Centerless grinding machines are widely used in precision machining fields as grinding equipment, mainly used for high-precision external cylindrical grinding of workpieces such as shafts and bars. Their most distinctive feature is that they do not require the use of centers or chucks to fix the workpiece, but rather complete the grinding process through the coordinated action of the abrasive wheel, guide wheel, and support plate. In this process, the adjustment of the guide wheel is particularly critical, as it not only affects the rotational speed and feed of the workpiece but also directly relates to the final processing accuracy and surface quality. This article will introduce in detail the adjustment methods and precautions of the guide wheel in centerless grinding machines.



One, The function of the guide wheel



The guide wheel mainly plays the role of supporting the workpiece and controlling its rotation and feed direction in the centerless grinder. Compared with the abrasive wheel, the guide wheel has a lower hardness and is often covered with rubber or resin layers on the surface to increase friction and prevent surface damage to the workpiece. At the same time, the guide wheel is usually tilted at an angle (usually 2°~6°) to produce axial feed of the workpiece, thus achieving continuous grinding.



Two, The adjustment steps of the guide wheel



1. Confirm the angle of the guide wheel

The angle of the guide wheel determines the axial feed force of the workpiece. Too small an angle may lead to insufficient feed and affect processing efficiency; too large an angle may cause the workpiece to jam or burn. Generally, the tilt angle of the guide wheel should be adjusted according to the material, diameter, and grinding requirements of the workpiece, usually set at about 3°.



2. Adjust the relative position of the guide wheel and the abrasive wheel

The guide wheel and the abrasive wheel should be kept parallel, and the distance between them should be slightly larger than the maximum diameter of the workpiece. Too small an间隙 will lead to over-grinding, while too large an gap will make the workpiece unable to be effectively supported, affecting stability.



3. Adjust the height of the guide wheel

The height of the guide wheel should be slightly higher than the centerline of the abrasive wheel, usually 1/3 to 1/2 of the workpiece radius higher than the centerline of the workpiece. This ensures that the workpiece rotates stably during the grinding process and maintains a good contact pressure.



4. Adjust the speed of the guide wheel

The speed of the guide wheel directly affects the rotational speed and surface quality of the workpiece. To prevent burnishing and improve smoothness, the speed of the guide wheel is usually slower than that of the abrasive wheel, generally 1/5 to 1/8 of the abrasive wheel speed. It can be adjusted by a variable frequency drive or a mechanical transmission device.



5. Adjust the air or hydraulic pressure of the guide wheel

On the centerless grinder driven by hydraulic or pneumatic pressure, the pressure of the guide wheel should be appropriately adjusted according to the material of the workpiece and the processing requirements. Excessive pressure can cause deformation or surface damage to the workpiece, while insufficient pressure will affect the grinding effect.



Three, Matters to be noted when adjusting the guide wheel



- Ensure that the equipment is de-energized before adjustment to prevent accidents caused by misoperation.

- After each adjustment, a trial grinding should be carried out to observe the workpiece size, surface quality, and feed status, and make fine adjustments if necessary.

- Regularly check the wear condition of the guide wheel and replace or repair the surface of the guide wheel in time to avoid affecting processing accuracy.

- Precision measuring tools such as micrometers, levels, and angle gauges should be used during the adjustment process to ensure adjustment accuracy.



Four, Conclusion



The guide wheel is an indispensable and important part of the centerless grinder, and its proper adjustment is of great significance for ensuring processing accuracy, improving production efficiency, and extending the service life of the equipment. Mastering the adjustment method of the guide wheel requires not only theoretical knowledge but also the accumulation of practical experience. Only through continuous operation and summary can the high-efficiency and precise processing of the centerless grinder be truly realized.