Chapter 0 Assembly Mode

This chapter introduces:

Assembly Placement Constraints

Assembly Interface

5.1 Assembling Components

Just as features are added to one another to create a part, parts can be assembled to one another to create an assembly. The parts can be assembled individually or as a member of a subassembly to create a higher level assembly. The parts and subassemblies are referred to as components.

Constraints are specified to locate components parametrically with respect to existing components and features. Similar to the interdependencies between features in a part, parent-child relationships also exist in assemblies. Any references made to other components when assembling a new component create parent-child relationships. The placement constraint options shown in Table 5-1 can be used.

Table

The examples on the following pages illustrate the use of constraints to place components in an assembly.

Example 1 (Mate and Align):

Figure 5-

Table 5-

Figure 5-

Example 2 (Mate Offset and Align):

Figure 5-

Table 5-

Figure 5-

Example 3 (Mate and Align):

Figure 5-

Table 5-

Figure 5-

Example 4 (Align Offset, Align, and Mate):

Figure 5-

Table 5-

Figure 5-

Example 5 (Insert and Mate):

Figure 5-

Table 5-

Figure 5-

Example 6 (Insert, Orient, and Mate):

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Table 5-

Figure 5-

The first two constraints fully define the placement; however, Orient is used as an additional constraint to define the orientation of the bolt.

Example 7 (Tangent, Align, and Orient):

Figure 5-

Table 5-

Figure 5-

Example 8 (Edge On Srf, Tangent, Align, Orient):

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Table 5-

Figure 5-

Example 9 (Coord Sys):

As illustrated in the previous examples, a combination of the constraints must be used to fully define how components are to be assembled. The Coord Sys constraint can be used alone.

Figure 5-

Figure 5-

5.2 Assembly Interface

When constraining components in an assembly, the Component Window and the Component Placement dialog box appear as shown in Figure 5-19.

Figure

The Component Placement dialog box, shown in Figure 5-20, is the control center for the assembly process. It appears every time you choose to assemble a new component or redefine the placement of an existing component.

At the top of the Component Placement dialog box, you are given the choice of two tabs: Place and Move. This training course discusses the options for the Place tab only. The Move tab contains options for placing components nonparametrically and is discussed in the advanced assembly courses.

At the top of the Place tab, there is the Display Component In section; this contains the options Separate Window and Assembly. These options control the location of the new component as you are defining constraints to assemble it. Selecting Separate Window locates the new component in the Component Window as shown in Figure 5-19. Selecting Assembly locates the component in the main window with the assembly. As a new user, you may find it helpful to select the Separate Window option.

Figure 5-

The Constraints section of the dialog box shows a list of the currently defined constraints. If there is an offset distance associated with the constraint, it is also displayed here. You can remove an existing constraint at any time by selecting it and then selecting the button. Selecting the button allows you to add a new constraint.

The Constraint Type section contains a pull-down menu from which you select the type of constraint you are adding. As constraints are added, the number of options available on the menu reduces to list only the possible constraints. For example, after adding a Mate constraint, Coord Sys is no longer available.

The Component Reference and Assembly Reference sections are used to select the component constraint reference and the assembly constraint reference, respectively. Upon selecting the appropriate button, you can select the reference on the component in the Component Window or the reference on the assembly in the Main Window. The name or type of reference appears adjacent to the button.

The Offset section of the Component Placement dialog box displays the value you enter for the Mate Offset and Align Offset constraints.

The Placement Status section gives you the status of the component being placed. Possible messages include the following:

No Constraints

Partially Constrained

Constraints Invalid

Fully Constrained

The three buttons shown in Table 5-10 appear at the bottom of the Component Placement Window.

Table 5-

The placement of a component can be redefined by choosing Component, Redefine, and selecting the component. The Component Placement dialog box appears and displays all the constraints used to originally place the component. The constraint type, component references, and assembly references can be changed. Figure 5-21 shows the possible selections when redefining a component placement. As each constraint is selected in the Constraints section of the dialog box, the corresponding assembly and component references highlight on the model for easy identification.

Figure 5-

The Model Tree lists all the parts and subassemblies that make up an assembly. Selections can be made directly from the Model Tree for commands such as Modify, Delete, and Suppress.

To expand the tree and view the components of a subassembly, simply click on the + symbol beside the assembly name. To compress the expanded section, click on the - symbol. See Figure 5-22.

Figure 5-

After you complete this exercise, you will be able to:

Create Assemblies

Modify Assemblies

Redefine Assemblies

Choose File, New.

Select Assembly in the New dialog box.

Enter [practice] as the name.

Select the button.

Choose Component, Assemble and select ablock.prt in the Open dialog box.

Select the button.

The part ablock.prt is automatically assembled and displayed in the Main Window.

Figure 5-

Choose Assemble and select bblock.prt. The Component Placement dialog box appears.

Initially, the new component appears in the Main Window because Assembly is selected in the Display Component In section of the Component Placement dialog box. Unselect Assembly and select Separate Window as shown in Figure 5-24. The new component should now appear in the Component Window.

Figure 5-

The first constraint mates surface 6 on bblock.prt and surface H on ablock.prt. See Figure 5-25.

Select Mate from the Constraint Type pull-down menu.

Select the button in the Component Reference section.

Read the information in the Message Window. Select surface 6 on bblock.prt in the Component Window. Use Query Select if necessary.

Select the button in the Assembly Reference section.

Read the information in the Message Window. Select surface H on ablock.prt in the Main Window. Use Query Select if necessary.

The Component Window goes to the background when a selection is made in the Main Window. Move the main Window and select the title bar of the Component Window to bring it forward.

Look at the Component Placement dialog box. The Placement Status now says, "Partially Constrained". The first constraint has been added and the second can now be defined.

The second constraint aligns surface 3 on bblock.prt and surface B on ablock.prt. See Figure 5-25.

Bring the Component Window forward before making any selections. This makes it easier to select the constraint references.

Select Align from the Constraint Type pull-down menu.

Select the button in the Component Reference section.

Read the information in the Message Window. Select surface 3 on bblock.prt in the Component Window. Use Query Select if necessary.

Select the button in the Assembly Reference section.

Read the information in the Message Window. Select surface B on ablock.prt in the Main Window. Use Query Select if necessary.

Look at the Component Placement window. The Placement Status still says, "Partially Constrained". With the current constraints, bblock.prt can still lie anywhere on surface H while aligned to surface B. A third constraint is required to fully constrain it.

The third constraint aligns surface 1 on bblock.prt and surface A on ablock.prt. See Figure 5-25.

Bring the Component Window forward before making any selections. This makes it easier to select the constraint references.

Align from the Constraint Type pull-down menu.

Select the button in the Component Reference section.

Read the information in the Message Window. Select surface 1 on bblock.prt in the Component Window. Use Query Select if necessary.

Select the button in the Assembly Reference section.

Read the information in the Message Window. Select surface A on ablock.prt in the Main Window. Use Query Select if necessary.

Look at the Component Placement window. The Placement Status now says, "Fully Constrained".

Figure 5-

Select the button to see the placement of bblock.prt in the assembly. It should be as shown in Figure 5-26.

If the component is not where expected, select the button, and repeat the previous steps.

If the placement is correct, select the button.

Figure 5-

Assemble bblock.prt again as shown in Figure 5-27.

Figure 5-

Choose Component, Assemble and select bblock.prt.

Mate surfaces 4 and H. See Figure 5-28.

Mate surfaces 6 and 4 (of the assembled bblock). See Figure 5-28.

Mate surfaces 3 and B. See Figure 5-28.

Figure 5-

Read the Placement Status in the Component Placement dialog box. Why are the constraints invalid? Select the button; do not select the button. The Message Window also indicates that the component placement constraints are invalid.

Bring forward both sub windows. Review the constraints that were used by selecting each constraint listed in the Constraints section of the Component Placement dialog box. Note that as each constraint is selected, the references used on both the component and the assembly are highlighted.

Select the third constraint. Choose Align from the Constraint Type pull-down menu.

Select the button. The assembly should now appear as shown in Figure 5-27.

Select the button to complete the component action.

Choose Component, Assemble and select pin.prt.

Assemble the component as shown in Figure 5-29. The final assembly should appear as shown in Figure 5-30.

Figure 5-

Figure 5-

Assemble ablock.prt and bblock.prt. Attempt to assemble them using the Assembly option in the Display Component In section of the Component Placement dialog box.

Figure 5-

From the top level ASSEMBLY menu, choose Component, Redefine and select the second instance of ablock.prt in the assembly.

In the Component Placement dialog box, delete the first Align constraint by selecting it in the Constraints section and then selecting the button. Do the same for the second Align constraint.

Using the button, add new constraints that position the component as shown in Figure 5-32.

Figure 5-

Choose Info, Component from the menu bar.

Select pin.prt. The Component Constraints dialog box appears as shown in Figure 5-33 (the order of the constraints depends upon the order in which you added them).

Figure 5-

Select each of the constraints listed in the dialog box. As you do, notice that it highlights the reference surfaces on the model.

Select the button. An Information Window opens with additional information about the component. The information is written to a text file called pin.memb, which is stored in the current working directory.

Select the buttons on the Information Window and the Component Constraints dialog box.

Choose Component, Delete from the ASSEMBLY menu and select all components except the first instance of ablock.prt. Remember that parent-child relationships exist.

Assemble bblock.prt using Align offset as one of the constraints. Align Offset surfaces 6 and A by a value of [-1.0]. A negative number is used because the offset arrow that appears indicates the positive direction. The assembly should appear as shown in Figure 5-34.

Figure 5-

Choose Modify from the ASSEMBLY menu. The default option on the ASSEM MOD menu is Mod Dim.

Select the base feature of bblock.prt (not the circular cut); all the dimensions for the feature appear as well as the offset dimension.

Select the offset dimension and enter 2.

Choose Done/Return, Regenerate, Automatic.

Choose Modify in the ASSEMBLY menu.

Choose Mod Assem.

Select bblock.prt. Only assembly dimensions (the offset value) appear this time.

Select the offset dimension and enter [0.5].

Choose Done/Return, Regenerate, Automatic.

Save the assembly and Erase it from memory.

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After you complete this exercise, you will be able to:

Create Multi-Component Assemblies

Create the assembly shown in Figure 5-35 using the components ablock.prt, bblock.prt, and rocker.prt.

Figure 5-

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