Chain conveyor drive with worm gear

Contents

Contents

Introduction

1 Selection and check of electric motor

1.1 Required electric motor power

1.1.2 Required motor speed

1.1.3 Electric motor selection

1.2. Determination of total gear ratio and its breakdown between stages

1.2.1 Total gear ratio of the drive

1.2.2 Breakdown of total gear ratio by drive stages

1.3 Determination of rotation speeds of drive shafts

1.4 Determination of angular speeds of drive shafts

1.5 Determination of power on drive shafts

1.6 Determination of torque on drive shafts

2 Worm Gear Calculation

2.1 Material selection and definition of allowable stresses

2.2 Thermal calculation of worm gear box

2.3 Preliminary determination of main transmission parameters

2.4 Adjustment of preset parameters

2.5 Efficiency factor

2.6 Force in engagement of worm pair

2.7 Circumferential force on wheel and axial force on worm

2.8 Bending stress in worm gear teeth

3 Calculation of open cylindrical spur gear

3.1 Initial data for calculation

3.2.1 Selection of Gear Materials

3.2.2 Average hardness of gear and wheel material

3.2.3 Number of gear and wheel stress change cycles

3.2.4 Equivalent number of change cycles

3.2.5 Maximum allowable stresses

3.2.6 Determining the number of teeth and refining the gear ratio

3.2.7 Determination of gears dimensions and engagement parameters

3.2.8 Basic geometric parameters of transmission

4 Approximate calculation of shafts

5 Design calculation of shafts and gearbox layout

5.1 Design calculation of gear box shafts

5.1.1 Design calculation of speed shaft of reduction gear box

5.1.2 Design calculation of low-speed gear box shaft

5.2 Preselection of bearings

5.3 Main dimensions of bearing covers

5.3.1 Main dimensions of high-speed shaft bearing covers

5.3.2 Main dimensions of low-speed shaft bearing covers

5.4 Selection of collars to be inserted into through bearing covers grooves

5.5 Main dimensions of worm gear

5.6 Gearbox housing structural dimensions

6 Check calculation of key joints

6.1 Check calculation of key connection at output end of speed shaft of reduction gear box

6.2 Check calculation of the key connection under the wheel on the low-speed shaft of the reduction gear box

6.3 Check calculation of key connection at output end of low-speed gear box shaft

7 Coupling selection and check calculation

8 Lubrication selection

9 Gearbox Assembly Procedure

Summary

The course work is devoted to the development of the design of the worm reduction gear with a vertical shaft and the working drawing of one of the parts of the worm reduction gear .

The purpose of the course work is the theoretical study of the basics of calculation and design of parts and assemblies of general machine-building applications, taking into account their fulfillment of the given functional purpose, requirements of accuracy, processability and reliability, solving engineering problems, developing creative abilities. The work describes the main elements and the principle of operation of the worm gear box .

The results of kinematic and power calculations of the drive are given in the work; sizing of all mechanical gears; check calculation of key connections, as well as sketch layout of reduction gear box, selection of coupling, lubrication and shaft supports.

The explanatory note contains pages 30 of the main text, including 3 tables, 5 sources of used literature. Graphic part is executed on 1 sheet A1 and 1 sheet A3.

Introduction

In mechanical engineering, various drive designs are widely used. A drive is an electric power device that drives a machine or mechanism. Drive consists of power source, transmission mechanism and control equipment. The source of energy is a motor (thermal, electrical, pneumatic, hydraulic, etc.) or a device that gives back previously stored energy (spring, inertial, weight mechanism, etc.). A gearbox is usually an important part of the drive. 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. A reduction gear is a mechanism consisting of gear or worm gears, made in the form of a separate unit and serving to transfer rotation from the shaft of the engine to the shaft of the working machine. The kinematic drive circuit may include, in addition to the gearbox, open gears, chain or belt gears.

The purpose of this work is to calculate the drive of a chain conveyor consisting of an electric motor, a worm reduction gear with a vertical slow-moving shaft and a cylindrical open gear. The calculation and design of the gear box involves the determination of geometric and structural dimensions of individual parts, the development of their structures. Based on the experience of creating such devices and current standards, recommendations are given for determining the gear ratios of each gear, selecting materials for gears and shafts, checking parts for strength, developing a sketched arrangement of a reduction gear, designing a housing, gears, shafts, bearing covers, and selecting bearings and keys.

Main dimensions of bearing covers

Calculations are carried out according to [4, c.196197].

We make all covers screwed.

5.3.1 Main dimensions of high-speed shaft bearing covers

Diameter of external bearing ring D = 80 mm, hence:

- wall thickness δ = 6 mm;

- diameter of bolts is d = M8;

- their number - Z = 4;

- flange thickness δ1 = 7 mm;

5.3.2 Main dimensions of low-speed shaft bearing covers

The diameter of the outer bearing ring D = 100 mm, hence:

- wall thickness δ = 7 mm;

- diameter of screws is d = M10;

- their number - Z = 6;

- flange thickness δ1 = 8 mm;

Selection of collars to be inserted into through bearing covers grooves

In the through cover of the high-speed shaft bearing we insert the cuff 1.135x581 GOST 875279 [5, s.398, Table K20], and in the through cover of the low-speed shaft bearing we insert the cuff 1.150x701 GOST 875279 [5, p. 398, Table K20].

Gearbox Assembly Order

Prior to assembly, inner cavity of housing is thoroughly cleaned and covered with oil-resistant paint. The reduction gear is assembled in accordance with the assembly drawing of the worm reduction gear. Assembly is started by putting ball radial thrust bearings 66307 on the worm shaft, preheating them in oil to 801000C. Assembled unit of worm shaft is inserted into cover-sleeve of reduction gear case.

At the beginning of assembly of the worm wheel shaft assembly, the key 18 × 11 × 90 is laid and the worm wheel is pressed until it rests against the shaft collar; then roller conical bearings, also heated in oil, are installed. Assembled shaft is installed in base of housing and cover of housing is installed .

Rubber cuffs are put into bearing through covers and covers with gaskets are installed.

To adjust the worm engagement, the entire worm wheel shaft set must be axially displaced until the middle plane of the wheel coincides with the worm axis.

Oil outlet plug with gasket and oil indicator are screwed in. Oil is poured into reducer and inspection hole is closed with cover with perfume.

The assembled gearbox is rolled and tested on the bench.

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