CNC roll grinder is an important supporting equipment for sheet metal rolling production. Its grinding accuracy and grinding efficiency directly affect the rolling quality and production efficiency of the sheet metal. The grinding mechanism has the characteristics of a general large-scale cylindrical grinder, but it is much more complicated than the movement of the cylindrical grinder. In addition to the relative rotation of the grinding wheel and the workpiece, the grinding wheel and the workpiece are required to perform relative longitudinal movement. In order to meet the technical requirements for shape control, the roll surface busbars need to be processed into various special high-order curves (such as CVC curves) according to different process requirements. This requires a certain radial relative displacement when the grinding wheel and workpiece of the CNC roll grinder make relative longitudinal movement. Therefore, the requirements for the transmission mechanism of the CNC roll grinder are very high, and the working precision of the machine tool is also high. At the same time, good grinding process parameters, grinding wheels and coolant are also important guarantees for the grinding accuracy and surface quality of the rolls.
(1) Improve rail accuracy
According to the accuracy requirements of the V-shaped guide rail of the bed, the planar guide rail of the bed, the V-shaped guide rail of the carriage base, and the planar guide rail of the carriage base, scrape the guide rail to improve its contact accuracy.
(2) By adjusting the preload and axial clearance of the ball screw, the transmission accuracy of the screw is improved. For CNC grinders, ball screws are generally used for transmission. Therefore, the transmission accuracy of the ball screw greatly affects the machining accuracy. Taking the double nut adjustment method as an example, the mechanical adjustment can adjust the gap between the single nut installed on the screw, and the axial gap is generally adjusted to about 0.005mm. After adjusting the nut clearance, start to assemble the washer. The optional gauge block is inserted between the two nuts, and then the torque is measured. If the torque is within the range required by the drawing, the grinding pad is equipped according to the size of the gauge block; if the torque is not within the range required by the drawing, the gauge block is replaced again, and then measured Torque until it meets the requirements. In addition, the backlash compensation parameter in the numerical control system parameters can be used to compensate the screw clearance, thereby improving the transmission accuracy of the ball screw.
(3) Improve the accuracy of the spindle bearing of the grinding wheel
For the dynamic pressure bearing, the bearing pad is scraped to make the contact point reach 12 ~ 14 points / 25mm × 25mm, so as to ensure that the gap between the grinding wheel main shaft and the bearing pad is adjusted to 0.0025 ~ 0.005mm. For static pressure bearings, check whether the pressure in the front and rear bearing oil chambers is normal, and ensure that the clearance reaches 0.0025 ~ 0.005mm. Measured with a dial indicator, the radial runout of the grinding wheel spindle is 0.001 ~ 0.002mm.
(4) Through the balance of the grinding wheel, the processing accuracy is improved. The static balance is improved: After the grinding wheel is installed with the flange, the grinding wheel is installed on the grinding wheel spindle. After the diamond pen is trimmed, the grinding wheel is removed and placed on the balance frame for static balancing. The method is to adjust the three adjustment blocks in the circumferential direction of the flange, so that the grinding wheel can be stabilized on the balance frame at the four 90 ° positions of the circumference. Through a good static balance, reduce the impact of grinding wheel imbalance on machining accuracy. Conditional balancing can also be carried out: After the grinding wheel is installed on the grinding wheel spindle, a dynamic balancing device is installed on the flange to make the center of gravity of the grinding wheel offset ≤0.2μm.
(5) Choose lubricating oil of guide rail reasonably, improve the lubrication of guide rail, and avoid the phenomenon of crawling.
(6) Through the use of live centers, reduce the calorific value and improve the processing accuracy.
Method For Improving Grinding Process Of CNC Roll Grinder
