JPH0366570A - Grindstone for grinding curved face - Google Patents

Abstract

PURPOSE:To make a grinding face abutted on the face to be ground with an almost uniform pressure over the whole face, to prevent the excessive biting of a partial abrasive grain and to improve the surface roughness with the prevention of a streak formation, by supporting a thin electrocast abrasive grain layer having flexibility by an elastic layer. CONSTITUTION:An elastic layer 11 is fixed onto a grindstone base body 10, a curved face 11A corresponding to the grinding face of the material to be ground is formed by this elestic layer 11 and also an electrocast abrasive grain layer 12 formed in a thin plate shape by dispersing super abrasive grains into a metal plating phase is fixed by its sticking to this curved face 11A. Consequently, when this electrocast abrasive grain layer 12 is pressed to the face to be ground, the grinding face 12A thereof is deformed along the shape of the face to be ground, abutted on the face to be ground with the pressure almost uniform over the whole face and the excess local abutting pressure is difficult to be caused. The excessive biting of a partial abrasive grain due to the excess abutting pressure is prevented, the streak generation is prevented and the surface roughness can be improved.

Description

Detailed Description of the Invention "Industrial Field 111" The present invention relates to a curved surface grinding wheel used for precision finishing of a curved surface, such as a honing wheel or a superfinishing wheel. This invention relates to improvements to extend service life and improve conformability to the workpiece surface.

"Prior Art" As representative examples of this type of grindstone for curved surface grinding, a superfinishing whetstone and a honing whetstone will be cited and explained.

In superfinish grinding, as shown in Fig. 11, the workpiece W is rotated around its axis, and the superfinishing grindstone 1 is pressed against the outer circumferential surface of the workpiece W with a constant pressure, while the grindstone l is rotated in the axial direction with an amplitude of several square meters. ·hundreds~
This method creates a mirror finish by vibrating at a frequency of several thousand cycles/minute.

Conventionally, this type of superfinishing grindstone uses GC-based abrasive grains for cast iron or non-ferrous metals, WA-based abrasive grains for LI4, and diamond abrasive grains for cemented carbide. , chromium oxide abrasive grains were used for soft metals. The abrasive grain size is usually #600fu, or in the case of two-step finishing, it is #300-400 for roughing and #60 for finishing.
0 to 1500 is normal. Vitrified bond is mainly used as the bonding agent, but rubber bond and resinoid bond may also be used for soft metals. Furthermore, in the case of diamond abrasive grains, metal bond or resinoid bond is generally used.

Note that the illustrated example is an example of cylindrical outer surface finishing, and various other types of curved surface finishing such as cylindrical inner surface finishing are also performed.

Next, FIG. 12 shows internal honing as an example of the honing process, where 2 is a honing head and 3 is a plurality of rod-shaped grindstones supported by the head 2.

And by the pressing mechanism built into the honing head 2,
Each grindstone 3 is brought into surface contact with the inner surface of the cylinder W to be ground, and the honing head 2 is rotated and reciprocated in the axial direction to perform finish grinding.

The abrasive grains and bonding layer constituting this type of honing whetstone are the same as those for superfinishing, but the grain size of the abrasive grains is slightly coarser than that for superfinishing, and approximately #120 to #600 is generally used.

``Problem to be solved by the invention'' By the way, in the case of the above-mentioned superfinishing and honing, the abrasive grain diameter is smaller than in other grinding methods, and the direction of the force applied to the abrasive grains changes drastically during grinding. Therefore, there was a problem that the abrasive grains fell off quickly and the life of the whetstone was short.

Therefore, in order to extend the life of the whetstone, diamond or C
It is conceivable to use an electrodeposited grindstone in which superabrasive grains such as BN are fixed to the surface of a grindstone base by a metal plating phase. This is because, if electrodeposited, the holding power of the superabrasive grains is significantly improved compared to a metal bonded grindstone, and the dropout of the abrasive grains is significantly reduced.

However, when the inventors actually created such an electrodeposited grindstone and conducted a grinding test, it was found that although the number of abrasive particles falling off was reduced, the shape of the grinding surface did not adapt to the shape of the workpiece surface as it was being ground. The problem was that the abrasive grains in those areas were deeply embedded in the workpiece surface due to excessive local contact pressure, resulting in the formation of scratches. For this reason,
It takes a long time to run-in until the shape of the grinding surface matches the shape of the workpiece surface, and during this time a large number of defective products that do not meet the specifications are produced, resulting in a reduction in yield.

"Means for Solving the Problems" The present invention has been made to solve the above problems, and includes fixing an elastic layer on a grinding wheel base, and forming a curved surface corresponding to the grinding surface of the workpiece with this elastic layer. In addition, it is characterized in that an electroformed abrasive grain layer formed into a thin plate by dispersing superabrasive grains in a metal plating phase is attached and fixed to the curved surface.

[Function] According to this grindstone for curved surface grinding, the flexible thin electroformed abrasive grain layer is supported by the elastic layer, so when the electroformed abrasive grain layer is pressed against the workpiece surface, the grinding surface deforms along the shape of the surface to be cut, and the grinding surface contacts the surface with substantially uniform pressure over the entire surface, making it difficult for local excessive contact pressure to occur.

Therefore, it is possible to prevent some of the abrasive grains from digging into too much due to excessive contact pressure, prevent the generation of streaks, and improve the surface roughness. Since a grain layer is used, there is less chance of superabrasive grains falling off, and the life of the grinding wheel can be significantly extended. In addition, since it adapts to the work material from the beginning of grinding, the break-in time is short, and the product yield during that time can be improved.

Embodiment FIG. 1 is a front view showing a superfinishing grindstone as a first embodiment of the curved surface grinding wheel according to the present invention.

Reference numeral 10 denotes a grindstone base body, and its - face 10A is formed into a curved surface corresponding to the grinding surface of the workpiece, and an elastic layer II of a constant thickness is fixed to this curved surface 10A by adhesive or the like. The material of the grinding wheel base IO may be any conventionally used material such as metal, and its shape is changed as appropriate to correspond to the superfinishing machine.

Elastic layer! l refers to elastic materials such as synthetic rubber such as urethane rubber, and various thermoplastic or thermosetting elastomers such as polyester and acrylic, which are not affected by light oil, kerosene, etc. commonly used as grinding fluid for super finishing. Material is selected. The elastic layer 11 may have either a porous structure or a non-porous structure, but its thickness and elastic modulus should be set so that the electroformed abrasive layer 12 (described later) can sufficiently conform to the curved surface of the workpiece, and The settings should be made so that the electroformed abrasive layer 12 does not wobble and cause uneven grinding even during finishing vibration.

Specifically, when the thickness of the elastic layer 11 is constant, the bulk modulus is 2000 to 6000, 9/■2, and the thickness is 0.5 to 5.
It is preferable that it is about mm1. stomach. Bulk modulus is 10
If the thickness is less than 0 or greater than 5 cm, the electroformed abrasive layer 12 may wobble during grinding, leading to a decrease in the accuracy of the finished surface. On the other hand, if the bulk modulus is greater than 6000 or the thickness is less than 0.5 cm, sufficient conformability cannot be obtained.

The curved surface 11A of the elastic layer 11 is made approximately equal to the curvature of the surface to be cut, and this curved surface has an electroformed abrasive layer 12 formed by dispersing superabrasive grains such as diamond or CBN in a metal plating phase such as Ni or Co. is fixed.

This electroformed abrasive grain layer I2 has a constant thickness over the entire surface, and it is desirable that the thickness is about 30 to 300 μl. 3
If it is thicker than 00 μl, the rigidity is too high to improve conformability, and if it is thinner than 30 μl, the service life will be short and impractical.

The grain size of the superabrasive grains is preferably #400 to #1000, and #415
When abrasive grains of less than 0.00 are mixed, the density of the grinding blades decreases, the contact pressure of each grinding blade increases, and the surface roughness worsens.

Furthermore, if abrasive grains larger than #400 are mixed in, the amount of protrusion caused by these grains increases, and the roughness becomes worse.

The content of superabrasive grains is preferably 20 to 40 vol%. If it is less than 20vo1%, the exposed density of abrasive grains decreases,
The pressure on each cutting edge increases and the depth of cut deepens.
Reduces surface roughness. Moreover, if it is larger than 4°vo1%, the sharpness decreases due to clogging, etc.

According to the superfinishing whetstone having the above configuration, since the flexible thin electroformed abrasive layer I2 is supported by the elastic layer II, when the electroformed abrasive layer 12 is pressed against the surface to be cut,
The grinding surface 12A deforms along the shape of the surface to be cut, and the grinding surface 12A contacts the surface with substantially constant pressure over the entire surface, making it difficult for local excessive contact pressure to occur. Therefore, it is possible to prevent some of the abrasive grains from biting in too much due to excessive contact pressure, prevent the formation of striations, and improve the surface roughness.

In addition, since the electrodeposited abrasive layer 12 in which superabrasive grains are firmly supported by a metal plating phase is used, there is less chance of superabrasive grains falling off, significantly extending the life of the grinding wheel compared to conventional superfinishing grindstones. can. In addition, since it adapts to the work material from the beginning of grinding, the break-in time can be shortened, and the product yield during that time can also be improved.

Furthermore, the electroformed abrasive grain layer 12 requires less expensive superabrasive grains than grinding wheels using other binders.
In addition to reducing manufacturing costs, the grindstone as a whole can be made lighter, so it also has the advantage that the driving force can be reduced accordingly.

In the above embodiment, the thickness of the elastic layer 11 was constant over the entire surface, but as shown in FIG. The electroformed abrasive layer 12 may be fixed through the concave elastic layer 11. In this case, the contact pressure on the workpiece surface is the abrasive layer!
2, it is slightly higher in the center and slightly lower in the periphery, but good conformability is maintained.

Further, as shown in FIG. 3, the curvature of the elastic layer mounting surface 10A of the grinding wheel base 10 is made larger than the surface to be cut of the workpiece material, and the electroformed abrasive grain layer 12 is inserted through the convex elastic layer 11 here. may be fixed. In this example, compared to the one in FIG.
The contact pressure at the central portion of 2 is relatively small.

Note that a configuration in which the grinding liquid is supplied to the grinding surface through the elastic layer and the electroformed abrasive layer is also possible. For example, in the example shown in FIG. 4, a liquid supply hole 13 and a liquid supply groove 14 are formed in the grinding wheel base 1o, and a through hole 15 communicating with the liquid supply groove is formed in the elastic layer 11 and the electroformed abrasive grain layer 12. ing.

In order to form the through holes 15 in the electroformed abrasive grain layer 12, it is preferable to use a laser beam or to perform pre-punching on the ground surface side. When a laser beam is used, the periphery of the through hole 15 is melted and becomes chamfered as shown in FIG. Further, according to the punching process, the ground surface is chamfered on the +2A side as shown in FIG. 6, and there is no risk of forming streaks on the surface to be cut.

Furthermore, as shown in FIG. 7, it is also possible to actively change the curvature of the electroformed abrasive grain layer 12.

A flexible support plate 17 made of metal or wood and bent to a constant curvature is fixed to the center of the curved surface of the whetstone base 16, and bearings are provided at both ends of the support plate 17.・
A rod 19 is rotatably connected via 18.

Male screws are formed at the tips of these rods 19, and one end of a nut 20 is screwed into each of the rods 19.

Further, at the other end of each nut 20, a rod 2 is rotatably connected to a bearing portion 21 formed on the side surface of the grindstone base body 16.
When the male threads at the ends of the two nuts 20 are screwed together and each nut 20 is rotated, the curvature of the support plate 17 can be changed within a predetermined range. Further, the electroformed abrasive layer 12 is fixed to the curved surface 17A of the support plate 17 via an elastic layer it of a constant thickness. These may be the same as above.

According to this example, by adjusting the nut 20, the grinding surface 12
Since it is easy to adapt the curvature of A to the surface to be cut, the elastic layer l! This has the advantage of further improving the familiarity.

Next, an example in which the present invention is applied to a honing stone will be described. Figure 8 shows an example of a grindstone for internal honing.
0 is a grindstone base body, 31 is an elastic layer of constant thickness, and 32 is an electroformed abrasive grain layer. The materials of each part may be the same as in the case of super finishing described above.

In this type of honing stone, when the thickness of the elastic layer 31 is constant, its bulk modulus is 2000 to 6000,
The thickness is preferably about 0.5 to 511 mm. bulk modulus is 5
If the thickness is less than 0.00 or the thickness is greater than 5.00, the electroformed low grain layer 32 may wobble. On the other hand, the bulk modulus is 6
If the thickness is larger than 0.000 or smaller than 0.5 m, the effect of improving conformity will be insufficient.

Further, the thickness of the electroformed abrasive grain layer 32 is desirably about 30 to 300 μm. If it is thicker than 300 μl, the rigidity is too high and it is difficult to improve the conformability, and if it is thinner than 30 μl, the life is short and it is not practical. The particle size of the superabrasive grains used is #400~800
It is desirable that the surface roughness is outside this range, and the surface roughness will deteriorate. Furthermore, the content of super abrasive grains is 20 to 40 vol.
It is desirable that If it is less than 20vol%, the exposed density of the abrasive grains decreases and the surface roughness decreases. Also, 40vo1
If it is larger than %, clogging problems will occur.

The same effects as the superfinishing whetstone described above can also be obtained with the honing whetstone having the above configuration.

It is also possible to form the elastic layer 31 in a concave or convex shape as shown in FIG. 9, or to form a liquid supply path 35 for the grinding fluid as shown in FIG. 10. Furthermore, it is possible to form a large number of depressions in the electroformed abrasive grain layer 32 to improve chip discharge performance, and the present invention is applicable not only to internal honing but also to external honing.

Further, the present invention is not only applicable to honing wheels and superfinishing wheels, but also to ground-type grindstones for machining curved surfaces.

"Experiment example" Next, the effects of the present invention will be demonstrated by giving experimental examples.

As a workpiece material, a needle for needle bearing (outer diameter 6
A grinding test was conducted using a superfinishing grindstone to which the present invention was applied. Required surface roughness H
Wax is 0.1μ.

An elastic layer made of urethane rubber having a predetermined thickness is attached to the curved surface of a grinding wheel base with an adhesive of 50 mm x 5 mm and a radius of curvature of lyxtx. Five types of super-finishing grindstones were created by attaching an abrasive layer.

Next, superfinishing was performed using each of these grindstones under the following conditions.

Rotational speed of workpiece material + 50 Orpm Grinding wheel vibration frequency: 1000 cycles/min Grinding wheel amplitude:
1wy Grinding wheel contact pressure crab 1000g/c shoulder 2 As a result of determining each part of the grinding wheel, the average value of the obtained finished surface roughness (Hmax), and the grinding wheel life, the suitable conditions for the grinding wheel in this example are as follows. It turned out to be.

Elastic layer thickness: 20.5~3M shoulder, bulk elastic modulus of elastic layer + 2000~6000 Electroformed abrasive layer thickness: 50~lOOμ diamond abrasive grain size: #1OO~1500 low grain Content: 25-30vo1% If the thickness of the elastic layer is less than 0.5cm, sufficient elasticity will not be obtained, and if it is thicker than 3 shoes, the electroformed abrasive layer will wobble due to the vibration of superfinishing, and the position of the grinding surface will deteriorate. This resulted in an unstable problem. Further, if the electroformed abrasive grain layer was thicker than 100 μl, sufficient conformability could not be obtained, and if it was thinner than 50 μl, sufficient strength could not be obtained.

Furthermore, when the abrasive grain size and content were outside the above ranges, the surface roughness decreased.

"Effects of the Invention" As explained above, according to the curved surface grinding wheel according to the present invention, since the flexible thin electroformed abrasive grain layer is supported by the elastic layer, the electroformed abrasive grain layer is When pressed against the workpiece surface, the grinding surface deforms along the shape of the workpiece surface, and the grinding surface contacts the workpiece surface with almost uniform pressure over the entire surface, causing localized excessive contact pressure. Hateful. Therefore, it is possible to prevent some of the abrasive grains from biting in too much due to excessive contact pressure, prevent the formation of striations, and improve the surface roughness.

In addition, since we use an electrodeposited abrasive layer in which the superabrasive grains are firmly supported by metal plating beads, there is less chance of the superabrasive grains falling off, and the life of the grinding wheel can be significantly extended compared to conventional superfinishing wheels. Since the wax blends into the work material from the beginning of grinding, the break-in time is short, and the product yield during that time can also be improved.

Furthermore, since electroformed superabrasive grains require less diamond abrasive grains, they also have the advantage of lower manufacturing costs compared to conventional superfinishing rough abrasive wheels ζ using diamond.

[Brief explanation of drawings]

FIG. 1 is a front view showing a super-finishing grindstone as an embodiment of the curved surface grinding wheel according to the present invention, and FIG.
FIG. 3 is a front view of the third embodiment, and FIG. 4 is a partially cutaway view of the fourth embodiment. FIGS. 5 and 6 are cross-sectional views of through holes formed in the electroformed abrasive layer, and FIG. 7 is a front view of the fifth embodiment. Moreover, FIGS. 8 to 10 are front views showing sixth to eighth embodiments in which the present invention is applied to a honing stone. On the other hand, FIG. 11 is a perspective view showing an example of superfinish grinding, and FIG. 12 is a plan view showing an example of inner honing. 10... Grinding wheel base, IOA... Curved surface, 11... Elastic layer, 11A... Curved surface, 12... 1!1tif abrasive grain layer, 12A... Grinding surface, l 3, 14.15 ...Liquid supply path, 17...Support plate, 18-21...Curvature changing mechanism, 30...Wheelstone base, 31...Elastic layer, 32...
Electroformed abrasive grain layer, 33.34.35...liquid supply path. Figure 1

Claims (1)

[Claims] An elastic layer is fixed on the grinding wheel base, and this elastic layer forms a curved surface that corresponds to the grinding surface of the workpiece. Electroformed abrasive grains are formed into a thin plate by dispersing superabrasive grains in the metal plating phase. A grindstone for grinding a curved surface, characterized in that a layer is attached and fixed to the curved surface.