EP1590126B1 - Method for calibrating a grinding machine - Google Patents

Abstract

The invention relates to a method for calibrating a grinding machine for sharpening bar blades by grinding at least two flanks and a top surface (K) of the bar blades, involving the following steps: producing a calibrating blade by sharpening a bar blade according to predetermined dimensions; measuring the dimensions of the calibrating blade, and; calibrating the machine with the aid of at least the measurement result. In order to produce a calibrating blade, the bar blade is, in at least two steps, ground on the flanks and on the top surface (K) in a complete calibrating grinding. The inventive method is advantageous in that the calibrating blade is ground under the same conditions as a production blade so that process-related influences, in particular, displacements associated with the grinding forces, can also be taken into consideration.

Description

• Herstellen eines Kalibriermessers durch Schärfen eines Stabmessers entsprechend einer vorgegebenen Geometrie,
• Messen der Geometrie des Kalibriermessers, und
• Kalibrieren der Maschine mit Hilfe des Messergebnisses.

The invention relates to a method for calibrating a grinding machine for sharpening bar knives by grinding at least two flanks and a top surface of the bar knives, including the steps

• Making a caliper by sharpening a bar knife according to a given geometry,
• Measuring the geometry of the caliper, and
• Calibrate the machine using the measurement result.

Such a calibration method is known from the OERLIKON B24 MESSERSCHLEIFMASCHINE OPERATING MANUAL, Date of Issue 03.09.1999 / B, Oerlikon Geartec AG, Zurich, which was supplied to VW Kassel with the machine No. 289839. The contents of these operating instructions (abbreviated to BA below) and in particular the parts of the same cited below are hereby incorporated in full into the present description.

The aforementioned calibration method has been developed for a 5 + 1 NC-axis grinder, as shown in BA, page 9, and, for ease of reference, in the appended FIGURE. With such a grinding machine, cutting tools such as a bar blade 10 shown in the accompanying Figs. 2 and 3 are sharpened by means of a grinding wheel 12. The grinding machine has a table 17 on which a carriage 18 is movable back and forth along an X-axis. A column 19 is reciprocable along a Z-axis perpendicular to the X-axis. On the column 19, a carriage 20 is further reciprocally movable along a Y-axis perpendicular to the X-axis and the Z-axis. The X-axis, the Y-axis and the Z-axis form a rectangular coordinate system. On the carriage 20, the grinding wheel 12 is rotatably mounted. On the carriage 18, a tensioning device 21 for tensioning the blade 10 is attached. The tensioning device 21 is mounted relative to the carriage 18 by a positioning axis CC and a positioning axis AA perpendicular to the positioning axis CC. The X-axis, the Y-axis, the Z-axis, the positioning axis AA and the position axis CC can not only position but also drive CNC controlled trajectories.

According to the attached Fig. 2, the bar blade 10 has a rectangular cross-section shaft 2 and a longitudinally substantially trapezoidal end 3. At the end 3 are a rake face C, on a in Fig. 2 left flank 5 a from the rake face C to the rear side extending auxiliary free surface B, on a right in Fig. 2 flank 6 a of the rake face C to the rear extending main flank A and the top of the face a from the rake face C to the rear extending head face K formed. Between the secondary flank B, the top surface K, the main flank A and the rake face C a circumferential cutting edge 4 is formed. In the transition from the main flank A and the secondary flank B to the shaft 2, as shown here, shoulder surfaces A _S and B _{S may be} formed. Likewise, in the transition region of the rake surface C to the shaft 2, as shown here, a curved shoulder surface C _{S be} formed. The main flank A, the side flank B and the rake face C each have a facet A _F , B _F and C _F, respectively. The facet angles are about 1 ° and are designated in the attached FIG. 3 with γ _AF , γ _BF and γ _CF (where γ _{BF is} not visible in FIG. 3).

In Fig. 4, a grinding wheel 12 is shown with which the bar blade 10 can be ground. The grinding wheel 12 has an axis of rotation S, to which the grinding wheel is rotationally symmetrical. The grinding wheel 12 has a circular clamping surface 13 at right angles to the rotation axis S on one end side. From the outer periphery of the clamping surface 13, there extends a tapered grinding surface Pp having a small diameter d1 and a large diameter d2, with the small diameter d1 the clamping surface 13 is located. On the side with the large diameter d2 of the tapered grinding surface Pp is tangent to a radius Rs having curved grinding surface 14, which in turn merges tangentially into a cylindrical grinding surface Ps. The cylindrical grinding surface Ps is adjoined tangentially by a toroidal grinding surface G, which has a circular arc-shaped cross section with a radius of curvature Rg. The toroidal grinding surface G extends radially inwards and merges tangentially into a second conical surface 15 which is undercut relative to the toroidal grinding surface G. The grinding wheel 12 is a diamond wheel with galvanic bonding of the diamond abrasive grains. The position of the grinding wheel 12 (more precisely, its finishing edge) in the direction of the Y and Z axes are indicated in FIG. 4 by pY or by pZ.

The attached Figs. 5 and 6 show the tensioning device 21 in front view and in plan view, respectively. The tensioning device 21 is rotatable about the positioning axis C-C and pivotable about the positioning axis A-A. In the tensioning device 21, a left bar blade 10 is clamped, as shown, or a right bar knife. The tensioning device 21 has two stop surfaces 23, 24 for left and right bar blades.

For the sharpening of bar knives on the grinding machine, the production grinding and the dual grinding process are used. The described grinding wheel 12 also allows shaping grinding (roughing) and subsequent generating grinding (finishing) of the surfaces of the bar blade 10, without this having to be re-clamped. The grinding wheel 12 expediently rotates about the stationary axis of rotation S, and the bar knife to be sharpened is guided under adjustment to corresponding angles on the grinding wheel 12. The dual-grinding method for bar knives and a grinding wheel for carrying out the method are described in WO 02/058888 A1, to which reference is made in order to avoid repetition.

From DE 29 46 648 C2 discloses a method for profiling and sharpening bar knives is known in which only one operation for a complete cut is required.

The purpose of the above-mentioned calibration is to determine after a change of the clamping device 21 or the grinding wheel 12 occurring deviations due to manufacturing and assembly inaccuracies and in the sharpening of bar knives both for the calculation based on nominal data and the current lstzustand the grinding machine to take into account the calibration. Calibration is also recommended after prolonged use of the grinding wheel in order to compensate for wear-related displacements (due to increased grinding forces).

• Abstand der beiden Anschlagflächen 23, 24 zur Positionierachse C-C der Spannvorrichtung 21 (Fig. 5 und 6):
  • Anschlag für linke Messer   (aL)
  • Anschlag für rechte Messer   (aR)
• Position der Schleifscheibe 12 (Schlichtkante) in zwei Achsrichtungen (Fig. 4):
  • Y-Achse   (pY)
  • Z-Achse   (pZ)
• zusätzlich: Abmessungen der (Dual-)Schleifscheibe (Fig. 4):
  • Rundungsradius der Schlichtkante   (Rg)
  • Abstand zur Schruppfläche   (Ps)

The following are important for the calculation of the grinding path:

• Distance between the two abutment surfaces 23, 24 to the positioning axis CC of the tensioning device 21 (FIGS. 5 and 6):
  • Stop for left knife (aL)
  • Stop for right knives (aR)
• Position of the grinding wheel 12 (finishing edge) in two axial directions (FIG. 4):
  • Y axis (pY)
  • Z axis (pZ)
• additionally: Dimensions of the (dual) grinding wheel (Fig. 4):
  • Rounding radius of the finishing edge (Rg)
  • Distance to the roughing surface (Ps)

The known calibration method is described in detail in BA, pages 97-108, to which reference is made to avoid repetition.

In this known calibration method, a calibration gauge with fixed geometry is made on three surfaces for the grinding machine and delivered with the grinding machine. The three surfaces are the main flank A, the minor flank B and the top surface K. A calibrating blade is ground in three steps or grinding phases in the machine, in accordance with the calibration gauge.

1st grinding phase

The knife is clamped in the clamping device 21 with the aid of a gauge block. Then the clamping height is measured in the machine (BA, page 100, point 6).

The top surface K is ground and measured in the clamped state of the knife in the machine (page 103).

The measured value is input to the controller. It causes a correction in the Y axis (BA, page 104, point 11).

2nd grinding phase

The bar knife 10 is ground in a horizontal position (BA, page 104, point 14). The knife height is again measured in the machine (BA, page 105, item 17). Again, the measured value is entered into the control (BA, page 105, point 19).

3rd grinding phase

The machine grinds the main flank A or flank 6 and the secondary flank B or flank 5 (BA, page 106, point 21).

Then the two open spaces A and B are measured outside the machine (BA, page 106, point 1) and compared with a calibration gauge (a so-called master gauge). The measured values, i. the deviations are in turn entered into the controller. Thus the machine is calibrated and set up

The process is time consuming. Measuring in the machine is difficult and requires a lot of practice. In the first two steps (1st and 2nd grinding phases), the grinding wheel oscillates over the top surface, representing a grinding process involved in the production process, i. does not occur when sharpening bar knives on the grinder. Furthermore, the known method requires three steps or grinding phases, namely the first and the second grinding phase in which the top surface is ground twice to detect the Y and Z components of a defect, and a third grinding phase in which the two flanks once sanded to determine the fixture position to the CC axis. The knife can not be removed from the machine during the first two steps of the measurement, as it is measured relative to the machine in these steps. A jig error can therefore be determined in the known calibration method only in the third grinding phase. This means that the first and the second grinding phase can subsequently prove to be superfluous because their results can not be used at all due to an initially unrecognized clamping device error. Finally, the previous dual process calibration procedure is either too inaccurate or requires additional machinery.

The object of the invention is to provide a method of the type mentioned in such a way that it is easier to carry out and provides better results.

This object is achieved by the method according to claim 1.

The procedure for calibrating a grinding machine is carried out by means of a calibrating knife, which, unlike the known method, is ground in fixed positions and subsequently measured outside the machine. The measured deviations from the nominal dimensions are entered into the NC control of the grinding machine and taken into account there in a suitable manner. While grinding a production knife, this is also measured outside the machine, but a correction is made only for one axle assembly (by moving the knife). The grinding machine itself could not be calibrated by such a single correction.

The Kalibriermesser that is produced, as in the known method consists of a rectangular rod on which a top surface K and two open spaces A, B are sanded. They form with the front bar surface the knife edges, the intersections of the top edge with the flanks the knife tips. The normal grinding process for making a production knife involves grinding a bar knife on the flanks and head face once completely. In order to produce a calibrating blade, according to the invention, a bar knife is completely ground at least twice and measured outside the machine after each of these two calibration cuts. Deviations are entered into the machine control, as in the known method also. The grinding process of the calibrating blade is the same in the method according to the invention as in a production knife. This is why technological features in the machine are included in the grinding result. This is the most important advantage of the calibration method according to the invention over the known calibration method. According to the invention, the production process is reproduced with a geometrically exact arrangement during the calibration. But also the measuring method agrees with that used in the production. However, in the method according to the invention, an approximately existing jig error is already determined in the first grinding phase, in the known method, however, only in the third grinding phase. Further important advantages of the method according to the invention are that no measurement is carried out in the machine at all and that the method according to the invention comprises only two calibration cuts in total, in contrast to the known method which comprises three calibration cuts. In the method according to the invention, since the measurement of the geometry of the calibrating blade is carried out on a measuring device outside the grinding machine, the measuring process can be adapted more closely to a production process of bar knives, which is also measured on a measuring device outside the grinding machine.

Advantageous embodiments of the method according to the invention form the subject of the dependent claims.

If, in one embodiment of the method according to the invention, each calibration cut contains two finishing passes, the calibrating knife is finished after two complete calibration cuts.

If, in a further embodiment of the method according to the invention in the two calibrations the bar blade is aligned in two axial directions forming an angle of 70 ° - 90 ° and preferably 90 ° to each other, the position of a working surface of a grinding wheel of the grinding machine with respect to these two Axial directions and the orientation of the bar blade to determine a positioning axis, so can be easily eliminated three errors in two steps.

In a further embodiment of the method according to the invention in the first finishing pass in one go, the top surface, a first transition radius to the first flank and the first flank are ground, then the bar blade is rotated through 180 ° about the positioning axis and subsequently in the second sizing pass the head surface, a second transition radius to the second flank and the second flank are ground, obtained advantageously when grinding each flank at each calibration cut the bar knife a different arrangement in the grinding machine, so that a clear inference of the measured values on the calibration values is possible, and This results in a symmetrical geometry of the Kalibriermessers for calibrating. Since it is possible to change between right and left stop from the first to the second calibration cut, a total of four errors can be eliminated in two steps.

If, in a further embodiment of the method according to the invention for the first Kalibriersohliff the bar blade is arranged to the end face of the grinding wheel, can easily determine a fault in the direction of the Y-axis, if in this embodiment, the knife is arranged frontally to the grinding wheel so that the AA axis is as parallel as possible to the Y axis and that the stop surface of the clamping device is exactly parallel to the X axis. In the first finishing pass, head face, transition radius and the first flank are ground in one go. If, for the second finishing pass, the knife is rotated by 180 ° about the CC axis with the clamping device and the same grinding process is repeated, the head face, transition radius and the second flank are now ground.

The grinding wheel is thereby guided rectilinearly along the edges so that the head surface is perpendicular, both flanks opposite at a predetermined angle (preferably 20 °) to the C-C axis and the blade tips receive the distances to be tested (mA and mB) to the stop surface.

In a further embodiment of the method according to the invention for the second Kalibrierschliff the bar blade is rotated by 90 ° and arranged to the cylinder side of the grinding wheel by the device is rotated 90 ° about the AA axis, so that the CC axis is now parallel to the Z Axis, it is possible to determine an error in the direction of the Z-axis, otherwise the procedure is exactly the same as for the first calibration cut.

In a further embodiment of the method according to the invention for determining the radius of curvature of a grinding wheel of the grinding machine, the positioning axis of the bar blade is inclined by the flank angle and the bar blade is completely ground in a third calibration cut on the flanks and the top surface, the measured deviation gives a third Circle point from which a deviation of the rounding radius Rg can be calculated via a program.

If, in a further embodiment of the method according to the invention for calibrating the grinding machine by a further step, one of the two edges of the bar knife only with a roughing surface of the grinding wheel whose position is to be determined is ground, the distance to the roughing surface Ps by the further step determine by just roughing the second flank without facet angle. The first flank serves as a control. The evaluation is again via a program.

If, in a further embodiment of the method according to the invention, an absolutely measuring measuring device is used for measuring the geometry of the calibrating blade, the measurement can be tactile or optical in order to measure the deviations of the flanks or tip distances (fmA and fmB) after each grinding. The evaluation can be carried out again via a program in the computer of the grinding machine.

If in a further embodiment of the method according to the invention for measuring the geometry of the Kalibriermessers a comparatively measuring device is used which compares the measured geometry of the Kalibriermessers with the dimensions of a Kalibrierlehre, the process can be accelerated because the comparison measurement usually faster and more accurate than an absolute measurement is, however requires a calibration gauge, which was previously measured accurately via an absolute measurement.

In a further embodiment of the method according to the invention, in the steps in which the bar knife is ground in a complete calibration grinding, the grinding is carried out under the same conditions under which bar blades are sharpened on the grinding machine, the calibration can be with the same method as grind a production knife, so that also process-related influences, in particular with the grinding forces associated displacements, are taken into account. Calibration over three axes (Y, Z, C) not only adjusts the position and symmetry of the flanks on the knife, but also the grinding rate. This makes the knife insensitive to directional variations of the C-C axis. This also avoids form errors in the tip radius (due to offset of the top edges) and differences in the facet removal

Fig. 1

eine perspektivische Ansicht einer bekannten Schleifmaschine zum Schärfen von Stabmessern, die sich durch das Verfahren nach der Erfindung kalibrieren lässt,

Fig. 2

eine perspektivische Teilansicht eines Stabmessers, das sich mittels der Schleifmaschine nach Fig. 1 schärfen lässt,

Fig. 3

eine Teilquerschnittansicht des kopfseitigen Endes des Stabmessers nach Fig. 2 zur Veranschaulichung von Facetten- und Freiwinkeln im Bereich einer Schneidkante,

Fig.4

eine Schnittansicht einer Schleifscheibe der Schleifmaschine nach Fig. 1,

Fig. 5

eine Vorderansicht einer Spannvorrichtung, die mit einem eingespannten Stabmesser dargestellt ist,

Fig. 6

in Draufsicht die Spannvorrichtung nach Fig. 5,

Fig. 7

die Auswirkung eines Positionsfehlers der Schleifscheibe auf ein Produktionsmesser,

Fig. 8

die Auswirkung des Positionsfehlers in Richtung des Messerschaftes,

Fig. 9

die Auswirkung der Abweichung einer Anschlagfläche bei dem Schleifen der Hauptfreifläche A und der Nebenfreifläche B eines Stabmessers (linkes Messer),

Fig. 10

einen ersten Kalibrierschliff, stirnseitig, zur Kompensation einer gemessenen Abweichung fm = fpZ und

Fig. 11

einen zweiten Kalibrierschliff, zylinderseitig, zur Kompensation einer gemessenen Abweichung fm = fpY, nachdem die Abweichung fpZ gemäß Fig. 10 kompensiert worden ist.

Embodiments of the invention will be described in more detail below with reference to the remaining drawings. Show it

Fig. 1

a perspective view of a known grinding machine for sharpening bar knives, which can be calibrated by the method according to the invention,

Fig. 2

a perspective partial view of a bar knife, which can be sharpened by means of the grinding machine of FIG. 1,

Fig. 3

2 shows a partial cross-sectional view of the head-side end of the bar cutter according to FIG. 2 for illustrating facet and clearance angles in the region of a cutting edge,

Figure 4

1 is a sectional view of a grinding wheel of the grinding machine according to FIG. 1,

Fig. 5

a front view of a tensioning device, which is shown with a clamped bar knife,

Fig. 6

in plan view, the clamping device of FIG. 5,

Fig. 7

the effect of a positional error of the grinding wheel on a production knife,

Fig. 8

the effect of the position error in the direction of the measuring shaft,

Fig. 9

the effect of the deviation of an abutment surface during the grinding of the main flank A and the secondary flank B of a bar knife (left knife),

Fig. 10

a first calibration cut, end face, to compensate for a measured deviation fm = fpZ and

Fig. 11

a second calibration cut, cylinder side, to compensate for a measured deviation fm = fpY, after the deviation fpZ has been compensated according to FIG.

When grinding in the generating method, as illustrated in the attached Fig. 7, positional deviations of the grinding wheel (fpY, fpZ) and a stop deviation in the jig (fa = faL or faR) affect both the flank abrasion (fb) and the removal over head (fh) (and the two top edges can be offset). In the comparison measurement, the master knife in the measuring device is shifted from the desired position against the stop (by fh), so that the measured thickness deviation (fm) results as a superimposition of all errors. This measured value has hitherto been used to correct the knives.

Principle of the known calibration method:

The basic idea of this calibration procedure is to decompose the total error into individual components and compensate them separately. This will now be described with reference to the accompanying Figs. 7 to 9 in more detail.

If one considers only the component in the direction of the CC axis (fpC, FIG. 7, analogous fpY, FIG. 8) of the positional discrepancies (vector fp, FIG. 7) of the grinding wheel 12, it causes the head and flank to move around the same amount (fh = fpY) staggered offset. Seen in the direction of the knife blade thus only the Abschliffhöhe changes, whereas the geometry of the finished ground knife remains unchanged. This effect is used to separate the single errors as follows:

When aligned with the Y axis, the measured deviation (fm) is equal to the Z component (fpZ), when aligned with the Z axis it is equal to the Y component (fpY) of the position deviation. Assuming that both flanks of the knife were ground with the same direction of the C-C axis, the top edges have the same offset and the peak distances of the two flanks A and B have the same deviation (fmA = fmB). The deviation of the stop surface (fa = faL or faR) is superimposed. It causes a positive deviation on one edge, a negative deviation on the other edge (FIG. 9), but no offset of the top edges. By difference and mean then stop and position deviation (as described below) can be separated.

For the second position component, the knife must be ground again. This can also be changed to the second stop surface. Although the knife has to be ground and measured twice, this results in a very simple and effective calibration method.

Evaluation:

To calibrate the disc position, deviations (f = actual value - nominal value) are determined with which the nominal values used for the calculation of the grinding path are adapted to the actual values (not vice versa!). right stop (Difference) faR = (fsB - fsA) / 2 for right knives left stop (Difference) faL = (fsB - fsA) / 2 for left knives Z position (Average) fpZ = (fsB + fsA) / 2 for Y alignment (front side) Y position (Average) fpY = (fsB + fsA) / 2 for Z registration (Cylinder side)

Method according to the invention

In the method according to the invention for calibrating a grinding wheel, the bar blades 10 are ground completely at least twice. Each calibration cut contains two finishing passes, which will be described in more detail below with reference to FIGS. 10 and 11.

First calibration cut (Y-alignment, Fig. 10):

For the first finishing pass, the bar blade 10 is arranged on the front side of the grinding wheel 12 so that the A-A axis is as parallel as possible to the Y axis and that the stop surface 23 of the clamping device 21 is exactly parallel to the X axis. In the first finishing pass, the head face K, a transition radius and the first flank are ground in one go.

For the second sizing pass, the bar cutter is rotated by 180 ° about the C-C axis by means of the tensioning device 21, and the same grinding operation is repeated, so that again the head face K, another transition radius and the second flank are ground.

The grinding wheel 12 is thereby guided along the edges so that the head face K is perpendicular, that both flanks 5, 6 opposite to each other at a predetermined angle, preferably 20 ° to the CC axis and that the blade tips to be tested distances mA and mB to Stop surface 23 or 24 obtained.

When using a dual grinding wheel, the C-C axis must be inclined by a small angle in the inventive method for design reasons. Together with the facet removal deviation, the first calibration step produces a feedback between the Y and Z components, which can lead to a residual error (between 5% and 20% of the second component). For larger deviations, therefore, a check should be carried out with a possible recalibration. An offset of the top edges is avoided by both flanks are ground with the same axis arrangement.

In the dual process, the edges preferably receive the same facet as the production knives. The fact that the top surface is ground twice with every complete cut is geometrically meaningless, but technologically necessary. During the first finishing pass, a large oversize must be ground off, which can lead to a form error of the head edge. In the second finishing pass, however, this error is eliminated.

Second calibration (Z-alignment, Fig. 11):

The procedure is exactly as in the first cut, but the knife is placed on the cylinder side of the grinding wheel 12 by the clamping device by 90 ° is pivoted about the AA axis so that the CC axis is now parallel to the Z axis. From the first to the second calibration grinding, you can switch between right and left stop.

The evaluation is carried out in the manner already described at the outset by determining deviations (f = actual value nominal value) for calibrating the slice position with which the nominal values used for the calculation of the grinding path are adapted to the actual values, as in the prior art Technique, where differences and averages are also calculated in the way outlined above.

Further calibration options:

After the disc position has been precisely calibrated, the most important dimensions of the grinding wheel can be checked and adjusted if necessary:

Rounding radius Rg:

The bar knife 10 is ground a third time, the C-C axis is inclined by the flank angle, so that the flank is now vertical. The measured deviation results in a third circle point from which the radius deviation can be calculated via a program.

Distance to the roughing surface Ps:

In a further grinding pass, the second flank is only roughed without facet angle. The first flank is for control. The evaluation is again via a program.

Claims (11)

1. A method of calibrating a grinding machine for the sharpening of bar cutting blades (10) by grinding at least two flanks and a top surface of the bar cutting blades, comprising the steps of:

   - producing a calibrating blade by sharpening a bar cutting blade (10) to a predetermined geometry,

   - measuring the geometry of the calibrating blade, and

   - calibrating the machine with the aid of the measurement result,

   characterized in that the manufacture of a calibrating blade includes the complete grinding of the bar cutting blade (10) at least twice on the flanks (5, 6) and the top surface (K), and that the measurement of the geometry of the calibrating blade is taken on a measuring device outside the grinding machine.
2. The method according to claim 1, characterized in that each calibrating grind includes two finishing passes.
3. The method according to claim 2, characterized in that the two calibrating grinds involve the step of orienting the bar cutting blade in two axis directions (Y, Z), forming an angle of between 70° and 90° and preferably of about 90° with one another in order to determine the position of a working face of a grinding wheel of the grinding machine relative to these two axis directions and the orientation of the bar cutting blade relative to a positioning axis (C-C).
4. The method according to claim 3, characterized in that the first finishing pass comprises grinding the top surface, a first transition radius to the first flank and the first flank in a single pass, whereupon the bar cutting blade is rotated about the positioning axis (C-C) through 180 degrees, and that the subsequent second finishing pass comprises grinding the top surface, a second transition radius to the second flank, and the second flank.
5. The method according to claim 4, characterized in that for the first calibrating grind the bar cutting blade is positioned against the end face of the grinding wheel.
6. The method according to claim 5, characterized in that for the second calibrating grind the bar cutting blade is swung through an angle of 90 degrees and positioned against the cylinder face of the grinding wheel.
7. The method according to any one of claims 3 to 6, characterized in that for determining the radius of curvature (Rg) of a grinding wheel of the grinding machine the positioning axis (C-C) of the bar cutting blade is tilted through the flank angle and the bar cutting blade is completely ground on the flanks and the top surface using a third calibrating grind.
8. The method according to claim 2 or 3, characterized in that for calibrating the grinding machine a further step involves the grinding of one of the two flanks of the bar cutting blade only with a roughing face of the grinding wheel whose position is to be determined
9. The method according to any one of claims 1 to 8, characterized in that the step of measuring the geometry of the calibrating blade involves the use of an absolute measuring device.
10. The method according to any one of claims 1 to 8, characterized in that the step of measuring the geometry of the calibrating blade involves the use of a comparative measuring device that compares the measured geometry of the calibrating blade with the dimensions of a calibrating gage.
11. The method according to any one of claims 1 to 7, characterized in that in the steps in which the bar cutting blade (10) is ground completely, grinding is performed under the same conditions under which bar cutting blades are sharpened on the grinding machine.

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