Abstract:
An assembly device for assembling and disassembling a rotor of a turbomachine with rotor disks that are clamped together by at least one tie rod is provided. The assembly device includes a turning block that is secured to a base and a securing device that secures the rotor against tilting. The rotor is arranged in a transversal manner in relation to a horizontal plane of the base and pivotably mounted on the turning block. The securing device is fixed to the base by several supports and the turning block is arranged inside the surface of the base that is clamped by the supports. Large forces and torque coming from the rotor that is arranged in a perpendicular manner are guided from the securing device to the base.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is the US National Stage of International Application No. PCT/EP2008/053993 filed Apr. 3, 2008, and claims the benefit thereof. The International Application claims the benefits of European Patent Application No. 07007681.5 EP filed Apr. 16, 2007; both of the applications are incorporated by reference herein in their entirety. 
     FIELD OF INVENTION 
     The invention relates to an assembly apparatus for assembling and dismantling a turbomachine rotor composed of rotor disks, which rotor disks are braced with respect to one another by means of at least one tie rod, said assembly apparatus comprising a turning block fastened on a foundation, and a securing device which secures a rotor mounted pivotably on the turning block and set up transversely with respect to a horizontal plane of the foundation, against tipping over. 
     BACKGROUND OF INVENTION 
     Gas turbines and their construction are generally known. The rotors of gas turbines may in this case be constructed and assembled in various ways. One rotor variant comprises a multiplicity of elements which lie one against the other and which are braced via a tie rod extending centrally through the elements. These elements are, on the one hand, rotor disks and, on the other hand, tubular sections, what are known as hollow shafts, which may bear against the rotor disks. The rotor disks and hollow shafts are in each case braced by means of screw nuts screwed onto the end faces of the tie rod, the screw nut provided on the compressor side often being designed as a hollow shaft. As a rule, the rotor disks bearing one against the other over a large area on their end faces carry the moving blades of the turbine and of the compressor on their outer circumferences. Instead of one central tie rod, it is also known to use a plurality of decentral eccentric tie rods. 
     In order to assemble and dismantle a multipart rotor of this type, an assembly tool is known which comprises essentially two bearing blocks. The two bearing blocks are set up at a distance from one another and the rotor is deposited on them. One of the two bearing blocks, what is known as the turning block, is in this case equipped with a joint which is arranged between the foot and the bearing surface and it is fastened to one end of the rotor. The rotor is therefore placed such that its, for example, compressor-side end can be fastened directly to the joint of the turning block. The other bearing block then supports the rotor on the turbine side. The joint fastened to the turning block serves for transferring the rotor out of the horizontal position into a position perpendicular thereto. For this purpose, a suspension nut is screwed onto the tie rod at the turbine-side end of the rotor. A cable of a crane is fastened to the suspension nut by means of a shackle. While the crane is lifting the turbine-side end of the rotor, the compressor-side end rotates about the center of rotation of the joint. The lifting operation is concluded when the rotor has reached an approximately vertical position. It is then secured against tipping over by means of a securing device which is also provided on the turning block. As a rule, this securing device comprises a blocking bolt which is provided, above the joint, on the turning block and which blocks the backward movement of the rotor out of the vertical position. The suspension nut is subsequently demounted, after which the actual work on the vertically set-up rotor (or tie rod) can then be carried out. 
     To assemble the rotor, first the tie rod is set up vertically, and subsequently the individual rotor disks are slipped onto the tie rod in succession from above by means of a crane. A turbine-side rotor nut is then screwed on. When a fully mounted rotor is being demounted, after it has been set up vertically, the rotor nut arranged on the turbine side is removed, after which the individual rotor disks can be extracted from the tie rod. The rotor then comprises essentially only the tie rod. 
     A similar setting-up apparatus with a turning block is known from Gelman Laid-open publication 24 26 231. A first stop is fastened centrally, under the turning block, to the foundation. In contrast to the abovementioned apparatus, it is not the end of the rotor which is fastened to the turning block, but, instead, a rotor point at a distance from the end. When the longer rotor section is being lifted, the shorter rotor section then pivots toward the foundation. The coupling flange arranged on the shorter rotor section bears against the first stop after vertical set-up, after which a second stop is then adapted on the other side of the flange and is fixedly connected via screws to the first stop in order to secure the rotor against tipping over. 
     SUMMARY OF INVENTION 
     An object of the present invention is to specify a novel assembly apparatus for assembling and dismantling a turbomachine rotor composed of rotor disks, by means of which assembly apparatus an earthquake-proof support of the vertically set up rotor is achieved. 
     The object is achieved by an assembly apparatus as claimed in the claims. 
     The invention proceeds from the recognition that an earthquake-proof assembly apparatus can be obtained when the turning block and the securing device for preventing tipping over can be fastened separately from one another to the foundation. Hitherto, the securing device has been provided either on the turning block or comparatively near to the pivoting point. On account of this arrangement, only a comparatively weak securing of the vertically standing rotor was possible, which, in zones where minor earthquakes occur comparatively often, for example in California or in New Zealand, could no longer ensure a reliable support of the rotor set up vertically for assembly or disassembly. In light of this requirement, according to the invention, there is provision for using stays which carry the securing device and are fastened to the foundation and which span a foundation surface in which the turning block is arranged. The securing device is, as it were, jacked up via a scaffold formed from stays. The turning block according to the invention then absorbs only the weight forces of the vertically set-up rotor and conducts these further on into the foundation. A torque load upon the turning block fastening, as in the prior art, is thus avoided. Said turning block can consequently have a comparatively simple design. The forces acting from the rotor laterally upon the securing device can be conducted into the foundation, away from the turning block, via the stays fastened in the vicinity of the turning block. 
     Further, the distance between the rotor support point projected on the foundation and the likewise projected points of the lateral rotor support preventing the rotor from tipping over about the axis of rotation of the joint is increased significantly due to the use of preferably four stays. In other words, the distance, determined over the vertical height of the foundation, between the central fastening point of the rotor to the turning block and the point of its lateral support is increased significantly, with the result that the lateral supporting forces to be absorbed by the securing device and to be diverted by the stays can be kept comparatively low. 
     Moreover, owing to the design of the centrally arranged turning block and of the stays surrounding this in a punctiform manner on the foundation, an assembly apparatus of lightweight build can be made possible. 
     Owing to the separation of the support of the rotor in the turning block and the securing of the rotor against tipping over by means of the securing device, pronounced laterally acting forces and moments emanating from the rotor and occuring, for example, during a comparatively weak earthquake can now be absorbed by the securing device and diverted into the foundation, without the vertically set-up rotor in this case threatening to tip over or actually tipping over. The forces for lateral support are in this case absorbed at a height, with respect to the foundation plane, which is substantially greater than the height of the axis of rotation of the joint of the turning block to which the rotor is fastened. 
     Thus, by virtue of the invention, an especially safe and reliable assembly apparatus for assembling and dismantling a turbomachine rotor composed of rotor disks can be specified. 
     The securing device in this case comprises a supporting surface against which the rotor bears. The supporting surface is preferably slightly displaceable. Particularly when the rotor is to be oriented into the vertical position, the forces acting from the rotor on the securing device transversely to the normal force are comparatively low, so that the securing device can have correspondingly adapted dimensioning. Furthermore, the vertically standing rotor makes it possible to slip rotor disks onto or off the tie rod in a particularly simple way. Insofar as the supporting surface against which the rotor comes to bear can be displaced in a plane approximately parallel to the horizontal plane, the already approximately vertically standing rotor can be oriented such that only balancing forces have to be absorbed by the securing device and its scaffold. The entire weight force of the rotor is in this case then carried by the turning block and conducted into the foundation. 
     Advantageous refinements are specified in the dependent claims. 
     In an expedient refinement, the securing device is arranged above the foundation via four stays arranged in a rectangle on the foundation. 
     The securing device has to absorb only comparatively low forces if it comprises at least one supporting surface by means of which the rotor set up transversely with respect to the horizontal plane can be supported laterally, and in which the vertical distance between a joint of the turning block and the supporting surface arranged above it is 2 m to 3 m. 
     In an advantageous refinement of the securing device, this has above the foundation a platform or work stage jacked up on a plurality of stays and struts. The platform serves, for example, as a work platform for fitters who carry out the orientation of the rotor into the vertical position. Then especially, it is advantageous if the supporting surface is provided at the height of the platform, for example in the bottom of the latter. The one or more supporting surfaces which are provided on horizontally displaceable elements can then be connected to the platform via the screw connections or the hydraulic cylinders. 
     According to a further advantageous refinement, the turning block is designed in such a way that it conducts the weight force of the rotor further on into the foundation over a circular area. A punctiform, possibly inadmissibly high weight load upon the foundation can thereby largely be avoided. Instead, the weight load of the rotor is distributed by the turning block to the circular connecting surface of the turning block and foundation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained by means of a drawing in which, diagrammatically and not true to scale: 
         FIG. 1  shows the assembly apparatus for assembling and dismantling a rotor, with the rotor arranged (horizontally) parallel to the horizontal plane, 
         FIG. 2  shows the assembly apparatus according to  FIG. 1 , with the rotor set up vertically, 
         FIG. 3  shows a top view of the securing device, with the receptacle open, and 
         FIG. 4  shows a top view of the securing device, with the rotor introduced. 
     
    
    
     Identical components are given the same reference symbols in the figures. 
     DETAILED DESCRIPTION OF INVENTION 
       FIG. 1  illustrates a rotor  13  deposited on two bearing blocks  11 , of a heavy stationary gas turbine. The rotor  13  comprises a tie rod  15  which extends centrally through a multiplicity of turbine disks  17  and compressor disks  19 . In the example illustrated, the compressor-side end of the rotor  13  is illustrated on the left. The turbine disks  17  and the compressor disks  19  are rotor disks  21  and carry at their outer ends moving blades which can be exposed to a compressible flow medium of the gas turbine. 
     For bracing the rotor disks  21 , a front hollow shaft  22  is screwed onto the tie rod  15  on the compressor-side end  33  of the rotor  13 . A screw nut  24  is provided on the turbine side. 
     In order to dismantle the modular rotor  13  of the gas turbine into its individual parts, in addition to the two bearing blocks  11  an assembly apparatus  23  is provided which is arranged at the rotor end. The assembly apparatus  23  comprises a turning block  27  which is fastened on a foundation  29 . The turning block  27  is set up in alignment with the two bearing blocks  11  and in this case has at its tip a joint  31  which is connected to the compressor-side end  33  of the rotor  13 . The rotor  13  is in this case rotatable about an axis of rotation, parallel to the horizontal plane  47 , of the joint  31 . Further more, the joint  31  comprises a rolling-bearing-mounted receptacle for a turntable  37  rotatable about a vertical axis  35 . Moreover, the rotary support point lies on the vertical axis  35 . 
     Mounted at the turbine-side end  39  of the rotor  13  is a suspension nut  41 , to which the cable of a crane can be fastened by means of a shackle. 
     The assembly apparatus  23  comprises, furthermore, a securing device  45  which is designed as a scaffold  43  and which is anchored separately from the turning block  27  in the foundation  29 . 
     The scaffold  43  comprises a platform  49  or work stage jacked up on four vertical stays  64 . For stiffening the scaffold  43 , further struts  65  extending transversely with respect to the stays  64  are provided at each side edge of the scaffold  43  and additionally connect the foundation-side ends of the stays  64  to the platform  49 . 
     So that the rotor  13  can be pivoted into the scaffold  43  and into the securing device  45 , part of the platform  49  and the struts  65  arranged below it can be moved out of the pivoting range of the rotor  13 . The platform  49  and the securing device  45  then have an opened receptacle (cf.  FIG. 3 ). 
     By the turbine-side end  39  of the rotor  13  being raised by means of the crane, the rotor  13  is lifted out of the two bearing blocks  11 , the compressor-side end of the rotor  13  rotating about the axis of rotation of the joint  31 . With the receptacle open, the rotor  13  can then be turned out of its horizontal position ( FIG. 1 ) into the vertical position ( FIG. 2 ), after which it is secured against tipping over by means of the securing device  45 . The receptacle is closed for this purpose. The rotor  13  is then in the position illustrated in  FIG. 2 . 
     The entire weight force of the rotor  13 , which is comparatively heavy when it is used in stationary gas turbines, then exerts a load upon the turning block  27 , whereas the scaffold  43  can prevent the rotor  13  from tipping over by means of comparatively low forces. The least force is required when the rotor  13  is oriented vertically and the axis of symmetry  46  of the rotor  13  coincides with the axis  35  of the turntable  37 . 
     On account of the comparatively long distance between the joint  31  and the lateral support of the rotor  13  at the height of the platform  49 , an especially reliable and, moreover, also earthquake-proof lateral support of the rotor  13  can be afforded. Earthquake-proof means in this context that the acceleration forces upon the rotor  13 , of the order of magnitude of approximately ½ g (1 g=simple gravitational acceleration), which occur with comparatively low intensity during comparatively weak earthquakes can be absorbed by the securing device  45  and be diverted into the foundation  29  via the platform  49  and the struts  65 . 
       FIGS. 3 and 4  show a top view of the platform  49  of the securing device  45 ,  FIG. 3  showing the platform  49  opened in order to receive the rotor  13 , and  FIG. 4  showing the closed platform  49  with the centrally arranged tie rod  15  and front hollow shaft  22  according to the sectional view IV-IV of  FIG. 2 . In the platform  49  of the securing device  45 , a centrally arranged orifice  51  is provided, in which an axial section of the hollow shaft  22  can be introduced. The orifice  51  is surrounded by a segmented ring  53 , the first segment  55  of which comprises a segment arc of approximately 270° and the second segment  57  of which comprises a segment arc of approximately 90°. The second ring segment  57  is pivotable with respect to the first ring segment  55  about an axis of rotation  59 , thus serving for the simple and rapid closing and opening of the ring  53  (cf.  FIG. 4 ). The two segments  55 ,  57  in each case have an inwardly directed supporting surface  61  which in each case can be brought to bear against a portion of the surface area of the rotor  13  or of the tie rod  15 . 
     The ring  53  lies in a plane parallel to the horizontal plane  47 , that is to say parallel to the foundation  29 , and can be displaced, by means of an auxiliary device carrying it, within this plane for the vertical orientation of the rotor  13 . 
     The auxiliary device comprises, for example, a plurality of screw connections  63  fastened to the platform  49 . Each of these screw connections  63  has a screw axis  67  which likewise lies in the plane parallel to the horizontal plane  47 . The screw connections  63  are arranged in a radiating manner when the ring  53  is closed, so that their screw axes  67  meet at a virtual center  66 . Instead of the screw connections  63 , a hydraulic arrangement with a movable piston rod may also be provided in each case, in order, in turn, to support the ring  53  laterally and at the same time to orient the rotor  13  (or else the tie rod  15 ) with respect to the turning block  27  in such a way that the rotor  13  can be displaced from an approximately horizontal orientation to a vertical orientation. 
     Instead of the screw connection or instead of hydraulic cylinders, the ring  53  may also be mounted in a double-nested eccentric, so that the orifice  51  can be oriented, as desired, with respect to the axis  35  of the turning block  27 . 
     The ring  53 , too, is, overall, merely optional. It is also possible, for example, for the lateral support of the rotor  13  to take place directly by means of the screw connections  63  or directly by means of the piston rods of the hydraulic cylinders. The supporting surfaces  61  would then be arranged at the inwardly projecting free ends  69  of the screw connections  63  or at the inwardly projecting free ends of the piston rods of the hydraulic cylinders, which ends would then be capable of being brought to bear directly against the surface area of the rotor  13 . 
     So that the rotor  13  can be pivoted into the orifice  51  when its turbine-side  39  is being raised, the ring  53  and the platform  49  must be opened beforehand. For this purpose, there is provision for the second segment  57  of the ring  53  to be pivotable about the axis of rotation  59  according to the arrow  60 , from a closed position into an open position (illustrated). In the same way, the struts  65 , illustrated at the bottom in  FIG. 3 , and the railing  70  of the work stage are swung away from the platform  49  according to the arrow  62 , so that, overall, the receptacle is opened. 
       FIG. 4  shows a top view of the securing device  45 , with the ring  53  closed virtually completely. The ring  53  surrounds the hollow shaft  22 , so that the supporting surfaces  61  bear against the surface area of the hollow shaft  22 . The ring  53  is displaceable in the plane parallel to the foundation  29  via the individual screw connections  63 , so that the center of the ring  53  and therefore the center of the tie rod  15  can be displaced slightly with respect to the turning block  27  and therefore with respect to the central rotor support point, in order to bring the rotor  13  into a vertical orientation. 
     Overall, owing to the structural separation of the turning block and securing device, the latter can absorb higher forces and moments emanating from the rotor and conduct them further into the foundation than a securing device which is attached directly to the turning block. Pronounced forces may occur, for example, during comparatively minor earthquakes, and therefore the apparatus according to the invention to a certain extent fulfils earthquake requirements. Moreover, the scaffold may also serve as a work platform, so that the orientation of the rotor into a vertical position can be carried out substantially more simply by fitters.