FEATURE Drives, Controls & Motors
Servodrives help protect chair castors and cut packaging cost
D
esigning an automated system to fi t up to 36,000 protective caps per day onto offi ce chair castors might seem an unusual and
challenging application for servo drives and controllers. However, it’s a good example of how today’s motion control and automation technology can help manufacturers to increase productivity and reduce costs. Bulky objects such as offi ce chairs require cumbersome cardboard packaging to ensure they are delivered to customers without any damage caused during transportation. Drives and motors specialist Yaskawa played a key role in the development of an automated system, specifi cally designed to fi t protective plastic caps onto the castors with its Sigma-7 series servo-drives and a SLIO-series controller.
Office chairs Gross+Froelic is an offi ce chair and furniture castor specialist who wanted to explore the benefi ts of latest automation technology for its manufacturing processes, such as introducing a system that applies ring-shaped protective caps. Any bulky furniture item with castors doesn’t have to be carried – although pushing a typical offi ce chair all the way to a customer is not an option. However, once delivered they can certainly be wheeled to their fi nal destination, but, must arrive without any scratches or damage, hence the need for plastic protectors.
The castors consist of two individual wheels with a protective cap pressed onto each and it’s now a process that can
be automated, operating at high speed. Gross+Froelich uses a machine made by Aramis that operates with cycle times of just 2.4 seconds, following its re-design using latest servo technology.
Depending on the castor model, it’s 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 about 10,000 caps more than the machine managed before its re-design.
Key factors for 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.
It would have been impossible to achieve the higher speeds with pneumatic drives due to the mechanical stresses being so high. Furthermore, the levels of compressed air consumption are much lower, which has reduced operating costs.
Right: Yaskawa Sigma-7 drive
Yaskawa’s Sigma-7 series was the choice for the electric drives having already proven themselves in many similar applications. 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, Aramis, to turn to Yaskawa. Aramis worked with Yaskawa’s automation specialists to retrofi t the machine for fi tting 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 whilst a pneumatic linear unit with a gripper transfers the plastic cap from the separation unit to the nest of the rotary table. An electrical cylinder driven by 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, with a third servo drive controlling the horizontal movement. The fi nished parts are sent down a chute, where the cap-protected wheels are transferred to a lattice box to be transported to the fi nal assembly stage.
CONTACT:
Yaskawa Sigma-7 drives in action, capping office chair wheels
26 April 2023 | Automation
Yaskawa
www.yaskawa.co.uk
automationmagazine.co.uk
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