机械设计外文翻译-珩磨和硬滚齿之间的加工过程分析【中文3580字】【PDF+中文WORD】
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机械设计外文翻译-珩磨和硬滚齿之间的加工过程分析【中文3580字】【PDF+中文WORD】,中文3580字,机械设计,外文,翻译,硬滚齿,之间,加工,过程,分析,中文,3580,PDF,WORD
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Energy Procedia 14 (2012) 2 81876-6102 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the organizing committee of 2nd International Conference on Advances in Energy Engineering (ICAEE).doi:10.1016/j.egypro.2011.12.888Available online at *Corresponding author: Tel +51 16 3373-8604; fax +5116 3373-9402 E-mail address: silveirasc.usp.br ICAEE 2011 2nd International Conference in Energy Engineering Finishing process analysis between honing and hard hobbing in pinion gears applied to a steering system Sandro Pereira dos Santosa, Lincoln Cardoso Brandob, Luis Henrique Gallicchioc, Zilda de Castro Silveiraa,* a Department of Mechanical Engineering, Sao Carlos School of Engineering, University of Sao Paulo. Post code 13560-590, Brazil.bFederal University of Sao Joao del Rei, Post code 36307-352, Brazil cTRW Automotive, Brazil. Abstract Among the techniques used in surface finish machining of gears, the honing process has been highlighted due to high efficiency in the finishing of hardened gears and ease of adjusting the involutes profile and incident angle in the counter-part. The gear honing process is used to eliminate errors that appears after the heat treatment on the tooth surface and. Although the material and cutting speed of the tool are similar to the grinding process, honing the process simulates true cinematic movement of the mesh gear, which provides a better surface roughness compared to the Hobbing process. Consequently, it is hard to correct anomalies in the gear teeth. This process has been used to improve the mechanisms hydraulic steering pinion / rack system. For the experiments, it were compared two processes, namely honing and hard Hobbing in order to assess the adequate strength in the direction of clockwise rotation and counter clockwise, which represents the actual effort exerted by the driver of the vehicle. The honing process was lead using a 400 Fassler HMX machine tool. In order to assess the significant difference between the experiments, it was used ANOVA and Tukey test. The results obtained from the experiments using the honing process were satisfactory as compared the results obtained from hard hobbing process. Thus, it can be concluded that this process provides an excellent surface finish of the sprockets having a direct impact on the returned vehicle steering system. 2011 Published by Elsevier Ltd. Keywords: honing; roughness, steering system, pinion, hard hobbing. 1. Introduction Gears are among the most important parts of machine elements of the modern industry due to their ability to transmit motion and generate power. There are a wide variety of industrial applications, in which gears are essential parts of many technical systems such as vehicles, ships, power generation systems, machine tools and gearboxes. The manufacturing process can be made using different tools 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the organizing committee of 2nd International Conference on Advances in Energy Engineering (ICAEE).Gallicchio and Zilda de Castro Silveira / Energy Procedia 14 (2012) 2 83 and technical approaches. The grinding process is used to generate the final profile providing improvement of size, shape, accuracy and surface quality in the final product. According to Fssler 1 the design gear teeth is complex due the specific shape and roughness accuracy. In this way, improvements in the surface finishing ensure operational high-performance. The current processes more used to generate the involutes gears profiles are Hard Hobbing and Honning. Hard Hobbing is the process more frequent for cutting gear teeth. In this process, the cog is generated using the cutting tool (hob) and part (gear) while constantly rotating the hob in direction of the part. According to Dudley 2, Michalec 3 and Lynwander 4, the “Hobbing” is a versatile and economical process for cutting gear teeth and its only restriction would be to manufacture internal gear teeth and when there is sufficient axial space to withdarw tool. The honing process has already been widely used due to the high efficiency of the finishing of the hardened gears and its ease of fitting the profile and the angle of incidence on the mating piece. It is used for debugging after heat treatment on the surface of gear teeth. The kinematics of this process and tool geometry is similar to the initial cut gear profile. Moreover, the material and cutting speed of the tool are similar to the grinding process see Silva 5. According to Silva 6, the Honing process simulates the true cinematic movement of the gear mesh, which generates a surface roughness better than the grinding process. This process is the use a dressing internal toothed wheel composed of a base standard epoxy and a dresser with diamond-coating with the exact geometry of the product. In the manufacturing process using wheel honing the profile is predefined. The honing tool is a multipoint cutting tool where the geometry of the grinding wheel is transferred exactly to generate the profile of gear involutes (final product). A considerable reduction in noise coupling can be achieved with the Honing gear process. Generally, the process to generate the gear tooth profile is followed for a Honing process. This paper proposes a comparative study in the generation of the pinion profile used on hydraulic steering system between honing process and hard hobbing considering errors helix of the sprocket wheel. 1.1. Methodology The experiments were run in an American company specialized in manufacturing auto steering systems. Pinions for steering systems were used as specimens, as shown in Figure 1. The pinions are made of SAE4320-H in the core hardness ranging from 295/460 HV2 and a layer of cement on the surface of 600 HV2. The specifications about dimensions and finishing involutes tooth profile are based on technical standardizes: ISO 1328-1 (1995) 8, ISO 1328-2 (1997) 9, ISO TR 10064-1 (1992) 10, DIN 3962 11 and DIN 3962 12. Fig. 1. Pinion used to the experiments. The equipment used in the experiment was a machining center for the specific Honing brand Fssler HMX-400 process model with nine degrees of freedom. For the Hard Hobbing process a brand of machining center model Pfauter Gleason - P60 with 8 degrees of freedom was used. Both devices are based on commands used in machining center model SINUMERIK 840 D. Honing process was 4 Gallicchio and Zilda de Castro Silveira / Energy Procedia 14 (2012) 2 8 performed with an internal toothed wheel dresser the epoxy (Figure 2a) to finishing of the sprockets. In the process of Hard Hobbing, a tool was used with pigments cubic boron nitrate (CBN) type Snail (Figure 2b). (a) (b) Fig. 2. (a) Details of the toothed wheel Fssler 1; (b) Detail of the CBN tool like snail. The grinding wheel used in the experiment presents a composition of aluminum oxide (Al2O3), synthetic compound (sintered aluminum oxide) and silicon carbide binder pressing on the basis of an epoxy resin. The modulus of elasticity of the alloy wheel is 21 N/m2 and it has a density of 2.45 g/cm3 Hermes 7. Figure 3a shows details of the wheel mounting system and clamping head with tweezers. The pinion is mounted on the plate and has a second point of support located inside the milling head. The z-axis moves in the axial direction of the machine, exactly the size of the length of the pinion to be machined. Figure 3b shows details of the system of fixing the pinion in the milling head to the Hard Hobbing process. The pinion is fixed by means of account-points and the X axis moves in the axial direction of the product removing of material in the evolving profile and helix angle. (a) (b) Fig. 3. (a) Details of the milling head, HMX-400 Fssler 1, (b)Details of the milling head, Pfauter - P60. Therefore, the aim of this study is to conduct a comparative study between Hard Hobbing and Honing process using samples of the 30 specimens machined in each process. The acceptance criteria used was based on measurement of profile and helix angle according to the design specifications of the product and DIN 3962 (1978). Figure 5 shows the diagram of the measurement and representation of the deviations of the transverse profile of the tooth. The deviation measurements from the transverse profile of the teeth of the pinion were taken in a special measuring gear manufacturer Strjirny elkovice Czech called SPECT Gear 3 PC model, as shown in Figure 6. To evaluate the significant difference in the attributes between the two processes the Gallicchio and Zilda de Castro Silveira / Energy Procedia 14 (2012) 2 85 analysis of variance and Tukey test were used at 5% significance level. The Analysis of Variance (ANOVA) and Test Averages were performed in Minitab software. Fig. 4. (a) Equipments used to measure teeth gear; (b) CrossSection, Silva 5 3. Analysis and Discussion of Results The ANOVA 13, considering 5% significance level for the left and right sides of the curve (Table 1 and Table 2) was found FCAL is greater than Ftab. In this way, the hypothesis Ho is rejected, indicating that there is the mean difference between treatments, so, for each of the variables investigated there are not significant difference between Hard Hobbing and Honing processes (p-value 0.05). Table 1. ANOVA for the left side of the helix.Table 2 . ANOVA for the right side of the helix. FV = from variation; GL = degrees of freedom; SQ = Sum of Squares; QM = Square Mean; Fc = Fcalculated; CV (%) = coefficient of variation. FV = from variation; GL = degrees of freedom; SQ = sum of squares; QM = Square Mean; Fc = Fcalculated; CV (%) = coefficient of variation. In addition, the Tukey test at 5% significance level showed that the Honing process had lower values of dimensional errors compared to the Hard Hobbing process (Table 3). 6 Gallicchio and Zilda de Castro Silveira / Energy Procedia 14 (2012) 2 8 Table 3. Mean values of errors helix in the sprockets wheel. Due to the fact that a grinding wheel was used, it was observed that the Honing process minimizes the effects of risks for deviations of the tool profile, shape and inclination of the tooth, where the ripples caused by the milling tools higher rank. Furthermore using this process, the total error of the cross-section is minimized due to a constant correction of the profile of the tool. Through the process of dressing, which cannot be done in the milling process, the Hard Hobbing process has little flexibility to adjust, since the profile of the teeth of the tool is rigid snail, allowing the copy of your profile at the gear tooth, as they suffer wear the changed profile is also replicated to the gear. The graphs in Figures 6 and 7 presents the forces needed to turn the steering to the right or left for the two milling processes and honing, respectively. Data acquisition to evaluate and monitor comfort while driving was developed using the program LabVIEW to the processing of data directly when testing components. In figure 6, force to the left and right can be observed when the steering system is driven by the driver. Tests were conducted under the same conditions that the driver needs to control the direction of the vehicle. The objective is to evaluate the graph concerning the comfort that can be divided into three ranges: force within the region of maximum comfort, strength outside the region of maximum comfort and minimum force. It can be seen that three peaks take place during the tests in Figure 6. By evaluating both figures 6 and 7, it can be observed that the peaks generated when the steering system is turned, regardless of the side for the milling process, are much higher and significant than the honing process. These peaks represent the effects of gear set pinion / rack being turned into little bumps and causing minor vibrations in the driver s hands when steering. Figure 7 shows that these peaks are much lower resulting in a turning smoother and safety. Fig. 7. Power to rotate the steering system with the hard hobbing process. Gallicchio and Zilda de Castro Silveira / Energy Procedia 14 (2012) 2 87 Figure 8. Power to rotate the steering system with the Honing process. All results obtained for the minimum and maximum efforts during testing when the steering system was turned towards the left or right are presented in Table 4. The graphs represent the generated data acquisition kgf. In Table 4, the values experimentally obtained were converted to the International System. It can be seen that the values are very close with a reduction in strength for the honing process around 10% on average, than may at first, meaning a very small value for the technology used. However, the minimum force in these tests showed a reduction of 33% which is an important variable due to the fact that represents the minimum force to keep the steering straight observing an increase in driving comfort significantly. Moreover, it is possible to consider that the design of the two processes is very different because the Honing process used unconventional or undefined geometries and gears milling is a specific called Hobbing process that use specific geometries. Table 4. Force values during the tests with the steering systems. 4. Conclusion The experimental procedure developed from the errors of involutes gear teeth allowed a better understanding about the operational conditions of the gear transmissions. Firstly, the honing process provides a finishing surface and roughness with high quality that allows an engagement between surface gears without noise. Besides, the honing process is more flexible when compared to the hard hobbing due to the dimensional corrections of the profile of pinion. It is possible observe that the hard hobbing process have not major adjustments to the dimensional conditions for stiffness in the dimensional characteristics of snail tool. The quality of the engagement process before the Honing and hard hobbing process is practically the same with exception of deviation of inclination of the tooth, (FH), which indicate variations of 5.27 and 5.13 micrometer for the process hard hobbing and 4.93 and 5.07 for the honing process, right and left flanks, respectively. The quality of tooth gear indicated to Ff (removal of tooth shape) presented a reduction of 7.77 and 9.20 micrometer in process hard hobbing and 6.47 to 8 Gallicchio and Zilda de Castro Silveira / Energy Procedia 14 (2012) 2 8 2.47 compared to honing process due to the path improvement Honing tool during the machining process maintaining the ideal profile for cutting. The quality of the tooth gear F (total deviation of tooth profile) presented small differences between the right flank against the left, maintaining a reduction of 8.53 and 10.53 to the hard hobbing process and 4.27 and 5.70 obtained in the honing process. The next step will be vary some operational parameters using a formal experiments (Design of Experiments) to investigate the influence of its parameters on the response as machining time and surface quality. Acknowledgements The authors like to thank the TRW Automotive Ltd. located in Lavras - Minas Gerais, Brazil for providing the operational infrastructure and to the CAPES for providing the funding for the paper. References 1 Fssler Cost
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