JPH0763213B2 - Bearing preload method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing preloading method, and more particularly to a bearing preloading method for fixing a bearing that rotatably supports a rotating body by applying a predetermined preload. .

[Outline of Invention]

The present invention relates to a method of applying a predetermined preload to a bearing that rotatably supports a rotating body, in which a predetermined pressure is applied in the thrust direction by a bearing or a member related to the bearing, and an adhesive is used in this state. The bearing is fixed in the thrust direction, which facilitates the work for adjusting the preload and reduces the variation in the preload.

[Conventional technology]

Bearings are widely used to rotatably support various types of rotating bodies. A general bearing is provided with a ball, and the ball is rotatably supported between an inner ring and an outer ring. A predetermined clearance is provided between the balls and the grooves of the inner and outer races. Therefore, if such a bearing is used as it is, the rotating body has a clearance in the thrust direction, which causes rattling in the thrust direction. Therefore, in a bearing used in a device that performs a precise operation, a preload is applied to this bearing in advance to remove the play in the thrust direction.

In the conventional method of applying a preload to a bearing, for example, a step is provided on the shaft, and a preload is applied to the inner ring of the bearing by a pressing member that abuts on this step. Alternatively, the stepped screw is formed on the shaft, and the inner ring of the bearing is pushed by the female screw member screwed to the screw. However, according to such a conventional preloading method, the pressure of the preload is determined by the position of the step portion. Therefore, unless the step portion is formed with high dimensional accuracy, the preload varies greatly.

In view of such drawbacks, a method of actually measuring the bearing loss to determine the preload is used. In this method, for example, a male screw is formed directly on the outer peripheral surface of the shaft, and a bearing loss is measured while screwing a female screw member that is screwed into the male screw, and the screw is locked when a predetermined bearing loss is reached. Therefore, a predetermined preload is applied.

[Problems to be solved by the invention]

However, in the conventional bearing preloading method as described above, it is necessary to tighten the screws while measuring the bearing loss for all the bearings, and thus there is a disadvantage that a large number of man-hours are required to adjust the preload. .
Further, even with such a method, the variation in the preload is not always reduced, and the variation in the preload amount occurs.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a bearing preloading method in which the number of work steps for adjusting the amount of preload is reduced and the preload varies little. It is a thing.

[Means for solving problems]

The present invention relates to a method of fixing a bearing that rotatably supports a rotating body by applying a predetermined preload to the bearing, wherein a predetermined pressure is applied to the bearing in a thrust direction by a pressing member attached to a support shaft of the bearing. In this state, the adhesive is injected and solidified in the groove formed in the inner peripheral side of the pressing member and facing the outer peripheral portion of the support shaft, and the adhesive is solidified under pressure in the pressing member. The present invention relates to a bearing preloading method, which is characterized in that it is fixed to a support shaft.

[Action]

A predetermined pressure is applied to the bearing in the thrust direction by a pressing member attached to the shaft of the bearing.
In the state where the pressure is applied in this way, the adhesive is injected into the groove formed in the inner peripheral side of the pressing member and facing the outer peripheral side of the support shaft to be solidified. Then, the pressing member is fixed to the support shaft in a state where pressure is applied.

〔Example〕

The present invention will be described below with reference to an embodiment shown in the drawings. 5 and 6 relate to a motor to which the preloading method according to the embodiment of the present invention is applied, and the motor includes a motor base 10. A boss 11 is formed at the center of the base 10, and a shaft 12 is press-fitted and fixed to the boss 11. A rotor boss 13 is rotatably attached to the shaft 12. That is, the rotor boss 13 has ball bearings 14 and 15 above and below it.
It is rotatably supported by the shaft 12 via. The outer ring of the upper bearing 14 is engaged with the step portion 16 of the rotor boss 13. Note that a step portion may be formed on the lower end side of the inner diameter of the rotor boss 13, and the step portion may be engaged with the edge of the upper end of the outer ring of the lower bearing 15.

A chuck portion 17 is integrally formed with the rotor boss 13 in a ring shape, and a chuck magnet 18 is held in a recess of the chuck portion 17. The upper end 19 of the chuck portion 17 projects above the upper surface of the chuck magnet 18, and a gap is formed between the center core of the recording medium and the chuck magnet 18.
This is because chucking is performed using the upper end 19 of the chuck portion 17 as a reference surface, and by making the dimensional accuracy of the reference surface 19 high, surface wobbling of the recording medium is prevented.

Further, a guide cap 20 is fixedly attached to the upper end of the shaft 12. An inclined portion 21 is formed on the outer peripheral side of the guide cap 20 to guide the mounting of the recording medium. The recording medium guided by the inclined portion 21 is further guided by the outer peripheral surface of the ball bearing 14, and the upper end portion of the ball bearing 14 has a chuck portion 17
The upper surface 19 of the above. Further, the edge of the upper end portion of the outer ring of the ball bearing 14 has a curved cross-sectional shape so as to protect the recording medium during mounting.

Next, explaining the structure of the rotor of this motor,
A rotor case 22 is fixed to the rotor boss 13 by press fitting. The rotor case 22 is attached to the rotor boss 13
It may be formed integrally with. The main magnet 23 is fixedly attached to the lower surface of the rotor case 22. Further, a gear 24 is formed on the outer peripheral side of the rotor case 22, and the output of the motor can be directly taken out by the gear 24. Further above main magnet
A rotor yoke 25 is arranged below 23. A boss portion 26 formed at the center of the rotor yoke 25 is fitted to the outer ring of the ball bearing 15 on the lower side, whereby the center position is determined. The rotor yoke 25 contacts the lower end of the rotor boss 13 and is held at this position by the attraction force of the main magnet 23.

A double-sided printed wiring board 27 is arranged in an axial air gap formed between the main magnet 23 and the rotor yoke 25. This printed wiring board 27 is screwed to the support 28.
It is designed to be installed by 29. The support base
Reference numeral 28 is made of a non-magnetic material, and is designed to prevent static coking due to the attractive force of the main magnet 23. The support base 28 is fixedly attached to the base 10 in which a notch 30 for mounting the motor is formed. Then, on the double-sided printed wiring board 27, an FG pattern is formed in addition to the pattern for wiring the coil, and a hall element for position detection is further attached. Further, on the printed wiring board 27, as shown in FIGS. 7 and 8,
Three coils 31, 32 and 33 are mounted at 120 degree intervals.

Next, the drive circuit for these coils 31, 32, 33 will be described with reference to FIG. 9. These coils 31, 32, 33 are connected to the power supply terminals via transistors 34, 35, 36, respectively. There is. Also these coils 31, 32,
33 is connected to the ground side via transistors 37, 38 and 39, respectively. Also transistor 34,
The base of 37 is connected to inverting amplifier 40, and transistor 3
The bases of 5 and 38 are connected to the inverting amplifier 41, and the bases of the transistors 36 and 39 are connected to the inverting amplifier 42. The input sides of the amplifiers 40 to 42 are connected to the logic circuit 46. The logic circuit 46 is connected to the Hall elements 43, 44, 45 that detect the rotational position of the rotor case 22 including the main magnet 23.

In the above configuration, the logic circuit shown in FIG.
The three Hall elements 43 to 45 connected to 46 detect the rotational position of the main magnet 23 supported by the rotor case 22, and supply the detection output to the logic circuit 46. ing. The logic circuit 46 forms three sine waves whose phases are shifted by 120 degrees from each other based on the detection of these three Hall elements 43 to 45, and supplies them to the inverting amplifiers 40, 41 and 42, respectively. ing. A sine wave with no delay is supplied to the first inverting amplifier 40, and a sine wave with a 120 ° phase delay is supplied to the second inverting amplifier 41. Then, a sine wave whose phase is delayed by 240 degrees is supplied to the third inverting amplifier 42.

Each of the three inverting amplifiers 40, 41, 42 amplifies the input sine wave and outputs it from the positive terminal as it is, and also inverts the input sine wave and outputs it from the negative terminal. That is, the first inverting amplifier 40
Supplies the amplified output of the logic circuit 46 with no phase delay to the base of the transistor 34, while the inverted sine wave is supplied to the base of the transistor 37. I have to. Similarly, the inverting amplifier 41 outputs the output delayed in phase by 120 degrees to the transistor 35.
Is supplied to the base of the transistor 38, and an inverted sine wave is supplied to the base of the transistor 38. Similarly, the inverting amplifier 42 supplies a sine wave whose phase is shifted by 240 degrees to the base of the transistor 36 and supplies the inverted sine wave to the base of the transistor 39.

One ends of the three coils 31, 32, 33 are connected to each other, and the other ends thereof are connected to the connection points of the transistors 34 and 37, the connection points of the transistors 35 and 38, and the transistors 36 and 39.
Are connected to the respective connection points. Therefore, these coils 31, 32, 33 are switched so as to be shifted from each other by 120 degrees to be energized, and the direction of current flow is reversed. Transistor
When the transistor 34 and the transistor 38 are turned on, a current flows from the power source side to the coil 31 through the transistor 34, and further this current flows to the ground side through the coil 32 and the transistor 38. On the other hand, the transistor 35 and the transistor
When 37 is electrically connected, a current flows from the power supply side in the order of the transistor 35, the coil 32, the coil 31, the transistor 37, and the ground, and the current direction is reversed from the above case.

In this way, the currents respectively flowing through the three coils 31, 32, 33 are linked to the magnetic flux generated by the main magnet 23 held in the rotor case 22, so that the rotor case 22
Will be rotated by the rotational force. In this way, a three-phase brushless motor with three coils, eight poles, and 120 degrees bidirectionally energized produces a rotational force.
The recording medium can be rotationally driven via 17 or can be taken out through the gear 24 provided in the case 22.

Next, a method of preloading the ball bearings 14 and 15 that rotatably supports the rotor boss 13 having the rotor case 22 will be described. This preload is performed as shown in FIG. That is, the rotor boss 13 is rotatably assembled to the shaft 12 via the bearing 14, and the guide cap 20 is attached to the upper end of the shaft 12. In this state, a pressing force 55 corresponding to a preload is applied from above as shown by the arrow, and in this state, the ultraviolet curable adhesive 47 is flown into the groove 59 formed between the shaft 12 and the guide cap 20. Put in. Then, a predetermined preload is applied to the bearing 14 by hardening the adhesive 47 while applying the pressing force 55.

When applying such a preload, for example, the device shown in FIG. 4 may be used. This device has a base 48, and a plurality of rods 49 are provided upright on the periphery of the base 48.
Are provided, and the through holes 51 of the pressing plate 50 are fitted to these rods 49. Therefore, the motor is placed on the base 48, the weight 52 is attached to the outer peripheral portion of the rod 49, and the weight 52 is added to the guide cap 20 of the motor via the holding plate 50. A transparent plate 53 made of acrylic resin is attached to the center of the holding plate 50, and
A pressing ring 54 is attached to the lower surface of the transparent plate 53, and the guide cap 20 is pressed by the pressing ring 54.

Therefore, the value of the preload is determined by the weight 52, and the amount of preload can be arbitrarily adjusted. Moreover, as shown in FIG. 4, when the weight 52 applies pressure to the guide cap 20, the ultraviolet curable adhesive 47 is poured into the groove 59 between the guide cap 20 and the shaft 12 to cure the adhesive. The goodness makes the task of preloading very easy. Furthermore, since the value of the preload is determined by the weight 52, the preload does not vary.

Next, a modified example of the above embodiment will be described with reference to FIG. In this modification, the guide cap 20 is fixed by using an anaerobic adhesive instead of the ultraviolet curable adhesive. That is, also in this modification, the pressing force 55 is applied from above as shown by the arrow, and the anaerobic adhesive 47 is poured into the gap 60 between the guide cap 20 and the shaft 12 to be cured. . So in this case,
It is not necessary to provide the transparent plate 53 on the device for preloading and to irradiate ultraviolet rays from above.

Next, another modification will be described with reference to FIG. The feature of this modified example is that a rubber ring 61 is interposed between the guide cap 20 and the upper end of the inner ring of the bearing 14, and the rubber 52 is applied by a pressing force 55 by a weight 52 applied from above. The adhesive 47 is poured into the groove 59 while the ring 61 is elastically deformed, and then the adhesive is cured. Therefore, in this case, the elastic restoring force of the rubber ring 61 elastically causes the bearing
Preload will be applied to 14. That is, the rubber ring 61 is attached in a state in which a preload is stored as elastic energy.

The present invention has been described above with reference to the embodiments and the modifications thereof.
The present invention is not limited to the above-described embodiments or modifications, and various modifications can be made based on the technical idea of the present invention. For example, as shown in FIG. 10, a rotor yoke
Attach the FG magnet 56 to the underside of the 25
The FG pattern printed circuit board 57 and the iron plate 58 may be attached to the upper surface of 10 to obtain the FG output.
By attaching the iron plate 58 in particular, it becomes possible to effectively guide the magnetic flux. Alternatively, as shown in FIG. 11, the positions of the coils 31 to 33 and the printed wiring board 27 may be reversed and the coils 31 to 33 may be attached to the upper surface of the printed wiring board 27.

〔The invention's effect〕

As described above, according to the present invention, a predetermined pressure is applied to the bearing in the thrust direction by the pressing member attached to the supporting shaft of the bearing, and in this state, the inner peripheral side of the pressing member and the outer peripheral portion of the supporting shaft. The adhesive is injected and solidified in the groove formed in the portion facing the core, and the pressing member is fixed to the support shaft under pressure.

Therefore, the pressing member is fixed to the support shaft in a state where pressure is applied, and thus the bearing is fixed via the pressing member in a state where preload is applied in the thrust direction. If the above pressure is obtained by using a weight, for example, the workability for applying the preload is significantly improved, and the variation in the preload amount can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a preloading operation according to an embodiment of the present invention, FIG. 2 is a vertical sectional view showing another preloading operation, and FIG. 3 is a vertical sectional view showing yet another preloading operation. Fig. 4 is a vertical sectional view of a device for preloading, Fig. 5 is a plan view of a motor using this preloading method, Fig. 6 is a vertical sectional view of the same, and Fig. 7 is a printed wiring holding a coil. FIG. 8 is a plan view of the substrate, FIG. 8 is a side view of the same, FIG. 9 is a circuit diagram of a motor drive circuit, FIG. 10 is a longitudinal sectional view of a motor according to a modification, and FIG. 11 is a motor according to another modification. FIG. In the drawings, reference numerals 12 ... Shaft 13 ... Rotor bosses 14, 15 ... Ball bearing 20 ... Guide cap 47 ... UV curable adhesive 55 ... Pressing force.

Claims (1)

[Claims] 1. A method of fixing a bearing that rotatably supports a rotating body by applying a predetermined preload to the bearing, wherein a predetermined pressure is applied to the bearing in a thrust direction by a pressing member attached to a support shaft of the bearing. In this state, the adhesive is injected and solidified in the groove formed in the inner peripheral side of the pressing member and facing the outer peripheral portion of the support shaft, and the pressure is applied to the pressing member. A bearing preloading method, wherein the bearing is fixed to the support shaft.