JPH0320074Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a powder forming machine for forming powder metallurgy materials, such as fuel pellets in a nuclear reactor.

[Technical background of the invention and its problems]

Generally, when molding a powder metallurgical material such as the fuel pellets mentioned above, powder supplied into a die is compressed and molded using both upper and lower punches.

FIG. 2 is a longitudinal sectional view of a powder molding machine, particularly a rotary type powder molding machine, for performing compression molding as described above. A shaft 3 is erected. A vertical shaft oil receiver 4 is fixedly installed on the upper surface of the frame 1 concentrically with the vertical shaft 3, and further above the vertical shaft oil receiver 4, a rotary disk 5 is mounted relative to the vertical shaft 3. It is rotatably mounted.

The rotary disk 5 has an upper flange portion 5a, a center flange portion 5b, and a lower flange portion 5c integrally formed on its outer periphery, and the center flange portion 5b has a shape as shown in FIG. A large number of dies 6 are provided in the circumferential direction. Further, an upper punch holder 7 that holds an upper punch 7a on the same axis as each of the dies 6 is vertically movably disposed on the upper flange-shaped portion 5a, and the lower flange-shaped portion 5c is also provided with an upper punch holder 7 that holds an upper punch 7a on the same axis as each of the dies 6. A lower punch holder 8 holding a lower punch 8a is disposed on the same axis as the lower punch holder 8 and is movable up and down. The driving gears 10 are meshed with each other.

On the other hand, the lower punch holder 8 has a rotary disk 5.
A guide roller 11 is attached to the outside of the portion protruding downward from the guide roller 11.
It is engaged with a guide groove 12 disposed on the frame 1 over a predetermined range in the circumferential direction. Further, guide rollers 13 are installed on both sides of the portion of the upper punch holder 7 that protrudes upward from the rotary disk 5, and guide rollers 13 are provided in guide grooves disposed over a predetermined range in the circumferential direction at a position above the rotary disk 5. 14.

Also, insert the upper punch 7a and the lower punch 8a into the die 6 from above and below, and
In the pressurizing process section for compression molding the powdered raw material supplied to the inside, pressurizing rollers 15 and 1 are in contact with the top end of the upper punch holder 7 and the lower end of the lower punch holder 8, respectively, and apply pressing force to both punches.
6 are arranged respectively. Note that the reference numeral 17 in FIG. 2 is a powder feeder.

Thus, when compressing powder, the rotary disk 5 is rotated via the drive gear 10, and at the same time, the powder is fed from the powder feeder 17 into the die 6 which has come to a predetermined position. Therefore, in accordance with the rotation of the rotary disk 5, the lower punch 8a is moved upward via the guide groove 12 and the guide roller 11 to a predetermined filling depth, and after removing the excess powder, the upper punch 8a 7a is gradually lowered, and the powder in the die 6 is held between the upper and lower punches 7a and 8a. When the upper and lower punches 7a and 8a, which are holding the powder in the die 6 in this manner, enter between the pressure rollers 15 and 16, the upper and lower punches 7a and 8a are moved by the pressure rollers 15 and 16.
a are pressed in a direction toward each other, and compression molding of the powder is performed.

When the pressurizing process is completed in this manner, the upper and lower punches 7a and 8a move upward with the molded product being held between the upper and lower punches 7a and 8a, and the lower punch 8a
When the upper surface becomes flush with the upper surface (die table) of the die 6, the upper punch 7a is moved further upward, and then the molded product is delivered. Thereafter, compression molding of the powder is sequentially performed within each die 6 in the same manner.

By the way, in such a powder molding machine,
When taking out the molded body from the die after compression molding, for example, if the upper punch 7a is suddenly raised, the pressure applied to the molded body is suddenly removed, which may cause cracks in the molded body.

Therefore, when taking out the molded product from the die, a hold-down pressure, a hold-up pressure, or a hold-down pressure and a hold-up pressure are applied to the molded product to prevent cracks from occurring in the molded product. There is.

That is, in the pressing stroke area shown in FIG.
As shown in the figure, a cam body 20 is disposed that contacts the guide roller 13 provided at the upper part of the upper punch holder 7 from above, and a piston 22 of a pressure cylinder device 21 is disposed at the lower part of one side of the cam body 20. are connected.

Then, the compression molding of the powder is completed, and the die 6 and the upper punch holder 7 that performed the compression molding
When the tool moves to the extrusion stroke area, the guide roller 13 provided on the upper punch holder 7 comes into contact with the cam surface 20a of the cam body 20, and the cam body 20, which is urged downward with a predetermined pressure by the pressure cylinder device 21, Therefore, the upper punch holder 7 and the upper punch 7a
is pressed downward, and hold-down pressure is applied to the molded body via the upper punch 7a.

However, in such a device, when the hold-down pressure is applied, a reaction force against the hold-down pressure is applied to the cam surface 20a of the cam body 20, causing the cam body 20 to rotate counterclockwise. The force to do this is added. Therefore, the force is supported between the piston 22 connected to the cam body 20 and the cylinder 23, especially in the parts indicated by A and B, and as the number of cylinder operations increases, the wear in these parts increases. , the pressure on the guide roller 13 no longer acts as planned,
This poses problems such as causing cracks in the molded product.

[Purpose of invention]

In view of these points, the present invention reliably prevents the cam body that applies hold pressure from tilting due to uneven wear and prevents the planned pressure from being applied to the guide roller, and reduces the hold pressure to the molded product. It is an object of the present invention to provide a powder compacting machine which can always maintain the powder compaction and reliably prevent the occurrence of cracks in the compact.

[Summary of the idea]

The present invention is a powder molding machine in which the powder supplied into the die is compression-molded by upper and lower punches, and the compact is extruded from the die while being held between the upper and lower punches. A cam body that engages with a guide roller provided on the punch holder and applies the punch hold pressure is provided on the piston rod of the pressure cylinder disposed on one side, and the cam body is provided with a cam body that applies the punch hold pressure. The present invention is characterized in that a reaction force support member is provided which is pressed against the fixed wall surface by reaction force.

[Example of idea]

FIG. 1 is a diagram showing an embodiment of the present invention, in which a cam body 2 is in contact with a guide roller 13 provided at the top of the upper punch holder 7 from above in the extrusion stroke area.
A piston 22 of a pressure cylinder device 21 is connected to the lower portion of one side of the cam body 20.

By the way, the cam body 20 is equipped with a roller 24 that comes into contact with the outer surface of the cylinder of the pressure cylinder device 21 on the side opposite to the upper punch holder 7.

Then, the compression molding of the powder is completed, and the die 6 and the upper punch holder 7 that performed the compression molding
When the tool moves to the extrusion stroke area, the guide roller 13 provided on the upper punch holder 7 comes into contact with the cam surface 20a of the cam body 20, and the cam body 20, which is urged downward with a predetermined pressure by the pressure cylinder device 21, Therefore, the upper punch holder 7 and the upper punch 7a
is pressed downward, and hold-down pressure is applied to the molded body via the upper punch 7a.

On the other hand, at this time, when the cam body 20 tries to tilt counterclockwise in the figure due to the reaction force against the hold-down pressure, the contact surface between the piston 22 and the cylinder inner wall and the piston rod 25 of the piston 22 come into contact with each other. Friction occurs between the two surfaces. However, since the roller 24 attached to the cam body 20 contacts the outer surface of the cylinder of the pressure cylinder device 20 and supports it on three surfaces, the tilting of the cam body 20 is prevented, and the guide roller 13 is always A pressing force is applied in a direction parallel to the axis of the upper punch holder 7, and the pressing force is always maintained at a set value.

[Effect of idea]

As explained above, in the present invention, a cam body engages with a guide roller provided on the punch holder and applies the punch hold pressure to the piston rod of a pressure cylinder provided on one side of the punch or punch holder. In addition, the cam body is provided with a reaction support member that is pressed against the fixed wall surface by the reaction force against the hold pressure, thereby preventing the cam body from tilting due to the reaction force against the hold pressure. Therefore, a pressing force in the axial direction of the punch holder is constantly applied to the guide roller, and the pressing force is prevented from gradually changing from the set value. Therefore, a predetermined holding pressure is always applied to the molded product, and the occurrence of cracks in the molded product is reliably prevented.

[Brief explanation of the drawing]

Fig. 1 is a partial view showing an embodiment of the powder compacting machine of the present invention, Fig. 2 is a vertical sectional view showing the schematic configuration of the powder compacting machine, Fig. 3 is a plan view of the die plate section,
The figure is an explanatory diagram of a conventional hold-down pressure biasing device section. 7...Top punch holder, 7a...Top punch,
13... Guide roller, 20... Cam body, 21...
Pressure cylinder device, 22... Piston, 24...
Roller, 25...piston rod.

Claims (1)

[Scope of utility model registration request] In a powder molding machine that compresses and molds the powder supplied into the die using upper and lower punches, and extrudes the compact from the die while holding the compact between the upper and lower punches, the powder is placed on one side of the punch or punch holder. A cam body is provided on the piston rod of the pressure cylinder provided therein, which engages with a guide roller provided on the punch holder and applies a hold pressure to the punch, and a cam body is provided with a cam body that applies a hold pressure to the punch by a reaction force against the hold pressure. A powder molding machine characterized by being provided with a reaction force support member that is pressed against a fixed wall surface.