Расчет валов редуктора

1. Задание на курсовую работу

 

Рассчитать и спроектировать привод ленточного конвейера по схеме №51, применить тип редуктора №20.

 

 

 

Рисунок 1 – Схема привода

 

Исходные данные: Окружное усилие F=4,5 кН

Скорость ленты V=1,5 м/с

Ресурс =21000 ч.

Режим - IV

Тип производства- Единичная серия

Привод - 51

Редуктор – 20

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2. Введение

     В машиностроении находят широкое применение редукторы, механизмы, состоящие из зубчатых или червячных передач, выполненных в виде отдельного агрегата и служащих для передачи мощности от двигателя к рабочей машине. Кинематическая схема привода может включать, помимо редуктора, открытые зубчатые передачи, цепную или ременную

передачу.

    Назначение редуктора — понижение угловой скорости и повышение вращающего момента ведомого вала по сравнению с валом ведущим. Механизмы, служащие для повышения угловой скорости, выполнены в виде отдельных агрегатов, называют мультипликаторы.

     Конструктивно редуктор состоит из корпуса (литого, чугунного или сварного стального), в котором помещаются элементы передачи — зубчатые колеса, валы, подшипники и т.д.

     Редуктор проектируют либо для привода определенной машины, либо по заданной нагрузке (моменту на выходном валу) и передаточному числу без указания конкретного назначения.

     Привод предполагается размещать в закрытом, отапливаемом, вентилируемом помещении, снабженным подводом трехфазного переменного тока.

     В данной курсовой работе, привод состоит из электродвигателя, ременной передачи, цилиндрического редуктора, муфты и ленточного конвейера.

 

3. Расчет данных для ввода в ЭВМ
1. Выбор электродвигателя.

Для выбора электродвигателя определяем требуемую его мощность и частоту вращения.

Потребляемую  мощность привода (мощность на выходе) определяют по формуле: . А требуемая мощность находится: , где _,

 где

 

 

 

 

Частота вращения барабана определяется из формулы: :

,

где - диаметр барабана, который предварительно вычисляем из соотношения: =>          ,

где – ширина ленты конвейера, – число несущих прокладок ленты, из таблицы, данной в лекциях выбираем и , далее вычисляем диаметр барабана, который будет , принимаем диаметр равным

 

 

Находим момент, который необходимо приложить к  барабану:

 

Момент на выходе редуктора равен:

По требуемой  мощности подбираем двигатель мощностью  ,[стр.459[1]] т.к при подборе Р допускается перегрузка двигателя до 8% при постоянной и до 12% при переменной, у нас получается перегрузка .

Определим действительное фактическое передаточное число:

 

 

Окончательно  выбираем двигатель АИР 112М4:

Тип двигателя:      132М4/1440

Синхронная частота:     1500 мин^-1

Асинхронная частота:     1440 мин^-1

Мощность      7.5 кВт

     3.2 Расчет эквивалентного времени  работы

,

где L_hE – эквивалентное время работы;

L_h – ресурс, который нам задан;

K_HE – коэффициент эквивалентности, зависящий от режима нагрузки (режим нагрузки равен III), по таблице 2.4 [1].

Исходные данные для расчета на ЭВМ приведены  в таблице 1:

Таблица 1

T2T, Н×м	i	[sH]Б, МПа	[sH]Т, МПа	yba (Б)	yba (Т)	n, об/мин	Lhe, час	Код  передачи		Код  схемы  редуктора
								Б	Т
1148	22,61	840	900	0,28	0,35	1440	2625	2	2	20

 

 

 

 

 

 

4. Выбор наиболее оптимального варианта компоновки редуктора

   Условиями выбора оптимального  варианта компоновки редуктора  является наименьший объём конструкции  и минимальный вес.

                        

                Рисунок 2 – Схема конструкции редуктора

где - диаметр шестерни быстроходной ступени,

- диаметр колеса быстроходной  ступени,

- диаметр шестерни тихоходной  ступени,

- диаметр колеса тихоходной  ступени,

- ширина колеса быстроходной  ступени,

- ширина колеса тихоходной  ступени,

- межосевое расстояние.

 По данным компьютерной распечатки будем производить выбор оптимального варианта конструкции.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    

Условная  длина редуктор

 

1. L= 110+170+ = 446.285
2. L=115+170+
3. L=120+170+ = 446.005
4. L=130+160+ =434.175
5. L=140+160+ =441.055

Максимальный размер колеса

А=

1. А=
2. А=281.27+10.63+42.52=334.42
3. А=275.09+10.64+42.56=328.29
4. А=252.31+10.57+42.28=305.16
5. А=246.15+10.61+42.44=299.2

Ширина  редуктора

B=

1. В=24.8+51.8+2,5·10.63=103.175
2. В=27.6+46.2+2,5·11,20=108
3. В=30,6+50,9+2·10.63=100.375
4. В=31+42.4+2,5·10.64=100
5. В=33.7+44.3+2,5·10.57=104.425

Наименьшее  расстояние между колесом и корпусом

а=

1. а=
2. а=
3. а=
4. а=
5. а=

Наименьшее расстояние от основания корпуса до колеса

 

 

Объем корпуса редуктора

V=A·B·C

1. V= 340.6·103.175·465.545=0,0163
2. V= 328.29·100·467.285=0,0153
3. V= 305.16·104.425·455.315=0,0145
4. V=299.2·102.725·462.275=0,0142

Условная масса зубчатых колес

 

1. m=
2. m=
3. m=
4. m=
5. m=
6. График зависимости V и m от количества вариантов:

Рисунок 3 – График зависимости V и m от количества вариантов.

 

 

 

Выбор варианта

Руководствуясь  условием наименьшего объёма редуктора, а также наименьшей его массы, выбираем оптимальный вариант компоновки редуктора – вариант 3.

 

5. Статическое и кинематическое исследование редуктора.

      5.1  Определение вращающих моментов в зубчатых колесах с учётом потерь на трение.

                  Вращающий момент на выходном  валу редуктора:

Т_вых = 1148 Н·м,

                 Вращающий момент на колесе  тихоходной ступени редуктора:

Т_Т.В = Т_вых/h_п=1148/0,99=1159.6 Н·м,

Вращающий момент на шестерне тихоходной ступени редуктора:

Т_ш.т.ст= Т_Т.В/(U_Т×h_зп) =1159.6/(4,24×0,98) = 279.07 Н·м.

Вращающий момент на колесе быстроходной ступени редуктора:

Т_к.б.ст= Т_ш.т.ст/hп= 279.07/0,99 = 281.88 Н·м.

Вращающий момент на шестерне быстроходной ступени редуктора:

Т_ш.б.ст = Т_к.б.ст/(U_Б×h_зп) = 281.88/(5,5×0,98) = 52.3 Н·м,

                             Вращающий момент на входном  валу редуктора:

Т_вх  = Т_ш.б.ст/h_п,= 52.3/0,99=52.82·м.

 

 

 

5.2 Определение усилий в зацеплении.

 

 

                Рисунок 4 – Схема расположения усилий в зацеплении.

 

 

 

Усилия в быстроходной ступени с косозубым зацеплением:

 

Окружная сила на колесе:

 

Радиальная сила на колесе:

 

,где - угол зацепления

   -угол наклона линии зуба;

 

Осевая сила на колесе:

 

 

Усилия в тихоходной ступени  с косозубым зацеплением:

 

Окружная сила на шестерне:

 

 

Радиальная сила на колесе:

-угол наклона  линии зуба

 

 

          Направления усилий зацепления  показаны на Рисунке 4.

 

 

5.3 Кинематический анализ редуктора

 

Частоты вращения валов и зубчатых колес определяются частотой вращения электродвигателя и передаточными  числами зубчатых передач. 

Для быстроходного вала имеем:

n_Б = n_э = n_1Б = 1440 мин^–1;

Частота вращения промежуточного вала связана с частотой вращения быстроходного  вала соотношением

n_П = n_Б/U_Б = n_2Б = n_1Т,

где U_Б – передаточное число быстроходной передачи, U_Б = 5,5;

n_П = 1440/5,5 = 261.81 мин^–1;

Частота вращения тихоходного вала равна

n_Т = n_П /U_Т = n_2Т,

 

 

где U_T – передаточное число тихоходной передачи, U_T = 4,71;

n_Т = 261.81/4,24 = 61.75 мин^–1.

 

      Определим  угловые скорости вращения валов:

                         

 

     _{Тогда для соответствующих валов получаем:}