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下死点动态精度是评价压力机性能的重要指标之一,决定着冲压件的冲压质量。在瞬时可靠度理论的基础上建立了高速冲床运动精度可靠性的计算模型,并用瞬时状态矩阵对Monte Carlo模拟方法进行改进和简化。基于改进后的Monte Carlo模拟方法分析了JF75G-300高速冲床在不同速度下制造误差、弹性变形和运动副间隙对运动精度可靠性的影响。仿真结果表明:不同速度下的位移误差均服从正态分布,且随着速度的提高位移误差的波动量增大,运动精度的瞬时可靠性明显降低。通过测量JF75G-300高速冲床不同速度下的下死点动态精度,验证了速度变化对冲床运动精度可靠性影响的模拟结果。以上模拟方法可在设计阶段对冲床的下死点动态精度进行预测,为加工精度、杆件刚度及装配精度的选择和优化提供理论基础。
Bottom dead point dynamic precision is to evaluate the performance of an important indicator of the press, determines the stamping parts of the stamping quality. Based on the theory of instantaneous reliability, a computational model of motion accuracy of high-speed punch is established, and the Monte Carlo simulation method is improved and simplified by using instantaneous state matrix. Based on the improved Monte Carlo simulation method, the influence of manufacturing error, elastic deformation and clearance on the accuracy of motion of JF75G-300 high speed press at different speeds was analyzed. The simulation results show that the displacement errors under different velocities all obey the normal distribution, and as the velocity increases, the fluctuation of the displacement error increases, and the instantaneous reliability of the motion accuracy decreases obviously. By measuring the dynamic accuracy of JT75G-300 high-speed punch at different speeds of bottom dead center, the simulation results of the influence of speed on the reliability of punch accuracy are verified. The above simulation method can predict the dynamic precision of the bottom dead center of the punch during the design stage and provide a theoretical basis for the selection and optimization of machining accuracy, rod stiffness and assembly precision.