Advanced Sheet Metal Design Using NX Cad Challenge_7_ Metal bracket-II
Creating a Bracket with features using NX
Introduction:
Sheet metal gussets are formed with special tooling which has a ridge going across the v opening. The punch is split to the left and right of the ridge as to not be damaged while forming. The sheet metal is bent normally across the v opening except in the area where the ridge is. Typically a spacer separates the ridged section from the rest of the v die, this provides a consistent relief for the sheet metal being bent. It is important to note that the punch needs to also be spaced apart in the same fashion as the die, this will prevent very serious damage. Where the tooling is split the ridge forces the metal into the bend forming a triangular section. This triangular section is known as a gusset and can be used to stiffen or strengthen a bend.
By changing the shape of the forming tool, shown in blue, you can control the finished shape of the gusset. For example a straight tool like the one shown will give you a triangular gusset. A ‘V’ shaped forming tool would give you a square shaped gusset, and so on. Because you are deforming the metal significantly it is not uncommon to see rounded tips on the forming tool, to allow the metal some relief from the process.
The spacers used will typically be rather thin, approximately .025” thick on each side of the gusset. Too thin of a spacer and the gusset tooling will tear through the workpiece and weaken the part. Too much of a spacer and the gusset won’t do much in the way of strengthening the work piece. Typically the gusset material can be stainless steel and should be slightly lower than the top of the die, this will allow you to set your workpiece on top of the die and align it with the back stop before bending.[Reference]
Methodology:
- Sketch Front Section in YZ plane.
- Sketch side profile in zx plane and use contour flange with width of 158mm.
- Make a Normal Cutout of outer and inner features.
- Use break corner to fillet sharp edges with given radii.
- Use unbend and normal cutout to all additional holes and features.
- Use rebend. Use Hem to create 90deg 3mm radius open loop.
- Use flat pattern. Draft the part using base view.
Tools used:
Contour Flange
Creates a base feature by extruding a sketch along a vector, or adds material by sweeping a sketch along an edge or a chain of edges.
Normal Cutout
Use the Normal Cutout command to cut material by projecting a sketch onto the model and then cutting perpendicular to the faces intersected by the projection. You can use planar sketches or 3D curves to specify the section for the normal cutout. If the sheet metal part has multiple bodies, you can specify the target body on which you want to create the normal cutout. You can design the sheet metal part within the context of an assembly and create cutouts while the model is in the formed state.
Break Corner
Use the Break Corner command to round or chamfer sharp corners of a tab or flange. When you create blends on thick edges, to save design time, you can filter out invalid edges.
Hem Flange(open loop)
Use the Hem Flange command to modify an edge of a sheet metal part by folding it onto itself for safe handling or to increase the stiffness of the edge. The hem flange is always created as a secondary feature on a base part. You can create hem flanges on:
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Linear edges and curved edges of a part.
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Connected curves that include a curved edge. You can also create a flange on the linear edge of such hem flanges .
In the following example, a flange is created on the linear edge of a hem flange, and then both the flanges are flattened.
Unbend
Use the Unbend command to unbend a portion of the part to construct cutout features, hole features, or deform features across a bend. You can later reform the bend to represent the true formed state of the model.
Rebend
Use the Rebend command to return an unbend feature to its previous bent state. Any features added after the unbend operation are properly repositioned during the rebend operation.
Model Views:
Front view:
Left view:
Top view:
Isometric view:
Draft:
Conclusion:
The Bracket has been created as per given dimentions and drafted. Files are attached in C7 zip file.