JPH0142807B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding a synthetic resin molded product that requires strength in some parts.

For example, in the case of a synthetic resin molded product such as a travel bag, strength is required around the opening.

Therefore, when molding this by injection molding, conventionally, a shape is adopted in which the thickness of that part is increased in order to obtain strength in that part, that is, around the opening.

However, since sufficient strength cannot be obtained at this level, it is necessary to further reinforce with aluminum sash or the like.

On the other hand, if a material with a high flexural modulus is used, such as glass or carbon fiber-containing resin, the strength problem can be solved, but there is the problem that injection molding must be performed at a higher pressure, and the material cost increases. Since it becomes expensive, the price of the product increases, which is undesirable.

The object of the present invention is to solve the above-mentioned problems, provide sufficient strength without reinforcing it with aluminum sash, etc., and to mold it at low cost.

Therefore, the structure of the present invention for achieving the above object uses a matted metal die for compression molding,
Using an extruder, extrude the thermoplastic resin containing the required amount of reinforcing material to a predetermined part of the lower mold corresponding to the part of the molded product that should be reinforced, and extrude it to a predetermined part of the lower mold other than the above-mentioned parts. After placing the thermoplastic resin containing no reinforcing material or having a small amount of reinforcing material, the mold is immediately clamped and cooled under pressure.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

This embodiment relates to the molding of a box-shaped shell B constituting the main body or lid of a travel bag. The fitting portion 4 requires strength.

Therefore, to form the shell B, a pressure press E is used.
Matted metal die A for compression molding attached to
That is, a mold having shear edges 6 and 7 where male and female molds 1 and 5 engage along the periphery of the molded product, and this mold A.
Two thermoplastic resin extruders C and D are used, each supplying different types of resin materials.

For the mold A, a male mold 1 is mounted on a fixed surface plate 8 provided on the lower side of the pressure press E, and a female mold 5 is mounted on a movable surface plate 10 provided on the upper side and moved up and down by a cylinder 9.

Furthermore, the mold A includes a main molding part 11 that molds most of the shell B except for the fitting part 4, and a main molding part 11 that molds most of the shell B except for the fitting part 4.
It has a fitting part molding part 12 that is continuously provided in a plane annular shape on one periphery, and the fitting part molding part 12 is formed on the male mold 1.
It consists of a concave groove 13 provided in the mold and a protrusion 14 of the female die 5 that is inserted into the concave groove 13 when the mold is clamped.

On the other hand, the two thermoplastic resin extruders C and D are
One of them, C, is for filling the fitting part molding part 12 of the mold A with resin (hereinafter referred to as a fitting part filling extruder), and the other D is a part for filling the main molding part 11 with resin. (hereinafter referred to as the main body filling extruder), the former C is provided with a nozzle 15 formed to extrude the resin in a string shape, and the latter D is provided with a nozzle 15 formed in a structure to extrude the resin in the form of a sheet. A formed die 16 is provided.

The two extruders C and D are arranged on the sides of the pressure press E, at right angles or in opposite directions, and are fixed on movable beds 17 and 18, respectively, which move under computer control.

The movable bed 17 of the extruder C for filling the fitting part moves in the horizontal plane X and Y axis directions, and the extruder D for filling the main body part moves.
The movable bed 18 is configured to move in the front and back direction on a horizontal plane.

The extruder C for filling the fitting part operates the movable bed 17 to align the nozzle 15 with the groove 13 of the male mold 1 when the mold A is open, and then operates the extruder C. A necessary amount of glass fiber or carbon fiber is put into a thermoplastic resin such as polypropylene through the nozzle 15, extruded in a molten state into a string shape, and the nozzle 15 is moved around the groove 13 while dropping it into the groove 13. let

This extruder C for filling the fitting part has nozzle 1.
After the resin string 5 has gone around the concave groove 13 once, extrusion of the resin is stopped, the resin string 2 is cut, and the resin string 2 is retreated to the outside of the press E.

On the other hand, the extruder D for filling the main body has either finished filling the groove 13 with resin by the extruder C for filling the fitting part, or has reached a position where it does not interfere with the movement of the extruder C for filling the fitting part. After that, the movable bed 18 is moved forward to extrude and place the molten resin 3 containing no glass fiber or carbon fiber in a sheet form from the die 16 onto the main molding part 11 of the male mold 1, and immediately retreats after extrusion is completed. and evacuate outside Press E. Although glass fibers and carbon fibers do not need to be mixed in this sheet-shaped molten resin as described above, a small amount of glass or carbon fibers may be mixed in as necessary.

The amount of each resin is controlled to an appropriate amount to fill the cavity of the mold A by adjusting the discharge amount of the nozzle 15 and the die 16 and the moving speed of the extruders C and D.

The above-mentioned series of operations of the two extruders C and D and control of the amount of resin are all controlled by a computer.

After the extruder D for filling the main body is evacuated to the outside of the press E, the press E is operated to lower the female mold 5 and clamp the mold.

This pressurizes the resin and causes it to flow inside mold A.
The resin that fills the cavity and is supplied by the extruder D for forming the main body and is not mixed with glass or carbon fiber, or is mixed in a small amount, and the resin that is supplied by the extruder C for forming the fitting part. The resin containing glass or carbon fiber is completely integrated. The temperature of mold A is adjusted to an appropriate temperature below the resin curing temperature.

Therefore, the resin is cooled and hardened, and the molding is completed.
Thereafter, the mold A is opened and demolded to obtain a box-shaped bag shell B in which the fitting part 4 formed in the opening is reinforced with glass or carbon fiber.

In the above example, extruders C and D were moved to supply resin to the male mold, but it is also possible to connect the extruder main body and the nozzle or die with a pipe with an indirect connection so that only the nozzle or die is connected. It is also possible to move it.

In addition, the sheet-shaped molten resin 3 extruded by the extruder D for filling the main body does not need to be directly extruded onto the male die 1.
It is also optional to extrude it outside the male mold 1, cut it, and move it onto the male mold 1 using a suitable holding and moving means such as a magic hand.

Furthermore, it is also optional whether the string-shaped molten resin 2 extruded by the extruder C for filling the fitting portion or the sheet-shaped molten resin 3 extruded by the extruder D for filling the main body be charged first.

Since the present invention has the above configuration, it has the following advantages.

(1) Supply molten resin containing enough glass or carbon fiber to only the parts that require strength, and add glass or carbon fiber to other parts depending on the required strength. It is economical to use low-cost thermoplastic resins, or to use only the required amount of resin with any fiber content.

(2) By extruding a resin containing glass or carbon fibers using an extruder, the fibers are oriented in the longitudinal direction, so sufficient strength can be achieved.

[Brief explanation of drawings]

The drawings show an embodiment of the method of molding a synthetic resin molded article of the present invention that partially requires strength, and FIG. FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a cross-sectional plan view showing a state in which resin is supplied for parts that do not require much strength.
4 to 6 are enlarged cross-sectional views of important parts showing the flow state of the resin due to mold clamping, and FIG. 7 is a cross-sectional view showing a part of the molded product. A...Matte metal die (mold), B...Molded product (bag shell), C...Extruder (extruder for filling the fitting part), D...Extruder (extruder for filling the main body) ,
1... Male mold, 2... Molten thermoplastic resin containing reinforcing material, 3... Molten thermoplastic resin containing no reinforcing material or having a low reinforcing material content.

Claims (1)

[Claims] 1 Using a matted metal die for compression molding, extrude the thermoplastic resin containing the necessary amount of reinforcing material into a predetermined part of the lower die corresponding to the part of the molded product to be reinforced, and place it using an extruder. After placing the thermoplastic resin extruded by an extruder and containing no reinforcing material or containing a small amount of reinforcing material in the specified location of the lower mold, the mold should be immediately clamped and cooled under pressure. Characteristics: A method for molding synthetic resin molded products that partially require strength.