Pipeline backing welding process planning method based on cooperation of laser vision scanner and process knowledge base

Abstract

The invention discloses a pipeline backing welding process planning method based on cooperation of a laser vision scanner and a process knowledge base, and the core content comprises the steps: firstly, building an excellent backing welding forming size model and the process knowledge base based on an excellent welding seam evaluation standard; then, a laser vision scanner is used for scanning the groove, and the characteristics of each section of groove are obtained; and finally, the welding process parameters of each section are obtained based on the process parameter calculation model. Wherein the excellent welding seam size model can calculate the welding wire melting area, the groove high side base metal melting area and the more melting welding wire area of the groove low side compared with the high side required by the groove according to the gap and the unfitness of butt joint of each section obtained through scanning. The process knowledge base can automatically match the parameters in the welding process parameter calculation model according to the material, the pipe diameter and the wall thickness of the to-be-welded pipeline. Features extracted by a visual scanner are converted into variables in a calculation model through an excellent weld joint forming size model, parameters in the model are matched in cooperation with a process knowledge base, and accurate backing welding process parameter planning under the actual working condition is achieved.

Description

Technical Field

[0001] The present invention relates to the field of pipeline robot welding, and in particular to a pipeline base welding process planning method based on the collaboration of a laser vision scanner and a process knowledge base. Background Art

[0002] Pressure pipe welding is widely used in petrochemical, nuclear power and thermal power industries. Promoting robot welding is conducive to alleviating the current problems of high labor costs and insufficient welder resources. At present, the base welding of medium and thick wall pressure pipes is mainly based on manual teaching due to the problem of accuracy consistency of groove processing group, which has long existed problems such as high labor intensity and insufficient process adaptability.

[0003] The existing technology mainly carries out process parameter planning based on the process knowledge base, including reasoning methods based on cases, rules and models. Case-based reasoning, as the name implies, is a method of analogical reasoning based on past cases, while rule-based reasoning is a reasoning method that condenses the expert knowledge in the field and expresses it in the form of rules by knowledge engineers. The reasoning ability and accuracy of case reasoning and rule reasoning depend on the completeness and accuracy of the cases and rules in the knowledge base. However, due to the random changes in the pipeline groove team situation and the complexity of the mutual constraints of process parameters, the above reasoning methods have problems such as large case data volume and difficulty in rule formulation. There are also model reasoning methods that combine knowledge bases with neural networks or other machine learning methods, but because the neural network reasoning process is a "black box", users lack confidence in the results.

[0004] In recent years, the research on groove feature recognition using visual sensing technology has become relatively mature. It can realize accurate welding path planning and multi-layer and multi-pass planning for medium and thick plates in process planning. However, process parameter planning, especially base welding, is generally obtained through process tests, and there is a lack of ideal process parameter planning strategies.

[0005] In view of the shortcomings of the above-mentioned single strategy of visual guidance and process knowledge base, this paper proposes an intelligent process planning strategy that combines visual guidance and process knowledge base, and establishes a mathematical model for mapping actual groove size and welding process parameters. This model can effectively improve the efficiency and accuracy of welding process parameter planning under actual working conditions. Summary of the invention

[0006] The purpose of the present invention is to provide a pipeline root welding process planning method based on the collaboration of a laser vision scanner and a process knowledge base, which is used for planning the welding process parameters of petrochemical pipeline robot root welding.

[0007] The technical solution to achieve the purpose of the present invention is:

[0008] A pipeline base welding process planning method based on the collaboration of a laser vision scanner and a process knowledge base comprises the following steps:

[0009] Step 1: Build the pipeline intelligent welding hardware platform, including argon arc welding robot, laser vision scanner, main control computer, rotary positioner, robot control cabinet, wire feeding mechanism, shielding gas mechanism, and welding power supply.

[0010] Step 2: Drive the welding robot guide rail to move the welding gun to the position of the groove to be welded, which is 10-20° vertical to the pipeline, and adjust the welding gun posture so that the welding gun is perpendicular to the tangent position of the groove to be welded, and adjust the distance between the end of the welding wire and the bottom of the groove to 2-3mm.

[0011] Step 3: Use the constructed platform to conduct welding experiments to obtain welding process parameters and corresponding forming size data. At the same time, establish an "excellent weld evaluation standard" based on the forming size and stress concentration of the back of the pipeline weld to select excellent welds, and then establish an excellent base weld forming size model and a corresponding process knowledge base based on the excellent welds.

[0012] Furthermore, the "Excellent Weld Evaluation Criteria" include:

[0013] First, based on the forming size of the base weld, a "forming size rating standard" is established, which sets four levels for the forming size rating, including back reinforcement, bottom weld width and weld height. Among them, the back reinforcement is the distance from the low side groove to the lowest point of the weld, the bottom weld width is the horizontal distance between the bottom welds of the grooves on both sides, and the weld height is the vertical distance from the lowest point of the weld on the upper surface of the base weld to the lowest point on the lower surface.

[0014] For back reinforcement, A, B, C and D are 0-1mm, 1-2mm, 2-3mm and above 3mm respectively; the accumulation bottom weld width rating is as follows

[0015]

[0016] Where, d is the groove gap;

[0017] The weld height ratings are shown below

[0018]

[0019] Among them, η is the misalignment of the groove;

[0020] The excellent weld formation dimensions need to meet the following requirements: the score must contain A and D cannot appear. When the score contains one A, the other two scores must be above C. When the score contains two A's, the other score can be C or above.

[0021] Secondly, excellent welds are further selected based on the stress concentration degree of the welds. Based on the asymmetry of the back weld of the base weld, the stress concentration factor (SCF) on both sides of the back weld of the base weld is calculated respectively, and the maximum value is taken as the stress concentration factor of the base weld.

[0022] The stress concentration factor calculation formula is as follows

[0023]

[0024] Where r1 and r2 are the arc transition radii at the weld toes on both sides of the back; θ1 and θ2 are the weld toe angles on the low side and high side of the back; δ is the pipe wall thickness; W b h is the back width of the weld, which is the distance between the two weld roots; b is the weld back side height, perpendicular to W b ;h b1 、h b2 They are the back reinforcement heights of the low side and high side of the groove respectively. The values ​​of k0, K1, K2 and K3 are 0.3, 0.3, 0.3 and 0.33 respectively.

[0025] The weld is ultimately defined as an excellent weld if the calculated stress concentration factor satisfies SCF≤2.0.

[0026] Furthermore, the establishment of an excellent weld forming dimension model based on the excellent weld includes:

[0027] First, the upper surface of an excellent weld is parabolic, which satisfies y=ax 2 The lower surface is two asymmetric right-angle trapezoids, and the angle of the high side trapezoid of the groove is defined as θ p2 , the trapezoidal angle of the lower side of the groove is θ p1 , the height of the weld on the high side of the groove is H, the weld width on the back of the weld is D, and the residual height on the low side of the back of the weld is h b1 , the weld back high side excess height is h b2 .

[0028] Among them, H, D, h b1 、h b2 is a constant determined by the rating standard; a, θ p2 ,θ p1 is a constant and is related to the base material. For carbon steel, a=0.113, θ p2 =32.68°,θ p1 =25.91°.

[0029] Secondly, a coordinate system is established for the model, and a calculation model is established for the melting area of ​​welding wire, the melting area of ​​base material, and the melting area of ​​welding wire that is more on the low side of the groove than on the high side of the groove.

[0030] The calculation formula of welding wire melting area is as follows:

[0031]

[0032] S H =S H1 +S H2

[0033] Where S H , S H1 , S H2 They respectively represent the melting area of ​​welding wire, the melting area of ​​welding wire above the groove, and the melting area of ​​welding wire below the groove; n2 and n1 respectively represent the horizontal coordinates of the intersection of the upper surface of the weld and the two sides of the groove, and m is the vertical coordinate of the intersection of the upper surface of the weld and the two sides of the groove; the specific values ​​of n2, n1, and m can be solved by jointly solving the curve function expression of the upper surface of the weld and the straight line function expression of the two sides of the groove.

[0034] Then, based on the fact that the asymmetry of the weld size leads to different areas of molten wire on both sides, the calculation formula for the area of ​​more molten wire on the low side of the groove than on the high side of the groove is established as follows:

[0035]

[0036] S Hd =S Hd2 -S Hd1

[0037] Where S Hd , S Hd2 , S Hd1 They respectively represent the area of ​​more molten welding wire required on the low side of the groove than on the high side of the groove, the area enclosed by the upper surface of the weld and the low side of the groove, and the area enclosed by the upper surface of the weld and the dotted line parallel to the low side of the groove.

[0038] Finally, the results of the parent metal melting area of ​​the excellent weld need to be fitted. From the fitting results of the parent metal melting area on the low side and high side of the groove of the excellent weld, it can be seen that the parent metal melting area on the high side of the groove is a constant value S M , and the melting area of ​​the low side groove is more than 70% of the melting area of ​​the parent material on the high side of the groove. M =12.31mm 2 .

[0039] Furthermore, the welding process knowledge base is presented in a table form, and can automatically match the following three process parameter calculation models of groove low side residence time, welding current, and wire feeding speed, as well as the groove high side residence time t0 and welding speed V according to the pipe material, pipe diameter, and wall thickness. W, the parameters include b1, b2 and a2 / a1, and the specific values ​​of these parameters are obtained by fitting the process parameters of excellent welds with weld size data into the welding current calculation model and the wire feeding speed calculation model; and the groove high side residence time and welding speed are only adjusted according to the parent material during the process experiment, so the groove high side residence time and welding speed in the process knowledge base are only related to the material. For carbon steel pipes, t0 = 0.2S, V W =0.14m / min.

[0040] The fitting of b1 and b2 can be carried out in the following manner: 10 to 20 groups of excellent welds are selected for pipes of different materials, diameters and wall thicknesses, preferably an even number of groups; the process parameters corresponding to these excellent welds, as well as the melting area of ​​the base material on the high side of the groove, the area of ​​the more molten welding wire required on the low side of the groove than on the high side of the groove, and the melting area of ​​the welding wire are substituted into the following welding current calculation model; the numerical solutions of 5 to 10 groups of b1 and b2 are obtained by combining them in pairs; the average of the 5 to 10 groups of b1 and b2 is obtained, which is the numerical value of b1 and b2 of the process knowledge base corresponding to the pipe of this material, diameter and wall thickness.

[0041] The fitting of a2 / a1 can be carried out as follows: 10-20 groups of excellent welds are selected for pipes of different materials, and the process parameters corresponding to the excellent welds and the values ​​of the melting area of ​​the welding wire are substituted into the following wire feeding speed calculation model. After solving, the numerical solutions of 10-20 groups of a2 / a1 are obtained, and the average of the 10-20 groups of a2 / a1 is obtained, which is the value of a2 / a1 in the process knowledge base corresponding to the pipe of this material.

[0042] Step 4: Adjust the welding platform according to step 2. Then start the laser vision scanner, and the rotary positioner drives the pipe to rotate one circle from 0° at 1-2° / s to scan the groove features. After the scanning is completed, the groove feature parameters are fitted at 5-10° each section.

[0043] The groove characteristic parameters include misalignment (η) and gap (d).

[0044] Step 5: Using the base material as input, match the welding speed and the dwell time on the high side of the groove from the process knowledge base.

[0045] Step 6: Using the triangular swing mode, substitute the gap of each groove into the swing amplitude and swing length calculation model to obtain the swing amplitude and swing length parameters.

[0046] Furthermore, the swing amplitude and swing length calculation model includes: the swing length and swing amplitude calculation formula of each groove section is as follows:

[0047]

[0048] l=l w +0.1

[0049] Among them l w is the swing amplitude and l is the swing length.

[0050] Step 7: Substitute the gap and misalignment of each groove into the excellent base welding forming size model to calculate the area of ​​more molten welding wire required on the low side of the groove than on the high side of the groove, and select the corresponding groove low side residence time calculation model based on the area of ​​more molten welding wire required.

[0051] Furthermore, the mathematical expression formula of the groove low side residence time calculation model is as follows:

[0052]

[0053] Where η0 represents the thermal efficiency of tungsten inert gas welding, S Hd0 It is the area of ​​the welding wire required to melt more on the low side of the groove than on the high side of the groove when the melting area of ​​the base metal on the low side of the groove is 70% of the melting area of ​​the base metal on the high side of the groove. The calculation formula is as follows:

[0054] b2S Hd0 =0.3b1S M

[0055] Step 8: Substitute the groove gap and misalignment of each section into the excellent root welding forming size model to calculate the required melting wire area S for each section H The base material, model and pipe thickness are used as input conditions. With the help of the process knowledge base, b1 and b2 are matched. The b1 and b2 values ​​are substituted into the welding current calculation model. The b2 value is substituted into the groove low side residence time calculation model. The welding current calculation model and the groove low side residence time calculation model are combined to calculate each section of the welding current and the groove low side residence time.

[0056] Furthermore, the welding current calculation model is established based on the principle of conservation of heat input energy, and its mathematical expression formula is as follows:

[0057] When S hd ≤S Hd0 When the heat input energy conservation equation is

[0058]

[0059] When S hd >S Hd0 When the heat input energy conservation equation is

[0060] η0UIT=(1.7b1S M +b2S H )

[0061] Where U is the welding voltage, T is the period under one swing, and the calculation formula is as follows:

[0062]

[0063] Among them, T L and T R They represent the dwell time on the left side of the groove and the dwell time on the right side of the groove, i.e., the dwell time on the low side of the groove and the dwell time on the high side of the groove mentioned above; when S Hd ≤S Hd0 , at this time, t L =t R = t0 is directly substituted into the above welding current calculation model to calculate the welding current. When S Hd >S Hd0 When the groove is low side, it is necessary to combine the above groove low side residence time calculation model and welding current calculation model to solve the groove low side residence time and welding current.

[0064] The mathematical expression of the combined calculation model is as follows:

[0065]

[0066] Step 9: Substitute the gap and misalignment of each groove into the excellent root welding forming size model to calculate the required molten wire area S H The base material is used as the input condition, and a2 / a1 is matched with the process knowledge base. The a2 / a1 value is substituted into the wire feeding speed calculation model to calculate the wire feeding speed.

[0067] The wire feeding speed calculation model is established by the mass conservation equation, and its mathematical expression formula is as follows:

[0068] V 1 f T=a2S H l

[0069] Compared with the prior art, the present invention has the following significant advantages: 1) an "excellent weld evaluation standard" is established based on the pipeline back forming size rating and stress concentration to ensure the rationality of sample selection; 2) a welding process parameter calculation model is established based on the heat input energy conservation equation and the mass conservation equation to ensure the accuracy of process parameter calculation; 3) a pipeline base welding process planning strategy based on the collaboration of a laser visual scanner and a process knowledge base can realize the automatic generation of process parameters under actual working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a flow chart of a pipeline base welding process planning method based on the collaboration of a laser vision scanner and a process knowledge base of the present invention.

[0071] Figure 2 This is a device diagram of a pipeline base welding process planning method based on the collaboration of a laser visual scanner and a process knowledge base according to the present invention.

[0072] Figure 3 This is a schematic diagram of the excellent weld formation size model corresponding to the DN300, 11mm thick carbon steel pipe of grade Q235.

[0073] Figure 4 It is a partial screenshot of a process knowledge base established by a pipeline base welding process planning method based on the collaboration of a laser vision scanner and a process knowledge base in the present invention. DETAILED DESCRIPTION

[0074] The present invention is further described below with reference to the accompanying drawings of the specification and using a DN300, 11 mm thick carbon steel pipe of grade Q235. The specific process is as follows: Figure 1 shown.

[0075] Follow the steps below to implement it:

[0076] Step 1: Build a pipeline intelligent welding hardware platform, including an argon arc welding robot 1, a laser vision scanner 2, a main control machine 3, a rotary positioner 4, a robot control cabinet 5, a wire feeding mechanism 6, a shielding gas mechanism 7, and a welding power source 8.

[0077] The laser vision scanner 2 is mounted at the end of the argon arc welding robot 1 to scan and extract the groove features of each section of the pipeline. The scanned groove features are transmitted to the process knowledge base in the main control computer 3 to obtain the process parameters of each section. The main control computer can transmit the process parameters of each section to the robot control cabinet 5 to control the argon arc welding robot 1 integrated with the wire feeding mechanism 6, the shielding gas mechanism 7, and the welding power supply 8 to complete the actual pipeline welding work.

[0078] Step 2: Drive the welding robot guide rail to move the welding gun to the groove position to be welded, which is 20° perpendicular to the pipeline, and adjust the posture of the welding gun to A: 179.09B: 68.97C: -0.46, and adjust the distance between the end of the welding wire and the bottom of the groove to 2mm;

[0079] Step 3: Conduct a large number of welding experiments and establish "excellent weld evaluation criteria" based on the back forming size and stress concentration of the pipeline weld to select excellent welds, and then establish the following criteria based on the excellent welds: Figure 3 The excellent weld formation size model and the corresponding process knowledge base are shown.

[0080] Figure 4 A partial screenshot of the process knowledge base is given.

[0081] Furthermore, the "Excellent Weld Evaluation Criteria" include:

[0082] First, based on the forming size of the base weld, a "forming size rating standard" is established. This standard includes the forming size rating, including back reinforcement, bottom weld width and weld height. Among them, the back reinforcement is the distance from the low side groove to the lowest point of the weld, the bottom weld width is the horizontal distance between the bottom welds of the grooves on both sides, and the weld height is the vertical distance from the lowest point of the weld on the upper surface of the base weld to the lowest point on the lower surface.

[0083] The bottom weld size rating standard includes 4 levels. For the back reinforcement, A, B, C and D are 0-1mm, 1-2mm, 2-3mm and above 3mm respectively; the accumulation bottom weld width rating is as follows

[0084]

[0085] Where d is the groove gap.

[0086] The weld height ratings are shown below

[0087]

[0088] Among them, η is the misalignment of the groove.

[0089] The excellent weld formation dimensions need to meet the following requirements: the score must contain A and D cannot appear. When the score contains one A, the other two scores must be above C. When the score contains two A's, the other score can be C or above.

[0090] Secondly, excellent welds are further selected based on the stress concentration degree of the welds. Based on the asymmetry of the back weld of the base weld, the stress concentration factor (SCF) on both sides of the back weld of the base weld is calculated respectively, and the maximum value is taken as the stress concentration factor of the base weld.

[0091] The stress concentration factor calculation formula is as follows

[0092]

[0093] Where r1 and r2 are the arc transition radii at the weld toes on both sides of the back; θ1 and θ2 are the weld toe angles on the low side and high side of the back; δ is the pipe wall thickness; W b h is the back width of the weld, which is the distance between the two weld toes; b is the weld back side height, perpendicular to W b ;h b1 、h b2 They are the back reinforcement heights of the low side and high side of the groove respectively. The values ​​of k0, K1, K2 and K3 are 0.3, 0.3, 0.3 and 0.33 respectively.

[0094] A weld with a stress concentration factor of SCF≤2.0 is defined as an excellent weld.

[0095] Furthermore, the establishment of an excellent weld forming dimension model based on the excellent weld includes:

[0096] First, the upper surface of the excellent weld of the carbon steel pipeline is fitted as a parabola, which conforms to y = 0.113x 2 The lower surface is two asymmetric right-angle trapezoids, and the angle of the trapezoid on the high side of the groove is θ p2 is 32.68°, and the trapezoidal angle θ on the lower side of the groove p1 is 25.91°, the height of the weld on the high side of the groove is (H), the weld width on the back of the weld is (D), and the residual height on the low side of the back of the weld is (h b1 ), the weld back high side excess height is (h b2 ).

[0097] Among them, H, D, h b1 、h b2 is a constant determined by the rating standard;

[0098] Secondly, a coordinate system is established for the model, and a calculation model is established for the melting area of ​​welding wire, the melting area of ​​base material, and the melting area of ​​welding wire that is more on the low side of the groove than on the high side of the groove.

[0099] The calculation formula of welding wire melting area is as follows:

[0100]

[0101] S H =S H1 +S H2

[0102] Where S H , S H1 , S H2 They respectively represent the melting area of ​​welding wire, the melting area of ​​welding wire above the groove, and the melting area of ​​welding wire below the groove; n2 and n1 respectively represent the horizontal coordinates of the intersection of the upper surface of the weld and the two sides of the groove, and m is the vertical coordinate of the intersection of the upper surface of the weld and the two sides of the groove; the specific values ​​of n2, n1, and m can be solved by jointly solving the curve function expression of the upper surface of the weld and the straight line function expression of the two sides of the groove.

[0103] Then, based on the fact that the asymmetry of the weld size leads to different areas of molten wire on both sides, the calculation formula for the area of ​​more molten wire on the low side of the groove than on the high side of the groove is established as follows:

[0104]

[0105] S Hd =S Hd2 -S Hd1

[0106] Where S Hd , SHd2 , S Hd1 They respectively represent the area of ​​more molten welding wire required on the low side of the groove than on the high side of the groove, the area enclosed by the upper surface of the weld and the low side of the groove, and the area enclosed by the upper surface of the weld and the dotted line parallel to the low side of the groove.

[0107] Finally, from the fitting results of the parent metal melting area of ​​the excellent weld of the carbon steel pipeline, it can be known that the parent metal melting area S on the high side of the groove is M =12.31mm 2 , and the melting area of ​​the low side groove is more than 70% of the melting area of ​​the parent material on the high side of the groove.

[0108] Furthermore, the welding process knowledge base is presented in a table form, and can automatically match the following three process parameter calculation models of groove low side residence time, welding current, and wire feeding speed, as well as the groove high side residence time t0 and welding speed V according to the pipe material, pipe diameter, and wall thickness. W , parameters include b1, b2 and a2 / a 1， The specific values ​​of these parameters are obtained by fitting the process parameters of excellent welds with weld size data into the welding current calculation model and the wire feeding speed calculation model; the high side dwell time and welding speed of the groove are only adjusted according to the parent material during the process experiment. For carbon steel pipes, t0 = 0.2S, V W =0.14m / min.

[0109] Through matching the process knowledge base, the DN300, 11mm thick carbon steel pipe with brand Q235 was obtained with b1=29.52957, b2=30.75997, and a2 / a1=1.5323.

[0110] Step 4: Build the welding platform according to step 2. Then start the laser vision scanner, and the rotary positioner drives the pipe to rotate one circle from 0° at 1-2° / s to scan the groove features. After the scanning is completed, the groove feature parameters are fitted at 5-10° each section.

[0111] The groove characteristic parameters include misalignment (η) and gap (d).

[0112] Step 5: Using the base material carbon steel as input, match the welding speed V from the process knowledge base W =0.14m / min, the dwell time on the high side of the groove t0 =0.2S.

[0113] Step 6: Using the triangular swing mode, substitute the gap of each groove into the swing amplitude and swing length calculation model to obtain the swing amplitude and swing length parameters.

[0114] Furthermore, the swing amplitude and swing length calculation model includes: the swing length and swing amplitude calculation formula of each groove section is as follows:

[0115]

[0116] l=l w +0.1

[0117] Among them l w is the swing amplitude and l is the swing length.

[0118] Step 7: Substitute the gap and misalignment of each groove into the excellent base welding forming size model to calculate the area of ​​more molten welding wire required on the low side of the groove than on the high side of the groove, and select the corresponding groove low side residence time calculation model based on the area of ​​more molten welding wire required.

[0119] Furthermore, the mathematical expression formula of the groove low side residence time calculation model is as follows:

[0120]

[0121] Where η0 represents the thermal efficiency of tungsten inert gas arc welding, 3.55 is the DN300 of Q235 brand, and when the melting area of ​​the base material on the lower side of the groove of an 11mm thick carbon steel pipe is 70% of the melting area of ​​the base material on the higher side of the groove, the area of ​​the melting wire required on the lower side of the groove is more than that on the higher side of the groove.

[0122] Step 8: Substitute the groove gap and misalignment of each section into the excellent root welding forming size model to calculate the required melting wire area S for each section H The base material Q235 carbon steel, model DN300 and pipe thickness 11mm are used as input conditions. With the help of process knowledge base matching b1=29.52957 and b2=30.75997, the b1 and b2 values ​​are substituted into the welding current calculation model, and the b2 value is substituted into the groove low side residence time calculation model. The welding current calculation model and the groove low side residence time calculation model are combined to calculate each section of welding current and groove low side residence time.

[0123] Furthermore, the welding current calculation model is established based on the principle of conservation of heat input energy, and its mathematical expression formula is as follows:

[0124] When S hd When ≤3.55, the heat input energy conservation equation is:

[0125]

[0126] When S hd When >3.55, the heat input energy conservation equation is

[0127] η0UIT=(50.20027*S M +30.75997*S H )

[0128] Where U is the welding voltage, T is the period under one swing, and the calculation formula is as follows:

[0129]

[0130] Among them, T L and T R They represent the dwell time on the left side of the groove and the dwell time on the right side of the groove, i.e., the dwell time on the low side of the groove and the dwell time on the high side of the groove mentioned above; when S Hd ≤S Hd0 , at this time, t L =t R = 0.2S directly substitute into the above welding current calculation model to calculate the welding current. When S Hd >S Hd0 When the groove is low side, it is necessary to combine the above groove low side residence time calculation model and welding current calculation model to solve the groove low side residence time and welding current.

[0131] The mathematical expression of the combined calculation model is as follows:

[0132]

[0133] Step 7: Substitute the gap and misalignment of each groove into the excellent root welding forming size model to calculate the required melting wire area (S H ), and taking the base material as the input condition, with the help of the process knowledge base matching a2 / a1=1.5323, the a2 / a1 value is substituted into the wire feeding speed calculation model to calculate the wire feeding speed.

[0134] The wire feeding speed calculation model is established by the mass conservation equation, and its mathematical expression formula is as follows:

[0135] V f T=1.5323*S H l.

Claims

1. A pipeline base welding process planning method based on the collaboration of laser vision scanner and process knowledge base, characterized in that: The following steps are involved: Step 1: Build a pipeline intelligent welding hardware platform, including argon arc welding robot, laser vision scanner, main control machine, rotary positioner, robot control cabinet, wire feeding mechanism, shielding gas mechanism, and welding power supply; Step 2: Drive the welding robot guide rail to move the welding gun to the position of the groove to be welded, which is 10-20° vertical to the pipeline, and adjust the welding gun posture so that the welding gun is perpendicular to the tangent position of the groove to be welded, and adjust the distance between the end of the welding wire and the bottom of the groove to 2-3mm; Step 3: Use the built platform to conduct welding experiments to obtain welding process parameters and corresponding forming size data. At the same time, establish "excellent weld evaluation criteria" based on the back forming size and stress concentration of the pipeline weld to select excellent welds, and then establish an excellent base welding forming size model and corresponding process knowledge base based on the excellent welds; Step 4: Adjust the welding platform according to step 2; then start the laser vision scanner, and the rotary positioner drives the pipe to rotate one circle from 0° at 1-2° / s to scan the groove features. After the scanning is completed, the groove feature parameters are obtained at each section of 5-10°; Step 5: Using the base material as input, match the welding speed and the dwell time on the high side of the groove from the process knowledge base; Step 6: Using the triangle swing mode, substitute the gap of each groove into the swing amplitude and swing length calculation model to obtain the swing amplitude and swing length parameters; Step 7: Substitute the gap and misalignment of each groove into the excellent root welding forming size model, calculate the area of ​​more melting wire required on the low side of the groove than on the high side of the groove, and select the corresponding groove low side residence time calculation model based on the area of ​​more melting wire required; Step 8: Substitute the groove gap and misalignment of each section into the excellent root welding forming size model to calculate the required melting wire area S for each section H The base material, model and pipe thickness are used as input conditions, b1 and b2 are matched with the process knowledge base, b1 and b2 values ​​are substituted into the welding current calculation model, b2 value is substituted into the groove low side dwell time calculation model, and the welding current calculation model and the groove low side dwell time calculation model are combined to calculate each section of welding current and groove low side dwell time; Step 9: Substitute the gap and misalignment of each groove into the excellent root welding forming size model to calculate the required molten wire area S H The base material is used as the input condition, and a2 / a1 is matched with the process knowledge base. The a2 / a1 value is substituted into the wire feeding speed calculation model to calculate the wire feeding speed.

2. The pipeline base welding process planning method based on the collaboration of laser vision scanner and process knowledge base according to claim 1 is characterized in that: The "Excellent Weld Evaluation Criteria" described in Step 3 include: Firstly, based on the forming size of the base weld, a "forming size rating standard" is established, which sets four levels for back reinforcement, bottom weld width and weld height. Among them, back reinforcement is the distance from the lower side groove to the lowest point of the weld, bottom weld width is the horizontal distance between the bottom welds of the grooves on both sides, and weld height is the vertical distance from the lowest point of the weld on the upper surface of the base weld to the lowest point on the lower surface. For the back reinforcement, A, B, C and D are 0-1mm, 1-2mm, 2-3mm and above 3mm respectively; the bottom weld width rating is as follows: Where, d is the groove gap; The weld height ratings are as follows: Among them, η is the misalignment of the groove; Excellent weld formation dimensions must meet the following requirements: the score must contain A and cannot contain D. When the score contains one A, the other two scores must be above C. When the score contains two A's, the other score can be C or above. Secondly, excellent welds are further selected based on the stress concentration degree of the welds; based on the asymmetry of the back weld of the base weld, the stress concentration factors SCF on both sides of the back weld of the base weld are calculated respectively, and the maximum value is taken as the stress concentration factor of the base weld; The stress concentration factor calculation formula is as follows Where r1 and r2 are the arc transition radii at the weld toes on both sides of the back; θ1 and θ2 are the weld toe angles on the low side and high side of the back; δ is the pipe wall thickness; W b h is the back width of the weld, which is the distance between the two weld toes; b is the weld back side height, perpendicular to W b ;h b1 、h b2 are the back reinforcement of the low side and high side of the groove, and the values ​​of k0, K1, K2 and K3 are 0.3, 0.3, 0.3 and 0.33 respectively; The weld is ultimately defined as an excellent weld if the calculated stress concentration factor satisfies SCF≤2.

0.

3. The pipeline base welding process planning method based on the collaboration of laser vision scanner and process knowledge base according to claim 1 is characterized in that: The establishment of an excellent root pass welding forming size model based on an excellent weld described in step 3 includes: First, the upper surface of an excellent weld is parabolic, which satisfies y=ax 2 The lower surface is two asymmetric right-angle trapezoids, and the angle of the high side trapezoid of the groove is defined as θ p2 , the trapezoidal angle of the lower side of the groove is θ p1 , the distance from the lowest point of the parabola on the upper surface of the bottom weld to the bottom surface of the high side groove is H, the weld width on the back of the weld is D, and the residual height on the low side of the back of the weld is h b1 , the weld back high side excess height is h b2 ; Among them, H, D, h b1 、h b2 is a constant, determined by the rating standard; a, θ p2 ,θ p1 is a constant, which is related to the parent material; for carbon steel, a=0.113, θ p2 =32.68°,θ p1 =25.91°; Secondly, a coordinate system is established for the model and a calculation model is established for the melting area of ​​welding wire, the melting area of ​​base material, and the area of ​​welding wire that is more molten on the lower side of the groove than on the higher side of the groove; The calculation formula of welding wire melting area is as follows: S H =S H1 +S H2 Among them, S H , S H1 , S H2 They represent the melting area of ​​welding wire, the melting area of ​​welding wire above the groove, and the melting area of ​​welding wire below the groove respectively; n2 and n1 represent the abscissa of the intersection of the upper surface of the weld and the two sides of the groove respectively, and m represents the ordinate of the intersection of the upper surface of the weld and the two sides of the groove; the specific values ​​of n2, n1, and m can be solved by combining the curve function expression of the upper surface of the weld and the straight line function expression of the two sides of the groove; Then, based on the fact that the asymmetry of the weld size leads to different areas of molten wire on both sides, the calculation formula for the area of ​​more molten wire on the low side of the groove than on the high side of the groove is established as follows: S Hd =S Hd2 -S Hd1 Among them, S Hd , S Hd2 , S Hd1 They respectively represent the area of ​​more molten welding wire required on the lower side of the groove than on the higher side of the groove, the area enclosed by the upper surface of the weld and the lower side of the groove, and the area enclosed by the upper surface of the weld and the dotted line parallel to the lower side of the groove; Finally, it is also necessary to fit the results of the parent material melting area of ​​the excellent weld. From the fitting results of the parent material melting area on the low side and high side of the groove of the excellent weld, it can be seen that the parent material melting area on the high side of the groove is a constant value S M , and the melting area of ​​the low side groove is more than 70% of the melting area of ​​the parent material on the high side of the groove; for carbon steel pipes S M =12.31mm 2 。 4. The pipeline base welding process planning method based on the collaboration of laser vision scanner and process knowledge base according to claim 1 is characterized in that: The process knowledge base based on excellent welds described in step 3 includes: The welding process knowledge base includes pipe material, pipe diameter, wall thickness, and the corresponding groove high side dwell time t0 and welding speed V W , also includes parameters b1, b2 and a2 / a1 in the three process parameter calculation models of groove low side dwell time, welding current and wire feeding speed. Based on the pipe material, pipe diameter and wall thickness, the corresponding groove high side dwell time t0 and welding speed V can be automatically matched. W As well as the parameters in the calculation model of three process parameters: dwell time on the low side of the groove, welding current, and wire feeding speed.

5. The pipeline base welding process planning method based on the collaboration of laser vision scanner and process knowledge base according to claim 1 is characterized in that: The swing amplitude and swing length calculation model described in step 6 includes: The calculation formula for the swing length and swing amplitude of each groove is as follows: l＝l w +0.1 Among them l w is the swing amplitude and l is the swing length.

6. The pipeline base welding process planning method based on the collaboration of laser vision scanner and process knowledge base according to claim 1 is characterized in that: The calculation model for selecting the corresponding groove low side dwell time based on the required area size of the multi-melting welding wire in step 7 includes: The mathematical expression formula of the groove low side residence time calculation model is as follows: Among them, η0 represents the thermal efficiency of tungsten inert gas welding, S Hd0 It is the area of ​​the welding wire required to melt more on the low side of the groove than on the high side of the groove when the melting area of ​​the base metal on the low side of the groove is 70% of the melting area of ​​the base metal on the high side of the groove. The calculation formula is as follows: b2S Hd0 =0.3b1S M 。 7. The pipeline base welding process planning method based on the collaboration of laser vision scanner and process knowledge base according to claim 1 is characterized in that: The combined welding current calculation model and groove low side dwell time calculation model in step 8 calculate the welding current and groove low side dwell time, including: The welding current calculation model is based on the principle of conservation of heat input energy, and its mathematical expression formula is as follows: When S hd ≤S Hd0 When the heat input energy conservation equation is When S hd >S Hd0 When the heat input energy conservation equation is η0UIT=(1.7b1S M +b2S H ) Where U is the welding voltage, T is the period under one swing, and the calculation formula is as follows: Among them, T L and T R They represent the dwell time on the left side of the groove and the dwell time on the right side of the groove, i.e., the dwell time on the low side of the groove and the dwell time on the high side of the groove mentioned above; when S Hd ≤S Hd0 , at this time, t L =t R = t0 is directly substituted into the above welding current calculation model to calculate the welding current. When S Hd >S Hd0 When the groove is lowered, the groove lower side dwell time calculation model and welding current calculation model need to be combined to solve the groove lower side dwell time and welding current; The mathematical expression of the combined calculation model is as follows:

8. The pipeline base welding process planning method based on the collaboration of laser vision scanner and process knowledge base according to claim 1 is characterized in that: The wire feeding speed calculation model in step 9 includes: The wire feeding speed calculation model is established by the mass conservation equation, and its mathematical expression formula is as follows: a1V f T=a2S H l。

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