Method for flame straightening and burner assembly for this purpose

Abstract

A method for flame straightening is disclosed, wherein acetylene with oxygen is combusted by means of a burner to yield a flame, and the flame is directed onto a workpiece so as to heat the workpiece, wherein an electric field is applied between the burner and the non-melting workpiece which is electrically conductive, or the electric field is applied between the burner and a non-melting electrode arranged on the non-melting workpiece side to reduce NOx emission.

Claims

1. A method for flame straightening, said method comprising: combusting acetylene with oxygen by means of a burner to yield a flame, directing the flame onto a non-melting workpiece so as to subject the workpiece to flame straightening wherein the workpiece is locally heated in a targeted manner into the plastic range to straighten warpage, distortion, bending and/or twisting, and applying an electric field between the burner and the non-melting workpiece, wherein the non-melting workpiece is electrically conductive, to reduce NOx emission, or applying an electric field between the burner and a non-melting electrode arranged on the non-melting workpiece side to reduce NOx emission.

2. The method according to claim 1, wherein a direct voltage field is used as the electric field.

3. The method according to claim 2, wherein a polarity on the burner side is negative.

4. The method according to claim 1, wherein an alternating voltage field is used as the electric field.

5. The method according to claim 4, wherein, on the burner side, positive phases of the alternating current are shorter than the negative phases.

6. The method according to claim 1, wherein the electric field is generated by means comprising at least one electric line to the burner.

7. The method according to claim 1, wherein the electric field is generated by at least one battery arranged in or on the burner, and at least one electric line to the electrode or to the electrically conductive workpiece.

8. The method according to claim 1, wherein said method comprises applying an electric field between the burner and the non-melting workpiece, wherein the non-melting workpiece is electrically conductive.

9. The method according to claim 8, wherein the electric field is generated by (a) at least one electric line to the burner and (b) at least one electric line to the electrically conductive workpiece.

10. The method according to claim 1, wherein said method comprises applying an electric field between the burner and a non-melting electrode arranged on the non-melting workpiece side.

11. The method according to claim 10, wherein the electrode is arranged between the burner and the workpiece and the electrode has an annular shape.

12. The method according to claim 11, wherein the electric field is generated by (a) at least one electric line to the burner and (b) at least one electric line to the electrode.

13. The method according to claim 10, wherein the electric field is generated by (a) at least one electric line to the burner and (b) at least one electric line to the electrode.

14. The method according to claim 1, wherein the electric field is generated by means comprising at least one electric line to the electrode or to the electrically conductive workpiece.

15. The method according to claim 1, wherein the electric field is generated by (a) at least one electric line to the burner and (b) at least one electric line to the electrically conductive workpiece.

16. The method according to claim 1, wherein the electric field is generated by (a) at least one electric line to the burner and (b) at least one electric line to the electrode.

17. The method according to claim 1, wherein a current is measured between the burner and the electrode on the workpiece side or between the burner and the workpiece and using the measured current to determine whether a flame is present.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically depicts a first embodiment of a burner assembly for flame straightening.

(2) FIG. 2 schematically depicts a second embodiment of a burner assembly for flame straightening.

DETAILED DESCRIPTION OF THE INVENTION

(3) FIG. 1 presents a schematic view of a first embodiment of a burner assembly for flame straightening with a burner 20 having an oxygen supply 22 and an acetylene supply 21. The means for directing the flame 25 generated by the burner 20 onto a workpiece are here not separately shown. Such an acetylene burner is itself known from prior art.

(4) In order to reduce NOx emissions in the area of the secondary flame in the edge area of the flame 25, an electric field is generated between the burner 20 and the non-melting workpiece 10, which in this exemplary embodiment is electrically conductive or at least coated with an electrically conductive layer. A voltage source 23 is provided to this end, whose first pole is connected with the burner 20 by a line 26, and whose second pole is connected with the workpiece 10 by a line 28. NOx emissions can be greatly reduced by setting a suitable field strength of the electric field by setting a voltage on the voltage source 23. In specific tasks with heat- or surface-sensitive components, an operation with pulsed current or targeted alternating current portions can be advantageous.

(5) FIG. 2 shows a second embodiment of a burner assembly for flame straightening, once again with a burner 20 and an oxygen supply 22 and an acetylene supply 21, and with means not depicted for directing a flame 25 generated by the burner 20 onto a workpiece 10. In the exemplary embodiment according to FIG. 2, this workpiece is not electrically conductive, or applying a direct voltage to the workpiece 10 is problematic. In this case, the electric field is applied between the burner 20 and a non-melting electrode 24 arranged on the workpiece side. The electrode 24 is thus arranged between the burner 20 and workpiece 10 in the area of the flame 25. An annular electrode 24 is especially expedient for determining the areas of elevated NOx formation with the generated electric field, and there reducing the NOx emission.

(6) A voltage source is once again provided for generating the electric field, which is connected with the burner 20 by a first line 26, and with the electrode 24 by a second line 27. In this exemplary embodiment, the electrode 24 is mechanically joined with the burner 20, wherein the connection is established via an insulation section 29.

(7) In the depicted embodiments according to FIGS. 1 and 2, the voltage can also be supplied via a battery arranged in or on the burner 20, whose poles are correspondingly joined with the burner housing and the electrode 24 or workpiece 10.