JPH0480780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a magnetic chuck that holds a magnetic material by magnetic force.

(Prior art) As one of the means for fixing a workpiece made of a magnetic material, Japanese Utility Model Publication No. 46-28780 and Utility Model Publication No. 48-48
Publication No. 39734, Publication of Utility Model Publication No. 51-21430, Publication of Utility Model Publication No. 1983
There is a magnetic chuck as described in Publication No.-150441.

This known magnetic chuck includes a magnetic source, such as an electromagnetic device or a permanent magnet assembly, and a housing containing the magnetic source. The housing is provided with a face plate portion made of a magnetic material for defining an adsorption surface serving as a processing reference surface of the chuck. In order to magnetically divide the face plate portion into different magnetic pole portions that are respectively magnetized to S and N poles by the magnetic source, a number of concave grooves open to the outer surface of the face plate portion are formed. There is. This concave groove is filled or buried with a non-magnetic material such as a synthetic resin material or brass, and by placing the non-magnetic member in the concave groove, the suction surface, which serves as a processing reference surface, is continuous. It is said to be a flat surface.

In the conventional magnetic chuck,
Publication No. 39734, Publication of Utility Model Publication No. 51-21430, Publication of Utility Model Publication No. 1983
When the adjacent magnetic pole parts are connected at the bottom of the concave groove, as in the magnetic chuck described in Publication No. 150441, etc., the part that defines the bottom surface of the concave groove, that is, the adjacent magnetic pole parts The connecting portion has a thickness dimension that magnetically saturates when magnetic flux from the magnetic source acts on the portion. When the part is magnetically saturated, the magnetic flux that cannot pass through the part will inevitably appear on the attracting surface, which will put the attracting surface in an excited state,
Further, a workpiece made of a magnetic material is attracted to the attraction surface.

However, in the conventional magnetic chuck,
As described above, on the outer surface of the face plate portion,
Since the non-magnetic member, which is made of a different material from the face plate portion, is filled or buried so as to be exposed, there is a difference between the non-magnetic member partially exposed on the attraction surface and the magnetic material constituting the face plate portion. Due to the difference in hardness, a local difference in hardness occurs on the suction surface. Uniform abrasion of the suction surface does not impair the flatness of the suction surface, but the above-mentioned local hardness difference on the suction surface causes partial, ie, uneven wear on the face plate. The flatness of the face plate is lost relatively quickly. Furthermore, due to the difference in coefficient of thermal expansion between the non-magnetic member and the magnetic material constituting the face plate portion, the non-magnetic member may protrude or retract from the outer surface of the face plate portion, resulting in long-term use. As a result, irregularities are likely to occur on the suction surface, which serves as a processing reference surface. Therefore, the conventional magnetic chuck has the disadvantage that the flatness of the attracting surface cannot be maintained for a long period of time.

In particular, in a magnetic chuck that uses an electromagnetic device having an excitation coil as the magnetic source, this electromagnetic device becomes a heat generation source, so it is strongly affected by the difference in the thermal expansion coefficients mentioned above. The magnetic chuck used is particularly susceptible to unevenness on the attraction surface.

(Objective) Therefore, an object of the present invention is to provide a magnetic chuck that can maintain a high degree of flatness on its suction surface even after long-term use.

(Structure) The present invention is characterized in that grooves for magnetically dividing the face plate portion of the housing into magnetic pole portions of different magnetic poles are formed on the inner surface of the face plate, and the outer surface of the face plate portion is made a flat surface made of a single member. It is characterized by

(Operations and Effects) In the magnetic chuck of the present invention, the portion that defines the bottom surface of the groove, that is, the portion that connects the adjacent magnetic pole portions, is connected to the magnetic source as in the conventional magnetic chuck described above. magnetically saturated when a magnetic flux of Thereby, the outer surface of the face plate portion is brought into an excited state by the magnetic flux from the magnetic source, and acts as an attraction surface that attracts a workpiece made of a magnetic material.

In the magnetic chuck of the present invention, the face plate portion is magnetically divided into magnetic pole portions of different magnetic poles by the grooves formed on the inner surface of the face plate portion, so that the attracting surface serving as the processing reference surface of the magnetic chuck is The outer surface of the face plate portion that defines the suction surface is made a flat surface made of a single member, without requiring a conventional groove for magnetically dividing the face plate portion on the outer surface of the face plate portion that defines the attraction surface. In addition to this, it is possible to obtain highly accurate flatness on the suction surface, and also because a non-magnetic member made of a different material from the face plate portion is not exposed on the outer surface, that is, the suction surface. The adsorption surface can be made to have a uniform hardness. Therefore, uneven wear due to the difference in hardness of the materials as described above does not occur on the adsorption surface, and the non-magnetic member makes it possible to make the adsorption surface have a uniform hardness. No unevenness occurs on the surface, and the flatness of the suction surface can be maintained for a long period of time.

Further, even if the groove formed on the inner surface of the face plate portion is filled with a non-magnetic material such as synthetic resin for reinforcement etc., the non-magnetic material does not participate in the formation of the attracting surface. Even if the non-magnetic material protrudes or retracts from the inner surface of the face plate portion due to the difference in coefficient of thermal expansion, this will not cause unevenness on the attraction surface.

Further, since the suction surface is defined only by the flat outer surface of the face plate portion, it is relatively easy to apply the suction surface to the outer surface of the face plate portion made of a single member in order to harden the suction surface. A hardening treatment can be performed to uniformly harden the suction surface defined by the outer surface of the face plate portion, thereby preventing wear and damage of the suction surface and improving the suction surface. The flatness of the area can be maintained for a longer period of time.

As described above, according to the present invention, the groove is open to the inner surface of the face plate portion, and the outer surface of the face plate portion is a flat surface defined by a single member. Uneven wear does not occur on the suction surface, and unevenness caused by the non-magnetic member is not formed on the suction surface, so that the flatness of the suction surface is maintained over a long period of time. .

(Example) The features of the present invention will become clearer from the following description of the illustrated embodiment.

1 and 2 show an embodiment in which the present invention is applied to a round magnetic chuck 10. FIG. Magnetic chuck 10, as shown in FIG. 1, includes a housing 12 and a plurality of excitation coils 14 contained within the housing. Housing 12 includes a generally circular housing body 16 made of magnetic material.
and a circular bottom plate 18 made of a magnetic material.

The housing body 16 includes a face plate portion 20 having a circular flat plate shape as a whole, and a flat inner surface 2 facing a lower surface 20a of the face plate portion, that is, a bottom plate 18 of the face plate portion 20.
A plurality of annular partition walls 2 extending from 0a to the bottom plate 18
2 and 24. The outermost partition wall portion 22 constitutes the outer peripheral wall of the housing 12 .
The partition wall portions 22 and 24 are arranged concentrically and spaced apart from each other. The excitation coil 14 is disposed within an annular chamber 26 defined between adjacent partition wall portions. As is well known in the art, the partition wall portion 24 acts as a magnetic core for each excitation coil 14, and the core together with the excitation coil 14 constitutes an electromagnetic device serving as a magnetic source.

In the embodiment shown in FIG.
4 is formed integrally with the face plate portion 20, but the partition wall portions 22 and 24 can be divided from the face plate portion 20 and formed integrally with the bottom plate 18.

The outer surface 20b of the face plate portion 20, that is, the flat outer surface 20b of the face plate portion 20 located on the opposite side from the inner surface 20a described above, is configured to allow a workpiece (not shown) made of a magnetic material to be moved by the magnetic force of the magnetic source. It becomes an adsorption surface for adsorption. The flat inner surface 20a of the face plate portion 20 has a plurality of annular grooves 2 open thereto.
8 are formed concentrically with each other. The groove 28 is
It is arranged so as to divide the face plate portion 20 into portions corresponding to the partition walls 22 and 24, and does not reach the outer surface of the face plate portion 20, that is, the suction surface 20b. The suction surface 20b of the face plate portion 20 is hardened to a depth approximately equal to the bottom level of the groove 28 by hardening treatment such as induction hardening or flame hardening.

In the example shown in FIG.
For example, an epoxy resin filled in the chamber 26 to position the 4 in the corresponding chamber 26,
Although filled with a preferably flexible non-magnetic material 30 such as polyester or urethane resin, the groove 28 can be left blank without being filled with the non-magnetic material 30 described above.

A portion defining the bottom surface of the groove 28, that is, a portion connecting the adjacent magnetic pole portions becomes a leakage magnetic path of the magnetic flux generated by the excitation coil 14. but,
The portion has a thickness dimension that magnetically saturates when the magnetic flux acts on the portion, as in the conventional magnetic chuck described above. When the portion is magnetically saturated, magnetic flux that cannot pass through the portion inevitably appears on the attraction surface 20b.
The face plate portion 20 is a partition wall portion 2 that acts as a magnetic core.
2 and 24 are magnetically divided by grooves 28, the attracting surface 20b is placed in an excited state, and the workpiece made of a magnetic material is placed in the attracting surface 20b.
It is adsorbed by b.

The excitation coil 14 is excited by energization, and by this energization, the portion of the face plate portion 20 corresponding to the outermost partition wall portion 22 is magnetized, for example, to the N pole, and the partition wall portion 24 located inside thereof is magnetized. When the corresponding portions are sequentially and alternately magnetized to be S and N poles, the grooves 28 substantially prevent the generation of leakage magnetic flux between adjacent different magnetic pole portions. Also,
When the excitation coil 14 is excited, the attraction surface 20b of the face plate portion 20 has a ring-shaped different magnetic pole portion clearly formed therein, as clearly shown in FIG. The workpiece can be reliably fixed by the applied magnetic force.

In the magnetic chuck 10, the face plate portion 20 defining the suction surface 20b for the workpiece is connected to the inner surface 20 of the magnetic chuck 10.
Since it is magnetically divided into different magnetic pole parts by the groove 28 formed in the outer surface 20 which is the attracting surface.
The attraction surface 20b can be magnetically divided into different magnetic pole parts without exposing a non-magnetic member as in the conventional case.
0 can be constructed from a single magnetic member. Therefore, it is possible to obtain highly accurate flatness on the suction surface 20b, which serves as a reference surface for machining the workpiece, and moreover, there is no local hardness difference caused by material differences on the suction surface 20b.
Since the hardness of the suction surface 20b can be made uniform, local wear due to the hardness difference described above does not occur on the suction surface 20b, and the flatness of the suction surface 20b is maintained over a long period of time.

Further, the non-magnetic member made of a material different from that of the face plate portion 20 is not exposed to the attraction surface 20b, and the non-magnetic material 30 filled in the groove 28 of the inner surface 20a of the face plate portion 20 takes part in the formation of the attraction surface 20b. Therefore, even if the non-magnetic material 30 protrudes or retracts from the inner surface 20a of the face plate portion 20 due to the difference in coefficient of thermal expansion, this will not cause unevenness on the attracting surface 20b, and therefore the flatness of the attracting surface 20b will not change. is maintained over a long period of time.

Furthermore, since the non-magnetic member is not exposed on the attracting surface 20b, the attracting surface 20b can be hardened relatively easily.
Uniform hardening can be achieved, wear and damage to the suction surface 20b can be prevented, and the flatness of the suction surface 20b can be maintained for a longer period of time.

3 and 4 show an embodiment in which the present invention is applied to a rectangular magnetic chuck 10' in which the magnetic source is a permanent magnet assembly. The magnetic chuck 10' includes a generally rectangular housing 12' made of magnetic material;
a permanent magnet assembly 14' slidably disposed within the housing. As is well known in the art, the housing 12' is divided into a rectangular housing body portion 16' with an open top end and a flat face plate portion 20' that closes the open end of the housing body portion 16'.

As is well known in the art, the magnet assembly 14' includes a plurality of permanent magnets 34 that are integrally coupled with the same magnetic pole faces facing each other and with a magnetic pole member 32 interposed therebetween. The permanent magnets 34 are arranged such that the magnetic pole members 32 alternately have different magnetic poles in the order of arrangement.
The magnetization direction is alternated in the order of arrangement. The magnetic pole member 32 is located between the energized position shown in FIG. 3 showing the energized state and the demagnetized position shown in FIG. 4 illustrating the demagnetized state.
While in contact with a', it is slidable in the longitudinal direction of the housing 12', that is, in the direction in which the magnetic pole members 32 are arranged.

Linear grooves 28' are formed in the inner surface 20a' of the face plate portion 20' at intervals in the longitudinal direction of the housing 12' and extend in the width direction of the housing 12'.
As in the examples shown in FIGS. 1 and 2, each groove 28' does not reach the flat upper surface defining the attraction surface of the magnetic chuck 10', that is, the outer surface 20b', but the inner surface described above. Open to 20a'.

The portion that defines the bottom surface of the groove 28', that is, the portion that connects the adjacent magnetic pole portions, is located in the magnet assembly 1.
When 4' is in the energized position, it becomes a leakage magnetic path for the magnetic flux generated by the magnet assembly 14'. However, as in the conventional magnetic chuck described above and the magnetic chuck 10 described above, the region has a thickness dimension that magnetically saturates when the magnetic flux acts on the region. Therefore, the face plate portion 20' is
Grooves 28' allow each pole member 32 in the energized position to
It is magnetically divided into magnetic pole parts corresponding to .

When the magnet assembly 14' is in the excitation position, leakage magnetic flux is substantially prevented from occurring between adjacent different magnetic pole parts, and the outer surface of the face plate part 20', that is, the attracting surface 20b' forms a linear different magnetic pole part. Since it is clearly divided, the workpiece can be reliably fixed by the magnetic force acting on this attraction surface 20b'.

In the magnetic chuck 10', as in the magnetic chuck 10 described above, the attraction surface 20b' is not exposed to the attraction surface 20b' without exposing the non-magnetic member as in the conventional case.
0b' can be magnetically divided into different magnetic pole parts,
As a result, the suction surface 20b' can be composed of a single magnetic member constituting the face plate portion 20'.
0b', and a non-magnetic member made of a different material from the face plate portion 20' is not exposed on the attracting surface 20b', and the flatness of the attracting surface can be maintained over a long period of time. Can be maintained.

To strengthen the faceplate portion 20', the groove 28' can be filled with a non-magnetic material as described above. In addition, since the non-magnetic member is not exposed on the suction surface 20', the suction surface 20b' can be easily hardened.
b′ can be uniformly cured, and the suction surface 20
The flatness of b′ can be maintained with high accuracy for a longer period of time.

In the above description, a chuck using a permanent magnet assembly or an electromagnetic device as a magnetic source has been described, but the present invention can be applied to a chuck using a combination of a permanent magnet and an electromagnetic device as a magnetic source. Furthermore, the grooves can be formed in various shapes on the lower surface, that is, the inner surface, of the face plate portion in order to divide the upper surface, that is, the outer surface, of the face plate portion into magnetic pole parts of various shapes.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a round magnetic chuck according to the present invention, FIG. 2 is a plan view of the magnetic chuck shown in FIG. 1, and FIGS. FIG. 3 is a vertical cross-sectional view showing a square magnetic chuck according to an embodiment of the present invention in an excited state and a demagnetized state, respectively. 10, 10': chuck, 12, 12': housing, 14, 14': magnetic source, 20, 20': face plate portion, 20a, 20a': inner surface, 20b, 20b':
Outer surface (adsorption surface), 28, 28': groove, 30: synthetic resin material.

Claims (1)

[Scope of Claims] 1. A magnetic chuck comprising a housing that houses a magnetic source and is provided with a face plate portion that is excited to attract a magnetic material by the magnetic force of the magnetic source, wherein the face plate portion is magnetically divided into magnetic pole parts of different magnetic poles by grooves opened on the inner surface of the face plate part, and the outer surface of the face plate part is a flat surface defined by a single member. Check. 2. The magnetic chuck according to claim 1, wherein the outer surface of the face plate portion is hardened by quenching. 3. The magnetic chuck according to claim 1, wherein the groove is filled with a non-magnetic synthetic resin material. 4. The magnetic chuck according to claim 1, wherein the magnetic source comprises an electromagnetic device having an excitation coil.