JP4419117B2 - Lubricant supply method for pellet molding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for supplying a lubricant to a die before pellet molding.
[0002]
[Prior art]
Conventionally, pellets such as nuclear fuel pellets and cemented carbide chips have been formed by stopping the die holder so that the upper end of the lower punch is positioned below the die of the die holder, and then scraping the raw material powder into the die of the die holder. After the die holder is lowered and stopped so that the upper end of the lower punch comes close to the center of the die, the upper punch is inserted into the die from the upper side and lowered to compress the powder in the die and mold it into pellets. While raising the upper punch inside, the die holder was further lowered so that the upper end of the lower punch was flush with the upper end of the die of the die holder, and the molded pellets were pushed up from inside the die.
[0003]
However, due to the expansion force of the pellet molded body on the wall in the die, an extra force is applied to push down the die holder, and the pellet is not pushed up more smoothly than in the die and is broken in the die to form the desired pellet. I couldn't.
[0004]
For this purpose, a lubricant is mixed with this raw material powder, the mixture is scraped into the die of the die holder, the pellet is molded as described above, the upper punch is raised from within the die, and then the die holder Has been developed to form pellets from the mixture.
[0005]
Since the lubricant in the mixture comes into contact with the wall in the die due to the pellets from the mixture, an excessive force to push down the die holder is not applied, and the pellets in the die can be smoothly raised.
[0006]
[Problems to be solved by the invention]
However, the pellets of this mixture require equipment for the mixing process of the lubricant to be mixed with the powder body, which requires a significant investment in equipment costs and product costs. In addition, a large amount of lubricant is required for the mixture, but it is an impurity for the molded pellets, so it is difficult to reduce the amount of lubricant, and the lubricant in the pellets is removed by volatilization. In particular, it was necessary to provide a process (pre-sintering process (degreasing process)). In addition, there is a problem that hardness and density cannot be improved with pellets made of a mixture.
[0007]
Therefore, the present invention solves the problems of such conventional pellet molding, can reduce the equipment costs such as the mixing step and the pre-sintering step, and has high purity, while you can mold hardness and density improved pellets, the lubricant used can efficiently coating, can be achieved a significant reduction of the lubricant used.
Furthermore, since the mist-like lubricant is attached to the inner wall of the die by the suction force generated when the die is raised, it can be applied more uniformly.
Also, since the mist-like lubricant is applied by swirling flow or upward flow along the inner wall of the die, the pellet molding method and molding aiming to improve the adhesion by increasing the adhesion to the inner wall of the die. It is in providing the supply method of the lubricant used for.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the structure of the method of supplying the lubricant used in the pellet molding of the present invention includes a sprayer 1 for making the lubricant into a mist and a valve for supplying the mist lubricant b from the sprayer 1. 2 and the supply pipe 4 for sucking outside air through the outside air suction valve 24 and a valve for discharging the excess mist lubricant b supplied to the die 14. And a suction pipe 9 for sucking the mist lubricant b in the supply pipe 4 and the discharge pipe 8, and when the mist lubricant b reaches the lubricant cup 10. Then, the supply valve 2 and the discharge valve 7 are closed, and then the outside air suction valve 24 is opened, and the mist lubricant b is lubricated by the outside air suction force generated when the die holder 15 is raised. Pull it into the die 14 from the agent cup 10, It is a natural adhesion or forcibly applied constituting the inner wall of the chair 14.
[0009]
Further, the structure of the method of supplying the lubricant used for pellet molding according to the present invention is that the sprayer 1 that makes the lubricant into a mist and the mist lubricant b from the sprayer 1 are guided to the injection hole 23 installed in the die 14. A supply pipe 4, a discharge pipe 8 that discharges excess mist lubricant b supplied to the die 14, and a suction device 9 that sucks the mist lubricant b in the supply pipe 4 and the discharge pipe 8 are provided. The mist-like lubricant b is naturally adhered or forcibly applied to the inner wall of the die 14 by a swirling flow or upward flow along the inner wall of the die 14.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 is a system diagram showing the flow of the lubricant according to the embodiment of the present invention, FIG. 2 is a schematic explanatory diagram for introducing the lubricant into the die of the embodiment of the present invention, and FIG. 3 is a powder in the die of the embodiment of the present invention. 4 is a schematic explanatory diagram for molding pellets from a die according to an embodiment of the present invention, FIG. 5 is a schematic explanatory diagram for taking out pellets from a die according to an embodiment of the present invention , and FIG. It is a schematic explanatory drawing which introduces a lubricant into an example die.
[0011]
In forming the pellet A, a stearic acid-based lubricant is adhered and applied to the die 14 of the die holder 15 before the raw powder body a is introduced into the die 14 of the die holder 15. As shown in FIG. 1, the stearic acid-based lubricant is mixed with air in the sprayer 1 to form a mist, and is supplied to the die 14 through the supply pipe 4 through the supply valve 2. At this time, the valve 5 and the valve 7 are opened, and the valve 3 and the valve 6 are closed.
[0012]
The sprayer 1 is provided with an upper lid 19 that covers the upper end of the tank 18, a vibration amplification plate 20 that receives the lubricant supplied to the lower surface of the tank 18, and a vibration amplification plate 20 below the vibration amplification plate 20. A speaker 21 to be vibrated is provided, and a lubricant introduction hole for introducing the lubricant into the tank 18 and a lubricant supply hole for introducing the mist-like lubricant b into the supply pipe 4 are provided. When the lubricant is charged into the tank 18 from the lubricant charging hole, the sprayer 1 operates the speaker 21 to vibrate the vibration amplifying plate 20, and the lubricant on the vibration amplifying plate 20 is mixed with air to form a mist. Then, it is supplied to the supply pipe 4 through the lubricant supply hole.
[0013]
When the mist lubricant b introduced from the supply pipe 4 into the die 14 reaches the die 14, the supply valve 2 and the discharge valve 7 are closed, and the mist lubricant is placed in the lubricant cup 10. Agent b is filled. Thereafter, the outside air suction valve 24 is opened, and the suction force generated when the die holder 15 is raised is forcibly drawn into the die 14.
[0014]
Due to this suction force, the mist-like lubricant b is attached and applied to the inner wall of the die 14 of the die holder 15. When the application of the die holder 15 to the inner wall of the die 14 is completed, the supply valve 5, the outside air suction valve 24, and the discharge valve 7 are opened. The excess mist lubricant b in the die 14 of the die holder 15 and the mist lubricant b in the supply pipe 4 and the discharge pipe 8 are sucked and accumulated in the suction device 9, and this accumulated mist lubricant is collected. b is recirculated into the nebulizer 1.
[0015]
Next, a supply system for the mist lubricant which is another embodiment will be described. The stearic acid-based lubricant is put into the tank 18 of the sprayer 1 and mixed with air to form a mist. The atomized lubricant b which has been atomized by the sprayer 1 is sent to the supply pipe 4 through the supply valve 2. At this time, the valve 3 and the valve 5 are closed, the suction valve 6 is opened, and the suction pipe 9 is once sucked in the supply pipe 4 through the suction pipe 12, and then the suction valve 6 is closed. The supply pipe 4 is filled with the mist lubricant b.
[0016]
When the mist lubricant b supplied from the sprayer 1 reaches the supply pipe 4, the valve 2 is closed, the valve 5 is opened, and the introduction valve 3 is also opened. The compressed air is guided to the supply pipe 4, and the mist lubricant b in the supply pipe 4 is forcibly filled in the dice 14 of the die holder 15 by the pressure of the compressed air, and adheres and is applied to the inner wall of the dice 14. .
[0017]
When the application of the die holder 15 to the inner wall of the die 14 is completed, the introduction valve 3 is closed, and the outside air suction valve 24 and the discharge valve 7 are opened. The excess mist lubricant b in 10 and the mist lubricant b in the supply pipe 4 are sucked and accumulated in the suction device 9, and the accumulated mist lubricant b is recirculated into the sprayer 1. .
[0018]
At this time , as shown in FIG. 6 , the mist lubricant b is sprayed from the injection hole 23 installed on the die 14 to adhere to the inner wall of the die 14 of the die holder 15, and the excess mist lubricant b is added to the die 14. It flows upward and is then recovered. Here, by changing the phase of the injection hole 23 of the die 14, it is possible to set various streamlines such as an upward direction or a swirling flow as a streamline generated on the inner wall of the die 14, and more efficiently. A mist lubricant can be adhered to the inner wall of the die .
[0019]
Thus, although the mist-like lubricant b is supplied, the molding of the pellet A will be described with reference to FIGS. The atomized lubricant b from the sprayer 1 is introduced into the lubricant cup 10. When the lubricant cup 10 is moved to the upper part of the die 14 of the die holder 15 and the die holder 15 is raised until the upper end of the lower punch 13 is positioned below the die 14, the downward suction force generated when the die holder 15 is moved is used. The mist lubricant b in the lubricant cup 10 is attached and applied to the inner wall of the die 14. After the application is completed, excess mist lubricant b in the lubricant cup 10 is sucked by the suction device 9. The upper punch 16 that moves up and down from above in the die 14 of the die holder 15 is positioned above the die 14, the lower punch 13 is fixed, and the die holder 15 moves up and down. (See Figure 2)
[0020]
Next, the lubricant cup 10 is separated from above the die 14 of the die holder 15, and instead the powder body cup 11 into which the powder body a is introduced is moved to the upper part of the die 14, so that the powder body a in the powder body cup 11 is placed on the inner wall. Scrape into the die 14 coated with the lubricant b. At this time, the upper punch 16 is separated from the die 14. (See Figure 3)
[0021]
When the powder body cup 11 is separated from above the die 14 of the die holder 15, the lubricant b is applied to the inner wall, and the upper punch 16 is moved downward from above into the die 14 in which the powder body a is scraped. The die holder 15 is lowered together with the punch 16, the powder body a in the die 14 is compressed by the upper punch 16 and the lower punch 13, and the pellet A is formed from the powder body a. (See Figure 4)
[0022]
Next, the upper punch 16 moves upward, the die holder 15 is lowered, and the pellet A is pushed up to the upper surface of the die 14. (See Figure 5)
[0023]
The pellet A thus molded easily slides inside the die 14 due to the influence of the lubricant b applied to the inner wall of the die 14, and is smoothly pushed up to the upper surface of the die 14 by the lowering of the die holder 15.
[0024]
Experimental example Uses molybdenum as powder and zinc stearate as lubricant.
The amount of the lubricant used was 35 mg with a use amount of 0.05 wt% compared to a use amount of 0.2 wt% of a mixture obtained by mixing a conventional powder body and a lubricant.
As a result,
Conventional mixture is 5.028 g / cc (sintered density), 100% (hardness)
Molded pellets are 5.047 g / cc (sintered density), 125% (hardness)
Therefore, the amount of lubricant used can be greatly reduced, the amount of impurities in the pellets is thereby reduced, the hardness is increased by 25%, and the molding condition is good.
[0025]
Although the embodiments considered to be representative examples of the present invention have been described above, the present invention is not necessarily limited only to the structures of these embodiments, and can be applied to both continuous supply and intermittent supply of lubricant. The supply amount can also be changed by changing the suction time, the speaker frequency of the sprayer, the suction amount, etc., and if there are a plurality of application parts, a plurality of branches can be made, and the above-mentioned configuration requirements according to the present invention are provided. In addition, the object of the present invention can be achieved and modified as appropriate within the scope of the following effects.
[0026]
【The invention's effect】
As is apparent from the above description, the lubricant supply method used in the pellet molding according to the present invention includes a sprayer for atomizing the lubricant and a valve for supplying the sprayed lubricant from the sprayer. And a supply pipe that guides the outside air to the lubricant cup on the die through the outside air suction valve, and a discharge pipe that discharges excess mist lubricant supplied to the die through the discharge valve And a suction device for sucking the mist lubricant in the supply pipe and the discharge pipe, and when the mist lubricant reaches the lubricant cup, the supply valve and the discharge valve are closed, After that, the outside air suction valve is opened, and the mist lubricant is drawn into the die from the lubricant cup by the outside air suction force generated when the die holder ascends, and is naturally adhered or forcibly applied to the inner wall of the die. As That. Also, a sprayer that makes the lubricant into a mist, a supply pipe that guides the mist lubricant from the sprayer to an injection hole installed in the die, and a discharge pipe that discharges excess mist lubricant supplied to the die And a suction device for sucking the mist lubricant in the supply pipe and the discharge pipe, and the mist lubricant is naturally attached to or forcibly applied to the inner wall of the die by a swirling flow or upward flow along the inner wall of the die. Because it is configured, pellets with high purity, high hardness and density, as well as conventional equipment can reduce the cost of equipment such as mixing process and pre-sintering process to mix powder body and lubricant In addition, the lubricant used can be efficiently applied , and the lubricant used can be greatly reduced.
Furthermore, since the mist-like lubricant is attached to the inner wall of the die by the suction force generated when the die is raised, it can be applied more uniformly.
In addition, since the mist-like lubricant is applied by swirling flow or upward flow along the inner wall of the die, it is possible to expect a remarkable effect that the adhesion to the inner wall of the die can be increased and the lubricity can be further improved. It came to.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a flow of a lubricant according to an embodiment of the present invention.
FIG. 2 is a schematic explanatory diagram for introducing a lubricant into a die according to an embodiment of the present invention.
FIG. 3 is a schematic explanatory diagram for introducing a powder body into a die according to an embodiment of the present invention.
FIG. 4 is a schematic explanatory view of molding a pellet from a die according to an embodiment of the present invention.
FIG. 5 is a schematic explanatory view of taking out pellets from a die according to an embodiment of the present invention.
FIG. 6 is a schematic explanatory diagram for introducing a lubricant into a die according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sprayer 2, 3, 5, 6, 7 Valve 4 Supply piping 8 Discharge piping 9 Suction device 10 Lubricant cup 11 Powder body cup 12 Suction piping 13 Lower punch 14 Dice 15 Die holder 16 Upper punch 17 Compressed air introduction tube
23 Injection hole 24 Outside air suction valve A Pellet a Powder body b Atomized lubricant

Claims (2)

A method of supplying a lubricant to a die (14) before molding a pellet (A),
A sprayer (1) for atomizing the lubricant and a lubricant cup (10) on the die (14) through a valve (2) for supplying the sprayed lubricant (b) from the sprayer (1) Supply pipe (4) for sucking outside air through the outside air suction valve (24), and a discharge valve (7) for discharging excess mist lubricant (b) supplied to the die (14). A discharge pipe (8) for discharging through the suction pipe, and a suction device (9) for sucking the mist lubricant (b) in the supply pipe (4) and the discharge pipe (8),
When the atomized lubricant (b) reaches the lubricant cup (10), the supply valve (2) and the discharge valve (7) are closed, and then the outside air suction valve (24) is opened. The mist-like lubricant (b) is drawn into the die (14) from the lubricant cup (10) by the suction force of the outside air generated when the die holder (15) ascends, and naturally flows into the inner wall of the die (14). A method for supplying a lubricant used for pellet molding, characterized by being adhered or forcibly applied. A method of supplying a lubricant to a die (14) before molding a pellet (A),
A sprayer (1) for atomizing the lubricant, a supply pipe (4) for guiding the sprayed lubricant (b) from the sprayer (1) to the injection hole (23) installed in the die (14), and the die The discharge pipe (8) that discharges the excess mist lubricant (b) supplied to (14), and the mist lubricant (b) in the supply pipe (4) and the discharge pipe (8) are sucked. A suction device (9),
Supply of lubricant used for pellet molding, characterized in that mist-like lubricant (b) is naturally attached to or forcedly applied to the inner wall of the die (14) by swirling flow or upward flow along the inner wall of the die (14) Method.

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