SolidWorks 2011 Parts Bible - Matt Lombard [317]
Also, generally speaking, if the body you are shelling doesn't have faces that are tangent to one another, you will have fewer problems, although faces that are nearly tangent or very pointy can sometimes cause problems.
You can use Shell to hollow out a solid, such as a bottle, as shown in Figure 24.14. You can also use Shell to “shell to outside,” which adds material to the outside and removes the original solid.
FIGURE 24.14
The Shell feature can create multithickness shells.
Using Multithickness Shell
Figure 24.14 shows the PropertyManager set up for a multithickness shell. In this case, the bottom of the bottle is .150 inch thick, while the rest of the bottle is .050 inch. The top of the bottle is selected so that it is open. If you did not select a face to be open, the bottle would simply be hollow with no openings. The image on the right in Figure 24.14 shows half of the bottle in wireframe display to help you visualize the thickness differences. To get a better view of this model, you can find it on the DVD, with the filename Chapter 24 – creased bottle.SLDPRT.
An important part of using the multithickness settings is to remember that SolidWorks will not be able to assign different thicknesses to faces that are connected by tangency. All of the adjacent tangent faces must have the same thickness. Another way to say this is that adjacent faces that are to have different thicknesses must not be tangent to one another. The reason for this is that SolidWorks cannot transition between two thicknesses when the two faces are tangent.
Using Shell Outward
Shell Outward is another option, and is especially useful for bottles. You may be more interested in modeling the contents of a container than the actual container. To help you visualize this idea, think of modeling a liter of frozen water — not the bottle, just water frozen in the shape of the inside of the bottle. Now that you have the contents, you want to create the bottle. This is what the Shell Outward option is meant to do. Figure 24.15 shows the result, where the inside is the original modeled shape, and the bottle shown on the outside was “grown” by the Shell Outward option.
Figure 24.16 shows one of the trickier usages of the Shell feature. This figure shows a planter tray that is manufactured by thermoforming. It may be difficult to tell how to model a part like this, because it could be shelled from either side — the top or the bottom.
FIGURE 24.15
Creating a bottle from a shaped volume
FIGURE 24.16
Getting tricky with the Shell feature
Open the file called Chapter 24 – potting tray.SLDPRT from the DVD. The final feature is used to allow you to better visualize the effects of the shell.
Understanding the Shell workflow
The workflow for using the Shell feature to produce the potting tray part goes like this:
1. Create a solid part where one side of the solid represents the faces of the finished model. The other side may be a simple block. Figure 24.17 shows the model before applying the Shell feature.
2. Initiate the Shell command. In the Faces To Remove selection box, select all the faces that should be removed or will become thickness faces. This should amount to the six faces of the block sitting on top of the tray.
3. Use the Show Preview option if you are having difficulty visualizing the result. Be aware that this option may slow down the operation of the software while the Shell PropertyManager is open, but it will help you see the result based on your current selection.
Figure 24.17
Preparing to shell the potting tray part
Using the Vent feature
The Vent feature is highly specialized and is intended for both sheet metal and plastic parts. Figure 24.18 shows examples of vents.
FIGURE 24.18
Examples of the Vent feature
The part used in Figure 24.18 can be found on the DVD in the file called Chapter 24 – Vents.SLDPRT.
A Vent feature has four main components:
1. Boundary
2. Ribs