As one of the most important processes in ultra-precision machining ultra-precision mechanical grinding is also a traditional machining method for diamond tools. It belongs to the typical methods of creative process, the characteristic is on the average accuracy of machine tools, lower depends on the precision of the machine tool, and is more dependent on take a series of effective technology in the process of process methods, measures, methods and enterprise technical know-how, can make the processed workpiece to achieve higher accuracy, has simple equipment, easy operation, obvious effect, Economic advantages.
The manufacturing process of machining diamond cutter by mechanical grinding method generally includes material selection, orientation, sawing, cutting, clamping, rough grinding, fine grinding and inspection. Rough grinding and precision process are realized by mechanical grinding method. Diamond tool is the main task of the coarse grinding to remove surplus, at this moment the main problem is how to improve the grinding efficiency, but to grinding quality also to have certain requirements, coarsely ground after the diamond surface are requested not to have big scratches, cutting tool edge cannot have collapse edge or other defects, otherwise will give lapping caused great difficulties, coarsely ground when general selection pressure for the 9 ~ 12 n; The precision grinding and machining of diamond tools is the key process to manufacture precision diamond tools. At this time, the starting point of the problem is how to improve the grinding quality and make the cutting edge more sharp. Because fine grinding is the final process to determine the grinding quality of tools, it has always been regarded as the focus of research.
At present, there have been many studies on improving the quality of fine grinding tools based on factors such as grinding speed, grinding pressure, grinding disk end jump and vibration in mechanical grinding. The conclusions are as follows:
(1) The disc end jump and machine tool vibration on grinding quality of grinding disc end jump and machine tool vibration will cause grinding disc impact on the blade, thereby destroying the flatness of the blade, especially the disc end jump effect is more direct, this is because the impact direction caused by the end jump perpendicular to the disc. There is a critical value for the influence of plate end jump and machine tool vibration on the serration of the force edge, and when the value is less than the critical value, the serration of the blade tends to zero. When the value is greater than the critical value, the blade serration increases sharply.
(2) The effect of grinding rate on grinding efficiency The higher the grinding rate, the higher the hot spot temperature, thus aggravating various mechanisms of material removal (mainly mechanical wear and thermochemical removal) and improving the grinding efficiency. Generally speaking, coarse grinding to remove the allowance for the main purpose, grinding speed in 30m/s is more appropriate. However, in fine grinding, the main purpose is to obtain a perfect edge. In order to reduce the impact of grinding powder on the edge, the grinding speed can be reduced to 20~25m/s.
(3) Influence of grinding pressure on grinding efficiency The grinding rate of diamond can also be improved by increasing grinding positive pressure P and grinding temperature rise. But the added pressure is too large, will affect the surface quality of the grinding diamond, but also aggravate the grinding disc wear, rough grinding pressure is generally 9~12N, fine grinding is about 5N.
In addition, grinding Angle, deflection Angle, grinding trajectory, grinding particle size and grinding disk surface state are also considered to be important factors affecting grinding quality. The surface of the grinding disc must be carefully treated during grinding, using very fine diamond grinding powder to find the best grinding direction.
To sum up, the grinding quality of diamond tools is very sensitive to various processing conditions, especially when grinding diamond tools with small blade wedge Angle (such as ophthalmic scalpel, fiber cutting knife and biological slicing knife). Appropriate grinding speed and grinding pressure and the use of high precision, smooth operation and small vibration of the grinding machine (such as aerostatic bearing grinding machine), in order to ensure that all kinds of processing conditions are in the ideal state, it is possible to grind out no collapse mouth, small blade serrated high quality diamond tools.