JPH0550377A - Magnetogrinding method - Google Patents

Abstract

PURPOSE:To miniaturize a gringing attachment as well as to automate a grinding process by applying an abrasive grain, hardened with oil wax or the like, on a workpiece surface, and filling up a ferromagnetic grain in a gap between a permanent magnet and a workpiece, separately from the abrasive grain, in a magnetogrinding method by means of a numerically controlled machine tool. CONSTITUTION:An abrasive grain 6 covered with paraffin wax 7 is applied to the circumference of a cylindrical workpiece 2. In addition, a ferromagnetic grain 3 of about 100mum-500mum in ferrite grain size is filled up in a gap between a permanent magnet 1 and the workpiece 2. Then, the workpiece 2 is rotated and rocked in the axial direction, thus it is ground by means of magnetogrinding. With this constitution, paraffin is melted by frictional heating, and the abrasive grain 6 is stuck to an outer circumferential part of the ferromagnetic grain 3, through which a surface of the workpiece 2 is ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to attach a magnetic polishing tool to an NC machine tool or the like instead of a cutting tool to finish a die or the like after shape forming processing such as cutting, automatic polishing, metal or ceramics. It is used for mirror polishing of products such as, polishing for removal of work-affected layer, etc.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
Magnetic abrasive grains in which the abrasive grains 5 and the ferromagnetic material particles 4 are integrated with each other by adhering the abrasive grains 5 of aluminum oxide or the like of several μm in a metal-bonded state to the surface of the ferromagnetic material particles 4 of It was.

[0003]

As in the prior art, the magnetic polishing abrasive grains in which the polishing abrasive grains 5 are bonded to the surface of the ferromagnetic material particles 4 with a certain thickness are provided by the magnetic polishing apparatus shown in FIG. As shown in a partially enlarged view of the periphery of the object to be polished shown in FIG. 3, when the permanent magnet 1 and the object to be polished 2 are packed, the aluminum oxide on the surface is not a ferromagnetic material, so that the magnetic permeability is several hundreds of iron.
It is as small as 1/0, and the magnetic resistance as a magnetic circuit becomes very large. Therefore, the strength of the magnetic field generated in the magnetic circuit is small, and when the thickness of the polishing abrasive grain layer 5 such as aluminum oxide on the surface varies, the strength of the magnetic field weakens in inverse proportion to the thickness. It is very difficult to control the amount of polishing, and the permanent magnet requires a strong and very large object to generate a necessary magnetic field, which causes a problem that the device becomes large. Further, in the case of the same apparatus, there is a problem that the polishing time is several tens of times longer.

[0004]

In order to solve the above-mentioned problems, the magnetic polishing method of the present invention is a polishing abrasive grain hardened with a permanent magnet, ferromagnetic particles, oily wax or the like facing an object to be polished. In the magnetic polishing method in which the object to be polished and the permanent magnet are relatively rotated or oscillated, the polishing abrasive particles applied to the object to be polished or mixed with the ferromagnetic particles and the oily wax, Filled with a separate body from the ferromagnetic particles,
Alternatively, it is characterized by being replenished.

[0005]

As described above, in place of the magnetic polishing abrasive grains covered with the non-ferromagnetic polishing abrasive grains 5, the ferromagnetic particles and the particles having polishing ability are separated and held by oil wax or the like. According to, iron or nickel-based ferromagnetic particles 3
Since the two are in contact with each other, the abrasive grains 5 made of a non-magnetic material such as aluminum oxide do not intervene, and the strength of the magnetic field generated in the magnetic circuit can be increased from several times to several tens of times of the conventional one. ..

Below, the magnitude of the magnetic resistance acting on the magnetic circuit is determined only by the conventional magnetic abrasive material in which the outer peripheral portion of the magnetic material is covered with non-magnetic abrasive grains 5 and the ferromagnetic particles 3 of the present invention. The difference in the strength of the magnetic field acting on the magnetic circuit will be explained by comparing the cases.

Assuming that the magnetic abrasives 4 are arranged in a line between the permanent magnet 1 and the object to be polished 2 as shown in FIG. 7, the particle size of the magnetic abrasives 4 is assumed to be a cube, and one side of the magnetic abrasive 4 is assumed. Length
a, the thickness of the abrasive grains 5 is b, the permanent magnet 1 and the object to be polished 2
If the gap G is G, the magnetic abrasives 4 are arranged in series in the gap G by G / a. Since the abrasive grains 5 are not a ferromagnetic substance, they have a low magnetic permeability and can be considered as voids.

Let Lb be the total length of the polishing abrasive grains in the direction 12 in which the magnetic flux flows. Lb = 2b · G / a On the other hand, the total length La of the ferromagnetic material portion 4 is La = (a -2b) · G / a, the magnetic permeability of the ferromagnetic particles 4 is μa, the magnetic permeability of the non-magnetic abrasive grains 5 is μb, and the cross-sectional area perpendicular to the magnetic field of the ferromagnetic particles 4 is S = a. ^{When set to 2} , the magnetic permeability of non-magnetic material μb
Is about μb = μa / 1000, the magnetic resistance R between G is R = La / μa · S + Lb / μb · S = (a + 1998b) · G / μa · a ³ . Since a = 200 μm and b = 5 μm, the size of 1998b is about 50 times that of a in the above formula (), which is about 50 times as large as that of non-magnetic abrasive grains such as aluminum oxide, which is a magnetic abrasive that affects the magnetic resistance. It can be seen that the factor of 5 is very large. That is, when the magnetic polishing material 4 whose surface is covered with the non-magnetic polishing abrasive grains 5 such as aluminum oxide is used for the magnetic polishing, and when the ferromagnetic particles 3 and the polishing abrasive grains 6 are separated, they occur in the magnetic circuit. It can be seen that the magnetic field strength is several tens of times different.

[0009]

Embodiments will be described below based on embodiments.

In FIG. 3, abrasive grains 6 covered with paraffin wax 7 are applied to the periphery of a cylindrical object 2 to be polished, and ferromagnetic particles 3 made of ferrite and having a particle size of 100 μm to 500 μm are permanently applied. This is a magnetic polishing method in which the magnet 1 and the object to be polished 2 are filled in a gap of 3 mm and the object to be polished 2 is rotated and swung in the axial direction.

In this case, at first, the abrasive grains 6 and the paraffin wax 7 cover only the object to be polished 2 and are not polished at all, but the paraffin is generated by the frictional heat generated by the rotation and swing of the object 2 to be polished. Melts and the abrasive grains 6 adhere to the outer periphery of the ferromagnetic particles 3 to start polishing the surface of the object to be polished 2. The stress of the abrasive grains 6 pressed against the object to be polished 2 is
In proportion to the strength of the magnetic field generated in the magnetic circuit, a force of several tens of times is generated as compared with the case of using the conventional magnetic polishing material 4 whose surface is covered with polishing abrasive grains 5, and the polishing power is dramatically increased. Increase.

Similarly, FIG. 4 shows a mixture of a paraffin wax 7, a polishing abrasive grain 6 having a particle diameter of 5 μm to 10 μm, and a ferromagnetic particle 3 having a particle diameter of 100 μm to 500 μm. In this example, the material is filled in the gap between the permanent magnet 1 and the object to be polished 2 and the object to be polished 2 is swung and rotated. Also in this case, because the paraffin wax 7 is melted by frictional heat, the ferromagnetic particles 3 are closely arranged in series without forming a gap between the permanent magnet 1 and the object 2 to be polished, which is very important in the magnetic circuit. A large magnetic field is generated, and the same effect as the example of FIG. 3 is obtained.

FIG. 5 shows the surface of the object to be polished 8 having irregularities,
The abrasive grains 6 hardened with a paraffin wax 7 are applied in advance, and a magnetic field is applied between the rotating and oscillating permanent magnet 9 and the uneven object 8 to be polished, and a gap of 5 mm is 100 μm to 500 μm. This is an example in which the ferromagnetic particles 3 having a particle size of 1 are filled and the object 8 having irregularities such as a mold is polished. In this case, after making a shape with an NC milling machine, etc., using the same processing machine, replace the end mill at the tip with a permanent magnet for magnetic polishing, and then perform die polishing with the same NC software. I can. Also, depending on the finishing level, the type of abrasive material can be changed from one with grinding power to one with a slightly lower grinding power but with a mirror-like finish, which allows continuous mirror finishing with the same processing machine. became.

FIG. 6 shows a plate-shaped object 10 to be polished, to which abrasive grains 6 hardened with paraffin wax 7 have been applied in advance.
Between the two facing permanent magnets 1 with a left-right equidistant gap of 1 mm to 3 mm set, and the gap is filled with ferromagnetic particles 3 having a particle diameter of 200 μm to 300 μm. This is an example in which the flat object 10 to be polished is slid vertically and horizontally between 1 and 1, and is polished. Also in this case, similar to the above-mentioned example, it is possible to select the polishing abrasive grains according to the polishing level.

[0015]

As can be seen from the above embodiments, according to the present invention, since the magnetic circuit of the magnetic polishing apparatus is entirely made of a ferromagnetic material, the magnetic field generated in the magnetic circuit is equal to that of the conventional one.
The size was doubled and the polishing machine was downsized. Further, conventionally it was difficult to control the amount of polishing due to the variation in the thickness of the polishing abrasive grain layer, it was difficult to perform uniform polishing, the present invention, by making the ferromagnetic particles and polishing abrasive grains separate, Since the magnetic field generated in the magnetic circuit is stable, control is easy and uniform polishing is possible. Further, even if the gap between the permanent magnet and the object to be polished is large, the magnetic field generated in the magnetic circuit does not change as much as in the conventional case, so that even with the object having irregularities, a uniform polished surface can be obtained. Further, since the ferromagnetic particles and the abrasive grains are separated, conventionally, when the polishing ability deteriorated with the passage of time, it was necessary to replace all the magnetic abrasives. According to this, since the polishing abrasive grains mixed with wax or only the polishing abrasive grains can be replenished during the processing, the polishing amount does not decrease with the passage of time, and moreover, the workpiece to be polished from cutting processing to polishing Since it can be done without attaching and detaching from the machine, the processing time was shortened. As described above, the present invention has excellent effects.

[Brief description of drawings]

FIG. 1 is an overall side view of a typical apparatus for a magnetic polishing method of the present invention.

FIG. 2 is a cross-sectional view of magnetic abrasive particles used in a conventional magnetic polishing method.

3 is an enlarged side view of a polishing portion of the apparatus shown in FIG. 1 of the magnetic polishing method of the present invention, showing a case where polishing abrasive grains hardened with wax are applied to an object to be polished.

FIG. 4 is a partially enlarged perspective view of a magnetic polishing method of the present invention in which ferromagnetic particles are mixed with wax and abrasive grains to polish a cylinder.

FIG. 5 shows a mold or the like having irregularities by the magnetic polishing method of the present invention,
FIG. 4 is a partially enlarged perspective view of applying abrasive grains hardened with wax and polishing with ferromagnetic particles.

FIG. 6 is a partially enlarged perspective view of flat plate double-side polishing in the magnetic polishing method of the present invention.

FIG. 7 is a partially enlarged cross-sectional view of a conventional method for explaining the strength of a magnetic field of the magnetic polishing method of the present invention between a permanent magnet and an object to be polished.

[Explanation of symbols]

 1. Permanent magnet 2. Cylindrical object to be polished 3. Ferromagnetic particles such as ferrite or permalloy 4. 4. Ferromagnetic particles of magnetic abrasives 5. Abrasive grains that are metal-bonded with ferromagnetic particles. Abrasive grain 7. Oily or paraffin wax 8. Object to be polished 9. Rotating permanent magnet 10. Flat object to be polished 11. Rotation or swing direction of the object to be polished 12. Direction of magnetic field a. Particle size of magnetic abrasive b. Grain size of abrasive grains G. Gap between permanent magnet and object to be polished

Claims (3)

[Claims] 1. A magnetic field comprising a permanent magnet facing an object to be polished, ferromagnetic particles, abrasive grains hardened with oily wax, etc., for rotating or rocking the object to be polished and the permanent magnet relatively. In the polishing method, polishing abrasive particles hardened with an oily wax or the like are applied to the surface of the object to be polished, and the ferromagnetic particles are separate from the abrasive particles and are filled in the gap between the permanent magnet and the object to be polished. And magnetic polishing method. 2. In the magnetic polishing method, the ferromagnetic particles according to claim 1 and the abrasive grains are separately mixed with oil wax or the like, and the mixture is filled in the gap between the permanent magnet and the object to be polished. The magnetic polishing method according to claim 1, which is characterized in that: 3. In the above magnetic polishing method, the polishing abrasive grains according to claim 1 or the polishing abrasive grains hardened with oily wax or the like during the polishing or the initial stage of polishing according to claim 1 or a permanent magnet and an object to be polished. The magnetic polishing method according to claim 1, wherein the magnetic polishing is replenished in a gap between