Cutting glass on the Belyaevskaya branch
Cutting glass on the Belyaevskaya branch
According to the technology of grinding and polishing glass, it is necessary to establish the degree of roughness of the ground surface, since the duration of the polishing process depends on this. Surface roughness can be determined]: either by qualitative comparison tests or by quantitative measurement. In the first case, the quality of the ground surface is compared to the standard surface. This principle is based on the use of a microscope. comparator
Microscope. comparator “Comparax” has one eyepiece and a tube. It is designed to compare surface quality. The optical scheme of the microscope is shown at 97. The light beam of the low voltage lamp A falls on the translucent cube B, where it splits. One brush illuminates the test object and the other illuminates the sample being compared. The optical system of the microscope consists of an objective C and an eyepiece D and is sharpened to the plane of the observed and compared surfaces. By aiming both samples at the diaphragm £, one can simultaneously observe both surfaces in the eyepiece, of which the knzh fills half of the microscope field of view. Diopter sharpening is carried out by moving the eyepiece in the eyepiece tube. The dual illuminator allows for observation both in direct (perpendicular) light and at an angle of 45ft. Direct illumination is used for finely sanded surfaces, while side illumination is used for highly rough surfaces. An appropriate choice of eyepiece gives 12x and even 45x magnification. Comparative standards are embedded in a special clamp.
The optical device for measuring the surface roughness is a Schmalts-Linnik microscope; it is based on the principle of light section.
Cutting Stained Glass Pattern Pieces
Light from a low voltage source 1 passes through slit 2 into objective 3r, which casts a reduced sharpened image of the slit at an angle of 45 ° onto the measured surface 4. The observation tube is on the same plane as the illuminator, but the axes are at right angles. The straight beam, reflecting the slit in the visual field of the microscope, is deformed depending on the surface irregularities: in the eyepiece we observe a cross section at an angle of 45 ° between the veto strip and the measured surface. The observation tube, consisting of an objective 5 and an eyepiece micrometer 6, is actually a measuring microscope, with the help of which the depth and width of irregularities are determined. Double
a microscope manufactured by K. Zeiss, VHB, makes it possible to measure the depth of irregularities in the range of 0.5-50 microns. It was found experimentally that the maximum error of the microscope is ± (0.007 0.03 h), where h is the height of the measured profile in μ.
Contact profilometers measure the surface roughness with a high-sensitivity tip that slides over the measured surface, fixing all its irregularities. The movement of the tip is amplified and recorded by a special recording device. By setting up the profilometer, you can get data on the average roughness or a complete profile of the recording of the measured surface.
The most famous profilometers: English Telysurf, German Perth — o — Meter, Soviet Caliber and Czechoslovakian Somet; all tSjffclK ^ B ^ Ef ^.- i they are with a mastic compound. During operation, the movements of the measuring tip cause changes in the inductance, capacitance, or ohmic resistance of the bridge, which is supplied with a current with an alternating voltage. A high frequency voltage is applied to the microscope. These VEB K Zeiss Firms Disrupt Equilibrium
balanced bridge and a measuring voltage appears in its diagonal branch, which is transmitted to the amplifier.
The bridge is powered by the carrier voltage of generator A, the carrier frequency fluctuates between 5-15 kHz. The contact tip / is rigidly connected to the armature 2. The deflection of the tip turns the armature in the field of two coils 3 and 4 and thereby changes the inductance of both windings. With balanced bridges between B and C there is no voltage; the change in the inductance of the coils excites the measuring voltage Um, which is amplified by the amplifier D. The amplitude of the measuring voltage is proportional to the deflection of the tip; the frequency of the measuring voltage is the same, kick and carrier frequency. The same connection is provided for the bridge with variable capacitance and for the bridge with variable ohmic resistance.
Profile meter So met is available in two types: for workshop and laboratory measurements. The laboratory device consists of: the stage of the measuring head 2, the sensor Zu of the electronic part 4, the recording device 5, the integrator b and the working table 7.
The sensor unit consists of a cylindrical body, in which the induction device is located, and a sensitive tip. A four-sided diamond pyramid with an angle at the apex of 90 ° and a radius of curvature r = 3-r-P μ is used as a sensitive tip, which, together with the sensor arm, is located in a protective casing. The pressure of the measuring point on the surface is 0.1-0.15 g.
The laboratory device is equipped with two sensors: relative and absolute. The relative sensor has, at a certain distance in front of the measuring point, a support leg with a radius r —25 mm ^ which touches the tops of the irregularities, describing the envelope curve. This curve, when measured with a relative sensor, is the main one, to which all measured values of surface roughness are related.
The surface profile recorded by the profilometer is somewhat inaccurate, since no gentle undulating irregularities were recorded.
It is not recommended to measure rough surfaces with separate large projections with a relative sensor, which can distort the recording, especially with a very short measuring path. The relative sensor is supplied for both the “production” and for the laboratory device. Only the laboratory device is supplied with the absolute sensor. The absolute encoder does not have a reference foot, the unevenness recorded by the measuring tip is
To the path traversed by the shoulder “which at the maximum shift has a deviation of 0.3 microns from the ideal plane. Therefore, an absolute sensor can measure not only surface roughness, but also surface waviness or surface deviations from the ideal plane.
The measuring head consists of a guide, a motor driven by a sensor and a contact system for connecting an electrical circuit. A sensor is attached to the end wall of the guide, which makes a rectilinear movement in the horizontal plane equal to 50 mm. An asynchronous electric motor of about 24 e, placed in the head, has a gearbox, giving two speeds for graphic recordings and one for integration.
The electronic part is placed in the desktop and consists of a unit (power transformer with a converter) of an electric bridge generator and an electronic three-stage detector amplifier, an output stage for a recording device and an integrating stage.
A special device writes the profilogram in ink on registration paper 75 mm wide. The belt speed is regulated by the motor through the gearbox.
The integrator is essentially a damped magnetoelectric galvanometer that records the arithmetic mean deviation from the mean mowing line Rfl. The integration speed is adjusted by means of a gearbox placed in the measuring head, the integration path can be 1.8 or 3.6 mm. The total sensor path is then 2.5 or 5.0 mm. Integration values RfI can be measured in two ranges: for an irregularity pitch less than 0.4 mm and an irregularity pitch less than 0.1 mm. If the pitch of the unevenness is more than 0.4 mm. then the value of Ra must be calculated from the profilogram and the height of the unevenness Rz based on the ratio: lgRz:: 0.65 0.97
Both types of Somet profilers provide a vertical magnification of 200-50,000 in eight ranges and a horizontal magnification of 50-400 in four ranges. When using a relative sensor, the support leg eliminates the effects of ambient vibration and shock, “allowing you to work at maximum vertical magnification. An absolute encoder, on the other hand, is extremely sensitive to all external impulses, so measurements can only be taken at magnifications up to 10,000.
To measure curved surfaces, an additional radius device is used, which can be attached to the measuring voice of the device. The object to be measured is fixed on the stage so that when the sensors move, it remains stationary, and after sufficient heating of the electronic part of the profilometer, the required vertical and horizontal magnification is set. The choice of vertical magnification depends on the surface roughness; for a certain surface, the increase can be adjusted to the desi of the maximum, at which the graphic record will occupy two-thirds of the registration paper.
The surface to be measured must be thoroughly cleaned, the tip of the sensor is installed on it, the length of the measured section is determined, the recording device and the motor are switched off. The measuring tip begins to move along the measured surface, noting all its irregularities; the electronic device transmits all vibrations of the tip to the recording device, which traces the surface profile curve on the registration paper mite.
When processing the profilogram, first of all, the average line M is determined. This straight line, passing within the measured sections through the entire geometric profile, divides its teak so that the sum of the squares of the profile deviations from the average mowing line is minimal. The maximum roughness height Rm can be determined with a medium mowing line: GRINDING AND POLISHING GLASS
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