JPH08257917A - Base for grinding wheel, super abrasive grinding wheel and manufacture therefor - Google Patents

Abstract

PURPOSE: To manufacture an Al sintered alloy base with low coefficient of thermal expansion and high Young's modulus by an ordinary sintering method, by using Al as a main part and sintering Si or alloy powder formed by adding more than any one of Fe, Cu, Mg and the like to Si onto the Al. CONSTITUTION: This grinding wheel is a super adrasive rotating grinding wheel of not less than 200mm in diameter, and a base 2 optimum to a large grinding wheel such as a cam grinding wheel whose grinding is carried out at a peripheral speed of more than 60m/s employs an Al as a main part and is manufactured by sintering Si or alloy powder formed by adding more than any one of Fe, Cu, Mg, Mn, Zn, Ni and Cr to Si onto the Al. In this manufacture, after alloy powder is filled into a base-shaped mold at least, it is heated to a temperature within eutectic point temperature ±80 deg.C to be sintered. By fixing a vitrified abrasive grain layer 3 onto the outer peripheral end of the base, the super abrasive grinding wheel is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding wheel for grinding various materials and parts, particularly a grinding wheel for a cam, which is used at a high speed, and a base metal for the grinding wheel.

[0002]

2. Description of the Related Art Generally, as the seed grindstone, a vitrified grindstone or a metal bond grindstone that uses vitrified or metal as a binder for superabrasive grains and has a strong gripping force of the grindstone and a high bond strength is used. . The base metal of these grindstones is made of steel having high strength.

[0003]

[Problems to be Solved by the Invention]
In addition to the above advantages, it is heavy and easily rusted. In particular, a large grindstone such as a cam grindstone has poor workability due to its weight, and a rigid grinder for high speed rotation is required. Further, during grinding, the radius of the base metal is displaced due to the rotation and temperature rise of the grindstone, and there remains a problem that the machining accuracy is reduced.

[0004]

The present invention has been made in order to solve the above problems, and the first feature is that Al is mainly used as a base metal for a grindstone. This is to use an alloy powder obtained by adding 35% by weight or more of Si in a required base metal shape and heating and sintering.

Although it is known to use an Al alloy as a whetstone base metal, in the vitrified bond and the metal bond, the Al alloy melts at the heating temperature for forming the abrasive grain layer. Alternatively, the abrasive grain layer is adhered and fixed to a base made of Al sintered alloy. However, this base metal is low in strength and has a large difference in coefficient of thermal expansion from the abrasive layer, which makes it difficult to put it into practical use and the steel base metal was used as described above.

As a high-strength Al sintered alloy, Japanese Patent Laid-Open No.
-97447 proposes Si of 8 to 30% by weight, but it requires equipment such as external stress (hot extrusion) within the sintering temperature range for production, and it requires a metal base for grinding wheels. Is not used as.

In the present invention, by further increasing the addition amount of Si as described above, the thermal expansion coefficient is reduced, and an Al sintered alloy base metal having a high Young's modulus is obtained by an ordinary sintering method. To do.

Since a base metal having high strength and high dimensional accuracy is produced by ordinary hot pressing or hot sizing without requiring special equipment, it is more preferable to add the small amount of the additive metal and sinter. The temperature is also limited to within ± 80 ° C of the eutectic point temperature of the alloy powder.

Further, as shown in FIG. 2, if a preformed vitrified bond superabrasive grain layer 1 is adhered and fixed to the outer periphery of a base metal 2 formed by sintering through a base layer 5, it is lightweight and can be ground. Super-abrasive whetstone for cams with high performance can be made. In some cases, the base layer 5 can be omitted.

On the other hand, as shown in FIG. 1, the base metal 2 is directly contacted with the outer peripheral edge of the filling of the Al alloy powder to form the metal bond superabrasive grain layer 3, which is bonded to the abrasive grain powder. It is also possible to form a grindstone by arranging a mixture with a metal powder and simultaneously sintering one body. In this case, production efficiency is good

[0011]

EXAMPLES Two kinds of Al alloy powders shown in Table 1 were sintered under the sintering conditions shown in Table 2 to prepare a base metal. The particle sizes of the above powders are as shown in Table 3.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

The shape and dimensions of the sintered body are as shown in Table 4. The finished dimensions in the table are those obtained by cutting the sintered body. In addition, as shown in the table, a trial production of an abrasive grain layer fixed to a sintered body obtained by this cutting process was also performed.

[0016]

[Table 4]

Table 5 shows 3 of A, B and C sintered using the Al alloy powder of composition No. 1 into the shape and dimensions of sample No. 3.
These are the results of measuring the physical properties of individual pieces.

[0018]

[Table 5]

Table 6 shows conventional steel (S25C), cast aluminum
Alloy (Al-10% Si based alloy) and Example alloy (Composition No.
It shows a physical property comparison with 1). The values of the example alloys are average values of A, B and C in Table 5.

[0020]

[Table 6]

As can be understood from Tables 5 and 6, the alloys of the examples of the present invention have a significantly lower coefficient of thermal expansion and a higher Young's modulus than conventional Al alloys. Of course, its weight is about 1/3 compared to steel.

As shown in FIG. 2, sample No. 4 has a vitrified bond superabrasive grain layer 1 fixed on the outer peripheral edge of a sintered base metal 2 that has been cut through a base layer 5.
Sample No. 7 should have the base metal 2 formed as shown in FIG.
This is a grindstone in which one alloy powder and a mixture of 40% by weight of Cu—Sn binder powder for forming the metal bond superabrasive grain layer 3 directly contacting the outer peripheral edge thereof are sintered together.

The grindstones shown in FIGS. 1 and 2 are mounted on a rotary tester, respectively, and the speed is 160 m / s (8730 rpm) and 120 m / s (6550rp).
After rotating for 5 minutes at m), the presence or absence of cracks was checked by the dye penetrant flaw detection method, but no cracks were found in any of them.

Table 7 is a mathematical expression showing the state of stress and displacement acting on the base metal during grinding rotation. The maximum stress calculated for each base metal of Table 6 based on this formula is shown in FIG. 4, the displacement due to heat is shown in FIG. 5, and the combined displacement of rotation and heat is shown in FIG. The bar graph in FIG. 3 represents tensile strength. FIG. 7 is a table in which the displacement amounts of the steel base metal and the sample No. 4 base metal were measured under the following transfer conditions and only the grinding wheel peripheral speed was changed. Transfer conditions Transfer material FC20 (raw) Diameter 80 mm, length 230 Grindstone peripheral speed Vs = 30, 60, 80, 100 m / s Work peripheral speed Vw = 25 m / min (Nw = 100r
pm) Depth of cut Vf = φ0.24 mm / min Depth of cut A = φ0.040 mm Spark out 3 sec (5 rotations of workpiece)

[0025]

[Table 7]

As is clear from the above figures, the sample No. of the example is lighter than the conventional steel base metal, the maximum stress acting during rotation is small, and the conventional Al
Less displacement due to heat than alloys. Therefore, the rotational stress during the grinding rotation and the displacement due to the grinding heat are smaller than those of the conventional products.

Therefore, at least 60 m as in cam grinding.
/ S or more, usually 80 m / s or more at high speed and diameter 2
In the grinding process performed with a relatively large grindstone of about 00 mm or more, the deterioration of the processing accuracy due to the displacement of the base metal is significantly reduced. Incidentally, the outer diameter displacement of sample No. 4 at a peripheral speed of 80 m / s was 4 μm less than that of the steel base metal of the same shape and dimension.

In some examples, some sample Nos. Did not describe individual physical properties, but the sampling tests showed similar tendencies. In addition, although each of the added metals described above has an effect of improving the mechanical strength and the like, there is no problem even if it is not described, and the sintering atmosphere is H.
Instead of the reducing atmosphere, such as _2, it is also possible to use a neutral atmosphere or a mixed atmosphere thereof, such as N _2.

[0029]

The base metal of the present invention has a coefficient of thermal expansion equivalent to that of a conventional steel base metal, has a high specific Young's modulus, and is sufficiently practical for manufacture and use. Furthermore, since it is light and does not rust, it has good workability, and in particular has the feature that the processing accuracy can be improved as described above. An immersion test of a grinding fluid was also conducted, but there was no concern about corrosion.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a grindstone for explaining the configuration of an embodiment.

FIG. 2 is a similar partial cross-sectional view illustrating another embodiment.

FIG. 3 is a chart showing the maximum stress acting on a base metal during rotation.

FIG. 4 is a chart showing a displacement of a base metal caused by rotation during rotation.

FIG. 5 is a chart showing displacement of a base metal caused by an increase in temperature.

FIG. 6 is a chart showing the displacement of the base metal caused by rotation and temperature rise during rotation.

FIG. 7 is a table showing the measured values of the radial displacements of the example grindstone and the steel base metal grindstone when only the grindstone peripheral speed is changed in the grinding test.

[Explanation of symbols]

 1 Vitrified Super Abrasive Layer 2 Sintered Al Alloy Base Metal 3 Metal Bond Super Abrasive Layer 4 Base Metal Shaft Hole 5 Base Layer

Claims (5)

[Claims] 1. Al as a main component, containing 35% by weight or more of Si or Si containing Fe, Cu, Mg, Mn, Zn and N.
A base metal for a grindstone, which is formed by sintering an alloy powder containing at least one of i and Cr. 2. The base metal according to claim 1, wherein the grindstone is a super-abrasive grain rotary grindstone having a diameter of 200 mm or more, and the grinding with the grindstone is performed at a peripheral speed of 60 m / s or more. 3. Al as a main component, containing 35% by weight or more of Si or Si with Fe, Cu, Mg, Mn, Zn, N
A step of filling at least the alloy powder into an alloy powder formed by adding at least one of i and Cr into a base metal mold, and a step of heating to a temperature within a eutectic point temperature of ± 80 ° C. and sintering. A method for manufacturing a base metal for a grindstone, which comprises: 4. The base metal according to claim 1, or claim 3.
A superabrasive grindstone, characterized in that a vitrified abrasive grain layer is fixed to the outer peripheral edge of a base metal manufactured by the method described above, either directly or through an intermediate layer. 5. Al as a main component, containing 35% by weight or more of Si or Si containing Fe, Cu, Mg, Mn, Zn and N.
A step of filling at least the alloy powder into an alloy powder formed by adding at least one of i and Cr into a base metal mold, and a mixed powder of superabrasive grains and a binder in direct contact with the filler. A method for manufacturing a superabrasive grindstone, which comprises a step of filling and a step of heating both of the fillers to a temperature within a eutectic point temperature of the Al alloy powder ± 80 ° C to sinter them into one body.