JP2012119472A - Flexible magnet, manufacturing method of the flexible magnet, magnetic encoder, and actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible magnet which has strong magnetic force and excellent flexibility.SOLUTION: A flexible magnet M has a first sheet 1 formed by including rare earth magnetic powder in a resin and magnetizing a surface to an N pole and a S pole and a second sheet 2 formed by including ferrite magnetic powder in a resin and secured to a rear surface of the first sheet 1.

Description

  The present invention relates to a flexible magnet having N and S poles magnetized on its surface, a method of manufacturing a flexible magnet, a magnetic encoder, and an actuator.

A linear magnetic scale in which N poles and S poles are alternately magnetized on the surface of a strip-shaped magnetic member is known.
This linear magnetic scale is used as a part of a linear magnetic encoder. That is, a relative position between the magnetic scale and the magnetic sensor is detected by disposing a magnetic sensor such as an MR sensor so as to be opposed to the linear magnetic scale. For example, it is used as a linear magnetic encoder that detects the position of a movable part of a linear motor.

  A linear magnetic encoder used for a linear motor or the like is required to be hardly affected by an external magnetic field. That is, it is required that the magnetic output from the linear magnetic scale is large and stable. For this reason, a magnet having a strong magnetic force such as a neodymium magnet is used.

  In addition, the linear magnetic scale may be required to be bendable in order to be used for measuring a curved portion. For this reason, a flexible magnet called a bond magnet is used. Bond magnets are magnets that are crushed and kneaded into rubber or plastic, and are also called rubber magnets, polyvinyl chloride magnets, plastic magnets, or the like.

  However, a bond magnet obtained by kneading a neodymium magnet or the like into rubber or the like has a property of being brittle. For this reason, what adhered the metal plate, such as a stainless steel plate, to the back side of the sheet-like bond magnet containing a neodymium magnet etc. is used (refer patent document 1).

Japanese Patent Laid-Open No. 11-148842

  In the case where a reinforcing member such as a metal plate is attached to the back side of a sheet-like bond magnet including a neodymium magnet or the like, the original flexibility and flexibility of the bond magnet are impaired. In addition, problems such as weight, rust, temperature deformation, and cost increase occur.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a flexible magnet having a strong magnetic force and a high flexibility, a method for manufacturing the flexible magnet, a magnetic encoder, and an actuator. And

The present invention employs the following means in order to solve the above problems.
The flexible magnet according to the present invention is formed by containing a rare earth magnetic powder in a resin, and by forming a first sheet having N and S poles magnetized on the surface, and a ferrite magnetic powder in the resin. And a second sheet fixed to the back surface of the first sheet.

  The method for producing a flexible magnet according to the present invention includes a step of forming a first sheet by containing rare earth magnetic powder in a resin, a step of forming a second sheet by adding ferrite magnetic powder to the resin, The method includes: a step of superimposing and fixing the first sheet and the second sheet; and a step of magnetizing an N pole and an S pole on the surface of the first sheet.

  A magnetic encoder according to the present invention is a magnetic encoder comprising a magnetic scale whose surface is magnetized with an N pole and an S pole, and a magnetic sensor arranged to face the magnetic scale. A flexible magnet or a flexible magnet manufactured by the method for manufacturing the flexible magnet is used.

  An actuator according to the present invention includes a magnet portion having N and S poles magnetized on a surface thereof, and a coil portion in which a plurality of coils are arranged to face the magnet portion, and the magnetic field of the magnet portion and the In the actuator that moves relative to the magnet part and the coil part by the current flowing through the coil, the flexible magnet manufactured by the flexible magnet or the flexible magnet manufacturing method is used as the magnet part. It is characterized by.

According to the flexible magnet and the method of manufacturing a flexible magnet according to the present invention, the second sheet functions as a reinforcing member for the first sheet. Therefore, even when the flexible magnet is bent or twisted. The first sheet does not crack or tear.
Moreover, since the flexible magnet has the first sheet having a high strength magnetic force, it can be suitably used for a magnetic scale or the like. Moreover, since it has high softness | flexibility and flexibility, a flexible magnet can be attached in close contact with the curved part etc. according to the shape.

  According to the magnetic encoder and the actuator according to the present invention, the first sheet generates a strong magnetic force. Therefore, the magnetic encoder can improve and stabilize the detection accuracy, and the actuator can obtain a high driving force.

It is a perspective view showing a schematic structure of an actuator (linear motor) concerning an embodiment of the present invention. It is an expansion perspective view (partial sectional view) showing a base and a table. It is sectional drawing which shows schematic structure of an actuator. It is a perspective view which shows a coil part. It is sectional drawing which shows the structure of a linear guide. It is the perspective view and sectional drawing which show the structure of the flexible magnet which concerns on embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing a schematic configuration of an actuator A (linear motor 5) according to an embodiment of the present invention.
FIG. 2 is an enlarged perspective view (partially sectional view) showing the base 10 and the table 20.
FIG. 3 is a cross-sectional view showing a schematic configuration of the linear motor 5.

The actuator A includes a linear motor 5, a motor driver 80 (control device) that controls the linear motor 5, and a user terminal 90 (information processing device) connected to the motor driver 80.
The linear motor 5 includes a base 10 that is elongated in one axial direction (X direction) and a table 20 that is slidable with respect to the base 10.
A pair of linear guides 50 is provided between the base 10 and the table 20 so that the table 20 can slide smoothly with respect to the base 10.

The position / velocity / acceleration of the table 20 with respect to the base 10 is detected by the linear magnetic encoder 60 (see FIG. 3). The linear magnetic encoder 60 has a resolution of about 1 μm, for example.
The linear magnetic encoder 60 includes a magnetic scale 61 attached to the base 10 and a magnetic sensor 62 attached to the table 20.

The magnetic scale 61 is made of an elongated rectangular magnetic body, and its upper surface is magnetized so that N poles and S poles alternately have a constant pitch (for example, 2 mm).
The magnetic scale 61 is disposed in close contact with the outer surface of the side wall 12 of the base 10 along the longitudinal direction (X direction) of the base 10.

A flexible magnet M is used as the magnetic scale 61 (see FIG. 6).
The flexible magnet M is a bonded magnet formed in a two-layer structure of a first sheet 1 having a strong magnetic force and a second sheet 2 having a weak magnetic force welded to the back surface 1 b of the first sheet 1. On the surface (upper surface) of the first sheet 1, N poles and S poles are alternately magnetized along the longitudinal direction at a constant pitch. The detailed configuration of the flexible magnet M will be described later.
The flexible magnet M is fixed along the longitudinal direction (X direction) of the base 10. Specifically, the second sheet 2 on the back surface side is closely fixed by placing a double-sided tape or an adhesive between the bottom wall portions 11 of the base 10. Thereby, the first sheet 1 on the front side functions as a magnetic scale.

The magnetic sensor 62 detects the magnetism of the magnetic scale 61 with an MR element, and outputs a sine wave signal by relatively moving along the magnetic scale 61.
The signal detected by the magnetic sensor 62 is sent to the motor driver 80 via a signal processing unit (not shown). And the motor driver 80 controls the electric current supplied to the coil part 40 so that the table 20 moves to a command position based on the position command from the user terminal 90. In this way, the linear motor 5 is controlled.

  As a control method of the linear motor 5, feedback control or the like is performed. That is, the position information, speed information, and acceleration information of the table 20 detected by the table 20 are sent to the motor driver 80, and the difference from the target value (command value) is calculated. The three-phase alternating current with respect to the three coils 41 of the coil part 40 is controlled so that it may approach.

The base 10 is formed of an elongated rectangular bottom wall portion 11 and a pair of side wall portions 12 provided perpendicular to both ends in the width direction (Y direction) of the bottom wall portion 11. The base 10 is made of, for example, a magnetic material such as steel or a nonmagnetic material such as aluminum.
A magnet portion 30 in which a plurality of magnets are arranged is attached to the upper surface of the bottom wall portion 11 of the base 10.
Further, the track rails 51 of the linear guide 50 are arranged along the uniaxial direction on the upper surfaces of the side wall portions 12 of the base 10. The two track rails 51 are arranged in parallel, and two moving blocks 52 are attached to each.

The table 20 is made of a nonmagnetic material such as aluminum and is formed in a rectangular plate shape.
The moving blocks 52 of the linear guide 50 are attached to the four corners of the lower surface 20b of the table 20. The moving block 52 is attached to the two track rails 51 described above. In other words, the table 20 is supported on the base 10 by the pair of linear guides 50 so as to be linearly movable.

In addition, a coil unit 40 including three coils 41 and the like is suspended between the four moving blocks 52 on the lower surface of the table 20. The three coils 41 function as a three-phase coil (armature).
A gap g is set between the magnet portion 30 attached to the base 10 and the coil portion 40 attached to the table 20. The gap g is kept constant even when the table 20 moves linearly with respect to the base 10 by the pair of linear guides 50.

  The magnet unit 30 generates a magnetic field toward the coil unit 40. Specifically, the magnet unit 30 is a magnet formed in an elongated rectangular plate shape, and the surface (upper surface) of the base 10 in the longitudinal direction (X direction) of the base 10 is alternately arranged at a constant pitch. It is magnetized along.

A flexible magnet M is used as the magnet unit 30 (see FIG. 6).
The flexible magnet M used for the magnet unit 30 has the same configuration as the flexible magnet M used for the magnetic scale 61. However, the shape dimensions, magnetic force, magnetization pitch, and the like are changed according to the required specifications of the magnet unit 30.
The flexible magnet M is fixed along the longitudinal direction (X direction) of the base 10. Specifically, a double-sided tape or an adhesive is placed between the second sheet 2 on the back surface side and the bottom wall portion 11 of the base 10 to fix it tightly. Thereby, a magnetic field is generated from the first sheet 1 on the front side toward the coil unit 40.

FIG. 4 is a perspective view showing the coil unit 40.
A coil portion 40 as an armature composed of three coils 41 functioning as a three-phase coil and a core 42 is attached to the central portion of the lower surface of the table 20. The material of the core 42 is a magnetic material such as silicon steel. The core 42 has three comb teeth 42a, 42b, and 42c that strengthen the magnetic field generated in the three-phase coil (coil 41).
The three coils 41 are respectively wound around the three comb teeth 42a, 42b, and 42c of the core 42 to form a U-phase coil 41a, a V-phase coil 41b, and a W-phase coil 41c. The three coils 41 are arranged along the moving direction of the table 20.

The three coils 41 are supplied with three-phase alternating currents having different phases by 120 degrees. As a result, a traveling magnetic field is generated from the coil unit 40. Thereby, a thrust is generated in the coil unit 40 (table 20) by the action of the magnetic field generated in the magnet unit 30.
The current flowing through the three coils 41 of the coil unit 40 is controlled by the motor driver 80.

FIG. 5 shows a perspective view of the linear guide 50.
The linear guide 50 has a track rail 51 attached to the upper surface of the side wall portion 12 of the base 10.
A plurality of mounting holes 51b are formed in the track rail 51 at a predetermined pitch in the longitudinal direction. The track rail 51 is fixed to the side wall portion 12 by passing a bolt through the mounting hole 51 b and screwing the bolt into the screw hole of the side wall portion 12 of the base 10.
A plurality of ball rolling grooves 51a in which the balls 55 roll along the longitudinal direction are formed on the track rail 51. The cross-sectional shape of the ball rolling groove 51a is a circular arc groove shape made of a single arc slightly larger than the radius of the ball 55, or a Gothic arch groove shape made of two arcs.
The ball rolling groove 51 a is formed not only on the side surface of the track rail 51 but also on the upper surface of the track rail 51. By forming the ball rolling groove 51 a on the upper surface of the track rail 51, the vertical rigidity of the linear guide 50 can be increased.

The moving block 52 is formed in a bowl shape straddling the track rail 51. In the moving block 52, a load ball rolling groove 52a facing the ball rolling groove 51a of the track rail 51 is formed, and a ball circulation path including the load ball rolling groove 52a is formed.
An end plate 53 is attached to each end face of the moving block 52 in the uniaxial direction. The ball circulation path includes a load ball rolling groove 52a, a ball return path 52b extending in parallel with the load ball rolling groove 52a, an end plate 53 and an end of the load ball rolling groove 52a and the ball return path 52b. And a U-shaped direction change path 52c connecting the end portions of the two, and the whole is formed in a circuit shape.
A plurality of balls 55 are arranged and accommodated in the ball circulation path.
A mounting screw 52d for mounting the table 20 is processed on the moving block 52. The moving block 52 is screwed to the lower surface 20 b of the table 20.

  When the moving block 52 is moved relative to the track rail 51, the ball 55 interposed between the ball rolling groove 51a of the track rail 51 and the loaded ball rolling groove 52a of the moving block 52 rolls. . The ball 55 rolled to one end of the load ball rolling groove 52a is guided to the direction changing path 52c, passes through the ball return path 52b and the opposite direction changing path 52c, and then to the other end of the load ball rolling groove 52a. Returned. By interposing the ball 55 between the track rail 51 and the moving block 52, the resistance when the moving block 52 moves with respect to the track rail 51 can be reduced.

Next, a detailed configuration of the flexible magnet M will be described.
FIG. 6 is a perspective view and a sectional view showing the configuration of the flexible magnet M according to the embodiment of the present invention.
The flexible magnet M is a sheet-like bond magnet formed in an elongated rectangular plate shape. The flexible magnet M includes a first sheet 1 having a strong magnetic force and a second sheet 2 having a weak magnetic force welded to the back surface 1b of the first sheet 1. That is, the flexible magnet M is a bonded magnet formed in a two-layer structure of the first sheet 1 and the second sheet 2.

The first sheet 1 is formed with, for example, a short side direction of 10 mm, a long side direction of 1 m, and a thickness of 1 mm. The surface 1a of the first sheet 1 is alternately magnetized with N and S poles at a pitch of 2 mm in the longitudinal direction, for example.
The first sheet 1 is formed by kneading rare earth magnetic powder into a binder resin such as vulcanized rubber or elastomer to form an elongated rectangular plate. As the rare earth magnetic powder, a powder of neodymium, samarium-cobalt, samarium-iron nitride or the like is used. Therefore, the first sheet 1 generates a high strength magnetic force.

The second sheet 2 is formed in the same shape as the first sheet 1. That is, the second sheet 2 is formed with, for example, a short side direction of 10 mm and a long side direction of 1 m. The second sheet 2 is formed thicker than the first sheet 1. For example, the thickness of the second sheet 2 is 3 mm.
The second sheet 2 is formed in the shape of an elongated rectangular plate by kneading ferrite magnetic powder in a binder resin such as vulcanized rubber or elastomer.
As the ferrite-based magnetic powder, manganese zinc ferrite, nickel zinc ferrite, copper zinc ferrite and the like are used. Therefore, the second sheet 2 generates a weak magnetic force as compared with the first sheet 1.

The flexible magnet M is manufactured through the following steps.
First, the first sheet 1 and the second sheet 2 are formed separately. That is, the magnetic powder is kneaded into a binder resin such as vulcanized rubber to form an elongated rectangular plate. At this time, the binder resin used for the first sheet 1 and the second sheet 2 is preferably the same. This is because the hardness, flexibility, and flexibility of the first sheet 1 and the second sheet 2 are matched.
The content of magnetic powder (neodymium, ferrite, etc.) with respect to the binder resin can be arbitrarily set. For example, a sufficient magnetic force can be obtained by containing 80 percent or more of magnetic powder.

  Next, after the first sheet 1 and the second sheet 2 are overlapped, the first sheet 1 and the second sheet 2 are welded by heating. For example, the first sheet 1 and the second sheet 2 are welded using a press molding machine. When the thickness of the first sheet 1 is 1 mm and the thickness of the second sheet 2 is 3 mm, a flexible magnet M having a thickness of 4 mm is obtained.

Finally, N poles and S poles are alternately magnetized on the surface 1 a of the first sheet 1. The arrangement pitch of the N pole and the S pole can be arbitrarily set.
As described above, when the flexible magnet M is used as a magnetic scale, it is magnetized at a pitch of 2 mm, for example, and when it is used as a magnet part of a linear motor, it is magnetized at a pitch of several mm to several tens of mm, for example.
In addition, when magnetizing the surface 1a of the 1st sheet | seat 1, the 1st sheet | seat 2 may be magnetized simultaneously.

The flexible magnet M includes a first sheet 1 having a high strength magnetic force. Therefore, it can be suitably used for the magnet unit 30 and the magnetic scale 61.
On the other hand, the first sheet 1 contains a magnetic powder such as neodymium and is brittle, but the second sheet 2 is overlapped and welded to the first sheet 1, so that the flexible magnet Even if M is bent or twisted, the first sheet 1 does not break or tear. That is, the second sheet 2 functions as a reinforcing member for the first sheet 1.

Further, the second sheet 2 also functions as a back yoke for the first sheet 1. That is, it functions as a yoke that concentrates the magnetic lines of force from the first sheet 1. Therefore, the first sheet 1 can generate a strong and stable magnetic force from the surface 1a.
In particular, since the second sheet 2 that is a bonded magnet is used as the reinforcing member of the first sheet 1, the flexibility and flexibility of the flexible magnet M are the original ones of the bonded magnet. That is, it has higher flexibility and flexibility than the conventional example using a metal plate as the reinforcing member. Therefore, the flexible magnet M can be attached in close contact with a curved portion or the like following its shape.

Such a flexible magnet M can be suitably used for the magnet unit 30 of the linear motor 5, the magnetic scale 61 of the linear magnetic encoder 60, and the like.
In particular, since the first sheet 1 generates a strong magnetic force, the linear motor 5 can obtain a high driving force, and the linear magnetic encoder 60 (magnetic scale 61) can improve detection accuracy and can be stabilized.

  Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

Although the case where the N pole and the S pole are alternately magnetized on the surface of the first sheet 1 along one direction has been described, the present invention is not limited thereto. That is, an arbitrary magnetic pattern may be formed on the surface of the first sheet 1.
Further, for example, the surface of the first sheet 1 may be alternately magnetized with N and S poles along an arbitrary curve.
In addition, for example, the surface of the first sheet 1 may be alternately magnetized with N and S poles along two directions. For example, it can be used as a magnetic scale of a planar motor or a magnetic encoder for detecting a position in two directions.

  Further, the N pole and S pole magnetized on the surface of the first sheet 1 are not limited to a constant pitch, and may be magnetized at an arbitrary interval.

  Although the case where the flexible magnet M is used for the linear magnet portion 30 and the magnetic scale 61 has been described, the flexible magnet M may be curved or bent.

  Further, the present invention is not limited to the case where a plurality of balls 55 are used as the rolling elements of the linear guide 50, and rolling elements such as rollers may be used. Further, instead of the linear guide 50, a sliding guide mechanism may be used.

Although the case where the thickness of the 2nd sheet 2 was made thicker than the 1st sheet 1 was demonstrated, you may make both thickness the same.
However, it is preferable to make the second sheet 2 thicker than the first sheet 1. This is because if the thickness of the second sheet 2 is too thin, the magnetic flux (lines of magnetic force) emitted from the first sheet 1 passes through the second sheet 2 and becomes a leakage magnetic flux to the outside. That is, since the second sheet 2 (ferrite) has a lower saturation magnetic flux density than the first sheet 1 (neodymium etc.), in order not to leak the magnetic flux from the first sheet 1 outside, This is because it is necessary to increase the magnetic flux that can be made thicker than the first sheet 1 and pass through the inside of the second sheet 2.

  Although the case where a double-sided tape or an adhesive is used when fixing the flexible magnet M has been described, the present invention is not limited thereto. When fixing the flexible magnet M to a magnetic material (such as steel), the magnetism of the flexible magnet M (second sheet 2) itself is used without using a fastening member such as a bolt or an adhesive. Then, the magnetic material may be tightly fixed. In this case, the attachment position of the flexible magnet M and the replacement of the flexible magnet M can be easily performed, and the maintenance is excellent.

  M ... Flexible magnet, 1 ... First sheet, 1b ... Back surface, 2 ... Second sheet, A ... Actuator, 5 ... Linear motor, 30 ... Magnet part, 60 ... Linear magnetic encoder, 61 ... Magnetic scale, 62 ... Magnetic sensor

Claims (5)

A first sheet formed by adding rare earth magnetic powder to a resin and magnetizing a north pole and a south pole on the surface;
A second sheet that is formed by adding a ferrite-based magnetic powder to the resin and is fixed to the back surface of the first sheet;
A flexible magnet characterized by comprising:   The flexible magnet according to claim 1, wherein the rare earth magnetic powder is a powder of neodymium, samarium-cobalt, or samarium-iron nitride. Forming a first sheet by adding rare earth magnetic powder to the resin;
Including a ferrite magnetic powder in the resin to form the second sheet;
A step of stacking and fixing the first sheet and the second sheet;
Magnetizing N and S poles on the surface of the first sheet;
The manufacturing method of the flexible magnet characterized by having. A magnetic scale with N and S poles magnetized on the surface;
A magnetic sensor disposed opposite to the magnetic scale;
In a magnetic encoder comprising:
A magnetic encoder using the flexible magnet according to claim 1 or 2 or the flexible magnet manufactured by the method for manufacturing a flexible magnet according to claim 3 as the magnetic scale. A magnet portion magnetized with N and S poles on the surface;
A coil portion in which a plurality of coils are arranged to face the magnet portion;
With
In the actuator that relatively moves the magnet part and the coil part by the magnetic field of the magnet part and the current flowing in the coil,
The actuator using the flexible magnet manufactured by the manufacturing method of the flexible magnet of Claim 1 or 2, or the flexible magnet of Claim 3 as said magnet part.

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