DE102010055820A1 - Method for measuring of oversize of operating gear with rotational axis, involves providing gear tooth system with multiple teeth at outer or inner circumference of gear - Google Patents

Abstract

The method involves providing a gear tooth system (4) with multiple teeth (5) at outer or inner circumference of a gear (2). A position of an upper surface of tooth flank (6) is determined by optical distance measurement through a distance sensor. The measurement of oversize is carried out by the distance sensor such that the gear is twisted around a rotational axis (3). The distance sensor is displaced in the direction of the rotational axis.

Description

The invention relates to a method for measuring the allowance of a hartfeinzubearbeitenden gear with a rotation axis, wherein the gear on its outer and / or inner periphery has a toothing with a number of teeth, the teeth have on their tooth flanks a comparison with the finished geometry existing oversize wherein the position of the surface of the tooth flank provided with the measure is determined by optical distance measurement by a distance sensor by a light beam from the distance sensor is directed to the surface, and wherein the light beam is directed onto the surface so that it is perpendicular to the axis of rotation or parallel to this direction.

A method of this kind is known from US 4 547 674 known. There, the tooth flanks of a gear are measured by means of a laser distance sensor. It is provided that the measurement and oversize determination is carried out discontinuously in a tooth space of the toothed wheel, ie, gap by gap is measured successively.

Especially in the production of gears, the final hard finishing process is of major importance. In this example, the tooth flanks are subjected to a grinding operation, with which they are brought to the exact contour. An efficient procedure in the production of the toothing is generating grinding with a grinding worm or profile grinding with a profile grinding wheel.

Gears of gears which are to be subjected to such hard finishing after hardening in order to obtain the required precise geometry generally have a hardening delay after hardening. This results in a corresponding size of the hardening distortion especially during hard fine machining by the discontinuous profile grinding after centering the profile grinding wheel in the tooth gap to a plurality of grinding strokes without contact between the tool and the workpiece. If you want to avoid these empty strokes, the measurement situation in each tooth gap must be known.

Although the generic optical measuring of the tooth flanks already allows a more efficient and faster measurement than, for example, the measurement of the oversize distribution by means of mechanical measuring probes.

The disadvantage, however, that the measurement times are still relatively high. Accordingly, there are non-productive times which reduce the economy of the hard finishing process, in particular the grinding process.

The invention is therefore based on the object to propose a generic method for measuring the allowance of a gear, with which the Aufmaßsituation can be determined even faster and yet sufficiently accurate. Another aspect that is to be considered by the invention is the achievement of a measurement result that is protected against possible measurement errors.

The solution of this problem by the invention is characterized in that the measurement of the allowance by means of the distance sensor is at least temporarily so that simultaneously the gear is rotated about the axis of rotation and the distance sensor is translationally displaced in the direction of the axis of rotation.

The translational displacement is preferably carried out at a constant speed. Accordingly, the distance sensor at least partially overscrew the teeth to be measured helically or helically.

The gearwheel is continuously rotated about the axis of rotation during the entire measurement in accordance with a preferred embodiment of the method.

The distance sensor can be moved continuously translationally from one axial end of the toothing to the other axial end of the toothing.

But it is also possible that at least one axial position between the two axial ends of the toothing, the translational displacement of the distance sensor is interrupted and a measurement of the oversize takes place by the gear continuously rotates and the distance sensor remains at an axial position. The measurement of the allowance can be made in this case, until the gear has rotated 360 °. Furthermore, according to a development in this case, it is provided that the measurement of the allowance with a remaining distance sensor remains at a number of equidistantly spaced-apart axial positions.

The distance sensor is preferably arranged on an axle slide of a gear hard finishing machine, wherein the axis of the axis slide is used to move the distance sensor in a defined manner. In this case, advantageously can be dispensed with a separate drive axle for the distance sensor. It is thus preferably provided that no separate feed device for the distance sensor is used, but that the measuring head on a carriage or on a stand of the Machine tool is placed in order to use the machine axes for positioning.

The teeth of the gear are preferably arranged on an outer or inner cylindrical surface.

The determination of a stable measurement result of the measurement measurement is fostered further development in that the measurement of the position of the surface initially takes place so that the light beam is oriented so that it lies in a direction which is perpendicular to the axis of rotation, wherein a value determined by the distance sensor for the position of the surface of the tooth flank is subjected to a plausibility check before the utilization, if the value lies in an expected range of values, and wherein in the case that implausible measured values are present or are to be expected, the optical distance measurement takes place in a position in which the light beam is displaced by a defined distance parallel to the direction perpendicular to the axis of rotation (ie parallel to a central plane comprising the axis of rotation).

The plausibility check is carried out in particular such that a measured value is subjected to a comparison with a stored value range.

The last-mentioned embodiment of the method is advantageous if, under certain circumstances, the measurement sharpness is impaired by the fact that the measuring beam impinges on the surface of the tooth flank at an acute angle. The measured value can be discarded within the scope of the aforementioned plausibility check if it is not within the value range. It can also be provided that a measured value not lying within a predetermined value range is replaced by a measured value resulting from interpolation or extrapolation of adjacent measured values.

In this case, according to the invention, the oversize data obtained in the helical-type method of the distance sensor relative to the toothing is converted such that the measurement situation results in each tooth space.

Since, due to the helical measurement, the complete measurement data are not naturally present in a multitude of planes perpendicular to the axis of rotation, the invention makes use of the consideration that, due to the prefabrication processes (eg hobbing), there is a high probability that the oversize distribution in a tooth gap over the width of the teeth within certain tolerance limits continuously.

Thus, if a helical measurement is made, the oversize distribution is virtually absorbed once over the circumference and once in the direction of the width of the toothing, thereby closing the distribution of allowances in all tooth gaps and over the entire width of the toothing.

In this case, the procedure is preferably concretely such that the theoretical position of the tooth flanks is calculated along the helix and traversed with the sensor. The sensor records the actual position data of the tooth flanks during the helical relative movement. Then the measured values of the tooth flanks are compared with the theoretical values.

Surprisingly, it has been found that despite the omission of a large number of measured values, this measurement of the excess provides a very practicable image and offers the great advantage that the measurement of the excess can take place in a very short time.

The light beam is preferably a laser beam. The optical distance measurement is preferably carried out according to the triangulation method.

In particular, the said method is carried out before a gear grinding operation is carried out, in particular before a discontinuous profile grinding operation is carried out.

In optical systems in which the reflected light is evaluated, there is the problem that the quality of the measurement signal depends on the angle of the reflected surface at which the measurement signal impinges on the surface to be measured. With gears, the angle of incidence towards the foot becomes sharper. From a certain critical angle, a sufficiently accurate measurement is no longer possible. To solve this problem, the above-explained plausibility check is proposed.

The result is information about the measurement situation in each tooth gap. Unplausible values are discarded or replaced by interpolated or extrapolated values.

Another preferred embodiment of the invention provides that the optical measuring system (distance sensor) is tangentially displaced in a position to the center axis of the gear. Depending on the tangential displacement (positive or negative), one flank of the gear can be measured with improved measuring angles.

However, it can also come here for measuring in the limit range and thus to non-usable measurements, so that then explained above Method of plausibility check can be used.

An essential aspect of the present invention is thus that the measurement of the dimensions takes place with the gear rotating continuously.

For measuring a helical gearing, it is particularly advantageous to arrange the distance sensor (measuring head) such that the plane formed by primary and reflected beam corresponds to the helix angle of the gearing.

The simplest case of measuring the girth of a gearing is done in an efficient manner by a continuous rotation of the gear and measurement of the allowance in mutually parallel planes which are parallel to the end face. The planes to be measured are measured successively after a corresponding axial movement of the distance sensor. From the measured planes, the geometry of the oversize of the entire toothing can then be calculated and displayed. It is advantageous if non-interest areas such. B. the toothed head or foot can be eliminated in a suitable manner from the measured values.

An alternative to this is that during the axial displacement, d. H. during the displacement of the distance sensor to the next level, the continuous rotation of the gear is not stopped. The measurement in the new plane takes place after the gearwheel has rotated by a defined angle of rotation. This is then taken into account in the calculation of the geometry of the Aufmaßdaten the teeth accordingly.

However, preference is given to the solution according to which no planes are measured (with axially persistent distance sensor) more, but from the continuous rotation and a simultaneous continuous axial movement a helical measurement is made. Thereafter, again, a calculation of the geometry of the Aufmaßverteilung the teeth.

In the drawing, an embodiment of the invention is shown. Show it:

1 1 is a schematic plan view of a gear to be measured with regard to the oversize and a distance sensor for measuring the oversize;

2 in an enlarged view, two adjacent teeth of the gear and located on the tooth flanks allowance,

3 in the illustration 1 an alternative embodiment and

4 schematically in perspective view of the gear to be measured, wherein the path is outlined, the distance sensor travels relative to the gear.

In the 1 to 3 First, the present principle for measuring the allowance in a gear is explained.

In 1 is schematically a gear 2 sketched on a (not shown) workpiece spindle is taken, whose axis is perpendicular to the plane of the drawing. This axis is as a rotation axis 3 marked. On the outer circumference of the gear is an external toothing 4 arranged. Accordingly, the gear has 2 a number of teeth 5 , the respective tooth flanks 6 exhibit. In the gap, the two adjacent tooth flanks 6 form, immersed in the profile grinding in a known manner a correspondingly profiled grinding wheel. As with the detailed representation in 2 can be seen, have the tooth flanks 6 a grinding allowance 1 on, after curing the gear 2 must be ground to the finished geometry 7 the tooth flank 6 to obtain.

In the figures, the situation is simplified in the measurement of a spur gear spur shown. The same applies to helical or internally toothed gears.

The knowledge of the measurement situation, ie the size of the existing allowance on each tooth flank 6 above the tooth height, is essential to the gear 2 optimally centered relative to the grinding wheel. Furthermore, only by the optimal grinding cycle can be defined, ie a grinding that manages with minimal idle strokes without chip removal.

Accordingly, in the present case in the manner described below, the allowance 1 on the tooth flanks 6 determined before grinding:
The oversize measurement is carried out by means of a distance sensor 9 , a ray of light 10 sending out. From the analysis of the reflected light, the distance between the distance sensor 9 and the point of the surface 8th the tooth flank 6 be determined, which is currently measured (s. 2 ). The light beam 10 is oriented so that it lies in a direction N, which is perpendicular to the axis of rotation 3 stands. Ie. the beam of light 10 lies in the middle plane of the gear 2 that is also the axis of rotation 3 includes.

Will the gear 2 around the axis of rotation 3 rotated by a rotation angle Φ, therefore, the tooth flank 6 Traversed over the tooth height and the respective allowance are measured.

Meets the measuring beam 10 perpendicular to a surface, the measurement is optimal. However, it can be problematic if the measuring beam 10 at too small an angle α on the surface 8th occurs (s. 2 ). In this case, the measurement uncertainty is increased until finally no measurement is possible (angle α to zero degrees).

In order to eliminate this problem, the following can be provided: On the one hand, a plausibility check is provided, which in 1 is indicated. For this is a storage means 12 present in which for a concrete gear 2 (for each rotation angle of a target value W _Set is stored together with the tolerance band. Thus is the target value W _set on in which value range Aufmaßwert may be measured for an angle Φ. The target value W _target is a comparator 13 fed. This receives next to the setpoint W _setpoint also the distance sensor 9 currently measured value W _is . In the comparator 13 a comparison is made as to whether the current measured value W _ist lies within the value range which is predetermined by the setpoint value together with the tolerance band W _setpoint . If this is the case, the measured value is output as a checked value W _G and passed on or output as the oversize value for the relevant edge position.

If the measured value W _is not within the range of the tolerance band according to the value W _setpoint , it can be assumed that a faulty measurement has occurred due to the above-described measurement uncertainty. Accordingly, the measured value W _is not useful.

In this case, two options are available: First, the measured value can be rejected as improperly and a corresponding gap left over the tooth height in the course of the oversize. On the other hand, it is also possible to reject the measured value and replace it by a value which results from the interpolation between adjacent values or which results from the extrapolation from measured values that have already been measured and found to be good.

There is indeed still another possibility, in the case mentioned - ie if the measured spot too small angle α to the light beam 10 - to arrive at useful readings.

This is in 3 outlined. After that, the distance sensor 9 on a linear guide 11 be moved in a direction of displacement T, which is perpendicular to the direction N; accordingly, the distance sensor becomes 9 so shifted that the light beam 10 in a direction P parallel to the direction N radiates. The displacement of the distance sensor 9 from the middle plane of the gear 2 is denoted by a. As based on 3 can be seen, so that is the angle α ', below which the light beam 10 on the surface 8th the tooth flank 6 impinges, significantly larger, so that a useful measurement can be made.

In view of the fact that the above-mentioned problems of measurement uncertainty generally occur at a certain flank angle, the measurement can be carried out in the shifted position even without carrying out the above-explained plausibility check above a certain slope of the flank. This can of course be either side of the center plane of the gear 2 done by the dashed in 3 drawn distance sensor 9 is indicated. While the position of the distance sensor drawn with solid lines 9 for the in 3 right tooth flanks 6 is used, the drawn in dashed line position for the measurement of the left tooth flanks in question.

The inventively proposed principle goes out 4 out:
Here, the procedure is first described, as it is typically used for a narrow, spur gear.

Here it is provided that the measurement of the allowance 1 by means of the distance sensor 9 so happens that simultaneously the gear 2 around the axis of rotation 3 rotated and the distance sensor 9 is moved translationally in the direction of the axis of rotation.

Accordingly, the distance sensor describes 9 relative to the gear shown helical or helical path. The measured values are continuously collected. The measuring process starts when the distance sensor 9 at one axial end 14 the gearing 4 located. Due to the translatory feed, the distance sensor moves 9 to the other axial end 15 while at the same time the gear 2 rotates.

The rotational movement is in the embodiment (for a narrow, spur gear) so tuned that the gear just 360 ° about the axis of rotation 3 has turned when the distance sensor 9 the axial end 15 reached.

The measurement of the oversize values thus takes place starting in a first plane E ₁ , which is at the level of the first axial end 14 lies and perpendicular to the axis of rotation 3 stands; the measurement ends in a second plane E ₂ , which is equal to the second axial end 15 lies and also perpendicular to the axis of rotation 3 stands.

In order to achieve improved data acquisition and in particular to optimally measure wider, helical gears, the measurement is preferably carried out over several revolutions. The preferably performed rotation is n times 360 ° (n as an integer) plus the angle that results from the pitch of the helical gear.

The permanently measured extent values, which are ascertained as explained above, can now be converted in knowledge of the rotational movement and the translatory movement movement in such a way that the allowance in the individual tooth gaps results.

A variation of the measuring method provides at least one axial position between the two axial ends 14 . 15 , So in a third, not drawn plane, the translational displacement of the distance sensor 9 to interrupt and here a measurement of the oversize 1 make by the gear 2 continuously turns and the distance sensor 9 remains at said axial (intermediate) position.

Here, the measurement of the oversize 1 done until the gear 2 once rotated around itself, ie 360 °.

This procedure can be repeated for several intermediate levels.

Because of the machine axes both the rotation about the axis of rotation 3 as well as the translational displacement of the distance sensor is known, in turn, the Aufmaßverteilung can be calculated and displayed.

The said intermediate planes can be uniformly spaced between the first and second axial ends 14 . 15 be confiscated.

Said measurement by means of the optically operating distance sensor 9 is known as such from various fields of technology. Details are in the DE 10 2009 036 776 A1 described; reference is made to this.

LIST OF REFERENCE NUMBERS

1

oversize

2

gear

3

axis of rotation

4

gearing

5

tooth

6

tooth flank

7

finished geometry

8th

surface

9

distance sensor

10

beam of light

11

linear guide

12

storage means

13

comparator

14

axial end

15

axial end

N

Direction perpendicular to the axis of rotation

P

Direction parallel to the direction N

T

displacement direction

a

distance

E ₁

level 1

E ₂

Level 2

Φ

angle of rotation

α, α '

angle

W _target

Reference value including tolerance band

W _is

reading

W _G

verified value

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4547674 [0002]
• DE 102009036776 A1 [0064]

Claims (10)

Method for measuring the oversize ( 1 ) of a hard-to-machine gear ( 2 ) with a rotation axis ( 3 ), wherein the gear ( 2 ) on its outer and / or inner circumference a toothing ( 4 ) with a number of teeth ( 5 ), wherein the teeth ( 5 ) on their tooth flanks ( 6 ) one compared to the finished geometry ( 7 ) existing allowance ( 1 ), wherein the position of the surface ( 8th ) with oversize ( 1 ) provided tooth flank ( 6 ) by means of optical distance measurement from a distance sensor ( 9 ) is determined by a light beam ( 10 ) from the distance sensor ( 9 ) on the surface ( 8th ), and wherein the light beam ( 10 ) so on the surface ( 8th ), that it is perpendicular to the axis of rotation ( 3 ) (N) or parallel to this direction is (P), characterized in that the measurement of the oversize ( 1 ) by means of the distance sensor ( 9 ) at least temporarily so that simultaneously the gear ( 2 ) about the axis of rotation ( 3 ) and the distance sensor ( 9 ) in the direction of the axis of rotation ( 3 ) is translated translationally. Method according to claim 1, characterized in that the gear ( 2 ) continuously around the axis of rotation during the entire measurement ( 3 ) is rotated. Method according to claim 2, characterized in that the distance sensor ( 9 ) continuously translationally from an axial end ( 14 ) of the gearing ( 4 ) to the other axial end ( 15 ) of the gearing ( 4 ) is moved. A method according to claim 2, characterized in that at least one axial position between the two axial ends ( 14 . 15 ) of the gearing ( 4 ) the translational displacement of the distance sensor ( 9 ) and a measurement of the oversize ( 1 ) takes place by the gear ( 2 ) continuously rotates and the distance sensor ( 9 ) remains at an axial position. Method according to claim 4, characterized in that the measurement of the oversize ( 1 ) takes place until the gear ( 2 ) has rotated 360 °. Method according to claim 4 or 5, characterized in that the measurement of the oversize ( 1 ) with persisting distance sensor ( 9 ) takes place at a number of equidistantly spaced axial positions. Method according to one of claims 1 to 6, characterized in that the distance sensor ( 9 ) is arranged on an axle slide of a gear hard-finishing machine, wherein the axis of the axle slide is used to move the distance sensor ( 9 ) to proceed in a defined manner. Method according to one of claims 1 to 7, characterized in that the teeth ( 5 ) of the gear ( 2 ) are arranged on a cylindrical surface. Method according to one of claims 1 to 8, characterized in that the measurement of the position of the surface ( 8th ) first takes place so that the light beam ( 10 ) is oriented so that it lies in a direction (N) perpendicular to the axis of rotation ( 3 ), one of the distance sensor ( 9 ) determined value for the position of the surface ( 8th ) of the tooth flank ( 6 ) is subjected to a plausibility check prior to utilization, whether the value lies in an expected range of values, and wherein in the event that non-plausible measured values are present or are to be expected, the optical distance measurement takes place in a position in which the light beam ( 10 ) is displaced by a defined distance (a) parallel to the direction (N) perpendicular to the axis of rotation ( 3 ) stands. Method according to Claim 9, characterized in that the plausibility check is carried out by subjecting a measured value to a comparison with a stored value range.

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