Precision cylindrical grinding machine is different from cylindrical grinding. In internal grinding, the diameter of grinding wheel is limited by the hole diameter of workpiece, which is generally small. Therefore, the grinding wheel wears quickly and needs to be repaired and replaced frequently. The grinding wheel used in internal grinding is softer than that used in precision cylindrical grinding machine because the contact area between grinding wheel and workpiece is larger. In addition, the diameter of the grinding wheel shaft is relatively small, the overhanging length is large, and the rigidity is very poor, so the grinding depth cannot be large, and the consumption rate is reduced.
The outer circle of the workpiece is usually ground on a precision cylindrical grinder or cylindrical grinder. The cylindrical grinding of precision cylindrical grinder has three ways: longitudinal grinding, transverse grinding and deep grinding.
(1) Precision cylindrical grinder longitudinal grinding method, longitudinal grinding method, grinding wheel high-speed rotation of the main movement no, the workpiece for circular feed motion, but also with the task table for longitudinal reciprocating motion, along with the workpiece axial feed FA. At the end of each single stroke or each reciprocating stroke, the grinding wheel moves horizontally periodically to complete the feed fr along the radial direction of the workpiece, so as to gradually grind all the remaining grinding allowance in the radial direction of the workpiece. After grinding to the size, stop the grinding process without cross feed until the spark disappears. Because of the less radial feed fr, less grinding force and better heat dissipation condition, the longitudinal grinding method can improve the grinding accuracy and surface quality of the workpiece, and can meet the requirements of higher machining quality, but the grinding efficiency is low. The longitudinal grinding method is suitable for grinding larger workpiece, which is a common method for single piece and small batch consumption.
(2) The transverse grinding method of precision cylindrical grinder, when grinding the outer circle with the cross grinding method, the width of the grinding wheel is larger than that of the workpiece, and the workpiece does not need to make longitudinal (axial) feed movement. The grinding wheel continuously or intermittently moves along the transverse feed at a slow speed to complete the radial feed fr of the workpiece until the grinding meets the size requirements. Its characteristics are: fully develop the cutting ability of grinding wheel, high grinding efficiency, but also suitable for form grinding. However, in the grinding process, the contact area between the grinding wheel and the workpiece is large, which makes the grinding force increase, and the workpiece is prone to deformation and burn. In addition, the shape error of grinding wheel indirectly affects the geometric shape accuracy of workpiece, the grinding accuracy is low, and the surface roughness value is large. Therefore, it is necessary to use a grinder with high power and good rigidity. At the same time, sufficient cutting fluid must be given to achieve the purpose of cooling. Using the transverse grinding method, the process should be fragmentary and rigid, and the workpiece should be short rather than long. This kind of grinding method is usually used in the fine grinding process of short stepped shaft journal.
(3) Deep grinding method of precision cylindrical grinder, deep grinding method is a relatively advanced method with high consumption rate. The grinding allowance is generally 0.1-0.35mm. With this method, the whole allowance can be ground in one pass. When grinding, the feed rate is small. Generally, the longitudinal feed rate is 1-2mm / R, which is about 15% of the "longitudinal grinding method", and the working time is about 30-75% of the longitudinal grinding method.
On 2018-08-08 11:45:46
