JP2010201474A - Method and system for optimization of welding, and welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately analyze the values of residual deformation and residual stress after welding at the stage of weld designing, and determine optimal welding conditions according to the analyzed result. <P>SOLUTION: Welding conditions of a welding pass in an arbitrary order are determined in a proper range, where welding defects are not generated, taking into consideration the welding deformation of the analyzed shape of a joint caused in the previous welding pass (S15). A cross-sectional shape of the weld bead in the welding pass in the order is calculated based on the welding conditions (S16). The cross-sectional shape of the weld bead is modeled and added to basic analysis models (S17). Welding deformation of the groove shape of the joint in the welding pass in the order is calculated with a thermal elastoplasticity analysis, using the analyzed model (S18). Welding passes in other orders are also subjected to the same steps as the above to complete the welding analysis of the weld joint, and the number of welding passes is determined (S19). When the decision index value of the weld joint is within an allowable range, the kind of the joint, the groove shape of the joint, the number of the welding passes, and the welding conditions of each pass are recorded and stored (S23). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a welding optimization method and an optimum welding method for optimally performing a welding design for performing multiple layers of welding by performing a plurality of welding passes on a joint groove formed in a welded joint portion of a welded structure. The present invention relates to a welding system and a welding method using this welding optimization method.

  Generally, in a welded structure, residual deformation and residual stress may be generated by welding, and if such residual deformation and residual stress exceed a predetermined value, the quality of the welded structure may be adversely affected. Therefore, it is necessary to reduce residual deformation and residual stress as much as possible.

  Conventionally, as means for reducing residual deformation or residual stress in the welding process, it is performed depending on the experience and intuition of the field worker, or the field worker's know-how is input to the automatic welding apparatus as numerical data, or Analysis and evaluation methods by simulation are being implemented.

  For example, the shape of the joint groove is detected, and when offline, the welding conditions such as the welding current and welding speed are considered in consideration of the relationship with the optimal welding path cross-sectional area according to the detected joint groove shape. Japanese Patent Application Laid-Open No. H10-228707 discloses a method for performing welding by controlling an automatic welding apparatus according to the adjusted welding conditions.

  Also, when setting the welding conditions according to the shape of the joint groove of the welded structure, the order of lamination of the welding paths under the specific welding conditions shall be determined, and the residual stress analysis by welding under the specific welding conditions To select the welding pass stacking order that minimizes the residual stress value at the point of interest set in advance as the residual stress evaluation point by sequentially comparing the stacking order of multiple welding passes and welding in the selected order. Is disclosed in Patent Document 2.

  Furthermore, when performing multi-layer welding, an analytical model corresponding to preset welding conditions is generated, the temperature of the member is measured in the process of welding to obtain a measured temperature, and after welding is completed for each welding pass, Perform thermal elasto-plastic analysis on the analysis model, evaluate the residual stress according to the measured temperature, obtain the estimated residual stress, and perform welding by changing the welding conditions of the remaining welding path according to this estimated residual stress This is disclosed in Patent Document 3.

Japanese Patent Laid-Open No. 9-9936 JP-A-9-1376 JP 2004-181462 A JP 2005-83810 A

Noda Hirohisa et al., Prediction of Hot Cracking during T-joint Full Penetration Welding Using Temperature-Dependent Interface Element Method, Outline of Lecture at the National Welding Society (2007 Spring National Convention), Japan Welding Society, No. 80, March 2007 Satoshi Yamane et al., Numerical Simulation of Weld Pool in Narrow Gap Welding, Outline of National Welding Society Conference (FY2006 National Convention), Japan Welding Society, No. 79, September 2006

  In general, when performing multi-layer welding of welded structures, the welding pass plan for the entire welded joint, and welding conditions such as the welding voltage, welding current, and welding speed of each welding pass can be planned or estimated in advance from the experience of field workers. However, since the joint groove shape is deformed by welding in practice, the welding path plan deviates particularly as the final layer is approached. In the automatic welding apparatus described in Patent Document 1, the welding deformation of the joint groove shape is detected at any time, and welding is performed by changing the welding conditions as appropriate. Therefore, there is a problem that the number of welding passes after the end of welding cannot be determined unless the welding operation is actually performed.

  Also, when evaluating residual stress by analysis, this residual stress is evaluated by using an estimated evaluation based on a welding path plan that does not consider welding deformation (Patent Document 2) or a temperature measured during actual welding. It becomes the post-mortem analysis evaluation (Patent Document 3). Therefore, in these Patent Documents 2 and 3, the number of welding passes cannot be accurately grasped at the stage of welding pass planning, and the residual deformation and residual stress of the welded structure can be evaluated with high accuracy by analysis at the stage of welding design. It is not.

  The object of the present invention has been made in consideration of the above-mentioned circumstances, and it is possible to analyze the value of residual deformation and residual stress, which are judgment index values after welding at the stage of welding design, with high accuracy. Accordingly, it is an object of the present invention to provide a welding optimization method and system and a welding method capable of determining optimum welding conditions accordingly.

  The welding optimization method according to the present invention is a welding that optimizes a welding design for performing a plurality of welding passes by performing a plurality of welding passes on a joint groove formed in a welded joint portion of a welded structure. A method for optimizing a basic analysis model generating step for generating a basic analysis model in accordance with the type of joint of the weld joint and the shape of the joint groove for the welded structure, and a welding path in an arbitrary order The welding conditions are determined within an appropriate range that does not cause welding failure in consideration of the welding deformation of the joint groove shape caused by the welding path made before the welding conditions. A welding condition determination step for obtaining a weld bead cross-sectional shape of a weld pass, an analysis model of the weld bead cross-sectional shape of the arbitrary order of the weld passes, and adding the analysis model to the basic analysis model. Using a model, a welding deformation analysis step for obtaining a welding deformation of the joint groove shape caused by this arbitrary order of welding passes by a thermoelastic-plastic analysis, a determination step of the welding conditions, etc., and a welding deformation analysis step, etc. After completing the weld analysis of the weld joint and determining the number of weld passes, a determination index value is obtained for the weld joint, and whether the determination index value is within an allowable range. If it is not within the allowable range, the welding condition including the type of joint and the shape of the joint groove is changed to determine the basic analysis model generation step, the welding condition determination step, and the welding. When the index determination step for executing the deformation analysis step again and the determination index value in the index determination step are within an allowable range, the type of joint and the joint Shape of the groove, the welding pass number, is characterized in that it has a, a data recording step of storing records in the analysis result database welding conditions for each welding pass.

  In addition, the welding optimization system according to the present invention optimizes a welding design for performing multiple layers of welding by performing a plurality of welding passes on a joint groove formed in a welded joint portion of a welded structure. A welding optimization system for performing a basic analysis model generation step for generating a basic analysis model for generating a basic analysis model according to the type of joint of the weld joint and the shape of the joint groove for the welded structure The welding conditions of the generating means and the welding pass in an arbitrary order are determined within an appropriate range that does not cause welding failure in consideration of the welding deformation of the joint groove shape by the welding pass made before that, and this welding Welding condition etc. determining means for executing a welding condition etc. determining step for obtaining the weld bead cross-sectional shape of the welding pass in this order based on the conditions, and the weld bead cross-sectional shape of the arbitrary order welding pass. An analysis model is added to the basic analysis model, and the weld deformation of the joint groove shape caused by the welding pass in this arbitrary order is obtained by thermoelastic-plastic analysis using the analysis model obtained by the addition. Welding deformation analysis means for executing a welding deformation analysis step, the welding condition determination step and the welding deformation analysis step are performed with respect to another order of welding paths, and the welding analysis of the welded joint portion is completed, and the number of welding paths After the determination, a determination index value is obtained for the welded joint, and it is determined whether or not the determination index value is within the allowable range. If the determination index value is not within the allowable range, the type of the joint and the joint opening are determined. An index determination step in which the welding condition including the previous shape is changed and the basic analysis model generation step, the welding condition determination step, and the welding deformation analysis step are executed again. When the index determination means for executing the index and the determination index value in the index determination step are within an allowable range, the analysis results of the joint type, the shape of the joint groove, the number of welding passes, and the welding conditions of each welding pass And a data recording means for executing a data recording step of recording and storing the data in a database.

  Furthermore, the welding method according to the present invention performs actual welding according to the type of joint, the shape of the joint groove, the number of welding passes, and the welding conditions of each welding pass determined by the welding optimization method according to the present invention. It is characterized by that.

  According to the welding optimization method, the welding optimization system and the welding method according to the present invention, the welding analysis of the welded joint portion is performed in consideration of the welding deformation of the joint groove shape, so It is possible to create an accurate welding pass plan including the number of welding passes according to the welding construction. For this reason, the number of welding passes substantially coincides with the number of welding passes in actual welding work, and the amount of heat input can be made substantially the same as the actual heat input amount. These residual deformation values and residual stress values can be analyzed and evaluated accurately with respect to the residual stress values. Accordingly, it is possible to determine an optimum welding condition that can suppress determination index values such as a residual deformation value and a residual stress value within an allowable range.

Explanatory drawing which shows the welding method by the automatic welding machine provided with the welding optimization system which implements 1st Embodiment of the welding optimization method which concerns on this invention. The block diagram which shows the structure of the welding optimization system of FIG. The flowchart which shows the welding optimization method which the welding optimization system of FIG. 2 implements. (A) is a perspective view which shows the welding structure of FIG. 1, (B) is a perspective view which shows the welded joint part before welding which expanded the IV section of FIG. 4 (A). The analysis model figure which shows the basic analysis model which modeled the welding structure of FIG. The graph which shows the relationship between welding current, welding speed, and welding beat cross-sectional area. The analysis model figure which shows the analysis model which modeled and added the welding beat cross-sectional shape of the 1st welding pass to the basic analysis model of FIG. The analysis model figure which shows the other example of the analysis model which modeled and added the welding beat cross-sectional shape of the 1st welding pass to the basic analysis model of FIG. A weld bead sectional view explaining a welding pass plan which does not consider welding deformation in a weld joint part. A weld bead sectional view explaining a welding pass plan which considered welding deformation in a weld joint part. The front view which shows when the groove angle is varied in the weld joint shown in FIG. The flowchart which shows 2nd Embodiment of the welding optimization method which concerns on this invention. The flowchart which shows 3rd Embodiment of the welding optimization method which concerns on this invention. The graph which shows the relationship between heat input / welding speed and the aspect ratio of a welding beat. Explanatory drawing which shows the weld joint part for demonstrating 4th Embodiment of the welding optimization method which concerns on this invention.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[A] First embodiment (FIGS. 1 to 11)
FIG. 1 is an explanatory view showing a welding method by an automatic welder equipped with a welding optimization system for carrying out the first embodiment of the welding optimization method according to the present invention. FIG. 2 is a block diagram showing a configuration of the welding optimization system of FIG. FIG. 3 is a flowchart showing a welding optimization method performed by the welding optimization system of FIG.

  An automatic welding machine 10 as an automatic welding apparatus shown in FIG. 1 has a plurality of joint grooves 3 (FIG. 4 (B)) formed on welded joint portions 2 of thick plates 1A and 1B as welded structures. A plurality of layers of welding (so-called multi-layer welding) are actually performed by performing a welding pass. The automatic welder 10 includes a welding torch 11, an automatic welder control device 12, an automatic welder power supply device 13, and a welding condition database 14 as an analysis result database.

  Power is supplied to the welding torch 11 from the automatic welder power supply device 13. The automatic welder control device 12 controls the welding torch 11 for each welding pass based on the welding conditions stored in the welding condition database 14, and performs welding, for example, arc welding, to the welded joint portions 2 of the thick plates 1A and 1B. Enforce. The welding condition database 14 records the welding conditions, which are analysis results analyzed by the welding optimization system 15, that is, the type of joint, the shape of the joint groove, the number of welding passes, and the welding conditions of each welding pass. Saved (see FIG. 3). The welding conditions of each welding pass include a welding method, a welding posture, a welding voltage, a welding current, a welding speed, a weld metal supply amount, a welding rod (weld metal) diameter, a welding pass shape, a welding pass position, and the like.

  The welding optimization system 15 executes a welding optimization method for optimally designing a weld for performing a plurality of layers of welding. The welding conditions, which are the results of analysis by the welding optimization system 15, are input to the automatic welding machine control device 12 via the welding condition database 14, and as input data for actual welding execution using the automatic welding machine 10. Used.

  When actual welding using the automatic welder 10 is performed, a displacement sensor (for example, a laser displacement meter) 16, a temperature sensor (for example, a thermocouple) 17, and a welding record database 18 are used. The displacement sensor 16 measures the position of each welding pass and the welding deformation of the joint groove 3 shape. Moreover, the temperature sensor 17 is installed in the welding joint part 2 vicinity, and measures the temperature history at the time of the welding construction of each welding pass.

  As shown in FIG. 3, the welding record database 18 includes a temperature sensor 17 together with welding conditions such as a joint type, a joint groove shape, the number of welding passes, and welding conditions of each welding pass during actual welding. The temperature history information measured in step 1 and the welding deformation information of the joint groove 3 shape measured by the displacement sensor 16 are recorded and stored as welding execution information in association with the welding conditions.

  Here, the name handled by the multilayer pile welding of this embodiment is demonstrated. “Bead” refers to a solidified mass after the weld metal that is stacked on the joint in a single weld is melted. “Layer” refers to a layer of beads that is stacked on the joint. This refers to the welding of multiple layers of beads. The “pass” refers to a single welding operation performed along the welding direction.

  As shown in FIG. 2, the welding optimization system 15 that executes the welding optimization method includes basic analysis model generation means 19 that executes a basic analysis model generation step, welding conditions that execute a welding condition determination step, and the like. The determining unit 20 includes a welding deformation analyzing unit 21 that executes a welding deformation analyzing step, an index determining unit 22 that executes an index determining step, and a data recording unit 23 that executes a data recording step.

  The basic analysis model generation step executed by the basic analysis model generation means 19 is a basic analysis model corresponding to the type of joint of the welded joint portion 2 and the shape of the joint groove 3 for, for example, the thick plates 1A and 1B as the welded structures. 24 (FIG. 5; detailed later) is generated. This basic analysis model generation step corresponds to steps S11 to S13 in FIG.

  The welding condition etc. determining step executed by the welding condition etc. determining means 20 is performed by first setting the welding conditions of the welding pass in an arbitrary order (for example, k-th (k is an integer of 1 or more)) before the welding pass. In consideration of the welding deformation of the joint groove 3 shape due to the above, it is determined within an appropriate range that does not cause welding failure. In this embodiment, the welding conditions are determined by selecting, for example, a welding voltage, a welding current, a welding speed, a welding metal supply amount, a welding rod diameter, and the like from the welding record database 18 in which actual welding execution information is stored in advance. Is done. Next, a welding condition etc. determination step calculates | requires the welding beat cross-sectional shape of this kth welding pass based on this determined welding condition. This step for determining welding conditions and the like corresponds to steps S15 and S16 in FIG.

  In the welding deformation analysis step executed by the welding deformation analysis means 21, first, the weld beat cross-sectional shape of the k-th welding path is converted into an analysis model, and this bead analysis model 25 is added to the basic analysis model 24 to add an analysis model 26 (both together). FIG. 7; details will be generated later. Next, in the welding deformation analysis step, the weld deformation of the joint groove shape generated by the k-th welding pass is obtained by thermoelastic-plastic analysis using the analysis model 26. This welding deformation analysis step corresponds to steps S17 and S18 in FIG.

  The above-described welding condition determination step and welding deformation analysis step are also executed for the other welding passes, that is, the welding passes after the k-th welding pass, and the welding analysis of the welded joint portion 2 is completed and the welding pass is completed. The number n (n is an integer of 2 or more) is determined.

  In the index determination step executed by the index determination means 22, first, after determining the number of welding passes n in the welded joint portion 2, a determination index value when all the weld passes are executed in the welded joint portion 2 is obtained. This determination index value is a residual deformation value of the welded joint portion 2 after completion of the welding analysis, and is obtained by thermoelastic-plastic analysis. In the index determination step, it is next determined whether or not the obtained residual deformation value is within an allowable range, for example, whether or not it is equal to or less than a preset allowable residual deformation value.

  In the index determination step, if the obtained residual deformation value exceeds the allowable residual deformation value, the joint type, joint groove shape, and welding conditions of each welding pass are changed, and the basic analysis model generation step, welding The condition determination step and the welding deformation analysis step are executed again. This index determination step corresponds to steps S21 and S22 in FIG.

  The data recording step executed by the data recording means 23 includes the joint type, joint groove shape, number of welding passes, and welding conditions for each welding pass when the residual deformation value in the index determination step is equal to or less than the allowable residual deformation value. Is recorded and stored in the welding condition database 14. This data recording step corresponds to step S23 in FIG.

  Next, a welding optimization method including the above-described basic analysis model generation step, welding condition determination step, welding deformation analysis step, index determination step, and data recording step will be described with reference to FIGS. Explained.

  As shown in FIG. 3, in order to optimize the welding process of the welded structure, first, the shape and material of the target welded structure are determined (S11). Next, the type of joint and the shape of the joint groove 3 are selected (S12), and a basic analysis model 24 for performing analysis evaluation is generated (S13).

  In the present embodiment, for example, consider a case in which two thick plates 1A and 1B having a joint groove 3 having a V-shaped groove shape are multilayered by arc welding in a butt joint as shown in FIG. Here, assuming that the groove angle of the joint groove 3 is θ1, the basic analysis model 24 excluding the weld pass portion is generated. That is, with respect to the base material, as shown in FIG. 5, an element using a finite element method is created and a basic analysis model 24 is generated. For the sake of explanation, a simple two-dimensional model is used. However, in order to accurately obtain the welding deformation of the joint groove 3 shape, it is preferable to use the three-dimensional model rather than the two-dimensional model.

  Next, the parameter k for counting the welding passes is set to 1 (S14). Then, referring to the welding record database 18 in which various welding conditions are stored in advance, the optimum conditions (welding voltage, welding current, welding speed, weld metal supply) as the welding conditions of the kth (first) welding pass are referred to. Amount, welding rod diameter, etc.) are determined (S15). Among these welding conditions, the welding current, the welding voltage, and the welding speed that are particularly closely related to the welding failure are selected within an appropriate range that does not cause welding defects such as hot cracking, fusion failure, undercut, and overlap.

  When selecting the welding conditions in the k-th welding pass, the welding deformation of the three weld groove shapes in the (k-1) -th welding pass made before that is considered. Here, the welding deformation of the weld groove 3 shape in the (k-1) th welding pass was analyzed by the thermoelastic-plastic analysis (S18 in FIG. 3) in the welding deformation analysis step in the welding deformation analysis means 21. Is used.

  Next, a weld bead cross-sectional shape is obtained from the welding conditions selected in step S15 (S16). The weld bead cross-sectional shape can be estimated from the weld metal supply amount, the welding rod diameter, and the welding speed in the weld record database 18. For example, if the length of the weld joint 2 is L = 240 mm, the welding speed Vw = 60 mm / min, the weld metal supply amount Vp = 120 mm / min, and the welding rod diameter D = 2 mm, the weld bead cross-sectional area S is It is obtained from the following formula.

[Equation 1]
S = (D / 2) ² × π × (Vp × L / Vw) / L = (D / 2) ² × π × Vp / Vw
= (2/2) ² × π × 120/60 = 6.23 mm ²

  With respect to the weld bead cross-sectional area S, the weld bead cross-sectional shape (weld path shape) is obtained from the dimensions of the joint groove 3 to be filled with the weld bead, and one layer is constituted by one weld pass, or one layer It is determined at this stage whether or not to consist of a plurality of welding passes.

  Further, as a method for obtaining the weld bead cross-sectional area S, the relationship among the welding current, the welding speed, and the weld bead cross-sectional area is extracted from the welding record database 18 and graphed as shown in FIG. It may be obtained from this graph. That is, as can be seen from the graph shown in FIG. 6, the weld bead cross-sectional area has a substantially linear proportional relationship with the welding current, and has an inverse proportional relationship with the welding speed. Such a graph can be selected if the representative points (for example, points A and B in FIG. 6) that can be linearly approximated for each welding method and welding posture are grasped by an element test in advance and added to the welding record database 18. The weld bead cross-sectional area can be obtained from the welding current and the welding speed. Furthermore, for any welding condition that does not exist in the welding record database 18, the weld bead cross-sectional area can be obtained by linearly interpolating from the welding current and the welding speed.

  The bead analysis model 25 obtained by analyzing the weld bead cross-sectional shape of the k-th welding pass is added to the basic analysis model 24 as shown in FIG. 7 to generate an analysis model 26 (S17). At this time, if the k-th bead analysis model 25A and the node of the basic analysis model 24 do not match, the node of the basic analysis model 24 becomes the node of the k-th bead analysis model 25A as shown in FIG. The analysis model 26A is generated by making modifications so as to match.

  Next, using the analysis models 26 and 26A, the welding deformation of the joint groove 3 shape is analyzed and predicted from the thermoelastic-plastic analysis by the k-th welding pass (S18). When performing thermoelastic-plastic analysis as a general known technique, it is necessary to perform heat conduction analysis in order to obtain temperature distribution data of the welded joint portion 2 and its vicinity. In the present embodiment, a case where temperature history data corresponding to the welding condition of the kth welding pass exists in the welding record database 18 will be described.

  In the analysis models 26 and 26A, the heat conduction analysis is performed based on the welding conditions of the kth welding pass, and the temperature distribution and temperature history of the entire analysis models 26 and 26A are obtained to obtain the analysis temperature Ta. The temperature history data in the welding record database 18 is represented by the measured temperature Te, and the positions on the analysis models 26 and 26A corresponding to the positional relationship between the actual heat source (welding torch 11) at which the measured temperature Te is measured and the temperature sensor 17. (For example, the temperature sensor corresponding point C in FIG. 7), Ta represents the analysis temperature obtained by the heat conduction analysis as described above.

  The analysis temperature Ta is desirably Ta = Te. However, according to the experience of the present inventors, if the value of the ratio of each peak temperature (Te−Ta) / Te is within ± 5%, the thermoelastic-plasticity It is confirmed that the analysis value obtained by the analysis is an appropriate value. In the following description, it is assumed that Ta = Te. However, the temperature comparison operation between the analysis temperature Ta and the measurement temperature Te is referred to as temperature calibration.

  As a result of temperature calibration, if Ta ≠ Te (that is, if the value of (Te−Ta) / Te exceeds ± 5%), the heat input conditions of the analysis models 26 and 26A, that is, the welding voltage Ek and the welding The product of the current Ik (heat input amount Q) is corrected, for example, by changing the heat input efficiency, and the heat conduction analysis is repeated until Ta = Te. At the stage when Ta = Te, the thermoelastic-plastic analysis is performed using the analysis temperature Ta obtained by the temperature calibration, and the weld deformation of the joint groove 3 shape is obtained.

  Next, it is determined whether or not all of the welded joint portions 2 have been subjected to the weld analysis as described above on the analysis models 26 and 26A (S19), and the weld analysis is not performed on all of the welded joint portions 2 1 is added to the parameter k (S20), the welding conditions are selected (S15), the weld bead cross-sectional shape is determined (S16), and the thermoelastic-plastic analysis (S17, S18) is performed for the first to nth welding passes. ) In sequence. At the stage where the welding analysis is executed in all of the welded joint portions 2, the welding deformation of the joint groove 3 shape in the welded joint portion 2 is accumulated to obtain a residual deformation (S21). Note that the parameter k is n when welding is completed, and therefore the total number of welding passes of the weld joint 2 is n.

  Here, when selecting the welding conditions in step S15, the analysis is performed in consideration of the welding deformation of the joint groove 3 shape generated during welding, and the welding deformation of the joint groove shape as in Patent Document 2 is performed. Compare the differences in the number of welding passes when the analysis is performed without consideration. FIG. 9 is a cross-sectional view of a weld bead planned without considering the weld deformation of the joint groove shape, and FIG. 10 is a weld bead planned in consideration of the weld deformation of the joint groove 3 shape generated during welding in step S15. It is sectional drawing. In FIG. 10, the broken line is the joint groove shape when welding deformation is not considered, and the solid line is the final shape of the joint groove 3 considering welding deformation. Moreover, the ◯ numerals in FIGS. 9 and 10 represent welding pass numbers.

  As shown in FIG. 10, the groove angle of the joint groove 3 gradually decreases as the welding analysis for sequentially constructing the welding paths is performed. Thereby, for example, when the number of welding passes of the fourth layer is compared, the number of welding passes decreases from 3 passes to 2 passes, and from the 4th pass to 3 passes in the sixth layer of the final layer.

  Thereafter, the residual deformation value Σε in all the welding passes is obtained from the thermoelastic-plastic analysis result after completion of the welding analysis of the welded joint portion 2 (S21). Next, the residual deformation value Σε obtained by this analysis is compared with a predetermined allowable residual deformation value (S22). If the residual deformation value Σε> the allowable residual deformation value, the process returns to step S12, and, for example, as shown in FIG. 11, the groove angle θ1 of the joint groove 3 is reduced and changed to the groove angle θ2 (θ2 <θ1). Alternatively, the welding conditions are changed in step S15, and thereafter, new analysis models 26 and 26A are generated (S17), the welding deformation is analyzed (S18), and these are executed for all the welding passes (S19). , S20) The residual deformation value is evaluated (S21). Here, the reason why the groove angle of the joint groove 3 is reduced is that residual deformation and residual stress can be suppressed by reducing the number of welding passes to reduce the heat input.

  On the other hand, if the residual deformation value Σε ≦ allowable residual deformation value, all welding conditions (joint type, joint groove shape, welding conditions for each welding pass, number of welding passes, etc.) and analysis results (for each welding pass) The weld bead cross-sectional shape, the residual deformation value of all the weld passes in the weld joint 2 and the like are recorded and stored in the welding condition database 14 (S23), and the analysis routine is terminated. As described above, the welding conditions stored in the welding condition database 14 are used, for example, as input data of the automatic welding machine 10 shown in FIG.

  Therefore, according to the present embodiment, the following effect (1) is obtained.

  (1) In the welding optimization method executed by the welding optimization system 15, the welding deformation of the joint groove 3 shape is considered in the welding condition determination step (S15, S16) and the welding deformation analysis step (S17, S18). By executing the welding analysis of the welded joint portion 2, it is possible to create an accurate welding pass plan including the number of welding passes in accordance with the actual welding execution before the welding is executed. For this reason, the number of welding passes is approximately the same as the number of welding passes for actual welding execution, and the amount of heat input can be made substantially the same as the actual amount of heat input. Thus, in the index determination step (S21, S22), the residual deformation value can be analyzed and evaluated with high accuracy. Therefore, it is possible to determine an optimum welding condition that can suppress the residual deformation value within an allowable range.

[B] Second embodiment (FIG. 12)
FIG. 12 is a flowchart showing a second embodiment of the welding optimization method according to the present invention. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The welding optimization method executed by the welding optimization system of the present embodiment is different from that of the first embodiment in that the determination index value used in the index determination step (S41, S42) is after the welding analysis is completed. This is a point that is a residual stress value of the welded joint portion 2. The residual stress value is obtained from the residual deformation value of the welded joint portion 2 after completion of the welding analysis obtained from the thermoelastic-plastic analysis or directly obtained from the thermoelastic-plastic analysis.

  That is, steps S31 to S39 and S43 are the same as steps S11 to S19 and S23 of the first embodiment, respectively. In step S41, a residual stress value σR in all welding passes is obtained from the thermoelastic-plastic analysis result (residual deformation value of the welded joint portion 2) after completion of the welding analysis in steps S38 and S39 (S41). Next, the obtained residual stress value σR is compared with a predetermined allowable residual stress value (S42). If “residual stress value σR> allowable residual stress value”, the process returns to step S32, and the groove angle θ1 of the joint groove 3 is reduced to a groove angle θ2 as shown in FIG. 11, or in step S35. The welding conditions are changed, and then new analysis models 26 and 26A are generated (S37), the welding deformation is analyzed (S38), and these are executed for all the welding passes (S39, S40). Is evaluated (S41).

  On the other hand, if “residual stress value σR ≦ allowable residual stress value”, all welding conditions (joint type, joint groove shape, welding conditions of each welding pass, number of welding passes, etc.) and analysis results (each welding) The weld bead cross-sectional shape of the pass, the residual stress value of all the weld passes in the welded joint portion 2 and the like) are recorded and stored in the welding condition database 14 (S43), and the analysis routine is terminated.

  Therefore, according to the present embodiment, the following effect (2) is obtained.

  (2) In the welding optimization method executed by the welding optimization system, the welding deformation of the joint groove 3 shape is taken into consideration in the welding condition determination step (S35, S36) and the welding deformation analysis step (S37, S38). By executing the welding analysis of the welded joint portion 2, an accurate welding path plan including the number of welding paths in accordance with the actual welding can be created before the welding is performed. For this reason, the number of welding passes is approximately the same as the number of welding passes for actual welding execution, and the heat input can be made substantially the same as the actual heat input amount. On the other hand, in the index determination step (S41, S42), the residual stress value can be analyzed and evaluated with high accuracy. Therefore, it is possible to determine an optimum welding condition that can suppress the residual stress value within an allowable range.

[C] Third embodiment (FIGS. 13 and 14)
FIG. 13 is a flowchart showing a third embodiment of the welding optimization method according to the present invention. In the third embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The welding optimization method executed by the welding optimization system of the present embodiment is different from that of the first embodiment in that the welding conditions that are suitable for the determination of the kth welding condition performed by the welding condition etc. determining step. Is determined in the welding record database 18 (S55 in FIG. 13), and when no suitable welding condition exists in the welding record database 18, the welding condition is determined by analysis (FIG. 13 S58) is added.

  In other words, steps S51 to S54 are the same as steps S11 to S14 of the first embodiment, steps S56 and S57 are the same as steps S15 and S16 of the first embodiment, respectively, and step S59. To S65 are the same as steps S17 to S23 of the first embodiment, respectively.

  In step S55, when selecting the welding condition in the k-th welding pass, it is first determined whether or not there is a suitable welding condition in the welding record database 18. If it is determined that the welding condition of the k-th welding pass exists, the process proceeds to steps S56 and S57 that are the same as those in the first embodiment.

  If it is determined in step S55 that the welding condition of the k-th welding pass does not exist, the process proceeds to step S58 in which the welding condition is determined by analysis. In this welding condition analysis step S58, the amount of heat input (in the case of arc welding, welding voltage and welding current), welding speed, welding metal supply amount, welding rod diameter and other welding conditions, and the weld bead cross-sectional shape are determined by analysis.

  As an analysis example regarding a welding defect, for example, Non-Patent Document 1 and the like are known. That is, the welding condition in the kth welding pass is determined from the weld defect analysis using the dynamic model. Specifically, using the relationship between the welding heat analysis (heat input / welding speed) and the welding bead aspect ratio (Fig. 14), the evaluation points are within the range where normal welding without welding defects can be performed. D is determined, and at this evaluation point D, the welding speed, heat input (welding current and welding voltage), the cross-sectional shape of the welding beat, and the like are determined.

  Further, as an analysis example for determining the weld bead cross-sectional shape, for example, Non-Patent Document 2 is known. That is, the welding beat cross-sectional shape of the k-th welding path is determined from the heat transfer analysis using the heat conduction equation using the welding current, the welding voltage, and the welding speed. Specifically, if the welding speed and the amount of heat input (welding current, welding speed) are determined, for example, from the above-described welding defect analysis, the heat conduction equation (Goldac's two-elliptic heat model equation, From the heat transfer analysis using the thermal diffusion model equation), the welding beat cross-sectional shape is determined.

  Further, when temperature data corresponding to an arbitrary welding condition does not exist in the welding record database 18, for example, the heat transfer analysis method disclosed in the above-mentioned Patent Document 4 or the like, that is, the heat conduction equation (Goldac's two ellipses) It is possible to obtain temperature history data by heat transfer analysis using an exothermic model equation and a thermal diffusion model equation). That is, the temperature change caused by the welding torch in the welded structure is obtained by numerically solving the heat conduction equation described by the differential equation or integral equation by discretizing the space and time, and the temperature history during welding Ask for data. This temperature history data is regarded as the measured temperature Te and compared with the analysis temperature Ta.

  After determining the weld bead cross-sectional shape of the k-th weld pass in step S57, or in step S58, the welding conditions of the k-th weld pass are determined by analysis, and the weld bead cross-sectional shape of the k-th weld pass is determined. After the determination, the welding deformation of the joint groove 3 shape is analyzed by thermal elastic-plastic analysis in steps S59 to S62, and thereafter steps S63 to S65 are executed. In steps S63 and S64, a residual stress value similar to that of the second embodiment may be used instead of the residual deformation value.

  Therefore, according to the present embodiment, the following effect (3) is achieved.

  (3) In the welding optimization method executed by the welding optimization system, the welding deformation of the joint groove 3 shape is taken into consideration in the welding condition determination step (S55 to S58) and the welding deformation analysis step (S59, S60). By executing the welding analysis of the welded joint portion 2, an accurate welding path plan including the number of welding paths in accordance with the actual welding can be created before the welding is performed. For this reason, the number of welding passes substantially coincides with the number of welding passes for actual welding execution, and the heat input can be made substantially the same as the actual heat input amount. In the index determination step (S63, S64), the residual deformation value and the residual stress value can be analyzed and evaluated with high accuracy for the stress value. Therefore, it is possible to determine an optimum welding condition that can suppress the residual deformation value and the residual stress value within an allowable range.

[D] Fourth embodiment (FIG. 15)
FIG. 15 is an explanatory view showing a welded joint portion for explaining a fourth embodiment of the welding optimization method according to the present invention. In the fourth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The welding optimization method executed by the welding optimization system of the present embodiment is different from that of the first embodiment in that, in the welding condition determination step, welding conditions in an arbitrary order (k-th) are welded. This is a point determined so that the cross-sectional area of the welding pass in this order is maximized within an appropriate range in which no defect occurs.

  In general, when welding is performed, the welding current is set lower in the first layer and the second layer. This is to prevent the bottom of the welding groove 3 from being melted by heat input by welding and the bottom of the welding groove 3 from being melted down. Further, in the final layer, the welding current is similarly set to be low in order to keep the finished surface of the welding clean. Therefore, the selection of the welding condition that maximizes the weld bead cross-sectional shape shown in the present embodiment is performed for the layers from the third layer onward to the last layer.

  FIG. 15 shows an example in which the welding conditions and the weld bead cross-sectional shape of the fifth welding pass are determined. The weld bead cross-sectional shape when the welding current Ik and the welding speed Vk are set to average welding conditions within an appropriate range that does not cause poor welding now is represented by a region of ○ alphanumeric characters in FIG. On the other hand, the welding bead cross-sectional shape when the values of the welding current Ik and the welding speed Vk are determined so that the welding bead cross-sectional shape becomes the maximum within the appropriate range that does not cause poor welding similarly is shown in FIG. Are represented by areas of alphanumeric characters 5A and 5B. In this embodiment, the welding current Ik and the welding speed Vk that maximize the weld bead cross-sectional shape are selected in the welding condition determination step in this embodiment.

  Therefore, in this embodiment, in addition to the same effect as the effect (1) of the first embodiment, the following effect (4) is obtained.

  (4) Since the weld bead cross-sectional area is maximized in the welding pass in any order in the layers from the third layer to the last layer, the number of weld passes of the weld joint 2 as a whole is poor. The minimum number is sufficient within an appropriate range of welding conditions that do not occur. Since the residual deformation value and the residual stress value are caused by plastic deformation due to heat input during welding, reducing the number of heat inputs leads to a reduction in the residual deformation value and the residual stress value. From this, it becomes possible to optimize the number of welding passes for the purpose of reducing the residual deformation value and the residual stress value before welding, and the optimum welding conditions can be selected.

  As mentioned above, although this invention was demonstrated based on each above-mentioned embodiment, this invention is not limited to this. For example, in each embodiment, the welding optimization method and the welding method of the welded structure using arc welding in the V-shaped joint groove of the butt joint have been described. However, the present invention is not limited to this. The present invention can also be applied to types and joint groove shapes.

  DESCRIPTION OF SYMBOLS 1A, 1B ... Thick plate (welded structure), 2 ... Welded joint part, 3 ... Joint groove, 10 ... Automatic welding machine (automatic welding apparatus), 14 ... Welding condition database, 15 ... Weld optimization system, 16 ... Displacement sensor, 17 ... temperature sensor, 18 ... weld record database, 19 ... basic analysis model generation means, 20 ... welding condition determination means, 21 ... welding deformation analysis means, 22 ... index determination means, 23 ... data recording means, 24 ... basic analysis model, 25 ... bead analysis model, 26 ... analysis model.

Claims (12)

A welding optimization method for optimizing a welding design for performing a plurality of welding passes on a joint groove formed in a welded joint portion of a welded structure,
For the welded structure, a basic analysis model generation step for generating a basic analysis model according to the type of joint of the welded joint portion and the shape of the joint groove;
Welding conditions of the welding pass in any order are determined within an appropriate range that does not cause welding failure in consideration of welding deformation of the joint groove shape caused by the welding path made before that, and based on this welding condition , A welding condition determination step for obtaining the weld bead cross-sectional shape of the welding pass in any order,
The weld bead cross-sectional shape of the arbitrary order of welding passes is converted into an analytical model and added to the basic analysis model, and the joint generated by the arbitrary order of welding passes is added using the added analytical model. A welding deformation analysis step for obtaining a weld deformation of a groove shape by thermal elastic-plastic analysis;
After the welding condition etc. determining step and the welding deformation analyzing step are executed for another order of welding passes, the welding analysis of the welded joint portion is completed and the number of weld passes is determined, and then the determination index value for the welded joint portion And determining whether or not the determination index value is within the allowable range. If the determination index value is not within the allowable range, the welding condition including the type of the joint and the shape of the joint groove is changed and the basic An index determination step for executing the analysis model generation step, the welding condition determination step and the welding deformation analysis step again;
Data for recording and storing the type of joint, the shape of the joint groove, the number of welding passes, and the welding conditions of each welding pass in the analysis result database when the judgment index value in this index judgment step is within an allowable range. A welding optimization method comprising: a recording step. 2. The optimum welding according to claim 1, wherein the step of determining the welding conditions and the like selects and determines the welding conditions in an arbitrary order of welding paths from a welding record database in which actual welding execution information is stored in advance. Method. The welding optimization method according to claim 1, wherein the determination index value used in the index determination step is a residual deformation value of the weld joint after completion of welding analysis, which is obtained by thermoelastic-plastic analysis. The welding optimization method according to claim 1, wherein the determination index value used in the index determination step is a residual stress value of a welded joint after completion of welding analysis, which is obtained by thermoelastic-plastic analysis. The welding optimization method according to claim 1, wherein in the determination step of welding conditions and the like, welding conditions in an arbitrary order of welding passes are determined from a weld defect analysis based on a mechanical model. In the step of determining welding conditions and the like, the welding bead cross-sectional shape in a welding pass in an arbitrary order is determined from heat transfer analysis using a heat conduction equation under conditions of welding current, welding voltage, and welding speed. The welding optimization method according to claim 1. 2. The welding optimization method according to claim 1, wherein in the determination step of welding conditions and the like, temperature history data corresponding to welding conditions in an arbitrary order of welding passes is obtained by heat transfer analysis using a heat conduction equation. . 2. The welding optimization method according to claim 1, wherein in the determination step of welding conditions and the like, the welding conditions in an arbitrary order of welding passes are determined so that a cross-sectional area of the welding passes in the order becomes a maximum. The actual welding work is carried out according to the type of joint obtained by the welding optimization method according to any one of claims 1 to 8, the shape of the joint groove, the number of welding passes, and the welding conditions of each welding pass. Features a welding method. When the welding is actually performed using an automatic welding device, the type of joint obtained by the welding optimization method, the shape of the joint groove, the number of welding passes, and the welding conditions of each welding pass are determined by the automatic welding device. The welding method according to claim 9, wherein the welding method is used as input data. When actually carrying out the welding, the welding pass position and the joint groove shape welding deformation measurement means, and the temperature history at the time of execution of each welding pass, using the means to measure the temperature history during the welding was actually welded The welding method according to claim 9, wherein the welding path position information, the welding deformation information of the joint groove shape, and the temperature history information are stored in the welding record database together with the welding conditions for all the welding paths. A welding optimization system for optimizing a welding design for performing a plurality of welding passes on a joint groove formed in a welded joint portion of a welded structure,
For the welded structure, basic analysis model generation means for executing a basic analysis model generation step for generating a basic analysis model according to the type of joint of the welded joint portion and the shape of the joint groove;
Welding conditions of the welding pass in any order are determined within an appropriate range that does not cause welding failure in consideration of welding deformation of the joint groove shape caused by the welding path made before that, and based on this welding condition Welding condition etc. determining means for executing a welding condition etc. determining step for obtaining the weld bead cross-sectional shape of the welding pass in this order;
The weld bead cross-sectional shape of the arbitrary order of welding passes is converted into an analytical model and added to the basic analysis model, and the joint generated by the arbitrary order of welding passes is added using the analysis model obtained by the addition. Welding deformation analysis means for executing a welding deformation analysis step for obtaining a weld deformation of a groove shape by thermoelastic-plastic analysis;
After the welding condition etc. determining step and the welding deformation analyzing step are executed for another order of welding passes, the welding analysis of the welded joint portion is completed and the number of weld passes is determined, and then the determination index value for the welded joint portion And determining whether or not the determination index value is within the allowable range. If the determination index value is not within the allowable range, the welding condition including the type of the joint and the shape of the joint groove is changed and the basic An index determination means for executing an index determination step for executing the analysis model generation step, the welding condition determination step, and the welding deformation analysis step again;
Data for recording and storing the type of joint, the shape of the joint groove, the number of welding passes, and the welding conditions of each welding pass in the analysis result database when the judgment index value in this index judgment step is within an allowable range. And a data recording means for executing a recording step.

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