Machine Parts Course Design: "Conveyor Drive Design"

Contents

1. Electric motor selection

2. Determination and breakdown of total gear ratio

by stages

3. Determination of power, torque and speed 2 for each shaft

4. Calculation of gears

5.Excise Shaft Design

6. Calculation of bearings

6.1.Selection of bearing type

6.2. Calculation of bearings on the intermediate shaft

6.3. Calculation of bearings on low-speed shaft

6.4. Calculation of bearings of drive shaft

7. Low Speed Shaft Calculation

7.1 Design Diagram

7.2. Static Strength Calculation

7.3. Fatigue resistance calculation

8. Calculation of connections

8.1 Keyway connections

8.2. Key connection of wheel with intermediate shaft of reduction gear box

8.3. Key on motor shaft

8.4. Key on slow-moving shaft

9. Calculation of couplings

9.1. Calculation of elastic element

9.2. Calculation of elastic-compensating coupling

10. Contents

Bearing calculation

6.1.Selection of bearing type

Ball radial bearings are adopted for cylindrical gear supports.

Often, shaft supports are placed not in one, but in different housings. In our case, these are the supports of the drive shaft. Housings accommodating bearings are mounted on conveyor frame. Since errors in the manufacture and assembly of the parts are inevitable, this leads to skew and displacement of the axes of the mounting holes of the bearing bodies relative to each other. In addition, in the working gear, under the influence of loads, the shaft is deformed. In the design of the drive shaft, due to the uneven distribution of load on the elevator buckets, shaft distortions and uneven loading of the shaft supports inevitably occur.

All of the above makes it necessary to use spherical bearings in such units, which allow significant distortions.

Due to the relatively large long shaft and significant assembly errors, the shafts are fixed from axial displacements in one support. Therefore, the ring of the other bearing must have freedom of displacement along the axis, for which, at both its ends, clearances 3... 4 mm are left. In the first support, these clearances must be eliminated by means of bushings. If you do not follow these recommendations, when both supports are fixed in the axial direction and the shaft is inevitably deflected, the bearing rolling bodies will deform, which may cause the assembly to wedge.

Calculation of connections

8.1 Keyway connections

Key connections are used to transfer torque from the wheel to the shaft. Most often, prismatic and segment keys are used. In all key connections, in this case, prismatic keys were used during design, since the diameters of the shafts are small, and the use of segment keys is not allowed due to deep slots for them. Keyboards are calculated based on the crushing strength of the key.

Drive Shaft Design

Drive shaft serves to transfer torque from reduction gear to conveyor belt. Drive shaft drum cast d = 355 mm and width B = 500 mm.

The diameter of the shaft section near the coupling is the same as that of the slow-moving shaft of the reduction gear d = 50 mm. The moment from the drive shaft to the drum is transmitted by a key connection, the calculation of which is given above.

Selection of gears, bearings

The CMEA standard recommends the use of mainly fits in the hole system and in gears in the shaft system. The use of a hole system is preferable because it reduces the range of expensive tools (calibers) for the hole. The shaft system is used in case of technological expediency of using smooth shafts coupled with parts having different deviation limits.

As per recommendations we will accept the following bearing fits:

for external rings H7/l6

for inner rings L5/k6

To install the key in the shaft slot, use the recommended PT CMEA 5773 adapter fit P9/h9, and to install the keys and attach sprockets, use the fits with clearance H9/h9, Js9/h9, respectively.

Lubrication of gears and bearings

Lubricants in machines are used to reduce wear intensity, reduce friction forces, remove heat from friction surfaces, and also to protect parts from corrosion. The reduction of friction forces due to lubrication provides an increase in the efficiency of the machine, in addition, dynamic loads are reduced, smoothness and accuracy of the machine are increased. We accept the most common liquid industrial oil I-G-A-68

GOST 170790.

Depth of gear wheels immersion in oil must be not less than 10 mm from teeth tops.

Gearbox assembly

The radial assembly of the selected gear box design is applicable. Reduction gear case consists of 3 parts. Body parts are fixed one relative to another by control pins. This design is characterized by the complexity of machining. Mounting hole for shafts bearings is machined in assembly at body halves connected along pre-machined joint surfaces, or separately in both halves, with subsequent finishing of joint surface.