Mahr | Application Tips

Measuring contours with tangential elements

Marketing Team
Measure contours with tangential elements

Workpiece radii can have a variety of shapes and contours. Measuring them is part of daily business in production. Mahr offers users a process that considerably simplifies the measurement of even complicated workpieces.

Calculating the tangential circle and tangential transition points

To calculate the tangential circle that transitions into straight lines, the two regression lines to the right and left of the circle must first be created. The tangential circle is then calculated using the command "Tangential circle to straight line(s)". Operators first select the two regression lines and define the area of the circle with the mouse pointer. The MarWin software then automatically generates the tangential transition points and the regression circle. The regression lines can be defined manually with a mouse click or by manually or automatically creating profile areas. It is also possible to edit and adjust the straight lines after the command has been completed. "However, the area of the regression circle that merges tangentially into the straight lines can only be changed subsequently if it was previously defined as a profile area," says the application engineer.

Tangential transition With the "Tangential transition" command, the regression lines and the regression circle as well as the transition points can be generated automatically. To do this, users simply define the areas with a mouse click or beforehand with the "Profile area" command. When editing the tangential circle, the software displays the areas of the tangential straight line and the tangential circle or the names of the profile areas. As with the regression circle, the circle can be displayed as a full circle. It is also possible to filter the profile in the area of the circular arc in order to eliminate roughness components. "The tangential circle is fitted in such a way that the sum of the distance squares of the measured profile points in the selected circle segment is minimal, taking into account the transition points of the tangential straight lines," says measurement expert Schlie.

 

Edge breakage and edge rounding The tangential points can also be used to measure edge breakage or edge rounding. The calculation of a tangential circle including the adjoining straight line is carried out with very low measurement uncertainty. The prerequisite for this is tangential, straight contour sections into which the circle merges. Even for contours with high roughness and small circle segments, the "tangential transitions" and "tangential circle" functions work reliably and robustly, so that the repeatability of the results is extremely high.

 

Calculation of the tangential circle with only one straight line The calculation of the tangential circle is also possible if the circle merges into only one straight line on one side - in this case, the tangential point between the circle and the straight line is formed on one side. On the other side, the operator limits the circle with a mouse click or by an intersection point between the profile and element (parallel straight line, circle of point and angle ...). Conclusion: With this measuring method and MarWin, users can easily and precisely measure the contours of even complex workpieces after just a short training period.

Measuring radii on workpieces is a very common inspection task in industrial production. Radii occur in very different contour shapes: A radius can merge into another radius or into a straight line; the transition can be smooth, i.e. tangential, or end in an edge, an angle or any linear contour. A special measuring method is required to calculate radii with tangentially connected contour geometries and the transition points of the neighboring contour elements. With the contour measuring device and the "Method for measuring the contour of a workpiece with tangentially adjoining contour geometries", Mahr has developed and patented a process/routine specifically for this purpose. With a flowing, i.e. tangential transition, it is difficult to distinguish exactly where the circular arc ends and the straight line begins. However, a different choice of start and end point often makes a significant difference when calculating the radius. "Mahr's patented process calculates these transition points reproducibly and accurately. This allows reproducible, process-reliable results to be achieved independently of the operator. The measurement can be carried out tactilely with MarSurf devices or optically with MarShaft SCOPE measuring stations," explains Jakob Schlie, Application Engineer at Mahr. "And thanks to the MarWin software platform, the evaluation is identical for all measuring stations, so no training is required – operators can measure radii and tangential transitions directly using this method with the various Mahr measuring stations."

Info
To top