Bucket Elevator Design - Drawings

Contents

Content of the project.

1. Job for Course Project

2. Bucket elevators: basic information

3. Select Elevator Type

4. Select Buckets

5. Elevator Performance

6. Determination of electric motor power

7. Definition of traction element of elevator

8. Determination of stars

9. Calculation of kinematic diagram

10. Calculation of intermediate shaft

11. Fitting of couplings and bearings

12. Determination of electric power consumption

13. Description of rules of bucket elevator operation and repair

14. Characteristics of bucket elevator

15. List of literature used

2. Bucket elevators: basic information

Application areas. Bucket elevators are used to transport bulk cargoes - pulverized, granular and small-scale (for example, cement, sand, coal, peat, chemicals, grain, etc.) at enterprises of the machine-building, chemical, metallurgical, food industry, in the production of construction materials, in granaries.

Classification. Bucket elevators are divided into stationary and mobile (the latter are installed on loading machines), transport and technological.

Elevators have flexible traction elements (chains, belts, rope), enveloping drive and tension elements (sprockets, drums, blocks). Load-carrying elements are attached to flexible traction elements: ladles, shelves, cradles. Elevators also include drive, tensioning, loading and unloading devices, as well as casing covering moving parts. The drives are equipped with locking devices to eliminate the danger of reverse movement of the traction element under the influence of gravity of the lifted load when the engine is switched off.

By the type of traction element, tape and chain bucket elevators are distinguished. The latter are divided into single- and double-chain chains according to the number of chains to which the buckets are attached. By location in space, elevators are vertical and inclined (inclination angle 60... 82 ° to the horizon). Inclined elevators can be with idle branch freely hanging or moving along guide roller supports. Working branch of belt inclined elevators rests on stationary rollers, and working branch of chain inclined elevators can rest on both stationary rollers and guide tires in the presence of running rollers in the chain .

According to the speed of the buckets, low-speed and fast elevators are distinguished.

According to the location of the buckets, elevators with placed and closed buckets are distinguished. Elevators with closed buckets are designed mainly for lifting large-piece and abrasive weights, as well as for weights whose properties deteriorate during crumbling (for example, coke).

Elevators with placed buckets are used to transport finely fractional loads. They have a belt or chain (single-chain and double-chain) as a traction element. Loading of buckets of these elevators is carried out by exhausting the cargo that wakes up in a significant amount in the shoe due to the presence of gaps between the buckets. Elevators with placed buckets are often made fast. Buckets of such elevators are unloaded mainly under the influence of centrifugal force arising when buckets bypass the upper drum (sprocket).

Basic parameters. The main parameters of elevators are Q performance for bulk loads or Z for piece loads; height of elevator H measured between centers of upper and lower sprockets (drums, blocks); speed V of flexible traction element; power P (kW) of the drive engine.

Advantages and disadvantages. The advantages of elevators are the safety of the transported load, simplicity of design, reliability during operation, the possibility of creating a tight and soundproofing casing that protects the environment from dust and noise, small overall dimensions in the transverse direction, the possibility of supplying the load to a significant height (60... 90 m or more up to 200 m), a large range of productivity (5... 500 m3/h and up to 1000 t/h). Disadvantages include bucket breaks during overloads and the need for uniform cargo supply.

Device. Bucket elevators are designed for lifting bulk loads, having a traction element (tape or chains), to which buckets are attached. The belt is driven by a drum (and the chain by a sprocket) connected by a clutch with a drive.

The required pressing of the belt against the drum is created by the gravity of the moving parts of the elevator and the transported load, as well as by the force of the tensioner. Bulk cargo through the loading branch pipe is filled into the ladle or supplied to the lower part (shoe) of the elevator and exhausted by the buckets, rises up and is discharged through the unloading branch pipe located in the head part. Elevator casing has panels for inspection and repair of working elements.

The location of the charging nozzle at the bottom of the casing may be high and low. The high nozzle has a bottom at an angle of 60 ° to the horizontal and is designed to load wet poorly loose loads. At the low nozzle, the bottom is located at an angle of 45 °, and dry well-loose loads are supplied through it.

Discharge branch pipes are attached to upper part of casing (head) of elevators and are equipped with side hatches for inspection and cleaning. Lower edges of discharge branch pipe are edged with angles forming flange to which gravity pipes of receiving devices are fixed.

In case of a break in the electric current supply, the loaded web with elevator buckets that do not have safety devices can move down under the influence of gravity of the load, which in heavy elevators leads to an accident. To prevent this, brakes and locking devices are used. Closed block brakes are made electromagnetic or with hydraulic pushers and installed on input shaft of reduction gear box, and stops - directly on shaft of drive drum (sprocket). Centrifugal and roller stops are used.

Safety devices also include flooding annunciators of loading branch pipe with transported load. To protect the elevator elements from breakdowns in the event of stalling of the traction element (blockage of the receiving part by weight or ingress of foreign objects such as scrap into the buckets, etc.), shear fingers embedded in the drive elements are used.

Filling and unloading methods. There are two ways to fill buckets: by exhaustion and embankment. The process of exhaustion proceeds when the buckets bypass the lower drum of the elevator and creates an additional load on the buckets and the traction element .

According to the method of unloading buckets, elevators with centrifugal, gravity free and gravity directed unloading are distinguished. Centrifugal unloading is used in high-speed elevators. When buckets bypass the upper drum (sprockets), the bulk load is ejected from the buckets under the influence of centrifugal force.

Centrifugal unloading can be at both inclined and vertical elevators. Gravity free unloading is used only in elevators, the idle branch of which is inclined (in inclined elevators, combined vertically inclined or double-chain elevators with deflecting sprockets). Gravity directional unloading is performed by means of tray formed by end wall with sides ahead of overturned ladle located closely. This unloading is used in slow-moving elevators, which can be both vertical and inclined.

Slow-moving elevators with placed buckets can only have gravity free unloading, and therefore must be inclined, at least in the upper part. When using double-chain elevators in the unloading area, it is necessary to install deflecting sprockets.

Elevators with closed buckets are made only slow-moving; they have gravity directional unloading, can be vertical and inclined. Buckets are loaded with bulk. As the traction members of these elevators, one or two chains are usually used, but a belt can also be used.

Traction elements. As traction element of belt elevators there used is fabric rubberized much-gasket tape, less often wire-mesh tape. In chain elevators, plate-shaped (with a pitch of 100... 630 mm) and round-link welded chains made of steel with a diameter of 16... 28 mm with heat treatment. Bushing and bushing-roller chains are used in vertical elevators, and bushing-roller chains are used in inclined elevators. Round-link welded chains, as well as special plate chains with increased gaps (0.4... 0.6 mm) between the pin and bushing is changed during transportation of loads containing abrasive dust or causing corrosion of chain parts.

Buckets. Buckets with cylindrical bottom, acute-angle or semi-circular bottom with sides on the end wall and louvers are used in elevators.

Buckets with a cylindrical bottom are deep and small. Deep buckets are used to lift dry well-loose cargoes (sand, grains, etc.), and small ones for wet bad ones; bulk and tracked cargo. Sharp-angle and with a semicircular bottom with bucket sides are designed for heavy lump abrasive weights. Buckets are fastened to traction members with bolts and nuts. Note here that they are connected with tape by special bolts with flat head. Ladles are made of sheet metal up to 6 mm thick or cast from ductile cast iron.

Drive. Bucket elevator drive consists of electric motor, reduction gear box and couplings. The electric motor shaft is connected to the input shaft of the reduction gear by an elastic clutch, and the output shaft of the reduction gear is connected to the drive shaft of the elevator by a toothed clutch.

Drive drums and sprockets of bucket elevators are located in upper section of casing (head). In exceptional cases where the elevator actuator cannot be placed at the top, it is permissible to place the drive drums at the bottom of the casing, but it should be borne in mind that this increases the tension of the flexible member and the loss in the bearings.

Diameter of drive drum is taken depending on speed of movement and method of ladle unloading.

Tensioners. Bucket elevators use screw and spring-screw tensioners. Tensioner stroke 200... 500 mm. Tension drums of belt elevators are made with grid rim to prevent particles of bulk load from sticking to rim. In belt bucket elevators, a lever-truck tensioner is also used that automatically maintains constant belt tension, which is important when there is a friction drive.

In two chain elevators, one of the sprockets is fixed on the tension axis by a key, and the second one can freely rotate around the axis to self-install and compensate for inaccuracies in the manufacture and assembly of the set of drive shaft and chains.

Guide tires. Guide tires are attached to casing of inclined and vertical elevators. In inclined elevators, they are located along the entire height and serve as a support for chain rollers. At the ends of the tyre there are receiving roundings providing smooth entry of plate-chain rollers on them. In vertical elevators, guide tires are made in the form of short sections and serve to limit transverse swinging of belts or chains with buckets.

Description of rules of bucket elevator operation and repair

Grease the bucket elevator and check the rolling bearings according to the technical maintenance sheet. Check the condition of the traction element - the chain, prevent its rupture, constantly check the tension of the tensioning drum, check the oil level in the reduction gear box, the state of the electric motor contacts, the reliability of the coupling.