2、 Our company's renovation plan and measures

The basic control logic of the modified loading oil station can be roughly summarized. After the roller lifting command is given, the grinding roller starts to lift quickly and can quickly leave the material layer and lift the roller into place within 30 seconds, reducing the material layer vibration caused by the slow roller lifting. When the roller is lifted into position, the induction limit switch is interlocked with the leak free electromagnetic ball valve to cut off the oil supply in the pipeline, thereby preventing the collision of the oil cylinder. At the same time, the leak free electromagnetic ball valve is also in a pressure maintaining state to keep the grinding roller in the upper limit position and wait for feeding. After receiving the instruction to drop the roller, the grinding roller falls and the speed of the falling roller is alleviated through an electromagnetic ball valve to prevent it from falling too quickly and avoid causing impact on the grinding disc. During the operation of the pressure roller, it can automatically increase or decrease pressure to maintain normal working conditions. When the mill suddenly trips, the quick release valve can be opened to quickly release the pressure in the rod chamber to 0MPa within 3 seconds, reducing the vibration during the mill trip and protecting the grinding disc and roller surface.

Therefore, the renovated loading oil station has the functions of fast roller lifting, upper limit position preventing cylinder collision, upper limit position maintaining, waiting for feeding, roller dropping, pressure maintaining/pressurizing/reducing during the grinding process, stopping grinding and quick unloading, self weight roller dropping, and manual roller dropping. The specific means, measures, and related features to achieve the above functions will be elaborated below.

The scope and content involved in this renovation include the renovation of the loading oil station, grinding roller lubrication oil station, as well as the electrical control cabinet renovation of the loading oil station and grinding roller lubrication, and the pipeline renovation from the oil station to the mill.

2.1 Renovation measures for loading oil stations

The renovation of the loading oil station includes dismantling the old oil station on the original site and installing and debugging the new oil station after the renovation. The supply, dismantling, and new installation and commissioning of the entire loading oil station are all carried out by Sichuan Hengzhuo Hydraulic.

2.1.1 Adopting dual oil pump cross drive, one pump controls the 1 # and 3 # oil cylinders, and the other pump controls the 2 # and 4 # oil cylinders. Two 110L/min oil pumps and four limit electromagnetic ball valves are used, with a working stroke of about 120mm (adjustable stroke). After modification, the roller lifting time is about 25 seconds, and the roller pressing time (from 0MPa to 5.5MPa) is about 30 seconds.

2.1.2 When one of the main oil supply pump systems is damaged and cannot work properly, it can be manually switched to the other pump to control the 4-roll mill to continue running, without affecting the normal and stable operation of the vertical mill.

2.1.3 The original limit is a mechanical limit, and it is easy to hit the hydraulic cylinder when lifting the roller into place. After the renovation, each oil cylinder is equipped with a roller lifting limit electromagnetic ball valve, which is interlocked with the mechanical limit signal. The roller lifting stroke can also be adjusted, and the interlocking control immediately stops oil supply after the roller is lifted in place. This not only maintains pressure after the roller is lifted, but also prevents collision with the hydraulic cylinder.

2.1.4 It has a manual differential function, which can balance the pressure of the upper and lower chambers of the hydraulic cylinder. In case of damage to the hydraulic cylinder, it can still be used for grinding. Please refer to the system schematic for details.

2.1.5 It has automatic pressurization and depressurization functions. In case of uneven material layers or large blocks, the hydraulic system can automatically pressurize or depressurize, improving the reliability and stability of the system. Please refer to the system schematic for details.

2.1.6 Add a manual pressure relief valve group. When maintenance is required, manual pressure relief can be carried out in advance to ensure safety. See system for details

 Our company's renovation plan and measures

The basic control logic of the modified loading oil station can be roughly summarized. After the roller lifting command is given, the grinding roller starts to lift quickly and can quickly leave the material layer and lift the roller into place within 30 seconds, reducing the material layer vibration caused by the slow roller lifting. When the roller is lifted into position, the induction limit switch is interlocked with the leak free electromagnetic ball valve to cut off the oil supply in the pipeline, thereby preventing the collision of the oil cylinder. At the same time, the leak free electromagnetic ball valve is also in a pressure maintaining state to keep the grinding roller in the upper limit position and wait for feeding. After receiving the instruction to drop the roller, the grinding roller falls and the speed of the falling roller is alleviated through an electromagnetic ball valve to prevent it from falling too quickly and avoid causing impact on the grinding disc. During the operation of the pressure roller, it can automatically increase or decrease pressure to maintain normal working conditions. When the mill suddenly trips, the quick release valve can be opened to quickly release the pressure in the rod chamber to 0MPa within 3 seconds, reducing the vibration during the mill trip and protecting the grinding disc and roller surface.

Therefore, the renovated loading oil station has the functions of fast roller lifting, upper limit position preventing cylinder collision, upper limit position maintaining, waiting for feeding, roller dropping, pressure maintaining/pressurizing/reducing during the grinding process, stopping grinding and quick unloading, self weight roller dropping, and manual roller dropping. The specific means, measures, and related features to achieve the above functions will be elaborated below.