Привод цилиндрическо- цепной. Общий вид редуктора на стадии «Технический проект». Рабочие чертежи на выходной вал редуктора, колесо цилиндрическое и крышка подшипника сквозная

Страницы работы

Фрагмент текста работы

Допускаемое напряжение при проверке зубьев на выносливость по напряжениям                                                                                                                                                                                                                                                                                                                                                                       

изгиба [sF]=s0Flimb/[SF] [1, c. 43]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 

По табл.3.9  [1] для стали 45 улучшенной при твердости НВ<350s0Flimb=1,8*HB                                                                                                                                                                                                                                                                                                                                                 

Для шестерни s0Flimb1=1,8*230=414 МПа                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 

для колеса s0Flimb2=1,8*200=360 МПа                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     

Коэффициент запаса прочности {SF}={SF}`{SF}``=1,75*1=1,75                                                                                                         =     1,75                                                                                                                                                                                                            

Для стали 45, термической обработке - улучшение коэффициент, учитывающий нестабильность свойств материала цилиндрического колеса [SF]=1,75 [1, табл.3.9];

полагая, что заготовки будут получены поковкой, коэффициент [SF]``=1

Допускаемые напряжения при расчете зубьев на выносливость:                                                                                                                                                                                                                                                                                                                                                                     

для шестерни  [sF]=414*1/1,75=236,6 МПа для  колеса [sF]=200*1,0/1,75=205,7 МПа                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                

Для шестерни отношение [sF]/YF1=236,6/3,8=54,1                                                                                                                                                                                                                                                                                                                               

Для колеса отношение [sF2]/YF2=205,7/3,6=57,1

Определим коэффициенты Yb и KFa

Yb=1-(b/140)=1-(10044`/140)=0,92

KFa=4+(ea-1)*(n-5)/(4*ea)=4+(1,73-1)*(8-5)/(4*1,73)=0,895

                                                                                                                                                                                                                                                                                                                                                                  

Дальнейший расчет ведем для зубьев колеса, так как полученное отношение для него меньше                                                                                                                                                                                                                                                                                                                                                

    sF2=736,3*1,36*3,6*0,92*0,895/(40*1)=49,8< 205,7  МПа.                                                                                                                                      

3. Расчёт открытой цепной передачи.

Из предыдущих расчетов известно: вращающий момент на валу меньшей звездочки

Т2=59,02*103 Н*м

Для уменьшения динамических нагрузок на цепь звездочки, а также диаметров звездочек принимаем приводную роликовую двухрядную цепь, расчетное значение шага которой определяем по формуле (6.26) [1]                                                                                                                                                                                                            

Для этого вначале находим:                                                                                                                                                                                                                                         рекомендуемое значение числа зубьев малой (ведущей) звездочки

z1=31-2u2=31-2*1,99=26,81, округлим полученное значение до целого z1=27                                                                                                                                                                                                                                                                                                                                                                                                                                     число зубьев ведомой звездочки  z2=z1u2=27*1,99=54                                                                                                                                                                                                                                                                                                                                                                                                               коэффициент эксплуатации по формуле [1, 6.27], принимая при спокойной нагрузке                                                                                                                                                                   kД=1                                                                                                                                                                                                                                                                                                                                                                                                                                           

kа=1 при аw=(30…50)t  при наклоне до 60 kн=1,

kсм=0,8 при смазывании погружением;                                                                                                                                                                                                                                                                                                                                                                                                                             

kсм=1 при непрерывной смазке ;

kп учитывает продолжительность работы в сутки;                                                                                                                                                                                                                                                                                                                                                                                                                                                  

kр =1,15 при периодическом регулировании натяжения цепи

kп=1,25 при двухсменной работе

Расчетный коэффициент нагрузки [1, c.241]

КэДкакНкрксмкп=1*1*0,8*1,25*1*1,15=1,15;                                                                                                                                                                                                                                                                                                                                                                                             ориентировочно принимаем допускаемое среднее давление [р]=20 МПа, число рядов цепи mр=2 [1, c.241]

Тогда расчетное значение шага цепи

Принимаем ближайшее стандартное значение шага t=15,875 [1, табл. 7.15]                                                                                                                                                                                                                                                                                                                                                                                    

Цепь 2ПР-15,875-45,4,  q=1,9 кг/м; Aоп=140

Cкорость цепи

v=z1tn1/60*103=27 *15,875*359/60*103=2,56 м/с                                                                                                                                                                                                                                                                                                                                                                                                                                       

Окружная сила F3/v=T3w3/v=106,2*18,84/2,56=780,45 Н                                                                                                                                                                                                                                                                                                                                                                                                                       

Проверяем давление в  шарнире

    р=FКэоп=780,45*1,25/ 140=17 МПа                                                                                                                                                                                                                                                                                                                                                                                                                                        

Уточняем  допускаемое давление [1, табл. 7.15]

[p]=18,7*{1+0,01(z1-17)}=18,7*[1+0,01(27-17)]= 20,6 МПа                                                                                                                                                                                                                                                                                                                                                                                                                                        условие р<[p]- выполнено

В этой формуле 24*0,85=18,7 МПа -табличное значение допускаемого давления по [1,табл.7.17] при n=359 об/мин  и t=15,875

Определяем число звеньев

Lt=2at+0,5zS+D2/at=2*50+0,5*81+4,272/50=141                                                                                                                                                                                                                                                                                                                                                                         

at=aц/t=50 [1, стр. 148] zS=z1+z2= 27+ 54=81  D=z2-z1/2p=4,27                                                                                                                                                                                                                                                                                                                                                                                

Уточним межосевое расстояние цепной передачи ац=0,25t{Lt-0,5zS+((Lt-0,5zS)2-8D2)1/2=776,8 мм                                                                                                                                                                                                                                                                                                                                                                                                                                                    

Для свободного провисания цепи предусматриваем возможность уменьшения межосевого расстояния на 0,4%, т.е. на 662*0,004=3 мм.

Диаметры делительных окружностей

dД1=t *z1/sin180 =15,875*27/sin180=134 мм                                                                                                                                                                                                                                                                                                                                                                                                                                             

dД2=t*z2/sin180/=15,875*54/sin180=266 мм                                                                                                                                                                                                                                                                                                                                                                                                                                            

Определим диаметры наружных окружностей звездочек.                                                                                                                                                                                                                                                                                                                                                                                                                                          

De1=t(ctg180/z1+0,7)-0,3d1=15,875(сtg180/ 27+0,7)-0,3*10,16=114 мм.                                                                                                                                                                                                                                                                                                                                                           

d1=10,16 мм- диаметр ролика цепи [1, табл. 7.15]

De2=t(ctg180/z2+0,7)-0,3d1=15,875(сtg180/54+0,7)-0,3*10,16=280 мм.                                                                                                                                                                                                                                                                                                                                                          

Силы действующие на цепь:

Окружная сила F=780,45 Н       от центробежных сил Fv=qv2= 1,9*2,562=12,5 Н                                                                                                                                                                                                                                                                                                                                                                                                                                   

q=1,9 кг/м [1, табл. 7.15] от провисания Ff=9,81kfqaц=9,81*1,5*1,9*0,777=21,72                        Н                                                                                                                                                                                                                                                                                                                                                 

kf=1,5 при угле наклона передачи 45 [1, с 151]

Расчетная нагрузка на валы

Fв=F+2Ff= 780,45+2*21,7=824 Н                                                                                                                                                                                                                                                                                                                                                                                                                                   

Проверяем коэффициент запаса прочности [1, c.243]

 s=Q/(FtцkД+Fv+Ff)=45,4/(780,45+12,5+21,7)=8,6                                                                                                                                                                                                                                                                                                                                                                   

Q=45,4 кН  [1, табл. 7.15 ]                                                                                                                                                                                                                                                                                                                                                                                                                                        

Это больше, чем нормативный коэффициент запаса [s]=8,4 [1, табл. 7.19]

условие s>[s]- выполнено

4. Предварительный расчет валов

Ведущий вал-шестерня.

Т1= 15,1  Н*м                                                                                                          

Зубья шестерни выполнены заодно целое с валом                                                                                                                                                                                                                                                                                                                                                                 

Диаметр выходного конца ведущего вала по расчету на кручение при [t]=15 МПа                                                                                                                                                                                                                                                                                                                                                      

 мм.                                                                                                                                                                                                                                                                                                                                                      

Округляем до ближайшего большего стандартного значения [1, с.161]                                                                                                                                                                                                                                                                                                                                                     

dв1=18 мм.

У подобранного электродвигателя [1, табл. П1] диаметр вала равен 28 мм.

Для обеспечения крутящего момента с вала двигателя на ведущий вал редуктора стандартной муфтой необходимо выполнить условие d`в1=(0,75…1,0)*dдв=(0,75…1,0)*28=21…28 мм

Для сопряжения вала редуктора с валом электродвигателя  выбираем стандартную муфту  МУВП ГОСТ 21424 с росточками полумуфт под dдв=28 мм и d1=25 мм                                                                                                                                                                                                                                                                                                                                                             

Диаметр под подшипником dп1=30 мм,                                                                                                           

Крутящие моменты в поперечных сечениях валов:                                                                                                                                                                                                                                                                                                                                                      

Ведомый вал.

Т2=59,02 Н*м                                                                                                                                                                                                                                                                                                                                                      

Диаметр выходного конца ведущего вала по расчету на кручение при [t]=15 МПа                                                                                                                                                                                                                                                                                                                                                      

 мм                                                                                                                                                                                                                                                                                                                           

Принимаем dв2=32 мм                                                                                                                                                                                                                                                                                                                                                       

Диаметры подшипниковых шеек dп2=35 мм                                                                                                                                                                                                                                                                                                                                            

Диаметр вала в месте посадки цилиндрического  колеса dк2=40 мм

Диаметр ступицы червячного колеса dст=1,6*dк2=1,6*40=64 мм                                                                                                                                                                                                                                                                                                                                                                                                               

Длина ступица lст=(1,2…1,5)dк2=(1,2…1,5)*40=48…60 мм

Толщина диска С=0,3*b2=0,3*40=12 мм

Толщина обода d0=(3…4)mn=(3…4)*1=3…4 мм

Принимаем значение равным d0=5 мм

5 Конструктивные размеры корпуса редуктора

Толщина стенок корпуса и крышки                                                                                                                                                                                                                                                                                                                                                         

d=0,04aw+2=0,04*100+2=4 мм.                                                                                                                                                                                                                                                                                                                                     

d1=0,032aw+2=0,032*100+2=3 мм.

Так как корпус и крышка редуктора выполняются литейным способом, о минимальная толщина отливок корпусов и крышек равно 8 мм , то рассчитанное ранее значение толщины стенок корпуса и крышки принимаем равным 8 мм.

Толщина фланцев (поясов)корпуса и крышки                                                                                                                                                                                                                                                                                                                                                   

b=1,5d=1,5*8=12 мм.                                                                                                                                                                                                                                                                                                                                            

b1=1,5d1=1,5*8=12 мм                                                                                                                                                                                                                                                                                                                                             

нижнего пояса корпуса р=1,5d=1,5*8=12,0 мм                                                                                                                                                                                                                                                                                                                                             

Диаметр болтов: фундаментных d1=(0,03…0,036)aw+12=(0,03…0,036)100+12=15…15,6 мм, принимаем болты с резьбой М16                                                                                                                                                                                                                                                                                                      

крепящих крышку к корпусу у подшипников d2=(0,7…0,75)d1=(0,7х0,75)*16=11,2…12,00 мм                                                                                                                                                                                                                                                                                                                                                             

принимаем болты с резьбой М 12                                                                                                                                                                                                                                                                                                                                                      

соединяющих крышку с корпусом d3=(0,5…0,6)d1=(0,5…0,6)*16,00=8…9,6 мм                                                                                                            

принимаем болты с резьбой М 8                                                                                                                                                                                                                                                                                                                                                         

6 Проверка долговечности подшипников

Ведущщий вал. Из предыдущих расчетов имеем Ft=736,3 H;                                                                                                                                                                                                                                             

                                                                             Fr= 272,6 Н  

                                                                            Fa=139,6 H.                                                                      

Из первого этапа компоновки  l1.1=61 мм, l1.2=38 мм, l1=99 мм                                                                                                                                                                                                                                                                     

Реакции опор:                                                                                                                                                                                                                                                                                   

в плоскости xz                                                                                                                                                                                                                                                                                         

                       Rх1=Ft*l1.2/l1=736,3*38/99=282,6 Н

     Rх2=Ft*l1.1/l1=736,3*61/99=453,7 Н                                                                                                                                                                                                                                          

в плоскости yz                                                                                                                                                                                                                                                                                        

                       Ry1=(Fr*l1.2+Fa*d1/2)/ l1=(272,6*38+139,6*39,7/2)/99=132,6 Н                                                                       

                       Ry2=(Fr*l1.1-Fa*d1/2)/2*l1=(272,6*61-139,6*39,7/2)/99=139,99 Н

Проверка : -Ry1+Fr-Ry2=-132,6+273-139,99=0                                                                                                                                                                                                                              

Суммарные реакции

 Н

Н                                                                                                                                                                                                                                                                                             

Как видно более нагружена вторая опора, следовательно расчет долговечности подшипников будем проводить по более нагруженной опоре2.

По формуле [1, стр117] эквивалентная нагрузка                                                                                                                                                                                                                                                                             

Р=(xvPr1+YFa)KbKT                                                                                                                                                                                                                                                               

В которой радиальная нагрузка Pr2=475 Н                                                                                                                                                                                                                                                                              

                            осевая Fa=139,6      Н                                                                                                                                                                                                                                                 

v=1, так как вращается внутреннее кольцо                                                                                                                                                                                                                                                                                

Kb=1,2 табл. [1, стр118] коэффициент безопасности                                                                                                                                                                                                                                                                     

КТ=1.0 табл. [1, стр118] температурный коэффициент          

Рассмотрим радиальный шариковый подшипник легкой серии 206 ГОСТ

Похожие материалы

Информация о работе

Тип:
Курсовые работы
Размер файла:
356 Kb
Скачали:
0