JP2008241375A - Detecting method of eccentricity of master gear and gear to be inspected, and eccentricity detecting device using method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detecting method of eccentricity of a master gear and gear to be inspected that does not require previous measurement of the vibration of the master gear and does not require periodic vibration measurement of the master gear, and to provide an eccentricity detecting device used for this detecting method. <P>SOLUTION: The gear ratio between the master gear and gear to be inspected is set substantially m/w (where, m≥2, w≥2, m+w=2n+1, m and w do not have a common factor, and m and w are natural numbers). The master gear and gear to be inspected mesh with each other by pressure-contact, the variation of the distance between the centers of both gears while the master gear rotates w times is recorded, and the eccentricity of the rotation centers of the master gear and the gear to be inspected is detected by dividing the record of the variation into two and calculating it. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gear inspection method, and more particularly to a method for calculating an eccentric amount of a master gear and a gear to be inspected from a relative movement amount of a master gear and a gear to be inspected, and a gear to be inspected using this method. The present invention relates to an inspection apparatus for the amount of eccentricity.

  The “gear inspection device” that measures and determines the accuracy of the gear rotates the gear to be inspected to mesh with the master gear and rotates the gear to be inspected according to the amount of movement of the gear to be inspected. (2) O. B. D. Inspection items such as (overball diameter) and (3) dent are inspected. Then, the runout of the tooth gap of (1) of this inspection item is obtained by the difference in the movement amount of the gear to be inspected, and the O.D. B. D. Is obtained by adding the average value of the movement amount of the gear to be inspected to the reference dimension, and the dent in (3) is obtained by subtracting the average value from the maximum value in one gear of the gear to be inspected. It is done.

Since the master gear used in the gear inspection apparatus is a reference gear, it is required to have extremely high accuracy of tooth traces, tooth diameters, and meshing groove portions.
For example, if there is a shake in the master gear, the value of this shake is added to the value of the shake of the gear to be inspected as it is, so if the meshing position is different, the difference in the phase of the added master gear will cause Variation (error) increases. For this reason, it is required to improve the accuracy of the master gear run-out. Even if the master gear run-out accuracy is aimed at “0”, a core metal is inserted into the inner diameter of the master gear. In order to attach to a gear grinder on the basis of this, a misalignment error occurs, and even if it can be processed with high accuracy, it can often be processed only with a deviation of about 3 to 5 μm or an error of about 8 μm.

  Therefore, in a gear inspection device that uses a master gear, by correcting the sine wave-like shake caused by the master gear, the master gear shake is brought close to “0” and only the shake value of the gear to be tested is measured. It is required to do.

There are the following two methods for correcting the shake of the master gear. One of them is
(1) By making the master gear larger than the number of teeth of the gear to be inspected, for example, about 8 times or more, it is not necessary to use one turn of the master gear (the full width of the master gear runout). The gear shake can be reduced to about 1/3 of the size of one round.
However, this method has a problem that it becomes difficult to install equipment because the master gear becomes large. In addition, when the master gear used is worn, the gear measurement method inspecting the normal gear to be inspected cannot detect the wear of the master gear itself. It is necessary to periodically determine whether or not the monitor gear with high accuracy can withstand use.

The other is
(2) While rotating the master gear around the core bar, drop the dial gauge probe into each tooth gap and measure all the tooth gaps. When measuring the gear to be inspected, the deviation of the tooth gap of the meshed master gear is subtracted from the data, and the master gear shake is corrected to be “0”. However, since the master gear tooth gap and runout data need to correspond 1: 1, it can be used as correction data by adding a mark that serves as a reference for the rotation direction (phase) of the master gear. become.

Incidentally, there is a technique disclosed in Japanese Patent Laid-Open No. 6-241769 as a method for correcting the eccentricity of the master gear. The purpose of this technology is to "provide an eccentricity correction method for a master gear in a two-tooth meshing gear test that can achieve both accuracy improvement and cost reduction." The master gear eccentricity correction method in the related two-tooth meshing gear test sets the number of teeth of the master gear so that it does not have a common prime factor with respect to the number of teeth of the calibration gear. The master gear having a number and the calibration gear are rotated with each other in a meshed state of two teeth, and the amount of variation in the center-to-center distance obtained by this rotation is measured for each tooth of the master gear. The amount of fluctuation of the measured value for each tooth is measured, and the amount of eccentricity at the rotation center of the master gear and the overall correction amount for the tooth gap fluctuation for each tooth of the master gear are calculated. To have "one in which was solved by a method.
JP-A-6-241769

  However, in the technique disclosed in Japanese Patent Laid-Open No. 6-241769, the number of teeth of the master gear is set so as not to have a common prime factor with respect to the number of teeth of the calibration gear, and the master gear and the calibration gear are set. The amount of variation in the center-to-center distance must be measured for each tooth of the master gear, and the master gear needs to be prepared for each calibration gear. It takes time and labor to measure. Further, it is the same as in the prior art that the master gear runout must be periodically measured to know when to replace the master gear.

  Therefore, the present invention does not require the master gear run-out to be measured in advance, does not require periodic master gear run-out measurement, and does not require a mark as a reference for the rotation direction of the master gear. It is another object of the present invention to provide a method for detecting the amount of eccentricity of a gear to be inspected, and to provide an amount of eccentricity detection device used in this detection method.

In order to achieve the above object, the method for detecting the eccentricity of the master gear and the gear to be inspected according to claim 1 of the present application is such that the ratio of the number of teeth of the master gear to the number of teeth Zw of the gear to be inspected is approximately m. / W (where m ≧ 2, w ≧ 2, m + w = 2n + 1, and m and w do not have a common factor, and m, w, and n are natural numbers), and the master gear and the The gears to be inspected are in pressure contact with each other, the master gear rotates approximately w and the gear to be inspected rotates approximately m, and the center-to-center distance varies with the rotation of the master gear and the gear to be inspected. The amount is recorded with a time axis, and when the time when the master gear rotates about w or the gear to be inspected rotates about m is [t], the recording is the first of time [0 to t / 2]. Record and time [t / 2 ~ The second recording time is divided into two, and the first recording time [0] is changed to the second recording time [t / 2] and the first recording time [t / 2]. ] At the time [t] of the second recording, and the amount of fluctuation of the second recording is added to the amount of fluctuation of the first recording arranged at each time, and / or the first recording The amount of eccentricity of the center of rotation of the master gear and the gear to be inspected is calculated by subtracting the amount of variation of the second recording from the amount of variation of.
The time [t] includes a parameter that can be converted into a time such as the rotation speed, rotation angle, angular velocity of the master gear and / or the gear to be inspected, or the number of meshes of the master gear and the gear to be inspected.
Further, the method for detecting the eccentric amount of the master gear and the gear to be inspected according to claim 2 of the present application is the method for detecting the eccentric amount of the master gear and the gear to be inspected according to claim 1, wherein the master gear and the gear to be inspected are detected. The gear ratio Zm / Zw of the gear to be inspected is characterized by being within 100 ± 2% of the m / w.
The method for detecting the eccentricity of the master gear and the gear to be inspected according to claim 3 of the present application is the method for detecting the eccentricity of the master gear and the gear to be inspected according to claim 1 or 2, The m / w is 2/3 or 3/2.
Further, the eccentricity detecting device for the master gear and the gear to be inspected according to claim 4 of the present application includes a master gear having the number of teeth Zm in pressure contact with the gear to be inspected having the number of teeth Zw, the master gear and the gear to be inspected. A pressure-engagement portion for pressure-meshing the inspection gear, a drive portion for driving the master gear or the gear to be inspected, and a rotation speed for detecting the rotation speed of the master gear and / or the gear to be inspected A detector, a variation measuring unit for measuring a variation in the distance between the centers of the master gear and the gear to be inspected, and a variation measured by the variation measuring unit are recorded on a time axis. And a gear ratio Zm / Zw between the master gear and the gear to be inspected is approximately m / w (where m ≧ 2, w ≧ 2, m + w = 2). +1, and m and w do not have a common factor, and m, w, and n are natural numbers.), And the time that the master gear recorded in the fluctuation amount recording unit rotates approximately w [ The amount of eccentricity of the center of rotation of the gear to be inspected is calculated from the information of t], and the amount of eccentricity of the center of rotation of the master gear is calculated.
An eccentricity detecting device for the master gear and the gear to be inspected according to claim 5 of the present application is the eccentricity detecting device for the master gear and the gear to be inspected according to claim 4, wherein the master gear and the object to be inspected are detected. The gear ratio Zm / Zw of the inspection gear is characterized by being within 100 ± 2% with respect to the m / w.
An apparatus for detecting the amount of eccentricity of the master gear and the gear to be inspected according to claim 6 of the present application is the device for detecting the amount of eccentricity of the master gear and the gear to be inspected according to claim 4 or 5, wherein / W is 2/3 or 3/2.

The present invention is a shake of the master gear and the gear to be inspected from a record of the amount of change in the distance between the centers due to a predetermined number of rotations, with the gear ratio of the master gear and the gear to be inspected being a predetermined integer value ratio. The amount of eccentricity is calculated. For this reason,
(1) Without measuring the deflection of the master gear in advance, it is possible to obtain the deflection value of the gear to be inspected accurately by meshing with the gear to be inspected and obtaining and calculating the deflection data. it can.
(2) Since master gear runout data is not required, there is no need to put a reference mark on the master gear for obtaining master gear correction data.
(3) It is not necessary to set a mark serving as a reference for the master gear as a measurement start point, and measurement can be started from the position where the marks are engaged.
(4) Since the value of the master gear runout can be known during measurement of the normal runout of the gear to be inspected, it is possible to accurately determine the replacement time of the master gear, and the standard of the gear to be inspected (example There is no need to make a monitor gear.
(5) Further, a combination of m and w where “m ≧ 2, w ≧ 2, m + w = 2n + 1, and m and w do not have a common factor, and m, w, and n are natural numbers”. Since the minimum number in “2 and 3” or “3 and 2” and the gear ratio Zm / Zw between the master gear and the gear to be inspected is within 100 ± 2% with respect to m / w, The versatility by which one master gear can be used for a plurality of types of gears to be inspected increases.
By setting the tooth number ratio Zm / Zw within 100 ± 2% with respect to m / w, the measurement error becomes about ± 1 μm or less of the normally required allowable range.

  FIG. 1 to FIG. 1 show one embodiment of a master gear and inspected gear eccentricity detecting device and a method of detecting the eccentricity of the master gear and inspected gear according to the best mode for carrying out the present invention. This will be described with reference to FIG. FIG. 1 is a schematic view of an eccentricity detecting device for a master gear and a gear to be inspected according to the embodiment, FIG. 1 (a) is a plan view, FIG. 1 (b) is a side view, and FIG. FIG. 3 is a graph of the fluctuation amount of the center-to-center distance accompanying the rotation of the master gear and the gear to be inspected. FIG. 3 is a time axis representing the graph of the fluctuation amount of the central axis accompanying the rotation of the master gear and the gear to be inspected in FIG. It is the graph which divided into 2 with respect to (X axis), and was arranged up and down.

  In FIG. 1, reference numeral 1 denotes an eccentricity detecting device for the master gear and gear to be inspected (hereinafter simply referred to as “eccentricity detecting device”), reference numeral 11 denotes a master gear, and reference numeral 13 denotes a gear to be inspected. Reference numeral 30 is a pressure-engaging portion, reference numeral 31 is a base, reference numeral 33 is a main shaft holder, reference numeral 35 is a master gear mounting shaft, reference numeral 37 is a ball bearing, reference numeral 39 is a slide unit base, reference numeral 41 is a slide unit, and reference numeral 43 is a cover. Gear bar for inspection, reference numeral 45 is a spring, reference numeral 50 is a drive unit, reference numeral 51 is a motor, reference numeral 53 is a motor side pulley, reference numeral 55 is a master gear side pulley, reference numeral 57 is a belt, reference numeral 70 is a rotation speed detection unit, Reference numeral 71 is a rotary encoder, reference numeral 73 is a coupling, reference numeral 80 is a fluctuation amount recording unit, reference numeral 90 is a fluctuation amount measuring unit, and reference numeral 91 is a detection unit. Vessel, reference numeral 93 is a slide unit protruding pieces.

As shown in FIG. 1, the eccentricity detection device 1 mainly includes a master gear 11, a gear 13 to be inspected, a pressure-engagement unit 30, a drive unit 50, a rotation number detection unit 70, a variation amount recording unit 80, and a variation amount. The measuring unit 90 is configured.
Here, if the pressure-engagement unit 30, the drive unit 50, the rotation speed detection unit 70, the fluctuation amount recording unit 80, and the fluctuation amount measurement unit 90 are the eccentric amount detection device main body, the master gear 11 and the gear 13 to be inspected are eccentric amounts. It is formed so as to be detachable from the detection device main body, and the master gear 11 can be appropriately replaced according to the number of teeth of the gear 13 to be inspected, the shape of the teeth, and the like.

  The press-fit engagement portion 30 is mainly fixed to a base 31 fixed on the floor, a main shaft holder 33 fixed to the base 31 and rotatably supporting a master gear mounting shaft 35 via a ball bearing 37, and the base 31. The slide unit base 39 and the slide unit 41 that slides in the direction of the spindle holder 33 by being urged by a spring 45 on the slide unit base 39 are configured. An inspected gear core 43 is erected on the slide unit 41.

The upper part of the master gear mounting shaft 35 pivotally supported by the spindle holder 33 is formed so that the master gear 11 can be fitted, and the lower part of the master gear mounting shaft 35 is connected via a coupling 73. A rotary encoder 71 is attached.
The rotary encoder 71 and the coupling 73 constitute a rotational speed detection unit 70, and the rotational speed detection data acquired by the rotational speed detection unit 70 is sent to the fluctuation amount recording unit 80.

  The drive unit 50 includes an electric motor 51, a motor-side pulley 53 fitted to the rotation shaft of the electric motor 51, a master gear-side pulley 55 fitted to the master gear mounting shaft 35, and the motor-side pulley 53 and the master gear side. The belt 57 is stretched around the pulley 55, and the master gear mounting shaft 35 is rotated by the rotation of the electric motor 51.

  The fluctuation amount measuring unit 90 includes a detector 91 and a slide unit protrusion 93 projecting from the slide unit 41, and the tip of the detector 91 lightly presses the surface of the slide unit protrusion 93 to be in close contact with it. is doing. As the slide unit 41 moves, the slide unit projection piece 93 also moves, the amount of movement is detected by the detector 91, and the moving distance of the slide unit 41 relative to the spindle holder 33 is detected. The detected movement distance data is sent to the fluctuation amount recording unit 80, and the fluctuation amount recording unit 80 records the movement distance data in synchronization with the data acquired by the rotation speed detection unit 70.

  Next, an example of the procedure for measuring the amount of eccentricity of the gear 13 to be inspected using the eccentricity detecting device 1 will be described.

(1) First, the master gear 11 corresponding to the number of teeth and the tooth shape of the gear 13 to be inspected is selected. When the number of teeth of the gear 13 to be inspected is Zw, the number of teeth Zm of the master gear 11 is determined so as to satisfy Zm / Zw≈m / w. Here, m and w are m ≧ 2, w ≧ 2, and m and w are natural numbers having no common factor. Further, from m + w = 2n + 1 (n is a natural number), one of m and w is even and the other is odd. Of course, Zm and Zw are not limited to even and odd numbers. Zm / Zw is best matched with m / w, but does not necessarily match m / w, and may be within m / w × (100 ± 2)%.

(2) When the master gear 11 is fitted to the master gear mounting shaft 35 and the gear 13 to be tested is fitted to the gear core 43 to be tested, the gear 13 to be tested is moved in the direction of the master gear 11 by the spring 45. Energized and press-engaged with the master gear 11.

(3) When the electric motor 51 is switched on, the electric motor 51 rotates. The rotation of the electric motor 51 rotates the master gear mounting shaft 35 via the motor side pulley 53, the belt 57 and the master gear side pulley 55. . As the master gear mounting shaft 35 rotates, the master gear 11 and the gear 13 to be inspected rotate.

(4) Along with the rotation of the master gear 11 and the gear 13 to be inspected, the rotation number detector 70 detects the rotation number (or rotation angle, angular velocity, etc.) of the master gear 11, and the fluctuation amount measurement unit 90 detects the master gear 11. The amount of change in the relative center-to-center distance of the gear 13 to be inspected is detected, and the rotational speed data and the fluctuation amount data are synchronized and recorded in the fluctuation amount recording unit 80. It continues to be taken while the master gear 11 rotates w.

(5) When the recording time during which the master gear 11 of the recording obtained in the above (4) rotates w is [t], the recording in (4) is the first of the time [0 to t / 2]. The recording is divided into the second recording of time [t / 2 to t], the first recording time [0] is changed to the second recording time [t / 2], and the first recording time The time [t / 2] is opposed to the time [t] of the second recording, and the variation amount of the second recording is added to the variation amount of the first recording arranged for each time, and / or the first recording time. By subtracting the second recording fluctuation amount from the recording fluctuation amount, the eccentric amount of the rotation center of the master gear and the gear to be inspected can be calculated.
In the above (1), m and w are m ≧ 2 and w ≧ 2, respectively. For example, when m / w is 2/1, the master gear 11 and the gear 13 to be inspected are When the same high-order component is present, the high-order component of the gear 13 to be inspected becomes the primary component of the master gear 11, and the difference between the first recording fluctuation amount and the second recording fluctuation amount is determined. This is because the higher order component of the gear 13 to be inspected is canceled by “pulling”.

(6) Then, the “tooth groove runout” is directly obtained from the eccentric amount of the rotation center of the gear to be inspected, and the average value of the movement amount of the gear to be inspected is added to the reference dimension to obtain “O. BD "is obtained, and" dent "is obtained by subtracting the average value from the maximum value in one gear of the gear to be inspected.

  Here, a method for detecting the amount of eccentricity of the master gear and the gear to be inspected will be described with reference to FIGS.

In the embodiment, as the model case, the numerical values of the master gear 11 and the inspected gear 13 are determined as follows.
Number of teeth of master gear 11 ... 25
Number of teeth of gear 13 for inspection ... 37
Runout of master gear 11: 20 μm
Runout of gear 13 to be inspected ... 40 μm
Note that the shake of the master gear 11 and the shake of the gear 13 to be inspected are originally unknown numbers, but are set as described above for easy explanation.

  Zm / Zw, which is the ratio of the number of teeth of the master gear 11 to the gear 13 to be inspected, is 0.6756... Since this corresponds to 1.014 when m / w is 2/3, the master gear 11 satisfies “m / w × (100 ± 2)% or less” which is a requirement according to the present invention. Further, when the master gear 11 is rotated three times, the inspected gear 13 is rotated 2.027 times, and therefore, in the embodiment, description will be made based on data examples when the master gear 11 is rotated three times.

2 and 3, the vertical axis (Y axis) is the amount of fluctuation (runout width (μm)), the horizontal axis (X axis) is the time required for a predetermined rotation, and the solid line is “master gear + covered”. The variation amount of the “inspection gear”, the broken line the variation amount of the “master gear”, and the dotted line the variation amount of the “inspected gear”. 2 and 3 is a point when the distance between the centers of the master gear 11 and the gear 13 to be inspected is “0”. There are some deviations that can be corrected. This correction method will be described later.
In FIGS. 2 and 3, the time for which the master gear 11 rotates three times is [t].

  As shown in FIG. 2, the fluctuation amount (solid line) of “master gear + gear to be inspected” is obtained by adding the fluctuation amount (dotted line) of “gear to be inspected” to the fluctuation amount (dashed line) of “master gear”. is there. The fluctuation amount of the “master gear” and the fluctuation amount of the “gear to be inspected” draw a sine wave, and during the time [0] to [t], the sine wave drawn by the “master gear” is 3 cycles, The sine wave drawn by “inspection gear” is 2.027 cycles, that is, approximately two cycles.

The graph of FIG. 2 is divided into two parts from time [0] to [2 / t] and [2 / t] to [t] and arranged vertically, and the graph of FIG. 3 shows fluctuations in “master gear”. As for the graph of quantity (broken line), although the sign is reversed, the absolute value is the same, and for the graph of the amount of variation (dotted line) of “inspected gear”, the sign is the same and the shape is the same. It has become.
For this reason, the graph of the fluctuation amount (solid line) of “master gear + gear to be inspected” is shown in the first record from time [0] to [2 / t] and the second record from [2 / t] to [t]. The first recording time [0] is set to the second recording time [t / 2], and the first recording time [t / 2] is set to the second recording time. By placing the second recording fluctuation amount on the time [t] and adding the second recording fluctuation amount to the first recording fluctuation amount opposed at each time, only the fluctuation amount of the “master gear” is canceled and doubled. The amount of fluctuation of the “inspected gear” is determined. Therefore, the record of the fluctuation amount of “master gear + gear to be inspected” is divided into the first record and the second record, and the maximum value and the minimum value of the sum of the first record and the second record are added. The deviation of the gear to be inspected can be obtained by dividing the value obtained by subtracting the value by [2].

The master gear run-out can be obtained by subtracting the known run-out of the gear to be inspected from the fluctuation amount of “master gear + gear to be inspected”. Dividing the quantity of records into two parts, the first record and the second record, and then subtracting the maximum and minimum values minus the first record and the second record by [2] It is also possible to obtain the master gear runout.
In the embodiment, the “0” point on the Y axis in FIGS. 2 and 3 is a point when the distance between the centers of the master gear 11 and the gear 13 to be inspected is “0”. Even if the “0” point is slightly shifted, the first recording and the second recording are added or subtracted, and the maximum value and the minimum value obtained there are added to be halved. be able to.

  In the embodiment, m / w of the master gear and the gear to be inspected is 2/3, but the number of teeth of the master gear may be larger than the number of teeth of the gear to be inspected, and the m / w is “m ≧ 2, w ≧ 2, m + w = 2n + 1, and m and w do not have a common factor, and m, w, and n are natural numbers. ”and the actual tooth ratio is m / w Of course, it should be within x (100 ± 2)%.

As described above, in the present invention, the eccentricity of the master gear and the gear to be inspected is recorded from the record of the amount of change in the center-to-center distance while the master gear rotates w and / or the gear to be inspected rotates m. Since the master gear runout can be obtained directly from the amount of eccentricity, there is no need to measure the master gear runout in advance, and the master gear runout is required for each inspection. Therefore, it is possible to accurately determine the replacement timing of the master gear, and it is not necessary to manufacture a monitor gear that serves as a reference (exemplary model) of the gear to be inspected.
Further, when the inspection is started, the meshing of the master gear and the gear to be inspected can be started from an arbitrary position, so that it is not necessary to attach a reference mark to the master gear.
Further, the gear ratio m / w between the master gear and the gear to be inspected is “m ≧ 2, w ≧ 2, m + w = 2n + 1, and m and w do not have a common factor, m, w and Each time the type of gear to be inspected changes, it is sufficient to satisfy the requirement that “n is a natural number” and the actual gear ratio is within m / w × (100 ± 2)%. The number of cases where there is no need to change the number will increase as compared to the conventional case.

1A and 1B are schematic views of an eccentricity detecting device for a master gear and a gear to be inspected according to an embodiment, in which FIG. 1A is a plan view and FIG. 1B is a side view. FIG. 2 is a graph of the amount of change in the center-to-center distance associated with the rotation of the master gear and the gear to be inspected. FIG. 3 is a graph in which the graph of the fluctuation amount of the central axis accompanying the rotation of the master gear and the gear to be inspected in FIG. 2 is divided into two with respect to the time axis (X axis) and arranged vertically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Eccentricity detection apparatus of master gear and gear to be inspected according to one embodiment 11 Master gear 13 Gear to be inspected 30 Pressure engagement portion 50 Drive portion 70 Rotational speed detection portion 80 Fluctuation amount recording portion 90 Fluctuation amount measurement portion

Claims (6)

The ratio of the number of teeth Zm of the master gear to the number of teeth Zw of the gear to be inspected is approximately m / w (where m ≧ 2, w ≧ 2, m + w = 2n + 1, and m and w have a common factor) And m, w and n are natural numbers.)
The master gear and the gear to be inspected are in pressure contact with each other so that the master gear rotates approximately w and the gear to be inspected rotates approximately m,
The amount of change in the center-to-center distance associated with the rotation of the master gear and the gear to be inspected is recorded with a time axis,
When the time for which the master gear rotates approximately w or the gear to be inspected rotates approximately m is [t], the recording is performed with the first recording and the time [t / 2 to time [0−t / 2]. divided into two second recordings of t], the first recording time [0] is changed to the second recording time [t / 2], and the first recording time [t / 2] is matched with the time [t] of the second recording, and the variation amount of the second recording is added to the variation amount of the first recording arranged for each time, and / or the first recording time The master gear and the gear to be inspected are characterized in that the amount of eccentricity of the rotation center of the master gear and the gear to be inspected is calculated by subtracting the amount of change in the second recording from the amount of fluctuation in the recording. Of detecting the amount of eccentricity.   2. The master gear and the gear to be inspected according to claim 1, wherein a gear ratio Zm / Zw between the master gear and the gear to be inspected is within 100 ± 2% with respect to the m / w. How to detect eccentricity.   3. The method of detecting the eccentricity of the master gear and the gear to be inspected according to claim 1, wherein the m / w is 2/3 or 3/2. A master gear whose number of teeth is Zm that is press-fitting to the gear to be inspected whose number of teeth is Zw;
A pressure-engaging portion for pressure-meshing the master gear and the gear to be inspected rotatably,
A drive unit for driving the master gear or the gear to be inspected;
A rotational speed detector for detecting the rotational speed of the master gear and / or the gear to be inspected;
A fluctuation amount measuring unit for measuring a fluctuation amount of a center-to-center distance associated with rotation of the master gear and the gear to be inspected;
A fluctuation amount recording unit that records the fluctuation amount measured by the fluctuation amount measurement unit on a time axis,
The gear ratio Zm / Zw between the master gear and the gear to be inspected is approximately m / w (however, m ≧ 2, w ≧ 2, m + w = 2n + 1, and m and w do not have a common factor) , M, w and n are natural numbers).
The amount of eccentricity of the center of rotation of the gear to be inspected is calculated from the information [time] for the time [t] that the master gear rotates approximately w recorded in the fluctuation amount recording unit, and the amount of eccentricity of the center of rotation of the master gear is calculated. An apparatus for detecting the amount of eccentricity of a master gear and a gear to be inspected, characterized in that:   5. The master gear and the gear to be inspected according to claim 4, wherein a gear ratio Zm / Zw between the master gear and the gear to be inspected is within 100 ± 2% with respect to the m / w. Eccentricity detection device.   6. The eccentricity detecting device for a master gear and a gear to be inspected according to claim 4, wherein the m / w is 2/3 or 3/2.

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