Of the bearing in design of numerical control machine tool choose skill

　 of 　 of 　 of bearing of main shaft scroll (1) the resistance of attrition of bearing of scroll of type 　 　 of scroll bearing is little, can tighten beforehand, lubricant safeguard simple, can change work steadily inside limits in certain rotate speed limits and load. Roll bearing is produced by professional chemical plant, maintenance of choose and buy is convenient. But compare with sliding bearing photograph, the noise of scroll bearing is very big, scroll body number is limited, stiffness is change, fight brace up the gender is differred slightly and have very big restriction to rotate speed. Scroll bearing is bearing of ball bearing, columnar roller according to rolling the structure of body is divided. Bearing of pottery and porcelain is to show bearing rolls system is made with material of pottery and porcelain, and circle of inside and outside still uses bearing steeliness to build. Choose scroll form, because it has the following character,basically be: It is weight light, 2 it is hot coefficient of expansion small, 3 it is stretch model the amount is large. So it has centrifugal power small, kinetic friction force is small, tighten force stability beforehand, flexibility is out of shape small, the characteristic with tall stiffness. (2) of main shaft bearing reasonable decorate 　 　 　 1) before the choice of main shaft bearing and main shaft of machine tool of 　 of configuration form 　 have, hind before 2 bearing are mixed, medium, hind 3 bearing two kinds, previously person relatively much see. The configuration form of bearing of two bearing main shaft, include the type selecting of main shaft bearing, combination and decorate, main basis involves main shaft component to wait for the requirement of the respect in rotate speed, carrying capacity, stiffness and precision to place. The following and general principle should follow when deciding bearing of two bearing main shaft configures a form: ① gets used to the requirement of stiffness and carrying capacity: The choice of form of configuration of main shaft bearing should satisfy the stiffness of a requirement and carrying capacity above all. ② gets used to rotate speed requirement: The top rotate speed that the bearing place of different type, norms and accuracy class allows is different. Below same condition, of point contact those who compare line contact is tall; Columnar roller is higher than tapered roller. ③ gets used to the requirement of precision: Main shaft package stands the axial position precision that the thrust bearing of axial force configures a form to affect main shaft directly. 2) the matter that certain machine tool of 　 of 　 of component of 3 bearing main shaft designs as a result of the structure, bring about length of main shaft box longer, its main shaft the bearing span between two bearing is ambitious at optimal span, right now, the stiffness that should consider to add the bearing intermediate to raise main shaft package and fight brace up quality. 3) the stiffness of the stiffness that the application of bearing of main shaft scroll designs bearing of scroll of main shaft of ① of 　 　 　 and bearing of scroll of 　 of carrying capacity 　 basically depends on the osculatory stiffness between scroll body and raceway. The stiffness of athletic bearing and bearing type, load and tighten a circumstance to concern beforehand, and show as the accretion of load nonlinear characteristic. The lubricant 　 　 of bearing of ② main shaft lubricates to have very big effect to the life of the character of service of main shaft component and bearing. Lubricant unreasonable likelihood causes quantity of heat to increase, reduce precision of main shaft job, quicken bearing to wear away. Use at rolling the lubricant of bearing can be divided to be two kinds big, namely grease lubricant and liquid lubricant. The action of the seal unit of bearing of scroll of sealed 　 　 of bearing of scroll of ③ main shaft is in with prevent cooling fluid, cut bits, dirt, sundry etc enter bearing, make lubricant maintains without leak ground inside bearing, develop the property of bearing adequately thereby, ensure the service life of bearing. It is to the requirement of seal unit of main shaft component: The rotate speed of appropriate main shaft, get used to working environment, structure close together. The sealed cent contact of main shaft bearing and blame contact. Former can divide again for radial sealing ring sealed box felt is encircled sealed, apply to low speed main shaft commonly. Blame contact is sealed can divide for clearance type Qu Lu type is sealed, sealed box gasket type is sealed, to assure sealed action, rotate to should be less than with the bottom clearance of fixed part partly 0.

2-0.

3mm, in sealed place due answer oil to accuse, leak in case oily. 2.

　 of 　 of main shaft sliding bearing sliding bearing is fought goodly because of having brace up gender, rotate precision tall, motion is smooth wait for a characteristic, apply at machine tool of numerical control of the nicety of high speed or low speed, high accuracy. Main shaft sliding bearing presses the kind that produces oily film, can divide mix for dynamic pressure bearing static press bearing two kinds big. Differ according to fluid medium can divide move sliding bearing compatibly for liquid sliding bearing. (1) there is lube to be in greatly from clearance when main shaft relying on to rotate with certain rotate speed when bearing of dynamic pressure of 　 of 　 of bearing of liquid dynamic pressure to clearance small part flows, form pressure oily film and have main shaft surplus, make load. (2) the liquid is static pressure liquid of bearing 　 　 is static press bearing by a special system that offer oil, restrictor and bearing 3 parts are comprised. Static press bearing and photograph of dynamic pressure bearing to have a place than having as follows: Carrying capacity is high, rotate tall, oily film has precision the action of leveling error, can raise treatment precision, fight brace up the gender is good, movement is smooth, can be in already extremely the job below low speed, also can be in extremely the job below high speed, attrition is small, bearing life is long. Static pressing the drawback with main bearing is to need a special device that offer oil, bearing workmanship complex, cost is high. (3) what serve as medium with air is static press bearing to call gas static press bearing, also call gas surplus bearing or air bearing, its job principle and liquid are static press an axis identical. Because airy viscosity is smaller than the liquid much, attrition is small, power loss is small, can work below extremely high rotate speed or extremely low temperature, oscillatory, noise is particularly little, rotate precision is tall, life is long, basically do not need to safeguard, use at high speed, in exceeding component of main shaft of machine tool of numerical control of high speed, high accuracy. (4) magnetic force bearing is a kind of new-style high-powered bearing, have the special performance that all sorts of traditional bearing cannot compare. Magnetic force bearing does not grant journal surface contact, nonexistent machinery chafes and wear away, do not need lubricate and sealed, temperature rise is small, heat is out of shape small, rotate speed is high, life is long, specific power consumption is low; System of control of basic electromagnetism feedback assures magnetic force bearing the whirl of main shaft precision, stiffness and obstruction are adjustable accuse, can eliminate balance of rotor quality ministry, circumgyrate character can be obtained by sensor and control system, facilitating condition monitoring and diagnose. Magnetic force bearing basically is used in the main shaft component of machining center. CNC Milling CNC Machining