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燕山大学本科生毕业设计(论文) 附录3外文文献Design of Movable Gantry CNC Milling MachineZHANG JianAbstract: this paper describes the nc milling roller, the overall design and analyses the bilateralsuper-modulus gear pair of driving mechanism of the main points of design,installationguidesurface of the X axis is introduced in this paperKeywords: mobile nc milling designThis machine is mainly used for metal parts of the plane and inclined plane work. It has enough rigidity, Milling head adopts milling head in Taiwan, Milling head with flexible, Spindle motor is frequency conversion motor. It can undertake stepless speed, Ensure accuracy of machine tools and machining precision has good stability, This machine is of high efficiency and exercise,For convenience, make the drive more reliable and convenient in maintenance, less consumption, beautiful modelling, etc, widely used in mechanical manufacturing industry.This paper described the mobile CNC milling refers to longmen framework Vertical milling movement. The biggest advantage of milling roller is (1) Machine cover an area of an area small. Workbench mobile Longmen milling machine, complete machine must be higher than vertical stroke length two times. However, Workbench mobile Longmen milling machine, The length of side frame which is fabricated according to add only longitudinal travel width, The dynamic response of the machine is good. Workbench mobile Longmen milling machine adopts fixed table. The whole cast out with bed, Longmen framework of longitudinal motionDrive torque equivalent unchanged, It is not because of bearing the weight of the workpiece changesChange, so as to ensure the accuracy and performance of the machine tool.The independent design mobile nc Longmen milling(FIG 1)has been a special machine to use. It can satisfy the large castings, steel parts boring and milling, drilling, etc multiple operation process. It is right milling head, It also can process the 4 side of workpiece. The goal of the main design parameters such as Longmen milling under: workbench area 1800mm 4000mm, The travel for X axis:4000mm The travel for Y axis:2000mm The travel forZ axis:750mm, Spindle power 18.5KW, Each axis rapid federate 10m/min.Figure 1 Mobile nc milling1. Mechanical parts designThe bed include Bed, Slide, Longmen frame spindle box, Three axis to drive mechanical parts and related CNC servo part, Now ,The design process is emphasized as follows: The bed is the basic design work, The size of the bed of the design affects the complete machine design. And the rationality of the design of directly affect the whole Machine stiffness. The cross-section shape for the bed like ,(FIG 2) The plane is working on a bed of mesa design has 9 T shaped groove. For the convenience of bed and working mesa of pure dig imageT processing, groove tank completely, The right and left two concerning the design has a long narrow swing plane. It is used to linear rolling guide vice, The author put rail surface design in the two side bed. The main consideration of force transmission directions and unloading, Because the bed will be dragon framework of gravity, cutting force and the gravity of the workpiece, This design can directly into the gravity of longmen framework to machine tools, and Bed only suffer the gravity of the workpiece. The bed by the following basic wall thickness determine By the following formula. C=1/4(2L+B+H)Type: C,L,B is respectively for bed length, width and height of size and unit for the m. Based on equivalent size c, Consulting relevant form,Take the basic wall thickness is 38mm,Figure 2 Shape of concerning the cross-section Spindle box adopts 300 mm 300 mm section design. The torsion bending capacity are stronger. Spindle gearboxes USES two gears Gear sliding speed-change mechanism.It can adapt rough machining requirements. Spindle unit adopts four supporting structure, Ahead three groups of Angle contact ball bearing used to withstand cutting force. Spindle end a deep groove ball bearings are used to unloading, That is not of the Sliding gears of the additional moment. Longmen framework used integral frame which is fabricated according to the design concept, It took about beam and column design into a whole. Although make casting and assembly adjusting difficulty, the whole framework of longmen rigid better, more important is to slide have assembled spindle box, etc. Slide is designed in the frame which is fabricated according to the geometrical dimensions and spindle box, According to the center axis of the guide bar as far as possible to face for the principle, The Z axis and the driver installation position in design, effectively reduce the weight of the slide. Designed to drive into the idea as follows, The X axis to driveUse the bilateral super-modulus gear pair aggravating preloading linear rolling guide vice.X axis and Y axis uses big diameter ball screw preloading vice hardened guide. Rail sliding parts attached engineering plastics, It avoids low when crawling phenomenon, and guide the design is inclined with adjustable device. This machine design make the whole machine to coordinate performance. The axis of the feeding speed and force get the optimal matching. Due to the longitudinal axis machine movement X, and is moving longmen framework of longmen framework weighed 10T, so the linear rolling guide rails to must choose.Because the ball rail system of small friction coefficient, very suitable for longmen framework of moving rigidity requirement.Guide the slider choose one type, each slide block dynamic load can achieve 10t. Considering the safety coefficient, every guide installation 2 slider. Longmen framework for the driver bilateral super-modulus gear pair (see chart 2), feed movement by 3 input, through two inclined gear motor shaft/and axis to 2, and then by two gear - and to drive rack. And thus promote longmen framew3 the helical gear axle spiral of the two opposite directions. Through the spring in the shaft on a three axial force F, make the helical gear trace of axial movement produced at 1 and 2 and axial shaft in the opposite direction Angle of small, round 4 and 5) respectively, the gear tooth surface with two rack, eliminate the gap. 1.2.3- axis 4.5- RackFigure 3 Bilateral super-modulus gear pairSpindle box and vertical motion Z axis adopts ball screw assembly transmission. Because of this machine is not high speed milling machine, the Z axis of the feeding system for servo motor through the ratio of 4 for parallel axis set than gearbox drives the ball screw rotation. In the design of special attention to the Z axis of safety problems. First choose the servo motor with electromagnetic brake, second in the ball screw with a two-way overrunning clutch, prevent ball nuts rotation caused spindle box mechanical prolapse. Of course, in order to protect the z-axis feed institutions, but also in the accuracy with two balance on the slide cylinders. Balance Q, etcThe quality of parts in spindle box 85%.Spindle box around move for the Y axis, in order to guarantee the precision Y axis, and only by their level of ball screw and axial force, servo motor and the ball screw straight league. The author selects the coupling with overload protection device, in the overload when coupling automatically.2 Selection of CNC system The Siemens numerical control system is adopted, because this system 840D provides longmen shaft synchronization function. Use this function, the machine can to dragonsDoor frame for shaft (into) no, X2 clamps its X1 mechanical deviation of displacement. The actual value can exercise for comparison, even the smallest deviation can be corrected, and therefore improve the accuracy of the X axis movement3 EpilogueThe author finally, according to the professional machine parts manufacturers to provide design samples design will reach the twice the result with half the effort. In The design process, the author of CNC system, spindle unit, gearbox, super-modulus gear and ball screw guide etc. According to the sample of empirical formulas, not only shorten design time, make the higher reliability. At the same time we must pay great attention to the timely design machine tools, such as the application of three-dimensional software components immediately after the establishment sketches for 3d model, through the assembly interference, machine avoid collisions occur when in assembly Wade rework phenomenon.翻译移动式数控龙门铣床的总体设计张坚摘要:阐述了移动式数控龙门铣床的总体设计,并重点分析了双边齿轮齿条副驱动机构的设计要点,对X轴的导轨安装面作了介绍。关键词:移动式 数控龙门 铣床设计本文所述的移动式数控龙门铣床是指龙门框架作纵向移动的龙门铣床。移动式龙门铣床的最大优点是:(1)机床占地面积小。工作台移动式龙门铣床,整机长度必须两倍于纵向行程长度,而移动式龙门铣床的整机长度只需纵向行程加上龙门架侧面宽度即可。(2)机床的动态响应好。移动式龙门铣床采用的是固定工作台,一般与床身整体铸出,龙门框架纵向运动的驱动力矩等值不变,不会因工件的承载重量的改变而变化,从而保证了加工精度和机床的响应性能。笔者独立设计的移动式数控龙门铣床(图1),现已作为专机投入生产应用,能满足大型铸件、钢件的镗、铣、钻等多工序加工;配上直角铣头,还可对工件的个侧面进行加工。由于设计思想正确,配套零部件质量过关,该机床各项指标均已达到数控龙门铣床相关国家标准的要求。该龙门铣床的主要设计参数如下:工作台面积为1800mmX4000mm,X轴行程为4000mm,Y轴行程为2000mm,Z轴行程为750mm,主轴功率18.5KW,各轴快速进给为10m/min。1.机械部分设计整机分为床身、龙门架、滑台、主轴箱、三轴进给驱动机构机械部分及相关数控伺服部分。现把设计过程中的重点阐述如下:床身是本次设计工作的基础,床身的尺寸设计影响着对整机的设计,而且设计的合理性直接影响到整机的刚度。床身的截面形状为形(图1)。床身的上平面即工作台面设计有9条T形槽,为方便床身工作台面和T形槽的精刨加工,槽完全贯通。床身的左、右两下脚各设计有一个狭长平面,用来安放滚动直线导轨副。笔者把导轨面设计在床身的两下侧,主要是考虑力的传递方向与卸荷问题。因床身会受到龙门框架的重力、切削力和工件的重力,这样的设计可使龙门框架的重力直接传入到机床的基础上,而床身只受到工件的重力。床身的基本壁厚由以下公式初定:C=1/4(2L+B+H)式中:L. B. H 分别为床身的长、宽、高尺寸,单位为m。根据当量尺寸C,查阅相关表格( 略),取基本壁厚为38mm。主轴箱采用.300mmX300mm 截面设计,其抗扭抗弯能力更强。主轴变速箱采用两档滑移齿轮变速机构,可适应粗精加工需求。主轴单元采用4支承结构,前面三组角接触球轴承用来承受切削力,主轴尾部一个深沟球轴承用来卸荷,使主轴不受到滑移齿轮产生的附加力矩的影响。龙门框架采用的是整体龙门架的设计概念,即把横梁与左右立柱设计成一体,虽然使铸造和装配调整时的难度加大,但整体龙门框架的刚性更好,更重要的是使主轴箱、滑台等部件有了装配基准。滑台的设计是在龙门架和主轴箱的几何尺寸确定后,按照主轴的中心尽量贴近横梁上的导轨面为原则,并把Z轴驱动安装位置设计在滑台上,有效地减轻了滑台的重量。设计进给驱动机构的构思如下:X轴的进给驱动机构采用双边齿轮齿条副加重预压滚动直线导轨副,Y轴与X轴采用大直径预压滚珠丝杠副加硬导轨副,且导轨滑动部分贴有工程塑料,避免低速时产生爬行现象,而且导轨部分设计有斜镶条可调装置。这样设计使机床的整体进给性能得以协调,各轴的进给速度和进给力得到了最佳匹配。由于机床的纵向运动X轴是龙门框架移动,而龙门框架重达10t,所以导轨必须选用直线滚动导轨。因为滚动导轨副的摩擦系数小,非常适合龙门框架移动的动静刚度要求。导轨的滑块选用加长加宽型,每个滑块的动载荷可达到10t。考虑到安全系数,每根导轨安装3个滑块。龙门框架的驱动源为双边齿轮齿条副(见图3),进给运动由轴2输入,通过两对斜齿轮将运动传给轴1和轴3,然后由两个直齿轮4和5去传动齿条,从带动龙门框架移动。轴2上两个斜齿轮的螺旋线的方向相反。通过弹簧在轴2上作用一个轴向力F,使斜齿轮产生微量的轴向移动,这时轴1和轴3便以相反的方向转过微小的角度,使齿轮4和5分别与齿条的两齿面贴紧,消除了间隙。主轴箱的上下垂直运动Z轴采用滚珠丝杠副传动。由于本机床不是高速铣床,Z轴的进给系统为伺服电动机通过传动比为4的平行轴定比齿轮箱带动滚珠丝杠旋转。笔者在设计中特别注意Z轴的安全问题。首先选用带电磁刹车的伺服电动机,其次在滚珠丝杠上装有一双向超越离合器,防止滚珠螺母自转引起主轴箱机械式下垂。当然,为了保护Z轴进给机构的精度,还在滑台上装有两个平衡油缸。平衡力Q等于主轴箱部件质量的85%。主轴箱的左右移动为Y轴,为了保证Y轴的传动精度,并使丝杠只受水平轴向力,故采用伺服电动机与滚珠丝杠直联方式。笔者选用的联轴器带有过载保护装置,在过载时联轴器会自动脱开。2.数控系统选型数控系统采用的是西门子840D,因为此系统提供了龙门轴的同步功能。使用此功能,本机床可以对龙门框架进给轴(X1,X2)实现无机械偏差的位移。运动的实际值可进行连续比较,即使最小的偏差也可以得到纠正,因此提高了X轴的运动精度。3.结语笔者最后要说明的是,根据专业机床零部件厂商提供的设计样本进行设计会达到事半功倍的效果。在此次设计过程中,笔者对数控系统、主轴单元、变速箱、齿轮齿条和丝杠导轨等都按照样本上的经验公式得出,不仅大大缩短了设计时间,同时使设计的可靠性更高。同时在设计机床中要注重适时应用三维软件,如在部件草图确立后就应立即进行三维模型装配,通过进行装配干涉检查,避免机床在装配时出现的碰撞干涉返工现象。
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