Konceptframtagning av lyftverktyg för byte av stödrullar i varmbandhaspel

In the hot-rolling mill VVV04 in Sandvik, there is down coiler unit that rolls the hotrolled strip. The down coiler unit has four wrapper rolls, these rolls acts as a support by pressing the hot-rolled strip over a major central axis. These wrapper rolls need to be replaced about once a year due to wear and tear, each roll weighs approximately 380 kg. at present, the wrapper rolls are lifted with lifting straps and lever block chain hoist. A new lifting tool is needed due to the current method of replacing the wrapping roll is not considered sufficiently safe from the point of view of the working environment. A literature study was carried out to assess the requirement to be met for the lifting tool to obtain CE-marking. The literature study also investigated ergonomic methods for assessing working positions. Development of the concept was done with a simplified version of the method described by Karl T Ulrich and Steven Eppinger. The concept was divided into three parts; grip, movement and attachment. The concept was created using a combination of brain writing and brainstorming over several meetings. Concept selection was done using a selection matrix called Pugh’s Matrix. To gain an understanding of the risks mechanics face when replacing wrapper rolls, an asis analysis was conducted. The developed concept was checked with FEM analysis and with manual calculations and showed very good safety margins. The work positions that are evaluated in the literature study are not improved from OWAS point of view, but several of the work steps are eliminated and made more efficient, which leads to increased safety for the mechanics, the lifting tool introduces a new working position with a lower risk. This lifting tool improves the working environment of the mechanics by increasing safety when changing the wrapper rolls and reducing physical stresses on the mechanics. Further work is to assess which material is most suitable and what changes to the concept are needed to simplify the production of the components.