JP7526684B2 - Molding method, powder filling device, and molding device - Google Patents

Description

The present invention relates to a molding method for molding a molding powder inside a cavity, and further to a powder filling device for filling a cavity with molding powder and a molding device to which the powder filling device is applied.

There is a known technology for obtaining a green body by filling the mold cavity of a molding device with molding powder and pressing it into a desired shape. For example, Patent Document 1 describes a technology in which a cavity is formed by inserting a lower punch into the die (mortar-shaped) of a mold, and the inside of this cavity is filled with molding powder from a powder filling device (filling process), while the upper punch is lowered to perform pressure molding (pressurizing process).

In the filling process, the powder filling device moves over the top surface of the die at the cavity position, so that the surface of the molding powder filled in the cavity is leveled by what is called leveling. In the invention described in Patent Document 1, in this state, a process (underfill process) is performed to raise the die relative to the lower punch, so that the top surface of the molding powder filled in the cavity is positioned lower than the top surface part of the die that defines the cavity opening, making it possible to prevent the molding powder from scattering outside the cavity.

In the invention described in Patent Document 1, a molding cycle that combines the above-mentioned filling process, underfill process, and pressurizing process is performed multiple times. In recent years, as molding tact times have increased, it has become necessary to perform the above-mentioned molding cycle at high speed. Even if an underfill process is performed, it is difficult to avoid the problem of the molding powder filled in the cavity scattering outside the cavity.

JP 2009-235452 A

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide a molding method, a powder filling device, and a molding device that can prevent the scattering of molding powder.

In order to achieve the above object, the molding method according to the present invention comprises the steps of:
A molding method for molding a molding powder inside a cavity formed by inserting a lower punch into a die, comprising the steps of:
filling the cavity with molding powder;
a step of closing an opening of the cavity filled with molding powder;
and a step of raising the die relative to the lower punch while the opening of the cavity is closed.

In the molding method according to the present invention, a step of closing the opening of the cavity filled with molding powder (closing step) is performed prior to the step of raising the die relative to the lower punch (underfilling step), and the underfilling step is performed with the cavity opening closed. Therefore, when the underfilling step is performed, the inside of the cavity is sealed, and even if the molding cycle is performed at high speed, the molding powder filled in the cavity can be effectively prevented from scattering outside the cavity. In addition, after the underfilling step is completed, the upper surface of the molding powder filled in the cavity is positioned lower than the upper surface portion of the die that defines the cavity opening, and the molding powder can be prevented from scattering outside the cavity.

In addition, by preventing the molding powder from scattering, it is possible to keep the amount of molding powder filled into the cavity constant and to fill the cavity uniformly with the molding powder. Therefore, even for small molded bodies, it is possible to prevent variations in the molding dimensions of the molded body, make the density of the molded body uniform, and prevent cracks and chips from occurring in the molded body.

In addition, molding equipment may be equipped with sliding parts for raising and lowering the die during the underfill process, etc., and by preventing the molding powder from scattering, it is possible to prevent problems such as molding powder getting into the sliding parts and causing abnormal wear.

In addition, by preventing the molding powder from scattering, it is possible to increase the ratio of the net molding powder (powder yield) that is actually used to mold the molded body within the cavity out of the molding powder filled in the cavity.

Preferably, the opening of the cavity filled with the molding powder is blocked by the tip of a powder filling device that fills the cavity with the molding powder. Before and after the filling process of filling the cavity with the molding powder, the powder filling device moves back and forth on the upper surface of the die. By making the length of the tip of the powder filling device along the above-mentioned moving direction larger than the length of the cavity along the above-mentioned moving direction, the tip of the powder filling device can block the cavity opening without any gaps during the reciprocating movement. In addition, the tip of the powder filling device can perform leveling while blocking the cavity opening, so that scattering of the molding powder during leveling can be effectively prevented.

Preferably, the powder filling device (1) closes the opening of the cavity with the tip of the powder filling device while retreating from the cavity, and (2) the die rises relative to the lower punch while the powder filling device passes over the cavity. By performing the closing step in the manner shown in (1), it is possible to smoothly transition from the filling step to the closing step, and the molding cycle can be accelerated. In addition, by performing the underfill step in the manner shown in (2), it is possible to simultaneously perform the closing step and the underfill step, and the molding cycle can be further accelerated.

Preferably, after the die has been raised relative to the lower punch, the opening of the cavity that was blocked by the tip of the powder filling device is opened. By continuing the blocking process until the underfilling process is completed in this manner, it is possible to reliably prevent the molding powder filled in the cavity from scattering outside the cavity when the underfilling process is being performed.

Furthermore, when the underfill process is completed and the die rises to the underfill completion position relative to the lower punch, a space is formed inside the cavity between the top surface of the molding powder filled in the cavity and the tip of the powder filling device that is closing the cavity opening. Because the pressure inside this space is negative compared to the outside of the cavity, when the cavity opening is opened after the underfill process is completed, air flows into the space inside the cavity. This allows the molding powder filled in the cavity to be sealed inside the cavity by the air pressure, effectively preventing it from scattering outside the cavity.

In order to achieve the above object, the powder filling apparatus according to the present invention comprises:
A powder filling apparatus for filling a cavity with molding powder, comprising:
The molding powder is supplied into a supply space, and the cup portion has an opening formed in a bottom surface thereof.
A closing portion capable of closing the cavity is provided at a tip of the cup portion located in front of the opening.

In the powder filling device according to the present invention, a closing part capable of closing the cavity is provided at the tip of the cup part located in front of the opening. Therefore, after the powder filling device fills the inside of the cavity through the opening with the molding powder supplied to the supply space, the opening of the cavity is closed by the closing part while retracting from the cavity, and the inside of the cavity is sealed. As described above, by performing the underfill process at this timing, it is possible to effectively prevent the molding powder filled in the cavity from scattering outside the cavity, and effectively prevent variations in the molding dimensions of the molded body, the occurrence of cracks or chips in the molded body, abnormal wear of the sliding parts, or a decrease in powder yield.

Preferably, the closure portion is integrated with the tip of the cup portion. For example, it is possible to configure the closure portion separately from the cup portion and detachably attach it to the tip of the cup portion, but the above configuration makes it possible to avoid the formation of a discontinuous connection between the tip of the cup portion and the closure portion, and to make the bottom surface of the closure portion flush with the top surface of the die. This allows the closure portion to close the opening of the cavity without any gaps.

Preferably, when the width of the closing portion along the movement direction of the powder filling device is W1 and the width of the cavity along the movement direction is W2, W1 ≧ W2. With this configuration, the opening of the cavity can be reliably closed by the closing portion in the movement direction of the powder filling device.

Preferably, the cup portion has a plurality of the supply spaces, the bottom surface of the cup portion has a plurality of the openings formed therein corresponding to the plurality of supply spaces, and the closure portion is provided at the tip of the cup portion located in front of the plurality of openings. With this configuration, when a plurality of cavities are formed in the die corresponding to a plurality of cup portions, the plurality of cavities can be closed with the closure portion.

In order to achieve the above object, the molding device according to the present invention has a die, a lower punch inserted into the die, and any of the powder filling devices described above. By performing an underfill process in which the opening of the cavity is blocked with the blocking portion of the powder filling device and the die is raised relative to the lower punch during this process, it is possible to effectively prevent the molding powder filled in the cavity from scattering outside the cavity, and to obtain the various effects described above.

FIG. 1 is a schematic diagram showing the configuration of a molding apparatus according to one embodiment of the present invention. FIG. 2A is a schematic side view showing the configuration of the powder filling apparatus shown in FIG. FIG. 2B is a schematic plan view of the powder filling apparatus shown in FIG. 2A. FIG. 2C is a schematic plan view of a variation of the powder filling apparatus shown in FIG. 2B. FIG. 3A is a schematic diagram showing a process for producing a molded body by the molding apparatus shown in FIG. FIG. 3B is a schematic diagram showing a step subsequent to the step shown in FIG. 3A. FIG. 3C is a schematic diagram showing a step subsequent to the step shown in FIG. 3B. FIG. 3D is a schematic diagram showing a step subsequent to the step shown in FIG. 3C. FIG. 3E is a schematic diagram showing a step subsequent to the step shown in FIG. 3D. FIG. 3F is a schematic diagram showing a step subsequent to the step shown in FIG. 3E. FIG. 3G is a schematic diagram showing a step subsequent to the step shown in FIG. 3F. FIG. 3H is a schematic diagram showing a step subsequent to the step shown in FIG. 3G. FIG. 4 is a flow chart showing the steps of manufacturing a molded body by the molding apparatus shown in FIG. FIG. 5 is a schematic diagram for explaining the effect of the present invention.

The present invention will now be described based on the embodiments shown in the drawings.

The molding device 1 according to one embodiment of the present invention shown in FIG. 1 is used to mold powder to produce a molded body of a predetermined shape, and includes a powder filling device 10, a die (mortar-shaped) 20, a lower punch 30, and an upper punch 40.

Specific examples of the molding powder include powder made of soft magnetic materials such as ferrite and metal powder. In addition to these powders, the molding powder may also contain resin. A specific example of a molded body molded by the molding device 1 is a magnetic core of a coil device. A specific example of the shape of the core is a drum core as shown in FIG. 3H. However, the type and shape of the molded body are not particularly limited, and the present invention can be applied to molded bodies of various types and shapes. In the following description, the side where the upper punch 40 is located is called the upper side, and the side where the lower punch 30 is located is called the lower side.

The die 20 has a die body 21 and a die hole 22. The die body 21 is made of a non-magnetic material, and its upper surface 21a is flat so that the powder filling device 10 can move back and forth. The die body 21 is configured to be movable up and down by a hydraulic cylinder (not shown) or the like.

The die hole 22 is a through hole that penetrates the die body 21 in the thickness direction and has a shape that corresponds to the shape of the molded body to be molded. This allows the die 20 to mold mainly the side surface of the molded body. In this embodiment, the opening shape of the die hole 22 corresponds to the planar shape of the drum core.

The lower punch 30 is attached to a lower punch base (see lower punch base 31 in FIG. 3A ) not shown, and is disposed at a position corresponding to the die hole 22. The upper end of the lower punch 30 is inserted inside the die hole 22, and is configured to be able to move freely in the vertical direction inside the die hole 22. The upper end surface 30a of the lower punch 30 has a shape corresponding to the shape of the compact to be molded, and in this embodiment, the upper end surface 30a is formed in a stepped shape corresponding to the shape of the drum core. In addition, the planar shape of the upper end surface 30a corresponds to the opening shape of the die hole 22.

A cavity 50 is formed in the area defined by the inner peripheral surface of the die hole 22 and the upper end surface 30a of the lower punch 30. The cavity 50 is filled with molding powder by the powder filling device 10, and the molding powder can be pressurized and molded inside to produce a molded body. The lower side of the cavity 50 is closed by the upper end surface 30a of the lower punch 30, while the upper side of the cavity 50 is open, forming a cavity opening 51.

The upper punch 40 is provided above the die 20 and is positioned so that it can be inserted into the cavity 50. The upper punch 40 is attached to an upper punch base (not shown), and as the upper punch base moves up and down using a hydraulic cylinder or the like, the upper punch 40 can move up and down accordingly. The upper punch 40 is inserted into the cavity 50 and, together with the lower punch 30, pressurizes and molds the molding powder filled in the cavity 50.

The lower end surface 40a of the upper punch 40 has a shape corresponding to the shape of the compact to be molded, and in this embodiment, it is formed in a stepped shape corresponding to the shape of the upper end surface 30a of the lower punch 30, i.e., the shape of the drum core. The planar shape of the lower end surface 40a corresponds to the opening shape of the die hole 22. The lower end surface 40a of the upper punch 40 and the upper end surface 30a of the lower punch 30 make it possible to mold mainly the top and bottom surfaces of the compact.

The powder filling device (feeder) 10 is used to fill the cavity 50 with molding powder, and can reciprocate along the upper surface 21a of the die 20 in the reciprocating movement direction M. More specifically, the powder filling device 10 advances (slides) to the cavity 50, fills the cavity 50 with molding powder, and then retreats from the cavity 50. As shown in Figures 2A and 2B, the powder filling device 10 has a cup portion 11, a closing portion 12, and a supply pipe 13. Hereinafter, with respect to the reciprocating movement direction M, the side where the closing portion 12 is located is referred to as the front or tip side of the powder filling device 10, and the side where the supply pipe 13 is located is referred to as the rear or base end side of the powder filling device 10.

The cup portion 11 has a supply space 15, into which a predetermined amount (fixed quantity) of molding powder is supplied from a storage hopper (not shown) via a supply pipe 13. A supply hole 14 is formed in the supply pipe 13, and the supply hole 14 is connected to the supply space 15. The size (volume) of the supply space 15 is large enough to accommodate the predetermined amount of molding powder supplied from the hopper. For example, the supply space 15 can be filled with approximately twice the amount of molding powder that can be filled into the cavity 50.

At the position of the cup portion 11, the bottom surface 10a of the powder filling device 10 is open, and an opening 16 is formed on the bottom surface of the cup portion 11. Therefore, when the cup portion 11 is positioned above the cavity 50, the molding powder supplied to the supply space 15 can be dropped through the opening 16 into the cavity 50 to fill it. The width W3 of the opening 16 along the reciprocating movement direction M is equal to or greater than the width W2 (FIG. 1) of the cavity 50 along the reciprocating movement direction M. In the illustrated example, the width of the opening 16 along the reciprocating movement direction M is equal to the width of the supply space 15 along the reciprocating movement direction M.

The closure portion 12 is integrally formed at the tip of the cup portion 11 and constitutes the tip of the powder filling device 10. The closure portion 12 is a portion of the periphery of the opening 16 that is located in front of the opening 16. The closure portion 12 has an edge portion 12a formed at the portion of the periphery of the opening 16 that is located in the front, and a tip portion 12b that is located on the opposite side to the edge portion 12a in the reciprocating movement direction M. The closure portion 12 is composed of a region that is located in front of the edge portion 12a and behind the tip portion 12b in the reciprocating movement direction M. In the illustrated example, the closure portion 12 is formed in front of the supply space 15.

When the width of the blocking portion 12 along the reciprocating movement direction M is W1 and the width of the cavity 50 (FIG. 1) along the reciprocating movement direction M is W2, in this embodiment, W1≧W2. Therefore, when the powder filling device 10 moves over the cavity 50, the blocking portion 12 can block the cavity opening 51 of the cavity 50.

In addition, by setting the widths W1 and W2 to preferably 2W2≧W1≧W2, and more preferably 1.5W2≧W1≧W2, the width W1 of the occluding portion 12 is prevented from becoming too large, and the powder filling device 10 can be made smaller. The width of the occluding portion 12 along the orthogonal direction V (FIG. 2B) perpendicular to the reciprocating movement direction M is larger than the width of the cavity 50 along the same direction, but it may be the same. In the illustrated example, the width W1 of the occluding portion 12 along the reciprocating movement direction M is smaller than the width W3 of the opening 16 along the reciprocating movement direction M, but it may be the same as or larger than the width W3.

In this embodiment, the blocking portion 12 moves (retreats) along the reciprocating movement direction M even while blocking the cavity opening 51 of the cavity 50, and blocks the cavity 50 without stopping on the cavity opening 51. Although details will be described later, by blocking the cavity 50 with the blocking portion 12, it becomes possible to prevent the molding powder filled in the cavity 50 from scattering outside the cavity 50. In other words, the blocking portion 12 functions as a leakage prevention member for the molding powder filled in the cavity 50.

At the position of the blocking portion 12, the bottom surface 10a of the powder filling device 10 is a flat surface. That is, the bottom surface 10a preferably does not have an inclined portion, a curved portion, or a bent portion. By forming such a flat surface on the bottom surface 10a, when the blocking portion 12 is placed at the cavity opening 51 of the cavity 50, the upper surface of the molding powder filled in the cavity 50 can be flattened by the blocking portion 12. Note that, when the powder filling device 10 retreats along the reciprocating movement direction M, the upper surface of the molding powder filled in the cavity 50 is flattened by the edge portion 12a of the blocking portion 12 and the bottom surface 10a at the position of the blocking portion 12 (the area from the edge portion 12a to the tip portion 12b defined by the width W1).

The width of the blocking portion 12 along the orthogonal direction V is approximately equal to the width of the cup portion 11 along the orthogonal direction V. The blocking portion 12 may be formed locally, for example, only at a position corresponding to the opening 16 or the supply space 15. In this case, the width of the blocking portion 12 along the orthogonal direction V may be approximately equal to the width of the opening 16 along the orthogonal direction V, and the blocking portion 12 may be formed so as to protrude from the tip of the cup portion 11 toward the tip in the reciprocating movement direction M.

The powder filling device 10, die 20, lower punch 30, and upper punch 40 are each connected to a control unit (not shown) via a communication line, and can operate upon receiving a control signal transmitted from the control unit. The control unit performs control to enable the molding device 1 to execute each step shown in FIG. 4.

Below, with reference to Figures 3A to 3H and 4, a molding method for molding the molding powder inside the cavity 50 will be described. As shown in Figure 3A, first, at a position a predetermined distance back from the cavity 50, a certain amount of molding powder 60 is supplied from a hopper (not shown) to the cup portion 11 (supply space 15) of the powder filling device 10 via the supply pipe 13 at a position. At this time, since the opening 16 is closed by the upper surface 21a of the die 20, the supply space 15 is filled with the certain amount of molding powder 60 supplied. In addition, a lower punch 30 is inserted inside the die hole 22 of the die 20 to form a cavity 50.

When the supply of the molding powder to the supply space 15 is completed, the powder filling device 10 starts moving (advancing) from a position a predetermined distance back from the cavity 50 along the forward direction M1 on the upper surface 21a of the die 20 toward the cavity 50. Then, as shown in FIG. 3B, when the powder filling device 10 reaches the cavity 50 and the opening 16 of the cup portion 11 is positioned above the cavity opening 51 of the cavity 50, the opening 16 of the cup portion 11 is opened, and the molding powder 60 contained in the supply space 15 falls by gravity through the opening 16 and is filled into the cavity 50 (FIG. 4: step S1).

The amount of molding powder 60 supplied to the supply space 15 is greater than the amount of molding powder 60 that can be filled into the cavity 50, so as shown in FIG. 3B, when the cavity 50 is filled with molding powder 60, some of the molding powder 60 that did not fit into the cavity 50 remains in the supply space 15.

In this state, as shown in FIG. 3C, the powder filling device 10 starts to move (retreat) the upper surface 21a of the die 20 in a direction away from the cavity 50 along the retraction direction M2. At this time, the opening 16 of the powder filling device 10 moves away from the cavity opening 51 along the retraction direction M2, while the closing portion 12 of the powder filling device 10 moves closer to the cavity opening 51 along the retraction direction M2.

Then, when the edge portion 12a of the blocking portion 12 reaches the portion of the opening edge of the cavity opening 51 that is located rearward in the retreating direction M2 while the powder filling device 10 is retreating from the cavity 50, the blocking portion 12 completely blocks the cavity opening 51 of the cavity 50 that is filled with the molding powder 60 (Figure 4: step S2).

This blocking state of the cavity opening 51 by the blocking part 12 continues until the powder filling device 10 continues to recede along the upper surface 21a of the die 20 and the tip 12b of the blocking part 12 reaches the part of the opening edge of the cavity opening 51 that is located forward in the receding direction M2. When the cavity opening 51 is completely blocked by the blocking part 12, the opening 16 is completely blocked by the upper surface 21a of the die 20.

In the process of the closing portion 12 passing over the cavity opening 51, the surface (upper surface) of the molding powder 60 filled in the cavity 50 is uniformly leveled and flattened at the cavity opening 51 by what is called leveling. This leveling is mainly performed by the edge portion 12a of the closing portion 12. Therefore, the upper surface of the molding powder 60 becomes approximately flush with the upper surface 21a of the die 20 that defines the cavity opening 51. In order to obtain the effect of leveling the upper surface of the molding powder 60 filled in the cavity 50, it is preferable that the closing portion 12 has a certain degree of mechanical strength, and the powder filling device 10 including the closing portion 12 is preferably made of a high-strength material such as stainless steel.

In addition, when the cavity opening 51 is completely blocked (covered) by the blocking portion 12, the upper surface of the molding powder 60 filled in the cavity 50 is uniformly pressed overall by the bottom surface of the blocking portion 12. Therefore, the molding powder 60 is uniformly filled in the cavity 50, and the filling density of the molding powder 60 in the cavity 50 is uniform. Therefore, density variation and weight variation of the molding powder 60 in the cavity 50 can be prevented.

As shown in FIG. 3D, in this embodiment, while the blocking portion 12 is blocking the cavity opening 51, an underfilling process (FIG. 4: step S3) is performed in which the die body 21 of the die 20 is raised a predetermined distance (for example, 0.5 to 1.5 mm) relative to the lower punch 30 along the upward direction M3. The underfilling process is started when the blocking portion 12 completely blocks the cavity opening 51 (when the edge portion 12a reaches the portion of the opening edge of the cavity opening 51 located behind in the retreating direction M2). This underfilling process causes the upper surface 21a of the die 20 to gradually rise relative to the lower punch 30, and is finally positioned at a position (underfilling completion position) a predetermined distance above the upper surface of the molding powder 60 filled in the cavity 50. As a result, a gap 70 having a height according to the rising distance of the die body 21 is formed in the cavity 50 between the upper surface of the molding powder 60 filled in the cavity 50 and the bottom surface (bottom surface 10a) of the blocking portion 12.

In this embodiment, during the underfill process, from the time when the die body 21 starts to move upward relative to the lower punch 30 until the time when the die body 21 reaches the underfill completion position, the blocking portion 12 moves in the backward direction M2 while maintaining the cavity opening 51 blocked. Therefore, during the underfill process, the gap 70 is not opened, and the cavity 50 is kept sealed.

In the underfill process, the powder filling device 10 does not stop moving backward along the backward direction M2 above the cavity 50, but passes (backs) above the cavity 50 in the backward direction M2. During this backward movement by the powder filling device 10, the die body 21 rises relative to the lower punch 30. That is, in this embodiment, the upward movement of the die body 21 along the upward direction M3 and the backward movement of the powder filling device 10 along the backward direction M2 are performed simultaneously. This allows the powder filling device 10 to quickly return to the backward completion position, thereby speeding up the molding cycle or molding tact.

When the moving speed of the powder filling device 10 when it is retreating is v and the time required from the start to the completion of the underfilling process is t, it is preferable that the width W1 (Fig. 2A) of the blocking portion 12 is a length that corresponds (proportional) to the sum (W2+vt) of the width W2 (Fig. 1) of the cavity opening 51 and the product (vt) of the moving speed v and the time t. This allows the cavity opening 51 to be kept blocked by the blocking portion 12 while the powder filling device 10 is retreating in the retreat direction M2.

After the die body 21 reaches the underfill completion position and the rise of the die body 21 relative to the lower punch 30 is completed, as shown in FIG. 3E, the cavity opening 51 is unblocked by the blocking portion 12, and the cavity opening 51 gradually opens. That is, the operations of the powder filling device 10 and the die body 21 are controlled so that, at the point when the die body 21 reaches the underfill completion position, the tip portion 12b of the blocking portion 12 passes along the retreat direction M2, a portion of the opening edge of the cavity opening 51 that is located forward in the retreat direction M2.

As a result, the gap 70 communicates with the external space through the cavity opening 51. At this time, the inside of the cavity 50 is at negative pressure relative to the external space (pressure is reduced), so air flows from the external space toward the gap 70, as shown by arrow A. The air pressure caused by the air (airflow) flowing into this gap 70 acts to press the molding powder 60 filled in the cavity 50 toward the inside of the cavity 50.

When the powder filling device 10 returns to a position a predetermined distance away from the cavity 50 (retraction completion position), the upper punch 40 descends along the descending direction M4 as shown in FIG. 3F. Also, as shown in FIG. 3G, the upper punch 40 is inserted into the cavity 50 and descends to the pressurization completion position. Then, at this pressurization completion position, the molding powder 60 filled in the cavity 50 is pressurized (compressed) (FIG. 4: step S4). This produces a molded body 80 having a shape corresponding to the shapes of the upper end surface 30a of the lower punch 30, the lower end surface 40a of the upper punch 40, and the die hole 22.

Then, as shown in FIG. 3H, the upper punch 40 moves upward along the upward direction M3 and waits above the lower punch 30. At the same time, or thereafter, the die body 21 moves downward along the downward direction M4 until the position of the upper surface 21a of the die 20 and the position of the upper end surface 30a of the lower punch 30 are substantially aligned. The distance of descent at this time corresponds to the sum of the height of the compact 80 and the height of the gap 70. In this way, the compact 80 is pushed up from within the cavity 50 to the position of the upper surface 21a of the die 20 and ejected from the cavity 50 (FIG. 4: step S5).

In this way, a series of molding cycles from step S1 to step S5 is completed, and thereafter, this molding cycle is executed repeatedly to produce a large number of molded bodies 80. The generated molded bodies 80 may be subjected to processing such as sintering as necessary.

As shown in FIG. 3D, the underfill process is performed by raising the die body 21 relative to the lower punch 30 along the upward direction M3, but it may also be performed, for example, by lowering the lower punch 30 relative to the die body 21. As shown in FIG. 3H, the ejection process is performed by lowering the die body 21 along the downward direction M, but it may also be performed, for example, by raising the lower punch 30 relative to the die body 21.

In the molding method according to this embodiment, the closing step shown in FIG. 3C is performed prior to the underfill step shown in FIG. 3D, and the underfill step is performed with the cavity opening 51 closed. Therefore, when the underfill step is performed, the inside of the cavity 50 is sealed, and even if the molding cycle is performed at high speed, the molding powder 60 filled in the cavity 50 can be effectively prevented from scattering outside the cavity 50. In addition, after the underfill step is completed, the upper surface of the molding powder 60 filled in the cavity 50 is positioned lower than the upper surface 21a of the die 20 that defines the cavity opening 51, and the molding powder 60 can be prevented from scattering outside the cavity 50.

Figure 5 is a trace of a photograph of the upper surface 21a of the die 20 viewed from above with the molded body 80 placed in the cavity 50 before the ejection process shown in Figure 3H is performed. In Figure 5, the diagram shown at the bottom of the page shows the state of the upper surface 21a when the present invention is applied to the molding device 1, and the diagram shown at the top of the page shows the state of the upper surface 21a when the present invention is not applied to the molding device 1.

As can be seen from the drawings, when the present invention is not applied to the molding device 1, molding powder 60 is scattered around the cavity opening 51 on the upper surface 21a of the die 20, but when the present invention is applied to the molding device 1, there is almost no scattering of molding powder 60 around the cavity opening 51 on the upper surface 21a of the die 20. In this way, according to this embodiment, it is possible to effectively prevent the molding powder 60 from scattering outside the cavity 50.

In addition, in this embodiment, scattering of the molding powder 60 is prevented, so that the amount of molding powder 60 filled into the cavity 50 can be kept constant, and the molding powder 60 can be uniformly filled into the cavity 50. Therefore, even for small molded bodies 80 (Figure 3H), it is possible to prevent variations in the molding dimensions of the molded body 80, make the molded body density uniform, and prevent cracks and chips from occurring in the molded body 80.

The molding device 1 may be equipped with a sliding part for raising and lowering the die body 21 during the underfill process, etc., and by preventing the molding powder 60 from scattering, it is possible to prevent problems such as the molding powder 60 getting into the sliding part and causing abnormal wear. As a result, the number of maintenance operations for the molding device 1 can be reduced.

In addition, by preventing scattering of the molding powder 60, the ratio (powder yield) of the net molding powder 60 that is actually used to mold the molded body 80 within the cavity 50 out of the molding powder 60 filled within the cavity 50 can be increased.

In the powder filling apparatus 10 according to this embodiment, as shown in FIG. 2A, a closing part 12 capable of closing the cavity 50 is provided at the tip of the cup part 11 located in front of the opening 16, and the closing part 12 closes the cavity opening 51 of the cavity 50 filled with the molding powder 60. Therefore, before and after the filling process shown in FIG. 3B, the closing part 12 can close the cavity opening 51 without any gaps while the powder filling apparatus 10 moves back and forth on the upper surface 21a of the die 20. In particular, in this embodiment, the powder filling apparatus 10 fills the cavity 50 with the molding powder 60 supplied to the supply space 15 through the opening 16, and then closes the cavity opening 51 with the closing part 12 while retreating from the cavity 50, thereby sealing the inside of the cavity 50.

In addition, in this embodiment, the closing portion 12 can close the cavity opening 51 while performing the leveling process, so that scattering of the molding powder 60 during the leveling process can be effectively prevented.

In addition, in this embodiment, the powder filling apparatus 10 (1) closes the cavity opening 51 with the closing portion 12 while retreating from the cavity 50 (cavity opening 51) as shown in FIG. 3C, and (2) the die body 21 rises relative to the lower punch 30 while the powder filling apparatus 10 passes over the cavity 50 as shown in FIG. 3D. By performing the closing process as shown in (1), it is possible to smoothly transition from the filling process to the closing process, and the molding cycle can be accelerated. Also, by performing the underfill process as shown in (2), it is possible to simultaneously perform the closing process and the underfill process, and the molding cycle can be further accelerated.

In addition, in this embodiment, after the die body 21 has completed rising relative to the lower punch 30 as shown in FIG. 3E, the cavity opening 51 that was blocked by the blocking portion 12 is opened. By continuing the blocking process until the underfilling process is completed in this manner, it is possible to reliably prevent the molding powder 60 filled in the cavity 50 from scattering outside the cavity 50 when the underfilling process is being performed.

When the underfill process is completed and the die body 21 rises to the underfill completion position relative to the lower punch 30, a space 70 is formed inside the cavity 50 between the upper surface of the molding powder filled in the cavity 50 and the blocking portion 12 blocking the cavity opening 51. Since the space 70 is at a negative pressure compared to the outside of the cavity 50, air flows into the space 70 when the opening of the cavity 50 is opened after the underfill process is completed. As a result, the molding powder 60 filled in the cavity 50 is sealed inside the cavity 50 by the air pressure, and it is possible to effectively prevent it from scattering outside the cavity 50.

In addition, in this embodiment, as shown in FIG. 2A, the closure portion 12 is integrated with the tip of the cup portion 11. For example, it is possible to configure the closure portion 12 separately from the cup portion 11 and detachably attach it to the tip of the cup portion 11, but the above configuration makes it possible to avoid the formation of a discontinuous connection between the tip of the cup portion 11 and the closure portion 12, and to make the bottom surface of the closure portion 12 and the upper surface 21a of the die 20 flush with each other. This allows the closure portion 12 to close the cavity opening 51 without any gaps.

In addition, in this embodiment, the width W1 of the closure portion 12 along the reciprocating movement direction M of the powder filling device 10 and the width W2 of the cavity 50 along the reciprocating movement direction M1 are W1 ≧ W2. Therefore, the cavity opening 51 can be reliably closed by the closure portion 12 along the reciprocating movement direction M1 of the powder filling device 10.

The present invention is not limited to the above-described embodiment, and can be modified in various ways within the scope of the present invention.

In the above embodiment, as shown in FIG. 2B, the powder filling apparatus 10 has one supply space 15 and one supply pipe 13, but as shown in FIG. 2C, the powder filling apparatus 10' may have multiple supply spaces 15 and multiple supply pipes 13. In the example shown in FIG. 2C, the cup portion 11' has multiple supply spaces 15, and multiple openings 16 are formed in the bottom surface of the cup portion 11' corresponding to the multiple supply spaces 15. In addition, a blocking portion 12' is provided at the tip of the cup portion 11' located in front of the multiple openings 16. The blocking portion 12' is formed in the tip of the cup portion 11' in a region extending from one end to the other end in the orthogonal direction V. With this configuration, when multiple cavities 50 (not shown) are formed in the die body 21 corresponding to the multiple cup portions 11', these multiple cavities 50 can be blocked by the blocking portion 12'.

In this case, the tip of the cup portion 11' may be locally provided with a plurality of blocking portions 12' corresponding to the plurality of openings 16. This configuration makes it possible to locally form a plurality of blocking portions 12' at the tip of the cup portion 11', and prevents the powder filling device 10' from becoming larger due to the addition of the blocking portions 12' to the cup portion 11'.

In the example shown in FIG. 2C, the number of supply pipes 13 is equal to the number of supply spaces 15, but the molding powder 60 may be supplied to each supply space 15 using one supply pipe 13.

In the above embodiment, as shown in FIG. 3D, in the underfilling process, the die body 21 rises relative to the lower punch 30 while the powder filling device 10 is retracting above the cavity 50 in the retracting direction M2. However, when the die body 21 rises relative to the lower punch 30, the powder filling device 10 may stop moving in the retracting direction M2 above the cavity 50. In other words, the powder filling device 10 may start moving in the retracting direction M2 when the underfilling process is completed.

In addition, during the underfill process, it is preferable that the blocking portion 12 maintains the cavity opening 51 blocked from the time when the die body 21 starts to move upward relative to the lower punch 30 until the die body 21 reaches the underfill completion position, but the blocking portion 12 may slightly open the cavity opening 51 before the die body 21 reaches the underfill completion position.

DESCRIPTION OF SYMBOLS 1... Molding apparatus 10, 10'... Powder filling apparatus 10a... Bottom surface 11, 11'... Cup portion 12, 12'... Closing portion 12a... Edge portion 12b... Tip portion 13... Supply pipe 14... Supply hole 15... Supply space 16... Opening 20... Die 21... Die body 21a... Upper surface 22... Die hole 30... Lower punch 30a... Upper end surface 31... Lower punch base 40... Upper punch 40a... Lower end surface 50... Cavity 51... Cavity opening 60... Powder for molding 70... Gap 80... Molded body

Claims (7)

A molding method for molding a molding powder inside a cavity formed by inserting a lower punch into a die, comprising the steps of:
filling the cavity with molding powder;
a step of closing an opening of the cavity filled with molding powder;
and a step of raising the die relative to the lower punch while closing the opening of the cavity,
The molding method includes closing an opening of the cavity filled with molding powder with a tip of a powder filling device that fills the cavity with the molding powder . the powder filling device closes an opening of the cavity with a tip end of the powder filling device while retracting from the cavity;
2. The method of claim 1 , wherein the die is raised relative to the lower punch while the powder filling device is passing over the cavity. 3. The molding method according to claim 1 , wherein the opening of the cavity that has been closed by the tip of the powder filling device is opened after the rise of the die relative to the lower punch is completed. A powder filling apparatus for filling a cavity with molding powder, comprising:
The molding powder is supplied into a supply space, and the cup portion has an opening formed in a bottom surface thereof.
a closing portion capable of closing the cavity is provided at a tip portion of the cup portion located in front of the opening ,
The cup portion includes a plurality of the supply spaces,
A plurality of the openings are formed in a bottom surface of the cup portion corresponding to a plurality of supply spaces,
A powder filling device , wherein the closing portion is provided at a tip of the cup portion located in front of the plurality of openings . 5. The powder filling apparatus according to claim 4 , wherein the closing portion is integral with the tip of the cup portion. 6. The powder filling apparatus according to claim 5, wherein W1 is a width of the closing portion along a moving direction of the powder filling apparatus, and W2 is a width of the cavity along the moving direction, and W1 is greater than or equal to W2. Die and
A lower punch inserted into the die;
A molding apparatus comprising the powder filling apparatus according to any one of claims 4 to 6 .

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