【作者】 张杰；

【导师】 张世伟；

【作者基本信息】 东北大学 ， 流体机械及工程， 2015， 硕士

【摘要】 无油螺杆真空泵具有抽速范围宽、结构简单紧凑、抽气元件(等螺距或变螺距螺杆转子)无摩擦、振动小噪音低、使用寿命长以及无油污染等诸多优点,已被广泛应用在半导体、医药、粮食干燥、化工制药、有色金属冶炼等众多工业领域中。因此,无油螺杆真空泵是符合世界经济发展和节能减排潮流的“绿色”真空泵。但是,由于国内制造技术相对比较落后,使得核心元件螺杆转子的加工一直是个难点,导致国内无油真空螺杆泵行业发展缓慢,且大部分产品都要依赖进口。目前,关于无油螺杆真空泵螺杆转子的加工越来越受到各研究单位以及企业的关注,因此,对螺杆转子加工方法的研究是必要的,也是符合当前行业需求的。本课题针对无油螺杆真空泵螺杆转子的加工问题,从成型铣削加工和五轴数控加工两种机械加工方法出发,对螺杆转子的加工进行了研究和分析。研究螺杆转子的成型铣削加工,是以等螺距螺杆转子为被加工对象展开的。首先分析了采用成型铣刀加工螺杆转子的加工原理和过程,确定实现螺杆转子成型铣削加工的关键是设计相应的成型铣刀。通过对螺杆转子的螺旋面进行解析分析,得到其法线各分量方程;对转子坐标系与铣刀坐标系进行坐标变换,利用转子螺旋面法线与铣刀圆切线间的垂直关系建立了转子螺旋面与铣刀回转面在转子坐标系下的接触线条件式;依据接触线条件式求解出确定铣刀廓形的参数组(t,τ)表达式;然后通过进一步推导,计算出成型铣刀廓形在铣刀坐标系下的理论方程形式。最后以等螺距凹齿面螺杆转子为例,对其采用成型铣削加工方法完成的开槽过程进行了研究,并设计出其开槽铣刀。五轴数控加工是一种通用的加工方法,能实现无油螺杆真空泵用各种齿形的等、变螺距螺杆转子的加工。论文对加工螺杆转子所用的数控机床和刀具进行了确定,对加工过程中的切削用量以及其他参数进行了分析和计算。然后分别以等螺距凹齿面螺杆转子(已用开槽铣刀完成开槽)和变螺距双摆线凹齿面螺杆转子为例,分别对等、变螺距转子的加工阶段作了具体的规划和分析,然后对各加工阶段的加工曲面进行了加工区域的划分,并利用UG软件创建了各加工区域的加工工序,从而得到各加工区域的刀具轨迹。为验证五轴数控加工方法的可行性,利用VERICUT仿真软件对螺杆转子的加工过程进行加工仿真。在VERICUT仿真环境中创建了数控机床运动模型、毛坯模型和加工刀具,并添加了刀具轨迹,然后对等螺距和变螺距螺杆转子的加工过程进行仿真,得到了等、变螺距转子的仿真结果。本论文在推导成型铣刀廓形方程的过程中,不涉及到具体的转子型线;而对于用五轴数控机床加工螺杆转子的方法则具有通用性。因此,本论文所探讨的两种加工螺杆转子的机械加工方法不受转子型线的限制。更多还原

【Abstract】 The oil-free screw vacuum pump has been widely used in industrial areas of semiconductor,medicine,grain drying,chemical and pharmaceutical,spatial simulation,and many other industries,which was due to its lists of advantages,such as wide pumping speed range,simple and compact structure,no friction between the pumping component(screw rotors of the fixed lead or gradational pitch),and no oil pollution,and so on.So,the dry screw vacuum pump is also an environmental one that suits the development of world economy and energy saving.However,the machining for screw rotor is always a challenge,as the manufacturing technology falls behind in our country,which leads to the industry of oil-free screw vacuum pump developing slowly and depending on imports.Currently,the machining for screw rotor has gained much more focus from research units and companies.So,it is necessary and desirable to research the processing methods of screw rotor.On account of the machining for screw rotor,this paper mainly analyzes and researches the processing methods of screw rotor based on from milling method and five-axis NC machining method.The fixed-pitch screw rotor is mainly research object when the forming milling method is analyzed in this paper.In this step,the machining principle and process of forming milling method have been learned.And the most important issue is to design formed cutter.In order to design the formed cutter,much work has been done in this paper,including analyzing the helical surface of screw rotor and calculating the normal of it,building relationship between the coordinate system based on screw rotor and the coordinate system based formed cutter,inferring the contacting relation between helical surface of screw rotor and rotative surface of formed surface based on vertical relation between the normal of helical surface and the tangent of formed cutter circle in the coordinate system based on screw rotor.Then the parameters(t,τ)deciding the profile of formed cutter have been solved out.In the end,the article gets the theoretical equation of calculating the profile of formed cutter in the coordinate system based formed cutter.Five-axis NC machining method is a universal processing method,which can perform the machining of various screw rotors.Aiming at getting qualified screw rotor smoothly,the five-axis machine tool and cutting tool have been confirmed,cutting parameters and other data have been inferred and calculated.Then according to the given fixed-pitch screw rotor(which has been slotted)and the double-thread screw rotor,this paper plans and analyzes the machining stage of screw rotor,divides helical surface to different areas,then establishes manufacturing procedures of every areas based on UG(a CAD/CAM software),at last,gets the cutter paths of every areas.In order to verify the feasibility of five-axis NC machining method,the paper uses VERICUT software to simulate the machining process of screw rotor.In the simulation process,the motion model of machine tool,blank model and cutter tool model have been established,then the cutter path has been added.After these work,this article gets the simulation result of machining screw rotor.Because the process of referring theoretical equation of the profile of formed cutter is not influenced by profile of screw rotor,and five-axis NC machining method has strong universality,so these two machining methods of screw rotor are not confined by profile of screw rotor.更多还原