Ball screw structure
The ball screw is mainly composed of screw, nut, steel ball, fixed seat, wiper and return pipe. According to the different circulation system, it is divided into external circulation, internal circulation and end plug circulation.
The structure of the ball screw is traditionally divided into two types: inner circulation structure (represented by circular and elliptical inverters) and outer circulation structure (represented by intubation tubes).
These two structures are also the most commonly used structures. There is no essential difference in the performance of these two structures, except that the inner circulation structure has a small installation and connection size; the outer circulation structure has a large installation connection size.
There are more than 10 kinds of ball screw structures, but the more commonly used ones are: inner circulation structure; outer circulation structure; end cover structure; cover structure.There are various shapes of internal circulation structure reversers, but the commonly used shapes are round and elliptical.
Since the reverse channel of the round ball is shorter, it is not as smooth as the oval structure. The best reverser structure is an elliptical inner channel structure. Because the ball does not pass through the screw tooth tip in the reverse direction, it is similar to an outer circulation structure. Therefore, the influence of the chamfering error of the screw tooth tip on the ball reversal is eliminated. However, due to the complexity of the manufacturing process, the promotion of this structure is affected.
Ball screw processing status
Ball screw processing methods are mainly divided into chip processing (cutting forming) and chipless processing (plastic processing). The traditional chip processing methods mainly include turning and whirlwind milling, while the chip-free processing methods mainly include cold extrusion and cold rolling.
Screw chip processing refers to the use of cutting and forming methods to process the screw, mainly including turning and whirlwind millingTurningTurning is the use of different turning tools or other tools on the lathe to process various rotating surfaces, such as inner and outer cylindrical surfaces, inner and outer conical surfaces, threads, grooves, end surfaces and forming surfaces, etc.
The processing accuracy can reach IT8-IT7, and the surface is rough. The value of Ra is 1.6-0.8. Turning is often used to process single-axis parts, such as straight shafts, discs, and sleeve parts.Whirlwind cuttingWhirlwind cutting (cyclone milling) is a high-efficiency thread processing method, suitable for large batches of thread roughing. Its process is to use a carbide knife to mill the threads at high speed.
It has good tool cooling and high production efficiency. advantage. For threads that do not require high precision, this method can be used to complete cutting. The thread processing method of milling threads from the workpiece with a shaped cutter head mounted on a high-speed rotating cutter head is named because of the high milling speed and the splashing of chips like a whirlwind. The accuracy of whirlwind cutting of trapezoidal threads is generally up to 7-9 (JB2886-81), and the surface roughness is Ra5~0.63.