JPS61230860A - Tape drum processing equipment - Google Patents

Abstract

PURPOSE:To process the tape running surface and tape lead surface of a tape drum simultaneously by furnishing a moving table controlled in the perpendicular direction by command signals and a cam tracing device installed on said moving table. CONSTITUTION:A lower drum W having a tape running surface and a tape lead surface is chucked on a spindle 48 driven by a DC servo motor 49 through a speed reduction device R together with a bell cam 4. An X-axis table 40 and a Y-axis table 41 are moved in the X and Y directions by motors 42 and 43, respectively, and controlled by feeding command signals given by an NC device. A grinding device 44 mounted on a bell cam device 45 is installed on the X-axis table 40. A work W machined under numerical control for its X- and Y-axis feeds is rotated at a low speed, and the tape running surface and tape lead surface are chucked at a single action and processed simultaneously with high precision. It is also possible to process a hard drum with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Overview] The present invention relates to a tape drum processing device, and particularly to a processing device for a fixed lower drum for a tape guide in a video tape recorder (VTR) or the like.

[Prior art]

A conventional videotape drum assembly used, for example, in a home VTR, is equipped with a fixed lower drum W and a plurality of video heads H, and rotates as shown in FIG. The videotape T is wound diagonally over approximately half or more of the cylindrical side surface of the fixed lower drum W and the rotating upper drum U through a plurality of guides G, and the upper drum U is driven to rotate. The video head H is caused to scan the video tape T that is being run.
Video signals are being recorded/played. In this case, the cylindrical side surface of the fixed lower drum W includes a tape running surface 1 and a tape lead surface (guide surface) 2 for guiding one end edge of the tape.
is provided.

Conventionally, the tape running surface 1 and the tape lead surface 2 of a fixed lower drum W for this type of VTR have been turned using an automatic lathe in conjunction with a cam copying device. In this turning method, together with the fixed lower drum W, which is the workpiece to be turned, the lift amount of the tape lead surface 2 (the third
(see diagram) on the Pelcam surface with a lift amount equivalent to
A copying device, commonly known as a lead turner, mounted on the tool post and equipped with a cutting tool for tape running surface 1 and a cutting tool for tape lead surface 2 is brought into contact with the workpiece W to create a lead shape corresponding to a cam lift. It is then transferred to a computer and processed into a predetermined shape.

FIG. 2 shows a side (partial) view of an essential part of an example of a conventional processing device for a fixed lower drum for a VTR of this type. The fixed lower drum W, which is the workpiece to which the tape running surface 1 and the tape lead surface 2 are to be cut, is chucked to the rotating main shaft 32, and the tape running surface turning tool 29 and tape lead mounted on the tool rest 27 are mounted on the rotating main shaft 32. Processing is performed using a surface turning tool 28. The tool rest 27 is fixed on a sleeve 30 fitted onto the shaft 26, and can be moved in the direction of left and right arrows A in the figure by means of a guide section 31. Further, a copying bell cam 23 is fixed concentrically to the main shaft 32 and rotates together with the main shaft, and a predetermined copying cam contour surface 2 is formed on the end surface of the bell cam 23 on the work W side.
3a is formed, and a cam 7 and an lower roller 24 rotatably supported on a pin 25 fixed in the diametrical direction perpendicular to the shaft axis at the left end of the shaft 26 as seen in the drawing are attached to the contour surface of the copying cam. 23a by a pressing means (not shown).

Next, an outline of the W machining method in the machining apparatus having the above configuration will be explained. The tape running surface turning cutting tool 29 on the tool rest 27 is located at 29' indicated by a two-dot chain line at the start of turning.

The cam 7 lower roller 24 at the end of the shaft 26 is pushed to the left in the figure while being guided by the guide section with the shaft 26, sleeve 30, tool rest 27, and piston 29, 28 integrated. It comes into contact with the cam contour surface 238 of the bell cam 23 that rotates together with the main shaft, and is driven to rotate following this cam surface. Therefore, the cutting tool 29 repeats horizontal reciprocating motion in the six directions of the arrows by an amount corresponding to the cam lift amount of the cam contour surface 23a, but at this time, the cutting tool 29 is not in contact with the workpiece W yet.

Next, a drive means (not shown) is activated to gradually move the sleeve 30 to the left in the figure relative to the shirt 26.

Therefore, the cutting tool 29 fixed to the tool rest 27 is
Gradually moving leftward from the dotted chain line position 2γ to the 29″ position, the cutting tool 29 advances to the position shown by the solid line and comes into contact with the workpiece W which is rotationally driven by the main shaft 32, turning the tape running surface 1. Start.

Next, the tape lead surface 2 is formed by copying the bell cam 23.
This section explains turning. After the cutting tool 29 which is in contact with the tape running surface 1 is retracted as a whole above the radial direction (cutting direction) of the workpiece W together with the tool post 2T by the operation of a driving means (not shown), 30 to the right in the figure relative to the shaft 26, and the drive means moves the sleeve 30, shaft 26, cam follower roller 24, and tool rest 27 in the opposite direction to the retraction movement, that is, downward in the radial direction of the workpiece W. By moving the whole part, the cutting time for tape lead surface turning can be reduced to 2 days.
The tape lead surface 2 of the workpiece W is brought into contact with the cam contour surface 2.
Turn the tape lead surface 2 by tracing 3a.

However, the conventional processing method described above has the following problems.

That is, FIGS. 3(4) and 3(B) are developed views of the tape running surface 1 and tape lead surface 2 of the fixed lower drum, respectively. Regarding conventional drums, the figure (B) shows, for example, a VTR with a digital audio recording function, or
This invention relates to a drum for, for example, 8 cod tape, which is compatible with lightweight and compact V'I'H. IN is the tape entrance,
OUT is the tape outlet, and L is the tape lead surface glue 7
(ie, the same as the lift amount of the bell cam contour surface 23a). (As can be seen in the comparison between Figures (Rotation) and (B), the shape of each F shape (wrapping angle, lead angle, cam lift C, etc.) is significantly different, and the normal drum in Figure (A) has a different The straight part a1 corresponding to an angular angle of 180° and the relief part b1 corresponding to an angle of about 1800 are (
B) The straight M portion a2 and relief portion b2 corresponding to the winding angle of 340° in the figure, and therefore the relief portion angle of approximately 20°, are as follows:
Although they are significantly different for the same lift fIkC, both require lead linearity of about 1Jm and roundness and concentricity of the tape running surface of about 1-1.

Therefore, in the conventional bell cam copying process, when the tape winding angle is as large as about 3400 degrees as shown in FIG. When turning surface 2, the cam lift amount rapidly returns to zero in this part, so in the conventional cam copying device, the cam surface 23a and the cam 7 roller 24
However, in particular, it was not possible to properly track the tape from the relief part b2 to the tape entrance IN part, and the lead linearity in the lead straight part a2 could not be processed to a predetermined precision. Furthermore, since the cutting resistance in the above part changes rapidly,
Chipping of the diamond bite occurred and it could not be put to practical use.

Furthermore, in order to prevent deterioration of image quality due to wear when the videotape T runs in contact with the tape running surface 1 and the tape lead surface 2, a hard material (for example, a Vickers hardness H muff of 00-1,800°, Linear expansion coefficient 7-11
(Alumina ceramic, silicon nitride, etc. at approximately 107°C)
This is one of the reasons why the adoption of this type of hard material has not yet been realized, as it is impossible to cut the drum using a material such as silicone. Eutectic aluminum alloy (Bitsukama hardness Hv140', coefficient of linear expansion 23X10/'C
At present, the following methods are used: This material is also relatively expensive.

〔the purpose〕

The present invention has been made in view of the problems of the prior art as described above, and at the same time eliminates the drawbacks of the prior art,
It is an object of the present invention to provide a tape drum processing device that can process a fixed lower drum for a tape guide such as a TR with high precision and low cost, and at the same time can process the drum using a hard material.

〔Example〕

The present invention will be explained below based on examples. Figure 4 shows
This is an enlarged cutaway side view of a main part showing an embodiment of a grinding device according to the present invention, in which a grinding wheel 3 attached to the grinding device (not shown) has its axis aligned with a workpiece W chucked to the main shaft of the processing device. It is shown arranged perpendicularly to the detail. The grindstone 3 is mounted on a cam copying device of a grinding device, and grinds the tape running surface 1 and lead surface 2 of the workpiece W. The movement position of the rotation center of the grinding wheel 3 mounted on the cam copying device is such that the rotational trajectory of the grinding wheel is on the tape running surface 1 of the workpiece W.
and each cutting point position of the tape lead surface 2. FIG. 4(4) shows a case where a grindstone for grinding the lead portion 2 and a grindstone 60, 61 for grinding the tape running surface 1 are attached to the grindstone holder 62 instead of the grindstone shown in FIG.

FIG. 5 shows a side view of the workpiece W seen from the back side (opposite side of the end face 3a) of the rotary grindstone 3 installed in the grinding device. Reference numeral 13 indicates the rotation center of the grindstone 3, and 16 indicates the rotation locus of the grindstone. The intersection point 14 between the rotation locus 16 of the grinding wheel 3 and the center drawer Hta of the workpiece W is the grinding point, and the angle formed by the workpiece center drawer line ta and the straight line connecting the grinding point 14 of the grindstone 3 and the rotation center 13 of the grindstone. θ is set to be equal to the angle θ formed by the tangent tC of the rotation locus 16 at the grinding point 14 and [tb, which is perpendicular to the diameter of the workpiece W passing through the grinding point 14, and the end surface 3a of the grindstone 3 is , are arranged parallel to the center line of the workpiece W.

The grinding wheel 3 whose rotational center position has been set as described above rotates the workpiece W by the main shaft of the processing device and moves the rotating grinding wheel in the direction of the workpiece axis.
The tape running surface 1 and the tape lead surface 2 can be ground with high precision.

The work W is rotated by rotating the main shaft of the processing device (preferably using a main shaft bearing, a hydrostatic air bearing, or an oil static field bearing) at a low speed, and moving the grinding wheel 3 in the direction of the axis of the work W. This is done by following the bellcam pattern described above.

FIG. 6 shows an overall schematic plan view of an embodiment of a fixed lower drum processing device equipped with the grinding device. The lower drum workpiece W having a tape running surface 1 and a tape lead surface 2 is driven by a reduction gear device R together with a pelcam 4 by a DC servo motor 49.
It is chucked to a main shaft 48 which is driven via the main shaft 48. X and Y are orthogonal coordinate axis directions, and 40 is the X axis (direction,
41 is a Y-axis (direction, movement) table. The X-axis table 40 is controlled to move in the illustrated X-axis direction by an X-axis table drive motor 42 based on a command signal output from a numerical control device (not illustrated). Also,
Similarly, the Y-axis table 41 is controlled to move in the illustrated Y direction by inputting a command signal output from a numerical control device (not shown) to the Y-axis table drive motor 43.

A grinding device 144 is mounted on a bell cam copying device 45 on the X-axis table 40 . Grinding equipment! A motor (not shown) for driving the grinding wheel 3 is attached to the ff144, and a hydrostatic air bearing is used as the wheel rotation bearing. A cam follower roller 47 is rotatably supported at the tip of the shaft 46 of the bell cam copying device 45 in the pel cam 4 direction, and is integrally pressed against the cam contour 48 surface of the bell cam 4 . Also, on the X axis Q and pull 40,
The fixed lower drum WO bearing part and the transformer stand mounting part (both not shown), etc., which are the workpieces, are moved to a predetermined dimension by numerical control in the X-axis and Y-axis directions. It is configured to perform turning operations with precision.

Although not shown, a dressing device for the grinding wheel 3 is disposed on the spindle housing side of the grinding device 44 in the radial and axial directions of the spindle for grinding the tape running surface 1 and tape lead surface 2 of one workpiece W. Dressing of the grinding wheel surface is done using the X-axis/Y-axis table 4, which is moved by numerical control.
0/41 allows dressing of both grindstone surfaces easily and with high precision.

As explained above, the workpiece W is rotated at a low speed,
The rotary grindstone 3 can grind the tape running surface 1 and tape lead surface 2 of the workpiece W with extremely high precision.

FIG. 7 shows a sectional view of an example of a fixed lower drum using a hard material. 50 is a pre-formed hollow cylinder made of a hard material such as alumina ceramic or silicon nitride. The material 51 is processed and integrated into the hard material hollow cylinder 50 by cold fitting or adhesive, and the transformer base mounting part 53, bearing part 52, and back surface of the drum are formed by the fixed lower drum processing machine according to the present invention. 54 etc., is turned with the diamond cutting tool, and the tape running surface 1 and tape lead surface 2 of the hard material part are cut with one chucking using the grinding wheel 3 of the bell cam copy grinding device 44. Because it can be ground and there is no need to change the chucking, it is possible to achieve the desired high precision (for example, 1
It is possible to carry out processing within β Han).

Further, a machining relief part (groove, etc.) of the grindstone may be provided at the intersection with both of the machined surfaces 1 and 2, and in this case, it goes without saying that the relief part does not need to be ground.

〔effect〕

As explained above, according to the present invention, the video tape winding angle of a VTR is larger than usual and the fixed lower drum has a small relief part, that is, a VTR drum for digital audio or a lightweight and compact drum. The tape running surface and tape lead surface of small-diameter drums, etc., can be easily machined with high precision in the same process by one chucking, and the high precision of drums using hard materials that cause less wear on both sides. We were also able to make processing possible.

[Brief explanation of drawings]

Figure 1 is a side view of essential parts of an example of a drum assembly for videotape, Figure 2 is a side view of essential parts of a conventional fixed lower drum processing device, Figure 3 (B) is a side view of essential parts of a conventional fixed lower drum processing device. FIG. 4 is an enlarged cross-sectional view of a main part of an embodiment of the grinding device according to the present invention, and FIG.
4) is a modified example of the grinding wheel shown in Fig. 4, Fig. 5 is a side view of the workpiece seen from the back side of the grinding wheel shown in Fig. 4, and Fig. 6 is an overall schematic plan view of an embodiment of the fixed lower drum processing device. , FIG. 7 is a sectional view of an example of a fixed lower drum using a hard material. 1... Tape running surface 2... Tape lead surface 3... Grinding wheel 4... Copying bell cam 40/41... X/Y Axis (directional movement) table 44... Grinding device 45... Bell cam copying device 47... Cam follower roller 48... Rotating main shaft ■... ...Video tape W...Fixed lower drum (work) Fig. 1 ts 3 Fig. 3 (A) Fig. 3 (B) ts 4 factors Fig. 114 (A)

Claims (1)

[Claims] It is equipped with a movable table whose movement is controlled in orthogonal axes directions by command signals, and a cam copy grinding device disposed on the movable table. A tape drum processing device characterized in that it is configured to simultaneously process.