JPH0115501Y2 - - Google Patents

Description

[Detailed description of the invention] Diamond grinding wheels or CBN grinding wheels generally have a structure in which a grinding wheel portion containing diamond or CBN abrasive grains, that is, a diamond layer, is attached to the periphery of a metal base (hereinafter referred to as the base metal). Fig. 1 shows a typical example of a peripheral type grindstone, and Fig. 3 shows a typical example of a cup type grindstone. In the figure, 1 is a base metal, which has a center hole 2 for attachment to the rotating shaft of the machine. 3 is the diamond layer, the normal number
Molded to a thickness of mm.

The diamond layer 3 has a structure in which abrasive grains are scattered in a metallic, resinous, or glassy matrix, and the matrix is also called a bond. For manufacturing, a mixture of bond material powder and abrasive grains is heat-compressed and sintered.

An intermediate layer is often interposed between the base metal and the diamond layer. FIG. 2 is a sectional view showing this structure for a peripheral type and FIG. 4 for a cup type. The intermediate layer 4 is formed of the same or similar material as the bond, but does not contain abrasive grains.

The effectiveness of the middle layer lies in its buffering effect. That is, by absorbing the impact acting on the diamond layer, the grinding performance of the whetstone is improved and destruction of the diamond layer is prevented.
Stresses that cause diamond layer destruction always exist, such as external force due to grinding resistance that sometimes acts shockingly, centrifugal force due to high-speed rotation, and stress due to the difference in thermal expansion between the diamond layer and the base metal. The intermediate layer distributes and relieves these stresses, thereby reducing the likelihood of failure.

Among the three types of bonds mentioned above, the glassy bond is called a vitrified bond. A whetstone using this, that is, a vitrified whetstone, is prized because it exhibits excellent performance depending on the material to be cut and the purpose of grinding, but it has the disadvantage that it is easily broken due to the brittle glass bond.

If a minute crack occurs in the diamond layer or intermediate layer, the various stresses mentioned above will cause the crack to expand and propagate, leading to complete destruction. The breakage occurs during grinding when the whetstone is rotated at high speed, and the centrifugal force causes fragments to scatter and harm the surrounding area. It is extremely dangerous, especially for workers. As mentioned above, the intermediate layer has the effect of preventing breakage, but it is not completely dangerous, and conventional vitrified diamond (or CBN) grinding wheels have left workers feeling uneasy.

In view of this point, the purpose of the present invention is to provide a vitrified grindstone that does not easily cause cracks, and even if cracks do occur, the cracks will not spread and spread, thus ensuring safety without causing breakage or scattering. There is a particular thing.

The gist of the present invention is that a wire mesh 5 is embedded in the intermediate layer 4, as shown in FIGS. 5 and 6. FIG. 5 is a partial sectional view of a peripheral type whetstone, and FIG. 6 is a partial sectional view of a cup type whetstone, and in both cases, the wire mesh has a planar ring shape.

The wire mesh 5 acts as a reinforcing material for the intermediate layer 4 of the glassy sintered body. This reduces the likelihood of cracks occurring and prevents them from expanding and propagating if they do occur. Even if a crack 6 crosses the intermediate layer 4 as shown in FIG. 7, both sides 7 and 8 of the crack are separated by wire mesh 5.
Since they are connected by , they maintain their original positions and never separate. In other words, even if a crack occurs, the grindstone will not be destroyed or scattered.

The optimal material for the wire mesh 5 is an alloy for glass sealing, such as an Fe--Co--Ni alloy commercially available under the name Kovar. This is because this type of alloy has good adhesion to glass and has a coefficient of thermal expansion matching that of glass. However, experiments have shown that nickel or stainless steel wire mesh is also fully useful. A wire mesh woven from wire rods with a diameter of 0.1 to 0.5 mm is suitable; a wire mesh made of thin wire rods is used for small whetstones, and a wire mesh made of thick wire rods is used for large whetstones.

To manufacture the vitrified grindstone of the present invention, the conventional method can be applied as is, except that a slight additional step is required in the forming process. To give an example of the forming method below, place a diamond layer compact or semi-sintered body in a predetermined mold, load half of the predetermined amount of intermediate layer material powder into the intermediate layer position, press it, and then Place a wire mesh with the specified dimensions and shape. Next, the remaining half amount of powder is loaded and pressed. Thereafter, the diamond layer and the intermediate layer are sintered and formed simultaneously by heating and pressurizing them as in the conventional method.

As described above, since the present invention eliminates the risk of breakage and scattering, the applications of vitrified grindstones are greatly expanded. It is manufactured using existing technology and equipment, and the process is simple, so it has great industrial value.

In the above description, one wire mesh is inserted into the center of the thickness of the intermediate layer, but if the intermediate layer is thick, a plurality of wire meshes may be inserted at appropriate intervals.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a peripheral type grindstone, FIG. 2 is a cross-sectional view of a structure having an intermediate layer as described above, FIG. 3 is a perspective view of a cup-type grindstone, and FIG. 4 is a cross-sectional view of a structure having an intermediate layer as described above. 5 and 6 are partial cross-sectional views of the vitrified grindstone according to the present invention, and FIG. 7 is a cross-sectional view showing a state in which cracks have occurred. 1... Base plate, 2... Center hole, 3... Diamond layer,
4... middle layer, 5... wire mesh.

Claims (1)

[Scope of utility model registration request] In a bitrified bond, an intermediate layer made of the same or similar material as the bond is provided between the grinding wheel portion containing diamond abrasive grains or CBN abrasive grains and the base metal, and a wire mesh is embedded in the intermediate layer. Bitrifided whetstone.