In the conditions of heat treatment, materials acquire new properties and qualities required at different technological stages of production. In particular, metal billets change their condition, gain new indicators of strength, hardness and stability. To ensure the thermal effect, special thermal furnaces are involved, due to which annealing, hardening, tempering, and other operations are performed.
General arrangement of heat treatment units
The frame construction of this equipment is formed by a thick-walled case made on the basis of heat-resistant steel alloys that are not subject to chemical destruction processes. Heating is provided by burners that generate heat during fuel combustion. These are typical incinerators in heating and thermal furnaces, due to which the air temperature rises to the desired values. Further, the combustion products are sent to the insulated chimney outside or to a special collector for the subsequent use of gases already in other technological operations. The designs of high-temperature units can be lined with refractory coatings in order to reduce heat loss and harmful effects on the walls of the housing.
Feed system
In the continuous production mode, one of the key factors for the efficient implementation of the processing process is to maintain the optimal rate of movement of new workpieces into the work area. Traditionally, this problem is solved by conveyor and roller mechanisms connected to an automatic drive. However, even a high degree of mechanization is not always effective in the construction of large-sized rolling mills.
Another complication of using long pallets with a movable coating is the need to connect water-cooled elements, which should regulate the temperature regime of the workpiece during delivery. Therefore, as an alternative, a transport system with a revolving revolving drum is used today. In this configuration, the thermal furnaces provide two-sided uniform heating of the workpieces with minimal delays during transportation. Also, heating up time is reduced and the amount of fumes that negatively affects the structure of the metal is minimized. However, the air cooling systems of the drum shaft are sometimes connected to such installations, which requires certain technical and organizational costs.
Chamber furnaces
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 using a special crane on a suspended structure. In parallel with the transportation process, the burner is regulated, which turns on after the damper has lowered and closed the target material installed in the chamber. Further, already in the course of fuel combustion, gas waste is discharged through chimneys integrated into the side walls. Recuperators can also be provided in the design of thermal chamber furnaces, due to which part of the heat from the gas mixtures is returned to the processing zone. Models for complex in-line processing can contain up to eight chambers with their own pallets. Moreover, each operation is carried out in a protective gas environment, which is especially important in working with annealing of aluminum alloys.
Bell furnaces
This is a unit with cyclic action, designed for heat treatment of metal strips in rolls, as well as wire riots. The design is provided with an inner cap that protects the workpieces from negative oxidation processes. Outside, the walls of the structure have a brick lining, where the communications of electric heaters and a burner are also mounted. To increase the tightness of bell-type types of thermal furnaces, sand closures are used. As for the cyclic action, it is provided by an internal fan. This device promotes the active circulation of the protective gas under the hood at different stages of heating from 650 to 800 ° C. The combustion products are moved between the heating elements with a cap and through the injector are discharged into chimneys or a special collection.
Conveyor ovens
Models of industrial heating equipment provided with a chain internal conveyor. As mentioned above, on moving pallets, the process of transporting workpieces between technological processing sections is carried out. Despite the technological difficulties of organizing the conveyor method of operating thermal furnaces, devices of this type make it possible to provide a direct countercurrent mode of operation, which is advantageous for large volumes of equipment loading in the stream. A special principle of the direction of combustion products is also noted. The optimum temperature of the workpieces can be maintained due to the parallel movement of the exhaust gas flows. That is, products move in the same direction with hot gases through different channels, making heat transfer. As a result, due to passive heating of the material, energy costs for the main stages of heat treatment are reduced.
Broaching furnaces
The design is designed for continuous action in relation to the performance of thermal or chemical-thermal operations. A broaching furnace can have a tower and multi-story device - respectively, vertical and horizontal structures. The advantages of the first type include compact dimensions while maintaining a useful technological area and the possibility of processing workpieces with wavy coatings and surface irregularities. As for horizontal thermal furnaces of a long type, they effectively work with thick sheet metal without kinks. The equipment device 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
Monitoring and control of heating processes is carried out through operator panels with controllers, which collect data on the main indicators of equipment status. This system allows you to monitor the processing temperature, operation time, pressure in the working area and more. In gas thermal furnaces, particular attention is paid to the regulation of the burner function. The feed pressure of the combustible mixture, flame intensity indicators and fuel consumption control are also monitored.
Conclusion
Modern heat treatment processes are distinguished by technological complexity and high energy consumption. In conditions of large-scale production, these costs are covered by the possibility of organizing in-line operations at full capacity utilization. But even this format of operation of thermal furnaces can justify itself only under the condition of carefully calculated production logistics. It is important not to forget that the equipment under study works in conjunction 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.