A kind of multi-pass full penetration welding process of multi-layer structure with right-angle bending

Abstract

The present application belongs to the technical field of welding manufacturing of large steel structure, and particularly relates to a multi-layer and multi-pass full penetration welding process for a right-angle structure. The welding process comprises the following steps: cutting a double-sided asymmetric groove on a rib plate, one side of which is a large groove and the other side is a small groove, and polishing the groove; fixing the rib plate and a spoke plate on the small groove side by using a process triangular plate; welding the rib plate and an outer ring as well as the spoke plate, the rib plate and the spoke plate being welded as horizontal welding, and the rib plate and the outer ring being welded as vertical welding, and removing the process triangular plate; and performing non-destructive testing and annealing heat treatment on the weld. The welding process reduces labor intensity, improves the working environment, and ensures the stability and consistency of the welding quality.

Description

Technical Field

[0001] This invention belongs to the field of welding and manufacturing technology for large steel structural components, specifically relating to a multi-layer, multi-pass full penetration welding process for right-angle structures. Background Technology

[0002] In the manufacturing of large steel structural components, such as engineering machinery and heavy machinery products, stiffening plates are a common reinforcing structure. They are typically right-angled triangular steel plates, with the two right-angled sides of the stiffening plate connected and reinforced to two components by welding, forming a right-angled structure. A typical large dissimilar metal structural component consists of an outer ring 9, spokes 10, and stiffening plates 11. The welds between the stiffening plates and the outer ring and spokes form a right-angled structure. A partial structural diagram is shown below. Figure 1 As shown. The outer ring is usually made of medium carbon quenched and tempered steel forgings and is arc-shaped to ensure its high strength and wear resistance; while the spokes and stiffeners are made of ordinary high-strength steel plates, and the stiffeners are evenly distributed around the circumference.

[0003] In this type of structure, the connections between the stiffening plates, outer ring, and spokes are all double-bevel joints, commonly symmetrical double-bevel joints. These joints are prone to deformation during welding, requiring full penetration welding to ensure joint strength. Furthermore, stringent requirements are placed on material cutting and assembly precision, necessitating a tight fit (gap <1mm) welding process. Additionally, because the outer ring is made of medium-carbon quenched and tempered steel with a high carbon equivalent and a strong hardening tendency, its weldability is poor, making it highly susceptible to cold and hot cracking during welding, thus affecting weld quality.

[0004] In addition, to prevent cracking, the outer ring must be preheated before welding, typically to a temperature above 200°C, and the interpass temperature must be strictly maintained during welding. Welding of this type of structure relies heavily on manual operation. Under high preheating temperatures (above 200°C), the welding of the stiffening plates (horizontal welding between the stiffening plates and spokes, and vertical welding between the stiffening plates and the outer ring) exposes welders to prolonged periods in high-temperature, confined working environments. This involves a large number of welders, resulting in extremely high labor intensity, harsh working conditions, and safety hazards. Furthermore, prolonged high-temperature work easily leads to welder fatigue, making it difficult to maintain consistent welding techniques. This results in poor weld uniformity, large fluctuations in internal quality, and a high rework rate, severely impacting the product's manufacturing cycle and service reliability. Summary of the Invention

[0005] To address the shortcomings of existing methods, this invention provides a multi-layer, multi-pass full penetration welding process for right-angle structures, which reduces labor intensity, improves the working environment, and ensures the stability and consistency of welding quality.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A multi-layer, multi-pass full-penetration welding process for a right-angled structure includes the following steps: S1. Cut a double-sided asymmetrical bevel on the stiffener plate, with a large bevel on one side and a small bevel on the other side, and grind the bevel. S2. Use a process triangle plate to fix the stiffening plate and the spoke plate on the small bevel side; S3. Weld the stiffening plate to the outer ring and the spokes. The welding of the stiffening plate to the spokes is a horizontal weld, and the welding of the stiffening plate to the outer ring is a vertical weld. Remove the process triangle plate. S4. Non-destructive testing and annealing heat treatment of welds.

[0007] Preferably, the large bevel angle in step S1 is 35-45°, the small bevel angle is 40-50°, the depth ratio of the large bevel to the small bevel is 1.5-2.5:1, and the blunt edge length is 0-2mm.

[0008] Preferably, in step S2, one side of the process triangle plate is welded to the spoke plate and the other side is welded to the stiffener plate, and the assembly gap between the stiffener plate and the outer ring and spoke plate is 3-4mm.

[0009] Preferably, in step S3, the vertical welding position is preheated to 200-300℃ before welding, and the interlayer temperature of the vertical welding is controlled at 200-300℃ during welding; the horizontal welding position is preheated to 110-180℃ before welding, and the interlayer temperature of the horizontal welding is controlled at 110-180℃ during welding.

[0010] Preferably, the welding method in step S3 is multi-layer, multi-pass gas shielded welding using a robot.

[0011] Preferably, the multi-layer multi-pass gas shielded welding steps are as follows: according to the welding joint process database, the first weld is manually taught and welded; for subsequent welds, the corresponding weld data in the welding joint database is selected; the system automatically calculates and generates the welding trajectory and process parameters of each subsequent pass based on the actual position of the first weld, and then offsets and completes the welding of other welds.

[0012] Preferably, the welding sequence of the stiffening plate, outer ring, and spokes in step S3 is as follows: S31, horizontal welding with large bevel for root pass; S32. Vertical weld with large bevel for root pass, and fill halfway; S33, fill half of the horizontal weld bevel; S34. Remove the process triangle plate and horizontally weld the small bevel as the base; S35. Vertical welding with a small bevel for the root pass, followed by filling and covering. S36. Filling and covering of the horizontal weld bevel; S37. Fill the remaining half of the vertical weld bevel and cover it; S38, fill the remaining half of the horizontal weld bevel and cover it.

[0013] Preferably, the horizontal welding root pass process parameters are: current 200-300A, voltage 29-32V, welding speed 250-350mm / min; the horizontal welding fill or cover pass process parameters are: current 250-350A, voltage 29-36V, welding speed 250-400mm / min.

[0014] Preferably, the vertical welding root pass process parameters are: current 160-220A, voltage 19-25V, welding speed 40-80mm / min; the vertical welding fill or cover pass process parameters are: current 180-250A, voltage 20-26V, welding speed 40-70mm / min.

[0015] Preferably, the fillet weld formed on the cover extends to both sides of the stiffener plate for a length of 0-0.7 times the thickness of the stiffener plate.

[0016] The positive and beneficial effects of this invention are: 1. This invention takes into account the uniform distribution of heat and the control of deformation during the welding process. During welding, large and small bevels are welded alternately, and horizontal and vertical welds are welded alternately. This determines a reasonable welding sequence and welding parameters. Moreover, the bevel form of this invention has a strong tolerance for the welding parameters, which can well guarantee the quality of the weld.

[0017] 2. This invention uses a large bevel angle of 35-45° and a small bevel angle of 40-50°, with a depth ratio of 1.5-2.5:1 between the large and small bevels. The blunt edge length of the blank is 0-2mm, which better controls deformation. The assembly gap is widened to 3-4mm, which greatly reduces the stringent requirements for blanking accuracy and assembly accuracy. Compared with the traditional welding process that requires tight fit (gap <1mm), this invention has a stronger tolerance for incoming material errors, reduces rework caused by assembly deviations, and achieves excellent weld penetration, ensuring weld quality and a high flaw detection pass rate.

[0018] 3. This invention uses robots to perform multi-layer, multi-pass gas shielded welding, freeing workers from high-temperature and high-heat radiation environments above 200°C, reducing labor intensity. Moreover, the welds welded by robots have good consistency, reducing the uncertainty of manual operation in high-temperature environments, and the welds are aesthetically pleasing with a high pass rate for flaw detection. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a partial assembly structure of the stiffening plate, outer ring, and spokes in the prior art; Figure 2 This is a schematic diagram of a stiffener plate structure; Figure 3 This is a schematic diagram showing the dimensions of the rib bevel. Figure 4 This is a schematic diagram of a partial assembly structure of the stiffener, outer ring, and spokes of the present invention. Figure 5 This is a schematic diagram of the process triangle plate structure; Figure 6 This is a diagram illustrating the welding sequence; Figure 7 This is a schematic diagram of the structure after welding the bevel of the stiffening plate; In the diagram: 1-Horizontal weld with large bevel for root pass, 2-Vertical weld with large bevel for root pass and fill to half, 3-Horizontal weld with large bevel for half pass, 4-Horizontal weld with small bevel for root pass, 5-Vertical weld with small bevel for root pass, and fill and cover, 6-Horizontal weld with small bevel for filling and cover, 7-Vertical weld with large bevel for filling the remaining half and cover, 8-Horizontal weld with large bevel for filling the remaining half and cover, 9-Outer ring, 10-Spoke plate, 11-Firming plate, 12-Process triangle plate. Detailed Implementation

[0020] The present invention will be further described below with reference to some specific embodiments.

[0021] Example 1

[0022] A multi-layer, multi-pass, full-penetration welding process for a right-angled structure, the right-angled structure including an outer ring 9, spoke plates 10, and stiffening plates 11, the outer ring being made of 34CrNi1Mo, and the stiffening plates and spoke plates being made of Q355B, including the following steps: S1. Taking a 60mm thick stiffening rib as an example, see [link / reference]. Figure 2 A beveling robot was used to cut a double-sided asymmetrical bevel on the welded surface of the stiffener plate. The larger bevel angle was 40° and the bevel depth was 39mm, while the smaller bevel angle was 45° and the bevel depth was 19mm. The blunt edge length was 2mm. The bevel dimensions are shown in [reference needed]. Figure 3 As shown, the bevel is polished to ensure a smooth surface and expose the metallic luster; S2. The assembly gap between the stiffening plate and the outer ring and spokes is controlled to be 3mm. During assembly, the stiffening plate 11 is fixed to the spokes 10 using the process triangle 12 on the small bevel side. One side is welded to the spokes 10, and the other side is welded to the stiffening plate 11. The stiffening plate is not directly fixed to the outer ring and spokes. See [link to documentation]. Figure 4 As shown; the specifications of the process triangle are: thickness δ 10mm, length of both sides 120mm, material Q235B, see... Figure 5 As shown, each stiffening plate is fixed using two process triangle plates; S3. The welding of the stiffening plate and the spoke plate is a horizontal welding, and the welding of the stiffening plate and the outer ring is a vertical welding. Before welding, the vertical welding position is preheated to 200-300℃, and the outer circle of the outer ring is heated by flame or electromagnetic induction. During welding, the interlayer temperature of the vertical welding is controlled at 200-300℃. Before welding, the horizontal welding position is preheated to 110-180℃, and the spoke plate is heated by flame. During welding, the interlayer temperature of the horizontal welding is controlled at 110-180℃. S4. Use a robot to perform multi-layer, multi-pass gas shielded welding, using ER50-6 welding wire with a diameter of 1.2mm. For welding parameters, see Table 1-2. First, manually teach and weld the first weld (the first weld of horizontal large bevel, horizontal small bevel, vertical large bevel, and vertical small break). For subsequent welds, select the corresponding weld data in the welding joint database, and then offset and weld according to the position of the first weld. Methods for constructing a weld joint database: When welding the first piece, determine the welding parameters for each weld pass and save them to the database. After the stiffener plate of the first piece is welded, a weld joint database is formed; or a partial simulation of the weld joint is made, welding tests are conducted, the welding parameters for each weld pass are determined, and a weld joint database is formed. The above welding parameters mainly include offset, oscillation width, oscillation frequency, current, voltage, wire feed speed, and welding speed.

[0023] Table 1. Parameters for horizontal welding of stiffening plates

[0024] Table 2. Vertical Welding Process Parameters for Rib Plates

[0025] The specific welding sequence is as follows, see Figure 6 : S41, horizontal welding with large bevel for root pass, marked as serial number 1; S42. For vertical welding, make a large bevel for the root pass and fill it to halfway, which is recorded as serial number 2; S43. Fill the horizontal weld groove to halfway, and mark it as serial number 3. S44. Remove the process triangle plate, horizontally weld the small bevel as the base, and record it as serial number 4. S45. Vertical welding with a small bevel for the root pass, followed by filling and covering, is recorded as serial number 5. S46, horizontal weld small bevel filling and cover, marked as serial number 6; S47, fill the remaining half of the vertical weld bevel and cover it, which is recorded as serial number 7; S48, the remaining half of the horizontal weld bevel filler and cover, marked as serial number 8; see the schematic diagram of the post-weld structure of the stiffener bevel. Figure 7 The fillet weld formed on the cover extends to both sides of the stiffening plate by 15mm; S5. After welding, perform ultrasonic and magnetic particle non-destructive testing on the weld and promptly perform annealing heat treatment to eliminate welding stress.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A multi-layer, multi-pass full penetration welding process for a right-angle structure, characterized in that, Includes the following steps: S1. Cut a double-sided asymmetrical bevel on the stiffener plate, with a large bevel on one side and a small bevel on the other side, and grind the bevel. S2. Use a process triangle plate to fix the stiffening plate and the spoke plate on the small bevel side; S3. Weld the stiffening plate to the outer ring and the spokes. The welding of the stiffening plate to the spokes is a horizontal weld, and the welding of the stiffening plate to the outer ring is a vertical weld. Remove the process triangle plate. S4. Non-destructive testing and annealing heat treatment of welds.

2. The multi-layer, multi-pass full penetration welding process for right-angle structures according to claim 1, characterized in that, In step S1, the large bevel angle is 35-45°, the small bevel angle is 40-50°, the depth ratio of the large bevel to the small bevel is 1.5-2.5:1, and the blunt edge length is 0-2mm.

3. The multi-layer, multi-pass full penetration welding process for right-angle structures according to claim 1, characterized in that, In step S2, one side of the process triangle plate is welded to the spoke plate, and the other side is welded to the stiffening plate. The assembly gap between the stiffening plate and the outer ring and spoke plate is 3-4mm.

4. The multi-layer, multi-pass full penetration welding process for right-angle structures according to claim 1, characterized in that, Before welding in step S3, preheat the vertical welding position to 200-300℃, and control the interpass temperature of the vertical welding to 200-300℃ during welding; before welding the horizontal welding position, preheat the horizontal welding position to 110-180℃, and control the interpass temperature of the horizontal welding to 110-180℃ during welding.

5. The multi-layer, multi-pass full penetration welding process for right-angle structures according to claim 4, characterized in that, The welding method described in step S3 is to use a robot to perform multi-layer, multi-pass gas shielded welding.

6. The multi-layer, multi-pass full penetration welding process for right-angle structures according to claim 5, characterized in that, The multi-layer, multi-pass gas shielded welding steps are as follows: based on the welding joint process database, the first weld is manually taught and welded; for subsequent welds, the corresponding weld data in the welding joint database is selected; the system automatically calculates and generates the welding trajectory and process parameters for each subsequent pass based on the actual position of the first weld, and then offsets and completes the welding of other welds.

7. The multi-layer, multi-pass full penetration welding process for right-angle structures according to claim 6, characterized in that, The welding sequence of the stiffening plate, outer ring, and spokes in step S3 is as follows: S31, horizontal welding with large bevel for root pass; S32. Vertical weld with large bevel for root pass, and fill halfway; S33, fill half of the horizontal weld bevel; S34. Remove the process triangle plate and horizontally weld the small bevel as the base; S35. Vertical welding with a small bevel for the root pass, followed by filling and covering. S36. Filling and capping of the horizontal weld bevel; S37. Fill the remaining half of the vertical weld bevel and cover it; S38, fill the remaining half of the horizontal weld bevel and cover it.

8. The multi-layer, multi-pass full penetration welding process for right-angle structures according to claim 7, characterized in that, The horizontal welding root pass process parameters are: current 200-300A, voltage 29-32V, welding speed 250-350mm / min; the horizontal welding fill or cover pass process parameters are: current 250-350A, voltage 29-36V, welding speed 250-400mm / min.

9. The multi-layer, multi-pass full penetration welding process for right-angle structures according to claim 7, characterized in that, The parameters for the vertical welding root pass are: current 160-220A, voltage 19-25V, welding speed 40-80mm / min; the parameters for the vertical welding fill or cover pass are: current 180-250A, voltage 20-26V, welding speed 40-70mm / min.

10. The multi-layer, multi-pass full penetration welding process for right-angle structures according to claim 7, characterized in that, The fillet weld formed on the cover extends to both sides of the stiffener plate for a length of 0-0.7 times the thickness of the stiffener plate.

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