JPH0262721A - Production of metallic disk substrate for lining magnetic sheet - Google Patents

Abstract

PURPOSE:To shorten the time for working and to improve productivity by holding a metallic blank material in place between two dies formed with annular recesses corresponding to annular projecting edges and annular projecting parts corresponding to annular hollow grooves on the pressurizing surfaces in a metallic mold for regulating the spread limit of the material in the diametral direction thereof and coining the material. CONSTITUTION:The upper and lower dies 11, 12 are formed with the annular projecting parts 15 and the annular recesses 16, 17 in the inner and outer peripheral parts on the respective pressurizing surfaces and is projected with a mandrel 14 at the center of the lower die 11. A recess 18 to be fitted with a head part of the mandrel 14 is formed on the upper die 12. The aluminum blank material 10 is imposed on the lower die 11 and the upper die 12 is lowered in this state to press the aluminum blank material 10 by the pressurizing force until the material spreads fully in the ring 13, thereby coining the material. As a result, the pressurizing surfaces of the dies 11, 12 are transferred to the front and rear surfaces of the material 10 and the metallic disk substrate 1 for lining a flexible magnetic sheet 2 is produced. The time for working is shortened in this way and the improved productivity and the reduced cost are attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a metal disk substrate in a magnetic disk constructed by pasting flexible magnetic sheets on both sides of the metal disk substrate.

[Conventional technology and its issues]

Magnetic disks used in external storage devices for electronic computers usually have a structure in which the surface of an aluminum disk substrate is coated with a magnetic material. In response, a magnetic disk as shown in Figure 2 has recently been proposed (
(Japanese Unexamined Patent Publication No. 62-121930).

This M1 disk has two surfaces on both sides of the metal disk substrate 1.
A floppy disk or a flexible magnetic sheet (herein referred to as a flexible magnetic sheet) 2 having a magnetic layer on one side is pasted with the magnetic layer facing outward. The metal disk substrate l has annular convex edges 3 and 4 on the inner and outer circumferences of both sides, to which the inner and outer circumferences of the flexible magnetic sheet 2 are attached.
4 is an annular groove 5. Therefore, in this magnetic disk, a gap 6 is formed between the metal disk substrate 1 and the flexible magnetic sheet 2.

Conventionally, in order to manufacture a metal disk substrate for use in this type of magnetic disk, first a disk-shaped blank with a hole in the center is punched out of a metal plate, then multiple sheets are stacked and pressure annealed to form the blank. After improving the flatness of the material, it is cut or ground to a predetermined size.

However, with this method, there are problems in that cutting or grinding takes time, productivity is low, and processing costs are high.

[Means for solving problems and their effects]

The present invention provides a method for manufacturing a metal disk substrate with a magnetic sheet attached thereto, which solves the above-mentioned problems. In a method for manufacturing a metal disk substrate, the metal blank has an annular convex edge to which the outer circumference is attached, and an annular concave groove is formed between the two annular convex edges. The coining process is performed by sandwiching it between two dies in which a pressurizing surface is formed with an annular recess corresponding to the annular convex edge and an annular convex edge corresponding to the annular groove. It is something to do.

In this method, the annular convex edge and annular groove of the metal disk substrate are formed by coining, so the processing time is extremely short (
It is possible to significantly improve productivity.

The material of the metal disk substrate is generally aluminum (including alloys), but other non-magnetic metals such as copper and titanium can also be used.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, 5086-0 material (AI-Mg alloy, tensile strength σ
m -27Kg/I"), punched from a plate material with a thickness of 1.51mm, with an outer diameter of 94.5'mm and an inner diameter of 25.1mm.
An aluminum blank material in the shape of a disc with a hole of mm in diameter was manufactured.

On the other hand, the die unit for coining this is a pair of upper and lower dies 11 with pressing surfaces facing each other, as shown in Figure 1.
12 and the ring placed around it (outer mold) 1
3 and a core metal (inner peripheral mold) 14 located at the center. The upper and lower dies 11 and 12 each have an annular convex edge 15 and annular concave portions 16 and 17 on the inner and outer circumferences thereof, respectively, on the pressurizing surfaces. Annular convex edge 1
5 and the annular recesses 16 and 17 are 0.2 mm in height,
The width W of the annular recesses 16 and 17 was 2.0 mm. In addition, the pressure surfaces of dies 11 and 12 have a surface roughness Rmax = 0.2
It was finished to 0 μ-. A mandrel 14 is projected from the center of the lower die 11, and a recess I8 into which the head of the mandrel 14 fits is formed in the upper die 12. The inner diameter of the ring 13 is 95.0+u+, and the outer diameter of the core metal 14 is 25.0m.
It was set as m.

Next, after applying a lubricant (G6316 manufactured by Nippon Craft Oil Co., Ltd.) to both sides of the aluminum blank at a rate of 3 g/m,
As shown in Figure-1, the aluminum blank material 10 is cut into the lower die 1.
It was placed on 1. In this state, lower the upper die 12,
Aluminum blank material 10 with a pressure of 105g/lan''
was pressed until it was fully spread inside the ring 13, and the coining process was performed.

As a result, dies 11 are placed on the upper and lower surfaces of the aluminum blank material 10.
・12 pressure surfaces are transferred, and a width of 2.5 mm is applied to the inner and outer peripheries of both sides. It was possible to obtain a metal disk substrate having an annular convex edge of Oe++w and an annular groove with a depth of 0.21 between both annular convex edges. Surface roughness Rma of this metal disk substrate
x was 0.25μ.

In addition, according to various experiments, the pressurizing force P (Kg/
+m”) is the tensile strength σ of the aluminum blank material.

(Kg/mm") to 5 times or less was effective in reducing waviness and warping of the obtained metal disk substrate.

〔Effect of the invention〕

As explained above, according to the present invention, a metal disk substrate for attaching a flexible magnetic sheet can be manufactured by coining using a press, which dramatically improves productivity compared to conventional cutting and grinding processes. Cost reduction can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a method for manufacturing a metal disk substrate for attaching a flexible magnetic sheet according to an embodiment of the present invention;
FIG. 2 is a sectional view of a magnetic disk in which a flexible magnetic sheet is attached to a metal disk substrate. 10 aluminum blank material, 11: lower die, 12: upper die, 13: ring, 14: mandrel, 15: annular convex edge, 1
6.17: Annular recess. Figure-1 Figure-2

Claims (1)

[Claims] 1. Manufacture of a metal disk substrate having an annular convex edge to which the inner and outer circumferential parts of a flexible magnetic sheet are pasted on the inner and outer circumferences of both sides, and an annular groove between both annular convex edges. In the method, a metal blank material is placed in a mold that limits the spread of the material in the radial direction, and an annular concave portion corresponding to the annular convex edge and an annular convex portion corresponding to the annular concave groove are formed on the pressurizing surface. A method for manufacturing a metal disk substrate for attaching a magnetic sheet, characterized by performing a coining process by inserting the substrate between two formed dies.