VERFAHREN ZUR SCHLEIF-KOMPLETTBEARBEITUNG VON WELLENFÖRMIGEN WERKSTÜCKEN MIT ZYLINDRISCHEN UND PROFILIERTEN ABSCHNITTEN

METHOD FOR GRINDING COMPLETE TREATMENT OF WAVY TOOL PIECES OF CYLINDRICAL AND PROFILED SECTIONS

The invention relates to a method for grinding at least a respective cylindrical and profiled portion having shaft-like workpieces on the same grinding machine as complete machining.

In this invention, for example, gear shafts, rotors for hydraulic pumps or flow meter, rotors for vane pumps and rotors for compressors for example, compressors, blowers, pumps or similar applications will be understood by shaft-like workpieces. However, the invention described below to find wavy workpieces to other shaft components such as camshafts, crankshafts, etc. Application in terms of a broad interpretation of the term. In known methods for grinding complete machining of shaft-like workpieces having cylindrical and profiled sections, as is the case for example with gear shafts, the necessary recesses, flat sides and diameters generally in separate work sequences and often ground in a machine. In contrast, the also ground at the shaft-like workpieces to be ground profile sections or gears on separate machines. The use of multiple, in the manufacturing process often arranged in succession machines requires a high investment in machine tools and additional space in the production halls. This is also true for rotor parts which have cylindrical and the profile sections and are ground in a similar manner for the various applications.

However, it is also already known to grind shaft-like workpieces having cylindrical and profile portions on a machine. The grinding of cylindrical sections relates as a rule from the grinding of plan shoulder surfaces with a, for example, which are present between adjacent outer cylindrical surfaces of different diameters. In DE 199 21 785 B4 discloses a method for grinding the convex running surfaces and Au ßend urchmessern on shafts with at least one disc-shaped Wellenab- cut and an appropriate grinding machine for performing the method known. The shaft portion to be ground is to be ground in the sense of both complete processing with respect to the cylindrical portion or the cylindrical portions and the profiled portions. The profile sections are described in these processes according to the described embodiment there as a disc-shaped shaft portion having a convexly curved surface. Such convex curved surfaces provide profile sections. The known method is now directed to the fact that all the grinding operations, ie, a grinding operation for grinding the convex frontal running surfaces on the disc-shaped shaft portion and a second grinding operation for grinding the respective desired th outer diameter or cylindrical portions of the the shaft portion to be ground in a single clamping operation. This means that during the entire grinding process, the workpiece remains at least spanned between centers between a workpiece headstock and a tailstock. This setup is therefore not solved during the entire processing.

In WO 2012/100 307 A8 such a method for grinding complete machining of shaft-like workpieces is described with cylindrical and profiled sections, which is to screw-shaped profiles for rotors is, for example, compressors with the profiled sections. In this known method, the workpiece during the entire processing is also firmly clamped, so that the clamping operation is not solved. Regardless of how many grinding operations in the sense of pre-grinding, finish grinding, grinding a steady seat, grinding of the cylindrical sections are performed etc., the clamping of the workpiece is made at the beginning of the grinding, and the workpiece remains constant during the entire grinding operation in this chucking curious; excited.

This also corresponds to the now well-known technical knowledge, according to which the workpieces to achieve tighter tolerances and improved shape and positional characteristics of a machine in a single set are ground. The well-known expertise currently assumes that in each lashing Fertigungsqualitätsein- are buses because of possibly occurring re-clamping available.

From DE 10 2010 005 630 A1 of the basic technical building a machine is described with which a machining of shaft-type workpieces according to the previously gewürdig- th WO 2012/100 307 A8 can take place. In this known grinding center is been described above all that in addition a supply magazine with required for the respective abrasive wheels to varying cooling nozzles or cooling nozzle sets may be arranged in the running means of this known grinding center grinding complete machining of the workpiece will remain completely tensioned.

In contrast, the object of the invention, as the to be ground wave-shaped workpieces having cylindrical and with profiled sections to increase the manufacturing accuracy of such complex components here further.

This object is achieved with a method having the features of claim. 1

Advantageous developments are defined by the dependent claims.

According to the inventive method of grinding at least a respective cylindrical and profiled portion workpieces having such a complete machining on one and the same grinding is carried out. The workpiece in the grinding machine is ground in a first setup in a first grinding operation and then ground in a second grinding operation, after the first clamping has been released and then a second clamping the workpiece has been produced.

This procedure according to the invention, wherein namely taking place on the same machine set-up between individual grinding operations, and without the workpiece must indeed be removed from the processing station, is selectively dissolved and then again clamped the workpiece for its further processing, and as a rule with the same fixtures. Contrary to the prevailing opinion according to the knowledge of the skilled man has been found in a surprising manner that the clamping conscious account when such a procedure, in which between the individual grinding operations and is specifically solved more improved production quality of the workpiece after grinding, especially in respect may be on the size, form and position tolerances achieved. This depends in part to the fact that in the processing of workpieces such. B. arises at different grinding stock allowances by the cutting a different heat. This varying Zerspanungswärme can expansions at different heating or cause distortions on the workpiece, which can be compensated by an interim releasing the clamping.

Another reason is that in the preparation of Rohwerkstückes different residual stresses in the material are present or remaining, particularly where these workpieces are subjected to prior to grinding or special heat treatments such as hardening. In such a case, even small differences within the permissible technical tolerances come in Rohwerkstück from different batches in the production to fruition, as the heat treatment conditions ig can be kept from batch to batch in the individual batches are not 100% constant.

Another reason for residual stress in the workpiece may result from whether beispielswei- se and scrap material in the production of the raw material or the Rohwerkstückes is used, which indeed is still within the permissible technical tolerances for Rohwerkstück or the Rohiing, but in subsequent may lead to additional processing steps tensions and in connection therewith deformation of the workpiece.

Among the manufacturers of here in question shaft-type workpieces with cylindrical and profile sections, it is also common for the materials for the Rohwerkstücke with the same specification from different manufacturers, and often even from different countries, to be procured. Even if the specifications are the same, the Werkstü- behave blocks in Schieifbearbeitung particular by the release of internal stresses sometimes quite different. This problem of liberated during the machining stresses from the material structure inevitably means that the finished workpieces, difference in their size, form and position tolerances despite otherwise constant grinding process parameters. Here, variations in dimensions in the micron range down to the hundredth of a millimeter range are quite possible and common. In particular, for rotor shafts soft be incorporated into screw rotors and must mesh as a pair of male and female rotor shaft very accurately with one another, such variations can not be tolerated, low-wear operation, a corresponding seal during rolling of the profiles, and the like to be ensured. But the temperature difference of the Rohwerk- pieces, which are fed to the grinding machine, exerts an influence on the accuracy. Here, for example, the differences in the temperatures of the fed to the machine workpieces and the temperatures in the interior of the processing machine part in no longer negligible way of acting. This temperature difference affect the greater, the more pronounced the fluctuating Rohteiltemperaturen of the workpieces, which are fed to the processing machine.

Another important point, which is in achieving extremely high accuracy of such components of importance is the type of pre-processing. Thus, the blanks or Rohwerkstücke can be designed in such a way that the grooves or teeth of the Profilab- sections by milling or other machining processes have already been pre-processed. When castings or forgings, it is for larger grooves or teeth in some cases also possible that the grooves are pre-cast already in its basic form or pre-forged, in which case it a higher grinding allowance than z. B. having been milled grooves or teeth, when they are fed to the grinding machine. Since the so-called casting skin is abraded in grinding, the risk of released tension during grinding there is particularly high, being free to be the residual stresses in the grinding of cast skin. While avoiding all of the aforementioned disadvantages, it is possible to significantly improve the production quality again. The improved manufacturing quality is given by the fact that through the intermediate release of the stretching, the thus carried out, moreover, that the positioning of the workpiece is maintained in the grinding machine, the warping of the workpiece due to the above reasons, in the processing by grinding, so to speak " -.. is given "this means that the workpiece can relax between time upon release of the tension, so that during subsequent grinding operations can be ground to a relaxed and firmly clamped workpiece again, as already described, the distortion of the workpiece results by the in machining of the workpieces freed stresses in the structure of the material. Above all, this concerns in particular the voltages at the surface of the workpiece at the locations at which ground. By loosening the clamping of the workpiece can in subsequent re-stretching and Schle are just then machined precisely ifbearbeitung an at least largely stress-free workpiece. In general, the workpieces are initially clamped in the machine, the

Workpieces are firmly clamped in the machine between the peaks, as is commonly known in the art. In order to grind the profiled regions of the grooves or serrations, the workpiece must additionally be clamped radially free of play. This is preferably realized by a so-called compensating chuck. In these chucks the workpiece is centered by the tip of the chuck, and

Clamping jaws lie down in between the tips of Werkstückspindel- and tailstock clamped state balancing of the workpiece at which the diameter of, the clamping force applied by the tension, the workpiece balancing and radially stiff that is free of play, clamps.

Around the workpiece during the machining program-controlled to be able to selectively rotatably drive, the chuck is fixedly mounted on a workpiece spindle, wherein the rotary drive to the so-called C-axis. To be able to also the shaft end, to which the chuck clamps the workpiece grinding, this can or the clamping jaws can be retracted in geöffne- th state. Thus, the workpiece on the shank-side end is free, so that the clamping diameter can also be ground. Here, the workpiece is only clamped between the centering points. The friction between the driven center point and the center of the workpiece to transmit the torque required for grinding to the rotation of the workpiece. The workpiece to be ground is clamped during the grinding in the way that this is clamped between the tips and is still balancing clamped to the radial entrainment by the chuck. Since the shaft parts generally have such a diameter to length ratio that these have to be supported during the machining, a Lünet- is preferably first tensitz on the workpiece is ground. This is only required if the diameter-to-length ratio requires additional support.

According to a first embodiment, the loops of the diameter and the flat sides is preferably carried out with a grinding wheel, which is carried out for the rough grinding. The cylindrical portion on the workpiece is preferably performed with a first, cylindrically shaped grinding wheel by means of a longitudinal traverse grinding. The profiled section is produced with a second profiled grinding wheel by profile grinding. the grinding wheel is preferably so dressed that the so-called cut of the grinding wheel is trued at an angle for grinding the diameter and axial sides. Machining mainly in the peel grinding takes place in the short, conical trained area of ​​the grinding wheel. The outer diameter of the grinding wheel machined while relatively low, ie, the surface of which is used only for the smoothing of the surface. With such a grinding wheel can also be ground flat. In parallel to the axis center axis of the grinding wheel with respect to the central axis of the workpiece in the grinding of flat sides remains a so-called sunburst finish on the ground surface. Since these rays cut is often undesirable, the corresponding workpiece is further preferably provided with an inclined grinding wheel be ground on its diameter and axial sides. The grinding of the diameter ranges is also carried out the rough grinding method. The grinding of the flat sides is then ground with the inclined side surface of the grinding wheel dressed in Schrägeinstechschleifverfahren. However, it is also possible, preferably, with a wider running grinding wheel which is capable of angular infeed grinding, at the same time to grind several diameters in one or more Einstechschleifvorgängen or sequentially. In such a case, the grinding of the flat sides also takes place with the inclined side surface of the dressed grinding wheel.

Preferably, the first grinding wheel is arranged on a first grinding spindle and said second grinding wheel is more preferably arranged on a second grinding spindle head. The advantage of separate wheel heads for the first grinding wheel and the second grinding wheel is that a higher flexibility is given during grinding. In the presence of two wheel heads and their arrangement on both sides of the workpiece, there is also the possibility of certain sections of the workpiece at least partly hidden time to edit. For time-parallel processing of respective regions on the workpiece and arrangement of the grinding spindle poles on both sides of the workpiece also can be achieved that are compensated for at least to a considerable extent in the grinding of the one grinding wheel impressed in the workpiece grinding forces by the other grinding wheel.

According to one embodiment, the workpiece is clamped between centers which are introduced into the end faces of the workpiece and defining the longitudinal axis thereof. One of the spikes is arranged on the tailstock, and the other tip is arranged on the workpiece spindle head. In the first setup the tip exerts on the tailstock by an axially directed pressure load from a corresponding clamping pressure, which is sufficiently high, at least for the grinding of cylindrical portions and / or the flat sides. The tip located at the tailstock can be made of a state in which the axially directed pressure load is exerted on the workpiece can be transferred for releasing the clamping in a drucktosen state. In such a pressure-free state, the tip engages the tailstock still in the centering bore on the workpiece at the side facing the tailstock side of the workpiece, and thus ensures the orientation of the workpiece on the plane defined by the centering longitudinal axis of the workpiece. By the unpressurised state of the tip on the tailstock, the workpiece given the opportunity to compensate for certain liberated during grinding internal stresses so that be- seen for the next grinding operation when re-clamping the tips of the workpiece can be largely free ground of internal stresses.

To release the clamping, that is, the pressure loss Tellen the tip on the tailstock the tailstock is moved along its Z-axis. It is thus as it were disengaged from the facing of the tailstock centering of the workpiece. By "disengaged the pressure-free state of the center point is understood in the centering bore of the workpiece, in this context, in which a rotary drive about the clamping between the tips of the workpiece is no longer possible. When grinding of the profile sections higher grinding forces usually arise, which are introduced through the respective grinding wheel in the workpiece. To prevent now that the frictional forces at the tip of the workpiece headstock for rotation of the workpiece may not be enough reliable in the sole clamping of the workpiece between the tips with the relatively large grinding forces during grinding of the profile sections, the workpiece headstock, an additional clamping device is provided, which the workpiece additionally tensioned on the outer periphery of a cylindrical portion. Preferably, the additional clamping device clamps the workpiece with its engaging on the periphery of the workpiece clamping jaws. If now will be made between individual grinding operations in the profile grinding, for example between the Profilvorschleifen and the finish grinding of the profile, a release of the first setup, it is the purpose of the complete stress relieving the workpiece, that is also to compensate for the released during grinding internal stresses, the tensioning device to resolve when the tip on the tailstock is depressurized.

Especially with longer workpieces in the first Schlerfoperation at least one steady rest is ground, and thereafter pre-ground in the second grinding operation of the profiled section. In a third grinding operation, the cylindrical portion and the existing on the workpiece end faces then are finish-ground, followed by the finish-grinding of the profiled section adjoins in a fourth grinding operation. Preferably, the clamping is achieved in each case, and then again clamped the workpiece before each subsequent grinding operation starts between all the successive grinding operations.

After finish grinding the steady a steady rest for supporting the workpiece at this steady rest is preferably employed after it has been ground. The supporting means of a bezel is especially advantageous when grinding operations are carried out at longer workpieces, in which only a grinding wheel with the workpiece is engaged. The grinding of the steady represents the first processing step, during which the workpiece is firmly clamped in the machine, that is in the first clamping. After grinding the steady other diameters are then pre-ground with possibly located between plane surfaces or even finish ground to the same. The grinding of the diameter comprises, depending on the geometry of the workpiece and the grinding of the individual diameter sections of different diameter interconnecting end faces.

The present invention is based on the idea that by loosening the clamping process spindle stock between successive running grinding operations, while ensuring the holding of the article to be sanded workpiece on the by the tips of the workpiece and the tailstock, as well as existing in the end faces of the workpiece Zentrierboh- conclusions defined longitudinal axis internal stresses are reduced, which represents the longitudinal axis of the referenced for grinding reference axis. In subsequent grinding operations on the workpiece can then be sanded free of such internal stresses or at least considerably reduced internal stresses. The after each release of the clamping subsequent further grinding in the presence of a substantially stress-free in the workpiece internal state in any case leads to improved grinding results, namely contrary to the prevailing opinion according to which the work piece as far as possible during the entire grinding operations firmly and without intermediate detachment of the clamping to be held in this setting.

The release of the tailstock-side tip can also be effected in the manner that the tip is retracted by a certain amount, that is no longer present in the center. Here, the workpiece in this state is then lie on the so-called Vorabiageprismen and then clamped again. By doing so, the same technical effect is achieved as in the previously described procedure.

Further advantages and embodiments of the inventive method are described in detail in the following figures. In the drawings: Figure 1 is a plan view of a grinding machine for carrying out the invention

Method with a wheelhead and a station for clamping a workpiece; a plan view of a grinding machine for performing the method according to the invention with two wheel heads, and a station for clamping a workpiece; is a partial plan view of a between centers spanned for carrying out the method of the invention the workpiece before the start of grinding a nice Lü- seat;

4A shows a partial plan view of FIG 3 at pre-grinding of the profile section in the form of a toothing or grooves with abstützender bezel; Figure 4B is a partial view in direction A of the workpiece according to Figure 4A during the

Grinding his profile section; Figure 4C is a partial sectional view BB in Figure 4B during the grinding of the designed as Geradlängsnuten profile section of the workpiece ;;

Figure 5 is a partial plan view according to Figure 3 during finish grinding of the central diameter and the flat sides of the workpiece according to the inventive method;

Figure 6 is a partial plan view according to Figure 3 during finish grinding of the teeth or

Grooves of the workpiece in accordance with the inventive method; and

Figure 7: Examples of grindable with the inventive process workpieces having cylindrical Planschulter- and profile sections.

In Figure 1, a plan view is shown on a grinding machine for performing the method according to the invention, wherein a workpiece is clamped so that it enables the implementation of the method for grinding complete processing for shaft-like workpieces and shaft parts 10th The grinding machine shown in plan view includes a machine stand 1, a angeordne- on the machine stand 1 th Werkstückspindeistock 2 with CNC-controlled C-axis and a tailstock 3 as a grinding center. Between the Werkstückspindeistock 2 and the tailstock 3, the workpiece not shown, is so stretched that its geometrical longitudinal axis coincides with the axis of rotation and tensioning. 4 A cross slide is connected in parallel, which is indicated by the marked as Z-axis double arrow, and a right angle, which is indicated by the designated as the X axis further double arrow to the axis of rotation 4 of the workpiece CN-controlled. The cross slide carries on vertical guide tracks 19, CN-controlled, which is illustrated by the similarly indicated as double arrow Y axis, a first wheel head 5, to which a grinding spindle 9 is fixed with a grinding wheel. 11 Another CNC-controlled adjustment is made by a horizontal, arranged at right angles to the rotational axis 4 of the workpiece CNC swivel axis 12, which is marked as A-axis and displayed.

Thus, grinding wheels can be used by cylindrical or conical portions on the shaft portion in Schrägeinstechschleifverfahren for grinding, it is preferably provided on the carriage for the Z-axis of a pivot axis, which has a vertically arranged pivot axis 13 and is designated in Figure 2 as B-axis. In Figure 1, this is

Pivot axis not shown, since it is only necessary to grind with an angle employee grinding wheel 11 for rough grinding or Oblique. That is, it can be ground in Schrägeinstechschleifverfahren, or it can be ground by pivoting the B axis also cones. However, if this B-axis, that the pivot axis 13 is not present, it is also possible to provide this processing from the top of the shaft diameter.

Further, a dressing spindle 8 is provided, which carries a diamond wheel and is used for dressing the grinding wheel 1. 1 Furthermore, a device 14 for changing the grinding wheel 1 1 is shown. The grinding wheels are accommodated in a holder in the form of a magazine and are fed from the magazine of the respective grinding spindle by means of the implementation of the robot 15 °. The reaction robot 15 includes a gripper unit 16, by means of which it extracts from the storage magazine as necessary by the desired abrasive wheel and, optionally, to a corresponding to the grinding wheel certain cooling nozzle set 17, and both feeding into the area of ​​the operative position of the grinding wheel on the workpiece. It is also possible that the cooling nozzle set 17 is taken independently of the grinding wheel with the reaction robot and is guided to the grinding point of engagement, which can occur during grinding.

In the rear of the grinding machine shown in Figure 1 above, a cabinet 18 is provided, which includes the CNC control of the grinding machine, with which the grinding machine is controlled.

In figure 2 a top view is shown on a grinding machine for performing the method according to the invention, which has a first wheelhead 5 and a second wheel head twentieth Here, the basic structure of the grinding machine in plan view is shown. In this grinding center a workpiece headstock 2 and the tailstock 3 are arranged on a machine stand. 1 Between the workpiece headstock 2 and the tailstock 3, the clamping and rotation axis 4 is formed for the workpiece 10, which coincides with the longitudinal axis of the workpiece. On a workpiece spindle 2a of the workpiece spindle head 2 (C-axis), a chuck 6 is mounted, which receives a centrally circumferential tip, which is not shown, and in addition balancing jaws 6a (also not shown) has. These clamping jaws clamp the workpiece at its periphery firmly. This chuck is designed mainly to introduce greater driving moments in the workpiece. This is required, for example at least during the grinding of the profile sections of the workpiece 10th In order to compensate at the clamping point, the run-out with respect to the formed by the clamping and center axis of rotation 4 as well as all other dimensional and positional tolerances, the jaws 6a of the chuck 6 are executed balancing. Such applications for chucks are already known in the art, so is omitted the description of the operation of which here. A first cross slide, which is shown in Figure 2 to the left, is connected in parallel, which is represented by the ZI- axis in the form of a double arrow, and a right angle, which a double arrow is shown in Figure 2 to the left by the X1 axis in the shape also, to axis of rotation 4 of the workpiece 10 CN-controlled. The first cross slide carrying a first grinding spindle head 5, to which a first grinding spindle 9 is mounted with a first grinding wheel. 11 WEI tere CNC-controlled adjustment are provided in that a horizontal adjustment to the workpiece longitudinal axis 4 (A1 axis), and an adjustment possibility over the vertically arranged at right angles to the rotational axis 4 of the workpiece 10 CNC swivel axis (B1-axis) are present , In the front region of Figure 2, the first grinding spindle is shown mounted 9, which serves to receive the grinding wheel 1. 1 In DIE ser grinding spindle 9, the grinding wheels 11 may be changed automatically under program control by a not-shown grinding wheel-change device. then the appropriate Kühlschmiermitteldüse or the appropriate cutting fluid nozzle set must be mitausgetauscht to the grinding wheel in a known manner which is not shown separately in FIG. 2

To the left in Figure 2 illustrated the first grinding spindle head 5, the cylindrical diameter and the flat surfaces are ground on the workpiece 10th

Further, in Figure 2 the left-sided axis parallel to the workpiece spindle 2a (C-axis) directing a waste spindle 8 is arranged, which is used with its diamond wheel to dress the first grinding wheel 11 of the first wheel head. 5 The means for changing the grinding wheel 1 1 is not shown separately in FIG. 2 The grinding wheels 11 of the first wheel head 5 are used for grinding the shaft parts respectively of the cylindrical portions of the shaft portion, that is, it will be with these grinding wheels all the outer diameter of the cylindrical see portions, conical portions and similar contours ground.

2 shows a second cross slide is on the right side in parallel, which is characterized as a Z2-axis by a double arrow, and at right angles, which is also shown in Figure 2 as X2-axis with the double arrow to the axis of rotation 4 of the workpiece 10 CNC controlled traversable bar. This second cross slide carries a vertical CNC controlled traversable (Y2-axis) the second wheel head 20 to which a grinding spindle 22 is attached with a second grinding wheel 21st Another CNC-controlled adjustment is made by a horizontal, the axis of rotation 4 of the workpiece 10 disposed CNC swivel axis, which is shown in Figure 2 as A2-axis. In the front area of ​​the grinding machine according to FIG 2, a grinding spindle is mounted, which serves for receiving the grinding wheel 21st On this grinding spindle 22 (see Figure 4B), these grinding wheels can be changed automatically under program control by a likewise not shown, grinding wheel-change device. then to the second grinding wheel 21 - as long as it is necessary - the right Kühlschmiermitteldüse or appropriate cooling lubricant mitausgetauscht jet set in a known manner, but this is also not shown separately. A second dresser 23 for dressing the grinding wheel 21 for the arranged on the right in Figure 2 is the front wheel head 20 provided in the grinding machine on the right side of the machine.

In the rear of the grinding machine the cabinet not shown in Figure 2 is arranged Toggle which receives all the electrical control of the machine.

For grinding the respective workpieces are fed to the grinding machine 10 in a known manner, for example via an internal loading gantry or by a valve disposed on the grinding charge gateway in terms of a loading or unloading or removed from the machine.

The illustrated in Figures 1 and 2 principal structure of a grinding machine is used for carrying out the method according to the invention, because the complete machining of the cylindrical portions, flat sides and Profilab- sections having workpiece is such achievable with this basic construction of the grinding machine that, by processing or during released internal stress between the grinding operations can be reduced or compensated for the processing in the workpiece so that subsequent grinding operations can always be performed at an at least largely freed of internal stresses workpiece. The sequence of the method according to the invention will now be described in detail with reference to the successor constricting figures.

3 shows a partial plan view of a part of the process of the invention embodying grinding machine is shown in which the workpiece is clamped between the tips, before the grinding of a steady seat is executed. In Figure 3 this is complete machining of a workpiece 10 in the form of a shaft part illustrated in principle. This shaft member is received between a workpiece headstock 2 with CNC-controlled C-axis and a tailstock 3 in one setting between the tips 2b, 3a. In order to apply the required torque at the grinding operations, particularly for the grinding of the profile sections, is incorporated to a shaft end of the shaft 10a a from the prior art in itself already known, balancing and axially retractable chuck 6 to the work piece spindle 2a. In the extended position of the chuck 6, and its clamping jaws 6a, it can be firmly clamped on the shaft-side shaft Dende 10a of the workpiece 10 so that very high radial torques are transmitted to the workpiece 10 during the grinding operation. This will be necessary in the form of groove or tooth geometries in most cases, the grinding of the profile sections 1 c. As shown in Figure 3, the jaws 6a of the chuck on the clamping area of ​​the workpiece, that is applied to its schaftseitigem shaft end. Therefore, in such tensioned state, the cylindrical outer contour can not be sanded this shaft-side shaft end. It is therefore necessary that the jaws 6a are disengaged from the workpiece 10 for grinding said clamping portion and the chuck is retracted with its jaws 6a. For grinding of the cylindrical outer areas, however, the work piece remains between the tips 2b, 3a firmly clamped. The entrainment of the workpiece 10 to its rotation by the friction between the centering tip 2b at the chuck and the workpiece 10 present in the center, which engages in this centering 2b takes place. On the workhead opposite side of a tailstock 3 is provided, which engages by means of preferably hydraulic actuator in which the centering tip 3a of the tailstock 3 disposed side facing the center. The tailstock 3 is movable in the axial direction of the workpiece so that the workpiece is held in a centered manner between the two centering points 2b and 3a, so with a corresponding formation of an axial thrust that a rotary driving is ensured by the workhead. 2

Grinding a steady seat 25 is now in the position shown in Figure 3 way after the rough grinding method with inclined employee grinding wheel 11. After completion of this grinding operation, the grinding of the steady rest is achieved, the clamping of the workpiece 10, so that the workpiece can relax and the inner free, voltages. In addition, the chuck is achieved with its clamping jaws from the workpiece. In this state, the tailstock 3 is depressurized and is located in the center of the shaft portion only. Thereby, the work piece is no longer clamped firmly, nevertheless but its centered position is relative to the clamping and rotation axis 4, that is, the longitudinal geometric axis of the workpiece 4 retained. A loss of accuracy may not occur, but the accuracy of the grinding result is increased by the fact that between the two successive-sequential abrasive operations, the workpiece has a possibility to relax, so that subsequent grinding operations in a relaxed, ie, internal stress in the

Substantially free workpiece can be ground.

In principle, it would also be conceivable that the tailstock tip 3a to solve completely from the Center for the up voltage; in such a case, however, would have to be supported by, for example, an additional gripper or a further support ensure that the workpiece is supported in this state. Once the expansion process has been performed, during which, of course, the grinding operation is interrupted, then a re-clamping of the workpiece, so that a subsequent grinding operation may follow.

In Figure 4A, a partial top view according to figure 3 at pre-grinding of the tread portion in the form of a toothing or of grooves with employee / abstützender bezel is shown. The pre-grinding of the tread portion 10c by means of a electroplated grinding wheel 21. This takes place in controlled manner known per se by an interpolating process via the CNC axis or by means of CNC-controlled axes. Regarding the accuracy to be achieved, the electroplated grinding discs 21 are well suited for pre, above all, because they can achieve a very high cutting volume per unit of time.

According to this grinding operation as a pre-grinding of the tread portion, the clamping of the workpiece to compensate for optionally present in the workpiece by the grinding internal stresses 10c is released, and indeed in such a way that the jaws 6a of the chuck 6 released and the tailstock tip 3a just depressurized in the center the shaft portion 10 waits comparable. The workpiece is not firmly clamped, but maintains its defined position, which is in accuracy for subsequent grinding operations of importance. After the relaxation of the workpiece 10, this is again firmly clamped in a known manner after the internal stresses in the workpiece have become available by releasing the clamping. The relaxation of the workpiece is preferably useful both after the rough-and after the finish-grinding of individual sections, at least as long as the complete machining on the workpiece is not yet complete.

In Figure 4a, the between the tips 2b and 3a, there is shown at the same time an applied chuck 6 with the jaws 6a clamped workpiece 10th The workpiece has a shaft-side shaft end 10a, cylindrical sections 10b, which are delimited by flat sides, and the profile sections 10c. On a ground steady rest 25, a bezel 26 is employed to support the relatively long wave-shaped workpiece. The chuck 6 with the inner centering 2b is mounted on the workpiece spindle 2a of the workpiece spindle head. 2 If - as shown in Figure 4A - the profile portion 10c is ground by the grinding wheel 21, the clamping device 6 remains tensioned with their clamping jaws 6a at the shaft end of the shaft 10a. In order to grind the corresponding profile sections, the grinding wheel 21 on its grinding spindle head and not shown, the 21 supporting Schleifspindei about the two axes X2 and Z2 corresponding to the geometrical shape of the profile section deliverable on the wheel head, the grinding wheel.

The tailstock 3 is a Andrucksteuerung 30 is shown, by means of which the axial thrust of the tailstock tip 3a is adjustable to the arranged at the front end of the workpiece center preselected in the CNC control. This axial pressure is used to secure the clamping forces during the grinding process. To relax the tailstock tip 3a is provided free of pressure in its associated center of the workpiece 10, and consequently made the workpiece with respect to its stress-free clamping.

Figure 4B shows a partial view in direction A of the workpiece which corresponds to the slip state shown in Figure 4A, during the grinding of its tread portion.

The tension situation shown in Figure 4B corresponds to that of FIG 4A. According to this partial view of the workpiece 10 is ground on the straight profile portion 10c. The adjustment axes A2, Y2 and Z2 are represented by respective double arrows. The workpiece is displayed in the foreground as held between the tips 2b and 3a. The grinding wheel 21 for grinding the tread portion 10c with respect to the plane of the drawing of FIG 4B behind the workpiece and with its grinding spindle 22 inclined so that the inclined Geradnuten can be ground in the profile portion 10c by an appropriate interpolating operation between the axes Z2 and C.

In Figure 4C the grinding situation is now related as shown in FIG 4B, on the section plane BB. On the workpiece 10, the profile section 10c is in the form of a toothing or circumferential moderately distributed more extending in the longitudinal direction of the workpiece grooves shown. The grinding wheel 21 is picked up by its grinding spindle 22 and in the oblique supply angle of the oblique toothing CNC-controlled via the A2 axis swiveled. Schematically, the C, Y2 and X2-axis are represented by respective double arrows. Depending on requirements, a profile portion may also be ground with curved grooves as with screw rotors with the inventive method. Figure 5 shows a partial plan view according to Figure 3 during finish grinding of the cylindrical portions and the flat sides of the workpiece in accordance with the inventive method. The basic structure corresponds to that according to Figure 3, so that this basic structure is not performed here again.

The basic principle is that during the operations performed grinding operation, the workpiece remains clamped, but after this the clamping is released, so that internal stresses may be released in the workpiece, and a stress-free state of the workpiece can be ensured for subsequent grinding operations. The finish grinding of the person concerned the sections takes place in the illustrated according to FIG 5 version after the rough grinding method with inclined grinding wheel 1 1. It is also possible in principle that the grinding of these sections can also be carried out with inclined grinding wheel 11 so as to be inserted several times. In this case, the cylindrical portions to be ground piercing grinding method in Schrägein-. After the cylindrical portions WOR finish ground to are, in turn takes place a relaxation of the workpiece 10, that is, after this grinding operation, the clamping of the workpiece 10 is released to its relaxation, in such a way that the jaws 6a of the chuck dissolved 6 and the tailstock 3a rests in the center of the shaft portion 10 only without pressure. Characterized the workpiece is no longer excited, so that during grinding the freige- liberated or generated internal stresses are set, and a present internal stress-free machining condition for the workpiece upon renewed grinding.

6 shows a side view of the region of the grinding machine is shown, in which the workpiece is clamped, namely 10c during grinding of the tread portion in accordance with the ER inventive method.

The basic structure and the manner in grinding or between individual grinding operations corresponding to the above-described with respect to particular figures 3 and 5, so that this basic structure will not be described again. According to Figure 6 the finished grinding is carried 10c of the profile section. The profile portion 10c is formed in the present example, as a helical toothing, said loops having an electroplated or vitrified bond grindstone 21 occurs. A vitrified bonded grinding wheel may preferably be used to grind fertigzu- the tread portion 10c. The finish grinding is carried out in known manner by an interpolating procedural the various CNC-controlled axes for the second grinding wheel 21. It will be understood that to achieve a very high accuracy, the electroplated grinding discs 21 have a very high accuracy for the Fertigschieifen have to. In INTENT of vitrified bonded grinding wheels 21, these are provided by dressing with the required profile. This latter operation is not necessary, provided that the required accuracy can be achieved on the finished workpiece 10 already previously described Vorschleifvor- transition for the tread portion. In such a case it would in the ren Figu- 4A, B, C described roughing equal to the finish grinding operation. After the finish grinding operation of the tread portion is finished 10c, the chucking of the workpiece is released and removed selbiges with an appropriate handling system of the machine.

And finally 7 by way of example wave-like workpieces are drawn in figure, which can be ground using the inventive method. This wave-shaped workpieces have cylindrical portions, as well as profile sections. This is a gear shaft 27a, a further transmission shaft 27b, the latter having three profile portions, as well as two rotor shafts 28/29 for compressors, blowers or vacuum pumps displacement pumps. From these only exemplified undulating components with profile sections it is clear that it is highly complex ground surface designs for these components, which also require a very high manufacturing precision because these waves rolling at exactly matching crests and the respective flanks. When the waves shown for compressors or positive displacement pumps must be used, the requirements are even higher because in addition to the simple rolling of a sealing function in the profiles when combing two mutually crafted such WEL is lenzu guarantee.

Surprisingly, it has been shown that the grinding complete machining of such relatively complex designed wave-like workpieces processing one during the entire loading now undissolved clamping to achieve improved dimensions, position and shape accuracy just does not require.

LIST OF REFERENCE NUMBERS

1 machine stand

2 Workhead

2a workpiece spindle

2b Workhead tip

3 tailstock

3a tailstock

4 clamping and rotation axis

5 first wheelhead

6 chuck

6a clamping jaws

8 first dressing spindle

9 first grinding spindle

10 workpiece / shaft part

10a shaft-side shaft end

10b cylindrical portion

10c profile section

11 first grinding wheel

12 pivot axis (A axis)

13 pivot axis (B-axis)

14 means for changing the grinding disc

15 Implementation robot

16 gripper unit

17 cooling nozzle set

18 cabinet

19 vertical guideways

20 second wheelhead

21 second grinding wheel

22 second grinding spindle

23 second dressing spindle

24 coolant / lubricant hoses

25 steadyrest

26 bezel

Gear shaft 27a

27b gear shaft rotor shaft for compressors, blowers, vacuum pumps etc. rotor shaft for displacement

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