Description

The present day conditions of a harsh competition, a products and services internationalised exchange raises vital problems concerning to the economical assurance of quality. In these conditions the theoretical model form and aspect transmitting on the a piece (product) present different difficulties for those solution are necessary complex technologies and tool machines, in especially, in the case of solid materials at which the field of the geometrical dimensions measurements covers 60-90%.
The objectification and automation of the quality monitoring, decrease of dispersion for mechanical processes simultaneously with the increase of the precision for dimensions and geometric forms, the execution prevention of the unsuitable pieces were made that the using of the coordinate measuring systems should be imposed by universality, precision, productivity especially in the case of complex pieces.
It is presented the dates of methodology for establish the measurement strategy by coordinate machine for a complex piece.
By representing files of the base elements under CAD are geometrically modeled the structure of a coordinate measuring machine, finally resulting the representation from figure1, which is imported in 3Dstudio, then.
The whole modeling program is open permitting the intervention on data for the modification after wish of some constructive values for the model.
It is considered a complex piece ROTOR type presented in the figure 2.
For the specific element PALETTE, the figure 3 from frame of this rotor of turbine are established the coordinates of the characteristic points.
Usually, the coordinates of the characteristics points are given by the designer in the measure case of an existent piece which is verified and for which is made a special measuring strategy.

SOLUTION

In case of considered piece, the values of coordinates are presented in the list with nominal coordinates of the palette characteristic points.
It is imposed the appreciation of the coordinates for a sufficient number situated suitable to correctly define form and dimensions of element.
The characteristic points were established 14 in a row on the internal face of palette named intrados, in the plane of the inferior face (inferior intrados), respectively, in the plane of superior face (superior intrados) and on the exterior face of palette named extrados, in the plane of the inferior face (inferior extrados) respectively, in the plane of superior face (superior extrados).
The measuring strategy imposes the displacement of gauge in the position specified by the coordinates of the characteristic points.
These coordinates are transposed in absolute coordinate (the machine coordinate), thus, it is taken into account to the centered position of piece on the machine table.
The measuring process of a palette of rotor was been simulated on computer using animation files in 3Dstudio.
With base elements previously defined (the coordinate measuring machine with portal and rotor with palettes set up on the machine table) are established joints between objects also, and, suborders type ”parent-child” with condition that the gauge should be moved on a trajectory corresponding to the characteristic points of the controlled element (the palette).
This imposes the establishment of trajectory, which consists of the broken line obtained by the joining of points, which will be measured in this case.
The model is taken in the Key framer, which permits the establishment of the displacement parameters of the defined elements (joints and suborder of objects, number of frames exposed on second, total number of images, time of exposition for a frame, total period of animation, fix or mobile position of video camera, light sources, etc.).
In the figures 4 a, b, c is presented three positions of motion.
The definition of the kinematical parameters is realized in the inverse kinematical module (IK-Inverse Kinematics), which permit the automatic obtaining of „kinematical skeleton” of the realized model also, and the defining of the joints.
After the pre-visualization of displacements is saved the model and animation and, is returned in the Key framer. It is repeated and, finally, it is obtained the movie, which represents the simulation of the analyzed measuring process.

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