FI89583C - Foerfarande och anordning Foer maetning av boejningsgraden hos en glasskiva - Google Patents

Description

1 89583

Method and apparatus for initiating the degree of bending of a glass sheet. -Forward and anordning for mâtning av bojningsgraden hos en glasskiva.

The invention relates to a method for measuring the degree of bending of a glass sheet using an optical measuring unit for applying a light rain on the surface of a glass sheet and a measuring rain crossing the light rain on the one hand. The invention also relates to a device for initiating the degree of bending of a glass sheet. the apparatus comprising an optical measuring unit having first optical means for transmitting the light beam and second optical means for receiving and directing the measuring rain crossing the light rain to the light detector.

A laser-assisted method and device for measuring the degree of bending of this type is disclosed in the applicant's earlier Finnish patent application 912871. It is proposed to use a measuring device known per se based on CCD camera technology so that the degree of deflection of glass can be monitored with a fixed device. However, a measuring device based on CCD camera technology is relatively expensive because a large number of sensitive light detectors are required. The positioning of such a device for various applications also requires great precision.

The object of the invention is to provide an improved method and device which can be drilled into a simpler and cheaper Laitrr construction, which can then be advantageously used for both the measurement of bending and the control of bending. - ·. and after possible hardening.

The object of the invention is achieved in the appended claims. ; on the basis of the characteristics set out in

In the following, one embodiment of the invention will be described in more detail 2,89583 with reference to the accompanying drawings, in which Fig. 1 shows a schematic side view of the general structure of a measuring device according to the invention; Fig. 2 schematically shows the construction of an optical scale included in the device; Fig. 3 shows a cross-section of optical means for transmitting a light rain 4 (e.g. a laser beam); Fig. 4 shows a cross-section of the optical members for receiving the measuring rain 5; and Fig. 5 shows on an enlarged scale the use of a boundary line 16 provided with a rectangular slot 17 in front of the light emitting diode 15.

The device consists of three main components, which are the optical measuring unit 1, the actuating mechanism 2 of the measuring unit and the electronic measuring and control means 3 controlling the operation.

The degree of bending of the surface 20 of the glass sheet is monitored by measuring its distance by means of two intersecting optical staples 4 and 5. The second rainfall is a light rain 4 formed by means of a laser and optics 6, which forms a small illuminated area on the surface of the glass to be examined, with a diameter of 300 to 500. At point 21, a measuring rain 5 intersects with the light rain 4 at a fixed preselected deflection, by means of which the light reflected from the object is collected in a detector, which in the case shown is a light emitting diode 15 in the optical tube 7 (cf. Fig. 4). The optics 7 and the detector 15 together form or define a measuring rain 5. The measuring rain 5 can thus be defined as a volume in which a light source (point 21) 3 8958ό can be detected by the detector 15 connected to the optics 7 only and only if the light source (point 21) is located in said volume. It is clear that the LED is not the only detector in question and that there may be several detectors in the same device. The measuring radius 5 is delimited by a rectangular slot 17 of the delimiter 16 so that it is rectangular on the surface 20 of the object, the dimensions of which are e.g. 0.3 x 5 mrn ^. The rectangular shape achieves good measurement accuracy and avoids the orientation problems that would result from applying two small rains to the same point. The precipitation can be delimited by several different methods and the shape does not have to be rectangular, but can usually be elongated. Alternatively, the lighting rain 4 can be limited to an elongated shape. Trimming facilitates the manufacturing tolerances and use of the device, but is not essential to the operation or accuracy of the device.

The measurement of the distance of the object surface 20 is based on the fact that light reflection from the light rain 4 to the measuring beam 5 is only possible if the object to be measured is exactly at the intersection 21 of the two rains 4, 5. There is thus an optical triangulation method with rain intersection 21 measurement of the triangle.

According to Figure 3, the lenses 11 and 12 of the laser optics 6 are fixed; attached to the tubular body 13 to which the laser 10 is also attached.

-j- According to Figure 4, the limiter 16, the lens 18 and the filter 19 of the light emitting diode 7 are attached to a tube 14 to which the light emitting diode 15 is also attached behind the limiter 16.

. . As can be seen in Fig. 2, both tubular optical members 6 and 7 are fixed to the body 9, whereby they form a unitary movable optical measuring unit 1. The selection distance of the starting points of the measuring paths 4 and 5 can be, for example, 30 cm.

4,89583

However, it, as well as the angle between rains 4 and 5, can be preset to some fixed value.

In general, the method according to the invention is based on the fact that the position of the optical probe 1 complains about the degree of bending of the glass plate and the actuator 2 or the user of the measuring device tends to keep the optical probe 1 at or near constant distance from the glass plate 20 by said optical triangulation.

The light emitting diode 15 is connected, by selection of the amplifying electronics part 8, to the measuring and control means 3, which control the mechanism 2 by means of which the optical measuring unit can be moved back and forth vertically. Thus, the measuring and control means 3 on the one hand control the movement mechanism 2 and on the other hand monitor the electrical signal coming from the light emitting diode 15. A possible solution for Eras as a measuring and control line is a programmable logic with analog inputs and outputs, in which it is possible to program the required search strategy for the target 20.

Linear motors based on a direct current or stepper motor can be used as the actuating elements 2. In principle, both are equally suitable for the purpose, but DC linear motors with a position or position measuring potentiometer are the simplest to control and more inexpensive. The measuring and control means 3 thus have information on the position or travel of the optical measuring unit 1 with respect to a preset value, which is e.g. selected so that the intersection point 21 is located at the surface 20 of the glass sheet bent to the desired degree. This information about the position or travel can thus be complained about from a sensor associated with the actuating means 2 or can be obtained directly from the control steps provided by the control means 3 (e.g. when using a stepper motor). The degree of bending can be monitored continuously as the glass bends by lowering the optical measuring unit 1 so that the intersection of the rains 21 5 89583 follows the surface 20 of the glass. The measurement result is reported as ± a deviation from a predetermined target value. For verification measurements, a statement as to whether the measurement result is within acceptable limits is sufficient.

Claims (6)

A method for measuring the degree of curvature of a glass slab by tamping optical triangular measurement, in which the surface of the glass slab (20) on one side is directed a light beam (4) and on the other, a light beam crossing food beam (5), while said beams optical means (6, 7) are placed in an optical measuring head (1) at a distance from one another, the intersection point (21) of said beams (4, 5) and said optical means (6, 7) forming a measuring triangle, characterized by , that the position of the optical measuring head (1) conveys information about the degree of diffraction of the glass disk and, by means of a stirring mechanism (2), strives to keep the optical measuring head (1) at a constant distance or approximately at a constant distance from the glass plate (20). said optical triangle supply, for which purpose the motion measuring mechanism (2) of the optical measuring head (1) is controlled by electrical measuring and control means (3), which simultaneously observes the electrical detector (15) coming from said measuring beam (5) signal. 2. A method according to claim 1, characterized in that a laser beam is used as a light beam (4). A device for measuring the degree of curvature of a glass sheet, said device comprising an optical measuring unit (1), which has an optical means (6) for receiving such a light beam (4) and other optical means (7) for receiving and directing a light beam crossing measuring beam (5) to a light detector (15), characterized in that the optical measuring unit (1) is arranged to be moved by a motion mechanism (2), which is controlled by electrical power, control means (3) with information on the motion unit or layer of the measuring unit (1) and which control means (3) additionally observe the electrical signal coming from said light detector (15). 9 39583 4. Apparatus according to claim 3, characterized in that said understanding or other optical means (6 or 7) comprise a cutter (16), whereby the light beam (4) or the food beam (5) is made in cut-off elongation, e.g. rectangular shaped. Device according to claim 3 or 4, characterized in that the light detector (15) is a photodiode. 6. Apparatus according to claim 3 or 4, characterized in that the optical measuring unit (1) is vertically movable back and forth linearly.