【機(jī)械類畢業(yè)論文中英文對(duì)照文獻(xiàn)翻譯】通過噴丸改善無級(jí)變速器鋼帶的疲勞強(qiáng)度

【機(jī)械類畢業(yè)論文中英文對(duì)照文獻(xiàn)翻譯】通過噴丸改善無級(jí)變速器鋼帶的疲勞強(qiáng)度,機(jī)械類畢業(yè)論文中英文對(duì)照文獻(xiàn)翻譯,機(jī)械類,畢業(yè)論文,中英文,對(duì)照,對(duì)比,比照,文獻(xiàn),翻譯,通過,改善,改良,無級(jí),變速器,疲勞強(qiáng)度 LETTER Improving the fatigue strength of the elements of a steel belt for CVT by cavitation shotless peening Hitoshi Soyama Masanori Shimizu Yuji Hattori Yuji Nagasawa Received: 9 May 2008 / Accepted: 19 May 2008 / Published online: 6 June 2008 C211 Springer Science+Business Media, LLC 2008 The elements of steel belts used for continuously variable transmission (CVT) are subjected to a bending load during operation. The weakest portion of the elements is at the root of the neck which works into metallic rings. In order to reduce the stress concentration, the root of the neck is rounded and the shape of element is optimized. Nevertheless, if the fatigue strength of the elements can be improved, the steel belt can be applied to larger engines. Although conventional shot peening is one way of enhancing the fatigue strength, it is very difficult for shot to reach into deep and narrow regions. Recently, a peening method using the impact produced as cavitation bubbles collapse has been developed 19. This method is called cavitation shotless peening (CSP), as shot are not required 36, 8. CSP can peen the surface even through deep narrow cavities, as the bubbles can reach these parts and collapse where peening is required. In the present article, improvement of the fatigue strength of the elements of a CVT metallic belt by CSP was demonstrated experimentally. Elements were treated with different processing times and evaluated by a fatigue test to find the optimum processing time. In order to evaluate the peening effect by CSP, the residual stress was measured. Note that this is the first report published on the improvement made in the fatigue strength of a part with regions that cannot be hit directly by shot. Cavitation shotless peening was applied to the element using cavitating jet apparatus, the details of which can be found in references 36, 8. The jet was injected into the neck region through grooves in the elements, which were stacked and held together, and scanned perpendicularly over the elements, as shown in Fig. 1. The processing time per unit length, t p , is defined by the number of scans n and the scanning speed v; t p n v 1 The cavitation number,r, a key parameter for cavitating jets, is defined by the injection pressure, p 1 , the tank pressure, p 2 , and the saturated vapor pressure, p v ,as follows; r p 2 C0 p v p 1 C0 p 2 p 2 p 1 2 r can be simplified as indicated in Eq. 2 because p 1 C29 p 2 C29 p v . Absolute pressure values were used to determine the cavitation number. Considering the results from previous work 36, 8, the CSP conditions shown in Table 1 were selected. The shape of the element tested was identical to actual elements used in steel belts for CVT. The element was made of Japanese Industrial Standards JIS SK5 and was heat treated in the same way as actual elements. In order to examine the improvements made in the fatigue strength, the residual stress of the elements at position A in Fig. 2 was measured using X-ray diffraction with a two-dimensional position sensitive proportional counter (2D PSPC) using the 2D method 10. After CSP, part of the element was cut off and put into the X-ray H. Soyama (&) Tohoku University, 6-6-01 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan e-mail: soyamamm.mech.tohoku.ac.jp M. Shimizu C1 Y. Hattori Toyota Motor Corporation, 1200 Mishuku, Susono 410-1193, Japan Y. Nagasawa Toyota Central R&D Labs. Inc, 41-1 Yokomichi, Nagakute 480-1192, Japan 123 J Mater Sci (2008) 43:50285030 DOI 10.1007/s10853-008-2743-6 apparatus to detect diffractive X-rays, as shown in Fig. 2. A Cr tube operated at 35 kV and 40 mA was used. The diameter of the collimator was 0.1 mm. X-rays were counted for 20 min for each frame. The diffractive plane was the (211) plane of aFe, and the diffractive angle, 2h, was about 156 degree. The values used for Youngs modulus and the Poisson ratio were 210 GPa and 0.28, respectively. The residual stress in the longitudinal direc- tion of the element was obtained from 13 frames using the 2D method. In order to evaluate the fatigue strength of the element, a bending fatigue test was carried out on the element, as shown in Fig. 3. As shown in the figure, the element was fixed and a load F was applied perpendicularly. Figure 4 illustrates the relationship between the number of cycles to failure, N, and the normalized amplitude of the bending force, C22 F, used in the fatigue test, for various pro- cessing times per unit length, t p . The amplitude of the bending force was normalized by the fatigue strength of the non-peened specimen, which was obtained by Littles method 11. The fatigue tests were terminated at N = 10 6 , as it was confirmed that specimens which survived 10 6 cycles also survived 10 7 cycles. From the figure, it is clear that CSP can extend the lifetime of specimens compared to non-peened specimens. The normalized fatigue strength, C22 F FS , of specimens treated by CSP is 1.22 at t p = 2.5 s/mm, 1.38 at t p = 5 s/mm, 1.48 at t p = 10 s/mm, 1.32 at t p = 20 s/mm, and 1.28 at t p = 40 s/mm, respectively. At t p = 10 s/mm, the fatigue strength of the element has been improved by 48% compared with that of the non-peened element. Figure 5 shows the normalized fatigue strength C22 F FS as a function of CSP processing time per unit length, t p . C22 F FS increases with t p until t p = 10 s/mm and then decreases Table 1 CSP conditions Injection pressure p 1 MPa 30 Tank pressure p 2 Mpa 0.42 Cavitation number r 0.014 Nozzle diameter d mm 2 Standoff distance s mm 80 Fig. 2 Measurement position of the residual stress using X-ray diffraction Fig. 3 Schematic diagram of the bending fatigue test of the element Fig. 4 Improvement of the fatigue strength of the element by CSP Fig. 1 Setup of the elements treated by CSP J Mater Sci (2008) 43:50285030 5029 123 slightly. This shows that, as with shot peening, there is an optimum processing time, and that too long processing times cause the fatigue strength to decrease. For the con- ditions applied here, the optimum CSP processing time per unit length was 10 s/mm. Figure 6 shows the variation in the residual stress of the element at position A in Fig. 2 with processing time per unit length, t p . In order to evaluate the reproducibility, the residual stress of two elements was measured for each value of t p using the 2D X-ray diffraction method. Standard deviations for each measurement are shown in Fig. 6. Without CSP, the residual stress was -140 50 MPa and after CSP this was greater than -600 MPa. Thus, CSP can introduce compressive residual stress into the surface even where there are deep and narrow cavities. The impact induced by collapsing cavitation bubbles can introduce compressive residual stress into surfaces that cannot be hit directly by shot (see Fig. 1). The residual stress on the surface increased to between -800 MPa and -1,000 MPa for short processing times, t p = 2.5 s/mm, then decreased slightly saturating at about -800 MPa, as shown in Fig. 6. According to a previous report 5, the compressive residual stress of the sub-surface in materials increases after the residual stress on the surface has saturated. Thus the compressive residual stress of the sub-surface would increase for t p C 2.5 s/mm. This is one of the reasons why the optimum processing time for the present conditions was t p = 10 s/mm, even though the compressive residual stress had reached its maximum at t p = 2.5 s/mm. In order to increase the fatigue strength of the elements of a steel belt for CVT, the elements were treated by CSP. The fatigue strength of the element was evaluated and the residual stress was measured by X-ray diffraction using a 2D method with a 2D PSPC. It was revealed that the fatigue strength of the element could be improved by 48% by CSP. It was also shown that CSP can introduce com- pressive residual stress even into the surface of deep and narrow cavities. This work was partly supported by Japan Society for the Promotion of Science under Grant-in-Aid for Scientific Research (A) 20246030. References 1. Soyama H, Park JD, Saka M (2000) Trans ASME J Manuf Sci Eng 122:83. doi:10.1115/1.538911 2. Soyama H, Kusaka T, Saka M (2001) J Mater Sci Lett 20:1263. doi:10.1023/A:1010947528358 3. Soyama H, Saito K, Saka M (2002) Trans ASME J Eng Mater Technol 124:135. doi:10.1115/1.1447926 4. Odhiambo D, Soyama H (2003) Inter J Fatigue 25:1217. doi: 10.1016/S0142-1123(03)00121-X 5. Soyama H, Sasaki K, Odhiambo D, Saka M (2003) JSME Int J 46A:398. doi:10.1299/jsmea.46.398 6. Soyama H, Macodiyo DO, Mall S (2004) Tribol Lett 17:501. doi: 10.1023/B:TRIL.0000044497.45014.f2 7. Soyama H (2004) Trans ASME J Eng Mater Technol 126:123. doi:10.1115/1.1631434 8. Soyama H, Macodiyo DO (2005) Tribol Lett 18:181. doi: 10.1007/s11249-004-1774-7 9. Soyama H (2007) J Mater Sci 42:6638. doi:10.1007/s10853- 007-1535-8 10. He BB (2003) Powder Diffr 18:71. doi:10.1154/1.1577355 11. Little RE (1972) ASTM STP 511:29 Fig. 5 Optimum CSP processing time per unit length Fig. 6 Introduction of compressive residual stress into the element by CSP 5030 J Mater Sci (2008) 43:50285030 123 附 錄1：英文文獻(xiàn)翻譯及原文通過噴丸改善無級(jí)變速器鋼帶的疲勞強(qiáng)度無級(jí)變速器（CVT）采用的鋼帶在操作過程中要受到彎曲載荷。元件的最薄弱的部分是在作為金屬環(huán)的“頸部”的根部。為了減少應(yīng)力集中，頸部的根部做成圓形，并對(duì)鋼帶的形狀進(jìn)行了優(yōu)化。不過，如果該元件可以提高疲勞強(qiáng)度，鋼帶可應(yīng)用于大引擎。雖然傳統(tǒng)的噴丸是一種提高疲勞強(qiáng)度的方法，但卻很難到達(dá)深而窄的區(qū)域。最近，一種用沖擊產(chǎn)生空化泡爆裂的沖擊法已經(jīng)開發(fā)出來。這種方法稱為“氣穴噴丸”，因?yàn)閲娚洳皇潜匦璧?。由于泡沫可以通過深而窄的通道而到達(dá)凹面，并在需要的地方爆裂，所以CSP可以到達(dá)這些區(qū)域，并對(duì)表面進(jìn)行加工。在本文中，CSP對(duì)無級(jí)變速器鋼帶疲勞強(qiáng)度的提高已被實(shí)驗(yàn)證明。元件分別進(jìn)行了不同時(shí)間的處理，并進(jìn)行了疲勞測(cè)試評(píng)估，以找出最佳的處理時(shí)間。為了評(píng)估CSP噴丸的效果，對(duì)殘余應(yīng)力進(jìn)行了測(cè)量。請(qǐng)注意，這是第一篇發(fā)表的關(guān)于不直接噴射某一部分而使其疲勞強(qiáng)度提高的報(bào)告。CSP使用空化射流裝置應(yīng)用于元件，詳情可見參考文獻(xiàn)。氣體通過堆疊的溝槽注入到元件的頸部，垂直地通過元件，如圖1。每單位長(zhǎng)度的處理時(shí)間tp，由流動(dòng)數(shù)n和流動(dòng)速度v定義：空化射流的關(guān)鍵參數(shù)空化數(shù)r，由注射壓力p1定義，罐內(nèi)壓力p2和飽和蒸氣壓力pv，如下：可用式（2）簡(jiǎn)化表示，因?yàn)閜1p2pv。絕對(duì)壓力值被用來確定空化數(shù)。考慮到以往的工作成果，表1中所示的CSP處理?xiàng)l件是進(jìn)行了篩選的。測(cè)試的元件形狀與無級(jí)變速器實(shí)際使用的鋼帶元件是一樣的。該元件是根據(jù)日本工業(yè)標(biāo)準(zhǔn)JIS SK5制造的，與實(shí)際元件的加熱處理相同。為了檢測(cè)疲勞強(qiáng)度的提高，在圖2的A位置，通過一個(gè)二維位置X -射線衍射靈敏正比計(jì)數(shù)器，用二維的方法對(duì)元件的殘余應(yīng)力進(jìn)行測(cè)量。CSP后，該元素的一部分被切斷，進(jìn)入X -射線衍射儀檢測(cè)X射線，如圖2所示。鉻管在35千伏電壓和40 毫安電流的條件下使用。準(zhǔn)直器直徑為0.1毫米。 X射線計(jì)數(shù)每幀為20分鐘。衍射平面是一個(gè)-Fe平面（211），衍射角2，約156度。楊氏模量和泊松比使用的值分別為210 GPa和0.28。元件的縱向殘余應(yīng)力用二維的方法從13個(gè)單位獲得。 為了評(píng)估元件的疲勞強(qiáng)度，對(duì)元件進(jìn)行了一個(gè)彎曲疲勞測(cè)試，如圖3所示。正如圖所示，該元件是固定的，負(fù)載F為垂直方向。圖4說明了在疲勞測(cè)試中用于多種單位長(zhǎng)度處理時(shí)間tp的循環(huán)失敗次數(shù)N和規(guī)范化的彎曲力振幅之間的關(guān)系。受彎力振幅是由非噴丸樣品的疲勞強(qiáng)度規(guī)范，這是用里特的方法得到的。疲勞試驗(yàn)被終止在N = 106，因?yàn)樗C實(shí)了能承受106次循環(huán)的樣品，也能承受107次。從圖中可明顯看出，相對(duì)于非噴丸樣品，CSP可延長(zhǎng)樣品的壽命。經(jīng)CSP處理的樣品的歸一疲勞強(qiáng)度，當(dāng)tp = 2.5 s/mm時(shí)，為1.22，當(dāng)tp = 5 s/mm時(shí)，為1.38，當(dāng)tp = 10 s/mm時(shí)，為1.48，當(dāng)tp = 20 s/mm時(shí)，為1.32，當(dāng)tp = 40 s/mm時(shí)，為1.28。當(dāng)tp = 10 s/mm時(shí)，元件的疲勞強(qiáng)度相對(duì)于非噴丸元件提高了48%。圖5所示為每單位長(zhǎng)度的CSP處理時(shí)間tp的函數(shù)歸疲勞強(qiáng)度。隨著tp增加而升高，直到tp = 10 s/mm則有所降低。這表明，噴丸存在一個(gè)最佳的處理時(shí)間，如果處理時(shí)間過長(zhǎng)會(huì)造成疲勞強(qiáng)度降低。對(duì)于在這里適用的條件，最佳的CSP每單位長(zhǎng)度的處理時(shí)間為10 s/mm。圖6顯示的是圖2中的A位置元件的殘余應(yīng)力在單位長(zhǎng)度處理時(shí)間tp下的變化情況。為了評(píng)估的重復(fù)性，分別對(duì)兩種元件的殘余應(yīng)力在單位長(zhǎng)度的處理時(shí)間下用二維X射線衍射法進(jìn)行了測(cè)試。 每次測(cè)量的標(biāo)準(zhǔn)偏差如圖6所示。若不用CSP處理，殘余應(yīng)力為-140 50 MPa，而用CSP處理后，殘余應(yīng)力強(qiáng)于-600 MPa。因此，CSP可以對(duì)表面有殘余壓應(yīng)力，即使是深而窄的腔。由空化旗袍爆裂產(chǎn)生的影響可以給表面帶來殘余壓應(yīng)力，是直接噴射所不能做到的（見圖1）。當(dāng)tp = 2.5 s/mm時(shí)，短時(shí)間處理的表面的殘余應(yīng)力提高到-800 MPa and -1,000 MPa之間，然后略有下降到大約-800 MPa，如圖6所示。根據(jù)先前的一份報(bào)告，材料表面的殘余應(yīng)力飽和后，其次表面的殘余壓應(yīng)力會(huì)增加。因此次表面的殘余壓應(yīng)力在tp 2.5 s/mm時(shí)將增加。這就是目前條件下的最佳處理時(shí)間為tp = 10 s/mm的原因之一，即使當(dāng)tp = 2.5 s/mm時(shí)殘余壓應(yīng)力達(dá)到了最大值。為了使無級(jí)變速器鋼帶元件的疲勞強(qiáng)度增加，對(duì)元件進(jìn)行了CSP處理。元件的疲勞強(qiáng)度進(jìn)行了評(píng)估，且通過一個(gè)二維位置X -射線衍射靈敏正比計(jì)數(shù)器，用二維的方法對(duì)元件的殘余應(yīng)力進(jìn)行了測(cè)量。它表明經(jīng)過CSP處理后元件的疲勞強(qiáng)度可提高48%。也證明了CSP可以對(duì)元件表面有殘余壓應(yīng)力，即使是深而窄的腔。附 錄2：英文文獻(xiàn)原文