| CPC B22C 9/02 (2013.01) [B33Y 10/00 (2014.12); B33Y 30/00 (2014.12); B33Y 80/00 (2014.12)] | 2 Claims |
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1. An ultrasonic-assisted permeation and homogenization molding method for frozen printing liquid drops, using an ultrasonic-assisted permeation and homogenization molding device for frozen printing liquid drops, comprising an array nozzle, a sand paving device, an ultrasonic generator, a transducer, an amplitude-change pole and a low-temperature molding chamber, wherein the array nozzle is located on a two-dimensional motion system and configured for spraying a pure water solution as required to solidify a molding sand; the sand paving device is located above the low-temperature molding chamber and configured for paving the molding sand; the ultrasonic generator is located outside the low-temperature molding chamber and connected with a power supply, and the transducer is mounted on a side of a frozen sand mold printing device and connected with the low-temperature molding chamber by means of the amplitude-change pole, the molding method comprising the following steps:
step S1: selecting an appropriate molding sand according to characteristics of a casting, stirring printed sand mold materials with liquid nitrogen or dry ice, and cooling a premixed molding sand to a temperature of −40° C. to 0° C.;
step S2: turning on the ultrasonic generator, converting alternating current into an ultrasonic frequency electric oscillation signal, converting the ultrasonic frequency electric oscillation signal into an ultrasonic frequency mechanical vibration by the transducer, amplifying an amplitude of the ultrasonic frequency mechanical vibration by the amplitude-change pole connected with the low-temperature molding chamber, and transmitting the ultrasonic frequency mechanical vibration to a worktable;
step S3: paving a layer of frozen pre-mixed molding sand by the sand paving device in a low-temperature molding environment, and adjusting a frequency of the ultrasonic generator so that pre-paved molding sand particles are homogenized and distributed under ultrasonic vibration; and
step S4: driving the array nozzle by a control system to spray a pure water binder as required according to cross-section information of a current layer of a sand mold, wherein liquid drops are sprayed to a surface of the premixed molding sand and permeate to a bottom of a pre-cooled molding sand under an assistance of ultrasonic waves for solidification and molding; and repeating steps S3 and S4 to complete a printing of the sand mold by means of layer-by-layer stacking;
wherein a thickness of a frozen molding sand paved once by the sand paving device is 0.4 mm to 0.5 mm, a volume of a single liquid drop sprayed by the array nozzle is 40 pL to 80 pL, and the liquid drops permeate to bottom molding sand particles and freeze to solidify the sand mold; the ultrasonic generator generates 20 KHz low-frequency ultrasonic waves, wherein the 20 KHz low-frequency ultrasonic waves have a permeation promotion effect due to mechanical action, heating effect, and cavitation effect of the 20 KHz low-frequency ultrasonic waves and the 20 KHz low-frequency ultrasonic waves are configured to improve a permeation rate of the liquid drops in a frozen molding sand; and when the ultrasonic transducer and the amplitude-change pole are fixed, a cross section with zero amplitude of the amplitude-change pole is connected with the low-temperature molding chamber to reduce a loss of ultrasonic vibration energy.
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