Freeform alignment

Although Free Form Alignment is considered to be the least accurate method of alignment (because it relies heavily on the skill of the user)

It is sometimes the only option if there are no clearly definable features for which CAD values are known (such as flat planes, geometric elements etc).

When performing a Free Form Alignment the user needs to study the CAD file, and/or the physical part, carefully in order to gauge where to take the probed positions.

For a Free Form Alignment the part needs to be effectively ‘held’ in position in all three axes (X, Y and Z). This holding should occur such that the part cannot move in a space through any translation or rotation.

In this example we are using the Geometric Model. The CAD file for this part is Geometric Model.odx.

From the Alignments Sub-Menu icon , in the elemental toolbar:

Choose the Free Form Alignment button .

Once this button has been selected the Dynamic Points Editor Toolbar appears on the right hand side of the screen.

Holding the cursor in the CAD view, shows it has now changed to a Target Sight . This allows the user to select the points on the CAD surface that are going to be aimed for in the probing process.

Points are selected by simply double clicking on the CAD surface of choice.

Carefully choose a series of key points using Key Features to aim for such as Lines, Indents, Corners and even Projected Aiming Positions on the part.

Click on the Dynamic Points toolbar or select Tools - Dynamic Points - Create a Free Form Alignment.

This displays the Free Form Fit Alignment dialog box, indicating the Positional Coordinates of each chosen point, the Surfaces they lie on, and the Offset values.

Within this box the user can specify the Point Projection Proximity Criteria, which defines the surface area of search around the probe.

Increase the Point projection proximity criteria to 3mm and choose OK

Looking at the Sequence Tree a new item can be seen in the Definition area.

This is the Free Form Alignment created from the Target Points.

Click the Play button from the Main Toolbar.

The Dynamic Point Targets appear for the user to aim for (see right), and this is where the skill of the user comes in, getting as close to the targets as possible.

They appear in sequence order and as each one is probed the next one appears on the screen.

When you have probed all the required points, the Free Form alignment (probing) dialog box changes to the above.

Click the green tick to accept the probed points.

The part will now be aligned to the CAD, this can be seen by the green tick on the Free Form Alignment in the sequence tree.

To check the accuracy of the alignment, highlight the Free Form Alignment in the sequence tree and click the Info tab.

Here you will see the Dynamic Points and if they were found.

Дата добавления: 2015-11-16