JPH0522398Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a powder forming apparatus for forming powder metallurgy materials such as fuel pellets for nuclear reactors.

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

In other words, in a rotary powder molding machine for performing compression molding as described above, a large number of dies are arranged in the circumferential direction on a rotary disk that is rotatably mounted on a rigid shaft. The powder supplied into the die is press-molded by an upper punch and a lower punch arranged on the same axis as the die.

That is, FIG. 2 is a developed view showing each molding process of the powder molding machine, in which upper punches 3 are located on the same axis as a plurality of dies 2 provided in the circumferential direction on the outer periphery of the rotary disk 1. , and a lower punch 4 are arranged to be movable up and down. Therefore, pressurization stroke A
Subsequently, a molded product extrusion process B, a molded product discharging process C, a powder filling process D, a weight adjustment process E, and a pressurization preparation process F are sequentially repeated.

By the way, when pressure forming is performed in the die 2 by the upper punch 3 and the lower punch 4 as described above, the differential transformer 8 connected to the lower pressure roller 6
The change in the dimensions of the pellet is measured, and if the length is out of a predetermined range, a control signal is input from the feedback circuit 9 to the filling amount adjustment cam drive motor 10, and the filling amount adjustment cam 11 is moved up and down. Adjustments can be made to change the powder loading amount.

(Problem to be solved by the invention) However, in the above-mentioned device, the depth of the lower punch during powder filling is controlled by changing the dimensions of the pellet, but it is difficult to control the weight of the powder filled in the die. It's not something to measure.

Therefore, there is no way of knowing whether the powder has been filled within a certain variation within the die.
As a result, variations occur in the powder filling amount, resulting in variations in molding height and density, etc.
In some cases, there are problems such as non-standard products being produced.

In view of these points, the present invention is a powder molding method that can control the amount of powder filling at a constant constant and reduce or eliminate the occurrence of defective products in terms of the height and density of the molded product. The purpose is to obtain equipment.

[Structure of the idea]

(Means for Solving the Problems) The present invention provides a rotary powder molding device having a plurality of dies and punches in the circumferential direction, and a weight detector that measures the weight of each molded pellet, and a weight detector that measures the weight of each molded pellet. The present invention is characterized by comprising a calculation device that calculates the variation in the weight of the molded pellets based on the weight signal detected by the pellets, and a feedback circuit that changes the rotational speed of the rotary disk when the variation exceeds a predetermined range.

(Function) The weight of the molded pellets discharged from the powder molding device is detected by a weight detector one by one or on a sampling basis, and when the variation in weight of each molded pellet exceeds a predetermined range, the feedback circuit is activated. The rotational speed of the rotary disk is changed, the time for powder filling is set to an appropriate value, and variations in powder filling are prevented.

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

Reference numeral 1 in the figure is a frame, and a vertical shaft 22 is erected between the frame 20 and a stand frame 21 provided above the frame 20. A vertical shaft bearing 23 is fixed on the upper surface of the frame 20 concentrically with the vertical shaft 22, and further above the vertical shaft bearing 23, a rotary disk 24 is arranged to rotate with respect to the vertical shaft 22. It is attached freely.

The rotary disk 24 has an upper flange portion 24a, a center flange portion 24b, and a lower flange portion 24c integrally formed on its outer periphery, and the center flange portion 24b has a large number of flange portions arranged in the circumferential direction. A die 25 is provided. Further, an upper punch holder 26 that holds an upper punch 26a on the same axis as each of the dies 25 is vertically movably arranged on the upper flange-shaped portion 24a, and the lower flange-shaped portion 24c also has an upper punch holder 26 that holds an upper punch 26a on the same axis as each of the dies 25. A lower punch holder 27 holding a lower punch 27a is disposed on the same axis as the lower punch holder 27 so as to be movable up and down, and is further driven by a drive motor 29 to a gear 28 formed on the outer periphery of the lower flange-shaped portion 24c. A drive gear 30 is meshed.

On the other hand, the lower punch holder 27 is provided with a guide roller 31 on the outside at a portion protruding downward from the rotary disk 24.
is engaged with a guide groove 32 disposed on the frame 20 over a predetermined range in the circumferential direction. Further, guide rollers 3 are provided on both sides of the portion of the upper punch holder 26 that protrudes upward from the rotary disk 24.
3 is attached and engaged with a guide groove 34 disposed over a predetermined range in the circumferential direction at a position above the rotary disk 24.

In addition, the upper punch 26a and the lower punch 27
a is inserted into the die 25 from above and below, and in the pressurizing stroke part where the powder raw material supplied into the die 25 is compressed and molded, a is brought into contact with the top end of the upper punch holder 26 and the bottom end of the lower punch holder 27, respectively, Pressure rollers 35 and 36 are provided to apply pressure to both punches, respectively. Note that the reference numeral 37 in FIG. 11 is a powder feeder.

Thus, when compressing powder, the rotary disk 24 is rotated via the drive gear 30, and at the same time, the powder is fed from the powder feeder 37 into the die 25 which has come to a predetermined position. Here, in accordance with the rotation of the rotary disk 24, the lower punch 27a is moved upward via the guide groove 32 and the guide roller 31 to reach a predetermined filling depth, and after removing excess powder, the upper punch 27a The punch 26a is gradually processed, and the powder inside the die 25 is transferred to both the upper and lower punches 26.
It is sandwiched between a and 27a. When the upper and lower punches 26a and 27a, which are holding the powder in the die 25 in this manner, enter between the pressure rollers 35 and 36, the upper and lower punches 26a and 27a are pushed together by the pressure rollers 35 and 36. The powder is pressed in the approaching direction and compression molding of the powder is performed.

When the pressurizing process is completed in this way, the upper and lower punches 26a and 27a move the upper and lower punches upward with the molded product being held between them, so that the upper surface of the lower punch 27a is flush with the upper surface of the die 25. At the point when the molded product is used, the upper punch 26a is moved further upward, and then the molded product is delivered.
Thereafter, compression molding of powder is sequentially performed within each die 25 in the same manner.

By the way, the pellets formed by compression molding of the powder as described above are transferred to the conveyor 3 by a scraper (not shown) at the delivery position.
8 is paid out consecutively. A weight detector 39 connected to a weight balance is provided in the middle of the conveyor 38, and the weight of the continuously conveyed pellets P is sequentially measured one by one by the weight detector 39. It's like this.

The detection signal from the weight detector 39 is input to a weight data calculation CPU 40, where the weight variation of each pellet P is calculated. When this variation exceeds a certain predetermined range, this signal is input to the feedback circuit 41, the motor 29 is controlled by the output signal, and the rotational speed of the rotary disk 24 is adjusted. That is, by slowing down the rotational speed of the rotary disk 24, the powder supply time into the die 25 is lengthened, and the powder filling capacity is changed.

In this manner, by controlling the variation in the weight of the pellets and the rotational speed of the rotary disk, the rotary disk is always rotated at maximum efficiency.

[Effect of idea]

As explained above, in the present invention, the powder filling time is adjusted by detecting the weight of each pellet and adjusting the speed of the rotary disk according to the dispersion in weight. Basically, the variation in the amount filled into each die is reduced, the quality of the pellet product can be made uniform, and the occurrence of defective products can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of the powder compacting device of the present invention.
FIG. 2 is a developed view showing a conventional powder compacting device. 24... Turntable, 25... Dice, 26a...
Upper punch, 27a...Lower punch, 29...Motor, 35, 36...Pressure roll, 38...Transport conveyor, 39...Weight detector, 40...CPU for calculating weight data, 41...Feedback circuit .

Claims (1)

[Scope of utility model registration request] In a rotary powder compacting device having a plurality of dies and punches in the circumferential direction, there is a weight detector that measures the weight of each shaped pellet, and the weight of the shaped pellet is determined by the weight signal detected by the detector. 1. A powder molding apparatus, comprising: a calculation device for calculating the variation in the powder; and a feedback circuit for changing the rotational speed of the rotary disk when the variation exceeds a predetermined range.