In Spring 2015, American Cement Company asked Kobo USA for help with its limestone reclaimer system.
Following a survey of the limestone reclaimer being used by the company, it was discovered that large size rocks in the limestone pile that had come from the crusher were causing increased wear and failure of the chains and shovels. As the shovels came into contact with there 10 – 12 cm rocks, shock loads were causing damage to the chain system, with the bushes of the chains having cracked and the shovels breaking at the seams of the welded chain attachments.The chain system, which was made up of attachment plates welded to one link plate of the chain clearly needed to be improved, in order to allow it to last in these difficult conditions.
Kobo USA analysed the existing chain at its in-house laboratory, before reporting its findings to the customer: the breaks were being caused by high peak loads that was making the material bend before it cracked.
Kobo USA worked with American Cement to create an improved design for the chain. This new design retained the majority of the dimensions, but increased the bushing size in order to strengthen the chain against dynamic shock loads. The sequence of attachment was also altered from every third link to every second link, meaning that each individual shovel was responsible for dragging a smaller amount of material. By welding the attachment on both sides to the inner link plates, Kobo USA was able to stiffen the construction of the attachments., while the inclusion of a thicker stiffening prevented larger rocks from damaging the shovels. Replaceable scraper wear bars were attached to the sides of the shovels and could be easily replaced by loosening two bolts. Finally, Kobo USA provided new tooth rims, as those already in place were worn.
Weight and working load calculations indicated that the existing motor and gearbox would be able to handle the new chain without modification, and the new design was approved by the customer.
Adapted from press release by Rebecca Bowden
Read the article online at: https://www.worldcement.com/the-americas/15092016/kobo-usa-help-american-cement-company-269/
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