Upgrading of the Processing Technology for Alloy Steel Crane Hooks: Achieving Performance Leaps through Multi-process Integration

Recently, a heavy equipment manufacturing enterprise has broken through the technical bottleneck in the processing of alloy steel crane hooks. Through a multi-process integration technology, the comprehensive performance of the products has been improved by 50%. This technology, which combines forging pre-treatment, numerical control milling and high-frequency quenching composite processing, has overcome the difficult problem of balancing the strength and toughness of the hooks. It has been applied to high-end scenarios such as the hoisting of nuclear power equipment. "The core of the processing of alloy steel crane hooks lies in the regulation of the microstructure." The technical director introduced that traditional cast hooks have problems such as coarse grains and stress concentration. The new solution adopts a dual path of "forging + numerical control precision processing": First, heat the steel ingot to 1200°C for die forging to obtain a uniform streamline fiber structure; then, carry out three-dimensional curved surface milling through a five-axis machining center, and control the thickness tolerance of the key load-bearing parts within ±0.1mm. In order to improve the surface hardness, the team innovatively adopted the "gradient quenching" process. The induction coil is guided by an industrial robot to carry out segmented heating on the neck and body of the hook, and cooperate with the water cooling system to achieve a gradient distribution of martensite structure. "This is equivalent to 'customizing' the mechanical properties of the hook." The test report shows that the yield strength of the new hook reaches 1200MPa, and the impact toughness is three times higher than that of the traditional process. A construction machinery enterprise has reported that the hook using the new process has continuously operated for 3000 hours on a 500-ton-meter level tower crane without crack propagation. The technical director of the customer said: "Especially the precision machining of the hook cavity has reduced the wear of the steel wire rope by 60%." The enterprise has established a digital processing model library, covering the full-process parameters of hooks ranging from 8 to 100 tons. The R&D team revealed that they are developing an online monitoring system based on the Internet of Things, which will enable the traceability of all elements in the processing process in the future. "This will promote the intelligent transformation of the processing of alloy steel crane hooks." With the industrial application of this technology, the localization rate of the core components of large-scale hoisting equipment in China is expected to exceed 85%, providing safer and more reliable equipment support for projects such as wind power installation and bridge construction.