Patent Application
20140144301
This invention relates to a method for reprofiling wheelsets rotatably mounted in axle bearing housings on rail vehicles on underfloor wheelset lathes equipped with machining tools, a machine control for the machining tools, drive rollers, axial guide rollers, measuring rollers as well as clamping devices to engage the axle bearing housings.
EP 0 201 619 B1 describes a method for correcting the profile of a railway wheel in a material-saving way using a machining process. This well-known method is used when areas of the profile deviate from a nominal profile due to material wear on the running surface and/or wheel flange, it is characterised by the fact that profile areas with lesser wear are detected, whereupon these are subjected to a forming process, displacing material from the profile areas which flows into deeper-lying areas and at least partially fills the most worn areas with material before the radial position of a corrected profile is determined, which is produced by the cutting process and is offset radially outwards with respect to the wear profile. Hence, the application of this method presupposes that the worn wheel flange is subjected to a forming operation such as rolling or forging, and that thereby material is removed from the tip of the round edge of the wheel flange so that the amount of material that is displaced to the flange peak, thereby increasing the thickness of the wheel flange, is shifted towards the running surface. From this reference to the state of the art, it is apparent to an expert that the reprofiling of railway wheelsets can be performed only on machines which do not belong into the category of underfloor lathes. It would, therefore, seem to be impossible that the method disclosed in EP 0 201 619 B1 could be applied to underfloor wheelset lathes.
DE 10 2006 054 437 A1 describes a method for reprofiling a railway wheel belonging to a railway wheelset by machining. This method is characterised by limiting reprofiling to the removal of instances of out-of-roundness in a first, central area to both sides of the measuring circle plane of the railway wheel; in a second area extending from the outer edge of the profile to the central area, the nominal contour is restored, and in a third area extending from the middle section up to the wheel flange, reprofiling is limited to the removal of a layer close to the surface. Although this method is somewhat more suitable to be applied to underfloor wheelset lathes, there is nevertheless no indication in this principle according to DE 10 2006 054 437 A1 as to how highly accurate reprofiling can be carried out on an underfloor wheelset lathe.
However, highly accurate reprofiling of a wheelset is the prerequisite before such a wheelset can be used on high-speed vehicles. It is characteristic of the wear pattern of a wheelset for use in high-speed ranges that in the initial stage material will be rolled out in the area of the measuring circle plane and shifted equally to the wheel flange side and to the outer side of the wheel tyre.
This insight gives rise to the purpose of the present invention; namely, to propose a method in which the mileage of the wheelsets can be significantly increased with a minimal removal of material. According to the method to be created, it should in particular be possible to reprofile the wheelsets of high-speed vehicles. As such, a wheel to be reprofiled is to be machined on an underfloor wheelset lathe in a single cut with a cutting depth of between 0.1 mm to 0.2 mm. In doing so, the maximum deviation from the nominal diameter should not exceed a value of 0.1 mm. The highly accurate reprofiling on an underfloor wheelset lathe should also increase cost-effectiveness, since the wheelset does not need to be removed from the vehicle in order to be reprofiled.
This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.
According to the invention, this function is achieved by:
In an advantageous embodiment of the method, it is intended that the drive rollers be subjected to an additional force between 20 kN and 50 kN, preferably 30 kN for each drive roller. Thus, a particularly rigid clamping of the wheelset on the underfloor wheelset lathe is achieved.
According to a further advantageous embodiment, there is provision for the machining allowance to be selected between 0.10 mm and 0.25 mm, preferably 0.15 mm. Such a feed is useful for eliminating surface damage of the reprofiled profile by fine cracks.
A restoration of the profile is preferably performed by only a single machining cut. In this case, the procedure is as follows:
The machining is carried out from the outer side of the wheel towards the measuring circle plane, that is, in the first third of the actual profile, with a cutting depth of between 2 mm and 6 mm, preferably 4 mm. In the area of the measuring circle plane, that is in the area of the running circle of the actual profile, the machining is carried out with a depth of between 0.10 mm and 0.25 mm, preferably 0.15 mm. Thereafter, in the area of wheel flange flank, the machining is carried out with a depth of between 0.0 mm and 4.0 mm, preferably 2.0 mm. Consequently, it is possible that no material is removed in the area of the wheel flange flank. Finally, at the round edge of the wheel flange, the machining is carried out with a depth of between 2.0 mm and 6.0 mm, preferably 4.0 mm.
With such different cutting depths, the passive cutting forces which influence the stiffness of the clamping and thus the accuracy of the nominal diameter of the restored profile also change. In this case, the “specific cutting force” is to be taken into consideration. The specific cutting force is that force that is required for machining a material with a machining cross section of 1 mm2. This force depends on the machinability of the material, the thickness of the chip taken off, the cutting speed and the cutting edge geometry of the cutting tool. The specific cutting force increases disproportionately with smaller chip thickness. This power increase has an impact on the accuracy of the profile to be produced. It is therefore important for the accurate machining of the wheel profile, the diameter and the concentricity, to ensure a rigid fixation; that is, clamping, of the wheel axle. It is also important to consider that the wheel axle remains mounted in axle bearing housings during machining on the underfloor wheelset lathe. The required bearing clearance must consequently be controlled in such a way that it does not enter into the machining result. This purpose is initially served by the fixation of the two wheels of the wheelset from the inner side by an axial guide roller which is brought into contact and then fixed on the inside of the wheel in its operative position. There is further provision for the axle bearing housings to be fixed by holding down with clamping lugs. However, the axle bearing housings can also be fixed with a support. Finally, there is also provision for the axle bearing housings be fixed by both holding down and fixing with a support.
By using this method, it becomes possible considerably to increase the mileage of wheelsets by removing a bare minimum of material. In this way, the wheelsets of high-speed vehicles in particular can be economically reprofiled.
The invention is described in detail below using a sample embodiment. A simplified depiction that is mostly schematic can be seen in the following figures:
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
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.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
The wheelset 1 shown in
For reprofiling it is necessary to eliminate the actual profile 8 and restore a nominal profile 11 that meets the requirements of the reprofiling of the wheelset 1. In this case, the underfloor wheelset lathe is equipped with a measuring roller 13 to determine the actual profile 8, and this is also used to confirm the work result by checking the restored nominal profile 11. The results obtained from the measuring roller 13 are entered into the machine control (not shown), in which case the measurement results from the left wheel disc 4 and the right wheel disc 3 can be compared with each other and then the smaller of the actual diameters of the two wheel discs 3; 4 minus a machining allowance of, for example, 2×0.15 mm is entered as the target diameter. This allowance of 0.15 mm is necessary to rule out residual damage to the nominal profile 11, which can be formed by material displacement in the form of minute cracks. In
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
This application is a 371 U.S. National phase of PCT/DE2010/001399, filed on Nov. 26, 2010. The entire disclosure of the above application is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DE2010/001399 | 11/26/2010 | WO | 00 | 11/7/2013 |
