JP4318678B2 - Grinding wheel - Google Patents

Description

  The present invention relates to a polishing grindstone mainly used for polishing a spherical surface of a spherical work material such as a steel ball or a ceramic ball.

FIG. 9 shows the appearance of a polishing grindstone used to polish a spherical surface of a spherical work material such as a steel ball or a ceramic ball.
In FIG. 9A, a polishing grindstone 51 is formed by forming an abrasive grain layer 53 on one surface of a disc-shaped base metal 52 formed of iron or the like, and on the opposite surface thereof. An inlay 54 for attaching the rotating shaft is provided.

  Details of the polishing surface of the polishing wheel 51 are shown in FIGS. FIG. 9B shows an abrasive layer formed flat, and an abrasive layer 53 having a flat polished surface is formed on the outer peripheral side of the base metal 52. In this type of grinding wheel, the work material is polished as shown in FIG. 9 (d), but a groove formed by the contact between the sphere as the work material and the abrasive grain layer 53 is formed in the abrasive grain layer 53. There is a drawback that it takes a certain amount of leveling time to form on the surface.

FIG. 9C shows an abrasive layer formed in a groove shape, and an abrasive layer 53 having a polished surface provided with a groove 55 is formed on the outer peripheral side of the base metal 52. With this type of grinding wheel, the work material is polished as shown in FIG. 9 (e). Since the groove 55 is formed in advance, it takes less time to cut, but the groove 55 is formed. As a result, the thickness of the abrasive grain layer 53 at the position where the groove 55 is formed is reduced, and the life of the grinding wheel is reduced.
A polishing apparatus in which the thickness of the abrasive grain layer is not reduced in consideration of the shape of the abrasive grain layer is described in Patent Document 1.

Japanese Patent Laid-Open No. 3-136664

However, when the abrasive grain layer described in Patent Document 1 is formed, it is possible to prevent the thickness of the abrasive grain layer from being reduced. However, when the abrasive grain layer is used up, the exposed iron base metal is spherically cut. The material comes into contact and damages the work material, which tends to deteriorate the roundness accuracy. This is because the shape of the groove collapses due to the fact that the sphere, which is the work material, is repeatedly subjected to compressive stress on the iron base metal, causing fatigue fracture and peeling near the groove surface. Therefore, after all, it has to be discarded before the abrasive grain layer is used up, and the abrasive grain layer cannot be used effectively to the end.
The present invention has been made to solve the above problems, and even when the abrasive grain layer is completely used, the occurrence of scratches on the spherical work material and the deterioration of the roundness accuracy can be prevented. An object of the present invention is to provide a polishing wheel that is possible and has an excellent life.

  In order to solve the above problems, the polishing wheel of the present invention is a polishing wheel in which an abrasive layer is formed on the outer peripheral side of a disk-shaped base metal, and contains a solid lubricant on the lower side of the abrasive layer. A powder sintered copper alloy layer is formed, a first groove is provided on the surface of the abrasive layer, and a copper alloy layer by powder sintering containing a solid lubricant according to the first groove. The second groove is provided, the second groove is also provided with an abrasive layer, the radius of curvature of the first groove is R1, and the height difference between the surface of the abrasive layer and the lowest part of the first groove Is H1, the radius of curvature of the second groove provided in the copper alloy layer is R2, the linear boundary between the abrasive grain layer and the copper alloy layer, and the height of the lowest part of the second groove H1 is equal to or more than 1/4 times and not more than 3/4 times R1, and H2 is not less than 1/4 times and not more than 3/4 times R2.

The first groove provided on the surface of the abrasive layer not only shortens the leveling time,
By providing the second groove in accordance with the shape of the first groove provided on the surface of the abrasive grain layer on the powder sintered copper alloy layer containing the solid lubricant, the thickness of the abrasive grain layer is Since it becomes substantially the same over the entire area of the abrasive grain layer, there is no reduction in the cost of use due to grooving and the life is improved. In addition, a copper alloy layer formed by powder sintering containing a solid lubricant prevents the spherical work material from being scratched and the roundness accuracy from deteriorating even when the abrasive layer is used up. can do.

  When H1 is less than 1/4 of R1, the depth of the groove is too shallow, and the sphericity and surface roughness of the work material after machining are reduced. On the other hand, if H1 exceeds 3/4 of R1, the rotating whetstone and the fixed whetstone that are used facing each other with the work material interposed therebetween are likely to interfere with each other, which is not preferable. Further, when H1 is in the above range, in order to make the thickness of the abrasive grain layer substantially the same over the entire area of the abrasive grain layer, H2 is set to 1/4 times or more and 3/4 times or less of R2. It is preferable. When H2 is less than 1/4 of R2, the thickness of the abrasive layer is reduced and the life is shortened. On the other hand, if H2 exceeds 3/4 times R2, it is not preferable because an extra usage fee that is not used for processing can be made.

In the present invention, the copper alloy layer is made of 2.5% by volume or more and 10.0% by volume of molybdenum disulfide powder having an average particle size of 5 μm or less to a copper alloy powder-sintered mainly containing Cu—Sn—Ag. It is characterized by having a composition uniformly dispersed at a ratio of not more than%.
Molybdenum disulfide powder acts as an extreme pressure additive, and reduces the frictional resistance with a spherical work material by uniformly dispersing it in a powder sintered copper alloy. Further, by molding by the powder sintering method, the molybdenum disulfide powder exists between the particles of the metal powder, and has an effect of reducing the bonding force between the particles. As a result, even when subjected to repeated compressive stress of the sphere that is the work material, wear does not occur and fatigue failure does not occur.
When the content of the molybdenum disulfide powder is less than 2.5%, the lubrication action and the wear promoting action are lowered, and the occurrence of scratches on the spherical work material and the roundness accuracy are deteriorated. On the other hand, if it exceeds 10.0% by volume, the bonding force with the abrasive grain layer or the base metal is lowered and may be peeled off.

In the present invention, the radius of curvature R2 of the second groove is 1.05 times or more the radius of curvature R1 of the first groove.
When R2 is less than 1.05 times R1, when R2 is small when the abrasive grain layer is worn and its thickness is reduced, a portion that is not used for polishing is generated and the life is shortened. Therefore, it is preferable that the curvature radius R2 of the second groove is 1.05 times or more the curvature radius R1 of the first groove.

  According to the present invention, it is possible to realize a polishing grindstone having a long service life that can shorten the leveling time and can use the abrasive grain layer to the end.

Below, the grinding stone of the present invention is explained based on the embodiment.
As shown in FIG. 1, the basic structure of a polishing grindstone according to an embodiment of the present invention is such that an abrasive grain layer 3 is formed on one surface of a disk-shaped base metal 2 made of iron or the like. And an inlay 4 for attaching the rotating shaft is provided on the opposite surface.
Details of the formation of the abrasive grain layer 3 of the polishing grindstone will be described with reference to FIG.

  FIG. 2 is a cross-sectional view taken along the line AA of the polishing grindstone 1. An abrasive grain layer 3 is provided on the outer peripheral side of the base metal 2, and a groove 5 is provided on the surface of the abrasive grain layer 3. Corresponding to the groove 5, a groove 6 is also provided in a copper alloy layer (hereinafter referred to as "copper alloy layer") 2a by powder sintering containing a solid lubricant, and the thickness of the abrasive grain layer 3 is determined by the abrasive grain. It is substantially the same over the entire area of the layer 3.

FIG. 3 shows details of the groove shape.
In FIG. 3A, the radius of curvature of the groove 5 provided in the abrasive grain layer 3 is R1, and the height difference between the surface of the abrasive grain layer 3 and the lowest part of the groove 5 is H1. Further, the radius of curvature of the groove 6 provided in the copper alloy layer 2a is R2, and the height difference between the linear boundary between the abrasive grain layer 3 and the copper alloy layer 2a and the lowermost portion of the groove 6 is H2. .

FIGS. 3B and 3C show polishing conditions when the magnitude relationship between H1 and R1 is changed.
FIG. 3B shows a case where H1 is less than 1/4 of R1, and the arc of the abrasive layer 3 in contact with the work material is small, and the groove 5 formed in the abrasive layer 3 is shallow. In addition, the roundness and surface roughness of the work material decrease. FIG. 3 (c) shows the case where H1 exceeds 3/4 times R1, and the abrasive grind layer 3 of the rotating grindstone and the fixed grindstone used facing each other across the spherical work material approaches. Thus, the rotating grindstone and the fixed grindstone easily interfere with each other.

FIGS. 3D and 3E show the polishing conditions when the magnitude relationship between H2 and R2 is changed.
FIG. 3 (d) shows the case where H2 is less than 1/4 times R2, and the thickness of the abrasive grain layer 3 is reduced and the life is shortened. FIG. 3 (e) shows a case where H2 exceeds 3/4 times R2, and an extra usage fee 7 that is not used for processing is formed.
From the above, in order to improve the machining efficiency and machining accuracy, H1 is ¼ times to ¾ times R1, and H2 is ¼ times to ¾ times R2. It is preferable.

  The machining allowance of the sphere to be polished is approximately within 1.05 times R1, and R2 is preferably set to be larger than 1.05 times R1. When R2 is less than 1.05 times R1, when the abrasive layer 3 wears and decreases, the copper alloy layer 2a is exposed, or the groove R1 of the abrasive layer 3 and the groove R2 of the copper alloy layer Since the copper alloy layer 2a is exposed by a slight pitch shift, it is not preferable. The copper alloy layer 2a prevents damage to the spherical work material and deterioration of the roundness accuracy, but it is not preferable that the copper alloy layer 2a is exposed even though the abrasive grain layer 3 remains. .

The exposure of the copper alloy layer 2a will be described with reference to FIGS. 3 (f) and 3 (g).
FIG. 3 (f) shows a case where R2 is set to 1.05 times or more of R1, and in this case, since R2 is large, the abrasive layer 3 is worn and the grinding is performed as shown by a broken line. Even if the thickness of the grain layer 3 decreases, it can be used effectively until the abrasive grain layer is used up.
On the other hand, FIG. 3 (g) shows a case where R2 is less than 1.05 times R1, and since R2 is small, the abrasive grain layer 3 is worn and its thickness is reduced. In the region 8 indicated by hatching, the copper alloy layer 2a is partially exposed despite the use fee still remaining.

Specific production examples and test examples are shown below.
Tables 1 and 2 show the test conditions.

Work material and machining conditions

Test wheel

  The test results are shown in FIGS. 4 to 6, the height difference H1 between the surface of the abrasive grain layer 3 and the lowermost part of the groove 5 is changed, and the abrasive grain layer 3 and the copper alloy layer 2a are changed accordingly. The difference in height H2 between the straight boundary and the lowermost portion of the groove 6 is similarly changed.

  FIG. 4 shows the leveling time when the height difference between the surface of the abrasive grain layer 3 and the lowermost part of the groove 5 is changed, and when the height difference is less than 1/4 times R1. Although it is necessary to take a longer run-in time, the run-in time can be shortened when the difference in height is 1/4 times or more of R1.

  FIG. 5 shows the sphericity of the work material when the difference in height between the surface of the abrasive grain layer 3 and the lowest part of the groove 5 is changed, and FIG. 6 shows the surface roughness of the work material. Indicates. In any case, a good value is shown when the difference in height is 1/4 times or more of R1. In addition, both the sphericity and the surface treatment indicate that the accuracy is better as the numerical value is lower.

  In the test results shown in FIGS. 4 to 6, good results are shown if the difference in height between the surface of the abrasive grain layer 3 and the lowermost portion of the groove 5 is 1/4 times or more of R1, If the difference in height exceeds 3/4 times R1, the rotating whetstone and the fixed whetstone that are used facing each other with the work material interposed therebetween are likely to interfere with each other, which is not preferable. Therefore, the height difference H1 between the surface of the abrasive grain layer 3 and the lowermost part of the groove 5 is preferably not less than 1/4 times and not more than 3/4 times R1, and accordingly, the abrasive grain layer 3 In order to ensure a sufficient thickness, the height difference H2 between the linear boundary between the abrasive grain layer 3 and the copper alloy layer 2a and the lowermost portion of the groove 6 is equal to or more than 1/4 times and 3/4 times that of R2. The following is recommended.

FIG. 7 shows the iron base metal when the test was performed by changing the content of molybdenum disulfide in the copper alloy layer 2a from 0 to 20% by volume with the copper alloy layer 2a completely exposed. Changes in bonding strength are shown. The bonding strength with the iron base metal is 100% when the molybdenum disulfide content is 0%. When the addition amount of molybdenum disulfide was 10% or more, the bonding strength with the iron base metal began to rapidly decrease, and when the addition amount was 20%, it decreased to 30%. This indicates that this is an adverse effect of excessive addition of molybdenum disulfide.
Further, when the surface condition of the work material was confirmed, the work material was scratched when the addition amount was 2.5% or less. At this time, burrs shown in FIG. 8 were observed in the groove H2 of the copper alloy layer. This is because the amount of molybdenum disulfide added is small and difficult to wear, so the groove undergoes plastic deformation under repeated compression stress of the work material, and scratches on the work material are caused by burrs formed by this plastic deformation. It seems that the material was damaged and scratched.
Accordingly, the molybdenum disulfide content of the copper alloy layer is preferably 2.5% to 10%.

  INDUSTRIAL APPLICABILITY The present invention can be used as a long-life polishing grindstone that can shorten the leveling time and can use the abrasive grain layer to the end.

It is a figure which shows the basic structure of a grindstone. It is sectional drawing of a grinding wheel. It is a figure which shows the detail of the shape of a groove | channel. It is a figure which shows the leveling time when changing the difference of the height of the surface of an abrasive grain layer, and the lowest part of a groove | channel. It is a figure which shows the sphericity of a to-be-cut material when the difference of the height of the surface of an abrasive grain layer and the lowest part of a groove | channel is changed. It is a figure which shows the surface treatment of a workpiece when changing the height difference of the surface of an abrasive grain layer, and the lowest part of a groove | channel. Fig. 4 shows the change in bonding strength with an iron base metal when the test was performed by changing the content of molybdenum disulfide in the copper alloy layer from 0 to 20% by volume with the copper alloy layer completely exposed. FIG. It is a figure which shows generation | occurrence | production of the burr | flash in a copper alloy layer. It is a figure which shows the conventional grinding wheel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Grinding wheel 2 Base metal 2a Copper alloy layer 3 Abrasive grain layer 4 Inlay 5 Groove 6 Groove 7 Excess use cost 8 area | region

Claims (3)

  In a polishing wheel in which an abrasive layer is formed on the outer peripheral side of a disk-shaped base metal, a copper alloy layer containing a solid lubricant is formed on the lower side of the abrasive layer, and the abrasive layer A first groove is provided on the surface of the copper alloy, a second groove is provided in a layer of a copper alloy by powder sintering containing a solid lubricant in accordance with the first groove, and abrasive grains are also provided in the second groove. The first groove has a radius of curvature R1, and the difference in height between the surface of the abrasive layer and the lowermost portion of the first groove is H1, and a second layer provided in the copper alloy layer. When the radius of curvature of the groove is R2, and the height difference between the linear boundary between the abrasive layer and the copper alloy layer and the bottom of the second groove is H2, H1 is 1/4 of R1. A polishing grindstone characterized in that it is not less than 2 times and not more than 3/4 times, and H2 is not less than 1/4 times and not more than 3/4 times of R2.   The copper alloy layer by powder sintering containing a solid lubricant was prepared by adding 2.5 volume of molybdenum disulfide powder having an average particle size of 5 μm or less to a copper alloy powder sintered with Cu—Sn—Ag as a main component. The polishing grindstone according to claim 1, which is uniformly dispersed at a rate of not less than% and not more than 10.0% by volume.   The grinding wheel according to claim 1 or 2, wherein a curvature radius R2 of the second groove is 1.05 times or more of a curvature radius R1 of the first groove.

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