KR102177726B1 - Method and apparatus for inspecting workpiece - Google Patents

Abstract

The present invention relates to a method and an apparatus for inspecting a workpiece, which are able to compare the workpiece to be inspected with a reference workpiece and to determine whether or not there is a defect in the workpiece to be inspected. According to one embodiment of the present invention, the method for inspecting the workpiece comprises: a step of generating a three-dimensional image of a virtual reference workpiece based on a basic specification parameter of the workpiece and a basic specification parameter of a processing tool which processes the workpiece; a step of generating a three-dimensional image of the workpiece to be inspected by using a camera or a line laser; and a first inspection step of comparing the three-dimensional image of the reference workpiece with the three-dimensional image of the workpiece to be inspected, and determining whether or not there is a defect in the workpiece to be inspected.

Description

Processed product inspection apparatus and inspection method {Method and apparatus for inspecting workpiece}

The present invention relates to an apparatus and method for inspecting a processed article, and more particularly, to an apparatus and method for inspecting a processed article for determining whether a surface of a processed article such as a gear is defective using a camera or a laser.

After producing processed products such as gears, vision inspection is mainly used to determine product defects. In this vision inspection, the processed product to be inspected is photographed with a camera and the product defect is determined by comparing the photographed image information with standard image information.

At this time, standard image information is used as a 3D standard image by selecting a processed product with no defects among the produced processed products and photographing it to obtain a 3D image or using a CAD design file as it is.

However, even in the case of an actual processed product without defects, there is a limitation in that precise inspection of the processed product cannot be performed because there is a slight difference or defective element for each processed product, and the CAD design file cannot express the actual processed product as it is.

Patent Document 1: Korean Patent Application Publication No. 2010-0082249 (published on July 16, 2010) Patent Document 2: Korean Patent Application Publication No. 2017-0080910 (published on July 11, 2017) Patent Document 3: Korean Patent Registration No. 10-1816150 (announced on January 30, 2018)

The present invention is to solve the above problem, by using a 3D image generation algorithm of the processed product to generate a three-dimensional reference image of a reference processed product, photographing the processed product to be inspected with a camera or a line laser An object of the present invention is to provide an apparatus and method capable of determining whether or not a processed product is defective by obtaining a three-dimensional image by irradiating with and comparing the obtained reference image with the image of the processed product to be inspected.

According to an embodiment of the present invention, a processed product inspection method for determining whether or not the inspection target processed product is defective by comparing the inspection target processed product with a reference processed product, based on a basic specification parameter of the processed product and a basic specification parameter of a machining tool that processes the processed product. Generating a 3D image of the virtual reference processed product; Generating a three-dimensional image of the workpiece to be inspected using a camera or a line laser; And a first inspection step of comparing the 3D image of the reference processed product with the 3D image of the processed product to be inspected to determine whether the processed product to be inspected is defective.

According to an embodiment of the present invention, there is provided an apparatus for inspecting a processed product that compares a processed product to be inspected with a reference processed product to determine whether the processed product to be inspected is defective, comprising: a support for supporting the processed product to be inspected; A driving motor that rotates the support; A first camera spaced apart from the support by a predetermined distance to photograph a processed product to be inspected; An inspection target processed product image generation unit that generates a three-dimensional image of the inspection target processed product photographed by the first camera; And a first inspection unit that compares the 3D image of the processed product to be inspected with a 3D image of a virtual reference processed product to determine whether there is a defect or not, wherein the 3D image of the reference processed product includes a basic specification parameter of the processed product and the processed product. It provides a workpiece inspection apparatus, characterized in that generated based on the basic specification parameters of the machining tool to be processed.

According to an embodiment of the present invention, a 3D image of a reference processed product is generated using a novel 3D image generation algorithm, and since this reference image represents the actual processed product, it can be used as a reference image when inspecting the processed product. There is an advantage of being able to perform accurate good product determination of processed products.

1 is a diagram illustrating an apparatus and method for inspecting a processed product according to an embodiment of the present invention;
2 is a diagram illustrating an apparatus for inspecting a processed product according to an embodiment;
3 is a view for explaining a workpiece inspection apparatus according to an alternative embodiment;
4 to 6 are diagrams for explaining an exemplary method of generating a three-dimensional image of a workpiece to be inspected using a laser;
7 and 8 are diagrams illustrating an exemplary method of generating a three-dimensional image of a reference workpiece,
9 and 10 are diagrams for explaining a method of converting a three-dimensional image of a reference processed product into a two-dimensional image;
11 and 12 are diagrams illustrating a method of extracting a reference laser image from a three-dimensional image of a reference processed product according to an embodiment;
13 and 14 are diagrams for explaining a method of extracting a reference laser image from a three-dimensional image of a reference processed product according to an alternative embodiment;
Fig. 15 is a block diagram showing an exemplary system configuration for implementing a method for inspecting a workpiece according to an embodiment.

The above objects, other objects, features, and advantages of the present invention will be easily understood through the following preferred embodiments related to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

When a component is referred to as being on another component in the specification, it means that it may be formed directly on the other component or that a third component may be interposed therebetween.

In the present specification, when terms such as first and second are used to describe components, these components should not be limited by these terms. These terms are only used to distinguish one component from another component. The embodiments described and illustrated herein also include complementary embodiments thereof.

In this specification, the singular form also includes the plural form unless specifically stated in the phrase. As used in the specification, "comprise" and/or "comprising" does not exclude the presence or addition of one or more other components.

Hereinafter, the present invention will be described in detail with reference to the drawings. In describing the specific embodiments below, a number of specific contents have been prepared to explain the invention in more detail and to aid understanding. However, readers who have knowledge in this field to the extent that they can understand the present invention can recognize that it can be used without these various specific contents. In some cases, it is mentioned in advance that parts that are commonly known in describing the invention and are not largely related to the invention are not described in order to avoid confusion in describing the invention.

1 is a diagram illustrating an apparatus and method for inspecting a processed product according to an embodiment of the present invention.

Referring to the drawings, the apparatus for inspecting a processed product according to an embodiment includes a 3D image generating unit 100 for a processed product to be inspected (hereinafter simply referred to as “processed product to be inspected”) generating a 3D image of the processed product to be inspected. 1), a reference processed product 3D image generation unit 200 that generates a 3D image of a reference processed product that is a standard processed product to be compared with the processed product to be inspected (hereinafter referred to simply as a “second image generation unit”), A two-dimensional image conversion unit 300 that converts a three-dimensional image of a reference processed product into a two-dimensional image, and a reference laser image extracting unit that extracts a laser image formed on the provisioned processed product or a screen adjacent thereto when the line laser is irradiated on the reference processed product Includes 400.

The first image generating unit 100 generates a 3D image of a processed product to be inspected. For example, the first image generating unit 100 may include at least one of a 3D image generating unit 110 using a camera and/or a 3D image generating unit 120 using a laser.

The 3D image generating unit 110 using a camera captures the processed product to be inspected with the above cameras and generates a 3D image of the processed product to be inspected. The 3D image generation unit 120 using a laser may generate a 3D image of the processed product to be inspected by irradiating a line laser generated by the laser irradiation device onto the surface of the processed product to be inspected and photographing the processed product to be inspected. . In another embodiment, when the line laser is irradiated onto the surface of the object to be inspected, the 3D image generation unit 120 using a laser reflects the image of the laser on the screen disposed adjacent to the object to be inspected by a camera. It is also possible to create a three-dimensional image of the workpiece to be inspected by photographing it. A method of generating a three-dimensional image of a processed product to be inspected from a laser image reflected from the surface of the processed product to be inspected will be described later with reference to FIGS. 4 to 6.

The second image generating unit 200 generates a 3D image of a reference processed product to be compared with an inspection target processed product. In the present invention, a method of generating a three-dimensional image by selecting a good product with the highest processing precision among actual processed products is not used. Instead, in a preferred embodiment of the present invention, the second image generating unit 200 generates 3D image data of the most ideal processed product based on parameters of basic specifications for designing a processed product and parameters of basic specifications of a machining tool for manufacturing the same. Generate. In other words, the'reference processed product' is not a 3D data acquired from an actual processed product, but a virtual processed product generated by computer calculation from the specifications of the processed product and the machining tool.For example, the surface of the processed product (e.g., if the processed product is a gear, the gear teeth It consists of a set of coordinates that make up (齒面)). A detailed configuration of the second image generating unit 200 will be described later with reference to FIGS. 7 and 8.

In an embodiment, the apparatus for inspecting a processed product further includes a first inspection unit that compares the reference processed product and the processed product to be inspected to determine whether the processed product to be inspected is defective. The first inspection unit compares the three-dimensional image of the workpiece to be inspected obtained by the first image generating unit 100 and the three-dimensional image of the reference workpiece generated by the second image generating unit 200 to determine whether the workpiece to be inspected is defective. I can judge.

In an embodiment, the apparatus for inspecting a processed product may acquire and compare two-dimensional images of each of the reference processed product and the processed product to be inspected. To this end, for example, as illustrated in FIG. 1, the 2D image conversion unit 300 may further include a second inspection unit that compares the 2D image and determines whether there is a defect.

The 2D image conversion unit 300 converts a 3D image of a reference processed product into a 2D image. In the illustrated embodiment, a two-dimensional image is converted from a three-dimensional image generated by the first image generating unit 200, but in an alternative embodiment, a two-dimensional image is obtained from a three-dimensional image of a reference processed product obtained in any other way. You can also acquire an image.

On the other hand, the two-dimensional image of the workpiece to be inspected can be obtained by photographing the workpiece to be inspected with a camera, and the second inspection unit includes the two-dimensional image of the workpiece to be inspected and the reference workpiece obtained by the two-dimensional image conversion unit 300. By comparing two-dimensional images, it is possible to determine whether there is a defect. A technology for converting a 3D image into a 2D image will be described later with reference to FIGS. 9 and 10.

In one embodiment, the apparatus for inspecting a processed product may obtain and compare a laser image when a laser is irradiated on the surface of a reference processed product and a laser image when a laser is irradiated on the surface of the processed product to be inspected. As shown in FIG. 1, a third inspection unit for determining whether there is a defect by comparing the reference laser image extraction unit 400 and the laser image may be further included.

The reference laser image extraction unit 400 generates a laser image formed on the Gajun processed product or a screen adjacent thereto when the line laser is irradiated on the reference processed product. For example, the reference laser image extraction unit 400 may extract a reference laser image from a 3D image of the reference processed product generated by the first image generation unit 200.

In one embodiment, the reference laser image extraction unit 400 irradiates a line laser on the surface of the reference processed product and calculates a laser image appearing on the surface of the reference processed product when the surface is photographed with a camera. Since the reference processed product is a virtual processed product that does not exist, the reference laser image is also a virtual laser image. That is, assuming that the laser is irradiated to the reference processed product while the distance of the reference processed product, the laser irradiation device, and the camera are set to predetermined values, the reference laser image is calculated by mathematically calculating the image of the laser shown on the surface of the reference processed product. Can be calculated. A method of calculating the reference laser image displayed on the surface of the workpiece to be inspected will be described later with reference to FIGS. 11 and 12.

The laser image of the workpiece to be inspected can be obtained by actually irradiating the laser to the workpiece to be inspected and photographing the laser line shown on the surface of the workpiece with a camera. At this time, the distance relationship between the object to be inspected, the laser irradiation device, and the camera is determined by the reference laser image extraction unit 400, respectively, of the distances of the reference processed product, the laser irradiation device, and the camera assumed to calculate the reference laser image. Set the same as the value of. The third inspection unit may determine whether or not the inspection object is defective by comparing the reference laser image obtained as above with the laser image displayed on the surface of the object to be inspected.

In an alternative embodiment, the reference laser image extraction unit 400 may irradiate a line laser onto the surface of the reference processed product and calculate a virtual laser image reflected from the surface and projected onto the screen as the reference laser image. Assuming that the laser is irradiated to the reference processed product with the distance relationship between the reference processed product, laser irradiation device, camera, and screen set to predetermined values, the image of the laser reflected from the surface of the reference processed product and reflected on the screen is mathematically calculated. Thus, a reference laser image can be calculated.

At this time, the laser image of the workpiece to be inspected can be obtained by actually irradiating the laser to the workpiece to be inspected and photographing a laser line reflected from the surface of the workpiece and projected onto the screen with a camera. At this time, the distance relationship between the object to be inspected, the laser irradiation device, the camera, and the screen is the reference processed product, the laser irradiation device, the camera, and the screen assumed to calculate the reference laser image by the reference laser image extraction unit 400. It is set equal to each distance relationship. The third inspection unit may determine whether or not the object to be inspected is defective by comparing the reference laser images respectively acquired as above.

The method of determining whether the object to be inspected is defective by using the laser image reflected from the surface of the object to be inspected and displayed on the screen is particularly useful depending on the surface of the object to be inspected or the lighting environment during the operation of the inspection. Can be. For example, in the case of a processed product with extremely low surface roughness or immediately after manufacturing the processed product, it is difficult to use the existing method of inspecting processed products by laser irradiation because the laser line does not appear well on the surface of the processed product even if laser is irradiated on the surface of the processed product. there is a problem. However, if the laser image reflected from the surface of the processed product and formed on the screen as in the present invention is used, the surface of the processed product can be accurately measured even when the surface of the processed product is smooth, so that the inspection of the processed product by laser irradiation can be performed. A method of calculating a reference laser image reflected from the surface of the workpiece to be inspected and applied to the screen will be described later with reference to FIGS. 13 and 14.

Meanwhile, in an embodiment of the present invention, the apparatus for inspecting a processed product may be performed simultaneously or sequentially by combining at least two or more of a three-dimensional image comparison, a two-dimensional image comparison, and/or a laser image comparison. have. For example, the reference laser image extraction unit 400 simultaneously or sequentially while performing an operation of comparing the 3D image of the reference processed product generated by the 3D image generation unit 100 and 200 with the 3D image of the processed product to be inspected. The operation of comparing the laser image of the reference processed product extracted from and the laser image of the laser irradiated on the processed product to be inspected may be performed.

In addition, for example, when the reference laser image extraction unit 400 irradiates the reference processed product with a line laser, a virtual first reference laser image that will be formed on the surface of the reference processed product and a virtual second reference laser image that will be formed on a screen adjacent to the reference processed product After extracting all the laser images formed on the surface of the processed product to be inspected and the screen adjacent to the processed product to be inspected, the virtual first and second reference laser images are compared with each of the corresponding laser images simultaneously or sequentially. You can also check it.

2 is a diagram illustrating an exemplary configuration of an apparatus for inspecting a workpiece according to an embodiment. In the apparatus for inspecting the processed product of FIG. 2, a 3D image generating unit 110 using a camera generates a 3D image of the processed article to be inspected, and the second image generating unit 200 generates an image of the reference processed article and compares it with each other. It may be a device configuration of an inspection device that determines whether the processed product is defective.

In the illustrated embodiment, the workpiece inspection apparatus includes a computing device 10, a camera 21, a camera support 25, a driving unit 30, a workpiece support 35, and a display 40. The processed product support 35 is a member that supports the processed product G to be inspected. The processed product support 35 may be installed on a driving unit 30 composed of a driving motor and an encoder. The driving motor of the driving unit 30 rotates the support 35, and the encoder can accurately measure the amount of rotation of the support 35.

The camera 21 photographs an inspection target processed product G placed on the support 35. The camera 21 is installed on the camera support 25 and can move in the vertical direction. The distance between the camera support 25 and the processed product support 35 is preset to a predetermined distance. While the camera 21 is fixed, the workpiece G can be photographed while rotating the workpiece G to be inspected, and the photographed image is transmitted to the computing device 10. The computing device 10 includes a first image generating unit 100, and the first image generating unit 100 is a three-dimensional image of the processed product based on the image of the processed product G photographed by the camera 21 Create

The computing device 10 may include a first inspection unit that compares a 3D image of a reference processed product previously stored in the device with a 3D image of the processed product to be inspected and determines whether the processed product to be inspected is defective. In addition, a comparison image of two images may be displayed to an operator through the display 40, and the operator may directly compare the two images to determine whether or not the object to be inspected is defective.

A method of generating a three-dimensional image of the object to be inspected G by rotating the object to be inspected G while rotating the camera 21 may use one of various algorithms known in the art. For example, in an embodiment, a "Structure From Motion" (SFM) method of estimating a 3D structure by integrating images taken from multiple angles may be used. However, unlike the general SFM method, in the present invention, a plurality of images are photographed while rotating the workpiece G to be inspected while the camera 21 is fixed without moving, and the location information of the characteristic points (characteristic points) in the photographed image It can be extracted to create a three-dimensional structure of the processed product.

The computing device 10 may further include a 2D image conversion unit 300 and a second inspection unit that compares a 2D image of the reference processed product and the processed product to be inspected to determine whether there is a defect. The 2D image conversion unit 300 converts a 3D image of a reference processed product into a 2D image. The two-dimensional image of the object to be inspected may be directly acquired from an image taken of the object to be inspected (G) with the camera 21, for example.

3 shows an exemplary arrangement of a workpiece inspection apparatus according to an alternative embodiment. Compared with the processed product inspection device of FIG. 2, the processed product inspection apparatus of FIG. 3 generates a three-dimensional image of the processed product to be inspected by the 3D image generating unit 120 using a laser and/or the processed product to be inspected ( It may further include a function of photographing a laser shown on the surface or screen of G) and determining whether the processed product is defective by comparing the photographed laser image and a reference laser image.

To this end, the machined product inspection apparatus of FIG. 3 further includes a second camera 22, a laser irradiation apparatus 50, and a screen 60 in addition to the components of the machined product inspection apparatus of FIG. 2. Although not shown in the drawing, as in FIG. 2, a computing device 10 and a display 40 are provided.

The first camera 21 is arranged to photograph the workpiece G to be inspected placed on the workpiece support 35, and the second camera 22 is arranged to photograph the image of the laser applied to the screen 60. The laser irradiation device 50 may irradiate a line laser toward the workpiece G to be inspected. The screen 60 is disposed to be spaced apart from the workpiece support 35 by a predetermined distance. In the drawings, the screen 60 is shown to be disposed on the upper portion of the workpiece support 35, but this is exemplary, and may be disposed on one or more sides of the workpiece support 35, for example. In addition, two or more screens 60 may be provided. For example, some or all of the reflected images of the laser reflected from the processed product G at various angles by being disposed on one side and the upper surface of the processed product support 35 It can be arranged so that it can be projected. When the laser irradiation device 50 irradiates a laser onto the surface of the processed product G, the first camera 21 may photograph the surface of the processed product G to obtain a laser image. In addition, alternatively, the laser irradiation device 50 irradiates a laser on the surface of the processed product G, and the second camera 22 photographs an image of the laser reflected from the surface of the processed product G and reflected on the screen 60 To obtain a laser image. The laser image thus obtained by the first camera 21 or the second camera 22 is transmitted to the computing device 10.

The computing device 10 includes a 3D image generating unit 120 using a laser. The 3D image generating unit 120 may generate a 3D image of the processed product G from the laser image of the surface of the processed product G acquired by the first camera 21. A method of obtaining three-dimensional shape information of an object by irradiating a laser onto an object is disclosed, for example, in Korean Laid-Open Publication No. 2011-0010300 ("Method of obtaining three-dimensional shape information of a panel"), and the present invention is also known as such. Using the method, it is possible to create a three-dimensional image of the workpiece G to be inspected.

In the present invention, the 3D image generating unit 120 using a laser irradiates a line laser onto the surface of the processed product G to be inspected, and displays the image of the laser reflected from the surface of the processed product and reflected on the screen 60 with the second camera 22 ) To create a 3D image of the workpiece to be inspected. 4 to 6 illustrate an exemplary method of generating a three-dimensional image of an object to be inspected by photographing a laser image appearing on the screen 60 as described above.

Fig. 4 schematically shows the arrangement relationship between the inspection target processed product G, the laser irradiation device 50, the second camera 22, and the screen 60. The laser irradiation device 50 is arranged to irradiate the laser at an angle to the surface of the processed product G to be inspected, and the screen 60 is installed so that all or an egg part of the laser reflected from the surface of the processed product is projected onto the screen 60. Is placed. The second camera 22 is arranged to capture an image of a laser projected on the screen 60. At this time, the distance relationship between the workpiece G to be inspected, the laser irradiation device 50, the second camera 22, and the screen 60 is set in advance and is stored in the computing device 10, for example.

5 is a flow chart illustrating an exemplary method of generating a three-dimensional image of a workpiece G to be inspected using a laser. Referring to the drawing, in step S110, camera coordinates (O _C ), laser coordinates (O _L ), and screen coordinates (O _S ) are set. Since the distance relationship between the inspection object G, the laser irradiation device 50, the second camera 22, and the screen 60 is known, one reference coordinate system is set, and the camera coordinates ( O _C ), laser coordinates (O _L ), and screen coordinates (O _S ) can each be set to the origin coordinates.

Thereafter, in step S120, the laser irradiation device 50 irradiates the line laser L1 onto the workpiece G to be inspected. As shown in Fig. 5, when the workpiece G to be inspected is a gear, for example, when the laser L1 is irradiated on the surface (tooth surface) of the workpiece to be inspected at an angle, the laser is reflected from the surface and the reflected laser (L3) Is projected on the screen 60. The image of this laser L3 projected on the screen 60 is photographed with the second camera 22 to measure the line of the laser L3 (step S130), and the laser L1 from the measured laser L3 image The coordinates of the gear surface reflecting the are calculated (step S140). In this regard, Fig. 6 shows an exemplary method of calculating the coordinates by measuring the shape of the gear surface.

Referring to Fig. 6, when the laser irradiation device 50 irradiates the line laser L1 on the surface of the processed product G at an angle, the line laser L1 has a certain width (thickness). As shown, one end of the laser has a first angle of incidence (α) and is irradiated to the first surface (P11) of the gear, and the other end has a second angle of incidence (β) and is irradiated to the second surface (P21) of the gear. An image of the laser L2 appears in the area between the two points P11 and P21. The laser reflected from the gear surface is projected onto the screen 60 as a line of the laser L3. At this time, the laser of the first surface P11 is reflected at the same reflection angle as the first incident angle α, and the laser at the second surface P21 is reflected at the same reflection angle as the second incident angle β. It is projected on (P12) and the second surface (P22).

When the laser (L3) of the screen (60) is photographed with the second camera (22), the position of the laser (L3) in the screen coordinate (O _S ) can be calculated as a coordinate, and the laser irradiation device 50 and the screen 60 Since the distance and coordinate information of) are already known, the 3D coordinate of the line laser L2 shown on the gear surface can be calculated, and this 3D coordinate becomes the coordinate of the gear surface. In this way, the coordinates of the gear surface can be calculated from the image of the laser L3 projected on the screen 60, and if the above steps are repeated while scanning the line laser L1 over the entire surface of the gear, the three-dimensional surface of the entire gear The coordinate group can be calculated (step S150).

Now, a method of generating a 3D image of the reference processed product by the second image generating unit 200 will be described with reference to FIGS. 7 and 8. In the illustrated embodiment, it is assumed that the reference processed product is a gear.

Fig. 7 is a flow chart of an exemplary method of generating a three-dimensional image of a reference workpiece, and Fig. 8 shows the machining tool surface viewed from the fixed coordinate system Cc and the gear coordinate system Cg of the machining tool.

Referring to FIG. 7, in step S210, basic specifications of a processed product and basic specifications of a machining tool are input. For example, when the processed product is a gear, the general basic specifications of the gear are, for example, parameters such as profile type, pressure angle, twist angle, number of teeth, module, addendum, dedendum, dislocation coefficient, tooth correction method and tooth correction amount. It may include. In general, gears are machined using a cutting tool, and when specifying such a cutting tool for gear processing, the basic specifications of the tool are, for example, tooth type, pressure angle, twist angle, number of teeth, module, addendum, dedendum, tooth thickness, fillet at tooth tip. It may include parameters such as radius and tooth root semi-topping pressure angle.

In addition, when the machining method of the cutting tool is specified, the motion relationship between the tool and the gear is defined during gear machining. For example, such a motion relationship may include parameters such as geometric positional relationship (distance between shafts, shaft angle) and geometrical motion relationship (rotation speed ratio between rotational shafts, feed direction and speed, etc.), for example, between the tool rotational axis and the gear rotational axis. have.

)로 이루어진 벡터(

)로 표현될 수 있고 따라서 절삭공구 치면은 이 벡터가 가리키는 점(Q)의 집합(

)으로 나타낼 수 있다. Thereafter, based on the information input in step S210, a surface (tooth surface) formula of the machining tool is defined based on the fixed coordinate system Oc of the machining tool (step S220). For example, as shown in Fig. 8, the cutting tool tooth surface formula has two independent parameters (

) Of vectors (

) And thus the cutting tool tooth surface is the set of points (Q) pointed to by this vector (

) Can be represented.

Next, in steps S230 and S240, a motion relationship equation between the cutting tool and the gear is defined (S230), and the tooth surface equation of the machining tool is converted into a tooth surface equation based on the gear coordinate system Cg (S240).

)에 변환행렬을 곱하여 기어 고정 좌표계 기준의 공구의 치면 수식(

)으로 변환한다. In one embodiment, a conversion matrix ( M gc ) representing the relative position and relative motion relationship between the cutting tool and the gear is generated, and as shown in Equation 1 below, the tooth surface formula of the tool based on the cutting tool fixed coordinate system (

) Multiplied by the transformation matrix and the tooth surface formula (

).

--- 수학식1

--- Equation 1

)은 절삭공구 치면을 나타내는 2개의 독립매개변수(

)와 상대운동관계를 나타내는 1개의 독립매개변수(

)가 합쳐져 총 3개의 독립매개변수(

)로 표현된다. If you type in Equation 1, the formula (

) Are two independent parameters representing the cutting tool tooth surface (

) And 1 independent parameter (

) Is added to the total of 3 independent parameters (

).

Next, in step S250, the meshing equation is defined as the boundary condition of the gear tooth surface, and a three-dimensional tooth surface coordinate group of the gear surface satisfying the same is calculated (S260).

)의 법선벡터와 상대속도 벡터를 각각 수식으로 표현하고 그 둘을 내적하여 물림방정식을 정의할 수 있다. In step (S250), the meshing equation is defined as an equation that the surface of the gear should not enter the cutting tool when the cutting tool and the gear mesh with each other.For example, as shown in Equation 2 below, cutting based on the fixed gear coordinate system Tool tooth surface (

The normal vector and the relative velocity vector of) can be expressed as equations, and the interpolation equation can be defined by dot product of the two.

--- 수학식2

--- Equation 2

)은 3개의 독립매개변수(

)로 표현되어 있으므로 표면(surface)이 아닌 부피(volume)를 나타낸다. 물림방정식은 3개의 독립매개변수(

)로 표현되는 조건식이다. 따라서 아래 수학식3으로 나타낸 것처럼, 수학식1과 수학식2(물림방정식)에 의해 3개의 매개변수(

) 중 1개는 종속매개변수로 바뀌게 되고 2개의 독립매개변수(

)가 절삭공구 치면을 나타내는 수식이 되고, 이 수식이 결국 가공된 기어의 3차원 표면을 나타내는 기어 치면 좌표군(

)이 된다. Cutting tool tooth surface based on the fixed gear coordinate system (

) Is the three independent parameters (

), so it represents the volume, not the surface. The bite equation consists of three independent parameters (

It is a conditional expression expressed as ). Therefore, as shown in Equation 3 below, the three parameters (

), one of the parameters is changed to the dependent parameter and two independent parameters (

) Becomes the formula representing the cutting tool tooth surface, and this formula eventually represents the three-dimensional surface of the machined gear.

).

--- 수학식3

--- Equation 3

As described above, in the present invention, since the 3D image data of the processed product is generated based on the parameter of the basic specification for designing the processed product and the parameter of the basic specification of the machining tool for manufacturing the same, a good product is selected from the actual processed product, and the reference processed product is scanned. Compared to the conventional method of generating the data, it is possible to obtain more precise and ideal reference workpiece data.

Now, a technology for converting a 3D image to a 2D image will be described with reference to FIGS. 9 and 10. The operation of converting a 3D image to a 2D image may be performed, for example, by the 2D image conversion unit 300 of FIG. 1.

9 is a diagram schematically showing the relationship between a virtual reference processed product (VG) and the first camera 21, and FIG. 10 is a flowchart of an exemplary method for converting a 3D image of a reference processed product into a 2D image.

In FIG. 9, it is assumed that the first camera 21 photographs the reference processed product VG at a predetermined distance. At this time, the reference processed product (VG) is not a real object, but it is assumed that it is placed on the processed product support (35), and this processed product (VG) is photographed by the first camera (21) disposed at a predetermined distance from the support (35). Is assumed to be. In this case, the coordinate system OM is a reference coordinate system, and may be, for example, a world coordinate system or an arbitrary coordinate system such as a gear coordinate system described in FIGS. 6 to 8. The coordinate system O _C is the camera coordinate system.

)일 수 있다. Referring to FIG. 10, in step S310, a three-dimensional tooth surface of a gear is defined in a reference coordinate system O _M. That is, it defines a set of three-dimensional coordinates of the gear viewed from the reference coordinate system (O _M ). For example, when the reference coordinate system is the gear coordinate system described in Figs. 6 to 8, the gear tooth surface coordinate group shown in Equation 3 of the three-dimensional coordinates of the gear (

) Can be.

After that, the camera coordinates Oc are set in step S320, and the camera parameters K, R, and T are calculated in step S330. That is, camera parameters are calculated according to how far the camera coordinate (OC) is from and rotated from the reference coordinate system (O _M ).

In this case, K is an internal variable of the camera, and has different values for each camera, such as a camera lens or an image sensor array, and may be expressed as a matrix as in Equation 4 below.

--- 수학식4

--- Equation 4

In Equation 4 above, each variable is shown in Table 1 below.

ingredient designation Explanation u ₀ , v ₀ Principal point Camera center α, β Focal Length Camera focal length (in pixel) γ Skew Parameter Degree of distortion of the image sensor (manufacturing process)

Among the camera parameters, "R" and "T" are external variables of the camera, where R represents the degree of rotation of the camera based on the reference coordinate system (O _M ), and T represents the parallel movement distance between the reference coordinate system (O _M ) and the camera coordinate. It is expressed as a matrix.

After that, in step S340, the three-dimensional tooth surface coordinates are converted into two-dimensional image coordinates viewed from the first camera 21 by using the camera parameters. In one embodiment, as shown in Equation 5 below,

Find the coordinates of a two-dimensional image.

--- 수학식5

--- Equation 5

In Equation 5 above, "X" is the coordinate of the gear surface viewed from the reference coordinate system (OM), "x" is the coordinate of the gear surface viewed from the first camera 21, and [R|T] is an external variable of the camera. Is the determinant of

After converting the 3D image of the reference processed product VG into the coordinates of the 2D image viewed from the first camera 21 as above, step S350 of applying a camera distortion parameter may be additionally performed as necessary. In general, the camera may distort the image as it moves toward the periphery of the lens, and if such distortion exists, the operation of correcting the distortion may be performed in step S350.

Now, a method of calculating the reference laser image displayed on the surface of the workpiece to be inspected will be described with reference to FIGS. 11 and 12. The operation of calculating the reference laser image may be performed, for example, in the reference laser image extraction unit 400 of FIG. 1.

11 is a diagram schematically showing the relationship between the virtual reference processed product (VG), the first camera 21, and the laser irradiation device 50, and FIG. 12 is a reference laser in a three-dimensional image of a reference processed product according to an embodiment. It is a flow chart of how to extract an image.

In FIG. 11, it is assumed that the laser irradiation device 50 irradiates a line laser on the surface of the virtual reference processed product VG, and at this time, the first camera 21 photographs a laser image displayed on the surface of the reference processed product. The reference processed product (VG) is not a real object, but assuming that it is placed on the processed product support 35, the distance relationship between the processed product support 35, the first camera 21, and the laser irradiation device 50 is a preset value. It is known as, and calculates a laser image of the surface of the processed product assuming that the laser irradiation device 50 irradiates a line laser toward the surface of the reference processed product (VG) and the first camera 21 photographs the surface of the processed product. will be. At this time, the coordinate system (O _M ) is a reference coordinate system, for example, a world coordinate system or an arbitrary coordinate system such as the gear coordinate system described in FIGS. 6 to 8, and the coordinate system (O _C ) is a camera coordinate system, and the coordinate system (O _L ) is a laser irradiation device. Is the coordinate system of

)일 수 있다. Referring to FIG. 12, in step S410, the three-dimensional tooth surface of the gear is defined in the reference coordinate system O _M. That is, it defines a set of three-dimensional coordinates of the gear viewed from the reference coordinate system (O _M ). For example, when the reference coordinate system is the gear coordinate system described in Figs. 6 to 8, the gear tooth surface coordinate group shown in Equation 3 of the three-dimensional coordinates of the gear (

) Can be.

Thereafter, the camera coordinate (Oc) and the laser coordinate (OL) are set in step S420, and in step S430, the laser irradiation device 50 irradiates the laser at a predetermined angle on the surface of the reference processed product VG, and When the first camera 21 captures a laser image formed on the surface, a laser image is calculated. Since the distance relationship between the workpiece support 35 and the laser irradiation device 50 is already known, the laser irradiated at a predetermined angle by the laser irradiation device 50 can be calculated at which position on the surface of the reference workpiece VG.

After that, the camera parameters (K, R, T) are calculated in step S440. The camera parameter has the same meaning as the camera parameter described with reference to step S330 of FIG. 10 and may be calculated in the same or similar manner as that described with reference to FIG. 10, so a description thereof will be omitted.

Next, in step S450, the laser image of the camera coordinate system is calculated using the camera parameters. That is, the laser image formed on the surface of the reference processed product VG is converted into an image viewed from the viewpoint of the first camera 21. This step may be transformed using a coordinate transformation matrix based on the camera parameters R and T similarly to that described with reference to step S340 of FIG. 10. Thereafter, although not shown in the drawing, a step of applying a camera distortion parameter may be further added, if necessary, similar to step S350 of FIG. 10, for example.

Now, a method of calculating a reference laser image reflected from the surface of the workpiece to be inspected and formed on the screen will be described later with reference to FIGS. 13 and 14. This method may be executed, for example, in the reference laser image extraction unit 400 of FIG. 1.

13 is a diagram schematically showing the relationship between the virtual reference processed product (VG) and the second camera 22, the laser irradiation device 50, and the screen 60, and FIG. 14 is a reference in the three-dimensional image of the reference processed product. It is a flow diagram describing an exemplary method for extracting a laser image.

In FIG. 13, the laser irradiation device 50 irradiates a line laser on the surface of the virtual reference processed product VG, and at this time, the second camera 22 displays the laser image reflected from the reference processed product surface and projected onto the screen 60. Suppose you are shooting. The reference processed product (VG) is not a real object, but it is assumed that it is placed on the processed product support (35), and the distance between the processed product support (35), the second camera (22), the laser irradiation device (50), and the screen (60) The relationship is known as a preset value, and a virtual laser image to be formed on the screen 60 by irradiating a line laser (L1) from the laser irradiation device 50 toward the surface of the reference processed product (VG) and reflecting off the surface of the processed product. The laser image L3 is calculated assuming that the second camera 22 photographs (L3). At this time, the coordinate system (O _M ) is a reference coordinate system, for example, a world coordinate system or an arbitrary coordinate system such as the gear coordinate system described in FIGS. 6 to 8, and the coordinate system (O _C ) is a camera coordinate system, and the coordinate system (O _L ) is a laser irradiation device. The coordinate system of, O _S is the screen coordinate system.

)일 수 있다. Referring to FIG. 14, in step S510, a three-dimensional tooth surface of a gear is defined in a reference coordinate system O _M. That is, it defines a set of three-dimensional coordinates of the gear viewed from the reference coordinate system (O _M ). For example, when the reference coordinate system is the gear coordinate system described in Figs. 6 to 8, the gear tooth surface coordinate group shown in Equation 3 of the three-dimensional coordinates of the gear (

) Can be.

After that, in step (S520), camera coordinates (O _C ), laser coordinates (O _L ), and screen coordinates (O _S ) are set, and in step (S530), the laser (L1) is irradiated to the reference workpiece (VG). At this time, the incident angle and the reflection angle of the laser reflected from the reference processed product surface are calculated, and in step S540, the coordinates of the virtual laser image L3 reflected from the reference processed product surface and formed on the screen surface are calculated.

Since the distance relationship between the workpiece support 35, the second camera 22, the laser irradiation device 50, and the screen 60 is already known, the laser irradiation device 50 is placed on the surface of the reference processed product VG. The laser image when the second camera 22 captures a laser image reflected from the surface of the processed product and reflected on the screen 60 by irradiating the laser at an angle can be calculated.

After that, the camera parameters K, R, and T are calculated in step S540, and the laser image of the camera coordinate system is calculated using the camera parameters in step S50. This step (S540, S550) can be performed in a similar manner to the steps (S440, S450) of FIG. 12, respectively, so a description thereof will be omitted. Also, similar to step S350 of FIG. 10, a step of applying a camera distortion parameter may be further added as needed.

Fig. 15 is a block diagram showing an exemplary system configuration for implementing a method for inspecting a workpiece according to an embodiment.

Referring to FIG. 15, the apparatus 10 for inspecting a workpiece performing a method for inspecting a workpiece according to an embodiment is capable of executing the steps of the flowchart shown in FIGS. 5, 7, 10, 12, and/or 14. It may be any computing device and may include a processor 11, a memory 12, and a storage device 13 as shown.

The storage device 13 is a storage medium capable of semi-permanently storing data, such as a hard disk drive or a flash memory, and includes an algorithm for performing the flowcharts of Figs. 5, 7, 10, 12, and/or 14. can do. For example, the storage device 13 can be executed by the first image generating unit 100 and can be executed by the algorithm 150 for generating a three-dimensional image of the workpiece to be inspected, and the second image generating unit 200 Algorithm 250 for generating a three-dimensional image of, the two-dimensional image conversion unit 300, an algorithm for converting a three-dimensional image of a reference processed product into a two-dimensional image 350, a reference laser image extraction unit 400 Algorithm 450 for extracting and converting a laser line formed on the surface or screen of a processed product into a two-dimensional image, and a comparison and inspection algorithm 500 that compares a reference processed product with a processed product to be inspected and determines whether there is a defect, etc. At least one of the software can be stored.

These various programs or algorithms may be stored in the storage device 13 and then loaded into the memory 12 under the control of the processor 110 and executed. Alternatively, some programs or algorithms may exist in an external device or server that exists separately from the system 10, and when the system 10 requests data or variables from the corresponding external device or server, the external device or server After executing a program or algorithm, the resulting data may be transmitted to the system 10.

As described above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited to the above embodiments. Those of ordinary skill in the art to which the present invention pertains will understand that various modifications and variations are possible from the above description. Therefore, the scope of the present invention is limited to the described embodiments and should not be defined, but should be defined by the claims to be described later as well as equivalents to the claims.

10: computing device 21, 22: camera
25: camera support 30: driving unit
35: workpiece support 40: display
50: laser irradiation device 60: screen
100: 3D image generation unit of the processed product to be inspected
200: reference processed product 3D image generation unit
300: 2D image conversion unit
400: reference laser image extraction unit

Claims (15)

As a processed product inspection method that compares the processed product to be inspected with the standard processed product to determine whether the processed product to be inspected is defective,
Generating a three-dimensional image of a virtual reference processed product based on a basic specification parameter of the processed product, a basic specification parameter of a machining tool for processing the processed product, and a motion relationship between the machining tool and the processed product;
Generating a three-dimensional image of the workpiece to be inspected using a camera or a line laser; And
And a first inspection step of comparing the 3D image of the reference processed product with the 3D image of the processed product to be inspected to determine whether the processed product to be inspected is defective. The method of claim 1, wherein generating a three-dimensional image of the reference processed product comprises:
Defining a surface formula of the machining tool based on a fixed coordinate system of the machining tool;
Defining a motion relationship equation between the workpiece and the machining tool; And
And converting the surface formula of the machining tool into a surface formula based on the work piece coordinate system. The method of claim 2, wherein generating a three-dimensional image of the processed product to be inspected comprises:
Irradiating the line laser to the workpiece to be inspected;
Measuring a laser image reflected from the surface of the workpiece to be inspected and formed on the screen; And
And calculating the coordinates of the surface of the processed article reflecting the laser from the measured laser image. The method of claim 1,
Calculating a first virtual laser image of the surface of the reference processed product when irradiating the line laser to the reference processed product;
Irradiating a line laser on the workpiece to be inspected to take a second laser image of the surface of the workpiece to be inspected; And
And a second inspection step of comparing the first laser image and the second laser image to determine whether or not the object to be inspected is defective. The method of claim 4, wherein calculating the first laser image comprises:
Calculating coordinates of the first laser image on the surface of the reference processed product when the laser is irradiated on the reference processed product;
Calculating camera parameters of a camera for photographing a processed product to be inspected; And
And converting the coordinates of the first laser image into coordinates based on the camera coordinate system based on the camera parameter. The method of claim 1,
Calculating a virtual first laser image reflected from the surface of the reference processed product and formed on the screen when the laser is irradiated on the reference processed product;
Irradiating a line laser on the workpiece to be inspected to take a second laser image of the surface of the workpiece to be inspected; And
And a second inspection step of comparing the first laser image and the second laser image to determine whether or not the object to be inspected is defective. The method of claim 6, wherein calculating the first laser image comprises:
Calculating an incident angle and a reflection angle of the laser reflected from the surface of the reference processed product when irradiating the laser to the reference processed product;
Calculating coordinates of the first laser image reflected from the surface of the reference processed product and formed on the screen surface;
Calculating camera parameters of a camera that will take a first laser image of the screen; And
And converting the coordinates of the first laser image into coordinates based on the camera coordinate system based on the camera parameter. As a processed product inspection device that compares the processed product to be inspected with the standard processed product to determine whether the processed product to be inspected is defective,
A support 35 for supporting the processed product to be inspected;
A drive motor 30 for rotating the support;
A first camera 21 spaced apart from the support for photographing a processed product to be inspected;
An inspection target processed product image generation unit 100 for generating a three-dimensional image of the inspection target processed product photographed by the first camera; And
Including; a first inspection unit for determining whether or not defective by comparing the three-dimensional image of the workpiece to be inspected with a three-dimensional image of a virtual reference workpiece; and
The 3D image of the reference processed product is generated based on a basic specification parameter of the processed product, a basic specification parameter of a machining tool for processing the processed product, and a motion relationship between the machining tool and the processed product. The method of claim 8,
Further comprising a reference processed product image generation unit 200 for generating a three-dimensional image of the reference processed product, the reference processed product image generation unit,
Defining a surface equation of the machining tool based on a fixed coordinate system of the machining tool based on the basic specification parameter of the workpiece and the basic specification parameter of the machining tool;
Defining a motion relationship equation between the workpiece and the machining tool; And
Converting the surface formula of the machining tool into a surface formula based on the work piece coordinate system to generate a three-dimensional image of the reference work piece. The method of claim 9,
A laser irradiation device 50 for irradiating a line laser toward the workpiece to be inspected installed on the support;
A screen 60 disposed to be spaced apart from the support by a predetermined distance; And
And a second camera (22) which is irradiated by the laser irradiation device and reflected on the surface of the workpiece to be inspected to photograph a laser image of the laser attached to the screen. The method of claim 10,
The inspection target processed product image generation unit 100 generates a 3D image of the inspection target processed product based on the laser image photographed by the second camera. The method of claim 10,
A laser image extraction unit for calculating a first virtual laser image of the surface of the reference processed product when the laser irradiated by the laser irradiation device is irradiated onto the reference processed product; And
When the laser irradiation device irradiates a laser on the workpiece to be inspected, the second laser image on the surface of the workpiece to be inspected photographed by the first camera is compared with the first laser image calculated by the laser image extraction unit to determine whether there is a defect. Processed product inspection apparatus further comprising a; second inspection unit to. The method of claim 12, wherein the laser image extraction unit,
Calculating coordinates of the virtual first laser image on the surface of the reference processed product when the laser is irradiated on the reference processed product;
Calculating a camera parameter of the first camera; And
Converting the coordinates of the first laser image into coordinates based on a camera coordinate system based on the camera parameter to calculate the first laser image. The method of claim 10,
When the laser irradiation device irradiates a laser to a reference processed product, a laser image extracting unit for calculating a virtual first laser image reflected from the surface of the reference processed product and formed on the screen; And
When the laser irradiation device irradiates the laser to the object to be inspected, the second laser image on the surface of the object to be inspected, photographed by the first camera, is compared with the first laser image calculated by the laser image extraction unit to determine whether there is a defect. Processed product inspection apparatus further comprising a; second inspection unit to. The method of claim 14, wherein the laser image extraction unit,
Calculating the incident angle and reflection angle of the laser irradiated and reflected on the surface of the reference processed product when the laser irradiation device irradiates the laser onto the reference processed product;
Calculating camera parameters of the second camera; And
Converting the coordinates of the first laser image into coordinates based on a camera coordinate system based on the camera parameter to calculate the first laser image.

Images