(3) X-ray crystal orientation Since the wavelength of the X-ray is close to the lattice constant of the crystal, diffraction occurs when the X-ray passes through the crystal or is reflected back from the crystal surface. A dedicated X-ray crystal orientation instrument has been developed using this principle. This crystal orientation method has high precision, but because X-rays have certain harm to the human body, it is necessary to pay attention to the protection of operators when using.

3.3 The crystal orientation of the diamond tool selects the diamond anisotropy, so not only the hardness and wear resistance of each crystal face are different, but also the wear resistance of the same crystal face in different directions. If the crystal orientation is not properly selected, the sharpening efficiency will be greatly reduced even if the crystal face is selected correctly. At the same time, since the compressive strength of the diamond crystal is 5-7 times larger than the tensile strength, the easy-grinding direction of the crystal face should be selected during the sharpening process, and the cutting edge should face the positive direction of the sharpening wheel speed (ie, take Back grinding) to ensure sharpening efficiency and reduce the degree of microscopic cleavage of the cutting edge.

3.4 Wear and damage of diamond cutters The wear mechanism of diamond cutters is complex and can be divided into macroscopic wear and microscopic wear. The former is mainly mechanical wear and the latter is mainly based on thermal chemical wear. Common diamond tool wear and tear forms are flank wear, flank wear and edge cracking. In the single crystal diamond tool sharpening process, it needs to be worn to sharpen the tool that meets the requirements, but if the unnecessary wear is generated, the sharpened front and back flank surfaces may be damaged. The edge cracking (ie, chipping) occurs when the stress on the cutting edge exceeds the local bearing capacity of the diamond tool, and is generally caused by microscopic cleavage damage of the diamond crystal along the (111) crystal plane. In ultra-precision machining, the cutting edge of the diamond cutter has a relatively small radius, which is itself a hard and brittle material. At the same time, due to its anisotropy and the (111) surface is prone to cleavage, along with the vibration and the grinding wheel to the cutting edge The impact of the mouth is often accompanied by a chipping phenomenon.

4 Grinding Test <br> <br> test was carried out on Grinder EWAG RS-12. In the test, due to the lack of effective crystal orientation means, only through the structural analysis of the scrapped tool, the direction of the crystal plane of the tool is roughly determined, and then the contact force and contact sound of the tool and the surface of the grinding wheel during the sharpening process are taken into consideration, and the speed of the grinding wheel is taken into consideration. The parameters such as the reciprocating speed of the spindle and the swing amplitude are carefully searched for the appropriate sharpening angle of the tool. When the sound of the sharpening is more boring and the machine tool has a large vibration, the tool should be immediately withdrawn to avoid damage to the grinding wheel and re-adjust the angle. After the adjustment is appropriate, the sound of the sharpening is lighter and softer, the vibration of the hand-feeling machine is small, and the continuous knife is 0.05mm, and the machine does not have vibration fluctuations.

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