JPH01289598A - Powder compacting machine - Google Patents

Abstract

PURPOSE:To prevent the collapse and peeling off of a forming part by automatically feed to the die inner wall the lubrication oil corresponding to the knock-out force of the lower punch in case of compacting the powder of the die inside by pressing with upper and lower punches and knocking out the formed part by the lower punch. CONSTITUTION:The measuring instrument 38 measuring the knock-out force of a lower punch 18 is provided in the knock-out stroke of the lower punch 18 knocking out a formed part 29 from a die 16 and the lubrication oil feeding control device 31 controlling the lubrication oil amt. fed to the inner wall face 16a of the die 16 by the measured value of the measuring instrument 38 is provided. The knock-out force of the lower punch 18 knocking-out the forming part 29 from the die 16 is measured by the measuring instrument 38, e.g., a strain gage or pressure sensitive film, etc., the lubrication oil fed to the inner wall face 16a of the die 16 is adjusted and controlled by this measured value and the feeding amt. of a specified lubrication oil 30 can be controlled according to the kind of the powder. The lubrication oil 30 can thus be coated uniformly on the surface of the forming part 29. The friction force applied on the formed, part 29 is reduced when it is knocked out from the die 16 and no unnecessary force is applied on the forming part 29.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a powder compacting machine, and more particularly to a powder compacting machine for compacting powder metallurgy materials such as fuel pellets for nuclear reactors.

(Prior Art) In general, powder metallurgy materials such as fuel pellets for nuclear reactors are formed by compressing powder supplied into a die using upper and lower punches. As this compression molding machine, a rotary type powder molding machine as shown in FIGS. 5, 6, and 7 is used.

This powder molding machine 10 has upper and lower frames 11 and 12, as shown in FIG. 5, and a vertical shaft 13 is erected between them. A vertical shaft oil receiver 14 is fixed on the upper surface of the lower frame 11 concentrically with the vertical shaft 13, and further above the vertical shaft oil receiver 14, a rotary disk 15 is attached to the vertical shaft 13. It is rotatably mounted.

The rotary disk 15 has an upper flange-like portion 1 on its outer periphery.
5a, the central flange-like part 15b and the lower flange-like part 15c are integrally formed, and the central flange-like part 15
b, a large number of dies 16 are provided in the circumferential direction with the same diameter as shown in FIG. Also, the upper flange-like part 1
5a is provided with an upper bunch 17 movable up and down on the same axis as each die 16, and a lower bunch 18 is also disposed on the lower flan-shaped portion 15c so as to be movable up and down on the same axis as each die 16. A drive gear 20 driven by an appropriate drive mechanism is meshed with the gear [9] formed on the outer periphery of the lower flange-shaped portion 15c.

On the other hand, a guide roller 21 is attached to the lower bunch 18 on the outside of a portion protruding downward from the rotary disk 15, and the guide roller 21 is disposed on the frame 11 over a predetermined range in the circumferential direction. It is engaged with the guide groove 22. Further, guide rollers 23 are installed on both sides of the portion of the upper punch 17 that protrudes upward from the rotary disk 15, and are engaged with guide grooves 24 disposed over a predetermined range in the circumferential direction at a position above the rotary disk 15. are combined.

In addition, the upper punch air and the lower punch 18 are inserted into the die 1.
A pressurizing stroke section (Fig. 6,
(see FIG. 7), pressure rollers 25 and 26 are disposed, respectively, in contact with the top end of the upper bunch 17 and the bottom end of the lower punch 18, and apply pressure to both punches.

In FIG. 5, reference numeral 27 is a powder feeder, and 28 is a mechanism for taking out the molded product 29.

Therefore, when compression molding the powder M, the drive gear 20
The rotary disk 15 is rotated through the rotary disk 15, and the powder M from the powder feeder 27 is supplied into the die 16 which has come to a predetermined position (see FIG. 7). Therefore, in accordance with the rotation of the rotary disk 15, the guide groove 22 and the guide roller 2
1, the lower punch 18 is moved up to a predetermined filling depth, and the excess powder M is removed (see Fig. 7 ■). The powder M inside is held between the upper and lower punches 17 and 18 (see FIG. 7). In this way, dice 16
The upper and lower punches 17 and 18 hold the powder M inside.
When the powder M enters between the pressure rollers 25, 26, the upper and lower punches 17, 18 are pressed toward each other by the pressure roller 25, 26, and compression molding of the powder M is performed (Fig. 7). ■Reference). In this manner, when the pressurizing stroke is completed, the lower punch 18 is moved upward, and two molded products are extruded (see FIG. 7 (2)).

Thereafter, compression molding of the powder M is sequentially performed within each die 16 in the same manner.

(Problem to be solved by the invention) By the way, when pressurizing powder in such a powder compacting machine, the particle size, shape, wettability, etc. differ depending on the type of powder, so the stress applied to the upper and lower punches and the friction between the particles are different. make them different. Therefore, in order to obtain a predetermined powder molded product, it is necessary to adjust the molding pressure, molding speed, etc. However, even if the molding pressure, molding speed, etc. are adjusted, depending on the powder, the frictional resistance between the inner wall of the die and the molded product is so large that it becomes impossible to press the upper and lower punches, making molding impossible.

Conventionally, a certain amount of lubricating oil is supplied to the inner wall of the die or into the powder to reduce the frictional resistance applied to the molded product.

That's what I was doing. However, in this method, as mentioned above, the particle size etc. differ depending on the powder, so if only a certain amount of lubricating oil is supplied, the lubricating oil on the surface of the molded product, that is, the state of the lubricating oil applied may be uneven, or it may be too much or too little. Then a phenomenon occurs. In this case, there is a problem in that if too much lubricating oil is applied, the end face of the molded product collapses, and if too little is applied, the end face of the molded product is peeled off.

SUMMARY OF THE INVENTION An object of the present invention is to provide a powder molding machine that supplies an appropriate amount of lubricating oil to the inner wall of the die depending on the type of powder, thereby preventing molded products from collapsing or peeling.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a powder molding machine in which powder supplied into a die is compressed and formed by upper and lower punches, and a molded product is extruded from the die by a lower punch. A measuring device is provided to measure the pushing force applied to the lower punch during the process of extruding the molded product from the die by the punch, and the amount of lubricating oil supplied to the inner wall surface of the die is determined based on the measurement value of the measuring device. A lubricating oil supply control device is provided to control the lubricating oil supply, and a strain gauge or a pressure-sensitive film is used as the measuring device.

(Function) The extrusion force of the lower punch that extrudes the molded product from the die is measured by a measuring device such as a strain meter or a pressure-sensitive film, and the amount of lubricating oil supplied to the inner wall of the die is adjusted and controlled based on this measurement value. A predetermined lubricating oil is supplied to the inner wall surface of the die depending on the type of die.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the die 16 in the powder compacting machine CO-0 of the present invention.
FIG. 3 is a schematic diagram of a lubricating oil supply mechanism 31 that supplies lubricating oil 30 to an inner wall surface 16a of the vehicle. This lubricating oil supply mechanism 31 is provided with a tank 32 containing lubricating oil 30, and this tank 32 has a predetermined lubricating oil 30 in a lubricating oil supply pipe 33.
A pump 34, pressure potash, and a leaf valve 35 are provided. The lubricating oil supply pipe 33 is provided with a micro-adjustment valve 36, and a total of one constant device, for example, a strain gauge 38, is provided in the push-up track 37 of the pressure roller 26.
The opening degree of the fine adjustment valve 36 is adjusted and controlled according to the strain force of the fine adjustment valve 36. The lubricating oil supply pipe 33
is connected to a vertical hole 39 extending in the axial direction formed at the center of the lower bunch 18, and a horizontal hole 41 communicating with the top end of the vertical hole 39 is connected to a constricted portion 40 at the upper part of the lower punch 18.
It is opened to

lff of the fine adjustment valve 36 of the lubricating oil supply pipe 33
Control is performed as follows.

Generally, the gap between the inner wall surface 16a of the die 16 and the upper and lower punches is 20 μm, and when the molded product 29 is extruded from the die 16, the molded product 29 expands by 1 to 2% compared to the inner diameter of the die 16.

With the die 16 and the two molded products having this relationship, the extrusion force, that is, the friction state, when the two molded products are extruded from the die 16 by the lower bunch 18 is detected, and the value is supplied to the inner wall surface 16a of the die 16. The amount of lubricating oil 30 supplied can be controlled.

On the other hand, as shown in FIG. 2, the force in the radial direction of the die 16 is
Assuming that r is the pressing force from the upper punch 17 and Fu is the pressing force from the upper punch 17, these can be expressed by the following formula.

F r -ν/ (1-ν) F u -...
...(1) Here, C is the Poissot ratio.

Further, when the upper bunch 17 presses the two molded products with a pressing force Fu, a frictional force, that is, a reaction force Fd appears on the die inner wall surface 16a. Here, if Fl is the push-up force from the lower punch 18, fw is the die wall friction force, μW is the die wall friction coefficient, fi is the interparticle friction force, and μl is the interparticle friction coefficient, the following relational expression holds true. .

Fu−FΩ+F d ・=・(2) Also, F d −f w+ fi −(3
)-F r ・μw+F r-μl ・・・・・・(
4)-Fr(μW+μi)...(5)(2
) and (5), we get Fu −, F, Q +F r (μw+μi) −(
6) Here, the die wall friction coefficient μW is changed by the amount of lubrication/ItI30 supplied to the die inner wall 6a, that is, the application state of the two molded products. This die wall friction coefficient μ
The change in W is captured by the distortion: 138 and 17, and the opening degree of the fine adjustment valve 36 of the lubricating oil supply pipe 33 is adjusted and controlled from this value.

In FIG. 1, a strain gauge 38 provided in the push-up track 37 of the pressure roller 26 is connected to a bridge circuit (not shown), and the strain is extracted from the output of this bridge circuit. Here, the initial resistance value of the strain meter 38 is R, the resistance change due to strain is ΔR5, the gauge factor is 1, the voltage applied to the bridge circuit is E1, the strain is 5, and the change in output voltage is Δe.
If o, the following relationship generally holds true.

ΔR/R-K・ε...(7) Also,
The output voltage of the bridge circuit is Δeo-ΔR/R-E-1(K・ε)E...(8) If the applied voltage E is constant, the strain is the extrusion pressure F.
It can be extracted as a voltage signal ΔeO proportional to Ω.

The opening degree of the minute A control valve 36 is adjusted and controlled by the voltage signal Δeo detected in this way. Therefore, the pump 34
When the lubricating oil 30 is driven, the lubricating oil 30 is supplied to the inner wall 16a of the die 16 through the fine adjustment valve 36 whose opening degree is controlled, the pipe 33, and the hole 39. A lubricating oil 30 corresponding to the force for pushing up the powder, that is, the friction between the two molded products, is supplied, and extrusion molding can be performed appropriate to the type, nature, and characteristics of the powder.

Fig. 3 shows an example of strain kg/cf and valve opening degree measured in this way, and Fig. 4 shows an example of strain kg/cf and valve opening degree measured in this way.
The state of lubricating oil applied to the molded product 29 was optically detected and expressed as an oscillograph. Figure 4a shows the molded product obtained by the molding machine of the present invention; , shows a molded product obtained by a conventional molding machine. As is clear from these results, it can be seen that lubricating oil is applied more uniformly to molded products produced by the molding machine of the present invention than to conventional molded products.

In the molding machine of the present invention, a strain meter is used to detect the pushing force of the lower bunch 18, but a change in color tone of the pressure-sensitive film may be used instead. Furthermore, by combining the strain gauge or pressure-sensitive film with an optical device, even more accurate hydraulic control can be achieved.

〔Effect of the invention〕

The molding machine of the present invention automatically supplies lubricating oil to the inner wall of the die according to the pushing force of the lower punch when the powder in the die is pressed and molded by the upper and lower punches and the molded product is extruded by the lower punch. This allows the lubricating oil to be evenly applied to the surface of the molded product to a thickness of several micrometers. Therefore, there is no need to perform troublesome operations such as adjusting the lubricating oil each time.

In addition, since lubricating oil is uniformly applied to the surface of the molded product,
Since the frictional force applied to the molded product when extruding it from the die is reduced and unnecessary force is not applied to the molded product, the quality of the molded product, especially cracking, chipping, and crumbling, can be reduced.

In addition, since the molding machine of the present invention controls the supply of lubricating oil during the process of pushing up the molded product, it is possible to supply the optimal lubricating oil depending on the type, nature, characteristics, etc. of the powder being molded. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing the hydraulic pressure supply pipe line of the powder compacting machine of the present invention, FIG. 2 is an enlarged cross-sectional view of the main part of FIG. 1 and shows its operation, and FIG. Figure 4 (a) and (b) are characteristic diagrams showing the state of application of lubricating oil on molded products, and Figure 5 is a characteristic diagram for controlling the hydraulic pressure supply pipe line. 6 is a sectional view of the main part of FIG. 5 taken along line A-A and viewed in the direction of the arrow. FIG. 7 is a sectional view of the main part of FIG. FIG. 10...Powder molding machine, 11...Lower frame, 12.
・Upper frame, 13... Vertical shaft, 14... Vertical shaft oil pan, 15... Turntable, 16... Die, 1
7. Upper bunch, 18. Lower punch, 19. Gear,
20... Drive gear, 21. ...Guide roller, 22.
...Guide groove, 23...Guide roller, 24...Guide groove, 25.26...Pressure roller, 27...Powder feeder, 30...Lubricating oil, 31...Lubricating oil supply Mechanism, 3
2...tank, 33...lubricating oil supply pipe, 34...
・Pump, 35...Pressure relief valve, 36...
Fine ff12 adjustment valve, 37... Push-up orbit, 38...
Strain meter, 39.41... hole, 40... constriction. Applicant's agent Sato - Yukon 1 Tsuko 2 Zuko h (Kg/cm2+ Shima 3 Tsuo 6 Trap 4 Fig. (0) Akira 4 Fig. (b) Calving 5 Fig.

Claims (1)

[Claims] 1. In a powder molding machine in which powder supplied into a die is compressed and formed by upper and lower punches, and the molded product is extruded from the die by a lower punch, the molded product is extruded from the die. A lubricating oil supply control device that includes a measuring device that measures the pushing force of the lower punch during the extrusion stroke of the lower punch, and controls the amount of lubricating oil supplied to the inner wall surface of the die based on the measured value of the measuring device. A powder molding machine characterized by being provided with. 2. The powder compacting machine according to claim 1, wherein the measuring device is a strain gauge. 3. The powder molding machine according to claim 1, wherein the measuring device is a pressure-sensitive film.