scholarly journals The method for identifying of inaccuracy causes in turning machining center by processing a sample part

2021 ◽  
pp. 24-29
Author(s):  
D. A. Blokhin ◽  
◽  
A. G. Koltsov ◽  
Yu. A. Blokhina ◽  
M. M. Lakman ◽  
...  
Keyword(s):  
Test Procedure ◽  
Complete Information ◽  
Processing Method ◽  
Machine Errors ◽  
Machining Center ◽  
Control Surfaces ◽  
Accumulated Error ◽  
Screw Pitch

The article discusses the issues of the processing method of a turning machining center for processing the accuracy of processing a sample part. The model of sample part with the smallest possible control surfaces processed by various shaping methods has been developed to detect the amount of machine errors, such as the accumulated error of the screw pitch, or the axial non-perpendicularity, or the misalignment of the X and Y drives. This allows you to get more complete information of the equipment accuracy. A test procedure is presented according to the results of measuring each surface of the sample part

Study on the Processing and Simulation of End-Gear Based on CNC Theory

2014 ◽  
Vol 608-609 ◽  
pp. 77-80
Author(s):  
Li Mei Wang
Keyword(s):  
High Efficiency ◽  
Gear Wheel ◽  
Nc Machining ◽  
Processing Method ◽  
Bevel Gear ◽  
Hypoid Gear ◽  
Face Gear ◽  
Hypoid Gears ◽  
Machining Center ◽  
The Mathematical Model

Based on NC machining principle of hypoid gears and NC machining with high efficiency quality, This paper discusses the feasibility of the hypoid gear processing, establishes the mathematical model of face gear wheel hypoid milling machining adjustment, that will be take the basic data into vertical machining center machine tool. Through analyze the principle of the oscillating tooth face gear transmission, and compared the structure differences between face gear and bevel gear, and the realization processing method of face gear is discussed by improving the bevel gear shaper.

Real-time Compensation for Time-variant Volumetric Errors on a Machining Center

1993 ◽  
Vol 115 (4) ◽  
pp. 472-479 ◽  
Author(s):  
J. S. Chen ◽  
J. X. Yuan ◽  
J. Ni ◽  
S. M. Wu
Keyword(s):  
Real Time ◽  
Computer Control ◽  
Thermal Error ◽  
Coordinate Measuring Machine ◽  
Error Components ◽  
Machine Errors ◽  
Machining Center ◽  
Volumetric Errors ◽  
Measuring Machine ◽  
Cnc Controller

An error compensation system has been developed to enhance the time-variant volumetric accuracy of a 3-axis machining center by correcting the existing machine errors through sensing, metrology, and computer control techniques. A general methodology has been developed to synthesize both the geometric and thermal errors of machines into a time-variant volumetric error model. Instead of the well-known 21 geometric error components, 32 machine linkage errors are formulated as a 4D error field including the space domain and the time domain. Different types of models are proposed for different kinds of thermal error components. A compensation controller based on an IBM/PC has been linked with a CNC controller to compensate for machine errors in real time. This scheme has been implemented on a horizontal machining center and has been shown, using metrology instruments, to improve the machine accuracy by an order of magnitude. A cut workpiece inspected using a coordinate measuring machine (CMM) has also shown that dimension errors have been reduced from 92.4 μm to 18.9 μm in a dimension of 404 × 310 mm2 and the depth difference of milled surfaces has been reduced from 196 μm to 8 μm.

Coupled Vibration Modal Analysis of Synchronous Dual Ball Screw Feeding System

2013 ◽  
Vol 433-435 ◽  
pp. 8-11
Author(s):  
Zhi Yuan Rui ◽  
Yu Lin Tang ◽  
Rui Cheng Feng ◽  
Yong Li ◽  
Yan Rui Zuo
Keyword(s):  
Vibration Mode ◽  
Ball Screw ◽  
Feeding System ◽  
Coupled Vibration ◽  
Ansys Analysis ◽  
Machining Center ◽  
Modal Coupling ◽  
Coupling Characteristics ◽  
Vibration Modal ◽  
Screw Pitch

With the Synchronous Dual Ball Screw Feeding System used in a Milling-Turning compound machining center as the research object. For study the ball screw vibration modal, which using Lagrange established the dynamics equation and using the Lizs series expansion analyzing its various order modal coupling characteristics. Meanwhile using the ANSYS analysis to get the first three order vibration mode diagram and calculate the frequency corresponding to the critical speed for each rank. Through the analysis found that the screw pitch determine the modal coupling axial and corner, the workbench position and load quality changes, the screw vibration frequency also changes. Provide theoretical analysis for the analysis of dynamic characteristics of the next step.

Low-temperature Mo-catalyzed growth of crystalline Si3N4 by CVD

1993 ◽  
Vol 51 ◽  
pp. 918-919
Author(s):  
K.L. More ◽  
R.A. Lowden ◽  
T.M. Besmann
Keyword(s):  
Vapor Deposition ◽  
Hot Isostatic Pressing ◽  
Chemical Vapor ◽  
Processing Method ◽  
Crystalline Material ◽  
Structural Ceramic ◽  
Alternative Processing ◽  
Strong Candidate ◽  
Hot Pressing Sintering ◽  
Processing Techniques

Silicon nitride possesses an attractive combination of thermo-mechanical properties which makes it a strong candidate material for many structural ceramic applications. Unfortunately, many of the conventional processing techniques used to produce Si3N4, such as hot-pressing, sintering, and hot-isostatic pressing, utilize significant amounts of densification aids (Y2O3, Al2O3, MgO, etc.) which ultimately lowers the utilization temperature to well below that of pure Si3N4 and also decreases the oxidation resistance. Chemical vapor deposition (CVD) is an alternative processing method for producing pure Si3N4. However, deposits made at temperatures less than ~1200°C are usually amorphous and at slightly higher temperatures, the deposition of crystalline material requires extremely low deposition rates (~5 μm/h). Niihara and Hirai deposited crystalline α-Si3N4 at 1400°C at a deposition rate of ~730 μm/h. Hirai and Hayashi successfully lowered the CVD temperature for the growth of crystalline Si3N4 by adding TiCl4 vapor to the SiCl4, NH3, and H2 reactants. This resulted in the growth of α-Si3N4 with small amounts of TiN at temperatures as low as 1250°C.

Benefits from Computerized Adaptive Testing as Seen in Simulation Studies

1999 ◽  
Vol 15 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Lutz F. Hornke
Keyword(s):  
Measurement Error ◽  
Computerized Adaptive Testing ◽  
Test Procedure ◽  
Adaptive Testing ◽  
Parameter Estimates ◽  
Simulation Studies ◽  
Computerized Adaptive Test ◽  
Item Banks ◽  
Item Parameters ◽  
General Reliability

Summary: Item parameters for several hundreds of items were estimated based on empirical data from several thousands of subjects. The logistic one-parameter (1PL) and two-parameter (2PL) model estimates were evaluated. However, model fit showed that only a subset of items complied sufficiently, so that the remaining ones were assembled in well-fitting item banks. In several simulation studies 5000 simulated responses were generated in accordance with a computerized adaptive test procedure along with person parameters. A general reliability of .80 or a standard error of measurement of .44 was used as a stopping rule to end CAT testing. We also recorded how often each item was used by all simulees. Person-parameter estimates based on CAT correlated higher than .90 with true values simulated. For all 1PL fitting item banks most simulees used more than 20 items but less than 30 items to reach the pre-set level of measurement error. However, testing based on item banks that complied to the 2PL revealed that, on average, only 10 items were sufficient to end testing at the same measurement error level. Both clearly demonstrate the precision and economy of computerized adaptive testing. Empirical evaluations from everyday uses will show whether these trends will hold up in practice. If so, CAT will become possible and reasonable with some 150 well-calibrated 2PL items.

Evaluating the Validity of a Bayesian Program for Predicting Stage in Hodgkin’s Disease

1981 ◽  
Vol 20 (03) ◽  
pp. 174-178 ◽  
Author(s):  
A. I. Barnett ◽  
J. Cynthia ◽  
F. Jane ◽  
Nancy Gutensohn ◽  
B. Davies
Keyword(s):  
New England ◽  
Hodgkin's Disease ◽  
Bayesian Model ◽  
Medical Center ◽  
Hodgkin’S Disease ◽  
Test Procedure ◽  
Disease Patient ◽  
Probabilistic Information ◽  
Probabilistic Forecasts ◽  
England Medical

A Bayesian model that provides probabilistic information about the spread of malignancy in a Hodgkin’s disease patient has been developed at the Tufts New England Medical Center. In assessing the model’s reliability, it seemed important to use it to make predictions about patients other than those relevant to its construction. The accuracy of these predictions could then be tested statistically. This paper describes such a test, based on 243 Hodgkin’s disease patients of known pathologic stage. The results obtained were supportive of the model, and the test procedure might interest those wishing to determine whether the imperfections that attend any attempt to make probabilistic forecasts have gravely damaged their accuracy.

Reliability of Laboratory Tests for the Control of Oral Anticoagulation

1974 ◽  
Vol 32 (02/03) ◽  
pp. 483-491
Author(s):  
E. A Loeliger ◽  
M. J Boekhout-Mussert ◽  
L. P van Halem-Visser ◽  
J. D. E Habbema ◽  
H de Jonge
Keyword(s):  
Human Brain ◽  
Laboratory Tests ◽  
Test Procedure ◽  
Rabbit Brain ◽  
Normal Range ◽  
Test Procedures ◽  
Discrimination Power ◽  
Power Of The Test ◽  
Assay Procedure ◽  
Low Sensitivity

SummaryThe present study concerned the reproducibility of the so-called prothrombin time as assessed with a series of more commonly used modifications of the Quick’s onestage assay procedure, i.e. the British comparative reagent, homemade human brain thromboplastin, Simplastin, Simplastin A, and Thrombotest. All five procedures were tested manually on pooled lyophilized normal and patients’ plasmas. In addition, Simplastin A and Thrombotest were investigated semiautomatically on individual freshly prepared patients’ plasmas. From the results obtained, the following conclusions may be drawn :The reproducibility of results obtained with manual reading on lyophilized plasmas is satisfactory for all five test procedures. For Simplastin, the reproducibility of values in the range of insufficient anticoagulation is relatively low due to the low discrimination power of the test procedure in the near-normal range (so-called low sensitivity of rabbit brain thromboplastins). The reproducibility of Thrombotest excels as a consequence of its particularly easily discerned coagulation endpoint.The reproducibility of Thrombotest, when tested on freshly prepared plasmas using Schnitger’s semiautomatic coagulometer (a fibrinometer-liJce apparatus), is no longer superior to that of Simplastin A.The constant of proportionality between the coagulation times formed with Simplastin A and Thrombotest was estimated at 0.64.Reconstituted Thrombotest is stable for 24 hours when stored at 4° C, whereas reconstituted Simplastin A is not.The Simplastin A method and Thrombotest seem to be equally sensitive to “activation” of blood coagulation upon storage.

Hubungan Antara Anemia dan Kebiasaan Merokok pada Ibu Hamil dengan Kejadian BBLR di Rumah Sakit Umum Pusat Dr. Mohammad Hoesin Palembang Tahun 2016

2018 ◽  
Vol 1 (2) ◽  
pp. 89-94
Author(s):  
Intan Sari
Keyword(s):  
Birth Weight ◽  
Low Birth Weight ◽  
General Hospital ◽  
Smoking Habit ◽  
Complete Information ◽  
Developed Countries ◽  
Statistical Test ◽  
Survey Method ◽  
Bivariate Analysis ◽  
Cross Sectional

Low Birth Weight (LBW) is an infant born with a birth weight of less than 2500 grams regardless of gestation. Birth weight is the weight of the baby weighed in 1 hour after birth. (Depkes RI, 2009). Based on WHO and UNICEF data, in 2013 about 222 million babies were born in the world, of which 16% were born with low birth weight. The percentage of LBW in developing countries is 16.5% twice that of developed countries (7%) (Scholar Unand, 2014). The purpose of this study was to determine whether there is a relationship between anemia and Smoking Habit in Pregnant Women with LBW occurrence in General Hospital Dr. Mohammad Hoesin Palembang Year 2016. This research use analytical survey method with cross sectional approach. The population in this study were all mothers who gave birth monthly in Midwifery Installation of Dr. General Hospital Mohammad Hoesin Palembang in 2016 as many as 315 respondents. The sample of this research is some of mothers who give birth enough month in Midwifery Installation of Dr. General Hospital Mohammad Hoesin Palembang Year 2016 as many as 315 respondents. ". From the results of bivariate analysis of anemic respondents with the occurrence of LBW obtained statistical test X2 count = 23.22 which means there is a significant relationship between anemia with the incidence of BBLR. Respondents smoking with the occurrence of LBWR obtained statistical test X2 count = 41.20 which means there is a relationship Meaningful between smoking and LBW incidence. From the results of this study is expected that this research can be a reference material and is a complete information and useful for the development of knowledge about LBW.

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