KR100717165B1 - Piezo driven mill - Google Patents

Abstract

The present invention relates to a piezo drive mill for producing ultra fine powder using the excitation characteristics of the piezo element.

The present invention can effectively increase the amount that can be produced per unit time by reducing the grinding time or by establishing a continuous process by effectively grinding the fine powder into ultra fine powder by using a mechanical grinding method that impacts the high frequency of the piezo element. By selecting the impact part properly, it is possible to manufacture ultra-fine powder containing very little impurities, and it is easy to control the temperature of the impact part, thereby providing a piezo drive mill suitable for pulverizing temperature sensitive materials.

The piezoelectric drive mill provided by the present invention comprises a piezoelectric element driving actuator for crushing a product, the piezoelectric element driving actuator side and a circulation line, and a supply / circulation part for supplying and circulating the product, and the piezoelectric element of the piezoelectric element driving actuator It is composed of an electric control unit for exciting the element, and has the characteristic of pulverizing the product by using the vibration of the actuator by the excitation of the piezo element.

Ultra fine powder, driving mill, piezo element, piezo actuator, resonant frequency

Description

Piezo driven mill

1 is a schematic view showing the entire system of a piezo drive mill according to the present invention

Figure 2 is an exploded perspective view showing a piezo element drive actuator of the piezo drive mill according to the present invention

3A and 3B are sectional views showing an operating state of a piezo element driving actuator according to the present invention.

4a and 4b are photographs showing the before and after crushing of the zeolite particles

<Explanation of symbols for main parts of drawing>

10: piezo element driving actuator 11: supply / circulation part

12: electric control unit 13: cooling unit

14: entrance 15: exit

16: seat portion 17: body portion

18: housing 19: impact tip

20: spring 21: holder

22: rod 23: piezo element

24: Teflon housing 25: valve

26 tank 27 pump

28: electrode plate

The present invention relates to a piezo drive mill for producing ultrafine powders using the excitation properties of piezoelectric elements, and more particularly, to manufacturing ultrafine powders by mechanical grinding method using the impact of the piezoelectric elements, thereby producing them in a continuous process. The present invention relates to a piezo driven mill which is capable of being used, has a low impurity content in the grinding process, and is applicable to a temperature sensitive material.

Generally, powders are used in various industrial fields, for example, ceramics, semiconductors, cosmetics, pigments, dyes, paints, foods, pharmaceuticals, plastics, and various resins.

Particularly, in the case of ultra fine powder (1 μm to 1 nm), as the particle size decreases, the volume characteristic decreases and the surface characteristic becomes more prominent, resulting in a variety of new physical properties.

The apparatus currently commercialized as a conventional ultra fine powder production apparatus by mechanical grinding includes an agitator bead mill, a high energy planetary ball mill, and the like.

Looking at the principle of the mechanical grinding of the stirred bead mill, the grinding media (Beads) filled in the chamber is evenly dispersed in the chamber by a rotating rotor rotating at high speed, in the process the rotor and beads collide and dispersed Beads collide with each other frequently, and the collision causes the product filled in the chamber to be subjected to impact shear force between the collision materials.

This action causes the aggregated product or initial particles to disperse or pulverize.

In the case of the stirring bead mill, the size of the manufacturable particles depends on the size of the beads to be added, and beads having a size of 0.1 mm to 0.2 mm should be used to prepare the ultrafine powder.

However, when the beads are smaller in size, it is not easy to separate the beads from the fluid, the beads are expensive, and there are problems such as containing impurities due to the friction of small and numerous beads.

The high-energy satellite ball mill is currently being most used in the way that the ball impacts and crushes the product by controlling the rotational speed of the two shafts to put the ball and the product in the rotating and processing barrel.

However, in order to obtain ultra-fine powder, it is necessary to operate for a long time, so that the amount that can be produced per unit time is small, and there is a problem in that the temperature control is not easy in the case of a substance containing a temperature due to the wear of a ball and a barrel.

An object of the present invention is to effectively pulverize the fine powder into ultra fine powder by using a mechanical grinding method that impacts the high frequency of the piezo element, thereby increasing the amount that can be produced per unit time by shortening the grinding time or building a continuous process, etc. It is possible to produce an ultra fine powder having a very small amount of impurities, through proper selection of the impact part, and to provide a piezo drive mill suitable for pulverizing a temperature sensitive material due to easy temperature control of the impact part.

The present invention for achieving the above object comprises a piezo element drive actuator for pulverizing the product, the piezo element drive actuator side and the circulation line and supply / circulation for supply and circulation of the product, and the piezo element drive actuator It is composed of an electrical control unit for the excitation of the piezoelectric element, characterized in that it is possible to pulverize the product via the piezoelectric element actuator by using the vibration of the actuator by the excitation of the piezoelectric element.

The apparatus may further include a cooling unit configured to cool the heat generated in the piezoelectric element by using a cooling medium flowing through the line while forming a circulation line with the inside of the piezoelectric element actuator.

In addition, the cooling medium used in the cooling unit is characterized in that the insulating oil or air.

In addition, the piezo element driving actuator is characterized in that it is composed of a single type or a plurality of combinations arranged in series.

In addition, the piezo element driving actuator has an inlet and an outlet for the flow of the product, the body portion is provided with a sheet portion for crushing the product in the flow path, and closes the upper portion of the body portion and a predetermined space therein A holder for crushing the product by being installed in the space to be formed in the housing and the space formed by the body and the housing, having an impact tip contacting the seat, and receiving the elastic support of the spring, and being paired with the seat while vibrating up and down. It is characterized in that it comprises a supporting rod and a ceramic element mounted in a form coupled through the rod and is supplied with power from the electrical control unit.

In addition, the ceramic device is configured in such a way that a plurality of stacked on one rod in turn are stacked, each characterized in that the electrically connected in parallel.

In addition, the inner wall surface of the space formed by the body portion and the housing and the bottom portion through which the holder is characterized in that the Teflon housing is finished.

In addition, the supply / circulation unit is characterized in that it comprises a closed circulation line including a bypass line, a plurality of valves mounted on the line, and a tank and a pump for storing and providing circulation power of the product .

In addition, the electrical control unit controls the piezoelectric element driving actuator by matching the resonant frequency of the entire actuator with the resonant frequency of the actuator by a method of periodically supplying power to the piezoelectric element driving actuator. .

Piezo drive mill provided in the present invention comprises an electric control unit for having a piezo element, a piezo element drive actuator, a supply / circulation for supply and circulation of the material to be crushed, a cooling unit for cooling the piezo element drive actuator, etc. It is.

When the piezo drive mill supplies power at the same frequency as the resonant frequency of the actuator, the actuator portion (the portion including the piezo element, the rod, the holder, and the impact tip) vibrates, and the impact tip mounted at the end thereof is injured. The sheet portion is subjected to a high frequency impact and thus consists of a system for crushing particles passing between them.

Here, the electrical control unit for driving the piezo element is generally used, and a detailed description thereof will be omitted.

That is, a method of supplying a piezoelectric element to a power supply and the like may be adopted without particular limitation as long as it is a method commonly known in the art.

The electric control unit supplies power that is periodically changed to the same frequency as the resonant frequency of the actuator portion, and has the function of automatically finding the resonant frequency and operating in an optimum condition by measuring the amount of current consumed.

The piezo drive mill of the present invention can be used by attaching a plurality of actuator parts to one body part as needed, or by connecting them after making them into a modular form in which one actuator part is assigned to one body part. Can be.

The supply / circulation unit supplies a material to be pulverized, circulates with a pump for a predetermined time, and serves to classify the material.

The cooling unit is a device for absorbing heat generated from the piezoelectric element to circulate insulating oil or air to cool the actuator portion including the piezoelectric element.

An actuator portion is mounted inside the piezo element driving actuator, and an impact tip made of a material having high wear resistance is attached to the end of the actuator portion.

The part acting as a seat colliding with the impact tip is made of the same wear-resistant material.

One or more piezo ceramics, or piezoelectric elements, are connected in series to the actuator portion, and are electrically connected in parallel.

Electrode plates are located on both sides of each piezo element so that electricity can be applied to the piezo element.

The piezo element has a ring or polygonal shape with a central hole, and a rod penetrates subsequent holes and a nut at the end of the rod to apply stress to the piezo element.

Appropriate stress to the piezo element is a key factor in determining the resonant frequency and amplitude of the actuator part.

When a piezo element is operated, a lot of heat is generated, and in particular, when a plurality of piezo elements are used in series, cooling is required to absorb heat generated. In this case, the cooling method circulates insulating oil or air in an area to which an actuator part belongs. To cool the piezoelectric element.

The vibration of the actuator portion of the piezo drive mill of the present invention can be largely divided into two types.

One is the vibration of the piezo element itself and the vibration that occurs between the shock tip and the seat portion, and the spring pushing the actuator portion to the mass as a whole.

The self-vibration of the piezo element is caused by the expansion and contraction of the piezo ceramic, and is a mechanical vibration with a spring through the center of the piezo element.

This self-vibration of the piezo element causes vibration of the vibrometer with the actuator portion at full mass.

The maximum impact force can be obtained when the resonance frequency of the piezoelectric element and the resonance frequency of the entire actuator portion as the vibration system are well matched.

Hereinafter, a preferred embodiment of the piezo drive mill according to the present invention with reference to the accompanying drawings.

1 is a schematic view showing the entire system of a piezo drive mill according to the present invention.

As shown in FIG. 1, a form in which a plurality of piezo element driving actuators 10 are combined in series is shown.

The supply side / circulation portion 11, which constitutes one closed circulation line, is connected to the input side and the output side of the piezoelectric element driving actuator 10 to supply and circulate the product, and a plurality of valves 25 and a tank are formed on the line. 26 and a pump 27 are provided.

The valves 25 may perform functions such as interrupting, bypassing, and draining the product.

Accordingly, by driving the pump 27, the products in the tank 26 are crushed several times during the passage through the piezo element driving actuator 10 while circulating along the line with the fluid, and the predetermined cycle is repeated. The product can be ultra finely powdered.

In addition, the other side of the piezo element driving actuator 10 is connected to the cooling unit 13 consisting of one circulation line including a cooling tank 13a, a cooling pump 13b, and the like.

The cooling unit 13 circulates fluid or air to the piezoelectric element driving actuator 10, and thus effectively cools the heat generated by the excitation of the piezoelectric element using heat exchange with fluid or air. I can make it happen.

The electric control unit 12 for driving each piezo element includes a piezo driver 12a, a slide dax 12b, and the like.

The piezo driver 12a is a driving means for providing an piezoelectric element to the piezoelectric element driving actuator 10 by driving the piezoelectric element, and the sliced tooth 12b converts the input alternating current voltage into a desired size. As a means of providing power, it can be operated under optimum conditions by automatically finding the coincidence point between the resonant frequency of the piezo element and the resonant frequency of the actuator part by measuring the amount of current consumed and supplying the variable power periodically. Plays an important role in ensuring that

Figure 2 is an exploded perspective view showing a piezo element drive actuator of the piezo drive mill according to the present invention.

As shown in Fig. 2, the structure of the piezo element driving actuator 10 that performs the actual grinding operation for the product is shown here.

The piezo element driving actuator 10 is composed of a block-type body 17 and a cylindrical housing 18 finishing thereon, and the inner body of the body 17 and the housing 18 is formed. The piezo element 23 and the rod 22 for supporting it are mounted in the space part.

The body portion 17 has one inlet 14 and an outlet 15 opposite to the line side of the supply / circulation 11, respectively, and an extension passage between the inlet 14 and the outlet 15. The sheet portion 16 is mounted in the middle portion, so that the product passing therebetween may be crushed by the impact of the impact tip 19 and the impact tip 19 to be described later.

The housing 18 is fastened and assembled to the body portion 17 by a bolt or the like, and a nut support for supporting the spring is mounted at the upper center, and two holes are formed around the cooling part therethrough. (13) side and the circulation line can be configured.

In addition, a teflon housing 24 in the form of a cylindrical container constituting a wall surface and a bottom surface is mounted inside the space portion, and a rod 22 having a piezo element 23 along the central axis of the teflon housing 24. Can be arranged.

The rod 22 is supported in a vertically movable structure while penetrating the bottom of the Teflon housing 24 by using a holder 21 integrally assembled at the lower end thereof, and the upper end thereof is supported by the spring 20 to vertically flow. You will gain momentum.

At this time, it is preferable to secure airtightness and contactability through the mechanical seal or the like around the hole of the Teflon housing 24 through which the holder 21 penetrates.

In particular, at the end of the holder 21 extending to the seat portion 16 in the body portion 17, the impact tip 19 is mounted in a fastening structure, and the product is impacted by the impact that the seat portion 16 collides with. Can be crushed.

At this time, the impact tip 19 and the seat portion 16 is preferably applied to a material of high wear resistance, for example artificial diamond.

The piezoelectric element 23 that provides a substantial impact force is a kind of ceramic element that generates vibration while repeating expansion and contraction with power supply.

The ceramic elements 23 are configured in such a way that a plurality of ceramic elements 23 are sequentially stacked on one rod 22 and then integrally combined by a nut fastened to the rod 22.

An electrode plate 28 is disposed between each ceramic element 23 so that it can be supplied with power, and each is electrically connected in parallel.

Therefore, looking at the operating state of the piezo drive mill of the present invention configured as described above are as follows.

3A and 3B are sectional views showing an operating state of a piezo element driving actuator according to the present invention.

As shown in FIGS. 3A and 3B, the product proceeds continuously through the inlet 14 and the outlet 15 of the body 17, and the repetitive contraction of the powered piezo element 23 is performed. As the piezoelectric element 23 itself vibrates due to overswelling and at the same time, the vibration of the entire actuator portion is rapidly and rapidly made due to the influence of the excitation at this time.

The product passing between the impact tip 19 and the seat portion 16 may be pulverized by the vibration of the actuator and the self vibration of the ceramic element 23.

At this time, if the resonant frequency of the ceramic element 23 and the resonant frequency of the actuator part are well matched through the control of the electric control unit 12, the maximum impact force can be obtained, and thus the most effective grinding operation can be performed.

In the case of the finished product (for example, zeolite particles), it can be seen that the particles before grinding (FIG. 4A) are ground to ultrafine powder after grinding (FIG. 4B).

On the other hand, the resonant frequency of the piezo element and the resonant frequency of the actuator portion can be adjusted to match each other in consideration of the design variables and the initial stress, the piezo drive mill can be operated to set the resonant frequency as described above.

For example, a piezo element has its own frequency-impedance characteristic: the frequency with the lowest impedance is called fm (resonance) and the highest frequency is called fn (anti-resonance). It appears best.

When the piezoelectric element is applied to the actuator, the amplitude of the actuator portion can be increased by ensuring that the resonance frequency of the actuator portion is between the resonance frequency of the piezoelectric element and the resonance characteristic frequency of anti-resonance.

The resonance characteristic of the actuator part depends on the design variables and the initial stress. When the piezo element is applied to the actuator, the initial stress is applied by giving an appropriate torque to the fixing nut.

The resonance characteristic of the actuator portion varies depending on the initial stress applied to the piezo element, the elastic modulus of the rod passing through the center of the piezo element, the mass of the impact part, and the like.

After designing the proper resonant frequency in the piezo element driving actuator design, main design variables and initial stress are determined accordingly.

It is possible to adjust the resonance frequency of the vibration system between the entire actuator, the spring supporting it, and the impact sheet to match the resonance frequency of the piezoelectric element by adjusting the spring of the elastic modulus and the initial applied force applied to the spring.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art various modifications of the present invention without departing from the spirit and scope of the invention described in the claims below And modified.

The piezo drive mill of the present invention as described above provides the following effects.

First, the fine powder can be effectively pulverized by applying a shock at a high frequency of several kHz to several tens of kHz by the piezo element.

Second, when the impact part (tip / sheet) is made of a material such as artificial diamond having a high wear resistance, it is possible to prepare an ultra fine powder containing extremely little impurities during grinding.

Third, the impact portion is easy to cool, which is suitable for crushing temperature sensitive materials.

Fourth, when the piezo actuator and the housing are connected in series as modules, the grinding time can be easily shortened.

Claims (9)

delete Piezo element driving actuator 10 for crushing the product, the piezo element driving actuator 10 side and the circulation line and the supply / circulation 11 for the supply and circulation of the product, and the piezo element driving actuator In the piezoelectric drive mill, comprising an electric control unit 12 for exciting the piezoelectric element of (10), the product can be pulverized by using the vibration of the actuator caused by the excitation of the piezoelectric element. , Piezo drive mill further comprises a cooling unit 13 for cooling the heat generated in the piezo element using a cooling medium flowing through the line constituting a circulation line and the inside of the piezo element drive actuator 10 . The piezoelectric drive mill according to claim 2, wherein the cooling medium used in the cooling unit is insulating oil or air. Piezo element driving actuator 10 for crushing the product, the piezo element driving actuator 10 side and the circulation line and the supply / circulation 11 for the supply and circulation of the product, and the piezo element driving actuator In the piezoelectric drive mill, comprising an electric control unit 12 for exciting the piezoelectric element of (10), the product can be pulverized by using the vibration of the actuator caused by the excitation of the piezoelectric element. , The piezoelectric element driving actuator (10) is a piezoelectric drive mill, characterized in that composed of a plurality of combinations of one single type or connected in series. delete Piezo element driving actuator 10 for crushing the product, the piezo element driving actuator 10 side and the circulation line and the supply / circulation 11 for the supply and circulation of the product, and the piezo element driving actuator An electric control unit 12 for holding the piezo element of (10), and made to pulverize the product via the piezo element driving actuator by using the vibration of the actuator by the excitation of the piezo element, the piezo element The drive actuator 10 has an inlet 14 and an outlet 15 for the flow of the product, the body portion 17 is provided with a seat portion 16 is used for crushing the product in the flow path, and the body portion The housing 18 which closes the upper part of 17 and forms a predetermined space therein, and is installed in the space formed by the body 17 and the housing 18 and is in contact with the seat 16. The holder 21 and the rod 22 for supporting the holder 21 and crushing the product in pairs with the seat portion 16 while receiving the elastic support of the spring 20, while receiving the elastic support of the spring 20 and up and down oscillating; In the piezo drive mill is mounted in the form that is coupled through the rod 22 and comprises a ceramic element 23 is supplied with power from the electrical control unit 12, Piezo drive mill, characterized in that the ceramic element 23 is configured in such a way that a plurality of pieces are inserted one by one on the rod (22) in turn, and are electrically connected in parallel. Piezo element driving actuator 10 for crushing the product, the piezo element driving actuator 10 side and the circulation line and the supply / circulation 11 for the supply and circulation of the product, and the piezo element driving actuator An electric control unit 12 for holding the piezo element of (10), and made to pulverize the product via the piezo element driving actuator by using the vibration of the actuator by the excitation of the piezo element, the piezo element The drive actuator 10 has an inlet 14 and an outlet 15 for the flow of the product, the body portion 17 is provided with a seat portion 16 is used for crushing the product in the flow path, and the body portion The housing 18 which closes the upper part of 17 and forms a predetermined space therein, and is installed in the space formed by the body 17 and the housing 18 and is in contact with the seat 16. The holder 21 and the rod 22 for supporting the holder 21 and crushing the product in pairs with the seat portion 16 while receiving the elastic support of the spring 20, while receiving the elastic support of the spring 20 and up and down oscillating; In the piezo drive mill is mounted in the form that is coupled through the rod 22 and comprises a ceramic element 23 is supplied with power from the electrical control unit 12, Piezo drive mill, characterized in that the inner wall surface of the space formed by the body portion 17 and the housing 18 and the bottom portion through which the holder 21 passes through the Teflon housing (24). Piezo element driving actuator 10 for crushing the product, the piezo element driving actuator 10 side and the circulation line and the supply / circulation 11 for the supply and circulation of the product, and the piezo element driving actuator In the piezoelectric drive mill, comprising an electric control unit 12 for exciting the piezoelectric element of (10), the product can be pulverized by using the vibration of the actuator caused by the excitation of the piezoelectric element. , The supply / circulation unit 11 includes one closed circulation line including a bypass line, a plurality of valves 25 mounted on the line, a tank 26 and a pump for storing and providing circulation power of the product. 27) Piezo drive mill, characterized in that it comprises a. Piezo element driving actuator 10 for crushing the product, the piezo element driving actuator 10 side and the circulation line and the supply / circulation 11 for the supply and circulation of the product, and the piezo element driving actuator In the piezoelectric drive mill, comprising an electric control unit 12 for exciting the piezoelectric element of (10), the product can be pulverized by using the vibration of the actuator caused by the excitation of the piezoelectric element. , The electric control unit 12 supplies the piezo element driving actuator 10 to the piezo element driving actuator 10 by matching the resonant frequency of the actuator with the resonant frequency of the entire actuator. Piezo drive mill, characterized in that it is controlled.

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