JP2587765B2 - Method and apparatus for measuring dimensions of mechanical parts - 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 and an apparatus for measuring dimensions of cylindrical mechanical parts such as gears, bearings and bushes.

[0002]

2. Description of the Related Art Dimensional measurement of cylindrical mechanical parts such as gears, bearings, and bushes, such as inner diameter measurement or outer diameter measurement, is performed by air micros, electric micros, etc. in a shipping inspection by a manufacturer that is a manufacturer. In many cases, automatic measurement is performed by the instrument. However, when a user performs a dimensional inspection on these mechanical parts before use, they are mostly measured manually with a micrometer or the like.

[0003] This is because a large number of products having the same dimensions flow in a manufacturer's production line, so that the positional relationship between a measuring instrument such as an air micro or an electric micro and an object to be measured can be optimally arranged. However, when performing dimensional inspection of these machine parts before use, since the dimensions of the machine parts often differ depending on the object to be used,
It is necessary to adjust the position of the measuring instrument every time the measurement is performed, and the trouble is hindering the automation of the measurement. When the user performs dimension measurement using a tool such as a micrometer, the user changes his or her attitude with respect to the workpiece so that the micrometer is perpendicular to the workpiece, and the position between the measuring instrument and the workpiece is changed. The relationship is in an optimal state.

[0004]

In a large-scale factory, for example, a steel mill, long-term maintenance of mechanical equipment is important, and therefore, a large number of maintenance personnel are required.
The measurement of the dimensions of machine parts is also an operation that is always performed at the time of maintenance after disassembly of mechanical equipment, and the frequency of operation is quite high, and automation of dimension measurement in this field has been strongly desired.

In such high-precision dimension measurement, it is necessary to optimize the positional relationship of the measuring device with respect to the measured object. When measuring a dimension with a micrometer or the like, an operator measures the measuring instrument vertically with respect to a measured object to obtain an accurate dimension. Every time a user uses mechanical parts with different sizes and shapes, trying to measure the dimensions automatically requires a lot of effort to position the measuring instrument at the optimum position with respect to the workpiece. . This is the biggest factor that the user has not automated dimensional inspection.

SUMMARY OF THE INVENTION The present invention solves such a problem, and measures dimensions such as inner diameter measurement and outer diameter measurement of cylindrical mechanical parts such as gears, bearings, and bushes, even when the size of an object to be measured is different each time. It is an object of the present invention to provide a method and an apparatus for measuring the dimensions of mechanical parts, which can automatically perform the measurement with high accuracy and without being affected by the gloss of the surface of the object to be measured.

[0007]

According to the method of the present invention, a cylindrical measuring object is set in a measuring area of a three-dimensional measuring machine with its axial direction oriented in a vertical direction. The position in the space and the approximate dimensions are recognized in advance with image information captured from above and in the lateral direction, and the movement path of the probe of the coordinate measuring machine is calculated from the recognized information to calculate the moving path of the probe. A method for measuring the dimensions of a mechanical part that operates, wherein the object to be measured is illuminated from the side opposite to the photographing direction, and the outline of the object to be measured is shaded by blocking the light from the illumination by the object to be measured. It recognizes the position and the approximate dimensions.

Further, the present invention provides a three-dimensional measuring machine in which a cylindrical object to be measured is installed in a measuring area with its axial direction oriented in a vertical direction, and an imaging device for photographing the object from above and from below. Means, an image processing unit for recognizing a position and an approximate size of the measured object in a general space with image information obtained by the imaging unit, and a probe of the CMM from the recognition information obtained by the image processing unit. A dimension measuring device for a mechanical part, comprising: a coordinate measuring machine operation command unit for calculating a movement path, wherein an illuminating means is provided on a side opposite to the photographing means with respect to the object to be measured, and Is photographed by the photographing means.

[0009]

According to the present invention, a cylindrical object to be measured is placed in the measuring area of the coordinate measuring machine with its axial direction oriented in the vertical direction, and the object to be measured is photographed by the photographing means from above and from the side. From the image information, the image processing unit recognizes the position of the measured object in the approximate space and the approximate dimensions, and passes the recognition information to the coordinate measuring machine operation command unit. The coordinate measuring machine operation command unit calculates the movement of the probe of the coordinate measuring machine based on the recognition information, whereby the coordinate measuring machine automatically measures the exact dimensions of the measured object. At that time, the object to be measured is illuminated from the side opposite to the imaging direction by the illuminating means, and a shadow formed by blocking the light by the illumination by the object is illuminated by the imaging means located on the opposite side of the illuminating means with respect to the object Shoot. As a result, it is possible to accurately recognize the position and shape of the measured object without being affected by the gloss of the surface of the measured object, which causes incorrect recognition when trying to recognize the measured object with an image become.

[0010]

FIG. 1 is a schematic view of a dimension measuring apparatus according to an embodiment of the present invention.

[0011] The machine component measurement object 1 includes a gear, a bearing,
It is placed in the measurement area of the coordinate measuring machine 2 by a bush or the like. The shape of the measurement object 1 is basically cylindrical, and the measurement object 1 is placed so that the axial direction faces the vertical direction.

The coordinate measuring machine 2 moves the probe 3 in a three-dimensional space, presses the probe 3 against the object 1,
The three-dimensional position of the point in the space is detected by a high-precision spatial position detecting mechanism, and the accurate dimension of the measured object 1 is measured.

The illumination device 4 and the illumination device 5 are provided in the lateral direction and the downward direction of the measurement object 1, respectively, and the area of the light emitting surface is larger than that of the measurement object 1, and the opposite side of the illumination devices 4 and 5 respectively. When viewed from above, a shadow of the measurement object 1 can be formed. As a light source of the lighting devices 4 and 5, a fluorescent lamp, an incandescent lamp, or the like can be used. In order to reduce uneven brightness, a diffuser plate may be provided on the front surface.

The horizontal television camera 6 and the upward television camera 7 are industrial CCD cameras. The horizontal television camera 6 and the upward television camera 7 each capture an image of a shadow formed by the light from the lighting devices 4 and 5 being blocked by the measurement object 1 and measure the shadow of the measurement object 1. This is for recognizing the approximate position and size of. The image sensors of the television cameras 6 and 7 preferably have as many pixels as possible in order to recognize the object 1 with high accuracy.

Since the measured object 1 is cylindrical, the measured object 1 is placed so that the axial direction is oriented vertically, and the measured object 1 is observed from two directions, that is, the upper direction and the lateral direction. Thereby, it is possible to recognize the position of the measurement object 1 in the approximate space and the approximate dimensions.

The image processing section 8 is for detecting the position, size, etc. of the object 1 photographed by the horizontal television camera 6 and the upward television camera 7 for object recognition.

The coordinate measuring machine operation command unit 9 calculates how to move the probe 3 of the coordinate measuring machine 2 to perform the dimension measurement based on the information on the workpiece 1 detected by the image processing unit 8. , For outputting an operation command to the coordinate measuring machine 2.

In short, the features of this embodiment are as follows.
A cylindrical mechanical component measuring object 1 of unknown dimensions is placed in the measuring area of the coordinate measuring machine 2 with its axial direction oriented vertically, and the measuring object 1 is placed on an upward television camera 7 and a horizontal television camera 6. The image processing unit 8 recognizes the position and approximate dimensions of the measured object 1 in the general space from the image information, and passes the recognized information to the coordinate measuring machine operation command unit 9 to perform tertiary measurement. A method and apparatus for calculating the movement of the probe 3 of the original measuring machine 2 and thereby automatically measuring the accurate dimensions of the workpiece 1 by the coordinate measuring machine 2,
Illumination devices 5 and 4 are provided below and in the lateral direction of the object 1, and shadows formed by blocking the light from the illumination devices 5 and 4 by the object 1 illuminate the illumination devices 5 and 4 with respect to the object 1. By photographing with the upward and lateral cameras 7 and 6 located on the opposite side of the image, the gloss of the surface of the measurement object 1 which causes erroneous recognition when trying to recognize the measurement object 1 as an image, Without being affected by curvature, etc., the position of the workpiece 1
The purpose is to enable accurate recognition of the shape.

FIG. 2 is a view for explaining image processing in this embodiment.

FIG. 2A is an external view of the measured object 1. The approximate position and approximate dimensions of the measurement object 1 are recognized by the image processing unit 8 based on the images captured by the two cameras 6 and 7, and the recognition information is transmitted to the coordinate measuring machine operation command unit 9. hand over.

FIG. 2 (b) shows the image of the object 1 photographed by the television cameras 7 and 6 positioned above and in the lateral direction of the object 1, and each feature amount to be recognized. Here, O is the center of the object 1 in the horizontal plane, R ₁ is the inner diameter of the object 1, R ₂
Is the outer diameter of the body of the object 1, R ₃ is the outer diameter of the collar of the object 1, and is the same as R ₂ when there is no collar. H
₁ is the height of the measured object 1, the height of the H ₂ Watsuba unit.

FIG. 3 is a flow chart for recognizing the measured object 1 by image processing.

First, the object to be measured 1 is photographed by the television cameras 7 and 6 in the upward and lateral directions to obtain a binarized image. next,
The approximate position and approximate dimensions of the object 1 in the space are determined.

From the image taken by the television camera 7 in the upward direction, the inner diameter R _{1 and} the outer diameter R _{3 of the} collar portion can be clearly distinguished from the background. Since the measured object 1 has a cylindrical shape, the center of gravity O of the measured object 1 in the horizontal plane is obtained by calculating the center of gravity.
Can be requested.

Also, from the image taken by the television camera 6 in the horizontal direction, the outer diameter R ₂ of the body of the object 1, the outer diameter R _{3 of} the collar, the height H _{1 of} the object 1, the height H ₂ is required. The distinction between the body part and the brim part may be obtained by finding a point at which the number of pixels in the horizontal direction on the image greatly changes. The outer diameters R ₂ , R ₃ and the heights H ₁ , H ₂ can be obtained by determining the Feret diameter by image processing since the image of the measurement object 1 looks rectangular when viewed from the lateral direction.

When the image of the object 1 can be photographed with good contrast, such image processing can be performed to obtain the approximate position and dimensions of the object 1.
When the measured object 1 has a partial or overall gloss such as an iron product, the measurement is performed by illuminating the measured object 1 with light from the normal indoor or outdoor lighting environment or the cameras 6 and 7. When the object 1 is imaged, the glossy portion 10 becomes a bright image as shown in FIG. 4 due to the gloss of the object 1, and if binarized as it is, the object 1 may be recognized as having a different shape.

When the shape of the measurement object 1 is a mechanical part such as a gear, a bearing or a bush, it is basically cylindrical, so that the illuminating devices 4 and 5 arranged on the opposite sides of the cameras 6 and 7 for capturing images. When the object 6 is illuminated by the camera and the camera 6 and 7 photograph the shadow formed by blocking the light by the object 1, FIG.
An image that clearly shows the characteristics of the measurement object 1 as shown in (b) can be obtained. According to this method, the position and shape of the cylindrical measurement object 1 can be stably recognized.

FIG. 5 is a view showing the movement of the probe 3 of the coordinate measuring machine 2 with respect to the measured object 1 when the inner diameter of the measured object 1 is measured. FIG. 6 is a flowchart for explaining the movement of the probe 3 in the case of measuring the inner diameter. FIG. 7 is a diagram showing the movement of the probe 3 of the coordinate measuring machine 2 with respect to the measured object 1 when the outer diameter of the measured object 1 is measured.

Since the center point O on the plane of the measured object 1 and the approximate inner and outer diameters of the measured object 1 have been determined in advance by image processing, the probe 3 of the CMM 2 uses the information to determine the measured object. Move fast to a position close to the surface of 1, then
The probe position at the moment when it moves at a low speed toward the surface of the measurement object 1 and the pressing pressure when it comes into contact with the measurement object 1 exceeds a certain value is defined as the probe position on the measurement object 1.

The path of the probe 3 of the coordinate measuring machine 2 when measuring the inner diameter of the object 1 will be described with reference to FIGS.

First, the probe 3 moves at a high speed to a point Q ₁ that is vertically above the center point O on the plane of the measurement object 1. next,
At a height h on the vertical center point O to the height direction measurement point Q ₂ moves at high speed. Furthermore, to move in the circumferential direction of the angle θ lies in a direction measured 1 point Q ₃ near the inner surface at a high speed.
Distance between the point Q ₃ and the inner surface of the measuring object 1 is dependent detection accuracy of the inner diameter R ₁ of the center point O and schematic detected by image processing. By the image processing, if it is more accurate detection can take nearly the distance between the point Q ₃ and the inner surface of the measuring object 1. Next, Yuki move to the low speed toward the probe 3 on the inner surface P _i of the measuring object 1, the detected position of the point P _i to the point where pressing force of the probe 3 becomes a constant value to the measured object 1 Measure. The point P _i detected by the same movement of the probe at a plurality of points in the circumferential direction of the measuring object 1, obtains a circle at the height h of the measured object 1 lined their position measurement data by a method such as a least square method And the diameter of the circle as the inner diameter.

Next, the path of the probe 3 of the coordinate measuring machine 2 when measuring the outer diameter of the object 1 will be described with reference to FIG.

The probe 3 moves at a high speed to a point Q ₁ located obliquely above the object 1 with respect to the object 1. Next, moves at high speed to the point Q ₂ to which is in the height h of the downward against the point Q _1. Furthermore, to move the measurement object 1 in the point Q ₃ near the outer surface at a high speed. Next, the probe 3 is slowly moved toward the surface _{Po of the} workpiece 1 in the same manner as in the inner diameter measurement, and a point at which the pressure of the probe 3 on the workpiece 1 reaches a constant value is detected. to measure the position of the P _o. A point _Po is detected at a plurality of points in the circumferential direction of the object 1 by the same probe movement, and their position measurement data are connected by a method such as the least square method to obtain a circle at the height h of the object 1. The diameter of the circle is defined as the outer diameter.

[0034]

As described above, according to the present invention, the dimensional inspection before use of a mechanical part, which had to be manually performed with a tool such as a micrometer in the past, is performed. Even if it is different every time, measurement can be performed automatically, easily and accurately, without being affected by the gloss of the surface of the measurement object, which may cause incorrect recognition when trying to recognize the measurement object with an image. Becomes

[Brief description of the drawings]

FIG. 1 is a schematic view of a dimension measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating image processing according to an embodiment of the present invention.

FIG. 3 is a flowchart of recognition of a measured object by the image processing.

FIG. 4 is a diagram illustrating an example in which a glossy portion of a measurement object is a bright image.

FIG. 5 is a view showing the movement of a probe of a coordinate measuring machine when measuring the inner diameter of a measurement object in the embodiment of the present invention.

FIG. 6 is a flowchart for explaining the movement of a probe in the case of measuring the inner diameter.

FIG. 7 is a view showing the movement of a probe of a coordinate measuring machine when measuring the outer diameter of a measured object in an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measurement object 2 CMM 3 Probe 4 Illumination device 5 Illumination device 6 Horizontal television camera 7 Upward television camera 8 Image processing part 9 CMM operation command part 10 Glossy part

Claims (2)

(57) [Claims] 1. A cylindrical measuring object is installed in a measuring area of a three-dimensional measuring machine with its axial direction oriented in a vertical direction, and the position of the measuring object in a general space and the general dimension are raised. A method for measuring dimensions of a machine component that operates the coordinate measuring machine by recognizing in advance with image information captured from a direction and a lateral direction, calculating a movement path of a probe of the coordinate measuring machine from the identification information, Illuminating the measurement object from a side opposite to a photographing direction, and recognizing an approximate position and an approximate size of the measurement object by a shadow formed by blocking the light by the illumination by the measurement object. The method of measuring the dimensions of the machine parts. 2. A three-dimensional measuring machine in which a cylindrical measurement object is set in a measurement area with its axial direction oriented vertically, and photographing means for photographing the measurement object from above and sideways;
An image processing unit for recognizing a position and a general size of the measurement object in a general space with image information obtained by the photographing unit; and a moving path of the probe of the coordinate measuring machine from the recognition information by the image processing unit. A dimension measuring device for a mechanical part, comprising: a coordinate measuring machine operation command unit for calculating; and an illuminating unit provided on a side opposite to the photographing unit with respect to the measured object, and measuring light from the illuminating unit. An apparatus for measuring the dimensions of mechanical parts, wherein a shadow formed by blocking an object is photographed by the photographing means.