Grinding wheel is an indispensable part of grinding equipment. When grinding the inner circle, the internal grinding wheel plays a vital role. However, in the process of grinding the internal grinding wheel, the internal grinding method is different, and the choice of internal grinding wheel is also different. So, how to choose the internal grinding wheel?
1. Selection of grinding wheel diameter
The selection of grinding wheel diameter is a relatively complex issue in internal grinding. On the one hand, in order to obtain a more ideal grinding speed, a grinding wheel close to the aperture size should be used; but on the other hand, when the grinding wheel diameter increases, the contact arc between the grinding wheel and the workpiece increases accordingly, which increases the grinding heat and makes cooling and chip removal more difficult. In order to obtain a good grinding effect, the grinding wheel diameter and the aperture should have an appropriate ratio, which is usually between 0.5 and 0.9.
When the workpiece aperture is small, the main problem is the low peripheral speed of the grinding wheel, and a larger ratio can be taken at this time; when the workpiece aperture is greater than 100mm, the peripheral speed of the grinding wheel is higher, and heat generation and chip removal become the main problems, so a smaller ratio should be taken. When the inner diameter of the workpiece is greater than 100mm, it should be noted that the peripheral speed of the grinding wheel should not exceed the maximum working speed of the grinding wheel.
2. Selection of grinding wheel width
The use of a wider grinding wheel is conducive to improving the surface quality and production efficiency of the workpiece, and can reduce the wear of the grinding wheel. The grinding wheel should not be too wide, otherwise the grinding force will increase, causing the bending deformation of the grinding wheel connecting the long axis.
3. Selection of grinding wheel hardness
The contact arc of internal grinding is large, and the heat dissipation condition of the workpiece is poor. Only by giving full play to the "self-sharpening" of the grinding wheel can the grinding force and grinding heat be reduced. Therefore, a softer grinding wheel should be selected. Usually, the hardness of the grinding wheel used for internal grinding is 1-2 grades softer than that of the grinding wheel used for external grinding. When grinding a small hole with a long length, in order to avoid the taper of the workpiece, the hardness of the grinding wheel should not be too low. Generally, the hardness of the internal grinding wheel is medium soft.
4. Selection of grinding wheel grain size
In order to improve the cutting ability of abrasive grains and avoid burning the workpiece, a coarser grain size should be selected. The commonly used grinding wheel grain sizes for internal grinding are 36, 36 and 60.
5. Selection of grinding wheel structure
Internal grinding is difficult to remove chips. In order to have a larger gap to accommodate the grinding chips and avoid premature clogging of the grinding wheel, the structure of the grinding wheel used for internal grinding should be 1-2 looser than that used for external grinding.
6. Selection of grinding wheel shape
The commonly used grinding wheel shapes for internal grinding are flat and single-sided concave. In addition to grinding the inner hole, the single-sided concave grinding wheel can also grind the end face of the step hole.
When selecting an internal grinding wheel, it is necessary to select various aspects of the grinding wheel according to the grinding requirements of the inner circle, and the cost of the grinding wheel cannot be ignored. In this way, the appropriate grinding wheel can be selected to achieve the goal of high quality and low cost.
