JP2007210073A - Magnetic grinding device and magnetic grinding tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic grinding device which can efficiently grind even a workpiece formed of a magnetic metal, and also to provide a magnetic grinding tool. <P>SOLUTION: The magnetic grinding device is formed of the magnetic grinding tool 10 having a tip structure in which two or more permanent magnets 11a, 11b for magnetically attracting magnetic grains 2 are secured to a yoke 12 separately from each other, and after the magnetic grains 2 are magnetically attracted by the tip of the magnetic grinding tool 10, the magnetic grinding tool 10 is relatively moved on the workpiece 3 while being kept rotated or pivoted, to thereby carry out grinding of the workpiece 3. Herein the two or more permanent magnets 11a, 11b serve as a north pole and a south pole, respectively, and a closed magnetic circuit 4 is formed among the north pole 11a, the yoke 12, the south pole 11b, and the magnetic grains 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic polishing apparatus and a magnetic polishing processing tool, and more particularly to a magnetic polishing apparatus and a magnetic polishing processing tool that can efficiently polish a workpiece made of a magnetic metal material.

  For example, when a curved surface of a mold is precisely polished, many of them are performed manually. Therefore, there is a demand for a new technique that can be precisely polished and finished efficiently by mechanical means.

By the way, “a magnetically assisted processing method (also referred to as magnetic polishing method)”, which is a precision processing technology that incorporates the action of a magnetic field, has attracted attention as a new technology that is not bound by existing concepts. This magnetic polishing method realizes precise surface processing by applying a processing force and a kinetic force to magnetic abrasive grains or magnetic particles through the lines of magnetic force. In particular, if magnetic abrasive grains or magnetic particles are used as a particle brush, the particle brush exhibits a flexible processing behavior. For example, it is possible to perform precision polishing while maintaining the shape accuracy of complicated parts such as curved surfaces of molds. (For example, refer to Patent Document 1).
JP 2002-192453 A

  When the workpiece to be polished is made of a non-magnetic metal material, the magnetic polishing method generates a strong magnetic field in the processing area, and a particle brush made of magnetic abrasive grains or the like between the magnetic pole and the workpiece. By forming, the workpiece surface can be efficiently polished. However, when magnetically polishing a workpiece made of a magnetic metal material, such as a mold, unlike the case of magnetically polishing a workpiece made of a nonmagnetic metal material, it is formed between the magnetic pole and the workpiece. There is a problem that twisting phenomenon and stirring phenomenon occur in the middle of the particle brush, and the magnetic abrasive grains constituting the particle brush are pulverized and refined, and stable polishing cannot be performed over time. In addition, many magnetic abrasive grains remain on the surface of the workpiece after polishing, and a reduction in the number of abrasive grains used for polishing is a problem.

  This problem will be described in detail. FIG. 10 is a schematic view showing an example of a planar magnetic polishing apparatus provided with a conventional magnetic polishing processing tool. The illustrated magnetic polishing apparatus is an apparatus for magnetically attaching a workpiece made of a magnetic metal material to a magnetic table on a lower yoke, and polishing the workpiece using a magnetic polishing processing tool and magnetic abrasive grains. . The magnetic polishing tool is provided at the tip of a rotating shaft disposed above the workpiece to form a rotating magnetic pole, and the upper yoke is in contact with the rotating magnetic pole. An electromagnetic coil in which a coil is wound around an iron core is arranged between the upper yoke and the lower yoke. The magnetic field generated by the electromagnetic coil constitutes a closed magnetic circuit comprising iron core / upper yoke / rotating magnetic pole / workpiece / magnetic table / lower yoke / iron core. In such a conventional planar magnetic polishing apparatus, the magnetic abrasive grains in the processing region receive a strong magnetic force and are concentrated and filled between the rotating magnetic pole and the workpiece. At this time, when the rotating magnetic pole is rotated at a high speed, the magnetic abrasive grains also rotate following the rotation, and the surface of the workpiece is polished.

  In the magnetic polishing apparatus shown in FIG. 10, since a workpiece made of a magnetic metal material is always magnetized to the south pole, a strong magnetic attractive force acts on the magnetic abrasive grains contacting the surface of the workpiece. At this time, the magnetic abrasive grains on the rotating magnetic pole side constituting the particle brush rotate together with the rotating magnetic poles, whereas the magnetic abrasive grains on the workpiece side constituting the particle brush are magnetically attracted to the magnetized workpiece surface. Thus, it becomes difficult to follow the rotation of the rotating magnetic pole. As a result, a twisting phenomenon and a stirring phenomenon occur in the middle of the particle brush, so that the magnetic abrasive grains are pulverized and refined, and the magnetic abrasive grains remain on the surface of the workpiece.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a magnetic polishing apparatus and a magnetic polishing processing tool capable of efficiently polishing a workpiece made of a magnetic metal material. Is to provide.

  A magnetic polishing apparatus according to the present invention for solving the above-described problems includes a magnetic polishing processing tool having a tip structure in which two or more permanent magnets that magnetically attract magnetic abrasive grains are fixedly spaced from a yoke. The magnetic abrasive grains are magnetically attracted to the tip of the magnetic polishing tool, and then the workpiece is polished by rotating relative to the workpiece while rotating or rotating. In the present invention, each of the two or more permanent magnets is an N pole or an S pole, and a closed magnetic circuit is configured between the N pole, the yoke, the S pole, and the magnetic abrasive grains.

  In order to solve the above problems, a magnetic polishing tool of the present invention has a tip structure in which two or more permanent magnets for magnetically adsorbing magnetic abrasive grains are fixedly spaced from a yoke, and a magnetic abrasive at the tip. It is a tool for polishing a workpiece by moving the workpiece relative to the workpiece while rotating or rotating the particles after magnetically adsorbing the particles.

  In the present invention, when a workpiece made of a magnetic metal material that is easily magnetized is processed, the magnetic phenomenon in which the magnetic abrasive grains are magnetically attracted to the workpiece can be weakened to perform efficient polishing. The apparatus and tool are provided, and as specific means, (1) the influence of the magnetic field on the surface of the workpiece is reduced by configuring a new closed magnetic circuit that is not a conventional closed magnetic circuit; (2) The polishing process is performed while demagnetizing the workpiece using the loop damping demagnetization principle. According to the present invention, since each of the two or more permanent magnets is fixed apart from the yoke, the magnetic abrasive grains are magnetically attracted (hereinafter referred to as “magnetic The particle brush is formed. Such a particle brush forms a closed magnetic circuit between the permanent magnet and the yoke, and the magnetic abrasive grains are held by the magnetic lines of force of the closed magnetic circuit. As a result, at the time of relative movement, both the magnetic abrasive grains on the polishing tool side and the magnetic abrasive grains on the workpiece side can move following the relative movement. According to such a magnetic polishing apparatus of the present invention, even when a workpiece made of a magnetic metal material is to be processed, the conventional twisting phenomenon and stirring phenomenon are unlikely to occur. It is possible to suppress the progress of conversion.

  Furthermore, according to the present invention, after the magnetic abrasive grains are magnetically attracted to the tip of the magnetic polishing tool, the workpiece is polished by being relatively moved on the workpiece while being rotated or rotated. Different magnetic poles pass repeatedly over the magnetized workpiece. As a result, it is possible to perform polishing while demagnetizing the magnetized workpiece by the loop damping demagnetization principle. Since the magnetization of the workpiece made of a magnetic metal material is weakened, the number of magnetic abrasive grains remaining in the state of being magnetically attached to the surface of the workpiece can be reduced, and polishing is performed while holding the magnetic abrasive grains used for polishing between the magnetic poles. Processing can be performed efficiently.

  According to the magnetic polishing apparatus and the magnetic polishing processing tool of the present invention, even when a workpiece made of a magnetic metal material is processed, the conventional twisting phenomenon and stirring phenomenon are unlikely to occur. Since the progress of pulverization and fine graining can be suppressed, polishing can be performed efficiently. Further, according to the present invention, the polishing can be performed while demagnetizing the workpiece using the loop damping demagnetization principle, so that the magnetic abrasive grains remaining in the state of being magnetized on the surface of the workpiece are reduced. In addition, the magnetic abrasive grains used for polishing can be held between the magnetic poles and polishing can be performed efficiently.

  Hereinafter, a magnetic polishing apparatus and a magnetic polishing tool of the present invention will be described with reference to the drawings. In addition, this invention includes the range which has the technical feature, and is not limited to drawing shown below.

  In the present invention, when a workpiece made of a magnetic metal material that is easily magnetized is processed, the magnetic phenomenon in which the magnetic abrasive grains are magnetically attracted to the workpiece can be weakened to perform efficient polishing. As a specific means, (1) a new closed magnetic circuit that is not a conventional closed magnetic circuit is configured to reduce the influence of the magnetic field on the surface of the workpiece. ) Polishing is performed while demagnetizing the workpiece using the loop damping demagnetization principle.

  FIG. 1 is a configuration diagram showing an example of a magnetic polishing apparatus of the present invention, and FIG. 2 is a drawing-substituting photograph showing an example of a magnetic polishing processing tool used in the magnetic polishing apparatus of the present invention. As shown in FIGS. 1 and 2, the magnetic polishing apparatus 1 of the present invention has a tip structure in which two or more permanent magnets 11 that magnetically adsorb magnetic abrasive grains 2 are fixed to a yoke 12 separately from each other. A machining tool 10 is provided. Then, after the magnetic abrasive grains 2 are magnetically attracted to the tip of the magnetic polishing tool 10, the workpiece 3 is polished by rotating relative to the workpiece 3 while rotating or rotating. At this time, each of the two or more permanent magnets 11 is an N pole or an S pole, and the closed magnetic circuit 4 is configured among the N pole 11a, the yoke 12, the S pole 11b, and the magnetic abrasive grains 2.

  As shown in FIGS. 1 and 2, the magnetic polishing tool 10 has a tip structure in which two or more permanent magnets 11 that magnetically adsorb magnetic abrasive grains 2 are fixed to a yoke 12 apart from each other. This is a tool for polishing the workpiece 3 by causing the magnetic abrasive grains 2 to be magnetically attracted to the tip and then rotating or rotating the workpiece to move the workpiece 3 relatively. When the magnetic abrasive grains 2 are magnetically attached to the magnetic polishing tool 10, as shown in FIGS. 1 and 2, the magnetic abrasive grains 2 are magnetically attached to the separated permanent magnets 11 to form a particle brush 2 ′. The closed magnetic circuit 4 is formed by the particle brush 2 ′, the permanent magnets 11, 11 and the yoke 12. The present invention can reduce the influence of the magnetic field on the surface of the workpiece 3 made of a magnetic metal material by the closed magnetic circuit 4 formed by magnetically attaching the magnetic abrasive grains 2 to the magnetic polishing tool 10. . Reference numeral 13 in FIGS. 1 and 2 denotes a fixing jig, which joins a tip portion made of a yoke and a permanent magnet. The fixing jig 13 is attached to a chuck portion of a rotating device, a rotating device, or a reciprocating device.

  FIG. 3 is a drawing-substituting photograph showing a specific form in which the magnetic polishing apparatus of the present invention polishes a workpiece, and FIG. 4 shows a specific form of the entire configuration of the magnetic polishing apparatus shown in FIG. It is a drawing substitute photograph. The illustrated example shows a test configuration, and the magnetic polishing apparatus 1 of the present invention is not limited to the illustrated form. As shown in FIG. 3, the magnetic polishing tool 10 is attached to a rotating device, and magnetic abrasive grains 2 are magnetically attached to a permanent magnet 11 at the tip thereof to form a particle brush 2 '. In the magnetic polishing apparatus shown in FIG. 3, the distance between the magnetic polishing tool 10 and the workpiece 3 is adjusted, and the particle brush 2 'is in contact with the surface of the workpiece 3 made of a magnetic metal material. When the magnetic polishing tool 10 is rotated in this state, the surface of the workpiece 3 is polished by the particle brush 2 '. As shown in FIG. 4, the workpiece 3 is fixed to an XY stage that is a moving table 14, and moves relative to the magnetic polishing tool 10 by moving the XY stage.

  According to the present invention, since each of the two or more permanent magnets 11 is fixed to the yoke 12 so as to be spaced apart, the magnetic abrasive grains 2 are magnetized on the surfaces of the plurality of permanent magnets 11 that become the north pole 11a and the south pole 11b, respectively. The particle brush 2 'is formed by wearing. Such a particle brush 2 ′ forms a closed magnetic circuit 4 between the permanent magnet 11 and the yoke 12, and the magnetic abrasive grains 2 are held by the magnetic lines of force of the closed magnetic circuit 4. As a result, at the time of relative movement, both the magnetic abrasive grains on the polishing tool side and the magnetic abrasive grains on the workpiece side can move following the relative movement. According to the magnetic polishing apparatus of the present invention, when a workpiece 3 made of a magnetic metal material is processed, the conventional twisting phenomenon and stirring phenomenon hardly occur, and the magnetic abrasive grains are pulverized and finely divided. You can keep going.

  Next, the demagnetization of the workpiece using the loop damping demagnetization principle will be described. When the particle brush 2 ′ at the tip of the magnetic polishing tool 10 is brought into contact with the surface of the workpiece made of a magnetic metal material and the magnetic polishing tool 10 is rotated, at any one point on the workpiece surface, N The alternating magnetic field acts by alternately passing the poles and the S poles. Due to this action, the magnitude of the magnetization of the workpiece made of the magnetic metal material gradually becomes a small value as the tool 10 rotates and enters a demagnetized state. FIG. 5 is a principle diagram of the loop attenuation demagnetization method. As shown in FIG. 5, a magnetic material having a certain residual magnetic flux density Br is gradually attenuated in the order of 1 ′ → 2 ′ → 3 ′ → 4 ′ → 5 ′ while alternately applying a plus / minus magnetic field H. As the time t elapses, the residual magnetic flux density of the magnetic material approaches the origin 0 while decreasing in the order of 1 → 2 → 3 → 4 → 5 along the hysteresis loop. This phenomenon is consistent with the principle of the loop attenuation demagnetization method shown by the magnetization characteristic curve of the magnetic material. By this effect, the surface of the workpiece 3 made of a magnetic metal material is automatically demagnetized, and it can be expected that the residual magnetic abrasive grains are extremely reduced.

  That is, according to the present invention, the magnetic abrasive grain 2 is magnetically attached to the tip of the magnetic polishing tool 10 and then the workpiece 3 is polished by rotating relative to the workpiece 3 while rotating or rotating. Different magnetic poles 11 a and 11 b repeatedly pass over the workpiece 3 magnetized by the permanent magnet 11. As a result, it is possible to perform polishing while demagnetizing the magnetized workpiece 3 by the loop damping demagnetization principle. And since the magnetization of the workpiece 3 made of a magnetic metal material is weakened, the magnetic abrasive grains 2 remaining in the state of being magnetically attached to the surface of the workpiece 3 can be reduced, and the magnetic abrasive grains 2 used for polishing are placed between the magnetic poles. It can be held and polished efficiently.

  Although the permanent magnet 11 used for this invention is not specifically limited, A rare earth magnet, a ferrite magnet, an alnico magnet, MA magnet etc. can be mentioned. As the rare earth magnet, specifically, a neodymium magnet (Nd—Fe—B) or a samarium cobalt magnet (Sm—Co) is preferably used.

  Two or more permanent magnets 11 are used and are fixed to the yoke 12 in a state of being separated from each other. As shown in FIG. 2, the number of permanent magnets 11 may be two constituting an N pole and an S pole, or may be three, four, or five above. In short, it is sufficient that two or more permanent magnets 11 are fixed to the yoke 12 in a state of being separated from each other. When the number of permanent magnets is odd, one of the N and S poles is reduced by one, and when the number is even, the number of N and S poles is the same. It is preferable that a plurality of permanent magnets 11 be arranged at the same distance from the rotation axis or the center point of the rotation axis. As described above, the workpiece 3 magnetized by the loop damping demagnetization principle is polished while being demagnetized. Processing can be performed. Further, a plurality of permanent magnet groups having a short distance from the center point of the rotating shaft or the rotating shaft and a plurality of permanent magnet groups having a long distance from the center point of the rotating shaft or the rotating shaft are arranged. Also good. Also in this case, polishing can be performed while demagnetizing the workpiece 3 magnetized by the loop damping demagnetization principle. In addition, you may provide the permanent magnet group from which distance differs further.

  The size of the permanent magnet 11 is preferably a size according to the location to be arranged. For example, when the number of the permanent magnets 11 is set to an even number, the size is usually the same. preferable. In addition, since the magnitude | size of the permanent magnet 11 does not fluctuate | variate remarkably with the magnitude | size of a magnet, even if it is a small magnet, it has comparatively big magnetization and can magnetically adsorb magnetic abrasive grains etc. strongly. There is an effect.

  The yoke 12 is not particularly limited, and a yoke generally used as a yoke can be used. For example, the general structural rolled steel (SS400) shown in the Example mentioned later is used.

  Various types of magnetic abrasive grains 2 for forming the particle brush 2 'can be used. The magnetic abrasive grains 2 are preferably those having a degree of magnetism that is magnetically attracted to the magnet. For example, magnetic abrasive grains (Toyo Abrasives Industries Co., Ltd .; KMX-80) that are currently marketed only in Japan, and other non-commercially available products. Magnetic abrasive grains can be used, and magnetic grains having an abrasive function may be used. As such magnetic particles, iron materials such as electrolytic iron, nickel alloy materials such as nickel, Ni-P alloy, or Ni-B alloy can be used. In addition, as magnetic particles having an abrasive function, composite magnetic particles formed by forming a magnetic metal film (for example, nickel or nickel alloy plating film) on the surface of non-magnetic abrasive grains, or in an inert gas under high temperature and pressure It is also possible to use aluminum oxide sintered with iron and the product of the thermite reaction between aluminum and iron oxide in an inert gas atmosphere. In addition, although magnetic abrasive grains having a polishing action are preferably used, it is industrially preferable to add magnetic particles as an extending material. The blending ratio of the magnetic abrasive grains and the magnetic particles is set in consideration of their polishing ability and the workability of the workpiece.

Such magnetic abrasive grains may be used as they are, or may be used together with a slurry containing general abrasive particles as necessary. General abrasive particles include A, WA, GC, SA, MA, C, MD, CBN, etc. in accordance with JIS indication, Al ₂ O ₃ , SiC, ZrO ₂ , B ₄ C, diamond, cubic nitriding There may be mentioned those bonded with abrasive grains such as boron, MgO, CeO ₂ or fumed silica.

  Hereinafter, the present invention will be described more specifically with reference to examples. The scope of the present invention is not limited to the following examples.

Example 1
Magnetic polishing was performed using the magnetic polishing apparatus shown in FIG. 3 and FIG. A magnetic polishing tool 10 in which two permanent magnets 11a and 11b are spaced apart and fixed to a yoke 12 is prepared, and a magnetic brush 2 is magnetically attached to the tip of the tool 10 to form a particle brush 2 '. The jig 13 was fixed to the main spindle of the NC milling machine. On the other hand, an XY stage was mounted on an NC vertical milling machine table, and a SPCC magnetic steel plate as the workpiece 3 was mounted on the XY stage. After the tool 10 was lowered until the particle brush 2 'contacted the workpiece 3, the surface of the workpiece was polished by rotating the spindle of the NC milling machine. Furthermore, the entire surface of the workpiece was polished while feeding the workpiece on the XY stage. Table 1 shows the processing conditions at this time. Here, a polishing slurry is prepared using electrolytic iron powder as magnetic abrasive grains, diamond abrasive grains as an abrasive and a water-soluble polishing liquid as a polishing liquid, and this polishing slurry is magnetically applied to the tip of a tool. A particle brush 2 'was formed by wearing.

(Evaluation)
With respect to the processed surface of the workpiece after being polished under the above processing conditions, the processing amount and the surface roughness were evaluated. The processing amount was evaluated by measuring the weight of the workpiece before and after processing, and the surface roughness was evaluated by the maximum height Rz and the arithmetic average roughness Ra according to JIS B 0601 (2001). The pre-processed surface of the workpiece was set to a surface roughness of 7.1 μm Rz by manual processing using abrasive paper # 120. In the experiment, one experiment was stopped by four reciprocations, and ultrasonic processing was sufficiently performed to measure the processing amount and the surface roughness. Moreover, the processed surface after processing was observed with an electron microscope (100 times), and the surface form was observed. Further, the demagnetization effect was visually evaluated by comparing the results when the workpiece was given a feed motion and the magnetic polishing tool was rotated and not rotated.

(result)
FIG. 6 is a graph showing a profile of the surface roughness of the processed surface, and FIG. 7 is a graph showing a temporal change in the surface roughness of the processed surface and the processing amount. As shown in FIGS. 6 and 7, the processed surface after the four reciprocating processes is almost smoothed, and the surface roughness before processing is reduced from 7.1 μmRz (0.76 μmRa) to 0.90 μmRz (0.16 μmRa). The smoothness was improved. It can be seen that the surface roughness of the machined surface after the four reciprocations are gradually reduced, and the smoothness settles to a steady state after the eight reciprocations. On the other hand, it was confirmed that the processing amount increased linearly.

  FIG. 8 is an electron micrograph of the obtained workpiece surface. FIG. 8A shows the machined surface before machining, FIG. 8B shows the machined surface after 4 reciprocations, and FIG. 8C shows 8 reciprocations. The processed surface after performing is shown. As shown in the figure, it was confirmed that the rough surface before processing was almost uniform after processing. Under the present experimental conditions, the machining surface is not mirror-finished, but since a fine textured surface was observed, it is considered that the machining action of the particle brush 2 ′ is accompanied by the rolling phenomenon of the magnetic abrasive grains 2.

  FIG. 9 is a photograph comparing the residual phenomenon of magnetic abrasive grains, and FIG. 9A is a photograph of the workpiece surface after feeding the workpiece with the magnetic polishing tool rotated. FIG. 9B is a photograph of the workpiece surface after feeding the workpiece with the magnetic polishing tool not rotated. Comparing the two, the rotated FIG. 9A had fewer magnetic abrasive grains remaining on the workpiece surface, but the non-rotated FIG. 9B had the magnetic abrasive remaining on the workpiece surface. It can be seen that there are many grains. Also from this, it is clear that the work is demagnetized by rotating or rotating the magnetic polishing tool according to the present invention.

It is a schematic diagram which shows an example of the magnetic polishing apparatus of this invention. It is a drawing substitute photograph which shows an example of the tool for magnetic polishing used for the magnetic polishing apparatus of this invention. It is a drawing substitute photograph which shows the specific form in which the magnetic polishing apparatus of this invention has grind | polished a workpiece. 4 is a drawing-substituting photograph showing a specific form of the overall configuration of the magnetic polishing apparatus shown in FIG. 3. It is a principle diagram of the loop attenuation demagnetization method. In Example 1, it is a graph which shows the profile of the surface roughness of a process surface. In Example 1, it is a graph which shows the time change of the surface roughness of a process surface, and a process amount. In Example 1, it is an electron micrograph of the obtained workpiece surface. It is the photograph which compared the residual phenomenon of the magnetic abrasive grain. It is a schematic diagram which shows the example of the planar magnetic polishing apparatus provided with the conventional tool for magnetic polishing processes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic polishing apparatus 2 Magnetic abrasive grain 2 'Particle brush 3 Workpiece 4 Closed magnetic circuit 10 Magnetic polishing tool 11 Permanent magnet 11a N pole 11b S pole 12 Yoke 13 Fixing jig 14 Moving table

Claims (3)

  A magnetic polishing tool having a tip structure in which each of two or more permanent magnets that magnetically attract magnetic abrasive grains is fixed to be separated from the yoke is provided, and the magnetic abrasive grains are magnetically attracted to the tip of the magnetic polishing tool. A magnetic polishing apparatus for polishing a workpiece by moving the workpiece relative to the workpiece while rotating or rotating the workpiece.   2. The magnetism according to claim 1, wherein each of the two or more permanent magnets is an N pole or an S pole, and a closed magnetic circuit is configured between the N pole, the yoke, the S pole, and the magnetic abrasive grains. Polishing equipment. Each of the two or more permanent magnets that magnetically adsorb magnetic abrasive grains has a tip structure that is fixed to be separated from the yoke. After magnetically attracting magnetic abrasive grains to the tip, the workpiece is rotated or rotated on the workpiece. A magnetic polishing tool that polishes the workpiece by relative movement.

Images