JPH0790529B2 - Pressure molding method of bottomed cylindrical kneaded product - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for press-molding a kneaded product so as to obtain a bottomed tubular molded body.

(Prior Art) Generally, as a method for manufacturing a bottomed cylindrical ceramic,
There are a method of extruding the kneaded clay, a method of casting and molding the mud, a method of press-molding the powder and the like.

For example, when a bottomed cylindrical porous ceramic filter for filtering a liquid is produced, the kneaded material is pressure-formed into a bottomed cylindrical body having a size of, for example, length: 94 mm, outer diameter 34 mm, and inner diameter 20 mm. To do. An example of this device is shown in FIG.

This pressure molding apparatus fills the inside of the outer mold 1 with the kneaded material,
After lowering and pressing the middle mold 2 from above, the middle mold 2 is raised, the outer mold 1 is divided into 1a and 1b, and the bottomed cylindrical molded body is extracted from the cylindrical hole 1c of the outer mold 1. Is.

(Problems to be Solved by the Invention) However, according to such a conventional pressure-molding apparatus for a bottomed tubular kneaded material, it is possible to perform die-cutting after pressurization based on the shape of a molded article having a bottomed tubular body. Since it is not easy and it is difficult to release the molded product, there are the following problems.

For example, as shown in FIG. 4 (a), the molded product (kneaded clay) 3 is likely to adhere to the outer peripheral surface of the cylindrical middle mold, and the molded product 3 cannot be removed from the middle mold 2.

As shown in FIG. 4 (b), since the molded product 3 is easily adhered to the inner peripheral surface of the outer mold 1, when the outer mold 1a and the outer mold 1b are divided and released in the direction of the arrow, the molded product 3 is deformed. Or cracks will occur.

As shown in FIG. 4C, when the middle mold 2 is lifted in the direction of the arrow when the middle mold 2 is released, the inside of the cylinder of the molded product 3 and the middle mold 2 are
During this period, a vacuum portion V is generated and a recess 3a is formed on the outside of the molded product 3, resulting in a defective R shape of the tip of the molded product.

The present invention has been made to solve such a problem, and improves the releasability at the time of pressure molding and has a bottomed cylindrical shape with high dimensional accuracy without damaging the recess or R shape of the molded product. It is an object of the present invention to provide a method for pressure-molding a bottomed cylindrical kneaded product, which is capable of producing the molded product of 1. with high production efficiency.

(Means for Solving the Problems) Therefore, the method for pressure-molding a cylindrical kneaded product with a bottom according to the present invention includes an outer die having a cylindrical hole with a bottom inside, and a rotary insertable into the cylindrical hole. A medium-sized body having an equilateral surface and an arcuate surface formed on the outer peripheral surface of the rotating body, or a medium-sized body having a curved surface whose outer diameter is gradually reduced in the circumferential direction on the outer peripheral surface of the cylindrical body, Preliminarily rotationally driven, the kneaded product filled in the bottomed cylindrical hole is pressure-molded by moving forward in the pressing direction while rotating the middle mold, and then the middle mold is rotated from the kneaded product. Meanwhile, the intermediate mold is extracted from the outer mold by returning in the counter-pressing direction.

Here, as the kneaded material, oxides such as aluminum, zirconium and titanium, ceramics such as carbides and nitrides, glass such as borosilicate glass, metals such as nickel and the like can be applied.

(Operation) According to the method for pressure-molding a bottomed tubular kneaded product of the present invention, since the middle die is rotated and the air vent recess is provided on the outer peripheral surface of the middle die, the air vent recess is removed from the air vent when the middle die is released. Since the air escapes, it is possible to improve the air release property of the kneaded product packed in the outer cylindrical hole without generating a vacuum portion, and to enhance the releasability of the bottomed cylindrical molded body.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows a pressure molding apparatus, in which 5 is an outer mold and 6 is a middle mold. The outer die 5 is a half-division type of the outer die 5a and the outer die 5b, and has a cylindrical hole 7 inside and a stepped large-diameter hole 8 at the upper part of the cylindrical hole. Medium 6 is outer 5
Can be inserted into the cylindrical hole 7 and the tip 6a has a hemispherical convex surface.

As shown in FIG. 2 (c), the main body of the medium-sized mold 6 shown in FIG. 1 has a basic cross-section of a substantially regular hexagon, and six equilateral faces 9 are provided inside the circumscribed circle of the regular hexagon. R is added to the boundary between the adjacent equilateral side faces 9, and these equilateral side faces 9 form an air vent concave portion with respect to the circumscribed circle.

The pressure molding method will be described with reference to FIG.
The kneaded soil is put into the cylindrical hole 7 inside the outer mold 5, and the middle mold 6 is lowered while rotating in the direction of the arrow A in the first figure from above the kneaded soil, and after pressing, the middle mold 6 is raised while rotating. After that, the outer die 5 is divided into an outer die 5a and an outer die 5b, and the outer die 5
Remove the molded product from the inside.

In this case, when the middle mold 6 is lowered, the excess kneading soil is discharged through the air vent recesses provided in the middle mold, so that the molding pressure acts uniformly. Further, since the middle die 6 is lifted while being rotated and pulled out, air is released along the equilateral surface 9. That is,
Unlike the case where there is no air vent recess, the interface between the medium mold and the molded body does not stick to the moisture in the kneaded soil or become a vacuum state. Therefore, the molded product does not adhere to the middle mold 6. Further, since the molded body is not subjected to excessive force, the core of the molded product is small and the dimensional accuracy is good. Furthermore, when the outer mold 5a and the outer mold 5b are divided after pressure molding, no dents, R-shaped defects, cracks or the like occur in the molded product.

Next, as another embodiment of the present invention, modified examples of the cross-sectional shape of the middle die 6 are shown in FIGS. 2 (d), (e) and (f). (D) is a medium-sized cylindrical outer peripheral surface with three equilateral sides 10 and circular arc surfaces 14 formed at 120 ° intervals, and (e) is an outer peripheral surface of a medium-sized cylindrical body at 90 ° intervals. The side is an equilateral surface 11 and a circular arc surface 15 are formed. Further, (f) is a curved surface 12 whose outer diameter is gradually reduced in the circumferential direction on the outer peripheral surface of the cylindrical body of the medium size 6 at regular intervals of 90 °. It was formed.

As a comparative example, (a) is a medium-sized mold 6 having a circular cross section, (b)
Is a medium mold 6 having a circular cross section and two grooves 13 and 14 formed in the diameter direction.

Next, the examples and comparative examples shown in FIG. 2 are classified according to the presence / absence of rotation of the medium die, the presence / absence of a release agent added to the medium die, and the softness of the material kneading, and the case of using each medium die The molding results of are shown in Table 1.

In Table 1, the hardness of the material "soft" indicates the degree to which the wrinkles of the soil disappear when the soil is gripped with the hand, and "hard" the extent to which the wrinkles of the soil occur when the soil is gripped with the hand. Shows the hardness of.

As is apparent from Table 1, in Examples 1 to 9 of the present invention, molding and mold release were possible, and the molded body was not deformed or was slightly deformed even if deformed.
On the other hand, in Comparative Examples 1 to 6, molding results were obtained such that the middle mold did not come off and cracks occurred in the molded product.

Furthermore, it is shown in FIGS. 5, 6 and 7 how the product according to the present invention is excellent in moldability and releasability.
This will be described in comparison with the comparative example shown in the figure.

The comparative example 10 shown in FIG. 5 has an inner diameter of the outer mold 5 of about 1 m when the mold is released.
The pressurized air is supplied into the cylindrical hole 7 through the hole 5a of m. In this case, the draft S is 0.25 / 8 in the cylindrical hole 7.
It is added with a gradient value of 0. According to this comparative example, holes 5
The kneaded material entered the inside of a at the time of molding, and some of the materials could not be released, and more buckling of the molded product occurred.

In Comparative Example 11 shown in FIG. 6, the molded product 3 after molding is vacuum-suctioned, and the molded product 3 is to be released from the upper part as shown by the arrow. In this case, a draft of 0.25 / 80 is added to the cylindrical hole 7. In the case of this comparative example, even if the degree of vacuum was 760 mmHg, the molded body could not be released, and buckling occurred in the outer mold 5. Further, after 3 minutes of drying with a dryer, the degree of vacuum was set to 760 mmHg, but the mold release was impossible.

In Comparative Example 12 shown in FIG. 7, the middle mold 2 is slightly eccentric with respect to the outer mold 5 and press-molded to improve the releasability. According to this comparative example, as compared with the conventional example with no eccentricity shown in FIG. 3, the adhesion occurrence rate of the molded product to the outer peripheral surface of the middle mold 2 was considerably reduced, but the core deviation and uneven thickness of the molded product occurred. However, the dimensional accuracy deteriorated.

Further, in Comparative Example 13 (not shown), various comparative tests were conducted by changing the type and amount of the releasing agent, but it was found that the releasing effect does not change significantly depending on the type of releasing oil. Also, if the amount of release oil applied is small, the releasability deteriorates,
Adhesion of the molded product occurred to either the middle mold or the outer mold.
From this, it was confirmed that the release effect is improved by applying the release agent to the middle mold or the outer mold. However, it was not possible to effectively improve the releasability only by applying the release agent.

(Effects of the Invention) As described above, according to the method for pressure-molding a bottomed cylindrical kneaded product of the present invention, the middle mold is rotated to perform pressure-molding, and at the same time, the air vent recess is formed at the time of pressure-molding. As a result, the molded bottomed cylindrical product can be reliably released from the mold, and the deformation of the molded product obtained by the pressure molding is very small and the dimensional accuracy is high.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a pressure molding apparatus according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing an example and a comparative example of a medium-sized transverse cross-sectional shape, and FIG. 3 is a conventional pressure molding apparatus. FIG. 4 is a sectional view of a pressure molding apparatus for explaining the problems of the conventional example, and FIGS. 5, 6, and 7 are sectional views showing a pressure molding apparatus of a comparative example. Is. 5 ... Outer mold, 6 ... Medium size, 7 ... Cylindrical hole, 9 ... Equilateral surface (recess for air release).

Claims (1)

[Claims] 1. An outer mold having a cylindrical hole with a bottom inside, a rotating body insertable into the cylindrical hole, wherein the rotating body has an equilateral surface and an arc surface formed on an outer peripheral surface of the rotating body, or And a middle die having a curved surface whose outer diameter is gradually reduced in the circumferential direction on the outer peripheral surface of the cylindrical body, the middle die is preliminarily rotationally driven, and the middle die is rotated with respect to the kneaded material filled in the bottomed cylindrical hole. While moving forward in the pressing direction, the kneaded product is pressure-molded, and then the middle mold is extracted from the outer mold by returning in the counter-pressing direction while rotating the middle mold from the kneaded product. A method for pressure-molding a bottomed tubular kneaded product.