between the property parameters and the practical stamping forming. And investigate the methods of the property paramters.Establish the materials for stamping forming mainly include various metals and nonmetal plate. Sheet metal includes both ferrous and nonferrous metals. The most widely used materials are steel, stainless steel, aluminum alloy and various composite metal plates5. STAMPING FORMING PROPERTY OF SHEET METAL AND ITS ASSESSING METHODThere are direct and indirect testing methods to assess the stamping property of the sheet metal.Practicality stamping test the most direct method to assess stamping forming property of the sheet meals. This test is done exactly in the same condition as actual production by using the practical and dies. Surely, this test result is most reliable. But this kind of assessing method is not comprehensively applicable. And cannot be shared as a commonly used standard between factories.The simulation test is a kind of assessing method that after simplifying and summing up actual stamping forming methods, as well as eliminating trivial factors, the stamping properties of the sheet metal are assessed. Based on simplified axial-symmetric forming method under the same deformation and states between the seating plate and actual forming states. In order to guarantee the reliability and generality of simulation results, a lot of factors are regulated in detail. Such as the shape and dimension of tools for test, blank dimension and testing conditions.Indirect testing method is also called testing methods its characteristic is to connect analysis and research on fundamental property and principle of the metal in actual stamping forming. And then to establish forming property. Because the shape and dimension of the specimen/the deformation characteristics and stress form the indirect test are different from those of the actual one. So. The results obtained form the indirect not the stamping forming parameters. But are the fundamental parameters that be used to represent the stamping forming property of the sheet metal