JP2831425B2 - Method for measuring the degree of bonding of vitrified superabrasive wheels - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel method for measuring the degree of bonding of a vitrified superabrasive wheel.

[Conventional technology and its problems]

Conventionally, the degree of bonding is important in various wheels used for grinding metal materials, and it is required that the wheels have a sufficient degree of bonding so that the expected grinding effect can be exhibited without the abrasive grains falling off during operation. Unlike the general whetstone using alumina or silicon carbide, which is used as an alundum or carborundum for each product, hard and expensive so-called superabrasives made of natural or synthetic diamond or hexagonal boron nitride (CBN) are used. In the case of a superabrasive wheel that is bonded with a binder such as vitrified bond, it is necessary to have a particularly suitable bonding degree so that expensive superabrasive particles that are hard and can be used for a long time are not dropped off early. Is done.

Conventionally, the Ogoshi type bond tester has been widely used for measuring the bond of a general whetstone. This is to measure the depth (unit: mm) of the bit engraving by rotating a bifurcated bit by 120 ° on the surface where the sample is used. Take the average. The degree of coupling of a general grindstone is evaluated by using the outer Rockwell hardness (Hr) or a dynamic elastic modulus measurement method using a sonic comparator or ultrasonic waves.

On the other hand, in the case of the super-abrasive wheel as described above, there is no suitable measuring method for directly measuring the degree of bonding. In general, superabrasive wheels are expensive, so the superabrasives are usually only thinly bonded to the outer peripheral surface of the wheel used for grinding to a thickness of about 1 to 3 mm together with a binder. The part or core part is made of another material, for example, metal. For such thin and expensive superabrasive rims, the Ogoshi type measuring machine that uses a bit to measure the indentation depth as described above cannot be used, and for extremely thin superabrasives Even if a hardness measuring tool is used, it is damaged and the hardness cannot be measured. Even if measured, reliable data cannot be obtained. Also, the measurement method using ultrasonic waves requires a certain thickness or area, so that it was not possible to measure well with a very thin superabrasive rim. In addition, the power required for attaching and grinding a superabrasive wheel manufactured under a certain design to an actual machine (grinding power / W)
Was measured and it was possible to judge whether or not the degree of bonding was as designed, but it was necessary to grind and use it before use.

In the case of a so-called metal type wheel where there is no distinction between the rim and the core, it is possible to measure the dynamic elastic modulus and use it as it is as the degree of coupling of the wheel. The degree of bonding of the superabrasive wheel cannot be directly measured as described above, and a method of indirectly estimating from the design contents has been adopted.

For this reason, in the production and use of conventional superabrasive wheels, it is not possible to judge whether the product wheel is manufactured correctly as designed and whether the actual user can exhibit the expected grinding effect. There was a problem that it could not be determined.

In the case of this superabrasive wheel, three types of binders, resinoid bond, metal bond, and vitrified bond, have been put into practical use. Among them, wheels made of vitrified bond can be used immediately after production and are easy to use. Are manufactured and used more than super-abrasive wheels by Bond. Therefore, it has been desired to develop a measuring method capable of correctly evaluating the bonding degree of the vitrified superabrasive wheel before use.

[Object and structure of the invention]

Accordingly, the present invention, in view of the current situation as described above, the degree of bonding so that it can be correctly determined whether the vitrified super-abrasive wheel is manufactured correctly as designed, and whether the expected grinding effect can be exhibited. The aim is to develop a method that can be measured before use.

The inventors of the present invention have conducted intensive experiments to achieve such an object, and have measured the cross-sectional irregularity waveform of the outer peripheral use surface of the vitrified super-abrasive wheel. When determining the peak, and further determining the distribution of the number of peaks due to the superabrasive grains at regular intervals of the depth from the surface, the number of peaks is the maximum, that is, the depth from the surface and the wheel with the maximum number of cutting edges It has been found that there is a certain relationship between the degree of coupling and the degree of coupling between the depth from the surface and the degree of coupling, which is the maximum number of cutting edges, in advance for wheels of various degrees of coupling with known degrees of coupling. If expressed in a graph, for this kind of wheel with an unknown degree of coupling, the unevenness waveform of the grinding use surface is measured as described above, and the depth from the surface at which the maximum number of cutting edges is obtained therefrom is obtained. To apply to In other words in a non-destructive before use What is had completed the present invention have found that it is possible to correctly easily measure the degree of binding its wheels.

Therefore, the present invention measures the uneven waveform of the outer peripheral use surface of the vitrified superabrasive wheel, determines the number of peaks due to the superabrasive grains at every constant depth, the degree of coupling of the wheel from the depth showing the maximum peak number And a method for measuring the degree of bonding of a vitrified superabrasive wheel.

[Specific description of the invention]

 Hereinafter, the present invention will be described in detail.

First, the cross-sectional unevenness waveform of the outer peripheral use surface of the vitrified superabrasive wheel is measured. As described above, in the superabrasive wheel, superabrasives are thinly adhered to the outer peripheral surface of the wheel in a layered manner, and the outer peripheral surface is used for grinding, and a displacement meter is run over the entire outer peripheral use surface to execute the grinding. The irregularities on the surface are measured, and a waveform showing the change is obtained. In the case of a vitrified bond superabrasive wheel, unlike the case of metal bond or resinoid bond, pores exist in the surface layer and fine irregularities are formed on the surface, so that a waveform can be obtained.

In this measurement, the outer peripheral use surface is well finished in advance with a finishing machine. After attaching the grinding stone to the grinding machine, the grinding stone is deflated with a diamond tool so that it becomes a perfect circle. This is commonly referred to as truing.
Therefore, the measurement is to be performed after finishing the grinding surface of the grindstone and after truing.

Using a drive roll, the superabrasive wheel set on the finishing machine or set on a dedicated measuring table
Measure the irregularities on the outer peripheral surface with a displacement meter while rotating 360 °. The displacement meter may be a contact type having a diamond tip terminal or a non-contact type using a laser.
The drive speed for rotating this wheel is desirably 3 mm / sec or less when a contact displacement meter is used, and is undesired if it is 10 mm / sec or more because jumping or the like occurs. On the other hand, in the case of a non-contact type displacement meter, the whetstone can be applied to a wide range of 1 to 20 mm / sec. In the case of a wheel having a large diameter, the outer circumference is divided into an appropriate number, for example, divided into four parts and measured at 90 °.

Thus, a constant sampling time, for example, Δ =
By sampling every 10 milliseconds, for example, a waveform as shown in FIG. 1 is obtained. Many peaks are formed when this waveform rises and then falls. There are peaks due to superabrasive grains and peaks due to vitrified bonds. It is important to extract peaks of only superabrasive grains. In the present invention, the size of the super-abrasive grains and the size of the vitrified bond in the wheel surface layer, and a determination criterion for extracting peaks due to the super-abrasive grains by focusing on the difference in the pattern of the surface shape after each finishing or truing, Judged accordingly.
In the case of the present invention, the peak after three consecutive points where the sampling output is higher than the immediately preceding level is determined to be the peak due to the superabrasive grains. For example, the peak A in FIG. Since it is large, it is determined that the peak is caused by superabrasive grains. This criterion may change depending on the wheel specifications, particularly the granularity. In this figure, δ indicates the reference depth In the present invention, the peak due to the superabrasives is obtained from the cross-sectional waveform before grinding in this way, and the planar and three-dimensional distribution of the superabrasives that are practically useful from this are obtained. Then, the degree of connection of the wheel is measured. The planar distribution is an average interval between peaks caused by superabrasive grains within a certain depth (for example, 2 μm) from the surface, and the number of peaks (N) caused by the superabrasive grains existing at the depth is substantially measured. The distance (μ) is obtained from the length Lmm as follows, and this distance is generally called a cutting edge distance.

 μ = L / N FIG. 2 shows the cutting edge interval (μ).

The number of peaks due to superabrasive grains based on the above criterion is determined as the three-dimensional distribution at every fixed depth from the surface, for example, at every 2 μm, and the number of peaks becomes maximum from the frequency distribution, that is, the maximum cutting edge determining the depth D ₁ of the from the surface to be few. Figure 3 is a depth which becomes most important number of blades (Pmax) (D ₁₎
It explains how to ask for.

According to the present invention, the distance between the cutting edges determined as described above and the depth from the surface at which the maximum number of cutting edges is reached is substantially linear between the degree of coupling of the respective wheels as shown in FIGS. It was found that there was a relationship of That is, the coupling degrees F, H,
The distance between the cutting edges (μ) and the depth of the maximum number of cutting edges (D ₁ ) of the wheels J and L become smaller from the degree of coupling F toward L, that is, gradually become harder, and become constant between them and the degree of coupling. It has been found that there is a regular relationship.
Therefore, if graphs such as those shown in FIGS. 4 and 5 are obtained for wheels of various coupling degrees with known coupling degrees using this,
By obtaining the cutting edge interval and the depth from the surface where the maximum number of cutting edges is obtained for a wheel whose coupling degree is unknown, it is possible to know the degree of coupling nondestructively before using grinding.

As is well known in the art, the degree of bonding of a grindstone is represented in alphabetical order by symbols E, F, G,... In accordance with Japanese Industrial Standards. have. In the wheel specifications, the type of abrasive grains, the grain size, the degree of bonding, the structure, the type of bond, and the like are indicated by symbols.

In the present invention, in particular, a three-dimensional distribution is obtained rather than a two-dimensional distribution, and the degree of connection is obtained from the depth from the surface at which the maximum number of cutting edges is obtained.

Table 1 shows the specifications of the wheels used in obtaining this graph, Table 2 shows the grinding conditions, and Table 3 shows the finishing conditions of the used surface. It should be noted that, as described above, the degree of coupling was measured for a wheel for which the degree of coupling was confirmed to be in accordance with the design specifications from the grinding power, and this graph is usually created according to the wheel specifications, particularly the grain size. .

EXAMPLES Three vitrified superabrasive wheels with different degrees of bonding were made using hexagonal boron nitride called borazon. The dimensions (mm) and design specifications were as follows.

B.16 × 10 × 6 B170F200VC2 B.20 × 15 × 6 B170J200VC2 C.25 × 10 × 12.5 B170H200VC2 These wheels were finished under the following conditions.

Wheel peripheral speed 2.970m / min Tool wheel peripheral speed 1.800m / min Depth of cut 5μ Lateral feed speed 50μ / rev After finishing in this way, drive a diamond measuring terminal and a displacement meter with a tip radius of 5μR at a speed of 2mm / sec. When the waveform of the cutting surface of each wheel was measured, the number of peaks due to the superabrasive grains was measured at every 2 μm depth, and the depth from the surface at which the maximum number of cutting edges was obtained was obtained. Are each
They were 30.0 μm, 11.5 μm and 19.0 μm. When this is applied to a graph (FIG. 5) created under the above-described conditions, as shown in FIG. 6, the graphs have coupling degrees F, J, and H, respectively. It became clear.

〔The invention's effect〕

According to the present invention, whether the vitrified bond superabrasive wheel is made to have the degree of bonding of the design specifications,
Before using the grinding, check whether the grinding effect is as expected.
You can know correctly without destroying.

[Brief description of the drawings]

FIG. 1 is a diagram showing a wheel outer peripheral irregularity waveform for explaining a criterion for judging a peak due to superabrasive grains according to the present invention, and FIG. 2 is a view for explaining a depth direction distribution of the number of superabrasive grain peaks. FIG. 3 is an explanatory diagram for explaining means for obtaining a depth from the surface at which the number of cutting edges is the maximum, FIG. 4 is a graph showing the relationship between the cutting edge interval and the wheel coupling, FIG.
FIG. 6 is a graph showing the relationship between the depth from the surface at which the maximum number of cutting edges is obtained according to the present invention and the degree of wheel coupling, and FIG. 6 is a diagram for explaining a method of measuring the degree of coupling of the wheel according to the embodiment of the present invention. It is a graph of.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) G01N 3/40 G01N 13/00 G01N 33/40 G01N 15/02 B24D 3/00-18/00

Claims (1)

(57) [Claims] After finishing an outer peripheral surface of a vitrified superabrasive wheel, a cross-sectional unevenness waveform of the outer peripheral surface is measured, and the number of peaks due to the superabrasive particles is determined for each predetermined depth to indicate the maximum peak number. A method for measuring the degree of bonding of a vitrified superabrasive wheel, wherein the degree of bonding of the wheel is obtained from the above.