How slender shaft wear? - Detailed slender shaft grinding
First, the grinding characteristicsGenerally the length and diameter greater than the elongate shaft 10 of the workpiece is called, the rigidity of the elongate shaft is poor, the grinding, the grinding force and the elongate shaft grinding heat prone to deformation under the action; when the workpiece length diameter ratio of more than 40, the deflection of the workpiece's own weight causes the workpiece in the processing of generating the flank, and that leads the surface to be machined defects prime line is not straight. Because of its poor stiffness, grinding process prone forced vibration and self-excited vibration, the surface of the polygonal straight wave and chatter chatter and the emergence of runout. Therefore, the impact accuracy of the main factors grinding the workpiece itself insufficient rigidity and processing grinding force and grinding heat. Grinding slender shaft key is how to increase the rigidity of the workpiece support, reducing the grinding force of grinding heat.Second, the method of grindingGrinding elongated shaft should be in operation and clamping methods to try to reduce deformation of the workpiece, specific attention to the following points:(1) before grinding the workpiece, should increase the straightening and stress relieving heat treatment process to avoid grinding the stress generated due to deformation of the workpiece.(2) a reasonable choice of grinding wheel. Should be selected coarse grain size, hardness, low and narrow width wheel, in order to reduce the grinding force can be wider wheel repair narrower.(3) due to the more blunt grinding wheel greater radial force, the workpiece more prone to bending deformation, there is often necessary to dressing wheel, the geometry of the workpiece in order to ensure accuracy. Rough diamond grinding wheel to use sharp corners, use a larger amount of trimming trimming, grinding process, the wheel should always stay sharp.(4) In order to reduce the workpiece roundness error and vibration, can be double pull lever dial is balanced work force.(5) tailstock top tight on the workpiece grinding than send some extent, so as to prevent the top part of the tightening force caused by the bending deformation of the workpiece can be reduced because the grinding caused by thermal deformation elongation bending.(6) using the center frame support. The number should be more center frame length and diameter of the workpiece is determined, see Table 3.1-1. Installation should pay attention to the center frame support center coincides with the center of the workpiece. In order to ensure an ideal cylindrical workpiece carrier surface contact, should be pre-grind the workpiece support at short cylindrical support, and to leave grinding margin, must be randomly bed processing. Production support round the merits, will directly affect the slender shaft machined dimensional accuracy. Then adjust the center caught in the support block, gently touch the surface, when the length of the workpiece supports access knife round and polished, with the continuation of the workpiece diameter grinding small, need to be adjusted center frame, the support circle after grinding proceeds runout deviation between 0.02 ~ 0.03mm. After grinding grinding stage requires the support of a circle runout is less than 0.005mm.Figure 3.1-1 is M1432A grinder common center frame. Is shown in Figure 3.1-1a open-center frame, is the most commonly used grinding elongate shaft support tool supported at two points of its structure, the use of its horizontal and vertical supporting pawls supporting pawls on the workpiece and the grinding wheel together constitute the three o'clock point on the workpiece support circle. Figure 3.1-1b shows a claw-type center frame, when used with a circumference of three supporting claw uniform paired together around the workpiece support circle. Regardless of what form the center of the frame support the workpiece, the workpiece should be used with the first requirement to ensure the support constituted by supporting pawls center coincides with the rotational center of the workpiece.(7) the grinding process, the coolant should fully.(8) should work fine grinding Eve after straightening and stress relieving treatment to reduce the workpiece bending stress,
(9) the workpiece center hole should be lapped. In order to reduce the top center hole and the friction between the grinding process Haiyao often add oil.(10) a reasonable choice of grinding parameters, such as turning of the workpiece caused by bending, so do intermittent grinding wheel, so the first few depth of cut and feed to be small, to reduce the grinding force. Workpiece speed can be selected to be lower, in order to avoid grinding vibration. Coarse grinding, Us = 30m / s, Uw = 15m/min, ap = 0.01 ~ 0.02mm, ufa = 1 ~ 2m/min; refined friction when, us = 15 ~ 20m / s, uw = 10m/min,Ap = 0.002 ~ 0.005mm, ufa = 0.3 ~ 0.5m/min, the final number should be increased by light grinding. Grinding length from the elongated shaft considered available near both ends of the larger axial feed rate, near the middle, the feed speed is slower, and appropriately increase the number of passes.Third, grinding instances
Workpiece as shown in Figure 3.1-2
Processing steps:(1) The workpiece aging.(2) cleaning and polishing both ends of the workpiece center hole, wipe the hole after greased.(3) Install the workpiece, the grinding method using pre-cut parts of the support Tama Center cylindrical frame, clamping cylindrical ends before the need to find positive radial circular runout error <0.01.(4) Adjust the center frame, when the workpiece support round grind, the center frame supported on the support surface on the center portion of the support frame supporting a direct impact on the accuracy of the elongate shaft grinding quality, so installation should help carefully adjusting dial, which method is:The touch dial indicator to the workpiece 45 ° to the vertical axis of prime line, rotating the workpiece and rotating the corresponding knob, the upper support block just contact the workpiece support circle (monitoring the amount of variation in the table), adjusting dial 0 , turn the knob under the support block, so that the workpiece center moves upward 0.02mm, while turning the knob support block, allowing the center to the workpiece support block Dumbo wheel movement, dial indicator changes in value 0.025mm. The vertical cylindrical pillow block close to the ground surface, horizontal pillow block pressure not too much, just gently touch can not loose.(5) coarse outer, left margin 0.2mm.(6) straightening workpieces aging treatment.(7) Adjust the center frame. As the grinding depth, the bracket requires constant adjustment of the support block, so that the support has to maintain accurate precision. Herbs on the workpiece during grinding each position size and radial runout is measured according to the measurement results in order to adjust the corresponding supporting block.