Great Changes in Technology of Conveyor Belt

Great Changes in Technology of Conveyor Belt

With the development of scale of mine, belt conveyor has kept on towards large scale and presents features of large capacity and long distance. Belt conveyor with long distance and multi power has achieve successful research and development, it changes the single load-carrying way that is given by rollers and adopts multipoint electric drive. This method can address the traditional problems that are changing conveyor belts frequently and belt breakdown easily. Also, the successful development of this kind of belt conveyor can reduce the cost of equipment greatly. What’s more, its advantages are reducing thenumber of transshipment or fall of ore during operation and avoiding environmental pollution.

 

The successful development of belt conveyor with 1km-100km belt length, adopting multipoint electric drive which can reduce 10%-30% investment and operation cost. Especially, it can decrease belt strength and eliminate risk of tapebreak of upward transport belt conveyor with large angle and long distance. And then it can prolong the lifespan of belt more than 5 times. Multi-power belt conveyor not only can achieve the goal of lower investment, lower consumption and resistance, but also operate stably more than 10 years. In this way can it improve the running rate and economic benefit greatly.

The Risks of Conveyor Belt Running Deviation

The belt running deviation is rather harmful during the operation. According to the actual operation of belt conveyor, the deviation effects on the operation and production of belt conveyors are mainly in the following aspects:
1. Failure breakdown emergency stop device
The failure breakdown emergency stop device with protective purposes is installed on the belt conveyor. When the belt deviation occur and near the failure breakdown emergency stop device, it will causes the device to stop the machine immediately, and hence causes the conveying process to stop. This will affect the efficiency of production line, and hence increase the cost of production. Some serious cases might lead the project unable to finish on time, or even causes the undesirable contract disputes.

2. Reduce the life-span of main components
Firstly, the breakdown of roller, bearings and other mechanical components, such as belt running deviates frompulley will cause the increasing of the force of roller, and hence it will increase the probability of failure. Secondly, it leads the belt to be worn out in a shorter period. The belt running deviation cause the materials spread onto the return belt. It will cause the belt and roller encapsulate to wear and tear abnormally as the materials can’t be fully removed from the return belt. Thus, the life-span of belt and roller will be shorten. Thirdly, it leads the tear and wear from the edge of belt, if the edge of belt collides with frame for a long time during the operation, it will cause the severe wear of belt edge and thus affects the life-span of belt which will leads to the increase of maintenance cost and also the operation cost. When the serious belt deviation occurs, it causes belt tearing directly. Belt deviation might lead to serious overturning of belt, causing the increasing of unilateral force ,hence it will lead to belt transverse fracture. 

The Role of Conveyor Belt Cleaning Device

The belt conveyor is often used to transport viscous materials, such as coal dust, mud, powder materials and etc.. Some of them will stick on the working surface of belt conveyor, which cannot be removed when discharged the materials. At this time, the adhesive material will then enter the return idler, the roller become dirty as attachment stick on it. Materials enter the roller casing, thereby increasing the radial and thrust load of bearing block, causing rapid wear of bearing. The materials deposit on the roller casing will tear the rubber surface of the belt conveyor, accelerate the wear out failure of belt conveyor. If sticky materials enter the tail bend pulley, it will stick on the surface of roller. The more the viscous materials stick on it, the greater the force of the sticky materials, which will result belt deviation and increase belt wear, leading to serious consequences.

The remaining material on the belt conveyor will increase the friction force on roller, sometimes it may cause the tear on the rubber surface of belt conveyor and also the layer of roller encapsulate. If the cleaning device can function well, it can prolong the service life of the roller, belt conveyor and etc.. This shows that the cleaning device has a significant effect on belt conveyor. In the process of operation, if you want to clean the sticky material on the tail bend pulley through anthropogenic removal, it often prone to serious bodily injury or death. Hence, in order to ensure the normal operation of the belt conveyor, the sticky material must be cleaned up by cleaning device before materials enter into the snub pulley.

 

Troubleshooting of Mining Belt Conveyor

 As the development of the conveying technology, belt conveyor used for mining industry also changed rapidly, adding many new functions. These new functions provided convenience for the user's operation and maintenance. Mining industry are mostly make multiple machineries work together to complete the handing task. If improper operation or material blocking caused the conveyor stop working, the motor will prone to be overloading and making abnormal sound. At this time we should shut down the conveyor immediately and examine the conveyor to find out the failure reason.

   Because mining industry has more complex situation the machinery will be prone to cause problem, if we can’t find out the problem promptly then will bring a greater loss, so Mining Belt Conveyor should be installed a sensor in the right place. When a trouble happens on Mining Belt Conveyor, such as motor burning, transmission part damaged, belt or chain fracture, belt slipping,

 

  we should design and installed some sensor or control switch with the shut down and control function, so that when trouble happens the sensor switch will give out the signal of shut down the conveyor automatically and also give out alarm. It not only reduces the damage caused by the trouble but also find out the trouble part promptly save the maintenance man lots of time.

    Here we want to emphasis the take-up device of the belt conveyor. It is well known to us that the operation of thebelt conveyor should maintain proper tension, if the belt become sag and can’t meet the required tension, the belt will be prone to slipping on the transmission pulley. Providing that we can’t adjust the belt promptly, it not only affects the conveying efficiency but shorten the useful life of the belt. The take-up device of the belt is designed to make the belt up to the required tension to avoid belt slipping on the drive pulley and guarantee the deflection between idlers in the specified range. The new belt and the belt using after a certain time is different in the length and tension, so we should adjust the take-up device promptly.

       Mining Belt Conveyor is mostly work with multiple machineries, so the control and operation of the machinery are usually adopt intelligent controlling and remote monitoring technologies. Thus, when the trouble happens on the machinery, the automatic alarm device on the conveyor will give out signal to the operator promptly, then the operator can use the feedback information to find the trouble part directly and begin repair the trouble part. It not only saving the operator’s time of finding the trouble but also minimize the damage of the users caused by theconveyor shut down. 

Belt Conveyor Maintenance

The maintenance schedule for any conveyor can be divided into three stages:1.    Belt shut down and empty2.    Belt running empty

3.    Belt running loaded

(i)           Belt Shut Down and Empty

This is the 1^st step in inspect the conveyor belt because this allows the opportunity to check any damage to the belt or splice. The conveyor should be locked out while making this inspection.

Rubber belt damage should be repaired using the hot vulcanized repair method or the cold repair method. Belt fabrics that are exposed to the weather or to product contamination should be properly cleaned, dried then covered with new rubber. These repairs are critical to prevent moisture from penetrating the belt and breaking down the cover adhesions and to prevent product contamination from abrading the carcass and also breaking down the adhesions.

The splice can also be inspected and if damage in the splice is visible, it is suggested that the splice be repaired or replaced. This is also a good time to walk the conveyor and check the following components.

A)   Tail Pulley free from build-up and trapped material
B)   Tail Pulley damage
C)   Skirting in the loading area
D)   Impact Bed or Impact Idler damage
E)    Slider Bed clean and smooth
F)    Carrying Side Idler damage
G)   Carrying Side Self Trainers (operational and not tied off)
H)   Secondary Loading Stations (skirting, impact bed or impact idler damage)
I)    Tripper Frame damage
J)    Tripper Discharge Pulley – clean
K)   Tripper Bend Pulleys – clean
L)    Head Pulley and/or Drive Pulley (clean, check for worn lagging, re-lag Drive Pulley if rubber is old, worn, smooth and hard)
M)  Head Pulley cleaner or scraper – operational
N)   Head Pulley Snub – clean
O)   Return Idlers – clean and turning freely
P)    Bend Pulley – celan
Q)   Take-up – clean
R)   Return Side Self Trainers – operational and not tied off
S)    Damage to return side frame due to mistraining
T)   Plow or Scraper in front of Tail Pulley – operational.

The preceding list should be used as a guide when inspecting the conveyor while it is empty and shut down. Numerous items in the preceding list contained the words “clean or operational”. Pulleys or idlers that have build up on them will cause tracking problems. The same can be said for pulleys that have some of the rubber lagging worn off.

      Scrapers, plows and self-trainers must be operational to perform their tasks. Belt damage, pulley damage and tracking problems will result if these accessory pieces of hardware are not well maintained.

(ii) Belt Running Empty

The conveyor should be turned on and run empty. The purpose of this is to run the conveyor while running empty to check for any tracking problems, the system will need to be inspected under running conditions when loaded, because empty belts and loaded belts do not necessarily track the same way.

(iii) Belt Running Loaded
The next step in inspection process is to run the belt in a loaded condition. We will add a few new steps in the inspection process and repeat a few on the previous steps. The following is our check list for operating the conveyor while loaded:
A)   Tail Pulley – turning freely without bearing noise, product build up or carryback; belt tracking satisfactorily.
B)   Load area spillage
C)   Carry Side Idlers – turning freely
D)   Carry Side Self-Trainers – functioning
E)    Secondary Loading Station spillage
F)    Tripper Area (tracking and spillage)
G)   Head Pulley and or Drive Pulley (smoothly running, slippage when starting or running, belt cleaners – functioning, and belt tracking)
H)   Head Pulley Snub – turning freely without bearing noise and clean
I)    Return Idler – clean and turning freely
J)    Bend Pulleys – turning freely without bearing noise and clean
K)   Take-up Pulley – turning freely without bearing noise, clean, moving freely in the frame
L)    Return Side Self-Trainers – functioning
M)  General Belt Tracking
N)   Plow or Scraper in front of Tail Pulley – functioning

(iv) Corrective Action
The last step is to take the corrected action required on the conveyor in addition to: A) Clean Up
B) Lubrication
C) Safety concerns – such as installing or repairing conveyor crossovers, safety stop cables, holdbacks on incline conveyors, edge limit switches, motor guards, hand rails and etc.


A conveyor system with carryback on the return side is the single biggest reason that conveyor belts are replaced, return idlers and pulleys are replaced and structure is worn through. Material build up on the belt and hardware causes tracking problems that will lead to edge damage that leads to new belt and new idlers.

    We urge you to use scrapers on the head pulley and plows in front of the tail pulley as prevention for damage in your maintenance planning. Some sticky materials present a real challenge when it comes to preventing carryback. Cleated belts may be reversed to allow better release at the discharge point. A dual scraper system on the head pulley is the most common way to eliminate product carryback.

    A water spray on the belt cover along with wiper blades will effectively remove most products from sticking to the cover. A series of out of round (cam shaped) return idlers will also assist in cleaning. These idlers are spiral wound from the edges towards the center of the idler and work on the premise of a turning beater bar arrangement. A brush may be the only solution for cleated belts. If your belt is not effectively clean on the return run, then any bend pulley or head snub pulley that come in contact with the carry side of the belt will accumulate product.

    Henan Pingyuan would like to offer few hints on pulley and idler cleaning. All return side pulleys that come in contact with the carry cover can be lagged with a soft rubber vulcanized to the pulley. The constant flexing action of the soft lagging will cause material to fall off and reduce material accumulation.

    A lever weighted urethane scraper pressed against the pulley face, is an excellent way to remove build up. This system causes additional wear on the pulley face so it is suggested to use heavier walled return bend pulleys when using a scraper. If a scraper is applied to a head snub or bend pulleys at the take-up area, then deflector plates will have to be installed to deflect the build up away from the belt.

    Return idlers can be rubber covered and will help prevent product from sticking to the return idler. Return idlers can be purchased that are nothing more than disc mounted on a shaft. These discs can be made of soft rubber, urethane or ceramics. This type of return idler can be very effective to prevent build up.

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Henan Pingyuan Mining Machinery Co., Ltd is the most professional manufacturer of Belt conveyor, andVibrating screen, Bucket elevator, Screw conveyor, Scraper conveyor using the world's most advanced technology, we are willing to serve every company to meet your custom needs. our goal is "be the future global leader of mining machinery industry". have any questions, please contact us without any hesitation.

What are the Components of Belt Conveyor

1. Conveyor frame parts
Including: head frame, tail frame, intermediate frame and supporting leg which are produced by cutting, welding, punching and polishing with standard channel, angle iron, steel and other.
2. Composition of other components:
i. Roller
Roller has the highest quantity and is the most carrying parts of belt conveyor. Impact roller, friction centering carrier roller, belt conveyor roller, and so on are included. The lifespan of roller is depends on the usage, usually the roller needs to be replaced every one to two years.

ii. Drum pulley 
Power conversion device and redirection device of belt conveyor including the drive pulley and return pulley. It is durable but the bearings need to be lubricated.

iii. Conveyor belt
It is one of the most expensive parts of belt conveyor, and also an important part to carry the materials. Hence, it needs to be maintained properly.
iv. Driving device
It is the power source of belt conveyor. Commonly motor works together with reducer, however, motorized pulley can also be used. 
3. Cleaning device
Including : head cleanser, non-loaded cleanser, tail cleanser, spring cleanser and so on.

4. Protection device
Including : pull-cord switch, running deviation switch, skid detector and so on.

5. Electronic control device: 
Including: electric cabinet, power protection device.
All the parts mentioned above are needed to ensure the normal operation ad production of belt conveyor, hope this article is helpful!

 

What Should We Note During the Installation of Large Angle Belt Conveyor

Large angle belt conveyor can be transported with large inclination , it even can be vertical. It adopts sidewall belt as the main part. The advantages are: large conveying amount, small space occupation ,small noise etc. which is widely used for conveying powder, blocked material. Here PK Machinery will introduce the installation notes during installation:
1.Check whether the components of large angle belt conveyor are complete or not
Generally speaking, belt conveyor includes lots of components: head & tail frame, concave & convex segmental arc frame and middle frame, however, the quantity of trough roller frame, rollers and sealing cover is big, you need to check carefully and guarantee the components are transported to the right place.
2.Installation, positioning and welding of head and tail frame, concave and convex segmental arc frame
First of all, please find the center line of the belt conveyor by using a steel wire. When installation, please make the head & tail frame, concave & convex segmental arc frame subject to the center line.

3.Check belt running and adjust the belt if it runs off tracking
After installation of belt, trough roller, self-aligning roller and vertical roller, connect the power supply , run the belt and adjust the belt offset distance .
4.Installation of large dip Angle belt conveyor accessories and bolts
After adjusting the belt, you can start to install the sealing cover, head cover and fastening bolts.

Features and Maintenance of Portable Belt Conveyor

Features:

1.Portable belt conveyor can work in any applicable site , and avoid operating in rainy day.

2.Because of its good performance so that you can directly for loading and unloading car, material handling, etc.

3.Easy to operate, no need for manual duty and start work once boot.This machine is equipped with electric control box which contains a master switch and a lift the switch.

Maintenance:

1.Avoid operating in damp environment and rainy day as much as possible to protect machine body from rust damage.

2.Regular check to ensure smooth running direction, to avoid the unnecessary loss due to conveyor belt running deviation.

3.Regular check the fasteners of machine body to ensure the bolt tension equipment in good condition. Add lubricating oil in time to ensure that the bearing lubrication. Regular check roller and other replacement of damaged parts to ensure the normal use of belt conveyor.

Three Horizontal Sections of Large Angle Belt Conveyor

Large angle belt conveyor is suitable for the unit mass of 500 ~ 2500 kg/m3 and the material large size of about 100 ~ 250 mm, the features of large angle belt conveyor are: simple structure, convenient maintenance, space saving and investment saving. Here PK Machinery will explain and introduce three kinds of horizontal section:
1. Upper horizontal section
In order to adapt to the requirement of different discharge height, the head frame is divided into low type frame (head frame height = 1000 mm), middle type head frame (head frame height = 1100 ~ 1100 mm) and high type head frame (head frame height = 1600 ~ 1600 mm).
Correspondingly, low type convex segmental arc frame and low type middle frame support (matched head height = 1000 mm), middle type convex segment frame and middle type frame support (matched head frame height = 1100 ~ 1500 mm), high type convex segment frame and high type middle frame support (matched head frame height = 1600 ~ 1600 mm) will match with upper horizontal section respectively
2. Lower horizontal section
The lower horizontal section adopts low type middle frame support.
3. Inclined section
The inclined section of large angle belt conveyor adopts low type middle frame support. When the conveyor inclined angle β ≧ 45 °, we suggest adopting Ⅱseries low type middle support.

The connection of upper horizontal section and inclined adopts the convex arc segments frame , and the lower horizontal section and inclined section adopt concave segmental arc frame to connect so as to realize the smoothconveyor belt transition.

Why will Belt Conveyor Motorized Pulley Get Rusty

During the operation process of belt conveyor, it will occur some problems due to incorrect method of using or wear and tear, therefore, we need to know some knowledge in order to ensure the normal operation. Here PK Machinery will list some reasons why motorized pulley of belt conveyor will rust:
1. Electroplating time is not enough, it dues to the problem of process flow;
2. Air liquidity of the location where motorized pulley stores is not good, or the location is wet, it is may due to the large difference in temperature;
3. If the package sealing breaks, the motorized pulley may oxidate and get rusty;
4. The most important point is that before electroplating, the dirt on motorized pulley surface is not being cleaned well, it is also one of the reasons why the motorized pulley will get rusty.

 

How to Prolong Working Life of Belt Conveyor

    Belt conveyor widely used in mining, metallurgy, coal, fertilizer, chemical, cement and other industries. The usage of belt conveyor is to convey bulk materials or pieces materials to another location according to different transferring requirements. The conveying systems can comprised only one belt conveyor or several conveyors or combined with other conveying equipment. The belt conveyor can be installed horizontally or incline to satisfy the clients requirements.  

 The reliable operation of belt conveyor is vital in industries. The risk of failures in operations needed to be eliminated. The technical team or mechanical workers should do inspection regularly and pay attention to the case or parts. The conveyor belt life span can be extended up to 4 times if transfer points are controlled correctly. The conventional chute systems or transfer points generally drop the material from point A to point B.  The height of the drop normally is not taken into account however this is the most critical factors that affect belt conveyor lifespan. The dropping products with lump sizes up to 500 mm directly onto an outgoing conveyor belt will create a massive impacts and resulting in belt damage over a short period. 
    Besides, the foreign objects which move through the systems also affect the life span of belt conveyor. When a new underground mining operations are being established, there are some foreign objects such as concrete, iron, pillars and steel ropes may fallen on the belt conveyor. This normally will cause blockages or stoppages. Controlling the flow of materials onto conveyor belt is to reduce impact has become a topic for discussion and numerous solutions being proposed. There are a lot information are needed to design on a transfer point which satisfy the proposed concept. The information includes product type and consistency, conveyor trajectory angles, transfer height and distance.   
    Just obtaining this information is not sufficient, it is necessary to do an on-site assessment to verify the data. This enable engineers to tackler other issues which could be causing impact damage on the belt conveyor. In addition, uneven conveyor belt loading, flooding of the belt and blockages could cause damage too. A good design of belt conveyor can prolong the life span and increase the efficiency of the operation. 

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Henan Pingyuan Mining Machinery Co., Ltd is the most professional manufacturer of Belt conveyor, andVibrating screen, Bucket elevator, Screw conveyor, Scraper conveyor using the world's most advanced technology, we are willing to serve every company to meet your custom needs. our goal is "be the future global leader of mining machinery industry". have any questions, please contact us without any hesitation.

Necessity of Belt Cleaner

Belt cleaner is a scraper for the belt conveyor. Belt conveyor is used to transport raw materials of ironworks industry, mining, fertilizers, power stations and etc. Normally after conveying raw materials, fine powders and mud often stick on the surface of the belt conveyor. This can cause numerous problems of adhesion to peripheral equipment, meander of belts, falling products and deterioration of work environment. All this problems can be fixed by a belt cleaner. Belt cleaner can prolong the life of belt conveyor, improve working environment, effective utilization of resources and cost reduction. 

A belt cleaner consists of a pre-cleaner and a T-cleaner (Secondary Cleaners). The pre-cleaner or known as primary cleaners has excellent abrasion resistance and uses polyurethane blades which are friendly to conveyor belt. It always keeps optimum surface pressure by spring-tensioned structures and there is no troublesome tension adjustment. It can be replaced safely in short time by aluminium cassette system. The T- cleaner uses super hard chip for blade materials which is excellent of abrasion resistance, long life span and low running cost. It always keeps optimum surface pressure by spring tensioned structure just like pre-cleaner. The tensioner can be set on inside and outside of shoot. It is easy to select space for setting. It also can be replaces safely in short time by aluminium cassette system. 

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Henan Pingyuan Mining Machinery Co., Ltd is the most professional manufacturer of Belt conveyor, andVibrating screen, Bucket elevator, Screw conveyor, Scraper conveyor using the world's most advanced technology, we are willing to serve every company to meet your custom needs. our goal is "be the future global leader of mining machinery industry". have any questions, please contact us without any hesitation.

Please Focus on Belt Speed Selection and Principle of Belt Conveyor

As we all know, the most decisive factor of belt conveyor throughput is the belt speed, here we would like to introduce the selection method of belt conveyor belt speed:

(1) If the conveying capacity of belt conveyor is large, belt width is wide, please select a high belt speed.
(2) If the material is easy to move with big granularity and strong grinding property, please select a low belt speed.
(3) If material conveying interval is long, please choose a high belt speed; If material conveying interval is short and the conveyor angle is big, please select a low belt speed.
(4) If there is large amount of dust during conveying, the belt speed would be 0.8 m/s ~ 1 m/s.
(5) If belt conveyor works with a discharging tripper, the belt speed should not be higher than 2.5 m/s.
(6) If belt conveyor conveys finished product items, the belt speed should be less than 1.25 m/s.

Belt speed selection principle of belt conveyor : the belt speed of belt conveyor is related to belt width, throughput, material size, material properties and conveyor angle. When belt conveyor transports upward and dip angle is large, the tape speed should be low; When belt conveyor transports downward, the belt speed should be much lower. Belt speed selection also should match the cooperated material discharging equipment type, when adopts plough type discharging machine, the belt speed should not exceed 3.15 m/s.

Hazards and Safeguarding Methods of belt conveyor

Typical Conveyor Hazards and Safeguarding Methods

Belt Conveyors

Hazards:

•Belt conveyor drive mechanisms and conveying mediums

•Conveyor take-up and discharge ends

•Where the belt or chain enters or exists the in-going nip point

•Where the belt wraps around pulleys

•Snub rollers where the belt changes direction such as take ups

•Where multiple conveyors are adjoined

•On transfers or deflectors used with belt conveyor

Hazard Controls:

-Nip and shear points must be safeguarded

-Side guards (spill guards) can prevent contact with power- transmission components, in-going nip points and the conveying medium

-Secondary safeguards include railings or fencing or safeguarding by distance (location) and hazard awareness devices such as pre start-up signals and warning signs. 

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Henan Pingyuan Mining Machinery Co., Ltd is the most professional manufacturer of Belt conveyor, andVibrating screen, Bucket elevator, Screw conveyor, Scraper conveyor using the world's most advanced technology, we are willing to serve every company to meet your custom needs. our goal is "be the future global leader of mining machinery industry". have any questions, please contact us without any hesitation.

How to Solve Portable Belt Conveyor Belt Skid Problem

Portable belt conveyor is a lightweight continuous conveying equipment with the features of high efficiency, good mobility, and convenient usage. It not only conveys bulking material but also realize conveying bagged material, the angle and lifting height is adjustable. In our daily life of operation, we may have trouble of belt skid problem, today PK Machinery will introduce the method to solve the problem:

1.You can adjust the stroke of tension to increase the tension to solve belt skid problem for the portable conveyor which adopts screw or hydraulic tensioning . However ,if the stroke of tension is not enough, it may lead to permanent belt deformation ,and you need to cut a piece of belt off and vulcanize again.

2.If you require long stroke of tension when using nylon or EP belt, you can also vulcanize the belt or increase the stroke of tension to solve belt skip problem.

   -------------------------------------------------------------------------Henan Pingyuan Mining Machinery Co., Ltd is the most professional manufacturer of Belt conveyor, and Vibrating screen, Bucket elevator, Screw conveyor, Scraper conveyor using the world's most advanced technology, we are willing to serve every company to meet your custom needs. our goal is "be the future global leader of mining machinery industry". have any questions, please contact us without any hesitation. 

portable belt conveyor

In today world, portable belt conveyor is an another type of great innovated machinery equipment because of it mobility, it has bring a lot of convenience to human especially in production site.

It has the features of high efficiency, good mobility, and convenient usage.

It is also a lightweight continuous conveying equipment 

However, portable belt conveyor is widely applied in port, jetty, mining, warehouse, and construction site for moving materials from one place to another places..

For more information please visit : http://www.pkmachinery.com/belt-conveyor/portable-belt-conveyor.html

Protective Device’s Type and Function of Belt Conveyor

 There are some protective device inside the belt conveyor to prevent accidents and ensure the safety when conveying materials. Protections of belt conveyor consist of belt sway protection, belt-broken protection, sliding protection and emergency stop pull switch. Belt sway, belt-broken and sliding protections are course switch with simple structure and low cost, the working principle is that the machine would stop when belt touched switch. Emergency stop pull switch rely on an electric switch and pulls the steel cord wire installed on both sides of the belt.

Speed sensors: using hall elements to detect the speed of belt conveyor. If the speed of driven wheel is in 50%-70% Va, or the speed of belt conveyor is less than or equal 50% Va or greater than or equal 110% Va, and after 5-10 seconds delay, the controller would cut off the power source automatically to protect the speed.

Disalignment transducer: be off-state in normal, and close when operation. It will cut off the power source automatically to stop belt conveyor.

Coal blocking transducer: breakover by two electrodes, through leads give the reaction of coal volume to protective device. It monitors the coal volume in bucket and bunker, and will cut off the power source when bunker is full or coal piling in machine head to achieve protection. 

Scram protection: there is pull urgent stop switch installed on the control panel of each controller and the belt side, used in emergency stop when trouble.   

Overtemperature protection: uses a temperature senor to monitor the temperatures of bearing and other parts of belt conveyor and environment temperature. When the temperature of the monitoring points is more than the set value, the controller will cut off the power source automatically to protect the machine and start sprinklers to cool.

Smoke transducer: when detects the smoke produced, the controller will cut off the power source and start the dust extinguishing sprinkler device. 

Rip transducer: when the belt has longitudinal tear problem, the coal falls on the sensor, and the controller will cut off power source to stop the belt conveyor. 

Safety protection device of belt conveyor is used to monitor and give alarms when happens troubles in operation. It can make the conveyor system safety production, proper operation and protect the safety of operating personnel. Besides, it can also facilitate centralized control and improve the level of automation.

Common protection and monitoring devices are as follows:

Longitudinal tear protection device: used to detect the belt conveyor. When there are material sharps in conveyor and the belt torn from middle, the controller will cut off power source.

Belt sway switches: used to detect the conveyor belt running deviation and distortion degree, can prevent edge damage and materials diffused to realize automatic alarm and stop the machine. A  warning signal when the mild deviation, delay action, alarm and automatic shutdown when severe deviation. Generally installed in the head, middle, tail and inspection points of the belt conveyor.

Pull switch: it is a protective device for conveyor-site emergency stop when an emergency occurs, anywhere in the field to pull the switch, can be a warning signal, and then self-locking and stop. Generally pull switch mounted on both sides every 60m of belt conveyor.

Chute block switch: used to detect chute blockage of belt conveyor system. When occurs blockage, the controller will give an alarm and shut down. 

Slip detector: used to detect the difference of linear speed between shaft belt and driving idler. It can give an alarm and achieve automatic tension and normal shutdown.

Overspeed detection device: used for downstream transport or transported under conditions. When the conveyor speed reaches 115% -125% of the specified belt speed, it will give an alarm and emergency stop.

Maintenance Method of Portable Belt Conveyor in winter season

In winter, portable belt conveyor will work in the outdoor and suffer from rain and snow, in this way, what shall we do to maintain portable belt conveyor to achieve the purpose of long-term steady operation?

1. Maintenance of motor
Concerning the operation process of portable belt conveyor in winter, motor will be the main part we should protect. Although motor damage rate is very low, if motor overloads it will still damage. As we all know, temperature is pretty low in winter, motor lubrication condition is not very good. Therefore, the motor of portable belt conveyor should be checked and maintained regularly .

2. Overall antirust processing for the whole machine
Though before leaving factory, portable belt conveyor was already painted again and again, after checking, we found that most of the conveyors are still rusty. This is not the problem of painting, but the problem of not paying attention to maintenance of equipment, especially in the winter, there is lots of rain and snow, in many cases, these portable belt conveyor will be in the rain and snow without being covered. So in the long run, even using the best painting and steel ,the portable belt conveyor will still reduce the service life. 
In conclusion, the suggestion is to make the conveyor covered and keep the conveyor away from rain and snow to improve the service life.

3. Maintenance and replacement of spare parts
Conveyor roller is the most used spare parts of portable belt conveyor, so we need to check the wear condition and bearing using condition of roller frequently. Concerning the damaged roller, you should replace timely.
For conveyor belt, please clear up the belt surface and the accumulated impurities timely in order to avoid long time abrasion.