【作者】 刘红奇；

【导师】 李斌； 唐小琦；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2008， 博士

【摘要】 数控加工的过程中,切削力等复杂的物理因素影响加工质量、效率和安全,而现在普遍的数控技术还只限于几何运动控制,对这些复杂的物理因素则还未涉及。自适应加工技术是研究对这些因素进行控制的技术,目前存在一些还未解决的难题,主要有切削负荷在线准确测量、加工过程的控制策略以及智能自适应加工技术的实现方法等。基于此,本文对数控机床自适应加工技术进行了深入的研究,具体的研究内容主要包括以下几个方面:首先,基于对伺服进给系统和主轴系统的分析,建立了进给和主轴系统的数学模型,可在给定负荷变化的情况下,对电机响应时的驱动电流变化进行预测。通过实验分析了主轴电流对切削负荷的响应特性,该特性对准确间接测量切削负荷具有重要的意义。第二,在铣削加工机理分析的基础上,给出了不同切削参数的条件下,切削力的预测模型。此外建立了切削试验平台,通过实验分析了实际切削过程中切削参数对各切削力分量的影响,说明了合理参数选择的重要性,为自适应加工提供相应的控制规则。第三,提出了一种可在生产车间条件下对切削力模型快速、经济的标定方法。该方法利用液压装置来模拟切削过程中产生的切削抗力,而力大小可通过调整该系统的参数进行控制。研制了基于该标定方法的标定装置。进而,建立了标定装置的BP神经网络模型。标定装置的验证试验结果表明该方法有效,该标定装置既可充当测力仪,又可提供用于标定的切削抗力,并无需通过切削来进行标定,节约了资源。此外,建立了基于电机驱动电流的切削力和切削扭矩的间接测量模型,模型考虑了切削力之间相互影响,提高了基于电流测量切削负荷的测量精度。第四,基于模糊控制理论,设计了加工自适应控制过程中的二维模糊控制器,并利用切削机理对控制量进行预测,提出了预测与模糊控制相结合,以及粗、精控制相结合的控制策略。该控制策略提高了对加工过程控制的稳定性,能更好地满足切削工艺学的要求,为数控机床自适应加工提供控制策略和方法。第五,构建了基于PC104的硬件平台,并开发了基于DOS操作系统的实时自适应控制软件系统,通过对这两者的集成,研制了外挂式的自适应控制装置。该装置与管理服务器进行连接,组建了基于以太网的自适应控制网络系统,实现集中车间级或者更大范围的数控机床的监控。该装置已装备于东方电机股份有限公司的五轴联动机床,取得了较好的应用效果。最后,研究了数控系统与自适应加工技术的集成方法。提出了利用数控系统开放的PLC资源的集成方法,通过二次开发,实现了集成于七轴五联动数控系统的智能自适应控制功能,并应用于螺旋桨叶片等复杂零件的加工过程控制,控制效果明显。更多还原

【Abstract】 In the NC machining process, complicated physical factors, such as cutting force, influence the machining quality, efficiency and safety. At present, the ordinary NC technology focuses on geometrical motion control only without considering the effect of physical factors. Although adaptive processing technology could cope with the issue of the physical factors, there are still some unresolved problems, such as accurate on-line measurement of cutting load, process control strategy, as well as the realization methods of adptive control. In this dissertation, research on adaptive processing technology in the NC machine tool has been conducted deeply. The main work and contributions are as follows:Firstly, the model of spindle system and servo feed system have been proposed. It can forecast the variation of drive current under the different given loads. Experiment results show that the above response characteristics are of significance to the indirect accurate measuring of cutting load.Secondly, based on milling mechanism, the forecasting models of cutting force and torque have been established under different cutting parameters. The cutting experimental platform has been built. The influence of cutting parameter on cutting force was analyzed experimentally. It can be found that reasonable cutting parameters were very important for adaptive control of process.Thirdly, a new economic fast calibrating method of the relationship between cutting force and feed current has been put forward, by which a set of hydraulic device was employed to simulate the cutting resistance. The value of the simulation cutting resistance can be controlled by adjusting the hydraulic system parameters. Based on the method mentioned above, the calibrating equipment is developed, and corresponding BP neural network is formulated. The experiment results validate the mechanism of calibrating equipment. The calibrating equipment can act as dynamometer without the calibrating cutting experiments. Furthermore, an indirect measurement model based on motor current has been established considering the relationship between the cutting force and torque. This model has improved the measurement accuracy and is an effective on-line measurement method of cutting load in the adaptive control of cutting progress.Fourthly, based on fuzzy control theory, two-dimensional fuzzy controller used in the adaptive control of process has been designed, which applies the strategy of the combinations of rough and precision control, and the forecasting and fuzzy control are applied. The control strategy can raise the stability of the adaptive control progress and better fulfill the request of the cutting process.Fifthly, the hardware platform based on PC 104 has been set up, and the real-time adaptive control software system has been developed. The adaptive control plug-equipment has been developed through integration of the two parts above. The equipment is connected to management server based on Ethernet, and the adaptive control network system is built. The centralized monitor of NC machine tools has been realized. The plug-equipment has been adopted in five-axis machine tools satisfactorily.Finally, the integrated method of NC system and adaptive processing technology is investigated. The integration of NC system and adaptive control is realized through secondary development, which makes use of PLC of NC system. The adaptive module of open CNC system is develped, which has undertaken the function of the 7-axis NC system. The case study on the procession of propeller blades has been conducted, and its application results are remarkable.更多还原