KR20060068807A - Manufacturing method of complex-shaped workpiece using powder injection molding and workpiece therefrom - Google Patents

Abstract

The present invention relates to a method for producing a complex shaped material using powder injection molding, and to a material prepared accordingly.

Homogeneously mixing the raw material powder with a binder to obtain a molding mixture; Using a powder injection molding apparatus, injecting the obtained molding mixture into a mold to form a molding; Machining the molding to the desired shape; Degreasing the binder from the molding; And sintering the degreased molding in a sintering furnace.

By appropriately mixing the powder injection molding method and the machining, it is possible to produce a high-performance complex shape material that is difficult or expensive to manufacture with conventional powder metallurgy at low cost.

Powder injection molding, machining, complex shape

Description

Manufacturing method of complex-shaped workpiece using powder injection molding and material produced according to the present invention {Manufacturing method of complex-shaped workpiece using powder injection molding and workpiece therefrom}

1 is a flow chart of a method of manufacturing a complex-shaped material according to an embodiment of the present invention,

2 is a flow chart of a method of manufacturing a complex-shaped material according to another embodiment of the present invention,

Figure 3a to 3i is a schematic diagram showing a heterogeneous powder injection molding process in the manufacture of a complex shape material according to another embodiment of the present invention,

4 is a flow chart of a method of manufacturing a complex-shaped material according to another embodiment of the present invention,

5 is a schematic view showing a multi-powder injection molding process in the manufacture of a complex-shaped material according to another embodiment of the present invention,

6a and 6b is a photograph of the complex shape material produced by an embodiment of the present invention,

7 is a schematic diagram showing various examples of the complex shape material produced by the present invention;

8 is a partial cutaway view of each material shown in FIG. 7.

<Description of Symbols for Main Parts of Drawings>

10: fixed mold 22: first moving mold

22a: injection hole 24: second moving mold

24a: injection hole 100: first layer

200: second layer 210: hopper for raw material supply

220: plasticization cylinder 230: injection screw

240: mold 242: injection hole

250: nozzles A1, B1, C1: molding mixture

A2, B2, C2: composite layer

The present invention relates to a method for producing a complex shape material using powder injection molding, and to a material prepared accordingly. More specifically, to prepare a material of complex shape using various raw materials such as metal or ceramic, powder injection molding method The present invention relates to a method for producing a complex-shaped material and a material produced according to the proper mixing and machining.

Various types of processing methods have been proposed to manufacture various tool materials or machine parts. Among these processing methods, powder metallurgy which obtains a metal product of the desired form by pressurizing and shaping | molding a metal powder, hardening | curing, and heating and sintering has attracted the spotlight.

Powder metallurgy enables the manufacture of products that are otherwise difficult or impossible to manufacture with other processing methods such as casting and forging.

For example, high-temperature materials such as tungsten, molybdenum, tantalum, refractory, ceramics, etc., which have a high melting temperature, are difficult to be manufactured through a melting method, but can be manufactured using powder metallurgy.

Alloys of non-soluble metals (tungsten-copper, iron-palladium), composite materials such as cemented carbide (tungsten carbide-cobalt), dispersion reinforcing materials, electrical contact materials, Composite materials of metal-nonmetals such as copper-graphite, materials having a layered structure such as dental amalgam, and the like can also be manufactured through powder metallurgy.

Porous materials such as bearings, filters or sponge-like materials cannot be obtained as castings but can be manufactured with powder metallurgy.

However, the processing technology using powder metallurgy had the following limitations.

First, in order to manufacture a molded body using powder, each powder layer injected into the mold must be pressurized with a punch-like mechanism. It was difficult to make.

In addition, since the process of injecting each powder layer into the mold is actually a situation that greatly depends on the manual work, there is a problem that the productivity is greatly reduced and the production cost is increased.

Powder injection molding technology has been proposed to overcome the limitations of the powder metallurgy technology.

Powder Injection Molding (PIM) is a fusion of injection molding technology developed in the plastics field and metal powder sintering technology developed in the powder metallurgy field. Its existing technologies such as cutting, precision casting, die casting and powder metallurgy It is a high-tech processing technology that enables mass production of high-performance complex precision parts that are difficult to manufacture or costly at low cost.

The general powder injection molding consists of a mixing process of powder and binder, injection molding process, debinding process, and sintering process. It is further classified into (Metal Injection Molding, MIM) or Ceramic Injection Molding (CIM).

However, in the case of powder injection molding, it is necessary to manufacture a mold for injection molding in order to obtain the required shape of the molded product. When the shape of the molded product is complicated, the problem of difficulty in manufacturing a mold and an increase in cost have arisen.

In particular, considering the characteristics of materials and parts that are becoming a small variety of materials, the production of complex molds each time in order to obtain a single molding shape inevitably causes a problem of reduced productivity and increased production cost.

The present invention has been made in view of the above problems, but the production of a complex shape material using a variety of raw materials such as metal or ceramics, the production of complex shape material made by mixing the powder injection molding method and machining appropriately Its purpose is to provide a method.

It is another object of the present invention to provide a material produced by such a production method.

The present invention for achieving the above object, the step of homogeneously mixing the raw material powder with a binder to obtain a molding mixture; Using a powder injection molding apparatus, injecting the obtained molding mixture into a mold to form a molding; Machining the molding to the desired shape; Degreasing the molding; And sintering the degreased molding in a sintering furnace.

According to another aspect, the present invention comprises the steps of homogeneously mixing at least two kinds of raw powder with each binder to obtain a molding mixture for each raw powder; Injecting a molding mixture forming a first layer of the obtained molding mixture into a mold by using a heterogeneous powder injection molding apparatus; Sequentially injecting the molding mixture constituting the second layer into the molding mixture constituting the last layer into the mold to form a composite layer molding integrally bonded from the first layer to the last layer; Machining the molding to the desired shape; Degreasing the molding; And sintering the degreased molding in a sintering furnace.

More preferably, the heterogeneous powder injection molding apparatus includes one fixed mold and at least two moving molds, and after forming a first layer by injecting a molding mixture into a space formed by the fixed mold and the first moving mold, The first moving mold is demolded and the second moving mold is fixed to the fixed mold to inject a molding mixture into the space formed by the fixed mold and the second moving mold to form a second layer, the same as the injection of the second layer. Repeat the process to form the last layer.

According to another aspect, the present invention comprises the steps of homogeneously mixing at least two kinds of raw powder with each binder to obtain a molding mixture for each raw powder; Using a multi-powder injection molding apparatus, a composite layer molding in which the molding mixture forming the first layer from the molding mixture forming the first layer to the molding mixture forming the last layer is injected into the mold, and integrally joined from the first layer to the last layer. Forming a; Machining the molding to the desired shape; Degreasing the molding; And sintering the degreased molding in a sintering furnace.

More preferably, the multi-powder injection molding apparatus is provided with at least two nozzles for injecting the molding mixture into the mold for each layer formation position, and simultaneously injections the molding mixture constituting each layer into the mold through the nozzles. Form a composite layer molding integrally bonded from one layer to the last layer.

More preferably, the raw material powder forming each layer is selected from the group consisting of metal powder, ceramic powder, carbide powder, glass powder, oxide powder, diamond powder or mixtures thereof.

More preferably, the binder is an organic binder, the molding mixture for each raw material powder is composed of the raw material powder 40 ~ 60 vol% and the remaining amount of the binder.

More preferably, the raw material powder and the binder are mixed homogeneously for 2 to 3 hours at a temperature condition of 80 ~ 150 ℃.

More preferably, the injection is made at an injection pressure of 1000 ~ 3000 psi in a state where the molding mixture is heated to 150 ~ 500 ℃.

More preferably, the machining is characterized in that the cutting.

More preferably, the degreasing is carried out in a pyrolysis method in a vacuum furnace, by heating at a temperature increase rate of 20 ~ 35 ℃ / hr from 80 ℃ to 600 ℃.

More preferably, the sintering is carried out under a reducing hydrogen atmosphere or a nitrogen atmosphere, when the raw material powder is made of metal powder or diamond powder, mixed powder thereof, the first temperature condition of 500 ~ 1300 ℃, the raw material powder is ceramic powder or When the powder is composed of carbide powder, glass powder, oxide powder, and mixed powder thereof, the second temperature condition of 1000 to 1500 ° C, and the raw material powder is a mixed powder of the powder of the first temperature condition and the powder of the second temperature condition It is made for a predetermined time while the third temperature condition of 500-1300 ° C is maintained.

The present invention is to produce a complex shape material using a variety of raw materials, such as metals, nonmetals, metal-divalent metal mixtures, metal-non-metal mixtures, and the powder injection molding method and machining is appropriately mixed.

In particular, the present invention further applies heterogeneous injection molding or multi-injection molding to general powder injection molding so that such a complicated material has a form of a composite layer material in which various raw materials are integrally combined while forming a separate layer.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a flow chart of a method for producing a complex shape material according to an embodiment of the present invention, Figure 2 is a flow chart of a method for producing a complex shape material according to another embodiment of the present invention, Figures 3a to 3i It is a schematic diagram showing the heterogeneous powder injection molding process in the manufacture of the complex-shaped material according to another embodiment.

The embodiment illustrated through FIG. 1 is to produce a complex shape material by mixing powder injection molding and machining, but to form a powder injection molding layer with only one layer. The embodiment illustrated through FIG. 2 is to further apply the embodiment of FIG. 1 to form a powder injection molding layer into several layers by heterogeneous powder injection molding.

Hereinafter, a description will be given of the embodiment of FIG. 2, which includes the embodiment of FIG. 1 and is further applied, and particularly illustrates a case in which a composite layer is formed by two kinds of raw material powders.

First, two kinds of raw powders are mixed homogeneously with each binder to obtain a molding mixture for each raw powder.

As the raw material powder, metal powder, ceramic powder, carbide powder, glass powder, oxide powder and diamond powder are used, and a mixed powder in which two or more of these powders are mixed as necessary may be used.

As the metal powder, for example, a powder made of Co, Cr, Fe, Cu, Zn, Ti, Ni, Ag, Sn, W, B, Mn, or an alloy thereof is used. As the carbide powder, for example, WC, TiC, CrC and the like are used, and as the ceramic powder, Zr, Si and the like are used.

The raw material powder is prepared in a size of about 1 to 20 μm. In the case of a larger size, the sintering property and the injection moldability are generally relatively poor and the strain due to shrinkage is large. It is difficult to uniformly mix with and the price is relatively high. However, the size of the raw material powder may be nano-size if the characteristics of the material is prioritized without considering the price, may be a size of several tens to several hundred μm in some cases.

As the binder, a conventional organic binder selected according to the raw material powder is used. For example, paraffin wax, vinyl acetate, polyolefin, ethylene vinyl acetate, and the like are used. Particularly, as the water-soluble binder, polyethylene glycol, polypropylene glycol, polyvinyl Alcohol and the like are used, and polystyrene, polyethylene and the like are used as the water-insoluble binder.

Each raw material powder and the binder are homogeneously mixed at a ratio of 40 to 60 vol% of the raw material powder and the remaining amount of binder, and then mixed for 2 to 3 hours at a temperature condition of 80 ~ 150 ℃. This mixing can be accomplished using, for example, a conventional double planetary mixer or the like.

When the raw material powder is less than 40 vol%, the fluidity during injection is good, but it takes a long time to degreasing. When the raw material powder is more than 60 vol%, the molding may not have sufficient strength during injection, so it is preferable to mix it to have the above mixing ratio. Do.

In addition, when the mixing is performed at a temperature lower than the above conditions or for a short time, the binder may not be mixed with sufficient fluidity. If the mixing is performed at a temperature above or above the above conditions, the binder may be degreased during mixing. Therefore, it is preferable to maintain the above mixing conditions.

As a result of the mixing, a molding mixture in which the raw material powder particles are wrapped in a binder is obtained. The molding mixture may form a lump by mutual bonding of the binders, but may be in powder form by a slight pressing force. Easily shredded.

Next, by using a heterogeneous powder injection molding apparatus, the molding mixture constituting the first layer of the obtained molding mixture is injected into the mold, and the molding mixture constituting the second layer is injected into the mold. The layers form integrally formed composite layer moldings.

Injection molding is one of the processing methods for forming a plastic material, especially a thermoplastic resin, and is a method of manufacturing a molded product by heating and melting a resin and then injecting it into a mold.

In particular, the heterogeneous injection molding is an injection molding method used for producing heterogeneous resins having different colors from one molding, for example, and is used for the manufacture of casings, keypads, and the like for home appliances. This heterogeneous injection molding is applied.

The heterogeneous powder injection molding apparatus of this embodiment has a conventional configuration provided with a hopper for raw material supply, a plasticizing cylinder, an injection screw, a mold, and the like, in particular, one fixed mold 10 and It has two moving molds 22 and 24.

In the injection process, the injection molding 22a of the first movable mold 22 is injected into the space formed by the fixed mold 10 and the first movable mold 22 to form the first layer 100. (FIGS. 3A-3C). The shape of the inner surface of the first moving mold 22 may be modified in various forms according to the shape of the second layer 200 required.

Thereafter, the first moving mold 10 is demolded (FIG. 3d), and the second moving mold 24 is fixed to the fixed mold 10 closely (FIG. 3e to FIG. 3f). In this state, the fixed mold 10 ) And the molding mixture is injected through the injection hole 24a of the second moving mold 24 in the space formed by the second moving mold 24 to form the second layer 200 (FIG. 3G). Although the inner surface of the illustrated second moving mold 24 is formed to have a flat surface, this may also be modified in various forms according to the shape of the second layer 200 required.

Subsequently, when the second moving mold 20 is demolded (FIG. 3H), the composite layer molding in which the first layer 100 and the second layer 200 are integrally combined (FIG. 3I) is obtained.

This injection is preferably made at an injection pressure of 1000 ~ 3000 psi in a state where the molding mixture is heated to 150 ~ 500 ℃.

If the injection temperature is lower than 150 ℃ may not be uniform injection molding because the fluidity of the molding mixture is not good, if higher than 500 ℃ may cause the evaporation of the binder, it is preferable to inject under the above conditions.

In addition, when the injection pressure is lower than 1000 psi, the molding mixture may not be injected smoothly from the nozzle, when the injection pressure is higher than 3000 psi, the powder injection molding apparatus may be overloaded, it is preferable to inject under the above conditions.

In particular, the injection is preferably performed by a three-point heating method under the above conditions. The three-point heating method controls heating and flow at at least three points such as an inlet, a break point, and an outlet through which the molding mixture is injected during the injection molding machine. This is how it is done.

On the other hand, the embodiment of Figure 1 uses only one type of raw material powder, injection molding apparatus is injection molding is performed through a similar process to the above, except that only a fixed mold and one moving mold is used. .

The injection process in the case where two or more raw material powders are used will be further described.

First, two or more kinds of raw material powders are mixed homogeneously with each binder to obtain a molding mixture for each raw material powder.

Next, by using a heterogeneous powder injection molding apparatus, a molding mixture constituting the first layer of the obtained molding mixture is injected into the mold, and then sequentially injected into the mold from the molding mixture constituting the second layer to the molding mixture constituting the last layer. Thereby forming a composite layer molding integrally joined from the first layer to the last layer.

At this time, the heterogeneous powder injection molding apparatus used has a conventional configuration provided with a hopper for supplying raw materials, a plasticizing cylinder, an injection screw, a mold, etc., in particular, one fixed mold and two or more in order to sequentially inject heterogeneous materials. It is equipped with a moving mold.

In more detail, the injection process is performed by injecting a molding mixture into the space formed by the fixed mold and the first moving mold to form a first layer, and then demolding the first moving mold and closely fixing the second moving mold to the fixed mold. Inject the molding mixture into the space formed by the stationary mold and the second moving mold to form a second layer, and repeats the same process as the injection of the second layer to form the last layer.

In the case of producing a so-called warp functional material, two or more kinds of powders may be mixed, but a mixed powder of a form in which only the mixing ratio is changed in several steps may be used. For example, A powder and B powder are mixed, but four kinds of mixed powders in which the mixing ratio is changed in a step of 1: 4-> 2: 3-> 3: 2-> 4: 1 are used.

The present embodiment may be particularly useful in the case of manufacturing such warp functional material, and may be usefully applied in the case of forming two or more materials as one composite layer material.

Next, the obtained molded product is machined into the required shape.

The molding obtained through the powder injection molding process described above is in a state having a predetermined hardness in a form similar to that of a general plastic injection molding, although there are some differences depending on the characteristics of the raw powder and the binder. In this step, these moldings are machined to the required final shape.

Mechanical working generally means processing to a desired shape and dimensions by changing the shape of the target material or changing mechanical properties by using a machine tool or a machine such as a rolling mill or press.

In particular, in the case of using a machine tool, a material such as metal is processed while cutting chips such as cutting and grinding to form a required shape, and a bite, drill bit, and milling to cut the material into a predetermined shape. Using a cutter such as a cutter, the material or cutter is rotated or reciprocated to force cutting.

Since the molding obtained through the above-mentioned powder injection molding process is in a state having a predetermined hardness, it is preferable that the final processing is performed to the required shape among the machining, in particular through cutting.

In other words, by using various kinds of machine tools such as lathes, drilling machines, boring machines, planers, milling machines, numerical control (NC) machine tools, the moldings obtained through the powder injection molding process are required. Precision machining

For example, when the required final shape has a cylindrical basic shape and a somewhat complicated process is required, the molding obtained through powder injection molding is precisely processed using a lathe.

As another example, when the required final shape is formed through holes of various shapes, the molding obtained through powder injection molding is precisely processed using a drilling machine.

This processing method, in the powder injection molding process is processed into a somewhat less complex molding form and machined only for the complex details as needed, making the mold required for powder injection molding much easier, It is possible to obtain moldings in a form that is extremely difficult or impossible to manufacture only by powder injection molding.

In particular, considering the characteristics of materials and parts that are becoming small quantities, this type of processing means avoiding the molds of complex shapes every time, thus reducing the productivity and increasing production costs. Will be provided.

Next, the molding is degreased.

Degreasing is a process of removing the binder added to the mutual binding of the raw material powder in the molding, in this embodiment degreasing is carried out by pyrolysis in a vacuum furnace, in particular in the temperature rise of 20 ~ 35 ℃ / hr from 80 ℃ to 600 ℃ By heating at a rate.

Looking at the degreasing process in more detail, a passage for degreasing the binder is formed in the injection molding in the initial temperature range, the degreasing of the low temperature binder is performed in the intermediate temperature range, and degreasing of the high temperature binder is performed sequentially in the high temperature range. . In this respect, it is preferable that degreasing is performed within the above temperature range.

In addition, from the technical aspect of the degreasing process, it is preferable that the temperature increase rate is low, but if the temperature increase rate is too low, the high temperature atmosphere of the vacuum furnace must be maintained for a long time, and as a result, the production cost is increased and the operating time is increased. It is desirable in terms of actual manufacturing to keep the rate of heating as high as possible under the conditions achieved. However, if the temperature increase rate is excessively high, since the warping and internal cracks, pores, swelling phenomenon may occur when degreasing, degreasing is preferable as the temperature increase rate.

The temperature increase rate of the vacuum furnace has an average meaning, and may be a method of continuously raising the temperature at a constant rate during the degreasing process, and if necessary, the process may be performed to include a process of temporarily stopping the temperature increase and maintaining a fixed temperature in the middle. It can also be operated.

Meanwhile, in such a degreasing process, the degreasing process of the solvent extraction method may be further performed. The solvent extraction method is a method of eluting and removing the binder by immersing the injected molding in a solvent.

At this time, the solvent used may vary depending on the type of the binder, for example methanol, butanol, hexane, dichromemethanol and the like can be used.

When such a solvent extraction degreasing process is added, it is preferable to make it go through as a previous stage of a thermal decomposition degreasing process.

Next, the degreased molding is sintered in a sintering furnace.

Sintering is performed under a reducing hydrogen atmosphere (or nitrogen atmosphere), but may be performed in a separate sintering furnace, but the sintering furnace may be configured by injecting hydrogen gas into a vacuum furnace in which degreasing is completed. When sintering is carried out under such a reducing hydrogen atmosphere, oxygen remaining in the molding is removed, so that voids are removed to obtain a dense structure, and the oxidation of the molding is also prevented.

When the raw powder is composed of metal powder or diamond powder, and mixed powder thereof, the raw powder is sintered under the first temperature condition of 500 to 1300 ° C. The raw powder is ceramic powder or carbide powder, glass powder, oxide powder, and mixed powder thereof. In this case, sintering is carried out under a second temperature condition of 1000 to 1500 ° C.

When the raw material powder is a mixed powder of the powder at the first temperature condition and the powder at the second temperature condition, the raw powder is sintered at a third temperature condition of 500 to 1300 ° C.

If the powder is sintered at a temperature lower than this temperature condition, the powder may not have sufficient hardness. At higher temperatures, the sintered powder may be thermally damaged, so it is preferable to maintain such a temperature condition.

At this time, the sintering process is performed for a predetermined time set according to the characteristics of each raw material powder or molding under the above temperature conditions. Such sintering time may be, for example, a time of about several minutes, or may be about 2 to 3 hours depending on the characteristics of the raw material powder or the molding.

Upon completion of this sintering, various shapes of complex shaped materials can be obtained, as illustrated in FIGS. 7 and 8.

FIG. 7A illustrates an example in which a drilling process is performed to obtain a shape required for a molded article of a hexahedron obtained by powder injection molding.

7 (b) shows a case where two materials A and B are formed as one composite layer material, and (c) shows a case where three materials A, B and C are formed as one composite layer material. The example in which the drilling process was performed so that the shape calculated | required by the molded object of the hexahedron obtained by this is obtained.

In the drawings, reference numerals h1 to h3 represent through holes drilled.

Although only drilling is illustrated in FIG. 7, various types of machine tools such as lathes, drilling machines, boring machines, planers, milling machines, and numerical control (NC) machine tools are considered in consideration of the shape of the molding and the required machining conditions. Using, various forms of machining can be achieved. In addition, although the illustrated moldings are hexahedron, the moldings of various shapes can be obtained by the powder injection molding process, which is a previous step.

On the other hand, for example in Figure 7 (b), it may be configured in the form of A (low-cost material) -B (expensive material), may be configured in the form of A (soft material) -B (hard material). And various material layers may be formed as one composite layer material, such as may be configured in the form of A (metal) -B (ceramic).

FIG. 8 is a partial cutaway view of each material shown in FIG. 7, further illustrating a drilled internal structure.

These complex materials, which consist of single or multiple layers, are characterized in terms of functionality and price, for example, watch bands, office equipment parts, electronic parts, parts of military equipment, parts in the semiconductor field, parts in the automotive field, parts for machine tools, etc. Complex shape (or composite layer) materials can be utilized in a variety of applications where required.

An embodiment of another aspect of the present invention will be described.

Figure 4 is a flow chart of a method of manufacturing a complex shape material according to another embodiment of the present invention, Figure 5 is a schematic diagram showing a multi-powder injection molding process in the production of a complex shape material according to another embodiment of the present invention.

In the above-described embodiment, when forming a complex material composed of a composite layer using two or more raw powders, the injection molding apparatus is used to sequentially perform injection molding for each material layer by applying a heterogeneous powder injection molding apparatus.

On the other hand, in this embodiment, two or more raw powders are used to form a complex shape material composed of a composite layer, and the multiple powder injection molding apparatus is applied to simultaneously inject two or more molding mixtures into each mold part. .

First, two or more kinds of raw material powders are mixed homogeneously with each binder to obtain a molding mixture for each raw material powder.

Next, by using a multiple powder injection molding apparatus, a composite layer which is injected into the mold from the molding mixture forming the first layer to the molding mixture forming the last layer in the obtained molding mixture, and integrally bonded from the first layer to the last layer. Form a molding.

The multi-powder injection molding apparatus of this embodiment has a conventional configuration provided with a hopper 210 for raw material supply, a plasticizing cylinder 220, an injection screw 230, a mold 240, and the like, in particular, a heterogeneous material (A1). At least two nozzles 250 and injection holes 242 for injecting the molding mixture into the mold in order to simultaneously inject the B1 and C1 into the respective parts are provided for each of the formation positions of the layers A2, B2 and C2.

In injection molding, the molding mixtures A1, B1, and C1 constituting each layer are simultaneously injected into the mold 240 through the nozzles 250 and the injection holes 242, and the final layer A2, B2, C2) to form a composite layer molding integrally combined.

In the multi-powder injection molding, two or more kinds of materials are injected at the same time, thereby producing a final product through the following process.

First, the number and position of nozzles into which the molding mixture is injected in each layer is determined according to the shape and thickness of the material layer required, and the flow path of the raw material flowing into the mold and the boundary point of each raw material formed in the molding based on the determined data. The simulation is performed by computer.

In the simulation process, the characteristics of the injection material and the injection conditions accordingly are considered together, and the above process is repeated so that the simulation result can be matched with the shape and thickness of the material layer required, and thus the number and position of the final nozzles, etc. The injection conditions will be determined.

Next, in consideration of the final shape and processing conditions required for the molding, using various kinds of machine tools such as lathes, drilling machines, boring machines, planers, milling machines, numerical control (NC) machine tools, Machined in the form.

Next, the binder is degreased from the molding and then sintered in a sintering furnace to obtain a final composite layer material.

Specific process conditions for each step may be applied in the same manner as in the above-described embodiment, and thus redundant descriptions thereof will be omitted.

This embodiment further provides the advantage that a multi-layered composite material can be manufactured by a single injection process.

<Example>

A) Co-Fe-based metal powder having a size of 1 ~ 5 ㎛ as a raw material powder was prepared, low density polypropylene (LDPE), high density polypropylene (HDPE), ethylene vinyl acetate (EVA), wax (WAX) as a binder Stearic acid was prepared.

Each prepared metal powder was mixed with the binder in a ratio of 1: 1, and was mixed for 2 hours while heated to a temperature of 120 ° C. using a double planetary mixer to obtain a molding mixture corresponding to A). It was.

Next, the above-mentioned A) molding mixture was injection molded using a powder injection molding apparatus to obtain two moldings having a hexahedral shape.

Injection was achieved by a three-point heating method, with all three points at an injection pressure of 2000 psi while being maintained at temperatures below 300 ° C.

Next, a hole of 1.4φ in one molding and 3.0φ in another molding was processed using a drilling machine.

Next, degreasing was carried out for each of the moldings by pyrolysis using a vacuum furnace. The vacuum furnace in the room temperature was heated to raise the temperature, but the average temperature increase rate during degreasing was 30 ℃ / hr, and the following temperature maintenance process was included during the temperature increase.

i) hold at 130 ° C. for 1 hour

ii) hold at 300 ° C. for 1 hour

iii) hold at 420 ° C. for 2 hours

Next, the molded product was sintered through a process subsequent to the degreasing process.

To this end, the vacuum furnace was continuously heated even after the degreasing step was completed, and hydrogen gas was injected into the inside of the vacuum furnace to form a reducing hydrogen atmosphere. In this state, the mixture was maintained at a temperature of 1000 ° C. for 2 hours and then cooled in a furnace.

6A and 6B are photographs of the complex shape material manufactured according to one embodiment of the present invention. FIG. 6A is a material in which a plurality of holes of 3.0φ are formed in a powder injection molding, and a final sintering treatment is performed. A number of holes of 1.4 phi are formed in the injection molding to represent each of the final sintered materials.

The present invention described above can be embodied in many different forms without departing from the spirit or main features thereof. Therefore, the above embodiments are merely examples in all respects and should not be construed as limiting.

The present invention, by appropriately mixing the powder injection molding method and the machining, it is possible to produce a high-functional complex shape material that was difficult or expensive to manufacture with conventional powder metallurgy at low cost.

Particularly, if this type of processing is used, the process of powder injection molding is carried out in the form of a somewhat less complicated molding, and machining only a complicated detailed shape as necessary, making the mold required for powder injection molding much easier. In addition, it is possible to obtain a molding of a form that is extremely difficult or impossible to manufacture by powder injection molding alone.

Further, the present invention further applies heterogeneous injection molding or multiple injection molding to powder injection molding to manufacture various materials such as metals or ceramics as one material in the form of a composite layer, and implements them through a simple process.

In addition, the present invention enables the use of an automated powder injection molding apparatus, thus providing the effect of greatly improving productivity and reducing production costs in the production of composite layer materials.

Claims (13)

Homogeneously mixing the raw material powder with a binder to obtain a molding mixture; Using a powder injection molding apparatus, injecting the obtained molding mixture into a mold to form a molding; Machining the molding to the desired shape; Degreasing the molding; And sintering the degreased molding in a sintering furnace. Homogeneously mixing at least two raw material powders with each binder to obtain a molding mixture for each raw material powder; Injecting a molding mixture forming a first layer of the obtained molding mixture into a mold by using a heterogeneous powder injection molding apparatus; Sequentially injecting the molding mixture constituting the second layer into the molding mixture constituting the last layer into the mold to form a composite layer molding integrally bonded from the first layer to the last layer; Machining the molding to the desired shape; Degreasing the molding; And sintering the degreased moldings in a sintering furnace. Homogeneously mixing at least two raw material powders with each binder to obtain a molding mixture for each raw material powder; Using a multi-powder injection molding apparatus, a composite layer molding in which the molding mixture forming the first layer from the molding mixture forming the first layer to the molding mixture forming the last layer is injected into the mold, and integrally joined from the first layer to the last layer. Forming a; Machining the molding to the desired shape; Degreasing the molding; And sintering the degreased molding in a sintering furnace. The method according to any one of claims 1 to 3, The raw material powder for forming each layer is selected from the group consisting of metal powder, ceramic powder, carbide powder, glass powder, oxide powder, diamond powder or mixtures thereof. . The method according to any one of claims 1 to 3, Wherein the binder is an organic binder, each of the raw material powder molding mixture is a method of producing a complex material using powder injection molding, characterized in that consisting of 40 ~ 60 vol% of the raw material powder and the remaining amount of the binder. The method of claim 5, The raw material powder and the binder is a method for producing a complex shape material using powder injection molding, characterized in that homogeneously mixed for 2 to 3 hours at a temperature condition of 80 ~ 150 ℃. The method of claim 5, The injection method is a method of producing a complex material using a powder injection molding, characterized in that the injection is made at a pressure of 1000 ~ 3000 psi in a state where the molding mixture is heated to 150 ~ 500 ℃. The method of claim 2, The heterogeneous powder injection molding apparatus has one fixed mold and at least two moving molds, After forming the first layer by injecting the molding mixture into the space formed by the stationary mold and the first movable mold, the first movable mold is demolded and the second movable mold is fixed to the stationary mold. Injection molding the molding mixture in this space to form a second layer, the method of producing a complex material using a powder injection molding, characterized in that to form the last layer by repeating the same process as the injection of the second layer. The method of claim 3, In the multiple powder injection molding apparatus, at least two nozzles for injecting a molding mixture into a mold are provided for each layer forming position. A method of producing a complex material using powder injection molding, characterized in that the molding mixture forming each layer is simultaneously injected into the mold through each nozzle to form a composite layer molding integrally bonded from the first layer to the last layer. The method according to any one of claims 1 to 3, The machining process is a method for producing a complex shape material using powder injection molding, characterized in that the cutting process. The method of claim 5, The degreasing is carried out in a pyrolysis method in a vacuum furnace, the method of producing a complex material using a powder injection molding, characterized in that the heating is carried out at a heating rate of 20 ~ 35 ℃ / hr from 80 ℃ to 600 ℃. The method of claim 4, wherein The sintering is carried out in a reducing hydrogen atmosphere or a nitrogen atmosphere, If the raw material powder is made of metal powder or diamond powder, and mixed powder thereof, the first temperature condition of 500 ~ 1300 ℃, When the raw material powder is composed of ceramic powder or carbide powder, glass powder, oxide powder, and mixed powder thereof, the second temperature condition of 1000 ~ 1500 ℃, When the raw material powder is a mixed powder of the powder at the first temperature and the powder at the second temperature, the powder injection molding is performed for a predetermined time while the third temperature is maintained at 500 to 1300 ° C. Method for producing a complex shaped material. Material prepared according to the method of any one of claims 1 to 3.

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