英语 翻译

(Received 18 February 2008; Revised 13 February 2009)
ABSTRACT−There are three sub-processes associated with the assembly of an automobile transmission: heat fitting, shrink
*Corresponding author. e-mail: chulki@pusan.ac.kr
µ : friction coefficient υ : Poisson’s ratio
1. INTRODUCTION
An automotive’s transmission converts the power generated by the engine to torque. When an automobile is in motion, torque and angular velocity change with variations in speed. Gears located on a rotating shaft are used to transfer motion from the shaft to the wheels.ng process, as opposed to a splint-type fitting process, has frequently been used to squeeze the heated gears toward the outer diameter of the shaft (Ko et al., 2006).
KEY WORDS : Warm shrink fitting process, Automotive transmission, Contact pressure, Fitting load, Interference, Finite
Element Method (FEM), Tooth profile
NOMENCLATURE
r1 : inner radius of shaft r2 : outer radius of shaft or inner radius of gear r3 : outer radius of gear k : radial coefficient, /r3 r2 E : Young’s modulus FSF : shrink fitting force p : contact pressure due to shrink fitting ,pi po : inner and outer pressure ,PA PB : contact force occurred on the Section A/B PT : total contact force, PA+PB α : heat transfer coefficient ∆T : difference between heating and room temperature δSF : the calculated amount of fitting interference δI : the amount of interference used in the field δH : displacement by heating
Although the dimensional tolerance of each part used in the warm shrink fitting process is very precise, it is very difficult accurately forecast the quality of the resulting product. For example, imprecision in conditions such as the temperature and time of shrink fitting make it difficult to determine the amount of expansion or profile variation of
3)Research Institute of Mechanical Technology, Busan National University, Busan 609-735, Korea 4)School of Electrical Engineering, University of Ulsan, Ulsan 680-749, Korea
1)Hyundai Motors Company, 700 Yanjeong-dong, Buk-gu, Ulsan 683-791, Korea 2)Graduate School of Precision Mechanical Engineering, Busan National University, Busan 609-735, Korea
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T. J. KIM et al.
the gears and the contact force between the inner diameter of the gear and the outer diameter of the shaft. Recent research has primarily focused on improving transmission efficiency (Moon et ,al. 2005; Rao and Tjandra, 1994; Sen and Aksakal, 2004; Sung and Kim, 2002); there are only a few studies on fabrication processes. Moreover, research on the shrink fitting process has been limited to the design of the die sets (Besterfield et al., 2003; Chen et al., 2004).
International Journal of Automotive Technology, Vol. 10, No. 5, pp. 611−618 (2009) DOI 10.1007/s12239−009−0072−7
Copyright © 2009 KSAE 1229−9138/2009/048−12
In this paper, a model is developed for predicting contact pressure and fitting load. The model is applied to propose an optimization technique for the warm shrink fitting process. Model accuracy is then verified with experimental results and data from thermal-structural coupled field analysis. A 3D FE (finite element) analysis is carried out to predict the expansion of the outer diameter of the gears.
IMPROVED METHOD FOR ANALYZING AUTOMOTIVE TRANSMISSION PARTS (SHAFT/GEAR) MAFNITUTFIANCGTPURROECDEUSSSING THE WARM SHRINK
T. J. KIM1), H. Y. KIM2), B. C. HWANG3), H. J. KANG4) and C. KIM3)*
fitting, and combination fitting. In the heat fitting stage, the gear is heated to a specified temperature and then squeezed towards the outer diameter of the shaft. The stress of the heat-fitted gear depends on the yield strength of the gear. In the shrink fitting process, the gear is typically squeezed towards the shaft at room temperature using a press. An alternate method, known as warm shrink fitting, heats the already warm gear and safely squeezes it toward the shaft. The warm shrink fitting process for automobile transmission parts is becoming more commonplace, but the additional heating can cause the dimensions of the assembled parts (shaft/gear) to change with respect to both the outer diameter and the profile of the gear. As a result, there may be additional noise and vibration between gears. To address these problems, we analyzed the warm shrink fitting process using the contact pressure caused by fitting interference between the outer diameter of the shaft and the inner diameter of the gear, fitting temperature, and the profile tolerance of the gear as design parameters. In this study, a closed form equation for predicting the contact pressure and fitting load is proposed. This equation is used to develop an optimization technique for the warm shrink fitting process. The reliability of the model was verified using experimental results measured in the field, and FEM with thermal-structural coupled field analysis. Actual loads measured in the field showed good agreement with the results obtained by theoretical and finite element analysis, and expansion of the outer diameters of the gears agreed well with the results.