Course Project on Machine Parts ( Belt Conveyor Drive )

Contents

Tape Conveyor Brief

Description of the sequence of assembly and disassembly of individual devices, assembly and adjustment of worm engagement, adjustment of rolling bearings, as well as selection of bearing fits

Adjustment of worm gears

Adjustment of rolling bearings

Adjustment of high-speed shaft rolling bearings

2.2.2. Adjustment of low-speed shaft rolling bearings

Select Bearing Fits

Installation and removal of bearings

Calculations

Kinematic and energy calculations

3.1.1. Electric motor selection

3.1.2. Determination of drive ratio

3.1.3. Determination of torque on drive shafts

Analysis of calculation results on computers

Worm Gear Box Sketch Layout

3.3.1. Mechanical Transmission Design Sequence

3.3.2. Sketch Layout Sequence

Bearing Life Calculations

3.4.1. Durability calculations of high-speed shaft bearings

3.4.2. Low-speed shaft bearing durability calculations

Shaft check calculations

3.5.1. Shaft static strength calculations

3.5.1.1. Calculation of high-speed shaft for static strength

3.5.1.2. Calculation of low-speed shaft for static strength

3.5.2 Calculation of shafts for endurance

3.5.2.1. Calculation of low-speed shaft for endurance

Calculation of key connections

3.6.1. Motor shaft connection - pulley

3.6.2. High speed shaft connection - pulley

3.6.3. Slow shaft connection - chain coupling

Shell Part Design

Selection of oil grade and engagement lubrication system and bearings

Calculation of the welded connection of the bracket with the frame

Select Interference Fit

List of used literature

Applications

1. Tape Conveyor Brief

Belt conveyor - a continuous transport machine for horizontal movement of various loads, installed in a heated room. It can also move loose and loose materials. The conveyor is widely used for mechanizing loading and unloading operations, for transporting products in process flow lines, etc.

At present, a large number of different conveying devices are known, differing in both operation and construction.

Drive consists of electric motor, worm reduction gear, frame, chain coupling. The drive uses an asynchronous motor. A reduction gear is a mechanism consisting of gear or worm gears made in the form of a separate unit and serving to transfer power from the engine to the working machine.

The purpose of the reduction gear is to reduce the angular speed and increase the torque of the driven shaft compared to the driving shaft.

2. Description of the sequence of assembly and disassembly of individual devices, assembly and adjustment of worm engagement, adjustment of rolling bearings, and selection of bearing ring fits.

2.1. Adjustment of worm gears.

There are several methods of adjusting the engagement of the worm engagement, the purpose of which is to align the middle plane of the worm wheel with the axis of rotation of the worm in order to obtain the proper area and location of the contact spot.

First of all, it is necessary to adjust the axial clearance or "axial play" of the rolling bearings, since otherwise it is not possible to get the correct engagement.

Adjustable radial thrust bearings are considered to be properly adjusted if the axial clearance is within the required range when the shaft is moved axially from one extreme position to another. Clearance value is determined by reference books depending on bearing diameter, distance between supports and temperature mode of operation.

To adjust the engagement in individual and small-scale production, a thin layer of paint (Berlin azure according to TU 610128273) is applied to the worm turns, then the worm is rotated so that the worm wheel makes at least one turn and visually controls the size and location of the contact spot on the teeth of the wheel. The spot should be located in the middle of the tooth optimally with a slight displacement towards the exit of the worm turns from engagement. By shifting the wheel in axial direction "by a spot" with the help of a set of metal gaskets or with the help of threaded parts, the necessary location of the spot on the teeth of the wheel is achieved. The performance of this operation largely depends on the performance of the transmission: efficiency, resource, transmitted moment, etc. This method is rather laborious and inaccurate (essentially it is a selective assembly, and the dimensions of the spot largely depend on the thickness of the applied paint layer). The best results are to control the stain if the paint is applied to two nearby teeth of the wheel and turn it for 10... 15 revolutions. In laboratory conditions, spot control is applied after oxidizing the surface of the wheel teeth with special solutions and turning the transmission under a small load (... 10 20% nominal). In this case, the spot is visible quite clearly, but the solutions are toxic and it takes 15... 20 minutes to oxidize. Spot control on the "glare" after the run-in is also applied .

In large-scale production conditions, special assembly slipways with automatic control operations are used. In the latter case, greater accuracy is required in the manufacture of the basing surfaces of the transmission parts.

2.2. Adjustment of rolling bearings.

2.2.1. Adjustment of high-speed shaft rolling bearings.

Bearings in LH support are installed in sleeve. For attachment of bearings on shafts splined nut is used, which from spontaneous unscrewing is locked by multi-flange washer.

Mounting in the housing: bearings in the left support on one side from above are pressed by a compensating ring, which in turn is compressed by a cover, and from below after a multi-flange washer we install an additional ring that improves the contact of the bearing with the washer. Bearing in RH support rests against shaft ledge, and on the other side it is attached by spring thrust flat ring.

Adjustment of bearings: made by a set of gaskets installed under the flange of the bearing cover. For this purpose, a set of thin metal gaskets is used.

2.2.1. Adjustment of low-speed shaft rolling bearings.

Bearings are fixed on one side due to projection in worm wheel hub, and on the other side by bearing cover. Adjustment is carried out in the same way - with the help of a set of metal gaskets.

2.3. Select bearing fits.

Inner and outer diameters of rolling bearings are manufactured with relatively small deviations from nominal dimensions. The required fit of the rings is ensured by the selection of appropriate deviations in the dimensions of the mating parts. Fits are assigned depending on bearing operation mode and type of rings loading.

As per Tables 7.6 and 7.7 (see [1], page 113) we select the tolerance of external and internal rings of bearings. For all used bearings of the reduction gear - tolerance of the inner ring - k6 (ring loading is circulating, light mode, calm load with short-term overloads); the admission of an external ring - H7 (loading of rings local, the easy mode, loading quiet with short-term overloads).

2.4. Installation and removal of rolling bearings.

Improper and careless installation and removal is one of the main reasons for premature failure of bearings. During installation it is necessary to ensure alignment and absence of bearing skews relative to the mounting surface. Misalignment of the rings makes it difficult to fit and leads to the formation of bursts on the mounting surfaces, and in some cases - to the rupture of the bearing rings. Chamfers on the mounting surface contribute to the coaxial position, and central application of pressing force helps to reduce distortions. In all cases of mounting, in order to avoid dents on treadmills, it is unacceptable to transfer the press force through the rolling bodies. The press-in force is drastically reduced when the bearings are heated before assembly in the oil bath to a temperature of 100,120 ° C. At a properly mounted bearing, the inner ring must fit tightly along the entire circumference to the thrust collar.

In outer rings subjected to local loading, the fit is weakened, which greatly facilitates assembly. Presses and mounting sleeves or mandrels are used to fit bearings into the housing with interference.

Demounting of bearings mounted on shaft or housing with interference is carried out on press or with the help of screw extractors.

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