JP4571791B2 - Powder molded body manufacturing method and sintered part - Google Patents

Description

  The present invention relates to a method for producing a powder molded body, and more particularly to a method for producing a powder molded body formed by a compression molding process with an uncompressed layer and a high-strength sintered part using the powder molded body.

  Powder is filled into a cavity defined by a die for forming the outer peripheral surface of the powder molded body, an upper punch for forming the upper end surface, and a lower punch for forming the lower end surface, and the upper and lower punches are stroked using a press. A molded body having a predetermined compression density is manufactured, and the molded body is sintered to produce parts and tools. Japanese Patent Application Laid-Open No. 2001-089802 describes a method of forming a shaft hole in a powder molded body obtained by compression-molding material powder filled in a cavity with an upper and lower punch. With reference to FIGS. 8A and 8B, the operation of the punching pin will be described. In FIG. 8 (a), a punching pin 15 is disposed on the side surface of the die 5, and the punching pin 15 is filled by making the punching pin axis line coincide with the neutral line generated in the compression direction of the filling powder layer 3 between the upper and lower punches. Insert into powder layer 3. Reference numeral 16 denotes a through hole through which the punching pin 15 is inserted. FIG. 8B shows a state after the shaft hole is formed by the punching pin 15. The powder 17 punched out from the filled powder layer 3 is discharged from a discharge port provided in the die 5 through a through hole 16. After that, with the punching pin inserted, the lowering stroke amount of the upper punch 9 from the upper end surface and the stroke amount of the lower punch 7 from the lower end surface are set to be the same, and the filled powder is compressed by the upper and lower punches. To form a molded body. A powder molded body having a shaft hole is manufactured by pulling a punching pin from the molded body.

  In the above method, there is an uncompressed product called a punching pin in the powder layer compressed in the compression step. When the powder is uniformly filled and compression-molded without taking such conditions into consideration, referring to FIG. 1 (a), the part a which is compressed by the punching pin and the upper and lower punches during compression and the part b which is not affected by the punching pin And the compression ratio differs, so that not only the density of the portion b does not increase, but also a good molded article cannot be obtained.

  For example, in Japanese Patent Laid-Open No. 6-198497, there is a molding method for obtaining a molded body having a stepped lower end portion by compressing powder filled in a die using a concentrically fitted lower punch, and filling the inside of the die. It is disclosed. In this case, the relative moving speed of the upper punch and the lower punch with respect to the die is controlled by setting the same speed ratio as the ratio of the compression amount of each step of the molded product. When compression molding such multi-stage powder compacts, changing the compression ratio of each step part means that during the compression molding, the powder moves from a step part with a high compression density to a lower part part and a good compact is obtained. I can't. Similar movement of the powder occurs when there is an uncompressed layer, such as a punched pin, inside the packed powder layer to be compressed.

  Such a phenomenon is influenced by the volume of the non-compressed layer and the amount of powder to be filled. For example, when a processing tool or the like is manufactured by sintering, a shaft hole is formed in the powder compact, and the compression density may be increased to about 2.5 to improve the strength after sintering. Further, depending on the parts to be manufactured, compression molding may be performed with the compression ratio set to 3. In such a case, the above-mentioned inconvenience becomes more noticeable because the powder filling amount increases. Therefore, it is necessary to fill a powder that matches the shape of the non-compressed layer such as a punching pin when filling the powder so that the packed layer related to the non-compressed layer and the other packed layer have a constant compression ratio. .

A powder molded body 1 shown in FIG. 1 (a) has a shaft hole 2 formed by the punching pin disclosed in the above prior art, and fits the outer shape of the punching pin inside the die as shown in FIG. The powder filled in is compression molded with an upper and lower punch at a compression ratio of 3. In FIG. 2, 2 indicates the position where the shaft hole is formed, and the amount of powder calculated from the volume and compressibility of the powder compact 1 is the uniform powder filling layer 3 (hereinafter referred to as the filling powder layer) and the filling. The filling layer 4 is distributed and filled in the filling layer 4 formed above and below the powder layer 3, and the filling layer 4 is distributed above and below the filling powder layer 3 in consideration of the shape of the punching pin (hereinafter referred to as supplementary powder layer). It is. Since the obtained powder compact 1 has a high compression ratio of 3, the compressive density difference between the upper and lower layers close to the punch and the neutral zone b part or the compressive density difference between the part a and the other part becomes large. When 1 was sintered, for example, deformation as shown in FIG. 1B occurred. Furthermore, as shown in FIG. 2, filling the powder so as to conform to the shape of the non-compressed layer such as a punching pin, the shape of the end surface of the powder molded product regulated by the upper and lower punches and the shape of the upper and lower end surfaces of the non-compressed layer If they do not match, it is difficult.
JP 2001-089802 A JP-A-6-198497

  The present invention provides a powder molding method comprising a powder filling method and a compression method suitable for compression molding a packed powder layer having an uncompressed layer, and further uses a powder molded body by such a manufacturing method. An object is to provide a high strength sintered part.

In order to solve the above problems, the present invention is a molding comprising a die that forms the outer peripheral surface of a molded body, upper and lower molding punches that move relatively inside the die, and a control means that controls the amount of movement of the punch. In a manufacturing method for manufacturing a powder compact by compressing a packed powder layer including an uncompressed layer by an apparatus, upper and lower powder replenishing punches that can be driven independently of the molding punch are projected onto the uncompressed layer. A powder amount calculated from the volume of the powder molded body excluding the volume of the non-compressed layer and the compression ratio is formed between the upper and lower molding punches. And the step of allocating the filling powder layer and the replenishing powder layer formed so as to be compressible by the powder replenishing punch above and below the filling powder layer, and the molding punch and the powder replenishing punch are simultaneously compression-molded. Control movement to complete Lower by, have a compression step of compression molding while replenishing the powder replenishing powder layer packed powder layer, the allocation process, which is located below the die and punch and the lower forming punch for the lower molding Filling process for filling powder into the space formed by the powder replenishing punch, and lowering the upper forming punch down to the upper surface of the filling powder and maintaining the space between the upper and lower forming punches And a transfer step for forming a filling powder layer and a lower replenishment powder layer between upper and lower molding punches, and a space formed above the filling powder layer by the transfer step, As the space where the powder replenishing punch is arranged, the upper replenishing powder layer is formed by penetrating the upper forming punch vertically and filling the column-shaped through holes provided in the upper refining punch with powder. From filling process to Characterized in that that.

According to this configuration, the amount of powder calculated from the volume of the powder molded body excluding the volume of the non-compressed layer and the compression ratio in the distribution step is set to the filled powder layer between the upper and lower molding punches, and the filled powder layer. The replenishment powder layer formed so as to be compressible by the powder replenishing punch is distributed above and below the powder, and the powder of the replenishing powder layer is compressed by the powder replenishing punch and replenished to the filling powder layer, and compression molding is performed. As a result, the influence of the non-compressed layer in the compression process can be avoided, and a powder compact having a predetermined compression ratio can be obtained. There is no deformation.

Furthermore, in the present invention, a punching pin device for forming a shaft hole in the powder molded body on the side surface of the die is provided, and after the distribution step , the punching pin is inserted into the filling powder layer, and the punching pin is inserted. In the compression step, a powder replenishing punch is provided outside the projected region of the punching pin, and provided with powder replenishing punches arranged apart from the inner surface of the die, respectively, and excluding the volume of the uncompressed layer The amount of powder calculated from the volume and the compression ratio is calculated by calculating the volume of the non-compressed layer as the volume of the punching pin, allocating at least the calculated powder amount to the filled powder layer and the supplementary powder layer, The punching pin is pulled out after completion of the process.

  According to this configuration, a compacted powder compact with a shaft hole as designed can be easily manufactured using a conventional multi-stage press, and by sintering the powder compact manufactured by such a manufacturing method, A machining tool having a shaft hole for supporting and having high strength can be manufactured at low cost.

  Furthermore, according to the present invention, the amount of powder distributed to the replenishment powder layer is multiplied by (compression ratio-1) of the calculated amount of powder in the horizontal projection region of the non-compressed layer during non-compression. The amount of the powder is calculated as follows. According to such a configuration, since the amount of powder in the appropriate replenishment powder layer can be calculated at the time of designing the powder compact, the arrangement of the replenishment powder layer can be easily set, the design of the punch, and the position of the powder replenishment punch in the filling process Control becomes easy.

Further, the present invention provides a non-molding apparatus comprising: a die that forms an outer peripheral surface of a molded body; upper and lower molding punches that move relatively inside the die; and a control unit that controls the amount of movement of the punch. In a manufacturing method for manufacturing a powder compact by compressing a packed powder layer including a compression layer, upper and lower powder replenishing punches that can be driven independently of the molding punch are disposed outside the projection region of the non-compressed layer. Filled powder layer formed adjacent to the molding punch at a position and formed between the upper and lower molding punches by a powder amount calculated from the volume and compression rate of the powder compact excluding the volume of the non-compressed layer And a distribution step of distributing the powder powder replenishment layer above and below the filling powder layer so as to be compressible by the powder replenishment punch, and the molding punch and the powder replenishment punch are simultaneously completed. By controlling the amount of movement The powder replenishing powder layer and a compression step of compression molding while replenishing the filling powder layer, wherein the compression step, the total amount of movement in the up and down the forming punch and vertical powder replenishing punches, each of the compression stroke A pre-compression step of pre-compressing the filling powder layer and the replenishment powder layer by moving the movement amount corresponding to a certain ratio of the upper and lower powder replenishment with the upper and lower molding punches fixed after the pre-compression step A powder replenishing step in which a predetermined amount of the punch is moved to replenish the powder from the replenished powder layer to the pre-compressed filled powder layer, and the upper and lower molding punches and the upper and lower powder replenishing punches are driven to form a powder compact having a predetermined shape And a final compression step.

According to such a configuration, since most of the powder of the replenishing powder layer can be replenished at a time when the powder density of the filling powder layer is suitable for replenishment, the deviation of the compressed density of the powder molded body layer can be reduced, The movement of the powder after the powder density is increased is avoided, and the quality of the powder compact is maintained .
The molding punch structure of the present invention includes a die that forms the outer peripheral surface of the molded body, upper and lower molding punches that move relatively inside the die, and a control unit that controls the amount of movement of the punch. In a manufacturing method for manufacturing a powder molded body by compressing a filling powder layer including an uncompressed layer by a molding device,
Upper and lower powder replenishment punches that can be driven independently of the molding punches are provided adjacent to the molding punches at positions outside the projection area of the uncompressed layer,
The amount of powder calculated from the volume of the powder compact excluding the volume of the uncompressed layer and the compression ratio is used to replenish the powder above and below the filled powder layer. A distribution step of allocating to a replenishing powder layer formed compressible with a punch;
A powder forming process comprising: a compression step of compressing and forming the powder of the replenishing powder layer while replenishing the powder of the replenishing powder layer by controlling the amount of movement of the forming punch and the powder replenishing punch so as to complete the compression molding simultaneously. A punch structure for molding used in a manufacturing method of a body,
In any one of the upper and lower molding punches, at least one column-shaped through hole penetrating vertically from the molding surface of the molding punch is provided, and the molding punch is independent of the molding punch. A moving powder replenishing punch is provided.
In addition, the sintered part of the present invention is manufactured by sintering the powder molded body manufactured by the above-described method for manufacturing a powder molded body of the present invention.

  A method for producing a powder molded body according to the present invention will be described below with reference to the drawings. FIG. 1A is a view showing a powder molded body having a shaft hole, and FIG. 1B is a view showing a state after the powder molded body of FIG. 1A is sintered. FIG. 2 is a view showing a powder filling state before compression molding of the powder compact shown in FIG. FIGS. 3A, 3B, 3C and 3D are cross-sectional views for explaining a filling powder distribution step in the method for producing a powder molded body according to the present invention. 4 (a), 4 (b), 4 (c) and 4 (d) are schematic views for explaining a powder compression step in the method for producing a powder molded body according to the present invention. 5A and 5B are a plan view and a side view showing a tool according to an embodiment obtained by sintering a powder compact according to the present invention. 6 and 7 are explanatory diagrams for explaining the amount of supplement powder. 8A and 8B are schematic views showing the operation of the punching pin.

  In the present embodiment, a method for manufacturing a simple rectangular parallelepiped powder compact having a shaft hole 2 in the neutral zone shown in FIG. An NC controlled multi-stage press (not shown) was used as a manufacturing apparatus, and tungsten carbide WC powder mixed with a binder was used as the powder. A punching pin device (not shown) for forming the shaft hole 2 in the filling powder layer 3 is provided on the side surface of the die 5 having a rectangular cross section shown in FIG. 3B in a direction perpendicular to the paper surface of FIG. It is arranged. The lower punch attached to the lower ram of the multistage press is attached to 7a, 7b, 7c and another lower ram, and is divided into punches 8a, 8b located outside the projection area of the shaft hole 2. Correspondingly, the upper punch attached to the upper ram of the multi-stage press is also divided into 9a, 9b, 9c and 10a, 10b attached to another upper ram.

  As will be described later, in the present embodiment, the lower punches 7a, 7b, 7c and the upper punches 9a, 9b, 9c each constitute a molding punch that compresses and forms a powder, and the lower punch 8a, 8b and the upper punches 10a and 10b constitute a powder replenishing punch that operates integrally to replenish powder. The operation and the amount of movement of each of the upper and lower punches are controlled by setting in advance in a storage device that constitutes the NC control device of the multistage press.

  In the powder filling process, the lower forming punches 7a, 7b, 7c and the lower replenishing punches 8a, 8b are moved based on a command from the NC controller, and the distance from the upper end surface of the die 5 is shown in FIG. Fixed in the position shown. The WC powder was filled up to the upper end surface in the die 5 by a known powder filling device. The amount of filled powder is calculated from the amount of powder constituting the powder compact 1 after molding, that is, the actual volume of the powder compact 1 obtained by subtracting the volume corresponding to the shaft hole 2 (volume of the punching pin) and the compression ratio. The amount of powder punched by the pin was added.

  After the powder filling is completed, the upper forming punches 9a, 9b, 9c and the upper powder replenishing punches 10a, 10b are moved downward to the upper end position of the die 5 in contact with the top surface of the filled WC powder, and subsequently transferred. Move on to the process. In the transferring step, the upper forming punches 9a, 9b, 9c and the lower forming punches 7a, 7b, 7c are transferred downward by an amount corresponding to 4b in the figure while maintaining the interval shown in FIG. ). In the transfer process of the present embodiment, it is necessary to align the axis of the shaft hole formed in the molded body with the position corresponding to the axis of the punching pin installed in the die, and if necessary, the upper powder replenishing punch 10a. 10b and the lower powder replenishing punches 8a and 8b are moved by the same amount relative to the die to adjust the position of the shaft hole 2 to coincide with the axis of the punch pin. went.

  In FIG.3 (b), 4a, 4a formed after the said transfer process is a lower supplementary powder layer, and 4b, 4b is an upper supplementary powder layer. In the present embodiment, the total powder amount of the replenishment powder layers of the replenishment powder layers 4a and 4b is an amount corresponding to the amount of powder affected by the non-compression layer (punching pin) in the compression step. As a replenishment powder layer divided into four above and below the filling powder layer 3, outside the projected region of the punching pin indicated by a broken line in FIG. 2, left and right and at a position spaced from the inner surface of the die 5. Allocated. The amount of replenishment powder affected by the non-compressed layer will be described later. In the present embodiment, a punching pin having the same diameter as the shaft hole 2 is inserted into the filling powder layer 3 after the transfer step, and the subsequent compression process is performed with the punching pin inserted into the filling powder layer 3. It was.

  Next, the amount of powder constituting the replenishing powder layer will be described. FIG. 6 shows a cross section in the compression direction of the powder compact 1 in which the shaft hole 2 is uneven. In this cross section, the horizontal plane P1 perpendicular to the compression direction passing through the vicinity of the upper end of the shaft hole 2, that is, the vicinity of the upper end of the non-compression layer, and the compression direction passing through the vicinity of the lower end of the shaft hole 2, that is, the lower end of the non-compression layer. When divided into the upper layer W1, the intermediate layer W2, and the lower layer W2 by the horizontal plane P2, the upper layer W1 and the lower layer W3 are not affected by the non-compressed layer.

  As is apparent from the figure, the powder corresponding to the intermediate layer W2 is affected by the non-compressed layer 2 during compression. FIG. 7 is a diagram schematically showing the powder filling state, and the reference numerals are the same as those shown in FIG. FIG. 7A shows the powder filling state when the compression ratio is 3, divided into unit powder amounts. 3 is a filling powder layer, and 4 (a) and 4 (b) are supplementary powder layers. Since the amount of the replenished powder layer is equivalent to a compression rate of 1 and the amount of powder is not related to the lateral movement during compression, the intermediate layer W2 affected by the uncompressed layer after molding shown in FIG. Is the amount of powder obtained by subtracting the amount corresponding to compression rate 1 from the amount of powder obtained by multiplying the compression rate by 3, that is, twice the amount of powder in the horizontal projection region of the uncompressed layer when not compressed. FIG. 7B shows a case where the compression ratio is 2, and the amount of powder in the supplementary powder layers 4 (a) and 4 (b) is influenced by the uncompressed layer after molding shown in FIG. 7 (c). The amount corresponding to W2, that is, the amount of powder obtained by multiplying the amount of powder in the horizontal projection region of the uncompressed layer at the time of non-compression by the compression rate 2, and subtracting the amount of powder corresponding to the compression rate 1. From the above results, the amount of powder affected by the non-compressed layer is expressed by a general formula, and the amount of powder in the horizontal region of the non-compressed layer in the packed state × (compression ratio-1) is obtained. Amount.

  When the cross-sectional shape of the non-compressed layer approximates a square, the powder amount of the replenishment powder layer is calculated by the above formula. However, in the case of an uncompressed layer having a convex part at the top or bottom, it always passes through the top of the convex part. It is not necessary to limit the layer affected by the non-compressed layer by the horizontal plane, and the substantial volume of the non-compressed layer that affects the powder movement at the time of compression may be roughly calculated. Further, depending on the shape of the non-compressed layer, an appropriate amount of powder in the supplemental powder layer may be obtained by experiment.

  FIGS. 3C and 3D are diagrams showing another embodiment for forming a filling powder layer and a supplementary powder layer. In FIG. 3C, the positions of the lower molding punches 7a, 7b and 7c and the lower powder replenishing punches 8a and 8b from the upper end surface of the die 5 are indicated by the filling powder layer 3 and the lower replenishing powder layer 4a. The powder is filled while being held at the position to be formed. The distance between the upper surfaces of the lower molding punches 7a, 7b and 7c and the upper surfaces of the lower powder replenishing punches 8a and 8b is set based on the powder amount calculated by the above-described replenishing powder amount calculation method. Next, the upper molding punches 9a, 9b, 9c are moved downward until they contact the upper end surface of the filling powder layer 3, and the upper molding punches 9a, 9b, 9c and the lower molding punch are maintained while maintaining the distance between the upper and lower molding punches. 7a, 7b, 7c and lower powder replenishing punches 8a, 8b are both moved downward by an amount corresponding to the height of 4a set based on the replenishing powder amount, as shown in FIG. 3 (d). The upper replenishing powder layer spaces 10′a and 10′b are formed in the upper portion. The heights of the spaces 10'a and 10'b are equal to the height of 4a set based on the amount of the replenishing powder. Next, after filling the spaces 10′a and 10′b with the powder to form the replenishing powder layer 4b, the upper powder replenishing punches 10a and 10b are moved down to the upper surface of the replenishing powder layer 4b to complete the filling. To do. That is, it is the same as the state shown in FIG. In this state, the whole is transferred so that the punching pin matches the position indicated by the broken line 2.

  Next, the compression process will be described with reference to FIGS. 4 (a), (b), (c), and (d). In FIG. 4, all punches and dies are omitted for simplicity. In the compression process, preliminary compression was performed as the first step. In FIG. 4 (a), the upper molding punches 9a, 9b, 9c and the lower molding punches 7a, 7b, 7c are filled with a movement amount corresponding to 20% of the total movement amount from the start of compression to the end of compression molding. At the same time, the upper powder replenishing punches 10a and 10b and the lower powder replenishing punches 8a and 8b compress the layer 3 with a movement amount corresponding to 20% of the total movement amount from the start of compression to the end of compression molding. The pre-compression was carried out to the state shown in FIG.

  Subsequently, powder replenishment was performed as a second step. In FIG. 4B, while the upper molding punches 9a, 9b, 9c and the lower molding punches 7a, 7b, 7c are stopped, the upper powder replenishing punches 10a, 10b and the lower powder replenishing punches 8a, 8b The replenishment powder layers 4a and 4b are compressed with a movement amount of about 60% of the total movement amount until the end of compression molding, and the powder is replenished to the filling powder layer 3 to obtain the state shown in FIG. The third step is a final compression step, and the upper molding punches 9a, 9b, 9c and the lower molding punch 7a from the state shown in FIG. 4 (c) to the powder compact 11 shown in FIG. 4 (d). 7b and 7c are moved so that the packed powder layer 3 is compressed by a moving amount of 80% of the total moving amount until the end of compression molding, and at the same time, the upper powder replenishing punches 10a and 10b and the lower powder replenishing punches 8a and 8b are moved. Were moved so as to compress the replenishing powder layers 4a and 4b with a movement amount of approximately 20% of the total movement amount until the end of compression molding.

  After completion of the compression molding, the punching pin is pulled out from the powder molded body, and the lower molding punches 7a, 7b, 7c and the lower powder replenishing punches 8a, 8b are raised to the upper end of the die 5 or the die 5 is moved downward. Thus, the powder compact 11 is taken out from the die and conveyed to the sintering process. As can be understood from the above description, the upper punch and the lower punch may be configured by a forming punch and a filling punch that can be driven independently of the forming punch. In addition, when the forming punch is divided into a plurality of parts and a multi-stage powder compact is formed, the manufacturing method of the present invention in which a powder replenishment layer is formed and compression molding is performed while replenishing powder can be applied. In the case of a powder compact with a simple shape as in this embodiment, it is not necessary to use an NC-controlled multi-stage press, and a powder replenishing punch that can be driven independently is inserted into the upper and lower molding punches. It is also possible to implement the present invention by controlling the punch speed by hydraulic control or the like and by controlling the amount of punch movement by a limit switch or the like. The movement amount of the upper and lower punches in the above embodiment is a relative movement amount with respect to the die, and may be a die fixing method or a withdrawal method.

  In the above embodiment, the punching pin has been described as the non-compressed layer of the filled powder layer. However, when forming a powder molded body on the outer periphery of a solid part or using a core for forming a hollow powder molded body The manufacturing method of the present invention can also be applied to cases. In such a case, the amount of powder to be filled can be calculated from the volume obtained by subtracting the volume of the non-compressed layer from the total volume of the powder compact and the compression ratio, and the amount of powder in the supplementary powder layer is the uncompressed layer at the time of non-compression. The amount of powder in a layer horizontal to the compression direction in which there is, that is, the amount of powder in the horizontal projection region of the non-compressed layer at the time of non-compression is calculated by the equation: The position where the replenishment powder layer is formed can be set in one or a plurality of positions outside the projection area of the non-compressed layer and at a position where uniform replenishment is possible according to the shape of the powder molded product. Furthermore, it is desirable that the replenishment powder layer is set apart from the inner surface of the die.

  5 (a) and 5 (b) are diagrams showing a cutting tool 13 having a high compression density and a high strength having a shaft hole 12 obtained by sintering a powder compact formed by the manufacturing method according to the present invention. Thus, it is shown that a powder compact having a complicated shape can be produced by selecting the shape of the upper and lower punches and performing the same process as the above method.

  According to the manufacturing method of compressing a packed powder layer including an uncompressed layer according to the present invention to form a powder molded body, the upper and lower molding punches and the upper and lower powder replenishing punches that can be driven independently of each other The amount of powder calculated from the volume of the powder compact excluding the volume of the non-compressed layer and the compression ratio is filled between the upper and lower molding punches, and the powder is replenished above and below the filled powder layer. When the density of the powder to be compressed is not so high, compression molding is performed while replenishing the powder to the filling powder layer. As a result, even if the powder filling amount is increased to increase the compression density, the influence of the non-compressed layer can be avoided, and a powder compact having a predetermined compression ratio can be obtained, and the molded powder compact can be obtained. There is little deviation in density in the inner layer of the steel, and it is not deformed by sintering.

  The timing of powder replenishment from the replenishing powder layer by the movement of the powder replenishing punch can be set in relation to the density of the powder in the filling powder layer by the forming punch. Even if the replenishment powder amount is completely replenished while the powder density is very low, there is no replenishment effect, and when the powder density is increased to some extent, the same effect as the above-mentioned defect of the compact due to the movement of the powder is brought about. The powder replenishment after the pre-compression process in which the movement of the molding punch is stopped and the powder replenishment punch is moved also needs to be experimentally determined for the pre-compression amount and the replenishment powder amount to be performed at that time. In the case of a powder compact, that is, in the case of a part or tool that is normally manufactured by sintering, and when the compression ratio is 2.5 to 3, it is desirable to replenish the powder when the pre-compression amount is around 20%. .

It is a figure which shows the state after sintering and the powder molded object which has a shaft hole. It is a figure which shows the filling state of the powder before the compression molding of the powder compact shown in FIG. It is sectional drawing for demonstrating the filling process and the transfer process which distribute the filling powder in the manufacturing method of the powder compact | molding | casting by this invention. It is the schematic for demonstrating the compression process of the powder in the manufacturing method of the powder compact | molding | casting by this invention. It is the top view and side view which show the tool of one Embodiment obtained by sintering the powder compact | molding | casting by this invention. It is sectional drawing of the powder compact | molding | casting by this invention for demonstrating the amount of replenishment powder. It is a schematic diagram which shows the powder filling state for demonstrating the amount of replenishment powder. It is the schematic which shows the action | operation of a punch pin.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Powder compact, 2 axial hole, 3 filling powder layer, 4 supplementary powder layer, 5 die | dye, 7 lower molding punch, 8 lower powder supplementing punch, 9 upper molding punch, 10 upper powder supplementing punch, 15 punching Pin

Claims (6)

Filled powder containing an uncompressed layer by a molding apparatus comprising a die that forms the outer peripheral surface of the molded body, upper and lower molding punches that move relatively inside the die, and a control means that controls the amount of movement of the punch. In the production method for producing a powder compact by compressing the layer,
Upper and lower powder replenishment punches that can be driven independently of the molding punches are provided adjacent to the molding punches at positions outside the projection area of the uncompressed layer,
The amount of powder calculated from the volume of the powder compact excluding the volume of the uncompressed layer and the compression ratio is used to replenish the powder above and below the filled powder layer. A distribution step of allocating to a replenishing powder layer formed compressible with a punch;
By controlling the amount of movement to complete the simultaneous compression molding and the molding punch and the powder replenishing punch, it has a compression step of compression molding while replenishing the powder replenishing powder layer packed powder layer,
The distribution step is a filling step of filling a powder in a space formed by the die, a lower molding punch, and a lower powder replenishment punch positioned below the lower molding punch;
The upper molding punch is moved down to the upper surface of the filling powder, and the upper and lower molding punches are moved downward together with the lower powder replenishing punch while maintaining the interval, so that the filling powder layer between the upper and lower molding punches and the lower replenishment are supplied. A transfer step of forming a powder layer;
A space formed on the upper side of the packed powder layer by the transfer step, and provided in the upper molding punch through the upper molding punch vertically as a space in which the upper powder replenishing punch is disposed. And a filling step of filling the columnar through-holes with powder to form an upper replenishing powder layer . A punching pin device for forming a shaft hole in the powder molded body on the side surface of the die,
In the one in which the punching pin is inserted into the filling powder layer after the distribution step is completed , and the compression step is performed in a state where the punching pin is inserted,
Provided above and below the punching pin projection area is a powder replenishment punch arranged at a distance from the inner surface of the die, respectively,
The amount of powder calculated from the volume of the powder compact excluding the volume of the non-compressed layer and the compression ratio is calculated by calculating the volume of the non-compressed layer as the volume of the punch pin, and at least the calculated powder amount Distributing to the replenishment powder layer,
2. The method for producing a powder compact according to claim 1, wherein the punching pin is pulled out after completion of the compression step. The amount of powder distributed to the replenishment powder layer is the amount of powder calculated by multiplying the amount of powder in the horizontal projection region of the non-compressed layer at the time of non-compression among the calculated powder amounts (compression ratio-1). The method for producing a powder molded body according to claim 1, wherein the powder molded body is provided . Filled powder containing an uncompressed layer by a molding apparatus comprising a die that forms the outer peripheral surface of the molded body, upper and lower molding punches that move relatively inside the die, and a control means that controls the amount of movement of the punch. In the production method for producing a powder compact by compressing the layer,
Upper and lower powder replenishment punches that can be driven independently of the molding punches are provided adjacent to the molding punches at positions outside the projection area of the uncompressed layer,
The amount of powder calculated from the volume of the powder compact excluding the volume of the uncompressed layer and the compression ratio is used to replenish the powder above and below the filled powder layer. A distribution step of allocating to a replenishing powder layer formed compressible with a punch;
By controlling the amount of movement to complete the simultaneous compression molding and the molding punch and the powder replenishing punch, it has a compression step of compression molding while replenishing the powder replenishing powder layer packed powder layer,
In the compression step, the filling powder layer and the supplementary powder layer are moved by moving the upper and lower molding punch and the upper and lower powder replenishment punch by a movement amount corresponding to a fixed ratio of the total movement amount in each compression step. A pre-compression process for pre-compression,
A powder replenishing step of replenishing the pre-compressed filled powder layer from the replenished powder layer by moving the upper and lower powder replenishing punch by a predetermined amount with the upper and lower molding punches fixed after the pre-compressing step;
A method for producing a powder molded body comprising: a final compression step of driving the upper and lower molding punch and the upper and lower powder replenishing punch to obtain a powder molded body of a predetermined shape . Filled powder containing an uncompressed layer by a molding apparatus comprising a die that forms the outer peripheral surface of the molded body, upper and lower molding punches that move relatively inside the die, and a control means that controls the amount of movement of the punch. In the production method for producing a powder compact by compressing the layer,
Upper and lower powder replenishment punches that can be driven independently of the molding punches are provided adjacent to the molding punches at positions outside the projection area of the uncompressed layer,
The amount of powder calculated from the volume of the powder compact excluding the volume of the uncompressed layer and the compression ratio is used to replenish the powder above and below the filled powder layer. A distribution step of allocating to a replenishing powder layer formed compressible with a punch;
A powder forming process comprising: a compression step of compressing and forming the powder of the replenishing powder layer while replenishing the powder of the replenishing powder layer by controlling the amount of movement of the forming punch and the powder replenishing punch so as to complete the compression molding simultaneously. A punch structure for molding used in a manufacturing method of a body,
In one molding punch before Symbol vertical molding punches, provided with at least one columnar through hole penetrating from the molding surface of the molding punch up and down, independently of the molding punch into the vent hole A punch structure for molding, comprising a powder replenishing punch that moves to the surface . A sintered part produced by sintering a powder compact produced by the production method according to any one of claims 1 to 4 .

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