JP2021132175A - Magnetization device - Google Patents

Abstract

To provide a magnetization device which is magnetized to one part of a small diameter wire of a stainless steel whose diameter is 1.5 mm or less in a longitudinal direction.SOLUTION: A magnetization device comprises: a magnetization yoke 10 magnetizing a workpiece made of a power supply part generating a constant current and a magnetic body; and a controller controlling a temperature of an electromagnetic coil 12 of the magnetization yoke. The workpiece has a diameter of 0.1 to 1.5 mm and a length of 100 mm or larger. The length of a magnet part to be saturated and magnetized is 1 to 8 mm. The magnetization yoke is made of a bobbin 11 and the electromagnetic coil. The bobbin comprises a hollow pipe of an inner diameter of 0.3 to 2.0 mm. The electromagnetic coil is formed by an enamel wire of a diameter of 10 to 50 μm with a coil width of 1 to 8.4 mm so as to be turned in 500 to 3,000 times with a winding wire density of 400 times/mm or more. In addition, the magnetization yoke comprises two magnetic field distribution shapers made of a permanent magnet ring 141 magnetized in an axial direction of the bobbin on both outer sides of the bobbin and a yoke component 142 surrounding them.SELECTED DRAWING: Figure 7

Description

The present invention relates to a magnetizing device that magnetizes a part of a small-diameter wire made of hard magnetic stainless steel in the longitudinal direction into a magnet.

Stainless steel is the most basic material for medical devices and members used in the body from the viewpoint of biocompatibility in the medical field.
In recent years, advanced medical technologies such as magnetic treatment and robot treatment have been advanced, and research is being conducted on the utilization of magnetic performance by incorporating magnets in medical devices and members. However, the built-in magnet has the problem that the equipment becomes large, the problem that a complicated shield structure is required to shield the magnet, and the problem that the shield structure is damaged and the magnet is corroded. Measures are required.

The stainless steel used in the living body is an austenitic stainless steel having a Cr—Ni composition having excellent corrosion resistance and is non-magnetic. However, the austenite structure is forward-stable, and when cold working is applied, it causes martensitic transformation and becomes a hard magnetic stainless steel with a two-phase structure of ferromagnetic martensite structure and austenite structure (Non-Patent Document 1). Are known.

According to a study on magnetic properties after cold working, it has been confirmed that non-magnetic properties change to hard magnetic properties (Non-Patent Document 2). However, since its hard magnetic properties have a small coercive force to be used as a magnet, there is no application example of using stainless steel after cold working as a magnet, and research on its magnetizing device and magnetizing method is also carried out. There is no example.

In particular, there is no case where only a part of the hard magnetic stainless wire is saturated and magnetized and used as a magnet. Naturally, there is no research example on the magnetizing device and the magnetizing method for realizing such magnetizing.

As a result of keyword search (keyword: stainless steel * thin wire (wire) * magnetizing) by the patent document information retrieval system, no technical disclosure has been made regarding a magnetizing device for magnetizing a thin wire which is a small diameter wire of stainless steel.

Stainless Steel Handbook 4th Edition, pp. 58-60 Stainless Steel Handbook 4th Edition Page 113

In an austenitic stainless steel wire having a small diameter size of 1.5 mm or less and having a hard magnetism, a portion having a local length of 8 mm or less is saturated and magnetized in the longitudinal direction, and unsaturated deposition occurs at that time. Since the magnetized magnetized portion of the magnetic portion tends to decrease during use, it is necessary to make the length as small as possible. An object of the present invention is to make the length of the unsaturated magnetized portion 1 mm or less.

The present inventors have diligently studied the longitudinal saturation of a short portion of austenitic stainless steel having hard magnetism, which is a part of a long wire. The results are shown in FIGS. 1 to 3.
As shown in the example of the magnetization curve of FIG. 1, it was found that the magnetizing magnetic field strength needs to be 160,000 A / m or more in order to perform saturated magnetization. The exciting magnetic field H is generated by H = NI / L, is proportional to the number of coil turns and the pulse current I, and is inversely proportional to the length of the coil. The number of turns is 500 to 3,000 turns, the current strength is 0.4 A or more, the coil winding density (= N / L) is 400 times / mm or more, and a magnetic field of 160,000 A / m or more is generated. bottom. Here, it is desirable to increase the winding density of the coil as much as possible and reduce the current strength as much as possible.

As a result of research, when the wire diameter is 1.5 mm or less and the bobbin inner diameter is 2 mm or less, the saturated magnetized part of the wire is almost equal to the bobbin length if the bobbin inner diameter D is twice or less the wire diameter d. Specifically, it was found that it can be increased from 0.9 to 1.1 times.

FIG. 2 shows the relationship between the length l of the saturated magnetized portion, the inner diameter of the bobbin, and the relative ratio D / d of the wire diameter. It has been found that the length of the unsaturated magnetized portion Δl becomes smaller as the relative ratio D / d is made smaller, and can be made 1 mm or less at D / d = 2 or less.
Furthermore, they have found that the length of the unsaturated portion can be reduced to 0.5 mm or less by utilizing a magnetic field distribution shaper.
Here, the definitions of the saturated magnetized portion l and the unsaturated magnetized portion Δl will be described with reference to FIG. 3 showing the state of the magnetic permeability of the saturated magnetizing in the length direction of the wire.
The saturated magnetizing portion l refers to a portion of the magnetized wire having a magnetizing rate of 90% or more. The unsaturated magnetized portion Δl refers to a portion of a wire having a magnetizing rate of 10% or more and less than 90%.

Based on the above new findings, the present invention is a magnetizing device including a magnetizing yoke that magnetizes a workpiece composed of a power supply unit that generates a constant current and a magnetic material, and a controller that controls the temperature of the coil of the magnetizing yoke. hand,
The work has a diameter d of 0.1 to 1.5 mm, a length of 100 mm or more, and a saturated magnetized magnet portion (referred to as a saturated magnetized portion) having a length l of 1 to 8 mm.
The magnetizing yoke includes a bobbin and an electromagnetic coil that winds the bobbin. The width L of the electromagnetic coil is 1 to 8.4 mm, and L / l is 0. Consists of 9-1.1
The bobbin is provided with a brim at both ends and a hollow pipe for inserting the work, and the bobbin inner diameter D is 0.3 to 2.0 mm and the D / d is 1 to 2 or less.
The coil consists of an enamel wire with a diameter of 10 to 50 μm with 500 to 3,000 turns and a winding density of 400 times / mm or more.
The length Δl of the unsaturated magnetized portions on both sides of the saturated magnetized portion is 1 mm, respectively.

Further, in the case of continuous magnetizing operation, coil heat generation becomes a problem, and as a countermeasure, the power supply unit is characterized by applying a pulse current having a current intensity of 0.4 A or more and a pulse energizing time of 0.1 msec to 20 seconds. ..

Further, the magnetizing yoke is provided with two magnetic field distribution shapers on both outer sides of the brim of the bobbin, which consist of a permanent magnet ring magnetized in the direction of the bobbin magnetic domain and a yoke component consisting of a component surrounding the ring, and an electromagnetic coil is provided. It is characterized in that the spread of the magnetic field distribution to be formed is sealed inside the magnetic field distribution shaper.

According to the present invention, a part of a small-diameter wire made of hard magnetic stainless steel can be saturated and magnetized in the longitudinal direction, and a wire portion having substantially the same length as the bobbin can be made into a magnet. Further, the unsaturated magnetized portions on both sides of the magnet portion can be set to 0.5 mm or less.

It is a figure which shows the magnetization curve. It is a figure which shows the influence of the bobbin inner diameter and the magnetic field distribution shaper on the length of an unsaturated magnetized part. It is a figure which shows the unsaturated magnetized part. It is a figure which shows the circuit structure. It is sectional drawing of the magnetic yoke in Embodiment 1. FIG. It is a conceptual diagram of the magnetization state in Embodiment 1. FIG. 5 is a cross-sectional view of a magnetic yoke with a magnetic field distribution shaper according to the second embodiment. It is sectional drawing of A1-A2 in Embodiment 2. FIG. It is a conceptual diagram of the magnetization state in Embodiment 2. It is a figure which shows the magnetic field strength in the length direction of a wire.

Embodiments of the present invention are as follows.
The magnetizing device includes a power supply unit, a magnetizing yoke, and a controller.
Further, as shown in FIG. 4, the circuit configuration of the magnetizing device consists of a power supply circuit unit in which the pulse oscillator generates a constant current by the power supplied from the power supply and an electromagnetic coil of the magnetizing yoke by energizing the constant current. A magnetic field (magnetic field) is generated from the magnet to magnetize the magnetized body (also called the magnetized part) that is a part of the work inserted into the hollow pipe of the magnetizing yoke, and the magnetized part of the magnetized body. In the process of becoming saturated magnetization, the saturation magnetization is delayed in proportion to the number of turns of the coil, and the heating temperature of the coil due to the pulse current is detected, and the controller controls the energization time of the pulse current.

The first embodiment will be described in detail with reference to FIGS. 5 and 6.
The pulse oscillator that generates a constant current in the power supply unit has a current intensity of 0.4 A or more, and can apply a pulse current having a pulse time of 0.1 msec to 20 seconds. Saturation magnetization is performed by adjusting the diameter of the work, the length of the magnetized portion, and the number of coil turns.

The work is an unmagnetized wire of magnetic austenitic stainless steel (SUS304, SUS316, etc.) having a diameter of 0.1 to 1.5 mm and a length of 1,000 mm or more, and is a magnetized object to be magnetized. The site (ferritic material) is a part of the wire and has a length of 1 to 8 mm.
Although austenitic stainless steel is originally non-magnetic, it can have hard magnetism by forming a processed martensite structure of 50 to 95% by cold working, and is a material to be magnetized.

FIG. 5 illustrates an axial cross section of the bobbin constituting the magnetizing yoke 10.
The magnetizing yoke 10 includes a bobbin 11 and a magnetizing coil 12 for winding the bobbin 11, the bobbin has brims 111 at both ends, and the bobbin body 112 has an inner diameter of 0 for inserting a work. A hollow pipe 113 (corresponding to the inner diameter D of the bobbin) having a thickness of 3 to 2.0 mm is provided.

The bobbin 11 is made of a non-magnetic material such as resin, ceramic, or non-magnetic steel. The total length of the bobbin is preferably 1 mm to 8.4 mm in consideration of the inner width of the bobbin around which the coil is wound so that the magnetized portion can be magnetized. The body diameter including the hollow pipe 113 is preferably 0.7 to 2.5 mm, the diameter of the brim 111 is preferably 1.5 to 8 mm, and the thickness is preferably 0.2 to 0.8 mm.

In the electromagnetic coil 12, an enamel wire having a diameter of 10 to 50 μm is wound around a body with a winding number of 500 to 3,000 turns and a winding density of 400 times / mm or more. In order to saturate the magnetized portion while preventing heat generation of the electromagnetic coil 12, it is necessary to suppress the pulse current I while increasing the magnetic field strength with the number of turns N of 500 turns or more. The excessive number of turns N is set to 3,000 turns because the coil size becomes large and heat is easily generated.
A temperature sensor 13 for detecting the heat generation temperature is provided. The temperature sensor 13 may be installed at the right end of the electromagnetic coil 12 as shown in FIG.

Further, the bobbin 11 is fixed to a bobbin stage (not shown) of the magnetizing device, and the work 30 inserted into the hollow 113 of the bobbin 11 at the time of magnetizing is provided on both sides of the bobbin 11. Fixed to (not shown). The work stage can be driven by a minute amount by a micrometer so that the work 30 is arranged at the center of the hollow pipe 113.
As a result, the magnetized portion (magnetized body) can be uniformly magnetized.

FIG. 6 shows a cross section in the axial direction of the bobbin, in which a magnetized portion 31 which is a part of the work 30 is inserted in the central portion of the hollow pipe 113 of the bobbin in the longitudinal direction, and a pulse current is applied from the power source to the electromagnetic coil 12. The concept that the magnetized portion (magnetized body) is magnetized by applying the magnetic field 20 to the magnetized portion 20 is illustrated.
The magnetic field generated from the electromagnetic coil 12 has an elliptical shape, but by making the inner diameter of the coil as small as possible, the spread can be suppressed and the length of the unsaturated magnetized portion can be reduced to 1 mm or less.

The second embodiment will be described with reference to FIGS. 7 to 10.
Regarding the magnetic yoke 10 of the first embodiment, as shown in the axial cross-sectional view of the bobbin of FIG. 7 and the cross-sectional view of A1-A2 of the magnetic field distribution shaper of FIG. A magnetic field distribution shaper 14 is arranged for each. In the magnetic field distribution shaper 14, the permanent magnet ring 141 is surrounded by yoke parts 142 (142a, 142b, etc.) except for the electromagnetic coil 12 (flange 111 side).

In FIG. 9, a magnetized portion 31 which is a part of the work 30 is inserted in the central portion of the hollow pipe 113 of the bobbin 11 in which the magnetic field distribution shaper 14 is arranged in the longitudinal direction, and a pulse current is transmitted from the power source to the electromagnetic coil 12. The concept is illustrated in which a magnetic field 20 is generated by applying an electric current, and a magnetized portion (magnetized body) is magnetized.
The magnetic field 20 generated from the electromagnetic coil 12 repels the magnetic field of the permanent magnet of the magnetic field distribution shaper 13, and the magnetic field flow is deflected in a rectangular shape by the magnetic field distribution shapers 13 arranged on both sides of the electromagnetic coil 12. ..
Due to the deflected magnetic field 20, the magnetized portion is in a narrow and sharp magnetized state, and its strength is large.

FIG. 10 shows a comparison between the magnetic field strength curve 201 of the first embodiment and the magnetic field strength curve 202 of the second embodiment in the length direction of the magnetized body that is a part of the wire.
By installing the magnetic field distribution shaper 14, the magnetic field strength in the length direction of the magnetized body becomes sharp and shows high strength. As a result, the length of the unsaturated magnetized portion can be reduced to 0.5 mm or less.

An embodiment of the present invention comprises a power supply unit, a magnetic yoke, and a controller, and will be described with reference to FIGS. 7 and 9.
The power supply unit applied a pulse current having a current intensity of 200 mA and a pulse time of 20 msec to the electromagnetic coil 20.

The bobbin 11 has a total length of 5.0 mm, a body diameter of 2.5 mm, an inner diameter of a hollow pipe of 1.0 mm, a brim 111 of 8.0 mm, and a thickness of 0.5 mm. An enamel wire having a coil width of 4 mm and a diameter of 30 μm is wound around the electromagnetic coil 12 for 1,000 turns.

The magnetic field distribution shaper 14 is an NdFeB-based permanent magnet ring 141 arranged on both outer sides of the brim 112 of the bobbin 11 and magnetized in the axial direction of the bobbin 11, and its size is 7.4 mm in outer diameter and 1. It consists of 6 mm.
The yoke component 142 surrounding the permanent magnet ring 141 is made of a soft magnetic material of NiFe alloy, and its shape and size are a cup shape consisting of an outer ring shape 141a and a bottom portion inscribed in the outer ring, and a bottom portion inscribed in the inner ring shape 142b. Consists of. The outer diameter of the yoke component 142, which is the outer ring, is 8.0 mm, which is the same as the diameter of the brim 112 of the bobbin 11, and the inner diameter of the yoke component 142, which is the inner ring, is 1.0 mm, which is the same as the inner diameter of the hollow pipe 113. The thickness of the yoke component 142 is 0.3 mm for both the outer ring shape 142a, the inner ring shape 142b, and the bottom.

The work 30 was made by drawing a wire rod of commercially available austenitic stainless steel SUS304 having a diameter of 1.0 mm to a diameter of 0.5 mm and a length of 200 m. The degree of wire drawing at room temperature of 25 ° C. was 75%, and as a result, an amount of martensite of 85% was obtained.
This work 30 is inserted into the hollow pipe 113 of the bobbin 11, attached to workstations (not shown) on both sides of the bobbin 11, and a pulse current is applied to the electromagnetic coil 12 to generate a magnetic field 20 in the hollow pipe 113. The magnetized site was magnetized.

When the work 30 was extracted from the hollow pipe 113 of the bobbin 11 and the magnetized portion was measured, it was saturated and magnetized over a length of 5 mm, and a magnet of 1.3 T was successfully obtained. The length of the unsaturated magnetized portion was 0.4 mm.

INDUSTRIAL APPLICABILITY The present invention can impart a magnet function to a guide wire used in a living body by enabling a part of a small-diameter wire made of hard magnetic stainless steel to be saturated and magnetized in the longitudinal direction. This can be expected to identify the tip position of the guide wire and use it for robot treatment and the like.

10: Magnetized yoke 11: Bobbin 111: Brim, 112: Body, 113: Hollow part 12: Coil 13: Temperature sensor 14: Magnetic field distribution shaper 141: Permanent magnet (NdFeB magnet), 142: York, 142a: Outer ring Part of the yoke consisting of the shape, 142b: Part of the yoke consisting of the inner ring shape, 143: Hollow pipe,
20: Magnetic field (flow of magnetic field lines)
201: Magnetic field curve without magnetic field distribution shaper, 202: Magnetic field curve with magnetic field distribution shaper 30: Work 31: Magnetized part (magnetized body)

Claims (3)

A magnetizing device including a magnetizing yoke that magnetizes a workpiece composed of a power supply unit that generates a constant current and a magnetic material, and a controller that controls the temperature of the electromagnetic coil of the magnetizing yoke.
The work has a diameter d of 0.1 to 1.5 mm, a length of 100 mm or more, and a saturated magnetized magnet portion (referred to as a saturated magnetized portion) having a length l of 1 to 8 mm.
The magnetizing yoke includes a bobbin and an electromagnetic coil that winds the bobbin, and the width L of the electromagnetic coil is 1 to 8.4 mm, and L / l with respect to the length l of the saturated magnetizing portion. Consists of 0.9-1.1
The bobbin is provided with a brim at both ends and a hollow pipe for inserting the work, and the bobbin inner diameter D is 0.3 to 2.0 mm and the D / d is 1 to 2 or less.
The coil has an enamel wire having a diameter of 10 to 50 μm having 500 to 3,000 turns and a winding density of 400 times / mm or more.
A magnetizing apparatus characterized in that the length Δl of each of the unsaturated magnetized portions on both sides of the saturated magnetized portion is 1 mm or less. In claim 1,
The power supply unit is a magnetizing device characterized in that a pulse current having a current intensity of 0.4 A or more and a pulse energization time of 0.1 msec to 20 seconds can be applied. In claim 1 or 2,
The magnetized yoke is provided with a permanent magnet ring magnetized in the direction of the bobbin axis and two magnetic field distribution shapers from a yoke component surrounding the magnetized yoke on both outer sides of the brim of the bobbin, and an early electromagnetic coil is generated. A magnetizing device characterized in that the length Δl of the unsaturated magnetized portions on both sides is 0.5 mm or less, respectively, by sealing the spread of the magnetic field distribution inside the magnetic field distribution shaper.

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