JP2510885B2 - Machining method of rotating magnetic head cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for machining a fixed cylinder used in a rotary magnetic head cylinder of a helical scan type.

<Prior Art> A helical scan type rotary magnetic head cylinder E used in a magnetic recording / reproducing apparatus has, as shown in FIGS. 5 to 7, a rotary cylinder 50 concentric with a fixed cylinder 20 in an axial direction. Are combined in a shape. A total of four magnetic heads 60 are incorporated at the lower end of the rotary cylinder 50.
When the rotating cylinder 50 is rotated at a high speed, the magnetic tape 70 runs obliquely along the tape running surface 21 and the helical lead 22 formed on the outer peripheral surface of the fixed cylinder 20, and is obliquely scanned at a constant pitch by the magnetic head 60. It is like this. The tip of the tip of the magnetic head 60 normally projects about 30 μm from the outer peripheral surface of the rotary cylinder 50. Therefore, the magnetic head 60 rotates with its tip end biting into the magnetic tape 70. Therefore, contact pressure is generated on the contact surface between the magnetic tape 70 and the magnetic head 60.

At the position where the magnetic tape 70 enters the tape running surface 21 of the fixed cylinder 20, the magnetic head 60 plunges into the magnetic tape 70, so that the magnetic tape 70 is suddenly lifted.
Conversely, from the tape running surface 21 of the fixed cylinder 20 to the magnetic tape
At the position where 70 disengages, the magnetic head 60 also disengages, so that the contact pressure suddenly disappears. At any position, the magnetic tape 70 is vibrated due to the abrupt change in the contact pressure, and the image is adversely affected such as distorted.

As a means for reducing the momentary vibration of the magnetic tape 70, the tape running surface 21 of the fixed cylinder 20 is inserted,
It is effective to provide minute protrusions that come into contact with the magnetic tape 70 at the corresponding head entry position C and head removal position (see FIG. 6) on the outlet side. By providing minute protrusions at the head plunging position C and the head detaching position D, the magnetic tape 70 is partially lifted when the magnetic head 60 is plunged into or ejected, and the magnetic tape 70 is momentarily changed due to a sudden change in contact pressure. Vibration is suppressed.

The cylinder 20
A conventional method for forming the tape is to provide a slight amount of uncut portion on the tape outlet side when processing the tape running surface 21 and the helical lead 22 of the fixed cylinder 20. Further, a method of plastic working in which the tape running surface 21 of the fixed cylinder 20 and the helical lead 22 are processed by a dedicated processing machine and then projections are formed by a press or the like in another step is also used in some cases.

<Problems to be Solved by the Invention> The former method of cutting uses that the processing of the helical lead 22 starts from the exit side of the tape running surface 21, and the head detachment position on the exit side of the tape running surface 21 is used. After processing a minute protrusion on D, the cutting amount of the cutting tool is increased to process the tape running surface 21 other than the protrusion to a predetermined cylinder outer diameter. In this method, it is impossible to provide a projection similar to that on the exit side on the entrance side of the tape running surface 21, and it is also a helical shape that the projection on the exit side can be changed in shape or displaced in position. It is also difficult in relation to the shape of the lead 22.

On the other hand, in the latter method by plastic working, the protrusion can be worked at any position. However, in order to do so, a dedicated jig is needed. In particular, when it becomes a jig that can process protrusions on both the inlet side and the outlet side of the tape running surface 21,
The structure becomes complicated and problems such as difficulty in adjusting the angle setting occur. Actually, the position accuracy of the protrusion needs to be about ± 0.5 ° from the reference position of the helical lead 22. With the above jig, it is difficult to adjust and it is difficult to maintain the accuracy due to wear due to the large number of parts. There were many problems.

The present invention has been made in view of the above circumstances, and provides a method for processing a rotary magnetic head cylinder capable of forming a protrusion for preventing tape vibration at an arbitrary position of a fixed cylinder with good accuracy and easily. The purpose is to provide.

<Means for Solving the Problems> A method of machining a rotary magnetic head cylinder according to the present invention is a method of machining a fixed cylinder used in a rotary magnetic head cylinder of a helical scan system, and is a method for machining a spindle end of a numerically controlled lathe. After the fixed cylinder is clamped on the chuck, the tape guide surface and the helical lead are formed on the fixed cylinder by the equipment provided on the tool rest of the numerical control lathe, and then the fixed cylinder is provided on the tool holder of the tool rest. The drum holder is brought into contact with the tool holder, and in this state, the tip of the pressing tool detachably attached to the tool holder is moved by the operation of the numerically controlled lathe to bring the tip into contact with the inner peripheral wall of the fixed cylinder. A protrusion for preventing tape vibration is formed on the peripheral wall of the fixed cylinder.

<Operation> By rotating the spindle of the numerically controlled lathe, it is possible to easily guide an arbitrary position in the circumferential direction of the peripheral wall of the fixed cylinder to the machining position. The positioning accuracy of the main shaft in the rotating direction is about ± 0.1 ° in a normal numerically controlled lathe, and the rotating cylinder does not move due to the drum holder even if the tip of the pressing tool contacts the inner peripheral wall of the fixed cylinder. Satisfies the positional accuracy required for the protrusion for preventing tape vibration formed on the peripheral wall of the fixed cylinder. By exchanging the pressing tool, protrusions of any shape can be formed.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram for explaining a schematic configuration of a numerically controlled lathe, FIG. 2 is an enlarged perspective view around a spindle for explaining the processing method of the present invention, and FIG. 3 is a sectional view of a jig holder. FIG. 4 is a sectional view of a main part of a rotary magnetic head cylinder showing a protrusion formed on the tape traveling surface outlet side of the fixed cylinder.

First, a numerically controlled lathe to which the method of the present invention is applied will be described. As shown in FIG. 1, the numerically controlled lathe A is a device mainly used for forming the tape guide surface 21 and the helical lead 22 of the fixed cylinder 20, and the feature of the present invention is that this device is used. The tape vibration preventing projections 23 are formed on both the entrance side and the exit side of the tape running surface 21 (the head entry position C and the head removal position D also shown in FIG. 5). Explaining this schematic configuration, the spindle 10 supported vertically is connected to a spindle motor 11 and a position coder 12, respectively, and the rotation angle is detected by the position coder 12.
It is adapted to be rotationally driven by a spindle motor 11. A chuck 13 is attached to the lower end of the main shaft 10, and a claw 14 for clamping the fixed cylinder 20 is fixed to the chuck 13. At the tip of this claw 14,
As shown in FIG. 2, a positioning pin 141 is provided, and by this positioning pin 141, the claw 14 and the fixed cylinder 20 are provided.
It is designed to be in phase with.

On the other hand, a tool rest 80 of the numerically controlled lathe A is arranged below the spindle 10. The tool rest 80 is controlled in position by three axes by an X-axis servo motor 82, a Y-axis servo motor (not shown), and a Z-axis servo motor 83. Moreover, on the surface of the tool rest 80, although not shown, in addition to the equipment necessary for forming the tape guide surface 21 and the helical lead 22, etc., a tool holder having a pressing tool 30 and a drum holder 40. 81 is equipped.

Details of the tool holder 81 will be described with reference to FIG. The upper surface of the tool holder 81 has a pressing tool such as a punch.
A drum holder 40, which is substantially pipe-shaped, is attached on top of which 30 is detachably attached. Meanwhile, the tool holder 81
Inside the drum holder 40 corresponding to the lower position of the drum holder 40, a crimp spring 811 and a bearing 812 are respectively provided, so that the drum holder 40 can be expanded and contracted and rotated with respect to the tool holder 81 in the vertical direction in the drawing. Has become.

Next, a method of forming the tape vibration preventing projection 23 on the fixed cylinder 20 using the numerical control lathe A as described above will be described.

First, the fixed cylinder 20 is clamped by the claws 14 of the chuck 13 at the lower end of the spindle 10. Clamped fixed cylinder 20
Has a side facing the rotary cylinder facing downward. In addition, the positioning pin 141 protruding from the claw 14 is attached to the fixed cylinder 2
By inserting the holes into the corresponding holes of 0, the phases of the main shaft 10 and the fixed cylinder 20 are matched.

Then, in order to form the protrusion 23 at the head detachment position D (see FIG. 5) located on the outlet side of the tape guide surface 21 of the fixed cylinder 20, the main shaft 10 is rotationally driven by the rotational phase control. Then, the spindle motor 11 is stopped at the timing when the spindle 10 is guided to the machining position of the head detachment position D.
In parallel with this (or before and after this), the tool rest 80 is moved to press the tip of the drum holder 40 against the inner wall surface of the fixed cylinder 20. Then, the crimp spring 811 provided in the tool holder 81 is slightly contracted, and the fixed cylinder 20 is held. Next, the tip of the pressing tool 30 is moved in the radial direction of the fixed cylinder 20 by moving the tool rest 80 while maintaining the holding state of the fixed cylinder 20 by the drum holder 40. Then, the tip of the pressing tool 30 is brought into contact with the inner peripheral wall of the fixed cylinder 20 at a position corresponding to the head detachment position D. Further, the tip end portion of the pressing tool 30 is pressed against this portion of the fixed cylinder 20 until a predetermined protrusion amount is obtained from the inner side of the inner wall of the fixed cylinder 20 in the radial direction. Then, a protrusion 23 is formed at the head detaching position D located on the outlet side of the tape guide surface 21 of the fixed cylinder 20 (see FIG. 4).

Then, the tool rest 80 is moved again to retract the tip of the pressing tool 30 from the inner peripheral wall of the fixed cylinder 20. And
With the tip of the drum holder 40 pressed against the inner wall of the fixed cylinder 20, the main shaft 10 is rotated to guide the tip of the pressing tool 30 to the machining position of the head thrusting position C of the fixed cylinder 20. After that, the projection 23 is formed at the head entry position C of the fixed cylinder 20 in the same manner as described above. When the head entry position C is formed on the fixed cylinder 20, the tool rest 80 is moved to retract the pressing tool 30 and the drum holder 40 from the fixed cylinder 20 and return them to the original state, and The fixed cylinder 20 clamped by the claw 14 of the chuck 13 is removed. The fixed cylinder 20
In order to further improve the projection amount accuracy of the projection 23 formed at the head plunging position C and the head detaching position D, after the projection 23 is formed at the head plunging position C and the head detaching position D, the tip portion of the pressing tool 30 is removed. It is moved in the axial direction for finishing cutting.

As described above, in the processing method of the rotary magnetic head cylinder according to the present invention, after the tape running surface 21 and the helical lead 22 of the fixed cylinder 20 are processed by using the numerical control lathe A, the fixed cylinder 20 is changed to the numerical control lathe A. The protrusions 23 for preventing tape vibration can be formed with the tape mounted. Moreover, unlike the conventional method, the protrusions 23 can be formed at arbitrary positions of the fixed cylinder 20, that is, both the inlet side and the outlet side of the tape running surface 21. Further, the positioning accuracy in the rotational direction of the main shaft 10 of the numerically controlled lathe A is usually about ± 0.1 °, and when the projection 23 is formed, the tip of the pressing tool 30 comes into contact with the inner peripheral wall of the fixed cylinder 20. Since the drum holder 40 is devised so that the fixed cylinder 20 does not move, the position accuracy and the projection amount accuracy of the projection 23 formed on the fixed cylinder 20 sufficiently meet the requirements. Further, there is an advantage that the protrusion 23 having an arbitrary shape can be formed by replacing the pressing tool 30. Therefore, it is of great significance in efficiently producing the fixed cylinder 20 with high processing accuracy.

The processing method of the rotary magnetic head cylinder according to the present invention is not limited to the above-described embodiment, and the structure of the drum holder is not limited to that described above, and the drum holder is fixed to the fixed cylinder clamped to the chuck of the numerical control lathe. May be contacted by any method.

<Effects of the Invention> In the case of the method for processing a rotary magnetic head cylinder according to the present invention, a numerical control lathe is used to form projections for preventing tape vibration in both the head entry position and the head removal position of a fixed cylinder in one step. The protrusions can be formed continuously, and the protrusions can be formed easily with high accuracy in terms of the method of forming protrusions. Furthermore, since the pressing tool is detachable, it is possible to replace the pressing tool without changing the movement amount of the tool base, that is, without changing the program input to the numerically controlled lathe. The position and shape of the protrusion can be easily changed. Therefore, it has great significance in efficiently producing a fixed cylinder with high processing accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 4 are views for explaining one embodiment of the processing method of the present invention, and FIG. 1 is a schematic diagram for explaining a schematic configuration of a numerically controlled lathe. Fig. 2 and Fig. 2 are enlarged perspective views around the main shaft for explaining the processing method of the present invention, Fig. 3 is a sectional view of a jig holder, and Fig. 4 shows a protrusion formed on the tape running surface outlet side of a fixed cylinder. It is a principal part sectional view of the rotating magnetic head cylinder shown. FIGS. 5 to 7 are views for explaining the conventional method. FIG. 5 is a side view of the rotary magnetic head cylinder, and FIG. 6 is a rotary magnetic head showing a magnetic tape running. Top view of cylinder, 7th
The figure is a cross-sectional view of the main part of the rotary magnetic head cylinder showing the exit side of the tape running surface. A: Numerical control lathe 10 ... Spindle 13 ... Chuck 20 ... Fixed cylinder 23 ... Projection 30 ... Pressing tool 40 ... Drum holder 80 ... Turret

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hajime Nagahashi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Ichiro Okabe 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (56) Reference JP-A-1-106354 (JP, A)

Claims (1)

(57) [Claims] 1. A machining method for a fixed cylinder used in a rotary magnetic head cylinder of a helical scan system, wherein a tool rest of a numerically controlled lathe is clamped on a chuck at a spindle end of the numerically controlled lathe. After the tape guide surface and the helical lead are formed on the fixed cylinder by the equipment installed on the fixed cylinder, the drum holder provided on the tool holder of the tool post is brought into contact with the fixed cylinder, and in this state, the tool holder is detachably attached. Move the tip of the attached pressing tool by the operation of the numerically controlled lathe,
A method of processing a rotary magnetic head cylinder, wherein the tip portion is brought into contact with an inner peripheral wall of the fixed cylinder to form a protrusion for preventing tape vibration on the peripheral wall of the fixed cylinder.