CH702902A2 - Method and device for heating of elongated metal products. - Google Patents

Abstract

In a method for heating elongated products (1) of metal, in particular wires and tapes, the thermal energy for heating in a continuous process is transferred to the product (1). The thermal energy is generated by means of two different heat generation methods. In a first method, the thermal energy is transferred without contact via the jacket of the elongated product (1) and generated in the second method by electric current in the product (1) itself. The device has a continuous heating section (4) with transport means for the elongated product (1) and two partial sections (5, 6). The heating section (4) comprises in the first subsection (5) a first device (8) for generating thermal energy outside the product (1) and parallel thereto, arranged over the two subsections (5, 6), a second device (7) a directly on the product (1) acting electrical resistance heating.

Description

The invention relates to the field of continuous heating of elongate products made of metal, preferably wires and tapes, in a continuous process, in particular a method and its application and an apparatus and their use for the application of thermal energy to the elongated product according to the preamble of corresponding independent claims.

Methods and apparatus for continuous heating of elongated metal products, also called long material, are known for example in the manufacture and / or heat treatment of wires and tapes. The heating takes place for generating the processing temperature, for annealing solidified materials or for other thermal treatments. In the methods and devices used today, the heating of the elongate product is carried out in a continuous process. In each case only a partial area, or a portion of the product, e.g. a wire or a ribbon, heated. For example, so-called glow tubes are known, which are electrically heated and through which a wire or a band is pulled. Such glow tubes find e.g. during wire drawing use to softly anneal the wire between individual drawing stages or at the end of the drawing process. Glow pipes usually have a large length and allow only low speeds of the continuous elongate product. These passage speeds reach a maximum of 2 m / s for wires with a diameter of less than 3 mm. Therefore, such glow tubes can not be used in the same continuous process, also known as "in-line", with pulling devices or rolling devices for wires or belts, which allow significantly higher throughput speeds. This limitation is particularly true in direct cooperation with high-speed winders, with which the wire or the tape is wound on spools.

DE 2 015 702 A1 describes a heat treatment station for wire production, with which the continuous wire is soft annealed between individual drawing stages. The heat treatment station consists essentially of a tubular heat radiator in which infrared radiation concentrates on the continuously passing wire in the center and the wire is thereby heated. This device can be operated only with relatively low throughput speeds of the wire. Particularly in the case of wires from the areas of fine and ultrafine wires, in-line operation results in throughput speeds at which adequate heating would no longer be guaranteed. For in-line operation, the entire production line would have to be run more slowly, or the wire would have to be intermediately stored before and after the heat treatment station on intermediate coils, which in both cases would increase operating costs. Another disadvantage of this method is that the heating of the wire takes place via the jacket and therefore seen outside the cross-section higher temperatures than in the center of the wire. For thicker wires, the temperature on the outer jacket must be brought to a higher level in order to reach the desired temperature in the center of the wire.

From DE 2002 373 A1 a wire drawing device is known in which an annealing device is operated directly after the drawing devices in series and inline. The annealing device in this case has two contact rollers, via which current passed through the continuous wire and the portion of the wire, which lies between the two contact rollers, is heated by means of the electrical resistance. Such annealing devices are also called resistance annealing. Also heating devices of this type have the disadvantage that they allow only limited throughput speeds. In particular, in the production of fine wire with diameters in the range of about 0.01 mm - 0.1 mm, a direct cooperation with a high-speed winder, which winds up the finished wire, usually not possible because such winder work at higher speeds than when passing through the annealing device are possible. In most cases, therefore, the additional use of inexpensive intermediate winder is necessary. For the metals that are normally processed on such wire drawers, the electrical resistivity depends on the temperature of the wire and it increases significantly with increasing temperature and at the final temperatures which must be achieved here. In the first part of the part of the wire, which is located between the two contact rollers, the wire is still cold and has a low temperature, which is why the resistance and thus the heating power in this first part are low. The consequence of this is a large length of the heating section between the two contact rollers and a high power requirement. In order to reduce this disadvantage, solutions are known in practice in which the entire heating section is subdivided into sub-sections and each sub-section is assigned its own power supply. For this purpose, further contact rollers for transmitting the electrical energy are necessary within the heating section. These additional contact rollers have the disadvantage that they withdraw heat again from the wire and cool it. Therefore, the use of such systems for thin wires, for example less than 0.05 mm in diameter, not practical, since the cooling and thus the heat loss are too large.

In DE 10 100 829 C1 an induction annealing for heating a wire is described. The technology of such induction annealing is based on the principle of electrical transformers. In this device, the continuous wire is passed over contact rollers and a shorting wire loop is formed. This shorting wire loop forms a secondary conductor. In the area between the rollers, the wire is guided through induction coils or primary windings in which alternating fields are generated. The heating of the wire also takes place here by means of the electrical resistance of the wire and by the current which flows in the short-circuit wire loop and is generated by induction. Devices of this type have the same disadvantages as described above for DE 2002373 A1.

It is therefore an object of the invention to provide a method and apparatus which allow in the heating of elongate metal products, preferably wires and tapes, throughput speeds, which in the range of working speeds of the upstream and downstream facilities, such as a high-speed winder machine, and at the same time the heating or heat treatment of products with very small cross-sections, eg of fine wires down to 0.005 mm in diameter. In this case, the fastest possible and over the cross section uniform heating should be achieved. Another object is to reduce the power consumption when using the principle of resistance heating and to keep the overall length of the heating device low. At the same time, it is an object of the invention to provide a method and apparatus which is suitable for heating elongated products within a drawing or rolling plant, i. Inline, can be arranged, e.g. before the last reduction stage, or before the last die in a wire drawing machine.

This object is achieved by a method and apparatus for heating elongated metal products having the features of the corresponding independent claims. Advantageous developments of the invention will become apparent after the features of the dependent claims.

In the inventive method for heating elongate metal products, preferably wires and strips, the thermal energy acts to heat a portion of the elongated product in a continuous process on the elongate product. The heating takes place in the areas of a heating section, wherein the thermal energy necessary for heating is generated by means of two different methods. This leads to the advantage that two methods which are known per se can be combined with one another and the advantages of each of the two methods can be utilized and the disadvantages avoided. It proves to be advantageous if with a first method, the thermal energy produced outside the product and transmitted through the jacket of the product on the continuous portion of the elongate product and a second method, the thermal energy in the continuous portion of the product itself is generated , In the first method, the thermal energy can be transmitted by heat radiation, heat conduction or convection. In the second method, the generation of the thermal energy by electrical resistance by means of direct feeding of electricity or generation of the current by induction is possible. The first method is used at the beginning of the heating phase and is used in this initial phase of heating simultaneously with the second method. In a second phase of heating, only the second process will affect the continuous part of the elongate product. The thermal energy generated by both methods acts on a portion of the elongate product over a period of time. This particular period of time corresponds to the time it takes a single point of the elongated product to go through the heating path.

According to the invention it is proposed that during the heating of the continuous portion of the elongate product by the heating distance, during a first portion of the heating distance, for the temperature change on the product per unit time positive values are selected and during a second portion of the heating distance, for the temperature changes values are selected on the product per unit of time, which range from positive to negative. By this heating method, the product is heated to a higher temperature in each period in a first section of the heating section. By appropriate control of the two different heat generation processes, a uniform heating over the cross section can be obtained at the end of this first section on the product. In the second section of the heating section, over which only the second heat generating process acts, the temperature of the product can now be controlled by appropriate control of this second method so that the temperature changes on the product increase per unit time, or are positive or decrease, or negative or the temperature remains constant. The continuous elongate product can thus be easily exposed to different heat treatment processes with variable temperature profiles.

An expedient embodiment of the subject invention provides that the elongated product is continuously drawn through the heating section, with a portion of the product is continuously in this heating distance and each point of a portion of the elongated product passes through this heating distance in a certain period of time and during a first portion of this period and over a first portion of the heating path, both thermal energy generating processes act simultaneously on the portion of the elongated product which is in that first portion and during a second subsequent portion of that period and over a second portion of Warming section only one of the heating process acts on the sub-area. The application of the two methods in this way leads to a compact construction of the heating section and also has the advantage that the product already heated by the first method does not have to be guided via a subsequent contact roller for the supply of the electric current and would thereby be cooled again. The two methods also ensure uniform heating of the product over the entire cross-section.

According to the invention it is proposed that in the first method, the thermal energy is generated in a heat radiator and transmitted by thermal radiation to a portion of the elongated product. Advantageously, the transmission of the thermal energy takes place on the jacket of the product without contact in the regions of the short-wave infrared. According to the invention, it may also be advantageous to apply the thermal energy via a bath with a carrier medium, e.g. to transfer a liquid, a gas or gas flames to the product. This type of heating of a portion of the continuous elongated product allows rapid heating, since there is a large difference between the temperature of the product and the temperature of the heat radiator at the beginning of the heating phase. The heating by means of this first method takes place only over a region in which the temperature difference is relatively large, i. over a limited distance.

The additional generation of thermal energy and heating of the portion of the continuous elongated product, which is located in the heating section, takes place in an advantageous manner by the second method in which the thermal energy either by introducing electric current into a portion of the product and is generated by the electrical resistance of the product or by the energy transferred by induction on the portion of the product and the thermal energy is generated in this portion of the product itself. In particular, in the generation of thermal energy by the electrical resistance of the product itself, there is now the advantage that because of the parallel heating by means of the first method, the temperature increases rapidly and therefore less power and thus less energy is needed. The heating to the desired temperature at the end of the first section of the heating section is much faster and over a shorter distance. When using an induction heater as a second method, the similar advantages arise analogously. Since both the first and second methods of heating use the heating methods in the range of their optimum effect, optimal lengths of the individual heating sections and the total heating section result. Since the heating to the desired temperature level takes place both in the initial region and in the end region of the heating zone, or in the field of application of the two processes, in a short time, the method according to the invention enables very high throughput speeds. These may be at 30 m / s and higher, which is why also products with small cross-sections within the continuous manufacturing process, i. Inline, can be thermally treated. In wire drawing devices therefore, when using the method according to the invention, the inline treatment and also the directly subsequent operation of a winder, in the case of fine wires with diameters down to 0.005 mm, become possible.

The apparatus according to the invention for heating continuous portions of an elongated metal product comprises transport means for the continuous transport of the elongated product through the device and means for generating thermal energy, wherein the continuous heating means comprises a first means for generating thermal energy Energy outside the product and for transmitting this thermal energy to the product and in parallel a second device comprising a directly acting on the wire electric resistance heater for generating thermal energy in the product itself, wherein the electrical resistance heating over the entire heating distance, which a first Partial section and a second section includes, and the first means for externally generating and transmitting thermal energy only over the first portion of the heating distance is arranged. This arrangement allows an optimal adaptation of the two different heating distances to the thermal needs and the spatial conditions for the arrangement of the device. An arrangement in which the beginning of the first subsection coincides with the beginning of the entire heating route leads to a compact construction of the heating route and also has the advantage that the product already heated by the first subsection of the heating route by the first method is powered by direct current does not have to be guided over a subsequent contact roller for the supply of electric current and it would be cooled down again. If the first subsection of the heating route only partially coincides with the entire heating route, the final temperature of the product at the end of the first subsection can be determined so that the electrical resistance in the second subsection is sufficiently high to reduce the power requirement in the desired manner. In addition, it is also possible to obtain different temperature profiles in the product in the second subsection of the heating section. The temperature can be further increased, kept constant or decreased by adjusting the current flowing in the product.

If this device for generating thermal energy, for example, installed in a fine wire drawing machine with multiple dies and, seen in the direction of the wire, arranged in front of the last die, there are significant advantages. A first electrical contact element to the wire, which belongs to a second device with direct electrical resistance heating, is arranged in front of the first section of the heating path with the device for externally generating and transmitting thermal energy to the wire. A second electrical contact element of the second device is arranged after the last die. Since the inventive heating device allows passage speeds which are the same as the speeds when drawing fine wire on the last die, a so-called hot drawing can be performed on the last die. In this case, the wire is annealed and heated before the last die, whereby the last die is less burdened and achieved a much longer life. The lifetime is increased by at least a factor of two. This leads to fewer interruptions to the replacement of the last die and thus increases the efficiency of the drawing machine. Advantageously, a cooling device is arranged between the last die and the second electrical contact element. This prevents that the largest heating of the wire occurs only after the die and thereby the tensile strength of the wire is reduced.

An advantageous embodiment of the subject invention provides that the first means for the external generation and transmission of thermal energy is a heat radiator, which radiates thermal energy in the regions of short-wave infrared. However, it may also be advantageous to use a heating bath with a heat transfer medium or an oven with at least one gas flame as the first device for the external generation and transfer of thermal energy. Such devices are known per se, but allow in connection with the present invention rapid heating of the continuous portions of the elongate product in a first section of the heating section. This then leads to the desired reduction of power consumption in the second device. According to a particular embodiment of the subject invention, the first means for externally generating and transmitting thermal energy from at least two sub-devices, wherein each of the sub-devices for heating the elongated product over a certain temperature level is determined. This embodiment enables an optimal adaptation of the first device to the desired temperature increase in the heating region.

According to the invention it is further proposed that the electrical resistance heating of the second device comprises two spaced-apart and related to the product electrical contact elements, for direct input and output of current in the continuous section of the product, and a power supply. A development of the invention provides that a first electrical contact element of the resistance heating, seen in the running direction of the wire, is arranged in front of the first device for the external generation and transmission of thermal energy and the second electrical contact element from the end of the first device by the length of the second Part of the heating section is spaced. By suitable, known per se control devices, the current flowing through the continuous section of the product can be controlled and thereby the thermal energy and thus the final temperature of the continuous section are controlled.

A further advantageous embodiment of the invention provides that the electrical resistance heating comprises an electrical induction device with an electrical primary power supply and the continuous portion of the product forms a secondary line of this induction device. According to the invention it is further proposed that the continuous portion of the product, which forms the secondary line forms a short-circuit loop and this short-circuit loop is guided over at least two rollers, wherein one of the rollers is designed as a short-circuit role. The technology known per se of the induction device is based on the principle of electrical transformers. The continuous portion of the product, e.g. a fine wire, which is guided as a short-circuit wire loop over two rollers, thereby forming the secondary conductor of this device. In known manner, a portion of this short-circuit wire loop by induction coils or primary windings, in which alternating fields are generated out.

The application of the inventive method is particularly advantageous in the thermal treatment of elongated metal products, preferably wires and tapes, wherein the wires or tapes are continuously conveyed through the device. Particularly useful is the application of the method in the manufacture of wires with final diameters of about 0.01 mm to about 8 mm, in particular for annealing these wires. The wires can have a round, square or profiled cross section. In the production of tapes, the use of the method is also particularly useful for small cross-sections. Especially with these small cross-sections of wires and tapes, the high throughput speeds achievable by the solutions according to the invention are of great interest. A further advantageous application is that the method is used to anneal wires in wire drawing equipment or to anneal tapes in belt rolling equipment. However, the method can also be used in the curing of wires and tapes or in other thermal treatments of elongated products of this type.

Also particularly advantageous is the use of the inventive device in the manufacture of wires and tapes in drawing and rolling equipment. It allows high throughput speeds of the elongated products, or wires and strips, and the heat treatment can be carried out without interrupting the processing operation, i. Inline within the drawing or rolling equipment or after the last cross-section reduction stage before the winding device done. Even with thicker wires, a uniform temperature distribution over the cross section is achieved during heating and no overheating of the outer jacket is necessary.

For example, when pulling wires, the following applications can be covered. It can wires are processed from all materials, which are electrically conductive. The temperatures reached by the heating can range from a few degrees Celsius to about 1000 degrees Celsius, for example for platinum. As is known, however, the maximum temperature must be lower than the critical temperature at which the strength of the wire could no longer withstand the pull-out forces. All wire diameters from coarse wire down to fine wire with a diameter of 0.005 millimeters can be worked down.

In the following the invention will be explained in more detail by means of embodiments with reference to the accompanying drawings. Show it: <Tb> FIG. 1 <sep> an apparatus according to the invention for heating wire with a direct feed of current for the electrical resistance heating, <Tb> FIG. 2 <sep> an inventive device for heating wire with an induction device for generating electricity for the electrical resistance heating, <Tb> FIG. 3 <sep> is a schematic diagram of the course of the heating in a device according to FIGS. 1 and <Tb> FIG. 4 <sep> the same device as FIG. 1, with an additional protective gas space around the wire.

Fig. 1 shows a device according to the invention in a schematic representation. A continuous heating device 3 in this case comprises a heating section 4 which has a first partial section 5 and a second partial section 6. By means of the heating device 3, an elongate product 1, in this case a metal wire, is drawn in the direction of the arrows 14 at a predetermined speed and thermally treated in the heating device 3. For conveying the wire 1 through the device transport means, driven in the example shown conveyor rollers 15 are present, as they are generally known in such systems. In the example described, the heating of the wire 1 is carried out for soft annealing, whereby the solidification, which has experienced the wire 1, for example in the preceding, not shown drawing or cross-sectional reductions, is eliminated. Depending on the material of the metal wire 1 to differently high annealing temperatures are necessary, for example, for copper 550-600 ° C, for steel 700-800 ° C or for platinum to 1000 ° C. In this case, the wire 1 at the beginning of the heat treatments, i. when entering the heater 3, ambient temperature, e.g. in the range of 10-50 ° C and the annealing temperature must be achieved until the exit from the heating device 3. The heating takes place only over a portion 2 with the length 16 of the elongated product, or wire 1. The length 16 of the portion 2 of the product 1 corresponds to the length of the heating section 4th

The continuous heating device 3 comprises a first means 8 for generating thermal energy outside the product 1 and a second means 7 having an electrical resistance heater acting directly on the product 1 for generating thermal energy in the product 1 itself. The second means 7 extends over the entire length of the heating section 4, which consists of a first section 5 and a second section 6. This second device 7 has two spaced-apart contact elements in the form of contact rollers 9 and 10. These two contact rollers 9 and 10 are arranged at a distance 17 from each other, which corresponds to the length of the heating section 4, said distance among other things determines the temperature increase in the product or wire 1 between these two contact rollers 9 and 10. The two contact rollers 9, 10 are connected to a power supply 11. For transmission and discharge of the current to and from the wire 1, the two contact rollers 9, 10 are looped around by the wire 1. Between the two rollers 9, 10 there is always a continuous portion 2 of the wire 1 and the current flowing between the two rollers 9, 10 through this portion 2 caused via the electrical resistance, the heating of this portion 2. The length 16 of this portion 2 corresponds in the example shown, the distance 17 between the two contact rollers 9, 10 and thus the length of the heating section. 4

Parallel to the second device 7, a first device 8 is arranged on the first section 5, directly after the initial region 18 of the heating section 4. In the example shown, this first device 8 consists of a heat radiator 22. Instead of only one piece, this heat radiator 22 can, if required, also be constructed of two or more subdevices 12, 13 if the heating is to take place stepwise. In this heat radiator 22, the thermal energy is generated outside of the elongated product or wire 1 and transmitted without contact by thermal radiation in the regions of short-wave infrared on the jacket of the wire 1. The heat radiator 22 may consist of one or more individual radiators, wherein a mirror surrounds the radiator or radiators so that the radiation is concentrated on the wire 1 in the center. Since the wire 1 at the beginning region 18 normally enters the first device 8 or the heat radiator 22 cold, and there is a high temperature difference between the heat radiator and the surface of the wire 1, a very rapid heating of the wire 1 takes place in the heat radiator 22 via the first section 5 of the heating section 4, the first device 8 consisting of the heat radiator 22 acts simultaneously with the second device 7 with the power supply to the wire increases via this section 5 as a result of rapid increase in temperature and the electrical resistance in the wire 1 quickly , As a result, the efficiency of the electrical resistance heating can be substantially improved and the effective length of the electrical resistance heating, i. the distance 17 between the two contact rollers 9, 10 are shortened. Then only the thermal energy which is generated in the continuous portion 2 of the wire 1 itself, i. E. the heating via this second section 6 is only dependent on the electrical resistance and the flowing current. In this case, the current flowing through the continuous partial region 2 of the wire 1 can be controlled so that the temperature of the wire 1 is kept constant over this second partial section 6 of the heating section 4, or continues to increase or decrease. For the change in temperature per unit of time on the elongated product or wire 1, it is thus possible to select values which lie in a range from positive to negative over the second subsection 6 of the heating section 4. The choice as to whether the values of the temperature change in the subsection 6 are in the negative or positive range can be dependent on the material of the wire 1. For materials which are susceptible to oxidation, for example copper, steel or silver, the temperatures at the end of section 6 should be below a value at which the material oxidizes upon contact with ambient air. This in particular when the wire 1 in the heating section 4 in a protective gas space 23 (as shown in Fig. 4dargestellt) is guided. If the temperature of the wire 1 at the end of the first subsection 5 is higher than the critical oxidation temperature, then a negative value for the temperature change is selected via the subsection 6. Thus, the temperature is lowered to a, in terms of the risk of oxidation, harmless value. For materials which are not sensitive to oxidation, e.g. Gold or tungsten, the value of the temperature change over the section 6 alone depending on the desired temperature treatment can be selected. With this arrangement according to the invention, different heat treatment methods can thus be produced and used, which makes possible the thermal treatment of elongated products 1 with different cross sections, up to very thin wires or bands and also of very different materials.

At the end of the heating section 4, a cooling device 19 is arranged in a conventional manner and the elongate product or the wire 1 is then fed in the direction of arrow 14 to a winder 20 and wound onto a coil 21. The device according to the invention enables heat treatments with high throughput speeds of the wire 1 and can therefore be used in direct connection with high-performance winders. As a result, the intermediate storage of the wire 1 can be avoided on auxiliary coils and the economy of such heat treatment equipment can be improved. The arrangement of the first device 8 and the second device 7 according to this example, for example, also enables the continuous heating device 3 in the same continuous process, even in wire drawing devices, i. Inline with the upstream wire drawing device and a downstream winder to wind the wire 1 to operate. This also applies to fine wires with diameters down to 0.005 millimeters down.

In an exemplary arrangement for the heat treatment of wires made of copper or stainless steel, with a diameter range of 0.025-0.035 mm, the first device 8, and the heat radiator 22 has an effective length of about 600 mm. The following second section 6 of the heating section 4 has a length of about 500 mm. The temperatures reached at the end of the first section 5 at the copper wire 500-600 ° C and the stainless steel wire 700-800 ° C. For copper wire 6 temperatures are aimed at the end of the second section, which are less than 300 ° C. In this example falls in the second section 6, the temperature, because on the one hand the wire 1 gives off heat to the environment and on the other hand, the heating in the wire 1 is adjusted by the second method so that only a part of the heat flow is compensated to the environment.

Fig. 2 shows a second embodiment of an inventive device, also in a schematic representation. Parts which are already described in a similar form to Fig. 1 are identified in Fig. 2 with the same reference numerals. In this exemplary embodiment, the second device 7 for generating thermal energy comprises an induction device 26 with a power supply 27. The continuous section 2 of the elongated product 1 forms a short-circuit loop 28 in the region of the heating path 4, which forms a secondary line of the induction device 26. The induction device 26 consists in a known manner of induction coils, or primary windings, in which alternating fields are generated, by means of which in the short-circuiting loop 28 in the direction of the arrows 30, 31 flowing current is generated. The elongate product 1 is also a thin wire in this example. This wire 1, which is to be subjected to a heat treatment, is conveyed by the conveyor rollers 15 through the continuous heating device 3. To form the short-circuit loop 28, a short-circuit roller 29 and two deflection rollers 32 are arranged in the heating device 3. The wire 1, which enters the heating device 3, is guided in the direction of the arrow 33 around the short-circuit roller 29 and forms an ascending section 34 and a descending section 35 of the continuous section 2 of the wire 1 and thus the short-circuit loop 28. The descending section 35th is performed at the end again in the direction of arrow 36 to the short-circuit roller 29 and withdrawn in the direction of arrow 14 from the heating device 3. The entire heating section 4 is formed by the short-circuit loop 28 of the wire 1, which consists of the ascending section 34 and the descending section 35 and the section which runs over the deflection rollers 32.

After the induction device 26, the first device 8, which in turn consists of a heat radiator 22, is arranged in this embodiment. This heat radiator 22 extends over the first section 5 of the heating section 4. The heating section 4 corresponds in this embodiment, the total length of the short-circuit loop 28. The induction device 26, which is part of the second means 7 for generating thermal energy, in a conventional manner be arranged after the first device 8 and the heat radiator 22. In both arrangement variants of the induction device 26, the first device 8, or the heat radiator 22, is arranged in a region in which the heating of the wire 1 begins. At the incoming into the short-circuit loop 28 (in the direction of arrow 23) wire 1, the heating begins by the induction device 26 on and / or after the contact region of the wire 1 with the short-circuit roller 29. Also in this embodiment, the first means 8 and Radiant heater 22 the task of rapidly heating the continuous portion 2 of the wire 1 to a temperature at which a lower current for additional heating on the electrical resistance is necessary and the desired course of the heating curve over the entire heating section 4 can be achieved. Via the first section 5 of the heating section 4, the two devices 7, 8 act in parallel to generate thermal energy. The second section 6 of the heating section 4, as shown in Fig. 1, is formed in this embodiment by the portion of the rising portion 34 after the heat radiator 22, the current around the pulleys 32 section and the descending section 35. In this second section 6, only the second device 7 with the electrical resistance heating acts on the continuous section 2 of the wire 1. The current flows throughout the short-circuit loop 28 regardless of the feed position. If necessary, therefore, as shown in Figs. 1 and 4, a cooling device 19 is arranged to cool a too heated wire 1 again.

3 shows in a temperature / path diagram in a schematic representation of the possible course of heating curves in inventive devices, in particular according to FIG. 1. In the horizontal direction of the diagram, the heating distance 4 is applied, which at the axis 37 of the contact roller. 9 begins and ends at the axis 38 of the contact roller 10. In the vertical direction of the diagram, the temperature of the elongate product or wire 1 is shown. In the case of the axis 37, the wire 1 has a temperature 40 which corresponds to the ambient temperature, e.g. between 20-50 ° C corresponds. Both the first device 8 and the second device 7 for generating thermal energy act on the wire 1 via the first section 5 of the heating path 4. In this section, therefore, the wire 1 is heated rapidly and the temperature rises accordingly. Depending on the material undergoing the heat treatment and the desired heat treatment process, the temperature 41 at the end 39 of the first section 5 of the heating section 4 may be lower than or equal to or higher than the final temperatures 42, 43 or 44 at the end 38 of the heating section 4. The maximum temperatures 44 may in turn depend on the material to be treated and the heat treatment process chosen, e.g. for platinum be up to 1000 ° C high. However, the maximum temperature 44 must in any case be lower than the critical temperature which applies to the elongate product 1. In this case, the critical temperature is that temperature of the elongate product or wire 1 at which the strength of the product 1 would reach the region of the pull-out force which acts on the product 1 at the end 38 of the heating path 4. This would mean that the elongate product or the wire 1 would be torn off.

From the diagram according to FIG. 3 it can be seen that the method according to the invention and the corresponding devices make possible an optimal design of the course of the heat treatment process. During the first sub-section 5 of the heating section 4, a positive course of the temperature change can be selected or set in particular by the appropriate choice and design of the first device for generating thermal energy. During the second sub-section 6 of the heating section 4, by adjusting the current introduced by the second thermal energy generating device 7, the temperature change on the product 1 per unit time can be determined to reach values ranging from positive to negative. The curve between the two temperature points 41 and 44 corresponds to positive values and the temperature profile between the two temperature points 41 and 42 negative values. The temperature profile between the two temperature points 41 and 43 shows an application in which a heat treatment at the same temperature is to take place via the second section 6.

When using this inventive arrangement in a wire drawing high throughput speeds up to 30 m / s and more can be achieved and very fine wires are processed with diameters down to 0.005 mm down. At these high throughput speeds of the wire 1, it is possible to lead the emerging at the end of the continuous heating device 3 and thus from the wire drawing machine wire 1 directly to a so-called winder 20 and with this machine directly in the desired shapes on a coil 21st wind. This is very advantageous since the winder machines 20 are very expensive and in this mode only one winder 21 is needed. There are no additional winder machines for the intermediate storage of the wire 1 necessary. It is also known that in the production of fine wires with diameters between 0.005-0.3 mm the last die is exposed to very high wear and therefore must be replaced very often. With a wire diameter of 0.02 mm and a throughput speed of 30 m / s, the life of this last die is, for example, only about 2 h. When using a described inventive arrangement before the last die, the life of this last die can be significantly increased, for example to 6 h and more. This leads to significant cost savings, since replacement dies are very expensive and with longer life of the die the number of interruptions in the production process, for changing the die, is reduced.

Fig. 4 shows substantially the same device as in Fig. 1. In addition, however, this device has a protective gas space 23, or active gas space, which is arranged around the continuous wire 1 and normally extends over the entire heating section 4. If necessary, this protective gas space 23 extends into the cooling device 19, which is enlarged for this purpose. This arrangement is particularly applicable to wires 1 made of oxidation-sensitive materials, e.g. Copper, steel or silver. In such oxidation-sensitive materials, the surface temperature must be lowered until it leaves the inert gas chamber 23 to a value at which no oxidation takes place in contact with the ambient air. This can be done by means of temperature control, as described for FIG. In addition, in the region of the second subsection 6, the protective / active gas can serve as a coolant in an end region of the protective gas space 23 and cause an additional temperature reduction in the wire 1. The temperature profile is determined in a conventional manner according to the desired temperature treatment of the wire 1. There may also be an additional coolant, e.g. Water are used.

Claims (24)

A method of heating elongated products (1) of metal, preferably wires and tapes, wherein the thermal energy for heating the elongated product (1) in a continuous process in a heating section (4), during a certain period of time on a continuous portion (2) of the elongated product (1), characterized in that the thermal energy for heating the portion (2) of the elongate product (1) is produced by means of two different heat generation processes. 2. The method according to claim 1, characterized in that generated by a first method, the thermal energy outside of the elongate product (1) and transmitted through the jacket of the product on the continuous portion (2) of the elongated product (1) and this first method is applied at the beginning of the heating and is generated by a second method, the thermal energy in the continuous portion (2) of the elongated product (1) itself. 3. The method according to claim 1 or 2, characterized in that during the heating of the continuous portion (2) of the elongated product (1) by the heating section (4), during a first section (5) of the heating section (4) for the Temperature change on the product (l) per unit time positive values are selected and during a second portion (6) of the heating distance (4), are selected for the temperature changes to the product per unit time values which are in a range from positive to negative. 4. The method according to any one of claims 1 to 3, characterized in that the elongate product (1) is continuously pulled through the heating section (4), wherein continuously a portion (2) of the product is in this heating section (4) and thereby each point of the portion (2) of the elongated product (1) passes through this heating path (4) in a certain period of time and during a first portion of this period and over a first portion (5) of the heating path (4) both processes for generating thermal energy simultaneously acting on the portion (2) of the elongate product (1), which is located in this first portion (5) and during a second, subsequent portion of this period and a second portion (6) of the heating section (1) only one of Heating method acts on the portion (2). 5. The method according to any one of claims 1 to 4, characterized in that generated in a first method, the thermal energy in a heat radiator (8) and contactless by thermal radiation to a portion of the elongate product (1) is transmitted. 6. The method according to any one of claims 1 to 4, characterized in that in a first method, the thermal energy is generated in a bath with a heat transfer medium and transferred by heat conduction and / or convection to a portion of the elongated product (1). 7. The method according to any one of claims 1 to 4, characterized in that in a first method, the thermal energy is generated by means of a gas flame and transmitted over the jacket of the product to a portion of the elongated product (1). 8. The method according to any one of claims 1 to 4, characterized in that in a second method, the thermal energy is generated by the flow of electric current through a portion of the elongated product (1) and by the electrical resistance of the product (1). 9. The method according to claim 8, characterized in that in the second method, the electric current is removed from a power source and via two spaced-apart contact elements in the portion of the elongate product and is discharged. 10. The method according to claim 8, characterized in that in the second method, the electric current is generated by induction and flows through the portion of the elongated product and the thermal energy is generated by the electric current in this portion of the product itself. 11. The method according to claim 5, characterized in that the non-contact transmission of the thermal energy takes place in the regions of the short-wave infrared. 12. Apparatus for carrying out the method according to claim 1, for heating continuous portions (2) of an elongated product (1) made of metal, preferably wire (1) or strip, in a continuous heating device (3), with a heating section (4 ), with transport means for the continuous transport of the elongate product (1) through the device and a device for generating thermal energy, characterized in that the continuous heating device (3) comprises a first device (8) for generating thermal energy outside of the Produce (1) and for transmitting this thermal energy to the product (1) and in parallel a second device (7) with an directly on the product or wire (1) acting electrical resistance heating to generate thermal energy in the product (1) itself includes, wherein the electrical resistance heating over the entire heating distance (4), which a a first subsection (5) and a second subsection (6), extends, and the first device (8) for externally generating and transmitting thermal energy is arranged only over the first subsection (5) of the heating route (4). 13. The device according to claim 11, characterized in that the first means (8) for the external generation and transmission of thermal energy is a heat radiator (22) which radiates thermal energy in the regions of the short-wave infrared. 14. The device according to claim 11, characterized in that the first means (8) for the external generation and transfer of thermal energy is a heating bath with a heat transfer medium. 15. The device according to claim 11, characterized in that the first means (8) for the external generation and transmission of thermal energy is a gas furnace with at least one gas flame. 16. Device according to one of the claims 12 to 15, characterized in that the first means (8) for externally generating and transmitting thermal energy from at least two sub-devices (12, 13), wherein each of the sub-devices (12, 13) for the heating of the elongated product (1) over a certain temperature level is determined. 17. Device according to one of the claims 12 to 15, characterized in that the electrical resistance heating of the second device (7) has two spaced apart and with the product (1) in communication electrical contact elements (9, 10) for direct entry and exit of electricity at the continuous section (2) of the product (1) and a power supply (11). 18. The device according to claim 17, characterized in that a first electrical contact element (9) of the resistance heater (7), seen in the direction of the wire (1), in front of the first means (8) for the external generation and transmission of thermal energy is arranged and the second electrical contact element (10) is spaced from the end of the first device (8) by the length of the second section (6) of the heating path (4). 19. Device according to one of the claims 12 to 15, characterized in that the electrical resistance heating of the second device (7) comprises an electrical induction device (26) with an electrical primary power supply (27) and the continuous portion (2) of the product (1). forms a secondary line of this induction device. 20. Device according to claim 19, characterized in that the continuous portion (2) of the product (1), which forms the secondary line, forms a short-circuit loop (28) and this shorting loop (28) is guided over at least two rollers, wherein one of Rolls is designed as a short-circuit roller (29). 21. Application of the method according to one of the claims 1 to 11 in the thermal treatment of elongated products (1) made of metal, preferably wires and tapes, wherein the wires or tapes are continuously conveyed by a device which is operated by this method. 22. Application according to claim 21, characterized in that the method is used for annealing wires in Drahtzieheinrichtungen. 23. Application according to claim 21, characterized in that the method is used for annealing strips in devices for rolling strips. 24. Use of the device according to one of the claims 12 to 20 in the manufacture of wires and tapes in drawing or rolling devices.