How to calculate the flat form of a flight of screw conveyor
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Posted by: Pat_Couture ® 03/01/2004, 13:20:29 Author Profile eMail author Edit

Hi, I am trying to calculate the flat form of a flight for a screw conveyor, and the formula I use is not accurate and it's driving me crazy, so is there anyone who has a clue on this. Thanks in advance. Patrick

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: How to calculate the flat form of a flight of screw conveyor
: How to calculate the flat form of a flight of screw conveyor -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: santoshsalvi ® 06/09/2009, 01:24:41 Author Profile eMail author Edit

Can someone help me understand if it is possible to use a screw conveyor instead of a slurry pump to discharge material to a distance of 20m. Our company has a screw conveyor of 1.5m long of size 12" and material is caustic sludge. thanks

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: How to calculate the flat form of a flight of screw conveyor
: How to calculate the flat form of a flight of screw conveyor -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: rvr3 ® 12/05/2008, 11:04:48 Author Profile eMail author Edit

I know of no fromula. However I have a proceedure for developing the layout in the flat if you are still interested. Contact me at Atlantic Metal Producte, Topping, Va. Ray R.

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: How to calculate the flat form of a flight of screw conveyor
: How to calculate the flat form of a flight of screw conveyor -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: rvr3 ® 12/05/2008, 11:02:48 Author Profile eMail author Edit

I know of no fromula. However I have a proceedure for developing the layout in the flat if you are still interested. Contact me at Atlantic Metal Producte, Topping, Va. Ray R.

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Re: How to calculate the flat form of a flight of screw conveyor
: How to calculate the flat form of a flight of screw conveyor -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: HAG ® 12/16/2006, 06:14:35 Author Profile eMail author Edit

Hello all, Perhaps perchasing helicoid flighting for standard size screws may save you some time. Flighting is avalible in 6",9",10",12"14",16" dia. in full, half, and 2/3 pitch to fit std. pipes. 304SS and mild steel are readily avalible at low prices. Most come in 10'-0" lengths. Slide flight coil over pipe and tack weld one end. Stretch from other end with a come along or hyd. cyl. and chain. Weld to pipe as needed. If you are looking setup to manufacture screws, you will need a flight press. Most are single hit using a set of pie shaped dies to form the sectional flights. The formulas listed in other replies will give you the blank size "on paper", but the reality of making flightings is lots of trials. Variables such as mild steel vers. antiabrasive vers. stainless steel will change flight pitch as much as 1". Wear on the die head and press setings also play a part. On a new flight size I always run (2) trial blanks across the cutting table using std. formula to find O.D. I.D. After cleaning slag and rust from blanks, have each formed to slip fit over pipe. The press operator measures the pitch and O.D. on both. This info. is returned to production. If the pitch and O.D. are within CEMA spec., record the info. and burn out as needed for the job. If they do not pitch out correct, increase or decrease the I.D. and O.D. If you just need a few flight and want to make them just to make them, "OLD SCHOOL" way,not so long after ARCHIMEDES wood screws, black smiths would take a disk and heat it red to yellow hot. Hold one end with hammering tongs, hang the other end over anvil edge and hammer out flights. Sounds like too much work for me. Falcon Company also sells std. and special size rolled helicoid flighting. I will Email an Excell Sheet I use to calc. blank sizes if you want a copy. Modified by Administrator at Sat, Dec 16, 2006, 08:01:28

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: Re: How to calculate the flat form of a flight of screw conveyor
: Re: How to calculate the flat form of a flight of screw conveyor -- HAG	Post Reply	Top of thread	Engineering Forum

Posted by: troy bodle ® 01/22/2009, 13:52:29 Author Profile eMail author Edit

I have been working this same problem and have come up with what looks kile a pretty easy solution. I take the diameter of the center shaft, 1/2 the pitch and find the hyp length. then devide the hyp by 1.13. This will get you extreamly close. you can then multiply the desired diameter by the same (1.13) and you will have a concentric ring that should expand to meet your needs. I just built a couple using this formula and it worked great If this seemes clear as mud, just email me and I will send you a diagram of the procedure with a better layout. Troy

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Re: How to calculate the flat form of a flight of screw conveyor
: How to calculate the flat form of a flight of screw conveyor -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: srmujawar ® 06/12/2006, 02:37:06 Author Profile eMail author Edit

Can anyone tell me the sourses to Design Drag Chain Conveyor

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Re: How to calculate the flat form of a flight of screw conveyor
: How to calculate the flat form of a flight of screw conveyor -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: fcwb0458 ® 03/27/2006, 16:31:38 Author Profile eMail author Edit

You have D (outside flight diameter), d (inside flight diameter), P (pitch of flight). So consider that b is the result of (D-d)/2. Now developed the outside diameter, A = square root of [(PI*D)^2+(P)^2]. Then the inside developed diamater, B = square root of [(PI*d)^2+(P)^2]. - Value of PI = 3,1415926... So the developed inside radius of the flight will be: r = R-b => b=R-r; b/r=(r-R)/R - 1º step R/r=A/B; (R-r)/r= (A-B)/B - 2º step consider that R is the developed outise radius. so we have: b/r=(A-B)/B then... r=(B*b)/(A-B) that is valid for cylindrical screw flights made with plates. enjoy

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using Pro/E
: How to calculate the flat form of a flight of screw conveyor -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: imitea ® 03/04/2004, 13:15:24 Author Profile eMail author Edit

Hi, Give me the exact shape what you want to have (ID, OD and pitch).I will provide you a drawing with the flat form Bye Julian Modified by imitea at Thu, Mar 04, 2004, 13:16:03

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Re: using Pro/E
: using Pro/E -- imitea	Post Reply	Top of thread	Engineering Forum

Posted by: Pat_Couture ® 03/04/2004, 14:07:17 Author Profile eMail author Edit

Hi, Are you telling me that Pro/E can flatten this type of shape? It's a screw of 9" OD, 9" pitch and a tube of 2"1/2 sch 40. (2.875) inside of it. Thank you Patrick

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Re: using Pro/E
: Re: using Pro/E -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: vipulred ® 04/18/2005, 08:04:58 Author Profile eMail author Edit

Dear Partik, I also want to know the formula or calculaion of screw flight cutting i.e. OD & ID. Can you explain me or send me calculation. If possible I want to make Screw of following. 1. Diameter 312mm 2. Pitch 321 mm 3. Pipe Outer Diamter is 73mm Can you give me the exact side to cut ID & OD of screw flight. Awaiting your reply soon. Vipul M. Panchal

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Re: using Pro/E
: Re: using Pro/E -- vipulred	Post Reply	Top of thread	Engineering Forum

Posted by: RAJESH GAUTAM ® 08/16/2005, 05:26:51 Author Profile eMail author Edit

Dear Sir, I want formula and calculaion of screw flight cutting drawing. please you explain and send calculation. I want to make Screw of following. 1. Diameter 1980 mm 2. Pitch 4500 mm 3. Pipe Outer Diamter is 3000 mm give me the exact size of screw flight. Awaiting your reply soon. Rajesh Gautam

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Re: using CAD
: Re: using Pro/E -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: Cragyon ® 03/04/2004, 15:09:48 Author Profile eMail author Edit

Not to get into a tic-for-tat but, Solid Edge by Unigraphics can do it as well. Modified by Cragyon at Thu, Mar 04, 2004, 15:11:00

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Re: How to calculate the flat form of a flight of screw conveyor
: How to calculate the flat form of a flight of screw conveyor -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: RandyKimball ® 03/01/2004, 19:41:29 Author Profile eMail author Edit

Are you talking about the spiral that runs around a shaft on a screw conveyor as used for grain elevators? If so this has to be done in sections or milled in a rolling mill that coins the outside diameter edge thinner than the inside radius thus causing the coil sheet to spiral as it leaves the mill. There is no flat-out for that. -randy- The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.

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Re: How to calculate the flat form of a flight of screw conveyor
: Re: How to calculate the flat form of a flight of screw conveyor -- RandyKimball	Post Reply	Top of thread	Engineering Forum

Posted by: Pat_Couture ® 03/02/2004, 07:37:13 Author Profile eMail author Edit

Hi Randy, yeah it's exactly what I'm talking about, as you said we can do it in section, for example my screw conveyor has a 9" outside diameter around a tube of 2 1/2 sch 40 with a 9" pitch, we use to cut many item of a circular shape (who looks like a donut) of approximately one pitch each in a sheet metal then we weld them together after that, we stretch it with the tube inside until the inside is near enough of the tube. The problem that I have is that I have to do 3 to 4 test of different dimension before I can find the exact radius for my donut to give me the pitch I desire. That's why I would like to know if anybody can give me a clue about this. Thanks Patrick

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Re: steel drum1
: Re: How to calculate the flat form of a flight of screw conveyor -- Pat_Couture	Post Reply	Top of thread	Engineering Forum

Posted by: RandyKimball ® 03/02/2004, 20:18:30 Author Profile eMail author Edit

Patrick, Sometimes the quickest and most effective engineering is what I call reverse engineering, one of the best reverse engineering tricks I know is the good old cardboard and pocket knife method. You can evolve through several pieces of cardboard shapes quickly and cheaply to effectivly devise a shape to fit most any situation. In this case I'm thinking by developing a few different configurations in this method you will soon spot the pattern and likely the best formula. You can then either share the formula or keep it as an in-house knowledge base. I often use this method to develop an adaptor such as for hydraulic clutch linkages on street rods. After the adaptor is developed in cardboard it is a simple matter to transfer it to CAD for future reference or manufacturing. -good luck- The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them. Modified by RandyKimball at Tue, Mar 02, 2004, 20:26:08

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Geometry also help
: Re: steel drum1 -- RandyKimball	Post Reply	Top of thread	Engineering Forum

Posted by: devitg ® 04/10/2004, 17:51:39 Author Profile eMail author Edit

That screw is called a auger , it is also named the ARCHIMEDES SCREW. It's easy to calc by simple geometry. First step = get the pipe perimeter 2.875 * pi = 8.7493281 " Think you develope the pipe surface in plain after you mark where the fligth meets the pipe. So you will have a  rectangular triangle whose sides are the pitch = 9" and the developed perimeter =  2.875 * pi = 8.7493281 " and it's hypotenuse is Ih = Square root ( 9^2 + 8.7493281^2)= 12.55192704 This measure is the depeloved perimeter of the internal  diameter of the "washer" so Ih/pi = ID in this case is 3.995402467 By the same method you can get the outside diameter the 9 in OD is 28.27433388 the pitch is the same 9 so the OH =29.67217479 and the OD is =9.444946579 so you need to cut a "washer" 9.445" OD and  3.99" cut it and weld one after one and then strech it over the pipe You can know all about arithmetic , but you will not know enough geometry.

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: Geometry also help
: Geometry also help -- devitg	Post Reply	Top of thread	Engineering Forum

Posted by: KBolt ® 07/04/2008, 16:21:28 Author Profile eMail author Edit

...did anyone of you know that you are wrong ? None of the CAD- / whatever software can draw the flat shape CORRECTLY. You might look thru descriptive geometry books and find out that the blade of the conveyor screw is little different case compared to others. It is almost impossible to calculate the inner diameter accurately. It is usually done by using the pythagoras triangle but that does not give the right answer. And why is it hard to calculate ? One thing is that no-one makes blades that are 0.1mm thin. If the blades could be that thin then it would be easy to calculate right values. All those calculations above gives the screw line where the blade should go. Well...the blade goes according to the screw line if the blade is extremeley thin.... The other problem is that the shape of the blade (especially the inner diameter) is A POINT MOVING IN 3D SPACE. You can not flatten that kind of shape... The only way to get the exact inner diameter (and based on that the outer...) is to make one blade by fitting it manually. Some say the flat shape of the blade can be drawn by CAD or some 3D modelling software...well, sure. Only problem is that it's bulls***.

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: : Geometry also help
: : Geometry also help -- KBolt	Post Reply	Top of thread	Engineering Forum

Posted by: labargep ® 06/04/2009, 16:44:48 Author Profile eMail author Edit

Try using the sweep command in AutoCad. The help file will explain it. It allows you to create a 3D object following a path such as a helical polyline. I've used it for thread layouts with good results. (You can also find good tutorials online by searching "drawing 3D threads"). once you have the 3D flight drawn, "EXPLODE" or "BURST" it and perform a "LIST" command on the inner and outer diameter polylines for (1) revolution. This will give you a good reference point for material layout. Otherwise you could just draw the inner and outer helix's using the "HELIX" command and measure them if you don't need to draw the 3D model for the project.

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