The operation of a manual conveyor belt vulcanizing machine needs to be combined with the characteristics of the equipment and the requirements of the vulcanization process. Through standardized steps and detailed control, the vulcanization quality and operational safety can be guaranteed. The following elaborates on the key techniques and precautions in detail from three stages: pre-operation preparation, vulcanization process control, and post-operation treatment:
First, preparation skills before operation
Equipment inspection and commissioning
Mechanical structure inspection: Confirm that the frame of the vulcanizing machine is not deformed, the stroke of the hydraulic cylinder is smooth, and the pressure handle is flexible without jamming. If oil leakage from the hydraulic cylinder or the pointer of the pressure gauge is found to be shaking, it needs to be repaired in advance.
Heating system test: Turn on the heating function and observe whether the reading of the temperature sensor matches the actual heating rate (usually it takes 10-15 minutes to heat up to 145℃). If the temperature fluctuation exceeds ±5℃, the temperature controller needs to be calibrated.
Flatness verification of vulcanized plates: Use a ruler to check the unevenness of the vulcanized plate surface. If the deviation exceeds 0.5mm, it needs to be sanded with sandpaper or the manufacturer should be contacted for repair.
Pretreatment of conveyor belts
Joint cutting: Use a special tool to cut the conveyor belt joint into a stepped shape. The width of each step should be greater than 1/3 of the belt width, and the edge should be ground to be free of burrs.
Cleaning and gluing: After wiping the surface of the joint with acetone, evenly apply two layers of rubber slurry, with a 10-minute interval between each layer, ensuring the thickness of the rubber layer is 0.2-0.3mm.
Joint alignment: After aligning the joints, fix them with fixtures, with the deviation controlled within ±1mm to prevent misalignment after vulcanization.
Safety protection configuration
Heat insulation measures: Lay asbestos cloth around the vulcanized plate to prevent the operators from being scalded by high temperatures.
Hydraulic system protection: Check whether the hydraulic pipelines are aged to prevent them from bursting and injuring people when pressurized.
Emergency equipment: Ensure that the operation area is equipped with fire extinguishers and be familiar with the location of the emergency pressure relief valve.
Second, control techniques for the vulcanization process
Key points of temperature control
Segmented heating method: First, heat at a rate of 5℃/min to 120℃, maintain a constant temperature for 5 minutes to pre-vulcanize the rubber, and then increase at a rate of 2℃/min to 145℃ to reduce the formation of bubbles.
Temperature uniformity maintenance: During the vulcanization process, measure the temperature at the four corners of the vulcanized plate with an infrared thermometer every 5 minutes. If the temperature difference exceeds 3℃, adjust the power of the heating tube.
Over-temperature treatment: If the temperature exceeds 150℃, immediately cut off the power supply and turn on the cooling fan. Wait until the temperature drops to 140℃ before continuing the vulcanization.
Pressure application techniques
Stepwise pressurization method: The initial pressure is set at 1.0MPa, maintained for 2 minutes, then increased to 1.5MPa, and finally pressurized to 2.0MPa and kept constant. Graded pressurization can prevent rubber from being extruded.
Pressure compensation mechanism: During the vulcanization process, check the pressure gauge reading every 10 minutes. If the pressure drop exceeds 0.2MPa, manual pressure replenishment is required.
Pressure release timing: After vulcanization is completed, release the pressure slowly only when the temperature drops below 80℃ to prevent the joint from cracking due to thermal stress.
Time control strategy
Thickness compensation method: For every 1mm increase in the thickness of the conveyor belt, the vulcanization time is extended by 2 minutes. For example, the vulcanization time of an 8mm thick conveyor belt requires 24 minutes.
Environmental temperature correction: If the environmental temperature is below 10℃, the vulcanization time needs to be extended by 10%. It shortens by 5% when the temperature is above 30℃.
Vulcanization progress monitoring: The degree of vulcanization is judged by observing the flow state of the rubber at the edge of the joint. If the rubber completely fills the joint gap and the surface is smooth, vulcanization can be stopped.
Third, post-operation processing techniques
Quality inspection method
Visual inspection: The vulcanized joint should be free of bubbles and cracks, and the rubber at the edge should have a smooth transition with the conveyor belt body.
Thickness measurement: Use a vernier caliper to measure the thickness of the joint, and the deviation should be controlled within ±0.5mm.
Peel strength test: Use a tensile testing machine to test the peel strength of the joint, which should reach more than 90% of the strength of the conveyor belt body.
Key points of equipment maintenance
Cleaning of vulcanized plates: Use a copper brush to remove the residual rubber on the surface of the vulcanized plates to prevent adhesion during the next vulcanization.
Hydraulic system maintenance: Replace the hydraulic oil and clean the oil tank, and check whether the sealing rings of the hydraulic cylinder are aged.
Calibration of the temperature control system: Calibrate the sensor readings with a standard thermometer. If the error exceeds 2℃, adjustment is required.
Safety wrap-up work
Equipment power failure: Turn off the power and unplug the plug to avoid accidental startup.
Tool repositioning: After cleaning the fixtures, scrapers and other tools, store them in the designated locations.
On-site cleaning: Remove rubber debris and oil stains generated during the vulcanization process to keep the operation area clean and tidy.
Fourth, skills for dealing with common problems
Joint bulging treatment
If a bulge appears at the joint after vulcanization, a utility knife should be used to cut along the edge of the bulge, and the internal gas should be removed before re-vulcanization.
Preventive measures: Before applying pressure, compact the joint with a roller to ensure that the rubber adheres tightly to the fabric layer.
Inadequate vulcanization remediation
If the joint hardness is insufficient or it is prone to tearing, the vulcanization time should be extended by 10%-15%, and the pressure should be appropriately increased by 0.2-0.3MPa.
Avoid repeated vulcanization: The number of repeated vulcanizations for the same joint should not exceed two times; otherwise, the strength of the joint will be reduced.
Emergency handling of equipment failure
Heating failure: If the temperature cannot rise, check whether the heating tube is open-circuited. You can measure the resistance value with a multimeter (the normal value is approximately 50-100Ω).
Insufficient pressure: If the hydraulic system fails to reach the set pressure, check whether the cylinder sealing ring is leaking oil and replace the sealing parts if necessary.
The operation of manual conveyor belt vulcanizing machines must strictly follow the process specifications. Through precise control of temperature, pressure and time, combined with equipment maintenance and quality inspection, the quality of vulcanized joints can be significantly improved. Operators need to attend regular training to be familiar with the performance of the equipment and the vulcanization process, so as to avoid joint failure or equipment damage due to improper operation.