Problems in the production of metal shaped cans (1) Wholesale Commercial Furniture,Metal Restaurant Chairs For Sale,Chairs For Commercial Use,Commercial Furniture Sofa Foshan City Misirui Furniture Co., Limited , https://www.nbmisiruifurniture.com
At present, there are mainly problems: First, there are wrinkles at four rounded corners and leakage. The second is the leakage of the straight weld and the leakage of the weld triangle.
In response to these problems, we mainly conduct technical analysis from the following aspects.
First, the impact of raw materials on product quality
In general, most of the shaped metal cans used are tinned steel sheets. The tin-plated steel sheet is a low-carbon steel sheet having a certain metal ductility and a tin-plated surface. The tinplates currently used for cans are all electroplated tinplates. The production process of electroplated tinplates is: low carbon steel (steel water)→casting ingots and initial rolling (or continuous casting)→slab→hot rolling→strip → pickling → cold rolling → electrolytic cleaning → annealing → leveling → trimming → electrolytic cleaning → electroplating tin → reflow → passivation treatment → oiling → coiling → shearing → sorting → packaging (electroplating tin plate).
In order to meet the quality requirements of can making containers, and to adapt to the can making process, the process steps must be strictly controlled when producing tinplate. From the perspective of the production process of electroplated tin steel sheets, the factors affecting their mechanical properties are not only related to the heat treatment, but also related to the rolling direction. These are discussed in the study of the barrel flanging process.
Second, the impact of deformation characteristics on the quality of the product when the bottom is deepened
From the geometrical characteristics of the shaped can, there is a qualitative difference between its deformation and the deformation of the circular can parts. The biggest difference is that the deformation on the periphery of the deep drawing is not uniform. We can divide it into straight side parts of length A2r and B2r and four rounded parts of radius r (see Figure 1 for abbreviated). The rounded portion is a 1/4 cylindrical surface. Assuming that there is no connection between the straight side portion and the rounded portion of the shaped piece, the forming of the part can be assumed to be composed of the bending of the straight side portion and the deep drawing of the rounded portion. However, since the straight side portion and the rounded portion are connected together, there must be mutual interaction and influence during the drawing, so that the two parts are not simple bending deformation. In fact, from the perspective of the nature of the deformation, there is no clear boundary between the two parts.
When the profiled part is drawn deep, the deformation of the straight side portion and the rounded portion is as shown in Fig. 1. Before the drawing is deepened, the rounded portion on the surface of the blank is first divided into a grid composed of radial radiation and concentric arc, and the straight portion is divided into a grid composed of mutually equal equidistant equal lines. If the straight side portion of the profiled member only produces a bending deformation, the grid line on the side surface of the profiled member after the deep drawing deformation should be exactly the same as before the deformation. However, in fact, after the deep drawing deformation, the mesh size of the side wall of the profiled member undergoes a change in lateral compression and longitudinal elongation. The transverse dimension before deformation is ΔL1 = ΔL2 = ΔL3, and after deformation, the relationship is ΔL1 > ΔL1 > ΔL2 > ΔL3.
The longitudinal core inch before deformation is H1=△H2=ΔH3, and after deformation, it becomes the relationship of ΔH3>ΔH2>ΔH1>ΔH1. It can be seen from this dimensional change that the lateral compression and the longitudinal extension of the drawing deformation are uneven on the side wall of the straight portion of the profiled part. The deepening deformation is minimized in the middle portion of the straight portion, and the drawing deformation near the rounded portion is the largest. The distribution of the deformation in the height direction is also non-uniform, the smallest near the bottom position and the largest near the upper mouth. The deformation of the rounded portion is similar to the deep drawing deformation of the cylindrical part, but the degree of deformation is smaller than that of the cylindrical part having the same radius and height. Therefore, the radial radiation on the slab blank does not become an equidistant equal line perpendicular to the bottom plane after the deep drawing deformation, but is a diagonal line having a small distance from the upper portion to the lower portion.
The above various phenomena indicate that the degree of deepening deformation of the rounded portion and the degree of hardening caused by the deformation are reduced due to the existence of the lateral compression deformation of the straight portion, and the cylindrical portion having a height of 2 r and a height H is lower. . Therefore, the radial tensile stress necessary for the deep deformation of the rounded portion deformation region is also lower than that of the cylindrical member of the same size. The influence of the straight portion on the rounded portion is determined by the ratio r/B of the radius r of the shaped piece to the width B, or the relative fillet radius. The smaller the ratio r/B, the more significant the effect of the straight portion on the deformation of the rounded portion, that is, the greater the difference between the deformation of the rounded portion and the cylindrical member. When r/B = 0.5, the profiled member becomes a cylindrical member, and the above-described deformation difference does not exist.
On the other hand, since the longitudinal elongation deformation of the straight portion is smaller than the rounded portion, although the straight edge portion and the rounded portion move at the same speed at the bottom portion of the hair, the straight portion of the deformation region (the flange portion of the blank) The displacement speed is greater than the rounded portion, and the difference in displacement speed causes the belting action of the straight portion in the deformation zone to the rounded portion, and as a result, the bottom of the side wall of the rounded portion, that is, the tensile stress value in the dangerous section Reduced.
When the profiled part is drawn deep, correctly defining the shape and size of the blank not only saves the plate and the parts that are flush with the mouth, but also facilitates the deformation of the blank and ensures the quality of the part. When the size of the blank is too large, the tensile stress on the dangerous section will increase unnecessarily, which is unfavorable for improving the degree of deformation and reducing the process. When the local size of the blank is too large, this part will protrude from the deformation zone during the drawing process. Going out, not only the deformation of the protruding part itself is reduced, but also the deformation of the sheet in the adjacent part is difficult. The reduction in the degree of deformation of the blank size over a large part inevitably causes the deepening deformation to concentrate more on the rest, thus increasing the degree of uneven distribution along the periphery of the blank. The resulting wall thickness is uneven, and it is also easy to cause localized areas (such as four rounded corners) where the deformation is too concentrated, reducing the quality of the parts.
The principle of determining the blank when the profiled part is drawn is also to ensure that the area of ​​the damaged part is equal to the area of ​​the part, but the shape of the broken hair must ensure that the distribution of the material on the entire circumference coincides with the formation of the contour at each point on the periphery of the part. The need for side walls. Since the values ​​of tangential compression deformation and longitudinal elongation deformation of the metal at different points on the periphery of the part are different, it should be considered according to the uneven deformation characteristics of the shaped part, considering the shape and size of the material during the deformation process. The necessary corrections.
Since joining the international trade organization, the market has become more and more demanding on product quality, and packaging products are particularly prominent. Because good products have to enter the international market, the first problem to be solved is the backward historical pattern of “one type of products, two types of prices, and three types of packagingâ€. At present, the domestic paper, plastic, wood and glass packaging industries are booming. Only the metal container packaging industry is shrinking, especially the state-owned metal container packaging enterprises. Most metal container packaging companies are now moving their products to miniaturization. At present, the author has some opinions on the common problems of the special-shaped metal packaging barrels produced by domestic enterprises.
Third, the shape and size of the top blank of the barrel bottom determine the impact on product quality