What are the common faults of metal stamping parts?
According to the practical experience of quality management in our company’s stamping plant, the reasons and countermeasures for common problems in the production process of metal stamping parts are summarized, hoping to provide a useful reference for improving the quality of parts in the stamping plant.
1. Why do metal stamping parts appear twisted?
The stamping part is formed by punching the remaining material around the stamping part in the progressive die to form the shape of the stamping part. The main reason for flanging and twisting of stamping parts is the influence of blanking force. During punching, due to the existence of the punching gap, the material is stretched on the die side (the material is warped upward) and compressed on the die side. When using a stripper, press the material with the stripper to prevent the material on the die side from warping upwards. At this time, the stress state of the material also changes accordingly. As the stripper pressure increases, the material on the punch side is stretched (the pressure tends to decrease), while the material on the die surface is compressed (the tension tends to decrease). The reversal of the stamping is caused by the stretching of the material on the die surface. Therefore, when punching, pressing the material is the key to preventing the punch from flipping and twisting. Causes and countermeasures of flanging and twisting when stamping parts are bent.
It is caused by the burrs of the blanking parts during blanking. It is necessary to study the punching edge, and pay attention to check whether the punching gap is reasonable.
During the blanking process, flanging and deformation of the blanking parts occur, resulting in poor forming after bending, which needs to be solved from the blanking and blanking station.
Stamping parts are unstable during bending and are mainly used for U-shaped and V-shaped bending. In response to this problem, the key to solving the problem is to guide the position before bending, guide during the bending process, and press the material during the bending process to prevent the stamping parts from slipping during the bending process.
- Why do metal stamping parts tear?
The stamping process of the middle protective bracket in the common tear and skewed form of metal stamping parts is: blanking punching – punching incision – flanging forming – incision – flanging. Various forms of tearing and skewing of the intermediate protective bracket occur during the molding process. The easy-to-tear parts are mainly distributed in the hole shape of the workpiece, the junction of the R arc and the wall neck at the corner of the side wall, etc., which are produced by stamping. Due to the different process conditions, the proportion of each fracture site is also different. The tear can be a one-time formed tear or a tear due to the development of fatigue cracks.
Reason analysis, according to the actual situation on site, by checking the tearing position, fracture form and extrusion degree of the part, it is believed that the tearing and tilting behavior of the part is mainly reflected in the inversion molding process. The reasons for this process are as follows:
The forming process parameters are not implemented properly. During the forming process of the part, the process requires that the die, the pressing material core and the part must be closely combined, and the plastic deformation of the plate will actually deform when the machine tool slide slides down. However, due to the shortcomings of the unstable quality of the pressed parts, the pressure of the machine tool is in a state of unbalanced pressure beating during the production process. The main reason is that the processing technicians did not adjust the machine tool pressure in time according to the requirements of the process regulations at this stage, or passed the machine tool pressure stability information during the handover process of each shift, resulting in unstable parts quality.
The design defect of the flanging forming mold, the mold is shared by the left and right parts of one mold and two cavities, because the content of this process is not only flanging, but also the molding content. In addition, the parts are particularly complex, the curved surface is narrow, and the molding requires concave molding material The core is consistent with the molding surface, etc., resulting in a large molding stroke and a small pressing area of the mold structure. In the initial mold design, the designer only considered the small feature of the binder surface, and ignored the sliding stroke of the forming guide rail of the binder core.
3. Why is the surface quality of metal stamping parts poor?
There are many reasons for the surface quality problems of stamping products. The surface quality of coils, sheets and dies can affect the quality of the final stamped part. Operations during the stamping process and loading and unloading of station equipment can also damage parts. Therefore, the surface quality should fully consider the details in each link of the entire manufacturing process, and try to avoid quality problems that affect the appearance of the final product.
1. Coil material
The common bad phenomena of coil material mainly include the following aspects:
Foreign matter is mixed on the surface or inside of the steel plate
The foreign body is peeled off, and the coil material is in a scar-like state
Broken edge of roll
Corners (20-30mm) are deformed or wrinkled due to uneven stress
Scratches (caused by roller surface or foreign matter)
Roller slip caused
Irregularly damaged edges
After the foreign matter enters, the bulge is pressed out on the back of the coil (the foreign matter will disappear when it falls)
Roll marks (caused by foreign matter adhering to the roll)
Defective material outside the rules
Foreign objects cause visible grooves in the depth of the surface