阅读说明：本技术 用于制造齿轮的方法、机床控制装置和机床 (Method for producing a gear, machine tool control device and machine tool ) 是由 K-M·里贝克 J·韦伯 于 2021-06-25 设计创作，主要内容包括：本发明涉及一种用于制造齿轮的方法,带有下列方法步骤：用制齿刀具(520)在单分度法中对多个齿轮(400)制齿,其中,制齿刀具(520)在所述多个齿轮(400)的每个齿轮(400)处通过切削加工制造了多个齿槽(413),针对所述多个齿轮(400)预定利用所述补偿参数的齿距补偿；由机床控制装置(540)根据制齿刀具(520)的磨损状态预定补偿参数。此外,本发明还涉及一种机床控制装置和机床。所述机床包括制齿刀具和机床控制装置。(The invention relates to a method for producing a gear, comprising the following method steps: -toothing a plurality of toothed wheels (400) in a single indexing process with a toothing tool (520), wherein the toothing tool (520) produces a plurality of tooth slots (413) by cutting machining at each toothed wheel (400) of the plurality of toothed wheels (400), wherein a pitch compensation using the compensation parameter is predetermined for the plurality of toothed wheels (400); the compensation parameters are predefined by the machine tool control device (540) as a function of the wear state of the tooth-forming tool (520). The invention also relates to a machine tool control device and a machine tool. The machine tool comprises a tooth making tool and a machine tool control device.)

1. A method for producing a gear wheel, comprising the following method steps:

-toothing a plurality of gears (400) in a single indexing process with a toothing tool (520),

-wherein the tooth making tool (520) makes a plurality of tooth slots (413) on each gear (400) of the plurality of gears (400) by cutting machining, and

-wherein a pitch compensation with a compensation parameter is predetermined for the plurality of gears (400);

it is characterized in that the preparation method is characterized in that,

-predetermining said compensation parameter by a machine tool control device (540) as a function of the wear state of the tooth-making tool (520).

2. The method of claim 1,

-predetermining a first compensation parameter for pitch compensation for a first wear state of the toothing tool (520),

-predetermining a second compensation parameter for pitch compensation for a second wear state of the toothing tool (520),

-the toothing tool (520) has less tool wear in a first wear state than in a second wear state, and

the first compensation parameter is different from the second compensation parameter.

3. The method of claim 2,

-performing a pitch compensation of a first part of the plurality of gears (400) with the first compensation parameter, and

-performing a pitch compensation of a second part of the plurality of gears (400) with the second compensation parameter.

4. The method according to claim 2 or 3,

-the second compensation parameter is automatically calculated by the machine tool control device (540) from the first compensation parameter,

-wherein a conversion formula is stored in the machine tool control device (540) for converting the first compensation parameter into the second compensation parameter.

5. The method according to any of the preceding claims,

-determining the number of gears (400) after the teeth have been made with the teeth making tool (520),

-wherein the number of gears (400) after the teeth making by the teeth making tool (520) represents the wear state of the teeth making tool (520).

6. The method according to any of the preceding claims,

-measuring the current consumption and/or the power consumption of a tool spindle drive (550) for rotationally driving the toothing tool (520),

-wherein a change in current consumption and/or power consumption represents a wear state of the tooth making tool (520).

7. The method according to any of the preceding claims,

-determining a pitch deviation of at least one gear (400) of the plurality of gears (400),

-in particular, the at least one gear (400) on which the pitch deviation is measured, one of the five last manufactured gears (400) of a part of the plurality of gears (400), and

-the part of the plurality of gears (400) comprises in particular twenty or more gears (400),

-wherein a pitch deviation represents a wear state of the tooth making tool (520).

8. The method of claim 7,

-performing a pitch measurement in a machine tool (500) with which also a toothing of the plurality of gears (400) with the toothing tool (520) is performed.

9. The method according to claim 7 or 8,

-taking a pitch measurement in a fixture in such a way that, whether the gear to be measured (400) is being toothed with the toothing tool (520) or the gear to be measured (400) is being measured, it is taken during clamping of the gear to be measured on a workpiece spindle (530) of the machine tool (500) and the gear to be measured (400) is not disengaged from the workpiece spindle (530) after toothing and before measurement.

10. The method according to any of the preceding claims,

-determining the wear status of the tooth making tool (520) by means of wear measurements on the cutting edges (522, 523) of the tooth making tool (520).

11. The method according to any of the preceding claims,

-the predetermination of the compensation parameter comprises the following method steps:

-reading the stored compensation parameters from a data memory of the machine tool control device (540).

12. A machine tool control device for manufacturing a gear is characterized in that,

the machine tool control device can acquire the wear state of the tooth making cutter;

the machine tool control device can predetermine a compensation parameter according to a wear state of the tooth-making tool (520) so as to predetermine a pitch compensation for the plurality of gears (400) using the compensation parameter.

13. The machine tool control device according to claim 12,

the machine tool control device can acquire a first wear state of the tooth-making tool and can predetermine a first compensation parameter for pitch compensation for the first wear state of the tooth-making tool (520),

the machine tool control device can acquire a second wear state of the tooth-making tool and can predetermine a second compensation parameter for pitch compensation for the second wear state of the tooth-making tool (520),

the tooth-making tool (520) has less tool wear in the first wear state than in the second wear state, and

the first compensation parameter is different from the second compensation parameter.

14. The machine tool control apparatus according to claim 12 or 13,

the machine tool control device (540) can automatically calculate a second compensation parameter from the first compensation parameter, wherein a conversion formula is stored in the machine tool control device (540) in order to convert the first compensation parameter into the second compensation parameter.

15. A machine tool for manufacturing gears, comprising:

a tooth forming tool (520) configured to form teeth of a plurality of gears (400) in a single indexing method, wherein the tooth forming tool (520) is capable of producing a plurality of tooth grooves (413) by cutting machining on each gear (400) of the plurality of gears (400),

machine tool control device, in particular according to claim 12, 13 or 14, configured for predetermining a compensation parameter as a function of a wear state of a tooth-making tool (520) in order to predetermine a pitch compensation for the plurality of gears (400) using the compensation parameter.

16. The machine tool of claim 15, further comprising:

a first sensor device configured to determine the number of gears (400) that have been formed with the teeth forming tool (520), wherein the number of gears (400) that have been formed with the teeth forming tool (520) represents a wear state of the teeth forming tool (520); and/or

A second sensor device, which is designed to measure the current and/or power consumption of a tool spindle drive (550) for rotationally driving the toothing tool (520), wherein a change in the current and/or power consumption represents a wear state of the toothing tool (520); and/or

A third sensor device configured to determine a pitch deviation of at least one gear (400) of the plurality of gears (400), wherein the pitch deviation represents a wear state of the teeth making tool (520); and/or

A fourth sensor device configured to measure wear on the cutting edges (522, 523) of the tooth-making tool (520) to determine a wear state of the tooth-making tool (520).

17. Machine tool according to claim 15 or 16, characterized in that a pitch measurement is performed in a machine tool (500) with which also the toothing of the plurality of gears (400) with the toothing tool (520) is performed.

Technical Field

The subject matter of the invention comprises a method for producing a gear, comprising the following method steps: the method comprises the steps of producing teeth of a plurality of gears in a single indexing method by using a tooth producing tool, wherein the tooth producing tool produces a plurality of tooth grooves on each of the plurality of gears through cutting machining, and pitch compensation using a compensation parameter is predetermined for the plurality of gears. The invention also relates to a machine tool control device and a machine tool.

Background

The continuous indexing method and the single indexing method differ in the context of the production of bevel gear teeth.

The continuous indexing method is characterized in that the gear to be machined performs a continuous indexing movement during the cutting process. This continuous indexing movement is coupled to the rotation of the tool or tool which effects the cutting process or the removal of chips, so that the tool performs a one-by-one cutting operation at successive tooth gaps (Zahnl ücke) on the gear to be machined. The gear to be machined is therefore rotated continuously and several times about its own axis during the continuous machining process or continuous chip removal until the tool produces a full tooth height on the gear. The tool is thus in continuous cutting contact with the gear to be machined.

In contrast to the continuous indexing method, in the single indexing method, one tooth slot is always produced completely by the tool, the gear is rotated one tooth pitch more and then the next tooth slot is milled in the same manner until all tooth slots have been produced. In the single-indexing method, the tooth grooves of the gear are thus machined in succession into the gear to be machined or into the tooth blank. In other words, this means that a first tooth slot of the gear is first produced by feeding the toothing tool and subsequently pulling the toothing tool back into the toothing blank before the toothing blank has been rotated by one tooth pitch, and that a second tooth slot is subsequently produced by feeding the toothing tool and subsequently pulling the toothing tool back into the toothing blank. The cutters are thus not in continuous cutting contact, but are re-fed again and again, tooth slot by tooth slot.

In both the single-indexing method and the continuous indexing method, the helically toothed bevel gears can be produced in a rolling manner, i.e. in a rolling process, or in a plunge manner, i.e. in a plunge milling process (Tauchverfahren).

Whereas in the rolling method the tooth spaces of the drive gear (Ritzel or pinion) and the driven gear (bellerrad or crown gear, bull gear) of a bevel gear pair are produced in each case during rolling, in the so-called forming or plunge-milling method the tooth spaces of the driven gear are produced only by plunge-milling with a rotating tool into the work piece which is not being rolled, while the drive gear grooves are produced in a specific rolling process with a tool inclined to the rolling axis. In plunge milling, the shape of the tool is transferred to the tooth flanks, which are formed by the envelope cutting of the cutting edges of the respective tool during the rolling process in which the tool and the workpiece move relative to one another according to a specific law.

The bevel gears can therefore be produced by rolling or plunge milling in the single-indexing method or by rolling or plunge milling in the continuous indexing method.

In the single-indexing method, in particular in the case of dry milling, i.e. in the case of soft teeth without cooling lubricant, the gear to be machined heats up to 50 ℃. The gear wheel is thus heated up to 30 ℃ during the cutting process from room temperature, for example 20 ℃, due to the cutting contact with the toothing tool. As a result of this heating, indexing or pitch deviations occur, since the gears expand as a result of the heat input. The circumferential graduation (or pitch or circumferential pitch) defines the distance between two adjacent left or right flanks of a tooth of the gearwheel, the pitch. In short, the indexing or pitch offset therefore describes whether the teeth of the gearwheel are in the correct position relative to the reference teeth of the gearwheel.

The pitch deviation is defined for bevel gears in standard ISO 17485: 2006. The pitch deviation is defined in the standard ISO 1328-1:2018-03 for cylindrical gears. When reference is made in the present text to pitch deviations, the definitions in the aforementioned standards are used in particular.

In order to comply with predetermined tolerances for bevel gears with permissible pitch or indexing deviations, it is known to carry out so-called pitch or indexing compensation in order to compensate for the pitch deviations caused by thermal expansion of the gears during production.

In this case, for example, the respective depth position of the toothed cutters relative to the gear to be produced is adapted or adjusted for the respective tooth gaps of the gear. In case the gear wheel has, for example, 20 tooth slots, a separate correction of the respective depth position of the tooth producing cutter for the pitch compensation can be provided for each tooth slot. The pitch compensation in this example therefore comprises twenty correction parameters, more precisely one correction parameter per tooth slot.

Furthermore, the rotational position of the gear wheel relative to the toothed tool can be adapted or adjusted, for example, for each tooth slot. With reference to the preceding example, the pitch compensation can therefore have-again individually for each tooth slot to be produced-20 further correction parameters for the rotational position of the gear wheel relative to the tooth-forming tool. The correction values for the depth position and/or the rotational position deviating from the original setpoint data are therefore used as compensation parameters for the pitch compensation.

Alternatively, a separate parameter set may be predefined for each tooth slot, wherein each parameter set may contain a plurality of parameters. The pitch compensation thus comprises 20 parameter sets for the previous example, more precisely one parameter set per tooth slot.

European patent document EP1981674B1 describes such a tooth pitch compensation for bevel gears produced in the single-indexing method. It is known from european patent document EP1981674B1 to compensate for the pitch offset individually for each tooth of a bevel gear in such a way that an indexing error is determined for each tooth or each tooth slot for a reference workpiece and is corrected on the basis thereof. In contrast to a linear, i.e. average tooth spacing compensation of all teeth, this avoids the need to correct those teeth which have no indexing error or those teeth whose linear compensation would lead to an increased indexing error.

It has been shown that in the case of a series production of bevel gear teeth, despite the predetermined pitch compensation, pitch deviations outside the required tolerance range can still occur. This can result in the machine tool operator manually adjusting the compensation parameters of the predetermined pitch compensation in order to comply with the required tolerances for the indexing errors. In this case, long downtimes of the gear cutting machine may result and the proportion of defective parts may also increase.

Disclosure of Invention

Against this background, the object of the invention is to provide a method which enables reliable pitch or indexing compensation in mass production. The aforementioned technical problem is solved by the features of claim 1. Further embodiments of the invention emerge from the dependent claims and the following description.

According to a first aspect, the invention relates to a method for producing a gear wheel, comprising the following method steps: the method comprises the steps of toothing a plurality of gears in a single indexing process with a toothing tool, wherein the toothing tool produces a plurality of tooth slots on each of the plurality of gears by means of a cutting process, and wherein a tooth pitch compensation with a compensation parameter is predetermined for the plurality of gears. The method is characterized in that the compensation parameter is predetermined by a machine tool control device according to the wear state of the tooth-making tool.

The invention is based on the recognition that the pitch deviation to be compensated changes as the tool wear of the toothed tool increases.

If, for example, three hundred gears are to be toothed with the toothing tool before the toothing tool is reground or dressed, an unacceptable tooth pitch deviation can occur, for example, from the first or second hundred finished gears. Tests by the applicant have shown that as the tool wear progresses, that is to say as the tool cutting edge becomes "duller", the heat input into the finished gear increases. This results in increased thermal expansion of the gear during machining, and thus also in a change in the pitch offset to be compensated.

If the tooth-producing tool is in a completely new or reconditioned state, the machine tool control therefore selects different compensation parameters than if the cutting edge of the tooth-producing tool had already been used. The toothing tool can still be regarded as "completely new", for example, for a predetermined number of machined gears, so that a compensation parameter for a completely new state can be used, and if this number is exceeded, further compensation parameters can be used.

Since the tool wear is now taken into account in the determination of the compensation parameters according to the invention, the pitch error can be reliably compensated for in mass production. Manual intervention by the machine tool operator is no longer necessary or can be avoided.

In particular, provision may be made for the compensation parameters to be automatically predetermined by the machine tool control as a function of the wear state of the toothed tool. If the wear state of the tool, which is monitored by the machine tool control, changes, for example, in such a way that a tooth pitch deviation is expected to be outside a predetermined tolerance range for the next gear to be produced, the compensation parameters can be automatically adjusted by the machine tool control in order to avoid scrap parts.

In particular, it can be provided that the compensation parameter is adjusted at least once, in particular at least twice, more particularly at least three times, for a predetermined batch of the plurality of gears, in particular at most once for each gear of the predetermined batch of the plurality of gears.

Provision may be made, for example, for a plurality of gears to be produced in batches of up to 500, in particular up to 400, more particularly up to 300. In particular, it can be provided that a predetermined batch is completely machined with the individual tooth-forming tools before the tooth-forming tools are dressed and sharpened. The series thus currently corresponds in particular to a predetermined number of pieces of the plurality of gears, which should be toothed with the toothing tool without trimming the tool.

When reference is made to the compensation parameters, this is in particular a correction for the feed depth or depth position of the toothing tool relative to the gear wheel and/or a correction for the relative rotational position of the gear wheel relative to the toothing tool. Here, a correction value for the feed depth or depth position and/or a correction value for the relative rotational position of the gear wheel is specified for each tooth of the gear wheel. The compensation parameters may comprise individual correction values or parameters or sets of parameters for each tooth slot or tooth. In particular, a separate parameter set can be assigned to each tooth slot, which may contain a plurality of correction values or parameters.

The correction value may be determined by linear, average correction or individually for each tooth. For a gear wheel with 10 teeth, the compensation parameters thus comprise, for example, 20 correction values, for which the correction value for the feed depth or depth position of the toothing tool relative to the gear wheel and the correction value for the relative rotational position of the gear wheel relative to the toothing tool are specified for each tooth.

The compensation parameters for each tooth or for each tooth gap may alternatively have a parameter set, wherein each parameter set may contain a plurality of correction values or parameters. In this case, for example, for each tooth, a suitable adjustment of one, two or more axes of a CNC-controlled machine or gear processing machine for producing the gear can be provided.

When a changed compensation parameter or a second compensation parameter is currently referred to, then, for example, an adjustment of an existing compensation parameter can be involved. If the first compensation parameter for the third tooth gap specifies, for example, a 10 μm correction of the depth position, this correction of the depth position can be increased by, for example, 5% in order to take account of increased tool wear. All other corrections can likewise be increased by 5% in order to take account of increased tool wear.

It can be provided that the second compensation parameter is automatically calculated from the first compensation parameter by the machine tool control in such a way that a conversion equation is stored in the machine tool control in order to convert the first compensation parameter into the second compensation parameter.

It goes without saying that for a particular tooth or teeth of the gear, one of the correction values may be zero or both correction values may be zero, so that no compensation is required for one or more teeth or only one correction value is predetermined to be unequal to zero.

The correction value is a deviation of the machining or process data, which is generated during the design of the gear wheel on the basis of the theoretical nominal geometry of the toothed segment. In the theoretical machining design, therefore, the same feed depth or depth position of the tool relative to the gear is determined for each tooth gap, since thermal effects are not taken into account here. The same increment of the workpiece spindle rotation, which is carried out after the tooth gap has been produced, is also determined for each tooth gap, which corresponds to a rotation of the workpiece about its own axis by the amount corresponding to the nominal tooth pitch. The correction values adapt these machining data to each tooth or to each tooth slot in order to take account of the heat input by the tooth-forming tool.

When it is currently said that a tooth-making tool is dressed or sharpened, this may mean that the cutting elements of the tooth-making tool are replaced and/or sharpened and, if necessary, recoated. For example, it can be provided that the tooth-making tool has a plurality of exchangeable bar knives, the cutting edges and cutting surfaces of which are worn by chipping or wear during cutting. These bar knives can be sharpened in a grinding machine to produce redefined cutting edges and cutting faces on the bar knives. For example, provision can be made for the cutting edges to be provided with a defined cutting edge rounding in order to increase the tool life. It can further be provided to provide or repair a CVD or PVD coating of the rod-shaped tool in order to increase the tool life.

The toothed tool can be a rod-shaped cutting head, wherein the rod-shaped cutting head can have a base body with a cutting receptacle (Messerschacht), and wherein the rod-shaped cutting head is detachably held in the cutting receptacle.

In order to take account of tool wear during the production of larger pieces, provision may be made for a first compensation parameter for the pitch compensation to be predetermined for a first wear state of the toothed tool and for a second compensation parameter for the pitch compensation to be predetermined for a second wear state of the toothed tool, the toothed tool having a smaller tool wear in the first wear state than in the second wear state and the first compensation parameter differing from the second compensation parameter. The compensation parameters can thus be adapted to the tool wear by means of the machine tool control. It is thus also possible to ensure that the predetermined pitch tolerance is reliably maintained with increasing tool wear, without requiring user intervention.

It can therefore be provided that the pitch compensation of a first part of the plurality of gears is carried out with a first compensation parameter and the pitch compensation of a second part of the plurality of gears is carried out with a second compensation parameter.

According to a further embodiment of the method, it can be provided that a third, fourth or nth compensation parameter for the tooth space compensation is predefined for a third, fourth or nth wear state of the toothed tool, wherein "n" corresponds at most to a predefined number of pieces or a batch of the plurality of gears.

It can thus be provided that the pitch compensation of the third part of the plurality of gears is carried out with a third compensation parameter, the pitch compensation of the fourth part of the plurality of gears is carried out with a fourth compensation parameter and the pitch compensation of the nth part of the plurality of gears is carried out with an nth compensation parameter. Suitable compensation parameters are therefore predetermined for each gear for the case where "n" corresponds to the number of pieces or the batch of the plurality of gears.

The gear to be manufactured may be a bevel gear. In particular, it can be provided that each of the plurality of gears is a bevel gear, in particular a crown gear.

Tool wear can be measured or estimated by means of a test sequence.

When the consideration of tool wear is currently referred to, then the tool wear is not determined or measured directly, in particular, but is preferably taken into account indirectly by monitoring measured values or process variables that influence or are influenced by tool wear.

The number of gears cut with the toothed cutter affects, for example, the wear of the cutter. It can therefore be assumed that the tooth-making tools used to cut 10 gears have less wear than the same tooth-making tools that have already cut 100 such gears. The wear state can thus be measured or determined, for example, in units of "number of gears cut". Tool wear can also be measured in units of "number of tooth slots cut", "volume cut" or "mileage cut".

Since the wear of the toothing tool affects, for example, the current consumption and/or the power consumption of the tool spindle drive, the chip forming energy and the retrofitting energy required for chip removal increase as the wear of the toothing tool increases. The increased wear of the toothing tool therefore leads to a measurable increase in the current consumption and/or power consumption of the tool spindle drive, so that the wear of the toothing tool can be measured in units of "change in the current consumption or change in the power consumption of the tool spindle drive".

It can therefore be provided that the number of gears which are toothed with the toothing tool is determined, wherein the number of gears which are toothed with the toothing tool represents the wear state of the toothing tool. In other words, the wear state of the tooth making tool is determined or measured by the unit "number of gears the tooth making tool makes teeth".

If, for example, it is known that toothed cutters, after more than one third of the expected life and again after more than two thirds of the expected life, usually produce gears whose pitch deviation is outside predetermined tolerances, the compensation parameters can be adjusted accordingly. If, for example, 300 gears are assigned to the toothing tool, the compensation parameter is automatically set once by the machine tool control after the first hundred manufactured gears and automatically set again once again by the machine tool control after the second hundred manufactured gears, for example. The number of gears produced with the toothing tool thus allows an indirect deduction or estimation of the wear state of the toothing tool.

Alternatively or additionally, it can be provided that the current consumption and/or the power consumption of the tool spindle drive for rotationally driving the toothing tool is measured, a change in the current consumption and/or the power consumption representing the wear state of the toothing tool. In other words, the wear state of the tooth-making tool is determined or measured in units of "change in current consumption and/or power consumption of the tool spindle drive".

As already mentioned before, the current or power consumption of the tool spindle drive for rotationally driving the toothing tool allows the wear state of the toothing tool to be inferred in that the current or power consumption of the tool spindle drive rises with increasing tool wear. Because the more worn or "dull" the tooth-making tool, the more energy the tool spindle drive must use to produce the teeth of the gear in order to remove the chip from the tooth-making tool.

The current consumption and/or the power consumption can thus be measured in order to detect different levels of wear state or tool wear, wherein an own data set of compensation parameters can be assigned to each wear level.

For example, it can be provided that, for producing a tooth gap, the current and/or power consumption curve for the new state of the tooth producing tool is known or measured in the new state of the tooth producing tool. The work done to produce the tooth slot can thus be determined, for example, as an integral of the power curve over the duration of the machining. If the work required to manufacture the tooth slot rises, for example, by more than 10% or more than 20%, the compensation parameters are adjusted. This can also be done for current consumption.

Alternatively or additionally, it can be provided that the compensation parameter is set by the machine tool control device as soon as the average or averaged current and/or power consumption of the tool spindle drive exceeds a predetermined setpoint value of the average current and/or power consumption by more than 10%, in particular by more than 20%, during the production of the gear. If an average power consumption of 30kW is predefined as a setpoint value during the production of the bevel gears, the compensation parameters are set by the machine tool control as soon as the measured average power consumption exceeds 33kW (10%) or 36kW (20%).

Alternatively or additionally, it can be provided that the wear state of the tooth-forming tool is deduced by means of at least one of the operating parameters or characteristic variables listed below: an excitation of oscillations or noise caused by the cutting contact of the tooth-making tool, the temperature of the gear to be toothed, the discoloration of the falling chips, the shape of the falling chips.

The operating parameters or characteristic variables can thus be measured in order to estimate different levels of wear state or tool wear, wherein an individual compensation parameter data set can be assigned to each wear level or can be calculated in the machine tool control for each wear level.

The oscillation or noise excitation caused by the cutting contact of the toothed cutter can, for example, increase as the cutter wear increases. Such oscillation excitations or noise excitations may be detected, for example, with a structure-borne sound sensor, a microphone, etc.

The temperature of each toothed gear can be measured after or during the cutting process in order to detect the wear state of the toothed cutter.

The shape and colour of the falling chip also allow the cutting process to be inferred, since in particular the colour of the chip may indicate the temperature occurring in the cutting contact during chip removal.

According to a further embodiment of the method, it may alternatively or additionally be provided that a tooth pitch deviation of at least one of the plurality of toothed wheels is determined, the at least one toothed wheel on which the tooth pitch deviation is measured, in particular one of the 5 last manufactured toothed wheels of a part of the plurality of toothed wheels, and the part of the plurality of toothed wheels, in particular, comprises 20 or more than 20 toothed wheels, wherein the tooth pitch deviation represents a wear state of the toothed cutting tool. In other words, the wear state of the tooth-forming tool is determined or measured in units of "variation in pitch offset". Based on this, new compensation parameters can be calculated or existing compensation parameters can be converted by the machine tool control.

According to a further embodiment of the method, it can be provided that the pitch measurement is carried out in a machine tool with which the plurality of toothed wheels is also toothed by means of a toothing tool. The wear state of the toothed tool can therefore be inferred directly in such machine tools, in which cutting of the gear is also carried out. In this way, the wear state of the tooth-forming tool can be detected effectively and the compensation parameters can be adjusted in the machine tool.

The pitch measurement or the measurement of the pitch deviation can be carried out by means of a tactile measurement method. The measuring head can thus touch all right flanks and/or left flanks one after the other in order to determine the pitch offset. Haptic pitch measurements are robust and less prone to errors than optical measurement methods.

Alternatively or additionally, the pitch deviation can be measured optically. The pitch deviation by means of optical measurement lasts only a few seconds.

The pitch measurement can be carried out clamped in such a way that both the tooth production of the gear to be measured with the tooth production tool and the measurement of the gear take place during the clamping of the gear at the workpiece spindle of the machine tool and the gear is not detached from the workpiece spindle after the tooth production and before the measurement. It is possible to smoothly detect the pitch deviation.

It can be provided that the measurement of the pitch deviation is carried out on every twenty, every ten, every five, every four, every three, every two or every individual gear in order to detect the progression of the pitch deviation with tool wear and to adjust the pitch compensation accordingly, in case the pitch deviation becomes too large and faces production rejects.

Alternatively or additionally, it can be provided that the wear state of the tooth-forming tool is determined by a wear measurement on the cutting edge of the tooth-forming tool. In this case, for example, chipping or wear on the cutting edge and/or the cutting surface of the tooth-making tool can be detected. In particular, wear measurements can be carried out optically on the cutting edges and/or cutting surfaces of the tooth-producing tool.

The predetermined compensation parameter may comprise the following method steps: the stored compensation parameters are read from a data memory of the machine tool control. In the data memory, different data sets of the compensation parameters can be stored for the tooth-forming tools, wherein the wear state of the tooth-forming tool is set for each data set.

The compensation parameters can be determined, for example, by means of measurement and/or simulation.

In order to determine the compensation parameters, it can be provided that interpolation is carried out between the stored compensation parameters stored in the data memory of the machine tool control.

It can be provided that similar compensation strategies are used for similar gear-tooth cutter pairs. If the wear properties of the toothing tool for a gearwheel made of a specific material are known, for example, it is possible to deduce therefrom the wear properties of a similar toothing tool that should likewise be used for cutting gearwheels made of this material.

According to a second aspect of the present invention, there is provided a machine tool control device for manufacturing a gear, characterized in that the machine tool control device is capable of acquiring a wear state of a tooth making tool;

the machine tool control device can predetermine a compensation parameter according to a wear state of the tooth making tool so as to predetermine a pitch compensation using the compensation parameter for the plurality of gears.

In some embodiments, the machine tool control device can acquire a first wear state of the tooth-forming tool, and can predetermine a first compensation parameter for pitch compensation for the first wear state of the tooth-forming tool.

In some embodiments, the machine tool control device can acquire a second wear state of the tooth-forming tool, and can predetermine a second compensation parameter for pitch compensation for the second wear state of the tooth-forming tool.

In some embodiments, the tooth making tool has less tool wear in the first wear state than in the second wear state. The first compensation parameter is different from the second compensation parameter.

In some embodiments, the machine tool control device can automatically calculate a second compensation parameter from the first compensation parameter, wherein a conversion formula is stored in the machine tool control device in order to convert the first compensation parameter into the second compensation parameter.

According to a third aspect of the invention, it relates to a machine tool for manufacturing gears, comprising:

a teeth forming tool configured to form teeth for a plurality of gears in a single indexing method, wherein the teeth forming tool can form a plurality of tooth grooves in each of the plurality of gears by cutting,

a machine tool control device, in particular according to some embodiments, is configured for predetermining a compensation parameter as a function of a wear state of a tooth-making tool, in order to predetermine a pitch compensation for the plurality of gears using the compensation parameter.

In some embodiments, the machine tool further comprises:

a first sensor device configured to determine the number of gears that have been formed with the teeth forming tool, wherein the number of gears that have been formed with the teeth forming tool represents a wear state of the teeth forming tool; and/or

A second sensor device configured to measure a current consumption and/or a power consumption of a tool spindle drive for rotationally driving the tooth-forming tool, wherein a change in the current consumption and/or the power consumption is indicative of a wear state of the tooth-forming tool; and/or

A third sensor device configured to determine a tooth pitch deviation of at least one of the plurality of gears, wherein the tooth pitch deviation represents a wear state of the tooth making tool; and/or

A fourth sensor device configured to measure wear on the cutting edge of the tooth producing tool to determine a wear state of the tooth producing tool.

In some embodiments, the pitch measurement is performed in a machine tool with which the toothing of the plurality of gears with the toothing tool is also performed.

Drawings

The invention will be explained in more detail below with the aid of the drawings showing embodiments. In the figure:

fig. 1 shows a gear wheel schematically in a transverse section with a measuring device for measuring the tooth pitch;

FIG. 2 schematically shows the measurement of pitch deviation with and without pitch compensation;

FIG. 3A schematically illustrates a crown gear in a perspective view from above;

FIG. 3B schematically illustrates a close-up view of the crown gear of FIG. 3A;

FIG. 4 schematically illustrates a gear cutting machine;

figure 5 schematically shows a tooth making tool and a crown gear;

FIG. 6 schematically illustrates a bar knife and gullet;

FIG. 7A schematically shows a bar knife in a completely new state;

FIG. 7B schematically illustrates the bar knife of FIG. 7A in a worn state;

fig. 8 schematically shows a flow chart of the method according to the invention.

Detailed Description

In fig. 1, a gear 100 is shown, the teeth of which are numbered with the numerals 1-12. The geometry of the gear 100 is detected by means of an optical measuring system 200 and a tactile measuring system 300. In this case, a single offset f of the tooth pitch of the right tooth flank 110 of the gearwheel 100 is shown by way of example_ptThe measurement of (2).

Nominal pitch (or nominal division) P_SOLLIs a theoretically predetermined distance of two adjacent right flanks 110 or two adjacent left flanks 120 in the size of the diameter D. Single deviation of tooth pitch f_ptFor each tooth, the actual measured pitch P_ISTMinus the nominal pitch P_SOLLThe difference of (a) to (b) is obtained.

Single deviation of tooth pitch f_ptIs positive for tooth 6 because of the measured pitch P_ISTGreater than nominal pitch P_SOLL. Single deviation of tooth pitch f_ptIs negative for tooth 8 because of the measured pitch P_ISTLess than nominal pitch P_SOLL. The tooth flanks to be generated are each shown in principle by a dashed line. Of course, this is a strongly schematic illustration in order to clarify the deviations occurring in the micrometer range.

One example of the results of such a pitch measurement for the right tooth face is shown in fig. 2. The accumulated pitch error F on the one hand clarifies the total pitch deviation F_PAnd likewise indicates a single deviation f of the tooth-to-tooth pitch_pt. In the diagram, the pitch is offset by a single factor f for this purpose for the number of the corresponding tooth_ptAnd sequentially adding. The total deviation F for the teeth 7 is therefore represented in the diagram as a single deviation F for all tooth distances up to the teeth 7_ptThe sum of (a) and (b).

After pitch compensation is performed for the gear 100, the hatched bars represent the pitch deviation in fig. 2 by way of example. The pitch offset can therefore be reduced decisively by pitch compensation.

The method according to the invention is described below for the continuous production of teeth for bevel gears by means of the production of a driven or crown gear 400. When referring to the continuous toothing of bevel gears, this is a gear pair consisting of a drive gear (or pinion) and an associated output gear (or crown gear), which is provided for changing the rotational speed and the torque between intersecting or offset axes by rolling of the individual teeth in a mutual toothing.

Fig. 3A shows a crown gear 400 in a perspective view from above. Fig. 3B shows an enlarged partial view of the crown gear 400, wherein the enlarged portion is designated with III-B in fig. 3A.

Crown gear 400 has teeth 410, wherein each tooth has a concave tooth surface 411 and a convex tooth surface 412 and a tooth space 413 is formed between teeth 410. In the enlarged illustration according to fig. 3B, the actual pitch P is shown for two adjacent convex tooth flanks 412 by way of example_IST。

Fig. 4 shows a gear processing machine 500 for producing bevel gears, for example a crown gear 400 according to fig. 3A. The gear cutting machine 500 has a tool spindle 510 for receiving a bar-shaped tool bit 520. The bar cutter 520 is a tooth-forming tool 520 and is provided for the single-indexing production of the teeth 410 of the respective crown gear 400.

The gear cutting machine 500 has a machine control device 540. The tool spindle drive 550 is used to rotationally drive the toothed tool 520 about its axis.

Crown gear 400 to be machined is held at a workpiece spindle 530 of gear machine 500.

The relative or feed motion of the tool tip 520 with respect to the crown gear 400 is facilitated by three linear axes X, Y and Z, a pivot axis C, and a workpiece rotation axis B. The pivot axis C substantially causes rotation or pivoting of the workpiece spindle 530 about the Z axis. The B axis causes the rotation of crown gear 400 about its own axis L. Tool spindle drive 550, for generating tool rotation or cutting speed, induces rotation about the X axis, where such rotation is labeled a.

Fig. 5 schematically shows a crown gear 400 together with a cutter head 520. The cutter head 520 has a plurality of bar knives 521 arranged to produce concave and convex tooth surfaces 411, 412.

According to the invention, a method for producing a gear 400 is described, comprising the following method steps: the plurality of toothed wheels 400 are toothed in a single-indexing method with a toothing tool 520, wherein the toothing tool 520 produces a plurality of tooth gaps 413 on each toothed wheel 400 of the plurality of toothed wheels 400 by means of a cutting process, and wherein a tooth pitch compensation is predefined for the plurality of toothed wheels 400 with a compensation parameter. The compensation parameters are predetermined by a machine tool control 540 of the machine tool or gear machine 500 depending on the wear state of the toothed tool 520.

For example, the theoretical depth position of the tool 520 in the X direction is corrected by a value Kx for each tooth 410 or for each tooth gap 413 and the theoretical rotational position of the crown gear 400 is corrected by a value Kb, as is schematically illustrated in fig. 6. Here, the dotted line in fig. 6 shows the uncompensated position of the slot, and the solid line shows the compensated position of the slot.

The machine tool control 540 takes into account the wear state of the toothed cutting tool 520.

Provision can be made for a first compensation parameter of the tooth spacing compensation to be predetermined for a first wear state of the toothed tool 520, for a second compensation parameter of the tooth spacing compensation to be predetermined for a second wear state of the toothed tool 520, for the toothed tool 520 to have a smaller tool wear in the first wear state than in the second wear state and for the first compensation parameter to be different from the second compensation parameter.

Fig. 7A shows a bar knife 521 of the tooth making tool 520 in a completely new state. The new state according to fig. 7A corresponds to the first wear state described above. Fig. 7B shows a bar cutter 521 of the tooth making tool 520 in a partially worn state after some of the crown gears 400 are manufactured. The partially worn state according to fig. 7B corresponds to the aforementioned second worn state.

In fig. 7B, a recess 525 is formed, as an example, in the region of the head cutting edge 522, the main cutting edge 523 and the cutting surface 524 of the bar-shaped knife. Due to these recesses 525, the friction and the reshaping work during cutting are increased.

If the bar cutters 521 of the toothed cutter 520 are in a state of partial wear, the heat input during the production of the crown gear 400 is therefore increased compared to the production with the toothed cutter 520 in the completely new state. The expansion rate of the material of the crown gear 400 increases correspondingly during the production, so that the pitch compensation with the first compensation parameter (which enables a predetermined tolerance to be reliably adhered to for the completely new state of the toothed cutter 520) is no longer effective for the state of wear of the toothed cutter 520. For this reason, for the worn state of the toothed tool 520, a different tooth pitch compensation is predefined by the machine control 540 with a second compensation parameter compared to the completely new state.

In accordance with the present embodiment of the invention, therefore, it is provided that the tooth spacing compensation for a first part of the plurality of toothed wheels 400 is carried out using a first compensation parameter and the tooth spacing compensation for a second part of the plurality of toothed wheels 400 is carried out using a second compensation parameter.

Here, the plurality of gears 400 may have a predetermined number of pieces provided for manufacturing with the tooth making tool 520 before dressing the tooth making tool. For example, it can be provided that before the finishing of the toothing tool 520, a number of 300 gears 400 are produced with the toothing tool 520. Here, the first partial gear for which pitch compensation is performed using the first compensation parameter may be, for example, 200 pieces, and thus the second partial gear for which pitch compensation is performed using the second compensation parameter may be 100 pieces.

To select the appropriate compensation parameters, the wear state of the tooth producing cutter 520 is determined. In particular, influencing variables or parameters are taken into account here which allow the wear state of the tooth-forming tool to be indirectly inferred. In some embodiments, this can be achieved, for example, by means of suitable sensor devices or detection devices.

According to a first variant of the method according to the invention, it is provided that the wear state of the toothed tool 520 is inferred from the number of toothed wheels 400 which are toothed with the toothed tool 520. If, for example, it is known for the toothed wheel 400 that the pitch compensation can no longer achieve the required tolerances from the number of approximately 200 produced toothed wheels 400, the machine tool control 540 can automatically use a second compensation parameter, which takes into account the expected tool wear, from the second or one hundred eighty produced components instead of the first compensation parameter. Compensation parameters for different wear states of the toothed tool 520 can therefore be stored in a database of the machine tool control.

The procedure according to the first method variant of fig. 8 is therefore as follows: in step a, the gear 400 is manufactured with a first compensation parameter. In step b it is checked whether the number of produced gears is less than or equal to, for example, 180. If the check in step b indicates that the number of gears produced is less than or equal to 180, the gear 400 is again produced with the first compensation parameter. If the check in step b indicates that the number of gears produced is greater than 180, the next gear 400 and further subsequent gears 400 are produced according to step c using the second compensation parameter.

According to a second variant of the method according to the invention, it is provided that the wear state of the toothing tool 520 is inferred from the current and/or power consumption of the tool spindle drive 550 of the tool spindle 510 for rotationally driving the toothing tool 520. In some embodiments, this can be achieved, for example, by means of suitable sensor devices or detection devices. The current consumption and/or the power consumption of tool spindle drive 550 of tool spindle 510 for rotationally driving toothed tool 520 is continuously detected during the production of gear 400 and evaluated by machine tool control 540. If it is ascertained in the machine tool control 540 that the average power consumption during the cutting of the gear 400 has increased by more than 20% compared to the previously produced gear or the predetermined setpoint value, the compensation parameters can be set for the next component by the machine tool control 540. Since increased power consumption implies dulling or wear of the tooth cutters 520.

The flow of the second method variant is thus as follows, for example, according to fig. 8: in step a, the gear 400 is manufactured with the first compensation parameter. In step b, it is then checked whether the average current consumption and/or the power consumption of tool spindle drive 550 of tool spindle 510 has increased by more than 20% compared to a predetermined target value. If the average current consumption and/or power consumption of the tool spindle drive 550 of the tool spindle 510 does not rise above a predetermined nominal value or rises below 20%, the next gear 400 is manufactured with the first compensation parameter. In case the average current consumption and/or power consumption of the tool spindle drive 550 of the tool spindle 510 rises above 20% compared to the predetermined nominal value, the next gear 400 and further subsequent gears 400 are manufactured according to step c with the second compensation parameter.

According to a third variant of the method according to the invention, it is provided that the wear state of the toothing tool 520 is inferred by means of a measurement of a tooth pitch deviation of at least one of the plurality of toothed wheels 400. In some embodiments, this can be achieved, for example, by means of suitable sensor devices or detection devices. The at least one gear 400 on which the pitch deviation is measured is in particular one of the five last manufactured gears of a part of the plurality of gears 400, and this part of the plurality of gears 400 comprises in particular 20 or more than 20 gears. It is therefore possible to check at predetermined intervals: the currently used compensation parameters are effective to compensate to what extent the pitch deviation is, or whether the tool wear has already progressed such that the machine tool control 540 has to adjust the compensation parameters to reliably comply with the predetermined tolerances.

The pitch measurement is performed in a machine tool or gear machine 500. The pitch measurement is therefore carried out in the jig in such a way that both the tooth making of the gear of the plurality of gears 400 with the tooth making tool 520 and the measurement of the gear 400 are carried out during the clamping of the gear 400 on the workpiece spindle 530 of the machine tool 500, and the gear 400 is not disengaged from the workpiece spindle 530 after the tooth making and before the measurement. The pitch deviation is measured tactilely at the present time.

The flow of the third method variant is thus as follows according to fig. 8, for example: in step a, the gear 400 is manufactured with the first compensation parameter. In step b, it is then checked whether the pitch offset of the gear 400 to be measured lies within a predetermined tolerance. If the pitch deviation is within tolerance, a further gear 400 is manufactured with the first compensation parameter until another gear is remeasured in step b. If the pitch deviation is outside the tolerance, the next further gear 400 is manufactured according to step c using the second compensation parameter.

According to a fourth variant of the method according to the invention, the wear state of the tooth producing tool 520 is determined by wear measurements at the cutting edges 521, 522, 523 of the tooth producing tool 520. The wear measurement may be performed optically. In some embodiments, this can be achieved, for example, by means of suitable sensor devices or detection devices.

The flow of the fourth method variant is thus as follows according to fig. 8, for example: in step a, the gear 400 is manufactured with the first compensation parameter. In step b, it is then checked whether the tool wear of the toothed tool 520 lies within a predetermined tolerance. If the tool wear is within tolerance, a further gear 400 is manufactured with the first compensation parameter until the tool wear is re-measured in step b. If the tool wear is outside the tolerance, the next further gear 400 is manufactured according to step c with the second compensation parameter.

The predetermining of the compensation parameters currently comprises reading the stored compensation parameters from a data memory of the machine tool control.

The aforementioned method variants can be combined with one another.

From step c, the tool wear can be monitored continuously, similarly to fig. 8, in order to use the third or fourth compensation parameter, if necessary.