JPH05282632A - Formation of round shape - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide an R forming method capable of forming an edge portion of a window portion provided on an upper drum of a magnetic recording / reproducing apparatus using a rotary head in an accurate and stable R shape. .. [Structure] In the upper drum 1, a positioning shaft 9 provided in a holding jig 7 is inserted into a positioning hole 3 provided in the upper drum 1, and a holding disc 11 and a fixing screw 12 hold the upper drum 1 in a holding jig. Fix to 7. The punch 6 is fixed on the movable side of the pressing device, and the holding jig 7 is fixed on the table of the pressing device. The punch 6 is pressure-bonded to the window portion 2 of the upper drum 1 by a pressing device, and the R shape 4 previously formed on the punch 6 is transferred to the edge portion 14 of the window portion 2 of the upper drum 1. According to this method, the edge portion of the window portion provided on the upper drum can be R-formed with a precise and stable shape.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a window mounted on a rotary head type recording / reproducing device such as a VTR or a DAT for projecting a magnetic head from a rotary cylinder. The present invention relates to an R forming method for stably forming an R shape on an edge portion of a portion. 2. Description of the Related Art Conventionally, an upper drum, which constitutes a recording portion of a recording / reproducing apparatus using a rotary head such as a VTR / DAT, is provided with a window portion for projecting a magnetic head from the rotary drum. There is. R is formed at the edge of this window so as not to damage the magnetic tape. This R
As a method of forming, the lapping method in which the lapping tape having the abrasive grains adhered to the sheet is pressed against the edge portion of the window portion to perform polishing, or the abrasive grains are applied to the outer peripheral surface of the rotating disc-shaped cloth. There is a buff method in which the edge portion of the window portion is pressed against a cloth coated with abrasive grains to polish the cloth. In such conventional lapping and buffing R forming methods, it is difficult to automate, the R shape is not stable, R forming takes a long time, and abrasive grains are not formed. There were problems such as the deterioration of the environment due to falling off and the embedding of abrasive grains in the drum. The present invention solves such a problem, and an object of the present invention is to provide an R forming method capable of forming an edge portion of a window portion provided on an upper drum with a precise and stable shape. It is what In order to solve this problem, the present invention relates to an upper drum constituting a rotary cylinder unit used in a recording / reproducing apparatus using a magnetic tape, in which a magnetic head is connected to a rotary cylinder. A method of forming R on an edge portion of a window portion provided for projecting, in which a press device is provided with a punch having an R shape and a holding jig for holding the upper drum, and the upper drum is fixed to the holding jig. The R-shaped punch fixed to the press machine is crimped to the window part of the upper drum by the press machine, and
The punched R shape is transferred to the window portion of the upper drum. According to this method, since the R shape is formed by the transfer method, the edge portion of the window portion provided on the upper drum used in the rotary head type magnetic recording / reproducing apparatus is processed. R shape can be formed with excellent accuracy and stable shape with good reproducibility. Further, since the R processing is performed by a transfer method using a press, automation is facilitated and mass productivity is improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An R processing method according to an embodiment of the present invention will be described below with reference to the drawings. 1 (a) and 1 (b), R is obtained by the method of this embodiment.
FIG. 4 shows the configuration of the upper drum to be processed, and the state of the punch and the holding jig when forming the R on the rotary cylinder. As shown in FIGS. 1A, 1B and 4, the upper drum 1 includes a positioning shaft 9 provided on a holding jig 7.
Is inserted into the positioning hole 3 provided in the upper drum 1, and the upper drum 1 is fixed to the holding jig 7 with the holding disk 11 and the fixing screw 12. 2 (a) and 2 (b) show the structure of the punch used for forming the R of the present invention, and FIGS. 3 (a) to 3 (c) show the structure of the rotary cylinder holding jig used for forming the R of this embodiment. Indicates.
As shown in FIGS. 2A and 2B and FIGS. 3A to 3C, the punch 6 is fixed to the movable side of the press device, and the holding jig 7 is fixed on the table of the press device. .. The method of fixing the punch 6 and the holding jig 7 is as follows:
Is inserted into the holding jig 7, a square hole 8 having the same shape as the tip shape 5 of the punch 6 is provided in the holding jig 7, and the square tip portion 5 of the punch 6 is provided in the holding jig 7. Square hole 8
The punch 6 and the holding jig 7 are fixed to the press device at a position to be inserted into the press device. When the upper drum 1 is fixed to the holding jig 7, it is confirmed that the square hole 8 formed in the holding jig 7 and the window 2 of the upper drum 1 are aligned with each other. FIG. 5 shows the shape of the upper drum window C portion of FIG. 1 (a) which is R-formed by the method of the present invention. The punch 6 is attached to the press device, and the punch 6 is pressed against the window 2 of the upper drum 1 by a press. The R shape 4 formed in advance on the punch 6 is transferred to the window portion 2 of the upper drum 1 to the edge portion 14 with high precision as shown in FIG. According to this method, the edge portion of the window portion provided on the upper drum can be R-shaped with a precise and stable shape. As is apparent from the description of the above embodiment, according to the present invention, it is possible to form the R edge portion of the window portion with excellent processing accuracy and a stable shape. Further, since this method can form R with stable quality and good reproducibility, it is excellent in productivity as a mass production method, and it is possible to mass produce members having R with high accuracy. Further, when the R-processed upper drum according to the present invention was used for a VTR, the occurrence of scratches on the video tape due to the friction of the upper drum was eliminated, and good tape running performance was obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a front view of a rotary cylinder formed by a method according to an embodiment of the present invention, FIG. 1 (b) is a side view thereof, and FIG. The front view (b) of the punch used for forming is the same side view. [FIG. 3] (a) The front view of the rotary cylinder holding jig used for forming the same (b) is the same side view (c) The bottom view FIG. 4 is a side view showing a state of a punch and a holding jig when forming R on the rotary cylinder; FIG. 5 (a) is the same FIG. 1; 5A is a sectional view taken along the line BB in FIG. 5A. [Description of symbols] 1 upper drum 2 window 3 positioning hole 4 R shape 5 square tip 6 punch 7 Holding jig 8 Square hole 9 Positioning shaft 10 Female screw 11 Holding disk 12 Fixing screw 13 Punch sliding direction 14 Window R forming shape

Claims (1)

What is claimed is: 1. An upper drum, which constitutes a rotary cylinder unit used for a recording / reproducing apparatus using a magnetic tape, has an edge portion of a window portion provided for projecting a magnetic head from the rotary cylinder. A method of forming R on a press device, wherein a holding jig for holding a punch having an R shape and an upper drum is attached to a pressing device, the upper drum is fixed to the holding jig, and the holding jig is fixed to the pressing device. An R forming method in which a punch having an R shape is pressure-bonded to the window portion of the upper drum by the pressing device and the R shape of the punch having the R shape is transferred to the window portion of the upper drum.