Box type cantilever crane and welding method thereof

Abstract

The embodiment of the invention provides a box type cantilever crane and a welding method thereof. The method comprises the steps that a first side plate, a second side plate, a third side plate and a fourth side plate are pre-fixed through a retainer, so that the first side plate and the second side plate are oppositely arranged, and the third side plate and the fourth side plate are oppositely arranged; firstly, the first side plate and the third side plate are welded and fixed in a ship-shaped welding mode, and the second side plate and the fourth side plate are welded and fixed in a ship-shaped welding mode; and then the second side plate and the third side plate are welded and fixed in a ship-shaped welding mode, and the first side plate and the fourth side plate are welded and fixed in a ship-shaped welding mode. According to the method, the welding sequence is set to be that one set of opposite angles of the side plates are welded firstly, then the other set of opposite angles are welded, the stable foundation frame structure can be rapidly formed through the welding sequence, and initial symmetric balance of welding heat input and shrinkage stress is macroscopically achieved.

Description

Technical Field

[0001] This application relates to the field of engineering machinery technology, and in particular to a box-type boom and its welding method. Background Technology

[0002] In the manufacturing process of box-type boom structures, welding is a key process that determines the final quality and dimensional accuracy of the product. However, if the welding process parameters are not set properly or are not well matched with the structural characteristics, it can easily lead to internal defects such as poor weld fusion, porosity, and slag inclusions, as well as more prominent welding deformation problems.

[0003] While several improvement schemes have been proposed in related technologies, limitations still exist in practical applications: these technologies mostly focus on local optimization of specific joint types or filler groove designs, lacking overall deformation control capabilities. Although they help improve the quality of local welds, they fail to systematically solve the macroscopic overall deformation of the box-type boom caused by the accumulation and mutual constraints of welding deformation from multiple components such as cover plates, web plates, and diaphragms.

[0004] In addition, the relevant welding process methods are usually set for a single plate thickness, and there is a lack of coordinated control strategies applicable to multiple plate thicknesses in the same boom structure, making it difficult to achieve precise control of welding deformation of complex box booms. Summary of the Invention

[0005] This application provides a box-type boom and its welding method, which can comprehensively regulate the cumulative welding deformation of multiple components and adapt to coordinated control schemes for various plate thickness conditions within the same boom, thereby achieving precise control of welding deformation. This addresses the problems of lack of systematic control and insufficient versatility of process strategies in box-type boom welding deformation control.

[0006] In a first aspect, embodiments of this application provide a welding method for a box-type boom, comprising:

[0007] The first side plate, the second side plate, the third side plate, and the fourth side plate are pre-fixed by a retainer, so that the first side plate and the second side plate are arranged opposite to each other, and the third side plate and the fourth side plate are arranged opposite to each other.

[0008] First, the first side plate and the third side plate are welded and fixed using a ship-shaped welding method. Then, the second side plate and the fourth side plate are welded and fixed using a ship-shaped welding method. Next, the second side plate and the third side plate are welded and fixed using a ship-shaped welding method. Finally, the first side plate and the fourth side plate are welded and fixed using a ship-shaped welding method.

[0009] This application sets the welding sequence to first weld one set of diagonal side plates, then weld another set of diagonal side plates. This welding sequence can quickly form a stable basic frame structure and achieve a preliminary symmetrical balance between welding heat input and shrinkage stress on a macroscopic scale.

[0010] In one possible implementation, the first side plate and the third side plate form filling grooves, and the cross-sectional width of the filling grooves gradually increases from the bottom of the grooves to the opening of the grooves. By directly forming the filling grooves at the ends of multiple side plates, the process of separately beveling can be eliminated, which simplifies the manufacturing process and improves material utilization.

[0011] The first side plate and the third side plate are welded and fixed by a ship-shaped welding method, including: forming a base layer in the filling groove, wherein the base layer fills the bottom of the filling groove; ensuring that the root of the filling groove is fully melted to provide basic positioning and structural strength for subsequent welding.

[0012] A cover layer is formed on the bottom layer, and at least a portion of the cover layer extends out of the opening of the filling groove. This ensures that the weld is aesthetically pleasing and dimensionally uniform, and eliminates welding defects such as undercut, weld beads, and lack of fusion.

[0013] In one possible implementation, the thickness of the first side plate and the thickness of the third side plate are less than or equal to 8 mm, and the cover layer is bonded to the underlayer. This reduces the number of welding layers while ensuring welding strength, lowering the overall heat input, effectively reducing welding shrinkage and deformation, and improving the dimensional accuracy and production efficiency of the box-type boom.

[0014] In one possible implementation, the underlayer is formed in the filling groove, and the underlayer is welded using a small-amplitude serrated oscillating welding head with an oscillation frequency of 2.5 Hz, an oscillation width of 2.5 mm, and a welding speed of 20~35 cm / min.

[0015] The above-described embodiments can control the heat input of a single welding pass within a reasonable range, ensuring full penetration at the weld root while effectively suppressing initial deformation.

[0016] After a single weld is completed in one continuous operation, its diagonal welds are welded sequentially using the same process parameters. Then, another set of diagonal welds is welded. This process ensures that the welding heat input and shrinkage stress are structurally balanced, further reducing overall welding deformation and improving the dimensional accuracy and structural stability of the box-type boom.

[0017] In one possible implementation, the cover layer is welded using a small-amplitude serrated oscillating welding head with an oscillation frequency of 2.5 Hz, an oscillation width of 3 mm, and a welding speed of 30 cm / min.

[0018] By using the above process parameters, it is possible to ensure that the weld surface is flat and the contour is uniform, without appearance defects such as undercut and weld beads. While ensuring the quality of weld formation, it is also possible to effectively control the welding heat input and further suppress welding deformation.

[0019] In one possible implementation, when the thickness of the first side plate and the thickness of the third side plate are greater than 8 mm, a filler layer is also formed between the base layer and the top layer, the filler layer covering the base layer.

[0020] The above-described embodiments of this application can flexibly adjust the number of welding layers and welding process for different plate thicknesses, achieve precise coordination and control of welding heat input and structural deformation, and ensure stable and reliable welding quality and dimensional accuracy under different plate thickness conditions.

[0021] In one possible implementation, the filler layer is welded using a small-amplitude serrated oscillating welding head with an oscillation frequency of 2.5 Hz, an oscillation width of 4.2~4.5 mm, and a welding speed of 25~45 cm / min.

[0022] The above process parameters can stably control the heat input of a single pass, ensuring good fusion between the filler layer, the root pass, and the side walls, and avoiding defects such as slag inclusions and incomplete fusion. Appropriate swing amplitude and welding speed allow for uniform filling of the bevel layer by layer, ensuring weld density and structural strength. Simultaneously, precise control of heat accumulation suppresses interlayer deformation, providing a flat and uniform support surface for subsequent cover layer welding, further improving the overall weld quality and dimensional accuracy.

[0023] In one possible implementation, the first side plate, second side plate, third side plate, and fourth side plate are pre-fixed by a retainer, including:

[0024] The first side plate, the second side plate, the third side plate, and the fourth side plate are installed using tooling, with the first side plate and the second side plate facing each other, and the third side plate and the fourth side plate facing each other. The retainer is placed in the internal space formed by the multiple side plates, and the retainer is tightly fitted to the inner walls of the multiple side plates. The retainer is temporarily fixed to each side plate by spot welding.

[0025] By pre-fixing the first, second, third, and fourth side plates with retainers, each side plate can be positioned before welding and form a stable box-shaped frame structure, ensuring that the relative positions of each side plate are accurate and the spacing is uniform.

[0026] The cage fits tightly against the inner wall of each side plate, which can significantly improve the overall rigidity of the structure during welding, effectively resist the lateral shrinkage and deformation caused by welding thermal stress, and improve the dimensional accuracy and structural stability of the box-type boom.

[0027] Secondly, embodiments of this application provide a box-type boom, which is manufactured using the box-type boom welding method described in any of the above possible embodiments.

[0028] By specifying that the box-shaped boom is manufactured using the aforementioned welding method, the box-shaped boom has technical advantages such as small welding deformation, high structural strength, stable weld quality, and better finished product precision and reliability.

[0029] In one possible implementation, the box-type boom includes a plurality of side plates, the plurality of side plates including a first side plate, a second side plate, a third side plate and a fourth side plate;

[0030] A filling groove is provided between two adjacent side plates. The cross-sectional width of the filling groove gradually increases from the bottom of the groove to the opening of the groove. This facilitates the gradual increase of the welding operation space, improves the quality of weld formation, and reduces welding stress concentration, thereby reducing the risk of welding cracks.

[0031] The filling groove is provided with a base layer, a filling layer and a cover layer stacked sequentially from the bottom of the groove to the opening of the groove. The base layer is located at the bottom of the filling groove and is used to seal the filling groove and provide basic positioning and structural strength for subsequent welding; ensuring the initial stability of the overall structure.

[0032] The rigidity of the filling layer is higher than that of the base layer and the top layer, which can significantly improve the connection rigidity between adjacent side plates of the box boom and enhance the overall load-bearing capacity of the box boom.

[0033] At least a portion of the cover layer extends out of the groove. The cover layer has a smooth surface, which can effectively cover and protect the welding inside the filling groove, and improve the appearance quality of the weld.

[0034] The box-type boom's overall structure, through its layered functional design, balances weldability, structural strength, and appearance quality, resulting in enhanced welding reliability, more uniform stress distribution, and a longer service life. Attached Figure Description

[0035] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0036] Figure 1 This is a schematic diagram of the overall structure of the box-type boom provided in this application;

[0037] Figure 2 This is a structural schematic diagram of the top view of the box-type boom provided in this application;

[0038] Figure 3 This is a top view schematic diagram of the box-type boom welding structure provided in Embodiment 1 of this application;

[0039] Figure 4 This is a top view schematic diagram of the box-type boom welding structure provided in Embodiment 2 of this application;

[0040] Figure 5 This is a top view schematic diagram of the box-type boom welding structure provided in Embodiment 3 of this application;

[0041] Figure 6 This is a top view schematic diagram of the box-type boom welding structure provided in Embodiment 4 of this application;

[0042] Figure 7 A flowchart illustrating the welding method for the box-type boom provided in this application.

[0043] Explanation of reference numerals in the attached figures:

[0044] 100 - Box-type boom; 110 - First side plate; 120 - Second side plate; 130 - Third side plate; 140 - Fourth side plate; 150 - Filling groove; 151 - Groove opening; 152 - Groove bottom;

[0045] 200-cage;

[0046] 310 - Base coat; 320 - Filler layer; 321 - First filler layer; 322 - Second filler layer; 323 - Third filler layer; 330 - Top coat; 331 - First top coat; 332 - Second top coat; 333 - Third top coat;

[0047] 400 - Welding torch; 410 - Welding head.

[0048] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0049] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0050] First, let me explain the terms used in this application:

[0051] Beveling: According to welding design or process requirements, a groove with a specific geometric shape is pre-processed on the part of the workpiece to be welded. This is used to ensure weld penetration, facilitate welding operations, and control weld formation and welding stress.

[0052] This application provides a box-type boom and its welding method, which can comprehensively regulate the cumulative welding deformation of multiple components and adapt to coordinated control schemes for various plate thickness conditions within the same boom, thereby achieving precise control of welding deformation. This addresses the problems of lack of systematic control and insufficient versatility of process strategies in box-type boom welding deformation control.

[0053] Traditional closed box-type boom structures, formed by joining four plates of equal thickness at their ends, offer advantages such as no need for beveling and high fatigue strength. However, the initial contact at the joints of this type of structure results in poor overall assembly stability. During welding, it is highly susceptible to twisting, warping, and other welding deformations, which severely affect the boom's dimensional accuracy, structural strength, and performance.

[0054] After research, the inventors discovered that welding deformation is mainly caused by longitudinal shrinkage of the weld. The amount of longitudinal shrinkage ∆L is positively correlated with the total heat input Q of the weld, and the relationship can be expressed as follows:

[0055] ∆L∝(Q∙L) / (A∙c∙ρ)α

[0056] Where L is the weld length, A is the cross-sectional area of ​​the component, c is the specific heat capacity, ρ is the density, and α is the coefficient of thermal expansion.

[0057] The total welding heat input Q is related to the arc heating effect η, the arc voltage U, the welding current I, and the welding speed v, and can be expressed by the following formula:

[0058] Q=η∙(U∙I) / v

[0059] In summary, the objective of this application is to reduce the post-weld overall deformation D. turn Minimize this variable; it can be represented as a function of multiple process variables.

[0060] D turn =f(Q layer ,k,s)

[0061] Q layer is the interlayer heat input, k is the structural system stiffness, s is the symmetry welding sequence factor defined in this patent, and is a dimensionless coefficient used to characterize the efficiency of stress cancellation.

[0062] Post-weld overall deformation D turn interlayer heat input Q layer The deformation is a function of multiple process parameters, including structural system stiffness k and symmetry welding sequence factor s. Therefore, the magnitude and distribution of welding heat input are key factors controlling the welding deformation of the box-type boom.

[0063] Currently, conventional welding processes do not provide refined heat input control and welding sequence optimization for this type of enclosed box-shaped structure made of plates of equal thickness. This makes it difficult to achieve coordinated control of welding stress and deformation, and thus cannot meet the manufacturing requirements of high-precision box-shaped booms.

[0064] Therefore, this application aims to solve the technical problem that existing closed box-type booms composed of four plates of equal thickness are prone to twisting and warping deformation during the welding process, and to provide a refined welding process method that can effectively control welding deformation and achieve synergistic control of welding stress and deformation.

[0065] To achieve the above objectives, this application adopts the following technical solution:

[0066] A welding process for a box-type boom, wherein the box-type boom 100 is formed by joining four plates of equal thickness at their ends to create a closed box-type structure, and by combining a symmetrical welding sequence, a unit continuous welding method, and internal rigid support cage, the welding heat input and structural stiffness are synergistically controlled. The specific principle is as follows:

[0067] 1. Active control: Refined management and control of welding heat input.

[0068] By reasonably increasing the number of welding layers, the concentrated high heat input is decomposed into multiple passes and small-amplitude layer-average heat inputs, making the temperature field distribution in the weld area more gradual, reducing the thermal shock caused by severe nonlinear thermal cycling, thereby significantly suppressing weld angular deformation and longitudinal shrinkage, and reducing the overall welding deformation caused by longitudinal shrinkage.

[0069] 2. Passive control: Strengthening the overall stiffness of the structure.

[0070] A retainer 200 is installed inside the box-type boom 100 to enhance the overall system stiffness k of the component during welding through rigid support. Under the same welding shrinkage stress, the amount of structural deformation is inversely proportional to the stiffness. Increasing the stiffness can effectively reduce the structural deformation under welding stress, thereby achieving passive suppression of welding deformation.

[0071] 3. Symmetrical welding sequence stress offset control.

[0072] Please refer to Figure 2 The included angle formed by the first side plate 110 and the third side plate 130 is defined as included angle A, the included angle formed by the second side plate 120 and the third side plate 130 is defined as included angle B, the included angle formed by the second side plate 120 and the fourth side plate 140 is defined as included angle C, and the included angle formed by the first side plate 110 and the fourth side plate 140 is defined as included angle D.

[0073] After each layer of weld in area A is completed, areas C, B, and D are welded sequentially according to the same process parameters and operating requirements; the welding sequence between areas follows a symmetrical path of A→C→B→D.

[0074] When fillet welds are applied sequentially, the resulting welding thermal stress and shrinkage deformation are symmetrically distributed along the diagonal of the boom. The shrinkage stress of one set of fillet welds can symmetrically cancel out the shrinkage stress of another set of diagonals. This symmetrical path achieves the orderly release and mutual cancellation of welding stress. The sequence factor s ensures that the stress cancellation efficiency is not less than 85%, further reducing the overall post-weld deformation D. turn .

[0075] Meanwhile, this welding sequence allows the frame to maintain relatively free deformation space during the welding process, avoiding stress concentration caused by excessive local restraint. Heat input is evenly conducted along the diagonal direction, reducing residual welding stress and welding deformation, thereby ensuring the dimensional accuracy and structural stability of the box-type boom.

[0076] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0077] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclusively include, for example, a product or device that includes a series of components is not necessarily limited to those that are explicitly listed, but may include other components that are not explicitly listed or that are inherent to such product or device.

[0078] In the description of this application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0079] The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0080] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0081] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0082] Figure 1 This is a schematic diagram of the overall structure of the box-type boom provided in the embodiments of this application, as shown below. Figure 1 As shown, in a first aspect, embodiments of this application provide a welding method for a box-type boom, comprising:

[0083] The four side panels, after being cut and edge-processed, are placed on a special assembly fixture for assembly. During the assembly process, retainers 200 are riveted inside to pre-fix the first side panel 110, the second side panel 120, the third side panel 130, and the fourth side panel 140, so that the first side panel 110 and the second side panel 120 are positioned opposite each other, and the third side panel 130 and the fourth side panel 140 are positioned opposite each other, forming a box-shaped cross-section.

[0084] To ensure equal strength matching between the weld metal and the base metal, while also considering good welding process performance, this embodiment preferably uses JQ MG70S-6 solid welding wire for the welding operation. The diameter of this welding wire is set to 1.2 mm, and the connection process is completed using MAG (Metal Injection Gas) welding technology. By using the above-mentioned matching combination of welding wire type and diameter, the strength performance of the welded joint can be effectively guaranteed to be comparable to that of the base metal, while maintaining stable weld formation quality.

[0085] The welding operation was carried out using a KRⅡ500 carbon dioxide gas shielded welding machine, and the welding equipment was in normal working condition and operating stably. Before welding, the area to be welded and the area within 20-50 mm on both sides were cleaned to thoroughly remove surface moisture, rust, oil, oxide scale and other impurities, so that the surface of the side plate was exposed with a metallic luster.

[0086] Before formal welding, a trial welding operation is conducted to determine and verify appropriate welding process parameters, ensuring stable and reliable welding quality.

[0087] For example, please refer to Figure 7 First, clamps are used to initially fix each side plate, and the relative positions of each side plate are adjusted to ensure uniform gaps. Optionally, the gaps can be controlled within the range of 0.5-2 mm. Then, intermittent spot welding is used to perform tack welding on the cage 200 and each side plate. Optionally, the tack weld length is 30-50 mm, the weld spacing is 300-400 mm, the welding parameters are slightly lower than the formal welding parameters, and the shielding gas flow rate is controlled at 18-22 L / min. This forms a structure with sufficient initial rigidity and dimensional accuracy to meet the welding requirements.

[0088] First, the first side plate 110 and the third side plate 130 are welded and fixed using a ship-shaped welding method, and weld seam A is continuously welded along the entire length of the side plates. Then, the second side plate 120 and the fourth side plate 140 are welded and fixed using the same method. Weld seam C is then adjusted to a horizontal position and continuously welded along its entire length. Next, the second side plate 120 and the third side plate 130 are welded and fixed using the same method. Weld seam B is then adjusted to a horizontal position and continuously welded along its entire length. Finally, the first side plate 110 and the fourth side plate 140 are welded and fixed using the same method. Weld seam D is then adjusted to a horizontal position and continuously welded along its entire length.

[0089] Figure 2 This is a structural schematic diagram of the box-type boom 100 provided in this application, shown in the top view; it can be based on... Figure 2 Refer to the relative positions of each side plate. That is, weld in the order of ACBD. This application sets the welding sequence to weld one set of diagonal sides of the side plates first, and then weld the other set of diagonal sides. The above welding sequence can quickly form a stable basic frame structure and achieve a preliminary symmetrical balance between welding heat input and shrinkage stress on a macroscopic scale.

[0090] In one possible implementation, the first side plate 110 and the third side plate 130 are formed with filling grooves 150, and the cross-sectional width of the filling grooves 150 gradually increases from the bottom 152 to the opening 151. By directly forming the filling grooves 150 at the ends of multiple side plates, the process of separately beveling can be eliminated, which simplifies the manufacturing process and improves the material utilization rate.

[0091] The first side plate 110 and the third side plate 130 are welded and fixed by a ship-shaped welding method, including: forming a root layer 310 in the filling groove 150, and filling the bottom 152 of the filling groove 150 with the root layer 310; ensuring that the root of the filling groove 150 is fully melted, so as to provide basic positioning and structural strength for subsequent welding.

[0092] A cover layer 330 is formed by the bottom layer 310, and at least a portion of the cover layer 330 extends out of the groove 151 of the filler groove 150. This ensures a beautiful weld formation and uniform dimensions, and eliminates welding defects such as undercut, weld beads, and lack of fusion. The specific welding method is described in detail below through four embodiments.

[0093] Example 1: When the side plate thickness is ≤8 mm.

[0094] Please refer to Figure 3 In one possible implementation, the thickness of the first side plate 110 and the thickness of the third side plate 130 are less than or equal to 8 mm. Each side plate can first complete the welding of the base layer 310 according to the welding sequence of ACBD. Then, the weld seam between each side plate is welded with the cover layer 330 according to the welding sequence of ACBD, and the cover layer 330 is attached to the base layer 310.

[0095] Optionally, each weld seam can be continuously and uninterruptedly filled with a single filler weld. After completing the entire length of a single weld seam in one continuous pass, the diagonal welds are immediately welded sequentially using the same process parameters. Then, another set of diagonal welds is completed. This ensures that the welding heat input and shrinkage stress are structurally balanced symmetrically, further reducing overall welding deformation and improving the dimensional accuracy and structural stability of the box-type boom 100.

[0096] During welding, temperature monitoring can be performed between weld layers according to heat input control requirements to ensure that the interlayer temperature is controlled within a preset range. Each subsequent weld pass should fully cover the previous weld pass and achieve annealing. The above principles should be followed for each welding pass, and will not be elaborated further.

[0097] The above welding method reduces the number of welding layers and lowers the overall heat input while ensuring welding strength, effectively reducing welding shrinkage and deformation, and improving the dimensional accuracy and production efficiency of the box-type boom 100.

[0098] In one possible implementation, a root pass 310 is formed within the filler groove 150. During welding, the welding tip 410 of the welding torch 400 is kept perpendicular to the surface of the workpiece to be welded. Please refer to [reference needed]. Figure 2 .

[0099] For the 310 base layer, a small-amplitude serrated oscillating welding head 410 is used for welding, with an oscillation frequency of 2.5 Hz and an oscillation width of 2.5 mm. The middle transition is fast, and the sides are paused for 0.2 s. The welding speed is controlled at 20~35 cm / min.

[0100] The above-described embodiments can control the heat input of a single welding pass within a reasonable range, ensuring full penetration at the weld root while effectively suppressing initial deformation.

[0101] In one possible implementation, the cover layer 330 is welded using a serrated oscillating welding head 410 with an oscillation frequency of 2.5 Hz, an oscillation amplitude of 3 mm, an edge dwell time of 0.2 seconds, and a welding speed controlled at 30 cm / min.

[0102] By using the above process parameters, it is possible to ensure that the weld surface is flat and the contour is uniform, without appearance defects such as undercut and weld beads. While ensuring the quality of weld formation, it is also possible to effectively control the welding heat input and further suppress welding deformation.

[0103] For example, the welding current parameters for the 310 base coat are 160A~180A and the arc voltage parameters are 20V~22V, while the welding current parameters for the 330 cover coat are 210A~240A and the arc voltage parameters are 26V~29V.

[0104] In one possible implementation, when the thickness of the first side plate 110 and the thickness of the third side plate 130 are greater than 8 mm, a filler layer 320 is also formed between the base layer 310 and the top layer 330, and the filler layer 320 covers the base layer 310.

[0105] Optionally, the 320 filler layer welding employs a control strategy combining plate thickness layering, unit continuity, and system sequence to achieve precise coordinated control of welding heat input and structural deformation, ensuring stable and reliable welding quality and dimensional accuracy under different plate thickness conditions. Several specific embodiments are described below.

[0106] Example 2: When the side plate thickness is greater than 8 mm and less than or equal to 12 mm.

[0107] Please refer to Figure 4 Each side plate can first complete the welding of the root pass 310 according to the ACBD welding sequence, then complete the welding of the filler layer 320 according to the ACBD welding sequence, and finally weld the first cover layer 331 and the second cover layer 332 to the welds between each side plate according to the ACBD welding sequence. The filler layer 320 is bonded to the root pass 310, and the cover layer 330 is bonded to the filler layer 320.

[0108] When welding the bottom layer (310), keep the welding torch tip (410) perpendicular to the workpiece surface to be welded, and use a boat-shaped welding method with a small-amplitude serrated oscillating welding head (410). For the middle transition, proceed quickly, pausing for 0.2 seconds on both sides of the 150 groove opening (151), with an oscillation frequency of 2.5 Hz and an oscillation width of 2.5 mm. Control the welding speed at 20-35 cm / min, keeping the single-pass heat input within a reasonable range to ensure weld penetration while suppressing initial deformation of the component.

[0109] The filler layer 320 is welded using a small-amplitude serrated oscillating welding head 410, with an oscillation frequency of 2.5 Hz, an oscillation width of 4.5 mm, and a welding speed of 25~45 cm / min.

[0110] In this embodiment, the cover layer 330 is welded in two sequential passes. Each weld pass of the cover layer 330 employs a serrated oscillating welding technique, with the oscillation frequency strictly controlled at 2.5Hz and the oscillation amplitude set to 3mm. When the welding torch 400 oscillates to the edge of the serration, it needs to pause briefly for 0.2s to ensure good fusion at the weld edge and avoid incomplete fusion and undercut defects. The preferred welding speed is 30cm / min, and a uniform welding speed should be maintained. Upon completion of each weld pass and the arc ending, crater filling treatment is required to ensure a full and dent-free weld at the arc-ending area.

[0111] For example, the welding current parameters for the 310 base coat are 160A~180A, and the arc voltage parameters are 20V~22V; the welding current parameters for the 320 filler coat are 210A~240A, and the arc voltage parameters are 26V~29V; and the welding current parameters for the 330 cover coat are 210A~240A, and the arc voltage parameters are 26V~29V. Subsequent current or voltage parameters can be referenced from this embodiment and will not be repeated here.

[0112] Extensive experimental verification by the inventors has shown that the above-mentioned process parameters can stably control the heat input of a single pass, ensuring good fusion between the filler layer 320, the root pass 310, and the side walls, thus avoiding defects such as slag inclusions and incomplete fusion. The swing amplitude and welding speed provided in this application allow for uniform filling of the bevel layer by layer, ensuring weld density and structural strength. Simultaneously, precise control of heat accumulation suppresses interlayer deformation, providing a flat and uniform support surface for the subsequent welding of the cover layer 330, further improving the overall weld quality and dimensional accuracy.

[0113] Example 3: When the side plate thickness is greater than 12 mm and less than or equal to 14 mm.

[0114] Please refer to Figure 5 Each side plate can first complete the welding of the root pass 310 according to the welding sequence of ACBD. When welding the root pass 310, keep the welding tip 410 of the welding torch 400 perpendicular to the surface to be welded on the workpiece, and use a boat-shaped welding method and a small-amplitude sawtooth oscillation method. The middle transition is fast, and the two sides are paused for 0.2s. The oscillation frequency is 2.5Hz, the oscillation amplitude is 2.5mm, and the welding speed is controlled at 20~35cm / min. Control the heat input of a single pass within a certain range to ensure penetration while suppressing initial deformation.

[0115] The number of welding passes for filler layer 320 is adjusted to two. First, weld seam A is welded with the first filler layer 321 and the second filler layer 322. Then, weld seam C is welded with the first filler layer 321 and the second filler layer 322. Next, weld seam B is welded with the first filler layer 321 and the second filler layer 322. Finally, weld seam D is welded with the first filler layer 321 and the second filler layer 322.

[0116] The number of welding passes for the filler layer 320 was adjusted to two. The welding also adopted a sawtooth oscillation with a frequency of 2.5Hz and an amplitude of 4.2~4.5 mm, and stopped for 0.2 seconds on each side of the groove opening 151 of the filler groove 150 to ensure edge fusion.

[0117] Finally, the capping layer welding is performed. First, the first capping layer 331, the second capping layer 332, and the third capping layer 333 are welded onto weld A. Then, the first capping layer 331, the second capping layer 332, and the third capping layer 333 are welded onto weld C. Next, the first capping layer 331, the second capping layer 332, and the third capping layer 333 are welded onto weld B. Finally, the first capping layer 331, the second capping layer 332, and the third capping layer 333 are welded onto weld D.

[0118] The 330 cap coat welding needs to be performed in three passes sequentially. Each pass uses a zigzag oscillation method, with the oscillation frequency strictly controlled at 2.5Hz and the oscillation amplitude set to 3mm. When the welding torch 400 oscillates to the edge of the zigzag, it needs to pause briefly for 0.2 seconds to ensure good fusion at the weld edge and avoid incomplete fusion or undercut. The welding speed is preferably controlled at 30cm / min, maintaining a constant speed. After each pass, an arc crater filling operation is required to ensure a full and depression-free arc termination. For the welding process parameters of the 310 base coat, please refer to Example 1.

[0119] Example 4: When the side plate thickness is greater than 14 mm and less than or equal to 16 mm.

[0120] Please refer to Figure 6 Each side plate can first complete the welding of the bottom layer 310 according to the welding sequence of ACBD, then complete the welding of the first filler layer 321 according to the welding sequence of ACBD, and finally complete the welding of the second filler layer 322 and the third filler layer 323 according to the welding sequence of ACBD.

[0121] When welding the cover layer 330, the welding method is the same as in Example 3. First, weld the first cover layer 331, the second cover layer 332, and the third cover layer 333 on weld A, then weld the first cover layer 331, the second cover layer 332, and the third cover layer 333 on weld C. Then weld the first cover layer 331, the second cover layer 332, and the third cover layer 333 on weld B, and finally weld the first cover layer 331, the second cover layer 332, and the third cover layer 333 on weld D.

[0122] The filler layer 320 consists of three weld passes, which are applied in two layers respectively. The overall heat input is regulated by controlling the number of layers to match the plate thickness: the first filler layer 321 is a single-pass weld, while the second filler layer 322 and the third filler layer 323 consist of two parallel weld passes. When welding the filler layer 320, the welding torch 400 uses a sawtooth oscillation with a frequency of 2.5Hz and an amplitude of 4.2-4.5 mm, pausing for 0.2 seconds on each side of the bevel, at a welding speed of 25-45 cm / min. This ensures good edge fusion, while the continuous regional welding method ensures the stability of the heat input and shrinkage process of each weld seam. For the process parameters of the base layer 310 and the cover layer 330, please refer to Example 3.

[0123] The aforementioned sequential design allows the shrinkage stresses of spatially symmetrical welds to mutually restrain each other in a timely manner, while the continuous regional welding method ensures stable and reliable heat input and shrinkage processes for individual welds. By flexibly adjusting for different plate thicknesses, precise and coordinated control of welding heat input and structural deformation can be achieved.

[0124] This application establishes an scalable welding process system for box-type booms 100 with typical plate thicknesses of 8 mm, 12 mm, 14 mm, and 16 mm. The welding passes, layers, and parameters can be flexibly adjusted according to the plate thickness. The processes for the bottom layer (310), filler layer (320), and top layer (330) are optimized respectively, and a continuous one-piece welding is adopted to reduce the number of joints, ensure uniform weld quality and structural continuity, and avoid stress concentration.

[0125] Actual measurements show that the box-type boom 100 welded using the welding method described in this application exhibits excellent straightness and flatness control: the deviation within any 1-meter range is less than 1 millimeter, and the overall total deviation does not exceed 2 millimeters. The weld formation is aesthetically pleasing and uniform, with good fusion, and it has passed magnetic particle testing, fully meeting the welding quality requirements for high-strength steel structures.

[0126] The process described in this application can significantly suppress welding distortion, angular deformation, and longitudinal and transverse shrinkage while ensuring weld formation and internal mechanical properties. After adopting the process method provided in this application, key dimensional indicators such as straightness and flatness of the box-type boom meet the standards after welding, allowing for direct assembly without secondary straightening, reducing production costs, improving production efficiency and the first-pass yield of components, and enhancing structural load-bearing capacity and service reliability.

[0127] The welding control method in this application differs from traditional local improvement schemes that only target specific plate thicknesses or joint types. It can achieve systematic control of welding deformation at the overall structural level.

[0128] On the one hand, it breaks through the limitations of related technologies that only focus on the optimization of local welds or single slots. Through the coordinated control of the overall welding sequence, heat input distribution and stress release path, it effectively suppresses the macroscopic overall deformation of the box-type boom caused by the accumulation and mutual constraint of welding deformation of multiple components such as cover plate, web plate and partition, and significantly improves the structural dimensional accuracy and stability.

[0129] On the other hand, it is not limited to a single fixed plate thickness special process, but forms a coordinated control strategy applicable to working conditions where multiple plate thicknesses coexist in the same boom. While ensuring the welding quality of different plate thickness areas, it achieves balanced control of overall deformation, and has stronger versatility and engineering adaptability, thereby fundamentally overcoming the limitations of related technologies in controlling welding deformation of complex box-type booms.

[0130] In one possible implementation, the first side plate 110, the second side plate 120, the third side plate 130, and the fourth side plate 140 are pre-fixed by the retainer 200, including:

[0131] The first side plate 110, the second side plate 120, the third side plate 130, and the fourth side plate 140 are installed using tooling. The first side plate 110 and the second side plate 120 are positioned opposite each other, and the third side plate 130 and the fourth side plate 140 are positioned opposite each other. The retainer 200 is placed in the internal space formed by the multiple side plates, and the retainer 200 is tightly fitted to the inner wall of each side plate. Temporary fixation between the retainer 200 and each side plate is achieved by spot welding.

[0132] By pre-fixing the first side plate 110, the second side plate 120, the third side plate 130 and the fourth side plate 140 with the retainer 200, the side plates can be positioned before welding and form a stable box-shaped frame structure, ensuring that the relative positions of the side plates are accurate and the spacing is uniform.

[0133] The retainer 200 fits tightly against the inner walls of each side plate, significantly improving the overall rigidity of the structure during welding, effectively resisting lateral shrinkage and deformation caused by welding thermal stress, and improving the dimensional accuracy and structural stability of the box-type boom 100. After welding is completed, the retainer 200 and the box-type boom 100 can be removed.

[0134] By using the aforementioned welding method to prepare the box-shaped boom 100, the box-shaped boom 100 has technical effects such as small welding deformation, high structural strength, stable weld quality, and better finished product precision and reliability.

[0135] In one possible implementation, the box-type boom 100 includes a plurality of side plates, the plurality of side plates including a first side plate 110, a second side plate 120, a third side plate 130 and a fourth side plate 140;

[0136] A filling groove 150 is provided between two adjacent side plates. The cross-sectional width of the filling groove 150 gradually increases from the bottom 152 of the filling groove 150 to the opening 151 of the filling groove 150. This facilitates the gradual increase of the welding operation space, improves the quality of weld formation, and at the same time reduces welding stress concentration and reduces the risk of welding cracks.

[0137] The filling groove 150 is provided with a bottom layer 310, a filling layer 320 and a cover layer 330 stacked sequentially from the bottom 152 to the opening 151. The bottom layer 310 is located at the bottom of the filling groove 150 and is used to seal the filling groove 150 and provide basic positioning and structural strength for subsequent welding; ensuring the initial stability of the overall structure.

[0138] The rigidity of the filler layer 320 is higher than that of the base layer 310 and the cover layer 330, which can significantly improve the connection rigidity between adjacent side plates of the box boom 100 and enhance the overall load-bearing capacity of the box boom 100.

[0139] At least a portion of the cover layer 330 extends out of the groove 151. The cover layer 330 has a smooth surface, which can effectively cover and protect the weld inside the filling groove 150, and improve the appearance quality of the weld.

[0140] The overall structure of the box-type boom 100 is designed with layered functions, taking into account welding processability, structural strength and appearance quality, making the box-type boom 100 more reliable in welding, more uniform in stress distribution and longer in service life.

[0141] The box-type boom 100 provided in this embodiment is preferably made of Q690 high-strength welded structural steel for its side plates. It can perform the method provided in the above-mentioned method embodiment, and its implementation principle and technical effect are similar. This embodiment will not be described in detail here.

[0142] The box-type boom 100 and its welding method described in this application are highly systematic, and its deformation regulation and stress control ideas can provide a useful reference for the optimization of welding processes for other types of box-type structures.

[0143] Welding operations can be automated using welding robots. These robots include, but are not limited to, various types such as multi-degree-of-freedom industrial robots, collaborative robots, four-axis robots, gantry robots, and specialized customized welding robots. The brand and specific model are not limited. This invention does not impose specific limitations on the brand, model, or specific structural form of the welding robot, as long as it can achieve the predetermined welding trajectory and welding actions.

[0144] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0145] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0146] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0147] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A welding method for a box-type boom, characterized in that, include: The first side plate (110), the second side plate (120), the third side plate (130) and the fourth side plate (140) are pre-fixed by the retainer (200), so that the first side plate (110) is arranged opposite to the second side plate (120), and the third side plate (130) is arranged opposite to the fourth side plate (140); The first side plate (110) and the third side plate (130) are welded and fixed by a ship-shaped welding method, and the second side plate (120) and the fourth side plate (140) are welded and fixed by a ship-shaped welding method. The second side plate (120) and the third side plate (130) are welded and fixed by a ship-shaped welding method, and the first side plate (110) and the fourth side plate (140) are welded and fixed by a ship-shaped welding method.

2. The welding method for the box-type boom according to claim 1, characterized in that, The first side plate (110) and the third side plate (130) are formed with a filling groove (150), and the cross-sectional width of the filling groove (150) gradually increases from the bottom of the groove to the opening (151) of the groove. The first side plate (110) and the third side plate (130) are welded and fixed by a ship-shaped welding method, including: A base layer (310) is formed in the filling groove (150), and the base layer (310) fills the bottom of the filling groove (150); A cover layer (330) is formed on the base layer (310), at least a portion of which extends out of the slot (151) of the filling groove (150).

3. The welding method for the box-type boom according to claim 2, characterized in that, The thickness of the first side plate (110) and the thickness of the third side plate (130) are less than or equal to 8 mm, and the cover layer (330) is bonded to the base layer (310).

4. The welding method for the box-type boom according to claim 2, characterized in that, The underlayment (310) is formed in the filling groove (150). The underlayment (310) is welded using a small-amplitude serrated oscillating welding head (410) with an oscillation frequency of 2.5 Hz, an oscillation width of 2.5 mm, and a welding speed of 20~35 cm / min.

5. The welding method for the box-type boom according to claim 2, characterized in that, The cover layer (330) is welded using a small-amplitude sawtooth-shaped oscillating welding head (410), with an oscillation frequency of 2.5 Hz, an oscillation width of 3 mm, and a welding speed of 30 cm / min.

6. The welding method for the box-type boom according to claim 2, characterized in that, The thickness of the first side plate (110) and the thickness of the third side plate (130) are greater than 8 mm; Before the base layer (310) forms the cover layer (330), the welding method includes: A filler layer (320) is formed on the base layer (310), and the filler layer (320) covers the base layer (310).

7. The welding method for the box-type boom according to claim 6, characterized in that, The filler layer (320) is welded using a small-amplitude serrated oscillating welding head (410), with an oscillation frequency of 2.5 Hz, an oscillation width of 4.2~4.5 mm, and a welding speed of 25~45 cm / min.

8. The welding method for the box-type boom according to any one of claims 1-7, characterized in that, The first side plate (110), the second side plate (120), the third side plate (130), and the fourth side plate (140) are pre-fixed by a retainer (200), including: The first side plate (110), the second side plate (120), the third side plate (130) and the fourth side plate (140) are installed by tooling, with the first side plate (110) and the second side plate (120) arranged opposite to each other, and the third side plate (130) and the fourth side plate (140) arranged opposite to each other. The retainer (200) is disposed in the internal space formed by multiple side plates. The retainer (200) is tightly fitted to the inner wall of each of the multiple side plates, and the retainer (200) is temporarily fixed to each of the side plates by spot welding.

9. A box-type boom (100), characterized in that, It is formed by the welding method of the box-type boom (100) as described in any one of claims 1-8.

10. The box-type boom (100) according to claim 1, characterized in that, The box-type boom (100) includes multiple side plates, including a first side plate (110), a second side plate (120), a third side plate (130), and a fourth side plate (140); A filling groove (150) is provided between two adjacent side plates, and the cross-sectional width of the filling groove (150) gradually increases from the bottom of the groove (150) to the opening (151) of the groove (150). The filling groove (150) is provided with a base layer (310), a filling layer (320) and a cover layer (330) stacked sequentially from the bottom of the groove to the opening (151). The base layer (310) is located at the bottom of the filling groove (150) and is used to seal the filling groove (150) and provide basic positioning and structural strength for subsequent welding. The rigidity of the filler layer (320) is higher than that of the base layer (310) and the top layer (330). At least a portion of the cover layer (330) extends out of the slot (151), and the cover layer (330) has a smooth surface.

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