Internal grinding machines are primarily used for grinding the internal surfaces and end faces of cylindrical, conical, or other shaped surfaces. The internal grinding wheel is typically mounted on one end of a grinding wheel extension shaft, the other end of which is connected to the grinding head spindle. Some grinding machines also mount the internal grinding wheel directly on the spindle of the internal grinding tool. Grinding wheels can be fastened using either threaded fastening or adhesive fastening.
Screw fastening is the most common way to install the internal grinding wheel.
The following points should be noted when installing the grinding wheel:
1. The clearance between the inner hole of the grinding wheel and the extension shaft should be appropriate, not exceeding 0.2mm. If the clearance is too large, place paper between the inner hole of the grinding wheel and the extension shaft to prevent vibration caused by eccentric installation of the grinding wheel.
2. Both ends of the grinding wheel must be padded with soft padding, such as yellow paper, with a thickness of 0.2-0.3mm.
3. The end surface of the extension shaft of the pressure-bearing grinding wheel must be flat, and the contact surface must not be too small, otherwise the grinding wheel cannot be securely fastened.
4. The pressure-bearing end of the fastening screw must be perpendicular to the screw to ensure uniform force on the grinding wheel.
5. The screw thread direction of the fastening screw should be opposite to the direction of rotation of the grinding wheel to ensure that the grinding wheel does not loosen under the action of grinding forces.
6. Adhesive fastening is commonly used to fasten small grinding wheels with a diameter of less than 15mm.
A commonly used adhesive is a paste-like mixture of phosphoric acid solution (H3PQ4) and copper oxide (CuO) powder. During bonding, there should be a 0.2-0.3mm gap between the extension shaft and the inner bore of the internal grinding wheel. To enhance the bond strength of the grinding wheel, the outer diameter of the extension shaft can be rolled into a reticulated pattern. The adhesive should fill the gap between the grinding wheel and the extension shaft. Allow to dry naturally or in a dryer, then cool for about 5 minutes.
When using adhesive to fasten the internal grinding wheel, pay attention to the following points:
To prepare the mixture, place copper oxide powder in a porcelain container and gradually add the phosphoric acid solution while stirring continuously. Ensure the mixture is evenly distributed and maintains the appropriate concentration.
The adhesive must completely fill the gap between the grinding wheel hole and the extension shaft.
After solidification, use an electric furnace to dry the mixture. However, the drying time should be short, as this will cause the copper phosphate to rapidly expand during the solidification process, potentially cracking the grinding wheel. Visually inspect the color of the adhesive. Stop heating when it appears dark green.
There are many adhesive formulations. For example, some factories use sulfur as a bonding agent. The method is:
First, convert the sulfur into a liquid. Then apply the liquid between the extension shaft and the inner hole of the grinding wheel. Let it cool for about 5 minutes before use.
When attaching the extension shaft to the grinding wheel, when removing and attaching the extension shaft from the spindle, be sure to understand the direction of rotation of the extension shaft. When the internal grinding wheel rotates counterclockwise, the extension shaft thread should be right-handed.
When installing the internal grinding wheel on a CNC grinder, pay attention to the different handling conditions. Carefully and carefully install the grinding wheel to ensure that errors are avoided during grinding.
