JPH04357120A - Use of jig and tool for molding glass - Google Patents

Abstract

PURPOSE:To prevent chipping (powdering) of boron nitride (BN) powder in using a jig and a tool for molding glass by containing a molded article of BN. CONSTITUTION:A jig and a tool for molding glass, containing >=10wt.% BN are made by molding and after molding, the jig and the tool for molding glass are subjected to ultrasonic cleaning. Since BN powder insufficiently bonded during molding is removed, powdering in use after that is eliminated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of using a glass forming tool containing boron nitride.

0002

[Prior art] Molded bodies of BN (boron nitride)
As described in Publication No. 1-317, it is an excellent heat-resistant material that can withstand temperatures of 2,000°C or higher in an inert atmosphere, and also exhibits excellent lubricity and mold release properties, so it can be used as a mold for molding glass optical elements. Or some of them have excellent properties as glass forming jigs and tools such as crucibles for storing molten glass, knives for cutting molten glass, and conveying jigs.

However, the BN molded body has a problem that it cannot be used in areas where a relatively large load is applied because its mechanical strength is extremely low. Therefore, as a glass molding jig, it is necessary to increase the mechanical strength while maintaining the excellent lubricity and mold releasability of BN, and molded bodies mixed with Al2O3, ZrO2, etc. are suitable.

[0004] In addition, in such a mixed molded product, B
It has been experimentally found that unless N is contained at 10% by weight or more, it is not suitable as a glass forming jig having the characteristics of BN.

[0005]

[Problems to be Solved by the Invention] However, when a molded product containing 10% by weight or more of BN is used as a jig for various glass moldings as described above, a powder blowing phenomenon occurs in which the white powder of BN peels off during use. is occurring. This powder blowing causes the BN powder to adhere to the glass as a workpiece, resulting in surface defects.

Accordingly, an object of the present invention is to provide a method of using a glass forming jig that can handle glass while suppressing such powder blowing.

[0007]

[Means for Solving the Problems] In the present invention, a glass forming jig containing 10% by weight or more of boron nitride and formed into a predetermined shape is used after being ultrasonically cleaned in a liquid.

[0008]

[Effect] Powdering occurs when a molded product containing BN is molded, and the BN powder is not bonded with sufficient force, or the BN powder has weakened bonding strength due to impact during processing into the desired shape. However, this is because it peels off due to force, vibration, etc. applied when used as a glass molding jig.

[0009] In the above structure, since the glass molding tool is ultrasonically cleaned in liquid in advance, BN powder with insufficient bonding strength can be removed before use, and the phenomenon of powder blowing during use can be suppressed. can do.

0010

[Example 1] 70% by weight of Al2O3 powder, 3% of BN powder
After pre-pressing at a pressure of 1.2 tons, the mixture was pre-fired at a temperature of 1000° C. for 8 hours, and then ground to obtain a pre-molded body with dimensions similar to the desired base material. The pre-molded body was main fired at a temperature of 1500° C. for 80 hours to obtain a BN-containing shaped body. Thereafter, further grinding and polishing were performed to form a desired shape as a mold for molding an optical element. After this mold was ultrasonically cleaned in water for 10 hours, the LaK glass was melted at 1450°C, and the mold temperature was 8
When molded at 00°C, no defects were observed in the molded product even after 3000 shots of continuous molding. On the other hand, when the mold was used for similar molding without ultrasonic cleaning, BN powder often adhered to the surface of the optical element, and the defect rate was 46%. .

[0011]

[Example 2] ZrO2 powder 90% by weight, BN powder 10% by weight
A molded article was prepared in the same manner as in Example 1 using a mixing ratio of % by weight. In this example, this molded body was used as a cutting tool for cutting molten glass. After processing this knife into the desired shape,
When the glass was ultrasonically cleaned in oil for 5 hours and used for cutting, there was no fusion of the glass even after 1,000 uses, and the cut glass had defects due to powder blowing only three times. On the other hand, when the glass was used for cutting without ultrasonic cleaning, there was no glass melting after 1000 uses, but defects due to powder blowing occurred 620 times.

0012

[Effects of the Invention] Since the present invention uses the glass molding tool after ultrasonically cleaning it in liquid, powder blowing can be suppressed.
Glass defects due to powder adhesion are no longer caused.

Claims (1)

[Claims] Claim 1: Contains 10% by weight or more of boron nitride,
1. A method of using a glass molding tool, which comprises using the glass molding tool molded into a predetermined shape after ultrasonically cleaning the glass molding tool in a liquid.