JP2852344B2 - Mold for powder molding and powder molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for powder molding and a powder molding method.

[0002]

2. Description of the Related Art Conventional powder molding is widely used for molding the skin of automobile interior parts. There are mainly two types of molding methods used for this powder molding. One molding method, as shown in FIG. 13, is to remove a lid (not shown) into a hermetically sealed mold 45, put a thermoplastic resin powder through an opening, and rotate the mold 45 while rotating the mold 45. The outside is heated by the heater 47. The thermoplastic resin powder melts and adheres to the inner wall of the molding die 45 to form a resin molten layer. The molding die 45 is cooled to cure the molten resin layer, thereby forming a molded product. The molding is removed from the opening by removing the lid (not shown) of the molding die 45.

As shown in FIG. 12, another molding method is to blow hot air of about 450 ° C. through a powder inlet 43 into a molding die 41.
The inside of the mold 41 is heated to about 240 ° C. Thermoplastic resin powder is filled into the heated molding die 41 through a powder input port 43. This thermoplastic resin powder is a powder of a vinyl chloride resin, polyethylene, polypropylene or the like. The thermoplastic resin powder melts to form a molding die 41
Adheres to the inside to form a molten resin layer. Excess thermoplastic resin powder is discharged from the powder inlet 43 of the molding die 41. The molding die 41 is cooled to cure the molten resin layer, thereby forming a molded product. Then, the molded product is placed in a powder input port 4 of a molding die 41.
Remove from 3.

[0004]

The molded product formed by powder molding has no odor, has good coloring properties, and has a uniform wall thickness as compared with the molded product formed by paste sol molding. There is no sticky feeling. Therefore, it has been desired that a molded article to be directly held and used, such as a doll toy, is formed by powder molding.

However, in the case of the first powder molding method,
Since the filling of the thermoplastic resin powder can only be performed manually, it is difficult to completely automate the process, the work efficiency is poor, and mass production cannot be performed. . Further, the thermoplastic resin powder remaining inside cannot be discharged.

[0006] In the case of the second powder molding method, it can be completely automated. As a system for completely automating a series of operations of the powder molding, a specification filed by the applicant of the present invention (Japanese Utility Model Application No. 5-58) has been proposed. No. 58126). Powder molding is automatically performed by the heating furnace, the powdering section, the cooling section, and the demolding section of the powder slush molding apparatus.

However, as shown in FIG. 12, the molding die 41 used in this powder slush molding apparatus blows hot air from a powder injection port 43 to uniformly heat the entire interior of the molding die 41, The area of the opening 43 was larger than the maximum area of the molding die 41 in the width direction. Therefore, if the structure of the molding die becomes a complicated doll toy with a narrow powder inlet, a wide inside, and a plurality of branches like a hand-shaped molding die, hot air is blown from the powder inlet. However, the hot air at the same temperature cannot be distributed to the entire inside of the molding die, particularly to the details.

For example, even if hot air is blown from the powder inlet 5 of the dinosaur-type female mold 3 shown in FIG. 1, there is no way for the blown hot air to escape, and the powder is reflected by the inner wall of the female mold 3 and has a narrow powder inlet 5.
Since the hot air blows back from the air, the hot air blown is pushed back by the reverse flow, and the hot air cannot spread to details such as the arms.

Therefore, when the structure of a molding die used in a conventional powder slush molding apparatus becomes complicated, the molding die is not uniformly heated, has a uniform thickness, and has a smooth surface. Cannot be molded. In an extreme case, there is a problem that an unformed portion occurs. If the molded product cannot obtain a uniform thickness,
It breaks from thin parts and cannot be used for a long time. Therefore, a complicated molded product such as a doll toy was not formed.

The present invention has been devised in view of the above problems, and provides a molding die for powder molding capable of molding a molded article having a complicated structure such as a doll toy with a uniform thickness. The primary purpose is to provide. It is a second object of the present invention to provide a powder molding method in which a molding die for powder molding is heated from inside and outside to enhance the heating efficiency of the powder molding and uniformly heat the entire molding die.

[0011]

In the molding die for powder molding according to the first object, a powder inlet is formed on one side of a female mold, and the female mold is provided with a powder inlet for the female mold. A communication pipe is provided for communication, a holding member integrated with the communication pipe is formed on a periphery of an opening of the communication pipe, and an air outlet is formed in the holding member.

Further, the holding member may be formed of a flat plate, and the air outlet may be formed of a plurality of holes.

The powder molding method according to the second object has the following steps. (A) A powder injection port is formed on one side of the female mold, a holding member integrated with the female mold is formed around the periphery of the powder injection port, and a powder of a molding die in which an air outlet is formed in the holding member. A first step of blowing hot air toward the inlet, heating the inside of the female mold with hot air entering from the powder inlet, and heating the outside of the female mold with hot air entering from the blower of the holding member. (B) Fill the female mold with thermoplastic resin powder from the powder inlet,
A second step of adhering the thermoplastic resin powder to the inner surface of the female mold in a molten state or a semi-molten state, and then discharging excess thermoplastic resin powder from the inside of the female mold via a powder inlet. (C) A third step of cooling the female mold and taking out the molded product adhered to the inner surface from inside the female mold.

The following steps may be performed. (A) A powder injection port is formed on one side of the female mold, a holding member integrated with the female mold is formed around the periphery of the powder injection port, and a powder of a molding die in which an air outlet is formed in the holding member. A first step of blowing hot air toward the inlet, heating the inside of the female mold with hot air entering from the powder inlet, and heating the outside of the female mold with hot air entering from the blower of the holding member. (B) Fill the female mold with thermoplastic resin powder from the powder inlet,
A second step of adhering the thermoplastic resin powder to the inner surface of the female mold in a molten state or a semi-molten state, and then discharging excess thermoplastic resin powder from the inside of the female mold via a powder inlet. (C) A water leakage prevention plate is provided on the holding member to close the air outlet in a watertight manner, water is sprayed on the female mold to cool the female mold, and a molded product attached to the inner surface is taken out from the female mold. Process.

[0015]

The molding die for powder molding according to the present invention has the above-mentioned structure and is used as follows. In the molding die, the holding member is attached to the transfer frame of the powder slush molding device described above, and a heating furnace, a powdering section,
It is conveyed to the cooling section and the demolding section. In the heating furnace, hot air is blown toward the female powder input port side, and hot air entering from the powder input port heats the inside of the female die, and hot air input from the blowing port of the holding member heats the outside of the female die. . In the powdering section, the thermoplastic resin powder is filled into the female mold from the powder inlet, and the thermoplastic resin powder is adhered to the inner surface of the female mold in a molten state or a semi-molten state, and the excess thermoplastic resin powder is removed from the female mold. Discharge from inside through the powder inlet. In the cooling section, the female mold is cooled. In the demolding section, the molded product adhered to the inner surface is taken out of the female mold.

In the cooling section, when the female mold is cooled with water, if a water leakage preventing plate is provided on the holding member to close the air outlet in a watertight manner, water does not leak from the air outlet.

A female pipe is provided with a communication pipe which communicates with the female powder input port. If a holding member is formed around the opening of the communication pipe, the source of hot air is separated from the powder input port. The temperature of the hot air near the mouth is lowered, and scorching of the molded portion near the powder inlet can be prevented.

Further, when the holding member is formed of a flat plate, the female mold can be stably held, and when the blowing port is formed of a plurality of holes, the processing can be performed easily and inexpensively.

[0019]

An embodiment of the present invention will be described below with reference to the drawings. 1 shown in FIG. 1 is a molding die for powder molding. The molding die 1 includes a dinosaur-shaped female die 3, a communication tube 7, and an iron flat plate 11 (holding member). The communication pipe 7 is formed integrally with the female mold 3 so as to surround the powder input port 5 formed at the lower part (the back of the dinosaur) of the female mold 3. The flat plate 11 is integrally attached to the periphery of the opening 9 of the communication pipe 7. The molding die 1 is formed by integrally forming the female mold 3 and the communication pipe 7, and separately forming the flat plate 11 on the communication pipe 7.
Was formed by welding such as welding. But,
The female mold 3, the communication pipe 7, and the flat plate 11 may be separately formed, and each may be formed by welding or the like.

As shown in FIG. 2, the flat plate 11 has a plurality of holes 13 (blowers). The shape of the hole 13 does not need to be specified, and various shapes such as a round shape, a triangular shape, and a square shape can be considered. For example, as shown in FIG. 3, a rectangular hole 15 (blower) is formed in the flat plate 11 at a position where the head, the left body, the right body, and both legs of the female mold 3 face each other. I do not care. Further, the flat plate 11 may be formed in a substantially X shape as shown in FIG. In this case, a portion other than the portion forming X is a blow port. The powder inlet 5 has an area smaller than the maximum area in the width direction in the female mold 3.

The flat plate 11 of the forming die 1 is attached to a transfer frame 17 of a powder slush forming apparatus by bolts or the like, and transferred to a heating furnace, a powdering section, a water cooling section, and a demolding section. More specifically, FIG.
As shown in (1), when the female mold 3 is turned up and the powder inlet 5 is placed downward and attached to the transfer frame 17, the powder is transferred to the heating furnace by the transfer frame 17. In the heating furnace, the molding die 1
It is heated by hot air blown upward from the bottom. That is, the hot air passes through the opening 9 of the communication pipe 7, the communication pipe 7, and the powder inlet 5 to heat the inside of the female mold 3. At the same time, hot air heats the outside of the female mold 3 through the holes 13 of the flat plate 11.

In the flat plate 11 shown in FIG. 3, the outside of the female mold 3 is heated by hot air passing through the hole 15 and the flat plate 1 shown in FIG.
In 1, the outside of the female mold 3 is heated through portions other than the portion where the hot air forms X. As shown in FIG. 6, a plurality of pipes 19 may be provided on the flat plate 11, and hot air blown toward the flat plate 11 may be blown to a predetermined portion (particularly a portion to be heated) of the female mold 3 through the pipe 19. . In this case, the pipe 19 can be formed in a straight shape, a bent shape, or the like.

The molding die 1 heated by the heating furnace is conveyed by the conveying frame 17 to the powdering section. Flat plate 1
The powder box 21 is joined to the first box 1 (see FIG. 7).
The powder box 21 contains a thermoplastic resin powder 23.
Is filled. At the top of the powder box 21,
An opening 25 that joins the opening 9 of the communication pipe 7 is formed. In this state, the molding die 1 is rotated. rotation angle,
The number of rotations is freely set based on the structure of the female mold 3.

The thermoplastic resin powder 23 in the powder box 21 enters the female mold 3 through the opening 25 and the communication pipe 7 as shown in FIG. Since the inside of the female mold 3 is heated,
The resin powder adheres to the female mold 3 in a molten state or a non-molten state, and forms a resin melted layer 27 of 0.5 to 3 mm. FIG.
As shown in (2), when the female mold 3 is turned upward and the powder inlet 5 is turned downward and the rotation is stopped, the thermoplastic resin powder 23 that has not adhered in the female mold 3 is collected in the powder box 21.

The powder box 21 is separated from the molding die 1, and the molding die 1 is transported by the transport frame 17 to the water cooling section. The transfer frame 17 is fixed to the rotary frame 29 by a clamp or the like, and the rotary frame 29 rotates the molding die 1 by about 180 degrees, and the female die 3 is positioned below. A heat-resistant silicone gasket 31 is provided on the lower surface of the rotating frame 29 as a plate for preventing water leakage.
Are provided.
Are closed in a watertight manner.

The water sucked up by the pump 35 from the water tank 33 is jetted out by the jet pipe 37 and sprayed on the female mold 3 to cool it. The resin melt layer 2 adhered to the inner surface of the female mold 3
7 is cured to form a molded product. Since the plurality of holes 13 of the flat plate 11 are closed in a watertight manner by the packing 31,
Water does not leak from the water cooling section. The rotating frame 29 is separated from the transport frame 17, and the molding die 1 is transported by the transport frame 17 to the demolding section. In the removal part, the molded product in the female mold 3 is taken out from the opening 9 of the communication pipe 7.

In the above embodiment, the molding die 1 was constructed by separating the female mold 3 and the flat plate 11 by the communication pipe 7. When the molding die 1 is heated with hot air, it is necessary to heat the entire female mold 3 to the melting temperature of the thermoplastic resin powder. Therefore, the portion farthest from the hot air jet source is heated to the minimum required temperature. It is necessary to blow hot air at a considerably high temperature to the powder inlet 5. As a result, the powder inlet 5 of the female mold 3 close to the hot air jetting source is heated more than necessary, and the thermoplastic resin powder near the powder inlet 5 is scorched and may cause molding failure. Therefore, the communication pipe 7 is provided to separate the powder input port 5 of the female mold 3 from the flat plate 11. However, when the farthest part of the female mold and the powder input port are close, or as shown in FIG. When cutting can be performed later even if molding failure occurs near the powder input port due to high temperature, a flat tube 11 is directly connected to the powder input port 5a of the female mold 3a without using a communication pipe.
May be attached.

[0028]

According to the present invention, a molding die for powder molding is
Since the hot air entering from the powder inlet heats the inside of the female mold and the hot air entering from the air blowing port of the holding member heats the outside of the female mold, there is an effect that the entire female mold is uniformly heated. Therefore,
Even a molded article having a complicated structure, such as a doll toy, which could not be molded conventionally, can be molded with a uniform thickness. In addition, the female mold is provided with a communication pipe communicating with the female powder input port,
When the holding member is formed on the periphery of the opening of the communication pipe, the source of the hot air is separated from the powder inlet, so that the temperature of the hot air near the powder inlet decreases, thereby preventing the molded portion near the powder inlet from scorching. There is an effect that can be. Further, when the holding member is formed of a flat plate, the female mold can be stably held, and when the blowing port is formed of a plurality of holes, there is an effect that processing can be performed easily and inexpensively.

In the powder molding method according to the present invention, since the female mold is simultaneously heated from the inside and the outside, the heating efficiency is good and the whole female mold can be uniformly heated.
In addition, when the female mold is cooled with water, the air outlet is closed in advance with a water leakage prevention plate, so that there is an effect that water does not leak from the air outlet.

[Brief description of the drawings]

FIG. 1 is a partially sectional side view showing one embodiment of a molding die according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a plan view of another embodiment.

FIG. 4 is a plan view of another embodiment.

FIG. 5 is an explanatory view showing one embodiment of a molding method according to the present invention.

FIG. 6 is a partially sectional side view showing another embodiment.

FIG. 7 is an explanatory view showing one embodiment of a molding method according to the present invention.

FIG. 8 is an explanatory view showing one embodiment of a molding method according to the present invention.

FIG. 9 is an explanatory view showing one embodiment of a molding method according to the present invention.

FIG. 10 is an explanatory view showing one embodiment of a molding method according to the present invention.

FIG. 11 is a partially sectional side view showing another embodiment.

FIG. 12 is a sectional view showing a conventional technique.

FIG. 13 is a sectional view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molding die 3 Female mold 5 Powder inlet 7 Communication tube 9 Opening port 11 Flat plate (holding member) 13 Holes (Blower port) 15 Holes (Blower port) 17 Transport frame 19 Pipe 21 Powder box 23 Thermoplastic resin powder 25 Opening 27 Resin fusion layer 29 Rotating frame 31 Packing 33 Water tank 35 Pump 37 Jet pipe

Claims (4)

(57) [Claims] 1. A powder inlet is formed on one side of a female mold, and a communication pipe is provided in the female mold to communicate with the powder inlet of the female mold.
A molding die for powder molding, wherein a holding member integrated with the communication pipe is formed at a periphery of an opening of the communication pipe, and an air blowing port is formed in the holding member. 2. The molding die for powder molding according to claim 1, wherein the holding member is a flat plate, and the blowing port is a plurality of holes. 3. A powder molding method comprising the following steps. (A) A powder injection port is formed on one side of the female mold, a holding member integrated with the female mold is formed around the periphery of the powder injection port, and a powder of a molding die in which an air outlet is formed in the holding member. A first step of blowing hot air toward the inlet, heating the inside of the female mold with hot air entering from the powder inlet, and heating the outside of the female mold with hot air entering from the blower of the holding member. (B) Fill the female mold with thermoplastic resin powder from the powder inlet,
A second step of adhering the thermoplastic resin powder to the inner surface of the female mold in a molten state or a semi-molten state, and then discharging excess thermoplastic resin powder from the inside of the female mold via a powder inlet. (C) A third step of cooling the female mold and taking out the molded product adhered to the inner surface from inside the female mold. 4. A powder molding method comprising the following steps. (A) A powder injection port is formed on one side of the female mold, a holding member integrated with the female mold is formed around the periphery of the powder injection port, and a powder of a molding die in which an air outlet is formed in the holding member. A first step of blowing hot air toward the inlet, heating the inside of the female mold with hot air entering from the powder inlet, and heating the outside of the female mold with hot air entering from the blower of the holding member. (B) Fill the female mold with thermoplastic resin powder from the powder inlet,
A second step of adhering the thermoplastic resin powder to the inner surface of the female mold in a molten state or a semi-molten state, and then discharging excess thermoplastic resin powder from the inside of the female mold via a powder inlet. (C) A water leakage prevention plate is provided on the holding member to close the air outlet in a watertight manner, water is sprayed on the female mold to cool the female mold, and a molded product attached to the inner surface is taken out from the female mold. Process.