JPH05162037A - Electromagnetic chuck - Google Patents

Abstract

PURPOSE:To prevent an exciting coil from the reduction of insulation resistance caused by liquid entering a gap between a housing and face plate by giving water proof and pliability softer than a first resin to a second resin. CONSTITUTION:Exciting current is supplied to a exciting coil 20 in the adsorption of a magnetic body, so that an operating surface is set to the excited condition by magnetic fluxes generated from the exciting coil 20 and the magnetic body is attracted to the operating surface. When the magnetic body is released, the supply of the exciting current to the exciting coil 20 is stopped. As a result, the operating surface is set to the non-exciting condition and the magnetic body is released from the operating surface. Then, the exciting coil 20 is maintained at a predetermined position of a recess 22 by a first resin 24. Since a second resin 26 is harder than the first resin 24, the second resin 26 has few possibility of forming cracks even if the second resin 26 is repetitively compressed and expanded by the repetitive use of an electromagnetic chuck, so that the exciting coil 20 is protected from liquid entering a gap between a housing 16 and face plate 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic chuck that magnetically grips a magnetic body using an electromagnet.

[0002]

2. Description of the Related Art In an electromagnetic chuck in which an electromagnet is arranged in a housing having one end open and a face plate is arranged in the open end of the housing, an exciting coil of the electromagnet is formed by the housing and an iron core and is continuous around the iron core. The thermosetting epoxy resin filled in the recess so as to surround the exciting coil,
The excitation coil is positioned with respect to the housing and the iron core, and is protected from liquid that has entered the gap between the housing and the face plate.

However, since the epoxy resin surrounding the exciting coil receives heat generated from the exciting coil during use of the electromagnetic chuck, repeated use of the electromagnetic chuck causes the epoxy resin to repeatedly expand and contract, As a result, cracks are formed in the epoxy resin.

When cracks are formed in the epoxy resin surrounding the exciting coil in this way, liquids such as cooling water and machining fluid that have entered the gap between the housing and the face plate are excited from the cracks in the epoxy resin. , The insulation resistance of the exciting coil decreases.

If a resin softer than an epoxy resin is used to solve this problem, the position of the exciting coil with respect to the housing and the iron core becomes unstable.

[0006]

The object of the present invention is to stabilize the position of the exciting coil with respect to the housing and the iron core, and to reduce the insulation resistance of the exciting coil due to the liquid entering the gap between the housing and the face plate. It is to be prevented.

[0007]

A magnetic chuck according to the present invention defines a housing having one end open, and an iron core arranged in the housing, the space extending continuously around the iron core in cooperation with the housing. An iron core, an exciting coil arranged in the space around the iron core, a work surface for attracting a magnetic substance, a face plate arranged at the open end of the housing, and an outer surface of the exciting coil. A first resin disposed in the space so as to cover the space, and a second resin disposed at the open end of the space and liquid-tightly closing the space at the open end of the space, The second resin has water resistance and is softer than the first resin.

When attracting the magnetic substance, an exciting current is supplied to the exciting coil. As a result, the work surface is excited by the magnetic flux generated by the exciting coil, and the magnetic substance is attracted to the work surface. When the magnetic body is released, the supply of the exciting current to the exciting coil is stopped. As a result, the work surface is placed in a non-excited state, and the magnetic body is released from the work surface.

The exciting coil is maintained at a predetermined position in the recess by the first resin. Since the second resin is softer than the first resin, the second chuck can be used repeatedly by repeatedly using the electromagnetic chuck.
Even if the resin is repeatedly expanded and contracted, the second resin is less likely to be cracked, and as a result, the exciting coil is protected from the liquid that has entered the gap between the housing and the face plate.

According to the present invention, the outer surface of the exciting coil is covered with the first resin, and the open end portion of the space in which the exciting coil is arranged has the water resistance and is softer than the first resin. Since it is liquid-tightly closed by resin, the position of the exciting coil with respect to the housing and the iron core is stabilized, and the insulation resistance of the exciting coil due to the liquid entering into the gap between the housing and the face plate is prevented from decreasing. To be done.

The face plate has a plurality of first and second elongated strips, which are alternately arranged in one direction with a non-magnetic spacer interposed therebetween and cooperate with the spacer to define recesses which open toward the housing. A pole piece may be included. Furthermore, in this case, it is preferable that the recess be liquid-tightly closed by a third resin having water resistance and softer than the first resin. This prevents liquid such as cooling water from entering the space between the housing and the face plate through the space between the first magnetic pole piece and the spacer or the space between the second magnetic pole piece and the spacer.

Further, it is preferable to cover the outer surface of the first resin with a fourth resin having water resistance and softer than the first resin. Thereby, the exciting coil is more reliably protected from the liquid.

The first resin may be a thermosetting epoxy resin, and the second, third and fourth resins may be polyurethane type synthetic resins.

[0014]

Embodiments of the magnetic chuck of the present invention shown in the drawings will be described below. Although an example of a magnetic chuck using only an electromagnet as a magnetic flux generation source will be described below, the present invention can be applied to a magnetic chuck using an electromagnet and a permanent magnet.

The magnetic chuck 10 shown in FIGS. 1 to 4 includes a flat rectangular main body 12 and a flat rectangular face plate 14 disposed on the main body.

As shown in FIGS. 2 to 4, the main body 12 includes a bottom portion 16a and a peripheral wall portion 16b rising from the peripheral edge of the bottom portion 16a.
Housing 1 in the shape of an elongated box that opens upwards by
6 and an iron core 18 extending in the longitudinal direction of the housing 16 in the widthwise central portion of the housing 16 inside the housing 18.
And an exciting coil 20 wound around the iron core 18.

The housing 16 and the iron core 18 are made of a magnetic material and define a space 22 continuously extending around the iron core 18. The exciting coil 20 is arranged in the space 22. The exciting coil 20 is covered with the first resin 24 filled in the space 22. Space 22
The open end of the second resin 26 disposed at the open end.
It is liquid-tightly closed by.

The face plate 14 is arranged on the housing 16 so as to close the opening of the housing 16. Face plate 1
4 is a housing 16 with a non-magnetic spacer 28 in between.
A plurality of elongated first and second pole pieces 30 and 32 arranged alternately in the longitudinal direction.

The first pole piece 30 is magnetically connected to the peripheral wall portion 16b of the housing 16, but is magnetically insulated from the iron core 18. The second magnetic pole piece 32 is the iron core 1.
8, but is magnetically insulated from the peripheral wall portion 16b of the housing 16.

The spacer 28 and the first and second magnetic pole pieces 30 and 32 cooperate with each other to define a work surface for adsorbing a workpiece made of a magnetic material on the upper surface of the face plate 14, and on the housing 16 side. The recesses 34 that jointly define the open recesses 34 are liquid-tightly closed by a third resin 36 arranged in the recesses.

In the illustrated example, the face plate 14 is provided with a plurality of first grooves having a predetermined depth dimension and a constant pitch from the upper surface side of a plate body having a predetermined thickness dimension. Between the first magnetic pole piece 3 and the longitudinal end portions of the face plate.
And a second groove that extends in the longitudinal direction of the iron core and communicates with the first groove is formed at a portion of the lower surface of the plate body facing the upper surface of the iron core 18, The second magnetic pole piece 32 is housed in the groove of the
A portion of the second pole piece 32 is projected from the second groove to magnetically contact the first and second pole pieces 3;
The spacers 28 are arranged between 0 and 32, and the spacers 28 and the first and second magnetic pole pieces 30 and 32 are fixed to each other by a non-magnetic material such as solder.

However, the face plate 14 may be formed by alternately stacking the first magnetic pole pieces 30 and the second magnetic pole pieces 32 with the non-magnetic spacer 28 interposed therebetween.

A notch is provided in each of the magnetic pole pieces (first magnetic pole piece 30 in the illustrated example) located at both ends of the face plate 14, and an auxiliary magnetic pole piece 38 is fitted in each of the notches. Each auxiliary magnetic pole piece 38 is magnetically insulated from each adjacent member.

As the first resin 24, a relatively hard thermosetting resin such as an epoxy resin is used. On the other hand, as the second and third resins 26 and 36, resins such as polyurethane resins that are softer and more water resistant than epoxy resins are used.

Therefore, since the first resin is a relatively hard thermosetting resin, the exciting coil 20 has the first resin 2
4 keeps it in a stable position in the recess.

On the other hand, the second and third resins 26,
Since 36 is a relatively soft resin, even if the second and third resins 26, 36 expand and contract repeatedly due to repeated use of the electromagnetic chuck 10, the second and third resins 26, 3
There is little possibility that cracks will be formed in No. 6.

As a result, the exciting coil 20 has the face plate 14
The liquid is protected from the liquid that has entered the gap between the housing 16 and the housing 16, and the insulation resistance of the exciting coil 20 is prevented from decreasing. In addition, liquid such as cooling water may enter between the face plate 14 and the housing 16 through the gap between the spacer 28 and the first magnetic pole piece 30 or the gap between the spacer 28 and the second magnetic pole piece 32. Is prevented.

When the magnetic chuck 10 is used, a current is supplied to the exciting coil 20 so that the side of the iron core 18 becomes S, for example. As a result, the first magnetic pole piece 30 is biased to N via the iron core 18 and the peripheral wall portion 16 a of the housing 16, and the second magnetic pole piece 32 is biased to S via the iron core 18. As a result, the work surface of the face plate 14 is placed in an excited state,
The magnetic substance is adsorbed on the work surface. When the supply of current to the exciting coil 20 is stopped, the work surface is placed in a non-excited state,
The adsorbed magnetic substance is released.

As shown in FIGS. 5 and 6, a fourth resin 40, which is softer and more water resistant than an epoxy resin, such as a polyurethane resin, is attached to the outer surface of the first resin 24. It is preferable to arrange it in the space 22 so as to cover the. By doing so, the exciting coil 20 is more reliably protected from the liquid.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a magnetic chuck of the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG.

FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG.

FIG. 5 is a sectional view similar to FIG. 3 showing another embodiment.

FIG. 6 is a sectional view similar to FIG. 4, showing another embodiment.

[Explanation of symbols]

 10 magnetic chuck 12 main body 14 face plate 16 housing 18 iron core 20 exciting coil 22 space 24 first resin 26 second resin 28 non-magnetic spacer 30 first magnetic pole piece 32 second magnetic pole piece 34 recess 36 third Resin 38 Auxiliary pole piece 40 Fourth resin

Claims (4)

[Claims] 1. A housing having an open end, an iron core disposed in the housing, the iron core defining a space that continuously extends around the iron core in cooperation with the housing, and an iron core disposed around the iron core. And a face plate disposed at the open end of the housing and having an exciting coil disposed in the space and a work surface for attracting a magnetic substance, and disposed in the space so as to cover the outer surface of the exciting coil. The second resin includes a first resin and a second resin that is disposed at an open end of the space and liquid-tightly closes the space at the open end of the space. An electromagnetic chuck that has and is softer than the first resin. 2. A plurality of first and first elongated strips, which are arranged alternately in one direction with a non-magnetic spacer in between and define together with the spacer a recess opening to the side of the housing. Two magnetic pole pieces, one of the first and second magnetic pole pieces being magnetically connected to one of the housing and the iron core, and the other of the first and second magnetic pole pieces being the housing and the iron core. A plurality of first and second magnetic pole pieces magnetically connected to the other of the first and second magnetic pole pieces, and a third resin which is disposed in the recess and liquid-tightly closes the recess. The electromagnetic chuck according to claim 1, wherein the resin has water resistance and is softer than the first resin. 3. A fourth resin disposed in the space so as to cover the outer surface of the first resin, the fourth resin having water resistance, and the first resin. The electromagnetic chuck according to claim 1 or 2, which is softer than the resin. 4. The electromagnetic chuck according to claim 3, wherein the first resin is a thermosetting epoxy resin, and the second, third, and fourth resins are polyurethane-based synthetic resins.