KR20150011852A - Device for high-density molding and method for high-density molding of mixed powder - Google Patents

Abstract

When the mixed powder containing the lubricant is filled in the first mold and the highest density of the intermediate powder compact capable of being formed by applying the first pressing force is 100%, a first pressing force is applied to the mixed powder, The mixed powder compacted intermediate compact is formed by heating at least 85% to less than 96% of the mixed powder compacted medium, and the temperature of the compacted powder compacted medium is heated to a temperature corresponding to the melting point of the powdered lubricant powder, Is set in a second mold which has been heated to a temperature equivalent to the melting point, and a second pressing force is applied to the mixed powder intermediate compact in the second mold to form a high-density powder mixture finished compact.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-

The present invention relates to a high-density molding method and a high-density molding apparatus capable of molding a high-density (e.g., 7.75 g / cm3) green compact by pressurizing the mixed powder twice.

In general, powder metallurgy technology is a technique in which a metal powder is pressed (compressed) to form a green compact of a predetermined shape, and then the green compact is heated to a temperature near the melting point of the metal powder to promote intergranular bonding (solidification) It is a series of techniques to perform processing. Thereby, it is possible to manufacture a machine part having a complicated shape and high dimensional accuracy at low cost.

In response to a request for further miniaturization and weight reduction of mechanical parts, improvement of the mechanical strength of the green compact is required.

On the other hand, it is known that when the green compact is exposed to a high-temperature atmosphere, the magnetic properties are deteriorated. For this reason, for example, in the actual production of the green compact, the subsequent high-temperature treatment (sintering treatment) may be omitted. In other words, a method of increasing the mechanical strength without sintering at high temperature has been sought.

Here, the mechanical strength is markedly increased (hyperbolic) as the density of the green compact is increased. As a representative densification method, there is proposed a method of pressurizing a metal powder by mixing a lubricant with a lubricant to reduce frictional resistance (for example, Japanese Patent Application Laid-Open No. 1-219101 (Patent Document 1)). In general, a mixed powder obtained by mixing about 1 wt% (1 wt%) of a lubricant with basic metal powder is press-formed. A number of proposals have been made aiming at higher density. These proposals are roughly divided into improvement of the lubricant itself and improvement of the processes of press molding and sintering treatment.

The former includes a proposal to use a lubricant as a carbon molecular complex comprising a ball-like carbon molecule and a plate-like carbon molecule (Japanese Patent Application Laid-Open No. 2009-280908 (Patent Document 2)), penetration at 25 ° C, (Japanese Patent Application Laid-Open No. 2010-37632 (Patent Document 3)). It is thought that both reduce the frictional resistance between metal powder and metal powder and metal mold.

Examples of the latter include warm-forming and sintered powder metallurgy methods (Japanese Patent Application Laid-Open No. 2-156002 (Patent Document 4)), handling facilitated warm-tempering powder metallurgy methods (Japanese Patent Application Laid-Open No. 2000-87104 5)), twice press-sintering powder metallurgy method (Japanese Patent Application Laid-Open No. 4-231404 (Patent Document 6)) and one-time sintering powder metallurgy method (Japanese Patent Application Laid-Open No. 2001-181701 Document 7)) is known.

The first warm compacting / sintering powder metallurgy method dissolves a part (or all) of the lubricant by dispersing the lubricant between the particles by preheating the metal powder mixed with the solid lubricant and the liquid lubricant. By doing so, the frictional resistance between the particles and between the particles and the mold is lowered, thereby improving the moldability.

The pre-warming-in-place powder metallurgy method is provided with a primary molding step for molding a primary compact having a low density (for example, a density ratio of less than 76%) capable of being handled by pressurizing the mixed powder prior to the warm- The secondary molded product (green compact) is obtained by subjecting the green compact to a secondary molding process while temporarily collapsing the primary molded product at a temperature lower than the temperature at which blue shortness occurs.

Two presses - Two sintering powder metallurgical methods produce a raw compact by pressurizing the iron powder mixture containing the alloying constituents in the die and preliminarily sinter the compact (compact) at 870 ° C for 5 minutes A preliminary sintered body is produced and the preliminary sintered body pressed twice is produced by pressing the preliminary sintered body and then sintering the preliminary sintered body pressed twice at 1000 캜 for 5 minutes to produce a sintered part.

The final one-time molding-sintered powder metallurgy method is a method in which a metal mold is preheated in advance and a lubricant is charged on the inner surface, and then a heated iron powder mixture (iron powder + lubricant powder) And then subjected to sintering treatment with an iron-based powder compact, followed by bright hardening, and then subjected to a tempering treatment to produce an iron-based sintered body .

As described above, the density of the green compact is at most 7.4 g / cm 3 (94% of the true density) even in the improvement of the lubricant, the press molding and the sintering process. Mechanical strength is insufficient. In addition, when the sintering treatment (high-temperature atmosphere) is carried out, the oxidation progresses in accordance with the temperature and the time, so that the lubricant in the powder particle coating state is burnt and residues are generated. As a result, the deterioration of the green compact quality after the pressure molding Resulting in a density of less than 7.3 g / cm 3. In addition, any improvement is complex and expensive. There is a difficulty in practicality due to inconvenience in handling.

In particular, it is pointed out that the density (7.3 g / cm 3 or less) is extremely unsatisfactory considering the production of the magnetic core (magnetic core or magnetic core) for electronic devices (motors and transformers) from green compacts. In order to reduce the amount of loss (iron loss and hysteresis) and increase the magnetic flux density, it is necessary to further increase the density of the green compact. For example, it is clear from the presentation material (provided by Toyota Central Research Institute Co., Ltd.) at the 2009 Powder Metallurgy Association's Fall Meeting. It is pointed out that the density of the magnetic core is unsatisfactory not only in terms of magnetic properties but also in mechanical strength, even if it is 7.5 g / cm 3, for example.

For the production of the green compact, a powder metallurgy method (Japanese Patent Application Laid-Open No. 2002-343657 (Patent Document 8)) has been proposed. The powder metallurgy method of this proposal is based on the technical idea that if the coating containing the silicone resin and the pigment is formed on the surface of the magnetic metal powder, the insulating property does not decrease even if the high temperature treatment is performed afterwards.

That is, the production method of the green compact has a step of preforming a magnetic powder whose surface is coated with a film containing a silicone resin and a pigment to form a preform, subjecting the preform to a heat treatment at a temperature of 500 ° C or higher, And then compression molding is performed with this heat treatment body. The temperature for the heat treatment is preferably in the range of 500 to 1000 占 폚 because the insulating film is decomposed at 1000 占 폚 or higher and the insulating property is lost when the temperature is lower than 500 占 폚. This high temperature treatment is performed in a vacuum, an inert gas atmosphere or a reducing gas atmosphere in order to prevent oxidation of the preform. Thus, it is described that a compacted magnetic core having a true density of 98% (7.7 g / cm 3) can be produced.

However, the sintering powder metallurgy method (patent document 8) for two times of molding and one time of sintering is more complicated and individualized than the other proposed methods, and is difficult to be implemented and practiced, resulting in a significant increase in manufacturing cost. It is also required that the preform is subjected to heat treatment at 500 ° C or higher. It is not suitable for mass production because it must be carried out in a special atmosphere in order to prevent deterioration of the quality of the concentrate core. Particularly, in the case of the magnetic metal powder coated with a glassy coating, the glassy body is deteriorated and melted, so that it can not be adapted.

In any of the above-mentioned proposed methods and apparatuses (Patent Documents 1 to 8), there is a description that can be carried out with respect to the sintering treatment in a relatively high temperature atmosphere, but details regarding the press-molding step are not clear. The description of the new improvement is not recognized for the analysis of the relationship between the specification and function of the pressure molding machine, the pressing force and the density, and the limit thereof.

The development of a method and an apparatus capable of manufacturing a high-density green compact (particularly, a high-density green compact for a magnetic core) reliably and stably at a low cost is required in view of the need for a higher mechanical strength along with the reduction in size and weight .

It is an object of the present invention to provide a high-density compacting method and a high-density compacting apparatus capable of producing a high-density green compact by performing pressure forming twice by inserting warming into mixed powder, .

Due to the fact that the green compact is manufactured from sinter metallurgical technology, it has become necessary to carry out sintering treatment of the green compact under pressure in a high temperature atmosphere (for example, 800 ° C or higher). However, the sintering high temperature treatment requires a large amount of energy consumption, which is not only costly, but also harmful for global environmental preservation.

Conventionally, the press-molding process is to establish a mixed powder as a specific form, and has been treated as such in the prior art (preliminary) mechanical treatment of the high-temperature sintering process. However, in actuality, the high temperature treatment for sintering is dispensed with only in the case of producing a green compact for use in an electronic device (motor, transformer, etc.). And avoids harmful effects (deterioration of magnetic properties) in the case of high temperature treatment. In other words, there was no choice but to tolerate dissatisfaction with mechanical strength. The lack of mechanical strength is a matter of density, and of course magnetic properties are also insufficient.

Therefore, if the high-density compacting of the green compact can be performed only by the pressure molding process without the high-temperature sintering process, the industrial use and diffusion of the green compact can be dramatically improved.

The present invention relates to a lubricant composition comprising a lubricant at the time of pressurization, a compression limit including a lubricant powder, a spatial viscosity of the lubricant powder in the mixed powder, a spatial arrangement state of the base metal powder and the lubricant powder or their mobility, Based on the analysis of the characteristics of general press machine, compressibility limit, and density of green compacts on strength and magnetism, it is also possible to promote the shortening of the actual manufacturing cycle .

That is, the present invention is characterized in that the first metal mold is filled with a mixed powder obtained by mixing a base metal powder with a powder lubricant, and an intermediate green compact having a true density ratio of 85 to 96% is formed by a first pressing step while maintaining the powder state of the lubricant And then the lubricant is heated and liquefied to change the lubrication pattern in the intermediate-pressure powder. Thereafter, the second pressurizing process is carried out to form a high-density finished green compact having a density close to the true density.

In other words, a high-density green compact can be reliably and stably produced at a low cost by the creation of a new powder metallurgy technique (two press molding with a liquefying process inserted) deviating from the conventional sinter metallurgical technique which requires high-temperature sintering treatment And to provide a breakthrough and practical method and apparatus that can be used in the present invention.

(1) In detail, in the high-density molding method for a mixed powder according to the first aspect of the present invention, a first metal mold is filled with a mixed powder obtained by mixing a base metal powder with a lubricant powder having a low melting point, And the maximum density of the compactable intermediate powder compact is 100%, the first pressurizing force is applied to the mixed powder in the first mold to form a mixed powder compact having a density ratio of 85 to 96% , The mixed powder intermediate compact drawn out from the first mold is heated to raise the temperature of the mixed powder compact intermediate body to the temperature corresponding to the melting point of the lubricant powder and the temperature of the mixed powder compact is set in the second mold , And a second pressing force is applied to the mixed powder intermediate compact in the second mold to mold the finished mixed powder compact.

(2) In the above invention (1), the melting point of the lubricant powder can be set to a low melting point falling within a temperature range of 90 to 190 占 폚.

(3) In the invention of (1) or (2) above, the second mold may be preheated to a temperature corresponding to the melting point before the mixed powder is compressed.

(4) In the above invention (1) or (2), the second pressing force is equal to the first pressing force.

(5) The high-density forming apparatus for a mixed powder according to the second aspect of the present invention comprises a mixed powder feeder capable of supplying a mixed powder obtained by mixing a base metal powder with a lubricant powder having a low melting point, A first pressurizing device for applying a first pressing force to the mixed powder filled in the first mold by using the first press molding machine to form a mixed powder intermediate compact; And a second pressurizing force is applied to the temperature-increased mixed-powder intermediate pressurizing body set in a second mold having an end which has been heated to have a high temperature And a second press-molding machine for molding the mixed powder-finished compression body, wherein the first press-molding machine is capable of forming a compact Has a first intermediate mixture of the first to apply a first pressing force to the art mixed powder density ratio of 85% to 96% in the mold powder compact body is formed to be molded in a case where the density of 100%.

(6) In the above invention (5), the heating and heating apparatus and the second press molding apparatus may be formed by a heating and pressing apparatus integrally including these functions, and the heating and pressing apparatus may be constituted by a plurality of heating- ), And each of the heating and pressure-molding magnets is selectively operated in cycles.

(7) In the invention according to (5), the apparatus may have a warming apparatus for warming the second mold.

(8) In the invention according to (5), the mixed powder intermediate compact formed in the first press-molding machine is transferred to the heating and raising unit, and the mixed powder intermediate compact, And a workpiece transferring device for transferring the mixed powder-finished compression body molded in the second press-molding machine to the discharge portion.

According to the invention (1), the high-density green compact can be reliably and stably manufactured, the manufacturing cost can be greatly reduced, and the shortening of the actual production cycle can be promoted while securing the safety of the apparatus have.

According to the invention (2), sufficient lubricating action can be ensured while suppressing oxidation of the lubricant in the first pressurizing step. Also, the selectivity for the type of lubricant is wide.

According to the invention (3), since the flowability of the dissolved lubricant in all directions in the second press forming can be further enhanced, not only the inter-metallic particles but also the frictional resistance between the particles and the second metal mold can be greatly reduced .

According to the invention described in (4) above, it is easy to carry out the press forming step and to handle it, and indirectly contribute to further reduction of the production cost of the green compact.

According to the invention (5), the high-density molding method of the mixed powder according to the above items (1) to (4) can be reliably carried out, and its implementation is easy and handling is simple.

Further, according to the invention of (6) above, the device can be simplified in comparison with the case of the invention of (5). The simplification of the manufacturing line can be promoted and the handling can be further facilitated.

According to the invention of the above (7), even when the temperature of the mixed powder compact can be lowered by the start of the completion green compacting by warming up the second mold, the mixed powder compact can stay within a constant temperature range A good molding effect can be obtained.

According to the invention of (8) above, by having the workpiece conveying device, it is possible to control the distance between the first pressure molding machine and the heating / warming unit, between the heating / warming unit and the second pressure molding machine, The work can be reliably transferred to the workpiece.

Further, the constitution and effects of the present invention other than the above will be apparent from the following description.

1 is a view for explaining a high-density molding method according to the present invention.
2 is a front view for explaining a high-density molding apparatus and operation according to the first embodiment of the present invention.
Fig. 3 (A) is a view for explaining the high-density molding operation of the mixed powder in the first embodiment of the present invention, and shows a state in which the intermediate green compact is molded by the first metal mold.
Fig. 3 (B) is a view for explaining the high-density molding operation of the mixed powder in the first embodiment of the present invention, and shows a state in which the following mixed powder is filled in the first mold.
Fig. 4 is a graph for explaining the relationship between the pressing force in the first embodiment of the present invention and the density obtained by the pressing force, and the characteristic A (curve) Represents a molding state in the second mold.
5A is an external perspective view for explaining a finished green compact (intermediate-pressure powder) according to the first embodiment of the present invention, and shows a ring shape.
Fig. 5 (B) is an external perspective view for explaining a finished green compact (intermediate-pressure powder) according to the first embodiment of the present invention, and shows a columnar shape.
Fig. 5C is an external perspective view for explaining the finished green compact (intermediate-pressure powder) according to the first embodiment of the present invention, and shows an elongated round shaft shape.
Fig. 5D is an external perspective view for explaining a finished green compact (intermediate-pressure powder) according to the first embodiment of the present invention, and shows a disc shape.
Fig. 5 (E) is an external perspective view for explaining the finished green compact (intermediate-pressure powder) in the first embodiment of the present invention, showing a complicated shape.
6 is a front view for explaining a high-density molding apparatus and operation according to a second embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

(First Embodiment)

As shown in Figs. 1 to 5 (E), the high-density molding apparatus 1 of the present mixed powder is composed of a mixed powder feeder 10, a first press molding machine 20, a heating and warming machine 30 and a second press molding machine (PR1) for filling the first metal mold (lower mold (21)) with the mixed powder (100) obtained by mixing the base metal powder with the lubricant powder having a low melting point, the first pressing force (P1) The first pressing force P1 is applied to the mixed powder in the first mold (lower mold 21) so that the density ratio becomes 85 to 96% when the maximum density of the moldable intermediate powder compact is 100% The intermediate-pressure powder compacting step PR2 for forming the intermediate powder compact 110 (sometimes called the intermediate-compact powder 110) of the mixed powder of the intermediate powder compact 110 and the intermediate-compact powder 110 drawn out from the first mold (lower mold 21) A heating heating step (PR3) in which the temperature of the intermediate green compact (110) is heated to actively raise the temperature to the melting point equivalent temperature of the lubricant powder, A second pressing force P2 is applied to the intermediate green compact 110 in the step PR4 of setting the green compact 110 in the second mold (lower mold 41) and the second mold (lower mold 41) A high-density powder compacting process (PR5) for forming a compacted compact (sometimes referred to as a finished compact powder 120) is carried out stably and reliably.

The mixed powder (100) in the present specification means a mixture of a base metal powder and a lubricant powder having a low melting point. In addition, the base metal powder may be composed of only one kind of main metal powder, one kind of main metal powder and one or more alloying component powders mixed therein, but it can be adapted in any case.

The low melting point is a temperature (melting point) at which the temperature (melting point) is remarkably lower than the melting point (temperature) of the base metal powder and a temperature (melting point) at which oxidation of the base metal powder can be suppressed to a large extent it means.

2 showing the high-density molding apparatus 1, the mixed powder feeder 10 disposed at the leftmost (upstream) side of the high-density molding line is configured so that the mixed powder 100 constitutes a part of the first press molding machine 20 Is supplied to the first mold (lower mold 21) and charged into the cavity 22. (Positions indicated by solid lines in FIGS. 2, 3A and 3B) and a first mold (lower mold 21) having a function of storing a predetermined amount of mixed powder 100 and a function of supplying a fixed amount, (A position indicated by a dotted line in Fig. 3 (A) and Fig. 3 (B)).

Since it is important to uniformly and sufficiently fill the mixed powder 100 in the first mold (the lower mold 21), the mixed powder 100 should be in a state of being smoothly transported. That is, since the shape of the inner space (cavity 22) of the first mold (lower mold 21) is a shape according to the product shape, even if the shape of the product is complicated or narrow, Non-uniform charging or inadequate charging is not desirable to ensure accuracy.

The shape (dimensions, shape) of the finished green compact 120 (intermediate green compact 110) is not particularly limited, but is shown in Figs. 5 (A) to 5 (E) as an example. Fig. 5 (A) shows a ring shape, Fig. 5 (B) shows a columnar shape, Fig. 5 (C) shows a round and round shape, Fig. 5 (D) shows a disc shape and Fig.

That is, the upper mold (upper punch) 25 of the first press molding machine 20 and the cavity 22 of the lower mold 21 have a shape corresponding to the shape (shape) of the intermediate green compact 110. When the shape of the intermediate green compact 110 is, for example, those shown in Figs. 5 (A) to 5 (E), the shape corresponds to each of them.

When the shape of the intermediate green compact 110 is a ring shape as shown in Fig. 5A, the shape of the upper mold (upper punch) 25 as shown in Figs. 2, 3A, And the shape of the lower mold 21 becomes a hollow circular cylinder shape. In the case of the cylindrical shape shown in Fig. 5 (B), the upper mold (upper punch) 25 has a hollow cylindrical shape and the lower mold 21 has a hollow cylindrical shape. 5 (C), and the elongated round shape of FIG. 5 (D) (although there is a deep and shallow difference therebetween). In the case of the complex shape shown in Fig. 5 (E), the shape is complicated. The upper mold (upper punch) 45 of the second press molding machine 40 and the cavity 42 of the lower mold 41 are also the same.

Here, the lubricant for reducing the frictional resistance between the particles of the base metal powder and the frictional resistance between the base metal powder and the inner surface of the metal mold is selected as a solid (very small granular), i.e., powder, smoothly transported at room temperature . For example, when a liquid lubricant is employed, the viscosity of the mixed powder 100 is high and the fluidity is low, so that uniform charging or sufficient charging can not be performed.

Next, the lubricant during the intermediate-pressure powder molding performed while applying the first pressing force P1 in the first mold (lower mold 21) under normal temperature is solid and can maintain a predetermined lubrication effect stably It must be. Even if there is a case where a slight temperature rise occurs due to the application of the first pressing force P1, it should be maintained in a stable manner.

On the other hand, from the viewpoint of the relationship with the heating temperature raising step (PR3) and the inhibition of oxidation of the base metal powder, the melting point of the lubricant powder is set to a very low melting point (low melting point) There is a need.

In the present embodiment, the melting point of the lubricant powder is selected to be a low melting point falling within a temperature range of 90 to 190 占 폚. The lower temperature (90 占 폚) is set so that the upper limit temperature (80 占 폚) of a value (for example, 70 to 80 占 폚) which will not reach this temperature even when a certain temperature rise occurs during the intermediate- (For example, 90 占 폚), and additionally attention is paid to the melting point (for example, 110 占 폚) of another metallic soap. That is, it is possible to eliminate the possibility that the lubricating oil powder is dissolved (liquefied) and flowed out during the press-molding of the intermediate green compact.

The upper temperature (for example, 190 占 폚) is selected as the minimum value from the viewpoint of expanding the selectivity with respect to the kind of the lubricant powder, and in particular, from the viewpoint of inhibition of oxidation of the base metal powder in the heating and heating step. That is, the lower temperature and the upper temperature in this temperature range (90 to 190 ° C) are not limit values and can be understood as a threshold value.

As described above, many substances belonging to the metal soap (zinc stearate, magnesium stearate, etc.) can be selectively employed as the lubricant powder. In addition, since the lubricant must be in a powder state, viscous liquid such as zinc octylate can not be employed.

In this embodiment, zinc stearate powder having a melting point of 120 ° C was used as a lubricant powder. In the present invention, as in the case of the invention of Patent Document 7, the idea of performing press molding while using a lubricant having a temperature (melting point) lower than the mold temperature at the time of pressure molding and dissolving (liquefying) the lubricant from the beginning is denied . If the lubricant dissolved before the molding of the intermediate green compact 110 has flowed out, a portion lacking in lubricating property tends to be generated in the middle, so that sufficient pressure molding can not be reliably and stably carried out.

The amount of lubricant powder shall be the value selected from the experimental study and the empirical rule through actual production. Firstly, in relation to the intermediate green compact forming process (PR2), the amount of the lubricant powder is set to 0.23 to 0.08 wt% of the total amount of the mixed powder. 0.08 wt% is a lower limit value capable of ensuring lubricating action until the end of forming the intermediate green compact 110, 0.23 wt% is obtained by obtaining a compression ratio expected when the intermediate powder compact 110 is changed from the mixed powder 100 It is the upper limit value necessary for.

Next, the amount of the lubricant powder to be produced is determined by the value of the true density ratio of the intermediate-pressure powder 110 molded by applying the first pressing force in the first mold (lower mold 21) ) Should be determined to be capable of securing perspiration (发汗). At this time, it should not be overlooked that the phenomenon of dropping of the liquid drop of the liquefied lubricant from the mold causing deterioration of the working environment is not missed.

In this embodiment, the value of the true density ratio (ratio to true density of 100%) of the intermediate green compact 110 is set to 80 to 90%, so that the amount of the lubricant powder is set to 0.2 to 0.1 wt%. The upper limit value (0.2 wt%) is determined from the viewpoint of preventing the phenomenon of dropping of the droplets, and the lower limit value (0.1 wt%) is determined from the viewpoint that sufficient sufficient sweating phenomenon is possible without excess or deficiency. Is extremely small as compared with the case of the above-mentioned conventional example (1 wt%), and the usability in industry can be greatly improved.

Prevention of drop phenomenon is extremely important for actual production. There is a tendency to mix too much of the excess lubricant in the tabletop design or in the research stage with the fear that the lubricant will be insufficient in view of the reduction of the frictional resistance under pressure. For example, it is in trial and error stage whether or not densification exceeding 7.3 g / cm3 occurs, so that it is totally indifferent to the situation where excessive lubricant liquefies and leaks out of the mold. There is no recognition of the drop phenomenon. That is, the drop of the liquid drop of the liquefied lubricant leads to an increase in the cost due to an increase in the lubricant usage fee, a decrease in the productivity due to the deterioration of the working environment, and an increase in burden on the operator. Do not.

In the case of the intermediate-pressure powder 110 in which 0.2 wt% of the mixed powder 100 is compressed to a true density ratio of 80%, when the temperature is elevated positively to the melting point equivalent temperature of the lubricant powder in the heating raising step PR3, The powdery lubricant that fills the inside of the intermediate powder 110 passes through the gap between the metal powders, and the lubricant is uniformly injected into the surface of the intermediate powder 110 ( . That is, sweating is caused. When the intermediate green compact 110 is compressed by applying the second pressing force P2 in the second mold (lower mold 41), the frictional resistance between the base metal powder and the cavity inner wall is greatly reduced.

Even in the case of the intermediate-pressure powder 110 in which 0.1 wt% of the mixed powder 100 is compressed to a true density ratio of 90%, the mixed powder 100 having a value exceeding 0.1 wt% and less than 0.2 wt% The same sweating phenomenon can be exhibited even in the case of the intermediate-pressure powder 110 in which the ratio is less than 90% and compressed to a value in a range exceeding 80%. It is possible to prevent the phenomenon that the droplets fall off.

In this manner, high-density molding can be performed, and a green compact (for example, a magnetic core) satisfying not only magnetic characteristics but also mechanical strength can be manufactured, and the risk of mold breakage can be reduced. In addition, the consumption amount of the lubricant can be greatly reduced, and the liquid lubricant does not flow from the second mold (lower mold 41), and the working environment is improved. As a whole, the productivity is improved and the production cost of the green compact is reduced, so that the industrial usability can be remarkably improved.

In any of the above-described conventional methods and apparatuses (Patent Documents 1 to 8), there is no recognition of the relationship between the content of the lubricant and the compressibility of the mixed powder, the drop of the liquid drop caused by a slight amount of the lubricant, and the sweating phenomenon.

Particularly, even in the case of the warm powder metallurgy method (Patent Document 5), it is understood that a primary molded body having a density ratio of less than 76% is molded for easy handling. However, no technical basis and high feasibility of high density molding are disclosed It is not. In the point that the secondary molded body is molded after collapsing the primary molded body once after that, it is no better than denying the technical idea for achieving high density due to the duplicated molding of the primary molding and the secondary molding.

The first press molding machine 20 applies the first pressing force P1 to the mixed powder 100 filled in the first mold (lower mold 21) by using the mixed powder feeder 10, The green compact 110), and in the present embodiment, it is a press machine structure.

In Fig. 2, the first mold apparatus is composed of a bolster die (die) 21 and a top (punch) 25 on the slide 5 side. The cavity 22 of the lower mold 21 has a shape corresponding to the shape (ring shape) of the intermediate green compact 110 shown in Fig. 5A (hollow circular cylinder shape). That is, the upper mold (upper punch) 25 is in a form capable of being press-fit into the lower mold 21 (cavity 22) (a toric shape shown in Figs. 2, 3A and 3B) (5). Below the cavity 22, a movable member 23 is vertically displaceably mounted.

The upper mold (upper punch) 25 and the cavity 22 of the lower mold (dies) 21 of the first pressure molding machine 20 have a shape corresponding to the shape (shape) of the intermediate green compact 110, Even when the shape of the powder 110 is the one shown in Figs. 5 (B) to 5 (E). The upper mold (upper punch) 45 of the second press molding machine 40 and the cavity 42 of the lower mold 41 are also the same.

The movable member 23 is displaced upward by a knockout pin (not shown) pushed through the through hole 24 provided below the ground level GL. That is, the intermediate green compact 110 in the first mold (lower mold 21 (cavity 22)) can be pushed up to the transfer level HL. And functions as a first drawing device for drawing the intermediate green compact 110 in the first mold (lower mold 21) to the outside HL when viewed from the outside. After the intermediate green compact 110 is transferred to the heating / heating unit 30 side, the movable member 23 returns to the initial position together with the knockout pin. The first drawing device may be formed with another special device.

The relationship between the pressing force P (the first pressing force P1) in the first press molding machine 20 and the density ratio (density?) Of the intermediate green compact 110 obtained corresponding thereto will be described with reference to FIG. The abscissa represents the pressing force P as an exponent. The maximum capacity (pressing force P) in this embodiment is 10 Ton / cm < 2 > Pb is the die breakage pressure, and the transverse index is 140 (14Ton / cm2). The vertical axis represents the density ratio (density?) As an index. The longitudinal axis index 100 corresponds to a true density ratio (density?) Of 97% (7.6 g / cm3).

In the present embodiment, the base metal powder is a zinc stearate powder having a glassy insulated coating-coated iron powder for magnetic core (true density is 7.8 g / cm 3) and a lubricant powder is 0.2 to 0.1 wt% It is selected to be capable of compressing the powdered intermediate compact to 80 to 90% of the true density ratio corresponding to the longitudinal axis index 82 to 92 [density ρ (equivalent to 6.24 to 7.02 g / cm 3)].

The longitudinal axis index 102 corresponds to the density rho (7.75 g / cm3), and the true density ratio (density rho) corresponds to 99%.

The base metal powder may be an amorphous powder for magnetic core (Fe-Si alloy powder for magnetic core), an iron-based amorphous powder for magnetic core, an Fe-Si alloy powder for magnetic core, or pure iron powder for machine parts.

When the first pressing force P1 is increased, the density p obtained by the first pressing machine 20 becomes higher according to the characteristic A (curve) shown in Fig. The density? Is 7.6 g / cm3 at the first pressing force P1 (transverse index 100). The true density ratio is 97%. Even when the first pressing force P1 is increased to a value higher than the first pressing force P1, the improvement of the density p is extremely small. There is a strong concern about mold damage.

Conventionally, when the density p obtained by pressing with the maximum capacity of a press molding machine (press machine) can not be satisfied, it is necessary to equip a larger press machine. However, even if the maximum capacity is enlarged to, for example, 1.5 times, the improvement in density ρ is slight. In this way, it has been in fact compromised by the low density? (For example, 7.5 g / cm3) obtainable by the present press machine.

Therefore, it can be understood that if the present press machine can be used as it is, it can be improved from the longitudinal axis index 100 (7.6 g / cm 3) to 102 (7.75 g / cm 3). That is, if the density rho can be improved by 2%, the magnetic properties can be greatly improved (hyperbolic), and the mechanical strength can also be drastically improved. In addition, since the sintering treatment in a high temperature atmosphere can be performed one at a time, oxidation of the green compact can be suppressed to a large extent (deterioration of the magnetic core performance can be prevented).

(Liquefaction) of the lubricant is promoted by heating the intermediate-pressure powder 110 molded by the first press-molding machine 20, and then the second press-molding process is performed in the second press-molding machine 40 As shown in Fig. When the intermediate green compact 110 is pressed in the second press molding machine 40, a high density (7.75 g / cm 3) corresponding to the longitudinal axis index 102 can be achieved as shown by the characteristic B (straight line) in FIG. The details will be further explained in the description of the second press molding machine 40.

The heating / warming-up device 30 heats the mixed powdered intermediate compact (intermediate-compact powder) 110 drawn out from the first mold (lower mold 21) and adjusts the temperature of the intermediate-compacted powder 110 to the melting point It is a device that actively warms up at a considerable temperature. 2, the heating / warming-up unit 30 includes a warm air generating source (not shown), an atomizing hood 31, an exhaust circulating hood 33, and the like. ), And the temperature is raised to a temperature equivalent to the melting point of the lubricant powder (for example, 120 DEG C).

The technical significance of this low-temperature heat treatment will be described in relation to the first press-molding process. Observation of the mixed powder 100 filled in the lower mold 21 (cavity 22) reveals that the presence of the lubricant powder in the relationship with the base metal powder results in a comparatively rough portion (small portion) and a dense portion (dense portion) . The pressed portion can reduce the frictional resistance between the particles of the base metal powder and the frictional resistance between the base metal powder and the inner surface of the mold. These areas will have greater frictional resistance.

The portion pressed in the first pressing machine 20 during the pressing is low-friction, and therefore, the compression is excellent and the compression is likely to progress. Since the lower part is high friction, the compressibility is inferior and the compression is slowed down. In any case, it is difficult to progress the compression in accordance with the value of the first pressing force P1 set in advance. That is, a compression limit occurs.

When the fracture surface of the intermediate green compact 110 drawn out from the metal mold 21 under such a magnified condition is enlarged and observed, the base metal powder is pressed in an integrated manner in the portion which was the pressed portion. However, the lubricant powder is also mixed. There was a small gap (space) between the metal powders that had been pressed. The lubricant powder is hardly noticeable.

Removal of the lubricant powder at such a dense portion results in a compressible gap. If lubricant can be supplied to the gap of the portion which is the small portion, the compressibility of the portion can be increased.

That is, the intermediate green compact 110 after the completion of the first press-molding is heated to raise the temperature to a temperature corresponding to the melting point of the lubricant powder (for example, 120 占 폚) to dissolve (liquefy) the lubricant powder to improve its fluidity. Lubricants that melted out from the area where it was dense penetrated into the surrounding area and became widespread in the area where it was the weak area. Therefore, the frictional resistance between the particles of the base metal powder can be reduced, and the space occupied by the lubricant powder can be compressed. The frictional resistance between the particles of the base metal powder and the inner surface of the metal mold can be reduced.

Next, the second press molding machine 40 applies the second pressing force P2 to the elevated intermediate green compact 110 set in the second mold (lower mold 41) to form a high-density finished green compact 120. [ As shown in Fig.

In the present embodiment, the warming function of the second mold (lower mold 41) is provided. However, when the temperature of the intermediate green compact 110 in which the temperature has been raised is lower than the temperature at which the molding is started until the start of molding of the finished green compact in which the second pressing force P2 is applied in the second mold (lower mold 41) The high-density molding of the present invention can be carried out without heating the second mold if it is within a certain temperature range.

However, when the heat capacity of the intermediate green compact 110 is small and the transfer time to the second metal mold or the conveying path is long, the intermediate green compact 110 that has been heated by the composition of the mixed powder or the shape of the intermediate green compact 110 110) is likely to lower the temperature by the start of the complete green compact start, it is possible to obtain a good molding effect by warming up the second mold (lower mold 41). The second warming-up device 47 described later is installed for this reason.

The maximum capacity (pressing force P) of the second press molding machine 40 in this embodiment is 10 Tons / cm < 2 > as in the case of the first press molding machine 20. Thus, the first press molding machine 20 and the second press molding machine 40 are constituted as one press machine, and the upper and lower molds 25 and 45 are moved up and down synchronously by the common slide 5 shown in Fig. 2 . In this respect, the economical efficiency of the apparatus is also advantageous, and the production cost of the finished green compact 120 can be reduced.

In Fig. 2, the second mold apparatus is composed of a bolster 41 (lower die) and an upper mold (punch) 45 on the slide 5 side. The lower part of the cavity 42 of the lower mold 41 has a shape corresponding to the shape of the finished green compact 120 (ring shape) and the upper part can accommodate the intermediate green compact 110 It is a slightly larger form.

The upper mold 45 is formed into a shape that can be press-fit into the lower mold 41 (cavity 42), and the lifting and lowering motion is performed by the slide 5. [ A movable member 43 is inserted in the lower portion of the cavity 42 so as to be displaceable in the vertical direction. The second mold (lower mold 41) and the first mold (lower mold 21) are arranged at a height corresponding to the vertical dimension difference between the compression target (intermediate green compact 110 and the finished green compact 120) ) Has been adjusted.

The movable member 43 is displaced upward by a knockout pin (not shown) protruding through the through hole 44 provided below the ground level GL. That is, the finished green compact 120 in the second mold (lower mold 41 (cavity 42)) can be pushed up to the transfer level HL. And functions as a second drawing device for drawing the finished green compact 120 in the second mold (the lower mold 41 (cavity 42)) to the outside HL when viewed from the outside. The second drawing device may be formed by another special device.

After the finished green compact 120 is discharged to the discharge shoe 59 and the new intermediate green compact 110 is received from the heating / heating unit 30, the movable member 43 returns to the initial position together with the knockout pin.

The second mold (lower mold 41) is provided with a second warming device 47 capable of changing the set temperature. The second warming apparatus 47 is provided with a second mold (lower mold 41) at a temperature equivalent to the melting point of the lubricant powder (zinc stearate) (for example, 120 ° C) until the intermediate green compact 110 is received (Cavity 42)) is warmed (warmed up). The temperature of the intermediate-pressure powder 110 after the temperature increase can be received without falling. As a result, the lubrication action can be secured while preventing the resolidification of the dissolved (liquefied) lubricant first.

In the present embodiment, the second warming-up device 47 is an electric heating method (heater). However, the second warming-up device 47 can also be implemented by a circulating heating device that warms up by circulating warm oil or hot water.

In this sense, the second warming device 47 can be heated until the finished green compact 120 is press-formed. This makes it possible to further enhance the fluidity of the dissolved lubricant in the entire direction in the press-molding, so that the friction resistance between the particles and the second metal mold (lower mold 41 (cavity 42) And can be greatly reduced.

In this regard, in the present embodiment, an unillustrated warming function for warming the first mold (lower mold 21) is provided. However, the high-density molding process of the present invention can be carried out without heating the first mold (the lower mold 21) before the heating process for heating to raise the temperature of the intermediate-pressure powder 110.

However, when the composition of the mixed powder or the shape of the intermediate green compact 110 is unusual, the intermediate green compact 110 has a large heat capacity, the large heating / heating unit 30 is not provided, There is a fear that the heating temperature of the intermediate green compact 110 is increased for a long time. In such a case, it is preferable to warm the first mold (lower mold 21). For this reason, in the present embodiment, the first mold is heated.

That is, a first warming device (not shown) capable of changing the set temperature is also provided in the first mold (the lower mold 21 (cavity 22)), so that after the end of the molding of the intermediate green compact 110, The first mold (lower mold 21) is heated to deliver the lubricant powder so as to be preheated before being delivered to the warmer 30. By doing so, the heating and heating time can be reduced, and the production cycle can be shortened.

The relationship between the pressing force P (the second pressing force P2) in the second press molding machine 40 and the density? Of the finished green compact 120 obtained corresponding thereto will be described with reference to FIG.

The density p obtained by the second press molding machine 40 is in accordance with the characteristic B. [ That is, unlike the case (characteristic A) in the first press molding machine 20, the density? Does not increase gradually as the second pressing force P2 is increased. That is, the density p does not increase until the final first pressing force P1 (for example, the transverse index 75 or 85) in the first press-molding step is exceeded. When the second pressing force P2 exceeds the final first pressing force P1, the density r becomes high at a time. It is understood that the second press-molding is to continuously carry out the first press-molding continuously.

As described above, it is not necessary to perform the operation in which the first pressing force P1 is raised to a value (transverse index 100) corresponding to the maximum capacity at any time in the first press-molding step. That is, unnecessary time and energy consumption when the first press forming is continued after the compression limit can be eliminated. Leading to reduced manufacturing costs. In addition, overload operation exceeding the transverse index of 100 is easy to avoid, so there is no fear of breakage of the mold. It is easy to operate and handle as a whole, and safe and stable operation is possible.

The workpiece conveying device 50 is constructed so that the intermediate green compact 110 drawn out from the first mold (lower mold 21) by the first drawing device (the movable member 23 and the through hole 24) (Movable member 43, second movable member 43, second movable member 43, second movable member 43, and second movable member 43) (For example, the discharge shooter 59) for discharging the finished green compact 120 drawn out from the second mold by the through hole 44 (through hole 44) to the outside of the high-density molding apparatus 1. [

The workpiece conveying device 50 is disposed between the first press molding machine 20 and the heating and warming unit 30 and between the heating and warming unit 30 and the second press molding machine 40 and between the second press molding machine 40 ) To the discharging shooter 59, as shown in Fig.

The workpiece conveying device 50 of the present embodiment is composed of three conveying bars 51, 52 and 53 for synchronous operation shown in FIG. 3 (B). The transfer bars 51, 52 and 53 move from the inside of the paper surface of Fig. 3 (A) to the transfer line of Fig. 3 (B) at the front and move to the original position after moving from left to right I am. (Intermediate bar graphite powder 110) is heated to a temperature corresponding to the melting point of the mixed powder pressurized intermediate medium (intermediate bar graphite powder 110), and the setting device (transfer bar 52, movable member 43 and through hole 44) (Lower mold 41 (cavity 42)).

The workpiece transfer device may include a finger or the like which is driven in a two-dimensional or three-dimensional direction, and may be formed by a transfer device for sequentially transferring workpieces to each of the molds.

It should be noted, however, that the compression characteristics are unique with regard to the introduction of technology for aggressively liquefying the lubricant in the intermediate process. That is, as shown in Fig. 4, the compression of the intermediate-pressure powder 110, which is performed by applying the first pressing force P1 under the granular lubricant, depends on the steep rise and then the characteristic A which becomes gentle. On the other hand, the compression of the finished green compact 120, which is performed by applying the second pressing force P2 under the liquid lubricant, rises suddenly (suddenly) when the first pressing force P1 is exceeded, According to characteristic B

Significant technical features are inherent here. In order to shorten the total production cycle of the intermediate green compact forming process (PR2) and the finished green compact forming process (PR5), it is necessary to increase the true density ratio in the intermediate green compact forming process (PR2) (PR5) which follows the constant characteristic B after abruptly increasing the pressure to a certain extent. According to this idea, if the molding time is long for a gentle characteristic, it may result in regretting that the wasted time is wasted. In addition, there is a risk of causing damage to the mold.

Therefore, paying attention to the steep characteristic of the gentle characteristic A and the subsequent sharp characteristic B after the steep state, even if the true density ratio in the intermediate-pressure powder forming process PR2 is suppressed to a low level, the process is immediately terminated, And to the powder molding process PR5. According to this idea, it is possible to minimize the meaningless time.

However, these unique characteristics A and B have a sense of lack of awareness even among those skilled in the art. In addition, the selection setting of the transition from the characteristic A to the characteristic B at what timing in the manufacturing practice belongs to the operator's whole-body and arbitrary operation. Therefore, there is a case where the switching timing is quickly selected from the idea of rapidly terminating the intermediate-pressure powder forming process PR2. In other words, when the selection is made to advance to the finished green compact immediately after the compression degree is appropriately advanced, the following problems may occur in the finished green compact forming process (PR5).

That is, when the compression ratio (density ratio) of the intermediate green compact 110 is low, the compression ratio in the green compact forming process PR5 must be relatively large. This means that the lowering stroke of the slide required for forming the finished green compact is increased. The relative movement amount (pressure contact sliding distance) between the outer peripheral surface of the intermediate green compact 110 and the inner wall surface of the cavity 42 of the second mold in the vertical direction increases by an amount corresponding to the enlargement of the slide stroke. The frictional resistance between them increases in proportion to the increase of the relative movement amount. That is, not only does it cause an overload state, but also there is a risk of damaging the mold.

According to a number of commercialization tests and studies by the applicant, the kind of the base metal powder, the kind and amount of the lubricant, the value of the gap in the radial direction at the time of putting the second die (lower mold 41) Parameters were taken into account. As a result, in the case where the highest density of the intermediate powder compacts (intermediate powder compacts) 110 that can be formed by applying the first pressing force P1 is 100% It was verified that if the first pressing force P1 is applied to the powder to compress the density ratio to 85% or more, the problem does not occur.

In other words, apart from the fact that the swelling phenomenon can be exhibited up to a density ratio of 80%, in order to avoid an overload state or breakage of the mold during the second press forming process, the first press molding process is terminated at a density ratio of less than 85% Do not use early timing switching. If the density ratio is 85% or more, the problem does not occur. However, from the viewpoint that the object is to avoid mold breakage, it is preferable that the upper limit side is 96% or less of the density ratio. This density ratio 96% is not a limit value but a threshold value, so it may be selected to be less than 100%. In any event, the intermediate green compact 110 having a density ratio of less than 85% should not be handed over to the second press forming process.

In the high-density molding apparatus for mixed powder according to the present embodiment, the high-density molding method is carried out by the following steps.

(Procurement of mixed powder)

The mixed powder (100) in which the base metal powder (glassy insulating coating coat iron powder for magnetic core) and the lubricant powder (zinc stearate powder) of 0.2 wt% are mixed and transported smoothly is procured. And supplied to the mixed powder feeder 10 by a predetermined amount (process PR0 in Fig. 1).

(Filling of mixed powder)

The mixed powder feeder 10 is moved from a predetermined position (solid line) to a replenishment position (dotted line) as shown in Fig. 3 (B) at a predetermined timing. The supply port of the mixed powder feeder 10 is then opened and a predetermined amount of mixed powder 100 is charged into the lower mold 21 (cavity 22) of the first press molding machine 20 Process PR1). For example, it can be charged in 2 seconds. After the filling, the supply port is closed, and the mixed powder feeder 10 returns to a predetermined position (solid line).

(Molding of intermediate green powder)

The upper mold 25 of the first press-molding machine 20 is lowered together with the slide 5 of Fig. 2 to form the first pressurizing force P1 for pressurizing the mixed powder 100 in the lower mold 21 (cavity 22) 1 pressure forming process is started. The solid lubricant has a sufficient lubricating action. The density p of the compressed intermediate green compact 110 increases according to the characteristic A of Fig. In the present embodiment, the first pressure forming process is terminated when the first pressing force P1 reaches a pressure (3.0 Ton / cm2) corresponding to a transverse index (for example, 30). The transverse index 30 has a true density ratio of 85%, and the density rho is increased to 6.63 g / cm 3 (corresponding to a longitudinal axis index of 87). For example, when the press molding is completed for 8 seconds, the intermediate green compact 110 is molded in the mold (lower mold 21) as shown in Fig. 3 (A) (step PR2 in Fig. 1).

Thereafter, the upper die 25 is raised by the slide 5. Further, in the second press molding machine 40, the second press forming process related to the intermediate green compact 110 is synchronized.

(Withdrawal of intermediate-pressure powder)

The first take-out device (movable member 23) operates and the intermediate green compact 110 is pushed up to the transport level HL. That is, the lower mold 21. 3 (B), the workpiece conveying device 50 is operated, and the intermediate barrel powder 110 is conveyed toward the heating / warming-up device 30 by the conveying bar 51. At this stage, the movable member 23 is returned to the lower initial position. The intermediate green compact 110 after the transfer is positioned on the support member 32 in the form of a wire net as shown in Fig. 3 (A).

(Heating up temperature)

In Fig. 3 (A), the heating / warming-up unit 30 is started. Warm air is sprayed from the spray hood 31 and the intermediate-pressure powder 110 is heated to a temperature equivalent to the melting point of the lubricant powder (for example, 120 DEG C) (process PR3 in Fig. 1). That is, the lubricant is dissolved and the lubricant distribution in the intermediate-compact powder 110 is uniformly changed by the flow. The heating temperature rise time is, for example, 8 to 10 seconds. The warm air is recirculated through the support member 32 in the form of a wire net and the exhaust circulation hood 33.

(Set of intermediate-pressure powder whose temperature has been raised)

3 (B), the heated intermediate-pressure powder 110 is conveyed to the second press-molding machine 40 by the workpiece conveying device 50 (conveying bar 52) and is conveyed to the upper side of the lower mold 41 And is set on the movable member 43 in the lower mold 41 (cavity 42) (process PR4 in Fig. 1).

(Warming of mold)

And the second warming-up device 47 operates when it is selected as the start in the second press molding machine 40. The mold (lower mold 41 (cavity 42)) is warmed to the melting point equivalent temperature (120 占 폚) of the lubricant powder before the intermediate green compact 110 is received (set).

It is possible to prevent the re-solidification of the lubricant in the intermediate pressure-applied powder 110 that has been received after that.

(Molding of the finished green compact)

The upper die 45 is lowered as shown in Fig. 3 (A) together with the slide 5 of Fig. 2 and the intermediate pressurized powder 110 in the lower die 41 (cavity 42) It begins to pressurize. The lubricant in the liquid phase has sufficient lubricating action. The density p of the compressed intermediate green compact 110 increases according to the characteristic B of Fig. That is, when the second pressing force P2 exceeds the abscissa (for example, 30 ... the pressing force 3.0 Ton / cm2), the density ρ corresponding to the true density ratio 85% ρ (7.75 g / cm 3). When the second pressing force P2 is increased to a transverse index of 100 (10 Ton / cm2), the density rho (7.75 g / cm3) becomes uniform as a whole. At this time, since the required slide stroke (relative movement amount) is short, there is no fear of overload state or breakage of the mold. However, due to the sweating phenomenon in which the lubricant flows out in all directions as the press molding progresses, the frictional resistance of the particles and the mold can be effectively reduced not only between the base metal particles. For example, after completion of the second press forming process for 8 seconds, the finished green compact 120 is formed in the second mold (lower mold 41) (step PR5 in Fig. 1). Thereafter, the upper die 45 is lifted by the slide 5. In the first press-molding machine 20, the first press-forming process for the intermediate intermediate green compact 110 is performed in synchronization with each other.

(Product withdrawal)

The second drawing device (movable member 43) operates and the finished green compact 120 is pushed up to the transfer level HL. In other words, it is drawn out from the lower die 41. 3 (B), the workpiece conveying device 50 operates, and the finished green compact 120 is conveyed toward the discharge shooter 59 by the conveying bar 53. Then, At this stage, the movable member 43 is returned to the initial position of the lower portion. The finished green compact 120 having the density rho (7.75 g / cm3) corresponding to the longitudinal axis index 102 does not change or dissolve the vitreous because the lubricant powder has a low melting point. Therefore, it is understood that a high-quality magnetic powder for a magnetic core capable of reducing eddy current loss and increasing magnetic flux density can be efficiently produced.

(Manufacturing cycle)

According to the high density forming method according to each of the above processes, the first press forming process, the heating temperature raising process, and the second press forming process can be executed in synchronism with the metallic powder (mixed powder 100) Density green compact (finished green compact 120) can be manufactured at a cycle time of 12 to 14 seconds by adding a work transfer time (for example, 2 to 4 seconds) to a heating temperature raising treatment time (for example, 10 seconds) .

It can be understood that the manufacturing and production time can be dramatically improved even when compared with the high-temperature sintering treatment time of 30 minutes or more in the conventional example. For example, it is possible to stabilize the supply of parts for automobiles, which are compact and light in weight, have a complicated shape, and have high mechanical strength, and components for electromagnetic machines having excellent magnetic characteristics and mechanical strength, and can contribute greatly to the reduction of production costs thereof.

Thus, according to the present embodiment, the metal powder (the lower mold 21) is filled with the mixed powder 100 in which the base metal powder is mixed with the lubricant powder having the low melting point, and the first pressing force P1 is applied to form the intermediate pressure The intermediate pressure powder 110 having a density ratio of 85 to 96% is formed by applying a first pressing force P1 to the mixed powder in the first mold when the maximum density of the powder is 100% The lower mold 110 is heated to positively raise the temperature to a temperature equivalent to the melting point of the lubricant powder (for example, 120 占 폚), the intermediate mold 110 having been heated is set in the second mold (lower mold 41) Density molding method for forming the finished green compact 120 by applying the second pressing force P2 in the mold (lower mold 41), the high-density green compact can be reliably and stably manufactured. In addition, it is possible to promote the shortening of the actual production cycle while securing the safety of the device (mold).

In addition, since the sintering process for a long time at a high temperature can be eliminated, the oxidation of the green compacts 110 and 120 can be greatly suppressed, and energy consumption can be minimized and manufacturing cost can be greatly reduced. We can also welcome global environmental conservation.

Further, since the melting point of the lubricant powder falls within the temperature range of 90 to 190 占 폚, it is possible to expand the selectivity of the lubricant.

Further, since the second mold (lower mold 41) is heated by the second warming device 47, the flowability of the dissolved lubricant in the second press molding can be further enhanced in all directions. That is, not only the base metal particles but also the frictional resistance between the particles and the second mold (lower mold 41) can be greatly reduced.

Since the second pressing force P2 can be set to the same value as the first pressing force P1, it is easy to carry out and handle the press-forming step, and indirectly contribute to further reduction of the manufacturing cost of the green compact, In the implementation, for example, it is possible to simply build a single press machine as a base.

Also, even if the base metal powder is changed from a glass-ceramics-coated-film-coated iron powder for magnetic core to an iron-based amorphous powder for magnetic core or an Fe-Si alloy powder for magnetic core, even if other conditions are the same, A magnetic core part having a corresponding excellent magnetic property can be manufactured efficiently and stably.

Although it was impossible to increase the density of the conventional apparatus (for example, the press machine) to the density corresponding to the longitudinal axis index 100 (transverse index 100 in FIG. 4), according to the present invention, . This fact is a breakthrough in the field of technology.

In addition, since the high-density molding apparatus 1 is composed of the mixed powder feeder 10, the first press-molding machine 20, the heating / warming-up machine 30 and the second press-molding machine 40, It can be carried out stably.

(Second Embodiment)

This embodiment is shown in Fig. The mixed powder feeder 10 and the first press molding machine 20 remain unchanged as compared with the case of the first embodiment and the heating and warming machine 30 and the second press molding machine 40 are integrally formed do.

That is, the high-density molding apparatus is formed by a heat press molding machine 70 in which the heating / warming-up unit 30 and the second press-molding machine 40 in the first embodiment are integrally combined with these functions. The heating press molding machine 70 is formed by a plurality of (two in this embodiment) heating and pressing forming magnets 70A and 70B and each of the heating and pressing forming magnets 70A and 70B is manufactured by a control device So that they can be selected and sequentially operated for each cycle.

Each of the heat press-molded magnets 70A and 70B has a basic structure corresponding to the second press molding machine 40 in the first embodiment. The respective heating and press forming magnets 70A and 70B are provided with a multifunctional heating device 70B having a complex function corresponding to the respective functions of the heating warmer 30 and the second warmer device 47 in the case of the first embodiment, (48).

That is, the multi-functional-type heating device 48 is of an electric heating type having a set temperature switching function. The lower die 41 can be preheated to a lubricant melting point equivalent temperature (for example, 120 DEG C) in advance (before the intermediate green compact 110 is received). After the intermediate green compact 110 is received, the amount of heat generated is greatly changed so that the entire intermediate green compact 110 can be heated to a temperature equivalent to the lubricant melting point equivalent temperature (for example, 120 ° C). It is also possible to selectively switch the heating zone. After the heating and heating is completed, the second heat molding process is performed as in the case of the second press molding machine 40 in the first embodiment. The multifunctional-type heating device 48 operates so that the temperature of the intermediate-pressure powder 110 can be maintained at a temperature equivalent to the lubricant melting point equivalent temperature (for example, 120 ° C) during the second heat-forming process.

As shown in FIG. 6, each of the heating and pressure forming magnets 20, 70A and 70B has an independent press machine structure, and each of the slides 5, 5A, Respectively, by the rotation control of the motor. That is, in the case where one (the other) of each of the heating and pressure forming magnets 70A and 70B performs the press forming operation, the other (one side) is preheating and the press forming operation is not performed. The same is true in the case where the heat press molding machine 70 is formed of three or more heat press-molded bodies in relation to the production cycle time.

In the apparatus of this embodiment, in the course of press molding of the third intermediate green compact 110 in the first press molding machine 20, one of the heating and pressing forming magnets 70A (or the heating and pressing forming magnets 70B) The intermediate green compact 110 is heated and heated at the same time and the first intermediate green compact 110 is pressed from the pressed green compact 70B (or the hot press compacted magnet 70A) ).

As described above, according to the present embodiment, it is preferable to construct the heat press molding machine 70 with a plurality of heat and pressure forming magnets 70A and 70B having the same structure. Therefore, compared with the case of the first embodiment, . The simplification of the manufacturing line can be promoted and the handling can be further facilitated.

The first press molding machine 20 and the hot press forming magnet 70A (or the hot press forming magnet 70B) or the first press molding machine 20 and the respective hot press forming magnets 70A and 70B are connected to a single press It is also possible to construct it as a machine structure.

1 High-density molding device
10 Mixed Powder Charger
20 First press molding machine
30 Heated Warmer
40 2nd press molding machine
47 Heating device
48 Multifunctional heating device
50 Workpiece transfer device
70 Heating press molding machine
70A, 70B Heat-press molding self
100 mixed powder
110 Medium-pressure powder (mixed powder medium compact)
120 Completed compact powder (complete powder mixture)

Claims (8)

A first metal mold is filled with a mixed powder obtained by mixing a base metal powder with a lubricant powder having a low melting point,
In the case where the maximum density of the intermediate powder mixture compact capable of being formed by applying the first pressing force is 100%, the first pressing force is applied to the mixed powder in the first mold so that the mixed powder having a density ratio of 85 to 96% A sieve is molded,
The mixed-powder intermediate compact drawn out from the first mold is heated to positively raise the temperature of the mixed-powder intermediate compact to a temperature corresponding to the melting point of the lubricant powder,
The heated mixed powder intermediate compact is set in a second mold,
And a second pressing force is applied to the mixed powder intermediate compact in the second mold to thereby form a high-density powder mixture finished compact. The method according to claim 1,
Wherein the lubricant powder has a melting point falling within a temperature range of 90 to 190 占 폚. The method according to claim 1 or 2,
Wherein the second metal mold is preheated to a temperature equivalent to the melting point before the mixing of the powdery intermediate compact. The method according to claim 1 or 2,
And the second pressing force is selected to have the same value as the first pressing force. A mixed powder feeder capable of supplying a mixed powder obtained by mixing a base metal powder with a lubricant powder having a low melting point,
A first press molding machine for applying a first pressing force to the mixed powder filled in the first mold by using the mixed powder feeder to mold the mixed powder intermediate compact,
A heating and temperature raising device for raising the temperature of the mixed powder intermediate compact drawn from the first mold to a temperature corresponding to the melting point of the lubricant powder,
And a second press-molding machine for applying a second pressing force to the mixed-powder intermediate pressurizing body set in the second mold and heating it to form a high-density mixed powder-finished pressurizing body,
When the first press molding machine applies the first pressing force and the highest density of the mixed powder compact is 100%, the first pressing force is applied to the mixed powder in the first mold so that the density ratio becomes 85% to 96 % By weight of the mixed powder. The method of claim 5,
The heating and raising unit and the second pressing unit are formed by a heating and pressing apparatus integrally including these functions, and the heating and pressing apparatus is formed by a plurality of heating and pressing forming apparatuses, Wherein the plurality of powder compacts are formed so as to be able to be sequentially operated at every cycle. The method of claim 5,
And a warming device for warming the second mold. The method of claim 5,
Wherein the mixed powder compact is fed to the heating and raising device and the mixed powder intermediate compacted in the heating and heating device is transferred to the second press molding device, And a workpiece transferring device for transferring the finished mixed powder compacted body formed in the pressure molding machine to the discharge portion.

Images