This application is a national stage of PCT/DE2003/003088 filed Sep. 17, 2003 and based upon DE 102 43 739.4 filed Sep. 20, 2002 under the International Convention.
1. Field of the Invention
The invention relates to a plasma wire burner for plasma spray having at least two burner tubes for supplying electrodes which are in the form of wires and are passed through the burner tube in the direction of the surface of an object to be coated via a feed device which has numerous guiding and/or sliding elements which are mounted such that they can rotate.
2. Related Art of the Invention
Plasma wire burners having a variant large number of guiding means for the spray wire are already known in a general form. JP 01 198 461 A, JP 02 245 255 A, JP 02 307 555 A, JP 05 168 985 A and JP 07 090 537 A should be cited by way of example.
An inner burner for plasma wire spraying of cavities, in particular of cylindrical running surfaces, is already known (DE 198 41 617 A1). The inner burner has two burner tubes which are provided for feeding wire electrodes. The electrodes are melted by means of a plasma. Furthermore, the inner burner has a gas supply for a process gas, which is provided for transportation and atomization of the molten wire material in the direction of that surface of the cavity which is to be coated. The electrodes or the wires are fed towards one another through the burner tubes on the outlet side and in the area of the plasma, with the plasma from the electrode wires, which is arranged in the contact area of the wires, being arranged in the area of the gas flow of the emerging process gas. The gas flow of the emerging process gas, which is referred to for simplicity in the following text as the main gas flow direction, is arranged transversely with respect to the main transportation direction of the wires, which is governed by the burner tubes. Layers which are sprayed by means of an inner burner such as this onto, in particular, a metallic substrate, preferably a cylindrical running surface, are generally highly porous.
A welding burner with a feed apparatus for electrodes in the form of wire is known from JP-11 342471, which electrodes are passed through the burner tube via rollers which are mounted such that they can rotate, in the direction of that surface of an object which is to be coated, with the feed device being provided outside the welding burner.
The invention is based on the object of improving the wire feed in the plasma wire burner in such a way that the wire is guided precisely to the short-circuiting point on the plasma wire burner.
According to the invention, the object is achieved in that the feed device which has guiding and/or sliding elements and by means of which the wire is deformed in the elastic or plastic range is integrated in the burner tube or is held in it, and in that the sliding elements are in the form of rollers or rollers having ball bearings.
It is advantageous for the burner or the supply tube to be formed from three components which can be joined together, and for the feed device together with its sliding elements to be integrated in the burner in the area of at least one intersection plane of two parts which can be joined together.
It is also advantageous for the burner or the supply tube to have an approximately circular cross section when viewed from the front, and for the central section of the burner or of the supply tube to be approximately wedge-shaped when viewed from the front.
It is also advantageous for two feed apparatuses to be provided and for one feed apparatus in each case to be arranged in the area of in each case one intersection point of the burner and of the supply tube, with a cathode wire being guided via the first feed apparatus, and an anode wire being guided via the other feed apparatus. Channels which are not illustrated in the drawing are provided for this purpose in the burner tube, via which it is also possible to pass the inert gas, by means of which the wires and the rollers can also be cooled.
This results in the advantageous design and arrangement of the deflection device in conjunction with the sliding elements ensuring that the wire is guided exactly within the plasma wire burner as far as the short-circuiting point of the burner, for which purpose the wire can also be deformed in the elastic range without any significant increase occurring in the friction forces, and thus without any significant increase in wear. The wire is guided precisely by the change in direction in the contact-making wire guides.
For this purpose, it is advantageous for the deflection device to have numerous deflection rollers which are arranged one behind the other at a distance from one another and interact with at least one deflection roller whose diameter is the same or larger, which, together with the numerous deflection rollers for holding the wire, form a guide path.
According to one development, an additional option is for the larger deflection roller to be arranged with its external circumference at a distance from the numerous opposite deflection rollers which are arranged one behind the other, with the distance between the larger deflection roller and the numerous deflection rollers which are arranged one behind the other and interact with it being approximately of the same size as or larger than the diameter of the wire.
It is also advantageous for each deflection roller to be arranged at the same distance from the external circumference of the opposite large deflection roller.
For this purpose, it is also advantageous for the wire to be guided via a deflection device which has numerous guiding and/or sliding elements which are mounted such that they can rotate, by means of which deflection device the wire is deformed in the elastic or plastic range, with the deflection device having numerous deflection rollers which are arranged one behind the other and are mounted in ball bearings, and having at least one deflection roller which has a larger diameter, is likewise mounted in a ball bearing and is arranged with its external circumference at a distance from the numerous deflection rollers which are arranged one behind the other, with the distance being approximately the same as or larger than the diameter of the wire. Since the individual sliding elements, which are arranged one behind the other, or the deflection rollers, which are arranged on axes by means of ball bearings, are positioned between two parallel-running discs this results in very exact, low-wear wire feeding in a very small space and in optimum feed control of the wire as far as the short-circuiting point of the plasma wire burner.
For this purpose, the individual ball bearings may be in the form of miniature ball bearings, so that it is possible to considerably reduce the overall volume of the entire apparatus. Furthermore, the use of the rollers which are held in ball bearings considerably reduces the maintenance intervals for the plasma wire burner. A further advantage of the use of the deflection rollers is also that the feed-proof force can be reduced and the wear can be kept very low.
Finally, one preferred embodiment of the solution according to the invention provides for the deflection rollers to have a guide groove, which is arranged concentrically with respect to the axis, for guiding the wire.
It is of particular importance for the present invention that the shafts of the deflection rollers are held in two plates which are arranged at a distance from one another, and between which the deflection rollers are arranged such that they can rotate.
It is also advantageous for a sliding contact to be provided in front of and behind the deflection rollers and to be pressed against the surface of the wire by means of a spring.
The use of a sliding contact in front and behind the ball bearing deflection optimally maintains the power supply to the wire.
It is also advantageous for numerous deflection rollers which are arranged one behind the other to be provided in a first row and in a second row at a distance from it, in order to guide the wire.
Furthermore, it is advantageous for at least three sliding elements to be provided, two of which are arranged one behind the other.
It is also particularly advantageous for a total of only three deflection rollers or sliding elements to be provided. In this case, it is advantageous for two sliding elements to be provided on one side of the electrode and for a further deflection element to be provided on the other side of the electrode, to be precise between the two deflection rollers, so that this results in a three-point contact for the electrode.
Further advantages and details of the invention are explained in the patent claims and in the description, and are illustrated in the figures, in which:
In the drawing, 1 denotes a supply tube for a plasma wire burner which can be used in particular for plasma wire spraying of cavities, for example of cylindrical running surfaces. The inner burner for this purpose has a nozzle head 2 which is connected to burner tubes 3. Two burner tubes 3 for feeding electrodes 5, which are in the form of wires, are located at the outlet opening of the nozzle head 2. The electrodes or the wires 5 are intended to be melted in a plasma. The droplets which are formed from the molten wires 5 are transported and atomized by a process gas in the direction of that surface of the cavity which is to be coated.
In order that the plasma can be formed between the ends of the wires 5, the two wires 5 are fed towards one another on the outlet side after the burner tubes. The wires are fed by means of a feed device or deflection device 7, which is illustrated schematically in the two exemplary embodiments shown in
The feed or deflection device 7 comprises two plates 12 and 13 which are arranged at a distance 4 from one another, run parallel, and can be held together via connecting elements which are not illustrated in the drawing.
The plates 12 and 13 of the deflection device 7 have numerous guiding or sliding elements 8 which are arranged one behind the other and are held by means of shafts 10 in the plates 12 and 13 such that they can rotate. The individual deflection rollers 8 are mounted on the shafts 10 such that they can rotate freely by means of ball bearings which are not illustrated in the drawing.
As can be seen in
As can be seen from
At the same time, the advantageous arrangement of the deflection rollers 8 and 9 and their design increase the maintenance intervals for the plasma wire burner.
The individual deflection rollers 8 and 9 as shown in
As can be seen from
The individual deflection rollers 8 are arranged with their external circumference at the same distance 4 from the external circumference of the larger deflection rollers 9. The deflection device 7 can also be equipped with a sliding contact 15, as shown in
The sliding contact 15 may also comprise a piston which is guided in a cylinder 17 and at whose end the deflection roller or the sliding element 8 is arranged, which is pressed against the surface of the wire 5 by means of the spring 16. The sliding contacts 15 ensure adequate power transmission and the electrical power supply to the wire 5.
According to a further example, which is illustrated in
The burner or the supply tube 1 may have an approximately circular cross section when viewed from the front (
The described burner 1 has two feed apparatuses 7 in the area of the intersection points 20 of the burner or of the supply tube 1, with a cathode wire being guided via the first feed apparatus 7, and an anode wire being guided via the other feed apparatus.
A nozzle attachment 22, which is used for atomization of the emerging gas, can be provided in the area of the outlet end of the burner tube 3. This is indicated schematically by a dashed line in the drawing shown in
Number | Date | Country | Kind |
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102 43 739 | Sep 2002 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/DE03/03088 | 9/17/2003 | WO | 00 | 9/26/2005 |
Publishing Document | Publishing Date | Country | Kind |
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WO2004/028702 | 4/8/2004 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3141616 | Cauchetier | Jul 1964 | A |
4853513 | Fuimefreddo | Aug 1989 | A |
4937417 | Fox | Jun 1990 | A |
6076742 | Benary | Jun 2000 | A |
Number | Date | Country | |
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20060124762 A1 | Jun 2006 | US |