Rectangular Duct Flange Configuration

[trekfan]

Good morning to everybody. I have a question about configurations. I am trying to build a rectangular flat duct flange to weld onto the end of a piece of HVAC ducting. My customer specs that I must pre hole the flange for him, and the max centerline distance between holes cannot exceed 2". The holes must be evenly spaced along the edges. What I cannot remember how to do, if it is even possible, is to create a rule, that if the spacing is larger than the 2" it adds another hole to compensate. I will be build a large number of these in many many numerous sizes, and was hoping to use a Excel based design table to handle the sizes. I can email a model if anyone wants to see. I am currently using Solid Works 2007. I have uploaded a model of what I am attempting. I have the basic design with the center holes on the "X" and "Y" axis, but now need to pattern the rest.

Thanks,
Rob

 

[handleman]

I would probably go with a couple of equations outside of the design table because equations update with every rebuild.

You would need two equations. The first calculates the number of holes based on the length that has to be filled. This would be 1 plus the length divided by max spacing rounded up to the nearest integer. The second equation is gives the spacing, and it is the length divided by 1 less than the number of holes calculated in the first equation.

-handleman, CSWP (The new, easy test)

 

[handleman]

I'd make an example, but I only have 08 and 09.

-handleman, CSWP (The new, easy test)

 

[smcadman]

I don't have time right now to look at your file, but someone had a somewhat similar problem and there was some solutions that you would be able to use.

The samples are in SW08, but I pasted the equations used on the parts so maybe you can follow the logic behind them. Basically it used If statements with a Like thrown in for good measure.

http://www.eng-tips.com/viewthread.cfm?qid=225559&page=13

Flores

 

[handleman]

From your post, it sounds like you really don't want to use IIF statements. There would just be way too many of them.

-handleman, CSWP (The new, easy test)

 

[handleman]

Here is a picture of how to set this up. It's similar, but a little bit different from what you want. It's all just math, though. The design intent of this one is that there are some number of holes evenly spaced such that the first and last one are always 20mm ("Inset" dimension) from the edge of the part. I defined a global variable for the maximum pitch of 60 ("MaxPitch"). The only part that's a bit more than basic math is the int() function. Its purpose is to always round up if there is any remainder. The int() function always rounds down in value. This means that both int(3.8) and int(3.2) are 3, but int(-3.2) and int(-3.8) are both -4. So I used -int(-(value)) to always round up.

-handleman, CSWP (The new, easy test)

 

[CorBlimeyLimey]

Take a look at the Fill Pattern function. It will do what you want without the need for equations.

 

[trekfan]

Thank you so very much for the rapid replies. I have made quite a bit of progress and am uploading my model that I have built so far. I have run into 1 small snag. The center piece on the assembly is just to show duct open size, and the side flanges are modled to it. I followed the steps from the previous posts and have made the holes re space and work correctly. My goals are to build a Excel design table around the center part and have it build the many (1000+) configurations of flanges. But if I update the size in the assembly and rebuild, the flanges will correct themselves properly, but the holes and spacing will not update unless I go to the parts themselves. Am I doing something wrong, or have I chosen the wrong path to go down?

Thanks,
Rob

 

[trekfan]

New PostCorBlimeyLimey (Mechanical)
27 Feb 09 11:34
Take a look at the Fill Pattern function. It will do what you want without the need for equations.


I tried the fill pattern, but it did not seem to do the trick.

 

[trekfan]

In the assembly model I previously posted, is it possible to make a design table in the assembly and drive the parts from that? I have been trying (unsuccessfully) to make changes in the assembly to the center duct plate, and have it redraw the flanges. What is basically happening is the flange lengths will update but the hole patterns will not update. Is there perhaps somethig I am missing to make this work, or should I abandon hope and regroup another direction?