Development of Spring Wire Feeder : Design for Spring Manufacturing with Coarse Spring Wire

Abstract: Lesjöfors Fjädrar AB is a spring manufacturing company. At the start of each manufacturing process when manufacturing cold coiled compression springs, the operators manually feed the spring wire from a reel that contains the raw spring wire, into the machine where the springs are made. This is a demanding process for the operators. The largest diameter of the spring wire today is 18 mm. Lesjöfors Fjädrar AB wants to increase the diameter to 22 mm and needs a new construction that allows feeding coarser spring wire from the reel into the machine. Trips were made to the factory in Lesjöfors where interviews and observations were made. A survey was conducted to gather information about the current process, as well as ideas for a new construction. With the information gathered, a requirement specification was made and approved by Lesjöfors Fjädrar AB. A brainstorming meeting was held at Rejlers Sverige AB in Karlstad with experienced constructors. The concepts generated during the meeting together with concepts generated alone were combined and evaluated using eliminations matrices and relative decision matrices. The highest ranked concept secures the spring wire with a hook inside the reel and extracts the spring wire with the help of a lift system. The lift system consists of a ball screw and an electric motor. After extraction, the spring wire is secured by two rollers before it is fed towards the machine by the electric motor currently installed on the reel. Along the way to the machine, the spring wire is steered/aligned by two pipes. The final concept was modeled in Autodesk Inventor Professional 2018 where the concept was designed in more detail. A stress analysis was conducted as a final step in the design phase. The final construction withstands the forces from the spring wire and makes it possible for Lesjöfors Fjädrar AB to start manufacturing cold coiled compression springs with a diameter of 22 mm, following the new working sequence made in this project.