JPH05298635A - Rotary cylinder device and its manufacture - Google Patents

Abstract

PURPOSE:To obtain the rotary cylinder device which has superior recording and reproduction characteristics and can be manufactured at low cost by reducing the outward shape size of a rotary cylinder and improving the precision of the fitting of a magnetic head core to a rotary shaft. CONSTITUTION:The rotary cylinder of the rotary cylinder device is divided into two components which are an inside rotary cylinder 1 and an outside rotary cylinder 2; and a magnetic head core 3 which is stuck directly on the inside rotary cylinder 1 without using a head base which is conventionally used and a flange member 6 which is coupled with the rotary shaft 4 is fitted in a reference hole 1a formed in the inside rotary cylinder 1. Further, the positioning of the magnetic head core 3, the final polishing of the slide surface 3a of the magnetic head core, and the fitting of the rotary shaft 4 and inside rotary cylinder 1 are based upon the reference hole 1a formed in the inside rotary cylinder 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary cylinder device used in a magnetic recording / reproducing apparatus such as a video tape recorder (hereinafter referred to as VTR) for recording / reproducing signals and information, and an audio tape recorder, and its manufacture. Regarding the method.

[0002]

2. Description of the Related Art FIG. 15 is a sectional view of a rotary cylinder device disclosed in, for example, Japanese Patent Publication No. 2-257415. In the figure,
Reference numeral 20 denotes a ring-shaped head base, and the magnetic head core 3 is fixed to a head mounting portion 20a provided on the head base 20 by a method such as bonding. The head base 20 is fixed to the rotary cylinder 21 by a method such as screwing so that the tip of the magnetic head core 3 projects beyond the outer peripheral surface 21a of the rotary cylinder 21. Further, a cutout 21b is formed on the outer peripheral surface 21a of the rotary cylinder 21, and the magnetic head core 3 is placed in the cutout 21b so that the magnetic head core 3 and the rotary cylinder 21 do not come into direct contact with each other.

The rotary cylinder 21 is attached to the flange member 6, and the rotary portion of the rotary shaft 4 and the bearing member 5 is connected to the flange member 6. The fixed part of the bearing member 5 is
It is fixed to the fixed cylinder portion 7. A rotary transformer 8 is fixed to the rotary cylinder 21 or the flange member 6, and a rotary transformer 8 is fixed to the fixed cylinder portion 7. Further, a motor is attached to the other end of the rotary shaft 4 on the side where the rotary cylinder 21 is not attached.

Next, the operation will be described. When the motor 9 rotates at a constant speed, the rotary cylinder 21 and the magnetic head core 3 connected to the rotary shaft 4 rotate. In this state, the magnetic tape 11 is brought into contact with the magnetic head core 3, and a signal is transferred to and from the magnetic head core 3 via the rotary transformer 8 to record / reproduce the signal on / from the magnetic tape 11.

Next, the manufacturing method will be described. The magnetic head core 3 is fixed to the head mounting portion 20a of the head base 20 by a method such as bonding. At this time, the relative positioning between the magnetic head core 3 and the head base 20 is performed. Next, the head base 20 is attached to the polishing rotary jig 12, and further,
After fixing the polishing rotary jig 12 to the polishing rotary shaft 13, the polishing tape is brought into contact with the magnetic head core 3 and the polishing rotary jig 12 while the rotary rotary shaft 13 is rotated to perform polishing. The shape of the sliding surface of the magnetic head core 3 is formed.

Next, as shown in FIG. 14, the vicinity of the gap of the magnetic head core sliding surface 3a is the outer peripheral surface 21a of the rotary cylinder 21.
More than specified size, and the rotary cylinder 21
After positioning the head base 20 so that the posture of the head base 20 is within the specified range,
And the rotary cylinder 21 are fixed by a method such as screwing.

On the other hand, in another process, the rotary transformer 8 is fixed to the flange member 6, the rotary transformer 8 is fixed to the fixed cylinder portion 7, and then the rotary portions of the rotary shaft 4 and the bearing member 5 are fixed to the flange member 6. Then, the fixed portion of the bearing member 5 and the fixed cylinder portion 7 are fixed. Further, a motor is attached to the other end of the rotary shaft 4 on the side where the rotary cylinder 21 is not attached.

Next, the rotary cylinder 21 is fixed to the flange member 6 after performing positioning adjustment so that the deflection of the outer peripheral surface 21a of the rotary cylinder 21 with respect to the rotary shaft 4 is within a specified value.

[0009]

Since the conventional rotary cylinder device is constructed as described above, the head base 20, the rotary cylinder 21, and the flange member 6 are interposed between the magnetic head core 3 and the rotary shaft 4. However, the mounting position error between these components deteriorates the relative position accuracy of the magnetic head core 3 with respect to the rotating shaft 4. This causes the following problems in the magnetic recording / reproducing apparatus using the rotating cylinder device. One is that the rotation of the magnetic head core 3 causes a precession movement, which deteriorates the dimensional accuracy of the magnetization pattern recorded on the magnetic tape 11, and the other is that the magnetic head core 3 projects from the rotating cylinder 21. An error in the amount causes the contact state between the magnetic head core 3 and the magnetic tape 11 to become unstable, resulting in increased spacing loss and deterioration in the characteristics of the recording / reproducing output, particularly in the short wavelength region.

Further, since the tip shape of the magnetic head core 3 is formed on the basis of the polishing rotary shaft 13, the optimum tip with respect to the center of rotation due to a processing error or an installation error in the state of being attached to the rotary cylinder 21. The shape deviates from the shape. For this reason, the contact state between the magnetic head core 3 and the magnetic tape 11 becomes unstable and the spacing loss increases, which further deteriorates the characteristics of the recording / reproducing output, particularly in the short wavelength region.

Further, since the number of parts interposed between the magnetic head core 3 and the rotary shaft 4 increases, there has been a problem in downsizing the rotary cylinder device. In particular, there has been a big problem in reducing the diameter of the rotary cylinder 21.

Further, although the magnetic head core 3 is fixed after the positioning with respect to the head base 20, the positioning adjustment needs to be performed again with high accuracy when the head base 20 is attached to the rotary cylinder 21. However, there is also a problem that the cost required for assembly increases.

The present invention has been made in order to solve the above-mentioned problems, and achieves high mounting accuracy of a magnetic head core and excellent recording / reproducing characteristics, and also reduces the external dimensions of the entire rotary cylinder device. An object of the present invention is to obtain a rotary cylinder device that can be manufactured at low cost, and further to provide a manufacturing method suitable for this rotary cylinder device.

[0014]

In a rotary cylinder device according to the present invention, a magnetic head core is fixed near the outer circumference of an inner rotary cylinder, and an outer rotary cylinder is fitted and fixed to the outer peripheral surface of the inner rotary cylinder. Is. Also,
The tip of the magnetic head core is in a positional relationship of protruding from the outer peripheral surface of the outer rotary cylinder.

Further, a notch is provided in the outer peripheral portion of the outer rotary cylinder, and the tip of the magnetic head core is arranged at a position protruding from the outer peripheral surface of the outer rotary cylinder through the notch.

Further, the front surface of the outer rotary cylinder facing the fixed cylinder portion is located farther from the fixed cylinder portion than the surface of the inner rotary cylinder facing the fixed cylinder portion, so that the tip of the magnetic head core is rotated outward. It is arranged at a position projecting from the outer peripheral surface of the cylinder.

The reference hole of the inner rotary cylinder is directly fitted to the bearing member or the rotary shaft to fix the inner rotary cylinder to the bearing member or the rotary shaft.

Further, the inner rotary cylinder and the flange member are fixed by fitting the reference hole of the inner rotary cylinder and the flange member, and the flange member and the bearing member or the rotary shaft are fixed.

Further, a fluid bearing is formed by the reference hole of the inner rotary cylinder and a fixed shaft fixed to the fixed cylinder portion so that the rotary cylinder portion and the fixed cylinder portion are combined.

In the method of manufacturing the rotary cylinder device, positioning is performed with reference to a reference hole provided in the inner rotary cylinder, and then one or more magnetic head cores are provided near the outer circumference of the inner rotary cylinder. The inner rotary cylinder and the polishing rotary shaft at the position where the center of the reference hole and the center of the polishing rotary shaft are aligned with each other by fixing them to the magnetic head core by a method such as bonding. A second step of fixing and rotating the polishing rotary shaft, forming a curved surface shape of the sliding surface of the magnetic head core with the polishing tape, and removing the polishing rotary shaft from the inner rotary cylinder;
A third step of fixing the inner rotary cylinder and the outer rotary cylinder, and a fourth step of fixing and fixing the inner rotary cylinder and the rotary shaft at a position where the center of the reference hole of the inner rotary cylinder coincides with the rotation center of the rotary shaft. It is manufactured through the process.

In the second step, after the cylindrical polishing jig is fixed to the outer peripheral surface of the inner rotary cylinder, the polishing tape is rotated while the polishing rotary shaft is rotated. The curved surface shape of the sliding surface of the magnetic head core is formed by contacting and polishing the tool and the magnetic head core.

In the second step, the curved surface of the sliding surface of the magnetic head core is formed by using a polishing rotary jig having an outer peripheral surface with a radius of curvature smaller than that of the outer peripheral surface of the outer rotating cylinder. To form.

In the second step, the curved surface shape of the sliding surface of the magnetic head core is formed by bringing the polishing tape into contact with the inner rotary cylinder and the magnetic head core and polishing the same.

[0024]

The rotary cylinder device constructed as described above is
Since the magnetic head core is attached with high accuracy to the center of rotation of the rotating shaft and the deviation of the scanning trajectory of the magnetic head core during rotation is small in both the radial and thrust directions, the dimensional accuracy of the magnetization pattern recorded on the magnetic tape Is improved,
Further, the contact pressure between the magnetic head core and the magnetic tape becomes stable in the rotation phase direction, and the characteristics of the recording / reproducing output, especially in the short wavelength region, become stable.

Further, since the tip shape of the magnetic head core is the optimum tip shape with respect to the center of rotation, the contact state between the magnetic head core and the magnetic tape is stabilized, spacing loss is reduced, and recording / reproduction output is particularly short wavelength. The characteristics of the area become more stable.

[0026]

【Example】

Example 1. FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, the magnetic head core 3 is fixed by a method such as adhesion to the vicinity of the outer peripheral surface on one side of the surface perpendicular to the outer peripheral surface 1b of the inner rotary cylinder 1. Inner rotating cylinder 1
The inner peripheral surface 2a of the outer rotary cylinder 2 is fitted and fixed to the outer peripheral surface 1b, and the outer rotary cylinder 2 and the inner rotary cylinder 1 are fixed by press fitting or adhesion. Further, as shown in FIG. 2, the outer peripheral surface 2b of the outer rotary cylinder 2 is
A cutout 2c is formed in the cutout 2c, and the magnetic head core 3 is formed in the cutout 2c.
, And the tip sliding surface 3a of the magnetic head core projects more than the outer peripheral surface 2b of the outer rotary cylinder 2 through the notch 2c. A reference hole 1a is provided in the center of the inner rotary cylinder 1.
The reference hole 1a is fitted into the flange member 6 so that the inner rotary cylinder 1 and the flange member 6 are fixed. Since the relationship between the flange member 6 and the fixed cylinder portion 7 is the same as the configuration of the conventional example, description thereof will be omitted.

The operation of recording / reproducing a signal to / from the magnetic head core 3 on the magnetic tape 11 in the rotary cylinder device constructed as described above is the same as the conventional one, and therefore its explanation is omitted. The operational characteristic of the rotary cylinder device according to the present invention is that the rotational accuracy of the magnetic head core 3 is improved. That is, the magnetic head core 3 does not use the conventionally used head base 20 but the reference hole 1a on the inner rotary cylinder 1.
Since the magnetic head core 3 is directly fixed to the position with respect to the rotational axis, the positional accuracy of the magnetic head core 3 with respect to the rotation center of the rotating shaft is improved, and the deviation of the scanning locus of the magnetic head core 3 during rotation is small in both the radial direction and the thrust direction. For magnetic tape
The dimensional accuracy of the magnetization pattern recorded on 11 is improved, and the contact pressure between the magnetic head core 3 and the magnetic tape 11 is stabilized in the rotational phase direction, and the characteristics of the recording / reproducing output, particularly in the short wavelength region, are stabilized.

The shape of the sliding surface 3a at the tip of the magnetic head core is formed on the basis of the center of rotation of the rotary shaft, so that it is the optimum shape for the magnetic tape 11, and the magnetic head core 3 and the magnetic tape 11 have the same shape. The contact state becomes stable, spacing loss is reduced, and the characteristics of the recording / reproducing output, particularly in the short wavelength region, are further stabilized.

The manufacturing method of the rotary cylinder device is as follows: (a) First step (see FIGS. 3 (a) and 3 (b)): Positioning is performed with reference to the reference hole 1a provided in the inner rotary cylinder 1. After that, the step of fixing the magnetic head core 3 to the vicinity of the outer periphery of the inner rotating cylinder by a method such as bonding and winding the coil around the magnetic head core, (b) the second step (see FIGS. 4 (a) and 4 (b)) ): The inner rotary cylinder 1 and the polishing rotary shaft 13 are located at a position where the center of the reference hole 1a of the inner rotary cylinder 1 and the center of the polishing rotary shaft 13 are aligned with each other.
After further fixing the cylindrical rotary jig 14 having a cylindrical shape with a radius of curvature of the outer peripheral surface being smaller than the radius of curvature of the outer peripheral surface 2b of the outer rotary cylinder to the outer peripheral surface 1b of the inner rotary cylinder, the polishing rotary With the shaft 13 rotated, the polishing tape 15
Is brought into contact with the polishing rotary jig 14 and the magnetic head core 3 to perform polishing to form a curved surface shape of the sliding surface 3a of the magnetic head core, and from the inner rotary cylinder 1 to the polishing rotary jig 14 and the polishing rotary shaft 13. After removing the magnetic head core 3, the magnetic tape 11 is brought into contact with the magnetic tape 11 to perform recording / reproducing or to conduct electrical conduction to inspect the characteristics of the magnetic head core, and (c) the third step (see FIG. a) to (b)): A step of fixing the inner rotary cylinder 1 and the outer rotary cylinder 2 by fitting the outer peripheral surface 1b of the inner rotary cylinder and the inner peripheral surface 2a of the outer rotary cylinder, and (d) the fourth step. (Refer to FIG. 6): The step of attaching and fixing the inner rotary cylinder 1 and the flange member 6 at a position where the center of the reference hole 1a of the inner rotary cylinder coincides with the center of rotation of the rotary shaft 4.

Example 2. In the first embodiment, the notch 2c is provided in order to project the tip end portion 3a of the magnetic head core from the outer peripheral surface 2b of the outer rotary cylinder, but as shown in FIGS. 7 and 8, the fixed cylinder portion of the outer rotary cylinder 2 is provided. Side facing surface
2d is the facing surface 1c of the inner rotary cylinder 1 on the fixed cylinder side.
Instead of this, the positional relationship may be such that it is separated from the fixed cylinder portion 7 over the entire circumference. With this configuration, it is not necessary to provide the notch 2c on the outer peripheral surface 2b of the outer rotary cylinder, and the machining cost of the outer rotary cylinder 2 can be reduced.

The method of manufacturing the above rotary cylinder device is the same as the method of the first embodiment.

Example 3. In the first embodiment, the inner rotary cylinder 1 and the rotary shaft 4 are connected via the flange member 6, but the rotary shaft 4 is directly fitted into the reference hole 1a of the inner rotary cylinder as shown in FIG. You may. In this example, the rotating shaft 4 and the rotating portion of the bearing member 5 are coupled, and the bearing member 5 uses a ball bearing.

Example 4. Further, as shown in FIG. 10, a fluid bearing may be used for the bearing member 5. In this case, the fluid bearing is of a type in which the rotary shaft 4 rotates integrally with the inner rotary cylinder 1.

In the configurations shown in the third and fourth embodiments, the flange member 6 is not required, so that the outer dimensions of the rotary cylinder device can be made small and the number of parts can be reduced, so that the cost can be reduced.

The method of manufacturing the rotary cylinder device according to the third and fourth embodiments is the same as the method according to the first embodiment.

Example 5. As a modification of the bearing member 5 using the fluid bearing shown in FIG. 10 of the third embodiment, a fluid bearing with a fixed shaft 16 as shown in FIG. 11 may be used.
In this case, the reference hole 1a of the inner rotary cylinder also functions as the rotary side receiving surface of the fluid bearing.

With the above construction, the connecting portion between the inner rotary cylinder 1 and the rotary shaft 4 can be omitted, so that the widthwise dimension of the magnetic tape 11 of the rotary cylinder device can be reduced.

The manufacturing method of the rotary cylinder device described above is carried out except that the inner rotary cylinder 1 and the fixed shaft 16 are mounted at the position where the center of the reference hole 1a of the inner rotary cylinder coincides with the center of the fixed shaft 16 in the fourth step. The method is the same as in Example 1.

Example 6. In the embodiment shown in FIG. 12, a right-angled flange portion 2e is provided on the inner peripheral surface 2a of the outer rotary cylinder. With this construction, the magnetic tape 11 for fixing the outer rotary cylinder 2 and the inner rotary cylinder 1 is fixed. Positioning in the width direction is easy and the position accuracy is improved. Also,
It is also possible to use the flange portion 2e for screwing.

The manufacturing method of the above rotary cylinder device is the same as the method of the first embodiment.

Example 7. As shown in FIG. 1, the rotary transformer 8 or the recording / reproducing signal processing circuit 17 may be attached to the inner rotary cylinder 1. With this configuration, the S / N ratio of the recording / reproducing signal can be improved, and the size of the entire rotary cylinder device can be reduced.

Example 8. In the second step of the manufacturing method of the above-described embodiment, the polishing rotary jig 14 is used, but without using this, the polishing tape is brought into contact with the inner rotary cylinder 1 and the magnetic head core 3 to perform polishing. As shown in FIG. 13, a method of forming the curved surface shape of the sliding surface 3a of the magnetic head core may be used. With this manufacturing method, the polishing rotary jig 14
The manufacturing cost is reduced because the steps of attaching to and removing from the inner rotary cylinder 1 can be omitted.

The shape of the sliding surface 3a of the magnetic head core is different from that of the manufacturing method of the above embodiment. The advantage of this manufacturing method is that the polishing tape can be largely deformed as compared with the manufacturing method of the above-described embodiment, so that the radius of curvature of the tip R shape of the sliding surface 3a of the magnetic head core can be formed small. .. This is an effective means for forming the optimum R shape of the sliding surface 3a of the magnetic head core with respect to the magnetic tape 11 when the outer diameter of the rotary cylinder device is reduced. The contact state becomes stable, spacing loss is reduced, and the characteristics of the recording / reproducing output, particularly in the short wavelength region, are improved.

[0044]

Since the present invention is constructed as described above, it has the following effects.

By reducing the number of parts interposed between the magnetic head core and the rotary shaft, the parts cost can be reduced and the rotary cylinder device can be downsized. In particular, it is effective in reducing the diameter of the rotary cylinder.

Further, the magnetic head core is fixed near the outer circumference of the inner rotary cylinder with reference to the reference hole of the rotary cylinder, and the outer rotary cylinder is fitted and fixed on the outer peripheral surface of the inner rotary cylinder. Since the reference hole of the rotating cylinder and the center of the rotating shaft are aligned, the magnetic head core is mounted with high accuracy with respect to the rotating center of the rotating shaft, and the magnetic head core scans during rotation. Since the deviation of the trajectory is small both in the radial direction and the thrust direction, the dimensional accuracy of the magnetization pattern recorded on the magnetic tape is improved, and the contact pressure between the magnetic head core and the magnetic tape becomes stable, and the recording / reproducing output is particularly short wavelength. The characteristics of the area are stable.

Further, since the sliding surface shape of the magnetic head core is formed by polishing using the reference hole as a reference, it has an optimum shape for the center of rotation. Therefore, the contact state between the magnetic head core and the magnetic tape becomes stable, the spacing loss is reduced, and the characteristics of the recording / reproducing output, particularly in the short wavelength region, are further stabilized.

Further, after fixing the magnetic head core to the inner rotary cylinder, it is not necessary to adjust the positioning of the magnetic head core, so that the cost required for assembly is reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing a notch of the outer rotation cylinder of Embodiment 1 of the present invention.

FIG. 3 is a first process diagram of a method for manufacturing a rotary cylinder device according to the first embodiment of the present invention.

FIG. 4 is a second process diagram of the method for manufacturing the rotary cylinder device according to the first embodiment of the present invention.

FIG. 5 is a third process diagram of the method for manufacturing the rotary cylinder device according to the first embodiment of the present invention.

FIG. 6 is a fourth process chart of the method for manufacturing the rotary cylinder device according to the first embodiment of the present invention.

FIG. 7 is a perspective view showing an outer rotating cylinder in Embodiment 2 of the present invention.

FIG. 8 is a sectional view showing a second embodiment of the present invention.

FIG. 9 is a sectional view showing a third embodiment of the present invention.

FIG. 10 is a sectional view showing Embodiment 4 of the present invention.

FIG. 11 is a sectional view showing Embodiment 5 of the present invention.

FIG. 12 is a sectional view showing Embodiment 6 of the present invention.

FIG. 13 is a manufacturing process drawing of an eighth embodiment of the present invention.

FIG. 14 is a perspective view showing a method of assembling a rotary cylinder of a conventional rotary cylinder device.

FIG. 15 is a cross-sectional view showing a conventional rotary cylinder device.

[Explanation of symbols]

 1 inner rotary cylinder 2 outer rotary cylinder 3 magnetic head core 4 rotary shaft 5 bearing member 6 flange member 7 fixed cylinder part 8 rotary transformer 13 polishing rotary shaft 14 polishing rotary jig 15 polishing tape 16 fixed shaft 17 recording / reproducing signal processing circuit

Claims (12)

[Claims] 1. A rotary cylinder device of a magnetic recording / reproducing apparatus in which a rotary cylinder part and a fixed cylinder part form a pair, and at least a part of an outer peripheral surface of an inner rotary cylinder and at least a part of an inner peripheral surface of an outer rotary cylinder. The inner rotary cylinder and the outer rotary cylinder are fixed together to form a rotary cylinder part, and the inner rotary cylinder is positioned at a position where the tip of the magnetic head core projects beyond the outer peripheral surface of the outer rotary cylinder. A rotary cylinder device, wherein one or more magnetic head cores are arranged in the vicinity of the outer circumference of the cylinder. 2. An outer peripheral portion of the outer rotary cylinder is provided with one or a plurality of notches, and the tip of the magnetic head core is disposed at a position protruding from the outer peripheral surface of the outer rotary cylinder. The rotary cylinder device according to claim 1. 3. The magnetic head core of the magnetic head core is configured such that the facing surface of the outer rotary cylinder facing the fixed cylinder portion is located farther from the fixed cylinder portion than the facing surface of the inner rotary cylinder facing the fixed cylinder portion. The rotary cylinder device according to claim 1, wherein the tip is arranged at a position projecting from the outer peripheral surface of the outer rotary cylinder. 4. A reference hole is provided in the inner rotary cylinder,
2. The rotary cylinder according to claim 1, wherein the reference hole and the flange member are fitted to each other to couple the inner rotary cylinder and the flange member, and the flange member and the bearing member or the rotary shaft are connected to each other. apparatus. 5. A reference hole is provided in the inner rotary cylinder,
2. The rotary cylinder device according to claim 1, wherein the reference hole and the bearing member or the rotary shaft are directly fitted to couple the inner rotary cylinder with the bearing member or the rotary shaft. 6. A reference hole is provided in the inner rotary cylinder,
2. The rotary cylinder device according to claim 1, wherein a fluid bearing is formed by the reference hole and a fixed shaft fixed to the fixed cylinder portion to connect the rotary cylinder portion and the fixed cylinder portion. 7. A rotary transformer is provided in the inner rotary cylinder,
Alternatively, the rotary cylinder device according to claim 1, further comprising a recording / reproducing signal processing circuit. 8. After positioning with reference to a reference hole provided in the inner rotary cylinder, one or a plurality of magnetic head cores are fixed near the outer periphery of the inner rotary cylinder by a method such as adhesion, The first step of winding the coil on the magnetic head core, and fixing the inner rotary cylinder and the polishing rotary shaft at a position where the center of the reference hole and the center of the polishing rotary shaft are aligned, and the polishing rotation is performed. A second step of removing the polishing rotary shaft from the inner rotary cylinder after forming a curved surface shape of the sliding surface of the magnetic head core with the polishing tape in a state where the shaft is rotated, and an outer periphery of the inner rotary cylinder. A third step of fixing the inner rotary cylinder and the outer rotary cylinder by fitting the surface and the inner peripheral surface of the outer rotary cylinder, and aligning the center of the reference hole of the inner rotary cylinder with the center of rotation of the rotary shaft. In the position A method for manufacturing a rotary cylinder device, which is manufactured through a fourth step of mounting and fixing a side rotary cylinder and the rotary shaft. 9. In the second step, a cylindrical polishing jig is fixed to the outer peripheral surface of the inner rotating cylinder, and then a polishing tape is brought into contact with the polishing jig and the magnetic head core. 9. The method of manufacturing a rotary cylinder device according to claim 8, wherein after the curved surface shape of the sliding surface of the magnetic head core is formed by polishing, the polishing rotary jig is removed from the inner rotary cylinder. 10. The curved shape of the sliding surface of the magnetic head core is formed in the second step by contacting and polishing an abrasive tape with the inner rotary cylinder and the magnetic head core. Item 8. A method for manufacturing a rotary cylinder device according to item 8. 11. In the second step, after the curved surface shape of the sliding surface of the magnetic head core is formed, a magnetic tape is brought into contact with the magnetic head core to perform recording / reproduction, or electrical conduction is performed. 9. The method for manufacturing a rotary cylinder device according to claim 8, wherein the characteristics of the magnetic head core are inspected by. 12. A curved surface shape of a sliding surface of a magnetic head core is used in the second step, which uses a polishing jig whose outer peripheral surface has a radius of curvature smaller than that of an outer peripheral surface of an outer rotating cylinder. 10. The method for manufacturing a rotary cylinder device according to claim 9, wherein: