Indian Patents. 270952:PLASMA TORCH HEAD, PLASMA TORCH SHAFT AND PLASMA TORCH

Title of Invention	PLASMA TORCH HEAD, PLASMA TORCH SHAFT AND PLASMA TORCH
Abstract	The invention relates to a plasma torch head, plasma torch shaft and a plasma torch that permit the plasma torch head to be simply and rapidly replaced.

Full Text	New application K10520PCT Kjellberg Finsterwalde Elektroden & Maschinen GmbH, Leipziger Strasse 82, D-03238 Finsterwalde “Plasma torch head, plasma torch shaft and plasma torch” The present invention relates to a plasma torch head, comprising at least one fluid passage, an electrode, a nozzle, a current conductor and a bearing surface on a bear¬ing side, a plasma torch shaft, comprising at least one feed line for a gas, a current supply line, at least one fluid passage, a current conductor and a bearing surface on a bearing side and a plasma torch with at least one feed line for a gas, an electrode, a nozzle and a current supply line, the plasma torch comprising a plasma torch shaft containing at least one first fluid passage, a first current conductor and a first bearing surface on a bearing side, and a plasma torch head containing at least one second fluid passage, a second current conductor and a second bearing surface on a bearing side, the first and second bearing surfaces resting axially relative to one another, and the at least one first fluid passage being in fluid connection with the at least one sec¬ond fluid passage, and the first current conductor being in electric connection with the second current conductor. Plasma torches are known which consist of a plasma torch shaft and a plasma torch head, which can be joined together by means of a quick change connector. In the plasma torch head there are the parts of the plasma torch which wear quickly in operation and have to be replaced frequently. These are above all the electrode, the nozzle and the cover guard. However, it may also be necessary to change from one plasma torch cutting head to another in the case of varying uses of the plasma pro¬cess, such as between cutting structural steel and cutting stainless steel. In order to do this quickly, a quick change connector is helpful. G 081 32 660 describes a plasma torch consisting of a plasma torch shaft, an attach¬able connector and a plasma torch head. The plasma torch has a locking pin project¬ing from the coupling surface and a corresponding hole on the opposing coupling surface, in which the locking pin can be inserted when precisely radially adjusted. The plasma torch shaft and the connector are connected in bayonet fashion by means of a sleeve, which can be displaced on the plasma torch shaft, with guide pins that can be inserted into corresponding axial and radial guide grooves in the connector, by subjecting the sleeve to axial pressure and radial movement. Both in the case of manual operation and in the case of automated systems, it is inconvenient first to introduce the locking pin into the hole and then to connect the other contacts for the delivery and supply lines. In addition, damage cannot be ruled out. DE 695 11 728 T2 describes an alignment means and a method for an arc plasma torch system. The arc plasma torch consists of an arc plasma torch shaft and an arc plasma torch head. An overall positioning guide is used in order to align the arc plasma torch with a seat at the beginning. The seat may be a bevelled edge. The seat has two passages with a receiving end and an upper side which are dimensioned such that alignment pins with a specific diameter are received. The alignment pins also have apertures which can permit a gas or fluid to pass through. The surface diameter is greater than the passage diameter and can thus compensate for minor misalignments. A central passage is similarly dimensioned and can likewise conduct a gas or fluid through. In the case of incorrect positioning, damage can be caused to the alignment pins if a force acts in the axial direction of the arc plasma torch after the central passage has been inserted. If the alignment pins are used simultaneously as a passageway for a gas or fluid, this can lead to leaks. Damage to the alignment pins makes it difficult to position and connect the components of the arc plasma torch later, especially if a slight tolerance is required in the axes of the arc plasma torch head and the seat. In addition, the insertion of two cylindrical bodies of a plasma torch is known in principle. There is, however, a risk of joining the wrong connections together and/or of damaging them. A further point is that it is often required for the connection to be highly centred. Then, the play between an inner and outer cylinder must be very small. That again makes it difficult to join the parts together. The invention is therefore based on the problem of providing a quick change possi¬bility for the plasma torch head. According to the invention, this problem is solved in the plasma torch head of the kind mentioned at the beginning in that, on its bearing side, it has a cylinder wall with an outer surface and an annular surface, nVer similar radial indentations and nVor similar radial projections being provided peripherally on the outer surface, where nVer, nVor is = 0 and nVer + nVor is = 5, and in the event that n = 5, the sum of two ad¬jacent angles at the centre by which the projections and indentations or one projec¬tion and one indentation are offset from one another is not = 180° and the five angles at the centre are different in size, or in the event that n > 5, the sum of two adjacent angles at the centre by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre are different in size or at least two of the n > 5 angles at the centre are equal in size, and then in each case the sum of the respective angles at the centre occurring twice and the adjacent angles at the centre on either side thereof is The current conductor can be implemented in integrated and/or separate form in the fluid passageways. Normally, there are at least three fluid passageways, namely for supplying gas, such as plasma gas, and the feed and return lines for coolant. In addition, this problem is solved in the plasma torch shaft of the kind mentioned at the beginning in that, on its bearing side, it has a cylinder wall with an outer surface, nVor similar radial projections and nVer similar radial indentations being provided peripherally on the outer surface, where nVor, nVer is = 0 and nVor + nVer is = 5, and in the event that n = 5, the sum of two adjacent angles at the centre by which the pro¬jections and indentations or one projection and one indentation are offset from one another is not = 180° and the five angles at the centre are different in size, or in the event that n > 5, the sum of two adjacent angles at the centre by which the projec¬tions and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre are different in size or at least two of the n > 5 angles at the centre are equal in size, and then in each case the sum of the respective angles occurring twice at the centre and the adjacent angles at the centre on either side thereof is The plasma torch heads and shafts may be plasma cutting or plasma welding heads and shafts, respectively. In addition, this problem is solved in the plasma torch shaft of the kind mentioned at the beginning in that one of the plasma torch shaft and the plasma torch head has, on its bearing side, a first cylinder wall with an outer surface and an annular surface and an external diameter D21a, and the other of the plasma torch shaft and the plasma torch head has, on its bearing side, a second cylinder wall with an inner surface and internal diameter D31a, where D31a is > D21a, and nVor similar radial projections and nVer similar radial indentations being provided peripherally on the inner surface, where nVor, nVer is = 0 and nVor + nVer = n = 5, and a similar number of corresponding indentations or projections in engagement with them being provided on the outer surface, the projections and indentations further being arranged such that when the plasma torch shaft is connected to the plasma torch head, the projections and inden¬tations first have to be brought into engagement before the first bearing surface and the second bearing surface come to abut each other, and in the event that n = 5, the sum of two adjacent angles at the centre by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the five angles at the centre are different in size, or in the event that n > 5, the sum of two adjacent angles at the centre by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre are different in size or at least two of the n > 5 angles at the centre are equal in size, and then in each case the sum of the respective angles oc¬curring twice at the centre and the adjacent angles at the centre on either side thereof is The plasma torch can be a plasma cutting or welding torch. In the plasma torch head, it can be provided that the sum of two adjacent angles at the centre is = 170°. In this way, an even more stable abutment of the annular sur¬face and projections in the joint position is achieved. According to a particular embodiment of the invention n = 5 and the sum of two ad¬jacent angles at the centre is not repeated. According to a further particular embodiment, the plasma torch head contains four fluid passageways. The at least one fluid passage is advantageously provided with a connector. The current conductor is conveniently likewise provided with a connector. In addition, it can be provided that indentations are rectangular grooves. It goes without saying that the grooves can also be any other shape, such as arcuate, triangu¬lar etc. According to a further particular embodiment, nVer is = 5. Alternatively, it is also conceivable that nVor is = 5. The dependent claims concerning the plasma torch shaft relate to advantageous fur¬ther improvements thereof. On the inner surface of the cylinder wall, a peripheral chamfer extending radially outwards can, for example, be provided towards the bearing side before the projec¬tions. This makes it easier to join the parts together, because a larger diameter is available at the beginning of the joining action. The dependent claims concerning the plasma torch relate to advantageous further improvements thereof. One particular embodiment of the plasma torch, for example, is characterised by the fact that the plasma torch head has the first cylinder wall and the plasma torch shaft has the second cylinder wall. The invention is based on the surprising finding that the specific number and ar¬rangement of projections and corresponding indentations makes it possible to join the plasma torch head and plasma torch shaft together quickly and easily, without jamming. It is merely necessary for the annular surface to be simply brought to rest against the projections, i.e. to be placed in a joining position, and then to be turned relative to the projections until the joint position is reached, in which, when an axial force is applied, the projections and indentations engage with one another. This is particularly advantageous in situations in which the plasma torches are clamped in and are not visually accessible. The rapid exchange of the plasma torch head can be carried out blind, as it were. In addition, the invention offers a quick-change connection between the plasma torch head and the plasma torch shaft with protection against twisting, a small tole¬rance between the axes of the plasma torch head and the plasma torch shaft and a high degree of centralisation. The fluid passageways both for the gas, and also as plasma and secondary gas, and for the coolant, can also be used for transporting current. Further features and advantages of the invention will become clear from the claims the following description, in which two embodiments of the invention are illustrated in detail with reference to the schematic drawings. There, Figure 1 shows a side view of a front part of a plasma cutting torch before the plasma cutting torch head and plasma cutting torch shaft are joined together, in accordance with a particular em¬bodiment of the present invention, partially in section; Figure 2 shows a side view of the front part of the plasma cutting torch while the plasma cutting torch head and plasma cutting torch shaft are being joined together in the joint position, partially in section; Figure 3a shows a plan view of the plasma cutting torch shaft from the bearing side; Figure 3b shows a plan view of the plasma cutting torch head from the bearing side; Figure 4a shows a sectional view of the plasma cutting torch head and shaft in the joining position in the region of the indentations and projections; Figure 4b shows a sectional view of the plasma cutting torch head and shaft in the joint position in the region of the indentations and projections; Figure 5 shows a side view of the front part of the plasma cutting torch after the plasma cutting torch head and plasma cutting torch shaft have been joined together, partially in section; Figure 6 shows a section of Figure 2; Figures 6a to 6f show a detail from Figure 6 in various embodiments; Figure 7 shows various embodiments of indentations and/or projec¬tions; Figure 8 shows details from Figure 4b; and Figure 9 shows a view similar to Figure 4a. As can be seen from Figures 1 and 2, a plasma cutting torch 1 comprises a plasma cutting torch head 2 and a plasma cutting torch shaft 3. As can be seen with refer¬ence to Figures 3a and 3b and also Figure 5, the plasma cutting torch head 2 has a first bearing surface (not shown), a connector 241 for water feed, a connector 242 for water return, a connector 243 for plasma gas, a connector 244 for secondary gas and a connector 245 for pilot current. The connectors 241 to 245 are provided with holes (not indicated) for the passage of gas or fluids. The plasma cutting torch shaft 3 has a second bearing surface (not shown), a socket 341 for water return, a socket 342 for water feed, a socket 343 for plasma gas, a socket 344 for secondary gas and a socket 345 for pilot current. The connectors 241 to 245 and the sockets 341 to 345 form a quick-change inter¬face. It goes without saying that, the connectors or some of them can alternatively be disposed on the plasma cutting torch shaft and the sockets on the plasma cutting torch head. The fluid passageways and current lines in the plasma cutting torch head 2 and in the plasma cutting torch shaft 3, which are needed for supply purposes are not illustrated in detail . The plasma cutting torch head 2 has a first cylinder wall 21 on its bearing side with an outer surface 21a and an annular surface 22 and an external diameter D21a. The plasma cutting torch shaft 3 has a second cylinder wall 31 on its bearing side with an inner surface 31a and an internal diameter D31a, where D31a is > D21a. In order to insert the plasma cutting torch head 2 into the plasma cutting torch shaft 3, the latter has considerable play S in the joining position (see Figures 6a, 6d, 6e and 6f). As can be seen from Figures 3a and 3b, the plasma cutting torch shaft 3 has five similar rectangular lugs 331, 332, 333, 334 and 335 peripherally on its inner surface 31a, and the plasma cutting torch head 2 has five similar correspondingly designed and arranged rectangular grooves 231, 232, 233, 234 and 235 on its outer surface 21a. The lugs 331 to 335 and grooves 231 to 235 are arranged in the axial direction in such a way that when the plasma cutting torch shaft 3 is joined to the plasma cut¬ting torch head 2, the grooves and lugs are first engaged before the first bearing sur¬face and the second bearing surface come into abutment. When the plasma cutting torch head 2 is inserted into the plasma cutting torch shaft 3, the annular surface 22 of the plasma cutting torch head 2 usually encounters the lugs 331 to 335 (see Figure 4a). The plasma cutting torch head 2 and the plasma cut¬ting torch shaft 3 are thus located in the joining position. Since the sum of two adjacent angles at the centre of the angles at the centre ?, ?, ?, ? and ? (see Figure 8) at which the grooves 231 to 235 are arranged is not = 180°, and the five angles at the centre are different in size, the lugs 331 to 335 together with the annular surface 22 of the plasma cutting torch head interrupted by the grooves 231 to 235 form a virtual closed surface A relative to one another in any position except the joint position (see Figure 4b). With the exception of the joint position, the grooves 231 to 235 are always arranged such that the lugs resting on the annular surface 22 of the plasma cutting torch head 2 (in Figure 4a the lugs 331, 333, 334 and 335) form a quadrangle with the area A, in which the centre axis M of the plasma cutting torch 1 is located (see Figure 4a). If the additional condition is not met that the sum of two adjacent angles at the cen¬tre of the angles at the centre ?, ?, ?, ? and ? is repeated, only a triangular area A can be formed, as is shown in Figure 9. Because of the fact that the centre axis M of the plasma cutting torch 1 is located in the area A, the plasma cutting torch shaft 3 and the plasma cutting torch head 2 can be twisted in any direction relative to one another until the joint position is reached. Once the joint position is reached, the plasma cutting torch head 2 slides into the plasma cutting torch shaft 3 under the effect of an axial force, and the two can be in¬serted into one another (see Figures 2, 4b and 5). By turning a clamping sleeve 25, a further axial force is exerted on the interface via the internal threads 251 of the clamping sleeve and the external threads 35 of the plasma cutting torch shaft 3, until the final joint position is reached (see Figure 5). There, the diameter of the plasma cutting torch shaft is reduced from D31a to D31b, as a result of which the play S is reduced or even eliminated completely and the cen¬tricity is increased. This can of course also be achieved by other mechanisms, such as a bayonet fitting or some other tightening means. The grooves 231 to 235 are usually larger than the lugs 331 to 335, since it would not otherwise be possible to join them together. The dimension B stands for the cen¬tral width of the grooves and lugs and is calculated (see Figures 3a and 3b) as fol¬lows . The similar design of the grooves and lugs means that the production effort is reduc¬ed compared to an embodiment with different lugs and thus grooves, in which three grooves and lugs would be sufficient. It is then possible to work with a single tool. To simplify the joining process, the inner surface 31a can be designed differently. It can have greater play S with a cylindrical shape (Figure 6a), an angle F (Figure 6b) a radius (Figure 6c) or a combination of the individual elements (Figures 6d, 6e and 6f). It is sufficient for the grooves and lugs to be substantially similar in shape and size. It is only necessary for them to be designed such that the condition with the polygon, such as a triangle or quadrangle for example, are met. The dimensions may look as follows, for example: The central diameter D of the first cylinder wall and the second cylinder wall is cal¬culated as follows (see Figure 1): . D: 25 to 100mm F: 15 to 60° S: 0.2 to 0.7mm R: 1 to 5mm. In Figure 8 the parameters look as follows: ? = 75° ? = 70° ? = 90° ? = 65° ? = 60°. In addition, the spaces a, b, c, d and e between the lugs/grooves are shown in Figure 8. These are the spaces between the axes of symmetry of the lugs and grooves 231 to 235 on the central diameter D. They are calculated according to the formula: in mm in mm etc. In Figure 9, the angles are selected as follows: ? = 60° ? = 95° ? = 80° ? = 75° ? = 50°. ? + ? = ? + ? 60° + 95° = 80° + 75° = 155°. Consequently, the sum of two adjacent angles at the centre, namely of ? and ? and of ? and ? is repeated. Figure 7 shows examples of possible designs of pairs of lugs 331 and grooves 231. The lugs could, however, also be used as grooves and the grooves as lugs. The features of the invention disclosed in the present description, in the drawings and in the claims can be essential to implementing the invention in its various em¬bodiments both individually and in any combinations. Claims 1. A plasma torch head (2), comprising at least one fluid passage, an electrode, a nozzle, a current conductor and a bearing surface on a bearing side, characterised by the fact that on its bearing side, it has a cylinder wall (21) with an outer surface (21a) and an annular surface (22), where nVer similar radial indentations and nVor similar radial projections are provided peripherally on the outer surface (21a), where nVer, nVor are = 0 and nVer + nVor is = 5, and in the event that n = 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180°, and the five angles at the centre (?, ?, ?, ?, ?) are different in size, or in the event that n > 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre (?, ?, ?, ?, ?) are different in size or at least two of the n > 5 angles at the centre (?, ?, ?, ?, ?) are equal in size, and then in each case the sum of the respective angles at the centre (? or ? or ? or ? or ?) occur¬ring twice and the adjacent angles at the centre on either side thereof (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is 2. The plasma torch head (2) as claimed in claim 1, characterised by the fact that the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is = 170°. 3. The plasma torch head (2) as claimed in either of claims 1 or 2, characterised by the fact that n = 5 and the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is not repeated. 4. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that it includes four fluid passageways. 5. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that the at least one fluid passage is provided with a connector (241, 242, 243, 244). 6. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that the current conductor is provided with a connector (245). 7. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that the indentations are rectangular grooves (231, 232, 233, 234, 235). 8. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that nVer is = 5. 9. The plasma torch head (2) as claimed in any of claims 1 to 7, characterised by the fact that nVor is = 5. 10. A plasma torch shaft (3), comprising at least one feed line for a gas, a current supply line, at least one fluid passage, a current conductor and a bearing surface on a bearing side, characterised in that on its bearing side, it has a cylinder wall (31) with an inner surface (31a), where nVor similar radial projections and nVer similar radial indentations are provided peripherally on the inner surface (31a), where nVor, nVer are = 0 and nVor + nVer is = 5, and in the event that n = 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180°, and the five angles at the centre (?,?, ?, ?, ?) are different in size, or in the event that n > 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre (?, ?, ?, ?, ?) are different in size or at least two of the n > 5 angles at the centre (?, ?, ?, ?, ?) are equal in size, and then in each case the sum of the respective angles at the centre (? or ? or ? or ? or ?) occur¬ring twice and the adjacent angles at the centre on either side thereof (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is 11. The plasma torch shaft (3) as claimed in claim 10, characterised by the fact that the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is = 170°. 12. The plasma torch shaft (3) as claimed in either of claims 10 or 11, characterised by the fact that n = 5 and the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ?) is not repeated. 13. The plasma torch shaft (3) as claimed in any of claims 10 to 12, characterised by the fact that, in addition, a feed line for secondary gas is provided and it includes four fluid passageways. 14. The plasma torch shaft (3) as claimed in any claims 10 to 13, characterised by the fact that the at least one fluid passage is provided with a socket (341, 342, 343, 344). 15. The plasma torch shaft (3) as claimed in any claims 10 to 14, characterised by the fact that the current conductor is provided with a socket (345). 16. The plasma torch shaft (3) as claimed in any claims 10 to 15, characterised by the fact that the projections are rectangular lugs (331, 332, 333, 334, 335). 17. The plasma torch shaft (3) as claimed in any claims 10 to 16, characterised by the fact that a peripheral chamfer extending radially outwards is provided on the inner surface (31a) of the cylinder wall (31) towards the bearing side before the projections and/or indentations . 18. The plasma torch shaft (3) as claimed in any of claims 10 to 17, characterised by the fact that nVor is = 5. 19. The plasma torch shaft (3) as claimed in any of claims 10 to 17, characterised by the fact that nVer is = 5. 20. A plasma torch (1), comprising at least one feed line for a gas, an electrode, a nozzle and a current supply line, the plasma torch (1) including a plasma torch shaft (3) which has at least one first fluid passage, a first current conductor and a first bearing surface on a bearing side, and comprises a plasma torch head (2) which includes at least one second fluid pas¬sage, a second current conductor and a second bearing surface on a bearing side, the first and second bearing surfaces resting axially relative to one another, and the at least one first fluid passage being in fluid connection with the at least one second fluid passage, and the first current conductor being in electric connection with the second current conductor, characterised by the fact that one of the plasma torch shaft (3) and the plasma torch head (2) has, on its bear¬ing side, a first cylinder wall (21) with an outer surface (21a) and an annular sur¬face (22) and an external diameter D21a, and the other of the plasma torch shaft (3) and the plasma torch head (2) has, on its bearing side, a second cylinder wall (31) with an inner surface (31a) and an internal diameter D31a, where D31a is > D21a, and nVor similar radial projections and nVer similar radial indentations being provided peripherally on the inner surface (31a), where nVor, nVer is = 0 and nVor + nVer = n = 5, and a similar number of corresponding indentations or pro¬jections in engagement with them being provided on the outer surface (21a), the projections and indentations further being arranged such that when the plasma torch shaft (3) is connected to the plasma torch head (2), the projections and in¬dentations first have to be brought into engagement before the first bearing sur¬face and the second bearing surface come to abut each other, and in the event that n = 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180°, and the five angles at the centre (?,?, ?, ?, ?) are different in size, or in the event that n > 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre (?, ?, ?, ?, ?) are different in size or at least two of the n > 5 angles at the centre (?, ?, ?, ?, ?) are equal in size, and then in each case the sum of the respective angles at the centre (? or ? or ? or ? or ?) occur¬ring twice and the adjacent angles at the centre on either side thereof (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is 21. The plasma torch shaft (1) as claimed in claim 20, characterised by the fact that the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is = 170°. 22. The plasma torch (1) as claimed in either of claims 20 or 21, characterised by the fact that n = 5 and the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is not repeated. 23. The plasma torch (1) as claimed in any of claims 20 to 22, characterised by the fact that, in addition, a feed line for secondary gas is provided and the plasma torch shaft (3) includes four first fluid passageways and the plasma torch head (2) includes four second fluid passageways. 24. The plasma torch (1) as claimed in any of claims 20 to 23, characterised by the fact that the coolant is water. 25. The plasma torch (1) as claimed in any claims 20 to 24, characterised by the fact that the at least one first fluid passage is provided with a socket (341, 342, 343, 344). 26. The plasma torch (1) as claimed in any claims 20 to 25, characterised by the fact that the at least one second fluid passage is provided with a connector (241, 242, 243, 244). 27. The plasma torch (1) as claimed in any claims 20 to 26, characterised by the fact that the first current conductor is provided with a socket (345). 28. The plasma torch (1) as claimed in any claims 20 to 27, characterised by the fact that the second current conductor is provided with a socket (245). 29. The plasma torch (1) as claimed in any claims 20 to 28, characterised by the fact that the plasma torch head (2) has the first cylinder wall (21) and the plasma torch shaft (3) has the second cylinder wall (31). 30. The plasma torch (1) as claimed in any claims 20 to 29, characterised by the fact that the indentations are rectangular grooves (231, 232, 233, 234, 235). 31. The plasma torch (1) as claimed in any claims 20 to 30, characterised by the fact that a peripheral chamfer extending radially outwards is provided on the inner surface (31a) of the second cylinder wall (31) towards the bearing side before the projections and/or indentations . 32. The plasma torch (1) as claimed in any of claims 20 to 31, characterised by the fact that nVor is = 5. 33. The plasma torch (1) as claimed in any of claims 20 to 31, characterised by the fact that nVer is = 5. 34. The plasma torch (1) as claimed in any claims 20 to 33, characterised by the fact that a holding means for holding the plasma torch head and the plasma torch shaft (3) together is provided. 35. The plasma torch (1) as claimed in claim 34, characterised by the fact that the holding means is a clamping sleeve. Abstract A plasma torch head, a plasma torch shaft and a plasma torch for providing a quick and simple possibility of changing the plasma torch head are described.

Full Text

New application
K10520PCT

Kjellberg Finsterwalde Elektroden & Maschinen GmbH, Leipziger Strasse 82, D-03238
Finsterwalde
“Plasma torch head, plasma torch shaft and plasma torch”

The present invention relates to a plasma torch head, comprising at least one fluid passage, an electrode, a nozzle, a current conductor and a bearing surface on a bear¬ing side, a plasma torch shaft, comprising at least one feed line for a gas, a current supply line, at least one fluid passage, a current conductor and a bearing surface on a bearing side and a plasma torch with at least one feed line for a gas, an electrode, a nozzle and a current supply line, the plasma torch comprising a plasma torch shaft containing at least one first fluid passage, a first current conductor and a first bearing surface on a bearing side, and a plasma torch head containing at least one second fluid passage, a second current conductor and a second bearing surface on a bearing side, the first and second bearing surfaces resting axially relative to one another, and the at least one first fluid passage being in fluid connection with the at least one sec¬ond fluid passage, and the first current conductor being in electric connection with the second current conductor.
Plasma torches are known which consist of a plasma torch shaft and a plasma torch head, which can be joined together by means of a quick change connector. In the plasma torch head there are the parts of the plasma torch which wear quickly in operation and have to be replaced frequently. These are above all the electrode, the nozzle and the cover guard. However, it may also be necessary to change from one plasma torch cutting head to another in the case of varying uses of the plasma pro¬cess, such as between cutting structural steel and cutting stainless steel. In order to do this quickly, a quick change connector is helpful.
G 081 32 660 describes a plasma torch consisting of a plasma torch shaft, an attach¬able connector and a plasma torch head. The plasma torch has a locking pin project¬ing from the coupling surface and a corresponding hole on the opposing coupling surface, in which the locking pin can be inserted when precisely radially adjusted. The plasma torch shaft and the connector are connected in bayonet fashion by means of a sleeve, which can be displaced on the plasma torch shaft, with guide pins that can be inserted into corresponding axial and radial guide grooves in the connector, by subjecting the sleeve to axial pressure and radial movement. Both in the case of manual operation and in the case of automated systems, it is inconvenient first to introduce the locking pin into the hole and then to connect the other contacts for the delivery and supply lines. In addition, damage cannot be ruled out.
DE 695 11 728 T2 describes an alignment means and a method for an arc plasma torch system. The arc plasma torch consists of an arc plasma torch shaft and an arc plasma torch head. An overall positioning guide is used in order to align the arc plasma torch with a seat at the beginning. The seat may be a bevelled edge. The seat has two passages with a receiving end and an upper side which are dimensioned such that alignment pins with a specific diameter are received. The alignment pins also have apertures which can permit a gas or fluid to pass through. The surface diameter is greater than the passage diameter and can thus compensate for minor misalignments. A central passage is similarly dimensioned and can likewise conduct a gas or fluid through. In the case of incorrect positioning, damage can be caused to the alignment pins if a force acts in the axial direction of the arc plasma torch after the central passage has been inserted. If the alignment pins are used simultaneously as a passageway for a gas or fluid, this can lead to leaks. Damage to the alignment pins makes it difficult to position and connect the components of the arc plasma torch later, especially if a slight tolerance is required in the axes of the arc plasma torch head and the seat.
In addition, the insertion of two cylindrical bodies of a plasma torch is known in principle. There is, however, a risk of joining the wrong connections together and/or of damaging them.
A further point is that it is often required for the connection to be highly centred. Then, the play between an inner and outer cylinder must be very small. That again makes it difficult to join the parts together.
The invention is therefore based on the problem of providing a quick change possi¬bility for the plasma torch head.
According to the invention, this problem is solved in the plasma torch head of the kind mentioned at the beginning in that, on its bearing side, it has a cylinder wall with an outer surface and an annular surface, nVer similar radial indentations and nVor similar radial projections being provided peripherally on the outer surface, where nVer, nVor is = 0 and nVer + nVor is = 5, and in the event that n = 5, the sum of two ad¬jacent angles at the centre by which the projections and indentations or one projec¬tion and one indentation are offset from one another is not = 180° and the five angles at the centre are different in size, or in the event that n > 5, the sum of two adjacent angles at the centre by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre are different in size or at least two of the n > 5 angles at the centre are equal in size, and then in each case the sum of the respective angles at the centre occurring twice and the adjacent angles at the centre on either side thereof is The current conductor can be implemented in integrated and/or separate form in the fluid passageways.
Normally, there are at least three fluid passageways, namely for supplying gas, such as plasma gas, and the feed and return lines for coolant.
In addition, this problem is solved in the plasma torch shaft of the kind mentioned at the beginning in that, on its bearing side, it has a cylinder wall with an outer surface, nVor similar radial projections and nVer similar radial indentations being provided peripherally on the outer surface, where nVor, nVer is = 0 and nVor + nVer is = 5, and in the event that n = 5, the sum of two adjacent angles at the centre by which the pro¬jections and indentations or one projection and one indentation are offset from one another is not = 180° and the five angles at the centre are different in size, or in the event that n > 5, the sum of two adjacent angles at the centre by which the projec¬tions and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre are different in size or at least two of the n > 5 angles at the centre are equal in size, and then in each case the sum of the respective angles occurring twice at the centre and the adjacent angles at the centre on either side thereof is The plasma torch heads and shafts may be plasma cutting or plasma welding heads and shafts, respectively.
In addition, this problem is solved in the plasma torch shaft of the kind mentioned at the beginning in that one of the plasma torch shaft and the plasma torch head has, on its bearing side, a first cylinder wall with an outer surface and an annular surface and an external diameter D21a, and the other of the plasma torch shaft and the plasma torch head has, on its bearing side, a second cylinder wall with an inner surface and internal diameter D31a, where D31a is > D21a, and nVor similar radial projections and nVer similar radial indentations being provided peripherally on the inner surface, where nVor, nVer is = 0 and nVor + nVer = n = 5, and a similar number of corresponding indentations or projections in engagement with them being provided on the outer surface, the projections and indentations further being arranged such that when the plasma torch shaft is connected to the plasma torch head, the projections and inden¬tations first have to be brought into engagement before the first bearing surface and the second bearing surface come to abut each other, and in the event that n = 5, the sum of two adjacent angles at the centre by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the five angles at the centre are different in size, or in the event that n > 5, the sum of two adjacent angles at the centre by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre are different in size or at least two of the n > 5 angles at the centre are equal in size, and then in each case the sum of the respective angles oc¬curring twice at the centre and the adjacent angles at the centre on either side thereof is The plasma torch can be a plasma cutting or welding torch.
In the plasma torch head, it can be provided that the sum of two adjacent angles at the centre is = 170°. In this way, an even more stable abutment of the annular sur¬face and projections in the joint position is achieved.
According to a particular embodiment of the invention n = 5 and the sum of two ad¬jacent angles at the centre is not repeated.
According to a further particular embodiment, the plasma torch head contains four fluid passageways.
The at least one fluid passage is advantageously provided with a connector.
The current conductor is conveniently likewise provided with a connector.
In addition, it can be provided that indentations are rectangular grooves. It goes without saying that the grooves can also be any other shape, such as arcuate, triangu¬lar etc.
According to a further particular embodiment, nVer is = 5.
Alternatively, it is also conceivable that nVor is = 5.
The dependent claims concerning the plasma torch shaft relate to advantageous fur¬ther improvements thereof.
On the inner surface of the cylinder wall, a peripheral chamfer extending radially outwards can, for example, be provided towards the bearing side before the projec¬tions. This makes it easier to join the parts together, because a larger diameter is available at the beginning of the joining action.
The dependent claims concerning the plasma torch relate to advantageous further improvements thereof.
One particular embodiment of the plasma torch, for example, is characterised by the fact that the plasma torch head has the first cylinder wall and the plasma torch shaft has the second cylinder wall.
The invention is based on the surprising finding that the specific number and ar¬rangement of projections and corresponding indentations makes it possible to join the plasma torch head and plasma torch shaft together quickly and easily, without jamming. It is merely necessary for the annular surface to be simply brought to rest against the projections, i.e. to be placed in a joining position, and then to be turned relative to the projections until the joint position is reached, in which, when an axial force is applied, the projections and indentations engage with one another. This is particularly advantageous in situations in which the plasma torches are clamped in and are not visually accessible. The rapid exchange of the plasma torch head can be carried out blind, as it were.
In addition, the invention offers a quick-change connection between the plasma torch head and the plasma torch shaft with protection against twisting, a small tole¬rance between the axes of the plasma torch head and the plasma torch shaft and a high degree of centralisation.
The fluid passageways both for the gas, and also as plasma and secondary gas, and for the coolant, can also be used for transporting current.
Further features and advantages of the invention will become clear from the claims the following description, in which two embodiments of the invention are illustrated in detail with reference to the schematic drawings. There,
Figure 1 shows a side view of a front part of a plasma cutting torch before the plasma cutting torch head and plasma cutting torch shaft are joined together, in accordance with a particular em¬bodiment of the present invention, partially in section;
Figure 2 shows a side view of the front part of the plasma cutting torch while the plasma cutting torch head and plasma cutting torch shaft are being joined together in the joint position, partially in section;
Figure 3a shows a plan view of the plasma cutting torch shaft from the bearing side;
Figure 3b shows a plan view of the plasma cutting torch head from the bearing side;
Figure 4a shows a sectional view of the plasma cutting torch head and shaft in the joining position in the region of the indentations and projections;
Figure 4b shows a sectional view of the plasma cutting torch head and shaft in the joint position in the region of the indentations and projections;
Figure 5 shows a side view of the front part of the plasma cutting torch after the plasma cutting torch head and plasma cutting torch shaft have been joined together, partially in section;
Figure 6 shows a section of Figure 2;
Figures 6a to 6f show a detail from Figure 6 in various embodiments;
Figure 7 shows various embodiments of indentations and/or projec¬tions;
Figure 8 shows details from Figure 4b; and
Figure 9 shows a view similar to Figure 4a.
As can be seen from Figures 1 and 2, a plasma cutting torch 1 comprises a plasma cutting torch head 2 and a plasma cutting torch shaft 3. As can be seen with refer¬ence to Figures 3a and 3b and also Figure 5, the plasma cutting torch head 2 has a first bearing surface (not shown), a connector 241 for water feed, a connector 242 for water return, a connector 243 for plasma gas, a connector 244 for secondary gas and a connector 245 for pilot current. The connectors 241 to 245 are provided with holes (not indicated) for the passage of gas or fluids. The plasma cutting torch shaft 3 has a second bearing surface (not shown), a socket 341 for water return, a socket 342 for water feed, a socket 343 for plasma gas, a socket 344 for secondary gas and a socket 345 for pilot current.
The connectors 241 to 245 and the sockets 341 to 345 form a quick-change inter¬face. It goes without saying that, the connectors or some of them can alternatively be disposed on the plasma cutting torch shaft and the sockets on the plasma cutting torch head. The fluid passageways and current lines in the plasma cutting torch head 2 and in the plasma cutting torch shaft 3, which are needed for supply purposes are not illustrated in detail .
The plasma cutting torch head 2 has a first cylinder wall 21 on its bearing side with an outer surface 21a and an annular surface 22 and an external diameter D21a. The plasma cutting torch shaft 3 has a second cylinder wall 31 on its bearing side with an inner surface 31a and an internal diameter D31a, where D31a is > D21a. In order to insert the plasma cutting torch head 2 into the plasma cutting torch shaft 3, the latter has considerable play S in the joining position (see Figures 6a, 6d, 6e and 6f).
As can be seen from Figures 3a and 3b, the plasma cutting torch shaft 3 has five similar rectangular lugs 331, 332, 333, 334 and 335 peripherally on its inner surface 31a, and the plasma cutting torch head 2 has five similar correspondingly designed and arranged rectangular grooves 231, 232, 233, 234 and 235 on its outer surface 21a. The lugs 331 to 335 and grooves 231 to 235 are arranged in the axial direction in such a way that when the plasma cutting torch shaft 3 is joined to the plasma cut¬ting torch head 2, the grooves and lugs are first engaged before the first bearing sur¬face and the second bearing surface come into abutment.
When the plasma cutting torch head 2 is inserted into the plasma cutting torch shaft 3, the annular surface 22 of the plasma cutting torch head 2 usually encounters the lugs 331 to 335 (see Figure 4a). The plasma cutting torch head 2 and the plasma cut¬ting torch shaft 3 are thus located in the joining position.
Since the sum of two adjacent angles at the centre of the angles at the centre ?, ?, ?, ? and ? (see Figure 8) at which the grooves 231 to 235 are arranged is not = 180°, and the five angles at the centre are different in size, the lugs 331 to 335 together with the annular surface 22 of the plasma cutting torch head interrupted by the grooves 231 to 235 form a virtual closed surface A relative to one another in any position except the joint position (see Figure 4b). With the exception of the joint position, the grooves 231 to 235 are always arranged such that the lugs resting on the annular surface 22 of the plasma cutting torch head 2 (in Figure 4a the lugs 331, 333, 334 and 335) form a quadrangle with the area A, in which the centre axis M of the plasma cutting torch 1 is located (see Figure 4a).
If the additional condition is not met that the sum of two adjacent angles at the cen¬tre of the angles at the centre ?, ?, ?, ? and ? is repeated, only a triangular area A can be formed, as is shown in Figure 9.
Because of the fact that the centre axis M of the plasma cutting torch 1 is located in the area A, the plasma cutting torch shaft 3 and the plasma cutting torch head 2 can be twisted in any direction relative to one another until the joint position is reached. Once the joint position is reached, the plasma cutting torch head 2 slides into the plasma cutting torch shaft 3 under the effect of an axial force, and the two can be in¬serted into one another (see Figures 2, 4b and 5).
By turning a clamping sleeve 25, a further axial force is exerted on the interface via the internal threads 251 of the clamping sleeve and the external threads 35 of the plasma cutting torch shaft 3, until the final joint position is reached (see Figure 5). There, the diameter of the plasma cutting torch shaft is reduced from D31a to D31b, as a result of which the play S is reduced or even eliminated completely and the cen¬tricity is increased. This can of course also be achieved by other mechanisms, such as a bayonet fitting or some other tightening means.
The grooves 231 to 235 are usually larger than the lugs 331 to 335, since it would not otherwise be possible to join them together. The dimension B stands for the cen¬tral width of the grooves and lugs and is calculated (see Figures 3a and 3b) as fol¬lows
.
The similar design of the grooves and lugs means that the production effort is reduc¬ed compared to an embodiment with different lugs and thus grooves, in which three grooves and lugs would be sufficient. It is then possible to work with a single tool.
To simplify the joining process, the inner surface 31a can be designed differently. It can have greater play S with a cylindrical shape (Figure 6a), an angle F (Figure 6b) a radius (Figure 6c) or a combination of the individual elements (Figures 6d, 6e and 6f). It is sufficient for the grooves and lugs to be substantially similar in shape and size. It is only necessary for them to be designed such that the condition with the polygon, such as a triangle or quadrangle for example, are met.
The dimensions may look as follows, for example:
The central diameter D of the first cylinder wall and the second cylinder wall is cal¬culated as follows (see Figure 1):
.
D: 25 to 100mm
F: 15 to 60°

S: 0.2 to 0.7mm
R: 1 to 5mm.
In Figure 8 the parameters look as follows:
? = 75°
? = 70°
? = 90°
? = 65°
? = 60°.
In addition, the spaces a, b, c, d and e between the lugs/grooves are shown in Figure 8. These are the spaces between the axes of symmetry of the lugs and grooves 231 to 235 on the central diameter D. They are calculated according to the formula:
in mm
in mm
etc.
In Figure 9, the angles are selected as follows:
? = 60°
? = 95°
? = 80°
? = 75°
? = 50°.
? + ? = ? + ?
60° + 95° = 80° + 75° = 155°.
Consequently, the sum of two adjacent angles at the centre, namely of ? and ? and of ? and ? is repeated.
Figure 7 shows examples of possible designs of pairs of lugs 331 and grooves 231. The lugs could, however, also be used as grooves and the grooves as lugs.
The features of the invention disclosed in the present description, in the drawings and in the claims can be essential to implementing the invention in its various em¬bodiments both individually and in any combinations.

Claims
1. A plasma torch head (2), comprising at least one fluid passage, an electrode, a nozzle, a current conductor and a bearing surface on a bearing side, characterised by the fact that
on its bearing side, it has a cylinder wall (21) with an outer surface (21a) and an annular surface (22), where nVer similar radial indentations and nVor similar radial projections are provided peripherally on the outer surface (21a), where nVer, nVor are = 0 and nVer + nVor is = 5, and
in the event that n = 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180°, and the five angles at the centre (?, ?, ?, ?, ?) are different in size,
or
in the event that n > 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre (?, ?, ?, ?, ?) are different in size or at least two of the n > 5 angles at the centre (?, ?, ?, ?, ?) are equal in size, and then in each case the sum of the respective angles at the centre (? or ? or ? or ? or ?) occur¬ring twice and the adjacent angles at the centre on either side thereof (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is 2. The plasma torch head (2) as claimed in claim 1, characterised by the fact that the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is = 170°.
3. The plasma torch head (2) as claimed in either of claims 1 or 2, characterised by the fact that n = 5 and the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is not repeated.
4. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that it includes four fluid passageways.
5. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that the at least one fluid passage is provided with a connector (241, 242, 243, 244).
6. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that the current conductor is provided with a connector (245).
7. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that the indentations are rectangular grooves (231, 232, 233, 234, 235).
8. The plasma torch head (2) as claimed in any of the preceding claims, characteris¬ed by the fact that nVer is = 5.
9. The plasma torch head (2) as claimed in any of claims 1 to 7, characterised by the fact that nVor is = 5.
10. A plasma torch shaft (3), comprising at least one feed line for a gas, a current supply line, at least one fluid passage, a current conductor and a bearing surface on a bearing side,
characterised in that
on its bearing side, it has a cylinder wall (31) with an inner surface (31a), where nVor similar radial projections and nVer similar radial indentations are provided peripherally on the inner surface (31a), where nVor, nVer are = 0 and nVor + nVer is = 5, and
in the event that n = 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180°, and the five angles at the centre (?,?, ?, ?, ?) are different in size,
or
in the event that n > 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre (?, ?, ?, ?, ?) are different in size or at least two of the n > 5 angles at the centre (?, ?, ?, ?, ?) are equal in size, and then in each case the sum of the respective angles at the centre (? or ? or ? or ? or ?) occur¬ring twice and the adjacent angles at the centre on either side thereof (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is 11. The plasma torch shaft (3) as claimed in claim 10, characterised by the fact that the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is = 170°.
12. The plasma torch shaft (3) as claimed in either of claims 10 or 11, characterised by the fact that n = 5 and the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ?) is not repeated.
13. The plasma torch shaft (3) as claimed in any of claims 10 to 12, characterised by the fact that, in addition, a feed line for secondary gas is provided and it includes four fluid passageways.
14. The plasma torch shaft (3) as claimed in any claims 10 to 13, characterised by the fact that the at least one fluid passage is provided with a socket (341, 342, 343, 344).
15. The plasma torch shaft (3) as claimed in any claims 10 to 14, characterised by the fact that the current conductor is provided with a socket (345).
16. The plasma torch shaft (3) as claimed in any claims 10 to 15, characterised by the fact that the projections are rectangular lugs (331, 332, 333, 334, 335).
17. The plasma torch shaft (3) as claimed in any claims 10 to 16, characterised by the fact that a peripheral chamfer extending radially outwards is provided on the inner surface (31a) of the cylinder wall (31) towards the bearing side before the projections and/or indentations .
18. The plasma torch shaft (3) as claimed in any of claims 10 to 17, characterised by the fact that nVor is = 5.
19. The plasma torch shaft (3) as claimed in any of claims 10 to 17, characterised by the fact that nVer is = 5.
20. A plasma torch (1), comprising at least one feed line for a gas, an electrode, a nozzle and a current supply line, the plasma torch (1) including a plasma torch shaft (3) which has at least one first fluid passage, a first current conductor and a first bearing surface on a bearing side, and
comprises a plasma torch head (2) which includes at least one second fluid pas¬sage, a second current conductor and a second bearing surface on a bearing side, the first and second bearing surfaces resting axially relative to one another, and the at least one first fluid passage being in fluid connection with the at least one second fluid passage, and the first current conductor being in electric connection with the second current conductor,
characterised by the fact that
one of the plasma torch shaft (3) and the plasma torch head (2) has, on its bear¬ing side, a first cylinder wall (21) with an outer surface (21a) and an annular sur¬face (22) and an external diameter D21a, and the other of the plasma torch shaft (3) and the plasma torch head (2) has, on its bearing side, a second cylinder wall (31) with an inner surface (31a) and an internal diameter D31a, where D31a is > D21a, and nVor similar radial projections and nVer similar radial indentations being provided peripherally on the inner surface (31a), where nVor, nVer is = 0 and nVor + nVer = n = 5, and a similar number of corresponding indentations or pro¬jections in engagement with them being provided on the outer surface (21a), the projections and indentations further being arranged such that when the plasma torch shaft (3) is connected to the plasma torch head (2), the projections and in¬dentations first have to be brought into engagement before the first bearing sur¬face and the second bearing surface come to abut each other, and
in the event that n = 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180°, and the five angles at the centre (?,?, ?, ?, ?) are different in size,
or
in the event that n > 5, the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) by which the projections and indentations or one projection and one indentation are offset from one another is not = 180° and the n > 5 angles at the centre (?, ?, ?, ?, ?) are different in size or at least two of the n > 5 angles at the centre (?, ?, ?, ?, ?) are equal in size, and then in each case the sum of the respective angles at the centre (? or ? or ? or ? or ?) occur¬ring twice and the adjacent angles at the centre on either side thereof (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is 21. The plasma torch shaft (1) as claimed in claim 20, characterised by the fact that the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is = 170°.
22. The plasma torch (1) as claimed in either of claims 20 or 21, characterised by the fact that n = 5 and the sum of two adjacent angles at the centre (? and ? or ? and ? or ? and ? or ? and ? or ? and ?) is not repeated.
23. The plasma torch (1) as claimed in any of claims 20 to 22, characterised by the fact that, in addition, a feed line for secondary gas is provided and the plasma torch shaft (3) includes four first fluid passageways and the plasma torch head (2) includes four second fluid passageways.
24. The plasma torch (1) as claimed in any of claims 20 to 23, characterised by the fact that the coolant is water.
25. The plasma torch (1) as claimed in any claims 20 to 24, characterised by the fact that the at least one first fluid passage is provided with a socket (341, 342, 343, 344).
26. The plasma torch (1) as claimed in any claims 20 to 25, characterised by the fact that the at least one second fluid passage is provided with a connector (241, 242, 243, 244).
27. The plasma torch (1) as claimed in any claims 20 to 26, characterised by the fact that the first current conductor is provided with a socket (345).
28. The plasma torch (1) as claimed in any claims 20 to 27, characterised by the fact that the second current conductor is provided with a socket (245).
29. The plasma torch (1) as claimed in any claims 20 to 28, characterised by the fact that the plasma torch head (2) has the first cylinder wall (21) and the plasma torch shaft (3) has the second cylinder wall (31).
30. The plasma torch (1) as claimed in any claims 20 to 29, characterised by the fact that the indentations are rectangular grooves (231, 232, 233, 234, 235).
31. The plasma torch (1) as claimed in any claims 20 to 30, characterised by the fact that a peripheral chamfer extending radially outwards is provided on the inner surface (31a) of the second cylinder wall (31) towards the bearing side before the projections and/or indentations .
32. The plasma torch (1) as claimed in any of claims 20 to 31, characterised by the fact that nVor is = 5.
33. The plasma torch (1) as claimed in any of claims 20 to 31, characterised by the fact that nVer is = 5.
34. The plasma torch (1) as claimed in any claims 20 to 33, characterised by the fact that a holding means for holding the plasma torch head and the plasma torch shaft (3) together is provided.
35. The plasma torch (1) as claimed in claim 34, characterised by the fact that the holding means is a clamping sleeve.

Abstract
A plasma torch head, a plasma torch shaft and a plasma torch for providing a quick and simple possibility of changing the plasma torch head are described.

Documents:

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Patent Number

270952

Indian Patent Application Number

264/MUMNP/2009

PG Journal Number

05/2016

Publication Date

29-Jan-2016

Grant Date

28-Jan-2016

Date of Filing

04-Feb-2009

Name of Patentee

KJELLBERG FINSTERWALDE PLASMA UND MASCHINEN GMBH

Applicant Address

Leipziger Straße 82 03238 Finsterwalde Germany

Inventors:

#	Inventor's Name	Inventor's Address
1	Ralf-Peter Reinke	Käthe-Kollwitz- Straße 1a 03238 Finsterwalde Germany
2	Timo Grundke	Schacksdorfer Straße 27 03238 Finsterwalde Germany
3	Frank Laurisch	Kriemhildstraße 2a 03238 Finsterwalde Germany
4	Volker Krink	Friedastraße 8 03238 Finsterwalde Germany

PCT International Classification Number

H05H 1/34

PCT International Application Number

PCT/DE2007/001430

PCT International Filing date

2007-08-13

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	102006038134.3	2006-08-16	Germany