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Stability of Metal Stamping Parts Production and Its Influencing Factors

2019/9/21 8:41:37 click:

What is stability? Stability is divided into process stability and production stability. Process stability refers to the process plan that meets the requirements of producing qualified products with stability; Production stability refers to the stable production capacity in the production process.
First, let's take a look at the main factors that affect the stability of metal stamping parts, namely: the use of mold materials; The strength requirements of the mould structure; Stability of stamping material performance; Fluctuation characteristics of material thickness; The range of material changes; The resistance of that stretch rib; Change range of blank holder force;  Selection of lubricants.
As we all know, the metal materials used in stamping dies involve many kinds. Due to the different roles played by various parts in the dies, the requirements and selection principles for the materials are also different. Therefore, how to reasonably select mold materials has become one of the most important tasks in mold design.
When selecting mold materials, in addition to requiring the materials to have high strength, high wear resistance and appropriate toughness, the characteristics and yield requirements of processed product materials must also be fully considered, so as to meet the stability requirements of mold forming.
However, in actual operation, because mold designers tend to choose mold materials based on personal experience, unstable mold forming problems often occur in metal stamping due to improper selection of mold parts.
In the mold design stage, it is necessary to carry out the necessary strength check calculation for the mold structure, and the following precautions should be taken when selecting materials:
(1) punch stress < punch material allowable compressive stress
(2) in order to improve the bending strength of punch, should choose the material with large elastic coefficient
(3) According to Euler formula, check the stability.
It is worth noting that in the process of metal stamping, because each stamping plate has its own chemical composition, mechanical properties and characteristic values closely related to stamping performance, the instability of stamping material performance, the fluctuation of stamping material thickness and the change of stamping material not only directly affect the precision and quality of metal stamping, but also may lead to mold damage.
Take tensile bar as an example, it occupies a very important position in metal stamping.  In the process of stretch forming, the forming of the product needs to have a certain size and a proper distribution of pulling force along the fixed periphery. This pulling force comes from the acting force of the stamping equipment, the deformation resistance of the edge material and the flow resistance on the blank holder ring surface. However, the friction between the mold and the material is not enough if the flow resistance is generated only by the action of the blank holder force.
For this reason, it is also necessary to set tensile ribs that can generate greater resistance on the blank holder ring to increase the resistance of feeding, thus causing greater plastic deformation of the material to meet the requirements of plastic deformation and plastic flow of the material.  At the same time, by changing the size and distribution of the tensile bar resistance and controlling the flow speed and feed rate of the material into the mold, the effective adjustment of the tensile force and its distribution in each deformation region of the tensile member is realized, thus preventing the quality problems such as cracking, wrinkling, deformation and the like of the product during stretching and forming. From the above, it can be seen that in the process of drawing up the stamping process and die design, the tensile resistance must be considered, the tensile ribs should be arranged according to the variation range of the blank holder force and the form of the tensile ribs should be determined, so that each deformation area can be formed according to the required deformation mode and degree.
In order to solve the problem of die stability of metal stamping parts, the following aspects should be strictly controlled:
(1) in the process formulation stage, through the analysis of the product, predict the defects that may occur in the production of the product, so as to formulate a stable manufacturing process plan;
(2) the implementation of standardization of production process, production process standardization;
(3) establishing a database and continuously summarizing and optimizing the database; With the aid of CAE analysis software system, the optimal solution is obtained.
YIXIN PRECISION METAL AND PLASTIC LTD, with 15 years of focus on metal stamping parts, 20,000+sets of mold customization and production experience, and 100+ sets of mold processing capacity per month. Punching accuracy can reach 0.01 mm, and 16 quality inspections are strictly controlled. It can solve your urgent time problem, stamping precision problem and production quality problem for metal stamping parts.
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