JP2002239916A - Grinding wheel of super-abrasive grain vitrified bond, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding wheel of super-abrasive grain vitrified bond having favorable abrasive surface conditions and a large abrasive wheel width, and a method for manufacturing the same. SOLUTION: Plurality of unit abrasive wheels 2 each comprising a super- abrasive grain layer 2a and a base layer 2b of the same bond composition integrally molded with each other are jointed to make a desired grinding wheel width. In the base layer 2b, hard grains of the same grain size with super- abrasive grains in the super-abrasive grain layer are mixed roughly at the same ratio of inclusion. Cores 3 provided with an axial hole 4 are engaged and fixed in the base layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a straight type having a large grinding wheel width (for example, 1A1 in JIS B 4131).
The present invention relates to a grindstone capable of improving the quality of a superabrasive grain vitrified bond grindstone and performing high-precision grinding, and a method of manufacturing the grindstone.

[0002]

2. Description of the Related Art As the precision of grinding increases, there is a demand for a superabrasive grain vitrified bond grindstone having a larger diameter and a larger grindstone width. Vitrified bond has poor moldability compared to resin bond and metal bond.
Since it is difficult to manufacture a large grinding wheel, a strip-shaped small chip as shown in FIG.
A method is adopted in which single or double rows are arranged on the outer peripheral surface of a grindstone base metal such as P and bonded with an adhesive. A holding layer made of a vitrified bond that does not include a superabrasive layer is provided on the bonding surface side of the chip with the base metal.

[0003]

However, attaching a large number of small chips to a grindstone base requires a considerable amount of man-hour, and also causes a large number of discontinuous gaps between the chips forming the grinding surface. Is inevitable. In addition, it is extremely difficult to adhere all of the gaps to the grindstone base at the same interval, and when the adhesive is cured, the size of the gap between the chips also varies. With such a grindstone in the state of the grinding surface, the grinding becomes unstable intermittent grinding, and vibration is applied to the machine, so that a good finished surface cannot be obtained. Furthermore, since the abrasive surface has a structure in which a large number of small chips are adhered, the adhesive is exposed in the gaps between the chips, which may cause clogging as grinding proceeds.

[0004] The present invention solves the above-mentioned problems, and is intended to bond a large number of superabrasive layer chips by integrally forming a superabrasive layer and a base layer with a bond having the same composition. It is possible to obtain a grindstone having a good grindstone width and a required grindstone width simply by laminating and bonding a plurality of grindstones formed in a unit width without requiring the grinding.

[0005]

The first feature of the present invention is as follows.
A plurality of unit grindstones formed by vitrified bonds of the superabrasive grain layer and the base layer by vitrified bonds having substantially the same composition are joined to obtain a required grindstone width. By making the superabrasive layer and the base layer vitrified bonds of approximately the same composition, it is possible to eliminate the difference in the coefficient of thermal expansion between them and to integrally mold them. Thus, it is possible to easily manufacture a grindstone having a required width without limitation on the grindstone width. .

A second feature is that hard abrasive grains having substantially the same diameter as the superabrasive grains of the superabrasive grain layer are mixed in the base layer of the unit grindstone at substantially the same content.

A third feature is that a core having a shaft hole is fitted and fixed to the base layer. By fitting the core, it is possible to reduce the weight of the grindstone and improve the strength of the grindstone.

A fourth feature is that the unit wheel has a wheel width of 4
0 mm or less.

The manufacturing method of the present invention is characterized in that a superabrasive layer and a base layer are integrally formed with a bond having substantially the same composition to form a unit grindstone, and a plurality of unit grindstones are joined to form a grindstone having a required width. And a step of fitting and fixing a core having a shaft hole to a base layer of a grindstone having a required width.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A superabrasive vitrified body of the present invention
As shown in FIG. 1, the bond whetstone is bonded to the super-abrasive layer 2a.
And the bond composition in the base layer 2b are the same.
A plurality of unit whetstones 2 integrally formed and bonded together.
The whetstone has the required width. Both bond compositions are identical
Although it is preferable to manufacture the superabrasive layer 2a,
Base abrasives and CBN abrasives.
When only vitrified bond is used, it is molded integrally
Above, there is a difference in shrinkage. Therefore, the thermal expansion of the base layer 2b
In order to make the elongation ratio close to that of the superabrasive layer 2a, the diameter is approximately the same
SiC, Al ₂O₃Hard abrasive grains such as superabrasive layer 2a
It is preferable to mix them in the base layer 2b at substantially the same content as
New means. Also, the mechanical strength of the base layer 2b side is improved.
Carbon fiber, glass fiber, alumina
There is also a means for including reinforcing fibers such as fibers.

The vitrified bond has a very poor compaction property at the time of molding as compared with a resin bond or a metal bond, and when the width of the superabrasive layer (dimension in the molding pressure direction) becomes large, the bond becomes uniform in the mold. Since it does not spread, the density of the superabrasive layer becomes non-uniform, resulting in a whetstone having uneven grinding performance. Super abrasive layer width is 40m, depending on bond composition
If it exceeds m, moldability will deteriorate. Therefore, the unit grindstone 2 should have a grindstone width of 40 mm or less, more preferably 30 mm or less.

An adhesive is applied to the side surface of the grinding wheel of the unit grinding wheel 2 and overlapped and bonded to form a grinding wheel having a required grinding wheel width. The adhesive is not particularly limited, but an epoxy resin-based adhesive having relatively high adhesive strength and excellent chemical resistance is preferable.

A plurality of unit whetstones 2 can be joined and a whetstone having a required whetstone width can be used as it is if the shaft hole is finished to a predetermined accuracy. However, the side surface of the base layer 2b made of the vitrified bond may be crushed if the flange is fixed too strongly. When the grindstone is directly attached to and removed from the spindle of the grinding machine, the base layer 2
If the hard abrasive grains mixed in b are exposed on the surface of the shaft hole, the main shaft of the grinding machine may be damaged. Similarly, in the case of attaching to the grinding machine via the flange, there is a fear that the grinding wheel mounting shaft of the flange may be damaged. In order to eliminate such a problem, the superabrasive vitrified bond grindstone of the present invention has a structure in which a core 3 having a shaft hole 4 is fitted and fixed to a grindstone as described in the embodiment. The shaft hole 4 may be provided after being fitted and fixed to the grindstone, and all means are included in the scope of the present invention.

The core material is steel, aluminum alloy, CF
Any material having mechanical strength such as RP and ceramics may be used, but a lightweight aluminum alloy or C-FRP is preferable, and a C-FRP having a small coefficient of thermal expansion is more preferable. When the core 3 is interposed, when the flange 3 is fixed, the strong core 3 is sandwiched, so that no force is applied to the base layer 2b. The outer diameter of the core 3 may be smaller than the outer diameter of the flange, but it is naturally preferable to make it larger.

The hole of the base layer 2b for fitting with the core 3 and the outer diameter of the core 3 may be fitted with a straight hole and a shaft, but since an adhesive is interposed between them, it is effective. There is an annoyance that a tolerance must be provided in consideration of the thickness of the adhesive in a range where a high adhesive force is exhibited. If the tolerance is too small, the adhesive does not intervene on the joint surface and the adhesive strength is reduced.
On the other hand, if the tolerance is too large, misalignment may occur or the thickness of the adhesive may be uneven, resulting in weak adhesive strength. Preferably, a taper surface inclined at the same angle is formed between the two, and the fitting can be performed so that the alignment does not occur and the adhesive can be formed to have a uniform thickness. If the taper angle θ is too small, there is no effect, and it is preferable to set the taper angle θ to 3 to 5 degrees because the fitting property is good.

[0016]

FIG. 1 shows an embodiment of the present invention. The six unit grindstones 2 are formed by integrally forming a superabrasive layer 2a and a base layer 2b, and are joined by an adhesive. The core 3 having the shaft hole 4 is fitted and fixed to the base layer 2b of the integrated superabrasive vitrified bond grindstone with an adhesive.

Hereinafter, a method for producing the grinding wheel of the present invention will be described. The bond composition of the superabrasive grain layer 2a and the base layer 2b of the unit whetstone 2 is as follows: 54% by weight of SiO _{2 and} 13% of Al ₂ O _3.
Wt%, B 2 _{O 3} is 10 _wt%, P 2 _{O 5} is 1.5% by weight, CaO is 3 percent by weight, MgO is 3% by weight, BaO 5
% By weight, 1% by weight of Na ₂ O ₃ , 1% by weight of K ₂ O, L
i ₂ O 3 wt%, ZrO ₂ 5% by weight, was used as the TiO ₂ is made of 0.5 wt%. Into the super-abrasive layer forming section, # 80 CBN abrasive grains are mixed so as to have a concentration of 150, and in the base layer forming section, SiC abrasive grains having substantially the same particle size as the CBN abrasive particles have a concentration degree of 150. Was mixed as follows. The bond filling part of the mold is separated by an ultra-thin partition plate, the former is filled in the superabrasive layer forming part on the outer peripheral side, and the latter is filled in the base layer forming part on the inner peripheral side, and then the partition plate is removed. After compression-molding both parts at the same time, firing at 100 to several 100 ° C. for several hours to form a unit grindstone 2 having an outer diameter of 350 mm and a thickness of 25 mm
Made individually. The thickness of the superabrasive layer 2a was 3 mm.
Six unit whetstones 2 were stacked, and an epoxy resin-based adhesive was applied and bonded between them to form a whetstone having a whetstone width of 150 mm. In this embodiment, the unit whetstones having the same size are used. However, unit whetstones having different whetstone widths may be combined.

The base layer 2b of this grindstone has a small diameter side hole diameter φ2.
A hole having a taper angle θ of 4 degrees was formed at 56 mm. To fit this, it has a shaft hole φ150mm, and 4
A core 3 made of an aluminum alloy having a tapered degree was prepared. An adhesive was applied to the tapered hole surface of the base layer 2b, and the core 3 was fitted and bonded. As shown in FIG. 1, the core 3 is made longer than the width of the grindstone so as to protrude at both ends after fitting to the grindstone. Can be flushed. Thus, a grindstone 1 having an outer diameter of 350 mm and a grindstone width of 150 mm was obtained.

As a comparative example, a chip 5 shown in FIG. 2 was manufactured under the same molding conditions as those of the example. The size of the chip 5 is 40 mm in length L, 25 mm in width W, and 3 m in thickness t.
m, the arc R1 of the attachment surface is 172 mm, and the arc R2 of the outer peripheral surface is 175 mm. Twenty-seven of these are attached to an aluminum alloy base metal having an outer diameter of 346 mm and a width of 150 mm with epoxy resin adhesive in a circumferential direction of 27 pieces in 6 rows.
A grindstone of the same size as the example was used.

Using the above-described example grindstone and comparative example grindstone,
The following grinding test was performed. (Grinding test 1) Grinding test conditions Grinding method: Centerless grinding Work material: Size φ19 × 13H × 50L Material: SCr420 Hardness: HRa80 Wheel peripheral speed: 80 m / sec. Passing speed: 2.5 m / min. Allowance: φ0.05 mm / pass Grinding fluid: Soluble The results of the grinding test are shown in Table 1.

[0021]

[Table 1]

(Grinding Test 2) Grinding Test Conditions Grinding Method: Centerless Grinding Work Material: Size φ2 × 10L Material: SUJ2 Hardness: HRc 55-58 Wheel peripheral speed: 44 m / sec. Passing speed: 9.4 m / min. Clearance: φ0.02 mm / pass Grinding fluid: JIS W Class 2 The results of the grinding test are shown in Table 2.

[0023]

[Table 2]

As described above, the grindstone of the present invention obtained better results in terms of surface roughness and accuracy than the conventional grindstone.

[0025]

According to the present invention, it is possible to easily manufacture a grindstone having a large required grindstone width by laminating and joining a plurality of unit grindstones manufactured with a grindstone width in a good formability range. Also, unlike a grindstone in which a large number of small chip chips are pasted on a grindstone base, the grinding surface condition is good, and high precision processing is possible.

[Brief description of the drawings]

FIG. 1 is a sectional view of a grindstone according to an embodiment of the present invention.

FIG. 2 is a perspective view of a conventional chip.

[Explanation of symbols]

 Reference Signs List 1 superabrasive grain vitrified bond grindstone 2 unit grindstone 2a superabrasive grain layer 2b base layer 3 core 3a core protrusion 3b core protrusion 4 shaft hole 5 tip 5a superabrasive grain layer 5b holding layer θ taper angle L tip length W Chip width t Chip thickness R1 Circular arc of chip attachment surface R2 Circular arc of chip outer peripheral surface

Claims (5)

[Claims] 1. A superabrasive grain vitrified bond grindstone characterized in that a plurality of unit grindstones formed by vitrified bonds of a superabrasive grain layer and a base layer having substantially the same composition are joined to obtain a required grindstone width. 2. The superabrasive according to claim 1, wherein hard abrasive grains having substantially the same diameter as the superabrasive grains of the superabrasive grain layer are mixed in the base layer of the unit grindstone at substantially the same content. Grain vitrified bond whetstone. 3. The superabrasive grain vitrified bond grindstone according to claim 1, wherein a core having a shaft hole is fitted and fixed to said base layer. 4. The superabrasive grain vitrified bond grindstone according to claim 1, wherein the unit grindstone has a grindstone width of 40 mm or less. 5. A step of integrally forming a superabrasive layer and a base layer with a bond having substantially the same composition to form a unit whetstone; a step of joining a plurality of unit whetstones to form a whetstone having a required width; And a step of fitting and fixing a core having a shaft hole to a base layer of the obtained grindstone.