A centerless grinding machine is a type of grinding machine that does not require grinding the axial center of the workpiece.
A centerless grinding machine consists of three main components: the grinding wheel, the adjusting wheel, and the workpiece holder.
The grinding wheel is responsible for performing the grinding operation.
The adjusting wheel controls the rotation of the workpiece and determines the feed rate.
The workpiece holder supports the workpiece during the grinding process.
There are various ways to combine these three components to achieve the desired outcome, with the exception of stopping the grinding process, which follows the same principle.
Introduction
A centerless grinding machine with reduced lateral dimensions is ideal for use in small installation spaces and can satisfy the simplification and space-saving needs of diverse production lines.
By placing the grinding wheel finishing unit obliquely above the grinding wheel in a downward position, it eliminates the need for maintaining extra space on the side of the grinding wheel for the finishing unit. This extra space is typically related to the lateral dimensions of conventional centerless grinders.
Therefore, the lateral dimension of this centerless grinding machine can be significantly reduced. The machine’s ability to be mounted in small installation spaces helps fulfill the simplification and space-saving requirements of various production lines.
Principle
A centerless cylindrical grinding machine uses a centerless grinding method to grind a rotating surface of a workpiece. The workpiece is not centered and supported but placed between the grinding wheel and the guide wheel, which are supported by the pallet and guide wheel.
The grinding wheel is usually installed at the end of the main shaft, and a grinding wheel with a width of more than 250 mm is installed in the middle of the main shaft. The maximum width of the grinding wheel is 900 mm.
During operation, the grinding wheel rotates at high speed for grinding, and the guide wheel rotates in the same direction at a slower speed to drive the workpiece to rotate for circumferential feeding. The axial feed is realized by adjusting the slight inclination angle of the guide wheel axis, and it is suitable for grinding elongated cylindrical workpieces, short shafts without center holes, and sleeve-type workpieces.
Radial feed is achieved by the movement of the guide wheel frame or the grinding wheel frame when cutting into the grinding. This method is suitable for grinding workpieces with shoulders or bosses, as well as cones, spheres, or other curved workpieces.
Centerless grinding machines are highly productive and can be easily automated with various loading and unloading devices. They are mostly used for mass production and can be operated by less skilled workers.
Typically, centerless grinding machines have a grinding accuracy of 2 microns and a dimensional accuracy of 4 microns. High-precision centerless grinding machines are available with accuracy levels of 0.5 microns and 2 microns.
There are also centerless internal grinding machines and centerless thread grinding machines available.
Centerless grinders are automatically trimmed and compensated. The guide roller feed guide is a double V-type needle roller guide wheel, which is fed by a servo motor and can compensate with the dressing of the grinding wheel.
Additionally, the machine is equipped with an automatic loading and unloading mechanism for automatic cycle grinding.
Processing methods
Centerless cylindrical grinding machines employ three primary grinding methods, namely:
- Pass-through grinding
- Plunge and cut-through grinding
- Through centerless grinding
The direction of grinding is in line with the axis of the grinding wheel for all these methods. The axial inclination of the guide wheel can be adjusted slightly to adjust the guide wheel’s axis inclination. These methods are suitable for elongated cylindrical workpieces, as well as short shafts and nested workpieces without center holes.
Plunge centerless grinding involves axial positioning fulcrums on the pallet. The workpiece is supported at a specific position on the pallet and is ground by a grinding wheel or a guide wheel. This method is ideal for grinding workpieces with shoulders or bosses, as well as cones, spheres, or other rotating parts.
Plunge-through centerless grinding is a combination of the above two methods. Additionally, there are tangential feed grinding and end-feed grinding methods for stepped workpieces in the axial direction.
Centerless cylindrical grinding machines have high productivity, making them ideal for mass production, and are easy to automate.
