Abstract:
The invention relates to a machine, in particular a machine tool ( 9 ) for deep rolling wheelset shafts ( 5 ) for rail vehicle wheelsets with a headstock ( 12 ) and a tailstock ( 13 ) which each have prick punch points ( 16 ) for holding a wheelset shaft ( 5 ) at its respective ends, a device ( 16, 18, 20, 21  and  22 ) for driving the wheelset shaft ( 5 ), as well as tools which can be moved in directions (z, x) on the machine tool ( 9 ) for deep rolling lengthwise sections (axle zones  1  to  4 ) of the wheelset shaft ( 5 ), and clamping and feed devices. The tools consist of several pairs of work rollers ( 14, 15, 23, 25, 24, 26 ), of which each pair is intended for deep rolling at least one axle zone ( 1, 2, 3, 4 ) of the wheelset shaft ( 5 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a National State application of PCT international application PCT/DE2010/000771, filed on Jul. 1, 2010, The contents of the application is incorporated by reference in its entirety. 
     FIELD 
     The invention relates to a machine, in particular a machine tool, for deep rolling wheelset shafts for rail vehicle wheelsets with two prick punch points for holding a wheelset shaft at its respective ends, a device for driving the wheelset shaft, two pairs of crankshaft deep rolling tools, which can be moved in directions x, y and z of the machine tool for machining the axle journal for the wheelset shaft, and with clamping and feed devices for the crankshaft deep rolling tools. 
     BACKGROUND &amp; SUMMARY 
     A “stamping wheel for burnishing shaft parts, particularly the axle journal and wheelset fail-safes” is known from the German patent document no. 808 197. The working surface of the stamping wheel consists of one cylinder, to which, on the one hand, a large rounding for the large corner groove of the axle journal and, on the other hand, a small rounding for the small corner groove on the axle collar are connected. The axle for the stamping wheel is supposed to adopt a skewed position to the axle of the axle journal during the burnishing procedure and, when pressed into the axle journal at one position, create a long, drop-shaped imprint on the surface of the axle journal. 
     At the time the above-mentioned German patent was registered, deep rolling was called “burnishing”. A company brochure of the applicant from 1954 then shows a machine which can be used to deep roll the two axle journals on a wheelset from their respective outer ends. Only the axle journals of finished wheelsets were machined respectively. To do this, two pairs of work rollers were used which were each meshed simultaneously onto the axle journals for the wheelset. In those days, the wheelset was driven via a transmission belt, which was looped around one of the two wheel discs for the wheelset. With the known machine, the axle journals for the wheelset were rigidified to such an extent that, along with having an improved surface quality, they also had simultaneous higher strength, whereby hot axle boxes were able to be prevented on the one hand and axle journal breakage on the other. The known deep rolling operation therefore meant that internal stresses were introduced into the surface of the axle journal which led either to no cracks being produced or cracks that were already produced being able to be brought to a stop. The outcome was that an increase in the service life of the wheelset was achieved. 
     As well as the treatment of the axle journal, a “device for burnishing cylindrical workpieces like shaft parts” is already known from the German patent document no. 843 922. The known device features one or more work rollers, whereby each work roller is mounted in a pivoting carrier whose swivel axis runs both vertically to the infeed motion of the work roller and vertically, or nearly vertically, to the workpiece axis. The known device was supposed to be used mainly for machining cylindrical shafts, which does not rule out that it could be used for deep rolling wheelset shafts, too. 
     Damage to the wheelset shafts of railway high-speed vehicles which has recently occurred has led to particular attention being paid towards the finishing of the wheelset shafts. In doing so, the formation of cracks in particular is to be counteracted. 
     On the basis of the knowledge that by introducing residual compressive stresses into the surface of crankshafts, the formation of cracks can be prevented or cracks that have already occurred can be brought to a stop, the task of this invention is now to propose a modern machine which can be used to deep roll the wheelset shafts of wheelsets for railway vehicles before the wheel discs are fitted. As is well known, a wheelset shaft is characterised in that it features several adjacent lengthwise sections (hereinafter referred to as axle zones) with different diameters. 
     In a machine tool of the type specified, this invention means the task is solved by having tools that comprise more than two pairs of work rollers, of which each pair is intended for deep rolling at least one axle zone on the wheelset shaft. In a favoured variant, the tools comprise three pairs of work rollers. 
     Here, it is intended that the first pair of work rollers be used to deep roll the axle journals and transition piece, a second pair of work rollers to deep roll the press seating for one wheel disc and a third pair of work rollers to deep roll the stub shaft from the press seating at least up to the longitudinal centre of the wheelset shaft. 
     Ideally, the work rollers forming the first and second pair are each arranged together in one housing. This housing can be moved in the y-direction of the machine tool. Owing to the movability in the y-direction, the work rollers for the first and second pair of work rollers are meshed one after the other. At the same time, the housing can be pivoted around a B-axis of the machine tool. This movability makes it possible to machine the transitions between the individual axle zones of the wheelset shaft. As is well known, the transitions are arranged as corner grooves. 
     The first and the second pair of work rollers are at a specified fixed axial distance away from the third pair of work rollers in the z-direction of the machine tool. All three pairs of work rollers are ultimately arranged together on one slide. The common slide can be moved in the z-direction of the machine tool, i.e. in the feed direction. Two slides in total are provided on the machine tool, each of which is designated to the respective end of the wheelset shaft. When the axle zones are deep rolled, the two slides move towards each other at feed rate. 
     Ultimately, the crankshaft deep rolling tools can also be adjusted in the x-direction. A servo motor is used to feed in two work rollers, each forming one pair, in the direction of the wheelset shaft at the same time. Notably, all three pairs of work rollers are moved at the same time. The deep rolling force is also set via the infeed in the x-direction. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
       The invention is described in detail below using a design example. The following views are illustrated at a reduced scale: 
         FIG. 1  one half of a wheelset shaft in the side view, 
         FIG. 2  the basic structure of a machine for deep rolling wheelset shafts in a perspective plan view, 
         FIG. 3  the machining of the half of the wheelset shaft shown in  FIG. 1  with the aid of crankshaft deep rolling tools, 
         FIG. 4  the drive for a wheelset shaft in the sectional view, 
         FIG. 5  the longitudinal section through a tool slide with three different work rollers, 
         FIG. 6  a tool slide in a perspective view, 
         FIG. 7  a section from the tool slide in  FIG. 6  with a pair of work rollers, 
         FIG. 8  the holder for an individual work roller, 
         FIG. 9  the holder for two work rollers arranged vertically one above the other, 
         FIG. 10  a first version of a layout with work rollers, 
         FIG. 11  a second version of a layout with work rollers, and 
         FIG. 12  a third version of a layout with work rollers. 
     
    
    
     DETAILED DESCRIPTION 
     Wheelset shaft  5  on a wheelset (not shown) consists of several axle zones. Axle zone  1  represents the axle journal. Upon which the wheelset is rotatably mounted in the rail vehicle. In the direction towards the longitudinal centre  6  of the wheelset shaft  5 , axle zone  2  follows axle zone  1 . Axle zone  2  forms the transition between axle zone  2  and axle zone  3  and is formed through a corner groove  7 . Axle zone  3  forms the press seating for a wheel disc (not shown) of the wheelset. Axle zone  3  is followed by axle zone  4 , which is also referred to as the stub shaft, and has a considerably smaller diameter when compared with axle zone  3 . Axle zone  4  stretches up to the longitudinal centre  6  of the wheelset shaft  5 , upon which identical axle zones  4 , 3 , 2  and  1  follow to the other end (not shown) of the wheelset shaft  5 . 
     Axle zones  1  to  4  for the half of the wheelset shaft  5  shown are machined by the first slide  8  for the machine tool  9 , while the axle zones  4  to  1  on the other half (not shown) of the wheelset shaft  5  are worked on by a second slide  10  for the machine tool  9 . At the same time, the two slides  8  and  10  work towards each other in the direction of the longitudinal centre  6  of the wheelset shaft  5 , each starting from the axle zones  1 . 
     On machine bed  11  for machine tool  9 , one headstock  12  and one tailstock  13  are initially arranged so that they can be moved longitudinally in the z-direction. The first slide  8  is upstream of the headstock  12  in the z-direction, and the second slide  10  is upstream of the tailstock  13  and can also be moved in the z-direction. The two slides  8  and  10  can be moved in the z-direction at feed rate, independent of their respective headstock  12  or tailstock  13 . A second headstock, which is designed in exactly the same way as the headstock  12  shown, can also be provided in place of tailstock  13 . The design of headstock  12  will be dealt with in the following. 
       FIG. 3  shows the left half  11 ′ of the machine bed  11 . Clamped in headstock  12 , one can see the left half of the wheelset shaft  5  shown in  FIG. 1 . One also recognises the first slide  8  with work rollers  14  and  15  ( FIG. 12 ) for deep rolling axle zones  3  and  4 . 
     The headstock  12  shown in  FIG. 4  initially has a headstock drive lug  16 , which engages in the centring hole  17  of wheelset shaft  5 . The headstock drive lug  16  has a driver pin  18  which it uses to engage in an axial bore  19  of wheelset shaft  5 . Furthermore, the headstock drive lug  16  is fixed tightly to a pulley  20 , which is rotatably mounted via supports  21  in tailstock  13 . The pulley  20  is set in motion by a drive motor  22  via a belt drive (not shown) and moves the wheelset shaft  5  along with it via the headstock drive lug  16  and the driver pin  18  engaging in the wheelset shaft  5 . 
       FIG. 5  shows a longitudinal section in the z-direction through the second slide  10 . Here, one can see the two work rollers  23  and  24  arranged vertically one above the other, as well as work roller  15 . The two work rollers  23  and  24  are both rotatably mounted together in one housing  27 . Housing  27  can be moved in the vertical y-direction and the two work rollers  23  and  24  are at a fixed distance away from each other. Housing  27  can be moved up and down in the y-direction and can also be pivoted around a B-axis. A drive unit  28  is used for pivoting around the B-axis and for moving in the Y-direction. Together with its respective counter-rollers  25  or  26 , the work rollers  23  and  24  are provided in order to deep roll the axle zones  1  and  2  on the wheelset shaft  5 . 
     By contrast, the work roller  15  rotatably mounted in housing  37  in slide  10  is provided with a counter-roller  14  for the purpose of machining the axle zones  3  and  4  on wheelset shaft  5 . The work rollers  14 ,  15 ,  23  to  26  are not driven but are set in rotation by the driven wheelset shaft  5 . The drive units  28  and  29  are used to pivot the work rollers  23  and  24  or  25  and  26  around the B-axes. Two further drive units are used to move the work rollers  23 ,  24  or  25 ,  26  vertically in the y-direction,  FIG. 6 . The work rollers  23  and  25  form the first pair, the work rollers  24  and  26  the second and the work rollers  14  and  15  a third pair of work rollers. 
     A spindle drive  30 , which is specifically shown in  FIG. 7  once again, is provided for the infeed of the two drive units  28  and  29  in the x-direction towards the wheelset shaft  5 . The spindle drive  30  is initiated by drive motor  31  originating via belt drives  32  and  33 . All work rollers  14 ,  15  and  23  to  26  are fed in simultaneously in the x-direction. In addition, the spindle drive  30  moves the two carriers  34  and  35  with housings  27 ,  36  and  37 —where the work rollers  23  to  26  or  14  and  15  are each rotatably mounted—in the x-direction towards wheelset shaft  5  or away from there again once deep rolling has finished. With respect to the spindle drive  30 , the two carriers  34  and  35  are still each supported via the spring assemblies  38  and  39 . The spring assemblies  38  and  39  enable the work rollers  14 ,  15  and  23  to  26  to be in a position to follow irregularities in the roundness and in the shape of the wheelset shaft  5  on a limited basis. Ideally, spindle drive  30  is in the x-direction, which means it can move in this direction by up to 5 mm within the respective slide  8  to  10 . This makes is possible to compensate for any differences in the diameters of the work rollers  14 ,  15  and  23  to  26  without having to exert additional forces on the system. 
     In the machine&#39;s z-direction, the work rollers  14 ,  15 ,  23  to  26  for the two slides  8  and  10  each have a fixed distance  43  away from each other. This means that housing  27  and the carriers  34  and  35  each have specifically fixed lateral distances away from each other. As a consequence, spindle drive  30 , which is shown in  FIG. 7  for the movement of work rollers  14  and  15 , is also effective in the same way for the work rollers  23  and  24  or for their counter-rollers  25  and  26 . A central spindle  40 , which stretches over the longitudinal centre of the machine bed  11  and is set in rotation by a drive (not shown), is provided for the feed movement of the two slides  8  and  10  in the machine&#39;s z-direction. 
     At the start of the deep rolling operation, the work rollers  23  and  25  roll the axle zones  1  and  2 , whereby they are each pivoted around the B-axis for machining the corner groove  7  and the transition  41 . At the same time, the work rollers  14  and  15  roll the start  42  of axle zone  4 . After the axle zones  1  and  2  have been deep rolled, the work rollers  23  and  25  are disengaged by shifting in the vertical direction (y-direction) and the work rollers  24  and  26  become meshed. The work rollers  24  and  26  then roll the axle zone  3 , where the press seating is located between the wheelset shaft  5  and the wheel disc. At the same time, the work rollers  14  and  15  continue to machine axle zone  4  in the direction towards the longitudinal centre  6  of wheelset shaft  5 .