RO132048A0 - Heat-treatment furnace with vibrating platform - Google Patents

Abstract

The invention relates to a heat-treatment furnace with vibrating platform for heating metal parts, in view of applying annealing, hardening, tempering or stress-relieving treatments, the furnace with vibrating platform reducing the heat-treatment duration, hence, the energy consumption. According to the invention, the furnace may be heated with gas or electric power and it is provided outside with a support (2) on which an electromagnetic vibrator (3) is fixed, either a linear one or an air-gap one, which is supplied with a current the frequency of which is adjustable within the range of 50...400 Hz, provided by the frequency converter (4), the vibrations being sent to the vibrating platform (7) on which the heat-treated parts (10) are placed, the vibrations leading to acceleration of the following processes: stress-relieving, recrystallization, allotropic transformation, dissolution of certain constituents, diffusion and self-diffusion.

Description

The invention relates to a "vibrating platform heat treatment furnace" used for heating products for the purpose of applying annealing, heating, recovery or stressing treatments. The invention achieves the reduction of the time of heat treatment and implicitly of the energy consumption.

In all the industrial fields in which metallic materials are processed various thermal treatments are applied in order to modify the microstructure and implicitly the properties of the products. The mechanisms of transformation of the microstructure that act on heating, maintaining and cooling the materials are based on diffusion and self-diffusion processes caused by the difference between the free energies of the constituent phases of the material. Free energy is a function that characterizes the state of a thermodynamic system in which atoms perform small oscillations around the nodes of the crystalline network. It is influenced by both temperature and pressure variation.

In classical thermal treatments, while maintaining the parts at high temperatures, the processes of tension relaxation, recrystallization, allotropic transformation, dissolution of some constituents, diffusion and self-diffusion, are carried out as an effect of increasing the amplitude of the oscillations of the atoms, and this is a consequence of the increase of the atoms. temperature, the pressure remaining constant.

According to the invention, in the parts subjected to the heating, vibrations are generated that propagate through the material in the form of elastic waves that produce variations of pressure throughout the volume of the parts. Through the synergy of the thermal field and that of the mechanical oscillations, the amplitude of the oscillations of the atoms increases, and in these conditions all the processes that take place during the heating and the maintenance are carried out at an increased speed. Under these conditions, the duration of heating and maintaining at the prescribed temperature can be substantially reduced. The energy consumption required to generate oscillations is small compared to the energy savings achieved by reducing the duration of the heat treatment.

The following are some inventions according to which during heating are used mechanical wave fields that are applied in order to influence the microstructure and the state of tension in the material:

- DE 102011114889 Al / 2013, Verfahren zur Verănderung der Gefugestruktur von Werkstoffen. The invention describes the principles of processes by which the microstructure and properties of metallic materials can be modified under the simultaneous influence of heating over the recrystallization temperature and of an electric current with a complex variation, under which forces are generated that influence the development of crystalline grains, in a way. specific.

The disadvantages of the invention consist in the fact that for the application of the claimed processes, special electronic equipment is required which ensures the generation of a current with a complex voltage variation, electric signal amplifiers, as well as electrical signal transmission systems, systems that must be protected against heating. According to the invention, only processes are claimed, without presenting examples of implementation and application of the proposed processes.

CN 204007109 U / 2014 Ultrasonic vibration activation assisting sintering chamber electric furnace. The invention relates to an electric furnace in which the semi-factories subjected to the operation of 2017 00134

06/03/2017 sintering are subjected to the action of an ultrasonic field in order to accelerate the sintering process. The disadvantage is the characteristics of the ultrasonic oscillations. At high frequencies, the amplitude of the oscillations of the particles that make up the material are small, so that the diffusion processes are influenced to a relatively small extent. In order to obtain significant effects, vibrations with the greatest acceleration are required, which in the ultrasonic field can be achieved only by increasing the power of the translator that generates the oscillations.

in the work [Abdul Ghani Al-Olabi; Residual stresses and heat treatments for metallic welded components, Doctoral thesis, Dublin City University, 1994], it is emphasized that amplitude and acceleration of oscillations are the determining factors in the processes of diffusion and reorganization of dislocations. Thus, the application of oscillations with high frequency and low amplitude is useful for accelerating the sintering operations, being prevented the risk of crushing of semi-factories composed of compacted powders. In the case of products with polycrystalline structure that are subjected to various heat treatments, low frequency excitation, below lkH, which causes oscillations with large amplitudes and accelerations is preferable, without the risk of causing inter-crystalline breaks.

- CN 1752223 A / 2006 Heating and vibrating stress removing method for metal material. The invention relates to a method of reducing the internal stresses of large welded constructions. The method consists of local heating at temperatures below 500 ° C, together with the vibration of the construction on a resonant frequency for a period of less than 30 minutes. The disadvantage of the method is that by local heating and vibration, the internal voltages are redistributed in a larger volume and thus their maximum value decreases, but throughout the construction a good part of the voltages are kept and are distributed evenly.

The object of the invention is to reduce the duration of heat treatments carried out in electric or gas heated ovens. According to the invention, while maintaining the recommended temperature, vibrations with adjustable frequency within the limits of 50 ... 400 Hz are generated in the parts subjected to the heat treatment, which ensures oscillations having accelerations of 2 ... 12 m / s ² . Through the synergy of the thermal field and the one of mechanical oscillations with amplitude and high accelerations, the diffusion processes are accelerated, so that the retention time is reduced to less than half compared to the time required to apply a heat treatment applied without vibration.

The invention can be applied to accelerate the following heat treatments:

Stress annealing (steel, cast iron T = 450 ... 600 ° C);

Recrystallization annealing (different T alloys> 0.4T _top [K]);

- Softening annealing - globularization (steel, T = A, ± 30 ° C);

Normal annealing (steel, T = A3 + 30 ° C);

- Normalization (steel, T = A3, A5 + 30 ° C);

- Homogenization annealing (steel, T - 950 ... 1200 ° C);

- Return (steel, T = 190 ... 600 ° C);

- aging (aluminum alloys, T = 180 ° C); heating for tempering (steel, T = A3 + 30 ° C).

The technical problems that the invention solves

Reduces energy consumption at heat treatment - processes are environmentally friendly;

to 2017 00134

03/06/2017

- The power consumption of the exciter and frequency converter is reduced;

- Increases productivity, reduces manufacturing costs;

By reducing the treatment time, the surface oxidation and decarburization is reduced;

- The frequency and power of the oscillations can be adjusted according to the mass of the load, so that the acceleration at the level of the parts is optimal, and in the area of the ceramic components of the oven, the influence of vibrations is minimal.

The thermal protection of the electromagnetic exciter is provided by a cooler through which water flows;

The vibration system can be applied to electric or gas heated ovens.

The following is an example of an embodiment of the invention with reference to Figure 1.

Fig.l "Heat treatment furnace with vibrating platform"

According to the invention, the heat treatment furnace with vibrating platform (1) is provided externally with a support (2) on which is fixed a linear electromagnetic vibrator or with air gap (3) which is supplied with an alternating current or pulses with adjustable frequency in limits 50 ... 400 Hz, provided by the frequency converter (4). The protection against heat transfer from the furnace to the vibrator is achieved by the chiller (5) through which water flows.

The vibrations produced by the electromagnetic vibrator are transmitted through the coupling rod (6) to the vibrating platform (7) which is placed through the ceramic balls (8) on the base plate (9) in which spherical chambers having a larger radius are executed. with 50 ... 60% compared to the radius of the ceramic balls. In these conditions, the parts (11) placed on the vibrating platform are transmitted vibrations which in a horizontal plane have a greater acceleration (a _x ), and in a vertical plane a lower acceleration (a _y ).

For ovens with a working temperature below 600 ° C, ceramic balls can be replaced with springs that provide free vibration of the vibrating platform, and the energy transmitted to the base plate is diminished.

The heat-resistant and vibro-absorbent plate (10) dampens the vertical component of the vibrations that are transmitted to the ceramic components of the oven, thus avoiding their degradation over time.

The module of programming, thermoregulation and control (12) ensures the operation of the oven according to the parameters imposed for the application of the heat treatment chosen.

Claims (4)

claims 1. Heat treatment furnace with vibrating platform, characterized in that it is provided externally with a support (2) on which is fixed a linear electromagnetic vibrator or with air gap (3) which is supplied with an alternating current or pulses with adjustable frequency. within the limits of 50 ... 400 Hz, provided by the frequency converter (4), the vibrations produced are transmitted through the coupling rod (6) to the vibrating platform (7) supported by means of the ceramic balls (8) on the base plate (9), so that the pieces (11) are subjected to the action of vibrations which have an average acceleration of 2 ... 12 m / s ² . 2. Heat treatment furnace with vibrating platform, according to claim 1, characterized in that the base plate (9) is made with spherical chambers having a radius greater than 50 ... 60% compared to the radius of the ceramic balls (8) , so that the parts (11) placed on the vibrating platform (7) are transmitted vibrations which in a horizontal plane have a greater acceleration (a _x ), and in a vertical plane a lower acceleration (a _y ). 3. Heat treatment furnace with vibrating platform, according to claims 1 and 2, characterized in that for ovens having a working temperature lower than 600 ° C, ceramic balls (8) can be replaced with springs that provide free vibration of the platform. vibrators (7). 4. Heat treatment furnace with vibrating platform, according to claims 1, 2 and 3, characterized in that the protection against the transmission of heat from the oven to the vibrator (3) is achieved by the cooler (5) through which water circulates, and the attenuation of the vibrations transmitted towards The components of the oven are provided by the heat-resistant and vibro-absorbent plate (10).