Eichenberger produces niche products: In Switzerland, EAG is the only manufacturer of rolled ball screws, one of the few producers of coarse thread spindles worldwide. For decades, Eichenberger's technology has proven itself in ropeway construction: rolling the threads of the suspension bolts for thousands of ropeway gondolas. This technique is now also in the field of "normal" ball screw feeder collection as the example of high-tech knitting machines shows:In contrast to hand embroidery, not the needles are moved in the embroidery machine, but the entire fabric. The reason: To move the stretched fabric in the X and Y axes, it only requires one movement. If you wanted to control thousands of embroidery needles, thousands of actuators would be required. Specifically, this means that the fabric is moved back and forth as well as up and down with high speed and precision. In the "Epoca 1" 04-floor embroidery machine, these so-called gate movements, which are responsible for the fabric positioning, result in the highest embroidery quality.
The factors that spoke for the drive were accuracy, simplicity as well as cost and robustness for a ball screw drive (KGT), especially for the vertical travel. For these reasons, the ball screw drive (KGT 25 x 25) with four ball returns was chosen. The spindle is easy to install: the gearbox is integrated in the nut body. The turning into a longitudinal movement is carried out precisely and without play.
But an "ordinary" KGT over 2 m long would not achieve the required freedom of play. Because the mother always has a certain game, that's what physics wants. In most applications this is irrelevant. In special cases, this game is devastating. This is also the case in the embroidery machine: the spindle nut moves up to move the fabric - but a little too much, the control "says": two micro-partial steps back. If there was too much "game in the game", the setbacks go nowhere. The result is an unusable pattern. This would be particularly important if the direction of movement were reversed. If accelerations of more than 1 g occur when moving the nut in the Y axis, the nut flutters on the spindle.
In order to cancel this game, the usual system with two nuts clamped against each other was not used, but a special construction is used: a single nut that combines a very short design with high rigidity. The preload is generated on the spindle using a special thread profile on a Gothic basis.