The stamping process of metal stamping parts and measures to prevent waste
In the stamping process, whether the stamped parts can be smoothly formed and meet quality requirements is influenced by many factors such as stamping equipment, mold process lubrication, and sheet metal properties. Among them, the stamping formability of the sheet metal is a more important factor.
Due to concerns about metal stamping parts; The quality requirements for stamping sheets are no longer just about no cracking, but also require high shape accuracy and dimensional accuracy. Therefore, measuring the formability of stamping sheets from three aspects: anti cracking performance, anti wrinkling performance, and anti rebound performance is relatively reasonable. This measurement method is also beneficial for selecting stamping sheets and solving stamping quality problems in practical production.
The reasons for the fault of metal stamping parts are as follows:
Firstly, the classification of grades cannot accurately represent the stamping performance of sheet metal; Secondly, the evaluation of the forming difficulty of complex shaped stamped parts is not reasonable enough; The correlation between the performance indicators of the sheet metal and the quality of the stamped parts is still unclear. With the development of society and the advancement of stamping technology, people have put forward requirements for the quality of stamped parts, especially automotive cover parts. They not only require stamped parts to have no cracks, but also require smooth and beautiful surface quality (shape accuracy) and interchangeability (size accuracy). This also puts forward requirements for stamped sheets. Therefore, under this new requirement, the original evaluation of the performance of stamped sheets is no longer suitable, and corresponding new standards are used to measure their formability.
If the stamped part does not bounce back, its size will be the same as that of the mold, and the dimensional accuracy of the stamped part will be determined by the manufacturing accuracy of the mold. However, in reality, when the punch has not yet separated from the die after stamping, the shape and size of the stamped part are the same as those of the punch. After the stamped part is separated from the mold, this shape and size cannot be "frozen" and will undergo a degree of elastic recovery. This kind of recovery not only changes the shape of the car stamping part, but also changes the dimensional accuracy. The smaller this change, the better the "freezing" property of the stamped part. The "freezing" property of the shape accuracy and dimensional accuracy of the stamped part is not only related to the plastic deformation of the sheet metal during the stamping process, but also closely related to the elastic recovery size of the sheet metal after plastic deformation. In general, product designers mainly consider the strength and stiffness of the parts when designing them, in order to determine the materials that should be used. At this time, it is impossible to consider the production process of the materials in detail. However, in stamping production, the stamping performance of the sheet directly affects the success or failure of the stamping process. Stamping process designers examine the impact of sheet performance on stamping process and stamping part quality from a process perspective, verify whether the selected materials are reasonable, and if the stamping performance of the selected materials cannot meet the requirements of stamping process and stamping part quality, they need to reselect the materials.
The production method of stamping parts has its own unique characteristics. It uses molds, so the precision of the produced workpieces is extremely amazing, reaching the micrometer level. When used to produce various small and ultra small workpieces, it has its own advantages and can reduce some errors and errors.
When producing a large number of identical workpieces through stamping, a high degree of repeatability accuracy can be achieved, making all workpiece specifications astonishingly consistent and providing users with a certain user experience during use. The surface has its own position in the market.
Especially, we can see that stamping parts themselves are also a production method that can achieve many production effects. This pressure extrusion production method can easily punch out the ribs, flanges, or holes required for the performance of the workpiece, which can produce complex shaped workpieces and reduce production costs.
Analysis of the causes of scrap metal stamping parts from five perspectives: human, machine, material, method, and environment.
A. Poor quality of stamping raw materials, such as uneven thickness and hardness, and incorrect cutting or slitting dimensions;
B. Improper installation, adjustment, and use of stamping molds, such as the limit column not being attached and the mold not being closed during stamping production.
C. The stamping operator did not feed the stamping strip correctly along the positioning or did not feed the strip according to the gap;
D. Due to long-term use, stamping dies may experience changes in clearance or wear on their working and guiding parts;
E. Due to prolonged impact and vibration, the fastening parts of the stamping die become loose, causing relative changes in the installation positions of the die;
F. The stamping operator's negligence resulted in not following the operating procedures.
G. The quality management system is not sound, or the quality inspectors do not conduct inspections on time, and timely spot checks are conducted to detect any defects or abnormalities.
F. The accuracy of the punch press is insufficient due to long-term disrepair, resulting in a decrease in parallelism between the upper and lower tables or a decrease in punching force.
II The main measures that stamping processing plants need to take to prevent metal stamping waste
A. The stamping raw materials comply with the specified technical conditions (strictly inspect the specifications and grades of the raw materials, and if conditions permit, conduct laboratory tests on workpieces with high dimensional accuracy and surface quality requirements.)
B. Strict adherence to the various stages specified in the stamping process specifications;
C. The tools and equipment used, such as presses and stamping dies, should work in normal working conditions;
D. Establish a strict inspection system during the production process, inspect the first piece of stamped parts, and only put them into production after passing the inspection. At the same time, strengthen inspections and promptly handle any accidents that occur;
E. Adhere to the civilized production system, such as using appropriate workstation equipment for the transportation of stamped workpieces and blanks, otherwise it will crush and scratch the surface of the workpiece, affecting the surface quality of the stamped parts;
F. During the stamping process, it is necessary to clean the mold cavity and organize the workplace in an orderly manner. The processed workpieces should be placed neatly.
When selecting stamped sheet metal from the perspective of stamping technology, the following main tasks need to be done: ① Detailed deformation characteristics of stamped parts can be analyzed. For complex shaped parts, the "calculus method of stamping deformation analysis" can be used for analysis. Firstly, the complex shaped parts are "decomposed" into several simple shaped "parts", and their respective deformation characteristics and possible quality problems are analyzed. Then, the mutual influence between each simple shape is comprehensively considered to determine the overall deformation properties of the stamped part in the stamping process, and the "dangerous" parts and their deformation properties during stamping forming are determined, and the main quality problems that will occur in the stamping process are predicted. ② Determine the requirements for the stamping performance of the sheet metal based on the deformation properties of the hazardous areas and potential quality issues identified through deformation analysis of the stamped parts Based on the performance requirements of the board determined by the previous analysis, select the appropriate board and verify whether the newly selected board meets the strength and stiffness requirements of the parts.
