Pitch Deviation Research Articles

Development of Bevel Gear On-Machine Measurement System Based on Open CNC System

Bevel gear is a complicated curved surface parts, the traditional measuring method of bevel gear is by three coordinates measuring instrument for related parameters measurement and there are problems such as reload, high cost and waste of time. In this paper, development of Bevel gear on-machine measurement system based on open CNC system so that the manufacturing and measuring of bevel gear on the same machine tools. This article mainly has studied on structure and function of the system, analyzed the method of pitch deviation and the tooth surface error of the bevel gear and developed bevel gear on-machine measurement system by combining the method of MATLAB with VC++ mixed programming.

Compensation method for the alignment angle error in pitch deviation measurement

When measuring the tooth flank of an involute helical gear by gear measuring center (GMC), the alignment angle error of a gear axis, which was caused by the assembly error and manufacturing error of the GMC, will affect the measurement accuracy of pitch deviation of the gear tooth flank. Based on the model of the involute helical gear and the tooth flank measurement theory, a method is proposed to compensate the alignment angle error that is included in the measurement results of pitch deviation, without changing the initial measurement method of the GMC. Simulation experiments are done to verify the compensation method and the results show that after compensation, the alignment angle error of the gear axis included in measurement results of pitch deviation declines significantly, more than 90% of the alignment angle errors are compensated, and the residual alignment angle errors in pitch deviation measurement results are less than 0.1 μm. It shows that the proposed method can improve the measurement accuracy of the GMC when measuring the pitch deviation of involute helical gear.

Development of a gear measuring device using DFRP method

This paper presents the double-flank rack probe (DFRP) method to measure the accuracy relevant to flanks of gear teeth. In DFRP method, both left and right flanks of the gear to be measured are in mesh with a rack probe to measure pitch and profile deviations on the left and right flanks simultaneously. A gear measuring device (GMD) using DFRP method is developed. The evaluation method for pitch and profile deviations, the structure of the measuring system, and the key mechanical parts are introduced. Repeatability experimental results of the device is less than 2μm, and the results compared to the gear measuring machine (GMM) Klingelnberg P26 shows that this device have consistency with GMM and can be used for the measurement of the accuracy relevant to flanks of gear teeth.

Spring-force self-aligned multiball pitch artifact

Gear noise is influenced by pitch deviation of micrometer order, and, therefore, the pitch of gears is inspected in manufacturing processes using measurement instruments. Master gears or artifacts are used to evaluate the accuracy of the pitch measurement instrument, but their accuracy is not sufficiently high and they are not easy to manufacture. In a previous study, the concept of a novel high-precision pitch artifact composed of simple components was proposed for the evaluation of the accuracy of pitch measurement instruments. Simple components, such as balls, cylinders, and planes, can accomplish an accuracy on the order of several tens of nanometers. Therefore, this artifact can be realized with high accuracy. In the present study, we propose a spring-force self-aligned multiball pitch artifact, in which simple components are assembled using spring force. The design of the artifact is discussed, and the artifact is manufactured. Measurement experiments using a coordinate measurement machine and a pitch measurement instrument are carried out, and the proposed pitch artifact is demonstrated to be fundamentally valid for accuracy evaluation.

ホブ切り歯車の単一ピッチ誤差測定の新たな手法（ガウシアンフィルタを通した歯すじ形状測定結果の適用）

Improving quality of hobbed gears must yield high accuracy of ground gears. This can be achieved by measuring hobbed gears accurately. Pitch deviations are most crucial in grinding processes with a worm type grinder. In the preset study, a new measuring method is proposed for single pitch deviations. In this method, measured helix trace data are conditioned with Gaussian Filter to be divided into short- and long-wavelength components. Single pitch deviations are calculated from the long-wavelength components around the center of facewidth. The calculated deviations showed 62.6 % lower variation in iterative measurements.

Vibration Characteristics Analysis of a Spur Gear Rotor System with the Pitch Deviation

Vibration Characteristics Analysis of a Spur Gear Rotor System with the Pitch Deviation

ホブ切り歯車の単一ピッチ誤差測定精度の向上

ホブ切り歯車の単一ピッチ誤差測定精度の向上

Pitch deviation measurement and analysis of curve-face gear pair

The curve-face gear pair is proposed as a new type of gear pair which was put forward in recent years. It can achieve variable ratio transmission of motion and power between the intersection axes. In the matter of the inspection of the pitch deviations of this gear pair, there is no practical possibility for a reliable metrological traceability to national or international measurement standards can be provided. Hence, a new method was proposed in this article, which was based on the CNC gear measuring center, aimed at the gear artefacts processed by the five-axis machining center. With the coordinate data which were obtained by the gear measuring center, the pitch deviations of the gear pair were obtained. In addition, based on the values of the pitch deviations, the angular deviations of curve-face gear pair can be worked out, and the results turn out that the measurement method is feasible.

Influence of the accumulated error in thread pitch on the stress–strain state and cyclic strength of threaded joints

Using the finite element method, the analysis of influence of errors in pitch during the thread production on the behavior of stress distribution in stud–nut joints is performed. The value of maximum local stresses in studs of a threaded joint is shown to substantially depend on errors in thread pitch of a stud and a nut. On the basis of the analyses of stresses and strains under cyclic loading, fatigue curves are plotted for the threaded joints having deviations in thread pitch. It is shown that, with a rational selection of the deviation in pitch, the cyclic strength of threaded joints can be considerably increased. The results of analysis agree satisfactorily with the data of fatigue tests of the M39 × 3 threaded joints.

Rotational Corrections for Stereotactic Radiosurgery (SRS) of Multiple Brain Metastases Treated With Single Isocenter Technique

Rotational Corrections for Stereotactic Radiosurgery (SRS) of Multiple Brain Metastases Treated With Single Isocenter Technique

Differential processing of melodic, rhythmic and simple tone deviations in musicians -an MEG study

Rhythm and melody are two basic characteristics of music. Performing musicians have to pay attention to both, and avoid errors in either aspect of their performance. To investigate the neural processes involved in detecting melodic and rhythmic errors from auditory input we tested musicians on both kinds of deviations in a mismatch negativity (MMN) design. We found that MMN responses to a rhythmic deviation occurred at shorter latencies than MMN responses to a melodic deviation. Beamformer source analysis showed that the melodic deviation activated superior temporal, inferior frontal and superior frontal areas whereas the activation pattern of the rhythmic deviation focused more strongly on inferior and superior parietal areas, in addition to superior temporal cortex. Activation in the supplementary motor area occurred for both types of deviations. We also recorded responses to similar pitch and tempo deviations in a simple, non-musical repetitive tone pattern. In this case, there was no latency difference between the MMNs and cortical activation was smaller and mostly limited to auditory cortex. The results suggest that prediction and error detection of musical stimuli in trained musicians involve a broad cortical network and that rhythmic and melodic errors are processed in partially different cortical streams.

Attentional flexibility and memory capacity in conductors and pianists.

Individuals with high working memory (WM) capacity also tend to have better selective and divided attention. Although both capacities are essential for skilled performance in many areas, evidence for potential training and expertise effects is scarce. We investigated the attentional flexibility of musical conductors by comparing them to equivalently trained pianists. Conductors must focus their attention both on individual instruments and on larger sections of different instruments. We studied students and professionals in both domains to assess the contributions of age and training to these skills. Participants completed WM span tests for auditory and visual (notated) pitches and timing durations, as well as long-term memory tests. In three dichotic attention tasks, they were asked to detect small pitch and timing deviations from two melodic streams presented in baseline (separate streams), selective-attention (concentrating on only one stream), and divided-attention (concentrating on targets in both streams simultaneously) conditions. Conductors were better than pianists in detecting timing deviations in divided attention, and experts detected more targets than students. We found no group differences for WM capacity or for pitch deviations in the attention tasks, even after controlling for the older age of the experts. Musicians' WM spans across multimodal conditions were positively related to selective and divided attention. High-WM participants also had shorter reaction times in selective attention. Taken together, conductors showed higher attentional flexibility in successfully switching between different foci of attention.

Manufacturing method of double-helical gears using CNC machining center

Double-helical gears are usually manufactured using special type of machine tools, such as gear hobbing and shaping machines. In this paper, a manufacturing method of double-helical gears using a CNC machining center instead of the special type of machine tools is proposed. This manufacturing method has the following advantages: (i) the tooth surfaces can be modified arbitrarily, (ii) all we have to do in gear machining is only one machine setting, (iii) the hole and blank diameter and so on except the tooth surface can be also machined, and (iv) the auxiliary apparatus, special type of tools, and special type of machine tools are not needed. For this study, first the tooth profiles of the double-helical gear were modelled using a 3D computer-aided design system and the gear was machined using a CNC machining center based on a computer-aided manufacturing system. Next, the profile deviations, helix deviations, pitch deviations, and surface roughnesses of the manufactured double-helical gears were measured. Afterwards, the relationship between the tool wear and life time of the end mill were made clear. Finally, this manufacturing method was applied to the gears for a double-helical gear pump. As a result, the validity and effectiveness of the manufacturing method of double-helical gears using a CNC machining center were confirmed.

Effect of honing gear hardness on microgeometry and surface quality improvement of straight bevel gears in PECH process

The present research is directed to investigate pulsed electrochemical honing (PECH) of bevel gears. Honing gears made of 20MnCr5 alloy steel were case hardened (found to have Vicker’s hardness value as 900 HV) using glow discharge plasma nitriding process. The hardened honing gear was used to finish workpiece gear made of same material. Unhardened honing gear having Vicker’s hardness value as 630 HV was also used to finish workpiece gears for comparison. The microgeometry of the workpiece bevel gear was evaluated using deviations in pitch, run-out and topology, while surface quality was evaluated in terms of surface finish, microstructure and microhardness. This research proves that the honing gear hardness is an important aspect for improving the surface quality and microgeometry of the gears. These improvements will enhance service life and operating performance of the PECH-finished gears and will reduce their noise level and chances of their premature failures.

Calibration method for magnetically self-aligned multiball pitch artifact and accuracy upon reassembly

The vibration/noise of gears is influenced by micrometer-order tooth pitch deviation, and therefore advanced quality control is needed in the gear manufacturing process using measuring instruments. The accuracy of the pitch measuring instrument is verified using a master gear or artifact, but its accuracy is not sufficiently high, and its manufacture is difficult. In our previous report, a novel pitch artifact named the magnetically self-aligned multiball pitch artifact, in which elements with simple geometries are aligned spontaneously by a magnetic force, was proposed for the calibration of pitch measuring instruments. The parts comprising the artifact, which consist of balls, a cylinder, and a plane, have simple geometries and can be manufactured with accuracies on the order of several tens of nanometers. Therefore, this artifact can also have high accuracy. In addition, because it undergoes self-alignment by a magnetic force, it has the advantage of easy assembly. An appropriate calibration method for this artifact using a coordinate measuring machine is proposed, and the accuracy of the artifact is evaluated in this report. The repeatability of pitch measurements when the artifact is disassembled and reassembled is investigated, and the results show high repeatability. A measurement experiment using a pitch measuring instrument is performed. These experiments verified that the calibration and measurement of the proposed pitch artifact are possible with high repeatability.

Hierarchical control of ride height system for electronically controlled air suspension based on variable structure and fuzzy control theory

The current research of air suspension mainly focuses on the characteristics and design of the air spring. In fact, electronically controlled air suspension (ECAS) has excellent performance in flexible height adjustment during different driving conditions. However, the nonlinearity of the ride height adjusting system and the uneven distribution of payload affect the control accuracy of ride height and the body attitude. Firstly, the three-point measurement system of three height sensors is used to establish the mathematical model of the ride height adjusting system. The decentralized control of ride height and the centralized control of body attitude are presented to design the ride height control system for ECAS. The exact feedback linearization method is adopted for the nonlinear mathematical model of the ride height system. Secondly, according to the hierarchical control theory, the variable structure control (VSC) technique is used to design a controller that is able to adjust the ride height for the quarter-vehicle anywhere, and each quarter-vehicle height control system is independent. Meanwhile, the three-point height signals obtained by three height sensors are tracked to calculate the body pitch and roll attitude over time, and then by calculating the deviation of pitch and roll and its rates, the height control correction is reassigned based on the fuzzy algorithm. Finally, to verify the effectiveness and performance of the proposed combined control strategy, a validating test of ride height control system with and without road disturbance is carried out. Testing results show that the height adjusting time of both lifting and lowering is over 5 s, and the pitch angle and the roll angle of body attitude are less than 0.15°. This research proposes a hierarchical control method that can guarantee the attitude stability, as well as satisfy the ride height tracking system.

Pitch Patterns in Vocal Expression of 'Happiness' and 'Sadness' in the Reading Aloud of Prose on the Basis of Selected Audiobooks

The primary focus of this paper is to examine the way the emotional categories of “happiness” and “sadness” are expressed vocally in the reading aloud of prose. In particular, the two semantic categories were analysed in terms of the pitch level and the pitch variability on a corpus based on 28 works written by Charles Dickens. passages with the intended emotional colouring were selected and the fragments found in the corresponding audiobooks. They were then analysed acoustically in terms of the mean F0 and the standard deviation of F0. The results for individual emotional passages were compared with a particular reader’s mean pitch and standard deviation of pitch. The differences obtained in this way supported the initial assumptions that the pitch level and its standard deviation would raise in “happy” extracts but lower in “sad” ones. Nevertheless, not all of these tendencies could be statistically validated and additional examples taken from a selection of random novels by other nineteenth century writers were added. The statistical analysis of the larger samples confirmed the assumed tendencies but also indicated that the two semantic domains may utilise the acoustic parameters under discussion to varying degrees. While “happiness” tends to be signalled primarily by raising F0, “sadness” is communicated mostly by lowering the variability of F0. Changes in the variability of F0 seem to be of less importance in the former case, and shifts in the F0 level less significant in the latter.

In Tune or Out of Tune

We studied music majors’ perception of intonation in accompanied solo performances of trumpet, violin, and voice. We were interested in whether listeners would judge pitch deviations of equal magnitude in the three solo performances as equivalent in intonation. Participants were 150 graduate and undergraduate music majors drawn from two large music schools and included 50 students representing each of the following areas of applied music study: voice, wind instruments, and string instruments. Listeners heard solo trumpet, violin, and soprano performances of Ave Maria (Bach/Gounod) accompanied by piano. Pitch performances of the soloists were altered in four sections of the excerpt and deviated in either the sharp or flat direction within a section by 0, 10, 20, and 30 cents relative to the accompaniment. Listeners judged pitch deviations in the flat direction as more out of tune for the trumpet than equivalent alterations of violin and voice, especially for magnitudes of 20 and 30 cents. In sharp direction changes, violin and trumpet were heard similarly and as more out of tune than the vocal soloist. Additionally, differences in pitch judgments were found between listener groups representing different areas of applied study.

Magnetically self-aligned multiball pitch artifact using geometrically simple features

The vibration/noise of gears is influenced by micrometer-order tooth pitch deviation, and therefore, advanced quality control is needed in the gear manufacturing process using measuring instrument. The accuracy of the pitch measuring instrument is verified using a master gear or artifact, but its accuracy is not sufficiently high, and its manufacturing is not easy. In our previous report, a novel high-precision pitch artifact composed of simple-shape parts (“multiball pitch artifact”) was proposed for the calibration of pitch measuring instruments. Simple-shape parts such as balls, cylinders, and planes can be manufactured with several-ten-nanometer-order accuracy. Therefore, this artifact can also have high accuracy. In this study, a magnetically self-aligned multiball pitch artifact is proposed in which the simple-shape parts are assembled with high precision using magnetic force without any special assembly technique. The artifact is designed and manufactured. A measurement experiment using a pitch measuring instrument is performed, and it is verified that the proposed pitch artifact is fundamentally valid for calibration.

Analysis and Compensation for Gear Accuracy with Setting Error in Form Grinding

In the process of form grinding, gear setting error was the main factor that influenced the form grinding accuracy; we proposed an effective method to improve form grinding accuracy that corrected the error by controlling the machine operations. Based on establishing the geometry model of form grinding and representing the gear setting errors as homogeneous coordinate, tooth mathematic model was obtained and simplified under the gear setting error. Then, according to the gear standard of ISO1328-1: 1997 and the ANSI/AGMA 2015-1-A01: 2002, the relationship was investigated by changing the gear setting errors with respect to tooth profile deviation, helix deviation, and cumulative pitch deviation, respectively, under the condition of gear eccentricity error, gear inclination error, and gear resultant error. An error compensation method was proposed based on solving sensitivity coefficient matrix of setting error in a five-axis CNC form grinding machine; simulation and experimental results demonstrated that the method can effectively correct the gear setting error, as well as further improving the forming grinding accuracy.