How to operate hot-press ?

Before starting:
 
Requirements before startup 
1. The pressure of heat conducting oil can meet the technological requirements and keep supply. 
2. Clean the upper and lower surfaces of the cushion plate and the surface of the hot-pressing plate.
3. The accumulator pressure is normal and the oil level of the tank is normal. 
4. The transmission parts are well lubricated, running normally and the electrical equipment is normal.
5. There is no air in the cylinder and the sealing ring is well sealed.
 
Prepare for startup 
1. Close the main switch of the power supply and start the low-pressure pump so that the accumulator can meet the required working pressure. 
2. Open the heat conducting oil valve, close the heat conducting oil bypass circulation valve, and heat the hot pressing plate to reach the process temperature. 
3. Activate each conveyor in the cushion circulation system. 
4. Adjust the time of the time controller and the position of the upper and lower limit pointer of the pressure gauge according to the process requirements (if the total pressure changes greatly, the pressure regulating mechanism of the unloading valve and the safety valve should also be adjusted).
 
Start-up and shutdown:
 
start up sequence 
1. Start the oil pump motor of the board loading machine and the plate feeding motor, and the slab will enter the board loading machine one after another. 
2. When the loader is full and the wet slab is loaded into the hot press once, the relevant motors of the hydraulic pump system are activated, the solenoid valve switches and the time controller switches are opened, the press is closed and the boost is started. 
3. When automatic operation is required, turn on the corresponding automatic control switches. 
4. Manual operation, according to the process requirements, boost, buck and hold the pressure, and open the buck valve at the end of the hot-pressing cycle. 
5. Start the unloader and unloader conveyor; 
6. When the unloader pulls out the cushion plate and the reconstituted board, it loads the slab again and starts the second hot pressing cycle.
 
Inspection and adjustment in operation 
1. Adjust the time of the time controller appropriately according to the thickness and quality of the reconstituted boards (notify the billet forming process to adjust the billet forming process if necessary). 
2. Check the pressure of heat conducting oil and the temperature of hot plate, whether there is oil leakage in pipeline, and pay attention to the speed of temperature rise of hot plate after closure.
 3. Check whether the boosting, holding and lowering pressures at all stages of pressurization meet the pressure and duration required by the process, and adjust the relevant institutions in time. 
4. Check whether the lifting and pulling stroke of the loader is appropriate and the operation is stable. 
5. Check whether the piston sealing ring and pipeline are leaking oil. 
6. Check the operation coordination of each transporter in the cushion circulation system.
 
Stop Procedure Running
 1. When the loading machine feeds the last batch of wet slabs into the hot press, stop the loading machine and the feeding conveyor. 
2. When the hot press unloads the last batch of plates, stop the oil pump motors and open the bypass circulation valve.
 3. When the unloader has finished unloading the plate, stop the unloader and the mattress conveyor and turn off the main switch of the power supply.
 
Lubrication requirements 
1. Rolling bearings are cleaned and changed every 6 months with No. 4 calcium-based grease. 
2. The guide plate and rail are coated with compound calcium-based grease once a week. 
3. The oil pump adopts No. 46 anti-wear hydraulic oil, which is cleaned and changed every six months (old oil can be filtered). 
4. Pulley chains and other parts are filled with No. 30 oil every 24 hours.
 
Pre-start requirements
 1. Check whether the screw is loose and tighten in time. 
2. Check the oil level of the accumulator, the oil level of each tank and the lubrication condition of each lubricating part.
 3. The temperature of hot-pressing plate meets the technological requirements. There is no leakage of heat conducting oil, normal nitrogen pressure of accumulator and no leakage. 
4. The surface of the hot press shall not be stained with wood bundles or other dirt.
 
Operating requirements 
1. The piston of press and loader lifts smoothly without shaking and creeping, and there is no oil leakage in piston seal ring when the maximum pressure is reached. 
2. All oil pumps should not have abnormal noise and vibration. The temperature of the pumps and oil should not exceed 65 C.
 3. The load and temperature rise of each motor shall not exceed the stipulations. 
4. The positioning switch of loader is sensitive.
 5. The opening and closing action of the unloader hook is correct and the reaction is sensitive. 
6. There is no oil leakage at the joint of heat conducting oil hose. 
7. The temperature of the hot press rises to the same temperature as that of the return oil of the heat conducting oil, and the inlet and return valves run normally. 
8. The unloading valve, solenoid valve and electrical components react correctly and sensitively when the pressure rises or falls automatically.
 
Regular maintenance 
1. Inspection of the whole machine every 6 months (according to assembly and commissioning requirements);
 2. The wear and corrosion of the piston surface of the large piston and loader, especially the section of the seal ring intended for the highest position;
 3. Whether the parts of the hot-pressing plate are identical when heating up (whether the internal heat conducting oil passage is blocked or not);
 4. Wear of the size of the sealing rings of all hydraulic systems and the wear of all valve cores, springs and valves;
 5. Wear of gears, pulleys and guideways;
 6. Wear and seal of internal parts of oil pumps;
 7. Horizontal position and basic condition of frame and frame.

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