Heading work on parts of "Worm gear" machines with explanation

Contents

1. ENERGY AND KINEMATIC CALCULATION OF THE DRIVE

2. WORM GEAR CALCULATION

3. CALCULATION OF CHAIN TRANSMISSION

4. SHAFT CALCULATION

5. BEARING CALCULATION

6. CALCULATION OF SHAFT-HUB CONNECTIONS

7. FITTING OF COUPLINGS

8. SELECTION AND JUSTIFICATION OF LUBRICATION METHOD OF GEARS AND BEARINGS

LIST OF LITERATURE USED

Energy and kinematic calculation of the drive

1.1. Source Data

Depending on the purpose of the drive, the initial data are combined into three groups:

a) to drive belt conveyors

Ft - circumferential force on the drum, kN ;

V - belt speed, m/s;

Dδ - drum diameter, m.

b) to drive chain conveyors

Ft - circumferential force on the sprocket of the chain conveyor , kN;

V - chain speed, m/s;

Z is the number of sprocket teeth;

Rv - pitch of traction sprockets, mm.

c) for other general purpose conveyors and drives

Tv - torque on the conveyor drive shaft, N * m;

nfan - speed of drive shaft rotation, min-1.

Initial data for this drive:

TV - 1800 N * m;

[omega] - 8 s-1;

t - 4 incl.

Worm Gear Calculation

2.1. Source Data

T1 = 59.5 - torque on a worm, N * M;

T2 = 951.7 - wheel torque, N * M;

n1 = 2910 - worm speed, min 1;

n2 = 145.5 - wheel speed, min. 1;

u = 20 - gear ratio;

t = 8000 - transmission service life, hours

Calculation of chain transmission

By the nature of the work performed, the circuits are divided into traction and drive.

Bushing (IR), roller (RR) and toothed (RR) chains are used as drive chains.

Bushing chains are manufactured with a pitch of 9.525 mm and are used only in motorcycles and cars (drive to the camshaft).

Drive gear chains allow high speed and above-mentioned strength, but are more difficult to manufacture and very metal-intensive, so they are rarely used.

Roller chains were most used in drives, the calculation of which is discussed below.

3.1. Source Data

P2 = 14.5 - transmitted power, kW;

T2 = 951.7 - torque on the leading asterisk, N * M;

n2 = 145.5 - drive sprocket rotation speed, min 1;

u = 2 - gear ratio;

ψ ° = 45 ° - a chain tilt angle to the horizon

3.3. To Assign a Preliminary Circuit Step

When assigning a chain pitch, the speed of the small sprocket must be taken into account. It is advisable to assign the pitch of the chain in the first approximation of 25.4 mm. For the selected step, the allowable value of the average pressure in the hinges [po] = 32 MPa is determined .

Shaft calculation

4.1. Materials and heat treatment of shafts

The main materials for shafts and axles are carbonaceous and alloyed steels, due to their high mechanical characteristics, hardenability and ease of production of cylindrical billets by rolling.

For the manufacture of medium-voltage, medium-speed shafts, 45, 40X steels are used, subject to improvement.

Highly stressed shafts produce from alloyed staly 40XH, 40XH2MA, 30HGT, 30HGSA, etc. The shafts of these steels are usually improved, quenched with high tempering or surface quenching with HF heating and low tempering (splined shafts).

The high-speed shafts rotating in bearings of sliding and demanding the high hardness of pins produce from cemented staly 20X, 12HNZA, 18HGT or nitrated staly type 38H2MYuA.

Bearing calculation

5.1. Select Bearing Type

In accordance with the established practice of designing and operating machines, the bearing type is selected according to the following recommendations. Ball radial bearings are most often used to support shafts of spur and helical gears of gears and gearboxes.

Initially, light series bearings are used. If in the subsequent calculation the life of the light series bearing is insufficient, the middle series bearings are accepted. With excessively large sizes of ball bearings, tapered roller bearings are used.

Conical and worm wheels shall be precisely and rigidly fixed in axial direction. Ball radial bearings have low axial rigidity. Therefore, conical roller bearings are used in power transmissions for shaft supports of conical and worm wheels. Initially, a light series is selected.

Select roller cone bearing 7214.