How high roughness can CNC lathe roll?

(1) Whether the rolling pressure is selected correctly has an influence on the surface roughness, size and accuracy after rolling. Generally speaking, the surface roughness increases with the increase of rolling pressure. However, when the rolling force increases to a certain extent, the surface roughness will no longer increase. If it continues to increase, the rolling surface will become worse and even crack will appear.

(2) To improve the surface roughness of the workpiece, rolling is the best method. When the pretreatment roughness reaches Ra 1.6, the roughness can reach Ra0.2 or above as long as the interference is appropriate. However, when the roughness of pretreatment is only Ra 6.4 ~ Ra 3.2, and the machined surface has vibration and random cutter lines, then the deeper cutter lines cannot be rolled, and they can only be rolled again by increasing the interference. If the ellipticity and taper of the hole are too large, the above defects still exist after rolling, and the roughness is large. Therefore, the surface after pretreatment is better than Ra3.2, and the geometric accuracy is above one or two, thus obtaining smaller roughness and ideal accuracy.

(3) The material is soft, plastic and easy to roll. With the decrease of plasticity and the increase of hardness, the permanent deformation decreases. Generally speaking, the rolling effect of steel and copper is better than cast iron. Malleable cast iron and nodular cast iron have better rolling effect than gray cast iron. When iron castings are rolled, when the hardness of casting materials is uneven, defects (air holes, sand holes, etc. ) will be exposed immediately. Therefore, in the case of hidden surface and poor quality of castings, rolling process is not suitable.

(4) Rolling interference has great influence on surface roughness and geometric accuracy. Experiments show that the most reasonable rolling interference is 0.027 ~ 0.036 mm, and the surface roughness is the smallest. The maximum surplus is influenced by many factors, so the determination of the best surplus should be determined by trial and error according to the specific situation.

(5) The rolling speed has little effect on the surface roughness, so the production efficiency can be improved by increasing the rolling speed.

(6) The rolling times should not be too much. The effect of one-time rolling is the most remarkable, and the roughness can be reduced by 2 ~ 3 grades. The second and third times.

(7) The feed speed should be determined according to the diameter of the ball. The smaller the feed, the smaller the surface roughness. The optimum feeding speed should be determined by experiments.

(8) Rolling tools usually include balls, cylindrical rollers, tapered rollers and rollers. However, using balls as deformation members can reduce the cost of the whole rolling tool. Moreover, the ball has high precision, high hardness and small contact surface with the workpiece. The rolling pressure is small, the interference is small, and higher pressure and smaller roughness can be obtained. In addition, the ball has long service life, is not easy to wear, is cheap and easy to replace.