DE102010005935B4 - Method for designing a profile grinding process - Google Patents

Abstract

Method for the design of a profile grinding process, characterized in that - for each profile point s of the unwinding of the active surface (15) of the tool (10) from the removal of the allowance (35) of the workpiece (30) oriented in the normal direction (7), a required, the power requirement related to the tool (10) and / or the workpiece (30) is determined, - that the value determined in this way is compared with a technological limit value, and - the delivery amount and the relative feed rate between the tool (10) and the workpiece (30) are selected depending on the workpiece and / or the tool geometry so that the resulting power requirement is less than or equal to the technological limit value.

Description

The invention relates to a method for designing a profile grinding process.

The design of a grinding process, the selection of a feed rate and a delivery, is generally carried out as a function of the Zeitspanvolumens, the product of the feed rate and the delivery or related to the grinding wheel width Zeitspanvolumens. For example, given a given maximum radial delivery then the choice of feed rate for the entire processing is done so that the technological limit of the Zeitspanvolumens or the related Zeitspanvolumens is not exceeded. Mostly work is done with high feed rates and low delivery amounts.

The DE 36 37 758 A1 discloses a method of deep grinding in which the infeed and feed rate are designed to achieve a constant rate of bulk removal. The calculation of this volume includes the grinding wheel width, the infeed and the feed rate.

From the DE 41 19 871 C1 a method for preventing thermal overloading of gears is known, wherein by means of a two-flank rolling test center distance changes between the tested workpiece and a master gear are determined. From these values determined in the feed direction, a permissible feedforward value for the processing is determined in comparison with the permissible relative time span volume for a given infeed.

The present invention is based on the problem to develop a method for profile grinding with low peak time.

This problem is solved with the features of the main claim. For this purpose, a required power requirement related to the tool and / or the workpiece is determined for each profile point s of the development of the active surface of the tool from the removal of the oversize of the workpiece oriented in the normal direction. The value thus determined is compared with a technological limit value. The delivery amount and the relative feed rate between the tool and the workpiece is chosen as a function of the workpiece and / or the tool geometry, the resulting power requirement is less than or equal to the technological limit.

Further details of the invention will become apparent from the dependent claims and the following description of schematically illustrated embodiments.

1 : Profile grinding;

2 : Movement directions of the workpiece and the tool;

3 : Tooth gap with tool;

4 : Large diameter tool engaged;

5 : Small diameter tool engaged;

6 : Grinding wheel contour;

7 : Referenced normal time chip volume and related time span volume over the execution of the grinding wheel contour in Zahnfuß- and tooth flank processing;

8th : Referenced normal time chip volume and related time span volume over the development of the grinding wheel contour in tooth flank processing;

9 : Limits of the related time span volume and the related standard time chip volume over time;

10 : Selection of the product from the normal distance or the radial infeed and the feed rate.

The 1 schematically shows the profile grinding. In the illustrated method, as a tool ( 10 ) a profile grinding wheel ( 10 ) in engagement with a workpiece ( 30 ), z. B. a gear ( 30 ). Instead of the illustrated spur gear with a straight involute toothing, the workpiece ( 30 ) also have a helical toothing, a worm toothing, etc. It is also conceivable with the method trapezoidal profile gaps such. B. at a rack to edit. When profile grinding, the flanks limiting the profile gaps can be offset from each other either individually and in time or can be processed simultaneously and simultaneously.

Both the workpiece ( 30 ) as well as the tool ( 10 ) are rotationally driven in the illustrated embodiment. The rotation axes ( 11 . 31 ) are not parallel to each other and do not intersect.

In the exemplary embodiment, the tool ( 10 ) continue relative to the workpiece ( 30 ) parallel to the workpiece axis ( 31 ) movable, cf. 2 , The Relative movement is at least approximately parallel to the workpiece axis ( 31 ). This means that the axial feed motion with the workpiece axis ( 31 ) an angle of z. B. may include up to 10 degrees. For example, in the in this 2 illustrated equidirectional machining of the toothing ( 32 ) the axial feed direction ( 21 ) of the tool ( 10 ) directed from top to bottom. It is also conceivable that the workpiece ( 30 ) relative to the tool ( 10 ) to move in a feed direction.

For example, when machining a toothing, the workpiece stands ( 30 ) while the rotating tool ( 10 ) when grinding along a parallel to the workpiece axis ( 31 ) oriented tooth gap ( 37 ) emotional. The feed rate along the tooth gap ( 37 ) corresponds to the speed of the axial tool feed.

When machining an uncorrected helical toothing, the feed rate of the tool relative to the workpiece results, for example, from a superimposition of the axial tool feed with the angular speed of the workpiece rotation during the axial tool stroke.

To the tool ( 10 ) in engagement with the workpiece ( 30 ), the tool ( 10 ) z. B. from in the 2 illustrated starting position in the direction of the workpiece ( 30 ) delivered. The delivery direction ( 22 ) of the tool axis ( 11 ) is radially on the workpiece axis ( 31 ). Also, the workpiece ( 30 ) in the direction of the tool axis ( 11 ) be delivered.

That in the 1 illustrated gear ( 30 ) is pre-toothed, for example by means of a Wälzfräsverfahrens and was then cured. It has at least on the tooth flanks ( 33 . 34 ) an oversize ( 35 ) to the finished size ( 44 ), see. 3 , The finished measure ( 44 ) of the workpiece ( 30 ) describes the geometrical dimensions of the finished and ready-to-use workpiece ( 30 ).

The illustrated gear ( 30 ) has 17 teeth ( 36 ). Every tooth ( 36 ) is of two tooth flanks ( 33 . 34 ) limited. Two tooth flanks ( 33 . 34 ) limit a tooth gap ( 37 ). The single tooth ( 36 ) has a head ( 38 ), the two tooth flanks ( 33 . 34 ) the tooth base ( 43 ).

The profile grinding wheel ( 10 ) is repeatedly dressed during use on the grinding machine. Their outer diameter is reduced, for example, from 500 millimeters to 250 millimeters, cf. the 4 and 5 , The illustrated disc ( 10 ) has a z. B. cylindrical central section ( 12 ), on which edge regions (at both flanks) 13 . 14 ), whose generatrices, for example, in a degree of toothing in the simplest case, the desired profile lines of the toothing ( 32 ) correspond.

Before the rotating tool ( 10 ), the workpiece ( 30 ) so around its workpiece axis ( 31 ) that a tooth gap ( 37 ) to the grinding wheel ( 10 ) shows. The single tooth gap ( 37 ) has the contour ( 45 ) before grinding, cf. 3 , During delivery, the profile grinding wheel ( 10 ) in the example of the two-flank cut both to the tooth gap ( 37 ) adjacent tooth flanks ( 33 . 34 ) at the same time. Upon further delivery, the tool penetrates ( 10 ) in the workpiece ( 30 ) and cuts a portion of the allowance ( 35 ) of both tooth flanks ( 33 . 34 ) with a geometrically indefinite edge, cf. 3 , During this process, the tool ( 10 ) with a set feed rate along the tooth gap ( 37 ) emotional. If necessary, the feet ( 41 ) and / or the head regions ( 42 ) mitgeschliffen. The active area ( 15 ) of the grinding wheel ( 10 ) is the sum of the surface of the cylindrical portion ( 12 ) and the lateral surfaces ( 16 ) of the border areas ( 13 . 14 ) when the tool is rotated ( 10 ) about its axis ( 11 ) Contact with the gear ( 30 ) to have. The processing takes place, for example, with simultaneous cooling by means of a coolant.

During grinding, the grinding wheel contacts ( 10 ) the gear ( 30 ) along a line. In the case of two-flank grinding, this contact line usually connects on each of the two tooth flanks ( 33 . 34 ) the tooth head ( 38 ) with the tooth root ( 39 . 46 ). For example, this contact line can be a profile line of the toothing ( 32 ) be. The gearing ( 32 ) may have a head or foot return, a Höhenballigkeit, etc. Grinding wheel side is the contact line z. B. in degree gears each have a surface line of the edge regions ( 13 . 14 ). These can be frontally by a parallel to the grinding wheel axis ( 11 ) oriented contact line. The latter section of the contact line contacts the tooth base ( 43 ), if this is mitgeschliffen.

In order to determine the amount of infeed and the feed rate, first the geometrical data of the actual and the desired toothing and the geometrical data of the active surface ( 15 ) of the grinding wheel ( 10 ) determines a power requirement. From the comparison of the actual and the nominal profile of the individual tooth flank ( 33 . 34 ), the tooth head ( 38 ) and the tooth base ( 43 ) results for each point of the active area ( 15 ) of the grinding wheel ( 10 ) in the normal direction ( 7 ) oriented removal. The removal per stroke is a partial amount of a fictitious normal distance ( 8th ), see. 3 , He is usually less than or equal to this value. Of the fictitious normal distance ( 8th ) - it corresponds to the normal to the tooth flank ( 33 . 34 ) measured allowance ( 35 ) - is generally not constant over the profile height of the gearing ( 32 ). In the exemplary embodiment, this normal distance ( 8th ) at the transition of the tooth flank ( 33 . 34 ) into the tooth base ( 43 ) z. B. 64% of the notional normal value at the transition of the tooth flank ( 33 . 34 ) to the tooth head ( 38 ). In the presentation of the 3 is the fictitious normal distance ( 8th ) at the tooth base ( 43 ) twice the notional normal distance ( 8th ) at the transition of the tooth flank ( 33 . 34 ) to the tooth head ( 38 ). From these quantities, taking into account the feed rate, a related normal-time chip volume Q'w _n results. For example, this is calculated to Q'w _n (s) = Z _n (S) · v

Q'w_n(s):

bezogenes Normalzeitspanvolumen [mm²/s],

Z_n(s):

Abtrag Z_n(s) in Normalenrichtung [mm],

v:

Vorschubgeschwindigkeit [mm/s]

In this equation is

Q'w _n (s):

referenced standard time chip volume [mm ² / s],

Z _n (s):

Removal Z _n (s) in normal direction [mm],

v:

Feed rate [mm / s]

It is the product of the removal Z _n (s) of the grinding wheel in the respective normal direction ( 7 ) in millimeters at the profile point s and the feed rate v along the tooth gap ( 37 ) in millimeters per second. Q'w _n considers the feed rate v, the profile shape of the tool ( 10 ) and the normal oversizes measured perpendicular to the flank line ( 35 ) of the tooth flanks ( 33 . 34 ).

This value is calculated for each profile point s of the active surfaces ( 15 ) of the grinding wheel ( 10 ). The thus-ascertained related normal-time chip volume is a performance variable of the grinding process. It has the dimension square millimeters per second. For example, it gives the for removal of the oversize ( 35 ) required power.

The 6 shows the over the grinding wheel width b and the grinding wheel diameter d plotted course of the grinding wheel profile. The digits along the profile indicate the unwound distance of the corresponding point from the origin of the settlement, here in the center of the grinding wheel. The gearing profile on which this development is based has 27 teeth and a module of 10 millimeters.

In the 7 is the required chip volume Q'w ( 5 ) and the related normal-time chip volume Q'w _n ( 6 ) on the processing of the profile of 6 applied. In this figure, the values of a toothing are shown, in which the tooth root is mitgeschliffen. The value of the related Zeitspanvolumens Q'w is constant along the settlement, in the exemplary embodiment, it is 16 square millimeters per second. The related normal-time chip volume Q'w _n is, for example, along the end peripheral surface ( 17 ) of the grinding wheel constant. In this area, its value corresponds to the value of the time span volume purchased. In the transition into the lateral surfaces ( 16 ) the referenced normal-time chip volume Q'w _n drops to a minimum. Along the lateral surface ( 16 ) it rises z. B. steadily. The related normal-time chip volume Q'w _n is along the entire lateral surface ( 16 ) lower than the related time-wasting volume Q'w.

The used for the interpretation of the normal-time chip volume z. B. from tests determined limit value Q'w _{n, Gr} ( 4 ) is for the front peripheral surface ( 17 ) constant. Along the lateral surfaces ( 16 ) it drops linearly, for example. In the example shown, the radial feed of the tool ( 10 ) relative to the workpiece ( 30 ) and the feed rate of the tool ( 10 ) relative to the workpiece ( 30 ) according to the limit value in the area of the front peripheral surface ( 17 ).

The 8th shows analogous to 7 the curve for a toothing, in which the tooth root is not mitgeschliffen. The maximum power requirement of the standard time chip volume ( 6 ) Q'w _n is in the area of the grinding wheel ( 10 ), the transition of the tooth flank ( 33 ; 34 ) to the tooth head ( 38 ) processed. The power value chosen for this range must be less than or equal to the limit Q'w _{n, Gr} . The geometry of the grinding wheel ( 10 ) dependent limit value course is in the representation of the 8th identical to that in the 7 illustrated limit value course. How the comparison of 7 and 8th shows, if the Zahnfußbereich is not mitgeschliffen, in a design after the normal time chip volume Q'w _n a higher grinding performance can be used as in a design after the Zeitspanvolumen Q'w. In the embodiment of 8th is this increase z. B. 55% compared to the example of 7 , The grinding wheel can thus remove more without damaging the workpiece ( 30 ), z. B. caused by grinding burn.

Decisive for the design is the maximum value of the related normal-time chip volume Q'w _n (s). This results in the technological limit value Q'w _{n, Gr} (determined as a function of the tool geometry _). 4 ) of the reference normal time chip volume, the adjustment parameters of the grinding process. Due to the large Schleifabtrag results in a lower peak processing time. In this case, different profile shapes and different curvatures of the teeth are taken into account.

After grinding the tooth gap ( 37 ) limiting tooth flanks ( 33 . 34 ) will that Tool ( 10 ) against the delivery direction ( 22 ) from the tooth gap ( 37 ) moved out. The workpiece ( 30 ) is moved around its axis of rotation ( 31 ) rotated by one pitch so that now the next tooth gap ( 37 ) to the grinding wheel ( 10 ) shows. The processing of this tooth gap ( 37 ), as described above. By means of this discontinuous profile grinding method, the toothing ( 32 ) are processed quickly and accurately.

During grinding, the grains of the grinding wheel ( 10 ) and the grinding wheel ( 10 ) settles with sanding dust. For example, after predetermined intervals, due to the increase of the motor current, etc., the grinding wheel ( 10 ) trained. Here, the front peripheral surface ( 17 ) and the lateral surfaces ( 16 ) of the grinding wheel ( 10 ) processed. The diameter of the grinding wheel ( 10 ) is thereby reduced.

A dressing of the grinding wheel ( 10 ) is the more necessary the smaller the grinding wheel ( 10 ). At the same time, the non-productive time required for dressing is reduced. These two opposing effects do not cancel each other out, so that the bottom-to-bottom time of the workpiece increases with the tool life ( 10 ) is increased.

After dressing, based on the new grinding wheel geometry, a new course of the related normal-time chip volumes is determined. Thereafter, starting from the maximum value of the referenced normal-time chip volume, the new feed rate and the new delivery are determined in comparison with a tool geometry and / or workpiece-dependent technological limit value of the normal-time chip removal volume. Here, for example, either the feed rate or the new delivery amount is specified and the other value is designed so that from the set sizes and the geometric data of the grinding wheel ( 10 ) gives a value less than or equal to the permissible standard normal chip removal volume. An adjustment of the feed rate and the delivery amount is conceivable.

In the 9 A qualitative course of the tool geometry-dependent technological limit is shown. In the abscissa the time is plotted, in the ordinate the related time-wast volume and the related normal time span volume. The time axis describes the main time of the grinding process. At predetermined intervals, the grinding wheel ( 10 ) and thereby reduced its diameter. The between dressings ( 51 ) z. B. constant grinding wheel diameter ( 18 ) are shown as horizontal lines.

The limit value of the related time-wasting volume Q'w _Gr determined according to the prior art remains constant throughout the grinding process. The z. B. in tests determined limit value of the related Normalzeitspanvolumens Q'w _{n, Gr} decreases with increasing process time and / or with decreasing grinding wheel diameter. As the diagram further shows, it is possible, for example, to work with a used normal-time chip volume until the time of the second dressing, which is significantly higher than the limit of the relative chip removal volume. The usable loop energy is thus higher than in a design according to the related Zeitspanvolumen.

The 10 represents as a product of the selected delivery and the selected feed rate, the selected time chipping volume or the selected normal time chip volume. Due to the higher limit of the referenced normal time chip volume, a higher Abtragsrate can be selected as in a design according to the related Zeitspanvolumen. For example, in the 10 at the same feed rate a larger delivery amount selected.

In the in the 6 - 10 For the sake of simplicity, the constants and correction factors are not taken into account. The setting of the parameters of the radial delivery and the relative feed rate can be done automatically, for example, after specification of one of these parameters.

Instead of the active wheel width, the volume to be removed or removed can be applied to the active wheel surface ( 15 ). The thus determined related power requirement H'w has the dimension millimeters per second. This value is also determined for each point of the settlement.

The related power requirement H'w is different for profile points which lie on different profile lines, since both the distance of the respectively contacting grinding wheel point from the axis of rotation ( 11 ) of the grinding wheel ( 10 ) to the tooth head ( 38 ) and the fictitious normal distance ( 8th ) to the tooth head ( 38 ) increases.

H'w:

bezogener Leistungsbedarf [mm/s]

k(s):

Korrekturfunktion, dimensionslos

s:

Bogenlänge der Abwicklung [mm]

v:

Vorschubgeschwindigkeit in Lückenrichtung [mm/s]

Z(s):

Abtrag, z. B. pro Hub [mm]

N(D_sls(s)):

Funktionswert in Abhängigkeit der Bogenlänge der Abwicklung s [mm].

The related power requirement H'w is given by H'w = k (s) * v * Z _n (s) / (π * N (D _sls (s))) where the variables mean:

H'W:

related power requirement [mm / s]

k (s):

Correction function, dimensionless

s:

Arc length of the processing [mm]

v:

Feed rate in gap direction [mm / s]

Z (s):

Removal, z. Eg per stroke [mm]

N (D _sls (s)):

Function value depending on the arc length of the settlement s [mm].

The correction function k (s) takes into account, among other things, the influences of the contact line profile, the contour to be ground, the contact line length, the coolant quantity, the coolant discharge, the heat dissipation, the number of grains and the pore volume.

The function value depending on the diameter of the grinding wheel ( 10 ) takes into account, for example, the profile shape of the grinding wheel ( 10 ). So the value z. B. at a decreasing pressure angle on the pitch circle.

The determined power requirement is compared with a limit value. This z. B. in tests determined limit value is independent of the geometry of the tool ( 10 ) and the workpiece ( 30 ). For example, it is dependent on the material combination of the tool ( 10 ) and the workpiece ( 30 ), the grain of the tool, etc.

To select the adjustment parameters of the grinding process, the selected power requirement is determined to be less than or equal to the limit value. From this, the delivery and the relative feed rate are selected.

v:

Vorschubgeschwindigkeit in Lückenrichtung [mm/s]

Z_n(s):

Abtrag des Werkzeugs am Werkstück in Normalenrichtung [mm]

H'w_Gr:

Grenzwert des bezogenen Leistungsbedarfs (mm/s)

N(D_sls(s)):

Funktionswert in Abhängigkeit der Bogenlänge der Abwicklung s [mm].

k(s):

Korrekturfunktion, dimensionslos

The product of the removal and the relative feed rate results in too V · Z _n (s) ≦ H'w _Gr · π · N (D _SLS (s)) · / k (s) With

v:

Feed rate in gap direction [mm / s]

Z _n (s):

Removal of the tool on the workpiece in normal direction [mm]

H'w _Gr :

Limit of the required power consumption (mm / s)

N (D _sls (s)):

Function value depending on the arc length of the settlement s [mm].

k (s):

Correction function, dimensionless

This product is a function of the constant limit H'w _Gr , the correction factor and the dressing wheel diameter changing through the dressing. The value of the product is thus dependent on the total active surface of the grinding wheel ( 15 ). The interpretation takes place, for example, analogous to that in connection with the 6 - 10 described interpretation after the normal time chip volume.

If, after each dressing, the mathematical product is chosen to be less than or equal to the function value, 10 ) allows a large removal, while for a small grinding wheel ( 10 ) a critical adjustment or a grinding burn is avoided. Thus, a lower main time of processing can be achieved.

For example, according to the specification of the relative speed between the tool ( 10 ) and the workpiece ( 30 ), the radial delivery amount z. B. determined automatically. It is also conceivable to automatically set the relative speed for a given delivery amount. An optimization according to both parameters is also conceivable.

The prior art is that the grinding wheel is profiled for all strokes so that the end profile can be ground. As 3 As an example, Z _n (s) and thus the power requirement along the grinding wheel contour vary.

The grinding wheel ( 10 ) but can for example be profiled and / or positioned for some or each stroke so that the related maximum power requirement on the execution of the grinding wheel contour is reduced or constant. The selected related efficiency should be less than the limit.

LIST OF REFERENCE NUMBERS

4

technological limit Q'w _{nGr of} the purchased time span _volume ;

5

related time-wast volume Q'w

6

referenced normal-time chip volume Q'w _n

7

normal direction

8th

normal distance

10

Tool, profile grinding wheel, double cone pulley

11

Rotation axis, tool axis

12

central section

13

border area

14

border area

15

active area

16

lateral surfaces

17

End peripheral surface

18

Grinding wheel diameter d

21

axial feed direction

22

infeed

30

Workpiece, gear

31

Rotation axis, workpiece axis

32

gearing

33

Tooth flank, right flank

34

Tooth flank, left flank

35

oversize

36

teeth

37

gap

38

head

39

tooth roots

41

footer

42

head area

43

tooth root

44

finished size

45

Contour before grinding

46

tooth roots

51

dressing operations

b

Grinding wheel width

d

Grinding wheel diameter

Q'w

related time span volume

Q'w, gew

chosen Q'w

Q'w _n

referenced standard time chip volume

Q'w _n , gew

chosen Q'w _n

Q'w _nGr

technological limit value of the related standard time chip volume

s

Bow length, handling

V _gew

selected feed rate

Z _gew

chosen delivery

Claims (13)

Method for the design of a profile grinding process, characterized in that - for each profile point s, the development of the active surface ( 15 ) of the tool ( 10 ) from the normal direction ( 7 ) oriented removal of the oversize ( 35 ) of the workpiece ( 30 ) a required on the tool ( 10 ) and / or on the workpiece ( 30 determined power requirement is determined, - that the value thus determined is compared with a technological limit value, and - that the delivery amount and the relative feed rate between the tool ( 10 ) and the workpiece ( 30 ) are selected as a function of the workpiece geometry and / or the tool geometry so that the resulting power requirement is less than or equal to the technological limit value. A method according to claim 1, characterized in that from the removal of the oversize ( 35 ) of the workpiece ( 30 ), the geometry of the tool ( 10 ) and the relative feed rate between the workpiece ( 30 ) and the tool ( 10 ) on the tool ( 10 ) and / or on the workpiece ( 30 ) related power requirement is determined. Method according to Claim 1, characterized in that the delivery amount and the relative feed rate between the tool ( 10 ) and the workpiece ( 30 ) are selected in dependence on the workpiece geometry and / or the tool geometry such that their mathematical product multiplied by a correction function is less than or equal to the technological limit value. A method according to claim 1, characterized in that the removal is less than or equal to the maximum normal distance ( 8th ). A method according to claim 1 or 2, characterized in that the interpretation per stroke and / or stroke position takes place. A method according to claim 1, characterized in that the technological limit value is independent of the workpiece geometry and of the tool geometry. Method according to claim 1, characterized in that the correction function depends on the contact line between the tool ( 10 ) and workpiece ( 30 ). Method according to Claim 1, characterized in that the correction function depends on the swivel angle between the tool ( 10 ) and workpiece ( 30 ). A method according to claim 5, characterized in that the tool is profiled and / or positioned so that the related maximum power requirement on the execution of the grinding wheel contour is reduced or remains constant. A method according to claim 1, characterized in that the delivery amount and / or the feed rate is set automatically. A method according to claim 10, characterized in that after setting the delivery amount, the feed rate is set automatically. A method according to claim 10, characterized in that after setting the feed speed of the delivery amount is set automatically. A method according to claim 10, characterized in that after setting the ratio between feed speed and delivery amount, these two are set automatically.

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