注塑机拉杆梯形螺纹端卸载槽的多目标优化

Multi-objective Optimization of Slot for Releasing Stress of Trapezoidal Thread End of Tie Bar of Injection Machine

在用ANSYS软件对近卸载槽处梯形螺纹进行有限元分析的基础上,就拉杆梯形螺纹端卸载槽的几何特性建立其参数优化模型,以控制梯形螺纹在近卸载槽附近的最大应力、卸载槽的最大应力以及卸载槽加工量最小化为统一的目标函数。通过对拉杆在单向拉伸力作用下的多目标优化,使应力适当集中在拉杆卸载槽处,其最大应力比平均单向拉伸应力提高20%,拉杆梯形螺纹牙根在卸载槽处的最大应力降低52%,使卸载槽能够较好地发挥其卸载的作用。在偏载作用下,拉杆梯形螺纹牙根在卸载槽处的最大应力降低11.6%;并以优化结果为依据,分析了拉杆出现较大附加弯矩的原因。

Aimed to the premature the failure of the trapezoidal thread near the releasing slot of the tie bar of injection machine, the stress distribution of the trapezoidal thread and its adjacent slot of the tie bar were analyzed by means of finite element method of ANSYS software, and the parameter model for the optimization according to the geometry characteristic of the slot adjacent trapezoidal thread of a tie-bar was built up. Multi-objective function was used to reduce the maximum stress of a trapezoidal thread and to control the maximum stress and the minimum machining allowance of its adjacent slot of the tie bar. Through the multi-objective optimization of the parameters of the tie bar under the condition of simple tension, the maximum stress of the slot of the tie bar increased 20% in comparison with the average simple tensile stress and the maximum stress on the root near the slot of the trapezoidal thread of the tie bar decreased 52%, which made the slot play a better role in stress releasing. Under the condition of deflective load, the maximum stress on the root near the slot of the trapezoidal thread of the tie bar decreased 11.6%. According to the results of optimization, the reasons for the larger appending moment of force in the tie bar were brought forward.