JPH05320706A - Production of hollow article, produced part for hollow article and hollow article produced with hollow article production - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a hollow product molding method for conveniently molding a hollow product from a hard and sinterable material such as metal or ceramic by using a sandwich molding technique. [Structure] A core layer forming material (JC) made by kneading sinterable fine particles and a resin binder that can be removed by heating and is removable, and a core layer forming material (JC) made of a resin binder are compositely injected to form the core Sandwich molding (M1) in which the layer forming material (JC) is covered with the skin layer forming material (JS)
And then heat-treating the sandwich molded product (M1) to remove the resin binder of the molded product, and to sinter the sinterable fine particles in the skin layer forming material (JS) to produce a hollow product. To mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite injection molding technique for injecting two or more kinds of different materials, and more specifically, a sandwich molding technique for producing a sandwich molding product in which a core layer forming material is coated with a skin layer forming material. Regarding the use of.

[0002]

2. Description of the Related Art Conventionally, in the field of compound injection molding, two kinds of molten resin have been injected into a mold by a compound injection molding machine (A) as shown in FIG. A sandwich molding technique for obtaining a sandwich molded article composed of a skin layer (JS) surrounding the is known, and is used, for example, in multilayer parison molding for blow molding of plastic bottles.

On the other hand, in order to manufacture a hollow product made of a hard material such as metal or ceramic, the hollow product is appropriately divided into partial shapes, and then these partial molded products are welded and fired. Hollow products are obtained by the so-called shell molding technique of joining by joining. Further, only a metal such as aluminum, which is barely ductile and malleable, can be molded into a final hollow product at a time by drawing or the like, without dividing and molding.

By the way, recently, a molding technique for obtaining a hollow product from a resin in which a hard material such as metal or ceramic is mixed is known, for example, from Japanese Patent Laid-Open No. 4-70313. The molding technique described in the publication is a split mold that can divide the fixed mold among the movable mold and the fixed mold that form the primary molding cavity, and gasification is possible in the primary molding cavity. A secondary molding cavity is formed by injecting a different thermoplastic primary injection resin to mold the core, and leaving this core in the movable mold while abutting the fixed mold for secondary molding here. Then, the secondary molding resin containing metal, ceramics, etc. is injected into this cavity to mold the secondary molding product, and the secondary molding product is fired to form the core molding resin. It is an injection / firing technology that gasifies to produce hollow products.

However, in the above injection / firing molding technique, since the core is secondary-molded while leaving the core in the movable mold, the secondary-molded product and the final product obtained by firing the core are said to be hollow. The hollow part is open to the outside,
It is not possible to obtain a completely hollow product. The final hollow product is a resin molded product in which a hard material such as metal or ceramics is mixed, and cannot be obtained as a product made of a fired product of the above hard material.

[0006]

DISCLOSURE OF THE INVENTION The present invention utilizes a sandwich molding technique to easily mold a complete hollow product whose hollow portion is not exposed to the outside even from a hard material such as metal or ceramic. It is to provide a molding method.

[0007]

Thus, according to the invention of "Claim 1" of the present application, "a skin layer forming material (JS) in which sinterable fine particles and a resin binder which can be removed by heating are kneaded, and Core layer forming material (J
C) and composite injection of the core layer forming material (JC) to form a sandwich molded article (M1) coated with a skin layer forming material (JS), and then heat-treating the sandwich molded article (M1). By doing so, a method for producing a hollow article is provided, which comprises removing the resin binder of the molded product and sintering the sinterable fine particles in the skin layer forming material.

In the molding method of the present invention, a kneaded product of sinterable fine particles and a resin binder is used as the skin layer forming material (JS). The sinterable particles include metal fine particles,
Ceramic fine particles are preferably used. Any size of these fine particles may be used as long as it does not hinder the injection by smoothly flowing through the sprue or runner of the composite molding machine.

When the resin binder is kneaded with the sinterable fine particles, it retains fluidity so as not to impair the function of injection molding, and a heating atmosphere until the sinterable particles are sintered. Those that can be completely vaporized and removed below are used. As such a resin binder, those known in the art can be used as they are.

The above-mentioned skin layer forming material (JS) comprises sinterable fine particles in an amount sufficient to secure the intended shape of the hollow article,
This amount of the sinterable fine particles is uniformly dispersed, and the amount of the resin binder is sufficient to impart fluidity to the extent that the function of the composite injection molding machine (A) is not impaired.

In the present invention, the resin binder used in the skin layer forming material (JS) is used as the core layer forming material (JC).

For sandwich molding in the manufacturing method of the present invention, a normal composite injection molding machine for sandwich molding is preferably used. In the composite injection molding machine, after injecting the skin layer forming material, then injecting the core layer forming material, and finally injecting a small amount of the skin layer forming material, the molding conditions of the resin binder used for these materials are set. Then, a sandwich molded product (M1) is obtained.

Sandwich molded product (M1) obtained above
Is a molded product for hollow articles according to the present invention "claim 2".

The sandwich molded article (M1) is subjected to heat treatment under the conditions that at least the sinterable particles contained therein can be sintered. The binder is removed (hereinafter referred to as degreasing). A vacuum sintering furnace, for example, is preferably used for degreasing the resin binder. An example of heating conditions when using such a vacuum sintering furnace is 500 ° C. and about 50 hours.

By the above-mentioned degreasing treatment by heating, the resin binder is removed and the sinterable particles are bonded to each other. However, the sinterable particles only have a slight volume shrinkage and are not completely sintered. Not so far, it is so-called porous. Therefore, when the porous body is heated under the condition that it is completely sintered, the entire body shrinks to obtain a hollow sintered body. Further sintering conditions for sinterable particles

The hollow article obtained by the production method of the present invention means any hollow member regardless of parts or products.

[0017]

According to the present invention, a material for forming a skin layer in which sinterable fine particles and a resin binder which can be removed by heating are kneaded
(JS) and a core layer forming material (JC) consisting of the above resin binder
And composite injection, and the core layer forming material (JC) is coated with a skin layer forming material (JS) to obtain a sandwich molded article (M1), by heat-treating this sandwich molded article (M1),
The resin binder component of the molded product is vaporized with heating, and the sinterable fine particles are sintered and fused close to each other by heating, and the shape of the molded product remains. Then, the hollow product (G1) is formed by subjecting this to heat treatment under the condition that the sinterable particles are completely sintered.

[0018]

The present invention will be described in detail below with reference to the illustrated embodiments, but the present invention is not limited thereto. Example 1 FIG. 1 is a plan view of a composite injection molding machine (A) used in the molding method of the present invention. According to the figure, the resin injection device (B) in the center
Is installed, and on both sides of it, a heating cylinder (c1) (d1), rotary screws (c2) (d2), resin hoppers (c3) (d3) and screw drive parts (c4) (d4) 1 resin kneading supply section (C) and 2nd resin kneading supply section (D) are provided, the resin kneading supply section (C) is a connecting tube (c5), and the resin kneading supply section (D) is a connecting tube (d
Each of them is connected to the resin injection device (B) at 5).

In the first and second resin kneading supply sections (C) (D), when the screws (c2) (d2) in the heating cylinders (c1) (d1) are operated, the molten resin gradually kneaded at the tips. Are accumulated, the screw (c2) (d2) is retracted accordingly, and when the screw (c2) (d2) is advanced when a predetermined amount of kneaded molten resin has accumulated, the kneaded molten resin accumulated at the tip part Will be extruded, and will be injected into the mold (4) from a predetermined resin passage described later in the resin injection device (B) through the connecting cylinders (c5) and (d5).

The resin injection device (B) and the first and second resin kneading supply parts (C) and (D) are entirely moved forward and backward by the drive of the main drive cylinder (E), and the resin injection device (B) Outer cylinder body (1)
The tip of is contacted with and separated from the sprue bush (41) of the mold (4).

FIG. 2 shows a schematic cross section of the resin injection device (B). The main structure is that the outer cylinder (1), the inner cylinder (2), the needle (3), and the inner cylinder (2). For detecting the positions of the inner cylinder drive cylinder (b1) that moves forward and backward, the needle drive cylinder (b2) that moves with the inner cylinder (2) to move the needle (3) forward and backward, and the needle (3). Position detecting device (5a), position detecting device (5b) for detecting the position of the inner cylinder (2), CPU (5),
An inner cylinder proportional valve (51) for controlling the inner cylinder drive cylinder (b1),
It is composed of a needle proportional valve (52) for controlling the needle drive cylinder (b2). The proportional valve (51) (52)
Needless to say, can be a servo valve.

The first half of the outer cylinder (1) is a first resin filling injection part, and the second half is an operating part, which is an outer cylinder part (11). The first half of the inner cylinder (2) is the second resin filling injection part, the second half is the operating part, the inner cylinder cylinder part (21) is formed on the inner circumference, and the outer circumference is for the outer cylinder. It is a piston part (22) and is slidably arranged in the outer cylinder part (11). The first half of the needle (3) is a small-diameter resin-filled injection part, and the second half is the working part, which is the inner cylinder piston part (31) and is the inner cylinder cylinder part of the inner cylinder body (2). It is slidably stored in (21).

The inner circumference of the outer cylinder (1) and the outer circumference of the inner cylinder (2) constitute a first resin passage (6), and the inner circumference of the inner cylinder (2) and the needle.
A second resin passage (7) is constituted by the outer periphery of (3). The first resin passage (6) is closed when the front end outer peripheral surface of the inner cylindrical body (2) advanced to the first resin seal (61) formed on the inner peripheral surface of the distal end portion of the outer cylindrical body (1) contacts. The second resin passage (7) is a second resin seal portion (71) formed on the inner circumference of the tip of the inner cylindrical body (2).
Then, when the tip of the advanced needle (3) is inserted, it is closed. Further, when the tip portion of the needle (3) closes the second resin passage (7), it is possible to apply a holding pressure to the resin in the mold (4) at the same time.

With the above construction, the piston (31) for the inner cylinder is operated to advance the needle (3), and the second resin seal portion (71) at the tip of the inner cylinder (2) is attached to the needle (3). Only the first resin can be injected into the mold by closing at the tip and retreating the inner cylinder (2) to open the first resin seal portion (61). Further, the inner cylinder (2) is moved forward and brought into contact with the first resin seal portion (61) of the outer cylinder (1) to close the first resin passage (6), and at the same time, the needle (3) is moved to the end. It is possible to inject only the second resin into the mold by moving the second resin in the direction to provide a gap between the tip insertion portion of the needle (3) and the second resin sealing portion (71). By the above operation, the first resin kneading supply unit (C) or the second resin kneading supply unit (D) can be switched and connected to the mold (4).

The position detection device (5a) is mounted on the exposed rear end of the needle (3) and moves with the needle (3) and is used for detecting the position of the needle (3). , Potentiometers and encoders are used. Similarly, the position detecting device (5b) is mounted on the exposed rear end portion of the inner tubular body (2), moves with the inner tubular body (2), and is used for detecting the position of the inner tubular body (2). The CPU (5) receives a signal from the position detection devices (5a) (5b) and controls the inner cylinder drive cylinder (b1) and the needle drive cylinder (b2) to produce proportional valves (51) (52). ) Or feedback control of the servo valve.

A compound injection molding machine configured as described above
In (A), as the first resin, a skin layer forming material (JS)
And a core layer forming material (JC) is used as the second resin. The skin layer forming material (JS) contains SU as fine particles that can be sintered.
A mixed material containing 60% of S fine particles and 40% of a resin binder is used, while only the same resin binder as described above is used for the core layer forming material (JC).

A resin hopper (c
In 3), the core layer forming material (JC) is charged into the resin hopper (d3), and the first resin kneading supply section (C) and the second resin kneading supply section (D)
To melt and knead the skin layer forming material (JS) and the core layer forming material (JC) respectively. The sufficiently kneaded skin layer forming material (JS) and core layer forming material (JC) pass through the connecting cylinders (c5) and (d5) respectively, and the first resin passage (6) of the resin injection device (B) and It is sent into each of the second resin passages (7).

Next, in the injection operation, first, as described above, the inner cylinder body (2) and the needle (3) are drive-adjusted to open the first resin passage (6) and the second resin passage (7). ) Is closed, and as shown schematically in FIG.
Connect (C) to the mold (4). In this state, screw (c
2) Extrude a predetermined amount of skin layer forming material (JS) into the die
(4) Inject into the inside.

Next, the inner cylindrical body (2) and the needle (3) are drive-adjusted to open the second resin passage (7) and close the first resin passage (6). As shown in Fig. 2, the second resin kneading supply part (D) is connected to the mold (4) in a communicating manner, and in this state, a predetermined amount of the core layer forming material (JC) is extruded by the screw (d2) and the mold (4) It shoots in. As a result, the previously injected skin layer forming material (JS) is spread around the inside of the mold and the core layer forming material (JC) is filled inside.

Finally, as schematically shown in FIG. 5, the first resin passage (6) is opened and a small amount of the skin layer forming material (JS) is injected to the gate portion as in the case of FIG. In this way, a sandwich molded article (M) made of a composite of the skin layer forming material (JS) and the core layer forming material (JC) can be obtained by subjecting it to predetermined molding conditions.

In the method of the present invention, the sandwich molded product (M) obtained by the above operation is subjected to heat treatment. The heating conditions at this time are selected such that the core layer forming material (JC) is volatilized and the SUS fine particles in the skin layer forming material (JS) are sintered.

In the above composite injection molding machine (A), a mold is used which can obtain a sandwich molded article (M1) having a longitudinal section as shown in FIG. 6 and a transverse section as shown in FIG.
By treating the resulting sandwich molded product (M1) under the above heating conditions, it has a vertical cross section as shown in FIG. 8 and a cross section as shown in FIG. 9, and has an outer shell (a) and a hollow part ( A hollow product (G1) consisting of (2) can be easily obtained.

Further, as another example, a mold capable of obtaining a sandwich molded article (M2) having a longitudinal section as shown in FIG. 10 and a transverse section as shown in FIG. 11 is used, and the obtained sandwich molded article (M2 ) Under the above heating conditions, a hollow product (a) having a vertical cross section as shown in FIG. 12 and a horizontal cross section as shown in FIG. 13 and comprising an outer shell (a) and a hollow portion (b) ( It can also be easily obtained with G2).

[0034]

EFFECTS OF THE INVENTION According to the present invention, a hard material such as metal or ceramic can be easily molded into a hollow product of any shape. In addition, the time required to mold the hollow product can be greatly shortened.

[Brief description of drawings]

FIG. 1 is a schematic plan view of an example of a composite injection molding machine used in the hollow product manufacturing method of the present invention.

FIG. 2 is a schematic cross-sectional view of main parts of the molding machine of FIG.

FIG. 3 is a schematic diagram illustrating the first injection of a skin layer forming material in sandwich molding.

FIG. 4 is a schematic diagram illustrating injection of a core layer forming material in sandwich molding.

FIG. 5 is a schematic diagram illustrating the final injection of the skin layer forming material in sandwich molding.

FIG. 6 is a schematic vertical cross-sectional view of a sandwich molded article as an example of the hollow article molded article of the present invention.

FIG. 7 is a schematic cross-sectional view of the sandwich molded product shown in FIG.

FIG. 8 is a schematic vertical sectional view of a hollow product obtained by sintering the sandwich molded product of FIG.

9 is a schematic cross-sectional view of the hollow product shown in FIG.

FIG. 10 is a schematic vertical cross-sectional view of a sandwich molded product of another example of the molded product for hollow articles of the present invention.

11 is a schematic cross-sectional view of the sandwich molded product shown in FIG.

12 is a schematic vertical cross-sectional view of a hollow product obtained by sintering the sandwich molded product of FIG.

13 is a schematic cross-sectional view of the hollow product shown in FIG.

[Explanation of symbols]

(A) ... Composite injection molding machine (B) ... Resin injection device (C) ... First resin kneading supply section (D) ... Second resin kneading supply section (E) ... Main drive cylinder (JS) ... Skin layer forming material (JC) ... Core layer forming material (b1) ... Inner cylinder drive cylinder (b2) ... Needle drive cylinder (c1) (d1) ... Heating cylinder (c2) (d2) ... Rotating screw (c3) (d3) ... Resin hopper (c4) (d4)… Screw drive part (c5) (d5)… Connection cylinder (1)… Outer cylinder (2)… Inner cylinder (3)… Needle (4)… Mold (5)… CPU (5a) (5b) ... Position detection device (41) ... Sprue bush (51) (52) ... Proportional valve (M1) (M2) ... Sandwich molding (G1) (G2) ... Hollow product

Claims (3)

[Claims] 1. A skin layer forming material obtained by kneading sinterable fine particles and a resin binder which can be removed by heating.
The core layer-forming material composed of the resin binder is compound-injected to form a sandwich molded article in which the core layer-forming material is coated with the skin layer-forming material, and then the sandwich molded article is heat-treated, A method for producing a hollow product, comprising removing a resin binder of a molded product and sintering sinterable fine particles in a skin layer forming material. 2. A skin layer forming material comprising a kneaded product of sinterable fine particles and a resin binder removable by heating, and a core layer forming material comprising the resin binder, wherein the core layer forming material is the above. A molded article for hollow articles, which is coated with a material for forming a skin layer and molded. 3. A hollow article obtained by the method according to claim 1.