Split rocker arm planet carrier and manufacturing method thereof

Abstract

The present application belongs to the technical field of coal mining equipment, and discloses a split type rocker arm planet carrier and a manufacturing method thereof, wherein the split type rocker arm planet carrier comprises a convex hub, a wheel seat and a side column, a first slot type welding interface of the convex hub and a second slot type welding interface of the wheel seat are provided with a radial opening, two ends of the side column are adapted to the radial opening, and the radial opening is matched with the two ends to form a welding slot. The convex hub, the wheel seat and the side column are precisely matched with performance requirements through differential material selection, and the balance between attribute requirements and cost is considered, and in view of the defects of poor split welding positioning accuracy and weak welding seam, through the structural design of the slot type welding interface and the side column, the welding accuracy and the overall strength are simultaneously ensured, and the reliability and the economy are also considered. The present application effectively solves the problem that the rocker arm planet carrier in the coal mining machine cannot consider the process, cost and strength requirements in the prior art.

Description

Technical Field

[0001] This invention belongs to the technical field of coal mining equipment, and particularly relates to a split-type rocker arm planetary carrier and a method for manufacturing the split-type rocker arm planetary carrier. Background Technology

[0002] As a core load-bearing component, the rocker arm planetary carrier of a coal mining machine must withstand a fault impact load of 3 times the rated torque. It must balance high strength, fatigue resistance, lightweight and cost control, and always faces the triple contradiction of process, cost and strength.

[0003] Traditional solutions all have drawbacks: while overall casting has low costs, uneven wall thickness can easily lead to sand holes and shrinkage porosity. A 0.5mm defect can cause cracks, and 70% of failures originate from this. The overall forging has a tensile strength of over 800MPa and fewer defects, but it is difficult to promote due to the material utilization rate of less than 60%, the cost of a single piece is 2-3 times higher, and the processing difficulty is high. Alternative solutions such as split bolt connections and local reinforcement either have poor reliability or only extend the service life by 15%, and have failed to break through the bottleneck.

[0004] The industry has proposed a split-type welding technology, breaking it down into three sub-structures: a torsion-transmitting hub, supporting side pillars, and a base wheel seat. However, new challenges have emerged: the stress on each component varies significantly, requiring the hub to resist torsion, the side pillars to resist impact, and the wheel seat to resist fatigue. In the case of a single-material solution, using all 42CrMo alloy steel results in insufficient toughness and high cost for the side pillars, while using all low-carbon steel lacks sufficient strength. Furthermore, direct welding makes precision control difficult, and the weld seam is prone to forming new, weaker areas, increasing the risk of structural failure and raising the overall danger factor. Summary of the Invention

[0005] To address some or all of the technical problems existing in the prior art, the present invention provides a split-type rocker arm planetary carrier and a method for manufacturing a split-type rocker arm planetary carrier, which connects hubs, wheel seats and side columns of different materials into one piece by welding, while taking into account the requirements of process, cost and strength.

[0006] In a first aspect, the present invention provides a split-type rocker arm planetary carrier, which is applied to a coal mining machine. The split-type rocker arm planetary carrier comprises: a hub, a wheel seat, and side columns. One end of the hub is a first spoke segment, which has multiple first groove-shaped weld joints. One end of the wheel seat is a second spoke segment, which has multiple second groove-shaped weld joints. Multiple side columns are provided. The hub, wheel seat, and side columns are made of different materials, and the first groove-shaped weld joints and / or the second groove-shaped weld joints have radial openings. Both ends of the side columns are adapted to the radial openings and, after engaging with the radial openings, form welding grooves. The hub is welded to one end of the side column, and the wheel seat is welded to the other end of the side column.

[0007] In some alternative implementations, the radial opening is a fan-shaped opening, the two ends of the side post are configured as fan-shaped structures, or the projection of the side post along its length is a fan shape, and the fan shape is adapted to the fan-shaped opening.

[0008] In some alternative implementations, in the projection along the length of the side post, the radial opening smoothly transitions to the outer ring of the first and / or second spoke segments, the apex of the radial opening smoothly transitions, the two sides of the side post smoothly transition to each other, and the two sides of the side post smoothly transition to the arc edges respectively.

[0009] In some alternative implementations, the hub is made of medium carbon alloy steel, the side post is made of low alloy high-strength steel, and the wheel seat is made of fine-grained steel.

[0010] Secondly, the present invention provides a method for manufacturing a split-type rocker arm planetary carrier, wherein the method for manufacturing the split-type rocker arm planetary carrier is applied to the manufacturing of the split-type rocker arm planetary carrier as described above, and the method includes: The convex hub is heat-treated, and the first welding surface and the second welding surface are machined along the axis away from the side post, respectively; Buffer layers are deposited on the first welding surface and the second welding surface, respectively. Remove the oxide layer from the welding area of ​​the side pillar; The wheel seat is preheated to remove hydrogen, and a nano-hydrogen-absorbing coating is applied to the welding area; Preheating treatment: the cam hub is preheated to 250°C to 310°C, the side pillar is preheated to 140°C to 160°C, and the wheel seat is preheated to 65°C to 95°C. The convex hub and the side post are welded together in sequence, and the side post and the wheel seat are welded together in sequence.

[0011] In some optional implementations, the heat treatment of the convex hub further includes: The convex hub is quenched at a temperature of 850°C to 910°C. After quenching, the convex hub is tempered at a temperature of 560°C to 600°C. Test the hardness. If the hardness is between 280HB and 320HB, proceed to the preheating treatment.

[0012] In some alternative implementations, the weld overlay buffer layer further includes: A nickel-based alloy layer is selected, with a thickness between 0.9 mm and 1.4 mm; The welding parameters are: current 100A to 140A, speed 75mm / min to 85mm / min, and welding shielding gas.

[0013] In some optional implementations, the welded hub and side post further include: For the root pass welding, a laser-arc hybrid welding process with a laser power of 2.8kW to 3.2kW and an arc current of 160A to 200A is selected. The welding parameters are: speed 0.8m / min and heat input ≤12kJ / cm. For filler welding, pulse welding is used with welding parameters of current 180A to 220A, EQNi70 welding wire, and liquid nitrogen spray cooling to 75°C to 80°C. For cover welding, the welding parameters are current 135A to 165A, speed 110mm / min to 130mm / min, and ER55-G welding wire.

[0014] In some optional implementations, the welded side post and wheel seat further include: For the root pass: use double-wire submerged arc welding with welding parameters of 480A to 520A for the front wire and 382A to 410A for the rear wire, and a speed of 39cm / min to 41.5cm / min. Filler welding: Use multi-pass oscillating welding, oscillation width ≤15mm, interpass temperature ≤100℃; Cover welding: Use low-hydrogen welding rod J506, current 120A to 140A, heat treatment 240℃ to 260℃, time 28 to 35 minutes.

[0015] In some alternative implementations, after welding is completed, the method further includes: Laser impact is applied to the fusion line between the convex hub and the side post; Stress-relief annealing of the split rocker planetary carrier is performed by holding at a temperature of 575°C to 585°C for at least 3 hours. Vibration aging was performed with parameters of 115Hz to 125Hz frequency, 0.55mm to 0.65mm amplitude, and 23 to 28 minutes. Grinding and shaping of the weld seam, controlling the reinforcement height to be between 0.3 and 0.5 mm, and ensuring a smooth transition in the arc area with Ra ≤ 3.2 μm; Shot peening of top / bottom corners with 200% coverage introduces compressive stress of -450MPa.

[0016] The main advantages of the technical solution of this invention are as follows: This invention provides a split-type rocker arm planetary carrier and its manufacturing method. The split-type rocker arm planetary carrier precisely matches performance requirements through differentiated material selection, balancing property requirements and cost. Addressing the shortcomings of existing split-type welding methods, such as poor positioning accuracy and weld seams easily becoming weak points, this invention utilizes a grooved weld joint and side column structural design to simultaneously ensure welding accuracy and overall strength. The use of split-type welding technology effectively improves manufacturing feasibility, achieving a balance between reliability and economy. This invention effectively solves the problem in existing technologies where rocker arm planetary carriers in coal mining machines cannot simultaneously meet process, cost, and strength requirements. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and constitute a part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a cross-sectional schematic diagram of a split-type rocker arm planetary carrier provided in an embodiment of the present invention.

[0018] Figure 2 This is a side view schematic diagram of a split-type rocker arm planetary carrier provided in an embodiment of the present invention.

[0019] Figure 3 The diagram shows a front view and a cross-sectional view of the hub of a split rocker arm planetary carrier according to an embodiment of the present invention.

[0020] Figure 4 The diagram shows a front view and a cross-sectional view of the wheel seat of a split rocker arm planetary carrier according to an embodiment of the present invention.

[0021] Figure 5 A schematic diagram of the end face and a bottom view of the side column of a split-type rocker arm planetary carrier provided in an embodiment of the present invention.

[0022] Figure 6 This is a flowchart illustrating a method for manufacturing a split-type rocker arm planetary carrier according to an embodiment of the present invention.

[0023] Figure 7 This is a schematic diagram illustrating the specific process of heat treatment of the convex hub in the manufacturing method of the split rocker arm planetary carrier provided in an embodiment of the present invention.

[0024] Figure 8This is a schematic diagram illustrating the specific process after welding is completed in the manufacturing method of the split rocker arm planetary carrier provided in an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures: 10. Hub; 11. First spoke section; 111. First grooved weld joint; 12. Wheel hub; 20. Wheel seat; 21. Second spoke section; 211. Second grooved weld joint; 22. Bearing support position; 30. Side post. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0027] The technical solutions provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] refer to Figure 1 and Figure 2 This invention provides a split-type rocker arm planetary carrier, which is applied to a coal mining machine. The rocker arm planetary carrier includes: a hub 10, a wheel seat 20, and side columns 30. One end of the hub 10 is a first spoke section 11, which is provided with multiple first groove-shaped welding ports 111. One end of the wheel seat 20 is a second spoke section 21, which is provided with multiple second groove-shaped welding ports 211. Multiple side columns 30 are provided. The hub 10, wheel seat 20, and side columns 30 are made of different materials, and the first groove-shaped welding ports 111 and / or the second groove-shaped welding ports 211 are provided with radial openings. The two ends of the side columns 30 are adapted to the radial openings and form welding grooves after fitting with the radial openings. The hub 10 is welded and fixed to one end of the side column 30, and the wheel seat 20 is welded and fixed to the other end of the side column 30.

[0029] In this embodiment of the invention, addressing the limitations of existing split-welded structures due to the imbalance of properties of the same material and the restriction of the application of dissimilar materials, the present invention selects suitable materials for the hub 10, side pillar 30, and wheel seat 20: the hub 10 is made of medium-carbon alloy steel, such as 42CrMo, to meet the high strength and wear resistance required for transmitting high torque; the side pillar 30 can be made of low-alloy high-strength steel, such as Q460, to cope with fault impact loads with a balance of strength and toughness; the wheel seat 20 is made of fine-grained steel, such as Q345, to control costs while ensuring basic rigidity and fatigue resistance. This selection scheme avoids the problems of high cost and insufficient toughness caused by using all 42CrMo, and strength defects caused by using all low-carbon steel.

[0030] Compared to the machining method of integral forging, the selection of welding process increases material utilization by more than 40%, reduces unit cost by more than 50%, and ensures that the performance of each component is precisely matched with the stress requirements, which can fundamentally solve the problem of matching material performance with cost.

[0031] To address the shortcomings of existing split-type welding, such as poor positioning accuracy and the tendency for welds to become weak areas, this invention utilizes a radial opening and a matching structure with the side column 30 to form a natural positioning reference, effectively avoiding the alignment deviation of traditional direct welding. This improves the structural morphology accuracy by more than 30% after welding. The welding groove confines the weld to a preset area, and the smooth transition design of the fan-shaped opening and the side column 30 avoids stress concentration caused by sharp notches. The impact load resistance of the weld area is improved by 40% compared to existing direct-welded structures. The dual welding groove structure ensures uniform stress distribution in the fusion zone, solving the problem of weak areas formed by welding defects in the axial direction. This completely eliminates the risk of preferential weld failure in existing split-type structures and extends the service life by more than 60% compared to locally reinforced castings.

[0032] Compared to traditional integral casting and forging methods, the split structure design of this invention significantly reduces manufacturing difficulty: it eliminates the need to address the uneven wall thickness defects inherent in integral casting, avoids 70% of the failure risks caused by casting pinholes and shrinkage cavities, and eliminates the drawbacks of integral forging, such as less than 60% material utilization and costs 2 to 3 times higher. Simultaneously, the manufacturing method incorporates preheating control, buffer layer welding, and stress-relief annealing processes for welding dissimilar steels, effectively suppressing heat-affected zone hardening and residual stress in the weld. The weld joint flaw detection pass rate reaches over 95%, and the dynamic stiffness is increased by 5 times compared to existing split bolt connection structures. This completely solves the industry pain point of high cost for sufficient strength and poor reliability for low cost, achieving the triple goals of high strength, low cost, and ease of manufacturing.

[0033] Finite element analysis of the planetary carrier of the coal mining machine rocker arm under typical load conditions revealed significant non-uniformity in its stress distribution. The analysis showed that stress peaks were mainly concentrated in the tooth root region of the planetary gear contact and the bearing support position 22 of the wheel seat 20. These areas bear high cyclic alternating stress loads and are key stress concentration points in the structure.

[0034] Based on the above finite element analysis results, in order to facilitate in-depth analysis of structural stress and implement targeted design optimization, such as... Figures 1 to 5 As shown, the complex structure of the planetary carrier is rationally decomposed into three functionally distinct substructures: the hub 10, which mainly bears torque transmission; the side pillars 30, which connect and provide support; and the wheel seat 20, which provides overall basic rigidity. This decomposition method clearly defines the mechanical function and stress characteristics of each part.

[0035] It should be noted that, as Figure 2 As shown in the figure, finite element analysis clearly indicates that hub 12 is the main stress concentration area under load conditions. If hub 12 is designed as an independent split structure and connected by welding, new and weaker areas are easily formed at the weld, which will significantly increase the risk of structural failure and raise the danger factor. Therefore, we optimized the design: a petal-shaped first spoke section 11 was added below hub 12, and it was designed as an integral structure with hub 12, namely convex hub 10. By using a fine design with root arc and stepped transition at the connection, the stress is guided and dispersed, so that the stress originally highly concentrated on hub 12 can be more smoothly transitioned and distributed to the spoke area.

[0036] Accordingly, an optimized welding design scheme is proposed: the main welds are arranged in a specific area where the side post 30 connects to the hub 10 and the wheel seat 20. This area has been verified by finite element analysis to be a low-stress zone with relatively low stress, and this location also facilitates subsequent non-destructive testing operations.

[0037] It is understandable that the core risks and solutions for welding dissimilar steels lie in the following points: The risk of cold cracking caused by the high carbon equivalent of 42CrMo is due to the easy formation of martensitic hardening structure in the weld heat-affected zone, accompanied by the accumulation of diffusing hydrogen. To address this problem, a combination of measures, including gradient preheating and hydrogen-free weld beads, can be adopted.

[0038] The difference in the coefficients of linear expansion of the materials is the fundamental cause of residual stress concentration in the fusion zone, which may lead to stress peaks. This can be effectively mitigated by implementing a symmetrical heat source welding process, combined with subsequent laser shock peening treatment.

[0039] To address the toughness and impact resistance requirements of the Q460 side pillar 30, and considering that welding thermal cycling may lead to HAZ grain coarsening and embrittlement, narrow-gap TIG welding was selected to refine the grains and ensure toughness.

[0040] Finally, to prevent carbon in 42CrMo from diffusing into the low-alloy steel side and forming a brittle carbide layer (i.e., the carbon migration problem), a nickel-based buffer layer was used, along with silicon controlled welding wire, to block or control the carbon migration path. These measures together constitute the technical solution of this invention for addressing the challenges of welding dissimilar steels.

[0041] refer to Figures 1 to 5 In some optional implementations of the present invention, the radial opening is a fan-shaped opening, and the two ends of the side post 30 are set as fan-shaped structures, or the projection of the side post 30 along its length direction is a fan shape, and the fan shape is adapted to the fan-shaped opening.

[0042] The matching design of the fan-shaped opening and the fan-shaped structure of the side column 30 forms a guiding benchmark. During installation, the fan-shaped end of the side column 30 can quickly slide into the preset position along the arc surface of the opening without repeated adjustments for alignment. At the same time, the asymmetrical shape of the fan-shaped structure has a foolproof property, which can directly avoid assembly errors such as reverse installation or misalignment of the side column 30.

[0043] Meanwhile, the fan-shaped adapter structure creates a regular arc-shaped fusion space in the welding groove. Compared with irregular interfaces, this allows the welding heat source to act more evenly on the fusion zone, reducing defects such as incomplete fusion and slag inclusions caused by uneven interface gaps.

[0044] In addition, the arc transition characteristics of the fan-shaped structure can effectively eliminate stress concentration in the opening area. The smooth connection between the radial opening and the outer ring of the spoke section, and the arc design of the 30 fan-shaped side of the side column can disperse and transfer the peak stress under the fault impact load along the arc surface.

[0045] refer to Figures 1 to 5 In some optional implementations of the present invention, in the projection along the length direction of the side post 30, the radial opening smoothly transitions with the outer ring of the first spoke segment 11 and / or the second spoke segment 21, the apex of the radial opening smoothly transitions, the two sides of the side post 30 smoothly transition, and the two sides of the side post 30 smoothly transition with the arc edge respectively.

[0046] The welding area is designed as a fan-shaped structure with rounded corners at both the top and bottom to effectively avoid stress concentration caused by sharp notches. This design not only allows residual welding stress to be dispersed from the inside out along the fan-shaped path, significantly smoothing the stress transmission path, but also effectively reduces the local stress concentration factor, thereby improving the overall fatigue strength and structural reliability of the planetary carrier.

[0047] In some optional implementations of the present invention, the material of the hub 10 is medium carbon alloy steel, the material of the side post 30 is low alloy high strength steel, and the material of the wheel seat 20 is fine grain steel.

[0048] Secondly, refer to Figure 6 A method for manufacturing a split-type rocker arm planetary carrier is provided. This method is applied to the manufacturing of the split-type rocker arm planetary carrier described above. The manufacturing method includes: S10, heat-treat the cam hub 10, and machine the first welding surface and the second welding surface respectively along the axis away from the side column 30.

[0049] This step first ensures that the convex hub 10 has a certain hardness and strength before welding, reducing the deformation and stress generated by welding, thereby improving accuracy.

[0050] The first and second welding surfaces are used to form two different welding grooves for welding from the two end faces in the axial direction.

[0051] In some alternative implementations, the chamfer angle of the first welding surface is 30 degrees, and the chamfer angle of the corresponding second welding surface is -45 degrees. This can form an asymmetrical fan-shaped welding bevel, creating asymmetrical welding points on both axial end faces of the first spoke segment 11.

[0052] S20, a buffer layer is deposited on both the first and second weld surfaces. The buffer layer is designed to block carbon migration, with a carbon diffusion zone width ≤ 10 μm. This is understandable, as the conventional carbon diffusion zone width is > 50 μm, thus effectively preventing brittle martensite bands.

[0053] S30, Remove the oxide layer from the welded area of ​​the side pillar 30. This step is designed to prevent defects during the welding process. Specifically, ultrasonic testing can be performed before removing the oxide layer to confirm the absence of delamination defects, followed by oxide layer removal, achieving a surface roughness of Ra3.2.

[0054] Furthermore, after removing the oxide layer, a compressive stress groove is pre-placed in the apex arc area of ​​the welding area of ​​the side column 30, that is, the position that adapts to the first welding surface and the second welding surface. This groove is used to form a receiving groove for the solder and at the same time absorbs the welding shrinkage stress and prevents the fan-shaped corner from cracking.

[0055] In some optional implementations, the top corner arc area of ​​the side pillar 30 is pre-set with a compressive stress groove, which can be R15mm×2mm deep, and the bottom corner arc area is pre-set with a deep compressive stress groove, which can be R5mm×2mm deep.

[0056] S40, preheating and dehydrogenating the wheel seat 20, and coating the welding area with a nano hydrogen-absorbing coating.

[0057] S50, preheating treatment: the hub 10 is preheated to 250°C to 310°C, the side post 30 is preheated to 140°C to 160°C, and the wheel seat 20 is preheated to 65°C to 95°C. In a preferred embodiment, the hub 10 is preheated to 280°C, the side post 30 is preheated to 150°C, and the wheel seat 20 is preheated to 80°C.

[0058] S60, the convex hub 10 and the side pillar 30 are welded in sequence, and the side pillar 30 and the wheel seat 20 are welded in sequence.

[0059] Positioning welding can be performed sequentially. A special magnetic clamp for fan-shaped welds is used to forcibly constrain the deformation of the arc area. The gap is ≤0.1mm. ER110S-G (welding wire tensile strength ≥800MPa) is used. Short-segment skip welding (each segment ≤20mm) is performed. Welding is carried out immediately after preheating. Positioning welding is only used for straight segments, that is, the plane area connecting the two ends of the arc. Positioning welding in the arc area is prohibited.

[0060] Further, refer to Figure 7 In some optional implementations, the heat treatment of the cam hub 10 also includes: S11, the convex hub 10 is quenched at a temperature of 850°C to 910°C. In a preferred embodiment, the quenching temperature is 880°C.

[0061] S12, after quenching, the cam hub 10 is tempered at a temperature of 560°C to 600°C. In a preferred embodiment, the tempering temperature is 580°C.

[0062] S13, test the hardness. If the hardness is between 280HB and 320HB, proceed to the preheating treatment.

[0063] Furthermore, in some alternative implementations, the weld overlay buffer layer also includes: A nickel-based alloy layer is selected, with a thickness between 0.9 mm and 1.4 mm. Specifically, the preferred nickel-based alloy layer is an ERNiCrMo-3 nickel-based alloy layer.

[0064] The welding parameters are: current 100A to 140A, speed 75mm / min to 85mm / min, and welding shielding gas.

[0065] Specifically, the preferred welding parameters are a current of 120A, a speed of 80mm / min, and a preferred shielding gas of argon.

[0066] Furthermore, in some alternative implementations, the welded hub 10 and side post 30 also include: S61, root pass welding, using laser and arc hybrid welding with laser power of 2.8kW to 3.2kW and arc current of 160A to 200A, welding parameters are speed 0.8m / min, heat input ≤12kJ / cm.

[0067] Specifically, laser-arc hybrid welding (laser power 3kW + arc current 180A) is used with ER90S-G welding wire (Ceq=0.45%, diffusible hydrogen ≤1.5mL / 100g). The core advantage lies in its low-strength matching characteristics. Through plastic deformation, it absorbs stress, suppressing the cold cracking tendency of high carbon equivalent 42CrMo (Ceq=0.91%). Simultaneously, the nickel content (1.25-2.0%) refines the weld grain, ensuring an impact energy ≥80J (measured value 82J), thus resolving the contradiction between high-strength base material and high-toughness requirements in dissimilar steel welding. The optimal welding parameters are: welding speed 0.8m / min, heat input ≤12kJ / cm, 50% improvement in weld penetration uniformity, and adaptability to changes in fan-shaped slope.

[0068] S62, filler welding, pulse welding, welding parameters are current 180A to 220A, using EQNi70 welding wire, liquid nitrogen spray cooling to 75℃ to 80℃.

[0069] Specifically, pulse welding (80%Ar+20%CO2) is selected, the current is 200A, EQNi70 welding wire (containing 70% Ni) is used, liquid nitrogen is sprayed to 80℃, interlayer cooling is used to refine the grains, nickel-based welding wire inhibits carbon migration, and the dilution rate is ≤15%.

[0070] S63, cover pass welding, welding parameters are current 135A to 165A, speed 110mm / min to 130mm / min, using ER55-G welding wire.

[0071] Specifically, narrow-gap TIG welding with 0.3% rare earth Y2O3 is used, with preferred parameters of 150A current and 120mm / min. ER55-G welding wire is used, which utilizes the characteristics of high rare earth deoxidation combined with low crack sensitivity to deeply deoxidize and suppress porosity and slag inclusions. At the same time, the low silicon design ensures the density and corrosion resistance of the weld surface.

[0072] Furthermore, in some alternative implementations, welding the side post 30 and the wheel seat 20 also includes: S64, root pass: Use twin-wire submerged arc welding with welding parameters of 480A to 520A for the front wire and 382A to 410A for the rear wire, and a speed of 39cm / min to 41.5cm / min.

[0073] Specifically, the preferred welding parameters for twin-wire submerged arc welding are: 500A for the front wire and 400A for the rear wire, speed of 40cm / min, and a 30% reduction in heat input to avoid overheating of the Q345 material.

[0074] S65, filler weld: use multi-pass oscillation welding, oscillation width ≤15mm, interpass temperature ≤100℃. This method can refine the grains in the fan-shaped region, making its hardness gradient ≤30HV / mm.

[0075] S66, Cover Weld: Use low-hydrogen electrode J506, current 120A to 140A, postheating 240℃ to 260℃, time 28 to 35 minutes. Low-hydrogen electrode J506, segmented back welding reduces residual stress by 40%, current 130A, postheating 250℃ for 30 minutes, preventing cold cracking.

[0076] refer to Figure 8 In some alternative implementations, after welding is completed, the method also includes: S70, laser impact is applied to the fusion line between the convex hub 10 and the side pillar 30.

[0077] This step is used to improve fatigue life.

[0078] S80, stress-relief annealing of split rocker arm planetary carriers, held at 575°C to 585°C for at least 3 hours.

[0079] This step is used to eliminate most of the residual stress. Preferably, the temperature is maintained at 580°C for 3 hours.

[0080] S90, subjected to vibration aging with parameters of 115Hz to 125Hz frequency, 0.55mm to 0.65mm amplitude, and 23 to 28 minutes.

[0081] This step is used to eliminate the remaining 30% of residual stress. Preferably, vibration aging is performed with parameters of 1120 Hz frequency, 0.6 mm amplitude, and 25 minutes.

[0082] S100, grinding and shaping of weld seam, control the reinforcement height to 0.3 to 0.5 mm, smooth transition of arc area Ra≤3.2 μm.

[0083] This step is used to eliminate stress concentration.

[0084] S110 shot peening for top / bottom corners, 200% coverage, introduces -450MPa compressive stress.

[0085] This step is used to increase fatigue strength by 30%.

[0086] Understandably, after the welding process is completed, in order to obtain a finished planetary carrier with excellent performance and meeting precision requirements, the following key processing and heat treatment steps need to be performed in sequence: First, the welded planetary carrier is subjected to quenching and tempering treatment, through quenching and high-temperature tempering, to optimize the overall microstructure, including the weld and heat-affected zone, and ensure uniform and good comprehensive mechanical properties; Next, a finishing process is carried out, according to the design drawings, to precisely machine various features of the planetary carrier, including dimensional, shape, and positional tolerances, while ensuring that the surface roughness of the machined surface meets the predetermined standard, laying the foundation for subsequent surface strengthening treatment; Finally, the entire part is subjected to nitriding treatment, by forming a dense nitrided layer on the workpiece surface with high hardness, excellent wear resistance, and certain corrosion resistance, to further improve the overall service performance and life of the part.

[0087] In summary, compared with the prior art, the modular rocker arm planetary carrier and its manufacturing method of the present invention have the following advantages and beneficial effects: The fan-shaped weld structure provided by this invention is precisely positioned in a low-stress zone based on finite element analysis. By optimizing the weld contour into a fan-shaped geometry with a circular arc transition, the distribution path of residual stress is altered. This design promotes the release of welding residual stress along a radial gradient, avoiding stress accumulation at sharp corners, as is common in traditional straight welds. Theoretical analysis shows that this structure can reduce the stress concentration factor at the weld root from 3.2 to 1.8, significantly alleviating stress concentration problems and enhancing the overall strength and durability of the structure.

[0088] Nickel-based buffer layer: This invention incorporates an ERNiCrMo-3 nickel-based alloy buffer layer with a thickness of 1.2 mm at the welding interface between 42CrMo and Q460 dissimilar metals. The high nickel content (≥58%) of this buffer layer provides excellent diffusion barrier properties. Since nickel has a much lower affinity for carbon than chromium and iron, this high-nickel buffer layer effectively inhibits the migration and diffusion of carbon atoms from the 42CrMo base metal towards the Q460 side during welding thermal cycling, thereby fundamentally preventing the formation of a continuous, network-like brittle Fe3C carbide phase near the fusion zone. Consequently, the weld joint interface is purified, and its shear strength is significantly improved.

[0089] Gradient preheating process: This invention compensates for the thermal expansion differences between 42CrMo and Q460, and between Q460 and Q345, through a gradient preheating process. This process results in a smooth hardness transition in the heat-affected zone, thereby significantly reducing residual stress in the joint and suppressing the formation of cold cracks.

[0090] Laser shock fusion strengthening: This invention employs laser shock fusion strengthening technology, utilizing high-energy laser-induced plasma shock waves to form a residual compressive stress layer with a depth of up to 0.8 mm on the surface of the fusion line. This compressive stress layer can effectively improve the fatigue limit of the joint and effectively inhibit crack initiation and propagation, avoiding brittle fracture.

[0091] This invention achieves a significant improvement in weld quality through a synergistic process of preheating, hydrogen removal, and TIG remelting. The process utilizes TIG remelting to refine the grain to ASTM grade 10 (compared to the conventional grade 8) and eliminate porosity (maximum size 0.1 mm), thus improving the joint's mechanical properties. Combined with pre- and post-weld hydrogen removal treatment, which controls the hydrogen content below 0.5 mL / 100g, the invention synergistically inhibits crack initiation through both microstructure refinement and hydrogen content control, effectively preventing component failure due to weld defects.

[0092] Therefore, this invention systematically solves multiple problems in existing technologies through triple synergistic innovation of "geometry-materials-process," and brings comprehensive benefits: In terms of inspection and manufacturing: A modular structure is adopted, allowing each component to undergo independent ultrasonic testing, effectively reducing blind spots by 80%. Simultaneously, this design simplifies part structure, facilitating the use of more economical processing techniques and significantly reducing scrap rates. Ultimately, material utilization is increased to over 95%, and processing cycles are shortened by 60%. In terms of materials and structural design: the optimized configuration of three materials clearly defines the function and stress characteristics of each part. Combined with the fan-shaped structural design, the stress transmission path is optimized, increasing the overall load-bearing capacity of the planetary carrier by 30%.

[0093] Regarding welding processes and performance: Four core technologies were innovatively adopted: zoned gradient preheating, nickel-based buffer layer, laser shock peening, and preheating-induced hydrogen removal TIG remelting. These technologies collaboratively addressed key risks such as cold cracking, carbon migration, heat-affected zone embrittlement, and residual stress concentration, ensuring the inspectability and high reliability of the weld zone. Furthermore, by optimizing the weld path to avoid critical mating surfaces (such as planetary gear shaft holes) and supplementing this with ultrasonic testing, product quality was further guaranteed.

[0094] In terms of product performance and lifespan: The combined application of the above innovations extends the service life of the planetary carrier under heavy load conditions to more than twice that of the traditional structure.

[0095] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Additionally, the terms "front," "back," "left," "right," "upper," and "lower" in this document refer to the placement shown in the accompanying drawings.

[0096] 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A split-type rocker arm planetary carrier, wherein the split-type rocker arm planetary carrier is used in a coal mining machine, characterized in that, The split-type rocker arm planetary carrier includes: A convex hub, one end of which is a first spoke segment, the first spoke segment being provided with a plurality of first groove-shaped weld joints; Wheel seat, one end of which is a second spoke section, the second spoke section being provided with multiple second groove-shaped weld joints; and Side pillars, wherein multiple side pillars are provided; The hub, wheel seat, and side post are made of different materials, and the first groove-shaped weld joint and / or the second groove-shaped weld joint are provided with radial openings. The two ends of the side post are adapted to the radial openings and form a weld groove after cooperating with the radial openings. The hub is welded and fixed to one end of the side post, and the wheel seat is welded and fixed to the other end of the side post.

2. The split-type rocker arm planetary carrier according to claim 1, characterized in that, The radial opening is a fan-shaped opening, and the two ends of the side column are set as fan-shaped structures, or the projection of the side column along its length direction is a fan shape, and the fan shape is adapted to the fan-shaped opening.

3. The split-type rocker arm planetary carrier according to claim 2, characterized in that, In the projection along the length of the side post, the radial opening smoothly transitions to the outer ring of the first and / or second spoke segments, the apex of the radial opening smoothly transitions, the two sides of the side post smoothly transition to each other, and the two sides of the side post smoothly transition to the arc edges respectively.

4. The split-type rocker arm planetary carrier according to claim 1, characterized in that, The hub is made of medium carbon alloy steel, the side post is made of low alloy high strength steel, and the wheel seat is made of fine grain steel.

5. A method for manufacturing a split-type rocker arm planetary carrier, applied to the manufacturing of a split-type rocker arm planetary carrier as described in any one of claims 1 to 4, characterized in that, The manufacturing method includes: The convex hub is heat-treated, and the first welding surface and the second welding surface are machined along the axis away from the side column, respectively; Buffer layers are deposited on the first welding surface and the second welding surface, respectively. Remove the oxide layer from the welded areas of the side pillars; Preheat the wheel seat to remove hydrogen, and apply a nano-hydrogen-absorbing coating to the welding area; Preheating treatment: preheat the hub to 250°C to 310°C, the side pillar to 140°C to 160°C, and the wheel seat to 65°C to 95°C. The cam hub and side post are welded in sequence, and the side post and wheel seat are welded in sequence.

6. The method for manufacturing a split-type rocker arm planetary carrier according to claim 5, characterized in that, The heat treatment for cam hubs includes: The convex hub is quenched at a temperature of 850℃ to 910℃. After quenching, the convex hub is tempered at a temperature of 560℃ to 600℃. Test the hardness. If the hardness is between 280HB and 320HB, proceed to the preheating treatment.

7. The method for manufacturing a split-type rocker arm planetary carrier according to claim 5, characterized in that, The weld overlay buffer layer includes: A nickel-based alloy layer is selected, with a thickness between 0.9 mm and 1.4 mm; The welding parameters are: current 100A to 140A, speed 75mm / min to 85mm / min, and welding shielding gas.

8. The method for manufacturing a split-type rocker arm planetary carrier according to claim 5, characterized in that, Welded hub and side pillars include: For the root pass welding, a laser-arc hybrid welding process with a laser power of 2.8kW to 3.2kW and an arc current of 160A to 200A is selected. The welding parameters are: speed 0.8m / min and heat input ≤12kJ / cm. For filler welding, pulse welding is used with welding parameters of current 180A to 220A, EQNi70 welding wire, and liquid nitrogen spray cooling to 75°C to 80°C. For cover welding, the welding parameters are current 135A to 165A, speed 110mm / min to 130mm / min, and ER55-G welding wire.

9. The method for manufacturing a split-type rocker arm planetary carrier according to claim 5, characterized in that, Welded side pillars and wheel seats include: For the root pass: use double-wire submerged arc welding with welding parameters of 480A to 520A for the front wire and 382A to 410A for the rear wire, and a speed of 39cm / min to 41.5cm / min. Filler welding: Use multi-pass oscillating welding, oscillation width ≤15mm, interpass temperature ≤100℃; Cover welding: Use low-hydrogen welding rod J506, current 120A to 140A, heat treatment 240℃ to 260℃, time 28 to 35 minutes.

10. The method for manufacturing a split-type rocker arm planetary carrier according to claim 5, characterized in that, After welding is completed, the method further includes: Laser impact is applied to the fusion line between the hub and the side pillar; Stress-relief annealing of the split rocker planetary carrier is performed by holding at a temperature of 575°C to 585°C for at least 3 hours. Vibration aging was performed with parameters of 115Hz to 125Hz frequency, 0.55mm to 0.65mm amplitude, and 23 to 28 minutes. Grinding and shaping of the weld seam, controlling the reinforcement height to be between 0.3 and 0.5 mm, and ensuring a smooth transition in the arc area with Ra ≤ 3.2 μm; Shot peening of top / bottom corners with 200% coverage introduces compressive stress of -450MPa.

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