Beginning Of Engagement Research Articles

Influence of S0 Type of Addendum Modification on Sliding Performance of Spur Gears

The effect of S0 type of addendum modification on sliding velocity of the involute spur gear has been studied. For the analysis four critical points such as Beginning of Engagement, Low Point of Single Tooth Contact, High Point of Single Tooth Contact and Disengagement point corresponding to pinion are considered. Length of approach and length of recess for modified gears are evaluated. Effects of addendum modification on contact fatigue life and wear prediction are discussed. Product of contact stress and sliding velocity ( σh * Vs) at critical points for varied addendum modification factor X are evaluated, and its effect on sliding velocity has been analysed. Effect of change in value (σh * Vs) at critical points of contact for modified gear pair on Hertzian fatigue is discussed.

風損低減を目的とした歯車の自己ポンプ作用の実験的評価（箱内の減圧量，損失および発熱について）

Windage loss may become more than 10% of all losses when large sized gearing runs fast. In order to reduce the windage loss, it needs to vacuum a gear box because it is proportional to the density of ambient air. The study proposes a helical gearing unit in which interior air is discharged due to mesh process as like as a gear pump, and investigates the performance experimentally in terms of depressure level, power loss and temperature rise due to heat generation. The pressure in the gear box got to - 0.08MPa under appropriate condition, but the temperature rose up to about 200°C. Losses were measured and found to consist of four types in self-vacuuming: mechanical loss, windage loss, pressure difference loss, and turning flow loss. Among them pressure difference loss was the most marked part which is due to the gears rotating against pressure difference between high and low pressure atmosphere, or the beginning of engagement and end of it, respectively, in the gear box. Furthermore existence of turning flow loss was confirmed due to circulation flow in the wide exhaust opening volume, and it was eliminated by changing the exhaust port to such as an axial narrow hole. The temperature rise was proven to the effect of adiabatic compression and corresponding energy dissipation. It was verified by the calculation based on the typical thermal dynamics at tooth space which consists of isovolumetric, isobaric, and adiabatic changes. By calculating the required kinematic work of this cycle, the result matched with the pressure difference loss. Furthermore a small external vacuum pump can collaborate to assist reducing this pressure difference loss.

Constant Acceleration Control for AMT's Application in Belt Conveyor's Soft Starting

In order to start belt conveyor softly, automated mechanical transmission (AMT) is used as a new soft-starting device. Constant belt acceleration control is proposed as a method for AMT’s application in belt conveyor’s soft starting. Belt velocity is adopted as the single parameter for shift schedule. Based on the idea of half engagement point, fast-slow-fast law is taken for clutch engagement. Simulation model is established in AMESim environment. On the basis of horizontal belt conveyor driven by one induction motor with 110 KW power, simulation research on start-up process in first gear and shift process from first gear to eighth gear are carried out respectively. Simulation results show that the constant belt acceleration with 0.2 m/s 2 could achieve the purpose of AMT’s application in belt conveyor’s soft starting. The phenomenon of short-time belt acceleration mutations appears during shift process. The maximum value of belt acceleration is less than 1 m/s 2 while the clutch is just at the beginning of engagement. Under the influence of belt acceleration mutations, main characteristic parameters of the system are within their allowable limits, such as belt maximum tension and driving pulley torque. After the completion of upshift process, the belt maximum tension and other parameters curves tend to be stable.

Effects of Rim and Web Thicknesses on Root Stresses of Thin-Rimmed Helical Gear

This paper presents a study on root stresses of thin-rimmed helical gears with web arrangement of various rim and web thickness. Thin-rimmed helical gears used in this study were meshed with solid helical gear. Root stresses were measured from the beginning of engagement to the end of engagement by using the strain gauge method. The changes of root stresses from the beginning of engagement to the end of engagement were examined and the meshing position where the maximum root stress occurred (worst loading position) was determined. Effects of rim and web thickness on the root stress, the maximum root stress and the position of maximum root stress were clarified.

Detection of Wheel and Workpiece Contact/Release in Reciprocating Surface Grinding

This paper evaluates the performance and limitations of a simple algorithm to detect contact and release events in reciprocating surface grinding by processing the output of a piezoelectric force transducer. It efficiently detects these events independent of workpiece material, wheel type, or grinding conditions (except for dry grinding with low material removal rates). The purpose of this algorithm is to prevent force overshoot at the beginning of engagement in the study of subsurface plastic deformation.

クリープフィード研削における上向きおよび下向き研削機構の相違

This paper aims to reveal the difference in grinding mechanism between up- and down-cut creep feed grindings. According to the experiments, both the normal and tangential components of mean grinding force have always become larger in up-cut than in down-cut under the usual creep feed grinding conditions, and the difference has become 1. 7 times at maximum. It was found from the force measurements on a single grain that its normal to tangential ratio remained constant at about 2.5 throughout a grain-workpiece engagement in down-cut, but it became up to about 7 at the beginning of engagement in up-cut, which implies much occurrences of rubbing and/or plowing, hence leading to a larger grinding force. Then it is introduced that this mean grinding force at down-cut can be estimated quantitatively from the conventional grinding force data.