Re: Combined Convex Concave Curves At Trippers
Hello Gareth..
I was called in to consult on some tripper conveyors where the belts were failing despite a reasonable safety factor.
The reasons for failure were:
- Cord damage due to loading impact being greater than 1000 Joules
- Coastal environment corroding cords
- Winch take-up response time too slow
- Material getting locked into the pulleys
- Unsupported length of belt into the tripper too long.
The last one caused alot of the grief, as in troughed formation combined with the sag over the long span caused the edge tension to dissapear. The conveyor was nearly 2km long to the tensions were high, and these tensions were being taken only by the middle third of the belt.
I did my own calculations based on the stress distribution across the belt using the known belt modulus. This was not that difficult, and showed very clearly why the belt failed down its middle, especially at the splices.
I generally however use the Goodyear simple formulae for vertical curves
Regards
LSL Tekpro ■
Re: Combined Convex Concave Curves At Trippers
Dear Gareth,
I believe we have the Oehmen papers related to the strain field in steel cord belts in their idler transitions and horizontal curves.
The University of Hanover will have the library on this since father and son did their research there. I cannot remember if it was the son who did the work, which goes back 15-20 years or more.
This is again archived. I think Fluor did the German to English translation. Unfortunately, I think we found a flaw in Oehmen's reasoning when we made a study of the subject. I know its bad form to make comments that do not have the facts to back up the accusation. If I find the work in the near future, I can lend more light on it.
I know I still owe you for the pulley stress work. I am trying to prepare for a overseas trip and wish to keep my clients content (sic?). ■
Re: Combined Convex Concave Curves At Trippers
I also note that you are digging into a lot of technical detail on a variety of sugjects germain to belt conveyor technology.
Are you not a now or gonna be competitor of CDI? ■
Re: Combined Convex Concave Curves At Trippers
Larry,
I have no desire to delve into the mathematical complexities of conveyor design as you have.
We are a consulting company doing the general run of the mill projects for industry.
However we have a desire to bring our clients the best possible designs with current industry understanding. It has been my experience that this is not commonly done.
There is a lot of good design information out there that is not being utilized.
In summary I believe you are looking at taking design to the next level. I simply wish to use the best of that which is already known. So no we will not be in competition with CDI except for the hope that you will not have to be called to fix any stuff ups at any of our plants.
You visit Australia much?
Best Regards,
Gareth Blakey
blakeyg@conwag.com ■
Re: Combined Convex Concave Curves At Trippers
Delving into Oehmen's, Lange's, or Schmoltzi's work is on a Ph D level. Maybe, they train'em young in Oz.
We know who you are and many of your offices with whom we do business. We have the same goals.
Ahmen to the utilization of good information.
My level on interest is to observe a quiet lake, tumbling water or crashing waves. Conveyors are now secondary. However, if you embark on knowing the technicalities illustrated and beyond, it sounds ominous for CDI.
I thought you would'nt ask. By phone every day. By person about 4-6 times per year.
Sydney, Brisbane, Perth, Melbourne, and the outback
Koniambo
Curragh
North Parks
Cadia
Yandi
Channar; upgrades; Eastern range
Muja/Collie
German Creek
BHP Bi-way and under the sea
Gove
and many more. ■
Re: Combined Convex Concave Curves At Trippers
Don't suppose you know the title of the Oehem's paper. German or English will do.
Feel free to give me a call when you are in Perth or Brisbane next.
My contacts are on emails I have sent direct to your CDI email address.
By the way does more than one person use your login to this forum?
Best Regards,
Gareth Blakey
blakeyg@conwag.com ■
Re: Combined Convex Concave Curves At Trippers
The title is:
"Calculation of Strain Distribution in Belt Convyors by Troughing Transition, Belt Turnovers and Cord Disconnection (splices)"
Author: Dr. Klaus Heiner Oehmen, Hannover University
Published in Braunkohle (12) 394-402, 1979
It translates to 30 pages in English.
Carrot?? ■
Re: Combined Convex Concave Curves At Trippers
Gareth,
1. I am still trying to locate the Lange papers.
2. I am curious about your multi-person login in question -can you explain?
3. I sometimes uses my wifes computer at home at night - handle snordell ■
Combined Convex Concave Curves at Trippers
Hello all,
Firstly this post is referring to the combination of concave and convex curve at the tripper entry point. The purpose of the curve combination is to reduce the effects of edge tension deviations the curves.
I am aware of David Beckleys work but have come across some German equations on the subject.
Has anyone heard of the OEHMEN equations or is anyone aware of any other papers that have been written on this topic.
Best Regards,
Gareth Blakey
blakeyg@conwag.com ■