Ballscrew, also known as ball screw and lead screw, is a kind of steel ball that moves between the nut and the screw. It converts the sliding contact of the traditional screw into rolling contact and then moves the nut A transmission mechanical component that converts the rotary motion of the steel balls inside into linear motion. Ball screws have the characteristics of high positioning accuracy, long life, low pollution, and can be used for high-speed forward and reverse transmission and conversion transmission. Due to the above characteristics, ball screws have become the most popular positioning and measurement system in the recent precision technology industry and precision machinery industry. One of the important components. Basic introduction Chinese name: Ball screw application fields: basic concepts of mechanical processing, development history, structure, application industry, ball screw movement principle, processing status, turning, cyclone cutting, reasons why ball screws are not smooth, basic concept development history, people apply screws The history of transmission is actually not very long. Traditional screws have always been poorly positioned and easily damaged. It was not until 1898 that people first tried to insert steel balls between the nut and the screw to replace sliding friction with rolling friction to improve its poor positioning and easy damage. In 1940, ball screws were placed on automobile steering devices, which was a huge revolution in the application of ball screws, and gradually replaced the traditional Acme screw. Until recent years, ball screws have become one of the most widely used components in the industry. Originally, only advanced industrial countries such as the United Kingdom, the United States, Germany, and Japan were able to mass-produce ball screws. Since 1982, Ho Feng Precision Company has set up a factory in Tanzi, Taichung County to produce ball screws, officially opening an era in which Taiwan has the ability to produce such high-precision parts on its own. With development to this day, Taiwan now has the largest R&D and mass production capabilities in ball screws. It has already kept pace with other advanced industrial countries and has further become a major supply base in the world. This can be called one of the most significant achievements of Taiwan's mechanical components industry. Structure Ball screws are mainly composed of screws, nuts, steel balls, fixed seats, scrapers and return pipes. According to their different circulation systems, they are divided into external circulation type, internal circulation type and end plug circulation type ball screws. The structure of the ball screw is traditionally divided into two types: internal circulation structure (represented by circular reverser and elliptical reverser) and external circulation structure (represented by intubation). 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 installation and connection dimensions of the inner circulation structure are small; the installation and connection dimensions of the outer circulation structure are large. At present, there are more than 10 structures of ball screw pairs, but the more commonly used ones are: internal circulation structure; external circulation structure; end cover structure; cover plate structure. There are various shapes of internal circulation structure reversers, but the commonly used shapes are round and oval. Since the circular ball reverse channel is shorter, it is not as smooth as the oval structure. Now, the best reverser structure is an elliptical inner channel structure. Since the ball reverse direction does not pass through the screw tooth tip, it is similar to the outer circulation structure. Therefore, the chamfer error of the screw tooth tip on the ball reverse direction is eliminated. Influence. However, the complexity of the manufacturing process has affected the promotion of this structure. Since the development of industrial ball screws, it has been widely used in the positioning accuracy control of various industrial machinery, such as precision machine tools, industrial machinery, electronic machinery, and transport machinery. Important protagonist. In addition to the above-mentioned applications in machinery, it is also used in the transmission of computer disk drive starters, the adjustment of aircraft wing lift, the tilt angle control of propellers, medical X-ray fluoroscopy photography equipment, etc. The scope of application is extremely wide. Principle of ball screw movement 1. According to the national standard GB/T17587.3-1998 and its application examples, the ball screw (which has basically replaced the trapezoidal screw and is commonly known as the screw) is used to convert rotational motion into linear motion; or linear motion. It is converted into an actuator of rotary motion, and has high transmission efficiency, accurate positioning, etc.! 2. When the ball screw is used as the active body, the nut will follow the rotation angle of the screw and convert it into linear motion according to the lead of the corresponding specification. The passive workpiece can be connected through the nut seat and the nut to achieve the corresponding linear motion. Current status of processing At present, processing methods are mainly divided into chip processing (cutting and forming) and chipless processing (plastic processing).

Traditional chip processing methods mainly include turning and cyclone milling, while chipless processing methods mainly include cold extrusion, cold rolling, etc. Lead screw chip machining refers to the use of cutting and forming methods to process the lead screw, mainly including turning and cyclone milling. Turning is the use of different turning tools or other tools on a lathe. It can process various rotating surfaces, such as internal and external cylindrical surfaces, internal and external conical surfaces, threads, grooves, end faces and formed surfaces, etc. The processing accuracy can reach IT8-IT7, and the surface The roughness Ra value is 1.6~0.8. Turning is often used to process single-axis parts, such as straight shafts, discs, and sleeve parts. Cyclone cutting Cyclone cutting (whirlwind milling) is a highly efficient thread processing method, suitable for rough processing of threads in larger batches. The process is to use a carbide tool to mill the threads at high speed. It has good tool cooling and high production efficiency. High advantages. Threads with low precision requirements can be cut in one step using this method. The thread processing method uses a forming cutter head mounted on a high-speed rotating cutterhead to mill threads from the workpiece. It is named because the milling speed is very high and the chips fly like a whirlwind. The precision of cyclone cutting trapezoidal threads can generally reach level 7~9 (JB2886-81), and the surface roughness is Ra5~0.63. Reasons why ball screws are not smooth: In recent years, more and more ball screws have been used in a variety of machines to meet the needs of high-precision and high-performance equipment; ball screws have become one of the most widely used rotating elements. In NCN machinery, ball screws increase their positioning accuracy and extend their service life. In traditional machinery, ball screws have gradually replaced Aike nut screws. Ball screws are usually equipped with preload to eliminate backlash during mechanical operation. However, if the ball screw is improperly installed and does not run smoothly, it will not be able to demonstrate its high precision and long life. 1. Improper bearing installation: (1) The surface of the screw or nut bead is rough; (2) The roundness of the steel ball, screw or nut exceeds the tolerance range; (3) The lead error or pitch diameter of the screw or nut exceeds Tolerance range; (4) Improper assembly of the return pipe; (5) Uneven size or hardness of the steel balls; 2. Other foreign matter enters the steel ball track: (1) Packaging material fragments block the track: use a lot of packaging materials when shipping And anti-bag packaging of ball nuts and screws. If appropriate standard procedures are not followed when packaging or arranging steel balls, foreign matter or other debris objects may block the ball track, causing the steel balls to slide abnormally. The operation may even get stuck; (2) Processing debris enters the track. If the ball screw is installed without a scraper, the processing debris and dust can easily accumulate and block the ball track, resulting in poor smoothness, reduced accuracy or Reduce service life. 3. Overstroke: Overstroke will cause damage, dent, or even breakage of the return pipe, causing the steel balls to be unable to operate normally. Under such harsh conditions, the surface of the screw or nut beads may be peeled off. Problems caused by over-travel are most likely caused by machine settings, limit switch failure or crash. To prevent further damage to the ball screw, the ball screw must be inspected and repaired by the manufacturer before reinstalling it. 4. Damage to the return pipe: If the return pipe is severely impacted during installation, the return pipe may cause dents or the above problems. 5. Eccentricity: If the nut seat and the bearing seat are not concentric, a radial load will occur. If the deviation between the two is too large, it will cause the screw to bend. Usually, when the eccentricity is not very serious, it will not cause obvious bending, but abnormal wear will still occur. It continues to occur and rapidly reduces the accuracy of the screw. The higher the preload set by the nut, the higher the requirements for eccentric accuracy. 6. Improper combination of nut and nut seat: Inclination or eccentricity of the nut during installation will cause abnormal loads and cause voltage instability when the motor is running. 7. The ball screw may be damaged during transportation.