JP2835425B2 - Grinding wheel base, superabrasive grindstone, and methods for producing them - 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 for grinding various materials and parts, particularly a high-speed grinding wheel such as a cam grinding wheel, and a base for the grinding wheel.

[0002]

2. Description of the Related Art Generally, vitrified grindstones and metal bond grindstones, which use vitrified or metal as a bonding material for superabrasive grains, have a strong gripping force for the abrasive grains and a high bond strength, are generally used as such kind of grindstones. . And, a high strength steel is used as a base metal in these whetstones.

[0003]

The steel base is
Despite the above advantages, there is a disadvantage that it is heavy and easily rusts. In particular, in the case of a large grinding wheel such as a grinding wheel for cam grinding, workability is poor due to its weight, and a rigid grinding equipment for high-speed rotation is required. In addition, there remains a problem that the radius of the base metal is displaced due to the rotation and temperature rise of the grindstone during grinding, thereby lowering the processing accuracy.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the first feature of the present invention is that a base for a grindstone is mainly composed of Al. An alloy powder obtained by adding 35 % by weight or more of Si excluding 35 % by weight is filled in a required base metal shape, and then heated and sintered.

[0005] It is known that an Al alloy is used as a grindstone base. However, in a vitrified bond and a metal bond, the Al alloy is melted at the heating temperature for forming the abrasive layer, so that a previously prepared Al casting alloy is used. Alternatively, the abrasive layer is formed by bonding and fixing an abrasive layer to a base metal made of an Al sintered alloy. However, this metal base has a low strength and a large difference in thermal expansion coefficient from that of the abrasive layer, so that it is difficult to use the metal base, and a steel metal base is used as described above.

As a high-strength Al sintered alloy, Japanese Patent Application Laid-Open
No.-97447 proposes a material with 8 to 30% by weight of Si, but it requires equipment such as the need to apply external stress (hot extrusion) within the sintering temperature range for production, Not used as.

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

[0008] In order to produce a base metal having high strength and high dimensional accuracy by ordinary hot pressing or hot sizing without any special equipment, it is more preferable to add the small amount of additive metal and sinter the metal. The temperature is also intended to be limited to within ± 80 ° C. of the eutectic point temperature of the alloy powder.

As shown in FIG. 2, if a previously formed vitrified bond superabrasive layer 1 is adhered and fixed via a base layer 5 to the outer periphery of a base metal 2 formed by sintering, a lightweight and ground material can be obtained. Super-abrasive grinding wheels 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 metal alloy super-abrasive layer 3 is to be formed directly on the outer peripheral edge of the filler of the Al alloy powder on which the base metal 2 is to be formed. It is also possible to arrange a mixture with the metal powder and simultaneously sinter one body to form a grindstone. In this case, production efficiency is good

[0011]

EXAMPLES Two types of Al alloy powders shown in Table 1 were sintered under the sintering conditions shown in Table 2 to produce base metals. The particle size of the powder is as shown in Table 3.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

Table 4 shows the shape and dimensions of the sintered body. The finished dimensions in the table are obtained by cutting the sintered body. Further, as shown in the table, a trial production of a sintered body having the abrasive grain layer fixed to the sintered body subjected to the cutting process was also performed.

[0016]

[Table 4]

Table 5 shows that samples A, B, and C were sintered to the shape and dimensions of sample No. 3 using an Al alloy powder of composition No. 1.
It is the result of having measured each physical property about an individual.

[0018]

[Table 5]

Table 6 shows conventional steel (S25C), casting Al
Alloy (Al-10% Si based alloy) and Example alloy (Composition No.
It shows a comparison of physical properties with 1). The values of the alloys of the examples 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 according to the examples of the present invention have a significantly reduced coefficient of thermal expansion and a high Young's modulus as compared with conventional Al alloys. Of course, its weight is about 1/3 compared to steel.

As shown in FIG. 2, the sample No. 4 has a vitrified bond superabrasive layer 1 fixed on the outer peripheral edge of the cut sintered base metal 2 via a base layer 5.
Sample No. 7 has a base metal 2 to be formed as shown in FIG.
1 is a grindstone obtained by simultaneously sintering a mixture of 1 alloy powder and a binder powder of 40% by weight of Cu-Sn to form a metal-bonded superabrasive layer 3 disposed directly on the outer peripheral edge thereof.

Each of the whetstones shown in FIGS. 1 and 2 is mounted on a rotation tester, and is set at 160 m / s (8730 rpm) and 120 m / s (6550 rp).
After rotating for 5 minutes in m), the presence or absence of cracks was checked by the dye penetrant flaw detection method, but none of them was cracked.

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

[0025]

[Table 7]

As is clear from the above figures, the sample according to the sample No. of the embodiment is lighter than the conventional steel base metal, has a smaller maximum stress acting upon rotation, and has a lower Al stress.
Less displacement by heat compared to alloys. Accordingly, the rotational stress during the grinding rotation and the displacement due to the grinding heat are smaller than any of the conventional products.

Therefore, at least 60m as in the case of cam grinding
/ S, usually 80m / s or more, and diameter 2
In grinding performed with a relatively large grindstone of about 00 mm or more, a decrease in processing accuracy due to 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 smaller by 4 μm than that of a steel base metal having the same shape and dimensions.

In some of the examples, the individual physical properties were not described according to the sample No., but the same tendency was shown in the sampling tests. Each of the added metals described above has an effect of improving the mechanical strength and the like, but any other metal may be used.
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, a high specific Young's modulus, and has sufficient practicality in production and use. Further, since it is light and does not rust, it has good workability, and in particular, has a feature that processing accuracy can be improved as described above. A grinding liquid immersion test was also performed, but there was no concern about corrosion or the like.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a part of a grindstone for explaining a configuration of an embodiment.

FIG. 2 is a similar one-part longitudinal sectional view illustrating another embodiment.

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

FIG. 4 is a table showing displacement caused by rotation generated in a base during rotation.

FIG. 5 is a table showing displacement of a base metal caused by a rise in temperature.

FIG. 6 is a table showing displacements caused by rotation and temperature rise of the base during rotation.

FIG. 7 is a table showing actual measured values of 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]

 DESCRIPTION OF SYMBOLS 1 Vitrified superabrasive layer 2 Sintered Al alloy base metal 3 Metal bond superabrasive layer 4 Shaft hole of base metal 5 Base layer

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-171767 (JP, A) JP-A-2-65974 (JP, A) JP-A-57-178667 (JP, A) (58) Investigation Field (Int. Cl. ⁶ , DB name) B24D 3/00 340 B24D 5/00

Claims (5)

(57) [Claims] (1) Mainly Al , excluding 35% by weight.
Fe in Ku 35 wt% or more of Si or Si, Cu, M
A base for a grinding wheel, comprising sintering an alloy powder to which at least one of g, Mn, Zn, Ni, and Cr is added. 2. A grindstone is a superabrasive rotary grindstone having a diameter of 200 mm or more, and a grinding speed by the grindstone is 60 m / s.
2. The method according to claim 1, wherein the above is performed.
The stated deposit. 3. Mainly Al , excluding 35% by weight.
Fe in Ku 35 wt% or more of Si or Si, Cu, M
a step of filling at least the alloy powder into an alloy powder to which at least one of g, Mn, Zn, Ni, and Cr is added, and heating to a temperature within a eutectic point temperature ± 80 ° C. And a sintering step. 4. A vitrified abrasive layer fixed directly or via an intermediate layer to an outer peripheral edge of a base metal according to claim 1 or 2 or a base metal manufactured by the method according to claim 3. Characterized by super abrasive grains. 5. Mainly Al and excluding 35% by weight.
Fe in Ku 35 wt% or more of Si or Si, Cu, M
at least one of g, Mn, Zn, Ni and Cr added to an alloy powder, and at least the alloy powder is filled in a die. A superabrasive process comprising the steps of filling a mixed powder of a binder and heating both fillers to a temperature within the eutectic point temperature of the Al alloy powder ± 80 ° C and sintering them together. Manufacturing method of grain whetstone.