KR20180003653A - Magnetorgeological fluid functionally gradient foam unit and manufacturing the same - Google Patents

Abstract

The present invention relates to a magnetorheological and functionally graded foam unit, and a production method thereof. The magnetorheological and functionally graded foam unit is capable of absorbing energy for at least one of vibration or external shock and includes a polymeric mold capable of conducting self-reactions. The polymeric mold is composed of an elastically transformable polymeric substance, and a self-reactive substance capable of conducting the self-reactions by external magnetic field, and also includes as plurality of pores to improve variation rate of physical properties and absorption rate of energy. The diameter of the pores gradually gets smaller as going further to one direction, thereby favorably distributed to the polymeric mold.

Description

[0001] MAGNETORGEOLOGICAL FLUID FUNCTIONALLY GRADIENT FOAM UNIT AND MANUFACTURING THE SAME [0002]

The present invention relates to a magnetorheological function inclined foam unit and a manufacturing method thereof, and more particularly, to a magnetorheological function type inclined foam unit and a method of manufacturing the same. More particularly, the present invention relates to a magnetorheological function type inclined foam unit, A foam unit and a manufacturing method thereof.

Functionally Graded Materials (FGM) are created by the progressive transfer of two materials and the solidification process. That is, the functional tilting material is a material having a constant direction and a gradual change in the volume fraction or material properties of the material.

Functionally Graded Foam Materials in Functionally Graded Materials refers to materials whose porosity changes in size or density gradually. These functionally inclined foams have excellent impact resistance and high energy absorption characteristics. Particularly, the functionally inclined foam (functionally inclined foam unit) has excellent durability of elastic deformation by the compressive force and is utilized in various fields.

In general, the functionally inclined foam unit is made of metal. The functionally inclined foam unit made of metal has a high strength so that it is less damaged even by strong external impact and has a function as a functionally graded material. However, in the case of a functionally inclined foam unit made of a metal, there is a problem that the degree of change (change ratio) of physical properties by an external magnetic field is insignificant.

A conventional technique is disclosed in Korean Patent Laid-Open No. 10-1977-0010307 entitled " Method of manufacturing gradient functional ceramics ".

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems as described above, and it is an object of the present invention to provide a magnetorheological function inclined foam unit having a high rate of change of physical properties by an external magnetic field, And the like.

Another object of the present invention is to provide a method of manufacturing a magnetic gradient functional foam unit capable of realizing a functional tilting structure for a thermally polymerizable polymer.

The solution to the problem of the present invention is not limited to those mentioned above, and other solutions not mentioned can be clearly understood by those skilled in the art from the following description.

In order to accomplish the above object, the present invention provides a self-ramp function inclined foam unit including a polymer mold capable of absorbing energy for at least one of external impact or vibration and capable of self-reaction. The polymer mold is composed of a polymer material capable of elastically deforming and a magnetic reaction material capable of a magnetic reaction by an external magnetic field and includes a plurality of pores such that an energy absorption rate and a property change rate can be improved.

It is preferable that the pores are formed in such a shape that the diameter gradually decreases in one direction, so that the pores are distributed in the polymer template.

According to another aspect of the present invention, there is provided a method of manufacturing a self-rheometric functionally inclined foam unit, the method comprising: forming a polymer mixture by mixing a polymer material capable of elastically deforming and a self-reactive material; Curing the polymer mixture to form a gel-state polymeric mold having an incremental difference in cross-linking degree; A foaming agent saturation step wherein a pressure is applied to the polymer mold in a pressure vessel containing a liquid foaming agent so that the foaming agent is saturated inside the polymer mold; Forming a plurality of pores in the polymer mold by causing the foaming agent to be phase-changed into a gaseous state inside the polymer mold by removing the pressure; And a curing step of curing the polymer mold having a plurality of pores formed thereon.

The step of forming the polymer mold may include a step of forming the polymer mixture into a forming mold, cooling the upper portion of the forming mold, and simultaneously heating the lower portion of the forming mold so that the degree of cross- .

The supersaturated state of the foaming agent may be maintained so that the pores may be distributed in the polymer mold in such a manner that the diameter decreases gradually in one direction in accordance with the gradual difference in the degree of crosslinking.

Preferably, the foaming agent saturation step maintains the supercritical state of the foaming agent by maintaining the pressure and temperature inside the pressure vessel until the pore forming step.

The foaming agent saturation step may maintain the internal temperature of the pressure vessel at a temperature lower than the curing temperature at which the polymer mixture is cured.

The self-rheometric function type inclined foam unit and method of manufacturing the same according to the present invention having the above-described structure are characterized in that a polymer mold is formed from a polymer material capable of elastically deforming and a magnetic reaction material capable of self-reaction, The rate of change of the physical property by the external magnetic field is high, and the absorption rate of energy for impact and vibration is excellent.

In addition, by adjusting the degree of saturation of the polymeric mold by mixing the polymeric material and the magnetically responsive material to form a polymeric mixture and gradually changing the curing temperature of the polymeric mixture for forming the polymeric mold, Structure can be realized.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a perspective view illustrating a magnetorheological function inclined foam unit according to an embodiment of the present invention;
FIG. 2 is a flow chart illustrating a method of manufacturing a self-rheostat function inclined foam unit according to an embodiment of the present invention. FIG.
FIG. 3 is a conceptual view illustrating a step of forming a polymer mold according to an embodiment of the present invention. FIG.
4 is a graph for explaining temperature conditions of an embodiment of the present invention;
5 is a graph for explaining pressure conditions of an embodiment of the present invention.

Hereinafter, a magnetorheological function inclined foam unit and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view illustrating a magnetorheological function gradient unit according to an embodiment of the present invention, FIG. 2 is a flowchart illustrating a method of manufacturing a magnetorheological function gradient unit according to an embodiment of the present invention, FIG. 3 is a conceptual diagram illustrating a polymer mold forming step of an embodiment of the present invention. FIG. 4 is a graph for explaining a temperature condition of an embodiment of the present invention, and FIG. 5 is a graph for explaining a pressure condition of an embodiment of the present invention FIG.

As shown in these drawings, the magnetorheological function inclined foam unit according to the present invention comprises a polymer mold 100 and pores 101. [

The polymer mold 100 is made of a polymer material capable of energy absorption for external shocks and vibrations, and a magnetic reaction material capable of a magnetic reaction. In the polymer mold 100, the polymer material may be made of a silicone rubber, which is a kind of elastomer, in order to increase the rigidity variation.

In the polymer mold 100, the magnetoresistive material may be made of a carbonyl iron powder (CIP), which is a magnetically responsive material. The polymer mold 100 preferably comprises a thermally polymerizable type elastically deformable polymer in which the polymer material and the magnetically responsive substance are mixed with each other. Meanwhile, the polymer mold 100 may be made of a thermoplastic polymer or a photopolymerizable polymer.

The present invention is characterized in that the polymer mold 100 is made of a thermally polymerizable type elastically deformable polymer so that the physical property of the material changes according to the strength and direction of the external magnetic field. Therefore, the present invention has an advantage of having excellent impact resistance and high energy absorption rate and having excellent durability against elastic deformation according to a compressive force.

The present invention having such advantages can be utilized as an active-adaptive tuned absorber, various sensors and actuators using characteristics sensitive to a magnetic field.

Referring to FIG. 1, the pores 101 formed in the polymer mold 100 enable the energy absorption rate and the property change rate of the polymer mold 100 to be improved. The pores 101 are distributed in the polymer mold 100 by decreasing the diameter gradually in one direction.

By virtue of such a structure of the pores 101, the property change characteristic of the magnetorheic elastomer can be effectively incorporated into the functional gradient type foam unit, and the range of energy absorption for impact and vibration of the functional gradient type unit can be expanded It has the advantage of being able to make it.

Therefore, when the present invention is utilized as a damper, it can absorb more energy and have an excellent restoring force as compared with a general functionally inclined foam unit. In addition, when the present invention is utilized as a sensor, the sensing object can be sensed more sensitively than a general functionally inclined foam unit.

Meanwhile, as shown in FIG. 2, the method for manufacturing a self-rheological functional foam unit according to an embodiment of the present invention includes forming a polymer mixture (S110) for forming a polymer mixture and curing the polymer mixture to form a gel (S120) of forming a polymeric template in a state of being formed.

In addition, a foaming agent saturation step (S130) for foaming the foaming agent in the polymer mold and a pore forming step (S140) for forming pores in the polymer template due to saturation of the foaming agent. And a curing step (S150) of curing the polymer mold having pores formed thereon.

The polymer mixture forming step (S110) is a step of forming a polymer mixture by mixing a polymer material capable of elastically deforming and a magnetoresistive material. In the polymer mixture forming step (S110), the polymer mixture is in the form of a magnetorheological polymer liquid.

In the step of forming the polymer mixture (S110), a silicone rubber (Silicone Rubber) is used as a polymer material and a carbonyl iron powder (CIP) is used as a magnetoresistive material. The polymer material and the magnetoresistive material may be mixed by a generally used mixing method.

The polymer template forming step (S120) is a step of curing the polymer mixture to form a gel-state polymer template having a gradual difference in cross-linking degree. The polymer template forming step (S120) may include an initial curing step, wherein a temperature gradient of the curing temperature is applied to the polymer mixture in a liquid state to form a degree of cross- linking.

Here, cross-linking means that the polymer chains are chemically connected to each other at arbitrary positions other than at the ends via a direct or several bonds. The degree of cross-linking means how far the cross-linking of the polymer material and the magnetically responsive material has occurred.

The polymer mold forming step S120 is a step in which the polymer mixture is accommodated in a molding mold 200 as shown in Fig. 3, then the upper part of the molding mold is cooled, and at the same time, So that the degree of cross-linking of the polymer template gradually changes.

In the polymer mold forming step (S120), the degree of cross-linking of the polymer mixture in the gel state is lower toward the upper part of the forming mold 200 where the cooler 300 is located. On the other hand, the degree of cross-linking of the polymer mixture in the gel state is higher toward the lower part of the forming mold 200 where the heater 400 is located (see FIG. 3).

Here, " simultaneous " means the same time, indicating that cooling and heating are performed together. Cooling is also contrary to heating, and the cooling temperature is relatively lower than the heating temperature.

For example, according to the existing cooling process, since the mold heated by the heating means is cooled by the simple air cooling method, a method in which the portion closest to the heating means is cooled most recently is employed, whereby the size of the pore is gradated The gradation can not be obtained, and even if the gradation becomes possible, the width of the size change must be realized to a very small extent.

In order to compensate for these disadvantages, the present embodiment is characterized in that the polymer mixture is heated simultaneously with cooling so that the degree of crosslinking of the polymer mixture gradually differs, and the pores are graded according to the difference in degree of cross- It is possible to effectively incorporate the property change characteristic of the magnetorheic elastomer into the functional slanting foam unit and to extend the available range of energy absorption for shock and vibration of the functional slanting foam unit.

The present invention has the advantage of having excellent impact resistance and high energy absorption rate and excellent durability against elastic deformation according to a compressive force by making the polymer mold constituting the inclined self-tapering foam unit to be made of a polymer material and a magnetic reaction material .

The foaming agent saturation step (S130) is a step of applying pressure to the polymer mold in a pressure vessel (not shown) containing a liquid foaming agent so that the foaming agent is saturated inside the polymer mold.

The foaming agent saturation step (S130) may be performed such that the pores (101) are distributed in the polymer mold (100) in such a manner that the diameter gradually decreases in one direction in accordance with the gradual difference in degree of cross- The supercritical state of the blowing agent is maintained.

Here supercritical fluid means that, at high pressure, the object has intermediate properties between liquid and gas. The supercritical state has a high density of liquid and a high solvent velocity of the gas.

Therefore, when a blowing agent in a supercritical state (supercritical fluid) is used, the solubility and dissolution rate of the blowing agent in the polymer mold 100 can be maintained excellent. Accordingly, the effect of uniformly distributing the saturation of the foaming agent within the polymer mold 100 can be obtained within a short time.

In order to maintain the supercritical state of the foaming agent, the foaming agent saturation step (S130) is performed such that the pressure inside the pressure vessel is maintained at 7.5 to 10 MPa and the temperature is maintained at 40 to 60 ° C. The foaming agent saturation step (S130) maintains a temperature gradually lower than the curing temperature in the polymer mold forming step (S120) as shown in the graph of Fig. 4 for saturation of the foaming agent.

In addition, the foaming agent saturation step (S130) maintains a pressure gradually higher than the pressure in the polymer mold forming step (S120) as shown in the graph of Fig. 5 for saturation of the foaming agent. Therefore, the foaming agent saturation step (S130) allows the foaming agent to gradually saturate depending on the degree of cross-linking of the polymer template. Therefore, in the foaming agent saturation step (S130), the polymer template has directionality and gradually changes material saturation characteristics.

The pore forming step S140 may include a step of allowing the foaming agent to be phase-changed into a gaseous state inside the polymer mold 100 by removing the pressure applied in the foaming agent saturation step S130, Forming pores.

The pores formed in the pore formation step (S140) are formed by the carbon dioxide gas generated due to the phase change of the supercritical carbon dioxide used as the blowing agent. The pores are formed in the form of foam in the polymer mold, since the carbon dioxide gas can not escape from the polymer mold in the gel state and swells up.

By forming the pores in the polymer mold in the form of a foam, energy absorption characteristics can be maximized and a magnetic reaction to an external magnetic field can be effectively performed.

The pore formation step (S140) maintains the temperature condition in the foaming agent saturation step (S130) as shown in the graph of FIG. 4 for forming the pores. Meanwhile, the pore forming step (S140) gradually removes pressure under pressure conditions in the foaming agent saturation step (S130) as shown in the graph of FIG. 5, thereby forming pores.

Therefore, the pores formed by the pore formation step (S140) are formed in the polymer mold so that the diameter gradually decreases in one direction in accordance with the gradual difference in the degree of cross-linking of the polymer template, The change characteristics can be effectively incorporated into the functionally inclined foam unit, and the range of energy absorption for impact and vibration of the functionally inclined foam unit can be extended.

A portion of the polymer mold having a high degree of cross-linking has a low material saturation characteristic due to a high curing temperature. As a result, the pores have a small diameter size. On the other hand, in other portions where the degree of cross-linking is low in the polymer template, a low curing temperature results in a high material saturation characteristic. As a result, the pores have a relatively large diameter size.

 In the present invention, pressure generation and temperature control may be performed through a pressure generator (not shown) and a temperature controller (not shown). In addition, the present invention may include a control unit (not shown) for controlling the pressure generator and the temperature controller.

The curing step (S150) is a step of curing the polymer mold in which a plurality of pores are formed. The curing step (S150) cures the polymer mold for about 24 hours. The curing step (S150) maintains the temperature condition in the pore forming step (S140) as shown in the graph of FIG. Meanwhile, as shown in the graph of FIG. 5, the curing step (S150) maintains the pressure-removed state in the pore forming step (S140).

The magnetorheological function inclined foam unit manufactured through the polymer mixture forming step (S110), the polymer mold forming step (S120), the foaming agent saturation step (S130), the pore forming step (S140) and the curing step (S150) A polymer material capable of being deformed and a magnetically responsive material capable of a magnetic reaction by an external magnetic field, the energy absorption rate and rate of change of physical properties for impact and vibration are high.

In addition, due to the degree of saturation control of the polymeric mold using the gradual difference in curing temperature in the manufacturing process of the self-ramp function inclined foam unit, it is possible to realize the functional tilting structure for the thermally polymerizable polymer.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but is capable of numerous modifications and variations, It is obvious.

100: polymer mold 101: pores
200: forming mold 300: cooler
400: heater

Claims (7)

The present invention relates to a magnetorheological function inclined foam unit including a polymer mold capable of absorbing energy with respect to at least one of external impact and vibration,
Preferably,
A polymer material capable of elastic deformation, and a magnetic reaction material capable of a magnetic reaction by an external magnetic field,
And a plurality of pores so that an energy absorption rate and a property change rate can be improved. The method according to claim 1,
The pores,
Wherein the polymer mold is formed in a shape in which the diameter gradually decreases in one direction, thereby being distributed in the polymer mold. A polymer mixture forming step of mixing a polymer material capable of elastically deforming and a magnetoresistive material to form a polymer mixture;
Curing the polymer mixture to form a gel-state polymeric mold having an incremental difference in cross-linking degree;
A foaming agent saturation step wherein a pressure is applied to the polymer mold in a pressure vessel containing a liquid foaming agent so that the foaming agent is saturated inside the polymer mold;
Forming a plurality of pores in the polymer mold by causing the foaming agent to be phase-changed into a gaseous state inside the polymer mold by removing the pressure; And
And a curing step of curing the polymer mold having a plurality of pores formed thereon. The method of claim 3,
Wherein the polymer template forming step comprises:
Characterized in that the polymer mixture is accommodated in a molding mold and then the upper portion of the molding mold is cooled and at the same time the lower portion of the molding mold is heated so that the degree of crosslinking of the polymer mold gradually changes, Method of manufacturing inclined foam unit. The method of claim 3,
Wherein the foaming agent saturation step comprises:
Characterized in that the supercritical state of the foaming agent is maintained such that the pores are distributed in the polymer mold in such a manner that the diameter decreases gradually in one direction in accordance with the gradual difference in the degree of crosslinking, Unit manufacturing method. 6. The method of claim 5,
Wherein the foaming agent saturation step comprises:
Wherein the supercritical state of the foaming agent is maintained by maintaining the pressure and temperature inside the pressure vessel until the pore forming step. The method according to claim 6,
Wherein the foaming agent saturation step comprises:
Wherein the internal temperature of the pressure vessel is maintained at a temperature lower than a curing temperature at the time of curing the polymer mixture.

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