Stretching to work with sheet sizes?

[Phil Greer]

Hi all, this may be a simple question for some, so here it goes:


I want to knowhow best to usea relationship (or any other means, really) to change the dimensions of a sheet but keep the TOTAL size of the sheet the same.

Ourmetal sheetcomes in standard widths of 1200, and weuse the whole sheet neatly, so the width of the back is dictated by 1200 minus the switchboard depth+front fold+seam fold.


Can an'anti-equal'relationship be made between the side and the back, so that for every mm of depth is increased the width of the back is decreased accordingly?









Edited by: Phil Greer

 

[Mihail]

First way is to use EQUATIONS, where a dimension is calculated from the others. It is simple to do that and simple to understand. Look in SW help for using EQUATIONS.

The second way is to draw 4 (in your case) collinear lines. Start point of line 2 is the end point of line 1 and so on. Dimension all chain (1200). Dimension first line (100), the second one (650) and the last one (20). Of course, the third line will be 430. (You can also dimension this line but be sure that this dimension is DRIVEN (right click on the dimension and make the setting).
The last step is to establish the relations between the new created chain (4 lines) and your sketch (4 lines too) (the relations will be EQUAL).

Now you can play with the dimension in the "chain" and SW will modify the sketch for the bending sheet.

BE CAREFUL !
100 + 650 + 430 + 20 = 1200
but, to obtain this dimensions, the length for unfolded sheet
IS NOT 1200

Good luck !




Edited by: Mihail

 

[Phil Greer]

Thanks for the response! While on the topic of stretching in sheetmetal, I have another related question for anyone who knows the answer -


I want to know how we can set an assembly up so that when you stretch the two sides apart it will automatically generate joins every 1100mm interval between them. These will actually be as separate sheets,lined up/matedseam to seam.


The important thing is for the sheets inserted to be of a set width (not equal width) with one sheet completely variable in width which is just used to close the gap - as this is the best way to make it in real life.

I have looked around the internet and forums for information but don't even know where to begin with this. I'm not sure what I should be looking for but every guess has lead to nothing. Is this not possible in SolidWorks?
Edited by: Phil Greer

 

[Mihail]

I have not SW installed so I try to help you from my mind.

Assuming you have "LHS" and "RHS" do:
Create 2 sheets with arbitrary dimensions:
-First sheet named "EGS" (Equal Gap Sheet) and the dimension name is "egs";
-The second sheet named "VWS" (Variable Width Sheet) and the dimension name is "vws"
Create the assembly: LHS, RHS. Mate this sides.
Dimension the gap. Use DRIVEN dimension for that. Say "LG" (Length of Gap) is the name for this dimension.
Insert "EGS" into the assembly and mate to LHS.
Insert "VWS" and mate to RHS.
Use LINIAR PATTERN to pattern "EGS" N times (N=1 is enough for now)
Create two equations between this dimensions:
1) N = INT(LG/egs)
2) vws = LG - N*egs

That's all. From now you can modify EGS and the distance between LHS and RHS as you need. SW will calculate N and vws for you and update the assembly.

You can assign names to dimensions (SW help)

Note that if N=0 or vws=0 an error occur.

Hope I can help you and YOU understand my english.

Good luck !

 

[Phil Greer]

Every step you've given has worked like clockwork so far, and now we're just stuck on the equation you gave us above. We can see how it'd work, but for some reason we can't get a driven dimension in the gap between sides. It always turns out grey and non-drivable.


What are we doing wrong?

 

[Mihail]

Since I have not SW on my machine, I can not explain that. But:
I think that you mate LHS and RHS using a DISTANCE mate. So, use this distance in your equations (instead LG). Of course, you must modify a little bit the equations if necessary.

Good luck !

 

[Mihail]

Your problem is solved here (SW 2007)



2011-06-21_024303_Assem1.zip

Good luck !

 

[Phil Greer]

Mihail you are a deity! A million tireless thank yous.