DE2014592A1 - Method and device for heating large surfaces to a high temperature - Google Patents

Description

Dipl.-Ing.

QrWKAPT7 51 AACHEN, March 24, 1970

5L-MMtIZ. Augustastraßel4-16 Phone 503731

Patent attorney 2014592

LA SOÜDURE ELECiDRIQÜE AUiDOGENE, PROCEDES ARCOS, S.A. in Brussels (Belgium)

description

Method and device for heating large surfaces to a high temperature

The invention relates to a method and a device for Heating of large surfaces of workpieces or others Objects at high temperature.

For heating the surface of workpieces or others It is known to use a plasma flame as a heat source for high temperature sharing. The creation of the plasma flame is done by a plasma torch, which both with Direct current as well as alternating current can be operated. In the known plasma torches, an arc burns between two or more essentially coaxial electrodes. Further In the known plasma torches, this arc under pressure is used to generate a plasma. Gas supplied. This results in eich a plasma flame which is driven out of the plasma torch and which has a circular or substantially circular cross-section.

In all known plasma torches, the one generated by them Plaenaflanuie a relatively small cross-section and

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has a very significant energy density. Such plasma torches are therefore also particularly suitable for a limited surface of a workpiece or other To supply the object with a large amount of heat energy.

In many cases, however, it is desirable, and not just To heat a small area of the surface of a workpiece or other object, but rather to heat the entire surface of large workpieces or other objects to carry out at high temperature.

The invention is therefore based on the object of a method and a device for heating large surfaces of To create workpieces or other objects at high temperature using plasma heating.

To solve this problem, the invention provides a method which is primarily characterized in that for heating the surfaces of the workpieces or other objects at least one row of separated ones Plasma flames is used. For this purpose, it is further provided according to the invention that to generate each row from one another separate plasma flames a group of cathodes formed by anode-cathode pairs connected to a power source and anodes is used. The new method therefore also makes it possible to simultaneously use the plasma flames to cover a large area of the surfaces of the

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workpieces or other objects to be heated
treat.

In the new method, it can also be provided according to the invention that the current supplied to each cathode and anode pair is regulated individually. This makes it possible to
different heating of the surfaces by means of the plasma flames generated by the individual cathode-anode pairs
to effect the workpieces and other objects.

In the new method, the invention also provides that, when two groups of cathodes and anodes are present, the individual cathode-anode pairs are fed with direct current
and the anodes of both groups of cathodes and anodes
Alternating current is supplied. The direct current makes daoe-i
causes the arc to be maintained, while the alternating current heats the plasma flames generated and other effects can be exerted.

As far as the workpieces or other objects,
the surfaces of which are to be heated are moving parts, the invention also provides that these are moved with their surface below the plasma flames. Possibly
the implementation of the new procedure is particularly special

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The invention also provides for two Groups of cathodes and anodes and an alternating current supply to the anodes of these two groups gate that by parallel arrangement of the cathode-anode groups at a distance from each other the heating of the surface of the workpieces or the like partly by heat transfer and partly by resistance heating he follows. This exg.bt calibrates a particularly intensive heating of the surface of the workpieces or the like.

In addition, when two groups of cathodes and anodes are present, the invention also provides a further procedure, according to which by arranging the two at an angle Groups of cathodes and asodes respectively to the plasma flames generated by opposing cathode-anode pairs a single combined plasma flame. at This procedure results in combined plasma flames, which have a particularly high heating effect on the surface of the Workpieces or the like. Ability to exercise.

To carry out the new method, a device is also provided according to the invention, which is essentially characterized in that it has at least one cathode device with at least two solid electrodes Cathodes have at least one anode device with a number of anoias formed by nozzles corresponding to the number of cathodes of the cathode device, so that they generate a supply of plasma

Has gas to the nozzles and 4ass them a Stromansohluß

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for the cathode device and the anode device.

A preferred embodiment of the new device provides thereby yor ₉ that the anode means to form consists of a Mehrfaeh anode of a single piece and has the nozzles of this resulting openings. If necessary, the piece forming the multiple anode is preferably made of copper or silver.

In all embodiments of the new device, means for cooling the cathodes of the cathode device are expedient and anodes of the anode device provided by To avoid overheating of the same

Regarding the stroking of the cathode-anode pairs each According to the invention, the cathode and anode device of the new device can be provided so that a separate controllable direct current source is provided for each cathode-anode pair of each cathode and anode device. on the other hand can erfladungigemaß the power supply of the cathode-asode-Peare of the cathode and anode device of the new device but also take place in that a direct current source is provided for each cathode-anode device and the individual cathode-anode pairs of the cathode and anode device are each connected to this direct current source via a variable resistor.

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In one embodiment of the gate direction according to the invention the cathodes of the cathode device and the anodes of the anode device are arranged in a straight line. at this embodiment results in a linear arrangement of the for heating the surface of the workpieces or the like serving plasma flames.

Another embodiment of the device according to the invention "provides that it has two sets of cathode-anode devices. Optionally, those of these two Groups of cathode-anode devices generated plasma flames for heating the surface of the workpieces or like working together.

In the case of a device with two groups of cathode-anode devices, a further embodiment of the same provides that the anode devices of the two cathode-anode devices are connected to a Weohsel current source. This Weohselstromquelle then heats the plasma flames generated by the cathode-anode units causes. In addition, this Weohsel power source can also trigger other effects.

In the embodiment of the device in which two Groups of cathode-anode devices are present, it can also be provided that these are evenly spaced are arranged from each other and parallel to each other. Provided

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while the anodes of the two anode devices are connected to an alternating current source, there is heating the surface of the workpieces od. The like. Partly by heat transfer and partly by resistance heating, wherein the resistance heating comes about in that the alternating current from the plasma flames of one cathode-anode device through the workpiece to the plasma flames of the other Cathode-anode device flows.

On the other hand, in the embodiment of the device, which has two groups of cathode-anode devices, it can be provided that the two groups of cathode-anode devices are arranged at an equal distance from one another and mutually inclined to one another in such a way that the races they generate γοη plasma flames läsga meet in a straight line. If necessary, the plasma flames generated by opposing cathode-anode pairs then each combine to form a single combined plasma flame. If the anodes of the two anode devices are connected to an alternating current source in this configuration of the gate direction, an alternating current flows through the plasma flames of one cathode-anode device to the plasma flames of the other cathode-anode device and causes these plasma flames to heat up.

According to a different embodiment of the new gate direction the invention provides that the cathodes of

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Cathode device and the anodes of the anode device are arranged on a circular line. This embodiment of the gate direction is suitable for heating the surface of Workpieces or other objects of a special kind.

In an embodiment of the embodiment in question the gate direction is provided that the common axes of the cathodes and the associated anodes of all cathode-anode pairs are in a parallel position. The sound of the cathode-anode pairs in the direction of the gate is therefore also a wreath generated by plasma flames.

Another embodiment of the embodiment of the door direction in question provides, however, that the common Axes of each cathode and the associated anode of the individual cathode-anode pairs in a radial arrangement with respect to the center of the circle on which they are located. In this configuration of the gate direction then generate the cathode-anode pairs plasma flames, which starting from a circle are directed in a star shape to the center of this circle.

Further features and gate parts of the method and the gate direction according to the invention result from the following Description as well as the drawing.

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In the drawing are various exemplary embodiments of the Device according to the invention, for example and shown schematically, namely show:

1 shows an embodiment of the device in a vertical longitudinal section,

Pig. 2 the device according to Pig. 1 in horizontal Longitudinal section along line II-II of the Pig. 1,

Pig. 3 the Pig. Lund 2 corresponding devices up to 6 with other means for their power supply,

Pig. 7 shows a further embodiment of the device with two groups of cathode and anode devices arranged inclined to one another as well as a workpiece located below it in a perspective view,

Pig. 8 the same device and the same

Workpiece in cross section along line VIII-VIII of the Pig. 7,

Pig. 9 shows another embodiment of the device with two groups of parallel to each other arranged cathode-anode devices as well as one located below the same Workpiece in a diagrammatic view,

10 shows a different embodiment of the device in a diagrammatic view,

11 shows the device according to FIG. 10 in cross section and

FIG. 12 shows yet another embodiment of the preamble. direction in cross section.

In the figures of the drawing showing the various forms of the device, the same ropes are shown given the same reference number

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You in Fig. 1 schematize * !, the device shown in section has an elongated device 1, preferably made of copper, and is in a row with a series arranged openings or nozzles 2 provided. Corresponding individual electrodes 3, which preferably consist of tungsten, and a cooling system are arranged in the axis of these nozzles 2 known ixt have. The electrodes 3 are connected to a non-conductive common plate 5 and extend through chambers 6 which are each in communication with the nozzles 2. The chambers 6 are provided with channels 7 »which are provided in the partition walls of these chambers, plasma-generating (ras fed. These channels 7 preferably work together with an individual control device (not shown). she Electrodes 3 are electrically insulated from device 1 by means of insulating plates 8. You facility 1 stands with one of the two terminals of a direct current source 4 by means of a conductor 9 in connection and thus, if it is is the positive terminal of the power source 4, a Mehrfaoh anode. The Hehrfaoh anode formed by the device 1 is otherwise with an inlet pipe socket 11 and an outlet pipe stub 12 is provided for cooling water, which circulates between the two 2 (cf. Pig. 2).

You electrodes 3 are in turn connected in parallel to one Soldered conductor 10, which is connected to the other terminal of the direct current source 4. The output of the electrodes 3 is in such a way, e * i the Ib current flowing in each individual circuit

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can be regulated separately. The electrodes 3 are thus represents the series of cathodes corresponding to the multiple anode. Under the effect of the flow of electric current and the Pressure of the plasma-generating gas conducted into the chambers 6, arcs burn between all cathodes and anodes, and hot grasses in the form of plasma flames 13 are expelled through the nozzles 2.

Power sources can be used to regulate the current of each arc use of various kinds. A separate Direct current source 14 for each cathode 3 (see. Pig. 3) can be used, which on the one hand with this cathode and on the other hand is connected to a bus bar 9 leading to the multiple anode 1. You can also use a single Use current source 15, then separate variable resistors 16 between this current source 15 and each of the cathodes 3 are arranged (see. Fig. 4).

In contrast, in another embodiment of the Device according to the invention all cathodes 3 with the The same voltage is fed, while the nozzles 2 of the multiple anode 1 are either connected to a separate power source 14 are connected (cf. FIG. 5) or are connected to a single current source 15 with the interposition of individual control resistors 16 (cf. FIG. 6). To this end the nozzles 2 of the multifunctional anode are mutually electrical through elements 17 which surround them and consist of insulating material isolated.

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You ignition of the arcs can be achieved by that the individual cathodes 3 briefly with the associated Brings anodes into contact and then removed from them again. Gate ways are used to ignite the arcs but a high frequency spark. If the high-frequency generator used has sufficient power, several arcs can be ignited at the same time. However, a high-frequency generator is preferably used for this purpose low power is used, i.e. one that causes little radio interference. This generator will turn after connected to each cathode 3 and the Hehrfaoh anode 1, in such a way that the various arcs in one be ignited in a specific order.

The current and the amount of gas can be regulated at each nozzle 2 in order to control the power transmitted in the arc, to change the gas temperature and the gas composition.

The multiple anode 1 can be one of copper or silver existing cooled bar, which for example at intervals of 10 mm with holes of 2 to 8 mm Durohmesser is provided. The power of each arc can be, for example, 10 to 20 kW. Possibly There are 100 nozzles in total on a bar length of 1 m and an output of 1000 to 2000 kW will be in the form a series of parallel plasma flames that form a very high temperature plasma curtain.

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Such devices are versatile. They are particularly suitable for carrying out heat treatments with high temperature, such as refractory spraying, nitriding hardening, annealing and the Surface hardening of parts with a large width, which are moved under the plasma curtain.

By arranging several plasma flame series of this type in parallel, one can create plasma flame fields which it

ρ
allow enormous power in the order of 50,000 to 100,000 kW to be transmitted per m. Such plasma flame fields can be used as a source for the emission of light in light ovens or as a high-power radiator.

The Pig. 7 and 8 show a workpiece 33 which is treated by a device according to the invention. This device has on the one hand two combined multiple anodes 18 and 19 which are each connected to the secondary terminals 20 and 21 of a transformer 22 by means of conductors 23, 24. On the other hand, this device has two series of cathodes 25 and 26, respectively. The cathodes 25 are each connected to a terminal of a separate direct current source, the other terminal of which is connected to the multiple anode 18 by means of a bus conductor 29. In a corresponding manner, each of the cathodes 26 is connected to a terminal of a separate power supply source 28, the other terminal of which is connected to the multifunctional anode 19 by a busbar 30.

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The cathodes 25 and the Mehrfaoh anode 18 on the one hand and the Cathodes 26 and the multiple anode 19, on the other hand, are arranged inclined to one another in such a way that the plasma flames 13, which emerge from the Hehrfaoh anodes 18 and 19, with their edges combined to form a single series of Hitting plasma flames 31. If the plasma flames 31 in are sufficiently close to each other, the series of plasma flames is uninterrupted and forms a kind of plasma knife.

If necessary, in the device according to fig. 7th and 8 of the zone in which the plasma flames 13 meet, powder is fed through a series of outlet nozzles of a sprayer 32 located in the one between the two Cathode-anode groups existing angular space is located. In Pig. 7, this funnel 32 is only indicated by dashed lines Lines shown so as not to cover the lower part of the device. In contrast, FIG. 8 shows the funnel 32 in full lines.

According to the type of treatment to be carried out, in the device according to FIGS. 7 and 8, the workpiece 33 according to FIG the arrow X drawn in FIG. 7 can be displaced.

According to another embodiment of the invention, in which one wttnsoht, for example, a short-term supply of energy and a very significant shift in the energy application point to get the different arcs in certain

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Time intervals that are "for example one or more hundredths of a second apart, and ignited in a certain order. Of course you can, also the different ones Extinguish arcs in a corresponding manner in a specific order and according to a specific program. as Application example for this embodiment of the invention is the production of several successive weld points to call. When the device according to the invention is used for spraying, the material to be sprayed becomes preferred fed through one or two channels to each nozzle. In doing so, it may be desirable to reduce the amount of spray to be sprayed Material, which can be formed, for example, from a powder, to regulate at each nozzle. Such devices make it possible to obtain two or more plasma flames located fairly close together. Of course you can combine these devices with the device described in Belgian patent 623 218 and in which an alternating current to the direct current maintaining the arc is superimposed.

As a further embodiment of the device according to the invention be the heating of a metal strip 34 moving under it, partly by plasma flames and partly by Resistance heat mentioned what is shown in FIG.

In this embodiment, two devices 35 and 36 with cathodes and multiple anodes evenly spaced arranged from each other. Each of these two bodies 35,

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has on the one hand a multiple anode 18 and 19 and on the other hand a series of cathodes 25 and 26. The cathodes 25 and 26 are each in electrical connection with one terminal of individual direct current sources 27 and 28, the other Terminals have a collective connection to the associated multiple anode 18 and 19, respectively. In addition, the two multiple anodes 18 and 19 are each connected to the secondary winding 37 of one AC transformer 22 connected to large power. In this device, the alternating current flows from the transformer 22 through each plasma flame 13 emerging from the individual nozzles of one of the multiple anodes, then through the warming metal band 34 »which is located in the direction of arrow 7 shifts, and finally through the plasma flames emerging from the nozzles of the other multiple anode to the Transformer 22 back.

This device permits the heating of the moving metal strip 34 on the one hand by means of the plasma flames 13 duroh direct heat transfer to this and on the other hand duroh resistance heating due to the alternating current flow through the Metal band 34 utilizing the Joulesohen effect. This mode of operation also enables an intensive flow of current in a workpiece to be heated without a mechanical one There is contact between a power supply terminal and this workpiece. Duroh this mode of action are therefore also the with the resistance heating of workpieces to high temperatures existing problems »or simplified · The mode of operation is particularly suitable for sintering calibration moving »

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metal strips produced by cold rolling metal powders. Since in this embodiment the superimposed alternating current preferably flows along the path that forms the least resistance, there is also the possibility in advance determine and regulate the current distribution by measuring the direct current power and the amount of gas escaping from each anode or nozzle varies and thus regulates the electrical resistance of each plasma flame through which the alternating current flows.

In another embodiment of the invention, which for Spraying very large amounts of material onto sheets or strips is intended, two multiple anodes are used, which Generate plasma flames that meet a few millimeters from the Mehrfaoh anodes. Between the two multiple anodes A Weohselstrom voltage is applied in such a way that it causes intensive heating of the plasma flames as a result of the Durohfließens an alternating current caused by this. The material to be sprayed is either in each nozzle, between the two Multiple anodes or both in each nozzle and between the two multiple anodes at the same time.

In the embodiments of the device according to the invention, all nozzles are usually arranged parallel to one another and have the same dimensions. Uu appropriate To achieve heat effects, however, one can also arrange the various nozzles with different orientations and they have a different cross-section.

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So, as shown in fig. 10 and 11 use an annular multiple anode, the nozzles of which are parallel to each other as well as at equal distances from each other are arranged concentrically on a circle.

The device shown in FIGS. 10 and 11 beeitzt three concentric rings 38, 39 and 40 interlocking with each other are connected. On the upper ring 33, which is made of highly conductive Consists of metal, a series of eight cathodes 41 are arranged concentrically and evenly spaced from one another. The upper Ring 33 is also provided in its interior with channels 42 and 43 for the flow of cooling water. The lower ring 40 is formed by a series of eight nozzles 44, which correspond to the eight cathodes 41. The nozzles 44 are of one common cooling chamber 45 surrounded for the flow of cooling water.

A third ring 39 made of insulating material, such as asbestos bakelite, is arranged between the two rings 38 and 40. This ring 39 is provided with eight holes which are equally spaced from one another and which are arranged in such a way that they allow the eight cathodes 41 to pass through. To the side of the holes in the ring 39, channels 46 are provided, which serve to introduce the gas generating the plasma into the chambers which surround the cathodes 41. Such a device can be used for uniform heating of a mass tine very high! Temperature as this is necessary for pulling single crystals, whereby

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then pulling the single crystals along the axis of the ring-shaped Multiple anode takes place.

According to another in Pig. The embodiment of the invention shown schematically in FIG. 12 is an annular multifunctional anode 62 used, in which the axes of the nozzles and of the corresponding cathodes 64 are in a radial position. Such Devices are designed for heating moving Rods and rods can be used, for example around them to clean their scope by melting them in zones. The one in Pig. 12 illustrated embodiment moves a Rod 65 within the convergence zone of the plasma flames 13

As already stated, you can with the invention Gate direction the resulting heat effect by changing the Diisenf oma, the gas leakage and the power of the change individual arcs. You can also use this Change the direction of the gate but also the distance between the nozzles by one to get more or less high energy density. In addition, there is, for example, the use of rectilinear multiple anodes, the possibility of transmitting more energy in the center or at the ends of these multiple anodes.

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Claims (18)

20H592 claims 1. A method for heating large surfaces to a high! Temperature, characterized in that »for heating the Surfaces at least one row of separated plasma flames is used. . 2. The method according to claim 1, characterized in that for To generate each row of separate plasma flames, a group of cathodes and anodes is used, which is formed by cathode-anode pairs connected to a power source. 3. The method according to claims 1 and 2, characterized in that each cathode-anode pair is supplied Electricity is regulated individually. 4. The method according to any one of claims 2 and 3, characterized in that in the presence of two groups of Cathodes and anodes the individual cathode-anode pairs are fed with direct current and the anodes of both groups Alternating current is supplied. 5. The method according to any one of spoke 1 to 4, characterized in that the workpieces with their surface below the plaema flames are moved. 0 0 9 8 Λ 1/1291 6. Yerfahren according to claim 4 and 5, characterized in that by parallel arrangement of the cathode-anode groups In Distance from each other the heating of the workpiece surface takes place partly through heat transfer and partly through resistance heating. 7. Yerfahren according to any one of claims 2 to 5 »characterized in that in the presence of two groups of Cathodes and anodes by inclined arrangement of the same generated by opposing cathode-anode pairs Plasma flames are each combined into a single combined plasma flame. 8. Device for performing the method according to one of the Claims 1 to 7, characterized in that it has at least one cathode device with at least two cathodes (3, 25, 26, 41, 64) formed by solid electrodes, that with you at least one anode device with one of the Number of cathodes corresponding to the cathode device Number of anodes formed by nozzles (2, 18, 19, 44, 62) is provided that they have a supply (7) of a plasma generating Gaees to the nozzles and that they have a StromansohluB | 9> 10} 29, 30) for the cathode alignment as well as the Aaodeneinriohtung has. 9. Yorriohtung naoh claim 8, characterized in that the Anode installation Forming a multiple anode (1, 18, 009841/129 1 20H592 19 »40, 62) consists of a single StUoIc and this the Has nozzles resulting openings. 10. Device according to claims 8 and 9, characterized in that for each cathode-anode pair (3, 2; 25, 18; 26, 19; 41, 44; 64, 62) each cathode and anode device has a separate controllable direct current source (14, 27, 28) Is seen 11. Device according to claims 8 and 9, characterized in that one for each cathode and anode device Direct current source (15) is provided and the individual cathode-anode pairs (2, 3) of the cathode and anode device via a variable resistor (16) each to this DC power source are connected. 12. Device according to one of claims 8 to 11, characterized in that the cathodes (3, 25, 26) of the cathode device and the anodes (2, 18, 19) of the Anodenelnriohtung are arranged in a straight line. 13. The device according to Anspruoh 12, characterized in that they have two groups of cathode-anode devices (25, 18; 26, 19). 009841/1291 14. Door direction according to claim 13 »characterized in that the anode devices (18, 19) of the two cathode-anode devices (25, 18; 26, 19) to an AC power source (22) are connected. 15. Gate direction according to one of claims 13 and 14 »thereby characterized in that the two groups of cathode-anode devices (25, 18; 26, 19) are equally spaced are arranged from each other and parallel to each other. 16. Gate direction according to one of claims 13 and 14 »characterized in that the two groups of cathode-anode devices (25, 18; 26, 19) at an equal distance from one another and mutually so inclined to one another are arranged so that the rows of plasma flames (13) generated by them meet along a straight line. 17. Gate direction according to one of claims 8 to 11, "thereby characterized in that the cathodes (41 »64) of the cathode device and the anodes (44, 62) of the anode device are arranged on a circular line. 18. Gate direction according to claim 17 »characterized» that the common axes of the cathodes (41) and the associated anodes (44) of all cathode-anode pairs are in a parallel position. OQ98A 1/129 1 20H592 19 «Device close to claim. 17, characterized in that the common axes; each cathode (64) and the associated anode (62) of the individual cathode-anode pairs in a radial arrangement with respect to the center of the Circle on which they are arranged. 00984 1/129