In mechanical transmission systems, the radial runout (requirement ≤0.05mm) and face runout (≤0.04mm) of gears with a pitch circle diameter of Φ300-500mm directly determine the transmission efficiency and equipment lifespan. A heavy-duty gear manufacturer processing gears made of 40CrNiMoA material using traditional methods requires three processes: 'rough turning on a horizontal lathe → milling the end face on a vertical milling machine → shaping the tooth profile on a gear shaper.' Multiple setups result in radial runout exceeding the tolerance by 0.08-0.12mm, transmission noise exceeding 90dB (acceptable value ≤85dB), and a single piece processing cycle as long as 10 hours. Additionally, after tempering, 40CrNiMoA has a hardness of 280-320HB, resulting in high cutting resistance, with high-speed steel tools lasting only 2-3 pieces per edge, and the cost of tools for a single gear exceeding 1500 yuan.
Customer usage scenarios
To overcome this dilemma, the company has introduced the Kunming Machine Tool TK6513 CNC vertical lathe from Shenyang Machinery Group to build a gear exclusive manufacturing system of "heavy-duty rigid machining+one-time clamping precision turning". The equipment adopts an integral gray cast iron bed body (with a casting wall thickness of 120mm), which has undergone dual stress relief of "natural aging for 18 months+vibration aging for 96 hours". Combined with the gantry crossbeam and box type slider structure, the rigidity distribution is optimized through finite element analysis. The radial cutting stiffness reaches 40kN/mm, which can stably withstand 25kN radial force during 40CrNiMoA cutting; Equipped with Siemens 828D Advanced CNC system and fully closed-loop control of grating ruler (resolution of 0.05 μ m), it achieves ± 0.008mm positioning accuracy and ± 0.005mm repeated positioning accuracy, accurately matching the radial runout requirement of gear ring gear of ± 0.03mm. For high-strength alloy materials, the equipment is equipped with an 18.5kW high-power spindle (maximum speed of 1000r/min) and a high-pressure emulsion cooling system (cooling pressure of 1.2MPa, flow rate of 35L/min), combined with CBN cubic boron nitride cutting tools (hardness HV3000), effectively suppressing tool wear and chip formation.
Gear clamping
In terms of technological innovation, the equipment has achieved a dual breakthrough of "process integration+precision pre control" in gear machining: integrating a Φ 650mm four jaw hydraulic chuck, an 8-station electric turret (tool change time 2.0 seconds), and a radial drilling unit, it can complete gear outer circle precision turning (tolerance IT6), end face milling (flatness ≤ 0.02mm), inner hole boring (cylindricity ≤ 0.01mm), and positioning hole machining (positional accuracy ≤ 0.1mm) in one go. In response to the difficulty of precision control of the gear ring, we innovatively adopt the "reference unified machining method": using the gear blank inner hole as the positioning reference, real-time data of the end face and outer circle are collected through the on machine measurement system (measurement accuracy ± 0.0015mm), and the deformation caused by the weight of the workpiece is automatically compensated (compensation accuracy 0.003mm), so that the radial runout of the gear ring is stably controlled within ≤ 0.04mm. For different module gears (module 8-20mm), the equipment is equipped with 30 sets of process parameter templates, and the replacement time is shortened from traditional 3 hours to 30 minutes.
The implementation results fully comply with the standards for heavy-duty machinery gears: the single piece processing cycle has been compressed from 10 hours to 6 hours, and the daily production capacity has been increased from 8 pieces to 14 pieces; The radial runout of the gear ring gear is ≤ 0.04mm, the end face runout is ≤ 0.03mm, and the surface roughness reaches Ra0.8 μ m, fully meeting the requirements of GB/T 10095.1-2021 "Cylindrical Gear Accuracy System Part 1: Definition and Allowable Values of Tooth Surface Deviation on the Same Side" and ISO 1328-1 standard; The transmission noise decreased from 90dB to 82dB, and the gear meshing efficiency increased by 8%; The tool life has been extended by 200% (up to 6-8 pieces/blade) due to material matching and cooling optimization, and the cost of single gear tools has been reduced to 500 yuan; The intelligent monitoring module equipped on the equipment can real-time collect spindle load (accuracy ± 1%) and cutting temperature (resolution 0.1 ℃), combined with tool wear prediction algorithm, the comprehensive utilization rate of the equipment has been increased from 75% to 93%, and the annual downtime has been reduced by 520 hours.
TK6513 has enabled us to achieve a leap from 'qualified machining' to 'precision manufacturing' of gears. ”The technical director of the enterprise stated, "Our gears have been successfully applied to heavy equipment such as mining machinery and metallurgical equipment. They have not only passed the supplier certification of Liebherr in Germany, but also meet the strict requirements of continuous operation for 15000 hours without faults, which has won us core competitiveness in the gear market." This case confirms that CNC vertical lathes have become a key equipment in the gear manufacturing field to break through the bottleneck of accuracy and efficiency through the deep integration of "heavy-duty rigid architecture+precision closed-loop control+process integration innovation".
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