RU2554969C1 - Apparatus for moulding glass hemispheres - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: apparatus for moulding glass hemispheres comprises a heating chamber, a hearth with counterweights, which is composite and consists of a central part connected to a rod and a peripheral part with position fixing members, a mechanism for raising and lowering the hearth using the rod connected thereto and a vacuum system. In the heating chamber on the peripheral part of the composite hearth there is a heat shield in the form of a truncated cone with a toroidal cover placed on top of the truncated cone, wherein the truncated cone and the toroidal cover are made of quartz ceramic containing not less than 99.9% SiO₂.

EFFECT: low power consumption and shorter duration of the moulding process.

2 dwg

Description

The invention relates to the building materials industry, in particular to the field of production of bent products with parabolic or spherical curvature of the surface, used, for example, as reflectors for aerodrome light-signal approach lights.

Devices, furnaces, or horizontal installations of circular cross-section are usually used to bend such products, since this creates the most favorable conditions for uniform heating and cooling of both the bending form and the glass billet to be baked.

A device for glass molding is known, comprising a furnace mounted with the possibility of vertical movement of its arch and side parts relative to the shape of the molding located on the stationary hearth of the furnace according to ed. testimonial. SU No. 511300, C03B 23/02, publ. 04/25/1976

A disadvantage of the known device is that after heating the furnace and the bending form located in it to the glass softening temperature, its arch and side parts are raised to their highest position to place a round flat glass workpiece on a heated form that is outside the space of the furnace. During this period of time, a large heat loss occurs both in the working space of the furnace and from the bending form. In addition, in the process of bending glass workpieces with a parabolic or spherical curvature of the surface, it almost always becomes necessary to correct (eliminate the skew) the position of the glass work pieces relative to the molding surface of the bending. In this case, it is necessary to raise the arch and side parts of the furnace again to their highest position. The above factors lead to high energy costs and increase the time of the bending process.

A known installation for molding glass hemispheres, containing a heating chamber, vertically moving below with counterweights, a mechanism for raising and lowering the hearth by means of a rod connected to it and a vacuum system connected to the heating chamber by means of a flexible sleeve (Zheludkov D.D. Installation of molding of glass hemispheres. Information sheet VIMI No. 86-2144, published in 1986).

Closest to the invention is a glass hemisphere bending apparatus, comprising a heating chamber, vertically moving below with counterweights, made integral, consisting of a central part connected to the rod and an edge part with latches for its position, a mechanism for raising and lowering the hearth by means of a rod connected to it and the vacuum system according to patent RU No. 2498948, IPC C03B 23/02, publ. November 20, 2013

A disadvantage of the known installation is that after heating the chamber and the bending mold located on its bottom to the softening temperature, the glass is lowered to its lowest position in order to place the glass blank on the mold, which, together with the hearth, is outside the space of the heating chamber. During this period of time, a large heat loss occurs both in the working space of the chamber and from the hearth with the mold. In practice, in the process of bending glass workpieces with parabolic or spherical curvature, it is necessary to correct (eliminate skew) the position of the glass workpieces relative to the forming surface of the mold one or more times. In this case, it is necessary to lower the under again with the form located on it to its lowest position. All of the above factors lead to high energy costs and increase the time of the bending process.

The objective of the invention is to reduce energy consumption and time of the process of bending glass.

This task is achieved by the fact that the proposed installation of molding glass hemispheres from flat glass blanks, containing a heating chamber, under counterweights, made integral, consisting of a central part connected to the rod, and an edge part with latches of its position, a mechanism for raising and lowering the hearth by means of a connected with it a rod and a vacuum system, characterized in that on the edge of the composite hearth there is a heat shield made in the form of a truncated cone with a toroidal cover located on the upper part of the truncated cone, while the truncated cone with a cover made of quartz ceramics containing at least 99.9% SiO ₂ .

The installation of a heat shield made in the form of a truncated cone with a toroidal lid located on the upper part of the truncated cone provides an increase in the heat capacity of the space inside the truncated cone compared to the prototype in the process of lowering the central part of the composite hearth to the lower position and placing a flat glass blank on the bending shape. After raising the central part of the hearth to the upper position, the space inside the truncated cone, where the bending form is located with the flat glass blank placed on it, is thermostabilized faster compared to the prototype. In this case, the glass-cutting edge region is shielded from direct beam heating of the arch heaters of the heating chamber with the help of a toroidal shape lid. Thus, the bending of the edge region of the flat glass is slowed down in comparison with its central part. This circumstance provides a symmetrical bending of the glass blank without adjusting it in shape during the bending process. The proposed installation provides a significant reduction in energy consumption and time during the bending process in comparison with the prototype.

The implementation of a truncated cone with a toroidal lid made of quartz ceramics containing at least 99.9% SiO ₂ provides a very long service life at a milling temperature (600-650) ° C, since the thermal expansion coefficient of the specified quartz ceramics from room temperature to temperature bending is practically zero. Therefore, the temperature difference that occurs when the central part of the hearth is lowered to the lower position for loading flat and unloading bent glass blanks does not significantly affect the life of the truncated cone with a toroidal shape.

FIG. 1 - Installation when the central part of the hearth is closed.

FIG. 2 - Installation in the open position of the central part of the hearth.

The installation contains a heating chamber 1 and a composite under, consisting of a central part 2 connected to the rod 3, and an edge part 4 with latches 5. The heating chamber 1 and a composite under are mounted on a metal frame 6 with a mechanism 7 and balances 8 for moving the rod 3 along vertical from the extreme upper position of the center part 2 of the hearth (Fig. 1) to the extreme lower position of the central part 2 of the hearth (Fig. 2). On the central part 2 of the hearth there is a molding form 9, the working space of which is connected to the vacuum system 10 by means of a metal tube 11 located on the rod 3.

A heat shield is installed on the edge part 4 of the composite hearth, made in the form of a truncated cone 12 with a toroidal cover 13 located on the upper part of the truncated cone 12. The truncated cone 12 and the cover 13 are made of quartz ceramic containing at least 99.9% SiO ₂ .

Installation works as follows.

After heating the chamber 1 (Fig. 1) to a glass softening temperature and holding for 30–40 min, the central part 2 of the hearth is lowered to the lowermost position (Fig. 2) using the mechanism 7 and counterweights 8. The edge part 4 of the hearth is fixed relative to the frame 6 with the help of clamps 5. Next, a round flat glass blank 12 is placed on the mold 9 (Fig. 2) and the central part 2 of the hearth is lifted to its highest position (Fig. 1) using the mechanism 7 and the weights 8. In connection with the increase the heat capacity of the space of the heating furnace, where put the form of bending 9, due to the placement of the heat shield, made in the form of a truncated cone 13 with a cover 14, the time to reach the softening temperature of the glass workpiece 12 is significantly reduced in comparison with the prototype. In addition, due to the slowing down of heating of the flat billet in its edge region compared to the central one due to the shielding of radiation heating by the toroidal cover 14, the maximum bending under the action of its own weight occurs in the central part of the glass workpiece 12 (Fig. 1), position II.

This circumstance provides a symmetrical bending of the glass workpiece 12 (Fig. 1) position III after suction of air from the space between the glass workpiece 12 and the forming surface of the mold 9 using the vacuum system 10 and the metal tube 11. After the milling process is completed, the vacuum system 10 and the heating of the chamber 1 are turned off.

Example. Glass blanks designed to produce reflectors used in approaching aerodrome light-signaling lights must be molded. In this case, a mold with a diameter in its upper part of 210 mm is used. The installation has the following parameters: the diameter of the working space of the chamber 1 is 650 mm, the height is 400 mm, the diameter of the central part 2 of the composite hearth is 260 mm, the diameter of the truncated cone in its lower part is 280 mm, in its upper part is 220 mm, the diameter of the toroidal lids for large diameter - 240 mm, for small diameter - 200 mm.

A batch of the above bent glass blanks was obtained. At the same time, energy costs amounted to 70%, and the time of the process of bending 75% in comparison with the prototype.

Information sources

1. Auth. testimonial. SU No. 511300, IPC C03B 23/02, publ. 04/25/1976

2. Zhuludkov D.D. Glass hemisphere bending installation. Information leaflet VIMI 386-2114, publ. 1986 year

3. Patent RU No. 2498948, IPC C03B 23/02, publ. November 20, 2013

Claims (1)

Installation for bending glass hemispheres from flat glass blanks, containing a heating chamber, under with balances, made integral, consisting of a central part connected to the rod and an edge part with latches for its position, a mechanism for raising and lowering the hearth by means of a connected rod and a vacuum system, characterized in that on the edge of the composite hearth there is a heat shield made in the form of a truncated cone with a toroidal shape located on the upper part of the truncated cone, a truncated cone with a cover made of quartz ceramic containing at least 99.9% SiO ₂ .

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