WO2005045360A1 - Method for calibrating a layer thickness measuring machine - Google Patents

Method for calibrating a layer thickness measuring machine Download PDF

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Publication number
WO2005045360A1
WO2005045360A1 PCT/EP2004/052462 EP2004052462W WO2005045360A1 WO 2005045360 A1 WO2005045360 A1 WO 2005045360A1 EP 2004052462 W EP2004052462 W EP 2004052462W WO 2005045360 A1 WO2005045360 A1 WO 2005045360A1
Authority
WO
WIPO (PCT)
Prior art keywords
eddy current
current sensor
layer thickness
inserts
distance
Prior art date
Application number
PCT/EP2004/052462
Other languages
German (de)
French (fr)
Inventor
Andreas Jungk
Original Assignee
Continental Aktiengesellschaft
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
Priority to DE2003152043 priority Critical patent/DE10352043A1/en
Priority to DE10352043.0 priority
Application filed by Continental Aktiengesellschaft filed Critical Continental Aktiengesellschaft
Publication of WO2005045360A1 publication Critical patent/WO2005045360A1/en

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00Measuring arrangements characterised by the use of electric or magnetic means
    • G01B7/02Measuring arrangements characterised by the use of electric or magnetic means for measuring length, width or thickness
    • G01B7/06Measuring arrangements characterised by the use of electric or magnetic means for measuring length, width or thickness for measuring thickness
    • G01B7/10Measuring arrangements characterised by the use of electric or magnetic means for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance
    • G01B7/107Measuring arrangements characterised by the use of electric or magnetic means for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance for measuring objects while moving
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00Measuring arrangements characterised by the use of electric or magnetic means
    • G01B7/02Measuring arrangements characterised by the use of electric or magnetic means for measuring length, width or thickness
    • G01B7/06Measuring arrangements characterised by the use of electric or magnetic means for measuring length, width or thickness for measuring thickness
    • G01B7/10Measuring arrangements characterised by the use of electric or magnetic means for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance
    • G01B7/105Measuring arrangements characterised by the use of electric or magnetic means for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance for measuring thickness of coating

Abstract

The invention relates to a method for calibrating a layer thickness measuring machine for products (10), comprising electrically conducting inserts (2) that are arranged in a substantially periodical manner and that are coated with or embedded in an electrically non-conducting material. An eddy current sensor (1) is displaced relative to the product (10) at a predetermined distance thereto. The layer thickness (SD) is determined from the difference of the distance of the eddy current sensor (1) to the product (10) and the measured distance to the inserts (2). The aim of the invention is to provide a simplified method for calibrating a layer thickness measuring machine of the aforementioned type. According to the invention, the distances (A) of the inserts (2) relative one another are determined by means of the eddy current sensor (1) and the layer thickness value (SD) is calibrated with an associated calibration value (K) in accordance with the distances (A) of the inserts (2).

Description

Continental Aktiengesellschaft

description

Procedure for the calibration of a layer thickness measuring machine

The invention relates to a method for calibrating a layer thickness measuring machine for products with essentially periodically arranged, electrically conductive inserts, which are coated with an electrically non-conductive material or embedded in such a material, in which an eddy current sensor relative to the product in a fixed distance is moved and the layer thickness of the electrical non-conductive material is determined from the difference between the distance of the eddy current sensor to the product and the measured distance to the inserts.

It is known from the prior art to measure the layer thickness of a motor vehicle tire with an eddy current sensor which is guided along at a defined distance from the rubber surface of the tire, preferably in the shoulder area of the inner layer. The measurement result depends on the so-called steel cord and the spacing, i.e. the distance between the steel cord threads. In the case of changing steel cord and / or changing spacing, a calibration measurement must be carried out using the conventional method. The steel cord is known during production and is mostly uniform. The spacing changes from dimension to dimension of the tire and depending on the radius of the measuring track to the tire axis of rotation. The calibration is carried out by a reference measurement against a calibration plate, which is specially made for each spacing with the respective steel cord.

The object of the invention is to provide a method for a simplified calibration of a layer thickness measuring machine. According to the invention, this object is achieved in that the distances between the deposits are determined via the eddy current sensor and the layer thickness value is calibrated as a function of the distances between the deposits with an assigned calibration value. The measurement result, which is dependent on the measurement of the insoles and the spacing of the insoles relative to one another, can now be determined automatically, so that a calibration plate and a corresponding upstream calibration method are no longer necessary. The layer thickness of the electrical non-conductive material can thus be measured reliably in a simple manner, calibration being carried out during the measurement and changes in the product to be measured being detected.

A further development of the invention provides that the products of motor vehicle tires and the inserts are a steel cord, that is to say that the layer thickness, in particular the rubber coating of the tire, is measured as a function of the tire dimension and the steel cord carcass. A calibration then takes place depending on the tire size and the steel cord used.

The periodic arrangement of the inserts makes it possible to record a pulsating measurement signal of a certain frequency with the eddy current sensor. From the quotient of the relative speed between the product, for example motor vehicle tires and the eddy current sensor, and the frequency of the measurement signals, the distance or spacing between the individual inserts or the steel cord threads can be determined. The distance or spacing of the inlays results from the speed of the eddy current sensor transverse to the orientation of the inlays or the thread direction divided by the frequency of the measurement signal. A calibration value is assigned to each value of a distance with the respective insert or the respective steel cord, which results in a calibration function. The calibration value is formed from the calibration function depending on the spacing and the nature of the insert or the type of steel cord. The correct layer thickness value is then determined as the product of the calibration value and the measured layer thickness. The calibration values are determined for a selection of distances or spacings and stored in a memory, in particular in a measurement computer. The corresponding calibration values are called up from this measurement computer depending on the specified type of insert or type of steel cord and used to determine the calibration factor.

In order to be able to determine the spacing of the deposits from one another in the case of deposits which are arranged essentially periodically, it is necessary to know the relative speed between the eddy current sensor and the deposits. An alternative of the invention provides that the relative speed is determined with a speed sensor, which is preferably arranged on the same measuring track as the eddy current sensor. In this way, a necessary correction of the relative speed due to different measuring track radii is avoided.

As an alternative to this, it is provided that the relative speed is determined from the rotational speed of the motor vehicle tire and the radius of the eddy current sensor to the axis of rotation of the motor vehicle tire. If the radius of the eddy current sensor to the axis of rotation of the product or the motor vehicle tire is known, the speed of the eddy current sensor relative to the surface of the product can be determined by calculation.

Furthermore, it is provided that a family of calibration values is determined over the range of the resulting spacings or spacings for the respective materials, and the calibration function is calculated therefrom.

The structure and sequence of the calibration method are explained in more detail below with the aid of the figure. The figure shows schematically a layer thickness measuring machine for motor vehicle tires with a connected measuring computer.

In the figure, a motor vehicle tire 10 is shown, which is designed as a steel cord carcass tire, that is to say has the steel cord thread 2 as a carcass, which are embedded in a rubber mixture. While the steel cord threads 2 can be detected by an eddy current sensor 1, the layer thickness, that is the Thickness of the rubber layer can only be measured indirectly by moving the eddy current sensor at a fixed distance from the surface of the motor vehicle tire 10 relative to it. The fixed distance or the fixed distance can be ensured, for example, by an impeller or a sliding shoe.

The Wiibel current sensor 1 thus measures the distance to the steel cords 2, and the layer thickness of the electrically non-conductive rubber layer is calculated from the difference between the measured distance and the specified distance from the surface of the motor vehicle tire 10.

The eddy current sensor 1 has a separate arrangement of the transmitting and receiving coils and thus has a narrow measuring field. Therefore, the measurement signal of the eddy current sensor 1 pulsates when the measurement track 5 is traversed, the frequency of the measurement signal corresponding to the throughput frequency of the steel cord threads 2. The spacing A of the inserts 2 from one another, that is to say the spacing of the steel cord threads 2, results from the speed V of the eddy current sensor 1 relative and transverse to the steel cord thread direction, divided by the frequency F of the measurement signal. Expressed as an equation, the space is: A = V / F.

The drawing also shows that a speed sensor 4 is present which detects the relative speed V, for example due to a rotation of the motor vehicle tire 10 relative to the eddy current sensor 1. The speed sensor 4 is expediently arranged on the same measuring track 5 as the eddy current sensor 1, so that the speed data can be adopted unchanged. As an alternative to a speed sensor 4, the speed of the eddy current sensor 1 relative to the motor vehicle tire 10 can also be determined from the rotational speed of the motor vehicle tire and the distance R of the sensor 1 from the tire rotation axis.

In the left part of the figure, a cross section of a motor vehicle tire 10 is shown, in which it is shown that both the eddy current sensor 1 and the Ge speed sensor 4 is preferably arranged in the shoulder region of the inner layer on a common measuring track 5.

The measured value of the eddy current sensor 1 is fed to a measuring computer 3 and there to an oscillator 6 which amplifies and linearizes the signal.

The measurement signals of the speed sensor 4 are fed to a speed measurement amplifier 7 within the measurement computer 3. The measurement signals of the eddy current sensor are subjected to a frequency analysis in a frequency analyzer 16, the frequency of the measurement signal U corresponding to the throughput frequency of the steel cords. The frequency is combined with the measurement signal Uv of the relative speed V and the distance A or the spacing is calculated therefrom. A calibration function KF is stored in the measuring computer 3. The calibration function KF is calculated by determining a set of calibration values over the area of the resulting spacings A with the respective steel cord types S when the system or the measuring machine is started up.

The steel cord type is generally known during ongoing production and is mostly uniform. The distance or the spacing A, however, changes from dimension to dimension and depending on the radius of the measuring track 5 to the tire axis of rotation. During the measurement, the measuring computer 3 determines the frequency from the data of the eddy current sensor 1, the signals of the relative speed V are supplied by a speed sensor 4 which is arranged on the measuring track 5 of the eddy current sensor 1. The measuring computer 3 calculates the space or the spacing A, selects the calibration value K belonging to the spacing A and steel cord S from the stored calibration function KF and calculates the applicable layer thickness value SD from the calibration value K and the measured distance from the steel cord threads 2. Thus, the layer thickness measuring machine recognizes given

Steel cord S the spacing A and automatically calculates the layer thickness SD. Calibration by measuring against corresponding calibration plates between the layer thickness measurements of different tire dimensions is not necessary. Basically, the method described can be used for all distance measurements against mesh systems made of electrically conductive materials which are embedded or coated in electrically non-conductive materials or media and in which the sensor moves relative to the measurement object.

Claims

1. A method for calibrating a layer thickness measuring machine for products (10) with periodically arranged, electrically conductive inserts (2) which are coated with an electrically non-conductive material or embedded in such a material in which an eddy current sensor (1 ) is moved relative to the product (10) at a fixed distance and from the difference between the distance of the eddy current sensor (1) to the product (10) and the measured distance to the inserts (2) the layer thickness ( SD), characterized in that the eddy current sensor (1) determines the distances (A) of the inserts (2) from one another and the layer thickness value (SD)
 depending on the distances (A) of the inserts (2) is calibrated with an assigned calibration value (K).
2. The method according to claim 1, characterized in that the products (10) motor vehicle tires and the inserts (2) are a steel cord.
3. The method according to claim 1 or 2, characterized in that from the quotient of the relative speed (V) between the product (10) and the eddy current sensor (1) and the frequency (F) of the measurement signals, the distance (A) between the deposits ( 2) and the dimensions thereof are determined, a calibration function (KF) being assigned to each value of the distance (A) and the calibration value (K) being calculated therefrom.
4. The method according to any one of the preceding claims, characterized in that the calibration values (K) for a selection of distances (A) are determined and stored in a memory (3), in particular in a measuring computer.
5. The method according to any one of the preceding claims, characterized in that the layer thickness (SD) in a measuring computer (3) from the  <Desc / Clms Page number 8>   Calibration value (K) and the difference between the distance of the eddy current sensor (1) from the product (10) and the measured distance from the inserts (2) is determined.
6. The method according to any one of the preceding claims, characterized in that the relative speed (V) is determined with a speed sensor (4).
7. The method according to claim 6, characterized in that the speed sensor (4) and the eddy current sensor (1) are arranged on a common measuring track (5).
8. The method according to any one of claims 2 to 5, characterized in that the relative speed (V) from the speed of the motor vehicle tire (10) and the radius (R) of the eddy current sensor (1) to the axis of rotation of the motor vehicle tire (10 ) is determined.
9. The method according to any one of the preceding claims, characterized in that a family of calibration values (K) is determined over the range of the resulting distances (A) for the respective materials and the calibration function (KF) is calculated therefrom.
PCT/EP2004/052462 2003-11-07 2004-10-07 Method for calibrating a layer thickness measuring machine WO2005045360A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE2003152043 DE10352043A1 (en) 2003-11-07 2003-11-07 Method for calibrating a coating thickness measuring machine
DE10352043.0 2003-11-07

Publications (1)

Publication Number Publication Date
WO2005045360A1 true WO2005045360A1 (en) 2005-05-19

Family

ID=34559459

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2004/052462 WO2005045360A1 (en) 2003-11-07 2004-10-07 Method for calibrating a layer thickness measuring machine

Country Status (2)

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DE (1) DE10352043A1 (en)
WO (1) WO2005045360A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2645404A1 (en) * 1976-10-08 1978-04-13 Continental Gummi Werke Ag Reinforcing supports bedding depth measuring appts. for tyres - has test rod forced against and between support cords or wires to also indicate spacing
JPH08304009A (en) * 1995-05-10 1996-11-22 Sumitomo Rubber Ind Ltd Apparatus and method for measurement of tire-surface rubber thickness
EP1189014A2 (en) * 2000-09-14 2002-03-20 Bridgestone Corporation Method of measuring a gauge of a used rubber portion of a buffed tire and buffing method
EP1211477A1 (en) * 2000-11-23 2002-06-05 Electronic Systems S.P.A. Measurement of the unbalancing of a ferromagnetic metal core in a nonconductive and nonferroelectric ribbon

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3919131A1 (en) * 1989-06-12 1990-12-13 Tzn Forschung & Entwicklung Device and method for contactless measurement of the layer thickness of a non-conductive material, and use of the device for measuring plastic-covered metal parts
US5343146A (en) * 1992-10-05 1994-08-30 De Felsko Corporation Combination coating thickness gauge using a magnetic flux density sensor and an eddy current search coil
DE4334380C2 (en) * 1993-10-08 2000-10-26 Micro Epsilon Messtechnik Method for calibrating a sensor and processing measured values

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2645404A1 (en) * 1976-10-08 1978-04-13 Continental Gummi Werke Ag Reinforcing supports bedding depth measuring appts. for tyres - has test rod forced against and between support cords or wires to also indicate spacing
JPH08304009A (en) * 1995-05-10 1996-11-22 Sumitomo Rubber Ind Ltd Apparatus and method for measurement of tire-surface rubber thickness
EP1189014A2 (en) * 2000-09-14 2002-03-20 Bridgestone Corporation Method of measuring a gauge of a used rubber portion of a buffed tire and buffing method
EP1211477A1 (en) * 2000-11-23 2002-06-05 Electronic Systems S.P.A. Measurement of the unbalancing of a ferromagnetic metal core in a nonconductive and nonferroelectric ribbon

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 199706, Derwent World Patents Index; AN 1997-055822, XP002257959 *
PATENT ABSTRACTS OF JAPAN vol. 1997, no. 03 31 March 1997 (1997-03-31) *

Also Published As

Publication number Publication date
DE10352043A1 (en) 2005-06-09

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