The Method Of Improving Lathe Machined Accuracy

In the automobile manufacturing industry, the cutting of transmission spline shafts, the machining of axle gears and transmission gears occupy a very important position. Traditional spline and gear milling machines have slower cutting speeds and lower accuracy during spline and gear machining. In order to improve machining efficiency, many companies have adopted CNC high-efficiency spline milling machines to process spline shaft components. This type of machine tool can process various standard forms of splines, gears, step gears and splines, taper gears and splines. For example, if an enterprise adopts YKX6012 CNC high-efficiency spline milling machine, the effective length of the spline is 77mm, the speed of the spline hob is 300r / min, and the machining time of a product is: t machine = (L + l) Z / S0 × n) = (77 + 5) × 22 / (1.8 × 300) = 4.07min, t single = t machine + t auxiliary = 4.07 + 1 = 5.07min; and the unit production time of ordinary spline milling machine is 22.78 min. 22.78 / 5.17 ≈ 4.4 (times). From this, it can be seen that the production efficiency of the CNC high-efficiency spline shaft milling machine can be increased by more than 4 times than that of ordinary spline shaft milling machines.
The accuracy of the horizontal spindle of the CNC lathe plus the machine tool spindle box and the vertical spindle on the base determines the accuracy of the screw being processed. At the same time, when the screw rotates at a high speed of several thousand revolutions in the compressor, the screw with poor accuracy will Make the compressor generate heat, vibration, low efficiency, fast wear and other phenomena. At present, there are roughly two schemes for the spindle structure of the existing single screw machining machine tools in China.
The first type: the main shaft structure with unadjustable radial radial bearing
The front bearing of the main shaft uses a combination of a double-row cylindrical roller bearing and two thrust ball bearings. The main shaft uses a double-row cylindrical roller bearing to bear the radial cutting force, and uses two thrust ball bearings to bear the axial cutting force. The main shaft rear bearing generally adopts a double-row cylindrical roller bearing or a radial ball bearing. The advantages of this spindle structure are simple machining and assembly of the spindle, and low cost.
Second type: Spindle structure with adjustable radial clearance of bearing
The main shaft front bearing adopts a double row cylindrical roller bearing with P4 grade tapered bore and a double row radial thrust ball bearing with P4 grade. The spindle uses a double-row cylindrical roller bearing with a tapered bore to withstand radial cutting forces, and a double-row radial thrust ball bearing withstands axial and partial radial cutting forces. The main shaft rear bearing generally uses a P5 double-row cylindrical roller bearing with tapered bore.
The inner ring and the matching shaft diameter of the double-row cylindrical roller bearing with a tapered bore are both 1:12 conical. Locking the bearing with a round nut will cause the bearing to move in the axial direction and expand the inner ring of the bearing to reduce or eliminate it. Purpose of bearing radial clearance.

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