JPS638091Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a switchable permanent magnet holding device that holds or is held by a magnetic material, and is particularly used to support a measuring instrument such as a dial gauge. The present invention relates to a permanent magnet holding device suitable for a so-called magnet base.

In conventional magnet bases, a permanent magnet is rotatably housed within the lumen of a magnetic circuit block.
The magnetically active surface of the block can be placed in the energized state by rotating the block from a non-excited rotational position in which the magnetically active surface is in a demagnetized state to an energized rotational position that is in an angular relationship of about 90 degrees. In the above-mentioned energized rotational position, the magnetic circuit block is almost in a magnetic equilibrium state as in the non-excited rotational position, so the permanent magnet is not subjected to strong magnetic rotational force between it and the magnetic circuit block. As a result, the permanent magnet in the excitation rotational position is held in that rotational position and exerts its maximum magnetic force on the magnetically active surface of the magnetic circuit block.

Therefore, the permanent magnet is placed between the non-energized rotational position and the approximately
By operating the magnetic base to the excitation rotation position that is at an angle of 90 degrees, the magnetic base can be firmly fixed to a surface plate made of a magnetic material by magnetic force. It can firmly support measuring instruments such as dial gauges.

By the way, when trying to measure the parallelism, flatness, straightness, etc. of a mechanical part or each part of a product, it is necessary to slide the measuring instrument supported by the magnetic base on the surface plate integrally with the magnetic base. Occurs often. In order to slide the magnetic base on the surface plate, in the conventional magnetic base, it is necessary to operate the permanent magnet to a non-energized rotational position and to place the magnetically active surface of the magnetic circuit block in a demagnetized state. However, when the magnetic base is slid in this demagnetized state, the magnetic base bounces or vibrates during sliding, making it difficult to slide smoothly, which tends to cause errors in the measurements described above. . In order to prevent the measurement error, it is desirable to maintain a weak magnetic force on the magnetically active surface so as not to prevent the sliding of the magnetic block.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a permanent magnet holding device capable of switching the magnetic force of the magnetically active surface of a magnetic circuit block to a predetermined value smaller than the maximum capacity value.

In the present invention, when a permanent magnet rotatably housed in a magnetic circuit block is rotated from a non-excited rotational position to an energized rotational position that is in an angular relationship of about 90 degrees, the rotation angle increases. It should be noted that the magnetic force of the magnetically active surface of the magnetic circuit block increases in response to the excitation rotational position, and the magnetic force of the magnetically active surface reaches its maximum capacity in the excitation rotational position, and the magnetic force acting on the permanent magnet is overcome and the A positioning means for holding the permanent magnet at a predetermined rotational position between the non-excitation rotational position and the excitation rotational position is arranged between the permanent magnet or a part that rotates integrally therewith and the magnetic circuit block. It is characterized in that the magnetic force of the magnetically acting surface can be adjusted by providing the magnetic field between the magnetically active surfaces.

The features of the invention will become clearer from the following description of the illustrated embodiment.

As shown in FIG. 1, a permanent magnet holding device 10 according to the present invention comprises a magnetic circuit comprising a non-magnetic plate 12 and a pair of magnetic pole members 14 integrally coupled with the non-magnetic plate interposed therebetween. The magnetic circuit block 16 includes a permanent magnet 20 disposed within a bore 18 formed in the magnetic circuit block.

The lumen 18 extends along and across the non-magnetic plate 12, as is well known in the art. The lumen 18 has a circular cross section and opens into one end of the magnetic circuit block 16.

The permanent magnet 20 housed within the lumen 18 has an overall cylindrical shape and is magnetized in its diameter direction. This permanent magnet 20 may be a ferrite magnet with a small reversible magnetic permeability (1.05 to 1.15), a rare earth metal magnet, or a large reversible magnetic permeability (2.5 to 4.0).
An alnico magnet having the following properties can be used.

The permanent magnet 20 is rotatable on the central axis of the lumen 18 and has an end 20 corresponding to the open end of the lumen.
It is connected to the operation knob 22 at a. Operation knob 2
2 includes a connecting portion 26 in which a recess 24 that fits into the end portion 20a of the permanent magnet 20 is formed, and a connecting portion 26 extending outward from the magnetic circuit block 16 along the rotation axis of the permanent magnet 20. A lever 30 is provided on the shaft to facilitate rotational operation.
is fixed. The shaft 28 passes through an end plate 32 which is secured to the open end of the bore 18 of the magnetic circuit block 16 to close it.

The permanent magnet 20 has a first magnetization direction aligned with the non-magnetic plate 12 when viewed from the open end of the inner cavity 18.
In the non-energized rotational position shown, the magnetically active surface 14a of the magnetic circuit block 16 is placed in a demagnetized state, as is well known in the art.

Furthermore, in an energized rotational position that is at an angle of about 90 degrees from the non-excited rotational position, the permanent magnet 20 places the magnetically active surface 14a in an energized state at its maximum capacity, as is well known in the art.

The graph shown in FIG. 2 shows that the permanent magnet 20
The relationship between the rotation angle θ from the non-excited rotational position to the excitation rotational position and the magnetic attraction force, that is, the magnetic force F of the magnetically acting surface 14a, is shown by the horizontal and vertical axes, respectively. The line indicated by the symbol A in the graph represents the characteristics when a ferrite magnet with a small reversible magnetic permeability is used as the permanent magnet 20, and the line indicated by the symbol B represents the characteristics when an alnico magnet with a large reversible magnetic permeability is used as the permanent magnet 20. This shows the characteristics when using . As is clear from both characteristic lines A and B, the rotation angle changes from the non-excited rotation position where the rotation angle is 0 degrees.
As the rotation angle of the permanent magnet 20 increases toward the excitation rotational position of 90 degrees, the magnetically active surface 14a
The magnetic force F increases, and the magnetically active surface 14a exerts the maximum magnetic force at the excitation rotational position.

As is clear from the graph, by holding the permanent magnet 20 at a rotational position between the non-excited rotational position and the excitation rotational position (0° < θ < 90°), the The magnetic force of the magnetically acting surface 14a can be reduced below the maximum value.

By the way, the permanent magnet 20 in the non-excited rotational position and the excitation rotational position is connected to the magnetic circuit block 1.
Since the magnetic circuit block 6 is placed in a magnetically balanced state, it does not receive any magnetic rotational force between it and the magnetic circuit block. However, the permanent magnet 20 located between the two rotational positions is subjected to a strong magnetic rotational force toward the non-excited rotational position, since this disturbs the equilibrium state of the magnetic circuit block. Because of this magnetic rotational force, even if the operator operates the permanent magnet 20 to a desired intermediate rotational position between the two rotational positions, the operating knob 22
When the hand is released, the permanent magnet 20 returns to the non-excited rotational position, resulting in the magnetically active surface 14a being demagnetized.

Positioning means is provided between the magnetic circuit block 16 and the permanent magnet 20 in order to overcome the magnetic rotational force and hold the permanent magnet 20 at a desired intermediate rotational position. The positioning means includes:
As shown in FIG. 1, a plurality of tooth grooves 34, 34a-- are formed along the circumferential direction on the outer peripheral surface of the connecting portion 26 of the operating knob 22, which is rotatable integrally with the permanent magnet 20. 34d and a ball 36 cooperating with the tooth groove.

The tooth grooves 34, 34a to 34d extend over an angular range of approximately 90 degrees of the connecting portion 26, corresponding to the rotation angle from the non-excited rotational position (0°) to the energized rotational position (90°). They are arranged continuously in the circumferential direction. Therefore, the tooth spaces 34a and 34d on both sides
correspond to the non-excited rotational position and the excitation rotational position, respectively, and the tooth groove 34 between the tooth grooves 34a and 34d
b and 34c correspond to different predetermined rotational positions between the non-excitation rotational position and the excitation rotational position, respectively.

Instead of providing a plurality of tooth spaces 34a-34d, a single recess 34 for receiving the ball 36 can be provided at a desired location corresponding to the non-energized rotational position and the energized rotational position.

In order to support the ball 36, one of the pole members 14 has a lumen 18 near the open end thereof.
The inner cavity 18 faces the tooth groove group 34 of the connecting portion 26.
A hole 38 is formed with one end closed and open to the other end.
A coil spring 40 for pressing the ball 36 against the tooth space group 34 is arranged in the hole 38 .
Thereby, the ball 36 is elastically supported so as to be able to protrude from the inner cavity 18, that is, to be able to engage with the tooth groove group 34.

The engagement between the ball 36 and the tooth groove 34a defines the non-excited rotational position (0°), and the magnetically active surface 14a is placed in a demagnetized state. When the operation knob 22 is rotated by overcoming the pressing force of the spring 40, the ball 36 moves into the tooth space 3 according to the rotation angle.
4b or 34c. In this engaged state, the permanent magnet 20 receives a magnetic rotational force toward the non-excited rotational position according to its rotation angle. However, due to the engagement between the ball 36 that receives the elastic force of the spring 40 and the tooth groove 34b or 34c that engages with the ball 36, the permanent magnet 20 is reliably positioned at the rotation angle defined by the tooth groove. Therefore, depending on the rotation angle, the magnetically active surface 1
4a, as is clear from the graph in Figure 2,
A magnetic force having a smaller value than the magnetic force at the excitation rotational position defined by the engagement between the ball 36 and the tooth groove 34d is excited.

Therefore, according to the magnet holding device 10, the above-mentioned measurement target, which is well known in the art, can be measured by a measuring instrument such as a dial gauge supported via a support (not shown) attached to the device. When trying to measure the parallelism, flatness and straightness of an object, the magnetic force of the magnetically active surface 14a is reduced,
This reduced magnetic force allows for smooth sliding on the base plate and the like, allowing accurate measurements to be made.

As shown in FIG.
A flange portion 42 is provided facing the edge of the open end of the inner cavity 18, and a tooth groove group 34 similar to that described above is formed on the surface of the flange facing the open end. A hole 38 that opens at the end surface is formed, and the coil spring 4 is disposed within the hole.
0 causes the ball 36 to be engaged with and pressed toward the tooth groove group 34, thereby forming a positioning means similar to that described above.

Further, as shown in FIG. 4, a tooth groove group 34 similar to that described above is formed on the edge of the open end of the inner cavity 18 of the magnetic circuit block 16, and A single protrusion 36' made of a spring plate capable of engaging with the tooth groove group 34 is formed on the surface facing the open end, and the two can constitute a positioning means similar to that described above.

In the above description, an example has been described in which the positioning means is provided between the operating knob 22 that rotates integrally with the permanent magnet 20 and the magnetic circuit block. By providing the above-mentioned tooth groove group on the magnetic pole member 14 and providing the ball 36, the hole 38 and the coil spring 40 as shown in FIG. Such a positioning means can be constructed directly. However, in this case, the volume of the permanent magnet 20 decreases due to the formation of the tooth groove group, and the amount of magnetic flux of the permanent magnet decreases. It is desirable that the positioning means be provided between the rotating operation knob 22 and the magnetic circuit block 16.

Furthermore, as is clear from the graph shown in FIG. 2, the rising slope of the magnetic force F of the magnetically acting surface 14a as the rotation angle θ increases is higher than the reversible magnetic permeability compared to the characteristic B of the alnico magnet. The characteristic A of the small ferrite magnet is gentler. This means that when defining a specific rotation angle of the permanent magnet 20 by the positioning means in order to obtain a desired magnetic force,
This means that it is advantageous to use a permanent magnet having a low reversible magnetic permeability, such as a ferrite magnet, because the desired magnetic force can be obtained more accurately.

According to the present invention, as described above, the magnetic force of the magnetically active surface of the magnetic circuit block can be switched to a value smaller than its maximum capacity value, as necessary, and thereby the magnetic force suitable for various usage modes can be changed. Holding power can be exerted.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of the permanent magnet holding device according to the present invention, FIG. 2 is a graph showing changes in magnetic force with respect to the rotation angle of the permanent magnet shown in FIG. 1, and FIG. and FIG. 4 are views similar to FIG. 1 showing other embodiments of the present invention. 14a: Magnetic action surface, 16: Magnetic circuit block, 18: Inner cavity, 20: Permanent magnet, 34, 34
b, 34c, 36, 36', 38: positioning means.

Claims (1)

[Claims for Utility Model Registration] (1) A magnetic circuit block having a magnetically active surface and a lumen, and a magnetic circuit block rotatably disposed on the central axis of the lumen, for placing the magnetically active surface in an energized or demagnetized state. In order to adjust the magnetic force of the rotating permanent magnet and the magnetically acting surface between the permanent magnet and the magnetic circuit block, the permanent magnet is moved to an excitation rotational position by overcoming the magnetic rotational force acting on the permanent magnet. and positioning means for holding the magnet in a predetermined rotational position between non-energized rotational positions. (2) The permanent magnet holding device according to claim (1), wherein the permanent magnet is made of a magnetic material having low reversible magnetic permeability. (3) The positioning means defines a plurality of predetermined rotational positions for the permanent magnet between the energized rotational position and the non-energized rotational position. Magnet holding device.