The contact area between the punch and the stretched blank is large when the punch starts to stretch. The contact between the punch and the drawn blank should start near the middle when the punch starts to stretch. Near the middle of the contact, the punch can pull the material evenly into the die during the drawing process. If the contact is not close to the middle, the drawing blank may move through the top of the punch during the drawing process. When the punch starts to stretch, the contact with the stretched blank must be more and more dispersed. Determine the shape of the binder surface The binder surface is the part of the die radius that is outside the die. The pressing ring presses the drawing blank on the die pressing surface, and the punch stretches the drawing blank not only to make the material on the pressing surface not wrinkle, but it is more important to ensure that the material drawn into the die can not be made. Wrinkles do not break. Since the part does not have a flange surface, the binder surface can only be supplemented by the process supplement. The requirement for the shape of the pressing surface is that the pressing ring presses the drawing blank on the surface of the pressing surface of the concave die to form the pressing surface, and wrinkles and creases should not be formed to ensure the drawing of the drawing blank by the punch. Otherwise, the stretched parts will form ripples and wrinkles during the stretching process, resulting in cracks. Therefore, the shape of the pressure surface is composed of plane and cylindrical surfaces. The problem that must be considered when determining the shape of the binder surface. Reduce the stretching depth. The pressing surface has a certain curved shape, that is, the main method of lowering the drawing depth is that the drawing blank is pressed into a certain curved shape under the pressing ring and the pressing surface of the concave mold. The punch must have a stretching effect on the stretched blank. This is an important factor that must be fully taken into account in determining the shape of the binder surface. The shape of the binder surface, which is sometimes determined to reduce the stretching depth, does not stretch the drawn blank, although it satisfies the curved shape of the drawn blank. This kind of pressing surface cannot be used. The unfolding length of the pressing surface is shorter than the unfolding length of the surface of the punch, and the punch may stretch the stretched blank. This shows that the unrolled length of the pressing surface is shorter than the unrolled length of the punch surface. Determining Process Additions In order to achieve stretching and create good stretch conditions, the process replenishment must be carefully considered to meet the requirements for drawing, pressing, and trimming processes. The flanges on the parts are unfolded and the gaps are filled, and the additional parts of the process form a tensile part. The process replenishment part is an indispensable part of the stretched part. After the stretching, the supplementary part of the process is to be repaired. The process replenishment part is also a necessary material consumption. Therefore, it is necessary to be able to stretch out the satisfactory stretched part. It is possible to reduce the number of process replenishments, and how much of the process replenishment is a sign of whether the cover design or stamping process is advanced or not. The types of process replenishment are: the trim line is on the press surface of the drawing piece and is trimmed perpendicularly. The press surface is the flange face of the cover itself. On the underside of the drawing, trim the edge vertically. The trim line is trimmed on the slope of the tensile member and trimmed vertically. The trim line is trimmed horizontally on the side wall of the draw piece. The trim line is trimmed on the side wall of the draw piece. According to the characteristics of the piece, using a variety of process supplements, as shown. Three kinds of process replenishment a second trimming method b trimming method c fifth trimming method 2.4 determination of tensile ribs determine the direction of stamping, process replenishment and the shape of the binder surface is to determine whether the tensile elongation can be satisfied The pre-requisite for the drawing piece, but the stretching rib can control the flow of the entire drawing blank on the pressing surface, and increase or decrease the feeding resistance at various places on the pressing surface as needed. Therefore, the position, number, and shape of the tensile ribs are handled improperly, and it is impossible to draw satisfactory tensile members. The effect of tensile ribs is as follows: increase the feed resistance and increase the plastic deformation of the material. Adjust the feed resistance and the amount of feed in all parts of the pressing surface. The feeding resistance of the straight part and the rounded curve part on the outer contour of the drawing piece is uniform and the material flow is uniform. Increase the radial tensile stress, reduce the tangential compressive stress, and prevent the material surface from wrinkling. Reduce pressure requirements and improve tensile stability. Prompting stretch ribs in areas that are easily wrinkled can increase the pressure regulation range without being affected by air cushion pressure fluctuations. Improve the stiffness of the stretched part. Due to the uneven stretching depth of the piece and uneven billet deformation, the semicircular tensile bars are adopted, and the depth of the tensile bars is not equal, the depth of the tensile bars is deep at the straight line, and the depth of the tensile bars is shallow at the corners. . Z Purlin Machine,Roll Forming Machine,Galvanized Steel Z Purlin Frame Yuanding Science And Technology Co., Ltd. , http://www.wyrollformingmachine.com