The pressure control of the hydraulic conveyor belt vulcanizing machine is the key to ensuring the quality of the vulcanization process, which is mainly achieved through the following several ways:
Adjustment based on the hydraulic system
Regulating the relief valve: The relief valve is a key component for controlling pressure in a hydraulic system. The opening pressure of the relief valve can be changed by adjusting the spring pressure of the relief valve. Rotate the adjustment knob of the relief valve clockwise. The spring pressure increases, the opening pressure of the relief valve rises, and the system pressure increases accordingly. Conversely, counterclockwise rotation reduces the system pressure.
Changing the displacement of the oil pump: For variable oil pumps, the pressure can be adjusted by changing the displacement of the oil pump. Increasing the displacement of the oil pump will cause the system pressure to rise when the system flow demand remains constant. Reducing the displacement will lower the pressure.
Adjustment based on the mechanical system
Adjusting the lead screw nut pair: In some mechanical transmission vulcanizing machines, the pressure can be changed by adjusting the lead screw nut pair. Rotate the lead screw to move the nut on it, thereby changing the distance between the press plate of the vulcanizing machine and the worktable, and thus adjusting the pressure. When it is necessary to increase the pressure, rotate the nut towards the workbench. Conversely, it rotates in the direction away from the workbench.
Replacing springs: Some vulcanizing machines use a spring pressurization method. The pressure can be adjusted by replacing springs of different stiffness. Springs with greater stiffness can provide greater pressure under the same compression amount, while springs with less stiffness provide less pressure.
Control mode
Manual control: The operator manually adjusts the pressure through the buttons or knobs on the operation panel based on experience and the requirements of the vulcanization process. During the vulcanization process, the operator needs to closely observe the pressure changes and make adjustments according to the actual situation.
Replacing springs: Some vulcanizing machines use a spring pressurization method. The pressure can be adjusted by replacing springs of different stiffness. Springs with greater stiffness can provide greater pressure under the same compression amount, while springs with less stiffness provide less pressure.
Control mode
Manual control: The operator manually adjusts the pressure through the buttons or knobs on the operation panel based on experience and the requirements of the vulcanization process. During the vulcanization process, the operator needs to closely observe the pressure changes and make adjustments according to the actual situation.
Electrical control
Pressure relay control: Pressure relays can convert pressure signals into electrical signals. In the vulcanizing machine system, the upper and lower limit values of the pressure relay are set. When the system pressure reaches the upper limit value, the pressure relay sends a signal to stop the oil pump motor or reduce the displacement of the oil pump, thereby stopping the pressure rise. When the pressure drops to the lower limit value, the pressure relay sends a signal to start the oil pump motor or increase the displacement of the oil pump, causing the pressure to rise again, thereby achieving automatic pressure control.
PLC control: The pressure of the vulcanizing machine is precisely controlled by using a programmable logic controller (PLC). The system pressure is detected in real time by the pressure sensor and the pressure signal is fed back to the PLC. The PLC outputs the control signal to the oil pump motor or hydraulic valve according to the preset pressure value and control algorithm, and automatically adjusts the pressure to achieve closed-loop control of the pressure.
Key points of pressure control
System pressure setting: The low-pressure pressure of the system is controlled by a low-pressure relief valve, mainly used to control the mold closing speed of the equipment. The low-pressure pressure can only be adjusted until the plunger rises faster, generally ranging from 0.2 to 0.5Mpa. The high-pressure pressure of the system is controlled by a high-pressure relief valve, which is mainly used to control the high-pressure pressure of the equipment. It can be set by adjusting the upper limit of the high-pressure relief valve and the electrical contact pressure gauge according to different processes, but the maximum high-pressure pressure must not exceed the rated pressure of the system (such as 16Mpa).
Oil supply and pressure control in the hydraulic system: The oil supply needs to ensure stable oil pressure and flow rate to meet the working requirements of the hydraulic cylinder. Pressure control can be achieved by adjusting the pressure valves in the hydraulic system to ensure the synchronous performance of the hydraulic cylinders.
Control mode
Manual control: The operator manually adjusts the pressure through the buttons or knobs on the operation panel based on experience and the requirements of the vulcanization process. During the vulcanization process, the operator needs to closely observe the pressure changes and make adjustments according to the actual situation.
Electrical control: Pressure relay control converts pressure signals into electrical signals. In the vulcanizing machine system, the upper and lower limit values of the pressure relay are set. When the system pressure reaches the upper limit value, the pressure relay sends a signal to stop the oil pump motor or reduce the displacement of the oil pump, thereby stopping the pressure rise. When the pressure drops to the lower limit value, the pressure relay sends a signal to start the oil pump motor or increase the displacement of the oil pump, causing the pressure to rise again, thereby achieving automatic pressure control.
Control by PLC: The pressure of the vulcanizing machine is precisely controlled by a programmable logic controller (PLC). The system pressure is detected in real time by the pressure sensor and the pressure signal is fed back to the PLC. The PLC outputs the control signal to the oil pump motor or hydraulic valve according to the preset pressure value and control algorithm, and automatically adjusts the pressure to achieve closed-loop control of the pressure. The computer can display pressure data in real time, draw pressure curves, and preset multiple pressure control schemes according to different product and process requirements. Operators can conveniently adjust the pressure and set control parameters through the computer interface. Meanwhile, the computer system can also store and analyze the pressure data, which is convenient for production management and quality traceability.
Combination of manual control and automatic control
Manual control: The operator manually adjusts the pressure through the buttons or knobs on the operation panel based on experience and the requirements of the vulcanization process. During the vulcanization process, the operator needs to closely observe the pressure changes and make adjustments according to the actual situation.
Pressure relay control: Pressure relays can convert pressure signals into electrical signals. In the vulcanizing machine system, the upper and lower limit values of the pressure relay are set. When the system pressure reaches the upper limit value, the pressure relay sends a signal to stop the oil pump motor or reduce the displacement of the oil pump, thereby stopping the pressure rise. When the pressure drops to the lower limit value, the pressure relay sends a signal to start the oil pump motor or increase the displacement of the oil pump, causing the pressure to rise again, thereby achieving automatic pressure control.
Synchronous control of the hydraulic system
The design and selection of hydraulic cylinders: Hydraulic cylinders are the actuating components in the hydraulic system of vulcanizing machines, and their design and selection directly affect the realization of synchronous control. In the hydraulic system of the vulcanizing machine, double-acting hydraulic cylinders are usually adopted, and synchronous control is achieved by controlling the oil inlet and outlet ports of the hydraulic cylinders. The design and selection of hydraulic cylinders need to take into account factors such as working load, speed requirements, and stroke length to ensure the synchronous performance of the hydraulic cylinders.
Closed-loop control: The position and speed of the hydraulic cylinder are monitored in real time through sensors, and the inlet and outlet ports of the hydraulic cylinder are adjusted through control valves to achieve synchronous control.
Oil supply and pressure control: Ensure stable oil pressure and flow rate by adjusting the pressure valves in the hydraulic system.
Control system design and commissioning: Design based on the working requirements of the vulcanizing machine and the characteristics of the hydraulic system, select appropriate controllers and sensors, and carry out commissioning and optimization.
Stress testing and verification
After adjusting the pressure of the hydraulic system, a pressure test is required to ensure that the system can operate normally and maintain the required working pressure. When conducting pressure tests, pressure gauges or other pressure monitoring devices can be used to monitor the working pressure of the hydraulic system.