A welding process and apparatus for polygonal tower sections and cylinders

Abstract

The application discloses a welding process and device for a polygonal tower drum and a cylinder, and the process comprises the following steps: placing the tower drum on an inclined tool, adjusting the inclination angle of the tool, making the center of gravity of the tower drum close to the inner side of the tool, and arranging rollers below adjacent cylinder tower segments; adjusting the welding groove according to the inclination angle, adopting an asymmetric groove form with 1 / 2-2 / 3 of the outer side and 1 / 3-1 / 2 of the inner side; performing outer ring seam welding in the inclined state, performing carbon planing cleaning on the root of the inner side weld after welding; and performing inner side ring seam welding after the carbon planing cleaning is completed. The device comprises an inclined tool and a reinforcing ring plate, the inclined tool is provided with an angle adjusting mechanism and a roller mounting position, and the reinforcing ring plate is attached to the side of the cylinder tower segment. The application utilizes the directional flow of the molten pool guided by gravity through the inclined tool and the welding process, cooperates with the asymmetric groove and local grinding at the edge, solves the problems of incomplete fusion, poor forming and tilting risk in the ring seam welding of the polygonal tower drum and the cylinder, and thus improves the welding quality and efficiency.

Description

Technical Field

[0001] This invention relates to the field of wind tower manufacturing technology, specifically to a welding process and apparatus for polygonal tower cylinders and cylindrical cylinders. Background Technology

[0002] As a key structure supporting wind turbine units, the manufacturing quality of wind turbine towers directly affects the operational safety and stability of the wind turbines. With the diversification of wind turbine tower structures, combined structures of polygonal and cylindrical tower sections are increasingly being used in practical engineering. However, the circumferential welding of these irregularly shaped tower sections faces numerous technical challenges.

[0003] In the Tianyuan Difang wind tower project, the bottom section is a 24-sided tower section, which requires circumferential welding with the adjacent cylindrical tower section. Preliminary trial welding verification showed that when using the traditional horizontal roller welding method, the irregularity of the polygonal structure caused the tower to climb during rotation, leading to frequent adjustments of the welding machine head, unstable wire feeding, and welding defects such as arc deviation, incomplete fusion, and slag inclusions. Simultaneously, the weld formation quality was poor, especially in the sharp corner areas where there was a significant alternation between uphill and downhill welding, resulting in severe weld protrusion and increased grinding workload. Furthermore, the small contact area between the polygonal tower section and the rollers posed a risk of vertical jumping and lateral tilting of the tower during welding, seriously affecting welding quality and operational safety.

[0004] In summary, existing welding processes are insufficient to meet the high-quality and high-efficiency welding requirements of polygonal tower sections and cylindrical tower sections. There is an urgent need for a welding process and device that is structurally stable, easy to operate, and produces excellent results. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings shown in the background art.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows.

[0007] In a first aspect, this disclosure provides a welding process for a polygonal tower and a cylindrical tube, comprising the following steps: S1. Place the tower on the inclined fixture, adjust the inclination angle of the fixture so that the center of gravity of the tower is close to the inside of the fixture, and place the rollers below the adjacent cylindrical tower sections. S2. Adjust the welding bevel according to the tilt angle, and adopt an asymmetrical bevel form in which the outer side occupies 1 / 2 to 2 / 3 and the inner side occupies 1 / 3 to 1 / 2; S3. Perform outer circumferential weld in an inclined state, and clean the root of the inner weld with carbon gouging after welding. S4. After the carbon planing cleaning is completed, perform inner circumferential welding.

[0008] As a preferred technical solution, in S1, the polygonal tower is placed on an inclined fixture, the circumferential phase of the tower is adjusted so that its edges avoid the area directly above the roller support point, and then the inclination angle of the fixture is adjusted to 15~30 degrees so that the center of gravity of the tower is close to the inside of the fixture.

[0009] As a preferred technical solution, the processing method of the bevel in S2 is as follows: firstly, a continuous outer bevel surface is processed along the circumference of the tower on the outside, and then the bevel is locally ground at each edge of the polygonal tower so that the outer bevel angle within a range of 20~50mm on both sides of the edge is reduced by 2~5 degrees.

[0010] As a preferred technical solution, after the beveling process described in S2 is completed, the beveling depth is measured along the circumference of the tower, and abnormal depth points are marked at the edges of the polygonal tower. The beveling depth deviation of the entire circle is controlled within ±2mm by local welding and grinding.

[0011] As a preferred technical solution, the beveling process described in S2 and the adjustment of the tilt angle described in S1 have the following coordination relationship: The tilt angle θ set in S1 determines the flow direction of the molten pool metal under the action of gravity during welding. The theoretical angle β between the welding wire axis and the beveling sidewall is calculated based on θ, and then the theoretical value α of the outer beveling angle is determined, where α and β are complementary. First, an initial beveling with an outer beveling angle of α is processed. The tower is placed on the tilting fixture and rotated one revolution at the welding speed. The contact marks between the welding wire and the two sidewalls of the beveling are observed. If the marks are biased towards the outer sidewall of the beveling, the beveling angle is reduced by 1 to 2 degrees. If the marks are biased towards the inner sidewall, the beveling angle is increased by 1 to 2 degrees. The above observation and correction steps are repeated until the welding wire marks are located within the same width range on both sides of the beveling centerline.

[0012] As a preferred technical solution, the outer circumferential seam welding in S3 adopts a symmetrical arrangement of two welding guns. The two welding guns are 180 degrees apart along the circumference of the tower and both move from the high position to the low position. The welding current of the two welding guns differs by 10% to 15%.

[0013] As a preferred technical solution, after the first layer of weld bead of the outer circumferential seam weld described in S3 is completed, the welding is paused, the tower is rotated 180 degrees in the opposite direction, and then the second layer of weld bead is welded from the high position to the low position in the opposite direction, so that the fusion direction of the adjacent weld bead intersects with each other.

[0014] As a preferred technical solution, during the outer circumferential seam welding described in S3, the welder uses the arc-striking welding method to briefly extinguish the arc 20-30mm before each polygonal edge enters the welding area. After the vertex of the edge passes directly below the welding gun, the arc is reignited. By controlling the arc interruption time, the molten pool metal forms a continuous transition on both sides of the edge.

[0015] As a preferred technical solution, the carbon planing cleaning described in S3 includes the following steps: After the outer circumferential weld is completed, carbon planing is performed at the root of the inner weld along the circumference of the tower. During carbon planing, the arc is started from the midpoint of each edge of the polygonal tower and the planing extends to both sides of the edge, forming a V-shaped groove extending from the midpoint to both sides at each edge, so that the grooves between adjacent edges meet in the middle of the straight edge section.

[0016] Secondly, this disclosure provides a welding device including a polygonal tower section and a cylindrical section, comprising an inclined fixture and a reinforcing ring plate; the inclined fixture includes a base, an inclined support structure and an angle adjustment mechanism, the inclined support structure is connected to the base, and the angle adjustment mechanism is used to adjust the inclination angle of the inclined support structure; the inclined support structure is provided with a roller mounting position; the reinforcing ring plate is a conformal structure adapted to the cylindrical section and fits against the side of the cylindrical tower section.

[0017] The advantages and beneficial effects of this invention are as follows: By using inclined tooling and welding process, the tower's center of gravity is first shifted inward using a 15-30 degree inclined tooling. Combined with rollers arranged in adjacent cylindrical segments, the molten pool metal is guided by gravity to flow directionally from a high position to a low position, naturally transforming the weld formation from the "convex" shape of traditional horizontal welding to the "concave" shape required by the drawing, reducing grinding workload. Based on the inclined angle, the bevel is designed asymmetrically and locally ground, ensuring the welding wire axis is always located in the center area of ​​the bevel, avoiding incomplete fusion defects caused by arc deviation. By setting local bevel angle reductions and depth deviation control at the edges, uniform filling of the molten metal in the polygonal sharp corner areas is achieved, solving the problem of abrupt forming changes caused by concentrated heat input at the sharp corners. Furthermore, in the carbon planing cleaning process, a symmetrical planing path extending from the midpoint of the edge to both sides is used, forming a V-shaped stress relief groove at each edge. This allows the planing grooves of adjacent straight edge segments to naturally converge, releasing residual stress caused by abrupt changes in the cross-section of the polygonal structure and reducing shrinkage deformation during subsequent welding.

[0018] Application verification shows that this invention significantly improves the first-pass yield of welds and reduces operational difficulty and rework costs. Attached Figure Description

[0019] Figure 1 This is one of the structural schematic diagrams of the device shown in this invention.

[0020] Figure 2 This is the second schematic diagram of the device shown in this invention.

[0021] Figure 3 This is the third schematic diagram of the device shown in this invention.

[0022] Figure 4 This is one of the schematic diagrams of beveling shown in this invention.

[0023] Figure 5 This is the second schematic diagram of the beveling process shown in this invention.

[0024] Figure 6 This is a schematic diagram of the V-shaped groove for carbon polishing as shown in this invention.

[0025] Figure label: 1-Base, 2-Inclined support structure, 3-Angle adjustment mechanism, 4-Roller mounting position, 5-Reinforcing ring plate. Detailed Implementation

[0026] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0027] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] This invention provides a welding process and apparatus for polygonal tower sections and cylindrical sections, applicable to the field of wind turbine manufacturing technology, particularly for the circumferential welding of the bottom 24-sided tower section and adjacent cylindrical tower section in wind turbine projects with a circular base. It solves the risks of incomplete fusion, poor forming, and lateral tilting in the circumferential welding of polygonal tower sections and cylindrical sections, thereby improving welding quality and efficiency.

[0030] The welding process between the polygonal tower and the cylindrical section provided by this invention includes the following steps: S1, placing the tower on an inclined fixture, adjusting the inclination angle of the fixture so that the center of gravity of the tower is close to the inner side of the fixture, and arranging the rollers below the adjacent cylindrical tower sections; S2, adjusting the welding bevel according to the inclination angle, adopting an asymmetrical bevel form with the outer side occupying 1 / 2 to 2 / 3 and the inner side occupying 1 / 3 to 1 / 2; S3, performing outer circumferential welding in an inclined state, and cleaning the root of the inner weld with carbon gouging after welding; S4, performing inner circumferential welding after carbon gouging.

[0031] In step S1, the tower is adjusted from a traditional horizontal placement to an inclined placement. When the polygonal tower is rotated for welding in a horizontal state, the contact point between the roller and the tower changes periodically with rotation because the polygonal cross-section is composed of multiple planes and edges. This causes the center of gravity of the tower to shift in the vertical plane. This fluctuation in the center of gravity causes the relative position of the welding torch and the bevel to change continuously, and the wire extension length to fluctuate accordingly. This disrupts the arc stability and ultimately leads to defects such as arc deviation and incomplete fusion.

[0032] This invention tilts the tower at 15-30 degrees, shifting the tower's center of gravity inward toward the tooling. Roller support points are positioned below adjacent cylindrical tower sections, utilizing the regular circular cross-section of the cylindrical sections to provide stable rolling support. In the tilted state, the tower's gravity can be decomposed into a component perpendicular to the tooling support surface and a component parallel to the tooling support surface. The vertical component is borne by the rollers, while the parallel component causes the tower to tend to conform inward toward the tooling, suppressing radial runout. In the tilted state, the molten pool metal, under the influence of gravity, flows directionally from a higher to a lower position, naturally transforming the weld formation from the convex shape of traditional horizontal welding to the concave shape required by the drawing, reducing grinding workload.

[0033] It should be noted that the 15-30 degree tilt range is the optimal range obtained through a large number of experiments: when the tilt angle is less than 15 degrees, the gravity component is insufficient to guide the molten pool to spread fully, and the weld still shows obvious convex characteristics; when the tilt angle is greater than 30 degrees, the molten pool metal flows downward excessively, which may lead to weld undercut or weld beads. At the same time, the self-weight component of the tower is too large, which increases the load on the tooling and the driving torque.

[0034] In step S2, the welding bevel is adjusted according to the tilt angle, adopting an asymmetrical bevel configuration where the outer side occupies 1 / 2 to 2 / 3 of the wall thickness and the inner side occupies 1 / 3 to 1 / 2 of the wall thickness. This adjustment has profound implications in welding metallurgy. In the tilted state, the welding wire axis remains perpendicular to the direction of gravity, but the angle relative to the bevel sidewall changes with the tilt angle. If the bevel angle is not adjusted, the welding wire may deviate from the bevel center, causing the arc to be biased towards one side of the bevel wall, resulting in incomplete fusion or undercut.

[0035] This invention calculates the theoretical angle β between the welding wire axis and the bevel sidewall based on the tilt angle θ, and then determines the theoretical value α of the outer bevel angle, where α and β are complementary, ensuring that the projection of the welding wire axis in the direction of gravity is always located in the central region of the bevel gap. From the perspective of molten pool fluid dynamics, the asymmetric bevel design matches the gravitational field under tilted conditions: the outer bevel has a larger proportion, providing sufficient filling space for molten pool metal flowing from the high position to the low position; the inner bevel has a smaller proportion, reducing the amount of filling during inner welding and dispersing the shrinkage stress of the inner weld. If the outer bevel proportion is too low, the molten pool metal will overflow the bevel; if the proportion is too high, the filling amount will increase and efficiency will decrease. If the inner bevel proportion is too low, the root will not penetrate; if the proportion is too high, the inner welding difficulty will increase.

[0036] In step S3, the outer circumferential weld is performed in an inclined state, with the welding torch moving from a high position to a low position. As the welding torch moves from a high position to a low position, the molten pool metal is always supported by the solidified weld metal behind the arc, avoiding incomplete fusion and slag inclusions caused by the molten pool metal flowing forward under gravity when welding from a low position to a high position. When welding from a high position to a low position, the distribution of arc heat within the bevel is consistent with the direction of gravity-driven molten pool flow, which is beneficial for heat transfer to the root of the bevel and promotes root fusion.

[0037] After the outer circumferential weld is completed, the root of the inner weld is cleaned with carbon gouging. Carbon gouging is not only a conventional method for removing root defects, but also has a special stress control function in this invention. During the outer circumferential weld, due to the abrupt change in cross-section at the polygonal edges, the concentrated heat input leads to an increase in local thermal stress. If the inner weld is performed directly, these residual stresses may cause new welding deformations or cracks.

[0038] In step S4, after carbon gouging, the inner circumferential weld is performed. During inner welding, since the outer weld has formed a rigid constraint, the shrinkage of the inner weld is limited, which is conducive to forming a compressive stress state and improving the fatigue resistance of the weld. At the same time, the flow of the molten pool during inner welding is still guided by gravity, moving from a high position to a low position, ensuring the forming quality of the inner weld.

[0039] In some embodiments, to further suppress radial runout caused by abrupt changes in cross-section at the edges of the polygonal tower, in step S1, when placing the polygonal tower on the inclined fixture, the circumferential phase of the tower is first adjusted so that its edges avoid the area directly above the roller support point. Then, the inclination angle of the fixture is adjusted to 15-30 degrees. The edges of the polygonal tower, especially the turning points, are where the cross-section changes most drastically. When the edges pass the roller support point, the contact between the roller and the tower instantly changes from planar contact to line contact. This abrupt change in contact stiffness causes the tower to generate vertical acceleration, manifesting as a runout phenomenon. By adjusting the circumferential phase to ensure that the circumferential angle between the edges and the roller support point is greater than 30 degrees, it is ensured that the support point remains in the adjacent planar area when the edges pass the roller, resulting in a gradual change in contact stiffness and a reduced runout amplitude.

[0040] In some embodiments, to address the problem of turbulent molten pool flow caused by abrupt geometric changes in the bevel at the polygonal edges, the bevel processing method described in S2 is as follows: first, a continuous outer bevel surface is machined along the circumference of the tower cylinder on the outer side; then, the bevel is locally ground at each edge of the polygonal tower cylinder, reducing the outer bevel angle by 2-5 degrees within a 20-50mm range on both sides of the edge. From a geometric perspective, the edge of a polygon is the intersection of two planes, and conventional bevel processing will produce a geometrical abrupt change at this point, manifested as a local increase or decrease in the bevel angle. This abrupt change causes the flow path of the molten pool metal at the edge to deflect during welding, easily resulting in undercut or protrusions. This invention, by locally grinding the outer bevel angle by 2-5 degrees within a 20-50mm range on both sides of the edge, essentially creates a buffer transition zone at the edge. This transition zone guides the molten pool metal as it flows through the edge, with the gradually changing bevel sidewalls ensuring a smooth flow path. The preferred grinding range is 20-50 mm. If the range is too small, it cannot cover the complete path of the molten pool flowing through the edge; if the range is too large, it will disrupt the bevel uniformity of the straight edge section.

[0041] In some embodiments, after the beveling process described in S2 is completed, the beveling depth is measured along the circumference of the tower. Depth anomalies are marked at the edges of the polygonal tower. Local repair welding and grinding are used to control the overall beveling depth deviation within ±2mm. From the perspective of welding thermal processes, the beveling depth directly determines the amount of filler metal. Excessive depth deviation can lead to overfilling or underfilling in local areas, resulting in uneven fill height or undercut. This invention precisely corrects depth anomalies through local repair welding and grinding, controlling the overall beveling depth deviation within ±2mm, thus providing uniform geometric boundary conditions for subsequent welding.

[0042] In some embodiments, in order to achieve the optimal match between the bevel angle and the tilt posture, the bevel processing described in S2 and the tilt angle adjustment described in S1 have the following coordination relationship: The tilt angle θ set in S1 determines the flow direction of the molten pool metal under the action of gravity during welding. The theoretical angle β between the welding wire axis and the bevel sidewall is calculated based on θ, and then the theoretical value α of the outer bevel angle is determined, where α and β are complementary. First, an initial bevel with an outer bevel angle of α is processed. The tower is placed on the tilting fixture and rotated one revolution at the welding speed. The contact marks between the welding wire and the two sidewalls of the bevel are observed. If the marks are biased towards the outer sidewall of the bevel, the bevel angle is reduced by 1 to 2 degrees. If the marks are biased towards the inner sidewall, the bevel angle is increased by 1 to 2 degrees. The above observation and correction steps are repeated until the welding wire marks are located within the same width range on both sides of the bevel centerline.

[0043] In some embodiments, to improve welding efficiency and balance heat input distribution, the outer circumferential weld described in S3 employs a symmetrical arrangement of two welding torches. The two torches are 180 degrees apart along the circumference of the tower and both move from a higher to a lower position. The welding current of the two torches differs by 10% to 15%. From a thermodynamic perspective, the symmetrical arrangement of the two torches ensures a symmetrical heat distribution around the tower, reducing overall thermal deformation of the tower. When the current difference between the two torches is 10% to 15%, when the first torch welds, the molten metal fills the bevel and releases some heat; when the second torch welds at the 180-degree angle, the base material at that location has already been preheated by the heat conduction from the first torch, but the preheating is insufficient to reach the melting temperature. By setting a 10% to 15% current difference, the heat input of the second torch is slightly higher than that of the first, compensating for the loss of preheating heat and ensuring consistent weld penetration and formation at both locations.

[0044] In some embodiments, to further optimize weld formation quality, after the first weld pass of the outer circumferential weld described in S3 is completed, welding is paused, the tower is rotated 180 degrees in the opposite direction, and then the second weld pass is welded from the high position to the low position in the opposite direction, so that the fusion directions of adjacent weld passes intersect each other. From a materials science perspective, the welding fusion direction determines the grain growth orientation of the weld metal. When welding in a single direction, the grains grow along the welding direction to form columnar crystals, and the weak surfaces between the columnar crystals easily become crack propagation paths. This invention, by rotating in the opposite direction, makes the fusion directions of adjacent weld passes intersect each other, and the grain growth directions are thus staggered, forming a grain structure similar to "weaving," which effectively inhibits the propagation of intergranular cracks. At the same time, the reverse welding allows the heat of the subsequent weld to have a "tempering" effect on the previous weld, refining the grains and improving the toughness of the weld metal.

[0045] In some embodiments, to actively control the heat input at the edges of the polygonal weld, during the outer circumferential weld described in S3, the welder briefly extinguishes the arc 20-30mm before each polygonal edge enters the welding area using a flicking arc welding method. The arc is then reignited after the edge vertex passes directly below the welding torch. By controlling the arc interruption time, the molten pool metal forms a continuous transition on both sides of the edge. The cross-section at the polygonal edge changes abruptly, resulting in a smaller heat capacity and a faster temperature rise under the same heat input, easily leading to overheating or even burn-through. Traditional methods reduce heat input by decreasing the welding current, but this leads to insufficient penetration. This invention employs a flicking-extinguishing-reignition technique, actively controlling the time distribution of heat input through arc interruption. During the brief period of arc interruption, the already formed molten pool metal naturally spreads under gravity, while heat is conducted deeper into the base material, making the temperature gradient at the edge more gradual. After the edge passes, the arc is reignited, and the molten pool continues to fill on the already spread surface, avoiding overheating and ensuring penetration.

[0046] In some embodiments, the carbon planing cleaning described in S3 includes the following steps: After the outer circumferential weld is completed, carbon planing is performed at the root of the inner weld along the circumference of the tower. During carbon planing, an arc is started from the midpoint of each edge of the polygonal tower, and planing extends to both sides of that edge, forming a V-shaped groove extending from the midpoint to both sides at each edge, so that the grooves between adjacent edges meet at the middle of the straight edge section. This carbon planing path design has profound implications for fracture mechanics. The edges of the polygonal tower are geometric discontinuities where the cross-section changes abruptly, and are also natural concentration areas of residual stress.

[0047] Traditional carbon planers continuously plan a circle from any point, producing a uniform groove shape, but failing to specifically release concentrated stress at the edges. This invention employs a symmetrical planing path extending from the midpoint of the edge outwards, forming a V-shaped groove at each edge, with its tip pointing towards the edge vertex and gradually deepening towards the straight edge. From a stress field perspective, the geometry of the V-shaped groove matches the stress distribution at the edge: the stress is highest at the edge vertex, corresponding to the groove tip; the stress gradually decreases along the edges, corresponding to the gradual increase in groove depth. When the grooves of adjacent edges converge at the middle of the straight edge, the entire circle of grooves forms a continuous "wave-shaped" trajectory, allowing residual stress to be released uniformly circumferentially, avoiding new stress concentrations that might occur with traditional continuous planing.

[0048] The present invention also provides a welding device for a polygonal tower section and a cylindrical section, including an inclined fixture and a reinforcing ring plate 5; the inclined fixture includes a base 1, an inclined support structure 2 and an angle adjustment mechanism 3, the inclined support structure 2 is connected to the base 1, and the angle adjustment mechanism 3 is used to adjust the inclination angle of the inclined support structure 2; the inclined support structure 2 is provided with a roller mounting position 4; the reinforcing ring plate 5 is a conformal structure adapted to the cylindrical section and fits against the side of the cylindrical tower section.

[0049] In some embodiments, the tilting support structure 2 is a support column, and the angle adjustment mechanism 3 is a hinge point hinged to the base. The tilting support structure 2 is tilted around the hinge point by a hydraulic cylinder to perform actions such as flipping.

[0050] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0051] Example 1 This embodiment provides a welding process for a polygonal tower section and a cylindrical section, applied to a wind turbine tower project. The bottom section of the tower is 24-sided and is circumferentially welded to the adjacent cylindrical tower section. The steps are as follows: S1. Place the 24-sided tower on the inclined fixture, adjust the circumferential phase of the tower so that the circumferential angle between the quadrilateral edge and the roller support point is greater than 30 degrees, then adjust the inclination angle of the fixture to 22.5 degrees so that the center of gravity of the tower is close to the inside of the fixture, and place the roller below the adjacent cylindrical tower section. S2. Adjust the welding bevel according to the 22.5-degree tilt angle, adopting an asymmetrical bevel form with the outer side occupying 2 / 3 of the wall thickness and the inner side occupying 1 / 3 of the wall thickness. The outer bevel angle is 30 degrees, the inner bevel angle is 45 degrees, and the blunt edge dimension is 3mm. Locally grind the bevel at each edge of the tower to reduce the outer bevel angle by 3 degrees within a 30mm range on both sides of the edge. S3. Perform outer circumferential welding at an inclination of 22.5 degrees. The welding torch moves from a high position to a low position. The two welding torches are arranged symmetrically with a distance of 180 degrees between them along the circumference of the tower. The welding currents are 180A and 200A respectively, with a difference of 11%. 25mm before each edge enters the welding area, the welder uses the arc-striking welding method to extinguish the arc briefly. After the vertex of the edge passes directly under the welding torch, the arc is reignited. S4. After the outer circumferential weld is completed, the root of the inner weld is cleaned by carbon planing. When carbon planing, start from the midpoint of each edge and extend the planing to both sides to form a V-shaped groove extending from the midpoint to both sides at each edge. The groove is 4mm deep and 10mm wide, so that the grooves between adjacent edges meet in the middle of the straight edge section. S5. After carbon planing is completed, the inner circumferential seam is welded. The first layer of weld fills the planing groove, and subsequent welds are stacked layer by layer until they are flush with the base material.

[0052] According to the flaw detection test, the first pass rate of the circumferential weld in this embodiment reached 98.5%. The weld formation conformed to the concave shape required by the drawing and there were no defects such as incomplete fusion or slag inclusion. Compared with the traditional process, the grinding workload was reduced by about 70%.

[0053] Example 2 This embodiment provides a welding process for a polygonal tower and a cylindrical tube, the steps of which are as follows: S1. Place the 24-sided tower on the inclined fixture, adjust the circumferential phase of the tower so that the circumferential angle between the quadrilateral edge and the roller support point is greater than 30 degrees, then adjust the inclination angle of the fixture to 15 degrees so that the center of gravity of the tower is close to the inner side of the fixture, and place the roller below the adjacent cylindrical tower section. S2. Adjust the welding bevel according to the 15-degree tilt angle, adopting an asymmetrical bevel form with the outer side occupying 1 / 2 of the wall thickness and the inner side occupying 1 / 2 of the wall thickness. The outer bevel angle is 25 degrees, the inner bevel angle is 50 degrees, and the blunt edge dimension is 4mm. Locally grind the bevel at each edge of the tower to reduce the outer bevel angle by 2 degrees within a range of 20mm on both sides of the edge. S3. Perform outer circumferential welding at a 15-degree angle. The welding torch moves from a high position to a low position. Use a single welding torch and a welding current of 190A. 20mm before each edge enters the welding area, the welder uses the arc-striking method to extinguish the arc briefly. Re-ignite the arc after the edge vertex passes directly below the welding torch. S4. After the outer circumferential weld is completed, the root of the inner weld is cleaned by carbon planing. When carbon planing, start from the midpoint of each edge and extend the planing to both sides to form a V-shaped groove extending from the midpoint to both sides at each edge. The groove is 3mm deep and 8mm wide, so that the grooves between adjacent edges meet in the middle of the straight edge section. S5. After carbon planing is completed, the inner circumferential seam is welded. The first layer of weld fills the planing groove, and subsequent welds are stacked layer by layer until they are flush with the base material.

[0054] According to the flaw detection test, the first pass rate of the circumferential weld in this embodiment reached 96.2%. The weld formation basically met the concave shape requirements. There were slight fluctuations in the excess height at some edges. After a small amount of grinding, the requirements were met.

[0055] Example 3 This embodiment provides a welding process for a polygonal tower and a cylindrical tube, the steps of which are as follows: S1. Place the 24-sided tower on the inclined fixture, adjust the circumferential phase of the tower so that the circumferential angle between the quadrilateral edge and the roller support point is greater than 30 degrees, then adjust the inclination angle of the fixture to 30 degrees so that the center of gravity of the tower is close to the inner side of the fixture, and place the roller below the adjacent cylindrical tower section. S2. Adjust the welding bevel according to the 30-degree tilt angle, adopting an asymmetrical bevel form with the outer side occupying 2 / 3 of the wall thickness and the inner side occupying 1 / 3 of the wall thickness. The outer bevel angle is 35 degrees, the inner bevel angle is 40 degrees, and the blunt edge dimension is 2mm. Locally grind the bevel at each edge of the tower to reduce the outer bevel angle by 5 degrees within a 50mm range on both sides of the edge. S3. Perform outer circumferential welding at a 30-degree incline. The welding torch moves from a high position to a low position. The two welding torches are arranged symmetrically with a distance of 180 degrees between them along the circumference of the tower. The welding currents are 170A and 195A respectively, with a difference of 14.7%. 30mm before each edge enters the welding area, the welder uses the arc-striking welding method to extinguish the arc briefly. The arc is re-ignited after the vertex of the edge passes directly below the welding torch. S4. After the outer circumferential weld is completed, the root of the inner weld is cleaned by carbon planing. When carbon planing, start from the midpoint of each edge and extend the planing to both sides to form a V-shaped groove extending from the midpoint to both sides at each edge. The groove is 5mm deep and 12mm wide, so that the grooves between adjacent edges meet in the middle of the straight edge section. S5. After carbon planing is completed, the inner circumferential seam is welded. The first layer of weld fills the planing groove, and subsequent welds are stacked layer by layer until they are flush with the base material.

[0056] According to the flaw detection test, the first pass rate of the welded circumferential seam in this embodiment reached 97.8%, the weld formation met the concave shape requirements, and there were slight undercuts at some edges, which met the requirements after repair welding.

[0057] Example 4 This embodiment provides a welding process for a polygonal tower and a cylindrical tube, the steps of which are as follows: S1. Place the 24-sided tower on the inclined fixture, adjust the circumferential phase of the tower so that the circumferential angle between the quadrilateral edge and the roller support point is greater than 30 degrees, then adjust the inclination angle of the fixture to 22.5 degrees so that the center of gravity of the tower is close to the inside of the fixture, and place the roller below the adjacent cylindrical tower section. S2. Adjust the welding bevel according to the 22.5-degree tilt angle, adopt an asymmetrical bevel form with the outer side occupying 2 / 3 of the wall thickness and the inner side occupying 1 / 3 of the wall thickness. The outer bevel angle is 30 degrees and the inner bevel angle is 45 degrees. The blunt edge dimension is 3mm. No local grinding of the edge is performed. S3. Perform outer circumferential welding at an inclination of 22.5 degrees. The welding torch moves from a high position to a low position. The two welding torches are arranged symmetrically with a distance of 180 degrees between them along the circumference of the tower. The welding currents are 180A and 200A respectively, with a difference of 11%. 25mm before each edge enters the welding area, the welder uses the arc-striking welding method to extinguish the arc briefly. After the vertex of the edge passes directly under the welding torch, the arc is reignited. S4. After the outer circumferential weld is completed, the root of the inner weld is cleaned by carbon planing. When carbon planing, start from the midpoint of each edge and extend the planing to both sides to form a V-shaped groove extending from the midpoint to both sides at each edge. The groove is 4mm deep and 10mm wide, so that the grooves between adjacent edges meet in the middle of the straight edge section. S5. After carbon planing is completed, the inner circumferential seam is welded. The first layer of weld fills the planing groove, and subsequent welds are stacked layer by layer until they are flush with the base material.

[0058] According to the flaw detection test, the first pass rate of the welded circumferential seam in this embodiment reached 94.3%, and the weld formation basically met the requirements. However, there were local excess heights at the edges, which required additional grinding.

[0059] Example 5 This embodiment provides a welding process for a polygonal tower and a cylindrical tube, the steps of which are as follows: S1. Place the 24-sided tower on the inclined fixture, adjust the circumferential phase of the tower so that the circumferential angle between the quadrilateral edge and the roller support point is greater than 30 degrees, then adjust the inclination angle of the fixture to 22.5 degrees so that the center of gravity of the tower is close to the inside of the fixture, and place the roller below the adjacent cylindrical tower section. S2. Adjust the welding bevel according to the 22.5-degree tilt angle, adopting an asymmetrical bevel form with the outer side occupying 2 / 3 of the wall thickness and the inner side occupying 1 / 3 of the wall thickness. The outer bevel angle is 30 degrees, the inner bevel angle is 45 degrees, and the blunt edge dimension is 3mm. Locally grind the bevel at each edge of the tower to reduce the outer bevel angle by 3 degrees within a 30mm range on both sides of the edge. S3. Perform outer circumferential welding at an inclination of 22.5 degrees. The welding torch moves from a high position to a low position. The two welding torches are arranged symmetrically with a distance of 180 degrees between them along the circumference of the tower. The welding currents are 180A and 200A respectively, with a difference of 11%. 25mm before each edge enters the welding area, the welder uses the arc-striking welding method to extinguish the arc briefly. After the vertex of the edge passes directly under the welding torch, the arc is reignited. S4. After the outer circumferential weld is completed, the root of the inner weld is cleaned by carbon planing. When carbon planing, start from any position and plan continuously around the circumference. The depth of the planing groove is 4mm and the width is 10mm. No special planing groove shape is formed at the edge. S5. After carbon planing is completed, the inner circumferential seam is welded. The first layer of weld fills the planing groove, and subsequent welds are stacked layer by layer until they are flush with the base material.

[0060] According to the flaw detection test, the first pass rate of the welded circumferential seam in this embodiment reached 93.7%, and the weld formation basically met the requirements. However, a slight dent appeared at the edge after the inner side was welded, which required local repair welding.

[0061] Comparative Example 1 This comparative example provides a welding process for a polygonal tower and a cylindrical tube, the steps of which are as follows: S1. Place the 24-sided tower section on the horizontal roller frame, with the rollers directly supporting the bottom of the polygonal tower section; S2. A symmetrical X-shaped bevel is adopted, with the outer and inner bevel angles both at 45 degrees and the blunt edge dimension at 2mm. S3. Perform outer circumferential weld in a horizontal position, keep the welding torch vertical, and use a welding current of 200A. S4. After the outer circumferential weld is completed, the root of the inner weld is cleaned by conventional carbon gouging. S5. After the carbon planing cleaning is completed, perform inner circumferential welding.

[0062] Flaw detection revealed that the first-pass yield of the circumferential weld in this comparative example was only 72.3%. The weld exhibited numerous defects, including incomplete fusion and slag inclusions. Severe weld protrusions at the edges required extensive grinding and rework. During welding, the tower exhibited significant vibration, posing a potential lateral tilting safety hazard.

[0063] Comparative Example 2 This comparative example provides a welding process for a polygonal tower and a cylindrical tube, the steps of which are as follows: S1. Place the 24-sided tower on the inclined fixture, adjust the inclination angle of the fixture to 22.5 degrees, so that the center of gravity of the tower is close to the inside of the fixture, and place the rollers below the adjacent cylindrical tower sections. S2. The bevel was not adjusted according to the tilt angle and a symmetrical X-shaped bevel was still used. The bevel angles of the outer and inner sides were both 45 degrees and the blunt edge size was 2mm. S3. Perform outer circumferential weld at a 22.5-degree angle, keeping the welding torch vertical and using a welding current of 200A. S4. After the outer circumferential weld is completed, the root of the inner weld is cleaned by conventional carbon gouging. S5. After the carbon planing cleaning is completed, perform inner circumferential welding.

[0064] The flaw detection results showed that the first-pass yield of the circumferential weld in this comparative example was 82.6%, which is an improvement over comparative example 1. However, defects such as incomplete fusion caused by arc deviation still exist, especially at the outer bevel where the welding wire deviates from the center, resulting in localized incomplete fusion. The weld formation is uneven, and there are still obvious protrusions at the edges.

[0065] Comparative Example 3 This comparative example provides a welding process for a polygonal tower and a cylindrical tube, the steps of which are as follows: S1. Place the 24-sided tower on the inclined fixture, adjust the inclination angle of the fixture to 22.5 degrees, so that the center of gravity of the tower is close to the inside of the fixture, and place the rollers below the adjacent cylindrical tower sections. S2. Adjust the welding bevel according to the tilt angle, adopting an asymmetrical bevel form with the outer side occupying 2 / 3 of the wall thickness and the inner side occupying 1 / 3 of the wall thickness. The outer bevel angle is 30 degrees and the inner bevel angle is 45 degrees, with a blunt edge dimension of 3mm; no local grinding of the edges was performed. S3. Perform outer circumferential welding at an inclination of 22.5 degrees, with the welding torch moving from a high position to a low position and a welding current of 200A. S4. After the outer circumferential weld is completed, the root of the inner weld is cleaned by conventional carbon gouging. Starting from any position, the arc is continuously gouged around the circumference. S5. After the carbon planing cleaning is completed, perform inner circumferential welding.

[0066] According to the flaw detection test, the first pass rate of the circumferential weld in this comparative example reached 88.9%, which is an improvement compared to comparative example 2. However, there are still some poor forming at the edges, and micro-cracks appeared at some edges after the inner side was welded, which require rework.

[0067] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A welding process for a polygonal tower and a cylindrical tube, characterized in that, Includes the following steps: S1. Place the tower on the inclined fixture, adjust the inclination angle of the fixture so that the center of gravity of the tower is close to the inside of the fixture, and place the rollers below the adjacent cylindrical tower sections. S2. Adjust the welding bevel according to the tilt angle, and adopt an asymmetrical bevel form in which the outer side occupies 1 / 2 to 2 / 3 and the inner side occupies 1 / 3 to 1 / 2; S3. Perform outer circumferential weld in an inclined state, and clean the root of the inner weld with carbon gouging after welding. S4. After the carbon planing cleaning is completed, perform inner circumferential welding.

2. The welding process according to claim 1, characterized in that, In S1, place the polygonal tower on the inclined fixture, adjust the circumferential phase of the tower so that its edges avoid the area directly above the roller support point, and then adjust the inclination angle of the fixture to 15~30 degrees.

3. The welding process according to claim 2, characterized in that, The processing method of the bevel described in S2 is as follows: First, a continuous outer bevel surface is processed along the circumference of the tower on the outside. Then, the bevel is locally ground at each edge of the polygonal tower so that the outer bevel angle within a range of 20-50mm on both sides of the edge is reduced by 2-5 degrees.

4. The welding process according to claim 3, characterized in that, After the beveling process described in S2 is completed, the beveling depth is measured along the circumference of the tower. Abnormal depth points are marked at the edges of the polygonal tower. Local repair welding and grinding are used to control the beveling depth deviation within ±2mm.

5. The welding process according to claim 3, characterized in that, The beveling process described in S2 and the adjustment of the tilt angle described in S1 have the following coordination relationship: The tilt angle θ set in S1 determines the flow direction of the molten pool metal under the action of gravity during welding. Based on θ, the theoretical angle β between the welding wire axis and the bevel sidewall is calculated, and then the theoretical value α of the outer bevel angle is determined, where α and β are complementary. First, an initial bevel with an outer bevel angle of α is processed. The tower is placed on the tilting fixture and rotated one revolution at the welding speed. The contact marks between the welding wire and the two sidewalls of the bevel are observed. If the marks are biased towards the outer sidewall of the bevel, the bevel angle is reduced by 1 to 2 degrees. If the marks are biased towards the inner sidewall, the bevel angle is increased by 1 to 2 degrees. The above observation and correction steps are repeated until the welding wire marks are located within the same width range on both sides of the bevel centerline.

6. The welding process according to claim 5, characterized in that, The outer circumferential weld described in S3 uses a symmetrical arrangement of two welding torches. The two welding torches are 180 degrees apart along the circumference of the tower and both move from the high position to the low position. The welding current of the two welding torches differs by 10% to 15%.

7. The welding process according to claim 5, characterized in that, After the first layer of weld bead for the outer circumferential seam welding described in S3 is completed, welding is paused, the tower is rotated 180 degrees in the opposite direction, and then the second layer of weld bead is welded from the high position to the low position in the opposite direction, so that the fusion direction of adjacent weld bead bead intersects with each other.

8. The welding process according to claim 5, characterized in that, When welding the outer circumferential seam as described in S3, the welder uses the arc-striking welding method to briefly extinguish the arc 20-30mm before each polygonal edge enters the welding area. After the vertex of the edge passes directly below the welding gun, the arc is re-ignited. By controlling the arc interruption time, the molten pool metal forms a continuous transition on both sides of the edge.

9. The welding process according to claim 5, characterized in that, The carbon planing cleaning described in S3 includes the following steps: After the outer circumferential weld is completed, carbon planing is performed at the root of the inner weld along the circumference of the tower. During carbon planing, the arc is started from the midpoint of each edge of the polygonal tower and the planing extends to both sides of the edge, forming a V-shaped groove extending from the midpoint to both sides at each edge, so that the grooves between adjacent edges meet in the middle of the straight edge section.

10. A welding apparatus for a polygonal tower and a cylindrical tube, used to implement the welding process described in any one of claims 1-9, characterized in that, It includes an inclined fixture and a reinforcing ring plate (5); the inclined fixture includes a base (1), an inclined support structure (2) and an angle adjustment mechanism (3), the inclined support structure (2) is connected to the base (1), and the angle adjustment mechanism (3) is used to adjust the inclination angle of the inclined support structure (2); the inclined support structure (2) is provided with a roller mounting position (4); the reinforcing ring plate (5) is a contoured structure adapted to a cylinder and fits the side of the cylindrical tower section.

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