The Method For Improving Lathe Machining Parts Precision

CNC lathe machining is currently one of the most widely used machining forms. Compared with ordinary lathes, its machining accuracy is high, and the shape and dimensions of the cnc machining parts are consistent. It can realize one-man multi-machine operation and improve labor efficiency. Reduce the scrap rate and save labor costs.

In the automobile manufacturing industry, the hobbing of the drive shaft spline shaft, the processing of axle gears and transmission gears occupy a very important position. The cutting speed of the traditional spline and gear milling machine is slow in the process of spline and gear processing, and the accuracy is not high. In order to improve processing efficiency, many enterprises have adopted CNC high-efficiency spline milling machines to process spline shaft parts. This type of machine tool can process various standard forms of splines, gears, stepped gears and splines, taper gears and splines. 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 time for processing 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; while the single piece production time of ordinary spline milling machine is 22.78 min. 22.78/5.17 ≈ 4.4 (times), it can be seen that the production efficiency of CNC high-efficiency spline shaft milling machine can be increased by more than 4 times compared with ordinary spline shaft milling machine.

The precision of the horizontal spindle of the CNC lathe plus the spindle box of the machine tool and the vertical spindle on the base determine the accuracy of the processed screw. At the same time, when the screw rotates at a high speed of thousands of revolutions in the compressor, the screw with poor accuracy will Make the compressor produce heat, vibration, low efficiency, fast wear and other phenomena. At present, the existing single-screw processing machine tool spindle structure in China generally has the following two schemes.

The first type: main shaft structure with non-adjustable radial bearing clearance

The front bearing of the main shaft adopts 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 two thrust ball bearings to bear the axial cutting force. The rear bearing of the main shaft generally adopts a double-row cylindrical roller bearing or a radial ball bearing. The advantages of this spindle structure: the machining and assembly of the spindle is simple, and the cost is low.

The second kind: main shaft structure with adjustable radial clearance of bearing

The front bearing of the main shaft adopts a double-row cylindrical roller bearing with P4 grade conical hole and a double-row radial ball bearing with P4 grade. The main shaft uses double-row cylindrical roller bearings with tapered bores to bear radial cutting forces, and double-row radial thrust ball bearings to bear axial cutting forces and partial radial cutting forces. The rear bearing of the main shaft generally adopts a double-row cylindrical roller bearing with P5 conical bore.

The inner ring and the matching shaft diameter of the double-row cylindrical roller bearing with tapered bore are 1:12 tapered. Locking the bearing with a round nut causes a displacement in the axial direction and expands the inner ring of the bearing, thereby reducing or eliminating The purpose of bearing radial clearance.

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