JPS6172637A - Tempering of flag glass - Google Patents

Abstract

PURPOSE:To manufacture a tempered flat glass forming little sharp fragments when broken, by using a pair of specific blast heads, and blasting a cooling medium against a flat glass heated above the distortion temperature. CONSTITUTION:A pair of blast heads 7, 8 used in the above process are fur nished with a number of cooling nozzles 11 characterized in that (i) the nozzles are arranged concentrically on the blast head and (ii) each nozzle 11 excepting that of the central region is inclined at 3-45 deg. to the perpendicular axis along the tangential direction of the concentric circle. A flat glass 4 heated above the distortion temperature is suspended with the hanger 5 between the opposite faces 12, 12 of the blast heads 7, 8, and a cooling medium (air, water mist, etc.) is blasted against the glass to effect the quenching and tempering of the glass 4.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for strengthening sheet glass, and in particular, when glass is crushed, the occurrence of 7-year edges (elongated fragments) is extremely small. It concerns a strengthening method.

As automobiles become lighter, tempered glass sheets are becoming thinner, and as tempered glass becomes thinner, shear 7 edges tend to occur more easily, and countermeasures against sharp edges have become important.

In other words, various laws and regulations regarding the breaking of tempered glass have been established from the viewpoint of the safety of the driver or passenger of a car, such as the J Engineering S Standard, the British Standard B85282, the European Economic Community (EEO) Standard, etc. These are limited to the range where the maximum and minimum number of fractures within an area of 5 tilt It must not contain any crushed pieces, and the maximum area of each crushed piece is also determined.

The present invention provides a reinforced plate glass that can prevent the occurrence of sharp edges and also passes the above-mentioned standards.
This relates to a strengthening method that is widely used in manufacturing reinforced glass for automobiles, buildings, etc. as well as automobile window glass. (Prior art) Conventionally, thin glass has been strengthened to meet the standards mentioned above. Processing is difficult, especially when the size of thin glass with a thickness of 3.5 or less is large, for example, 1 floor x 5.
00111111 or more, the difficulty increases, and it is almost impossible to obtain a tempered plate glass that passes the above standard using the air strengthening method.

Therefore, several strengthening methods have been proposed that attempt to overcome the above-mentioned standards by appropriately arranging regions where the average tensile stress is slightly larger and smaller than other parts.

For example, in Japanese Patent Application Laid-open No. 52-121620, a large number of regular quenching jets are blown onto both sides of about 3 sheets of crow sheet heated to near the softening point, and compared to the conventional nozzle position and jet amount. or by sliding the jet nozzle parallel to the glass surface a distance equal to the distance between adjacent nozzles, or by sliding it circularly with an appropriate radius, or By placing the nozzle in a stationary state, regions with a low reinforcement degree and intermediate regions with a reinforcement degree are appropriately scattered adjacent to the region with a high reinforcement degree, and the center-to-center distance t of the adjacent regions is
33516 and Japanese Patent Application Laid-Open No. 54-33517 have gas supply holes, gas exhaust holes, gas exhaust holes, waste supply nozzles, etc. arranged in an orthogonal grid pattern. , by making the nozzle at a slight angle with respect to the advancing direction of the glass plate, attempts are made to prevent the formation of reinforcing striations, and in accordance with Japanese Patent Application Laid-Open No. 54-33.
No. 515 discloses a method in which a glass plate heated to a high temperature is advanced in a rapidly cooled waste, and then opened and stopped for a predetermined period of time, and cold gas flows in a specific direction from a gas supply hole to cool a local area of the glass plate. A reinforcing method for obtaining a reinforced curved crow plate is disclosed in Japanese Patent Application Laid-Open No. 1983. -33516
JP-A No. 54-335 discloses that a ladder-shaped tempered glass for the side windows of automobiles can be obtained by flowing a localized gas sinit directed at the top surface of a glass plate, and a method for manufacturing the same is disclosed.
Publication No. 17 discloses a method for obtaining side and rear window glass for automobiles and a method for strengthening the same by applying repetitive pulsations in relation to the forward speed of the glass plate.

On the other hand, the present applicant previously disclosed in Japanese Patent Application No. 71417/1983 that cooling nozzles on the frust head surface are arranged concentrically in a polar coordinate system outward from the center of the surface to achieve rapid cooling. We are proposing a method for strengthening sheet glass.

(Problem to be solved by the invention) However, the previously published Japanese Patent Application Laid-Open No. 52-121
No. 620 to Japanese Patent Application Laid-Open No. 54-33'i17 relate to strengthening the wind cooling of a blast head in which the conventional arrangement of cooling nozzles is arranged vertically and horizontally in a grid pattern or diagonally in a staggered pattern. Considering the crack development mechanism, this is unreasonable. That is, it is known that cracks develop in a direction perpendicular to the principal stress (σI).

In orthogonal systems, σ is generally too sharp in a certain region, so sharp edge-like cracks tend to occur frequently. Further, there are disadvantages in that the difference between the maximum and minimum values of the number of fragments is large, and the maximum area of the fragments tends to exceed the above-mentioned standard. Therefore, although various auxiliary means are attempted to solve this problem, the effects vary depending on the shape of the glass plate, etc., and it is necessary to select various requirements for implementation.

According to the above-mentioned proposal of the present applicant, the number of sharp edges can be extremely reduced by arranging concentric cooling nozzles, which is different from the conventional one, and the maximum and minimum values of the number of fractures can be significantly reduced. The difference can also be reduced,
Although the above-mentioned standards can be satisfactorily met, there is an even greater need for a product that can meet the above-mentioned standards and be produced reliably and efficiently even under more severe conditions.

(Means for solving the problems) The present invention has been made by focusing on the above-mentioned problems,
The present invention aims to provide a method for strengthening plate glass that can fully meet the conventional demands.

That is, in a method for strengthening plate glass in which a glass plate heated above its strain point is strengthened by spraying a cooling medium from cooling nozzles arranged in a pair of blast heads, the center of the plate glass is placed on the mounting surface of the cooling nozzle of the blast head. Cooling nozzles are disposed concentrically outward from the center, and the cooling nozzles other than the center are inclined from 3 to 45'' in the tangential direction of the concentric circles with respect to the blast head surface. This is a device that rapidly cools plate glass, and by spraying the cooling medium at a specific angle in the tangential direction of the concentric circles, a highly strengthened part of the plate glass surface corresponding to the cooling nozzle is formed in a concentric circle shape. The value of the small principal stress that is formed can be increased to a certain extent, and the value of the relatively large principal stress can be reduced, so that a peculiar stress field is no longer generated, and the occurrence of a negative edge can be prevented. It is possible.

At this time, regarding the inclination of the cooling nozzles arranged concentrically on the blast head surface, the angle θ with respect to the vertical axis on the surface is set at 3 to 45', preferably 5 to 25 degrees.
This is because if it is smaller than f, the effect of having an angle disappears, and if it is larger than 4 degrees, the cooling ability of the refrigerant will be extremely reduced. The preferable angle 5 to 2f is based on the reason that the manufacturing stability is remarkable.

In addition, the intervals R and S between each cooling nozzle are not particularly determined, and the size of the glass plate, the plate thickness,
Although it varies depending on other conditions, preferably R is 2
0 to 40KI+I, S is 10 to 30w++. In other words, these values are determined by the distance between the centers of most of the principal stresses in the adjacent areas, the tolerance of the length of the sharp edge in each of the above standards, and the cooling capacity of the cooling medium and cooling nozzle, etc. Below the lower limit, after the cooling medium exchanges heat, the medium whose temperature has risen will be insufficiently exhausted, resulting in a decrease in cooling performance.

Furthermore, when sheet glass is strengthened, it is usually difficult to strengthen the central area of the sheet glass compared to the outside, but by arranging the cooling nozzle as described above, the temperature of the central area is slightly lower than that of the surrounding area. Even if the sheet glass is cooled sufficiently, the reinforcement between the central area and the peripheral area can be made uniform, and there is no need to try to raise the temperature of the central area of the sheet glass, which prevents the peripheral area from being heated more than necessary. Since there is no heating equipment, it is sufficient to heat the sheet glass to be tempered using a normal heating device.
It is possible to prevent the occurrence of defects at the front stage, such as stretching at the parts.

Furthermore, even if the temperature in the central area is higher than the area around the temporary storage area,
It is possible to obtain the required degree of reinforcement.

Here, plate cuffs heated above the strain point are, for example, 600
It was heated to a temperature of ~700°C.

A pair of blast heads may have a flat cooling nozzle mounting surface for strengthening flat glass sheets as shown in Figure 2, or may have a convex and concave shape for strengthening curved glass sheets. There may be.

The cooling medium may be a commonly used cooling medium such as air or water mist, but is not particularly limited to these.

The arrangement formed by the cooling nozzle on the plasto-rad surface may be circular, elliptical, spiral, or polygonal. You can.

It is preferable that the directions of inclination of the cooling nozzles on the pair of blast head surfaces are symmetrical, but the present invention is not necessarily limited to this.

In addition, if the glass plate requires curved tempered glass for the purpose of use, after bending with the Fres mold of the invention described in Japanese Patent Application No. 57-226406 filed by the present applicant etc. in the Fres mold forming process. By implementing the cooling enhancement method of the present invention in combination, a synergistic effect can be achieved. In addition, the applicant has also filed a separate patent application filed in 1986-21.
The same effect can be obtained even if it is implemented in conjunction with the method of installing a baffle plate member as described in No. 4173.

Next, the method for strengthening plate glass according to the present invention will be explained based on the drawings. The drawings show one embodiment of the present invention. The plate glass is hung from a hanging tool 5 and suspended in a heating furnace to a temperature higher than the strain point, for example, 600 to 700° C., and then transferred to a cooling strengthening device A for strengthening processing. The cooling reinforcement device A consists of a right side blast head 7 and a left side blast head 8, and the left and right blast heads 7 and 8 are provided with pipe members 9 and IO from a cooling medium supply source behind them, and are supplied with cooling medium. A concentric cooling nozzle 11 with an inclination is disposed on a cooling nozzle mounting surface 12 on the front surface. The left and right blasts 1 have a plate blade lath 4 in the center of the space formed by the heads 7 and 8;
are moved at equal intervals and a cooling medium is sprayed from both cooling nozzles 11 to perform strengthening treatment. Normally, the blast head is capable of minute sliding movements, such as up and down, left and right, or in circles. Further, the plate glass 4
When moving, it is preferable that the center of the concentric circle formed by the cooling nozzle coincides with the position of the crushing start point 3 (the center of the glass plate to be strengthened) specified in the crushing test on the reinforced plate glass.

Furthermore, the cooling nozzle 11 may have a circular shape as shown in FIG.
It may have an elliptical shape as shown in the figure, or it may have a spiral shape as shown in FIG. These cooling nozzles are arranged in concentric circles in a polar coordinate system, but the distance between the cooling nozzles becomes wider as they go outside the concentric circles.
If the distribution becomes too coarse and there is a problem with uniform reinforcement, the distance should be 45 cylinders, preferably 35f + lf.
The same cooling nozzle as above is additionally arranged in the middle so as not to exceed f1. At that time, if the distance between the cooling nozzles is too short, it will be difficult to discharge the cooling medium that contributed to strengthening, which will cause insufficient strengthening and uneven strengthening, so it is necessary to consider the nozzle diameter and arrange it appropriately. There is. Of course, as described above, the cooling nozzles may be arranged at equal intervals.

FIG. 6 shows a conventional blast head in which cooling nozzles are arranged diagonally in a staggered manner on the cooling nozzle mounting surface of the blast head.

(Examples) Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 6 l2oo x 70 heated to a temperature of 70-680°C
A plate glass with a thickness of 3.0 mm is shown in Figures 1 and 2.
With the cooling nozzle arrangement and reinforcing device as shown in the figure, cooling nozzles with normal nozzle effective inner diameters are used, the distance between the cooling nozzles is R = 30 mm, S = approximately 218 mm, and the inclination of the nozzles is the tangent of the concentric circle. An angle of 0 is set in the direction, the distance between the nozzle tip wheel 3 and the cuff surface is 30 mm, the blast head is slid up and down by about 40 degrees, and the air pressure is 2500.2300.2100 ml (] s
Examples 1 to 1 in Table 1 were subjected to air-cooling strengthening treatment at an air content of 560 Nw/m1n.

Comparative Example For comparison with the present invention, a blast head with a conventional staggered cooling nozzle arrangement as shown in FIG. 6, and a distance between the cooling nozzles with r of 24 fMn and B of 25 Comparative Examples 5 to 7 in Table 1 are examples in which the reinforcing treatment was carried out using the reinforcing device shown in Table 1 under the same conditions.

In addition, the applicant previously filed the patent application No. 58-7141.
The strengthening method described in No. 7 consists of arranging cooling nozzles on the blast head surface outward from the center of the surface in a concentric circle in a polar coordinate system.9 The strengthening process was performed under the same conditions as above. These are Comparative Examples 8 to 10 in Table 1.

Table 1 shows the test results. The degree of reinforcement of sheet glass is determined by the crushing starting point (zero point) of 1, 2, 3 in the crushing test for tempered sheet glass described in the BS standard (B55282).
It is expressed as the number of fractures when crushed in , and the number of broken edges is defined as the length of the fractured pieces is 608 or more and the ratio of length to width is greater than the current one.

In addition, J Engineering S standard (J Engineering S R3212) and FIF
Almost the same numerical values were obtained in the test results according to the O standard, and the representative values are shown in the table below.

In the table, the number of fractures and the number of sharp edges are the numbers at any position excluding the area within 20fa from the periphery of the plate crow and within a radius of 75wn from the point of impact.

Chapter 1 Table Note 1) Approximately the center point of the specimen.

Note 2) Point +00m from the midpoint of the long side toward the center.

(Effects of the Invention) As is clear from the foregoing, according to the present invention, the cooling nozzles are disposed concentrically outward from the center of the blast head, and the cooling nozzles other than the center of the blast head are arranged concentrically outward from the center. 3 to 3 in the tangential direction of the concentric circle to the blast head surface.
Since the lath plate is tilted at a 45° angle and strengthened by rapid cooling, it is possible to prevent the occurrence of sharp edges when the lath plate is fractured, and to reduce the number of fractures, as is clear from Table 1. The difference between the maximum value and the minimum value of can be further reduced, and a reinforced glass with a uniform degree of reinforcement can be obtained over the entire sheet glass, resulting in even higher safety.

That is, 1. Not only TIS standard and BS standard, but also FKC
It is possible to obtain a safety glass for automobiles, etc. that passes standards and other regulations, and it also has many industrial benefits because the cooling air pressure can be lowered in the manufacturing process. It has a significant effect.

[Brief explanation of the drawing]

1 is a schematic front view and a partial side view of a nozzle mounting plate showing the nozzle arrangement of the present invention in the air cooling blowout nozzle arrangement of the apparatus shown in FIG. 2. FIG. FIG. 2 is a schematic side view showing an air-cooling strengthening device for glass plates used in the practice of the present invention. FIG. 3, FIG. 1, and FIG. 5 are schematic front views of other embodiments showing the arrangement of air cooling nozzles. FIG. 6 is a front view showing an example of the arrangement of cooling nozzles on the surface of a conventional blast head. 4 ... Plate glass cup ... Cooling reinforcement device 7.8 ... e Blast head 111 @ cooling nozzle JS, r, s ... Cooling nozzle interval distance θ
...Inclination of the cooling nozzle 13 ...Nozzle tip patent applicant Central Glass Co., Ltd. Fig. 3, 11 Fig. 4

Claims (1)

[Claims] In a method of strengthening plate glass that is heated above the strain point by spraying a cooling medium from cooling nozzles arranged in a pair of blast heads, the plate glass is strengthened by spraying a cooling medium on the cooling nozzle mounting surface of the blast head from the center of the surface. Cooling nozzles are arranged in a concentric circle facing toward the glass plate, and the cooling nozzles other than the center are inclined at an angle of 3 to 45 degrees in the tangential direction of the concentric circle with respect to the vertical axis of the frust head surface. A method for strengthening plate glass characterized by rapid cooling.