DE102010051394A1 - Method for tracking unique materials of hollow structure e.g. ferromagnetic steel pipe, involves providing distinct marks for identification of material at pipe surface, in form of magnetic marks in different directions of magnetization - Google Patents

Abstract

The method involves providing distinct marks for identification of material at the surface of pipe (1), in the form of magnetic marks in different directions of magnetization. The magnetic marks are formed in the longitudinal or circumferential direction of the pipe, as bar code or data matrix codes.

Description

The invention relates to a method for item tracking of hollow bodies made of steel, in particular of ferromagnetic steel tubes, according to the preamble of claim 1.

As part of the optimization of quality assurance and the costs in the manufacturing process in the adjustment of pipes, the traceability of the finished product, d. H. when is what where where made, of crucial importance.

Inextricably linked with this is the unmistakable identification of each individual tube as it goes through all the specified manufacturing and test steps. Especially in areas with typical mass production, such as in a tube mill where hundreds to thousands of individual tubes are moved, processed and tested at the same time, individual item tracking is a central issue. In addition, customers increasingly demand proof of single piece tracking under quality assurance aspects.

In the past, various methods have been used to identify the individual pieces in the sense of pursuit, but they no longer meet today's requirements.

By way of example, the rolling or production lot is selected as the smallest identity unit, wherein usually the same melt and the same final dimension form one lot. The number of tubes of a lot is initially determined either by hand or via a counter and during the passage of the failure of one or more tubes is registered at the respective manufacturing stations.

Large lots are divided into leagues, which are numbered consecutively and held together by wires. For identification z. B. an identification card provided with this number inserted with a bent wire in one of the tubes. When transporting the bundles sometimes across several factory halls, it can not be ruled out that identity cards will be lost or fall out when the league is opened and then accidentally put in the wrong league.

Other systems use hand-painted or machine-stamped identification numbers, with glued-on or die-cut labels, or with laser-engraved identifications.

All of these known methods have disadvantages because the respective identification applied for identification is either not always readable, for. B. because of excessive transport speed or if the label is on the underside of the tube or because they z. B. leads to false readings in an ultrasonic test, or the reliability of the detection during the run through all prescribed manufacturing and test steps is not given.

From the DE 195 05 513 C2 a method is known in which a barcode is applied by color markings directly to each individual workpiece for the identification of the tubes, in each case with an extension over the entire transverse circumference of the tube. Thus, the reading of the barcode is independent of the circumferential position of the tube. The barcode is recorded by video image, which means that it is independent of the direction of transport.

This known method for single piece tracking also has disadvantages. Due to the handling of the tubes as they pass through the individual production and testing facilities and when unrolling the tubes on the roller tables, the barcode applied by means of color markings can be damaged, making it difficult or even impossible to record optically.

For reliable optical detection of the bar code, the line markings must not be too narrow because of the rough-rough surface of the tubes, since fraying must be expected which the evaluation system can no longer distinguish as separate color lines. This leads to a relatively long axial extent of the bar code over the tube length, and is often rejected by the customer for optical reasons.

Another method is in the DE 10 2004 051 124 B3 and the DE 10 2008 030 183 B4 disclosed. In this method, the individual seamlessly hot-finished tube is identified for identification after a last hot work with a distinctive over the entire pipe circumference extending label and read in the feed area to the subsequent manufacturing or testing stations during further transport regardless of the transport direction automatically as a video image. The unmistakable marking is applied as a data matrix code in multiple identical repetition on the pipe circumference.

The data matrix codes are applied in one or more tracks annular or helical or as a segmented label in one or more pipe circuits.

Single-piece tracking of pipes labeled with Data Matrix codes has developed in the Practice proven excellent, but it has been shown that the application and reading of the markers requires a lot of equipment, which affects the economics of this method.

In addition, these marks can be damaged in the possible subsequent straightening, so that their readability is not or only to a limited extent possible. In addition, they are often perceived as annoying by customers.

The object of the invention is to provide a safe and cost-effective method for tracking individual pieces of hollow bodies, in particular of pipes made of ferromagnetic steel, which avoids the disadvantages of the known markings.

According to the invention the object is achieved in that the material is provided on the pipe surface with an identification mark in the form of magnetic markings of different magnetization directions for the identification of the hollow body.

This method is suitable both for seamlessly hot-made tubes, and also for cold-made, such. As precision tubes, suitable. For the hot-finished tubes, the magnetic markers are applied to the tube surface after the last hot working cycle, when the material has fallen below the Curie temperature again.

In contrast to the known methods, the marking used for identification is no longer applied to the tube in the form of visible data matrix codes or other color markings, but in the form of an invisible magnetic coding (identification mark) to be applied simply and cost-effectively to the tube. which is generated by different polarization of the magnetic field of electromagnets (negative or positive) on the pipe surface. The application of the markings at the different tube positions is done by a relative movement between the tube and the electromagnet, wherein the marking is carried out either with moving tube by fixedly arranged magnets or by the electromagnets are moved over the stationary tube.

By introducing the coding in the material a stable marking is achieved, which can be read with little effort at each longitudinal transport of the tube. Compared to the known markers, which are z. T. extend over several meters of pipe length, a comparatively short mark length is sufficient.

The marking is not visible and can be removed again if necessary by simple demagnetization. In addition, the method according to the invention can be easily automated and easily integrated into existing production processes.

The coding can advantageously be applied in annular circumferential markings or, if necessary, as a longitudinal marking on the surface of the tube.

In the circumferential marking, an electromagnet is guided over the pipe surface during a rotation with a small radial gap, whereby a magnetization of the pipe is achieved at this point. By arranging a plurality of magnets in the longitudinal direction of the tube, a plurality of codings having different polarizations can then be applied simultaneously in the circumferential direction, which are then readable as a binary code. The annular marking allows read-out at any circumferential position during longitudinal transport. To secure the coding, it is expedient to distribute these multiple times over the pipe length or applied to both pipe ends.

It is also possible, the magnetic mark as distributed over the pipe circumference longitudinal mark z. B. apply during a longitudinal transport. Here, the longitudinal marking is applied by a plurality of fixedly arranged magnets in the different Umfangspostionen, wherein the individual markers for the introduction of a readable binary code may be different in polarization. In contrast to the circumferential marking, however, a start bit is to be provided for reading out the coding.

If necessary, the tube can also be moved helically under the stationary electromagnet, so that the electromagnetic markings also run helically.

If it is necessary for technical reasons, another possibility for applying the markings is to arrange them axially parallel to one another only in the longitudinal direction of the tube. For marking purposes, the number of electromagnets required for introducing the code is fixedly arranged in the longitudinal direction of the tube, or moved in the longitudinal direction of the tube. For detecting and reading out the markings z. B. stationary over the pipe circumference arranged reading units or rotating around the tube reading unit can be provided.

A magnetization of the material is basically also by a method single electromagnet over the workpiece surface possible, in which case the electromagnet must each change the polarization direction according to the applied identification mark.

A first embodiment of the invention provides to apply the marking or coding with the same stroke width as a binary code consisting of two different magnetization directions. Here, all the magnets have the same width, but it will be needed for the coding of an example five-digit pipe number seventeen marks (bits).

A very short marking area can be realized in an advantageous development of the invention by the use of a ternary (3-er) base as coding. This base consists of two different magnetization directions and an unmagnetized state. There are thus three possibilities to provide a marking position with a corresponding state. At a z. B. five-digit tube number, the coding can then be achieved with only eleven instead of seventeen Markierringen in circumferential markings or marking strips in longitudinal markings, whereby the required mark length is significantly reduced.

In further advantageous embodiments, the markings can be executed in addition to line-shaped dot-shaped, as a barcode with different line widths or as a data matrix code depending on the requirements.

When transporting with magnetic cranes, the tubes are generally struck in the central region, so that in these cases, the markings according to the invention should advantageously be applied to one or both end portions of the tubes, so that the magnetic mark is maintained even after transport. In principle, however, the markings can be attached anywhere on the tube circumference.

Further advantages and details of the invention will become apparent from the following description of the figures shown.

Show it:

1 1 is a schematic representation of a first embodiment with electromagnets for magnetic marking in the tube circumferential direction;

2a Circumferential markings as concentric circles according to 1 .

2 B a second embodiment with linear magnetic markings over the pipe circumference,

2c a third embodiment with linear magnetic markings in the tube longitudinal direction,

3 Reading out circumferential markings according to 2a ,

1 shows a schematic representation of the inventive method for the magnetic marking of tubes in the circumferential direction. To mark the pipe 1 are in the longitudinal direction of the tube on the tube outer surface with a small radial gap more electromagnets 2 fixedly arranged, under which the pipe 1 is moved in the circumferential direction, so that circumferential markings 3 as concentric circles according to 2a resulting in the identification mark as a whole.

2 B shows the case when the pipe 1 to receive an identification mark by means of magnetic longitudinal markings over its circumference. Not shown are to be arranged in different positions in the tube circumferential direction of this electromagnets 2 , These are adjusted so that different magnetization directions (negative, positive or non-magnetic) are individually adjustable for each magnet, so that by the applied magnetic markings the tube 1 receives an identification mark.

In 2c the case is shown when the pipe 1 only a linear marking in the longitudinal direction of the tube 1 should receive. Here are the markings 5 with different polarizations in the longitudinal direction of the tube 1 arranged and then can with one over the circumference of the pipe 1 arranged (not shown here) read unit to be read.

The readout of the magnetic coding is in the case of a circumferential mark with concentric circles according to FIG 2a in 3 shown.

The pipe 1 is in the beginning and end of each with magnetic markers as a circumferential mark 3 each extending over about 500 mm of the pipe length here. During the longitudinal transport of the pipe 1 to the next manufacturing station is by means of a mounted at a radial distance above the tube surface stationary reading unit 6 . 6 ' read out the magnetic identification mark and fed the data to an evaluation unit, not shown here.

The second reading unit 6 ' is not mandatory, but is advantageous for matching the read data with the reading unit 6 , so that This enables a secure and correct readout of the data.

• – optisch unsichtbare Markierung,
• – einfach, kostengünstig und schnell auf die Rohroberfläche aufbringbare Markierung
• – einfache Entfernbarkeit der Markierung durch Entmagnetisierung,
• – einfache technische Anpassung an Taktzeiten durch Vervielfachung der Markiermagnete und Leseeinheiten,
• – kurze Markierungslängen durch Verwendung einer Markierung auf ternärer Basis des Magnetisierungszustandes (negativ, positiv, unmagnetisiert),
• – einfach automatisierbar,
• – einfache Integration in bestehende Fertigungsabläufe.

The advantages of the invention are summarized below:

• - optically invisible marking,
• - Easy, inexpensive and quickly applied to the pipe surface mark
• Simple removal of the mark by demagnetization,
• Simple technical adaptation to cycle times by multiplication of the marking magnets and reading units,
• Short marker lengths by using a ternary-based marker of the magnetization state (negative, positive, unmagnetized),
• - easy to automate,
• - easy integration into existing production processes.

LIST OF REFERENCE NUMBERS

1

pipe

2

electromagnets

3

Circumferential marks as concentric circles

4

Circumferential markings in the form of linear longitudinal markings

5

Longitudinal markings in the tube longitudinal direction 6 .

6 '

reader

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19505513 C2 [0009]
• DE 102004051124 B3 [0012]
• DE 102008030183 B4 [0012]

Claims (8)

A method for single item tracking of hollow bodies, in particular of ferromagnetic steel tubes, which are provided for identification with a distinctive mark, characterized in that is provided for identification of the material on the tube surface with an ident mark in the form of magnetic markings of different magnetization directions. A method according to claim 1, characterized in that the identification mark is applied in multiple identical repetition on the tube. A method according to claim 1 or 2, characterized in that the magnetic markings are applied in the longitudinal and / or circumferential direction of the tube. Process according to claims 1-3, characterized in that the magnetic markings are applied in a dot-like or linear manner. Process according to claims 1-3, characterized in that the magnetic markings are applied as a barcode. Process according to claims 1-3, characterized in that the magnetic markings are applied as data matrix codes. Method according to one of claims 1-6, characterized in that for identification in addition to the marking of the tube surface with two different directions of magnetization and a mark without magnetization is used. Method according to one of claims 1-7, characterized in that the application of the magnetic marking and the readout are automated.

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