Forging methods of alloy steel tube
Forged steel pipe can be divided into free forging, upsetting, extrusion, forging, closed die forging, closed upsetting. Closed die forging and closed upsetting because there is no flash, material utilization is high. With a process or several processes may be complex forgings finishing. Since there is no flash, forging force area is reduced, the required load is reduced. Note, however, can not be restricted completely blank, this should strictly control the volume of the blank, to control the relative position of the forging die and forging measure, efforts to reduce die wear. Orbital can be divided into forging, swaging swing, roll forging, wedge rolling, ring rolling and cross rolling and other means. Orbital, put swaging and rolling ring also used precision forging.
In order to improve processing procedures before the material utilization, roll forging and rolling can be used as a cross-elongated material. Alloy steel tubes with the same rotary forging free forging is locally formed, it has the advantage compared to the size of forgings, forging a smaller force under the circumstances can be achieved is formed. Such methods include forging steel pipe,including free forging, machining material to extend from near the free surface of the mold surface, it is difficult to ensure accuracy, so that the direction of movement of the forging dies and swaging process controlled by computer, you can use lower forging force to obtain complex shape, high precision products. For example, the production of varieties, large-size turbine blade forgings. When the steel pipe temperature exceeds 300-400 ℃ (steel blue brittle zone), reaches 700-800 ℃, the deformation resistance will be drastically reduced, the deformation can also be significantly improved. Forged steel pipe according to different temperatures in the region, except for forging forging process and quality requirements, it can be divided into cold, warm forging, hot forging three molding temperature region. This division had a temperature range of no strict boundaries, generally speaking, there are forging recrystallization temperature region is called forging, forging without heating at room temperature is called cold forging.
At low temperatures the forging, forgings dimensional change is small. In the following 700 ℃ forging, less oxide formation, and no surface decarburization. Therefore, as long as the steel pipe deformation energy in the energy range of molding, cold forging easy to get good dimensional accuracy and surface finish. Just control the temperature and lubrication cooling, 700 ℃ the following warm forging can also get good accuracy. Hot forging, due to the deformation energy and deformation resistance are small, complex shapes can be forged large forgings. To obtain high dimensional accuracy of forgings, in the temperature 900-1000 ℃ hot forging process. Also, pay attention to improving the working environment for forging. Forging die life (2-5 one thousand forging, warm forging 1-2 ten thousand, ten thousand cold forging 2-5) forging temperature range as compared with the other is shorter, but it’s freedom, low cost .
Steel pipe blank when the cold deformation and work hardening, so die withstand high loads, therefore, requires the use of high-strength forging die and to prevent wear and bonded using hard lubricating film processing method. In addition, to prevent the billet crack, intermediate annealing to ensure that the needs of deformation when needed. In order to maintain good lubrication, the blank may be phosphate treatment. When working with continuous bar and wire rod, the current section can not be lubricated process, is studying the possibility of using phosphate lubrication method.
Post time: Oct-14-2019