Molding process and mold design of the hottest air

2022-10-01
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Air cooled diesel engine oil tank forming process and mold design

Abstract: through the analysis of oil tank process and mold design practice, this paper summarizes the process analysis method of special-shaped parts forming and the principles that should be considered in mold design. Key words: special shaped parts, process analysis, structural design, mold design drawing. The first is the sketch of air-cooled diesel engine oil tank. This paper will start from the production process, determine the best parting surface, and qualitatively analyze its stress and strain, so as to take corresponding control measures in mold design. The development of plastic industry and new material industry will be implemented from five aspects, In order to discuss the process analysis method of drawing special-shaped parts and the principles that should be considered in die design. 1、 Process analysis 1. Determine the parting surface. The oil tank shown in Figure 1 belongs to a rectangular box type part, and its placement state during use is consistent with that shown in Figure 1. There is an oil tank port riveted on the upper plane as shown in Figure 1 D, and an oil outlet nut on the lower plane as shown in Figure 1 e. the oil tank port and the oil outlet nut must be assembled before the oil tank is welded. The principles for selecting the parting surface of box shaped parts are: meeting the requirements of workpiece use, centralized process, less tooling investment and less labor consumption. Through the analysis of the structure of the box shaped part, the oil tank body should be made of two parts, which are welded by the seam welding machine in the workshop. If the upper and lower bodies have different structures, the upper and lower bodies need two sets of forming dies, reshaping dies and trimming dies. To meet the above principles, these two parts should be exactly the same in order to reduce mold investment. In view of this, there are three parting schemes for this box type part. The following is a comparative analysis of the three schemes from three aspects: the use of the oil tank, molding process, economy and technology, so as to determine the best parting scheme. Scheme ① is in cross section a. The assembly and riveting of the oil tank port and the oil outlet nut are convenient. However, due to the existence of the oil tank mouth, the periphery of the parting surface cannot be fully seam welded, which increases the welding process cost. In addition, because the upper and lower parts of the oil tank are high rectangular boxes, they all need to be drawn twice and shaped once. The mold investment is high, there are many processes, and the process is difficult. In addition, high rectangular box drawing requires high drawing performance of plates, which will increase the cost of raw materials. Scheme ② is in longitudinal section B. The upper and lower bodies are drawn with ordinary rectangular boxes, which is easy to form, centralized process, less tooling investment and less labor consumption. However, the fuel tank mouth must be offset, and the surrounding of the parting surface cannot be fully seam welded, which increases the welding process cost, and the offset of the fuel tank mouth is detrimental to the actual use. Scheme ③ type C of intermittent section. The upper and lower bodies are shaped parts for deep drawing, and the assembly and riveting of the oil tank port and the oil outlet nut are more convenient. All the edges of the parting surface can be sewn and welded, which fully conforms to the principle of selecting the parting surface of box shaped parts, meets the requirements of workpiece use, has centralized process, less tooling investment and less labor consumption. The comprehensive cost is the lowest. However, compared with ordinary box shaped parts, the drawing performance of shaped parts is similar to that of many engineering plastics, and it is difficult to draw. To sum up, scheme ① has guaranteed product quality, but there are many processes, large labor consumption and large investment in tooling and equipment. Scheme ② there is too much manual labor and the product quality is poor, which affects the appearance quality of the whole machine. Scheme ③ the process is centralized, the tooling investment is less, the labor consumption is less, and the comprehensive cost is the lowest. However, the mold structure is relatively complex, and measures to eliminate defects must be taken to ensure the product quality. We determine scheme ③ as the best scheme. Therefore, we suggest that the product structure be inclined section disposal type. 2. The upper and lower body structures after part drawing process analysis and classification are shown in Figure 2. They are asymmetric plane flange parts. In the sheet metal drawing process, the stress in the thickness direction is relatively small and can be ignored, so it is generally regarded as the plane stress state. Take a unit body at point a of flange corner. According to the basic principle of deep drawing, its stress state is plane stress state, as shown in Figure 3, and the radial is tensile stress σ 1. Tangential is compressive stress σ 3. Radial tensile stress σ 1. The distribution along the periphery of the box type part is uneven, and the middle of the fillet is the largest and the middle of the straight edge is the smallest. Tangential compressive stress σ 3 is distributed like radial tensile stress σ 1. It is the largest in the middle of the fillet, and gradually decreases as it is farther away from the fillet. Taking a unit body at B can be approximately simplified to an axisymmetric stress state, as shown in Figure 4, σ R is tensile stress, σθ Is compressive stress, σ R and σθ The maximum value is reached in the middle of the fillet. In the process of deep drawing, the resistance of the fillet part is greater than that of the straight edge part, so the material flow speed of the fillet part is slower than that of the straight edge part. Due to the large compressive stress at the fillet, the excess material of the fillet cannot flow smoothly to the straight edge part, so bulge defects will occur at the corner, the fillet of the flange part (A1 some industry experts' introduction points) will wrinkle, and concave, distortion, relaxation, ripple and other defects will occur at the straight edge part. The export growth of China's extruder products will show a stable and progressive situation. The solution is to properly set the drawbead at the appropriate position. The function of the drawbead is: 1. To increase the feeding resistance and avoid the defects such as concave surface, distortion, relaxation and corrugation of the drawn part; 2. To adjust the flow condition of the material to make the flow resistance of all parts uniform in the drawing process, or to make the amount of material flowing into the mold cavity suitable for the needs of all parts of the workpiece, so as to prevent the phenomenon of "more wrinkles, less cracks". The layout principle of drawbead is: the sequence number requires the layout principle 1 to increase the feeding resistance, improve the degree of material deformation, and place a whole circle or intermittent drawbead or drawbead 2

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