Rotary table concentricity and horizontal face runout error and the importance of dividing precision

Rotary table and concentricity and horizontal face runout error 2018 - the importance of dividing precision 08 - 23 xue-xin wang ( Wuhan state of wisdom of seiko manufacturing technology co. , LTD. ) Due to the need of this process, the set the center of the rotary table to Y axis, and the workbench plane set to X axis, dividing precision benchmark set the zero line as X0, dividing ray for Xa, set the workbench plane jumping up and down as X is minus X, as shown in figure 1. Rotary table indexing accuracy and repeat precision first depends on the precision of the rotary table's center Y, Y axial-radial circular runout error is too large will directly affect the precision of indexing, because the center of the circle is not on the same circle, so the Angle of the measured is not accurate, not to mention repeated positioning precision ( Here to talk about is very different from actual measured value and the theoretical value) So the Y axis ( The center of the circle) Is to ensure that the radial precision indexing accuracy and repeat the important foundation of positioning accuracy. If Y axial-radial circular runout is too large, when X0 rotate 180 & deg; To Xa position will be the point O in OX0 and OXa between two lines form a certain Angle, Xa - originally O- X0 is in a straight line, no matter how the workbench rotating this line should always is the most ideal. But due to the deflection of the point O the straightness is not ideal. Here if you want to achieve ideal deflection of straightness is only O point as small as possible, in the processing box the coaxial bearing hole on the two opposite can produce such a situation. Kong Xian X0 surface machining, cutting head stationary, rotary table through the machine table to the horizontal direction of movement of the cutting tools on the surface of the finished feed processing X0, workbench back to turn the rotary table to spin the Xa to X0 processing Xa the hole location, then the displacement due to point O to make relatively motionless on the surface of the tool bit corresponding to the Xa hole center deviation in the horizontal direction, so that the two center of holes in horizontal direction is different, have 0 if the turntable is point O. 01 mm accuracy error, then the two holes in horizontal direction, the maximum circle error can reach 0. 02 mm, similarly if the rotary table platform rotary end jump error is too large, will directly lead to the error of the two hole center high direction, as shown in figure 2, figure 3 and figure 4. Rotary table X ( The workbench plane) The rotation accuracy ( The X is minus X) , Y axis of the radial, repositioning precision indexing precision and accuracy, is to ensure that the spatial coordinates of each axis vertical and parallel important basis, is the important foundation of guarantee, to ensure the machining accuracy of components. Below to automobile engine block machining and gearbox as an example, talk about the X, Y axis precision rotary table, dividing accuracy and repeat positioning accuracy, its influence on the overall machining precision. As shown in figure 5, rotary table and processing process of automobile engine body, assuming that hole 7 ~ 9 holes for a processing feed process, then rotate it 180 & deg; Bore, 5, 6 for another feeding process of machining, hole 1 ~ 4 feeding process of a separate processing respectively. In the process of machining hole 5 and 6 holes, as a result of the rotary table concentricity error and dividing the existence of the error, lead to supposed as Y0X plane parallel hole 6 circle in the horizontal direction with a certain Angle, because of the existence of workbench face runout error can lead to this should be in Z0X planar parallel hole 6 in vertical direction with a certain Angle, which makes the theory should be parallel to the body's four sides in two transverse vertical hole 6 with the surface appeared a certain Angle. Also in the processing of bore hole 7, 8, 9 also can appear the same problem in the process, even for the workbench rotated 180 & deg; After the indexing accuracy and repeat positioning accuracy enough, may lead to greater error. The two machining process step by step, lead to in theory should be parallel to the four sides, two end face bore vertical datum coincidence of 5, 6 not only the central axis and its coincidence, even presents the phenomenon which is not in a straight line. Also bore for 1 ~ 4 processing, in theory should have four hole axis and the vertical and horizontal line parallel to each other, but the existence of the above error, lead to the shaft 1 ~ 4 parallel appear error, and bore it with 5 or 6 axis perpendicularity also can appear the corresponding error. Due to various reasons for error of the machining process, make the machining process and theory of positioning is the corresponding deviation, plus the processing steps, resulting in further enlarge machining error of the parts on the whole, which makes the products on the precision requirement cannot achieve ideal expectations, leading to the performance of the product. From the above analysis, can come to the conclusion that the concentricity error of rotary table, plane rotary error and dividing error is smaller, the space in the coordinate system of each axis perpendicularity, parallelism and alignment. Mechanical equipment is composed of a large number of mechanical parts, especially for some complex of large mechanical equipment but also requires a lot of machinery parts and components, and the machining precision of mechanical parts put forward higher requirements. Single mechanical parts machining accuracy will lead to problems in the assembly process of mechanical equipment in the error accumulation, and ultimately to the processing and manufacturing precision of the mechanical equipment, produce great impact on the quality and use of the service life. In the machining process of the automobile engine airframe, through effectively control rotary table concentricity error, face runout error and indexing error, can significantly improve the space coordinate axis of the engine block and crankshaft bearing hole of the alignment accuracy, so as to improve the power conversion efficiency of the engine, make one unit of fuel or electricity can generate more power output, at the same time also can reduce the wear and tear of spare parts to reduce noise, to prolong its working life. Source: metal processing ( Cold working) 19, 2017