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DE3015973A1 - Corrosion-proof application of high temp. strain gauges - using metal coatings of same alloy as measurement body ensuring protection without reduction of accuracy - Google Patents

Corrosion-proof application of high temp. strain gauges - using metal coatings of same alloy as measurement body ensuring protection without reduction of accuracy

Info

Publication number
DE3015973A1
DE3015973A1 DE19803015973 DE3015973A DE3015973A1 DE 3015973 A1 DE3015973 A1 DE 3015973A1 DE 19803015973 DE19803015973 DE 19803015973 DE 3015973 A DE3015973 A DE 3015973A DE 3015973 A1 DE3015973 A1 DE 3015973A1
Authority
DE
Germany
Prior art keywords
strain gauge
strain gauges
measuring body
corrosion
holes
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
DE19803015973
Other languages
German (de)
Inventor
Claus 6246 Glashütten Säuberlich
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Battelle Institut eV
Original Assignee
Battelle Institut eV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Battelle Institut eV filed Critical Battelle Institut eV
Priority to DE19803015973 priority Critical patent/DE3015973A1/en
Publication of DE3015973A1 publication Critical patent/DE3015973A1/en
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
    • G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
    • G01L1/2287—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges constructional details of the strain gauges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/20—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by detection of dynamic effects of the flow
    • G01F1/28—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by detection of dynamic effects of the flow by drag-force, e.g. vane type or impact flowmeter

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

The method is esp. applicable to measurement of flow forces at high temp. corrosive fluids using a flexible beam system. The method ensures complete protection of the strain gauges without affecting the measurement accuracy. Small tubular strain gauges without soldering lugs are used. They are inserted in holes (1) drilled in the measurement body (2) and the contacts to them made by brazing. The holes are drilled near the surface of the measurement body which is of the same material, an Ni-Cr-15fe alloy, as the strain gauge protective coating. Solder with a high silver content is placed in the holes and fills the gaps between the walls of the holes and the strain gauge by capillary action during brazing by a h.f. induction coil.

Description

Verfahren zur korrosionsgeschtzten Applikation von Process for the corrosion-protected application of

metallummantelten Hochtemperatur-Dehnungsmeßstreifen Die Erfindung betrifft ein Verfahren zur korrionsgeschützten Applikation von metallummantelten Hochtemperatur-Dehnungsmeßstreifen an Meßkörper. Das Verfahren ist insbesondere zur Anbringung von Dehnungsmeßstreifen an einem bei hohen Temperaturen in aggressiven Fluiden zur Strömungskraftmessung verwendeten Biegebalkensystem geeignet. Metal Clad High Temperature Strain Gauges The Invention relates to a method for the corrosion-protected application of metal-coated High temperature strain gauges on the measuring body. The procedure is particular for attaching strain gauges to an aggressive at high temperatures Bending beam system used for flow force measurement fluids.

Bei Massenstrommessungen unter Verwendung von Widerstandskörpern werden metallummantelte Dehnungsmeßstreifen, die einen Schweißflansch aufweisen, durch Punktschweißung am Meßkörper befestigt (G. Hampel, Measurement of the Mass Flow of Transient Two-Phase Flow by Means of Drag-Body and Gamma-Ray- Attenuation Method", Vortrag, veröffentlicht in Transient Two-Phase Flow, Proceedings of the CSNI Specialists Meeting in Toronto, August 1976, printed by Atomic Energy of Canada, Mai 1978). Eine solche Applikation bringt jedoch insbesondere in einer Dampf-Wasser-Gemischströmung Probleme mit sich. Die einzelnen Schweißpunkte können sich nach erhöhter dynamischer und temperaturmäßiger Beanspruchung leicht lösen und damit eine Verschlechterung des Übertragungsverhaltens verursachen.For mass flow measurements using resistance bodies metal-sheathed strain gauges that have a welding flange Spot welding attached to the measuring body (G. Hampel, Measurement of the Mass Flow of Transient Two-Phase Flow by Means of Drag-Body and Gamma-Ray- Attenuation Method ", lecture published in Transient Two-Phase Flow, Proceedings of the CSNI Specialists Meeting in Toronto, August 1976, printed by Atomic Energy of Canada, May 1978). However, such an application is particularly effective in a steam-water mixture flow Problems with yourself. The individual welding points can become more dynamic after increased and temperature-related stress easily and thus a deterioration of the transmission behavior.

Ferner fahrt die Punktschweißung zu Gefügeveränderungen im Meßkörper, wodurch die Festigkeitseigenschaften hegativ.beeinflußt werden. Beim Einsatz des Meßkörpers in Wasser-Dampf-Gemischen bestehen außerdem an den an der Oberfläche applizierten Dehnungsmeßstreifen Angriffsstellen für Spaltkorrosion, so daß selbst die Verwendung hochresistenter Stahlsorten für die Ummantelung des Dehnungsmeßstreifens keinen ausreichenden Schutz bietet und es zu Ausfällen des Meßsystems kommen kann.Furthermore, the spot welding leads to structural changes in the measuring body, whereby the strength properties are negatively influenced. When using the Measuring bodies in water-steam mixtures also exist on the surface applied strain gauges attack points for crevice corrosion, so that even the use of highly resistant types of steel for the sheathing of the strain gauge does not provide adequate protection and failure of the measuring system can occur.

Es wurde bereits vorgeschlagen, die Dehnungsmeßstreifen abzudecken oder durch Flamm-Spray-Verfahren anzubringen. Diese Methoden weisen zusätzliche technische Schwierigkeiten auf und führen auch nicht zum erforderlichen Korrosionsschutz, da poröse Oberflächen und gefährdete Materialpaarungen in Kontakt mit dem aggressiven Medium bleiben.It has already been suggested to cover the strain gauges or by using a flame spray method. These methods have additional technical difficulties and do not lead to the necessary corrosion protection, because porous surfaces and endangered material pairings in contact with the aggressive Remain medium.

Der vorliegenden Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren anzugeben, mit dem in einfacher Weise und ohne Beeinflussung der Meßgenauigkeit ein vollkommener Schutz der metallummantelten Hochtemperatur-Dehnungsmeßstreifen gewährleistet ist.The present invention is therefore based on the object a Specify method with which in a simple manner and without influencing the measurement accuracy a perfect protection of the metal-sheathed high-temperature strain gauges is guaranteed.

Es hat sich nun gezeigt, daß sich diese Aufgabe lösen läßt, wenn ein röhrchenförmiger Dehnungsmeßstreifen ohne Schweißflansch verwendet wird und dieser in einer Bohrung im Meßkörper eingebracht und mittels Hartlötung kontaktiert wird. Vorteilhafte Ausführungsformen des erfindungsgemäßen Verfahrens sind in den Unteransprüchen 2 bis 6 erläutert.It has now been shown that this problem can be solved if a tubular strain gauge without welding flange is used and this is introduced into a bore in the measuring body and contacted by means of brazing. Advantageous embodiments of the method according to the invention are set out in the subclaims 2 to 6 explained.

Damit ein genügend großer Meßeffekt erhalten bleibt, wird die Bohrung vorzugsweise dicht unter der Oberfläche des Meßkörpers, z.B. des Biegebalkens, angebracht. Zur Erzielung eines gleichen Wärmeausdehnungskoeffizienten zwischen Dehnungsmeßstreifen und der Wandung der Bohrung empfiehlt es sich, daß die Ummantelung des Dehnungsmeßstreifens und der Meßkörper aus demselben Material bestehen. Vorzugsweise werden eine Dehnungsmeßstreifenummantelung und ein Meßkörper aus Nickel-Chrom-Stahl, z.B. Ni-Cr-15Fe, Stahl-Nr. 2.4816 nach DIN 17007 (Tnconelstahl), verwendet, der sich in seiner Korrosionsbeständigkeit und Verlötbarkeit als besonders geeignet erwiesen hat. In die Bohrung wird zunächst die entsprechende Menge Lot, z.B. ein hoch silberhaltiges Lot mit gutem Spaltflußverhalten> abgesenkt und das Dehnungsmeßstreifenröhrchen eingesteckt. Zur Lötung kann der den Dehnungsmeßstreifen enthaltende Meßkörper anschließend in eine KF-Induktionsspule eingebracht und bis auf etwa 650 °C erwärmt werden. Durch die Kapillarwirkung füllt das geschmolzene Lot den Spalt zwischen der Wandung der Bohrung und dem Dehnungsmeßstreifen und ermöglicht eine gute Kontaktierung.In order to maintain a sufficiently large measuring effect, the bore preferably mounted just below the surface of the measuring body, e.g. the bending beam. To achieve the same coefficient of thermal expansion between strain gauges and the wall of the bore, it is recommended that the sheathing of the strain gauge and the measuring body consist of the same material. A strain gauge sheathing is preferred and a measuring body made of nickel-chromium steel, e.g. Ni-Cr-15Fe, steel no. 2.4816 after DIN 17007 (Tncon steel), used, which is in its corrosion resistance and solderability has proven particularly suitable. In the hole is first the corresponding amount of solder, e.g. a high-silver solder with good Gap flow behavior> lowered and the strain gauge tube inserted. For soldering, the measuring body containing the strain gauge can then be turned into a KF induction coil can be inserted and heated up to about 650 ° C. By the capillary action fills the molten solder the gap between the wall of the Bore and the strain gauge and enables good contact.

In der beiliegenden Figur wird das erfindungsgemäße Verfahren am Beispiel eines Biegebalkens näher erläutert.In the accompanying figure, the method according to the invention is illustrated using the example a bending beam explained in more detail.

Appliziert werden soll dabei ein Dehnungs.meßstreifen von 0,9 mm Durchmesser und etwa 30 mm aktiver Länge. Hierfür wird eine Bohrung 1 von 1,1 mm Durchmesser und etwa 30 mm Tiefe in den Meßkörper 2 bzw. in den B.iegebalken eingebracht. Eine UbergangshUlse 3 dient zur Aufnahme der Verbindung von Dehnungsmeßstreifen und Meßkabel. Die Meßkabel werden dann an die entsprechenden und hier nicht gezeichneten Meßvorrichtungen geführt.A strain gauge with a diameter of 0.9 mm is to be applied and about 30 mm active length. A hole 1 with a diameter of 1.1 mm is used for this and about 30 mm deep in the measuring body 2 or in the B. bending beam. One Transition sleeve 3 is used to accommodate the connection between strain gauges and measuring cables. The measuring cables are then connected to the corresponding measuring devices (not shown here) guided.

Da die Bohrung nahe der Oberfläche des Meßkörpers angebracht wird, bleibt die Meßkörperoberfläche vollkommen unbeeinflußt von der Applikation des Dehnungsmeßstreifens. Eine Korrosionsgefährdung infolge von Spaltangriffsstellen oder Materialunverträglichkeit ist somit ausgeschlossen. Da der Dehnungsmeß- streifen ohne Schweißflansch verwendet wird und somit einen geringeren Platzbedarf hat, können mehrere Meßstreifen in nebeneinanderliegenden Bohrungen auch in kleineren Meßkörpern angebracht werden.Since the hole is made close to the surface of the measuring body, the surface of the measuring body remains completely unaffected by the application of the strain gauge. A risk of corrosion as a result of crack attack points or material incompatibility is therefore excluded. Since the strain gauge strip without welding flange is used and therefore takes up less space, several measuring strips can be used can also be installed in adjacent bores in smaller measuring prisms.

Mit der Lötverbindung wird eine vollständige Kontaktierung von Dehnungsmeßstreifenmantel und Meßkörper erzielt. Beide Effekte führen zu einem verbesserten Übertragungsverhalten und damit zu einer erhöhten Meßempfindlichkeit und zu einem höheren Meßausgangssignal.With the soldered connection, a complete contact is made with the strain gauge jacket and measuring body achieved. Both effects lead to an improved transmission behavior and thus to an increased measurement sensitivity and to a higher measurement output signal.

LeerseiteBlank page

Claims (6)

Patentansprüche Verfahren zur korrosionsgeschützten Applikation von metallummantelten Hochtemperatur-Dehnungsmeßstreifen an Meßkörper, dadurch gekennzeichnet, daß ein röhrchenförmiger Dehnungsmeßstreifen ohne Schweißflansch verwendet wird und dieser in eine Bohrung im Meßkörper eingebracht und mittels Hartlötung kontaktiert wird. Method for the corrosion-protected application of metal-sheathed high-temperature strain gauges on measuring body, characterized in that that a tubular strain gauge without a welding flange is used and this is introduced into a bore in the measuring body and contacted by means of brazing will. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Bohrung nahe der Oberfläche des Meßkörpers angebracht wird.2. The method according to claim 1, characterized in that the bore is attached near the surface of the measuring body. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Ummantelung des Dehnungsmeßstreifens und der Meßkörper aus demselben Material bestehen.3. The method according to claim 1 or 2, characterized in that the Sheathing of the strain gauge and the measuring body consist of the same material. 4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, daß die Ummantelung des Dehnungsmeßstreifens und der Meßkörper aus einer Ni-Cr-15Fe-Legierung bestehen.4. The method according to claim 3, characterized in that the casing the strain gauge and the measuring body are made of a Ni-Cr-15Fe alloy. 5. Verfahren-nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß in die Bohrung zunächst die entsprechen-de Menge Lot eingebracht wird, das während des Lötvorgangs durch Kapillarwirkung den Spalt zwischen der Wandung der Bohrung und dem Dehnungsmeßstreifen füllt und die Kontaktierung ermöglicht.5. The method according to any one of claims 1 to 4, characterized in that that the corresponding amount of solder is first introduced into the hole, which during of the soldering process by capillary action, the gap between the wall of the hole and the strain gauge fills and enables contact. 6. Verfahren nach einem der Ansprüche 1 bis- 5, dadurch gekennzeichnet, daß ein hoch silberhaltiges, spaltfl.ußgeeignetes Lot verwendet und die Lötung mittels HF-Induktionsspule in Normalatmosphäre vorgenommen wird.6. The method according to any one of claims 1 to 5, characterized in that that a high silver content, gap flow suitable solder is used and the soldering with HF induction coil is made in a normal atmosphere.
DE19803015973 1980-04-25 1980-04-25 Corrosion-proof application of high temp. strain gauges - using metal coatings of same alloy as measurement body ensuring protection without reduction of accuracy Ceased DE3015973A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE19803015973 DE3015973A1 (en) 1980-04-25 1980-04-25 Corrosion-proof application of high temp. strain gauges - using metal coatings of same alloy as measurement body ensuring protection without reduction of accuracy

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Application Number Priority Date Filing Date Title
DE19803015973 DE3015973A1 (en) 1980-04-25 1980-04-25 Corrosion-proof application of high temp. strain gauges - using metal coatings of same alloy as measurement body ensuring protection without reduction of accuracy

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DE3015973A1 true DE3015973A1 (en) 1981-11-05

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19910732A1 (en) * 1999-03-11 2000-09-14 Matthias Limburg Worm press flow conditions measuring device used in ceramic industry has several electrical conductors or semiconductors, whose shape change results in change of their length
DE10216532B4 (en) * 2002-04-15 2007-02-22 Sensorentechnologie Gettorf Gmbh Sensor and method for its production

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH353556A (en) * 1956-03-02 1961-04-15 Duncan Russell John Voltmeter
GB882445A (en) * 1958-11-19 1961-11-15 Ali Umit Kutsay Improvements in or relating to strain gauges
DE1129728B (en) * 1953-11-09 1962-05-17 John D Russell Electrical extensometer, consisting of resistance wire, metallic connecting link and heat-resistant insulating body

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1129728B (en) * 1953-11-09 1962-05-17 John D Russell Electrical extensometer, consisting of resistance wire, metallic connecting link and heat-resistant insulating body
CH353556A (en) * 1956-03-02 1961-04-15 Duncan Russell John Voltmeter
GB882445A (en) * 1958-11-19 1961-11-15 Ali Umit Kutsay Improvements in or relating to strain gauges

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Experimental Mechanics, August 1967, S. 19A-26A *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19910732A1 (en) * 1999-03-11 2000-09-14 Matthias Limburg Worm press flow conditions measuring device used in ceramic industry has several electrical conductors or semiconductors, whose shape change results in change of their length
DE10216532B4 (en) * 2002-04-15 2007-02-22 Sensorentechnologie Gettorf Gmbh Sensor and method for its production

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