KR100258492B1 - Method of manufacturing ceramic and porous mold used therefor - Google Patents

Abstract

A mold surface of a shape corresponding to the shape of the suspension insulator and other similar ceramics, which is formed as a center portion of the mold and the outer periphery of the mold, and has a small diameter hollow tube center core portion having a sealed head portion and a large diameter shed portion extending radially from the core portion. A porous molding mold for producing a ceramic having a porous molded body having a body, wherein the water absorption of the mold surface side portion of the mold outer periphery is greater than that of the mold center portion. The water absorption of the mold surface portion of the mold peripheral portion is 20-30%, and the water absorption of the mold head portion of the mold central portion is 10-20%. The difference in water absorption between the mold surface side and the mold head of the outer periphery of the mold is 5-20%.

Description

Ceramic Manufacturing Method and Porous Molding Types Used in the Same

1 is a cross-sectional view showing an embodiment of the porous gypsum molding of the present invention.

2 is a front view of a perforated tube held by a wirework core.

3 is a cross-sectional view showing a porous gypsum manufacturing method according to the present invention.

Figure 4 is a front view showing in half a section an embodiment of the ceramic produced by the present invention.

FIG. 5 is an explanatory diagram of problems such as deformation caused when the suspension insulator shown in FIG. 4 is manufactured using a conventional porous molding die. FIG.

* Explanation of symbols for main parts of the drawings

1: mold 2: porous gypsum molding body

4: perforated tube 5: wire walk

3, 6: mold surface 7: flat surface side portion

8: center part 8a: head part

12: inner mold 15: sealed head

16: small diameter central park tong central core part 17: large diameter shed part

The present invention relates to a ceramic manufacturing method, in particular to the manufacture of suspension insulators and other similar ceramics having a small diameter hollow tube center core portion having a closed head portion and a large diameter shed portion extending radially from the central core portion. It is about a method.

Until now, the suspension insulator etc. which have the center diameter part of a small diameter hollow tube, and the large diameter shed part have been manufactured using the porous shaping | molding die. The porous molding die includes a central portion and a peripheral portion, and has a mold surface having a shape surface corresponding to the shape of the ceramic to be molded, that is, the center core portion of the suspension insulator and the shed portion, and is embedded in the porous molding body along the mold surface. A porous tube is provided.

In a conventional method of manufacturing a suspension insulator or the like, a batch is pressed and adhered to the mold surface by applying negative pressure to the entire mold surface through a porous tube to form a molded article of a precise shape. After molding, the compressed air is blown from the mold surface to release the molded article from the mold surface, and the molded article is taken out of the porous molded mold.

However, in the conventional method described above, the mold cracks generated by the molding load caused by the decrease in strength of the porous molding having high porosity, the excessive air blow acting on the molded article when the molded article is released from the porous molding. (blow) Deformation of the molded part due to the pressure, impossible release due to poor air blow pressure, breakage of the molded part at the boundary between the small diameter central core part and the large diameter shed part, deformation due to the rise of the head part of the molded part, etc. .

It is an object of the present invention to provide a method for improving suspension insulators and other ceramics for solving the above problems.

Another object of the present invention is to provide a porous molding die used for carrying out the process according to the invention.

According to one aspect of the present invention, there is provided a suspension insulator and other similar ceramic manufacturing method having a head-tight small diameter hollow park barrel central core portion and a large diameter shed portion extending radially from the core portion, the mold center portion and the outer peripheral portion, Pressing the batch on the mold surface of the porous mold having a mold surface corresponding to the outer shape of the core portion and the large diameter shed portion to form the molded article, and then blowing the gas from the mold surface to release the molded article from the mold surface. The molded article is removed from the mold, and a porous mold is used in which the water absorption of the mold surface side of the outer periphery of the mold is higher than that of the center of the mold.

According to the second aspect of the present invention, the porous molded mold includes a mold center portion and an outer mold peripheral portion and a suspension insulator and other similar ceramics having a head-closed small diameter hollow park central core portion and a large diameter shed portion extending radially from the core portion. And a porous molded body having a mold surface of a shape corresponding to the external shape of the mold, wherein the water absorption of the mold surface side portion of the mold outer periphery is greater than that of the mold center portion.

According to the present invention, the water absorption of the mold surface side portion of the outer mold peripheral portion is preferably 20-30%, and the water absorption of the closed head portion of the mold center portion is preferably 10-20%.

Moreover, according to this invention, it is preferable to make difference A-B between the water absorption rate (A) of the mold surface side part of the said outer periphery part, and the water absorption rate (B) of the sealing head part of the said mold center part to 5-20%.

In addition, according to the present invention, the porous molded main body including the mold center portion and the outer peripheral portion of the porous mold can be formed of a porous body such as gypsum, synthetic resin, porous ceramics, sintered metal and mixtures thereof, It is preferably used because it is a cheap material and easy to recover.

As the synthetic resin material, epoxy, urethane, phenol, acrylic, silicone are used, and as ceramic material, mullite, cordierite, alumina, zircon and glass are used, and as sintered metal material, iron, etc., Nickel, stainless steel, aluminum and brass are used.

Further, according to the present invention, the means for controlling the water absorption rate between the head portion of the mold center portion of the porous mold and the mold surface side portion of the outer periphery of the mold is preferably capable of locally changing the porosity of the porous mold. .

Further, according to the present invention, the means for controlling the water absorption rate between the head portion and the mold surface side portion of the porous mold is preferably capable of arranging the porous tube only along the mold surface of the outer periphery of the mold.

According to the present invention, as described above, a large amount of gas is released at the time of releasing the mold body by using a porous molding die having a water absorption rate of the mold surface side portion of the mold outer peripheral portion higher than that of the head portion of the mold center portion. The shed portion is released prior to the central core portion by being blown to the larger diameter shed portion than the core portion and as a result the molded article can be easily taken out of the mold without any deformation or damage.

Other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

4 shows one embodiment of the ceramic produced by the method of the present invention, one embodiment of which is shown from a small diameter hollow tube center core portion 16 and a central core portion 16 having a sealing head portion 15. FIG. A typical suspension insulator with a large diameter shed portion 17 extending radially is shown.

In the case of manufacturing the above-described suspension insulator shown in FIG. 4, the batch is pressed onto the mold surface of the porous molding die shown in FIG. 1, and a negative pressure is applied to the mold surface to close the batch to the mold surface. After molding, the compressed air is blown from the mold surface to release the molded product from the mold surface and taken out from the mold.

FIG. 1 shows the porous gypsum forming mold used to mold the suspension insulator shown in FIG. 4, which is cast on the inner surface of the mold 1 and the mold 1 made of metal such as aluminum. A porous gypsum-molded body 2. The porous molded body 2 includes a mold surface side portion 7 and a mold center portion 8 of the outer peripheral portion. The mold surface side portion 7 has a mold surface 3 of a shape corresponding to the external shape of the large diameter shed portion 17 and the mold center portion 8 has an outer shape of the small diameter central core portion 16 of the suspension insulator to be molded. It has a mold surface 6 of a corresponding shape.

In the illustrated embodiment, the porous tube 4 is formed only along the mold surface 3 of the mold surface side portion 7 of the mold outer periphery, for example, at about 25 mm away from the mold surface 3. It is embedded in the mold main body 2. The porous tube 4 is preferably a glass fiber tube called, for example, a so-called sizing tube.

The perforated tube 4 is spirally wound on the outside or inside of the wire work 5, which is preferably made of steel wire in the form of a fan guide as shown in FIG. 2 and is provided at the lower end of the mold 1 at the inlet end. It is connected to a vinyl tube 10 extending from a fitting 11.

The fitting 11 is connected to a vacuum source (not shown) when the suspension insulator is molded, thereby applying a negative pressure to the mold surfaces 3 and 6 via the porous tube 4 to allow for placement of the mold surface 3,. In close contact with 6) to form the batch in an elaborate form.

After molding, the fitting 11 is connected to a compressed air source (not shown) to blow compressed air from the mold surfaces 3 and 6 through the porous pipe 4 to release the mold body from the porous molding die. Reference numeral 9 denotes an impermeable gypsum provided at the lower end of the mold 1 to prevent air from blowing outward from the mold center.

In the above-described gypsum molding mold, the porous tube 4 is plastered of the porous molding body 2 only along the mold surface 3 of the outer peripheral portion 7 at a position separated by a distance of 25 mm from the mold surface 3. Is buried in. Therefore, as a result of measuring the water absorption rate, the water absorption rate of 20-30% at the outer periphery of the mold and the water absorption rate of 10-20% at the head portion 8a of the mold central portion 8 are measured. Further, the water absorption rate can be greater at the mold surface side portion of the outer peripheral portion than the mold center portion, and the difference AB between the water absorption rate A of the mold surface side portion 7 and the water absorption rate B of the head portion 8a of the mold center portion 8 Can be 5-20%.

As the porosity of the outer periphery 7 is increased so that the water absorption rate is greater than 30%, as a result, the mold strength of the outer periphery is lowered, which causes cracking in the mold due to the molding load during molding, and blows on release. The amount of blowing-off air is excessively large. Therefore, there is a problem that the molded article is deformed by blow-off air as shown by " a " and " b " in FIG.

Contrary to the above, when the water absorption of the outer periphery of the mold is smaller than 20%, it becomes impossible to release the molded article, and if the molded article is forcibly released, the neck of the molded article as shown by " c " The problem of destruction is caused.

On the other hand, when the water absorption rate of the head portion 8a of the mold center portion 8 is higher than 20%, the amount of blow air is excessively large, and the head portion 15 of the molded article is raised to " d " As shown by the figure, when it is deformed by the blow-off air at the time of release and the water absorption of the head portion is lower than 10%, it becomes impossible to release the molded article.

In addition, if the difference in moisture absorption between the outer peripheral part and the central part of the mold is not 5-20%, the pressure balance at the time of release deteriorates and causes deformation.

Next, the manufacturing method of the above-mentioned porous gypsum molding die is demonstrated with reference to drawings.

First, the porous tube 4, such as a sizing tube made of glass fiber, is spirally wound on the outside or inside of the wirework core 5 made of steel for holding the porous tube in a predetermined shape as shown in FIG. . The porous tube 4 having a shape is set around the inner mold 12 having an outer surface corresponding to the shape of the suspension insulator produced by supporting the wirework core to the spacer 13 so that the porous tube 4 is modified. In order to improve the reliability of the mold under the condition, a mold release agent such as soap water was applied on the outer surface of the mold made of gypsum, and as shown in FIG. 2, the outer surface of the mold 12 by a predetermined interval, for example, 25 mm under an elevated state. Spaced apart from The inner mold 12 and the porous tube 4 are then covered by a mold 1 made of aluminum. The vinyl tube 10 connected to one end of the porous tube 4 is connected to the fitting 11 of the mold 1, and the permeable gypsum, which is degassed under reduced pressure, has a gap 14 between the mold 1 and the mold 12. Air bubbles are slowly injected to prevent them from entering the gypsum. Gypsum 2 fills the gap set by the porous tube 4 upwards and gradually. When the upper surface of the gypsum 2 reaches a predetermined level, the injection of the porous gypsum 2 is stopped and the impermeable gypsum 9 is cast in the space above the porous gypsum 2.

Under this condition, the gypsum is kept at room temperature and begins to cure gradually. When the cast gypsum is semi-cured, the mold 12 is removed and the mold 1 filled with gypsum is inverted so that the mold surface is upward. The mold is installed on the compressed air supply and the fitting 11 is connected to a compressed air supply (not shown) to supply the compressed air to the porous tube 4. Compressed air is 0.5 to 1.0 kg / cm 2 for about 10 minutes, 1.0 to 2.0 kg / cm 2 and 2.5 to 3.0 for about 5 to 10 minutes, for example, by gradually increasing the pressure for about 30 to 40 minutes in total. It is introduced into the porous tube at kg / cm 2. Also, in the later stage of hydrating the gypsum mold, the air flow is adjusted to 4500 l / min, in which the oil clay mass is placed on the mold surface of the central part 8 and pressed by a piston at a pressure of 3 kg / cm 2. The hole on the mold surface 6 is sealed. Thus, the compressed air supplied from the fiber-like porous tube 4 of the sizing tube is dispersed into the semi-cured gypsum through the wall portion of the fiber-like porous tube to remove the portion at the mold surface side of the porous tube 4 of the porous gypsum-molded body. The mold center portion 8 which is mainly flowed toward the mold center portion 8 including the head portion 8a and the mold side portion of the mold peripheral portion by the mold 1 is sealed by the mold 1, but the mold surface of the mold peripheral portion is closed. The mold surface 3 of the side 7 is ejected in the form of a bubble with water on the mold surface 3 which is still kept smooth because it is open.

Water sprayed on the mold surface can be removed by sponge or vacuum suction. As a result, the mold surface side portion 7 of the porous gypsum mold body 2 is formed in a more continuous hole so that the porous mold surface side portion 7 is more than that of the head portion 8a of the mold center portion 8. Has high porosity Compressed air is continuously supplied until the jet of water from the porous gypsum is substantially finished for about 30 to 40 minutes during which the cast gypsum is cured. While the compressed air is supplied, the passage formed by the bubbles blown into the porous gypsum-molded body remains in the form of fine continuous holes when the gypsum is cured to form the porous gypsum-molded body 2 with the continuous holes. have. Next, the porous gypsum forming mold 2 is heated by infrared heating or in a heating oven to be completely cured to produce a porous gypsum forming mold.

The porous molding die of the present invention thus constructed is used as a mold for molding ceramic such as a suspension insulator as in the conventional mold. At the time of molding, the entire molding surfaces 3 and 6 of the porous molding die are depressurized through the porous tube by sucking air through the fitting 11, so that the molded articles adhere to the mold surfaces 3 and 6, so that the molded articles are precisely shaped. Is molded into. In addition, after molding the molded article, air is supplied from the porous tube 4 to the porous molded mold via the fitting 11 to blow air out of the mold surfaces 3 and 6 of the porous molded mold, so that the molded article can be easily 3, 6).

Further, according to the present invention, since air is blown concentrically from the mold surface side portion 7, for example, an amount of air sufficient to release heavy insulators can be blown, and blown from the insulator head portion. The insulator head portion can be prevented from being deformed by adjusting the amount of air to be as low as possible.

As described above, the ceramic manufacturing method according to the present invention and the porous molding used therein can maintain a porosity and a flat surface suitable for manufacturing insulators using extremely cheap gypsum, and the precise molding along the mold is used to reduce pressure and degassing ( deaeration, and easy release can be done by air blow with internal pressure at release. In addition, the porous forming mold can be easily recovered even when a part of the surface is damaged, so that not only the manufacturing cost but also the maintenance cost is low.

Table 1 shows the comparative test results which show the range of the water absorption rate of the porous gypsum molding mold which concerns on this invention.

TABLE 1

In the comparative test of the porous gypsum forming mold according to the present invention, the mold surface side portion and the mold were changed by changing the position of the porous tube, the pressure and time of the compressed air introduced into the porous tube, and the pressure of the oil clay as shown in FIG. Various types of porous gypsum moldings with different combinations of water absorption at the head of the center, using ceramic materials with a composition of 10-35% alumina, 20-35% feldspar and 30-40% clay Many transmission suspension insulators were provided with a central portion 16 having a diameter of 60 mm and a shed portion 17 having a diameter of 254 mm and a height of 100 mm, and their quality was finally evaluated.

The water absorption rate of the mold is determined by cutting the gypsum sample from the mold surface side and the head of each mold to about 15 x 15 x 15 mm, trimming the surface with sand paper, and 40-45 ° C until the sample has a constant weight. The sample is dried for about 24 hours by a hog drier, the sample is cooled to room temperature, the dry weight of the sample is measured, the sample is immersed in room temperature, immediately depressurized and left at 700 mmHg or more for 1 hour, The sample is taken from room temperature water, and the surface is quickly wiped with a damp cloth to remove water droplets, the moisture absorption weight of the sample is obtained, and the moisture absorption rate is determined using the following equation.

In Table 1, the resulting rejection rate is represented by%, and the overall evaluation is represented by very good ○, good Δ, and poor x. As can be seen from Table 1, the mold surface side portion 7 of the mold outer periphery has a water absorption of 20-30%, and the head portion of the mold center has a water absorption of 10-20%. It is possible to manufacture a quality suspension insulator and make the generation of defective products almost zero.

Claims (9)

A ceramic manufacturing method having a small diameter hollow tube core core having a closed head portion and a large diameter shed portion extending radially from the core portion, the ceramic core manufacturing method comprising a mold central portion and a peripheral portion of the outer circumference, the shape corresponding to the outer shape of the central core portion and the large diameter shed portion; Forming a molded article by pressing the batch on the mold surface of the porous molding die having a mold surface, and then blowing gas from the mold surface to release the molded article from the porous molded mold, The water absorption of the mold surface portion is higher than the water absorption of the mold central portion. The method of claim 1, wherein the ceramic is a suspension insulator. The method of claim 1, wherein the water absorption of the mold surface side portion of the mold outer peripheral portion is 20-30%, and the water absorption of the head portion of the mold central portion is 10-20%. The ceramic manufacturing method according to claim 2, wherein a difference in water absorption between the mold surface side portion of the outer mold peripheral portion and the head portion of the mold central portion is 5-20%. A mold surface of a shape corresponding to the shape of a suspension insulator and other similar ceramics manufactured having a small diameter heavy-duty barrel central core portion having a mold center portion and an outer periphery portion and a sealed head portion and a large diameter shed portion extending radially from the core portion A porous molding mold for producing a ceramic having a porous molded body having a body, wherein the water absorption of the mold surface side portion of the mold outer peripheral portion is greater than that of the mold center portion. 6. The porous shaping mold according to claim 5, wherein the water absorption of the mold surface side portion of the mold outer peripheral portion is 20-30%, and the water absorption of the mold head portion of the mold central portion is 10-20%. 7. The porous molding die for ceramic manufacture according to claim 6, wherein the difference in water absorption between the mold surface side portion and the mold head portion is 5-20%. 6. The porous molding mold for ceramic manufacture according to claim 5, wherein the mold center portion and the outer mold peripheral portion of the porous molding mold are formed of gypsum, synthetic resin, porous ceramic, sintered metal or a mixture thereof. 6. The porous shaping mold for producing ceramics according to claim 5, wherein the porous tube is disposed only along the mold surface of the mold surface side portion.