JPH0544021Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to an electromagnetic chuck having a plurality of annular magnetic pole face portions concentrically on a working surface, and particularly to an electromagnetic chuck suitable as a round electromagnetic chuck.

(Prior art) As one of the ring pole type electromagnetic chucks,
It has an electromagnetic chuck. This electromagnetic chuck includes a face plate having a plurality of annular first and second magnetic pole pieces concentrically on the working surface, a housing including a bottom plate and a frame rising from the periphery of the bottom plate, and a housing including an annular first and second magnetic pole piece. It includes an iron core and a plurality of annular electromagnets each having an excitation coil disposed outside the iron core.

In an electromagnetic chuck, the first and second
The pole pieces are alternately arranged in the radial direction of the faceplate with non-magnetic material in between. The face plate is disposed on the opposite side of the housing from the bottom plate so as to close the opening of the upwardly opening annular recess defined by the bottom plate and the frame of the housing. The electromagnet is arranged concentrically within the recess of the housing so that it is magnetized in a direction perpendicular to the working surface. The first pole piece is magnetically connected to one pole face of the electromagnet through the housing, and the second pole piece is magnetically connected directly to the other pole face of the electromagnet.

However, in conventional electromagnetic chucks, the excitation coil is placed between both iron cores of adjacent electromagnets, so even if the electromagnetic chuck magnetizes adjacent electromagnets in different directions, the first and second
If you try to make the arrangement pitch of the magnetic pole pieces smaller than the arrangement pitch of the electromagnets (for example, to 1/2), the magnetic pole pieces placed between the two iron cores of adjacent electromagnets, that is, in the area corresponding to the arrangement area of the excitation coil, will be It becomes an auxiliary pole piece that is not magnetically connected to the electromagnet.

In an electromagnetic chuck with many auxiliary magnetic pole pieces, the magnetic flux is only induced into the auxiliary magnetic pole pieces from the first and second magnetic pole pieces that are magnetically connected to the magnetic pole face of the electromagnet, so that the chuck as a whole cannot be attracted. It has the disadvantage of decreasing power. In addition, since the magnetic flux generated from the first and second magnetic pole pieces is stronger than that from the auxiliary magnetic pole piece, when trying to attract a small magnetic body, the magnetic body may fall into the first or second magnetic pole piece. It has the disadvantage of being inverted in the . Furthermore, since the auxiliary pole piece is only supported by the side portions of the auxiliary pole piece by the first and second pole pieces adjacent to it,
When a force is applied to an auxiliary pole piece in a direction perpendicular to the working surface, the auxiliary pole piece is moved in the direction of the force with respect to the first and second pole pieces on either side of it, with the result that the auxiliary pole piece is moved in the direction of the force. There is a drawback that smoothness is impaired.

Another type of ring pole type chuck is a permanent magnet type chuck. This permanent magnet type chuck has a magnet device consisting of a polarity changing permanent magnet and an excitation coil that reverses the magnetization direction of the permanent magnet instead of each electromagnet, and an annular magnet arranged concentrically between the electromagnet group and the face plate. A plurality of fixed polarity permanent magnets are used. In this permanent magnetic chuck, an annular yoke is arranged concentrically between adjacent polarity fixed permanent magnets, each polarity fixed permanent magnet is arranged in a position aligned with an excitation coil of a magnet device,
Each yoke is positioned in alignment with a polarity changing permanent magnet.

However, in this permanent magnet type chuck, fixed polarity permanent magnets and yokes are arranged alternately in the radial direction of the working surface, and polarity changing magnets and excitation coils are arranged alternately in the radial direction of the working surface. Therefore, if an attempt is made to make the arrangement pitch of the first and second magnetic pole pieces smaller than the arrangement pitch of the fixed polarity permanent magnet and the magnet device, the magnetic pole pieces arranged at the position corresponding to the arrangement position of the excitation coil and the fixed polarity permanent magnet will be becomes an auxiliary pole piece that is not magnetically connected to any permanent magnet. Therefore, such permanent magnetic chucks suffer from the same drawbacks as the electromagnetic chucks described above.

As yet another type of ring-pole electromagnetic chuck, a plurality of electromagnets each having an iron core having a fan-shaped or trapezoidal planar shape are placed in an annular recess so that the direction of magnetization thereof is perpendicular to the working surface. Some electromagnets are arranged at a predetermined pitch in the circumferential direction along the surface, and each electromagnet is magnetized in the same direction to keep the work surface in an excited state. However, with this electromagnetic chuck,
The upper surface of the electromagnet's iron core and the upper surface of the housing frame act as a magnetic pole surface that is magnetically connected to the face plate, so if you try to reduce the arrangement pitch of the first and second magnetic pole pieces, the magnetic pole surface will An auxiliary pole piece, which is not magnetically connected to either pole face, must be placed between the first and second pole pieces which are connected to each other. Therefore, such an electromagnetic chuck suffers from the same drawbacks as the electromagnetic chuck described above.

(Purpose of the invention) The present invention provides an electromagnetic chuck that can reduce the number of auxiliary pole pieces that are not magnetically connected to either pole face even if the arrangement pitch of the first and second magnetic pole pieces is reduced. The purpose is to provide.

(Structure of the invention) The electromagnetic chuck of the invention includes a housing including a bottom plate portion and a frame portion rising from the bottom plate portion, and a housing having an upwardly opening recess defined by the bottom plate portion and the frame portion; A plurality of annular first magnetic pole face parts and an annular face plate arranged on the opposite side of the bottom plate part of the housing and arranged alternately to define a working surface that attracts magnetic material. a plurality of electromagnets comprising a face plate concentrically having a plurality of second magnetic pole face portions, an iron core and an excitation coil disposed around the iron core, the magnetic flux passing through the iron core in a direction perpendicular to the working surface; a plurality of electromagnets for selectively switching the working surface between an energized state and a de-energized state, which are sequentially arranged at intervals along a virtual circle concentric with the magnetic pole face part in the recess; a plurality of magnetic members arranged in the recess so as to extend in the radial direction of the virtual circle between adjacent electromagnets, and magnetically connected to one magnetic pole surface of the electromagnet via the housing; and a plurality of magnetic members magnetically connected to the other magnetic pole surface of the electromagnet via the face plate.

(Effect of the invention) In the magnetic chuck of the invention, magnetic members extending in the radial direction of the virtual circle are arranged between the adjacent electromagnets, and each magnetic member is attached to one magnetic pole surface of the electromagnet through the housing. It is magnetically connected to the other magnetic pole face of the electromagnet via the face plate.

Therefore, according to the present invention, even if the arrangement pitch of the first and second magnetic pole pieces is small, many of the magnetic pole pieces are magnetically connected to one magnetic pole surface of the electromagnet through the housing. and the other magnetic pole face of the electromagnet, so
Auxiliary pole pieces that are not magnetically connected to the electromagnet are significantly reduced.

(Example) Hereinafter, an example of the present invention shown in the drawings will be described.

The electromagnetic chuck 10 shown in FIGS. 1 to 4 has a housing 1 made of a magnetic material and having a circular planar shape.
Contains 2. The housing 12 includes a disc-shaped bottom plate portion 1
4, a cylindrical frame portion 16 rising from the peripheral edge of the bottom plate portion, and a protruding portion 18 projecting upward from the center of the bottom plate portion 14, and the bottom plate portion 14, the frame portion 1
6 and an annular recess 20 defined by the protrusion 18 . The recess 20 opens upward.

In the recess 20, a plurality of electromagnets 22 are sequentially arranged at intervals in the circumferential direction of the recess 20. Each electromagnet 22 has an iron core 24 made of magnetic material.
and an excitation coil 26 arranged around the iron core.
and an intermediate plate 28 made of a magnetic material placed on top of the iron core 24, and arranged so that the direction of magnetic flux passing through the iron core 24 is in the vertical direction. The iron core 24 has a height dimension that is approximately the same as a depth dimension of the recess 20. Therefore, the middle plate 28 protrudes from the recess 20.

In the illustrated example, the iron core 24 is manufactured separately from the housing 12 and then fixed to the bottom plate portion 14 by welding or the like, but it may be provided integrally with the housing 12 by processing the housing 12. Further, the iron core 24 may be made of a permanent magnetic material. Furthermore, a portion corresponding to the intermediate plate 28 may be integrally formed in the iron core 24, or the intermediate plate 28 or a portion corresponding thereto may not be provided.

Plate-shaped magnetic members 30 are arranged between adjacent electromagnets 22 in the recesses 20, respectively. Each magnetic member 30 rises upward from the bottom of the recess 20 and extends in the radial direction of the recess 20 so as to mutually partition areas where adjacent electromagnets 22 are arranged. Each magnetic member 30 has a height dimension that is approximately the same as a depth dimension of the recess 20 . In the illustrated example, each magnetic member 30 is manufactured separately from the housing 12 and then fixed to the bottom plate portion 14 by welding or the like, but it may also be provided integrally with the housing 12 by processing the housing 12. good.

Electromagnetic chuck 10 also includes a face plate 34 having a working surface 32 for attracting magnetic material. Face plate 34
is disposed on the opposite side of the housing 12 from the bottom plate portion 14 with the working surface 32 facing up so as to close the opening of the recess 20, and is attached to the housing 12 by a plurality of bolts. Face plate 34
includes a plurality of annular first magnetic pole pieces 36 and a plurality of annular second magnetic pole pieces 38 . The first and second magnetic pole pieces 36, 38 are arranged alternately and concentrically with a non-magnetic member 40 therebetween, and
A plurality of annular first and second magnetic pole face portions are defined on the work surface 32.

The first pole pieces 36 are each magnetically connected to the pole face of the iron core 24 on the face plate 34 side via the middle plate 28 of the electromagnet 22 and are magnetically isolated from the magnetic member 30 . On the other hand, the second magnetic pole pieces 38 are each magnetically connected to the magnetic member 30 and magnetically isolated from the intermediate plate 28 and thus from the magnetic pole face on the face plate 34 side of the iron core 24 . The outer periphery 42 and the inner periphery 44 of the face plate 34 are each magnetically connected to the housing 12 while being magnetically isolated from the middle plate 28;
The outer periphery 42 and the inner periphery 44 thus constitute a pole piece that acts similarly to the second pole piece 38.

The first magnetic pole piece 36 and the face plate 3 arranged on the outermost periphery
4, that is, between the magnetic pole piece 42, and
A first magnetic pole piece 36 and a face plate 34 arranged at the innermost circumference
An annular auxiliary magnetic pole piece 46 is arranged concentrically with each magnetic pole piece on the inner peripheral portion thereof, that is, between the magnetic pole pieces 44 . A non-magnetic member 40 is also arranged between both auxiliary pole pieces 46 and the adjacent pole pieces 36, 42, 44 of the auxiliary pole pieces. Note that if the magnetic pole pieces are arranged so that the first magnetic pole piece 36 is located at the position of the auxiliary magnetic pole piece 46, the auxiliary magnetic pole piece 46 can be omitted.

As shown in FIGS. 2 and 4, the recess 20 of the housing 12 is filled with electrically and magnetically insulating resin 48. As shown in FIGS. The excitation coil 26 is fixedly maintained within the recess 20 by the resin 48 . Each magnetic pole piece 3 is also provided in the space 50 of the face plate 34.
A non-magnetic material may be filled in order to fix the positional relationship of 6, 38, 42, 44, and 46.

When the electromagnetic chuck 10 is in use, the excitation coil 26 of each electromagnet 22 is supplied with an excitation current such that the iron core 24 is magnetized in the same direction. This results in
The first pole piece 36 is energized to one polarity, for example N, and the second pole piece 38 is energized to the other polarity, eg S.
Since the working surface 32 is energized, the working surface 32 is placed in an excited state, and the magnetic material can be attracted to the working surface.

When the iron core 24 is made of a normal magnetic material, the excitation current is applied while adhering the magnetic material to the work surface.
It is supplied to the excitation coil 26. However, iron core 24
is made of a permanent magnet material, the excitation coil operates for a short period of time, that is, until the iron core 24 is magnetized.
It is supplied to the excitation coil 26.

When releasing the magnetic material attracted to the work surface 32, a damping alternating current is supplied to the excitation coil 26. As a result, an attenuating alternating magnetic field acts on the magnetic body and the iron core 24, so that the magnetic body and the iron core 24 are demagnetized, and the magnetic body attracted to the work surface is removed from the work surface 32.

According to the electromagnetic chuck 10, the magnetic member 30 disposed between the electromagnets 22 extends in the radial direction of the recess 20, so that many of the pole pieces are magnetically connected to the electromagnets and thus magnetically connected to the electromagnets 22. There are significantly fewer unconnected auxiliary pole pieces. As a result, the attraction force of the electromagnetic chuck as a whole is increased, and a small magnetic body is not inverted at the first or second magnetic pole piece. Furthermore, since many magnetic pole pieces are in contact with either the middle plate 28 or the magnetic member 30, even if a force is applied to each magnetic pole piece to push it into the recess 20 of the housing 12, the magnetic pole piece midplate 28 or magnetic member 30 prevents one pole piece from being forced into recess 20 relative to another pole piece;
Therefore, the smoothness of the work surface 32 is maintained.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a quarter of the electromagnetic chuck of the present invention, with a part of the face plate removed to show the inside of the housing, and Fig. 2 is a plan view showing the inside of the housing, taken along line 2-2 in Fig. 1. The obtained sectional views, FIG. 3, are the sectional views taken along the line 3--3 in FIG. 1, and FIG. 4 is the sectional view taken along the line 4--4 in FIG. 10...Electromagnetic chuck, 12...Housing,
14... bottom plate part, 16... frame part, 20... recess,
22... Electromagnet, 24... Iron core, 26... Excitation coil, 30... Magnetic member, 32... Work surface, 34
...Face plate, 36...First magnetic pole piece, 38...Second
magnetic pole piece, 40... non-magnetic member.

Claims (1)

[Claims for Utility Model Registration] (1) A housing comprising a bottom plate portion and a frame portion rising from the bottom plate portion, and having a recess defined by the bottom plate portion and the frame portion and opening upward; A plurality of annular first magnetic pole face parts and an annular face plate arranged on the opposite side of the bottom plate part of the housing to close the opening and arranged alternately to define a working surface that attracts magnetic material. A plurality of electromagnets comprising a face plate concentrically having a plurality of second magnetic pole face parts, an iron core and an excitation coil arranged around the iron core, the magnetic flux passing through the iron core in a direction orthogonal to the working surface. a plurality of electromagnets for selectively switching the working surface between an energized state and a de-energized state, which are sequentially arranged at intervals along an imaginary circle concentric with the magnetic pole surface part in the recess; a plurality of magnetic members arranged in the recess so as to extend in the radial direction of the virtual circle between the matching electromagnets, and magnetically connected to one excitation surface of the electromagnet through the housing; and a plurality of magnetic members magnetically connected to the other magnetic pole surface of the electromagnet via the face plate. (2) The electromagnetic chuck according to claim 1, wherein the magnetic member is arranged in the recess so as to be in contact with the face plate and the bottom plate.