JP3006933B2 - Super abrasive grinding wheel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding wheel mounted on a machine tool and rotating or linearly moving to grind a workpiece, and more specifically, a superabrasive is bonded to a predetermined surface of a base with a binder. The present invention relates to a superabrasive grinding wheel formed with a formed grinding layer.

[0002]

2. Description of the Related Art Grinding fine ceramics often used in automobile parts such as automobile engines and turbochargers, machine parts such as spindles of machine tools, housings, IC boards, cutting tools and various electronic parts. As the grinding wheel, a super-abrasive grinding wheel using diamond or CBN abrasive grains as abrasive grains is often used.

[0003] This superabrasive grinding wheel is manufactured by forming an abrasive layer made of a superabrasive and a binder on a predetermined surface of a base, in addition to fixing the abrasive by a so-called electrodeposition method. I have. That is, after incorporating the base into a mold or a carbon mold, the superabrasive grains and the binder mixed at a predetermined mixing ratio are filled with a binder, and then sintered or reacted and hardened depending on the type of the binder to form a grindstone layer. Then, it is manufactured by further performing various machining processes as needed.

[0004] The binder includes copper, cobalt, silver, iron,
Metals such as nickel, tin, zinc, tungsten or alloys thereof, phenol, polyamide, bakelite,
Resins such as polyurethane and epoxy, or vitrified, etc. are used, but in order to further enhance the wear resistance and lubricity of the grindstone layer, various fine particles are usually added as a reinforcing material or a filler in an arbitrary amount. It is.

Conventionally, as the above-mentioned fine particles, hard fine particles such as aluminum oxide, silicon oxide, iron oxide, tungsten carbide, silicon carbide, titanium carbide, boron carbide and chromium carbide, or boron nitride, sericite, graphite fluoride, Lubricating fine particles such as graphite, molybdenum disulfide, tungsten disulfide, tantalum disulfide, fluororesin, tungsten diselenide, and molybdenum diselene are used.

Further, when a resin is used as the binder, metallic fine particles composed of fine powders of copper or copper alloy, silver, iron, cast iron, nickel, cobalt, tungsten, tungsten carbide, metal oxide and the like are used. Have been.

[0007]

In the case of a superabrasive grinding wheel, the performance and properties of the wheel are determined by the material of the fine particles described above,
It depends considerably on the size and the amount of addition. However, conventionally, the material, addition ratio, and the like of hard fine particles, lubricating fine particles, or metallic fine particles are selected according to the purpose of use of the grindstone and the main component of the binder used, and the work is complicated.

Moreover, when the hard fine particles are added, the binder, and hence the wear resistance of the grindstone layer, is improved, but the frictional resistance is increased. In many cases, cutting chips adhere to the unevenness on the surface of the layer to cause clogging. Further, since the particle shape and the classification are slightly different for each production lot, the grinding performance may be slightly changed for each grinding wheel.

The above-mentioned lubricating fine particles can improve lubricity and reduce frictional resistance by being added thereto. However, in the case of super-abrasive particles having a fine particle size, the holding power is reduced and the super-abrasive particles are reduced. Are easy to fall off, and the wear resistance is low, so that the life of the grindstone is shortened.

Further, the metallic fine particles have the same problems as the hard fine particles described above, and the metallic fine particles exposed on the binder come into contact with the grinding dust to form a thin film on the surface of the binder. However, there is a problem that a clogging state is easily caused.

On the other hand, in recent years, the number of revolutions of the grindstone at the time of machining has been increased, and the grinding heat generated at the time of grinding causes a considerably high temperature at the grinding action point. May be 500 ° C. or higher. For this reason, there is a risk that the binder will be thermally degraded due to the grinding heat or burns and chipping will occur on the processed surface of the workpiece. To prevent this, a grindstone with high lubricity, wear resistance and high bonding The development of layers is desired.

However, the above-mentioned conventional fine particles have a particle size of several microns even at the smallest, so that when the particle size of the superabrasive particles becomes small, the material and amount of the fine particles that can be added are extremely limited, and satisfactory grinding wheel performance is obtained. Is difficult to achieve.

For example, in a diamond wheel having a particle size of # 2000 to 6000 used for grinding a general ferrite composite material, grinding is performed by mixing a metal powder and a ceramic fine powder selected based on experience into a binder. Although efforts are being made to diffuse heat and improve the abrasion resistance of the binder, the actual effect has not been obtained.

The present invention has been made in view of the above-mentioned circumstances, and has as its object the purpose of having a simple structure, extremely rich lubrication and wear resistance, and a high degree of bonding of superabrasive grains. It is another object of the present invention to provide a superabrasive grinding wheel capable of suppressing generation of grinding heat, preventing the binder from deteriorating, and improving the life of the grinding wheel.

[0015]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a superabrasive grain comprising a grindstone layer formed by bonding a superabrasive grain to a predetermined surface of a base with a binder. In the grinding wheel, ultrafine diamond particles having a rounded shape having an average particle diameter of 100 angstrom or less (hereinafter, referred to as ultrafine particles) or graphite is chemically coated on at least a part of the surface of the ultrafine particles in the binder. This is because the coated ultrafine particles coexist.

The ultrafine particles used in the present invention are very fine particles having an average particle diameter of 100 angstrom or less and have a rounded shape, unlike the existing diamond fine particles, and therefore have no abrasive mechanism.
Does not scratch or wear the ground surface. In addition, since the ultrafine particles are diamond, they are very hard, have a Knoop hardness of Hk9000 or more, have little particle destruction, and have a low friction coefficient of about 1/10 or less that of carbide tools, etc., and are extremely lubricating themselves. Rich in sex.

For example, a coating formed by mixing the ultrafine particles with a liquid resin and spraying the mixture on a paper using a spray gun, or a block obtained by adding 10% by volume to a phenol resin and stirring and mixing to react and harden. Even when rubbed with a soft plastic lens, the surface of the plastic lens is not scratched at all and has very good sliding. According to experiments, it has been confirmed that these ultrafine particles have the same or higher superlubricity as Teflon powder.

Therefore, the grindstone layer obtained by sintering or react-hardening the binder in which the ultrafine particles coexist with the superabrasive grains has both excellent lubricity and abrasion and friction resistance.
In this case, when all or a part of the ultrafine particles to be used are ultrafine particles in which graphite is chemically coated on the outside of the nucleus of the ultrafine particles and coexist in a binder, the lubricity is further improved.

Generally, ultrafine diamond particles are produced by detonating a TNT powder in a pressure vessel filled with an inert gas and applying ultrahigh pressure and ultrahigh temperature to graphite.
Ultrafine diamond particles having a rounded shape with a particle diameter of 100 Å or less as used in the present invention can be obtained by controlling the particle growth rate to a large value of, for example, 5 mm / S.

The ultrafine particles whose surfaces are chemically coated with graphite have a particle diameter of 100%.
It can be obtained by mixing ultrafine diamond particles having a rounded shape of angstrom or less with TNT powder and RDX powder and exploding them in a pressure vessel without using an inert gas.

As the binder to which the ultrafine particles are added, a substance known as a binder for a superabrasive grinding wheel can be used. For example, copper, tin, zinc, tungsten, silver, iron,
Cast iron, nickel, cobalt, and their respective alloys, or resins such as phenol, polyamide, polyurethane, silicon carbide, alumina, graphite, boron nitride,
One or more of metal powders or resin powders such as iron sulfide, molybdenum disulfide, Teflon, and hexane can be used. At this time, these powders preferably use fine powders of several μm to several tens of μm.

The ultrafine particles preferably coexist in an amount of preferably 1 to 40%, particularly preferably 3 to 20%, based on the total amount of the binder. Even if the content of the ultrafine particles is low, the ultrafine particles have an average particle size of 100 angstrom or less and the number of particles contained is close to infinity, so that sufficient lubricity and wear resistance can be obtained.

The method of manufacturing a superabrasive grinding wheel of the present invention can be the same as the conventional method of manufacturing a superabrasive grinding wheel, except that ultrafine particles are added to a binder. That is, for example, first, superabrasive grains are added to a binder to which ultrafine particles have been added together with a suitable volatile wetting agent, and the mixture is sufficiently mixed by a stirring and mixing device, and then the volatile wetting agent is evaporated to perform a granulation treatment.

Then, a base is incorporated into a mold or a carbon mold, and a mixture of the binder and the abrasive grains containing the ultrafine particles is filled, and cold forming is performed. Then, vacuum, hydrogen, ammonia gas, inert gas, It is manufactured by sintering in an atmosphere of gas or the like or, if necessary, by reaction hardening when the binder is mainly composed of resin. Various other machining is performed as necessary.

[0025]

【Example】

Diamond abrasive grains (particle diameter: 2 to 4 μm, concentration 150) Ultra fine particles 3% by volume Polyamide resin powder Residue After assembling the base into the mold, a binder powder containing abrasive grains and ultra fine particles mixed at the above volume ratio (polyamide) Resin powder) and cold molding at 600 kg / cm ² , sintering under vacuum at 230 ° C. for 60 minutes, and after cooling, disassemble the mold and perform machining. A superabrasive grinding wheel was manufactured.

FIG. 1 shows a cross section of a grindstone layer of the superabrasive grinding wheel of the above embodiment.
The diamond abrasive grains 3 are dispersed, and a part of the abrasive grains 3 is fixed while protruding from the surface of the binder 2. In addition,
FIG. 2 shows a cross section of a grindstone layer of a conventional superabrasive grindstone, in which diamond abrasive grains 6 are dispersed in a binder 5 containing fine particles 4, and 7 is a portion where the diamond abrasive grains 6 have fallen off. Show.

Comparison of the performance and the like with the conventional product shown in FIG. 2 manufactured in the same manner as in the embodiment except that a metal powder having an average particle diameter of 10 μm was used instead of the superabrasive grinding wheel and the ultrafine particles in the above embodiment. Therefore, when the composite material of ferrite and glass was actually ground, in the case of the grinding wheel of the example, the occurrence of chipping after the grinding of both the ferrite and the glass was significantly reduced, and especially, the ferrite-processed surface was hardened during grinding. It was confirmed that grinding heat due to friction was reduced, and cracking and chipping were significantly improved as compared with the conventional product.

Further, the grinding heat at the grinding action point was at least 350 ° C. or more in the conventional product, whereas the grinding wheel of the example generated heat of 200 to 250 ° C. Furthermore, the adhesion of the grinding debris on the grinding action surface of the used grinding wheel is extremely small in the grinding wheel of the embodiment as compared with the conventional product, and in the conventional product, the binder is decomposed by heat and the deterioration is deteriorated. Compared with the example, little change was observed in the binder in the examples.

The deterioration of the binder can be determined by estimating the amount of the dropped abrasive grains based on the amount of the grinding streaks on the ground surface. In the case of the grinding wheel of the embodiment,
The amount of generation of grinding streaks is one-tenth or less of the conventional product, and the life of the grindstone is at least 2-2.5 times longer than that of the conventional product.

[0030]

As described above, according to the present invention, in a superabrasive grinding wheel provided with a grindstone layer in which superabrasive grains are bound by a binder, the binder has an average particle size of 10%.
The coexistence of ultrafine diamond particles with a rounded shape of 0 angstrom or less enables the binder to have excellent lubricity, abrasion resistance and abrasion resistance, suppress the generation of grinding heat, and reduce the deterioration of the binder. Can be prevented. As a result, it is possible to provide a superabrasive grinding wheel capable of improving the performance and life of the grindstone and improving the processing accuracy and quality of the workpiece.

[Brief description of the drawings]

FIG. 1 is a longitudinal side view of a grinding wheel layer of a superabrasive grinding wheel according to an embodiment of the present invention.

FIG. 2 is a longitudinal side view of a grindstone layer of a conventional superabrasive grinding wheel.

[Explanation of symbols]

 1 ... ultra fine particles, 2 ... binder, 3 ... abrasive grains.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B24D 3/34 B24D 3/00 320 B24D 3/00 330 B24D 3/02 310

Claims (3)

(57) [Claims] 1. A superabrasive grinding wheel formed by forming a grindstone layer in which superabrasive grains are bonded to a predetermined surface of a base with a binder, wherein the binder has an average particle diameter of 100 angstrom or less. A superabrasive grinding wheel characterized by coexistence of ultra-fine diamond particles having a tinged shape. 2. A superabrasive grinding wheel according to claim 1, wherein at least a part of said ultrafine diamond particles has a surface chemically coated with graphite. 3. The grindstone layer comprises the ultrafine diamond particles, copper, tin, zinc, tungsten, silver, iron, cast iron, nickel, cobalt, or an alloy thereof, phenol resin, polyamide resin, silicon carbide, alumina, A binder containing one or more powders of graphite, polyurethane, boron nitride, iron sulfide, molybdenum disulfide, teflon, hexamine, and the like, and a superabrasive are formed by sintering or reaction hardening. The superabrasive grinding wheel according to claim 1, wherein