High speed angular contact ball bearing manufacturers to understand the performance of CNC gold cutting machine tool high-speed spindle, to a considerable extent depends on the spindle bearing and its lubrication. Machine tool bearings China’s bearing industry is developing rapidly.
Bearing varieties from less to more, product quality and technical level from low to high, the industry scale from small to large, has formed a product category is basically complete, the production layout is more reasonable professional production system. Spindle bearings have limited tolerances. They are particularly suitable for bearing arrangements that require very high guidance accuracy and speed capability. They are particularly suitable for bearing arrangements for shafts in machine tools. Rolling bearings are favored not only for general cutting machine tool spindles but also for high-speed cutting machines due to their good stiffness, the fact that they can be manufactured with high precision, high load carrying capacity and relatively simple structure. From the point of view of high speed, rolling bearings in angular contact ball bearings, cylindrical roller bearings second, tapered roller bearings the worst.
High speed angular contact ball bearings of the ball is both public rotation and rotation, will produce centrifugal force Fc and gyroscopic moment Mg. As the spindle speed increases, the centrifugal force Fc and gyroscopic moment Mg will also increase sharply, so that the bearing produces a large contact stress, which leads to increased friction, temperature increase, precision decline and shorten the life of the bearing. Therefore, to improve the high-speed performance of such bearings, we should find ways to suppress the increase of Fc and Mg.
From high speed angular contact ball bearing Fc and Mg formula to know, reduce the ball material density, ball diameter and ball contact angle are conducive to reduce Fc and Mg, so now the high-speed spindle more use contact angle of 15 ° or 20 ° small ball diameter bearings. However, the ball diameter can not be reduced too much, basically only 70% of the standard series ball diameter, so as not to weaken the stiffness of the bearing, more critical or to seek improvements in the ball material.
Compared with GCr15 bearing steel, silicon nitride (Si3N4) ceramic density is only 41% of it, the ball made of silicon nitride to much lighter, naturally in the high-speed rotary centrifugal force and gyroscopic moment is also much smaller.
Silicon nitride ceramic modulus of elasticity and hardness is 1.5 times the bearing steel and 2.3 times, while the coefficient of thermal expansion is only 25% of the bearing steel, which can improve the stiffness and life of the bearing, but also make the bearing clearance in different temperature conditions change small, reliable work, coupled with the ceramic high temperature and does not occur with the metal sticky bite, obviously with silicon nitride ceramic production ball more suitable for high-speed rotation. Practice shows that the ceramic ball angular contact ball bearing and the corresponding steel ball bearing compared to the speed can be increased by 25% to 35%.
Foreign will be the inner and outer ring for the steel, rolling body for the ceramic bearings collectively known as hybrid bearings.
First, ceramic materials have been used to make cylindrical roller bearing rollers, the market appeared on the ceramic cylindrical hybrid bearings.
The second is the use of stainless steel instead of bearing steel bearing inner and outer ring, especially the inner ring, due to the coefficient of thermal expansion of stainless steel than bearing steel is 20% smaller, naturally in the high-speed rotation, due to thermal expansion of the inner ring caused by the increase in contact stress trend will be suppressed.