Abstract:
A system for the thermal processing of workpieces. In this respect, workpieces can be processed by a plasma jet or by a laser beam. The thermal processing of workpieces is done more flexibly and also less expensive in this respect. A laser processing head or a plasma processing head can be connected by a single shaft element.

Description:
This is a national stage of PCT/DE09/001,540 filed Oct. 23, 2009 and published in German, which claims the priority of German number 10 2008 056 278.5 filed Oct. 25, 2008, hereby incorporated by reference. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The invention relates to a system for the thermal processing of workpieces. In this respect, workpieces can be processed by a plasma jet or by a laser beam. The invention can preferably be used for separating processing, that is, for cutting, but also for welding workpieces. 
     BACKGROUND OF THE INVENTION 
     The processing with plasma is very productive and metallic workpieces can, for example, be economically separated in the thickness range 1 to 60 mm for construction steels and 1 to 160 mm for aluminum and CrNi steels. In this respect, a plasma is directed onto a workpiece to be processed by an arc which generates a highly heated and electrically conductive gas and restricted by a nozzle. The material is melted by means of the thermal and kinetic energy and is driven out of the kerf which is formed. The layer quality has been able to be considerably improved in the very recent past. Only the taking into account of filigree contours, that is, the taking into account of large changes in the feed axis direction with small diameters, presents problems. Holes with radii smaller than 5 mm or which are smaller than 1.5 times the thickness of a workpiece, can thus not be realized in high quality when cutting with plasma. 
     A processing with laser radiation achieves a better cutting quality when cutting in the lower workpiece thickness range (&lt;10 mm). Smaller kerfs and sharp edges can be formed with very small radii. With larger workpiece thicknesses, the productivity is much smaller and a processing is no longer possible from a thickness of some centimeters onward. 
     When cutting, a processing using plasma is less expensive, faster and frequently has a higher quality from workpiece thicknesses of 5 mm upward. 
     With the introduction of fiber lasers into production, wherein the laser radiation is guided via optical waveguides, the beam guiding has been substantially simplified. 
     Both the plasma technique and the laser technique can each be used in automated form in conjunction with CNC controlled guide systems, e.g. coordinate guide systems or industrial robots. In this respect, an increased plant engineering effort and/or a further clamping of workpieces in a respectively different plant is/are necessary for the processing if both processing methods should be carried out on one workpiece. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the invention to make possible the thermal processing of workpieces more flexibly and also less expensive in this respect. 
     Technical elements can be made use of in the invention which are known per se, but which will be somewhat modified. Plasma processing heads and laser processing heads can thus be used whose basic structure corresponds to that previously used. In this respect, an adaptation, in particular for laser processing heads, can also take into account whether they should be used for welding or cutting since a supply of cutting gas/processing gas is necessary for the cutting which is required through a nozzle onto the workpiece for driving molten material out of the kerf. 
     Process gas is, however, also required for operating a plasma processing head. A common access of both components to a jointly usable gas supply can thereby be utilized in the invention. 
     A system in accordance with the invention is designed in this respect so that a laser processing head and a plasma processing head can be connected by a single shaft element. In this respect, at least one feed for the electric current to an electrode in the plasma processing head, an optical waveguide for laser radiation and a feed for process gas are preferably present in the shaft element. They can in each case be in communication with one another or be connected with one another by complementary connections or elements, which are present at the plasma processing head and at the laser processing head, in the state fastened to the shaft element. In this respect, the feeds are connected to a supply for electric current or a supply for process gas and the optical waveguide is connected to a laser light source. 
     The shaft element can be fastened to a guide system such as is known from the prior art. It is designed so that a plasma processing head and a laser processing head can be fastened thereto, but that an exchange of the different processing heads is possible simply and fast. This can be achieved with suitable quick-change closures. A replacement can thus be realized simply and fast on a change in the processing or when wear has occurred. In addition to the common guide system, a single workpiece clamping device, however, other contact components can also be used such as in particular a gas supply or also an additional cooling system for both processing kinds together which are present or may be present at the system in accordance with the invention. In this respect, a cooling system can be designed so that an additional cooling only takes place on a processing using plasma or using laser radiation. This will preferably be the processing using plasma. In this respect, the shaft element and the different processing heads can be designed accordingly so that a coolant can only flow into, and back out of one of the two different processing heads again. 
     A laser light source with smaller power is required since it is also possible to work with plasma when higher powers are required. 
     The most varied materials and workpieces having different thicknesses can be processed using the invention. The costs for plant engineering can be reduced and the productivity increased since the advantages of the two different processing methods can be utilized. 
     There is also the possibility of designing the process gas supply so that a secondary gas can also be supplied. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The invention will be explained in more detail in the following with reference to examples. 
    
    
     
       There are shown: 
         FIG. 1  in schematic form, the structure of an example of a system in accordance with the invention; 
         FIG. 2  options for the design of a shaft element, of a plasma processing head and of a laser processing head without cooling; 
         FIG. 3  options for the design of a shaft element, of a plasma processing head and of a laser processing head with cooling; 
         FIG. 4  in schematic form, the structure of a further example of a system in accordance with the invention; 
         FIG. 5  in schematic form, the structure of a further example of a system in accordance with the invention; 
         FIG. 6  in schematic form, the structure of a further example of a system in accordance with the invention; 
         FIG. 7  in schematic form, the structure of a further example of a system in accordance with the invention; and 
         FIG. 8  in schematic form, the structure of a further example of a system in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A simple example of a system in accordance with the invention without additional cooling will be illustrated by  FIG. 1  in schematic form. 
     In this respect, a plasma source  10 . 1  and a fiber laser as a laser light source  10 . 2  are connected to an electric power supply (mains). A shaft element  20  is connected via feeds  30 . 1  to a plasma source  10 . 1  via which an electrode, not shown, present in a plasma processing head  21  can be supplied with electric power. Emitted laser radiation reaches the shaft element  20  via an optical waveguide  30 . 2 . Process gas is supplied by a gas control  40  via the line  30 . 3 . A common hose or line packet  30  can be formed with the lines  30 . 1 ,  30 . 2  and  30 . 3 . 
     A plasma processing head  21  or a laser processing head  22  can selectively be fastened to the shaft element  20 . In this respect, in a system designed in this manner, the process gas control and the process gas management can be used jointly in both processes. Only the respective required process gas pressures and process gas volume flows have to be taken into account. 
     Possible embodiments of the shaft element  20 , of the plasma processing head  21  and of the laser processing head  22  such as can be used in a system in accordance with  FIG. 1  or a system without cooling should be illustrated by  FIG. 2 . 
     In this respect, the upper representation reproduces the three components  20 ,  21  and  22 . In the middle, a view is shown, marked by Z, from below and from the side respectively of the shaft element  20  to which the plasma processing head  21  and the laser processing head  22  can be fastened. 
     The optical waveguide  20 . 2  for the laser radiation is guided through the middle longitudinal axle. In addition, the feed  20 . 1  for electric current for the plasma operation and the feed  20 . 3  of process gas through the shaft element  20  to the processing heads  21  and  22  are formed. 
     Views from the side of the two processing heads  21  and  22 , at which side they can be connected to the shaft element  20 , are shown at the bottom left and bottom right. In this respect, the optical waveguide  22 . 2 , and the feeds  21 . 1  and  21 . 3  are arranged and aligned so that a connection can be ensured and the respective media can be conducted through them to the respective processing head  21  or  22 . 
     The representation of  FIG. 3  corresponds in substantial points to  FIG. 2 . However, modified processing heads  21  and  22  and a modified shaft element  20  are shown such as can be used in the systems shown in the following with respect to  FIGS. 6 to 8  since here an additional cooling is provided. 
     The same elements are provided with the same reference numerals. In this example, there are present in the shaft element  20  shown in the middle, a feed  20 . 4  and a return line  20 . 5  for a coolant can be guided through the shaft element  20  into the respective processing head  21  or  22  and back again to a cooling system  50  which can be preferably designed as a return cooling system. The wear in operation can be reduced by a cooling. 
     The feed  20 . 4  can open into the coolant line  21 . 4  of the plasma processing head  21  or into the coolant line  22 . 4  of the laser processing head  22  and the return  20 . 5  into the coolant lines  21 . 5  or  22 . 5  of the respective processing head  21  or  22  respectively fastened to the shaft element  20 . 
     There is also the possibility of forming and associating a feed  20 . 1 ,  21 . 1  for electric current so that it can be conducted within a passage or a feed or return line  20 . 4 ,  21 . 4 ,  20 . 5  or  21 . 5  for coolant and can be cooled in so doing. The cross-section of a used electric conductor can be reduced by a cooling over comparable electric currents flowing through it without cooling. 
     The further embodiments of the two processing heads  21  and  22  are not shown. They can be designed as usual. That is, the electrodes and nozzles can be arranged or present accordingly at the plasma processing head  21 . 
     At the laser processing head  22 , an optical element focusing on or forming the laser beam directed onto the workpiece can be present. Said laser processing head can also be provided with a cutting nozzle if a cutting is intended to be carried out on workpieces. 
     A system in accordance with the invention can also be further developed so that what type of processing head  21  or  22  is fastened to the shaft element  20  at the time can be detected automatically so that this can be taken into account for the control or regulation of the processing process and incorrect operations can be avoided. For this purpose, a sensitive element can be present which is arranged at the shaft element  20  and/or at the different processing heads  21  or  22 . This is connected for the identification to an electronic control so that an automated, safe operation can be carried out in accordance with the respective processing procedure to be carried out. A sensitive element can e.g. be a switch contact. In a simple embodiment, a switchover of a common power source  10  of the plasma source  10 . 1  to the laser light source  10 . 2 , or vice versa, can be carried out in this respect. 
     The example shown in  FIG. 4  only differs from the example of  FIG. 1  in that the plasma source  10 . 1  and the laser light source  10 . 2  are jointly connected to an electric power source  10  by which the power can be influenced. In the example shown in  FIG. 5 , the plasma source  10 . 1 , the laser light source  10 . 2  and the energy source  10  are formed as an integrated unit. The use of a common power source  10  or energy supply is likewise inexpensive and therefore advantageous. 
     The examples shown in  FIGS. 6 to 8  have an additional cooling  50  with the feed line  30 . 4  and the return line  30 . 5  for a coolant to the shaft element  20  with the respective processing head  21  and  22  and from there back to the cooling  50 . Except for the additional cooling  50  with the lines  30 . 4  and  30 . 5 , the example in accordance with  FIG. 6  corresponds to the example shown in  FIG. 4 . This applies analogously to the example of  FIG. 1  for the example shown in  FIG. 7  and to the example of  FIG. 5  without cooling  50  for the example of  FIG. 8 .