TPT March 2022

AR T I C L E

Fives

Fully automated, quick, safe and precise frontal tube mill changeover solution By Luca Ferraguti, product manager, Fives OTO

upper roll can be individually replaced from the top for the fastest format change. This way, the changeover process is fully automated and is carried out without any need to lift the work pieces above the mill. It doesn’t require a higher building any longer. Furthermore, the carriages can be flexibly arranged according to the plant layout by taking advantage of the available space. Changeover process The carriages’ use makes it possible to prepare the new cartridges while the mill is completing the previous production cycle and to remove the cartridges for rolls changeover, after the mill has started its new production run, thus saving time. It also avoids the use of cranes and related issues regarding safety and height clearance. In the initial condition, the driven stands are in their working set-up, for example: the universals are coupled and the shaft bearing supports and side roll supports, if present, are engaged into the screws of the adjuster jacks. Empty changeover carts stand in front of the relevant mill section ready to receive the cartridges with the rolls. As the changeover sequence starts, the driven roll shafts and side rolls supports are automatically set to the change position and the hydraulic locks of the top jacks are released, leaving the upper bearing housings free, to disengage from the jacks, while the universals are rotated to the change position. At this point the roll cartridge assembly slides out of the holder, the universals are disengaged, and cartridges are loaded directly onto the carriage. The carriage holding the incoming cartridges, may or may not be the same, depending on the configuration. The carriage can now translate to align the incoming cartridges in front of the ready-to-load holders. If the new cartridges are on the same carriage, it will only take one step forward, while if they are on a different one, depending on the configuration, both the carriages will move accordingly. The previous sequence is then repeated backwards until all the cartridges are back on the stands, the couplings and the screw jacks are engaged and the roll positions are set automatically according to the relevant recipe, thanks to the Mill Manager software module. The side pass stands’ cartridges, including slides and roll clevises, are replaced as a complete assembly.

Safety and short downtimes are key factors when it comes to tube mill changeovers, and customers expect ever shorter downtimes, with greater safety and as little manpower required as possible. Fives, an international engineering group, developed ETF, a frontal quick-change system with greater flexibility, granting a totally automated crane-free operation. The ETF system is dedicated to large mill operations, offering a quick, safe, precise and flexible changeover solution. Time consuming operation Mill changeover procedures are the most time- and labour- intensive steps in tube production. Whenever one or more rolls must be changed according to the new tube format, or due to rolls regrinding, the mill must be stopped and production is switched off for a certain time. On large or heavy mills the stands cannot be replaced at a time, swapping the rafted stands as happens on small mills, due to their excessive weight, therefore the stands are provided with replaceable roll cartridges that can be substituted as a whole. In many still running mills a common way to do that is to replace either the whole of stands or each stand cartridge one by one using a crane from above. It’s clear that this process is very time consuming, may create safety issues due to a crane’s work and requires a lot of skilled labour to carry the task out while ensuring correct alignment when replacing the stands or cartridges. In addition, a considerable height space is necessary to lift the pieces of equipment over the mill. Quick frontal sliding To speed up the process in total safety, Fives has developed the ETF frontal quick-change system. The ETF system is designed for the automatic frontal replacement of the tooling cartridges by sliding them in and out over the carriages running on rails. Driven stands, idle side passes and the welding box are all equipped with removable cartridges that can slide off the mill frontally, to be loaded to and unloaded by robust carriages running on rails. As a distinctive feature, both the lower and upper shaft can be lifted at once, and the first breakdown

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MARCH 2022

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