Large Horizontal Vacuum Annealing Furnace Development

Large horizontal vacuum annealing furnace is a vacuum heat treatment equipment for annealing rare metal pipes such as titanium and zirconium. The longest size of annealing workpiece is 16m, which is the longest vacuum annealing furnace with the largest length and capacity in China.
Vacuum annealing furnace is an important technological process for the processing of intermediate and finished products of rare metals such as titanium and zirconium. Stress relief recrystallization annealing is carried out without oxidation and pollution to eliminate work hardening and restore plasticity. In recent years, with the rapid development of domestic aviation, aerospace, navigation, nuclear power, national defense and other cutting-edge industries, not only the demand for rare metal tubes and bars such as titanium and zirconium has been greatly increased, but also their quality and performance have higher requirements. The length of single tube and bar has also increased from 3 m~6 m to 10 m~16 M. Therefore, the current vacuum annealing process and equipment can not meet these cutting-edge requirements. The requirement of rapid development of end industry.
1. Main technical parameters
Type: Horizontal, external circulation type fast cooling, vacuum resistance furnace. 850 mm *16 000 mm (600 mm *600 mm *16 000 mm) in the effective average temperature range has the highest temperature: 900 C, the working temperature: 500 ~850 C, the temperature uniformity: +5 C, the temperature control precision: +1 C, the limit vacuum: 1.0 *10-3 Pa, the working vacuum: 1.0 *10-2 Pa, the pressure rise rate: <0.67 Pa/h, the rated heating power: 900 kW.
2. Design and Characteristics of Furnace Body Mechanism [2]
The furnace is a horizontal vacuum annealing furnace with cooling water jacket and is heated in a single room. It consists of furnace body, vacuum system, feeding and discharging system and rack, rapid cooling system of workpiece, heating system and electronic control system.
2.1. Furnace body
The composition and structure of the furnace body are shown in Figure 1. The furnace body is a horizontal cylindrical double-layer water-cooling structure, including shell, heating chamber, front furnace door and back furnace door. The material of shell flange is stainless steel, which is welded by argon arc welding. Open the front door and back, and load the front door. Furnace door is all stainless steel double-layer water-cooled elliptical head structure. Furnace door at feeding end can be opened and closed automatically. Pneumatic cylinder at the other end is locked and side door is opened. The furnace body is equipped with an inflatable interface and a valve, an exhaust valve, a standard temperature interface, a leak detection interface, etc. It is equipped with broadband superalloy heater. There are 5 layers of 0.5 mm thick stainless steel heat shield between broadband heater and water-cooled furnace wall. Rubber sealing ring is used between the furnace door and the flange of the furnace body to meet the requirements of high vacuum sealing. The sealing performance is stable and reliable.
2.2. Vacuum system
In order to quickly remove the impurity gases emitted from the chamber and materials during heat treatment and keep the chamber vacuum in line with the technological requirements, the equipment is equipped with two KT-800A diffusion pump units with strong pumping capacity. Both diffusion pumps are equipped with oil caps and temperature monitoring. They are equipped with heating power regulators to prevent oil return. At the same time, in order to prevent the contamination of the workpiece by the oil vapor of the vacuum pump, a low-temperature Freon cold trap was set up at the KT-800A diffusion pump port, which improved the cleanliness of the vacuum chamber.
2.3. Cooling Water System and Heating Chamber Quick Cooling System
Cooling water system includes water divider, water tank, valves, pipelines and various detection elements. It has the functions of water pressure, water flow, water temperature and water shortage alarm and interlocking. At the same time, in order to improve the efficiency of the equipment, the equipment is equipped with a gas fast cooling system. Quick cooling system consists of exchanger, magnetic fluid sealing device, fast cooling fan, soft nozzle, nozzle and other components. When the equipment runs to the fast cooling process, the argon filling valve opens and fills the furnace with high purity argon. When the gas pressure in the furnace reaches the set point, the fan in the fast cooling device starts, and the hot gas enters the heat exchanger for heat exchange. The cooled gas is fed into the furnace body through the ventilation duct, and the workpiece is cooled, so the cycle works. In this process, when the pressure in the furnace is lower than 70 kPa, the argon valve opens automatically to supply argon to the furnace.
2.4. Electronic Control System
The electronic control system consists of industrial computer, industrial control configuration software, data acquisition card, temperature controller (Europe) with communication, input and output module, PLC (with corresponding I/O expansion, communication interface), vacuum gauge with output control, with communication interface and so on. The electronic control system is composed of several control cabinets (factory design). The control cabinet panel has a vacuum system and a simulation diagram of the operation of the power supply and heating system. At the same time, the display of heating current, temperature and diffusion pump current in each section is also provided. The whole control system can be switched automatically and manually, and the operation cabinet is equipped with common control buttons. Calling and running the heating program can be operated from the host computer and the main thermometer respectively. An operation box is installed near the furnace door to facilitate observation and control of the feeding mechanism. The operation box includes buttons and indicator lights for feeding, discharging and stopping. The main circuit includes low-voltage fuse and fast fuse. Small transformer or power module is used to replace large-scale magnetic regulation after the vacuum unit is divided into sections, which reduces the occupied area, runs steadily, saves energy and protects the environment, and has low failure rate.
high temperature vacuum heat treatment microwave oven for hard alloy
vacuum atmosphere furnace for glass sintering
vacuum hydrogen furnace for brazing copper
plasma nitriding furnace for ammonia cooling