Course design "Cylindrical two-stage gearbox"

Contents

Introduction

1. Kinematic calculation of the drive

1.1 Drive diagram

1.2 Selection of electric motor

1.3 Clarification of transmission ratios

1.4 Kinematic and power calculation

1.5 Results Table

2. Calculation of gears

2.1 Gearing Diagram

2.2 Performance and calculation criteria

2.3 Selection of Gear Material

2.4 Calculation of permissible stresses

2.5 Design calculation of gears

2.6 Calculation of transmission 3-4 with spur wheels

2.7. Gearing calculation 1-

3. Preliminary Shaft Calculation

4. Design dimensions of gears

5. Structural dimensions of the housing

6. Bearing durability check

6.1. Calculation of high-speed shaft bearings

6.2. Calculation of intermediate shaft bearings

6.3. Calculation of low-speed shaft bearings

7. Selection and checking of keys

8. Refined Shaft Calculation

8.1. Shaft calculation

8.2. Shaft calculation

8.3. Shaft calculation

9. Coupling selection

10. Grease Selection

11. Gearbox assembly and adjustment

Conclusion:

List of literature used:

Project Description

The course project in the discipline "Machine Parts" contains:

- task sheet for the course project;

- three sheets of A1 format;

- two sheets of A3 format;

- an explanatory note on 62 sheets of format A4, including 17 figures, 8 tables and 110 formulas;

- specification on A4 sheets.

DRIVE KINEMATIC CALCULATION CYLINDRICAL GEAR SHAFT REDUCTION GEAR BEARING KEY GREASE

The purpose of the course design is to develop a belt conveyor drive including an electric motor, a gear reduction gear. This goal is achieved by developing a reduction gear box, selecting an electric motor, calculating gears, designing and checking key connections, bearings, developing a general type of reduction gear box, working drawings of parts of the output shaft, gear wheel, and cover of the reduction gear box housing.

When designing the explanatory note, Microsoft Word 2003 and the formula editor Microsoft Equation 3.0 were used to execute the graphic part - Compas3D (version 5.11.03).

Introduction

According to the task, it is necessary to develop a belt conveyor drive consisting of an electric motor, a two-stage cylindrical gear reduction gear.

It is required to select an electric motor, calculate gears, design and verify the suitability of key joints, bearings, develop a general view of the gear box, develop working drawings of parts: output shaft, gear wheel, cover of the gear box housing.

The electric motor is selected based on the required power and speed. Gearing is calculated according to the conditions of contact and bending endurance of teeth, checked for static strength. Shafts are designed from the condition of static strength (approximate calculation) and tested for endurance by safety factor.

The key connections are checked for crushing and the dimensions are taken depending on the diameter of the respective shaft section. The typical size of the coupling is determined based on the transmitted torque, speed of the shafts to be connected and operating conditions.

The shape and dimensions of the gearbox and drive frame parts are determined by structural and technological considerations, as well as the choice of materials and blanks.

When calculating and designing, the goal is to obtain a compact, economical and aesthetic design, which can be achieved using rational materials for gear parts, optimal selection of gear ratio, using modern design solutions, standard units and parts when designing a drive.

Structural dimensions of the housing

Housings of modern reducers are defined with flat surfaces, all protruding elements (bosses of bearing sockets, stiffening ribs) are removed from external surfaces and inserted into the housing, legs for attachment bolts in the base do not protrude beyond the dimensions of the housing, eyes for transportation of the housing are cast together with the housing. With this design, the body is characterized by great rigidity and better vibration acoustic properties, increased strength at the locations of the attachment bolts, reduced warpage during aging, the possibility of arranging a large volume of oil, simplifying external cleaning, and satisfying modern requirements of technical aesthetics. However, the mass of the case because of this increases somewhat, and the foundry equipment is complicated.

Refined Shaft Calculation

The refined calculation consists in determining the safety factor S for hazardous sections and comparing them with the required (permissible) stresses [S] = 1.5... 2.5. Strength is observed at S [S].

We will calculate for the suspected dangerous sections of each of the shafts.

Grease Selection

A crankcase system is widely used to lubricate the gears. Oil is poured into the reduction gear case so that wheel rims are immersed in it. When rotating, the wheels entrain the oil, spraying it inside the body. Oil enters the inner walls of the housing, from where it flows into its lower part. Inside the housing, a suspension of oil particles is formed in the air, which covers the surface of the parts located inside the housing. Oil is poured inside the housing to the level of the immersion wheel by about 1/3. volume of the oil bath 4... 6 l.

Bearings are lubricated with the same oil as gear parts. When the wheels are lubricated by immersion, the bearings receive a splash of oil flowing from the wheels, shafts and walls of the housing.

As per Table, oil viscosity is established. At contact voltages up to 600 N/mm2 and a speed of V up to 2 m/s, the recommended oil viscosity should be approximately 34 mm2/s. According to the table, industrial oil I-G-A-32 is taken from reference literature (Table 11.111.3, p. 200 ,/4/).

Check of oil in the reduction gear box housing is performed by means of the lamp oil indicator.

Gearbox assembly and adjustment

Prior to assembly, reduction gear case cavity is cleaned and covered with oil-resistant paint. The gearbox is assembled in accordance with the general view drawing.

Bearings pre-heated in oil up to 80 - 100˚S are fitted on input shaft.

Keys are laid on intermediate shaft and gears are pressed. They dress rings. Then bearings preheated in oil to 80 - 100˚S are fitted. A clearance of 0.5 mm is maintained between the end face of the bearing and the end face of the ring for adjustment.

A key is put on the output shaft and the gear wheel is pressed until it rests against the shaft collar, I dress rings, bearings are fitted, previously heated in oil up to 80- 100˚S.

Shafts are installed in housing. For alignment, the reduction gear cover is installed on the housing with the help of conical pins, bolts are tightened, which attach the reduction gear cover to the housing.

Keys are laid on cylindrical shanks of inlet and outlet shafts.

Plug of oil discharge hole with gasket is screwed in and oil indicator is installed. Oil is poured into the housing and the inspection hole is closed with a cover with a gasket, fixing the cover with screws.

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

Conclusion:

1. According to the task, a drive was developed - a cylindrical two-stage reduction gear.

2. An electric motor was chosen, gear gears were calculated, key joints, bearings were designed and tested for suitability, a general view of the reduction gear was developed, working drawings of parts were developed: output shaft, gear wheel, bearing covers and sprocket.

3. The electric motor was selected based on the required power and operating conditions of the drive.

4. The key connections were checked for crumpling. Bearing suitability was assessed by static and dynamic lifting capacity.

5. The shape and dimensions of the parts of the reduction gear and drive plate were determined by structural and technological considerations, as well as the choice of materials and blanks.