Plate Development

[Scary99]

I am laying out a sloping bottom in a large diameter tank.  It is unlike any I have seen before.  This will be constructed of stainless steel so an accurate layout is important for purchase of materials.  I have attached a file that shows the dimensions required to achieve the bottom as it will be constructed.  I am at a loss for a flat plate and forming sketch.  Suggestions?

[TheCADnoob]

I might check with the folks over in the Plant 3D area and see if they have any ideas

https://forums.autodesk.com/t5/autocad-plant-3d-forum/bd-p/371

[john.vellek]

Hi @Scary99,

I am not sure I understand the drawing you provided.  ON the plan view is the part at the bottom a baffle? or, is that where the slope  changes for the floor?

In the section, does the long  slope run past the center point? For example does it run all the way from one side of the tank to the other?  What is the short steeper slope meant to indicate?

I am happy to help if I have a better idea of what you are trying to accomplish.  I don't think Plant 3D is designed to create a tank so with further detail I might be able to suggest a different application if AutoCAD is not suitable.

Please select the Accept as Solution button if my post solves your issue or answers your question.

[SEANT61]

Is this the general notion?

[Scary99]

Thanks for your reply John . . . The plan view shows the flat tank bottom as 46'-3 diameter and the tank shell as 46'.  The false bottom begins at a single point 23' above the flat bottom and then slopes away from that point in two directions along the shell until it meets the flat bottom at points 14' on either side of the tank centerline.  The sloping bottom is actually a eccentric cone with dimensions of 46' diameter x 60' diameter that is cut with a plane perpendicular to the vertical axis at the 60' diameter end and cut with a sloping plane at the 46' diameter end.  The cut on the plates attached to the shell is a parabolic curve.  I can layout these out and project just as done with sheet metal drawings but I am hoping that Autocad can take the overall dimensions and develop the plates.
Thanks againLarry

[john.vellek]

Hi @Scary99,

I am trying to figure out the eccentric cone portion of this issue.  Drawing the cylinder by using two circles and a presspull is very quick. Finding a point on the cylinder at a height of 23' is also easy.

Figuring out the cone is different as i do not know the height of the cone, if there is an offset between the two radii, etc.

Can you give me a bit more information? I am sure all of this can be done in AUtoCAD although Fusion 360 might be a better application.

Please select the Accept as Solution button if my post solves your issue or answers your question.

[beyoungjr]

I worked on this a while today and cannot come up with anything that seems like what you describe.  Your description is a bit all-over-the-place for me but I'm quite sure it all makes sense at your end.

Breaking it down...

The plan view shows the flat tank bottom as 46'-3 diameter and the tank shell as 46'.

---

Neither of the radii labeled on your drawing match these numbers so where are these with respect to your dwg details?

@john.vellek asks the same I would ask... define the cone better or the contours that will develop the funnel-like bottom.  At this point even a hand sketch with some labeling could possibly help.

The image below shows a 60' curve that I tried to loft from the 46' curve but did not look anything like what would be needed.  The loft I did show is from the 46' curve to your contour lines on the tank bottom at a 23' height.  Still don't think this is what you want but somehow we need to get better comms going.

Cheers,

Blaine

[Scary99]

Thanks again for your input John.  I did describe the bottom in a confusing matter and I apologize.  I sometimes assume everyone is a "tank" person and understands what we design and build.  I have drawn a simple plan with a section cut thru the center line.  Note we did away with the smaller radii in the corners near the center of the tank as the operators said forming the plates will be much simpler if we have a single constant radius at the smaller ends of the plates. This bottom will be constructed from 3/4" stainless steel so forming will not be an easy task and it must be nearly exact. I also put a dimension in the plan showing the offset of the 23' radius and 14' radius.  We typically draw to scale and project to develop the curved cuts at the ends of the plates but I think there must be a better way than the way we did 25 years ago.  Thanks again.  Hope this clarifies somewhat this odd creature.

[Scary99]

Thanks for your input and work on this for me.  Looking at your 3-D sketch you are almost there.  We did simplify the bottom end somewhat by eliminating the 2 small radii and using a single 14' radius.  For reference purposes we will call the open end 180 degrees.  Start at the 23' elevation at 0 degrees and slope the curve down and along the 46' diameter cylinder until you reach the flat bottom.  That point of intersection will be 14' on either side of the 0 - 180 degree center line.  As you already know we are creating an eccentric cone (46' diameter on one end and 28' on the other) and then cutting with a sloping plane at the 23' elevation and a plane perpendicular to the vertical axis at 0' elevation (the flat bottom).  Hope this clarifies somewhat.  A simple plan and section is attached.

[beyoungjr · Accepted solution]

Hi again,

I still have trouble developing an eccentric cone with only 2 diameters but I think I have managed to develop the solids for your project (see attached dwg).  Instead of developing a cone I simply lofted a surface using the contours dictated by your front and top views.  I then thickened the lofted surface, subtracted it, separated the solids, and erased the upper to reveal the sloped solid.  Since this is a false bottom you could simply thicken the lofted surface  and place it inside of a tank (also shown, all having a 1" thickness).

Please have a look and let me know if this is the correct design.  If so I'll provide more info on steps taken, or maybe a screencast.

Just remember that AutoCAD will not automate your plate divisions without an addon of some sort.  Inventor and Fusion will do sheet metal work.

Cheers,

Blaine

[Scary99]

You have it.  The isometric that is farther to the right where the 14' radius is on a plane perpendicular to the vertical axis is actually how this thing will look when it is built.  Will it be possible to extract dimensions from individual gores?  The size will require a layout of 19 plates total.  One that straddles the center line at the high point and 9 on either side continuing to the flat bottom.

[leeminardi]

I created an eccentric cone with 14' and 23' radii, added an extrusion to the right and did a Boolean union and got the result shown below. Although the bottom view of my tank is the same I am obviously missing something!  My slope is nothing like the line you show for the sloping conical bottom.  Your drawing shows the full diameter of the tank coming all the way to the ground.  Should this be? Should the two circles that define the cone not be parallel to the ground?

[beyoungjr]

You would certainly be able to extract dimensions once you divide it into gores (segments).

I can create a lattice of surfaces to segment the shape.  The easy part is the meddle plates straddling the centerline.  The remaining plates would need to be segmented by a determined angle of projection.  This is the hard part  that a sheet metal or structural steel pattern software would accomplish.

If you can define the angles to project and segment the object then it can be done "old-school" in ACAD.  Oh yeah, max size of target plates as well.

Blaine

[schulz8NPAP]

...and the flattened layout should be as attached.

Regards

Jochen

www.ant-ares.de

[Anonymous]

Did you use AutoCAD to unfold/unwrap this?

It is a polyline but when exploded it is individual line segments.

You got it flat so you should be able to divide it up into the segments you wish.  Not sure how you wanted it divided other than the quantity of pieces.

Blaine

[Anonymous]

Is this what you need?  180 degrees divided by 19 = ~9.47 degrees per segment, middle divided equally to span centerline.

[beyoungjr]

Something messed up with my 2 Autodesk accounts...

If you find that I solved anything please mark it solved for the @beyoungjr posts.

Thanks,

Blaine

[Scary99]

You have the correct radii and the structure is a bit confusing.  Imagine this eccentric cone with 46' diameter at the top and 28' at the bottom.  Cut across the bottom creating a 28' diameter opening with a plane perpendicular to the vertical axis.  Cut the 46' diameter cylinder with a sloping plane that will intersect the flat tank bottom at the points shown in the plan view (a horseshoe opening 28' wide).  The resulting plate edge that contacts the tank shell would be a portion of an ellipse (cylinder cut on a sloping plane).  The accepted solution does show a 3-D cad rendering of the structure.

[Scary99]

I looked over the 3-D cad you sent and it captures the structure.  We do use "old school" autocad to project and measure the lines.  We hold the large end of the plates less than 8'-0 since it is readily available and minimizes welding.  We measure points appx 1'-0 apart and determine the radial lengths to approximate a developed cut on each end of the plate.  We then press the plates using the finished height and horizontal radius for each plate.  Time consuming for the shop since we have 9 different plates to layout and press.  Appreciate everyone's efforts very much.  The solid you sent came in handy as the paper mill is considering filling the void behind the slope with grout and asked if we could give them the volume.  It was right there on the drawing  . . . . 333 cubic yards!

[schulz8NPAP]

Yes, it's AutoCAD and an application from www.ant-ares

Regards

Jochen