JPH06297513A - Method and device for molding resin - Google Patents

Abstract

PURPOSE:To provide an excellent method and device for molding resin wherein the device is extremely easily constituted and a runnerless system is constituted at a low cost. CONSTITUTION:Resin is molded by sending molten resin 4 through a gate into a cavity 3 through a runner part 2 constituted of a sprue part 2A from a resin pouring part 1. In the method for molding resin, molten resin 4 is sent into the cavity 3 and a molding 8 in the cavity 3 is cured and thereafter a pushing back body 5 of resin is moved to push back an unnecessary molding being in a cured state to the resin pouring part 1. The unnecessary molding 6 is melted by heat in the resin pouring part 1 and pushed back into the resin pouring part 1 in a molten state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding method and a resin molding machine in which molten resin is fed into a cavity from a resin injection portion through a runner portion such as a spool portion or a runner portion to form a resin. is there.

[0002]

2. Description of the Related Art In conventional resin molding, an injection nozzle is provided at the tip of a cylinder, and, for example, the injection nozzle is composed of a spool portion, a runner portion, a land portion, and a gate portion. The molten resin in the cylinder is injected from the injection nozzle into the cavity through the runner, the inside of the cavity is cooled to a predetermined temperature, and the resin in the cavity is cured to form a molded product. The mold is ejected by releasing the cavity from the mold.

At this time, in the conventional method, at the same time as the molding discharge of the molded product, the unnecessary molded product called a runner that is molded in the runner is discharged.

Conventionally, since this runner is a waste of material, it is devised that the runner is crushed, mixed again with the resin virgin material, and reused in order not to waste the material.

However, such a discharge and reuse (recycling) system of the runner is very troublesome.

Therefore, a hot runner system has been developed in which the runner portion is always heated during molding, and the runner is not forced to cool and harden and the runner is not discharged.

However, since the runnerless method using the hot runner system is a method of providing a heating device in the vicinity of the cavity that should be cooled originally, a heat insulating structure has to be provided between the cavity and the method, which is extremely difficult. It is an expensive system, not a general-purpose system.

Therefore, in general, the idea that the runner is discharged and the runner is reused without waste has been the mainstream.

In view of the above situation, the present invention is completely different from the conventional one and does not rely on only a heating means such as a hot runner system and is a very simple means to prevent the runner from being discharged. A resin molding method and a resin molding machine are provided.

[0010]

The gist of the present invention will be described with reference to the accompanying drawings.

In the resin molding method in which the molten resin 4 is fed into the cavity 3 from the resin injecting portion 1 through the runner portion 2 such as the spool portion 2A and the runner portion 2B, the molten resin is injected into the cavity 3. After the resin has been fed, the resin push-back body 5 is moved toward the resin injecting section 1 to push back the melted or hardened unnecessary molded article 6 in the runner section 2 to the resin injecting section 1. It is related to the law.

Further, after the molten resin 4 is fed into the cavity 3 to cure the molded product 8 in the cavity 3, the resin push-back member 5 is moved to move the unnecessary molded product 6 in the cured state to the resin injection part 1. Push back, unnecessary molding 6 resin injection part 1
The resin molding method according to claim 1, wherein the resin is pushed back into the resin injecting portion 1 in a molten state by the heat of the above.

Further, by moving the resin push-back member 5, the gate portion 9 into the cavity 3 is formed at the side of the resin push-back member 5.
The resin injection part 1 is closed by the moving tip of the resin push-back body 5, and the resin molding method according to claim 1 or claim 2 is characterized in that.

Further, the cavity 3 is provided from the resin injection part 1 through the runner part 2 such as the spool part 2A and the runner part 2B.
In a resin molding machine in which the molten resin 4 is fed into and molded by a resin, the resin is moved toward the resin injecting section 1 and pushed back to the resin injecting section 1 in the molten or hardened unnecessary molding 6 in the runner section 2. The present invention relates to a resin molding machine in which a push-back body 5 is movably arranged in the runner section 2.

Further, after the molten resin 4 is fed into the cavity 3 to cure the molded article 8 in the cavity 3, the resin push-back body 5 is controlled to be pushed back and moved. The present invention relates to the resin molding machine.

Further, a gate closing portion 5A for closing the gate portion 9 to the cavity 3 when the resin pushing back body 5 pushes back and moves is formed on a side portion of the resin pushing back body 5.
5. An injection closing part 5B for closing the resin injection part 1 is formed at the moving front end part of the resin push-back body 5, and
Alternatively, the present invention relates to the resin molding machine according to claim 5.

A resin molding machine according to claim 6, characterized in that the resin injection part (1) is not provided with a nozzle having a small diameter and the resin injection part (1) is set to have substantially the same diameter as the spool part (2A). is there.

[0018]

After the molten resin 4 is fed into the cavity 3 from the resin injection part 1 through the runner part 2, the resin push-back body 5 moves toward the resin injection part 1 and the inside of the runner part 2 The unnecessary molded product 6 is pushed back to the resin injection part 1.

[0019]

The present embodiment belongs to any of the inventions described in claims 1 to 3, and is based on the following method.

In the resin molding method in which the molten resin 4 is fed from the resin injection section 1 into the cavity 3 via the gate section 9 via the runner section 2 consisting of the spool section 2A, the resin is melted into the cavity 3. After the resin 4 is fed by the movement of the screw 13 and the molded product 8 in the cavity 3 is cured, the resin push-back body 5 is moved to push the cured unnecessary molded product 6 back to the resin injecting portion 1, and the unnecessary molded product 6 Is pushed back into the resin injecting section 1 in a molten state by the heat in the resin injecting section 1. At this time, by moving the resin push-back body 5, the gate closing portion 5A on the side of the resin push-back body 5 closes the gate portion 9 into the cavity 3, and at the injection closing portion 5B at the moving tip of the resin push-back body 5. The resin injection part 1 is closed.

Therefore, the resin molding machine according to the present embodiment belongs to any of the inventions described in claims 4 to 7, and is specifically constructed as shown in FIGS.

In the illustrated embodiment, it can be said that only the so-called spool portion 2A is provided, and the cavities 3 are arranged on the left and right sides of the spool portion 2A.
It can be considered that the runner portion 2 that connects the cavity 3 and the cavity 3 is omitted, and the gate portion 9 and the runner portion 2B are slightly present between the spool portion 2A and the cavity 3.

Further, the resin push-back body 5 has the cavity 3
Exhaust ejector device 10 for pushing out and ejecting the molded product 8 inside
Separately from the above, a push-back ejector device 11 for pushing out and driving the resin push-back body 5 is provided, and the rod portion provided so as to be capable of protruding is used as the resin push-back body 5.

The resin push-back body 5 is constructed such that the movable tip portion closes the tip portion of the runner portion 2 before moving, and the resin push-back member after pushing back the unnecessary molding 6 in the runner portion 2 is moved. The peripheral surface of the body 5 is used as a gate closing portion 5A, and the gate closing portion 5A closes the gate portion 9 which is the injection introducing portion in the cavity 3, and the injection closing portion 5 formed at the movable tip portion.
B is configured to go straight toward the resin injection part 1 and close the resin injection part 1.

In this way, the unnecessary molded product 6 in the runner part 2 is pushed back by the movement of the resin push-back body 5, and the unnecessary molded product 6 is pushed back to the resin injection part 1 in a molten state by the heat of the resin injection part 1. The resin injection part 1 is closed.

After that, the mold 7 is released and the cavity 3 is released, and the ejection rod 10A of the ejection ejector device 10 is projectingly movable to extrude and eject the molded product 8 attached to the cavity 3.

Further, in this embodiment, there is no tapered (small diameter) injection nozzle portion as in the prior art, and the runner portion 2 (spool portion 2A) is formed with the diameter substantially the same as the diameter of the cylinder 12. The runner portion 2 and the resin injection portion 1 cannot be clearly distinguished from each other. Therefore, the spool portion has a diameter larger than that of the conventional spool portion 2A.

That is, the resin injection part 1 is closed by the injection block part 5B of the resin push-back member 5 during molding as in this embodiment, and the runner part 2 is cooled and hardened, whether it is in a semi-molten state or in a molten state. Since it can be molded, it does not require a conventional injection nozzle having a small diameter. Therefore, unlike the conventional case, there is no injection resistance due to the nozzle portion, and low-pressure injection of the molten resin is possible, so that the warpage and deformation of the molded product 8 can be reduced, and the dispersion of goodness and badness of the molded product 8 for each molding shot. The effect is also reduced.

That is, the injection blocking portion 5B of the resin push-back body 5
Since the resin injection part 1 is closed by the above, even if the resin injection part 1 and the runner part 2 have a large diameter, the resin leakage can be surely prevented, and even if the unnecessary molded product 6 in the runner part 2 has a large diameter, it is in a semi-molten state. Since there is no hindrance to the molding of the molded product 8, it is possible to design the structure that does not have the small-diameter injection nozzle portion that exhibits the excellent effect as described above.

The present invention may be applied to a structure in which the runner part 2 is composed of only the spool part 2A as shown in FIG. 4, or a structure having a runner part 2B as shown in FIG. The structure may be such that a small amount of unnecessary molded product 6 (runner) is discharged.

The present invention is not limited to this embodiment, and any structure of the resin molding machine may be applied, and the structure of the resin push-back body 5, the forming means, etc. can be designed appropriately according to this. Is.

[0032]

Since the present invention is constructed as described above, it is an excellent resin molding method and resin molding machine which can construct a runnerless system with a very simple structure at a low cost.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a configuration of this embodiment when injecting a resin.

FIG. 2 is a schematic structural cross-sectional view of the present embodiment when a resin push-back body is movable after completion of resin injection.

FIG. 3 is a schematic cross-sectional view of a configuration when a molded product is discharged according to this embodiment.

FIG. 4 is an enlarged explanatory cross-sectional view of a main part at the time of resin injection according to the present embodiment.

FIG. 5 is an enlarged explanatory cross-sectional view of a main part at the time of resin injection of another example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resin injection part 2 Runner part 3 Cavity 4 (Melting) resin 5 Resin push back body 5A Gate closing part 5B Injection closing part 6 Unnecessary molded product 8 Molded product 9 Gate part

Claims (7)

[Claims] 1. In a resin molding method in which a molten resin is fed into a cavity from a resin injecting portion through a runner portion such as a spool portion or a runner portion, and then the resin is molded, after the molten resin is fed into the cavity, A resin molding method characterized in that a resin push-back body is moved toward a resin injection part to push back an unnecessary molded product in a molten state or a cured state in the runner part to the resin injection part. 2. After the molten resin is fed into the cavity and the molded product in the cavity is cured, the resin push-back body is moved to push back the cured unnecessary product to the resin injecting section to remove the unnecessary product from the resin. The resin molding method according to claim 1, wherein the resin is pushed back into the resin injecting section in a molten state by heat in the injecting section. 3. The movement of the resin push-back body closes the gate portion into the cavity at the side portion of the resin push-back body, and closes the resin injection portion at the moving front end portion of the resin push-back body. The resin molding method according to claim 1 or claim 2. 4. A resin molding machine for feeding a molten resin into a cavity from a resin injecting section through a runner section such as a spool section or a runner section for resin molding, and moving the resin toward the resin injecting section. A resin molding machine characterized in that a resin push-back body for pushing an unnecessary molded product in a molten state or a cured state in the section to a resin injection section is movably arranged in the runner section. 5. The resin molding machine according to claim 4, wherein after the molten resin is fed into the cavity and the molded product in the cavity is cured, the resin push-back body is pushed back and moved. 6. A gate closing portion is formed on a side portion of the resin push-back body to close a gate portion to the cavity when the resin push-back body pushes back and moves, and a resin injection portion is closed at a moving tip portion of the resin push-back body. The resin molding machine according to claim 4 or 5, wherein an injection closing portion is formed. 7. The resin molding machine according to claim 6, wherein the resin injection part is not provided with a nozzle having a small diameter, and the resin injection part is set to have substantially the same diameter as the spool part.