帶傳動的類型和特點(diǎn)

PAGEPAGE99第八章帶傳動第一節(jié)帶傳動的類型和特點(diǎn)帶傳動由主動帶輪1、從動帶輪2和撓性帶3組成，借助帶與帶輪之間的摩擦或嚙合，將主動輪1的運(yùn)動傳給從動輪2，如圖8-1所示。圖8-1圖8-1帶傳動示意圖根據(jù)工作原理不同，帶傳動可分為摩擦帶傳動和嚙合帶傳動兩類。1.摩擦帶傳動摩擦帶傳動是依靠帶與帶輪之間的摩擦力傳遞運(yùn)動的。按帶的橫截面形狀不同可分為四種類型，如圖8-2所示。(1)平帶傳動。平帶的橫截面為扁平矩形（圖a），內(nèi)表面與輪緣接觸為工作面。常用a)b)c)d)圖8-2a)b)c)d)圖8-2帶傳動的類型(2)V帶傳動。V帶的橫截面為梯形，兩側(cè)面為工作面（圖b），工作時V帶與帶輪槽兩側(cè)面接觸，在同樣壓力FQ的作用下，V帶傳動的摩擦力約為平帶傳動的三倍，故能傳遞較大的載荷。(3)多楔帶傳動。多楔帶是若干V帶的組合(圖c),可避免多根V帶長度不等,傳力不均的缺點(diǎn)。(4)圓形帶傳動。橫截面為圓形(圖d),常用皮革或棉繩制成,只用于小功率傳動。2.嚙合帶傳動嚙合帶傳動依靠帶輪上的齒與帶上的齒或孔嚙合傳遞運(yùn)動。嚙合帶傳動有兩種類型，如圖8-3所示。(1)同步帶傳動。利用帶的齒與帶輪上的齒相嚙合傳遞運(yùn)動和動力，帶與帶輪間為嚙合傳動沒有相對滑動，可保持主、從動輪線速度同步（圖a）。(2)齒孔帶傳動。帶上的孔與輪上的齒相嚙合，同樣可避免帶與帶輪之間的相對滑動，使主、從動輪保持同步運(yùn)動（圖b）。二、帶傳動的特點(diǎn)摩擦帶傳動具有以下特點(diǎn)：(1)結(jié)構(gòu)簡單，適宜用于兩軸中心距較大的場合。(2)膠帶富有彈性，能緩沖吸振，傳動平穩(wěn)無噪聲。(3)過載時可產(chǎn)生打滑、能防止薄弱零件的損壞，起安全保護(hù)作用。但不能保持準(zhǔn)確的傳動比。(4)傳動帶需張緊在帶輪上，對軸和軸承的壓力較大。(5)外廓尺寸大,傳動效率低(一般0.94~0.96)。a)同步齒形帶傳動b)齒孔帶傳動圖8-3嚙合帶傳動根據(jù)上述特點(diǎn)，帶傳動多用于①中、小功率傳動（通常不大于100KW）；②原動機(jī)輸出軸的第一級傳動（工作速度一般為5~25a)同步齒形帶傳動b)齒孔帶傳動圖8-3嚙合帶傳動第二節(jié)V帶和帶輪帶的構(gòu)造和標(biāo)準(zhǔn)a)簾布結(jié)構(gòu)b)線繩結(jié)構(gòu)圖8-4V帶剖面結(jié)構(gòu)標(biāo)準(zhǔn)V帶都制成無接頭的環(huán)形，其橫截面由強(qiáng)力層1、伸張層2、壓縮層3和包布層4構(gòu)成，如圖8-4所示。伸張層和壓縮層均由膠料組成，包布層由膠帆布組成，強(qiáng)力層是承受載荷的主體，分為簾布結(jié)構(gòu)（由膠簾布組成）和線繩結(jié)構(gòu)（由膠線繩組成）兩種。簾布結(jié)構(gòu)抗拉強(qiáng)度高，一般用途的V帶多采用這種結(jié)構(gòu)。線繩結(jié)構(gòu)比較柔軟，彎曲疲勞強(qiáng)度較好，但拉伸強(qiáng)度低，常用于載荷不大，直徑較小的帶輪和轉(zhuǎn)速較高的場合。Va)簾布結(jié)構(gòu)b)線繩結(jié)構(gòu)圖8-4V帶剖面結(jié)構(gòu)V帶和帶輪有兩種尺寸制，即有效寬度制和基準(zhǔn)寬度制?；鶞?zhǔn)寬度制是以V帶的節(jié)寬為特征參數(shù)的傳動體系。普通V帶和SP型窄V帶為基準(zhǔn)寬度制傳動用帶。按GB/T11544-97規(guī)定，普通V帶分為Y、Z、A、B、C、D、E七種，截面高度與節(jié)寬的比值為0.7；窄V帶分為SPZ、SPA、SPB、SPC四種，截面高度與節(jié)寬的比值為0.9。帶的截面尺寸如表8-1所示，基準(zhǔn)長度系列如表8-2所示。窄V帶的強(qiáng)力層采用高強(qiáng)度繩芯，能承受較大的預(yù)緊力，且可撓曲次數(shù)增加，當(dāng)帶高與普通V帶相同時其帶寬較普通V帶小約1/3,而承載能力可提高1.5~2.5倍。表8-5V帶輪的基準(zhǔn)直徑系列（摘自GB/T13575.1-92）(mm)基準(zhǔn)直徑dd(c11)帶型基準(zhǔn)直徑dd(c11)帶型YZSPZASPABSPBCSPCDEYZSPZASPABSPBCSPCDE外徑da(h11)外徑da(h11)2022.4252831.535.5404550566371758085909510010611211812513214015023.225.628.231.234.738.743.248.253.259.266.274.283.293.2103.2115.2128.2*54*606775798494104116129136144154*80.5*85.5*90.595.5100.5105.5111.5117.5123.5130.5137.5145.5155.5*132*139147157160170180200212224236250265280300315335355375400425450475500530560600630670164184204228254284319359404504634165.5185.5205.5229.5255.5285.5320.5360.5405.5455.5505.5565.5635.5167177187207231257287322362407457507567607637*209.6*221.6233.6245.6259.6289.6309.6324.6344.6364.6409.6459.6509.6569.6609.6639.6371.2391.2416.2441.2466.2491.2516.2572.2616.2646.2519.2549.2579.2619.2649.2689.2注:*只用于普通V帶第三節(jié)V帶傳動工作能力分析一、帶傳動的受力分析帶以一定的預(yù)緊力套在帶輪上。靜止時帶輪兩邊的拉力相等，均為預(yù)緊力F0，如圖8-7a)所示。負(fù)載轉(zhuǎn)動時，由于帶與帶輪接觸面摩擦力的作用，帶繞上主動輪的一邊被拉a)b)圖8-7帶傳動的受力分析緊，稱為緊邊，緊邊的拉力由F0增加到F1；另一邊被放松，稱為松邊，拉力由F0降至F2。如圖8-7b)所示。緊邊與松邊拉力的差值a)b)圖8-7帶傳動的受力分析F=F1－F2(8-1)若帶傳遞功率為P（KW）、帶速為v（m/s）則：N(8-2)如果近似的認(rèn)為工作前后膠帶總長不變，則帶的緊邊拉力增量應(yīng)等于松邊拉力的減少量，即F1－F0＝F0－F2，即：(8-3)由式（8-1）、（8-3）得：(8-4)二、帶傳動的應(yīng)力分析帶在工作過程中主要承受拉應(yīng)力，離心應(yīng)力和彎曲應(yīng)力三種應(yīng)力。三種應(yīng)力迭加后，最大應(yīng)力發(fā)生在緊邊繞入小帶輪處，其值為：≤（8-5）式中：σ1=F1/A為緊邊拉應(yīng)力(MPa),A為帶的橫截面積(mm2)；σb1=Eh/dd為帶繞過小帶輪時發(fā)生彎曲而產(chǎn)生的彎曲應(yīng)力,E為帶的彈性模量(MPa),h為帶的高度(mm),dd為帶輪的基準(zhǔn)直徑(mm)；σC=qv/A為帶繞帶輪作圓周運(yùn)動產(chǎn)生的離心應(yīng)力，q為每米長帶的質(zhì)量（kg/m），見表（8-1）。在帶的高度h一定的情況下，dd越小帶的彎曲應(yīng)力就越大，為防止過大的彎曲應(yīng)力對各種型號的V帶都規(guī)定了最小帶輪直徑dmin如表8-6所示。表8-6V帶輪的最小基準(zhǔn)直徑型號YZSPZASPABSPBCSPCDEddmin(mm)2050637590125140200224355500三、帶的彈性滑動和打滑1.彈性滑動由于帶傳動存在緊邊和松邊，在緊邊時帶被彈性拉長，到松邊時又產(chǎn)生收縮，引起帶在輪上發(fā)生微小局部滑動，這種現(xiàn)象稱為彈性滑動。彈性滑動造成帶的線速度略低于帶輪的圓周速度，導(dǎo)致從動輪的圓周速度v2低于主動輪的圓周速度v1,其速度降低率用相對滑動率表示。相對滑動率＝0.01~0.02,故在一般計(jì)算中可不考慮，此時傳動比計(jì)算公式可簡化為：（8-6）2.打滑與極限有效拉力當(dāng)外載較小時，彈性滑動只發(fā)生在帶即將由主、從動輪離開的一段弧上。傳遞外載增大時，有效拉力隨之加大，彈性滑動區(qū)域也隨之?dāng)U大，當(dāng)有效拉力達(dá)到或超過某一極限值時，帶與小帶輪在整個接觸弧上的摩擦力達(dá)到極限，若外載繼續(xù)增加，帶將沿整個接觸弧滑動，這種現(xiàn)象稱為打滑。此時主動輪還在轉(zhuǎn)動，但從動輪轉(zhuǎn)速急劇下降，帶迅速磨損、發(fā)熱而損壞，使傳動失效。所以必須避免打滑，在設(shè)計(jì)時應(yīng)限制帶的最大拉力。當(dāng)帶有打滑趨勢時，帶與帶輪間的摩擦力達(dá)到極限值，即有效拉力達(dá)到最大值，這時可由歐拉公式推導(dǎo)得極限有效拉力為：（8-7）式中：e為自然對數(shù)的底，；f為摩擦系數(shù)（V帶用當(dāng)量摩擦系數(shù)代替，）；為包角，即帶與帶輪接觸弧對應(yīng)的中心角（rad），因大帶輪包角總是大于小帶輪包角，故這里應(yīng)取為小帶輪包角。第四節(jié)普通V帶傳動設(shè)計(jì)計(jì)算一、設(shè)計(jì)準(zhǔn)則和單根V帶的額定功率1.設(shè)計(jì)準(zhǔn)則根據(jù)帶傳動工作能力分析可知，帶傳動的主要失效形式有：①帶在帶輪上打滑，不能傳遞動力；②帶發(fā)生疲勞破壞（經(jīng)歷一定應(yīng)力循環(huán)次數(shù)后發(fā)生拉斷、撕裂、脫層）。因此帶傳動的設(shè)計(jì)準(zhǔn)則為：①帶在傳遞規(guī)定功率時不發(fā)生打滑,即滿足式（8-7）。②具有一定的疲勞強(qiáng)度和壽命,即滿足式（8-5）。2.單根V帶所能傳遞的額定功率。經(jīng)推導(dǎo)可得單根V帶所能傳遞的額定功率為：（8-8）式中：v為帶速m/s。在特定帶長、使用壽命、傳動比(i=1、)以及在載荷平穩(wěn)條件下，通過疲勞試驗(yàn)測得帶的許用應(yīng)力后，代入式（8-8）便可求出特定條件下的P0值，見表8-7。表8-7包角=180o、特定帶長、工作平穩(wěn)情況下，單根V帶的額定功率P0(KW)型號小帶輪直徑dd1(mm)小帶輪轉(zhuǎn)速n1(r/min)20040073080098012001460160020002400280032003600Z5663718090－－－－－0.060.080.090.140.140.110.130.170.200.220.120.150.200.220.240.140.180.230.260.280.170.220.270.300.330.190.250.310.360.370.200.270.330.390.400.250.320.390.440.480.300.370.460.500.540.330.410.500.560.600.350.450.540.610.640.370.470.580.640.68A75901001121251401600.160.220.260.310.370.430.510.270.390.470.560.670.780.940.420.630.770.931.111.311.560.450.680.831.001.191.411.690.520.790.971.181.401.662.000.600.931.141.391.661.962.360.681.071.321.621.932.292.740.731.151.421.742.072.452.940.841.341.662.042.442.873.420.921.501.872.302.743.223.801.001.642.052.512.983.484.061.041.752.192.683.163.654.191.081.832.282.783.263.724.17B1251401601802002240.480.590.740.881.021.190.841.051.321.591.852.171.341.692.162.613.063.591.441.822.322.813.303.861.672.132.723.303.864.501.932.473.173.854.505.262.202.833.644.415.155.992.333.003.864.685.466.332.643.424.405.306.137.022.853.704.755.676.477.252.963.854.895.766.436.952.943.834.805.525.956.052.803.634.464.924.984.47續(xù)表8-7630.200.350.560.600.700.810.931.001.171.321.451.561.66710.250.440.720.780.921.081.251.351.591.812.002.182.33SPZ750.280.490.790.871.021.211.411.521.792.042.272.482.65800.310.550.880.991.151.381.601.732.052.342.612.853.06900.370.671.121.211.441.701.982.142.552.933.263.573.841000.430.791.331.441.702.022.362.553.053.493.904.264.58900.430.751.211.301.521.762.022.162.492.773.003.163.261000.530.941.541.651.932.272.612.803.273.673.994.254.42SPA1120.641.161.912.072.442.863.313.574.184.715.155.495.721250.771.402.332.522.983.54.064.385.155.806.346.767.031400.921.682.813.033.584.234.915.296.227.017.648.118.391601.112.043.423.704.385.176.016.477.608.539.249.729.941401.081.923.133.353.924.555.215.546.316.867.157.176.891601.372.474.064.375.135.986.897.338.389.139.529.539.10SPB1801.653.014.995.376.317.388.509.0510.3411.2111.6211.4310.772001.943.545.886.357.478.7410.0710.7012.1813.1113.4113.0111.832242.284.186.977.528.8310.3311.8612.5914.2115.1015.1414.22—2502.644.868.118.7510.2711.9913.7214.5116.1916.8916.44——2242.905.198.388.9910.3911.8913.2613.8114.5814.01———2503.506.3110.2711.0212.7614.6116.2616.9217.7016.69———SPC2804.187.5912.4013.3115.4017.6019.4920.2020.7518.86———3154.979.0714.8215.9018.3720.8822.9223.5823.4719.98———3555.8710.7217.5018.7621.5524.3426.3226.8025.3719.22———4006.8612.5620.4121.8425.1527.3329.4029.5325.81————型號小帶輪直徑d1(mm)小帶輪轉(zhuǎn)速n1(r/min)10020030040050060073098012001460160018002000C200224250280315400——————1.391.702.032.422.863.911.922.372.853.404.045.542.412.993.624.325.147.062.873.584.335.196.178.523.304.125.006.007.149.823.804.785.826.999.3411.524.665.897.188.6510.2313.675.296.718.219.8111.5315.045.867.479.0610.7412.4815.516.077.759.3811.0612.7215.246.288.009.6311.2212.6714.086.348.059.6211.0412.1411.95D3554004505005603.013.664.375.085.915.316.527.909.2110.767.359.1311.0212.8815.079.2411.4513.8516.2018.9510.9013.5516.4019.1722.3812.3915.4218.6721.7825.3214.0417.5821.1224.5228.2816.3020.2524.1627.6031.0017.2521.2024.8427.6129.6716.7020.0322.4223.2822.0815.6318.3119.5918.8815.1312.9714.2813.349.59——————E5005606307108006.217.328.7510.3112.0510.8613.0915.6518.5221.7014.9618.1021.6925.6930.0518.5522.4926.9531.8337.0521.6526.2531.3636.8542.5324.2129.3034.8340.5846.2626.6232.0237.6443.0747.7928.5233.0037.1439.5639.0825.5328.4929.1725.9116.4616.2514.52——————————————————二、帶傳動設(shè)計(jì)步驟和參數(shù)選擇設(shè)計(jì)V帶傳動的原始數(shù)據(jù)為帶傳遞的功率P,轉(zhuǎn)速n1、n2（或傳動比）以及外廓尺寸的要求等。設(shè)計(jì)內(nèi)容有：確定帶的型號、長度、根數(shù)、傳動中心距、帶輪直徑以及帶輪結(jié)構(gòu)尺寸等。設(shè)計(jì)步驟一般為：1.確定設(shè)計(jì)功率Pc（8-9）式中：P為帶傳遞的額定功率（KW）；KA為工況系數(shù)，見表（8-8）。表8-8工況系數(shù)KA載荷性質(zhì)工作機(jī)原動機(jī)空、輕載啟動重載啟動每天工作小時數(shù)h<1010～16>16<1010～16>16載荷變動微小液體攪拌機(jī)、通風(fēng)機(jī)和鼓風(fēng)機(jī)（≤7.5KW）、離心式水泵和壓縮機(jī)、輕型輸送機(jī)1.01.11.21.11.21.3載荷變動小帶式輸送機(jī)（不均勻負(fù)荷）、通風(fēng)機(jī)（>7.5KW）旋轉(zhuǎn)式水泵和壓縮機(jī)（非離心式）、發(fā)電機(jī)、金屬切削機(jī)床、旋轉(zhuǎn)篩、鋸木機(jī)和木工機(jī)械1.11.21.31.21.31.4載荷變動較大制磚機(jī)、斗式提升機(jī)、往復(fù)式水泵和壓縮機(jī)、起重機(jī)、磨粉機(jī)、沖剪機(jī)床、旋轉(zhuǎn)篩、紡織機(jī)械、重載輸送機(jī)1.21.31.41.41.51.6載荷變動很大破碎機(jī)（旋轉(zhuǎn)式、顎式等）、磨碎機(jī)（球磨、棒磨磨、管磨）1.31.41.51.51.61.8注：①空輕載啟動—電動機(jī)（交流啟動、三角啟動、直流并勵）、四缸以上的內(nèi)燃機(jī)、裝有離心式離合器、液力聯(lián)軸器的動力機(jī)；②重載啟動—電動機(jī)（聯(lián)機(jī)交流啟動、直流復(fù)勵或串勵）、四缸以下的內(nèi)燃機(jī)；③反復(fù)啟動、正反轉(zhuǎn)頻繁、工作條件惡劣等場合，KA應(yīng)乘以1.2。2.選擇V帶的型號根據(jù)設(shè)計(jì)功率Pc和主動輪轉(zhuǎn)速n1由圖8-8、9選擇帶的型號。3.確定帶輪的基準(zhǔn)直徑dd1和dd2小帶輪直徑dd1應(yīng)大于或等于表8-6所列的最小直徑dmin。dd1過小則帶的彎曲應(yīng)力設(shè)計(jì)功率Pc設(shè)計(jì)功率Pc/（KW）圖8-8普通V帶選型圖圖8-8普通V帶選型圖設(shè)計(jì)功率Pc/設(shè)計(jì)功率Pc/（KW）圖8-9窄V帶選型圖dd1、dd2均應(yīng)符合帶輪直徑系列尺寸，見表8-5。4.驗(yàn)算帶速v(8-10)帶速太高離心力增大，使帶與帶輪間的摩擦力減小，容易打滑；帶速太低，傳遞功率一定時所需的有效拉力過大，也會打滑。一般應(yīng)使普通V帶5m/s＜v＜25m/s窄V帶5m/s＜v＜35m/s否則重選dd1。5.確定中心距a和帶的基準(zhǔn)長度Ld在無特殊要求時，可按下式初選中心距a0：≤ao≤mm(8-11)由帶傳動的幾何關(guān)系，可得帶的基準(zhǔn)長度計(jì)算公式：mm(8-12)按查表8-2得相近的V帶的基準(zhǔn)長度Ld，再按下式近似計(jì)算實(shí)際中心距：a≈a0+（8-13）當(dāng)采用改變中心距方法進(jìn)行安裝調(diào)整和補(bǔ)償初拉力時，其中心距的變化范圍為（8-14）6.驗(yàn)算小帶輪包角≥（8-15）1與傳動比有關(guān)，愈大（dd2－dd1）差值愈大，則1愈小。所以V帶傳動的傳動比一般小于7,推薦值為2~5。速比不變時，可用增大中心距a的方法增大1。7.確定V帶根數(shù)zz≥（8-16）式中：Pc為設(shè)計(jì)功率，按式（8-9）計(jì)算；P0為特定條件下單根V帶所能傳遞的功率（KW），查表（8-7）；ΔP0為i＞1時的額定功率增量（KW），查表（8-9）；K為包角系數(shù)，考慮不是特定長度時，對傳動能力的影響，查表（8-10）。8.確定單根V帶初拉力F0（8-17）9.計(jì)算帶對軸的壓力FQFQ（8-18）表8-9考慮i≠1時，單根V帶的額定功率增量△P0(KW)型號傳動比i小帶輪轉(zhuǎn)速n1(r/min)20040073080098012001460160020002400280032003600Z1.00～1.01—1.02～1.04—0.000.021.05～1.08—1.09～1.12—0.011.13～1.18—0.031.19～1.24—1.25～1.34—0.021.35～1.51—1.52～1.99—.0.040.05≥2.0—帶速v(m/S)51015A1.00～1.010.001.02～1.040.020.020.020.030.030.040.040.051.05～1.080.010.020.020.030.030.040.040.060.070.080.090.101.09～1.120.020.030.030.040.050.060.060.080.100.110.130.151.13～1.180.020.040.040.050.070.080.090.110.130.150.170.191.19～1.240.030.050.050.060.080.090.110.130.160.190.220.241.25～1.340.020.030.060.060.070.100.110.130.160.190.230.260.291.35～1.510.020.040.070.080.080.110.130.150.190.230.260.300.341.52～1.990.020.040.080.090.100.130.150.170.220.260.300.340.39≥2.00.030.050.090.100.110.150.170.190.240.290.340.390.44帶速v(m/S)51015202530續(xù)表8-91.00～1.010.000.000.000.000.000.000.000.000.000.000.000.000.001.02～1.040.010.010.020.030.030.040.050.060.070.080.100.110.131.05～1.080.010.030.050.060.070.080.100.110.140.170.200.230.251.09～1.120.020.040.070.080.100.130.150.170.210.250.290.340.381.13～1.180.030.060.100.110.130.170.200.230.280.340.390.450.51B1.19～1.240.040.070.120.140.170.210.250.280.350.420.490.560.631.25～1.340.040.080.150.170.200.250.310.340.420.510.590.680.761.35～1.510.050.100.170.200.230.300.360.390.490.590.690.790.891.52～1.990.060.110.200.230.260.340.400.450.560.680.790.901.01≥2.00.060.130.220.250.300.380.460.510.630.760.891.011.14帶速v(m/S)5101520253035401.00～1.010.000.000.000.000.000.000.000.000.000.000.000.000.001.02～1.050.000.000.010.010.010.010.020.020.020.030.030.040.041.06～1.110.010.010.020.030.030.040.050.050.070.080.090.110.121.12～1.180.010.020.040.050.060.070.080.090.120.140.160.180.201.19～1.260.020.030.060.060.080.090.110.130.160.190.220.250.28SPZ1.27～1.380.020.040.070.080.090.110.140.150.190.230.270.310.341.39～1.570.020.040.080.090.110.130.160.180.220.270.310.360.401.58～1.940.030.050.090.100.120.150.180.200.250.300.350.400.461.95～3.380.030.060.100.110.130.160.200.220.270.330.380.440.49≥3.390.030.060.100.120.140.170.210.230.290.350.410.470.52帶速v(m/S)51015201.00～1.010.000.000.000.000.000.000.000.000.000.000.000.000.001.02～1.050.000.010.020.020.030.030.040.040.050.060.070.080.101.06～1.110.020.030.050.060.070.090.100.120.140.170.200.230.261.12～1.180.030.050.090.100.120.150.180.200.250.300.350.400.451.19～1.260.030.070.120.140.160.210.240.270.340.410.480.540.62SPA1.27～1.380.040.080.150.170.200.250.300.330.410.500.580.660.751.39～1.570.050.100.170.200.230.290.350.390.490.590.680.780.881.58～1.940.050.110.190.220.260.330.400.440.550.660.770.880.991.95～3.380.060.120.210.240.280.360.430.480.600.720.840.951.07≥3.390.060.130.220.250.300.380.460.510.630.760.891.011.14帶速v(m/S)51015202530351.00～1.010.000.000.000.000.000.000.000.000.000.000.000.000.001.02～1.050.010.020.040.040.050.070.080.090.110.130.150.170.201.06～1.110.030.060.110.120.150.180.220.240.300.360.420.470.531.12～1.180.050.100.190.210.250.310.380.410.520.620.720.830.931.19～1.260.070.140.260.280.340.420.510.560.700.840.981.131.27SPB1.27～1.380.090.170.310.340.420.510.620.680.851.021.191.361.531.39～1.570.100.200.360.400.490.600.730.801.001.201.401.601.801.58～1.940.110.220.410.450.550.680.820.901.131.351.581.812.031.95～3.380.120.250.450.490.600.740.890.981.231.471.721.962.21≥3.390.130.260.470.520.640.780.951.041.301.561.822.082.34帶速v(m/S)5101520253035401.00～1.010.000.000.000.000.000.000.000.000.000.00———1.02～1.050.030.050.100.110.130.160.190.210.260.32———1.06～1.110.070.140.260.290.350.430.530.580.720.86———1.12～1.180.130.250.460.500.620.750.921.001.251.51———1.19～1.260.170.340.620.680.841.021.241.361.712.05———SPC1.27～1.380.210.410.750.831.011.241.511.652.072.48———1.39～1.570.240.490.890.971.191.461.771.942.432.92———1.58～1.940.270.551.001.101.341.642.002.192.743.28———1.95～3.380.300.591.081.191.461.782.172.382.973.57———≥3.390.320.631.151.261.551.892.302.523.153.79———帶速v(m/S)10152025303540續(xù)表8-9型號傳動比i小帶輪轉(zhuǎn)速n1（r/min）100200300400500600730980120014601600180020001.00～1.01—0.000.000.000.000.000.000.000.000.000.000.000.001.02～1.04—0.020.030.040.050.060.070.090.120.140.160.180.201.05～1.08—0.040.060.080.100.120.140.190.240.280.310.350.391.09～1.12—0.060.090.120.150.180.210.270.350.420.470.530.591.13～1.18—0.080.120.160.200.240.270.370.470.580.630.710.78C1.19～1.24—0.100.150.200.240.290.340.470.590.710.780.880.981.25～1.34—0.120.180.230.290.350.410.560.700.850.941.061.171.35～1.51—0.140.210.270.340.410.480.650.820.991.101.231.371.52～1.99—0.160.240.310.390.470.550.740.941.141.251.411.57≥2.0—0.180.260.350.440.530.620.831.061.271.411.591.76帶速v(m/S)5101520253035401.00～1.010.000.000.000.000.000.000.000.000.000.000.000.00—1.02～1.040.030.070.100.140.170.210.240.330.420.510.560.63—1.05～1.080.070.140.210.280.350.420.490.660.841.011.111.24—1.09～1.120.100.210.310.420.520.620.730.991.251.511.671.88—1.13～1.180.140.280.420.560.700.830.971.321.672.022.232.51—D1.19～1.240.170.350.520.700.871.041.221.602.092.522.783.13—1.25～1.340.210.420.620.831.041.251.461.922.503.023.333.74—1.35～1.510.240.490.730.971.221.461.702.312.923.523.894.98—1.52～1.990.280.560.831.111.391.671.952.643.344.034.455.01—≥2.00.310.630.941.251.561.882.192.973.754.535.005.62—帶速v(m/S)5101520253035401.00～1.010.000.000.000.000.000.000.000.000.000.00———1.02～1.040.070.140.210.280.340.410.480.650.800.98———1.05～1.080.140.280.410.550.640.830.971.291.611.95———1.09～1.120.210.410.620.831.031.241.451.952.402.92———1.13～1.180.280.550.831.001.381.651.932.623.213.90———E1.19～1.240.340.691.031.381.722.072.413.274.014.88———1.25～1.340.410.831.241.652.072.482.893.924.815.85———1.35～1.510.480.961.451.932.412.893.384.585.616.83———1.52～1.990.551.101.652.202.763.313.865.236.417.80———≥2.00.621.241.862.483.103.724.345.897.218.78———帶速v(m/S)510152025303540表8-10小帶輪的包角修正系數(shù)包角1180°175°170°165°160°155°150°145°140°135°130°125°120°110°100°90°10.990.980.960.950.930.920.910.890.880.860.840.820.780.740.69例8-1設(shè)計(jì)某機(jī)床上電動機(jī)與主軸箱的V帶傳動。已知：電動機(jī)額定功率P=7.5KW,轉(zhuǎn)速n1=1440r/min,傳動比i12=2,中心距a為800mm左右，三班制工作，開式傳動。解：計(jì)算項(xiàng)目計(jì)算與說明計(jì)算結(jié)果1.確定設(shè)計(jì)功率PC由表8-8取KA=1.3得：PC=1.3×7.5=9.75KWPC=9.75KW2.選擇帶型號根據(jù)PC=9.75KW，n1=1440r/min,由圖8-8選A型V帶選A型V帶3.確定小帶輪基準(zhǔn)直徑dd1由圖8-8、表8-4、表8-6取dd1=140mmdd1=140mm4.確定大帶輪基準(zhǔn)直徑dd2dd2=i12dd1=2×140=280mm由表8-4取dd2=280mmdd2=280mm5.驗(yàn)算帶速vv=πdd1n1/(60×1000)=3.14×140×1440/(60×1000)=10.55m/s5m/s<v<25m/s符合要求v=10.55m/s符合要求6.初定中心距a0按要求取a0=800mma0=800mm7.確定帶的基準(zhǔn)長度LdL0=2a0+π(dd1+dd2)/2+(dd2－dd1)2/4a0=2×800+π(140+280)/2+(280－140)2/(4×800)=2265.53mm由表8-2取Ld=2240mmLd=2240mm8.確定實(shí)際中心距aa≈a0+(Ld－L0)/2=800+(2240－2265.53)/2=787.24mm中心距變動調(diào)整范圍：amax=a+0.03Ld=787.24+0.03×2240=854.44mmamin=a－0.015Ld=787.24－0.015×2240=753.64mma=787.24mmamax=854.44mmamin=753.64mm9.驗(yàn)算小帶輪包角=169.81o1>120o合用1=169.81o合用10.確定單根V帶的額定功率P0根據(jù)dd1=140mm,n1=1440r/min由表8-7查得A型帶P0=2.27KWP0=2.27KW11.確定額定功率增量ΔP0由表8-9查得：ΔP0=0.17KWΔP0=0.17KW12.確定V帶根數(shù)z由表8-10查得：Kα≈0.98由表8-2查得：KL=1.06取z=4根Z=4根13.確定單根V帶的初拉力F0≈191.42NF0=191.42N14.計(jì)算帶對軸的壓力FQFQ＝2zF0sin(1/2)＝2×4×191.42sin(169.81/2)≈1525.31NFQ=1525.31N15.確定帶輪結(jié)構(gòu)繪工作圖（略）第五節(jié)同步帶傳動一、同步帶傳動的特點(diǎn)和應(yīng)用同步帶是以細(xì)鋼絲繩或玻璃纖維為強(qiáng)力層，外覆以聚氨脂或氯丁橡膠的環(huán)形帶。由于帶的強(qiáng)力層承載后變形小，且內(nèi)周制成齒狀使其與齒形的帶輪相嚙合，故帶與帶輪間無相對滑動，構(gòu)成同步傳動。如圖8-10所示。同步帶傳動具有傳動比恒定、不打滑、效率高、初張力小、對軸及軸承的壓力小、速度及功率范圍廣、不需潤滑、耐油、耐磨損以及允許采用較小的帶輪直徑、較短的軸間距、較大的速比，使傳動系統(tǒng)結(jié)構(gòu)緊湊的特點(diǎn)。一般參數(shù)為：帶速v≤50m/s；功率P≤100KW；速比i≤10；效率η=0.92~0.98；工作溫度－20~80℃。圖8圖8-10同步帶結(jié)構(gòu)與同步帶傳動二、同步帶的參數(shù)、類型和規(guī)格1.同步帶的參數(shù)(1)節(jié)距Pb與基本長度Lp。在規(guī)定張緊力下，同步帶相鄰兩齒對稱中心線的距離，稱為節(jié)距Pb。同步帶工作時保持原長度不變的周線稱為節(jié)線，節(jié)線長度Lp為基本長度（公稱長度），輪上相應(yīng)的圓稱為節(jié)圓。如圖8-10所示。顯然有Lp=Pbz。(2)模數(shù)m。與齒輪一樣，也規(guī)定模數(shù)m=Pb/。圖8-11圖8-11梯形齒和圓弧齒同步齒形同步帶分為梯形齒和圓弧齒兩大類，如圖8-11所示。目前梯形齒同步帶應(yīng)用較廣，圓弧齒同步帶因其承載能力和疲勞壽命高于梯形齒而應(yīng)用日趨廣泛。同步帶按結(jié)構(gòu)分為單面和雙面同步帶兩種型式。雙面同步帶按齒的排列不同又分為對稱齒雙面同步帶（DA型）和交錯齒雙面同步帶（DB型）兩種，如圖8-12所示。此外還有特殊用途和特殊結(jié)構(gòu)的同步帶。本節(jié)僅討論單面梯形齒同步帶。較常用的梯形齒同步齒形帶有周節(jié)制和模數(shù)制兩種，其中周節(jié)制梯形齒同步齒形帶已列入國家標(biāo)準(zhǔn)，稱為標(biāo)準(zhǔn)同步帶。標(biāo)準(zhǔn)同步帶按節(jié)距大小分為七種類型。帶的齒形和帶寬如表8-11所示，節(jié)線長度系列如表8-13所示。標(biāo)準(zhǔn)同步帶的標(biāo)記包括：型號、節(jié)線長度代號、寬度代號和國標(biāo)號。對稱齒雙面同步帶在型號前加“DA”，交錯齒雙面同步帶在型號前加“DB”。圖8-12對稱雙面齒和交錯雙面齒同步齒形帶標(biāo)記示例：圖8-12對稱雙面齒和交錯雙面齒同步齒形帶橡膠同步帶980H200GB/T11616-89帶寬代號200，帶寬50.8mm型號H,節(jié)距12.7mm長度代號980，節(jié)線長2489.20mm聚氨酯同步帶DA900H200GB/T11616-89帶寬代號200，帶寬50.8mm型號H,節(jié)距12.7mm長度代號900，節(jié)線長2286mm對稱齒雙面同步帶模數(shù)制梯形齒同步帶以模數(shù)為基本參數(shù)，模數(shù)系列為1.5、2.5、3、4、5、7、10，齒形角2為40°，其標(biāo)記為：模數(shù)×齒數(shù)×寬度。例如聚氨酯同步帶2×45×25表示：模數(shù)m=2,齒數(shù)z=45，帶寬bs=25mm的聚氨酯同步帶。三、同步帶輪(1)同步帶輪的材料及輪輻、輪轂結(jié)構(gòu)同V帶輪。為防止齒形帶工作時從帶輪上脫落，一般推薦小帶輪兩邊均有擋圈，而大帶輪則無擋圈；或大小帶輪均為單面擋圈，但擋圈各在不同側(cè)，如表8-12所示。(2)同步帶輪輪齒形狀有漸開線齒廓和直邊齒廓兩種（用于梯形齒同步齒形帶），其中漸開線齒廓的同步帶輪可借用齒輪刀具展成加工，齒廓具體尺寸請參閱有關(guān)手冊。(3)周節(jié)制同步齒形帶輪的寬度如表8-12所示，直徑如表8-14所示。(4)周節(jié)制同步帶輪標(biāo)記由帶輪齒數(shù)、帶型號、輪寬代號和標(biāo)準(zhǔn)代號組成。標(biāo)注示例：帶輪32H075GB/T11361-89輪寬代號075，輪寬19.1mm帶型號H,節(jié)距12.7mm輪齒數(shù)32表8-11周節(jié)制梯形齒同步齒形帶的齒形與帶寬型號節(jié)距pb(mm)齒形角2β(o)齒根厚s(mm)齒高h(yuǎn)t(mm)帶高h(yuǎn)(mm)齒根圓角半徑rr(mm)齒頂圓角半徑ra(mm)帶寬bS(mm)及代號MXL最輕型2.032401.140.511.140.130.13公稱尺寸3.04.86.4代號012019025XXL超輕型3.175501.730.761.520.200.30公稱尺寸3.04.86.4代號012019025XL特輕型5.080502.571.272.30.380.38公稱尺寸6.47.99.5代號025031037L輕型9.525404.651.913.60.510.51公稱尺寸12.719.125.4代號050075100H重型12.700406.122.294.31.021.02公稱尺寸19.125.438.1代號075100150公稱尺寸50.876.2—代號200300—XH特重型22.2254012.576.3511.21.571.19公稱尺寸50.876.2101.6代號200300400XXH超重型31.7504019.059.5315.72.291.52公稱尺寸50.876.2101.6代號200300400公稱尺寸127——代號500——表8-12周節(jié)制梯形齒同步齒形帶帶輪的寬度(GB/T11361－89)(mm)型號輪寬代號輪寬基本尺寸型號輪寬代號輪寬基本尺寸MXL0120190253.04.86.43.85.37.15.67.18.94.76.28.0H07510015020030019.125.438.150.876.220.326.739.452.879.024.831.243.957.383.522.629.041.755.181.3XXL0120190253.04.86.43.85.37.15.67.18.94.76.28.020050.856.662.659.60256.47.18.98.0XH30076.283.889.886.9XL0317.98.610.49.5400101.6110.7116.7113.70379.510.712.211.120050.856.664.160.4L05007510012.719.125.414.020.326.717.023.329.715.521.828.2XXH30040050076.2101.612783.8110.7137.791.3118.2145.287.3114.5141.5表8-13周節(jié)制梯形齒同步齒形帶的節(jié)線長度、齒數(shù)(GB/T11616-89)長度代號節(jié)線長Lp(mm)齒數(shù)z長度代號節(jié)線長Lp(mm)齒數(shù)z長度代號節(jié)線長Lp(mm)齒數(shù)zMXLXXLXLLXLLHXHHXHXXH3640444850566064707280889010011011212012413014015016017018018719020091.44101.60111.76121.92128.02142.24152.40162.56177.80182.88203.20223.52228.60254.00279.40284.48304.80314.96330.20355.60381.00406.40431.80457.20476.25482.60508.00455055606370758090100110125140155175200225250485664728088961041121201281441603035404550556065707580859095100334050210220225230240250255260270285300322328330345360367390420450480507510540560570600533.40558.80571.50584.20609.60635.00647.70660.40685.80723.90762.00819.15833.12838.20876.30914.40933.45990.601066.801143.001219.201289.051295.401371.601422.401447.801524.001051101151201251305660646872768086879298104112120128136144160485460667278849096102108114120586463066070075077080084085090098010001050110011201200125012601400154016001700175018001600.201676.401778.001905.001955.802032.002133.602159.002286.002489.202540.002667.002794.002844.803048.003175.003200.403556.003911.604064.004318.004445.004572.00126132140150160170180200210220250280340728088961121281441601762005664728096112128144表8-14周節(jié)制梯形齒同步齒形帶帶輪的直徑(GB/T11361-89)（mm）注：括號內(nèi)尺寸盡量不采用。四、同步帶傳動設(shè)計(jì)已知條件：①傳動功率；②小帶輪和大帶輪轉(zhuǎn)速；③傳動用途、載荷性質(zhì)、外廓尺寸、原動機(jī)種類以及工作制度等。設(shè)計(jì)計(jì)算步驟如表8-15所示。表8-15同步帶傳動設(shè)計(jì)計(jì)算項(xiàng)目符號公式及數(shù)據(jù)說明選擇帶型確定節(jié)距PcPc=KAPKA—工況系數(shù)，見表8-16P—傳遞的功率選擇帶型確定節(jié)距Pb根據(jù)Pc和n1由圖8—13查取帶型，表8-11確定節(jié)距Pb。為使傳動平穩(wěn)，提高帶的柔性以及增加嚙合齒數(shù)，節(jié)距應(yīng)盡可能取較小值。n1—小帶輪轉(zhuǎn)速。小帶輪齒數(shù)、節(jié)圓直徑z1d1z1≥zminzmin見表8-17d1=z1Pb/π帶速v和安裝尺寸允許時，z1盡可能選用較大值，并取表8-14中的標(biāo)準(zhǔn)值。大帶輪齒數(shù)、節(jié)圓直徑z2d2z2=iz1=z1n1/n2d2=z2Pb/πz2取表8-14中的標(biāo)準(zhǔn)值帶速vv=πd1n1/(60×1000)XL、L型，vmax=50m/s；H型，vmax=40m/sXH、XXH型，vmax=30m/s；若帶速超過上述范圍，應(yīng)重選d1初定中心距a00.7(d1+d2)≤a0≤2(d1+d2)或按結(jié)構(gòu)要求定帶的節(jié)線長及齒數(shù)Lp、zLp0≈2a0+π(d1+d2)/2+(d2-d1)2/4a0按表8-14取接近的標(biāo)準(zhǔn)值LP及其齒數(shù)z理論中心距a中心距可調(diào)時：a≈a0+(LP-LP0)/2中心距不可調(diào)時：a≈(d2-d1)/2cos(1/2)inv(1/2)=(LP-πd2)/(d2-d1)中心距a的偏差見表8-181為小帶輪包角。inv(1/2)為1/2角的漸開線函數(shù)。根據(jù)算出的inv(1/2)值，由漸開線函數(shù)表查得1/2值，即可求得精確的a值。d1=d2時，無法用漸開線函數(shù)，此時：a=Pb(z-z1)/2最好采用中心距可調(diào)結(jié)構(gòu)。續(xù)表8-15小帶輪嚙合齒數(shù)zm對MXL、XXL、XL型zmmin=4,其他型zmmin=6?；绢~定功率P0Ta—帶寬為bS0的許用工作拉力N,見表8-19。m—帶寬為bS0單位長度的帶的質(zhì)量kg/m見表8-19。帶寬bSbS0—選定型號的帶的基準(zhǔn)寬度mm,見表8-19。KZ—小帶輪嚙合齒數(shù)系數(shù)zm≥65432Kz1.000.800.600.400.20作用在軸上的力FR表8-16同步帶的工作情況系數(shù)KA工作機(jī)原動機(jī)交流電動機(jī)(普通轉(zhuǎn)矩鼠籠式、同步電動機(jī))直流電動機(jī)（并激），多缸內(nèi)燃機(jī)交流電動機(jī)（大轉(zhuǎn)矩、大滑差率、單相、滑環(huán)），直流電動機(jī)（復(fù)激、串激）單缸內(nèi)燃機(jī)每天運(yùn)轉(zhuǎn)時間,h3～58～1016～243～58～1016～24電傳打字機(jī)、計(jì)算機(jī)、復(fù)印機(jī)、錄音機(jī)、照相機(jī)、放映機(jī)、計(jì)測儀器、醫(yī)療器械1.01.21.41.21.41.6清掃機(jī)械、辦公機(jī)械、縫紉機(jī)、木工機(jī)械1.21.41.61.41.61.8輕載荷運(yùn)輸機(jī)、包裝機(jī)、篩子1.31.51.71.51.71.9液體攪拌機(jī)、食品機(jī)械、印刷機(jī)械、造紙機(jī)械、洗衣機(jī)、鉆床、車床、鏜床1.41.61.81.61.82.0攪拌機(jī)（水泥、粘性體）、帶式輸送機(jī)、紡織機(jī)械、銑床、刨床、磨床、振動篩、離心壓縮機(jī)、離心泵、齒輪泵、往復(fù)式壓縮機(jī)1.51.71.91.71.92.1懸掛式輸送機(jī)、洗衣機(jī)、離心鼓風(fēng)機(jī)、發(fā)電機(jī)、勵磁機(jī)、卷揚(yáng)機(jī)、起重機(jī)、橡膠機(jī)械、