There is a close relationship between vulcanization pressure and the strength of conveyor belts. Reasonable control of vulcanization pressure is crucial for ensuring the strength of conveyor belts. The following analysis will be conducted from several aspects, including the influence of vulcanization pressure on the bonding strength and tensile strength of conveyor belts, as well as the selection range of vulcanization pressure:
The influence of vulcanization pressure on the bonding strength of conveyor belts
An increase in vulcanization pressure will reduce the movement space of molecular chains, bind the molecular chains, and at the same time decrease the distance between each rubber molecule, increasing the probability of bonding between rubber molecules and between rubber molecules and the interface molecules of steel wire ropes, thereby enhancing the bonding strength of the conveyor belt. For example, under the conditions of an experimental pressure range of 8-11MPa, a vulcanization time of 25 minutes, and a vulcanization temperature of 160℃, the bonding strength increases significantly at 10MPa. When the pressure increases to 11MPa, the increase is relatively small, indicating that further increasing the vulcanization pressure at this time has a relatively small influence on the bonding strength between the rubber and the steel wire rope.
The influence of vulcanization pressure on the tensile strength of conveyor belts
With the gradual increase of vulcanization pressure, the tensile strength of the conveyor belt will show a stable growth trend. When the vulcanization pressure is too low, the air in the rubber compound is not easily discharged, and the fluidity of the rubber compound will also decline. The density of the rubber and its adhesion to the steel wire rope will not meet the requirements, thereby affecting the tensile strength of the conveyor belt.
The selection range of vulcanization pressure
The vulcanization pressure of different types of conveyor belts varies. Generally, the vulcanization methods for molded products mainly include flat plate molding, transfer molding and injection molding. The suitable vulcanization pressure range for soft molded products is 1.5-2.0MPa. The outer tires of automobiles are 2.0-2.5MPa, and some are as high as 3.0-4.5MPa. The drive belt is 0.9-1.6MPa; The conveyor belt is 1.5-2.5MPa. When the rubber hose (water-wrapped cloth) is vulcanized by direct steam pressure, the pressure is 0.3-0.5MPa. When rubber shoes are vulcanized under pressure with hot air or mixed air, the pressure is 0.3-0.4MPa. When the thin adhesive cloth is directly steam-vulcanized, it is 0.1-0.3MPa. When continuous vulcanization with hot air, infrared or far-infrared vulcanization is carried out, normal pressure is adopted. The pressurization methods include compression molding (water pressure, oil pressure), mechanical pressurization, compressed air pressurization and injection molding with an injection machine, etc.
Excessive vulcanization pressure will cause the rubber to deform during the vulcanization process and its performance to decline. If the vulcanization pressure is too low, the air in the rubber compound will not be easily discharged, the fluidity of the rubber compound will decline, and the density of the rubber and its adhesion to the steel wire rope will not meet the requirements. When vulcanizing the conveyor belt, the pressure should not be too low. Low pressure will cause the rubber inside the joint to not bond tightly with the steel wire rope and the rubber itself, and volatile substances such as air cannot be discharged, making the inside of the joint look like bread and affecting the quality of the joint.