Manufacturing Deviations Research Articles

省エネ対応ばらつき対策偏向ヨークと偏向パワーの高精度計算法

We quantitatively analyzed the real cause of convergence fluctuations in power-saved rectangular cone deflection yokes, and we found that minimizing the manufacturing deviations of the ferrite core lessened the convergence fluctuations. By using magnetic field simulations of several types of deflection yokes in addition to the above analysis, we solved the problems of power saving and convergence fluctuations. Additionally, we proved that this idea could be applied to large sizes and wide-angle deflection yokes for TV. Furthermore, we established an accurate power estimation method that is essential to the power-saving system.

Thermal hydraulic calculation of the HTR-10 for the initial and equilibrium core

The thermal hydraulic calculations of the 10 MW high temperature gas-cooled-test module (HTR-10) are among the most important indications to judge the reactor performance under design conditions. The power distribution, the temperature distribution and the flow distribution of the HTR-10 are calculated for initial and equilibrium core in this paper. The temperature distribution includes the temperature parameters of fuel elements, the helium coolant and the main components in the reactor. In the temperature calculation of fuel elements, several uncertain factors are considered carefully, including non-uniform burnup, power distribution deviation, manufacture deviation of fuel elements, graphite balls mixed with fuel balls in the core, calculation deviation of heat transfer and so on. In the flow distribution calculation, the conservative pebble bed core flow value is selected. The results show that the maximum fuel temperature is much lower than the limitation and the flow distribution can meet the cooling requirement in the reactor core.

Assessment on Tolerance Representation and Tolerance Analysis in Assemblies

Due to the difficulty of modeling the manufacturing deviations reliably, the existing geometric models, to date, have only con sidered the exact description of parts and assemblies. Yet, the tolerance representation and propagation issues in assemblies are crucial to answer parallel design of product and process queries. Many formal and informal methods have been developed. However, most proved special cases of the ANSI Y14.5M-82 specification standard. Also, the descriptions provided in actual solid and feature based de sign modelers are inadequate to ascertain a clear taxonomy of tolerance specifications, neither do they help address the assembly toler ance analysis and/or synthesis issues. The paper purposes to discuss the tolerance representation schemes as well as their underlying philosophies. Then, because toler ance analysis and tolerance synthesis in assemblies are required, among other tasks, to assign functional tolerances, measure the manufacturability and the interchangeability of parts in assemblies, ease tolerance inspection and evaluate costs of alternative assembly sequences, we shall assess deterministic and statistical methods.

Methods for evaluation of systematic geometric deviations in machined parts and their relationships to process variables

Increasing demands for precision-machined parts put a greater emphasis on achieving a better understanding of the relationships between manufacturing process variables and deviations from perfect geometric forms. To achieve this understanding, it is important to have high-quality metrology data on part features, which (in some sense) span the range of variability in form for the process under study. The problem is complex, involving the machine tool itself, materials, fixtures, cutters, feeds, speeds, and many other factors. In this report, a method is introduced that can identify key deviations from perfect form and can elucidate their dependence on some of the factors enumerated above. This work presents two useful models for form errors of cylindrical features and develops special cases of those models to suit specific requirements. One is an analytical model based on Chebyshev polynomials to model the axial errors and Fourier series to model angular dependencies. The second modeling approach uses the techniques of principal component analysis to extract a basis set of characteristic shapes directly from the measurement data. This report includes a full development of the mathematical basis for the analysis and concludes with some application examples.

Unbalanced Hydraulic Forces Caused by Geometrical Manufacturing Deviations of Centrifugal Impellers

When an impeller has geometrical manufacturing deviations, synchronous vibration occurs from an unbalanced hydraulic force rotating with the impeller. This phenomenon is termed “Hydraulic unbalance.” In this study, experiments and analyses were carried out to study the hydraulic unbalance. We made several model impellers with intentional “manufacturing deviations”: in vane angle, vane pitch, and with eccentricity. Hydraulic forces were estimated from the rotor vibrations. The results of the experiments showed that the magnitude of the hydraulic force increased as the increase of the extent of manufacturing deviations. It was also shown that the amplitude and the phase of the vibration due to the unbalanced hydraulic force depend on the flow rate. This character of the unbalanced hydraulic force is quite different from that of the mass unbalance force, which is independent of the flow rate. A two-dimensional inviscid flow analysis was carried out to clarify the characteristic of the unbalanced hydraulic force. It was found that the hydraulic force can be divided into three components which are constant, linear and parabolic function of the flow rate. Applications of the present results show that the “hydraulic unbalance” of a high-speed pump impeller manufactured within a geometrical tolerance recommended by a typical standard can be larger than the ordinary “mechanical unbalance.” It was thus shown that the hydraulic unbalance is one of the important factors in the balancing of high-speed pump rotors.

Piezoelectric ceramic filters using the edge‐mode vibration

AbstractFor a conventional MF‐band piezoelectric filter, the contour vibration has mainly been used in which the whole of the vibrator body vibrates, and the vibrator is supported at its nodal point by a spring or a soldered wire. This degrades the characteristics of the filters, widens their manufacturing deviations, and limits their reliability and miniaturization. This paper proposes a new type of piezoelectric ceramic filter for the MF‐band using the edge‐mode vibration. This type of filter has a simple shape and a small size, and can be supported by vibration‐absorptive means such as a trapped‐energy type vibrator. The three‐terminal single‐mode filter is presented in which the electrode is divided with a gap into two parts to be used for the input and output. The relationship between the width of the gap and the fractional bandwidth of the filter is calculated theoretically, and the upper limit of its bandwidth is given. By using Pb(Zr, Ti)O3 pieaoelectric ceramics, two types of 455‐kHz filters having the 3‐dB fractional bandwidth of 1.3% and 1.6%, respectively, have been produced experimentally. By connecting 3 or 4 units of either type of the filters in cascade, a filter having the out‐of‐band attenuation greater than 50 dB over the wide frequency range up to ten times the center frequency has been produced successfully. To widen the bandwidth of the edge‐mode piezoelectric filter, the double‐mode filter consisting of two acoustically coupled resonators is also proposed. Experimental results confirm the practical usefulness of this type of filter.

Measuring the flank geometry of bevel gears on a multiple-coordinate measuring machine

Using the multiple-coordinate measuring techfnique and appropriate, problem-oriented software it is possible to measure manufacturing deviations on bevel gears with great precision. Additionally, the influence of fine machining and heat treating processes as well as the wear performance can be determined from comparative measurements. In contrast to the conventional bevel-gear examination, these measurements allow a detailed analysis of the toothing geometry to be made. This provides the prerequisites for methodically influencing the stting data of the bevel-gear cutting machine, with a view to obtaining the desired flank geometry.