1. Improve the stiffness and strength ofsand box
The bottom of lost foam casting sand box is reinforced with #10 channel steel. On the one hand, the stiffness is increased; On the other hand, the lost foam casting sand box is connected into an integral frame, which is conducive to the transmission of vibration force. The specific improvement scheme is shown in Figure 1. The improved lost foam casting sand box can eliminate the problems of desoldering of the support column and deformation of the bottom plate of the existing lost foam casting sand box.
The deformation of lost foam casting sand box is calculated by mechanical simulation software to ensure the improvement effect. Figure 2 shows the analysis of the deformation of the bottom and side of the lost foam casting sand box. The deformation of the bottom and side of the lost foam casting sand box is 1 / 3 of the original structural scheme, indicating that the improved scheme is feasible, which can improve the stiffness and reduce the deformation of the lost foam casting sand box.
2. Structure and control of vibrating system
The vibrating table is jointly developed by ZHY casting company and Yongji Shengyuan company. It adopts a waist holding clamping frame structure similar to Vulcan, with two vibrating motors on both sides. The lost foam casting sand box is compressed through 8 45 ° inclined planes, as shown in Figure 3. The control system is composed of four frequency converters and PLC to control the vibration acceleration, amplitude and angle. On the premise of ensuring that the Yellow mold is not deformed, the molding sand can flow orderly, fill all parts of the model evenly, and maintain a certain compactness.
3. Performance test of vibrating system
3.1 Vibration consistency test
Take 18 positions on the lost foam casting sand box, and take 3 ~ 4 points at different heights at each position, as shown in Figure 4.
Acceleration in up and down direction (z direction), 90 ° unidirectional compaction is set on the compaction table, the compaction force is 85%, and the molding sand height is 300 mm. The accelerations of upper reinforcement, middle reinforcement and lower reinforcement are shown in Figure 5.
As can be seen from Fig. 5, the values of accelerations at different heights at the same location point are basically close; Compared with the measured data of the original shaking table, the acceleration consistency at different positions is significantly improved; At positions 3 and 12, the acceleration is too small.
Acceleration in the fore-and-aft direction (Y direction), 0 degree one-way compaction is set on the compaction table, the compaction force is 85%, and the molding sand height is 300 mm. Select 8 points with high correlation with Y-direction acceleration, of which 6, 9, 15 and 18 correspond to the position of clamping point. The accelerations at each point are shown in Figure 6.
As can be seen from Fig. 6, the acceleration at different positions at the same height shows the law of low clamping point and high middle; At the same position, the accelerations of the upper reinforcement and the middle reinforcement are close, and the accelerations of the middle reinforcement and the lower reinforcement are close, and the acceleration of the upper part is obviously greater than that of the middle and lower part.
3.2 Effect of fit clearance between vibrating table and lost foam casting sand box on acceleration
During the acceleration measurement, it is found that the lost foam casting sand box and the vibrating table adopt 45 ° surface matching. When the matching condition is poor (the matching is linear contact or a small amount of surface contact), the acceleration near the matching surface is significantly lower than that at other positions. Therefore, grind the two matching surfaces. The final contact conditions of each point are as follows: 35% at position 6 and 65% at position 9, 70% at position 15 and 80% at position 18. Re measure the acceleration of 90 ° unidirectional vibration and 85% force, and the results are shown in Figure 7.
It can be seen from Fig. 7 that the acceleration at other locations except 5 ~ 8 points is significantly increased, indicating that the coordination between lost foam casting sand box and vibrating table has a great impact on the acceleration.
3.3 Mold filling effect test
The filling test chamber shown in Fig. 8 is used for testing. The statistics of filling effect show that it can meet the requirements of transverse filling of 100 mm.