Glass-metal sealing process for vacuum heat collecting tube

Abstract

The glass-metal sealing process for vacuum heat collecting tube includes the following steps: pre-oxidizing the part of the sealing metal workpiece, pre-vitrifying the part of the sealing metal workpiece, and sealing the glass and the pre-vitrified part of the sealing metal workpiece through heating. The glass-metal sealing process of the present invention has greatly lowered sealing temperature, greatly shortened sealing time, raised sealing quality, simplified sealing equipment and lowered production cost.

Description

technical field [0001] The invention relates to a glass-metal sealing technology, in particular to a glass-metal sealing technology for solar vacuum heat collecting tubes. Background technique [0002] Solar energy is an inexhaustible green energy source. In the utilization of solar energy, a kind of solar vacuum heat collecting tube is usually used to collect the heat of solar energy more effectively. The solar vacuum heat collecting tube includes a glass tube, and a metal heat absorbing body is arranged in the glass tube, and vacuum technology is used to make the inside of the glass tube in a vacuum state, so as to minimize the loss of heat energy. At least one end of the metal heat absorber protrudes from the outer end of the glass tube, and is connected to devices required for heat energy, such as water tanks, headers, etc. In order to maintain the vacuum state in the glass tube, the problem of sealing connection between the glass tube and the protruding end of the met...

AI Technical Summary

Problems solved by technology

The disadvantage is: the melting point of lead solder is low, and the vacuum exhaust temperature of the vacuum heat collecting tube is also reduced accordingly, so that it cannot be exhausted completely, so that the vacuum heat collecting tube will continuously deflate during use, which will affect its service life

However, when aluminum wire is used as sealing solder to manufacture vacuum heat collecting tubes, since the sealing temperature is 0.6-0.9 times the melting point of aluminum at 660°C, the state of aluminum wire is relatively hard, the glass is easily damaged during processing, and the yield is low, which is easy to cause slow Leakage, affecting product life

Moreover, the sealing temperature is high, the preheating time is prolonged, and the production efficiency is not high

[0008] In addition, when using the above-mentioned heat-pressing sealing process at present, it is necessary to apply pressure to the glass tube perpendicular to the end of the glass tube, and the pressure station of the production line extends underground, which not only increases the complexity of the production line, but also What is limiting the length of the vacuum collector tube

[0009] In addition, the glass of the existing vacuum heat collecting tubes generally adopts high borosilicate glass with a low expansion coefficient (the expansion coefficient is 3.3×10 -6 / °C), there is no metal with a matching expansion coefficient, which increases the difficulty of sealing regardless of traditional fire sealing or hot pressing sealing.

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