自重是起重机技术性能指标之一。随着生产的发展,各类起重机都在向大起重量方向发展,起重机的自重也越来越大。例如国产的援外150吨门座起重机的自重达1600吨,日本三菱重工生产的600吨造船用龙门起重机总重达6500吨,由此可见起重机行业每年耗用的金属 Weight is one of the crane performance indicators. With the development of production, all kinds of cranes are developing in the direction of great lifting, and cranes have more and more weight. For example, China-made foreign aid 150 tons of portal cranes weighing 1,600 tons, Japan’s Mitsubishi Heavy Industries produced 600 tons of shipbuilding gantry cranes total weight of 6,500 tons, we can see that the annual consumption of the crane industry metal