SU906952A1 - Method and apparatus for tempering glass - Google Patents

Description

H3o6peteHHe relates to industry, to carry building materials, namely glass hardening by liquid quenching and can be used in the glass industry to obtain high-strength glassware.

A known method of liquid tempering glass, the advantage of which is an increase in the degree of tempering glass, which is achieved by increasing the intensity of cooling Cl.

However, with an increase in the intensity of cooling, thermal and elastic stresses arise in glass, leading to the formation of microcracks and scratches. These microcracks and tears reduce the strength of glass, for example, for intensely tempered glass, equality is not observed.

1 PC5 + FC5 "

where PQ and PJ are the strengths of the original and tempered glass.

 surface stresses.

In addition, they are a source of spontaneous destruction of hardened glassware. Of particular danger are microcracks and checks that form at the leading edge of glassware, since its intensity of cooling is much higher than the intensity of cooling of subsequent parts.

Thus, with an increase in the intensity of glass cooling, the contradiction between the processes of the formation of quenching and thermoelastic stresses increases. On the one hand, intensive cooling contributes to an increase in the degree of hardening, but on the other hand, the microcracks formed at the same time and along the chop reduce the E (|) hardening effect,

The closest in technical essence and the achieved result is the method according to which the leading edge of the glass is heated (predominantly) higher than the slave one, after which it is cooled by immersion in a uniformly heated liquid. A device for implementing a known method comprises a preheating furnace, a tempering furnace with a mechanism for moving glass and a cooling bath with a liquid. The leading edge of the glass is heated above the slave due to the uneven movement of the glass through the heating zone of the quenching furnace so that the leading edge is longer in this zone than the slave 23. The disadvantages of this method include the fact that finding the leading edge of the glass in the heating zone longer time than the time of the slab edge, leads to deformation of the product. At the same time, the cooling of the glass, the leading edge of which is heated C above the driven side by immersion in a liquid uniformly heated to a relatively low temperature (for example), does not completely exclude the formation of gaps on the leading edge of the glassy part, and the increase in the temperature of heating the liquid decreases the degree hardening, t, e. eliminate the contradiction between the processes of formation of quenching and terms of elastic stresses using a known method is not possible. In addition, the implementation of the principle of creating a temperature gradient over glass by moving it through the heating zone of a quenching furnace leads to an increase in the dimensions of the tempering furnace, to unjustified power consumption, and also encounters serious technical difficulties associated with the need to ensure an uneven movement speed, which is determined Not only heat is the physical properties of glass, but also the geometric dimensions of glassware. The aim of the invention is to increase the degree of strengthening and the quality of glass. but. The goal is achieved by the method of quenching, which includes heating the glass to ensure the leading edge temperature is higher, moving and cooling 24 in a liquid, the leading edge of the glass is heated 10-50 ° C higher than the slave, and the upper layers with a thickness of cm are heated by 50- 20 ° C above the rest. In this case, it is advisable to carry out heating with a temperature gradient from bottom to top. In addition, the glass is cooled with exposure to a liquid at 10-50 ° C for 30-60 minutes. In the glass quenching device, which includes a preheating furnace, a tempering furnace with heater elements, a cooling bath and a glass transfer mechanism, the tempering furnace is rotatably mounted 180, with a free fall rate of glass and equipped with Guides and a clamp, and heating elements They are located along its height with decreasing steps upward, the cooling bath is equipped with heaters in the upper part and refrigerators in the lower part, and the movement mechanism is designed as a monorail, with electric and and automatic capture. The drawing shows a device for quenching glass, a general view. The device contains a furnace. 1 is a preliminary heating unit, which is a heat-insulating chamber with heaters for heating glass to 00-500 ° C, mounted on an electric fuse 2 suspended from a monorail and equipped with an automatic gripper k. Below the furnace 1 is installed on a driven carriage 5, a cooling bath 6, equipped with heating elements 7, which provide heating of the upper liquid layer 5-15 cm thick to 250 C (cooling zone) -, cooler 8, ensuring that the temperature of the rest of the liquid (quenching zone) is maintained at 10-50 ° C, with fins 9 to prevent mixing of the liquid and the shock-absorbing bottom 10. Between the furnace 1 and the bath 6 with the liquid, a hardening furnace 13 is placed on the pins 11 provided with a rotary drive 12 with the free fall rate of glassware which is a heat insulating chamber with heating elements Ik arranged in increments leading upward, guides 15 and a clamp 16 for glass. The second automatic grip 18 is suspended to the monorail 2 by means of another electric hoist 17. A loading conveyor 19 and a loading conveyor are located on either side of the bath 6 (not shown). The operation of all elements of the plant is automated through a single technological cycle and consists in the following. The glassware from the charging conveyor 19 is removed by automatic gripping and enters the preheating furnace 1. The electric heaters with a horizontal displacement drive (electric hoist) of this furnace are turned on and the latter is installed above the quenching furnace 13. After the desired heating temperature CiOO-SOO C) The guide 15 is previously removed to the quenching furnace mode 13 and is fixed by the latch 16. Next, the glass is maintained at the rate of 40-60.s. per 1 mm thickness and the furnace 13 by means of its own Water 12 is rotated in free rotation rate. At the end of the turn, the latch 16 is turned off and the glass falls into the cooling bath 6, in which the upper layers of the liquid are heated 100-200 ° C above the lower ones. Then the furnaces 1 and 13 return to their original position, and a new glassware enters the furnace 13. After 30–60 minutes of holding the glass in the bath 6, the drive of the trolley 5 moves and the bath 6 moves to the unloading position, where the glass is removed from the bath by the automatic gripper 18. Next, the bath 6 returns to its original position and the gripper 18 attached to the electric 17 moves the glass to the unloading vessel. The use of the proposed quenching method and device for its implementation provides, by comparison with the known method and device, the creation of a temperature gradient in glass, located in a vertical position, in which the more heated edge is at the top, which allows to increase its heating temperature by 5-10 ° C higher than; with the existing method without increasing the degree of deformation of the glass. At the same time, the vertical position of the glass and its rotation by 180 ° with the speed of free fall, unlike its movement through the heating zone of the quenching furnace, practically does not reflect on the deformation of the glassware. In addition, the cooling of the glass, the leading edge of which is heated 1050С above the slave, in a liquid whose upper layers are heated 50-200 С higher than the rest, makes it possible not only to almost completely eliminate the formation of nicks and microcracks, but also to increase the degree of hardening. This is achieved by reducing the intensity of cooling of the leading edge of glassware at the first stage of its immersion in a liquid, i.e. at the moment of contact with the liquid and the increase in the intensity of cooling in the second stage of immersion, i.e. when glassware is completely immersed in a liquid. PRI me R 1. 100 samples of 100x100x5 mm in size with polished ends, made of industrial sheet glass (Bor Glassworks) are arbitrarily divided into 10 batches. The first three batches are quenched according to a known method, and the remaining seven batches according to the proposed method. Polymethyl siloxane fluid RMC-tOO is used as cooling medium. When tempering the glass according to the proposed method, the thickness of the heated part of the liquid is cm, the quenching zones are cm (the total height of the liquid is 20 cm) and the dwell time of the glass in the liquid quenching zone is 30 minutes. Hardened samples are subjected to visual inspection for the presence of scratches and the determination of the mechanical strength of the central symmetric bending. The strength of the original glass is 2 mg / mm with a coefficient of variation of 33%. Table 1 shows the experimental data obtained.

Table 1

From Table 1 it can be seen that when glass is quenched in a known manner, with increasing temperature of the liquid heating, the likelihood of nick marks actually decreases, but at the same time the degree of strengthening of the glass decreases. This indicates that the well-known method of glass hardening does not completely resolve the contradiction between the processes of the formation of quenching and terms of su-elastic stresses. The proposed method of glass quenching provides an increase in mechanical strength with a simultaneous decrease in the probability of forming gaps at the leading edge of the glass. It can be seen that if during the tempering of glass in a known manner, 6 out of 30 samples had checks, i.e. 20, when tempering glass by the proposed method, only 3 out of 70 samples, i.e. k%. In addition, the proposed method of tempering glass provides tempered glass with significantly more stable mechanical properties, which is of particular practical importance. Thus, the safe level of strength of glass tempered in a known manner does not exceed 0.3 mg / mm, while the proposed method provides obtaining glass, the safe level of strength of which exceeds 10 kg / mm; EXAMPLE 2. Four batches of samples (5 samples in each batch) are tempered as in Example 1, with the only difference that the holding time the glasses in the quenching zone of the liquid vary from 5 to 120 minutes. Continuous heat removal is provided by adjusting the flow rate of the water through the refrigerator of the liquid bath. Conditions, quenching, strength of quenched specimens, as well as values, values relative to the increase in strength R (Pj-Po) lOO / P

9906952

where RP and P.

have the indicated meanings.

From Table 2 it can be seen that an increase in the glass exposure in the quenching zone of the liquid under conditions of continuous heat removal from 5 to 60 minutes results in a strength of approximately 3kg / mm, which is. A further increase in the exposure time does not significantly affect the strength.

Claims (3)

1. A method of tempering glass, including heating the glass to ensure the temperature of the leading edge is higher than the slave, moving and cooling in a liquid, characterized in that, in order to increase the degree of strengthening and quality of the glass, the leading edge of the glass is heated 10-50 ° C higher than the slave, cm thick upper layers are heated 50–200 ° C above the rest. 2. Method pop. 1, distinguished by the fact that, in order to reduce the degree of deformation of the glass, the heating is carried out at a temperature gradient from bottom to top. ten Table 2 shows the strength of the original and tempered glass. table 2 3. The method according to paragraphs. 1 and 2, about the fact that the glass is cooled with exposure to a liquid at 10-50 ° C for 30-60 minutes. . k. A glass tempering device including a preheating furnace, a tempering furnace with heating elements, a cooling bath and a glass movement mechanism, characterized in that the tempering furnace is rotatably mounted at free fall speed of the glass and provided with guides and a lock the elements are located along its height with decreasing pitch, the cooling bath is equipped with heaters in the upper part and refrigerators in the lower part, and the movement mechanism is designed as a monorail with electric and automatic grabs. Sources of information ° taken into account in the examination 1. Bartenev G.M. Mechanical properties and heat treatment of glass. M., I960, p. 121-129. 2. The patent of Great Britain No. 1253681, 1 M, 1976 (prototype).