FI88909C - Method and apparatus for bending and / or tempering glass - Google Patents

Description

! 88909

METHOD AND APPARATUS FOR BENDING AND / OR HARDENING GLASS

The invention relates to a method and apparatus for bending and / or tempering glass, in particular glass which is difficult to bend, such as car windscreens, rear windows and side windows.

The glass is bent and tempered by various methods. In one of the earlier and still used methods, glass was heated in a roller oven. Then, as the glass moved forward, the roller oven turned into a gas bed. This means that there was a plane of holes through which hot air was blown, which at the same time heated the glass and supported it on a thin mucosa.

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As the glass began to be at the bending temperature, this gas bed gradually changed from planar to having the desired bending, usually almost radial in shape. The glass thus flexed by gravity into the shape of a gas bed, but since it was constantly moving forward, it is understandable that the glass cannot have conical or complex shapes. Figure 1 shows a schematic diagram of such a so-called gas heart arrangement.

In another bending method known from French patent 2567508 (Fig. 2), after the glass 3 has been heated in the roll furnace 2 to the bending and tempering temperature, the glass 3 is molded against a mechanical mold 4 by blowing hot air through the air duct 7 with a blower 6. the glass 3 is pressed into the shape of the mold 4. In this case, it is utilized without blowing force. This method is outlined in Figure 2. The disadvantages of this method are, among other things, that the heating of the glass to tempering temperature must be performed on the roll rolls, so that hot rolls easily become surface defects. its position in relation to the mold is not exactly in the right place, the bending is not correct. Positioning glass at tempering temperature in a hot 2 88909 oven is difficult. Additional heating of the glass is also difficult, and it can no longer be done, for example, from below with the help of radiation e.g. due to the rollers and blow holes below. Since the glass against the mold is formed only by the kinetic energy of the air produced by blowing air, the bending-bending time is long, the amounts of air required are large and the method is energy-wasting and difficult to control.

It is also possible to use a method known from Finnish patent application 903397, in which the glass is bent into the shape of an edge mold so that, e.g. by utilizing a suspended ceiling system, a pressure difference can be created above and below each other in connection with the glass. part or all of the L5 glass may be further heated to a uniform and sufficiently high temperature to be tempered. This method cannot be used to produce glasses with S-shaped or complex shapes, because the pressure difference can only compensate for gravity / a, but not actually mold the glass.

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The device and method according to the invention provide a decisive improvement in the above-mentioned drawbacks. To achieve this, the method and apparatus according to the invention are characterized by what is set forth in the characterizing part of claims 1 and 6.

The advantages of the invention are its suitability especially for heavy glass shapes. The invention can be used not only to make car rear windows and side windows, but also, for example, windshields bent into an S-shape, certain interior and architectural glasses at a considerably cheaper price than currently available machines and methods. The bending / tempering process is easier to control with the method and apparatus of the invention because the glass is bent and heated to the highest temperature so that it is stationary, stationary, during the final stage, making it susceptible to defects due to its plasticity. The airflows of the blow are lower than in the previously used upper mold method, because the bending is decisively facilitated by the edge mold. Also, at the hottest temperature 3 88909 in the method according to the invention, the central part of the glass never rests on a mechanical support or rollers, whereby the quality of the glass is made flawless.

5 It is known to use mechanical pushers on the other side of the glass as well, but each form of glass would require its own pusher and mechanical pushers easily leave marks on the glass. The location of the mechanical presses in a hot space entails a lot of maintenance and replacement costs. When pressed with the air pressure according to the present invention, the printing is smooth and no surface defects remain. Likewise, the air pressure adapts to any surface, and no separate molds on the air pressure side are required. For these reasons, the invention has the quality-improving properties of glass 15 compared to previous methods and provides cost savings.

Difficult placement of the glass inside the furnace does not need to be done at all or it can be done, for example, when the glass is at a temperature well below 600 ° C, making it easier than at about 620 ° C, where it has to be done by competitive methods.

The method and apparatus according to the invention are described below with reference to the accompanying drawings. The figures show: Figure 1 is a schematic diagram of a so-called from the "gas heart" furnace and Fig. 1A section A-A of Fig. 1.

30 Figure 2 shows a solution according to the above-mentioned French patent.

Figure 3 shows a schematic cross-section of an arrangement according to the invention.

Figures 4 and 5 show modifications of the invention.

Figure 1 shows a schematic diagram of the operating principle of a gas heart furnace, in which glass is introduced on rollers 1 into a preheating stage, after which the furnace turns into a gas furnace 2 with blown gas supporting glass 3. When glass 3 is at a bending temperature, the gas bed gradually changes . From this step, Figure 1A is a section from point A-A in Figure 1. Hardening 5 was then performed last. Because the glass moved forward all the time, it could not have conical or complex shapes.

According to the invention, the glass sheet 3 can be formed, in particular, 0 into a difficult bending shape. This is accomplished by using a fixed size mold 14 that is in the shape of the desired glass and is generally male. The shaping of the glass 3 is achieved by utilizing the edge mold 15 and combining static or dynamic air pressure with the use of the edge mold 15.

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If, in addition to the edge mold, a preferred static pressure is used for the final bending of the glass, the second half of the furnace, (bottom in the figure), should form a closed space on one side (top of the figure), slightly smaller than the size of the glass. The shape of the opening corresponds to the shape of the glass and the edges of the opening correspond to the shape corresponding to the bending of the edge of the glass. It is most advantageous to provide this opening by means of a detachable collar 20 which is easy to change to suit the type of glass.

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As the glass covers the opening, a closed chamber 21 is formed from the half of the furnace block, into which it is possible to create a pressure by blowing air through a pipe 24 by means of a fan 16 to bend the glass against a full mold 30 on the other side. For example, with electrical resistors 23, the temperature of the glass can be further raised. With the lifts located under the furnace, the lower part of the furnace can be moved vertically with respect to the entire mold 14, whereby bending becomes possible. The figure also shows a chamber 25 in which air can be stored, which compensates for changes in air volume caused by pressure fluctuations and in which air can be heated to a suitable temperature by resistors 26. Directional valve 27 allows return of leaking air to the pressurized part of the furnace during bending. 26 of 5 88909 ta.

Figure 4 illustrates another way of providing a pressurized chamber 21 with heating elements from the bottom of a furnace and with which the described combined bending and heating process is achieved. The necessary vertical movement is now performed by means of a plate 19 (with seals), whereby the other walls of the chamber remain in place. The method of Figure 4 does not differ from the method of Figure 5 other than its mechanical implementation.

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If the static pressure were replaced mainly by the use of air kinetic energy, i.e. dynamic pressure, such a closed part of the furnace block would not be needed. Figure 3 shows such a schematic view of a furnace or furnace block 11 in which the glass 15 3 is bent up / down against the mold 14 movable by the lifting member 12 by blowing hot air against the glass with a heat-resistant blower 16. Resistors 23 can provide additional heat to the air. With the edge mold 15, the edges of the glass are bent against the entire mold 14.

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Either the edge mold or the full mold or both must be vertically movable. Bending would then be accomplished by pressing the edge mold 15 or collar 20 and the full mold 14 against each other when the glass 3 is somewhat at a bending temperature (about 550-600 ° C) and at the same time increasing the pressure or bending force due to air blowing to bend. the shape of the surface of the size mold 14 of the glass 3 while heating the glass to a final temperature of about 620 ° C for the glass to be tempered, often slightly lower for bendable ones alone.

Mechanical contact between the hot glass and the mold can cause surface defects in the glass. In addition, especially for heavier glasses with S-shapes, there is a relative movement between the glass and the mold, which would further significantly increase the surface defects of the glass. For glasses decorated with screen printing inks, this prevention of mechanical contact is particularly important. To eliminate mechanical contact, holes (arrows 22) may be added to the mold for air blowing 6 88909, in which case the glass is in fact molded against the mucosa as described above. Blowing through these holes can also be used to heat the glass. Holes in the mold can be added to the mold 14 with both the options shown in Figures 3 and 5 4 and 5.

In all embodiments of the methods of the invention, the glass 3 can now still be heated quite easily, in addition to radiation from below, e.g. by means of hot air and from above 10 by the hot mold 14 glow and maintaining the hot air temperature so that it heats the glass to tempering temperature (about 610-620 ° C). , depending on the thickness of the glass.

In the manufacture of tempered glass, the glass can be introduced into the hardened-mouth, possibly with the same edge mold with which it is bent. However, when holes are used in the full mold, it can also be used to lift the glass, e.g. to transfer the glass to the tempering frame. The tempering frame could in this case be outside the oven. It is also possible to support the glass 20 by blowing it vigorously against the size mold 14 so that it completely disengages from the edge mold, leaving such a gap between the edge mold and the glass that a tempering frame can be introduced under the glass from outside the furnace. By lowering the pressure, the glass lands on the tempering frame. In this case, there is always a mucosa between the glass 25 and the full mold, which has a very positive effect on the quality of the glass, e.g. mechanical contact with the glass is minimized.

The preliminary steps of the method according to the invention could consist of, e.g., initial heating, e.g. in a furnace such as a windscreen bending furnace. Preheating can also be performed in a te-furnace, in which case the glass should be lifted with a vacuum lifter or some other system to be bent to the edge mold. In a low-capacity furnace, the glass can also be heated from the beginning in the bending compartment according to the invention. After the glass has been shaped in the above-mentioned manner, in the case of tempered glass, it is heated to a tempering temperature at which it can be tempered. After tempering, the glass is cooled as usual.

7 88909

It should be noted that the invention has been described with reference to only one preferred embodiment thereof. However, this is in no way intended to limit the invention to this 5 example only, but many modifications are possible within the scope of the idea defined by the following claims.

Claims (6)

8 88909 PATENT CLAIMS p A method of bending glass (3) and heating it to a final temperature (usually the highest temperature), in which method 5 glass (3) is bent by the interaction of an edge mold (15) or collar (20) and a gas, usually atmospheric pressure, on one side of the glass (3) against the size mold (14), characterized in that the glass (3) is shaped to correspond to the surface of the size mold (14) while raising the temperature of the glass (3) to the temperature required for bending and / or tempering on the mold (14) side by either the mold (14) or by means of or by a combination of air blown through the holes (22) therein and by means of air or radiation blown on one side or by a combination of these until the desired degree of bending and / or temperature of the glass is reached. A method according to claim 1, characterized in that on the side of the glass edge mold (15) or collar (20) and the bending pressure of the club there are heating resistors (23) or air blowing devices (16) or other heating devices with which the glass (3) can be during bending heats to the higher temperature required by the process. Method according to one of the preceding claims, characterized in that holes (22) are arranged in the upper mold (14) and are provided with blowing devices for blowing hot air between the mold (14) and the glass (3) to heat the glass (3) and / or or to keep 30 separate from the full mold (14). Method according to one of the preceding claims, characterized in that the force of the lower blow can be increased so that the glass (3) remains against the size mold (14) 35 even if the distance between the blow and the edge mold (15) and / or collar (20) from the glass (3) is added to transfer the glass (3) to e.g. the tempering frame. A method according to claim 1, characterized in that either a full mold (14) or an edge mold (15) or a collar (20) corresponding to said mold. the shape and size of the glass or all of these can be moved in the up / down direction by means of actuators so that the bending and heating process is possible and horizontal shifts of the edge mold so that glass transfers to and from the bending / heating compartment are possible. Apparatus for bending and heating glass, including 10 furnaces or furnace parts for final heating and bending of glass (3), characterized in that the glass edge mold (15) or collar (20) and at the same time the bending pressure side have heating resistors (23) or without blowing devices (16) or other heating devices by which the la-15 (3) can be heated to a higher temperature required by the process during bending, and on one side of the glass (3) there is a size mold (14) corresponding to the size and shape of the glass with possible air holes (22) and glass (3) on one side of the edge mold (15), the area delimited by the collar (20) 20 against the surface of the glass (3) being pressurized by a fan (16), the pressure of which and the edge mold (15) or collar (20) bent to its final shape while also continuing to heat the glass (3) to the final temperature required by the process. '25