Chain conveyor

Contents

1. Purpose, device and scope of drive gears

2. Selection of electric motor, breakdown of total gear ratio by stages, kinematic and power calculation

2.1.Election of electric motor

2.2.Difference of total gear ratio by stages, kinematic and power calculation

3. Calculation of open chain transmission

3.1.Compute drive roller chain

3.2.Construction of hub of smaller (driving) sprocket

4. Selection of materials, assignment of hardness, calculation of permissible stresses, calculation of geometric parameters and check calculations of gear gears by stresses and

4.1.Gearwheel materials and allowable stresses

4.2. Allowable contact stresses

4.3. Allowable bending stresses

4.4. Design calculation of low-speed stage of reduction gear box

4.5. Check calculation for strength of low-speed stage of reduction gear box

4.5.1.Compute by contact voltages

4.5.2. Calculation of teeth for bending strength

4.6. Design calculation of high-speed stage of reduction gear box

4.7. Check calculation for strength of high-speed stage of reduction gear box

4.7.1.Compute by contact voltages

4.7.2. Calculation of teeth for bending strength

5. Design calculation of drive shafts

6. Check calculation of shafts for fatigue strength

6.1. Check calculation of the driving shaft

6.2.Tandem Shaft Check Calculation

6.3. Check calculation of driven shaft

7. Calculation of bearings of all shafts for dynamic lifting capacity and durability

7.1.Compute the bearings of the drive shaft

7.2. Calculation of intermediate shaft bearings

7.3. Calculation of driven shaft bearings

8. Calculation of shaft-hub connections

9. Selection of couplings, check calculations of their parts

9.1.Elastic bushing-pin clutch

9.2.Frictional safety clutch

10. Assigning fits, surface finishes, selecting degrees of precision, and assigning feature control limits to surfaces

11. Description of lubrication, assembly and adjustment of gear box

11.1.Gearbox lubricant

11.2.Gearbox assembly

11.3.Adjustment of reduction gear box

12. Description and development of the wiring diagram

Literature

Purpose, device and application of drive gears

Drive serves for actuation of actuators. In this course project, the actuator is a chain conveyor. Drive consists of electric motor, reduction gear box and connection and safety couplings.

The electric motor converts electrical energy into mechanical energy, which through the drive elements is transmitted to the actuator, in this case, to the drive drum of the conveyor.

The motor shaft is connected to the drive shaft of the reduction gear by means of an elastic sleeve-flange clutch, which compensates for small inaccuracies in the location of the connected shafts. The coupling consists of a half-coupling in which steel pins are rigidly fixed, bearing rubber bushings, which enter the holes of the second half-coupling. Due to its properties, this coupling is called compensating. Such couplings are most preferred for connecting motors to reduction gears.

The reduction gear is designed to match the output parameters of the electric motor (speed and torque) with the required parameters of the actuator. This drive uses a two-stage cylindrical reduction gear with two helical gears. This arrangement of the reduction gear allows to reduce its dimensions along the length. Reduction gear reduces rotation speed and increases torque on output shaft relative to input shaft.

Drive sprocket of chain transmission is fitted on output shaft of reduction gear.

Gear gears have found applications in all branches of machine building and instrument making due to a number of their advantages: constant gear ratio; no slippage; high bearing capacity with relatively small dimensions and weight; long durability; operation in a wide range of loading modes; possibility of using loads reaching 5∙106 N∙m at circumferential speeds up to 150 m/s for transmission; the ability to transmit energy between shafts as desired in space; high efficiency (up to 0.995); relatively low loads on shafts and their supports; ease of maintenance and care. The disadvantages of gears include: high requirements for the accuracy of the manufacture of wheels and the assembly of gears and the need for increased rigidity of housings, supports, shafts; noise, especially at high speeds of rotation and insufficient strength; vibrations.

Cylindrical reducers are equipped only with cylindrical gears and differ in the number of steps and positions of shafts. Cylindrical two-stage reducers are usually made according to an expanded scheme bifurcated or coaxial with one or three power flows.

Calculation of open chain transmission

For open chain transmission transmitting torque from output shaft of reduction gear to shaft of conveyor, drive roller chain is selected.

Selection of couplings, check calculations of their parts

To connect the electric motor shaft with the drive shaft of the reduction gear, an elastic bushing-flange clutch (UVMP) (GOST 2142493) is used, consisting of a half-clutch, in which steel pins are rigidly fixed, which carry elastic bushings entering the hole of the second half-clutch. The clutch is quite sensitive to the displacement of shafts, although it allows radial displacements within the limits of 0.3... 0, 5 mm, angular - up to 1.50 and significant axial - up to 5 mm.

To prevent breakage of the teeth of the gear wheels and failure of the reduction gear due to excessive torque, a safety friction clutch is installed on the high-speed shaft. It consists of two half-couplings: driven and leading. Drive is connected to high-speed shaft by means of key joint. Driven half-coupling can slip along shaft and is made integral with drive gear of high-speed stage. Torque is transmitted from driving half-coupling to driven one by means of set of friction disks pressed to each other by peripheral springs. The pressing force can be adjusted by the required amount. When excessive torques appear, the frictions slip relative to each other and the engine continues to run idle.

Gearbox assembly

Prior to assembly, inner cavity of reducer housing is thoroughly cleaned and covered with oil-resistant paint. Assembly is carried out in accordance with the general view drawing of the reduction gear box, starting from the shaft assemblies:

- bearings pre-heated in oil up to 80100 ° C are put on the high-speed shaft, the coupling is installed and fixed ;

- a key is put into the intermediate shaft and the gear wheel is pressed, after which the gear is pressed through the remote bushing, and then bearings heated previously in oil are installed.

- keys are put into slow-moving shaft and gears, bearings heated previously in oil are installed, and then sprocket is pressed and fixed in axial direction.

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. Conical pins are used to base the cover relative to the body. After that, lubricant is put into bearing chambers, bearing covers are installed. By turning the shafts there is no jamming of bearings (the shafts must be rotated by hand) and the covers are fixed with screws.

Then plug of oil discharge hole with gasket and oil indicator are screwed in. Oil is poured into the housing and the inspection hole is closed with a cover with a cardboard gasket, the cover is bolted.

Gear box adjustment

The friction clutch is adjusted by the necessary tightening force of the nut pos.36 to obtain the necessary pressing force. The tightening force of the nut is controlled by size A. To prevent self-screwing of the nut, a locking washer pos. 45.