POWDER MOLDING APPARATUS AND COMPACT MANUFACTURING METHOD

Abstract

Provided is a powder molding apparatus including: a die; an upper punch and a lower punch; a middle platen attached to the upper punch; an upper platen mounted on a press machine and the upper platen being attached to a push rod; a link mechanism connecting the upper platen and the middle platen; a first actuator that fixes the link mechanism and cancels a fixation of the link mechanism; a bolster attached to the lower punch, and a lower platen attached to the die, in which descending of the upper platen and the push rod causes the lower platen and the die to be pushed downward by the push rod, and along with a downward movement of the die, the lower punch makes a upward movement inside the hollow with respect to the die.

Description

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2015-185134 filed on Sep. 18, 2015 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a powder molding apparatus and a compact manufacturing method using the apparatus.

2. Description of Related Art

various types of sintered parts are manufactured by press-molding metal powder into a compact and sintering the compact.

In the aforementioned press molding, using a powder molding apparatus including a die having a hollow and an upper punch and a lower punch that slide inside the hollow of the die and form a cavity jointly with the hollow, a metal powder body is charged into the cavity and is pressurized by pushing down, for example, the upper punch, whereby a powder compact is manufactured.

Japanese Patent Application Publication No. 6-188138 discloses a molding apparatus in which when a compact is ejected from a die, the die is pulled down using an actuator provided below the die, and molding apparatuses of this type are in common use.

Employment of the molding apparatus disclosed in JP 6-188138 A requires providing an actuator and a mechanism (e.g., a rod) that connects the actuator and the die below the die, causing a problem in that a position of the die from the ground is often high.

Also, for the convenience of work, the height of the die needs to be a height that allows an upper surface of the die to be viewed by a worker, and thus, a problem also arises in that it is necessary to dig a pit at a site where a press is to be installed to embed a lower portion of the press under the ground or it is necessary for the worker to stand on a platform and perform work.

Furthermore, in ejection of a compact from the die, in order to prevent cracking of the compact, it is necessary to apply a hold-down load (the compact is ejected from the die in a state in which the compact is held between the lower punch and the upper punch and a load for the holding the compact in this situation is referred to as “hold-down load”).

In order to keep the hold-down load constant, it is necessary to provide a load cell to perform control; however, the load cell needs to withstand not only the hold-down load, but also a molding load, resulting in problems in that the molding apparatus itself tends to large in size and is often expensive.

SUMMARY OF THE INVENTION

The present invention provides a powder molding apparatus that enables a manufactured compact to be ejected easily without the need to make a height of the molding apparatus to be high and the need to dig a pit at a site where a press is to be installed and, and a compact manufacturing method using the apparatus.

A powder molding apparatus according to an aspect of the present invention includes: a die having a hollow; an upper punch and a lower punch that slide inside the hollow of the die and form a cavity jointly with an inner wall of the hollow; a middle platen attached to the upper punch; an upper platen attached to a push rod; a press machine that pushes down the upper platen; a link mechanism that connects the upper platen and the middle platen; a first actuator that fixes the link mechanism and cancels the fixation of the link mechanism; a bolster attached to the lower punch; and a lower platen attached to the die, the lower platen being biased upward from the bolster via a spring, and descending of the upper platen and the push rod causes the lower platen and the die to be pushed downward by the push rod, and along with a downward movement of the die, the lower punch makes a upward movement inside the hollow with respect to the die.

The powder molding apparatus according to the aspect of the present invention employs the configuration in which the first actuator fixes, and cancels the fixation of, a link mechanism connecting the upper platen attached to the push rod (injection push rod), the push rod pushing down the lower platen equipped with the die, and the middle platen equipped with the upper punch that slides inside the die.

At the time of molding for press-molding powder charged in the cavity, the link mechanism is fixed by the first actuator, a pressing force from the press machine is transmitted to the upper platen, the pressing force is transmitted to the middle platen via the fixed link mechanism, and the pressing force is then transmitted to the upper punch provided on the middle platen, whereby the powder is press-molded.

On the other hand, when a molded compact is ejected from the cavity, the first actuator cancels the fixation of the link mechanism, and the pressing force from the press machine is transmitted to the upper platen, but the pressing force is not transmitted to the middle platen via the unfixed link mechanism.

Instead, the pressing force transmitted to the upper platen is transmitted to the lower platen equipped with the die by the push rod, whereby the lower platen and the die are pushed down. As a result of the die being pushed down, the compact molded on the lower punch inside the hollow of the die is exposed above the die, enabling ejection of the compact.

Examples of the first actuator can include, e.g., an air cylinder mechanism and an oil hydraulic cylinder mechanism.

Also, examples of the press machine can include a slide and a unit body including an oil hydraulic cylinder or the like and a slide.

According to the powder molding apparatus according to the aspect of the present invention, in molding of powder and ejection of a compact, fixation and cancellation of the fixation of a link mechanism are performed, respectively, by the first actuator, enabling the manufactured compact to be easily ejected without the need to make a height of the molding apparatus to be high and the need to dig a pit at a site where the press is installed.

In the powder molding apparatus according to the aspect of the present invention, the link mechanism may include two links and three joints, the three joints connecting the links, the upper platen and the middle platen, respectively, and connecting the two links.

In the powder molding apparatus according to the aspect of the present invention, the first actuator may include an air cylinder and a piston, and a distal end of the piston may be attached to the joint that is a middle joint among the three joints.

Also, the powder molding apparatus according to the aspect of the present invention may further include a second actuator between the upper platen and the middle platen.

As with the first actuator, the second actuator includes, e.g., an air cylinder mechanism or an oil hydraulic cylinder mechanism.

After a compact is molded in the cavity, the fixation of the link mechanism is cancelled by the first actuator, and a pressing force from the press machine is thus transmitted to the lower platen equipped with the die, via the push rod to push the lower platen and the die down. Here, if the second actuator is not provided, no pressing force is applied to the upper punch, but because of the provision of the second actuator, the die can be pushed down while the compact being pressed by the second actuator with a pressing force that is smaller than a pressing force applied at the time of the molding.

In the second actuator, for example, a relief valve is provided, enabling a compact to be pressed while a load applied on the upper punch (what is called “hold-down load”) being kept constant by the second actuator, and also a pressing force from the press machine to be transmitted to the lower platen equipped with the die, by the push rod to push the lower platen and the die down, whereby the compact is exposed from the cavity.

Also, the aspect of the present invention also provides a compact manufacturing method, and the manufacturing method is a compact manufacturing method using the above powder molding apparatus, the method including: charging powder into the cavity; manufacturing a compact by fixing the link mechanism via the first actuator, and pushing down the upper platen, the middle platen and the upper punch via the press machine to mold the powder in the cavity; cancelling the fixation of the link mechanism via the first actuator, pushing down the upper platen via the press machine, and pushing down the lower platen and the die via the push rod to expose the compact from the cavity.

The manufacturing method according to the aspect of the present invention employs the powder molding apparatus according to the aspect of the present invention, enabling manufacture of a compact and ejection of the manufactured compact from the cavity to be performed easily.

Also, during exposure of the compact from the cavity, a first pressing force (hold-down load) is applied from the second actuator to the upper punch to expose the compact from the cavity while the compact being pressed by the first pressing force, the first pressing force being lower than a second pressing force applied to push down the upper platen, the middle platen and the upper punch via the press machine to mold the powder in the cavity.

As can be understood from the above statement, with the powder molding apparatus according to the aspect of the present invention and the compact manufacturing method according to the aspect of the present invention, in molding of powder and ejection of a compact, fixation and cancellation of the fixation of the link mechanism are performed, respectively, by the first actuator, enabling the manufactured compact to be easily ejected without the need to make a height of the molding apparatus to be high and the need to dig a pit at a site where the press is installed.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a schematic diagram of Embodiment 1 of a powder molding apparatus according to an aspect of the present invention;

FIG. 2 is a schematic diagram illustrating a state in which a compact is being manufactured in Embodiment 1 of the powder molding apparatus;

FIG. 3 is a schematic diagram illustrating a state in which a compact is exposed from a cavity so that the compact can be ejected in Embodiment 1 of the powder molding apparatus;

FIG. 4 is a schematic diagram of Embodiment 2 of the powder molding apparatus;

FIG. 5 is a schematic diagram illustrating a state in which a compact is being manufactured in Embodiment 2 of the powder molding apparatus;

FIG. 6 is a schematic diagram illustrating a state in which a compact is exposed from a cavity in Embodiment 2 of the powder molding apparatus; and

FIG. 7 is a schematic diagram illustrating a state in which the compact is exposed from the cavity so that the compact can be ejected in Embodiment 2 of the powder molding apparatus.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments 1 and 2 of a powder molding apparatus according to the present invention and compact manufacturing methods will be described below with reference to the drawings.

(Embodiment 1 of powder molding apparatus and compact manufacturing method) FIG. 1 is a schematic diagram of Embodiment 1 of a powder molding apparatus according to the present invention, FIG. 2 is a schematic diagram illustrating a state in which a compact is being manufactured in Embodiment 1 of the powder molding apparatus, and FIG. 3 is a schematic diagram illustrating a state in which the compact is exposed from a cavity so that the compact can be ejected in Embodiment 1 of the powder molding apparatus.

The illustrated powder molding apparatus 200 roughly includes a press machine 70 installed in a frame 100, a die 10, an upper punch 20 and a lower punch 30, a middle platen 50 with the upper punch 20 attached thereto, an upper platen 40, a link mechanism 90 connecting the upper platen 40 and the middle platen 50, a first actuator 80 that fixes and cancels the fixation of the link mechanism 90, a bolster 61 with the lower punch 30 attached thereto, and a lower platen 60 with the die 10 attached thereto.

The lower punch 30 and the upper punch 20 are slidable inside a hollow 11 of the die 10, and in FIG. 1, metal powder F to be press-molded is charged in a cavity defined by the hollow 11 and the lower punch 30.

The upper punch 20 is attached to a lower surface of the middle platen 50 via a retainer 53, and first guide posts 54 are attached to an upper surface of the middle platen 50.

Also, a stopper 51 that holds a fixed position of the link mechanism 90 and a first actuator attachment portion 52 are provided on the upper surface of the middle platen 50.

First guide bushes 40a through which the respective first guide posts 54 extend are provided in the upper platen 40, a slider 72 included in the press machine 70 is mounted on an upper surface of the upper platen 40, and push rods 41 are attached to a lower surface of the upper platen 40.

The lower punch 30 is attached to an upper surface of the bolster 61 via a retainer 63, and second guide posts 62 are also attached to the upper surface of the bolster 61.

Second guide bushes 60a through which the second guide posts 62 extend are provided in the lower platen 60, and the die 10 is attached at the center of the lower platen 60.

A spring 64 is disposed around a periphery of each second guide post 62 projecting from the upper surface of the bolster 61, and the springs 64 support the lower platen 60 while biasing the lower platen 60 upward.

The press machine 70 includes an oil hydraulic cylinder 71 that slides a piston 71a, and a slider 72 that receives a pressing force from the piston 71a.

The components of the powder molding apparatus 200 are housed in the frame 100, and the oil hydraulic cylinder 71 included in the press machine 70 is fixed on a top surface of the frame, and the piston 71a extends through the top surface and projects to the inside of the frame 100, and a distal end of the piston 71a is fixed to the slider 72.

The link mechanism 90 includes two links 91 and three joints 92, the three joints 92 connecting the links 91 to the upper platen 40 and the middle platen 50, respectively, and connecting the two links 91 to each other.

The first actuator 80 includes an air cylinder 81 and a piston 82, and a distal end of the piston 82 is attached to the joint 92 that is a middle joint among the three joints 92.

FIG. 1 illustrates a state in which the piston 82 has moved to a left end of the air cylinder 81 (Z1 direction) and fixes the two links 91, 91 linearly.

As illustrated in FIG. 1, metal powder F is charged in the cavity, and the link mechanism 90 is fixed linearly by the first actuator 80, and then, as illustrated in FIG. 2, the press machine 70 is activated to slide the piston 71a to provide a pressing force P to the upper platen 40 via the slider 72.

Upon receipt of the pressing force P, the upper platen 40 pushes down the middle platen 50 and the upper punch 20 fixed to the lower surface of the middle platen 50 (X1 direction) via the link mechanism 90 fixed linearly by the first actuator 80, and the metal powder F is molded in the cavity defined by the die 10 and the lower punch 30, whereby a compact C is manufactured.

After the manufacture of the compact C, next, the compact C is ejected from the cavity.

More specifically, as illustrated in FIG. 3, the piston 82 moves rightward inside the air cylinder 81 of the first actuator 80 (Z2 direction) to pivot the two links 91, 91 included in the link mechanism 90 around the respective joints 92 (respective Y1 directions), whereby the linear fixation of the link mechanism 90 is cancelled.

Upon the press machine 70 being activated (pressing force P′) concurrently with the cancellation of the fixation of the link mechanism 90, the lower platen 60 and the die 10 are pushed down against the biasing force from the spring 64, via the push rods 41 (X2 direction) while the pressing of the compact C by the upper punch 20 being cancelled.

As a result of the die 10 being pushed down, the compact C in the cavity moves upward relative to the die 10 (X3 direction) and the compact C is then exposed to the outside of the cavity and the compact C can thus be ejected.

As described above, according to the powder molding apparatus 200, in molding of metal powder F and ejection of a compact C, fixation and cancellation of the fixation of the link mechanism 90 are performed, respectively, by the first actuator 80, enabling a manufactured compact to be easily ejected without the need to make a height of the powder molding apparatus 200 to be high and the need to dig a pit at a site where the press is installed.

(Embodiment 2 of powder molding apparatus and compact manufacturing method) FIG. 4 is a schematic diagram of Embodiment 2 of the powder molding apparatus, and FIG. 5 is a schematic diagram illustrating a state in which a compact is being manufactured in Embodiment 2 of the powder molding apparatus. Also, FIG. 6 is a schematic diagram illustrating a state in which the compact is exposed from a cavity in Embodiment 2 of the powder molding apparatus, and FIG. 7 is a schematic diagram illustrating a state in which the compact is exposed from the cavity so that the compact can be ejected in Embodiment 2 of the powder molding apparatus.

A powder molding apparatus 200A, which is illustrated in FIG. 4, is an apparatus obtained by adding two second actuators 80A connecting the upper platen 40 and the middle platen 50 to the powder molding apparatus 200.

As illustrated in FIG. 4, the two second actuators 80A each include an air cylinder 81A and a piston 82A, and is disposed in such a manner that the piston 82A moves up/down vertically.

In each of the second actuators 80A, a non-illustrated relief valve is provided, whereby a compact C is pressed while a load applied on an upper punch 20 (what is called “hold-down load”) being kept constant by the second actuators 80A (see FIG. 6), and a pressing force from a press machine 70 is transmitted to a lower platen 60 equipped with a die 10 by push rods 41, thereby the compact C being exposed to the outside of the cavity.

In other words, the second actuators 80A are actuators for applying a constant hold-down load to a compact C when the compact C is ejected.

Here, a compact manufacturing method using the powder molding apparatus 200A will generally be described.

As illustrated in FIG. 5, the press machine 70 is activated to apply a pressing force P to a middle platen 50 and the upper punch 20 fixed to a lower surface of the middle platen 50 via a link mechanism 90 fixed linearly by the first actuator 80 to push down the middle platen 50 and the upper punch 20 (X1 direction), whereby a compact C is manufactured in the cavity defined by the die 10 and a lower punch 30.

Next, as illustrated in FIG. 6, a piston 82 is moved rightward (Z2 direction) inside an air cylinder 81 of the first actuator 80 to pivot two links 91, 91 included in the link mechanism 90 around respective joints 92 (respective Y1 directions), whereby the linear fixation of the link mechanism 90 is cancelled.

Furthermore, the pistons 82A are moved upward inside the air cylinders 81A of the respective second actuators 80A (Z3 direction) to apply a constant hold-down load from the second actuators 80A to the middle platen 50 (X4 direction) and apply the constant hold-down load to the upper punch 20 via the middle platen 50 (X5 direction).

With the compact C held by the constant hold-down load, a pressing force V from the press machine 70 pushes down the lower platen 60 and the die 10 against a biasing force of the spring 64, via the push rods 41 (X2 direction).

As illustrated in FIG. 6, as a result of the die 10 being pushed down, the compact C in the cavity moves upward relative to the die 10 (X3 direction).

As illustrated in FIG. 7, the pistons 82A are moved further upward inside the air cylinders 81A of the respective second actuators 80A (Z4 direction) to move the middle platen 50 and the upper punch 20 upward (X6 direction), whereby the compact C exposed to the outside of the cavity can be ejected.

In addition to the effects provided when the powder molding apparatus 200 is used, the powder molding apparatus 200A can prevent a compact C from cracking when the compact C is ejected from the die 10.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configurations are not limited to those of these embodiments, and alternations in design and the like of such specific configurations without departing from the spirit of the present invention also fall within the scope of the present invention.

Claims

1. A powder molding apparatus comprising:

a die having a hollow;

an upper punch and a lower punch that slide inside the hollow of the die and form a cavity jointly with an inner wall of the hollow;

a middle platen attached to the upper punch;

an upper platen attached to a push rod;

a press machine that pushes down the upper platen;

a link mechanism that connects the upper platen and the middle platen;

a first actuator that fixes the link mechanism and cancels a fixation of the link mechanism;

a bolster attached to the lower punch; and

a lower platen attached to the die, the lower platen being biased upward from the bolster via a spring, wherein

descending of the upper platen and the push rod causes the lower platen and the die to be pushed downward by the push rod, and along with a downward movement of the die, the lower punch makes a upward movement inside the hollow with respect to the die.

2. The powder molding apparatus according to claim 1, wherein

the link mechanism includes two links and three joints, the three joints connecting the links, the upper platen and the middle platen, respectively, and connecting the two links.

3. The powder molding apparatus according to claim 2, wherein

the first actuator includes an air cylinder and a piston, and a distal end of the piston is attached to the joint that is a middle joint among the three joints.

4. The powder molding apparatus according to claim 1, further comprising a second actuator between the upper platen and the middle platen.

5. The powder molding apparatus according to claim 4, wherein

a relief valve is provided in the second actuator.

6. A compact manufacturing method using the powder molding apparatus according to claim 1, the method comprising:

charging powder into the cavity;

manufacturing a compact by fixing the link mechanism via the first actuator, and pushing down the upper platen, the middle platen and the upper punch via the press machine to mold the powder in the cavity;

cancelling the fixation of the link mechanism via the first actuator, pushing down the upper platen via the press machine, and pushing down the lower platen and the die via the push rod to expose the compact from the cavity.

7. The compact manufacturing method according to claim 6, wherein

the powder molding apparatus according to claim 4 is used,

during exposure of the compact from the cavity, a first pressing force is applied from the second actuator to the upper punch to expose the compact from the cavity while the compact being pressed by the first pressing force, the first pressing force being lower than a second pressing force applied to push down the upper platen, the middle platen and the upper punch via the press machine to mold the powder in the cavity.