JPS5912425B2 - Grinding wheel inspection method - Google Patents

Description

[Detailed description of the invention] The present invention is made by sintering a mixture of abrasive grains and a binder.

The present invention relates to an inspection method for sintered grinding wheels. In addition,
In the present invention, the above-mentioned sintered grinding wheel refers to so-called sintered grinding wheels such as vitrified grinding wheels and silicate grinding wheels described in detail below, as well as abrasive grains of diamond, alumina, silicon carbide, etc., and powders of metals, alloys, etc. “mixed with a binder consisting of
A grindstone obtained by pressurizing and sintering the mixture by a so-called powder metallurgy method is also colored. To give a brief explanation about the above-mentioned fired whetstone, this seed whetstone is made of a binder made of a fine powder mixture of feldspar, fireclay, soluble clay, and a solvent, and abrasive grains such as diamond, alumina, and silicon carbide as needed. Add a small amount of water and glue and mix.
This is compressed into a predetermined wheel shape, dried, etc., and fired. In this case, the binder does not undergo any chemical change with the abrasive grains, and is heated at a predetermined temperature (about 1300°C) for a predetermined 10 hours. When the binder melts and becomes porcelain by firing, it is important to firm and support the abrasive grains with mechanical bonding to prevent the abrasive grains from falling off and wear out, increasing the service life. By shrinking the volume, predetermined pores (cutting voids) are formed and the grinding performance is improved by 15%.

On the other hand, if the firing temperature during firing is too high, depending on the type of abrasive grains used and the purity and properties of the abrasive grains, for example, in the case of alumina abrasive grains, chemical changes occur between the abrasive grains and the binder. wake up,
The surface of the abrasive grains forms a neoplastic inorganic coating, which disables the self-sustaining function of the cutting edge due to the inherent fragmentation of the abrasive grains.

In addition, in the case of silicon carbide abrasive grains, which are the most commonly used abrasive grains, if there are impurities in the abrasive grains, the impurities act as catalysts, etc., and the abrasive grains decompose at a slight firing temperature. However, the whetstone may expand and turn black due to decomposed graphite.

In addition, even if the porcelain of the binder does not flow at the firing temperature, the pores may be deformed, the state of the formed pores and the abrasive grain distribution may change, and the impact strength may decrease. Processing is extremely important in the production of sintered grinding wheels. A similar problem arises with grindstones manufactured using the powder metallurgy method described above, as the manufacturing process involves sintering at high temperatures. .

As a method for inspecting the sintered state of these sintered grinding wheels, destructive testing and the like have conventionally been used, but this is a sampling inspection and cannot inspect the product itself.

The present invention was proposed in view of these points, and it is possible to determine whether the sintered state of the grinding wheel is good or bad by detecting the state of heat conduction in the sintered grinding wheel using laser beam irradiation as a heat source. It is characterized by

To explain the following with reference to the drawings of one embodiment, 1 is a sintered grinding wheel to be inspected, 2 is its central rotating shaft, and 3 is a laser device as a heating source, which emits light generated by a trigger of a xenon tube 31 into a ruby 32 In addition to this, the laser beam 9 that is stimulated and radiated is focused by a lens 33 to locally irradiate one surface of the grindstone 1 in the rotation axis direction.

4 is an excitation power source; 5 is a heat-sensitive detector such as a thermistor disposed at a location corresponding to the location where the laser beam 9 is irradiated to the local area on the other surface of the grinding wheel 1; 6 is an amplifier; and 7 is a heat-sensitive detector. This is a recorder that records the detected temperature of No. 5.

A switch 8 is inserted between the detector 5 and the amplifier 6, and is turned on in synchronization with the excitation of the xenon 31 by a signal from the power source 4.

When the laser beam 9 generated by triggering the xenon 31 and irradiating the ruby crystal 32 is focused by the lens 33 and irradiated onto the minute pole of one surface of the grinding wheel 1, the irradiated portion of the grinding wheel becomes It heats up rapidly and the heat spreads through the surrounding grinding wheel components.

Of course, this propagation state differs depending on the type and composition of the abrasive grains and binder used in the sintered grinding wheel, but even if the composition etc. are the same, it is affected by the sintering state as described above. It is something that receives. That is, a predetermined amount of a predetermined amount of a predetermined type and particle size as abrasive grains and a predetermined amount of a predetermined type and composition as a binder are thoroughly mixed and compressed into a disk shape of a predetermined size and shape. After forming, drying and shaping, firing in a firing kiln or tunnel kiln in which the firing temperature is adjusted and controlled, cooling and subjecting to an acoustic test using a mallet, the product is subjected to the inspection method of the present invention. However, as shown in Figure 2, those fired to a specified state are
At the start of laser beam irradiation (TO), the temperature detected by the detector 5 is T. After a predetermined time (Ts),
The inspection is passed if the detected temperature has risen to approximately Ts or a temperature in the vicinity, and is in the temperature range (Ms) of the standard product, and the degree of porcelainization of the binder is in the specified state. The degree of bonding is high and good, the pores are well-developed without shape distortion, and there is no change in the abrasive grains or their surfaces, so they have good cutting performance. On the other hand, in the case of insufficient firing, the binder is not sufficiently porcelain and the pores are not sufficiently developed, and the detected temperature is detected as a region (ML).
The retention and bonding of the abrasive grains are not sufficient, and the grindstone 1 is brittle and easily chipped, and its cutting performance is naturally inferior to that of the standard one. In addition, in the case of excessive firing, the binder becomes too porcelain, the formed pores change or become distorted, and the abrasive grains or their surfaces are often altered, and the detected temperature is (MH), and as a grindstone 1, it is weak against impact and easily breaks, and its cutting performance is naturally inferior to that of the standard grindstone.

In this way, the present invention locally irradiates the laser beam 9 on one surface of the sintered grinding wheel 1 in the rotational axis direction, and transmits and conducts heat in the axial direction of the grindstone due to the laser beam 9 irradiation. A detector 5 detects the area on the other surface of the grindstone corresponding to the locally irradiated area, and a switch 8 is turned on to activate the amplifier 6 in synchronization with the irradiation of the laser beam. By detecting and recording this amplified detection signal (temperature) with the recorder 7 from the start of irradiation with the laser beam 9, the temperature after a predetermined time from the irradiation of the laser beam 9 is detected, and this is determined according to the standard. By comparing it with the actual one, it is possible to easily determine whether the sintered state inside the grindstone of the laser beam irradiation section is good or bad.

During this inspection, the grinding wheel 1 is sequentially rotated around the rotating shaft 2 to sequentially change the local irradiation position of the laser beam 9, thereby making it possible to inspect each part of the grinding wheel, and therefore the sintered state of the grinding wheel as a whole. It is possible to easily inspect local variations in the degree of sintering, variations between multiple grinding wheels, etc.

As described above, the present invention allows non-destructive inspection of each part of the grinding wheel, and thus the sintered state of the grinding wheel as a whole, and is extremely effective in terms of quality control of sintered grinding wheels.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the method of the present invention, and FIG. 2 is an explanatory diagram of the inspection of the present invention.

Claims (1)

[Claims] 1. A laser beam is locally irradiated on one surface of the sintered grinding wheel in the rotational axis direction, and the transmitted and conducted heat in the axial direction of the grinding wheel due to the laser beam irradiation is transferred to the other surface of the sintered grinding wheel. The temperature is detected at a location corresponding to the locally irradiated location, and the temperature is measured after a predetermined time from the start of the laser beam irradiation, and the measured temperature is set as the standard temperature of the standard grindstone. An inspection method for a sintered grinding wheel, characterized by determining the sintered state by comparing it with the sintered grinding wheel.