Calculate and design a two-stage cylindrical coaxial gearbox with V-belt and chain gears

Contents

1 Introduction

2 Motor selection and kinematic calculation of the drive

3 Calculation of gears

3.1 Calculation of V-belt transmission

3.2 Calculation of cylindrical helical transmission of low-speed stage of reduction gear box

3.2.1 Selection of Gear Material

3.2.2 Determination of equivalent number of voltage change cycles

3.2.3 Definition of allowable contact stresses

3.2.4 Definition of permissible bending stresses

3.2.5 Allowable stresses for check of teeth strength during G-loads

3.2.6 Calculation of geometric parameters of transmission

3.2.7 Forces in engagement

3.2.8 Endurance test for contact stresses

3.2.9 Test calculation for endurance by bending stresses

3.2.10 Endurance check at G-loads

3.3 Calculation of cylindrical helical transmission of high-speed stage of reduction gear box

3.3.1 Selection of Gear Material

3.3.2 Determination of equivalent number of voltage change cycles

3.3.3 Definition of allowable contact stresses

3.3.4 Definition of permissible bending stresses

3.3.5 Allowable stresses to check bending strength of teeth

3.3.6 Calculation of geometric parameters of transmission

3.3.7 Forces in engagement

3.3.8 Endurance test for contact stresses

3.3.9 Endurance test for bending stresses

3.3.10 Endurance check at G-loads

3.4 Calculation of chain transmission

4 Calculation of shafts

4.1 Check calculation of drive shaft

4.1.1 Compilation of the calculation diagram

4.2.2 Determination of support reactions and construction of epures

4.1.3 Finding the shaft safety factor

4.2 Check calculation of intermediate shaft

4.2.1 Compilation of the calculation diagram

4.3.2 Determination of support reactions and construction of epures

4.2.3 Finding safety factor

4.3 Check calculation of driven shaft

4.3.1 Locating Forces in Engagement and Calculation Scheme

4.3.2 Determination of support reactions and construction of epures

4.3.3 Finding safety factor

5 Selection of bearings by dynamic lifting capacity

5.1 Calculation of driving shaft bearings

5.2 Calculation of intermediate shaft bearings

5.3 Calculation of driven shaft bearings

6 Selection and check calculation of key connections

6.1 Calculation procedure

6.2 Key under pulley

6.3 Key under high-speed gear wheel

6.4 Key under low-speed gear wheel

6.5 Key under sprocket

7 Gearbox housing sizing calculation

8 Gearbox assembly, adjustment and lubrication

List of literature

1 Introduction

A reduction gear is a mechanism consisting of gear or worm gears, made in the form of a separate element and serving to transfer rotation from the shaft of the engine to the shaft of the working machine.

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 use of gearboxes is due to economic considerations. The mass and cost of the engine at the same power decrease with an increase in its speed. It turns out that the use of high-speed downshift engines instead of a slow-speed engine without transmission is economically feasible. Asynchronous motors with a frequency of 750 and 1500 rpm are most widely used.

The reduction gear consists of a housing in which transmission elements are placed - gears, shafts, bearings, etc.

Gearboxes are classified according to the following main features: gear type (toothed, worm or gear-worm); number of stages (single-stage, two-stage, etc.); type of gears (cylindrical, conical, etc.); relative location of shafts in space (horizontal, vertical); peculiarities of kinematic scheme (unfolded, coaxial, with bifurcated stage, etc.). In this design, a two-stage cylindrical coaxial reduction gear is being developed.

Gears are the main type of gears in machine building. Their main advantages: high load capacity, and, as a result, small dimensions; high durability and reliability of operation; high efficiency; constant transmission ratio; possibility of application in a wide range of powers, speeds, transfer ratios. Disadvantages: noise during operation, inability to continuously change the gear ratio, insecurity during overloads, the possibility of significant dynamic loads due to vibration.

Bearings serve as supports for shafts. They receive radial and axial loads applied to the shaft and maintain a predetermined position of the shaft rotation axis. In this drive, ball radial thrust bearings are used that receive radial and axial loads in gear cylindrical gears.