Under the conditions of heat treatment, materials acquire new properties and qualities required at different technological stages of production. In particular, metal blanks change their state, acquire new indicators of strength, hardness and stability. To ensure thermal effects, special thermal furnaces are used, due to which annealing, hardening, tempering and other operations are performed.
General arrangement of heat treatment units
The frame structure of this equipment is formed by a thick-walled body made of heat-resistant steel alloys that are not subject to chemical destruction processes. Heating is provided by burners that release heat during the combustion of fuel. These are typical combustion devices in heating and thermal furnaces, due to which the air temperature rises to the desired values. More products of combustionare sent to a heat-insulated chimney to the outside or to a special collector for subsequent use of gases in other technological operations. Designs of high-temperature units can be lined with refractory coatings in order to reduce heat loss and harmful effects on the vessel walls.
Material feeding system
In in-line production, one of the key factors in the efficient execution of the machining process is to maintain the optimal rate of movement of new workpieces into the work area. Traditionally, this problem is solved by means of conveyor and roller mechanisms connected to an automatic drive. However, even a high degree of mechanization is not always effective when constructing large rolling mills.
Another difficulty in using long movable floor pallets is the need to connect water-cooled elements that must regulate the temperature of the workpiece during delivery. Therefore, as an alternative today, a conveying system with a rotating drum of the turret type is used. In this configuration, thermal furnaces provide two-sided uniform heating of workpieces with minimal delays during transportation. It also reduces the time for warming up and minimizes the volume of waste, which negatively affects the structure of the metal. However, air cooling systems for the drum shaft are sometimes connected to such installations, which requires certain technical and organizational costs.
Chamberovens
This equipment is made with a movable and fixed pallet for the delivery of workpieces. The movement process can be provided by a special roller or wheelbase on rails. Workpieces with a large mass are moved with the help of a special crane along a suspended structure. In parallel with the transport process, the burner is regulated, which is switched on after the damper lowers and closes the target material installed in the chamber. Further, already during the combustion of fuel, gas waste is released through chimneys integrated into the side walls. In the device of thermal chamber furnaces, recuperators can also be provided, thanks to which part of the heat from gas mixtures is returned to the technological processing zone. Models for complex in-line processing can contain up to eight chambers with their own trays. Moreover, each operation is performed in a protective gas environment, which is especially important when working with annealing aluminum alloys.
Bell-type furnaces
This is a cycling unit designed for heat treatment of coiled metal strips as well as wire coils. The design is provided with an internal cap, which protects the blanks from negative oxidation processes. Outside, the walls of the structure have a brick lining, where communications of electric heaters and burners are also mounted. To increase the tightness of bell-shaped types of thermal furnace, sand gates are used. WhatAs far as cycling is concerned, it is provided by an internal fan. This device contributes to the active circulation of the protective gas under the bell at different stages of heating from 650 to 800 °C. The products of combustion move between the heating elements with a cap and are discharged through the injector into the chimneys or a special collector.
Conveyor ovens
Models of industrial heating equipment provided with chain internal conveyor. As mentioned above, moving pallets carry out the process of transporting workpieces between technological processing areas. Despite the technological difficulties of organizing a conveyor method of operation of thermal furnaces, devices of this type make it possible to provide a direct-countercurrent mode of operation, which is beneficial with large volumes of equipment loading in a stream. A special principle of the direction of combustion products is also noted. The optimal temperature of the workpieces can be maintained due to the parallel movement of the exhaust gas flows. That is, the products move in the same direction with hot gases through different channels, performing heat exchange. As a result, due to passive heating of the material, energy costs for the main stages of heat treatment are reduced.
Broach ovens
The design is calculated for permanent action in relation to the performance of thermal or chemical-thermal operations. A broaching furnace can have a tower and a multi-storey device - respectively, vertical and horizontal structures. To the benefitsThe first type includes compact dimensions while maintaining the usable technological area and the possibility of processing workpieces with wavy coatings and surface irregularities. As for the horizontal broaching type thermal furnaces, they effectively work with thick sheet metal without kinks. The device of the equipment has a special mechanism for unwinding rolled products, a device for automatic cutting of edges and an installer of a new strip in the fixing and gripping machine.
Heat treatment control system
Control and management of heating processes is carried out through operator consoles with controllers, which collect data on the main indicators of the state of the equipment. This system allows you to monitor the processing temperature, operation time, pressure in the working area, and more. In gas thermal ovens, special attention is paid to the regulation of the burner function. It also monitors the supply pressure of the combustible mixture, indicators of the intensity of the flame and control of the consumption of fuel materials.
Conclusion
Modern heat treatment processes are characterized by technological complexity and high energy consumption. In the conditions of large-scale production, these costs are covered by the possibility of organizing flow operations with full capacity utilization. But even such a format of operation of thermal furnaces can justify itself only if the production logistics are carefully calculated. It is important not to forget thatThe studied equipment works in combination with other technological processes. And this is not to mention the need to connect cooling and ventilation systems, the characteristics and arrangement of which will depend on the design capabilities of a particular workshop.
