Improvement of grinding process of CNC roll grinding machine
CNC roll grinding machine is an important supporting equipment for plate rolling production, and its grinding accuracy and grinding efficiency directly affect the quality of plate rolling and production efficiency. The grinding mechanism has the characteristics of a large cylindrical grinding machine, but is much more complex than the motion of a cylindrical grinding machine, which requires relative longitudinal motion of the grinding wheel and the workpiece in addition to the relative rotary motion of the grinding wheel and the workpiece. In order to meet the process requirements for plate shape control, the roll surface bus needs to be processed into various special high-square curves (such as CVC curve) as required by different process requirements. This requires the grinding wheel of CNC roll grinding machine, the workpiece for the relative longitudinal movement of the two for a certain radial relative displacement. Therefore, the transmission mechanism of CNC roll grinding machine is very demanding, and the working accuracy of the machine tool is also high. At the same time, good grinding process parameters as well as grinding wheels and coolant are also an important guarantee of roll grinding accuracy and surface quality.
(1) Improvement of guideway precision
According to the accuracy requirements of the bed V-guide, bed plane guide, drag plate seat V-guide and drag plate seat plane guide, scraping and grinding of the guide is carried out to improve its contact accuracy.
(2) Improve the transmission accuracy of the screw by adjusting the preload force and axial clearance of the ball screw For CNC grinding machines, ball screws are commonly used for transmission. Therefore, the transmission accuracy of the ball screw has a great impact on the machining accuracy. Taking the double nut adjustment method as an example, the mechanical adjustment aspect can adjust the clearance of the individual nut mounted to the screw, and the axial clearance is generally adjusted to about 0.005 mm. After the nut clearance is adjusted, the shim is started. If the torque is within the requirement of the drawing, the shim will be matched according to the size of the block; if the torque is not within the requirement of the drawing, the block will be replaced and the torque will be measured again until it meets the requirement. In addition, the backlash compensation parameter inside the CNC system parameters can be used to compensate for the screw clearance, so as to improve the transmission accuracy of the ball screw.
(3) Improve the accuracy of the grinding wheel spindle bearing
For the dynamic pressure bearing, scrape the shaft tile to make the contact point reach 12~14 points/25mm×25mm, so as to ensure that the clearance between the grinding wheel spindle and the shaft tile is adjusted to 0.0025~0.005 mm. and for the static pressure bearing, check whether the front and rear bearing oil cavity pressure is normal to ensure that the clearance reaches 0.0025~0.005 mm. measure with a micrometer, the grinding wheel spindle's Radial runout is 0.001~0.002mm.
(4) Balance the grinding wheel to improve the machining accuracy static balance: After the grinding wheel piece is installed on the flange, the grinding wheel is installed on the grinding wheel spindle, and after diamond pen dressing, the grinding wheel is taken off and put on the balance frame for static balance. The method is to adjust the three adjustment blocks on the circumference of the flange, so that the grinding wheel can be stopped in the four 90° positions of the circumference on the balancing frame. Through good static balance, reduce the impact of grinding wheel unbalance on processing accuracy. Dynamic balancing can also be carried out if there are conditions: after the grinding wheel is installed to the grinding wheel spindle, a dynamic balancing device is installed on the flange so that the offset of the center of gravity of the grinding wheel is ≤ 0.2μm.
(5) Reasonable choice of guide lubricant, improve the lubrication of the guide, and avoid crawling phenomenon.
(6) Reduce heat generation and improve machining accuracy by using live center.