JPH0241866A - Polishing device using magnetic fluid - Google Patents

Abstract

PURPOSE:To obtain the spherical body whose sphericity is extremely excellent by holding a guide ring freely slidably in the horizontal direction. CONSTITUTION:A magnetic field is formed on a magnetic fluid 7 by a magnetic field forming means 6 and a floating power is given to a float 5 together with this magnetic fluid 7. The spherical body 3 to be polished is subjected to polishing by holding it in the magnetic fluid 7 with this float 5, driving lap 1 and the guide ring 4 internal wall face. In this case, the guide ring 4 is held slidably in the horizontal direction and the sphericity of the spherical body 3 is increased.

Description

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

[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 is disclosed in Japanese Patent Application Laid-open No. 173166/1983.
It is disclosed in the publication No. The polishing method and device described in the publication apply ejection force to a sphere immersed in a magnetic fluid by the action of an external magnetic field acting from one side outside the magnetic fluid, and drive the sphere to be positioned on the opposite side. The sphere is pressed against the surface of a driving jig (driving lap), thereby transmitting the movement of the driving jig to the sphere to move it in the magnetic fluid, and the movement of the sphere is controlled by a guide surface. It is.

For example, a guide surface has been disclosed in which a V-shaped groove or a partition plate is provided on the lower surface of the drive wrap to function as a guide surface.

Furthermore, if a buoyancy plate (float) is inserted so as to be located on the external magnetic field side of the sphere, this buoyancy plate also has an external 6! It is disclosed that the ejecting force due to the action of the i-field is applied and the sphere is more strongly pressed against the polishing surface of the driving jig, so that the polishing efficiency is significantly improved.

In addition, as a modification of this device, the lower end of the drive wrap is shaped like an inverted triangular pyramid, and the sphere becomes the slope of an inverted pentagonal pyramid, or the cylindrical container (
There is also a device that aims to improve the sphericity by polishing by moving it while being pressed between it (a guide ring) and a buoyancy plate.

In either case, the lower part of the apparatus is supported by an XY table, which allows the positional relationship between the lower part of the apparatus and the drive wrap to be adjusted.

For example, FIG. 6 is a sectional view showing an example of a conventional polishing apparatus. In the figure, 1 is the driving lap, 2 is the contact surface with the spherical object to be polished, 3 is the spherical object to be polished (the spherical object to be polished), 4 is the guide ring, 5 is the float, 6 is the magnet, and 7 is the abrasive grain. 8 represents a table, and 12 represents an XY table.

A guide ring 4, a float 5 immersed in a magnetic fluid 7,
Equipped with a rotatable driving lap l and a magnet 6 that forms a magnetic field in the magnetic fluid 7 and gives a levitation force to the float 5 together with the magnetic fluid 7, it drives the spherical object 3 to be polished! Polishing is carried out by rotating the driving lap 1 while holding it in the magnetic fluid 7 by the inner wall surfaces of the float 5 and the guide ring 4 which are subjected to a buoyancy force.

The guide ring 4 is fixed to the XY child table 2 together with the magnet 6, and by moving the XY child table 2 in the horizontal direction, the center of the drive wrap 1 and the center of the guide link 4 are aligned.

[Problems to be Solved by the Invention] However, in order to align the center using this method, a precise XY table with a positioning accuracy of several μm or more is required. There is a problem that a positional shift of about several tens of micrometers occurs. For this reason, it has not always been possible to obtain a sphere having sufficient sphericity.

In view of the problems of the prior art, an object of the present invention is to
An object of the present invention is to further improve the sphericity of a sphere in a polishing device using magnetic fluid.

[Means and effects for solving the problem] In order to achieve the above-mentioned object, the inventors of the present invention have made extensive studies to achieve the above-mentioned object. The present invention was completed based on the finding that the sphericity of the sphere is improved.

That is, the present invention includes a guide ring, a float immersed in a magnetic fluid, 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 comprising: a polishing device for polishing a spherical workpiece by rotating the bibulous lap while holding the spherical workpiece in the magnetic fluid by the driving lap, a float receiving a buoyant force, and an inner wall surface of the guide ring; This polishing device is characterized by being provided with means for horizontally slidably holding the link.

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 the polishing apparatus of the present invention.

In the figure, 1 is the driving lap, 2 is the contact surface with the spherical object to be polished, 3 is the spherical object to be polished (the spherical object to be polished), 4 is the guide ring, 5 is the float, 6 is the magnet, and 7 is the abrasive grain. 8 is a table, 9 is a free bearing ball, 10 is a magnetic fluid containing
11 indicates the fixed ring of the free bearing, 11 indicates the free bearing, and E indicates the inclination angle of the contact surface at the lower end of the drive wrap.

In this polishing device, a float 5 is immersed in a magnetic fluid 7, and an external magnetic field is applied to the magnetic fluid 7 using a magnet 6, etc.
The float 5 is raised by the float force, and the spherical object 3 to be polished is placed between the contact surface of the upper surface of the float 5 and the driving lap 1.
It is held by the contact surface 2 at the lower end 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, and the spherical object 3 moves in the magnetic fluid 7. Polishing is performed by applying relative motion between the spherical body 3 to be polished and the magnetic fluid 7 containing abrasive grains. At this time, Fn
The guide ring 4 is held horizontally slidably together with the magnet 6 by a free bearing 11 consisting of a ball 9 and a fixed ring 10 arranged under the magnet.

The drive wrap 1 is capable of horizontal rotation about a vertical axis, and the inclination angle E of the contact surface 2 is preferably in the range of 20 to 80 degrees.

The material of the drive wrap 1 is not particularly limited, but includes, for example, stainless steel such as SO5304, metals such as brass, and aluminum.

The inner wall surface of the guide ring 4 is preferably lined with rubber, resin, or the like to suppress vibration of the guide ring.

The float 5 is given a levitation force by the action of an external magnetic field such as a magnet 6 and floats, thereby strongly pressing the spherical object 3 to be polished against the contact surface 2 and the like at the lower end of the drive wrap 1 . This float 5 is connected to the contact surface 2 of the drive pump 1 and the guide ring 4.
Together with the inner wall surface of the polishing member, the rotating sphere 3 to be polished is maintained in a constant circular orbit during polishing, thereby contributing to an improvement in sphericity. The shape of the float 5 in contact with the spherical object 3 to be polished may be a flat or tapered shape that contacts at a negative point, or a V-shaped or arcuate cross section that contacts at two points or a circumferential portion. A recess may be provided.

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

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

It is not an absolute condition that the specific gravity of the float 5 is lighter than the specific gravity of the magnetic fluid 7, but it is sufficient that the floating force is generated by the action of an external magnetic field acting from below.

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

As the abrasive grains contained in the magnetic fluid, known polishing abrasive grains can be appropriately selected and used. For example AJZ203
(corundum), 5iC (silicon carbide-carborundum), diamond, etc., or abrasive grains with added magnetism may be used.

Further, instead of containing abrasive grains in the magnetic fluid, a method may be used in which the abrasive grains are fixed to the contact surface 2 of the lower end of the driving lap 1 which contacts the spherical body 3 to be polished. Of course, fixed abrasive grains and free abrasive grains may be used at the same time.

The magnet 6 used as the external magnetic field may be a single magnet, a group of magnets arranged with the same polarity, or a group of magnets combined so that adjacent magnets have different polarities (indicated by arrows in the figure). This magnet or group of magnets may be a permanent magnet or an electromagnet.

In the present invention, as described above, the ball 9 is placed under the magnet 6.
and a sliding means such as a free bearing 11 consisting of a fixed @IO. Therefore, the guide ring 4 is in a state where it can slide in a plane direction perpendicular to the rotational axis of the drive wrap 1, and when the spherical object 3 to be polished is set in this state, the drive wrap 1 and the guide ring 4 come into contact with the spherical object 3 to be polished. By doing so, the gap between the drive wrap l and the guide ring 4 becomes almost constant, and the centers thereof align. And driving lap 1
The more the polishing progresses and the sphericity of the polished sphere 3 improves, the more accurately the centers of the drive lap l and the guide ring 4 coincide, and as a result, the sphericity of the polished sphere 3 increases. Further improvement.

2 and 3 are diagrams showing the structure of a free bearing used in the polishing apparatus of FIG. 1. FIG.

Three or more balls 9 are filled in the groove of the fixed ring 10, and by interposing the balls 9 between the magnet 6 and the fixed ring 10, the guide ring 4 can be slid in the horizontal direction.

The free bearing 11 is not limited to those shown in FIGS. 2 and 3, and the guide ring 4 can be used at three or more points.
Any device that can hold the lower part of the device and allow the guide ring 4 to slide in the horizontal direction may be used.

FIG. 4(a) is a diagram showing another example of means for making the guide ring 4 slidable. FIG. 2B is an enlarged sectional view of the free bearing 13, in which a ball 15 much smaller than the ball 14 is interposed between the ball 14 and the ball receiver 16. The guide ring 4 is held by the free bearing 13 via the magnet 6, thereby allowing the guide ring 4 to slide horizontally.

FIG. 5 is a diagram showing still another example of means for making the guide ring 4 slidable. Through the air outlet 17, arrow 1
By blowing air, oil, etc. onto the lower surface of the magnet 6 in the direction of 8, the guide ring 4 is slightly floated together with the magnet 6, so that the guide ring 4 can slide horizontally.

The material of the balls 9, 14 and 15 is not particularly limited, but steel, bearing steel, alloy steel, ceramics, etc. are preferably used.

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

[Examples] The present invention will be explained in more detail below based on Examples and Comparative Examples.

Example 1 A polishing test was conducted using the polishing apparatus shown in FIG. However, as a free bearing, the outer diameter of the groove is 40 mm and the inner diameter is 20 mm as shown in Figures 2 and 3.
, in a fixed ring with a depth of 5 ml11, a diameter of 7 mm, and a sphericity of 1.
The drive wrap is made of SO5304 and has a contact surface of 60 degrees, the float is made of acrylic and has a disc shape with a diameter of 35 mm and a thickness of 2 mm, and the guide ring has an inner diameter of 10 μm steel balls. A 37 mm piece lined with urethane was used. A dead weight method was adopted as the lap pressurizing means. The test conditions are as follows.

Test condition Pressure pressure 400g Wrap rotation speed: 9000r, p, m.

Magnetic fluid To40 (manufactured by Taihohe Co., Ltd.) 10
mll Abrasive grain GC# 6000 Sphere to be polished Material 'Jit, Si3N4 Diameter 7
．． 3 mm Sphericity 2 μm Number of balls 11 Polishing time 40 minutes The results of the polishing test are shown in Table 1.

Comparative Example 1 A polishing test was conducted under the same conditions as in Example 1, except that the guide ring was fixed to the XY child table without using a free bearing.

The results of the polishing test are shown in Table 1.

As is clear from the above Examples and Comparative Examples, in a polishing device using magnetic fluid, if a free bearing is placed under the guide ring so that the guide ring can slide horizontally, polishing will result in the free bearing being placed below the guide ring. It can be seen that the sphericity of the polished sphere is significantly improved compared to the case where the guide ring is fixed on the ×Y table without polishing.

[Effects of the Invention] As explained above, according to the polishing apparatus of the present invention, it is possible to obtain a sphere with extremely excellent sphericity.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an example of a polishing device according to the present invention, FIG. 2 is a side sectional view showing an example of a free bearing according to the present invention, FIG. 3 is a plan view of the free bearing shown in FIG. 2, Figure 4 (
a) is a side sectional view showing another example of the guide ring sliding means according to the present invention, FIG. 5(b) is an enlarged side sectional view of the free bearing part, and FIG. FIG. 6 is a side sectional view showing an example of a conventional polishing apparatus. 1: 2; 3: 4: 5: 6; 7: 8: 9. 10: 11. 12: 16 = 17: 18: E: Drive wrap, contact surface at the lower end of the drive wrap, polished sphere, guide ring, float, magnet, magnetic fluid containing abrasive grains, table, 14.15: Ball, fixed ring, 13: Free bearing, xY table, ball receiver, blowout hole, arrow indicating the direction of air flow, angle of inclination of the contact surface at the lower end of the drive wrap. Fig. Fig. [ / No.

Claims (1)

[Claims] 1. A guide ring, a float immersed in a magnetic fluid, 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, and has a spherical shape. In a polishing device, the workpiece to be polished is held in the magnetic fluid by the driving lap, a float receiving a buoyant force, and the inner wall surface of the guide ring, and the guide ring is held horizontally by rotating the driving lap. A polishing device characterized in that it is provided with means for holding the polishing device so as to be slidable in the direction.