Large horizontal vacuum annealing furnace
The large horizontal vacuum annealing furnace is a vacuum heat treatment equipment for annealing rare metal pipes such as titanium and zirconium. The longest dimension of the annealed workpiece is 16m, which is the vacuum annealing furnace with the largest length and capacity in China.
The vacuum annealing furnace is an important process for the intermediate and finished processing of rare metals such as titanium and zirconium. It is subjected to stress-free recrystallization annealing in the absence of oxidation and non-polluting to eliminate work hardening and recovery plasticity. In recent years, with the rapid development of cutting-edge industries such as aviation, aerospace, navigation, nuclear power, and national defense, the demand for rare metal pipe rods such as titanium and zirconium has been greatly improved, and the quality and performance have been improved. It is required that the single length of the tube bar is also increased from 3 m to 6 m to 10 m to 16 m. Therefore, the current vacuum annealing process and equipment are difficult to meet the requirements of rapid development of these cutting-edge industries.
1, the main technical parameters
Type: horizontal, external circulation type quick cooling, vacuum resistance furnace. Effective temperature range Φ850 mm×16000 mm (600 mm×600 mm×16000mm) Maximum temperature: 900°C, working temperature: 500°C~850°C, temperature uniformity: ±5°C, temperature control accuracy: ±1°C, limit Vacuum degree: 1.0×10 - 3 Pa, working vacuum: 1.0×10 - 2 Pa, pressure rise rate: ≤0.67 Pa/h, rated heating power: 900 kW
2, the design and characteristics of the furnace mechanism
The furnace is a cooling water jacket type horizontal vacuum annealing furnace, which is heated indoors. It consists of furnace body, vacuum system, feeding and discharging system and material rack, workpiece rapid cooling system, heating system and electronic control system.
The furnace body is a horizontal cylindrical double-layer water-cooling structure, including a casing, a heating chamber, a front furnace door, and a rear furnace door. The shell flange material is made of stainless steel and is welded by argon arc welding. Open the door before and after, the front door is loaded. The furnace door is an all-stainless steel double-layer water-cooled elliptical head structure. The furnace door at the feeding end can be automatically opened and closed, and the pneumatic cylinder at the end of the furnace door is locked, and the door is opened in the side. The furnace body is equipped with an inflation port and a valve, a vent valve, a temperature temperature interface, a leak detection interface, and the like. Configure a broadband superalloy heater. A 5-layer 0.5 mm thick stainless steel heat shield is placed between the broadband heater and the water-cooled furnace wall. A rubber sealing ring is used between the furnace door and the flange of the furnace body to achieve high vacuum sealing requirements, and the sealing performance is stable and reliable.
In order to quickly eliminate the large amount of impurity gases released during the heat treatment of the gas in the furnace chamber and the material, the vacuum degree of the furnace chamber is kept in accordance with the process requirements. The equipment is equipped with two sets of KT-800A diffusion pump units with powerful pumping capacity. Both diffusion pumps are equipped with oil retaining caps and temperature monitoring, and are equipped with a heating power regulator to prevent oil return. At the same time, in order to prevent the contamination of the workpiece by the vacuum pump oil vapor, a low-temperature freon cold trap is arranged at the KT-800A diffusion pump port to improve the cleanliness of the vacuum chamber.
Cooling water system and heating chamber rapid cooling system
The cooling water system includes a water separator, a water tank, a valve, a pipeline and various detecting components, and has functions such as water pressure, water flow, water temperature, water shortage alarm and interlocking. At the same time, in order to improve the working efficiency of the equipment, the equipment is equipped with a gas rapid cooling system. The rapid cooling system consists of an exchanger, a magnetic fluid seal, a quick cooling fan, a soft connector, and a take-over. When the equipment is operated to the rapid cooling process, the argon-filled gas valve is opened, and the furnace is filled with high-purity argon gas. After the gas pressure in the furnace reaches the set point, the fan in the rapid cooling device starts, the hot gas enters the heat exchanger for heat exchange, and the cooled gas is sent to the furnace body through the ventilation duct to cool the workpiece, so that the cycle works. During this work, when the pressure in the furnace is lower than 70 kPa, the argon valve is automatically opened to supply argon gas to the furnace.
Electronic control system
The electronic control system consists of industrial computer, industrial control configuration software, data acquisition card, temperature control instrument (European) with communication, input and output module, PLC (with corresponding I/O expansion, communication interface), vacuum gauge with output control, with Communication interface and other components. The electronic control system consists of several control cabinets (designed by the factory). The control cabinet panel has a vacuum system and a power supply heating system operation simulation diagram. There are also various sections of heating current, temperature and diffusion pump current display. The entire control system can be switched automatically and manually, and the control (control) cabinet is equipped with common control buttons. The calling and running heating programs can be operated from the upper computer and the main temperature controller respectively. An operation box is installed near the furnace door to facilitate observation and control of the feeding and discharging mechanism. The operation box includes buttons, such as feeding, discharging, stopping, and the like. The main circuit includes low-voltage fuses and fast-acting fuses. After the vacuum unit is segmented, small transformers or power modules are used instead of large-scale magnetic modulation to reduce floor space, stable operation, energy saving and environmental protection, and low failure rate.