Lost foam casting requires that the molding sand can fill the mold space tightly during molding. Therefore, the vibrating system is one of the key equipment. The factors affecting the compaction effect include molding sand, sand adding device, sand box, compaction table and control system. Baozhu sand is better than quartz sand because it is nearly spherical; The stiffness and consistency ofsand box are good to ensure that the exciting force of vibrating table can be well transmitted to molding sand; The vibrating table and its control system are the source of exciting force and the basis for determining the filling capacity of molding sand.
Figure 1 shows the basic structure of GK vibrating table in the United States. The lost foam casting sand box is not clamped. The vibrating table has three convex round tables, and the bottom of the lost foam casting sand box corresponds to three pits. The vibration acceleration can reach 1.6 ~ 2.2 g, and the irregular transverse excitation force is generated by the side impact of the circular platform.
Figure 2 shows the basic structure of Vulcan vibrating table in the United States. The lost foam casting sand box is surrounded by the frame of the vibrating table. After the vibrating table is lifted, the lost foam casting sand box is lifted on the 45 ° surface at the bottom 4, and the top is pressed on the 45 ° surface at the upper 4 by hydraulic drive. The excitation force comes from four vibration motors installed on both sides. The motor is connected with the position feedback encoder. The encoder can detect the motor speed and the included angle between the eccentric block and the reference, so as to ensure that the motor 1, 2 and 3 have an accurate phase angle relative to the motor. Through the control of this phase angle, the vibration at any angle in the plane can be realized theoretically.
There are many types of vibrating tables produced by domestic equipment manufacturers, which can be mainly divided into lost foam casting sand box clamping type and lost foam casting sand box non clamping type. Each type has double motors, 4 motors and 6 motors. However, from the feedback effect of manufacturers, the transverse filling capacity is not ideal, and yellow mold pre plugging resin sand is often required.