Ball Screw Shaft

Ball screw shaft is the rotary motion into linear motion, or linear motion into rotary motion of the desired product. Ball screw by the screw, nut and ball composition. Its function is to convert rotary motion into linear motion, which is a further extension of the ball screw and development, the importance of this development is that the bearing moves into a sliding operation from the scroll. With little friction, ball screws are widely used in various industrial equipment and precision instruments.

1.Brief introduction

A.Is the rotary motion into linear motion, or linear motion into rotary motion of the desired product.

B.Ball screw by the screw, nut, ball, preload tablets, inverter, dust components. Its function is to convert rotary motion into linear motion, which is a further extension of the screw Actmix and development, the importance of this development is that the bearing moves into a sliding operation from the scroll. With little friction, ball screws are widely used in various industrial equipment and precision instruments.
Machine tools and precision ball screw is most commonly used mechanical transmission components, its main function is to convert rotary motion into linear motion, or torque into axial forces repeatedly, while both high-precision, reversibility and high efficiency characteristics.
Ball main parameters: nominal diameter and lead.

2.Principle

A.In accordance with the national standard GB/T17587.3-1998 and application examples, ball screw (has replaced trapezoidal screw, commonly known as screw) is used to convert rotary motion into linear motion; or linear motion into rotary motion of the actuator , and has a high transmission efficiency, accurate positioning, etc.
2, when the ball as an active body, the nut will screw with the corresponding specifications in accordance with the rotation angle of the lead into linear motion, the workpiece can be passive and nuts nut seat, in order to achieve the corresponding linear motion.

3.Application

Ball bearings to adapt to a variety of purposes, providing a wide range of standardized products. Widely used in machine tools, ball circulation method with circulating conduit type, circulator type, cover type. A positioning preloading preloading (double nut method, bit preload), constant preload. Can be selected at the appropriate type. Screw with precision grinding, precision ball screw (from CO-C7 accuracy is divided into six levels) and by high-precision cold rolled ball screw bearings forming processes (accuracy is divided into three from the C7-C10 levels). In addition, users need to cope with the situation of delivery, there has been carried out on the shaft end processing of finished products, are free to chase on the shaft end for processing semi-finished and cold-rolled ball screw bearings. As part of this bearing peripheral parts necessary for the use of screw support units, nut bearing, locking nuts, etc. have also been standardized for the user to choose to use.
Ball bearings are accumulated over the years technology-based products, from the material, heat outside the grounds, manufacture, inspection to shipping, are based on strict quality assurance system to be managed, it has a high reliability.

4.Use

A, high DN value Ball: High-speed machine tools, High Speed ​​Machining Centers.
B, cover ball screw: Fast handling systems, general industrial machinery, automated machinery.
C, high-speed ball screw: CNC machinery, precision machine tools, industrial machinery, electrical machinery, high-speed machinery.
D, precision ground ball screws: CNC machinery, precision machine tools, industrial machinery, electrical machinery, transportation machinery, aerospace industry, other antenna actuator, the valve switching devices.
E, Rotating Nut (R1) Series Ball: semiconductor equipment, industrial robots, woodworking machines, laser processing machines, conveying devices.
Rolled Ball Screws Level: low friction, smooth operation of the advantages, but quick delivery and low prices
Heavy Ball: All-electric injection molding machines, stamping machines, semiconductor manufacturing equipment, heavy-duty brakes, industrial machinery, forging machinery

5.Type

 Common cycle in two ways: the outer loop and inner loop. Balls in the cycle of the screw is sometimes referred to as the outer loop disengagement; always kept in contact with the screw is called inner loop. Ball called a column for each closed loop, closed loop contained within each ball number is called the lead lap. Each circulating ball screw nut with two, three, four, five and so are several, and each column only lap; outer loop 1.5 turns per column, 2.5 and 3.5 turns, such as several laps.
A, the outer loop: the outer loop is the ball in the cycle after the end of the outer surface of the nut through the spiral groove or screw nut among intubated return to re-enter circulation. Shown in Figure 2-3, the outer loop circulating ball screw nut at the time of return methods are mainly cover type, tube and spiral trough. Common external circulation method Figure 2-3 (a) cover formula; (b) tube type; (c) the spiral slot as 2-3 (a) shows the end cap type, the nut on the processing of a longitudinal bore as the ball return channel nut cover both ends of the return of the ball on the opening mouth, the ball will enter return pipe, form a cycle. Figure 2-3 (b) shows the tube type, it is used as a return duct elbow, this structure technology is good, but due to the pipeline projecting nut body, the larger radial dimension. Figure 2-3 (c) shows the spiral slot, which is milled out of the nut on the outer spiral groove, the groove ends of the through hole drilled with the tangent screw raceway, the return channel is formed, this structure radial dimension than the tube structure is small, but the manufacture of the more complicated. Outside the outer loop recirculating ball screws structure and manufacturing process is simple, widely used. The disadvantage is difficult to do raceway smooth seams, affecting the smooth ball rolling.

B, the inner circle: the inner loop is shown in Figure 2-4 ball. Circulating balls are made of reverse loop is implemented, there are two types of inverter. Figure 2-4 (a) shows a cylindrical projection key reverser embedded nut of its cylindrical portion, the end portion on a reverse tank 2. Reverse cylindrical outer surface and the groove by the upper end of a round key positioning to ensure alignment of thread rolling direction. Figure 2-4 (b) shows the reverse oblate insert, inverter is generally round flat key insert, the cutting insert slot embedded nut, the end portion opened reverse tank 3, the outer contour of a positioning insert. Compares two kinds of reverse, which is small in size, thereby reducing the radial dimension of the nut and shorten the axial size. However, this type of inverter and the nut on the outer contour of the notch size with high precision. Pictured cover circulation for reference only.

6.Category Selection

Ball screw nut, according to the cycle of the ball can be divided into: Bending type, circulator type, cover type. Features of these three round-robin fashion.
A, bending formula: (SBN, BNF, BNT, BNFN, BIF and BTK-type) these models, the search to.
B, circulating guide vane: (HBN type) These models are the most typical nut, let the ball through the use of bends through the line cycle. Ball screw shaft in a trench from scooping into the pipe, and then returned to the trench, infinite motion.
C, the circulator formula: (DK, DKN, DIK, JPF and DIR-type) These models are the smallest nut ball through the circulator to change the direction of travel, crossed back into place screw shaft diameter, do an infinite loop movement.
D, cover type: (SBK, SDA, SBKH, WHF, BLK, WGF, BLW, WTF, CNF and Model BLR)
These models are the most suitable for high-speed feed nut. Ball use cover, screw shaft from the groove to be picked up through holes in the nut through the hole back trench infinite motion.

7.Feature

A sliding screw vice and the driving force compared to 1/3
As the ball screw nut screw between the screw shaft and the ball was doing a lot of rolling motion, they are able to get higher efficiency of movement. Sliding past compared to ball screw drive torque of 1/3 or less, that to achieve the same movement as the result of the power needed to use the scroll ball screw 1/3. Helpful in saving.
2, ensure high-precision
Ball screw is generally used the world's highest level of consistent production out of machinery and equipment, especially in the grinding, assembly, inspection of the process plant environment, temperature, humidity were strictly controlled, because a sound quality management system so that accuracy can be fully guaranteed.
3, the micro-feed may
Ball screw is the use of ball movement, so very small starting torque, does not appear like sliding movement creeping phenomenon, to ensure accurate micro feeding.
4, no backlash, high rigidity
Ball screw can be added with preload, since the pre-axial clearance can achieve negative pressure, then get a higher rigidity (the ball within the ball through to add to the pressure, and other mechanical devices used in practice, due to the repulsion ball nut can enhance the rigidity of the Ministry).
5, high-speed feed may
Ball, sport, high efficiency, small heat, so you can achieve high-speed feed (movement).
◎ precision tolerance: P5. P7

8.Protection

Bal lscrew shaft  protection
Lubrication of ball screw can be used to improve the wear resistance and transmission efficiency. Lubricants are divided into two major categories of lubricants and greases. Lubricating engine oil, turbine oil 90 to 180 or 140, spindle oil. Grease can be lithium based grease. Grease applied to the threads and install the nut raceway housing space, while oil injection hole through the nut on the housing space.
Rolling friction ball screw drive and other components, as long as the abrasive particles and chemicals to prevent active substances into, these components can be considered virtually no wear in the case work. However, if the fall in the raceway dirt, or dirty oil will not only impede the normal operation of the ball, and the sharp increase in the wear and tear.
Usually felt ring for sealing the nut, the thickness of the felt ring of 2-3 times the pitch, and the threaded bore formed shape to tightly wrap the screw and nut or the sleeve into the groove at both ends hole. In addition to using a soft felt seals, you can also use oil-resistant rubber or nylon material. Since direct contact seals and screw, so dust is better, but also increases the friction ball screw nut torque. To avoid this friction torque, the rigid plastic may be used non-contact labyrinth seal, and the screw threaded bore formed in the shape of the opposite roller, and leave a certain gap.
For the exposed screw, just generally spiral belt, retractable sleeve, tapered sleeves and folding plastic or leather in the form of protective cover to prevent dust and abrasive particles adhered to the surface of the screw. In addition to the guide rail similar protective cover, the protective cover these types of nut connected to one end face of the ball, and the other end is fixed to the bearing seat of the ball screw. This can be more firmly it.

Taian Haishu Machinery Co.,Ltd.

Technology Feed

2013-07-01