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3D Modeling & CAD for Motorsport: Flat Pattern and Bend Back

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Flat Pattern and Bend Back


00:00 - After forming our sheet metal model with bends and flanges, we'll most likely need to unbend the part to create a flat pattern.
00:07 A flat pattern represents the outline of the shape before it's formed in the manufacturing process.
00:12 This is probably not going to be the same as the flat part before we formed it in CAD.
00:18 We'll look into this more as we progress through this module.
00:21 Flat patterns are useful for creating drawings and manufacturing.
00:26 As with all drawings, we want to illustrate the required details to make the part, like the bend line positions and important dimensions to allow us to check if the finished part has been made accurately.
00:38 From a flat pattern, we can easily export a DXF file, defining the outline of the part, which a laser cutter can then use to cut the part out of flat sheet metal and prepare it for bending operations.
00:51 Exporting files is a bigger topic that requires its own module later in the course so we'll leave it at that for the moment.
00:58 For sheet metal parts that are formed using only the bend tool, we'd actually model something like the flat pattern first before forming it in CAD because the bend tool doesn't add any material to the part so the general shape of the base part doesn't change.
01:13 Like I touched on at the start of this module, it's important to understand that the initial flat base is likely not going to be the same as the final flat pattern.
01:23 That's because as we add bends where reliefs are used, these reliefs are added to the sheet metal body.
01:30 If we're modelling using the flange tool, this process adds material and a bend to an existing part.
01:36 If we add features like holes while the part is in its formed state, this could help us position the holes referencing geometry that is already formed, as opposed to adding the hole and then bending the part and having to check and potentially adjust the hole position.
01:52 These reliefs, flanges and added features will be included in the flat pattern which is why it's important to model our part completely first and then create the flat pattern as a final step for drawing or manufacturing.
02:06 Let's look at an example to see how this all works in pracice.
02:09 We'll start with our same model from our earlier bend module.
02:13 Let's remove the bend on the corner of the part and use the flange tool to make flanges on two of the unbent edges, 15 mm high at 90° and then set the bend position preference to adjacent.
02:27 We'll also override the two bend corner rules to change the relief to a circular shape like the other side.
02:34 We're missing reliefs on the other two corners but that's OK, we don't need them for this example.
02:39 To make a flat pattern, we're going to use the flat pattern tool found under our create tab in our toolbar.
02:46 On choosing this tool, we need to select our stationary side just like we did with our bend tool.
02:52 All other sides of the part will be flattened to match this stationary side.
02:57 We now have the ability to modify our flat pattern using the tools from the flat pattern solid or surface toolbars.
03:04 We could add features like holes for example to our flat pattern as it may be easier to add them to a flattened part, however if these features are added to the flat pattern, keep in mind that they're only on the flat pattern timeline so they'll only exist on the flat pattern and won't be included in our 3D part when we're finished viewing the flat pattern.
03:25 This may or may not be a problem depending on what you're working on.
03:28 If we did want to model features on a flat part and have these carried back over to the 3D part, then we can use the unfold tool instead, found under modify in the toolbar.
03:39 This works in a very similar way to the flat pattern tool where we select the stationary side but we also select the bends we want to unfold.
03:47 We can then add features to our part and select refold in the toolar.
03:52 All these processes will be captured in the timeline for our model.
03:56 The unfold function doesn't replace the need for a flat pattern though.
04:00 We still need to use this as a final step before exporting files or making technical drawings.
04:05 Back on the flat pattern, we can also see the bend centrelines and the extent lines, showing the area that will form part of the bend radius when the part is bent.
04:16 These can be hidden under the bodies tab in the browser if needed for drawings or when exporting the DXF using the icon in the toolbar so we only get the outine of our flat pattern.
04:28 Again, we'll come back to this in a coming module.
04:31 Finishing our flat pattern, the model space changes back to the view of the formed part.
04:36 However, now we have the flat pattern in our browser.
04:40 We can right click and activate this to go back in and edit or view the flat pattern.
04:46 Or if we make changes to the flat part, we can update the flat pattern as well.
04:51 Naturally we've wrapped up our sheet metal modelling basic section with the final process of creating a flat pattern.
04:57 Put simply, what you need to know is that the create flat pattern tool allows us to flatten our final formed part, including the flanges and bend reliefs which can then be used for drawings and manufacturing.
05:10 Once our flat pattern has been created, we can still modify the formed part and update or view the flat pattern from our browser.

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