Measurement of The Cycloidal Drive Sleeves and Pins

In the paper, an issue of CMM measurement strategy of the sleeves and pins designed for wear tests in the cycloidal drive. The measurement strategy was proposed, based on initial out-of-roundness measurement in scanning mode. Proposed approach ensured that the pin was measured along its entire 40 mm length with only small area of fixation ca. 5 mm left out, and all probing points for cylindricity deviation assessment were collected in one fixation. It was demonstrated that the cylindricity and roundness measurement results based on 8, 16 and 48 probing points provided sufficient data for further wear analysis. In some cases, the circles calculated from 4 points gave additional insights allowing to accept the part that otherwise might be possibly rejected.

Three-Probe Error Separation with Chromatic Confocal Sensors for Roundness Measurement

In this study, three-probe error separation was developed with three chromatic confocal displacement sensors for roundness measurement. Here, the harmonic suppression is discussed first to set suitable orientation angles among three sensors. Monte Carlo simulation is utilized to test the error separation and optimize the orientation angles and off-axial distance. The experimental setup is established using chromatic confocal sensors with a precise rotary platform. The experimental results show that the measured roundness with an orientation-angle combination of (0°, 90.1°, and 178.6°) is much better than that of another nonoptimal selection (0°, 90.4°, and 177.4°). The roundness error is only 0.7% between the proposed measurement system and an expensive ultraprecision roundness meter. Furthermore, it is proven that the eccentricity distance should be decreased as small as possible to improve the measurement accuracy. In sum, this paper proposes a feasible method for roundness measurement with reliable simulations, easily integrated sensors, and an ordinary precision rotary platform.

Rotation Accuracy Analysis of Aerostatic Spindle Considering Shaft’s Roundness and Cylindricity

The rotation accuracy of the aerostatic spindle can easily be affected by shaft shape errors due to the small gas film clearance. Thus, the main shaft shape errors with the largest scale—that is, the roundness and cylindricity errors—are studied in this paper, and a dynamic mathematical model is established with the consideration of the roundness, cylindricity errors, and spindle speed. In order to construct the shaft model, the discrete coefficient index of the shaft radius based on roundness measurement data are proposed. Then, the simulation calculations are conducted based on the measured cylindricity data and the constructed shaft model. The calculation results are compared with the spindle rotation accuracy measured using the spindle error analyzer. The results show that the shaft with a low discrete coefficient is subjected to less unbalanced force and smaller rotation errors, as obtained by the experiment.

Improvement of a Stitching Operation in the Stitching Linear-Scan Method for Measurement of Cylinders in a Small Dimension

Attempts are made in this paper to improve the quality of the stitching between adjacent arc-profiles in the stitching linear-scan method for the roundness measurement of a cylinder in a small dimension. The data in the edge region of an arc-profile, which could be influenced by the pressure angle of the measurement probe of a linear-scan stylus profiler, are eliminated in the stitching process to improve the quality of stitching. The effectiveness of the elimination of the edge region of an arc-profile is evaluated by employing the cross-correlation coefficient of two adjacent arc-profiles as an evaluation index. Furthermore, a modification is made to the experimental setup to reduce the misalignment of a workpiece along its axial direction with respect to the scanning probe. Experiments are carried out by using the modified setup to demonstrate the feasibility of the stitching linear-scan method for the roundness measurement of a small cylinder, which is difficult to measure by the conventional rotary-scan method.

Gravel roundness quantitative analysis for sedimentary microfacies of fan delta deposition, Baikouquan Formation, Mahu Depression, Northwestern China

Gravel roundness is one of the simple but crucial parameters in particle shape, which is related to the transportation and deposition of sediments. Based on the digital images of underground drilling cores, this study attempted to characterize and distinguish sedimentary microfacies by quantitatively test gravel roundness trends in the fan delta deposition of the Early Triassic Baikouquan Formation in Mahu Depression, Juggar Basin of China. By the new proposed de-flat roundness measurement, two major parameters are recorded to manifest the rounding degree, which is de-flat roundness value (Rdn) and the corresponding variance value. In the case study, roundness characteristics of four microfacies in the fan delta deposits are displayed and compared. Results show that braided channels and submerged distributary channels are characterized by better rounding (Rdn 0.379 to 0.603, and 0.366 to 0.591, respectively) and smaller variance, while debris flow and submerged debris flow are characterized by worse rounding (Rdn 0.333 to 0.405 and 0.256 to 0.391, respectively) and larger variance. In vertical of the roundness curves, channels deposits and gravity flow deposits reveal notable distinction in terms of the numeric ranges, fluctuation amplitude, and fluctuate frequency. It is interpreted to represent the different sedimentary processes during particle transport and deposit, as well as new clastics mixed in from other sources. Therefore, roundness could be a useful complementary data to provide quantitative sedimentological evidence and theoretical support for the study of coarse clastic depositional system.