After more than half a century of development, the first generation mesh belt furnace has gradually developed from heating under oxidative atmosphere to the second generation of protective atmosphere, less and no oxidation heating, and then to the third generation of controlled atmosphere heating, the fourth generation of computer management, In the 21st century today, how will the mesh belt furnace develop and what are the characteristics
The driving force for the development of the heat treatment mesh belt furnace today comes from the market demand like other products, and the development results come from the advancement of technology. my country's reform and opening-up policy is greatly promoting and accelerating the development of the heat treatment industry.
The mesh belt furnace technology in the 21st century will have distinct characteristics of the times, with four major characteristics: intelligent heat treatment, high-quality heat treatment, low-cost heat treatment, and clean heat treatment.
1.1 Intelligent heat treatment
The research and development personnel use the latest CAD program and heat treatment database, computer simulation technology and control technology, and adopt a highly flexible and intelligent integrated control and management system for the mesh belt furnace and its production line.
In the future, the operator of the mesh belt furnace only needs to input the number of workpieces and drawings to be processed into the computer, and the whole set of equipment will process high-quality products by itself.
At present, the real-time multi-project operation control of the entire system has been realized. Such as controlling the thickness of the charging, the speed of the mesh belt, the temperature, the carbon potential, etc. The movement of batch feeding can be monitored and controlled on a full screen. It can fully control the process program and can store 9999 processes. It can completely record the process parameters (part number, material, temperature, carbon potential, etc.) detected in the operation of the equipment and send it to the computer for processing and storage. It can be accessed and printed at any time. Records can be stored for ten years. Password layered control, fully layered. Contains the new furnace heating program, the shutdown heating program can effectively execute the heating process, etc.
1.2 High-quality heat treatment
The mass dispersion rate is zero, and the heat treatment distortion is zero. Quality control measures: feeding control system: weight, quantity and uniformity are controllable. Realize the popularization and adoption of tipping bucket, suction cup, tape, stepped and vibrating material systems. The feeding rhythm is automatically controlled, and the frequency conversion speed is adjusted. Part orientation is automatically arranged. Real-time monitoring of feeding thickness. Provide guarantee for the accurate execution of the heat treatment process from the source.
Equipment temperature control: furnace temperature stability ±1℃, furnace temperature uniformity ±10℃, cold treatment temperature uniformity ±5℃, switch-type temperature control will be eliminated.
Furnace atmosphere control: The furnace atmosphere uniformity is 0.05% oxygen probe, carbon removal air pump, carbon potential controller, furnace gas regulator and reliable coordination on the mesh belt furnace. Suitable for nitrogen methanol atmosphere. Methanol acetone (toluene) atmosphere, endothermic atmosphere, exothermic atmosphere, etc. The development of the combined multi-component carbon potential control technology of oxygen probe and infrared instrument and the emergence of other new carbon potential control technologies can not only improve the accuracy and stability of carbon potential control, but also better adapt to the atmosphere prepared by various gas sources . The carbon potential control technology of the second zone of the double oxygen probe further optimizes the quality control of carburizing and carbonitriding layers. The appearance of the continuous mesh belt furnace water agent quenching device to eliminate water vapor stabilizes the furnace atmosphere and ensures the carbon potential control accuracy. The new development of methanol gasification and cracking technology and the widespread adoption of stirring fans in the furnace have further improved the uniformity of the atmosphere in the furnace. The furnace shell sealing welding method not only saves energy, but also is conducive to the long-term stability of the atmosphere in the furnace.
Quenching tank control: In the aspect of ensuring the uniformity of workpiece hardness and reducing the deformation of parts, it has developed from simply reducing the cooling rate in the past to improving the uniformity of cooling. The quenching tank is equipped with a powerful stirrer with adjustable speed, paying attention to the flow field of the quenching tank and emphasizing quenching. Bath temperature uniformity. The temperature of the quenching tank is controllable. The computer cooling medium performance tester is also accepted by many users.
Heat treatment distortion control; use quenching furnace hot zone lengthening to remove stress. A fully enclosed quenching oil tank with thermal insulation and controllable classification is adopted. Quenching medium temperature uniformity 5 ℃. Anti-collision design of quenching tank and hoist blanking system. In order to reduce the amount of retained austenite in the bearing parts and control the slight deformation of the bearing after processing, it will be popular to add a cold treatment device after quenching in the mesh belt furnace production line.
1.3 Low-cost heat treatment
In the 21st century, with my country's entry into WTO, Chinese enterprises will be in the environment of international market competition, and the market will urgently need cheap and high-quality heat treatment equipment. And inexpensive heat treatment equipment will be low-cost heat treatment equipment rather than low-priced heat treatment equipment. The cost of heat treatment equipment consists of five parts: equipment procurement fee, equipment operation fee, equipment maintenance fee, equipment 4T labor fee, and heat treatment failure treatment fee.
Usually, the equipment procurement fee only accounts for 5-10% of the total equipment cost. To this end, equipment manufacturers will not strive to provide low-cost heat treatment equipment, but strive to provide low-cost heat treatment equipment.
For this reason, the mesh belt furnace designed and manufactured according to the engineering theory of RMs (reliability, maintainability, and supportability) is very popular.
Furnace type selection: The design begins with the selection of the correct choice of furnace type with muffle or without muffle.
Material selection of heat-resistant steel: It is high-quality Fe-Cr-Ni, Fe-Ni-Cr, Ni-based alloy material, and the material is reasonably selected according to the working temperature range of the furnace and the heat treatment process. Thereby, the actual life extension and the performance-price ratio tend to be more rationalized. The life of the muffle can reach 2-5 years, the mesh belt is 2-4 years, the idler is 5-10 years, the radiant tube is 2-4 years, and the fan is 5-10 years.
Material selection of instruments and electrical appliances: PLC programmable controllers with high reliability, SRC heating modules, self-adaptive digital display temperature control meters, and carbon control instruments are widely used, which can achieve trouble-free operation throughout the life cycle of the equipment.
Sensing element selection: The life of the atmosphere control oxygen probe is 1 year, the carbon potential control accuracy is ±0.05%, the life of the thermocouple is more than 5 years, and the control accuracy is ±0.05%. Bricks, ultra-light insulation board, refractory cotton, 5 years life.
Common defect prevention device: prevent parts from knocking and bumping the buffer pad; prevent parts from popping out of the scattered baffle; prevent parts from popping out and jam the torque limiter of the transmission mechanism; preventing parts from sticking. Add; a mountain-type and drum-type drying device that prevents the parts from being difficult to drain. Increase and lengthen the tempering furnace to ensure high uniformity of hardness.