Full-process optimization control method for forming precision of pipe after welding and bending

Abstract

A full-process optimization control method for forming precision of a pipe by firstly welding and then bending comprises the following steps: after performing process pre-judgment according to the size of a target bent pipe fitting, calculating the bent pipe process parameters and the bent pipe unfolding size, manufacturing a straight pipe with a flange, and performing bent pipe forming treatment of real-time monitoring on the straight pipe with the flange. And real-time data of pipe forming precision indexes are measured, and iterative optimization is performed on pipe bending process parameters through a first-welding and second-bending pipe fitting bending process optimization method, so that the pipe forming precision indexes meet the requirements, and optimal control over the first-welding and second-bending forming precision of the pipes is achieved. According to the method, full-process forming precision regulation and control are carried out on the pipe welding-before-bending process including the working procedure steps of welding-before-bending feasibility judgment, bent pipe unfolding size calculation, bending process parameter determination, real-time correction optimization and the like, and high-quality and high-efficiency forming of welding-before-bending metal pipe bending is achieved; and the one-time forming precision of the bent pipe with the flange is effectively guaranteed, and important engineering application value and obvious economic benefits are achieved in the engineering fields related to bent pipe machining such as large ship manufacturing and aerospace.

Description

Technical Field

[0001] The present invention relates to a technology in the field of machining, specifically a full-process optimization control method for the forming accuracy of pipe materials with prior welding and subsequent bending. Background Art

[0002] Elbow components are widely used in fields such as aerospace, shipbuilding, and rail transit. In complex pipe systems, flange connection is the main method for elbow assembly. The traditional "bend first and then weld" process first forms the pipe fittings by bending, and then welds the flanges after manual fine-tuning. Although the accuracy requirements for the bending forming process are not high, the processing time is long. The "weld first and then bend" process first quickly welds the flanges in the straight pipe state and then performs bending forming. Although it effectively saves working hours, it puts forward higher requirements for the accuracy of the first bending forming. Therefore, it is necessary to accurately control the forming accuracy of the pipe materials with prior welding and subsequent bending throughout the whole process. Summary of the Invention

[0003] Aiming at the problem that the prior art does not carry out the full-process accuracy control of the manufacturing of elbow forming and cannot meet the requirements of the first forming accuracy of the prior welding and subsequent bending process, the present invention proposes a full-process optimization control method for the forming accuracy of pipe materials with prior welding and subsequent bending. The full-process forming accuracy of the pipe materials with prior welding and subsequent bending process, including process steps such as feasibility judgment of prior welding and subsequent bending, calculation of the developed size of the bent pipe, determination of bending process parameters, and real-time correction and optimization, is controlled. The high-quality and high-efficiency forming of the prior welding and subsequent bending of metal pipe materials is realized, effectively ensuring the accuracy of the first forming of the elbow with flanges, and having important engineering application value and obvious economic benefits in engineering fields such as large ship manufacturing and aerospace involving elbow processing.

[0004] The present invention is realized through the following technical solutions:

[0005] The present invention relates to a full-process optimization control method for the forming accuracy of pipe materials with prior welding and subsequent bending. After making a process prediction according to the dimensions of the target elbow fittings, the bending process parameters and the developed size of the bent pipe are calculated, and a straight pipe with flanges is fabricated. The bending forming process of the straight pipe with flanges is monitored in real time, the real-time data of the pipe forming accuracy index is measured, and the bending process parameters are iteratively optimized through the bending process optimization method for the prior welding and subsequent bending pipe fittings, so as to achieve the optimization control of the forming accuracy of the pipe materials with prior welding and subsequent bending while the pipe forming accuracy index meets the requirements.

[0006] The so-called process prediction means that when calculating that the dimensions of the target elbow fittings meet or min(l1, l2) > r, it is considered that the prior welding and subsequent bending treatment can be carried out, where: r is the bending radius, and l1 and l2 are the lengths of the straight pipe sections at both ends, that is, the total length of the straight pipe sections l = l1 + l2.

[0007] The dimensions of the target bent pipe fitting include: the outer diameter d, wall thickness t, target bending angle φ, bending radius r, straight pipe section lengths l1 and l2 at both ends, total straight pipe section length l = l1 + l2, and flange radius r f , flange thickness t f .

[0008] The above-mentioned pipe bending process parameters are input through the target pipe fitting parameter set and matched in the pipe bending process database to obtain pipe bending process parameters including springback compensation angle φ c , springback compensation coefficient k, bending speed v φ , boosting speed v p , boosting force F p , clamping die length l clamping , anti-wrinkle die length l foldproof , bending die radius r bending , mandrel type, mandrel material, lubrication method between dies, and pipe bending developed dimension L. Among them: is the relative pipe diameter, is the relative bending radius, φ is the target bending angle, E is Young's modulus, σ s is the yield strength, σ b is the tensile strength, is the material yield ratio, d is the outer diameter of the target pipe fitting, t is the wall thickness, r is the bending radius, and the pipe bending developed dimension L = l + (φ + kφ c )r

[0009] The above-mentioned pipe bending process database refers to the corresponding relationship database between different target pipe fitting dimensions, material properties, and corresponding optimal pipe bending process parameters. The source of the corresponding relationship data is historical data, process documents, and processing experience

[0010] The above-mentioned real-time monitoring means: periodically sampling and measuring the real-time bending angle φ of the pipe measure . When the measured real-time bending angle of the pipe reaches φ measure = φ + φ c , end the pipe bending forming process and release the fixture; then measure the final actual bending forming angle φ final after springback of the bent pipe and the actual total straight pipe section length l final .

[0011] The above-mentioned optimization method for the bending process of the welded-then-bent pipe fitting specifically includes:

[0012] Step 1: Obtain the corrected springback compensation angle φ final ' according to the difference between the final bending angle φ c and the target bending angle φ, where φ c ' = φ final + φ - φ

[0013] Step 2: Calculate the corrected springback compensation coefficient And calculate the corrected elbow expansion size L′ = l + (φ + k′φ c ′)r accordingly.

[0014] Step 3: Based on the corrected springback compensation angle φ c ′ and the elbow expansion size L′, re - implement pipe cutting and blanking, flange welding, and elbow forming until the pipe forming accuracy index reaches the design goal.

[0015] The described elbow forming accuracy index includes: bending angle error Δφ = φ - φ final and straight pipe section length error Δl = l - l final . Technical effects

[0016] The present invention automatically selects preset elbow process parameters according to the forming target of the welded - before - bent pipe fittings, and automatically iteratively optimizes the elbow process parameters based on the process parameters and the real - time monitoring data of the forming accuracy index during the elbow forming process. Compared with the prior art, the present invention significantly reduces the number of elbow reworks, and there is no need to adjust the process parameters by the way of manual repeated trial - and - error, which significantly improves the primary bending forming accuracy and production efficiency of the welded - before - bent pipe fittings. Description of the drawings

[0017] Figure 1 is the flow chart of the present invention; [[ID=3(]]

[0018] Figure 2 is the size diagram of the target elbow pipe fitting in the embodiment;

[0019] Figure 3 is the corresponding straight pipe size diagram after the elbow in the embodiment is expanded;

[0020] Figure 4 is the comparison diagram of the elbow springback angle in the embodiment and the existing elbow springback angle;

[0021] In the figure: 1 is the target elbow pipe fitting, 2 is the corresponding straight pipe after the target elbow pipe fitting is expanded, 3 is the welded - before - bent pipe fitting formed without using this method, and 4 is the welded - before - bent pipe fitting formed using this method. Detailed implementation manners

[0022] As Figure 1 shown, this embodiment designs a full - process optimization control method for the forming accuracy of welded - before - bent pipes, including:

[0023] Step 1: Determine the size of the target elbow pipe fitting and the performance of the selected material, specifically including:

[0024] 1.1 As Figure 2As shown, the dimensional parameters of the target bent pipe fitting are as follows: outer diameter d = 60 mm, wall thickness t = 4 mm, target bending angle φ = 180°, bending radius r = 350 mm, straight pipe section lengths at both ends l1 = l2 = 967 mm, total length of the straight pipe section l = 1938 mm, flange radius r f = 50 mm, flange thickness t f = 5 mm.

[0025] 1.2 The selected material is Q345 steel, and the Young's modulus E = 210 GPa, yield strength σ s = 345 MPa, tensile strength σ b = 520 MPa.

[0026] Step 2: Determine whether the target bent pipe fitting can be welded first and then bent. The dimensions of the target bent pipe fitting meet the criterion min(l1, l2) > r, so it can be welded first and then bent.

[0027] Step 3: Select a preset method through the bending process of welded-then-bent pipe fittings to obtain the bending process parameters and the developed dimensions of the bent pipe, specifically including:

[0028] 3.1 Extract the dimensions of the target bent pipe fitting, including outer diameter d = 60 mm, wall thickness t = 4 mm, target bending angle φ = 180°, and bending radius r = 350 mm.

[0029] 3.2 According to the material grade of the target bent pipe fitting, extract the corresponding material property data, including Young's modulus E = 210 GPa, yield strength σ s = 345 MPa, tensile strength σ b = 520 MPa.

[0030] 3.3 Nondimensionalize some of the pipe fitting dimensions and material property data, including relative pipe diameter relative bending radius material yield ratio Combine to form the parameter set of the target bent pipe fitting {0.0667, 5.833, 180°, 210 GPa, 0.663}.

[0031] 3.4 Using the parameter set of the target bent pipe fitting {0.0667, 5.833, 180°, 210 GPa, 0.663} as input, match in the bending process database to obtain the corresponding preset bending process parameters, where the springback compensation angle φ c = 5.46°, springback compensation coefficient k = 1, bending speed v φ = 25°, boosting speed v p = 10 mm / s, boosting force F p = 0, clamping die length l clamping= 120 mm, the length l of the anti-wrinkle die foldproof = 550 mm, the radius r of the bending die bending = 350 mm, the mandrel type is a round-head mandrel, the mandrel material is carbon steel, and the lubrication method between the dies is to apply grease.

[0032] 3.5 Calculate the developed size of the target bent pipe according to the formula The straight pipe corresponding to the developed target bent pipe is as Figure 3 shown.

[0033] Step 4: Cut a straight pipe with a corresponding length according to the selected developed size L = 3066.9 mm of the bent pipe, and weld flanges at both ends of the straight pipe.

[0034] Step 5: Input the preset bent pipe process parameters determined in Step 3 into the bent pipe machine program, start the bent pipe machine, and perform real-time springback regulation on the bending process of the pipe welded first and then bent by measurement, and monitor the real-time bending angle φ of the pipe measure , take a sample every Δt = 0.01 s until the bending angle when the pipe is not unloaded is detected to reach φ measure = φ + φ c = 185.42°, at this time, it is predicted that the bending angle φ of the pipe after unloading and springback is 180°, end the bent pipe forming process, and release the fixture; then measure the final actual bending forming angle φ of the bent pipe after springback final = 181.1° and the actual straight pipe section length l final = 1938 mm.

[0035] Step 6: Amend the bent pipe process parameters through the bending process optimization method for the pipe welded first and then bent, specifically including:

[0036] 6.1 Calculate the corrected springback compensation angle φ final according to the difference between the final bending angle φ c ′ = φ c + φ - φ final = 5.42° + 180° - 181.1° = 4.32°.

[0037] 6.2 Calculate the corrected springback compensation coefficient and calculate the corrected developed size L′ = l + (φ + k′φ c ′)r = 3059.5 mm.

[0038] Step 7: Based on the corrected springback compensation angle φ c ′ and the developed size L′ of the bent pipe, re-implement pipe cutting and blanking, flange welding, and bent pipe forming.

[0039] After specific experiments, for the tube formed by the full-process control of welding first and then bending using this method, the actual bending angle φ was measured. final = 179.96°, and the lengths of the straight pipe sections at both ends were l 1final = 966.5 mm and l 2final = 967.3 mm. There was no wrinkling or cracking. The maximum ovality was 3.82%, and the maximum outer-side thinning rate was 6.59%, meeting the process standards.

[0040] As shown in Table 1, compared with the actual bending angle φ = 177.32° of the pipe fittings made by the existing welding-first-and-then-bending process, the springback of the welding-first-and-then-bending pipe obtained by the present invention was only 0.04°, significantly improving the one-time bending forming quality of the welding-first-and-then-bending pipe fittings, reducing the number of reworks, and improving the production efficiency.

[0041] Table 1 Forming accuracy index Embodiment Existing method Bending angle 179.96° 177.32° Length of straight pipe section 1 966.5 mm 961.7 mm Length of straight pipe section 2 967.3 mm 975.9 mm Out-of-roundness 3.82％ 6.29％ Outer side thinning rate 6.59％ 10.23％

[0042] Compared with the prior art, this method significantly improves the full-process one-time forming accuracy of welding first and then bending for flanged elbows, improving the production quality and efficiency.

[0043] The above specific implementation can be locally adjusted in different ways by those skilled in the art without departing from the principles and purposes of the present invention. The protection scope of the present invention is subject to the claims and is not limited by the above specific implementation. All implementation solutions within its scope are subject to the present invention.

Claims

1. A full-process optimization control method for the forming accuracy of welded and then bent pipe materials, characterized in that, After making a process prediction based on the dimensions of the target bent pipe fitting, calculate the bending process parameters and the developed size of the bent pipe, and fabricate a straight pipe with a flange. Conduct a bending forming process for the straight pipe with a flange with real-time monitoring, measure the real-time data of the forming accuracy index of the pipe material, and iteratively optimize the bending process parameters through the bending process optimization method for the pre-welded and then-bent pipe fitting, so as to achieve the required forming accuracy index of the bent pipe while realizing the optimized control of the forming accuracy of the pre-welded and then-bent pipe material.

2. The full-process optimization control method for the forming accuracy of pre-welded and post-bent pipe materials according to claim 1, wherein The so-called process prediction means: calculating that the dimensions of the target bent pipe fitting meet or when min(l1, l2) > r, it is considered that post-welding and then bending treatment can be carried out, where: r is the bending radius, and l1 and l2 are the lengths of the straight pipe sections at both ends, that is, the total length of the straight pipe section l = l1 + l2.

3. The full-process optimization control method for the forming accuracy of pre-welded and post-bent pipe materials according to claim 1, wherein The target bend pipe dimensions include: the outer diameter d of the target bend pipe, the wall thickness t, the target bending angle φ, the bending radius r, the lengths of the straight pipe sections at both ends l1 and l2, the total length of the straight pipe section l = l1 + l2, the flange radius r f , flange thickness t f .

4. The full-process optimization control method for the forming accuracy of pre-welded and post-bent pipe materials according to claim 1, characterized in that, The described elbow pipe process parameters are input through the target elbow pipe part parameter set and matched in the elbow pipe process database to obtain the elbow pipe process parameters including the springback compensation angle φ c , springback compensation coefficient k, bending speed v φ , boosting speed v p , boosting force F p , clamping die length l clamping , anti-wrinkle die length l foldproof , bending die radius r bending , mandrel type, mandrel material, lubrication method between dies, and the elbow pipe unfolding dimension L. Among them: is the relative pipe diameter, is the relative bending radius, φ is the target bending angle, E is the Young's modulus, σ s is the yield strength, σ b is the tensile strength, is the material yield ratio, d is the outer diameter of the target elbow pipe part, t is the wall thickness, r is the bending radius, and the elbow pipe unfolding dimension L = l + (φ + kφ c )r.

5. The full-process optimization control method for the forming accuracy of pre-welded and post-bent pipe materials according to claim 1, characterized in that The so-called real-time monitoring means: periodically sampling and measuring the real-time bending angle φ of the pipe measure , when the measured real-time bending angle of the pipe reaches φ measure = φ + φ c , the pipe bending forming process is ended and the fixture is released; then measure the final actual bending forming angle φ final after the pipe bends and rebounds and the total length l of the actual straight pipe section final .

6. The full-process optimization control method for the forming accuracy of pre-welded and post-bent pipe materials according to claim 1, characterized in that The bending process optimization method for the pre-welded and then-bent pipe fitting specifically includes: Step 1: Obtain the corrected springback compensation angle φ′ according to the difference between the final bending angle φ final and the target bending angle φ c ′ = φ c + φ - φ final ; Step 2: Calculate the corrected springback compensation coefficient And calculate the corrected elbow expansion size L′ = l + (φ + k′φ c ′)r accordingly; Step 3: Based on the corrected springback compensation angle φ c ′ and the developed size L′ of the bent pipe, re-perform pipe cutting and blanking, flange welding, and bent pipe forming until the pipe forming accuracy index reaches the design target.

7. The full-process optimization control method for the forming accuracy of pre-welded and post-bent pipe materials according to claim 1, characterized in that, The described bending pipe forming accuracy indexes include: bending angle error Δφ = φ - φ final , straight pipe section length error Δl = l - l final .

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