JPH06182819A - Adjustment of weld position in molding of diskette half - Google Patents

Abstract

PURPOSE:To easily and certainly control a weld position at the time of the molding of the diskette half of a microfloppy disk. CONSTITUTION:A mold has two direct gates 41, 42 on one side of one cavity 23. At the beginning, the diameter of the gates 41, 42 is made smaller than the thickness of a diskette half and the weld line generated in the molded diskette half is investigated. The gates 41, 42 near to the weld line are cut to be made large in diameter. By this method, a weld position approaches the other gates 41, 42. This operation is repeated so that the weld position coincides with a gas venting slit. When the diameter of the gates 41, 42 becomes larger than the thickness of the diskette half, the control of the weld position becomes difficult.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weld position adjusting method for forming a diskette half such as a micro floppy disk.

[0002]

2. Description of the Related Art Micro floppy disk (hereinafter referred to as M
(FD) is a disk-shaped record carrier rotatably accommodated in a diskette formed by combining a thin upper diskette half and a lower diskette half. All diskette halves are resin molded products. Figure 4
And FIG. 5 shows the upper diskette half 1. The upper diskette half 1 has a substantially rectangular flat plate shape, and the frame wall 2 is formed in the peripheral portion. On the inner surface of the upper diskette half 1, a shallow circular concave record carrier accommodating portion 3 is formed. A plurality of arc-shaped disc guide ribs 4 are formed on the peripheral edge of the record carrier storage portion 3, and an annular hub guide rib 5 is formed on the center of the record carrier storage portion 3. There is. Along with this, in the front center of the upper diskette half 1,
An opening window 6 for introducing the head is formed. Further, a plurality of lifter receiving ribs 7 are provided on one side of the record carrier storage portion 3.
Are formed. Further, on the outer surface side of the upper diskette half 1, a shutter incorporating portion 8 is formed in the front portion, and a label surface 9 is formed in the rear portion in a concave shape.
Further, among the four corner portions 11, 12, 13, 14 on the outer side of the record carrier housing portion 3 in the upper diskette half 1, a corner portion 11 on one front side is a spring housing portion for urging the shutter. 15 is formed, and a light protector built-in portion 16 is formed in the corner portion 13 on one side of the rear portion. In addition, the wall thickness of the normal upper diskette half 1 is about 0.7 mm in the record carrier storage portion 3, and the corner portion 1
It is 1.0 to 1.2 mm for 1, 12, 13, and 14.

Next, an example of a conventional molding die for molding the upper diskette half 1 will be described with reference to FIGS. 2 to 3 showing the outline thereof. 21 is a fixed type,
Reference numeral 22 denotes a movable mold, and these fixed mold 21 and movable mold 22 as mold members are opened and closed in the vertical direction in the drawing to form a cavity 23 in the shape of the upper diskette half 1 inside during mold clamping. In particular, the fixed mold 21 forms the outer surface of the upper diskette half 1, and the movable mold 22 forms the inner surface of the upper diskette half 1. In the fixed mold 21, two resin passages 24 and 25 are formed for one cavity 23. These resin passages 24, 25
Respectively have spears 26 and 27 built therein, and the tips thereof are opened as direct gates 28 and 29 into the cavity 23 in the thickness direction of the upper diskette half 1. Both gates 28 and 29 are open to positions corresponding to both front corners 11 and 12 outside the record carrier storage 3. In addition, the movable die 22 is provided with a plurality of degassing inserts 30, 31.
Is fixed, and thereby, gas vent slits 32 and 33 are formed which are opened to positions corresponding to the rear portion and the central portion of the record carrier storage portion 3 in the cavity 23.
In the conventional mold, the upper diskette half 1 may be thin, and for example, the thickness t is 1.
The diameter r of the gates 28 and 29 is 1.3 mm, while it is 2 mm, which is generally the thickness t of the upper diskette half 1.
The diameter r of the gates 28 and 29 was larger than that.

At the time of molding, the molten resin flows from the gates 28 and 29 into one cavity 23 in the mold clamping state. The resin injected from both gates 27 flows backward as shown by a chain line in FIGS. 3 and 4, and finally fills the entire cavity 23. The weld position of the resin injected from both gates 27 is substantially on the left and right center lines of the cavity 23, and the gas chased by the flowing resin escapes from the cavity 23 via the gas vent slit 31. Note that 3
6 and 37 are gate traces on the molded upper diskette 1, and 38 and 39 are degassing traces. The gate marks 36 and 37 appear on the outer surface of the upper diskette 1, but are normally hidden by the shutter.

The molding die for the lower diskette half is also the same.

[0006]

By the way, the gate 28,
The reason for setting 29 as two points is to improve resin filling and improve flatness of the molded product, but both gates 28 and 29 are used.
The position of the weld of the resin from and the degassing slits 32 and 33 must coincide. If they do not match, degassing may not be performed smoothly, inconveniences such as gas burning may occur, the moldability may deteriorate, and the quality of the molded product may become unstable. However, the diskette half 1 does not have a symmetrical shape on the left and right, and therefore, as shown in FIGS.
As shown by the two-dot chain line a, a weld line may be formed at a position outside the gas vent slits 32 and 33. On the other hand, a possible method of adjusting the weld position is to selectively subject the gates 28 and 29 to cutting or the like in accordance with the weld line generated in the actual molded product, It is to adjust the diameter r. However, if the diameter r of the gates 28 and 29 is larger than the wall thickness t of the upper diskette half 1 from the beginning like the above-mentioned conventional die, even if the diameter r of the gates 28 and 29 is changed, the weld position is not so much. does not change.

An object of the present invention is to solve such a problem, and an object thereof is to easily and surely adjust the weld position when forming a diskette half such as a micro floppy disk.

[0008]

In order to achieve the above object, a method for adjusting a weld position in molding a diskette half according to the present invention comprises a plurality of mold members that can be opened and closed.
A cavity with the shape of a diskette half is formed between the mold members when the mold is clamped, and a mold having a plurality of gates opened in the thickness direction of the diskette half in the mold member is used. Is smaller than the wall thickness of the diskette half, and the gate is selectively processed to increase its diameter, whereby the weld position in the diskette half to be molded is adjusted.

[0009]

In the method for adjusting the weld position in the molding of the diskette half of the present invention, after the resin is filled into the cavities from a plurality of gates to mold the diskette half,
Examine the weld line generated on this diskette half, and depending on the position of this weld line, selectively cut the gate to process it, and increase the diameter of this gate to improve the weld position in the subsequent molding. Adjust. In other words, if you increase the diameter of a gate,
The weld location is farther from the gate. When molding the diskette half, if the diameter of the gate is larger than the wall thickness of the diskette half, the weld position does not change much even if the diameter of some gates is increased, so to adjust the weld position, Initially, it is necessary to make the diameter of the gate smaller than the wall thickness of the diskette half.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a mold for molding the upper diskette half 1 of the micro floppy disk. The mold of this embodiment is the mold described in FIGS. 2 and 3 described above.
Since it has almost the same structure as the mold shown in (1), the corresponding parts are designated by the same reference numerals and the description thereof is omitted. In the mold of this embodiment, the initial diameter R of the gates 41, 42 is made smaller than the wall thickness t of the upper diskette half 1. That is, the wall thickness t of the upper diskette half 1 is 1.2 mm, while the diameter R of the gates 41 and 42 is 0.95 mm.

At the time of molding, both gates 41 and 42 are kept in the mold clamped state.
The cavity 23 is filled with the molten resin, and the upper diskette half 1 is molded. Then, the weld line generated on the molded upper diskette half 1 is examined, and the gates 41 and 42 are selectively selected according to the position of the weld line.
The gates 41, 42 are enlarged in diameter by subjecting them to cutting or the like. In fact, the weld line is a gas vent slit
If it is on the left side of 32 and 33, the left gate 41
Increase the diameter a little. If it is off to the right, increase the diameter of the left gate 42 slightly. One gate 41, 42
If the diameter is increased, the weld position is located farther from the gates 41 and 42 whose diameters are increased in the subsequent molding. In this manner, the molding and the processing of the gates 41 and 42 are repeated so that the weld position coincides with the gas vent slits 32 and 33. Weld position is a gas vent slit
If they match 32 and 33, degassing is performed satisfactorily, molding defects due to degassing defects can be prevented, moldability is improved, and the quality of the molded product is stabilized. Of course, the purpose of adjusting the weld position is not limited to degassing.

In the MFD diskette half molding, if the diameter of the gate is larger than the wall thickness of the diskette half, the weld position does not change much even if the diameter of only one gate is increased. It becomes difficult to adjust the weld position by adjusting the diameter. On the other hand, as in the present embodiment, the initial diameter R of the gates 41 and 42 is R.
If the thickness is smaller than the wall thickness t of the diskette half 1, the weld position can be adjusted easily and reliably. However, even in the case of the present embodiment, as a result of the adjustment, the diameters of the gates 41 and 42 may eventually become larger than the wall thickness t of the diskette half 1.

The present invention is not limited to the above embodiment, and various modifications can be made. For example,
The diameter R of the gates 41 and 42 is not limited to 0.95 mm in the above embodiment, but can be reduced to about 0.85 mm if the thickness t of the upper diskette half 1 is 1.2 mm. However, gate 4
If the diameter R of 1, 42 is too small, the pressure loss of the resin increases due to the throttling of the gates 41, 42, which is not preferable.
Further, in the above embodiment, the upper diskette half 1 is described as an example, but the present invention can be applied to the molding of the lower diskette half. Further, although the mold of the above-described embodiment is of the spear type, it may be of the valve gate type or may be of another type.

[0014]

According to the present invention, a die having a plurality of gates opened in the thickness direction of the diskette half is used in the cavity, and the diameter of the gate is initially made smaller than the wall thickness of the diskette half. Since the weld position in the diskette half to be molded is adjusted by selectively subjecting the gate to a process of increasing its diameter, the weld position can be easily and surely adjusted when the diskette half such as a micro floppy disk is molded.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a diskette half molding die according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example of a conventional diskette half molding die, which corresponds to a cross section taken along the line AA of FIG.

FIG. 3 is a sectional view of the same, corresponding to the section taken along the line BB of FIG. 4.

FIG. 4 is a plan view of the outside of the upper diskette half of the micro floppy disk.

FIG. 5 is a bottom view of the inner side of the same.

[Explanation of symbols]

 1 Diskette half 21 Fixed mold (mold member) 22 Movable mold (mold member) 23 Cavity 41 Gate 42 Gate

Claims (1)

[Claims] 1. A plurality of mold members that can be opened and closed are provided, and a cavity in the shape of a diskette half is formed between the mold members at the time of mold clamping, and a plurality of cavities opened in the thickness direction of the diskette half are formed in this cavity. A diskette to be formed by using a die having a gate as a die member, initially making the diameter of the gate smaller than the thickness of the diskette half, and selectively subjecting the gate to a process of increasing the diameter. A method for adjusting a weld position in molding a diskette half, which comprises adjusting a weld position in the half.