What is Centrifugal Casting?
Centrifugal casting is a process that delivers castings of very high material soundness, and thus is the technology of choice for applications like jet engine compressor cases, petrochemical furnace tubes, many military products, and other high-reliability applications.
In the centrifugal casting process, molten metal is poured into a spinning die. The die can be spinning either on a vertical or horizontal axis depending on the configuration of the desired part. Ring and cylinder type shapes are cast vertically; tubular shapes are made with the horizontal centrifugal process. Either process may be used to produce multiple parts from a single casting. External structures and shaping can be cast in place to significantly reduce post-processing including machining or fabrication.
Because of the high g-forces applied to the molten metal in the spinning die, less dense material, including impurities, "floats" to the I.D. where it is subsequently removed by machining. Solidification is managed directionally under pressure, from the O.D. to the I.D., avoiding any mid-wall shrinkage, leaving a defect-free structure without cavities or gas pockets.
Two-station fully automatic centrifugal casting machine is composed of the two engines and a auxiliary engine. The two engines which are controlled by VFD are parallel layout. The two engines share auxiliary engine and pouring equipment. Auxiliary engine is controlled by servo and it includes cleaning, spraying, pouring, cooling, casting extraction devices .The whole process are controlled automatically.
The main engine's speed is adjustable and steady in the high speed.The Spraying process is very advanced of multistage velocity control. The key process parameters are real-time monitor and adjusted by automatic control system. So it can ensure the casting process parameters repetition and consistency. It eliminates the influence of artificial factors to the casting process parameters. So it ensures stable quality of the casings.
The main engines are obtained high-speed and stable as feature.The key factor affecting the product quality is whether the tube mold runs smooth and rotatory. Therefore, the smooth of the main engine is required to be very high. In the high-speed operation, the radial run-out of the tube mold is smaller, the wall thickness of the cylinder liner is more even, and the structure performance is more stable.
The main engine adopts four supporting wheel structure with the bearing base adopting cast iron material, so it has a good shock absorption capacity. The surfaces of the supporting wheels are processed with hardening and fine grinding processes. The main engine use ac frequency conversion motor and vector control converter. Riding wheel is rotated by V belt.So it ensures that the tube molds can be controlled with precise speed governing. Regenerative braking system ensures the fast stop of the tube molds. So the productivity can be improved.
Auxiliary engine has accurate locating control .Cleaning, spraying and tool for casting extraction mechanisms are compactly arranged on the mobile platforms. Through the position shift of the mobile platforms,the cleaning system,spraying system and extracting system will be in working positions of themselves.Servo positioning control is used in spraying system,extracting system and mobile platform.So they have accuracy control in the position and speed.It demands the strict requirements of processes and shorten the operating time,thus improving work efficiency.
Residual coatings in the inner wall of mold are cleaned rapidly.The cleaning bogie moves axial direction along the mold. On the cleaning bogie there is a spinning brush which clean the inner wall of mold.The brush can be changed to meet the different inner radius of mold. The cleaning device contains spraying nozzles and corresponding dust collector.
It has excellent spray coating quality.The function of tube mold's inner coating: 1 reduce the impact of metal liquid on the tube molds
2 reduce the peak temperature of the tube molds
3 effectively prolong the service life of the tube molds
4 increase the friction force between the tube molds and liquid metal
5 shorten the time of the pour-in metal liquid to achieve the tube rotation speed and also facilitate the casting pieces to release from the molds in tube drawing process.
The movement of the spray lance is controlled by servo.So it has the feature of smooth running and position adjustable.It ensures the uniformity of the coatings.The movement of the spray lance can be divided into three section.The speed and distance can be adjust in each section.Coordinate the rotation speed of the tube molds with the spraying pressure, the requirements of a variety of complex spraying processes can be satisfied.
Electric control system
Control system use PLC as the control core and use the man-machine interface as the monitoring system.It controls the whole process automatically and monitors the whole production process.Control system has the perfect protective measures, such as over-current protection, over-load protection, etc. The process parameters of the main engine and the auxiliary engine all can be adjusted and stored in the man-machine interface such as work positions and velocity. It meets the production process requirement of a variety of cylinder liner castings in a certain range.
Automatic pouring device is composed of pouring vehicle, pouring ladle, etc.
Pouring vehicle can serve two engines for pouring respectively.
The ladle's pouring speed can be adjusted.The automatic weighing device is used in pouring vehicle,which can ensure the consistency of the weight for each batch of cylinders. The weight of the molten iron in the ladle can be displayed on the big screen and the records can be printed.