New Method Based on Improved Double Ball Bar for Measuring Geometric Motion Errors of Coordinate Measuring Machine

2018 ◽  
Vol 12 (2) ◽  
pp. 199-205
Author(s):  
Ping Yang ◽  
◽  
Yue Wu ◽  
Hui Yu ◽  
Yinbiao Guo
Keyword(s):  
Rotation Angle ◽  
Coordinate Measuring Machine ◽  
Influential Factors ◽  
New Method ◽  
Separation Algorithm ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Measuring Machine ◽  
The Difference ◽  
Geometric Motion

In this paper, an optimized method of measuring the geometric motion errors of a coordinate measuring machine (CMM) is proposed. The method is based on an improved double ball bar (DBB) that acquires the motion and link errors of the CMM and its actual rotation angles through simultaneous circular tests. The improved DBB has embedded a ring encoder system to the bottom of a commercial DBB on an auxiliary platform. In addition, an improved motion and link error separation algorithm is established by considering the difference angle Δθ between the actual rotation angle and the theoretical rotation angle of the DBB. Both influential factors of the center offset of the DBB and Δθ are discussed through simulations. When geometric motion errors are compensated for and measured on a 400 mm × 400 mm × 150 mm CMM, the standard deviations of the roundness errors decrease to 1.9 μm and 1.5 μm on the XY and ZX planes, respectively.

A New Method of CMM Inspect Path Planning for Precision Generalized Helicoid

2010 ◽  
Vol 455 ◽  
pp. 458-461
Author(s):  
Wei Min Pan ◽  
Yong Jian Yu ◽  
J.S. Li ◽  
F. Xu
Keyword(s):  
Path Planning ◽  
Aerial Part ◽  
Power Transmission ◽  
Coordinate Measuring Machine ◽  
Measuring Method ◽  
New Method ◽  
Measuring Process ◽  
Measuring Machine

The helical surfaces are widely applied to both power transmission and fluid compression or pumping. Helicoid is measured by digitized measurement with the coordinate measuring machine (CMM) in this paper. A numerical measuring method which is different from traditional measuring method for Helicoid is given. The Measuring process is illustrated in detail. At the same time, this method is proved effectiveness through a practical measuring example of an aerial part.

An exact method for the sphericity measurement of soccer balls

2003 ◽  
Vol 217 (5) ◽  
pp. 715-719 ◽  
Author(s):  
P J Neilson ◽  
R Jones
Keyword(s):  
Three Dimensional ◽  
Computer Software ◽  
Coordinate Measuring Machine ◽  
Current Method ◽  
New Method ◽  
Ball Surface ◽  
Ball Diameter ◽  
Sphere Approximation ◽  
Measuring Machine ◽  
A New Technique

The most popular games in the world are ball sports. Generally, ball properties such as weight, circumference and sphericity are specified in the rules and determine the ball quality. The current method of sphericity measurement employed by the Federation International Football Association (FIFA) is to measure the ball diameter at 16 points and then calculate the mean average. The sphericity of the ball is inferred from the diametric measurements. Unfortunately, diameter measurement does not guarantee sphericity, and a new technique has been developed to measure ball sphericity using a coordinate measuring machine (CMM). In this method a representative sample of the ball surface is probed/measured to give three-dimensional coordinates of defined points, nominally the ball panel centres. Computer software is then used to fit a least-squares sphere approximation to the ball data, giving a unique value for ball sphericity. Measurements were taken of six different brand type balls, with a sample of four balls of each brand; all balls were inflated to the same pressure. The results show that the new method of sphericity measurement suggested here gives a unique assessment of sphericity. The errors obtained from the new method are such that the FIFA error specification may need reconsideration.

Study on Measuring Perpendicularity Based-On Non-Diffracting Beam as the References

2012 ◽  
Vol 586 ◽  
pp. 349-355
Author(s):  
Xin Bao Zhang ◽  
Kun Zhang ◽  
Hong Lu
Keyword(s):  
Coordinate Measuring Machine ◽  
Position Error ◽  
New Method ◽  
Straight Line ◽  
Pentagonal Prism ◽  
Measuring Machine ◽  
Working Distance

A new method for measuring perpendicularity is developed in this paper, in which the non-diffracting beam that illuminates a pentagonal prism to produce the vertical reference is used as the straight-line reference and CCD is used as the sensor to gauge the position error to the references. Three evaluation algorithms of the perpendicularity error are also given in the paper. And furthermore, perpendicularity of a Coordinate Measuring Machine was measured by this method, which is easy to be operated. The results and analysis indicate that its working distance can be more than 15m while the precision can be less than±5μm/m.

scholarly journals In Vitro Comparative Evaluation of Different Types of Impression Trays and Impression Materials on the Accuracy of Open Tray Implant Impressions: A Pilot Study

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Sonam Gupta ◽  
Aparna Ichalangod Narayan ◽  
Dhanasekar Balakrishnan
Keyword(s):  
Reference Model ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Impression Material ◽  
Impression Materials ◽  
Significant Difference ◽  
Different Types ◽  
Measuring Machine ◽  
The Difference

Purpose. For a precise fit of multiple implant framework, having an accurate definitive cast is imperative. The present study evaluated dimensional accuracy of master casts obtained using different impression trays and materials with open tray impression technique.Materials and Methods. A machined aluminum reference model with four parallel implant analogues was fabricated. Forty implant level impressions were made. Eight groups (n=5) were tested using impression materials (polyether and vinylsiloxanether) and four types of impression trays, two being custom (self-cure acrylic and light cure acrylic) and two being stock (plastic and metal). The interimplant distances were measured on master casts using a coordinate measuring machine. The collected data was compared with a standard reference model and was statistically analyzed using two-way ANOVA.Results. Statistically significant difference (p<0.05) was found between the two impression materials. However, the difference seen was small (36 μm) irrespective of the tray type used. No significant difference (p>0.05) was observed between varied stock and custom trays.Conclusions. The polyether impression material proved to be more accurate than vinylsiloxanether impression material. The rigid nonperforated stock trays, both plastic and metal, could be an alternative for custom trays for multi-implant impressions when used with medium viscosity impression materials.

scholarly journals Comparison of clinical bracket point registration with 3D laser scanner and coordinate measuring machine

2015 ◽  
Vol 20 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Mahtab Nouri ◽  
Arash Farzan ◽  
Ali Reza Akbarzadeh Baghban ◽  
Reza Massudi
Keyword(s):  
Intraclass Correlation ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Coordinate Measuring Machine ◽  
Diagnostic Value ◽  
Mean Difference ◽  
Validity And Reliability ◽  
Measuring Machine ◽  
The Mean ◽  
The Difference

OBJECTIVE: The aim of the present study was to assess the diagnostic value of a laser scanner developed to determine the coordinates of clinical bracket points and to compare with the results of a coordinate measuring machine (CMM). METHODS: This diagnostic experimental study was conducted on maxillary and mandibular orthodontic study casts of 18 adults with normal Class I occlusion. First, the coordinates of the bracket points were measured on all casts by a CMM. Then, the three-dimensional coordinates (X, Y, Z) of the bracket points were measured on the same casts by a 3D laser scanner designed at Shahid Beheshti University, Tehran, Iran. The validity and reliability of each system were assessed by means of intraclass correlation coefficient (ICC) and Dahlberg's formula. RESULTS: The difference between the mean dimension and the actual value for the CMM was 0.0066 mm. (95% CI: 69.98340, 69.99140). The mean difference for the laser scanner was 0.107 ± 0.133 mm (95% CI: -0.002, 0.24). In each method, differences were not significant. The ICC comparing the two methods was 0.998 for the X coordinate, and 0.996 for the Y coordinate; the mean difference for coordinates recorded in the entire arch and for each tooth was 0.616 mm. CONCLUSION: The accuracy of clinical bracket point coordinates measured by the laser scanner was equal to that of CMM. The mean difference in measurements was within the range of operator errors.

The Research on the Zero-Tooth-Difference Internal Gear Measuring Method

2012 ◽  
Vol 189 ◽  
pp. 388-392
Author(s):  
Yu Lan Wei ◽  
Bing Li ◽  
Ying Ying Fan ◽  
Meng Dan Jin
Keyword(s):  
Human Factors ◽  
Coordinate Measuring Machine ◽  
Measuring Method ◽  
Tooth Profile ◽  
Profile Curve ◽  
Theoretic Analysis ◽  
On Line ◽  
Measuring Machine ◽  
The Difference ◽  
Internal Gear

A variable gear measuring method was put forward in order to define the error of eccentricity of the zero-tooth-difference internal gear, which was based on the three-coordinate measuring machine. This method can scan the coordinate of tooth profile automatically and fleetly, then by calculating the difference of the tooth profile curve between the theory and reality, and achieving the measure on line about geared ring radial runout to define the error of eccentricity. The results of this experiment and theoretic analysis showed that the method which was putted forward has many advantages, like the density of sampling is big, the calculation is simple, the measure is accurate, and the human factors are very little.

scholarly journals Coordinate Measuring Machine Probes Effect during Inner Thread Position Measurement

Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 55
Author(s):  
Ferencz Peti ◽  
Petru Serban
Keyword(s):  
Coordinate Measuring Machine ◽  
New Method ◽  
Coordinate Measuring Machines ◽  
Position Measurement ◽  
Measurement Strategy ◽  
Accuracy Of Measurements ◽  
Measuring Machine

Starting from the idea of improving Coordinate Measuring Machines’ (CMM) measurement strategy for inner thread locations, we developed a new method which increases the accuracy of measurements and takes us closer to the pitch diameter. This article will analyze this new method by testing different touching probes configurations for different thread sizes. The objective is to identify the best probe configuration to be used in the measurements of different inner thread sizes.

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