Belt conveyor device and operating principle. Belt Conveyors

External transport (rail, road, water, air) delivers raw materials, fuel and auxiliary materials to enterprises, and also exports finished products. In-plant transport (cranes, loaders, conveyors, etc.) moves raw materials, semi-finished products and parts within workshops, between workshops and transports finished products to the warehouse, and carries out loading and unloading operations. In addition, conveyors, as industrial transport, are widely used directly in the technological process of manufacturing or assembling manufactured products.

Continuous transport machines move cargo in a continuous stream, in most cases along the same specific route. The cargo flow can be in the form of a continuous stream of bulk or lump materials, or in the form of separate portions of these materials, as well as piece cargo. Continuous transport machines are used when moving identical loads.

They are characterized by the same type of transport operations, so they are much easier to automate than lifting operations.

Continuous machines with a traction element are varied in type and design. What they have in common is the presence of a traction element, which can simultaneously be a working element (for example, belt conveyors) or carry working elements (elevators, etc.). All continuous machines with a traction element, despite their design features, have components whose working process theory is general. The general issues of this theory include determining the coefficient of resistance to movement and engine power, calculating the drive and tensioning devices, etc.

According to the degree of mobility, transporting machines are divided into:

· stationary;

· mobile.

Conveyors are most widespread in all industries.

For example, belt conveyors are designed for transporting bulk (powdery, small- and medium-sized materials), as well as small piece goods in a horizontal or close to it direction.

In chain conveyors, the load rests on plates (plate conveyors) or in buckets (bucket conveyors). Plate conveyors are designed for transporting large pieces, abrasive and heated materials, as well as large piece goods in a horizontal or slightly inclined direction. Bucket conveyors are designed for transporting bulk cargo in buckets in horizontal, inclined or vertical directions.

Elevators are used to move loads in buckets in a vertical or steeply inclined direction.

As a rule, continuous transport devices operate without idling, due to which their utilization rate is always higher than the utilization rate of periodic lifting machines (for example, cranes), which after each working stroke must return for a new empty load.

The extremely wide variety of types of cargo and the conditions for their movement has created a correspondingly large number of types of transport devices.

During the construction and repair of residential and industrial buildings, there is a need to move bulk, lumpy or small-piece materials and garbage over short distances horizontally or at an angle. Often transport must be carried out continuously. To perform such work, belt conveyors are most often used. The industry produces mobile belt conveyors with a length of 5, 10, 15 m and a belt width of 0.4 - 0.5 m. The unloading height of mobile conveyors can vary from 1.5 to 3.3 m, the belt movement speed is 1.5 - 2.5 m/s, and for a 15-meter conveyor up to 15 m long - from 2.2 to 5.5 m. Belt speed - 1.6 m/s. The dead weight of these conveyors is 0.4 - 1.2 tons.

Belt Conveyor

A belt conveyor is a widespread type of continuous conveying machine with a traction element. The length of belt conveyors depends on the strength of the conveyor belt. They usually have a length of 25...100 m with one drive drum and a conveyor belt with textile cord. The productivity of belt conveyors depends on the width of the conveyor belt, the speed of its movement, the characteristics of the transported cargo and can lie within a very wide range (from several tens to tens of thousands of t/h).

Serially produced belt conveyors have a conveyor belt width of up to 2 m at a movement speed of 1...5 m/sec. The main parameters of serial belt conveyors are the width of the conveyor belt, its speed and the diameter of the drive drum. Conveyor belts most often use rubber-coated cotton, synthetic or blended fabric conveyor belts, commonly referred to as rubber-fabric conveyor belts. Hemp and cotton conveyor belts are installed much less frequently. The basis of rubber-fabric conveyor belts is made up of several layers of cotton, synthetic or mixed fabric impregnated with rubber, coated on the outside with a thick layer of rubber. Layers of fabric give the conveyor belt strength and resistance to longitudinal stretching, and rubber is a material that binds and protects the main fabric from mechanical damage and dampness.

The belt conveyor (see Figure 29) is made in the form of a frame with two metal wheels, on which an endless rubber-fabric belt resting on support rollers is mounted between two drums. One drum is driven, has screw devices for its movement along the frame, which allows you to adjust the belt tension. The second drum is the driving one, connected through a gearbox to an electric motor. The conveyor frame has a device for changing its installation angle and unloading height. The conveyor belt in most cases consists of 5 - 7 layers of rubberized cotton fabric. Tapes made of synthetic materials are increasingly being used; they are much stronger.

In recent years, tapes with a corrugated surface have also been used. The angle of inclination of the conveyor frame in this case can reach 35°. In exceptional cases, corners (brackets) are attached across the belt, which ensures transportation of material at angles of up to 50°.

Traction force R(H) on the drive drum is determined from the expression:

, (41)

Where N- conveyor motor power, kW;

v T- belt speed, m/s;

Transmission efficiency.

Figure 29 shows a mobile belt conveyor: a) - general view; b) - kinematic diagram; c) - arrangement of the belt on rollers: 1 - tension drum; 2 - receiving funnel; 3 - tilt mechanism; 4 - cargo tape; 5 - roller supports; 6 - frame; 7 - drum motor; 8 - cleaning device; 9 - supporting roller support; 10 - running wheels; 11-rope pulley block; 12 - control panel.

Conveyor productivity (kg/s) when moving bulk materials is determined from the expression:

, (42)

Where A- cross-sectional area of ​​the material transported by the belt, m2;

R- density of the material, kg/m3.

Conveyor productivity (kg/s) when moving piece goods is equal to:

, (43)

Where l- average distance between load centers, m;

G- mass of one load, kg.

The number of spacers (layers) of tape (pcs.) is determined from the expression:

, (44)

Where T- force at the advancing end of the tape, N;

K r- strength of fabric of one layer, K r= 130 - 300 N/cm;

Coefficient equal to 2.72;

Wrapping angle of the drive drum belt = 180 - 250°;

Friction coefficient = 0.1 - 0.25.

Depending on the operating conditions of the conveyor (belt tension), conveyor belts with the number of layers of fabric (linings) from two to ten are used. The thickness of each gasket (fabric impregnated with rubber), depending on the type of fabric, is 1.1...1.7 mm, the thickness of the outer rubber lining is from 0.75 to 8 mm. Breaking load on conveyor belts ( F times) ranges from 65kg to 400kg per 1 linear cm. the width of each layer of the conveyor belt, and the permissible operating tension is from breaking load.

So, for example, for a 400mm wide conveyor belt made of BKNL-65-2 cotton fabric with three spacers, the breaking load is

, (45)

65*40*3=7800kg, and the permissible operating tension of the tape at the permissible tension of 1 linear cm. width 65/12=5.42 will be:

, (46)

In this case, the operating voltage of the tape will be: T=5.42*40*3=650.4 kg.

Recently, steel conveyor belts have become widespread. They are made by cold rolling, 0.6-1.4 mm thick, up to 650 mm wide.

Operation of a belt conveyor. The conveyor belt is driven (just like a drive belt) by friction against the surface of the drum. The force that can be transmitted by the drum to the conveyor belt depends on the angle of the drum wrapping the belt and the power of the electric motor driving the drum; if the first is insufficient, the drum begins to slide along the conveyor belt; if the second is insufficient, it does not pull it.

To avoid slipping when transmitting large forces on long, heavily loaded conveyors to increase the coefficient of friction f the surface of the drum is covered with leather or rubber, and also covered with wooden planks.

To increase the wrap angle, a guide drum or a so-called “tandem drive” is most often installed, i.e. a conveyor belt that goes around two drums receiving movement from one drive. It should be noted that with the latter method, the conveyor belt wears out greatly due to unequal tension on both drums and three times bending on both sides.

The most rational way to increase the adhesion force between the conveyor belt and the drum is to use an additional pressure belt, which presses the working belt against the drum and thereby increases the friction of the conveyor belt.

The transmission of motion from the electric motor to the drum is belt-based, depending on the gear ratio with one or two pairs of gears, or through a gearbox.

Bucket elevators

Bucket elevators are used for continuous vertical lifting of bulk cargo. The elevator contains a flexible traction working element in the form of one or two chains stretched over a sprocket, to which working buckets are attached. The elevator drive is connected to the upper sprocket and has a ratcheting device that enables reverse movement of the belt. At the bottom of the belt there is a tension drum or sprocket and a screw tensioning device mounted on the casing.

Figure 30 shows a diagram of a bucket elevator: 1 - traction chain; 2 - ladle; 3 - drive sprocket (drum); 4

casing; 5 - tension sprocket (drum).

, (47)

Where k- bucket filling coefficient ( = 0.6 - 0.8);

q- bucket capacity, m 3;

P- number of buckets on the chain;

v T - bucket speed, m/s;

The load-bearing and traction element of a general-purpose belt conveyor (Fig. 2.2) is an endless flexible belt 9, resting with the upper (working) and lower (idle) branches on roller supports 6, 17 and envelope at the ends of the drive conveyor 10 and tension 2 drums. On short conveyors, often used to move piece goods, the working belt run can slide on a wooden or metal deck. The movement is transmitted to the belt by friction from the drive drum. The required initial tension on the running branch of the belt is created by the tension drum using tension device 1 cargo or screw type. Bulk cargo is fed onto the belt through a loading funnel 3, usually installed at the beginning of the conveyor at the end drum 2. The belt unloading can be end or intermediate, for which a mobile unloading cart 7 or stationary plow dumpers are used. The direction of the flow of cargo discharged from the drum is ensured by the unloading box 8, having one or two funnels.

To clean the working side of the belt from remaining particles, install rotating brushes 11 (nylon, rubber) or a stationary scraper. For many types of cargo, the installation of a cleaning device is absolutely necessary, since adhered particles form a hard-to-remove uneven crust on the rollers and can lead to their uneven rotation, causing accelerated wear of the belt. A rotating drum with rubber spiral scrapers cleans the belt well.

To remove particles that accidentally fall onto the inner surface of the lower belt branch, it is recommended to install an additional dump scraper in front of the tension drum 16. Cleaning the belt after the drive drum is also necessary because stuck particles, falling off from shaking on each support of the lower branch, can form blockages of small particles, complicating the operation of the conveyor.

To center the travel of both branches of the belt and prevent its excessive lateral displacement, various centering roller supports are used 5.

The belt conveyor drive consists of a drum, an electric motor 14 , gearbox 13 and couplings 12. On the turning sections of the route branches, roller batteries are installed, creating a smooth bend of the belt, or deflecting drums 4.

All conveyor elements are mounted on metal structures 15, attached to the foundation or supporting parts of the building. A metal structure with a drive and an unloading box is called a drive station. Part of the structure with a tensioning device and a loading funnel makes up the tensioning station. Between both stations there is the middle part of the conveyor, which is made of identical linear sections. Linear sections, transition sections, drive and tension stations are connected by bolts. As a rule, multi-roller supports that form a grooved belt are used for bulk cargo. This belt shape, with the same width and speed, allows for more than a twofold increase in productivity while eliminating cargo spillage.

Two-drum dump carts are designed for intermediate unloading of only bulk cargo to the sides of the belt through one of the outlet pipes. Stationary plow dumpers can be used for both bulk and piece goods. There are known designs of plow dumpers on mobile carts.

In addition to the above elements, conveyors are equipped with locking devices or two-shoe normally closed brakes, as well as belt catchers located on inclined sections of the route in case of breakage, safety devices and automatic control devices.

The design features of the conveyor depend on the type of belts used. Conveyors with a steel belt, with the same design as general-purpose conveyors, differ from the latter in individual elements due to the increased rigidity of the belt. Drums for steel belts have a larger diameter, and roller supports (Fig. 2.3, A) made in the form of disks 1 on one axis, spring rollers 4, flooring 2 with sides 3 or without sides. For conveyors with wire belts (Fig. 2.3, b) supports with one horizontal roller can be used. On these conveyors, due to the looseness of the belt, mainly piece goods are transported.

Conveyors with wire belts can operate at temperatures up to 1100 ºС, and with steel belts (heat-resistant) - up to 850 °С.

In rope belt conveyors, the belt 5 (Fig. 2.3, V) performs the function of only a load-bearing element. It is located on two traction ropes 6, resting on supporting blocks 7 located along the entire conveyor route.

Ribbon combination 8 with traction chain 9 made it possible to create belt-chain conveyors (Fig. 2.3, G). The traction chain is supported by guide blocks 11, and the side parts of the belt rest on inclined support rollers 10.

To reduce the length of an inclined conveyor and, accordingly, reduce its cost and the production space it occupies, it is recommended to use steeply inclined and vertical conveyors. These conveyors can be with upper clamping elements (Fig. 2.4, a): with a chain mesh belt /, rubber-fabric belt 2 and skating rinks 3, with additional paddle belt 4. For highly dusty materials, conveyors with a tubular belt are used 6 (Fig. 2.4, b), having a zipper fastener 5 and device 7 to open and close it. In rough terrain it is convenient to use conveyors (Fig. 2.4, c) with a belt 11, suspended on chains to brackets 10 and steel wire rope 8, lying on support blocks 9. A variation of these conveyors are those with a tubular belt and a zipper also suspended from steel wire ropes on chains.

In Fig. 2.5, A shows a light-duty high-angle belt loader with variable inclination and crossbars 2 on the tape, and in fig. 2.5, b- mobile conveyor for loading work in construction. Most mobile belt conveyors use a drum motor 3 (Fig. 2.5, A) with a drive built into it and a screw tensioning device / located in the upper part of the machine.

If the installation conditions of conveyors require a significant reduction in their weight, for example, on spreader bridges, then belts without supporting roller supports are used, weight

which can reach 35% of the conveyor weight. In this case, an air cushion (Fig. 2.6) or permanent magnets (Fig. 2.7) are used to suspend the tape. The upper and lower branches of tape 1 in the first case are supported by thin (0.4 ... 1.0 mm) layers 2 and 3 air with a slight excess pressure (2 10 3 Pa), the creation of which requires 0.3 ... 0.8 kW of energy for every 1 m of conveyor length. The spread of conveyors with air-suspended belts is hampered by the need to use energy-intensive blowing equipment, the difficulty of maintaining a gap between the belt and the chute, and dust accumulation of transported goods.

Replacing rollers with permanent ferrite-barium magnets 2 (see Fig. 2.7) in the form of plates (120 X 80 X 15 mm) is possible in combination with a special tape /, in the rubber lining of which barium ferrite powder is vulcanized, giving the tape permanent magnetic properties.

When the tape is combined with supporting elements of the same poles, the tape is held in suspension by a lifting repulsive magnetic force reaching 3 kN per 1 m 2 of tape. Although they are completely silent and have low energy consumption, magnetic suspension conveyors have significant disadvantages. They require the use of special tapes; it is difficult to ensure their lateral stability. These conveyors cannot transport materials that have magnetic properties.

Underground conveyors occupy a special place. They are designed for use in confined spaces, as well as for moving people and heavy piece goods, which requires, first of all, compliance with safe operation standards.

Belt conveyors of high power and considerable length are similar in design to general purpose conveyors. However, their individual elements differ not only in their proportional increase in size, but also in their qualitative specific features. For example, the drive can be made with two drive drums; the tensioning device has a system for regulating the belt tension during startup and when its load changes. High-capacity conveyors must be calculated using refined methods. In this case, it is especially important to use reasonably accurate values ​​of the coefficients of resistance to the movement of the belt and concentrated resistances at loading and intermediate unloading points.

To load the conveyor, feeders are used with a forced and strictly defined supply of cargo corresponding to the calculated capacity of the conveyor. For safety reasons, conveyors use devices to monitor the operation of mechanisms and switches that allow the conveyor to be stopped at any point along its route.

Today it is difficult to imagine high-performance production without the use of a conveyor. To move cargo, including bulk cargo, closed belts are used. We can say that this is a continuous unit that has a load-carrying body (flexible belt). Let's take a closer look at what a belt conveyor is, what its purpose is, its scope of application, and also what the intricacies of operating this equipment are.

Scope and purpose

Today, this is one of the most promising types of transport, which is practically indispensable for large cargo flows. In addition, it is a mandatory part of any heavy and light production. It is used in metallurgy, for transportation in the food industry, medicine and so on. The operating principle and device are practically the same in all cases. Differences may lie in the type of belt, its load capacity and flexibility, as well as drive power. In most cases, this type of conveyor makes it possible to partially automate production and reduce the amount of manual labor. Taking this into account, the transported vehicles in question are subject to strict requirements. Much of this relates to the strength, performance and interchangeability of the worn belt. The units are capable of operating in a temperature range from -50 to +45, which is determined by the technical characteristics of the supporting body.

Operation and design of a belt conveyor

The belt is the working part of the conveyor, it is pre-tensioned and connected. between the belt and the drive drum it is driven. Moreover, the determining factor is the friction force due to which the load-carrying and traction body moves. To avoid deflection of the belt along the length of the conveyor, roller supports are installed, on which it rests during movement. As you can see, the device of the unit is quite simple. An interesting point is the speed of replacing worn out tape. This is done as follows: during the operation of the conveyor, at the junction point, the load-carrying organ is steamed and a new tape is attached to it, by riveting or vulcanization. After the drive drum has completed a full cycle, the other end is secured. This approach is good because there is practically no equipment downtime during operation, since installation is carried out in a few minutes, although much depends on the type of traction element. Brushes are installed to clean the belt, and centering rollers are used to avoid skewing. The design of the belt conveyor is such that the unit can be used in many industries. Now let's move on.

Benefits of using a belt conveyor

Let's look at the main advantages that this unit has. The main advantage of a belt conveyor is that it can be used to transport goods over a very long distance. In some cases, the length of the load-carrying organ can reach 3-5 kilometers. No other pipeline can be this long. This is due to the heavy weight, complex design and, most importantly, the high cost of the equipment. In the case of a belt conveyor there are no problems. Another undeniable advantage is high performance. Sometimes the speed can reach 6-10 m/s, with a belt width of 2.4-3.0 meters. In this case, productivity can exceed 20-30 thousand tons per hour. In addition, the belt conveyor is a universal transport line. This is due to the fact that a wide variety of loads can be moved. Another important advantage is the ability to move loads in an inclined position. As the angle and duration of the conveyor increases, its speed decreases.

Disadvantages of belt conveyors

It is worth saying that there are also significant drawbacks that limit the scope of application of transport devices of this type. The main disadvantage is the high price of the tape and rollers. In most cases, the traction and load-carrying body costs approximately 30% of the total cost of the installation, which is not a small amount. Although here a lot depends on the purpose, as well as technical characteristics (material, number of layers, etc.). Another disadvantage is that the conveyor belt drum moves the belt using friction. This limits the lift angle so it cannot exceed 20 degrees. In addition, it is quite problematic to move dusty loads, which during movement can partially evaporate and crumble. It is difficult to work at temperatures that are too low, as well as at temperatures that are too high. Thermal exposure will change the characteristics of the flexible tape and also lead to destruction.

Operation of Belt Conveyors

As noted above, the LC can operate at high speeds. This makes the belt conveyor more productive compared to other conveying units. The main feature of operation is that it is possible to create complex routes. For example, you can make a complex route with bends, horizontal and inclined sections. Even under difficult operating conditions (temperature changes, high dust levels, etc.), the belt conveyor ensures reliable operation without failures. In most cases, with proper maintenance, you can clearly predict the period of failure of the traction element. This allows you to operate the device without downtime. To date, a huge number of drives have been developed that ensure the operation of the LC. As the length increases, several motors are installed to ensure normal operation. When one drive exits, the second one will work. In this case, although productivity will decrease, there will be no downtime.

Device and design of the tension and drive station

The drive of a belt conveyor consists of a motor, a gearbox and several roller or deflection batteries are installed at bending points, creating a smooth transition. The entire structure, together with the drive, is mounted on a foundation that must be laid first. The drive station consists of a drive, as well as a loading box, and the part where the tensioning device and loading funnel are located is called the tensioning station. Between these two stations there is the middle part of the conveyor; it is made of several linear sections. The latter consist of identical linear sections connected to each other by bolts. Now let's talk about what types of conveyor belts there are and what their fundamental differences are. There are several interesting points here.

Classification of belt conveyors

There are some signs according to which these devices can be divided into several groups:

• by area of ​​application: there are general purpose, special and underground (transportation of people, rolling, and also mobile);
• according to the shape of the route: simple (with a straight section), complex (with an inclined broken route), as well as curvilinear or spatial (bending in the plane of the load-carrying body);
• in the direction of movement of the load: lifting and lowering;
• according to the shape of the belt and the placement of the load: there are flat and grooved belts in various modifications;
• by the angle of inclination of the route: horizontal, inclined, steeply inclined (angle more than 22 degrees) and vertical.

It is worth understanding that, in addition to this, the belt conveyor scheme involves the use of various traction and load-carrying organs. Tapes can be rubber-fabric, rubber-rope, wire, or steel. The type of tape is selected based on the conditions under which it will work. For example, steel traction elements are used to work at high temperatures (up to 850 degrees), just like wire ones, which can transport loads at an operating temperature of 1100 degrees Celsius.

Mine conveyors

Separately, a few words need to be said about transport devices operating underground. It is noteworthy that this type of scheme is somewhat different. The degree of reliability increases several times. This is due to the fact that the load-carrying body is used to transport people, as well as heavy piece goods, and all this is done in cramped conditions. The drive, for example, has two tension drums, which makes the device not only more powerful, but also ensures sufficient reliability.

Conclusion

Today, the popularity of belt conveyors is constantly growing. For this simple reason, new types of load-bearing organs are constantly being developed. In particular, it is important to create high-strength, heat-resistant parts. For example, it is necessary to increase the service life of rollers that constantly fail. We can say that the operation of a conveyor belt is considered quite cheap. If you move cargo over a distance of up to 30 km using LK, it will be much more economical than doing it by road.

What are conveyor belts? Technical characteristics, installation features.

Belt conveyors are used to move bulk, lumpy and piece goods over distances sometimes reaching 10-12 km or more. Such conveyors are usually made up of separate sections. The conveyor route in the horizontal plane is straight, but in the vertical plane it can be inclined or have a more complex configuration. The traction and load-carrying body is a belt that moves along stationary roller supports, bending around the drive, tension, and sometimes deflection drums. The load moves on the belt along with it. Depending on the type of roller supports, the belt has a flat or grooved shape.

The length of belt conveyors reaches 10-12 or even more kilometers! The width usually ranges from 300 to 2000 mm.

The flat belt conveyor is used primarily for moving piece goods. The necessary belt tension is provided by a tension station, usually a freight station, and in mobile conveyors - a screw station. The conveyor drive (drive station) consists of an electric motor, gearbox, drum and couplings. Bulk cargo is loaded onto the belt through a guide tray or funnel, and unloaded through an end drum or using a plow or drum dumper. Belt conveyors have high operational reliability and provide productivity from several t/h to several thousand t/h. The width of the fabric belts is from 300 to 2000 mm, the speed of the belts is 1.5 - 4.0 m/sec. Short mobile belt conveyors are mounted on wheels and are used for loading and unloading operations.

Belt conveyor is one of the most common types of continuous transport machines. The supporting body is an “endless” conveyor belt.

The belt is driven by a gear motor via a drive drum.

Nowadays, the conveyor belt and other transport equipment bear the main burden of delivering grain to the required elevator units. This saves money and time.

Types of Conveyor Belts

Belt conveyors are of open and closed type. Closed belt conveyors protect the cargo from moisture and sunlight if work is carried out outdoors. Isolation from external factors can significantly protect the cargo. It is also worth noting that modern belt conveyors are made from technologically advanced, reliable, durable materials and components. Depending on the load per linear meter of conveyor length and the cargo being transported, the type of belt may be different. As is its width.

Characteristics of conveyor belts

Characteristics of elevator belt conveyors

1. A galvanized, painted box is used. The length of the box section can be up to three meters. The housings of the head, tail and box are sealed. The base of the conveyor belt has bushings made of antistatic material. They are installed in grooves, taking into account possible expansion of the metal. The conveyor uses a wear-resistant belt. A sensor kit is also available. If there are additional sides, straight or trough roller supports can be installed on the conveyor belt.
2. The main engines of the working process of a belt conveyor are drives. They are installed in drums along which the belt moves. Driven and non-driven drums are the main equipment of the conveyor belt. Variations are possible. Drums with one shaft console designed to connect to the drive. Or with two consoles, symmetrically located relative to the axis of the conveyor belt, connecting, respectively, two drive mechanisms. In this case, the power of two simultaneously operating drives is equal to half the power of the drum. Drums with two consoles on a conveyor belt are designed for redundant drive mechanisms. This allows one drive to work, and the other to be a spare - on the safety net. And each mechanism is designed to transmit maximum power to the drum.
3. On convex sections of the conveyor belt, non-driven drums are used instead of lower roller bearings. They are also used in the head and tail parts of the conveyor, as deflection drums.

Conveyor belt performance

The belt conveyor consists of the following elements (Fig. 4.1): a closed (endless) flexible belt 5 ; tail tensioner 1 and front wheel drive 7 drums; working rollers 4 , which support the upper (working) branch of the belt and form its profile (straight or grooved); lower non-working rollers 10 , which support the lower (non-working) branch of the tape; roller battery 13 ; boot device 2 ; plow unloader 3 or unloading funnel 8 ; cleaning device 9 ; drive 11 including an electric motor, gearbox and couplings; tensioner 12 ; metal structures (frames) 6 . The main components of mass-produced general purpose conveyors are standardized.

Rice. 4.1. Conveyor belt diagram

The main advantages of belt conveyors are: simplicity of design, reliability of operation, ease of maintenance and repair, relatively small weight, the ability to move goods at significant angles of inclination and unload them anywhere along the conveyor route, continuity of transportation with a high degree of automation.

The disadvantages of belt conveyors include the relatively high cost and low durability of the belt, the inability to operate at high temperatures, the difficulty of transporting goods with sharp edges, etc.

The productivity of belt conveyors depends on the width, profile and speed of the belt and the bulk density of the transported cargo and can reach 30,000 tons / h.

Metallurgical enterprises usually use standard tapes with a width of 300...3000 mm. The belt speed is usually 1...3 m / s or more (up to 8 m / With). The length of belt conveyors is determined by the strength of the belt and the characteristics of the drive. With one drive drum and when using a belt with a textile base, the conveyor length is usually 25...100 m; the use of multi-drum drives and modern high-strength belts makes it possible to increase the conveyor length to 8...10 km. The routes of belt conveyors are very diverse and can be horizontal (Fig. 4.2, A), inclined (Fig. 4.2, b), combined (Fig. 4.2, V, G, d, e) etc. In this case, to prevent the load from shedding, the lifting angle β is taken equal to no more than 2 / 3 angles of repose of the transported cargo in motion φ D; typically the β value is 20°.

Conveyors are divided into stationary, mobile and portable. At metallurgical enterprises, stationary conveyors are the most common. Mobile conveyors are used to supply cargo to several points, usually located along a certain line (bunker compartments, loading funnels of technological equipment, etc.). Portable conveyors are usually used for various auxiliary and repair work.

According to their design and purpose, there are general purpose conveyors (from GOST 22644-77 to GOST 22647-77) and special ones - for the food industry, instrument making, etc.



Rice. 4.2. Conveyor belt routes:
A – e, l– with single-drum drive; and – To– with double-drum drive; P – drive; NU – tension device;
r issue and r vog – radii of conveyor curvature on the convex and concave sections, respectively