In the field of wind power equipment, the diameter 300-500mm main shaft, as the core component of wind turbine transmission, directly determines the reliability of the unit's 20-year service cycle based on the roundness of the shaft neck (required to be ≤ 0.02mm) and the cylindricity of the bearing position (≤ 0.015mm). When a leading wind power equipment enterprise processes this type of 42CrMo quenched and tempered steel spindle, it faces a traditional process bottleneck: it needs to go through three processes: "horizontal lathe rough turning → floor boring machine semi precision turning → external cylindrical grinding machine precision grinding". Multiple clamping causes the coaxiality of the bearing position to exceed 0.05-0.08mm, and the bearing temperature rise during unit operation exceeds 45 ℃ (qualified value ≤ 40 ℃), with a single piece processing cycle of up to 16 hours; Simultaneously quenched and tempered steel (hardness 280-320HB) has high cutting resistance, and the lifespan of ordinary cutting tools is only 3-4 pieces per blade. The cost of single spindle cutting tools exceeds 3000 yuan.
To overcome this dilemma, the company has introduced the Wuhan heavy-duty machine tool VTC70 CNC vertical lathe to build a spindle exclusive manufacturing system of "heavy-duty rigid machining+one-time clamping full process". The equipment adopts an integral resin sand cast iron bed body (casting weight of 80 tons), which has undergone dual stress relief of "natural aging for 24 months+vibration aging for 120 hours", combined with static pressure guide rails (bearing capacity ≥ 300kN), and optimized structural rigidity through finite element analysis. The radial cutting stiffness reaches 55kN/mm, which can stably withstand 35kN radial force during 42CrMo cutting; Equipped with Fanuc 31i-B5 CNC system and laser interferometer dynamic compensation (positioning accuracy compensated to ± 0.005mm), combined with machine measuring arm (measurement accuracy ± 0.002mm), it achieves precise control of bearing position cylindricity ≤ 0.01mm. In response to the processing characteristics of high-strength steel, the equipment is equipped with an 18.5kW high-power spindle (maximum speed of 1000r/min) and a high-pressure internal cooling system (cooling pressure of 1.5MPa), combined with ultra-fine grain CBN cutting tools (hardness HV3500), effectively suppressing tool wear.
Customer usage scenarios
In terms of technological innovation, the equipment has achieved a dual breakthrough of "process integration+continuous precision control" in spindle machining: integrating a Φ 800mm four jaw hydraulic chuck (with a clamping force of 300kN), an 8-station turret (with a tool change time of 1.5 seconds), and an end face milling power head, which can complete spindle neck precision turning (roundness ≤ 0.015mm), bearing position precision boring (cylindricity ≤ 0.01mm), flange surface milling (flatness ≤ 0.03mm), and 12-16 connecting hole drilling and tapping (positional accuracy ≤ 0.15mm) in one go. In response to the problem of deflection control for ultra long spindles (length 3-5m), an innovative "multi-point support adaptive process" is adopted: through three sets of adjustable auxiliary supports, real-time compensation of workpiece self weight deformation (compensation accuracy 0.005mm) is achieved, ensuring stable control of the straightness of the entire axis length within ≤ 0.05mm/m; For precision machining of bearing positions, a "constant temperature machining environment+layered cutting method" is adopted, with the ambient temperature controlled at 20 ± 0.5 ℃ and the cutting depth of each layer controlled at 0.2-0.5mm. Combined with constant linear speed cutting (80-120m/min), the surface roughness is ensured to reach Ra0.8 μ m.
Clamping process
The implementation results fully comply with the standards of the wind power industry: the single piece processing cycle has been compressed from 16 hours to 9 hours, and the daily production capacity has been increased from 6 pieces to 11 pieces; The cylindricity of the main shaft bearing position is ≤ 0.01mm, and the coaxiality of the entire shaft is ≤ 0.03mm, fully meeting the requirements of GB/T 19073-2018 "Wind Turbine Gearbox" and GL certification; The temperature of the bearings during the operation of the unit increased to 36 ℃, and the vibration intensity decreased from 1.2mm/s to 0.6mm/s; The tool life has been extended by 150% (up to 8-10 pieces/blade) due to material matching, and the cost of single spindle tools has been reduced to 1200 yuan; The industrial Internet of Things system equipped on the equipment can collect cutting force (sampling frequency 1kHz) and spindle temperature in real time. Combined with the remaining life prediction model, the comprehensive utilization rate of the equipment has been increased from 70% to 92%, and the annual downtime has been reduced by 650 hours.
CKX52100 solves the industry contradiction between heavy-duty machining and micrometer level precision of wind turbine spindles. The production director of the company said, 'Now our 3MW wind turbine spindle has not only passed the verification of Goldwind Technology and Mingyang Intelligence, but also meets the ultimate requirements of' salt spray resistance and long life 'for offshore wind power, which has established a technical moat for us in the wind power equipment track.'. This case confirms that CNC vertical lathes have become the core equipment for breaking through performance bottlenecks in the field of wind power large-scale component manufacturing through the deep integration of "ultra rigid structure design+process precision closed-loop+intelligent operation and maintenance system".
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