Engine Valve Guide (dcu_mtmlib1.dll)

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Engine Valve Guide (dcu_mtmlib1.dll)

This MtmLib1 DLL is designed to assist in analyzing an engine valve guide that is modeled as three approximately circular sets of points on parallel cross sections of an imperfect cylinder. The functions in the DLL may be suitable for other applications as well.

 

Within this section:

Virtual Clearance (Virtual Clearance)

Circularity (Cross-sectional Circularity)

Circular Runout (Cross-sectional Circular Runout)

Cylindricity (Cylindricity)

Perpendicularity (Perpendicularity)

Least Squares Cylinder (LSqCylinder (Move)

 

 

 

1) Virtual Clearance

Inputs:

1.At least two planar, parallel and approximately circular point sets.

•Click the "More" button and enter the number of point sets in the "Constant" box.

•For each constant enter the number of points in the point set.

•Enter the points in each point set consecutively. Since there may be more than two point sets the division between "Group 1" and "Group 2" can be ignored. The point sets can be entered in either box.

•If the total number of points entered does not equal the expected number as indicated by the constants, the function will write an error to the log file.

2.A vector normal to the three planes.

Processing:

1.Compute the least squares (LS) circle for each cross section.
2.Approximate each cross section as a circle concentric with the LS circle, whose radius is equal to the distance from the center to the closest point of the cross section.

Output:

The measurement will be the diameter of the largest circle that can be inscribed in the overlap of the three cross sectional circles, as viewed in the direction of the normal vector.

 

 

2) Cross-sectional Circularity

Inputs:

1.A planar and approximately circular point set.
2.A vector normal to the plane.

Processing:

Compute the LS circle of the point set.

Output:

The measurement will be the difference of the maximum and minimum distances from the points in the cross section to the center of the LS circle.

 

 

3) Cross-sectional Circular Runout

Inputs:

1.An approximately cylindrical point set.

•Enter this point set in "Group 1."

2.A planar and approximately circular point set.

•Enter this point set in "Group 2."

Processing:

Compute the LS cylinder of the cylindrical point set and uses its axis as the datum.

Output:

The measurement will be the difference of the maximum and minimum distances from the points on the second feature to the datum axis.

 

 

4) Cylindricity

Inputs:

An approximately cylindrical point set.

Processing:

Compute the LS cylinder of the point set.

1. The least squares cylinder of the data set is computed.

2. The maximum and minimum envelopes are computed and the difference is reported.

 

Output:

The measurement will be the difference of the maximum and minimum distances from the points to the axis of the LS cylinder.

 

 

5) Perpendicularity

Inputs:

1. An approximately planar point set.

•Enter this point set in "Group 1."

2. An approximately cylindrical point set.

•Enter this point set in "Group 2."

Note: Either point set may be regarded as the datum feature.

Processing:

1. Compute the LS plane of the first point set.

2. Compute the LS cylinder of the second point set.

Output:

The measurement will be the angle (in degrees) between the normal vector of the LS plane and the axis of the LS cylinder.

 

 

6)Least Squares Cylinder Move

Inputs:

1.Two object points
2.An approximately cylindrical target point set

Processing:

1.Compute the LS cylinder of the target point set.
2.Project the two object points onto the LS cylinder axis.
3.Define a two point move that moves the two object points onto their projections on the axis.

Output:

The two point move will be applied to the object.