JP2005233888A - Method and equipment for manufacturing magnetic encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire a method and equipment for manufacturing magnetic encoders having high polarization efficiencies and capable of suppressing variations in magnetic flux density at each magnetic pole. <P>SOLUTION: A pair of tip parts 4c and 8a of a polarizing yoke 4 are opposed to each other in such a way as to be on both sides in radial directions of both ring-like core metal 2 and a magnetic member 3 provided for its circumferential surface. The other tip part 8a is brought into contact with the core metal 2. Then magnetic flux is made to penetrate through the magnetic member 3 while making the other tip part 8a follow a circumferential surface 3a of the magnetic member 3 in such a way that the rotating magnetic member 3 and the other tip part 8a may maintain a uniform interval with each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a manufacturing method and a manufacturing apparatus for a magnetic encoder provided in a wheel bearing or the like.

  Conventionally, as a method for manufacturing the magnetic encoder 40, for example, as described in Patent Document 1, there is a method of magnetizing the magnetic member 41 by an index magnetization method (see FIG. 6). In this method of manufacturing the magnetic encoder 40, the left and right magnetizing yokes 43 through which the magnetic flux passes are sandwiched between the magnetic member 41 and the annular member 42 in order to obtain the magnetic encoder 40 having a large magnetization strength and a small magnetization pitch. The magnetic member 41 is arranged and the magnetic member 41 is multipolarly magnetized in the circumferential direction by passing the magnetic flux A through the sandwiched portion.

At this time, the NS pole pattern is magnetized by the magnetic flux A while rotating the magnetic member 41 and the annular member 42 with a spindle (not shown). The pole width of the magnetized pattern is the width of the tip of the magnetizing yoke 43. Depends on. Therefore, when an extremely fine pitch magnetized pattern is engraved, the magnetizing yoke 43 is made of a metal such as an SS material that is easy to ultrafine and is soft magnetic. Further, the magnetization efficiency of the magnetic member 41 is improved as the distance d between the magnetic member 41 and the magnetized yoke 43 is decreased.
JP 2001-242187 A (Claim 6)

  However, the magnetic member 41 is made of a soft material having a synthetic resin as a base material. Therefore, when manufacturing the magnetic encoder 40, it is difficult to suppress the roundness and surface waviness of the magnetic member 41. It is. If there is such a undulation, the distance d between the rotating magnetic member 41 and the magnetizing yoke 43 fluctuates, and there is a problem that the magnetic flux density varies for each magnetic pole magnetized on the magnetic member 41. There is also a problem that the magnetizing efficiency is lowered when the distance d is increased.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to obtain a method and an apparatus for manufacturing a magnetic encoder having high magnetization efficiency and suppressing variation in magnetic flux density for each magnetic pole.

In order to achieve the above object, the present invention takes the following technical means.
That is, in the present invention, a pair of tip portions of the magnetizing yoke are arranged to face each other so that an annular core bar and a magnetic member provided on the peripheral surface thereof are sandwiched from the radial direction, and one of the tip portions is disposed on the core. A method of manufacturing a magnetic encoder that abuts against gold and allows magnetic flux to penetrate through the rotating magnetic member, wherein the tip is arranged so that a distance between the rotating magnetic member and the other tip is constant. The magnetic flux is penetrated while following the peripheral surface of the magnetic member.
According to the manufacturing method of the present invention described above, the distance (including zero) follows the peripheral surface of the magnetic member on which the other end of the magnetized yoke rotates. Therefore, even if the circumferential surface of the magnetic member is wavy, the magnetic member can be magnetized with the other end of the tip as close as possible to the circumferential surface. Moreover, the fluctuation | variation of the space | interval of the surrounding surface of a magnetic member and the other of the said front-end | tip part can be suppressed.

  In the method for manufacturing the magnetic encoder described above, it is preferable that a radial displacement of the circumferential surface of the magnetic member is detected in advance and the other end of the tip portion is made to follow based on the detection result. Thereby, since the front-end | tip part of a magnetizing yoke can be accurately moved based on the information acquired previously, the said front-end | tip part can be brought closer to the said magnetic member, and the effect of suppressing the fluctuation | variation of the said space | interval is also large.

  In the magnetic encoder manufacturing method described above, the other end of the tip may be brought into contact with the magnetic member, and the tip may be caused to follow by being biased in the contact direction. In this case, since the magnetic member can be magnetized while the tip of the magnetizing yoke is in contact with the peripheral surface of the magnetic member, the magnetization strength of the magnetic member is further increased.

In the present invention, the pair of tip portions of the magnetizing yoke are arranged to face each other so that the annular core bar and the magnetic member provided on the peripheral surface thereof are sandwiched from the radial direction, and one of the tip portions is disposed on the core. An apparatus for manufacturing a magnetic encoder that abuts against gold and allows magnetic flux to pass through the rotating magnetic member, wherein the distal end portion is fixed so that the interval between the rotating magnetic member and the other end portion is constant. A follow-up means for following the peripheral surface of the magnetic member is provided.
According to the above-described apparatus of the present invention, the other end of the magnetized yoke follows the peripheral surface of the rotating magnetic member so that these intervals (including zero) are constant. Therefore, even if the circumferential surface of the magnetic member is wavy, the magnetic member can be magnetized with the other end of the tip as close as possible to the circumferential surface. Moreover, the fluctuation | variation of the space | interval of the surrounding surface of a magnetic member and the other of the said front-end | tip part can be suppressed.

  As described above, according to the present invention, the tip of the magnetizing yoke can be brought as close as possible to the peripheral surface of the magnetic member, and fluctuations in the distance between the tip and the peripheral surface can be suppressed. It is possible to obtain a magnetic encoder manufacturing method and manufacturing apparatus that have efficiency and suppress variations in magnetic flux density for each magnetic pole.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an embodiment of a magnetic encoder manufacturing apparatus 1 according to the present invention, and FIG. 2 is a bottom view thereof. A magnetic encoder E (referred to as a magnetic encoder before and after magnetization, hereinafter the same) is fixed to an annular cored bar 2 having a required diameter and an outer peripheral surface of the cored bar 2 as shown in FIG. For example, the magnetic member 3 is employed in a rolling bearing device having a rotation detector for detecting a rotation speed.

  The magnetic encoder manufacturing apparatus 1 magnetizes the magnetic member 3 by an index magnetization method. In this manufacturing apparatus 1, a pair of tip portions (magnetized portions) 4c and 8a of a magnetizing yoke 4 around which an exciting coil 5 is wound are opposed to each other so as to sandwich the tip portion 8a from the radial direction of the magnetic encoder E. The magnetic member 3 is made to have multiple magnetic poles alternately in the circumferential direction by causing the magnetic member 3 to pass through the magnetic flux while causing the follower F to follow the peripheral surface of the magnetic member 3. The magnetic encoder E can be index-rotated by a spindle device (not shown), and is installed so that the outer diameter fluctuation of the outer peripheral surface 3a becomes small during rotation. In addition, a spindle device is used which has less rotational shake and uneven speed and is excellent in index accuracy.

  Although not shown, the magnetic encoder manufacturing apparatus 1 is further provided with a magnetizing power source and control means for controlling the magnetizing power source and the spindle device. Among these, the magnetizing power source applies a magnetizing current to the exciting coil 5 wound around the magnetizing yoke 4, and thereby the magnetizing yoke 4 is adjusted in accordance with the rotational speed of the spindle device and the conditions of the magnetized magnetic pole. The direction of the magnetic flux passing through is switched.

  As shown in FIG. 1, the magnetized yoke 4 is formed with left and right arm portions 4b that are divided into two portions from the main body portion 4a, and the exciting coils 5 are wound around the arm portions 4b and 4b, respectively. . A movable arm portion 8 is provided at the lower end of the right arm portion 4b. The movable arm portion 8 has substantially the same shape as the left arm portion 4b and is slidable in the left-right direction in FIG. As shown in FIG. 2, the distal end portion 4 c of the left arm portion 4 b and the distal end portion 8 a of the movable arm portion 8 have a spire shape in which the distal end side becomes gradually narrower toward the circumferential surface of the magnetic encoder E. . The tip portions 4c and 8a are formed so as to face each other, and one of the tip portions 4c is in contact with the cored bar 2, and the other tip portion 8a is arranged to face the magnetic member 3. . That is, both the tip portions 4c and 8a are arranged so as to sandwich the core metal 2 and the magnetic member 3 from the radial direction.

Next, the following means F for causing the distal end portion (the other end portion) 8a of the movable arm portion 8 to follow the peripheral surface of the magnetic member 3 will be described.
The follow-up means F detects the radial displacement of the movable arm portion 8, the rack portion 9 provided on the movable arm portion 8, the motor 11 provided with the pinion gear 10, and the outer peripheral surface 3a of the magnetic member 3. And a control device 13 for controlling the movement of the motor 11. As shown in FIG. 1, a groove 8b is formed in the movable arm 8, and a rail 4d that can be fitted into the groove 8b is formed at the lower end of the right arm 4b. Then, the movable arm portion 8 is slidable with respect to the right arm portion 4b by fitting the rail portion 4d into the groove portion 8b. The rail portion 4d is in close contact with the groove portion 8b, whereby a magnetic path is formed from the right arm portion 4b to the movable arm portion 8 without a gap.

  The rack portion 9 is fixed to the right end portion of the movable arm portion 8 with the left-right direction in FIG. The pinion gear 10 is meshed with the rack portion 9. Therefore, the rack portion 9 moves in the left-right direction via the pinion gear 10 when the motor 11 is driven. As the rack portion 9 moves, the distal end portion 8a of the movable arm portion 8 slides along the radial direction of the magnetic encoder E as shown in FIG. The motor is a stepping motor, and the controller 13 uses a motor driver that drives the stepping motor in accordance with the output of the displacement sensor.

  As shown in FIG. 2, the displacement sensor 12 is disposed slightly away from the outer peripheral surface of the magnetic encoder E (the outer peripheral surface 3a of the magnetic member) in the radial direction. Further, the displacement sensor 12 is n times as long as the magnetization pitch (distance between NS) is P than the magnetization position between the tip portions 4c and 8a on the circumference of the magnetic encoder E (n is n). (Natural number), that is, n · P is arranged at the front position in the rotation direction C. Further, the detection sensor 12 and the control device 13, and the control device 13 and the motor 11 are connected by lead wires 18, respectively. If the distance between the displacement sensor 12 and the outer peripheral surface 3a of the magnetic member 3 facing the displacement sensor 12 is ds, the displacement sensor 12 outputs a signal Vs corresponding to the distance ds. The control device 13 is preliminarily displaced from the relationship between the distance ds and the signal Vs, the relationship between the rotation amount of the motor 11 and the movement amount of the movable arm unit 8, and the rotation speed of the magnetic member 3 and the value of n · P. The number of index steps (= n) until the portion on the outer peripheral surface 3a detected by the sensor 12 reaches the magnetized position between the tip portions 4c and 8a is stored.

  In the follow-up means F configured as described above, it is necessary to perform initial setting in advance. Specifically, the position of the movable arm 8 is adjusted so that a predetermined target gap d (FIG. 4) is formed between the tip 8a of the movable arm 8 and the outer peripheral surface 3a of the magnetic member 3. do. Further, the displacement sensor 12 is fixed so that the distance ds (FIG. 2) between the magnetic member 3 and the outer peripheral surface 3a becomes a predetermined value dso, and the output signal Vso of the displacement sensor 12 corresponding to the distance dso is controlled by the control device 13. Remember me. This initial setting is preferably performed in a state in which the magnetic member 3 whose swell of the outer peripheral surface 3a is known to be within an allowable range is mounted.

  Further, the control device 13 that is magnetized operates as follows. First, the displacement sensor 12 outputs a signal Vs corresponding to the distance ds from the outer peripheral surface 3a of the magnetic member 3 facing the displacement sensor 12. Receiving this, the control device 13 calculates the interval ds and the difference Δd (= ds−dso) between this and the initial set value. Then, the motor 11 is driven so that the tip end portion 8a performs the slide operation of (−Δd) at a time point after the number of index steps. As a result, when the portion on the outer peripheral surface 3a having a displacement of Δd with respect to the initial setting value reaches the magnetized position between the tip portions 4c and 8a, the other tip 8a of the tip portion performs a slide operation of (−Δd). And displacement is offset. Accordingly, the distance d between the other end 8a of the tip and the outer peripheral surface 3a is constant. Thus, by detecting the displacement of the outer peripheral surface 3a and canceling it when magnetized, the distance d is maintained at a constant value, and the other end 8a of the tip portion is swung (radial direction) on the outer peripheral surface 3a of the magnetic member 3. (Following displacement) can be faithfully followed. Further, since the value of d can be kept constant, it is possible to increase the magnetization efficiency by making this value as small as possible.

  The core metal 2 is made of a magnetic metal. The cored bar 2 is not particularly limited, but is preferably a magnetic material. By using the cored bar 2 as a magnetic material, the tip end 4c is extended by the thickness of the cored bar 2, and there is no gap at the time of magnetization on the one end 4c side of the tip, thereby increasing the magnetization strength. Because it can. The magnetic member 3 includes a synthetic resin (eg, polyamide, polyolefin, acrylic rubber elastomer, fluororubber elastomer, silicone elastomer, ethylene copolymer, etc.) and magnetic powder (eg, barium ferrite, strontium ferrite powder, etc.) ) And kneaded uniformly.

Next, a method for manufacturing the magnetic encoder according to the present embodiment using the following means F will be described with reference to FIGS.
The magnetic encoder E is disposed between the tip 4c of the left arm 4b and the tip 8a of the movable arm 8 facing each other, and one of the tips 4c is brought into contact with the inner periphery of the core metal 2. Next, the initial setting of the follow-up means F is performed in a state where the other end 8a of the tip portion is as close as possible to the outer peripheral surface 3a of the magnetic member 3, so that the other end 8a of the tip portion can follow the outer peripheral surface 3a. Further, the magnetic encoder E is rotated (stepping) at a constant rotational speed of several tens of rpm by the spindle device. However, it is necessary to idle n steps before starting the magnetization.

Subsequently, a sine wave current, a rectangular wave current or a sawtooth wave current from the magnetizing power source is passed through the exciting coil 5, and the magnetic flux A emitted from the magnetizing yoke 4 is passed through the magnetic member 3 of the magnetic encoder E, thereby The number of poles is alternately changed in the circumferential direction. Magnetization is performed while rotating the magnetic encoder E many times. At the beginning of magnetization, the magnetizing current is gradually increased, and after reaching a constant current, the magnet is repeatedly rotated several times, and the current is decreased after completion. I will let you.
The flow of the magnetic flux will be described with reference to FIG. 4. The magnetic flux A emitted from the tip 8a of the movable arm 8 passes through the magnetic member 3 and the cored bar 2 of the magnetic encoder, and then the tip of the left arm 4b. 4c enters and returns to the magnetized yoke 4. At this time, the magnetic member 3 is alternately made into multiple magnetic poles in the circumferential direction by switching the magnetizing current on and off and switching the direction.

  According to the manufacturing method and the manufacturing apparatus 1 of the magnetic encoder, the distal end portion 8a of the movable arm 8 follows the outer peripheral surface 3a of the magnetic member 3 rotating so that these intervals are constant. Therefore, even if the outer peripheral surface 3a has a undulation, the magnetic member 3 can be magnetized with the tip 8a of the movable arm 8 as close as possible to the outer peripheral surface 3a. Moreover, the fluctuation | variation of the space | interval of the outer peripheral surface 3a and the front-end | tip part 8a of the movable arm 8 can be suppressed. Thereby, the magnetic member 3 is magnetized with high magnetization efficiency, and variation in magnetic flux density for each magnetic pole of the magnetic member 3 is suppressed. That is, it is possible to obtain a magnetic encoder E that has high magnetization efficiency and suppresses variations in magnetic flux density for each magnetic pole.

  FIG. 5 is a main part schematic diagram showing a second embodiment of the magnetic encoder manufacturing apparatus according to the present invention. The present embodiment is different from the first embodiment in that the movable arm 8 is biased toward the magnetic encoder E by the elastic member 15 in the follower F. A spring 15 that generates a preload that can follow the radial displacement of the peripheral surface of the magnetic member 3 is employed as the elastic member. A concave portion 8 c having a circular cross section is formed at the right end portion of the movable arm portion 8. Further, a contact member 16 is installed at the right end portion of the spring 15, and a contact portion 16 a is formed on the contact member 16. When the spring 15 is held in the concave portion 8c and abuts against the abutting portion 16a, the movable arm portion 8 is urged to the left and the tip 8a of the movable arm portion 8 is moved to the magnetic member 3. It is in contact.

According to the manufacturing method and the manufacturing apparatus of the magnetic encoder according to the present embodiment, the magnetic member 3 is magnetized in a state where the tip 8a of the movable arm 8 is in contact with the magnetic member 3 (the interval is zero). Therefore, it is possible to obtain a magnetic encoder having higher magnetization strength and suppressing variation in magnetic flux density for each magnetic pole.
In addition, all the said Example is illustrations, Comprising: It is not restrictive. For example, in the follow-up means F of the second embodiment, a resin member such as rubber may be employed instead of the spring.

It is a top view which shows schematic structure of the manufacturing apparatus of a magnetic encoder. It is a bottom view of FIG. It is a longitudinal cross-sectional view of a magnetic encoder. It is an enlarged view of the front-end | tip part vicinity of the movable arm part in FIG. It is a top view which shows the principal part schematic structure of the manufacturing apparatus of the magnetic encoder concerning 2nd embodiment. It is an enlarged view corresponding to FIG. 4 in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic encoder manufacturing apparatus 3 Magnetic member 3a Peripheral surface of magnetic member 4 Magnetization yoke 8 Movable arm part 8a Tip part 9 Rack part 10 Pinion gear 11 Motor 12 Displacement sensor 13 Control apparatus 15 Spring F Follow-up means

Claims (4)

A pair of tip portions of the magnetizing yoke are arranged to face each other so as to sandwich the annular core metal and the magnetic member provided on the peripheral surface from the radial direction, and one of the tip portions is brought into contact with the core metal, A method of manufacturing a magnetic encoder for passing magnetic flux through the rotating magnetic member,
A method of manufacturing a magnetic encoder, comprising: passing a magnetic flux while causing the tip portion to follow the peripheral surface of the magnetic member so that a distance between the rotating magnetic member and the other tip portion is constant. The method of manufacturing a magnetic encoder according to claim 1, wherein a radial displacement of the circumferential surface of the magnetic member is detected in advance, and the tip portion is caused to follow based on the detection result.   The method of manufacturing a magnetic encoder according to claim 1, wherein the other end of the tip is brought into contact with the magnetic member and biased in a contact direction to cause the tip to follow. A pair of tip portions of the magnetizing yoke are arranged to face each other so as to sandwich the annular core metal and the magnetic member provided on the peripheral surface from the radial direction, and one of the tip portions is brought into contact with the core metal, An apparatus for manufacturing a magnetic encoder for passing magnetic flux through the rotating magnetic member,
An apparatus for manufacturing a magnetic encoder, comprising: follow-up means for causing the tip portion to follow the peripheral surface of the magnetic member so that a distance between the rotating magnetic member and the other tip portion is constant.

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