Circular tube intersecting line machining process

Abstract

The invention discloses a circular tube intersecting line machining process, and aims to improve the cutting precision and welding quality of a circular tube intersecting line. According to the technology, parameters such as the size, the wall thickness, the intersection angle and the axis offset of a main pipe and a branch pipe are input, a mathematical model is used for calculating a theoretical curve of an intersecting line, and an accurate cutting path is generated according to the theoretical curve. The position of a to-be-cut pipe fitting is scanned in real time through the laser displacement sensor, and dynamic adjustment and compensation in the cutting process are carried out by combining theoretical and actual measurement data, so that it is ensured that the cutting precision and the welding groove angle meet the requirements. Experimental results show that cutting angle errors can be effectively controlled, the smooth surface of a groove is guaranteed, the cutting precision is high, and the strength of a welding joint is improved. The process is not only suitable for conventional pipeline connection, but also capable of treating complex intersecting geometric shapes, and has wide industrial application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of metal processing, and in particular relates to a processing technology for a circular tube intersection line. Background Art

[0002] The intersection of circular tubes is a common complex geometric shape in industrial manufacturing, and is widely used in the fields of petrochemical, construction engineering, aerospace, etc. Traditionally, the processing of intersections is mostly done by hand cutting or template cutting, which can easily lead to low processing accuracy and large groove shape errors, thus affecting the welding quality. In recent years, CNC machining and laser cutting technologies have gradually been applied to the field of intersection processing, but the current process still faces the following problems:

[0003] (1) The lack of accurate modeling of the intersection line theoretical curve and processing path optimization limits the cutting accuracy and efficiency.

[0004] (2) The cutting path cannot be corrected in real time during the processing, resulting in the difficulty in controlling the processing deviation.

[0005] (3) The process parameters of laser cutting, such as speed and energy distribution, do not fully consider the material properties and geometric shape, which affects the quality of the groove.

[0006] Therefore, there is an urgent need for a round tube intersection line processing technology that can combine CNC systems with laser cutting equipment to achieve high-precision processing through precise modeling and path optimization to meet the needs of modern industry for high-precision processing and high-quality welding. Summary of the invention

[0007] To solve the above problems, the present invention discloses a processing technology for the intersection line of a circular tube, which can establish an accurate intersection line parameter model through a numerical control system, and realize high-precision and high-quality groove processing in combination with a laser cutting device. The processing technology of the present invention includes the steps of data input, parameter calculation, path optimization, laser cutting and quality inspection, realizing the precise combination of theory and practical processing.

[0008] To achieve the above object, the technical solution of the present invention is as follows:

[0009] A circular tube intersection line processing technology comprises the following steps:

[0010] S1. Clamp the round tube to be processed by a positioner to ensure that the initial position and angle of the axis of the round tube meet the design requirements. The round tube includes a main tube and a branch tube;

[0011] S2. Input the basic parameters of the intersection line of the circular tubes in the operation interface of the CNC machining system, wherein the basic parameters of the intersection line include the main tube radius R, the branch tube radius r, the branch tube wall thickness t, the intersection angle α of the two tube axes, the offset e of the two tube axes, and the material properties;

[0012] S3. According to the input parameters, establish the equation of the branch cylindrical surface in space:

[0013] (xe) 2 +y 2 =r 2

[0014] And the equation of the main cylindrical surface:

[0015] x 2 +z 2 =R 2

[0016] By combining the above equations, eliminating the invariant and introducing the intersection angle α between the two tube axes for spatial transformation, the parametric equation of the intersection line is obtained:

[0017] x = Rcosθ;

[0018] y=e+r cosθsinα;

[0019] z = R sin θ - r cos θ cos α;

[0020] Among them, θ is the free parameter on the intersection line of the circular tube, 0≤θ≤2π;

[0021] According to the parametric equation, the three-dimensional coordinates of discrete points on the intersection line are calculated;

[0022] S4. Calculate the unit normal vector of the tangent plane of the main and branch cylindrical surfaces at each intersection point and

[0023]

[0024] The dihedral angle ψ of the two pipes to be welded is calculated by the angle between the normal vectors:

[0025]

[0026] According to the dihedral angle ψ, calculate the groove angle β:

[0027]

[0028] The laser cutting path is generated based on the angle bisector of the groove angle;

[0029] S5. Use a laser displacement sensor to scan the groove, obtain the actual geometric shape and error offset value of the groove, perform least squares fitting on the actual groove based on the scanned data, calculate the deviation value and correct the cutting path;

[0030] S6. Using the non-uniform rational B-spline curve to fit the corrected cutting path, the laser cutting equipment cuts the round tube along the optimized curve to achieve high-precision intersection line processing;

[0031] S7. Deburr and clean the groove surface after cutting, and check whether the groove angle and geometric shape meet the design requirements.

[0032] As an improvement of the present invention, in step S3, the intersection line theoretical curve is calculated by a numerical integration method, wherein the step length is Δθ=1° to ensure the calculation accuracy.

[0033] As an improvement of the present invention, in step S4, the calculation error of the groove angle is controlled within the range of ±0.1° to meet the requirements of high-precision welding.

[0034] As an improvement of the present invention, in step S6, the laser cutting speed is adjusted according to the branch pipe wall thickness t, and the range is 500-2000 mm / min.

[0035] As an improvement of the present invention, in step S7, the allowable error range of the groove angle after cutting is ±0.5°, and the cutting surface roughness is ≤6.3 μm.

[0036] The beneficial effects of the present invention are:

[0037] The present invention generates a processing path that is consistent with theory and practice by using the spatial parameter equation of the intersection line and the calculation of the dihedral angle, combined with the least squares fitting technology, with a cutting accuracy of ±0.5° and a surface roughness of ≤6.3μm. The cutting speed can be adjusted according to the wall thickness of the branch pipe, and the cutting efficiency can be optimized within the range of 500-2000mm / min. The laser displacement sensor scans the actual shape of the groove and dynamically adjusts the cutting path to ensure stable processing quality. The CNC processing system is used to reduce manual intervention and is suitable for mass production needs.

[0038] The invention solves the technical problems of low traditional processing precision, low efficiency and unstable quality, and is suitable for processing the intersection lines of round tubes of various materials and specifications. DETAILED DESCRIPTION

[0039] The present invention will be further explained below in conjunction with specific implementation modes. It should be understood that the following specific implementation modes are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0040] Example 1

[0041] S1. Material preparation

[0042] (1) Main pipe: outer diameter 200mm, wall thickness 10mm, material is Q235 steel;

[0043] (2) Branch pipe: outer diameter 100 mm, wall thickness 8 mm, material is Q235 steel;

[0044] (3) Intersection parameters: The intersection angle between the two tube axes is 90°, and the offset between the two tube axes is 0 mm.

[0045] S2. Parameter input

[0046] Main pipe radius R = 100mm;

[0047] Branch pipe radius r = 50 mm;

[0048] Branch pipe wall thickness t = 8mm;

[0049] The intersection angle of the two tube axes α = 90°;

[0050] The offset between the two pipe axes is e = 0 mm;

[0051] Material properties: Q235 steel, cutting speed range 500-2000mm / min.

[0052] S3. Establish the intersection line theoretical curve

[0053] The parametric equation of the intersection line is established using the above input parameters:

[0054] x = 100 cosθ;

[0055] y = 50cosθ;

[0056] z = 100 sinθ - 50 cosθ;

[0057] According to the step size Δθ=1°, the three-dimensional coordinates of the discrete points are calculated (part of the calculation results are shown in Table 1).

[0058] Table 1 Three-dimensional coordinates of discrete points on the intersection line

[0059]

[0060]

[0061] S4. Groove Angle Calculation

[0062] Calculate the groove angle β based on the coordinates of the discrete points

[0063] (1) Calculate the unit normal vector of the tangent plane of the main and branch cylindrical surfaces and

[0064]

[0065] (2) Calculate the dihedral angle ψ of the two pipes to be welded:

[0066]

[0067] (3) Calculate the groove angle β:

[0068]

[0069] Some calculation results are shown in Table 2.

[0070] Table 2 Calculation results of groove angle

[0071] θ(°) ψ(°) β(°) 0 45 67.5 45 30 75 90 90 45

[0072] S5. Cutting Experiment

[0073] (1) Cutting equipment: three-axis laser cutting machine, light source power 3kW;

[0074] (2) Cutting speed: According to the wall thickness t of the branch pipe, select 1200 mm / min;

[0075] (3) Cutting path: Non-uniform rational B-spline (NURBS) is used to fit discrete points and optimize the cutting trajectory.

[0076] S6. Result detection

[0077] Groove surface roughness = 5.5μm; cutting angle error is controlled within ±0.3°;

[0078] Welding experiments show that the groove angle matches the actual welding effect well, and there are no obvious weld defects.

[0079] Example 2

[0080] (1) Based on Example 1, the sizes and parameters of the main pipe and branch pipe are changed as follows:

[0081] The outer diameter of the main pipe is 300mm and the wall thickness is 15mm; the outer diameter of the branch pipe is 150mm and the wall thickness is 10mm; the intersection angle of the two pipe axes is 60°, and the offset of the two pipe axes is 20mm.

[0082] (2) Experimental results

[0083] The step size of the discrete points for generating the intersection line is Δθ = 0.5° to improve the fitting accuracy of complex geometry;

[0084] Groove surface roughness = 6.1μm, cutting angle error is controlled within ±0.4°;

[0085] After actual welding test, the welding strength reached 1.2 times of the design value.

[0086] In summary, through the experimental results of Example 1 and Example 2, the following data analysis conclusions can be drawn:

[0087] First, in Example 1, by reasonably selecting cutting parameters (such as cutting speed and light source power) and calculating the groove angle according to the pipe diameter, wall thickness and intersection angle, the high precision of the cutting path and the welding quality are ensured. Under this condition, the surface roughness of the groove is controlled at 5.5 μm, and the cutting angle error is less than ±0.3°, which shows that this method can effectively ensure the accuracy of the intersection line of the pipe before welding, thereby reducing the defects that may occur during the welding process and ensuring the strength and stability of the welded joint.

[0088] Example 2 further demonstrates the adaptability of this method under different sizes and complex geometric conditions. In this experiment, the size of the main and branch pipes and the intersection angle were changed, and the axis offset of the pipe fittings was increased. Despite the large changes in conditions, the groove angle calculation still maintained a high degree of accuracy. The final welding results showed that the groove surface roughness reached 6.1μm, the cutting angle error was controlled within ±0.4°, and the joint strength after welding was increased by 1.2 times, indicating that under different working conditions, this method can still stably provide high-quality cutting and welding effects.

[0089] It can be seen from the results of Example 1 and Example 2 that the cutting path optimization based on the intersection line can not only effectively control the cutting accuracy and welding quality, but also has strong adaptability and reliability in practical applications. The optimized calculation model and cutting method have good processing effects on pipes with complex geometric shapes, and can effectively improve the quality of welded joints and reduce welding defects. This provides an efficient and accurate solution for pipeline welding in the industrial field.

[0090] It should be noted that the specific implementation methods only illustrate the technical ideas of the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.

Claims

1. A process for processing a circular tube intersection line, characterized in that: The following steps are involved: S1. Clamp the round tube to be processed by a positioner to ensure that the initial position and angle of the axis of the round tube meet the design requirements. The round tube includes a main tube and a branch tube; S2. Input the basic parameters of the intersection line of the circular tubes in the operation interface of the CNC machining system, wherein the basic parameters of the intersection line include the main tube radius R, the branch tube radius r, the branch tube wall thickness t, the intersection angle α of the two tube axes, the offset e of the two tube axes, and the material properties; S3. According to the input parameters, establish the equation of the branch cylindrical surface in space: (x-e) 2 +y 2 =r 2 And the equation of the main cylindrical surface: x 2 +z 2 =R 2 By combining the above equations, eliminating the invariant and introducing the intersection angle α between the two tube axes for spatial transformation, the parametric equation of the intersection line is obtained: x = Rcosθ; y = e + rcosθsinα; z = R sin θ - rcos θ cos α; Among them, θ is the free parameter on the intersection line of the circular tube, 0≤θ≤2π; According to the parametric equation, the three-dimensional coordinates of discrete points on the intersection line are calculated; S4. Calculate the unit normal vector of the tangent plane of the main and branch cylindrical surfaces at each intersection point and The dihedral angle ψ of the two pipes to be welded is calculated by the angle between the normal vectors: According to the dihedral angle ψ, calculate the groove angle β: The laser cutting path is generated based on the angle bisector of the groove angle; S5. Use a laser displacement sensor to scan the groove, obtain the actual geometric shape and error offset value of the groove, perform least squares fitting on the actual groove based on the scanned data, calculate the deviation value and correct the cutting path; S6. Using the non-uniform rational B-spline curve to fit the corrected cutting path, the laser cutting equipment cuts the round tube along the optimized curve to achieve high-precision intersection line processing; S7. Deburr and clean the groove surface after cutting, and check whether the groove angle and geometric shape meet the design requirements.

2. The process for processing the intersecting line of a circular tube according to claim 1, characterized in that: In step S3, the intersection line theoretical curve is calculated by a numerical integration method, wherein the step length is Δθ=1° to ensure the calculation accuracy.

3. The process for processing the intersecting line of a circular tube according to claim 1, characterized in that: In step S4, the calculation error of the groove angle is controlled within the range of ±0.1° to meet the requirements of high-precision welding.

4. The process for processing the intersecting line of a circular tube according to claim 1, characterized in that: In step S6, the laser cutting speed is adjusted according to the wall thickness t of the branch pipe, and the range is 500-2000 mm / min.

5. The process for processing the intersecting line of a circular tube according to claim 1, characterized in that: In the step S7, the tolerance range of the groove angle after cutting is ±0.5°, and the cutting surface roughness is ≤6.3 μm.

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