The wheel blanks are removed from the mold and are usually demolded by hand flaps (Fig. 1). When flipping, there is no relative movement between the aluminum pad 1, the grinding wheel blank 2 and the lower die plate 3 in order to ensure that the blank is not damaged. When the worker flips the mold, the three pieces must be lifted up to a total weight of 35kg, and the total weight of each shift is more than 7000kg, which is both physically expensive and easy to make.