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They work together, communicate and monitor each other: QST spindles
and PST presses show what’s possible for the future

The most modern tightening control unit has advanced another step. PowerMacs 4000 equipment from Atlas Copco had already brought tightening to perfection thanks to an intelligent monitoring system and on-time error detection. Now we’ve taught PowerMacs 4000 equipped with QST spindles to communicate and work with PST presses. The devices work together and even monitor each other. The press pushes parts to a designated location, and then sends an echo to the spindle, which checks the fit and tightens the joint. If the press fails, the nutrunner provides defect notification and vice versa. Is that even possible? At the Revoz automotive plant in Slovenia, it is.

The Revoz assembly line in Slovenia puts out the Clio and Twingo models for Renault. The latest models on the line are the new Twingo and Smart for 4 (in cooperation with Daimler). Modernization that allows their mass production will be completed soon. Unique equipment from Atlas Copco will be part of the station for installing shock absorbers.

Better monitoring of joints and spindles
Revoz is one of Slovenia’s most important companies. It belongs to Renault and previously used the same press tools as other Renault plants, built from electric motors and added position sensors. Now, however, they are preparing a new shock absorber installation station for production of new models. “And we needed new equipment for that. It had to be able to monitor press force and travel during that individual process. That’s not possible with a system used so far,” explains Matjaž Močivnik of Atlas Copco.

Another issue they wanted to improve with new equipment was inspection of tightening spindles. In the past they mostly used spindles and assembly tools with one torque transducer, where inspection is needed once per shift. “The tightening spindles we delivered have double transducer so they monitor each other and the risk of deviation is truly minimal. Thanks to that, external measurement inspections are no longer needed so often,” explains Močivnik, adding that now Revoz employees need to check the spindles once a year. And that is what Renault’s internal guidelines call for.

A unique combination of a press and nutrunner

Considering all the parameters requested, we recommended a total of three PowerMacs 4000 units for the customer. One is equipped with a PST system, and the other two have QST tightening spindles with double transducer. PST is an electromechanical assembly press with excellent programming and monitoring options. In the Slovenian auto plant, it will help to assemble shock absorbers for the new models. “The PST system presses the spring into the required position. Then it sends information to the nutrunners, which secure the spring in position,” explains Matjaž Močivnik.

Our nutrunners allow Revoz to monitor the tightening process as requested. Problems positioning the spring are recognized even before tightening. If the system records a tightening defect, the spindle loosens the joint again and the PST press loosens the spring for removal. “Process monitoring is almost constant. If, for example, a spindle does not untighten a defective joint completely for some reason, the press sets off an alarm,” adds Močivnik.

This kind of press/spindle combination is completely new to us. “We thought it would be possible for both machines to work together. And thanks to our Slovenian partner, we have shown that not only is it possible, but it is also efficient and reliable,” says Matjaž Močivnik. He says that in the future this won’t be confined to just one assembly line. “The equipment has a lot of potential. It brings together all the advantages of our PST press and the modern QST tightening spindles,” he adds.

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