Design of belt conveyor drive with cylindrical gear gearbox

Contents

Introduction

1 Purpose, principle of operation and characteristics of equipment

2 Equipment drive calculation

2.1 Kinematic calculation of equipment drive

2.2 Calculation of gear train

2.3 Preliminary calculation of shafts and approximate selection of bearings

2.4 Design dimensions of drive shaft of reduction gear box and wheel

2.5 Gearbox housing structural dimensions

2.6 Check of key connection strength

2.7 Calculation of open transmission

2.8 Selection of shaft coupling

2.9 Lubrication Material Selection

3 Gearbox assembly and actuator installation

3.1 Gearbox assembly

3.2 Installation of the drive

4 Safety precautions during equipment operation

Conclusion

List of used literature

Introduction

Belt conveyors are continuous machines in which the traction and bearing element is a flexible belt. The main purpose of this equipment is the mechanization of technological processes, increasing the pace of production, minimizing costs, improving the overall safety of work.

In the belt conveyor, the driving force of the belt is transmitted by friction transmission. (friction) when the belt is bent away, two drive drums, having an intermediate mechanism in the transfer body for decomposing the total movement from the drive motor to the drums with different angular speeds, are called differential, due to the rotation of the drive drum, the transport belt is constantly moving, moving the material and pulling it down when the belt bends one of the drums.

The purpose of the project is to design a belt conveyor drive with a cylindrical gear reduction gear

The design of the machine should be simple, strong, reliable and technological with maximum use of standard parts and unified assembly units, convenient for installation, dismantling and transportation, easy maintenance and repair, be economical in operation.

An important requirement for machines is their social fitness, that is, the ability to provide safe and favorable working conditions for service personnel. This includes the necessary stability against overturning under the influence of external loads, safety, fatigue of maintenance personnel during long-term continuous operation. The harmful effects of noise and vibration on humans should be limited. In addition, the operation of the machine should exclude its harmful effect on people working nearby and the surrounding nature.

2.8 Selection of shaft coupling

Chain coupling is used to connect reduction gear shaft with drum shaft.

Chain couplings have good compensating properties. Standard chains (single-row or two-row) are used as the connecting element of half-star; during installation and removal of these couplings, axial displacement of the units is not required.

The advantages of the chain coupling are: simplicity of construction and maintenance; reliability in operation; workability; small dimensions and weight.

The disadvantage is the presence of angular gaps and dead travel, as a result of which they cannot be used in reverse transmissions, as well as in the presence of large dynamic loads. [13]

Lubricant Selection

In mechanical engineering, the so-called crankcase system is widely used to lubricate gears. Oil is poured into the gear box housing 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 surfaces of the parts located inside the housing.

Crankcase lubrication is used at circumferential speed of gears and worms up to 12.5 m/s. At higher speeds, the oil discharges centrifugal force from the teeth and the engagement works with insufficient lubrication. In addition, power losses for mixing the oil significantly increase, and its temperature increases.

The choice of lubricant is based on the experience of the machines.

Oils are preferred. The principle of oil grade assignment is as follows: the higher the circumferential speed of the wheel, the lower the viscosity of the oil and the higher the contact stresses in the engagement, the greater the viscosity of the oil. Therefore, the required viscosity of the oil is determined depending on the contact voltage and the circumferential speed of the wheels. For the designed reduction gear, choose oil I-G-A -32 (industrial hydraulic oil without additives).

Plastic lubricants Litol24, TSIATIM-201, OKB 1227 are used to lubricate the bearings. [3]

Gearbox assembly and drive installation

3.1 Gearbox assembly

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

Assembly is performed in accordance with gearbox assembly drawing, starting from shaft assemblies.

Ball bearings pre-heated in oil to 801000C are fitted on the drive shaft. A key is put into the driven shaft and the gear wheel is pressed to rest against the shaft collar; Then spacer bushing is put on and ball bearings pre-heated 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 surface of the joint of the cover and the case with alcohol varnish. For alignment, a cover is installed on the body using two pins; bolts that attach the cover to the housing are tightened.

Prior to installation of through covers, felt seals impregnated with hot oil are put into grooves. By turning the shafts there is no jamming of bearings (the shafts must be rotated by hand) and the covers are fixed with screws.

Further, a key is laid on the end of the driven shaft in the key groove, a sprocket 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 housing and inspection hole is closed with cover with gasket. Cover is bolted.

Shafts of the assembled reduction gear must be rotated by hand without jamming.

The assembled gearbox shall be rolled and tested on the bench according to the program set by the specifications. [10]

3.2 Installation of the drive

During installation it is necessary to observe certain requirements of accuracy of position of one assembly unit relative to another, for example, electric motor and reduction gear box. To meet this requirement, drive mechanisms are installed on welded frames or cast plates. Frames are welded from sheet steel and shaped rolled stock - angles or channels. When welded frames are made from channels, they are arranged for convenience of bolts installation by flanges outside. Oblique washers (according to GOST 10906-78) are applied to the inner surface of the shelf or oblique straps are welded, which align the support surface under the bolt heads.

Support surfaces - plates on which gearboxes and electric motors are installed are created by welding narrow strips of steel with a height of

5n-6 mm.

In cases where the bolt passes through both flanges of the channel, stiffness is increased by ribs, elbows or tubes.

Since the frame is warped during welding, all support surfaces on which the drive mechanisms are installed are processed after welding.

Plate support surfaces shall be machined and separated from black (unprocessed) surfaces. Therefore, in these places, the wall thickness should be increased, providing for the necessary tides similar to the plates in the welded frames. [11]

Conclusion

As a result of the work, a belt conveyor drive was designed, consisting of a motor, a V-belt transmission, a cylindrical reduction gear box, and a chain coupling.

In the design, a full calculation was made for the belt conveyor drive, which includes: kinematic calculation, calculation of the gear and wheel sizes, calculation of permissible contact stresses, calculation of the axial distance, preliminary calculation of the gear box shafts, calculation of the dimensions of the gear box housing.

After the calculations, an electric motor, a coupling for connecting the shafts were selected, bearings and lubricants for the reduction gear were selected.

According to the obtained data, the kinematic diagram of the drive was made, the assembly drawing of the reduction gear was made, as well as the drawings of the shaft, the driven shaft and the gear wheel.

The course object was fully implemented in accordance with the task and recommendations for the design and content of the project.

The resulting drive meets the main requirements for the designed machines: reliability, operability, repairability, efficiency.

The goal of the project has been achieved.