Protective nozzle cap, plasma arc torch comprising said protective nozzle cap, and use of the plasma arc torch

Abstract

In the case of the nozzle protection cap (7) according to the invention for a plasma arc torch (1), is arranged and fastened at the outside on the tip of the plasma arc torch (1), at which a plasma jet emerges from the plasma arc torch (1) through nozzle-like openings (4a, 7a). The nozzle protection cap (7) is produced from an iron alloy including sulfur in a fraction of at least 0.05%.

Claims

1. A nozzle protection cap for a plasma arc torch, which nozzle protection cap is arranged and fastened at the outside on the tip of the plasma arc torch, at which a plasma jet emerges from the plasma arc torch through nozzle-like openings; wherein the nozzle protection cap is produced from an iron alloy including sulfur in an amount of at least 0.05% and cobalt in the amount of less than 0.1%.

2. The nozzle protection cap as claimed in claim 1, wherein the iron alloy includes sulfur in an amount in the range from 0.05% to 0.5%.

3. The nozzle protection cap as claimed in claim 1, wherein aside from the sulfur, there is at least one further additional alloy element selected from chromium, nickel, manganese, molybdenum, niobium, titanium, tungsten or vanadium.

4. The nozzle protection cap as claimed claim 3, wherein one or more additional alloy elements is/are included in an amount of at most 35%.

5. The nozzle protection cap as claimed in claim 4, wherein either chromium and nickel are included as additional alloy elements.

6. The nozzle protection cap as claimed in claim 1, wherein either no carbon is included, or carbon is included in a maximum amount of 2.1%.

7. The nozzle protection cap as claimed in claim 1, wherein the iron alloy has a thermal conductivity of at least 10 W/m*K, a hardness of at least HB 150, or is oxidation-resistant and corrosion-resistant under normal ambient or usage conditions.

8. A plasma arc torch having a torch body, having an electrode arranged in the torch body, having a nozzle which has a central nozzle opening and which is arranged so as to cover the electrode in a manner separated by a plasma gas channel formed between the nozzle and the electrode, a nozzle protection cap which has an outlet opening, arranged at the front end side of the nozzle protection cap and situated opposite the control nozzle opening, and a ring-shaped secondary gas channel within the nozzle protection cap, which ring-shaped secondary gas channel is connected to the outlet opening, wherein the nozzle protection cap is arranged so as to be electrically insulated with respect to the electrode and the nozzle, and a secondary gas guide part, which has at least one passage, the nozzle protection cap is detachably fastened to the plasma arc torch, wherein the nozzle protection cap is designed as claimed in claim 1.

9. The nozzle protection cap as claims in claim 1, wherein the inner alloy includes sulfur in an amount in the range of from 0.1% to 0.4% and a maximum amount of carbon of 1.2%.

10. The nozzle protection cap as claimed in claim 1, wherein the inner alloy includes Sulphur in the range of from 0.15% to 0.35% and a maximum amount of carbon of 0.5%.

Description

DESCRIPTION OF THE DRAWINGS

(1) The invention will be discussed in more detail by way of example below.

(2) In the FIGURE:

(3) FIG. 1 shows a sectional illustration through a plasma arc torch with a nozzle protection cap according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) FIG. 1 shows a plasma torch 1 according to a particular embodiment of the invention. The plasma torch 1 has a torch body 2 with an electrode 3 and a nozzle 4, which are of substantially rotationally symmetrical form about the longitudinal axis L of the plasma torch 1. The electrode 3 and the nozzle 4 are arranged coaxially in the torch body 2, are situated in a particular spatial relationship, and form a plasma chamber 6, through which there flows a plasma gas PG which is fed via a plasma gas channel 6a. A nozzle cap 5 is arranged coaxially with respect to the longitudinal axis L of the plasma torch 1, and holds and surrounds the nozzle 4 with a protective action. Between the nozzle 4 and the nozzle cap 5, there is situated a chamber 11 through which cooling water flows. The cooling water is fed via a water feed WV and flows out via a water return WR.

(5) A ring-shaped secondary gas guide part 8 with a multiplicity of passages, in particular in the form of bores, of which only one is denoted by the reference designation 8a, is arranged in a secondary gas channel 9 formed between the nozzle cap 5 and a nozzle protection cap 7, between a secondary gas inlet 8b and the front end of the secondary gas channel 9, such that the secondary gas SG flowing through the passages 8a impinges on the outer shell surface of the nozzle cap 5. The secondary gas SG is subsequently conducted through the secondary gas channel 9, which is delimited by the shell surface of the nozzle cap 5 and by the inner surface 7b of the nozzle protection cap 7, to the front end of the plasma torch 1, is then fed to a plasma jet (not shown), and emerges through an outlet opening 7a of the nozzle protection cap 7. The rotating secondary gas SG flows around the plasma jet after it emerges from a nozzle opening 4a, and additionally creates a defined atmosphere around the plasma jet.

(6) The passages 8a of the secondary gas guide part 8 are arranged such that a rotating flow of the secondary gas SG is realized. For example, the passages 8a in the secondary gas guide part 8a may be arranged equidistantly over the circular circumference of the secondary gas guide part 8 and so as to extend radially or with an offset with respect to the radial, that is to say so as to be oriented toward a point in each case offset with respect to the actual circle central point.

(7) It is also possible for the torch to have no nozzle cap 5, and for the nozzle 4 to be screwed into the torch body 2, for example. Then, the chamber 5 through which the secondary gas SG flows is delimited by the shell surface of the nozzle 4 and by the inner surface 7b of the nozzle protection cap 7.

(8) In the case of this plasma arc torch, use may, according to the invention, be made of a nozzle protection cap 7 as claimed in any of claims 1 to 8. In a specific individual example, the nozzle protection cap 7 may be composed of an alloy which has been produced with iron and additionally 17 to 19% chromium, 8% to 10% nickel and 0.15% to 0.35% sulfur. The maximum carbon fraction may amount to 0.1%.

REFERENCE DESIGNATIONS

(9) 1 Plasma torch 2 Torch body 3 Electrode 4 Nozzle 4a Nozzle opening 5 Nozzle cap 6 Plasma chamber 6a Plasma gas channel 7 Nozzle protection cap 7a Outlet opening 7b Inner surface 8 Secondary gas guide part 8a Passage 8b Secondary gas inlet 9 Secondary gas channel L Longitudinal axis PG Plasma gas SG Secondary gas WV Water feed WR Water return