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What are the factors that affect the quality of automotive sheet metal parts?



Among the many factors affecting the quality of automotive sheet metal parts, the influence of the mold structure is very large. The forming effect of the deep drawing member is directly affected by factors such as the radius of the die, the geometry of the die working piece, the guiding mode of the die, the setting of the drawing rib (groove), and the size of the die hole.

Determine the radius of the punch and die fillet. The radius of the male and female molds plays an important role in obtaining the ideal deep drawing. The two main drawbacks of the cover draw members are wrinkling and tensile cracking. When the radius of the punch is too small: the bending deformation of the straight wall and the bottom of the blank increases, and the strength of the dangerous section is weakened;

When the radius of the die is too small, the tensile stress of the sidewall of the blank increases accordingly. In both cases, the drawing factor and the deformation resistance of the sheet are increased, resulting in an increase in the total pulling force and a decrease in the life of the mold.

If the radius of the punch or the mold is too large, the deformation resistance of the sheet is small, and the fluidity of the metal is good, but it reduces the effective area of the blanking and makes the part easy to wrinkle. Therefore, in determining the radius of the punch and the die, the deformation characteristics of the workpiece and the drawbead must be considered.


The geometry of the mold working part. Working parts of differently shaped molds also affect the quality of the drawn parts. The die is divided into two types: a flat die and a conical die. The use of a conical die generally provides a greater resistance to destabilization in the deformed zone of the blank, allowing relative thickness (t/D) relative to the flat end die. Smaller blanks do not wrinkle.

Mold guiding mode. The guiding of the drawing die includes two directions of a punch and a crimping head, a crimping head and a crimping head. The rationality of the mold guide rail directly affects the reliability of the drawing. The reasonable and stable guide rail can ensure the uniformity of the circumferential gap of the mold and the matching of the drawing surface, thereby ensuring the quality of the drawing member.

Ordinary drawing dies are mostly guided by guide plates or guide columns, and for deep drawing dies with large lateral forces during drawing (referring to workpieces with asymmetrical structures), the back block guides can be used for guiding. The ribs are generally disposed in the blank holder, and corresponding to the surface of the concave mold, that is, the concave ribs. The bumps may also be disposed on the surface of the mold, and the concave rods are disposed on the binder ring.


The role of the drawbead. 1. Strengthen the ability of materials to control material flow. 2. Increase the feed resistance, so that the blank is subjected to sufficient tensile stress, the rigidity of the drawing member is increased, and the surface defects caused by the rebound are reduced. 3. Expand the adjustment range of the blank holder force.

First of all, you need to know that the main function of the "dat spinnaker bar" is to increase the resistance of the material, so the "bumping force" also plays the same role. These two are complementary and can reduce the blanking force of the adjusting resistor. Sails the bar to achieve the same purpose.

Drawbead (slot) setting. The setting of the drawbead can increase the feed resistance of the corresponding part on the stamping surface and adjust the flow direction of the blank. However, if the position, number and shape of the drawbeads are not properly selected, a satisfactory cover cannot be pulled out. In general, the number and location of the drawbeads depends primarily on the shape of the cover, the undulation characteristics, and the draw depth.


For parts with deep drawing, 1-3 drawing ribs are placed in the straight part, and no drawing ribs are placed in the arc part. When the drawing depth of each part of the same part is large, the deep drawing part does not have a drawing rib, and the drawing rib must have a shallow rib. The direction of the drawbead must be perpendicular to the flow direction of the blank.

The drawbead is placed on the press of the blanking ring or on the press of the stamper, depending on whether the stamper is easily adjusted on the press. The drawbead is generally placed on the upper pressing surface, and the drawbeen groove is placed on the lower pressing surface to facilitate material positioning. In order to ensure the reliability of the mold, it is often necessary to verify and adjust the drawbeads designed on the mold during the mold debugging process.


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