General knowledge of zinc alloy die casting
1. Die casting is called die casting. Die casting is a process in which mold and mechanical equipment are used to rapidly fill the cavity under pressure, and then change from liquid to solid to form the required products.
2. Injection chamber can be divided into hot chamber die casting (zinc alloy commonly used) and cold chamber die casting (aluminum alloy commonly used). It can be divided into low pressure casting (such as automobile wheel housing) and pressure casting (such as our company's pressure casting), and can be divided into ordinary die-casting and vacuum die-casting from the exhaust mode.
3. What are die casting alloy materials and what are their characteristics?
The commonly used materials for die casting are: zinc alloy, aluminum alloy, magnesium alloy and copper alloy.
Its characteristics are as follows:
① The liquid has good fluidity;
② The melting point and freezing point are relatively fixed;
③ The shrinkage rate is small;
④ It has a certain high temperature strength;
⑤ It has good processability and corrosion resistance.
4. What are the main components of die casting aluminum alloy? What are the impurities?
The main components are: aluminum, silicon, copper, magnesium, manganese, zinc, etc.
Impurities include: iron, zinc, copper, tin, aluminum, sulfur, phosphorus, etc.
Different alloy grades have different requirements for main composition and impurity composition.
5. What are the main defects of die castings?
Generally speaking, there are under cast (unqualified material), crack, deformation, cold insulation, cold granulation, shrinkage porosity, porosity (sand hole), mechanical drawing, sticky die drawing, delamination, dislocation of mold, slag inclusion, surface cavitation, foaming, meat, meat, etc.
6. What is the temperature of aluminum alloy liquid suitable for die casting production?
Generally 650 ℃ ~ 720 ℃
7. What are the characteristics of die casting production?
(1) It has high production efficiency and can realize mechanized or automatic production;
(2) Good product quality: A. high dimensional accuracy, high surface finish; B. good mechanical properties; C. good interchangeability; D. clear outline, thin and complex casting wall, and high definition of patterns, patterns and characters;
(3) Economic effect: A. good economic index; B. low cost of die casting; C. It can be used as a combination of parts;
(4) The investment cost of die casting equipment and mould is high, which is not suitable for small batch production.)
8. What are the main components of die casting machine?
Die casting machine is mainly composed of closing mechanism, injection mechanism, ejection mechanism, power (hydraulic) system, control system, lubrication system, cooling system, etc.
9. What is the tonnage of die casting machine?
The tonnage of die casting machine is named after the closing force (locking force). For example, the clamping force of 180t die casting machine is 180 tons.
10. What is the function of the closing mechanism of die casting machine?
The function of the clamping mechanism is to install and fix the mold, and drive the moving parts of the die casting mold to open or close the mold.
11. What is the nominal pressure of the hydraulic system of die casting machine?
Generally 12 MPa (or 120 kg / cm2).
12. What is the role of the injection mechanism?
The injection mechanism is the key component in the die casting process. It makes the liquid metal from the injection chamber to inject into the mold cavity at a certain speed and pressure.
13. In normal production, what are the cycle action steps of injection punch?
The general procedure is: slow (from injection head to injection chamber gate)
Rapid (the injection head brings molten metal into the runner and sprue)
(2) Fast (from melting into gate to filling cavity)
Pressure (when the liquid metal fills the cavity, the injection cylinder pressure rises rapidly to a certain value, and the filling metal is compacted and maintained for a period of time) tracking (while opening the mold, the remaining material of the injection head and the gate sleeve continues to move forward for a certain distance)
Return (eject the head back to the initial state and complete a cycle)
14. What are the basic technical parameters of horizontal cold chamber die casting machine in China?
There are (1) clamping force (KN), (2) injection force (KN), (3) jacking force (KN), (4) lifting diameter (mm), (5) moving template stroke (mm), (6) mold thickness (mm), (7) injection chamber diameter (mm), (8) injection specific pressure (MPA), (9) casting area (cm2), (10) metal pouring amount (aluminum alloy) (kg), (11) System working pressure (MPA), (12) Coriolis column spacing (mm), (13) main motor power (kw).
15. What process parameters can be adjusted in die casting production?
(1) Die thickness, (2) closing speed, (3) opening speed, (4) closing time, (5) slow injection speed, (6) injection speed, (3) slow pressing stroke, (8) rapid stamping stroke, (9) injection pressure (specific pressure), (10) tracking stroke, (11) tracking delay, (12) ejection stroke, (13) ejection speed, (14) ejection delay, (15) Cycle time, (16) aluminum temperature, (17) mold temperature, etc.
16. What is the function of nitrogen bottle in die casting machine?
When rapid injection is required, a large amount of hydraulic oil is released from the accumulator to accelerate the injection head. When pressure is required, the accumulator immediately releases the pressure and pressurizes the injection head.
17. What is the function of lubrication system of die casting machine?
The lubrication system of die casting machine is a general independent system, which can automatically lubricate the sliding and rotating parts of the clamping mechanism within a certain time interval, which plays a key role in ensuring the normal operation and service life of the die casting machine.
18. What is the function of hydraulic system of die casting machine? What are the main components?
It is mainly composed of motor, oil pump, oil cylinder, various control valves and pipelines.
19. What is the function of the cooler?
It cools and protects the hydraulic system.
20. Why are injection rods and injection heads equipped with cooling water for cooling?
Because the cooling water installed in the injection head of the injection rod has the following functions:
(1) Heat is transferred from the injection rod to the hydraulic system;
(2) The results show that the wear of injector head is reduced at high temperature;
(3) Accelerate the cooling of the residual material, prevent the residual material from sticking to the injection head, and prevent the die from bursting due to insufficient cooling of the residual material. The process parameters are unstable due to deterioration;
(3) High oil temperature accelerates the aging of seal ring;
(4) If the oil temperature is too high, it is easy to cause deterioration, leakage and loss of hydraulic oil.
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