JP2002113655A - Lapping surface plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lapping surface plate, excellent in retaining free abrasive grains, for performing lapping precisely with reduced roughness on the surface by using a small quantity of free abrasive grains. SOLUTION: The lapping surface plate is for lapping the surface of a processed object by using free abrasive grains, and the lapping surface of the lapping surface plate is made of a sintered body including 20-70 wt.% of copper powder, 10-80 wt.% of bronze powder and 0-15 wt.% of tin powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a lapping plate. More specifically, the present invention relates to a lap surface plate which has excellent holding power for free abrasive grains, has a small surface roughness, and can perform highly accurate lapping using a small amount of free abrasive grains.

[0002]

2. Description of the Related Art A lapping method in which a polishing liquid containing free abrasive grains such as diamond abrasive grains is dispersed between a lapping plate and a workpiece to finish the surface of the workpiece smoothly and accurately. Since it is easy and has a high processing efficiency, it is widely used as a finish processing for ceramics, glass, steel and the like. However, since diamond abrasive grains used for lapping are expensive, attempts have been made to economically perform lapping by preventing loss of loose abrasive grains. For example, Japanese Unexamined Patent Publication No. Hei 3-60970 discloses a polishing platen used for polishing a difficult-to-grind material with high precision and efficiency using diamond abrasive grains. There has been proposed a polishing platen made of a curable resin and fine powder of copper or tin having an average particle size of 10 to 150 μm and having a continuous porosity having a porosity of 30 to 70% by volume. However, this polishing platen has a drawback that high surface accuracy cannot be obtained because the thermosetting resin itself is largely deformed. For this purpose, the amount of diamond abrasive used has been reduced,
Attempts have been made to develop a lap surface plate that can achieve high surface accuracy.
For example, Japanese Patent Application Laid-Open No. Hei 8-25213 discloses that a lapping plate of a lapping polishing apparatus that can obtain surface smoothness of a member to be polished and reduce a deteriorated layer at the same time as the surface of the member to be polished has high rigidity. A base material made of synthetic resin fixed to the backup member, a soft metal particle dispersed in the base material and plastically deformed by the pressing of free abrasive grains on the polishing plane to bury the free abrasive grains; And a pore-forming agent that is dispersed in a solid state to form a large number of independent pores that are opened in the polishing plane by being discharged into the polishing liquid at the polishing plane. But,
Even when fixed to a highly rigid backup member, the Young's modulus of the synthetic resin and the pore-forming agent is at least one order of magnitude lower than that of soft metals, so extremely high precision, such as steel balls used for rolling bearings in hard disk drives Cannot be used for lapping that requires Meehanite cast iron is also used as a lap surface plate. The roughness also tends to be rough. For this reason, the entire lapping plate is made of highly rigid metal, and the amount of free abrasive particles used by piercing the surface of the lapping plate is small, the surface roughness is fine, and the precision ultra-precision lapping is performed. There has been a demand for a lap surface plate capable of performing processing.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a lapping plate which is excellent in holding force of loose abrasives, has a small surface roughness, and can perform high-precision lapping using a small amount of loose abrasives. It was made for the purpose of providing.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result,
By using a sintered body containing 20 to 70% by weight of copper powder, 10 to 80% by weight of bronze powder, and 0 to 15% by weight of tin powder, free abrasive grains can appropriately dig into the surface of the platen to effect lapping. The present invention has been found to be a lap surface plate which acts in a large manner and has a large rigidity and is less deformed by pressure during lapping. Based on this finding, the present invention has been completed.
That is, the present invention relates to (1) a lapping plate for polishing, which laps the surface of a workpiece using free abrasive grains,
The surface of the platen is 20-70% by weight of copper powder, 10% bronze powder
A lapping plate comprising a sintered body containing 80 to 80% by weight and 0 to 15% by weight of tin powder, (2) a sintered body,
Nickel, silver, zinc, tungsten, cobalt, iron,
The lapping plate according to claim 1, which contains at least one metal powder selected from lead, magnesium and manganese, (3)
The lapping plate according to claim 1, wherein the sintered body contains a solid lubricant,
(4) The lapping plate according to item 1, wherein diamond abrasive particles are used as loose abrasive particles, and (5) the lapping plate according to item 1 or 4, which is used for lapping steel balls for rolling bearings. To provide.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A lapping plate according to the present invention is a lapping plate for polishing in which the surface of a workpiece is wrapped using free abrasive grains. Wt%, more preferably 35-60 wt%, bronze powder 10
It is a lapping plate made of a sintered body containing 80% by weight, more preferably 25 to 60% by weight, and 0 to 15% by weight, more preferably 5 to 12% by weight of tin powder. There is no particular limitation on the copper powder used in the present invention. For example, electrolytic copper powder for powder metallurgy, sprayed copper powder specified in JIS H 2114, JIS
Pulverized product of electrolytic copper ingot specified in H2121 can be used. Bronze is usually 2-35% tin by weight
The bronze powder used in the present invention is not limited to a copper-tin alloy, but may be, for example, JIS H 220
Bronze alloy ingot for casting specified in 3 above, JIS H220
Phosphor bronze alloy ingot for casting specified in JIS H4
Aluminum bronze alloy metal for casting specified in 206;
Examples include pulverized products such as lead bronze alloy ingots for casting specified in JIS H 2207. There is no particular limitation on the tin powder used in the present invention, for example, JIS H210
And the like.

[0006] The lapping plate of the present invention comprises a sintered body containing copper powder, bronze powder, and tin powder optionally blended. Brinell hardness of copper is about H _B 50, although Brinell hardness of tin is about H _B 5, Brinell hardness of the alloy obtained by blending tin copper, increases with tin content,
Tin content of 32% by weight reaches a maximum value of H _B 390. Copper powder, bronze powder, and, if necessary, supplying a polishing liquid containing diamond abrasive grains and the like as free abrasive grains to the lap surface plate of the present invention composed of a sintered body containing tin powder, if necessary, The grains dig into the copper powder on the working surface of the platen, half are embedded in the lap platen, and half have a shape protruding a sharp tip, as if the lap platen surface was covered with a single layer of free abrasive grains Lapping is performed in such a state. For this reason, since the loose abrasive particles once embedded in the lapping plate do not fall off the lapping plate and are not lost, it can continuously contribute to lapping and can efficiently perform lapping. . In the lapping plate of the present invention, when the copper powder is less than 20% by weight, the area where free abrasive grains bite into the platen working surface becomes too small, and the lapping efficiency may be reduced. 70 copper powder
If the content is more than 10% by weight, the rigidity of the lap plate decreases, and the lap plate is deformed under pressure, and the lapping accuracy may be reduced.

The lapping plate of the present invention contains a bronze powder having high hardness, thereby increasing the rigidity of the lapping plate, preventing deformation under pressure during lapping, and improving lapping accuracy. . In addition, since free abrasive grains such as diamond abrasive grains do not penetrate into the bronze powder on the surface of the platen, the amount of free abrasive grains used is reduced, and the content of the bronze powder is adjusted. The degree of concentration can be adjusted. In the lapping plate of the present invention, if the content of the bronze powder is less than 10% by weight, the rigidity of the lapping plate is reduced and the lapping plate is deformed under pressure, and the lapping accuracy may be reduced. 8 bronze powder content
If the content exceeds 0% by weight, the area of the free abrasive grains that bites into the working surface of the surface plate becomes too small, and the lapping efficiency may be reduced. The lapping plate of the present invention has improved sintering characteristics by containing tin powder. Sintering is a phenomenon in which when an aggregate of solid powder is heated to a temperature lower than the melting point or a temperature at which a liquid phase is partially formed, it is sintered to form a dense, high-strength polycrystal. Focusing on two particles in the powder, the two particles that are in contact with each other do not have the minimum surface energy, are in a thermodynamic non-equilibrium state, and mass transfer occurs in the direction of decreasing the surface energy. In addition, bonding occurs between the particles. Although a mixture of copper powder and bronze powder can be sintered, the addition of tin powder allows sintering at lower temperature and lower pressure. Since the tin powder is soft, most of the free abrasive grains that have penetrated the tin powder have a form as if embedded in a lapping plate, and the contribution to lapping is small. In the lapping plate of the present invention, when the content of the tin powder exceeds 15% by weight, the ratio of free abrasive grains contributing to lapping decreases, and the lapping efficiency decreases.
There is a possibility that the rigidity of the lapping plate is reduced and the lapping plate is deformed under pressure and the lapping accuracy is reduced.

The sintered body constituting the lapping plate of the present invention is:
Nickel, silver, zinc, tungsten, cobalt, iron,
At least one metal powder selected from lead, magnesium and manganese can be contained. nickel,
By including at least one metal powder selected from silver, zinc, tungsten, cobalt, iron, lead, magnesium and manganese, mechanical properties such as strength and toughness can be improved. In the lapping plate of the present invention, nickel, silver, zinc, tungsten, cobalt,
The content of at least one metal powder selected from iron, lead, magnesium and manganese is preferably 10% by weight or less. Nickel, silver, zinc, tungsten,
If the content of at least one metal powder selected from cobalt, iron, lead, magnesium and manganese exceeds 10% by weight, the strength of the lapping plate may decrease, or the metal may be eluted from the lapping plate. is there. The sintered body constituting the lapping plate of the present invention can contain a solid lubricant. Examples of the solid lubricant include graphite, molybdenum dioxide, and boron nitride. Among them, graphite can be particularly preferably used. By including a solid lubricant,
Lubricity can be improved and grinding resistance can be reduced.
The content of the solid lubricant in the sintered body is preferably 15% by weight or less, more preferably 2 to 8% by weight. If the content of the solid lubricant exceeds 15% by weight, sintering may be difficult.

In the lapping plate of the present invention, the average particle size of the metal powder is preferably 1 to 50 μm, and 2 to 3 μm.
More preferably, it is 0 μm. If the average particle size of the metal powder is less than 1 μm, the productivity of the lapping plate may decrease. If the average particle size of the metal powder exceeds 50 μm, the distribution of the free abrasive grains held in the metal powder may be uneven. The metal powder used preferably has a small width of the particle size distribution. There are no particular restrictions on the free abrasive grains used when using the lapping plate of the present invention, and examples thereof include natural diamond abrasive grains, artificial diamond abrasive grains, cBN abrasive grains, silicon carbide abrasive grains, aluminum oxide abrasive grains, and cerium oxide abrasive grains. And boron carbide abrasive grains. Among these, diamond abrasive grains having high affinity with the lapping plate of the present invention can be particularly preferably used. When diamond abrasive grains are used in the lap surface plate of the present invention, diamond abrasive grains dig into the copper powder on the surface of the surface plate, half of the surface is embedded in the lap surface plate, and half has a shape protruding a sharp tip, Lapping is performed by forming a state in which the surface of the lap platen is covered with a single layer of diamond abrasive grains. For this reason, the diamond abrasive grains once embedded in the lapping plate are fixed to the lapping plate, and do not fall off the lapping plate and are lost. Wrapping can be performed.
In addition, since the height of the cutting edge of the diamond abrasive grains is easy to be uniform, high surface smoothness is obtained, and it is possible to efficiently wrap hard brittle materials and steel balls.

The grain size of the diamond abrasive grains used in the lapping plate of the present invention is not particularly limited, but may be from 0 / 0.1 to 20/3.
0 μm, preferably 0.5 / 0.5 to 6/12 μm
m is more preferable. The lap surface plate of the present invention
It is particularly effective when using fine loose abrasive grains.
There is no particular limitation on the method for supplying free abrasive grains to the lapping plate of the present invention.For example, the free abrasive particles can be supplied as they are on the lapping plate, or the free abrasive particles can be supplied with water or water. It can also be supplied as a polishing liquid dispersed in oil. There is no particular limitation on the method of supplying the polishing liquid. For example, the polishing liquid can be supplied continuously or intermittently. The workpiece to be wrapped using the lapping plate of the present invention is not particularly limited, and examples thereof include hard and brittle materials such as ceramics, super hard metals, steel, and ferrite. Among them, the recording capacity is increasing, the recording density is increasing, the rotation speed of the disk is required to be high, and the flying distance of the head from the disk surface is required to be shortened. It can be particularly suitably used for wrapping steel balls for rolling bearings.
By performing lapping using the lap surface plate of the present invention, it is possible to produce a steel ball for a rolling bearing having fine surface roughness, good sphericity, and excellent undulation accuracy.

[0011]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 Dimension 400D-40 consisting of a sintered body of copper powder, bronze powder and tin powder and containing graphite as a solid lubricant
A lap surface plate of T-240H was produced. Average particle size 20μ
60 wt% of copper powder, 30 wt% of bronze powder having an average particle diameter of 20 μm having three kinds of compositions specified in JIS H 2203, 5 wt% of tin powder having an average particle diameter of 20 μm, and 5 wt% of graphite The material was filled in a mold having a predetermined size, and was sintered by heat compression at a temperature of 600 ° C. and a pressure of 50 MPa for 1 hour. Further, 15 concentric grooves with a width of 2 mm and a depth of 0.5 mm were machined on the surface by cutting.
A lap plate was obtained. Using the obtained lap plate as a rotating plate and a fixed plate, material SUJ2, hardness Hv790 (H
RC65), wrapping of a 2 mm nominal ball bearing steel ball. The lapping plate was mounted on a horizontal axis ball grinder [manufactured by Nishida Machinery Co., Ltd.], and the particle size was 30,000 (0 / 0.5μ).
m) Light oil containing 4% by volume of diamond abrasive grains was used as a polishing liquid, the rotation speed was 20 rpm, the load was 1.0 N / sphere, the number of injections was 4,800, the total number of injections was 100,000 / lot, and the processing time was Lapping was performed under the conditions of 9 hours / lot. A total of 90 wrapped steel balls were sampled, 10 pieces every 1 hour of processing time, and the surface roughness (Ra) and sphericity were measured according to JIS B1501. Finally, the surface roughness is 1.2 to 1.4 nm, and the sphericity is 8 to 10
nm. In addition, the wrapped steel ball is incorporated into the outer ring and inner ring of the deep groove ball bearing, and 1,000 to 1,800 rpm
Turned at. Compared to using steel balls wrapped using a lap plate made of meehanite cast iron,
The amplitude of the vibration waveform at the time of rotation was 50% or less, and the beat noise was significantly reduced. From this result, it was confirmed that the undulation accuracy of the ball was excellent. Example 2 A sintered body of copper powder, bronze powder, tin powder, nickel powder, silver powder, zinc powder, tungsten powder, cobalt powder, iron powder, lead powder, magnesium powder, and manganese powder was used. A lapping plate having a size of 400D-40T-240H containing molybdenum was prepared. The average particle diameters of the metal powders are all 20 μm. 57% by weight of copper powder, 30% by weight of bronze powder having three kinds of compositions specified in JIS 2203, 8% by weight of tin powder, 0.5% by weight of nickel powder, 0.8% by weight of silver powder, 0.3% of zinc powder Wt%, tungsten powder 0.3 wt%, cobalt powder 0.3 wt%, iron powder 0.2 wt%, lead powder 0.2 wt%, magnesium powder 0.2 wt%, manganese powder 0.3 wt%.
A lapping plate was prepared in the same manner as in Example 1 by using a powdery substance in which 2% by weight and 2% by weight of molybdenum dioxide were mixed. Using the obtained lap surface plate as a rotating disk and a fixed disk, lapping of the ball for a ball bearing was performed in the same manner as in Example 1, and the surface roughness and sphericity were measured. Finally, the surface roughness was 1.1 to 1.3 nm and the sphericity was 7 to 9 nm. Comparative Example 1 100,000 pieces / lot, machining time 9 under the same conditions as in Example 1 except that a lap plate having the same shape and the same dimensions as those of the lap plate of Example 1 made of meehanite cast iron was used.
At time / lot, steel balls for ball bearings were wrapped and evaluated. The surface roughness was 1.5 to 2.0 nm, and the sphericity was 10 to 13 nm. Table 1 shows the results of Examples 1 and 2 and Comparative Example 1.

[0012]

[Table 1]

As can be seen from Table 1, the steel balls of Examples 1 and 2 wrapped using the lapping plate of the present invention have the same surface roughness (Ra) and sphericity as those of conventional cast iron. The precision is better than the steel ball of Comparative Example 1 wrapped using a lap surface plate.

[0014]

According to the lapping plate of the present invention, since soft copper powder and slightly hard bronze powder are mixed on the working surface, the retention of free abrasive grains is good, and the lapping plate Hardness and viscosity are obtained, and dimensional stability is excellent. Therefore,
By performing lapping using the lapping plate of the present invention, steel balls and the like that require extremely high precision, such as those used in rolling bearings of hard disk drives, can be finished with excellent surface roughness and sphericity.

Claims (5)

[Claims] 1. A polishing lap surface plate for lapping the surface of a workpiece using free abrasive grains, wherein the surface of the surface of the polishing plate is
A lapping plate comprising a sintered body containing 20 to 70% by weight of copper powder, 10 to 80% by weight of bronze powder and 0 to 15% by weight of tin powder. 2. The lapping plate according to claim 1, wherein the sintered body contains at least one metal powder selected from nickel, silver, zinc, tungsten, cobalt, iron, lead, magnesium and manganese. 3. The lapping plate according to claim 1, wherein the sintered body contains a solid lubricant. 4. The lapping plate according to claim 1, wherein diamond abrasive grains are used as free abrasive grains. 5. The lap plate according to claim 1, which is used for lapping steel balls for rolling bearings.