JP3173157B2 - Powder molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder compacting apparatus for compressing powder to obtain a green compact having a predetermined shape.

[0002]

2. Description of the Related Art In powder molding, in order to obtain a green compact having a uniform density, the powder is usually filled into a mold by top-cutting so as to have a similar shape to the green compact. However, in the case where the green compact W has a web Wb at an intermediate portion in the cylindrical portion Wa as shown in FIG. It would not be possible to fill the powder into shape.
Therefore, when such a green compact W is obtained, the portion of the powder corresponding to the web Wb is transferred in a mold prior to compression, and generally, a floating lower punch for forming the web Wb is used. Is forcibly depressed by a rod supported on a press upper ram via a cylinder device to transfer powder, and after transferring powder, the pressing force of the cylinder device is released to perform compression molding ( For example, Tokiko Sho 53
-11701). However, in such a mechanism, since the rod and the cylinder device are installed outside the mold, there is a problem that the entire device expands in the lateral direction and the installation space increases.

To solve this problem, Japanese Patent Publication No. 63-35360 discloses a method in which a floating upper punch is provided on an upper press ram and a switching circuit for switching between a high-pressure fluid and a low-pressure fluid is connected to a cylinder device supporting the floating lower punch. By supplying a low-pressure fluid to the cylinder device supporting the floating lower punch, powder transfer is performed using a pressure difference with the cylinder device supporting the floating upper punch,
Thereafter, an apparatus is disclosed in which a cylinder device supporting the floating punch is switched to a high pressure to generate a powder holding force. According to such a device, since the cylinder device that supports each floating punch is arranged in the mold, the spread in the horizontal direction is suppressed, and the above-described increase in the installation space can be prevented.

[0004]

However, according to the device disclosed in Japanese Patent Publication No. 35360/1988, in order to generate a desired holding force, a considerably high pressure is required as a cylinder device for supporting the floating lower punch. There is a problem that a large-sized device is required, and the device is inevitably increased in size.
Further, since a low-voltage and high-voltage switching circuit is required, not only the structure becomes complicated, but also maintenance becomes troublesome, and there is a problem that an increase in cost burden cannot be avoided.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has as its object to reduce the size and simplification of a powder transfer mechanism, thereby improving maintainability and reducing equipment costs. Another object of the present invention is to provide a powder molding apparatus which greatly contributes to the above.

[0006]

According to the present invention, in order to achieve the above object, a die is movably disposed in a die holder which moves up and down in association with a lower ram, and the die is moved upward by an urging means. The fixed lower punch and the floating lower punch are fitted and arranged on the punch plate whose position is fixed, and the fixed lower punch is fixedly supported by the punch plate, and the floating lower punch is fixed to the punch plate. It is supported by the piston rod of the cylinder device provided, and one end of a connecting rod interlocked with the lower press ram is introduced into the bore of the cylinder device, and the upper press ram is provided with the fixed lower punch and the floating lower punch respectively. A fixed upper punch and a floating upper punch are provided to face each other, the powder in the die is partially transferred by causing the floating lower punch to follow the descent of the floating upper punch, and The piston of the cylinder device in the vicinity of end of the transport end, characterized by being configured so as to abut on the connecting rod.

[0007]

In the powder compacting apparatus constructed as described above, the powder transfer becomes smooth by setting the cylinder device to a low pressure, and after the powder is transferred, the piston in the cylinder device abuts on the connecting rod, and the powder is transferred under the press. Since a large pressing force of the ram is applied to the powder, a desired holding force can be secured.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a powder molding apparatus according to the present invention. In the figure, 1 is a lower pressable ram, 2 is a base plate fixed to the lower press ram 1 using a clamp member 3, 4 is a punch plate fixed in position, 5 is a die holder, and die holder 5 is a base plate 2 And is supported by the upper end of a guide bar 6 extending upward through the punch plate 4 and moves up and down integrally with the press lower ram 1.

The die holder 5 has an annular groove 5a on its inner periphery, and an inner die holder 7 is slidably fitted in the annular groove 5a. A die 10 is mounted and fixed on the inner die holder 7 using a die plate 8 and a die retainer 9. The die 10 is normally urged upward by an urging means (not shown) interposed between the die plate 8 and the punch plate 4.
Is usually the annular groove 5a of the die holder 5 as shown in FIG.
Is positioned at an ascending end that abuts on the upper end wall of the main body. A spacer is provided on the lower surface of the inner die holder 7.
11 is held down, and a die stopper 12 is provided on the punch plate 4. The inner die holder 7 is configured such that the lower end thereof is regulated by bringing the spacer 11 into contact with the die stopper 12. The compact to be formed in the present embodiment is the same as that shown in FIG. 3 described above, but a small outer flange Wc is provided at the inner edge of the upper end of the compact, and The step 10 has a step 10a for forming the outer flange Wc.

A fixed lower punch 13 and a floating lower punch 14 are slidably fitted inside the die 10 so as to be mutually slidable. The fixed lower punch 13 is for forming a cylindrical portion Wa of the green compact W, and a spacer
Fixed through 15. On the other hand, the floating lower punch 14
This is for forming a web Wb of the green compact W, and is supported via a punch holder 18 on the upper end of a piston rod 17 extending from a cylinder device 16 provided in the punch plate 4. A piston 19 for supporting the lower end of the piston rod 17 is slidably provided in a bore 16a of the cylinder device 16. The lower end opening of the bore 16a of the cylinder device 16 is closed by a rod guide 20 fixed to the punch plate 4, and low pressure air is supplied to a portion between the rod guide 20 and the piston 19 in the bore 16a. It has become so. A cylindrical stopper 21 is disposed on the upper side in the bore 6a, and the piston 19 is normally urged upward by the air pressure, and is positioned at a rising end in contact with the stopper 21. . In this state, the upper end of the floating lower punch 14 protrudes more than the fixed lower punch 13 and is positioned at a position lower than the upper end of the die 10 by a predetermined distance, whereby the die 10, the fixed lower punch 13 and the floating lower punch 14 A powder filling space (cavity) C having a size of?

A connecting rod 22 is slidably fitted in the rod guide 20. The lower end of the connecting rod 22 is seated on a spacer 23 placed on the base plate 2 and follows the movement of the lower ram 1. Thus, a predetermined gap δ is formed between the upper end of the connecting rod 22 introduced into the bore 16a of the cylinder device 16 and the piston 19 positioned at the rising end. This gap δ corresponds to the transfer distance of the powder P, which will be described later. At the time of powder transfer in which the floating lower punch 14 descends, the piston 19 descends so as to fill the gap δ and hits the connecting rod 22 simultaneously with the end of the powder transfer. Touch Therefore, after the transfer of the powder is completed, the pressing force of the press-down ram 1 is transmitted to the piston 19, that is, the floating lower punch 14 via the connecting rod 22, and the floating lower punch 14 generates a predetermined holding force. The punch holder 18 comes into contact with a punch stopper 24 provided on the upper surface of the punch plate 4 so that its lower end is regulated. At this stage, the floating lower punch 14 is fixed in position, A large pressing force required for compression molding is generated.

On the other hand, a fixed upper punch 31 and a floating upper punch 32 are arranged on the press upper ram 30 so as to face the fixed lower punch 13 and the floating lower punch 14, respectively. Fixed upper punch
31 is fixed to the lower end of a cylinder 34 of an upper cylinder device 33 fixed to the press upper ram 30, while the floating upper punch 32 is directly connected to a piston 35 of the upper cylinder device 33. The piston 35 is always positioned at the lower end by the air pressure introduced into the cylinder 34, so that the floating upper punch 32 precedes the fixed upper punch 31 by the moving stroke a of the piston 35. In addition, this upper cylinder device
The generated pressure of 33 is set to be considerably higher than the generated pressure of the cylinder device 16 supporting the floating lower punch 14.

Hereinafter, the operation of the powder molding apparatus configured as described above will be described with reference to FIG.

At the time of compression molding, the upper ram 30 is first raised as shown in FIG.
The lower punch 14 is raised by the operation of, and the powder P is filled into the cavity C defined by the die 10, the fixed lower punch 13, and the lower punch 14 by top cutting. Next, the press upper ram 30 is lowered. Then, since the floating upper punch 32 largely precedes the fixed upper punch 31, the floating upper punch 32 enters the die 10. At this time, since the pressure generated by the cylinder device 16 supporting the floating lower punch 14 is considerably low, the portion of the powder corresponding to the web Wb of the green compact W is sandwiched between the floating punches 32 and 14. Moves the inside of the die 10 downward.

Finally, as shown in FIG.
The piston 19 in the cylinder device 16 fills a predetermined gap δ (FIG. 1) and abuts on the upper end of the connecting rod 22, and the pressing force of the press-down ram 1 is applied via the piston rod 17 and the punch holder 18 to the floating lower punch 14. Is transmitted to At this stage, the lower end of the fixed upper punch 31 reaches the step 10a of the die 10, and a predetermined gap b exists between the punch holder 18 and the punch stopper 24. Just leave a stroke margin.

Thereafter, when the press upper ram 30 is further lowered, the fixed upper punch is passed through the powder in the step 10a of the die 10.
The downward force of 31 is transmitted to the die 10, and the fixed upper punch 31 and the die 10 are integrally lowered as shown in FIG. 2B, and the powder of the portion corresponding to the cylindrical portion Wa of the green compact W is removed. It is gradually compressed. At this time, since the pressing force of the press lower ram 1 is applied to the floating lower punch 14, the floating upper punch 32 relatively rises, and finally the piston 35 of the upper cylinder device 33 reaches the stroke end, and The relative movement of the upper punch 32 is restricted,
At the same time, the die 10 descends within the die holder 5 by a predetermined distance c. When the relative movement of the floating upper punch 32 is restricted, the holding force of the lower press ram 1 is applied to a portion of the powder corresponding to the web Wb of the green compact W.

When the press upper ram 30 is further lowered, the lowering force is transmitted to the press lower ram 1 via the floating upper punch 32, the powder P, the floating lower punch 14, the piston rod 17, the connecting rod 22, etc. As shown in (c), the lower press ram 1 is pushed down by a gap b between the punch holder 18 and the punch stopper 24. During this time, the web W of the green compact W
Since the holding force of the ram 1 under the press is applied to the powder in the portion corresponding to b, the powder in this portion is pre-compressed.
Then, as shown in FIG. 2D, when the punch holder 18 abuts against the punch stopper 24 and the die spacer 11 abuts against the die stopper 12, a large compressive force is applied to the powder P,
The final molding in which the density is increased is performed, and a green compact W similar to that shown in FIG. 3 is obtained. After that,
The press lower ram 1 descends greatly and the die 10 becomes the die holder 5
, And the green compact W is discharged from the die 10, and thereafter, each member returns to the original position shown in FIG. 1, and a series of powder molding is completed.

According to the powder molding apparatus having the above-described structure, the cylinder device 16 is set at a low pressure,
In the first powder transfer stage, the powder P is only slightly compressed, so that the powder does not condense and hinder the subsequent molding. After the powder is transferred, the piston 19 in the cylinder device 16 comes into contact with the connecting rod 22, so that a large pressing force of the lower ram 1 is applied, and the powder in the portion corresponding to the web Wb is pre-compressed. The powder at the portion corresponding to the cylindrical portion Wa is not extruded to the inside, and cracks are not generated at the connection portion between the cylindrical portion Wa and the web Wb. In this embodiment,
In particular, since the lower end of the connecting rod 22 is brought into contact with the base plate 2 via the spacer 23, the transition timing to the pre-compression molding can be adjusted by selecting the spacer 23 having an appropriate thickness. More stable compression moldability can be established according to the shape of the powder.

[0020]

As described above in detail, according to the powder molding apparatus according to the present invention, the holding force of the powder is generated by utilizing the rising force of the ram under the press. As the cylinder device for supporting the lower punch, only the powder transfer needs to be considered, so a small device is sufficient, and the structure of the device can be simplified and reduced in size.
The maintenance cost can be improved as well as the maintenance cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a compression molding apparatus according to the present invention.

FIG. 2 is a sectional view showing a use state of the present compression molding apparatus in order.

FIG. 3 is a sectional view showing an example of a shape of a green compact obtained by the present compression molding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Press lower ram 5 Die holder 10 Die 13 Fixed lower punch 14 Floating lower punch 16 Cylinder device 16a bore 17 Piston rod 18 Punch holder 19 Piston 22 Connecting rod 30 Press upper ram 31 Fixed upper punch 32 Floating upper punch P Powder W Compaction

Claims (1)

(57) [Claims] A die is movably arranged in a die holder which moves up and down in association with a press lower ram, and the die is urged upward by an urging means to form a fixed lower punch on a fixed position punch plate. The floating lower punch is fitted and arranged, and the fixed lower punch is fixedly supported on the punch plate, and the floating lower punch is supported on a piston rod of a cylinder device provided on the punch plate. One end of a connecting rod interlocked with the lower press ram is introduced into the bore, and the upper press ram is provided with a fixed upper punch and a floating upper punch facing the fixed lower punch and the floating lower punch, respectively. The powder in the die is partially transferred by making the floating lower punch follow the lowering of the upper punch, and the piston of the cylinder device is moved near the transfer end of the powder. A powder molding apparatus characterized in that it is brought into contact with a connecting rod.