JP2002001607A - Machining method for upper drum, rounded end mill, and upper drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machining method for an upper drum capable of always uniformly machining a rounded curve of an edge of a window part for mounting a magnetic head. SOLUTION: In this rounded shape forming method for the upper drum for cutting the edges e, e1, e2 of the window part 7 for mounting the magnetic head 4 provided on the upper drum 3 constituting a rotary drum 1 used in DAT, VTR and the like into a rounded curve with designated dimensions, a R-shaped end mill 10 having a cutting blade 10B for forming the rounded curve and a complementary inverted rounded curve by rotation, and the window part 7 is bored by the cutting blade 10B, and the edges e, e1, e2 are cut into the rounded curve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drum for magnetically recording / reproducing signals on a magnetic tape in a helical scan type magnetic recording / reproducing apparatus such as a DAT (digital audio tape recorder) or a VTR (video tape recorder). The present invention relates to a method of processing an upper drum for processing an upper drum, an R-shaped end mill used in the processing method, and an upper drum manufactured by the processing method.

[0002]

2. Description of the Related Art In a helical scan type magnetic recording / reproducing apparatus, a magnetic head is mounted and fixed on an upper drum constituting a rotating drum, and the magnetic tape is caused to run obliquely with respect to the rotating drum. Recording of information by helical scanning of the magnetic head,
Perform playback.

[0003] As a structure of a rotary drum used in this helical scan type magnetic recording / reproducing apparatus, for example, there is one shown in FIG. The rotary drum 1 shown in FIG. 8 includes a fixed lower ram 2, a rotatable upper drum 3, and a magnetic head 4 integrally attached to the upper drum 3. The lower ram 2 is provided with a lead surface 5 for guiding a magnetic tape. The rotating drum 1 runs obliquely with a part of the magnetic tape 8 (shown by broken lines) wound around the upper drum 3 and the tape running surface 6 of the lower ram 2 along the lead surface 5. The magnetic head 4 rotating integrally with the upper drum 3 performs helical scanning of the magnetic tape 8 to record and reproduce information.

A window 7 is formed in a part of the peripheral surface of the upper drum 3 so as to slightly protrude the tip of the magnetic head 4 outward. As shown in FIG. 9, the upper drum 3 rotates at a high speed and the magnetic head 4
It is required that the burrs be polished so that the magnetic tape 8 is not damaged by the burrs (corners) at the edge portion e of the window portion 7 when the magnetic tape 8 is helically scanned. Buffing is used as an example of this polishing method. The buffing is a process in which buffed skin coated with buff powder (alumina abrasive) is pressed against the burrs of the edge portion e while rotating, and this portion is polished smoothly (R-shaped curved surface) to remove burrs. Is the law.

[0005]

As described above, burrs at the edge portion e are polished by buffing. At this time, depending on the pressing force of pressing the buff skin against the burrs, the burrs are formed on this portion. As a result, the size and unevenness of the R-shaped curved surface are generated, and as a result, it is impossible to always perform the R-shaped curved surface processing with uniform dimensions on the edge portion e.

In addition, when the buffing is repeatedly performed, the buffing skin itself is worn, and even if the pressing force for pressing the buffing skin against the burr is constant, the position where the buffing skin is pressed, the pressing force, and the pressing area. Delicately changes, and it is not possible to constantly perform uniform R-shaped curved surface processing. Further, although the processed R shape is specifically quantified in the buffing instruction, as described above, the uniform R-shaped curved surface processing cannot always be performed by the buffing. For this reason, at the time of the quality judgment after the buffing, the quality judgment is made by visually checking the R-shaped curved surface processed portion. As a result, R-shaped curved surface processing cannot be performed with high accuracy at the dimensions specified in the buffing instruction sheet. Furthermore, the above-mentioned buffing is performed as a post-process of the drilling process of providing the window portion 7 using the drilling mill.

In view of the above, the present invention is a method of processing an upper drum for cutting an edge of a window portion for mounting a magnetic head provided on the upper drum into an R-shaped curved surface having a predetermined dimension. Rotating an R-shaped end mill provided with cutting teeth for forming a complementary inverted R-shaped curved surface at its tip, pressing the tip of the R-shaped end mill in a rotating state against a processing position of the upper drum, By drilling the window portion having a predetermined diameter by cutting teeth, and by cutting the edge of the window portion into the R-shaped curved surface, it is possible to always perform a uniform R-shaped curved surface processing on the edge, In addition, since the cutting has high accuracy, it is possible to perform the R-shaped curved surface processing with a numerical value according to the processing instruction, and furthermore, it is possible to simultaneously perform the step of forming the window portion and the R-shaped curved surface processing of the edge at a time. So raw Processing methods of the upper drum can be enhanced sexual, R shape end mill used in this processing method, and an object thereof is to provide a upper drum made by this working method.

[0008]

In order to achieve the above object, the present invention provides an upper drum processing method, an R-shaped end mill, and an upper drum having the following constitutions (1) to (3). (1) As shown in FIGS. 1 to 4, a magnetic head 4 (provided on an upper drum 3 constituting a rotary drum 1 (FIG. 8) used in a helical scan type magnetic recording / reproducing apparatus (DAT, VTR, etc.)) 9) The edges e, e1 and e2 of the mounting window 7 are formed into an R-shaped curved surface having a predetermined dimension (at least the diameter φD2 of the window 7 and the distances W1 and W2 between the openings of the window 7 as shown in FIG. 3). , A curvature R1 of the edge e and an R-shaped curved surface dimensioned by predetermined dimensions of the opening angle θ1 of the edge e), which are complementary to the R-shaped curved surface. A cutting tooth 10B for rotatingly forming an inverted R-shaped curved surface (length 17 and diameter φ shown in FIG. 4)
R2, an R-shaped end mill 10 having a virtual inverted R-shaped curved surface formed by rotating the cutting tooth 10B having a curved surface shape defined by the opening angle θ2 at least once, at the tip 10A, and rotating the end mill 10. The end 10A of the R-shaped end mill 10 is pressed against the processing position of the upper drum 3 to pierce the window 7 having a predetermined diameter (diameter φD2) with the cutting teeth 10B, and The edges e, e1 and e2 of the window 7 are formed into the R-shaped curved surface (as described above, at least the diameter φD2 of the window 7 and the window 7).
(A predetermined shape of the distances W1 and W2 of the opening, the curvature R1 of the edge e, and the opening angle θ1 of the edge e). (2) As shown in FIG. 4, an R-shaped end mill 10 used in the method for processing an upper drum according to claim 1, wherein a window 7 of the upper drum 3 is formed with a predetermined diameter (diameter φD2). And the edges e, e1,
e2 is the R-shaped curved surface (length 17; diameter φR2; opening angle θ)
2. An R-shaped end mill comprising cutting teeth 10B capable of being cut on an R-shaped curved surface defined by the formula (2). (3) As shown in FIG. 3, the upper drum 3 processed by the method for processing an upper drum according to claim 1, wherein the R-shaped curved surface of the edge of the window portion for attaching the magnetic head (at least the window portion 7). ΦD2, the distance W of the opening of the window 7
1, W2, curvature R1 of edge e, opening angle θ1 of edge e
R shape that is dimensioned by each predetermined dimension of)
An inverted R-shaped curved surface (length 17, diameter φR) formed by the cutting teeth 10B when the R-shaped end mill 10 is rotated.
2. An upper drum characterized by having a curved surface complementary to a virtual inverted R-shaped curved surface formed by rotating the cutting teeth 10B having a curved surface shape defined by the opening angle θ2 at least once. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of a processing apparatus using the upper drum processing method of the present invention, FIG. 2 is a diagram for explaining the procedure of the upper drum processing method of the present invention, and FIG. 3 is a diagram of the upper drum of the present invention. FIG. 4 is an enlarged view showing the R-shaped end mill of the present invention, FIG. 5 is a partial enlarged view showing the entire view of the window of the upper drum before buffing and the right side of the window, and FIG. FIG. 7 is a partially enlarged view showing the entire window and the right side of the window of the upper drum processed by the processing method of the present invention. The same portions as those described above are denoted by the same reference numerals, and description thereof will be omitted.

The method for processing an upper drum according to the present invention is performed using a processing apparatus having a block configuration shown in FIG. As shown in FIG. 1, the processing apparatus includes an operation unit AA for inputting processing start / end and the like, and a controller BB for controlling each unit of the processing apparatus based on input signals such as processing start / end input via the operation unit AA. , A driver CC for rotating and raising / lowering the R-shaped end mill 10 in response to a command from the controller BB, and a window 7 for holding the unprocessed upper drum 3 during processing. The driver CC described above has a rear end portion of the R-shaped end mill 10 fixedly detachably fixed thereto, and rotates the R-shaped end mill 10 in the direction a in FIG. When the cutting teeth of the R-shaped end mill 10 are in the opposite direction, the R-shaped end mill 10
Of course. The driver CC moves the rotating R-shaped end mill 10 up and down in the direction b in FIG.

The above-mentioned R-shaped end mill 10 is shown in FIG.
As shown in the side view of (a), the tip 10A, the cutting tooth 1
0B, a rear end 10C, and a cutting groove 10D. As shown in FIGS. 4B and 4C, the tip 10A has cutting teeth 10B that can cut the edge e of the window 7 of the upper drum 3 into an R-shaped curved surface having a predetermined dimension. Rear end 10C
Is a portion which is fixed to the driver CC so as to be able to be inserted and removed. 4B is a bottom view of the tip 10A, and FIG. 4C is an enlarged view of a portion surrounded by a circle A shown in FIG. In addition, the rotation locus drawn by the cutting teeth 10B of the tip 10A of the R-shaped end mill 10 in the rotating state (10A shown in FIG. 3B)
A) is a locus complementary to the R shape formed on the edge e after the cutting teeth 10B of the tip 10A cut the edge e of the window 7 of the upper drum 3.

The procedure for processing the upper drum 3 performed by the above-described processing apparatus is as follows. (1) The upper drum 3 in which the window 7 is unprocessed (see FIG. 2)
(A) From above, an R-shaped end mill 10 in a rotating state.
To abut on the portion where the window portion 7 is to be formed, cut with a constant pressing force, pierce the window portion 7 having a predetermined diameter, and form an R-shaped edge on the upper surface 3 a of the upper drum 3. e,
e1 and e2 are formed (perforating end milling by machining shown in FIG. 2B). (2) When the window 7 having a predetermined diameter and the R-shaped edge e having a predetermined dimension are formed, the R-shaped end mill 10 moves up again. (3) Next, using the cutting tool B of the processing device, R chamfering of the outer peripheral portion 3b of the upper surface within the tape running diameter 8a of the upper drum 3 is performed (shown in FIG. 2C.
R-chamfering is performed on a corner of the outer peripheral portion of the upper drum 3 which is in contact with the tape running path 8a adjacent to the window 7 surface. R chamfering turning with a lathe). As a result, the corners of the upper drum 3 that are in contact with the tape running path 8a are processed into a three-dimensionally smooth curved surface shape.

The R shape of the window 7 and the edge e of the upper drum 3 processed by the above-described processing method has the shape and dimensions shown in FIG. 3A is a side view of the window 7, FIG. 3B is a plan view of the window 7, and FIG.
FIG. 3C is a partially enlarged view of a Z part in FIG. As an example, the dimensions associated with the window 7, edge e of the upper drum 3 are as follows. The diameter φD1 of the upper drum 3 is 62 mm, the diameter φD2 of the window 7 is 7 ± 0.15 mm, and the shortest distance W1 of the opening of the window 7 is 4.1 mm to 4.1+.
0.3 mm, maximum opening distance W2 of window 7 = 4.4 mm to 4.4 + 0.
3 mm, length e1 of edge e = 0.6 mm, length l2 of edge e = 0.765 mm, length l3 of edge e = 0.3 mm to 0.3 + 0.1 m
m, length e4 of edge e = 0.36 ± 0.23 mm, curvature R1 of edge e = 0.5 ± 0.02 mm, opening angle θ1 of edge e = 120 ± 2 °.

An R-shaped end mill 10 for cutting the R-shaped windows 7 and edges e of the processed upper drum 3 shown in FIG. 3 has the shape and dimensions shown in FIG. The total length 15 of the R-shaped end mill 10 = 60 mm, the length 16 of the cutting groove 10D = 15 mm, the length 17 of the tip 10A for forming the R shape = 0.5 mm, and the diameter φR1 of the rear end 10C = 10 mm to 10-0. .01m
m, diameter φR2 of tip 10A = 0.5 ± 0.02 mm, opening angle θ2 of tip 10A = 31 ° ± 15 ′.

As shown in FIGS. 7 (a) and 7 (b), the R shape formed on the edge e of the window 7 of the upper drum 3 by the above-described method of processing the upper drum according to the present invention has the processed surface. But smooth and glossy (high reflectivity). On the other hand, a conventional upper drum before buffing (FIG. 5)
The R shape after buffing (a), (b)) is shown in FIG.
As shown in (a) and (b), there is no gloss (low reflectance). As a result, it is determined whether the R-shaped curved surface of the edge e is formed by either the processing method of the present invention or the buffing method, based on the difference in the glossiness of the processed surface (high or low reflectance). Depending on the shape of the edge, it can be easily visualized.

[0016]

As described in detail above, the present invention relates to a method of processing an upper drum for cutting an edge of a window for mounting a magnetic head provided on the upper drum into an R-shaped curved surface having a predetermined dimension. And an inverse R complementary to the R-shaped surface
Rotating an R-shaped end mill provided with cutting teeth at the tip, which rotationally forms a curved surface, presses the tip of the R-shaped end mill in a rotating state against a processing position of the upper drum,
By drilling the window portion having a predetermined diameter by the cutting teeth and cutting the edge of the window portion into the R-shaped curved surface, it is possible to always perform a uniform R-shaped curved surface processing on the edge. In addition, since the cutting is performed with high accuracy, it is possible to perform the R-shaped curved surface processing with the numerical values according to the processing instruction, and it is possible to simultaneously perform the step of drilling the window and the R-shaped curved surface processing of the edge at a time. Therefore, it is possible to provide an upper drum processing method capable of improving productivity, an R-shaped end mill used in this processing method, and an upper drum manufactured by this processing method.

[Brief description of the drawings]

FIG. 1 is a block diagram of a processing apparatus when an upper drum R forming method of the present invention is used.

FIG. 2 is a diagram for explaining a procedure of an upper drum R forming method of the present invention.

FIG. 3 is a diagram for explaining the R shape of the edge of the upper drum processed by the upper drum R forming method of the present invention.

FIG. 4 is an enlarged view showing an R-shaped end mill used in the upper drum R forming method of the present invention.

FIG. 5 is a partially enlarged view showing the entire view of the window of the upper drum before buffing and the right side of the window.

FIG. 6 is a partially enlarged view showing the entire view of the window of the upper drum after buffing and the right side of the window.

FIG. 7 is a partially enlarged view showing the entire view of the window portion and the right side of the window portion of the upper drum processed by the processing method of the present invention.

FIG. 8 is a diagram for explaining a structure of a rotary drum.

FIG. 9 is a partially enlarged view of an upper drum on which a magnetic head is mounted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary drum 3 Upper drum 4 Magnetic head 7 Window 10 R-shaped end mill 10A Tip 10B Cutting teeth e, e1, e2 Edge

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C022 AA00 AA03 AA08 AA10 DD05 DD11 GG03 KK01 KK06 KK25 5D036 AA14 BB12 CC03 GG01

Claims (3)

[Claims] An upper for cutting an edge of a window for attaching a magnetic head, provided on an upper drum constituting a rotary drum used in a helical scan type magnetic recording / reproducing apparatus, into an R-shaped curved surface having a predetermined dimension. A method of processing a drum, comprising: rotating an R-shaped end mill provided with cutting teeth at a tip thereof, which rotationally forms an inverted R-shaped curved surface complementary to the R-shaped curved surface; It is characterized in that the window portion having a predetermined diameter is bored by the cutting teeth by pressing against the processing position of the upper drum, and the edge of the window portion is cut into the R-shaped curved surface. Processing method of upper drum. 2. An R-shaped end mill used in the method of processing an upper drum according to claim 1, wherein the window portion of the upper drum is formed with a predetermined diameter, and the edge of the window portion is formed with the R edge. An R-shaped end mill characterized by comprising cutting teeth capable of cutting on a curved surface. 3. An upper drum processed by the method of processing an upper drum according to claim 1, wherein an R-shaped curved surface of an edge of the window portion for attaching a magnetic head rotates the R-shaped end mill. An upper drum having a curved surface complementary to an inverted R-shaped curved surface formed by the cutting teeth.