SU1689310A2 - Mould for making telescope mirror - Google Patents

Abstract

The invention relates to the construction industry, to devices for pouring and subsequent heat treatment of large billets from glass ceramics, in particular, for a telescope mirror. In order to improve the quality of the mirror blank by ensuring uniform spreading of the glass mass from the center to the edges of the blank and eliminating the glass blinking, the platinum foil is made with protrusions around the perimeter, pressed against the shell lining. The central part of the foil with a size of at least 0.08-0.25 diameter of the mold is provided with an additional platinum screen, hermetically welded with the foil to form a continuous air insulating layer between the foil and the screen. 2 Il.

Description

WITH

with

The invention relates to the construction industry, to devices for pouring and subsequent heat treatment of large billets from glass ceramics, in particular for a telescope mirror, and is an improvement of the basic invention according to the authors St. Nfe 804580.

The purpose of the invention is to improve the quality of the mirror blank by ensuring uniform spreading of the glass mass from the center to the edges of the blank and eliminating the glass bubbling.

FIG. 1 shows the proposed form, a longitudinal section; in fig. 2 - foil, top view.

The mold for casting the telescope mirror billet mirror consists of a cylindrical shell 1, a pallet containing the upper split steel sheets 2 and the lower cast iron solid sheets 3, and a thin

refractory lining 4 with a polished top surface. The collecting tray is made, for example, of two cast-iron disks 85 and 110 mm thick and two split steel disks (steel H18H10T) 50 mm thick in the form of 12 sectors with a central disk 5. The shell of the form is lined with a lightweight chamotte 6 with a thickness of 150 mm. The refractory lining of the pallet must conduct heat well, therefore the thickness. should be small - on the order of 20-30 mm. So, when casting billets of small diameter (1-3 m, 2-3 m), highly heat-conducting silicate in the form of polished tiles with a thickness of 30 mm was selected as the lining of the pallet. In molds designed for casting large pieces (3-6 m), the central part of the lining is made of refractory material with low thermal conductivity, for example, of alumina refractory. Refractory lining

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4 (siliconized graphite) is covered with high-alumina tile 7 of the mark MKO-72 with a thickness of 30 mm and platinum foil 8 of the proposed design. There is also an additional platinum screen 9. Along the perimeter of the foil, the protrusions 10 are made. Screen 9 is hermetically welded with the foil to form a continuous air insulating layer 11 between the foil and the screen.

The form is used as follows.

The platinum foil of the proposed design is placed on the bottom of the mold and pressed against the shell lining. For casting, the mold is installed under the casting tube of a glass melting furnace so that the tube is located along the mold axis at a small height from the pallet (50-100 mm). During the pouring out of the glass mass, it spreads evenly over the entire bottom surface of the mold, which, as it is filled, is gradually lowered with the help of a special trolley, keeping the distance from the pipe to the glass mass level in the mold. At the end of the casting, the mold is closed with a lid and poured into the heat treatment furnace. Low tide and

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The subsequent heat treatment in the proposed form for the manufacture of the telescope mirror is carried out aneloachically to the ebb and heat treatment in the form according to the basic auto.

St. N 804580, while ensuring the achievement of the above advantages,

Example. Platinum foil thickness 0.3 mm; diameter of a foil is 6100 mm; quantity

protrusions 24 shg .; projection size 70x20 mm; foil area of 30 m2; the area of the additional screen with a diameter of 500 mm is about 0.2 m2; total mass of foil, protrusions and additional screen 200 kg,

Claims (1)

Invention Formula A mold for making a telescope mirror from a sitall along an ang, st. M 804580, which is due to the fact that, in order to improve the quality of the zerkat's billet, it ensured the uniform spreading of the glass mass from the center to the cracks of the billet and eliminated the glass blistering 5 hermetically welded with platinum foil, made with protrusions along the perimeter, pressed by the shell lining. 2