JPH0227113B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a magnetic polishing apparatus that orients magnetic abrasive in a magnetic field to form an abrasive brush, and uses this brush to polish an object to be polished. In particular, the present invention relates to a magnetic polishing apparatus which is capable of polishing a non-magnetic object to be polished, and can also perform double-sided polishing of a disc-shaped object to be polished.

[Technical background and conventional problems]

The work of polishing an object to be polished involves contacting the object with an abrasive that is harder than the object, and polishing at a speed and pressure depending on the conditions such as the material of the object to be polished and the required polishing accuracy. The agent is made to slide onto the polishing surface.

In this polishing operation, uniform and appropriate pressure of the polishing agent is important in order to precisely polish the polished surface. To achieve this, it is necessary to consider technical innovations such as the material of the lap that holds the abrasive. Conventionally, cloth, rubber, synthetic resin, etc. have been used as this material. Furthermore, recently, polishing devices that utilize magnetism have been considered. An example of this type of magnetic polishing apparatus is one in which a magnetic polishing agent is oriented in a magnetic field to form an abrasive brush, and an object to be polished is polished using this abrasive brush. This type of conventional magnetic polishing apparatus is most suitable for polishing objects in the shape of a rotating body processed by a lathe or the like, such as molds or parts for sewing machines.

On the other hand, in recent years, there have been an increasing number of objects to be polished that require precision polishing. Examples of this type of object to be polished include magnetic disks, magnetic tapes, aluminum disks, synthetic resin disks, and synthetic resin films. These objects to be polished have a relatively wide polishing surface, and must be polished with high precision.

A conventional example of a polishing apparatus for polishing a disk among objects to be polished will be explained with reference to FIG. 5 and FIG. 6, which is a side view thereof. In this polishing apparatus, the disk D is rotationally driven clockwise or counterclockwise in FIG. 5 by a predetermined rotational drive device. Further, a polishing disk 1 faces the disk D from both sides. Each polishing disk 1 is composed of a polishing pad 3 and a rigid plate 4 that supports the polishing pad 3, and the polishing disk 1 is rotatably driven by a rotating shaft 2. The polishing pad 3 is made of polyurethane foam mixed with an abrasive. In this type of polishing apparatus, each polishing disk 1 is pressed against both surfaces of the disk D and rotated to perform polishing. Polishing pad 3
is made of a mixture of urethane foam and abrasive, and its elastic properties allow the abrasive to come in even contact with the surface of the disk D with uniform pressure for polishing. It's getting old. By using a polishing pad 3 mixed with this type of resin, a device has been devised to realize an appropriate contact pressure of the polishing agent. This type of polishing apparatus is disclosed, for example, in Japanese Patent Application Laid-Open No. 183634/1983. However, even if such improvements are made to the polishing pad 3,
There is a limit to setting the contact pressure of the polishing agent against the disk D with high precision, and there is also the problem that the polishing pad 3 wears out as the polishing work progresses. Furthermore, it is necessary to clean the polishing debris after the polishing operation has progressed, but this requires equipment such as a nozzle, which also has the drawback of complicating the apparatus.

Therefore, it is conceivable to polish this type of disk D using a magnetic polishing device. In a magnetic polishing device, the strength of the magnetic field orients the abrasive to form a uniform abrasive surface, making it easier to perform high-precision polishing work with appropriate pressure.

As an example of polishing a relatively large polishing surface such as a disk D using this magnetic polishing device, a rotating disk having magnetic poles is provided on a work table that supports the object to be polished, and the object is There is one in which a magnetic field is formed as a circuit that passes through the object to be polished, and a magnetic abrasive is oriented and interposed in the magnetic field between the rotary disk and the object to be polished, thereby forming a brush made of the abrasive. However, this type of magnetic polishing device has a structure in which the lines of magnetic force pass through the inside of the object to be polished, so it can only process objects to be polished that are magnetic, and has the drawback that it is difficult to polish disks made of aluminum or resin. .

FIG. 7 shows another conventional example of a magnetic polishing apparatus capable of polishing disks and the like. In this magnetic polishing device, a coil 7 is wound around an iron core 6 provided in a yoke 5, and an electromagnet is configured. York 5
Further, magnetic poles 8a and 8b are provided on the lower surface of the iron core 6, and both magnetic poles 8a and 8b are joined via a non-magnetic material 9. The portion where the non-magnetic material 9 is interposed faces the disk D, which is the object to be polished, on the work table 10. In this polishing apparatus, when the disk D is made of a magnetic material, lines of magnetic force coming out from one magnetic pole 8a pass through the disk D and return into the other magnetic pole 8b. If a magnetic abrasive is interposed between the magnetic poles 8a, 8b and the disk D, this abrasive is oriented by a magnetic field and formed into a brush shape. Magnetic poles 8a, 8b and work table 1
If 0 is moved relatively, the surface of the disk D will be polished by the abrasive brush.
Further, when the disk D, which is the object to be polished, is made of a non-magnetic material, the work table 10
A plate 11 made of a magnetic material is placed on top, and a disk D is placed on top of it. With this configuration, a magnetic circuit from the magnetic pole 8a passing through the magnetic plate 11 to the magnetic pole 8b is constructed, and by interposing the abrasive in this magnetic field, an abrasive brush can be constructed. Become. Therefore, it becomes possible to polish a non-magnetic object to be polished. This type of magnetic polishing apparatus is disclosed, for example, in Japanese Patent Laid-Open No. 1160/1983.

However, in such a magnetic polishing device,
There is a drawback that only one side of the disc-shaped object to be polished can be polished. Therefore, the polishing operation must be performed twice, on the front and back sides, and each time the magnetic field must be destroyed to recover the abrasive, and the abrasive must be supplied again to form the brush, making the setup complicated. There are drawbacks to it.

[Purpose of the invention]

The present invention has been made by focusing on the above-mentioned conventional problems, and it is possible to polish the back surface of a disc-shaped object to be polished simultaneously and evenly by applying uniform pressure.
Another object of the present invention is to provide a magnetic polishing apparatus which can polish objects having shapes other than discs, and which can also polish non-magnetic objects.

[Structure of the invention]

The magnetic polishing apparatus according to the present invention comprises a pair of disks that face each other in parallel and rotate in the same direction, one of which has an S magnetic pole and the other a N magnetic pole, and the two disks have magnetic polishing between them. A polishing brush is formed by an abrasive agent oriented in a magnetic field, and a disk-shaped object to be polished is held by a holding shaft arranged parallel to the rotation axis of the pair of disks. A disk-shaped object to be polished is inserted into the polishing brush in a position parallel to the disk, and the non-polishing object is rotationally driven in the same direction as the disk by the holding shaft.

Hereinafter, a detailed explanation will be given with reference to the drawings of FIGS. 1 to 3.

FIG. 1 is a front view showing a magnetic polishing apparatus according to the present invention, and FIG. 2 is a left side view thereof.

Reference numeral 21 in the figure is a rotating shaft. This rotating shaft 2
1 is supported by bearings 22a and 22b, and is rotationally driven by a drive source such as a motor. A pair of discs 23 are fixed to the rotating shaft 21 so as to face each other. This disk 23 is composed of a permanent magnet 24 such as a ferrite magnet, a soft iron disk 25 fixed to the opposing surface thereof, and further fins 26 fixed to the opposing surface. One of the opposing surfaces of the two disks 23 is the N pole,
The magnetic poles are configured such that the other is the south pole.
The fins 26 are made of a magnetic material, and as shown in FIG. 2, four fins 26 are fixedly arranged radially around the rotating shaft 21. The fins 26 are provided to partially increase the magnetic flux density.

Reference numeral 27 is a liquid injection pipe. This liquid injection pipe 27 is inserted into the center hole 21a of the rotating shaft. The tip of the liquid injection pipe 27 extends to the center of the opposing portions of the two discs 23. And it communicates with a liquid injection port 21b bored in the radial direction of the rotating shaft 21.

Reference numeral 28 is a holding shaft. This holding shaft 28 is rotatably supported by a bearing 29. Further, the holding shaft 28 is rotationally driven by a motor. A holder 28a using a nut or the like is provided at the tip of the holding shaft 28.
The object to be polished, such as the disk D, is held by the .

As shown in FIG.
and 33 are fixedly installed. The bearings 22a and 22b are held by one of the pillars 32, thereby supporting the rotating shaft 21. Also, the other support 33
A bearing 29 is held by the holding shaft 28, and the holding shaft 28 is supported by the bearing 29. Further, a cover support post 34 is fixed to the edge of the frame 31, and a cover 35 is fixed to the top of this support post 34, and a cover 36 is fixed to the bottom thereof.

The magnetic abrasive 40 is filled between the two disks 23 . The magnetic abrasive 40 is oriented by the magnetic field between the two permanent magnets 24, and an abrasive brush of the magnetic abrasive is formed between the two discs 23. On the other hand, the disk D, which is the object to be polished, is held by the holding shaft 2.
8 and inserted into the brush formed by the abrasive 40. The rotating shaft 21 and the holding shaft 28 are driven by the motor to rotate clockwise in FIG. 2, that is, in the same direction. Then, both sides of the disk D are simultaneously polished by the brush of the polishing agent 40. As shown in FIG. 2, since the disc 23 and the disc D rotate in the same direction, the relative speed between the disc D and the brush of the abrasive 40 can be increased. Further, in part A in FIG. 2, the angular velocity of the disk D is small, but the angular velocity of the brush of the abrasive 40 is correspondingly large. In the B section, on the other hand, the angular velocity of the disk D is large and the angular velocity of the brush is small. In this way, the speed differences between the radii of the rotating bodies are compensated for each other, so that each part can be polished under uniform conditions.

Further, when a liquid is injected into the liquid injection pipe 27 during the polishing operation, the liquid flows from the liquid injection port 21b toward the outer circumference inside the polishing slurry 40 due to rotational centrifugal force. This flow makes it possible to continuously discharge polishing debris from the disk D. When the disk D is made of a non-magnetic material, by discharging the polishing debris as a liquid, it is possible to prevent the polishing debris from interfering with the orientation of the polishing agent 40.

FIG. 3 is a front view showing a magnetic polishing device according to the present invention configured using a single magnet;
FIG. 4 is its left side view.

This magnetic polishing device has a centering sleeve 42 fixed at the center of a rotating shaft 21, and two discs 41 facing each other around the outer periphery of this sleeve 42.
is permanently installed. This disk 41 is made of a magnetic material such as soft iron. A permanent magnet 43 such as a ferrite magnet is fixed between both disks 41. Further, a non-magnetic cover 44 is provided on the surface of the permanent magnet 43. Also, both disks 4
A fin 45 is fixedly provided on the opposing surface of 1. This fin 45 is connected to the rotating shaft 21 as shown in FIG.
are arranged radially around the center.

The magnetic field lines emitted from the permanent magnet 43 are the disk 41
A closed-loop magnetic field is formed by passing through the fins 45, and both disks 41 have N and S magnetic poles. A magnetic abrasive 40 having magnetism is attached to both disks 4.
1, and is oriented by a magnetic field to form a brush of abrasive 40. Holding shaft 28
The disk D held in is inserted into the brush. Polishing is performed by the rotation of the brush and the rotation of the disk D.

Since the magnetic polishing apparatus shown in FIG. 3 uses only one permanent magnet 43 to form a closed loop magnetic field, it is possible to construct a simple and efficient apparatus.

In both the embodiments shown in FIGS. 1 and 3, a disk D is shown as the object to be polished, but it is also possible to polish a long object or the like. In this case, a long object to be polished is fed in a direction across the brush of the abrasive 40 and polished by the rotating abrasive brush. In particular, in the case of the configuration shown in FIG. 3, the area of the brush of the abrasive 40 becomes smaller as the permanent magnet 43 is closer to the rotating shaft 21, so that it can be used when polishing a long object to be polished. , is more suitable than the one in FIG.

Further, in each figure, the magnetic circuit is constituted by the permanent magnets 24 and 43, but it is also possible to use an electromagnet made of a coil. In this case, since the electromagnet rotates, a rotating electrical contact is used to energize the coil. Although it is better to use an electromagnet to obtain a larger magnetic force, the use of a permanent magnet has advantages such as being lighter and not having to worry about preventing the coil from generating heat. In addition, when a permanent magnet is used, the magnetic force that orients the abrasive 40 becomes slightly weaker, but when polishing a soft object such as an aluminum disk or a plastic disk, its polishing effect is can be fully demonstrated.

The magnetic polishing agent 40 used in the magnetic polishing apparatus according to the present invention may be the same as that used conventionally. However, in the present invention, a magnetic field is formed between opposing discs, and the abrasive 40 is filled between them to form a brush. Therefore, a magnetic abrasive suitable for this configuration has a uniform and fine particle size. The one is good. Also, those with low specific gravity are easier to handle in practical terms. Examples of the magnetic abrasive 40 include monoiron alumina, ferrite, or chromium dioxide. Among these magnetic abrasives, ferrite-based abrasives (such as barium ferrite) have plate-like particles and therefore have a low polishing rate, but are suitable for high-precision finishing. Furthermore, since chromium dioxide is acicular, it has good orientation in a magnetic field.

In practice, polishing oil and additives are added to the polishing agent to prevent seizure, prevent oxidation of the polishing surface, and prevent the polishing agent from scattering. As these, for example, higher fatty acids, metal soaps of higher fatty acids, higher fatty acid esters, mineral oils, silicone oils, etc., a combination thereof, or a dispersion of these in water can be used. Note that these liquids may be supplied from the liquid injection pipe 27 shown in FIG.

[Embodiments of the invention]

Next, specific embodiments of the present invention will be described.

Example 1 In the magnetic polishing apparatus shown in FIG. 1, a soft iron disk 2 with a diameter of 130 mm is attached to a ferrite magnet 24 with a diameter of 120 mm.
5 was fixed, and the interval between the disks 23 was set to 10 mm. Abrasive 40 is alumina-iron type (65% iron, average particle size
50μ, with approximately 3% stearin added) was used.

The object to be polished was a 5-inch aluminum magnetic disk substrate, and polishing was performed for 2 minutes at a rotational speed of 100 rpm (linear velocity at the outer periphery of the disk of 68 cm/sec).

The surface roughness of the polished surface before polishing was Rmax = 10 μm, but the surface roughness after polishing was Rmax = 0.3 μm at the outer circumference of the disk, and Rmax = 0.4 μm at the inner circumference.

Example 2 The same disk as that shown in Example 1 was used as the object to be polished, and the polishing work was performed using the same equipment conditions as in Example 1 and using chromium dioxide (added with 1% stearic acid) as the polishing agent. .

Polishing was performed for 4 minutes at a disk rotation speed of 120 rpm. As a result, the surface roughness after polishing is Rmax = 0.01μm at the outer periphery of the disk, and Rmax at the inner periphery.
= 0.01 μm.

Example 3 The apparatus conditions were the same as in Example 1, and barium ferrite was used as the polishing agent 40. Pure water containing 0.03% sodium laurate and 0.1% carboxymethylcellulose was poured into the liquid injection tube 27 shown in Figure 1 at 100%
While supplying at cc/min, the diameter of the polished object is
A 12 cm, 2 mm thick polycarbonate disk was polished for 6 minutes.

The surface roughness after polishing is
Rmax=0.04 μm, and Rmax=0.04 μm at the inner circumference.

〔Effect of the invention〕

As described above, according to the present invention, the following effects can be achieved.

(1) In the case of a disk-shaped object to be polished, the front and back surfaces can be polished simultaneously. As a result, polishing work can be done more efficiently.

(2) Since a magnetic field is created between opposing disks to form a polishing agent brush, it is possible to polish even objects made of non-magnetic materials.

(3) It is possible to polish not only disk-shaped objects but also long objects.

(4) Since the abrasive comes into contact with the object to be polished with uniform pressure, proper polishing work can be performed even on a wide polishing surface.

(5) A pair of disks with a polishing brush in the middle and a disk-shaped object to be polished are supported by mutually parallel shafts, and both are driven in the same direction. Since the polishing brush and the object to be polished are both rotationally driven in this manner, the relative speed between the polishing brush and the object to be polished can be increased, and high-speed polishing becomes possible. Furthermore, since the disc on which the polishing brush is formed and the object to be polished are driven in the same direction, the relative speed with respect to the polishing brush is approximately constant at each position in the radial direction of the object to be polished. This makes it possible to eliminate variations in polishing accuracy.

[Brief explanation of drawings]

Fig. 1 is a front view showing a magnetic polishing device according to the present invention, Fig. 2 is a left side view thereof, Fig. 3 is a front view of a magnetic polishing device having a structure different from that in Fig. 1, and Fig. 4 is its left side. 5 is a front view of a conventional disk polishing device, FIG. 6 is a side view thereof, and FIG. 7 is a sectional view showing a conventional magnetic polishing device for disks. 21...Rotating shaft, 23...Disc, 24...Permanent magnet,
25... Soft iron disc, 28... Holding shaft, 28a... Holder, 40... Abrasive, 41... Disc, 43... Permanent magnet, D... Disc.

Claims (1)

[Claims] 1. An abrasive having magnetism between a pair of disks facing in parallel and rotating in the same direction, with an S magnetic pole formed on one side and an N magnetic pole formed on the other side. is interposed, and this abrasive is oriented between both disks by a magnetic field between the two disks to form a polishing brush, and a disc-shaped An object to be polished is held, and this disk-shaped object to be polished is inserted into the polishing brush oriented between both disks in a posture parallel to the disk, and the object to be polished is held by the holding shaft. A magnetic polishing device in which an object is rotationally driven in the same direction as the rotation direction of both disks. 2. The magnetic polishing device according to claim 1, wherein the opposing disks are formed by a permanent magnet and a soft iron disk provided on the opposing surface thereof. 3. The magnetic polishing device according to claim 1, wherein the opposing disks are formed of soft iron disks, and a permanent magnet is interposed between the two disks at a portion near the rotation axis.