JPH09155745A - Super abrasive grain wheel and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly mount and fix a super-abrasive grain layer on a ceramics reinforced aluminum alloy pedestal wherein a matrix is formed by means of an intermetallic compound resulting from a reaction between aluminum and ceramics. SOLUTION: When a matrix is forced by means of an intermetallic compound, melting point of a ceramics reinforced aluminum alloy pedestal increases, whereby it is possible that an abrasive grain layer is directly mounted on the aluminum alloy pedestal, which was not realized previously. This makes it possible to obtain a lightweight super abrasive grain wheel which reduces a load of a spindle motor, has a high specific tensile strength, and enhances an adhesive strength between the pedestal and the abrasive grain layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superabrasive grain wheel having an abrasive grain layer fixed to a base metal, which is used for various grinding operations of cemented carbide, ceramics, glass, tool steel and the like.

[0002]

2. Description of the Related Art A super-abrasive wheel used at high speed is subjected to the maximum stress around the mounting hole, and therefore is usually broken when the surrounding strength of the mounting hole reaches the breaking strength of the base metal material. For this reason, the superabrasive wheel has the strength of a base metal that is less likely to be damaged, the weight of the wheel that does not burden the grinder,
Further, it is required to be inexpensive and easily manufactured.

Superabrasive wheels are classified into resin bond wheels, metal bond wheels, vitrified bond wheels and the like depending on the type of binder. Resin bond wheels that use resin-based binders have a low elastic modulus,
Leveraging the low-strength characteristics, it provides a sharp and rich finished surface. Further, a metal bond wheel using a metal-based binder has a long wheel life and good dimensional accuracy of a workpiece by utilizing the characteristics of high elasticity and high strength. Vitrified bond wheels that use glass-based binders
Utilizing the characteristics of high elastic modulus and low strength, it has excellent sharpness and good dimensional accuracy of processed products.

In such a superabrasive wheel, due to the recent demand for improvement in machining efficiency and machining accuracy, the conventional peripheral speed of about 30 m / sec is increased to a higher speed of 60 to 60.
Development of materials capable of withstanding about 200 m / sec has been required.

In the latter half of the 1960's, practical machines for high-speed grinding machines were announced. In particular, Sheffield Co.
A wheel with an outer diameter of 760 mm was used to achieve a peripheral speed of 90 m / sec. An ultra-high speed grinding machine with a wheel peripheral speed of over 150 m / sec was put into practical use in the 1990s,
As of 1995, Toyoda Machinery used a wheel with an outer diameter of 250 mm for 160 m / sec, and Mitsubishi Heavy Industries an outer diameter of 38 mm.
A 200 m / sec grinder was put into practical use with a 0 mm wheel. 200m / s due to further improvement of grinder
It seems that the practical use of the peripheral speed exceeding ec is near.

When the superabrasive wheel is rotated, the centrifugal force rapidly increases in proportion to the square of the rotation speed, which increases the risk of deformation and damage of the alloy and the abrasive layer. For this reason, it is of course necessary to use a high-strength abrasive layer for the super-abrasive wheel for high-speed grinding, to secure the adhesive strength between the abrasive layer and the base metal, and especially to ensure the safety of the base metal itself. It becomes important to do.

As a countermeasure for this, a high strength material obtained by heat treating an aluminum alloy or a steel material is used as the base metal material, and in order to improve the adhesive strength between the base metal and the abrasive grain layer, the formation of the abrasive grain layer and the base metal A so-called direct attachment method, in which the adhesion and the adhesion are performed at the same time, is adopted.

However, since alloy steel has a heavy wheel weight, there is no particular problem in the case of low speed rotation,
In order to rotate this at a high speed, it is necessary to dramatically increase the spindle rigidity of the grinder and the output of the spindle motor, which is not practical.

In order to solve such a drawback, a method of using a fiber reinforced plastic such as carbon fiber reinforced thermosetting plastic (hereinafter referred to as CFRP) having a high specific strength as a material of the base metal is disclosed in Japanese Patent Laid-Open No. It is disclosed in Japanese Patent Publication No. 91541 and Japanese Patent Laid-Open No. 6-91542.

[0010]

Since this CFRP uses a resin such as epoxy having a heat distortion temperature of 130 ° C. as a matrix, it is directly attached to the base metal by baking and bonding at the same time as forming the abrasive grain layer. When the method is used, CFRP is thermally deteriorated by heat during sintering, the adhesive force between the abrasive grain layer and the base metal is weakened, and the strength of the CFRP base metal itself is reduced.
As a result, it becomes unsuitable for high-speed rotation.

For example, when the abrasive grain layer is a metal bond, the sintering temperature is about 650 to 1300 ° C., the vitrified bond is about 700 to 900 ° C., and the polyimide resin bond is about 350 to 500 ° C. Resin bond press molding pressure is 350-700MP
Since a and CFRP are deformed at a high pressure, it is difficult to form the abrasive grain layer by directly attaching to the CFRP base metal as described above.

As a countermeasure against this, when a CFRP base metal is used, the direct manufacturing method is not used and the conventional manufacturing method is used.
A method of forming the abrasive grain layer into a chip shape in advance and adhering it to the base metal is considered. According to this, it is lightweight CFR
The abrasive grain layer can be bonded to the CFRP base metal while utilizing the advantage of P. However, it is difficult to manufacture the curvature of the base metal and the chip with high accuracy because the chip is deformed or contracted during firing of the abrasive grain layer to change the dimensions. The thickness of the adhesive layer of the layers varies, and the adhesive strength becomes unstable. There is also a problem that the processing time becomes long and the manufacturing cost becomes high.

Further, Japanese Patent Laid-Open No. 3-104566 discloses that
Although a grindstone made of a silicon carbide ceramic fiber reinforced aluminum base metal having excellent specific strength and strength capable of withstanding a high peripheral speed is disclosed, even in the silicon carbide ceramic fiber reinforced aluminum alloy disclosed in the publication, its melting point is also disclosed. Is about 6
50 ° C., which is low with respect to the sintering temperature of the abrasive layer, and has the above-mentioned CF
The same problem as PR occurs, and it is difficult to adopt the direct attachment method which is excellent in the adhesive force between the base metal and the abrasive grain layer.

Therefore, the problem to be solved by the present invention is to utilize the characteristics of a ceramic-reinforced aluminum alloy base metal having an excellent specific strength, and to enable the direct attachment of an abrasive layer to the base metal. is there.

[0015]

In order to solve the above-mentioned problems, the superabrasive wheel of the present invention is a ceramic-reinforced aluminum alloy base metal in which a matrix is formed by an intermetallic compound in which aluminum reacts with ceramics. The super abrasive grain layer is fixed by direct attachment. As a result, it is possible to obtain a lightweight base metal having no quality deterioration or deformation at the sintering temperature of metal bond, vitrified bond, or polyimide resin bond.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The superabrasive grain wheel of the present invention is such that a superabrasive grain layer is fixed by direct attachment to a ceramics-reinforced aluminum alloy base metal in which a matrix is formed by an intermetallic compound in which aluminum and ceramics have reacted. It was done.

Here, the intermetallic compound
mpound) is a compound formed by combining two or more kinds of metal and non-metal elements in a simple integer ratio, and shows unique physical and chemical properties different from the constituent metal elements. Aluminum and ceramics It is produced by reacting and at a high temperature. Since the intermetallic compound obtained by the reaction of aluminum and ceramics has a high melting point, the melting point of the entire composite material is also high, which allows the melting point to be increased while utilizing the characteristics of the ceramic-reinforced aluminum alloy base metal. You can

In the present invention, a high pressure casting method is employed to obtain an intermetallic compound by reacting aluminum and ceramics. Specifically, a ceramic fiber preform is placed in a mold, and an aluminum melt is cast into the mold at a pressure of 3 to 10 MPa. As a result, the ceramics in the mold react with the molten aluminum to produce an intermetallic compound. Conventional aluminum and other metals,
The crucible method, which is generally used for reacting non-metals to produce intermetallic compounds, causes defects such as gas cavities, shrinkage cavities, and nonuniformity of the structure. Since a high pressure is applied until the molding is completed, the casting is obtained without such defects. At that time, if the casting pressure is less than 3 MPa, gas cavities, shrinkage cavities, and nonuniformity of the structure are likely to occur, and if it exceeds 10 MPa, there is a problem in equipment such as a special mold is required, which is not preferable. This gives a melting point of 1200-13
A ceramics-reinforced aluminum alloy having a temperature of 00 ° C. or higher can be obtained.

As ceramics, aluminum borate, alumina, silicon carbide, silicon nitride, zinc oxide,
Fibers of one kind or two or more kinds of magnesium oxide and potassium titanate can be used. Especially by using fibrous ones,
Increases the strength of the material. Also, the ceramic fiber is
It is desirable that the length is 10 to 30 μm and the diameter is 0.5 to 1.0 μm. If the length or diameter is out of the above range, the strength of the material becomes low, which is not preferable.

In order to investigate a resin bond wheel suitable for use at a high peripheral speed, a polyimide resin resin bond abrasive consisting of 37% by volume of polyimide resin, 24% by volume of copper powder and 39% by volume of nickel-coated diamond abrasive grains. Layer A and aluminum alloy castings, carbon steel for machine structures, chrome molybdenum steel (tempered material), ceramic fiber reinforced aluminum alloy of high pressure casting method, CFRP (see Table 1) 350mm diameter,
The stress during high-speed rotation of the resin bond wheel of JIS shape 1A1 straight cylindrical shape having a thickness of 20 mm, a central hole diameter of 30 mm, and an abrasive grain layer thickness of 3 mm was analyzed using finite element method analysis software. In this case, the tensile strength of each material and the adhesive strength between each material and the abrasive layer were determined from the test piece.

[0021]

[Table 1]

The stress applied to the wheel during high-speed rotation is around the hole diameter of the base metal, and in the abrasive grain layer, the stress σt in the tangential direction at the interface with the base metal is the maximum, and therefore analysis is focused on this point. went. Using this condition, the peripheral speed is 100m / s
Assuming that it is used in ec, referring to the standard of JIS general grindstone, with a safety factor of 2, the stress when rotating at a peripheral speed of 200 m / sec which is twice the maximum peripheral speed was analyzed. Table 2 shows the results.

[0023]

[Table 2]

As a result of considering the safety factor of the base metal for each base metal material (see Table 3), the safety factor of the base metal of the conventional aluminum alloy casting and carbon steel for machine structure is about 3. In addition, the safety factor of base metal of chrome molybdenum steel material (tempered material) and ceramics fiber reinforced aluminum alloy of high pressure casting method is 7-
It is as high as about 9. Especially, the safety factor of CFRP is 15
The degree is outstanding.

[0025]

[Table 3]

As a result of considering the adhesive strength of the abrasive grain layer for each base metal material (see Table 4), the adhesive strength of the abrasive grain layer of the conventional carbon steel for machine structure and chrome molybdenum steel (tempered material) The safety factor is about 40. Further, the safety factor of the adhesive strength of the ceramics fiber reinforced aluminum alloy produced by the high pressure casting method is as high as about 60.

[0027]

[Table 4]

The results show that aluminum alloy castings and CF
With RP, direct attachment itself was not possible and it was not a target for comparison, and a clear superiority was observed in the product of the present invention.

[0029]

【Example】

[Example 1] A cylindrical base metal of ceramic fiber reinforced aluminum alloy of high pressure casting method having an outer diameter of 344 mm was used as a core die, and this was used as a core outer die and a center of a die composed of two punches. The powdery abrasive grain layer raw material consisting of 37% by volume of polyimide resin, 24% by volume of silicon carbide, and 39% by volume of nickel-coated diamond abrasive grains is filled in the gap arranged at, and pressed with a punch at 1 MPa to press 500
Heated to ° C. Then 350 MPa for this mold
Molding was carried out by applying pressure for 30 minutes. After that, the mold was cooled to 50 ° C., and the molded product was taken out.

As a result, a resin bond wheel was obtained in which an abrasive grain layer was formed on the outer periphery of a base metal of various materials and baked and adhered at the same time.

For comparison, the outer peripheral curvature is 175 m.
m, an inner peripheral curvature of 172 mm, an outer die having an arcuate hole with a central angle of 15 °, and a die consisting of two pressing punches, in a gap between the polyimide resin, 37% by volume, and silicon carbide, 24% by volume.
A powdery abrasive grain layer raw material consisting of 39% by volume of nickel-coated diamond abrasive grains was filled.

Pressing the above mold by applying 1 MPa, 5
Heated to 00 ° C. Then 350M for this mold
A pressure of Pa was applied, this state was maintained for 30 minutes, and molding was performed. After that, the mold was cooled to 50 ° C., and the arc-shaped molded product was taken out.

An epoxy resin adhesive is applied to the outer periphery of a base metal having an outer diameter of 344 mm, which is made of a chromium molybdenum steel material (tempered material) shown in Table 1 and a ceramics fiber reinforced aluminum alloy of high pressure casting method. Using, curing temperature 15
Adhesion was fixed at 0 ° C. for 4 hours for curing.

As a result, two types of resin bond wheels were obtained in which the abrasive grain layer was adhered to the outer circumference of the base metal of various materials.

Three types of specifications, that is, two types of the conventional manufacturing method of molding the abrasive grain layer chip and then adhering it to the base metal, and one type of the manufacturing method of the present invention in which the abrasive grain layer chip is baked and bonded simultaneously with the molding, are specified.
A rotation test was conducted with a total of 30 wheels, 10 for each specification.

The test peripheral speed is a wheel peripheral speed of 200 m / se.
Assuming that it will be used in c, the safety factor is set to 2 and the maximum peripheral speed (J
The rotation test was performed at a peripheral speed of 400 m / sec which is twice that of IS-R6241). Table 5 shows the results.

[0037]

[Table 5]

In the conventional adhesion method wheel, there are variations in the adhesion strength among the chips, and the wheel peripheral speeds 210 to 4 are used.
At 00 m / sec, peeling of the abrasive grain layer occurred on 30 to 50% of the wheels. On the other hand, in the product of the present invention, since the adhesive strength is stable, the test peripheral speed of 400 m / se
No peeling occurred in c.

[Example 2] A cylindrical base metal having an outer diameter of 344 mm of two kinds of materials, a chromium molybdenum steel steel material (tempered material) and a ceramics fiber reinforced aluminum alloy of high pressure casting method shown in Table 1, was used as a core type, This is a powder containing 50% by volume of Cu powder, 25% by volume of Sn powder, and 25% by volume of diamond abrasive grains in a gap arranged in the center of a cylindrical outer die having an inner diameter of 350 mm and a die consisting of two punches. The raw material for the abrasive grain layer was filled, pressed with a punch, and heated to 700 ° C. by applying contact pressure. Then, a pressure of 50 MPa was applied to this mold to perform molding. As a result, a metal bond wheel was obtained in which an abrasive grain layer was formed on the outer periphery of various materials and baked and adhered at the same time.

Using this wheel, a peripheral speed of 200 m / s
Assuming that it will be used in ec, the safety factor is set to 2 with reference to JIS general grindstone regulations, and the maximum peripheral speed (J
A rotation test was performed at a peripheral speed of 400 m / sec, which is twice that of IS-R6241), and the power consumption of the spindle motor was measured. Table 6
Shows the results.

[0041]

[Table 6]

As a result, both metal bond wheels did not peel off the abrasive grain layer, but in the case of the carbon steel base metal for machine structure, deformation occurred around the holes. Regarding the power consumption during high-speed rotation, the metal bond wheel using carbon steel for machine structure as a base showed a high value of 1700W. On the other hand, the product of the present invention was 1350W.

[0043]

According to the present invention, the following effects can be exhibited.

(1) By forming a matrix with an intermetallic compound, the melting point of the ceramics-reinforced aluminum alloy base metal becomes high, which makes it impossible to directly attach the abrasive layer to the aluminum alloy base metal, which has been impossible in the past. It has become possible.

(2) As a result, a super-abrasive wheel that is lightweight, has excellent specific strength without burdening the spindle motor, and has high adhesion between the base metal and the abrasive layer can be obtained.

(3) Compared with CFRP, the ceramic fiber reinforced aluminum alloy produced by the high pressure casting method has no fiber orientation, so that the degree of freedom in design is high and the base metal is less likely to be damaged.

(4) Compared with iron-based materials, the ceramic fiber reinforced aluminum alloy of the high pressure casting method has excellent specific rigidity, so that the base metal does not expand even at high speed rotation, and the dimensional accuracy of the workpiece is secured. it can.

(5) Since the abrasive grain layer can be molded and fixed to the base metal at the same time, the variation of the adhesive strength, which is a drawback of the conventional adhesive manufacturing method, is eliminated, and the adhesive strength is stable. Further, the manufacturing process is simplified, the productivity is good, and the processing cost can be reduced.

(6) Compared with a material such as CFRP, it has a high thermal conductivity and an excellent heat dissipation property, and is not inferior to a conventional iron-based material. It can effectively remove heat and improve sharpness and life.

Claims (7)

[Claims] 1. A superabrasive grain wheel in which a superabrasive grain layer is fixed by direct attachment to a ceramics-reinforced aluminum alloy base metal in which a matrix is formed by an intermetallic compound in which aluminum reacts with ceramics. 2. The superabrasive wheel according to claim 1, wherein the melting point of the ceramics-reinforced aluminum alloy is 1200 to 1300 ° C. or higher. 3. The fibrous material of one or more of aluminum borate, alumina, silicon carbide, silicon nitride, zinc oxide, magnesium oxide, potassium titanate, and the like. The described superabrasive wheel. 4. The ceramic fiber has a length of 10 to 3
The superabrasive wheel according to claim 3, wherein the superabrasive wheel has a diameter of 0 µm and a diameter of 0.5 to 1.0 µm. 5. An aluminum and ceramics are reacted by a high pressure casting method to produce an intermetallic compound, whereby a base metal made of a ceramics reinforced aluminum alloy is formed, and thereafter a superabrasive grain is sintered on the base metal by a sintering method. A method for manufacturing a superabrasive wheel, which comprises directly forming a layer. 6. The method of manufacturing a superabrasive wheel according to claim 5, wherein the ceramic fiber according to claim 3 is used. 7. The method of manufacturing a superabrasive wheel according to claim 5, wherein the casting pressure is 3 to 10 MPa.