The motion unit is the most important part in the structure of CNC router, and it plays an important role in the precision and performance of the machine. The common form of motion mainly has the rack and pinion structure and the ballscrew structure, so we mainly describe the characteristics and advantages of these kinds of motion structure.
1. Rack and pinion transmission looks from the transmission theory about the work is equally accuracy is certainly not as ballscrew. Why computer engraving machine is a machine rack and rack machine price is than the screw confidential expensive. The reason is only one in order to get faster processing speed to improve efficiency. Because the screw of the fixed way for bearing a long part of the distance is suspended, so when the screw machine set high speed feed will produce a certain degree of impact on the finish. If the problem is solved with a sufficiently robust lead screw, the required lead screw will be higher in price and is required to be equipped with enough power to drive the motor. The rack's application just makes up for this deficiency. Because the rack is a side completely fixed to the body of a total of a small, and the rack structure for the side of a way to ensure the stability of the. Also because a set of two and two motors, the price is slightly more expensive than the screw, but the price is much better than a robust lead screw and a huge drive motor. But the accuracy is indeed than with the specifications of the screw of slightly less than, of course, computer engraving machine used in, organic glass / advertising material / Woodworking / furniture / marble processing, I believe the reach 0.05mm precision enough to meet the needs of the. This is the machine rack to create a market demand.
Helical rack and pinion transmission is more stable than vertical rack and pinion, with the same width of the helical racks, helical pinion and rack is more efficiency than vertical rack and pinion, but practical application in the vertical rack structure is much more than a helical rack. This is because:
① Vertical rack transmission is relatively easy in machining, installation and debugging.
② The same size, the material of the vertical rack and pinion processing costs as long as the 1/2-1/3 costs of the helical rack and pinion processing.
③ Helical rack and pinion processing or installation is not in place, then the effect is worse than the vertical rack and pinion.
Therefore, in reality, in addition to the requirements of the higher, or the heavy load structure is in the use of helical rack and pinion transmission, the general is in the use of vertical rack and pinion transmission. And some unscrupulous businessmen create a selling point of the Helical rack and pinion, in fact, they use inferior Helical rack and pinion instead. This will only do the opposite. Now STYLECNC recommended not to blind Helical rack and pinion.
2. Ballscrew transmission.
① Ballscrew transmission device for machine tools and precision machinery, the most commonly used, its main function is to convert rotary motion into linear motion, or the torque convert axial force it repeatedly, has both high precision and reversible and efficient characteristics.
② The Ballscrew is composed of a screw, a nut and a ball. Its function is to convert the rotary motion into linear motion, which is the further extension and development of Ballscrews, the important significance of this development is the bearing from the rolling action into a sliding action. The Ballscrew is widely used in all kinds of industrial equipment and precision instruments because of the very small frictional resistance.
③ Characteristics of Ballscrew:
a. Compared with the sliding / trapezoidal screw, the driving torque is 1/3.
Because there are a lot of balls in the Ballscrew shaft and screw nut to do the rolling movement, so it can get a higher efficiency. Compared with the past sliding lead screw drive torque to 1/3 below, that is, to achieve the same movement of the power required for the use of the power to use the rolling screw pair 1/3. Helpful in saving electricity.
b. Micro feed possible.
Ballscrew pair is the use of ball movement, so the start torque is very small, there will not be a sliding movement of the crawling phenomenon, can ensure the realization of accurate micro feed.
c. High accuracy assurance.
Ballscrew is produced by the world's highest level of machinery and equipment coherence from Japan, especially in grinding, assembly, check the process of the factory environment, on the temperature and humidity were strictly controlled, because of perfect quality management system make the accuracy can be fully guaranteed.
d. High speed feed possible.
Because of high efficiency and low heat, the Ballscrew can be realized in high speed.
e. No backlash, high rigidity.
Ballscrew can be added to the pressure, due to pressure the axial clearance can reach negative values, and get a higher rigidity (within the Ballscrew through to the ball and the pre pressure, when in actual use mechanical devices, due to the repulsive force ball can enhance the rigidity of the screw nut).
3. ladder type screw drive lead screw is composed of screw, nut and ball, it is the rotary motion into a linear motion, or the linear motion into rotary motion of the ideal transmission components. The lead screw is widely used in all kinds of industrial equipment and precision instruments because of its small frictional resistance. Earlier the equipment used in the trapezoidal screw, because it has good load capacity and stability, but with the progress of the processing technology, Ballscrew bearing force and stability gradually replaced trapezoidal screw, while at the same time having trapezoidal screw does not have the higher accuracy and fire back ability is poor. So now the general industrial equipment on the Ballscrew has basically replaced the trapezoidal screw.