JPS63269315A - Rotary drum device - Google Patents

Abstract

PURPOSE:To easily and inexpensively obtain a rotary drum device with a few amount of vibration and noise and durable for a long time usage and with a few amount of bearing loss, by forming a gas dynamic pressure bearing by providing a group on either the outer peripheral plane of the rotary shaft part of a rotary drum or the inner peripheral plane of the bearing part of a fixed drum. CONSTITUTION:A motor 12 is assembled in the rotary shaft part 13 of the rotary drum 16, and the rotary drum 16 is supported without being brought into contact with the fixed drum 11 by the gas dynamic pressure bearing provided between the outer peripheral plane of the rotary shaft part 13 and the inner peripheral plane of the bearing part 11a of the fixed drum 11. Since the motor 12 is assembled in the bearing part 13, circumferential speed is increased due to the increase of the area of the bearing, thereby, a large load capacity can be permitted. When the gas dynamic pressure bearing is applied, for example, the group is formed on the outer peripheral plane of the fixed bearing 1, and a rotary cylindrical shaft 2 is fitted in the outer peripheral side, and the motor 12 provided with a driving magnet 3, a driving coil 4, and an iron core 5 is arranged on the outer peripheral side of the cylindrical shaft 2. In such a way, it is possible to eliminate proper vibration, noise, or frictional fluctuation, to be durable for the long time usage, and also, to reduce liquid frictional loss due to the viscosity of lubricating oil, and to put no load on a power source device.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rotating drum device used in a tape recorder or the like, and particularly to a rotating drum device using a hydrodynamic bearing.

(Prior Art) In video tape recorders, digital audio recorders, etc., a rotating drum is provided in place of a fixed drum that guides the tape, and information signals are recorded on the tape by a magnetic head attached to the rotating drum. It is set to play.

The rotating drum is rotatably supported via bearings.

Conventionally, a ball bearing or a hydrodynamic bearing in which lubricating oil is interposed in a gap between a rotating shaft and the bearing has been used as this bearing.

(Problems to be Solved by the Invention) Conventional rotary drum bearings using ball bearings or hydrodynamic bearings using lubricating oil are not practical as rotary drum devices for general use.

However, when the rotation speed of the rotating drum reaches as high as 720 rpm, which is four times that of conventional video tape recorders, such as in high-quality video tape recorders for televisions, for example, conventional bearing mechanisms have various problems. will occur. That is, when a pole bearing is used as a bearing, the inherent noise and vibration become large, and the bearing cannot withstand long-term use. Further, when a dynamic pressure bearing with lubricating oil interposed therebetween is used, fluid friction loss due to the viscosity of the lubricating oil increases significantly, which places a burden on the power supply device.

In order to reduce such loss in bearings, it is necessary to reduce the bearing diameter or the bearing area. However, in high-quality video tape recorders, etc., the outer diameter and weight of the rotating drum are larger than conventional ones, so there is a limit to reducing the bearing diameter and bearing area, and the load on the bearing is This will further increase. Therefore, in order to cope with the problem with pole bearings and hydrodynamic bearings with lubricating oil, it is necessary to make full use of advanced technology from all aspects, such as improving accuracy, selecting materials, improving lubricating oil, and implementing various surface treatments. First, it is extremely difficult to achieve this goal by extending conventional technology.

The present invention has been made in view of such conventional problems, and by devising the structure of the bearing of the rotating drum, it is possible to withstand long-term use with less vibration and noise, and to reduce bearing loss. The purpose of the present invention is to easily and inexpensively provide a rotating drum device with a small number of units.

(Means for Solving the Problems) The present invention provides a rotating drum having a cylindrical rotating shaft at the center of rotation, and a rotating drum having a diameter larger than the rotating shaft and facing the outer circumferential surface of the rotating shaft. a fixed drum having a bearing part, and a motor for driving the rotating drum built into a cylindrical rotating shaft part of the rotating drum, the rotating drum having an outer circumferential surface of the rotating shaft part of the rotating drum or a bearing of the fixed drum. The gas dynamic pressure bearing is characterized in that a group is provided on either one of the inner circumferential surfaces of the portion to form a gas dynamic pressure bearing.

(effect) The rotating drum is rotationally driven by a motor.

The Tanabata is built into the cylindrical rotating shaft of the rotating drum, and is a gas dynamic pressure bearing provided between the outer circumferential surface of the rotating shaft and the inner circumferential surface of the bearing of the stationary drum that faces it. The rotating drum is supported without contact with the stationary drum. Since the motor is built into the bearing, the bearing area is increased, the circumferential speed is increased, and a large load capacity can be withstood.

(Example) Hereinafter, an example of a rotating drum device according to the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, a stationary drum designated by the reference numeral 11 has a bearing portion 11a having a cylindrical inner circumferential surface 11b. As is well known, the outer peripheral surface of the fixed drum 11 serves as a guide for a tape serving as an information signal recording medium.

A groove 11c is formed in the fixed drum 11 so as to go around the outside of the bearing portion 11a, and a stationary transformer 32 forming a part of the rotary transformer 35 is fixed to this groove 11c.

A cup-shaped frame 20 is fixed to the bottom of the fixed drum 11 with mounting screws 21. A column 22 is firmly planted in a hole in the center of the frame 20 by press fitting. The frame 20 has a cavity 2 extending around the hole in the center.
4 is formed, and a board 23 is attached so as to close this cavity 24 and on which electrical circuit components for driving a motor, which will be described later, are mounted and electrical wiring is carried out. The cavity 24 provides a space for wiring.

Above the fixed drum 11, a rotary drum 16 having an outer diameter substantially the same as that of the fixed drum 11 is rotatably supported by a support mechanism as described below. A hole is formed in the center of rotation of the rotating drum 16,
The protrusion of the rotating shaft portion 13 is fitted into this central hole. The rotating shaft portion 13 is formed into a cylindrical shape as a whole and has a shoulder portion 13a, and a rotating drum I6 is attached to the shoulder portion 13a.
The rotating shaft portion 13 is integrally attached to the rotating drum 16 by inserting a mounting screw 17 passing through the rotating drum 16.

The bearing portion 11a of the fixed drum 11 has a larger diameter than the rotating shaft portion 13 of the rotating drum 16, and the outer circumferential surface 13 of the rotating shaft portion 13
b is opposed to the outer circumferential surface 1 of the fixed drum 1 with a predetermined gap therebetween. A tapped hole is formed in the center of the rotating shaft portion 13, and a thrust receiving screw 29 is screwed into this screw hole, and this screw 29 protrudes from the lower surface side of the rotating shaft portion 13. On the other hand, a cup-shaped grease reservoir 27 is fixed to the upper end of the support column 22, and a thrust bearing 28 is fitted to the bottom of this grease reservoir 27. The thrust receiving screw 29 is dropped into the grease reservoir 27 and placed on the thrust bearing 28, so that the rotating shaft portion 13 and the rotating drum 16 are supported in the thrust direction. Inside the grease reservoir 27 is grease 38 for lubricating the thrust bearing.
is filled. The thrust bearing may be made of wear-resistant hard material, or may be grouped on the top surface to form a dynamic pressure bearing.

An annular magnet 31 is provided on the outer circumferential side of the grease reservoir 27.
is fixed thereto, and an annular magnet 30 is also fixed to the rotating shaft portion 13 side so as to surround the grease reservoir 27 . These magnets 30, 31 are arranged to face each other and are magnetized so that the opposing surfaces have the same polarity, and the repulsive force of the magnets 30, 31 causes the thrust formed by the thrust receiving screw 29 and the thrust bearing 28 to This prevents excessive load from being applied to the bearing.

Groups 36 are formed on the outer circumferential surface 13b of the rotating shaft portion 13, as shown in FIG.

The groups 36 are formed at both the upper and lower ends of the rotating shaft portion 13 at a predetermined angle with respect to the central axis, and the directions of the inclinations of the upper group and the lower group are reversed. Note that the group 36 may be formed on the inner peripheral surface 11b side of the fixed drum 11. In any case, the inner peripheral surface 13b of the rotating shaft portion 13 of the rotating drum 16 or the bearing portion 1 of the fixed drum 11
By providing the group 36 on at least one of the inner circumferential surfaces 11b of 1a, a gas dynamic pressure bearing is formed, and when the rotating drum 16 rotates, the rotating drum 16 is supported without contacting the fixed drum 11.

A magnetic head 9 is attached to the lower surface of the rotary drum 16 near the outer periphery using attachment screws 18 . Further, a rotating side transformer 33, which constitutes a part of a rotating transformer 35, is attached to the lower surface side of the rotating drum 16 by a suitable mounting member. The rotating transformer 33 is located within the groove 11c of the fixed drum 11 and faces the fixed transformer 32.

A motor 1 for driving the rotary drum 16 is provided on the outer circumference of the support column 22 and on the inner circumference of the rotation shaft portion 13 of the rotary drum 16.
2 is placed. The motor 12 includes an iron core 25 for forming a magnetic path fixed to the outer periphery of the support column 22, and this iron core 2.
5 and the rotating shaft portion 1 of the rotating drum 16.
A cylindrical magnet 15 is fixed to the inner peripheral surface of the magnet 3 via a cylindrical yoke 14. The structure of the motor 12 itself is the same as a well-known one, and the magnet 5 is energized by controlling the winding 26 to be energized through a drive circuit and a control circuit formed on the substrate 23, and thereby the rotating drum 16 is energized. is rotated at a predetermined speed. Note that the yoke 14 does not necessarily need to be provided.

On the upper surface of the rotating drum 16, there is a Guinamik balun. ”
Hizuki and Nibakuon Publishing are included. The combination of d and t is -.

According to the embodiment described above, the motor 12 for driving the rotating drum is disposed inside the rotating shaft portion 13 of the rotating drum 16,
Since the outer circumferential surface 13b of the rotating shaft section 13 is fitted and supported on the inner circumferential surface 11b side of the bearing section 11a of the fixed drum 11, the outer diameter and bearing area of the rotating shaft section 13 are considerably large. Therefore, due to the synergistic effect of increasing the circumferential speed of the bearing and increasing the bearing area, a large load capacity can be obtained. It is also applicable to a rotating drum device with a large capacity. In addition, in general, rotating drum devices, when rotating at high speeds such as 7000 rpm, have: 1) less rotational unevenness, 2) less lateral runout, 2) good axial head position accuracy and less runout, and 2) long life. (1) The amount of power consumption during startup and rotational driving is small. However, according to the embodiment of the rotating drum device according to the present invention, the rotation m of the rotating drum 16 is low. A motor 12 for driving two rotatable drums is arranged inside, and the outer circumferential surface 13b of the rotating shaft section 13 is connected to the inner circumferential surface 11 of the bearing section 11a of the fixed drum 11.
Since it is fitted and supported on the b side, all of these requirements can be met.

Note that FIGS. 3 and 4 show examples of possible structures when applying a gas dynamic pressure bearing to a rotating device. Third
In the example shown in the figure, a group is formed on the outer circumferential surface of the fixed shaft stack, a rotating cylindrical shaft 2 is fitted on the outer circumferential side of the group, and a driving magnet 3, a driving coil 4, and an iron core 5 are installed on the outer peripheral side of this cylindrical shaft 2. This is the arrangement in which the motors are arranged. Reference numeral 6 is a thrust bearing. In the example shown in FIG. 4, a group is formed on the outer circumferential surface of a rotating shaft 1, a fixed cylindrical shaft 2 is fitted on the outer circumferential side, a shaft 1a is made to protrude from the lower end of the rotating shaft l, and a drive magnet is attached to this shaft la. 3 is fitted, and a driving coil 4 and an iron core 5 are arranged around its outer periphery. Reference numeral 6 is a thrust bearing.

The inside of the fixed bearing 1 in the one shown in Figure 3 or the rotating shaft 1 in the one shown in Figure 4 becomes a dead space that is not used for anything, and making this part thicker (doing so will only take up unnecessary space and make the device larger). Therefore, devices subject to certain dimensional restrictions cannot have a very large diameter and cannot obtain sufficient load capacity.

In this regard, according to the embodiment of the rotating drum device according to the present invention, while effectively utilizing the inside of the cylindrical rotating shaft portion 13 of the rotating drum 16 as the rotating drum driving motor 12, the outer diameter of the rotating shaft portion 13 is Since this can be made sufficiently large, it is possible to ensure sufficient load capacity while effectively utilizing space and downsizing.

In FIG. 1 and FIG. 2, the rotating shaft portion 13, the rotating tram 1
6. The fixed drum 11, frame 20, etc. can be made by the same method as used in ordinary drum units. For example, it can be manufactured using aluminum alloy and mainly by forging, turning, etc.

Shoulder portion 13a of rotating shaft portion 13 to which rotating drum 16 is attached
can be turned in the same chucking state as when machining the outer circumferential surface 13b of the rotating shaft portion 13, so the shoulder portion 1
The accuracy of the perpendicularity between 3a and the outer peripheral surface 13b is good, and therefore,
This has the effect that the axial deflection of the peripheral edge of the rotary drum 16, which is related to the mounting accuracy of the rotary drum 16, is extremely reduced.

After forming a group by etching or the like on at least one of the outer circumferential surface 13b of the rotating shaft section 13 or the inner circumferential surface 11b of the fixed drum 1, the rotating shaft section is 13 outer peripheral surface 13b
The inner circumferential surface 11b of the fixed drum 11 may be plated with electroless nickel or hard alumite. Furthermore, in the case of alumite, the surface pores are impregnated with a lubricant, and even in the case of plating, fluororesin-based lubricants and other commonly used lubricants are used. flJ? You may apply a thin layer of h-san. In this way, one of the outer circumferential surface 13b of the rotating shaft portion 13 and the inner circumferential surface 11b of the stationary drum 11 is subjected to a wear-resistant surface treatment, and the other is subjected to a wear-resistant and lubricating surface treatment. Therefore, the sliding friction and wear during starting and stopping can be kept to an extremely low level, and it can sufficiently withstand several hundred thousand starting and stopping operations. Furthermore, since the radial bearing is non-contact during steady rotation, it can withstand long-term use.

Most of the load in the thrust direction of the rotating part is carried by magnet 3.
Since it is supported by a repulsion force of 0.31, the load applied between the thrust receiving screw 29 and the thrust bearing 28 is extremely small, and combined with the effect of the lubricating grease 38, the wear of the contact portion can be extremely reduced. . In the illustrated example, the tip of the thrust receiving screw 29 is a spherical surface with an appropriate curvature, but when forming a group for a hydrodynamic bearing, the tip of the screw 29 is flat and perpendicular to the axial direction. Finish. The magnets 30.3 for reducing the load in the thrust direction are not essential to the present invention, and especially when the thrust bearing portion is a dynamic pressure bearing as described above, it is not necessary to provide the magnets 30.31.

The axial position of the magnetic head 19 is determined by the thrust receiving screw 1.
9 allows adjustment to the optimum position.

By putting adhesive into the groove 16a formed in the rotating drum 16 and adjusting the balance of the rotating part, the lateral runout of the shaft can be suppressed to 1 μm or less. The outer circumferential surface 13b of the rotating shaft part work 3 and the outer circumferential surface 11 of the fixed drum 11
The gap with b should be 4 to 10 μm on one side.

(Effects of the Invention) According to the present invention, a motor for driving the rotating drum is disposed inside the rotating shaft portion of the rotating drum, and the outer peripheral surface of the rotating shaft portion is fitted onto the inner peripheral surface side of the bearing portion of the fixed drum. Since the rotary shaft is supported by a rotary shaft, the outer diameter and bearing area of the rotating shaft portion are considerably large. Therefore, due to the synergistic effect of increasing the circumferential speed of the bearing and increasing the bearing area, a large load capacity can be obtained. It is also applicable to large rotating drum devices. In addition, since the present invention uses a gas dynamic pressure bearing, there is no inherent movement, noise, or friction fluctuation that is seen in conventional ball bearings, and it can withstand long-term use. There is no fluid friction loss due to the viscosity of the lubricating oil, which occurs when dynamic pressure bearings are used with lubricating oil, and there is no burden on the power supply device.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a rotating drum device according to the present invention, FIG. 2 is a partially sectional front view showing the rotating shaft portion and fixed drum in the same embodiment, and FIG. 3 is a general FIG. 4 is a longitudinal cross-sectional view showing an example of a possible dynamic pressure bearing. FIG. 4 is a vertical cross-sectional view showing another example of a generally possible dynamic pressure bearing. 11...Fixed drum, lla...Bearing part, ll
b...Inner circumferential surface of bearing part, 12...Motor, 13...Rotating shaft part, 13b...Inner circumferential surface of rotating shaft part, 16...
Rotating drum, 19... Axis head, 32... Fixed side transformer, 33... Rotating side transformer, 36... Group. (Hano) 16) 4th place

Claims (1)

[Scope of Claims] A rotating drum having a magnetic head and a rotating transformer, and having a cylindrical rotating shaft at the center of rotation, and having approximately the same diameter as the rotating drum and facing the rotating transformer. a fixed drum having a fixed side transformer at a position where the rotary drum rotates, and a fixed drum having a bearing portion having a diameter larger than the rotating shaft portion of the rotating drum and facing an outer peripheral surface of the rotating shaft portion; and a motor for driving a rotating drum built into the shaft, and a group is provided on either the outer circumferential surface of the rotating shaft of the rotating drum or the inner circumferential surface of the bearing section of the fixed drum to provide a gas dynamic pressure bearing. A rotating drum device formed by