JP2006305574A - Multi-layered green compact forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of easily forming a multi-layered cylindrical green compact having the small thickness of an inner layer. <P>SOLUTION: By using a die device having inner upper and lower punches 3, 5 close to a core and outer upper and lower punches 2, 4 between an inner wall of a die and the inner punches, a first powder is filled in a cylindrical outer cavity 7a, the first powder is enclosed by the outer upper punched 4, and the powder is compressed by the outer lower punch 2 to form a preliminary green compact 8. Next, the core 6 and the inner lower punch 3 are lowered, a second powder is filled in the inner cavity 7b, then, the core 6 is elevated, and the second powder is remained in a cylindrical inner cavity 7c. Finally, the preliminary green compact 8 and the second powder in the cylindrical inner cavity 7c are compressed by the upper and lower punches 2, 3, 4, 5 to form a formed body 9. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming a multi-layer green compact. More specifically, for example, a second-layer sliding material made of a different material is integrally formed on the inner periphery of a cylindrical member, such as a multi-layer slide bearing. The present invention relates to a method capable of easily forming a multilayered green compact when producing a formed sintered product.

  As a method of forming a multi-layer green compact, a mold apparatus having a die, a core, and upper and lower punches divided into an inner part and an outer part is used, and a first cavity is formed by lowering only an outer lower punch. After filling the powder and closing the filled powder with the upper punch, the lower outer punch is raised to compress the powder, and then the inner lower cavity is lowered to fill the inner cavity formed with the second powder. Compressing the green compact of the first powder and the second powder in the inner cavity with the upper and lower punches to a predetermined length dimension, a powder molded body in which two layers are integrally formed There is a technique of extracting from a mold (for example, see Patent Document 1).

  Further, as a means for pre-compacting the first powder, after compressing the powder with the upper and outer punches and pushing up the first powder compact to make the upper surface of the first powder compact and the die surface the same. There is a technique for filling the inner cavity formed by lowering the inner lower punch with the second powder (for example, see Patent Document 2).

In the above conventional powder molding technology, when the gap between the inner cavities is narrow (the inner layer is thin), powder filling is difficult and the powder is flowable and can be filled appropriately. Thickness was necessary.
Japanese Examined Patent Publication No. 54-43963 (page 3) JP 52-2817 A (page 6)

  As described above, the present invention aims to solve a problem that has been difficult in the past, and is a multilayer cylindrical powder compact capable of forming a multilayer powder compact with a thinner inner member. A method for forming a body is provided.

The present invention has been made to solve the above problems, and is characterized by taking the following technical means. That is, according to the present invention, in the molding of a cylindrical green compact in which two layers of the inner side and the outer side are integrally formed, the die, the core, and the upper and lower punches are arranged in the inner and outer sides corresponding to the thickness of each layer of the green compact. The mold device is divided and provided with inner upper and lower punches closer to the core and with outer upper and lower punches between a die inner wall and the inner upper and lower punches, and is formed by relative elevation of each member of the mold device. This is a method for forming a multilayered cylindrical green compact, characterized in that the powder filling into the cavity and the compacting operation comprise the following steps (1) to (6).
(1) filling a first powder into a cylindrical outer cavity formed by the die hole, the outer periphery of the inner lower punch, and the end of the outer lower punch;
(2) a step of closing the first powder with an outer upper punch and compressing the powder with an outer lower punch to form a pre-compacted powder;
(3) Lowering the core and the inner lower punch, and filling the second powder into the inner cavity formed between the inner periphery of the preliminary green compact and the outer periphery of the outer lower punch,
(4) The core is raised to discharge the powder on the core, and the second powder remains in the cylindrical inner cavity formed between the inner periphery of the pre-compacted compact and the inner periphery of the outer lower punch and the core. Process,
(5) A step of compressing the pre-compacted powder and the second powder in the inner cavity of the cylinder with upper and lower punches to form a molded body,
(6) A step of pulling up the molded body from each of the lower punches by pushing it up.

In the second aspect of the present invention, in the molding of the cylindrical green compact in which the inner and outer two layers are integrally formed, the die, the core, and the upper and lower punches correspond to the thickness of each layer of the green compact. The mold apparatus is divided into two inside and outside, provided with inner upper and lower punches closer to the core, and provided with outer upper and lower punches between the inner wall of the die and the inner upper and lower punches. A method for forming a multi-layer cylindrical green compact, characterized in that powder filling and compacting operation into a cavity formed by ascending and descending comprises the following steps (a) to (f).
(A) filling the first powder into the cylindrical outer cavity formed by the die hole, the outer periphery of the inner lower punch, and the end of the outer lower punch;
(B) compressing the first powder with an outer punch to form a pre-compacted powder;
(C) Lowering the core and the inner lower punch, and putting the second powder into the flanged cavity formed between the inner periphery of the preliminary green compact, the upper portion of the preliminary green compact, and the inner periphery of the outer lower punch. Filling process,
(D) The core, the outer lower punch, and the preliminary compact are raised, the filled powder on the preliminary compact and the core are discharged, the inner periphery of the preliminary compact and the inner periphery of the outer lower punch and the core Leaving the second powder in a cylindrical inner cavity formed between
(E) a step of compressing the pre-compacted compact and the second powder in the cylinder inner cavity with the upper and lower punches to form a molded body;
(F) A step of pulling up the molded body from the lowering die by each lower punch.

  The difference between the first invention and the second invention is that the steps (2) to (4) in the steps of the first invention have been changed to the above (b) to (d), respectively.

  According to the present invention, after forming the outer pre-compacted powder, the core and the inner lower punch are lowered to form the second powder filling inlet widely, so that the powder can be uniformly filled to the bottom of the cavity. And then, by raising the core and discharging the second powder on the core to complete the filling of the second powder on the inner side, even if the inner member is thin, Powder filling can be easily performed, and a multilayer sintered product having a very thin sliding member on the inner peripheral surface can be easily manufactured.

  The best mode for carrying out the invention will be described below with reference to the drawings.

  Each drawing is exaggerated for easy understanding. The operation of the mold apparatus is described in a form in which the die does not move up and down, and shows the principle of molding by relative raising and lowering. Actually, it is desirable that the die is moved up and down using an NC control press.

  FIG. 1A to FIG. 1F are longitudinal sectional views showing the powder molding method of the present invention, which are divided into six characteristic steps. The molding die includes a die 1, a core 6 provided at the center, and upper and lower punches. The upper and lower punches are divided into two inside and outside corresponding to the thickness of each layer of the green compact. That is, the inner lower punch 3 and the inner upper punch 5 are provided on the core 6 side, and the outer lower punch 2 and the outer upper punch 4 are provided on the outer side.

  In FIG. 1A, the upper surfaces of the die 1, the inner lower punch 3 and the core 6 are the same surface, and the outer lower punch 2 is lowered to fill the cylindrical outer cavity 7a with the first powder by the feeder 10. It shows the state. Thereafter, when the feeder 10 moves away from the cavity, the upper surface of the powder is scraped off.

  FIG. 1B shows a state in which the outer upper punch 4 and the inner upper punch 5 are lowered to close the filling powder, and the outer lower punch 2 is raised to compress the powder to form the preliminary green compact 8.

  In FIG. 1C, the outer upper punch 4 and the inner upper punch 5 are raised, and the core 6 and the inner lower punch 3 are lowered to form a columnar inner cavity 7b. 7b shows a state in which the second powder is filled.

  FIG. 1 (d) shows a state in which only the core 6 is raised and the second powder on the core 6 is pushed up into the feeder 10. As a result, the second powder remains in the cylindrical inner cavity 7c.

  FIG. 1 (e) shows a state in which the preliminary compact 8 is compressed with the upper and lower outer punches, the second powder in the cylindrical cavity 7 c is compressed with the upper and lower inner punches, and the compact 9 is compacted. ing.

  FIG. 1 (f) shows a state in which the molded body 9 is pushed up by the inner and outer lower punches and extracted from the die 1.

  The green compact 9 in which the outer member 9a and the inner member 9b are integrally formed is obtained by the above process.

  2 (a) to 2 (f) are longitudinal sectional views showing the powder molding method according to the second invention of the present invention in which some steps are different from the above.

  The mold structure is the same as that described above, but the steps shown in FIGS. 1B, 1C, and 1D are different from those described above. A press machine that is activated is used.

  FIG. 2A is the same as FIG. 1A, and shows a state in which the cylindrical outer cavity 7a is filled with the first powder.

  FIG. 2B shows a state in which the first powder is compressed to form the pre-compacted powder 8, but the point different from FIG. 1B is that the powder is compressed by the outer upper punch 4. That is. In this case, there is a form of compression by the outer lower punch 2.

  FIG. 2 (c) shows that the lowering of the core 6 and the inner lower punch 3 is the same as that of FIG. 1 (c), but above the preliminary green compact 8 formed in the state of FIG. 2 (b). This is different from FIG. 1 (c) in that a flanged cavity 7d is formed as a whole and the second powder is filled therein.

  2D, the outer lower punch 2 is raised, the upper surface of the preliminary green compact 8 is made the same as the upper surface of the die 1, and the second powder existing on the preliminary green compact 8 is pushed up to the feeder 10. FIG. At the same time, the point that the core 6 is raised to push the second powder above the core 6 to the feeder 10 is different from FIG. As a result, as in FIG. 1D, the in-cylinder cavity 7c is filled with the second powder.

  2 (e) and 2 (f) are the same as FIG. 1 (e) and FIG. 1 (f). The molded body 9 is modeled by the inner and outer upper and lower punches, and the molded molded body 9 is extracted from the mold.

  In these molding methods, in the steps shown in FIGS. 1C to 1D and FIGS. 2C to 2D, the in-cylinder cavity 7c around the core 6 is filled with the second powder. Therefore, when the core 6 is lifted and the second powder that is above the core 6 is pushed up to the feeder 10 with the inner lower punch 3 located below, the following (A), (B), or (C ), The powder filling of the thinner inner layer can be reliably and stably performed.

  (A) The front edge of the core 6 is chamfered small. If it does in this way, when raising the core 6, it will raise so that the 2nd powder with which it fills may be scraped off by a chamfering part, Therefore The 2nd powder can remain in the cylinder cavity 7c.

  (B) The density of the preliminary green compact 8 is set so as not to break and low in density. The low density increases the surface roughness, increases the friction with the second powder, and when the second powder rises due to the rise of the core 6, the second powder in the cylinder cavity 7c is also scraped together. The second powder can be left in the in-cylinder cavity 7e.

  (C) When filling the powder formed into the cavity formed by the core 10 being lowered by the feeder 10, the properties of the powder are improved so as to increase the apparent density of the filled powder, or vibration filling, Alternatively, measures such as increasing the amount of powder in the feeder should be taken. When the density of the filled second powder is high, the friction between the pre-compacted powder 8 and the inner walls of the outer lower punch 2 and the second powder increases, and the filling powder above the core 6 is smoothly sheared and raised. .

  It is also effective to repeatedly move up and down when raising the core 6. The repeated vertical movement may be vertical vibration. Since the second powder is intermittently sheared by the up and down operation, the second powder can be left in the in-cylinder cavity 7c.

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Explanation of symbols

1 Die 2 Outer Lower Punch 3 Inner Lower Punch 4 Outer Upper Punch 5 Inner Upper Punch 6 Core 7a Cylindrical Outer Cavity 7b Inner Cavity 7c Cylindrical Inner Cavity 7d Flange Inner Cavity 8 Preliminary Powder 9 Molded Body 9a Outer Member 9b Inner Member 10 Feeder

Claims (2)

In the molding of a cylindrical green compact in which the inner and outer layers are integrally formed, the die, core, and upper and lower punches are divided into two inward and outer according to the thickness of each layer of the green compact, and close to the core. Filling the cavity with powder formed by relative elevation of each member of the mold apparatus using a mold apparatus having an inner vertical punch and an outer vertical punch between the inner wall of the die and the inner vertical punch, and A method for forming a multilayer cylindrical powder compact, wherein the powder compaction operation comprises the following steps.
(1) filling a first powder into a cylindrical outer cavity formed by the die hole, the outer periphery of the inner lower punch, and the end of the outer lower punch;
(2) a step of closing the first powder with an outer upper punch and compressing the powder with an outer lower punch to form a pre-compacted powder;
(3) Lowering the core and the inner lower punch, and filling the second powder into the inner cavity formed between the inner periphery of the preliminary green compact and the outer periphery of the outer lower punch,
(4) The core is raised to discharge the powder on the core, and the second powder remains in the cylindrical inner cavity formed between the inner periphery of the pre-compacted compact and the inner periphery of the outer lower punch and the core. Process,
(5) a step of compressing the pre-compacted powder and the second powder in the cylinder inner cavity with upper and lower punches to form a molded body;
(6) A step of pulling up the molded body from the lowering die by each lower punch. In the molding of a cylindrical green compact in which the inner and outer layers are integrally formed, the die, core, and upper and lower punches are divided into two inward and outer according to the thickness of each layer of the green compact, and close to the core. Powder filling into a cavity formed by relative elevation of each member of the mold apparatus using a mold apparatus having an inner vertical punch and an outer vertical punch between a die inner wall and the inner vertical punch And a method for forming a multilayer cylindrical powder compact, wherein the compacting operation comprises the following steps.
(A) filling the first powder into the cylindrical outer cavity formed by the die hole, the outer periphery of the inner lower punch, and the end of the outer lower punch;
(B) compressing the first powder with an outer punch to form a pre-compacted powder;
(C) Lowering the core and the inner lower punch, and putting the second powder into the flanged cavity formed between the inner periphery of the preliminary green compact, the upper portion of the preliminary green compact, and the inner periphery of the outer lower punch. Filling process,
(D) The core, the outer lower punch, and the preliminary compact are raised, the filled powder on the preliminary compact and the core are discharged, the inner periphery of the preliminary compact and the inner periphery of the outer lower punch and the core Leaving the second powder in a cylindrical inner cavity formed between
(E) a step of compressing the pre-compacted compact and the second powder in the cylinder inner cavity with the upper and lower punches to form a molded body;
(F) A step of pulling up the molded body from the lowering die by each lower punch.

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