Pro/ENGINEER TutorialDept. of Mechanical EngineeringUniversity of Alberta

Lesson #5: Revolved Features, Patterns, and Copies

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Overview of this Lesson

This lesson will introduce you to the following operations:Creating Revolved Features

made by creating an open or closed edge and revolving it around an axis. Can be used for protrusions, cuts, or slots.

Creating Patternsgenerates multiple parametrically-related instances of any type feature

Copying Featurescopying a single feature or group of features by translation, rotation, and mirroring

To demonstrate these features, we will be creating several different parts. The parts are totally independent of each other, so you can jump ahead to any one of these:

1. Revolved Features o A Revolved Protrusiono A Revolved Cut

2. Patterned Features o A Radial Pattern of Holeso A Patterned Array of Grouped Features

3. Copied Features o Copying with the Same Referenceso A Translated Copyo A Rotated Copyo A Mirrored Copy

4. Design Considerations

o Some things to think about when designing with complex features

Revolved Features

A revolved feature is an axisymmetric shape that is created by revolving an open or closed section view by a specified angle around a central axis. The section can represent a protrusion or a cut, that is, it can either add material or take it away. We are going to create the part shown in Figure 1.

Figure 1

This is a V-pulley that has been cut away to show the cross sectional shape. The part is shown on page 391 of Fundamentals of Graphics Communications (Irwin Graphics Series). The central shaft has been modified somewhat in order to demonstrate a cut operation. The finished part will have only three features.

Start up Pro/E as usual. Create a part called v_pulley and set up the default datum planes.

Revolved Protrusion

The first part feature will be a revolved protrusion:

Feature > Create > Solid > Protrusion > Revolve | Solid | Done

Pick One Side | Done, and DTM3 as the sketching plane, and DTM1 as the Right reference plane. Let the feature creation arrow come towards the front.

The most difficult operation for this part is generating the sketch for the cross section. We are going to revolve this 360 degrees around the central axis. For reference, here is the final dimensioned sketch:

Figure 2

Study this carefully, since several dimensions have been implicitly determined by the Sketcher rules. Using

Sketch > Mouse Sketch

set up a freehand sketch that looks something like this:

Figure 3

Don't forget to add a centre line by selecting

Sketch > Line > Centerline | Vertical

Align the centerline to the datum plane. Also, the sketch must be closed, so you will sketch (and align) a line down the center of the section.

To dimension the section, here is a new trick: To dimension a diameter, click first on the outer edge, second on the axis, third on the outer edge again, and fourth (middle button) to place the dimension. Try to dimension and regenerate the sketch yourself. If you have trouble, go back and look at the dimensioning scheme shown in Figure 2. You may have to give some additional dimensions explicitly to over-ride the Sketcher rules. If you are having trouble getting a successful regeneration, just get as close as you can for now - simplify the geometry until you do get successful regeneration. Don't get tangled up in Sketcher problems since we are really interested in seeing how the revolve works.

When you get a successful regeneration, select Done. Then in the REV TO menu, select

360 | Done

to specify a 360 degree rotation of the sketch around the axis. Your part should look like Figure 4.

Figure 4

Now we will add the central hole.

Revolved Cut

To create the cut:

Create > Cut > Revolve | Solid | Done > One Side | Done

Use the same sketching and reference planes as before (DTM3 and DTM1) and create the following sketch:

Figure 5

Don't forget to align the top and bottom edges of the cut line, and make sure the material removal arrow points inwards. When the sketch regenerates successfully, select Done and then

360 | Done

The last job to do for this part is to create some rounds. There are four of them, all with a radius of 3, shown in Figure 6.

Figure 6

All the rounds can be created at the same time, provided that you want them to always have a common radius. If you want to change the radius of one or two of them, you'd have to create them separately. It may be necessary when you are selecting the edges to reorient the part to see the edges clearly.

As a final note, you might note that we could have created this part using a single revolved feature that would include the central counter-bored hole and the rounds into the revolved solid we made here. We will discuss the consequences of this at the end of the lesson.

Patterned Features

Creating a feature pattern is similar to a multiple-copy, except that it is possible to change the geometry parametrically of each member in the set. The pattern is based on a single instance of the feature - called the pattern leader. Once created, pattern becomes a single feature. All instances of features in the pattern can be modified simultaneously. This is best shown by a couple of examples.

Creating a Radial Pattern - A Bolted Flange

A common element in piping systems is bolted flanges. Here is how to create a pattern of bolt holes. In addition, we will set up a couple of relations to control the geometry based on the specified number of holes.

Start a new part called flange and set up the default datum planes. Create the circular disk with central hole shown in the figure below. The outer diameter is 16, the hole diameter is 8, and the disk is 3 thick. Note that the disk is constructed on DTM2.

Figure 7

Now create a hole in the disk. This will be the pattern leader:

Create > Solid > Hole > Straight | Done > Radial | Done

Use the upper surface of the disk as the placement plane, and position the hole at about the 5-o'clock position. See the figure below. Select the axis of the disk, and datum DTM1 for radial (polar) dimensioning with an angle of 30 degrees. The radial distance of the hole from the axis is 6. Make the hole one-sided, thru all, and with a diameter of 1.

Figure 8

We are now going to make a total of 8 copies of the hole spaced equally around the flange. Select

Pattern > [click on the hole] > Identical | Done

To create a pattern, you first select a dimension that will be incremented to create instances in the pattern. The dimension can be linear or angular. For the bolt circle, we want to increment the angular position, so click on the 30 that shows the angle between the hole and the datum plane. Now enter the increment to be used in the chosen direction, that is, 45 degrees. Since this is all we want to increment, select Done, and enter the total number of instances of the hole, 8. If you want to make an array pattern, you could now select a second dimension. We don't want to, so select Done. The part should now regenerate and show you the following bolt pattern.

Figure 9

Suppose we wanted to change the number of bolts on the flange. Do we have to do all this over again? The answer is no - we can use relations! In the PART menu, select

Relations

and click on the 2nd hole in the bolt pattern (the one at about 3-o'clock). You should see all the dimensions that control the pattern like this

Figure 10

Take note of the symbol for the angular dimension between bolts (d12), the angle of the first bolt from DTM1 (d10), and the number of holes (P0). We can Add a couple of relations for these by entering the following:

/* angular separation of holesd12 = 360 / P0/* orientation of first holed10 = d12 / 2

Before you leave the Relations menu, select Switch Dim. Go back to the PART menu, select Modify, and click on any of the holes. Change the number of bolt holes to 12, then Regenerate the part. Check again for 6 holes, 5 holes. Don't forget you have to regenerate after each modify.

Use Modify to change the diameter of any one of the holes to 2. With the diameter of 2, try to create a pattern of 24 holes. What happens? Remember that we specified a pattern of identical features. This does not allow the instances to intersect; other options would allow it. To recover from this error, select

Undo Changes > Confirm

Try to modify the separation angle between holes or the placement of the pattern leader. What message does Pro/E give you?

A Pattern of Grouped Features

The bolt circle pattern was pretty straight forward - we only duplicated a single feature, and its size/shape stayed the same for each copy. We can go much farther than that by using grouped features.

We are going to create the part shown below. The pattern leader is the feature on the left in the front row. We will use a pattern to set up two rows with the dimensions incrementing along each row, and between rows.

Figure 11

Start a new part (including datum planes) and create the rectangular base (solid protrusion 20 x 30 x 3 thick). Now create a circular solid protrusion (diameter 2, up 3 from the lower edge of the plate, over 5 from the left edge, and with a height of 2). Create a coaxial hole on the circular protrusion going completely through the part. Finally, add a 0.25 round on the circular edge where it meets the plate. The part should look like this:

Figure 12

Before we can create the pattern, we have to group all the features on the circular protrusion. In the FEATURE menu, select

Group > Create > Local Group > [pocket]

Now pick on the protrusion, the hole, and the round. Then select Done Sel > Done

You should be informed that the group pocket has been created. Now, still in the GROUP menu, select Pattern and pick on the protrusion. You should see all the dimensions associated with the group as shown below:

Figure 13

First Pattern Direction

pick on the 5.00 dimension, and enter the increment 10 pick on the diameter of the protrusion 2.00, and enter the increment 1

pick on the diameter of the hole 1.00, and enter the increment 1 select Done enter the number of instances 3

Second Pattern Direction

pick on the 3.00 dimension, and enter the increment 12 pick on the height of the protrusion 2.00, and enter the increment 3 pick on the protrusion diameter 2.00, and enter the increment 3 pick on the hole diameter 1.00, and enter the increment 2 select Done enter the number of instances 2

All the patterned pockets should now be added to the part. Go back to the PART menu, and experiment with the Modify command. What dimensions are available for modification (this may depend on what feature you pick on)?

Copying Features

In the section above, we saw how to create a multiple-instance pattern of a single feature or a group of features. The pattern could only be created by incrementing one or more of the feature's dimensions. The Copy command allows more flexibility in terms of placement and geometric variation, but only creates one copy at a time. There are several options available with Copy, and we will create several different simple parts to illustrate these.

A Same Ref Copy

We are going to create the part shown in Figure 14. The bracket on the left is the original, and the one on the right will be the copy.

Figure 14

Start by creating a new part with the default datum planes. Create a rectangular solid protrusion on DTM2 that is 10 x 20 x 2 thick. For the vertical feature, the sketching plane is a Make Datum that is offset from DTM1 by 5. Thus:

Create > Solid > Protrusion > Extrusion | Solid | DoneMake Datum > Offset > Sel By Menu > Datum > Name > DTM1Enter Value > [5] > Done

Select the top of the rectangular base as the Top reference plane. Then sketch the protrusion as shown below:

Figure 15 When you get a successful regeneration, select a Blind depth of 1.

Now, we are ready to copy the feature. We want the copy to be 10 to the right of the first. If the geometry of the first feature changes, we want the copy to change too - it will be dependent.

Copy > Same Refs | Select | Dependent | Done

Pick on the protrusion and select Done Sel > Done.

The Group Elements Window will open up. This is giving us some options about which dimensions in the copy we want to vary. At this time, we will only change the distance from the left end. Move the cursor up and down the listed dimensions. As you do this, the dimension will highlight on the model. Select the dimension 5 that locates the protrusion, and select it. Then select Done. You are prompted for a new value for this dimension; enter15, then select OK from the elements window. The new protrusion should appear at the right.

What happens if you try to Modify the hole diameter on the first protrusion? The height dimension on the copy?

Delete the copy and recreate a new independent copy. Try the same modifications.

A Translated Copy

We will make the part shown below. The original feature is again at the lower left.

Figure 15

You can keep the same base plate as the previous part (10 x 20 x 2 thick, on DTM2). Create a solid protrusion near the lower left corner of the plate (dimension 4 from left surface, 3 from lower surface, diameter 3, blind depth 5). See Figure 16.

Figure 16

Now we will copy the feature and change its diameter at the same time:

Copy > Move | Select | Dependent | Done

Click on the protrusion, then Done.

Translate > Plane > Plane > Sel By Menu > Datum > Name > DTM1

Check the direction of the translation arrow, and enter the distance 10. To move it again:

Translate > Plane > Plane > Sel By Menu > Datum > Name > DTM3

Check the direction of the translation arrow ( you may have to flip it), and enter the distance 5. Then select:

Done Move

In the GP VAR DIMS menu, select the diameter of the protrusion as variable, then Done. Enter the new value 1.5. Then select OK.

A Rotated Copy

We will use a rotated copy to create the part shown in Figure 17 - a large circular pipe with two pipes joining it off-axis. At the same time, we will see a case where feature creation order can be used to advantage.

Figure 17

The original side pipe is on the left, the copy is on the right. It can be obtained by a 180 degree rotation from the original.

Start by creating a circular solid both-sides protrusion from the sketching plane DTM2. Sketch a diameter of 20 and set blind depth of 20. Do not add the inner surface of the pipe at this time - we will do that later.

For the side branch, use DTM3 as the sketching plane (Top reference DTM2) and sketch an 8 diameter circle aligned with DTM2 and with a center 5 from DTM1. Check the feature creation direction arrow. Make the protrusion one-sided with a blind depth of 15. This will extend it outside the circumference of the major pipe.

Create a one-sided, thru-all, coaxial hole on the axis of the branch pipe. Use the placement plane DTM3 and make sure the direction arrow is pointing the right way. The hole diameter is 7. The part should look like the figure below.

Figure 18

Now we are ready to copy the branch pipe. We may want to change the size of the copied branch pipe, so we will make an independent copy:

Copy > Move | Select | Independent | Done

Pick on the branch protrusion and hole, then select Done. Now we specify the rotation:

Rotate > Crv/Edg/Axis

and pick on the axis of the main pipe. Enter the angle of rotation 180. Then select:

Done Move > Done

to keep all the existing dimension. However, we have created an independent copy, so we could come back and change any dimensions of the copied pipe. All the elements of the copy have been defined, so click OK. The model should now look like the figure below.

Figure 19

Now we can add the central hole of the main pipe. Make it a straight, coaxial, both-sides hole from the placement plane DTM2. Make it Thru All in both directions, with a diameter of 19.

Experiment with the Modify command, changing dimensions of both the original and the copy. You can also modify the rotation angle. What happens if you modify the diameter of the main pipe to 12 and hole to 11? The part will certainly regenerate, but is clearly wrong. However, the error is relatively easy to fix. Another possibility for creating the part (that would cause even greater difficulty) is the following:

create main pipeAs before.

create central holeAs before.

create side branchWe couldn't do this from DTM3 since that would be inside the pipe. We would have to create a Make Datum using an offset of 15 from DTM3 and create the branch towards the main pipe using an Up To Surf depth.

create the side branch holeWe could use the planar face of the branch as the placement plane for a coaxial hole with a depth specified as Thru Next (through the next part surface encounterd).

These steps would create the same geometry. However, we would have a big problem if we tried to reduce the diameter of the main pipe to less than 18, since the side branch solid protrusion would not intersect the surface of the main pipe as required by

the Up To Surf depth setting. The part would not regenerate, and we would have to spend some time fixing the model. The moral is, you have to plan ahead!

A Mirrored Copy

The final copy option we will look at is the mirror copy. Mirroring is very useful, obviously if you have symmetric parts, you only have to create half and then mirror to get the other half. We will create the simple mirrored, curved slot shown in Figure 20.

Figure 20

Start with a rectangular base plate (12 x 20 x 2), centered on DTM2 so that the datum plane DTM1 is on the centerline of the plate. Create a single Slot using the dimensions shown in Figure 21.

Figure 21

Add a 45 x 0.5 Chamfer to the upper and lower edges of the slot. The mirror copy is easy:

Copy > Mirror | Select | Dependent | Done

Pick on the slot and the chamfers, then select Done. To specify the mirror plane:

Plane > Sel By Menu > Datum > Name > DTM1

That's all there is to it! Try to Modify the mirrored copy. Note that for mirrored features, all the defining dimensions are shown on the original. You should investigate to see what happens if you make an independent mirror copy of the same slot.

Design Considerations

We have covered a lot of ground in this lesson, and hopefully added a lot of ammunition to your modeling arsenal! We have also seen how the feature creation options can control the behaviour of the model. So, now is a good time to say a few words about part design.

The first part created in this lesson, the V-pulley, consisted of only three features (the revolved protrusion, the revolved cut, and the rounds). It was mentioned that it would be possible to create the pulley completely from a single feature (a revolved section that included the inner bore and the rounds). The last part involved only four features and a pattern.

You must consider the following when trying to put a lot of geometry into a single feature:

How easy will it be to modify the feature later? If the geometry is very complex, it may take a lot of work to get the single

feature to create properly. Perhaps it would be more efficient to create a number of simpler features that would have the same resulting geometry.

If you plan to do some engineering analysis of the part, for example a Finite Element Analysis, then minor features such as rounds, chamfers, small holes, etc., will only complicate the model, perhaps unnecessarily. They will also lead to increased modelling effort downstream. These features are normally added last. We will see in a later lesson how they can be temporarily excluded from the model (called suppressing the feature).

If the entire part is contained in a single feature, it may be difficult later to make major changes to the part that may not be feasible using that feature.

When creating the patterns and copies, we discovered the ways that duplicated features could be modified, either during feature creation or after the fact. We also saw some of the ramifications of feature order in the model.

These considerations should be in the back of your mind as you plan the creation of each new part. It is likely that there are many ways in which to set up the part, and each will have advantages and disadvantages. The more you know about the Pro/E tools, and the more practice you get, the better you will be able to make good decisions about part design. Good planning will lead to an easier task of part creation and make it easier to modify the geometry of the part later. Like most design tasks, the model design is subject to some iteration. We will discuss in a later lesson some of the tools that Pro/E provides to allow you to change the structure of your model if it becomes necessary or to recover from modeling errors.