The structure of aluminium vacuum brazing furnace should be advanced and reasonable. The heating elements should be uniformly arranged along the 360 degree circumference of the heating chamber, and the temperature uniformity is high. High power and high pumping speed vacuum unit should be adopted. The vacuum recovery time is short. Zonal temperature control, small workpiece deformation, high production efficiency. It has the advantages of low cost, stable and reliable mechanical action, simple operation and flexible input of programming technology. Manual/semi-automatic/automatic control, automatic alarm/display of faults. It can meet the requirements of vacuum brazing and quenching of the typical parts provided by users. The aluminium vacuum brazing furnace should have reliable automatic control, monitoring, tracking and self-diagnosis functions at the international advanced level. Furnace supporting products and functional components have advanced international level, and can meet long-term, stable and reliable production needs. The energy-saving effect of the equipment is good.
Introduction of Main Structure and Performance of Equipment
Horizontal cylindrical furnace body, open doors at both ends, square full metal screen heating chamber, external circulation cooling system, diffusion pump vacuum unit.
1. Furnace door opening: pneumatic opening and locking structure.
2. Furnace body: horizontal cylindrical furnace body, water-cooled sleeve double-layer structure, in which the inner wall material is stainless steel. Open the door at both ends, one end is the charging door, the other end is the maintenance door.
3. Heating chamber (furnace gallbladder): square all-metal screen heating chamber, six-sided heating, good temperature uniformity.
3.1. The thermal insulation structure of four-layer all-metal screen is adopted. The material of insulation screen is 304.
3.2. The heater uses nickel-chromium strip.
3.3. The heating chamber frame material is stainless steel.
3.4. The support material frame is heat-resistant steel.
3.5 In order to ensure the accuracy of brazing temperature, the heating chamber is designed to be controlled independently by multiple heating zones.
3.6. The insulator is high purity alumina ceramics.
4, cooling system:
The cooling system fan and heat exchanger are placed outside the welding vacuum chamber to reduce moisture absorption in the furnace, which is conducive to improving the pumping speed.
4.1. The motor is a special motor for vacuum furnaces (which is allowed to operate at temperatures not exceeding 180 C and pressures higher than 0.05 Mpa).
4.2， heat exchanger adopts copper high finned tube heat exchanger (copper tube, aluminum fin)
5. vacuum system:
5.1. Diffusion pump, Roots pump and mechanical pump three-stage pump system. The inlet of diffusion pump is equipped with anti-return oil cold trap and maintenance pump.
5.2. Valve with spare gauge seat; mechanical pump and Roots pump front end with a leak detection point
5,3. Effective cold traps and filters are installed in the vacuum system.
5.4 In order to increase pumping speed, two sets of such units are allocated.
6, electronic control system:
6.1 Temperature control of vacuum furnace is composed of touch screen, Japanese programmable temperature controller, thyristor regulator and “k” thermocouple. Many imported thermometers are coordinated by setting value communication. In addition, several thermocouples can be connected to temperature inspection instrument to monitor the temperature values of different parts of the workpiece.
6.2 Vacuum control. The high and low vacuum in the furnace are measured by compound vacuum gauge. The vacuum gauge displays the measured value and outputs the signal to the PLC to control the vacuum system.
Range range: from atmospheric pressure to extreme vacuum
6.3 Quick cooling control: automatically (or manually) filling protective gas into the furnace, starting the fan to achieve rapid cooling between the furnace body and the heat exchanger. Quick cooling cycle can adjust the cooling rate by controlling the charging pressure.
6.4 Automatic and manual control of working process: Using programmable logic controller (PLC, model FX2N) of Mitsubishi Company of Japan, the whole working process of the equipment is interlocked control, which has safety interlocking protection and automatic treatment measures for vacuum, temperature, pressure of refilling body, pressure of cooling water and misoperation in the furnace. It is equipped with sound and light alarms, and the equipment can operate automatically and manually, and can be switched at any time. Such as: (1) unqualified vacuum, can not be heated; (2) low water pressure, can cut off the welding room heating power supply and diffusion pump power supply; (3) over-temperature, automatic shutdown of heating power supply, etc.
6.5 The on-site process record of vacuum furnace uses multi-channel liquid crystal paperless recorder, which is equipped with large capacity memory and long-term data storage. Trend curve, bar chart and real-time value of large screen display are adopted. The configuration of digital interface can facilitate data storage and transfer.
6.6 Low Voltage Electrical Apparatus are all domestic famous brand and joint venture products, which have been tested with high reliability. The panel is equipped with large display screen reflecting the working status of the equipment.
7, water cooling system
Water cooling system has water pressure monitoring alarm, flow regulating valve and water flow indicator, rigid steel pipe for main pipeline and tap water branch for use in case of circulating water failure or special circumstances.
8. Workpiece conveying system:
It is composed of track and feeding truck. The feeding truck lifts the workpiece through hydraulic mechanism.
9. The other parts of the equipment are: inflatable system, workpiece temperature measuring device, pneumatic device, etc.