JPH0755518B2 - Injection simultaneous painting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to an injection simultaneous painting method for forming a pattern at the same time when a resin product is injection-molded, and in particular, a preparatory sheet for painting. The present invention relates to improvement of a heating system in molding.

(Prior Art) Conventionally, as a method of simultaneously forming a pattern at the time of injection molding a resin product, a belt-shaped painted sheet having an arbitrary pattern in a predetermined array is conveyed and a part thereof is used as a molding female mold. Hold facing each other, then the portion of the painted sheet held facing the female mold is heated between the lid member and the female mold and vacuum pressure air molded to adhere to the molding surface of the female mold, Then withdraw the lid member and align the male mold for molding with the female mold,
It is known that a molten resin is injected into a cavity between both molds.

(Problems to be Solved by the Invention) By the way, in the conventional simultaneous injection molding method, as heating in the pre-molding of the painting sheet, a radiant heating method by a heater or a lid member incorporating a heater is brought into contact with the painting sheet. The method of making is adopted.

However, in this type of heating method, it takes time to heat the decorative sheet, and when sufficient heating softening cannot be obtained,
There is a problem that unevenness occurs in the elongation of the decorative sheet and the decorative sheet is cut or distorted.

The present invention has been made in view of the present situation, and an object of the present invention is to provide an injection simultaneous painting / molding method capable of shortening the heating time of the painting sheet and eliminating heating spots.

[Structure of Invention]

(Means for Solving the Problems) In the present invention, heating of the painted sheet is performed by high-frequency dielectric heating using the female die and the lid member as electrodes, and vacuum pressure air molding is performed to adhere the sheet to the female molding surface. It is characterized by doing so.

(Operation) In the injection simultaneous painting method according to the present invention, the heating of the painting sheet is performed by high-frequency dielectric heating using the female die and the lid member as electrodes. Therefore, the heating time of the painting sheet is shortened. In addition, the internal heat generation allows uniform heating.

(Example) Hereinafter, one aspect of the present invention will be described with reference to the drawings.

In FIG. 1 to FIG. 3, reference numeral 1 denotes a female mold which constitutes an injection molding die together with a male mold 2. The female mold 1 is
It is fixed to the moving plate 3 of the injection molding device, and also the male mold 2
Are fixed to the fixing member 4, and the female die 1 is configured to move in the perspective direction with respect to the male die 2. And both types
The injection molding die is clamped by the combination of 1 and 2, and the molten resin is injected into the cavity 5 through the injection nozzle 6 provided in the male die 2.

Between the molds 1 and 2 configured in this way, there is arranged a belt-shaped picture sheet 7 which is conveyed in a direction orthogonal to the facing direction of the molds 1 and 2. The picture sheet 7 will be described later. It is guided by the feeding device 8 and is intermittently conveyed one pitch at a time.

That is, the feeding device 8 includes a frame 9 attached to the moving plate 3, and the unwinding roll 10 around which the decorative sheet 7 is wound is provided on the frame 9. Then, the picture-attached sheet 7 delivered from the unwinding roll 10 is drawn out between the molds 1 and 2 through the tension roller 11 and the guide roller 12 in order, and further illustrated via the guide roller 13 and the tension roller 14. Not to be wound up on a winding roll.

This painting sheet 7 is used for gravure printing, offset printing, screen printing, etc. on one side of a 0.1 to 1 mm thick dielectric sheet made of polyvinyl chloride, vinylidene chloride, polyethylene, polypropylene, polyamide, polyurethane, acetal, polycarbonate, polyester, etc. It is formed by arranging a large number of patterns continuously or intermittently by printing means,
A mark detected by a widthwise positioning sensor 15 fixed at the exit side position of the guide roller 12 and a running direction positioning sensor fixed at the entrance side position of the guide roller 13 are provided on the picture-added sheet 7. Marks (not shown) detected by 16 are provided respectively, and an adhesive layer is provided on the back surface of the picture-added sheet 7 if necessary. If the design is for reverse printing or transfer, the printed sheet 7 is set so that the printing surface faces the male mold 2, and if the design is front printing, the printing surface faces the female mold 1. Is set to.

As shown in FIG. 3, a lid member 17 for preforming the decorative sheet 7 together with the female mold 1 is arranged at a portion of the decorative sheet 7 thus set on the male die 2 side.

The lid member 17 is formed of a material such as metal, wood, silicon, or gypsum in a male mold similar to a plug assisted plug. Inside the lid member 17 and the female mold 1, Electrodes 18 for high frequency dielectric heating are provided respectively. Further, at the tip of the lid member 17 and the inside of the female mold 1, at the time of vacuum pressure forming of the painted sheet 7 shown in FIG.
A compressed air hole 19 for sending compressed air into the cavity 5 and a vacuum hole 20 for vacuuming the inside of the cavity 5 are provided respectively.

On the back side of the lid member 17, a rod tip 21a of a fluid pressure cylinder 21 whose base end is pivotally attached to a device frame (not shown) is pivotally attached, and the lid member 17 is expanded and contracted by the fluid pressure cylinder 21. It is adapted to move in the conveying direction of the picture-added sheet 7. When the lid member 17 is moved to the position of the female mold 1 as shown in FIG. 2, the lid member 17 is pressed toward the female mold 1 by a fluid pressure cylinder (not shown), and its tip is fixed as shown in FIG. It is adapted to be pushed into the female mold 1.

Next, the injection simultaneous molding method will be described.

In the state shown in FIG. 1, first, the feeding device 8 is activated to convey the picture-added sheet 7 downward in the drawing. Then, when both positioning sensors 15 and 16 detect a mark (not shown) on the painting sheet 7, the feeding of the painting sheet 7 is stopped.
As a result, the predetermined pattern is accurately aligned with the female mold 1.

In parallel with the conveyance of the picture-added sheet 7, the fluid pressure cylinder 21
Is extended, the lid member 17 moves to the position of the female die 1 and stops as shown in FIG.

Then, a high-frequency electric field is applied between the electrodes 18 of the female die 1 and the lid member 17, and high-frequency dielectric heating is applied to the painted sheet 7
The portion located between the two electrodes 18, 18 is softened by heating. Immediately thereafter, the lid member 17 is pushed into the female die 1 by a fluid pressure cylinder (not shown) as shown in FIG. 3, and the air is exhausted from the vacuum hole 20 and the compressed air is supplied from the compressed air hole 19, so that the painting Vacuum pressure forming of the sheet 7 is performed. As a result, the decorative sheet 7 is attached to the molding surface of the female mold 1.

For the high frequency dielectric heating, for example, a high frequency generator with an output of 60 Kw and an oscillation frequency of 27.12 MHz is used, and both electrodes 18,1
It is carried out by applying a high frequency electric field for 8 seconds between 8.

When the preforming of the painted sheet 7 is completed in this way, the lid member 17 is pulled out of the female die 1 by the operation of a fluid pressure cylinder (not shown), and the lid member 17 is removed by the reduction operation of the fluid pressure cylinder 21. Retract to a position that does not interfere with injection molding.

Next, the female die 1 moves to the male die 2 side, the two dies 1 and 2 are united to clamp the injection molding die, and the injection nozzle 6 is placed in the cavity 5 in the die. The molten resin is injected through. As a result, a molded article with a synchronized pattern can be obtained.

It should be noted that this decorative molded product is separated from the decorative sheet 7 if necessary, and is discharged to the outside of the female mold 1 by the discharging mechanism.

As described above, since the heating of the decorative sheet 7 at the time of preforming is performed by the high frequency dielectric heating using both electrodes 18, 18, the heating time can be shortened as compared with the heating by the heater. . Also, because of internal heat generation,
Can be heated uniformly without heating spots.

Also, by using the high frequency dielectric heating method, the lid member
A material other than metal can be used for 17, and the lid member 17 can be manufactured at low cost by using a wooden mold, a silicon mold, or a gypsum mold.

Further, since the lid member 17 is a male type similar to the plug of the plug assist molding, the painting sheet 7 can be uniformly and easily stretched, and can be easily stretched as compared with the case where the flat plate-shaped lid member 17 is used for vacuum pressure molding. Deep drawing is possible.

〔The invention's effect〕

As described above, according to the present invention, the heating of the decorative sheet during preforming is performed by high-frequency dielectric heating using the female die and the lid member as electrodes. Therefore, the heating time of the decorative sheet can be shortened. In addition, because of the internal heat generation, the painted sheet can be uniformly heated without spots. For this reason,
It is possible to uniformly form a painted sheet.

[Brief description of drawings]

1 to 3 are explanatory views sequentially showing the injection simultaneous molding method according to the present invention in the order of steps. DESCRIPTION OF SYMBOLS 1 ... Female type, 2 ... Male type, 5 ... Cavity, 6 ... Injection nozzle, 7 ... Painting sheet, 8 ... Feeding device, 15, 16 ... Positioning sensor, 17 ... Lid member, 18 ... Electrode, 19 ... Pressure hole, 20 ... vacuum hole.

Claims (2)

[Claims] 1. A belt-shaped decorative sheet having an arbitrary pattern in a predetermined arrangement is conveyed and a part thereof is held at a position facing a female mold for molding, and then facing the female mold of this decorative sheet. The held part is heated between the lid member and the female mold, and vacuum pressure forming is applied to the molding surface of the female mold, then the lid member is retracted and the male mold for molding is fitted to the female mold. In the injection simultaneous molding method of injecting a molten resin into the cavity between the two molds, the above-mentioned painting sheet is heated by high frequency dielectric heating using a female mold and a lid member as electrodes, Method. 2. The injection simultaneous painting method according to claim 1, wherein the lid member has a male shape similar to that of a plug used for plug assist molding.