機(jī)械扳手的新設(shè)計(jì)外文文獻(xiàn)翻譯、中英文翻譯
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機(jī)械扳手的新設(shè)計(jì) 全聯(lián)盟的石油機(jī)械研究機(jī)構(gòu)解釋了基于不同設(shè)計(jì)的機(jī)械扳手傳遞扭矩的規(guī)律性,由此明確的一點(diǎn)就是通過(guò)扳手咬合施加力所產(chǎn)生的30—40KNm扭矩足夠用來(lái)傳遞更高的扭矩(>80KNm)。由此及彼,通過(guò)減少與扭矩成正比例管子上扳手顎的強(qiáng)度使得減少扳手的重量并且增加它們的可靠性成為可能。當(dāng)然,在產(chǎn)生夾緊力的初期我們必須保證扳手不能滑動(dòng)。然而,傳統(tǒng)設(shè)計(jì)的機(jī)械扳手不能保證在扳手扭動(dòng)過(guò)程中力變化的規(guī)律性?;诓煌O(shè)計(jì)下扳手強(qiáng)化機(jī)構(gòu)的特征表述在『1』 在腦海中我們應(yīng)該記住的就是扳手和管子的接觸在很大程度上與杠桿的旋轉(zhuǎn)角度α有關(guān)。然后,隨著扳手杠桿外力的增加,這個(gè)角度變得越來(lái)越小,從左到右加緊螺紋的整個(gè)過(guò)程見(jiàn)圖1 強(qiáng)化機(jī)構(gòu)最有效率的結(jié)合可以由聯(lián)動(dòng)機(jī)構(gòu)和鉸鏈機(jī)構(gòu)得到。當(dāng)管子第一次被加緊的時(shí)候,鏈接機(jī)構(gòu)就開(kāi)始工作了(曲線1);它的工作區(qū)域由杠桿切縫的尺寸來(lái)限制,然后就轉(zhuǎn)到由四連桿機(jī)構(gòu)操作(曲線2)來(lái)確定最高強(qiáng)化系數(shù)。當(dāng)杠桿最末端那一面上升到最終夾緊連接時(shí),強(qiáng)化機(jī)構(gòu)便從曲柄設(shè)計(jì)和通過(guò)不同長(zhǎng)度桿來(lái)連接的連接桿機(jī)構(gòu)(曲線4)中得到收益。因此,在經(jīng)過(guò)考慮的這個(gè)例子中,扳手連接在管子上的強(qiáng)度開(kāi)始的強(qiáng)化系數(shù)是i=18—20,增至i=42—45,并且以i=12—13結(jié)束。 通過(guò)鉸鏈設(shè)計(jì)的扳手加緊過(guò)程以強(qiáng)化系數(shù)i>25(曲線2,3)結(jié)束。這也就解釋了為什么這些扳手會(huì)比聯(lián)動(dòng)機(jī)構(gòu)和鉸鏈機(jī)構(gòu)的扳手重20%。 聯(lián)動(dòng)機(jī)構(gòu)和鉸鏈機(jī)構(gòu)的另一個(gè)明顯的優(yōu)勢(shì)應(yīng)當(dāng)被提及:杠桿工作有著大范圍的旋轉(zhuǎn)角度:-15 度 < α < 30 度 。 我們調(diào)查的結(jié)果被用來(lái)作為計(jì)算有著轉(zhuǎn)矩極限的混合鉸鏈機(jī)構(gòu)KMB108—2112的基礎(chǔ)。這些扳手設(shè)計(jì)的特殊之處就在于在管子上扳手夾緊過(guò)程中減少了1/2或者1/3的強(qiáng)化系數(shù)。這就是依靠特殊轉(zhuǎn)矩極限應(yīng)用到最末端表面杠桿制動(dòng)力的結(jié)果。 扳手控制聯(lián)動(dòng)機(jī)構(gòu)和鉸鏈機(jī)構(gòu)。扭矩極限,楔形斷面的一部分,鉸接到扳手的加緊部分。在杠桿最末端表面有一個(gè)相同截面的架子作為扭矩極限的凹槽。 扳手開(kāi)始的時(shí)候是由鉸鏈機(jī)構(gòu)來(lái)操控;當(dāng)動(dòng)作限制在滑動(dòng)槽的時(shí)候,就開(kāi)始由鉸接四連桿機(jī)構(gòu)來(lái)控制,當(dāng)大約達(dá)到所能達(dá)到最大夾緊力的一般時(shí),就由緊緊鑲嵌在扭矩限制槽里面的杠桿架來(lái)操控。 由于有著最末級(jí)扳手杠桿的制動(dòng)影響,它所形成的夾緊部分的動(dòng)力鏈接中兩杠桿大約等于三杠桿的效果,這一點(diǎn)與第五設(shè)計(jì)的強(qiáng)化系數(shù)(看圖1)相符。因此,在扳手KMB108—212中,一個(gè)合理的操作過(guò)程形成了:進(jìn)程開(kāi)始時(shí)大的強(qiáng)化系數(shù)(i<45度),在杠桿上小的驅(qū)動(dòng)力(在扳手和管子之間獲得可靠的連接力)并且在得到大的驅(qū)動(dòng)力時(shí)強(qiáng)化系數(shù)的減少(避免扳手過(guò)載)。應(yīng)變儀測(cè)量表明在那種情況下扳手鏈接的最大壓力被減少1/3到一半。 一個(gè)扳手原型KMB108—212,計(jì)算出額定轉(zhuǎn)矩為80KNm,被用207.5KNm的轉(zhuǎn)矩在the Azerbaidzhan Institute of Petroleum Machinery的測(cè)試臺(tái)上進(jìn)行測(cè)試。扳手的效率沒(méi)有絲毫的削弱。在1985年KMB108—212扳手開(kāi)始連續(xù)生產(chǎn)。然而,這些工具的全容量生產(chǎn)被扳手的不穩(wěn)定質(zhì)量限制了。 附錄D NEW DESIGN OF MACHINE WRENCH FOR DRILLING AND DRIVING PIPES At the All-Union Research Institute of Petroleum Machinery investigations were carried out revealing the regularities of the transmission of torque by machine wrenches based on different schemes. It was thereby established that the clamping forces of the jaws exerted by the machine wrench at torques of 30-40 kNm suffice for transmitting much higher torques (>80 kNm). In connection with that it therefore becomes possible to reduce the weight of the wrenches and increase their reliability by reducing the intensity of the clamping of the spanner jaws on the pipes in proportion to the increase of torque. Of course, at the initial stage of loading a clamping force has to be ensured that makes slippage of the wrench impossible. However, machine wrenches of traditional design do not ensure the necessary regularity of the change of forces in the gripping links of the wrench. The characteristics of the intensifying mechanisms of wrenches based on different schemes are presented in [i]. It should be borne in mind that contact of the wrench with the pipe occurs at large values of the angles of rotation ~ of the lever. Then, as the drawing force on the lever of the wrench increases, the angle ~ becomes smaller, i.e., the process of tightening the thread proceeds from right to left (see Fig. i). The most efficient combination of intensifying mechanisms can be obtained in wrenches with link gear and hinged mechanism. When the pipe is gripped first, the link mechanism acts (curve i); its zone of action is limited by the size of the slit in the lever. Then comes the transition to operation by the hinged four-link mechanism (curve 2) ensuring the highest coefficients of intensification. When the end face of the lever comes up against the final gripping link, intensification proceeds by the scheme of the crank and connecting rod mechanism (curve 4) with a connecting rod of variable length. Thus, in the case under consideration, tightening of the wrench links on the pipe begins at an intensification coefficient i = 18-20, which increases to i = 42-45, and ends with i = 12-13. With wrenches with hinged scheme the process of tightening ends with the coefficient of intensification i > 25 (curves 2, 3). This also explains why these wrenches weigh 20%[2] more than wrenches with link gear and hinged mechanism. Another substantial advantage of the link gear and hinged wrench should be mentioned: the wider range of working angles of rotation of the lever: -15 < e < 30 . For wrenches with the hinged scheme -5 < ~ < 18 ~because of the unreliable gripping with i < 18-20 at the onset of the process and the better operation of such wrenches by the scheme of the crank and connecting rod mechanism (curve3). The results of our investigations were made the basis for working out the multihinge machine wrench KMB 108-2112 for drilling pipes with torque limiter [3]. The special feature of the design of these wrenches consists in the reduction of the coefficient of intensification to one-half or one-third when the process of tightening the wrench on the pipe is concluded; this is the result of a braking force being applied to the end face of the lever by means of a special torque limiter. The wrench operates on the link gear and hinge mechanism scheme. The torque limiter, a part with a groove of wedge-shaped section, is hinged to the drawing link of the gripping part of the wrench. On the end face of the lever there is a rack with the same section as the groove of the torque limiter. The wrench begins to operate by the link gear scheme; when the motion is limited in the slide groove, it operates by the scheme of the hinged four-link mechanism, and when approximately half the maximal drawing force is attained, it operates by a scheme where the rack of the lever fits tightly into the groove of the torque limiter. Thanks to the effective braking of the wrench lever at the last stage, it forms with the drawing link of the gripping part a two-armed lever with the ratio of the arms approximately equal to three, which corresponds to the coefficient of intensification of the fifth scheme (see Fig. i). Thus in the wrench KMB 108-212 a rational combination of t]he operating regimes was effected: with large intensification (i <_ 45) at the beginning of the process with small drawing loads on the lever (to attain reliable cohesion between the wrench and the pipe) and with considerable reduction of the intensification when high drawing loads are attained (to prevent overloading of the wrench). Strain-gauge measurements showed that in that case the maximal stresses in the links of the wrench are reduced by one third to one half. A prototype of the wrench KMB 108-212, calculated for a nominal torque of 80 kN~ was tested on a test bench of the Azerbaidzhan Institute of Petroleum Machinery with a torque of 207.5 kN-m. The efficiency of the wrench was not impaired in any way. In 1985 series production of the wrenches KMB 108-212 started. However, production to full capacity of these tools is prevented by the unstable quality of cast blanks for the wrench.- 1.請(qǐng)仔細(xì)閱讀文檔,確保文檔完整性,對(duì)于不預(yù)覽、不比對(duì)內(nèi)容而直接下載帶來(lái)的問(wèn)題本站不予受理。
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