泵前蓋(泵殼體)加工工藝及其夾具設(shè)計(jì)【鏜上頂面孔(液壓)】【鉆3-φ11孔】【說明書+CAD】

泵前蓋(泵殼體)加工工藝及其夾具設(shè)計(jì)【鏜上頂面孔(液壓)】【鉆3-φ11孔】【說明書+CAD】,鏜上頂面孔(液壓),鉆3-φ11孔,說明書+CAD,泵前蓋(泵殼體)加工工藝及其夾具設(shè)計(jì)【鏜上頂面孔(液壓)】【鉆3-φ11孔】【說明書+CAD】,泵前蓋,殼體,加工,工藝,及其,夾具,設(shè)計(jì),鏜上頂,面孔 Journal of Mechanical Science and Technology 22 (2008) 20092015 10.1007/s12206-008-0407-8 Journal of Mechanical Science and Technology Wear behavior of diamond wheel for grinding optical connector ferrule - FEA and wear test - Chang-Min Suh1,*, Kyo-Seouk Bae1 and Min-Soo Suh2 1School of Mechanical Engineering, Kyungpook National University 1370, Sankyuk-dong, Puk-ku, Daegu, 702-701, Korea 2School of Energy Science, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan (Manuscript Received June 26, 2007; Revised February 11, 2008; Accepted April 10, 2008) - Abstract The grinding characteristics and the wear behavior of diamond wheel for grinding the optical connector ferrule were investigated by finite element analysis (FEA) and wear test. FEA of contact between diamond wheel and ferrule shows that the subsurface damage area of ferrule is 13m from the interface of abrasive particle and matrix. Fallout of abra-sive particle is affected by the stress state at the interface. A 2-D finite element model was established to calculate the distribution of stress at the interface. As the result of FEA, fallout condition of abrasive was concerned with the ratio of the critical protrusion; the ratio of particle size is about 0.6. FE model was established to investigate the effects of the diamond concentration of wheel. The FEA result shows that the lower concentration of it has larger wear volume due to the small stress propagation. To investigate grinding performance, the pin-on-disc wear test was carried out for three types of concentrations 75%, 100% and 125%. Through the wear test, it was confirmed that the 75% wheel concentra-tion has the highest amount of wear volume. This result shows good agreement with that of FEA. And 100% concen-tration by considering the grinding ratio of the wheel shows the best optimized result for the grinding performance. Keywords: Ferrule; FEA (Finite Element Analysis); Diamond wheel; Wear; Pin-on-disc; Grinding - 1. Introduction Grinding with bound abrasives has been exten-sively used in forming and finishing components of many materials 1-5.The demand of parts associated with the advanced optical technology is increasing due to the growth and the expansion of the optical industry. Especially, super-precision optical parts associated with IT, NT and BT requires the high anti-deviation to accomplish the ultra precision machining. The wear characteristics of ceramic materials and cutting tools are important factor to control the preci-sion of the products, and it is widely studied by many researchers: e.g. mechanisms of material removal in grinding ceramics 6, 7, grinding of silicon nitride 8-10, energy concerns with grinding 11-14, and by relating the grinding forces and energy to various parameters associated with the nondeformed chip geometry 15, 16. The understanding of the behavior of both the ma-trix and the diamond abrasives becomes important, due to the wide use of diamond tool 17-20. The severe wear and/or fracture of the diamond wheel are a restriction to mass production; grinding process includes a sacrifice not only the workpiece but also the diamond wheel. The objective of this study is to investigate the wear characteristics of the ceramic ferrule grinding by the diamond wheel. The FE method was used to analyze the stress dis-tribution and the abrasive at the contact area of the ferrule. The wear test was performed to verify the FEA results and to find the optimal condition of grinding from the comparison of each results. This paper was recommended for publication in revised form by Associate Editor Maenghyo Cho *Corresponding author. Tel.: +82 53 950 5573, Fax.: +82 53 950 6550 E-mail address: cmsuhknu.ac.kr KSME & Springer 2008 2010 C.-M. Suh et al. / Journal of Mechanical Science and Technology 22 (2008) 20092015 2. Theoretical background 2.1 Cutting point spacing The successive cutting point spacing and the con-tact arc length are necessary for creating the FE model by considering the concentration. First of all, the contact arc length, lc, is formulated in kinematics of surface grinding, as shown in Eq. (1). 111cvlVDd=+ (1) where, v: workpiece velocity rpm V: wheel velocity rpm, : cutting depth m, d: workpiece diameter mm, D: wheel diameter mm. Theoretical successive cutting point spacing, ath is calculated by Eq. (2). 23gthgdaV= (2) where, dg is an equivalent diameter mm when the abrasive is assumed as sphere, and Vg is the ratio of abrasive particle. 2.2 Grinding force for single abrasive The Merchants theory was used to evaluate the specific grinding energy of a single abrasive to create the FE model as a micro element of the grinding wheel. Fallout of an abrasive is mainly affected by tangential grinding force. The value of tangential grinding force was 2.3110-4 N. This value was set up on the load condition of the FE model. 2.3 Grinding force acting on the abrasive Shaw model 21 was used in this study. Applying the Shaw model to the FE model, the diamond shape particle was converted into the sphere which has a diameter of 20 m and the frictional force was ne-glected. Tangential grinding force was considered as a direct relationship with the fallout of abrasives. 2.4 Specific wear rate and grinding ratio Wear of the wheel is related to the amount of grind-ing. Inverse value of the specific wear rate is grinding ratio, G as shown in Eq. (3). GT S= (3) where, T is the wear volume of material, and S is the wear volume of wheel. The parameter G was evalu-ated to use as a standard of the economic efficiency of the diamond wheel. 3. Characteristics of materials 3.1 Characteristics of the zirconia ferrule TZP (Tetragonal Zirconia Polycrystal) was used in this study as the test material. It has been using widely in broad industry because of the excellence in hardness, strength/weight ratio, thermal stability, and corrosion resistance. 3.2 Characteristics of the diamond wheel Table 1 shows the material properties of a diamond and resin, which is the specification of the diamond wheel. In case of machining the ferrule, the diamond wheel which is made by a phenolic resin is used; it has relatively high elasticity but low grinding resis-tance. Phenolic resin can bring a high revolution and a high grinding amount due to a proper removing flash and scale. Generally the phenolic resin is used but fiber reinforced phenolic resin is also used in spe-cial demand. Elastic modulus of the diamond wheel applied in FE simulation was 46 GPa which was de-termined by an elastic modulus of grade N. Table 1. Material properties and specification of the diamond wheel. Properties Diamond Resin Elastic Modulus (GPa) 1171 7 Poissons ratio 0.1 0.3 Concentration 100% Mesh # (abrasive size) #400(40m) Grade N (46 GPa) Outer diameter 60 mm Inner diameter 20 mm Thickness 5 mm C.-M. Suh et al. / Journal of Mechanical Science and Technology 22 (2008) 20092015 2011 4. Finite element analysis 4.1 Contact analysis between wheel and ferrule 4.1.1 Finite element model The interacting surface, where the grinding area is minutely divided by 4-node rectangular plane of strain elements, is to generate the most accurate gra-dient for the stress which is large at this area. Motion of the model was described as the wheel and ferrule has a relative rotations and the ferrule was fed into the wheel. In this analysis, the cutting depth was set as one tenth of the real cutting depth for ana-lyzing the contact instantly. Time duration was set as 1 ms. During at 0.4 ms, the ferrule was moved in front of the diamond wheel, and during at another 0.3 ms, the grinding was processed. The rest of the time, the grinding process has ended. In this analysis, the stick-slip friction model was used at the interface of the wheel and ferrule. 4.1.2 Result of finite element analysis Fig. 1 shows the stress variations at the interface between the wheel and ferrule for the depth from the contact point. Ferrule stress exceeded its own flexural strength, 1 GPa, after the contact duration at 0.1 ms. After this moment, the grinding process has been progressed rapidly by the fracture propagation of the ferrule. Fig. 2 shows the distributions of the von Mises stresses between the wheel and ferrule for the depth from the contact point. The greatest amplitude of stress was generated on the contact point and de-creased as the increase of its depth from the contact point. The stress reaches to the flexural strength under 100 m depths from the contact point. The stress at the area, under about 63 m depth from the surface, has exceeded its flexural strength of 1 GPa. The esti-mated subsurface damage was about 13 m except for the cutting depth of 50 m . 4.2 Interface analysis between abrasive and resin 4.2.1 Finite element model Normal force and frictional force were generated by the relative motion of the abrasive and ferrule. These forces will generate the stress at the contact interface between abrasive and resin. This state of stress is determined by the load and wear amount of the abrasive 5. Semi-infinite matrix model was created, which has 600 times larger size than real Fig. 1. Magnified distribution of von Mises stress at the con-tact interface. -10001002003004005006007008000246 ferrule stress wheel stress von-Mises stress(GPa)Depth from contact surface to conter(m) ) Fig. 2. Variation of von Mises stress of ferrule and wheel versus the depth from contact surface. diamond abrasive. The stick-slip condition was se-lected as the boundary condition of the contact inter-face. 4.2.2 Finite element model for the wear mechanisms Four types of assumptions for models were used as wear mechanisms in this analysis. No wear; a sym-metric wear, the symmetrical wear before the dia-mond particle detached; an asymmetric wear which occurs only in one side around the resin of the dia-mond particle and the other side remains; and a parti-cle wear which its amount of abrasive is relatively higher than that of resin. 4.2.3 Result of finite element analysis Fig. 3 shows the stress distribution of all models. Fig. 3 (b) and (d) shows a state of moment just be-fore the breakaway of the abrasive. The stress con-centration occurred at the corner of the particle. The stress concentration has the greatest value, especially at the root of the particle. The stress concentration 2012 C.-M. Suh et al. / Journal of Mechanical Science and Technology 22 (2008) 20092015 (a) No wear (b) Symmetric wear (c) Particle wear (d) Asymmetric wear Fig. 3. Four kinds of stress distribution for the interface of abrasive and resin. 0510152025303501x1032x1033x1034x1035x1036x103Particle wear von-Mises stress (N/m2)Node number 0 1 2 3 4 5 6 7 8 9 Fig. 4. Variation of von Mises stress versus node number as a function of particle wear. was increased at the root of the particle as the wear progressed in both case of the wear, symmetric and the asymmetric. The stress at the interface of the resin and particle was higher than the stress at the particle tip, which directly applied to the grinding force. The ratio of the uncovered and covered part which led the breakaway of abrasive is about 0.6 and it corresponds with other paper 5. Fig. 4 shows the stress distribution of the interface for nine cases of the particle wear. The characteristics of each specimen after and before the tests are listed in Table 2. The stress amplitude is three or four times larger than that of symmetric and asymmetric wear. The smaller stress of the interface between the abra-sive and resin was, therefore, estimated at the root of the abrasive. In this case, it can be estimated that the wheel have to perform the dressing process. Table 2. Grinding ratio and wear volume of the ferrule and diamond wheel. nomenclatureLength of fer-rule before test Length of wheel after testWear volume of ferrule Wear volume of wheel Grinding ratio, G1-1 10.477.81 52.18 0.62 80.03 1-2 10.476.27 82.40 0.83 98.84 1-3 10.487.95 49.63 0.50 99.49 2-1 10.487.33 61.80 0.77 80.24 2-2 10.466.38 80.04 0.73 109.54 2-3 10.457.57 56.50 0.63 89.38 3-1 10.466.93 69.25 0.76 91.15 3-2 10.466.13 84.95 0.68 125.73 3-3 10.467.78 52.58 0.58 94.21 Table 3. Three models of diamond concentration of wheel. Concentration Vg ;ratio of abrasive particle ath 75 % 0.1875 96.0 100 % 0.5200 72.0 125 % 0.3125 57.6 4.3 Analysis for the wheel concentration 4.3.1 Finite element model The diamond concentration was used as a parame-ter for the evaluation. The grinding wheel consists of abrasive, resin and void. The role of void is to collect the chip; mainly affects on the discharge of the chip. Table 2 shows the successive cutting point spacing of the three different concentrations which was derived by the Eq. (2), and the ratio of the abrasive for the concentration of it. In each case, diamond concentra-tion has the number of abrasive particles 75 % has 4; 100 % has 5; and 125 % has 6. Contact arc length, calculated by Eq. (1), was 374 m and is applied to the model. There are two constraint conditions one is x direction at two side edges and the other is y direc-tion at the bottom of the model. 4.3.2 Result of finite element analysis The equivalent strain distribution of 100 % dia-mond concentration is shown in Fig. 5. The distri-butions of the strain are similar to the distributions of stress except for abrasives. The tensile side of the matrix, which applied the grinding force and the side edge, has a greater strain. This is caused by the stress concentration at the side edge. The larger the C.-M. Suh et al. / Journal of Mechanical Science and Technology 22 (2008) 20092015 2013 Fig. 5. An example of strain distribution according to the 100 % concentration of the diamond wheel. concentration of the diamond is, the larger the strain occurs. In case of the 75 % concentration, the border strain of the first particle was larger than the second one where the minimum value of the strain located closely. The phenomenon of 100 % concentration, similar to 125 %, was opposite to that of 75 % concentration. In case of the low concentration, the space among the particles was far from each other so that the influence among the particles hardly existed. Consequently, the strain of the first particle was relatively large and widely distributed due to the grinding force acting on the first diamond particle was larger than any other ones. In case of the 100 % concentration, the interac-tion between the first and second particle is not negli-gible because of the space among the particles was closer than that of 75 %. Because of the influence among the abrasive parti-cles, the strain has increased as the increase of con-centration; the stress has decreased. The stress at the interface of the matrix and abrasive has relaxed ac-cording to the increase of the wheel concentration. It can be assumed that the factor of the abrasive fallout becomes weaken by the increase of the concentration. 5. Wear test 5.1 Result of wear test The wear test of pin-on disc type was performed for diamond wheels which had different concentra-tions. The atmosphere was in-air temperature, no lubricated. The coefficient of friction was in the range of 0.44 to 0.46, in all test condition. In other words, it can verify that the unstable wear behavior has not occurred during the test. Fig. 6 shows bar charts of the wear volumes of the ferrule and the diamond wheel. The wear volume of ferrule became large about 10 times rather than that of wheel. The wear volume of the 75 % concentration was the smallest one. The higher the diamond con-centration is, the smaller wear of wheel occurs. In 1-11-21-32-12-22-33-13-23-30102030405060708090 Wear volume ( (mm3) )Specimen Number Wear volume of ferrule Wear volume of wheel(x10) Fig. 6. Bar chart of the wear volumes of ferrule and wheel. 75%100%125%80859095100105110115120125130 Grinding ratio GConcentration 1 set 2 set 3 set Fig. 7. Variation of grinding ratio, G versus concentration ratio. case of the 100 % concentration, the ferrule has the largest wear volume. It looks like that the self-sharpening occurred but the glazing or loading has hardly occurred. Fig. 7 shows the grinding ratio of each test set. In case of 100 %, it has the highest grinding ratio. In case of 75 %, on the other hand, it has the lowest grinding ratio. And in the case of 125 %, it was esti-mated to have the highest the grinding ratio due to the smallest wear volume. 5.2 Microscopic observation of wear surface Fig. 8 shows SEM photography of the sectional view that diamond wheel of 75% concentration. A void, that many particles are shed in the resin, can be seen as V mark. A solid line indicates an interface of the surface and the section of the diamond wheel. The particle traces of breakaway can be observed. In case of the 125 % concentration, the traces of the diamond (marked as D) of breakaway have not been observed, and the grinding face has a flat surface. If 2014 C.-M. Suh et al. / Journal of Mechanical Science and Technology 22 (2008) 20092015 Fig. 8. SEM photography of 75 % concentration wheel (500) shows voids(V) and diamond particles(D). the grinding face becomes as the flat surface, the grinding resistance will be increased. And then, the wear occurs in the processing face of ferrule and wheel. Thus the quality of the ground face of ferrule becomes a low level. 6. Conclusions The result of contact analysis shows that the area of subsurface damage becomes 13m when the depth of cutting is 50 m. The result of interface analysis shows that the abra-sive breakaway condition is the ratio of the critical protrusion; the breakaway of abrasive particle is about 0.6. The result of FEA according to concentration ratio, the lower diamond concentration ratio has the higher stress concentration due to the lower interactive among the abrasives particles. Abrasive breakaway is, therefore, faster and the wear of the diamond wheel is propagated rapidly. These results are well corre-sponded with those of the wear test and also con-firmed by the SEM observation. The optimal condition of the diamond concentra-tion ratio is 100 % and the worst condition of it is 75 %. Acknowledgments This research was supported by the Program for Training of Graduate Student in Regional Innovation which was conducted by the Korea Industrial Tech-nology Foundation and the Ministry of Commerce, Industry and Energy of the Korean Government. References 1 Peter Blake, Thomas Bifano, Thomas Dow, Ronald O Scattergood, Precision Machining of Ceramic Materials, American Ceramic Society Bulletin 67 (6) (1988)1038-1041. 2 S. Malkin and J. E. 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Malkin, High speed grinding of silicon nitride with electroplated diamond wheels, part 1: Wear and wheel life, Journal of Manufacturing Science and Engineering, Transactions of the ASME 122 (1) (2000) 32-41. 10 T. W. Hwang, C. J. Evans and S. Malkin, High Speed Grinding of Silicon Nitride With Electro-plated Diamond Wheels, Part 2: Wheel Topography and Grinding Mechanisms, Journal of Manufactur-ing Science and Engineering, Transactions of the ASME 122 (1) (2000) 42