Sheetmetal Forming - Punch/Die problem

[dstein_TM]

I am having trouble creating a bend in a part using the sheetmetal app. I usually create simple bends using the bend command, but this will not work now that I am trying to bend along a line that is not straight.
I figure that my next best bet is to use the form command and try creating a die or punch to add the bend. Below is an image of the part (gray) and the forming tool that I created. I keep getting the error

"Feature aborted. Invalid base plane." when I try to form this feature. Does anyone have suggestions on how to solve this problem? I have also attached an exploded section view of the part and forming tool and a top view of just the part.

 

[magneplanar]

dstein_tm,

Perhaps you can consider a different approach, make the form have more of the shape you want and punch (looks like you have a die shape and not a punch) it onto the metal that is a flat sheet rectangle with no other features. After the forming you can trim off any excess just like a tool might do. In some case, the tool would form a precut piece as well. So you could consider making a punch shape from the opposite side and pressing that up to the level you need. I think all you need is to incorporate more of the shape into your punch/die form. It seems that the formed shape now might have issues with the edges of your part shape which are inside the form.

cheers,

M

 

[dstein_TM]

I used this same forming tool, but used it as a punch, and extended the edges so that the part is inside the form. This allowed me to get the bend that I wanted. Thanks for the information.

Another problem showed its ugly face though after I was able to incorporate the bend. I found out that I can't have any of my prior features on the part. I can only incorporate this bend when I remove all prior bevel, chamfer, and radii features. The main bevel that is of concern is one that is added with a swept cut, as shown in the flat image below. Do you have any suggestions on how to keep these features on the part prior to forming it with the punch tool? I have also attached an image of the bent part without the bevel.

 

[magneplanar]

dstein_tm,

I think you need to put more of the features into your form. The part before forming is best if it is flat, or with few features. You should also think of what the form actually looks like. It is just like a copy of the finished inside surface for a punch, or the outside surface for a die. It is possible to form over a prebuilt feature, but i prefer to make the form do the work. In reality, you wouldn't want to make your part with chamfers and rounds and then make a feature on top of them anyway. So place all of that into your form. Be aware of the rules for radii, and features that get close to the value of the material thickness.

If you look at your form, the resulting shape in your lower picture is just like that. So it is the shape of your form that should change if you want to change the shape. If you are intending to change the features along edges, as if compressing the material, then you should consider other methods to produce this.

cheers,

M

 

[dstein_TM]

If I put these features into the form, it wouldn't represent how the manufacturer is actually making the parts. They are machining in the bevels, chamfer, and radii, thus removing material from the part. Will adding the features to the form show this removal of material? Current manufacturing has the machining of the part completed before any bending or forming occurs.

I have had some luck in punch forming the part and then going back and adding the machined features after the form, but this is done by adding them in sets of three (one for each angle of the bend and one for the apex radius of the formed bend). I had a lot of success forming these parts with the simple bend function in the sheetmetal application after the bevels, chamfers, and radii were added. Now that I am trying to add a non-linear bend to the length of the part, though, this part has become a pain in the butt.

 

[magneplanar]

dstein_tm,

In your case you are starting with a pre modified part that already has secondary operations. the form process may not be the best solution in that case, as I mentioned before about considering other methods.

I guess you have to decide how you want the part to be, a representative of the final outcome and let the vendor decide on the steps to get there or, some other option.

Are any of the special features like bend solid an option? I am surprised they form a part that has secondary procedures since that increases the chances of stress fatigue.

cheers,

M


Edited by: magneplanar

 

[dstein_TM]

I know that the form process isn't probably the best feature to use on this part, but I didn't know of any other feature tool that could do bending. I figured that I would be making two separate models for the vendor to represent the manufacturing process better. One to represent the machined flat blanks (with bevels, chamfers, etc.) and one to represent the bent part, even though the model will have machined features added after the bends.

I have never heard of a bend solid feature, can you please give me some insight into this and any other features you think might work?

 

[magneplanar]

an oldie but a good reference...search for others as well

pdf

the bend solid is a surfacing technique and is not meant to duplicate the sheetmetal function but to at least approximate the results from flat to formed or otherwise with a thicken.


Edited by: magneplanar