1 basic principle
Frequency more than 16000Hz of sound waves is called ultrasonic, ultrasonic machining is the use of tools for ultrasonic frequency vibration, through the abrasive grain impact and abrasive workpiece, so as to make the workpiece molding of a processing method. As shown in Figure 2-58, processing, tools to a certain pressure on the workpiece, the processing area into the abrasive liquid, high-frequency vibration of the end face of the tool whacking the abrasive particles on the surface of the workpiece, through the abrasive particles will be crushed by the material in the processing area. The circulating flow of the abrasive liquid takes away the particles of the material that is crushed down, and keeps the abrasive particles updated. The tool gradually penetrates deeper into the material, and the shape of the tool is reproduced on the workpiece.
Figure 2-58 Schematic diagram of the principle of ultrasonic machining
2 Process characteristics and applications
(1) Mainly applicable to the processing of a variety of non-conductive hard and brittle materials, such as ceramics, glass, quartz, gemstones, onyx, diamond and so on. For conductive carbide and hardened steel can also be processed, but the efficiency is very low.
(2) Because the relative motion between the tool and the workpiece during processing is relatively simple, so it is easy to process a variety of complex shapes of the inner surface and molding surface, etc.. The use of hollow shape tools also allows for various shapes of nesting.
(3) the machining process, the tool on the machining material of the macro force is small, the cutting heat is even smaller, will not produce deformation and surface burns, so especially suitable for processing some can not withstand a large mechanical stress of the thin-walled, narrow slit, low-stiffness parts.
(4) because the material is broken down by the direct action of the abrasive, so the hardness of the tool material can be lower than the hardness of the processed material, while the abrasive hardness should generally be higher than the processed material. Usually available medium carbon steel and a variety of molding pipe and wire for tools.
At present, in various industrial sectors, ultrasonic processing is mainly used for hard and brittle materials, hole processing, nesting, cutting, engraving, and grinding diamond wire drawing die. Figure 2-59 shows examples of ultrasonic machining applications. However, ultrasonic machining has a small area and a large wear and tear on the tool head, resulting in low productivity. General ultrasonic processing of the hole diameter range of 0.1 ~ 90mm, the depth of up to 100mm or more, the size of the processed hole error is less than ± (0.02 ~ 0.05) mm.
Figure 2-59 ultrasonic machining applications