Cylindrical gearbox

Contents

Introduction

1 Selection of electric motor. Kinematic calculation of the drive

1.1 Initial data for the exchange rate project

1.2 Determination of rated power and rated frequency

motor rotation

1.3 Determination of gear ratio of the drive and its stages

1.4 Determination of power and kinematic parameters of the drive

2 Calculation of open transmission

2.1 Design calculation

2.2 Verification calculation

3 Calculation of closed gear train

3.1 Material Selection for Gear and Wheel

3.2 Determination of allowable contact stresses

3.3 Determination of allowable bending stresses

3.4Project calculation

3.5 Verification calculation

4 Preliminary calculation of gear box shafts and selection of bearings

4.1 Selection of shaft material

4.2 Preliminary selection of rolling bearings

5 Gear and Wheel Design Dimensions

6 Gearbox housing structural dimensions

7 First stage of gearbox arrangement

8 Serviceability check of bearings

9 Second stage of gearbox arrangement

10 Test of key joints strength

11 Refined shaft calculation

11.1 Check calculation of keys

11.2 Check calculation of shafts

12 Selection of fits for main parts of reduction gear box

13 Reduction gear box lubrication

14 Coupling selection

15 Gearbox assembly and adjustment

List of information sources

Introduction

The course "Applied Mechanics" reveals and explains the physical processes and phenomena associated with the work of assemblies and parts and the design of general-purpose parts and assemblies found in various mechanisms and machines.

A mechanism is a solid body system designed to convert the movement of one or more bodies into the required movements of other bodies (reduction gear box, gearbox, etc.).

A machine is called a set of mechanisms or devices that perform mechanical movements that serve to convert energy, materials or information in order to facilitate or replace the physical or mental labor of a person and increase his productivity.

The purpose of the course is to study the basics of calculating and designing general-purpose parts and assemblies, taking into account the mode of operation and the required resource of the machine. At the same time, the issues of material selection, method of thermal treatment, obtaining rational shape of parts, their processability and required manufacturing accuracy are considered.

The leading role of mechanical engineering among other sectors of the national economy is determined by the fact that the main production processes in all industries, construction and s/x are carried out by machines and mechanisms. One of the most widely used mechanisms is a reduction gear. A gearbox is a mechanism for reducing speed and increasing torque. Each reduction gear is characterized by transmitted power, gear ratio and torque on input or output shafts of reduction gear. The purpose of the reduction gear is to reduce the angular speed and increase the torque of the driven shaft compared to the driving one. The reduction gear consists of a housing in which transmission elements are placed - gears, shafts, bearings, etc. In some cases, lubricating devices or cooling devices are also arranged in the housing.

Depending on the type of gear wheels, cylindrical, conical, worm, wave, planetary reducers are distinguished.

Depending on the number of stages, there are single-stage, two-stage, three-stage reducers.

Selection of fits for gearbox main connections

We accept the following fits of the main conjugates [2, Table 10.13, p. 263]:

Gears, couplings 

Sleeves for rolling bearings in the housing

External rings of rolling bearings in the housing

Inner rings of rolling bearings for shaft

Oil retaining rings

Key groove in hub by width

Key groove on shaft by width

Key by height

Key width

Key by length

Key assembly in hub (width)

Key assembly on shaft (width)

Hole in the collar bearing cover

Section of shaft for sealing

Stars on the shaft

H7/r6,

H7/n6,

H7,

k6,

H7/f9,

JS9,

N9,

h9,

h9

h14,

JS9/h9,

N9/h9,

H8,

h11,

H7/h6.

Gearbox assembly

Prior to assembly, inner cavity of reducer housing is thoroughly cleaned and covered with oil-resistant paint.

Assembly is performed in accordance with gearbox assembly drawing, starting from shaft assemblies:

oil retaining rings and ball radial bearings 305 pre-heated in oil up to 80-1000C are put on the driving shaft;

a key of 10 × 8 × 30 is put into the driven shaft and the gear wheel is pressed until it rests against the collar of the shaft; Then, spacer bushing, oil retaining rings are put on and ball radial bearings 309 preheated in oil are installed.

The assembled shafts are laid in the base of the reduction gear case and put on the cover of the case, covering previously the surfaces of the joint of the cover and the case with sealant. For alignment, a cover is installed on the body using two pins; bolts with diameter M12 are tightened, which attach the cover to the housing.

After that, a spacer ring is put on the driven shaft, plastic grease is put into the bearing chambers, bearing covers with a set of metal gaskets for adjustment are placed.

Rubber reinforced cuffs are laid in grooves before installation of through covers. By turning the shafts do not lock the bearings (the shafts must be rotated by hand) and attach the covers with M8 bolts.

Further, a key 6 × 6 × 20 is laid on the end of the driving shaft in the key groove, an open gear asterisk is installed and fixed with an end attachment.

After that, a key 10 × 8 × 30 is laid on the end of the driven shaft in the keyway, a half-coupling is installed .

Then plug of oil discharge hole with gasket and iron oil indicator are screwed in. Oil is poured into the housing and the inspection hole is closed with a cover with a gasket made of technical cardboard, the cover is bolted.

The assembled gearbox is rolled and tested on the bench according to the program set by the specifications.