JPH09194903A - Molding method of powder molding having undercut part and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for molding a powder molding having an undercut part by which the molded powder molding can be rapidly ejected from a die without using special jigs or devices and productivity can be improved. SOLUTION: A pair of disk-shaped cam dies 6, 7 provided with plural undercut molded parts 6a, 7a on a circumference are arranged between split faces of the die divided into upper and lower parts with rotability and a powder molding C can be ejected from the die by rotating the cam dies 6, 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method and a molding apparatus for a powder compact used for molding a powder compact in powder metallurgy or compression molding of a thermosetting resin. The present invention relates to a method and an apparatus for molding a powder compact having an undercut portion positioned in a direction perpendicular to the.

[0002]

2. Description of the Related Art Conventionally, for example, an apparatus as shown in FIG. 8 has been used for molding an ordinary powder compact having no undercut portion.

That is, the powder compact 10 formed by pressing the material powder in the die hole 101a of the die 101 by the lower punch 102 and the upper punch (not shown).
8 is extruded by the lower punch 102 onto the upper surface of the die 101 as shown in FIG. 8A, and then the jig 103a attached to the tip of the feeder box 103 as shown in FIG. 8B. Is pushed to the side of the chute 104 installed on the front of the device,
The powder compact 100 is conveyed to the next step via the chute 104. Then, the powder compact 100 becomes the chute 104.
At the same time, the lower punch 102 descends,
The material powder P is fed from the feeder box 103 to the die hole 10
Since it is supplied into the inside of 1a, continuous and efficient powder molding is possible.

On the other hand, when molding a powder compact having an undercut portion, for example, JP-A-6-395 is used.
As shown in Japanese Patent Laid-Open No. 96-96, a molding apparatus in which a die is vertically divided into two parts and a cam die having an undercut molding part corresponding to the shape of the undercut part is arranged between the divided surfaces of the die. Need to use. In this case, the feeder box that supplies the material powder moves on the upper surface of the upper die, and the discharge of the molded powder compact is
Since it is performed on the upper surface of the lower die, that is, between the upper and lower dies,
The feeder box cannot be used to discharge the molded product.

Therefore, an extruding device for discharging the molded product is arranged between the upper and lower dies, but there is little space between the upper and lower dies, and it is difficult to install the extruding device. In this case, the die thickness may be insufficient or unbalanced, which may adversely affect the roundness of the molded body. Therefore, it is necessary to dispose the extrusion device outside the upper and lower dies.

That is, FIGS. 9 to 11 show an outline of the procedure for molding a powder compact by such an apparatus. The molding apparatus used in this method is an upper die 105 and a lower die which are divided into upper and lower parts. Die 106 and these dies 10
5 and 106 are provided with cam dies 107 and 107 having an undercut molding portion 107a and an air cylinder 108 (see FIGS. 10 and 11) which is an extruding device.

In order to mold a powder compact having an undercut portion using the compacting device having such a structure, first, as shown in FIGS. 9 (a) and 9 (b), the lower die 10 is used.
The lower punch 109 inserted in the die hole 106a of No. 6 is lowered to a predetermined position, and the cam dies 107, 10
7 is a die hole 105a of the upper die 105 and the lower die 106
And the die hole 10 in a state of being projected into 106a.
Material powder P is supplied from the feeder box 103 into 5a and 106a. And feeder box 1
03 is moved, and then the die hole 105a of the upper die 105
A predetermined pressure is applied to the material powder P in the die holes 105a and 106a by the upper punch (not shown) inserted therein and the punch 109, and the molding of the material powder P proceeds.

When the compression molding of the molded body 100 is completed, as shown in FIGS. 10 (a) and 10 (b), the cam die 10 is pressed.
7,107 retreat, the upper die 105 rises,
The lower punch 109 rises to the upper surface of the lower die 106. At the same time, the air cylinder 108, which is a pushing device, starts the pushing operation, and the jig 108a provided at the tip of the cylinder rod comes into contact with the molded body 100.

Then, as the air cylinder 108 is further pushed out, the molded body 100 is pushed out to the chute 104 side and conveyed from the chute 104 to the next step, as shown in FIGS. It is like this.

[0010]

However, in the above-mentioned conventional molding apparatus, since the air cylinder 108, which is the pushing device, is disposed outside the upper and lower dies 105 and 106, the stroke of the air cylinder 108 is reduced. There is a problem in that it is necessary to increase the length, and it takes time to extrude the molded body 100, the molding cycle becomes long, and the productivity cannot be improved.

When changing the shape of the undercut portion when molding the powder compact having the undercut portion as described above, the cam dies 107, 107 must be replaced, and the replacement work and the setup work must be performed. for,
There is also a problem that productivity is often deteriorated as a result of molding being interrupted, and solving these problems has been a problem in a conventional molding method or molding apparatus for a powder compact having an undercut portion. .

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in the conventional molding method or apparatus for a powder compact having an undercut portion, and the first object of the present invention is to provide a special treatment. To provide a molding method and a device for a powder molded body, which can quickly discharge a molded powder molded body from a die without using tools and devices, and can improve productivity by shortening a molding cycle. is there.

A second object of the present invention is to change the shape of the undercut portion without replacing the cam die when forming a powder compact having an undercut portion, which deteriorates the productivity. Another object of the present invention is to provide a molding device that can easily cope with changes in the shape of the undercut portion.

[0014]

A method for molding a powder compact having an undercut portion according to claim 1 of the present invention comprises:
A die with a die hole filled with the material powder is divided into parts corresponding to the undercut portion of the powder compact, and a disc-like shape is formed on the circumference of the die corresponding to the shape of the undercut portion. A pair of cam dies provided with parts are rotatably disposed between the divided surfaces of the die, and the material powder filled in the die holes is placed in a state in which the undercut forming part of the cam die is positioned in the die holes. The present invention is characterized in that it is configured such that pressure is applied by punches press-fitted from both end openings of the die hole, and the formed powder compact is discharged by the rotational operation of the pair of cam dies, and such an undercut portion is provided. The constitution of the method for molding a powder compact is used as a means for solving the above-mentioned conventional problems.

A molding apparatus for a powder compact having an undercut portion according to a second aspect of the present invention is provided with a die hole filled with a material powder, and is divided at a portion corresponding to the undercut portion of the powder compact. A pair of cam dies having a disc shape and having an undercut molding portion corresponding to the shape of the undercut portion on the circumference is rotatably arranged between the divided surfaces of the formed die. A feature of the present invention is that the structure of the molding apparatus for a powder compact having such an undercut portion is used as a means for solving the above-mentioned conventional problems.

A third aspect of the present invention is an apparatus for shaping a powder compact having an undercut portion according to the present invention.
5. The molding apparatus according to claim 4, wherein the cam die has a plurality of undercut molding portions on the circumference, and the plurality of undercut molding portions have the same shape and the same size. In the apparatus, the cam die has a plurality of undercut molding portions on a circumference thereof, and the plurality of undercut molding portions have different shapes or sizes, respectively. In the molding apparatus, the punch to be press-fitted into the die hole of the die comprises a hollow sleeve punch inserted into the die hole, and a core punch slidably inserted into the hollow portion of the sleeve punch. Such a configuration in a molding apparatus for a powder compact having an undercut portion is used as a means for solving the above-mentioned conventional problems. It is characterized in.

[0017]

In the method for molding a powder compact having an undercut portion according to the first aspect of the present invention, the cam die is a disk-shaped rotary type, and the undercut molding portion of the cam die is located in the die hole. After molding the powder compact in this state, by rotating the cam die, the powder compact is discharged from the die.
The molded powder compact is promptly discharged from the die without using a discharging jig or device, so that the productivity is improved.

According to a second aspect of the present invention, there is provided an apparatus for molding a powder compact having an undercut portion, wherein a circumference of a die is divided by a portion corresponding to the undercut portion of the powder compact. 1 with an undercut molding part on top
Since the pair of disc-shaped cam dies are rotatably arranged, the structure is suitable for carrying out the method for molding a powder compact having an undercut portion according to the present invention.

According to a third aspect of the present invention, there is provided a molding apparatus for a powder compact having an undercut portion, wherein a plurality of undercut molding portions having disk-shaped cam dies having the same shape and size. Since it is provided on the circumference, the powder compact is discharged by the rotation of the cam die, and at the same time the cam die goes into a standby state for the next molding, which shortens the molding cycle and improves the productivity. It will be. On the contrary,
In the molding apparatus according to claim 4, since the disk-shaped cam die is provided with a plurality of undercut molding portions having different shapes or sizes on the circumference, when changing the shape of the undercut portion, the cam die is replaced or the cam die is changed. This eliminates the need for setup work associated with the above, and improves the production efficiency of powder compacts. In order to continuously mold the powder compact having the same shape using the molding apparatus, the powder compact may be discharged and then the cam die may be rotated in the reverse direction or may be rotated once in the discharge direction of the compact.

Similarly, in a molding apparatus according to a fifth aspect of the present invention, the punch press-fitted into the die hole of the die comprises a hollow sleeve punch and a core punch fitted in the hollow portion of the sleeve punch. Therefore, at the time of molding, the compression ratio between the upper and lower outer peripheral portions of the undercut portion and the central portion can be freely adjusted, and variations in density due to the parts of the powder compact can be eliminated.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

2 to 6 are process diagrams showing the structure of a molding apparatus for a powder compact having an undercut portion according to one embodiment of the present invention and sequentially explaining the molding procedure by the apparatus.

The forming apparatus 1 shown in the figure has a cylindrical upper die 2 and lower die 3 which are divided into upper and lower parts, and a shaft 4 which is disposed between the upper and lower dies 2 and 3 and which penetrates the upper and lower dies 2 and 3. And 5 and a pair of cam dies 6 and 7 which are synchronously rotated by a controller (not shown) and an upper die 2
Upper punch 8 and lower die 3 inserted into the die hole 2a of
Of the lower punch 9 to be inserted into the die hole 3a, the upper punch 8 and the lower punch 9 are a hollow cylinder-shaped first upper punch 8a and a first lower punch 9a (sleeve punch), respectively. A second upper punch 8b and a second lower punch 9 fitted in the hollow portions of the upper and lower first punches 8a, 9a.
It consists of b (core punch).

The upper and lower dies 2, 3, the first upper punch 8a, the second upper punch 8b, the first lower punch 9a and the second lower punch 9b are respectively attached to the cam dies 6 and 7 by a drive cylinder (not shown). It is designed to operate vertically relative to each other.

The cam dies 6 and 7 are disc-shaped,
In this embodiment, semicircular recesses 6a and 7a having a radius corresponding to the radius of the undercut portion of the target powder compact are provided at four locations on the circumference, respectively. It constitutes an undercut forming part. The cam dies 6 and 7 are fixed to the shafts 4 and 5 as described above, and are synchronously rotated by a control device and a rotation driving mechanism (not shown), and the cam dies 7 on the right side in the drawing contact the cam dies 6 as they rotate. While keeping the contact state, the shaft 5 and the shaft 5 move horizontally.

In order to mold a powder compact having an undercut portion using the compacting device 1 having the above structure, first, as shown in FIGS. 2 (a) and 2 (b), undercuts of the cam dies 6 and 7 are performed. The cam dies 6 and 7 are rotated so that the cut forming portions 6a and 7a are located in the die holes 2a and 3a of the upper and lower dies 2 and 3, and in this state, the material powder P
The feeding feeder 10 is placed on the upper surface of the upper die 2, and the material powder P is filled in the molding space formed by the die holes 2a and 3a and the undercut forming portions 6a and 7a of the cam dies 6 and 7. At this time, there is a portion where the material powder P does not enter immediately below the undercut forming portions 6a and 7a. Therefore, in consideration of this, the lower punches 9a and 9b are lowered in advance to prevent the filling amount from becoming insufficient.

Next, the feeder 10 is moved to move the upper die 2
The excess material powder P remaining on the upper die 8 is recovered, and as shown in FIGS. 3 (a) and 3 (b), the upper punches 9a and 9b are inserted into the die holes 2a of the upper die 2 to form the upper and lower punches 8a. , 8b, 9a, 9b are moved to transfer the filled material powder P, and the compression ratios of the upper and lower outer peripheral portions of the powder compact and the central portion are adjusted to be the same. Make the density uniform.

Then, the upper and lower punches 8a, 8b, 9a, 9
By applying a predetermined molding pressure to b, as shown in FIG.
And as shown in (b), the molding of the powder compact C is completed.

Then, as shown in FIGS. 5 (a) and 5 (b), the upper die 2 is raised and the lower die 3 is lowered while the powder compact C is held by the cam dies 6 and 7. As a result, the powder compact C is extracted from the die holes 2a and 3a of the upper and lower dies 2 and 3.

When it is detected that the powder compact C has been extracted from the upper and lower dies 2 and 3 by a control device (not shown) via a limit switch or a rotary encoder, etc., FIGS. 6 (a) and 6 (b). As shown in FIG. 2, the shaft 4 and the cam die 6 start rotating in the direction of the arrow in the figure via a rotation drive mechanism (not shown), and the shaft 5 maintains the contact state between the cam die 6 and the cam die 7 while Rotate while moving horizontally toward the center right. As a result, as shown in FIGS. 1A and 1B, the molded powder compact C having the undercut portion U is separated from the cam dies 6 and 7, and is provided on the front surface of the molding apparatus 1. It is discharged to the side of a chute (not shown) and is conveyed to the next step through the chute. At this time, the powder compact C
May be sandwiched by the undercut forming portion 6a or 7a of the cam die by the spring back and may be difficult to separate from the cam die. Therefore, it is desirable to provide a guide near the entrance of the chute. The powder compact C is easily separated from the cam die and discharged to the chute by coming into contact with the guide while rotating with the cam die.

By rotating the cam dies 6 and 7 by 90 ° in this embodiment, respectively, the powder compact C is discharged from the compacting device 1 as described above, and at the same time, the following undercut forming portions 6a and 6a are formed. Since 7a abuts each other and becomes the molding position for the next cycle, the cycle of molding can be increased and the productivity of molding can be improved. Further, in the molding apparatus 1, since the cam dies 6 and 7 are rotationally operated, the material powder P entering the butt portion is more easily discharged as compared with the conventional molding apparatus using the slide butt type cam dies, At the same time, the effect of reducing the galling and seizure of the die and prolonging the service life of the device is achieved.

FIGS. 7A and 7B show another example of the shape of the cam die, and the cam die 1 shown in the drawings.
6 and 17 are disc-shaped like the cam dies 6 and 7, and are semi-circular undercut forming portions 16a, 16b, which have different radii of curvature from each other at four locations on the circumference.
16c, 16d and 17a, 17b, 17c, 17d
And a cam die 1 having such a shape.
By using 6 and 17, the cam die is
6, 17 at a predetermined angle (90 °, 180 in this embodiment)
.Degree. And 270.degree.), The diameter of the undercut portion U of the powder compact C can be easily changed. In this case, after the powder compact C is discharged, the cam dies 16 and 17 are rotated in the reverse direction or the control is changed to rotate once in the discharge direction of the compact so that the powder compacts having the same shape are continuously formed. Can handle molding.

In the above embodiment, the example in which the undercut forming portions are provided at four positions on the circumference of the cam die is shown, but the diameter of the cam die and the number of the undercut forming portions are intended. It goes without saying that the amount can be appropriately increased or decreased according to the shape and size of the undercut portion.

[0034]

As described above, according to the first aspect of the present invention.
In the method for molding a powder compact having an undercut portion according to, the cam die is of a rotary type, and the powder compact molded by rotating the cam die is discharged from the die. The powder compact after molding can be quickly discharged from the die without the use of jigs or equipment, which makes it possible to improve productivity and the conventional molding equipment that uses a sliding butting type cam die. Was a problem in
An extremely excellent effect that it is possible to prevent the occurrence of image sticking or galling due to the invasion of the material powder into the abutting portion is brought about.

According to a second aspect of the present invention, there is provided an apparatus for molding a powder compact having an undercut portion, which has the above-described structure, that is, between the divided surfaces of a die divided into parts corresponding to the undercut portion of the powder compact. In addition, since a pair of disc-shaped cam dies having an undercut molding portion on the circumference is rotatably arranged, the method for molding a powder molding product having an undercut portion according to the present invention. It has a structure suitable for, and has an extremely excellent effect that the molding method according to the present invention can be smoothly carried out.

In a molding apparatus according to claim 3 as an embodiment of a molding apparatus for a powder compact having an undercut portion according to the present invention, a plurality of undercut molding portions having the same shape and the same size as the cam die are circumferentially surrounded. Since it is equipped with the above, the cam die will be set to the next molding standby state at the same time by the rotation for discharging the powder compact, which shortens the molding cycle and improves the productivity. In the forming apparatus according to item 4, since the cam die has a plurality of undercut forming portions each having a different shape or size on the circumference, only by rotating the cam die by a predetermined angle, the cam die can be exchanged and the setup involved can be performed. The undercut shape of the powder compact can be easily changed without any work, and the changeover time is shortened. It is possible to improve the productivity of Suenari form.

In the molding apparatus according to the fifth aspect of the present invention, the punch press-fitted into the die hole is composed of a sleeve punch and a core punch. It is possible to freely adjust the compression ratio, and to eliminate the variation in the compression ratio depending on the site, and to make the density of the powder compact uniform.

[Brief description of the drawings]

1A and 1B are perspective explanatory views conceptually showing the discharge principle of a powder compact in a molding method and apparatus for a powder compact having an undercut portion according to the present invention.

FIG. 2 (a) is a process diagram showing a forming procedure of a powder compact having an undercut portion according to the present invention, which is a vertical cross-sectional view showing a state in which a material powder is supplied into a die hole of a compacting device. is there. (B) It is a horizontal sectional view showing the state of the cam die in Drawing 2 (a).

3A is a vertical cross-sectional view showing the next step of FIG. 2A, showing the starting state of pressurization after the transfer of the filled material powder is completed. FIG. (B) It is a horizontal sectional view showing the state of the cam die in Drawing 3 (a).

FIG. 4 (a) is a vertical cross-sectional view showing the next step of FIG. 3 (a) and showing the end state of the molding of the powder compact. (B) It is a horizontal sectional view showing the state of the cam die in Drawing 4 (a).

5A is a vertical cross-sectional view showing the next step of FIG. 4A, showing a state in which the upper die and the lower die are respectively raised and lowered. FIG. (B) It is a horizontal sectional view showing the state of the cam die in Drawing 5 (a).

FIG. 6 (a) is a vertical cross-sectional view showing the next step of FIG. 5 (a) and showing the discharge state of the molded powder compact. FIG. 6B is a horizontal sectional view showing the positional relationship of the cam dies in FIG.

7A and 7B are horizontal cross-sectional views showing another example of the shape of the cam die.

8 (a) and 8 (b) are schematic explanatory views showing a conventional molding procedure of a powder compact having no undercut portion.

FIG. 9 (a) is a process diagram showing a conventional molding procedure for a powder compact having an undercut portion, and is a vertical cross-sectional view showing a supply state of material powder. (B) It is a horizontal sectional view in the cam die position of FIG. 9 (a).

FIG. 10 (a) is a vertical cross-sectional view showing a state where the molding is completed and the powder compact is discharged. (B) It is a horizontal sectional view in the cam die position of FIG. 10 (a).

FIG. 11 (a) is a vertical sectional view showing a discharge state of a powder compact. (B) It is a horizontal sectional view in the cam die position of FIG. 11 (a).

[Explanation of symbols]

1 Molding Equipment 2 Upper Die 2a Die Hole 3 Lower Die 3a Die Hole 6,7 Cam Dies 6a, 7a Undercut Forming Part 8 Upper Punch 8a First Upper Punch (Sleeve Punch) 8b Second Upper Punch (Core Punch) 9 Lower Punch 9a First lower punch (sleeve punch) 9b Second lower punch (core punch) 16,17 Cam dies 16a, 16b, 16c, 16d, 17a, 17b, 1
7c, 17d Undercut forming part P Material powder C Powder forming body U Undercut part

Claims (5)

[Claims] 1. A die having a die hole filled with a material powder is divided at a portion corresponding to an undercut portion of a powder compact, and has a disc shape to form an undercut portion on a circumference. A pair of cam dies having corresponding undercut molding portions are rotatably disposed between the divided surfaces of the die, and the undercut molding portions of the cam dies are positioned in the die holes, Powder molding having an undercut portion, characterized in that the filled material powder is pressed by punches press-fitted from both end openings of the die hole, and the molded powder compact is discharged by the rotational operation of the pair of cam dies. Body shaping method. 2. A disk-shaped undercut is provided between the divided surfaces of the die, which is provided with a die hole filled with the material powder and is divided at a portion corresponding to the undercut portion of the powder compact. A pair of cam dies provided with an undercut molding part corresponding to the shape of the parts are rotatably arranged, and a molding apparatus for a powder compact having an undercut part. 3. The cam die according to claim 2, wherein the cam die has a plurality of undercut molding portions on its circumference, and the plurality of undercut molding portions have the same shape and the same size. A molding device for a powder compact having an undercut portion. 4. The cam die according to claim 2, wherein the cam die has a plurality of undercut molding portions on a circumference thereof, and the plurality of undercut molding portions have different shapes or sizes. A molding device for a powder compact having an undercut portion. 5. The punch press-fit into the die hole of the die comprises a hollow sleeve punch inserted into the die hole, and a core punch slidably inserted in the hollow portion of the sleeve punch. A molding apparatus for a powder compact having an undercut portion according to any one of claims 2 to 4.