WO2015081352A1

WO2015081352A1 - Method for hard metal body characterization

Info

Publication number: WO2015081352A1
Application number: PCT/AT2014/000212
Authority: WO
Inventors: Peter Fink; Johannes Glätzle; Rolf KÖSTERS; Ralph USELDINGER
Original assignee: Ceratizit Austria Gesellschaft M.B.H.
Priority date: 2013-12-02
Filing date: 2014-12-01
Publication date: 2015-06-11
Also published as: EP3077337A1; AT14087U1

Abstract

A method for hard metal body characterization is provided comprising the steps: (S1) positioning a micromagnetic measuring head (6) on a hard metal body (20) to be characterized, wherein the measuring head (6) has at least: an exciter unit (8) with an exciter magnet (81) and a low frequency generator (82) for generating a low-frequency magnetic excitation alternating field; an excitation magnetic field sensor (7) for detecting the magnetic alternating field that has been generated; and an induction sensor (9) with a coil arrangement; (S2) application of a low-frequency magnetic alternating field using the excitation unit (8) and detection of the signals from the excitation magnetic field sensor (7) and the induction sensor (9); and (S3) evaluation and (S4) assignment of the detected signals to one hard metal class, which is characterized at least by a binder content range and a particle size range of the hard material particles, of a plurality of hard metal classes (HM1, HM2, HM3).

Description

PROCESS FOR HARD METAL BODY CHARACTERIZATION

The present invention relates to a method for

Carbide body characterization and a

Hard metal characterization device and uses of such.

Carbide components are used in many applications, where both a relatively high hardness of the component and high wear resistance are required. The application areas of

Carbide extend over many different technical

Areas of application, i.a. Tools for metalworking,

especially metal cutting, the paper or

Plastic processing, tools for wood or stone processing, forming tools for various purposes and much more.

In the case of cemented carbide, hard-material particles, which may be predominantly formed by tungsten carbide (WC), are present in a matrix of a ductile binder, which usually comprises cobalt (Co), iron (Fe) and / or nickel (Ni), in particular by a combination of one or more of cobalt, iron and nickel may be formed, in particular by cobalt embedded. In addition to tungsten carbide, if necessary, further hard material particles,

in particular cubic carbides of one or more of the elements of Groups IV B, VB and VI B of the Periodic Table of the Elements, also be present in minor proportions. Furthermore, other elements, in particular tungsten and / or chromium, may be present in dissolved form in the binder even in small amounts. Carbide is most frequently used, in which the binder consists at least essentially of cobalt, if necessary with further elements dissolved in small amounts therein, in particular tungsten and / or chromium, and the hard material particles are formed at least essentially by tungsten carbide, wherein Comparison to the proportion of tungsten carbide in percent by weight - small amounts of said cubic carbides and, if necessary, other substances may be present in small amounts. Due to the combination of the ductile binder embedded in it

Hard material particles have carbide unique material properties.

In particular, the hard material particles provide a high hardness of the material, whereas the binder gives the cemented carbide a certain toughness. In this way, with cemented carbide the conflict of objectives between a hard as possible and thus abrasion resistant, but it brittle material and on the other hand a tough and thus impact resistant, but not so hard material for a variety of applications can be satisfactorily solved.

Today, the properties of the carbide are very specifically adapted to the respective application. For this purpose, in particular, the percentage of binder is varied over a wide range, to achieve rather tough carbide, a larger binder content is used and to achieve greater wear resistance, a lower binder content. In addition, the grain size of the hard material particles, in particular of the hexagonal tungsten carbide, is adjusted to the desired

To obtain material properties. The grain size is controlled in particular by the particle size of the starting material used and the addition of the aforementioned cubic carbides as grain growth inhibitors in the powder metallurgy production of the hard metal.

Due to the very large differences in particular the binder content and the grain size of the hard material particles, the different hard metals have a relatively wide range of different properties. For a relatively coarse but already sufficient classification for many applications, it is customary to subdivide according to the parameters binder content (in

Weight percent), average particle size of the hard material particles (in particular tungsten carbide) and resulting hardness (usually measured as Vickers hardness, eg HV30). A classification into a specific carbide class can then be made depending on the value ranges of these parameters. An even more accurate subdivision, for example, taking into account the exact proportions of different cubic carbides, can be omitted for a relatively large number of purposes. In a determination of the working group carbide (Fachverband Pulvermetallurgie) to the particle size classes takes place with respect to the middle

Grain size of the WC grains is a classification e.g. in the following classes:

Due to commodity price development and below general

In terms of sustainability, there has recently been a trend towards increased use of recycled material in the

Carbide production revealed. Thereby, used cemented carbide bodies in which e.g. a functional area is worn out, and their material is re-used in a carbide

Reprocessed manufacturing process. In order to ensure a very high quality of the carbide to be produced when using such recycled material, it is necessary to classify and sort the recycled material according to the criteria described above (binder metal content, grain size, hardness), to separate the different

To operate carbide classes.

US 4,466,945 describes a method for sorting

Carbide recycling material by binder content and grain size of

Tungsten carbide grains.

Since a direct measurement of e.g. The binder content, grain size and hardness of hard metal is very complex and sometimes associated with difficulties, it is common in the carbide industry, an indirect

To apply measurement methodology. The binder metals used in hard metal Co, Fe, Ni or their alloys, in particular Co, have ferromagnetic properties and also the carbide shows

ferromagnetic properties. Due to the ferromagnetic

Properties undergoes the magnetic flux density B in the hard metal as a function of the applied magnetic field strength H of an applied

Magnetic field a hysteresis loop, as it is generally known from ferromagnetic materials. The hysteresis loop can be characterized by certain properties, in particular the coercive field strength H _c , the magnetic remanence BR and the saturation magnetization 4πσ. The saturation magnetization 4πσ and the coercive force H _c correlate with the characteristic properties of the hard metal, ie in particular the binder content (ie the proportion of the ferromagnetic binder) and the grain size of the hard material particles, ie in particular the WC grains. The hardness of the carbide is in turn with the

Binder content and grain size in particular of the WC grains in

Context.

In practice, in the carbide industry, it is therefore common to

Characterization of an (unknown) hard metal to determine the coercive force H _c and the saturation magnetization 4πσ and infer from these measurements on the binder content and the grain size of the hard material particles. Furthermore, the hardness of the hard metal can already be deduced to some extent in this way, so that the detection of the

Coercive field strength H _c and the saturation magnetization 4πσ already allows a classification of the hard metal. To a closer

Subclassification to make or the conclusions of the measured coercive force H _c and the measured

To confirm saturation magnetization Ana, a hardness test (in particular a Vickers hardness measurement) is often additionally carried out in practice and / or, if appropriate, a metallurgical finish is made for the microscopic examination of the grain size and the microstructure. In order to measure the coercive force Hc, according to the conventional methods, it is necessary to produce a fragment of the hard metal and to introduce it into a special measuring device. Performing a Vickers hardness measurement and The preparation of a metallurgical cut are very complex and not suitable for continuous measurement, as they are in particular for a

Classification and sorting of carbide recycling material is desirable.

EP 0 595 1 17 B1 describes a method for examining a test specimen, which is formed from a ferrous material with cementite fins in a ferrite matrix, with a micromagnetic measuring head. Carbide is usually used in a powder metallurgy

Manufacturing process in which powdered starting material is pressed and then sintered in a liquid-phase sintering process to form a stable and dense hard metal body. It is particularly important in this process to adjust the resulting carbon content in the cemented carbide very accurately to the desired

To achieve material properties. If the carbon content is too low, there is the danger of the formation of so-called η-phase, undesired metal carbides of the form Me ₆ C, Me- ₂ C, with Me = Co and / or W, whose

Presence has a very adverse effect on the mechanical properties of the carbide. Excessively high carbon content risks carbon deposits, which also have very adverse effects on the mechanical properties of the cemented carbide. Of the

Carbon content in the hard metal is also reflected, at least in the saturation magnetization 4πσ, which is why also for checking or monitoring the highest 11 u ng sp cess, i. for quality assurance, samples from respective manufacturing batches relating to this physical

Parameters are examined. Also in this case, the conventionally practiced analysis is very laborious and requires the destruction of the samples. It is an object of the present invention to characterize

Carbide bodies, especially in carbide recycling, to facilitate and to simplify the quality assurance of the carbide production process. The object is achieved by a method for hard metal body characterization according to claim 1. Advantageous developments are specified in the dependent claims.

The process for hard metal body characterization comprises the following steps:

Examining a carbide body to be characterized with a micromagnetic measuring head, wherein the measuring head comprises at least: an exciter unit with an excitation magnet and a

Low frequency generator for generating a low frequency magnetic excitation alternating field;

an excitation magnetic field sensor for detecting the generated alternating magnetic field; and

an induction sensor with a coil assembly;

• Applying a low-frequency alternating magnetic field with the

Exciter unit and detecting the signals of

Excitation magnetic field sensor and induction sensor, and

• Evaluation and assignment of the recorded signals to one

Hard metal class, which is characterized at least by a binder content range and a grain size range of the hard material particles, of a plurality of carbide classes.

By the use of the micromagnetic measuring head, which has the exciter unit, the excitation magnetic field sensor and the induction sensor for carbide body characterization, a simple measurement is made possible, with a classification of carbide at least with respect to the

Binder content and grain size of the hard particles can be done without complex and time-consuming measurement methods must be used. In this way, for example, carbide recycling material, the properties of which are not initially known in particular with respect to binder content and grain size of the hard material particles are quickly and inexpensively characterized and sorted into different carbide classes, which can then be fed separately each a recycling process. In this way, in a simple and cost-effective manner, a very high quality of the Carbide provided recycling process resulting in particular, even if in the recycling process no complete chemical

Processing into individual components takes place, as e.g. in the known Zn recycling process of carbide is the case. In addition to a characterization in terms of binder content and grain size of

Hard material particles may in particular preferably also have a

Characterization regarding the hardness of the hard metal done.

The object is also achieved by a method for hard metal body characterization according to claim 2. Advantageous developments are specified in the dependent claims.

The process for hard metal body characterization comprises the following steps:

Examine a produced carbide body with a

micromagnetic measuring head, wherein the measuring head comprises at least: an exciter unit with an exciter magnet and a

an induction sensor with a coil assembly;

Applying a low-frequency alternating magnetic field with the excitation unit and detecting the signals of the excitation magnetic field sensor and the induction sensor,

• Evaluating and assigning the detected signals to a hard metal class, which is characterized by at least one carbon content of the hard metal

is characterized by a plurality of carbide classes. By using the micromagnetic measuring head, which has the exciting unit, the excitation magnetic field sensor and the induction sensor, for hard metal body characterization to evaluate the manufacturing process, the hard metal manufacturing process, in which the binder content and the resulting grain size of the hard material particles in the hard metal basically are known to be checked in a simple and cost-effective manner with regard to the carbon content of the cemented carbide, so that a control of the sintering process is possible. The control can be particularly non-destructive and as an integrated step in the

Manufacturing process done.

According to a further development, the hard metal body is assigned

(i) a first class characterized by a desired carbon content of the cemented carbide,

(ii) a second class that is too low

Carbon content of the carbide is marked, or

(iii) a third class characterized by too high carbon content of the cemented carbide. In this case, the hard metal body (and further carbide body of the same manufacturing batch) can be selectively fed to a post-treatment, if too low a carbon content or too high

Carbon content is present. The first class can in particular by a certain range of carbon content by one

Target carbon content to be determined.

According to a further development, the hard metal body is fed to a post-treatment when it has been divided into the second class or the third class. In this case, even if initially too low or too high carbon content is present, a desired high quality of the

Ensured manufacturing process resulting carbide body.

According to a further development, a high-frequency generator unit is provided, and the method comprises the step of: applying one to the

Excitation alternating field of higher frequency magnetic alternating field for

Generation of eddy current induced magnetic fields. In this case, the carbide body characterization may also be based on that of the

Permeability and the conductivity of the carbide body dependent

Eddy current impedance, which is a particularly good classification and / or assessment of the manufacturing process. In this case, the higher-frequency magnetic alternating field preferably has a lower amplitude than the excitation alternating field. According to a development, the detected signals are evaluated to determine the overlay permeability. Also an evaluation of the

Overlay permeability allows a particularly advantageous

Classification and / or control of the manufacturing process. According to an alternative or additional development, the detected signals are evaluated to determine the magnetic field

Barkhausen noise. Also, the evaluation of the Barkhausen noise allows an advantageous classification and / or control of

H ighlighting.

The object is also achieved by a hard metal characterization device according to claim 9. Advantageous developments are specified in the dependent claims. The hard metal characterization device has an evaluation electronics and a measuring head, wherein the measuring head comprises: an excitation unit with an excitation magnet and a low-frequency generator for generating a low-frequency excitation magnetic field, a

Excitation magnetic field sensor for detecting the excitation magnetic field, and an induction sensor with a coil assembly. The evaluation electronics is designed to detect a signal of the excitation magnetic field sensor and a signal of the induction sensor, to process it electronically and to output at least one physical measurement variable representative of a classification of the cemented carbide on a user interface.

Compared with a conventional carbide body characterization method which requires a complicated and time-consuming measuring technique, the carbide characterization apparatus enables advantageous nondestructive, rapid and inexpensive characterization of hard metal bodies, in particular for classification according to a

Binder content and a grain size of the hard material particles and / or to

Verification of a carbide manufacturing process. According to a development, the evaluation electronics are designed to output at least one physical measurement variable representative of a classification of the hard metal, at least with respect to a particle size of the hard material particles and a binder content. In this case, a simple and inexpensive classification of carbide bodies is made possible

can be used in particular in a recycling of hard metal material.

According to a development, the evaluation electronics are designed to provide at least one for a classification of the hard metal with respect to the

Carbon content represent representative physical measure. The at least one physical measurand may be e.g. especially with known binder content and / or known grain size of the hard material particles for the carbon content of the hard metal be representative. In this case, the cemented carbide characterization device allows easy and inexpensive control of the hard metal fabrication process.

According to one embodiment, a high-frequency generator unit for generating a relative to the excitation alternating field higher-frequency magnetic alternating field for generating further eddy current induced

Magnetic fields provided so that one of the permeability and the

Conductivity of the hard metal body dependent eddy current impedance is detected. In this case, a particularly advantageous characterization of

Hard metal bodies in particular by binder content and grain size of

Hard material particles allows.

According to a development, the excitation magnetic field sensor has a Hall sensor. The object is also achieved by using a previously described hard metal characterization device for classifying

Carbide bodies dissolved at least with respect to binder content and grain size of the hard particles.

The object is further achieved by use of a previously

described hard metal characterization device for checking a manufacturing process of a cemented carbide body solved. In this case, a check of the carbon content of the hard metal body is preferably carried out.

Further advantages and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. From the figures show:

1 shows a schematic representation of a hard metal characterization device according to an embodiment; 2 is a schematic block diagram for explaining a

Method for carbide characterization according to a first embodiment; and

3 is a schematic block diagram for explaining a

Method for carbide characterization according to a second embodiment.

Embodiment

First, an embodiment of a

Hard metal characterization device 1 with reference to Fig. 1 described in more detail.

The carbide characterization device 1 has a control unit 2 with evaluation electronics 3 whose function will be described in more detail below. The transmitter 3 is connected via a data line 4 with a

User interface 5 connected, for example, by a display, In particular, a screen can be formed. The evaluation 3 and the control unit 2 may, for example, at least partially by a

be implemented accordingly equipped computer. The hard metal characterization device 1 also has a

Measuring head 6, which is designed for a study of hard metal bodies. In Fig. 1 is an exemplary hard metal body 20 in the form of a

Hard metal plate shown. However, the measuring head 6 is designed to examine carbide bodies of different size and shape. The measuring head 6 is shown schematically in dashed lines in Fig. 1.

The measuring head 6 has an excitation unit 8 with an exciter magnet 81 and a low-frequency generator 82 for generating a low-frequency magnetic excitation alternating field, as shown schematically in FIG. 1. In this case, the excitation magnet 81 has a magnetic yoke 81 1 and an exciter coil 812 encompassing the yoke 81 1 at least in regions, which can be driven by the low-frequency generator 82. Of the

Low frequency generator 82 is connected via (not shown lines) to the control unit 2, so that the control unit 2 the

Low frequency generator 82 and thus the excitation unit 8 can control. The yoke 81 1 has a substantially U-shaped configuration with two

Thigh 81 1 a on. With the low-frequency generator 82 can be generated via the excitation coil 812 in the yoke 81 1 an excitation magnetic field with which the examined hard metal body 20 on the legs 81 1 a of the yoke 81 1 can be acted upon. Although in Fig. 1 schematically a

Exciter coil 812 is shown, which surrounds the yoke 81 1 in a central region, other suitable arrangements are possible. For example, can also be two interconnected part-exciting coils each on the

Legs 81 are arranged 1a of the yoke 81 1.

The measuring head 6 also has an excitation magnetic field sensor 7 for

Detecting the generated excitation magnetic field. In the embodiment, the excitation magnetic field sensor 7 is interposed by one between the

Legs 81 1 a of the yoke 81 1 arranged Hall sensor formed. Of the Excitation magnetic field sensor 7 is connected via lines not shown to the control unit 2, so that the transmitter 3 can detect and evaluate a signal of the excitation magnetic field sensor 7. Of the

Excitation magnetic field sensor 7 is arranged to locally the

to measure the dominant tangential component of the excitation magnetic field strength.

In the measuring head 6 is also an induction sensor 9 with a

Coil arrangement is provided, which is also disposed between the legs 81 1 a of the yoke 81 1, as shown schematically in Fig. 1. Of the

Induction sensor 9 may e.g. in a conventional manner, two core parts having a coupling gap and a Rückschlussspalt, wherein on the respective core parts in each case an induction coil is arranged. The two induction coils are via lines (not shown) with the

Transmitter 3 of the control unit 2 connected. The coupling gap of the induction sensor 9 is arranged such that it can be brought close to the surface of the hard metal to be examined. The width of the

Einkoppelspaltes is preferably selected such that it is in the range of the dimension of microstructures in hard metal bodies to be examined. Preferably, the induction sensor 9 is surrounded except in the region of the coupling-in gap of a shielding to keep interference as low as possible. The transmitter 3, the output voltage of the

Detecting and evaluating induction sensors 9. As also shown schematically in FIG. 1, the hard metal characterizing device 1 further has a high frequency generator unit 11 for generating a magnetic field having a higher frequency than the excitation magnetic field for generating eddy current induced magnetic fields in the hard metal body 20 to be examined. In the example shown schematically in Fig. 1, the high-frequency generator unit 1 1, a coil assembly 1 1 1, which is also integrated in the measuring head 6 is formed. The high-frequency generator unit 11 is designed to generate an alternating magnetic field having a significantly higher frequency than the excitation magnetic field, for example by a factor of 100 higher, and at a much lower amplitude than that

Excitation magnetic field, so that the high-frequency magnetic

Alternating field is superimposed on the excitation magnetic field. The

High frequency generator unit 11 is also not shown above

Connecting lines connected to the control unit 2 and can be controlled via this. Although in Fig. 1 schematically a separate coil assembly 1 1 1 between the legs 81 1 a of the yoke 81 1 is shown, it is e.g. also possible to form the high frequency generator unit 11 differently or

to arrange. In particular, it is e.g. also possible to arrange one or more coils on the yoke 81 1 and the legs 81 1 a of the yoke 81 1 in order to provide the higher-frequency magnetic field to be superimposed.

The control unit 2 with the transmitter 3 is so with the

connected to various components of the measuring head 6, that on the exciter unit 8, a low-frequency alternating magnetic field can be generated by the high-frequency generator unit 1 1 a

higher-frequency alternating magnetic field is superimposed, and the signals of the excitation magnetic field sensor 7 and the induction sensor. 9

especially time-resolved can be detected and evaluated.

The evaluation 3 is designed to evaluate the received signals in a variety of ways. For this purpose, the

Evaluation electronics 3, in particular various filter elements,

Amplifier elements and / or band-pass elements and memory elements for storing the received or evaluated signals. The evaluation electronics 3 preferably has e.g. in particular, one or more A / D converter, so that the described components can be preferably at least partially implemented as software. The evaluation electronics 3 can e.g. from the detected signals the

Barkhausen noise signal of magnetic Barkhausen noise

determine, determine the eddy current impedance, in particular spatially resolved, evaluate the overlay permeability and / or perform a harmonic analysis. The exact implementation of this evaluation is described below not described in detail. A possible evaluation of such signals is described in detail, for example, in the EP 0 595 1 17 B1 already mentioned in the introduction to the description and a detailed description of the possible

Evaluations of the signals can be found e.g. in the dissertation "Development of metrological modules for multivariate electromagnetic

Material Characterization and Testing "by K. Szielasko, Saarland University, Saarbrücken 2009, published on 26.08.2009.

According to a first embodiment schematically shown in Fig. 2, the described hard metal characterization device is the

Characterization of carbide used at least in relation to the binder content and the mean grain size of the hard material particles. In addition, a characterization with regard to the hardness can preferably also be carried out. In this use, the hard metal characterization device is used to classify hard metal bodies whose physical properties, such as, in particular, the binder content and the

Grain size of the hard material particles, are not initially known, as e.g.

especially when sorting hard metal recycling material is often the case.

In the method for hard metal body characterization according to the first embodiment, an assignment of characteristic signals, which were evaluated by the evaluation electronics 3, initially occurs

different carbide classes, which differ in particular in their binder content and / or the grain size of the hard material particles and / or the hardness. For this purpose, first a reference measurement with different reference carbide bodies, their binder content and grain size of the

Hard material particles, in particular the average particle size of WC-Kömern, and if necessary. Hardness are known and correspond to the typical representatives of the different carbide classes.

The number of carbide classes to be differentiated may differ depending on the respective purpose of the characterization, eg it may be sufficient for a classification, a classification according to the Grain size classes N (nano), U (ultra-fine), S (submicron), F (fine),

M (medium), C (coarse) and E (extra coarse) of the WC grains common in the cemented carbide industry, and e.g. three different ranges of binder content, e.g. B1 (<8% by weight), B2 (between 8% by weight and

12% by weight) and B3 (> 12% by weight).

In one example, measurements are first carried out with carbide bodies representative of the respective carbide classes and the

Differences in the evaluated signals between the respective ones

Carbide grades are determined. The different grades of carbide show in the evaluated sizes, in particular in the

Barkhausen noise curves, in the eddy current impedance, in one

Harmonic analysis and / or overlay permeability, characteristic properties for each carbide grade. The selection of one or more concrete physical parameters that are used for the characterization can take place differently depending on the desired accuracy of the classification. For example, it is possible to evaluate the detected signals to determine the magnetic Barkhausen noise or overlay permeability. As characteristic values, e.g. certain maximum values, peak heights, peak widths or the like are evaluated.

After the initial identification of the characteristic features which are to be used for the classification in hard metal classes, and based on the reference carbide bodies, an assignment of such characteristics was made to the individual carbide classes, then carbide body with initially unknown physical properties, such as unknown binder content and unknown mean grain size of the hard material particles are examined and classified by the method for hard metal body characterization according to the first embodiment.

For this purpose, in a first step S1, the micromagnetic measuring head 6 is placed on the hard metal body 20 to be examined. For this example, the Measuring head 6 placed on the hard metal body 20. As is shown schematically in FIG. 2, in a step S2 a low-frequency alternating magnetic field is applied to the excitation unit 8 and the signals of the

Excitation magnetic field sensor 7 and the induction sensor 9 are detected by the transmitter 3. In this case, it is also preferable in a step S2 'to apply a higher-frequency magnetic alternating field of lower amplitude with respect to the excitation alternating field for generating eddy current-induced magnetic fields with the magnetic field

High-frequency generator unit 11, while the transmitter 3 detects the signals of the excitation magnetic field sensor 7 and the induction sensor 9.

In a subsequent step S3 evaluates the evaluation 3, the detected signals of the excitation magnetic field sensor 7 and the

Induction sensor 9 off. By comparing the evaluated signals with the corresponding signals of the previously examined reference carbide body, in a step S4, an assignment of the detected and evaluated signals to one of the determined carbide classes HM1, HM2, HM3, at least by a binder content range and a

WC grain size range are characterized.

In this way, it is thus possible to non-destructively perform a classification of unknown hard metal bodies according to carbide classes, which are characterized by at least a binder content range and a WC grain size range by a measuring method with the carbide characterization device 1.

The described carbide characterization method thus enables a simple and cost-effective sorting of e.g.

Carbide recycling material according to various carbide grades, so that the carbide bodies can be sorted according to carbide grades and fed into the recycling process, thus ensuring a high quality of the recycling process. In a second exemplary embodiment shown schematically in FIG. 3, the hard-metal characterization device 1 is used to check a

Manufacturing process used by carbide bodies. The method for hard metal body characterization according to the second embodiment is different from the first embodiment described above in that it is not for classifying a

Carbide body is used, the binder content and grain size of the hard particles is initially unknown, but to verify the manufacturing process of hard metal bodies, in which the binder content and the grain size range of the hard material particles is basically known.

According to the second embodiment is also a

Based on reference measurement of carbide bodies. In a

Reference measurement is at least one hard metal body with a

predetermined binder content and a predetermined particle size range of the hard material particles, in particular of WC grains, which also has a desired target carbon content of the hard metal, examined with the previously described hard metal characterization device 1. Furthermore, in each case at least one comparison hard metal body with the same binder content and particle size range of the hard material particles, but too low carbon content, and at least one comparative hard metal body with the same binder content and particle size range of the hard material particles, but too high carbon content, are examined. As in the embodiment described above, characteristic features in the detected and evaluated with the evaluation unit 3 signals of the excitation magnetic field sensor 7 and the

Induction sensor 9, which are suitable for distinguishing the target carbon content, the low carbon content and the high carbon content of the hard metal selected. In particular, this is characterized by at least one physical quantity for distinguishing a first class K1, which is characterized by the desired carbon content, a second class K2, which is characterized by a low carbon content, and a third class, which is characterized by a low carbon content is, selected. In turn, in particular, an evaluation of the Signals for determining the superposition permeability, the Barkhausen noise, the eddy current impedance and / or a

Harmonic analysis done. There may be e.g. again a peak height, a peak width and / or other characteristic properties of the signals are used.

After this reference measurement has been carried out, according to the second embodiment, a check is made on the production process of cemented carbide with the following steps.

In a step S1 1, a placing of the micromagnetic

Measuring head 6 on a hard metal body 20 from the production batch to be examined. In a step S12, a low-frequency alternating magnetic field is applied with the excitation unit 8 and the signals of the

Excitation magnetic field sensor 7 and the induction sensor 9 are detected. According to a preferred embodiment, in a step S12 'with the high frequency generator unit 1 1 also applying a relation to the excitation alternating field higher frequency magnetic alternating field for generating eddy current induced magnetic fields and the signals of the excitation magnetic field sensor 7 and the induction sensor 9 are detected.

In a step S13, the evaluation unit 3 evaluates the detected signals of the excitation magnetic field sensor 7 and of the induction sensor 9. Based on the previously carried out reference measurements, an assignment of the hard metal body 20 to a first class K1, which is characterized by a desired carbon content, a second class K2, which is characterized by a too low carbon content, or a third class K3, takes place in a step S14 , which is characterized by a high carbon content. The assignment is based on whether the evaluated signals have the characteristics characteristic of the first class K1, the second class K2 or the third class K3. If the cemented carbide body 20 is assigned due to the measurement results of the first class K1, which is characterized by the target carbon content or a target carbon content range, the process ends in this step and the manufacturing process of the corresponding batch is judged to be satisfactory. However, if an assignment is made to the class K2, which is characterized by a low carbon content, the carbide body of the batch in a step S15 of

Post-treatment NB1 supplied to increase the carbon content. If an assignment in the class K3 takes place, due to a too low

Carbon content is characterized, the carbide bodies of the batch in step S15, however, a post-treatment NB2 supplied to reduce the carbon content.

The described method and the described use of the

Carbide characterization device thus enable a

Non-destructive testing of the carbide production process in a simple and cost-effective manner.

Claims

claims

Method for hard metal body characterization, with the steps:

(51) placing a micromagnetic measuring head (6) on a hard metal body (20) to be characterized, wherein the measuring head (6) has at least:

an exciter unit (8) having an exciter magnet (81) and a low frequency generator (82) for generating a low frequency magnetic excitation alternating field;

an excitation magnetic field sensor (7) for detecting the generated alternating magnetic field; and

an induction sensor (9) having a coil arrangement;

(52) applying a low - frequency alternating magnetic field with the excitation unit (8) and detecting the signals of the

Excitation magnetic field sensor (7) and the induction sensor (9), and

(53) evaluate and (S4) assign the detected signals to a

Hard metal class, which is characterized at least by a binder content range and a grain size range of the hard material particles, of a plurality of carbide classes (HM1, HM2, HM3).

Method for hard metal body characterization, with the steps:

(51 1) placing a micromagnetic measuring head (6) on a produced cemented carbide body (20), wherein the measuring head has at least:

an induction sensor (9) having a coil arrangement;

(512) applying a low frequency alternating magnetic field with the exciter unit (8) and detecting the signals of the

Excitation magnetic field sensor (7) and the induction sensor (9); (S13) evaluating and (S14) assigning the detected signals to a hard metal class characterized by at least one carbon content of the hard metal, of a plurality of

Hard metal classes (K1, K2, K3).

The method of claim 2, wherein the evaluating and associating includes:

Assigning the hard metal body (20) to

(iv) a first class (K1) characterized by a target carbon content of the cemented carbide,

(v) a second class (K2) that is too low

Carbon content of the carbide is marked, or

(vi) a third class (K3) that is too high

Carbon content of the carbide is marked.

The method of claim 3, wherein the method further comprises the step (S15)

Feeding the cemented carbide body (20) to a

Aftertreatment (NB1, NB2) if it is divided into second grade (K2) or third grade (K3).

Method according to one of the preceding claims, further comprising a high-frequency generator unit (1 1) and the method comprises the step:

(S2 \ S12 ') applying a relative to the excitation alternating field higher frequency magnetic alternating field for the generation of eddy current induced magnetic fields.

The method of claim 5, wherein the higher frequency alternating magnetic field has a lower amplitude than the excitation alternating field.

Method according to Claim 5 or 6, comprising the step of evaluating the detected signals for determining the overlay permeability.

8. The method according to any one of the preceding claims with the step: evaluating the detected signals to determine the magnetic Barkhausen noise. 9. Hard metal characterization device (1) with:

an evaluation (3) and

a measuring head (6), comprising

an exciter unit (8) having an excitation magnet (81) and a low-frequency generator (82) for generating a low-frequency excitation magnetic field,

an excitation magnetic field sensor (7) for detecting the

Excitation magnetic field, and

an induction sensor (9) with a coil arrangement,

wherein the evaluation electronics (3) is adapted to a signal of the excitation magnetic field sensor (7) and a signal of the

Induction sensors (9) to detect, electronically process and output at least one representative of a classification of the hard metal physical measurement at a user interface. 10. hard metal characterization device according to claim 9, wherein the evaluation electronics (3) is adapted to output at least one for a classification of the hard metal at least with respect to a grain size of the hard material particles and a binder content representative physical quantity.

1 1. Hard metal characterization device according to claim 9, wherein the evaluation electronics (3) is designed to output at least one physical measurement variable representative of a classification of the cemented carbide with respect to the carbon content.

12. Hard metal characterization device according to one of claims 9 to 1 1, comprising a high-frequency generator unit (1 1) for generating a relative to the excitation alternating field higher-frequency magnetic alternating field for generating eddy current-induced magnetic fields.

13. A hard metal characterization apparatus according to any one of claims 9 to 12, wherein the excitation magnetic field sensor (7) comprises a Hall sensor.

Use of a hard metal characterization device (1) according to one of claims 9 to 13 for the classification of

Hard metal bodies (20) at least in relation to binder content and grain size of the hard material particles.

Use of a hard metal characterization device (1) according to one of claims 9 to 13 for checking a

Manufacturing process of a hard metal body (20).

16. Use according to claim 15, wherein a review of a

Carbon content of the hard metal body (20) takes place.