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DRIVES, CONTROLS & MOTORS
Driving automateD manufacturing servo drives and a SLIO-series
Using its Sigma-7 series
controller, YASKAWA has played a key role in the development of a
fast automated system specifically designed to fit protective plastic caps onto castors of office
chairs. Here the company looks into the application
O
nce delivered to the customer, ’bulky’ furniture items with castors can be wheeled to their final destination. They must, however, arrive without any scratches or damage, which is why
plastic protectors are needed. So, office chair and furniture castor specialist, Gross+Froelich, wanted to explore the benefits of the latest automation technology for such manufacturing processes as applying the ring-shaped protective caps. Designing an automated system to fit up to 36,000 protective caps
per day onto office chair castors might seem an unusual application for servo drives and controllers. It is, however, a good example of how today’s motion control and automation technology can help manufacturers to increase productivity and reduce costs. The castors consist of two individual wheels with a protective cap pressed onto each.
an increase in proDuction speeD Gross+Froelich uses a machine manufactured by ARAMIS which can, following its re-design using the latest servo technology, operate with cycle times of just 2.4 seconds. Depending on the castor model, it is now possible to fully apply up to 36,000 protective caps automatically to the castor wheels over 24 hours of operation. This is an increase of around 10,000 caps more than the machine managed previously. Two key factors helped to achieve shorter cycle times. Firstly, the
capacity of the rotary indexing table for the plastic caps was increased from four receptacles to eight; and, secondly, three of the pneumatic drives installed in the machine were replaced with the more dynamic Yaskawa Sigma-7 series electrical servo drives. According to the company, it would have been impossible to achieve the
higher speeds with pneumatic drives due to the mechanical stresses being excessively high. Furthermore, the levels of compressed air consumption are much lower which has reduced operating costs. Yaskawa’s Sigma-7 series of servo drives was chosen as these had
already proven themselves in many similar applications and had impressed ARAMIS, the machine builder. Features such as rapid commissioning, high production capacity and maximum operational reliability, in addition to the responsiveness of the AC motors, were the key factors for the machine builder. However, their extremely compact dimensions and quiet operation were also important.
Drive solutions The machine builder and other key suppliers worked together with Yaskawa’s automation specialists to retrofit the machine for fitting the protective caps. A total of three 400V servo axes, each with 400W of power, are now in use in the machine. One drive is responsible for the horizontal movement of the feed while a pneumatic linear unit with a
MARCH 2023 DESIGN SOLUTIONS 17
gripper transfers the plastic cap from the separation unit to the nest of the rotary table. An electrical cylinder driven by a second
servo drive presses the cap against the chair roller, while a compression force sensor detects the surge in force when they engage. Together with the absolute position sensor on the servo motor, it detects whether the pressing process was successful, while a third servo drive controls the horizontal movement. The finished parts are sent down a chute where the wheels, which are now protected by the caps, are transferred to a lattice box so they can be transported for final assembly. The drives offer high resolution (with an
integrated 24-bit absolute encoder) and high dynamics along with vibration suppression, as well as suppression of machine resonance frequencies and a tuning-less function for simple start-up – all integrated into the compact servo amplifiers.
Yaskawa T: 0330 678 1990
www.Yaskawa.co.uk
Yaskawa Sigma-7 series electrical servo drives
FEATURE
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