EP0961527A1 - Welding torch - Google Patents

Abstract

The torch (10) consists of main body (12) which accommodates a sleeve (20) for an electrode (48). The electrode is adjoined with a nozzle (34) which is covered by a shield cup (36). A cylinder (60) and a piston (82) are accommodated inside the main body. The gas inlet passage (94) is provided in the main body. An outlet orifice (104) for plasma gas (P) is provided in an edge wall (102) of the nozzle. While passing out the outlet orifice, an arc is provided between the electrode and the nozzle. A swirling rib (130) is provided inside edge wall of the nozzle for guiding flow of plasma gas from inlet to outlet orifice.

Description

The present invention relates to a plasma torch or Plasma arc welding torch and refers here particularly on improvements in gas flow to Cooling and operating the burner.

Plasma arc welding torches usually have an electrode and a nozzle element in which the working tip of the Electrode is supported so that the end face of the electrode a head wall of the nozzle element having a plasma outlet opening opposite. The electrode and the nozzle element can be relative to each other between a position in which the Electrode touches the head wall of the nozzle element, and one Position in which the electrode is a working distance from the head wall is spaced, movable so that a pilot arc can be generated if the electrode is from the Head wall moved away to their working position. Alternatively, you can the electrode and the nozzle element are also stationary relative to one another be, the welding torch then using high frequency or other known starting process is ignited. In all embodiments, the head wall and the head surface form the electrode a gas space, which a plasma or arc gas is supplied and from which a plasma jet through the Exhaust port exits when between the electrode and the Nozzle element an arc current flows. When starting the Welding torch, this operates in a mode in which the Arc is not transferred to the workpiece; if that Nozzle element is brought into the vicinity of a workpiece the arc is transferred to it and the welding torch then operates in an arc transfer mode. Such Welding torches are sufficient for use when heating, Welding, cutting, melting, tempering etc. known.

It is with the aforementioned plasma arc welding torches also known, the plasma gas upstream of the gas space To give swirl movement, which serves cooling purposes on the one hand, on the other hand, has the purpose of bundling the ejected plasma jet to keep in line with the axis of the electrode. Such a swirl can result in a good quality plasma arc be generated. It also improves the cutting speed and thus the economy and efficiency of the work performed and is general in operation the welding torch. It is also known in welding torches with fixed nozzle and electrode arrangement gas with swirl To face inward on the end faces of the electrode to remove erosion deposits to remove or even from the nozzle element not to let it occur and thus increase its lifespan increase. Other efforts to control the Gas flow has the gas swirling around the out of the Outlet opening of the nozzle element including the plasma jet emerging, to prevent the plasma jet from moving sideways stabilize and around the twist strength and the speed of the plasma gas entering the gas space before the Reduce plasma jets in order to achieve a uniform Flow to achieve the plasma gas and the arc beam to keep the welding torch stable. Swirling the gas before entering the gas chamber between the electrode and the plasma jet outlet also included directing the swirl gas radially inward around the working tip of the electrode to stabilize the plasma jet against lateral wandering.

During the aforementioned efforts for directional control of the plasma jet and to create a protective jacket around it around their purpose, however, remains disadvantageous that the swirl of the gas between its point of generation and the Plasma jet outlet subsides, so that the desired bundling of the Beams into a shape in which he is practically only one straight Line does not follow between the nozzle element and a workpiece is fully achieved. In addition, the arrangements known to date have created in an effort, the desired one Control of the plasma jet including a protective gas jacket get a complicated structure and are therefore expensive in Manufacturing and maintenance. The slackening of the twist motion is to explain that the gas as soon as it leaves the passage or exits the passages which give the gas the swirl movement, to and through the gas space Inner surfaces of the nozzle element to the plasma jet outlet opening moves that are evenly shaped and therefore unsuitable, the maintain initial swirl motion. Also learns the swirling gas usually has a pressure drop when it comes out of the Passage or the passages in which the swirling exits is generated, with such a pressure loss to weaken of the swirl contributes to the swirl flow.

The object of the invention is the flow behavior of the gas relative to the electrode and nozzle element of a plasma torch to improve.

In a further embodiment of the invention, a nozzle element be created for a plasma torch with an arrangement which gives the plasma gas a twist when it goes to and through the outlet opening one between the electrode and the nozzle member arranged gas space flows.

In an advantageous development of the invention, a plasma arc welding torch is used with an improved nozzle and Electrode arrangement for controlling the plasma gas flow created, to achieve the best possible cooling and one plasma jet emerging as straight as possible and a good one Obtain plasma gas shielding for the beam.

A plasma torch with nozzle and Electrode elements created to generate a pilot arc are displaceable relative to each other and so in Can be brought into contact or separated from each other, whereby the burner has improved gas flow control, thereby a gas bias of the components both for their contacting as well as optimized for their separation.

In an expedient embodiment, the invention turns into a plasma welding torch indicated with a nozzle and electrode arrangement, for an improved flow characteristic of the plasma gas ensures and the high quality of the arc beam and thus the work performed as well as a special one high efficiency and low operating costs of the welding torch can be achieved.

The present invention provides an improved nozzle element and electrode assembly for a plasma arc welding torch created, in which the aforementioned and other disadvantages inherent in controlling gas flow be reduced to a minimum or completely overcome. In in this respect is in particular the head wall of the nozzle element with the outlet opening for the plasma jet with a Provide guide arrangement that ensures that the extent plasma gas entering the gas chamber radially along the head wall with swirl to the outlet opening, the gas up is swirled to the entrance of the plasma jet outlet in order to to press or radially constrain it into a beam that is particularly straight and has a high stability against has side deflection. The gas flow is swirled only in the direction of flow behind the working tip of the electrode, so that he has no erosive influence on them and thereby does not shorten the life of the electrode. Preferably gives the gas the twisting motion that the inside the head wall of the nozzle element with several, in the circumferential direction spaced, arcuate ribs is provided between them curved, approximately spiral from the outer edge of the gas chamber to Exhaust opening extending channels are formed which the plasma gas give the swirl movement where the plasma arc or beam is generated.

In a plasma arc welding torch, in which the electrode and the nozzle element relative to one another between one Contact position and a working position is movable, the plasma gas can reach the tip of the electrode, if the latter hits the ribs, the available force to push the electrode back out of contact with the Increase nozzle element. Similarly, in one embodiment, one of which is pressurized by means of a solenoid valve controlled piston arrangement is provided and actuated to bring the electrode into contact with the nozzle element the contact force between the working tip of the electrode and the nozzle element due to the smaller contact area between the electrode and the nozzle element with the same Gas pressure will increase. As a result, the gas pressure can also be reduced, which is required to have a good electrical Contact between the electrode and the nozzle element too create compared to the one that is then required if an electrode against a smooth inner surface of the nozzle element bumps.

In a further embodiment of the invention, the nozzle element is on a welding torch body together with a coaxial sleeve arrangement mounted, which forms an annular cooling cavity, through which a portion of the plasma gas can flow, and preferably a conical gas protection jacket around the out of the gas space forms in the interior of the nozzle element emerging plasma jet. The coaxial sleeve elements preferably clamp axially Flange arrangement on the outer edge of the nozzle element near one its ends and the flange and the corresponding end of the Nozzle element with one through the welding torch body associated with swirling gas, part of the gas flows outward and over the flange assembly while the remaining part of the gas inside the nozzle element and flows along the electrode to the gas space. The nozzle element points on its outer edge an axially extending recess in the flow direction behind the flange arrangement through which the over the flange assembly gas flowing radially outward and axially is deflected forward in front of the nozzle element and so one Shielding gas jacket around the plasma jet emerging from the gas space forms. The flange arrangement stands with the annular Cooling cavity communicates and provides, together with the recess downstream, for a simply constructed nozzle element, at which the flow of part of the plasma gas is controlled to to achieve cooling and a conical protective gas jacket train while the rest of the gas between that Nozzle element and the electrode is directed to the gas space to get there and generate a plasma jet. Preferably that occurs between the electrode and the nozzle element and the gas space to flow plasma gas from a swirl arrangement, the arranged in the flow direction of the gas in front of the nozzle element is. The structure of the nozzle element enables an external flow into the cooling space and along the outside of the nozzle element and thereby produces a preferably conical Gas shield regardless of the plasma gas in the gas space, the result its swirl movement is given immediately at the point which creates the plasma jet.

Fig. 1

die Bauteile eines erfindungsgemäßen Plasma-Lichtbogen-Schweißbrenners in einer perspektivischen, auseinandergezogenen Darstellung;

Fig. 2

den Schweißbrenner nach Fig. 1 im zusammengebauten Zustand im Schnitt;

Fig. 3

eine Draufsicht auf das Düsenelement des Schweißbrenners;

Fig. 4

das Düsenelement nach Fig. 3 in einer Seitenansicht und teilweise im Schnitt;

Fig. 5

eine die Abmessungen und geometrischen Ver hältnisse der Drallrippen und -kanäle zeigende Detailansicht des Düsenelements; und

Fig. 6

einen Querschnitt durch einen Abschnitt der Kopfwand des Düsenelementes entlang der Linie 6-6 in Fig. 5, die das Profil einer erfindungsgemäßen Wirbeirippe in perspektivischer Darstellung zeigt.

These and further features and advantages of the invention result from the following description and the drawing, in which a preferred embodiment of the invention is explained in more detail using an example. It shows:

Fig. 1

the components of a plasma arc welding torch according to the invention in a perspective, exploded view;

Fig. 2

the welding torch of Figure 1 in the assembled state in section.

Fig. 3

a plan view of the nozzle element of the welding torch;

Fig. 4

3 in a side view and partly in section;

Fig. 5

a detailed view of the dimensions and geometrical relationships of the swirl ribs and channels showing the nozzle element; and

Fig. 6

a cross section through a portion of the head wall of the nozzle element along the line 6-6 in Fig. 5, which shows the profile of a spine according to the invention in a perspective view.

1 and 2 show an arc plasma welding torch 10 with a body part 12 aligned coaxially to an axis A, that a coaxially arranged nozzle element, an electrode and has an arrangement for electrode displacement, the following will be described in detail. In the further description the information "below" and "above" are accordingly the vertical orientation of the welding torch 10 in FIG. 1 and 2 used.

As can be seen from FIG. 2, the body part 12 has a lower, provided with an internal thread 14 and an external thread 16 The End. At the lower end of the body part 12 is a swirl ring construction arranged, a sleeve 18 made of insulating material and has a mounting sleeve 20 and with one arranged on the sleeve 18 External thread 22 in the internal thread 16 on the body part. 12 is screwed in. The insulating sleeve 18 is on its inner wall with a plurality of radial passage openings 24 and with an O-ring seal 26 provided in an extending on the circumference of the sleeve Ring groove is added. The mounting sleeve 20 has at its lower end an end face 28 transverse to axis A. and has one that widens upward from the face Cone wall section 30 and one axially from the cone wall section 30 upward extending region with several V-shaped Ribs 32, which extend axially on the circumference of the mounting sleeve are arranged. At the top of the ribs 32 is by radial Jump inwards a paragraph (without reference number) formed, which abuts the lower end surface of the body part 12 and thus fixes the swirl ring construction on it.

At the lower end of the body part 12 is by means of a mounting sleeve or a shield sleeve 36, a nozzle element 34 is mounted. For this purpose, the shield sleeve 36 has an internal thread at its upper section 38, which cooperates with the external thread 14 on the body part 12. The nozzle element 34, which will be described in more detail below has an intermediate section with a mounting flange located between the upper and lower ends 40 on that between the end face 28 of the mounting sleeve 20 and one formed at the lower end of the end sleeve 36 by a flange 42 and shoulder extending radially into the sleeve 41 is clamped. As can best be seen in FIG. 2, the inside of the shielding sleeve 36 has a conical surface 44, which extends from the shoulder 41 to the internal thread 38 and that radially from the cone wall portion 30 and the ribs 32 the mounting sleeve 20 is spaced and thus a cavity 46 forms, the meaning of which will be explained below.

In the welding torch 10 there is also a coaxial with the axis A. Supported electrode 48 which is relative to the nozzle element 34 is displaceable. The electrode 48 has an outer cylindrical one Working tip 50 received in the nozzle member 34 and is at the bottom near her End face 52 an insert 54 made of hafnium, zirconium, tungsten or some other suitable material that is used together with the nozzle element when operating the welding torch generate a plasma arc, as is the case with plasma torches is known.

The electrode 48 is above the working tip 50 with a Provided gas swirl section, the helical swirl grooves 56th has and received in the sleeve 18 of the swirl ring construction is that the grooves 56 together with the sleeve wall are preferred form closed channels. The upper end of the electrode 48 is provided with a head 58. The between the twist grooves 56 and the sleeve 18 formed, helical channels have inlet gaps, which are below head 58 and close the passage openings 24 are arranged in the sleeve 18. The the lower outlet gaps of the channels are above the working tip 50 and are close to each other End faces of the nozzle element 34 and sleeve 18 are arranged.

The welding torch 10 also has a piston-cylinder arrangement , with the help of the electrode 48 relative to the welding torch body 12 and thus also axially displaceable to the nozzle element 34 is. This is at the upper end of the welding torch body 12 a cylinder element 60 with a head part 62 on the top End of the body 12 and provided with a sleeve part 64, the extends downward from the headboard 62 and with its lower one End the sleeve 18 of the swirl ring construction outside in Axial direction overlapped a bit. The head part 62 bumps with its lower end on a shoulder 66 in the welding torch body 12 and is at the top with a locking ring 68 in Welding torch body 12 held. The outer surface of the sleeve section 64 of the cylinder element 60 is with several axially extending Provide recesses 70 which are distributed over the circumference are spaced from each other. Also in the sleeve section a plurality of passage openings 73 are provided, the radially starting from some or all of the recesses 72 extend through the sleeve portion 64. In the head section 62 of the Cylinder element 60 are radially extending ventilation openings 74 arranged, which open into an annular channel through an opening 78 in the welding torch body 12 in connection with ambient air is. The ventilation openings are between two O-rings 80 arranged in associated, in the outer circumference of the head section 62 trained grooves sit and the head section against seal the inside surface of the torch body 12 if the cylinder element is mounted in this.

The piston-cylinder arrangement of the welding torch 10 also has a piston element 82 with a head 84, the one has annular sealing ring 86. The lower end 88 of the piston member 82 faces the head 58 of the electrode while it is at the top in Form a tube 90 protrudes from the burner. The piston 82 is received in the cylinder element 60 and axially in this reciprocable; for this purpose the head 84 of the piston is in the Received sleeve portion 64 of the cylinder member 60, wherein the lower piston end 88 abuts the upper end 58 of the electrode. The piston 82 is a compression spring 92 from the in Fig. 2 shown biased down. The piston 82 is in the position shown in Fig. 2 by the plasma gas moved, which is introduced under pressure through the inlet bore 94 becomes and axially along the recess 70 and then radially flows inwardly through the passage openings 24 in the sleeve 18 and so gets under the head 58 of the electrode. Part of the gas entering through inlet 94 flows through the transverse bores 72 and further through culverts opening into the tube 90 96 and then up through one formed by tube 90 Channel 98. The inlet of the gas through opening 94 is by means of controlled a solenoid valve, not shown, for example is triggered when the operator triggers the trigger actuated to start the welding torch. When moving of the piston 82 in the position shown in FIG. 2, the air which are in the starting position of the piston above its piston head 84 is located through the outlets 74, 76, 78 to the outside dissipated. When the operator releases the trigger, closes the solenoid valve so that the gas pressure at the inlet passage 94 drops and spring 92 piston 82 from that shown in FIG Position moved down, causing the electrode 48 after is moved below. The then below the cylinder head 84th Air is through the radial passage opening 96 and derived the pipe channel 98, whereby the Piston is cooled. As the piston 82 moves down, is air through the holes 74, 76, 78 in the space above of the piston head 84 sucked. When operating the welding torch plasma gas flows continuously through the welding torch body and past the nozzle and electrode elements, thereby it is not just the exit of a plasma arc beam enables, but also for cooling the various components worries. The plasma gas used as cooling and working gas is therefore in the welding torch body 12 through the inlet 94th supplied, which is designed as a radial opening in the welding torch body and is near the top ends of the recesses 70 is located in the sleeve section 64 of the cylinder element 60.

As can be seen in particular from FIGS. 3 to 6, the nozzle element 34 approximately tubular and forms a coaxial to the axis A aligned cylinder bore 100 which at the upper end 101 of the Nozzle element 34 is open and so the working tip 50 of the electrode 48 can accommodate. The lower end of the cylinder bore is bounded by an end wall 102 arranged transversely to the axis A, in which a plasma arc outlet opening 104 is also coaxial to axis A is provided. The mounting flange 40 has one upper and a lower flange side 106 and 108 and one Outside edge and is on with the circumference at regular intervals distributed, V-shaped recesses 110 provided are open to the outside edge. Below the lower one Flange side 108 of flange 40 has nozzle element 34 first cylindrical section 112, an adjoining flared portion 114 and a second cylindrical section 116, which has a larger diameter has as the first cylindrical portion 112, so that the conical section from the smaller diameter of the first Cylinder section to the larger diameter of the second cylinder section expanded accordingly.

Each of the recesses 110 on the flange 40 has one opposite first cylinder section 112 radially further outward inner surface 118, i.e. that of the inner surfaces of the recesses 110 defined diameter is larger than the diameter of the first Cylinder section. The upper end of the nozzle element 34 is in the Area between the upper flange side 106 and the upper end 101 of the nozzle element is provided with a plurality of axial grooves 120. The Number of axial grooves 120 corresponds to the number of recesses 110, wherein each groove 120 is assigned a recess 110 and Groove and associated recess are arranged so that each other the groove base 122 of each groove is coplanar with the radially inner one Surface 118 of the associated recess 110 is.

The cylinder space 100 of the nozzle element 34 is on its circumference through which from the upper end 101 of the nozzle element to End wall 102 extending cylinder surface 124 delimited. The End wall 102 has an inner top surface 126 that is approximately orthogonal runs to the axis A and wrongly shown embodiment between peripheral surface 124 and outlet opening 104 slightly is inclined. The peripheral surface 124 goes under one Radius in the top 126 of the end wall 102. On the Top side 126 of end wall 102 is a plurality of swirl ribs 130 provided at an even distance around axis A. are arranged and approximately spiral from the peripheral surface 124 extend radially inward towards the outlet opening 104. In the illustrated embodiment, there are six of them Swirl ribs provided. As can be seen particularly clearly from FIG. 5 results, each of these ribs has an outer and an inner curved Side wall 132 and 134, which are approximately parallel and in Are spaced from each other, the radial thickness of a Rib sets. The arrangement is such that the side walls 132 and 134 a radius of curvature R1 or R2 by one have reference point 136 to the side of axis A. The reference point 136 lies on a first reference line 137, which is aligned with a second reference line 139, which is orthogonal to this intersects at a point that is a bit opposite to axis A. is radially offset. At the radially inner or outer end 138 or 140 close the ribs 130 in an arc shape with arcs of curvature R3 or R4, which are struck about the axis A. The reference lines 137, 139 and reference points 136 as centers of curvature for the radii R1 and R2 of adjacent ribs evenly distributed and have an angular distance that is 360 °, divided by the number of ribs. Accordingly would be the reference lines (not shown) and the reference point for the dot-dash line 130 shown in FIG. 5 me 60 ° clockwise from reference line 137 and that Reference point 136 is offset, which is shown in Fig. 5 for the solid shown (left) rib are shown.

As can further be seen from FIG. 5, the radius of curvature corresponds the outer ends 140 of the ribs the inner radius of the cylinder wall 124 of the cylinder bore 100. FIG. 6 shows that the ribs 130 have an upper side, the radially outer, a bit above the top 126 of the end wall 102 End has an arc section 144 that has a harmonic Forms transition to the inner wall 124 of the cylinder opening 100. Starting from its radially outer end, the Thickness of the ribs in the axial direction to the radially inner end back, which in turn has a second arc section 146, which has a practically stepless transition to the top 126 the end wall ensures. The top 142 is preferred between their radially inner and radially outer ends convexly curved, which creates a particularly good contact between Electrode and top of the fins when starting the welding torch is achieved.

3 to 6 that two each in the circumferential direction side-by-side twist ribs between them form a gas flow channel 148, each of which is an inlet end on the inner wall 124 of the cylinder opening 100 and a Exit end has that between the radially inner ends of the Rib side walls 132 and 134 of two adjacent ribs lies. As can be seen in particular from FIGS. 3 and 5 the circumferential distance between the side walls of two adjacent ribs larger at the entry end of each channel than at the exit end. That in each channel 148 at the input end entering gas flows along a curved, in Flow direction tapered path to the outlet end of the Channel. The channels are designed so that the gas on their Eject outlet openings in directions that are approximately tangent to Outlet opening 104 run. The trained between the ribs Channels ensure through their special design that the gas not only swirls when entering the outlet opening 104, but is also constricted radially, making a special straight (linear) plasma jet emerges from the welding torch.

Exemplary and only to clarify what is shown and described embodiment is the inner diameter the cylinder opening 100 of the nozzle element 34 is approximately 8.636 mm and the inside top 126 of the end wall is about 15 ° inclined to a plane orthogonal to axis A. Of the The diameter of the outlet opening 104 is in the exemplary embodiment shown about 1.07 mm, while the radii of curvature R1 and R2 at 3.175 and 2.54 mm, respectively, and the radii R3 and R4 at 1.78 or 4.32 mm. The reference point 136 is at a distance from Intersection of lines 137 and 139 of 1.93 mm, the Intersection of these two lines in turn by 0.1016 mm from the Axis A is spaced. The radius of curvature of the arcuate Sections 128, 144 and 146 between the inner and end faces, respectively 124, 126 of the nozzle and the outer and inner ends of the ribs 130 is 0.635 mm. Each rib is with a radius of 3.175 mm convexly curved on its upper side around a center of curvature, which is 5.26 mm from the axis to the side and 16.33 mm from the top 106 of the flange is removed.

2 the electrode is shown in its working position, in which the working tip 50 is at a distance above the end wall 102 of the nozzle element 34 is located. electrode and nozzle element are arranged in a manner known per se, that they are connected to each other via a power source, so that a pilot arc was struck between these two components becomes and burns when the electrode is shown in Fig. 2 Position down in contact with the nozzle element 34 or its Swirl ribs 130 brought and then back into their in Fig. 2 shown position is withdrawn. With such a The starting process is between the lower end face 52 of the working tip 50 of the electrode and the axially inner top 126 of the end wall 102 of the nozzle element 34 is a plasma gas space 150 formed, the one running around its outer edge, has annular inlet 152 which passes through the annular gap between the inner wall 124 of the nozzle element and the peripheral surface the working tip 50 of the electrode 48 is fixed. Before a pilot arc is generated, the end face 52 of the Working tip 50 of the electrode 48 due to the compression spring 92 applied force on the ribs 130. To start the burner a plasma gas is then passed through inlet 94 into the welding torch body 12 initiated and flows through the annular Gap between the body 12 and the cylinder sleeve 64 and axially along the recesses 70 through the passage openings 24 in the sleeve 18 of the swirl ring construction. After flowing through the Gas through the radial passage openings 24 acts on the gas pressure onto the underside of the head 58 of the electrode 48 and lifts it so against the bias of the spring 29 upwards in the in Fig. 2nd shown location. The gas continues to flow down along the top of the electrode and further through the swirl channels 56 to the lower end of the sleeve 18, where part of the gas with swirl into the annular passage between the inner wall 124 of the nozzle element and outside of the working tip 50 of the electrode flows and from there via an edge entry 152 into the gas space 50 arrives. The plasma gas then continues to flow approximately in a spiral inwards in the formed between adjacent ribs 130 Channels, from which it is approximately tangential to the outlet ends Edge of the outlet opening 104 exits. The gas leaves the opening 104 thereby with a twist. When the electrode is out of contact device with the nozzle element and - as described - a pilot arc burns between the electrode and the nozzle element, escapes the gas chamber 150 a plasma jet P with the in the channels 148th generated swirl. As long as plasma gas through the gas space 150 flows, a pressure is exerted on the end face 52 of the electrode, a lower pressure is required to achieve the To keep electrode 48 in its operating position.

4 and 6, the gas flows at his Entry 152 into the gas space 150 and radially through it to the outlet opening 104 and in its passage through the between the ribs 130 formed channels 148 and through the curved Sections 144 and 128 near entrance 152 due to the smooth transitions and radii practically without turbulence and there will be a particularly good flow transition between the axial-helical course along the working tip 50 the electrode 48 and the spiral, radially inward Flow in channels 148 along ribs 130 in Direction towards the outlet opening 104 reached. The invention The design of the transition flow also has a special one Advantage that the direction of the swirl flow around the Working tip 52 of the electrode around in the flow direction the chamber 150 of the direction of flow of the gas through the channels 148 between the ribs, which also leads to that a transition flow with very little or no Turbulence is developing. After creating the pilot arc the torch is operated in pilot arc mode, in which the Arc has not yet jumped onto a workpiece. Of the Torch can then be in the vicinity of a workpiece for arcing are moved, the torch then in the arc transmission mode is working.

The special design of the nozzle element 34 has during operation the welding torch also has special advantages in direction control of the partial flow of the plasma gas provided for cooling. As can be seen from FIGS. 2 to 4, flows a part of the inflow through the passages 24 and from there through the helical channels 56 to their outlet ends guided plasma gas above the nozzle element 34 through the Grooves 120 on the outside thereof and further through the Recesses 110 in the mounting flange 40 of the nozzle element. Another part of the plasma gas flowing through the grooves 120 passes radially outward from the recesses 110 into the annular gap between the surfaces 30 and 44 of the mounting ring or the shield sleeve 36 and the cooling fins 32 into the cavity 46, causing the components of the welding torch in this area be chilled well. Yet another sub-stream of through the Grooves of plasma gas flow through the recesses 110 in flange 40 and is radially inward against the first cylinder section the nozzle 34 steered and from there to the conical section 114. As the shoulder 41 on the shield sleeve 36 a part of the recesses 110 near the bottom 108 of the Flange 40 overlaps radially and the opening of the nozzle element with a conical wall section 43 from the shoulder 41 tapering down towards the outlet, this becomes axial flowing along the bottoms 118 of the recesses 110 Gas radially inward toward cylinder portion 112 of the Nozzle deflected. When continuing to flow along this nozzle area the gas reaches the conical section 114 and is thereby deflected radially outwards and thus forms an approximately conical Protective jacket around the plasma jet P.

The invention is not based on that shown and described Embodiment limited, but there are many Changes and additions without going beyond the scope of the invention leave. For example, the invention is also possible to be used in such a welding torch where the nozzle and Electrode not slidably arranged to each other, but are stationary, in which case the burner is not moved the electrode in the nozzle element is started, but for this a suitable electrical (radio frequency) circuit use finds. It is possible to outline the swirl ribs on the inside to design the end wall of the nozzle element somewhat differently and for example more or less than six ribs to use. The swirl of the gas can also be at its own Flow generated over the end face of the nozzle element be without the previously taken in the direction of flow of the gas Arrangement provided with the helical channels becomes. This swirl of the gas upstream can also be generated differently be, for example, that the gas is not through one radial, but one or more tangentially arranged Inlet openings 94 is supplied.

Claims (38)

Plasma torch with a nozzle element (34) having an outlet opening (104) and an electrode (48) at least partially accommodated therein, one end face (52) of which is directed towards the end face (102) of the nozzle element (34) having the outlet opening (104), wherein a gas space (150) is formed between the nozzle element (34) and the electrode (48), the plasma gas can be supplied via a radially outer inlet (152), and with a device for generating an arc between the nozzle element (34) and the Electrode (48) for generating a plasma jet (P) when the plasma gas emerges from the outlet opening (104), characterized in that on the end face (102) of the nozzle element (34) and / or on the end face (52) of the electrode (48 ) Guide means (130, 148) for guiding the plasma gas from the radially outer inlet (152) to the inner outlet opening (104) are provided. Plasma torch according to Claim 1, characterized in that the guide means have a plurality of ribs (130) which are arranged on the end face (102) of the nozzle element (34) and are spaced apart from one another in the circumferential direction around the outlet opening (104). Plasma torch according to claim 1 or 2, characterized in that the guide means form a plurality of gas guide channels (148) which are arranged on the end face (102) of the nozzle element (34) and are spaced apart from one another in the circumferential direction around the outlet opening (104). Plasma torch according to one of claims 1 to 3, characterized in that the channels (148) have a radially outer (140) and a radially inner end (138), the dimensions of the channels being greater in the circumferential direction at the outer end (140) than at inner end (138). Plasma torch according to one of claims 1 to 4, characterized in that the channels (148) and / or the ribs (130) run in an arc shape between their radially outer ends (140; 144) and their radially inner ends (138, 146). Plasma torch according to one of claims 1 to 5, characterized in that the ribs (130) laterally delimit the gas guide channels (148) running between them. Plasma torch according to claim 5, characterized in that the ribs (130) have an outer and an inner end and are arranged uniformly distributed in the circumferential direction. Plasma torch according to one of claims 1 to 7, characterized in that the distance in the circumferential direction of two adjacent ribs (130) is smaller at their inner end (146) than at their outer end (144). Plasma torch according to one of claims 1 to 8, characterized in that the radially outer (140) and inner ends (138) of the ribs (130) are bent with a radius of curvature (R3, R4) around the axis (A) of the outlet opening (104) are. Plasma torch according to claim 9, characterized in that the radius of curvature of the outer fin ends (140) corresponds to the radius of the peripheral wall which delimits the gas space on the peripheral side. Plasma torch according to one of claims 1 to 10, characterized in that the inner ends (138) keep a radial distance from the peripheral edge of the outlet opening (104). Plasma torch according to one of claims 1 to 10, characterized in that the gas chamber (150) to the axis (A), has coaxially of the outlet port (104) includes a peripheral wall (124) into which the ribs merge with their radially outer ends having a radius, the parts of the peripheral wall remaining between two adjacent ribs (130) form the axially projecting, outer boundary of the channels and pass into the respective channel bottom with a radius. Plasma torch according to one of claims 1 to 12, characterized in that the side walls (132, 134) of the ribs are curved around a reference axis which runs parallel to the axis (A) of the outlet opening (104) and is laterally offset from this. Plasma torch according to one of claims 1 to 13, characterized in that the ribs (130) taper from the radially outer to the radially inner fin end with their upper sides pointing towards the end face (52) of the electrode (48). Plasma torch with a tubular nozzle element (34) symmetrical about an axis (A) with an end face (102) arranged transversely to the axis (A), with an electrode (48) arranged coaxially in the nozzle element (34), which electrode is located near the end face (102) arranged end face (52), the end face (52) and the end face (102) delimiting a plasma gas space (150) with an outlet opening (104) coaxial to the axis (A) through the end wall (102) and that Nozzle element (34) and the electrode (48) form an approximately annular inlet (152) for the gas space (150) around a head tip (50) of the electrode (48), with means for supplying plasma gas through the inlet (152) into the gas space (150) with a flow direction essentially radially from the outside inwards from the inlet and means for generating an arc between the nozzle member (34) and the electrode (48) to flow a plasma jet through the outlet opening (104),
characterized in that the end face (102) of the nozzle element (34) has a plurality of channels (148) and / or ribs (130) on its upper side facing the end face (52) of the electrode (48), whereby the plasma gas inside the gas chamber ( 150) from the inlet (152) to the outlet opening (104). Plasma torch according to claim 15, characterized in that the channels (148) for the gas flow have means for concentrating the gas flowing from the inlet (152) to the outlet opening (104) in the circumferential direction and / or that each channel (148) has an outlet end for guiding the Has gas approximately tangential to the outlet opening (104). Plasma torch according to claim 15 or 16, characterized in that each channel (148) guides the gas flow along a curved path from the inlet (152) to the outlet opening (104), this path preferably narrowing progressively. Plasma torch according to one of claims 15 to 17, characterized in that the top of the end face (102) has an outer edge region coaxial with the inlet (152) and from which a plurality of ribs extend radially inwards, the ribs formed between adjacent ribs (130) Spaces form the gas flow channels (148). Plasma torch according to one of claims 1 to 18, characterized in that each of the ribs (130) has an outer and an inner end, circumferentially opposite side walls (132, 134) and between them an end face (52) of the electrode (48) has facing top (142), which slopes approximately wedge-shaped from the outer to the inner end to the end face (102) of the nozzle element (34). Plasma torch according to one of claims 1 to 19, characterized in that each channel (148) has an approximately radially extending bottom surface and an approximately axially extending outer end surface between opposite side walls of two adjacent ribs (130), the bottom surface and the outer end surface merge into an arc. Plasma torch according to one of claims 1 to 20, characterized in that the bottom surface of each channel (148) slopes from the radially outer to the inner end of the ribs (130) delimiting the respective channel. Plasma torch according to one of claims 1 to 21, characterized in that the gas space (150) has an edge wall (124), the outer ends (140) of the ribs (130) merging into the edge wall (124) and between the adjacent ribs (130) located portions of the edge wall (124) form the axially extending outer end sides of the channels and wherein first curved surfaces connect the bottom surfaces to the radial outer end sides and second curved surfaces connect the rib tops (142) to the edge wall (124). Plasma torch according to one of Claims 1 to 22, characterized in that the upper sides (142) of the ribs (130) have a section between the radially outer and inner ends which is convexly curved with respect to the end face (52) of the electrode (48). Plasma torch according to one of claims 1 to 23, characterized in that the outlet opening (104) forms a peripheral edge and the outlet ends of the channels (148) are arranged such that the escaping gas flows along an annular path relative to the edge. Plasma torch according to one of claims 1 to 24, characterized in that the ribs on their upper side (142) taper axially from the outer to the inner rib end in the direction of the end face (102). Plasma torch with a welding torch body (12), with a tubular nozzle element (34), preferably symmetrical to an axis (A), arranged on the body, with an inner wall (124) extending in the direction of the axis, axially opposite ends and with an end wall (102) at one of the ends, with an electrode (48) which is supported in the welding torch body (12) and has a working tip (50) and is aligned coaxially to the nozzle element (34), the working tip (50) of the electrode (48) having an end face (52) which is close to the End wall (102) arranged and bounded with this a plasma gas space (150) which is provided with an axially extending through the end wall (102) outlet opening (104), wherein the working tip (50) of the electrode (48) has a peripheral surface which extends from the end face (52) along the inner wall (124) of the nozzle element (34) and forms a first annular gas passage opening into the gas space (150), the inlet of which is located at the other, opposite end of the nozzle element ( 34), the nozzle element (34) having an outer surface between its two ends, which has a first cylindrical (112), a conical (114) and a second cylindrical surface section (11 6) which are coaxially aligned with one another and axially adjacent and follow one another towards the nozzle end, the diameter of the first cylindrical surface section (112) being smaller than that of the second surface section (116) and the conical surface section (114) extending from the first to the second surface section extended, means for supplying plasma gas both into the entry end of the first gas passage and along the outside of the nozzle element (34) for flow both into the gas space (150) and axially along the first cylindrical surface portion (112) to the conical portion (114 ), and means for generating an arc between the nozzle member (34) and the electrode (48) to flow a plasma jet through the outlet opening (104), the gas flowing along the first cylindrical surface portion being radial by means of the conical surface portion (114) is directed outwards and axially towards one end of the nozzle element (34) and forms an approximately conical protective gas jacket for the plasma jet. Plasma torch according to claim 26, characterized in that the nozzle element (34) has on its outer surface an outwardly projecting mounting flange (40) which has an upper and a lower flange side (106, 108) and means which form a second gas passage having an axially extending portion over the mounting flange (40), the second gas passage extending axially along the outer surface of the nozzle member (34) and having an inlet at one end of the nozzle member (34) and an outlet on the mounting flange (40), and wherein at least a portion of the gas directed to the outer surface of the nozzle member is directed into the inlet of the second gas passage. A plasma torch according to claim 27, characterized by means having nozzle mounting means abutting the upper flange side (106) of the mounting flange for deflecting the gas flowing through the outlet of the second gas passage radially inward towards the first cylindrical surface portion (112). Plasma torch according to one of claims 26 to 28, characterized by nozzle mounting means arranged on the welding torch body (12) with a first (20) and a second sleeve element (36) which clamp the mounting flange means between them, the second sleeve (64) being the first sleeve (20) surrounds such that a cavity (46) is formed between the sleeves and wherein the second gas passage in the mounting flange has passages that are in flow communication with the cavity and through which a portion of the gas flowing through the second gas passage into the cavity can flow. Plasma torch according to claim 29, characterized in that the first sleeve (20) has an outer edge portion which forms a plurality of axially extending and circumferentially spaced cooling fins (32) in the cavity. Plasma torch according to one of claims 1 to 30, characterized in that the electrode (48) at a distance from the working tip (50) has an area with means for generating an approximately helical swirl flow of the gas around the electrode axis and axially towards the entry end of the first Has gas passage and / or the second gas passage. Plasma torch according to one of claims 26 to 31, characterized in that the end wall (102) of the nozzle element (34) has means for imparting a swirl movement to the gas flowing from the first annular gas passage (152) to the outlet opening (104). Plasma torch according to one of claims 27 to 32, characterized in that the mounting flange (40) is located on the outer circumference of the nozzle element (34) and has an outer edge, the second gas passage on the flange having a plurality of recesses (110) which are open and spaced apart from one another. having. Plasma torch according to one of claims 27 to 33, characterized in that the radially inner ends of the recesses (110) are located further outside than the first cylindrical section (112). Plasma torch according to one of claims 27 to 34, characterized in that the means for forming a second gas passage have a plurality of grooves (120) in the outer surface of the nozzle element (34) which extend axially from the lower flange side (108) of the mounting flange (40) to extend to the upper end of the nozzle element (34). Plasma torch according to one of claims 27 to 35, characterized in that as many grooves (120) as recesses (110) are provided, the grooves (120) having a groove base (122) which is steplessly in the bottom surface (118) of the associated Recess (110) merges. A plasma torch as claimed in any one of claims 27 to 36, characterized by a gas bypass arrangement on the inside of the second sleeve member which extends axially from top to bottom towards the nozzle member (34) and radially inward to radially flow the gas through the outlet end of the second gas passage to steer inwardly toward the first cylindrical surface portion (112). Plasma torch according to one of claims 27 to 37, characterized in that the end wall (102) of the nozzle element (34) has means for imparting a swirl movement to the gas flowing through the annular first gas passage to the outlet opening (104).

Images