RU2694119C1 - Device and method for monitoring resistance strain gauge gluing quality - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to the field of measuring equipment, namely to strain-gauge measurement of objects deformation, and is intended for checking the quality of gluing resistance strain gauges (RSG) on products from any materials. Device comprises verifiable RSG 13, attached to strain gauge object 12, a resistor, a power supply, an amplifier connected to the band-pass filter, an internal half-bridge, intrinsically safe barriers, as well as a loading RSG appliance. A spring-loaded rod 4 is installed in the housing of the device; on one side the rod is fixed with cover 5 of the housing, on the other side it protrudes beyond the limits of the housing and is equipped with nozzle 6 with tip 7 of sticky material. Device comprises limiter in form of vertical plate 11, one part of which is fixed on housing, and other rests on object of strain gauge, rod is installed so that tip 7 is in contact with RSG, and with the possibility of displacement to the distance limited by the spring movement.

EFFECT: technical result consists in improvement of accuracy of determination of quality of adhesion of RSG on any materials.

2 cl, 6 dwg

Description

The group of inventions relates to the field of measurement technology, namely, to strain measurements of the deformation of objects and is intended to check the quality of gluing of resistance strain gages (TP) on products made from any materials.

In those areas where products, including those made from explosive materials (VM), are subjected to significant loads, deformations, their technical characteristics are investigated. Strain gauging - one of the types of measurements in research. The quality of the strain measurement, the quality and reliability of the studies performed depend on the quality of gluing of the strain gages.

A device for determining the quality of gluing strain gauges on paper and film basis (a.c. RF №620806, IPC G01B 7/16, publ. 1978), consisting of: a current source, the outputs of which connect the TP, thermal receiver, moved along TP surface to determine the zone of greatest overheating; DC amplifier to amplify the signal from the thermal receiver; a voltmeter, to the output of which the amplifier is connected. This device has the following disadvantages: the thermal conductivity of the material of the object will have a significant effect on the readings of the voltmeter, as a result of which this device can be used only on metals; thickness, uniformity, thermal conductivity of the adhesive layer, ambient temperature will also affect the final result; in view of the above, the probability to identify a poorly glued TP using this device is significantly reduced.

The closest analogue of the quality control device for sticking TP in the group of inventions, which is taken as a prototype, is a device containing a verifiable TP, glued to the strain gauge object, a resistor, a power source, an amplifier connected to a band-pass filter, and an internal half-bridge (RF No. 2086912 , IPC G01B 7/16, published in 1997). The device also contains a model TP, which together with the test forms an external half-bridge; additional resistor, modular bridge balancing device; a device for balancing the bridge in phase; DC carrier generator; alternator carrier alternator; node summation bearing; electronic key; DC test current generator; trigger pulse generator; low pass filter; DC amplifier; low pass filter; bridge balance indicator by module; bridge balance indicator; attenuator; comparator reference signal generator; comparator; logic block; first and second electro-optical indicators.

The outer half-bridge consists of series-connected TP taken from the same TP batch of the TP being inspected and model TP. The checked TP is pasted on the object of strain gauging: the quality of gluing of exactly this TP is checked. Exemplary TP should be pasted on a test beam of the same material as the object of strain gauging with the same adhesive and using the same technology as the tested TP; The test beam is subjected to mechanical tests to determine the quality of sticking to it TP, which, according to the results of mechanical tests, should be considered satisfactory.

The internal half bridge consists of two series-connected resistors of the same resistance. The shoulder resistances of this half bridge are chosen to be no less than 50 times the resistance of the shoulders of the outer half bridge. This is necessary so that the test overheating of the internal half-bridge would be negligible compared to the test overheating of the TP of the external half-bridge. The outer and inner half bridges are connected in parallel and together form a four-shouldered measuring bridge.

This device provides a sufficiently high accuracy of TP sticking quality control by expressly obtaining information on whether the sticking quality of the tested TP from the sticking quality of the standard TP is within the allowable limits.

However, this device can not be used to study the objects of strain gauges made of plastic, explosive materials: checking the quality of gluing requires the presence of a reference glued TP (model). The process of obtaining information about the strain gauge is more time consuming: it requires the construction of a graph, comparing it with the graph obtained on a model TR. Due to the impossibility of obtaining an absolutely identical TP (exemplary), low accuracy of sticking quality checks is possible.

There are known methods for monitoring the quality of sticking of TP, which use parameters that are indirectly related to the quality of the label, which can be influenced by non-informative functions of existing physical quantities: temperature, electrical noise, thermal conductivity, adhesive thickness, etc. At the same time, all known technical solutions use the following indicators to monitor the quality of sticking of TP:

- control of the temperature of the outer surface of the TP by passing an electric current through it using a point thermal receiver touching the outer surface of the TP connected via an amplifier to a voltmeter (AS RF No.620806, IPC G01B 7/16, published 1978);

- characteristics obtained with a short-term pulsed heating current passed through TP related to the shape and amplitude of the response in the measuring channel, for example, the duration of its front and rear edges, changes in the decay time of the pulse shelf, the presence of electrical hysteresis, and comparing it with the control parameters TP (AS of the Russian Federation No. 724919, IPC G01B 7/18, publ. 1980). The method is mainly applied to metals and a limited number of TP ratings;

- the capacity between the TP and the metal test object in comparison with the control TP - the smaller the capacity, the worse the pasted TP (AS RF No. 1657945, IPC G01B 7/18, publ. 1991).

Also used: insulation resistance TP in comparison with the control TP (the lower the resistance, the worse the pasted TP); temperature change in places of non-glue, leading to the appearance of stains of the indicator heat-sensitive paint, previously applied to TP, when the latter is heated by electric current; change in the resistance of TP from vacuum exposure (the method is not suitable for TP having defects in the form of leaky air spaces, the air from which can be evacuated during vacuum).

The closest method of the same purpose to the claimed method in the group of inventions is the method of quality control of gluing resistance strain gages, which means that the glued TP is loaded and, by changing its resistance, gluing quality is judged (AS RF No. 1180682, IPC G01B 7/18 , published in 1985). In this case, the loading is carried out by evacuation. A construction element with glued TP is placed in a vacuum chamber, TP is connected to a recording device, vacuum chamber. In the places of low-quality sticker TP there is an air gap in which an overpressure occurs when evacuating. The latter deforms the wire grid TP, while changing its resistance, which is fixed by the recording device. According to the magnitude of the change in resistance, the quality of sticking is judged; the greater the change in resistance of TP, the more unattached sections, i.e. the greater the number of air bubbles.

This method allows, with minimal time, to carry out quality control of sticking to TP of any type, with different heat resistance and different geometric dimensions.

However, this method has several disadvantages: often the object of strain gauging has such large dimensions that it is not possible to place it in a vacuum chamber; not all strain gauging objects can be evacuated, in particular, containing VMs; for the correct operation of the method, a complete tightness of the glued strain gauge is necessary (ideal case), otherwise when exposed to a vacuum, an air bubble through non-glued channels will also leave the strain gauge under the influence of a vacuum.

It should be understood that the quality (ideally) pasted TP is the one whose sensitivity corresponds to the passport value (that is, when the decrease in the sensitivity of TP is zero percent).

Thus, all known methods use for control only indirect parameters, on this basis it can be “guaranteed” to state that their accuracy is low, i.e. they will definitely lose to the proposed method in accuracy. In addition, the known technical solutions are not suitable for all types of materials (for example, explosives), since they have no barriers, are spark-proof, work with currents and voltages that are inadmissible for explosive materials, and require the presence of simulators, which is contrary to the rules of explosion safety.

A single technical result obtained when using the proposed group of inventions is to improve the accuracy of determining the quality of gluing TP on any materials.

This technical result in the implementation of the group of inventions on the object - the control device is achieved by the fact that the device containing the tested TP, glued to the object of strain measurement, a resistor, a power source, an amplifier connected to a band-pass filter, and the internal half-bridge, according to the invention, are equipped with artificial protection barriers, digital oscilloscope, personal computer (PC) and device for loading TP, in the case of which a spring-loaded rod is installed, on one side of the rod is fixed roofs The body, on the other hand, protrudes beyond the body and is provided with a nozzle with a tip made of sticky material. A sleeve is installed in the body, between which and the lid is a spring, the fixture contains a stopper in the form of a vertical plate, one part of which is fixed to the body, and the other rests on the object of strain measurement, the rod is installed so that the tip is in contact with TP, and with the ability to move a distance, limited by the movement of the spring, the power source is connected to the first barrier rozaschity, half bridge midpoint, TP formed with a resistor, coupled to the second barrier iskrozashchity which is connected to an alternating current amplifier, a bandpass filter connected to a digital oscilloscope, connected to the PC.

This technical result in the implementation of the group of inventions on the object - the method of quality control of sticking TP is achieved by the fact that the method consisting in the fact that the glued TP is loaded and by changing its resistance is judged on the quality of sticking, the special feature is that TP is loaded with a device through the tip several cycles of alternating effort with a frequency of up to 10 Hz and register the change in resistance of the TP.

Creating a device as described above, in which the non-glued portion of TP (if present) has a direct mechanical effect for several cycles to achieve a stable response (as a result of which the resistance of TP significantly changes), improves the accuracy of determining the quality of adhesion of TP without disturbing its quality. sticking. At the same time, the presence of spark barriers and the ability of the device to operate under normal conditions (without providing high currents, voltages, temperatures to the test object) significantly expands the scope of the present invention for all types of materials, the impact on TP is constant in size due to the limited course rod in the device for loading TR.

The claimed inventions are interrelated so that they form a single inventive concept. Indeed, when creating a quality control method for sticking TP, a new TP quality sticking device was invented. Using this device allows you to get the desired technical result - to improve the accuracy of determining the quality of gluing TP on any materials.

When analyzing the level of technology is not detected analogues, characterized by signs that are identical to all the essential features of this invention. And also not revealed the fact of fame of the influence of the signs included in the formula, on the technical result of the proposed technical solution. Therefore, the claimed invention meets the conditions of "novelty" and "inventive step".

FIG. 1 shows the scheme of the claimed control device.

FIG. 2 shows a device for creating a load.

FIG. 3 shows the initial state of the TP loading device (adhesive material is in contact with TP).

FIG. 4 shows the loading TP.

FIG. 5 shows the loading TP in the opposite direction (unloading).

FIG. 6 shows the response waveform.

A quality control device for sticking TP, which implements the inventive method, consists of a device 1 for creating a load and a measuring channel 2 (Fig. 1, 2).

The device 1 includes a housing 3 in which a spring-loaded rod 4 is installed. On the one hand, the rod is fixed by a cover 5 of the case, on the other hand it protrudes beyond the limits of the case and is provided with a nozzle 6 with a tip 7 made of sticky material in the form of a cone. The housing contains: a centering bushing 8, a bushing 9, a spring 10. A spring 10 is located between the bushing 9 and a cover 5. The fixture 1 also contains a stopper in the form of a vertical plate 11, one part of which is fixed to the casing 3 and the other is supported by a strain gauge 12 to which TP 13 is glued. The rod 4 is mounted for movement over a distance limited by the movement of the spring. The adhesive material is molded by hand before checking the TP sticker and installed on the nozzle. In the initial state, the adhesive material is in contact with TP (Fig. 3). At the same time, the lowermost (initial) position of the tip must be adjusted so that there is a distance between the nozzle and TP, ensuring the transfer of force only through the tip 7. After checking TP, the tip is manually reinstated to the tip.

Measuring channel 2 contains a resistor 14, a power source 15, an AC amplifier 16 connected to a band-pass filter 17, barriers of spark protection 18.19, a digital oscilloscope 20, PC 21. Power source 15 is connected to the first barrier of spark protection 18, midpoint C half-bridge, formed by TP 13 with a resistor 14, is connected to the second barrier of spark protection 19, which is connected to an AC amplifier 16. Band-pass filter 17 is connected to a digital oscilloscope 20 connected to PC21.

The method is as follows.

Pressing the cover 5 until the stop moves the rod 4, which causes the deformation of the tip 7, thus, the load TP is (Fig. 4). The loading on TP is determined by the force of compression of the spring acting through the sticky material and the distance between the nozzle and the TP. At the same time TP is subject to tensile deformation in the places of its non-gluing.

When the cover is released, the spring 10 expands, dragging the rod in the opposite direction (Fig. 5). The rod 4, rising up, carries the tip 7 behind itself, loading TP 13 in the opposite direction. TP loading in the opposite direction is proportional to the spring stiffness and elasticity of the sticky material.

With a high-quality sticker, the TP sticking out from the test object and the tip completely sticking out from the TP does not occur. With poor-quality sticker, the presence of air bubbles, sticky tip material can even tear the TP from the test object.

After several cycles of loading: pressing and releasing the cover, about 5-10 times within 3-5 seconds, there is a change in resistance TP that is synchronous with the loading, the magnitude of the amplitude of which determines the quality of gluing of the TP. At the output of measuring channel 2, a time response is recorded — an oscillogram in the form of a voltage curve. Due to the fact that pressing the cover in the device is carried out in manual mode, the maximum possible attainable frequency of exposure to TP will be no more than 10 Hz.

The greater the change in resistance (or the larger in amplitude the voltage response in the measuring channel), the worse the TP is glued. FIG. 6 shows the results of resistance measurements: curve a — ideally glued TP, curve b — poorly glued TP.

When the amplitude of the response is greater than a predetermined norm (H), established according to the results of control checks of the same type of strain gauges on the testing equipment, TP is recognized as unsuitable and is replaced with a new one.

Thus, the presented information indicates that the following set of conditions is fulfilled when using the claimed group of inventions:

- means embodying the claimed device in its implementation, reproduces the claimed method, intended for use in measuring equipment, namely strain gauges, to determine the quality control of gluing strain gages before conducting research.

- for the claimed group of inventions in the form in which it is characterized in the claims, the possibility of its implementation is confirmed using the devices described in the application and known before the priority date.

Therefore, the claimed group of inventions meets the condition of "industrial applicability".

Claims (2)

1. A quality control device for sticking resistance strain gages containing a test strain gauge glued to the strain gauge object, a resistor, a power source, an amplifier connected to a band-pass filter, and an internal half-bridge, characterized in that it is equipped with spark protection barriers, a digital oscilloscope, a personal computer and a loading device a strain gauge, in the case of which a spring-loaded rod is installed, on the one hand the rod is fixed by the case cover, on the other hand it protrudes beyond The housing is equipped with a nozzle with a tip made of sticky material, a sleeve is installed in the housing, between which and the lid is a spring, the fixture contains a stopper in the form of a vertical plate, one part of which is fixed to the housing, and the other rests on the object of strain measurement, the rod is installed in such a way that the tip is in contact with the strain gauge, and with the ability to move a distance, limited by the movement of the spring, the power source is connected to the first barrier of spark protection, the midpoint of the half-bridge, about Resistive resistance strain gage, connected to the second spark protection barrier, which is connected to an AC amplifier, and band-pass filter is connected to a digital oscilloscope connected to a personal computer. 2. The method of quality control sticking strain gauges, which consists in the fact that the glued strain gauge load and change its resistance is judged on the quality of gluing, characterized in that the strain gauge load fixture according to claim 1 through the tip several cycles of alternating efforts with a frequency up to 10 Hz and register change resistance of the strain gauge.

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