JPH0757698B2 - Method for manufacturing heat-treated glass plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a method for producing a tempered glass in which a compressive stress is generated on the surface of a glass sheet by way of example.

(Prior Art) Generally, to manufacture a tempered glass plate, the glass plate is heated to near the softening point in a heating furnace, and the surface compression pressure is applied to the glass plate surface by cooling the glass plate in the thickness direction of the glass plate. A central tensile stress is generated inside the reference.

Here, in order to manufacture an ordinary tempered glass plate, the glass plate carried out from the heating furnace is immediately carried into the quenching section, and the glass plate is cooled within a short time.

In addition, in order to manufacture so-called semi-tempered glass sheets that have smaller surface compressive stress (300 to 600 kg / cm ² ) than ordinary tempered glass sheets and do not become fine fragments when they break, they are carried out from the heating furnace. The glass plate is carried into the slow cooling section, and the temperature is slowly lowered while passing through the slow cooling section.

Then, in order to slowly lower the temperature of the glass plate in the slow cooling portion, it is possible to increase the length of the slow cooling portion, but this is disadvantageous in terms of space. Therefore, in the prior art, the glass plate is reciprocated in the slow cooling section so that the same effect as when using the long slow cooling section is exhibited.

(Problems to be Solved by the Invention) As described above, if the glass plate is reciprocated in the annealing part, the glass plate can be annealed without significantly lowering the conveying speed. At the motion switching position, the glass plate stops for a moment. Since the roller has high thermal conductivity, the part of the stopped glass plate surface that is in contact with the roll is cooled more strongly than other parts, and the surface compressive stress generated in this part is larger than other parts. . In particular, when the stop positions overlap each other when the reciprocating motion is repeated many times, the difference in the surface compressive stress becomes non-negligible, and further causes optical distortion.

(Means for Solving the Problems) In order to solve the above problems, in the present invention, when the glass plate is reciprocated a plurality of times in the cooling section to cool it, the switching position of the reciprocation is shifted.

(Operation) Since the switching positions of the reciprocating movement of the glass plate are deviated, the stopped position of the glass plate does not overlap with the roll contact position.

(Example) Below, the Example of this invention is described based on an accompanying drawing.

FIG. 1 is an overall view of an apparatus for producing a heat-treated glass plate for carrying out the method of the present invention. In the producing apparatus 1, a heating furnace 3 is arranged downstream of an entrance 2 of a glass plate G, and downstream of this heating furnace 3. A quenching section 4 is provided, a gradual cooling section 5 is continuously provided downstream of the quenching section 4, and a pick-up section 6 is further provided downstream of the gradual cooling section 5. Are provided so that the plate glass G can successively pass over the conveying roller 7 in a horizontal state. As shown in FIG. 2, the structure of the slow cooling unit 5 is such that the transport roller 7 ...
8 are arranged, and the opposing surfaces of these box portions 8 are heat reflection plates 9, 9
The heat-reflecting plate 9 has a small hole 9a for blowing cooling air ...
And the blower 10 is provided in each box portion 8 and the air supplied from the blower 10 into the box portion 8 is formed into a small hole.
Glass plate G conveyed on the conveying roller 7 via 9a
The glass plate G is cooled by spraying on the surface.

Here, when manufacturing a semi-tempered glass plate, it is faster (600-750 mm / s) than when manufacturing ordinary tempered glass.
In ec), the glass plate G is passed through the quenching section 4 and carried into the slow cooling section 5, and the glass plate G is reciprocated in the slow cooling section 5.
After gradually cooling to about 400 ° C., returning to the quenching section 4 again and picking up and cooling to a possible temperature (about 50 ° C.), after passing through the annealing section 5 again, the glass plate G is picked up from the picking section 6. .

Here, the reciprocating motion of the glass plate G in the slow cooling unit 5 is the third
As shown in the graph of the drawing, the switching positions P of the reciprocating motions should not overlap. That is, the switching position of each reciprocating motion is shifted by about 20 mm so that the contact positions of the rollers 7 of the stopped glass plate do not overlap. In the graph of FIG. 3, the switching positions are shifted by equal intervals, but it is not always necessary to shift them by equal intervals, and the point is that the same portion of the glass plate does not stop on the roller. .

(Effect of the invention) As described above, according to the present invention, when the heated glass plate is reciprocated in the cooling unit while being cooled and strengthened, the reciprocating switching position is shifted so that the same glass plate is used. Since the part does not stop on the roller multiple times, the disadvantage that the glass plate is locally strongly cooled and the surface compressive stress different from other parts is prevented is prevented, and the glass is uniformly reinforced. The board is manufactured. Further, since the roller does not come into contact with the same position on the glass plate and stop, the occurrence of optical distortion can be suppressed.

[Brief description of drawings]

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

Claims (1)

[Claims] 1. A heat-treated glass plate in which a glass plate heated to near a softening point in a heating furnace is carried into a cooling part and the glass plate in the cooling part is cooled to generate surface compressive stress on the surface of the glass plate. The method for manufacturing a heat-treated glass plate according to the above item (1), wherein the glass plate is reciprocated back and forth a plurality of times in the cooling unit and the switching position of each reciprocation is shifted.