JPS62292655A - Method for marking glass product - Google Patents

Abstract

PURPOSE:To stamp necessary information which is minute, forms striking contrast, and is hardly effaced even by the subsequent thermal load by partially irradiating the surface of glass set in a reducing atmosphere by laser. CONSTITUTION:At least the part of glass parts to be stamped is set in a reducing atmosphere and preferably preheated to prevent the formation of fine cracks and residual strain. The desired part is then irradiated by laser. Economical CO2 laser, etc., having a wavelength which is not transmitted through glass is appropriately used as the laser. Consequently, the metal oxide such as lead oxide contained in the glass parts is reduced, and a colored metallic thin film is formed on the glass parts as a stamp. Consequently, a mark forming striking contrast, easy to read, and hardly effaceable even by the thermal load after formation can be stamped.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention is directed to the use of glass products such as plate glass, glass containers, and glass parts for electron tubes, such as letters, symbols, and figures. This invention relates to a method for marking necessary information on glass parts.

(Prior art) In addition to printing methods and etching methods, there are also known marking methods for glass products, such as a molding method in which glass softened by heating is marked with a mold. A common method for marking is the synthetic method. However, recently, marking methods using lasers have also been attempted. Specifically, there are methods for directly heating and softening the glass surface with a CO□ laser with a wavelength of 10.6μ that does not pass through the glass, and marking methods that make markings on the glass surface. YAG on the metal film
An example of this method is to partially remove the material by irradiating it with a laser to form a desired marking.

When this method is applied to the stem, which is an internal part of the electron tube, a part of the black film previously formed on the glass part is removed by YAG laser irradiation to form a stamp. Lead oxide is usually present in this glass portion, and a black film is formed by reducing this.

(Problems to be Solved by the Invention) Application of the above-mentioned molding method does not pose much of a problem for products with relatively large areas that can be marked, such as bottles and tableware. Naturally, for products with small molded parts, the area that can be stamped becomes narrower, and the stamp obtained by the molding method also has unevenness, so it is necessary to select a position that does not impair product durability. be. Therefore, it is strange to display a large number of characters, symbols, or figures, and it is only possible to engrave the manufacturing machine number.Furthermore, in the case of electron tube stems that undergo a heat sealing process with other parts during the assembly process, this engraving is It may deform under load and become unreadable.

On the other hand, as mentioned above, any method of marking glass using a laser inevitably generates residual strain and microcracks, which are extremely undesirable problems for electron tube stems used as internal parts of electron tubes.

Furthermore, the markings formed on the lead glass stem by irradiation with the YAG laser do not become transparent and become milky white and satin-like, and scale-like cracks are formed around the markings, which is extremely inconvenient for pipe internal parts.

The present invention provides a new method for marking glass products that overcomes the above-mentioned difficulties, and enables particularly fine markings.

[Structure of the invention]

(Means for Solving the Problems) The present invention employs a method in which a glass product is irradiated with a laser without passing through the glass. In other words, a colored metal coating formed by reducing the metal oxide contained in the glass part is used as a stamp, and the formation of this film prevents the formation of microcracks and residual strain on the glass part around the stamp. Therefore, it is preferable to preheat the laser.As mentioned above, the laser to be used is preferably a C02 laser, which is opaque to glass and is economical, as it enables the formation of minute markings.

(Function) After placing the entire glass product or the part to be engraved in a reducing atmosphere, it is preferable to perform a preheating process to prevent the occurrence of surface cracks. Select a temperature at which a colored metal film will not form on this surface.
% lead glass is kept at 400° C. or lower for less than 3 minutes, and as a result, a human-order colored metal is formed on the surface of this lead glass, but it does not interfere with the engraving process described later.

Next, a metal thin film is obtained as a result of a reduction reaction that occurs by irradiating and heating the position where the marking is to be formed on the glass product with a laser beam, and the marking is formed by the locally colored metal thin film. In this way, the colored metal thin film obtained by laser light can be formed with fine characters, symbols, and figures, so necessary information such as the date of manufacture, lot number, and product name can be engraved. As this laser, an infrared laser with a wavelength of 4.8 .mu.m or more that does not pass through glass can be used, and considering economic efficiency, a 002 laser with a wavelength of 10.6 .mu.m is practical.

(Example) The present invention will be explained in detail with reference to FIGS. 1 to 5.

FIG. 1 is a sectional view schematically showing a stem for an electron tube according to the present invention, FIGS. 2 a, b, and c are sectional views and perspective views of this stem component, and FIG. FIG. 4 is a sectional view schematically showing the equipment to which the present invention is applied, and FIGS. 4a and 4b are sectional views showing other embodiments. By the way, the electron tube stem 1 is a glass tube 2. The Dumet wire 3... and the glass ring 4 are heated and formed into one body in a press molding process.
The cross-sectional structure shown in the figure is obtained, and the Dumet wire 3 oxidized by this forming process is reduced by the reducing flame of the hydrogen cap 5 shown in FIG. 3 in order to improve weldability with the electron gun.

Prior to this reduction reaction using hydrogen, the above-mentioned preheating step is performed. Glass tube 2 and glass tube 4 contain 30% by weight of lead oxide.
The electron tube stem made of this material is kept at a temperature of 400° C. for 3 minutes to soften it somewhat, and then moves to the reduction step.

In the reduction step using the hydrogen cap 5 described above, the entire electron tube stem is covered with the flame, and the mark 6 is formed by irradiating the marking formation position of the stem with CO and laser having a wavelength of 10.6 μm. This marking 6 consists of a colored metal thin film formed by the reduction of lead oxide in a reducing atmosphere and provides the necessary information.

In order to use this laser, it is natural to use the laser beam 8 generated from the laser device @7 shown in Fig. 3, but it is conventionally known to set a plurality of markings 6 for diversification. A common method is to move the laser beam in the X direction and the Y direction by converting the laser beam angle using a mirror.

By scanning this laser beam, the markings can be diversified and the contents can be changed freely. Furthermore, in FIG. 4a, in order to minimize the energy 1oss of the laser beam, the IVA chamber 8 surrounding the electron tube stem is replaced with the laser device 7.
A cross-sectional diagram schematically shows a device that is directly connected to the FIG. 4 shows an example in which a laser beam window 9 is provided in this chamber 8, and this window is made of sapphire, Ca, etc., which transmits the laser beam.
F.

Thallium halide, arsenic-doped cerium glass, etc. are applicable.

〔Effect of the invention〕

According to the present invention, fine cracks and local distortions do not occur, so
It is particularly effective for electron tube stems that require high reliability, and achieving this requires no vapor deposition equipment and can use a laser with comparative paper power, so it is under intense price competition. The resulting markings, which are of great benefit to electronic components, have good contrast and are easy to read because the colored metal thin film formed on the surface of the glass product is applied, and also has the advantage of being easily erased by heat load after forming. Furthermore, since there are almost no irregularities, it is possible to form products without restrictions on product shape or position. Furthermore, necessary information such as manufacturing date, loft number, and manufacturing machine number can be stamped all at once.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an electron tube stem to which the present invention is applied, Fig. 2 a, b, and c are sectional views and perspective views of parts necessary therefor, and Fig. 3 is a schematic diagram of a device necessary for the present invention. 4a and 4b are cross-sectional views showing another device to which the present invention is applicable.

Claims (1)

[Claims] A method for marking glass products, which is characterized in that necessary information is engraved with a metal thin film formed by partially irradiating the surface of glass installed in a reducing atmosphere with a laser.