KR101803473B1 - Apparatus and method for inspecting parts using line scanning - Google Patents

Abstract

The present invention relates to a method and an apparatus for checking whether a part is defective by using line scanning, and in this specification, a light emitting diode (LED) for a machined part produced by a computer numerical control (CNC) ) Line scan image and measuring the distance between the inflection points at which the scan line in the LED line scan image is changed, thereby determining whether or not the machining part is defective.

Description

TECHNICAL FIELD [0001] The present invention relates to an apparatus and method for inspecting parts using line scanning,

The present invention relates to a component inspection method and apparatus. More particularly, the present invention relates to a method and apparatus for inspecting whether a component is defective by using line scanning.

Numerical control (NC) is a method of automatically controlling the machine through numerical information composed of numerical values and signs. Specifically, a command tape is formed by punching information on the shape and processing conditions of the workpiece, and a servo is controlled by generating a pulse based on the command tape. In addition, computer numerical control (CNC) is sometimes used in combination with NC, and it controls the machine mechanism by using a dedicated computer such as a microcontroller.

On the other hand, a lathe is a machine tool that rotates a material to be cut and carries out cutting or digging with a fixed cutting tool (cutting tool), and the CNC lathe is a CNC-controlled lathe. Products that have been processed by these CNC lathe processes must undergo a process of screening for defective products and an inspection process is required. Since CNC lathe works are produced by continuously machining several hundred parts, it is sometimes difficult to inspect all the machined parts. In addition, when inspecting machined parts at regular intervals, if a continuous defective part finds the shipment late, it often happens that many products need to be reproduced again. As a result, the process of selecting a defective product results in a delay in the operation speed and adversely affects the production of parts. Therefore, it is necessary to develop a measurement method that is cheaper and simpler in function than the conventional inspection system, which requires high labor costs due to unnecessary labor and time wasted in inspection work.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a method and an apparatus for checking whether a component is defective by using a light emitting diode and an image processing technique.

In order to accomplish the above object, there is provided a method of inspecting parts manufactured by a computer numerical control (CNC) lathe, comprising the steps of: performing a line scan Measuring a distance between at least one inflection point that is a discrepancy point between a plurality of scan lines included in the pattern among the scan patterns included in the line scan image, and calculating a distance between the at least one inflection points And determining whether or not the component is defective as a basis.
In the embodiment, the acquiring of the line scan image may include adjusting at least one of the light amount, the irradiation direction, and the time of the LED according to the type of the component, performing line scan on the component in accordance with the scan pattern And performing noise reduction and monochrome conversion on the image obtained from the line scan.
In an embodiment, measuring the distance between the inflection points may include extracting edges of each of the plurality of scan lines, obtaining a center line of the scan lines from the edges, And calculating an error between the mismatched center-point lines among the mismatched center-point lines.
In the embodiment, the step of determining whether or not the component is defective may determine that the component is defective if the error between the center-point lines exceeds the reference dimension.
In an embodiment, the at least one inflection point is located at a boundary of a portion having a different height according to the structure of the part.
In an embodiment, the scan pattern may be a cross pattern or a lattice pattern.
An apparatus for inspecting parts manufactured by a computer numerical control (CNC) lathe according to various embodiments of the present invention includes an LED inspection unit for irradiating a light emitting diode (LED) An input unit for obtaining a line scan image of a part irradiated with an LED using the scan pattern, and a display unit for displaying a distance between at least one inflection point, which is a mismatch point between the plurality of scan lines included in the pattern, To determine whether the component is defective or not.
In an embodiment, the LED irradiating unit includes an LED light source, a scan pattern including a plurality of lines, and an extension preventing lens for preventing extension of light of the LED light source.
In an embodiment, the scan pattern may be a cross pattern or a lattice pattern.
In an embodiment, the control unit includes an environment variable control unit for controlling the LED light amount, the illumination direction or the time of the LED illuminating unit, and an image processing unit for removing the noise of the line scan image and converting the noise into a monochrome image.

According to various embodiments of the present invention, the height of the CNC machined part can be measured without touching the dimensions of different parts.

In addition, according to various embodiments of the present invention, it is possible to configure a system with a thin line, a sharp edge, and uniform contrast by using a line scan LED in comparison with a line scan using a laser of the same cost.

1 is a view showing a CNC lathe machining part inspection system including a parts inspection apparatus according to an embodiment of the present invention.
2 is a block diagram showing a configuration of a part inspection apparatus according to the present invention.
3 is a view showing a structure of an LED irradiating unit of the component inspecting apparatus of the present invention.
4 is a view for explaining a process of irradiating a processed part with an LED light and acquiring the image in the part inspection apparatus according to an embodiment of the present invention.
5 is a view showing an embodiment of a line scan pattern of the LED irradiating unit of the component inspection apparatus of the present invention.
6 is a view for explaining inflection points in an image obtained by the input unit of the component inspection apparatus of the present invention.
7 is a view for explaining a process of extracting a center point of an LED scan line for accurate dimension measurement in an LED scan line image.
8 is a block diagram showing the structure of the control unit of the parts inspection apparatus of the present invention.
FIG. 9 is a flowchart showing the operation of the parts inspection apparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the following description of the embodiments of the present invention, descriptions of techniques which are well known in the technical field of the present invention and are not directly related to the present invention will be omitted. This is for the sake of clarity of the present invention without omitting the unnecessary explanation.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is provided to fully inform the owner of the scope of the invention.

1 is a view showing a CNC lathe machining part inspection system including a parts inspection apparatus according to an embodiment of the present invention.

1, the CNC lathe machining part inspection system may include a CNC lathe machining part machine 100, a transfer robot arm 200, and a parts inspection apparatus 300.

The CNC lathe machining part machine 100 includes CNC-operated lathe and lathe machined parts. Here, the processing method and type of the parts processed through the lathe are not limited, and the inspection system of the present invention can be applied to all parts machined with a CNC lathe.

The transfer robot arm 200 can transfer the machined part of the CNC lathe machining part machine 100 to the parts inspection apparatus 300. In various embodiments, the transport robotic arm 200 may move the machined part to the camera lens of the part inspection apparatus and move the inspected part back to the machined transport part machine 100 for the CNC lathe. Here, the moving robot arm 200 can move the machining part simultaneously or sequentially. Further, in the present invention, the transfer robot arm 200 does not limit the manner in which the parts are moved, and the transfer robot arm 200 transfers the machined parts to the CNC lathe machining part machine 100 and the parts inspection apparatus 300).

The part inspection apparatus 300 can check whether or not a defective machining part moved from the machining part machine for the CNC lathe by the transfer robot arm 200 is defective. The parts inspection apparatus 300 may include a jig for positioning the machined part to check whether the machined part is defective. The transfer robot arm 200 can accurately mount the machined part on the jig. However, the description of the process of placing the machined part on the jig by the robot arm 200 for transfer is omitted here. The operation of the parts inspection apparatus 300 will be described in more detail with reference to FIGS. 2 to 8. FIG.

2 is a block diagram showing a configuration of a part inspection apparatus according to the present invention.

2, the component inspection apparatus 300 of the present invention may include an input unit 310, an LED irradiation unit 320, a control unit 330, a storage unit 340, and a display unit 350.

When the LED irradiating unit 320 irradiates light to a component to be inspected, the input unit 310 can acquire the light in an image form. In various embodiments, the input 310 may be a camera module. The camera module that can be applied to the input unit 310 may be a two-dimensional camera or a three-dimensional camera, and is not limited to any one type. Also, the input unit 310 can receive information about a component to be inspected through a user input, a bar code input through a camera, and the like. The information on the component to which the input unit 310 is input may include information on the name of the component, the type, the date of production, and the like, and may include component specification information related to the size, shape, or dimensions of the component. The input unit 310 may acquire an image of the component by adjusting parameters of each component of the camera module according to information about the input component.

The LED irradiating unit 320 can irradiate an LED light source to a part to be inspected. The LED illuminating unit 320 may illuminate the LED light to perform line scan, i.e., line scan. The color or type of the LED used by the LED irradiating unit 320 is not limited. The LED irradiating unit 320 can adjust the environmental variable of the LED irradiating unit 320 according to the inspection target part before irradiating the inspection target part with the LED light. Here, the environmental variable controlled by the LED irradiating unit 320 may include at least one of variables related to the LED light quantity, the irradiation direction of the LED light, and the time depending on the type of the component.

The control unit 330 can control the overall operation of the parts inspection apparatus according to the present invention. Specifically, the controller 330 can control the components of the camera module included in the input unit 310, and can control the adjustment of the environmental variables of the LED irradiator 320 according to the component to be inspected. In addition, the controller 330 may perform a preprocess to measure the dimensions of the image obtained by the input unit 310. Specifically, the controller 330 removes the noise of the obtained image and separates the channel and converts the separated image into a monochrome image (gray).

The control unit 330 can measure the dimensions of the corresponding component using the inflection point length measurement method in the image converted into the monochrome image. The inflection point length measurement method will be described later in detail with reference to FIGS. 5 to 7, and will not be described here.

The control unit 330 can determine whether the component is defective through the component-related information stored in the storage unit 340 or input by the input unit 310 and the measured dimensions of the component. The control unit 330 may display the determination result on the display unit 350 or may transmit a stop signal to the CNC lathe machining part machine 100 or the transfer robot arm 200 through a communication unit .

3 is a view showing a structure of an LED irradiating unit of the component inspecting apparatus of the present invention.

3, the component inspection apparatus 300 of the present invention may include an LED irradiation unit 320 that irradiates light to components to be inspected, and the LED irradiation unit 320 includes an LED light source 321, (322), and an extension-preventing lens (323).

각도를 유지하면서 부품에 빛을 조사할 수 있다. The LED light source 321 emits light from the LED to the part to be inspected. In various embodiments, the LED light source 321 may include at least one or more LED elements. In the present invention, the type and size of the LED element that can be used as the LED light source 321 are not limited. The LED light source 321 is arranged in the normal direction of the paper so as not to affect the camera radius of the input unit 310

The light can be irradiated to the part while maintaining the angle.

The line scan pattern 322 is a pattern for performing line scan, and one or more various patterns can be applied to the component inspection apparatus of the present invention. The line scan pattern 322 to be applied is described in detail later in FIGS. 5 to 7 Explain.

When the light is irradiated by the LED irradiating unit 320, the extension preventing lens 323 allows the linear expansion to occur even if it is tilted in one direction. In various embodiments, the widening lens 323 may be a unidirectional anti-linear lens (Bi-telecentric lens, etc.). The extension preventing lens 323 makes it possible to minimize the distortion of the irradiation line.

4 is a view for explaining a process of irradiating a processed part with an LED light and acquiring the image in the part inspection apparatus according to an embodiment of the present invention.

각도로 가공 부품에 광을 조사하도록 입력된 부품 관련 정보에 따라 LED조사부(320)를 제어할 수 있다.According to Fig. 4, the LED irradiating unit 320 can irradiate the LED light toward the workpiece. At this time, the controller 330 controls the LED irradiator 320

It is possible to control the LED irradiating unit 320 according to the information related to the parts inputted so as to irradiate the processed part with light at an angle.

When the processed part is irradiated with the LED light, the input unit 310 can acquire the corresponding image through the camera. The control unit 330 removes the noise of the image input from the input unit 310 and converts the obtained image into a monochrome image by separating the channel. Then, it is possible to judge whether or not the machined part is defective by using the inflection point length measuring method which will be described later.

Hereinafter, a method of measuring the length by extracting an inflection point from the obtained image will be described in detail.

5 is a view showing an embodiment of a line scan pattern of the LED irradiating unit of the component inspection apparatus of the present invention.

Referring to FIG. 5, the line scan pattern used in the present invention may be a cross-shaped line scan LED pattern 510 or a grid-like line scan LED pattern 520.

In the case of the grid-shaped line scan LED pattern 520, a second-order diffraction pattern due to inter-grid interference can occur compared to the cross-shaped line scan LED pattern 510. In addition, linear expansion occurs in the horizontal direction, and the interval between the lattices may gradually become distant. Therefore, it may be more advantageous to use the cross-shaped line scan LED pattern 510, except that the structure of the machined part is complex or there are many portions having different heights.

Although only a cross-shaped line scan LED pattern 510 or a lattice-shaped line scan LED pattern 520 is shown in the present invention as a line scan pattern, various scan patterns that can be used for line scan may be applied to the present invention .

6 is a view for explaining inflection points in an image obtained by the input unit of the component inspection apparatus of the present invention.

According to Fig. 6, when the LED light source is irradiated on the machined part, it can be seen that the LED scan lines are not aligned in a straight line in the portion where the height of the machined part is different. That is, the scan lines of the LED scan lines are bent at the boundaries of the different heights depending on the structure of the processed parts. At this time, the breaking distance can be proportional to the height difference of the structure. In this specification, a point at which the scan line is bent is referred to as an inflection point.

According to the present invention, when the inflection point is extracted from the obtained image after line scan is performed on the processed part, and the distance between the inflection points is measured, the dimensions of the part can be obtained without contact. Therefore, faster and more accurate component inspection can be possible. Hereinafter, a method of measuring the distance between the inflection points by extracting the center points of the scan lines will be described in more detail with reference to FIG.

7 is a view for explaining a process of extracting a center point of an LED scan line for accurate dimension measurement in an LED scan line image.

Referring to FIG. 7, when a line scan LED is partially irradiated on a circular workpiece having a different height, the LED line irradiated on the concave-convex portion of the component is bent due to the irradiation angle and the relative position of the component. In the present invention, the distance between the inflection point and the inflection point is measured to measure the dimension of each part of the part. This makes it possible to measure precise dimensions of the machined parts and to judge whether or not there is a defect. Machined parts may be in the form of untreated metal, which can cause diffuse diffraction and interference, if necessary. In order to minimize such a problem, the component inspection apparatus of the present invention minimizes the thickness of the LED scan line and controls the exposure time in the camera shooting so as to reduce the line thickness while being exposed to the strong light of the center line Investigate. Observing the LED scan lines of the color source images taken and photographed, speckle may occur in the lines themselves, like sparkling sands due to the inherent coherence of monochromatic light. Therefore, in the image preprocessing step, we obtain a gray level image that can measure LED scan lines by using image processing techniques such as morphology and channel separation.

However, as shown in FIG. 7, when the LED scan line is enlarged, the boundary of the edge portion may not be clear or an uneven shape may appear. Therefore, to measure the distance between the inflection points, the center line of the LED scan line is extracted and the distance is measured. If the tolerance is exceeded, it is judged to be defective and the stop signal can be transmitted to the CNC lathe machining part system and the transfer robot ARM.

8 is a block diagram showing the structure of the control unit of the parts inspection apparatus of the present invention.

Referring to FIG. 8, the control unit 330 of the parts inspection apparatus of the present invention can largely include an environment variable control unit 331 and an image processing unit 332.

8, the control unit 330 displays only the environment variable control unit 331 and the image processing unit 332. However, the control unit 330 includes a plurality of modules for performing other functions . Since the control unit 330 controls the overall operation of the parts inspection apparatus according to the present invention as described above, the control unit 330 does not include the environment variable control unit 331 and the image processing unit 332 shown in FIG. 8, Specifies that the control can perform all operations.

The environment variable control unit 331 includes a component control function for controlling various components of the input unit 310 and an environment variable control function for controlling environment variables.

The image processing unit 332 includes an image preprocessing function for reducing noises of the obtained processed part image and separating the channels, and an image processing function for extracting the center point of the LED scan line and informing the dimension information. In various embodiments, the image processing unit 322 compares the measured dimensional information with the reference dimensional information, and if it is normal, performs the dimensional measurement inspection continuously, and if it is defective, transmits the stop signal to the CNC lathe machining part system and the transfer robot ARM As shown in FIG.

FIG. 9 is a flowchart showing the operation of the parts inspection apparatus according to an embodiment of the present invention.

According to FIG. 9, first, the parts inspection apparatus can receive information of the machined part (910). The information of the machined part may be inputted in advance by the user or inputted in advance according to the bar code input through the camera or preset scheduling information. The information on the processed parts to be received may include information on the name of the part, the type, the date of production, and the like, and may include part specification information related to the size, shape, or dimensions of the part.

The part inspection apparatus irradiates the LED light source to a part to be inspected, performs a line scan, and obtains the result in an image form (920). At this time, in order to irradiate the LED light source, the environment variable can be adjusted according to the previously entered information about the parts to be processed. The environmental variable to be adjusted may include at least any one of variables relating to LED light quantity, irradiation direction of LED light, and time depending on the type of the component. In addition, the camera parts can be set according to the previously entered information about the parts to be processed for image acquisition.

In step 930, the part inspection apparatus can extract the inflection point on the acquired image and measure the distance between the inflection points. Specifically, the component inspection apparatus converts the acquired image into a gray level image capable of measuring an LED scan line by using an image processing technique such as a morphology technique and channel separation in a pre-processing step. Then, an inflection point generated when the LED line irradiated on the concave-convex portion of the component is bent due to the irradiation angle and the relative position of the component is extracted. Thereafter, the distance between the inflection point and the inflection point is measured in order to measure the part-by-part dimension.

The part inspection apparatus can determine whether the machined part is defective by using the measured distance between the inflection points (940). Specifically, the part inspection apparatus compares the distance between the reference dimension and the measured inflection point, and it can be judged as normal if the tolerance is not exceeded. If it is determined that the defect is not normal, the process returns to step 910 and a new part can be inspected.

If it is determined in step 940 that the distance difference between the reference dimension and the measured inflection point exceeds the tolerance, it is determined to be a defective product. In this case, the stop signal may be transmitted to at least one of the CNC lathe machining part system or the transfer robot ARM (950).

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

In the embodiments described above, all of the steps may optionally be performed or omitted. Also, the steps in each embodiment need not occur in order, but may be reversed. It should be understood, however, that the embodiments herein disclosed and illustrated herein are illustrative of specific examples and are not intended to limit the scope of the present disclosure. That is, it will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are feasible.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And is not intended to limit the scope of the invention. It is to be understood by those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: Machined parts machine for CNC lathe
200: Robot arm for transfer
300: Parts inspection device

Claims (10)

Computer numerical control (CNC) In a method of inspection of parts produced by a lathe,
Obtaining a line scan image in which a light emitting diode (LED) line scan using the scan pattern is performed on the part;
Measuring a distance between at least one inflection point that is a discrepancy point between a plurality of scan lines included in the pattern among the scan patterns included in the line scan image; And
Determining whether the part is defective based on the distance between the at least one inflection points,
Wherein measuring the distance between the inflection points comprises:
Extracting edges of each scan line among the plurality of scan lines;
Obtaining a center point line of the scan line from the edges; And
And calculating an error between mismatched center-point lines among the center-point lines. 2. The method of claim 1, wherein obtaining the line scan image comprises:
Adjusting at least one of a light amount, an irradiation direction, and a time of the LED according to the type of the component;
Performing a line scan on the part according to the scan pattern; And
And performing noise removal and monochrome conversion on an image obtained from the line scan. delete 2. The method of claim 1, wherein determining whether the component is defective comprises:
And judging that the part is defective when the error between the center-point lines exceeds a reference dimension. The method of claim 1, wherein the at least one inflection point
Wherein the parts are located at the boundaries of the different heights depending on the structure of the parts. The method of claim 1,
A cross pattern or a lattice pattern. Computer numerical control (CNC) In an inspection apparatus for parts produced by a lathe,
An LED irradiating unit for irradiating a light emitting diode (LED) using the scan pattern with respect to the component;
An input unit for obtaining a line scan image of a part irradiated with an LED using the scan pattern; And
And a controller for determining whether the component is defective by using a distance between at least one inflection point that is a discrepancy point between a plurality of scan lines included in the pattern among the scan patterns included in the line scan image,
Wherein,
Wherein an edge of each scan line among the plurality of scan lines is extracted and a center line of the scan line is obtained from the edges and an error between mismatched center line lines of the center line is calculated. Device. 8. The LED lighting apparatus according to claim 7,
LED light source;
A scan pattern including a plurality of lines; And
And an extension prevention lens for preventing extension of light of the LED light source. 8. The method of claim 7,
A cross-shaped pattern or a lattice-like pattern. 8. The apparatus of claim 7, wherein the control unit
An environment variable control unit for controlling information about the LED light quantity, the irradiation direction or the time of the LED irradiation unit; And
And an image processor for removing noise from the line scan image and converting the noise into a monochrome image.

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