JPS6069320A - Shaft unit with bearing - Google Patents

Abstract

PURPOSE:To balance thrust pressure by disposing a rotatable flange member and a spring member interposed between the flange member and an outer race member at the middle position of a concave groove portion of a shaft having ball bearing concave grooves at both ends thereof. CONSTITUTION:When a shaft is subjected to upward force, force is worked upon a shaft 1' in direction of an arrow A. Therefore, an upper outer race 2 is displaced in the arrow direction, and the spring force of a coiled spring 81 is set larger than the spring force of a coiled spring 82 not to produce a gap between a ball bearing concave groove 1'a and 2a. If the spring force 81 is equal to the spring force 82, a ball bearing concave groove 1'c and a flange 9 are disposed at a position a little biased to the upper outer race 2 side, whereby even if upward force is worked upon the shaft 1', pressure applied to the upper and lower bearing balls 4, 5 van be kept well-balanced.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a shaft unit with a bearing,
In particular, the present invention relates to a shaft unit with a bearing that can balance the pressure applied to bearing poles provided at both ends of the shaft even if a force is applied to either one of the thrust directions of the shaft.

(Background Art) For example, in a video tape recorder, a rotating drum unit is arranged in the tape running path, a rotating magnetic head is arranged inside this drum unit, and the magnetic tape is scanned by this rotating magnetic head. , recording or reproducing signals.

In this rotating drum unit, for example, normally 1
, 800 rpm or 1.500 rpm, and a multi-rotation magnetic head is rotated by this rotating drum.

The width of the recording track formed on the magnetic tape is narrow, ranging from 20 μm to several tens of μm, and considering tape compatibility, the mounting of the rotating magnetic head must be highly accurate. . Furthermore, if the amount of protrusion of the rotating magnetic head from the outer peripheral surface of the rotating drum exceeds a predetermined value, the magnetic tape will be vibrated, whereas if it is less than a predetermined value, contact with the magnetic tape will be insufficient. However, since this causes deterioration in recording and reproducing performance, extremely high rotational accuracy and assembly accuracy of the rotating drum unit are required.

Therefore, in conventional rotating drum units, the rotating shaft of the rotating drum is generally made of stainless steel, and this shaft is supported by two ball bearings installed at both ends of the rotating drum. In order to control the radial and thrust vibrations that occur during rotation of the drum, preload was applied to each of the two pole bearings.

As mentioned above, since a high degree of rotational precision is required for rotating drum units for video tape recorders, the diameter of the inner diameter of the inner ring of the ball bearing and the outer diameter of the shaft that is press-fitted into it is The inner diameter of the inner ring and the outer diameter of the shaft of the manufactured goal bearings were individually measured so that the difference was within 1 to 2 μm, and those that fell within the above diameter difference were selected. .

Furthermore, in order to suppress the deflection in the radial direction and the thrust direction of the rotating drum, for example, after applying preload to the pg-roll bearing by the transformer stand and the lower pedestal, the rotating drum equipped with the rotating magnetic head is The mating surface that mates with the transformer stand was post-processed using a lathe, etc. to improve the rotational accuracy of the rotating drum.

In this way, the assembly of a conventional rotating drum unit is
? - Since it is necessary to measure the inner diameter of the inner ring and the outer diameter of the shaft of the bearing, selection work, and post-processing, an increase in manufacturing costs cannot be avoided, and the rotation accuracy of the rotating drum cannot be avoided. There were limits to improvement.

By the way, a shaft unit with a bearing as shown in FIG. 1 has been proposed.

In Figure 1, 1 is the goal bearing? - The shaft 4 and the shaft 5 each have a plurality of pair ringer mails, and the pole receivers 2 and 3 are outer rings having concave grooves 2a and 3a. The outer diameters of the outer rings 2 and 3 are different from each other in consideration of workability of the press-fit cap when assembling the shaft unit to the device. Coil springs 8 for applying preload are interposed between the outer rings 2 and 3, respectively, to suppress vibrations of the ball bearing in the radial direction and in the thrust direction. 6 and 7 are receiving members for the coil gune 8.

When a shaft unit with a bearing having the above-mentioned configuration is used in a rotating drum unit for a video tape recorder, the inner ring of the ball bearing is eliminated, and only the bearing of the ball bearing is used. −
Since the pitch circle of the rotary drum unit will be moved inside the rotating shaft, the starting torque and normal load torque required to rotate the rotating drum will be reduced, thus reducing the load on the motor that rotates the rotating drum of the rotating drum unit. As a result, it is possible to save power. Also, if the outer diameter of the outer ring of the goal bearing attached to the rotating shaft is constant, what will happen? - By eliminating the inner ring of the ball bearing, the diameter of the bearing ball can be increased by the thickness of the inner ring, increasing the load capacity of the ball bearing, and therefore reducing the resistance to temperature changes. yl? - Even if the preload on the wheel bearing changes, it will not wear out.It is possible to extend its life and improve its rotation accuracy. Furthermore, in the conventional one? - Since the inner diameter of the inner ring of the ball bearing and the ball receiver provided on the inner ring can eliminate eccentricity errors caused by machining errors with the concave groove, the radial runout of the rotating drum of the rotating drum unit can be greatly reduced. The rotational accuracy of the rotating drum unit can be greatly improved. In addition, the inner diameter of the inner ring of the sol bearing and the outer diameter of the shaft are respectively measured and selected so that the diameter difference between the inner diameter of the inner ring of the ball bearing and the outer diameter of the shaft is within the range of 1 to 2 μm, The work process of combining can be omitted.

Since the ball bearing, shaft and preload coil spring are integrated as a unit, the rotating drum
When assembling the unit, it can be handled as a single component, which improves work efficiency.In particular, by inserting a coil spring between the outer ring of the sol bearing, the sol bearing can be assembled in advance.
Because the bearing is preloaded, it offers many advantages over conventional bearings, such as greatly improved workability.

Here, as a rotating drum unit for a video tape recorder, a drum unit using a "surface facing type motor" configuration in which the rotor and stake of the rotating drum driving motor are arranged along the rotation axis is used. A shaft unit with a bearing will be described with reference to FIG. 2.

Components shown in the figure with reference numbers 1 to 8 are:
Since it is the same as that shown in FIG. 1, its explanation will be omitted.

11 is a fixed drum of a rotating drum unit having a tape running surface 11h and supporting a shaft unit with a single bearing; 12;
is a rotating drum having a plurality of rotating magnetic heads 13, and is fixed to the shaft 1 together with a transformer stand 14. 15& and 15b constitute a rotary transformer which transmits and receives signals for recording or reproducing video signals and the like on the magnetic tape via the rotating magnetic head 13 without contact.

16 and 17 are rotor magnets and stator coils that constitute a motor for rotationally driving the rotating drum 12, and the rotor magnet 16 is a rotor support member fixed to a lower pedestal 18 attached to the lower end of the shaft 1. 19, while the stator
The coil 19 is attached to a stator support member 20 fixed to the lower end of the fixed drum 11, facing the rotor magnet 16.

The upper outer ring 2 of the shaft unit is fixed to the central through hole 11b of the fixed drum 11 by a fixing means such as press fitting, shrink fitting, or adhesive, and the lower outer ring 3 is simply fixed to the central through hole 11b of the fixed drum 1. By fitting them together, the preload forces applied by the coil spring 8 to the outer rings 2 and 3 are balanced. In the shaft unit installed in this manner, the magnetic attraction force generated between the rotor magnet 16 and the stator coil 17 during rotation of the motor 16, 17 causes the fixed drum 11 to be displaced downward and Since the outer ring 2, which is press-fitted, shrink-fitted, or glued into the central through-hole 11b of the fixed drum 11, is also displaced downward, the shaft 1 receives an upward force (in the direction of the arrow). Therefore, it is clear from the positional relationship between the illustrated lower bearing sole 5 and the ball holder with the grooves 1b and 3a, and the positional relationship between the upper bearing ball 4 and the ball holder with the grooves 1a and 2a. , the pressure on the lower bearing ball 5 increases, while the pressure on the upper bearing ball 4 decreases. As a result, the pressures applied to the upper and lower earring soles 4 and 5 become unbalanced. This means that although there is no gap between the lower bearing sole 5 and the ball receiver grooves lb and 3a,
There is no gap between the upper bearing sole 4 and the pawl grooves 1a and 2a, so the shaft 1 rotates while generating vibration in the direction of Since the drum 12 rotates in conjunction with precession, there is a disadvantage that the accuracy in the height direction of the rotating magnetic head 13 cannot be guaranteed during rotation.

The present invention has been made in view of the above-mentioned circumstances, and is a shaft with a ball bearing having a plurality of outer ring members.
In the unit, a new bearing configuration that allows the pressure applied to each bearing ball to be maintained in a balanced state even when a force is applied to the shaft in one of its thrust directions. The purpose is to provide a shaft unit with a

Another object of the present invention is to provide a shaft unit with a bearing in which the preload forces on the respective outer ring members can be made different in advance.

Still another object of the present invention is to provide a rotary motor for a video tape recorder using a configuration of a face-to-face motor in which the rotor and stator of the motor for driving a rotatable member are arranged along the axis of rotation. It is an object of the present invention to provide a shaft unit with a bearing that is suitable for the unit and has a novel configuration in which the above-mentioned shaft deflection in the radial direction is less likely to occur.

(Explanation based on Examples) Hereinafter, the means taken in the present invention to achieve the above-mentioned object will be exemplified and explained based on Examples.

FIG. 3 shows an embodiment of the shaft unit with a bearing according to the present invention, and since the same reference numerals in FIG. 1 and FIG. 2 are the same components, the explanation thereof will be omitted.

1' hash shaft, this shaft 1' has grooves 1'a and 1'b for the ball receivers of the goal bearing, and a third 72-hole groove for the ball receiver in the middle of these grooves. It is equipped with 1'c. Reference numeral 9 denotes a flange having a groove 9a on its inner surface, and the third flange holds a bearing ball 10 at a position facing the groove 1'e. The outer diameter of this flange 9 is d, which is much smaller than that of the lower outer rings 2 and 3. 8□ and 8□ are coil central panels interposed between the upper outer ring 2 and the flange 9 and between the lower outer ring 3 and the flange 9.

The shaft unit with bearings configured in this way is fixed to the ball bearing support by press-fitting the lower outer ring, shrink fitting or adhesive means, and then simply fitting the upper outer ring to the ball bearing support. Support your body,
A case will be described in which the present invention is applied to a rotating body device in which the shaft receives a force in the upper thrust direction due to electromagnetic action, for example. In this case, a force in the upward direction (direction of arrow A) shown in FIG. 3 acts on the shaft 1'.

As a result, the upper outer ring 2 is displaced in the direction of the arrow, and in order to prevent the formation of a gap between the grooves 1'a and 28 for moving the bearing sole 4, the spring force of the coil spring 81 is applied. The coil spring 8 needs to be a dog as well. Therefore, the spring force of the coil spring 8 □ interposed between the flange 9 and the upper outer ring 2 is greater than that of the coil spring 82 interposed between the flange 9 and the lower outer ring 3. It must have spring force. Also,
Coil spring 8. When the spring forces of By making the pressure even stronger than the preload force applied to the lower outer ring 3, the upward direction (
Even when a force is applied in the direction of the arrow A), the pressure on the upper and lower bearing balls 4.5 can be maintained in a balanced state.

Furthermore, if a predetermined pressure is obtained against the lower bearing ball 5 due to the upward force acting on the shaft 1', the lower coil spring 8□ can be omitted.

Also, when a downward force acts on the shaft 1',
It will be easily understood that the preload force may be applied in the opposite manner to the above-mentioned method of applying the preload force.

Next, an example in which the shaft unit with a bearing of the present invention is applied to a rotating drum unit for a video tape recorder will be explained with reference to FIG.

Note that in FIG. 4, those designated by the same reference numerals in FIGS. 1 to 3 are the same constituent members, and therefore their explanations will be omitted.

In FIG. 4, the aforementioned shaft unit with bearings is attached to the stationary drum 11 in the same manner as shown in FIG.
It is attached to the central through hole 11b of.

In this case, since the outer diameter of the flange 9 is smaller than the outer diameters of the upper and lower outer rings 2 and 3, the outer circumference of the flange 9 is smaller than the inner circumference of the central through hole 11b of the fixed drum 11 as shown in the figure. It is in contact.

As already explained in FIG. 2, an upward force (in the direction of arrow A) is applied to the shaft 1' due to the magnetic attraction force generated between the rotating drum unit rotor magnet 16 and the stator coil 17. is applied, so the spring force of the upper coil spring 81 is transferred to the lower coil spring 82 so that the pressure applied to the upper and lower bearings 4 and 5 is balanced. Make it larger than the spring force, or coil springs 81 and 8.
．． If the spring force of the third ball bearing is the same, the flange 9 and the groove 1'e for the third ball receiver are provided at a position slightly biased toward the upper outer ring 2 side, so that the suspension pressure on the outer ring 2 is reduced from that on the outer ring 3. Make it bigger.

The manner in which the shaft unit is attached to the fixed drum 11 is as follows. That is, the lower outer ring 3 is completely attached to the lower bearing drum 11 by fixing means such as press fitting, shrink fitting, or adhesive, that is, the lower bearing H? - The upper outer ring 2 is simply fitted, and the upper bearing is fixed to the ring 4 in such a manner that the preload force cannot be adjusted. Attach to. And while the motor 16.17 is rotating, the four-tar magnet 1
When an upward force (in the direction of arrow A) is applied to the shaft 1' due to the magnetic attraction force generated between the stator coil 12 and the stator coil 12, this acting force is applied to the upper bearing pole 4. It acts in the direction of decreasing the pressure and acts in the direction of increasing the pressure applied to the lower bearing pole 4. However, since the coil spring 81 applies a much larger preload force to the upper outer ring 2 than the preload force applied to the lower outer ring 3, an upward force on the shaft 1' is applied. When you receive
As a result, the pressures on the upper and lower bearings and the poles 4 and 5 are balanced at appropriate values.

Contrary to the above case, the upper outer ring 2 is completely fixed to the fixed drum 1, that is, it is mounted on the fixed drum 1 in such a manner that no preload force is applied to the bearing pole 4, and the lower Simply fit the outer ring 3 onto the fixed drum 1 and remove the bearing.
When installed in such a way that the preload force can be adjusted for the motor 16, 17, the upper and lower bearing poles 4 and 5 will be The pressures balance at appropriate values.

In this way, in the rotating drum unit shown in FIG. 4, the shaft 1' is hardly shaken in the radial direction, and the accuracy in the height direction of the rotating magnetic head 13 during rotation is improved. can be fully guaranteed.

Incidentally, since the flange 9 is provided on the shaft 1' via the bearing sole 10, it does not pose any obstacle to the rotation of the shaft 1'.

Video of shaft unit with bearing of the present invention
Although an embodiment has been described in which it is applied to a rotating drum unit for a tape recorder, it goes without saying that the application is not limited to a rotating drum unit for a video tape recorder, and in particular, it is applicable to a rotating shaft in either of its thrust directions. It is most suitable for use in rotating devices where a force acting in one direction is applied.

(Effects) As detailed above, according to the present invention, in a shaft unit with a pole bearing provided with a plurality of outer ring members, a flange member is provided between the plurality of outer ring members, and a flange member is provided between the 7272 member and the outer ring member. By providing coil springs and varying the preload forces on the plurality of outer ring members, even if a force acts in one of the thrust directions of the shaft, the bearings 11? −
It is possible to maintain a balanced pressure on the valves.

[Brief explanation of drawings]

Figure 1 shows the conventionally proposed shaft with bearing.
Figure 2 is a cross-sectional view of the unit; Figure 2 is a cross-sectional view of an example in which the Shaft unit is applied to a rotating drum unit for a video tape recorder equipped with a face-to-face motor;
The figure is a sectional view of an embodiment of the shaft unit with a bearing of the present invention, and FIG. 4 is a sectional view of an example in which the shaft unit is applied to a rotating drum unit for a video tape recorder equipped with a surface-facing motor It is a diagram. 1'...Shaft, 1'a and l'b...Bearing and beer holder are in groove, 1'C...Third bearing and beer holder are in groove, 2 and 3.・・Outer ring member, 9・・
・Flange section, 41 s and 10...Bearing ball, 81...Spring member, 8. ...Second spring member.

Claims (5)

[Claims] (1) Each on both ends? -The bearing has a shaft with a concave groove, and a bearing in each concave groove on both ends.
a flange member rotatably attached to the shaft at an intermediate position between these concave front portions, and a space between the flange member and the first outer ring member. A shaft unit with a bearing, comprising a spring member interposed in the shaft unit. (2) The shaft has a third ball receiving groove part at an intermediate position between the two groove parts, and the flange member has a groove part for the third ball receiver.
J3's H? - A shaft unit with a bearing according to claim (1), wherein the ball receiver holds a bearing ball in a groove. (3) A second
A shaft unit with a bearing according to claim 1 or 2, comprising a spring member. (4) The flange part is arranged at a central position between the two outer ring members, and the spring force of the spring member arranged between the flange member and the first outer ring member is applied between the flange member and the second outer ring member. Claim (3) in which the spring force of the second spring part disposed between the outer ring member and the outer ring member is also reduced.
Shaft unit with bearing as described in section. (5) If the spring forces of both the spring members are approximately equal, the flange member and the center position between the two outer ring members will also be located slightly to the side of the first outer ring member. A shaft unit with a bearing according to claim (3).