EP1423644A1

EP1423644A1 - Flame cutter and associated nozzle system suitable for slowly combustible and quickly combustible combustion gases

Info

Publication number: EP1423644A1
Application number: EP02776947A
Authority: EP
Inventors: Rainald Vossberg
Original assignee: Messer Cutting and Welding GmbH
Current assignee: Messer Cutting Systems GmbH
Priority date: 2001-09-07
Filing date: 2002-08-28
Publication date: 2004-06-02
Anticipated expiration: 2022-08-28
Also published as: PT1423644E; EP1423644B1; DE10144177B4; DE20216545U1; DK1423644T3; WO2003023278A1; ATE491116T1; ES2357813T3; DE50214805D1; DE10144177A1

Abstract

Disclosed is a flame cutter, comprising a burner head (1) connected to a cutting nozzle (2) which is encompassed by a heating nozzle (3) in the form of a cap. The cutting nozzle (2) has an outer covering with a radially revolving bearing surface (5). The heating nozzle (3) is provided with a radially revolving support surface (16) upon which the bearing surface (5) of the cutting nozzle (2) rests. In order to provide a flame cutter which can be used in a flexible manner especially in a blow-torch cutter machine fitted with nozzles which are both simple and compact and which are easy to maintain and service and which can be produced at low cost, the outer covering of the cutting nozzle (2) is embodied as a lower outer cylinder (7) downstream from the bearing surface (5) and the through-hole (17) of the heating nozzle (3) is cylindrical downstream from the support surface (16), being embodied as a radial guide for the lower outer cylinder (7). The inventive nozzle system comprises nozzles for slowly combustible combustion gases and for quickly combustible combustion gases. According to said system, storage costs for the wearing elements are low and the inventive nozzle system is characterised in that it comprises the heating nozzle (3) and several replaceable cutting nozzles (2a;2b) which are respectively designed for a combustion gas and a power range, all having a partial length adapted to a respective combustion gas between the bearing surface (5) and the nozzle exit (13).

Description

Patent application

Cutting torch and suitable nozzle system for slow-burning and for fast-burning fuel gases

The present invention relates to a cutting torch with a torch head which has a central axis and to which a metallic cutting nozzle is connected with an axial cutting oxygen line which is encompassed in a cap-like manner by a heating nozzle having an axial through-bore, the cutting nozzle having an outer jacket which is provided with longitudinal slots distributed around the circumference which extend from the lower, downstream end of the cutting nozzle via a cross-sectional widening provided upstream thereof and forming a radially circumferential bearing surface, and the heating nozzle in the region between its upper, upstream end and its nozzle outlet with a cross-sectional constriction forming a radially circumferential, upstream supporting surface is provided, on which the cutting nozzle rests with its contact surface.

Furthermore, the invention relates to a nozzle system for a cutting torch for - in connection with oxygen - slow-burning and for fast-burning fuel gases.

Different fuel gases are used in flame cutting technology, which can be divided into slow-burning and fast-burning fuel gases. The cutting torches of a flame cutting machine should advantageously be able to be operated with fuel gases of one or the other category if necessary. However, this usually requires changing the cutting torch nozzles. Cutting torches for slow-burning as well as cutting torches for fast-burning fuel gases are also frequently used on a flame cutting machine.

Ring or slot nozzles are predominantly used for flame cutting. These consist of two parts, the cutting nozzle and the heating cap or Heating nozzle. When changing the nozzles, they are screwed into the burner head together, one after the other or connected by means of a pressure screw, with a metallic seal.

The cutting process is carried out with a fuel gas heating oxygen flame and cutting oxygen. The cutting oxygen is fed to the cutting nozzle via an axial cutting oxygen line, while the fuel gas-oxygen mixture coming from a fuel mixture distribution chamber is fed to the heating nozzle, which surrounds the cutting nozzle in an annular gap. The heat emitted by the heating flame and the heat generated during the combustion of the workpiece enables continuous combustion by the cutting oxygen jet.

A cutting torch of the type mentioned is described in DE-T2 690 03 588. In the known cutting torch, the cutting nozzle is designed as a so-called slot nozzle. This is formed from a piece of metal that has an outer frustoconical shape with a wide upstream end and a narrower downstream end. The axial cutting oxygen line extends from the upper end to the nozzle outlet. On the outer circumference, the cutting nozzle has a series of radial ribs (longitudinal slots) which are formed by longitudinal milling in the metal body and which extend from the downstream end of the cutting nozzle to an outer collar provided on the upstream side, with which the cutting nozzle rests on a radial inner recess in the inner bore of the heating nozzle rests.

The heating nozzle is formed by a solid part with an inner bore which tapers conically towards the downstream end. The inner bore has the aforementioned radial inner recess in its upper region. The conical part of the inner bore, which begins downstream of it, is kept somewhat narrower than the envelope of the cutting nozzle ribs, so that it can be frictionally fixed in the heating nozzle by pressing in from above. The axial stop position results from the support of the outer collar and inner recess. The production of such conical contact surfaces in the heating and cutting nozzle requires a lot of effort to maintain the necessary dimensional accuracy.

During operation of the cutting torch, contamination occurs, in particular the cutting oxygen line, which leads to a deterioration in performance. Regular cleaning is therefore required, in which the nozzles must be completely disassembled. This has an adverse effect on the fit of the conical contact surfaces of the heating nozzle and cutting nozzle and can also damage the nozzles. Since the cutting nozzle is subject to greater wear, it would also be desirable to be able to replace it separately from the heating nozzle.

In addition, the use of the known cutting torch is limited to a short working distance between the nozzle and the workpiece surface in the range of 5 to 7 mm because of the taper of the nozzles.

In addition, depending on the thickness of the workpiece to be cut and the cutting parameters, the use of a slow-burning or a fast-burning fuel gas is necessary. In the known cutting torch, a selection of different cutting nozzles and matched heating nozzles must be available for this purpose, which is associated with a corresponding outlay for storage and changing the different nozzles.

Another cutting torch with a cutting nozzle in the form of a slot nozzle is described in DE 818482 and in DE 840 683 C. The cutting nozzle is formed from a piece of metal which has an outer frustoconical shape with a wider upstream end and a short, cylindrically tapering collar. The upper end of the cutting nozzle is provided with an external thread which is screwed gas-tight into a corresponding receptacle of the burner head, as a result of which the axial stop position of the cutting nozzle is predetermined.

The heating nozzle is made of a solid part with a cylindrical top, then tapering downwards and towards the lower end again cylindrical inner bore formed. The upper end of the heating nozzle is provided with an external thread, by means of which the heating nozzle is connected to the burner head in a gastight manner. This results in the axial fixation of the heating nozzle. The conical part of the inner bore is kept slightly narrower than the outer cone of the cutting nozzle, so that a gap remains between the heating nozzle and the cutting nozzle. There is also a clear gap between the collar of the cutting nozzle and the lower part of the inner bore of the heating nozzle, so that there is no contact between the cutting nozzle and the heating nozzle in this cutting torch.

However, the replacement of the cutting nozzle in this cutting torch is very complex. First the gas-tight screw connection of the heating nozzle and then that of the cutting nozzle must be opened. To accomplish this, sections of the nozzles are provided with hexagonal outer profiles that match wrenches. The production of the conical nozzle parts is complex and small dimensional deviations in the

Manufacturing or assembly lead to significant differences in the gap between the nozzles and thus to non-reproducible operating results. The tightness of the screw connection also suffers due to repeated nozzle changes.

A cutting torch with a cutting nozzle can be found in US 2,897,884, in which the heating nozzle and cutting nozzle are screwed together in a gas-tight manner. Furthermore, the cutting nozzle is attached to the torch head by means of a thread. The replacement of the cutting nozzle is also complex here.

A simplification of the tool change in flame cutting machines for oxyacetylene or plasma cutting, especially in machines with large ones

Portal width leads to reduced set-up times and thus to effective use of the machines as well as faster adaptability to changing production tasks. The changing of the nozzles is necessary, for example, if the nozzle has to be replaced by metal splashes or wear or if the cutting area of the nozzle does not match the thickness of the workpiece to be cut. DE-A1 3/35 598 describes a device for automatically changing cutting nozzles in an oxy-fuel cutting machine for oxy-fuel or plasma cutting, in which a machine control is provided by means of which the burners are moved to a nozzle bearing, the nozzle to be replaced being via a Unloading position positioned, solved there, then move the burner to a loading point and be equipped with a new nozzle. A coupling that works according to the quick-release principle is provided for holding the nozzles on the burners. For this purpose, a cutting nozzle and a heating nozzle surrounding the cutting nozzle in a cap-like manner are screwed to an adapter piece. The gas channels from the burner head to the heating nozzle and from the burner head to the cutting nozzle are located within this adapter piece and sealed to the outside by means of O-ring seals. When the coupling is opened, the adapter piece, including the heating nozzle or cutting nozzle screwed onto it, comes loose and is automatically exchanged by means of the changing device.

The known device provides for an automated change of the cutting torch nozzles, with the cutting nozzle and heating nozzle being exchanged in connection with the adapter piece.

The adapter piece causes a comparatively high overall height in the known cutting torch and its production is associated with additional costs.

The present invention is therefore based on the object of providing a cutting torch - in particular for a flame cutting machine - which enables simple and quick nozzle change and which is at the same time distinguished by a simple and compact construction which is associated with easy maintenance, simple maintenance and cost-effective production , and in addition, the effort for the storage of wear parts is reduced.

In addition, the invention is based on the object of specifying a nozzle system for the cutting torch according to the invention which comprises nozzles for slowly burning fuel gases and for rapidly burning fuel gases, and in which the expenditure for the storage of the wearing parts and the nozzle change is reduced.

With regard to the cutting torch, this object is achieved, based on the cutting torch mentioned at the outset, in that the outer jacket of the cutting nozzle downstream of the support surface is designed as a lower outer cylinder, and that the through hole of the heating nozzle downstream of the supporting surface is cylindrical and is designed as a radial guide for the lower outer cylinder

In the cutting torch according to the invention, the through bore of the heating nozzle is cylindrical at least in the longitudinal section downstream of the support surface up to the nozzle outlet. This cylindrical section of the heating nozzle is referred to below as the “inner cylinder”.

In addition, the outer jacket of the cutting nozzle is also cylindrical at least in the longitudinal section between its support surface and the nozzle outlet. In this length section, the cutting nozzle is provided with the longitudinal slots distributed on the outer circumference, the envelope of which is referred to as the “lower outer cylinder”.

The inner cylinder of the heating nozzle serves as a radial guide for the downstream end of the cutting nozzle. For this purpose, the heating nozzle surrounds the lower outer cylinder of the cutting nozzle with little radial play. On the one hand, this means that the cutting nozzle and heating nozzle can be detached from the torch head separately from one another with little effort and without the risk of damage to fitting or contact surfaces, and the guide contributes to the radial centering of the cutting nozzle.

By placing the cutting nozzle on the support surface of the heating nozzle, the two nozzles are also axially fixed to one another - without a mechanical connection between the cutting nozzle and the heating nozzle. A positive connection or a frictional metallic connection - such as the press fit between the heating nozzle and cutting nozzle in the known cutting torch mentioned at the outset not necessary, so that the nozzle change in the cutting torch according to the invention is easier overall.

Due to its design with an inner cylinder, the heating nozzle is suitable for use with different cutting nozzles, for example cutting nozzles for slowly burning fuel gases or for rapidly burning fuel gases. This is explained in more detail below: Cutting nozzles for slow-burning and cutting nozzles for fast-burning fuel gases differ in their axial distance between the nozzle outlets of the heating nozzle and cutting nozzle and in the cross-section of the heating nozzle for the fuel gas-oxygen mixture. In the cutting torch according to the invention, the distance is predetermined solely by the length of the respective lower outer cylinder of the cutting nozzle. The length of the lower outer cylinder can be exactly adjusted without great manufacturing effort; a complex adaptation of the inner cone and outer cone to one another is not necessary in the cutting torch according to the invention. When changing the fuel gases from fast-burning to slow-burning - or vice versa - the previous cutting nozzle can be replaced by a cutting nozzle adapted to the new requirements without having to replace the heating nozzle at the same time. The heating nozzle is suitable for use with any of the cutting nozzles in the nozzle system and can also be retained when the cutting nozzle is replaced. This reduces the variety of the nozzle shapes to be stored, simplifies storage and improves the operational safety of the cutting torch according to the invention by avoiding combinations of unsuitable nozzles.

In addition to the expanded application possibilities of the cutting torch according to the invention, the cylindrical nozzle shape - compared to conical nozzles - allows larger and more variable working distances between the nozzle and the workpiece surface; typically between about 15 to 20 mm.

The cutting torch according to the invention can be both a torch with external ignition and a torch with electrical internal ignition. The axial fixation of the cutting nozzle and the heating nozzle to one another in the cutting torch according to the invention results from the fact that the cutting nozzle is supported with its supporting surface on the contact surface of the heating nozzle. It has proven particularly useful if the support surface has a radially circumferential edge which rests on the support surface.

A particularly defined and always reproducible axial fixation of the cutting nozzle and heating nozzle is achieved by an edge. The edge can be designed as a terminating edge of a surface inclined to the central axis or a surface running perpendicular to the central axis (rectangular step). The last-mentioned embodiment variant can be manufactured more simply and more precisely, so that the peripheral edge is preferably formed as the outer end edge of a support surface extending perpendicular to the central axis. The support surface always runs parallel to the support surface.

It has proven to be particularly favorable if the cutting nozzle is provided with a funnel-shaped inlet for the cutting oxygen line. This reduces the degree of turbulence of the cutting oxygen when it enters the cutting nozzle and thus improves the reproducibility of the operating mode, in particular after a nozzle change.

In a particularly preferred embodiment of the cutting torch according to the invention, the outer jacket of the cutting nozzle is the upstream side of the

Support surface formed as an upper outer cylinder, the cylinder jacket surface provided with a sealing ring sealingly abuts a cutting nozzle receptacle of the torch head into which the cutting nozzle protrudes.

An adapter piece - as in the known cutting torch mentioned at the outset - is not necessary since the cutting nozzle is connected directly to the torch head. This enables a lower overall height and eliminates the manufacturing effort for the adapter piece.

In addition, the replacement of the cutting nozzle in the torch head is facilitated. The cutting oxygen line is sealed to the outside by means of the sealing ring and at the same time the Cutting nozzle fixed radially in the cutting nozzle holder. The cutting nozzle is pulled out of the cutting nozzle receptacle in the direction of the longitudinal axis with elastic deformation of the sealing ring, and vice versa - the upper end of the cutting nozzle is fixed by axially pressing it into the cutting nozzle receptacle. This type of mounting of the cutting nozzle requires little effort when changing the nozzle, since there is no need for a mechanical connection between the cutting nozzle and the torch head. In addition, an improved, more secure seal is achieved compared to a metallic seal via thread or cone.

The sealing ring is usually a ring made of elastic material which is in contact with the outer jacket or is inserted in an annular groove thereof.

The outer jacket of the cutting nozzle is both cylindrical in the length section between its support surface and the nozzle outlet (“lower outer cylinder”) and in the length section between the support surface and the upper end (“upper outer cylinder”). Due to its cylindrical shape, the

Cutting nozzle of the cutting torch according to the invention is particularly easy to manufacture.

It has proven particularly useful if the length of the upper outer cylinder is between 25 mm and 35 mm.

This measure results in a comparatively short length of the

Cutting nozzle, which facilitates a compact design of the cutting torch. This also contributes in particular if the cutting nozzle is held in the torch head by means of a sealing ring, as described above, and not, as is usual, by means of a threaded connection or pressure screw.

A further improvement results when the cutting nozzle in the

Cutting nozzle holder is held with axial play. The cutting nozzle is only fixed radially in the receptacle, while there is no axial stop position in the direction of the central axis. The axial play compensates for dimensional tolerances in the length of the cutting nozzle, so that they do not have any influence on the external dimensions of the cutting torch, nor do they increase any leaks. It is essential that the cutting nozzle lies in a defined manner on the support surface of the heating nozzle, which is ensured by the cutting oxygen pressure acting on the upper end face. This measure also simplifies the nozzle change and increases the operational reliability of the burner.

In connection with this, it has proven to be advantageous to provide the cutting nozzle with an outer edge rounded at its top end. The rounded outer edge facilitates the above-described axial insertion of the cutting nozzle into the cutting nozzle receptacle.

The large amounts of heat generated during oxyacetylene cutting in the front area of the nozzles must be removed as quickly as possible in order to avoid damage to the nozzles and to reduce wear. Metallic nozzle bodies with high thermal conductivity are therefore used. The sealing ring in the upper area of the cutting nozzle must therefore withstand high temperatures. It has therefore proven to be beneficial if

Cutting nozzle consists of a metal body, which is provided with a ceramic layer in the area of the adjacent sealing ring.

The sealing ring lies on a ceramic layer with poor thermal conductivity and is therefore shielded from the heat transported in the metal body and therefore less thermally stressed.

The ceramic layer can be designed as a separate component that is connected to the metal body in a gas-tight manner. However, the ceramic layer is preferably produced by coating, it having a thickness in the range between 5 μm and 25 μm. Coating processes simplify the production of a tight connection between the metal body and the ceramic layer.

A heating nozzle is preferably used in which the distance between the support surface and the lower end of the heating nozzle is between 6 mm and 10 mm. The distance limits mentioned result as a compromise between the requirements of a sufficient radial one Guiding the cutting nozzle in the "inner cylinder" of the heating nozzle and, on the other hand, a low overall height in order to provide a cutting torch that is as compact as possible.

In a particularly preferred embodiment of the cutting torch according to the invention, the heating nozzle has an outer jacket which is provided at the upper end with a sealing ring which lies sealingly against a heating nozzle receptacle formed in the torch head and into which the heating nozzle projects.

The gas mixture in the heating nozzle is sealed to the outside (against the atmosphere) by means of the sealing ring and at the same time the heating nozzle is radially fixed in the heating nozzle holder. For removal, the heating nozzle is pulled out of the heating nozzle receptacle in the direction of the longitudinal axis with elastic deformation of the sealing ring, and vice versa - the upper end of the heating nozzle is fixed by axially pressing it into the heating nozzle receptacle. In this embodiment of the cutting torch, in which the radial fixation and the sealing of the heating nozzle to the outside is carried out in a similar manner, as described above as advantageous for the cutting nozzle, there are advantages mentioned with regard to less effort when changing the nozzle and improved sealing.

It has proven useful to face the outer jacket of the heating nozzle downstream

Sealing ring with an outer collar, which rests with an upstream ring surface on an end ring surface of the burner head. The outer collar provided below the sealing ring results in a stop for the heating nozzle and thus a reproducible positioning in relation to the burner head.

The heating nozzle is preferably fixed to the burner head by means of a coupling which engages detachably on the outer jacket of the heating nozzle, the coupling having a through-bore with a radial cross-sectional constriction which engages under the outer collar of the heating nozzle. The coupling ensures on the one hand the positioning of the heating nozzle, and thus also indirectly the positioning of the cutting nozzle on the heating nozzle in relation to the burner head. To the others, a coupling - in particular a quick-release coupling - enables the nozzles to be released and mounted on the burner head in a particularly simple and quick manner. For this purpose, the coupling is detachably attached to the burner head on the one hand, and on the other hand it engages under the outer collar of the heating nozzle and fixes its position in relation to the burner head.

It has proven to be advantageous if the outer jacket of the heating nozzle is provided with a lower sealing ring which bears against the outer collar on the downstream side. In this case, the heating nozzle has a sealing ring above the outer collar and, axially offset below it, a second, lower sealing ring. This is pressed by the coupling under the outer collar against the downstream annular surface of the outer collar and thereby pushes the heating nozzle upwards against the burner head. This achieves, on the one hand, a play-free fixation of the heating nozzle on the burner head which compensates for manufacturing tolerances of the heating nozzle, and on the other hand a further sealing against the atmosphere.

In one embodiment of the cutting torch according to the invention with a nozzle holder by means of a detachable coupling, there is a further relief when changing the nozzle if the outer jacket of the heating nozzle is provided with a circumferential outer groove with an O-ring inserted therein, the inner groove provided downstream of the cross-sectional constriction in the inner bore of the coupling intervenes. The O-ring inserted in the circumferential outer groove engages in the inner groove of the coupling and forms a loose connection between the heating nozzle and coupling, so that when the coupling is released from the burner head, the heating nozzle slips out of the inner bore of the coupling both downwards and upwards is prevented. The two components - heating nozzle and coupling - can be pulled apart against the resistance of the O-ring.

An embodiment of the invention which is particularly suitable with regard to the overall height and the compact design of the cutting torch is that the torch head surrounds the cutting nozzle receptacle, coaxially by an annularly shaped heating nozzle receptacle, in which the upper end of the heating nozzle is sealed against the atmosphere. The nozzles are held directly on the burner head; Intermediate pieces are avoided.

Here, an embodiment has proven to be particularly favorable in which the cutting nozzle receptacle has an inner wall with an internal thread and a first radially circumferential, metallic sealing surface for the sealing receptacle of a cutting nozzle provided with an external thread and resting on the first sealing surface, and in which the Inner wall is provided with a second radially circumferential sealing surface for the sealing reception of a cutting nozzle with a sealing ring abutting the second sealing surface.

The burner head is in this case equipped with at least two different elements for establishing the connection with a cutting nozzle protruding into the first receptacle. One of the elements is an internal thread, which corresponds to an external thread of the cutting nozzle, a seal being usually produced to the outside by the contact force generated when screwing in between adjacent contact surfaces. The other element is a radially circumferential sealing surface, which forms a tight connection with a sealing ring of the cutting nozzle. As a result, the burner head can be used both for cutting nozzles that are provided with an external thread at their upper end and for those cutting nozzles that have a sealing ring (O-ring) at their upper end. In this respect, the torch head is designed to be multifunctional, which also contributes to reduced storage for the cutting nozzles and the associated lower manufacturing costs.

In addition or as an alternative to this embodiment of the cutting torch according to the invention, it has also proven useful if (also) the heating nozzle receptacle has an inner wall with an internal thread and a first radial, metallic sealing surface for the sealing receptacle of a heating nozzle provided with an external thread and resting on the first sealing surface and if the inner wall is provided with a second radially circumferential sealing surface for the sealing reception of a heating nozzle with a sealing ring abutting the second sealing surface. In this embodiment, the same advantageous result for the sealing holder of the heating nozzle on the burner head Effects on the flexibility of the burner head insert, as previously explained for the cutting nozzle.

The nozzles of the cutting torch according to the invention generally consist of stainless steel, brass or a temperature-resistant copper alloy. The heating nozzle can also be made of ceramic. With these metallic materials in particular, an improvement in wear resistance is achieved if the surface of the cutting nozzle and / or the surface of the heating nozzle has a hard material layer. This results in a longer service life for the nozzles and less maintenance. In particular, coatings made of metal nitrides or carbides, such as CrN, TiN, TiC, WC, come into consideration as the hard material layer.

With regard to the nozzle system for slow-burning and for fast-burning gases (in combination with oxygen) for a cutting torch according to the present invention, the technical problem specified at the outset is achieved according to the invention by a heating nozzle which is cylindrical in shape downstream of the supporting surface and a plurality of exchangeable heating nozzles, each designed for a fuel gas , downstream of the support surface, cylindrical cutting nozzles, with all cutting nozzles between the upper end and the support surface having an upper outer cylinder of the same partial length, and between the support surface and the nozzle outlet having a lower outer cylinder with a partial length matched to the respective fuel gas, such that there is a support surface resting on the support surface an axial distance between the nozzle outlet of the cutting nozzle and the nozzle outlet of the heating nozzle is set as a function of the respective fuel gas.

The cylindrical design of the heating nozzle (inner cylinder) and

Cutting nozzle (lower outer cylinder) in the area of the respective lower end are a prerequisite for the nozzle system according to the invention. Another requirement is that the inner cylinder of the heating nozzle serves as a radial guide for the lower outer cylinder of the cutting nozzle, as is explained in more detail above with reference to the description of the cutting torch according to the invention. Because the heating nozzle guides the lower outer cylinder of the cutting nozzle - that is, surrounds it with little radial play - it is possible to change the cutting nozzle with little effort and without the risk of damaging the mating or contact surfaces. The cylindrical design of the heating nozzle in the area of its “inner cylinder” makes it suitable for use with different cutting nozzles, for example cutting nozzles for slow-burning fuel gases or for fast-burning fuel gases. However, with the proviso that the cutting nozzles have a corresponding cylindrical design in the area of their “ lower outer cylinder "and moreover have the same length between the upper end and the support surface.

The same length for each cutting nozzle in the nozzle system ensures that the respective cutting nozzle exactly matches the configuration specified by the burner head and heating nozzle.

The partial length between the contact surface and the nozzle outlet corresponds to the length of the "lower outer cylinder". This length depends on the area of use of the respective cutting nozzle, which is particularly characterized by the type of fuel gas. Because the length of the lower outer cylinder determines the axial distance between the nozzle outlet Cutting nozzle and the nozzle outlet of the heating nozzle. This is lower with a fast-burning fuel gas than with a slow-burning fuel gas. The "nozzle outlet" runs in the plane of the lower edge of the respective nozzle.

The length of the lower outer cylinder can be exactly adjusted without great manufacturing effort; a complex adaptation of the inner cone and outer cone to one another is not necessary. The nozzle system according to the invention is characterized in that when the type of fuel gas is changed, the previous cutting nozzle is replaced by a cutting nozzle adapted to the new requirements, without the need to replace the heating nozzle. The heating nozzle is suitable for use with any of the cutting nozzles in the nozzle system and can also be retained when the cutting nozzle is replaced. This reduces the variety of the heater nozzle shapes to be stored, simplifies storage and improves the operational safety of the Cutting torch according to the invention by avoiding combinations of unsuitable nozzles.

With regard to the flexible use of the cutting torch and a low outlay for nozzle manufacture and storage, a nozzle system has proven particularly useful, with cutting nozzles in which the partial length of the lower outer cylinder is between 6 mm and 10 mm, in which the length of the upper outer cylinder in the Range is between 25 mm and 30 mm, and in which the partial length of the lower outer cylinder is selected as a function of the respective fuel gas and / or the power range such that there is an axial distance between the nozzle outlet of the cutting nozzle and the nozzle outlet when the support surface rests on the support surface the heating nozzle in the range between 0 mm and 3 mm.

Further improvements of the nozzle system according to the invention result from configurations of the cutting nozzles with the features of claims 2 to 5, 7, 9 and 10. Reference is made to the corresponding explanations for the cutting torch according to the invention.

The invention is explained in more detail below using an exemplary embodiment and a drawing. The drawings show in detail:

FIG. 1 shows a longitudinal section of a cutting nozzle for a cutting torch according to the invention,

FIG. 2 shows a longitudinal section of a heating nozzle for a cutting torch according to the invention,

FIG. 3 shows a longitudinal section of a torch head for a cutting torch according to the invention,

FIG. 4: an assembly drawing of a first embodiment of an assembled cutting torch according to the invention in a longitudinal section,

FIG. 5a: a longitudinal section of a cutting nozzle for rapidly burning gas, mounted in a heating nozzle, Figure 5b: a longitudinal section of a cutting nozzle for slowly burning gas, mounted in a heating nozzle, and

Figure 6 is an assembly drawing of a second embodiment of an assembled cutting torch according to the invention in a longitudinal section.

Figure 4 shows a first embodiment of an assembled cutting torch according to the invention. This is part of a flame cutting machine for oxyfuel cutting. The cutting torch essentially consists of a burner head 1, which is connected to a cutting nozzle 2 and to a heating nozzle 3 encompassing the cutting nozzle 2 by means of a coupling 4. The structural features of the individual components and their function are explained in more detail below with reference to FIGS. 1 to 3 and the assembly drawing according to FIG.

The cutting nozzle 2 according to FIG. 1 consists of a substantially cylindrical brass part which is rotationally symmetrical about the central axis 15 and which is provided with a hard material layer made of chromium nitride (CrN). The outer jacket of the cutting nozzle 2 has two cylindrical longitudinal sections, which differ in their diameter, and which are connected by a circumferential rectangular step 5 with a support surface facing downstream and perpendicular to the central axis 15 and having a defined, circumferential end edge 25. In the upper upstream length section 6 (upper outer cylinder) the outer diameter is 8 mm, in the lower downstream length section 7 (upper outer cylinder) the outer diameter is 6 mm. The cutting nozzle 2 is part of the nozzle system according to the invention, which comprises a plurality of interchangeable cutting nozzles, each of which is designed for a specific fuel gas and a predetermined output range. With all nozzles of this nozzle system, the upper outer cylinder 6 has a length of 30 mm. The length of the lower outer cylinder 7 is decisive for the suitability of the cutting nozzle with regard to the type of fuel gas. In the cutting nozzle 2, which is designed for fast-burning fuel gas, the length of the lower outer cylinder 7 is 8 mm. The lower outer cylinder 7 and the part of the upper outer cylinder 6 adjoining it are provided with a plurality of axial longitudinal slots 8, which are evenly distributed over the circumference of the outer jacket and which extend over the step 5. The longitudinal slots 8 serve to supply a fuel gas / oxygen mixture for the outlet of the heating nozzle (see FIG. 4).

At the upper end of the cutting nozzle 2, the outer jacket has a circumferential groove which is used to receive an O-ring 9 made of a heat-resistant material, e.g. Silicone, is provided.

The front outer edge 10 at the upper end of the cutting nozzle 2 is rounded and protrudes into an inner bore 30 of the burner head 1, on the inner wall of which the O-ring 9 lies sealingly.

The cutting oxygen line 11 is sealed to the outside by means of the O-ring 9 and at the same time the cutting nozzle 2 is radially fixed within an inner bore 30 of the torch head 1 (FIG. 4). An axial end stop for the cutting nozzle in the inner bore 30 is dispensed with, so that dimensional tolerances in the length of the cutting nozzle can be absorbed by axial play. The axial position of the cutting nozzle 2 is determined solely by the defined support on a support step 16 of the heating nozzle 3 (see FIG. 4), which is ensured by the cutting oxygen pressure acting on the upper end face 10. This type of mounting of the cutting nozzle 2 - directly on the torch head and without mechanical connection - requires little effort when changing the nozzle and, in addition, a low overall height and an improved seal compared to a metallic seal are achieved.

The cutting oxygen channel 11, which is designed in the form of a Laval nozzle, runs in the central axis 15 of the cutting nozzle 2. The nozzle inlet 24 narrows in a funnel shape from top to bottom in order to ensure a low-turbulence gas inlet. After the nozzle inlet, the cutting oxygen channel 11 narrows in the form of an inner cone 12 in the upper end of the cutting nozzle 2 and opens into the lower end of the cutting nozzle 2 as a more or less cylindrical inner bore (Laval nozzle) at the nozzle outlet 13. The heating nozzle 3 shown in Figure 2 is made of copper. It is also rotationally symmetrical about the central axis 15 and provided with a hard material layer made of CrN. The heating nozzle 3 is suitable for receiving a cutting nozzle 2 according to FIG. 1. For this purpose, the through-bore 17 of the heating nozzle 3 in the area between its upper, upstream end and the nozzle outlet 14 has a radially circumferential, upwardly directed support step 16, on which the cutting nozzle 2 rests with its downstream contact surface of step 5 (FIG. 4). The through hole 17 is cylindrical below the support step 16 with an inner diameter of slightly more than 6 mm. The cylindrical length section marked with the reference number 18 has a length of 10 mm and serves as a radial guide for the lower outer cylinder 7 of the cutting nozzle 2 without forming a coherent connection. This enables the cutting nozzle 2 and heating nozzle 3 to be replaced separately.

The outer jacket of the heating nozzle 3 has a cone 19 which tapers towards the nozzle outlet and merges upwards into an essentially cylindrical length section 20. At the upper end of the length section 20 there is a circumferential groove with an O-ring 21 made of silicone, which lies sealingly against the inner wall of an annular groove 33 in the burner head 1 (FIG. 4).

The supply line 26 (see FIG. 4) for the fuel-oxygen mixture is sealed from the atmosphere by means of the O-ring 21, and at the same time the heating nozzle 3 is fixed radially within the annular groove 33 of the burner head 1 (FIG. 4). This type of fixation of the heating nozzle 3 requires little effort when changing the nozzle and, in addition, a low overall height and an improved seal compared to a metallic seal are achieved.

A circumferential outer collar 22 is provided downstream of the O-ring 21, the upper side of which rests in the mounted cutting torch against an annular surface of the torch head 1 directed downward (see FIG. 4). The coupling 4 attached to the burner head 1 engages on the underside of the outer collar 22, as will be described in more detail below. Another O-ring 38 rests on the outer jacket of the heating nozzle 3 and on the underside of the outer collar 22. This is pressed by the coupling 4 under the outer collar 22 against the underside of the outer collar 22 and thereby presses the heating nozzle 3 upwards, against the burner head 1. The two axially offset O-rings 21, 38 prevent the heating nozzle 3 from tilting and manufacturing tolerances of the heating nozzle 3 are compensated.

In order to facilitate a nozzle change, a loose connection is generated between the heating nozzle 3 and the coupling 4, which prevents the heating nozzle 3 from slipping out of the inner bore of the coupling 4 both downwards and upwards when the coupling 4 is released from the burner head 1. For this purpose, a circumferential milling 23 is provided on the outer jacket of the heating nozzle 3 below the outer collar 22, into which an O-ring 29 is inserted, which - as FIG. 4 shows - engages in a corresponding inner groove in the coupling 4. The heating nozzle 3 and coupling 4 can only be pulled apart against the resistance of the O-ring 29.

Figure 3 shows an embodiment of a torch head 1 for the cutting torch according to the invention. This consists of an essentially cylindrical brass component in which the connecting line 25 for the cutting oxygen and the connecting line 26 for the fuel gas / oxygen mixture run, and on the outer jacket of which the coupling 4 by means of ball traps 27, 28, the heating nozzle 3 and the cutting nozzle 2 are releasably attached (Figure 4).

For this purpose, the lower part of the torch head 1 facing the nozzles (2, 3) is provided with a central inner bore 30 which forms part of the connecting line 25 and which also serves as a receptacle for the upper end of the cutting nozzle 2. For this purpose, the inner bore 30 is provided with a radial metallic sealing surface 32. An internal thread 31 is additionally provided above it. Thus, the burner head 1 is suitable both for receiving a cutting nozzle with a standard external thread matching the internal thread 31 and for sealingly receiving a cutting nozzle 2 which is provided with an O-ring 9 abutting the sealing surface 32 (as above with reference to FIG 1 described). For the axial fixation of the cutting nozzle 2 with O-ring 9 on In the area below the internal thread 31, the burner head 1 is provided with a cross-sectional constriction against which the end face of the cutting nozzle 2 bears in the installed state (see FIG. 4).

Furthermore, the lower part of the burner head 1 is provided with an annular groove 33 beginning at the lower end of the burner head, into which the connecting line 26 opens and which at the same time forms a receptacle for the upper end of the heating nozzle 3. For this purpose, the annular groove 33 is provided with a radial metallic sealing surface 35, and above it also with an internal thread 34. The burner head 1 is therefore suitable both for receiving a heating nozzle with an external thread matching the internal thread 34 and for sealingly receiving a heating nozzle 3 which is provided with an O-ring 21 abutting the sealing surface 35 (as described above with reference to FIG. 2). The outer collar 22 of the heating nozzle 3 serves to axially fix the heating nozzle 3 to the torch head 1, in that the top side thereof in the mounted cutting torch bears against an end face 36 of the torch head 1 (see FIG. 4). The sealing surface 32 and 35 for receiving a nozzle 3, 4 with an O-ring 9, 21 is arranged downstream of the respective internal thread 31, 34.

The burner head 1 thus has two alternative elements for establishing the connection with a cutting nozzle projecting into the inner bore 30 and a heating nozzle 3 projecting into the annular groove 33. Namely, an internal thread 31, 34 which corresponds to a corresponding external thread of the cutting nozzle or heating nozzle, and in each case a radially circumferential sealing surface 32, 35 against which the O-ring 9 on the outer jacket of the cutting nozzle 3 and the O-ring 21 on the outer jacket the heating nozzle 3 rests sealingly.

As a result, the burner head 1 can be used both for those nozzles which are provided with an external thread at their upper end and for those nozzles which - as provided in this exemplary embodiment - have a sealing ring (O-ring 9 or 21) at their upper end. exhibit.

In addition to the components of the cutting torch according to the invention described so far, the construction and function of the coupling 4 can be seen from the assembly drawing according to FIG. This essentially consists of an inner ring 40 fixed to the burner head 1 by means of a ball trap 27, 28, which with a radial cross-sectional constriction 42 engages under the outer collar 22 of the heating nozzle 3 and fixes it in its axial position. The inner ring 40 is surrounded by an outer ring 41 which can be displaced upward along the inner ring 40 against an axially downward spring force by loosening the ball latch 27, 28. The coupling 4 enables the nozzles 2, 3 to be changed quickly. The type of sealing and holding of the nozzles 2, 3 on the burner head 1 by means of an O-ring seal also contributes to this.

The heating nozzle 3 described with reference to FIG. 2 is suitable both for receiving cutting nozzles for rapidly burning fuel gas and for receiving cutting nozzles for slowly burning fuel gases. This is shown in Figures 5a and 5b.

The cylindrical design of the heating nozzle 3 (see FIG. 2) in the area of the inner cylinder 18 makes it suitable for use with different cutting nozzles. However, this requires that the

Cutting nozzles have a corresponding cylindrical design in the area of the outer cylinder 7 (FIG. 1) and moreover in the upper upstream length section 6 the same partial length. This is the case with the cutting nozzles 2a (FIG. 5a) and 2b (FIG. 5b). The cutting nozzles 2a, 2b thus fit exactly to the configuration specified by the burner head 1 and heating nozzle 3.

The cutting nozzles 2a, 2b differ only in the length of the respective outer cylinder and in the flow cross sections of the nozzle slots. In the cutting nozzle 2a, which is designed for fast-burning fuel gas, the length of the outer cylinder 7a is 8 mm, and in the cutting nozzle 2b, which is designed for slow-burning fuel gas, the outer cylinder 7b has a length of 7 mm. This results in an axial distance of 0 mm between the lower edge of the heating nozzle 3 (nozzle outlet 14) and the lower edge of the cutting nozzle 2a (nozzle outlet 13) and between the lower edge of the heating nozzle 3 (nozzle outlet 14) and the lower edge of the cutting nozzle 2b (nozzle outlet 13) an axial distance (reference number 50) of 1 mm. When changing the type of fuel gas, the previous cutting nozzle can be replaced by a cutting nozzle adapted to the new requirements, without the need to replace the heating nozzle. The heating nozzle is suitable for use with any of the cutting nozzles in the nozzle system and can also be retained when the cutting nozzle is replaced. This reduces the variety of the nozzle shapes to be stored, simplifies storage and improves the operational safety of the cutting torch according to the invention by avoiding combinations of unsuitable nozzles.

In another embodiment of the cutting torch according to the invention, a coupling in the form of a bayonet lock is provided for connecting the heating nozzle and cutting nozzle to the torch head. Compared to the ball trap shown in FIG. 4, the bayonet connection offers greater security against unintentional opening, but requires somewhat more effort for automating the nozzle change.

FIG. 6 shows such a second embodiment of the cutting torch for an oxyacetylene cutting machine. If identical reference numerals are used here as in FIGS. 1 to 4 and 5a and 5b, the same or equivalent components and components are used, as are explained in more detail above with reference to the description of the first embodiment of the cutting torch according to the invention. For reasons of a clearer illustration, the connecting line for the fuel gas / oxygen mixture is not shown in FIG. 6.

The cutting torch differs from the cutting torch according to FIG. 4 essentially in the type of connection of the nozzles to the torch head 1. The cutting torch consists of a torch head 1 which has a cutting nozzle 2 and a heating nozzle 3 which surrounds the cutting nozzle 2 by means of a coupling 61 is connected in the form of a bayonet catch. The bayonet catch is essentially formed by two screw heads 62 which lie opposite one another on the burner head 1 and protrude from the burner head 1, the outer ring 41 and a milling 63 running around the inside of the outer ring 41. When the burner head 1 is put on, the screw heads 62 are inserted into one in FIG schematically indicated connecting groove 64 introduced to the milling 63 and locked therein by a quarter turn.

The cutting torch shows a further modification compared to the first embodiment explained above, namely with regard to the cutting nozzle. The cutting nozzle 2 consists of a rotationally symmetrical, essentially cylindrical brass part which is provided with a hard material layer made of nickel carbide (NiC). The only modification compared to the cutting nozzle described with reference to FIG. 1 is that a 20 μm thick and 5 mm wide ceramic layer 66 is provided in the area of the groove for the O-ring 9. The ceramic layer 66 reduces the heat conduction to the O-ring 9 and thus improves the long-term stability of the seal.

Claims

claims

1. Cutting torch with a torch head having a central axis, to which a metallic cutting nozzle with an axial cutting oxygen line is connected, which has an axial through bore

The nozzle is encompassed in a cap-like manner, the cutting nozzle having an outer jacket which is provided with circumferentially distributed longitudinal slots which extend from the lower, downstream end of the cutting nozzle via a cross-sectional widening provided upstream thereof and forming a radially circumferential bearing surface, and the heating nozzle in

The area between its upper, upstream end and its nozzle outlet is provided with a cross-sectional constriction forming a radial circumferential, upstream side support surface, on which the cutting nozzle rests with its supporting surface, characterized in that the outer jacket of the cutting nozzle (2) downstream of the supporting surface (5) as lower outer cylinder (7), and that the through hole (17) of the heating nozzle (3) downstream of the support surface (16) is cylindrical and is designed as a radial guide for the lower outer cylinder (7).

2. Cutting torch according to claim 1, characterized in that the bearing surface (5) has a radially circumferential edge (25) on the

Support surface (16) rests.

3. Cutting torch according to claim 2, characterized in that the peripheral edge (25) is formed as the outer end edge of a support surface (5) extending perpendicular to the central axis (15).

4. Cutting torch according to one of the preceding claims, characterized in that the cutting nozzle (2) is provided with a funnel-shaped inlet (26) for the cutting oxygen line (11).

5. Cutting torch according to one of the preceding claims, characterized in that the outer jacket of the cutting nozzle (2) upstream of the mounting surface (5) is designed as an upper outer cylinder (6), the Cylinder surface with a sealing ring (9) provided on a cutting nozzle receptacle (30) of the torch head (1) into which the cutting nozzle

(2) protrudes, fits tightly.

6. Cutting torch according to claim 5, characterized in that the cutting nozzle (2) in the cutting nozzle receptacle (30) is held with axial play.

7. Cutting torch according to one of the preceding claims, characterized in that the cutting nozzle (2) is formed at its upper end with a rounded outer edge (10).

8. Cutting torch according to one of the preceding claims, characterized in that the distance between the support surface (16) and the lower end of the heating nozzle (3) is between 6 mm and 10 mm.

9. Cutting torch according to one of the preceding claims, characterized in that the cutting nozzle consists of a metal body which is provided in the region of the adjacent sealing ring (9) with a ceramic layer.

10. Cutting torch according to claim 9, characterized in that the ceramic layer has a thickness in the range between 5 microns and 25 microns and is produced by coating.

11. Cutting torch according to one of the preceding claims, characterized in that the heating nozzle (3) has an outer jacket which is provided at the upper end with a sealing ring (21) which is formed on a heating nozzle receptacle (33) formed in the torch head (1). into which the heating nozzle

(3) protrudes, rests sealingly, the outer jacket of the heating nozzle (3) being provided downstream of the sealing ring (21) with an outer collar (22) which rests with an upstream ring surface on an end ring surface (36) of the burner head (1).

12. Cutting torch according to claim 12, characterized in that the heating nozzle (3) engages by means of an on the outer jacket of the heating nozzle (3) Coupling (4; 61) is detachably fixed to the burner head (1), the coupling (4; 61) having a through-hole with a radial cross-sectional constriction (42) which engages under the outer collar (22) of the heating nozzle (3).

13. Cutting torch according to claim 12 or 13, characterized in that the outer jacket of the heating nozzle (3) is provided with a lower sealing ring (38) lying downstream on the outer collar (22).

14. Cutting torch according to one of claims 13 to 14, characterized in that the outer jacket of the heating nozzle (3) is provided with a circumferential outer groove (23) with an O-ring (29) inserted therein, which in a downstream of the cross-sectional constriction (42) provided

Inner groove engages in the inner bore of the coupling (4; 61).

15. Cutting torch according to one of the preceding claims, characterized in that the cutting nozzle receptacle (30) is coaxially surrounded by an annular gap-shaped heating nozzle receptacle (33), in which the upper end of the heating nozzle (3) is received sealingly to the outside.

16. Cutting torch according to claim 15, characterized in that the cutting nozzle receptacle (30) has an inner wall with an internal thread (31) and a first radially circumferential, metallic sealing surface for the sealing reception of a cutting nozzle provided with an external thread and resting on the first sealing surface , and that the inner wall is provided with a second radially circumferential sealing surface (32) for the sealing reception of a cutting nozzle (2) with a sealing ring (9) resting on the second sealing surface.

17. Cutting torch according to claim 14 or 15, characterized in that the heating nozzle receptacle (33) has an inner wall with an internal thread (34) and a first radial, metallic sealing surface for the sealing reception of an externally threaded heating nozzle which is in contact with the first sealing surface and that the inner wall with a second radially circumferential sealing surface (35) for the sealing reception of a The heating nozzle (3) is provided with a sealing ring (21) resting on the second sealing surface (35).

18. Cutting torch according to one of the preceding claims, characterized in that the surface of the cutting nozzle (2) and / or the surface of the heating nozzle (3) has a hard material layer.

19. Nozzle system for a cutting torch for slow-burning and for fast-burning gases according to one of the preceding claims, characterized by the cylinder-shaped heating nozzle (3) downstream of the support surface (16) and a plurality of interchangeable, each designed for a fuel gas, downstream of the support surface (5 ) cylindrical cutting nozzles (2a; 2b), the cutting nozzles (2a; 2b) between the upper end and the support surface (5) having an upper outer cylinder (6) of the same length, and between the support surface (5) and nozzle outlet (13) a lower outer cylinder ( 7) with a partial length matched to the respective fuel gas, in such a way that when it rests on the support surface (16)

Contact surface (5) sets a predetermined axial distance (50) between the nozzle outlet (13) of the cutting nozzle (2) and the nozzle outlet (14) of the heating nozzle (3) as a function of the respective fuel gas.

20. Nozzle system according to claim 18, characterized in that the partial length of the lower outer cylinder (7) is between 6 mm and 10 mm, that the

The length of the upper outer cylinder (6) is in the range between 25 mm and 30 mm, and that the partial length of the lower outer cylinder (7) is selected as a function of the respective fuel gas and / or the power range in such a way that when on the support surface (16) bearing surface (5) an axial distance (50) between the nozzle outlet (13) of the cutting nozzle (2) and the

Nozzle outlet (15) of the heating nozzle (3) results in a range between 0 mm and 3 mm.