System and method for forming disk part by performing two-stage atomizing and spraying

[0019] The present invention will now be further described in conjunction with the embodiments and drawings:

[0020] The system of this embodiment includes a vacuum chamber 1 with an internal size of 2m high and a diameter of 1.2m, a crucible 2 with a height of 0.2m and a diameter of 0.18m, a heating coil 3, a gas cylinder 5, and a mechanical ejection plate 7 with a diameter of 0.3m. Through rod 8, catheter 9, high-pressure gas atomization nozzle 10, cooling device 11, and 0.8m diameter ring mold 12; among them, crucible 2, heating coil 3, stop rod 8, catheter 9 and atomization nozzle 10 Located in the upper part of the vacuum chamber 1, the crucible 2 is located in the center of the upper part of the vacuum tank 1, and is connected to the catheter 9 through the threaded through hole at the bottom, the stop rod 8 is connected to the catheter 9 and the bottom of the crucible 2 The threaded through hole is coaxial and can move up and down along its axis. The taper end is separated from or attached to the threaded through hole at the bottom of the crucible 2 to control the flow of molten metal; the periphery of the crucible 2 is provided with heating The coil 3 and the atomizing nozzle 10 surround the outside of the catheter 9 and are connected to the gas cylinder 5 placed outside the vacuum tank 1 through a pipeline; the mechanical throw-out plate 7 and the ring mold 12 are placed in the lower half of the vacuum chamber 1 In part, the mechanical ejector 7 is connected to the rotating mechanism through a rotating shaft, and can rotate at a high speed along its axis. The upper end is provided with a cooling device 11 for cooling the working surface of the ejected plate. The ring mold 12 is placed in the mechanical ejector. Outside of the disk 7, the center of the lower end is connected with the rotating mechanism through a rotating shaft, and has two degrees of freedom of rotating around the axis and moving up and down along the axis.

[0021] The cooling device 11 uses liquid nitrogen to cool the working surface of the mechanical ejection plate 7 to improve its working life.

[0022] The tangential direction of the air outlet of the atomizing nozzle 10 forms an angle of 30° with the vertical axis, and the shape of the air outlet of the atomizing nozzle 10 is Laval. The pressure of the atomizing gas is preferably 0.2 to 1.5Mpa.

[0023] The mechanical ejection plate 7 has a certain eccentricity with the rotation axis of the ring mold 12, and the eccentricity is related to the diameter of the formed part.

[0024] Taking the injection-molded Al-20wt% Si ring blank as an example, this system is used to illustrate the implementation of the invention. Hypereutectic Al-Si alloys have excellent comprehensive properties such as light weight, high strength, and good wear resistance, which are gradually being used in important parts of automobile engines, such as thin-walled cylinder liners and cylinder liners. Under normal casting conditions, the increase of Si content will cause the coarsening of the primary Si phase, which greatly reduces the processing and mechanical properties of the material; while the blanks produced by traditional injection molding methods have a large porosity and require subsequent densification procedures. The method provided by the present invention can effectively solve the above-mentioned problems, and its specific implementation manners are as follows:

[0025] (1) Put the mother alloy into the crucible 2, and evacuate the vacuum chamber 1 to less than 50 Pa;

[0026] (2) Start the heating device 3 to heat the metal to a molten state and make it superheat to 100°C. Open the stop rod 8 so that the molten metal flows down the catheter 9 and enters the high-pressure gas atomization zone;

[0027] (3) A high-pressure inert gas is used to atomize the molten metal flowing down from the catheter 9. After the gas atomization is completed, the droplets fly to the mechanical ejection plate 7 at a higher speed, and a first-stage atomization cone 4 is formed between the atomization nozzle 9 and the mechanical ejection plate 7, and the droplets gradually solidify during the flight ;

[0028] (4) The droplets in the first-stage atomization cone 4 hit the high-speed rotating mechanical ejector plate 7. The droplets are further refined under the combined action of the impact force and the centrifugal force, and fly to the annular mold 12 at high speed to form a second Level atomization cone 6, the droplets continue to solidify during flight, and the solid fraction of the droplets when reaching the annular receiving mold is 60% by controlling the distance from the nozzle 10 to the mechanical ejection plate 7;

[0029] (5) The semi-solid metal droplet hits the annular receiving mold 12 at high speed. The annular mold 12 moves downward in the axial direction while rotating at a high speed, receives the atomized droplets and solidifies and forms. Due to the high-speed rotation of the mold 12, the semi-solid droplets squeeze the cavities generated during the deposition process under the action of centrifugal force, and the porosity of the formed blank is small.

[0030] (6) Reshape the obtained deposited blank and remove the process margin to obtain the final part.