JPS60150930A - Magnetic chuck - Google Patents

Abstract

PURPOSE:To obtain a uniform magnetic chuck by burying a permanent magnet into the face plate which contacts with a workpiece and leading the magnetic flux of the permanent magnet and the induced magnetic flux by the electromagnetic coil of a chuck body to the electromagnetic-coil side. CONSTITUTION:When the attraction action by the magnetic flux phip due to a permanent magnet 4 and the attraction by the magnetic flux phie1 due to an electromagnetic coil 2 are performed, a workpiece can be strongly attracted onto the face plate 3 of a chuck body 1. When the exciting current of the electromagnetic coil 2 is reversed, a magnetic flux phie2 is generated in the direction for leading the magnetic flux phip due to the permanent magnet 4 towards the coil iron core side, and the magnetism of the permanent magnet 4 is increased, and the relation phip phie2 is established. The magnetic flux generated by the electromagnet 2 is desirably the magnetic flux in the degree in which the face plate 3 can be a little excited phie3 reversely, and the magnetism of the permanent magnet 4 can be also increased. Therefore, the generated magnetic flux of the electromagnetic coil can be utilized even in attraction, and a uniform magnetic chuck free from the part where the magnetism on attraction is weak can be obtained because of the permanent magnet.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a magnetic chuck, and includes: 41! The present invention relates to a magnetic chuck that attracts a workpiece using both the magnetic force of a permanent magnet and the magnetic force of an electromagnet.

[Technical background]

In addition to the electromagnetic type and the electromagnetic type, magnetic chucks include a combination of the electromagnetic type and the electromagnetic type called the electropermanent type. This incorporates a permanent magnet and an electromagnetic coil into the chuck body, and when it is attracted, the magnetic flux of the permanent magnet acts on the workpiece through the face plate magnetic pole, and when it is released, the polarity of half of the permanent magnet is changed by the electromagnetic coil. The magnets form a closed magnetic path inside the chuck, and magnetic flux is prevented from exiting to the face plate magnetic pole side.

In conventional electropermanent magnetic chucks, the fixed magnet is a ferrite magnet with a high coercive force, and the polarity conversion magnet is an alnico magnet with a smaller coercive force than a ferrite magnet (in other words, the polarity can be easily reversed by an electromagnetic coil) and a high magnetic flux density. is used. Since alnico magnets use cobalt, their use has recently been avoided due to cost and resource concerns. It is also possible to replace the alnico magnet with an electromagnet with a core made of soft iron, which has a performance advantage over that of the alnico magnet.

However, when viewed from the electromagnetic chuck side, this configuration has the following problems. Namely.

When using a magnetic chuck, especially for thin or small workpieces, it is necessary to divide the magnetic poles into smaller pieces, but in this case, more magnetic flux passes through the separator between the magnetic poles, weakening the attraction force in whole or in part. There is a problem.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and provides a magnetic chuck that can effectively attract a workpiece by effectively adding the magnetic flux generated by the electromagnetic coil to the magnetic flux of the permanent magnet.

[Summary of the invention]

To achieve this objective, in the present invention, a permanent magnet is embedded in the face plate that contacts the workpiece, and an electromagnetic coil is embedded in the chuck body. The present invention also provides a magnetic chuck that attracts and releases a workpiece by excitation to guide the magnetic flux of the permanent magnet to the chuck body.

The present invention will now be described by way of example with reference to the accompanying drawings.

1A and 1B show an embodiment of the present invention, in which a chuck body 1 is provided with an electromagnetic coil 2, and a face plate 3 is provided with a permanent magnet 4 and a non-magnetic member 5.

The face plate 3 has a magnetic pole connected to the magnetic pole of the chuck body 1, and a permanent magnet 4'j6 and a nonmagnetic member 5 arranged between the magnetic poles. Both the permanent magnet 4 and the non-magnetic member 5 are arranged so as to straddle the magnetic poles, the permanent magnet 4 being arranged on the chuck body 1 side, and the non-magnetic member 5 on the attracting surface side. Permanent magnet 4
is magnetized so that the magnetic flux φ reaches one magnetic pole from the permanent magnet 4, reaches the other magnetic pole via a workpiece (not shown), and returns to the permanent magnet 4. In other words, the magnetic flux φ generated by the permanent magnet 4.

is configured to revolve around the non-magnetic member 5. The electromagnetic coil 2 can generate magnetic flux in two directions, positive and negative, depending on the direction of the energizing current.

In Fig. 1(a), the magnetic flux φ generated by the permanent magnet 4, and the phase 7JU
In Fig. 1(b), the direction of the magnetic flux generated by the permanent magnet 4 is changed so that the magnetic flux φ, flows toward the 4-magnetic coil. ,
'α magnet φe2 is approximately equal to φ.

Moreover, the magnetic flux φ8□ coincides with the direction in which the permanent magnet 4 is magnetized.

In other words, in the case of FIG.
Attraction is performed by magnetic flux φ8□. Therefore, the workpiece can be strongly attracted.0 On the other hand, in the case of the same figure (b), the energizing current of the electromagnetic coil 2 is reversed, and the magnetic flux φ8 to occur.

At this time, the direction of the permanent magnet 4 is such that the permanent magnet 4 is magnetized, and φ and φ8□ are approximately equal. The magnetic flux generated by the electromagnet 2 is preferably set to a level that can slightly reverse excite (φes) the face plate.

This also has an effect of increasing the magnetization of the permanent magnet 4.

FIGS. 2(a) and 2(b) show an embodiment of the pond of the present invention, and the difference from the embodiment of FIG. 1 is that the magnetic pole pitch in the face plate is set to IA.

That is, another magnetic pole 32 is inserted between the magnetic poles 31 of the face plate in FIG. 1 to narrow the magnetic pole spacing, and the number of permanent magnets and magnetic poles to be inserted between the magnetic poles increases accordingly.

By increasing the number of magnetic poles and making the magnetic pole pitch finer in this way, it becomes easier to attract a workpiece such as a thin iron plate.

Regarding the material that was not particularly mentioned in the description of each of the above embodiments, it is preferable that the permanent magnet 4 has a high magnetic force such as a ferrite magnet or a rare earth magnet. Also, the non-magnetic member 5
As the material, commonly used materials such as brass, stainless steel, and resin may be used.

〔Effect of the invention〕

As described above, the present invention includes a method in which a permanent magnet is embedded in a face plate that contacts a workpiece, and a magnetic flux added to the magnetic flux of the permanent magnet and the magnetic flux of the permanent magnet are guided to the electromagnetic coil side by an electromagnetic coil provided in the chuck body. Unlike conventional electropermanent chucks, the magnetic flux generated by the electromagnetic coil can be used during attraction, and due to the effect of the permanent magnet, the tE (
Unlike the M chuck, it is possible to provide a uniform magnetic chuck without any parts where the magnetic force is weak during adsorption.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are longitudinal sectional views and enlarged longitudinal sectional views for explaining the adsorption state 2 and release state of an embodiment of the present invention, and FIGS. 2(a) and (b) are the same. FIG. 7 is a vertical cross-sectional view for explaining the adsorption and release of another embodiment. 1... Chuck body, 2... Electromagnetic coil, 3...
Face plate, 4... Permanent magnet, 5... Non-magnetic member. Applicant's agent Kiyoshi Inomata h1 (2) (b) Procedural amendment February 4, 1980 Commissioner of the Patent Office Kazuo Wakasugi 1, Indication of case 1981 Patent Application No. 4780 3, Person making the amendment Relationship to the case Patent applicant 7 Jijiko Co., Ltd. 6, in the “Detailed description of the invention” column of the specification to be amended (1) Between the negative line 6 and 7 of the specification 4, “[Example]” ” is inserted. (2) On page 6, line 10, ``increase'' next to ``the number of magnetic poles'' should be corrected to ``increase.'' (3) On page 6, line 15, ``magnetic force'' in brackets is corrected to ``holding force.''

Claims (1)

[Claims] 1. A permanent magnet is embedded in the face plate that contacts the workpiece, and an electromagnetic coil is provided in the chuck body, and the electromagnetic coil is used to excite and generate a magnetic flux that is added to the magnetic flux of the permanent magnet. A magnetic chuck that attracts and releases a workpiece by energizing the magnetic flux of a permanent magnet to guide it to the chuck body. 2. In the magnetic chuck described in claim 1, the electromagnetic coil performs excitation to guide the magnetic flux of the permanent magnet facing the face plate to the chuck body, and the direction of excitation is such that the magnetic flux of the permanent magnet is directed toward the face plate. Magnetic chuck which is the direction of magnetization.