JPS63242498A - Rotary press for powder compression molding - Google Patents

Abstract

PURPOSE:To provide the rotary press for compression molding a powder capable of the simultaneous molding of dissimilar materials in the case of a molding stage, made by composing so as to simultaneously mold by each die set of a large, small diameter parts by ascending and descending the upper and lower punches inside each die by synchronizing with the rotation by guiding them with a fixed cam ring. CONSTITUTION:Excepting fixed cam rings 5a, 5b, the upper and lower punches 3a, 3b, 4a, 4b for each die 2a, 2b of a larger diameter part 1a and small diameter part 1b and a rotary table 1 are rotated together. And the upper and lower punches 3a, 3b, 4a, 4b for each die 2a, 2b are ascended and descended by synchronizing with the rotation by guiding with the cam rings 5a, 5b to simultaneously perform the molding by each die set of the large diameter part 1a and small diameter part 1b. In this case, the line of molding dies 2a, 2b becomes in plural lines of the large diameter part 1a and small diameter part 1b and yet the die upper face height of these each line varies. The mixture of a powder material can be avoided by varying the height levels of the application faces of the feeding mechanism and sucking recovery mechanism of the powder material.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a rotary press for compression molding powder, and in particular, a rotary press suitable for molding compacted bodies (green pellets) before sintering nuclear fuel pellets. This paper relates to improvements to powder molding presses.

[Conventional technology]

As is well known, era uranium pellets I. of several types of R shrinkage are normally used as fuel for boiling water reactors for reasons of core design.

Conventionally, in the molding of such fuel pellets, as shown in Japanese Patent Publication No. 56-27360, for example, a plurality of upper and lower punches and a plurality of molding dies constituting a die set with each of these punches are connected to the periphery. It is equipped with a rotary table arranged at equal intervals on the same circumference in the vicinity, and while each of the upper and lower punches and the rotary table are rotated together, the upper and lower punches are periodically raised and lowered by being guided by a fixed cam ring. A type of rotary press was used. In such a conventional rotary press, there is only one rotary table and its die set has a single circular row configuration, so it is difficult to simultaneously mold pellets of different concentrations. This was virtually impossible due to mechanical constraints in feeding and taking out the formed pellets.

[Problem that the invention seeks to solve]

In the production of multiple trays of fuel pellets with different a degrees of compaction, M1-class control has conventionally been carried out for each enrichment degree, and measures have been taken to strictly avoid mixing of fuel pellets with different enrichment degrees.

This procedure is no exception in the press forming of green pellets before pellet sintering. Conventionally, there is one rotary table and a die set in a single row configuration, so when forming pellets with several different concentrations, it is necessary to The molding press must be completely re-leaned every time the pressure is changed, which has been an obstacle to reducing pellet production costs.

Therefore, an object of the present invention is to provide a rotary press for powder compression molding that is capable of simultaneously molding different materials such as fuel pellets of different concentrations, in which mixing of materials and molded products must be avoided during the molding process. There is a particular thing.

[Means for solving problems]

According to the present invention, the rotary table includes a plurality of upper and lower punches, and a rotary table in which each of these punches and a plurality of molding dies constituting a die set are arranged at equal intervals on the same circumference near the periphery, and In the four-creep press, the upper and lower punches are periodically raised and lowered by a fixed cam ring while the punch and the rotary table rotate together, and the rotary table has a large diameter part and a small diameter part. The upper surface of the small diameter portion has a higher top surface level than the top surface of the small diameter portion, and the row of forming dies is arranged in the large diameter portion, and another plurality of similar circular rows of forming dies are arranged near the periphery of the small diameter portion. Provided is a low-pressure press for powder compression molding characterized by a coaxial arrangement.

In one preferred embodiment of the present invention, the row of molding dies in the large diameter portion and the row of molding dies in the small diameter portion are arranged concentrically.

According to another preferred embodiment, the fixed cam ring includes a first cam ring fixedly arranged inside the row of molding dies on the upper surface of the small diameter part, and a first cam ring fixedly arranged on the outer periphery of the small diameter part. two cam rings, such that the vertical movement of the upper punch for the forming die in the small diameter portion is guided by the first cam ring, and the vertical movement of the upper punch for the forming die in the large diameter portion is guided by the second cam ring. It has become.

[Effect]

In the rotary press of the present invention, except for the fixed cam ring, the upper and lower punches for the large and small diameter dies and the rotary table rotate together, and the upper and lower punches for each die are guided by the fixed cam ring and synchronized with the rotation. The large-diameter portion and the small-diameter portion are simultaneously molded using die sets. In this case, as mentioned above, there are multiple rows of molding dies with large diameter parts and small diameter parts, and the top surface heights of the dies in each row are different, so the powder material supply mechanism and suction The height level of the application surface of the collection mechanism is made different to avoid contamination of powder material, and the molded pellets can also be taken out independently from the large diameter part and the small diameter part at different positions in the radial direction.

In order to further clarify the above-mentioned features and advantages of the present invention,
Embodiments of the present invention will be described below with reference to the drawings.

〔Example〕

FIG. 1 is a block diagram showing the general structure of a rotary press according to an embodiment of the present invention, and FIG. 2 is a schematic plan view of the rotary table portion thereof.

In the figure, the rotary table 1 consists of a three-stage circular table consisting of a large-diameter portion 1a, a small-diameter portion 1b above it, and a central convex portion IC above the large-diameter portion 1a. Ten forming dies 2a are arranged at equal intervals on the same circumference, and seven forming dies 2b are arranged at equal intervals on another same circumference on the small diameter portion 1b. ing. Each forming die 2a, 2b has an upper punch 3a, 3b and a lower punch 4, as shown in FIG.
a and 4b are provided, and these form die sets equal to the number of molding dies, and these die sets rotate together with the rotary table 1. Upper punch 3a
A fixed cam ring 5a is disposed on the outer periphery of the small diameter portion 1b supported by a non-rotating member (not shown) to guide the elevation of the upper punch 3b. A fixed cam ring 5 is attached to the outer periphery of the portion 1c.
b is supported by a non-rotating member (not shown). The upper punches 3a, 3b have their bases 6a.

6b has rollers 7a and 7b, and this roller 78°7b
The cam surfaces of the cam rings 5a and 5b are shifted to cause the punch to move up and down in accordance with the cam curve while the table 1 is rotating.

Similar fixed cam rings are also provided for the lower punches 4a and 4b, but since these are redundant, their explanation will be omitted. In addition, the powder material supply section and forming bellet)
For the take-out part, furthermore, the press lowering mechanism of the upper and lower punches, etc., the same ones as those described in the above-mentioned Japanese Patent Publication No. 56-27360 may be used. The only difference is that they are installed independently from the die 2b of the small diameter portion 1b.

The 360 degree rotation angle range of the rotary table 1 is divided into several sections, and the filling section of the powder material into the dies 2a and 2b, the compression molding section using the upper and lower punches, the taking out section of the molded pellets, etc. are set in order, and the processing is performed accordingly. The cam curves of the fixed cam rings 5a and 5b are determined in advance so as to allow the upper and lower punches to move up and down.

In the illustrated example, a + side forming die 2a is provided in the large diameter portion In, and seven forming dies 2b are provided in the small diameter portion 1b.
Therefore, ten sets of upper and lower punches are provided for the large diameter portion and seven sets for the small diameter portion, and all of these rotate together with the rotary table 1. As the table 1 rotates, the cam ring 5a
, 5b, the upper punch 3a in the powder material supply section.

3b is retracted above the die, and a powder material, for example, a nuclear fuel material containing uranium dioxide, is supplied and filled into the die whose bottom is closed by lower punches 4a and 4b.

Then, as the table 1 rotates, the upper punch 3a is released.

3b and the lower punches 4a and 4b approach each other, and the upper and lower punches are forcibly rolled down by a roll or the like at a rolling down device, and the powder material in the die is compressed.

Further, as the table 1 rotates, the upper and lower punches are raised together, and after the molded product is extruded to the upper surface of the die, the large diameter portion and the small diameter portion are collected separately using a scraper or the like. Thereafter, when an empty die or a powder material supply section is reached by further rotation of the table 1, the upper and lower punches are brought back to their original standby positions for material supply. In this way, powder material is supplied to each large and small diameter section independently using bells and bells of different heights, and one rotation of the table 1 supplies powder to the large and small diameter sections on the positive side and seven on the small diameter section. The molded parts are removed separately at different height levels, so that continuous molding of different materials is possible without fear of contamination with one another. In this case, by setting the powder material supply position and the molded product removal position for the large diameter part and the small diameter part at rotation angle positions that are shifted by 180 degrees, for example, mixing of the two can be more effectively avoided. become able to.

In the embodiment described above, the circular row of forming dies is arranged in one row for the large diameter part and one for the small diameter part, but the present invention is not limited to this example; There is no problem in providing a plurality of rows, or providing an even larger number of stages of different diameter sections, and providing an arbitrary number of rows of forming dies on each diameter section.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to simultaneously perform powder compression molding of different materials with one device without fear of mixing with each other, and there is no need to perform cleaning in between. This has the effect of reducing costs and making effective use of space. In addition, when the rotary press of the present invention is used for forming nuclear fuel pellets, the number of die sets for each diameter section with different heights is appropriately determined,
- It is also possible to form all types of fuel pellets required for a fuel assembly in one operation using one device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the general structure of a rotary press according to an embodiment of the present invention, and FIG. 2 is a schematic plan view of the rotary table portion thereof. In the drawings, the same reference numerals indicate the same or equivalent parts; 1 is a rotary table, 1a is a large diameter part, 1b is a small diameter part, 1c is a central convex part, 2a and 2b are molding dies, and 3a. 3b is an upper punch, 4a and 4b are lower punches, and 5a. 5b is a fixed cam ring, 6a and 6b are upper punch bases, 7
a and 7b are rollers.

Claims (1)

[Claims] 1. A rotary table comprising a plurality of upper and lower punches, and a rotary table in which each of these punches and a plurality of molding dies constituting a die set are arranged at equal intervals on the same circumference near the periphery, The upper and lower punches and the rotary table are rotated together and the upper and lower punches are periodically raised and lowered under the guidance of a fixed cam ring, wherein the rotary table has a large diameter part and a small diameter part, and the rotary table has a large diameter part and a small diameter part. The top surface of the small diameter portion has a higher top surface level than the top surface, and the row of forming dies is arranged in the large diameter portion, and another plurality of similar circular rows of forming dies are coaxially arranged near the periphery of the small diameter portion. A rotary press for powder compression molding characterized by the following: 2. The rotary press for powder compression molding according to claim 1, wherein the row of molding dies in the large diameter portion and the row of molding dies in the small diameter portion are coaxial. 3. The fixed cam ring includes a first cam ring fixedly arranged inside the row of molding dies on the upper surface of the small diameter part, and a second cam ring fixedly arranged on the outer periphery of the small diameter part, The upper punch for the forming die is raised and lowered in the first
Powder compression according to claim 1, characterized in that the powder compression is guided by a cam ring, and the upper punch for the forming die of the large diameter portion is guided up and down by the second cam ring. Rotary press for molding.