DE2159876A1 - Grinding machine with adjustment control system - Google Patents

Description

Dr. F. Zumsteln sen. - Dr. E-Ässmann Dr. R. Koenlgsberger - Dlpl.-Phys. R. Holzbauer - Dr. F. Zumsteln jun.

PATENT LAWYERS

TELEPHONE: COLLECTIVE NO. 22 5341

TELEX C29979

TELEGRAMS: ZUMPAT CHECK ACCOUNT: MUNICH 91139

BANK ACCOUNT: BANK H.AUFHÄUSER

8 MUNICH 2.

BRÄUHAUSSTRASSE 4/111

4 / Ma
TF-369-G

TOYODA KOKI KABUSHIKI KAISHA, Kariya-shi, Aichi ~ ken s = = = = s rs = = s = r ss s = s = = = = s = β = s: = = = rssss = = ss = s = r S ss = = as s = es = s = t = ss =: s

Grinding machine with adjustment control system

The invention relates to a grinding machine with an adjustment control system, in which the feed speed of the grinding wheel is controlled in such a way that the grinding resistance, which is exerted on the grinding wheel, stands for itself continuously changing grinding conditions.

In a known grinding machine with an adjustment control system, the feed speed of the grinding wheel is controlled in such a way that da0 the shift resistance at a desired optimal value can be held. Such a grinding machine has proven to be very effective in terms of effectiveness improve the grinding process, but it has been shown that that it cannot provide products of excellent quality. ”It was therefore desirable to have an improved adjustment control system to develop which products of the same

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consistently cheaper high quality and higher grinding efficiency «" *

The aim of the invention is therefore a grinding machine with a such improved accommodation control system. This system aims to produce products of consistently affordable high quality and can deliver a high level of economy of grinding. This system is also intended to reduce the drag resistance that is applied to the Grinding wheel is exercised towards an objective value decrease according to the port steps of the grinding process. The system is also intended to cause the dressing device A dress the grinding wheel when the volume of material

that has been removed by the grinding process, a predetermined Value becomes equal

This is done in a known grinding machine with a bed, a grinding wheel block which is slidably mounted on this bed and is provided with a rotatable grinding wheel, a table which is slidably mounted on this bed to carry a workpiece, a drive device for the grinding wheel block or move the table to 'ura the grinding ': - carry out an operation on the workpiece, a resistance determination device in order to determine the grinding resistance exerted on the grinding wheel and to generate an output signal proportional to this grinding resistance,

and a control device to process the necessary information obtained, achieved by according to the invention an extent determining means to obtain an output signal to produce that is proportional to the extent of the grinding process is, through a first operational circuit, to establish a running optimal drag resistance on the basis of the "ofojective / Calculate grinding resistance, which is determined by the control device and the output signal of the extent determining device is given, where the running optimal drag resistance is reduced to this "objective * grinding resistance, when the output of the extent determining means increases and by a feed control means, ura die

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To operate the drive device in such a way that the drag resistance, that is exerted on the grinding wheel, same as this ongoing optimal grinding resistance is maintained.

In the following, the invention is explained in more detail using an exemplary embodiment with reference to the accompanying drawings explained.

Fig. 1 graphically shows the relationship between the volume of material removed and the unit resistance.

Fig. 2 shows in block diagram a control system which is used in a grinding machine according to the invention.

3 shows a block diagram of an adaptation control system according to the invention.

Figure 4 shows how the amount of grinding wheel wear is measured.

Fig. 5 is a block diagram showing the operational circuit for calculating the current optimal unit resistance.

Fig. 6 shows in section a size measuring device _o

Before the preferred embodiment of the invention is described, the context should be explained with reference to FIG between the volume of material removed and the grinding resistance .per unit of width, which is here as Unit resistance is called. The line ZL shows that the limit of the total volume of material that passes through a grinding process from the start of grinding immediately after dressing the grinding wheel until Burn or grinding points on the sanded surface can be removed, changes according to the changes in the unit resistance. The line ZHs shows the relationship between the unit resistance and the total volume of the material starting after a

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Dressing the grinding wheel under the condition removed can be that the roughness of the sanded surface is kept within a desired degree Hs. The lines ZHr and ZHt show the same relationships as that Line ZHs at different degrees Hr and Ht of surface roughness. To the workpiece with high effectiveness and low To grind cost, it is necessary to unity resistance and to increase the total volume of material removed. Like Pig. I shows but takes the total volume of the removed material when the unit resistance increases.

With these facts in mind, the feed speed of the grinding wheel must be controlled so that the unit ^{resistance can be kept at the "ob j ek ti ven ';} unit resistance fs, which corresponds to the point of intersection P of the lines ZL and ZHs. Keeping the unit resistance constant Standes, however, has the disadvantage that a product of excellent quality cannot be obtained, that is, the roughness of the ground surface is kept within a degree Hr better than the desired degree Hs until the volume of material removed reaches Zl. This causes unnecessary work and is undesirable from the standpoint of the effectiveness of grinding.

In the case of the grinding machine according to the invention, the binary resistance becomes in a first grinding process immediately after dressing the grinding wheel to an initial unit resistance set fo, the greater than the objective

is
Unit resistance fs, where the roughness of the ground surface is kept within the desired degree Hs. The unit resistance is then reduced to the objective unit resistance fs in accordance with the progress of the grinding process.

2 0 9 8 2 3 / 0b 6 5

The invention will now be explained in more detail with reference to the other figures, FIG. 2 in particular showing a bed 40 on which a table 5 is slidably mounted. A pulse motor 5b is fixed to the bed 40, and rotates a feed locker el, with a threaded engagement with the table 5 in xst _t so that the table 5 can be moved on the bed 40th The table 5 carries a headstock 7 and a tailstock. A work spindle, not shown, is rotatably supported by the headstock 7 and is driven by a hydraulic motor 7b. A workpiece W is held between the tips of the headstock 7 and the tailstock, and the rotation of the work spindle is transmitted thereto through a drive dog. The rotational frequency of the hydraulic motor 7b is controlled by a conventional electro-hydraulic servo valve 7a. A size measuring device 9 which measures the diameter of the workpiece W is slidably mounted on the table 5 and can be moved towards and away from the workpiece W by a hydraulic cylinder, not shown. The size measuring device 9 comprises two feelers 41a and 41b and an electrical measuring device for measuring the distance between the feelers. A counter 46, which is connected to the size measuring device 9, represents the workpiece diameter in digital counting, since the workpiece diameter is measured by the size measuring device 9, converted into this from the analog value to the digital value and then sent to the counter 46. The details of the size measuring device will be described later

A grinding wheel 42 is attached to a spindle, which rotatably held by a grinding wheel stock 6 through a hydraulic bearing which is fixedly attached to this is. The grinding wheel 42 is provided with one not shown Motor connected, which on the grinding wheel block 6 is attached and the grinding wheel 42 rotates. A sliding

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Base 43 is attached to the bed 40 and can be in a

Slide in the direction perpendicular to your table 5 The grinding

seheibenstocfc 6 is in turn slidably attached to the sliding base 43 parallel to the latter. A pulse motor 6b is attached to the slide block 43 and rotates a feed screw 44 which is threadedly engaged with the grinding wheel stock 6 so that the grinding wheel stock can be moved towards and away from the workpiece W. ^E ine known dresser for dressing the grinding wheel 8 42 is attached to the grinding wheel Stock. 6 A grinding wheel compensation device 12 is attached to the bed 40 and rotates a compensation spindle 45 which is in engagement with the slide base 43 so that the slide base 43 can be moved towards the workpiece W ". The operation of the grinding wheel compensating means will not be discussed in detail, since such apparatus is known for the skilled man, and this is sufficient to indicate _s that the grinding wheel compensation device 12 the slide base 43 by an amount on the workpiece W to bewegtj equal to that of the dressing on the grinding wheel 42 is *

The pulse motors 5b and 6b are each provided with pulse motor drive circuits 5a and 6a, which in turn respond to a conventional numerical control device 2. To this Way, the respective movable components are moved according to the information on a not shown Tape are stored and read by a tape reader 1 and sent to the numerical control device 2 are transmitted. Since the tape reading device 1 and the numerical control device 2 are known and e.g. numerical control system manufactured by Fujitsu Ltd., Kawasaki, Japan and identified as FANUC MODEL 260 im Trade is supposed to be. can only be described briefly here.

A pressure differentiator 10 is provided and is responsive to the pressure differential created by the drag resistance (F) is generated on the grinding wheel 42 between the

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front and rear pressure chamber of the hydraulic Camp is exercised. The pressure differentiator 10 is known and can be of the type which converts the pressure differential into a converts electrical signal. The output signal of the pressure differentiator 10 is applied to an adaptation control system 3 which will be described later

With 47 a preselection device is referred to, in which the Distance between the axis of the workpiece W and the front surface of the grinding wheel 42 that is in its retracted Position is brought into positionj is preselected in digital counting. A conventional contactless microswitch 11, which is attached to the sliding base 43, generates an electrical signal, to open a gate circuit 48 when the grinding wheel block 6 moves into the retracted position · The Value or number selected in preselector 47 is, is passed to a counter 49 and registered in this according to the electrical signal. The counter 49 connected to the numerical control system 2 and the adjustment control system 3 subtracts the number of electrical pulses supplied to the pulse motor 6b of the value or number registered in it or is stored, thus showing the current distance L between the grinding surface of the grinding wheel 42 and the Axis of the workpiece W.

Fig. 3 shows the adjustment control system 3 in which one revolution s control device 20 with the numerical control system 2 and the counter 46 connected to the size measuring device 9. The rotation control device 20 calculates the rotation frequency η of the work spindle according to the following equation:

η = Vs / Itdo,

where Vs is the desired peripheral speed of the workpiece W is determined by the numerical control system 2

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and do is the workpiece diameter measured by the size measuring device 9. The calculated Rotation frequency η is given to a digital-to-analog converter 21 and is converted into the corresponding voltage in this converted. The output voltage of the digital-to-analog converter 21 is amplified by a conventional amplifier 22. The electro-hydraulic servo valve 7a controls the flow rate of the pressure fluid supplied to the hydraulic motor 7b according to the output voltage of the booster 22 so as to increase the frequency of rotation η of the hydraulic Motor 7b to regulate.

A division circuit 19 connected to the counter 46 calculates half do / 2 of the workpiece diameter. A comparison circuit 23 connected to the division circuit and the counter 49 compares the half diameter do / 2 with the current distance L between the grinding surface of the grinding wheel & 2 and the axis of the workpiece W and produces an output when the current distance L is equal to or becomes smaller than half the diameter do / 2. A comparison circuit 24, which is connected to the counter 46 and the numerical control system 2, compares the workpiece diameter do with the diameter df of the finished workpiece given by the numerical control system 2 and generates an output signal when both become equal. A NOT circuit 25 connected to the output terminal of the comparison circuit 24 reverses the output of the comparison circuit 24. An AND circuit 26 connected to the output terminals of the division circuit 19, the comparison circuit 23 and the NOT circuit 25 enables the output signal of the division circuit 19, which represents half the diameter do / 2, to be transmitted to a subtraction circuit 28 when the comparison circuit 23 and the NOT circuit 25 generate output signals. An AND circuit 27 connected to the output terminals of the counter 49, the comparison circuit 23 and the NOT circuit 25 enables the output signal

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of the counter 49, which represents the current distance L, is transmitted to the subtraction circuit 28. The subtraction circuit 28 subtracts the running distance L from half the diameter do / 2.

Half the diameter do / 2 and the running distance .L become the same when the grinding wheel 42 is immediately after the dressing process comes into contact with workpiece W. » However, when the grinding wheel 42 is worn, it becomes half that Diameter do / 2 greater than the running distance L when the grinding wheel 42 comes into contact with the Werksftbk W, such as Fig. 4 shows.

It is clear that the difference between half the diameter do / 2 and the running distance L coincides with the amount (f of wear of the grinding wheel 42. Since it is known experimentally that the amount of wear of the grinding wheel is almost proportional to the volume of the removed In the embodiment of the invention, the unit resistance is reduced in accordance with the increase in wear of the grinding wheel.

A counter 29, which is connected to the subtraction circuit 28, registers the extent ei of the grinding wheel wear. The counter 29 is reset by the output of the comparison circuit 24 every time a grinding operation is over. Denoted at 30 is an operation circuit for calculating a running optimum unit resistance fv according to the following equation au

■ C.r

fV

ι + κ << Γ -. <α)

where fs is the objective unit resistance, c ^ the extent of the Grinding wheel wear, c / Ί the maximum amount of grinding disk wear and K is an appropriate positive constant. As shown in Fig. 5, the operation circuit includes 30 a subtraction circuit 51, a 'multiplication circuit 52, an addition circuit 53 and a division

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circuit 54. The subtraction circuit 51 is connected to the counter 29 and a preselection circuit 50, in which the maximum extent cfl of the grinding wheel wear and the suitable positive constant K are preselected as digital values. The subtraction circuit 51 subtracts the maximum amount cfl of grinding wheel wear from the amount of grinding wheel wear. The multiplication circuit 52 is connected to the subtraction circuit 51 and the preselection circuit 50 and multiplies the difference Q- (fl with the constant K. The addition circuit 53 adds 1 to the output K (cf- <fl) of the multiplication circuit 52. The division circuit 54 divides the objective unit resistance fs given by the numerical control system 2 by the output l + K (cT- (fl) of the addition circuit · 53. Since the If the current optimum unit resistance fv ^{! is determined} as described above, it is changed from the initial unit resistance fo (= fs / (lK * <fl)) to the objective unit resistance fs as the amount cT of grinding wheel wear increases objective unit resistance fs is changed in accordance with the change in the quality of the workpiece material.

The output signal fv of the operational circuit 30 is fed to a digital-to-analog converter 31, where it is converted into the corresponding voltage, which is fed to the connection of a differential input amplifier 32. A digital-to-analog converter 34 receives the information about the width b of the part to be ground by the numerical control system 2 and converts the digital information - ± n the electrical voltage corresponding to the width b. A division circuit is denoted by, the output signal of the pressure differentiator 10, which represents the shift resistance P, divided by the output signal of the digital-Äna ™ log converter 34, which represents the width b, so as to give a real unit resistance F / ta calculateα The

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real unit resistance F / b is assigned to the other terminal of the Differential input amplifier 32 out and compared in this with the current 0ptimal unit resistance fv. Of the Differential input amplifier 32 produces an output voltage corresponding to fv + (fv-F / b). The output voltage fv + (fv-F / b) is fed to a pulse generator 35 which generates pulses whose frequency is proportional to the output voltage fv + (fv-F / b). The pulses are supplied to the pulse motor 6b via the pulse motor drive circuit 6a. Of the The grinding wheel block 6 is therefore moved towards the workpiece W, where the feed speed of the grinding wheel is controlled so that the real unit resistance F / b is kept equal to the current optimum unit resistance fv will.

Denoted at 36 is an operation circuit for determining the volume of the removed material Z according to the following equation to calculate;

Z = 5tb «[(Do / 2) ² - (df / 2) ² ,]

where b is the width of the part to be ground, Do is the workpiece diameter before the grinding process and df is the diameter of the finished workpiece is given by the numerical control system 2. The calculation is performed when a signal is supplied to the operation circuit 36 indicating the engagement of the sensors 41a and 41b of the size measuring device 9 with the circumference of the workpiece W. As the entire volume of material removed corresponding to the intersection point P, as shown in Fig. 1, changes when the quality of the work tu ckmateriaüTs changed the calculated volume Z of the removed material must be converted into the volume of the standard material * For this conversion, a multiplication circuit 55 multiplies the calculated volume Z of the material removed with a coefficient Kw determined by the numerical control system 2 is given, according to the quality of the work

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Piece of material that is ground. The converted volume of the removed material is successively accumulated by an accumulator 37. The accumulated volume έ.ζ of the removed material is fed to a comparison circuit 38. The comparison circuit 38 generates an output signal which causes the dressing device 8 to increase the extent of the. Grinding wheel 42 trues when the total volume £ Z is equal to the standard volume Zl. The accumulator 37 is reset by the output signal of the comparison circuit 38.

As shown in Fig. 6, the size measuring device 9 comprises a Bracket 57, which is attached to the guide rod 58, which is slidably attached to the table 5, and to a piston rod 59 of the hydraulic cylinder is attached. A block 60 is slidably attached to a guide 61 which is upright attached to the bracket 57, i.e. a cylinder 62 bored in the block 60, the guide 61 slidably receives it on. There is a guide pin 63 attached to the guide 61 is slidably engaged with a longitudinal slot 64 formed on the block 60, the rotation of the block 60 is obstructed and the range of axial movement of the block 60 is determined. A rod 65 extends through a hole 66 penetrating the block 60 in a direction parallel to the cylinder 62 and is slidable received in two sockets 67 and 68 which are fastened in the hole 66. The rotation of the rod 65 is controlled by the Prevents engagement of a pin 69 attached to the block 60 with an elongated keyway 70 formed on the Rod 65 is formed. Two feelers 41a and 41b are on the front surface of the block 60 and on the lower end, respectively the rod 65 attached.

A holder 71, which is attached to the upper end of the rod 65, carries a magnetic scale 72 which is in a Direction parallel to the rod 65 extends. A reading head 73 is attached to the block 60 so that the reading head 73 is coaxial

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with the magnetic scale 72. The magnetic scale 72

and the reading head 73 are therefore displaceable with respect to one another in accordance with the relative displacement of the feelers 41a and 41b. Since the magnetic scale 72 and the reading head 73 are known and e.g. as »SONY PRECISION MAGNETIC SCALING SYSTEM "are distributed by the SONY company in Japan, they should only be described briefly here.

The reading head 73 generates an output signal every time when it detects a unit length that is determined by a periodically changing reference magnetization on the magnetic Scale 72 is shown and can distinguish the direction of movement of the feelers. As shown in Fig. 2, the output signals generated by the reading head 73 are fed to the counter 46. It is clear that the number of Output signals from the value or number that is in the counter 46 is stored, is subtracted when the sensors 41a and 41b approach each other, and that the number of output signals is added to the value of the counter 46 when the sensors move away from each other, so that the counter 46 is continuous indicates the distance between the sensors 41a and 41b.

The rod 65 is connected to a weight 74 via a flexible part 75, which via two pulleys 76 and 77 which are rotatably attached to a housing 78 which is attached to the bracket 57. The weight 74 is sliding in Engaging a cylinder 79 bored into the housing 78. There is a guide pin .80 attached to the weight 74 is slidably engaged with a longitudinal slide 81 formed on the cylinder 79, the rotation becomes of the weight 74 is prevented and the range of axial movement of the weight 74 is fixed. Because the weight 74 is heavier when the rod 65, etc., the lower feeler 41b is forcibly moved upward. The upper sensor 41a will be through Weight forcibly moved downwards. If one by a solenoid actuated valve 82 shifted to the other state

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compressed air is supplied to the cylinders 62 and 79 and. the feelers 41a and 41b move away from each other. If against it the solenoid operated valve 8 2 is pushed into the state shown in Fig. 6, the cylinders 62 and 79 are connected to the atmosphere and the feelers 41a and 41b therefore approach each other to come into contact with the circumference of the workpiece W. "The signal that the engagement of the feelers 41a and 41b with the circumference - des Workpiece-W is represented by a conventional one, not shown Timing is generated which is turned on when the solenoid operated valve 82 in those shown in FIG State is shifted, and which generates the signal after a predetermined duration.

The grinding machine with the adjustment control system described above operates in the following manner. It is assumed, that the dressing device 8 has just dressed the circumference of the grinding wheel 42, then the grinding wheel wear just fixed. After the workpiece W between the Headstock 7 and the tailstock is supported, a start button (not shown) is pressed · The size measuring device 9 is moved against the workpiece W and then the solenoid operated valve 82 is in the state shown in FIG postponed. As a result, the feelers come into contact with the circumference of the workpiece W and measure the workpiece diameter do. The operation circuit 36 calculates the volume Z of the removed material and the multiplication circuit 55 multiplies it the calculated volume Z with the coefficient Kw to obtain the converted volume and the accumulator 38 adds up the converted volume. The workpiece W is rotated by the hydraulic motor 7b at the rotation frequency η determined by the rotation controller 20 is calculated.

Then the grinding wheel stock 6 is on the workpiece W with

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is advanced at a high speed in accordance with the feed pulses supplied to the pulse motor 6b by the numerical control system 2. When the current distance L between the grinding surface of the grinding wheel 42 and the axis of the workpiece W becomes equal to half the diameter do / 2, the comparison circuit 23 generates the output signal. The numerical control system 2 stops supplying the feed pulses to the pulse motor 6b in accordance with the output of the comparison circuit 23. Since the pulse motor 6b continues to be supplied with the pulses which start to be generated by the pulse generator 35 after the output of the comparison circuit 23 is generated, the grinding wheel 42 then moves in the forward direction and begins to grind the workpiece W with the real unit resistance F / b being kept equal to the current optimum unit resistance fv. When the diameter do of the workpiece W is equal to the diameter df of the finished workpiece, the comparison circuit 24 generates an output signal. The numerical control system 2 causes the pulse generator 35 generating pulses terminated according to the output signal of the comparator 24 _O then provides the numerical control system 2 pulses to the pulse motor drive circuit 6a, to rotate the pulse motor 6b in the opposite direction, and the grinding wheel Stock is characterized in moved to the retracted position. The ground workpiece is then removed from the grinding machine and one grinding cycle is completed.

The same grinding cycles are repeated until the comparison circuit 38 produces the output when the summed up Volume £ z becomes equal to the standard total volume Zl of the material removed. The dressing device 8 aligns the grinding wheel 42 from and the accumulator 37 is reset according to the output signal of the comparison circuit 38. The real unit resistance F / b is naturally decreased

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corresponding to the increase in the extent / of the grinding wheel wear in the successive grinding processes. Of course, the real unit resistance can be reduced will correspond to the increase in the accumulated volume of material removed.

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Claims (1)

Claims fl.J grinding machine with a bed, a grinding wheel block, which is slidably mounted on the bed and fitted with a rotating grinding wheel, a table which slidably mounted on this bed to carry a workpiece, a drive device to either to move the grinding wheel block or the table, to perform a grinding operation on the workpiece, a resistance determining device to the Determine grinding resistance acting on the grinding wheel is applied, and to produce an output signal proportional to that drag resistance, and one Control device to provide the required information, characterized by a Extent determining means (28) for producing an output signal proportional to the extent of the grinding operation isti by a first operational circuit (30) to a running optimal grinding resistance due an objective drag resistance that is generated by the Control device (2) is given, and the output signal from the extent determining device (28) Calculate this running optimal grinding resistance toward the objective grinding resistance is decreased in accordance with the increase in the output of this dimension determining means (28), and by a feed control device (32, 35) to the drive device (6b) to be operated so that the drag resistance that is on the grinding wheel (42) is exercised, this ongoing optimal grinding resistance is kept the same. 2, grinding machine according to claim 1, characterized in that a size measuring device (9) for continuous 209826/0565 - J. ö - normal measurement of the workpiece diameter, a second operation circuit (20) for calculating the rotational frequency of the workpiece (W) due to the desired peripheral speed of the workpiece, which is determined by the control device (2) is given, and the workpiece diameter measured by the size measuring device (9), and a drive device (7a, 7b) is provided to move the workpiece. (W) to rotate according to the rotation frequency which is calculated by this second operation circuit (20) will. 3. Grinding machine according to claim 1, characterized in that that a size measuring device (9) for continuously measuring the workpiece diameter, a dressing device device (8) for dressing the circumference of the grinding wheel (42), a third operation circuit (36) for calculating the volume of material removed due to the workpiece diameter measured by this size measuring device (9) the diameter is measured before the grinding process of the finished workpiece and the width of the to grinding part, which is given by the control device (2), an accumulator Ö7) to the volume of the removed To add up material, and a comparison circuit (38) for generating a signal are provided, this causes the dressing device (8) to remove the grinding wheel (42) trains when the accumulated volume that is stored in this accumulator (37) is the same becomes the standard total volume. , 4. Grinding machine according to claim 1, characterized in that that the extent determining device (28) is a position indicating device (49) to the current distance between the grinding surface of the grinding wheel and the Display the axis of the workpiece, a size measuring device (9) for continuously measuring the workpiece diameter, 209828/056 5 ■ - 19 - a division circuit (19) for calculating half the workpiece diameter, and a wear measuring device (28) for calculating the difference between this running distance and half the workpiece diameter in order to measure the extent of the grinding wheel wear. 9828/0565