JP3370640B2 - Manufacturing method of thin resin plate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for manufacturing thin resin plates such as IC cards, smart media and SD cards.

[0002]

2. Description of the Related Art FIGS. 6 (a) and 6 (b) are a front view and a cross-sectional view of a conventional equal-thickness card, and since the card 101 has a uniform thickness, it is punched or cut from a large-sized resin sheet. It can be easily manufactured by taking out or molding by an injection molding method.

7A and 7B are a front view and a sectional view of a conventional different-thickness type card, and the card 102 has a thickness T1.
This is a different-thickness type card including a portion 103, a portion 104 having a thinner thickness T2, and a portion 105 having a thinner thickness T3.

[0004]

Such a different-thickness type card 102 cannot be manufactured by punching or cutting out from a large-sized resin sheet. Therefore, it is manufactured by the injection molding method, but since the resin does not easily flow in the portion 105 having the thinnest thickness T3, it is necessary to greatly increase the injection pressure.
In addition, defects such as weld marks are likely to occur, resulting in poor yield.

Therefore, an object of the present invention is to provide a method for manufacturing a thin resin plate suitable for manufacturing a card of different thickness.

[0006]

In order to achieve the above object, the first aspect of the present invention is to provide a first core protruding into the cavity after filling the cavity of the mold with the resin, and a second core separated from the cavity after the resin is filled. When the thin resin plate having the thin portion locally is formed by forming the thin portion with the first core and forming the thick portion with the second core, the reduction of the cavity due to the protrusion of the first core is provided. It is characterized in that the volume increase of the cavity due to the retreat of the second core is set to be larger than the volume, and the difference obtained by subtracting the volume decrease from the volume increase is additionally filled from the injector side.

Resin is injected into a cavity having a uniform gap. A thin portion is formed by ejecting the first core after injection. Therefore, the flow of the resin becomes smooth, there is no fear that defects will occur, and it is possible to easily manufacture a good-quality thin resin plate of different thickness.

According to a second aspect of the present invention, there is provided a first core that protrudes into the cavity after the cavity of the mold is filled with the resin, and a second core that is separated from the cavity after the resin is filled. When a thin resin plate locally having a thin portion is formed by forming a thick portion with two cores, the volume increase of the cavity due to the retreat of the second core is made more than the volume reduction of the cavity due to the protrusion of the first core. Is set small and the difference obtained by subtracting the increase volume from the reduction volume is returned to the injector side.

Resin is injected into a cavity having a uniform gap. A thin portion is formed by ejecting the first core after injection. Therefore, the flow of the resin becomes smooth, there is no fear that defects will occur, and it is possible to easily manufacture a good-quality thin resin plate of different thickness.

According to a third aspect of the present invention, the tip of the second core is aligned with the tip of the first core in preparation for the first resin filling. By aligning the tip of the second core with the tip of the first core, the wall of the cavity is flattened to smooth the resin flow.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a principle diagram of an injection molding apparatus for carrying out the method of the present invention.
Is an injection machine 11 for injecting resin, a fixed die 12, a movable die 13, a first core 15 and a second core 16 slidably attached to the movable die 13, and a first core 15 for moving the first core 15. Cylinder 17 and second moving second core 16
And a cylinder 18. The mold clamping machine is omitted.

Here, what is important is that the tip of the first core 15 and the tip of the second core 16 are aligned and aligned with the wall of the cavity of the movable mold 13 so that the wall of the cavity 19 is not provided with irregularities. is there. As a result, the flow of the molten resin after injection can be made smooth and defects such as weld marks can be suppressed.

FIG. 2 is a view for explaining the first operation of FIG.
Press 1 and inject the resin. The resin flows into the cavity 19 via the gate 22 as indicated by the arrow. As described above, since the walls of the cavity 19 are flat, the resin flow is smooth.

FIG. 3 is a view for explaining the second operation of FIG. 1. When the cavity 19 can be filled with a predetermined amount of molten resin, the first cylinder 17 causes the first core 15 to protrude into the cavity 19 (arrow), and is parallel. Then, the second core 16 is retracted (arrow) in the second cylinder 18.

If the first core 15 having the area A1 advances by the stroke S1, the initial volume of the cavity 19 is reduced by (A1 × S1). This (A1 × S1) is called reduced volume Q1. Further, if the second core 16 having the area A2 is retracted by the stroke S2, the initial volume of the cavity 19 is increased by (A2 × S2). This (A2 × S2) is called increased volume Q2.

The present invention is characterized in that the volume increase Q2 is set larger or smaller than the volume decrease Q1, that is, it is intentionally made unequal. The reason for this will be described in detail.

It is known in hydraulic cylinders to take a measure called volume compensation in which the same amount of liquid is released when the pin is inserted into a closed container containing an incompressible liquid. If this technology is applied, the capacity reduction Q1
= It is sufficient to increase the volume Q2. However, A1,
S1 is a dimension that determines the size and thickness of the thinnest portion of the different-thickness type card, A2 and S2 are dimensions that determine the size and thickness of another portion, and these dimensions are determined from the shape of the card. It is decided and cannot be decided from volume compensation.

Therefore, in the present invention, by setting the increase volume Q2 larger or smaller than the reduction capacity Q1,
This is to carry out volume compensation while keeping the dimensions required from the card shape.

The control flow when the volume reduction Q1 <volume increase Q2 is described with reference to FIG. 4, and the control flow when volume reduction Q1> volume increase Q2 is described with reference to FIG.

FIG. 4 is a first control flow chart according to the method of the present invention, where STXX indicates a step number. ST01: Assemble as shown in FIG. That is, the movable die 13 is fitted to the fixed die 12. ST02: Resin is injected into the cavity as shown in FIG. ST03: The first core is projected as shown in FIG. ST04: The second core is retracted as shown in FIG.

ST05: Since the volume reduction Q1 is smaller than the volume increase Q2, the second core consequently exerts a suction pump action, and the molten resin accumulated in the sprue 21 (see FIG. 3) enters the cavity 19 through the gate 22. Reach That is, the injection machine 1
This corresponds to the additional filling from the 1st side. With this, there is no fear of forming a cavity in the molded product. ST06: When the resin has hardened, the mold is opened to obtain a molded product. This molded product is equivalent to the card 102 shown in FIG.

FIG. 5 is a second control flow chart according to the method of the present invention, where STXX indicates a step number. ST11: Assemble as shown in FIG. That is, the movable die 13 is fitted to the fixed die 12. ST12: Resin is injected into the cavity as shown in FIG. ST13: The first core is projected as shown in FIG. ST14: The second core is retracted as shown in FIG.

ST15: Since the volume reduction Q1> the volume increase Q2, the second core consequently exerts an extrusion pump action,
Part of resin (excess) in cavity 19 (see FIG. 3)
Returns to sprue 21 through gate 22. That is, it corresponds to returning to the injection machine 11 side. ST06: When the resin has hardened, the mold is opened to obtain a molded product. This molded product is equivalent to the card 102 shown in FIG.

The first cylinder 17 and the second cylinder 18
Can be replaced with a pinion rack mechanism or a link mechanism. Therefore, the means for moving the first core 15 and the second core 16 back and forth may be appropriately determined.

[0025]

The present invention has the following effects due to the above configuration. According to a first aspect of the present invention, there is provided a first core that projects into the cavity after the cavity of the mold is filled with the resin, and a second core that is separated from the cavity after the resin is filled. The first core forms a thin portion, and the second core is formed. When manufacturing a thin resin plate having a thin portion locally by forming a thick portion, the volume increase of the cavity due to the retreat of the second core is set to be larger than the volume reduction of the cavity due to the protrusion of the first core. Then
The difference between the increased volume and the reduced volume is additionally filled from the injection machine side, and the resin is injected into the cavity with a uniform gap. A thin portion is formed by ejecting the first core after injection. Therefore, the flow of the resin becomes smooth, there is no fear that defects will occur, and it is possible to easily manufacture a good-quality thin resin plate of different thickness. At this time, the area of the first core and the ejection stroke, and the area of the second core and the retraction stroke can be independently determined by intentionally making a difference between the reduced volume of the cavity and the increased volume of the cavity. The shape of the thin resin plate can be arbitrarily determined.

According to a second aspect of the present invention, there is provided a first core that projects into the cavity after the cavity of the mold is filled with the resin, and a second core that is separated from the cavity after the resin is filled. When manufacturing a thin resin plate having a locally thin part by forming a thick part with two cores, the volume increase of the cavity due to the retreat of the second core rather than the volume decrease of the cavity due to the protrusion of the first core Is set to be small, and the difference obtained by subtracting the increase volume from the reduction volume is returned to the injection machine side, and the resin is injected into the cavity with a uniform gap. A thin portion is formed by ejecting the first core after injection. Therefore, the flow of resin becomes smooth,
There is no concern that defects will occur, and it is possible to easily manufacture a good-quality thin resin plate of different thickness. At this time, by intentionally making a difference between the reduced volume of the cavity and the increased volume of the cavity, the area of the first core and the ejection stroke,
The area and the backward stroke of the second core can be independently determined, and the shape of the thin resin plate can be arbitrarily determined.

According to a third aspect of the present invention, the tip of the second core is aligned with the tip of the first core in preparation for the first resin filling, and the tip of the second core is aligned with the tip of the first core. The walls of the cavities can be made flat and the flow of resin can be made smooth, and a high-quality thin resin plate without defects can be manufactured.

[Brief description of drawings]

FIG. 1 Principle diagram of an injection molding apparatus for carrying out the inventive method

FIG. 2 is a first operation explanatory diagram of FIG.

FIG. 3 is a second operation explanatory diagram of FIG.

FIG. 4 is a first control flow chart according to the method of the present invention.

FIG. 5 is a second control flow chart according to the method of the present invention.

FIG. 6 is a front view and a cross-sectional view of a conventional constant-thickness card.

FIG. 7 is a front view and a sectional view of a conventional different-thickness type card.

[Explanation of reference numerals] 10 ... Injection molding device, 11 ... Injection machine, 12 ... Mold (fixed mold), 13 ... Mold (movable mold), 15 ... First core, 16 ...
Second core, 19 ... Cavity.

Claims (3)

(57) [Claims] 1. A mold having a first core protruding into a cavity after being filled with resin and a second core separated from the cavity after the resin is filled, the first core forming a thin portion, and the second core When manufacturing a thin resin plate having a thin portion locally by forming a thick portion, the volume increase of the cavity due to the retreat of the second core is set to be larger than the volume reduction of the cavity due to the protrusion of the first core. Then, the difference between the increased volume and the reduced volume is additionally filled from the injection machine side, which is a method for manufacturing a thin resin plate. 2. A mold has a first core that projects into the cavity after being filled with the resin and a second core that is separated from the cavity after the resin is filled. The first core forms a thin portion, and the second core forms the thin portion. When manufacturing a thin resin plate that locally has a thin portion by forming a thick portion, the volume increase of the cavity due to the retreat of the second core is set to be smaller than the volume reduction of the cavity due to the protrusion of the first core. Then, the difference between the reduced volume and the increased volume is returned to the injection machine side, which is a method for manufacturing a thin resin plate. 3. The method for producing a thin resin plate according to claim 1, wherein the tip of the second core is aligned with the tip of the first core in preparation for the first resin filling.