Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/26—Plasma torches
  • H05H1/32—Plasma torches using an arc
  • H05H1/34—Details, e.g. electrodes, nozzles
  • H05H1/341—Arrangements for providing coaxial protecting fluids
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/26—Plasma torches
  • H05H1/28—Cooling arrangements
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/26—Plasma torches
  • H05H1/32—Plasma torches using an arc
  • H05H1/34—Details, e.g. electrodes, nozzles
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/26—Plasma torches
  • H05H1/32—Plasma torches using an arc
  • H05H1/34—Details, e.g. electrodes, nozzles
  • H05H1/3457—Nozzle protection devices

Definitions

• the invention relates to a plasma torch, in particular a plasma cutting torch.
• Plasma is a thermally highly heated electrically conductive gas, which consists of positive and negative ions, electrons and excited and neutral atoms and molecules.
• the plasma gas used is a variety of gases, for example the monatomic argon and / or the diatomic gases hydrogen, nitrogen, oxygen or air. These gases ionize and dissociate through the energy of an arc.
• the narrowed by a nozzle arc is then referred to as plasma jet.
• the plasma jet can be greatly influenced in its parameters by the design of the nozzle and electrode. These parameters of the plasma jet are, for example, the beam diameter, the temperature, the energy density and the flow velocity of the gas.
• the plasma In plasma cutting, the plasma is usually constricted by means of a nozzle, which may be gas or water cooled. As a result, energy densities up to 2x10 6 W / cm 2 can be achieved. Temperatures of up to 30,000 ° C occur in the plasma jet, which, in combination with the high flow velocity of the gas, result in very
• Plasma torches usually consist of a plasma torch head and a plasma torch shaft. In the plasma burner head, an electrode and a nozzle are attached. Between them flows the plasma gas, which exits through the nozzle bore. Most often, the plasma gas is passed through a gas guide that is mounted between the electrode and the nozzle and can be rotated.
• Modern plasma torches also have a secondary fluid supply, either a gas or a liquid.
• the nozzle is then surrounded by a nozzle cap.
• the nozzle is fixed in particular in the case of liquid-cooled plasma torches by a nozzle cap, as described, for example, in DE 10 2004 049 445 A1.
• Between the nozzle cap and the nozzle then flows the cooling medium.
• the secondary medium then flows between the nozzle or the nozzle cap and the nozzle protection cap and emerges from the bore of the nozzle protection cap. It influences the plasma jet formed by the arc and the plasma gas. It can be set in rotation by a gas guide which is arranged between nozzle or nozzle cap and nozzle cap.
• the nozzle protection cap protects the nozzle and the nozzle cap from the heat or the ejected molten metal of the workpiece, in particular when piercing the plasma jet into the material of the workpiece to be cut. In addition, it creates a defined atmosphere around the plasma jet during cutting.
• nitrogen is often used as a secondary gas to prevent alloyed steels plasma cutting from contacting and oxidizing the oxygen in the ambient air with the hot cut edges.
• nitrogen causes the surface tension of the surface Melt reduced and thus better driven out of the kerf. There are beard-free cuts.
• valves and the plasma torch This is particularly critical if it is necessary to switch between different secondary media, for example an oxidizing (oxygen, air) and a non-oxidizing gas or gas mixture. Also critical is switching between a liquid (eg water, emulsion, oil,
• Aerosol and a gas
• a common feeder eg a hose
• the gas must first rinse all the remaining liquid in it. This can take several 100 ms.
• valves on plasma torch shaft is unfavorable for mounting in the guide system, especially for swivel units, this is disturbing.
• plasma cutting torch is guided by at least one supply at least one secondary medium through a housing of the plasma torch up to a Düsenschutzkappenö réelle and / or other openings that are present in a nozzle cap.
• at least one valve for opening and closing the supply is provided directly inside the housing of the plasma torch.
• the feed can be divided into at least two parallel feeds through which secondary medium flows in the direction of the nozzle protective cap opening and / or further openings and within the housing then at least two valves for opening and closing the respective split feed are present, which can each be activated individually , so that there is the possibility that one of the valves alone can open the supply of the secondary medium, secondary medium can flow simultaneously through both split feeders or a switchover can take place from one to the other split supply line.
• At least two feeds for two different secondary media can be guided through the housing of the plasma torch up to a nozzle protection cap opening and / or further openings which are present in the nozzle protection cap and at least one each in the feeds for a respective secondary medium within the housing Valve for opening and closing the respective feeder is present.
• the feeds should be designed so that the merging of the split feeders for a secondary medium or the merging of the feeds for different secondary media within the housing of the plasma torch, within the plasma head, in a space formed with the nozzle or nozzle cap and the nozzle cap, the supply flow of the secondary media streams from the split feeds and / or before, during or after passing through a gas guide of the plasma torch takes place. Accordingly, the confluence should occur within the housing, or plasma head.
• At least two ports or two sets of ports carrying the respective secondary media (s) should be present on the gas guide. With these openings, a targeted influence on the emerging from the openings secondary media can be achieved. These openings can be different sized and geometrically designed free
• Openings of different groups can be arranged radially offset from each other. The number of openings in the individual groups can be chosen differently.
• the arranged within the housing valves can be operated electrically, pneumatically or hydraulically and particularly preferably be designed as an axial valve.
• the valves arranged in the housing should have a maximum outside diameter or a maximum mean surface diagonal of 15 mm not more than 11 mm and / or a maximum length of 50 mm, preferably not more than 40 mm, more preferably not more than 30 mm and / or the maximum outer diameter of the housing should be 52 mm and / or the maximum outer diameter of the valves should be a maximum of J4, preferably a maximum Have 1/5 of the outer diameter or a maximum average surface diagonal of the housing and / or require a maximum electrical power consumption of 10 W, preferably 3 W, particularly preferably 2 W for their operation.
• the respective secondary medium or the plasma gas should flow through the winding of a coil (S) in order to achieve a cooling effect.
• it can be designed as a quick-change burner with a plasma burner shaft that can be separated from a plasma burner head. This can be achieved quickly and easily to different machining tasks.
• the nozzle guard should have at least one opening through which at least a portion of one of the secondary media flows, in addition to the nozzle guard opening or a retainer of the nozzle guard.
• one secondary medium in each case can exit through one or more selected openings in the direction of the workpiece surface.
• gaseous and / or liquid secondary media can be used gaseous and / or liquid secondary media.
• gases for example selected from oxygen, nitrogen and a noble gas
• liquids for example selected from water, an emulsion, oil and an aerosol or a gaseous and a liquid secondary medium.
• two secondary medium mixtures which are each formed with the same gases and / or liquids and thereby differ only the proportions of the secondary media forming the respective mixture. This can be, for example, a different proportion of oxygen contained in the secondary media mixture.
• the valve (s) disposed in a secondary fluid supply should be opened when at least a portion of the electrical cutting current flows through the workpiece, such that secondary medium from the plasma torch flows through the workpiece Can flow towards the workpiece surface.
• the valve (s) should be kept closed. This can be achieved with a controller, which is preferably connected to a database.
• a liquid or a liquid-gas mixture may be used as a secondary medium and a gas or gas mixture may be used as a secondary medium for cutting.
• valve (s) disposed in a secondary fluid supply should be opened at the earliest at the time such that secondary fluid flows from the nozzle cap bore at which the workpiece is at least about 1 when piercing a workpiece / 3, better half and best of all has been completely punctured.
• At least one valve which is arranged in a feed for secondary medium, should be able to be switched off during the start of cutting, between two cutting sections, when passing over a kerf F or at the cutting end. There is the possibility of switching two valves, which are arranged in two different feeds for secondary medium, during or during these processing tasks. That that a previously open valve closed and a hitherto closed valve can be opened.
• the parameters of the secondary medium (as described above) and to change at least one other parameter of the plasma cutting process.
• This can be, for example, an adaptation of the electrical parameters, an adjustment of the feed rate, the volume flow, the distance of the plasma torch to the workpiece surface and / or the composition of the plasma gas.
• all parameters can be stored in a database and used so that an automatic operation with a control of the plasma torch is possible.
• the parameters for the respective machining of a workpiece can also be present in the database and used.
• FIG. 1 shows in schematic form a sectional view through an example of a plasma torch according to the invention with a secondary medium supply with a valve and a plasma gas supply;
• FIG. 2 shows in schematic form a sectional view through an example of a plasma torch according to the invention with a secondary medium supply with two valves and a plasma gas supply;
• FIG. 4 is a schematic sectional view through a further example of a plasma torch according to the invention with a secondary medium feed with two valves and a plasma gas feed;
• Figure 5a u. b a guide for secondary media; in schematic form a sectional view through an example of a plasma torch according to the invention with two Sekundärmediumzu exiten with two valves and a plasma gas supply; in schematic form a sectional view through a further example of a plasma torch according to the invention with two secondary media supplies with two valves and a plasma gas supply; in schematic form a sectional view through another example of a plasma torch according to the invention with two Sekundärmediumzu exiten with two valves and a plasma gas supply; in schematic form a sectional view through an example of a plasma torch according to the invention with two Sekundärmediumzu exiten with two valves and a plasma gas supply with a valve and a vent valve; in schematic form a sectional view through an example of a plasma torch according to the invention with two Sekundärmediumzu exiten with two valves and two plasma gas supplies with two valves and a vent valve;
• Figure 11 is a sectional view of a usable in the invention
• Figure 13 shows another possibility for the arrangement of valves within the housing of a plasma torch.
• Figure 14 shows another possibility for the arrangement of valves within the housing of a plasma torch.
• Figure 15a u. b a sectional contour with large and small sections (contours)
• Figure 16a u. b is a sectional contour with vertical and chamfer cut
• FIG. 1 shows a plasma torch 1 with a plasma burner head 2 with a nozzle 21, an electrode 22, a nozzle protection cap 25, a supply 34 for a plasma gas PG1, a secondary medium feed SGI 61 and a plasma burner shaft 3 having a housing 30.
• the plasma torch shaft 3 may be integrally formed and formed only with a correspondingly configured housing 30, where all the necessary components can be present and formed.
• the feed 61 may be outside the housing 30 a gas hose, which is connected to a supply of secondary medium SGI with a coupling unit 5.
• the gas hose is followed by another part of the supply 61 and the valve 63, which are arranged inside the housing 30.
• the feeder 34 may be outside the housing 30 a gas hose, which is connected for a supply of plasma gas PGl with a coupling unit 5.
• a solenoid valve 51 for opening and closing the feeder 34 is arranged.
• the gas hose is followed by a further part of the feed 34, which is formed inside the housing 30.
• the electrode 22 and the nozzle 21 are spaced apart by the gas guide 23 so that a space 24 is formed within the nozzle 21.
• the feed 34 of the plasma gas PG1 is connected to the space 24. the.
• the nozzle 21 has a nozzle bore 210 which, depending on the electrical cutting current, may vary in diameter from 0.5 mm for 20 A to 7 mm for 800 A.
• the gas guide 23 also has openings or bores (not shown) through which the plasma gas PG1 flows. These can also be designed in different size or diameter and even number.
• the nozzle 21 and the nozzle guard 25 are spaced apart so that the spaces 26 and 28 are formed within the nozzle guard 25.
• the space 26 is located in the flow direction of the secondary medium SGI in front of the guide 27, the space 28 is located between the guide 27 and the Düsenschutzkappenö réelle 250.
• the flow of the secondary medium SGI for example, a gas, gas mixture, a Liquid or a gas-liquid mixture are symmetrized and / or rotated.
• the nozzle 21 may also be replaced by a nozzle cap or the like. be fixed (not shown). Then, the nozzle cap and the nozzle cap form the spaces 26 and 28.
• the secondary gas SGI is thus passed via the supply 61 and arranged in the plasma torch valve 63 into the space 26, symmetrized by the guide 27 and set in rotation.
• the secondary gas SGI then flows into the space 28 then exits the nozzle guard opening 250.
• one or more further holes 250a are located, through which the secondary medium SGI flows.
• the valve 63 is designed as an axial valve in a small design. For example, it has an outer diameter D of 11 mm and a length L of 40 mm. It requires a low electrical power for operation, here for example about 2 W to reduce the heating in the housing 30.
• the plasma gas PG1 flows through the open valve 51 and the supply 34 into the housing 30 and from there into the space 24 between the electrode 22 and the nozzle 21 and ultimately flows through the nozzle bore 210 and the Düsenschutzkappenöff - 250 out.
• the valve 51 is closed again and the supply 34 of the plasma gas PG1 is drained.
• the secondary medium in this example a gas (secondary gas SGI), can be switched through the valve 63 at the same time as the valve 51 of the plasma gas PG1. Due to the inventive arrangement of the valve 63 in the plasma burner shaft 3 and close to the plasma burner head 2, the secondary medium SGI can be switched on and off at other times.
• a gas secondary gas SGI
• the pilot arc with low electric current for example 10 A to 30 A, which burns between the electrode 22 and the nozzle 21, is ignited.
• the plasma jet 6 generated by the pilot arc touches the workpiece W to be cut, the arc is transferred from the nozzle 21 to the workpiece W.
• the control of the plasma cutting system detects this sensory and increases the electrical current to the required value, depending on the workpiece thickness in the processing area to 30
• the secondary medium SGI is not needed yet. It even disturbs and shortens the plasma jet 6 emerging from the nozzle 21, since it flows sideways. Therefore, the plasma torch 1 must be positioned closer to the workpiece W with its nozzle guard opening 250 and / or openings 250a. This in turn leads to jeopardy of the nozzle cap 25 and the nozzle 21 by hot high-pressure molten material. Remedy here creates the connection of the secondary medium SGI only at the time at which at least a portion of the electrical cutting current flows over the workpiece W and the arc is at least partially transferred to the workpiece W.
• the nozzle guard opening 250 of the plasma torch 1 can be positioned far enough away from the upper surface of the workpiece for piercing, and the arc still transitions.
• an arrangement according to the invention which ensures the fast, only a little time-delayed feeding and flowing after switching on the valve 63 of the secondary medium SGI, the nozzle cap 25 and the nozzle 21 are protected from high-injection molten hot material of the workpiece W to be machined. This is especially important for thick parts to be cut with thicknesses of approx. 20 mm.
• Cutting quality includes perpendicularity and inclination tolerance, roughness and beard attachment, as well as groove after-run (DIN EN ISO 9013).
• a non-flowing secondary medium SGI can also have a positive effect when crossing over kerfs F or when cutting corners or curves.
• the oscillation or pulsation of the plasma jet 6 can be reduced.
• Plasma torch 1 two parallel valves 63 and 64.
• the supply 61 of the secondary medium SGI is thus divided into the feeds 61a with the valve 64 and 61b with the valve 63.
• a shutter 65 is installed, which reduces the volume flow compared to the feed 61b, which can be achieved by the correspondingly smaller free cross section through which the secondary medium SGI can flow.
• the feeds 61a and 61b of the partial gas streams of secondary medium SGla and SGlb of the secondary gas SGI are here combined again in the plasma burner shaft 3.
• only one feed 61 to the plasma burner head 2 for the secondary medium SGI needs to be provided.
• this is advantageous.
• a reduction of the secondary medium flow has a positive effect at the same points in time as are the sections without flowing secondary medium SGI described in the example according to FIG.
• Transition operations such as grooving, cutting, passing over a joint F, cutting a corner or rounding be further improved.
• the nozzle 21 is fixed here by a nozzle cap 29. This allows a cooling medium, for example cooling water, to flow in the space between the nozzle 21 and the nozzle cap 22 (not shown).
• a cooling medium for example cooling water
• FIG. 3 shows, by way of example, a similar arrangement to FIG. 2, but the feeds 61a and 61b of the secondary media SGla and SGlb are merged to form the secondary medium SGI only in the plasma burner head 2.
• the merge takes place in the flow direction of the secondary medium SGI further ahead of the guide 27 of the secondary medium.
• FIG. 4 likewise shows an arrangement in which the feeds 61a and 61b of the secondary medium SGI are first brought together in the plasma burner head 2.
• the merging takes place from the nozzle cap 25 and the nozzle cap 29 in the flow direction of the secondary medium SGI to the gas guide 27 of the secondary medium.
• the gas guide 27 has two groups of openings, one group for the secondary medium SGla and the other group for the secondary medium SGlb.
• the openings differ in their design, di- dimensioning and / or alignment of their center axes (dash-dot lines), here for example in offset from the radial.
• the openings 271 and 272 of the groups can be arranged offset in different planes and in the planes in each case. This is also shown in FIG. 5.
• the secondary medium SGI can be split into two differently rotating
• Secondary medium streams SGla and SGlb and SGI and SG2 are divided, which ultimately flow around the plasma jet 6.
• a lower feed rate is for cutting small sections, for. B.
• small radii for example, be less than twice the thickness of the workpiece W, saw teeth, quadrilateral contours whose edge length is also less than twice the thickness of the workpiece W in the respective processing area, advantageous. Due to the lower feed speed, the guide system guides the plasma burner 1 more accurately even when the direction of movement changes. In addition, the plasma jet 6 does not run after, the groove trailing is reduced, which has a positive effect on corners on inner contours ( Figure 17) and inner corners.
• FIGS. 5a and b show, by way of example, a guide 27 for the secondary medium, here by way of example gas, which is designated here as secondary gas SG1, SG2, SGla and SGlb.
• the group of holes 271 are for the secondary medium SGI or SGla, the holes for the group 272 for the secondary medium SG2 or SGlb.
• the holes of a group are arranged in one plane.
• the group of holes 271 has, for example, an offset to the radial of 3 mm and the group of holes 272 no offset to the radial.
• openings there are also other openings than holes 271 and 272, such as. As grooves, squares, semicircular or angular shapes possible. Likewise, the openings may have different sized free cross sections through which secondary medium can escape.
• the arrangement according to FIG. 6 has the features of the example according to FIG. 1, but has, in addition to the feed 61 for the secondary medium SGI, a feed 62 for a second secondary medium SG2.
• the feeders 61, 62 may be outside the housing 30 hoses, which are connected to a supply line of the secondary media SGI, SG2 with a coupling unit 5.
• Each of the hoses is followed by another part of the feeders 61, 62 and in each case the valves 63, 64, which are arranged inside the housing 30.
• the feeds 61 and 62 of the secondary media SGI and SG2 are here combined again in the plasma burner shaft 3.
• only one feed 66 to the plasma burner head 2 needs to be provided for the secondary media SGI and SG2.
• the composition of the emerging secondary medium can also be effected by switching or simultaneously switching on the valves 63, 64.
• a secondary medium mixture containing a higher proportion of oxygen with respect to a content of nitrogen; C0 2 , air or argon as in large sections.
• the information given in the explanation in FIG. 4 applies here.
• such contours are also shown in FIGS. 15a and 15b.
• the oxygen content is then over 40 vol .-%.
• K3 is a small section and sections Kl and K5 are larger sections.
• Another application is the use of a liquid, for example
• Water as one of the secondary media used.
• the water After piercing through the workpiece W, the water is turned off and it flows a gas or gas mixture as the secondary medium SG2.
• the process can also be used for high-alloy steel and non-ferrous metals.
• Parameters such as flow velocity, flow rate, rotation and composition are changed.
• central axis When chamfering the plasma torch 1 (central axis) is not perpendicular to the workpiece surface as in perpendicular cutting, but is inclined to form a cutting edge with a certain angle. This is for further processing, usually a subsequent welding advantage. Since the effective thickness of the workpiece W to be cut changes (increases) during the transition from vertical to bevel cutting, modified parameters for a higher quality of cut then make sense. The same applies in principle to the transition from chamfering to vertical cutting (reduction)
• FIG. 7 shows, by way of example, a similar arrangement to FIG. 6, but the feeders 61 and 62 of the secondary media SGI and SG2 are first brought together in the plasma burner head 2.
• the merge takes place in the flow direction of the secondary media SGI, SG2 before the guide 27 for the secondary media.
• FIG. 8 likewise shows an arrangement in which the feeds 61 and 62 of the secondary media SGI, SG2 are first brought together in the plasma burner head 2.
• FIG. 8 has all the advantages of the example according to FIG.
• the guide 27 has two groups of openings, one group for the secondary medium SGI and the other group for the secondary medium SG2.
• the openings 271 and 272 differ in their design, here for example offset from the radial. This is also shown in FIG. 5a.
• the secondary medium SGI a different rotating secondary fluid flow than the secondary medium SG2, which ultimately flow around the plasma jet 6, form.
• a lower feed rate is for cutting small sections, for. B.
• small radii for example, be less than twice the thickness of the workpiece W in the respective processing area, for example, sawtooth contours, quadrilateral contours whose edge length is also less than twice the workpiece thickness in the respective processing area, advantageous.
• the guide system guides the plasma torch 1 more accurately even when the direction of movement of the feed movement is changed.
• the plasma jet 6 does not run after, the groove trailing is reduced, which has a positive effect on corners on inner contours and inner corners. In long sections, this does not matter, here can be quickly cut with large rotation of the flow of / the secondary medium / media.
• FIG. 9 additionally shows in the supply 34 of the plasma gas PG1 a valve 31 in the housing 30 of the plasma burner shaft 3, which switches the plasma gas PG1 on and off.
• the valve 33 serves to vent the cavity 11, which is necessary in particular at the end of the cut in order to ensure a rapid outflow of the plasma gas PG1.
• FIG. 10 shows, in addition to FIG. 9, the supply 35 of a further plasma gas PG2, which is supplied via a gas hose 35 and a valve 31 analogous to plasma gas PG1. This can be done by switching and switching the valves 31 and 32, a change of the plasma gases PG1 or PG2 depending on the process state.
• the valve 33 also serves to vent the cavity 11.
• Figure 11 shows the greatly simplified construction of an axial solenoid valve, as can be used in the invention in the feeds for secondary media and plasma gas. Inside his body is the coil S with the
• Windings flowing through the plasma gas from input E to output A. can be arranged. Inside, the mechanism for opening and closing is arranged.
• the body of the solenoid valve has a length L and an outer diameter D.
• the solenoid valve shown here has a length L of 25 mm and a diameter of 10mm.
• Figure 12 shows a possible space-saving arrangement of the valves 31, 63 and 64. They are arranged in the housing 30 so that they are arranged in a plane perpendicular to the center line M at an angle al, of 120 °. The deviation from this angle should not exceed ⁇ 30 °. As a result, the arrangement is space-saving and can be arranged in the housing 30 or plasma torch shaft 3.
• the distances between the central longitudinal axes LI, L2 and L3 between the valves 31, 32, 33 are each ⁇ 20mm.
• at least one valve with its inlet E is opposite to the other valves, i. aligned to their outputs A.
• the oppositely directed valve is the valve 33 in the example shown
• Figure 13 shows an arrangement with four valves 31, 33, 63 and 64. They are arranged in the interior of the housing 30 so that they are arranged in a plane perpendicular to the center line M at angles al, a2, a3, a4 of 90 ° ,
• the valves 31, 33, 63 and 64 are arranged in the interior of the housing 30 so that they are arranged in a plane perpendicular to the center line M at angles al, a2, a3, a4 of 90 ° , The
• Deviation from these angles should not exceed ⁇ 30 °.
• the arrangement is space-saving and can be arranged in the housing 30 or plasma torch shaft 3.
• the distances of the central longitudinal axes LI, L2, L3 and L4 of the valves 31, 33, 63 and 64 are ⁇ 20 mm.
• at least one valve is opposite its inlet E to the other valves, i. aligned to their outputs A.
• Figure 14 shows an arrangement with four valves 31, 33, 63 and 64 and another valve 32. They are arranged in the interior of the housing 30 so that they in a plane perpendicular to the center line M at angles al, a2, a3, a4 , a5 are arranged by 72 °. The deviation from these angles should not exceed ⁇ 15 °. As a result, the arrangement is space-saving and can be arranged in the housing 30 or plasma torch shaft 3.
• the distances between the middle longitudinal axes LI, L2, L3, L4 and L5 between the valves are ⁇ 20 mm.
• Of these valves 31 to 33 is at least one valve with his Input E opposite to the other valves, ie aligned to the outputs A.
• FIG. 15 a shows a schematic contour guidance of a plasma torch for cutting a contour from a workpiece W as viewed from above onto the workpiece and
• FIG. 15 b shows the resulting workpiece in a perspective view.
• a workpiece with two long sections, contour Kl, K5 and several short sections, contour K3, is to be cut.
• Section K0 is the beginning of cutting, it is there pierced into the workpiece.
• the sections contours K2 and K4 are due to cutting technology to achieve a sharp corner and are located in the so-called "waste part", they are not part of the cut workpiece.
• the secondary medium is not yet needed. It even disturbs and shortens the jet of plasma 6 emerging from the nozzle 21 even as it flows sideways. Therefore, the plasma torch 1 must be positioned with its nozzle guard opening 250 at a smaller distance from the workpiece surface ( Figure 17, distance d). This in turn leads to endangerment of the nozzle cap 25 and the nozzle 21 by hot high-rate molten material. Remedy here creates the connection of the secondary medium only at the time at which at least a portion of the electrical cutting current flows over the workpiece and the arc is at least partially transferred to the workpiece.
• the nozzle protection cap opening 250 of the plasma torch 1 can be positioned for piercing at a greater distance d from the workpiece surface, and the arc nevertheless sets over.
• the nozzle cap 25 and the nozzle 21 are protected from high-injection molten hot material of the workpiece to be machined. This is particularly important for thick workpieces to be cut starting from approx. 20 mm in the respective machining area.
• a plasma torch 1 according to FIGS. 1 to 10 can be used for this purpose.
• Secondary medium should flow from the nozzle protection cap opening 250 at the earliest at the time at which the workpiece has been punctured at least 1/3, better half, and preferably completely when piercing a workpiece.
• a plasma torch according to FIGS. 1 to 10 can be used for this purpose.
• a plasma torch 1 according to FIGS. 4 and 8 can be used for this purpose. Due to the greater offset of the openings 271 and 272 from the radial in the gas guide 27 for the secondary media, the secondary media SGla and SGlb (FIG. 4) and SGI and SG2 (FIG. 8) rotate to different degrees.
• the change of the rotation of the secondary medium or the secondary media should be carried out at the earliest at the time from the nozzle guard opening 250 at which the workpiece has been pierced at least 1/3, better half and best completely completely when piercing a workpiece.
• the change from water to gas as a secondary medium should be made at the earliest at the time from the Düsenschutzkappenö réelle 250 at which the workpiece has been pierced at least to 1/3, better half and best completely completely when piercing a workpiece.
• the process can also be used for high-alloy steel and non-ferrous metals.
• a plasma torch 1 according to FIGS. 6 and 10 can be used for this purpose.
• Secondary medium mixture is inserted, because then the melt is thinner and the piercing is faster.
• too high an oxygen content can again lead to the formation of irregularities on the cutting edge or surface.
• a change of the secondary medium between the piercing and the cutting may be advantageous.
• the change of outflowing secondary medium should be made at the earliest at the time from the Düsenschutzkappenö réelle 250 at which the workpiece has been at least 1/3, better half and best completely pierced when inserting into a workpiece.
• a plasma torch 1 according to FIGS. 6 and 10 can be used for this purpose.
• the secondary medium and the rotation of the flow of the secondary medium are changed during insertion into the workpiece.
• the secondary medium (s) may be changed to one or more parameters, such as flow rate, volumetric flow, flow and composition rotation during the plunge phase, as compared to other operating conditions.
• the cutting movement is made with the selected secondary medium.
• the long section Kl is cut, after which the section K2 is to be moved around the corner.
• a sharp-edged corner is obtained when the plasma cutting torch 1 is guided as in corner section contour K2.
• the plasma cutting torch 1 leaves the contour of the part to be cut, and is passed over the "waste part" to return to the contour of the part to be cut, which is also called the "corner swept".
• a section contour K3 follows with an exemplary sequence of small sections with advancing axis direction changes. During the time in which the plasma torch 1 is guided over the "waste part" in the section contour K2, at least one change took place on the outflowing secondary medium.
• a plasma torch 1 according to FIGS. 4 and 8 can be used for this purpose.
• a plasma torch 1 according to FIGS. 6 to 10 can be used for this purpose.
• a plasma torch according to the figures 8 can be used.
• the secondary medium or secondary medium mixture with one or more parameters, such as, for example, flow velocity, volume flow, rotation the flow and composition during cutting and particularly advantageous when driving over the "waste part" to change.
• the contour K3 with the small sections is cut with the parameter (s) most suitable therefor.
• Figures 16a and 16b also show a cut component. Again, as described in Figures 15a and 15b, the form of the change of the outflowing secondary medium in the sections K2 and K4 between the sections Kl and K3 and K5. The parameters of the effluent secondary medium for the section are changed from section K21 because in section K3 a bevel with an angle, for example se 45 ° is cut. This is also described in the last paragraph to FIG.
• FIG. 17 shows, by way of example, a plasma burner 1 with its positioning relative to the workpiece with the distance d between nozzle protection cap 25 and workpiece W.

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• 2016
  • 2016-08-01 DE DE102016214146.5A patent/DE102016214146A1/de active Pending
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