Ball screw pair equipment

**Ball Screw Pair Equipment** Home > Bearing Knowledge > Ball Screw Machine Ball screw pairs are essential components in mechanical systems, serving as a type of screw transmission element that uses balls as rolling elements between the screw and nut. These systems come in various configurations, with the main distinction being the method of ball circulation: external and internal. External circulation typically uses more through-type designs, while internal circulation often features lug groove types. Based on the cross-sectional shape of the thread path, ball screws can be categorized into single-arc and double-arc types. Double-arc screws offer greater axial stiffness compared to their single-arc counterparts, which is why they are widely used today. In terms of preloading methods, ball screw pairs can be classified into several types, including single-nut no pre-tightening, single-nut displacement lead pre-tightening, single-nut radial pre-tightening, double-nut washer pre-tightening, double-nut differential tooth pre-tightening, and double-nut thread preloading. Among these, double-nut washer pre-tightening is commonly used in CNC machine tools, with a typical preload of about one-third of the axial load. Compared to sliding screw nut pairs, ball screw pairs offer numerous advantages such as high transmission efficiency, high sensitivity, stable operation, low wear, long life, and the ability to eliminate axial clearance. These benefits make them ideal for use in the feed systems of small and medium-sized CNC machines, as well as in short-stroke (6 meters or less) feed systems of heavy-duty CNC machines. To ensure optimal performance, the feed system of a ball screw pair must achieve high transmission rigidity. This involves not only strengthening the rigidity of the screw and nut but also ensuring proper layout and support. The nut seat and support seat must have sufficient rigidity and accuracy. Increasing the contact area between connected parts can enhance rigidity and strength, and modern machine tools often integrate the nut seat or support base directly into the machine body to improve structural integrity. Axial stiffness is also crucial, and selecting the right bearing plays a key role. In China, two common approaches are used: combining radial and tapered bearings, which is simple but lacks axial stiffness, and using thrust or radial thrust bearings with radial bearings, which improves axial stiffness but increases friction and heat. Specialized ball screw bearings are now available, designed to handle large axial forces with an increased contact angle of 60 degrees, more balls, and smaller diameters, significantly improving axial stiffness. There are four common installation methods for ball screw pairs: 1. **Double Push – One Free**: Used for short lead screws, where one end is fixed and the other is free. 2. **Double Push – One Support**: One end is fixed, and the other is supported, allowing for some axial movement. 3. **Double Push – Double Push**: Both ends are fixed, providing maximum rigidity and enabling pre-tensioning. 4. **Screw Fixed – Nut Rotates**: The nut rotates while the screw remains fixed, preventing critical speed issues and reducing vibration. Protective measures are essential for ball screw pairs to prevent contamination from dust and chips. Protective covers, spring steel sleeves, and elastic or labyrinth seals are commonly used. Touch seals offer better dust protection but add some friction, while labyrinth seals reduce friction but may not protect as effectively. Lubrication is vital for maintaining performance and longevity. Lubricants can be either oil or grease, with grease typically applied to the nut and thread raceway, and oil delivered through oil holes. Grease should be replaced every six months, while oil should be topped up before each operation. High-speed machining on CNC machines requires advanced ball screw systems. These systems are characterized by high power, precision, and surface quality, widely used in aerospace, automotive, mold making, and electronics. To achieve high-speed performance, manufacturers focus on increasing speed, lead, and number of threads, optimizing ball movement, using hollow cooling techniques, and employing the screw-fixed, nut-rotating method. Japan and Switzerland lead in this field, with speeds reaching up to 90 m/min and accelerations of 15 m/s². Ball screw technology continues to evolve, offering reliable, cost-effective solutions for many applications. Whether in standard or high-speed CNC machines, ball screws remain a critical component of modern manufacturing. **Related Bearing Knowledge** High-carbon chromium bearing steel bar after rolling control and cooling spheroidization process Low-noise bearing analysis: Discriminate NTN "angular contact ball bearing" fault damage adjustment pre-tightening method SKF imported bearing repairing guidelines and methods of magnetic suspension bearings This article is linked to http:// Please indicate China Bearing Network http:// Previous: The manufacturing process of bearing steel balls Next: Carefully prevent the top ten factors affecting the life of tires

Pillow Blocks

Pillow block, also known as plumber block, which are bearing housings supplied without any bearings and are usually meant for higher load ratings and a separately installed bearing.

Pillow block or Plummer block housings can be used with high-capacity spherical roller bearings or self-aligning ball bearings. They are manufactured from high-strength cast iron as standard but are also available in cast steel or spheroidal graphite cast iron. The housings have a re-lubrication facility and can be used with either oil or grease lubrication.

Pillow block or Plummer block can be 1 or 2- piece split types held together by two or four cap bolts. Most bases provide two or four mounting bolts. Most blocks are of Class 30 gray cast iron. For more strength and ductility, usually they can be furnished in ductile iron or cast steel.

We have specialized in producing US/EURO standard bearing housings more than 10 years, could help to design the bearing housing or produce the Bearing Housing according to your requirements. (OEM accepted)

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