Ever higher precision and higher speeds: These are key trends for linear actuators. In this context, an important role in the cooling. NSK has developed already in the 80er years ago the first series with integrated cooling. There was a hollow bored spindle shaft (hollow shaft spindle) used, was passed through the cooling liquid. Now the next step of development is done: NSK provides high-speedBall Screws before, in which the parent is cooled.The impetus for the development was given by customers from the tool and plastic machine construction. You have to meet ever higher precision requirements so that the machines e.g. B. aircraft components with extremely high dimensional accuracy or plastic components such as cell phone housing with extremely thin walls. A constant temperature in the machine or in the tool is one of the prerequisites for this precision, because temperature differences can lead to dimensional changes, distortion or other quality losses. If particularly high demands are made, ball screws without cooling come up against limits. A system in which the nut is also cooled, on the other hand, enables temperature control to be even more precise, especially since the nut holder is then also cooled.
The known problem that the cooling caused by the contraction of the material affects the bias of the mother, could be solved. After extensive testing, the NSK developers have determined a preload level that does not change as a result of cooling. Compared to the cooled hollow shaft spindles, the ball screws with cooled nut have at least as good, in many cases even significantly better cooling performance. Especially in high-speed applications with short strokes, the cooling effect is significantly higher.
Thus, the new type of cooling is particularly suitable for machines that perform relatively small movements with high speed and short cycle time. This applies, for example, to many machine tools that process automotive components, as well as to injection molding machines that produce plastic parts with high dimensional stability requirements.
The cooled nut series 1: 1 can be replaced with existing cooled spindle series because the dimensions are identical. In addition to the technical advantages, the new ball screws offer a significant economic advantage: They can be manufactured cost-effectively, because it is much easier to introduce a hole in a nut than to manufacture a spindle in hollow shaft design. This advantage benefits the user, who also benefits from the fact that cooling can be easily integrated into existing cooling systems. The cooled nut body can be supplied in the shank diameters 40, 45, 50 and 63 mm. Depending on the spindle shaft, slope variants with 16, 20, 25 and 30 mm are available.