JPS61230802A - Tape drum machining apparatus - Google Patents

Abstract

PURPOSE:To machine respective different reed drum highly accurately while to improve the availability of reed machining unit by employing a plurality of reed type cams. CONSTITUTION:A bell cam 23 having plural different reed type cam faces 23a, 23b is fixed to the lower drum machining unit for securing a tape guide especially for video tape recorder. When conversion machining a work W corresponding with the cam face 23a into a work W corresponding with the cam face 23b, the cutter table 27 is replaced/set such that the cutter 29 for tape travel face 1 and the cutter 28 for the tape reed face 2 will machine the work W. Then the cutter table 27 or the shaft 26 is moved in the arrow direction Z to contact the cam faces 23a, 23b against the cam follower 24 thus to perform conversion machining of work W.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] 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 diagonally wound over more than half of the cylindrical side surface of the fixed lower drum W and the rotating upper drum U through a plurality of guides G. A video head H is caused to scan a video tape T that is rotated and run;
Video signals are being recorded/played. In this case, the cylindrical side surface of the fixed lower drum W is provided with a tape running surface 1 and a tape lead surface (guide surface) 2 for guiding one end edge of the tape.

Conventionally, the tape running surface 1 and tape lead surface 2 of the fixed lower drum W for this type of VTR are manufactured using an automatic lathe.
Turning is performed using a cam copying device. This turning method uses a fixed lower drum W, which is the workpiece to be turned.
At the same time, a cutting tool for cutting the tape running surface 1 and a cutting tool for cutting the tape lead surface 2 are mounted on the tool rest on a bell cam surface having a lift amount corresponding to the lift amount of the tape lead surface 2 (see FIG. 3 below). A copying device commonly called a "lead turner" equipped with a cutting tool is brought into contact with the workpiece W to transfer the lead shape corresponding to the cam lift onto the workpiece W and process it 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 concentrically fixed to the main shaft 32 and rotates together with the main shaft, and a predetermined copying cam contour surface 23a is formed on the end surface of the bell cam 23 on the workpiece W side.
A cam follower roller 24 rotatably supported on a pin 25 fixed diametrically perpendicular to the shaft axis at the left end of the shaft 26 in the figure is pressed against the copying cam contour surface 23a by a pressing means (not shown). It is biased.

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

The cam follower roller 24 at the end of the shaft 26 is pushed to the left in the figure while being guided by the guide part in an integrated state with the shaft 26, sleeve 30, tool rest 27, and piston 29, 28, and as a result, the cam follower roller 24 is pushed to the left in the figure along with the main shaft. The bell cam 23 contacts the cam contour surface 23a of the rotating bell cam 23, 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 with respect to the shaft 26.

Therefore, the cutting tool 29 fixed to the tool rest 27 is
The cutting tool 29 gradually moves leftward from the dotted chain line position 29' to the same 2r position, and then advances to the position shown by the solid line, and then moves to the main shaft 32.
It comes into contact with the workpiece W which is rotationally driven by the tape running surface 1, and starts turning the tape running surface 1.

Next, the tape lead surface 2 is formed by copying the bell cam 23.
This section explains turning. As a result of the above, the cutting tool 29 which is in contact with the tape running surface 1 is completely retracted together with the tool rest 27 upward (in the direction of the arrow 2) in the radial direction (cutting direction) of the work W by the operation of a drive means (not shown). After letting
The sleeve 30 is moved to the right in the figure relative to the shaft 26, and the drive means moves the sleeve 30, the shaft 26, the cam follower roller 24, and the tool post in the opposite direction to the retraction movement, that is, downward in the radial direction of the workpiece W. 27 as a whole, the tape lead surface turning tool 28 is brought into contact with the tape lead surface 2 of the workpiece W, and the tape lead surface 2 is turned by following the cam contour surface 23a.

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

That is, Figures 3 (B) and 3) are developed views of the tape running surface 1 and tape lead surface 2 of the fixed lower drum, respectively. In the same figure, θ is related to a drum for an 8 m tape, for example, which is compatible with a VTR with a digital audio recording function, or a lightweight, compact VTR. IN is a tape inlet; OUT
is the tape exit, and L is the lift slip of the tape lead surface 2 (that is, the same as the lift amount of the bell cam contour surface 23a). a1+at:bt+bx respectively indicate a straight part and a relief part of the lead surface corresponding to the angle of winding around the drum. As mentioned above, as can be seen from the comparison of figures (4) and (2), the lead shapes (wrapping angle, lead angle, cam lift C, etc.) differ depending on the drum type, so it is natural that the same Copying is not possible with a bell cam, and depending on the type of drum, the copying cam may need to be replaced.

For any type of drum, the accuracy required for lead linearity is high, within 1 to 2 μm, so the cam used must be removed from the copying device and replaced with a cam with a different lead shape. When this is not possible, the accuracy of the lead linearity deteriorates depending on the conditions of the cam installation, and it is necessary to correct the cam by re-lapping the cam to maintain the accuracy within the range of 1 to 2 .mu.m.

In this case, in order to ensure the predetermined accuracy through the above-mentioned lapping, it is necessary to first turn the workpiece W, measure its lead, and repeat the necessary re-lapping several times to get closer to the predetermined accuracy. Therefore, this work required 1 to 2 days, consumed many test blanks, and required a large amount of man-hours and material costs.

As mentioned above, the downtime required to replace the copying cam is large, so at production sites, drum processing machines are not designed specifically for each type of drum. Because we are unable to respond,
There are five problems in that each dedicated processing machine has many idle periods when it is not processing, which deteriorates operating efficiency and ultimately increases costs.

〔the purpose〕

The present invention has been made in view of the problems of the conventional examples as described above, and in addition to eliminating the above-mentioned drawbacks, it is also possible to process fixed lower drums of multiple models having different lead shapes relatively easily and with high precision. The purpose is to increase production flexibility by providing a tape drum processing mounting system.

〔Example〕

The present invention will be explained below based on examples.

FIG. 4 is a cutaway side (partially cross-sectional) view of the main part of the lower drum processing device to which the bell cam 23 having a plurality of different lead-shaped cam surfaces 23a, 23b according to the present invention is attached, and FIG. The same or equivalent components are indicated by the same reference numerals. Furthermore, the order of the cutting process for the tape running surface 1 and tape lead surface of each work drum W has already been explained in the section of the prior art, so a redundant explanation will be omitted.

Next, an explanation will be given of the operation when converting the lower drum workpiece W corresponding to the lead-shaped cam surface 23a to the lower drum workpiece corresponding to the different lead-shaped large cam surface 23b.

First, the tool rest 27 is replaced/set so that the tape running surface turning tool 29 and the tape lead surface turning tool 28 can be processed on the work drum, and the tool rest 27, shaft 26, etc. are arranged on it. Move the unillustrated X-axis direction moving table (with the X-axis perpendicular to the drawing) in the two directions shown by the arrows (upward in the drawing) to find a lead-shaped cam surface 23b that is different from the lead-shaped cam surface 23a used last time. , the cam follower roller 24 is brought into contact with the cam follower roller 24, and the same processing steps as described above are performed.

FIG. 5 is a cross-sectional view showing the configuration of the separate copying cam having two P lead shapes used in the above embodiment and attached to the main shaft. A cam body having a lead-shaped cam surface 23a can be housed inside a separate cam body having a different lead-shaped cam surface 23b, and the outer diameter of the cam body 23a (the same reference numeral as the cam surface is substituted. The same applies hereinafter) can be accommodated. Long or large diameter hole 44
The bottom surface of the cam body 23a is brought into contact with the top surface of the recessed part of the cam body 23b by fitting both cam bodies at the pilot part 23C, and the integrated two cam bodies are connected to the main shaft of rotation. 32 (4th
The bottom part of the integral cam body is fitted to the thrust surface 46 of the main shaft using the bolt hole 41 and a bolt (not shown). Tighten and fix.

The space of the recessed portion 44 between the cam bodies 23a and 23b is maintained at an appropriate distance so that the shaft 26 (FIG. 4) that supports the cam roller follower 24 does not come into contact with it.

Furthermore, two cam bodies 23a, 2 having different lead shapes are provided.
In terms of rotational mass balance, it is desirable that the respective maximum cam lift portions of the two cams 3b be arranged diametrically opposite to each other when viewed from the top surface of the cam. In addition, when multiple cam bodies are attached to the main shaft, the load on the main shaft increases, so it is desirable to reduce the weight of each cam body by reducing the thickness of the cross section as much as possible. Also, the main shaft of both cam bodies Instead of using a common bolt and tightening and fixing at the same time as in the example above, both cam bodies are connected in advance with bolts, etc., and the integrated cam body is attached to the main shaft using another bolt. May be installed.

FIG. 6 shows a plurality of different lead-shaped cam bodies 23a.

23b is a cross-sectional view showing an embodiment of the copying cam body 47 integrally formed with the cam mounting portion 45 and the integral cam body 47. They are fitted together at the portion 40 and tightened and fixed at the bolt hole 41 with a bolt (not shown). The mutual arrangement relationship of both lead shapes with respect to the rotational mass balance of the integrally formed cam body, and considerations for reducing the weight of the cross section of the cam body to prevent an increase in the main shaft load, etc., are shown in Fig. 5 of the separate body shape. The case is exactly the same.

The embodiments shown in FIGS. 4 to 6 above are cases in which two cam surfaces have two different lead shapes.

However, the number of cam surfaces is not limited to two, and it goes without saying that the present invention can be applied to two or more cam surfaces in practice.
Although we have explained the processing example of the fixed lower drum for tape guide for helical scan of R, it is not limited to this, but can be applied to digital audio tape recorders, etc.
A similar configuration can be applied to drum processing for devices that perform recording, recording, playback, etc.

〔effect〕

As explained above, according to the present invention, it is possible to process tape drums with different lead shapes without replacing the copying cam. This eliminates the need to consume drums, and allows each drum with a different lead shape to be processed with high precision and at low cost.
At the same time, it has become possible to improve the operating rate of the lead processing machine and increase production flexibility.

[Brief explanation of drawings]

Fig. 1 is a side view of the essential parts of an example of a videotape drum assembly, Fig. 2 is a side view of the main parts of a conventional fixed lower drum processing device, Fig. 3 (2), @ is the fixed lower drum FIG. 4 is a side view of the main part of the lower drum processing device according to the present invention, and FIGS. 5 and 6 are two examples of developed views of the tape running surface and tape lead surface of the present invention, respectively. The attachment of the body shape and the integral shape to the main shaft is a sectional view showing the configuration. W・・・・・−・Fixed lower drum (work) 1...
...Tape running surface 2 ...Tape lead surface 23 ... Copying bell cams 23a, 23b - ... Different lead shape cam surface 2
4...Cam follower roller 32...
... Rotating main shaft 45 ... Main shaft cam mounting part 47 ...
...Integrated cam body Fig. 1 II 3 Fig. (A) 1s4 Fig.

Claims (1)

[Claims] A processing device that has a copying cam attached to a rotating main shaft and uses the cam to copy a tape running surface and a tape lead surface of a tape drum attached to the main shaft, wherein the cam has a plurality of lead shapes. A tape drum processing device characterized by: