Machine for plastic fabric production

Detailed application description

Description of problem:

Big bags come in various sizes and end customers have a preference for synthetic fibres manufactured in-house. In preparation for the manufacturing process, these fibres are heated and stretched using several heated pulleys. LTN slip rings supply the power for heating the pulleys. They operate at very high rotational speeds and are subject to rapid and severe wear – especially at the contact brushes. Permanently reliable contact-making is an inherent problem with these highly stressed slip ring systems because mechanical abrasion and wear are inevitable at the sliding contact. A low-maintenance slip ring solution is therefore required. It must also be possible to monitor the brush life in order to restrict machine downtime to a minimum. Finally, the design should allow easy servicing, so customers can replace worn brushes themselves.

Description of solution:

LTN solved these problems with several modifications. Wear was reduced by using a wear-resistant brush material. All wear components form a complete module together with the mounting bracket and can be easily replaced by the customer. The remaining, cost-intensive portion of the slip ring (rotor, housing, bearing and electrical connection) can continue to be used, so that the costs for replacement are significantly lower.

Meeting the requirement for wear monitoring is more difficult. However, LTN offers a patented, integrated solution called DWD (Direct Wear Detection) which determines the condition of the slip ring based on the mechanical wear and provides a timely warning of failure (preventative maintenance). When a defined wear limit is reached, each brush produces an electrical stimulus independently of the others in a separate monitoring circuit via a potential-free contact. LTN’s direct wear detection system for slip rings is modular and suited for many different sizes in a wide range of applications.