Shuanghu Production Base, Daxin Town,
Jimo District, Qingdao City, Shandong Province, China
Wire rope core conveyor belt is made of many soft thin wire ropes separated by a certain distance, and bonded with rubber with good adhesion to the wire rope. Therefore, the steel cord conveyor belt has the characteristics of high strength, good impact resistance and bending fatigue resistance, small elongation and small thickness. Usually, the conveyor belt with the same number of steel wire cores should be selected for the replacement of conveyor belt. But now, in production, there are also conveyor belts with different number of steel wire cores gradually replacing the original conveyor belt. We take 48 and 79 steel cord conveyor belts as examples to analyze the vulcanization connection of different number of steel cord conveyor belts.
1 vulcanization bonding process < br />.
Vulcanization connection is to use the bonding force between rubber and core to bond the core of two conveyor belts together. When vulcanizing, the rubber on the two ends of the wire rope cores is stripped off, the two ends of the wire rope are dislocated and overlapped, and the rubber used for the connection is placed at the overlap position. Under certain pressure, temperature and time, the raw rubber lacking elasticity and strength is turned into ripe rubber with high elasticity and high bonding strength, and the cores of the two conveyor belts are joined together. The length of each conveyor belt is usually 100m. When using, several conveyor belts are selected according to the distance of conveyor, and vulcanized connection is adopted between each two conveyor belts. The strength of vulcanized joints can reach 85% to 90% or higher of the strength of the conveyor belt itself. Generally speaking, when the same number of steel cord conveyor belts are vulcanized, it is easy to divide the interface steel ropes into groups according to their length, middle and short, and overlap them in different grades according to their length, middle and short. However, it is very difficult to divide different numbers of steel cord conveyor belts when vulcanizing. When dividing, it is necessary to consider whether the length, middle and short overlap of each group of steel ropes is reasonable, and whether the number of groups of the whole interface is uniform, otherwise the service life of the interface will be affected.
2 vulcanization process < br />.
2.1 Selection of vulcanization sites
Vulcanizer is usually installed in the chamber near the tail of conveyor. Conveyor belt vulcanization should ensure that the chamber has good ventilation, no water, no coal dust, otherwise it will affect the quality of vulcanization interface. If the sulphide chamber is leached by water, anti-leaching measures should be taken; good ventilation can make the rubber and wire rope dry quickly after wiping, which can save time. But if the air volume is too large, it will be counterproductive, will blow a lot of coal dust, resulting in interface pollution, so the air must be in front of the vulcanizer < br />.
Set up the windshield.
Selection of 2.2 Vulcanizer
The selection of vulcanizing machine is suitable for split electrothermal steam vulcanizing machine. The boiler and heating plate of this kind of vulcanizing machine are separated. The steam generated by the boiler is sent to the heating plate through the pipeline to raise its temperature, so that the heat distribution on the heating plate is uniform, the vulcanizing temperature of the belt can be controlled, and the pressure required for vulcanization can be controlled by setting a hydraulic station. Therefore, the high quality of vulcanized interface can be guaranteed.
2.3 Determine Exploitation Joints
The length of vulcanization interface was determined to be 17-mm. If it is a new conveyor belt, draw a horizontal line perpendicular to the center line of the belt with a square ruler at 1700mm from the end of the belt. This conveyor belt is a vulcanized joint. If it is a conveyor belt in use, first select the position of the interface to be vulcanized, stop the interface at the vulcanizer, fix the conveyor belt at both ends of the interface, and cut the conveyor belt with a dolomite machine or a chopper. Draw a horizontal line perpendicular to the center line of the belt with a square ruler at a distance of 20-mm from the fracture. This section of the conveyor belt is the vulcanized joint. The length of vulcanized joint is slightly longer for the conveyor belt in use, because the wire rope at the joint is broken and corroded, so that the wire rope with broken wire and corroded section can be removed without re-peeling.
2.4 Exploitation and repair of joints
1) Exploiting connectors. From the side line of conveyor belt, the exploitation knife is used to exploit along the wire rope, until the cross line is drawn on the conveyor belt, the core of the wire rope is exposed, the rubber between the core of the rope is removed, and then the core of the wire rope is exploited in turn until all the wire rope cores are stripped out. Then the adhesive rubber on the core of the wire rope is removed and 3O is exploited from the root of the rope. The groove < br />
2) Repair joints. The two conveyor belt joints are laid flat on the heating plate under the vulcanizer, and grouped overlap is determined according to the bandwidth of conveyor belt, the number of steel wire cores and the diameter of the rope. The length of the joint core cuts the steel wire rope. Grinding conveyor belt groove with grinding wheel machine, both sides of groove should be grinded. Clean the core of each wire rope and the groove after polishing with a sponge dipped in 120 gasoline. This process is carried out at least three times.
Preparation of 2.5 vulcanizate
Prepare the vulcanizing compound in advance, check the quality of the compound, and use it after no problem. Sponge the surface glue and core glue with 120 gasoline until the glue surface has a certain viscosity. Every wipe should wait until the last gasoline volatilization clean. Then the core glue is laid flat on the surface glue and compacted. There should be no air between the core glue and the surface glue. If there is air, it must be released.
2.6 vulcanized joint < br />
1) Pre-curing compound. Cut the prepared lower rubber according to the size, spread it flat on the lower heating board of the vulcanizer, and lay a layer of cellophane between the heating board and the rubber. Use a sponge to dip in 120 gasoline and wipe it. After the gasoline has been volatilized, paste it on the rubber. At the same time, the rubber covering the upper part should also be wiped with gasoline and coated with paste. This process is carried out at least twice.
2) Conveyor belt joint lapping. After the paste is dried, the conveyor belt is laid flat on the rubber. The two cross sections of the conveyor belt should ensure the distance of 17-mm and the coincidence of the two centerlines. The lapping scheme is lapped. Straighten the steel wire cores of the two conveyor belts one by one, and arrange them evenly and neatly.
3) Cover the upper rubber. After setting the core of the wire rope, brush the glue once. After the paste is dried, cover another piece of rubber and hammer it down to remove excess rubber. If there is air between the two compounds, it must be released. It can be at
Dig a few holes in the glue. Good curing machine edge plate. Lay a layer of cellophane over the interface compound.
4) vulcanization. Adjust the hydraulic system of vulcanizing press, operate manual reversing valve, press the heating plate on the conveyor belt interface, adjust the pressure of relief valve, make the hydraulic system in a pressure-holding state, at this time the conveyor belt interface can reach 2 MPa pressure. When the steam pressure rises to 0.2 MPa, the intake valve is switched on and a small amount of steam is heated up and down the heating plate. At this time, open the exhaust valve on the upper and lower heating plates, remove the cold air and water in the heating plates, and close < br />.
Close the exhaust valve. When the steam pressure reaches 0.35 MPa, the insulation time is calculated by blackout, and the steam temperature can reach 145 C at this time. When the pressure of the steam pressure gauge drops to 0.32 MPa, the power supply is heated, and when the pressure reaches 0.35 MPa, the power is cut off. This is repeated several times until the heat preservation is finished after 45 rains. Open the exhaust valve to reduce the steam pressure to zero. Manipulate the reversing valve to relieve the pressure of the hydraulic system, raise the heating plate, take out the conveyor belt, and sulfide it.
3 Main points of vulcanization operation < br />.
In order to ensure the quality of vulcanization of conveyor belt joints, the following points must be paid attention to:
(1) Check the product qualification certificate of the compound and check the validity period of the compound. (2) The paste should not be too thick, thin and uniform when it is applied to the surface and core glue. (3) The paste painted on the rubber must be dried before vulcanization. There is no air between the layers of the rubber, and the air chamber must be deflated. (4) The groove of the joint must be ground out. _Wire rope core should be drawn straight and swing neatly, and rubber attached to the core should be exploited and cleaned. _Control the amount of rubber, not too much or too little, in order to avoid joint extrusion deformation or rope leakage defects. _The drawing line should be perpendicular to the center line of the conveyor belt, and the error of the center line of the two belts should not exceed 5 mm when aligning the joints. _The pressure of the vulcanized joint, the temperature of the heating plate and the time of vulcanization should be ensured during the vulcanization process. _Sulfide sites should maintain good ventilation, no water, no coal dust and so on.
4 Concluding remarks
Through the analysis of vulcanization joining process, it can be seen that vulcanization joining process is the key to the vulcanization joining of different number of steel cord conveyor belts. Practice has proved that the strength of vulcanized joints of different numbers of steel cord conveyor belts can be guaranteed and the safety of production can be guaranteed as long as the technological process is improved.