CN110842392A - Electric arc welding quality defect position prediction method - Google Patents
Electric arc welding quality defect position prediction method Download PDFInfo
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- CN110842392A CN110842392A CN201911175471.5A CN201911175471A CN110842392A CN 110842392 A CN110842392 A CN 110842392A CN 201911175471 A CN201911175471 A CN 201911175471A CN 110842392 A CN110842392 A CN 110842392A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
- B23K31/12—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to investigating the properties, e.g. the weldability, of materials
- B23K31/125—Weld quality monitoring
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/095—Monitoring or automatic control of welding parameters
Abstract
The invention discloses a method for predicting the position of an arc welding quality defect, which comprises the following steps: acquiring current, voltage and welding track of electric arc welding; according to current and voltage of arc welding, by T2Controlling the chart expression to obtain T2A control chart; joining the welding track of the arc welding with T2Controlling time axis synchronization of the graphs; and obtaining T through a control limit expression2Control limits on the control map; according to T2And controlling the time points corresponding to the parts exceeding the control limit on the control chart, and combining the welding machine track to obtain the positions of the arc welding quality defects. The invention converts two welding variables of current and voltage into T2The form of the control chart can greatly avoid the error judgment caused by the joint control of the unary control charts respectively; generating T by welding track and voltage current data2Controlling the time axis of the graph to be synchronized by T2Controlling the time of the abnormal position of the map according to the processing track and the time mapThe position where the quality defect possibly exists is pushed out, and convenience is brought to detection of welding quality.
Description
Technical Field
The invention relates to the technical field of welding quality defect prediction, in particular to an arc welding quality defect position prediction method.
Background
As a traditional processing method, the electric arc welding has obviously improved welding performance along with the continuous development of a welding machine. However, the basic principle of arc welding using arc heat is not changed, and the quality of the arc has a direct relationship with the voltage and current. The prior art, although recording and analyzing current and voltage signals, does not disclose the analysis method. In the field of automation, there is also little concern with automated arc welding control methods for closed loop control methods that use quality as feedback because even if quality problems are detected during operation of automated arc welding, the reason for this cannot be determined due to the complexity of the process environment. Even if some defects are caused by abnormal current and voltage parameters, due to the particularity of the arc welding process and the fact that the overall quality of the welding is not influenced, the welding can only be repaired in a later period through later quality detection.
However, in some automatic arc welding fields, the work task of quality detection is very large due to the overlarge volume of a weldment, and a method capable of predicting the position of a welding defect undoubtedly brings convenience to detection of welding quality.
Disclosure of Invention
The embodiment of the invention provides a method for predicting the position of an arc welding quality defect, which is used for solving the problems in the prior art.
The embodiment of the invention provides a method for predicting the position of an arc welding quality defect, which comprises the following steps:
acquiring current, voltage and welding track of electric arc welding;
according to current and voltage of arc welding, by T2Controlling the chart expression to obtain T2A control chart;
joining the welding track of the arc welding with T2Controlling time axis synchronization of the graphs; and obtaining T through a control limit expression2Control limits on the control map;
according to T2Controlling the time point corresponding to the part exceeding the control limit on the graph, and combining with the welding machine track to obtain the position of the arc welding quality defect;
the T is2The control diagram expression is:
the control limit expression is as follows:
wherein K is a sample; n is the volume per sample;is a sample mean vector;is a sample nominal value vector, S is a covariance matrix of the quality characteristic values, p is the number of the quality characteristic values, m is the number of samples, F is normal distribution, and α is the probability of the first type of error.
Further, said T2Control chart expressionsThe forming specifically includes:
assuming that P quality characteristics obey P-element normal distribution, extracting m samples from the population, wherein the volume of each sample is n, and for a certain sample K, the sample mean values of different quality characteristic values form a sample mean value vector:
and (3) solving the total average value of each quality characteristic to form a sample nominal value vector:
statistic T of corresponding sample K2Comprises the following steps:
wherein [ S ]]p×pIs a covariance matrix of P quality property values:
the mean and variance, covariance for each sample are calculated as follows:
Sjhkrepresenting the covariance of the j-th and h-th quality characteristic values in the k-th sample; the average of the m samples for each statistic was found:
further, said T2The forming of the control chart specifically comprises the following steps:
p quality characteristic values are voltage U and current I and obey binary normal distribution; taking voltage U as X1The current I is taken as X2By substituting the current-voltage data, T is obtained2Control a chart.
Further, the number p of the quality characteristic values is 2.
The embodiment of the invention provides a method for predicting the position of an arc welding quality defect, which has the following beneficial effects compared with the prior art:
the invention converts the current and the voltage of two welding variables into T by carrying out statistical processing on the current and voltage data2The form of the control chart can greatly avoid the error judgment caused by the joint control of the unary control charts respectively. In addition, the invention is applied to the field of automatic welding, and the T generated by welding track and voltage current data2Controlling the time axis of the graph to be synchronized by T2And the time of the abnormal position of the control chart reversely deduces the position where the quality defect possibly exists according to the processing track and the time chart, thereby bringing convenience to welding quality detection.
Drawings
FIG. 1 is a flowchart of a method for predicting a defective location of arc welding according to an embodiment of the present invention;
FIG. 2 shows a diagram of T according to an embodiment of the present invention2Control a chart.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to 2, an embodiment of the present invention provides a method for predicting a position of a quality defect of an arc welding, including:
step 1: and acquiring current, voltage and welding track of the arc welding.
Step 2: according to current and voltage of arc welding, by T2Controlling the chart expression to obtain T2Control a chart.
And step 3: joining the welding track of the arc welding with T2Controlling time axis synchronization of the graphs; and obtaining T through a control limit expression2Control limits on the map.
And 4, step 4: according to T2And controlling the time points corresponding to the parts exceeding the control limit on the control chart, and combining the welding machine track to obtain the positions of the arc welding quality defects.
The specific process of the steps 1-4 is as follows:
the welding quality and welding productivity are greatly affected by the magnitude of the welding current. The welding current mainly affects the size of the penetration. The current is too small, the electric arc is unstable, the fusion depth is small, the defects of incomplete penetration, slag inclusion and the like are easily caused, and the production rate is low; if the current is too large, the weld seam is prone to defects such as undercut and burn-through, and spatter is caused. Therefore, the welding current must be selected appropriately. In the welding process, the load of the welding machine is always changed due to the change of short circuit and arc length, and the output current and voltage of the welding machine are changed according to an external characteristic curve due to the existence of inductive reactance in a welding loop, so that the change range of the current and the voltage is large.
In the embodiment of the invention, assuming that P quality characteristics obey P-element normal distribution, m samples are extracted from the population, the capacity of each sample is n, and for a certain sample K, the sample mean values of different quality characteristic values form a sample mean value vector:
and (3) solving the total average value of each quality characteristic to form a sample nominal value vector:
statistic T of corresponding sample K2Comprises the following steps:
wherein [ S ]]p×pIs a covariance matrix of P quality property values:
the mean and variance, covariance for each sample are calculated as follows:
Sjhkrepresenting the covariance of the j-th and h-th quality characteristic values in the k-th sample; the average of the m samples for each statistic was found:
the P quality characteristic values are voltage U and current I and obey binary normal distribution; taking voltage U as X1The current I is taken as X2By substituting the current-voltage data, T is obtained2Control a chart.
Finally, the control limit expression is:
wherein K is a sample; n is the volume per sample;is a sample mean vector;is a sample nominal value vector, S is a covariance matrix of the quality characteristic values, p is the number of the quality characteristic values, m is the number of samples, F is a normal distribution, α is the probability of a first type of error, the number p of the quality characteristic values takes the value of 2, Fs,m-sAnd (α) checking the numerical value to obtain a table, wherein after the welding operation is finished, α can be selected to obtain a control limit, the part exceeding the control limit is a time point at which a quality defect possibly exists, and the welding track data is searched according to the time point to obtain a welding position for subsequent quality defect inspection and repair of the defect.
It should be noted that, in the embodiment of the present invention, a multivariable control diagram is adopted, and the multivariable control diagram is composed of a voltage I and a current U.
Example (b):
the invention is further explained by combining the attached drawings, and 40mm plates are taken and subjected to a flat welding experiment respectively and combined with a control chart to predict defects. The welding was performed at a voltage of 25V and a current of 180A, and the data shown in Table 1 was substituted into the following equation to obtain a control chart shown in FIG. 2.
TABLE 1
Table 1 shows the data required for the control chart obtained by calculating the current and voltage data collected by performing the flat welding experiment on each 40mm plate and predicting the defect by combining the control chart.
Referring to the flow shown in fig. 1, selecting a reasonable probability α of the first type of error, and further obtaining a control limit, as shown in fig. 2, the part higher than the control limit is a time node where the quality defect may exist, and searching the welding track data according to the corresponding time node to obtain a corresponding position.
The above disclosure is only a few specific embodiments of the present invention, and those skilled in the art can make various modifications and variations of the present invention without departing from the spirit and scope of the present invention, and it is intended that the present invention encompass these modifications and variations as well as others within the scope of the appended claims and their equivalents.
Claims (4)
1. An arc welding quality defect position prediction method is characterized by comprising the following steps:
acquiring current, voltage and welding track of electric arc welding;
according to current and voltage of arc welding, by T2Controlling the chart expression to obtain T2A control chart;
joining the welding track of the arc welding with T2Controlling time axis synchronization of the graphs; and obtaining T through a control limit expression2Control limits on the control map;
according to T2Controlling the time point corresponding to the part exceeding the control limit on the graph, and combining with the welding machine track to obtain the position of the arc welding quality defect;
the T is2The control diagram expression is:
the control limit expression is as follows:
wherein K is a sample; n is the volume per sample;is a sample mean vector;is a sample nominal value vector, S is a covariance matrix of the quality characteristic values, p is the number of the quality characteristic values, m is the number of samples, F is normal distribution, and α is the probability of the first type of error.
2. The arc welding quality defect location prediction method of claim 1, wherein T is2Controlling the formation of the expression, specifically comprising:
assuming that P quality characteristics obey P-element normal distribution, extracting m samples from the population, wherein the volume of each sample is n, and for a certain sample K, the sample mean values of different quality characteristic values form a sample mean value vector:
and (3) solving the total average value of each quality characteristic to form a sample nominal value vector:
statistic T of corresponding sample K2Comprises the following steps:
wherein [ S ]]p×pIs a covariance matrix of P quality property values:
the mean and variance, covariance for each sample are calculated as follows:
Sjhkrepresenting the covariance of the j-th and h-th quality characteristic values in the k-th sample; the average of the m samples for each statistic was found:
3. the arc welding quality defect location prediction method of claim 2, wherein T is2The forming of the control chart specifically comprises the following steps:
p quality characteristic values are voltage U and current I and obey binary normal distribution; taking voltage U as X1The current I is taken as X2By substituting the current-voltage data, T is obtained2Control a chart.
4. The arc welding quality defect position prediction method according to claim 1, wherein the number p of the quality characteristic values takes a value of 2.
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Citations (5)
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CN1266391A (en) * | 1997-08-08 | 2000-09-13 | 株式会社安川电机 | Arc welding monitoring device |
US6583386B1 (en) * | 2000-12-14 | 2003-06-24 | Impact Engineering, Inc. | Method and system for weld monitoring and tracking |
EP2474380A1 (en) * | 2009-07-02 | 2012-07-11 | Soudronic AG | Method and welding device for analysing the welding electric current for container clamp welding |
CN104379291A (en) * | 2012-04-23 | 2015-02-25 | 林肯环球股份有限公司 | System and method for monitoring weld quality |
CN107004375A (en) * | 2014-06-27 | 2017-08-01 | 伊利诺斯工具制品有限公司 | The system and method for monitoring weld information |
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Patent Citations (5)
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CN1266391A (en) * | 1997-08-08 | 2000-09-13 | 株式会社安川电机 | Arc welding monitoring device |
US6583386B1 (en) * | 2000-12-14 | 2003-06-24 | Impact Engineering, Inc. | Method and system for weld monitoring and tracking |
EP2474380A1 (en) * | 2009-07-02 | 2012-07-11 | Soudronic AG | Method and welding device for analysing the welding electric current for container clamp welding |
CN104379291A (en) * | 2012-04-23 | 2015-02-25 | 林肯环球股份有限公司 | System and method for monitoring weld quality |
CN107004375A (en) * | 2014-06-27 | 2017-08-01 | 伊利诺斯工具制品有限公司 | The system and method for monitoring weld information |
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徐鹏航: "《质量管理指南》", 28 February 1995, 中国时政经济出版社 * |
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Application publication date: 20200228 |