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What is sweep?
Sweep is type of extrusion where the cross section is extruded following a trajectory. Curved tubular or box structures normally modeled by sweep command. Like material addition, sweep could also be used for material removal and making shell kind of geometry. For example, if you want to create a round but curved tube, then you can think of thin sweep protrusions.
An example of creating sweep
Let’s take an example of creating an “S" shaped tubular model. For modeling this you have to go to insert>sweep>thin protrusion. Once you have gone there, you will find the sweep dialogue box. Next you need to define trajectory (the “S" shape curve). Either you can sketch the curve now itself or you can use any old curve. As soon as you finish defining trajectory, you have to specify one of the following options:
Merge end: by clicking this option you will tell pro engineer to merge the ends of the created geometry with the adjacent solid, wherever possible.
Free ends: Pro engineer will not merge the ends with adjacent solids.
Now, you will be directed again to the sketcher mode for sketching the cross section, in our case it will be a circle of say 25mm. you will be asked to enter the thickness of the tubular model (enter 5). Now click on the “ok" and BINGO!! You got your model of “S" tube ready.
Limitations of sweep
Sweep is quite easy and user-friendly command but you cannot use different cross sections at different locations of the trajectory. Take the case of the above example, if you wish to use different diameter of the circular cross section at different locations of the trajectory using sweep, you cannot.
This feature is added to variable section sweep, you can create sweep with different shape and sized cross sections at different locations of the trajectory.
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Some good words to keep in mind
Before moving to variable section sweep, please note that a sweep may fail under following circumstances:
- If you are using a trajectory, which is crossing itself.
- If you dimension a cross section with a fixed entity in such a way that the dimensions does not allow it to orient further but as a result of sweep the cross section have to orient.
- You are using too small radius in any point of the trajectory, such that the sweep geometry is intersecting itself.
Variable section sweep
So, by this you are well aware about the fact that you can choose different shaped cross section for variable section sweep. Now let’s go directly to an example, say you have to model the “S" tube again, but this time upper and lower bend portions of the tube is circular and middle straight portion is rectangular.
Go to insert>variable section sweep. In the reference tab you need to select the trajectory. You can either create the curves before starting variable section sweep or in between the command itself. If you want to sketch the curve in the variable section sweep command itself, then you have to click on the datum curve located at the right hand side of the pro engineer window. Once you are done with the trajectory/trajectories you need to sketch the cross sections by clicking the icon named create or edit sweep section. After defining the entire parameters click on the “green tick mark" and you will see the variable section sweep.