
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.
On a new flight size I always run (2) trial blanks across the cutting table using std. formula to find O.D. I.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.
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.

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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 (Dd)/2. Now developed the outside diameter,
So the developed inside radius of the flight will be: r = Rb => b=Rr; b/r=(rR)/R  1º step R/r=A/B; (Rr)/r= (AB)/B  2º step consider that R is the developed outise radius. so we have: b/r=(AB)/B then... r=(B*b)/(AB) 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.
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.
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 ticfortat 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 flatout 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 inhouse 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. First step = get the pipe perimeter 2.875 * pi = 8.7493281 " So you will have a rectangular triangle whose sides are the pitch = 9" and the developed perimeter = 2.875 * pi = 8.7493281 " This measure is the depeloved perimeter of the internal diameter of the "washer" so Ih/pi = ID so you need to cut a "washer" 9.445" OD and 3.99" 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 ?
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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