Chain conveyor thru a heater.. Holding tension

[EspElement]

Hello guys, I am new to this forum and I am currently working on my engineering degree.. I work as a designer now for a palletizing company.. i have a very unique application that i would like to share with some others and get their thoughts

A company that is very close to our facility is buying a chain conveyor that is running thru a heater.. They produce chemicals.. and they send barrals of them into the heater to liquify them.. They currently run gravity conveyor thru it and they a stick to push and pull them thru.. They would like a powered application and due to our limited space, cant use live driven roller.. We offered using chain conveyor for the application.. Heres what i am doing

Using double 100 pitch chain.. 2 driven chains.. barrals 550 lbs each.. up to 9 on it at a time.. They would like to run the conveyor in forward and reverse.. so a center driven application is required.. Conveyors are about 12' long.. temp gets up to 200 degrees F.. I am able to drive the conveyor outside of the heater on the tail end of the normal running direction.. my solution is to use 2 custom chain tensioners with 2 different springs.. one taking up about 200 lb of load (tsubaki recommends only using 150 lb max of tension on the chain without prematurely stretching it.. they claimed we could use a little more, due to high safty factors.. im not sure where they get this when i calculate the working load to be 5000lb per chain) and the 2nd spring take up about 500 lb of load.. (due to the coefficent of friction on the 550 lb pails, my max load is 1980 lb(550*9*.4), so about 1000 lb on each chain) since i am pulling down on the tightener 90 degrees, i figure the tightener will take half and the mount for the tightener will take half

i would wrap the chain 90 degrees on each idler sprocket that is attached to the tensioner.. below it a 180 degree wrap on the drive.. the tensioners will push in toward each other over the driven section.. I invision when the chain is ran forward the leading tensioner will compress its 200lb load, and as its pulling the larger load, compress into the 500lb spring (if chain has expanded, spring will take up the difference).. on the tail end, it will work in reverse, as the chain will become loose it will pull it tight against the drive.. so no matter what direction i run, or how much the chain expands.. it will stay tight on the drive.. what would your guys opinion on this application be?

I appreciate anyone who is interested in reading my issue.. just want to get another oppinion on my situation.. i plan on getting involved in these forums to help me learn more about fellow engineers applications

thanks again!

 

[dvd]

My additional 2 cents:

1. Don't forget that this is a reversing conveyor application. The tight side on loading is the slack side on unloading.

2. Tension in the chain isn't everything. You may have someone slamming barrels down on top of the chain links. I don't think that RC100 chain is overbuilt for this application.

3. Is this double strand 100-2

http://ustsubaki.com/pdf/gen_catalog/gen_a13-a19.pdf

or double-pitch 2100 chain

http://chain-guide.com/applications/2-1-2-double-pitch-roller-chain.html

4. Nine 55 gallon drums at 22.5 inch diameter equals 16'-10.5"

5. Even if the sprockets are very closely timed one side will momentarily bear all of the load.

 

[EspElement]

Dvd
Yes you are right, this weekend i was thinking the conveyors were somewhere around 12' that is the amount inside the heater.. they can put 6 in at a time.. and station 3 outside.. very good observation

It is 100-2 sorry for the discrepency

With my intial thoughts that is how i anticipated the tighetners to function.. leading side bears it, tail end of the drive takes up the slack.. It doesnt sound like the stratch will be much as we found out.. my coworker moved forward with our initial designs over the weekend and i shared some of the things we discussed here.. i will also bring up the thermal expansion calc tomorrow to him and discuss our thoughts.. we are just about done just putting finishing touches, i suppose at the minimum the tensioners will allow us to be sure the system runs smooth.. the big problem with this at work is they want 7 of these conveyors.. so everything that is done is times 7.. if we have any issues the costs will skyrocket quickly.. in addition, if we could save the tensioners,.. the savings would skyrocket as well

Also, we are using and N6 with needle bearings in the idler spockets.. we are not using a keyed shaft for any of the sprockets but the drive.. everything else is independant

thanks again

 

[dvd]

Well good luck with everything. You will obviously gain some new knowledge.

 

[unclesyd]

Have you looked at these type metal belts?

http://www.meshbelt.com/Chainweave.html

 

[tomwalz]

Not sure why you need a chain under tension. All you want to do is move the barrels slowly through a 200 degree oven.

We braze at about 1500 F, use flights and just run the dive train belt down a track with a pulley on each end.

I have seen food service operations do something similar with carts.


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[unclesyd]

tomwalz,

Your specifics are exactly the reason for my previous post as these type belts don't normally require a tensioning device and tension may actually create problems.

 

[EspElement]

Tom,
typically you wouldnt have to put tension on chain but because im moving in forward and in reverse.. it needs to be tight enough to pull the chain from both direction

Actually your application of 1500 F is a good example that is beyond typical temps.. i did some looking that 400C (750 F) is getting to the line of standard ANSI roller chain.. Sounds like you are using something like uncle recommended, that chain reminds me of that mesh kind of chain we use

http://www.beltpower.com/FlatWire.htm

it appears they make that roller chain belt stuff as well

that stuff isnt cheap.. we pay 2 grand or so for a 10 foot conveyor

 

[tomwalz]

He’s probably not really perfect but unclesyd seems to nail it about 100% of the time.

I got a quote from Audubon (

http://www.meshbelt.com).

They are fast. Sent the info in last night and the quote was waiting for me this morning.

This is what I sent them:
Overall Belt width – 6” flights
Belt length 25 feet
Distance from drive axle to idler axle is 11 feet.
Hot zone is 45” long
The parts go from ambient to app. 1500F if 45” which takes about 4 to 4 ½ minutes
The belt moves about one foot in one minute to 70 seconds. (Speed is variable)
The drive is on the charge end
The drive is hardened steel chain.
The chin is supported on skids the entire length.
The drive pulley and tail pulley are 10” in diameter and toothed.
The maximum load per square foot is well under one pound.
The product being conveyed is saw tips. The minimum size is 0.250” x 0.100”.
The maximum temperature is 2200F
Normal operating temperature is about 1900F
The belt is horizontal.

We need to replace the flights every year or two depending on use. After several replacements the holes in the drive chain are now oversize allowing some shifting of the flights.

I would like flights that will hold up better.

This is their quote.
Item: 6" Wide X 25' Long
Type: Balance Weave
Wire: .063" Dia
Edge: Welded
Metal: 3519 Cb
Spec: B-48-47-14
Price: 25 Linear Feet @ $45.40/Lf $1,135.00

Price looks o.k. I pay about $500 for a set of new flights plus the cost of attaching them the chain.

Not sure about switching from flights to mesh belt with parts as small as 0.100 x 0.250 when the parts have to be kept level.

Tom


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.