JPS60177870A - Magnetic polishing material - Google Patents

Abstract

PURPOSE:To improve the polishing efficiency and the accuracy of a polished surface by coating the surface of the individual particle of the ferromagnetic powder as basic core, with the grinding-grains such as fused alumina, silicon carbide as the conventional polishing material and the grinding-grains such as silica and garnet as natural polishing material, and preparing a polishing material through the joining of the above-described powder as basic core and ferromagnetic material. CONSTITUTION:The magnetic material such as iron powder and ferrochrome having a particle size of about 80-325 mesh is used as core material 1, and the minute polishing powder such as fused alumina is used as minute polishing powder 2, and sodium silicate, thermosetting phenol resin, etc. are used as binding agent 3, and these three components are sufficiently mixed, and heated if necessary, and a magnetic polishing material is formed. Through the above-described method, a variety of polishing material can be prepared in accordance with the working object, and the press-contact force of a polishing brush for a workpiece which is generated between N and S magnetic poles can be varied arbitrarily according to the magnitude of the particle size of the ferromagnetic material which forms the basic core. Since the rigidity of the polishing brush which is formed in the magnetic field is generally proportional to the square of the particle size of the ferromagnetic material which forms the basic core, the range of the working amount can be widened by adjusting the particle size of the ferromagnetic material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Object of the Invention) The present invention relates to a magnetic abrasive material, particularly to a magnetic abrasive material used in surface finishing or deburring using a magnetic field.

(Prior art) Conventionally, mechanical parts such as bearings, screws, clock frames, molds, etc. have been polished using manual polishing methods such as pub polishing, belt polishing, polishing, barrel polishing, and elastic grindstone polishing. Magnetic polishing is known as a relatively new technique, but it has the drawback of low polishing efficiency.

In addition, for magnetic polishing, for example, a ferromagnetic polishing material is inserted between opposing N-5 magnetic poles to form a so-called polishing plan.
It is known that the surface of the workpiece is polished by applying pressure to it. In this case, ferromagnetic materials such as ferrochrome, sendust, and cermet powder are used, but their polishing performance is low, and However, cermets also require a pulverization and classification process, and in particular, cermets require a firing process, which requires a great deal of time and labor, resulting in high manufacturing costs and labor costs.

(Objective of the Invention) The object of the present invention is to eliminate the inefficiency and high cost of the above-mentioned conventional methods, and to improve polishing surface accuracy and polishing direction, the core of the present invention is ferromagnetic powder, and a conventional polishing material such as fused aluminium is used as the core. Abrasive grains such as silicon carbide, boron carbide, boron nitride, synthetic diamond, etc. or abrasive grains of natural abrasive materials such as silica, garnet, etc. are coated on the surface of each particle of the core ferromagnetic powder, and the ferromagnetic An object of the present invention is to provide a magnetic abrasive material that is firmly bonded to the body.

(Structure of the Invention) The magnetic abrasive material of the present invention is a magnetic abrasive material in which the core material is ferromagnetic fine powder, and the abrasive fine powder is fixed around the core material by a binder. Its mode is schematically shown in FIG. This is the general rule shown in .

The core material 1 may be made of iron powder, sendust, ferrochrome, cermet, etc., but is not limited to the above-mentioned materials as long as it is a magnetic material. The particle size of the core material is suitably in the range of 80 to 325 mesh. Coarse particles of 80 mesh or more, fine particles of 325 mesh or less will affect the porosity of the particles in the magnetic field and the brush-like particle distribution state in the magnetic field. This should be avoided as much as possible since it causes a decrease in polishing efficiency. The shape of the core material particles may be spherical or polygonal depending on the type and material of the material to be polished.

As polishing fine powder, fused alumina (quality) and silicon carbide (quality) are used.
Synthetic abrasive grains such as , boron carbide, boron nitride, and synthetic diamond, and natural abrasive grains such as silica, garnet, and emery are suitable.

The binder 3 that binds the core material and the abrasive fine powder 2 includes inorganic substances such as silicic acid, organic substances such as thermosetting phenol resin, unsaturated polyester, epoxy resin, thermoplastic I-lyethylene, and the like. used.

A method for producing the magnetic abrasive of the present invention using the above-mentioned core material, abrasive fine powder, and binder will be described below.

First, a core material such as reduced iron powder is mixed with a binder such as a thermosetting phenol resin and thoroughly kneaded, and then an abrasive material such as alumina powder is added and mixing is continued. Add this and continue until the three ingredients are thoroughly mixed, and add the missing amount of the three ingredients as necessary. In this way, a magnetic abrasive of the present invention is obtained in which the core material is coated and fixed with abrasive fine powder as shown in FIG.

The desirable mixing ratio range for the champion is as follows.

Core material 100% by weight Fine powder 15-20 Binder 5-7 150-180°C, 20-20°C as necessary during the above kneading
By heating the kneaded material for 40 minutes and hardening the abrasive, the nine magnetic abrasives were sufficiently finished. Heat kneading is particularly effective when a thermosetting resin is used as a binder.

As mentioned above, this magnetic abrasive material has a core of ferromagnetic material, and its surface is coated with an abrasive material, and the two are firmly bonded by a binder, so there is flexibility in selecting the type and particle size of the abrasive material according to the processing purpose. Not only is it extremely wide, but it also makes it possible to arbitrarily change the pressing force of the polishing brush against the workpiece, which is generated between the two pN-8 magnetic poles, depending on the particle size of the core ferromagnetic material. Even when the grain size of the coated abrasive is constant, the stiffness of the polishing brush generated in the magnetic field can be adjusted by the grain size of the core ferromagnetic material, and the larger the grain size of the ferromagnetic material, the more The amount of processing can be increased. In general, the stiffness of the polishing brush that occurs in the magnetic field is proportional to the square of the grain size of the core ferromagnetic material, so by adjusting the grain size of the ferromagnetic material, the possible range of processing amount can be widened. This can be said to be a characteristic of abrasive materials.

Comparing the magnetic properties of this magnetic abrasive with conventionally commonly used sendust and ferrochrome, the magnetic flux density for the same excitation current and the pull-out resistance of the polished object in the magnetic field (direction perpendicular to the magnetic field direction) are as shown in Table 1. It has been demonstrated that this magnetic abrasive exhibits approximately three times the magnetic flux density and pull-out resistance of ferrochrome in the practical range (excitation current -1.0 to 3.0 amperes), and is superior to the magnetic flux density and pull-out resistance of Sendust. Ta.

(Table 1) Comparison of magnetic flux density and withdrawal resistance Upper row B - Magnetic flux density (Te5la) Lower row F - Withdrawal resistance [kg] The magnetic permeability (magnetic induction/magnetic field strength) of this magnetic abrasive material is as shown in Table 2. Is it almost comparable to Sendust?
We obtained better results than this.

(Table 2) Comparison of magnetic permeability - As shown in Table 3, the present magnetic abrasive achieved much better results than Sendust and Ferrochrome in terms of the amount of processing in a given period of time.

(Table 3) Comparison of machining amount (A: pure aluminum material, B: 5US304 stainless steel material. Machining time: 3 minutes) Regarding the surface roughness of the polished material, the finish using this magnetic abrasive is better than that of conventional sendust and ferrochrome. It was found that this method was much better than the case of using the method.

Example 1 Reduced iron powder (manufactured by Hakuhan Metal Foil Powder Co., Ltd., particle size 80-120 mesh, sea 0.8% by weight, 120-145 mesh 176% by weight, 145-200 mesh 33.0% as core material)
Weight %, 200-250 mesh 17.6 weight %, 25
0 to 350 mesh 108% by weight, 350 mesh 1/2
02 weight section) 1 kg, alumina powder (JIS standard WA + 2000 manufactured by Showa Light Metal @) 80, resol type phenolic resin (BRL manufactured by Showa Union Gosei Co., Ltd.)
-20'7) 30g was thoroughly mixed, and the same alumina 110y- and phenolic resin 35y- as above were again added to this mixture, the whole was thoroughly kneaded, and the mixture was heated at 170°C for 1.30 minutes. The magnetic abrasive material of the present invention was manufactured by curing. The wood was a magnetic abrasive with an irregular shape.

The relationship between the magnetic flux density, drawing resistance, and excitation current of this magnetic abrasive material was as shown in FIG. 2, and the results were almost the same as those shown in Table 1 above. Also, the magnetic permeability is 1
．． It was 51 μsg.

Using wood, pure aluminum material and 5US304 stainless steel material (both round bar shapes) were rotated at 180 O.
As a result of rotating at r, p, m, and machining and polishing for 3 minutes in a magnetic field with an excitation current of 0.6A, the machining amount was 26.
It was 0 to 48 ■.

In machining tests carried out using Sendust and Ferrochrome under the same conditions, the machining amounts for Sendust were 08 to 1.2W and 1.2W, respectively.

0.3 my and 0.3 my in ferrochrome, respectively.
It merely marked four capes. This clearly shows the outstanding amount of wood processing.

Further, as a result of measuring the roughness of the surface of the material to be polished obtained in the above processing, a surface roughness as shown in FIG. 3 was obtained (shown by unevenness in cross section). According to this, it is clear that the smoothness of the polished surface obtained by using wood is significantly superior to that obtained by using conventional sendust and ferrochrome.

Example 2 Alumina powder (JI
S standard WA≠6000F, ) 190 Y-1 thermosetting epoxy resin 55? were mixed and cured at 180° C. for 40 minutes to obtain the present magnetic abrasive material.

Figure 4 was obtained as a result of measuring the changes in magnetic flux density and pulling resistance of wood due to excitation current. The results of Sendust and Ferrochrome are included for comparison, but the superiority of this month's magnetism is clear. The magnetic permeability was 1.50 μsg, which was almost the same as Sendust.

Pure aluminum and 18-8 stainless steel were processed using wood under the same conditions as in Example 1, and the processed amounts were 27.5 mF and 5.0 In?, respectively. Met. In the case of Sendust under the same conditions, each is 0.9
my and 1.7 mW, and only 0.3 mg and 0.35 ■ were obtained for ferrochrome, respectively.

Roughness of the surface of the polished material The smoothness of the polished surface shown in FIG. 5 was significantly improved compared to conventional sendust and ferrochrome.

[Brief explanation of drawings]

Figure 1 shows a model of the magnetic abrasive particles of the present invention, and Figure 2 shows wood (
Figure 3 is a diagram of the relationship between magnetic flux density, pull-out resistance, and excitation current in Example 1), Figure 3 is a diagram of the surface roughness of the material to be polished in Example work,
The figure is a diagram showing the relationship between magnetic flux density, extraction resistance, and excitation current of wood (Example 2), and FIG. 5 is a diagram showing the surface roughness of the material to be polished in Example 2. 1. Core material, 2. Fine abrasive powder, 3. Binder Patent applicant Showa Denko Co., Ltd. Toyo Abrasive Industry Co., Ltd. Representative patent attorney Sei Kikuchi - Figure 1 Atsushi 1a line Figure 3 5 US304 Processing Post-processing 5US304-1~-111\-2 Figure 4

Claims (1)

[Claims] A magnetic abrasive material made by using a ferromagnetic material as a core material and surrounding it with fine abrasive powder fixed by a binder.