JPH0219772B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a method for molding a synthetic resin body and a mold for molding synthetic resin used in this method, and its purpose is to mold a synthetic resin body using upper and lower molds. A method for molding a synthetic resin body that does not leave marks of spouting ports of molten synthetic resin on the synthetic resin body during molding, and has no uneven grains caused by uneven temperature of a mold during molding, and a synthetic resin used in this method. Providing molds for molding.

In this specification, unevenness refers to unevenness in the uneven pattern on the surface of a synthetic resin body, and the transfer rate at high temperature parts such as jet ports is different from that in other parts, and the finish is not consistent with the shape of the uneven pattern on the surface of the mold. It refers to unevenness that occurs without

(Prior art) In recent years, synthetic resins have been developed in which upper and lower molds of a top and bottom separation type are used, molten synthetic resin is supplied into the lower mold, and then the upper and lower molds are immediately clamped to pressure mold the molten synthetic resin. A pressure molding method for the body has been proposed.

In this pressure molding method, the molten synthetic resin was supplied by the method shown in FIG.

Figure 8 shows a passage device 20 for the molten synthetic resin in the lower mold.
FIG.

In FIG. 8, 21 is a lower mold, 22 is an introduction hole plate, and 23 is an introduction hole.

The terminal end 24 of the introduction hole 23 is connected to the injection hole 2 of the lower mold 21.
It is connected to 5.

26 is a heater that heats the introduction port 23 and the introduction hole 25, and 27 is a heat insulating material.

Reference numeral 28 denotes a driving device for driving the needle valve 29 in the direction of arrow A, and FIG. 8 shows a state in which the needle valve 29 is lowered and the spout 30 is open.

In this conventional pressure molding method, the passage device 20 is maintained at about 220°C using a heater 26, and the lower mold 21 is maintained at about 30°C to 90°C, and the molten synthetic resin is poured onto the lower mold 21. and then molded.

(Problems to be Solved by the Invention) Such conventional pressure molding methods have the following problems.

Traces of the spout 30 always remain on the synthetic resin body, which requires work and effort to remove these traces from the synthetic resin body.

Further, the temperature of the passage device 20 is about 220°C, and
Since the temperature of the lower mold 21 is between 30°C and 90°C, when the molten synthetic resin hardens, unevenness in the temperature causes unevenness in the molded synthetic resin body, which deteriorates the appearance (in some cases, it may be difficult to use) Not only was the material unsuitable for use in the heat treatment, but also excessive residual stress was generated.

In addition, there is a mold disclosed in Japanese Utility Model Application Publication No. 12423/1983 as a synthetic resin molding mold that does not leave any spout marks on the synthetic resin body and does not generate residual stress.
In this mold, a supply passage for the molten plastic resin and a molding die are integrally molded, and a means for heating the molten plastic resin in the supply passage is not provided.

For this reason, it is difficult to feed the molten synthetic resin into the mold in a molten state, and the molten synthetic resin may harden within the supply passage.
It was impossible to put it to practical use.

(Means for Solving the Problems) The present invention provides an upper mold, a lower mold, and a sliding member that can freely slide up and down on the peripheral surface of at least one of the upper mold or the lower mold. Using a movable mold, the passage of the passage device provided in the sliding mold is heated in advance, and the parts other than this passage device are insulated, and the molten synthetic resin is completely clamped into the upper and lower molds. Molding of a synthetic resin body, characterized in that the passage device is used to supply the resin into the cavities of the upper and lower molds, and when the upper and lower molds are completely clamped, the spout of the passage device faces the outside of the synthetic resin body. A method and an upper mold, a lower mold, a sliding mold that can freely slide up and down on the circumferential surface of at least one of the upper mold or the lower mold, and sliding the sliding mold. A passage device for molten synthetic resin is provided only in the sliding mold, and this passage device includes a spout, a heater provided on the outer periphery of the passage, and a heat insulating device provided outside the heater. The above-mentioned problems can be solved by a mold for molding a synthetic resin, characterized in that the spout port faces the outside of the synthetic resin body when the upper mold and the lower mold are completely clamped. Solve.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is an explanatory side view of the mold according to this embodiment,
FIG. 2 is a sectional view taken along line A--A in FIG. 1.

3, 5, and 7 are a partially omitted sectional view of FIG. 1, and a 4th
The figure is a partially enlarged view of FIG. 3.

In the drawings, 1 is the upper mold, 2 is the lower mold, 3 is the sliding surface of the lower mold 2, 4 is the sliding mold, and 5 is the sliding mold 4.
6 is a telescopic device that slides the upper mold 1 and the lower mold 2.
A synthetic resin molding mold of a vertically separated type consisting of a sliding mold 4 and an expansion/contraction device 5; 7 is a passage device for molten synthetic resin.

The passage device 7 is shown in FIGS. 2, 3, 5, and 6.
In FIG. 7, it is shown in a simplified manner.

In the embodiment described below, the sliding mold 4 is provided in the lower mold 2, but even if the sliding mold 4 is provided in the upper mold 1, the same operation and effect can be obtained.

The sliding mold 4 has a passage device 7 for molten synthetic resin, and a flexible tube 8 is connected to the molten plastic resin supply side of the passage device 7 through a joint 8a with a pressure-resistant structure.

The flexible tube 8 has pressure resistance and heat resistance, and has a reinforcing layer of stainless steel wire around the outer periphery of the fluorine-based synthetic resin tube (not shown; manufactured by Yokohama Rubber Co., Ltd.).
Co., Ltd.) equipped with heat insulating material and a heat insulating mechanism can be suitably used.

The sliding mold 4 is vertically slidable along the entire circumference of the lower mold 2.

In addition to the known hydraulic press cushion, a steel spring, a urethane spring, a hydraulic cylinder, an air cylinder, etc. can be used as the expansion/contraction device 5.

As shown in FIG. 4, the passage device 7 has a spout 9,
A passage 10 communicating with this spout 9 and the passage 1
It consists of an electric heater 11 that is provided on the outer periphery of the air outlet 9 and heats the jet nozzle 9 and the passage 10, and a heat insulating material 12 such as asbestos that is provided outside the electric heater 11.

The spout 9 is arranged so as to face the sliding surface 3 of the lower mold 2 when the upper mold 1 and the lower mold 2 are completely clamped.

The heat insulating material 12 is used to maintain the spout 9 and the passage 10 at a required temperature and to prevent the temperature from being conducted to other parts of the synthetic resin mold 6 .

Using the synthetic resin molding die 6 having such a configuration, a synthetic resin body is molded through the following steps 1 to 4.

1 Preliminarily maintain the passage device 7 at approximately 220°C, and the upper mold 1, the sliding mold 4 other than the passage device 7 , and the lower mold 2 at approximately 30°C to 90°C. The temperatures of molds 1, 2, and 4 may be set arbitrarily according to the characteristics of the synthetic resin.
(see figure).

2. When the synthetic resin molding mold 6 is clamped in the required manner and with the required force, the upper mold 1 comes into contact with the sliding mold 4.

After this contact, until the mold clamping of the synthetic resin molding die 6 is completed, the required amount of molten synthetic resin 13 is passed from the passage device 7 through the spout 9 to the cavity 6a of the synthetic resin molding die 6. (5th
(see figure).

In the state shown in Figure 5, the synthetic resin molding die 6 may be stopped and the molten synthetic resin 13 may be supplied, or the molten synthetic resin 13 may be supplied while the synthetic resin molding die 6 is clamped. It's okay.

3 When the synthetic resin molding mold 6 is further clamped, the sliding mold 4 slides onto the lower mold 2, and the synthetic resin molding mold 6 is completely clamped, and at this time, the spout 9 is opened outside the synthetic resin body. , that is, facing the sliding surface 3 of the lower mold 2 (see FIG. 6).

At this time, the entire surface of the molten synthetic resin 13 comes into contact with the sliding mold 4, the upper mold 1, and the lower mold 2, except for the passage device 7, at substantially the same temperature.

However, the parts other than the passage device 7 are covered with heat insulating material 12.
Since it is insulated by , high temperature is not conducted to the molten synthetic resin 13 even when the mold clamping is completed.

4 After the molten synthetic resin 13 has hardened, when the clamping force of the synthetic resin mold 6 is removed, the upper mold 1 is separated from the lower mold 2 and the sliding mold 4, and at the same time the sliding mold 4 automatically slides onto the lower mold 2 by the reaction force of the expansion/contraction device 5 (see FIG. 7).

It goes without saying that the reaction force of the expansion and contraction device 5 is smaller than the mold clamping force, and that the clamping direction of the synthetic resin mold 6 and the sliding direction of the sliding mold 4 are the same.

Thereafter, the synthetic resin body 14 is taken out from the synthetic resin molding die 6 using a required method.

In this invention, the shape of the sliding mold 4 is not limited to the shape of the embodiment, and may be a discontinuous (not frame-shaped) sliding mold.
1 and a heat insulating material 12, the spout 9 faces the cavity 6a when the molten synthetic resin 13 is spouted, and faces the sliding surface 3 of the lower mold 2 when the mold clamping is completed.
Alternatively, the structure may be such that it faces that of the upper mold 1.

In the present invention, the timing of ejection of the molten synthetic resin 13 is not necessarily limited to the embodiment, and depending on the shape of the synthetic resin molding die 6 , the ejection may be made in the state shown in FIG. 3 of the embodiment.

In this invention, the passage device 7 is not limited to the illustrated embodiment, and may have a needle valve 25 etc., for example, as in the conventional example shown in FIG . You can set it accordingly. Furthermore, in order to create a structure in which no valve is provided in the passage device 7 as in the embodiment, it is necessary to provide a separate valve in the supply device (not shown) for the molten synthetic resin 13 or to prevent pressurization. It goes without saying that there is.

This structure without a valve reduces the number of parts and simplifies the structure.

(Effects of the Invention) As detailed above, in the method for molding a synthetic resin body according to the present invention and the mold for molding synthetic resin used in this method, when the mold for molding synthetic resin is completely clamped, the spout is closed. Since it is designed to face the outside of the synthetic resin body, the following effects are achieved.

In other words, the marks of the spout do not remain on the synthetic resin body, or even if they do, they occur only on the burrs of the synthetic resin body, so the work and effort of removing the traces of the spout from the synthetic resin body becomes unnecessary. (The traces of the spout can be removed at the same time as the burrs are removed.) In addition, the passage device that maintains the high temperature does not come into contact with the molten plastic when it hardens, which means that the molten plastic does not harden. Since the outer surface of the molten synthetic resin is cooled substantially uniformly, the molded synthetic resin body is not unevenly embossed, and no excessive residual stress is generated.

Furthermore, since a heater is provided on the outer periphery of the passage device and a heat insulating material is provided on the outside of this heater, only the molten synthetic resin passing through the passage can be heated to a predetermined temperature. , the high temperature within this passage is not conducted to the outside of the passage device.

[Brief explanation of drawings]

1 to 7 are diagrams for explaining the method or synthetic resin molding mold according to the present invention, and FIG.
The figure is a side view of the mold, Figure 2 is a cross-sectional view taken along line A-A in Figure 1, Figure 3 is a cross-sectional view of step 1, Figure 4 is a partially enlarged view of Figure 3, and Figure 5 is a cross-sectional view of Figure 1. FIG. 6 is a sectional view of step 2, FIG. 6 is a sectional view of step 3, and FIG. 7 is a sectional view of step 4. FIG. 8 is a diagram illustrating a passage device for molten synthetic resin in a conventional lower mold. 1... Upper mold, 2... Lower mold, 3... Sliding surface,
4... Sliding mold, 5... Expanding device, 6 ... Synthetic resin molding mold, 7 ... Passage device, 9... Spout nozzle,
10... Passageway, 11... Electric heater, 12... Heat insulating material, 13... Molten synthetic resin, 14... Synthetic resin body.

Claims (1)

[Scope of Claims] 1. Using an upper mold, a lower mold, and a sliding mold that can slide vertically on the circumferential surface of at least one of the upper mold and the lower mold. , the passage of the passage device provided in the sliding mold is heated in advance, the parts other than the passage device are insulated, and the molten plastic is heated through the passage device before the mold clamping of the upper and lower molds is completed. A method for molding a synthetic resin body, characterized in that the passage device is supplied into cavities of the upper and lower molds, and when the upper and lower molds are completely clamped, the spout of the passage device faces the outside of the synthetic resin body. 2. An upper mold, a lower mold, and a sliding mold that can freely slide up and down on the circumferential surface of at least one of the upper mold or the lower mold, and this sliding mold is made to slide. A passage device for molten synthetic resin is provided only in the sliding mold, and this passage device includes a spout, a heater provided on the outer periphery of the passage, and a heat insulating material provided outside the heater. and
A mold for molding a synthetic resin, wherein the spout port faces the outside of the synthetic resin body when the upper mold and the lower mold are completely clamped.