A Servo Drive As A Torque Wrench

Moving away from handheld electric screwdrivers to fully automatic screwing - this has been the trend in mechanical connection technology for years. The aim is to ensure high product quality. This can only be improved if the manufacturer monitors and documents the actual torque of each screw.

This is possible with available products such as EC screwdrivers or electronic screwdriving systems, but the costs for the exact EC screwdriving technology with built-in torque or angle sensors range between 10,000 and 20,000 euros per system.

New screw application developed

In addition, the current-controlled tightening system calculates the torque based on the motor current and frequency and, due to various interference factors such as transmission losses, does not achieve the required accuracy when measuring the torque. This is exactly where ADT Fuchs saw a need for action and developed a new type of screw application. ADT stands for drive and compressed air technology. The family company was founded as a pure sales company for compressed air products and electrical drive technology. Today ADT Fuchs sells screwdriving technology from shut-off, battery-powered to EC screwdrivers. Due to strong demand, ADT finally created a special department in which control units, screw feeders, handling systems, automatic screwdrivers and special solutions are developed and manufactured according to customer requirements.The company now has an annual turnover of around two million euros.

Servo motor replaces gear

With partner Kilews, a manufacturer of handheld electric screwdrivers based in Taiwan, ADT has already developed screwdrivers with current control in the past. During the collaboration, a new type of screwdriver was created that displays the torque. This immediately reports when the set torque is no longer within the specified range and leads to better screwdriver control, quick exchange in the event of errors and longer calibration periods.

Based on this know-how, ADT wanted to develop its own electric screwdriver. The goal was a screwing system for robot applications or automatic screwing stations, which generates a repeatable torque without a gear and without a torque sensor. ADT found a competent partner in the supplier Panasonic Electric Works from Ottobrunn near Munich, because its servo motors proved to be optimal.

Screwing workplace

Ergonomic screw mounting ensures quality and efficiency

Screw system

16 tools - one control

Content of the article:

• Page 1: A servo drive as a torque wrench
• Page 2: Test setup achieves perfect results with torque accuracy

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