Calculation of belt conveyor drive

Contents

Contents

Task

Introduction

1 Motor calculation and selection

2 Material Selection

3 Low-speed stage calculation

4 Calculation of high-speed stage

5 Execution of the layout drawing

6 Calculation of shafts for strength

7 Determination of shaft safety factor

8 Selection of rolling bearings

9 Determination of main dimensions of the housing and gearbox cover

10 Calculation of flat-time transmission

11 Selection of keys

12 Selection of part fits

13 Lubrication selection

14 Coupling selection

15 Gearbox assembly procedure

List of literature

Introduction

It should be noted the special role of course design on "Machine Details and Design Fundamentals" in introducing students to the activities of engineers and researchers, in understanding the importance of general theoretical and general engineering disciplines.

The course project contributes to the consolidation, deepening and generalization of knowledge and the application of this knowledge to the complex solution of a specific engineering problem in the design of machine parts.

Currently, the machines and mechanisms are driven mainly by AC motors at a speed of 750 to 3000 rpm. However, machine tools in most cases have a small rotation speed n = 20100 rpm (drum, winches, belt conveyor drive drum, etc.) or a higher rotation speed than that of an electric motor.

To convert rotary motion of electric motor to shaft of working member, mechanical gears are used designed to perform a whole range of other functions, the main of which are:

increasing or decreasing torque;

Change the path or nature of the motion

speed control and change;

protection of machine parts and assemblies from breakage during G-loads.

In this course design, the belt conveyor drive is developed, consisting of the main working units: electric motor, coupling, reduction gear box, drum, support, drive base.

Grease Selection

Currently, the simplest method is widely used in machine building for lubricating gears - immersion of gears in a bath with liquid oil, the so-called crankcase grease.

The maximum permissible depth of immersion of the wheels in the oil bath is due to the minimum cost of mixing and spraying oil. In conical cylindrical reducers, the oil level in the bath should provide lubrication of the teeth of the conical wheels along the entire length of the tooth and to its entire height. It is desirable to use high viscosity oil to increase the resistance of the teeth against jamming.

The most favorable operating conditions of the general purpose rolling bearings of the reduction gears are created when they are lubricated with oil mist created by spraying oil with rotating gear wheels. At the same time, heat is removed well, the bearing is cleaned from wear products, and there is little resistance to rotation.

Oil bath volume is taken at the rate of 0.5 dm3 per 1 kW of transmitted power Vm = 0.5 2.6 = 1.3 dm3. Bearings are lubricated with the same oil by spraying.

The viscosity of the oil is selected depending on the circumferential velocity, load and material of the teeth. In high-speed steam V = 2.24 m/s at recommended viscosity of oil cSt; low-speed V = 1.078 m/s with recommended oil viscosity

FST. Average value of cSt. On the recommendation of literature [6] we choose aviation MS-20 oil.

14 Coupling selection

The type of coupling is selected according to the requirements of the drive device.

The dimensions of the couplings depend on the torque to be transmitted. When selecting standard couplings, the diameter of the shaft ends, which they must connect, is also taken into account.

On the driven shaft, on the basis of the recommendation in the literature, we put an elastic bushing sleeve clutch with a nominal torque of 500 N m.

Gearbox Assembly Order

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

Assembly is carried out in accordance with the general view drawing of the reduction gear box, starting from the shaft assemblies:

- oil retaining rings and ball bearings pre-heated in oil to 80100 ° C are put on the driven shaft;

- a key 12x8x25 is put into the driven shaft and the gear wheel is pressed to rest against the shaft collar, then a spacer bushing, an oil retaining ring are put on and ball bearings heated in oil are installed;

- intermediate shaft assembly is performed similarly.

The assembled shafts are laid in the base of the reduction gear case and the cover of the case is put on, the surface of the joint of the cover and the case is previously covered with alcohol varnish.

For alignment, a cover is installed on the housing with the help of two conical pins, bolts are tightened, which attach the cover to the housing .

After that, a spacer ring is put on the driven shaft, plastic lubricant is put into the bearing chambers, a bearing cover with a set of metal gaskets is placed, and thermal clearances are adjusted. Before installation of through covers gland seals are put into grooves. The shafts are checked for weldability, absence of bearings jamming and the covers are fixed with screws.

Then key is put into key groove on end of driven shaft, pulley is installed and fixed by end fastener. The end attachment screw is locked with a special bar.

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

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