JPH10315138A - Metal bond grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase bonding strength of an abrasive grain layer and base metal, and stably reduce grinding resistance by holding a super abrasive grain by using a bonding material containing a specific quantity of Al, and using Al alloy for a pedestal. SOLUTION: In a metal bond grinding wheel, 40% or more of the whole component of a bonding material to sinter a super abrasive grain such as a CBN abrasive grain is formed of Al. As a result, weight of a super abrasive grain layer is reduced, and a load to a grinding device is reduced, and centrifugal stress at rotating time can also be reduced, and it is particularly suitable for high peripheral speed grinding time. Base metal of the metal bond grinding wheel is composed of Al alloy, and particularly, Al-Si type alloy is suitably used since castability is excellent and a thermal expansion coefficient is small and heat resistance is excellent. Since Si is also added to the bonding material, bonding strength of the bonding material and Al alloy of the base metal can be improved at a low baking temperature, and wettability of the bonding material and the super abrasive grain is improved further, and there is no need to perform preprocessing such as copper plating on the base metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a metal bond grinding wheel. More specifically, the present invention relates to a metal-bonded grindstone that exhibits high performance as a grinding wheel for high peripheral speed, having a large abrasive grain holding force and a large bond strength with a base metal, a small stress deformation, a small grinding resistance, and a small grinding force.

[0002]

2. Description of the Related Art Conventionally, metal-bonded grindstones obtained by sintering superabrasive grains using a metal powder as a binder have been known as Cu-S
Iron-based metals have often been used for n-based metal bonds and base metals. However, a Cu-Sn-based metal bond grindstone has a high specific gravity of the whole grindstone, and it is difficult to exhibit the performance as a high peripheral speed grinding grindstone. In addition, the bonding strength of the Cu-Sn-based metal bond grindstone does not improve unless the abrasive layer and the base metal are sintered and bonded via a copper plating layer or the like. Further, the bonding strength is limited even through the copper plating layer, and cracks may be generated between the base metal and the abrasive grain layer in a severe environment of high-speed grinding. In recent years, while high peripheral speed grinding wheels are expected, it is difficult to use metal bond whetstones with such high specific gravity and uneasy about the bonding strength between the abrasive layer and the base metal,
Development of a grindstone that is lightweight and has a high bonding strength between the abrasive layer and the base metal is underway. For example, JP-A-5-8177 discloses that an aluminum alloy is used as a base metal, a spherical nickel powder is used as a binder, and an aluminum alloy is melted and formed using centrifugal force due to rotation. Hard aluminum between
A manufacturing method is disclosed in which the formation of a Ni intermetallic compound enhances the bond between the abrasive grain layer and the base metal, and at the same time reduces the weight of the grindstone itself. However, according to this manufacturing method,
Since the composition of the binder is only Ni, there is a defect that it lacks elasticity like a Cu-Sn-based metal bond and is weak against impact. In addition, for forming the alloy in the molten state by centrifugal force,
Requires special and expensive equipment. Also, Japanese Patent Laid-Open No. 7-17 / 1995
No. 1767 discloses steel-based metal bond powder and A
(1) A metal-bonded superabrasive grindstone in which the coefficient of thermal expansion between an abrasive layer and a base metal is maintained at the same level by sintering an alloy powder to improve the bonding strength between the abrasive layer and the base metal has been disclosed. I have. However, this metal-bonded grindstone uses steel-based powder as the metal bond, so there is no chemical reaction between the bonding material and the base metal, and the bonding strength is low even when the powders are sintered together. There is.

[0003]

DISCLOSURE OF THE INVENTION The present invention has a small stress deformation, a high abrasive grain holding force, a large bonding strength between an abrasive grain layer and a base metal, a light weight, a small power required for driving, and a grinding method. The object of the present invention is to provide a long-life metal bond grindstone that is stable in resistance, has a flat surface of an object to be ground, has a large grinding ratio, and is suitable for high peripheral speed grinding.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have held super-abrasive grains using a binder whose main component is Al, By using an Al alloy, it has been found that a lightweight, metal-bonded grindstone having a stable and low grinding resistance can be obtained, and the present invention has been completed based on this finding. That is, the present invention relates to (1) a metal bond grindstone obtained by sintering superabrasive grains using a metal powder as a binder, wherein 40% by weight of all components of the binder is provided.
The above is Al, and the base metal is made of an Al alloy. (2) The bonding material is Zn and S
(3) The metal bond grinding wheel according to (1), containing i.
The weight ratio of Zn in the binder is larger than the weight ratio of Si.
(2) The metal-bonded grinding wheel described in (2), and (4) an intermediate layer between the superabrasive layer and the base metal, and the material of the intermediate layer is Zn and / or
Alternatively, the present invention provides the metal bond grinding wheel according to the above (1), (2) or (3), which is an Al alloy containing Cu.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The metal bond grindstone of the present invention is a metal bond grindstone obtained by sintering superabrasive grains using a metal powder mainly composed of Al as a binder. In the present invention, any of CBN abrasive grains and diamond abrasive grains can be used as super abrasive grains. The metal bond whetstone of the present invention
At least 40% by weight of the binder for sintering the superabrasive grains is Al. As the binder, a mixture of powders of simple metals can be used, and a powder of an alloy of two or three or more metals can be used as one.
A single kind or a mixture of two or more kinds can be used, or a powder of a simple metal and a powder of an alloy can be used by mixing. Regardless of whether the binder is a simple metal or an alloy, the weight ratio of Al in the binder is determined as a ratio to all components of the binder. When the main component of the binder is Al, the superabrasive layer is reduced in weight, the wettability between the binder and the superabrasive grains is improved, and good abrasive grain retention is maintained. In the metal bond grindstone of the present invention, when 40% by weight or more of the total components of the binder is Al, the weight of the superabrasive layer is larger than that of a metal bond grindstone using a conventionally used bronze-based binder. , The load on the grinding device is reduced, and the centrifugal stress at the time of rotation can be reduced. In the metal bond whetstone of the present invention, when the ratio of Al to all components of the binder is less than 40% by weight, the wettability between the superabrasive grains and the binder is reduced, and the abrasive holding power is insufficient. There is a possibility that the toughness as a bonding material is reduced and the material is broken by deformation during rotation.

The base metal of the metal bond grindstone of the present invention is made of Al
Made of alloy. There is no particular limitation on the Al alloy used,
For example, Al-Mg based alloy, Al-Si based alloy, Al-
Cu-based alloy, Al-Cu-Mg-based alloy, Al-Cu-S
i-based alloy, Al-Cu-Ni-based alloy, Al-Cu-Mg
-Ni-based alloy, Al-Zn-Mg-based alloy, Al-Mn-based alloy, and the like. Among these, Al-
Si-based alloys can be particularly preferably used because they have good castability, a small coefficient of thermal expansion, and excellent heat resistance.
In the metal bond grinding wheel of the present invention, the binder is Al
It is preferable to contain Zn and Si in addition to the components.
There is no particular limitation on the method for incorporating Zn and Si into the binder. For example, as the binder, Al simple powder, Zn
A mixture of a simple powder and a simple Si powder, a mixture of an Al-Si alloy powder and a simple Zn powder, or an Al-Zn-
Any combination of metal simple substance and alloy such as Si-based alloy powder can be used. In the present invention, as a metal component of the binder, Cu, M
g, Fe, Mn, Cr, Ni, Ti, Sn and the like can be contained. These metal components can be added as a simple powder or as an alloy powder containing these metal components. These metal powders or alloy powders can be mixed and used so that the composition ratio of all components of the binder becomes a desired value.

[0007] By incorporating Si into the binder,
The bonding strength between the binder and the Al alloy of the base metal can be improved at a low firing temperature, and the wettability between the binder and the super-abrasive grains is further improved. It is not necessary to perform a pretreatment such as copper plating on the base metal. Further, as disclosed in JP-A-7-171767, it is possible to obtain a strong bond between the binder and the base metal by using the Al alloy powder also for the base metal. Z for binder
By containing n, an α-solid solution is formed around the sintering temperature and the brittleness of the binder is improved, and the bending strength, elastic modulus and hardness of the binder are increased, the stress deformation is reduced, and the grinding is performed. The performance is improved, a ground surface having excellent surface smoothness can be obtained, and the durability of the metal bond grindstone is improved. In the metal bond whetstone of the present invention, the strength of the binder can be adjusted by adjusting the amounts of Zn and Si contained in the binder. By adjusting the weight ratio of Zn in the whole binder to be larger than the weight ratio of Si, preferably by adjusting the weight ratio of Zn to be 1.5 to 3.6 times the weight ratio of Si. , Good results can be obtained. The weight ratio of Zn is S
When the weight ratio of i is less than 1.5 times, the density of the binder is low, but the mechanical strength of the binder is reduced, and it may be difficult to withstand the environment of high-speed grinding. If the weight ratio of Zn exceeds 3.6 times the weight ratio of Si, the bonding strength between the base metal and the Al alloy may be reduced. When the weight ratio of Zn is S
If it exceeds 3.6 times the weight ratio of i, the melting temperature will be low and a liquid phase will be formed due to the sintering with the Al alloy of the base metal, which may make molding difficult. In the metal bond grindstone of the present invention, the binder has moderate brittleness while firmly holding the superabrasive grains. Therefore, the binder is easily removed, and blindness and autogenous action are rapidly repeated. For this reason, the grinding resistance does not increase, and stable and good grinding performance is exhibited.As with a metal bond grindstone using a conventional bronze-based binder, the gap between blindness and autogenous action is long, and grinding The phenomenon of high resistance and instability does not occur. In the metal bond grinding wheel of the present invention, an intermediate layer can be provided between the superabrasive layer and the base metal. By forming the intermediate layer with a material having a high affinity for both the base metal and the superabrasive layer, it is possible to increase the bonding strength between the base metal and the superabrasive layer and to enable high peripheral speed grinding. it can. There is no particular limitation on the material of the intermediate layer,
For example, an Al alloy containing Zn and / or Cu is an Al alloy containing Zn and Si even with respect to an Al alloy of a base metal.
Since it has a high affinity for a superabrasive bonding material made of an alloy, it can be suitably used. Also, use Al
Depending on the alloy base, Mg, Fe, Mn, Cr, Ni, T
i, Sn or the like can be contained. These metal components can be added alone or as an alloy powder containing them.

In order to produce the metal bond grindstone of the present invention, a binder made of superabrasive grains and a metal powder in which at least 40% by weight of Al is Al is preferably used in an inert gas atmosphere in a ball mill or the like. Mix uniformly using. The mixing ratio of the superabrasives and the binder is preferably such that the concentration is 1 to 4.4 ct / cm ³ . The mixture of superabrasives and binder is put into a mold together with a metal base made of Al alloy, heated and pressed at a temperature below the melting point of the metal powder, and sintered to improve the mechanical strength to the required degree. Form a granular layer. A mold, a carbon mold, or the like can be used as a mold, and a muffle furnace, an induction heating furnace, a resistance heating furnace, or the like can be used for heating. FIG. 1 is a schematic diagram of a superabrasive layer of a metal bond grindstone of the present invention. By sintering a single metal powder or an alloy powder together with superabrasive grains, an α-solid solution and a silicon crystal are formed, and the superabrasive grains 1 are converted into an α-solid solution 2
And the silicon crystal 3. In order to manufacture the metal bond grindstone of the present invention having an intermediate layer, for example, an Al alloy powder, a Zn powder, a Cu powder, etc. are blended, preferably in an inert gas atmosphere, and uniformly using a ball mill or the like. The metal powder composition for the intermediate layer is prepared by mixing, and the metal powder composition for the intermediate layer is compression-molded on the working surface of the base metal made of an Al alloy. Next, the mixture of the superabrasive grains and the binder is compression-molded on the outer periphery of the molded article of the metal powder blend for the intermediate layer. Finally, it is heated and pressed at a temperature equal to or lower than the melting point of each metal powder and sintered to improve the mechanical strength to the necessary degree,
An intermediate layer and a superabrasive layer are formed to obtain a metal bond grindstone. The metal bond whetstone of the present invention has a small stress deformation,
Since the abrasive grain holding power is high and the bonding strength between the abrasive grain layer and the base metal is large, it can be suitably used for high peripheral speed grinding at a peripheral speed of 100 m / sec or more. And the grinding resistance during grinding is small and stable.

[0009]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Reference Example 1 The stress generated during rotation of the metal bond grindstone was calculated by the finite element method (FEM). FIG. 2 is a partial schematic view of a metal bond grindstone used for calculation. This metal bond whetstone has a 3 mm thick, 2.8 g / cm ³ intermediate layer, a 3 mm thick, 2.78 g density on the outer periphery of an Al alloy base metal having a diameter of 205 mm and a density of 2.7 g / cm ^3. / Cm ³ . This metal bond whetstone has a peripheral speed of 200m /
When rotating in seconds, the maximum value of the stress generated in the base metal is 61
MPa, and the position where the maximum stress was generated was the central part A of the base metal. The stress generated at the joint B between the base metal and the intermediate layer was 19 MPa, and the stress generated at the joint C between the intermediate layer and the superabrasive layer was 16 MPa. Reference Example 2 Zn powder was mixed with an Al alloy powder containing 12% by weight of Si so that the Zn contents became 10, 15, 20, 25, and 30% by weight, respectively. After these metal powder formulations were uniformly mixed using a ball mill filled with nitrogen gas, a No. A test piece specified in JIS Z 2203 was molded at a pressure of 98 MPa. The obtained test piece was
Baking was performed at 560 ° C. for 35 minutes under a pressure of 9.6 MPa, and immediately thereafter, cooling was performed for 40 minutes under a pressure of 19.6 MPa. About the obtained test piece, a universal testing machine [Shimadzu Corporation, AG
-20 kNC] to measure the bending strength and the elastic modulus. In addition, Rockwell hardness according to JIS Z 2245,
The density was measured according to JIS Z2505. The results are shown in Table 1.

[0010]

[Table 1]

The results in Table 1 show that of the tested metal powder formulations, those with a Zn content of 20 to 30% by weight have the most suitable physical properties as binder. In addition, since the metal powder blends having these compositions had good moldability, they were used as binders for CBN abrasive grains in the examples. Reference Example 3 A Zn powder or a Cu powder is blended with an Al alloy powder containing 12% by weight of Si, a composition containing 5% by weight of Zn, a composition containing 8% by weight of Zn, and a composition containing 10% by weight of Zn. And four metal powder formulations of the formulation containing 10% by weight Cu. For these metal powder formulations, test pieces were molded in the same manner as in Reference Example 2,
The transverse rupture strength, elastic modulus, Rockwell hardness and density were measured. The results are shown in Table 2.

[0012]

[Table 2]

From the results in Table 2, it can be seen that the Zn content is 8 to 1%.
It can be seen that the strength and elastic modulus show high values in the 0 wt% composition. In addition, for the above four types of metal powder blends, a joint test piece with a cast four type B aluminum alloy specified in JIS H5202 as a base metal material,
In addition, Zn alloy was added to the Al alloy powder containing 12% by weight of Si, which was selected as the binder for the CBN abrasive grains in Reference Example 2.
A joint test piece with a composition in which Zn powder was blended so as to have a content of 20% by weight was molded, and the joint strength was determined as the bending strength at the joint surface. The results are shown in Table 3.

[0014]

[Table 3]

From the results shown in Tables 2 and 3, among the tested metal powder formulations, the one having a Zn content of 8% by weight had a high strength and occurred on the joint surface obtained in Reference Example 1. Since it was found that the material had a bonding strength that could sufficiently cope with the applied stress, it was used as a material for the intermediate layer in the examples. Example 1 Zn powder was blended with Al alloy powder containing 12% by weight of Si so that the Zn content was 20% by weight, and CBN abrasive grains having a particle size of # 140/170 were concentrated at a concentration of 2.2 ct / cm ^3. It was blended so that This powder formulation was uniformly mixed using a ball mill filled with nitrogen gas. Using a base metal made of an aluminum alloy (AC4B), the powder formulation was molded at a pressure of 98 MPa, then baked at 560 ° C. under a pressure of 19.6 MPa for 35 minutes, and then immediately at 19.6 M
After cooling for 40 minutes under a pressure of Pa, a CBN abrasive layer was formed. Furthermore, by grinding, 200D-6W-3X-
A 50.8H metal bond whetstone was completed. Using this metal bonded grinding wheel, the workpiece SKS3 (H _R C60)
With a wheel peripheral speed of 120 m / s and a table speed of 15 m / s
The grinding was performed under the conditions of a minute, a cut amount of 25 μm, a grinding width of 3 mm, a grinding style plunge (up-cut) grinding, and a grinding solution chemical solution type. Comparative Example 1 CBN having a particle size of # 140/170 was added to a bronze alloy powder.
Abrasive grains were blended to give a concentration of 2.2 ct / cm ³ . This powder formulation was uniformly mixed using a ball mill filled with nitrogen gas. 1 on the adhesive layer of the base metal of S55C
After applying 0μm copper plating, 6MPa under pressure of 20MPa
Baking at 00 ° C. for 40 minutes to form a CBN abrasive layer, and further grinding, 200D-6W-3X-50.8H
Completed a metal bond whetstone. Using this metal bond whetstone, the work material SKS3 was ground in the same manner as in Example 1. Table 4 and FIG. 3 show the relationship between the grinding amount and the grinding resistance for Example 1 and Comparative Example 1, and Table 5 shows the wheel wear and surface roughness when the grinding amount is 27 cm ³ .

[0016]

[Table 4]

[0017]

[Table 5]

From the results shown in Table 4 and FIG. 3, it can be seen that the metal-bonded grindstone of the present invention has a stable grinding resistance for a long period of time. On the other hand, the conventional metal-bonded grindstone of Comparative Example 1 has a small grinding resistance immediately after the start of grinding, but the grinding resistance gradually increases as the grinding amount increases, and is unstable. Example 2 Zn powder was blended with Al alloy powder containing 12% by weight of Si so as to have a Zn content of 10% by weight, and uniformly mixed using a ball mill filled with nitrogen gas to obtain a metal powder for an intermediate layer. A formulation was prepared. Further, Zn powder was blended with an Al alloy powder containing 12% by weight of Si so that the Zn content became 20% by weight, and C particles having a particle size of # 140/170 were further added.
BN abrasive grains are blended to a concentration of 2.2 ct / cm ³ and uniformly mixed using a ball mill filled with nitrogen gas.
A powder formulation for a BN abrasive layer was prepared. Using a base metal made of an aluminum alloy (AC4B), the metal powder composition for the intermediate layer is molded at a pressure of 98 MPa, and then CB
After molding the powder composition for N abrasive layer at a pressure of 98 MPa, it is baked at 560 ° C. for 35 minutes under a pressure of 19.6 MPa,
Immediately thereafter, it was cooled for 40 minutes under a pressure of 19.6 MPa,
An intermediate layer and a CBN abrasive layer each having a thickness of 3 mm were formed. Furthermore, by grinding, 200D-6W-3X
A metal bond whetstone of -50.8H was completed. Using this metal bonded grinding wheel, the workpiece SKS3 (H _R C60)
Wheel speed 80 m / sec, 120 m / sec, 160 m
The grinding was performed under the following conditions: / m or 200 m / sec, table speed 15 m / min, depth of cut 45 μm, grinding width 3 mm, grinding style plunge (up-cut) grinding, grinding fluid chemical solution type. Table 6 and FIG. 4 show the relationship between the grinding amount and the grinding resistance at each wheel peripheral speed.
Wheel wear depth when the m ³ shown in Table 7.

[0019]

[Table 6]

[0020]

[Table 7]

From the results shown in Table 6 and FIG. 4, in the metal-bonded grinding wheel of the present invention, the grinding resistance decreases as the wheel peripheral speed increases, but under constant grinding conditions, the grinding resistance is stable for a long period of time. You can see that. Also, from the results in Table 7, it can be seen that as the wheel peripheral speed increases, the wear depth of the wheel decreases.

[0022]

The metal-bonded grindstone of the present invention has a small stress deformation, a high abrasive grain holding power, a large bonding strength between the abrasive layer and the base metal, a light weight, a low power required for driving,
Grinding resistance during grinding is small and stable.

[Brief description of the drawings]

FIG. 1 is a schematic view of a superabrasive layer of a metal-bonded grindstone of the present invention.

FIG. 2 is a partial schematic view of a metal bond grindstone to be calculated;

FIG. 3 is a graph showing a relationship between a grinding amount and a grinding resistance.

FIG. 4 is a graph showing a relationship between a grinding amount and a grinding resistance.

[Explanation of symbols]

 1 superabrasive grains 2 α-solid solution 3 silicon crystal

Claims (4)

[Claims] 1. A metal bond whetstone obtained by sintering superabrasive grains using a metal powder as a binder, wherein at least 40% by weight of all components of the binder is Al, and the base metal is made of an Al alloy. Metal bond whetstone. 2. The metal bond grinding wheel according to claim 1, wherein the binder contains Zn and Si. 3. The metal bond grinding wheel according to claim 2, wherein the weight ratio of Zn in the binder is larger than the weight ratio of Si. 4. The intermediate layer between the superabrasive layer and the base metal, wherein the material of the intermediate layer is an Al alloy containing Zn and / or Cu. Metal bond whetstone.