短路过渡MAG焊熔池形状参数的视觉检测
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摘要
随着焊接自动化的发展,对在线质量检测提出更高的要求。而焊接过程中焊接熔池包含较为丰富和直接的焊接质量信息,熔池的形状参数是判断焊缝成形和内在质量的重要依据。利用视觉检测获取熔池的形状参数对于验证焊接热过程数值模拟结果、实现焊接质量在线检测以及焊接熔透控制有重要的理论意义和工程实用价值。
本文针对弧光、飞溅以及烟尘等干扰因素较多的短路过渡MAG焊接过程,构建了相应的熔池视觉检测系统。基于电弧光谱分析,选择了复合滤光器,减弱了弧光的干扰。设置CCD摄像机曝光时间,设计了短路过渡信号的获取及CCD摄像机外触发电路,准确地将CCD摄像机的曝光时刻定位于短路过渡阶段,从而克服了不同时刻采集亮度不同、飞溅等干扰较多的问题。提出了正前方小角度和正后方大角度的采集方式,采用普通工业CCD摄像机拍摄到了连续清晰且不失真的熔池图像。
通过分析焊接熔池区图像,设计了7×7方形中值滤波算法,利用改进的梯度法设计了边缘增强算法,选择了边缘点的动态搜索算法,从而得到完整的熔池边缘,利用针孔模型对摄像机进行标定,实现对熔池几何参数的提取。
对采集到的不同焊接电流、焊接速度以及喷嘴高度情况下的熔池图像进行了熔池长度、熔池宽度以及宽长比等几何参数的提取,分析了熔透情况、熔池几何参数与工艺参数间的变化规律。
结合熔池侧面检测的结果,分析熔池正面检测时熔池长度结果存在较大误差的原因,并提取侧面图像中熔池倾斜度对正面检测结果进行修正,最后提出了采用以正面检测为主并综合侧面检测结果的熔池检测方案。
With the development of welding process automation, a higher demand is expected on the on-line quality monitoring. Since the weld pool contains explicit and abundant information about the welding quality, the geometry of the weld pool has a great effect on the formation and quality of the welded joint. Detecting the weld pool geometrical parameters from topside of work piece with visual sensor is of great theoretical and practical significance in verifying the numerical simulation results of welding thermal process, realizing the on-line quality monitoring and controlling weld penetration.
According to the MAG welding of short-circuiting transfer process in which arc light, spatter, smoke dust and other interference exist, a visual-based sensing system is designed. Through the analysis of the arc spectrum, a composite light-filter is determined to eliminate the disturbance of the arc light. A proper sampling time is selected. A short-circuit detection and CCD camera ex-trigger circuit is developed based on the welding voltage waveform. The exposure time is fixed at the moment of short circuit, which solves the problems caused by the surrounding luminance and spatter interference. Grabbed from the front position with small angle and the rear position with large angle, uninterrupted, clear and undistorted images of weld pool are obtained using the ordinary industrial CCD camera.
Based on the analysis of the weld pool images, a series of image processing algorithms are developed to extract the whole weld pool edge, including the 7×7 square median filtering, edge-enhanced algorithm and dynamic searching algorithm. According to the calibration result of the pinhole camera, the geometrical parameters of weld pool are acquired.
The weld pool geometrical parameters including the length, the width and the breadth length ratio are acquired under different welding current, welding speed and contact tube-to-workpiece. The regularity with the welding parameters, the weld pool geometry and weld penetration changing respectively is analyzed.
Combined with the weld pool images captured from the side direction, the reason that causes error in the weld pool length obtained from the topside sensing is analyzed. The original measurement is modified based on the weld pool gradient. A new method that the topside sensing is combined with the results acquired from the side detection is adopted
本文针对弧光、飞溅以及烟尘等干扰因素较多的短路过渡MAG焊接过程,构建了相应的熔池视觉检测系统。基于电弧光谱分析,选择了复合滤光器,减弱了弧光的干扰。设置CCD摄像机曝光时间,设计了短路过渡信号的获取及CCD摄像机外触发电路,准确地将CCD摄像机的曝光时刻定位于短路过渡阶段,从而克服了不同时刻采集亮度不同、飞溅等干扰较多的问题。提出了正前方小角度和正后方大角度的采集方式,采用普通工业CCD摄像机拍摄到了连续清晰且不失真的熔池图像。
通过分析焊接熔池区图像,设计了7×7方形中值滤波算法,利用改进的梯度法设计了边缘增强算法,选择了边缘点的动态搜索算法,从而得到完整的熔池边缘,利用针孔模型对摄像机进行标定,实现对熔池几何参数的提取。
对采集到的不同焊接电流、焊接速度以及喷嘴高度情况下的熔池图像进行了熔池长度、熔池宽度以及宽长比等几何参数的提取,分析了熔透情况、熔池几何参数与工艺参数间的变化规律。
结合熔池侧面检测的结果,分析熔池正面检测时熔池长度结果存在较大误差的原因,并提取侧面图像中熔池倾斜度对正面检测结果进行修正,最后提出了采用以正面检测为主并综合侧面检测结果的熔池检测方案。
With the development of welding process automation, a higher demand is expected on the on-line quality monitoring. Since the weld pool contains explicit and abundant information about the welding quality, the geometry of the weld pool has a great effect on the formation and quality of the welded joint. Detecting the weld pool geometrical parameters from topside of work piece with visual sensor is of great theoretical and practical significance in verifying the numerical simulation results of welding thermal process, realizing the on-line quality monitoring and controlling weld penetration.
According to the MAG welding of short-circuiting transfer process in which arc light, spatter, smoke dust and other interference exist, a visual-based sensing system is designed. Through the analysis of the arc spectrum, a composite light-filter is determined to eliminate the disturbance of the arc light. A proper sampling time is selected. A short-circuit detection and CCD camera ex-trigger circuit is developed based on the welding voltage waveform. The exposure time is fixed at the moment of short circuit, which solves the problems caused by the surrounding luminance and spatter interference. Grabbed from the front position with small angle and the rear position with large angle, uninterrupted, clear and undistorted images of weld pool are obtained using the ordinary industrial CCD camera.
Based on the analysis of the weld pool images, a series of image processing algorithms are developed to extract the whole weld pool edge, including the 7×7 square median filtering, edge-enhanced algorithm and dynamic searching algorithm. According to the calibration result of the pinhole camera, the geometrical parameters of weld pool are acquired.
The weld pool geometrical parameters including the length, the width and the breadth length ratio are acquired under different welding current, welding speed and contact tube-to-workpiece. The regularity with the welding parameters, the weld pool geometry and weld penetration changing respectively is analyzed.
Combined with the weld pool images captured from the side direction, the reason that causes error in the weld pool length obtained from the topside sensing is analyzed. The original measurement is modified based on the weld pool gradient. A new method that the topside sensing is combined with the results acquired from the side detection is adopted
引文
1。 吕学勤,张轲,吴毅雄.焊缝自动跟踪的发展现状与展望[J].机械工程学报,2003,39(12):80-85
2.Sukhomay Pal.Artificial neural network modeling of weld joint strength prediction of a pulsed metal inert gas welding process using arc signal[J].Journal of Materials Processing Technology.2007 Article in Press.
3.林尚扬。焊接机器人及其应用[M].北京:机械工业出版社,2000
4.殷树言。气体保护焊工艺基础[M]。北京:机械工业出版社,2007
5.Bob Irving.Sensor and Control Continue to Close the Loop in Arc Welding[J].Welding Journal.1999,78(5):31-36
6。 王春明.激光焊接质量实时检测技术的研究现状[J].电焊机,2005,35(7):18-22
7.Ladislav Grad,Feasibility study of acoustic signals for on-line monitoring in short circuit gas metal arc welding[J].International Journal of Machine Tools &Manufacture.2004:555-561
8.Gu H,Duley W W.Statistical approach to acoustic monitoring of laser welding[J].Phys.1996,(29):556-560
9。 王其隆.弧焊过程质量实时传感与控制[M].北京:机械工业出版社,2000
10.A.Bicknell,J.S Smith,J.Lucas.Arc voltage sensor for monitoring of penetration in TIG welds[J].IEE Proc.Science,Measurement and Technology.1994,141(6):513-520
11.潘际銮.现代弧焊控制[M]。北京:机械工业出版社,2000
12.P.U.Dilthey,J.Gollnick.Through the arc Sensing in GMA-Welding with high speed rotating torch[J].Industrial Electronics Society,1998.IECON '98.Proc.of the 24th Annual Conference of the IEEE.1998,4(4):2374-2377
13.D.Barborak,C.Conrardy,B.Madigan,T.Paskell.Through-arc process monitoring technique for control of automated gas metal arc welding[J].Proc.1999 IEEE ICRA.1999,4:3053-3058
14.K.Ohshima,S.Yamane,M.Yabe,K.Akita,K.Kugai,T.Kubota.Controlling of torch attitude and seam tracking using neuro arc sensor[J].Proc.of the 1995 IEEE IECON 21st International Conference on Industrial Electronics,Control,and Instrumentation.1995,2(2):1185-1189
15.S.K.Jeong,G.Y.Lee,W.K.Lee,S.B.Kim.Development of high speed rotating arc sensor and seam tracking controller for welding robots[J].Proc.of IEEE International Symposium on Industrial Electronics.2001,2:845-850
16.K.Anderson,G.E.Cook,R.J.Barnett,A.M.Strauss.Synchronous weld pool oscillation for monitoring and control[J].Industry Applications Society Annual Meeting,1994,Conference Record of the 1994 IEEE.1994,3:1906-1913
17.Y.H.Xiao and G.Den.Ouden.A study of GTA weld pool oscillation[J].Welding Journal.1990,69(8):289-293
18.杨春利.薄钢板TIG焊电弧传感熔池谐振法熔透实时控制[J].哈尔滨工业大学博士学位论文,1991
19.董春林.不锈钢等离子弧焊熔池小孔行为的弧光传感研究[J].机械工程学报, 1999,35(6):48-51
20.杨春利.TIG焊变频电流下熔池谐振检测与研究[J].焊接学报,2000,21(2):6-9
21.陈定华,吴林,徐庆鸿.微计算机测定焊接温度场的研究[J].哈尔滨工业大学学报,1981,No.12:1-11
22.R.-S.Huang,Infrared temperature measurement and interference analysis of magnesium alloys in hybrid laser-TIG welding process[J].Materials Science and Engineering A 447(2007):239-243
23.吕云飞.脉冲GMAW焊接电参数波形及熔滴过渡图像的同步在线检测[D].山东大学硕士学位论文,2005
24。陈武柱CO_2激光焊同轴视觉系统及熔透状态检测的研究[J].应用激光,200424(3):130-134
25。高进强.不锈钢复合板(管)的焊接生产[R].天津大学博士后研究工作报告,2005
26.Y.M.Zhang,L.Li and R.Kovacevic.Monitoring of weld pool appearance for penetration control[J].Proceedings of the 4th International Conference on Trends in Welding Research.Gatlinburg,Tennessee.USA,June,1995
27.R.Kovacevic,Y.M.Zhang and L.Li.Monitoring of weld joint penetration based on weld pool geometrical appearance[J].Welding Journal,1996,75(10)
28.张敏.GMAW焊接熔池的激光频闪视觉检测[D].山东大学硕士学位论文,2002
29.Y.M.Zhang,R.Kovacevic.Real-time sensing of sag geometry during GTA welding [J].Journal of Manufacturing Science and Engineering,1997,119:151-160
30.Kovacevic R,Zhang Y.M.Vision sensing of 3D weld pool surface[J].Proceedings of the 4th International Conference on Trends in Welding Research,Gatlinburg,Tennessee,USA,5-8,June,1995
31.R.Kovacevic and Y.M.Zhang.Sensing free surface of arc weld pool using specular reflection:principle and analysis[J].Journal of Manufacturing Science and Engineering,1996,B210.553-564
32.R.Kovacevic and Y.M.Zhang.Real-time image processing for monitoring of free weld pool surface[J].Journal of Manufacturing Science and Engineering,1997,119:161-169
33。高进强.恒流TIG焊接熔池形状参数的视觉检测及智能控制[D].山东大学博士学位论文,2000
34.李鹏九,焊接过程弧光传感的应用基础研究[D].哈尔滨工业大学博士学位论文,1997
35.王克鸿。富氩气保焊熔池信息视觉检测方法试验研究[J].机械工程学报,2004.40(6):161-164
36.闫志鸿.脉沖熔化极气体保护焊接焊接熔池图像的检测与处理[J].焊接学报,2005.26(2):37-40
37.王克争等.MIG焊接熔池的图像处理和数字控制系统[J].清华大学学报,1990.30(2).23-26
38.R.Niepold and F.Bruemmer.Optical sensor system controls arc welding process[J].International Conference on Robots Vision and Sensor Controls,1982
39.Zhenguo Sun.A novel visual image sensor for CO2 short circuiting arc welding and its application in weld reinforcement detection[J].Meas.Sci.Technol,2006(17):1-9
40.曹一鹏.CO_2短路过渡焊接熔池图像传感器[J]。焊接学报,2004.25(2):1-4
41。王庆有.图像传感器应用技术[M].北京:电子工业出版社,2003
42.杨淑莹.VC++图像处理程序设计[M].北京:清华大学出版社,2005
43.孙即祥.图像处理[M]。北京:科学出版社,2004
44.贾云德。机器视觉[M].北京:科学出版社,2000
45.张广军。机器视觉[M].北京:科学出版社,2000
46.CMES。焊接手册[M].北京:机械工业出版社,1995
47。孙俊生.电弧热流与熔滴热焓量分布模式对熔池行为的影响[D].山东工业大学博士学位论文,1998
48.M.C.Tsai.Electromagnetic force induced convection in weld pools with a free surface[J].Welding Journal,1990,69(6):241-234
2.Sukhomay Pal.Artificial neural network modeling of weld joint strength prediction of a pulsed metal inert gas welding process using arc signal[J].Journal of Materials Processing Technology.2007 Article in Press.
3.林尚扬。焊接机器人及其应用[M].北京:机械工业出版社,2000
4.殷树言。气体保护焊工艺基础[M]。北京:机械工业出版社,2007
5.Bob Irving.Sensor and Control Continue to Close the Loop in Arc Welding[J].Welding Journal.1999,78(5):31-36
6。 王春明.激光焊接质量实时检测技术的研究现状[J].电焊机,2005,35(7):18-22
7.Ladislav Grad,Feasibility study of acoustic signals for on-line monitoring in short circuit gas metal arc welding[J].International Journal of Machine Tools &Manufacture.2004:555-561
8.Gu H,Duley W W.Statistical approach to acoustic monitoring of laser welding[J].Phys.1996,(29):556-560
9。 王其隆.弧焊过程质量实时传感与控制[M].北京:机械工业出版社,2000
10.A.Bicknell,J.S Smith,J.Lucas.Arc voltage sensor for monitoring of penetration in TIG welds[J].IEE Proc.Science,Measurement and Technology.1994,141(6):513-520
11.潘际銮.现代弧焊控制[M]。北京:机械工业出版社,2000
12.P.U.Dilthey,J.Gollnick.Through the arc Sensing in GMA-Welding with high speed rotating torch[J].Industrial Electronics Society,1998.IECON '98.Proc.of the 24th Annual Conference of the IEEE.1998,4(4):2374-2377
13.D.Barborak,C.Conrardy,B.Madigan,T.Paskell.Through-arc process monitoring technique for control of automated gas metal arc welding[J].Proc.1999 IEEE ICRA.1999,4:3053-3058
14.K.Ohshima,S.Yamane,M.Yabe,K.Akita,K.Kugai,T.Kubota.Controlling of torch attitude and seam tracking using neuro arc sensor[J].Proc.of the 1995 IEEE IECON 21st International Conference on Industrial Electronics,Control,and Instrumentation.1995,2(2):1185-1189
15.S.K.Jeong,G.Y.Lee,W.K.Lee,S.B.Kim.Development of high speed rotating arc sensor and seam tracking controller for welding robots[J].Proc.of IEEE International Symposium on Industrial Electronics.2001,2:845-850
16.K.Anderson,G.E.Cook,R.J.Barnett,A.M.Strauss.Synchronous weld pool oscillation for monitoring and control[J].Industry Applications Society Annual Meeting,1994,Conference Record of the 1994 IEEE.1994,3:1906-1913
17.Y.H.Xiao and G.Den.Ouden.A study of GTA weld pool oscillation[J].Welding Journal.1990,69(8):289-293
18.杨春利.薄钢板TIG焊电弧传感熔池谐振法熔透实时控制[J].哈尔滨工业大学博士学位论文,1991
19.董春林.不锈钢等离子弧焊熔池小孔行为的弧光传感研究[J].机械工程学报, 1999,35(6):48-51
20.杨春利.TIG焊变频电流下熔池谐振检测与研究[J].焊接学报,2000,21(2):6-9
21.陈定华,吴林,徐庆鸿.微计算机测定焊接温度场的研究[J].哈尔滨工业大学学报,1981,No.12:1-11
22.R.-S.Huang,Infrared temperature measurement and interference analysis of magnesium alloys in hybrid laser-TIG welding process[J].Materials Science and Engineering A 447(2007):239-243
23.吕云飞.脉冲GMAW焊接电参数波形及熔滴过渡图像的同步在线检测[D].山东大学硕士学位论文,2005
24。陈武柱CO_2激光焊同轴视觉系统及熔透状态检测的研究[J].应用激光,200424(3):130-134
25。高进强.不锈钢复合板(管)的焊接生产[R].天津大学博士后研究工作报告,2005
26.Y.M.Zhang,L.Li and R.Kovacevic.Monitoring of weld pool appearance for penetration control[J].Proceedings of the 4th International Conference on Trends in Welding Research.Gatlinburg,Tennessee.USA,June,1995
27.R.Kovacevic,Y.M.Zhang and L.Li.Monitoring of weld joint penetration based on weld pool geometrical appearance[J].Welding Journal,1996,75(10)
28.张敏.GMAW焊接熔池的激光频闪视觉检测[D].山东大学硕士学位论文,2002
29.Y.M.Zhang,R.Kovacevic.Real-time sensing of sag geometry during GTA welding [J].Journal of Manufacturing Science and Engineering,1997,119:151-160
30.Kovacevic R,Zhang Y.M.Vision sensing of 3D weld pool surface[J].Proceedings of the 4th International Conference on Trends in Welding Research,Gatlinburg,Tennessee,USA,5-8,June,1995
31.R.Kovacevic and Y.M.Zhang.Sensing free surface of arc weld pool using specular reflection:principle and analysis[J].Journal of Manufacturing Science and Engineering,1996,B210.553-564
32.R.Kovacevic and Y.M.Zhang.Real-time image processing for monitoring of free weld pool surface[J].Journal of Manufacturing Science and Engineering,1997,119:161-169
33。高进强.恒流TIG焊接熔池形状参数的视觉检测及智能控制[D].山东大学博士学位论文,2000
34.李鹏九,焊接过程弧光传感的应用基础研究[D].哈尔滨工业大学博士学位论文,1997
35.王克鸿。富氩气保焊熔池信息视觉检测方法试验研究[J].机械工程学报,2004.40(6):161-164
36.闫志鸿.脉沖熔化极气体保护焊接焊接熔池图像的检测与处理[J].焊接学报,2005.26(2):37-40
37.王克争等.MIG焊接熔池的图像处理和数字控制系统[J].清华大学学报,1990.30(2).23-26
38.R.Niepold and F.Bruemmer.Optical sensor system controls arc welding process[J].International Conference on Robots Vision and Sensor Controls,1982
39.Zhenguo Sun.A novel visual image sensor for CO2 short circuiting arc welding and its application in weld reinforcement detection[J].Meas.Sci.Technol,2006(17):1-9
40.曹一鹏.CO_2短路过渡焊接熔池图像传感器[J]。焊接学报,2004.25(2):1-4
41。王庆有.图像传感器应用技术[M].北京:电子工业出版社,2003
42.杨淑莹.VC++图像处理程序设计[M].北京:清华大学出版社,2005
43.孙即祥.图像处理[M]。北京:科学出版社,2004
44.贾云德。机器视觉[M].北京:科学出版社,2000
45.张广军。机器视觉[M].北京:科学出版社,2000
46.CMES。焊接手册[M].北京:机械工业出版社,1995
47。孙俊生.电弧热流与熔滴热焓量分布模式对熔池行为的影响[D].山东工业大学博士学位论文,1998
48.M.C.Tsai.Electromagnetic force induced convection in weld pools with a free surface[J].Welding Journal,1990,69(6):241-234