Numerical Simulation of Transient Temperature Field and Stress Field in Grinding of HVOF WC-10Co4Cr Coating
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摘要: 从经典热传导方程和热弹塑性力学出发,建立了磨削过程中移动热源作用超音速火焰喷涂WC-10Co4Cr涂层材料的二维传热模型和热应力模型;在考虑材料热物理参数随温度变化的基础上,利用有限元分析软件ANSYS来研究双层材料在磨削热-结构耦合作用下的瞬时温度场和应力场。数值研究结果表明,由于WC-10Co4Cr涂层热传导系数和比热容比300M钢基体大,所以温升主要停留在涂层内;磨削温度沿工件深度方向非连续分布,涂层基体结合面的温度梯度最大;由于涂层、基体材料热膨胀系数差异较大,在结合面处产生极大的热应力;磨削温度、涂层-基体结合面热应力随涂层厚度的降低而增大。开展了磨削温度测量实验,测量了不同涂层厚度时工件表面的磨削温度,对数值仿真结果进行了验证。Abstract: Based on the classical heat conduction equation and thermoplastic mechanics, the two-dimensional heat transfer model and thermal stress model for the grinding process of High Velocity Oxygen Fuel (HVOF) WC-10Co4Cr coating under the action of moving heat source were established. On considering the temperature dependent material properties, the transient temperature field and thermal stress field were simulated via finite element method. As the thermal conductivity and specific heat capacity of WC-10Co4Cr are larger than 300 M, the temperature rise mainly stays in the coating. The grinding temperature is discontinuous along the depth direction of the workpiece, and the temperature gradient of the coating/substrate junction surface is the largest. Due to the large difference in thermal expansion coefficient between the coating and the substrate, the great thermal stress is generated at the bonding surface. The grinding temperature and thermal stress of the coating/substrate junction surface increase with the decreasing of coating thickness. The grinding temperature experiments were carried out, the surface grinding temperature with different coating thicknesses was measured and the simulation results were compared with those experimental. A good agreement was found between the FEM results and the experimental.
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Key words:
- grinding /
- HVOF coating /
- FEM /
- Grinding temperature field /
- grinding stress field
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表 1 砂轮性能参数[15]
材料 密度ρ/
(g·cm-3)导热率λ/
(W·(m·K)-1)比热容c/
(J·(kg·K)-1)树脂 1.25 0.125~0.7 1 591~1 758 金刚石 3.515 2 000 1 827 表 2 工件热物理性能[16]
物理性能 300M钢 WC-10Co4Cr 密度ρ/(g·cm-3) 7.74 15.5 导热率λ/(W·(m·K)-1) 0.016 1T+21.814 121 比热容c/(J·(kg·K)-1) 0.296T+466.714 800 弹性模量E/GPa 198 71 泊松比μ 0.32 0.3 线膨胀系数α(10-6/K) 13.4 4.3 表 3 磨削参数及磨削结果
实验
序号砂轮线速度
vs/(m·s-1)工件进给速度
vw/(mm·min-1)磨削深度
ap/mm切向磨削力
Ft/N热分配比
Rw/%涂层厚度
h/μm磨削温度
T/℃339.74 330 1 90 2 100 0.04 40 33% 339.74+2ap 304 339.74+4ap 270 233.57 482 2 90 2 800 0.06 66 33 233.57+2ap 420 233.57+4ap 355 435.29 287 3 150 2 800 0.02 23 37 435.29+2ap 261 435.29+4ap 242 424.68 426 4 150 3 500 0.04 44 36 424.68+2ap 368 424.68+4ap 337 -
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