In 2021, Chinastar M&C received a request from a large enterprise to accurately measure the weight and 3D center of gravity position of large special-shaped casting parts. The workpiece weighs about 90 tons, has irregular shape, uneven length, ranging from 6 meters to 11 meters, uneven width, ranging from 3 meters to 6 meters, and uneven height, ranging from 0.4 meters to 1 meter. The internal structure of the workpiece is also not unified. Some positions are solid and some positions are hollow. It is required that the error between the design weight and test weight of the workpiece shall not be greater than 20kg, and the error between the design position and measurement position of the 3D center of gravity shall not be greater than 2mm, otherwise it is a waste product. The direct cost of measuring the weight and center of gravity of the large workpiece is more than 70 million.

       After receiving this project, Chinastar M&C organized relevant technicians to repeatedly study and discuss the structure, test method and construction scheme of the workpiece. The correctness of the implementation scheme in theory, the feasibility of the method and the operability of on-site construction are analyzed. After many simulation exercises, it is finally determined that the measurement scheme we formulated can meet the requirements of customers.

       To this end, we designed a 100 ton special electronic scale and calibrated the scale at a fixed point to make the displayed division value reach 2kg (the conventional maximum can only be 20kg), the invisible division value reach 0.2kg (the conventional maximum can only be 2kg), and the measurement error after fixed-point calibration is less than 0.01% FS.

       After the actual test results come out, the error between the design weight and the actual weight of 90t special-shaped workpiece is 6kg, less than the required 20kg, and the error between the 3D design center of gravity position and the test center of gravity position is 1.53mm, less than the required 2mm. Fully meet the requirements of customers!

       There is a successful case of measuring the weight and center of gravity of 90 ton special-shaped workpiece. We have also successively undertaken the measurement of the weight error of the symmetrical axis of 30 ton large irregular rotating body. The required error is 6kg, and the final measured error is 1.640kg. The required error of 3D axis center position measurement of 50t large special-shaped parts is 1.8mm, and the final measured error is 1.25mm.

       The successful measurement of the weight, 3D center of gravity position and symmetry axis weight error of large-scale special-shaped workpieces once again proves that the design technology, smelting technology, mold technology, casting technology, machining technology, weight measurement technology, 3D center of gravity measurement technology and symmetry axis weight error measurement technology of large-scale workpieces in our country have reached a very high level.

       This set of test system for the weight, 3D center of gravity position and symmetry axis weight error of large-scale special-shaped parts developed by our company can be widely used to measure the weight, 3D center of gravity position and symmetry axis weight error of various large, medium and small-scale special-shaped parts.