• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a method for machining a workpiece, preferably cylindrical wheels with involute teeth (20) with a multi-start grinding worm. In the first step, the workpiece is ground with the multi-start grinding worm in the event that the number of workpiece teeth and the number of tool passes is an integer. In a second step, the pitch (p) of the workpiece is measured and in a third step the pitch measurement result is assigned to the respective worm gear. In a fourth step, the dressing tool is delivered in accordance with the pitch measurement result in order to dress the grinding tool again in a fifth step. The steps are carried out until the graduation measurement result meets the tolerance requirements.
    公开号:CH710569B1
    申请号:CH01531/15
    申请日:2015-10-21
    公开日:2020-06-30
    发明作者:Geiser Hansjörg
    申请人:Liebherr Verzahntech Gmbh；
    IPC主号:
    专利说明:

    The invention relates to a method for machining a workpiece, preferably cylindrical wheels with involute teeth, with a multi-start grinding worm.
    When grinding gears with a multi-start grinding worm in the hobbing process, the geometry of the grinding worm is essentially determined by the toothing to be ground. The grinding performance is significantly influenced by the diameter of the grinding worm and its number of gears. Thanks to high-precision and rigid NC drives, multi-speed grinding worms can be used effectively and with ever smaller numbers of teeth and within narrow tolerances. However, the mechanical load on the tool and the dynamics of the tooth engagement increase, so that ultimately the increase in the number of gears brings an increase in performance, but at the expense of the workpiece quality and tool downtime.
    Another point that has to be taken into account when selecting the grinding worm relates to the determination of the number of gears with regard to the divisibility of workpiece number of teeth to number of tool gears. If possible, a rising ratio should be avoided here, since otherwise the gear pitch error of the grinding worm affects the pitch accuracy of the workpiece when the number of teeth ratio increases.
    On the other hand, the choice of a non-rising number of teeth ratio is also not entirely unproblematic, since gear pitch errors in the tool are shown as feed marks in the flank line. While these marks are only a few micrometers in size, even with very narrow tolerance specifications, the teeth can no longer be ground to tolerance.
    Due to the ever increasing demands on the workpiece quality, an ever greater effort must be made in the manufacture of gears in order to achieve the required quality. In addition, the number of tool types for a large number of workpieces to be manufactured should be reduced as far as possible. This would be a desirable method for the user, in which it is no longer necessary to pay attention to an optimized ratio of the number of teeth for each workpiece, without the required workpiece quality having to suffer as a result.
    [0006] DE 10 2012 005228 A describes a method for grinding a gearwheel by means of a multi-start machining tool, in which an increased quality of machining is possible, especially with an unfavorable gear ratio. In order to achieve a high division accuracy, the workpieces are ground in a two-stage process.<tb> • <SEP> First, the workpiece is ground in a first partial grinding process using a multi-start tool, the processing tool being fed into a first gap in the workpiece to be machined.<tb> • <SEP> In a second partial grinding process, the same workpiece is ground again, this time the tool is fed into a second gap that differs from the first gap. In total, at least two partial grinding processes are required to complete the workpiece. A particularly positive grinding result is achieved above all if the second partial grinding process is carried out with little or even no infeed. A disadvantage of this method is that the grinding process is extended by a further process step. This is particularly important in large series production.
    DE 43 39 041 A describes a dressing tool for double-thread cylindrical grinding worms. This dressing tool is constructed in several parts and can be adjusted by adjusting individual dressing disks or halves of the dressing disks by adjusting the distance between the dressing surfaces using screws and ground spacers. Disadvantages are the complex assembly / disassembly and the precision of the setting on the machine.
    In practice, it is required to make corrections of the order of less than 1/1000 mm. However, this cannot be achieved with the solution described above, or only with great effort.
    The object of the present invention is to provide a grinding process with multi-start grinding tools and the associated dressing tool, with which the required surface quality can be generated in a simple manner on the flanks of a toothing machined therewith.
    According to the invention this object is achieved by a method with the features of claim 1 or claim 2. Advantageous refinements and developments of the invention are described in the dependent claims.
    [0011] The method according to the invention according to claim 1 has the following steps:<tb> • <SEP> Machining the workpiece with the multi-start machining tool.<tb> • <SEP> Measurement of the individual pitch deviation fp separately for the right and left flanks of the toothing.<tb> • <SEP> Correction of the movement of the dressing tool relative to the grinding worm in the axial direction of the tool as a function of the individual pitch deviation determined for each tool pass and possibly as a function of the tool width position. Alternatively, in the case of multi-start dressing tools, the dressing tool can also be readjusted or reworked according to the measurement result.<tb> • <SEP> With the corrected dressing tool, the grinding worm is now dressed again and then another workpiece is ground. On this, the individual pitch deviation fp is measured separately for the right and left flanks and, if necessary, the dresser position is corrected in relation to the grinding tool or the dresser. The steps are repeated until the desired divisional deviation fp corresponds to the tolerance specifications for the workpieces.<tb> • <SEP> Then series production is started with the original workpieces.
    According to a preferred embodiment for gears in which there is a non-integer ratio between the number of workpiece teeth and the number of tool passes, a replacement toothing with an integer ratio is manufactured as an upstream step. If, for example, the original toothing has 17 teeth, a replacement toothing with 18 teeth is produced, which can then be processed, for example, with a 6-speed worm. The replacement toothing is then machined instead of the original workpiece.
    According to the invention, it is no longer important because of the optimized dresser whether an integer tooth ratio is present.
    According to the independent claim 2, there is an alternative method according to the invention with a non-integer ratio between the original number of workpiece teeth and the number of gears of the tool in order to minimize the pitch error on the workpiece. Here, an additional second cut with a low infeed (for example 0.005 mm) and a very high axial feed is carried out. This means that each flight of the grinding worm cuts a groove in the tooth flank. In between, there must always be an area of the previously perfectly polished flanks, which serves as a reference value for determining the pitch deviation for the individual gears. In the deeper grooves created by the individual gears, you can now see whether one or more tool paths are particularly prominent and can then correct this gear / gears accordingly. After this second cut, the fourth step continues according to the above procedure.
    [0015] The methods initially sound quite complex. However, if you take into account that this usually only has to be carried out once for a new multi-speed dressing tool or for the start of series production for a new gear series, the effort is put into perspective if you get significantly better workpieces in large series. If necessary, random checks can also be carried out during the series. If the result of the sample then deviates from the specifications, the corrections can be carried out with little effort on the basis of the knowledge gained from the initial installation or initial adjustment.
    The correction of the dresser takes place depending on whether it is a dresser for a single worm gear or a multi-start dresser.
    If the dresser serves to dress only one gear, an offset value can be determined by the control when the position for the next gear is approached. This value can also vary depending on the screw width position and the respective gear.
    However, if it is a multi-course dresser, the dressing tool can either be corrected by an additional dressing disc that is clamped in the machine. Alternatively or if the correction amounts are too large, the dressing tool must be reworked outside the machine.
    An expedient embodiment of the inventive concept provides that the gear cutting machine has a suitable control function for the application of the method, which supports the user accordingly. This can be done, for example, by automatically determining and outputting correction specifications for the dressing tool from the division measurement that has taken place. If the graduation measurement and correction of the dresser takes place within the machine, the modifications can be carried out in a user-guided manner by the control.
    Therefore, the pitch measurement is carried out as possible within the gear cutting machine, since then the assignment of the machined workpiece gap to the grinding worm gear is relatively simple as long as the workpiece is still clamped and thus the rolling coupling is not yet released. Alternatively, the gear cutting machine can also stop the workpiece and the tool in a defined position, so that the machine operator can mark the workpiece accordingly and the assignment of the pitch measurement to the tool path is also given in the event that the workpiece is measured on an external measuring machine. The machine control can also provide appropriate support here.
    Another strategy of assigning the measurement results on the workpiece to the gear pitch error of the grinding worm or the dresser is to first modify a gear by a larger amount in a targeted manner. This is clearly evident in the grinding result, especially when the method is used in which the workpiece was ground again in the second cut with increased feed. This means that the other gears can also be assigned and can be corrected together with the more modified gear after the measuring teeth on the gearwheel.
    With the method according to the invention, a high division accuracy is achieved in order to improve the smooth running of the gear pair machined in this way and thus produce low-noise gears.
    Further features, advantages and properties of the invention are explained in more detail below with reference to several exemplary embodiments shown in the drawing. Show it:<tb> Fig. 1: <SEP> a grinding worm with a dresser in the form of a profile roll,<tb> Fig. 2: <SEP> a grinding worm with a full profile dresser,<tb> Fig. 3: <SEP> an end cut through a workpiece profile,<tb> Fig. 4: <SEP> a measurement report of an individual pitch deviation fp for a flank, ground with a multi-start tool with pitch error, the relationship between the number of workpiece teeth and the number of gears of the tool not working,<tb> Fig. 5: <SEP> a measurement report of an individual pitch deviation fp for a flank, ground with a multi-start tool with pitch error, the ratio between the number of workpiece teeth and number of gears of the tool being an integer,<tb> Fig. 6: <SEP> a measurement report of an individual pitch deviation fp for a flank ground with a multi-start tool with pitch error, the ratio between the number of workpiece teeth and number of gears of the tool being an integer and the dresser having been corrected using the method according to the invention and<tb> Fig. 7: <SEP> a partial view of a toothing that was processed with the method according to the invention in order to determine the pitch error on the dresser and the associated correction amount.
    Figure 1 shows a known profile roller set 13 for dressing a grinding worm 10 (here shown a 2-speed grinding worm). The dresser consists of a flank dresser 12 (double cone dresser) and a head dressing roller 11, with which either the left and right flanks of a worm gear and the associated tip radius are dressed. In a second pass, the counter flank and the other tip radius are dressed.
    In the case of multi-start tools, this is initially carried out for one worm gear over the entire worm width. The dressing tool is then shifted one gear back into engagement so that the second worm gear can also be dressed. The number of dressing passes is proportional to the number of passes of the tool. The advantage of this dressing concept lies in its flexibility. By swiveling the dresser about an axis transversely to the tool axis, corrections, for example pressure angle corrections, can be generated on the grinding tool. This dressing concept is also available as a two-flank dresser in which the right and left flanks of a worm gear are dressed at the same time and the dressing cycles can thus be carried out more quickly. In this embodiment, the head dressing roller is also partially dispensed with. In this case, the head of the grinding worm is modified using a fixed dresser.
    A further reduction in the time for the dressing cycle can be achieved in a known manner with the full profile roller 14 shown in FIG. 2 for dressing a grinding worm 10. Solid profile dressing rolls are often used for dressing multi-start grinding worms for generating grinding of small-module gearwheels. The profile of the dressing roller corresponds exactly to the grinding worm profile. This means that a grinding worm can be dressed completely with just a few dressing runs, depending on the dressing width in relation to the screw width.
    [0027] The time for dressing a grinding worm is thus significantly reduced. However, this affects the dressing flexibility, since only the dressing profile can be transferred exactly to the grinding worm. If changes to the grinding worm profile are required, the dresser must be reworked. However, this is a proven method for the large-scale production of gear wheels.
    The problem underlying the invention can be explained with reference to FIG. FIG. 3 schematically shows an end section of a toothing 20. The division p shown in the end section is defined as the length of the partial arc between two successive right or left flanks. In practice, the distances between the flanks aligned in the middle of the profile are measured. The deviations are linearly converted to the pitch circle. Certain parameters such as e.g. the divisional deviation can be calculated fp. This designates the difference between the actual dimension and the nominal dimension of a single front division of the right or left flanks. On a gearwheel with z teeth, there are z individual deviations of the right and left flanks. The deviation is the difference between the individual measured values and the mean of all z measured values. Too large a distance is recorded between teeth 1 and 2. This means that the left flank of tooth 2 is further away from the left flank of tooth 1 than the mean. The tooth gap 2 is therefore too large. An example with too small a distance is shown between teeth 3 and 4. The smaller the fluctuation of these distance values, the smoother the gearing with their counter gear.
    The following FIGS. 4 and 5 show evaluation diagrams 30, 31 for individual pitch deviations 33 for a flank on different toothings that have been processed with different tools. It shows how a multi-start tool with pitch error between the tool steps, with different ratios between the number of steps of the tool and the number of teeth on the workpiece, is represented in the individual pitch deviation. The individual pitch deviation compared to the mean value 32 of the tooth pitches on the workpiece is shown.
    FIG. 4 shows a measurement result 30 of a divisional individual deviation for a 6-course tool with which a workpiece with 17 teeth was produced. In this case, the number of teeth ratio does not work and a pitch error on the tool has only a minor effect on the pitch measurement, since there is a constant change of tool paths between the individual workpiece teeth during machining.
    Comparing this to FIG. 5, in which a workpiece with 18 teeth was machined with the identical tool, the gears can be identified on the basis of the pitch errors in measurement log 31. The error in the tool path that processed the fourth tooth gap is particularly outstanding. Here the divisional individual deviation is too small compared to the mean value of all measured values. The next divisional individual deviation over the tooth gap 5 is too large. This suggests that the distance between the tool passages that worked the tooth gap 3 and 4 is too small. The tool can be corrected during dressing by assigning the record of which workpiece tooth was ground with which tool path and the value measured here.
    Depending on the type of dressing tool used, either the controller must move the position of the dressing disk when dressing this worm gear by the measured value as an offset in the axial direction of the tool. Alternatively, this gear must be corrected for a multi-speed dressing tool.
    This can now either be done on the gear cutting machine by reworking the dresser with the help of a second processing tool or by reworking the tool on an external machine.
    It may also be necessary to correct both the dresser position and the dresser, since it is possible, for example with a 3-speed dresser in addition to a 3-speed grinding worm, to dress one with 6, 9 or even more gears. In this case a combination of the corrections may be necessary.
    FIG. 6 shows the measurement result 34 for a workpiece according to FIG. 5 which was processed with a grinding tool which had previously been processed with a post-corrected dresser. In this case, only the worm gear that corrects the fourth tooth gap was corrected in order to make the effect of the invention clear. If the division accuracy achieved is not sufficient, the method according to the invention can also be carried out for the other worm threads.
    The method described here for a grinding worm can of course also be transferred to other gear-coupled working / machining / hard machining processes in which a specific workpiece tooth can be assigned exactly to a defined tool tooth / gear during machining and in which it can be assigned to one certain accuracy arrives. This method would be conceivable, for example, in skiving, skiving, but also in gear honing or gear butting.
    FIG. 7 now shows a schematic partial view 40 of a toothing which was machined on one flank (left flank = LF) with the method according to the invention using a 3-course tool in order to determine the pitch error on the dresser and the associated correction amount. For this purpose, the workpiece was first machined in a first step with the machining parameters optimized for this toothing. In a second process step, another grinding pass with a low infeed but significantly increased feed of the tool was ground in the axial direction of the toothing. The individual gears 41, 42, 43 of the grinding tool and their deviation can be identified and determined by this procedure. If a gear 43 was additionally modified in preparation for the multi-speed grinding worm, this can be clearly identified by the grinding result. Between the markings on the flank of the ground toothing there are surfaces 44 which, due to the high axial feed of the tool, have not been machined in this grinding cycle. The depth of the feed markings (shown here exaggerated) compared to the non-machined surfaces 44 and the difference between the individual gears, together with the knowledge of the value by which the tool was delivered radially, gives the information, the amount and in which direction the gears of the Grinding worm need to be corrected. The necessary corrections on the dresser can also be calculated from this.
    权利要求:
    Claims (7)
    [1]
    1.Method for machining a workpiece with a multi-start grinding worm, the workpiece being ground with the multi-start grinding worm in a first step in the event that there is an integer ratio between the number of teeth on the workpiece and the number of gears of the multi-start grinding worm second step this workpiece is measured with regard to its division, in a third step the division measurement result is assigned to the respective worm gear, in a fourth step an associated dressing tool is adjusted and / or modified according to the division measurement result and in which the grinding worm is dressed again in a fifth step , whereby the correction cycle is carried out iteratively until the graduation measurement result meets the tolerance requirements.
    [2]
    2.Method for machining a workpiece with a multi-start grinding worm, the workpiece being produced with a modified number of teeth in the event that there is a non-integer ratio between the number of teeth of the workpiece and the number of flights of the multi-start grinding worm, the number of teeth of the Replacement workpiece is selected so that the number of teeth ratio is now an integral number, in a first step grinding with the multi-start grinding worm, in a second step this workpiece is measured for its pitch, in a third step the pitch measurement result is assigned to the respective worm gear, in a fourth step Step an associated dressing tool is delivered and / or modified in accordance with the division measurement result and in which the grinding worm is dressed again in a fifth step, the correction cycle being carried out iteratively until the division measurement set bnis meets the tolerance requirements.
    [3]
    3. The method according to claim 2, characterized in that after the first processing step with the grinding worm, a further processing step is carried out with the grinding worm, in which the workpiece is machined with a low infeed and a very large axial feed, the axial feed being chosen so large that each flight of the grinding worm cuts a groove in the tooth flank, leaving an area between the grooves that was created by the first machining step, which makes it possible to check whether the groove depth in the tooth flank in relation to the flank surface after the first cut the individual gears of the grinding worm are cut to the same depth, and as a result it is possible to calculate a correction value for the correction of the dresser from a possibly resulting difference in the individual groove depths.
    [4]
    4. The method according to any one of claims 1-3, characterized in that the catchable dressing tool receives an offset position in the direction of the tool axis when dressing a further worm gear different from the previously trained worm gear, which is determined by a machine controller from the pitch measurement result, this can be different over the tool width position.
    [5]
    5. The method according to any one of claims 1-3, characterized in that the dressing tool, in particular a multi-course dressing tool, is corrected on the gear cutting machine by reworking its surface in accordance with the pitch measurement results.
    [6]
    6. The method according to any one of claims 1-3, characterized in that the dressing tool, in particular a multi-course dressing tool, is corrected on a separate machine tool by reworking its surface in accordance with the graduation measurement results.
    [7]
    7. Gear cutting machine for performing the method according to one of claims 1 to 3 with a device for measuring the pitch of machined workpieces, a multi-start grinding worm and a dressing tool.
    类似技术:
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    EP0278512B1|1990-07-04|Method for the machining of gears
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    DE3533064A1|1987-03-26|METHOD FOR MACHINING THE FLANGES OF GEARS THROUGH ROLLING SHELLS AND DEVICE FOR IMPLEMENTING SUCH A METHOD
    WO2007031219A1|2007-03-22|Tool arrangement for the production of helical teeth in gear wheels
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    EP2929970B1|2019-11-06|Method for grinding of a workpiece with a grinding worm
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    EP3326753B1|2022-01-12|Method of dressing a grinding worm by means of a dressing tool
    WO2012097984A1|2012-07-26|Method for milling a worm gear and apparatus therefor
    DE102005035576A1|2007-02-01|Production of threads for drill strings comprises mechanically producing a radial oscillation movement between a rotating tool and the workpiece
    WO1994020238A1|1994-09-15|Tool and method for the non-cutting manufacture of the outer teeth of gearwheels
    CH709263A2|2015-08-28|Tool for producing a thread.
    WO2015043752A1|2015-04-02|Method for producing a transmission control gear by means of a forming process
    DE102019128100A1|2021-04-22|Process for grinding the toothing or the profile of a workpiece
    同族专利:
    公开号 | 公开日
    DE102014019553A1|2016-06-23|
    CH710569A2|2016-06-30|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    DD236691A1|1985-04-30|1986-06-18|Zahnradwerk Pritzwalk Veb|PROCESS FOR PROFILE CONTROL OF ALIGNED GRINDING WHEELS FOR SMALL MODULAR TOOTHING|
    CH686171A5|1992-12-10|1996-01-31|Reishauer Ag|Dressing tool for dressing branch {ngiger, cylindrical grinding worms.|
    DE10220513B4|2002-05-08|2004-04-15|Gleason-Pfauter Maschinenfabrik Gmbh|Process for dressing or profiling a cylindrical or essentially cylindrical grinding worm|
    DE102012005228B4|2012-03-15|2013-11-21|Kapp Gmbh|Method for machining a workpiece with a worm-shaped machining tool|
    DE102012015846A1|2012-04-17|2013-10-17|Liebherr-Verzahntechnik Gmbh|Method and device for hard finishing of modified gears|CN109365924B|2018-12-24|2019-08-30|重庆市计量质量检测研究院|The more ball magnetic orientation formula tooth pitch templates of multilayer-and its magnetic force design method|
    法律状态:
    2020-09-30| PFA| Name/firm changed|Owner name: LIEBHERR-VERZAHNTECHNIK GMBH, DE Free format text: FORMER OWNER: LIEBHERR-VERZAHNTECHNIK GMBH, DE |
    2021-05-31| PL| Patent ceased|
    优先权:
    申请号 | 申请日 | 专利标题
    DE102014019553.8A|DE102014019553A1|2014-12-23|2014-12-23|Method for processing a workpiece with a multi-start grinding worm and dressing method|
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