TPT September 2007

T ube M ills: R olling & F orming M ethods

The evolution of quick change on mills

In this age of lean manufacturing, many tube and pipe producers face an apparent contradiction between just-in-time production and the long changeover times of their current mills. On large pipe mills, for example, changeover time is often measured in days and hours. It can be extremely expensive to affect any major time improvement if the tube mill is not supplied as original equipment. Therefore, the contradiction is tolerated and changeover improvement is focused mainly on incremental strategies. Preparation, training and the use of commercially available power can assist tools or material handling equipment. Tube or pipe production below 8" can open up more opportunities, and the smaller the tube or pipe the easier it is to accommodate a ‘Kanban’ production system.

T&H Lemont is the manufacturer of tube mills, rollforming machines and complete production systems, together with a whole range of other components (welders, cut- offs, entry equipment, accumulators, weld boxes and straightening systems). With a great deal of expertise in this area, T&H Lemont offers mill upgrades and advanced training and consulting. The company has established a number of evolutionary steps that a typical producer might encounter while focused on continuous improvement in changeovers. First and foremost is preparation – meaning, never being caught off-guard by a changeover, having all necessary hand tools and roll tooling available, and an experienced changeover crew at the ready. This usually requires a management driven zeal that cannot be delegated easily. Typically the cost of preparation is low and the payback large. After establishing the preparation in the working culture, a producer will next turn to a variety of incremental quick change methodologies. These can include: Power tools suspended (for easy one hand access) over the forming mill, sizing mill and cutoff Half nuts, jett nuts, and low profile nuts with ‘C’ washers to facilitate the release of the outboard retaining nuts and/or the outboard stand bolts – a goal of 30 seconds to release and • •

› A turkshead with quick change clevises

remove each outboard stand is not unreasonable A flip-top clevis on side stands for speed removal of the side rolls ‘T’ nuts/bolts, wrenches, thumb screws, and cam tighteners can be employed on the entry guide weld box, seam guide, ID scarf and ironing pass; the goal here is to eliminate or reduce the use of hand tools for changing/ adjusting these devices Single point adjusters with dial/ digital indicator that ties the inboard and outboard stands together for adjustment as a unit Weld box with quick change clevises Turks head with quick change clevises/motorized adjustments A quick change removal cutoff die mounted within the shoe

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After establishing preparation in the working culture, a producer will next turn to a variety of incremental quick change methodologies

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fi A quick change third-stand tube mill

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S eptember /O ctober 2007