DE1025586B - Process for cooling glass plates - Google Patents

Description

The invention relates to a cooling method and a device for carrying out the method, in particular for the production of tempered glass or safety glass.

The most common method of tempering glass is to first place the glass in an oven hung and heated to a temperature at which it begins to soften and become semi-plastic. That Glass is then removed from the furnace and quickly cooled by placing cold air on its hot surface is directed. The cooling air is usually initially high pressure and is passed through a A plurality of fine openings in the system, for example in jet pipes or nozzles, before it hits the hot glass surface in order to achieve the cooling required to harden the glass, to obtain. The jet pipes or nozzles or the frame supporting them are or will be in many processes rotated so that the surface is cooled more completely and evenly.

During the above procedure to glass to harden, leads to satisfactory results, if it is done carefully, is the required one Apparatus difficult to handle and the process expensive to carry out because of the necessary high air pressure and the cost of producing large quantities of compressed air. A Another disadvantage is that the method is difficult to apply when glass pieces of irregular Shape, in particular of curved shape, are to be hardened.

According to the present invention there is an improved Cooling method and a device, in particular for the production of tempered glass, in Proposal brought.

According to the invention, a method for cooling a plate-shaped body consists in that this in a substantially perpendicular plane into a layer of cold solid discrete particles is brought while the layer is exposed to an upward flow of gas, wherein the The size and weight of the particles and the speed and type of flow are chosen in this way be that the force exerted by the current is sufficient to act on the free particles To compensate for gravity and expand the layer to allow movement of the particles, but this is not sufficient to convert the layer into a particle flow. A layer of solid discrete particles that produce such an upwardly directed gas flow in US Pat The way that it is exposed and thereby expanded, is referred to in the following as "cold fluidized bed of small separate solid particles «.

Method for cooling glass plates

Applicant:

Croxdale Engineering

Development Company Limited,

Aberford (UK)

Representative: Dipl.-Chem. Dr. W. Koch, Hamburg 4,

and Dr.-Ing. R. Glawe, Munich 27, Cuvilliesstr. 16,

Patent attorneys

Claimed priority:
Great Britain 16 July 1954

Francis George Audas, Cheadle Hulme, Cheshire

(Great Britain),
has been named as the inventor

The creation of fluidized beds of solid separated particles by means of a sufficiently fast, upward gas flow is known in the chemical industry, particularly in the cracking of Hydrocarbons, but this fluidized bed process has so far been used for a completely different purpose been, namely around finely divided catalyst material at high temperatures in intimate contact to bring with a moving stream of hydrocarbon vapor. The fluidized bed process with solid separate particles has also been used in milling, but in one for a completely different purpose, namely to remove the floating flour particles more easily.

The invention particularly relates to a method of tempering glass, taking advantage of the Use of a fluidized bed as a cooling device in such a method consist in that the amount of air required for the fluidized bed can be made small and only low pressure needs to have. The manufacture of a suitable container for the fluidized bed is simple and cheap. Furthermore, both curved and plate-like glass can be processed with equal ease.

In a preferred embodiment of the invention, a glass plate is perpendicular to its upper Edge hung up with known pliers and heated in an oven until it becomes semi-plastic. the Heating time of course changes with strength

709 508/199

of the glass to be treated and the temperature of the oven used, but generally that is the required one Time between 2Va and 6 minutes. The tongs on which the glass is hung are on attached to a slide above the furnace, and when the glass is semi-plastic it is pulled back of the slide taken out of the furnace in a horizontal direction along a rail. Small doors above the furnace and at the end of the furnace are automatically opened and enable this horizontal movement of the glass, the tongs and the slide. When the carriage has a predetermined Has reached the position on the rail provided outside the furnace, it is stopped, and a layer of air-thrown sand particles just below the Slide is located, is lifted by pneumatic devices so quickly that from the moment where the bottom edge of the glass comes in contact with the top of the layer until it is complete Immersing the glass in the layer only for a period of the order of one Second is needed. Sufficient quenching can be used to obtain satisfactory results of the glass in about 10 seconds; but this time can be changed depending on the degree of desired Hardness, the thickness of the glass to be processed and the actual temperature of the glass used Layer. The layer can usually by arranged therein cooling coils, through the cold Water flows, can be cooled, but it is also possible to regulate the quenching of the glass by the bed temperature with hot water or steam coils or with other heating devices is increased, and if gentle treatment is desired, this has been recognized as an advantage. When a glass that requires a curved shape of the glass is to be hardened, so will it first molded and then hardened in the same way as described.

The glass object or piece of glass must be substantially plate-shaped. It's understandable, that if the size of the object or piece of material is large, it will interfere with the fluidized bed works. The word “plate-shaped” should therefore be understood in this way in the description and in the claims be that thereby no restriction to a flat plate with a relatively large length and width and relatively thin thickness. Rather, it is supposed to be an object or a The piece whose thickness (i.e. that perpendicular to the vertical plane of introduction into the layer Dimensions or the horizontal dimension) is not sufficient to interfere with the fluidized bed act and prevent the cooling of the upper part or the surface of the object or piece. For example, long objects with a small cross section can be placed horizontally in the layer Success to be cooled. As another example, hollow thin-walled cylindrical objects such as Measuring glasses, successfully cooled with their longitudinal axes in a vertical position.

The invention is described in more detail using an exemplary embodiment shown in the drawing, namely shows

Fig. 1 is a side view of a device for hardening a glass plate,

Figure 2 is an end view of Figure 1 from the left. In Fig. 1, 1 designates the outline of a part of a furnace and 2 designates an overlaid rail on which a carriage 3 is movable. Tongs 4 in the manner of articulated tongs hang down from the carriage 3 and hold a glass 19. Below is a chamber 7 which contains a fluidized bed of sand, and this is by two lifting cylinders 8 in the raised position of chamber 9, which is shown in dashed lines Outline is shown, brought. A flexible tube 10 for air supply to the chamber? leads into a space 11 below a supported, ceramic air distribution plate 12, which is intended to cause the vortex movement of the sand layer in the chamber 7, which, as already mentioned, can be cooled by snakes la with water cooling. A guide 13 and guide rods 14 are provided for the chamber 7 in order to bring about a smooth lifting. An air supply 16 for raising the chamber and control valves 17 for raising and lowering the chamber 7 are shown. The glass 19 to be hardened is held by the tongs 4. The aforementioned oven doors 22 are also shown.

In FIG. 2, the edge of the glass 19, which hangs down from the joint pliers 4, can be seen. Chamber 7 and the lifting cylinders 8 are partly arranged in a recess 21 in the floor.

In an exemplary application of this method and apparatus, a glass plate measuring 1858 cm ² and nominally 0.635 cm thick was heated in the furnace, which was at a temperature of 720 ° C, for 320 seconds. It was then removed in the manner already described and cured in the manner described in the fluidized bed, which was essentially room temperature, for a period of 20 seconds. After releasing the pliers, it was allowed to cool to room temperature.

Obviously, the invention is not limited to having the glass emerge horizontally from the oven is taken out, as it is very possible to provide devices around the glass either lead out vertically upwards or downwards, although this is a somewhat different arrangement of the fluidized bed requires. Finely divided substances are used in the fluidized bed, for example metal powder, certain metal oxides, pumice stone ti. The like. Provided that they are obtained in the form of particles of a suitable size preferably between 100 and 200 microns in diameter, but advantageously sand particles are used. In order to ensure the homogeneous movement of the sand, it is preferred on a porous ceramic partition plate located near the bottom of the chamber and through which the air flows in sufficient quantity to ensure the movement of the sand, arranged. Of the The purpose of this type of partition is to create a distribution resistance for the air and thus an essentially homogeneous flow of the sand, but this distribution method can also by slag wool or felt or by a layer of pebbles, the size of which decreases towards the top, or in some other known manner.

Claims (6)

Patent claims: 1. A method for cooling glass plates, characterized in that they are in a layer of solid separate particles are brought while the layer is an upward gas stream exposed, the size and the Weight of the particles and the speed and type of flow is such that that of the The force exerted by the current is sufficient to counterbalance the force of gravity acting on the free particles and expand the layer to allow movement of the particles, but not sufficient to convert the layer into a particle stream. 2. The method according to claim 1, characterized in that particles of pebble sand be used. 3. The method according to claim 1 and 2, characterized in that particles with not less than 100 microns and no more than 200 microns in overall diameter can be used. 4. The method according to claim 1 to 3, characterized in that air is used as the gas stream will. 5. The method according to claim 1 to 4, characterized in that the gas flow through a porous ceramic partition plate is passed. 6. The method according to claim 1 to 5, characterized in that the layer is provided by in this Devices, for example pipe coils, in which a liquid or a gas circulated by the required temperature, is cooled. Considered publications:
VDI magazine, 1933, p. 617, paragraph 1. 1 sheet of drawings © 703 903/199 2.