JP3084697B2 - Weld position adjustment method in molding diskette half - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Micro floppy disks (hereinafter referred to as M
FD) comprises a disk-shaped record carrier rotatably housed in a diskette formed by combining a thin upper diskette half and a lower diskette half. Each diskette half is a resin molded product. FIG.
FIG. 5 shows the upper diskette half 1, which is substantially in the shape of a rectangular flat plate, and has a frame wall 2 formed at the periphery. On the inner surface of the upper diskette half 1, a shallow circular concave recording carrier storage section 3 is formed. A plurality of arc-shaped disc guide ribs 4 are formed on the periphery of the record carrier housing 3, and an annular hub guide rib 5 is formed on the center of the record carrier housing 3. I have. At the same time, in the front center of the upper diskette half 1,
An opening window 6 for introducing a head is formed. A plurality of lifter receiving ribs 7 are provided on one side of the
Are formed. Further, on the outer surface side of the upper diskette half 1, a shutter assembling portion 8 is formed at a front portion, and a label surface 9 is formed at a rear portion thereof in a concave shape.
A spring storage section for urging a shutter is provided in one of the four corner sections 11, 12, 13, 14 outside the record carrier storage section 3 in the upper diskette half 1 on the front side. 15 is formed, and a write protector built-in portion 16 is formed in a corner portion 13 on one rear side. Incidentally, the thickness of the normal upper diskette half 1 is about 0.7 mm in the record carrier storage section 3, and the corner section 1
For 1, 12, 13, and 14, it is 1.0 to 1.2 mm.

Next, an example of a conventional molding die for molding the upper diskette half 1 will be described with reference to FIGS. 21 is fixed type,
Reference numeral 22 denotes a movable die. The fixed die 21 and the movable die 22 as mold members are opened and closed in the vertical direction in the drawing, and form a cavity 23 in the shape of the upper diskette half 1 when the die is clamped. In particular, the fixed die 21 forms the outer surface of the upper diskette half 1, and the movable die 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
Have built-in spears 26 and 27, respectively, and the front ends are opened as direct gates 28 and 29 to the cavity 23 in the thickness direction of the upper diskette half 1. The gates 28 and 29 are open to positions corresponding to the front corners 11 and 12 outside the record carrier housing 3. In addition, the movable mold 22 has a plurality of gas vents 30, 31.
Are fixed, whereby gas vent slits 32 and 33 are formed, which are opened to positions corresponding to the rear and center portions of the record carrier housing 3 in the cavity 23.
In the conventional mold, the upper diskette half 1 may be thin, for example, the thickness t is 1.
While the diameter r of the gates 28 and 29 is 1.3 mm, the thickness t of the upper diskette half 1 is generally 2 mm.
The diameter r of the gates 28 and 29 was larger than that of the gates 28 and 29.

During molding, molten resin flows into one cavity 23 from gates 28 and 29 in a mold-clamped state. The resin injected from both gates 27 flows backward as shown by the chain line in FIGS. 3 and 4, and is finally filled in the entire cavity 23. Then, 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 through the vent slit 31. Note that 3
Reference numerals 6 and 37 denote gate traces on the upper diskette 1 formed, and 38 and 39 degas traces. The gate traces 36 and 37 appear on the outer surface of the upper diskette 1, but are always hidden by the shutter.

The same applies to the lower diskette half molding die.

[0006]

The gate 28,
The reason why the two points 29 are used is to improve the filling of the resin and improve the flatness of the molded product.
The welding position of the resin from the opening must match the vent slits 32, 33. If they do not match, degassing will not be performed smoothly, causing inconveniences such as gas burning, resulting in reduced moldability and unstable molded product quality. However, the diskette half 1 is not symmetrical on the left and right, and so
As shown by a two-dot chain line a, a weld line may be formed at a position deviated from the gas vent slits 32, 33. On the other hand, as a method of adjusting the weld position, a method such as cutting is selectively applied to the gates 28 and 29 in accordance with a weld line generated in an actual molded product, and Adjusting the diameter r. However, if the diameter r of the gates 28 and 29 is larger than the thickness t of the upper diskette half 1 from the beginning as in the conventional mold described above, the weld position is too small even if the diameter r of the gates 28 and 29 is changed. does not change.

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

[0008]

According to the present invention, there is provided a method for adjusting a weld position in forming a diskette half, comprising a plurality of mold members which can be opened and closed to achieve the above object.
At the time of mold clamping, a disk-shaped half-shaped cavity is formed between the die members, and a die having a plurality of gates opened in the thickness direction of the diskette half in the cavity is used for the die member. Is made smaller than the thickness of the diskette half, and the gate is selectively processed to increase its diameter, thereby adjusting the weld position of the diskette half to be formed.

[0009]

According to the method for adjusting the weld position in molding a diskette half of the present invention, a resin is filled into a cavity from a plurality of gates to form a diskette half.
The weld line generated in the diskette half is examined, and the gate is selectively cut or machined in accordance with the position of the weld line, and the diameter of the gate is increased to thereby determine the weld position in the subsequent molding. Adjust. In other words, if you increase the diameter of a certain gate,
The weld location is further away from the gate. In forming the diskette half, if the diameter of the gate is larger than the thickness of the diskette half, even if the diameter of some gates is increased, the weld position does not change much. Initially, it is necessary to make the diameter of the gate smaller than the thickness of the diskette half.

[0010]

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 same as that shown in FIGS.
Since the structure is almost the same as that of the mold shown in FIG. In the mold of the present embodiment, the initial diameter R of the gates 41 and 42 is smaller than the thickness t of the upper diskette half 1. That is, while the thickness t of the upper diskette half 1 is 1.2 mm, 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 a mold-clamped state.
Then, the cavity 23 is filled with a molten resin, and the upper diskette half 1 is formed. Then, a weld line formed on the formed upper diskette half 1 is examined, and gates 41 and 42 are selectively provided according to the position of the weld line.
The gates 41 and 42 are made larger by performing processing such as cutting. In fact, the weld line is a gas vent slit
If it is off to the left of 32 and 33, the gate 41 on the left
A little larger diameter. If it is off to the right, slightly increase the diameter of the left gate 42. One gate 41, 42
If the diameter is increased, in subsequent molding, the weld position will be a position further away from the gates 41 and 42 whose diameter has been increased. Thus, the molding and the processing of the gates 41 and 42 are repeated so that the weld position coincides with the gas release slits 32 and 33. Weld position is gas vent slit
If the values match 32 and 33, degassing is performed well, and molding defects due to defective gas venting can be prevented, moldability is improved, and the quality of molded products is stabilized. Of course, the purpose of adjusting the weld position is not limited to gas release.

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

Note that the present invention is not limited to the above-described 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 restriction of the gates 41, 42, which is not preferable.
Further, in the above embodiment, the upper diskette half 1 has been described as an example, but the present invention can of course be applied to the formation of the lower diskette half. Further, the mold of the above embodiment is of a spear type, but may be of a valve gate type or of another type.

[0014]

According to the present invention, a mold having a plurality of gates opened to the cavity in the thickness direction of the diskette half is used, and the diameter of the gate is initially smaller than the thickness of the diskette half. Since the weld position of the diskette half to be formed is adjusted by selectively performing processing for increasing the diameter of the gate, the weld position can be easily and reliably adjusted when forming a diskette half such as a micro floppy disk.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a sectional view of a diskette half molding die.

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 line AA of FIG.

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

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

FIG. 5 is a bottom view of the inside 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

Continuation of the front page (56) References JP-A-48-71461 (JP, A) JP-A-3-288609 (JP, A) JP-A-3-43220 (JP, A) JP-A-2-202414 (JP) JP-A-4-53718 (JP, A) JP-A-5-278061 (JP, A) JP-A-55-91150 (JP, U) JP-A-64-36121 (JP, U) 4-52015 (JP, U) Fully open 1986-204714 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/26-45/44 B29C 33/00-33 / 76

Claims (1)

(57) [Claims] 1. A plurality of mold members which are openable and closable, a diskette half-shaped cavity is formed between the mold members at the time of mold clamping, and a plurality of openings are formed in the cavity in the thickness direction of the diskette half. A diskette formed by using a mold having a gate in a mold member, initially setting the diameter of the gate smaller than the thickness of the diskette half, and selectively performing processing to increase the diameter of the gate. A method for adjusting a weld position in forming a diskette half, comprising adjusting a weld position in the half.