JP2844727B2 - Inspection method for gear teeth - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for accurately inspecting the tooth contact state of a pair of gears to be meshed in order to make the tooth contact of the gears to be meshed properly.

(Prior Art) As a conventional method for inspecting a gear tooth contact, there is, for example, a method described in JP-A-60-82905.

In this conventional method, the peeling state or the transfer state of the paint applied to the tooth surface of one of the pair of gears meshing after the meshing drive is imaged by a video camera or the like, and the obtained image is subjected to image processing to perform predetermined processing. Are evaluated, and the tooth contact state is inspected based on the evaluation parameters, that is, the quality of the tooth contact and the quality grade are determined.

(Problems to be Solved by the Invention) However, in such a conventional tooth contact inspection method, it is necessary to use, for example, a viscous glow melon as a paint so that only a contact portion is peeled off on a tooth surface. Since Dan has little oil as a lubricant, if the gear is driven to rotate under conditions other than low rotation speed and low torque, it will seize on the tooth surface, so only check the gear contact state at low rotation speed and low torque drive. I couldn't do that. In addition, this inspection method uses the difference in shading in an image to determine the boundary between the portion of the gear tooth surface where paint is applied (or transferred portion) and the portion where the paint is peeled (or not applied). In order to obtain this difference in shading, it is necessary to specify the paint application technique on the tooth surface, the type of Komyotan, and the irradiation angle of the lighting device on the tooth surface. There was also a problem that it took time.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problem by obtaining a degree of contact between screens and a graphic corresponding to a tooth contact from an infrared image of a tooth surface during meshing driving.

(Means for Solving the Problems) For this purpose, the gear tooth contact inspection method of the present invention comprises:
An image of the tooth surface of one of the gears meshing with the other gear during meshing driving is captured by an infrared camera, isotherms at predetermined intervals are obtained from the obtained infrared image, and a temperature gradient is obtained from the obtained isotherm. It is characterized by inspecting the tooth contact state of the pair of gears based on the obtained temperature gradient, and furthermore, an image related to the tooth surface of one of the gears at the time of meshing driving of the pair of gears meshing with each other. An image is taken by an infrared camera, the obtained infrared image is binarized by a predetermined threshold value, a figure corresponding to tooth contact is obtained, and the tooth contact state of the pair of gears is inspected based on the obtained figure. Things.

(Operation) According to the first method of the present invention, while driving a pair of gears to mesh with each other, the tooth surface of one of the gears selected as the inspection target is imaged by an infrared camera, and the obtained infrared image is obtained. A more isotherm is obtained (this isotherm is obtained from a curve connecting points of equal brightness in the infrared image so that the temperature interval becomes a predetermined value, that is, an isotherm line),
From this isotherm, a temperature gradient is obtained, for example, by finding the distance between the isotherms on a line segment having an arbitrary inclination passing through the center of gravity of the figure having the contour of the hottest isotherm. At this time, as the temperature gradient becomes steeper, the tooth contact strength also increases, so that it is possible to accurately grasp a part having a problem in terms of strength in which tooth contact with an excessive strength occurs on the tooth surface. .

According to the second method of the present invention, a figure corresponding to tooth contact can be obtained by binarizing the infrared image with an appropriate threshold value. Inspection of the tooth contact state can be performed.

By the way, each of the above methods eliminates the need for a paint to be applied to the tooth surface and a lighting device for the tooth surface, thereby reducing the cost of the inspection system and shortening the inspection time. By rotating the pair of gears under conditions other than low rotation speed and low torque, it is possible to perform a tooth contact inspection in a state closer to the actual use situation.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram illustrating the configuration of a tooth contact inspection system used for carrying out the methods of the first and second embodiments of the present invention. In the drawing, reference numeral 10 denotes a gear to be evaluated, and in this example, a hypoid is used. Gears are used. In this case, since the gear 10 that is driven to mesh with the gear 11 coupled to the driving device 12 of the pair of meshed gears 10 and 11 is to be evaluated, the tooth contact inspection is performed during the meshing drive, that is, simultaneously with the meshing drive. This eliminates the need for a meshing drive operation for peeling and adhering paint on the tooth surface, which is useful for tooth contact inspection as in the conventional example.

The gear 10 is rotatably positioned and mounted on a work rotating table 13, and is driven by a driving device 12 (for example, a motor) by a control device described later to be meshed when the gear 11 coupled to the rotation shaft rotates. The rotation angle at that time is detected by a rotation angle detection device 14 incorporated in the work rotation table 13.

The tooth surface 10a of the gear 10 is imaged by the infrared camera 15. The infrared camera 15 includes an imaging element 15a, an electronic shutter control circuit 15b, a charge readout circuit 15c, and the like. The electronic shutter control circuit 15b operates based on a command from an image input timing control circuit 16a of the control device 16. Thereby, the image pickup device 15a has a predetermined timing, that is, the work rotation table 13, which is detected by the rotation angle detection device 14,
As a result, each tooth surface 10a of the gear 10 is synchronized with the rotation angle of the gear 10.
(The imaging speed increases as the rotation speed increases), and the charge readout circuit 15c converts the image signal into an A / D converter of the image processing circuit 17.
Enter in 17a. Although one infrared camera 15 may be used, it is more preferable to arrange two infrared cameras 15 at a predetermined angle at which the tooth surfaces can be simultaneously imaged from the drive side and the coast side.

The image processing device 17 includes a first image memory 17b, a second image memory 17c, a CPU 17d, and the like, in addition to the A / D converter 17a. The above elements 17a to 17d are connected by a common bus. ing. The image processing device 17 is connected to the control device 16, and the control device 16
Further, an operation display panel 18 for performing a manual operation such as setting of a corresponding vehicle type of a gear, a start of measurement, and a display of a determination result is connected.

The control device 16 executes the control program shown in FIG. 2 based on the input information from the rotation angle detecting device 14, the image processing device 17 and the operation display panel 18 to control the entire system, and the image processing device 17 is a television camera. The control program shown in FIGS. 3 and 4 is executed based on input information from the control unit 15 and the control unit 16 to perform image processing of the tooth surface image.

That is, first, the system is started in step 101 of FIG. 2, the automatic operation mode is selected in step 102, and the model of the gear corresponding to the work is set in step 103. by). In the next step 104, it is determined whether or not the work is seated (this determination is made, for example, by a seating sensor (not shown) provided on the work turntable 13). If the work is not seated, the control returns to step 102, and the work is seated. If it becomes possible to engage the gears 10 and 11 in step 105,
Indicates the judgment result indicator ("OK" provided on the operation display panel 18,
The two display lamps of “NG” are reset to reset the display of the result of the judgment of the previous work.
The gears 10 and 11 are driven to mesh with each other.

In the next step 107, an image processing start command is issued, for example, by operating the operation panel 18, and in step 108, image processing of the tooth surface image is performed by a subroutine of FIG. 3 and FIG. When the image processing of all the tooth surfaces of the gear 10 is completed in this way and the determination in Step 109 is Yes, the determination result signal (this is transmitted from the image processing device 17) is determined in Step 110. . If there is no discrimination result signal (for example, if there is a transmission error),
Returning to 107, the image processing is performed again, and if an OK signal is received, the "OK" determination result indicator on the operation display panel 18 is turned on in step 111, and if an NG signal or a determination error signal is received, "NG" is determined in step 112. Turn on the judgment result indicator. In this case, the display is reset in step 113 (for example, the operator resets the display by operating the operation display panel 18 after confirming the display). If the reset operation is not performed, the step 114 is performed while the workpiece is seated. When the work is removed from the work turntable 13, an alarm is output in step 115. This alarm is reset in step 117 after resetting the NG and determination error signal in step 116.

Next, image processing will be described with reference to FIGS. 3 and 4. FIG. First, in step 131 of FIG. 3 showing the image processing of the first embodiment of the method of the present invention, an image of the tooth surface at the time of meshing driving of the gear 10 is taken by the infrared camera 15. Note that this imaging is performed by operating the image sensor 15a and the electronic shutter control circuit 15b of the infrared camera 15 based on a command from the control device 16 to which the rotation angle of the gear 10 detected by the rotation angle detection device 14 is input. The imaging speed also increases and decreases in synchronization with the increase and decrease in the rotational speed of the meshing drive.

Next, in step 132, the obtained infrared image is smoothed, and in step 133, isotherms at predetermined temperature intervals are obtained from the smoothed infrared image. Here, this isotherm shows a different shape between the drive side and the coast side as shown in FIGS. 5 (a) and 5 (b), for example, and the predetermined temperature interval is set to an arbitrary value. Can be. In addition, this isotherm is obtained when the isoluminance line, that is, the color boundary line (an example of which is shown in FIG. 6 (a)) is obtained in the infrared image. The linearity of brightness and temperature in an infrared image indicates that the heat generated by friction is high and the temperature becomes high and close to white, and the portion where the gears are in weak contact makes the heat generated by friction low and low and close to black. (The isotherm obtained on the same tooth surface is the sixth
FIG. (B) shows an example, which is in good agreement with FIG. (A)).

In the next step 134, a temperature gradient is obtained from the obtained isotherm. Assuming that the above-mentioned isotherms are, for example, those shown in FIG. 7, the center of gravity G of the figure having the contour of the isotherm T having the highest temperature is first obtained, and then the arbitrary gradient passing through the center of gravity G is obtained. A straight line L is drawn on the screen to determine intersections between the straight line L and the respective isotherms, and distances a, b, c 間 の between the respective isotherms on the straight line L are determined from the respective intersections, and the obtained isothermal lines are obtained. It is determined by dividing the predetermined temperature interval by the distance between the lines.

Based on the temperature gradient determined as described above,
The tooth contact is evaluated at 135. In the evaluation of the tooth contact, the greater the temperature gradient is, the more the excessive force is applied to the relevant portion of the gear, which causes a problem in strength. For example, a temperature gradient exceeding a predetermined value (reference value) is applied to the gear. If there is a part, it is done by evaluating it as NG. In the evaluation of the tooth contact, if a plurality of straight lines passing through the center of gravity G are used, the accuracy of the evaluation can be further improved.

By the way, the method of the first embodiment eliminates the need for a paint to be applied to the tooth surface and a lighting device for the tooth surface, thereby reducing the cost of the inspection system and shortening the inspection time.
Further, since the paint is not applied to the tooth surface, it is possible to rotate the pair of gears that mesh with each other under conditions other than the low rotation speed and the low torque, and perform the tooth contact inspection in a state closer to the actual use condition.

Next, the image processing of the second embodiment of the method of the present invention will be described with reference to FIG. 4. First, in steps 141 and 142, as in steps 131 and 132 of the first embodiment, a tooth surface image is captured by an infrared camera and the obtained infrared image is obtained. Smoothing is performed, and in the next step 143, the smoothed infrared image is binarized. In this binarization, a conventional tooth contact inspection method (for example, a paint is applied to the tooth surface of one of a pair of gears to be meshed, and the peeling state after the meshing drive on the tooth surface selected as the inspection object of the paint). Alternatively, the transfer state is imaged by a video camera or the like (an imaging device other than an infrared camera), the obtained image is binarized, a figure corresponding to tooth contact is obtained, and the tooth contact is evaluated based on the figure). It is assumed that an appropriate threshold is used such that a figure corresponding to substantially the same tooth contact is obtained.

Based on the figure corresponding to this tooth contact, the next step 14
The evaluation of tooth contact is performed in 4. In the evaluation of the tooth contact, the figure corresponding to the tooth contact obtained by the above-described conventional method and the figure corresponding to the tooth contact obtained by the method of this embodiment are almost the same. The lighter and the stronger the tooth contact, the more the part where the paint peels off becomes more intense and becomes closer to white due to the exposure of the metal surface, and the more the gears are in weak contact, the less paint peels off and becomes closer to the paint color. Since this relationship corresponds to the relationship between the brightness and the temperature of the method of this embodiment, for example, the evaluation method of the above-described conventional method may be used as it is, or the evaluation method described in JIS B 1741 may be used.

Accordingly, the method of the second embodiment can obtain the same operation and effect as the method of the first embodiment.

(Effect of the Invention) As described above, the gear tooth contact inspection method of the present invention obtains the degree of contact between the tooth surfaces and a figure corresponding to the tooth contact from the infrared image of the tooth surface during the meshing drive, as described above. A paint to be applied to the tooth surface and a lighting device for the tooth surface are not required, so that the cost of the inspection system can be reduced and the inspection time can be shortened. By rotating and driving under conditions other than the rotational speed and low torque, it is possible to perform a tooth contact inspection in a state closer to the actual use situation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a tooth contact inspection system used for carrying out the methods of the first and second embodiments of the present invention, FIG. 2 is a flowchart showing a control program of a control device in the example, FIG. And FIG. 4 is a flowchart showing a control program of the image processing apparatus in the first and second embodiments, respectively. FIGS. 5 (a) and (b) are diagrams illustrating isotherms in the first embodiment, and FIG. FIGS. 7A and 7B are diagrams showing color boundary lines and isotherms in the same example, respectively, and FIG. 7 is a diagram for explaining how to obtain a temperature gradient in the example. 10 ... gear, 10a ... tooth surface 12 ... drive device, 14 ... rotation angle detection device 15 ... infrared camera, 16 ... control device 17 ... image processing device, 18 ... operation display panel

──────────────────────────────────────────────────の Continued on the front page (56) Reference Dale F. See Mellon, Ind. Thermal thermography, Advanced Materials & Progress, 1988, vol. 134, no. 3, p. 110, 112-114 (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 25/00-25/72 G01M 13/00-13/04 G01M 19/00-19/02 JICST file (JOIS)

Claims (2)

(57) [Claims] An image of a tooth surface of one of the gears meshing with one of the gears at the time of meshing driving is taken by an infrared camera, and isotherms at predetermined intervals are obtained from the obtained infrared image. A method for determining a tooth contact of the pair of gears based on a temperature gradient obtained from the line, and checking a tooth contact state of the pair of gears based on the obtained temperature gradient. 2. An image of a tooth surface of a pair of gears meshing with each other at the time of meshing driving is picked up by an infrared camera, and the obtained infrared image is binarized from a predetermined threshold value to obtain a figure corresponding to a tooth contact. And checking the tooth contact state of the pair of gears based on the obtained graphic.