What are the technological measures to improve the quality of spindle forgings?
The quality of spindle forgings is closely related to the quality of steel ingots. As the weight and size of the ingot increases, the inherent defects of the ingot become more serious, making forging and welding of internal defects more difficult.
In order to improve the quality of spindle forgings, the quality of steel ingots should be maximized during smelting and casting. Of course, in the forging process, improving the forging process is also an important aspect. For example, by changing the ingot type, billet shape, tool structure, operation method, etc., the uneven temperature field of the billet is used to create a favorable stress and deformation state, so that the spindle forging can be completely forged and internal defects. Welded together to achieve the purpose of improving the internal structure and improving the mechanical properties.
1. Change the ingot shape of the steel ingot: In order to improve the quality of the large steel ingot, the ingot shape should be a steel ingot with a large riser, a large taper, a small height-diameter ratio, and a polygonal ingot. As the ingot diameter ratio becomes smaller, the elongation forging ratio increases. For general shaft forgings, if the forging ratio meets the forging requirements, the intermediate upsetting can be eliminated and deep drawing can be used directly.
For the forging of hollow forgings, hollow steel ingots can be used. This can reduce the number of fires and injuries, shorten the forging operation time, save metal materials, and also improve the quality of the spindle forgings, such as the transverse mechanical properties will be significantly improved.
2. Change the shape of the blank: During upsetting, in order to uniformly deform the length of the ingot, the riser end can be pressed into a concave shape after the ingot is chamfered, so that the upsetting can not only reduce the shape of the side drum, but also increase the amount of deformation accordingly. degree. It is a short and thick ingot. After the ingot is chamfered, the middle of the ingot can be pressed into a concave shape, and then the ancestors can be disturbed to obtain the above effect.
3. Changing the tool structure can improve the intrinsic quality of the spindle forgings, such as the convex arc anvil. After the anvil is lengthened, a larger reduction can be obtained, thereby improving the welding effect of the internal defects of the steel ingot.
4. Surface cooling forging: This forging method is also called center pressing method and hard shell forging method. After the billet or ingot heated to the initial forging temperature is released, it is forced to cool by air blowing or spraying. The surface temperature of the billet is cooled to 700~800°C; immediately forging, the core temperature is still very high, the temperature difference between the inside and outside can reach 250~350°C, the surface is like a hard shell, low temperature, high resistance, not easy to deform; the heart is surrounded by a hard shell High temperature, low resistance, easy to deform. Therefore, when the billet is forged along its axis, the core is subjected to a strong three-way compressive stress, resulting in deformation similar to closed-die forging, which is conducive to the generation of hole defects in the forging center. If you turn it 90° and press it again, the center compaction works better.
5. Forging and welding composite process: the quality of spindle forgings is closely related to the quality of steel ingots. Generally, the quality of large ingots is difficult to guarantee, while the quality of small ingots is generally better. In recent years, with the development of large-section welding technology, the use of forging welding technology to manufacture spindle forgings has emerged, that is, first forging several small steel ingots into billets, and then tailor-welding them into spindle forgings.