JP2898108B2 - Non-contact free-form surface measuring device for measuring gear tooth profile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for non-contactly measuring the tooth flank shape of a gear, and more particularly to a method for measuring spur gear, helical gear, etc. using a free-form surface measuring device utilizing holographic interference. The present invention relates to a non-contact tooth surface shape measuring method for measuring tooth surface shapes of various gears.

[0002]

2. Description of the Related Art A gear rotates with a driving gear and a driven gear engaged with each other to transmit power. In other words, more specifically, the tooth surface of the drive gear rotates in the state of meshing with the tooth surface of the driven gear, and power is transmitted. At this time, all machines and devices that operate using power from a power source such as aircraft and automobiles are often provided with a gear device as a speed increasing or reducing device. At this time, if the gear device transmits noise and vibrates in the process of driving the wheels or the propeller device by transmitting the power, the function cannot be sufficiently performed. Therefore, in order to smoothly transmit the power, it has been customary to add a complicated shape correction which is an extremely advanced know-how to the meshing action portion of the gear, that is, the shape of the tooth surface of the gear at the time of processing each gear of the gear device. What is happening is well known. At this time, the gear measuring device for inspecting whether or not a desired tooth surface shape is completed measures the above-described complicated tooth surface correction amount, and converts the measurement result data into a processing machine such as a gear cutting machine or a tooth grinding machine. It has an important role to feed back to the processing work by the side.

[0003] However, the gear measuring device currently used employs a method of tracing the tooth surface with a tracing stylus and calculating an involute curve from the rotation angle of the sampled gear and the length in the normal direction. This method only measures one cross section of one or several teeth of the gear,
As described above, the entire tooth surface is meshed with the tooth surface of the mating part one after another, and the function data or measurement data of the operating tooth surface is insufficient.

In order to overcome this situation, an optical curved surface shape measuring device has been developed which measures not only the tooth surface of a gear but also a general curved surface shape in a non-contact manner using holographic interference. No. 255791 of the present applicant.
No. 1. In the curved surface shape measuring method using this non-contact measuring device, from the viewpoint of general machining accuracy in machining, a relatively rough gear surface is irradiated with laser light obliquely as object light, and sufficient Specular reflection light is obtained. The obliquely projected laser beam has an effective wavelength that is longer by one cosine of the incident angle (COS).
This means that the observation is performed with light having a long wavelength, which is advantageous for the measurement of the rough tooth surface. According to the measuring method using this measuring device, the entire tooth surface of the gear can be directly measured.

[0005]

However, in the case where the tooth surface has a curved surface shape such as a helical gear, the parallel laser light has a different incident angle in each portion. In order to analyze the shape error of the tooth surface, there is a problem that it is necessary to know exactly which part of the tooth surface is irradiated at the incident angle and how many times.

[0006] Therefore, the object of the present invention is to solve the above-mentioned Patent No. 25
An object of the present invention is to solve the above-mentioned problem by using an optical curved surface shape measuring device as disclosed in Japanese Patent No. 57911, and to enable measurement and analysis of the tooth surface shape of a gear having a curved tooth surface.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned object, the present invention separates coherent light emitted from a light source into reference light and object light, and irradiates the object light onto a target curved surface to illuminate the reference light. The holographic image of the target curved surface is obtained from the reflected light of the object light from the holographic image of the reference tooth surface having the curved surface and the image of the test tooth surface having the same shape as that of the target tooth surface. A method of measuring the tooth flank shape of a gear using a non-contact free-form surface measuring instrument for measuring an error of a tooth flank, wherein a simulation of the image of the theoretical tooth flank of the gear having the above-described reference tooth flank and the test tooth flank by ray tracing. The data of the incident angle of the object light at each point on the test tooth surface is collected from the image of the theoretical tooth surface by the method, and the reference tooth surface and a part of the reference tooth surface which are notched are collected. Each of the reference tooth surfaces 2 and 3 was irradiated with the object light. The coordinate origin of the tooth surface image of the reference tooth surface is determined by superimposing the surface images, and the hologram image of the reference tooth surface whose coordinate origin has been determined and the image of the tooth surface to be inspected are superimposed to transfer the coordinate origin. The obtained holographic interference image is obtained, and by superimposing the hologram interference image and the simulation image of the theoretical tooth surface, the correspondence between the incident angle of the object light and the phase of the interference fringe for each point based on the coordinate origin is obtained. Data is collected, and a dimensional error between the reference tooth flank in the normal direction at each point of the test tooth flank is calculated from the data of the incident angle and the data of the phase. It is an object of the present invention to provide a tooth shape measuring method using a non-contact free-form surface measuring instrument for measuring a tooth surface shape error of a tooth surface. Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.

[0008]

FIG. 1 is a mechanical diagram showing an entire configuration of a non-contact free-form surface measuring device used for carrying out a tooth surface shape measuring method according to the present invention, and FIG. It is a side view illustrating the relationship between the surface and the object light incident thereon,
FIG. 3B is a partial plan view taken along line 2-2 of FIG.
FIG. 4 is an explanatory diagram showing a synthetic relationship between a simulation tooth surface, a gear reference tooth surface, and a test tooth surface of a gear by a computer. FIG. 4 shows details of a tooth surface shape forming an example of the reference tooth surface B. FIG. 5 is a partial perspective view, and FIG. 5 is an analysis diagram illustrating the relationship between the optical path difference of the object light incident on the twisted tooth surface and the tooth surface error.

In describing the measuring method according to the present invention, the above-mentioned prior application (Japanese Patent Laid-Open No.
1) Non-contact type optical shape measuring device
This will be described with reference to FIG.

As shown in FIG. 1, the apparatus uses a laser light source 1 and a laser light emitted from the laser light source 1 as a reference laser light R (hereinafter simply referred to as reference light R) and a measurement laser light S (hereinafter referred to as object light). S), the reflecting mirrors 3 and 4 for reflecting the reference light R and the object light S, and the reflecting mirror 3
, Irradiates the reflecting mirror 4, the tooth surface 6a of the measured gear 6, and receives the object light arriving after the reflection, the support shaft device 7 for the measured gear 6, Formed by including a camera 8 and the like for photographing a hologram 6b of the tooth surface 6a formed on the light receiving surface 5 by interference between the reference light R arriving at the light receiving surface 5 and the object light S reflected by the test tooth surface 6a. Have been. As described above, the object light S is applied to the tooth surface 6a to be inspected at a large incident angle, thereby obtaining an advantage that specularly reflected light increases due to a scene phenomenon.

The hologram 6b of the tooth surface 6a to be inspected formed on the light receiving surface 5 is imaged by a camera 8, and the image data is stored by a frame memory 10 and transmitted from a personal computer or a microcomputer via an interface 11. Computer device 1
2 (hereinafter referred to as MPU 12 for simplicity) and is displayed on the screen of the CRT 13 as necessary. Therefore, the MPU 12 has the servo motor 9a
Is the driving source, and the hologram data of the tooth surface in a form corresponding to the position data of each tooth surface to be measured of the gear indexed to the measurement position by being rotationally driven by the servo driving device 9 having the gear indexing encoder 9b Are input one after another.

When measuring the tooth surface shape with the object light S, the gear set on the support shaft device 7 of the measuring machine, that is,
Each tooth surface of a reference gear or a test gear 6 to be described later is irradiated with the same object light S. If the gear 6 is a curved surface having a twist angle like a helical gear, the incident angle of the object light also increases. According to the gear specification of the gear 6 to be tested, the torsion angle β on the pitch circle (diameter D ₀ )
It is set so as to have a predetermined large incident angle with respect to the normal to _zero . That is, as shown in FIGS. 2 and 3, in the specification of the gear having the pitch circle diameter D ₀ , the torsion angle β ₀ on the pitch circle, the incident angle θ, and the rotation angle τ from the center of the tooth surface to the measurement point are measured. These are the above parameters. The setting of the incident angle θ of the object light S is described in JP-A-1-116430 with reference to FIG. 15, which means that the coordinate system of the measuring apparatus shown in FIG. Servo drive device 9 using motor 9a as a drive source and mirror 4 not shown
Irradiating the tooth surface 6a with the servo device for angle adjustment, etc., at this time, the above-described pitch circle diameter D ₀ of the test gear, the torsion angle β ₀ on the pitch circle, The gear introduction such as the angle θ and the rotation angle τ from the center of the tooth surface to the measurement point is input and stored, so when a test gear having the same gear specification is set on the measuring device, By calling the gear specifications from the computer, the servo drive 9 is automatically operated and automatically set to the optimum irradiation position.

In order to measure the tooth surface shape of an example of a gear that is curved by having a torsion angle by the optical curved surface shape measuring device having the above-described configuration, the tooth surface is an involute helicoid curved surface. Therefore, when such a tooth surface is irradiated with parallel object light, the incident angle is slightly different in each part on the surface according to the curvature of the surface. Therefore, the tooth surface hologram formed on the light receiving surface 5 becomes a regular reflection image including the difference in the incident angle. As described above, the hologram 6b of the twisted tooth surface 6a formed on the light receiving surface 5 is imaged by the camera 8, and the imaged data is stored in the frame memory 10 and input to the MPU 12 via the interface 11, and , CRT13
Can also be displayed on the screen. Therefore, the hologram data of the twisted tooth surface is sequentially input to the MPU 12 in a form corresponding to the position data of each tooth surface of the gear by the servo driving device 9.

Now, in order to measure the tooth surface shape of each tooth surface of the test gear 6, first, a reference gear having a reference torsional tooth surface corresponding to the test gear has the hologram 6b as described above. Shooting is performed by the camera 8 under the command of the MPU 12. Next, measurement of each tooth surface 6a of the test gear 6 is started.
That is, the reference gear having the reference tooth surface is replaced by the test gear 6 having a large number of test tooth surfaces and attached to the curved surface measuring device. With respect to one tooth surface of the gear to be inspected, a hologram of the tooth surface to be inspected is obtained on the light receiving surface 5 in the same manner as described above.
Then, an interference fringe is obtained by superimposing the reflected image of the test tooth surface on the hologram 6a of the reference tooth surface by using a servo device such as the servo driving device 9 so as to match. In this case, the superimposing standard and method are described in Japanese Patent Publication No. 2-170 of the present applicant.
As disclosed in Japanese Patent No. 44, the rotation angle position of the test tooth surface at which the first-order diffracted light generated at the time of interference between the two hologram images is maximized.

Next, one wavelength of the reference light R is adjusted by a well-known fringe scanning method, that is, by slightly moving the reflection mirror 3 of the reference light R using an actuator such as a piezo element 3a. Equally divided, the interference fringes generated above are subdivided, data indicating the relationship between the equally divided wavelengths and the interference fringes is taken into the MPU 12, and each point of the interference fringes is calculated by using a method of calculating based on the data. Is calculated and calculated, and contour lines are obtained by image processing of interference fringes. The shape error of the twisted tooth surface 6a is obtained based on the interference fringes composed of the contour lines obtained in this manner. For that purpose, the phase and the incident angle of the interference fringes at each measurement point of the interference fringes due to the holographic interference are obtained. Calculate the shape error of the tooth surface.

At this time, the test tooth surface 6a irradiated with the object light S
As described above, the value of the incident angle θ ° at each point of the tooth surface 6a
Are different values because of the shape of the twisted surface, and thus the effective wavelength at each point changes. When the effective wavelength changes,
Both the pitch and the position of the interference fringes change. In addition, since the actual tooth surface 6a to be inspected is subjected to processing such as chamfering, a regular reflection image of the tooth surface 6a to be inspected is obtained on the CRT 13, and each point of the image is obtained. It is extremely difficult to compare the coordinate position with the data of the phase and the incident angle of the interference fringes. Therefore, the present invention executes a measuring method described in detail below in measuring a tooth surface having a curved surface, for example, a twisted tooth surface shape as described above.

That is, first, the shape of the image captured by the camera 8 is determined based on the ray tracing method known from the gear specifications.
By making full use of 12 and calculating as a simulated image, the simulated image is used to execute an actual measurement calculation of the tooth surface shape of the test tooth surface 6a. Next, the hologram relating to the reference tooth surface A of the reference gear has already been photographed by the camera 8 as described above, and the MPU 1
2, the data of each axis γ, τ, θ, etc. of the photographing position of the reference gear supported by the support shaft device 7 of the optical free-form surface measuring device are transmitted to the interface 11 from the measuring device. Take out from the MPU 12 via the

Next, referring to FIG. 4 together with FIG. 1, for example, a second special gear formed by cutting out a part of another tooth portion of the reference gear 6 having the reference tooth surface A is formed. Using the gauge function of the reference tooth surface B, the servo mechanism 9
By rotating the reference gear 6 at a low speed, the regular reflection image 15 of the second reference tooth surface B is matched with the photographed hologram 14 of the reference tooth surface A on the data in the MPU 12, and the CRT 13 A reference point or a reference line between the reference tooth surface A and the reference tooth surface B is determined as a coordinate image 16 on the screen of the CRT 13 by a regular reflection image on the screen. That is, since the mechanical dimension data of the notch portion of the second reference tooth surface B is obtained in advance as an actual measurement value, the notch portion whose mechanical dimension data is known is the notch portion of the screen of the CRT 13. Since the image is displayed as an image, the coordinates of the image of the reference tooth surface A on the screen of the CRT 13 can be defined from the coordinate image 16 if the points and lines in the image of the cutout portion are set as reference points or reference lines. It becomes. As described above, the two images are matched at the position where the first-order diffracted light of the hologram image in the MPU 12 is maximized.

Next, the measured gear 17 to be measured is attached to the support shaft device 7 of the measuring device in place of the reference gear 6,
A holographic interference fringe 20 is obtained between the regular reflection image 18 and the coordinate image 16 which is a hologram of the reference tooth surface A.
At this time, the reflecting mirror 3 is moved n times the wavelength λ of the reference light R by λ / n by the fringe scanning method described above.
The interference fringes are moved, and data is taken into the MPU 12 each time. Then, when the arithmetic processing of the interference fringes is performed by applying the Fourier analysis method or the like, one pitch of the interference fringes is interpolated,
The height of the fringe at the measurement point can be calculated from the two data of the phase and the movement direction of each point.

On the other hand, a theoretical tooth surface is simulated from the data of each axis of the measuring device described above, and a simulation image 19 is obtained. Then, in advance, the theoretical position of each point of the tooth surface projected on the CRT 13 and its incident angle are calculated,
The image is superimposed on the image of the holographic interference fringe 20 on the CRT 13. After the measurement in this manner, the coordinates of the curved tooth surface in the simulation described above are returned to a plane, and the positions of the tooth surface and the errors of the points are successively connected in a grid to obtain a contour line indicated by 21. is there.

If the above-described measurement and calculation processes are sequentially performed on a plurality of test tooth surfaces of the measurement gear 17, the tooth surface shape of each of the test tooth surfaces having the plurality of curved tooth surfaces can be determined. Can be measured. The above-described sequential measurement process is described in the flowcharts shown in FIGS. 7 and 8 (FIG. 6 is a combined diagram).

When actually measuring a plurality of curved tooth surfaces, the position where the first-order diffracted light becomes maximum is set as the measurement start point, and the spindle indexing position at this time is set as the first start point of the measurement. By doing so, the angular position of the axis of the support device 7 of the measuring device can be determined by accurate indexing for each tooth surface 6a. To summarize the above, since the image of the simulation described above has information on the angle of incidence, and the hologram on the screen of the measured CRT 13 has information on the phase, it is necessary to match these using a special reference plane. As described above, it is necessary to simulate the tooth flank in measuring the tooth flank of the gear at each point as described above, but the parameters which are the basis of this calculation are shown in FIG. In addition to such gear specifications, there is an irradiation position relationship of the object light S.

When a gear such as a reference gear or a test gear is mounted on the measuring device as shown in FIG. 1, the center of the groove of the gear rotates by τ with respect to the center line of the measuring device,
In the state illustrated in FIG. 2, the center of the object light S is emitted offset by the distance value s. There is an appropriate irradiation position depending on the gear specifications, and as a database in advance,
File it.

The incident angle θ of the laser light as the coherent light is
Since it is fixed by the deflection prism of the tooth surface shape measuring device and is exchangeable, it is necessary to input what specification of the deflection prism to use before measurement. When the object light S having the wavelength λ is incident on the tooth surface at a large incident angle θ, the effective wavelength λ ′ is defined by the following equation.

Λ ′ = λ / cos θ For example, in the case of a helical gear, the tooth surface is an involute helicoid. In order to analyze the obtained interference fringes (actually, the phase φ of each point), the effective wavelength λ ′ is calculated from each incident θ ′ for each point, and the step in the normal direction of the surface is calculated from the phase φ of the point, That is, the shape error δ is calculated. At this time, the surface error (step difference) δ has a relation of Δ = 2δ · cos θ with the optical path difference Δ between the _two incident light paths L ₁ and L ₂ in FIG.

Here, the relationship between the phase φ ′ of each point of the interference fringe calculated by the above-described fringe scanning method and the optical path difference Δ is as follows. It is. Therefore, from the above equations, the error δ ′ at each point is
Is It is.

In the above description, the reference plane B in FIG. 3 is cut on the pitch circle in the radial direction and 1/2 in the tooth width direction as shown in FIG. Reference tooth surface B
Is used to determine the coordinate origin of the reference tooth flank A, so the cut dimension is not limited to the above 1/2,
It goes without saying that a step shape such as 1/3, 1/4 or the like may be formed in the tooth width direction.

Further, since the actual machined surface of the gear is not always subjected to precise chamfering, there is considerable variation. Therefore, if the method of the present invention is applied,
Accurate coordinate values of each point can be obtained even for the tooth surface shape having such variations.

[0029]

As is apparent from the above description of the embodiment, according to the present invention, a tooth surface which has conventionally been regarded as only an error with respect to one line on the surface of a tooth surface having a three-dimensional shape is described. Since the shape measurement data is measured as a non-contact and dense surface using the wavelength of the coherent light composed of laser light as a measurement unit, it is possible to grasp the actual shape of the tooth surface. In addition, recently, by introducing a computer with a remarkable increase in computation speed, data is stored and managed, and a database is created. Mechanical control of measurement positions, data acquisition, analysis, display by image analysis, etc. are performed. It also has the effect that it becomes possible.

Further, as described above, the progress of the measurement from the line to the surface has recently provided extremely effective data for the design and machining of gears, which are required to have submicron accuracy, and the quality of gear products has been improved. It can greatly contribute to improvement.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a shape measuring device used for measuring a tooth surface shape error according to the present invention.

FIG. 2A is a side view illustrating the relationship between a test tooth surface of a gear and object light incident thereon, and FIG. 2B is a partial plan view taken along line 2-2 in FIG. is there.

FIG. 3 is a computer simulation tooth surface,
FIG. 4 is an explanatory diagram showing a synthetic relationship between a reference tooth surface of a gear and a test tooth surface of a gear.

FIG. 4 is a partial perspective view showing details of a shape of a reference tooth surface B.

FIG. 5 is an analysis diagram illustrating a relationship between an optical path difference of object light incident on a twisted tooth surface as an example of a tooth surface having a curved surface shape and a tooth surface error.

FIG. 6 is a combined diagram of FIGS. 7 and 8;

7 is a first half of a flowchart of a measurement process shown in FIG. 3;

FIG. 8 is a latter half of the flowchart of the measurement process shown in FIG. 3;

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 ... Laser beam source, 2 ... Beam splitter, 3 ... Reflection mirror, 3a ... Piezo element, 4 ... Reflection mirror, 5 ... Light receiving surface, 6 ... Gear to be examined, 6a ... Tooth surface to be examined, 7 ... Support shaft device Reference numeral 8: Camera, 9: Servo drive, 10: Frame memory, 12: MPU, 13: CRT, 17: Gear to be tested.

Continuation of the front page (72) Inventor Yoshiaki Saito 14-17, Hanazono Higashi-cho, Higashiosaka-shi, Osaka (56) References JP-A-62-172208 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 11/00-11/30

Claims (1)

(57) [Claims] 1. A hologram image of a target curved surface is separated from reference light and reflected light of an object light by separating coherent light emitted from a light source into reference light and object light, and irradiating the object light to a target curved surface. Non-contact free-form surface measurement for measuring the tooth surface shape error of the latter tooth surface with respect to the former tooth surface by holographic interference from the hologram image of the test tooth surface having the same shape as the reference tooth surface having the curved surface In a method of measuring the tooth surface shape of a gear using the device, an image of a theoretical tooth surface of the gear having the reference tooth surface and the test tooth surface is obtained by a simulation method by ray tracing,
Data of the incident angle of the object light at each point on the test tooth surface is collected from the image of the theoretical tooth surface, and the reference tooth surface and a second reference tooth surface in which a part of the reference tooth surface is cut out The coordinate origin of the tooth surface image of the reference tooth surface is determined by superimposing the respective tooth surface images irradiated with the object light at the same time. By superimposing the images to obtain a holographic interference image in which the coordinate origin is shifted, by superimposing the holographic interference image and the simulation image of the theoretical tooth surface, the object light for each point based on the coordinate origin The corresponding data of the incident angle and the phase of the interference fringes are collected, and the dimensional error between the reference tooth flank in the normal direction at each point of the test tooth flank from the data of the incident angle and the phase data Calculate, and test A tooth surface shape measuring method using a non-contact free-form surface measuring device, wherein a tooth surface shape error of a tooth surface is measured.