JP2015205324A - Molding apparatus and molding method of green compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the efficient molding of a green compact formed by laminating a plurality of compression molding layers in a radial direction.SOLUTION: A molding apparatus 10 for molding a green compact formed by laminating first and second compression molding layers in a radial direction comprises: a cylindrical die 12 forming a cavity in the inner periphery; a molding die 11 having a pair of an upper punch 13 and a lower punch 14 which move up and down relatively to the cavity; and a powder filling unit 20 for filling the cavity with first and second powders M1, M2 formed in each compression molding layer. The powder filling unit 20 comprises a partition member 22 which is provided in the cavity in an insertable/removable way, and can fill the cavity with the first and second powders M1, M2 when inserted into the cavity in a state of separating the powders from each other in a radial direction of the green compact to be molded.

Description

  The present invention relates to a green compact molding apparatus and molding method.

  Patent Document 1 below discloses a technical means for forming a green compact having a two-layer structure in which materials (metal compositions) are different between an outer diameter side and an inner diameter side. More specifically, a cylindrical die that molds the outer diameter surface of the green compact, a core that molds the inner diameter surface of the green compact, a cylindrical upper punch that moves up and down relative to the die, There is disclosed a molding apparatus that includes a first punch and a second lower punch, each having a punch and a partition member, each of which can be moved up and down independently. When such a molding apparatus is used, for example, a green compact having a two-layer structure is molded as follows.

  First, the partition member and the second lower punch disposed on the inner diameter side thereof are disposed at the raised position, and the first lower punch disposed on the outer diameter side of the partition member is disposed at the lowered position. A first space (cavity) is formed on the outer diameter side of the member, and the first powder loaded in the first shoe box is filled in the first space. Next, a second space is formed on the inner diameter side of the partition member by lowering the second lower punch, and the second powder charged in the second shoe box is filled in the second space. Then, after the partition member is lowered, the upper punch is lowered, and the first and second powders are simultaneously compressed in the axial direction. Thereby, for example, a green compact having a two-layer structure in which the outer diameter side is composed of a high-strength first powder compression molding layer and the inner diameter side is composed of a second powder compression molding layer having excellent wear resistance is obtained. Therefore, if this green compact is sintered, it is possible to obtain sintered metal mechanical parts (for example, bearings and gears) having high strength on the outer diameter side and excellent wear resistance on the inner diameter surface. In short, if the technical means of Patent Document 1 is adopted, sintered metal parts having different characteristics for each region in the radial direction can be easily obtained.

  Patent Document 1 employs the first and second partition members that can be moved up and down independently, and the first to third lower punches that can be moved up and down independently, thereby providing three compressions. It is also described that a green compact having a three-layer structure in which molding layers are laminated in the radial direction is molded. More specifically, by arranging both the partition members and the second and third lower punches in the raised position and arranging the first lower punch in the lowered position, a first space formed between the die and the first partition member is formed. By filling the first powder and then filling the second space formed between the partition members by moving the second lower punch downward, and then moving the third lower punch downward A third space formed between the second partition member and the core is filled with the third powder. Then, after lowering both partition members, the upper punch is lowered, and the first to third powders are simultaneously compressed in the axial direction, whereby a three-layered green compact is formed.

  In addition, the technical means of patent document 1 is theoretically applicable also when shape | molding the green compact formed by laminating | stacking four or more compression molding layers to radial direction.

JP 2005-95979 A

  The technical means disclosed in Patent Document 1 is useful for making it possible to manufacture a multi-layered green compact, and in turn, a machine part that can simultaneously satisfy different required characteristics for each region in the radial direction at a relatively low cost and with high accuracy. is there. However, since the cavity is formed in stages and filled with each raw material powder, there are problems that the cycle time becomes long and the structure and operation control of the molding die become complicated.

  In view of such circumstances, an object of the present invention is to enable a compact green compact formed by laminating a plurality of compression-molded layers in the radial direction efficiently and at low cost, through which various demands are made. An object of the present invention is to make it possible to manufacture a sintered metal part that can satisfy the characteristics at a low cost.

  The present invention devised to solve the above problems is a molding apparatus for molding a green compact formed by laminating a plurality of compression molding layers in the radial direction, and a cylinder that forms a cavity on the inner periphery , A molding die having a pair of upper and lower punches that move up and down relatively with respect to the cavity, and a powder that fills the cavity with a plurality of types of raw material powders each molded into each compression molding layer The powder filling unit is provided so as to be insertable into and removable from the cavity. When the powder filling unit is inserted into the cavity, a plurality of types of raw material powders are separated from each other in the radial direction of the green compact. A partition member that can be filled is provided. Note that the “diameter direction of the green compact” in the present invention is strictly “the radial direction of the green compact to be molded” (the same applies hereinafter).

  In the case of the molding apparatus having the above-described configuration, when molding a green compact formed by laminating a plurality of compression molding layers in the radial direction, a plurality of types of raw material powders molded into each compression molding layer are used. The cavities of the molding dies can be filled at the same time in a state of being separated from each other in the radial direction, and then the mutual separation state can be released, and then a plurality of kinds of raw material powders can be compressed at the same time. In addition, strictly speaking, the “mutually separated state” herein is “a state in which plural kinds of raw material powders are separated from each other in the radial direction” (the same applies hereinafter).

  That is, according to the above molding apparatus (and molding method), (1) a partition member provided in a single powder filling unit loaded with a plurality of types of raw material powders is inserted into a cavity (arranged in the cavity), In this state, a plurality of raw material powders are simultaneously filled in the cavity from the powder filling unit, and then (2) the partition member disposed in the cavity is removed from the cavity. The cavity can be filled in a state of being laminated in the radial direction of the green compact to be molded. In short, according to the present invention, when filling a cavity with a plurality of kinds of raw material powders laminated in the radial direction, a plurality of shoeboxes (corresponding to powder filling units) are stepwise like conventional techniques. Fill the cavity with raw material powder step by step, or use a molding die with multiple lower punches and partition members each moving up and down independently, and step by step multiple lower punches and partition members It is no longer necessary to operate. Therefore, the time required from the start of operation of the molding apparatus to the completion of powder filling into the cavity, and hence the compact molding cycle time can be greatly reduced, and the molding apparatus can be simplified and made compact as a whole. Can do. Therefore, according to the present invention, a green compact having a multilayer structure formed by laminating a plurality of compression molding layers in the radial direction can be efficiently molded at a low cost.

  In the above molding method, after the plural kinds of raw material powders are arranged in a state of being separated from each other in the radial direction outside the molding die in which the cavities are not formed, the molding die can be moved while maintaining the mutual separation state. By relatively moving the side and the stationary side, the formation of the cavity and the simultaneous filling of a plurality of types of raw material powders into the cavity can proceed simultaneously. In this way, the raw material powder can be filled into the cavity smoothly and efficiently.

  It is preferable that the above operation for releasing the mutual separation state is performed in a state in which at least one raw material powder can be replenished in the cavity among a plurality of types of raw material powders (to be filled in the cavity). This is because the space formed in the cavity is filled with the raw material powder along with the releasing operation of the mutual separation state (with the partition member being detached from the cavity), and a green compact with a predetermined density can be formed.

  In the molding apparatus having the above configuration, a molding die having a core that is disposed on the inner periphery of the die and that molds the inner diameter surface of the green compact may be employed. In this way, a cylindrical green compact can be formed.

  In the molding apparatus configured as described above, the powder filling unit moves (transfers) between a filling position where a plurality of kinds of raw material powders can be filled in the cavity and a retracted position spaced apart from the cavity in the radial direction. Can be configured. Thereby, the apparatus failure accompanying interference with a powder filling unit and an upper punch can be prevented reliably.

  By the way, in the molding apparatus having the above configuration, the powder filling unit interferes with the upper punch when the cavity is filled with a plurality of types of raw material powder from the powder filling unit (when the powder filling unit is located at the filling position). Therefore, it is necessary to ensure a sufficient vertical separation distance between the upper surface of the die and the lower surface of the upper punch during the powder filling process. However, after the powder filling process is completed, the upper punch is moved relatively closer to the lower punch, and the powder compression process is performed in which the raw material powder filled in the cavity is compressed by the upper punch and the lower punch. Therefore, if the above-mentioned vertical separation distance is too large during the powder filling process, the upper punch can be moved up and down (applying downward pressure to the upper punch) as a press unit. It is necessary to use a large press unit with a large stroke amount.

  Therefore, as the above-described molding apparatus, a device further having an elevating unit that holds the upper punch so as to be able to move up and down is used, and in this elevating unit, the raw powder in the cavity is compressed between the upper punch and the lower punch A movable spacer that moves (transfers) to each other between a pressurizing position where pressure can be applied and a position where pressure cannot be applied to the upper punch is provided, and the movable spacer is moved downward. Along with this, the pressure is moved from the pressure impossible position to the pressure pressure position, and the upper punch moves upward to move from the pressure position to the pressure impossible position.

  In this way, by selecting and using a movable spacer having an appropriate vertical dimension, during the powder filling process, the upper and lower parts do not interfere with the upper punch and the powder filling unit between the die and the upper punch. While a directional separation distance (a large space) can be secured, the stroke amount in the vertical direction of the upper punch, which is necessary when executing the powder compression process, can be reduced. Therefore, it is possible to avoid an unnecessarily large size of the press unit for pressing the upper punch downward, and thus the molding apparatus.

  The movable spacer can move between the pressurizing position and the non-pressurizable position by moving forward and backward in the radial direction of the green compact. If it does in this way, the thing of simple structures, such as an air cylinder, can be adopted as a drive mechanism for moving a movable spacer between the above-mentioned two positions.

  The elevating unit may further be provided with a guide member for guiding the mutual movement of the movable spacer between the two positions. In this way, the movable spacer can be accurately guided and moved to a predetermined pressure position, so that the raw material powder filled in the cavity can be appropriately compressed.

  As described above, according to the present invention, a green compact having a multilayer structure formed by laminating a plurality of compression molding layers in the radial direction can be efficiently molded at low cost.

It is an example of the sintered metal part formed by sintering the green compact shape | molded with the shaping | molding method which concerns on this invention, (a) A figure and (b) figure are respectively the longitudinal cross-sectional view of the sintered metal part, It is a cross-sectional view. It is a front view including the partial cross section of the compacting device concerning the embodiment of the present invention, and is a figure showing the initial state of the compacting device. In said shaping | molding apparatus, it is a figure which shows the state which the powder filling unit moved to the filling position. In said shaping | molding apparatus, it is a figure which shows the state with which the raw material powder is filled into the cavity. It is a figure which shows the state which the powder filling to the cavity was completed in said shaping | molding apparatus. In said shaping | molding apparatus, it is a figure which shows the state which the powder filling unit moved to the retracted position after completion of the powder filling to a cavity. It is a top view when said shaping | molding apparatus is seen from the arrow Y direction shown in FIG. In said shaping | molding apparatus, it is a figure which shows the state immediately after the compression process of raw material powder was started. It is a figure which shows the state which the compression process of the raw material powder advanced to some extent in said shaping | molding apparatus. In said shaping | molding apparatus, it is a figure which shows the compression state of raw material powder.

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

  FIG. 1A and FIG. 1B respectively show a longitudinal sectional view and a transverse sectional view of a sintered bearing 1 which is a kind of sintered metal part (a machine part made of sintered metal). The sintered bearing 1 shown in the figure is suitable for use in a joint portion that rotatably connects arms of a construction machine such as a hydraulic excavator or a bulldozer, and is disposed on the inner diameter side, and has an inner diameter surface 2a. A cylindrical bearing layer 2 having a bearing surface A on the outside and a cylindrical base layer 3 disposed on the outer diameter side and having a mounting surface B for an attached member (arm) (not shown) on the outer diameter surface 3a are in contact with each other. In a single state.

  The internal pores of the sintered bearing 1 can be impregnated with a lubricant such as lubricating oil. Thereby, the wear of the bearing surface A is suppressed or prevented. The oil content of the entire sintered bearing 1 is, for example, 10 to 25 vol%, preferably 15 to 25 vol%. If the oil content is less than 10 vol%, the desired lubrication characteristics cannot be stably maintained and exhibited over a long period of time. If the oil content exceeds 25 vol%, the internal porosity increases, so sintering. There is a possibility that the mechanical strength required for the bearing 1 cannot be ensured.

  The sintered bearing 1 described above has a different metal composition between the bearing layer 2 on the inner diameter side and the base layer 3 on the outer diameter side. The bearing layer 2 includes, for example, 10 to 30% by mass of copper from the viewpoint of improving the sliding characteristics of the bearing surface A provided on the inner diameter surface 2a, and most of the remainder is made of iron. On the other hand, since the base layer 3 having the attachment surface B for the attached member on the outer diameter surface 3a needs to have high mechanical strength, most of it is made of iron.

  The sintered bearing 1 having the above configuration mainly includes a compression molding process for obtaining a green compact 1 ′ (see FIG. 10), and a sintering process for obtaining a sintered body by sintering the green compact 1 ′. In addition, it is manufactured through an oil impregnation step in which the internal pores of the sintered body are impregnated with a lubricant such as lubricating oil. Hereinafter, embodiments of each process will be described in detail with a focus on the compression molding process to which the technical means according to the present invention is applied.

  The compression molding process is a process of obtaining a cylindrical green compact 1 ′ (see FIG. 10) that generally corresponds to the shape of the sintered bearing 1. More specifically, each of the compression molding processes is performed through the sintering process. This is a step of obtaining a green compact 1 ′ integrally including first and second compression-molded layers 2 ′ and 3 ′ to be a cylindrical bearing layer 2 and a base layer 3. The green compact 1 ′ is obtained by simultaneously compressing the first powder M1 molded into the first compression molding layer 2 ′ and the second powder M2 molded into the second compression molding layer 3 ′. . Hereinafter, this compression molding step will be described with reference to the drawings (FIGS. 2 to 10).

  First, the outline | summary of the shaping | molding apparatus 10 used at a compression molding process is demonstrated based on FIG.2, FIG.3 and FIG.6. The molding apparatus 10 mainly includes a molding die 11, a powder filling unit 20, an elevation unit 30 that holds the upper punch 13 of the molding die 11 so as to be movable up and down, and an elevation unit 30 (upper punch 13) that moves up and down. And a press unit (not shown).

  The molding die 11 is disposed on the inner periphery of the die 11 having a cylindrical die 11 (forming the outer diameter surface of the green compact 1 ′) forming a cavity 16 (see FIG. 4 and the like) on the inner periphery. The core 15 for molding the inner diameter surface of the green compact 1 ′ and the pair of upper punch 13 and lower punch 14 for molding the upper end surface and the lower end surface of the green compact 1 ′ are provided. Moves up and down relatively with respect to the die 12 and the core 15. In the molding die 11 of the present embodiment, the die 12, the core 15, and the upper punch 13 held by the elevating unit 30 constitute a movable side, and the lower punch 14 constitutes a stationary side. The die 12 is held by a first lifting table 17 that is driven up and down, and the core 15 is driven up and down together with the first lifting table 17 (die 12).

  As shown in FIG. 3, the powder filling unit 20 includes a casing 21, a partition member 22 that divides the internal space of the casing 21 into an inner housing portion 25 a and an outer housing portion 25 b, the partition member 22 as the casing 21, and further molding. A support mechanism that is removably supported with respect to the cavity 16 of the mold 11. The support mechanism mainly includes a support member 23 that supports an upper end portion of the partition member 22, and a support member 23 (and the partition member 22). ) Is supported by a pair of lifting cylinders 24, 24. Both the casing 21 and the partition member 22 are formed of a cylindrical body having an open lower end. The inner housing portion 25a and the outer housing portion 25b are loaded with the first powder M1 molded into the first compression molding layer 2 ′ and the second powder M2 molded into the second compression molding layer 3 ′, respectively. The The volume of the inner accommodating portion 25a is set to be larger than the volume of the inner diameter side region to be filled with the first powder M1 in the cavity 16, and the volume of the outer accommodating portion 25b is the second powder in the cavity 16. It is set larger than the volume of the outer diameter side region to be filled with M2.

  Here, the 1st powder M1 used by this embodiment corresponds to bearing layer 2, for example, contains copper powder of 10-30 mass%, and is a mixture of copper powder and iron powder which made most the remainder iron powder. Composed of powder. On the other hand, the second powder M2 is made of iron powder substantially corresponding to the base layer 3.

  In a state where the elevating cylinder 24 is in the extension limit shown in FIG. 3, the lower end of the casing 21 and the lower end of the partition member 22 are located on the same plane.

  The powder filling unit 20 having the above configuration includes a filling position where the first powder M1 loaded in the inner housing portion 25a and the second powder M2 loaded in the outer housing portion 25b can be simultaneously filled into the cavity 16. The cavities 16 are configured to move relative to each other between retreat positions spaced apart in the radial direction (the radial direction of the green compact 1 ′ to be molded). A powder supply pipe (not shown) is connected to each of the inner housing portion 25a and the outer housing portion 25b, and the powder filling unit 20 operates in one cycle (moves from the retracted position to the filling position and enters the cavity 16 in the first and second directions. After the powders M1 and M2 are filled and then moved from the filling position to the retracted position), a predetermined amount of the first powder M1 and the second powder are respectively added to the inner accommodation part 25a and the outer accommodation part 25b via the powder supply pipe. M2 is automatically supplied (supplemented).

  The elevating unit 30 includes a second elevating table 31 that holds the upper punch 13 so as to be elevable, and a pair of support columns 32 and 32 (for example, see FIG. 2 above) for guiding the second elevating table 31 up and down. A pressing force transmitting means 40 (see FIG. 6 and the like) for transmitting a downward pressing force applied from a press unit (not shown) to the upper punch 13, and a support table 34 disposed above the second lifting table 31. The second lift table 31 is supported by the support table 34 via a pair of lift cylinders (for example, air cylinders) 33 and 33. A press unit (not shown) included in the molding apparatus 10 is disposed on the upper side of the support table 34.

  As shown in FIGS. 6 and 8-10, the pressurizing force transmitting means 40 is mainly arranged coaxially with the upper punch 13 and is attached and fixed to the support table 34, and a pair of movable spacers. 42 and 42 and a pair of air cylinders 43 and 43 for moving the movable spacers 42 and 42 in the radial direction (horizontal direction) of the green compact 1 ′ to be molded. A guide member 44 that guides the forward and backward movement of the movable spacers 42 and 42 is provided on the upper surface.

  As shown in FIG. 7, the pair of support columns 32 are arranged symmetrically on one diagonal line that extends through the center of the second lifting table 31 (the axial center position of the pressure member 41) in plan view. In addition, the pair of lifting cylinders 33 are arranged symmetrically on other diagonal lines extending through the center of the second lifting table 31 in plan view.

  Each movable spacer 42 is a pressurizing position where pressure can be applied (transmitted) to the upper punch 13 for simultaneously compressing the powder M1, M2 filled in the cavity 16 with the lower punch 14 (FIG. 9). , 10) and a position where pressure is not applied to the upper punch 13 (see FIG. 6 and FIG. 8). More specifically, as the upper punch 13 (elevating unit 30) moves downward from the top dead center, the rod portion 43a of the air cylinder 43 extends, and the movable spacer 42 is in the above-described non-pressurizable position. To the pressure position (see FIGS. 6 and 8-10). On the contrary, as the upper punch 13 (elevating unit 30) moves upward from the bottom dead center, the rod portion 43a of the air cylinder 43 shortens, and the movable spacer 42 moves to the above-described pressurizing position. To the position where pressure cannot be applied.

  The molding apparatus 10 mainly has the above-described configuration, and the green compact 1 ′ is automatically molded by following the following procedure.

  First, as shown in FIG. 2, the die 12, the lower punch 14, and the upper end surface of the core 15 are positioned on the same plane (the cavity 16 is not formed in the molding die 11), and the retracted position is reached. The located powder filling unit 20 is moved to a filling position (position coaxial with the cavity 16) where the powder M1, M2 can be filled into the cavity 16 (see FIG. 3). At this time, the powder filling unit 20 including the casing 21 is moved while being pressed downward by a pressing mechanism (not shown), and the lower end of the casing 21 is placed on the upper end surface of the die 12 (first lifting table 17) at the filling position. Stops while being pressed. Further, at this time, the lifting unit 30 that holds the upper punch 13 so as to be movable up and down is not operated, for example, and is located substantially at the top dead center. Although detailed illustration is omitted, after the powder filling unit 20 moves to the filling position, the lifting cylinder 24 is shortened by a predetermined amount. Thereby, the partition member 22 is pressed downward, and the lower end of the partition member 22 is pressed against the upper end surface of the lower punch 14.

  As shown in FIG. 3, in the internal space of the powder filling unit 20 moved to the filling position, the first powder M1 and the second powder M2 are separated from each other in the radial direction of the green compact 1 ′ to be molded. It is loaded. That is, the first and second powders M1 and M2 are disposed outside the molding die 11 in which the cavity 16 is not formed in a state where the cavities 16 are separated from each other in the radial direction of the green compact 1 '. Note that at least one of the inner housing portion 25a and the outer housing portion 25b has a larger amount of raw material than the amount of the first and second powders M1, M2 to be filled in the inner diameter side region and the outer diameter side region of the cavity 16, respectively. The powder is loaded.

  Next, as shown in FIG. 4, the first elevating table 17 is moved up, and the die 12 and the core 15 are moved up relative to the lower punch 14. At the same time, the lifting cylinder 24 of the powder filling unit 20 is shortened to move only the casing 21 upward. That is, the die 12 and the core 15 are moved upward with respect to the lower punch 14 and the partition member 22. As a result, the cavity 16 is gradually formed in the molding die 11 with the lower end of the partition member 22 pressed against the upper end surface of the lower punch 14, and at the same time, the first powder M1 and the second powder M2 are molded. Filled into the inner diameter side region and the outer diameter side region of the cavity 16 in a state of being separated from each other in the radial direction of the power compact 1 ′.

  As described above, after arranging the powders M1 and M2 in the radial direction of the green compact 1 ′ to be molded outside the molding die 11 in which the cavity 16 is not formed, the mutual separation state If the movable side and the stationary side of the molding die 11 are moved relative to each other while maintaining the above, the formation of the cavity 16 and the simultaneous filling of the powders M1 and M2 into the cavity 16 can proceed simultaneously. The powder filling operation to 16 can be performed smoothly and efficiently.

  After the cavity 16 is filled with both powders M1 and M2 as described above, the lifting cylinder 24 of the powder filling unit 20 is extended to separate the partition member 22 from the cavity 16 (see FIG. 5). That is, the mutual separation state in the radial direction of the green compact 1 'to be molded of both powders M1, M2 is released. As a result, the first powder M1 and the second powder M2 come into contact with each other in the cavity 16. At this time, as described above, at least one of the inner housing portion 25a and the outer housing portion 25b of the powder filling unit 20 includes the first powder M1 to be filled in the inner diameter side region and the outer diameter side region of the cavity 16, respectively. A larger amount of powder than the amount of the second powder M2 is loaded (that is, the above-described release operation of the mutual separation state replenishes at least one kind of raw material powder among the plural kinds of raw material powders to be filled in the cavity 16. Therefore, the space formed by detaching the partition member 22 from the cavity 16 is filled with the powder loaded in one or both of the housing portions 25a and 25b. The As a result, the cavity 16 defined by the inner diameter surface of the die 11, the outer diameter surface of the core 15, and the upper end surface of the lower punch 14 is filled with the first powder M1 and the second powder M2. A green compact 1 'having a density can be formed. Then, as shown in FIG. 6, the powder filling unit 20 is moved from the filling position to the retracted position.

  Next, the elevating unit 30 (upper punch 13) is lowered, and the first and second powders M1 and M2 filled in the cavity 16 are compressed simultaneously between the upper punch 13 and the lower punch 14, and the first powder is compressed. A green compact 1 ′ composed of a first compression-molded layer 2 ′ formed by compression-molding M1 and a second compression-molded layer 3 ′ formed by compression-molding the second powder M2 is formed.

  Here, in the molding apparatus 10 of the present embodiment, the downward movement of the upper punch 13 (elevating unit 30), that is, the compression of the first and second powders M1, M2 filled in the cavity 16 is performed as follows. .

  First, when a pressing unit (not shown) is driven, the support table 34 starts to move downward (the support table 34 starts to be pressed downward), as shown in FIG. When the 33a extends, the second elevating table 31 moves down (rapidly) so that the upper end surfaces of the movable spacers 42 and 42 are located below the lower end surface of the pressing member 41. Next, as shown in FIG. 9, the rod portions 43a of the pair of air cylinders 43, 43 extend, and both movable spacers 42, 42 are disposed below the pressure member 41 (in the illustrated example, both movable The inner side surfaces of the spacers 42 and 42 abut each other at the axial center positions of the upper punch 13 and the pressure member 41). As a result, the movable spacers 42 and 42 apply (transmit) pressure to the upper punch 13 to compress the first and second powders M1 and M2 filled in the cavity 16 with the lower punch 14. It moves from the position where pressure is not applied to the position where pressure can be applied (transmitted). If the support table 34 is further pressed downward by the press unit while maintaining this state, the lower end surface of the pressurizing member 41 comes into contact with the upper end surfaces of the movable spacers 42 and 42 and the press unit 41 applies pressure. The pressure is transmitted to the upper punch 13 via the support table 34, the pressure member 41, the movable spacers 42 and 42, and the second lifting table 31. Accordingly, the first and second powders M1 and M2 are simultaneously compressed by the upper punch 13 and the lower punch 14, and the first compression molding layer 2 ′ and the second compression molding layer 3 ′ are laminated in the radial direction. A green compact 1 ′ is formed (see FIG. 10).

  Although illustration is omitted, after the green compact 1 ′ is formed, the die 12 (the first lifting table 17 is moved with respect to the lower punch 14 while the lifting unit 30 is moved up and down in a procedure reverse to the procedure described above. ) And the core 15 are moved downward, whereby the green compact 1 ′ is taken out from the cavity 16 of the molding die 11. When the elevating unit 30 (upper punch 13) moves to the top dead center, the molding 1 cycle operation of the green compact 1 'is completed. The green compact 1 ′ taken out from the cavity 16 is molded as the molding 1 cycle operation of the subsequent green compact 1 ′ starts and the powder filling unit 20 moves from the retracted position to the filling position. It is paid out of the device 1.

  The green compact 1 ′ obtained as described above becomes a sintered body by being heated and sintered under predetermined conditions in a sintering process (not shown). When the green compact 1 ′ is sintered, the first compression-molded layer 2 ′ is sintered together with the second compression-molded layer 3 ′ in contact with the second compression-molded layer 3 ′. When the body 1 ′ is sintered, a sintered body in which the bearing layer 2 and the base layer 3 are integrated can be obtained.

  The sintered body obtained in the sintering step is subjected to dimensional correction by sizing or the like as necessary, and the internal pores are impregnated with a lubricant such as lubricating oil in the oil impregnation step. Thereby, the sintered bearing 1 shown in FIG. 1 is completed.

  As described above, the compacting device 10 of the green compact 1 ′ according to the present invention is provided so as to be detachable from the cavity 16 of the molding die 11, and a plurality of kinds of raw materials are inserted into the cavity 16. A powder filling unit 20 including a partition member 22 that can fill the cavity 16 in a state where powders (first and second powders M1, M2) are separated from each other in the radial direction of the green compact 1 ′ is provided. .

  With the molding apparatus 10 having such a configuration, (1) the partition member 22 provided in the single powder filling unit 20 loaded with the first and second powders M1 and M2 is inserted into the cavity 16 (inside the cavity 16). In this state, both the powders M1 and M2 loaded in the powder filling unit 20 are filled in the cavity 16 at the same time, and then (2) the partition member 22 arranged in the cavity 16 is detached from the cavity 16. , The powder 16 can be filled into the cavity 16 in the state of being laminated in the radial direction of the green compact 1 ′ to be molded.

  In short, if the technical means according to the present invention is employed, when filling the cavity 16 with both powders M1, M2 laminated in the radial direction of the green compact 1 ′ to be molded, as in the prior art, Forming a plurality of shoeboxes (corresponding to the powder filling unit 20) stepwise to fill the cavities with raw powder step by step, or including a plurality of lower punches and partition members each moving up and down independently There is no need to use a mold and to operate a plurality of lower punches and partition members stepwise. Therefore, the time required from the start of the operation of the molding apparatus 10 to the completion of the powder filling into the cavity 16, and thus the molding 1 cycle time of the green compact 1 ′, can be greatly shortened, and the molding apparatus 10 is simplified as a whole. And can be made compact.

  Further, in the molding apparatus 10 according to the present invention, as the elevating unit 30 that holds the upper punch 13 so as to be movable up and down, the powders M1 and M2 filled in the cavity 16 between the upper punch 13 and the lower punch 14 are compressed. Using a movable spacer 42 that moves (transfers) between a pressurizing position that can apply (transmit) a pressurizing force to the upper punch 13 and a non-pressurizable position that does not apply the pressurizing force to the upper punch 13 The movable spacer 42 is moved from the non-pressurizable position to the pressure position as the upper punch 13 (second lifting table 31) is moved downward, and the pressure is increased as the upper punch 13 is moved upward. It was configured to move from the position to the position where pressurization is not possible.

  In this way, by selecting and using the movable spacer 42 having an appropriate vertical dimension, the upper punch 13 and the powder filling unit 20 are placed between the die 12 and the upper punch 13 during the execution of the powder filling process. While it is possible to ensure a vertical separation distance (large space) that does not interfere, the stroke amount in the vertical direction of the upper punch 13 that is required when performing the powder compression process can be reduced. Therefore, it is possible to avoid the press unit for pressurizing the upper punch 13 (elevating unit 30) downward, and hence the molding apparatus 10 from becoming unnecessarily large. More specifically, the green compact 1 ′ having a multilayer structure can be molded using an existing molding apparatus (for example, a molding apparatus for molding a green compact having a single layer structure).

  Further, since the movable spacer 42 is moved back and forth in the radial direction of the green compact 1 ′, the movable spacer 42 is moved between the pressurizing position and the non-pressurizable position. A simple structure such as an air cylinder 43 can be employed as a drive mechanism for moving the two positions between each other.

  Further, since the lifting unit 30 is further provided with a guide member 44 for guiding the mutual movement of the movable spacer 42 between the two positions, the movable spacer 42 can be accurately guided to the predetermined pressure position. . Therefore, the first and second powders M1, M2 filled in the cavity 16 can be appropriately compressed.

  From the above, according to the present invention, a multi-layered compact formed by laminating a plurality of compression-molded layers (in the above, first compression-molded layer 2 ′ and second compression-molded layer 3 ′) in the radial direction. The body 1 ′ can be molded efficiently and accurately.

  As mentioned above, although the shaping | molding apparatus 10 and the shaping | molding method of the compact 1 'which concern on embodiment of this invention were demonstrated, in the range which does not deviate from the summary of this invention, the shaping | molding apparatus 10 and a shaping | molding method are changed suitably. Can be applied.

  For example, in the molding apparatus 10 described above, the molding die 11 in which the die 12 and the core 15 constitute the movable side and the lower punch 14 constitutes the stationary side is used. On the contrary, the lower punch 14 Can form the movable side, and the molding die 11 in which the die 12 and the core 15 constitute the stationary side can be used.

  Although not shown, the movable spacer 42 is not divided in the radial direction of the green compact 1 ′ to be molded, and can be constituted by a single member.

  In the embodiment described above, the molding apparatus 10 (and the molding method) according to the present invention is employed when the green compact 1 ′ that becomes the hollow (cylindrical) sintered bearing 1 is molded. The molding apparatus 10 according to the present invention can be preferably used when molding a solid green compact. That is, when a solid green compact is molded, a molding die 11 from which the core 15 is omitted may be used. In this connection, the molding apparatus 10 according to the present invention can be preferably used when molding a green compact that becomes a sintered metal part (for example, a gear or a cam) other than a sintered bearing.

  In the embodiment described above, when the green compact 1 ′ having a two-layer structure in which the first compression molded layer 2 ′ and the second compression molded layer 3 ′ are laminated in the radial direction is formed. Although the invention is applied, the molding apparatus 10 according to the present invention can be preferably applied also when molding a green compact 1 ′ in which three or more compression molding layers are laminated in the radial direction. For example, when the green compact 1 ′ having a three-layer structure is molded, the powder filling unit 20 is provided so as to be detachable from the cavity 16 (and the casing 21). Having a partition member 22 that allows the cavity 16 to be filled in a state in which three kinds of raw material powders are separated from each other in the radial direction (in other words, the internal space of the casing 21 is divided into three spaces, In addition, a partition member 22 provided so as to be detachable from the cavity 16 and the casing 21 may be used.

  The technical means according to the present invention can perform the process of filling a plurality of types of raw material powders in a state where they are laminated in the radial direction of the green compact to be molded, only through a single process as described above. Therefore, if it is applied when molding a green compact 1 ′ having a multilayer structure of three or more layers, the green compact 1 ′ having a multilayer structure of three or more layers is greatly compared with the conventional method. And can be molded at low cost.

DESCRIPTION OF SYMBOLS 1 Sintered bearing 1 'Green compact 2 Bearing layer 2' 1st compression molding layer 3 Base layer 3 '2nd compression molding layer 10 Molding apparatus 11 Molding die 12 Die 13 Upper punch 14 Lower punch 15 Core 16 Cavity 20 Powder filling unit 22 Partition member 30 Lifting unit 40 Pressure transmission means 42 Movable spacer 43 Air cylinder 44 Guide member A Bearing surface B Mounting surface M1 First powder M2 Second powder

Claims (9)

A molding apparatus for molding a green compact formed by laminating a plurality of compression molding layers in the radial direction,
A cylindrical die that forms a cavity on the inner periphery, and a molding die having a pair of upper and lower punches that move up and down relative to the cavity;
A powder filling unit that fills the cavity with a plurality of types of raw material powders each molded into each compression molding layer,
The powder filling unit is provided so that it can be inserted into and removed from the cavity, and when inserted into the cavity, a partition member that can fill the cavity with a plurality of types of raw material powder separated from each other in the radial direction of the green compact. An apparatus for forming a green compact, comprising:   2. The green compact molding apparatus according to claim 1, wherein the molding die is disposed on the inner periphery of the die and has a core for molding the inner diameter surface of the green compact.   3. The green compact according to claim 1, wherein the powder filling unit moves between a filling position where a plurality of kinds of raw material powders can be filled in the cavity and a retreat position spaced radially from the cavity. Molding equipment. It further includes an elevating unit that holds the upper punch so that it can be raised and lowered,
The elevating unit includes a pressurizing position where a pressing force for compressing the raw material powder in the cavity can be applied to the upper punch and a non-pressurizing position where the pressing force is not applied to the upper punch. Having movable spacers that move between each other,
2. The movable spacer moves from the pressurization impossible position to the pressurization position as the upper punch moves downward, and moves from the pressurization position to the pressurization impossible position as the upper punch moves up. The green compact forming apparatus according to any one of?   5. The green compact molding apparatus according to claim 4, wherein the movable spacer moves between the pressurizing position and the non-pressurizable position by moving forward and backward in the radial direction of the green compact.   The green compact molding apparatus according to claim 4 or 5, wherein the elevating unit has a guide member that guides the mutual movement of the movable spacer between the pressurizing position and the non-pressurizable position. A method for molding a green compact formed by laminating a plurality of compression molding layers in the radial direction,
Each of the plurality of raw material powders molded into each compression molding layer is simultaneously filled into the cavity of the molding die in a state of being separated from each other in the radial direction of the green compact, and then the mutual separation state is released. Thereafter, a method of forming a green compact, wherein a plurality of types of raw material powders are simultaneously compressed.   After a plurality of kinds of raw material powders are separated from each other in the radial direction of the green compact on the outside of the molding die in which the cavity is not formed, the movable side of the molding die is kept stationary while maintaining the mutual separation state. 8. The green compact forming method according to claim 7, wherein the forming of the cavity and the filling of the plural kinds of raw material powders into the cavity proceed simultaneously by moving the side relative to each other.   The method for forming a green compact according to claim 7 or 8, wherein among the plural kinds of raw material powders, at least one kind of raw material powder is replenished in the cavity, and the mutual separation state is released.

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