High precision cylindrical grinding machine is realized by using the characteristic that a large number of micro edges with equal height can be trimmed on the working surface of grinding wheel. In addition, due to the existence of a large number of contour abrasive micro edges, a large number of extremely fine cutting marks can be left on the machined surface under the premise of appropriate grinding parameters, thus obtaining very low surface roughness. Due to the obvious friction, sliding extrusion, polishing and calendering, the surface roughness can be further reduced.
High precision cylindrical grinder of maintenance
1) Inspection and scraping of bed guide rail
After maintenance, the V-shaped guide rail of lathe bed shall meet the following accuracy requirements: out of straightness in vertical plane ≤ 0.01mm/m; non straightness in horizontal plane ≤ 0.01mm/m; non perpendicularity of slide saddle guide rail ≤ 0.02mm/250m; contact point shall be 12-14 points / 25mm × 25mm.
After maintenance, the plane guide rail of the bed should meet the following accuracy requirements: the unevenness of V-shaped guide rail is ≤ 0.02mm/m; the non straightness in the vertical plane is ≤ 0.01mm/m; the contact point is required to be 12-14 points / 25mm × 25mm.
2) Inspection and scraping of slide saddle guide rail
After maintenance, the V-shaped guide rail of the sliding saddle shall meet the following accuracy requirements: the non straightness in the vertical plane shall be ≤ 0.01mm in the whole length; the contact point shall be 10-12 points / 25 mm × 25 mm.
After maintenance, the plane guide rail of sliding saddle shall meet the following accuracy requirements: the unevenness of V-shaped guide rail shall be ≤ 0.02mm/m; the contact point shall be 10-12 points / 25mm × 25mm.
3) Clearance adjustment between grinding wheel spindle and bearing bush
Color the Journal of the grinding wheel spindle, grind it with the bearing bush, scrape the surface of the bearing bush with a scraper to make the contact point reach 12-14 points / 25 mm × 25 mm, and then install and adjust the clearance between the grinding wheel spindle and the bearing bush to 0.0025-0.005mm, so as to avoid the edge circle of the workpiece during grinding.
4) Balance between grinding wheel spindle motor and grinding wheel
The vibration of grinding wheel spindle motor has great influence on grinding surface roughness, so it is necessary to balance the grinding wheel spindle motor. The grinding wheel needs to be balanced twice: first, rough balancing is carried out after dressing the grinding wheel with diamond pen; then, the grinding wheel is finely trimmed with oilstone or finish turning dressing wheel, and then fine balancing is conducted again.
Dressing of grinding wheel for high precision cylindrical grinder
In general, the surface roughness of Ra0.4 ~ 0.8 μ M can only be obtained by grinding wheel with diamond pen. In order to meet the roughness requirement of ra0.02 ～ 0.04 μ m, the grinding wheel must be finished twice. One of the following two methods can be used for trimming.
1) Use diamond pen to finish, and then use oilstone to fine repair
The grain size of grinding wheel is generally 46 ා - 80 ා. First of all, a sharp single grain diamond pen is used to finish the grinding wheel with small and uniform feed rate, so as to trim more equal height micro edges on the grinding wheel grains. During finishing, the installation of the wheel dresser should be correct and reasonable (see Fig. 2), the feed rate should be controlled at 5 μ m each time, and the lowest longitudinal feed speed is recommended. In the process of finishing, attention should be paid to the change of the sound emitted by the trimming. If the sound is uniform, it indicates that the trimming condition is normal; if the sound is high or low, or gradually high and low, or even abnormal beep, it is necessary to immediately check whether the workbench crawls, whether the cooling is sufficient, whether the diamond pen is sharp, etc., and then make appropriate adjustment. After finishing with diamond pen, the grinding wheel can be finely trimmed with oilstone (or sand bar) to obtain more equal height micro edges on the grinding wheel grains. The whetstone needs to be ground on a surface grinder. In fine repair, the oilstone must be parallel to the surface of the grinding wheel circumference. The stone should be slightly contacted with the grinding wheel and moved longitudinally 2-3 times slowly.
2) Finish with diamond pen and then finish with grinding wheel after finishing turning
After finishing with diamond pen, taper adjustment is carried out with the mandrel whose grinding length is basically the same as that of the workpiece, and then the grinding wheel after finishing turning is used for fine trimming.
Gc80-120 × J-K grinding wheel with diameter of about 100 mm can be used for fine dressing. When turning the grinding wheel, the grinding wheel is installed on the chuck, and the chuck is clamped on an automatic centering mandrel, and then it is jacked on the two centers of the precision lathe for rough and fine turning of the outer circle, so that the outer circle of the grinding wheel does not deviate. Then, the grinding wheel after finishing turning is put on the two centers of the grinder to fine repair the grinding wheel.
In fine repair, the head frame drives the grinding wheel for dressing to rotate. Select low speed (about 80-100r / min) and small feed rate (about 2 μ m for reciprocating once). The reciprocating speed of worktable should be lower than 0.3m/min. It needs to be repaired repeatedly. The rotation direction of dressing grinding wheel and dressing grinding wheel should be the same, that is, the linear velocity direction of contact point is opposite. The coolant should be sufficient to wash away the floating sand and prevent the floating sand remaining on the grinding wheel from roughening the workpiece surface during grinding.
After the grinding wheel has been finely and finely trimmed, fingers can be used to gently approach the working surface of the grinding wheel along the rotation direction of the grinding wheel and make longitudinal movement. If the hand feels flat and smooth, such as touching the mirror surface, it means that the grinding wheel is well dressed; if it feels that there are abrasive particles on the hand, the floating sand on the surface of the grinding wheel can be gently brushed off with a paint brush with 2 / 3 bristles removed.
On 2018-08-08 11:45:46
