SU785244A1 - Method of quality control of sheet glass tempering - Google Patents

Description

The invention relates to the manufacture of glass. And can be used to control the quality of the tempering of glass samples, and glassware. A known method for controlling the quality of tempering glass is based on measuring the quenching stresses in glass by the difference in the course of the rays in polarized light fl. However, this method allows one to determine the stresses only in the middle layers of a glass sample, while the quality of quenching is determined by the magnitude of the stresses in the surface layers. A known method of controlling the quality of sheet hardening, glass, including one-sided etching of the console. In this method, the deformation of the glass sample caused by the imbalance of residual stresses when removing the surface layer is measured, and the stresses are determined from each layer removed, depending on the physical properties and geometric dimensions of the glass sample. . . The disadvantage of this method is low accuracy, due to the large error in measuring the true thickness of the removed sample layers. In this method, the sample thickness is measured by a lever system with floating probes. However, due to the chemical heterogeneity of the glass, its surface is unevenly etched and the etching surface has a spongy morphology. Under these conditions, direct measurement of the sample thickness even at several points does not characterize its actual thickness, and averaging the thickness according to the results of discrete measurements gives a large error. The aim of the invention is to improve the accuracy of control. This is achieved by the fact that in the method of controlling the quality of a flat glass pin, including one-sided etching of a cantilever. glasses, additionally determine the rate of glass deformation caused by imbalance of residual stresses when removing the surface layer, and the rate of glass etching, compare them and judge the quenching quality of the glass by the ratio of the strain rate and etching rate. The method is as follows. With continuous etching of the sample, there is a constant change in the surface morphology. Convexities and hollows continuously appear and sweep over the entire plane of the sample. Thanks to this operation, the etching rate of the image etching allows to obtain much more objective data on the dynamics of the process of removing layers and gives fairly accurate information about the thickness averaged over the sample area. In this case, the process of imbalance of the residual stresses, accompanied by continuous deformation of the sample, is characterized by the rate of change of the bed in time. The ratio of the deformation rate and the etching rate allows us to judge the quality of hardening.

The drawing shows a functional diagram of the method.

The method is implemented as follows. A sample of tempered glass 1 is clamped to a bath 3 with herbal reagent 4, such as a 20% hydrofluoric acid solution, with the help of a clamp 2, so that the bottom side of the sample is in contact with the solution over its entire plane. This begins the process of etching the surface layer. In order for the etching to be carried out only on the surface, the lateral ends of the glass 1 can be coated with wax.

When etched due to an imbalance of the residual stresses, the glass sample begins to bend upwards. However, due to the effect of surface tension forces, the immediate contact of the etching agent and the glass surface is not disturbed and etching continues.

If, as the sample is etched, the deflection reaches such a value that there is a danger of rupture between the surfaces of the sample and the pickling reagent (greater residual stress), then the solution level in the bath will be increased. The rate of deformation of the glass sample is directly proportional to the magnitude of the stresses in the removal of the layers and the etching rate (thinning rate) of the glass. Speed trawling

is determined by block 5 for determining the etching rate depending on information from the temperature sensor 6, the concentration sensor 7 for the etching reagent and the setting unit 8 for the glass. The strain rate is controlled by the strain gauge 9 and the differentiator 10. Computing unit 11 divides the signal of the differentiator 10, which carries information about the sample deflection rate, by the block 5 signal, which carries information about the etching rate, and scaled the result according to physical properties glass (Punch coefficient, modulus

5 elasticity) and the initial geometric dimensions of the sample (length, width, thickness). The recorder 12 records the output signal of the computing unit 11 proportional to the distribution of stresses over the sample thickness. The quality of quenching of the sample is determined depending on the distribution of stresses across its thickness, recorded by the recorder 12.

Claims (2)

Invention Formula The method of quality control of sheet glass quenching, including one-sided etching of cantilevered glass, characterized in that, in order to increase the control accuracy, the glass deformation rate caused by imbalance of residual stresses during removal of the surface layer and the glass etching rate are compared and compared to based on the ratio of the strain rate and the etching rate 0, judging the quality of glass tempering. Sources of information taken into account in the examination 5 1 USSR author's certificate J 104658, cl. From 03 to 27 / QO, 1962 .. 2. USSR author's certificate 242466, cl. C 03 B.27 / 00, 1970 (prototype). If I / I f J 4 S - 7