JP2006067652A - Cantilevered bearing mechanism and manufacturing method of same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce cost by using an inexpensive mold pressing process, and accurately and vertically fix a bearing holder to an attachment plate. <P>SOLUTION: The bearing holder internally has a thrust block and an oil retaining bearing, rotatably supports an end of a rotor shaft of an outer rotor motor, and is fixed to the attachment plate. The bearing holder is formed from a high-permeability steel plate by a drawing process, and is integrally formed with a flange, a cylinder vertically raised in the center of the flange and internally holding the oil retaining bearing, and a ceiling having an opening to which the shaft is inserted in the center. Penetration holes are circumferentially provided on one of the attachment plate and the bearing holder at regular intervals. A plurality of protrusions are provided on the other, formed by a burring process or a boss process, and fixed by caulking their tips after insertion into the penetration holes. The bearing holder is attached to the attachment plate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cantilever bearing mechanism of an outer rotor type brushless motor having a cantilever bearing configuration and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, an outer rotor type brushless motor having a cantilever bearing configuration has been used as a motor used in a disk rotation driving device such as an optical disk or a magneto-optical disk mounted on a rotor. Such a motor has a structure in which a bearing holder is fixed in a bearing holder insertion hole formed in a mounting plate and a rotor shaft is supported by a bearing portion in the bearing holder.

  In recent years, motors used in disk rotation drive devices and the like are required not only for further miniaturization and higher rotation speed, but also for suppressing disk surface runout with high accuracy during recording and playback. Has been. For this purpose, it is necessary to mount and fix the bearing device vertically with high accuracy on the motor mounting surface and to support the rotor shaft in a cantilevered manner.

  FIG. 10 is a diagram illustrating a first conventional technique for fixing a bearing device vertically with high accuracy (see Patent Document 1). The bearing holder is formed by cutting a metal such as brass (brass), and a bearing supporting the rotor shaft is press-fitted and fixed therein. The bearing holder is fixed by caulking into a bearing holder insertion hole provided in the mounting plate. By manufacturing by cutting, it becomes possible to process the bearing holder perpendicular to the flange portion of the bearing holder with high accuracy. However, brass-cut bearing holders are expensive.

  FIG. 11 is a diagram illustrating a second prior art for fixing the bearing device vertically with high accuracy (see Patent Document 2). A burring process is applied to the central part of a bracket made of a steel plate, thereby providing a bearing holder for holding the bearing. The burring process is a process of making a cylindrical portion by making a hole in a plate material (this hole is called a pilot hole), pushing a large punch into the pilot hole and extending the edge of the pilot hole. A bearing that rotatably supports the shaft is press-fitted and fixed inside a cylindrical portion (bearing holder) formed by such burring. The illustrated mechanism is composed of inexpensive parts using metal pressing, and the structure is simple and the assembly process can be simplified.

  However, in the burring process, since only the volume of the rising portion of the steel sheet can be extended, there is a limit to increasing the height of the formed cylindrical portion (bearing holder), and the entire bearing length cannot be wrapped. For this reason, a gap is formed with respect to the oil escape of the bearing, and the oil easily flows out. Further, since the cylindrical portion is formed as high as possible on the mounting plate, there is a problem that the mold structure is complicated (many stages are required) and the mold cost is increased.

  FIG. 12 is a diagram illustrating a third conventional technique for fixing a bearing device vertically with high accuracy (see Patent Document 3). Similar to the above example, the rotor shaft is rotatably supported by a bearing. The bearing holder that holds the bearing needs to be mounted perpendicular to the mounting plate. For this reason, in a state where the bearing holder is loosely fitted in the mounting portion (insertion hole) formed on the mounting plate, the assembly jig (not shown) is used to fix the bearing holder vertically with high accuracy. Thereafter, a UV curable adhesive is filled into the fitting gap between the bearing holder and the mounting portion and cured. Thus, the bearing holder and the bearing are fixed in a state where the shaft is adjusted with high accuracy with respect to the mounting plate.

However, since it is cured with a UV curable adhesive while being fixed with a jig, it requires a highly accurate jig and an expensive UV irradiation machine, requires a lot of production steps, and the adhesive used is also expensive. is there.
JP-A-10-108404 JP-A-8-289523 Japanese Unexamined Patent Publication No. 7-322554

  The present invention achieves high accuracy with respect to the mounting plate of the bearing holder while reducing the cost by using an inexpensive die press process without cutting an expensive metal material or using an expensive adhesive and equipment. It is intended to be fixed vertically.

  The cantilever bearing mechanism of the present invention has a thrust receiver and an oil-impregnated bearing inside, and rotatably supports the end portion of the rotor shaft of the outer rotor type motor, and is fixed to the mounting plate. The bearing holder is drawn by drawing from a steel plate of high permeability material, and the shaft is inserted vertically into the flange part, the cylindrical part that holds the oil-impregnated bearing inside, and the shaft passes through the center. And the ceiling part where the opening is opened is formed integrally and continuously. Either one of the mounting plate and the bearing holder is provided with through-holes at equal intervals on the circumference, and a plurality of protrusions formed by burring or boss processing provided on the other side are inserted into the through-holes and then inserted. Secure the tip of the protrusion with caulking and attach the bearing holder to the mounting plate.

  In addition, the ceiling portion has an outer surface facing inward at a right angle from the cylindrical portion facing the outer surface of the attracting magnet to function as a magnetic path of the attracting magnet, while supporting the retaining washer on the inner surface of the ceiling portion. .

  Further, the mounting plate is provided with a hollow portion having an inner diameter sufficient for a part of the oil-impregnated bearing to enter, and the bottom portion of the shaft is supported by a thrust receiver provided at the center of the bottom portion of the hollow portion.

  Furthermore, the method for manufacturing a cantilever bearing mechanism according to the present invention includes a mounting plate for a cantilever bearing mechanism having a thrust receiver and an oil-impregnated bearing therein and rotatably supporting an end portion of a rotor shaft of an outer rotor type motor. Position and fix vertically. By drawing from a high-permeability steel plate, a flange part, a cylindrical part that is raised vertically from the center of the flange part, and holding an oil-impregnated bearing inside, and an opening through which the shaft is inserted are opened in the center. A bearing holder composed of a ceiling portion formed continuously in one piece, and provided with through holes at equal intervals on the circumference of either the mounting plate or the bearing holder, and on the other of the mounting plate and the bearing holder, After forming a plurality of protrusions by burring or boss processing, correcting the perpendicularity of the bearing holder with respect to the mounting plate and inserting the protrusion, the tip side of the protrusion is fixed by caulking, and the bearing holder is attached to the mounting plate Attach to.

  In addition, the correction of the perpendicularity of the bearing holder is performed by cutting the back surface of the flange portion before attaching to the mounting plate, or by adjusting the relative angular position of the bearing holder with respect to the mounting plate, The perpendicularity is corrected by inserting a protrusion into the hole.

  According to the present invention, it is possible to reduce the material cost, jig and equipment cost by joining without using an expensive brass cut product and without using an adhesive, thereby reducing the cost of the motor. Adjusting the bearing holder tilt to the optimum place that can offset the tilt of the mounting plate against the tilt of the mounting plate while downing, or applying a squareness correction process such as cutting the mounting surface of the bearing holder mounting plate This makes it possible to produce products that are not affected by the accuracy of individual parts.

  Further, according to the present invention, not only an inexpensive die press product can be adopted, but it can also function as a back yoke or an opposing surface of the attracting magnet.

  In addition, according to the present invention, it is not necessary to add a separate piece such as a member that supports the shaft bottom, while the bearing holder is integrally provided with a ceiling portion, and the structure is formed into a bag-closing shape. The retaining washer can be sandwiched between the bearing holder and the bearing.

  Hereinafter, the present invention will be described based on examples. FIG. 1 is a diagram showing a small motor embodying the present invention, and is a front view showing a right half in section. The illustrated small motor belongs to an outer rotor type brushless spindle motor having a cantilever bearing configuration. In this small motor, a laminated core in which a winding is wound around the outer periphery of a bearing holder attached to a mounting plate is disposed on the stator side. An oil-impregnated bearing for the shaft is provided in the bearing holder, and a thrust receiver that supports a tip end portion of the shaft that is inserted through the opening of the bearing holder ceiling portion is accommodated in the center bottom portion. Here, the oil-impregnated bearing may be a middle escape bearing or two bearings that rotatably support the shaft. The structure and the mounting method of the bearing holder constitute the feature of the present invention, and details thereof will be described later.

  The rotor side is composed of a rotor case fixed to the shaft at the center and a drive magnet attached to the rotor case. This drive magnet has a cylindrical shape so as to face the laminated core on the stator side from outside in the radial direction through a gap. The illustrated brushless motor can also be provided with an electronic rectifier circuit (not shown). The electronic rectifier circuit detects the rotational angle position of the rotor using a Hall element (not shown) and controls the current flowing through each of the plurality of windings based on the detection signal. Since it is well known and is not directly related to the present invention, further explanation is omitted.

  In the illustrated small motor, a hollow cylindrical attracting magnet is attached to the rotor case by bonding or the like so as to be concentric with the shaft, but it can have a well-known configuration. The bearing holder of this invention is comprised so that the ceiling part outer surface may face this attracting magnet. As a result, the attracting magnet attached to the inner surface of the rotor case attracts the fixed bearing holder ceiling, so that the rotor is attracted to the stator side. The bearing holder ceiling has a function of locking the retaining washer in the axial direction. The retaining washer is made of an elastic plate member such as a polyslider formed in a ring shape. By locking this retaining washer that has entered into the groove of the small diameter portion formed in the shaft at the bearing holder ceiling, it is possible to prevent the shaft itself from coming out. However, since the retaining washer has elasticity, the shaft can be inserted in the axial direction or pulled out if a strong force of a predetermined value or more is applied.

  Furthermore, the illustrated motor shows an example applied to a disk rotation drive device, and a turntable on which an optical disk or the like can be placed is fixed to one end of a shaft.

  FIG. 2 is a perspective view showing only the mounting plate. A plurality of protrusions obtained by burring are provided at equal intervals on the same circumference centering on the shaft axis at the bearing holder mounting location on the mounting plate. Since the illustrated protrusion is formed by burring, it is formed into a cylindrical shape with a hole in the center and is configured integrally with the mounting plate. The number of the protrusions is preferably 3 to 6, and three in the illustrated example. Further, the mounting plate is provided with a recessed portion that has an inner diameter slightly larger than the outer diameter of the bearing and into which a part of the lower portion of the bearing can be inserted. The indented portion is a portion that supports the bottom portion of the shaft via the thrust receiver. The function of the indented portion can be sufficiently achieved by a flat mounting plate, and is not always necessary. However, the provision of the indented portion facilitates the positioning of the motor in the disk rotation driving device. It is also possible to keep the height from the motor mounting plate low. Furthermore, a recess corresponding to the outer diameter and thickness of the thrust receiver can be provided at the center bottom of the recess. As a result, the diameter of the expensive thrust receiver (for example, polyetheretherketone) is reduced, and the positioning of the thrust receiver having the smaller diameter is facilitated. In any case, as described in the prior art, when the insertion hole for mounting the bearing holder is opened in the mounting plate, a configuration for supporting the shaft end portion is separately required, whereas the configuration shown in the figure. The shaft end can be supported by the mounting plate. Since the bearing holder of the present invention does not need to be provided with a portion for supporting the shaft end, it can be integrally formed from a steel plate by drawing as described later.

  FIG. 3 is a perspective view showing only the bearing holder taken out. In the bearing holder, a flange portion, a cylindrical portion, and a ceiling portion are continuously formed integrally by drawing from a steel plate. As described above, since the bearing holder needs to function as a yoke of the attracting magnet as described above, a material having a high magnetic permeability, such as iron, cobalt, nickel, etc., preferably a galvanized steel plate Consists of In this way, the bearing holder can be produced at a low cost by drawing (pressing) instead of cutting, and by making it a high permeability material, it serves as a magnetic path for the attracting magnet. It becomes possible.

  The cylindrical portion of the bearing holder is a portion that rises vertically from the center of the flange portion and holds the bearing inside. Further, a ceiling portion is formed from the cylindrical portion toward the inward direction at a right angle. The ceiling portion has an opening through which the shaft is inserted, and the outer surface of the ceiling portion is opposed to be parallel to the outer surface of the attracting magnet so as to function as a back yoke or an opposing surface of the attracting magnet. Moreover, the ceiling part inner surface supports the retaining washer as described above. However, the retaining washer can be positioned below the bearing. The flange portion of the bearing holder is provided with a plurality of through holes used for fixing to the mounting plate. The through holes are provided at equal intervals on the same circumference corresponding to the protrusions of the mounting plate.

  After the three protrusions provided on the mounting plate are inserted into the three through holes provided in the flange portion of the bearing holder illustrated in FIG. 3, crimping is performed from the front end side of the protrusion using a caulking jig. That is, it is fixed by crushing the tip end side of the protrusion. As described above, this bearing holder is formed by drawing from a galvanized steel plate, for example, and therefore cannot be machined as accurately as it is cut. For this reason, the perpendicularity of the flange portion and the cylindrical portion of the bearing holder is not necessarily highly accurate just by drawing, but the relative positions of the three through holes with respect to the three protrusions of the mounting plate It is possible to mount the bearing holder cylindrical portion at a position where it is fixed most vertically with respect to the mounting plate while shifting by 120 (= 360/3) degrees.

  FIG. 4 is a view showing another example of the bearing holder, and is a top view seen from the ceiling side. The number of through holes provided in the bearing holder flange can be an integral multiple of the number of protrusions on the mounting plate. FIG. 4 shows an example in which nine through holes, three times as many, are provided for three protrusions (see FIG. 2). Thus, it is possible to find the optimum position that is most vertically mounted while shifting by 40 (= 360/9) degrees, finer than the bearing holder illustrated in FIG.

  FIG. 5 is a detailed view for explaining the mounting of the bearing holder to the mounting plate, which is the same as that illustrated in FIG. On the other hand, FIG. 6 shows an example in which a protrusion by burring is provided in the flange portion of the bearing holder, and a corresponding through hole is provided in the mounting plate. Thus, the protrusion can be provided on either the mounting plate or the flange of the bearing holder, and a through hole can be provided on the other side.

  FIG. 7 shows an example in which protrusions formed by boss processing having a tip bag shape without a through hole like burring processing are provided on the mounting plate. Similar to the burring process described above, such protrusions can also be provided on the bearing holder. And similarly, after adjusting the inclination of the bearing holder and inserting the protruding portion into the through hole, it can be fixed by caulking from the leading end side of the protruding portion.

  FIG. 8 is a diagram for explaining the perpendicularity correction processing of the bearing holder formed by drawing. As described above, it is possible to adjust the position of the bearing holder to an optimum position where the inclination of the bearing holder can be offset with respect to the inclination of the mounting plate while shifting the mounting position. The perpendicularity can be corrected by cutting the back surface of the flange portion of the bearing holder (the surface in contact with the mounting plate) with a cutting tool. In addition, the two methods (adjusting and caulking and cutting) can be combined. However, this correction process can be applied to the bearing holder side provided with a through hole as illustrated in FIG. 3, but cannot be applied when a protrusion is provided on the back surface of the bearing holder.

  As described in the prior art with reference to FIG. 10, when the entire bearing holder is formed by cutting, it is necessary to use a relatively soft metal such as brass. Therefore, even a metal harder than brass such as a galvanized steel sheet can be cut.

  The squareness correction illustrated in FIG. 8 shows an example in which the back surface of the flange portion is corrected at a right angle with respect to the inner surface of the cylindrical portion of the bearing holder, whereas the squareness correction illustrated in FIG. This shows an example in which the squareness is corrected with reference to the inner surface of the bearing inserted inside.

It is a figure which shows the small motor which embodies this invention, and is a front view which shows a right half in cross section. It is a perspective view which takes out and shows only an attachment plate. It is a perspective view which takes out and shows only a bearing holder. It is a figure which shows another example of a bearing holder, and is the top view seen from the ceiling part side. It is detail drawing for demonstrating attachment of the bearing holder to a mounting plate. It is a figure which shows the example which provided the through-hole corresponding to it while providing the projection part by a burring process in the flange part of a bearing holder. It is a figure which shows the example which provided the projection part formed not by burring but by the boss process on the attachment plate. It is a figure explaining the perpendicularity correction process of the bearing holder formed by drawing. It is a figure which shows the example which corrects a squareness on the basis of the inner surface of the bearing inserted in the inside of a bearing holder. It is a figure which illustrates the 1st prior art which fixes a bearing device perpendicularly with high accuracy. It is a figure which illustrates the 2nd prior art which fixes a bearing device perpendicularly with high accuracy. It is a figure which illustrates the 3rd prior art which fixes a bearing device perpendicularly with high accuracy.

Claims (7)

In the cantilever bearing mechanism that has a thrust receiver and an oil-impregnated bearing inside, rotatably supports the end of the rotor shaft of the outer rotor type motor, and is fixed to the mounting plate,
By drawing from a high permeability steel plate, there are a flange portion, a cylindrical portion that is vertically raised from the center of the flange portion, and holds the oil-impregnated bearing inside, and an opening through which the shaft is inserted. A bearing holder that is formed integrally and continuously with the opened ceiling part,
One of the mounting plate and the bearing holder is provided with through holes at equal intervals on the circumference, and a plurality of protrusions formed by burring or boss processing on the other side are inserted into the through holes. After fixing the tip end side of the projection by caulking, the bearing holder was attached to the mounting plate,
Cantilever bearing mechanism. The ceiling portion has an outer surface facing inward at a right angle from the cylindrical portion opposed to the outer surface of the attracting magnet so as to function as a magnetic path of the attracting magnet, while supporting the retaining washer on the inner surface of the ceiling portion. Item 3. The cantilever bearing mechanism according to item 1. 2. The mounting plate is provided with a recessed portion having an inner diameter sufficient to allow a part of the oil-impregnated bearing to enter, and the bottom portion of the shaft is supported by a thrust receiver provided at the center of the bottom portion of the recessed portion. Cantilever bearing mechanism. The cantilever bearing mechanism according to claim 1, wherein the number of the through holes is an integral multiple of the number of the protrusions. A cantilever bearing mechanism that has a thrust receiver and an oil-impregnated bearing inside and supports the end of the rotor shaft of the outer rotor type motor in a rotatable manner by positioning it vertically with respect to the mounting plate. In the manufacturing method of
By drawing from a high permeability steel plate, there are a flange portion, a cylindrical portion that is vertically raised from the center of the flange portion, and holds the oil-impregnated bearing inside, and an opening through which the shaft is inserted. A bearing holder consisting of an open ceiling part is integrally formed continuously,
Either one of the mounting plate and the bearing holder is provided with equidistant through holes on the circumference,
On the other of the mounting plate and the bearing holder, a plurality of protrusions are formed by burring or bossing,
After correcting the perpendicularity of the bearing holder with respect to the mounting plate and inserting the protrusion, the tip side of the protrusion is fixed by caulking, and the bearing holder is attached to the mounting plate.
A method of manufacturing a cantilever bearing mechanism comprising: The method for manufacturing a cantilever bearing mechanism according to claim 5, wherein the number of the through holes is an integral multiple of the number of the protrusions. The correction of the perpendicularity of the bearing holder is performed by cutting the back surface of the flange portion before attaching to the mounting plate, or by adjusting the relative angular position of the bearing holder with respect to the mounting plate. The method for manufacturing a cantilever bearing mechanism according to claim 5, wherein the perpendicularity is corrected by inserting the protrusion into the through hole.

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