General purpose cylindrical helical gearbox design

Contents

INTRODUCTION

INPUT DATA

1. KINEMATIC AND POWER CALCULATION OF DRIVE

1.1. MOTOR SELECTION

1.2. KINEMATIC CALCULATION OF DRIVE

1.3. POWER CALCULATION OF DRIVE

2. GEARING CALCULATION

3. PRELIMINARY CALCULATION OF GEARBOX SHAFTS

4. GEAR AND WHEEL DESIGN DIMENSIONS

5. GEARBOX HOUSING STRUCTURAL DIMENSIONS

6. FIRST STAGE OF GEARBOX ASSEMBLY

7. SECOND STAGE OF GEARBOX ASSEMBLY

8. THIRD STAGE OF GEARBOX ASSEMBLY

9. CALCULATION OF KEYWAY CONNECTIONS

10. GEARBOX SHAFT CHECK CALCULATION

11. REFINED CALCULATION OF SHAFTS FOR FATIGUE STRENGTH

12. BEARING DURABILITY CHECK

13. HEAT CALCULATION OF GEARBOX

14. CHOICE OF OIL GRADE

15. SELECTION AND JUSTIFICATION OF GEARBOX MAIN PARTS FITS

16. GEARBOX ASSEMBLY

LIST OF LITERATURE USED

Introduction

A reducer is a mechanism consisting of gear or worm gears made in the form of a separate unit, and serves to transfer rotation from the shaft of the engine to the shaft of the working machine. Kinematic diagram of the drive

may include, in addition to the reduction gear, open gears, chain or belt.

The purpose of the reduction gear is to reduce the angular speed and, accordingly, increase the torque of the driven shaft compared to the driving one.

The reduction gear consists of a housing in which there are mechanical gears, shafts, bearings, etc.

The reduction gear is designed either to drive a certain machine, or according to a given load (torque on the output shaft) and gear ratio without specifying a specific purpose.

Gearboxes are classified according to the following main characteristics:

- transmission type (gear, worm, etc.);

- number of stages (single, two-stage, etc.);

- type of gears (cylindrical, conical, etc.);

- relative location of gear box shafts in space (horizontal, vertical);

- peculiarities of kinematic scheme.

Second stage of gearbox arrangement

Draw the gear and gear wheel according to structural dimensions found earlier, draw rolling bearings in section.

Between end faces of bearings and inner surface of housing there drawn are retaining rings. We install the rings on the diameters of the shafts for bearings. Let's take the thickness of the rings equal to 11.5 mm.

Draw bearing covers with sealing gaskets and bolts. Cover settings have been defined previously. The diameters of the covers are 110 mm and 120 mm for the driving and driven shafts, respectively.

Draw the drive and driven shafts of the reduction gear box.

The length of the connecting end of the driven shaft with a diameter of 30 mm is determined by the length of the coupling hub. Accept MUVP according to GOST 2142475 with a hub length of 58 mm.

Selection and justification of gearbox main parts fits

We assign the fits in accordance with the instructions [4, Table 10.13, p. 263]. Seat of the gear wheel on the shaft H7/p6 as per PT CMEA 144-75. Journals of shafts for bearings are made with deviation of shaft k6. Deflections of holes in the housing for external rings as per H7.

Gearbox assembly

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

The gearbox is assembled in accordance with the general view drawing, starting from the shaft assemblies:

- the drive shaft is fitted with retaining rings and bearings preheated in oil up to 80-100 ° C;

- key is put into driven shaft and gear wheel is pressed until stop against shaft collar;

spacer bushing, oil retaining rings are put on and bearings 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 the surfaces of the joint of the cover and the case with alcohol varnish. For alignment, a cover is installed on the body using two conical pins; bolts that attach the cover to the housing are tightened.

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 are placed. Prior to installation of through covers felt seals impregnated with hot oil are put into grooves. Rotation of shafts, absence of clamping of bearings are checked and covers are fixed with screws.

Further, a key is laid on the end of the driven shaft in the key groove, an asterisk is installed and fixed with an end attachment; the end attachment screw is locked with a special plate.

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; cover is bolted.

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

3.Сборочный чертеж. ТГТУ.140100.004.00.00 СБ.dwg

4.Деталировка. ТГТУ.140100.004 2Д.dwg