What Is a Universal Grinder?
A universal grinder is a machine tool belonging to the cylindrical grinder family that allows a single machine to perform a wide range of rotary grinding operations with a high degree of versatility and flexibility. Therefore, as a unique feature of a universal grinder, the grinding wheel head and the headstock of the workpiece can be rotated freely during external grinding, and the angle can be changed at will, providing a wide working range.
In addition to external grinding, the machine can also be used for internal grinding, taper grinding, and end-face grinding.
Uses of Universal Grinders
Universal grinders are usually used to grind the external and internal surfaces of workpieces using a rotating grinding wheel. However, since universal grinders are characterized by their versatility among cylindrical grinders, they can also be used for workpieces that are tapered in shape, even though they are usually cylindrical in shape.
Compared to other centerless grinders, cylindrical grinders are often used when high accuracy is required, especially for the roundness of workpieces and processing dimensions for surface finishing.
Principle of Universal Grinders
Universal grinders are a type of cylindrical grinder, which explains why cylindrical grinders are capable of high-precision cutting.
Unlike centerless grinders, cylindrical grinders fix both ends of the workpiece with a spindle head or centerstock. Since rotary grinding is performed while the workpiece is firmly fixed (chucked), the grinding accuracy is higher than that of the centerless grinder, which has no center and is easily affected by the external shape and roundness of the workpiece.
Another reason for the high precision of grinding is the use of a grinding wheel.
The abrasive grain corresponds to the blade being sharpened. The worn abrasive grains fall off the rotating wheel, making room for new grains on the next surface. Therefore, the grinding wheel does not need to be reground like an end mill (drill). Another feature is that there is no need for regrinding, and high machining accuracy can be maintained.
Diamond particles and CBN grains with high hardness are generally used as abrasive materials. However, it is important to use different abrasive materials for different applications, as they are suited to different workpieces to be ground.
In addition, some universal grinders feature a double-swivel wheel head for greater flexibility in the grinding position. As for the dedicated equipment for internal grinding, the upward flip-up type is common, but there is also a rear-mounted type of wheel head that rotates the wheel head 180 degrees.
In order to improve the versatility of the grinding method, the spindle head must be switchable between rotating and fixed, and the rotational speed must be adjustable.