Transition structure of thick plate butt weld, welding process and engineering machinery
By designing the transition structure and welding process for butt welds of thick plates, the problems of uneven weld filling and poor sidewall fusion during butt welding of thick plates were solved, achieving stability of weld quality and smooth transition of structure, which is suitable for heavy-load and vibration conditions of mining machinery.
Patent Information
- Application Number
- CN202511759729.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-01-09
AI Technical Summary
In the manufacturing of large mining machinery, the inconsistent thickness and groove angles of thick plates during butt welding lead to welding defects such as uneven weld filling, poor sidewall fusion, and stress concentration, making it difficult to meet the long-term service requirements under heavy loads and harsh working conditions.
A transition structure for butt welds in thick plates is designed, including a bevel region and a transition region. By setting parameters such as bevel angle, depth, and length, a smooth transition between the bevel and non-bevel structures is achieved. Layered welding and posture control welding processes are adopted to ensure weld quality.
It achieves uniform weld filling and smooth weld transition, reduces the risk of welding defects, improves welding quality and structural stability, and meets the requirements of heavy-load and vibration conditions of mining machinery.
Smart Images
Figure CN121289846A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a transition structure and welding process for butt welds of thick plates, as well as engineering machinery, belonging to the field of mining machinery. Background Technology
[0002] In the manufacturing process of large mining machinery (such as crusher frames, mining conveyor housings, and tunneling machine main structures), the butt joint connection of thick plates (usually 20-50mm thick) is a core process. Bevel butt welding has become the mainstream process choice in the industry because it can ensure the strength of the joint.
[0003] However, in actual production scenarios, due to the influence of component design requirements and differences in plate procurement specifications, the two butt joint steel plates often have inconsistent thicknesses and inconsistent bevel angles / forms, resulting in significant technical bottlenecks in existing welding processes: On the one hand, the connection between the bevel and non-bevel areas is abrupt, and the welding torch oscillation trajectory cannot achieve a smooth transition, which in turn causes uneven distribution of weld filler, with some areas being overfilled and others underfilled, directly affecting the appearance of the weld; on the other hand, the sidewall fusion depth is difficult to control precisely, which easily leads to welding defects such as incomplete fusion, slag inclusions, and porosity, and the irregular weld shape can cause stress concentration, reduce the fatigue strength of the joint, and ultimately lead to poor welding quality stability, making it difficult to meet the long-term service requirements of large mining machinery under heavy loads, vibrations, and harsh working conditions, and even posing safety hazards. Summary of the Invention
[0004] To address the problems existing in the prior art, the present invention provides a transition structure and welding process for butt welds of thick plates, as well as engineering machinery, to achieve uniform weld bead filling, smooth weld transition, and improve sidewall fusion effect, thereby improving welding quality.
[0005] To achieve the above objectives, the present invention employs a transition structure for butt welds of thick plates, used for butt welding of thick plates in mining machinery, wherein the thickness t of the thick plate is 20-50mm. The transition structure is provided at the end of the thick plate along the butt joint direction of the thick plate, and includes a bevel area and a transition area connected in sequence. The end face parameter of the bevel region is β×D, where β is the bevel angle and D is the bevel depth, and the length of the bevel region is L1; the transition region is an extension structure of the bevel region, with the β×D section of the bevel region as the starting surface and the non-bevel end of the thick plate as the ending surface, and the length of the transition region is L2. The smooth transition between the bevel and non-bevel structures is achieved through the transition region. The bevel angle β is 20°-45°, the bevel depth D is 10-32mm, the length L1 is 50-150mm, and the length L2 is 50-200mm.
[0006] As an improvement, a rounded corner is provided at the junction of the bevel area and the transition area to form a smooth transition, and the radius of the rounded corner is 80mm-120mm.
[0007] As an improvement, the transition structure is suitable for box-type welded assemblies of mining machinery; The box-type welding assembly includes a cover plate, side plate I and side plate II. The transition structure is machined on the end side of the cover plate, and the bevel region parameter β×D of the transition structure is consistent with the single-sided V-shaped bevel parameter opened on side plate I and side plate II to achieve docking adaptation.
[0008] As an improvement, the transition structure is suitable for steel pipe welding assemblies in mining machinery; The steel pipe welding assembly includes a cover plate, a side plate III, and a steel pipe. One end of the cover plate has a bent arc structure, and the transition structure is machined on the side of the bent arc end of the cover plate. In the transition structure, the length L1 of the bevel region is consistent with the arc length of the bent arc, and the length L2 of the transition region is equal to the outer diameter of the bevel formed by the arc tip of the side plate III, so as to adapt to the arc structure of the steel pipe welding assembly.
[0009] A second aspect of the present invention also provides a welding process for butt welds of thick plates, based on the aforementioned transition structure, comprising the following steps: S1. Bevel pretreatment: Clean the bevel area of the thick plate transition structure and the bevel of the mating side plate to remove oil and rust; when the mating assembly includes a high alloy content side plate II, add a ceramic arc-inducing plate and a ceramic arc-extinguishing plate at both ends of the bevel. S2. Component fixing: The component to be welded is fixed on the positioner flipping platform by a clamp. The positioner flips and rotates the component so that the bevel on each side of the component to be welded is in the flat welding position. S3. Layered welding: Gas metal arc welding is used, and welding is carried out in the order of symmetrical root pass, alternating fill pass, and cover pass. During the welding process, the fill pass height and welding speed are controlled, and the arc is avoided at the butt joint or arc position of the transition structure. S4. Post-weld treatment: After welding, cut off the unstable arc-starting and arc-ending weld segments, and grind the weld to be flush with the surface of the thick plate; depending on the material characteristics of the components to be welded, selectively perform preheating before welding, interpass temperature control, or post-weld heat preservation; finally, perform UT and MT on the weld.
[0010] As an improvement, in step S3, the parameters for gas metal arc welding are as follows: The welding wire used is 1.2mm ER50-6 welding wire. The shielding gas is a mixture of 80% Ar and 20% CO2, with a flow rate of 15-20L / min. The welding current is 280-320A, the welding voltage is 30-34V, the fill height of a single weld bead is 4-6mm, and the welding speed is 300-500mm / min.
[0011] As an improvement, the temperature control and operation requirements in step S4 include: When the component to be welded includes side plate II with high alloy content, the preheating temperature before welding is 150-200℃, the interpass temperature is controlled at 150-300℃, and after welding, the component is reheated to 200-250℃ and held for 20 minutes, and covered with insulation cotton for insulation; when welding the weld between side plate II and side plate I, the root pass welding uses a φ16mm small sleeve welding gun, and the welding wire is welded in a small crescent oscillation manner to ensure the fusion of the base material on both sides of the bevel root, and it is forbidden to stop the arc at the arc position of side plate II; When the component to be welded is a steel pipe welding component, no preheating is required before welding, the interpass temperature is controlled at ≤300℃, and no heat preservation is required after welding.
[0012] As an improvement, the welding sequence for the box-type welded assembly is as follows: (a) When welding the cover plate and the side plate I, leave a 100mm unwelded section and grind the end of the weld to be obliquely upward. (b) After assembling the welded cover plate and side plate I with side plate II according to the dimensions, perform symmetrical root welding, alternating filling and cover welding on the weld seam between the cover plate and side plate II; (c) Welding the side plate I and side plate II, the weld starts from the 100mm unwelded section reserved at the upper cover plate and ends at the 100mm unwelded section reserved at the lower cover plate; (d) After all welds have been completed for 48 hours, perform UT and MT on the welds.
[0013] As an improvement, the welding sequence for the steel pipe welding assembly is as follows: (a) Weld the cover plate to the side plate III, weld to the end of the side plate III, and grind the end of the weld into an upward-sloping arc. (b) After assembling the welded cover plate and side plate III assembly with the steel pipe according to the dimensions, weld the cover plate and the steel pipe together. (c) Fillet welds for the circumferential welds between the side plate III and the steel pipe in sections: first weld to 50mm before the transition structure butt joint position II, then start from the reserved 50mm position and weld to another transition structure butt joint position II; during the welding process, it is strictly forbidden to extinguish the arc at the intersection of the welds of the transition structure butt joint position I and the transition structure butt joint position II; (d) After all welds have been completed for 24 hours, perform UT and MT on the welds.
[0014] In a third aspect, the present invention also provides an engineering machinery, which is a mining machinery, and the thick plate butt joint of the engineering machinery is provided with a transition structure for the thick plate butt weld. The transition structure is used for butt welding of the thick plates of the engineering machinery. Through the coordinated design of its bevel area and transition area, the smooth formation of the butt weld of the thick plate is achieved.
[0015] The transition structure for butt welds of thick plates disclosed in this invention is set at the end of the thick plate along the butt welding direction and includes a bevel area and a transition area connected in sequence. It is specifically adapted to the butt welding needs of thick plates in the field of mining machinery, and specifically solves the core pain points in existing thick plate butt welding technology. The specific beneficial effects are as follows: 1. Reduce welding operation difficulty and ensure weld quality stability. In existing technologies, the lack of a suitable transition structure during thick plate butt welding easily leads to abrupt structural changes at the butt joint, obstructing the welding torch's oscillation trajectory. This not only increases the difficulty of welding operations but also easily affects weld quality due to operational deviations. This invention ensures that the end face parameters β×D (β is the bevel angle, D is the bevel depth) of the bevel region in the transition structure are consistent with the bevel parameters of the butt joint side plate, ensuring a smooth structural transition at the butt joint position I. The welding torch can oscillate smoothly along the bevel contour, effectively avoiding the increased operational difficulty caused by poor structural transition and ensuring weld quality from the source of operation.
[0016] 2. Achieving a smooth structural transition and reducing the risk of welding defects. Existing technologies, lacking a transition area design, result in abrupt connections between beveled and non-beveled structures, easily leading to defects such as poor weld formation and inadequate sidewall fusion during welding, affecting joint reliability. This invention defines the transition area as an extension of the bevel area, using the β×D cross-section of the bevel area as the starting surface and the non-beveled end of the thick plate as the ending surface. This design achieves a smooth transition between the bevel and non-beveled structures, completely avoiding the aforementioned welding defects caused by abrupt structural changes in existing technologies, and significantly reducing the risk of welding defects.
[0017] 3. Optimize the quality of intersecting welds and avoid interference from minor structural changes. In existing technologies, the weld intersections at butt joint positions I (such as the weld between a side plate and a cover plate) are easily affected by minor structural changes, resulting in poor weld bead formation quality and affecting the overall welding effect. In the transition structure of this invention, the length of the bevel region is set to L1, and this bevel region is an extension of the bevel of the side plate at the butt joint position. This design can ensure the continuity of weld bead formation at the weld intersection of butt joint positions I, effectively avoid the adverse effects of minor structural changes in the transition region on the intersecting welds, and further improve the overall welding effect.
[0018] In summary, this invention can reliably achieve uniform weld bead filling and good weld transition, fully meeting the technical requirements for butt welding of thick plates in mining machinery, and providing a reliable solution for the high-quality manufacturing of thick plate components in mining machinery. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the transition structure formed by the welding process of the present invention; Figure 2 This is a schematic diagram of the butt welding of the thick plate transition structure of the present invention; Figure 3 This is a schematic diagram of the butt welding of the bent thick plate transition structure of the present invention; Figure 4 This is a schematic diagram of existing thick plate butt welding technology; In the diagram: 1. Cover plate, 2. Side plate I, 3. Side plate II, 4. Side plate III, 5. Steel pipe, 6. Transition structure, 7. Transition structure docking position I, 8. Transition structure docking position II, 9. Welding area I, 10. Welding area II, 11. Welding area III, 12. Welding area IV. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this application will be described in detail below through specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.
[0022] like Figure 1As shown, the transition structure for butt welds of thick plates of the present invention is provided at the end of the thick plate along the butt welding direction and includes two main functional sections: a bevel area and a transition area. It is suitable for thick plates used in mining machinery with a thickness t of 20-50mm. The specific design is as follows: Bevel area: The end face parameters of this area are β×D (β is the bevel angle, D is the bevel depth), and the length is L1; where β ranges from 20° to 45°, D ranges from 10 to 32 mm, and L1 ranges from 50 to 150 mm, and is used to form a matching connection with the bevel of the mating side plate. Transition zone: As an extension of the bevel zone, it takes the β×D section of the bevel zone as the starting surface and the non-bevel end of the thick plate as the ending surface, with a length of L2 (range 50-200mm). Through this transition zone, a smooth transition between the bevel and non-bevel structures can be achieved, fundamentally solving problems such as poor weld formation and poor sidewall fusion caused by structural abrupt changes in the existing technology. Example 1
[0023] Application of transition structure 6 in box-type welded assemblies.
[0024] like Figure 2 As shown, the box-type welded assembly in this embodiment is a commonly used load-bearing structure in mining machinery, including cover plate 1, side plate I 2 and side plate II 3. The processing and welding process of its transition structure is as follows: 1. Transition structure processing parameters (adapter cover plate 1) based on Figure 1 The basic design parameters of the transition structure 6 processed on the side of the end of the cover plate 1 are as follows: the thickness of the cover plate 1 is 45mm; the parameters of the bevel area are β=25°, D=25mm, and L1=80mm. Transition region parameters: L2=150mm; Connection optimization: An R100 fillet is set at the junction of the bevel area and the transition area to further avoid stress concentration caused by structural abrupt changes.
[0025] Meanwhile, a single-sided V-shaped bevel is machined around the perimeter of side plate I 2, and a single-sided V-shaped bevel is machined at the joint between side plate II 3 and cover plate 1 and side plate I 2. Furthermore, the bevel parameters (β×D) of all side plates are consistent with the bevel area parameters of the transition structure of cover plate 1 to ensure the fit between the plates.
[0026] 2. Welding process for box-type components The welding strategy employs regional division, attitude control, and fusion preservation. The specific steps are as follows: (1) Welding area I 9 (weld between cover plate 1 and side plate I 2) The box-shaped component is fixed on the positioner's flipping platform using a fixture. The positioner flips and rotates the component so that the bevel on each side is in the flat welding position, optimizing the welding operation angle and ensuring uniform weld filling. During welding, the weld is stopped 100mm in front of the transition structure 6, and the end of the weld is ground into an upward angle to reserve space for the subsequent welding arc termination of the transition structure. (2) Welding area II 10 (weld between cover plate 1 and side plate II 3) First, assemble the already welded cover plate 1 and side plate I 2 components with side plate II 3 according to the design dimensions. Add ceramic arc initiation plates and arc termination plates at both ends of the two V-shaped bevels with backing plates on cover plate 1 and side plate II 3 to avoid welding defects at the arc initiation / termination ends. After completing the bevel cleaning (removing oil and rust) and other pretreatment, fix the assembled components on the positioner flipping platform. Adjust the positioner to a symmetrical welding posture and perform symmetrical root pass, alternating fill, and cover pass welding on the two V-shaped bevels (control welding deformation and avoid component warping). After welding, cut off the unstable arc initiation weld section and arc termination weld section, and grind the weld to be flush with the surface of cover plate 1 to eliminate stress concentration points. (3) Welding area III 11 (weld between side plate I 2 and side plate II 3) The weld starts at the 100mm unwelded section reserved at the upper cover plate and ends at the 100mm unwelded section reserved at the lower cover plate, thus connecting with the weld of welding area I 9. Special note: The workpiece material of side plate II 3 has a high alloy content (which is prone to cold cracking during welding). Therefore, the welding of this area adopts gas metal arc welding (GMAW). The specific parameters are as follows: 1.2mm ER50-6 welding wire is used, the shielding gas is 80% Ar + 20% CO2 (gas flow rate 15-20L / min), the welding current is 280-320A, the voltage is 30-34V, the single pass fill height is 4-6mm, and the welding speed is 300-500mm / min. Temperature control requirements: Preheat to 150-200℃ before welding (to reduce welding restraint stress), maintain interpass temperature at 150-300℃ (to avoid embrittlement of the heat-affected zone), and postheat to 200-250℃ after welding and hold for 20 minutes (using insulation cotton for covering). Operational details: For the root pass welding, use a φ16mm small sleeve welding gun to reduce wire extension and improve current stability. Use a small crescent oscillation method for the welding wire to ensure full fusion of the base material on both sides of the bevel root. Do not stop the arc at the arc position of side plate II 3 to avoid weld defects at the arc end. 3. Welding quality assurance Due to the presence of transition structure 6, the bevel surface width from side plate II 3 workpiece to box-type assembly is in a gradual change of size; during cover welding, the fourth cover weld from side plate II 3 direction ends in the transition area, so that the cover weld gradually changes from 4 to 3 within a 150mm long transition section (avoiding stress concentration caused by abrupt weld transition); 48 hours after all welds are completed, UT (ultrasonic testing, to detect internal defects) and MT (magnetic particle testing, to detect surface defects) are performed to ensure that the welding quality meets the heavy-duty service requirements of mining machinery. Example 2
[0027] Application of transition structures in welded steel pipe assemblies.
[0028] like Figure 3 As shown, the steel pipe welding assembly of this embodiment is used for pipeline connection structure in mining machinery, including cover plate 1, side plate III 4, and steel pipe 5. Its transition structure and welding process are adapted to the arc feature design, as detailed below: 1. Transition structure processing parameters (for compatible bent cover plate 1) One end of the cover plate 1 is a bent arc structure (to fit the arc contour of the steel pipe 5), and the parameters of the transition structure 6 machined on the side of its end are as follows: Cover plate 1 thickness: 20mm; Bevel area parameters: β=45°, D=10.5mm, L1=130mm (consistent with the arc length of the bend in cover plate 1 to ensure the integrity of the bevel at the arc end). Transition area parameters: L2=80mm, and the length of the transition area L2 is equal to the outer diameter of the bevel formed by the arc tip of the side plate III 4 (to ensure the fit and connection with the steel pipe 5). Connection optimization: R100 fillet is also set at the junction of the bevel area and the transition area to avoid structural abrupt changes at the arc end; at the same time, a single-sided V-shaped bevel is machined around the perimeter of side plate III 4, and its bevel parameters (β×D) are consistent with the bevel area parameters of the transition structure of cover plate 1; the steel pipe 5 is tightly assembled with the arc structure of cover plate 1 and one end of side plate III 4 to ensure that the butt joint gap is ≤0.5mm, which meets the welding fusion requirements.
[0029] 2. Welding process for steel pipe assemblies The specific steps for arc butt welding and segmented welding are as follows: (1) Welding area I 9 (weld between cover plate 1 and side plate III 4) The components are fixed on the positioner flipping platform by the fixture, and the positioner is adjusted to make the bevel in the flat welding position. During welding, the weld is welded to the end of the side plate III 4, and the end of the weld is ground into an upward-sloping arc to match the arc contour of the steel pipe 5, in preparation for the subsequent welding connection of the transition structure. (2) Welding area II 10 (weld between cover plate 1 and steel pipe 5) First, assemble the welded cover plate 1-side plate III 4 assembly with the steel pipe 5. Add ceramic arc-starting plates and arc-ending plates at both ends of the two V-shaped bevels of the cover plate 1 and the steel pipe 5. After completing the bevel pretreatment, adjust to a symmetrical welding posture using a positioner. Use the same gas metal arc shielded welding parameters as in Example 1 (φ1.2mm ER50-6 welding wire, 80% Ar+20% CO2 shielding gas, etc.) to perform symmetrical root pass, alternating fill pass, and cover pass welding. After welding, cut off the arc-starting / arc-ending section and grind it flat. (3) Welding areas III and IV (circumferential fillet welds between side plate III 4 and steel pipe 5) A segmented welding strategy is adopted to avoid continuous welding stress at the arc end: Welding area III 11: Weld the fillet weld between the side plate III 4 and the steel pipe 5, and stop 50mm before the transition structure butt joint position II 8. Grind the end of the weld into an upward-sloping arc. Welding area IV 12: The fillet weld between the welding cover plate 1 and the steel pipe 5 starts from 50mm reserved at the transition structure butt joint position II 8, passes through the transition structure butt joint position I 7, and ends at 50mm reserved at another transition structure butt joint position II 8. Key requirement: It is strictly forbidden to extinguish the arc at the intersection of the weld seams at the transition structure joint position I 7 and the transition structure joint position II 8 (to avoid stress concentration and defect superposition at the intersection point).
[0030] 3. Welding quality assurance The weldability of the component material in this embodiment is better than that of the side plate II 3 in Embodiment 1. Therefore, the temperature control requirements are: no preheating before welding, interpass temperature ≤300℃, and no heat preservation after welding; the parameters of gas metal arc welding are consistent with those of Embodiment 1 (to ensure weld bead formation stability); UT and MT tests are performed 24 hours after all welds are completed to ensure no internal / surface defects.
[0031] like Figure 4As shown, in the prior art, when thick plates are butt-welded, only a single-sided V-shaped β×D bevel is opened on the side plate I 2, while the cover plate 1 has no transition structure. This design results in the structural dimensions of the cover plate 1 locally exceeding the bevel dimensions of the side plate I 2 at the butt-welding position I, forming a step-like structural abrupt change. When the welding torch passes through the butt-welding position I, it cannot achieve smooth swinging, which not only increases the difficulty of the welder's operation, but also easily leads to uneven weld filling (local accumulation / local incomplete filling), insufficient fusion depth of the side wall, and ultimately increases the risk of weld cracking.
[0032] This invention achieves the following technical advantages through a composite structural design of the bevel region and transition region, combined with parameter adaptation, posture control, and segmented welding process strategies: the bevel parameters of the transition structure are consistent with the bevel parameters of the butt side plate, ensuring smooth welding torch movement and avoiding increased operational difficulty; the transition region achieves a gradual change in size between the bevel and non-bevel, eliminating abrupt structural changes and reducing the risk of poor weld formation and fusion; the length L1 of the bevel region is an extension of the butt side plate bevel, avoiding the impact of slight changes in the transition region on the quality of the intersecting weld; and differentiated process parameters are adapted for different materials (such as high-alloy side plate II) and different structures (such as arc cover plate), ensuring stable welding quality. Example 3
[0033] An engineering machinery, specifically a commonly used piece of equipment in the field of mining machinery (such as a mining crusher and a mining belt conveyor), has a thick plate butt weld transition structure as described in any of the aforementioned embodiments at the jointing parts of the thick plates (such as the thick plate splicing joint of the crusher frame and the jointing node of the main beam of the conveyor).
[0034] The application scenarios and technical adaptations of the transition structure are as follows: Thick plate compatibility: The thickness t of the thick plates at the docking parts of engineering machinery is 20-50mm (e.g., Q345R steel with t=45mm is used for the frame thick plate, and NM450 wear-resistant steel with t=20mm is used for the main beam thick plate), which is fully compatible with the thick plate range of the transition structure. Structural Coordination: The transition structure achieves a smooth transition between the bevel area and the transition area through the coordinated design of the bevel area and the transition area. The β×D parameter of the bevel area (e.g., β=25°, D=25mm) is consistent with the single-sided V-shaped bevel of the butt plate. The L2 length of the transition area (e.g., 150mm) realizes the smooth transition between the bevel and the non-bevel, ultimately making the butt weld of the thick plate uniform and avoiding stress concentration caused by structural abrupt changes. Working condition adaptation: This transition structure can meet the structural strength requirements of mining machinery under heavy load (such as a single crushing load of ≥50kN for a crusher) and vibration (such as the working amplitude of a conveyor ≤5mm) conditions, ensuring that there is no risk of cracking or deformation of the weld at the joint, and improving the service stability and life of the engineering machinery.
[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A transition structure for butt welds in thick plates, characterized in that, Used for butt welding of thick plates in mining machinery, wherein the thickness t of the thick plate is 20-50mm; The transition structure is provided at the end of the thick plate along the butt joint direction of the thick plate, and includes a bevel area and a transition area connected in sequence. The end face parameter of the bevel region is β×D, where β is the bevel angle and D is the bevel depth, and the length of the bevel region is L1; the transition region is an extension structure of the bevel region, with the β×D section of the bevel region as the starting surface and the non-bevel end of the thick plate as the ending surface, and the length of the transition region is L2. The smooth transition between the bevel and non-bevel structures is achieved through the transition region. The bevel angle β is 20°-45°, the bevel depth D is 10-32mm, the length L1 is 50-150mm, and the length L2 is 50-200mm.
2. The transition structure for butt welds in thick plates according to claim 1, characterized in that, The junction between the bevel area and the transition area is provided with rounded corners to form a smooth transition, and the radius of the rounded corners is 80mm-120mm.
3. The transition structure for butt welds of thick plates according to claim 1 or 2, characterized in that, The transition structure is suitable for box-type welded assemblies in mining machinery; The box-type welding assembly includes a cover plate, side plate I, and side plate II. The transition structure is machined on the end side of the cover plate, and the bevel region parameter β×D of the transition structure is consistent with the single-sided V-shaped bevel parameter opened on side plate I and side plate II to achieve mating adaptation.
4. The transition structure for butt welds of thick plates according to claim 1 or 2, characterized in that, The transition structure is suitable for steel pipe welding assemblies in mining machinery; The steel pipe welding assembly includes a cover plate, a side plate III, and a steel pipe. One end of the cover plate is a bent arc structure, and the transition structure is machined on the side of the bent arc end of the cover plate. In the transition structure, the length L1 of the bevel region is consistent with the arc length of the bent arc, and the length L2 of the transition region is equal to the outer diameter of the bevel formed by the bevel at the tip of the arc of the side plate III, so as to adapt to the arc structure of the steel pipe welding assembly.
5. A welding process for butt welds of thick plates, characterized in that, Based on the transition structure described in any one of claims 1-4, the implementation includes the following steps: S1. Bevel pretreatment: Clean the bevel area of the thick plate transition structure and the bevel of the mating side plate to remove oil and rust; when the mating assembly includes a high alloy content side plate II, add a ceramic arc-inducing plate and a ceramic arc-extinguishing plate at both ends of the bevel. S2. Component fixing: The component to be welded is fixed on the positioner flipping platform by a clamp. The positioner flips and rotates the component so that the bevel on each side of the component to be welded is in the flat welding position. S3. Layered welding: Gas metal arc welding is used, and welding is carried out in the order of symmetrical root pass, alternating fill pass, and cover pass. During the welding process, the fill pass height and welding speed are controlled, and the arc is avoided at the butt joint or arc position of the transition structure. S4. Post-weld treatment: After welding, cut off the unstable arc-starting and arc-ending weld segments, and grind the weld to be flush with the surface of the thick plate; depending on the material characteristics of the components to be welded, selectively perform preheating before welding, interpass temperature control, or post-weld heat preservation; finally, perform UT and MT on the weld.
6. The welding process for butt welds of thick plates according to claim 5, characterized in that, In step S3, the parameters for gas metal arc welding are as follows: The welding wire used is 1.2mm ER50-6 welding wire. The shielding gas is a mixture of 80% Ar and 20% CO2, with a flow rate of 15-20L / min. The welding current is 280-320A, the welding voltage is 30-34V, the fill height of a single weld bead is 4-6mm, and the welding speed is 300-500mm / min.
7. The welding process for butt welds of thick plates according to claim 5 or 6, characterized in that, The temperature control and operation requirements in step S4 include: When the component to be welded includes side plate II with high alloy content, the preheating temperature before welding is 150-200℃, the interpass temperature is controlled at 150-300℃, and after welding, the component is reheated to 200-250℃ and held for 20 minutes, and covered with insulation cotton for insulation; when welding the weld between side plate II and side plate I, the root pass welding uses a φ16mm small sleeve welding gun, and the welding wire is welded in a small crescent oscillation manner to ensure the fusion of the base material on both sides of the bevel root, and it is forbidden to stop the arc at the arc position of side plate II; When the component to be welded is a steel pipe welding component, no preheating is required before welding, the interpass temperature is controlled at ≤300℃, and no heat preservation is required after welding.
8. The welding process for butt welds of thick plates according to claim 5, characterized in that, The welding sequence for the box-type welded assembly is as follows: (a) When welding the cover plate and the side plate I, leave a 100mm unwelded section and grind the end of the weld to be obliquely upward. (b) After assembling the welded cover plate and side plate I with side plate II according to the dimensions, perform symmetrical root welding, alternating filling and cover welding on the weld seam between the cover plate and side plate II; (c) Welding the side plate I and side plate II, the weld starts from the 100mm unwelded section reserved at the upper cover plate and ends at the 100mm unwelded section reserved at the lower cover plate; (d) After all welds have been completed for 48 hours, perform UT and MT on the welds.
9. The welding process for butt welds of thick plates according to claim 5, characterized in that, The welding sequence for the steel pipe welding assembly is as follows: (a) Weld the cover plate to the side plate III, weld to the end of the side plate III, and grind the end of the weld into an upward-sloping arc. (b) After assembling the welded cover plate and side plate III assembly with the steel pipe according to the dimensions, weld the cover plate and the steel pipe together. (c) Fillet welds for the circumferential welds between the side plate III and the steel pipe in sections: first weld to 50mm before the transition structure butt joint position II, then start from the reserved 50mm position and weld to another transition structure butt joint position II; during the welding process, it is strictly forbidden to extinguish the arc at the intersection of the welds of the transition structure butt joint position I and the transition structure butt joint position II; (d) After all welds have been completed for 24 hours, perform UT and MT on the welds.
10. An engineering machinery, characterized in that, The engineering machinery is mining machinery, and the thick plate butt joint of the engineering machinery is provided with a transition structure for the thick plate butt weld as described in any one of claims 1-4; The transition structure is used for butt welding of the thick plates of the engineering machinery. Through the coordinated design of its bevel area and transition area, the smooth formation of the butt weld of the thick plate is achieved.