China is a big demand for machine tools, but also the production of large countries, but only in the low-end areas are more fully meet the domestic industrial needs, high-end areas have been involved in less. With the development of the industry and the upgrading of competition, improve product technology content, with independent patents, design is the best choice for long-term development of enterprises. Therefore, the CNC vertical car, how to achieve products from low to high-end, from the primary processing to sophisticated manufacturing is the tide of corporate transformation should be thinking and efforts in the direction.
In the vertical equipment, rotary table is to reflect the overall performance of the machine to achieve the accuracy of the workpiece processing one of the core structure. We require it to run at high speed and bear the heavier workpieces at the same time, with precise operating accuracy and very high anti-overturning moment capability, while supporting the table Roller Bearings is the key to the completion of this important mission. Before the majority of domestic workstations choose thrust Roller Bearings s and radial Roller Bearings s with the use of this layout of the complex structure, more materials, especially in the placement of large box parts, the entire machine space is more bulky. Roller Bearings installation and preload adjustment is also more difficult, even more difficult to guarantee, the overall accuracy of the table is difficult to improve. Therefore, now more design began to use more compact structure of the cross roller Roller Bearings s, not only save material costs, and design simplification, higher speed limit, better operating accuracy and stability, load capacity and rigidity are stronger. This article describes how to apply crossed roller Roller Bearings s to a vertical lathe to achieve its perfect engineering performance.
One, beating accuracy
Roller Bearings beating can be divided into synchronous jitter and asynchronous beating, in which the effect of synchronous jitter on the overall beating of the worktable can be minimized by grinding the work surface, but the effect of asynchronous beating can not be eliminated in this link. Is determined by the roller outer diameter tolerance and roundness. Therefore, the better the control of the asynchronous runout of the Roller Bearings , the smaller the final radial and axial runout of the table, ie the higher the operating accuracy. In the choice of Roller Bearings brand and accuracy level, it is recommended not to focus only on Roller Bearings assembly beating, but should be in-depth understanding of the impact of Roller Bearings asynchronous beating accuracy standards.
Second, Roller Bearings with
Roller Bearings selection when the proposed inner ring and shaft, outer ring and ring gear are tight fit. The outer ring because it is rotating parts, the amount of tight should be slightly larger; the inner ring will be pressed down the cover, adjust to a certain amount of preload, so the tight amount should be slightly smaller. However, if the inner ring is considered to be a stationary part and the inner ring and the shaft are designed to be loose (there is a radial gap between the inner and the shaft), it is possible to install the inner ring, the locking inner ring or the Roller Bearings The circle is skewed, that is, eccentricity occurs. This eccentricity will cause the roller and the raceway contact area boundary stress concentration, resulting in serious scratches, pressure pit and peeling, the early end of Roller Bearings life.
Third, shape and position tolerance
The mounting surface of the shaft and the ring gear requires a flatness, verticality, roundness and degree of cylindricality consistent with the precision Roller Bearings s. Control these shape and position tolerance not only can get better assembly accuracy, but also to avoid excessive eccentricity of the Roller Bearings inner and outer ring and produce stress concentration, extend the Roller Bearings life. On the shape and position tolerance of the processing standards, it is recommended to consult the Roller Bearings supplier, matching its Roller Bearings accuracy can be.
Fourth, the axial preload
The cutting test of the lathe is very concerned with the end face and the roughness of the workpiece, and one of the keys to determining its superiority is the rigidity of the system. System rigidity includes the rigidity of the frame structure, the rigidity of the Roller Bearings , etc., where the rigidity of the Roller Bearings is often dependent on its axial preload.
In practical applications, the Roller Bearings A row of rollers is mainly subjected to overturning moments, while the C rows of rollers are primarily subjected to axial loads. When the Roller Bearings outer ring load, A row of rollers and the Roller Bearings ring has a downward trend, that is, axial clearance increases, and C row of rollers are pressed, that is, axial clearance reduced. If the Roller Bearings axial preload is insufficient, load-Roller Bearings , A row of rollers not only lost preload, and there is a clearance between the raceway, the system rigid and therefore rapid decline, then when the cutting force to produce overturning moment, the workpiece radial Deformation will be greatly increased, while the surface roughness is also very poor; if the axial preload is too large, because the C row of rollers to bear the weight of the workpiece and the Roller Bearings internal preload, and the contact between the raceway stress It is possible to exceed the allowable limit, greatly reducing the Roller Bearings life. Therefore, taking into account the impact of temperature and load, it is important to set the axial preload of the Roller Bearings reasonably.