For many people engaged in industrial consumption, escort chain products are common. As an important symbol of automatic consumption, its role is irreplaceable.

1 transport chain

A chain is a flexible part connected by many chain links in the form of hinge pairs. The structural characteristics of the chain endow it with both high strength and sensitive bending in at least one direction.

Compared with belt drive and gear drive, the main characteristics of chain drive are:

1) Advantages:

It has no elastic sliding and slipping, can adhere to accurate and uniform transmission ratio, and has high transmission efficiency (closed chain transmission) η= 0.95～0.98)； The chain does not need to be very tight like the belt, so the axial force is small; High transmission power, strong overload ability; Can work well under low speed and heavy load; It can adapt to harsh environment, such as dusty, greasy, corrosive and high-strength places.

2) Defects:

The instantaneous chain speed and instantaneous transmission ratio are not constant, there is impact and noise in the work, and it is easy to jump teeth after wear. It is not suitable to be used in the transmission with large load change and rapid reverse.

2 working condition of high temperature transport chain

Under high temperature conditions, there are usually phenomena such as wear, corrosion, chain elongation, noise, chain oil dripping, etc.

2.1 common problems of transportation chain

(1) The chain is not smooth, resulting in frequent dry grinding of the chain and high noise;

(2) The chain shaft pin is seriously worn, and the chain stretches more than 1000mm;

(3) The chain is seriously rusted, and the rust slag falls onto the product surface, affecting the production and quality;

(4) At the initial stage of equipment operation, ordinary chain oil is used to make it smooth and show serious dripping phenomenon.

2.2 analysis on smoothness of high temperature chain in transportation

(1) Analysis of chain noise

The smooth point of the chain lies between the shaft sleeve, shaft pin and roller. The abnormal friction sound of the chain during practical operation also mainly comes from this part. This part requires chain oil to have:

① It has good permeability and can penetrate into the connecting part;

② Good extreme pressure and anti-wear performance to meet the smooth requirements between shaft sleeve, shaft pin and roller, otherwise abnormal chain wear will occur;

According to the above analysis, there is a problem of high noise during the operation of high-temperature chain transportation, which is closely related to the extreme pressure and anti-wear performance of smoothing agent.

(2) Analysis of chain stretching problem

The chain plate of the chain is made of cast iron, which will not stretch and other deformation conditions even under extreme load. The main reason for the stretching of the chain is the wear of the chain pin.

When the length of the transport chain reaches hundreds of meters, it receives a large load. At the same time, due to the poor smoothness of the bearing, its resistance increases sharply. If the chain does not have any effective smoothness, it will lead to serious wear between the chain pin and the shaft sleeve. According to similar working conditions, the service life of the chain is often less than two years when there is no smoothing or unqualified smoothing agent is selected.

(3) Analysis of chain corrosion

The escort chains for disposal before coating, electrophoresis and other parts operate under normal temperature (constant temperature about 45 ℃). However, it will be affected by acid-base solution and phosphating solution. At present, the chain is not smooth, the appearance of metal material is complete, and it is very easy to rust when exposed to acid-base gas / water mist. Therefore, chain oil products with good antirust performance are required to provide antirust maintenance for all parts of the chain while smoothing the chain.

(4) Analysis of chain oil dripping

2.3 smoothness of transport chain

2.3.1 chain smoothness

Dripping is a common problem, which can be reduced and prevented in the following ways:

Improve the viscosity grade of chain oil, the higher the viscosity, the better the adhesion;

Chain oil spraying installation capable of spraying high viscosity oil products shall be selected,

Ordinary fuel injection installation can only spray oil with viscosity below vg100;

The oil spray installation with oil mist spraying is selected to effectively prevent chain oil dripping;

Install an oil pan. If the above methods still cannot prevent dripping, it is recommended to install an oil pan.

2.3.2 requirements for smooth oil of transport chain

(1) The better oil can be firmly adsorbed on the inner surface of the chain without being thrown away by the centripetal force of the chain, or squeezed by the load and separated from the friction node.

(2) Better penetration can penetrate into each friction link of the chain link to form a border film and reduce wear.

(3) Good * * * * stability. When in contact with air during operation, it will not accelerate oxidation and form oxide.

2.3.3 smooth mode of transport chain

(1) Manual regular smoothing: use an oil pot or brush to inject oil once per shift. Suitable for low speed ν ≤ 4m / s transmission

(2) Smooth oil dripping: use an oil cup or oiler to drip 5 to 20 drops of smooth oil every minute through the oil pipe at the gap between the inner and outer chain plates of the loose edge chain. Apply to ν ≤ 10m / s transmission.

(3) Smooth oil bath: immerse the loose chain into the oil pan with an oil immersion depth of 6.12mm. Apply to ν= 12m / s transmission.

(4) Smooth Splash: in the sealed container, use the oil throwing pan to throw up the oil, flow along the shell to the oil collecting place, and then guide it to the chain. The linear speed of the oil slinger shall be > 3m / s.

(5) Pressure smoothing: when used ν For high-power transmission of ≥ 8m / s, special oil pump shall be used to radiate the oil to the meshing place of sprocket chain. The fuel injection nozzle is set at the meshing position of the chain. The number of fuel injection nozzles at each meshing position is (n + 1), and N is the number of chain rows

2.3.4 analysis of high temperature transportation chain oil and chain smooth grease

Today's high-temperature chain oil appears in different industries and categories due to its high-temperature resistance, smoothness and maintenance. In particular, today's chain oil can also smooth and maintain the chains in the equipment, so the application of high-temperature chain oil is still very common.

When it comes to the difference between high-temperature chain oil and chain smooth grease, of course, we should think about it before we can understand the detailed difference. First, in terms of adhesion, when the friction part is stationary, the smooth grease can adhere to the original shape and will not be automatically lost by gravity. When the friction part is in motion, the smooth grease will not be affected by centripetal force like high-temperature chain oil, showing oil leakage, but this is not the case with high-temperature chain oil, The adhesion is not very good

In addition, the operating temperature range of smooth grease in practice is wider than that of high-temperature chain oil. Due to its high-temperature resistance, high-temperature chain oil can be used under high-temperature conditions. However, today's smooth grease can be used not only at high temperature, but also at low temperature. Using smooth grease to stop smooth equipment is still very simple in structure, which can directly simplify the design and reduce the cost. However, high-temperature chain oil needs to stop smoothing in a closed system. The smooth equipment is also very complex in structure, so the cost will be relatively high.

When it comes to the difference between high-temperature chain oil and smooth grease, there are still many. For example, chain smooth grease can be directly applied to the metal surface to provide certain protection. Moreover, because the protective film is relatively thick, it can isolate various acid-base and other gases, but the protection ability of high-temperature chain oil is relatively poor.

2.4 transportation and installation of high temperature bearings

At present, high temperature bearings for transportation mainly include carriage bearings, track angle bearings and tension wheel bearings in the oven. In the process of high-temperature operation, the carriage bearing needs to withstand the high-temperature working condition of nearly 220 ℃ for a long time. At the same time, it needs to accept the weight of the workpiece due to the influence of acid-base solution and phosphating solution. Improper selection of bearing grease will increase the tendency of bearing oil sludge, carbon deposition and coking, aggravate bearing wear, damage the bearing frame, and even lead to bearing jamming and failure.

2.4.1 smooth requirements for transportation and installation of high temperature bearings

For transportation, bearings in high temperature zone have high requirements for smoothing agent. Generally speaking, the smoothing agent shall meet the following requirements:

(1) High extreme pressure and good wear resistance, can accept the weight of the workpiece;

(2) High adhesion ability, which can effectively adhere to the friction surface to form an effective oil film;

(3) Good high temperature stability, avoid high temperature loss of oil products, cause wear of friction pairs, and reduce waste of oil products and pollution to workpieces;

(4) It also needs excellent * * * * ability to inhibit the oxidative transformation of smooth oil and reduce the generation of carbon deposition and residue;

(5) For bearings working in polluted environment such as cold water, hot water, steam and sulfuric acid, it is required that the smooth grease should have good chemical stability and can resist complex media;

(6) Good compatibility with paint;