A complex box type cutting arm welding method of a digging-anchor integrated machine

Abstract

The application provides a complex box type cutting arm welding method of an integrated anchor machine, and belongs to the technical field of welding processes. The method comprises the following steps: the cutting arm box type structure is decomposed into a first component, a second component and a top plate, and is welded in groups; and the structure of the first component, especially the ear plate, is reinforced and welded. The advantages of the application are as follows: the component design facilitates segmented processing and quality control; the reinforced structure relationship and welding relationship are adopted at the hole matching position of the ear plate and the main rib plate, the structural strength of the weak point is ensured, and the optimized welding sequence is provided to control the welding deformation.

Description

Technical Field

[0001] This invention relates to the field of coal mine equipment manufacturing technology, and more specifically, to a welding method for a complex box-shaped cutting arm of a tunneling and anchoring integrated machine. Background Technology

[0002] The cutting arm is the core load-bearing component of the tunneling and anchoring machine. The component is made of Q690 high-strength steel and is welded together. It integrates a geared motor and undertakes key functions such as cutting and breaking rocks, load transmission and adjustment of working posture. The cutting arm is subjected to extreme loads such as alternating impact, cantilever bending moment and compound torsion for a long time. The working conditions are harsh, and its structural performance directly determines the reliability of the whole machine and the safety of underground operations.

[0003] The main body of the cutting arm consists of a large number of medium and thick plate fusion welding and ultra-thick plate pressing structures. Welding quality, thick plate welding deformation and residual stress control are the core factors affecting its strength, fatigue resistance and service life. Among them, the assembly sequence and welding process directly control the welding quality, welding deformation and residual stress. Moreover, the welding of high-strength steel thick plates is difficult and has a high risk of defects, which has become a key weakness restricting its long-term stable operation.

[0004] Structurally, the cutting arm is a closed box-shaped structure, formed by the combination of thick and ultra-thick plates. The overall structure is complex, the internal space is limited, and the cladding volume is large. Under the combined action of complex loads and welding residual stress in the application environment, fatigue cracking is likely to occur at the root of the arm body, the lug seat of the hydraulic cylinder, and other positions. At the same time, failures such as arm body bending, warping, and deformation of the hinge hole are also likely to occur.

[0005] In summary, the current welding solutions for cutting arms mainly address the following issues: ① Welding quality is difficult to guarantee: For thick and ultra-thick plates with large cladding volume welds, existing processes often use gas metal arc welding (MAG) with high heat input parameters to improve penetration and fusion efficiency. However, excessive heat input can lead to an increase in the width of the coarse grain zone in the heat-affected zone of the weld and severely coarse grains, resulting in a decrease in the low-temperature impact toughness and fracture resistance of the joint.

[0006] In addition, cold cracking is highly sensitive and is the most significant problem in the welding of 690MPa high-strength steel. Large heat input can cause the fracture mode to change from ductile fracture to cleavage fracture, increasing the risk of cold cracking and deformation.

[0007] In addition, excessive gaps caused by beveling and deformation can easily lead to internal defects such as incomplete root penetration, incomplete sidewall fusion, and slag inclusions during welding. This results in poor weld quality consistency, and internal defects become the main source of crack initiation for structural fatigue failure. Therefore, it is necessary to optimize and adjust the welding process to ensure the stability of the welding quality itself.

[0008] ② Severe Welding Deformation: The enclosed box-type structure has a complex weld space. Existing technology assembles all parts according to the drawings before continuous welding, and the internal structure of the box is complex with limited space. The entire assembly and welding process lacks sequential optimization based on the welding deformation patterns. The combined thermal shrinkage effects of multiple welds result in numerous weld defects in some components after welding, easily causing macroscopic deformations such as boom lateral bending, end face warping, and out-of-tolerance dimensions and positions of the hinge holes. Simultaneously, high residual stress concentrations occur at abrupt structural changes such as the boom root and cylinder lugs, significantly increasing the risk of weld cracking and failure when coupled with alternating service loads. Neither dimensional nor quality assurance can be achieved. Therefore, the welding sequence needs to be optimized based on the structural characteristics to avoid the impact of welding deformation.

[0009] ③ Weld fatigue life: During actual service, the cutting arm is subjected to intense random impact loads and periodic vibration stresses for extended periods. The geometric discontinuities of the weld joint (such as an excessively small toe transition radius) and the high tensile residual stress field superimpose each other, easily creating fatigue sources with high stress intensity factors in stress concentration areas such as the arm root and cylinder lugs. Under cyclic loading, cracks propagate rapidly, eventually leading to brittle fracture or impact fracture, severely restricting the equipment's service life and operational safety. Therefore, it is necessary to strengthen stress concentration areas in the structure to improve equipment safety and extend its service life.

[0010] In order to solve the above problems, people have been seeking an ideal technological solution. Summary of the Invention

[0011] The purpose of this invention is to address the shortcomings of existing technologies by providing a welding method for complex box-shaped cutting arms of tunneling and anchoring machines that ensures welding quality, avoids the impact of welding deformation by adjusting the welding sequence, and improves equipment safety and extends service life by targeted improvements to weak structural links.

[0012] To achieve the above objectives, the technical solution adopted by this invention is: a welding method for a complex box-shaped cutting arm of a tunneling and anchoring integrated machine, comprising the following steps: In the S1 design phase, the box-shaped structure is divided into a first component, a second component, and a top plate. The first component includes two parallel main stiffening plates, a side plate, two ear plates, and a supporting stiffening plate for connecting the two main stiffening plates. The ear plates have reinforcing blocks at the corresponding hinge holes, and corresponding reinforcing block mounting holes are provided at the corresponding positions of the main stiffening plates. The second component includes the remaining parts excluding the top plate. S2 parts are cut and blanked, and the plates are beveled. S3 First Component Welding: S31 assembles the mounting plate and ear plate onto the main stiffening plate to construct two main stiffening components, welds the bevel welds between the main stiffening plate and the mounting plate, and performs local preheating before welding to complete the preparation of the two main stiffening components. S32 marks lines on the assembly platform to assemble two main rib components and two support ribs, ensuring that there is an assembly gap between each support rib and the two main ribs and that the gap width is symmetrical based on the center plane. S33 performs front and back root welding on the two supporting stiffeners and the main stiffener respectively, and then performs filling and cover welding on the two supporting stiffeners and the main stiffener symmetrically; then welds the reinforcing blocks of the two ear plates and the reinforcing block mounting holes of the main stiffener symmetrically, and finally welds the main stiffener symmetrically on the outer contour of the ear plate. After the S34 welding is completed, each weld in the first component is subjected to flaw detection. S4 performs welding on the main frame of the second component and completes the connection and welding with the first component. After welding, flaw detection is performed on each weld. S5 is based on the second component to weld the top plate, then weld the remaining welds between the first and second components, as well as the welds of the end stiffeners of the second component. After the welding is completed, the welds are inspected for flaws. Finally, the welds between the supporting stiffeners and the bottom and top plates are completed, thus completing the welding work of the cutting arm components. After S6 welding, the cutting arm component undergoes stress-relief annealing.

[0013] This invention addresses the box-shaped structure of the cutting arm by dividing it into two components and a top plate. These components are welded separately and in segments according to their form. For the first component, the main rib components are pre-embedded, followed by the welding of the internal key rib welds, and finally, the symmetrical welding of the external welds. This ensures welding quality and reduces welding deformation. For the weak point of the ear plate, the structural form and welding process are uniformly optimized. The connection structure at the ear plate hinge hole is strengthened, and the ear plate is pre-welded to the main rib, ensuring symmetrical ear plate positioning and uniform stress distribution. This further ensures stable assembly gaps between the ear plate and the main rib plate, guaranteeing complete penetration of the outer weld root and ensuring coordinated load-bearing under alternating loads. This significantly improves the fatigue life of the joint.

[0014] Based on the above, the second component includes a partition, a bottom plate, two outer stiffening plates, two inner stiffening plates, two support seats, an end stiffening plate, and two connecting stiffening plates; The specific process of step S4 is as follows: S41 marks and assembles two inner stiffening plates on the base plate. When assembling the inner stiffening plates, a reverse deformation angle is reserved. Then, the welds between the inner stiffening plates and the base plate are symmetrically welded so that the dimensions required by the drawing can be obtained by utilizing the welding deformation after the bevel welding. S42 assembled support base, welded support base to the inner stiffening plate and the bottom plate; S43 assembles the end stiffeners, two outer stiffeners, two connecting stiffeners and the first component. After welding the welds between the two connecting stiffeners and the bottom plate, the partition is assembled. S44 segmented, symmetrically welded welds between two inner stiffening plates and adjacent supporting stiffening plates, vertical welds between the bottom plate and outer stiffening plates located inside the box-shaped structure, and welds between the partition plate and two supporting stiffening plates. After the S45 welding is completed, the welds of the outer stiffening plate, bottom plate, inner stiffening plate, and partition are subjected to flaw detection.

[0015] Based on the above, the specific process of step S5 is as follows: S51 Symmetrical welding of all welds on the bottom plate, top plate, main stiffening plate, and outer stiffening plate; S52 Welding: All welds between the main rib assembly and the outer rib plate, inner rib plate and end rib plate; After the S53 welding is completed, flaw detection is performed on each weld seam. S54 welds between the base plate, top plate, and supporting stiffeners.

[0016] During this process, symmetrical welding of the external main weld seams is carried out. Through the mutual cancellation of weld shrinkage, macroscopic deformations such as arm body lateral bending and end face warping are effectively reduced, ensuring the dimensional and positional accuracy of the hinge holes and mounting mating surfaces, and meeting the precision assembly requirements of the whole machine. At the same time, the segmented back welding and layered staggered welding method can avoid local heat concentration, making the temperature field distribution of the structure more uniform, significantly reducing the peak value of residual tensile stress in the weld seams, weakening the stress concentration effect in key areas such as the arm body root and cylinder lugs, and reducing the risk of coupling failure between residual stress and working load.

[0017] Based on the above, all welds are flat welds. Among them, the vertical welds between the two supporting stiffeners and the main stiffener and the vertical welds between the bottom plate and the outer stiffener are K-type full penetration welds. Except for the bevel welds of the ear plates and the support seats, the remaining bevel welds are full penetration welds.

[0018] Based on the above, all welds were performed in the order of root pass, fill pass, and cover pass. The root pass was performed using single-wire welding, while the fill pass and cover pass were performed using double-wire welding. The welding mode was cold metal transfer + pulse.

[0019] Based on the above, during the filler welding process, the front wire is the main wire, with a higher current and voltage than the rear wire, and the peak pulse current of the front wire is also higher; the rear wire is the auxiliary wire, used to supplement the filler metal and control the overall heat input.

[0020] Welding employs a root pass + filler / cap coat technique. The root pass uses a single-wire cold metal transfer (CMT) + pulse (P) method, while the filler and cap coat use twin-wire welding, both in a CMT + P pattern. This precise control of the welding heat input range, combined with the pulse process, ensures penetration depth and sidewall fusion quality, preventing excessive growth of the coarse grain zone in the heat-affected zone caused by high heat input. This effectively improves the joint microstructure and enhances the low-temperature impact toughness and fracture resistance of the weld and heat-affected zone. Simultaneously, the interpass tempering effect of multi-layer, multi-pass welding further refines the weld microstructure. Combined with precise control of interpass temperature, this effectively avoids the risk of cold cracking in high-strength steel welding, comprehensively improving the overall mechanical properties of thick plate welded joints and ensuring 100% ultrasonic testing qualification of the weld.

[0021] Based on the above, in S2, the bevel angle is 45° and the bevel blunt edge is ≤1mm.

[0022] Based on the above, in S32, the assembly gap between each connecting stiffener and the two main stiffeners is 1.5-2mm.

[0023] Based on the above, it also includes a weld surface defect detection system, which includes: A multi-axis robot, in conjunction with a laser positioning and vision recognition system, positions and identifies the dimensions of the welded box-shaped cutting arm. The data processing center is used to reconstruct three-dimensional models from the identified data, decompose the base and weld, and generate independent three-dimensional models of the weld. The intelligent analysis system locates and performs high-precision scanning on the generated 3D model of the weld, obtains the surface defect parameters of the weld, marks and locates welds with surface defects, and sends the analysis results to the terminal for staff to make corrections.

[0024] This invention has outstanding substantive features and significant progress compared to the prior art. Specifically, this invention has the following advantages: 1. The complete cutting arm box structure is optimized into two components and a top plate during the manufacturing stage. The first component with the ear plate is welded first, and then the second component is welded. The welding of the second component with the first component is completed during the welding process. The welding quality is ensured and welding deformation is reduced by the group welding scheme.

[0025] 2. The ear plate is optimized separately. The optimization of the ear plate structure itself lies in the addition of reinforcing blocks. In the welding process, the combination of reinforcing blocks and main stiffening plates ensures the welding and positioning accuracy of the ear plate on the one hand, and forms two welds with the outer contour weld of the ear plate on the other hand, which strengthens the ear plate's own structure and welding structure, ensures the symmetry of the left and right ear plates and the welding quality, and improves fatigue life under complex alternating loads.

[0026] 3. The overall welding process of the first and second components has been optimized. First, the main rib components are pre-embedded, then the internal key rib plate welds are assembled and welded, and then the external main welds are symmetrically welded. Through the mutual cancellation of weld shrinkage, macroscopic deformations such as boom lateral bending and end face warping are effectively reduced, ensuring the dimensional and positional accuracy of the hinge holes and installation mating surfaces, and meeting the precision assembly requirements of the whole machine. At the same time, the segmented back welding and layered staggered welding method can avoid local heat concentration, making the temperature field distribution of the structure more uniform, significantly reducing the peak value of residual tensile stress in the weld, weakening the stress concentration effect in key areas such as the boom root and cylinder lugs, and reducing the risk of coupling failure between residual stress and working load.

[0027] 4. Innovations were made in welding parameters and specific processes, proposing single-wire CMT+P for root pass and double-wire CMT+P for filler and cover pass. This ensures both high weld quality and high efficiency in filler and cover passes. Furthermore, the combination of these parameters guarantees the comprehensive mechanical properties of the welded weld. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the complex box-shaped cutting arm of the tunneling and anchoring integrated machine in this invention.

[0029] Figure 2 This is a schematic diagram of the structure of the first component in this invention.

[0030] Figure 3 This is a comparison of the structural diagrams of the ear plate before and after the improvement in this invention.

[0031] Figure 4 This is a structural schematic diagram of the main rib component in this invention.

[0032] Figure 5 This is a schematic diagram of the assembly of the first and second components in this invention.

[0033] Figure 6 This is a schematic diagram of the welding state of the double welding wire in this invention.

[0034] Figure 7 This is a schematic diagram showing the location of the weld surface defect detection system in this invention.

[0035] In the diagram: 100. First component; 200. Second component; 300. Top plate; 400. Assembly platform; 500. Weld surface defect detection system; 101. Main stiffener plate; 102. Adhesive plate; 103. Ear plate; 104. First support stiffener plate; 105. Second support stiffener plate; 1031. Reinforcing block; 201. Partition plate; 202. Bottom plate; 203. Outer stiffener plate; 204. Inner stiffener plate; 205. Support base; 206. End stiffener plate; 207. Connecting stiffener plate. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0037] like Figures 1-6 As shown, a welding method for a complex box-shaped cutting arm of a tunneling and anchoring integrated machine includes the following steps: In the S1 design phase, the box-shaped structure is divided into the first component 100, the second component 200, and the top plate 300.

[0038] The first component 100 includes two parallel main stiffening plates 101, a backing plate 102, two ear plates 103, and supporting stiffening plates for connecting the two main stiffening plates 101, namely a first supporting stiffening plate 104 and a second supporting stiffening plate 105. The ear plates 103 have reinforcing blocks 1031 at the corresponding hinge holes on their assembly surfaces, and corresponding reinforcing block mounting holes are provided on the main stiffening plates 101 at corresponding positions to enhance the connection strength. A comparison of the ear plates 103 before and after optimization is shown below. Figure 3 As shown.

[0039] The existing technology involves directly assembling the ear plates onto the surface of the main rib. Due to material cutting, beveling deformation, and accumulated assembly errors, the asymmetry of the left and right ear plates leads to unbalanced stress on the cutting arm and premature failure. At the same time, the misalignment of the pin holes accelerates the wear and leakage of the seals, and in severe cases, it can even cause the hydraulic cylinder to become stuck or jammed.

[0040] This invention optimizes the structure of the ear plate and the main stiffening plate without affecting the structural strength. The ear plate and the main stiffening plate are pre-embedded and welded together to ensure that the ear plate is symmetrically positioned and evenly stressed. At the same time, it further ensures that the assembly gap between the ear plate and the main stiffening plate is ≤0.5mm, ensuring that the root of the outer weld is completely fused and that the joint can bear loads together under stress. Under alternating load conditions, it can significantly improve the fatigue life of the joint.

[0041] In terms of position, the two main stiffening plates 101 are parallel to each other. The first supporting stiffening plate 104 is connected to the front end between the two main stiffening plates 101, and the second supporting stiffening plate 105 is connected to the rear end between the main stiffening plates 101 to form a box-shaped structure. The side plate 102 is located on the outside of the main stiffening plate 101 and close to the front end, and the ear plate 103 is located on the outside of the main stiffening plate 101 and close to the rear end.

[0042] The second component 200 includes a partition 201, a base plate 202, two outer stiffening plates 203, two inner stiffening plates 204, two support bases 205, an end stiffening plate 206, and two connecting stiffening plates 207.

[0043] In terms of specific structural relationships, the front ends of the two outer stiffening plates 203 are fixed to the outer side of the rear end of the main stiffening plate 101, the front ends of the two inner stiffening plates 204 are fixed to the inner side of the rear end of the main stiffening plate 101, the rear ends of the two outer stiffening plates 203 and the two inner stiffening plates 204 are both fixed to the front side of the end stiffening plate 206, and the bottom plate 202 is installed between the two inner stiffening plates 204, with its front end connected to the second supporting stiffening plate 105 and its rear end connected to the end stiffening plate 206. The two support seats 205 are located inside the two inner stiffening plates 204 and are symmetrically arranged, and are also fixed to the base plate 202; The two connecting stiffeners 207 are parallel to each other, and their front and rear ends are fixed to the first supporting stiffener 104 and the second supporting stiffener 105 respectively. A partition 201 is provided in the enclosed area between the two connecting stiffeners 207, the first supporting stiffener 104 and the second supporting stiffener 105.

[0044] The top plate 300 covers the top of the first component 100 and the second component 200 after they are welded together.

[0045] The above describes the complete structural form of the entire cutting arm box structure and the distribution of its component structures. The specific manufacturing process is as follows: S2 parts cutting and blanking: The cutting machine is used to cut the sheet metal, including the main stiffening plate, cover plate and stiffening plate; the cutting machine is used to cut the bevel of the sheet metal, the bevel angle is 45° and the bevel blunt edge is guaranteed to be ≤1mm. S3 First Component Welding: S31 The mounting plate 102 and ear plate 103 are respectively assembled onto the main stiffening plate 101 to construct two main stiffening components. The bevel weld between the main stiffening plate 101 and the mounting plate 102 is welded. In order to reduce the overall welding stress and prevent the welding deformation after the main stiffening plate 101 is pre-embedded, which will cause the assembly size error to increase, the external weld is not welded first. Local preheating is used before welding, and the preheating temperature is 120-150℃.

[0046] S32 marks and assembles two main rib components and the first support rib plate 104 and the second support rib plate 105 on the assembly platform 400. It is necessary to ensure that the assembly gap between the first support rib plate 104, the second support rib plate 105 and the main rib plate 101 is 1.5-2mm, and that the left and right sides are symmetrical with the center face.

[0047] S33 performs front and back root welding on the first support stiffener 104, the second support stiffener 105 and the main stiffener 101 respectively. After the root welding, filler and cover welds are symmetrically welded between the first support stiffener 104, the second support stiffener 105 and the main stiffener 101. Then, the welds of the reinforcing blocks 1031 of the two ear plates 103 and the reinforcing block mounting holes of the main stiffener 101 are symmetrically welded. Finally, the welds of the main stiffener 101 and the outer contour of the ear plate 103 are symmetrically welded. Its advantage is that the welding relationship at the reinforcing block 1031 can provide sufficient structural strength for the ear plate 103. Combined with the weld at the outer contour, two welds are formed, and the connection structure is more solid. The ear plate 103 is also a concentrated stress area. After optimizing the structure, the stability and durability of the overall structure can be guaranteed, and the service life can be improved.

[0048] After the S34 welding is completed, 100% ultrasonic testing is performed on each weld in the first component 100. If the testing results are qualified, the subsequent steps are continued.

[0049] S4 performs welding on the main frame of the second component 200 and completes the connection and welding with the first component 100. After welding, flaw detection is performed on each weld.

[0050] The specific process is as follows: S41 marks and assembles two inner stiffening plates 204 on the base plate 202. The inner stiffening plates 204 are reserved with a reverse deformation angle during assembly. After the bevel welding, the shrinkage due to welding deformation will finally obtain the dimensions and angle required by the drawing.

[0051] Specifically, the welds between the inner stiffening plate 204 and the base plate 202 are symmetrically welded to build the main frame structure, provide the structural foundation, and prevent deformation.

[0052] The S42 assembly support 205 is assembled, and the weld between the support 205 and the inner stiffening plate 204 and the base plate 202 is welded to complete the welding and fixing of the key component support 205 and ensure its structural accuracy.

[0053] S43 assembles the end stiffener 206, two outer stiffeners 203, two connecting stiffeners 207 and the first component 100, and welds the two connecting stiffeners 207 to the bottom plate 202, then assembles the partition 201.

[0054] The welds of the two inner stiffening plates 204 and the second supporting stiffening plate 105 are segmented and symmetrically welded in S44; the vertical welds of the bottom plate 202 and the outer stiffening plate 203 located inside the box shape are welded; and the welds of the partition plate 201 with the first supporting stiffening plate 104 and the second supporting stiffening plate 105 are welded.

[0055] After the S45 welding is completed, the welds of the outer stiffening plate 203, the bottom plate 202, the inner stiffening plate 204, and the partition plate 201 are subjected to 100% ultrasonic testing. After the testing results are qualified, the subsequent steps are continued.

[0056] S5 is based on the second component 200 to weld the top plate 300, and symmetrically weld all the welds of the bottom plate 202, the top plate 300 to the main stiffening plate 101, and the outer stiffening plate 203. Then weld the welds of the main stiffening component to the outer stiffening plate 203, and the outer stiffening plate 203 to the end stiffening plate 206. After welding, 100% ultrasonic testing is performed. After the testing result is qualified, the subsequent steps are performed.

[0057] Weld the bottom plate 202, the top plate 300 and the first support stiffener 104.

[0058] After S6 welding, the cutting arm component undergoes stress-relief annealing.

[0059] The above-mentioned welding sequence is designed to address the weld distribution characteristics of the enclosed box-type structure. To ensure welding quality and reduce welding deformation, the box-type structure is divided into two parts: first, the main rib components are pre-embedded; then, the internal key rib welds are assembled and welded; and finally, the external main welds are symmetrically welded. Through the mutual cancellation of weld shrinkage, macroscopic deformations such as boom lateral bending and end face warping are effectively reduced, ensuring the dimensional accuracy of the hinge holes and mounting mating surfaces, and meeting the precision assembly requirements of the entire machine. At the same time, the segmented back-welding and layered staggered welding method can avoid local heat concentration, making the structural temperature field distribution more uniform, significantly reducing the peak value of residual tensile stress in the weld, weakening the stress concentration effect in key areas such as the boom root and cylinder lugs, and reducing the risk of coupling failure between residual stress and working load.

[0060] The welding process parameters are as follows: 1.4mm diameter solid wire, shielding gas Ar+20%CO2, shielding gas flow rate 15-20L / min, preheating in a box-type resistance furnace before welding, preheating temperature 120-150℃, and all welds are flat welds. Among them: K-type full penetration welds: the vertical welds on both sides of the first supporting stiffener 104 and the second supporting stiffener 105, and the vertical welds between the bottom plate 202 and the outer stiffener 203.

[0061] Except for the bevel welds of ear plate 103 and support seat 205, all other bevel welds are full penetration welds.

[0062] The welding equipment used is the Fronius TPS5000 welding machine, and the automated welding equipment is an ABB six-axis robot.

[0063] All welds were performed in the sequence of root pass, fill pass, and cover pass, with the parameters set as follows: Root pass welding: Single-wire welding is used, with a welding mode of cold metal transfer (CMT) + pulse (P). Current is 180-210A, voltage is 20-23V, wire feed speed is 7-10m / min, welding speed is 30-35cm / min, and wire extension is 15mm. The single-wire cold metal transfer combined with the pulse mode ensures low overall heat input to the weld, preventing cold cracking, especially delayed cracking, during cooling due to excessive heat input. The addition of the pulse mode increases weld penetration, ensuring complete weld penetration and good back-side formation.

[0064] Filler Parameters: Twin-wire welding is used, with a welding mode of Cold Metal Transfer (CMT) + Pulse (P). The front wire current is 180-220A, voltage is 22-25V, wire feed speed is 10-14m / min, welding speed is 40-45cm / min, and wire extension is 15mm. The rear wire current is 140-160A, voltage is 19-22V, wire feed speed is 8-10m / min, and wire extension is 15-18mm. During welding, the front wire is the primary wire, with higher current and voltage than the rear wire, and a higher pulse peak current (IP) to ensure root and sidewall fusion. The rear wire is the auxiliary wire, mainly responsible for supplementing filler metal and controlling overall heat input. Its function is as follows: Figure 6 As shown.

[0065] The alternating pulse and short-circuit transitions between the front and rear wires further reduce overall heat input. The short high-temperature dwell time and narrow heat-affected zone minimize grain coarsening in the Q690 heat-affected zone, resulting in greater weld penetration. Throughout the welding process, spatter is minimal, and the weld bead is smooth.

[0066] Cover parameters: Twin-wire welding is used, welding mode is cold metal transfer (CMT) + pulse (P), front wire current 160-200A, voltage 21-24V, wire feed speed 8-10m / min, welding speed 45-50cm / min, welding wire extension 15mm; rear wire current 140-150A, voltage 19-22V, wire feed speed 6-8m / min, welding wire extension 15-18mm.

[0067] The entire welding process employs a root pass + fill and cover pass method. The root pass uses a single-wire cold metal transfer (CMT) + pulse (P) technique, while the fill and cover passes use twin-wire welding, with both welding modes being CMT + P. Precise control of the welding heat input range, combined with the pulse process, ensures penetration depth and sidewall fusion quality, avoiding excessive growth of the coarse-grained zone in the heat-affected zone caused by high heat input. This effectively improves the joint microstructure and enhances the low-temperature impact toughness and fracture resistance of the weld and heat-affected zone. Simultaneously, the interpass tempering effect of multi-layer, multi-pass welding further refines the weld microstructure. Combined with precise control of interpass temperature, this effectively mitigates the risk of cold cracking in high-strength steel welding, comprehensively improving the overall mechanical properties of thick plate welded joints and ensuring 100% ultrasonic testing qualification of the weld.

[0068] like Figure 7 As shown, in a preferred embodiment, the system further includes a weld surface defect detection system 500, which includes: A multi-axis robot, in conjunction with a laser positioning and vision recognition system, positions and identifies the dimensions of the welded box-shaped cutting arm. In this embodiment, a six-axis ABB robot is used. Through the laser positioning and vision recognition system mounted at the front end, it can quickly and intelligently position the workpiece on the operating table and identify the workpiece's dimensional parameters, including length, width, height, weight, and structure.

[0069] The data processing center is used to reconstruct 3D models from the identified data, decompose the base and weld, and generate independent 3D models of the weld.

[0070] The intelligent analysis system locates the 3D weld model picked up by the data processing center, uses low-speed, high-precision scanning to measure the weld reinforcement height, identify and analyze the wetting angle α between the weld and the base material, and identify and extract welding surface defects such as porosity, depressions, undercut, and cracks. Welds with surface defects, insufficient reinforcement height, or wetting angle α ≤ 110° are marked and located. The analysis results are stored and transmitted back to the terminal of the on-site operator. Based on the results, the problematic welds are ground, repaired, or treated with TIG melting.

[0071] After the above defects are manually processed, the processed defective welds are scanned and analyzed a second time. If there are no defects, the welds are released; if there are defects, the data is uploaded and reprocessed until there are no defects.

[0072] This preferred solution uses laser positioning and visual scanning analysis to accurately and efficiently identify surface defects in welds, and can provide closed-loop prompts until the inspection is passed.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A welding method for a complex box-shaped cutting arm of a tunneling and anchoring integrated machine, characterized in that, Includes the following steps: In the S1 design phase, the box-shaped structure is divided into a first component, a second component, and a top plate. The first component includes two parallel main stiffening plates, a side plate, two ear plates, and a supporting stiffening plate for connecting the two main stiffening plates. The ear plates have reinforcing blocks at the corresponding hinge holes, and corresponding reinforcing block mounting holes are provided at the corresponding positions of the main stiffening plates. The second component includes the remaining parts excluding the top plate. S2 parts are cut and blanked, and the plates are beveled. S3 First Component Welding: S31 assembles the mounting plate and ear plate onto the main stiffening plate to construct two main stiffening components, welds the bevel welds between the main stiffening plate and the mounting plate, and performs local preheating before welding to complete the preparation of the two main stiffening components. S32 marks lines on the assembly platform to assemble two main rib components and two support ribs, ensuring that there is an assembly gap between each support rib and the two main ribs and that the gap width is symmetrical based on the center plane. S33 performs front and back root welding on the two supporting stiffeners and the main stiffener respectively, and then performs filling and cover welding on the two supporting stiffeners and the main stiffener symmetrically; then welds the reinforcing blocks of the two ear plates and the reinforcing block mounting holes of the main stiffener symmetrically, and finally welds the main stiffener symmetrically on the outer contour of the ear plate. After the S34 welding is completed, each weld in the first component is subjected to flaw detection. S4 performs welding on the main frame of the second component and completes the connection and welding with the first component. After welding, flaw detection is performed on each weld. S5 is based on the second component to weld the top plate, then weld the remaining welds between the first and second components, as well as the welds of the end stiffeners of the second component. After the welding is completed, the welds are inspected for flaws. Finally, the welds between the supporting stiffeners and the bottom and top plates are completed, thus completing the welding work of the cutting arm components. After S6 welding, the cutting arm component undergoes stress-relief annealing.

2. The welding method for the complex box-shaped cutting arm of the tunneling and anchoring integrated machine according to claim 1, characterized in that, The second component includes a partition, a bottom plate, two outer stiffening plates, two inner stiffening plates, two support bases, an end stiffening plate, and two connecting stiffening plates; The specific process of step S4 is as follows: S41 marks and assembles two inner stiffening plates on the base plate. When assembling the inner stiffening plates, a reverse deformation angle is reserved. Then, the welds between the inner stiffening plates and the base plate are symmetrically welded so that the dimensions required by the drawing can be obtained by utilizing the welding deformation after the bevel welding. S42 assembled support base, welded support base to the inner stiffening plate and the bottom plate; S43 assembles the end stiffeners, two outer stiffeners, two connecting stiffeners and the first component. After welding the welds between the two connecting stiffeners and the bottom plate, the partition is assembled. S44 segmented, symmetrically welded welds between two inner stiffening plates and adjacent supporting stiffening plates, vertical welds between the bottom plate and outer stiffening plates located inside the box-shaped structure, and welds between the partition plate and two supporting stiffening plates. After the S45 welding is completed, the welds of the outer stiffening plate, bottom plate, inner stiffening plate, and partition are subjected to flaw detection.

3. The welding method for the complex box-shaped cutting arm of the tunneling and anchoring integrated machine according to claim 2, characterized in that, The specific process of step S5 is as follows: S51 Symmetrical welding of all welds on the bottom plate, top plate, main stiffening plate, and outer stiffening plate; S52 Welding: All welds between the main rib assembly and the outer rib plate, inner rib plate and end rib plate; After the S53 welding is completed, flaw detection is performed on each weld seam. S54 welds between the base plate, top plate, and supporting stiffeners.

4. The welding method for the complex box-shaped cutting arm of the tunneling and anchoring integrated machine according to any one of claims 1-3, characterized in that, All welds are flat welds. Among them, the vertical welds between the two supporting stiffeners and the main stiffener and the vertical welds between the bottom plate and the outer stiffener are K-type full penetration welds. Except for the bevel welds of the ear plates and the support seats, the remaining bevel welds are full penetration welds.

5. The welding method for the complex box-shaped cutting arm of the tunneling and anchoring integrated machine according to any one of claims 1-3, characterized in that, All welds were performed in the order of root pass, fill pass, and cover pass. The root pass was performed using single-wire welding, while the fill pass and cover pass were performed using double-wire welding. The welding mode was cold metal transfer + pulse.

6. The welding method for the complex box-shaped cutting arm of the tunneling and anchoring integrated machine according to claim 5, characterized in that, During the filler welding process, the front wire is the main wire, with a higher current and voltage than the rear wire, and the pulse peak current of the front wire is also higher; the rear wire is the auxiliary wire, used to supplement filler metal and control the overall heat input.

7. The welding method for the complex box-shaped cutting arm of the tunneling and anchoring integrated machine according to claim 1, characterized in that, In S2, the bevel angle is 45° and the bevel blunt edge is ≤1mm.

8. The welding method for the complex box-shaped cutting arm of the tunneling and anchoring integrated machine according to claim 1, characterized in that, In S32, the assembly gap between each connecting stiffener and the two main stiffeners is 1.5-2mm.

9. The welding method for the complex box-shaped cutting arm of the tunneling and anchoring integrated machine according to claim 1, characterized in that, It also includes a weld surface defect detection system, which comprises: A multi-axis robot, in conjunction with a laser positioning and vision recognition system, positions and identifies the dimensions of the welded box-shaped cutting arm. The data processing center is used to reconstruct three-dimensional models from the identified data, decompose the base and weld, and generate independent three-dimensional models of the weld. The intelligent analysis system locates and performs high-precision scanning on the generated 3D model of the weld, obtains the surface defect parameters of the weld, marks and locates welds with surface defects, and sends the analysis results to the terminal for staff to make corrections.

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