JPH0890427A - Duplex surface grinding wheel - Google Patents

Abstract

PURPOSE: To prolong the life cycle of a duplex surface grinding wheel by increasing, within a specified range, the percentage of crystallitic sintering aluminum abrasive particles contained in abrasive particles on the grinding plane as closer it gets to the outer circumference of the grinding wheel. CONSTITUTION: The percentage of crystallitic sintering alumimun abrasive particles contained in abrasive particles on the grinding plane 12 of a duplex surface grinding wheel 10 is set higher within the range of 10 to 70 volume percent as it gets closer to its outer circumference portion 16 side. For example, an outer circumference 16 of high peripheral speed and heavy grinding load is composed of 41 volume percent of abrasive particles, 35 volume percent of epoxy resin functioning as a resin bond, and the rest of the volume with pores. 70% of the volume of the abrasive particles is formed of crystallitic sintering aluminum of a submicron size. Although the inner circumference portion 18 is also similarly composed of 41 volume percent of abrasive particles, 35 volume percent of resin bond and the rest with pores, 100% of the abrasive particle volume is formed by a white alundum WA.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided surface grinding wheel.

[0002]

2. Description of the Related Art A double-sided surface grinding wheel is known which cuts both sides of a work material by passing the work material between a pair of grinding surfaces that face each other. In order to maintain the processing accuracy of the work material, it is desired that the grinding plane of the double-sided surface grinding wheel be flat.

[0003]

However, the above-mentioned double-sided surface grinding wheel is generally constructed by bonding general abrasive grains such as fused alumina abrasive grains and silicon carbide abrasive grains by resinoid bond, and the grinding plane is Since the peripheral speed is higher and the grinding load is larger toward the outer peripheral portion, the flatness is impaired due to wear earlier than in the central portion. Therefore, the dressing interval for obtaining flatness again is short, and the dressing amount is small. However, it has a shortcoming that the life of the grindstone is short.

On the other hand, it is conceivable to construct a double-sided surface grinding wheel by using microcrystalline sintered alumina abrasive grains having excellent grinding performance. In such a case, the whole area of the double-sided surface grinding wheel is considered. Since the microcrystalline sintered alumina-based abrasive grains are mixed in a similar ratio, the grinding stone is expensive.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an economical double-sided surface grinding wheel having a long grinding wheel life.

[0006]

The gist of the present invention for attaining the above object is to cut a material on both sides of a work material by passing the work material between a pair of grinding planes opposed to each other. In the double-sided surface grinding grindstone to be processed, the proportion of the microcrystalline sintered alumina-based abrasive particles contained in the abrasive particles on the grinding surface is increased to the outer peripheral position within the range of 10 to 70% by volume. is there.

[0007]

In this way, the ratio of the microcrystalline sintered alumina-based abrasive grains contained in the abrasive grains on the grinding plane of the double-sided surface grinding wheel is 10 to 70% by volume on the outer periphery. Since the height is increased toward the side position, wear is suppressed toward the outer peripheral portion of the grinding plane, so that the life of the grindstone becomes longer and the dressing interval becomes longer. Further, compared with the case where microcrystalline sintered alumina abrasive grains are mixed at the same ratio over the entire grinding plane of the double-sided surface grinding wheel,
Since the mixing ratio is reduced toward the inner peripheral side, the double-sided surface grinding wheel can be manufactured relatively inexpensively. If the proportion of the microcrystalline sintered alumina-based abrasive grains contained in the abrasive grains on the grinding surface of the double-sided surface grinding wheel falls below 10% by volume, it becomes difficult to obtain a substantially effective effect, and 70% by volume is not obtained. When it exceeds, the effect of mixing the microcrystalline sintered alumina abrasive grains is saturated and the cost becomes high.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view of a double-sided surface grinding wheel 10.

In the figure, a double-sided surface grindstone 10 is a discoid resinoid grindstone in which abrasive grains are bonded by an epoxy resin, which is a thermosetting resin that functions as a resin bond, and has a grinding plane 12 located on one side. It is fixed to the base 14 by a plurality of mounting bolts (not shown). This pedestal 14 is fixed to a rotary shaft (not shown), and a work material is passed along a guide rail between a pair of grinding planes 12 opposed to each other so that both surfaces of the work material are ground. It has become.

The double-sided surface grinding wheel 10 is, for example, 5
It is formed to have a diameter of about 85 mmφ and a thickness dimension of about 75 mm, and the work material is, for example, an inner or outer ring of a bearing, and is formed to have a diameter of about 40 to 70 mmφ and a thickness dimension of about 16 to 24 mm. ing.

The double-sided surface grinding wheel 10 has an outer peripheral portion 16 having a high peripheral speed and a large grinding load, and an inner peripheral portion 18 having a relatively small grinding load because it is located inside the outer peripheral portion 16.
It has and. The outer peripheral portion 16 has, for example, a composition of 41% by volume of abrasive grains, 35% by volume of epoxy resin functioning as a resin bond, and the remaining volume of pores, and 70% of the volume of the abrasive grains has a submicron size. Microcrystalline sintered alumina-based abrasive grains in which fine-grained alumina particles having a certain size are densely bonded by sintering are used, and 30% is white alundum WA. Similarly, the inner peripheral portion 18 also has a composition in which 41% by volume of abrasive grains, 35% by volume of epoxy resin functioning as a resin bond, and the remaining volume is pores, but 100% of the volume of the abrasive grains. Is White Alundum WA.

The above-mentioned microcrystalline sintered alumina-based abrasive grains are disclosed, for example, in US Pat. No. 4,323,364 and US Pat. No. 43.
No. 14827, U.S. Pat. No. 4,744,802, etc., for example, an aqueous sol is produced from microcrystalline hydrated alumina and a mineral acid, and the aqueous sol contains a predetermined amount of zirconia or Spinel forming magnesia, etc. may be included, but with or without the addition of an effective amount of submicron α-alumina or α-ferric oxide that acts as a seed or nucleating agent during high temperature firing, and further sheet forming. Alternatively, after being extruded and then granulated by drying and crushing,
For example, it is manufactured by firing at about 1400 degrees. Such microcrystalline sintered alumina abrasive grains have high toughness, and the abrasive grain cutting edge is finely crushed to constantly create a new sharp cutting edge, so that excellent grinding performance can be obtained.

The double-sided surface grinding wheel 10 contains, for example, WA abrasive grains, liquid epoxy resin, and microcrystalline sintered alumina-based abrasive grains adjusted in a predetermined ratio for forming the outer peripheral portion 16 in the first kneading step. Kneading with a kneading machine, the second
In the kneading step, the WA abrasive grains and the liquid epoxy resin, which are adjusted at a predetermined ratio for forming the inner peripheral portion 18, are kneaded by using a kneader. In the first charging step, only the amount of the material prepared in the first kneading step for forming the outer peripheral portion 16 is charged into the molding die, and then in the second charging step, prepared in the second kneading step. Only the amount of the formed material for forming the inner peripheral portion 18 is charged in the molding die, and the material charged in the molding die is press-molded in a press-molding step and then aged. The double-sided surface grinding wheel 10 is manufactured by being hardened by being heated at a temperature of about 130 to 180 ° C. for a predetermined time in the process, and being finished in the finishing process.

Table 1 shows the results of experiments conducted by the inventors of the present invention on the following double-sided surface grinding wheels (A), (B), and (C) under the following grinding conditions. In addition, in Table 1, the life and dressing intervals are 100 for a double-sided surface grinding wheel (C).
It is shown by the value when.

Double-sided surface grinding wheel (A) outer peripheral portion and inner peripheral portion: Abrasive grains 41% by volume [70% by volume of the abrasive grains are # 46 microcrystalline sintered alumina abrasive grains, 30% by volume are # 46 White Alundum WA Abrasives] Binder (epoxy resin) 35% by volume Porosity 24% by volume ・ Double-sided surface grinding wheel (B) Outer periphery: Abrasive 41% by volume [70% by volume of abrasive #
46 microcrystalline sintered alumina abrasive grains, 30% by volume is # 4
White Alundum WA Abrasive Grains of 6] Binder (Epoxy Resin) 35% by Volume Porosity 24% by Volume Inner Circumference: Abrasive Grains 41% by Volume [100% by Volume of Abrasive Grains is # 46 White Alundum WA Abrasive Grains] Binder (epoxy resin) 35% by volume Porosity 24% by volume Double-sided surface grinding wheel (C): Outer and inner peripheral parts: Abrasive grains 41% by volume [100% by volume of abrasive grains # 46 White Alundum WA Abrasive] Binder (epoxy resin) 35% by volume Porosity 24% by volume

Grinding conditions Work material: SUJ-2 bearing material (40 mmφ x 16 mm
t) Feed rate: 5 m / min Grinding wheel peripheral speed: 1810 m / min Grinding fluid: emulsion

[0017]

[Table 1]

As is clear from Table 1, the double-sided surface grinding wheel (B) in which the abrasive grains in the outer peripheral portion 16 are mixed with the abrasive grains in a high ratio of 70% is a microcrystalline sintered stone. Since the grinding performance of the alumina-bonded abrasive grains is exhibited properly and the outer peripheral portion 16 is less consumed, the life is equal to or longer than that of the double-sided surface grinding wheel (A) in which the microcrystalline sintered alumina-based abrasive grains are evenly mixed. At the same time as the dressing interval is obtained, the inner peripheral portion 18 is inexpensive because the microcrystalline sintered alumina abrasive grains are not contained. In addition, the above double-sided surface grinding wheel
(B) has a life and dressing interval of about 2.5 times that of the double-sided surface grinding wheel (C) in which microcrystalline sintered alumina abrasive grains are not mixed in the outer peripheral portion.

FIG. 2 is a perspective view showing a double-sided surface grinding wheel 30 according to another embodiment of the present invention. In the figure, a double-sided surface grindstone 30 is a discoid resinoid grindstone in which abrasive grains are bonded by a phenol resin, which is a thermosetting resin that functions as a resin bond, and is provided with a grinding plane 32 located on one surface. It is fixed to 34 by a plurality of mounting bolts (not shown). The double-sided surface grinding wheel 30 is also manufactured by the same process as the double-sided surface grinding wheel 10.

The double-sided surface grinding wheel 30 is, for example, 7
The work material is a piston ring, for example, and has a diameter of about 50 to 120 mmφ and a thickness of about 1 to 4 mm.

The double-sided surface grinding wheel 30 has an outer peripheral portion 36 having a high peripheral speed and a large grinding load, and an intermediate portion 38 having a relatively small grinding load because it is located inside the outer peripheral portion 36.
And an inner peripheral portion 40 having the smallest grinding load because it is located inside the intermediate portion 38. The outer peripheral portion 36
Is a composition in which, for example, 44% by volume of abrasive grains, 19% by volume of phenol resin functioning as a resin bond, and the remaining volume consists of pores, and 50% of the volume of the abrasive grains is a fine particle having a submicron size. The crystalline alumina particles are microcrystalline sintered aluminous abrasive grains that are densely bonded by sintering, and the remaining 50% is green carborundum GC. The intermediate portion 38 has a composition of 44% by volume of abrasive grains, 13.2% by volume of phenol resin functioning as a resin bond, and the remaining volume consisting of pores, and 30% of the volume of the abrasive grains is small. Crystalline sintered alumina abrasive grains,
The remaining 70% by volume is Green Carborundum GC. The inner peripheral portion 40 has a composition in which the abrasive grains are 44% by volume, the phenol resin functioning as a resin bond is 6.6% by volume, and the remaining volume is pores. It is Green Carborundum GC.

Table 2 shows the results of experiments conducted by the present inventors on the following double-sided surface grinding wheels (D), (E) and (F) under the grinding conditions shown below. In Table 1, the life and dressing intervals are 100 for a double-sided surface grinding wheel (F).
It is shown by the value when.

Double-sided surface grinding wheel (D) Outer peripheral portion, intermediate portion, and inner peripheral portion: Abrasive grains 44% by volume [50% by volume of the abrasive grains are microcrystalline sintered alumina abrasive grains of # 60, 50 Green carborundum GC abrasive grain with volume% of # 60] Binder (phenolic resin) 19 volume% Pore 37 volume% ・ Double-sided surface grinding wheel (E) Outer periphery: Abrasive grain 44 volume% [50 volume% of the abrasive grain But#
60 microcrystalline sintered alumina abrasive grains, 50% by volume of # 6
0 Green Carborundum GC Abrasive Grain] Binder (phenol resin) 19% by volume Porosity 37% by volume Intermediate part: Abrasive grain 44% by volume [30% by volume of abrasive grain is #
60 microcrystalline sintered alumina abrasive grains, 70% by volume of # 6
0 Green Carborundum GC Abrasive] Binder (phenol resin) 13% by volume Porosity 43% by volume Inner circumference: Abrasive 44% (100% by volume of # 60 green carborundum GC abrasive) Binder (epoxy resin) 7% by volume Porosity 49% by volume Double-sided surface grinding wheel (F): Outer peripheral portion, middle portion, and inner peripheral portion: Abrasive grains 44% by volume [30% by volume of abrasive grains # 60 Microcrystalline Sintered Alumina Abrasive Grains, 70% by Volume of # 60 Green Carborundum GC Abrasive Grain] Binder (phenolic resin) 19% by volume Porosity 37% by volume

Grinding conditions Work material: FC20 Piston ring (90 mmφ) Feed rate: 10 m / min Grinding wheel peripheral speed: 1800 m / min Grinding fluid: emulsion

[0025]

[Table 2]

As is clear from Table 2, the double-sided surface grinding wheel (E) in which the abrasive grains in the outer peripheral portion 36 are mixed with the abrasive grains in a high proportion of 50% is a microcrystalline sintered stone. Since the grinding performance of the alumina-bonded abrasive grains is optimally exhibited and the outer peripheral portion 36 is less consumed, the life is equal to or longer than that of a double-sided surface grinding wheel (D) in which microcrystalline sintered alumina-based abrasive grains are evenly mixed. At the same time that the dressing interval is obtained, the content of the microcrystalline sintered aluminous abrasive grains in the intermediate portion 38 is small and the inner peripheral portion 40 is not contained, so that the cost is low. In addition, the above double-sided surface grinding wheel (E) has a life and dressing that is about 2.5 times longer than that of the double-sided surface grinding wheel (F) in which microcrystalline sintered alumina-based abrasive grains are not mixed in the outer periphery at a high ratio. It becomes an interval.

As described above, according to the double-sided surface grinding wheels 10 and 30 of the present embodiment, the ratio of the microcrystalline sintered alumina-based abrasive grains contained in the abrasive grains on the grinding planes 12 and 32 is 10. Since the outer peripheral position of the grinding surface 12 and 32 is increased in the range of up to 70% by volume, wear is suppressed toward the outer peripheral portions of the grinding planes 12, 32, so that the life of the grindstone becomes longer and the dressing interval becomes longer. In addition, double-sided surface grinding wheel 10,
Compared to the case where the microcrystalline sintered alumina abrasive grains are mixed at the same ratio over the entire grinding planes 12 and 32 of 30, the mixing ratio is decreased toward the inner peripheral side. , 30 are manufactured relatively inexpensively. If the proportion of the microcrystalline sintered alumina-based abrasive grains contained in the abrasive grains on the grinding planes 12, 32 of the double-sided surface grinding wheels 10, 30 is less than 10% by volume, it is difficult to obtain a substantially effective effect. If it exceeds 70% by volume, the effect of mixing the microcrystalline sintered alumina abrasive grains is saturated and the cost becomes high.

In the double-sided surface grinding wheel 10 described above, the ratio of the microcrystalline sintered alumina-based abrasive particles to the abrasive particles is changed in two steps, and in the double-sided surface grinding wheel 30, it is changed in three steps. However, it can be changed in four or more steps.

The above description is merely an embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of drawings]

FIG. 1 is a perspective view showing a double-sided surface grinding wheel according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a double-sided surface grinding wheel according to another embodiment of the present invention.

[Explanation of symbols]

 10, 30: Double-sided surface grinding wheel 12: Grinding surface 16, 36: Outer peripheral part 38: Intermediate part 18, 40: Inner peripheral part

Claims (1)

[Claims] 1. A double-sided surface grinding grindstone for cutting both surfaces of a work material by passing the work material between a pair of opposing grinding surfaces, wherein the fine grains contained in the abrasive grains on the grinding surface. A double-sided surface grinding wheel, characterized in that the proportion of the crystalline sintered alumina-based abrasive grains is increased to the outer peripheral side position within the range of 10 to 70% by volume.