JP4013485B2 - Shaft insertion device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shaft insertion device for inserting and fixing a shaft into a hole of an object by shrink fitting, specifically, a fixed shaft (rotor) of a spindle motor and the fixed shaft (rotor). The present invention relates to a shaft insertion device with a flange that is inserted and fixed in a hole by shrink fitting.
[0002]
[Prior art]
The recording density of HDDs (hard disk drive devices) has doubled in recent years, and the number of tracks per inch (TPI) is 25000 TPI in current notebook computers. In the future, a higher density is required, and it is necessary to further increase the recording density on a limited size disk. By the way, TPI is an index for increasing the recording density. In the current mainstream ball bearings, the rolling elements rotate while being in point contact with the inner ring or the outer ring. In particular, a fluctuation “NRRO” (asynchronous fluctuation, hereinafter referred to as NRRO) from a perfect circle occurs, and the limit of TPI is starting to be seen.
[0003]
When this NRRO is large, deviation occurs from the track width of the disk (off-track), and a phenomenon such as generation of noise in the signal or inability to read data occurs.
[0004]
By the way, NRRO must be suppressed to 1/10 or less of the track width. For example, at a track width of 30000 TPI, it is 0.8 μm, and therefore, NRRO needs to be 0.08 μm or less. If a fluid bearing is used, NRRO can be suppressed to 0.04 μm or less, but a ball bearing cannot be used at about 0.08 μm. Therefore, fluid bearings have attracted attention in place of ball bearings, and the development competition of HDD motors using these fluid bearings has been spurred.
[0005]
On the other hand, along with miniaturization of devices, HDDs (hard disk drive devices) as means for recording information are further miniaturized and thinned. And the rotational drive part which is the heart part of this type of device has both a bearing and a motor part built in the drive hub, and by attaching a plurality of recording / reproducing disks on the outer periphery of the drive hub, The size of the device is reduced and the storage capacity is increased. Further, in order to increase the recording density, it is necessary to dramatically increase the accuracy of the rotating main shaft portion.
[0006]
Here, this type of spindle motor having a hydrodynamic bearing structure will be described with reference to FIG.
[0007]
As shown in FIG. 11, a fixed shaft 1 is fixed on a disk-shaped base 2, and a core 4 around which a winding 3 is wound is fixed on an upper surface. On the outer peripheral surface of the fixed shaft 1, radial direction dynamic pressure generating grooves (herringbone grooves) 1a and 1b are formed, which are spaced apart in the axial direction. Reference numeral 5 denotes a hub assembly including a hub 6 which is a disc fixing portion made of aluminum and a bronze sleeve 7 which is press-fitted into the inside thereof by shrink fitting or the like, and the sleeve 7 is inserted into the fixed shaft 1. As a result, the hub assembly 5 is rotatable about the fixed shaft 1.
[0008]
The sleeve 7 is formed with an oil reservoir 7a serving as a recess on a surface corresponding to the interval between the radial direction dynamic pressure generating grooves 1a and 1b. The radial direction dynamic pressure generating grooves 1 a and 1 b may be formed in at least one of the fixed shaft 1 and the sleeve 7. In addition, 8 is a screw which fixes the printed circuit board 9 with which the drive circuit components etc. which are arrange | positioned on the base 2 are mounted.
[0009]
A plurality of aluminum disks 10, 10 are attached to the outer periphery of the hub 6 via spacers 11, and these disks 10, 10 are fixed to the hub 6 with screws 13 via fixing plates 12. The yoke 14 fixed to the lower portion of the hub 6 is disposed at a predetermined interval so as to be surrounded by an annular recess 2 a formed in the base 2, while the core 4 is disposed on the inner surface of the yoke 14. A magnetic circuit is formed by fixing the magnet 15 with a predetermined interval.
[0010]
Further, a disc-shaped flange 16 bulging from the shaft diameter is fixed to the upper end portion of the fixed shaft 1 by means such as screws or press fitting, so that a cut formed on the outer peripheral surface of the flange 16 and the hub 6 is formed. An upper oil reservoir space 17 is formed between the notch 6a (FIG. 12 shows an a portion enlarged).
[0011]
Then, a thrust plate 18 serving as a mounting body is disposed on the flange 16, and the shaft portion is sealed by fixing the thrust plate 18 to the hub 6 with screws 19. The bearing portion configured in this manner includes a thrust direction dynamic pressure generating groove 18a, such as a pumping groove or a herringbone groove formed on the lower surface of the thrust plate 18, the upper oil reservoir space 17, and the radial direction dynamic pressure generating grooves. The bearings are lubricated by filling and applying a lubricant 20 such as oil or grease in the grooves 1a and 1b.
[0012]
As shown in FIG. 12, when the gap between the upper oil reservoir spaces 17 is small, the filled lubricant 20 rises up to the thrust plate 18 due to capillary action and scatters to the outside. Invite. Conversely, if the gap between the upper oil reservoir spaces 17 is too wide as shown in FIG. 13, the contact area between the lubricant 20 and the air becomes large, and the lubricant is reduced in the same manner as described above due to evaporation of the lubricant.
[0013]
In this assembled state, the magnet 15 and the yoke 14 are located on the upper side with respect to the magnetic center of the core 4 which is a magnetic body, so that an attractive force (Pz) acts on the hub assembly 5. , It is always drawn toward the base 2 side.
[0014]
The spindle motor configured as described above generates a magnetic field by energizing the winding 3, and the hub assembly 5 is rotated in a predetermined direction together with the magnet 15. During this driving, the sleeve 7 is centered with respect to the fixed shaft 1 by the pumping force of the radial direction dynamic pressure generating grooves 1a and 1b, and in the axial direction, the thrust direction dynamic pressure generating groove 18a of the thrust plate 18 is provided. As a result, the thrust plate 18 and the hub assembly 5 float several μm from the flange 16 integral with the shaft, and the hub assembly 5 rotates without contact with the fixed shaft 1 and the flange 16 via the lubricant 20. . A magnetic head (not shown) scans the disk 10 relatively in the radial direction to read / write information.
[0015]
By the way, the present situation is that the demand for high precision and high reliability is becoming increasingly strong for spindle motors used in information equipment such as HDDs (hard disk drive devices). As described above, when the flange 16 (for example, the thickness is 1.2 mm) for generating the dynamic pressure for supporting the rotation drive unit is attached to the fixed shaft 1, as shown in FIG. When fixing on the shaft end side, foreign matter 22 is sandwiched between the shaft end portion and the lower surface of the flange 16, or the perpendicularity between the fixed shaft 1 and the flange 16 cannot be maintained due to burrs or the like of the shaft end portion. This is a cause of deterioration of the function of the hydrodynamic bearing.
[0016]
As shown in FIG. 15, when the flange 16 is fixed to the fixed shaft 1 by press-fitting, the flange 16 is pressed onto the press-fitting surface of the flange 16 when the flange 16 is press-fitted to the fixed shaft 1 whose end is chamfered or rounded. The acting stress is small and non-uniform as it goes toward the shaft end where the press-fitting surface is reduced by chamfering or the like, so that the flange 16 is bent in the F direction and the flatness of the thrust bearing portion is deteriorated. This also causes a decrease in the reliability of the hydrodynamic bearing.
[0017]
Therefore, the applicant of the present invention has a base having a core around which a fixed shaft and a coil are wound, a rotatable hub that is fitted to the fixed shaft via a lubricant, and either the fixed shaft or the hub. And a dynamic pressure generating groove formed on one of the flange and the thrust plate sealing the flange. A spindle which solves such a problem by forming an annular recess on the press-fitting surface of either the fixed shaft or the disc-shaped flange press-fitted into the fixed shaft at a vertical position corresponding to the thickness of the flange. A motor application has been filed (see JP-A-8-322193).
[0018]
Hereinafter, the spindle motor according to the contents will be described with reference to FIGS. FIG. 16 is a half sectional view of an improved conventional spindle motor. The same components as those in the prior art are denoted by the same reference numerals, and detailed description of overlapping portions is omitted, and only changed portions are described below. To do.
[0019]
As shown in FIG. 16, the fixed shaft 1 is made of stainless steel (SUS303), and the sleeve 7 is made of bronze. The thermal expansion coefficients of both are substantially the same (17 × 10 −6 / ° C.). On the outer peripheral surface corresponding to the hub 6 made of aluminum, for example, on the side opposite to the inner surface of the sleeve 7 on the fixed shaft 1 side, the thickness (W₁Thickness equal to or sufficiently large (W)₂ Reinforcing sleeve 7)₁ Is fixed. This reinforcing sleeve 7₁ Is made of stainless steel (SUS430) having a thermal expansion coefficient of 10 × 10 −6 / ° C. smaller than the thermal expansion coefficient of the fixed shaft 1 and the sleeve 7. It is fixed by fixing means such as press fitting.
[0020]
Further, the sleeve 7 is a reinforcing sleeve 7.₁ For example, the sleeve 7 and the reinforcing sleeve 7 are fixed by shrink fitting.₁ By configuring the sleeve portion, the substantial thermal expansion coefficient of the sleeve portion is set to be lower than the thermal expansion coefficient of the fixed shaft 1. For this reason, the influence of the change of the clearance gap by the heat | fever of a dynamic pressure generation part is made small.
[0021]
For example, as a method for fixing the flange 16 having a thickness of 1.2 mm to the fixed shaft 1 having a shaft diameter of 3 mm, a press-fitting method is employed. That is, as shown in FIG. 17, annular recesses 23 a and 23 b are respectively formed in the upper and lower surface positions on the inner peripheral portion 16 a that is the press-fitting surface of the flange 16. The depths t of the annular recesses 23a and 23b are uniform, 0.1 mm in this embodiment, and the diameter is about 0.03 mm larger than the diameter of the inner peripheral portion 16a.
[0022]
Therefore, when the flange 16 is press-fitted into the fixed shaft 1, the stress (surface pressure) generated in the inner peripheral portion 16a with respect to the geometric center l of the flange 16 is symmetrical (position L1 = L2 vertically symmetrical with respect to the center l). And uniform, and the perpendicularity and flatness of the flange 16 with respect to the fixed axis 1 can be kept good.
[0023]
18 shows a mode opposite to the mode of FIG. 17, and its geometric center l is set so as to correspond to the inner peripheral portion 16a which becomes the press-fitting surface of the flange 16 on the fixed shaft 1 side. On the other hand, annular recesses 24a and 24b are respectively formed at upper and lower positions. Therefore, as in the above-described embodiment, the stress (surface pressure) generated on the press-fit surface is symmetric and uniform, and the perpendicularity and flatness of the flange 16 with respect to the fixed shaft 1 are improved. Therefore, in both embodiments, the reliability of the hydrodynamic bearing is improved, and a small and highly accurate and highly reliable motor with little vibration can be obtained.
[0024]
By the way, according to the technique described in JP-A-8-322193, the assembly of the shaft 1 to the flange 16 is performed by press-fitting, for example. When the both are assembled by this press-fitting, the inner periphery 16a and the shaft end 1d of the flange 16 are inserted into the inner peripheral portion 16a and the shaft end 1d as described above with reference to FIG. Chamfering is required as a guide for this.
[0025]
According to the method in which the fixed shaft 1 is attached to the flange 16 and press-fitted in this way, the apparatus can be easily configured because the flange 16 does not need to be heated. However, the plastic deformation of the hole portion of the flange 16 is possible. Therefore, it is difficult to maintain accuracy and strength. In addition, there is a method of attaching both of them by bonding, but according to this method, steps such as application and drying of the adhesive are required, and the complexity of the apparatus is inevitable.
[0026]
Therefore, as a result of studying the mounting method, chamfering, etc., the present applicant has found that the former is the most effective method of fixing by shrink fitting, and the latter has only chamfering. However, as will be described later, the size of the chamfer at the tip 43d of the shaft 43 and the inner peripheral portion (hole) 52a of the flange 51, the positional relationship between the two after assembly, and simply both are assembled. Instead, they need to be assembled with a predetermined assembling force, and it has been found that each is important.
[0027]
In other words, shrink fitting is a method in which a disc is heated and a shaft is inserted between them to fix it with a tightening force due to shrinkage of the hole diameter accompanying cooling, which involves plastic deformation of the hole, such as press fitting. This is because the desired assembly force can be easily obtained. The present invention has been made on the basis of such knowledge. When the shaft 43 is inserted into the inner peripheral portion 52a of the flange 51, it is carried out by shrink fitting, which is the above-mentioned predetermined runout accuracy and flatness. The present invention intends to provide a shaft insertion device in which the respective constituent members are arranged so as to be obtained as an assembling force. Hereinafter, this point will be described in comparison with this conventional shaft insertion device.
[0028]
Here, before entering the specific description of the shaft insertion device, FIG. 19 and FIG. 20 show the general relationship between the shaft and the hole during shrink fitting (the relationship between the margin and the assembling force). Use and explain. The tightening margin refers to the difference (D−d) between the diameter (D) of the shaft 1 and the hole diameter (d) of the hole (inner circumference) portion 16 a of the flange 16. The force which pulls out the flange 16 after assembling is said. Also, as a matter of course, since the assembly is performed by shrink fitting, by heating the hole diameter (d) of the inner peripheral portion 16a of the flange 16, the hole diameter (d) is expanded and the shaft 1 is inserted. The premise is that the two are combined by cooling. In the description of FIGS. 19 and 20, the chamfered portion is omitted for convenience.
[0029]
FIG. 19 (A) shows the state before shrink fitting, and is an explanatory diagram when the interference is small, that is, when the difference (D−d) between the two is small. The range in which the hole diameter (d) of the inner peripheral portion 16a of the flange 16 is expanded by heating is reduced. Accordingly, since the range of shrinkage is reduced during cooling, the assembly force G after shrink fitting (assembly) as shown in FIG.₁Is small. Note that FIG. 19A shows that the force H that tends to warp the flange 16 is reduced because the range in which the hole diameter (d) is expanded by heating is reduced.₁The flange 16 is less likely to warp. That is, as described later, although the required assembling force cannot be obtained, the contradictory result that the flatness of the flange 16 is easily obtained is obtained.
[0030]
On the other hand, FIG. 20A shows the state before shrink fitting, and is an explanatory diagram when the interference is large, that is, when the difference (D−d) between the two is large. As described above, the range in which the hole diameter (d) of the inner peripheral portion 16a of the flange 16 is expanded by heating is increased. Therefore, since the shrinkage range becomes large during cooling, the assembling force G after shrink fitting (assembling) as shown in FIG.₂Is great. In FIG. 20A, since the range in which the above-described hole diameter (d) is expanded by heating is increased, the force H for warping the flange 16 as shown in FIG.₂Therefore, the flange 16 is easily warped. That is, although the required assembling force described later is obtained, the contradictory result is obtained that the flatness of the flange 16 is difficult to obtain.
[0031]
[Problems to be solved by the invention]
Here, this type of conventional shaft insertion device will be schematically described. As a method for stably assembling a member having a hole and a shaft by shrink fitting, there is a technique described in JP-A-8-197341. This method is an invention for obtaining a concentricity between a drum shaft and an upper drum, and has a shaft holding means, a hole into which the shaft is inserted, and an object such as an upper drum having a heating means for heating the hole. An object holding means; an insertion means for relatively moving the shaft holding means and the object holding means to insert the shaft into the hole of the object; and the shaft held by the shaft holding means And alignment means for adjusting the coaxiality of the object held by the object holding means.
[0032]
Since the conventional shaft insertion device is an invention for obtaining the coaxiality of the drum shaft and the upper drum as described above, the flatness and the surface roughness of the upper drum are regarded as very important. No. That is, the technique described in Japanese Patent Laid-Open No. 8-197341 cannot be applied as it is to the shaft insertion device according to the present invention as described in detail below.
[0033]
As another method, there is a technique described in JP-A-8-184977 (cylindrical manufacturing apparatus). This method is a method of shrink fitting a member and a member to be shrink fitted while performing centering (coaxiality) adjustment and angle adjustment, and without shrinking the finishing accuracy of the member. It is something to try. However, because of its structure, it is not suitable for assembling parts with submicron accuracy intended by the present invention.
[0034]
According to the shrink-fitting method in such a conventional cylindrical body manufacturing apparatus, the end portion of the sleeve W2 is heated to expand the diameter, and then into the inner diameter processing hole 130 at the end portion of the sleeve W2 at the tip of the robot hand. After the gripping flange W1 is aligned and in a clearance fit state, the flange W1 is pressed to bring the outer peripheral portion 133 of the flange W1 into contact with the end surface 132 of the sleeve W2. However, in the technique described in Japanese Patent Application Laid-Open No. 8-184777, the flatness of the flange W1 can be obtained, but no consideration is given to the surface roughness, groove depth, etc. Further, like the technique described in Japanese Patent Laid-Open No. 8-197341, it cannot be applied as it is to the shaft insertion device according to the present invention as described in detail below.
[0035]
As described above, for spindle motors for HDDs, the use of fluid bearings is becoming mainstream due to the NRRO relationship. However, due to the reduction in NRRO, precise rotation accuracy as a spindle motor has been increased. It has been demanded. For this reason, it is necessary to finish the flatness, the surface roughness, the groove depth, etc. with higher precision as the thrust plate constituting the thrust bearing.
[0036]
Therefore, the flange 16 in contact with the thrust plate also needs to be finished to a predetermined flatness, and is generally desired to be finished to 1 μm or less. In addition, when the shaft 1 is used as a rotor instead of a stator, the deflection accuracy with respect to the shaft 1 needs to be finished to 1 μm or less like the above-described flatness for the above-described reason.
[0037]
Also, the assembly force is required to be 1000 N or more based on the results of various experiments and data of this type of HDD spindle motor currently supplied to the market. The reason for this is that if it is less than this, a deviation occurs at the time of start and stop due to a change with time or the like.
[0038]
Furthermore, if the tightening margin is too large or too small as described above, there is a contradictory result due to the relationship between the force for bending the flange and the assembling force. Therefore, as a result of examining the relationship between the above-described assembly force and various experimental results and data of this type of HDD spindle motor currently being supplied to the market, it is said that about 0.03 mm is necessary. I understood that.
[0039]
In other words, the assembly force of this type of HDD spindle motor must be 1000 N or more, and the tightening margin must be about 0.03 mm. Further, the flatness of the flange and the deflection accuracy with respect to the shaft 1 are each finished to 1 μm or less. It is something that needs to be.
[0040]
The present invention has been made in view of such a point, for example, by providing a shaft insertion device having a specific configuration for obtaining submicron squareness and flange flatness required for a rotor of a motor. This solves the above-mentioned problems.
[0041]
[Means for Solving the Problems]
  The present invention has been made in view of such points, and has the following configuration as means.
  That is, a shaft insertion device for assembling a shaft with a flange in which one surface of the flange is orthogonal to the shaft by inserting and fixing the shaft into the hole of the flange having a chamfered hole by shrink fitting,
  Shaft holding to hold the shaft in the vertical directionPartWhen,
  The flangeOn the other side of the flangeHolding flange support and,
  Shaft insertion means for causing the shaft holding portion to approach the flange support portion and inserting the shaft into the hole;
  An angle adjustment base for supporting the flange support portion movably in the horizontal direction;
  A cradle that supports the lower surface of the angle adjustment base at one point so as to be tiltable;
  A mounting base that is positioned on the upper surface side of the angle adjustment base and restricts tilting of the angle adjustment base when the upper surface comes into contact;
  Pressing the cradle upward with a predetermined pressing force to bring the angle adjustment base into contact with the mounting baseMeans, and
  Until the shaft is inserted into the hole by a predetermined amount by the shaft inserting means, the angle adjusting base is brought into contact with the mounting base by the pressing means, and the tilt of the angle adjusting base is restricted,
in frontThe shaft is held when the recording shaft is inserted into the hole by a predetermined amount.In the departmentA surface facing the flange and one surface of the flange;ButIn close contactIsAndA pressing force against the predetermined pressing force from the shaft insertion means is transmitted to the angle adjustment base, and the contact between the angle adjustment base and the mounting base is released.Angle adjustmentbaseTilt ofButAcceptableBe doneConstitutionWasThis is a shaft insertion device.
[0045]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of the invention will be described with reference to the accompanying drawings. It should be noted that the examples described below are preferred specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise described, the present invention is not limited to these embodiments.
[0046]
FIG. 1 is a side view showing the entirety of the shaft insertion device according to the present embodiment, FIG. 2 is a schematic view of a main part of the shaft insertion device according to the present embodiment, an explanatory view showing a first state, and FIG. FIG. 4 is a schematic diagram showing the second state of the shaft insertion device, FIG. 4 is a schematic diagram showing the third state of the shaft insertion device, and FIG. FIG. 6 is a schematic diagram showing a fourth state of the main part of the shaft insertion device. FIG. 6 is a schematic diagram showing a main part of the shaft insertion device, showing an assembled state of the shaft and the flange. FIG. 7 is a process diagram showing the assembled state of the shaft and the flange.
[0047]
FIG. 1 is a preferred embodiment of a shaft insertion device 30 according to the present invention, and is a side view showing the whole device for inserting a rotor (a shaft with a disk) of a spindle motor into a hole of a thrust plate. 2 is a schematic diagram of a main part of the shaft insertion device according to the present embodiment and shows the first state (stationary state) described above. Hereinafter, a specific configuration of the present embodiment will be described with reference to FIGS. The shaft insertion device 30 is roughly composed of a shaft holding means 40, an object holding means 50, an alignment means 60, an angle adjustment means 70, and an insertion means 80.
[0048]
As described above, with the increase in the speed of the spindle motor, the rotor (shaft with flange) that controls the rotating portion, the thrust plate into which the rotor is inserted, and the like need to be assembled with higher accuracy. In particular, it is important from the above-mentioned NRRO relationship that the surface deflection (perpendicularity) of the flange with respect to the shaft, the flatness of the flange, and the assembly force between the shaft and the flange are high.
[0049]
Therefore, the shaft holding means 40 having the shaft 43 and the like which will be described later as the shaft of the rotor needs to be assembled with considerably high accuracy. By the way, as clearly shown in FIG. 2, the shaft holding means 40 is connected to a slide member 41 connected to an insertion means 80 described later, a floating joint 48 attached to the slide member 41, and the floating joint 48. The base plate 49, the shaft holder 42 connected to the base plate 49, the shaft 43 inserted into the center hole 46 of the shaft holder 42, and the like are roughly configured.
[0050]
The lower surface 44 of the shaft holder 42 is finished to have a flatness of 0.3 μm or less and the squareness between the shaft 43 and the lower surface 44 is 1 μm or less for the reasons described above. The base plate 49 is provided with a suction hole (not shown), and this hole is connected to a vacuum pump (not shown).
[0051]
A fall prevention mechanism 47 is attached on the center hole 46 of the shaft holder 42 and on the upper surface 45 of the shaft holder 42 for sucking the shaft 43 by the vacuum pump and preventing the shaft 43 from dropping. The shaft 43 is sucked by the fall prevention mechanism 47 so as to protrude slightly from the lower surface 44 of the shaft holder 42.
[0052]
Further, a temperature adjusting mechanism (not shown) may be added to the shaft holder 42. This is because cooling at the end of shrink-fitting is performed by letting the heated later-described thrust plate 51, which is an object to be described later, escape to the shaft holder 42. Therefore, when used for a long time under a high temperature condition, the shaft holder 42 is used. This is because there is a possibility that the heat dissipation effect will be reduced.
[0053]
The object holding means 50 has, in advance, a flange 51 having a through hole 52 smaller than the shaft diameter of the shaft 43 by a tightening allowance in a central portion that is an object, a support base (heating block) 53 that supports the flange 51, In the center hole 54 of the support base 53 and in the through hole 52 at the center of the flange 51 described above, for example, a top member 55 made of a ceramic material, and also in the center hole 54 of the support base 53 described above, A spring member 56 that constantly presses the top member 55 in the upward direction (in the direction of the shaft 43 described above) and an outer peripheral portion of the support base 53 are provided at predetermined intervals to heat the flange 51 described above. Thus, the heating means 57 and the like for expanding the through hole 52 of the flange 51 are generally configured. In addition, 58 is a bracket that supports the heating means 57 described above, and 59 is a column that supports the bracket 58.
[0054]
The above-described support base 53 also needs to have a flatness of the upper surface 53a of 0.3 μm or less. The reason is that, as described above, on the upper surface 53a of the support base 53, the flange 51 having the through hole 52 in the center as the object and having a predetermined flatness (0.3 μm or less) is placed. This is because the squareness after assembly with the shaft 43 needs to be finished to 1 μm or less.
[0055]
As the heating means 57 that constitutes a part of the object holding means 50, the flange 51 that is the object to be heated is inserted into the core member 55 protruding from the support base 53, and the upper surface of the support base 53 described above. A high frequency induction heating unit that can be heated on the flange 51 in a non-contact manner so that the movement of the support base 53 on which the flange 51 is placed is not restrained when the flange 51 is placed on the 53a and heated. Is used.
[0056]
Thus, the flange 51 is not heated directly by high frequency induction heating, but the support 51 (heating block) 53 is heated, whereby the flange 51 is indirectly heated. This is because depending on the material of the flange 51, there is a material that is difficult to be heated by high-frequency induction heating. On the other hand, if the material is easily heated, the temperature rise time is shortened, which is convenient.
[0057]
In order to allow the flange 51 to be always set at the same position, as described above, the top of the flange 51 is mounted on the top member 53 set so as to protrude from the upper surface 53a of the support base 53. The through hole 52 is configured to be inserted from above. The top member 55 is configured to be pressed against the shaft 43 during assembly and to move down against the pressing force of the spring member 56.
[0058]
The aligning means 60 includes a table 61 on which the support base 53 is placed, a cradle (angle adjustment base) 63 provided on the lower surface of the table 61, and a space between the cradle 63 and the table 61. And a plurality of steel balls (or ceramic balls) 62 and a pair of horizontal clamping mechanisms 64 and 64 for preventing the table 61 from sliding in the horizontal direction.
[0059]
The horizontal clamp mechanism 64 uses, for example, a precision micrometer, and 65 is a steel ball fixed to the front end side of the horizontal clamp mechanism 64. Reference numeral 66 denotes a mounting base, and reference numeral 67 denotes a slide unit of the precision micrometer 64 mounted on the mounting base 66.
[0060]
The steel balls 65, 65 fixed to the distal ends of the pair of horizontal clamping mechanisms 64, 64 are in contact with the table 61 in the first state (when stationary) and at the end of assembly, and are in the initial position. The heating block 53 is returned, and when the shaft 43 and the flange 51 are assembled, the horizontal and tilt are freely set.
[0061]
The plurality of steel balls (or ceramic balls) 62a to 62n constituting the alignment means 60 are held by a holder (not shown) so that the steel balls are equidistant. With this configuration, the table 61 can move freely and smoothly even when a minute force is applied in the horizontal direction. Accordingly, the alignment means 60 can always exhibit a stable alignment function.
[0062]
The angle adjusting means 70 includes a steel ball 71 that supports the above-described cradle (angle adjustment base) 63 at a substantially central portion thereof, a cradle (joint) 72 that receives the steel ball 71, and supports the cradle 72. The air cylinder 73 is generally configured as a pressurizing unit. Reference numeral 74 denotes a support for supporting the mounting base 66 described above, and reference numeral 75 denotes a support member.
[0063]
The steel ball 71 of the angle adjusting means 70 is in contact with the above-described receiving base 63 at rest and when the assembly is completed, and the receiving base 63 is in contact with the above-described mounting base 66 and has an angle. Adjustment is not performed. When the shaft 43 and the flange 51 come into contact with each other, the horizontal clamp mechanism 64 is released from the clamp, so that the X₂The pressing force in the direction is transmitted to the support base 53, the table 61, the steel ball 62, and the receiving base 63, and the contact between the receiving base 63 and the mounting base 66 is released.
[0064]
Then, by releasing the clamp of the horizontal clamp mechanism 64 and releasing the contact between the cradle 63 and the mounting base 66, the angle adjusting means 70 can smoothly adjust the angle, and the lower surface of the shaft holder 42 that holds the shaft 43. 44 can be imitated completely in parallel. Further, as described above, the air cylinder 73 is attached to the lower portion of the cradle 72 as a mechanism for adjusting the pressing force at the time of assembly, so that the pressing force can be adjusted by the supply pressure thereof. The air cylinder 73 also has a function of pressing the unit of the heating block 53 against the horizontal reference plane so as to keep the horizontal at several μm when the heating block 53 is in the initial heating state.
[0065]
The insertion means 80 holds the slide member 41 that constitutes a part of the shaft holding means 40 described above, and is moved in the vertical direction (arrow X by the servo motor 82).₁~ X₂A slider 81 that slides in the direction), a guide member 83 that guides the vertical movement of the slider 81, a bracket 84 that holds the guide member 83, and the like. Reference numeral 85 denotes a bracket as a reinforcing member disposed between the slider 81 and the slide member 41 described above.
[0066]
Reference numeral 90 denotes a base member serving as a base for the guide member 83, the bracket 84, the support member 75 constituting the base portion of the angle adjusting means 70, and the bottom plate 93 that holds the support member 75. Reference numeral 91 denotes a top plate, and 92 denotes a guide shaft provided between the bottom plate 93 and the top plate 91 described above.
[0067]
Next, the operation of the above-described shaft insertion device 30 will be described with reference to FIGS. First, before entering the description of the operation of the shaft insertion device 30 according to the present embodiment, an outline of the assembly of the shaft 43 and the flange 51 will be described with reference to FIGS. 6 and 7.
[0068]
As described above, in the rotor of this type of spindle motor after assembly, the deflection accuracy of the flange 51 with respect to the shaft 43 is set to 1 μm or less, and the flatness of the flange 51 is set to 1 μm or less (see FIG. 6a). Further, the assembling force after assembling both is 1000 N or more (see FIG. 6b).
[0069]
Next, an assembly method will be described with reference to FIG. In the description of this assembling method, the chamfered portion is omitted for convenience. First, a flange 51 is prepared in which the flatness is finished to 1 μm or less, and the hole diameter 52 is finished to an interference fit diameter with respect to the shaft diameter of the shaft 43 (FIG. 7a). Next, the flange 51 is heated, and the hole diameter 52 of the flange 51 described above is expanded to a gap fitting diameter 52a with respect to the shaft diameter (FIG. 7b). Thereby, the shaft 43 can be inserted into the hole of the flange 51.
[0070]
Next, the shaft 43 is inserted into the hole of the flange 51, and then the heating to the flange 51 is stopped. By stopping the heating to the flange 51, the hole diameter that has been widened to the gap fit diameter 52a contracts and returns to the interference fit diameter. As a result, the deflection accuracy and assembly force of the flange 51 with respect to the shaft 43 are firmly fixed in a state where predetermined ones are obtained (FIGS. 7c and 7d).
[0071]
Here, on the premise of the assembling method described above, the operation of the shaft insertion device 30 according to this embodiment will be described with reference to FIGS. 1 to 5 and FIGS. 8 and 9 as necessary.
[0072]
1 and 2, in the stationary state (first state), as described above, the flatness of the upper and lower surfaces 51a and 51b is finished to a predetermined 1 μm or less, respectively, and the center portion is finished to an interference fit diameter. The flange 51 having the through-hole 52 is pushed upward by the spring member 56 in the center hole 54 of the support base (heating block) 53 by manual or appropriate transfer means, and slightly protrudes from the upper surface 53 a of the support base 53. The top member 55 is inserted from above.
[0073]
At the time of this insertion, as described above, the table 61 on which the support base (heating block) 53 having the flange 51 placed at a predetermined position is placed on the upper side, as described above, has a horizontal clamping mechanism (precision Since the movement in the horizontal direction is finely adjusted (initial adjustment to a predetermined position) by the micrometer (64) and fixed at the predetermined position, the two can be easily combined. Further, since the table 61 is fixed at a predetermined position in this manner, the heating to the flange 51 placed on the support base (heating block) 53 by the heating means 57 described later is surely performed. is there.
[0074]
As described above, when the table 61 on which the support base (heating block) 53 having the flange 51 placed at a predetermined position is fixed at a predetermined position, the heating means 57 applies the support base (heating block) 53 to the support base (heating block) 53. Predetermined heating is performed, and the through hole 52 of the flange 51 is expanded to the diameter of the clearance fit with respect to the shaft diameter. As a result, the shaft 43 can be inserted into the through hole 52 of the flange 51.
[0075]
In this first state, X by the shaft holding means 40 described above₂Since no pressing force is applied in the direction, the cradle 63 and the mounting base 66 remain in contact with each other, and therefore the angle adjusting means 70 is placed in a non-operating state. That is, angle adjustment is not performed.
[0076]
Next, the second state will be described with reference to FIG. As described above, in the first state, when the through hole 52 of the flange 51 is widened to a clearance fit diameter with respect to the shaft diameter, the flange 51 is attached to the shaft 43 when the shaft 43 is assembled. The horizontal clamp mechanism 64 is moved by the precision micro slide unit 67 so as to be smoothly inserted into the through hole 52 of the flange 51, and the clamp is released. As described above, since the plurality of steel balls 62a to 62n are arranged between the table 61 and the cradle 63, the table 61 can be easily moved in the horizontal direction.
[0077]
Even in this second state, the X by the above-described shaft holding means 40₂Since no pressing force is applied in the direction, the cradle 63 and the mounting base 66 remain in contact with each other, and therefore the angle adjusting means 70 is placed in a non-operating state. That is, no angle adjustment is performed.
[0078]
Next, the third state, that is, the assembly of the shaft 43 and the flange 51 will be described with reference to FIGS. 1 and 4. As described above, when the shaft 43 in the shaft holder 42 and the flange 51 are ready to be assembled, the servo motor 82 of the insertion means 80 operates. When the servo motor 82 is operated, as described above, the slide member 41 constituting a part of the shaft holding means 40 is held, and the servo motor 82 moves in the vertical direction (arrow X₁~ X₂The slider 81 that slides in the direction) moves along the guide member 83 that guides the vertical movement of the slider 81, for example, X₂Move in the direction.
[0079]
In this way, the insertion means 80 in which the shaft holding means 40 is connected by the slide member 41 is the X₂By moving in the direction, the floating joint 48 attached to the slide member 41, the base plate 49 connected to the floating joint 48, and the shaft holder 42 connected to the base plate 49 are both X.₂Move in the direction.
[0080]
Then, from the state shown in FIG. 3 before the shaft 43 in the shaft holder 42 is inserted into the through hole 52 of the flange 51 that is widened to the diameter of the clearance fit with respect to the shaft diameter, the shaft 43 is moved to the top. X against the pressing force of the spring member 56 against the member 55₂By pressing in the direction, the upper surface 51a of the flange 51 and the lower surface 44 of the shaft holder 42 are brought into close contact with each other as shown in FIG. When the shaft is inserted, the shaft 43 and the through hole 52 of the flange 51 are subjected to a predetermined chamfering (not shown), so that it is performed smoothly.
[0081]
In the insertion operation, the servo motor 82 is controlled to first bring the shaft holder 42 having the shaft 43 close to the flange 51 at a predetermined speed. Next, considering the case where the alignment is insufficient, the chamfer is slowly entered and alignment is performed. Then, after entering the chamfered portion, as described above, the flange 51 is cooled by heat conduction due to the close contact between the flange 51 and the shaft holder 42, and before the hole diameter of the through hole 52 of the flange 51 contracts, The shaft 43 is pushed to a predetermined position at a high speed.
[0082]
Specifically, the speed until the slider 81 connected to the shaft holder 42 or the like approaches the flange 51 is set to 1800 mm / min. Then, the chamfered portion slowly enters and the alignment speed is reduced to 50 mm / min to avoid inconvenience when alignment is insufficient. And the speed at the time of assembling both is rapidly increased to 9000 mm / min, and it pushes to a predetermined position, and an assembly is completed.
[0083]
In addition, the shaft 43 opposes the pressing force of the spring member 56 by the shaft 43 and X₂By pressing in the direction, the upper surface 51a of the flange 51 and the lower surface 44 of the shaft holder 42 are brought into close contact with each other, and this pressing force is transmitted to the table 61, the steel ball 62, and the cradle 63. 63 and the mounting base 66 are released from the contact state. Accordingly, the angle adjusting means 70 also shifts to a state where the non-operating state is solved at the same time and the angle is adjusted. That is, the angle adjustment with respect to the heating block 53 is performed via the steel ball 71, the cradle 63, the table 61, and the like. At this time, the heating by the heating means 57 is released.
[0084]
Therefore, if the square angle between the shaft 43 and the through hole 52 of the flange 51 (the deflection with respect to the shaft 43) is greater than or equal to a predetermined value, the angle is adjusted in this state and the angle is corrected to a predetermined angle. is there. That is, it is possible to follow the lower surface 44 of the shaft holder 42 holding the shaft 43 completely in parallel, and a predetermined runout accuracy can be obtained. In addition, when the pressing force by the air cylinder 73 is larger than a predetermined value at the time of this assembly, the pressing force is adjusted by the supply pressure of the air cylinder 73.
[0085]
Next, a 4th state, ie, the state after the assembly | attachment of the axis | shaft 43 and the flange 51, is demonstrated using FIG. As described above, when the predetermined assembly by shrink fitting is completed, the diameter of the flange 51 (through hole 52), which has been widened to the diameter of the clearance fit, contracts and returns to the diameter of the tight fit. Therefore, the flange 51 inserted into the shaft 43 is left as it is, and the above-described insertion means 80 is used as X₁Move in the direction. In response to the movement of the insertion means 80, the cradle 63 returns to its original position, and the cradle 63 and the mounting base 66 abut again. Further, the horizontal clamping mechanism 64 also returns to the original position, so that the horizontal clamping mechanism 64 again clamps the table 61 and returns to the initial position shown in FIG.
[0086]
Here, a specific example of assembling the fixed shaft and the flange of the spindle motor will be described with reference to FIGS.
[0087]
FIG. 8 is a partial view showing an assembled state of the fixed shaft and the flange of the spindle motor according to the present embodiment, and FIG. 9 shows an example of dimensions of the assembled state of the fixed shaft and the flange of the spindle motor according to the present embodiment. FIG. 10 is a partial view showing a bad assembled state of the fixed shaft and the flange of the spindle motor. The same parts as those in the conventional example are denoted by the same reference numerals, and detailed description thereof is omitted.
[0088]
FIG. 8 is a partial view showing an entire assembled state of the fixed shaft and the flange of the spindle motor. For example, the outer diameter of the flange 51 is 7.2 mm, the thickness of the flange 51 is 1.5 mm, and the shaft diameter 43 is 4 mm. In this case, the spindle motor is manufactured for the purpose of obtaining the above assembly force of 1000 N or more and the flatness of the flange of 1 μm or less.
[0089]
Example 1
Specifically, the tightening allowance is 0.03 mm, the chamfering amount of the edge portion 52 b of the flange hole 52 is 0.12 mm, and the chamfering amount of the chamfered portion 43 c formed on the tip 43 d side of the shaft 43 is 0.08 mm. The step between the upper surface portion 51a of the flange 51 and the upper surface portion 43d of the shaft 43 was set to 0.03 mm.
[0090]
As described above, the shaft 43 and the flange 51 are specifically configured, and both are assembled by shrink fitting with the shaft insertion device according to the present embodiment. As a result, the assembly force is 1100 N and the flatness of the flange is 0.062 μm. Obtained.
[0091]
(Comparative Example 1)
Under the same conditions as in Example 1 described above, only the chamfering amount of the chamfered portion 43c formed on the tip 43d side of the shaft 43 was set to 0.2 mm. As a result, the flatness of the flange deteriorated to 1.524 μm. FIG. 10 shows the results of Comparative Example 1 as a drawing. As is apparent from FIG. 10, the chamfered portion 43c formed on the tip 43d side of the shaft 43 has a large chamfering amount of 0.2 mm, so that it does not contact the shaft 43 when viewed from the flange 51 side. A portion (triangular zone Δ) occurs, and as a result, when the shaft 43 rotates at a high speed, a force that warps upward is generated on the upper surface 51a of the flange 51, and the balance is lost. . That is, the flange 51 is deformed.
[0092]
FIG. 9 shows the height after chamfering the edge 52b of the flange hole 52 as T.₁The height after chamfering of the chamfered portion 43c formed on the side of the top surface portion 51a of the flange 51 and the tip end portion 43d of the shaft 43 is T.₂T₁-T₂When the height relationship described above is set so as to satisfy the inequality of ≧ 0.01 mm and both are assembled by shrink fitting with the shaft insertion device according to the present embodiment, the flatness of the flange 51 is reduced to 1 μm or less. It was possible.
[0093]
【The invention's effect】
  According to the present invention,Shaft and flangeWhenCan be shrink-fitted with high accuracy and high strength. Further, the run-out between the shaft and the flange and the flatness of the flange can be reduced to 1 μm or less, and the pull-out resistance (assembly force) can be realized to be 1000 N or higher.
[Brief description of the drawings]
FIG. 1 is an overall view showing an embodiment of a shaft insertion device according to the present invention.
FIG. 2 is a schematic diagram of a main part of a shaft insertion device according to the present invention, and is an explanatory view showing a first state.
FIG. 3 is a schematic view of a main part of the shaft insertion device according to the present invention, and is an explanatory view showing a second state.
FIG. 4 is a schematic view of a main part of a shaft insertion device according to the present invention, and is an explanatory view showing a third state.
FIG. 5 is a schematic diagram of a main part of the shaft insertion device according to the present invention, and is an explanatory view showing a fourth state.
FIG. 6 is a schematic diagram of a main part of the shaft insertion device according to the present invention, and is an explanatory view showing an assembled state of the shaft and the flange.
FIG. 7 is a schematic diagram of a main part of a shaft insertion device according to the present invention, and is a process diagram showing an assembled state of a shaft and a flange.
FIG. 8 is a partial view showing an example of an assembled state of a fixed shaft and a flange of a spindle motor.
FIG. 9 is a partial view showing another example of the assembled state of the fixed shaft and the flange of the spindle motor.
FIG. 10 is a partial view showing a bad assembly state of the fixed shaft and the flange of the spindle motor.
FIG. 11 is a half sectional view showing an example of a conventional spindle motor.
12 is a half sectional view showing an oil reservoir space of the spindle motor of FIG.
13 is a half sectional view showing another oil pool space of the spindle motor of FIG. 11. FIG.
14 is a partially enlarged view showing a relationship between a fixed shaft and a flange in the spindle motor of FIG. 11. FIG.
15 is a partially enlarged view showing another relationship between the fixed shaft and the flange in the spindle motor of FIG. 11. FIG.
FIG. 16 is a half sectional view showing an example of an improved conventional spindle motor.
17 is a partially enlarged view showing a relationship between a fixed shaft and a flange in the spindle motor of FIG. 16;
18 is a partially enlarged view showing another relationship between the fixed shaft and the flange in the spindle motor of FIG. 16;
FIG. 19 is a partial view showing an example of an assembly process and an assembly state of the fixed shaft and the flange of the spindle motor.
FIG. 20 is a partial view showing an example of another assembling process and an assembling state of the fixed shaft and the flange of the spindle motor.
[Explanation of symbols]
30 axis insertion device
40 shaft holding means
41 Slide member
42 Shaft holder
43 axes
44 Bottom
45 Top
46 Center hole
47 Fall prevention mechanism
50 Object holding means
51 Thrust plate
52 Through hole
53 Support stand (heating block)
54 Center hole
55 Frame member
56 Spring member
57 Heating means
58 Bracket
59 prop
60 Alignment means
61 tables
62 Steel balls
63 cradle
64 Clamp mechanism
65 buffer
66, 67 Bracket
70 Angle adjustment means
71 steel balls
72 cradle
73 Air cylinder
80 Insertion means
81 slider
82 motor
83 Guide member
84 Bracket
85 Reinforcing member
90 Base member
91 Top plate
92 Guide shaft
93 Bottom plate

Claims (1)

A shaft insertion device that inserts and fixes a shaft into the hole of the flange having a chamfered hole by shrink fitting, and assembles a flanged shaft in which one surface of the flange is orthogonal to the shaft,
A shaft holding portion for holding the shaft in a vertical direction;
A flange support for holding the flange on the other surface side of the flange ;
Shaft insertion means for causing the shaft holding portion to approach the flange support portion and inserting the shaft into the hole;
An angle adjustment base for supporting the flange support portion movably in the horizontal direction;
A cradle that supports the lower surface of the angle adjustment base at one point so as to be tiltable;
A mounting base that is positioned on the upper surface side of the angle adjustment base and restricts tilting of the angle adjustment base when the upper surface comes into contact;
Pressing means for pushing up the cradle upward with a predetermined pressing force to bring the angle adjustment base into contact with the mounting base ;
Until the shaft is inserted into the hole by a predetermined amount by the shaft inserting means, the angle adjusting base is brought into contact with the mounting base by the pressing means, and the tilt of the angle adjusting base is restricted,
When the previous SL shaft is inserted a predetermined amount into the bore, the flange surface facing in the shaft holding portion and the one surface of the flange is in close contact Rutotomoni, pressing of the predetermined from the shaft insertion means shaft insertion, characterized in that the pressing force against the force has a structure in which contact is released the angle adjustment based tilting of the mounting base are transmitted the angle adjustment based on the angle adjustment base is allowed apparatus.

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