JPS63270327A - Production of heat treated glass plate - Google Patents

Abstract

PURPOSE:To uniformly cool and strengthen a glass plate in sifted contact position with a roller, by cooling the glass plate heated to near softening point in heat oven in a cooling part while sifting the changing position before and behind and reciprocating the glass plate plural times. CONSTITUTION:A glass plate G carried from an inlet part 2 by a carrying roller 7 is heated to near the softening point in a heat oven 3. Then the glass plate G is cooled in a rapidly cooling part 4 and carried to a gradually cooling part 5, where air is permitted to flow to glass plate G while reciprocating the glass plate G and gradually cooled to about 400 deg.C. Then the glass plate G is returned to the rapidly cooling part 4 and after the glass plate is cooled until the temperature capable of taking up, the glass plate G is taken out fro a taking-up part 6 as a reinforced glass. In the above-mentioned reinforced glass production apparatus 1, the glass plating G is reciprocated before and behind plural times in the gradually cooling part 5 and maintained not so as to sift the changing position of each reciprocation. Thereby the glass plate G is uniformly cooled without doubling the position rapidly cooled in contact with the roller 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing tempered glass in which compressive stress is generated on the surface of a glass plate by cooling.

(Prior art) Generally, to manufacture a tempered glass plate, the glass plate is heated in a heating furnace to near its softening point, and then cooled to apply surface compressive stress to the surface of the glass plate and to apply stress in the thickness direction of the glass plate. A central tensile stress is generated inside the reference.

In order to manufacture a normal tempered glass plate, the glass plate taken out of the heating furnace is immediately carried into a quenching section to cool the glass plate within a short time.

In addition, the surface compressive stress (
300 to 600 kg/cm2) to prevent it from breaking into small pieces when broken, the glass plate is taken out of the heating furnace and transported into an annealing section. The temperature is allowed to drop slowly while passing through.

In order to slowly lower the temperature of the glass plate in the annealing section, it is conceivable to increase the length of the annealing section, but this is disadvantageous in terms of space. Therefore, conventionally, the glass plate is moved back and forth within the slow cooling section to achieve the same effect as using a long slow cooling section.

(Problems to be Solved by the Invention) As described above, if the glass plate is made to reciprocate in the annealing section, the glass plate can be annealed without drastically reducing the conveyance speed. At the switching position, the glass plate stops, albeit momentarily. Moreover, since the roller has high thermal conductivity, the part of the surface of the stopped glass plate that is in contact with the roll is cooled more strongly than other parts, and the surface compressive stress generated in this part is greater than that in other parts. becomes. In particular, if the stop positions overlap when reciprocating a number of times, the difference in surface compressive stress cannot be ignored and may even cause optical distortion.

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the present invention, when the glass plate is cooled by reciprocating the glass plate a plurality of times within the cooling unit, the switching position of the reciprocating movements is shifted.

(Function) Since the switching positions of the reciprocating movement of the glass plates are shifted, the positions of the stopped glass plates that contact the rolls do not overlap.

(Example) Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall view of a manufacturing apparatus for heat-treated glass sheets that implements the method of the present invention. A quenching section 4 is provided in the quenching section 4, a slow cooling section 5 is provided downstream of the quenching section 4, a picking up section 6 is further provided downstream of the slow cooling section 5, and conveyance from the crowd section 2 to the picking up section 6 is provided. Rollers 7 . . . are provided, and the glass plates G are successively passed over the transport rollers 7 in a horizontal state. As shown in FIG. 2, the structure of the slow cooling section 5 is that box sections 8.8 are disposed above and below the transport rollers 7..., and the opposing surfaces of these box sections 8 are covered with heat reflecting plates 9.9. Small holes 9a for blowing out cooling air are formed in this heat reflecting plate 9, and each box part 8 is
A blower 10 is provided, and the air supplied from the blower 10 into the box part 8 is blown onto the surface of the glass plate 0 being conveyed on the conveying roller through the small hole 9a, thereby cooling the glass plate G.

Here, when manufacturing hand-strengthened glass sheets, the process speed (800 to 7
50mm/5ec) to pass through the rapid cooling section 4 to the slow cooling section 5.
The glass plate G is moved back and forth in this slow cooling section 5 to slowly cool it to about 400°C, and then returned to the rapid cooling section 4.
After being cooled down to a temperature at which it can be taken up (approximately 50°C), the glass plate G is passed through the annealing section 5 again, and then taken up from the taking up section 6.

Here, the reciprocating motion of the glass plate G in the annealing section 5 is the third
As shown in the graph in the figure, the reciprocating switching positions P should not overlap. In other words, the switching position of each reciprocating motion is 20 m.
Make sure that the contact positions of the stopped glass plates with the roller rough do not overlap. Note that in the graph of Figure 3, the switching positions are shifted at equal intervals, but it is not necessary to shift them at equal intervals; in short, it is sufficient to prevent the same point on the glass plate from stopping on the roller. .

(Effects of the Invention) As explained above, according to the present invention, when a heated glass plate is cooled and strengthened while reciprocating within the cooling unit, the switching position of the reciprocating movement is shifted, and the same By preventing a point from stopping on the roller multiple times, the glass plate is cooled strongly locally, which prevents the disadvantage of generating surface compressive stress that is different from that in other areas, resulting in uniformly strengthened glass. A board is manufactured. Further, since the roller does not come into contact with the same location on the glass plate and stop, the occurrence of optical distortion can also be suppressed.

[Brief explanation of drawings]

Figure 1 is an overall view of the manufacturing equipment for carrying out the method of the present invention;
The figure shows the internal structure of the slow cooling section, and FIG. 3 is a graph showing the relationship between the position of the glass plate in the slow cooling section and time. In the drawing, 3 is a heating furnace, 4 is a rapid cooling section, 5 is a slow cooling section, and 7 is a heating furnace.
is a conveyance roller, and G is a glass plate.

Claims (1)

[Claims] In a method for manufacturing a heat-treated glass plate, the glass plate heated in a heating furnace to near its softening point is carried into a cooling section, and the glass plate is cooled in this cooling section to generate surface compressive stress on the surface of the glass plate. A method for manufacturing a heat-treated glass plate, characterized in that the glass plate is reciprocated back and forth a plurality of times within the cooling section, and the switching position of each reciprocating movement is shifted.