A method for heat treating a nodular cast iron crankshaft of an automated fog cooling device

By using an automated mist cooling device to monitor and dynamically adjust spray parameters in real time, the problem of unstable cooling of ductile iron crankshafts was solved, resulting in the refinement of the pearlitic structure and the improvement of mechanical properties, ensuring the high strength and toughness of the crankshaft.

CN122105092APending Publication Date: 2026-05-29KUNMING UNIV OF SCI & TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
KUNMING UNIV OF SCI & TECH
Filing Date
2026-03-17
Publication Date
2026-05-29

AI Technical Summary

Technical Problem

The existing mist cooling process for ductile iron crankshafts cannot monitor the cooling rate in real time, resulting in unstable cooling and an inability to accurately control the morphology of pearlite microstructure, which affects mechanical properties and poses a risk of large pearlite lamellar spacing or martensite formation.

Method used

An automated mist cooling device is adopted, combined with an industrial control computer and an infrared temperature measurement system, to monitor the crankshaft temperature in real time. The spray parameters are dynamically adjusted through a PID algorithm to achieve three-stage mist cooling control, ensuring that the cooling rate is precisely adjustable within the range of 4-7℃/s, thus avoiding uneven cooling and stress concentration in the structure.

Benefits of technology

It achieves finer pearlite lamellar spacing, improves mechanical properties, tensile strength ≥1050MPa, elongation ≥5%, hardness ≥300HV, significantly improves the matching of material strength and toughness, and ensures product quality stability and consistency in mass production.

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Abstract

The application discloses a nodular cast iron crankshaft heat treatment method of an automatic mist cooling device and belongs to the technical field of nodular cast iron heat treatment.The method can solve the problems of unstable performance and the fact that the cooling speed of the existing mist cooling process cannot be controlled in real time, can collect the crankshaft temperature in real time, and can dynamically adjust the spray parameters.The heat treatment method comprises the following steps: melting, spheroidizing and inoculation, molding and pouring, austenitizing, precise mist cooling and tempering.Through the device, continuous gradient heat treatment of the nodular cast iron crankshaft can be realized, the cooling rate (4-8 DEG C / s) of the pearlite transformation interval can be automatically controlled, the proportion of the pearlite + ferrite structure can be controlled, and the pearlite lamella spacing (less than or equal to 135 nm) can be refined.The application realizes closed-loop control in the cooling process, dynamically adjusts the cooling rate to refine the structure, improves the mechanical properties (tensile strength greater than or equal to 1050 MPa, elongation greater than or equal to 5%) of the crankshaft, reduces batch fluctuation, reduces the cracking risk, the water resource recovery rate is greater than or equal to 90%, and is suitable for batch production.
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