DE2200080A1 - FRICTION WHEEL DIAMETER MEASURING METHOD AND SWITCHING DEVICE FOR EXECUTING THE METHOD - Google Patents

Description

Friction wheel diameter measuring method and switching device for exercising of the method The invention relates to a friction wheel diameter measuring method according to which a measuring wheel known in its diameter against the surface of a rotating cylindrical work piece and pressed by static friction in one of the Peripheral speed of the workpiece offset corresponding to the rotational speed will. The revolutions and partial revolutions of the measuring wheel and the workpiece are converted into impulses and fed to an electronic evaluation logic, which consists of the number of counted pulses determines the diameter of the workpiece. Farther The invention relates to a switching device for performing the method So-called friction wheel diameter measuring devices are used to measure the diameter of cylindrical workpieces used. A friction wheel with an exact diameter, e.g. It is clamped against a .n a machine tool and revolving cylindrical The workpiece is pressed in such a way that the friction wheel is hit by the rotating workpiece is taken and thereby constantly rolling on the circumference of the workpiece. The measuring wheel is functionally linked to an angle encoder. The angle stepped consists of a pulse disk with a large number of radially extending slots, which faces a slit diaphragm in close proximity. Opposite a side surface the pulse disc, in front of the slit diaphragm, is a lighting device arranged, while a photo element is located behind the pulse disc. By the rotation of the measuring wheel also sets the pulse disk in rotation.

The photo element thus delivers a counting pulse with each angular step all a digital counter. As the diameter of the measuring wheel, the spacing he slots in the pulse disc, as well as the Number of decisive workpiece speed pulses are known, each counting pulse corresponds to a distance increment on the circumference of the Measuring wheel. The counting pulses are sent to an evaluation logic via an amplifier. The revolutions of the workpiece during the Measuring process and have an influencing effect in connection with a converter to the number of measuring wheel pulses to be added. The evaluation logic turns off the aforementioned components of the workpiece diameter are calculated and as a measurement result continuously displayed.

It is possible that the measurement result with such diameter measuring devices depends on the exact observance of the measuring wheel diameter, since the eßraddiameterdifferenen are directly proportional to the measurement result. Meanwhile, the measuring wheel is also defeated a certain amount of wear, so that the diameter decreases over time. The actual "diameter is therefore always a small amount from the" target "diameter differ. Even small dimensional deviations of the order of a few thousandths Millimeters inevitably lead to incorrect measurement results. The disadvantage becomes even more apparent because one - for the purpose of better resolution -the output from the pulse generator of the friction wheel during several revolutions of the workpiece Feeds impulses to the evaluation logic to determine the diameter. Add up those resulting from the difference between the "target" and "actual" values of the friction wheel Errors that go into the measurement result.

Furthermore, forms the use of a measuring wheel with a one-time preselected and thus also the predetermined nominal measuring wheel diameter is a considerable limitation for the possible uses and measuring accuracies of such a fuser. the Possible application i3t depending on the desired resolution3 accuracy under Consideration of the workpiece diameter to be measured, but also of the space available in the area of the measuring point of the workpiece.

The invention is based on the above disadvantages to fix or a friction wheel diameter measuring method and one to exercise the To create process-serving switching device, which the respective measurement conditions is adaptable. Based on a friction wheel diameter MeE method of the initially named type, the invention consists in that one of the evaluation logic during the The measuring process corresponds to the difference between the 'actual "and the" nominal "diameter of the measuring wheel and corresponding correction pulses depending on the workpiece diameter feeds.

These inventive, procedural measures are obtained always a very precise measurement result, regardless of whether the measuring wheel is the Corresponds to nominal dimension or not.

The prerequisite, however, is that after a certain operating time or the device must be calibrated when it is used again.

It is particularly advantageous if the diameter of the measuring wheel larger than the 'iSoll' diameter - in the present case synonymous with the nominal diameter - trains so that only positive correction pulses are fed to the evaluation logic. As a result, the circuit can be kept simple in its structure.

In the further embodiment of the invention, the nominal size is set of the measuring wheel diameter on the evaluation logic and reduces the workpiece speed pulses depending on the nominal dimension of the measuring wheel diameter.

This inventive procedure allows a flexible, but also a more rational use of the measuring device.

In particular, the use of the measuring device is now largely from Diameter of the workpiece to be measured independently, but with a high measurement accuracy is guaranteed.

The apparatus for practicing the method has according to the invention a correction pulse generator which is assigned to the evaluation logic, the correction pulse generator at least one correction tool and one correction scale for setting the difference between the "actual" and "target" dimensions of the MeBrad diameter.

As already described, it is advantageous to use an opposite The measuring wheel is slightly larger than the nominal diameter. This value, e.g. 0.03 mm, becomes set by means of the handle on the correction pulse generator. The correction pulse generator now supplies correction pulses during the measuring process, which correspond to the number pulses of the measuring wheel are paid. This compensates for the error or the Too large a measuring wheel, too small a counting rate to match the nominal diameter of the measuring wheel corresponding counting rate increased. A very precise measurement display is obtained in this way.

In the further embodiment of the invention, the evaluation logic has one side handle that is used to set the nominal diameter of the eating wheel, whereby this handle is connected to a frequency divider ('coaster) unit, the workpiece speed pulses according to the set and selected nominal diameter of the grinding wheel stocky.

The frequency divider (coaster) unit consists of elementary coaster components, e.g. 1: 2 or 1: 10 etc., depending on the selected measuring wheel nominal diameter be electrically connected. The frequency divider unit leads a downstream bistable multivibrator to a pulse, the pulse duration being a function of the selected and set Merad nominal diameter is. This will when replacing a measuring wheel, e.g. for a measuring wheel with a larger diameter, Disturbed relationship between the nominal diameter of the measuring wheel and that of the pulse disc delivered number of measuring wheel impulses as well as the speed impulses of the workpiece manufactured.

The invention is explained in more detail with the aid of the drawings.

In Figure 1, the evaluation logic is shown in the form of a block diagram. A measuring wheel 2, which via a shaft 5, loads against a rotating workpiece 1 a pulse disc 4 of a pulse generator 5 is connected. Here the pulse generator delivers 5 a signal sequence 7 corresponding to the measuring wheel speed to an amplifier with a pulse shaper 8, the output 9 of which is applied to an AND gate 10 with the pulse train 71. A that Machine part holding workpiece, e.g. a face plate 6 of a lathe carries a permanent magnet 11, which with each revolution of the faceplate on an Ilallelement 12 acts and thus registers the workpiece speed.

The signal 13 of the Hall element is applied to an amplifier and pulse shaper 14, the output 15 of which has a signal sequence 13 '. The latter signal is on the one hand at the NAND gate 28, and on the other hand at the frequency divider (coaster) unit 16 at. The NAND gate 28 here exercises the function of a "pulse selection"; it uses the first incoming workpiece speed pulse as the "start" pulse for the bistable multivibrator 17 connected to it via the output 32 and sets these. As a result of the setting process, the RAND gate is activated via output 18 28 through the feedback 18 'blocked and on the other hand at the same time the applied AND gate for the already mentioned measuring radium pulses 7 'activated. The period, with which this AND gate 10 is permeable, is through the frequency divider (divider) unit 15 determined.

The first to arrive and to set the bistable multivibrator 17th as well as the following impulses are fed directly to this unit, namely up to In terms of time, the n-th pulse arrives. This nth pulse causes the Output 17 'sends a "stop" pulse to flip-flop 17, which in turn uses the output 18 the AND gate 10 blocks again. The reducer stage 16 is designed in such a way that that via the setting handle 16 'the reduction ratio 1: N accordingly the selected measuring wheel nominal diameter can be varied and thus differing Periods of time until the "stop" pulse is sent to the bistable multivibrator 17 and so that 10 can be given to the AND gate. With this action the relationship becomes between the nominal measuring wheel diameter and the influence of the workpiece speed at constant Number of slots restored.

The following are used to explain the function of the device in more detail Treatises: It is well known that the nrehzailen of two cylindrical ones rolling on one another are Bodies inversely proportional to their diameters.

If n1 is the measuring wheel speed, a is the number of slots in the pulse disk 4, n2 is the workpiece speed, dl is the nominal measuring wheel diameter and d2 is the workpiece diameter If one forms this relation according to n1 m, one obtains: Furthermore, if n1 'is the measuring wheel speed difference due to a measuring wheel that deviates from the nominal dimension, and also dl / the difference between the actual dimension and the nominal dimension of the measuring wheel, the following relationship can be derived: It then follows from (2) and (3) With this equation, the quantities to be compensated by the x-correction unit and the frequency divider (scaler) unit can be shown immediately, namely that a) iii is equivalent to the number of correction pulses and this number is a function of and d2 is.

b) It can also be seen from equation (4) that the highlighted The second quotient of the product consists of setting variables or device constants.

With a variable design of the nominal diameter of the wet wheel and with a constant one number of slots in the pulse disk is the influence of the workpiece speed can only be corrected by varying the reduction ratio.

According to equation (2), di and a are constants for carrying out the measurement Sizes, while n1 and n2 with the means provided for the determination of the Workpiece diameter can be registered.

A permanent magnet is attached to a guide rod 2 'holding the measuring wheel 2 22 attached, when moving the measuring head against the workpiece, during a Hubes of e.g.

2 mm, strokes over the field plate 21 and generates a pulse s.

This signal automatically resets the evaluation logic at the beginning of the measurement. The pulse is passed through an amplifier 23, its Output to a timer 24 is present. The signal of the time stage blocks a possible one Counting process until the acceleration phase of the measuring wheel has ended. Preferably this time stage, designed as a monoflop, is set to a time of one second. To prevent incorrect measurements from being recorded, e.g. by rolling over a Snane or the like. Is at the guide rod end 2 'a, with a small mass provided, pressure-sensitive transistor 29 arranged, which at an acceleration of the measuring head, which is slidably mounted in the guide line, triggers an impulse and through an amplifier 30 supplies a pulse to the timer 24. The output 25 of the timer blocks on the one hand by means of a monostable multivibrator 26 a NAND gate 28, as well as the frequency divider (divider) unit 16 and on the other hand to one - to be explained in more detail below - adding unit 27. With this Pulse, the counting unit is also set to a defined state. The exit 31 of the monostable multivibrator 25 lies together with the output 15 of the amplifier 14 and the output 18 of the flip-flop 17 at the NAND gate 28, whose inverted Output 32 - as already mentioned - sets the bistable multivibrator 17 accordingly. As long as there is a signal from the timer 24, the flip-flop 17 blocks with its output 18 the AND gate 10, so that at the output '19 of the AND gate 10 no measuring wheel pulses are issued. The output 19 of the AND gate 10 is above the adding unit 27 to a decade counter 20, the outputs 46 'of which are connected to a decoder 33 stand. The decoder is provided with a diameter indicating display 34, consisting of digit display tubes 34 'connected. With the decade counter 20 a comparison circuit 35 is connected, the two tolerance preselection switches 36 and 37, the preselection switch 36 for setting an upper and the preselection switch 37 is used to set a lower tolerance limit. Exceed the values output by the decade counter the upper or lower tolerance limit, see above if the comparison circuit 35 triggers a pulse to a shutdown logic 38, which e.g. makes a machine contactor 39 respond. Through the machine contactor an operation is ended, e.g. a tool disengaged from the workpiece brought. The essential element of the evaluation logic is that shown in dashed lines Correction unit 40 shown in the field. This correction unit consists of one Correction pulse generator 43 with two correction handles 41 and 92, one monostable Flip-flop 45 and an adding unit 27.

The pulse frequency F emitted by the correct pulse generator 43 can be controlled by means of the correction handle 42 according to the deviations of the "actual dimension" from the nominal dimension des Merades in the order of 10 5 and by means of the correction handle 41 in of the order of 10-2 mm.

The frequency F, taking into account possible fluctuations due to thermal influences, is many times higher than the correction frequency that is later supplied to the decade counter and required. The correction pulse generator has a basic frequency F1. The frequency F output by the correction pulse generator shows the following relationship: This frequency is available at output 4-4 of the correction pulse generator.

The other variable to be taken into account by the workpiece diameter d2 according to point a is effected by a monostable flip-flop 45 which is connected to the decade counter 20 with a line 46 at the connection 46 '. The transmission to the next whole millimeter on the numeric display tubes is initiated via line 46. In each such transmission process, the monostable multivibrator emits its pulse for a fixed predetermined period of time t> of, for example, 0.8 ms. The output pulse A of this monostable multivibrator obeys the relationship: and is matched to the basic frequency F1 of the correction pulse generator 43. The components A and F of both outputs 47 and 44 are fed to an AND gate 48, with the opening of the monostable multivibrator 45 the pulses from the correction pulse generator being passed through the AND gate and fed from there to the adder 27. The frequency A1 at the output of the AND gate 48 follows the Be relationship: As can be seen from this equation, all parameters influencing the measurement result that arise from a deviation from the nominal diameter of the measuring wheel are recorded.

The function of the adder is explained in more detail below. Correction pulses and the measuring wheel pulses are now added via a line 45 ' given to the input 20 'of the decade counter 20.

A block diagram of the correction unit is shown in FIG. The output 51 of the AND gate 48 is connected to a pulse divider 52, which is connected to a monostable flip-flop 53 is in connection. Through the pulse scaler the actual number of correction pulses is output while the monostable multivibrator forms these pulses with a comparatively small width of, for example, 5 / μs, which are then fed to an adder 54. The adding stage is controlled by the Line 19 supplied the measuring wheel pulses.

The adder prevents a coincidence between measuring wheel pulses and correction pulses. The output 45 'of the.

The adder stage leads via a line 45 'to the input 20' of the Dekadenzäblere and thus to the digit display tubes 34.

In the pulse diagram of FIG. 3, the measuring wheel pulses are on the belt 58 7, which are applied to the adder 54 (FIG. 2). The band 59 shows the Correction pulses 56 delivered by the correction pulse generator. as tape 60 shows - that a relatively narrow correction pulse 56 'with a measuring wheel pulse 7 'coincides, a logic element (EXCLUSIVE-OR) is used in the adding stage, the pulse 7 'split into two pulses 57 and 57'; so there are two counting pulses. If, on the other hand, a correction pulse 56 falls into a pulse gap 58 of the measuring wheel pulse train, 80 no splitting is carried out, but the correction pulse based on the logical Element passed to the decade counter unchanged.

8 claims 3 figures

Claims (8)

P a t e n t a n s p r ü c h e 1. Friction wheel diameter measuring method, after which a measuring wheel known in its diameter against the surface of a rotating one cylindrical workpiece pressed and by static friction in one of the peripheral speed of the workpiece corresponding speed of rotation is offset and where one converts the revolutions and partial revolutions of the measuring wheel into pulses and one electronic evaluation logic, which is based on the number of pulses counted The diameter of the workpiece is determined, which means that it is not possible to one of the evaluation logic during the measuring process according to the. Difference between "Actual" and "nominal" diameter of the measuring wheel and depending on the workpiece diameter supplies corresponding correction pulses. 2. friction wheel diameter measuring method according to claim 1, characterized g e k e n n z e i c h n e t 7 that the nominal dimension of the measuring wheel diameter (d1) can be measured on the Evaluation logic sets and the workpiece speed pulses (13,13 ') as a function from the nominal dimension of the measuring wheel diameter, variably scaled down. 3. Switching device for performing the method, thereby g e k e n n z e i c -h n e t that they have a correction pulse generator assigned to the evaluation logic (43) which has at least one correction handle (41 or 42) for setting the difference between the "actual" and target dimensions of the measuring wheel diameter. 45 switching device according to claim 3, characterized in that there are g e k e n n -z e r c h n e t that they have another handle (16 ') for setting the nominal diameter of the measuring wheel (d1), the handle with a sequence divider (coaster) unit (16) is in connection, which the workpiece Speed impulses (13 ') geared down according to the set and selected Mcßrad nominal diameter. 5. Switching device according to claim 3, characterized in that g e k e n nz e i c h n e t that the correction pulse generator (43) represented by an astable trigger stage cooperates with a monostable multivibrator (45), the counter pulses from one Decade counter (20) are fed to the evaluation logic, the output (44) of the correction pulse generator together with the output (47) of the monostable multivibrator an AND gate (48), the output of which is connected to a coaster uncl one, one Coincidence of the counter pulses with the adding unit preventing the correction pulses (27) is connected. 6. Switching device according to claims 3 and 5, characterized g e -k e n n z e i c h n e t that the adding unit (27) has a coaster (52) and a flip-flop (53) and an adder (54), the AND gate (48), the scaler (52) applied correction pulses in the reducer to the real correction pulse number reduced and converted into pulses with a narrow pulse width in the monostable multivibrator as well as are added to the measuring wheel pulses in the adding stage, in such a way that that when a correction pulse (56 ') coincides with a measuring wheel pulse (13') the latter is split so that two desired pulses (57 and 57 ') arise. 7. Switching device according to claims 3 and 4, characterized g e k e n n z e i c h n e t that the output of the workpiece speed pulse amplifier (14) over a NAND gate (28) with the input of the frequency divider (reduction) unit (16) is connected, the output of which sets a bistable multivibrator (17), and thus on an AND gate (10) acts. 8. Switching device according to claims 3 and 5 to 7, characterized g e k E n n z e i c h n e t that the output (45 ') of the adder (27) at the counting pulse input (20 ') of the decade counter of the counter circuit (34).