Start-up and operating procedures of continuous lead extrusion machine
Dec 11, 2020
1 The temperature that the following parts should reach before starting up:
1.1 Mould base 2RT1——295℃
2RT2——290℃
1.2 Extruded lead cylinder 2RT3——300～320℃ (Pure lead 310℃)
2RT4——320～330℃ (pure lead 330℃)
1.3 Lead pipe 2RT6, 2RT5——340～380℃
1.4 18t lead melting furnace and 10t purification and holding furnace——360～380℃
2 Check whether the water flow of the machine head cooling system is unblocked, so as to avoid heat damage to the mold seat sealing ring.
3 Check if the liquid level of the two lead furnaces reaches the specified value, otherwise it is not allowed to drive. The agitator of the two-lead furnace should operate normally, and the scum and impurities in the furnace should be removed at any time.
The lead valve between the second furnace can be opened after meeting the requirements.
4 Check whether the amount of oil and water in the lubricating oil and water tank reach the specified value, and check the temperature of the oil and water: Generally, the oil temperature should not exceed 60℃, the water temperature should not exceed 35℃, and the inlet water temperature of the heat exchanger should be 20-25℃. Check the water intake, whether the water after the filter is clean and whether it is blocked.
5 Increase the temperature of the lead pipe from the 10-ton purification and holding furnace to the main engine to 380°C 10 minutes before starting up, and then open the lead valve to allow the lead liquid to flow into the machine.
6 Turn on the external cooling water of the circulating soft water heat exchanger.
7 Turn on the main motor, the sequence is: fan motor for main motor → main motor → circulating soft water pump → ordinary cooling water pump. Because the lubricating oil circulating cooling pump is always in working condition, it is not listed here during normal driving; but when driving for the first time, this pump should be turned on half an hour earlier. At this time, the external cooling water of the oil heat exchanger should also be turned on to work. The water pressure of the softened water circulating pump should be adjusted to 0.07～0.1Mpa, and the water pressure of the ordinary cooling water pump should be adjusted to 0.07～0.1Mpa. At this time, if the circulating water pump is evacuated or the water pressure gauge pointer vibrates, check the water volume in the soft water tank. Or eliminate the fault in the pipeline system.
8 When the screw speed is 4.5 to 5 rpm, run for 3 to 5 minutes, and then slowly adjust the flow of the cooling water of the airframe to make the airframe temperature drop evenly. At this time, the heating power of the heating zone of the fuselage has been cut off, keeping 2RT3 at 190～200℃, and 2RT4 at 250～260℃. As the temperature of the fuselage drops gradually, the rotation speed of the main engine can be slowly adjusted to steadily increase the amount of lead output to reach the required amount.
9 Slowly adjust the main engine speed and body temperature of the continuous lead extrusion machine. Don't do it too quickly. You should closely monitor the water flow, temperature changes in each area of the body, and changes in the main motor current, and adjust them at any time. The general adjustment steps are:
At the beginning, the cooling water flow of zone 3 and zone 4 is 0.5-1kg/min, then the cooling water in zone 6 is turned on, and then the cooling water in zone 4 is turned on again. During this process, you must be especially careful to monitor the inspection points in the fuselage: the temperature in zone 5 will increase, and the current of the main motor will also increase, indicating that the lead liquid has entered the fuselage at this time. Re-open the cooling water in zone 3, if the current and extrusion volume increase, the main motor speed and cooling water flow can be gradually increased. The increase of the main motor speed can only increase or balance the current, but not decrease. At this time, the heat of the fuselage is in a balanced state, so the speed of the main motor and the cooling water flow can be increased steadily, and finally the required lead output can be reached. Such an adjustment process generally takes 10 to 15 minutes, but if the inlet temperature of the cooling water is too high and the body cooling pipe has scale that prevents heat conduction, the adjustment time should be extended.
The recommended operating temperature during normal production is:
2RT1295～300℃
2RT2290～295℃2RT3
210～270℃2RT4260～270℃
Lead pipe 340～360℃
Lead melting furnace 360～380℃
The above is the recommended temperature when extruding pure lead. However, due to the different grades and properties of various alloy lead when extruding lead alloy, the temperature of each zone is also slightly changed, generally:
At low speed and low extrusion volume, the body temperature 2RT3 and 2RT4 should be higher.
At high speed and high extrusion volume, the body temperature 2RT3 and 2RT4 should be lower.
10 Before the extrusion volume is stable, do not open the die cooling water. When opening the die, adjust the water temperature to 40～60℃. If necessary, use the nozzle of the cooling water tank to cool the lead pipe.
11 Operation sequence of changing mold:
11.1 2 to 5 minutes before the end of normal production, turn off the cooling water of the fuselage, turn on all the heating elements of the fuselage to raise the temperature of the fuselage to the starting temperature (2RT3-310℃, 2RT4-330℃). Extrude the empty tube continuously.
11.2 When the body temperature has risen to 310°C at the top and 330°C at the bottom, run for 15 minutes, turn off the main motor.
11.3 Take out the cooling water nozzle of the machine head, use the front hydraulic thrust device to loosen the adjusting ring, and take out the mold stop bolt.
11.4 Use a hydraulic device to eject the mold core and mold cover, adjust the required mold, then screw on the mold stop bolt, tighten the adjusting ring, and put in the cooling water nozzle.
11.5 The thickness of the lead pipe is adjusted by the front hydraulic thrust device and the adjustment handwheel: The handwheel turns counterclockwise, the lead layer is thick, and vice versa.
11.6 Adjust the coaxiality of the lead pipe with the help of four bolts at the head.
12 If the oil circuit is found to be blocked or too short during operation, it should be shut down immediately for maintenance.
13 The liquid level indicator of the lead furnace should be coated with high temperature molybdenum disulfide lubricant every day, and the high temperature difluidized molybdenum lubricant should be coated before each lead valve is activated.
14 When the pressure of the mold base increases abnormally, the piston is pushed out, and the safety disc bursts, the machine should be shut down immediately for inspection.
15 When starting up, check the instruments, parts, pipes, etc. in the underground pit frequently. At least three inspections should be performed per shift.
16 Pay attention to the sealing condition of the lead pipe connection when the heating is turned on. Once lead leakage is found, close the lead valve and cut off the heating power supply.
17 During the initial use, close the lead valve after each use. After one stage of use, the lead pipe connection no longer leaks lead, and the lead valve does not need to be closed.
18 When the temperature of the lead pipe is raised, the lead valve can be opened to avoid the leakage of the connection caused by thermal expansion.
19 The relationship between the mold core, the mold sleeve and the outer diameter of the extruded lead pipe:
a=b+(1～2)mm
c=a+(2.2～2.4)d
Where: a mold core inner diameter
b Cable or rubber tube outer diameter
C mold sleeve inner diameter
d Lead layer thickness
When squeezing the cable, the inner diameter of the lead sheath is 0.1～0.5mm smaller than the outer diameter of the cable.
When squeezing the rubber tube, the inner diameter of the lead sleeve is 1~2mm smaller than the outer diameter of the rubber tube.
