JPH01176277A - Production of ceramic tubular form - Google Patents

Abstract

PURPOSE:To obtain at low cost the title ceramic tubular form of high precision in high efficiency, by calcination of a tubular form made from ceramic raw powder with a ceramic pin having a specified outer diameter inserted thereinto. CONSTITUTION:Ceramic raw powder such as of alumina or zirconia is spiked with necessary ingredients such as sintering aid and binder followed by forming into a tubular form. On this tubular form 1, a slit 2 in the axis direction is provided. Thence, a ceramic pin P having a specified outer diameter (e.g. made of alumina) is inserted into said tubular form 1 to control and set the inner diameter after calcination. The tubular form 1 with said ceramic pin P kept inserted thereinto is then calcined to effect shrinkage of said form 1, resulting in pressing of the tubular form 1 on the outer periphery of the pin P. After the calcination, the pin P is drawn out, thus obtaining the title ceramic tubular form with precise and dense inner wall surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a ceramic tubular body having a predetermined inner diameter.

[Conventional technology]

Conventionally, when firing a ceramic body, the shrinkage rate due to firing is measured in advance, and in order to create a ceramic body (fired body) that corresponds to the shrinkage rate, press molding with a mold, extrusion molding, or machining is performed. There is. For this reason, when a ceramic material powder is mixed with a sintering aid, a binder, etc. and then fired into a desired shape, the dimensions after firing vary depending on the shrinkage rate, resulting in high accuracy. For example, for ferrules that make up optical fiber connectors, which require dimensions such as ) is currently being carried out.

[Problem that the invention seeks to solve]

As described above, the conventional ceramic body firing method results in variations in the shrinkage rate of the ceramic body itself due to firing. In particular, with a tubular body 10 as shown in FIG.
It has a slit 20 in the axial direction and has an inner diameter of 3.
Cylindrical ceramic bodies with a narrow diameter of 0 ms or less have large variations in internal diameter, so precision machining must be performed after firing, and the time required for the machining is enormous, increasing processing costs and reducing the quality of the product. The price was high.

[Means for solving problems]

In order to eliminate the inconveniences associated with firing ceramic bodies as described above, when manufacturing a ceramic tubular body, first, a ceramic raw material powder is formed into a desired tube shape, and a ceramic pin having a predetermined outer diameter is placed in the tubular formed body. A ceramic tubular body with a highly accurate inner diameter is manufactured by firing the ceramic tube with the tube inserted through it.

〔Example〕

Examples of the present invention will be specifically described below.

Now, when manufacturing the ceramic tubular body 10 as shown in FIG. 1, if the ceramic tubular body 10 is made of alumina ceramic or zirconia ceramic, alumina (AIto3) or zirconia (ZrO □) Mix sintering aids, binders, solvents, etc. with the sized raw powder of It is formed to a size that takes into account in advance that the inner diameter size of the molded material will be approximately 20% smaller than the original molded size.

Next, an axial slit (or groove may be used) 2 is made in the unfired tubular body 1 formed into a tubular shape. The slits 2 may be formed simultaneously with the formation of the tubular body 1, or grooves may be formed only on the outer or inner surface in the axial direction of the cylinder.

Next, fine ceramic powder and dust adhering to the inner wall surface of the tubular body 1 having the slits 2 formed therein are removed by blowing compressed air or the like.

Next, alumina is used to control and set the inner diameter dimension after firing.
A ceramic pin P made of ceramic such as silicon carbide or silicon nitride is inserted into the tubular body 1 as shown in FIG. The ceramic pin P is dimensioned so that the entire inner wall surface of the ceramic pin P comes into contact with the outer circumferential surface of the ceramic pin P. Also, the ceramic pin P has a small thermal expansion coefficient (sufficient enough to be used repeatedly for firing the tubular body 1). It is preferable to use alumina ceramics, which have heat resistance and do not react with the material of the tubular body 1 to be fired during firing or cause changes in the composition structure.

When the tubular body 1 is fired in a temperature atmosphere suitable for the ceramic material forming the tubular body 1 with the ceramic pin P inserted therethrough, the tubular body 1 contracts and the ceramic pin P is fired.
Press the outer circumferential surface of the In other words, the tubular body 1 is regulated by the ceramic bottle P when fired. After firing,
By removing the ceramic pin P, a ceramic tubular body having a precise inner wall surface defined by the thickness of the ceramic pin P is manufactured. In order to efficiently fire a large number of tubular bodies 1, a relatively long ceramic pin P may be used, and the firing may be performed with the plurality of tubular bodies 1 inserted through the pin P.

(Example) Dimensions after firing: outer diameter 3.8 ± 0.05 mm, inner diameter 2.3
A tubular body 1 selected to produce a ceramic tubular body of 5±0.05+m- is made mainly of zirconia (ZrOt) with an appropriate amount of YtOs added as a sintering aid, and kneaded with a binder, an organic solvent, etc. was formed into a long tubular shape by an extrusion method, and cut into a length that would have a length of 12 m5 after firing. Next, a slit 2 with a width of 0.7 mm was made at one location in the axial direction by cutting. After that, compressed air is sprayed onto the inner wall surface of the tubular body 1 to perform a cleaning operation to remove deposits.

Next, as shown in FIG.
It was fired for 4 hours in an oxidizing atmosphere at 1400° C. with a ceramic pin P made of alumina ceramic having a length of 13 mm and a straightness of 0.5 μm being inserted.

After firing, the state was as shown in FIG. 4, and by removing the ceramic pin P, a ceramic tubular body similar to the tubular body 10 shown in FIG. 1 was obtained. The ceramic pin P used at that time had its outer surface polished to a mirror finish better than 0.8 μm Rwax. The inner diameter dimension, inner diameter roundness, and inner surface straightness of the ceramic tubular body manufactured in this way were measured. The measured average value and the measured value of the product manufactured by the conventional honing method are shown in Table 1 as a comparative example.As can be seen from Table 1, the manufacturing method according to the present invention also
Although the slits 2 were formed by cutting before firing, no decrease in accuracy was observed in the products in which grooves were cut on the inner wall surface or outer surface during molding and firing as shown in Table 1.

〔Effect of the invention〕

As mentioned above, according to the manufacturing method of the present invention in which firing is performed with a ceramic bottle having a predetermined dimensional accuracy inserted, the inner diameter dimension of the tubular body to be manufactured can be easily controlled during firing. Moreover, the inner diameter processing after firing can be omitted. Ceramic bottles are also reusable and can be used more than 10 times without applying significant stress.

As described above, according to the present invention, a highly accurate ceramic tubular body can be provided with high production efficiency and at low cost (inner diameter machining cost is one-tenth or less of that of conventional honing).

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a ceramic tubular body, FIG. 2 is a diagram illustrating the order of processing steps in the method for manufacturing a ceramic tubular body according to the present invention, and FIGS. 3 and 4 are both for manufacturing a ceramic tubular body according to the present invention. It is a perspective view explaining the process of a method. 1: Tubular body 2 Nisrit P: Ceramic bottle

Claims (1)

[Claims] 1. A method for manufacturing a ceramic tubular body, which comprises forming a ceramic raw material powder into a tubular shape, and firing the shaped body with a ceramic pin having a predetermined outer diameter inserted therein.