Aluminum Alloy Gravity Casting Automatic Production Line Design
1. Casting basics
The aluminum ingot is heated and melted, the temperature of the aluminum liquid is controlled at 740~750 °C, poured into the mold, and cooled and formed.
The housing of common motorcycle engines is cast by gravity.
Figure 1 Engine block casting
Aluminum alloy casting mainly involves melting furnaces, holding furnaces, casting machines, molds, etc.
At present, the automatic production line of aluminum alloy casting is still a combination of man and machine, manually completing mold purging, brushing coating, putting filter screen, and taking parts, and the robot completes automatic casting of aluminum molten water.
2. Engine block casting process
Manual pick-up machine→ manual cleaning mold→ manual brushing of paint→ manual placement of filters→ manual appointment casting → machine person takes liquid from the insulation furnace→ robot pours aluminum water→ pouring spoon oxide scale purge
Follow-up process of aluminum alloy castings: cooling→ shock sand → cutting riser
3. Composition and layout of engine block casting production line
The automatic production line of aluminum alloy casting of engine block is composed of holding furnace, robot (including base, seventh shaft, pouring spoon), descaling device, safety protection device and electrical control system.
Figure 2 Floor plan of casting automation production line
Figure 3 Three-dimensional rendering of casting automation production line layout,
4. Casting cycle timing
The working cycle time of a single casting machine is 180s, and it takes 35s for the robot to complete the casting of one casting machine, so one robot can meet the casting of 5 casting machines.
Table 1 Robot cycle time table
No. | Robot action | Time(s) |
1 | The robot walks from the waiting position to the holding furnace to take the liquid | 3 |
2 | Robot dispensing | 6 |
3 | The robot walks to the casting machine wetter port | 10 |
4 | The robot pours molten aluminum into the mold | 6 |
5 | Robot walk to blow oxidation device | 3 |
6 | Pouring spoon blow oxide scale | 5 |
7 | The robot returns initial position | 2 |
Total | 35 |
Table 2 Gravity casting machine cycle time table
No. | Robot action | Time(s) |
1 | Casting machine mold open | 2 |
2 | Manual pickup | 5 |
3 | Manual purging | 5 |
4 | Manual brush paint | 10 |
5 | Manual filter | 5 |
6 | Robot casting | 6 |
7 | Casting machine mold close | 2 |
8 | Cooling | 145 |
Total | 180 |
Aluminum alloy casting cycle calculation description:
The production cycle of gravity casting machine is 120s~180s, and the robot is between 35s~40s, and generally 1 robot pours aluminum water for 4~5 gravity casting machines.
5. Detailed description of casting automation supporting equipment
5.1 Holding furnaces
Table 3 Specification and parameter table of holding furnace (for reference only)
No. | Item | Value |
1 | Molten aluminum holding capacity | 4000kg |
2 | Aluminum output flow | 1.0t/h |
3 | The height of the water inlet from the ground | About 500mm |
4 | The temperature of aluminum liquid | 700~720℃ |
5 | Temperature control accuracy | ±5℃ |
6 | The temperature difference between the molten aluminum at the water intake and the molten aluminum in the holding chamber (furnace) | ≤20℃ |
7 | Heating rate | 8~12℃/h |
8 | Temperature difference of aluminum liquid in water inlet and degassing chamber | ≤15℃ |
9 | Temperature of aluminum liquid in degassing chamber | 710~740℃ |
10 | Combustion and temperature control mode | Automatic ignition inverter speed regulation |
11 | Power supply | 3P 380V 50Hz |
12 | Electricity consumption | ≤2kw/h |
13 | burner power | Max 20×10000kcal/h |
14 | Use fuel | Natural gas (actual calorific value 8400kcal/Nm3, supply pressure 7~9kPa, flow rate 10~12Nm3/h) |
15 | Gas consumption | ≤10±1.0m3/h (heat preservation state, the temperature of adding molten aluminum needs to be ≥680°C) |
16 | Oxidation and burn loss in the furnace (trouble-free continuous work for more than 3h) | ≤0.8% (heat preservation state, except when adding molten aluminum) |
17 | Outer wall temperature of holding furnace | ≤Ambient temperature +35℃ |
5.2 Gravity casting machines
Gravity casting machine refers to the machine that realizes the opening, closing and taking of metal gravity casting.
Figure 4 Flip gravity casting machine
5.3 Robots
Casting robot needs to choose the protection level IP67 casting version of the robot, according to the 7th axis and the weight and size of the spoon to choose the appropriate robot, generally the seventh axis weight 70kg, aluminum water weight 30kg, usually can choose FANUC R-2000iC/165F robot.
5.4 7th axis and level probe
The seventh axis is used to rotate the pouring spoon, in order to reduce the influence of high-temperature aluminum water on the robot, the length of the seventh axis is usually more than 500mm.
Figure 5 Robot seventh axis and spoon
Figure 6 Robotic spoon
The liquid level probe is used to detect the height of the aluminum liquid level, using the principle of metal conductivity, when the probe is in contact with the aluminum water, the circuit is turned on, and the signal is sent out in place, and the robot begins to ask for the aluminum liquid.
In addition, more and more holding furnaces have their own liquid level detection sensors, using non-contact laser displacement sensors, with an accuracy of ± 3mm, and real-time detection of liquid level height.
5.5 Pouring spoon
The spoon is used to scoop aluminum water, divided into stainless steel material and ceramic material, stainless steel spoon is heavier, and the thermal insulation performance is not as good as ceramic spoon, but ceramic spoon is more expensive and fragile.
Figure 7 ceramic pouring spoon
5.6 Flake blowing device
The oxide scale on the surface of the spoon is blown off by compressed air, and the purge action is controlled by a solenoid valve, and the length of time can be modified on the touch screen.
The compressed air blowpipe can be directly fixed on the 7th axis, adjust the angle of the end of the blowpipe, align the oxide scale on the surface of the spoon, blow it off, or make a separate device for blowing the scale, several compressed air blowing pipes are arranged around the inside, the robot will put the spoon into the blowing scale device, and the compressed air will blow off the oxide scale on the surface of the spoon.
Figure 8 aluminum alloy oxide scale
6 Casting Lessons
The quality of the cast product is very susceptible to temperature, humidity, exhaust, gate and other factors, must carefully understand the casting process in advance, observe the manual operation mode, otherwise, there may be manual casting no problem, but replace the robot casting can not meet the requirements.
Determine the type of aluminum alloy insulation furnace, there are continuous furnace and independent holding furnace.
To determine the size of the furnace mouth, the length and width ≥ generally required to be 500mm.
Generally, the layout of multiple pouring machines around the robot is adopted, and it is not recommended that the robot walk on the ground rail, and the high-temperature aluminum liquid may drip on the ground rail, affecting the life and function of the ground rail.
The spoon adopts robot additional shaft control, and the transmission methods of additional shaft include bevel gear transmission, turbine worm transmission and chain transmission.
It is recommended to use hexagon screws for the fasteners of the connecting part of the spoon to avoid the residual liquid from blocking the hexagon groove on the nut cap, which will affect the screw removal.
The inside of the spoon should be smooth and transitional, and there should be no steps at the joint.
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