Vacuum hydrogen sintering furnace at 2100℃

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This paper introduces the technical performance and structure of the vacuum hydrogen sintering furnace at 2100℃, expounds the working process and mechanism characteristics of the equipment, points out the problems encountered in the installation and debugging process, and points out the solutions.

Vacuum hydrogen sintering furnace is a kind of equipment for sintering new materials in two states of vacuum and hydrogen. One equipment can work in different environments. This equipment is widely used in the sintering of special ceramics and electronic materials.

High temperature vacuum hydrogen sintering furnace features:
(1) The heater is made of tungsten wire mesh system and welding process. The three leading electrodes on the tungsten wire mesh heater are fixed on the electrode of the upper furnace cover. The surface of the tungsten wire mesh heater has low composite and long service life.
(2) Adopt high precision control instrument, high temperature control precision, temperature difference in the average temperature area ±6℃.
(3) The reflector outside the heater adopts an integral suspended all-metal panel structure, so that the high-temperature deformation of the reflector panel has been controlled.
(4) The temperature control of the equipment adopts the Japanese conductive FP23 high-precision temperature controller, so that the equipment can operate according to the process setting curve to meet the requirements of different processes.
(5) The transmission system is controlled by the turbo worm reducer, which drives the turbine to drive the lower furnace cover lifting drive on the ball screw. The ball screw and the guide rod are installed vertically and parallel, ensuring the positioning and stability of the furnace cover. This transmission mechanism is compact, ball screw is not affected by torque, bending moment, type screw is in the best stress state.
(6) The equipment can be divided into two working environments, vacuum and hydrogen, which can be controlled separately. The working environment and process curve can be selected according to the characteristics of the sintered material. The hydrogen control system of the equipment stops when the vacuum environment is used, and the vacuum system stops when the hydrogen environment is used.

At present, the equipment has passed the long-term production test, and its performance index has reached the design requirements. It is widely used in the electronic industry and other special materials industry.

1. Performance parameters and composition of the equipment

1.1 Equipment performance parameters Gas consumption H2≤4(pressure 1.5-2.5kPa) cubic per hour; N2≤6(pressure: 1.5-2.5kPa) cm3 / h

1.2 Components of the equipment The high-temperature vacuum hydrogen sintering furnace at 2100℃ is composed of 11 components.

2. Working process and structure of each part of the equipment

(1) furnace. Furnace for vertical cylindrical furnace bottom for elliptical head, the furnace cover for QiuGuanXing head, on the furnace cover and sealing furnace with sealing ring, adopt double above water cooling structure, the inner stainless steel, the outer layer of high quality carbon steel, sandwich with stainless steel water ring, so that the uniform cooling without dead zone, on the furnace body is equipped with water-cooled electrodes, thermocouple, vacuum pipeline, the upper furnace tube has lead electrodes, with 3 w support bar on the bottom, to support the tray.

(2) Heat insulation screen in furnace. In order to ensure the high cleanliness and production process required by vacuum, the reflector adopts all-metal structure. The inner 5 layers are tungsten screen, followed by 7 layers of molybdenum screen, and all side insulation screens are suspended on the high-temperature stainless steel tube by tungsten rod. All insulation screens are made with the latest technology, and the expansion between the sheets is non-interference, which can effectively eliminate the thermal deformation.

(3) Heater. The heater USES tungsten wire mesh heating body, three phase star connection method, heating power is 120KW. The heating power supply adopts reliable and advanced voltage regulator, which is maintenance-free during normal use. The use of tungsten wire mesh heater can effectively reduce the surface load of the heater and improve the service life of the heater.

(4) Temperature measuring device. W – Rhenium thermocouple coated with W – protective tube is used for temperature control and temperature measurement, with reliable operation, stable performance and long service life.

(5) Vacuum system. A 2X-30 rotary vane pump and k-300T oil diffusion pump were used to pump out the furnace. Lanzhou vacuum company is used for oil diffusion, Nanguang vacuum company products are used for rotary vane pump, and Shanghai Second valve Factory is used for vacuum valve, all of which are well-known brands in China.

(6) Water cooling system: Pipe filter and electric contact pressure gauge are installed on the main inlet pipe, and flow switch is installed on the cooling water return pipe for reducing water supply, water shortage, alarm and interlock protection. The water-cooled parts of each heating electrode adopt quick discharge structure, which is convenient for cleaning and maintenance.

(7) Lifting mechanism and platform: The platform is composed of standard steel frame and legs, covered with steel plates, with a beautiful appearance.

3. Electric control system

The vacuum hydrogen sintering furnace system is controlled by Japanese Omron PLC programmable controller and Kunlun State upper touch screen to realize man-machine dialogue. Omron PLC and the upper touch screen through Ethernet connection, to achieve data exchange. Omron PLC controller main control vacuum hydrogen sintering furnace furnace vacuum system and the working state of hydrogen under the logic control of the valve, the alarm signal acquisition, the stove has over current, short circuit, water shortage and overtemperature, interlocking, interlocking perfect automatic protection measures, such as failure to immediately send out sound and light alarm, delay for a few minutes after cutting off the heating power, in order to set aside the necessary time for the operator’s judgment and handling, important fault alarm immediately after implementation. The upper touch screen realizes the man-machine dialogue screen: the vacuum system control screen, the air path system control screen, the temperature curve monitoring screen. In order to avoid the failure of the furnace caused by a sudden power cut, the system is installed with on-line UPS uninterruptible power supply. In case of a sudden power cut, the original control system can be maintained for 0.5 hours, and the program can be executed from the original working state after 5 minutes of call. Key components are imported products, users can rest assured to use. The control cabinet is equipped with ventilation and heat dissipation as well as automatic lighting. Japanese conductive temperature controller is used for temperature control, which can set and control the temperature curve. The function of copy printing can be realized by recording temperature curve with paperless recorder. Temperature control adopts 1 WRE5/26 armored thermocouple to collect temperature, and Japanese conductive FP23 high-precision temperature control instrument to control temperature process curve. Japanese conductive FP23 high-precision temperature control instrument and upper touch screen realize on-line observation and recording of temperature curve through RS485 communication protocol. The vacuum system and the upper touch screen also realize the online detection and recording of vacuum degree through RS485 communication protocol.

The overall layout of the equipment is compact and reasonable, and the operation and maintenance are convenient. The electric control cabinet, gas distribution cabinet and water supply cabinet are all sprayed with plastic spray. The whole equipment is brightly painted, the parts are electroplated and blackened, which makes it beautiful and generous in appearance.

Through the assembly and debugging of a number of similar devices, the performance indexes of all aspects of the devices have met or been recognized by users due to the design requirements.

After continuous improvement, the high temperature vacuum hydrogen sintering furnace at 2100℃ has stable equipment performance and good operation, and the technical parameters meet the customer’s requirements. On this basis, another 2400℃ high temperature vacuum furnace was developed.