Design of worm single-stage gearbox - heading gear

Introduction

The course design consists of calculation and graphic parts.

The calculation part is drawn up in the form of an explanatory note and, depending on the volume and content of the project, may include the following sections:

1) Motor selection and kinematic calculation of the drive.

2) Calculation of belt, chain gear or open gear.

3) Gearbox gear design and check calculations.

4) Preliminary calculation of shafts.

5) Selection of bearings.

6) Serviceability check of bearings.

7) Refined calculation of shafts.

8) Selection and calculation of couplings, keys, bolts and other drive elements.

9) Thermal calculation of reduction gear (worm).

10) Reduction gear box lubrication.

11) Gearbox and drive assembly procedure.

12) Safety precautions.

The first five points make up the first stage of the gearbox layout and are the reference point of the course design schedule. To avoid errors, further design is possible only after phase I approval by the project manager.

The graphic part of the course project, as a rule, consists of 4 sheets of A1 format. This is:

1) General view of reduction gear box.

2) General view of the drive.

3) Parts and assembly units of reduction gear box and drive (in agreement with the course project manager).

Calculation of gears

Gears are calculated depending on operating conditions for contact or flexural strength. The main design parameter for closed cylindrical gears and worm gears is the axial distance determined on the basis of Hertz's theory. Calculation is performed for endurance by contact stresses. Open gears are calculated for endurance by bending stresses taking into account wear of teeth during operation. The main calculation parameter of open transmissions is the module.

Calculation of all transmission types starts with material selection and determination of permissible stresses.

Belt transmissions

Belt gear consists of driving and driven pulleys and belt fitted on pulleys with tension and transmitting circumferential force by means of friction. Transmissions with two or more slave pulleys are possible.

Belt transmissions have the main application:

a) for drive from electric motors of small and medium power of machine-guns;

b) for drive from primary engines (internal combustion) of electric generators, agricultural and other machines.

The most widespread in machines are wedge and flat belts. Flat belts are used as simplest, experiencing minimal bending stresses on pulleys; wedge - due to their increased traction ability.