JPH03251736A - Measuring method of degree of bonding of vitrified superabrasive wheel - Google Patents

Abstract

PURPOSE:To obtain correctly a grinding effect as expected in a non-destructive manner before use for grinding, by measuring waveforms of indentations of the outer peripheral surface of a superabrasive wheel, by determining the number of peaks due to a superabrasive at each prescribed depth and by determining the degree of bonding of the wheel from the depth showing the maximum number of peaks. CONSTITUTION:The outer peripheral surface of a vitrified superabrasive wheel which is prepared by bonding a superabrasive in the form of a thin layer on the outer peripheral surface of a wheel is used for cutting. The indentations of the surface thereof are measured all over the outer peripheral surface being used, by a displacement gage, and waveforms showing a change thereof are determined. Then, a cutting edge interval which is an average interval between peaks due to the superabrasive existing in a prescribed depth from the surface is determined. Besides, a depth Di from the surface at which the number of cutting edges is the maximum at which the number of peaks is the maximum is determined. The cutting edge interval and the depth at which the number of cutting edges is the maximum become small as the degree of bonding varies from F to L, and a definite orderly relationship is found between these interval and depth and the degree of bonding. By preparing a graph as to wheels having various degrees of bonding known already, beforehand, by using this relationship, the degree of bonding can be determined as to a wheel of which the degree of bonding is unknown, in a nondestructive manner, before it is used for grinding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a novel method for measuring the degree of bonding of a vitrified superabrasive wheel.

[Prior art and its problems]

The degree of bonding is important for various types of wheels conventionally used for grinding metal materials, and they are required to have a sufficient degree of bonding so that the abrasive grains do not fall off during operation and exhibit the expected grinding effect. Unlike general whetstones that use alumina or silicon carbide, which are known by the trade names Alundum and Carborundum, we use hard and expensive so-called super-abrasives made of natural or synthetic diamond or hexagonal boron nitride (CBN). In the case of a superabrasive wheel that is bonded with a binder such as vitrified bond, it is required to have a particularly appropriate degree of bonding so that the expensive superabrasive grains, which are hard and can be used for a long time, do not fall off early. be done.

Conventionally, an in-line bonding tester has been widely used to measure the bonding degree of general grindstones. This is a method in which a bifurcated bit is rotated 120 @ on the surface of the sample to be used, and the depth of the bit's penetration (unit: am) is measured. Take the average value. The degree of bonding of general grindstones is evaluated using the outer Rockwell hardness (H'') or the dynamic elastic modulus measurement method using a sonic comparator or ultrasonic waves.

On the other hand, in the case of the above-mentioned superabrasive wheels, there is no suitable measuring method for directly measuring the degree of bonding. Generally, in the case of superabrasive wheels, because they are expensive, superabrasive grains are only bonded to the outer peripheral surface of the wheel used for grinding in a thin layer of 1 to 3 mm along with a binder. A portion of the core is constructed of another material, such as metal. For such a thin and expensive rim of superabrasive grain, it is impossible to use the above-mentioned ultra-thin type measuring machine that measures the depth of penetration by gouging it out with a bit.
Also, even if you use a hardness measuring tool for extremely hard superabrasive grains,
It is damaged and the hardness cannot be measured. Even if it were possible to measure it, reliable data would not be obtained. In addition, since the measurement method using ultrasonic waves requires a certain amount of thickness or area, it has not been possible to measure well on extremely thin superabrasive grain rims. In addition, a superabrasive wheel manufactured according to a certain design is attached to an actual machine for grinding, and the power required at that time (grinding power, W
), and it was possible to judge from the value whether the degree of bonding was as designed, but it was impossible to determine it before use because it had to be ground.

In the case of a so-called full-thickness type wheel where there is no distinction between the rim part and the core part, it is possible to measure the dynamic elastic modulus and use it as the wheel's degree of bonding. As mentioned above, the degree of bonding of a normal superabrasive wheel cannot be directly measured, and has been estimated indirectly from the design details.

For this reason, when manufacturing and using conventional superabrasive wheels, it is difficult to judge whether the wheel, which is a product, has been manufactured correctly as designed, and whether the actual user will be able to achieve the desired grinding effect. The problem was that it was impossible to judge.

In the case of this superabrasive wheel, three types of bonding agents have been put into practical use: resinoid bond, metal bond, and vitrified bond, but among these, wheels made of vitrified bond can be used immediately after manufacture, and are easier to use than others. Produced more than bonded super abrasive wheels,
It is used. Therefore, it has been desired to develop a measuring method that can accurately evaluate the degree of bonding of a vitrified superabrasive wheel before use.

[Object and structure of the invention]

Therefore, in view of the above-mentioned current situation, the present invention aims to examine the degree of bonding of the vitrified superabrasive wheel so that it can be correctly determined whether it has been manufactured correctly as designed and whether it can exhibit the expected grinding effect. The aim is to develop a method that can be measured before use.

As a result of extensive experiments to achieve this objective, the present inventors measured the cross-sectional unevenness waveform of the outer periphery of the vitrified superabrasive wheel, and based on certain criteria from among the peaks obtained, the superabrasive When calculating the peaks and further calculating the distribution of the number of peaks due to superabrasive grains at regular intervals of depth from the surface, find the depth from the surface and the wheel where the number is maximum, that is, the maximum number of cutting edges. We have found that there is a certain relationship between the degrees of bonding, and therefore, for wheels with various degrees of bonding for which the degree of bonding is known, we have determined in advance the relationship between the depth from the surface that yields the maximum number of cutting edges and the degree of bonding. To represent this in a graph, measure the unevenness waveform of the surface used for grinding as described above for this type of wheel with an unknown degree of bonding, find the depth from the surface at which the maximum number of cutting edges occurs, and calculate it in the graph above. The inventors have discovered that the degree of bonding of the wheel can be accurately and easily measured before use, that is, non-destructively, by applying the method to the present invention.

Therefore, the present invention measures the uneven waveform of the outer surface of a vitrified superabrasive wheel, determines the number of peaks caused by the superabrasive grains at each fixed depth, and determines the degree of bonding of the wheel from the depth showing the maximum number of peaks. The present invention provides a method for measuring the degree of bonding of a vitrified superabrasive wheel, which is characterized by determining the degree of bonding of a vitrified superabrasive wheel.

[Detailed description of the invention]

The present invention will be explained in detail below.

First, the cross-sectional unevenness waveform of the outer periphery of the vitrified superabrasive wheel is measured. As mentioned above, superabrasive wheels have a thin layer of superabrasive grains adhered to the outer circumferential surface of the wheel, and that outer circumferential surface is used for grinding, and a displacement meter is run over the entire circumference of the outer circumferential surface used. Measure the unevenness of the surface and obtain a waveform that shows the change. In the case of a vitrified bond superabrasive wheel, unlike metal bond or resinoid bond wheels, pores exist in the surface layer and fine irregularities are formed on the surface, so that waveforms can be obtained.

In addition, when performing this measurement, the outer periphery surface to be used should be well finished in advance using a finishing machine. After attaching this whetstone to the grinding machine, use a diamond tool to smooth the whetstone so that it becomes a perfect circle. This is generally called truing. Therefore, the 811 determination should be performed after finishing the grinding surface of the grindstone or after truing.

The super abrasive wheel, which is set in the finishing machine or set on a special measuring stand, is measured using a drive roll.
The unevenness on the outer circumferential surface is measured by a displacement meter while rotating by 60 inches.The displacement meter may be a contact type having a diamond tip, or a non-contact type using a laser.

The drive speed for rotating this wheel is preferably 3 mm/sec or less when using a contact displacement meter, and is 10+n
/second or more is not preferable because jumping may occur. On the other hand, in the case of a non-contact type displacement meter, the grinding wheel is 1 to 20 μl/
It can be widely applied in seconds. In the case of a wheel with a large diameter, the outer periphery is divided into an appropriate number of parts, for example, into 4 parts and each part is measured by 90'', and the calculation is performed by combining the parts into one round.

In this way, a constant sampling time, e.g. Δ-1
If sampling is performed every 0 milliseconds, a waveform as shown in FIG. 1, for example, can be obtained. Many peaks are formed when this waveform rises and then falls. There are two peaks, one due to the superabrasive and the other due to the vitrified bond, but it is important to extract only the peak due to the superabrasive. In the present invention, we focus on the size of the superabrasive grains and vitrified bond in the wheel surface layer, and the differences in the surface shape patterns after each finishing or truing, and determine the criteria for extracting the peak due to the superabrasive grains. Judgment was based on that.

In the case of the present invention, a peak after three consecutive points where the sampling output is higher than the previous level is determined to be a peak due to superabrasive grains.For example, peak A in Fig. 1 is higher than the previous level for three consecutive points. Since it is large, it is judged that the peak is caused by super abrasive grains. This criterion may change depending on the wheel specifications, especially the grain size. In this figure, δ indicates the reference depth. In this way, the peak due to the superabrasive grains is determined from the cross-sectional waveform of the surface used for grinding, and from this, the two-dimensional and three-dimensional distribution of the superabrasive grains, which is useful in practice, is determined. The degree of coupling of the wheel is then measured.

Planar distribution is within a certain depth from the surface (e.g. 2 μm)
is the average interval between peaks due to the superabrasive grains present in
Number of peaks (N) due to superabrasive grains existing at that depth
The distance (μ) is obtained from the actual measurement L-■ as follows, and this distance is generally called the cutting edge distance.

μmL/N Figure 2 shows the cutting edge spacing (μ).

Also, as a three-dimensional distribution, the number of peaks due to superabrasive grains based on the above-mentioned criteria is determined from the surface at a certain depth, for example, every 2 μm, and from the frequency distribution, the number of peaks is the maximum, that is, the maximum cutting edge. Determine the depth Dl from the surface, which is a number. Figure ff13 explains how to find the depth (Dl) that gives the maximum number of cutting edges (P■aX).

According to the present invention, the distance between the cutting blades determined as described above and the depth from the surface at which the maximum number of cutting blades is obtained are approximately linear as shown in Fig. 4.5. It was found that there is a relationship between That is, the degree of coupling F, HSJ
, L wheel cutting edge spacing (μ) and depth of maximum number of cutting edges (
It has been found that pl) decreases as the degree of bonding increases from F to L, that is, as the bond gradually becomes harder, and that there is a regular relationship between them and the degree of bonding.

Therefore, if we use this to obtain graphs like the one shown in Figure 4.5 for wheels with various degrees of connectivity for which the degrees of connectivity are known,
By determining the cutting edge spacing and the depth from the surface that yields the maximum number of cutting edges for a wheel with unknown bonding degree, it is possible to non-destructively know the bonding degree before use for grinding.

As is well known in the industry, the degree of bonding of grinding wheels is determined alphabetically from the softest to the ES according to the Japanese Industrial Standards.
It is represented by the symbols F, G, . . . , and a grinding wheel made of super abrasive grains has a degree of bonding that is harder than usual. The wheel specifications are displayed using symbols such as abrasive grain type, grain size, degree of bonding, structure, bond type, etc.

In the present invention, a three-dimensional distribution is particularly determined rather than a planar distribution, and the degree of bonding is determined from the depth from the surface where the maximum number of cutting edges is obtained.

Table 1 shows the details of the specifications of the wheels used to obtain this graph, Table 2 shows the grinding conditions, and Table 3 shows the finishing conditions of the surfaces used. As mentioned above, this was measured for a wheel whose degree of bonding was confirmed to be in accordance with the design specifications from the grinding power, and this graph is usually created according to the specifications of the wheel, especially the grain size. .

Table 1 Table 2 Table 3 Example Three vitrified superabrasive wheels with different degrees of bonding were made using hexagonal boron nitride called Borazon.

Its dimensions (ms) and design specifications were as follows.

I, 11. x 10x 8 B170F200V
C2o, 20x15X6 B170J20
0VC2ha, 25X10X12.5 8170+1
200VC2 These wheels were finished under the following conditions.

Wheel circumferential speed: 2.970 m/min Tool wheel circumferential speed: 1.800 m/min Depth of cut: 5 μ Transverse feed speed: 50 μ/ray After finishing in this way, use a diamond measuring terminal and a displacement meter with a tip radius of 5 μR at a speed of 2 dragons/sec. The waveform of the cutting surface of each of the above wheels was measured by driving with The diameter of the opening and the diameter of the hole were 30.0 μm, 11165 μm, and 19.0 μm, respectively.

When this is applied to the graph created under the above conditions (Figure 5), the degree of connectivity F, as shown in Figure 6, is
It became clear that they had JSH, that is, that they were all made according to the design specifications.

〔Effect of the invention〕

According to the present invention, it is possible to accurately determine whether the vitrified bond superabrasive wheel is made to have the degree of bonding specified by the design specifications and whether it will exhibit the expected grinding effect before using it for grinding without causing damage. can.

[Brief explanation of drawings]

Figure 1 is a diagram showing a waveform of irregularities on the outer periphery of a wheel to explain the criteria for determining peaks due to superabrasive grains according to the present invention, and Figure 2 is a similar diagram to explain the depth direction distribution of the number of superabrasive grain peaks. Figure 3 is an explanatory diagram for explaining the means for determining the depth from the surface that yields the maximum number of cutting edges, Figure 4 is a graph showing the relationship between cutting edge spacing and degree of wheel coupling, and Figure 5. 6 is a graph showing the relationship between the depth from the surface that gives the maximum number of cutting edges obtained by the present invention and the degree of wheel bonding, and FIG. 6 is a graph for explaining the method for measuring the degree of wheel bonding according to the embodiment of the present invention. It is a graph.

Claims (1)

[Claims] After finishing the outer circumferential surface of the vitrified superabrasive wheel, measure the cross-sectional unevenness waveform of the outer circumferential surface, calculate the number of peaks caused by the superabrasive grains at each fixed depth, and start from the depth showing the maximum number of peaks. A method for measuring the degree of bonding of a vitrified superabrasive wheel, characterized by determining the degree of bonding.