At present, there are many precision forging processes used in production. According to the different forming temperatures, it can be divided into hot precision forging, cold precision forging, warm precision forging and composite precision forging. Today, we will introduce them in turn:
The first is the hot precision forging process: hot precision forging refers to the precision forging process forged above recrystallization temperature. Because of the high deformation temperature, the material has low deformation resistance and good plasticity when forging, and it is easy to form parts with complex geometry. Closed die forging is a common process method of hot precision forging. Due to die design, inaccurate blanking and insufficient manufacturing accuracy, closed die forging has great deformation resistance at the end of forging, which has adverse effects on die and equipment. This problem can be solved by using the principle of shunting decompression, that is, a shunting decompression cavity hole with a suitable shape and size is set at the last filling part of the closed cavity. When the cavity is completely filled, the excess metal of the blank flows out from the shunting cavity hole, which solves the problem that the blank volume and the cavity volume are not strictly equal, reduces the internal pressure of the cavity and prolongs the service life of the die.
The main purpose of heat treatment of wheel forgings is not only to eliminate stress and reduce hardness, but also to prevent white spots from appearing on forgings, and secondly to improve the uniformity of chemical composition and adjust and refine the microstructure of forgings. At present, the consistent view is that white spots are the result of the interaction between hydrogen and internal stress in steel. The most commonly used method to prevent the white spots on yongxinsheng forgings is to keep the temperature at 650 ~ 540℃ by using the rapid diffusion of hydrogen. The machining of crane wheels is a process of manufacturing products by mechanical means, that is, in a narrow sense, forging pieces are manufactured by special mechanical equipment such as lathes, milling machines, drilling machines, grinders, punches and die casting machines.
The processing of crane wheels is a process of changing the shape, size or performance of wheels by forging machinery (mainly lathes). According to the temperature state of machined forgings, it can be divided into cold working and hot working. Generally, machining at normal temperature does not cause chemical or phase change of wheels, which is called cold working. Generally, processing above or below normal temperature will cause chemical or phase transformation of forgings, which is called hot working. According to different processing methods, cold working can be divided into cutting processing and pressure processing.
Heat treatment, forging, casting and welding are common hot working in the processing of crane wheels in forging plants. In addition, cold and heat treatment are often used in assembly. When assembling crane wheels, the inner ring is often cooled in liquid nitrogen to reduce the size, and the outer ring is properly heated to expand the size, and then assembled together.
To sum up, it is the processing technology of crane wheels. Through such processing, high-quality crane trucks can be finally produced.