JP2003531960A - Method and apparatus for heat treatment of steel wire - Google Patents

Abstract

(57) The present invention comprises the steps of raising the temperature of at least one wire to be treated to the austenitizing temperature of steel, and allowing the wire to remain in the metal mass of the at least one wire for an isothermal period. Maintaining said temperature and causing at least partial dissolution of carbides present in the steel during said isothermal period. The method of the present invention comprises forming a fluidized bed by passing a fluidizing agent through the fluidizable granules, heating the fluidized bed, and heating the at least one metal wire to be treated. Moving the fluidized bed in one direction to cause at least the increase in temperature, wherein the heating is at least to some extent substantially tangential to the average top surface of the fluidized bed. Obtained by at least one fluidized bed heating performed.

Description

Detailed Description of the Invention

TECHNICAL FIELD The present invention relates to the step of raising the temperature of at least one wire to be treated to the austenitizing temperature of steel and the isothermal period in the metal mass of said at least one wire. Maintaining the temperature for a period of time and causing at least partial dissolution of the carbides present in the steel during the isothermal period. The invention also relates to a device for implementing this method.

BACKGROUND OF THE INVENTION Conventionally, in wire patenting, heating of a wire or layer of wires is performed either in an open flame furnace or in a tube furnace without the aid of a fluidized bed. In the case of non-alloyed steels, the heating is generally carried out in an open-hearth furnace in which the atmosphere obtained by the combustion of gases and oxidants is adjusted as follows: i. In order to oxidize the product in order to burn residues of various properties which may be located at its surface, b) to produce a reduction on the product when it is subjected to an allotropic conversion step. Adjusted to prevent surface oxidation and decarburization.

In the case of alloy steel, a specific surface condition is generally required. Therefore, the product is heated by the heat dissipation or radiant tubes through which the protective gas passes, and a perfect surface condition of the product can be maintained throughout the heating stage.

In both cases, the heating time is relatively long, given the low heat transfer coefficient, due to convection in the case of open-hearth furnaces and pure heat radiation in the case of tube furnaces.

The furnace length required to heat the wire to an austenitizing temperature, eg, about 950 ° C., is large enough to impair the next step and if the furnace geometry is acceptable to the furnace user. If it is attempted to maintain within these limits, the isothermal period ("soaking") of the wire in the metal mass may be for only a short time (usually a few seconds). As a result, during the heating of the wire, the dissolution of cementite existing at the joints of the austenite grains becomes insufficient.

Further, wire furnaces using fluidized beds have been known for several years,
Applicants in particular already market such furnaces for the diffusion of Cu-Zn coatings in steel wires.

The Applicant has stated that it is possible to obtain good heat exchange between the heated particles of the fluidized bed which are in some way applied to the surface of the wire moving in the fluidized bed and the wire itself. I actually discovered that (for this, West German Patent Application Publication No. 36
23890 specification).

The method as described above is also described in Japanese Patent No. 2623004.
The heating of the fluidized bed is carried out by a fluidizing agent consisting of a flue gas obtained by combustion of combustion gases in air, which fluidizing agent is injected through the perforated lance into the bottom of the fluidized bed and these Perforated lances are extremely sophisticated to prevent particles in the fluidized bed from entering the lance. According to another mode, the fluidizing agent is air and the heat source located outside the fluidized bed is formed by a burner, which is arranged above the fluidized bed and vertically applies a flame or hot gas to the fluidized bed. .

Using the method described in this conventional patent document, 477 ° C. to 550 ° C. in the fluidized bed.
Only moderate temperatures of ° C can be achieved. In the first form, this is constrained by the very complex lances that supply the fluidizing agent to the fluidized bed, which can withstand the attack of excessively hot flue gases. Instead, there is a risk that it will have to be replaced on a regular basis. If heating is carried out vertically from above, this is not very efficient and has the disadvantage that in particular the temperature uniformity of the fluidized bed is impaired. The reason for this is that the burners used each impact the fluidized bed differently from each other, resulting in the very narrow surfaces of the fluidized bed becoming very hot,
It is clear that the adjacent part will be quite modest, which should be avoided in order to obtain proper handling of the wire.

[0010] Further, a fluidized fluid which is non-flammable when introduced into a fluidized bed, but becomes flammable when the temperature thereof rises is heated by combustion in a furnace or on the surface of the furnace. Floors are known (for example Reynoldson RW, Anwendung
von gasbeheizten Wirbelbetten zur Warmebehandlung von Metallen, in Hart
enei-Technischen Mitteilungen, Vol. 37, (1982), Munich, p. 109-119; Pate
nt abstracts of Japan Vol. 015, No 231 (that is, JP-A-3-72036))
. These heating methods have the disadvantage of being dangerous. This is because these heating methods actually pose the danger of an explosion and create an intense flame directed upwards. Such heating methods do not allow for controlling the heating uniformity of the part of the fluidized bed in which the object to be heated is located.

Fluidized beds housed in small diameter vessels and obtained with non-flammable fluidizing agents are also known. These fluidized beds are heated by surface injection of a combustion mixture by a burner for the purpose of heat treating large size and heavy metal parts which remain stationary throughout the treatment period which may last up to 30 minutes (this about,
(See the Reynoldson RW paper above).

The object of the present invention is to provide a solution for furnaces that are often large, especially those used for austenitizing steel wire, while at the same time as or better than conventional wire treatment. Achieving quality and allowing processing during continuous movement of the wire.

Another object of the present invention is to enable the fluidized bed with good energy efficiency to allow rapid and uniform heating of the wire to be treated, which is much longer than the isothermal period currently obtained. The purpose is to allow an isothermal period within the mass so that it does not adversely affect the overall size of the equipment.

DISCLOSURE OF THE INVENTION The above-mentioned problems are solved by the method of heat treatment of steel wire mentioned at the outset, which forms a fluidized bed by passing a fluidizing agent into a fluidizable granulate. Process,
The method further comprises the steps of heating the fluidized bed and causing at least one metal wire to be treated to move in one direction through the heated fluidized bed resulting in at least an increase in temperature. It is characterized in that it is obtained, at least in part, by at least one fluidized bed heating substantially tangentially to the average top surface of the fluidized bed.

As is known, a fluidized bed is suspended by the entrainment of a fluidizing agent, usually gas, and is formed by solid particles which pass through the fluidized bed from its bottom to its top. During this movement, the fluidizing agent carries the particles upwards, some of which are released in the form of higher waves or ridges than others. Therefore, in the lateral part of the fluidized bed, a top band is obtained during a considerable amount of exercise, whose top surface is constantly changing in height,
The top band represents a portion of the fluidized bed that is less dense with respect to particles.

Thus, the term average top of the fluidized bed means the surface located at the average height between the peaks and troughs of the waves present at the top of the fluidized bed. It is necessary to understand according to the present invention.

By the tangential heating of the average top surface, the particles of the fluidized bed located at the average top surface in a state where the density is not so high and is largely dispersed are heated to an extremely high temperature close to an incandescent state. Can be heated. The particles thus heated significantly transfer heat to other particles in contact with the wire, thus providing optimal heat exchange at a rate not attainable with prior art teachings. Furthermore, tangential heating is independent of the superplasticizer, and the perforated lance that spouts the superplasticizer is not attacked by flue gas heated to excessive temperatures.

Assuming that the heat transfer coefficient of the heated fluidized bed according to the present invention is excellent,
The heating temperature of the wire at which the austenitization of the wire occurs can be dramatically reduced, thus avoiding the expense of the equipment to a commercially unacceptable level and yet to make it unusable. It is now possible to achieve a period of time at which the austenitizing temperature is sufficient to obtain a complete dissolution of the Fe carbide in the steel wire. In addition, this embodiment allows the installation to be divided into two units, one being a relatively short one in the form of a fluidized bed furnace and the other a simple means, for example an electric heating element, It consists of a radiant type gas burner, a fluidizer recirculated from the elongated furnace and / or a simple isolated tube or chamber through which the wire passes while being maintained at a constant temperature by a second fluidized bed.

According to an embodiment of the invention, the at least one tangential heating is directed transverse to the moving direction of the at least one metal wire to be heated. The lateral and tangential orientation of the heating of the fluidized bed allows for the uniform heating of suspended particles in the fluidized bed over the width and length of the fluidized bed. , Enables uniform heating of the wire passing through the furnace.

According to an advantageous embodiment of the invention, the at least one tangential heating consists of jetting at least one flame and / or jet of fume tangentially to the mean top surface of the fluidized bed. . By such a method, the burner directly heats the particles of the fluidized bed without the need for hot combustion gases to pass through the perforated tube, which is vulnerable under these conditions. This structure is simple and highly effective.

According to a particular embodiment of the invention, the at least one tangential heating consists of a heat exchange between the heating medium and the fluidized bed via at least one tube, the at least one tube comprising: Located tangentially to the average top surface of the fluidized bed, the heating medium flows through the tubes. Thus, the alloy steel wire can be heated effectively and quickly without contacting the flue gas. The heat exchange takes place in a surprising way between a simple non-perforated tube through which the heating medium passes and the less dense particles of the fluidized bed sweeping the walls of the tube under heating.

According to an improved embodiment of the invention, the step of pumping the fluidized granulate at least once above the fluidized bed and a jet of this granulate towards the fluidized bed in a direction opposite to the direction of movement. Further comprising the step of driving, wherein the at least one tangential heating is at least partially performed by the driven jet of particles. Particles of the fluidized bed tend to be entrained as the wire passes through the fluidized bed by mechanical means,
It is necessary to recognize that this will move the particles from the entrance of the equipment towards the exit. The present invention not only eliminates this inconvenience, but also allows this pumping to be utilized to increase the efficiency of tangential heating. The reason for this is that the pumping drives the particulates in the form of rain to a height higher than the top of the fluidized bed and to the middle of the fluidized bed, which causes the above-mentioned average top face of the fluidized bed to the top of the fluidized bed. It is effective in raising higher than.

As a result, the burner head of the present invention can also be placed at a high height. In this case, the burner head can be placed in a particle-free area, so that this embodiment has a very low risk of fouling of the burner head by particles of the fluidized bed. Other features of the method of the invention are described in claims 1-9.

Further, according to the present invention, there is provided an apparatus for heat-treating a steel wire, which comprises an elongated heating furnace, a temperature maintaining zone, and at least one steel wire to be treated, which drives the furnace and the furnace. Means for passing in a direction transverse to the temperature maintenance zone, wherein at least one steel wire to be treated causes a temperature rise in the furnace up to the austenitizing temperature of the steel, A fluidized bed formed in the furnace by passing a fluidizing agent through the flowable granules in a device adapted to be maintained at temperature;
And means for heating the fluidized bed having at least heating means for producing heating substantially tangentially to the average top surface of the fluidized bed. Other features of the device of the invention are described in claims 10-17.

Other features of the invention will become apparent from the following non-limiting description of several exemplary embodiments of the device of the invention with reference to the accompanying drawings. BEST MODE FOR CARRYING OUT THE INVENTION In the drawings, the same or similar elements are denoted by the same reference numerals.

FIG. 1 is a cross-sectional view of an elongated furnace 1 containing a fluidized bed 2. The fluidized bed 2 is formed by relatively finely divided particles made of a material which is heat resistant and preferably inert to the wire to be heated. It is possible to use particles of silica, zirconia, alumina or other refractory materials with good compatibility in transferring heat to the body in contact with the particles. In particular, alumina sand or zircon sand having a particle size measurement value of F90 according to the 1984 FEPA42F standard can be mentioned.

A fluidizing agent, for example air, nitrogen or ammonia, is introduced by means of a perforated lance 3 at high pressure, in the present case at room temperature into the bottom of the fluidized bed. Any protective gas carefully selected according to the properties of the steel can be used for this purpose. The fluidizing agent, by virtue of its pressure and flow rate, carries the particles upwards from the fluidized bed and brings them into suspension. This floating state of the vortex type appears at the top of the fluidized bed 2 by forming waves, the average top surface of the fluidized bed being shown by the dash-dotted line 4.

It should be noted that the superplasticizer does not burn under the conditions of the method of the present invention. At cold or room temperature, the fluidizing agent exerts no stress on the lance that expels it into the fluidized bed, so the useful life of the lance is comparable to prior art lances that both fluidize and heat the fluidized bed. Very long compared to.

The very hot fluidizing agent after passing through the fluidized bed is then exhausted 5 (see FIG. 5).
Through to the top of the furnace.

In the illustrated embodiment, the speed at which one layer of wire 6 is calculated according to a constant determined by manufacturing requirements and requirements regarding the capacity of the production line, following the length of the furnace perpendicular to the plane of the drawing. To go through the furnace. This constant is equal to the product of the diameter of the wire in mm and the speed of the wire in m / min. Therefore, the thinner the wire, the faster the movement speed, and vice versa. It should be noted that movement of a single wire or movements of several kinds of wires of different diameters or movements of several overlapping layers at a time can be used in the furnace at one time.

As shown in FIG. 1, the fluidized bed heating means consists of several burners 7 (see also FIG. 4), which in this embodiment are on each side of the layer of wire to be heated. It is provided and causes a flame or fume to be emitted in a direction transverse to the direction of movement of the wire. The flames or fumes are jetted especially tangentially to the mean top face 4 of the fluidized bed and directly heat the particles suspended in the strip of the fluidized bed, in which the density of the particles is low and thus the particles are almost decarburized. Easily heat up to temperature. In the embodiment shown, it is clear that it is possible to place the burner at a slight tilt with respect to this flame or fume, if the so-called tangential direction of the flame or fume is exactly coincident with the surface 4 shown. Is. Provided that sufficient heating is always available on the surface of the fluidized bed and that the wire is not attacked by flames or fumes.

The burner flames and fumes obtained at the outlet of the burner can be fuel and oxidants such as combustible gases or liquids such as CH ₄ , fuel oil, etc. and oxygen-enriched or unenriched air, or industrially. It is obtained in the usual way due to the combustion of oxygen, which is considered pure. The resulting flue gas is then recovered by the exhaust pipe 5 at the same time as the heated fluidizing agent.

As is apparent from FIG. 4, the burners are arranged alternating from left to right of the layers of wire, with the flame and the entrained jet of very hot combustion gases traversing across the width of the furnace. Extending in the direction. This configuration has the advantage that it allows a very uniform heating of the fluidized bed and thus of the wire to be treated.

In the embodiment shown in FIG. 2, the wires to be heated are not allowed to come into contact with the combustion gases in order to leave their surface condition intact. Heating of the fluidized bed also occurs tangentially to the mean top surface 4 of the fluidized bed, but also by the non-perforated tube
Rubbed by the wave of particles in the fluidized bed, this non-perforated tube heats up to a high temperature. The combustion gases flow out through the outlet pipe 9 and these combustion gases can be recovered through such outlet pipe.

The embodiment shown in FIG. 3 is of the same form as the embodiment shown in FIG. However, in this embodiment, the chamber 10 is provided under the fluidized bed in communication with the protruding lance 3. One or more burners 11 are arranged in this chamber, which make it possible to obtain moderately higher temperatures of fume above room temperature, for example hot fumes of about 400-500 ° C., under which temperature the fumes are still lance 3. Don't attack too much. This embodiment can further increase the effectiveness of heating the fluidized bed. Of course, it is also possible to provide the structure with an open-fired furnace configuration as shown in FIG.

The wire treated in the furnace according to the invention is, for example, a steel wire which is subjected to the patenting method. The patenting method is a well known method in the wire drawing industry and first of all the temperature of a layer made of one wire or a plurality of metallic wires is obtained to convert ferrite and pearlite or pearlite and cementite to austenite. And the step of raising the level to such a level.

Next, a process called isothermal tempering is carried out to reconvert the austenite (previously obtained by heating) into a fine pearlite state, which has good mechanical properties, and in particular wire drawing. Try to get good compatibility with.

During the heating process of the wire, it is necessary to achieve a temperature of about 950 ° C. in order to obtain austenitizing of the steel. However, before proceeding to tempering, it is preferred to dissolve the carbides present at the joints of the austenite grains by means of an isothermal period in the metal mass called "soaking".

As shown in FIG. 5, in one example of the device of the present invention, it would be possible to provide two separate units, a heating unit 1 and an isothermal unit 12.

The heating unit consists of a furnace 1 with a fluidized bed 2 as described above, which is relatively short, assuming that the heat transfer coefficient of this type of furnace is excellent. May be. The wire 6 passes continuously through this furnace, the length of which is, for example, 5-6.
m. At the bottom of the furnace, a chamber 10 of the type shown schematically in FIG. 3 is arranged to allow preheating of the superplasticizer. The temperature of the heated fluidized sand of the present invention may advantageously reach about 1,000 ° C.

The wire 6 exits the furnace 1 at a temperature of about 950 ° C. and then passes through the isothermal unit 12 by means of a closed hopper 13. The unit 12 comprises, from a thermal point of view, a completely insulated chamber or tube. In this regard, it suffices to maintain the resulting wire temperature of 950 ° C. and to maintain heat exchange so that no heating is required. In the example shown, this temperature maintenance is achieved by recirculating the combustion gases from the unit 1 into the exhaust pipe 5. The released combustion gas is filtered by a means such as a cyclone 1
4 to the unit 12 by means of a pump 15 which carries the filtered gas, which is still hot or is partially heated in a complementary manner. The purpose is to maintain the temperature of the wire. The melting of the carbide (cementite) is carried out in the unit 12, the length of which may be about 4 m, in which the wire is moving and sufficient to achieve the melting of the carbide. Keep it that way for hours. As the wire exits the unit 12, it reaches a tempering device 16, only a portion of which is shown. Therefore, the overall length of the device in this example is perfectly acceptable in terms of dimensions of about 9-10 m.

7 and 8 show another embodiment in which a pumping device 17 for suppressing the movement of particles in the fluidized bed from the furnace inlet to the outlet is provided. In fact, the particles are mechanically driven by the movement of the wire.

These pumping devices 17 are, in the example shown, pipes 18 arranged substantially vertically.
The tube 18 is connected at its bottom to a connecting cone 19. This is advantageously arranged above the perforated lance 3. The tube 18 is connected at its top to a spray nozzle 12, which is directed in the direction opposite to the direction of movement of the wire 6 to be treated. Advantageously, the spray nozzle 20 is also oriented obliquely towards the central part of the furnace, as can be seen in FIG. In this embodiment, the small holes provided in the lance 3 are arranged downward.

The fluidized bed particles and fluidizing agent flow into the collection cone. In this case, assuming that the mass of particles in the tube has an apparent density that is much less than the apparent density of the fluidized bed, the mass is ejected higher than the top of the fluidized bed, in which case the spray nozzle A jet 22 of particles is sent to the rear of the fluidized bed and towards its center, which suppresses movement of the particles in the direction of movement of the wire. As can be seen, this pumping does not require additional expenditure of energy in the illustrated embodiment.

The effect of these jets is to raise the average top surface of the fluidized bed, which in the example shown is at the height of the dash-dotted line 4 '. As can be seen in Figure 7, this height position is higher than the wave crests of the fluidized bed. Therefore, as is apparent from FIGS. 7 and 8, the heating by the burner 7, according to the invention, now occurs tangentially to this mean top surface 4 ′, which means that the mean top surface is responsible for the particles emitted from the burner. It has been pulled up to pass.

The tangential heating thus obtained is particularly effective. In addition, this has the advantage that the head of the burner 7 is located outside the reach of the particles ejected towards the center of the furnace. It is thus advantageous because fouling of the burner head can be avoided.

Experimental examples are given below as non-limiting examples in order to explain the invention in more detail. Experimental Example 1 A eutectic steel wire having a diameter of 3 mm was introduced into a fluidized bed furnace equipped according to the present invention, and the DV constant (wire diameter (mm) x moving speed (m / min) of this fluidized bed furnace was introduced. ))
Is 36. The fluidized bed has a flow measurement value of 106 to 150 μm of Al 2 O 3 −.
Composed of F90. This fluidized bed has a minimum pressure of 600mmH2O and a flow rate of 64N.
m3 / h. It is kept floating by m2 of fluidizing gas, in this case air. Fluidizing gas is introduced at the room temperature from the bottom of the fluidized bed.

The burner ejects fumes generated by the combustion of gas and combustion air in the tangential direction of the average top surface of the fluidized bed to heat the fluidized bed particles to almost the decarburization temperature, and the average temperature is about 1. A fluidized bed at 000 ° C. is obtained. The burner fume is in direct contact with the fluidized bed.

As can be seen from the curve A in the graph of FIG. 6, the wire reaches a temperature of 950 ° C. for a maximum of 30 seconds after about 20 seconds of travel, ie, the length of the fluidized bed furnace of the invention. With the DV constant selected as above, it can be limited to a value of about 5 m.

Even if the wire has a length of 4 m or more, which corresponds to a passage time of 20 seconds, the wire is
A temperature of 950 ° C. is maintained in the unit 12 so as to obtain the dissolution of the third cementite.

For comparison, the same wire was allowed to move through a high convection conventional open flame furnace (no fluidized bed was used). As you can see on curve B. In order to reach the austenitizing temperature, the wire has to be heated for about 50 seconds and the isothermal period in the metal mass is between 3 and 4 seconds in a furnace of the same length and the same DV constant. Only occurs, which is insufficient for obtaining good dissolution of the carbide (tertiary cementite).

Experimental Example 2 An XC70 type steel wire (0.76% C) was subjected to the same treatment conditions as in Experimental Example 1. The diameter of the wire was 1 mm and its DV constant was 36. Since the wire reached a temperature of 950 ° C. after moving for about 5 seconds, it is recommended to limit the length of the fluidized bed furnace to a value of 5 m or less. Even over a length of 4 m, which corresponds to a transit time of about 7 seconds, the wire is kept at a temperature of 950 ° C. for melting the third cementite.

Experimental Example 3 XC70 type steel wire (0.76% C) was subjected to the same treatment conditions as in Experimental Example 1. The wire diameter was 5 mm and its DV constant was 36. The wire reached a temperature of 950 ° C. after about 40-50 seconds of travel, so the length of the fluidized bed furnace should be limited to a value of about 5.5 m. The wire is 950 ° C even if it is longer than 4m, which is equivalent to a transit time of about 35 seconds
Maintained at the temperature condition of.

It is to be understood that the present invention is in no way limited to the embodiments described above, and that many modifications of the invention may be envisaged without departing from the scope of the invention as claimed. Is.

[Brief description of drawings]

[Figure 1]   It is a longitudinal cross-sectional view of one embodiment of the fluidized bed furnace of the present invention.

[Fig. 2]   It is a longitudinal cross-sectional view of another embodiment of the fluidized bed furnace of the present invention.

[Figure 3]   It is a longitudinal cross-sectional view of another modified embodiment of the fluidized bed furnace of the present invention.

[Figure 4]   It is a top view of the furnace shown in FIG.

FIG. 5 shows a device consisting of two consecutive units, one heating the wire and the other maintaining the temperature.

FIG. 6 is a graph showing variations in temperature of a wire passing through a furnace as a function of time.

[Figure 7]   It is a cross-sectional view of a fourth embodiment of the fluidized bed furnace of the present invention.

[Figure 8]   It is a longitudinal cross-sectional view of another modified embodiment of the fluidized bed furnace of the present invention.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CO, CR, CU, CZ, DE , DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, I S, JP, KE, KG, KP, KR, KZ, LC, LK , LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, P T, RO, RU, SD, SE, SG, SI, SK, SL , TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW F-term (reference) 4K043 AA02 CA07 DA03 EA04 FA03                       GA04 GA05                 4K046 AA04 HA02 JA02 JC06 JD05

Claims (17)

[Claims] 1. Increasing the temperature of at least one wire to be treated to the austenitizing temperature of steel; maintaining the wire in said metal mass of said at least one wire at said temperature for an isothermal period. A step of causing at least partial dissolution of carbides present in the steel during the isothermalization period, and a method of heat treating a steel wire comprising: flowing a fluidizing agent into a fluidizable granule; Shaping the bed, heating the fluidized bed, causing at least the temperature rise by causing the at least one metal wire to be treated to move in one direction through the heated fluidized bed And wherein the heating is obtained, at least in part, by at least one fluid bed heating substantially tangential to the mean top surface of the fluid bed. How to with. 2. The method of claim 1, wherein the at least one tangential heating is directed transverse to the direction of movement of the at least one metal wire to be heated. 3. The at least one tangential heating comprises jetting at least one flame and / or fume jet tangentially to the mean top surface of the fluidized bed. Or the method described in 2. 4. The at least one tangential heating consists of heat exchange between a heating medium and a fluidized bed through at least one tube, the at least one tube being the mean top surface of the fluidized bed. 3. The method of claim 1 or 2, wherein the heating medium is tangentially arranged and the heating medium flows through the tube. 5. The method further comprises pumping the fluidized granules above the fluidized bed at least once and driving a jet of the granules toward the fluidized bed in a direction opposite to the direction of movement. The method according to any one of claims 1 to 4, wherein the at least one tangential heating is at least partly performed by a jet of driven granules. 6. The fluidizing agent exhibits nonflammability during the performance of the method,   The method according to any one of claims 1 to 5, characterized in that: 7. The method of claim 1, wherein the step of heating the fluidized bed further comprises the step of heating the fluidizing agent before it passes through the flowable granules. The method according to any one of items. 8. The method according to claim 1, wherein a temperature of the fluidized bed of 950 ° C. or higher, preferably 1000 ° C. or higher can be achieved by heating in a time of 30 seconds or less. the method of. 9. The method according to claim 1, further comprising maintaining the at least one wire at an austenitizing temperature inside the fluidized bed and / or outside the fluidized bed. 9. The method according to any one of 8 to 8. 10. An apparatus for heat-treating a steel wire, comprising: an elongated heating furnace (1); a temperature maintenance zone (12); driving at least one steel wire to be treated, which comprises a furnace and Means for passing in a direction transverse to the temperature maintenance zone, wherein the at least one steel wire to be treated causes a temperature rise in the furnace up to the austenitizing temperature of the steel, A device adapted to be maintained at this temperature, wherein a fluidized bed (2) formed in a heating furnace by passing a fluidizing agent through a flowable granular material, and an average top surface of the fluidized bed A fluidized bed heating means having at least heating means for producing heating substantially tangentially. 11. The tangential heating means comprises at least one burner (7) for ejecting flames and / or fumes tangentially of said mean top surface of the fluidized bed. Equipment. 12. Several wires, preferably alternating on each side of the moving wire or wires (6), which cause the flame and / or fumes to be ejected transversely to the direction of movement of the wires. 11. Device according to claim 10, characterized in that it comprises a burner (7). 13. The tangential heating means comprises a tube (8) arranged tangential to the mean top surface (4) of the fluidized bed (2) and transverse to the direction of movement of the wire, 11. The device of claim 10, wherein the medium passes through the tube. 14. At least one particulate matter pumping device for pumping the particulate matter above the fluidized bed and driving it in the form of a jet towards the fluidized bed in a direction opposite to said direction of movement, 14. A device as claimed in any one of claims 10 to 13, characterized in that the heating means causes the tangential heating via a jet of particulate matter driven by at least one of the pumping devices. 15. Further comprising means (11) for preheating the fluidizing agent,   Device according to any one of claims 10 to 14, characterized in that 16. A short elongated furnace (1) for rapidly reaching the austenitizing temperature of the at least one wire to be heated, and an insulation chamber (12) provided next to the furnace, The device according to any one of claims 10 to 15, wherein the wire is maintained at the predetermined maximum temperature by a temperature maintaining means (5, 14, 15) in the heat insulating chamber. 17. The temperature maintaining means is an electric heating element, a radiant type gas burner,
17. Device according to claim 16, characterized in that it is a means (5, 14, 15) for recirculating the fluidizing agent exiting the elongated furnace and / or a second fluidized bed.