- The principle of first roughing and then finishing of lathe: the machining sequence of each surface is in accordance with rough machining and semi finishing of leaves_ Finish machining_ The precision machining is carried out in order to improve the machining accuracy and reduce the surface roughness.
- The first principle of lathe datum plane: the surface used as precision datum should be processed first, because the more accurate the surface of positioning datum is, the smaller the clamping error is. Since the lathe inverted 40 outer circle is the basis of coaxiality, the surface should be machined first, and then other surfaces.
- The principle of the lathe first and then the second: the main working surface and assembly base surface of the parts should be processed first, so as to detect the possible defects on the main surface of the blank as soon as possible. The secondary surface of the lathe can be interleaved, after the main surface is machined to a certain extent and before the final finish machining.
- The principle of lathe from near to far: in general, after the workpiece is clamped, the parts near the tool rest are processed first, and the parts far away from the tool rest are processed later, so as to shorten the moving distance of the cutting tool and reduce the idle travel time. Moreover, it is beneficial to maintain the chip of the blank or semi-finished product and improve its cutting conditions. For the inner hole of lathe parts, the inner conical hole should be machined first, then the inner hole of φ 30mm, and finally the inner hole of φ 20mm.
Key technologies of processing:
The key technology of precision machining of lathe parts is the overall comprehensive design technology of lathe parts and machine tool system. Conventional machine tool design and manufacturing, each link technology has a great tolerance. Each link of ultra precision machine tool is basically in a state of technical limit or critical application, which link is slightly considered or not handled properly will lead to the overall failure. Therefore, the design needs to have a very comprehensive and profound understanding of the whole machine tool system and the technology of each part. According to the feasibility and from the overall optimization, it is necessary to carry out the related comprehensive design in great detail. High rigidity, high stability machine body structure design, manufacturing technology. In particular, lodtm machine tool, because of its large body, its own weight, load-bearing workpiece weight changes greatly, any small deformation will affect the machining accuracy. In addition to meeting the requirements of material, structure form and technology, the operability of the machine tool must be taken into account in the structural design.
Spindle technology of ultra precision lathe parts. The scheme of Aerostatic Spindle is often used in medium and small machine tools. Aerostatic Spindle has small damping and is suitable for high-speed rotary machining applications, but its bearing capacity is small. The rotary accuracy of Aerostatic Spindle can reach 0.05 μ M. The spindle of lodtm machine tool bears large size and weight of workpiece, so hydrostatic spindle should be used generally. The hydrostatic spindle has large damping, good vibration resistance and large bearing capacity, but the high-speed heating of hydrostatic spindle is large, so liquid cooling and constant temperature measures should be taken. The rotation accuracy of hydrostatic spindle can reach 0.1 μ M. In order to ensure the accuracy and stability of the spindle, both pneumatic and hydraulic sources need constant temperature, filtration and pressure precision control.
High precision air, liquid, temperature, vibration and other working environment control technology of lathe parts. Vibration isolation and horizontal attitude control of machine tool. The influence of vibration on ultra precision machining is very obvious, which is affected by far driving cars. Special measures should be taken to isolate the vibration of the machine tool. The air floating vibration isolation system of machine tool should also have the function of automatic leveling to prevent the influence of horizontal state change on machining. For the machine tool with high lodtm vibration isolation requirements, the natural frequency of the vibration isolation system should be less than 1Hz.
