车身外表面变形校正方法英文文献和中文翻译(2)
The measurement techniques is then introduced and the oil stoning and laser scanning are used to measure and record the surface low/distortions which are then digitized for further mathematical analysis. A geometry morphing method is proposed to prevent the surface deflection. Finally, three approaches that aim to correct surface low/distortions are tried out and die morphing proves to be a practical and effective method. 2 Replication of the Surface Low/distortion Experimental dies which represented the surface low/distortion were designed. The surface low/distortion can be seen around the corner of the stoned specimens. The preliminary tryouts on these experimental dies were carried by using cold rolled grade 5 (CR5) steel, a typical material for exterior panels. Various measurements were performed. The experiment results have shown that the designed experimental dies successfully replicated the surface low/distortion phenomena, which are very common in a vehicle’s outer panels. 2.1 Die designs techniques The experimental dies are designed to have basic depression features so that the typical surface low/distortion behavior which next to the depression features can be replicated. Various depression features are collected and reviewed in automotive outer panels before designing the dies. For a general and fundamental study, some basic geometry shapes are used to capture the features of the vehicle’s outer panels. Fig. 2 shows the four basic depression shapes being considered. Five variables are introduced to describe the geometry of a typical depression feature: depression depth (H in Fig. 3), upper sectional radius (RU in Fig. 3), lower sectional radius (RL in Fig. 3), plan view radius (RP in Fig. 2) and plan view angle (P in Fig. 2). Fig. 2. Plan view of the four basic depression shapes Fig. 3. Illustration of geometric variables and die setup Fig. 4 shows the three-dimensional explosive view of the solid die. Punch and die inserts are made for these depression features to reduce material and construction costs through utilizing common die components, which are shown in Fig. 3. Fig. 4. Three-dimensional explosive view of the solid die design Fig. 5(a) and Fig. 5(b) are pictures of the upper die assembly and lower die assembly, respectively. The punch and die inserts are shown in Fig. 6. These inserts are used to study the effect of the design variables on the surface low/distortion behavior by simply switching the inserts. Fig. 5. Construction of the die Fig. 6. Interchangeable die inserts The values of the five design variables vary from part to part. In practice, only the plan view radius RP, plan view angle P and depth H vary in a wide range. The upper sectional radius RU and lower sectional radius RL do not vary as much. In this experiment, considering variation of RP, P and H while keeping RU and RL constant for simplicity. As is shown in Fig. 2, P has values of 60°, 90°, 120°, and 240°, respectively. For each P, the radius RP can be the values of 10 mm, 20 mm, 30 mm, and 40 mm. 2.2 Measurement techniques and experiment results Oil-stoning is used to check the existence of surface low/distortion. The low/distortion profiles are then sketched from the stoned specimens onto paper and scanned into computer for digitization. A white-light scanner is used to get the surface low/distortion contours. Also, a coordinate measurement machine is employed to look at potential low/distortion zone. This measurement system is to monitor the deformation in the panel so that the occurrence time, location and magnitude of surface low/distortion can be identified and be used to correlate with numerical simulations, which in return help guided the experiments and provided information on the hard-tomeas-urequantities. CR5 steel is used to test the validity of the experimental die. The stamped specimens with four different depression shapes are shown in Fig. 7. The experiment shows that only specimens with plan view radius (R) of 20 mm and 30 mm, plan view angle () of 60°, 90°, and 120°, and reverse draw depth (H) of 5 mm and 10 mm literally have surface low/distortion and are oil stoned, white light scanned and CMM measured. Fig. 7. Representative stamped specimens Figs. 8(a)–8(c) show the surface low/distortion profiles of stoned specimens with the same plan view radius (R) of 20 mm and reverse draw depth (H) of 5 mm, and the different plan view angle () of 60°, 90°, and 120°, respectively. (a) Stoned specimen with P = 60°, RP = 20 mm, H = 5 mm (b) Stoned specimen with P = 90°, RP = 20 mm, H = 5 mm (c) Stoned specimen with P = 120°, RP = 20 mm, H = 5 mm Fig. 8. Surface low/distortion profiles The location and magnitude of the maximum surface low/distortion are read from CMM measurements and the latter of all scenarios are recorded on Table 1. From Table 1, some conclusions have been drawn: all of the depression depth, plan view radius and plan view angle have influence on surface low/distortion, and depression depth affects the most. Hence, when production concession is pursued to reduce surface low/distortion, reduce the depression depth first; the relationship between depression depth and surface low/distortion is positive, while the relationship between plan view radius/angle and surface low/distortion is negative. Table 1. Summary of maximum low/distortion magnitudes
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