DE2438641C3 - Method and arrangement for testing individual gear teeth - Google Patents

Description

3 ₄

^L - According to the invention, this object is thereby achieved. However, the transducer 6 could also be used

solves that the impact energy is applied to the tooth by facing the flank 4.
. After the thyristor 8 is switched on, a surge in flow through a previously charged capacitor 9 (with the capacitor coil) is generated _{by a} discharge current _{surge through the} Exciter further developments of the invention provide coil 5 (with the inductance L _E ) . With regard to J that 'the shock-like excitation periodically repeats the excitation of the magnetic field that is through - \ _wild and that the repetition frequency of the shock-like field line 10 is indicated, the discharge , ') excitations are the same size as the mains frequency or current surge effective as a flow surge. In the case of An-V. Multiplication or division by a whole io would result in constant relative permeability' number obtained from this in _the air gap between the flank 4 and the coil r arrangements for implementing the inventive core 11 (the conclusion was not drawn); _ the method provide that to produce the magnetic forces of attraction, which increase with the square * ■ of a previously charged condensation.

capacitor discharges through the excitation coil that the 15 The losses "of excitation coil 5 and capacitor

The excitation coil on the secondary winding of a Trans- tor 9 is so small that if there is no Thy-

formator is connected, through which the primary transistor 8 the time-varying discharge current

winding a previously charged capacitor would disappear after a decay process,

that discharges the natural frequency of the resonant circuit taking it several times at intervals of approximately each

from the capacitance of the capacitor and the induction ao of a half cycle of the natural oscillation with the other

Activity of the excitation coil is approximately the same as the approaching natural frequency
the natural bending frequency of the tooth or greater than

this is and that the discharge of the capacitor f _E = Ij (In VLe ^ Ce)
is initiated by a control pulse, the one

arranged in the discharge circuit thyristor from 25 changes its direction. The thyristor 8 can, however, put the blocking into the conductive state. only current in one direction through, in the other The advantages achieved with the invention exist direction it blocks. Therefore, only in the first half-cycle, in particular, a discharge current surge occurs due to the Erre material faults, small hardening cracks at the tooth root and gerspule 5, so that the duration of the discharge beginning cracks due to material fatigue at 30 current impulses and the shock of the magnetic Andes Flanks are revealed early on that the accuracy frequency f _E changes by drawing forces indirectly proportional to the own systematic objective test, since the thyristor 8 is initially not switched on again when dimensioning highly stressed tooth. Through a suitable choice of wheels increases and the safety margin decreases L _n and C ,. _: the shock duration can be short enough that in most cases the gear will hold at 35. Additional adjustment possibilities do not need to be expanded, that the device is portable through the interposition of a transformer, that the energy consumption creates a test.

Supply from a portable accumulator enables the surge of magnetic attraction forces

light and that the peak value in the first half a deflection of the

period of the free flexural oscillation of the tooth near tooth 1 and therefore means a transmission

is too independent of its damping and the impact energy on tooth 1. Once the

Sensitivity, therefore, without readjustment or regulation, leads to tooth 1 that is bumped and then left to its own devices,

remains approximately constant. if it is sufficiently weakly muffled, on his part

The invention is based on the drawing in more detail, approximately exponentially decaying bending speed

explained. It shows 45 gungcn through. Strictly speaking, this process is

Fig. 1 a single gear tooth with excitation coil no longer periodically. Usually one speaks

and capacitor as well as with electrical pick-up but also here of one period and understands

and display devices, under the period of the underlying harmonic

Fig. 2 see two approximately exponentially decaying natural oscillation, whose natural frequency / _β is

Vibration processes of a tooth with a linear Or- 50 with the simplistic assumption of a single

DIN-scale, massless beam clamped on one side with a

Fig. 3 two approximately exponentially decaying point masses / 71 calculated at the end:
Vibration processes of a tooth after rectification at the logarithmic ordinate scale and j _ \ / (2 ^ Vm ⁷ C)

4 shows a contact yoke with excitation coil, iron core 55. ^B.

and transducers. ^mi

The gear single tooth 1 can simply as flexural rigidity E c = ^3/7/3,

one-sided clamped, capable of bending vibrations - geometrical moment of inertia /,

ger bars can be viewed. The clamping point in modulus of elasticity E,

the gear body assumed to be rigid is located in 60 _n ., ...

, at the tooth root 2; the free end of the bar becomes bar length /.

formed by the tooth tip 3. Approximately lower

- The axis of the exciter is on the right on flank 4 - With a constant point mass m , the knowledge

rinse 5, while the electrical pick-up 6 counter to the natural frequency J _n that is, statements about the

is attached over the other flank 7. This flexural strength c. Similar relationships exist

order on two different flanks became the hen in the real tooth 1 with distributed mass and

Chosen for the sake of clarity of the drawing; they variable area moment of inertia. Which then

is also to be preferred for constructional reasons .. only theoretically possible after complicated calculations

, Zugebende natural frequency / _ß is inter alia strongly dependent on the module; it is around 35 kHz for module 10 and around 100 kHz for module 3.

During the duration of the impact, two vibratory systems, an electrical and a mechanical, Coupled with each other via the magnetic field, but limited in time by the thyristor 8. The energy that is initially stored in the electrical system is only then transferred to the me-

with a small temporal voltage change around the positive peak value of the mains voltage in the Turns on around the middle of their half-cycle. The switch-on time must then be related to the zero passage the mains voltage with sufficient accuracy in the periodic operation according to the invention are complied with so that z. B. on the oscilloscope 15 standing images. This direct Feed-in from the AC grid is

can swing freely, transfer with low loss if / b < h , that is, if the duration of the impact is less than a half cycle of the natural bending oscillation of the counter 1

The above calculated natural frequency / _{ß of} a unilaterally clamped massless beam with a point mass at the end for flexural vibrations and that of a tooth will be used in practical

Mechanical system in which no energy 10 is possible at the beginning, because the tooth was previously excited in a jerky manner is contained, which, however, in contrast to the electric oscillates in a time that is compared to very small a half cycle of the mains voltage can be viewed.

The curve 20 shows the course of a voltage that changes over time in the u (/) diagram, which would be displayed on the oscilloscope 15, for example. Both the voltage (w) and time (/) axes are divided linearly. The applied voltage u is the output voltage of the transducer 6 and thus the

Make measurements only if there is sufficient homogeneity in the deflection As of the tooth flank 7 in the illustrated. Deviations from it, such as B. the blow hole 3 example proportional; However, open-12, hardness crack 13 or pitting can also be used for the first or second time derivation through fatigue-heralding crack 14, influencing deflection A s , without changing the stress distribution, among other things thereby changing the Determination of the natural frequency j _B and which fundamentally changes the geometrical moment of inertia / and thus the flexural strength of the decay time T _A. The natural frequency c and natural frequency j _n . In addition, additional frictional damping occurs at the quenz / _ß from half the number of passages cracks, which one of the curve 20 is derived through the / axis in a faster conversion of the vibration energy in a suitably selected time unit; the decay heat has the consequence and thus the oscillation time T _A results as the abscissa on the / axis, which can decay in a shorter time. The connection 30 can be cut off by the initial tangent 21 to the envelope curve of the envelope curve of the vibrations in the dependent e-function 22. The peak values of the time / in good approximation by one of the voltage η have decayed after the expiration of 5 T _A on the wee function jfc · & - ' ^lT A , with constant k n less than 1 ⁰ Zo of their initial value, so that and Decay time (time constant of the envelope curve - then, in the example approximated to time T ₁ , a new exponential function) T _A. Both the natural frequency / _ß and 35 excitation of the tooth 1 can be provided. When the decay time T _A or dependent variables are the direct current supply at the terminals 17, 18 one is the curve display of the oscilloscope 15 and / or
another analyzer for vibration parameters
16 can be found. Other common parameters for
the attenuation can under the condition 40
T _A > Mfβ can be converted into one another as follows:

in the choice of time T ₁ , relatively free to choose

with decay constant δ _Α , degree of attenuation &, logar. When feeding from the alternating current network, this time T _{n is} determined by its periodicity.

The construction of the initial tangent 21 to the envelope curve e-function can for example thereby be circumvented that the oscilloscope 15 the time-varying rectified output voltage of the transducer 6 or the voltage I μ I proportional to it on a logarithmic scale, as log | η |, with a linear time deflection. As a result, an approximate straight line 23 is used as the envelope curve of the

ment A, resonance sharpness of an oscillator Q (quality of an equivalent electrical oscillating circuit).

Assessment of the measurement results of each
Teeth of a gear is expediently on
Hand — of deviations — from nominal values made — one-sided Schcitel values 24 reached; the. Amount of the mejp ^ iög ^ oilwerter, -for example, in the case of the 'slope of the straight line is' proportional to IjT _34. ' Prefixed ^ test ^ nes [used gear from the ^ 50 part; one uses the günsögere-isubjekfiye InterpoiiSttefw ^^ i ^ | u | ä * _; ] 7 ^ ί allCT ^ his teeth formed, possibility of a straight line to emer.TC £ reading or ^: b ^ rder ^ anra ^ gXichen * series production, neier \ 2ahn- from £ by ^ byl the first 5ch'eiwert 25 of the time wheels ~ Ojiality requirements are taken into account. Dear. verifiable peak values 24 ^ constant "with, in" 15estimmter! limits, can be generated by a τύ B \ Zeitlich TechteckfSnnigiVeranderTiche VergenuFei5tierung "" def ^s i \ Tiwejctiungen von / 3 "and T _A 55 equal spanuhg ^ and additionally, represented In the case of blowholes 12, for example, the // j- ^ ren chisel values26 are constant 'and ^ a defined ab ^ eicTruti is more pronounced than, the! ^ - deviation, bay)],' ζ ,, Β? -1 / (2 e) = 0.1353, the first vertex

^ .iis-SL ^ i— ^ «-.-'-: i ~ iu" - Tre ^; i5; ibetragfeii, .for a 'constant propriety

25 ₇ 26 ^ υί Jlem: Screen of the Pszilldskojisl 15 provides ^ calibration of the 'yeptarkung factors ^ .- iiie-deflection time' by * raster division or S. Όΐϋΐιΐ, '- τιηα, ^ ΐβ ^ ζηηι Sdinittpunkt defGstraaden ^ and 26 belonging time 2f yes ^ bfiest, daldieTScheiy values 24, within "the Zfciki / äsTä on, 1; (2e) decay (meaningful ^ at an-,

• r> -. Iro-rrr --— r- ο from a change of 65 their fractionsi). *. ^ - C ~~ - \

^ ßst'ix in many cases "is not necessary," ^ he reading accuracy for "the time 2 - t _A will be eremenTöleiclistfom betweenjikreisvot if 3ioht" when one is especially with direct supply ^:., j ^ - w'i. ^ -. ο only 'at the end Vines from the Wcchsclstromnclz from the "delay" of the

The capacitor 9 'is charged ^ out of a spam runfisquelie ^1, not shown ^ which "is connected to the terminal

Time diversion between the times T ₁ and T _n makes use, so that the oscillation process of interest appears as large as possible on the screen of the oscilloscope IS. The peak values 26 of the reference voltage are chosen so that the interference voltage definitely does not affect the reading. In the example shown, the interference voltage can be 5% of the first peak value 25 without hesitation. The natural frequency / _β is derived from half the number of semi-oscillations in a suitably selected time unit in the logarithmic representation of the time-variable rectified output voltage of the transducer 6 or the voltage u proportional to it.

For example, the parts of the excitation coil 5, the transducer 6 and the iron core 11 with a return path are advantageous combined with a handle 27 in a yoke 28, 29. The exciter part 28 of the application yoke 28, 29 is made of magnetizable material. The measuring part 29 made of non-magnetic material has two mating surfaces 30, 31 on an adjacent one in the example shown Tooth 32 is sufficient for point or line contact. The transition area 33 between the other adjacent tooth 34 and the iron core II, on the other hand, the flank surface must be as possible be well adapted to keep the consumption of magnetic voltage for this transition low. The other crossing over against the flank 4 must, however, have an air gap so that the to testing tooth 1 can swing freely. The same requirement applies to transducer 6. The supply lines to the thyristor 8 and to the capacitor 9 are via the connection 35, the leads to the oscilloscope 15 and to the analyzer for vibration parameters 16 are led via the connection 36.

While in most cases the inspection of transmission gears without removing them, possibly After opening gearbox covers or the like, this is possible with the aid of the manually operated contact yoke 28, 29 is, an automated test device, for example, requires the gear to be tested to be clamped. An actuator is used to operate a yoke similar to 28, 29, which is part of this test device. which actuates it in a substantially radial reciprocating manner while the gear to be tested is moving rotates one tooth at a time.

It is advantageous to use the automated test device described with a measuring device for flank shape, Assemble edge direction and / or pitch errors. This makes it possible to use the Saving the time required to clamp and unclamp the gear to be tested.

For this purpose 2 sheets of drawings

Claims (7)

Error a well-known process. It is based on the claims that impact energy is transmitted to the objects to be tested by knocking or hitting them 1. Procedure for testing the flexural rigidity and that the impulse response consisting of Freund Damping of individual gear teeth from 5 frequency spectrum (sound) and temporal decay of the Steel, in particular for the determination of faulty vibrations (damping), information about even conveyed existing errors based on free, electrically measured bending potential. This simple one vibrations after shock-like excitation characterized in that the tusks do not directly energize for the following reasons be turned on the tooth (1) by attraction forces io: is transmitted in a magnetic field (1.0), The frequency of the natural bending vibrations of a that a flow surge in an excitation coil of Zahn is in the inaudible ultrasound range, and (S) generated. the duration of the impact, e.g. B. with a hammer blow, 2. The method according to claim 1, characterized by a multiple of the period of the bending, that the shock-string excitation peri- 15 natural oscillation of a tooth, so that the shock energy is repeated odically. only very imperfectly or not at all 3. Process according to AnsDruch2, whereby counter energy is converted. The duration of the burst indicates that the repetition frequency should expediently be about a half-period burst-like Excitations equal to the network duration of the natural bending oscillation of a tooth defrequency or speak by multiplication or divi- ao or be less than these. There are already sion with an integer is obtained from it. objective procedures (DT-PS 7 51715, DT-AS 4. Arrangement for carrying out the method 2146 132, DT-AS 2147641) to determine the according to one of claims 1, 2 or 3, da- frequency and the attenuation in free, exponential characterized in that decaying oscillation processes for the production of shock-like des Flood shock a previously charged * s excitation known, which will be used where the capacitor (9) through the excitation coil (5) charges the accuracy requirements and / or the height. the frequency is no longer a subjective evaluation 5. Allow the order to carry out the procedure. These procedures use an electrical system one of claims 1, 2 or 3, thereby seeing the transducer, the one of the deformation of a free characterized in that the excitation coil (5) to the 30 oscillating system analog measurement voltage to a Secondary winding of a transformer emits electronic evaluation circuit; the butt-closed is, through whose primary winding-like excitation of the system happens, however, further in previously charged capacitor (9) discharges. mechanical knocking or hitting 6. Arrangement according to claim 4 or 5, with a shock that is too long for tooth bending vibrations, characterized in that the natural frequency / _£ 35 is permanent. of the resonant circuit from the capacitance C _E of the Capacitor (9) and the inductance L _n of the measurement according to the decay method through excitation coil (5) approximately the same size as the lead when the natural vibrations, such as natural bending frequency / _{e of} the tooth (1) or greater z. B. with teeth, are in the ultrasonic range, wild than this is. 40 often after constant excitation of the test 7. Anordniirg according to one of Claims 4, 5 lings with its natural frequency the necessary for this or 6, characterized in that the energy supply is switched off abruptly. Then charge of the capacitor (9) by a control follows the free, almost exponentially decaying impulse is initiated, which is one in the discharge decay process, which is to be evaluated well (measuring Circuit arranged thyristor (8) from the 45 and testing / automatic, 1973, issue July / August, locked into the conductive state. P. 478 and September issue, p. 575). The transfer the vibration energy before switching off on test specimens made of steel is carried out if necessary Forces of attraction in a magnetic field that 50 by an alternating flow in an excitation coil is generated, which is connected to an oscillator tuned to the natural frequency. the The invention relates to a method and the necessary prior knowledge of the self-regulation for checking the bending stiffness and damping, however, complicates the measuring process. The resofung of individual gear teeth made of steel, in particular an increase in vibration amplitudes more to determine defects, based on free, heavily dependent on attenuation and requires z. B. at Electrically measured bending vibrations are readjusted or regulated after each impact like suggestion. the oscillator output power in the interest of constant For assessing the condition of highly angry sensitivity. said gears at the beginning and during their 60. Furthermore, it is already known from the literature, Lifespan is a non-destructive test method Impact energy on a test object is too excessive, that among other things material defects, gene that a surge in an electromakleine Hard cracks at the tooth base and beginning. An magnetic coil is generated, cracks due to material fatigue on the flanks The invention is based on the object that indicates before breakage and flank destruction are 65 non-destructive testing methods of the sound sample appear. art to design that in the ultrasonic In the case of objects whose natural vibrations are the natural bending frequencies of Zahnbar in the audible range, the subjective sound test can be applied to similar individual wheel teeth made of steel.