In the process of using nylon conveyor belt, the phenomenon of rubber layer aging and shedding is simple. Baoding Hangda Rubber Belt Co., Ltd. has discussed the factors that cause rubber aging in the following aspects:

1) Oxygen: Oxygen reacts with the free radical chain of rubber molecules in the rubber, and the molecular chain is cracked or excessively cross-linked, causing the rubber function to change. Oxidation effect is one of the important reasons for rubber aging.

2) The chemical activity of ozone and ozone is much higher than that of oxygen, and it is more damaging. It also causes the molecular chain to crack, but the effect of ozone on rubber varies with whether the rubber is deformed or not. When the effect is on deformed rubber (mainly unsaturated rubber), cracks that are perpendicular to the direction of the stress effect appear, so-called "ozone cracks"; when the effect is on deformed rubber, only an oxide film is formed on the outer surface without cracking.

3) Heat: Increasing the temperature can cause thermal cracking or thermal crosslinking of the rubber. But the fundamental effect of heat is still the activation effect. Increase the oxygen diffusion rate and activate the oxidation reaction, thereby accelerating the rubber oxidation reaction speed, which is a common aging phenomenon-thermal oxygen aging.

4) Light: The shorter the light wave, the greater the energy. The damage to the rubber is the higher energy ultraviolet rays. In addition to ultraviolet rays can directly cause the cracking and cross-linking of the rubber molecular chain, the rubber generates free radicals due to the absorption of light energy, which initiates and accelerates the reaction process of the oxidation chain. Ultraviolet light has a heating effect. Another feature of the light effect (different from the thermal effect) is that it mainly grows on the outer surface of the rubber. Samples with high gel content will show network cracks on both sides, the so-called "light outer layer cracks".

5) Mechanical stress: under the repeated effects of mechanical stress and the continuous friction process between the conveyor belt and the idler roller, the rubber molecular chain will crack and generate free radicals, trigger the reaction of the oxidation chain, and form a mechanochemical process. Mechanical cracking of molecular chains and mechanical activation of the oxidation process. Which one can prevail depends on the conditions in which it is located. In addition, it simply causes ozone cracking under the effect of stress.

6) Moisture: The effect of moisture has two aspects: rubber is simply damaged when it is exposed to rain or immersed in water in humid air. This is because the water-soluble substances and clear water groups in the rubber are extracted and dissolved by water. Caused by hydrolysis or absorption. Especially under the alternating effect of water immersion and atmospheric exposure, it will accelerate the damage of rubber. However, under certain conditions, moisture has no damaging effect on rubber, and even has the effect of delaying aging.

7) Others: The effect factors on rubber include chemical media, variable metal ions, high-energy radiation, electricity and biology.

What are the ways to improve the service life of heat-resistant conveyor belts? Here are some conveyor belt manufacturers to introduce to you, I hope our introduction can help you better.

1. In the industrial and mining transportation industry, heat-resistant conveyor belts are a common product and a very important part. However, in actual use, there are many reasons for the tearing of the tape. We choose ordinary canvas belts instead of steel cord core belts. Or synthetic fiber belt, the guide groove design should be convenient for bulk materials to pass, etc. Most conveyor systems should also be equipped with a tear detection system. When the conveyor belt is torn, it can be detected in time. Stopping the conveyor can reduce the conveyor belt. Of tearing. The heat-resistant conveyor belt is a kind of consumable, which is a part of the belt conveyor. It runs through the entire length of the conveyor. It is not only used in large quantities, but also expensive. The conveying rubber is composed of upper and lower covering rubber and belt cores. The reason for the longitudinal tearing of the heat-resistant conveyor belt. The vibration and impact cause the fasteners to loosen and fall off, forming the falling coal pipe liner, the guide plate, etc. , The roller is defective, the roller frame is scratched, and the conveyor belt is hung by the frame after severely running off.

2. The main reason for the cracking of the conveyor belt is that due to the limitation of the space scale, the conveyor belt has many twists and turns; the joint vulcanization has been vulcanized more than twice due to various reasons. The gap between the guide chute liner and the tape is inappropriate, resulting in abnormal wear, or foreign objects embedded in the gap, resulting in abnormal wear or scratches. The flow rate of the material at the guide trough is inconsistent with the speed of the conveyor belt, and the drop is large, which accelerates the wear of the rubber surface. The roller is damaged, causing abnormal wear or scratches of the tape. Slippage of the tape will also cause abnormal wear of the tape. When our factory detects heat-resistant conveyor belts, tearing causes the detection of external behavior changes. The detector uses the material that leaks out after the heat-resistant tape is torn, and triggers a protection switch to instruct the conveyor to stop, although external testing equipment can prevent Tear, but it still cannot fundamentally protect the conveyor belt. We must pay attention to this aspect in actual use.

In all occupations, preventive protection is important to reduce the risk of problems. The conveyor belt is no exception. I often encourage customers to check their conveyor belts to avoid problems in production and to avoid unnecessary damage to their equipment. The following are some tips on preventive protection of conveyor belts that you can implement by yourself.

1. Preventive protection of conveyor belts

Preventive protection includes a detailed inspection of the machine to see if there are faults or parts that are dangerous to use due to wear. Early detection, early know and early treatment. It is easier to make corrections and adopt methods to avoid future production problems. And optimize the service life of the conveyor belt.

Need to pay attention to some of the problems that may appear are: the conveyor belt is not running straight, the roller is blocked, the bearing is damaged, the fabric is damaged, or the conveyor belt is often stuck or slipped. These conditions do not necessarily mean that your shipping belt is damaged. However, when the machine fails, it is often considered to be a problem with the conveyor belt, but it may also be a problem caused by the bearing or other parts of the conveyor itself. If the conveyor belt seems to be in good condition, but the problem still exists, you should carefully check all parts of the machine.

2. How to perform visual inspection

The value of regular eye checks cannot be overstated. By simply viewing the visible surfaces and parts, you can save your company time, money, and labor.

There are four specific questions you should ask when looking for damage to the shipping belt.

1. Is the conveyor belt complete?

First look at the transport belt itself. Whether the conveyor belt is damaged. Are the conveyor belt joints in good condition? Are the pulleys, rollers, bearings, and profiles normal? For example: Worn bearings may be the cause of the conveyor belt running to one side.

2. Is the conveyor belt centered on the roller?

The conveyor belt should be centered to achieve product transportation. Check if it is accurately positioned between the rollers. Also make sure that the pulleys, wheels and rollers are installed and aligned. If not, the conveyor belt may start to run sideways.

3. Is the conveyor belt able to transport products adequately?

How does the conveyor belt behave during operation? The conveyor belt may work well when empty, but then starts to slide under the weight of the load. If the conveying belt slips or conflicts at a certain point, the heat generated by the conflict will be generated, and the data of the belt will begin to melt. Therefore, the conveyor belt is adjusted under both no-load and load conditions.

3. Is the conveyor belt clean?

Some conveyor belts pay more attention to hygiene than others, such as food conveyor belts. Therefore, it is very important to clean the conveyor belt and its frequently touched parts. Uneven surfaces, cracks or cracks are places where bacteria may multiply. Dirt and substances entering the conveyor belt may cause product contamination. Therefore, you should always check and clean the transport belt carefully.
To
Four, check frequency

How often you need to check the conveyor belt depends on many factors: the type of application, the environment in which the conveyor belt runs, the size of the load, and the frequency of use of the conveyor belt. There are many applications, conveyor belts and carriers that operate in harsher environments at extreme ambient temperatures, such as ovens. Other conveyor belts transport very heavy products or products that contain toxic chemicals. Some need to tolerate strong detergents.

In recent years, corrugated sidewall belt conveyors have been widely used in grain, coal, port, electric power, metallurgy, mining and chemical industries. For example, corrugated sidewall conveyors used in ironmaking blast furnaces consist of frame, body, Conveyor belt, concave and convex arc section roller set, arc section pressure belt wheel set, in the concave arc section can be 70 to 90 degrees of large angle changes, and then through the convex arc section of the angle change, the material can be Nearly vertical transportation from the storage place to the destination.

When the belt change angle of the rib belt conveyor increases, due to the large conveying angle, when a press belt wheel set is used, the radius of curvature of the rib belt is the radius of the press belt wheel set, and the range of the change angle decreases. This results in a sudden change in the angle of the sidewall tape, so that the material in the sidewall rubber conveyor belt cavity will fall due to the sudden angle change, which reduces the operating efficiency of the belt conveyor.

In order to solve the problem that when the conveying angle of the corrugated side belt conveyor is large, the material in the side rubber belt cavity falls, and at the same time, in order to improve its production efficiency, reduce the pressure that the pressure belt wheel group bears during the conveying process, To extend the service life of the sidewall belt and conveyor parts, the Kunshuo industrial conveyor belt manufacturer can completely meet the above requirements through a new structure of the sidewall belt conveyor. This set of conveyor equipment is mainly composed of racks and sidewall belts. , Roller set, and pressure roller group, in the concave arc section: the diameter of the pressure belt wheel group and the pressure belt wheel are the same, and their centers are located on both sides of the angle bisector formed by the concave arc section rib tape at the variable angle , And fixed on the conveyor frame through the bearing seat. When the angle of the sidewall of the belt conveyor increases, for example, when it reaches 90 degrees, the pressure pulley group first changes the angle of the sidewall conveyor from 0 to 45 In this way, the material in the ribbed cavity has a good cushioning effect during the angle change process, thus avoiding the wavy rib conveyor belt cavity from 45 degrees to 90 degrees. Falling out improves the efficiency of the belt conveyor.

It can be seen that when two sets of pressure rollers are used, the combined force of any set of pressure rollers is 0.6 times the belt tension, which is much smaller than the combined force received when using a set of pressure rollers. When the conveying capacity reaches 500 tons per hour, the lifting height can reach 35 meters, and the operation efficiency is extremely high.

The idler in the belt conveyor machinery is mainly used to support the conveyor belt and reduce the running resistance. Due to its different assembly form, it will affect the conveying capacity of the conveyor. In addition, the idler is a large number of parts in the belt conveyor. Its structure, shape and assembly method have a great influence on the normal operation, use effect, production investment and operating cost of the belt conveyor.

The number of beams of the individual rollers in the branch roller group on the belt conveyor is different. At present, the common one is a group of three. The assembly structure of the upper branch roller group is generally trough type, which is mainly caused by It is composed of three rollers of equal length. This form is mainly used to reduce the impact of the bulk material on the supporting rollers on both sides when conveying bulk materials, so as to extend the service life of it and the industrial transportation belt. At the same time, the structure of the supporting rollers is also considered. Uniform form and interchange in use, but this isometric structure does not consider the impact of materials with different accumulation angles on the conveying capacity of the belt conveyor. It is conveying granular materials such as pulverized coal, grains, sand and chemical products. At this time, we should improve the conveying capacity of the belt conveyor and prolong the service life of the idler. Therefore, it is necessary to start from the length of the intermediate idler to analyze the influence on the conveyor capacity of the conveyor to find the use length of the intermediate idler of the conveyor belt. .

As far as the conveying capacity of the conveyor is concerned, the length of the intermediate roller should be appropriately shortened, and the advantages of shortening the length of the intermediate roller, in addition to improving the conveying capacity, can also reduce the load borne by the intermediate roller, thereby extending it When the groove angle of the side roller is 30 degrees, the load on the middle roller is 70% of the total load, and the load on each side roller is only 14.5% of the total load. , It can be seen that when conveying large materials such as raw coal, it is more reasonable to use equal-length rollers, but for conveying granular materials such as pulverized coal, grain, sand and chemical products, a shortened intermediate roller is used. The length is reasonable.

The length of the intermediate roller will gradually decrease with the increase of the dynamic accumulation angle of the material and the increase of the groove angle of the side roller. When conveying bulk granular materials, if the required industrial conveyor belt bandwidth is not too large, it can be known that The range value between the intermediate rollers, so if the belt width you need is less than one meter, including one meter, you can appropriately widen the gap between the two rollers and cancel the intermediate roller to form a double roller group. The existing belt conveyor adopts a double roller set for this reason. The load on each roller is smaller than when three rollers are used, and the service cycle will increase accordingly.

Due to the continuous increase in the use of mining materials, the corresponding mining scale is constantly increasing. During the production process, it is necessary to ensure the normal operation of the work. Therefore, the requirements for the stable operation of the sidewall belt conveyor are also very important. We will use the belt below. The more stable operation of the machine is explained in detail.

Belt conveyors are indispensable in mining: they have the advantages of large capacity, long transmission distance, continuous transportation, etc., and can be automated and remotely controlled. Therefore, conveyor equipment has a wide range of applications, but with the rapid level of technology automation The increase and the increase in the number of mining have a higher demand for operation requirements and efficiency. In the operation and production process, a large inclination and long-distance belt conveyor machine with higher operation intensity has been invested. The current large inclination can reach 50 degrees, but it is increasing. At the same time of large inclination, special attention must be paid to the operation stability of the equipment. In addition to the equipped brake equipment, a scientific and reasonable layout is also required to make the belt conveyor equipment operate more stably.

If the belt conveyor stops transporting a large amount of mineral materials, there will be materials attached to the skirt conveyor belt, and the sliding force will cause the whole machine to slide backward, which will cause abnormal accidents. To avoid such problems, reliable protection must be configured. Inverter, this can ensure the stable operation of the large-incline belt conveyor. The prerequisite for the selection is to measure the sliding moment of the conveyor at the time of working capacity. Within ten meters from the loading point to the front of the operation, the installation angle of the tailstock and the middle frame of this section is reduced to less than 30 degrees, so that the installation angle of the whole machine is smaller than the dynamic dumping angle of the raw materials, so that the materials are waiting to be loaded. After stabilizing on the rubber belt, enter the operating condition of large inclination.

In order to avoid the problem of belt slippage when the belt conveyor is in use, a high-strength flame-retardant pattern steel wire rope core tear-resistant conveyor belt can be selected to increase the frictional resistance between the belt surface and the belt body is laid flat in a deep groove shape. For the roller group, the upper groove angle of the misaligned roller can be selected to be 60 degrees to increase the lateral squeezing force between the material and the wire rope conveyor belt and prevent the whole machine from spattering during use. According to the sidewall belt conveyor The carrying capacity needs to be equipped with an appropriate loading mechanism, and then use the hopper to select an appropriate angle according to the site conditions. The chute is designed into a spoon shape, and the blanking direction is changed to horizontal. This can ensure smoother conveying and reduce the impact on the belt. .

In addition, choose a suitable frequency conversion soft start method, and set a closed protective device on the upper belt to prevent the material rolling due to excessive inclination. A closed scraper is placed in the middle of the lower belt to prevent the material from rolling towards the machine. These tails are very important to the smooth operation of the conveyor. Reasonable protection of the tail can prevent abnormalities such as misalignment of the belt caused by debris and stones, and damage to the broken belt. We can completely seal the tail.

Increase the storage capacity to reduce the frequent operation of the belt conveyor, avoid overloading operation, strictly control the moisture of the material, prevent the mixing of water in other production and transportation links, repair the belt pattern wear, after technical analysis and field observation, the large inclination belt conveyor Due to the frictional resistance between the material and the non-slip rubber conveyor belt when running at a constant speed, the rapid increase in the sliding speed will cause the pattern part of the industrial rubber belt to wear. If it is not repaired in time, the belt will not be able to convey the material. Therefore, professional rubber should be used. Repair in time such as cold sticking method;

1. Chemical cleaning, use professional mold washing water, or diluted sulfuric acid to directly clean the scaled parts. This method is fast and the effect is also acceptable, but it will produce pungent odors during cleaning, and it will also pollute the environment. This method has been gradually eliminated, and some small processing plants are still in use.

2. Mechanical descaling. At present, most rubber product manufacturers are equipped with sandblasting machines, which can directly blast the surface of the mold with resin sand. This method has a better cleaning effect and is a more commonly used method of mold cleaning.

3. Ultrasonic descaling, using the principle of frequency and wavelength to shake off the dirt in the mold cavity. The effect is better when used with mold washing water. This effect is very good, but the cost is relatively high.

4. Mold electroplating, plating the surface of the mold with a layer of hard chromium. Practice has shown that this method can effectively solve the adhesion of deposits on the surface of the mold. This method is more suitable for mass rubber product molds.

1. Rubber product mould

1) When designing the rubber product mold, it must be easy to demold, accurately conform to the contour and shape of the rubber product, and the structure must be simple, reasonable, and easy to operate to meet the technical requirements;

2) The mold should be maintained frequently to observe its cleanliness, whether it is deformed, whether the positioning is firm, whether the surface is smooth, etc.

2. The structure of rubber products is unfavorable. When designing rubber products, attention should be paid to its shape, thickness, and demolding slope, among which the demolding slope is the main factor. After the product is out of the furnace, the product cools and produces a centripetal shrinkage, which produces a large holding force on the core or pin, thereby hindering the demolding. If the demolding slope is increased, this resistance can be significantly reduced, and defects such as tearing of the product due to no slope can also be avoided.

3. Unreasonable product formulation. Insufficient vulcanizing agent and accelerator in the formulation, or unreasonable vulcanization temperature and time design, resulting in insufficient sulfur; or too much raw rubber rubber content, too much accelerator vulcanizing agent, etc., will also cause difficulty in demolding.

4. Production process In the production process of rubber molded products, injection pressure, holding pressure, vulcanization temperature, vulcanization time, etc. will also affect the difficulty of demolding. For example, if the injection pressure is too high, the mold parts will be elastically deformed and cause extrusion force. If the holding pressure injection force is too high and the time is too long, it will cause the pressure in the cavity to increase, generate greater internal stress, and cause deformation or deformation of the mold parts. Flashing occurs between the mating surfaces, making demolding more difficult.

The second is the demoulding method. Through the analysis of demoulding factors, we can use the following methods to avoid or solve the problem of difficult demolding.

1. The mold structure is reasonable, and the mold rigidity is improved as much as possible; timely maintenance of the mold, such as cleaning (plating, PTFE spraying, sandblasting), etc.

2. The structure design of rubber products should be easy to demould and have enough slope. 3. Choose a reasonable and appropriate viscosity formula. Properly adjust the vulcanization system, especially rubber products, increase the amount of accelerator; add carbon black for reinforcement or adjust the original formula.

4. If the vulcanization is unfamiliar, you can increase the vulcanization time and increase the vulcanization temperature. For products with more complex structures, pay special attention to the demolding method to improve the operation level of the demolding workers.

5. Reduce the frequency and amount of spray release agent, which can effectively prevent the release agent from contaminating the surface of the mold cavity, resulting in difficult mold sticking.
6. Use a certain amount of release agent.

The statistical theory of rubber elasticity discusses the generality of all rubbers. The ideal molecule that has no interaction force between molecules and the molecular chain can rotate freely is the research object. The elasticity of rubber is completely generated by the change in the conformation of the crimped molecule, between stress and deformation. It is in equilibrium and has nothing to do with the chemical composition of rubber. However, the real rubber is not like this, the molecules are attractive, and the size of the attraction depends on the chemical composition and structure of the rubber. The interaction between molecules will hinder the movement of the molecular chain, which manifests as viscosity or viscosity, so that the stress and deformation are often in an imbalanced state. One part of the force acting on the rubber molecules is used to overcome the viscous resistance between the molecules, and the other part deforms the molecular chains. These two constitute the viscoelastic properties of rubber. Elasticity and viscosity are combined by many materials, but high viscosity and high elasticity are unique to rubber. The viscoelastic properties of rubber processing are discussed in Chapter 6. This chapter focuses on stress relaxation, creep, hysteresis loss, recovery and permanent deformation, and dynamic mechanical properties of rubber after being stressed, with emphasis on the effects of time and temperature.

1. Stress relaxation

1. The meaning of stress relaxation

At a constant temperature, the rubber is stretched to a certain length. As time goes by, the stress to maintain this length will gradually decrease. This phenomenon is called stress relaxation. In other words, under constant temperature and constant deformation, stress is a function of time.

The reason for the stress relaxation phenomenon is that the viscosity of the rubber is very large, and the instantaneous time when the external force acts on it cannot be uniformly distributed, and some chain segments may not be affected by the external force. Due to the uneven force distribution, the internal stress is large, and the molecules are in a state of tension. Then, the molecular chain moves and rearranges, and after a certain period of time, the internal stress can be eliminated and the equilibrium state can be reached. At this time, the stress also drops to the equilibrium value. Therefore, stress relaxation is the process of eliminating the stickiness hindrance. But for raw rubber, although there is entanglement between molecular chains, it is not a permanent horizontal bond after all. The molecules will gradually produce relative displacement between the chains to release the entanglement, and the stress will eventually relax to zero. Figure 5-20 shows the stress relaxation process of the vulcanized rubber molecular chain. If it is raw rubber, there will eventually be plastic flow, and the stress will be reduced to zero without equilibrium stress.

2. Simple stress relaxation model-Maxwall model

The use of simple models can help understand the phenomenon of stress relaxation. The earliest is the Markov model. As shown in Figure 5-21. This model consists of a spring and a piston (sticky pot) placed in a viscous liquid in series. The spring represents the curled molecular chain, and the viscous pot represents the attraction between molecules. When an external force acts on the model, the spring opens first, which means that the ideal rubber molecular chain is immediately deformed after the force is applied. The force on the spring is immediately transmitted to the piston, but the movement of the piston is hindered by the surrounding viscous liquid, and it takes a while to move. Therefore, at the moment of force application, all the deformation is reflected in the spring. With the extension of the force application time, the viscous pot moves, the elongation of the spring gradually decreases, and the force that maintains the constant deformation of the model also decreases.

In the process of work, we will more or less encounter some problems. For example, today's conveyor belt manufacturers and everyone are talking about the correct way to install the conveyor belt.

In fact, when the conveyor belt manufacturer installs the conveyor belt, it only needs to correctly operate the following seven processes, and there is no problem.

①Put a rolling and flexible shaft on the conveyor belt take-up core, and set the belt roll up. Before putting it on the shelf, be careful not to reverse the direction of the upper and lower rubber covers.

②In the workplace where it is not suitable to be put on the shelf, the conveyor belt can be guided away, and the conveyor belt at the fold should have a large radius of curvature to avoid damage to the conveyor belt. The fold should prevent heavy objects from being placed on the conveyor belt.

③If it is to replace the conveyor belt, the new belt can be connected with the old belt, and the unloading can be carried out together with the new conveyor belt of the device.

④For horizontal conveyors, old conveyors can be blocked at any point. For conveyors working in an oblique direction, the blocking point must be selected to avoid losing control due to its own weight.

⑤After the conveyor has set the position of the new belt, fix one end of the tape with a clamp, and then connect it with the rope that goes around the roller and the pulley, and the conveyor belt is balanced on the conveyor by the traction device. When pulling, Avoid kneading the conveyor belt and the frame.

⑥Fix one end of the conveyor belt on the conveyor frame with a clamp, and the other end is tightened by a pulley until the conveyor belt does not sag significantly on the return roller.

⑦Fix the tensioning device 100~150mm away from the starting point.