WO2022199235A1 - 一种曲轴主轴颈与曲柄销表面缺陷视觉检测设备及方法 - Google Patents

一种曲轴主轴颈与曲柄销表面缺陷视觉检测设备及方法 Download PDF

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Publication number
WO2022199235A1
WO2022199235A1 PCT/CN2022/072478 CN2022072478W WO2022199235A1 WO 2022199235 A1 WO2022199235 A1 WO 2022199235A1 CN 2022072478 W CN2022072478 W CN 2022072478W WO 2022199235 A1 WO2022199235 A1 WO 2022199235A1
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Prior art keywords
crankshaft
crankpin
image
main journal
crank
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PCT/CN2022/072478
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English (en)
French (fr)
Inventor
宋嘉诚
姚振强
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上海智能制造功能平台有限公司
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Publication of WO2022199235A1 publication Critical patent/WO2022199235A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
    • G01N2021/8887—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges based on image processing techniques

Definitions

  • the invention relates to the field of optical image detection, in particular to a visual detection device and method for surface defects of crankshaft main journals and crankpins.
  • the crank converts the linear reciprocating motion of the piston into rotational motion, which in turn outputs torque.
  • the main journal and the crank pin are important working areas of the crankshaft.
  • the main journal supports and constrains the crankshaft to achieve rotational movement around the axis of the main journal.
  • the crankpin connects the crankshaft and the crank and forms a crank-slider mechanism together with the piston. Therefore, on the crankshaft, the surfaces of the main journal and the crankpin are important working surfaces, and their surfaces are usually not allowed to appear cracks, corrosion and other defects. Otherwise, there will be serious wear between the crankshaft and the crankshaft and the engine block during the work of the internal combustion engine.
  • the Chinese patent with the application number of 202010005098.5 discloses a machine vision detection mechanism and detection method for engine crankshaft journal defects, including a detection room, a production line and a NG line, and a CCD detection group is installed inside the detection room.
  • the robot the mobile end of the robot is equipped with a clamping jaw assembly, the clamping jaw assembly includes a main frame, the middle part of the top wall of the main frame is connected with the mobile end of the robot, and the left and right parts of the main frame are connected.
  • a cylinder is installed on the top wall of the cylinder, and a clamping jaw is installed on the piston end of the cylinder.
  • the invention uses a CCD camera and a pneumatic stopper to stop and stop the crankshaft on the crankshaft support, and then pass the clamping jaw.
  • the combination of the components and the robot can quickly clamp the crankshaft, and use the CCD camera head and the detection port of the CCD detection group to quickly capture each journal of the crankshaft and maintain the consistency of the image.
  • the above patent requires the robot hand to grab the main journal and move it to the front of the CCD camera, and then put it back on the production line after collecting the data, which requires high speed and rhythm control of the production line.
  • the grasping and moving operations of the robot hand itself are wasted for a long time.
  • the above patent does not address the influence of the crankshaft camber factor, and only obtains approximate results by taking multiple pictures. The final defect size and morphology results will be greatly distorted.
  • the purpose of the present invention is to provide a visual inspection device and method for surface defects of crankshaft main journal and crankpin.
  • a first aspect of the present invention provides a visual inspection device for surface defects of crankshaft main journals and crankpins, including:
  • a drive end for driving the crank to be tested to rotate the drive end is arranged at one end of the crank to be tested; the drive end is provided with a first positioning device connected to one end of the crank to be tested;
  • a support end for supporting the rotation of the crank under test; the support end is arranged on the other end of the crank under test; the support end is provided with a second positioning device connected with the crank under test;
  • an image acquisition device for acquiring images of the surfaces to be measured of the crankshaft main journal and the crankpin, the image acquisition device being arranged just above the crankshaft main journal and the crankpin;
  • the first positioning device and the second positioning device respectively position and clamp the crank under test from both ends, the driving end drives the crank under test to rotate, and the image acquisition device follows the rotation of the crank under test in sequence. Acquire the local surface images of the crankshaft main journal and crankpin to be measured corresponding to the set angle, and obtain several images of the crankshaft main journal and crankpin to be measured for one rotation; and stitch the obtained images in the order of acquisition to obtain the image of the surface to be measured. , so that the complete defect morphology of the surface to be tested can be obtained.
  • the driving end includes:
  • first rotating shaft one end of the first rotating shaft is connected with the first power device, and the first power device drives the first rotating shaft to rotate;
  • a first adjusting disk one side of the first adjusting disk is connected with the other end of the first rotating shaft, the other side of the first adjusting disk is connected with the first positioning device, and the first rotating shaft rotates to drive The first adjusting disk and the first positioning device rotate; and the first positioning device can move along the side surface of the first adjusting disk, so as to adjust the distance between the first positioning device and the first rotating shaft.
  • the first positioning device is a first center, and the ejector pin end of the first center is pushed into the hole of the crankshaft; the other end of the first center is connected to the first adjustment disc through a first slider , the first sliding block can move along any position of the side surface of the first adjusting disc.
  • the support end includes:
  • a second rotating shaft one end of the second rotating shaft is connected to the equipment base through a bearing;
  • a second adjusting disk one side of the second adjusting disk is connected with the other end of the second shaft; the other side of the second adjusting disk is connected with the second positioning device; and the second positioning device It can move along the side surface of the second adjusting disc, so as to adjust the distance between the second positioning device and the second rotating shaft.
  • the second positioning device is a second center, wherein the ejector end of the second center is pushed into the hole of the crankshaft; the other end of the second center is adjusted with the second slider through the second slider
  • the disk is connected, and the second slider can move anywhere along the side surface of the second adjustment disk.
  • the visual inspection equipment for surface defects of crankshaft main journal and crankpin includes a control device, and the control device controls the image acquisition device to acquire an image every time the crank under test rotates by 1°.
  • the visual inspection equipment for surface defects of the crankshaft main journal and the crankpin further includes an image processing device, which uses image processing to analyze whether there are defects in the images of the surfaces to be tested after splicing and to determine the defect positions.
  • a second aspect of the present invention provides a visual inspection method for surface defects of crankshaft main journals and crankpins, which is carried out by using the above-mentioned visual inspection equipment for surface defects of crankshaft main journals and crankpins.
  • the visual inspection method for surface defects of crankshaft main journal and crankpin includes:
  • the image acquisition device is installed directly above the crankshaft main journal and crankpin of the crankshaft to be measured; the crankshaft to be measured is driven to rotate through the driving end; the image acquisition device sequentially acquires the crankshaft to be measured corresponding to the set angle with the rotation of the crankshaft to be measured Partial surface images of the main journal and crankpin of the crankshaft to obtain several images of the crankshaft main journal and crankpin of the crankshaft to be tested for one rotation;
  • the correspondence between the point (x', y') on the plane image and the point (x, y) of the cylindrical surface image is:
  • R is the radius of the cylinder
  • ⁇ is the central angle, here is ⁇ /180rad.
  • the present invention has at least one of the following beneficial effects:
  • the above detection device of the present invention adopts a coaxial rotary mechanism to ensure that the image acquisition device can effectively obtain the circumferential images of the crankshaft main journal and the crankpin, which solves the limitation of the focal depth of the optical detection camera;
  • the image of the tested surface can be analyzed by image processing to analyze the components in the image, efficiently analyze whether there is a defect on the tested surface, effectively determine the location of the tested surface defect, and draw the defect shape completely and clearly.
  • Fig. 1a is a schematic diagram of the image detection principle of the crankshaft main journal image by the visual inspection equipment for the surface defects of the crankshaft main journal and the crankpin according to a preferred embodiment of the present invention
  • Figure 1b is a side view of Figure 1a;
  • FIG. 2a is a schematic diagram of the image detection principle of the crankshaft crankpin image by the visual inspection equipment for the surface defects of the crankshaft main journal and the crankpin according to a preferred embodiment of the present invention
  • Figure 2b is a side view of Figure 2a
  • 2c is a schematic diagram of the image detection principle of the crankshaft crankpin image by the visual inspection equipment for the surface defects of the crankshaft main journal and the crankpin according to a preferred embodiment of the present invention
  • Figure 2d is a side view of Figure 2c
  • Fig. 3 is a preferred embodiment of the present invention, in the method for visual inspection of surface defects of crankshaft main journal and crankpin;
  • FIG. 4 is a schematic diagram of image stitching in the visual inspection method for surface defects of crankshaft main journal and crankpin according to a preferred embodiment of the present invention
  • FIG. 5 is a block diagram of image recognition of a method for visual inspection of surface defects of crankshaft main journals and crankpins according to a preferred embodiment of the present invention
  • first power unit 1 first rotating shaft 2 , first adjusting disk 3 , first top 4 , image acquisition device 5 , second top 6 , second adjusting disk 7 , and second rotating shaft 8 .
  • FIG. 1a and 1b it is a schematic diagram of the crankshaft main journal image detection by the visual inspection equipment for crankshaft main journal and crankpin surface defects according to a preferred embodiment of the present invention, including: a drive end, a support end and an image acquisition device.
  • the driving end is arranged at one end of the crank under test, and is used for driving the crank under test to rotate.
  • the driving end is provided with a first positioning device connected to one end of the crankshaft of the crank under test.
  • the support end is arranged at the other end of the crank to be tested, and plays the role of supporting the rotation of the crank to be tested; the support end is provided with a second positioning device connected to the other end of the crankshaft of the crank to be tested.
  • the image acquisition device is installed just above the crankshaft main journal to be tested and the crankpin to be tested; the surface image of the crankshaft main journal and the crankpin rotates one revolution during the rotation process is collected.
  • the image acquisition device adopts a camera.
  • the focal length of the camera should be large enough to ensure that the camera will not interfere with the crankshaft to be measured during the rotation of the shaft system.
  • the first positioning device and the second positioning device respectively locate and clamp the crank under test from both ends, the driving end drives the crank under test to rotate, and the image acquisition device acquires the entire circumferential surface image of the crankshaft main journal and the crankpin for one rotation, and captures the image of the crankshaft. All images obtained during one rotation are stitched together to obtain the image of the surface to be tested, so as to obtain the complete defect morphology.
  • the driving end includes a first power device 1 , a first rotating shaft 2 , a first adjusting disk 3 and a first positioning device.
  • the first power device 1 provides power for the rotation of the crank under test.
  • the first power device 1 adopts a servo motor.
  • One end of the first rotating shaft 2 is connected with the first power device 1 , and the first power device 1 drives the first rotating shaft 2 to rotate.
  • One side of the first adjusting disk 3 is connected with the other end of the first rotating shaft 2, the other side of the first adjusting disk 3 is connected with the first positioning device, and the rotation of the first rotating shaft 2 drives the first adjusting disk 3 and the first positioning device to rotate ; And the first positioning device can move along the side of the first adjustment plate 3, so as to adjust the distance between the first positioning device and the first rotating shaft 2.
  • the first positioning device is a first center 4, and the thimble end of the first center 4 is pushed into the hole of the crankshaft; the other end of the first center 4 passes through the first slider and the first center.
  • the adjusting disc 3 is connected, and the first sliding block can move along any position on the side of the first adjusting disc 3 .
  • the support end includes a second shaft 8 and a second adjusting disc 7 , wherein one end of the second shaft 8 is connected to the base of the testing equipment of the present invention through a bearing.
  • One side of the second adjusting disk 7 is connected with the other end of the second rotating shaft 8; the other side of the second adjusting disk 7 is connected with the second positioning device; and the second positioning device can move along the side of the second adjusting disk 7, thereby adjusting The distance between the second positioning device and the second rotating shaft 8 .
  • the second positioning device is a second center 6, wherein the ejector end of the second center 6 is pushed into the hole of the crankshaft; the other end of the second center 6 is connected with the second adjusting disc 7 through the second slider , the second sliding block can move along any position on the side of the second adjusting disc 7 .
  • the first top 4 and the second top 6 at both ends of the crankshaft will be pushed into the top holes (process holes) on both sides of the crankshaft to locate the position of the crankshaft.
  • the visual inspection equipment for surface defects of crankshaft main journal and crankpin includes a control device, and the control device controls the image acquisition device 5 to acquire an image every time the crank under test rotates by 1°.
  • the visual inspection equipment for surface defects of crankshaft main journal and crankpin includes an image processing device, which uses image processing to analyze whether there is a defect in the image of the surface to be tested after splicing and determine the defect location.
  • a visual inspection method for surface defects of crankshaft main journals and crankpins is provided, and the inspection method adopts the crankshaft described in the above embodiments.
  • Visual inspection equipment for surface defects of main journals and crank pins is provided.
  • the visual inspection method for surface defects of crankshaft main journal and crankpin includes:
  • the image acquisition device 5 is installed directly above the main journal of the crankshaft to be tested and the crankpin of the crankshaft; the crank to be tested is driven to rotate through the driving end.
  • the surfaces to be measured are all cylindrical surfaces.
  • the camera can only effectively obtain a small part of the clear image near its focal plane, and the reflective properties of the metal surface make the
  • the images obtained by direct shooting have large differences in brightness, and it is difficult to further image processing.
  • a single frame image can only clearly display a small angle range ( Figure 3), and the image within this range can be approximately regarded as a plane.
  • the image outside the range will become blurred and dim due to misalignment of focus and uneven illumination intensity.
  • the circumferential image stitching method is adopted, referring to the image stitching principle diagram shown in Figure 4; in order to facilitate the stitching of images, the camera is controlled to focus on the surface to be measured during the measurement process to take pictures, and A total of 360 pictures were taken with the shaft system rotating for one week.
  • each image only captures the clearest central band with a width of ⁇ D/360.
  • the image of this band should be in focus and ensure proper and uniform brightness within the area.
  • the 360 clearest band-shaped areas are spliced into an image with a width of ⁇ D, that is, the flattened image of the cylindrical surface of the crankshaft main journal and crankpin to be measured.
  • the band-shaped area is a cylindrical image, which is developed into a plane image by using a mathematical mapping relationship.
  • the correspondence between the point (x', y') on the plane image and the point (x, y) of the cylindrical surface image is:
  • R is the radius of the cylinder
  • ⁇ is the central angle, here is ⁇ /180rad.
  • the surface of the defect-free main journal and crank pin captured by the camera should be calibrated (indicating the gray value of the defect-free image to compare with the defect image).
  • the method is to photograph a plurality of surfaces of the main journal and crank pin that are in the same position as the surface to be tested but without defects, and flatten the images according to the above method.
  • the gray value of the defect-free surface is recorded, and the defect threshold is defined according to the shape and color of the defect.
  • the following steps can be used to acquire the surface image of the crankshaft main journal:
  • the axis of the crankshaft main journal coincides with the connecting line of the first top 4 and the second top 6 at both ends of the crankshaft, so during the measurement process, the positions of the first top 4 and the first top 4 should be adjusted to zero, that is, the first top 4 and the first top 4.
  • a center 4 and a second center 6 are located on the axes of the first rotating shaft 2 and the second rotating shaft 8 respectively.
  • the axis of the crankshaft main journal and the connecting line between the two ends of the crankshaft are parallel and eccentric.
  • the distance between the second center 6 and the second shaft 8 is equal to the distance between the axis of the main journal and the axis of the crankpin to be measured.
  • crankpin to be tested is coaxial with the rotating shaft.
  • the camera captures the surface to be measured.
  • start the servo motor to drive the entire shaft system to rotate 360° at a constant speed, and control the camera to rotate every 1° to take a picture to get 360 pictures.

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Abstract

一种曲轴主轴颈与曲柄销表面缺陷视觉检测设备及方法，包括：驱动被测曲柄转动的驱动端，驱动端设置于被测曲柄的一端；驱动端设有第一定位装置；支撑被测曲柄转动的支撑端；支撑端设置于被测曲柄的另一端；支撑端设有第二定位装置；采集待测表面图像的图像采集装置（5）；第一、二定位装置分别从两端定位并夹紧被测曲柄，驱动端驱动被测曲柄转动，图像采集装置（5）随被测曲柄转动依次获取设定角度所对应的待测曲轴主轴颈、曲柄销局部表面图像，得到待测曲轴主轴颈、曲柄销旋转一周的若干图像；将得到的若干图像按照获取顺序拼接得到待测表面的图像。高效地分析被测表面是否存在缺陷；以及有效确定被测表面缺陷位置。

Description

一种曲轴主轴颈与曲柄销表面缺陷视觉检测设备及方法 技术领域
本发明涉及光学图像检测领域，具体地，涉及一种曲轴主轴颈与曲柄销表面缺陷视觉检测设备及方法。
背景技术
在内燃机中，曲柄使活塞的直线往复运动转化为旋转运动，进而输出扭矩。主轴颈与曲柄销是曲轴的重要工作区域，主轴颈支撑并约束曲轴实现绕主轴颈轴线的旋转运动，曲柄销连接曲轴和曲柄并与活塞共同形成曲柄滑块机构。所以在曲轴上，主轴颈和曲柄销的表面是重要的工作面，其表面通常不允许出现裂纹、锈蚀等缺陷。否则，在内燃机工作工程中，曲轴和曲柄以及发动机缸体之间会出现严重的磨损。
经检索发现，申请号为202010005098.5的中国专利，公开了一种发动机曲轴轴颈缺陷的机器视觉检测机构及检测方法，包括检测室、生产线和NG线，所述检测室的内部安装有CCD检测组和机械人，所述机械人的移动端安装有夹爪组件，所述夹爪组件包括主板架，所述主板架的顶壁中部与机械人的移动端相连接，所述主板架左右两部的顶壁均安装有气缸，所述气缸的活塞端安装有夹爪，本发明通过CCD采像头和气动挡停器的使用，对曲轴支座上的曲轴进行挡停作业，再通过夹爪组件和机器人的配合，对曲轴进行快速夹持，利用CCD采像头和CCD检测组的检测口，能够快速拍摄曲轴各个轴颈并保持图像的一致性。
但是上述专利需要机器手抓取主轴颈并移动到CCD采像头前，采集完数据后再放回生产线上，对生产线的速度和节拍控制要求很高。机器手本身的抓取和移动操作都浪费了较长时间。另外，上述专利未解决曲轴弧面因素的影响，仅通过拍摄多张图片求得近似结果。最终得到的缺陷大小、形貌结果会有很大的畸变。
发明内容
针对现有技术中的缺陷，本发明的目的是提供一种曲轴主轴颈与曲柄销表面缺 陷视觉检测设备及方法。
本发明第一个方面提供一种曲轴主轴颈与曲柄销表面缺陷视觉检测设备，包括：
用于驱动被测曲柄转动的驱动端，所述驱动端设置于所述被测曲柄的一端；所述驱动端设有与所述被测曲柄一端连接的第一定位装置；
用于支撑所述被测曲柄转动的支撑端；所述支撑端设置于所述被测曲柄的另一端；所述支撑端设有与所述被测曲柄连接的第二定位装置；
用于采集曲轴主轴颈和曲柄销待测表面图像的图像采集装置，所述图像采集装置设置于所述曲轴主轴颈与所述曲柄销的正上方；
所述第一定位装置、所述第二定位装置分别从两端定位并夹紧所述被测曲柄，所述驱动端驱动所述被测曲柄转动，所述图像采集装置随被测曲柄转动依次获取设定角度所对应的待测曲轴主轴颈、曲柄销局部表面图像，得到待测曲轴主轴颈、曲柄销旋转一周的若干图像；并将得到的若干图像按照获取顺序拼接得到待测表面的图像，从而能获得待测表面完整的缺陷形貌。
优选地，所述驱动端包括：
为所述被测曲柄转动提供动力的第一动力装置；
第一转轴；所述第一转轴的一端与所述第一动力装置连接，所述第一动力装置驱动所述第一转轴转动；
第一调节盘；所述第一调节盘一侧与所述第一转轴的另一端连接，所述第一调节盘的另一侧面与所述第一定位装置连接，所述第一转轴转动带动所述第一调节盘及所述第一定位装置转动；且所述第一定位装置能沿所述第一调节盘侧面移动，从而调节所述第一定位装置与所述第一转轴的距离。
优选地，所述第一定位装置为第一顶尖，所述第一顶尖的顶针端顶入曲轴的孔中；所述第一顶尖的另一端通过第一滑块与所述第一调节盘连接，所述第一滑块能沿所述第一调节盘侧面的任意位置移动。
优选地，所述支撑端包括：
第二转轴；所述第二转轴的一端通过轴承连接于设备基座上；
第二调节盘；所述第二调节盘一侧面与所述第二转轴的另一端连接；所述第二调节盘的另一侧面与所述第二定位装置连接；且所述第二定位装置能沿所述第二调节盘侧面移动，从而调节所述第二定位装置与所述第二转轴的距离。
优选地，所述第二定位装置为第二顶尖，其中，所述第二顶尖的顶针端顶入曲轴的孔中；所述第二顶尖的另一端通过第二滑块与所述第二调节盘连接，所述第二滑块能沿所述第二调节盘侧面的任意位置移动。
优选地，曲轴主轴颈与曲柄销表面缺陷视觉检测设备包括控制装置，所述控制装置控制所述图像采集装置当所述被测曲柄每转动1°时获取一张图像。
优选地，曲轴主轴颈与曲柄销表面缺陷视觉检测设备还包括图像处理装置，采用图像处理分析拼接后待测表面的图像是否存在缺陷以及确定缺陷位置。
本发明第二个方面提供一种曲轴主轴颈与曲柄销表面缺陷视觉检测方法，采用上述所述的曲轴主轴颈与曲柄销表面缺陷视觉检测设备进行。
优选地，曲轴主轴颈与曲柄销表面缺陷视觉检测方法，包括：
将图像采集装置安装于待测曲轴主轴颈、曲轴曲柄销的正上方；通过驱动端驱动被测曲柄转动；所述图像采集装置随被测曲柄曲轴转动依次获取设定角度所对应的待测曲轴主轴颈、曲轴曲柄销局部表面图像，得到待测曲轴主轴颈、曲轴曲柄销旋转一周的若干图像；
截取每张图像的中间最清晰的宽度为πD/360的带状区域，其中D指待测曲轴主轴颈、曲轴曲柄销的直径；并按照获得顺序将所有带状区域拼接成宽度为πD的图像，即待测曲轴主轴颈、曲轴曲柄销圆柱形表面的展平图像；
对得到展平图像进行中值滤波去除图像中的噪声，之后对图像进行灰度处理，得到表面各个区域的灰度值；对图像采集装置获取的图像进行校准，即获取多个无缺陷表面并记录无缺陷表面的灰度值；根据缺陷的形貌及颜色定义缺陷阈值；当测得的某一表面区域的灰度值与无缺陷表面的平均灰度值偏差大于缺陷阈值时，则该区域为缺陷区域。
优选地，平面图像上的点(x’,y’)与圆柱表面图像点(x,y)的对应关系为：
Figure PCTCN2022072478-appb-000001
其中R为圆柱半径，
Figure PCTCN2022072478-appb-000002
α为圆心角，此处为π/180rad。
与现有技术相比，本发明具有如下至少一种的有益效果：
本发明上述检测设备，采用同轴回转机构保证图像采集装置能够有效地获得曲 轴主轴颈与曲柄销周向图像，解决了光学检测相机存在焦深的限制；并对采集周向图像进行拼接得到被测表面的图像，可通过图像处理来分析图像中的成分，高效地分析被测表面是否存在缺陷；有效确定被测表面缺陷位置；完整清晰地绘制缺陷形貌。
附图说明
通过阅读参照以下附图对非限制性实施例所作的详细描述，本发明的其它特征、目的和优点将会变得更明显：
图1a是本发明一优选实施例的曲轴主轴颈与曲柄销表面缺陷视觉检测设备对曲轴主轴颈图像检测原理图；
图1b是图1a的侧视图；
图2a是本发明一优选实施例的曲轴主轴颈与曲柄销表面缺陷视觉检测设备对曲轴曲柄销图像检测原理图；
图2b是图2a的侧视图；
图2c是本发明一优选实施例的曲轴主轴颈与曲柄销表面缺陷视觉检测设备对曲轴曲柄销图像检测原理图；
图2d是图2c的侧视图；
图3是本发明一优选实施例的曲轴主轴颈与曲柄销表面缺陷视觉检测方法中圆柱表面拍摄清晰带；
图4是本发明一优选实施例的曲轴主轴颈与曲柄销表面缺陷视觉检测方法中图像拼接原理图；
图5是本发明一优选实施例的曲轴主轴颈与曲柄销表面缺陷视觉检测方法的图像识别的模块图；
图中标记分别表示为：第一动力装置1、第一转轴2、第一调节盘3、第一顶尖4、图像采集装置5、第二顶尖6、第二调节盘7、第二转轴8。
具体实施方式
下面结合具体实施例对本发明进行详细说明。以下实施例将有助于本领域的技术人员进一步理解本发明，但不以任何形式限制本发明。应当指出的是，对本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进。这些都属于 本发明的保护范围。
参照图1a、图1b所示，为本发明一优选实施例的曲轴主轴颈与曲柄销表面缺陷视觉检测设备对曲轴主轴颈图像检测原理图，包括：驱动端、支撑端和图像采集装置。
其中，驱动端设置于被测曲柄的一端，用于驱动被测曲柄转动。驱动端设有与被测曲柄的曲轴一端连接的第一定位装置。
支撑端设置于被测曲柄的另一端，起到支撑被测曲柄转动的作用；支撑端设有与被测曲柄的曲轴另一端连接的第二定位装置。
图像采集装置安装在待测曲轴主轴颈和待测曲柄销的正上方；采集转动过程中曲轴主轴颈与曲柄销旋转一周的表面图像。作为一优选方式，图像采集装置采用相机。相机的焦距应足够大以保证轴系旋转过程中相机不会和被测曲轴干涉。
第一定位装置、第二定位装置分别从两端定位并夹紧被测曲柄，驱动端驱动被测曲柄转动，图像采集装置获取曲轴主轴颈与曲柄销旋转一周的整个周向表面图像，并将获取的旋转一周所有图像拼接得到待测表面的图像，从而获得完整的缺陷形貌。
在其他部分优选实施例中，参照图1a所示，驱动端包括第一动力装置1、第一转轴2、第一调节盘3和第一定位装置。其中，第一动力装置1为被测曲柄转动提供动力。作为一优选方式，第一动力装置1采用伺服电机。
第一转轴2的一端与第一动力装置1连接，第一动力装置1驱动第一转轴2转动。
第一调节盘3一侧与第一转轴2的另一端连接，第一调节盘3的另一侧面与第一定位装置连接，第一转轴2转动带动第一调节盘3及第一定位装置转动；且第一定位装置能沿第一调节盘3侧面移动，从而调节第一定位装置与第一转轴2的距离。
作为一优选方式，参照图1a所示，第一定位装置为第一顶尖4，第一顶尖4的顶针端顶入曲轴的孔中；第一顶尖4的另一端通过第一滑块与第一调节盘3连接，第一滑块能沿第一调节盘3侧面的任意位置移动。
在其他部分优选实施例中，参照图1a所示，支撑端包括第二转轴8和第二调节盘7，其中，第二转轴8的一端通过轴承连接于本发明的检测设备基座上。
第二调节盘7一侧面与第二转轴8的另一端连接；第二调节盘7的另一侧面与第二定位装置连接；且第二定位装置能沿第二调节盘7侧面移动，从而调节第二定位装置与第二转轴8的距离。
作为一优选方式，第二定位装置为第二顶尖6，其中，第二顶尖6的顶针端顶入曲轴的孔中；第二顶尖6的另一端通过第二滑块与第二调节盘7连接，第二滑块能沿第二调 节盘7侧面的任意位置移动。
在测量过程中，将曲轴两端的第一顶尖4、第二顶尖6将顶入曲轴两侧的顶尖孔(工艺孔)内来定位曲轴的位置。
在其他部分优选实施例中，曲轴主轴颈与曲柄销表面缺陷视觉检测设备包括控制装置，控制装置控制图像采集装置5当被测曲柄每转动1°时获取一张图像。
在其他部分优选实施例中，曲轴主轴颈与曲柄销表面缺陷视觉检测设备包括图像处理装置，采用图像处理分析拼接后待测表面的图像是否存在缺陷以及确定缺陷位置。
在另一实施例中，基于上述曲轴主轴颈与曲柄销表面缺陷视觉检测设备的结构特征，提供一种曲轴主轴颈与曲柄销表面缺陷视觉检测方法，该检测方法采用上述实施例所述的曲轴主轴颈与曲柄销表面缺陷视觉检测设备进行。
在其他部分优选实施例中，曲轴主轴颈与曲柄销表面缺陷视觉检测方法包括：
将图像采集装置5安装于待测曲轴主轴颈、曲轴曲柄销的正上方；通过驱动端驱动被测曲柄转动。
待测表面(主轴颈、曲柄销表面)均为圆柱形表面，在使用相机进行拍摄时，相机只能有效地得到其焦平面附近的很小一部分的清晰图像，并且金属材质表面的反光特性使得直接拍摄得到的图像亮度差异大，很难进一步进行图像处理。单帧图像只能清晰显示很小的角度范围(图3)，在这个范围内的图像可近似看作平面。当待测表面出现周向裂纹或锈蚀缺陷时，范围外的图像因焦距不对准和光照强度不均匀的问题，图像将变得模糊且昏暗。为了得到完整的缺陷形貌，采用了周向图像拼接方法，参照图4所示的图像拼接原理图；为了方便进行图像的拼接，测量过程中控制相机聚焦在待测表面正上方进行拍照，并随轴系转动一周共拍摄360张图片。
对于直径为D的圆柱形表面，每张图片只截取中间最清晰的宽度为πD/360的带状区域。该带状区域的图像应该被准确对焦并且保证区域内亮度合适并均一。并按拍摄顺序将360个最清晰的带状区域拼接成宽度为πD的图像，即曲轴主轴颈、曲轴曲柄销待测圆柱形表面的展平图像。
作为一优选方式，带状区域为圆柱图像，利用数学映射关系将其展为平面图像。平面图像上的点(x’,y’)与圆柱表面图像点(x,y)的对应关系为：
Figure PCTCN2022072478-appb-000003
其中R为圆柱半径，
Figure PCTCN2022072478-appb-000004
α为圆心角，此处为π/180rad。
参照图5所示，得到展平图像之后，先对图像进行中值滤波去除图像中的噪声，之后对图像进行灰度处理，得到表面各个区域的灰度。在正式测量之前，应该对相机拍摄到的无缺陷主轴颈、曲柄销的表面进行标定(指标定无缺陷图像的灰度值，以与缺陷图像作比较)。方法是拍摄多个与待测表面相同位置但无缺陷的主轴颈、曲柄销表面，按照上述方法进行图像展平。记录无缺陷表面的灰度值，并根据缺陷的形貌及颜色定义缺陷阈值。当待测表面的展平图像上的某一区域的灰度与无缺陷表面平均灰度偏差大于该阈值时，则定义该区域为缺陷区域。
在一优选实施例中，采集曲轴主轴颈表面图像可以采用以下步骤：
参照图1所示，曲轴主轴颈轴线与曲轴两端第一顶尖4、第二顶尖6连线重合，所以在测量过程中应调整第一顶尖4、第一顶尖4的位置至零点，即第一顶尖4、第二顶尖6位置分别在第一转轴2、第二转轴8轴线上。调整好第一顶尖4、第二顶尖6位置后，用第一顶尖4、第二顶尖6定位并夹紧被测曲轴；之后将相机放置在待测主轴颈上方，调整焦距使相机聚焦在待测主轴颈与相机最近的正上方；最后，启动伺服电机匀速驱动整个轴系转动360°，并控制相机每隔转系转动1°拍摄一张图片得到360张图片。
采集曲轴曲柄销表面图像可以采用以下步骤：
结合图2a、图2b、图2c及图2d所示，曲轴主轴颈轴线与曲轴两端连线平行且有偏心，所以在测量过程中调整顶尖使第一顶尖4与第一转轴2之间、第二顶尖6与第二转轴8之间的距离等于主轴颈轴线与待测曲柄销轴线之间的距离。调整好顶尖位置后，装夹被测曲轴使待测曲柄销轴线相对于主轴颈轴线的方向与顶尖调节方向相反，参照图2a、图2b所示，用双顶尖定位并夹紧被测曲轴。由于两端顶尖连线与主轴颈同轴，按上述方法调整完距离和方向后即可保证待测曲柄销与转轴是同轴。在旋转测量过程中，相机可以拍到待测表面。之后，将相机放置在待测曲柄销上方，调整焦距使相机聚焦在待测曲柄销与相机最近的正上方。最后，启动伺服电机匀速驱动整个轴系转动360°，并控制相机每隔转系转动1°拍摄一张图片得到360张图片。
以上对本发明的具体实施例进行了描述。需要理解的是，本发明并不局限于上述特定实施方式，本领域技术人员可以在权利要求的范围内做出各种变形或修改，这并不影响本发明的实质。

Claims (10)

  1. 一种曲轴主轴颈与曲柄销表面缺陷视觉检测设备，其特征在于，包括：
    用于驱动被测曲柄转动的驱动端，所述驱动端设置于所述被测曲柄的一端；所述驱动端设有与所述被测曲柄一端连接的第一定位装置；
    用于支撑所述被测曲柄转动的支撑端；所述支撑端设置于所述被测曲柄的另一端；所述支撑端设有与所述被测曲柄连接的第二定位装置；
    用于采集曲轴主轴颈和曲柄销待测表面图像的图像采集装置，所述图像采集装置设置于所述曲轴主轴颈与所述曲柄销的正上方；
    所述第一定位装置、所述第二定位装置分别从两端定位并夹紧所述被测曲柄，所述驱动端驱动所述被测曲柄转动，所述图像采集装置随被测曲柄转动依次获取设定角度所对应的待测曲轴主轴颈、曲柄销局部表面图像，得到待测曲轴主轴颈、曲柄销旋转一周的若干图像；并将得到的若干图像按照获取顺序拼接得到待测表面的图像，从而能获得待测表面完整的缺陷形貌。
  2. 根据权利要求1所述的曲轴主轴颈与曲柄销表面缺陷视觉检测设备，其特征在于，所述驱动端包括：
    为所述被测曲柄转动提供动力的第一动力装置；
    第一转轴；所述第一转轴的一端与所述第一动力装置连接，所述第一动力装置驱动所述第一转轴转动；
    第一调节盘；所述第一调节盘一侧与所述第一转轴的另一端连接，所述第一调节盘的另一侧面与所述第一定位装置连接，所述第一转轴转动带动所述第一调节盘及所述第一定位装置转动；且所述第一定位装置能沿所述第一调节盘侧面移动，从而调节所述第一定位装置与所述第一转轴的距离。
  3. 根据权利要求2所述的曲轴主轴颈与曲柄销表面缺陷视觉检测设备，其特征在于，所述第一定位装置为第一顶尖，所述第一顶尖的顶针端顶入曲轴的孔中；所述第一顶尖的另一端通过第一滑块与所述第一调节盘连接，所述第一滑块能沿所述第一调节盘侧面的任意位置移动。
  4. 根据权利要求2所述的曲轴主轴颈与曲柄销表面缺陷视觉检测设备，其特征在于，所述支撑端包括：
    第二转轴；所述第二转轴的一端通过轴承连接于设备基座上；
    第二调节盘；所述第二调节盘一侧面与所述第二转轴的另一端连接；所述第二调节盘的另一侧面与所述第二定位装置连接；且所述第二定位装置能沿所述第二调节盘侧面移动，从而调节所述第二定位装置与所述第二转轴的距离。
  5. 根据权利要求4所述的曲轴主轴颈与曲柄销表面缺陷视觉检测设备，其特征在于，所述第二定位装置为第二顶尖，其中，所述第二顶尖的顶针端顶入曲轴的孔中；所述第二顶尖的另一端通过第二滑块与所述第二调节盘连接，所述第二滑块能沿所述第二调节盘侧面的任意位置移动。
  6. 根据权利要求1所述的曲轴主轴颈与曲柄销表面缺陷视觉检测设备，其特征在于，还包括控制装置，所述控制装置控制所述图像采集装置当所述被测曲柄每转动1°时获取一张图像。
  7. 根据权利要求1所述的曲轴主轴颈与曲柄销表面缺陷视觉检测设备，其特征在于，还包括图像处理装置，采用图像处理分析拼接后待测表面的图像是否存在缺陷以及确定缺陷位置。
  8. 一种曲轴主轴颈与曲柄销表面缺陷视觉检测方法，其特征在于，采用上述权利要求1-7任一项所述的曲轴主轴颈与曲柄销表面缺陷视觉检测设备进行。
  9. 根据权利要求8所述的曲轴主轴颈与曲柄销表面缺陷视觉检测方法，其特征在于，包括：
    将图像采集装置安装于待测曲轴主轴颈、曲轴曲柄销的正上方；通过驱动端驱动被测曲柄转动；所述图像采集装置随被测曲柄曲轴转动依次获取设定角度所对应的待测曲轴主轴颈、曲轴曲柄销局部表面图像，得到待测曲轴主轴颈、曲轴曲柄销旋转一周的若干图像；
    截取每张图像的中间最清晰的宽度为πD/360的带状区域，其中D指待测曲轴主轴颈、曲轴曲柄销的直径；并按照获得顺序将所有带状区域拼接成宽度为πD的图像，即待测曲轴主轴颈、曲轴曲柄销圆柱形表面的展平图像；
    对得到展平图像进行中值滤波去除图像中的噪声，之后对图像进行灰度处理，得到表面各个区域的灰度值；对图像采集装置获取的图像进行校准，即获取多个无缺陷表面并记录无缺陷表面的灰度值；根据缺陷的形貌及颜色定义缺陷阈值；当测得的某一表面区域的灰度值与无缺陷表面的平均灰度值偏差大于缺陷阈值时，则该区域为缺陷区域。
  10. 根据权利要求9所述的曲轴主轴颈与曲柄销表面缺陷视觉检测方法，其特征在于，平面图像上的点(x’,y’)与圆柱表面图像点(x,y)的对应关系为：
    Figure PCTCN2022072478-appb-100001
    其中R为圆柱半径，
    Figure PCTCN2022072478-appb-100002
    α为圆心角，α＝π/180rad。
PCT/CN2022/072478 2021-03-24 2022-01-18 一种曲轴主轴颈与曲柄销表面缺陷视觉检测设备及方法 WO2022199235A1 (zh)

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