Difference between revisions of "The Limitations of Qualifying Tube Shapes using Bender Data"
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'''OUTSIDE THE ENVELOPES: DOES NOT QUALIFY'''<br><br> | '''OUTSIDE THE ENVELOPES: DOES NOT QUALIFY'''<br><br> | ||
− | This second alignment image shows the part with IDENTICAL ANGLES - but the two middle straights are | + | This second alignment image shows the part with IDENTICAL ANGLES - but the two middle straights are <b>increased in length to 10 inches between bends.</b><br><br> |
− | + | The important point to notice is that both parts have the same diameters, the same rotations, and the same bend angles. However, when increasing the lengths, the parts are in danger of rubbing themselves to failure (or colliding with some part of the application). We only changed the lengths, and the part is now likely to fail if the envelope tolerances represent the maximum allowed space that the tube can use before it collides with something else.<br><br> | |
+ | See red cells in the Tangent point/Midpoint grid, and yellow tolerance envelopes where the pink is breaking through.<br><br> | ||
The part is no longer within tolerance - even though all the angle deviations are identical between the two parts.<br><br> | The part is no longer within tolerance - even though all the angle deviations are identical between the two parts.<br><br> | ||
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== Example 2 == | == Example 2 == |
Revision as of 19:26, 24 January 2020
This page explains the major limitations of using bender data for qualifying tube shapes.
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Contents |
What is Bender Data?
Bender data is the data used to setup tube bending machines. Usually, bender data has at three major columns of data - the LENGTH between bends, ROTATION planes between bends, and BEND ANGLE columns. These columns can be used to define the shape of a tube and setup a tube bender.
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The Limitations of Bender Data for Qualifying Tube Shapes
The tube fabrication industry rarely uses bender data to qualify part shapes for a very good reason. |
Illustration of the LimitationLook at the bender data on the right. The two sets are not the same because I've made the MEASURED rotations to be exactly one degree away from MASTER data rotations. |
Visually Demonstrate the Problem of Qualifying with Angles
Unless you can perform 3D trigonometry mentally on-the-fly, the answer to the question above isn't obvious. Even if we make a guess, we can't accurately guess at what tolerance envelope value the part would be considered acceptable. |
INSIDE THE ENVELOPES: QUALIFIES |
OUTSIDE THE ENVELOPES: DOES NOT QUALIFY |
Example 2
We show another smaller part with two tolerance envelope setups. |
The Best Data for Qualification
You've probably already figured out from the examples above that the best data for tube shape qualification is centerline TANGENT POINT data in the Inspection Data menu and in the Reports menu. |