Belt Conveyor Drive Calculation

Contents

Contents

Introduction

1. KINEMATIC AND POWER CALCULATION OF DRIVE

2. CALCULATION OF GEARS

2.1 Calculation of high-speed stage

2.2 Calculation of intermediate stage

2.3 Calculation of slow-moving stage

3. GEARBOX ARRANGEMENT

4. CALCULATION OF SHAFTS

5. FITTING AND INSPECTION OF BEARINGS

5.1 High speed shaft

5.2 1st intermediate shaft

5.3 2nd intermediate shaft

5.4 Slow-moving shaft

6. CALCULATION OF KEY JOINTS

7. FITTING OF COUPLINGS

8. GEARBOX LUBRICATION

8.1 Lubrication of gear wheels

8.2 Lubrication of bearings

9. ECONOMIC JUSTIFICATION OF CONSTRUCTIVE DECISIONS TAKEN

List of literature

Introduction

In the modern conditions of the development of science and technology, the task of universal automation and mechanization of production becomes urgent. This is ensured by the use of various electrical drives of process equipment, main and auxiliary machines, mechanisms and complexes.

The electric drive is a complex complex mechanism containing a significant proportion of complex and critical parts, so the design of any drive should be accompanied by a thorough analysis and study at all stages: from the formulation of the technical specification, to the development of the technology for its manufacture and assembly.

The purpose of the course design is to create a belt conveyor drive structure comprising a three-stage reduction gear with a bifurcated intermediate stage. The efficient design of the units, parts, and, in general, the drive, the essence and methods of the solution set before the designer have the most significant influence on the technological, operational, ergonomic, aesthetic and, of course, functional characteristics of the product, and, therefore, on its cost.

Today, when the competitive market forces manufacturers to move to the highest quality and cheapest products, it is especially important to evaluate all aspects of design in order, even at the stage of its development, to avoid inefficient use of resources.

The author aims to design a reliable, high-quality and technological design of the belt conveyor drive in order to apply the acquired knowledge and skills in the course of studying general scientific and technical disciplines, as well as to understand how specific elements of the design of machine parts affect the entire life cycle of the product, its quality and competitiveness.

Kinematic and

power calculation of the drive

1.1 Determine the required drive power (kW) by formula (1.18) [1]:

Calculation of gears

2.1 Calculation of high-speed stage

We calculate the helical cylindrical transmission with the following initial data (see Table 1): torque on the wheel T2 = 16.81 Nm; wheel speed n2 = 711 min1; gear ratio U = 4.01; moderate load with short-term overloads.

2.1.1 We choose material of cogwheels from table 3.1 [1] GOST 454371 steel 40XH with a heat treatment combination: a gear wheel - training of 45...50 HRC; wheel - improvement of 269... 302 HB, αt = 750 MPa.

Gearbox Layout

For further calculations of the shafts and bearings of the reduction gear box, the first version of its layout is made. As you calculate parts and select their design shapes, the original layout can be refined.

The gearbox is arranged in accordance with the recommendations set out in [1, p. 80.81].

We accept the gap a between the inner surfaces of the reduction gear case and the rotating gear wheels in accordance with the recommendations [1, s.80] a = 10 mm.

Recommended distance between gearbox housing bottom and gearbox surface bo > 4a. We take bo = 41 mm.

Recommended clearance between gear end and inner surface of housing e1 = (1... 1.2) a. We accept e1 = 11 mm.

Recommended distance from bearing end to inner surface of reduction gear box housing, provided there are no oil protection and oil retaining rings e = 3... 5 mm. We accept e1 = 4 mm.

The layout drawing shall be 1:2 scale according to the sample shown in Fig. 3.17 [1].

Shaft calculation

4.1 Calculation of high-speed shaft

4.1.1 From Table 4.2 we select the material for shaft creation: Steel 45X GOST 454371,

5. Selection and inspection of bearings

5.1 High speed shaft

We choose the radial-thrust ball single-row bearing of the light series 36204 GOST 83175, since the shaft speed is more than. Parameters and characteristics: d = 25 mm; D = 52 mm; V = 15 mm; r=2,5; t=1,6.

1st intermediate shaft

We choose the radial-thrust ball single-row bearing of the light series 36206 GOST 83175. Parameters and characteristics: d = 20 mm; D = 47 mm; V = 14 mm; r=1,5; t=2.

5.3 2nd intermediate shaft

We choose the radial ball single-row bearing of the light series 210 GOST 833875. Parameters and characteristics: d = 25 mm; D = 52 mm; V = 15 mm; r=2,5; t=1,6.

Slow-moving shaft

We choose the radial ball single-row bearing of the light series 213 GOST 833875. Parameters and characteristics: d = 65 mm; D = 120 mm; V = 23 mm; r=2,5; t=5.

Check the correct selection of radial ball single-row rolling bearings at the following data: radial load on bearing I (left support A) Fr1 = 5548.73 N; radial load on bearing II (RH support B) Fr2 = 8966 N; axial load - no, shaft speed - 36 min1; internal diameter of bearing d = 65 mm; load variability for the entire bearing life is shown on the graph (see item 2.1 ).

Loading of bearings with moderate pushes to 150% from nominal, operating temperature does not exceed 100 wasps.

On the basis of recommendations [1, p. 132] we select bearings of light series No. 213 according to GOST 833875, in which dynamic lifting capacity Cr = 69400 N, static radial lifting capacity Cor = 45900 N.

5.4.1 Rotation factor at rotation of inner ring of bearing V = 1 [1, p. 135]; safety factor is determined as per Table 5.8 [1], for moderate tremors with short-term overloads up to 150% Kb = 1.4; temperature coefficient Kt = 1 at trab≤100oC.

Calculation of key connections

We check the selected key by crushing stresses.

7. Selection of couplings

To connect the electric motor shaft to the high-speed shaft of the reduction gear box, select the bushing clutch of the control and adjustment unit with the following parameters: d = 25 mm, D = 120 mm; half-coupling of the 1st version: L = 125 mm, l = 60 mm,,, B = 4 mm.

To connect the drive shaft to the slow-moving shaft of the reduction gear box, select the bushing clutch of the control and adjustment unit with the following parameters: d = 60mm, D = 220mm; half-coupling of the 2nd version: L = 226mm, l = 140 mm,,, B = 6 mm.

Reduction gear box lubrication

8.1 Lubrication of gears

Lubrication of gears and gearbox bearings significantly reduces friction losses, prevents increased wear and heat of parts, protects them from corrosion, and also slightly reduces noise during operation. Reducing friction losses increases the efficiency of the reduction gear.

We use crankcase lubrication for gear wheels of the reduction gear, in which the gear wheels dip into an oil bath poured into the housing. This lubrication is applicable at circumferential speeds in engagement up to 12 m/s .

Reduction gear wheels are lubricated using liquid lubricant - industrial oil.

According to the recommendations set out in [1, p. 230] for contact stresses αn up to 600 MPa and circumferential speeds of gears up to 5 m/s, the recommended kinematic viscosity of the oil should be (28... 33)· 106 m2/s at temperature t=50oC. Industrial oil I30A meets these requirements according to GOST 2079988, for which kinematic viscosity is 28· 106 m2/s.

Check of oil level in the gearbox housing is performed by means of rod oil indicator.

8.2 Lubrication of bearings

Lubrication of rolling bearings, in accordance with the recommendations set out in [1, p. 234], is carried out using plastic lubricant - Litol24 TU2-053-1747-85. Plastic lubricants are used to reduce lubricant consumption, improve sealing and facilitate maintenance of bearing assemblies.

To protect the high-speed shaft bearings from the washing out of plastic grease, jets and oil splashes from the reduction gear case, we use oil reflecting rings.

Economic justification of constructive decisions taken

When designing any machine or mechanism, special attention should be paid to the economic aspect - the cost of the finished product. In a modern market economy, the most important criterion for the implementation of any project is its competitiveness. However, it must be achieved not only by reducing the cost of the design of the machine, mechanism, but also by ensuring its high-quality and uninterrupted operation throughout the life of the product.

Therefore, in the detailed study and assessment of the entire life cycle of the product, from design to its disposal, it is necessary to take into account the most important economic factors, as well as to use advanced domestic and foreign experience .

Serial production plays a major role in the design of a unit or machine. Depending on this parameter, the design of the machine itself, as well as its parts and assemblies, can undergo significant changes.

The object of the course design is a belt conveyor drive, which includes a three-phase electric motor with a short-circuited rotor, a three-stage reduction gear, as well as coupling elements with elastic coupling.

The need to use the gearbox in the drive is dictated by the following considerations:

1) control of the rotation speed of the used electric motor, most often, is economically impractical, since outside the narrow and fixed nominal range of synchronous rotation speeds K.P.D. of the engine decreases significantly (many times);

2) The mass and cost of the electric motor at the same rated power with an increase in rotation speeds - decreases, therefore, the use of an electric motor with a synchronous rotation speed of n = 3000 min-1 in combination with a three-stage reduction gear that reduces angular speed, instead of an electric motor with a low rotation speed without a reduction gear is economically feasible.

The division of the gear ratio by stages using technically sound standards and methods leads to a minimum of its mass, and as a result, a decrease in metal consumption and final cost.

In the aspect of choosing a machine-building material, attention should be paid to inexpensive and widespread materials: for the case with a reduction gear, it is advisable to use cast iron, for shafts and gears - carbon structural or low-alloy steel, the mechanical properties of which, if necessary, can be improved by using appropriate heat treatment. When designing the shapes of gears, shafts and other parts, techniques should be used that reduce the material consumption of these parts. However, it is necessary to use the most technological design for the conditions dictated by modern production. When designing the gearbox, it is necessary to use the maximum number of unified and standardized parts, as this leads to a significant cheaper design overall, due to the large-scale and mass nature of their production.

Use of appropriate gear lubrication devices and reduction gear units that increase heat removal and uniform distribution and reduce friction; protection against corrosion (by painting the housing); application of high-quality sealing materials increases its durability.

However, during the design of the gearbox, a number of design flaws were also identified: the use of large module gears on slow-moving gear drives leads to a complication and an increase in the cost of their production process; the suboptimal procedure for breaking down the gear ratio by stages has led to an increase in its overall dimensions of metal consumption (especially in slow-moving gear); the use of shafts with a large fatigue margin also leads to inefficient metal consumption.

The excess of the fatigue strength margin is characteristic mainly for a high-speed shaft, to a lesser extent for a slow-speed shaft, to a minimum for intermediate shafts. This is due to the fact that the dimensions of the input and output shafts must be consistent with the set GOST for the corresponding types of couplings. Thus, it becomes necessary to increase the diametrical dimensions of the shafts, and, as a result, their high metal consumption and large stock ratios.

All the above-mentioned shortcomings are due to the lack of practical experience in designing such machines and will certainly be taken into account in further training and production activities.

List of literature

1. Course design of machine parts: Textbook/V.D. Soloviev, V.I. Fateev. - Tula: Publishing House of Tula State University, 2002. – 338 pages.

2. Course design of machine parts: Textbook/A.E. Sheinblit - M.: Vysch. shk., 1991. - 432 p.: il.