Clutch shell forming analysis
Tensile strength ≥270MPa, forming inner corner size is R7mm. The formed parts belong to high-strength stamping, and the forming area is large, large presses must be used, and the stamping process requirements are high. The clutch is a part of the vehicle drive system with high assembly size and structural size requirements. It is a high-precision stamping, with the shape of the part in axial degree < 1 mm, the position tolerance of the assembly hole relative to the size of the center hole ≤0.5 mm, and the circumferential Angle tolerance ±20 '.
2. Clutch shell stamping process analysis and design
Through the analysis of the parts and the formulation of the forming process, mainly by pressing, drawing and flanging three processes. The process analysis pattern is decomposed and calculated. Firstly, the process calculation is simplified in the form of overall deep drawing. Disassemble the parts into 2 different units A and B for calculation respectively.
Process analysis of stamping forming
(1) Analyze and calculate the blank size. All dimensions of the drawing parts are calculated according to the medium line of the thickness of the material, as shown in Figure 5. d1 diameter is ϕ 401mm, d2 diameter is ϕ473mm, using the maximum size; The drawing size h1 of the first step is 33.5mm, and the flanging size h2 of the second step is 43.5mm.
Part A structural dimensions
Part A size calculation: The theoretical reference value DA≈599.8mm can be obtained by using the formula DA2=d2 +4 (d1×h1+d2×h2). After actual trial production, it is determined that the diameter DA is 566mm, which is less than the theoretical calculation value. The flanging part of h2= 43.5mm can be calculated according to the approximate drawing value. In the calculation process, the blank diameter is DA=590mm. Size calculation of part B: According to the part size structure R=r, as shown in Figure 6, the blank diameter of part B: Using the formula DB2=d2 +4× d1 ×H-3.44r×d1, where H= 23.5mm, the theoretical reference value DB≈ 503.6mm can be obtained. After actual trial production, it is determined that the blank diameter DB is 566mm, and the blank diameter DB= 500mm in the calculation process.
Part B structural dimensions
According to the structural dimensions of part A and part B, the blank size is preliminatively determined through integrated calculation, and the actual size is verified by calculation after trial production. Considering the material fiber direction of the sheet when cutting and arranging, the economical cutting plate layout and sheet layout size of 535 mm× 535 mm were designed.
Sheet layout size
(2) Analysis of deep drawing process scheme. The parts are cylindrical parts with flanges, which are formed by pressing, drawing and flanging. In order to simplify the calculation, the pressing part is regarded as drawing. Here, only the drawing coefficient and drawing times of h1 and H parts are calculated to determine the number of molds. The calculation process is as follows:
(1) h1 and H are different height sizes of drawing on the same starting plane, and can be formed by one drawing according to the production experience of similar stamping parts;
② Deep inside rounded corner R7mm (material thickness 7mm);
③ The relative thickness of the material: 100t/D=100×7/500=1.4; Drawing series m=(d + 2t)/d=(394 + 2 × 7)/480=408/480=0.85, where the thickness t=7 mm; DB=500 mm;
④ Through the calculation of the thickness of the material and the drawing coefficient, it is determined that the drawing can be formed once, and the crimping phenomenon will not occur when the holder is used;
⑤ The drawing force of the holder ring is calculated according to the formula F drawing =πdtRmK1, where d is the diameter of the drawing part (center line), and 394+7=401 mm; t is the material thickness, 7mm; Rm is the tensile strength of the material, which is 270 MPa; K1 is the coefficient, take 1.1; It can be calculated as follows: F =3.14×401×7×270×1.1= 2 617 752.06N;
⑥ Flanging force is calculated by the formula F flanging =0.7KBt2Rm/R+t, calculated according to U-shaped bending force, where K is the safety factor, take 1.3; B is the flanging width, which is calculated to be about 1 350 mm; Rm is the tensile strength of the material, 270 MPa; t is the material thickness, 7mm; R is the inside rounded corner, take 7 mm. The calculation results are as follows: F=0.7×1.3×1350 × 49 × 270/14=1160 932.5N; ⑦ Set F total =1.2 (F pull +F turn) =1.2×3 778 684.56 N=4 534 421.472 N, that is, F total > 5 000 kN;
