JPH11300796A - Injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding method which can perform a satisfactory molding process without the cutting and stretching of moldings when these moldings are of a slendar shape and are parted from a die. SOLUTION: A mold member 4 is formed of plural slide templates arranged face to face in a die opening direction, and cavity parts 7-1, 7-2, 7-3 which form a molding cavity 6 by connecting the slide templates, are provided. At the same time, the molding cavity 6 is opened by the slide template 5-3 on one of the end parts and is closed by the slide template 5-1 on the other end part under the arrangement of each of the formed cavity parts 7-1, 7-2, 7-3. Further, the molding cavity 6 is filled with a molding material to be set, and each of the slide templates is slided open from a die starting with the slide template 5-1 on the other end part. Thus moldings 9 are parted from the molding cavity 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injection-molding an elongated body.

[0002]

2. Description of the Related Art Thermoplastic molding materials such as synthetic resins are molded into a wide range of materials because they are melted at a relatively low temperature and are suitable for molding into various shapes. Although there are various molding methods for such a molding material, an injection molding method is often used for manufacturing a normal molded body. Injection molding is a method in which a molding material melted by heating is injected into a molding die by an injection molding machine, the molding material is cooled and solidified in the molding die, and then released to obtain a molded product.

[0003] The injection molding method is a molding method which can cope with molding of various shapes. However, when an elongated molded article is manufactured by the injection molding method, a portion where a molding die and the molded article are in contact is long. Therefore, the resistance at the time of mold release was increased, and molding problems such as expansion and cutting of the molded body were likely to occur. For this reason, it has been necessary to set the diameter of the elongated compact to be large or to increase the draft when releasing the mold.

[0004] A molding die for an elongated injection molded article requires a cavity to be deeply machined with a small diameter, and uses a mold in which a mold portion corresponding to the original length of the product is divided so as to be easily machined. In some cases, the mold part is divided in order to change the cross-sectional area or cross-sectional shape at an intermediate position of the molded body. Such divided molds were joined during the molding process, and there was no difference in opening the molds from ordinary molds.

Further, since the cavity of a molding die for an elongated molded body has a deep shape, when the molten molding material is injected into the cavity, the air or the injected air which originally existed in the cavity was injected. There is no place to escape gas and the like generated from the molding material, and burns and bubbles may be generated on the surface of the molded body. Further, if an air vent is provided to allow air to escape, the molding material enters into the air vent at the time of filling, and becomes a burr when formed into a molded body, which is inconvenient.

As described above, conventionally, there have been some problems in producing an elongated molded article by injection molding.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above points, and does not break or stretch even when the elongated molded product is released from the mold. It is an object of the present invention to provide an injection molding method that enables air and the like in a cavity at the time of filling a molding material to escape with a mold, and that can perform satisfactory filling.

[0008]

According to the injection molding method of the present invention, a mold member 4 is formed by a plurality of slide mold plates 5-1, 5-2, 5-3 which are in contact with each other in the mold opening direction. A cavity for forming the molding cavity 6 by being connected to each of the slide mold plates 5-1, 5-2 and 5-3, and the molding cavity 6 is provided at one end of the slide mold plate 5;
-3, each cavity 7-1, 7-2, 7-3 is formed so as to be closed with the slide template 5-1 at the other end, and the molding material is filled into the molding cavity 6. After solidifying,
The molded body 9 in the molding cavity 6 is demolded by opening the molds of the slide mold plates 5-1, 5-2, and 5-3 in order from the slide mold plate 5-1 at the other end. It is characterized by the following.

[0009] The injection molding method according to claim 2 of the present application comprises:
It is characterized in that at least one of the plurality of slide mold plates is formed of a porous material.

[0010] The injection molding method according to claim 3 of the present application comprises:
It is characterized in that the slide type plate 5-3 at the one end is formed by forming a radius 8 at the opening edge of the cavity 7c.

[0011]

Embodiments of the present invention will be described below with reference to examples.

FIGS. 1 and 2 show an example of the invention according to claim 1 of the present application, in which (a) to (c) of FIG. 1 and (a) to (c) of FIG. The injection molding method of the present invention proceeds.

FIG. 1A shows a state in which the mold before the molding material is filled in the cavity 6 is closed. The molding die 1 is divided into a movable part 2 and a fixed part 3. The fixed part 3 of the molding die 1 is arranged on the side of the injection molding machine into which the molding material is injected, and the movable part 2 of the molding die 1 is arranged on the opposite side of the fixed part 3 of the molding die 1. The movable part 2 of the molding die 1 is
Is connected to a movable device operated by hydraulic pressure or the like so as to be able to approach / separate from the fixed portion 3. Further, several KO pins 10 are provided which penetrate the movable part 2 and the mold member 4 of the molding die 1 and are movable in the mold opening direction.

The mold member 4 is provided on the movable part 2.
The mold member 4 includes three slide mold plates 5-1, 5-2, 5-
Although it is divided into three, the number of slide templates is not limited, and the number can be appropriately selected according to the molded product to be obtained.

Each of the cavities 6 is also provided with a slide template 5.
-1, 5-2, and 5-3 are divided into cavities 7-1, 7b, and 7c. The cavity 7-1 of the slide template 5-1 forms the tip of the cavity 6, and has a shape with one end closed.
The cavity 7-2 of the slide mold plate 5-2 forms an intermediate portion of the cavity 6. The cavity 7-3 of the slide template 5-3 communicates with the base cavity 13 of the fixed part 3. A gate 15 connected to the runner 14 is provided above the base cavity 13.

The inner surface of the cavity 6 has a surface roughness of 0.7 s.
It is desirable to provide the following mirror finishes. Further, for the purpose of reducing the mold release resistance, it is preferable that the surface quality of the inner surface of the cavity 6 be finished in a scale shape having fine irregularities.

FIG. 1B shows a state in which a molten molding material is injected from the gate 15 of the fixed portion 3 and filled into the entire cavity 6. The molding die 1 is provided with an appropriate cooling device and the like, and is maintained at a sufficiently low temperature, so that the molding material solidifies after a while and becomes a target molded body 9.

In FIG. 1 (c), after the molding material has solidified,
Shows when the mold opening process has started. Movable part 2 and fixed part 3
The slide type plate 5-1 farthest from the joining surface of
It is fixed to. On the other hand, slide mold plates 5-2 and 5-
3 is provided with a rail or the like so as to be slidable between the movable part 2 and the movable mold 2 at this time.
Reference numeral -3 indicates that it does not interlock with the movement of the movable part 2. As the movable section 2 separates from the fixed section 3, the slide template 5-1 and the slide template 5-2 begin to separate. Then, only the leading end of the molded body 9 is released from the inside of the cavity 7-1 of the slide mold plate 5-1.

FIG. 2A shows a continuation of FIG. 1C. In FIG. 2A, the movable part 2 and the fixed part 3 of the molding die 1 are further illustrated.
Indicates when they are separated from each other. When the distance between the slide mold plate 5-1 and the slide mold plate 5-2 becomes constant, a stopper or the like operates on the slide mold plate 5-2, and the slide mold plate 5-2 also moves the movable portion 2 of the molding die 1. The slide template 5-2 and the slide template 5-3 begin to separate from each other. As a result, the intermediate portion of the molded body 9 is released from the cavity 7-2 of the slide mold plate 5-2.

FIG. 2B shows a state where the movable portion 2 and the fixed portion 3 of the molding die 1 are further separated. At this stage, a stopper or the like also operates on the slide mold plate 5-3, and all the slide mold plates 5-1, 5-2, and 5-3 move together with the movable portion 2 of the molding die 1, and the molded body 9 is released from the fixing part 3. Each slide template 5-1 and 5 when the mold is completely opened
The interval between -2 and 5-3 can be appropriately selected depending on the size of the target molded body 9.

Finally, as shown in FIG.
Is pushed out by the KO pin 10 to completely release the molded body 9 from the mold member 4.

FIG. 3 shows another example of the invention according to claim 1 of the present application.

FIG. 3A shows an example of the molding die 1 in which the mold member 4 is provided in the fixing portion 3. The movable portion has a base cavity 13, and a gate 15 connected to the runner 14 is provided above the base cavity 13. The base cavity 13 is provided with a protrusion 11 provided with an undercut. The KO pin 10 is provided with several pieces that can move in the mold opening direction so as to penetrate the movable part 2 and the mold member 4 of the molding die 1.

The molding material is filled from the gate 15 on the moving side 2 and solidified while the mold member 4 is tightened.

Next, the movable part 2 of the molding die 1 is separated from the fixed part 3. Each slide template 5-1, 5-2, 5
-3 has the same structure as that of FIG.
The operation of the slide templates 5-1, 5-2, 5-3 is the same as in the case of FIG. First, the distance between the slide template 5-1 and the slide template 5-2 is separated, and then, the distance between the slide template 5-2 and the slide template 5-3 is separated. The state shown in FIG.

Then, as shown in FIG.
Since the base cavity 13 and the molded body 9 are connected by the projection 11 provided with an undercut, the molded body 9 solidified in the cavity 6 of the mold member 4 of the fixed part 3 is 4 can be released from the mold. Finally, the molded body 9 is completely released by the KO pin 10. FIG. 4 shows another example of the embodiment of the invention according to claim 2 of the present application.

FIG. 4A shows a molding die 1 as an example. The mold member 4 of the movable part 2 of the molding die 1 is formed from three slide mold plates 5-1, 5-2, 5-3 as in FIG. The KO pin 10, the gate 15, and the like are provided as in the case of FIG. In this example, the slide mold plate 5-1 having the cavity 7-1 forming the tip of the cavity 6 is formed of a porous material, and the molten molding material is injected into the cavity 6 when the molten molding material is injected into the cavity 6. The air or gas generated from the injected molding material, which was initially present therein, is released to the outside through the porous slide template 5-1. If the surface of the molded portion filled and solidified in the hollow portion 7-1 of the slide mold plate 5-1 formed of a porous material is roughened, the surface of the tip portion of the molded body 9 is not roughened. Slide template 5-
2 or the slide type plate 5-3 may be formed of a porous material. In addition, the plurality of slide mold plates 5 can be formed of a porous material for reasons such as increasing the efficiency of degassing.

Examples of the porous material include sintered materials having various materials and densities according to the desired shape of the molded body 9.

FIG. 4B shows a molding die 1 as another example, in which a porous material plate 12 is sandwiched between two slide die plates 5-1 and 5-2. It is.
The porous material plate 12 may be a single divided member, or may be fixed to the slide template 5-1 or the slide template 5-2. A cavity 7-4 forming the portion is provided. Also in this case, FIG.
As in (a), the gas in the cavity 6 is
2 to the outside.

FIG. 5 shows another example of the embodiment of the present invention. FIG. 5 is a view showing the opening edge of the cavity 7-3 of the slide type plate 5-3 closest to the contact surface between the fixed part 3 and the movable part 2. A round 8 is provided as shown in FIG. When the target formed body is minute, the radius 8 is preferably processed by electric discharge machining, and more preferably polished thereafter. The radius dimension can be arbitrarily determined according to the diameter of the molded body.
The radius 8 may be provided on the entire circumference of the end face, or may be provided on a part thereof. By providing a radius in the above portion, bite into the edge portion due to shrinkage of the molding material is reduced,
Demolding becomes easy. In addition, since stress concentration due to edges can be avoided at the base of the obtained molded body 9, cracks and breaks can be prevented.

[0031]

As described above, according to the injection molding method of the present invention, in a molding die for injection molding divided into a movable part and a fixed part, the mold member provided in the movable part or the fixed part is opened in the mold opening direction. It is divided into a plurality of slide templates that are in contact with each other, and a molding die formed by providing a cavity part that forms a molding cavity by being connected to each slide template is used for the molding cavity. After the molding material is filled and solidified, the movable part of the molding die is separated from the fixed part of the molding die so that the movable part of the molding die is opened from the slide template far from the contact surface between the fixed part and the movable part. It is characterized by removing the molded product in the cavity for
By releasing the molded body by sequentially moving each slide template, the resistance force between each molded body applied to each of the slide template and the movable member is moved integrally. A mold that is smaller and further increases the number of slide mold plates reduces the resistance of the mold release, so that even a slender molded body can perform mold release well without cutting or stretching. It is.

The injection molding method according to the second aspect of the present invention uses a molding die in which at least one of the slide mold plates is formed of a porous material. Gas or the like generated from the molding material is released through the porous material, and it is possible to prevent burns and bubbles from being generated on the surface of the molded body.

The injection molding method according to the third aspect of the present invention uses a molding die formed by forming a radius at the opening edge of the cavity of the slide die plate closest to the contact surface between the fixed part and the movable part. The bite into the edge portion due to the shrinkage of the molding material is reduced, and the mold release is facilitated.
Since stress concentration due to the edge can be avoided at the base of the obtained molded body, cracks and breaks can be prevented, and the durability of the molded body can be improved.

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of the present invention,
(A)-(c) is sectional drawing.

FIG. 2 shows another example of the embodiment of the present invention, and (a) to (c) are cross-sectional views.

FIG. 3 shows another example of the embodiment of the present invention, and (a) and (b) are cross-sectional views.

FIG. 4 shows another example of the embodiment of the present invention, and (a) and (b) are cross-sectional views.

FIGS. 5A and 5B show another example of the embodiment of the present invention, in which FIG. 5A is a cross-sectional view and FIG.

[Explanation of symbols]

 4 Mold member 5-1 Slide mold plate 5-2 Slide mold plate 5-3 Slide mold plate 6 Cavity 7-1 Cavity 7-2 Cavity 7-3 Cavity 8R 9 Molded body

Claims (3)

[Claims] 1. A mold member is formed by a plurality of slide mold plates which are arranged in contact with each other in the mold opening direction, and a cavity is formed which is connected to each slide mold plate to form a molding cavity. Each cavity is formed so as to be opened with a slide template at one end and closed with a slide template at the other end, and a molding material is filled and solidified in a molding cavity, and then the other end is formed. By opening each slide template in order from the slide template of the part,
An injection molding method, comprising removing a molded body in a molding cavity. 2. The injection molding method according to claim 1, wherein at least one of the plurality of slide mold plates is formed of a porous material. 3. The injection molding method according to claim 1, wherein the slide mold plate at one end is formed by providing a radius at an opening edge of a cavity of the cavity.