Visual inspection method and visual inspection device

Abstract

The purpose of the present invention is to provide a visual inspection method and a visual inspection device which reduce measurement error caused by the reflection, from adjacent structures, of laser light projected for light-section measurement onto glossy surfaces of densely and regularly arranged objects to be measured.　A visual inspection method according to the present invention, which measures the three-dimensional shape of an object to be measured, in which a plurality of glossy parts to be measured are arranged, through a light section method and detects an abnormality in the shape of the object to be measured. The visual inspection method is characterized by detecting an abnormality in the shape of the object to be measured on the basis of: a captured image obtained by setting a predetermined angular range of the laser light such that the parts to be measured, which are measurement targets, are irradiated with the laser light, and reflection of the laser light from the other parts to be measured to the parts to be measured, which are the measurement targets, is suppressed; and the irradiation position of the laser light.

Description

Appearance inspection method and appearance inspection device

[0001] The present invention relates to an appearance inspection method and an appearance inspection device.

[0002] In an inspection device that measures the three-dimensional shape of a measurement object in which a plurality of measurement parts having gloss are arranged by the optical cutting method and detects an abnormality in the shape of the measurement object, in the inspection of fusion balls such as motor coil ends, it is necessary to accurately inspect abnormalities such as flatness, burrs, protrusions, and craters. That is, a highly accurate and efficient inspection method for fusion balls such as motor coil ends is desired.

[0003] Patent Document 1 discloses a technique for reducing the dead angle of the concave portion shown in FIG. 3 of Patent Document 1, a drive mechanism for inverting an inclined optical cutting sensor 180 degrees in the forward and return paths, and inspecting by relatively moving the optical cutting sensor and the measurement object.

[0004] Japanese Patent Application Laid-Open No. 2020-118650

[0005] However, in the technique described in Patent Document 1, there is a problem that in a plurality of fusion balls such as motor coil ends, reflection of adjacent structures is reflected in the cross-sectional shape of the fusion balls to be measured, resulting in an error.

[0006] An object of the present invention is to provide an appearance inspection method and an appearance inspection device that reduce measurement errors due to reflection of reflected light from adjacent structures of laser light projected for optical cutting measurement on the glossy surface of a measurement object arranged at high density and regularly.

[0007] The appearance inspection method of the present invention is an appearance inspection method for measuring the three-dimensional shape of a measurement object in which a plurality of measurement parts having gloss are arranged by the optical cutting method and detecting an abnormality in the shape of the measurement object, wherein laser light is irradiated onto the measurement part to be measured, and a predetermined angle range of the laser light is set so that reflection of the laser light from the other measurement parts to the measurement part to be measured is suppressed. Based on the obtained captured image and the irradiation position of the laser light, an abnormality in the shape of the measurement object is detected.

[0008] Furthermore, the present invention provides an appearance inspection device that measures the three-dimensional shape of an object to be measured, which has a plurality of glossy parts to be measured arranged therein, by the light section method, and detects abnormalities in the shape of the object to be measured, and is characterized by comprising: a light section sensor that irradiates the parts to be measured with laser light; a control device that sets a predetermined angular range of the laser light so as to suppress the reflection of the laser light from parts to be measured other than the object to be measured to the part to be measured of the object to be measured; and a detection unit that detects abnormalities in the shape of the object to be measured based on an image obtained by imaging the parts to be measured irradiated with the laser light and the irradiation position of the laser light.

[0009] According to the present invention, it is possible to provide a visual inspection method and a visual inspection apparatus that reduce measurement errors caused by reflections from adjacent structures of a laser beam projected for optical section measurement on a glossy surface of an object to be measured that is densely and regularly arranged.

[0010] This is a schematic diagram of the visual inspection apparatus of this embodiment. This is a schematic diagram of the visual inspection apparatus and the object to be measured of this embodiment. This is a schematic diagram of the object to be measured viewed from above. This is a diagram showing the measurement results of the objects to be measured in the comparative example and the embodiment. This shows a flowchart showing an example of measurement using the visual inspection apparatus of this embodiment. This shows a flowchart showing an example of measurement using the visual inspection apparatus of this embodiment. This shows a flowchart showing an example of measurement using the visual inspection apparatus of this embodiment. This shows a flowchart showing an example of measurement using the visual inspection apparatus of this embodiment.

[0011] The embodiments of the present invention will be described below with reference to the drawings. The embodiments are illustrative examples for explaining the present invention, and have been omitted and simplified as appropriate for clarity of explanation. The present invention can also be carried out in various other forms. Unless otherwise specified, each component may be singular or plural.

[0012] The positions, sizes, shapes, and ranges of the components shown in the drawings may not represent their actual positions, sizes, shapes, and ranges in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, and ranges disclosed in the drawings.

[0013] In this example, we will describe an object to be measured that has a high density and regularly arranged glossy surface, such as a motor coil end weld (a coil end with a spherical shape). This technique uses the light section method to reduce measurement errors caused by reflections of adjacent weld structures, in order to detect shape abnormalities that are difficult to detect with image acquisition from above alone.

[0014] The visual inspection apparatus of this embodiment will be explained using Figures 1 and 2. Figure 1 is a schematic diagram of the visual inspection apparatus of this embodiment. Figure 2 is a schematic diagram of the visual inspection apparatus and the object to be measured of this embodiment.

[0015] The visual inspection device mainly consists of a light sectioning sensor 11 that irradiates the object to be measured 18 with laser light 13, and a control device 16.

[0016] The light cutting sensor 11 allows adjustment of the irradiation angle of the laser beam 13 relative to the coil end group 12. By rotating the cutting sensor rotation drive unit 10 according to the rotation drive command of the control device 16, the irradiation angle of the laser beam 13 can be adjusted, and irradiation can be performed at a predetermined inclination angle φ (inclination angle 15). The cross-sectional curved surface of the object to be measured 18, which is the measurement result, is transmitted to the control device 16.

[0017] The control device 16 can control the tilt angle φ by sending a rotation drive command to the cutting sensor rotation drive unit 10 of the light cutting sensor 11. It can also receive the cross-sectional curved surface of the object to be measured 18, which is the measurement result, and perform inspection based on that information. Furthermore, it can send a command to the object to be measured rotation drive unit 17 to rotate the object to be measured 18 in the object rotation direction 14, thereby appropriately performing measurement and inspection of the multiple rows of coil end groups 12. The control device 16 has multiple functions, but separate devices may be provided for each function.

[0018] Furthermore, it includes an image acquisition device that captures an image of the measurement unit irradiated with laser light. It also includes a detection unit that detects abnormalities in the shape of the object being measured based on the captured image and the irradiation position of the laser light. The detection unit may be included in the control device 16.

[0019] In other words, the visual inspection device of this embodiment measures the three-dimensional shape of an object to be measured, which has multiple glossy parts arranged together, using the light section method, and detects any abnormalities in the shape of the object to be measured.

[0020] The system includes a light sectioning sensor that irradiates the part to be measured with laser light, a control device that sets a predetermined angular range of the laser light so as to suppress reflection of the laser light from parts other than the object to be measured to the part of the object to be measured, and a detection unit that detects abnormalities in the shape of the object to be measured based on an image obtained by imaging the part to be measured irradiated with laser light and the irradiation position of the laser light.

[0021] Such an appearance inspection device makes it possible to provide an appearance inspection method and appearance inspection device that reduces measurement errors caused by reflections from adjacent structures of laser light projected for optical section measurement on the glossy surface of an object to be measured, which is arranged at high density and in a regular manner.

[0022] Next, we will explain the measurement results when the inclination angle φ is changed, using Figures 3 and 4. Figure 3 is a schematic diagram of the object being measured as seen from above. Figure 4 shows the measurement results of the objects being measured in the comparative example and the example.

[0023] In Figure 3, the vertical direction is the circumferential direction of the coil end group 12 of the object to be measured 18, and the horizontal direction is the width direction. The first row consists of coil end 1a, coil end 1b, and coil end 1c, the second row consists of coil end 2a, coil end 2b, and coil end 2c, and the third row consists of coil end 3a, coil end 3b, and coil end 3c.

[0024] The axis (tilt angle φ0 to φ4) from which the laser beam 13 is irradiated is shown by a dashed line. For example, if the tilt angle φ0 = 0 degrees is set for coil ends 2a, 2b, and 2c in the second row, when measured, coil ends 2a and 2b will be reflected, resulting in a distorted measurement result as shown in the comparative example in Figure 4. Due to other reflections, accurate shape determination becomes difficult.

[0025] When the inclination angle φ1 = 10 degrees, even if measurement is taken, the vertex of coil end 2b is captured in the image while coil end 2a is being measured, resulting in a distorted measurement result as shown in the comparative example in Figure 4.

[0026] When the tilt angle φ2 = 18 degrees, even during measurement, the vertex of coil end 2b is captured in the image while coil end 2a is being measured. However, the next measurement has not yet started.

[0027] When the inclination angle φ3 = 34 degrees, the top of coil end 1c is reflected in coil end 2a during measurement, but the measurement of coil end 2a is completed.

[0028] When the inclination angle φ4 = 40 degrees, the peak of coil end 1c is reflected in coil end 2a during measurement.

[0029] Therefore, in this embodiment, by setting the inclination angle φ of the laser line in the range of 18 degrees < φ < 34 degrees, reflections from coil ends 2b and 1c do not occur during the measurement of coil end 2a, and measurement can be performed as shown in the embodiment in Figure 4. Note that this value is just an example. With such measurement, an appearance inspection device that detects abnormalities in the shape of an object to be measured can accurately inspect for abnormalities such as flattening, burrs, protrusions, and craters in welded balls such as motor coil ends.

[0030] In this embodiment, the arrangement of the measurement portions of multiple objects to be measured has multiple first direction rows aligned in a first direction (vertical direction in the drawing, circumferential direction of the coil end group 12 of the object to be measured 18) in a plan view, and multiple second direction rows aligned in a second direction different from the first direction (left-right direction in the drawing, width direction of the object to be measured), and the longitudinal direction of the irradiated laser beam extends in a direction different from the first and second directions. In other words, it is inclined.

[0031] By setting the inclination angle φ to a predetermined angular range, accurate inspection is possible without being affected by reflections from other coil ends. The predetermined angular range of the inclination angle φ can be calculated geometrically using the following (Equation 1), provided that the arrangement of the coil ends is regular: φa < φ < φb ... (Equation 1) φa = sin ―１ (Rw / Δx) φb=sin ―１ {Rw / √((2Δx) ２ +Δy ２ )} Here, Rw is the radius of the coil end. Δx is the distance between coil ends in a row, for example, the distance from the center of coil end 1a to the center of coil end 1b. Δy is the distance between rows, for example, the distance from the center of coil end 1a in the first row to the center of coil end 2a in the second row.

[0032] An appropriate tilt angle can be calculated by calculating the angular range of the laser beam in a plan view based on the spacing between the measurement portions of the object being measured in the multiple rows aligned in the first direction and the multiple rows aligned in the second direction, which is different from the first direction. Alternatively, a camera or similar device may be installed, and the spacing between the measurement portions of the object being measured in the first and second directions can be obtained by object detection from the image acquired by the camera, and the angular range of the laser beam in a plan view can be calculated. Furthermore, the angular range can be calculated by simulation or by calculation from coordinates.

[0033] Next, we will explain the flow of the visual inspection method. Figure 5 shows a flowchart of an example of measurement using the visual inspection device of this embodiment.

[0034] The inspection process begins in step S1, where the coordinates of the weld spheres at the coil end are read. In step S2, the optimal tilt angle is calculated. In step S3, the optical section sensor is rotated to the appropriate tilt angle. In step S4, the object to be measured is rotated to sequentially inspect multiple weld spheres. In step S5, point cloud data measured for each weld sphere is created. In step S6, a defect inspection is performed on each weld sphere, and the process is completed.

[0035] When detecting anomalies, the system has a focus area that concentrates on a specific part to be measured, and the reflection of the laser light is suppressed by setting the angle range of the laser light to suppress reflections of adjacent parts to be measured during measurement of the focus area of ​​the specific part to be measured.

[0036] Furthermore, when detecting abnormalities in the shape of the measurement part of the object being measured, by inspecting at least one of the following: the difference in height of the measurement part (coil end) relative to the reference height, the amount of displacement of the measurement part (coil end), and the cross product of the measurement part (coil end), it is possible to control not only the appearance but also the coil end height and molten volume during production, thereby contributing to shortening the overall length of the motor, miniaturization, and improving the reliability of the welded part.

[0037] Let's explain another example of Figure 5. Figure 6 shows a flowchart of an example of measurement using the visual inspection device of this embodiment. Steps S1, S2, S4, S5, and S6 are the same as in Figure 5. Point cloud data is created measured for each weld ball. In step S6, a defect inspection is performed for each weld ball and the process is completed. Instead of step S3 in Figure 5, as step S3-2, the optical section sensor and the object to be measured are moved relative to each other as a means of setting the inclination angle φ. By moving the optical section sensor (laser beam) and the object to be measured relative to each other, an inclination angle can be set. That is, the angle range can be set by rotating the laser beam irradiation device or by moving the laser beam and the object to be measured relative to each other.

[0038] In other words, by detecting abnormalities in the shape of the object being measured based on an image obtained by setting a predetermined angular range in the plan view of the laser beam such that the laser beam in the plan view irradiates the part of the object being measured and the reflection of the laser beam from other parts of the object being measured to the part of the object being measured is suppressed, and based on the irradiation position of the laser beam, it is possible to reduce measurement errors caused by reflections of light from adjacent structures of the laser beam projected for optical section measurement on the glossy surface of an object being measured that is densely and regularly arranged.

[0039] Let's explain another example of Figure 5. Figure 7 shows a flowchart of an example of measurement using the visual inspection device of this embodiment. Steps S1 to S6 are the same as in Figure 5. Before step S1, in step S7, a plan view image is acquired from the camera image. In step S8, the positional spacing of the welded parts of the weld ball is acquired. In step S9, the optimal inclination angle is calculated. Calculating the optimal inclination angle in advance from the plan view image and the positional spacing of the welded parts leads to improved measurement accuracy.

[0040] Let's explain another example of Figure 5. Figure 8 shows a flowchart of an example of measurement using the visual inspection device of this embodiment. Steps S1 to S6 are the same as in Figure 5. Before step S1, in step S10, the number of welding points per revolution of the motor coil and the number of coil end rows are input. In step S10, the optimal inclination angle is calculated. Calculating the optimal inclination angle in advance from the number of welding points and the number of coil end rows leads to improved measurement accuracy.

[0041] Based on the number of points per circumference and the number of rows of coil ends of the coil end welding part, which is the measurement part of the object to be measured, by calculating the angular range of the laser beam in a plan view, the interval between the measured parts can be calculated from the specifications of the motor (the number of coil end welding part points per circumference, the number of rows of coils), thus eliminating manual input.

[0042] As described above, in a glossy surface arranged at high density and regularly, it is possible to reduce the measurement error caused by the reflection of the laser beam projected for optical cutting measurement from the adjacent structure. Also, without the need for an increase in measurement time or an increase in capital investment due to增设 an optical cutting sensor, etc., by preventing reflection, high-precision shape measurement becomes possible. Also, it is possible to detect minute defects such as in the motor coil end welding part, which is minute and has a large number of inspection parts, enabling high efficiency and quality improvement. And it can contribute to preventing the flow of defective products to the subsequent process, improving the throughput of the entire production line, and reducing power consumption due to high-efficiency production.

[0043] 1a... coil end, 1b... coil end, 1c... coil end, 2a... coil end, 2b... coil end, 2c... coil end, 3a... coil end, 3b... coil end, 3c... coil end, 10... cutting sensor rotation drive part, 11... optical cutting sensor, 12... coil end group, 13... laser beam, 14... rotation direction of the object to be measured, 15... tilt angle, 16... control device, 17... rotation drive part of the object to be measured, 18... object to be measured.

Claims

1. An appearance inspection method for detecting abnormalities in the shape of an object, wherein the three-dimensional shape of an object having a plurality of glossy parts arranged therein is measured by the light section method, and the abnormalities in the shape of the object are detected based on an image obtained by setting a predetermined angular range of the laser beam such that the laser beam is irradiated onto the parts of the object to be measured and the reflection of the laser beam from other parts of the object to be measured to the parts of the object to be measured is suppressed, and the irradiation position of the laser beam.

2. The visual inspection method according to claim 1, characterized in that the angle range is set by rotating the laser light irradiation device or by the relative movement of the laser light and the object to be measured.

3. An appearance inspection method according to claim 1, characterized in that the arrangement of the measurement portions of a plurality of objects to be measured comprises a plurality of first direction rows aligned in a first direction and a plurality of second direction rows aligned in a second direction different from the first direction, and the longitudinal direction of the irradiated laser light extends in a direction different from the first direction and the second direction.

4. An appearance inspection method according to claim 1, wherein when detecting an abnormality, the method has a focus area that focuses on a specific part to be measured, and the suppression of reflection of the laser light is an angular range of the laser light that suppresses reflection of adjacent parts to be measured during measurement of the focus area of ​​the specific part to be measured.

5. An appearance inspection method according to claim 3, characterized in that the angular range of the laser beam is calculated based on the spacing between the measurement portions of the object to be measured in a plurality of rows arranged in the first direction and a plurality of rows in the second direction which are different from the first direction.

6. An appearance inspection method according to claim 3, characterized in that the distance between the measurement portion of the object to be measured in the first direction and the second direction is obtained by object detection from an image acquired by a camera, and the angular range of the laser beam is calculated.

7. The visual inspection method according to claim 1, characterized in that the angle range is calculated by simulation or by calculation from coordinates.

8. The visual inspection method according to claim 1, characterized in that the measurement of the object to be measured is performed by measuring the welded portion of a coil end having a spherical shape.

9. An appearance inspection method according to claim 1, characterized in that when detecting an abnormality in the shape of the measurement part of the object to be measured, at least one of the following is inspected: the difference from the reference height of the measurement part, the amount of positional displacement of the measurement part, and the cross product of the measurement part.

10. An appearance inspection method according to claim 3, characterized in that the angular range of the laser beam is calculated based on the number of points per circumference of the coil end weld portion, which is the part of the object to be measured, and the number of rows of coil ends.

11. An appearance inspection device for measuring the three-dimensional shape of an object having a plurality of glossy parts arranged therein by the light section method and detecting abnormalities in the shape of the object, comprising: a light section sensor that irradiates the parts to be measured with laser light; a control device that sets a predetermined angular range of the laser light so as to suppress the reflection of the laser light from parts to be measured other than the object to be measured to the object to be measured; and a detection unit that detects abnormalities in the shape of the object to be measured based on an image obtained by imaging the parts to be measured irradiated with the laser light and the irradiation position of the laser light.

Images