JPS6333977B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dynamic indexing error measuring method for measuring an indexing error between two driving bodies that are driven at a predetermined speed ratio.

In general, mechanical devices employ an indexing function in which two different driving bodies are moved relative to each other at a predetermined speed ratio, and the relative positions of the two are changed in regular steps. In other words, machine tools such as bob machines and gear shapers use a tool shaft that rotates at high speed to accurately index the circumference of a work table that rotates at a low speed and perform gear cutting to create an involute tooth profile.
The indexing accuracy directly affects the accuracy of the resulting gear. Here, the indexing operation between the two driving bodies is
It is greatly affected by the vibration that occurs during driving, and therefore,
The indexing error, which is the displacement difference between the target relative position and the actual relative position between the two driving bodies, needs to be dynamically grasped while they are being driven.

The conventional method for measuring dynamic index error between two driving bodies is to digitize the displacement amount of one driving body over a predetermined time, and to digitize the displacement amount of the other driving body over a predetermined time. The phase difference is determined by digital calculation processing. However, in such a conventional dynamic indexing error measurement method, if a fraction is generated in one of the two driving bodies when converting the displacement amount between the two driving bodies into a digital signal, the indexing error between the two driving bodies increases. There is a problem in that it is impossible to measure with precision.

The present invention has been made in view of the above-mentioned conventional problems, and provides a dynamic indexing error measuring method that can easily and highly accurately obtain the indexing error during driving between two driving bodies. The purpose is to

In order to achieve the above object, the present invention makes it possible to measure the synchronization error, that is, the index error between two driving bodies moving at a predetermined speed ratio, with respect to the displacement position of one of the driving bodies of interest. This is a dynamic indexing error measurement method, and the data processing involves first converting the speed fluctuations of one of the driving bodies of interest into an analog voltage corresponding to slight speed fluctuations with the average speed as zero level, and then The speed fluctuation of the driving body is converted into an analog voltage corresponding to the slight variation in the time required to move the displacement in equal divisions, and by multiplying both of the above analog voltages, the other driving body is moved by the displacement in equal divisions. By determining the voltage corresponding to the synchronization error, that is, the indexing error, between the two subsequent driving bodies, and accumulating this voltage value every time the other driving body moves by equal division, each displacement position of the driving body of interest is calculated. The system continuously measures the synchronization error, that is, the index error.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing one embodiment in which the dynamic indexing error measuring method according to the present invention is applied to a hobbing machine. In this hobbing machine, a work table 11 that rotates at a low speed and a hob shaft 21 that rotates at a high speed are driven at a predetermined angular velocity ratio. work table 1
The digital output of the rotary encoder 12 attached to the rotary shaft of 1 is amplified by a DC amplifier 13, and then amplified by a frequency-voltage converter (hereinafter referred to as
An analog voltage proportional to the angular velocity fluctuation is obtained at the FV converter (FV converter) 14. That is, as shown in the circuit configuration of the FV converter in FIG. 2, a slight variation in the angular velocity of the work table 11 is detected by the DC amplifier 13 as a slight variation in the period of the pulse train 13A of the rotary encoder 12. The pulse train 13A is made into a pulse train 15A with the same height by the limiter circuit 15,
Further, the monostable multivibrator 16 generates a rectangular wave pulse train 16A having the same width and height and whose period changes with the angular velocity fluctuation. Square wave pulse train 16
A is filtered to a low frequency by a low pass filter 17, and an analog voltage proportional to the pulse frequency is obtained. The voltage proportional to the pulse frequency obtained by this low-pass filter 17 is applied to a DC offset device 18.
, the voltage corresponding to the target angular velocity of the work table 11 is removed, and the high gain DC differential amplifier 19 amplifies only the slight voltage fluctuation corresponding to the angular velocity fluctuation.
1 analogized angular velocity fluctuation wave 19A is obtained. In Figure 3A, time t (sec) is plotted on the horizontal axis,
It is an explanatory diagram showing the above-mentioned angular velocity fluctuation wave 19A with the vertical axis representing the angular velocity fluctuation Δω (rad/sec) with the target angular velocity ωmean at zero level.

Further, the digital output of the rotary encoder 22 attached to the hob shaft 21 on the high-speed rotation side is amplified by the DC amplifier 23, and as shown in FIG. 3B, the digital output is period ti
It is detected as a pulse train 23A that fluctuates at (sec).

Next, the dynamic index error measuring device 31 measures the rotary encoder 2 during high speed rotation obtained as described above.
The number of angular velocity fluctuations on the low speed rotation side is analogized by applying the trigger with the output pulse train 23A of 2.
9A is processed to obtain the indexing error between the work table 11 and the hob shaft 21. That is, the dynamic indexing error measuring instrument 31 has a circuit configuration as shown in FIG. Therefore, the corresponding angular velocity fluctuation voltage ai(v) of the analogized angular velocity fluctuation wave 19A on the low-speed rotation side is sampled, and this angular velocity fluctuation voltage ai(v) is given a proportionality constant K( rad/sec/V) is added, and the angular velocity fluctuation amount Kai (rad/sec) on the low speed rotation side corresponding to the predetermined angular displacement position on the high speed rotation side is obtained. On the other hand, the output pulse train 23 of the rotary encoder 22 on the high-speed rotation side
By the simultaneous trigger of A, the oscillation frequency of the crystal oscillator 35A is counted in the time calculator 35B, and the time required for the rotary encoder 22 on the high speed rotation side to rotate by the minimum division angle, that is, the hob shaft rotating at high speed. The time ti (sec) required for 21 to undergo a predetermined angular displacement is calculated.

Furthermore, the time ti (sec) required for the predetermined angular displacement of the hob shaft 21 and the angular velocity fluctuation amount Kai of the work table 11 corresponding to the predetermined angular displacement of the hob shaft 21
(rad/sec) is multiplied by the multiplier 36,
The amount of angular variation of the work table 11 with respect to a predetermined angular displacement of the hob shaft 21, that is, the indexing error (rad) is obtained. In addition, in this embodiment, the hob shaft 2
The angular velocity fluctuation amount Kai (rad/
The angular fluctuation amount Kaiti (rad), which is the integral value of sec), was approximately calculated by the multiplier 36.
uses an integrator, and calculates the angular velocity fluctuation in time ti (sec)
By integrating Kai (rad/sec), it is possible to obtain a more accurate indexing error.

Indexing error at each angular displacement position of the work table 11 and hob shaft 21 obtained in this way
The cumulative value K 〓 ⁱ aiti (rad) is calculated in the accumulator 37 every time the pulse train 23A of the rotary encoder 22 on the high-speed rotation side is triggered. This cumulative value K 〓 ⁱ aiti (rad) is the indexing error at each preceding angular displacement position starting from i = 1.
Cumulative indexing error Δθ in subsequent angular displacement positions obtained by accumulating the influence of Kaiti (rad)
(rad), and is converted from digital to analog every time i increases by 1, and as shown in FIG. 5, each rotational position θ (rad) of the work table 11 on the low speed rotation
It is recorded in the automatic balance type recorder 39 as a cumulative index error curve 38A at . This cumulative indexing error Δθ (rad) is calculated by clearing the memory of the accumulator 37 by the clear circuit 40, and starting calculation with the pulse 12A that is generated once every rotation R of the rotary encoder 12 on the low speed rotation side. , the set rotation amount N of the rotary encoder 12 set in the number setting device 41 is recorded on the recorder 39. Note that the capacity of the accumulator 37 is increased,
By averaging and recording the cumulative indexing error Δθ for each rotation from the first rotation to the Nth rotation of the rotary encoder 12, it is possible to increase the reliability of the measurement results.

According to the above embodiment, the indexing error at each rotational position of the work table 11 and the hob shaft 21 is determined by analog processing in which the analogized angular velocity fluctuation of one is triggered by the rectangular wave signal of the other and integrated. Therefore, as long as a rotary encoder with an appropriate number of pulses is mounted on both rotating shafts in an accurately aligned manner, special measurement skills can be applied to any wide range of rotational speed ratios. It is possible to easily measure the indexing error with high accuracy without the need for precision. In addition, since the speed fluctuation of the work table 11 can be measured by attaching the rotary encoder 12 to the lower surface of the work table 11, it is also possible to easily measure the indexing error during gear cutting. .

In addition, the indexing error measured in the above embodiment is stored in the numerical control device of the hobbing machine, and the work table 11 and the hob shaft 21 are adjusted so that the indexing error is eliminated during actual gear cutting. If each rotational angular velocity is corrected and driven, the gear cutting accuracy of the hobbing machine will be extremely good.

In addition, in the above embodiment, the case where the dynamic indexing error measurement method according to the present invention is applied to a hobbing machine was explained, but the present invention is also applicable to measuring the meshing transmission error of a gear shaper and a gear transmission. It can be applied to dynamic gear meshing testers, as well as motion transmission systems such as timing belts, belts, chains, etc., to measure their angular transmission errors. Furthermore, the present invention is applicable not only to measuring the dynamic indexing error between two rotating axes, but also to measuring the dynamic indexing error between rotational motion and linear motion, such as in a thread cutting machine, a thread grinding machine, etc. Yes, the linear displacement in this case is detected with a linear encoder.
That is, the principle of the dynamic indexing error measurement method of the present invention is that the motion of the two driving bodies is a rotational motion, a rotational motion,
It can be applied to both rotational motion and linear motion, and linear motion and linear motion.

Note that the measurement results of the dynamic indexing error according to the above embodiment include (a) angle division error of both rotary encoders 12 and 22, and (b) both rotary encoders 12 and 22.
Installation error, (c) FV used for angular velocity fluctuation detection part
This includes errors related to the zero point drift of the converter 14 and the linearity of the output voltage with respect to the input frequency, and (d) calculation errors of the dynamic index error measuring device 31.

Here, the errors in (a) and (b) above can be calculated by using a rotary encoder with high angle division accuracy.
This can be reduced by installing joints such as flexible couplings that are accurately aligned with each shaft. The error in (d) above is the angular velocity fluctuation Δω (rad/sec)
This can be reduced by using a rotary encoder on the hob shaft side with a pulse number that generates an appropriate ti (sec) for the fluctuating frequency component.

What most influences the measurement error are the zero point drift and linearity of the FV converter (c) above. To prevent zero point drift, install a capacitor of an appropriate value (one with little leakage), and reduce the angular velocity fluctuation Δω (rad/sec).
can be significantly reduced by removing the very low frequency components of . On the other hand, linearity differs depending on the conversion principle of the FV converter. In the above embodiment, an FV converter using a low-pass filter was shown, but this
When the FV converter shown in FIG. 7 is used as the FV converter, better linearity and responsiveness are ensured. That is, in the FV converter shown in FIG. 7, a slight variation in the angular velocity of the work table 11 is detected by the DC amplifier 13 as a slight variation in the period of the pulse train 13A of the rotary encoder 12, and the pulse train 13A is The limiter circuit 15 generates a pulse train 15A having the same height.
A gate is applied to this pulse train 15A, one pulse time ti of the pulse train 15A is measured using a reference clock pulse (25MHz) from the crystal oscillator 51, and the divider 5
2, calculate its reciprocal i = 1/ti (this is the instantaneous angular velocity). The reciprocal calculation operation is started during the measurement of ti, and at the same time as the measurement of ti is completed, the reciprocal calculation is calculated and stored in the memory 53. Thereafter, the voltage is converted into an analog signal by the DA converter 54, the voltage corresponding to the average angular velocity of the worktable is removed by the DC offset 55, and the voltage corresponding to the angular velocity fluctuation is removed by the high gain DC differential amplifier 56. Only a slight voltage fluctuation is amplified, and an analogized angular velocity fluctuation wave 56A of the work table 11 on the low speed side is obtained.

As described above, the present invention provides a dynamic indexing error that allows the indexing error between two driving bodies moving at a predetermined speed ratio to be measured with respect to the displacement position of one of the driving bodies of interest. This is a measurement method in which the speed fluctuations of one of the driving bodies of interest are converted into an analog voltage corresponding to slight speed fluctuations with the average speed at zero level, and the speed fluctuations of the other driving body are converted into equal divided displacement movements. By multiplying both of the above analog voltages, the indexing error between the two driving bodies after the other driving body has moved by equal division is calculated. By finding the corresponding voltage and accumulating this voltage value every time the other driving body moves by equal division, we are able to continuously measure the indexing error for each displacement position of the driving body of interest. This has the effect that the indexing error during driving between the two driving bodies can be easily and highly accurately measured.

[Brief explanation of the drawing]

Fig. 1 is a measurement system diagram showing an embodiment in which the dynamic indexing error measuring method according to the present invention is applied to a hobbing machine, and Fig. 2 is a circuit diagram showing the configuration of an FV converter used in the same embodiment. Figure 3A is a waveform diagram showing the speed fluctuation on the low speed rotation side in the same example, Figure 3B is a waveform diagram showing the displacement fluctuation on the high speed rotation side in the same example, and Figure 4 is a waveform diagram showing the displacement fluctuation on the high speed rotation side in the same example. A circuit diagram showing the configuration of a dynamic indexing error measuring device, FIG. 5 is a waveform diagram showing the cumulative indexing error in the same embodiment, and FIG. 6 is a waveform diagram showing the rotation speed on the low speed rotation side in the same embodiment. 7th
The figure is a circuit diagram showing a modification of the FV converter used in the same embodiment. 11...Work table, 12...Rotary encoder, 14...FV converter, 19A...Angular velocity fluctuation wave, 21...Hob shaft, 22...Rotary encoder, 23A...Pulse train, 31...Dynamic index Error measuring device, 32...Trigger circuit, 33...
Sampling circuit, 35... Time calculator, 36...
...multiplier, 37...accumulator.

Claims (1)

[Claims] 1. A dynamic indexing error measurement method that allows the indexing error between two driving bodies moving at a predetermined speed ratio to be measured with respect to the displacement position of one of the driving bodies of interest. The speed fluctuation of one of the driving bodies of interest is converted into an analog voltage corresponding to a slight speed fluctuation with the average speed at zero level, and the speed fluctuation of the other driving body is moved by equal division displacement. is converted into an analog voltage corresponding to a slight variation in the time required for
By finding the voltage corresponding to the indexing error between the drive bodies and accumulating this voltage value every time the other drive body moves by equal division, the index error for each displacement position of the target drive body can be continuously calculated. A method for measuring dynamic indexing errors. 2. The dynamic indexing error measuring method according to claim 1, wherein the motions of the two driving bodies are rotational motion and rotary motion. 3. The dynamic indexing error measuring method according to claim 1, wherein the motions of the two driving bodies are rotational motion and linear motion. 4. The dynamic indexing error measuring method according to claim 1, wherein the motions of the two driving bodies are a linear motion and a linear motion.