Ball Screw Assemblies
Ball Screw Assemblies
It is immediately apparent that a ball screw cannot be described as a simple tool. Instead there are many parts with the whole thing being called a ball screw assembly. The central parts of a ball screw assembly are the pieces called the nut and the screw. The nut moves linearly on the screw regardless of which of the two parts is moving. In general the screw’s turning action is changed into the straight line movement of the nut, or the movements may be swapped a process that is called back-driving.
Ball screw assemblies cannot be seen as being extremely complicated. There are ball bearings inside the nut, and these can rotate through the assembly. The screw resembles a carpentry screw, featuring threads. Within the nut there are matching threads along it which create tracks for the ball bearings to follow. When the screw is turned this causes the ball bearings to move, which makes the nut travel along the screw. The ball screw assembly is completed by a deflector that ensures the ball bearings continuously return to the top of the nut. When a ball reaches the bottom of the nut the deflector reverses its motion, sending it back to the top of the nut. This is a circuit, with a continuous circulation of ball bearings contained behing the casing of the nut. In many ways this is the basis of the ball screw assembly.
You can estimate the lifespans of ball screw assemblies by counting the threads on the screw and the number of threads in the barrel of the ball nut. On each occasion that equates to a complete movement of the nut along the screw, each thread on the screw has had each ball bearing travel along it once. However, the threads within the nut may have been run over by the ball bearings a number of times which of course is dependent on the relative screw length. It can be seen that the proportional difference between the nut thread count and the screw thread count will tell you the amount of extra work done on the ball nut surface which will give an approximation as to the relative lifespan of the nut in comparison to the ball screws. Various ball screw assemblies should last longer than others, as can be calculated using the relative thread counts.
Ball screw assemblies cannot be seen as being extremely complicated. There are ball bearings inside the nut, and these can rotate through the assembly. The screw resembles a carpentry screw, featuring threads. Within the nut there are matching threads along it which create tracks for the ball bearings to follow. When the screw is turned this causes the ball bearings to move, which makes the nut travel along the screw. The ball screw assembly is completed by a deflector that ensures the ball bearings continuously return to the top of the nut. When a ball reaches the bottom of the nut the deflector reverses its motion, sending it back to the top of the nut. This is a circuit, with a continuous circulation of ball bearings contained behing the casing of the nut. In many ways this is the basis of the ball screw assembly.
You can estimate the lifespans of ball screw assemblies by counting the threads on the screw and the number of threads in the barrel of the ball nut. On each occasion that equates to a complete movement of the nut along the screw, each thread on the screw has had each ball bearing travel along it once. However, the threads within the nut may have been run over by the ball bearings a number of times which of course is dependent on the relative screw length. It can be seen that the proportional difference between the nut thread count and the screw thread count will tell you the amount of extra work done on the ball nut surface which will give an approximation as to the relative lifespan of the nut in comparison to the ball screws. Various ball screw assemblies should last longer than others, as can be calculated using the relative thread counts.
