JPH01271165A - Polishing device using magnetic fluid - Google Patents

Abstract

PURPOSE:To obtain a ball unit of high sphericity while continuing a workpiece to be properly held and facilitated in its setting to a proper position by providing a movement preventing surface, which prevents the workpiece from moving in the radial direction of a driving lap, in a float in its upper end part. CONSTITUTION:While a spherical workpiece 3 is held is magnetic fluid 7, containing an abrasive grain, by a driving lap 1, float 5 receiving levitating force by a magnetic field formed by a magnet 6 and the internal peripheral surface of a guide ring 4, the workpiece 3 is polished by rotating the driving lap 1. Here the flat 5 forms in its upper end part a movement preventing surface 8 for preventing the workpiece 3 from moving in the axial direction of the driving lap 1. As a result, the workpiece 3 can be easily arranged along this movement preventing surface 8 in a peripheral edge part of the flat 5, and setting the driving lap 1 from the upper enabling the workpiece 3 to be surely held to a proper position, a ball unit of high sphericity can be obtained by preventing movement of the workpiece 3, when it is polished, by rotating the driving lap 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a polishing device using a magnetic fluid, and more specifically, a polishing device that uses a magnetic fluid containing abrasive grains under the action of a magnetic field to polish a ball bearing or the like. It relates to an apparatus for efficiently manufacturing spheres with high sphericity by polishing the spheres used.

[Prior Art] Conventionally, a method and apparatus for polishing spheres used in ball bearings, etc. using a polishing liquid made of a magnetic fluid containing abrasive grains under the action of a magnetic field has been disclosed in Japanese Patent Laid-Open No. 17316/1983.
It is disclosed in Publication No. 6. The polishing method and device described in the publication apply ejection force to a sphere immersed in a magnetic fluid containing abrasive grains by the action of an external magnetic field acting from one side outside the magnetic fluid, and then The movement of the driving jig (driving lap) is transmitted to the sphere, causing it to move in the magnetic material containing the abrasive grains, and the movement of the sphere is is characterized in that it is controlled by a guide surface.

Also, at this time, if a buoyancy plate (float) is inserted so as to be located on the external magnetic field side of the sphere, ejection force is also applied to this buoyancy plate due to the action of the external magnetic field, and the sphere is more strongly pushed to the drive surface of the driving jig. It is disclosed that the polishing efficiency is significantly improved by pressing against the surface.

In the polishing device, in order to control the movement of the sphere, a V-shaped groove and a partition plate are provided on the lower surface of the driving lap, and the plate functions as a guide surface for the movement of the sphere, thereby improving polishing efficiency and sphericity. There is. Another method is to make the lower end of the drive lap into an inverted triangular pyramid shape and polish it by moving the sphere while being pressed between the slope of the inverted pentagonal pyramid, the cylindrical container (guide ring), and the buoyancy plate. We are trying to improve the sphericity.

[Problem to be Solved by the Invention] However, according to the above-mentioned conventional example, when the sphericity of the raw sphere to be polished is not good, that is, especially immediately after the start of polishing, severe damage occurs due to the revolution and rotation of the polished sphere. Vibration or impact from the guide ring, etc. may cause the ball to move or get stuck inside the drive lap, reducing polishing accuracy or not being polished at all, resulting in a decrease in polishing efficiency and sphericity. It has the disadvantage of inviting

Furthermore, when setting the raw balls in the polishing device, since the balls roll, it is not easy to arrange the balls along the inner wall surface of the guide ring and set the drive lap, which results in low work efficiency.

In view of the problems of the prior art, it is an object of the present invention to move a spherical object to be polished using a driving lap, a float that receives a levitation force through a magnetic fluid by a magnetic field, and a guide ring using a magnetic fluid containing abrasive grains. An object of the present invention is to further improve the sphericity and polishing efficiency of a sphere in a polishing device using a magnetic fluid, which polishes by rotating a driving lap while holding the sphere inside.

[Means and effects for solving the problem] As a result of intensive studies to achieve the above object, the present inventors have found that the object to be polished moves in the axial direction of the drive lap, that is, inwardly, at the upper end of the float. By providing a movement prevention surface that prevents this from happening, the present invention has been completed in which the object to be polished can be properly held and the sphericity of the sphere and the polishing efficiency are improved.

That is, the present invention includes a guide ring, a float immersed in a magnetic fluid containing abrasive grains, a rotatable drive wrap, and a magnetic field that forms a magnetic field in the magnetic fluid and gives a levitation force to the float together with the magnetic fluid. A polishing method in which a spherical object to be polished is held in the magnetic fluid by the driving lap, a float subjected to a buoyant force, and the inner wall surface of a guide ring, and the driving lap is rotated to polish the object. The apparatus is characterized in that the upper end of the float is provided with a movement prevention surface that prevents the object to be polished from moving in the axial direction of the drive lap and maintains proper retention of the object to be polished. This is a polishing device that uses magnetic fluid.

Hereinafter, a polishing apparatus using a magnetic fluid according to the present invention will be explained based on the drawings.

FIG. 1 is a sectional view showing an example of a polishing apparatus of the present invention. In the figure, 1 is a driving lap, 2 is a contact surface of the lower end of the driving lap with a spherical object to be polished, 3 is a spherical object to be polished (a spherical object to be polished), 4 is a guide ring, 5 is a float, 6 is a magnet, Reference numeral 7 indicates a magnetic fluid containing abrasive grains, and reference numeral 8 indicates a movement prevention surface provided on the float 5.

In the polishing apparatus shown in FIG. 1, a magnetic fluid 7 containing abrasive grains is used.
The float 5 is immersed in the liquid, and an external magnetic field is applied to the magnetic fluid 7 using a magnet 6 or the like to give buoyancy to the float 5. The float 5 is raised by the buoyancy, and the sphere 3 to be polished is brought into contact with the upper end of the float 5. It is held by the contact surface 2 of the lower end of the drive wrap 1 and the inner wall surface of the guide ring 4. Then, by driving the driving lap 1 and rotating it in the horizontal direction, the movement of the rotation is transmitted to the spherical object 3 to be polished, so that it moves in the magnetic fluid 7 containing abrasive grains. This polished sphere 3
By generating a relative movement between the magnetic fluid 7 containing the abrasive grains, polishing is efficiently performed on the surface where the spherical object 3 to be polished is held, particularly on the tapered contact surface 2 at the lower end of the drive lap 1. It will be done.

The drive lap 1 shown in the polishing apparatus of FIG. 1 is capable of horizontal rotation about a vertical axis and has a contact surface 2 at its lower end. Further, since the driving lap 1 is worn out by polishing the spherical body 3 to be polished, it is necessary to lower the driving lap 1 each time, so that vertical movement is also possible. This contact surface 2 plays an important role in holding the spherical object 3 to be polished on the orbit between the float 5 and the inner wall surface of the guide ring 4, and for stable and smooth rotational polishing. Contribute to the improvement of Here, when the inclination angle E of the contact surface 2 in the outer circumferential direction with respect to the vertical direction is 20 to 80 degrees, the sphericity of the sphere can be improved. If the inclination angle E of the contact surface 2 exceeds 80 degrees, the force pressing the sphere 3 to be polished against the inner wall surface of the guide ring 4 will be weak, and if it is less than 20 degrees, the contact surface will not effectively press the sphere 3 to be polished. Since no processing pressure is applied from 2,
In each case, the motion of the polished sphere 3 becomes unstable and the sphericity does not improve, which is not preferable.

Alternatively, the drive wrap 1 may have a cylindrical shape as shown in FIG. 2, and in this case as well, the angle of inclination E of the contact surface is preferably in the range of 20 to 80 degrees.

The material of the driving lap 1 is not particularly limited in the case of rough machining, and examples include stainless steel such as 5TLS304, metals such as brass, aluminum, etc., and in the case of finishing, brittle materials such as cast iron, ceramics, resin, etc. Preferably, it is made of material.

The inner wall surface of the guide ring 4 provided in the polishing apparatus shown in FIG. 1 is preferably lined with rubber, resin, or the like to suppress vibration of the guide link.

Next, the float 5 immersed in the magnetic fluid of the polishing device is
Buoyancy is applied by the action of an external magnetic field such as the magnet 6, and the float 5 floats to strongly press the spherical object 3 to be polished against the contact surface 2 of the lower end of the drive lap 1. This float 5 is
Together with the contact surface 2 of the driving lap 1 and the inner wall surface of the guide ring 4, the rotating spherical object 3 to be polished is held constant during polishing, contributing to improvement in sphericity.

In the present invention, a movement preventing surface 8 is provided at the upper end of the float 5 in order to prevent the polished sphere 3 from moving in the axial direction of the drive lap 1. There are various aspects of this movement prevention surface 8, and FIGS. 3(a) to 3(d) show 4i.
It is a sectional view of a float 3 illustrating type 11. The movement prevention surface 8a provided on the float shown in FIG. 2(a) is provided as a groove extending around the entire circumference of the float having an arcuate cross section.

The radius R of this arc is, if the diameter of the polished sphere is D,
It is preferable that R=D/2 to D, and the depth H of the groove is preferably in the range of )1=0.050 to 0.3D. However, the thickness of the float is t
Then, the depth H of the groove is preferably H≦y2t in consideration of the strength and life of the float.

The movement prevention surface 8b shown in FIG. 2B is of a similar groove type with a V-shaped cross section. The apex angle α of this V-shape is preferably in the range α; 90＠ to 135°, and the angle β between the inner slope of the V-shaped groove and the horizontal plane is in the range β=45° to (110”). It is preferable that α+β≦1800.Similarly, the depth H of the groove is H≦%
Preferably, t.

The inner slopes of these arc-shaped and V-shaped grooves, that is, the slopes on the center side of the float, function as movement prevention surfaces 8a and 8b.

The float shown in Figure (c) has an upper outer circumferential portion that is L over the entire circumference.
It has a shape cut out into a letter shape, and its vertical surface functions as a movement prevention surface 8c. This corresponds to the case where α and β are set to α=90′ β=906 in the case where the V-shaped groove is provided.

The float shown in FIG. 3(d) has a tapered surface on its upper outer peripheral portion, and this tapered surface functions as a movement prevention surface 8d.

The angle θ between this Taber surface and the horizontal plane is θ=201~60° It is preferable that

As the material of the float 5, various materials such as metal, plastic, ceramics, rubber, etc. can be appropriately selected and used.

The buoyant force acting on the float 5 is determined by the strength of the external magnetic field acting from below, the size of the float 5, the distance from the magnet 6 etc. to the float 5, etc., and by changing these, the required processing pressure can be controlled arbitrarily. can do.

The specific gravity of the float 5 is lif! which contains abrasive grains! It is not an absolute condition that the specific gravity be lighter than the specific gravity of the sexual fluid 7, but it is sufficient as long as the buoyancy is generated by the action of an external magnetic field acting from below.

As the magnetic fluid 7, one in which ferrite, magnetite, etc. are dispersed using water or oil as a medium is used.

As the abrasive grains contained in the magnetic fluid 7, known polishing abrasive grains can be appropriately selected and used. For example, A';12
0s C corundum), 5iC (silicon carbide dicarborundum), diamond, etc., or abrasive grains with added magnetism may be used.

The magnet 6 used as the external magnetic field may be a single magnet or a group of magnets arranged with the same polarity, but it is rather arranged so that the polarities of adjacent magnets are different from each other (as indicated by the arrows in the figure).
Preferably, it is a combined magnet group. Combining the magnet group so that the poles of adjacent magnets are different from each other increases the buoyancy of the abrasive grains and the float 5, and also causes magnetic displacement force to act in the horizontal direction, so as to resist the direction of movement of the sphere 3 to be polished. This is to keep the abrasive grains in place. This magnet or group of magnets may be a permanent magnet or an electromagnet.

Further, as the polished sphere 3 applied to the present invention, Si
Those made of ceramics such as 0% Si3N4 or other metals are used, and the polished spheres are used for applications such as ball bearings.

In addition, although the spherical object to be polished has been described in the present invention,
It is possible to polish not only spherical objects but also flat plates, cylinders, etc.

In the present invention described above, the movement prevention surface 8 as described above is used.
Since the float 5 with
The drive wrap 1 can be set from above and reliably held in a proper position. In addition, when polishing by rotating the driving lap 1, the spherical object 3 to be polished with low sphericity immediately after the start of polishing receives an impact force from the guide ring 4, etc., and applies a strong force inward to the driving lap 1. Even if the drive wrap 1 is moved inwardly, the movement prevention surface 8 prevents the drive wrap 1 from moving inward. Therefore, the spherical body 3 to be polished is always properly held and guided by the drive lap 1, float 5, and guide ring 4, and polishing is performed without causing polishing defects or redoing, resulting in improved sphericity and Polishing work becomes more efficient.

[Example] The present invention will be explained in detail below.

EXAMPLES 1 TO 4 AND COMPARATIVE EXAMPLES Tests were conducted using a polishing apparatus having the cross-sectional shape shown in FIG. Wrap angle (inclination angle) of the lower end of the mechanical wrap a
The inner diameter of the guide ring is 37 mm, and the inner wall of the guide ring is lined with urethane rubber at the portion that comes into contact with the polished sphere. W-40 manufactured by Taiho Industries was used as the magnetic fluid, and GC#400 was used as the abrasive grain.
is used. Further, the processing load was adjusted to 400 g. The float shown in Fig. 3(a) (Example 1)
), (b) (Example 2), (C) (Example 3), (d)
Five types of flat floats without a movement prevention surface as shown in Example 4 and as a comparative example shown in FIG. 4 are used.

These floats are all made of acrylic and have a thickness and outer diameter of 2 mm and 35 mm. Moreover, the size of the movement prevention surface of each float is R=! for the R-type Example 1 shown in FIG. IQD, H=O105D1 Same figure (b) Nov
For the letter-shaped Example 2, α=90°, β=451, H
= 0.05D, H = 1 mm for the single-shaped embodiment 3 shown in the same figure (c), and taper-shaped embodiment 4 shown in the same figure (d).
For θ=20@.

Using this device, the diameter was 7.7 mm and the sphericity was 50.
Eleven silicon nitride (SisN4) balls of 0 to 600 μm are placed on the float along the movement prevention surface so that the inner wall of the guide ring and the tapered surface of the lower end of the drive wrap, that is, the contact surface, are in contact with the balls. After holding the drive lap at 9000 r,p,m. After several minutes, the rotation of the drive wrap was stopped, and it was confirmed whether the ball had entered the inside of the drive wrap.

The above operation was performed 10 times for each of the above five types of floats.

As a result, in Examples 1 to 4 using floats having movement prevention surfaces shown in FIGS. 3(a) to 3(d), the ball did not move into the drive wrap in any case. In the comparative example shown in FIG. 4 using a flat float without a movement prevention surface, the ball entered the inside of the drive wrap 1 four times out of ten.

[Effects of the Invention] As explained above, according to the present invention, since the float is provided with a movement prevention surface, it is easy to set the object to be polished in the proper position, and the object to be polished can be properly held. Therefore, the efficiency of the polishing work and the sphericity of the object to be polished can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a polishing apparatus of the present invention, FIG. 2 is a side sectional view showing an example of a driving lap used in the present invention, and FIGS. FIG. 4 is a sectional view showing an example of a float used in the polishing apparatus of the invention, and FIG. 4 is a sectional view showing an example of a float used in a conventional polishing apparatus. 1: Drive lap, 2: Drive surface, 3: Sphere to be polished, 4 Ni guide ring, 5: Float, 6: Magnet, 7: Magnetic fluid containing abrasive grains, 8.8a to 8d: Movement prevention surface. (b) P (C) d (d) Figure 4 Procedural Amendment 0. 5゜ August 4, 1988 Director General of the Japan Patent Office Yoshi 1) Moon Takeshi 6゜1, Indication of the case Patent Application No. 94631 of 1988 2, Title of invention Polishing device using magnetic fluid 3, Relationship with the case of the person making the amendment Patent Applicant Address 3-16-8 Kiyamaminami, Sendai City, Miyagi Prefecture Name Kago Haramachi Address 2-2-1 Otemachi, Chiyoda-ku, Tokyo In the specification subject to the amendment, “ "Claims column" and "Detailed description of the invention column" Contents of amendment 1: The scope of claims will be corrected as shown in the attached sheet. 2. Specification, page 4, line 16, page 5, lines 9-10. Correct "axial direction" in line 16 of page 8 to "radial direction." Attached Claim 1: A guide ring, a float immersed in a magnetic fluid containing abrasive grains, a rotatable drive wrap, and a magnetic field is formed in the magnetic fluid to apply a levitation force to the float together with the magnetic fluid. A spherical object to be polished is held in the magnetic fluid by the driving lap, a float receiving a buoyant force, and an inner wall surface of the guide ring, and is polished by rotating the driving lap. 1. A polishing device using a magnetic fluid, characterized in that a movement preventing surface is provided on the upper end of the float to prevent the object to be polished from moving in the direction of the green beans on the driving lap.

Claims (1)

[Claims] 1. A guide ring, a float immersed in a magnetic fluid containing abrasive grains, a rotatable drive wrap, and a magnetic field forming means that forms a magnetic field in the magnetic fluid to give a levitation force to the float together with the magnetic fluid. A polishing apparatus for polishing a spherical object to be polished by rotating the driving lap while holding the spherical object in the magnetic fluid by the driving lap, a float receiving a buoyant force, and an inner wall surface of a guide ring. A polishing device using a magnetic fluid, characterized in that a movement preventing surface is provided at an upper end of a float to prevent the object to be polished from moving in the axial direction of the drive lap.