SolidWorks 2011 Assemblies Bible - Matt Lombard [168]
Using the Weldment feature
The Weldment button on the Weldment toolbar simply places a Weldment placeholder in the FeatureManager. This placeholder tells SolidWorks that this part is a special weldment part, much in the way that the Sheet Metal feature in sheet metal parts is a placeholder, and denotes a special part type. The Weldment feature moves to the top of the tree, regardless of when you create it in the part history. If you do not create a Weldment feature manually, then one is automatically created for you and placed at the top of the tree when the first Structural Member feature is created. Structural Members are discussed in the next section.
This feature offers only a few special default settings: you can set custom properties that transfer to all cut list items that are created in the current part, and the Merge Result option is deselected by default in weldment parts. The ability to set custom properties is important when multiple weldments go together to make an assembly. To access the custom properties interface, shown in Figure 20.5, select the Properties option on the Weldment feature RMB menu.
FIGURE 20.5
The Weldment Properties interface
The general workflow for creating weldment parts is as follows:
1. Create a new part, and insert a weldment feature.
2. Create a structural layout of 2D sketches, 3D sketches, or use a combination of 2D and 3D sketches to represent a structure to be fabricated by cutting and welding structural shape stock.
3. Ensure that you have a library with appropriate structural shape sketches, properties, materials, and so on.
4. Make sure that you have allowed for sketch lines in the structural layout to represent a corner, centerline, or some other reference in the library structural shape sketch. This can greatly affect intersections between structural members.
5. Assign structural shapes to individual lines in the structural layout. Be sure to understand the rules on using groups.
6. Trim and miter intersections between structural members to suit your design.
7. Add plate entities such as end caps and gussets.
8. Add weld beads as needed.
9. Place the weldment into an assembly and add castings and sheet metal parts, as well as holes and fasteners to attach non-welded components.
Introducing the Structural Member feature
A Structural Member is the basic building unit of weldments in SolidWorks. You can create a Structural Member by extruding or sweeping a profile along one or more path segments, and it may result in a single body or multiple bodies. The path segments may be in the form of 2D or 3D sketches.
Note
A single Structural Member feature may create multiple bodies, with each body corresponding to a single cut length of stock. In other words, the feature name “Structural Member” does not necessarily refer to a single piece of the weldment, although it may.
One limitation of using sketches in Structural Member features is that only two selected sketch entities may intersect at any one location. For example, at each corner of a cube, three path segments intersect, and so you can only select two of those elements at one time to create a Structural Member feature. Because each of the path segments requires a piece of metal, a second Structural Member feature may use the leftover path segments.
When creating the sketch for the weldment, it is important to decide what the sketch represents. For example, does it represent the centerline of the structural elements, or does it represent a corner? You can orient and position structural shape profiles relative to the frame sketch in several ways, with positioning at the shape centroid being probably the most intuitive for closed shapes and a corner being most intuitive for angle channels.
Figure 20.6 shows a single 3D sketch of a simple frame and a Structural Member