JPH054143A - Magnet chuck - Google Patents

Abstract

PURPOSE:To provide a magnet chuck for a work to be processed, with separate controllability for the magnetization force to a backing plate and the pressing force to a shoe. CONSTITUTION:A front rotary shaft 2 and a backing plate 4 are formed from a plurality magnetic substances 7, 8 by a spacer 6 and center shaft 5 made of non-magnetic substance, and the magnetic flux due to an electric magnet 10 is allowed to pass only between the backing plate 4 and a work to be processed A. An independent electric magnet 15 is furnished between shoes 13, 14, and a force to attract the work A to them is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnet chuck that supports a rotating workpiece such as a grinding process.

[0002]

2. Description of the Related Art FIGS. 7 (a) and 7 (b) show the structure of a magnet chuck used for supporting a workpiece in a conventional grinding process.

As shown in the figure, the rotary shaft 71 is composed of a rear rotary shaft 72 made of a non-magnetic material and a front rotary shaft 73 made of a magnetic material. A magnet is provided on the peripheral surface of the front rotary shaft 73. 74 are arranged opposite to each other without contact. A backing plate 76 made of a magnetic material is attached to the end of the front rotary shaft 73.
The workpiece A to be ground by the grinding wheel B is in contact with the end surface of the workpiece.

The outer peripheral surface of the work A is rotatably supported by shoes 78 and 79 attached to a shoe bracket 77, and a flux guide 81 attached to the shoe bracket 77 abuts a housing 80 of a magnet 74. ing.

In the above structure, when the front rotating shaft 73 is magnetized by the magnet 74, the backing plate 76, the work A, and the shoes 78, 7 from the tip of the front rotating shaft 73.
9, a magnetic circuit connecting the shoe bracket 77 and the flux guide 81 is formed, and an attractive force is generated between the backing plate 76 and the work A, and between the work A and the shoes 78 and 79, and the work A is chucked. It

[0006]

By the way, in the above-mentioned magnet chuck, in order to prevent the workpiece A from rotating due to the grinding force and from being hung around by the grindstone B, the magnetic force of the backing plate 76 is set. Strengthen to increase the driving force of the workpiece,
Shoes 78, 7 that act to stop the rotation of workpiece A
It is necessary to control the attraction force of 9 appropriately.

For this reason, conventionally, the chucking force between the backing plate and the shoe is changed by variously changing the current value to the magnet, the material and shape of the shoe, the material and shape of the backing plate, etc., depending on the target workpiece. However, such a method requires a great deal of time and effort to select the conditions, which deteriorates the work efficiency and ensures that an appropriate workpiece chuck can be obtained. There was a problem that it was hard to be beaten.

Further, the work A is backed by the backing plate 76.
In order to increase the magnetizing force on the end face, it is possible to increase the current value flowing to the magnet 74 and increase the magnetic flux density passing through the backing plate 76. , 79
Since they are connected by the same magnetic circuit, when the current value to the magnet is increased, the magnetic flux density between the workpiece and the shoe also increases, and the pressing force on the shoe also increases at the same time. For this reason, only the magnetic force of the backing plate 76 cannot be increased freely, and it is difficult to control the driving force for the workpiece.

Therefore, an object of the present invention is to provide a magnet chuck capable of freely changing the magnetic force of the backing plate and appropriately controlling the chucking force on a workpiece.

[0010]

In order to solve the above-mentioned problems, the first means of the present invention is to divide the end surface of the backing plate into a plurality of magnetic surfaces by a non-magnetic material, The different magnetic poles are magnetized by the magnets arranged on the peripheral surface of the rotating shaft.

In addition to the above structure, the second means of the present invention employs a structure in which a magnet independent of the magnet of the rotary shaft is opposed to the outer periphery of the workpiece.

[0012]

In the above-mentioned first means, since the magnetic pole surface of the opposite pole is formed on the end surface of the backing plate, the magnetic circuit is formed only between the backing plate and the workpiece without passing through the shoe and flows to the magnet. Only the magnetic force of the backing plate can be changed depending on the current value.

In the second means, a magnet independent of the above magnet can change the supporting force of the work piece with respect to the shoe irrespective of the magnetic force of the backing plate, thereby setting the optimum chuck state. be able to.

[0014]

Embodiments (a), (b) and (c) of FIG. 1 show a first embodiment. The rotary shaft 1 is formed of a front rotary shaft 2 and a rear rotary shaft 3, and a backing plate 4 is attached to an end of the front rotary shaft 2.

The front rotary shaft 2 and the backing plate 4
As shown in FIGS. 1 (b) and 1 (c), the outer surface of the central axis 5 is made of a non-magnetic material, and the spacer 6 made of a non-magnetic material is arranged on the peripheral surface of the central axis 5. The structure is divided by two magnetic materials 7, 7, 7, 7 and 8, 8, 8, 8. In the state where the front rotary shaft 2 and the backing plate 4 are attached, each ferromagnetic material 7, 8 The end faces of are set so as to touch each other.

On the other hand, the rear rotary shaft 3 is entirely made of a non-magnetic material so that the magnetic flux of the front rotary shaft 2 does not escape to the rear part.

The backing plate 4 is formed in a tapered shape so that the magnetic flux emitted from the front rotary shaft 2 can be easily converged toward the tip, and the work A is attached to the tip.
An end face 9 is formed which is perpendicular to the axis with which the a.

On the outer peripheral surface of the front rotary shaft 2, both ends 11a and 11b of an iron core 11 are arranged opposite to each other with a proper gap, and the iron core 11 and a chuck coil 12 wound around it. The electromagnetic magnet 10 is constituted by. In this electromagnetic magnet 10, the chuck coil 12
By passing a current to, one of the ends of the iron core 11 can be magnetized to the N pole and the other to the S pole.

Two shoes 13, which slidably contact the outer peripheral surface of the workpiece A, are provided below the front end of the backing plate 4.
14 is arranged, and an electromagnetic magnet 15 independent of the electromagnetic magnet 10 is installed between the shoes 13, 14. The magnet 15 includes an iron core 16 and a chuck coil 17, and one end 16 of the iron core 16 is provided.
a faces the outer peripheral surface of the workpiece A with a proper gap.

In the magnet chuck having the above structure, when the upper end 11a of the iron core 11 of the electromagnetic magnet 10 is magnetized to the N pole, the upper ferromagnetic material of the front rotary shaft 2 and the backing plate 4 is magnetized. One or two of 7, 8 are S poles, and one or two of the lower ferromagnetic materials 7, 8 are magnetized to N poles.

In this case, the magnetic flux flows from the upper end (N pole) 11a of the iron core to the front rotary shaft 2 as shown in FIG. 1 (a).
Upper surface of the backing plate → the upper surface of the backing plate 4 → the work A → the lower surface of the backing plate 4 → the lower surface of the front rotary shaft 2 and enters the lower end (S pole) 11b of the iron core 11. .

In this way, a magnetic circuit is formed between the end surface 9 of the backing plate 4 and the workpiece A, and the shoes 13, 1
4, the magnetic force between the backing plate 4 and the workpiece A can be changed by changing the current value of the electromagnetic magnet 10 to the chuck coil 12, and the chucking force on the workpiece A can be easily controlled. can do.

On the other hand, as described above, the magnetic circuit is the shoe 1
If the work pieces 3 and 14 are not passed, the force for pressing the work piece against the shoe is reduced, and the work piece A is easily lifted up by the grinding force or the like. This is due to the iron of the magnet 15 facing the work piece A. This is dealt with by magnetizing the end portion 16a of the core 16 to the N pole and generating a force between the iron core 16 and the lower surface of the workpiece A that is always magnetized to the S pole to attract the workpiece to the shoes 13 and 14. can do. In this case, by changing the current value of the magnet 15 to the chuck coil 17, the attraction force to the shoes 13 and 14 can be controlled regardless of the magnetic force of the backing plate 4, so that the workpiece A is lifted. You can easily find the conditions that do not cause it.

2A, 2B and 2C show a second embodiment. In this example, two electromagnetic magnets 22, 2 are provided on the outer circumference of the tip of the rotary shaft 21 made of a non-magnetic material.
3 are arranged so as to face each other, and the iron cores 24 and 25 of the electromagnetic magnets 22 and 23 are connected by a magnetic ring 26 that surrounds the rotating shaft 21.

The backing plate 27 has a central shaft 28 made of a non-magnetic material and a spacer 2 as in the first embodiment.
9 has a structure in which the outer peripheral surface is divided into four magnetic materials 30, but the end face 27a at the rear end is projected from the rotary shaft 21, and the end portions of the iron cores 24 and 25 of the electromagnetic magnets 22 and 23 are formed. They are facing each other with a suitable gap.

In the above structure, when the iron cores 24 and 25 of the electromagnetic magnets 22 and 23 are magnetized with the N pole and the S pole in opposite directions, the magnetic flux generates an end portion (N pole) of the upper iron core 24.
From the upper side of the backing plate 27 → the work A → the lower side of the backing plate 27 → the end of the iron core 25 on the lower side (S pole)
The iron core 2 on the upper side from the other end (N pole) of the iron core 25.
4 enters the other end (S pole).

As described above, the magnetic circuit of the electromagnetic magnets 22 and 23 passes through the backing plate 27 and the workpiece A,
Since it does not pass through the shoes 13 and 14, it is possible to individually control the magnetic attraction force of the workpiece to the backing plate and the force of pressing the workpiece against the shoe.

FIGS. 3A, 3B and 3C show the third embodiment. In this example, the front rotary shaft 31 has a magnetic material 32 extending from the rear side of the rotary shaft to the end face on the front side along the central axis, and a magnetic material 33 arranged on the outer peripheral side of the front side.
And the non-magnetic material 3 for separating the magnetic materials 32 and 33 from each other.
4 and the end portions 36a, 36b of the iron core 36 of the electromagnetic magnet 35 are arranged opposite to each other on the outer circumference of each magnetic material 32, 33.

The backing plate 37 is formed of a non-magnetic material 38 having a special shape as shown in FIGS. 4A, 4B and 4C and two magnetic materials 39 and 40, and The magnetic materials 39, 40 are attached to the back end surface 41 of the backing plate 37 by the magnetic materials 32, 33 of the front rotary shaft 31.
It is set so that the two magnetic surfaces 43 and 44 are formed by the front end surface 42 which contacts the workpiece A and the workpiece A.

Further, a power supply circuit (not shown) for alternately changing the direction of the current is connected to the chuck coil 49 of the electromagnetic magnet 47 arranged between the shoes 45 and 46, and the end of the iron core 48 has the N pole. And S pole are switched so that they can be magnetized.

In the above structure, when the upper end 36a of the iron core 36 of the electromagnetic magnet 35 is magnetized to the N pole, the magnetic flux causes the magnetic material 32 to pass from the rear side of the front rotary shaft 31 through the central portion to the next side. Then, the magnetic material 39 extends from the center of the backing plate 37 to the upper magnetic surface 43 of the front end face 42, and passes from the workpiece A to the magnetic material 44 on the outer circumference of the backing plate 37 and the magnetic material 40 on the outer circumference of the front rotary shaft 31. And enters the lower end 36b of the iron core 36 which is the S pole.

As described above, in the structure of this example, even if the front rotary shaft 31 rotates, the magnetic pole inside the rotary shaft does not rotate and is in a fixed state, so that hysteresis loss does not occur. On the other hand, in the structures of the first and second embodiments described above, the N-pole and the S-pole change with the rotation of the rotary shaft, so that hysteresis loss tends to occur.

Further, in the above structure, since the magnetic pole of the workpiece facing the electromagnetic magnet 47 changes as the workpiece A rotates, the N pole and the S pole of the end portion of the iron core 48 are synchronized with the rotation of the workpiece. Switch so that the pole that is different from the lower side of the work piece always faces the work piece side. As a result, the workpiece A
It is possible to constantly generate a force that presses the shoe against the shoes 45, 46, and it is possible to perform stable rotation of the workpiece.

5 (a), 5 (b) and 5 (c) show a fourth embodiment. This example is similar to the third embodiment described above,
The front rotary shaft 51 has the same structure as that of the third embodiment for the purpose of preventing the hysteresis loss due to the change of the magnetic poles. Further, the backing plate 52 is divided by the annular non-magnetic material 53 into the magnetic material 5 on the center side.
4 and the magnetic material 55 on the outer peripheral side, the magnetic poles of the front rotary shaft 51 and the backing plate 52 are always fixed even when the rotary shaft rotates.

In the above example, since the magnetic poles on the outer peripheral side of the work A are constant, the magnetic poles of the iron core 59 of the electromagnetic magnet 58 arranged between the shoes 56 and 57 are the same as those in the third embodiment. There is no need to change in synchronization with the rotation of the workpiece,
You can leave it constant.

FIGS. 6A and 6B show the fifth embodiment. In this example, the backing plate 6 has a structure similar to that of the second and fourth embodiments described above.
The magnetic material 63 on the outer peripheral side of 2 is projected in the radial direction from the peripheral surface of the front rotary shaft 61 formed of a magnetic material, and the magnetic material 63 is provided with the iron cores 67, 68 of the electromagnetic magnets 65, 66.
One ends of the two are opposed to each other. Further, flux guides 69, 69 connected to the front rotary shaft 61 are opposed to the other ends of the iron cores 67, 68 of the respective electromagnetic magnets 65, 66. In addition, you may provide three or more said electromagnetic magnets.

In the above structure, when the end portion of the iron core 67 facing the magnetic material 63 is magnetized to the N pole, the magnetic flux moves from the outer peripheral side of the backing plate 62 to the work A → the central side of the backing plate 62. Magnetic material 64 → front rotary shaft 61
Through the flux guides 69, 69 to enter the end portions of the iron cores 67, 68 which become the S poles.

[0038]

As described above, in the first means of the present invention, since the magnetic circuit by the magnet is formed between the backing plate and the workpiece without passing through the shoe, only the backing plate magnetizing force is unique. The optimum chucking force for the workpiece can be easily set.

In the second means, the force for pressing the work piece against the shoe can be controlled independently of the magnetic force of the work piece on the backing plate, so that the work piece can be reliably prevented from rising. It is possible to obtain a stable rotation state.

[Brief description of drawings]

FIG. 1A is a partially longitudinal front view of the first embodiment, and b is its b.
-Cross-sectional view taken along line b, c is a cross-sectional view taken along line cc

FIG. 2a is a partially longitudinal front view of the second embodiment, and b is its b.
-Cross-sectional view taken along line b, c is a cross-sectional view taken along line cc

FIG. 3A is a partially longitudinal front view of the third embodiment, and b is its b.
-Cross-sectional view taken along line b, c is a cross-sectional view taken along line cc

4A is a rear view of the backing plate of the third embodiment, FIG. 4B is a front view of the backing plate, and c is a sectional view taken along line cc of b.

5A is a partially longitudinal front view of the fourth embodiment, and b is its b.
-Cross-sectional view taken along line b, c is a cross-sectional view taken along line cc

FIG. 6A is a partially longitudinal front view of the fifth embodiment, and b is its b.
-Cross section along line b

7A is a front view of a conventional example, and b is a front view thereof.

[Explanation of symbols]

1, 21 rotary shafts 2, 31, 51, 61 front rotary shafts 4, 27, 37, 52, 62 backing plates 8, 30, 39, 40, 54, 55, 63, 64 magnetic material 9, 42 end face 10, 22, 23, 35, 65, 66 Electromagnetic magnet 13, 14, 45, 46, 56, 57 Shoe 15, 47, 58 Electromagnetic magnet A Workpiece

Claims (2)

[Claims] 1. A magnet chuck in which a backing plate is attached to a rotary shaft on which a magnet is arranged in a non-contact manner on a peripheral surface, and the outer circumference of a workpiece brought into contact with an end surface of the backing plate is supported by a shoe. A magnet chuck, characterized in that an end surface of a backing plate is divided into a plurality of magnetic surfaces by a non-magnetic material, and different magnetic poles are magnetized by the magnets on the plurality of magnetic surfaces. 2. The magnet chuck according to claim 1, wherein a magnet independent of the magnet of the rotating shaft is opposed to the outer periphery of the workpiece.