TPT September 2007

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

key points and the ability to weld at slow speeds while jogging Elimination of the outboard stand on the ironing pass A discretionary next step in improvement for some producers might be the automation of the single point adjustors, usually through specialized servo controllers for each set of stands. This approach usually employs a presetting computer to record last set positions and interface between new presets for the next set of tooling or product. Following an extreme set of incremental adjustments, a producer would then most likely be faced with a quantum leap to rafting of tooling stands and appliances. This can be carried out on existing mills but the expense is often close to that of a new mill. This is usually not considered unless the expense is considerably less than that of a new replacement mill installed. A clear trend in new mill projects below 6" is rafting. This is because the initial cost is small compared with the rest of the total project. A range of variations on rafting are worth reviewing for anyone considering future specifications: •

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A producer would then most likely be faced with a quantum leap to rafting of

tooling stands and appliances

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Simple rafting, over posts, configured to maintain alignment from tool-set to tool-set (often employing lifting rings attached to the raft for crane removal or with design cavities for forklift access) Simple rafting requires a basic means to disconnect the drive source so quick release universals are required Third stand rafting, as the name implies, describes a third stand (driven stand) which is mounted to the mill base, behind the inboard stand (raft mounted). It employs quick coupling techniques to power the raft stands. In this arrangement, various creative scenarios can be applied to move the raft about. These include: Raft removal by crane Raft removal by forklift Raft removal to the cart system that also ferries in the change raft Raft removal to the cart system that rotates to deliver the change raft Other options (in development) Advanced third stand rafting that includes a self aligning system for third stand hubs to accommodate pre- setting the offline raft It is important to recognise that there are many ideas for mill changeover improvement, and varying effects of mixing and matching incremental and quantum improvements. It is difficult to be certain of the results in terms of improved changeovers, whether it is 2 hour or as little as 15 minute changes. As a note of caution to those embarking on a quick change improvement program, it is vital that preparation is the first methodology to be mastered. Otherwise, the results from all the other small and large scale improvement efforts may be inconsequential. • • • 1. 2. 3. 4. 5. •

› Quick change flip top side pass design

A more innovative approach to quick mill changeover is to consider some paradigm shifters, which can help significantly, as long as they do not interfere with product quality. Some ideas include: Universal breakdowns to remove the necessity for changing out the rolls, which may require a change in tool design philosophy Elimination of the seam guide, which may necessitate more precise alignment of the mill Practice and perfection of end-to-end threading of the mill, at a fast jog or slow run. This may require precise alignment, use of lead-in-appliances at • • •

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fi Quick change third stand mill with hydraulic raft disconnect

T&H Lemont – USA Fax : +1 708 482 1802

Email : sales@thlemont.com Website : www.thlemont.com

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S eptember /O ctober 2007