KR20010070880A - Manufacturing method of Metal Powder and facility of the same by Ultrasonic Atomizing Nozzle - Google Patents

Abstract

PURPOSE: A method and an apparatus for manufacturing metallic powder using an ultrasonic spray nozzle are provided which manufacture metallic powder stably, continuously and economically using a capillary wave generated from the nozzle. CONSTITUTION: In a method for manufacturing metallic powder, the method comprises the steps of vaporizing molten metal passing through the inside of an ultrasonic nozzle with the ultrasonic nozzle; and manufacturing metallic powder by solidifying the vaporized metallic drop. The apparatus comprises an injection unit injecting a certain amount of molten metal into the injection hole (9) of an ultrasonic nozzle through a molten metal guiding pipe made of ceramic materials including alumina in a melting furnace; an ultrasonic nozzle head (10) vaporizing the molten metal using vibration of capillary wave by transferring molten metal to the end part (12) of the nozzle through the channel (11) inside the ultrasonic nozzle; a length expanding rod (2) having a length of ultrasonic resonance as controlling a temperature gradient between the ultrasonic nozzle head and an ultrasonic transducer; an ultrasonic nozzle consisting of an ultrasonic nozzle head, an ultrasonic transducer supplying ultrasonic energy, and a length expanding rod, wherein there is a maximum amplitude of vibration at the end of the ultrasonic nozzle, and an amplifier system having an ultrasonic wave which manufactures metallic powder having a certain particle size and properties by feedback controlling ultrasonic energy supplied to the ultrasonic nozzle, thereby supplying a certain intensity of ultrasonic output to the ultrasonic nozzle.

Description

Manufacturing method and apparatus for manufacturing metal powder by ultrasonic spray nozzle {Manufacturing method of Metal Powder and facility of the same by Ultrasonic Atomizing Nozzle}

The present invention relates to a method and apparatus for manufacturing a metal powder using ultrasonic waves, and in particular, by controlling the capillary wave of ultrasonic waves, a metal powder having a uniform particle size and properties, which is less influenced by a difference in the amount of molten metal supply or a method. It's a technology that can make you productive.

It is well known that liquid is atomized when ultrasonic waves are irradiated to the liquid. As an example, ultrasonic humidifiers are widely used. It is also conceivable to apply such an atomization method to a molten metal to obtain a fine metal powder. Since molten metal has very different values of density, viscosity, and surface tension compared to water, spraying requires a variety of output sizes and output frequencies.These values affect the particle size, particle size distribution, and properties of fine powders. do.

The prior art in this field has a method of spraying by adding jets of air or liquid to a flowing molten metal, but it is relatively difficult to control the size and particle size distribution.

Ultrasonic metal powder manufacturing method, as shown in the experimental method of ULTRASONICS October in 1967, places a small amount of molten metal on an excited horn, and when ultrasonic energy is applied to it, it is atomized. The theory also proved that magnitude is inversely proportional to the (2/3) power of frequency. In addition, the method of placing a small amount of metal material on the surface of the ultrasonic wave and melting and micronizing it has been proved to be a method of obtaining spherical, fine particle size, and narrow particle size distribution. It did not apply.

Since then, many methods have been proposed to produce metal powder using ultrasonic waves. However, these studies have commonly applied molten metal from the outside of the vibrating body on the surface of the ultrasonic vibrating body which is in direct contact with the molten metal to make the metallic area by ultrasonic waves. It was limited to the method of metallization using the vibration of the ultrasonic vibrating body. This method has high variability and low reproducibility and has not been applied to mass production of metal powder. This is because when the flow of molten metal or the height change of the molten metal occurs in the excited horn, which is an ultrasonic vibrating body, the load fluctuation on the horn is severe and it is difficult to control the wave size finely.

Recently, the Japanese Patent Application Publication (S63-105907, Applicant, Japan Industrial Technology Institute, filed October 23, 1986) entitled "Method for manufacturing metal powder by ultrasonic wave and its manufacturing apparatus" has repeated the excitation horn in the molten metal. The method was designed to spray up and down by spraying on the surface of the horn with a certain amount of molten metal. The excitation part of the ultrasonic vibrator for metal powder production does not need to react with molten metal, and ceramics such as alumina, which are materials that can withstand high temperatures, may be used. Since it is generated and terminated, it is difficult to increase and concentrate ultrasonic power in molten metal at high temperature, and it is difficult to atomize a large amount of metal at once. In order to avoid this difficulty, the patent allows a small amount of molten metal to be repeatedly raised on the excitation surface and ultrasonically generated to micronize. However, such a method also has been difficult to produce a high quality continuous and practical metal powder having a uniform property and particle size. The reason is that it is practically difficult to repeatedly raise a certain amount of molten metal in the excitation horn, and it is not easy to precisely control the upper and lower positions of the atomization vibrating horn penetrating the smelting furnace. Since there is a risk of leakage and only a small amount of molten metal can be placed on the spray mixture, there is a limit on the yield. In addition, it is very difficult in this way to use a small diameter excitation horn which should be used in a relatively high frequency band of 40 kHz or more, which is used to make powder of small particle size. Since a small amount of metal was raised and melted in the vibrating unit once, it was difficult to replace the vibrating horn to control the excitation frequency of the ultrasonic wave, which has low productivity and influences the particle size.

The present invention has been made for the purpose of solving the conventional problems as described above, in order to achieve this purpose by using a capillary wave generated from the nozzle as shown in Figure 1 ultrasonic spray capable of producing a stable, continuous and economical metal powder An apparatus and method for producing metal powder using a nozzle (hereinafter referred to as an ultrasonic nozzle) are proposed.

Conventional methods for making metallic areas using ultrasonic waves supply the molten metal from the outside of the vibrating body on the surface of the ultrasonic vibrating body in direct contact with the molten metal to atomize the molten metal to make the molten metal. By forming a flow path and a nozzle for transporting the molten metal inside the sieve, the molten metal is supplied to the nozzle end of the ultrasonic vibrating body through the ultrasonic vibrating body to metallize by ultrasonic vibration there.

The flow path inside the ultrasonic vibrating body and the molten metal in the nozzle reach the nozzle end by capillary action, and a capillary wave whose size is controlled to the molten metal at the end of the nozzle is formed by ultrasonic vibration, and the amplitude of the capillary wave is precisely determined. It is a technique of producing metal powder by solidifying the metallic area by making molten metal and spraying molten metal to make the instability of the wave constant and controlling it.

The method of atomizing existing molten metal by mixing it in an ultrasonic mixture makes it difficult to control the ultrasonic wave for atomization by forming a fluidized bed in the mixed phase of the molten metal, or is supplied directly on the surface where the molten metal is atomized. The difficulty of controlling the ultrasonic wave size to atomize the molten metal is easily solved by the method of the present invention.

The physics of capillary waves using ultrasonic nozzles maintains a constant velocity while molten metal passes through a capillary tube consisting of a flow path and a nozzle even if there is some difference in supply of molten metal. Since it is under pressure distribution, it maintains a constant surface phenomenon, thereby securing an advantageous condition that enables precise wave control at the nozzle end. Therefore, the capillary wave is excited to the molten metal at the end of the nozzle which is always in a constant state, and the load center is controlled by the feedback control method of the electronic circuit to form a wave of a constant magnitude and frequency through the feedback control method of the electronic circuit. It is possible to produce a continuous and large amount of metal with good properties while having a narrow band of particle size distribution.

Actually, the high temperature of the molten metal has a great influence on the function of the piezoelectric element or magnetostrictive element, which is used to generate most of the ultrasonic waves, so that a device is needed to maintain the temperature of the piezoelectric element and the liquid phase of the molten metal. In the present invention, such an object can be achieved fairly easily by using the extension bar.

In addition, unlike the spraying metal powder manufacturing method using pneumatic or hydraulic pressure, the metal powder manufacturing method using the ultrasonic spray nozzle is very small in size and costs less. In addition, by easily changing the ultrasonic nozzle apparatus of various frequency bands, there is an advantage that the center size of the particles can be easily changed without changing other peripheral devices.

The method of obtaining metallic area by using ultrasonic energy by pouring into a horn with molten metal is not only difficult to control the flow of liquid metal, but also to increase the value of energy to atomize the metal. It has a practical deficiency in which ultrasonic energy of a size that can easily cause cavitation is applied. As a result of the ultrasonic cavitation, as a result, the distribution of the center size of the metal becomes wider and the mean center size is also changed a lot. The shape of the metal may not be spherical but bubbles may be formed in the metal. Precise micro-control of the wave is possible, which can be prevented properly.

The average size of the metal powder is proportional to the wavelength of the capillary wave, and the wavelength of the capillary wave is proportional to the power of the third divided by the square of the frequency with the surface tension of the molten metal divided by the density of the molten metal. Known. The present invention can easily adjust the size of the metal powder produced by using the ultrasonic nozzle by changing the ultrasonic frequency that is excited by replacing only this ultrasonic nozzle during metal powder production.

In addition, when the molten metal and the material of the ultrasonic nozzle cause a reaction, the ultrasonic nozzle head made of a material which does not react is simply replaced.

1 is an ultrasonic nozzle configuration of the present invention

※ Explanation of code for main part of drawing

1: handle of nozzle head 2: length extension bar

12 nozzle end 11 molten metal flow path in nozzle head

10: nozzle head 9: molten metal inlet

8 piezoelectric element 5 cooling chamber

4: Cooling fluid inlet 6: Cooling fluid outlet

3: front matching layer of ultrasonic transducer

The method and apparatus for manufacturing metal powder in the present invention include: a) an apparatus for injecting a predetermined amount of molten metal into an injection hole of an ultrasonic nozzle through a molten metal supply pipe made of a ceramic material such as alumina in a melting furnace; And an ultrasonic nozzle in the ultrasonic nozzle through which the injected molten metal is supplied to the distal end of the ultrasonic nozzle. The ultrasonic nozzle is configured to transfer the molten metal to the nozzle end through the passage to atomize the molten metal using capillary wave vibration. Head, c) an extension bar having a length of ultrasonic resonance while controlling the temperature gradient between the ultrasonic nozzle head and the ultrasonic transducer; d) an ultrasonic transducer for supplying ultrasonic nozzle head and ultrasonic energy; Ultrasonic nozzle with maximum vibration amplitude e) Ultrasonic nozzle Ultrasonic excitation amplifier system for feeding back the ultrasonic energy supplied to the bladdle to supply the ultrasonic power of a constant intensity to the ultrasonic nozzle to produce a metal powder having a certain particle size and properties.

According to the configuration of the ultrasonic nozzle for manufacturing metal powder, which is the core of the metal powder manufacturing apparatus, a transducer composed of a piezoelectric element or magnetostrictive element 8 which converts electrical energy into ultrasonic waves, and a rear layer and a front matching layer 13 of the element. There is. And an inlet for supplying molten metal at a cross section corresponding to a flow path 11 through which molten metal is supplied to the nozzle end, a capillary nozzle hole 12 with a different diameter as necessary, and a nodal line of axial ultrasonic vibration. There is an ultrasonic nozzle head 10 composed of 9 and nozzle head fixing part 1. In addition, while maintaining the resonance of the ultrasonic wave between the ultrasonic nozzle head and the transducer, the heat transfer path is lengthened to smooth the temperature gradient therebetween to reduce the thermal fatigue of the device and to extend the length to maintain the axial resonance of the ultrasonic nozzle. There are rods 2 and 13. This extension bar can be made into one if necessary. In order to cool the transducer, there is a cooling chamber 3, an inlet 4 and an outlet 6 of cooling water or air of the cooling chamber.

The ultrasonic nozzle composed of the transducer, the length bar, and the nozzle head has the longitudinal wave resonant structure of the axial ultrasonic wave so that the ultrasonic resonance in the axial direction can occur effectively. In particular, the flow path inlet 9 is located on the nodal line of the longitudinal ultrasonic wave. The nozzle hole 12 is configured to be positioned on the antinodal line in which the longitudinal ultrasonic vibration amplitude is maximum.

The present invention has succeeded in continuously mass production of ultrasonic metal powder by using a capillary wave to make a flow path to the end of the ultrasonic nozzle having a molten metal inside the excitation horn.

In addition, the diameter of the flow path, which is the main passage of the molten metal, is made larger than the hole diameter of the nozzle end portion, so that only a certain molten metal is supplied to the ultrasonic nozzle end to supply a certain amount of molten metal to a slight change in the supply amount from the outside of the molten metal. A practical device has been devised which can easily produce metal powder having a relatively large amount of homogeneous particle size and properties.

By spray nozzles for easy control of molten metal and control of capillary waves, a large amount of particles having a certain size and properties can be produced in a short time and can be used for atomization of various metals. In addition, by easily forming the spray nozzle or the horn with a ceramic or metal material that does not react with the molten metal, it is possible to prevent erosion of the nozzle or the horn by the metal.

In addition, by changing only the ultrasonic nozzle with a different resonant frequency and adjusting the output, it is possible to control the particle size, size distribution, shape, spray form in various ways, and the size of the device can be made much smaller than the existing metal powder manufacturing apparatus.

The movement speed of the molten molten metal to be sprayed is slowed to solidify the process to make a metal powder in a variety of ways.

Claims (6)

In the metal powder manufacturing method, Manufacturing apparatus and process for atomizing molten metal passing through the ultrasonic nozzle with this ultrasonic nozzle and solidifying the atomized metal to make metal powder It has an injection hole for injecting molten metal on the surface of the ultrasonic vibrating body, and the injection hole is located on the nodal line cross section of the longitudinal ultrasonic vibration amplitude of the ultrasonic nozzle device, and melts in itself from the injection hole to the end of the nozzle where the molten metal is atomized. Ultrasonic nozzle head for producing metal powder having a structure in which a metal flow path is formed Ultrasonic nozzles for the manufacture of metal powders, which consist of a nozzle head, an ultrasonic transducer, and a lengthwise softening rod to form capillary waves in the molten metal reaching the nozzle end to atomize the molten metal. Lengthening rod having length to delay the thermal fatigue of ultrasonic nozzle and maintain axial resonance of ultrasonic nozzle by lengthening the heat transfer path of supplied molten metal to slow temperature gradient between transducer and ultrasonic nozzle head. The diameter of the molten metal flow path in the ultrasonic nozzle head is made larger than the hole diameter of the nozzle end portion to accommodate a slight change in the external supply amount of the molten metal so that only a fixed molten metal is supplied to the ultrasonic nozzle end to control the supply of molten metal. Structure to make it easier Resonant frequency and electrical load fluctuation according to the load fluctuation of the ultrasonic nozzle device are sensed by the change of voltage or current supplied to the transducer to adjust the electric output, so that the constant ultrasonic amplitude is maintained at the end of the ultrasonic nozzle head, Devices characterized by electrical feedback control to be made