DD248529A1 - METHOD FOR COMPENSATING CUTTING ERRORS - Google Patents

Abstract

The invention relates to a method for compensating toothing errors, resulting from eccentric clamping of the workpiece during processing a Teilwaelzverfahren. The aim of the invention is the restriction of toothing errors that result from incorrect clamping due to eccentric displacements, as well as a reduction in the manufacturing cost of clamping devices and the cost of Ausrichtaufwand. Taskgemaess the deviations of the gear center to the center of the rotary table of the gear cutting machine are taken as given and the error compensation during the rolling process by restoring the correct Verzahngeometrie done. In accordance with the method, in the clamping position of the workpiece, first of all, its eccentricity relative to the center of the rotary table is determined, and from this the size of additional movements determined, which are superimposed during the rolling movement of the latter. It is an additional movement for the Waelzweg and a correction movement for the partial movement provided.

Description

S _Z j = e (sin <^ _w - sin φ - ,) - e (cos φ - , - cos φ ^) tan a _s

and the correction movement (S _ti ) for the partial movement at the location of any tooth space number (i) the size

S _ti = e · sin φ \ - e (1 - cos ψ \) tan a _s

having.

5. Method according to item 1 or 1; 2 and 4 or 1, 3 and 4, characterized in that for the generation of the tooth profile (Z), the respective tangential velocity (V) in the center positions (E ₁ ) of the gear center (E) is used.

6. Method according to item 1 or 1; 2; 4 and 5 or 1; 3; 4 and 5, characterized in that in the processing of each edge in the vicinity of the selected center positions (E,) on the circle of radius e around the center (O) of the rotary table (2) a plurality of center layers (E _n ; E _i2 ; E _i3 ) are taken into account for determining the additional movement and the correction movement.

For this 6 pages drawings

Field of application of the invention

The invention relates to a method for compensating Verzahnungsfehlern arising from eccentric clamping of the workpiece during machining in part-rolling process, wherein between a tool with rack profile and the workpiece takes place a rolling movement, which consists of a linear, tangential to the pitch circle movement of the tool relative to the workpiece and a rotational movement of the workpiece about its axis.

Characteristic of the known technical solutions

With the variety of size and embodiment of gears is associated with an extensive range of clamping devices.

Thus, for hole qualities 6 and 5, three cylindrical mandrels are required solely for the overlap of the tolerance field, if a high gear quality is required.

The accuracy of these clamping devices and their clamping on the rotary table decisively influences the individual deviations of the toothing, such as concentricity deviation, total profile deviation, base circle deviation, total pitch deviation, etc.

Despite considerable expenses in the provision of accurate clamping means and their orientation on the machine is always to be expected with a residual value of the runout, which is either not at all or only with further considerable effort to reduce.

This residual value depends on the type of clamping means, such as mandrel tension or pot voltage, or whether cylindrical or

It is also crucial whether expansion mandrels or mandrels with intermediate sleeves are used. Universally usable mandrels, such as those with intermediate sleeves, have a wide range of applications, but for a greater concentricity of the recorded with this clamping device spur gear is expected.

Clamping cups are used for clamping mostly large gears or even those with large holes and small bore lengths.

In many cases, the pre-centering of these wheels takes place after sight with subsequent alignment to control collar. The higher the quality requirements placed on the gear, the higher the alignment effort. Spreader sockets are also used for final alignment in clamping jars. The larger the gears are, the more time-consuming is the alignment of these wheels and the more expensive are the alignment and centering aids.

According to DD-PS 89 556; B 24 B 5/28 a Bohrungsschleifeinrichtung is known, which is mounted on the workpiece carrier of a gear grinding in feed and feed guides and with which the bore of a tensioned on a clamping pot gear during the gear grinding or even thereafter to eliminate Aufspannfehlern is ground concentrically. The disadvantage of such devices is that either the simultaneous grinding of tooth flanks and bore mutual interference in terms of surface finish or when grinding successively increased time required.

Furthermore, such grinding devices for correcting Aufspannfehlern only possible at pot voltages, which ensure the accessibility of the receiving bore. Cogs that are clamped on a mandrel, therefore excrete for this process.

The mentioned gear errors result from the eccentric clamping of the gears on the rotary table of the gear cutting machine, wherein the center of the gear is offset from the center of the rotary table by the amount of eccentricity.

As a result, the position of the pitch circle with respect to the position of a rolling circle whose center coincides with the center of the rotary table, erroneously offset so that arise during the rolling deviations from the exact, theoretically accurate gear geometry. As a result, larger concentricity errors, single-part errors, edge shape errors and errors in the pressure angle arise.

Object of the invention

It is the object of the invention to reduce the toothing errors caused by tolerance ranges of the clamping means or by incorrect clamping due to eccentric displacement and to reduce the manufacturing costs of the clamping means by lowering the accuracy requirements, as well as to limit the workload for aligning the workpieces on the rotary table of the gear cutting machine.

Explanation of the essence of the invention

The invention has for its object to develop a method according to the field of application of the invention, in which the resulting from incorrect clamping deviation of the gear center to the center of the rotary table is taken as given and the error compensation takes place during the rolling process by restoring the correct Verzahngeometrie.

According to the invention this is achieved in that the eccentricity between the center of the rotary table and the center of the workpiece is determined in the clamping position of the workpiece on the rotary table of the gear, and in the execution of the toothing process of the rolling motion is given an additional movement, the amount of flank adapted to flank of the changed by the eccentricity Verzahngeometrie and each partial movement of the tooth gap to tooth space a corresponding correction movement is added.

According to a particular feature of the invention, the additional movement to the rolling motion, as well as the correction movement for partial movement in the linear, tangential to the rolling-circle-directed movement of the tool relative to the workpiece or added thereto.

According to a particular feature of the invention, the additional movement to the rolling motion, as well as the correction movement for partial movement in the linear, directed tangentially to the pitch circle movement of the tool relative to the workpiece or added thereto.

The additional movement to the rolling movement and / or the correction movement for partial movement may also be included in the rotational movement of the workpiece about its axis.

Further details of the invention, as well as the calculation bases for the determination of the magnitudes of the additional and correction movements can be seen from the exemplary embodiment.

embodiment

The invention is explained below with reference to an embodiment. In the accompanying drawings show:

1: The clamping position of a workpiece on the rotary table of the gear cutting machine,

2: the toothed geometric view of the clamping position, according to FIG. 1,

3 shows a continuation of the toothed geometric observation, based on FIG. 2, FIG.

4 shows a further toothed geometric observation,

5: the schematic distribution of different center positions of the workpiece,

Fig. 6: the schematic representation of the motion components in a coordinate system with the zero point in the middle

the round table,

Fin 7: a schematic representation of the rolling drive of a tooth flank grinding machine.

Fig. 1 shows the position of a gear 1, as it comes about by a faulty clamping on the rotary table 2 of a gear cutting machine when the gear center E does not coincide with the center O of the rotary table 2. The distance of the gear center E from the center O of the rotary table 2 is referred to as eccentricity e.

During the rolling process, the grinding wheel 3 of the tooth flank grinding machine on which the example is based grinds the tooth profile Z. In the rolling process, the rotary table 2 rotates about its center O, this rotation being assigned the rotation angle cp _w

At the same time, the grinding wheel 3 performs a rectilinear movement s relative to the center O of the rotary table 2. The radius r in Fig. 1 is the gear 1 associated Wälzkreisradius. The pitch circle w is the circle whose point velocity at the pitch point C due to the rotation about the center O coincides with the velocity due to the movement s.

Usually, however, the machine side, the movements are coordinated so that the velocities due to the rectilinear movement s and the rotational movement about the center O at the pitch point C match.

The point C, is the pitch point which lies on the faulty pitch circle W _f with pitch circle radius r about the center O (FIG. 2).

If the gear 1 is rotated by the rotation angle cp _w , so that the Wälzpunktlage C _f migrates to A _f , so shifts relative to the grinding body 3 with its cutting edge k from the cutting edge position k ₀ after the cutting edge position k _t .

The displacement C _f A _g is equal to the arc C _f A _f . The associated engagement point N moves in response to these movements in the engagement point position N _f .

In reality, however, the gearwheel 1 associated with the rolling circle W is concentric with the gear center E, which describes a circle with the radius of the eccentricity e on rotation about the center O of the rotary table 2. In order to generate the profile of the gear 1 with the cutting edge k properly, the grinding wheel 3 must perform with its cutting edge k in addition to the movement s an additional movement s _z , which compensates the circular motion of the gear center E about the center O of the rotary table 2. Even in the starting position, the pitch point C must not take the pitch point C _f , but he must be on the gearwheel 1 associated pitch circle W. The speeds due to the rotation about the center O and the rectilinear movement s must then be equal even in the pitch point C.

Due to the eccentric movement of the rolling circle W, the rolling point C assigned to it also performs a corresponding eccentric movement. In the middle position E _{w of} the gear center E, the pitch point C also assumes the adjacent pitch point C _w . Here, the sheets EE _W and CC _W coincide identically.

The cutting edge k has, based on the starting position in the adjacent position of the gear 1, the cutting edge position k _{w taken} by point P. The distance C _W P is equal to the arc C _W A _W , which is traversed by E _w upon rotation of C ". The correct point of engagement between gear 1 and grinding wheel 3 is then given by the engagement point position N _w .

It can be seen from these representations that deviations from the exact values for pressure angle, engagement division, profile shape, concentricity and with respect to the tooth width also deviate from the exact values for the flank line in the conventional production method.

There are staggering deviations on the circumference of the wheel, which are also reflected in a total deviation of the pitch. From Fig. 2 it can be seen that even in the starting position, a faulty pressure angle and a faulty tooth profile Z, is generated, since this is the valid point of intervention N between k and Zf.

In the exact production of the tooth profile Z, the following components of motion occur:

First, the movement of the gear center E to E _w and thus of the pitch point C to C ^ _n and secondly the rotation of the gear by rotation angle cp _w based on the adjacent position E _w to gear center E.

The rotation of the gear 1 to the rotation angle cp _w is part of the rolling motion used in the conventional procedure.

With the mentioned components of motion, the cutting edge k moves firstly from k ₀ to k, and secondly from k, to

From Fig. 2 it can be seen that it is completely unimportant on which way the cutting edge k, the cutting edge position k, has taken. This offers the possibility to compensate for the circular motion of the pitch point C to C "solely by a linear movement s, in such a way that after the movement component of the pitch point C to C _w the cutting edge k then also due to the corrected movement s through C _w is ok. It follows that the gearwheel 1 associated with pitch circle W exact rolling motion can be realized with two numerically controlled axes.

In FIG. 3, in contrast to FIG. 1, an arbitrary initial position of the gear center E is indicated by the center position E _{ . This includes the pitch point Cj.

If Ej travels to E "due to the rolling motion, then C ₁ also shifts to C _w and C _w to A _w .

As a result of the eccentricity e is dependent on cp _w next to the previously applied motion s of the size

s = r (cp _w - cpi) in the processing of any tooth flank in a tooth gap with the tooth gap number i an additional movement s _z of the size

s _2i = QG "- Hü or Sii = e (sin cp _w - sin Cp ₁ ) - e (cos φ, - cos cp _w ) tan a _s

required so that s _g results as the total rolling path:

Sgi = S + S _zi .

However, it is not only these Wälzwege with the associated Wälzverhältnissen when editing the tooth flanks along the circumference of the gear, but also the amount of pitch from tooth gap to tooth gap with progressive processing of the gear 1. This pitch change can also be by a change in the position of the cutting edge k in Compensate the direction of movement s, based on the individual tooth gaps on the circumference of the wheel. In the partial movement of the tooth gap to tooth gap an additional displacement of the bed carriage of the tooth flank grinding machine by a correction movement s _{ti is} required. It has the size for any number of teeth i:

s _ti = UM - EM "or s _ti = e · sincpi-e (1 - οοβψί) tanot _s

where a _{s stands} for the prewarning angle and i as the number of tooth spaces depending on the number of teeth ζ of the gear 1, the values

i = 1; 2; 3 ... Z-1 can accept.

For the rolling ratio to be represented on the machine side, a reference circle B with the radius r _{B is} assigned to the rotary table 2. In special cases, this may also be the pitch of the rotary table 2 associated Teilschneckenrades. Depending on the Wälzbzw, even partial movement of the reference circle B in each case the bow b _w or b _{covered . Thus:

⁶ W, ^b i

φ «= - or φ, = -, Γβ r _B

For the rolling ratio, the paths traveled in the time unit on the rolling circle W and the reference circle B (FIG. 3) are decisive. Again, compared to the usual manufacturing process, an additional amount occurs, which is caused by the instantaneous tangential velocity v "of the point E _w .

The tangential velocity v _w is decomposed into the components v, and v ₂ .

The previous rolling ratio I is:

and the additional:

w ^v U = - (cos φ "- sin cp _w tan a _s)

^r B

so that in total results:

I ™ = - + - (cos φ ^ - sin φ ^ tan a ₅ ) Γβ r _B

For the preparation of the tooth profile only a small arc portion on the circle with the eccentricity e (Fig. 2) is effective. It can therefore be the respective tangential velocity ν in the middle positions

and the angles of rotation

<Pi ⁼ (<Pi '<P2. Φ3 ··· φζ-ΐ)

used for generating the profile.

Thus, practically the circle with the radius of the eccentricity e is enveloped by tangents which, at the spacing of the graduation, touch this circle in the center positions E (FIG. 5).

The whole problem then simplifies considerably, because for each tooth profile of successive tooth gaps another, but constant rolling speed is applicable. It has for the respective center position Ej of the gear center E the size:

l _ai = - + - (cosφι - sin cpj tan cc _s )

r _B r _B

The method according to the invention can be carried out on all gear cutting machines which work with rack profile-equipped tools in the single-part rolling process. Since particularly high accuracy requirements occur in particular during tooth flank grinding, the method sequence for an NC-controlled tooth flank grinding machine is set out below.

FIG. 7 shows the workpiece carrier of a tooth flank grinding machine. The grinding wheel 3 is connected to a not shown tool carrier and performs tangential to the gear 1 no movements. The rolling movement takes place by the rotation of the rotary table 2 to the middle 0 and by the linear movement s of the bed carriage 4, in which the rotary table 2 is mounted

The bed carriage 4 is driven on a bed 5 by means of the servomotor 6 via the threaded spindle 7 and the rotary table 2 receives its rotation from the servomotor 8 via worm 9 and worm wheel 10.

Both the servomotor 6 and 8 each have a tachogenerator and an angle measuring 11; 12 assigned.

The two angle measuring 11; 12 are via a computer controller 13 with actuators 14; 15 linked, in turn, with the servomotors 6; 8 are in operative connection.

Before the beginning of grinding, the eccentricity e of the clamping position is determined during one revolution of the rotary table 2 at the bore or a test collar 16 of the gear 1 and thus registers the position of the gear center E. (Figure 6).

In general, the tooth profile Z (FIG. 4) does not pass through the pitch point C. In order to determine the position of the gear center E at the point of intersection of the tooth profile Z with the pitch circle W, the head edge first grinds.

(Point K in Fig. 4). With the grinding of the head edge of the eccentric angle φι, determined.

Now the gear 1 is turned back far enough that the tooth profile Z from the tooth profile Z _k assumes the position Z _c and through the

-5- Z48 5Z9

Wälzpunktlage C _k goes. The angle by which the gear 1 is rotated back is ε. It results from turning a flank point F from the flank point position F _k by E _k into the position F ₀

The point F _k migrates here on the base circle G (FIG. 4)

The sheet F _c F _k has the amount:

FcF _k = r _g (tanct _k -tana _s ) and the angle ε results in:

Thus, the starting position for machining by the positioning of the gear center E in the gear center position E _{0 is set} on the circle with the radius of eccentricity e. The associated rotation angle cp _{0 of} the rotary table 2 results in:

(Po = (Pk-ε.

Starting from this reference rotation angle φ ₀ with tooth center position E ₀ , the grinding of the tooth profile Z with changed rolling speed from tooth gap to tooth gap and the changed delivery of the bed carriage 4 or rotary table 2 from pitch to pitch is carried out as follows:

In the computer control 13, an electronic eccentric is realized, to which the degree of eccentricity e is assigned. The eccentricity e is in the coordinate system X; Y, which is built in the center O of the rotary table 2 (FIG. 6), depending on the angle of rotation Φι, divided into the two components OY and OX, the ordinate subsequently receives a scale change with the factor tan ct _s .

For each division by the angle of rotation φ-, the bed carriage 4 performs by means of this electronic eccentric an additional movement ÜX and YE ₀ , taking into account the scale change for the ordinate.

For the required additional rolling, the same eccentric is used with a scale change around tan a _s for the X-axis. This is oil? subtracted from ÜY and set the result in relation to the reference circle radius. If the initial position of the toothed wheel 1 for grinding the first flank Z with respect to the center of the tooth E or the pitch point C (FIG. 4) differs by the angle of rotation φ ₀ , then in each case φ- changes by the angle of rotation cp ₀ .

The technical-economic effect of the invention is due to the fact that gear errors resulting from inaccurate clamping can be largely reduced without increasing the accuracy of the Aufspannmittel in an uneconomical manner. This effort can be reduced to a minimum, contrary to all previous ideas, resulting in a reduction in manufacturing costs, including the costs, which are indispensable for the teaching provision in a higher fit quality.

Claims (4)

Invention claim: 1. A method for compensating Verzahnungsfehlern resulting from eccentric clamping of the workpiece during machining in the Teil- Wälzverfahre η, wherein between a tool with 'rack profile and the workpiece takes place a rolling movement, which consists of a linear, tangential to the pitch circle movement of the tool relative to the workpiece and a rotational movement of the workpiece about its axis, characterized in that in the clamping position of the workpiece (1) on the rotary table (2) of the gear cutting machine, the eccentricity (e) "between the center (0) of the rotary table ( 2) and the center (E) of the workpiece (1) is determined, and in the execution of the toothing process of the rolling motion is given an additional movement whose amount is adapted from edge to edge of the eccentricity (e) changed Verzahngeometrie, and each partial movement from tooth space to tooth gap a corresponding correction movement is added. 2. The method according to item 1, characterized in that the additional movement (s _zi ) to the rolling movement and the correction movement (s _ti ) for partial movement in the linear, tangential to the pitch circle movement of the tool (3) relative to the workpiece (1) is included , 3. The method according to item 1, characterized in that the additional movement to the rolling movement, and the correction movement for partial movement in the rotational movement of the workpiece (1) is contained about its axis. 4. The method according to item 1 and 2, characterized in that the additional movement (S _z ) for the rolling movement for any tooth space number (i) the size