Abstract:
A lathe ( 1 ) in which the work piece ( 16 ) to be lathed with a tool ( 18 ) is clamped with the longitudinal axis of the work piece parallel to the rotational axis ( 29 ) of the rotating clamping device ( 15 ) such that the rotational axis ( 29 ) does not intersect the work piece ( 16 ), and between two machining steps of the machining process by lathing, a position of the work piece ( 16 ) in the clamping device ( 15 ) is changed such that surface areas ( 30, 36 ) not previously machined are moved into the working area of the tool ( 18 ).

Description:
BACKGROUND 
     The invention relates to a method for machining by lathing an elongate workpiece having a longitudinal axis, which workpiece is chucked in a fixture and is rotated at a machining speed about an axis of rotation, a turning tool which performs the lathing being fed transversely, in particular radially, with respect to the axis of rotation and/or tangentially, and the cutting speed of lathing resulting from the rotation of the workpiece in relation to the turning tool. 
     The invention relates, further, to a lathe with a fixture driven by a rotary spindle and with a tool carrier capable of being fed transversely, in particular radially, to the axis of rotation of the rotary spindle and/or tangentially and having a turning tool. 
     Such methods and devices for the lathing of workpieces are known in the most diverse possible forms, the workpiece being rotatable about a central axis, the axis of rotation, and the tool being capable of being fed radially or else tangentially. 
     For many workpieces, however, lathing of this kind is unsuitable, for example for turbine blades which have hitherto often been chucked in relation to an axis running approximately through them in the longitudinal direction and also have been moved in relation to this axis, but on which a milling tool engages. 
     Such a method for the machining of turbine blades requires a large number of feed axes for the milling tool, of rotary drives and of mutually adapted drives and controls. In this case, the cutting speed arises from the very high rotational speed of the tool of 8000-12000 rpm, as compared with turning. 
     SUMMARY 
     The object, therefore, is to provide a method of the type initially mentioned, in which a cross-sectional profile deviating from a circular cross section can be produced by means of fewer drives and adjustment axes. 
     To achieve this object, in a method of the type initially mentioned, there is provision whereby the workpiece is chucked with its longitudinal axis parallel to the axis of rotation, but eccentrically and at a radial distance from the axis of rotation, in the fixture, and the turning tool is fed radially from outside transversely with respect to the axis of rotation, the workpiece orbiting about the axis of rotation on an imaginary cylinder, and whereby the orbiting speed corresponds to the rotational speed of the workpiece, and, during an orbiting movement about the central axis of rotation, the workpiece executes a revolution, and always the same outer face of the workpiece points radially outward during machining by cutting. 
     The workpiece can thus orbit about the axis of rotation on an imaginary cylinder, the orbiting speed corresponding to the rotational speed of the workpiece, that is to say, during an orbiting movement of the workpiece about the central axis of rotation or axis of rotation, the latter itself also executes one revolution, so that always the same outer face also points radially outward and can then be machined by cutting by the tool. Since the longitudinal axis of that region of the workpiece which is to be machined in each case does not coincide with the axis of rotation, and therefore, the machining method leads to an interrupted turning process because of eccentric chucking, the entire circumference of the workpiece is not lathed at the machining point, but instead only the outer face of the workpiece revolving along the cylindrical circular path. 
     The invention can therefore manage with fewer feed axes, as compared with the known methods. It is in this case also advantageous that the relative speed between tool and workpiece, required for cutting machining, does not, as in the known methods, arise from the speed of intrinsic rotation of the workpiece about its longitudinal axis, but instead it results from the rotational speed of the workpiece about the axis of rotation and the radial distance of the workpiece from the axis of rotation. It is thus possible even to make contours which, when the workpiece is chucked in a fixture of the known type, would result in a situation where the region to be machined in the workpiece endeavors to overtake the tool on account of the intrinsic rotation of the workpiece about the center of rotation in the case of a contour deviating from the circular shape, and this will lead to the destruction of the workpiece and/or tool. A much larger number of contours are therefore accessible to lathing. 
     In a refinement of the invention, there may be provision whereby, during a revolution of the workpiece, always the same outer face or the same surface region points radially outward. Workpieces can therefore be manufactured in a simple way which have, in the region of the outer face, a curvature with relatively large radius of curvature and, in the surface regions contiguous to this outer face, a curvature with a comparatively small radius of curvature, for example rounded edges or transitional regions. As a result of eccentric chucking at a radial distance from the axis of rotation, the tool can simply be led radially into the outer face for machining and led out of it, and the situation can be avoided where the cutting speed undershoots/overshoots a critical value. 
     Concave and/or convex outer contours of the surface of the workpiece which deviate from a segment of the surface area of a cylinder can be manufactured if, during a revolution of the workpiece, the turning tool is moved to different radial distances from the axis of rotation. In particular, the radial position of the turning tool with respect to the axis of rotation during a chip removal is thus changed in such a way as to give rise on the workpiece to a surface contour which deviates from the configuration of a segment of the surface area of a cylinder, that is to say which does not describe a segment of the surface area of a cylinder. 
     For this purpose, there may be provision whereby the feed movement of the turning tool is executed synchronously with the rotation of the workpiece. It is advantageous in this case that the desired manufacturing size can be generated by means of a plurality of machining operations which succeed one another during the revolutions of the fixture. This is equivalent to an interrupted cut, since the machining of the segment of the surface area of a cylinder takes place, in the case of one workpiece or two workpieces, only in a specific region during a revolution. 
     To manufacture workpieces having a longitudinal direction, there may be provision whereby the turning tool and the workpiece, during lathing, are additionally moved parallel to the axis of rotation in relation to one another. In this case, the turning tool or the workpiece may remain fixed in space together with the fixture or both the turning tool and the workpiece together with the fixture may be moved in relation to one another simultaneously. 
     In order to manufacture more complex profiles or contours which are described, for example, by at least two surfaces which meet at an edge or a rounding, there may be provision whereby, after the lathing of the radially outward-pointing surface regions, the position of the workpiece in the fixture is varied in such a way that hitherto radially inward-pointing surface regions point outward, and whereby the then outwardly-pointing surface regions are lathed. This variation in position may take place, for example, by displacement and/or rotation and/or rechucking. In particular, airfoil or turbine blade profiles can thus be manufactured, in that, first, one side face, that is to say the front side or top side, is machined and, in a subsequent operation, the other side face, that is to say the rear side or underside, is machined. A workpiece with a side face having a concave profile and with a side face having a convex profile can thus be manufactured in one chucking. 
     Alternatively or additionally, there may be provision whereby, to vary its position, the workpiece is moved in the fixture along a path lying in a radial plane, preferably along a path running through the axis of rotation, and/or onto the side lying opposite with respect to the axis of rotation. The workpiece is thus moved into a position on the fixture in which the surface originally pointing inward during the first machining pass and therefore not accessible to turning tools points radially outward and is therefore accessible to turning tools engaging radially from outside and is thus brought into the working range of the latter. 
     There may also be provision whereby, to vary its position, the workpiece is moved between a position spaced apart radially from the axis of rotation and a position which is central with respect to the axis of rotation. In this central position in which the axis of rotation runs through the workpiece, for example, intermediate machining steps can be carried out for complex profiles. 
     There may also be provision whereby, to vary its position, the workpiece is rotated in the fixture through an angle of rotation, in particular through 180°, about the longitudinal axis. 
     Especially short manufacturing times can be achieved if at least two workpieces are chucked on the rotating fixture and if the at least two workpieces are lathed in a common operation. 
     To manufacture the root regions or fastening regions of turbine blades and/or of cross-sectional thickenings along the longitudinal axis, there may be provision whereby the turning tool, during lathing, is pivoted with its feed direction in a radial plane and/or in a plane including the axis of rotation. 
     For a simultaneous machining of a plurality of workpieces, there may be provision whereby at least two turning tools are used, which engage on the workpiece during lathing. 
     The advantages of the invention are especially useful when at least one nonround workpiece, in particular a workpiece having a cross section which is flat transversely to its longitudinal axis, is manufactured. Examples of this are turbine blades or airfoil profiles. 
     For manufacture, a blank with a free shape, in particular with a rectangular, round or elliptic initial cross section, can be lathed transversely to its longitudinal axis. 
     In order to achieve an approximation to the final shape cost-effectively and in a short time, there may be provision whereby, for lathing, first roughing and then smoothing are carried out. In this context, roughing typically designates a manufacturing operation with a large chip removal, while smoothing is understood to mean fine machining with a small chip removal. Roughing and smoothing may be carried out in one chucking or on separate machines. 
     For this purpose, it may be necessary, during roughing, for a change in the direction of rotation of the fixture to be carried out. 
     There may be provision whereby, during roughing, the radial distance of the tool from the axis of rotation of the fixture remains unchanged over a revolution. An even better approximation to a final shape of nonround cross section can be achieved if, for the roughing operation, the tool is also moved radially during chip removal. For example, in this case, the distance can initially be kept constant, and a radial feed can take place with progressive machining. 
     There may therefore be provision whereby, during roughing, the workpiece is given a shape which lies near to the finished contour. In this case, approximation can be selected as a function of the curvature of the workpiece in the final shape and/or of the size of the workpiece. For example, the blank can be manufactured to a deviation of ½ mm or even 1/10 mm from the final shape by roughing. 
     By the workpiece being offset radially out of the axis of rotation, sufficient cutting speeds can be achieved even when the rotation of the workpiece is executed at at least 5 rev/min, preferably at least 10 rev/min. 
     In a refinement of the invention, there may be provision whereby, in one chucking, in the case of a first workpiece, on the one hand, and a second workpiece, on the other hand, different surface regions, in particular with differently curved contours running transversely to the respective longitudinal axis, are machined. Thus, for example, two tools may be provided, of which one is set up for machining a concave contour and the other for machining a convex contour, or the tool may be guided during a revolution of the fixture, without mechanically especially complicated, especially rapid return movements, such that, in one half of each revolution, a radially further outward contour is machined by the tool on the one workpiece and, in the other half of the revolution, a radially further inward contour is machined by the tool on the other workpiece. 
     To achieve the object, in a lathe of the type initially mentioned, there is provision whereby the fixture has a workpiece receptacle arranged eccentrically at a radial distance from the axis of rotation of the rotary spindle, and whereby a synchronizing device is provided, which synchronizes the feed movement of the tool carrier with the rotation of the rotary spindle. It is advantageous in this case that workpieces with nonround cross sections, that is to say profiles or contours, longitudinally to their longitudinal axis oriented parallel to the axis of rotation in the chucking position, can be manufactured, while, in contrast to the known devices and methods, the minimum cutting speed required for machining by cutting does not constitute any or essentially any limitation to the radii of curvature which can be made to the profile or to the contour. On the contrary, by virtue of the invention, a cutting speed higher that zero is always obtained. 
     For exact guidance of the workpiece during machining by cutting and to avoid centrifugally-induced or unbalance-induced vibrations of the workpiece, there may be provision whereby the fixture has a tailstock center sleeve rotatable about the axis of rotation of the rotary spindle and having a counterholding receptacle for that end of the workpiece which faces away from the rotary spindle. 
     Additionally or alternatively, there may be provision whereby the fixture has unbalance compensation for the chucked workpiece. 
     In a preferred embodiment, there may be provision whereby the unbalance compensation and the workpiece receptacle are arranged so as to be movable synchronously. Preferably, the unbalance compensation and workpiece receptacle are movable radially. For this purpose, mechanical and/or electronic synchronizing means are formed on the fixture and/or on the lathe. It is in this case advantageous that the unbalance compensation does not have to be readjusted when the position of the workpiece in the fixture is varied for the purpose of machining further surfaces. 
     It is especially beneficial if the unbalance compensation is formed by a further chucked workpiece. There may be provision whereby the workpieces are arranged so as to be variable in positions synchronously. 
     For this purpose, there may be provision whereby the fixture has an arrangement of at least two workpiece receptacles which is rotationally symmetrical with respect to the axis of rotation of the rotary spindle. 
     A change in the position of the workpieces with respect to the fixture, without these being released and the workpiece removed, can be carried out if the workpiece receptacle and/or the counterholding receptacle are/is arranged so as to be movable rotatably about an axis oriented parallel to the axis of rotation of the rotary spindle. Alternatively, or additionally, there may be provision whereby the workpiece receptacle and/or the counterholding receptacle are/is arranged so as to be movable transversely to the axis of rotation. For this purpose, for example, guide means may be formed for a movement travel which intersects the axis of rotation and/or a movement travel which leads onto the side lying opposite with respect to the axis of rotation or to an axial plane. 
     For a further improvement in the running accuracy of the workpiece arranged in the fixture, there may be provision whereby the tailstock center sleeve can be driven by a rotary drive. 
     It is especially beneficial in this case if a further synchronizing device is provided, by which the rotation of the rotary spindle can be synchronized with the rotation of the tailstock center sleeve. For example, the synchronizing device may have electronic or mechanical synchronizing means. 
     For a multistep manufacturing method, a machining unit for rough machining may additionally be provided. 
     Complex profiles, for example with cross-sectional thickenings along the longitudinal axis of the workpiece, can be manufactured if the tool carrier is arranged pivotably about an axis oriented askew to the axis of rotation of the rotary spindle, in particular about an axis lying in a radial plane. In this context, two mathematical axes are skew to one another if they neither run parallel to one another nor intersect one another. 
     For the manufacture of elongate workpieces, there may be provision whereby the tool carrier and the workpiece receptacle are additionally arranged so as to be movable with respect to one another parallel to the axis of rotation of the rotary spindle. In this case, the tool carrier or the workpiece receptacle may be arranged so as to be fixed in space or both may be set up for simultaneous contradirectional movement. 
     The invention, then, is described in more detail by means of an exemplary embodiment, but is not restricted to this exemplary embodiment. Further exemplary embodiments arise as a result of the combination of individual and/or several features of the claims and/or with individual and/or several features of the exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawing, in partially diagrammatic illustration, 
         FIG. 1  shows an overall view of a lathe according to the invention in perspective from above, 
         FIG. 2  shows the lathe according to  FIG. 1  from the front, 
         FIG. 3  shows the headstock, tailstock and tool of the lathe according to  FIG. 1  in a perspective view from above, with chucked workpieces, 
         FIG. 4  shows the headstock, tailstock and tool according to  FIG. 3  in a perspective view from below, 
         FIG. 5  shows the workpiece receptacle and counterholding receptacle from  FIG. 4  with chucked workpiece and turning tool in perspective from above, 
         FIG. 6  shows various working positions of the chucked workpiece, 
         FIG. 7  shows a view of the headstock, tailstock and tool carrier according to  FIG. 3  from the front, 
         FIG. 8  shows a sectional view of  FIG. 7  along B-B, 
         FIG. 9  shows a view of a detail of  FIG. 8 , 
         FIG. 10  shows the unbalance compensation in the event of a variation in the position of the chucked workpiece, 
         FIG. 11  shows the relative movement of the workpiece and tool with respect to one another along the axis of rotation, 
         FIG. 12  shows the relative pivoting of the workpiece and tool with respect to one another about an axis perpendicular to the axis of rotation, 
         FIG. 13  shows the relative pivoting of the workpiece and tool with respect to one another about an axis parallel to the axis of rotation, 
         FIG. 14  shows a blank of circular cross section, 
         FIG. 15  shows a blank of rectangular cross section, 
         FIG. 16  shows a turbine blade with a cross-sectional thickening, 
         FIG. 17  shows a further turbine blade, 
         FIG. 18  to  FIG. 20  show tools for use in the lathe according to  FIG. 1 , 
         FIG. 21  shows the machining according to the invention of a cross-sectional thickening in a view from the front, and 
         FIG. 22  shows the machining according to the invention, as shown in  FIG. 21 , in a perspective view from below. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a lathe, designated as a whole by  1 , in a perspective view from above.  FIG. 2  shows the lathe  1  in a view from the front. 
     The lathe  1  has a machine bed  2 , on which two horizontal linear guides  3  running parallel are arranged. A slide  4  is movable on the linear guides  3  in the Z-direction, that is to say in the drawing plane in  FIG. 2 . The drive means required for this purpose are not illustrated in any more detail. 
     Two further linear guides  5  likewise running parallel and oriented horizontally are arranged on the slide  4 . Only one of the linear guides  5  can be seen in  FIG. 1 . The linear guides  5  define a movement travel which is oriented perpendicularly to the movement travel which is defined by the linear guides  3 . 
     A further slide  6  is arranged movably on the linear guides  5  and can therefore be moved in the Y-direction along the linear guides  5  by drive means not illustrated in any more detail. 
     A further pair of linear guides  8  which run parallel and vertical is arranged on the front side  7  of the slide  6 . 
     A vertical slide  9  is guided on these linear guides  8  and can thus be moved in the X-direction, that is to say vertically, the required drive means likewise not being illustrated in any more detail. The linear guides  3 ,  5  and/or  8  may comprise rails. 
     A cross member or a build-on slide  10  is suspended on the vertical slide  9  pivotably about a vertical pivot axis. 
     A headstock  11  with the clamping chuck  12  of a rotary spindle, not illustrated in any more detail, and a tailstock  13  with a tailstock center sleeve  14  are formed on the built-on slide  10 . A drive, not evident in any more detail, is provided, by means of which the rotary spindle together with the clamping chuck  12  can be rotated about an axis of rotation. 
     A fixture  15  which constitutes a chucking point for a workpiece  16  is thus formed between the clamping chuck  12  and tailstock center sleeve  14 . The chucked workpiece  16  can then be rotated by means of the drive of the clamping chuck  12  about the axis of rotation of the spindle for lathing. 
     Arranged fixedly on the machine bed  2  is a tool feed device  17  which provides a tool  18  which engages on the workpiece  16  during lathing. 
     The tool feed device  17  is thus arranged fixedly in space in the lathe  1 , whereas the fixture  15  with the built-on slide  10  is arranged so as to be movable in the X-, Y- and Z-direction, as desired, and so as to be pivotable about said pivot axis for the suspension of the built-on slide  10 . 
     In further exemplary embodiments, the built-on slide  10  is not suspended, but is set up, and/or there is provision whereby the tool feed device  17  is arranged so as to be movable in one direction of space or a plurality of directions of space and/or the built-on slide  10  is arranged so as to be fixed in space. 
       FIG. 3  shows the built-on slide  10  with the fixture  15  in a view in perspective from above, and  FIG. 4  shows the same in a view obliquely from below. 
     The built-on slide  10  has on its top side  19  an extension  20 , at which the suspension of the built-on slide  10  engages on the vertical slide  9  and by which the pivot axis of the built-on slide  10  is defined. The drive provided for this purpose is not shown in any more detail for the sake of greater clarity in the illustration. 
     In  FIG. 3 , two workpieces  16  are chucked symmetrically, and free of unbalance, in the fixture  15 . For this purpose, the clamping chuck  12  has arranged on it two workpiece receptacles  21 , at which the workpieces  16  are in each case chucked with one end. The workpieces  16  are chucked with their other end on corresponding counterholding receptacles  22  which are arranged on the tailstock center sleeve  14 . 
     The tool  18  is arranged on a tool carrier  23  which by means of the tool feed device  17  can be moved radially with respect to the axis of rotation to the clamping chuck  12 , the axis of rotation below, and can be fed radially and/or tangentially. When this adjusting movement is executed synchronously with the rotation of the clamping chuck  12  during chip removal on the tool  18 , surfaces which do not lie on a cylinder surface area concentric to the axis of rotation can be manufactured by cutting on the workpieces  16 . Workpieces  16  which are nonround in virtually any way can thus be manufactured. 
     The workpiece receptacles  21  and the counterholding receptacles  22  are in each case guided, for example, in grooves  24 ,  25  and can be adjusted radially between the machining steps, in order to arrange the workpieces nearer to the axis of rotation or further away from this. 
     In order to compensate unbalances caused, for example, by an asymmetric arrangement of a workpiece  16  or a plurality of workpieces  16 , unbalance compensation  27  in the form of a radially displaceable mass is provided on the clamping chuck  12  in a recess  26 . 
     This application uses the terms “radially” and “axially” with respect to the axis of rotation of the rotary spindle and of the clamping chuck  12 . 
       FIG. 5  shows a workpiece  16  chucked in the fixture  15  during cutting machining by the cutting edge  28  of the tool  18 . 
     The workpiece  16  has a longitudinal axis which extends between the workpiece receptacle  21  and the counterholding receptacle  22  and which is oriented parallel to the axis of rotation  29 . The workpiece  16  is chucked eccentrically at a radial distance from the axis of rotation  29 , and therefore the axis of rotation  29  does not run through the workpiece  16 . To compensate the unbalance caused thereby, the unbalance compensation  27  is likewise arranged so as to be offset radially with respect to the axis of rotation  29 . 
     The radial position of the tool  18  with respect to the workpiece  16  is then controlled during a revolution of the workpiece  16  about the axis of rotation, such that, after chip removal, the nonround profile illustrated is obtained on the workpiece  16 . Airfoil profiles can also be manufactured in this way. 
       FIG. 6  shows, for example, a further workpiece  16  which can be manufactured by means of the lathe  1 . In this workpiece  16 , the tool  18  is adjusted radially during cutting machining, in such a way that a surface region  30  which points radially outward in the chucked position shown and which has a contour concave in regions is formed on the workpiece. 
     For further machining steps, the position of the workpiece  16  in the fixture  15  can be varied in that the workpiece  16  is moved into a second radial position  31  centrally with respect to the axis of rotation  29  or a third radial position  32  on the diametrically opposite side or into an intermediate position. The positions  31 ,  32  are in this case shown merely by way of example. Any freely definable positions may also be assumed. 
       FIG. 7  shows a view from the front with two identical workpieces  16  which are chucked in the fixture  15  for lathing. 
       FIG. 8  shows a sectional view along the sectional plane B-B in  FIG. 7 . The nonround contour of the profile  33  of the workpieces  16  can be seen clearly. 
     It is likewise evident that, within a revolution of the workpieces  16  about the axis of rotation  29 , in each case different surface regions which do not correspond to one another are machined on the workpieces  16  by the tool  18 , even through the profiles  33  of the workpieces  16  are identical to one another. 
     To machine other surface regions, the position of the workpieces  16  in the fixture  15 , that is to say in relation to the rotary spindle with the clamping chuck  12 , has to be varied, for example by pivoting the workpiece receptacles  21  and counterholding receptacles  22  about the longitudinal axis of the workpieces  16  and/or by moving the workpieces  16  radially, as described above. 
       FIG. 9  shows as a detail a view of  FIG. 8 , the workpiece  16  having been pivoted about its longitudinal axis through an angle in relation to the position in  FIG. 8 . 
     The workpiece  16  is chucked on two sides at its end or foot  39  by means of adjustable clamping jaws  34 , the clamping jaws  34  being guided linearly in guide elements  35 . 
     The illustrated contour of the surface region  30  on the workpiece  16  can be manufactured in that the radial distance of the tool  18  and, in particular, of the cutting edge  28  from the axis of rotation  29  is correspondingly varied during chip removal on the workpiece  16 . For this purpose, a synchronizing device, not illustrated in any more detail, synchronizes the rotation of the workpiece  16  about the axis of rotation  29  with the feed movement of the tool  18 . 
     So that the surface region  36  pointing radially inward in the chucking shown can also be machined by the tool  18 , the position of the workpiece  16  in the fixture  15  must be varied, for example by pivoting about the longitudinal axis, perpendicular to the drawing plane of  FIG. 8 , of the workpiece  16  through an angle of 180° or by moving the workpiece  16  to the position lying diametrically opposite with respect to the axis of rotation  29 . 
     Thus, virtually any, even asymmetric, contours of profiles  33  which are composed of surface regions  30 ,  36  machined in successive machining steps can be manufactured. In this case, these surface regions  30 ,  36  may be contiguous to one another in rounded transitional regions  37  or at edges  38 . 
       FIG. 10  shows the chucked workpiece  16  in the three positions according to  FIG. 6  in a view from the front. 
     The workpiece  16  is in each case chucked with its head  40  in clamping jaws  41  of the counterholding receptacle  22 . The clamping jaws  41  are basically designed in the same way as the clamping jaws  34  and are arranged movably. 
     A partially cutaway illustration shows that the counterholding receptacles  22  are guided in the groove  25  for radial adjustment. 
     To compensate the unbalance, as described, the unbalance compensation  27  is moved synchronously with the workpiece  16  into position  42 ,  43  offset eccentrically with respect to the middle position. For this purpose, the lathe  1  has a mechanical and/or electronic synchronizing device, not shown in any more detail. 
       FIG. 11  shows in a view from the front how the workpiece  16  can be moved by means of the workpiece receptacle  21  in relation to the tool  18  longitudinally with respect to the axis of rotation  29  and to the longitudinal axis of the workpiece  16 , in order to carry out lathing on further axial portions of the workpiece  16 . A changed axial position  44  of the tool carrier  18  with respect to the workpiece  16  is thus obtained. In this case, the tool  18  may remain fixed in space, and there may be provision whereby the manufactured profile  33  of the workpiece  16  changes along its longitudinal axis. 
     It is evident, furthermore, in  FIG. 11  that the tailstock  13  is arranged so as to be movable along the axis of rotation  29  with respect to the built-on slide  10  on the latter, in order to allow different lengths of the workpiece  16 . 
       FIG. 12  shows that the tool carrier  23  with the tool  18  can be pivoted about a pivot axis which lies in a radial plane and is perpendicular to the drawing plane in  FIG. 12  if the profile to be manufactured on the workpiece  16  so requires. This pivoting movement may be executed, for example, by pivoting the built-on slide  10  about its pivot axis. Various positions  45  of the tool carrier  23  are illustrated by way of example, and even intermediate positions can be assumed. 
       FIG. 13  shows a view from the side of the tailstock  13 , in which various working positions  46  of the tool carrier  23  with the tool  18  are shown. These positions  46  merge one into the other as a result of the pivoting of the tool carrier  23  and of the built-on slide  10  with respect to one another about an axis which is oriented parallel to the axis of rotation. Intermediate positions may also be assumed. 
       FIG. 14  shows a blank  47  of round cross section, from which a workpiece  16  can be manufactured.  FIG. 15  shows a blank  48  of rectangular cross section. In the blanks  47 ,  48 , the edges projecting toward the tool  18  are first machined in a roughing operation, in order to achieve an approximation to the desired final shape of the workpiece  16 . 
       FIGS. 16 and 17  show by way of example two possible workpieces  16  which can be manufactured by means of the method according to the invention on the lathe according to the invention. In this case, the workpiece  16  may have a thickening  50  of its profile along its longitudinal direction. Turbine blades are illustrated diagrammatically by way of example. 
       FIGS. 18 and 19  show by way of example turning tools  18  with different cutting edges  28  for manufacturing different contours of the profile  33  of the workpiece  16 . 
       FIG. 20  shows a tool  18  with a milling cutter  49 , by means of which, for example, the planar surfaces of the thickening  50  can be manufactured. 
       FIG. 21  and  FIG. 22  show this manufacture which may follow or precede the lathing described above. 
     With regard to the lathe  1 , it is provided that the workpiece  16  intended for lathing by means of a tool  18  is chucked with its longitudinal axis parallel to the axis of rotation  29  of the rotating fixture  15 , in such a way that the axis of rotation  29  does not intersect the workpiece  16 , and in such a way that the position of the workpiece  16  in the fixture  15  is varied between two machining steps of lathing in such a way that hitherto unmachined surface regions  30 ,  36  are brought into the working range of the tool  18 .