It is necessary to leave enough machining allowance but not too much machining allowance to ensure the normal processing of the finishing.

The requirements for finishing cars are high and should be carried out by skilled workers on more sophisticated lathes. If the center hole of the rear axle of the roughing car is subject to wear, the center hole must be re-corrected to obtain an accurate machining positioning reference before the finishing car can be performed.

When finishing the car, care must be taken to ensure the size of the two bearing gears, which is what we call the shoulder, because its accuracy requirements are more stringent, and the other shafts are mostly based on it.

The requirements for finishing cars are high and should be carried out by skilled workers on more sophisticated lathes. If the center hole of the rear axle of the roughing car is subject to wear, the center hole must be re-corrected to obtain an accurate machining positioning reference before the finishing car can be performed.

The dead top mounting workpiece is relatively stable, but the wear is large. The active tip is less rigid, but avoids wear between the workpiece and the tip. Therefore, the active tip is widely used in high-speed cutting.

The finishing method of the finishing car is roughly the same as that of the roughing. When finishing the car, except for the steps that need to be ground to leave the grinding allowance (0.3~0.5 mm), the diameter and length of the other shafts are all turned to the dimensions specified in the drawings. The chamfering of the end face and the overrunning groove of the grinding wheel are also driven out at the same time.

For small motors, in order to prevent the bending deformation of the shaft during press-fitting, the iron core is pressed after the roughing of the car, and then the bearing position of the car, the shaft extension and the outer circumference of the core are finished. Or firstly, the armature gear, the commutator gear, the shaft extension, the fan gear, etc. are fine, the bearing gear is enlarged by 0.3~0.5 mm according to the drawing size, and the rotor is press-fitted, then the finished car bearing gear, the armature outer circle, The outer circumference of the commutator and other parts to ensure the coaxiality of the rotor parts.

When finishing the car, care must be taken to ensure the size of the two bearing gears, which is the shoulder we say, because its accuracy requirements are more stringent, and the other shafts are mostly used as a reference.

The direction to improve the productivity of turning machining is to improve the manufacturing precision of the blank to reduce the machining allowance; to increase the turning amount and reduce the number of passes to shorten the cutting time and auxiliary time. The advanced technology used includes high-speed cutting, powerful cutting, multi-blade multi-blade machining, and contour turning.

To improve the machining accuracy of turning, the factors affecting the machining accuracy should be analyzed according to the specific processing conditions, and corresponding measures should be taken. The clamping of the workpiece and the tool should be accurate and reliable: the rigidity of the process system should be good; the cutting edge of the tool should be carefully ground; if the cutting depth and the amount of cutting are small, the cutting force is also small, so the elastic deformation of the process system is also small, and the quality of the machined surface can be improve.

The position of the bearing at both ends of the motor shaft and the shaft extension require a high surface roughness. Although the use of fine cars can meet the requirements, but the productivity is low and the cost is high. It is economical to use a semi-finished car to grind the outer circle.

When grinding, the workpiece is placed between the two dead tops and rotated by the chicken core chuck and the dial. The purpose of using a dead top is to reduce the gap between the tip and the shaft and eliminate vibration to achieve the required machining accuracy.

When grinding the outer circle, the longitudinal feed (longitudinal grinding method) is usually used, the grinding wheel is used as the main cutting motion, and the workpiece is rotated and linearly reciprocated with the table (longitudinal feed). The grinding allowance is ground under multiple longitudinal feeds. At the end of each reciprocating stroke, the grinding wheel is cut transversely (radially). The longitudinal grinding method is characterized by high precision. For small motor shafts, lateral feed (cross-grinding) is sometimes used because the machining position is not long. The grinding wheel is only used for lateral feeding. The width of the grinding wheel is slightly larger than the length of the ground part (usually about 5 to 10 mm larger). In rough grinding, the infeed is 0.025~0.02 mm/piece per revolution. When grinding, the infeed is 0.001~0.012 mm/piece per revolution. The cross-grinding method is characterized by high work efficiency, but the deviation of the cylindricity of the outer circle is large, and the shape of the grinding wheel must be often corrected with a diamond knife.

Reprinted from the network