JPH11117037A - Method and device for evaluating and classifying material of cemented carbide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and rapidly evaluate the unknown material of a cemented carbide with satisfactory precision and to classify it. SOLUTION: In this method of evaluating the unknown material of a cemented carbide containing at least principal WC as hard grains and also containing Co as a binder, first, the saturation magnetization, specific gravity, and coercive force of the cemented carbide are respectively measured. Then, by utilizing the relation that the weight percentage of Co contained in a cemented carbide is proportional to the saturation magnetization of the cemented carbide, the weight percentage of the Co is evaluated. Subsequently, the weight percentage of the Co is converted to volume percentage by using the specific gravity of Co and the specific gravity of the cemented carbide, and the grain size of the hard grains is evaluated by utilizing the relation that the coercive force of the cemented carbide decreases with the increase of the volume percentage of the Co and also decreases with the increase of the grain size of the hard grains. Further, by utilizing the fact that the specific gravity of TiC which can be contained second in quantity next to WC as hard grains is as low as one-third of the specific gravity of WC or less and the relation that a change in the specific gravity of a cemented carbide mainly depends upon the changes in the contents of Co and TiC, the weight percentage of the TiC contained in the cemented carbide is evaluated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cemented carbide, and more particularly to a method and an apparatus for evaluating and classifying an unknown material of a cemented carbide.

[0002]

2. Description of the Related Art Currently, WC-Co, WC-TiC-Co, and W-Co-based cemented carbides are used in a large amount in a throw-away tip (disposable tip) for the cutting edge of a cutting tool.
Cemented carbides such as C-TiC-Ta (Nb) C-Co are in practical use.

The properties of these cemented carbides can be greatly changed by adjusting the content of Co as a binder, the particle size of carbide as hard particles, and the content of TiC. Cemented carbides of various materials are provided depending on the application. As described above, in the presence of cemented carbides of various materials, in order to accurately determine the unknown material of a cemented carbide, the hard surface of the cemented carbide sample is polished and etched, and the specimen is etched with a microscope. It is necessary to observe the tissue or chemically dissolve it for composition analysis.

[0004] By the way, cemented carbide scraps such as indexable inserts, which have been recovered as worn at the cutting tool edge as described above, are pulverized after a predetermined embrittlement treatment and reused as a powder metallurgy raw material. When reusing such cemented carbide scrap, it is essential to classify the cemented carbide scrap according to the material.

[0005]

The above-described microscopic observation and chemical composition analysis for determining the material of the cemented carbide requires a great deal of labor and time. The analysis cannot be performed non-destructively.
Therefore, conventionally, as a classification according to the material of cemented carbide scrap, it is classified very roughly by a classification based on specific gravity or a classification based on the Co content estimated from saturation magnetization, and in fact, it is classified as the same type. Actually, cemented carbide scraps can be made of different materials.

In view of such problems in the prior art,
SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus capable of non-destructively evaluating and classifying a material of a cemented carbide with a satisfactory accuracy easily and quickly.

[0007]

In the present invention, a method for evaluating an unknown material of a cemented carbide containing at least main WC as hard particles and containing Co as a binder includes a method of measuring the saturation magnetization and specific gravity of a cemented carbide. And measure the coercive force,
The weight percent of Co contained in the cemented carbide is evaluated using the relationship that the weight percent of Co is proportional to the saturation magnetization of the cemented carbide, and the specific gravity of Co and the specific gravity of the cemented carbide are used to evaluate the weight percent of Co. Weight% is converted to volume%, and the coercive force of the cemented carbide becomes the volume% of Co
The particle size of the hard particles is evaluated by utilizing the relationship that the particle size decreases with the increase of the particle size and decreases with the increase in the particle size of the hard particles.
Is less than 1/3 of the specific gravity of WC, and the change in specific gravity of the cemented carbide mainly depends on the change in the contents of Co and TiC.
Is characterized in that the weight% is evaluated.

In the present invention, the method of classifying a cemented carbide according to its material is such that each of the weight percent of Co, the particle size of hard particles and the weight percent of TiC in the cemented carbide is divided into a plurality of desired stages in advance. The material classification frame is determined, and C is evaluated by the above-described material evaluation method.
It is characterized in that the cemented carbide is classified in the material classification frame based on the material represented by the weight% of o, the particle size of the hard particles, and the weight% of TiC.

In the present invention, further, at least the main WC is contained as hard particles and Co as a binder is used.
An apparatus for evaluating an unknown material of a cemented carbide includes a saturation magnetization measuring means for measuring a saturation magnetization of a cemented carbide; a specific gravity measuring means for measuring a specific gravity of a cemented carbide; Coercive force measuring means for measuring the coercive force of: receiving the measurement data from the saturation magnetization measuring means, the specific gravity measuring means and the coercive force measuring means, and obtaining the weight% of Co contained in the cemented carbide, the particle size of the hard particles and Additional Ti as hard particles
Calculating means for evaluating the weight% of C, wherein the calculating means evaluates the weight% of Co by utilizing a relationship in which the weight% of Co contained in the cemented carbide is proportional to the saturation magnetization of the cemented carbide; C
Using the specific gravity of o and the specific gravity of the cemented carbide, the weight% of Co is converted to the volume%, and the coercive force of the cemented carbide decreases with the increase in the volume% of Co and increases in the particle size of the hard particles. The particle size of the hard particles is evaluated by utilizing the relationship of decreasing with the WC. The specific gravity of TiC, which can be contained next to WC as the hard particles, is as small as 1/3 or less of the specific gravity of WC, and the specific gravity of the cemented carbide changes. Is characterized by evaluating the weight% of TiC contained in the cemented carbide by utilizing the relationship that mainly depends on the change in the contents of Co and TiC.

In the present invention, the apparatus for classifying cemented carbide by its material further includes means for classifying cemented carbide in addition to the apparatus for evaluating the material of cemented carbide as described above. The means for classifying cemented carbides are based on the weight percent of Co in the cemented carbide, the size of the hard particles and the TiC
% Of Co, the weight% of Co, the particle size of the hard particles, and the TiC Is characterized in that the cemented carbide is classified in the material classification frame based on the material represented by the weight% of the material.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, cemented carbide used for indexable inserts for cutting tools and the like is made of WC and Co.
As an essential component, and depending on the application, TiC,
TaC, NbC and even a small amount of Zr (CN), VC, C
r ₃ C ₂ etc., and these components make up 9
Accounts for 9% by weight or more. Therefore, in the evaluation and classification of the material of the cemented carbide according to the present invention, such a fact is premised.

FIG. 1 is a block diagram showing an example of an apparatus for evaluating and classifying an unknown material of a cemented carbide as an example of an embodiment of the present invention. This device comprises a saturation magnetization measuring means 1 for measuring the saturation magnetization of a cemented carbide,
Specific gravity measuring means 2 for measuring specific gravity, coercive force measuring means 3 for measuring coercive force, Co content of cemented carbide, hard by receiving and processing measurement data measured by these measuring means Arithmetic means 4 for outputting material evaluation data on particle size and TiC content, and further classifies cemented carbide in a predetermined material classification frame based on the material evaluation data output by arithmetic means 4 Material classification means 5 is provided.

In the apparatus as shown in FIG. 1, the saturation magnetization measuring means 1 measures the saturation magnetization of a cemented carbide whose material is unknown. The measured saturation magnetization data is sent to the calculating means 4. The calculating means 4 uses the fact that the weight percent of Co contained in the cemented carbide is proportional to the saturation magnetization of the cemented carbide, and calculates the Co based on the input saturation magnetization data.
The evaluation data of the weight% is output.

At this time, generally, Co in the cemented carbide is slightly alloyed by W or the like, and its saturation magnetization is slightly smaller than 2030 gauss · cm ³ / g for pure Co. It is 90 ± 5% on the basis, and there is no problem in treating it as about 90%. Therefore, in the arithmetic means 4, Co in the cemented carbide is
Saturation magnetization per 1% by weight of 18.0 gauss · cm ³
/ G, and the input saturation magnetization data is divided by this numerical value, and the numerical value of the quotient to the first decimal place is defined as the weight% of Co in the cemented carbide.

On the other hand, the present inventors have found that the particle size of the hard particles contained in the cemented carbide has a certain correlation with the volume% of Co and the coercive force of the cemented carbide as shown in the graph of FIG. I have a relationship. In this graph, the horizontal axis represents Co% by volume, and the vertical axis represents coercive force. Curves 2a, 2b and 2c represent cemented carbides containing fine, medium and coarse hard particles, respectively, having an average particle size. In other words, in a cemented carbide, if the volume percentage of Co is constant, the value of the coercive force increases as the particle size of the hard particles decreases, while if the particle size of the hard particles is constant, the capacity of Co increases. The smaller the percentage, the greater the coercive force.

Here, what is important in the correlation shown in FIG. 2 is that the curves 2a, 2b, 2c, etc. corresponding to the respective particle sizes of the hard particles contained in the cemented carbide never cross each other. It does not overlap. That is, by knowing the Co% by volume and the coercive force of the cemented carbide, the particle size of the hard particles contained in the cemented carbide can be uniquely determined.

For example, based on the results obtained by measuring the coercive force of a cemented carbide of known material in which the particle size of hard particles and the volume percentage of Co are systematically changed in advance and plotting them on a graph, FIG.
A graph is prepared in which the particle size of the hard particles is divided into a plurality of regions such as a fine region, a medium region, and a coarse region as shown in FIG. In the graph of FIG. 3, the horizontal axis and the vertical axis represent the capacity% of Co, respectively, as in the case of FIG. 2.
And the coercive force. The region above the curve 3a indicates that the hard particles are fine, and the curves 3a and 3
b represents a medium grain, and a curve 3b
The lower region represents coarse grains.

When the calculating means 4 evaluates the particle size of the hard particles contained in the cemented carbide and outputs it as particle size evaluation data,
The calculating means 4 first converts the already calculated weight% of Co into volume% using the specific gravity data input from the specific gravity measuring means. At this time, if the specific gravity A of the cemented carbide is expressed by the following equation (1) for convenience, the alloy specific gravity A 合金 100 / C (1) The volume% of Co is expressed by the following equation (2).

Co capacity% {(specific gravity of B / Co) / C} × 100 (2) where B represents the weight% of Co, and the specific gravity of Co is 8.8.
5

The calculating means 4 plots the Co% by volume thus obtained and the coercive force data input from the coercive force measuring means 3 in a grain size region as shown in the graph of FIG. The particle size of the hard particles contained in the cemented carbide can be evaluated, and the result is output as particle size evaluation data. In FIG. 3, the curves 3 a and 3 b that define the boundaries of the grain size regions may be approximated by broken lines including a plurality of line segments so that the arithmetic unit 4 can easily process the curves.

Incidentally, WC is used as a constituent of the cemented carbide.
The components which are important next to Co and Co and affect the alloy properties and are often added next to WC as hard particles are TiC and Ta (Nb) C, and other components are added even if added. A trace amount, usually 1% by weight
It is as follows. The present inventors have investigated various types of cemented carbide currently on the market, and found that the weight% containing TiC and Ta (Nb) C was approximately in the following range.

TiC: 0 to 25% by weight TaC: 0 to 10% by weight NbC: 0 to 4% by weight In the cermet, TiC is used as main hard particles instead of WC, and usually 35% by weight or more. It contains TiC and has a specific gravity of about 6-9. On the other hand, cemented carbide has a large specific gravity of about 10 to 15. Therefore, cermets can be easily distinguished from cemented carbides only by measuring the specific gravity.

Under these circumstances, when evaluating the material of the cemented carbide from the viewpoint of the composition, it is important and desired to evaluate not only the Co content but also the TiC content. Here, the specific gravity A of the alloy containing other components is represented by the following equations (1) and (3).

Alloy specific gravity A≡100 / C (1)

[0025]

(Equation 1)

Here, Y _i represents the weight% of the i-th component, and y _i represents the specific gravity of the i-th component.

The specific gravities of the components that can be contained in the cemented carbide are as follows: WC is 15.6; Co is 8.85; TiC is 4.9.
1; TaC 14.5; NbC 7.76; TiN 5.43; ZrC 6.90; ZrN 7.09; VC.
5.36; and Cr ₃ C ₂ is 6.68. Therefore, if the weight% of Co is B and the weight% of TiC is D, the above equation (3) can be rewritten as the following equation (4).

[0028]

(Equation 2)

Here, (n-3) is the number of components excluding WC, Co and TiC in the cemented carbide.

It should be noted here that the specific gravity of TiC which may be contained in the hard metal in the range of 0 to 25% by weight as hard particles next to WC is only 1/1 / of the specific gravity of WC. While it is 3 or less, the specific gravity of TaC which may be added in the range of 0 to 10% by weight next to TiC is almost equal to the specific gravity of WC. In other words, considering a cemented carbide containing only WC and Co as a reference, if a part of WC is replaced with TiC, the specific gravity of the cemented carbide will change remarkably and become small.
Even if it is replaced by aC, the specific gravity of the cemented carbide hardly changes.

On the other hand, since NbC also has a specific gravity of 1/2 of WC, it acts to reduce the specific gravity of cemented carbide.
As described above, even if NbC is added to a cemented carbide,
Therefore, it is considered that the influence on the specific gravity of the cemented carbide is small even if NbC is included in the weight% of WC. Also, since other components are further added in a small amount and are usually 1% by weight or less, the influence of these components on the specific gravity of the cemented carbide is extremely small, and these should be included in the weight% of WC. Can be.

In consideration of such a fact, the above equation (4) can be replaced with an approximate equation such as the following equation (5) by omitting the last term.

C ≒ 6.410 + 4.889 × 10 ⁻² × B + 1.396 × 10 ⁻¹ × D (5) Therefore, the arithmetic unit 4 has already been evaluated from the saturation magnetization data from the saturation magnetization measurement unit 1. By using the weight% of Co as B in the formula (5) and using the specific gravity data from the specific gravity measuring means 2 as A in the formula (1), the unknown amount D of TiC in the formula (5) is obtained. % By weight can be evaluated.

Here, it is considered how the evaluation of the weight percentage of TiC using the equation (5) in which the last term of the equation (4) is omitted affects the accuracy. In this case, omitting the last term in the equation (4) is based on the assumption that other components other than WC, Co and TiC are not contained as components in the cemented carbide, or Is equivalent to assuming that a part by weight of the WC is also a part of the weight% of the WC.

Therefore, WC is used as the hard particles in the cemented carbide.
TaC and N, which may be included next to TiC and TiC
Consider the effect of omitting the last term in equation (4) for bC. First, as described above, TaC may be contained in the cemented carbide up to about 10% by weight. Therefore, when the cemented carbide contains 10% by weight of TaC,
The effect of omitting the last term in equation (4) is obtained as the following equation (6).

(10% by weight) × {(1 / 14.5) − (1 / 15.6)} = 4.863 × 10 ⁻² % by weight (6) Similarly, the cemented carbide contains 4% NbC. The effect of omitting the last term in equation (4) when it is included in weight% is obtained as the following equation (7).

(3% by weight) × {(1 / 7.76) − (1 / 15.6)} = 2.591 × 10 ^-1 (7) In other words, the second most in cemented carbide after WC and TiC
Both TaC and NbC that may be included
Even if the maximum is included, the end of equation (4)
By omitting the item, the evaluation value of the weight% of TiC was derived.
The input error is expressed by the following equation (8).

(4.863 × 10 ⁻² wt% + 2.591 × 10 ⁻¹ wt%) / 1.396 × 10 ⁻¹ = 2.204 wt% (8) This is because TaC and NbC are Even if it is contained at the maximum, the TiC evaluated by the equation (5)
% Means that it will only be overestimated by about 2% by weight as compared to when considering their TaC and NbC by equation (4). In addition, TaC and Nb
In practice, C is a complementary additive, and it is rare that both of them are added to the maximum at most, so in practice, T
When aC and NbC are present, the error included in the evaluation of the weight percentage of TiC is considered to be smaller than about 2 weight% because the last term in the equation (4) is omitted. Further, the components that may be further added as hard particles other than TaC and NbC, even if actually added, are small amounts of 1% by weight or less as described above. It is considered that there is almost no effect on the omission of the item in (1).

Next, considering that the weight% of Co evaluated from the saturation magnetization is used as the value of B in the equation (5),
The influence of the error contained in B on the accuracy of D, which is an evaluation value of the weight percentage of TiC, will be considered. Here, the Co weight% evaluated from the saturation magnetization actually has an error of ± 5% as described above. And in equation (5):
The effect when B includes an error of ± 5% is expressed by the following equation (9).

± 5 × 10 ⁻² × 4.889 × 10 ⁻² × B = ± 2.445 × 10 ⁻³ × B (9) Therefore, in the equation (5), the evaluation value D of the weight% of TiC is On the other hand, the error introduced by the equation (9) is obtained as the following equation (10).

− (+) (2.445 × 10 ⁻³ × B) /1.396×10 ⁻¹ = − (+) 1.7 51 × 10 ⁻² × B (10) Here, for a cutting tool Co contained in the cemented carbide used for the throw-away tip of the present invention is at most 15% by weight. Therefore, the maximum error of D in the weight% of TiC with respect to D is as follows. (+) Becomes 0.26% by weight.

From the above, it can be understood that the weight% of TiC evaluated by the arithmetic means 4 using the equations (1) and (5) has a sufficiently satisfactory accuracy.

The material classification means 5 in the apparatus shown in FIG. 1 has a material classification frame in which each of Co weight%, hard particle size and TiC weight% in the cemented carbide is divided into a plurality of desired stages in advance. The cemented carbide whose material is evaluated based on the material represented by the Co weight% evaluation data, the hard particle particle size evaluation data and the TiC weight% evaluation data output from the calculating means 4 and evaluated as Classify within the frame.

When determining the material classification frame, C
Although the classification step can be freely determined as desired for each of the evaluation items of o weight%, hard particle size, and TiC weight%, even if it is subdivided into a large number of steps beyond the accuracy of each evaluation, the detailed The classification has no meaning. Therefore, the number of classification steps in the material classification frame is preferably set to the minimum number of classification steps within a necessary and sufficient range according to the purpose.

[0045]

EXAMPLES Table 1 below shows various sample Nos. Of used throw-away tips of unknown material. 1 to No. About 15,
The results of actually evaluating those materials according to the present invention are shown.

[0046]

[Table 1]

FIG. 4 shows the evaluation criteria of the hard particle size in these samples. That is, the hard particle size is evaluated based on the particle size range shown in FIG. 3, and in the region above the curve 3a, the average particle size is about 1.2 μm.
The following fine grains are medium grains having an average grain size of about 1.2 to 2.0 μm between curves 3a and 3b, and coarse grains having an average grain size of about 2.0 μm or more in a region below curve 3b. It is. Note that in FIG. The reason why 10 is not plotted is that it is clear that this sample is not a cemented carbide but a cermet because of its specific gravity.

In order to examine the reliability of the material evaluation in Table 1, the sample No. 1, No. 4 and no. For No. 7, the structure was analyzed by microscopic observation and chemical analysis. As a result, the sample No. 1, No. 4 and N
o. 7, Co weight% is 7.8%,
6.0% and 8.2%;
1%, below 0.1% and 2.0%, and the hard particle size was medium, fine and coarse. Comparing these results with the results shown in Table 1, the material evaluation of the cemented carbide according to the present invention has a sufficiently satisfactory accuracy for practical use, and in particular, for the reuse of used throw-away chips. It will be understood that the material classification has sufficient accuracy.

[0049]

As described above, according to the present invention, a method and apparatus for evaluating and classifying an unknown material of a cemented carbide in a nondestructive manner easily and quickly with satisfactory accuracy can be achieved. Can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an apparatus for evaluating and classifying an unknown material of a cemented carbide as an example of an embodiment of the present invention.

FIG. 2 is a graph showing the correlation between Co volume%, coercive force and hard particle size among each other.

FIG. 3 is a graph for evaluating the hard particle size of a cemented carbide from the Co volume% and the coercive force.

FIG. 4 is a graph showing the results of evaluating and classifying the unknown hard particle size of a cemented carbide as an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Saturation magnetization measuring means 2 Specific gravity measuring means 3 Coercive force measuring means 4 Computing means 5 Material classification means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kobun Arisawa 1-1-1, Koyo-Kita-Kita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Norimitsu Kimoto, Koyo-Kita, Itami-shi, Hyogo 1-1-1 Chome Sumitomo Electric Industries, Ltd. Itami Works

Claims (4)

[Claims] 1. A method for evaluating an unknown material of a cemented carbide containing at least main WC as hard particles and containing Co as a binder, wherein a saturation magnetization, a specific gravity and a coercive force of the cemented carbide are measured. The weight% of Co is evaluated by using the relationship that the weight% of Co contained in the cemented carbide is proportional to the saturation magnetization of the cemented carbide, and the specific gravity of Co and the specific gravity of the cemented carbide are evaluated. Is used to convert the weight percent of Co to volume percent and the relationship that the coercive force of the cemented carbide decreases with increasing volume percent of Co and decreases with increasing grain size of the hard particles. The particle size of the hard particles is evaluated by utilizing TiC which can be contained next to WC as the hard particles.
Utilizing the relationship that the specific gravity of the cemented carbide is as small as 1/3 or less of the specific gravity of the WC and the change in the specific gravity of the cemented carbide mainly depends on the change in the contents of Co and TiC. A method for evaluating the material of a cemented carbide, characterized in that the weight% is evaluated. 2. The material classification frame in which each of the weight percent of Co, the particle size of hard particles, and the weight percent of TiC in the cemented carbide is divided into a plurality of desired stages in advance is defined. The cemented carbide is classified in the material classification frame based on the material represented by the weight% of Co, the particle size of the hard particles, and the weight% of TiC evaluated by the method of evaluating the material of the cemented carbide. A method of classifying cemented carbide according to its material. 3. An apparatus for evaluating an unknown material of a cemented carbide containing at least main WC as hard particles and containing Co as a binder, wherein a saturation magnetization for measuring a saturation magnetization of the cemented carbide is provided. Measuring means, specific gravity measuring means for measuring the specific gravity of the cemented carbide, coercive force measuring means for measuring the coercive force of the cemented carbide, the saturated magnetization measuring means, the specific gravity measuring means and the Calculating means for receiving the measurement data from the coercive force measuring means and evaluating the weight% of Co contained in the cemented carbide, the particle size of the hard particles, and the weight% of additional TiC as the hard particles; The calculating means evaluates the weight percent of Co by using the relationship that the weight percent of Co contained in the cemented carbide is proportional to the saturation magnetization of the cemented carbide, and the calculating means determines the specific gravity of Co and the cemented carbide. Combination Using the specific gravity of gold to convert the weight percent of Co to volume percent, the coercivity of the cemented carbide decreases with increasing volume percent of Co and increases with the particle size of the hard particles. Evaluating the particle size of the hard particles by utilizing the relationship of decreasing, the calculating means further calculates that the specific gravity of TiC which can be contained next to WC as the hard particles is as small as 1/3 or less of the specific gravity of WC. The change in specific gravity of cemented carbide is mainly due to Co
An apparatus for evaluating the material of a cemented carbide, characterized in that the weight% of TiC contained in the cemented carbide is evaluated using the relationship that the cemented carbide depends on the change in the TiC content. 4. The apparatus for classifying a cemented carbide according to claim 3, further comprising a unit for classifying the cemented carbide, wherein the unit for classifying the cemented carbide is provided in the cemented carbide. 4. A material classification frame in which each of the weight% of Co, the particle size of hard particles, and the weight% of TiC is divided into a desired plurality of stages in advance, and the weight% of Co evaluated by the apparatus according to claim 3; An apparatus for classifying a cemented carbide according to its material, wherein the cemented carbide is classified in the material classification frame based on a material represented by a particle size of hard particles and a weight% of TiC.