Preset of compression technique of auto parts guard cover and its mould
It can be seen that the dimensional accuracy of the part processed by deep drawing can meet the dimensional accuracy requirements of the part. This part is an appearance part, which has high requirements on appearance, so it should be considered when arranging the process sequence and mold design.
Process plan determination According to process analysis, the possible process plans are mainly as follows: Option 1: Blanking deep drawing (outer edge 5424, height 22) → reverse drawing (inner circle shape 5257) → shaping (inner and outer edge) → Punching (10 to 558 flanging bottom hole) → flanging (10 holes) punching the inner hole 5251.
Plan two: deep drawing 5257 → shaping → trimming and punching → flanging (outer edge) → punching (10?558 flanging bottom hole) → flanging (10?558). Scheme 3: Drawing 5257 → shaping → trimming and punching (5251, 10?558 flanging bottom hole) → flanging (outer edge and hole edge).
The advantages of the first plan: blanking and pulling the outer edge is conducive to forming the outer edge, and the blanking and deep drawing are compounded together, which can reduce the number of molds. Reverse drawing is conducive to the forming of the part and to ensure the quality of the appearance of the part. , Punching and flanging to separate the mold is simple, high strength.
The shortcomings of the first plan: due to the large drawing depth (36mm) of the reverse drawing process, the metal flow is difficult, and the material can only be formed by thinning, so the part is easy to be cracked. The blank size is not easy to adjust due to the blanking and deep drawing composite, and the mold is more complicated.
The advantages of the second plan: the drawing blank adopts square material, and the size of the base blank can be adjusted according to needs. The drawing die (inner straight cylinder) is simple and easy to manufacture. The central hole of the 5251 trimming and punching hole is positioned, which is easy to ensure the concentricity (hole and shape). , 10?558 flanging bottom holes and 5251 holes are punched separately to ensure the strength of the mold. , The first step of deep drawing can use a large radius circular arc concave die, thereby improving the appearance quality of the drawn part, and also facilitating the flow of metal materials, which is conducive to the progress of the drawing.
The shortcomings of the second plan: 6 sets of molds are required, and there are many procedures, but the molds are relatively simple and easy to manufacture. It is more suitable for our factory’s small batch production of bus chassis. Solution three advantages: 4 sets of molds are required, which is relatively small. It has the 1, o, and advantages of the second scheme. Disadvantages of scheme three: 10 to 558 flanging bottom holes and 5251 holes are punched out at one time, the wall thickness of the mold cavity is small, and the mold strength is poor. Turn the edge of the small hole and the outer edge at the same time, the hole is easy to deform. Moreover, the wall thickness of the mold cavity is small and the strength is poor.
Through the above comprehensive analysis, it can be seen that the second option is more reasonable, the mold structure is simple, and the part size is easy to guarantee. Therefore, the second option is selected as the process plan for this piece. Technological calculation: the unfolded diameter D0 of the part shape curve segmented blank is calculated according to the calculation method of the blank size of the deep drawing part of the rotating body with complex shape, such as. Divide the generatrix (ie contour curve) of the drawing parts into simple straight lines and arc segments 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. Calculate the length of each straight line and the length of each arc and The distance from each segment to the axis of the workpiece.
Determine one-time drawing height and one-time deep-drawing die fillet radius. Because the diameter of the workpiece is d=259>200, the die fillet radius is determined by the following formula. The fillet radius of the drawing punch r convex = (0.6～1) Xr concave=(0.6～1) X12=7～12 the fillet radius of the part r concave=3<rconcave 1minr convex=3<rconvex 1, so it is needed In the shaping process, the rounded corner radius shown in the drawing can be achieved by shaping the part once.
Process trimming and punching die The structure of the die is as shown in (1). The edge trimming and punching are performed by positioning the outer circle of the stretched part to ensure the concentricity of the trimming outer circle 5452 and the central hole 5251 with the straight cylinder circle 5257. (2) Three scrap knives (piece 26) are used to cut the surrounding scraps, making it easy and safe to take out the scraps. (3) The upper die adopts rigid return material (pieces 8, 11, 12) in order to use the punching mechanism of the press. </rConcave1minrConvex=3
Conclusion The design of the process and the mold is in line with the actual situation. After the actual pressure test, it can meet the quality requirements of the imported products and achieve the expected purpose.
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