JPH0820050A - Gate cutting method and structure of cavity in injection molding machine - Google Patents

Abstract

PURPOSE:To sufficiently apply the holding pressure due to injection pressure to the interior of a cavity until the molten resin in the cavity is almost perfectly solidified, to make molding deficiency hard to generate as compared with a conventional example and to well perform stable and highly accurate molding. CONSTITUTION:In a gate cutting method of a cavity in an injection molding machine, a passage part 7 allowing a runner part 2 and a cavity 3 to communicate each other to form a gate part 5 and a gate cutting member 6 having a gate cut-off part cutting off the gate part are provided in a freely movable manner and a sharp blade part is formed to the end part of the passage part 7 and the resin 4 of the gate part 5 is cut by the blade part by moving the gate cutting member 6 to cut off and close the gate part 5 by the gate cut-off part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate cutting method and a gate cutting structure for a cavity in an injection molding machine.

[0002]

2. Description of the Related Art Molten resin is injected into a cavity from a resin injection section through a sprue section, a runner section, and a runner section, and a gate section serving as an injection port. When the resin is pressure-solidified and molded into a resin, the molten resin is injected into the cavity and then the gate is blocked to close the cavity, but in the past, a stick-shaped gate cut pin was simply projected into the gate to project. It blocks the gate and closes the cavity.

In the conventional gate cutting method and gate cutting structure for a cavity in an injection molding machine, since the gate is cut off simply by the protrusion of the gate cutting pin, the runner portion is inserted into the cavity through the gate portion. After injecting the molten resin, the gate cut pin is projected in a molten state or a semi-molten state where the resin is not yet solidified to block and block the gate portion. That is, after the resin in the gate has completely solidified, even if the gate cut pin is simply pushed out, the resin in the gate does not firmly stick out and cannot be cut off.Therefore, in the past, the gate cut pin was ejected before solidification. It was shut off.

Therefore, originally, until the molten resin in the cavity is completely solidified, the molten resin in the cavity is solidified by holding the molten resin in the cavity with the injection injection pressure of the resin injection portion without blocking the gate portion. However, since it shuts off the gate portion before the resin in the gate portion solidifies, the molten resin 4 in the cavity, which takes more time to solidify than the gate portion, does not yet solidify sufficiently. At the stage, the gate part is cut off and the holding pressure by the injection injection pressure of the resin injection part is released.

For this reason, there is a problem that molding cannot be mass-produced with high precision and good accuracy because molding is not stable due to insufficient molding holding pressure and molding failure.

The applicant has also developed a structure for directly holding the cavity in order to sufficiently carry out the holding pressure (Japanese Patent Application No. 5-186222). It does not have a pressure structure, and it can give a sufficient holding pressure by injection injection pressure until the molten resin in the cavity is almost completely solidified. As compared with the conventional example, molding failure is less likely to occur and stable and highly accurate. An object of the present invention is to provide a gate cutting method and a gate cutting structure for a cavity in an excellent injection molding machine capable of performing excellent molding.

[0007]

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

The molten resin 4 is injected into the cavity 3 from the resin injection section 1 through the sprue section 2A, runner section 2B and other runner sections 2 through a gate section 5 serving as an injection port. A method of gate cutting a cavity in an injection molding machine, which comprises: injecting a molten resin 4 into a cavity 3 and blocking the gate portion 5 by a gate cut body 6 to close the cavity 3 when the resin is molded by pressure-holding solidification. A movably provided gate cut body 6 having a passage passage portion 7 that communicates the runner portion 2 and the cavity 3 to form the gate portion 5 and a gate shutoff portion 8 that shuts off the passage portion 7. A sharp blade portion 9 is formed at the end of the passage portion 7, and the gate cutting body 6 is moved to cut the resin 4 of the gate portion 5 by the blade portion 9, and the gate blocking portion 8 cuts the gate portion 5. Shut off Those of the gate cut method of cavities in an injection molding machine, characterized by.

Further, the resin 4 melted in the cavity 3
2. The resin 4 of the solidified gate portion 5 is cut by the blade portion 9 after injecting and solidifying under pressure, and the gate portion 5 is blocked and blocked by the gate blocking portion 8. The present invention relates to a cavity gate cutting method in an injection molding machine.

Further, the gate cut body 6 is constructed so as to be rotatable and movable, and the cut-out groove-like passageway portion 7 is formed in the periphery of the rotary disk-shaped gate cut body 6, and the portion other than this groove is formed. Is used as a gate cutoff portion 8, and the gate cut body 6 is pivotally moved to cut the resin 4 of the gate portion 5 by a sharp blade portion 9 formed on the cut edge of the passageway portion 7, and the gate cutoff portion 8 is used as a gate. The part 5 is blocked and closed, and
The present invention relates to a method of gate cutting a cavity in an injection molding machine according to any one of 2 above.

A molded product molded in the cavity 3
The gate cut of the cavity in the injection molding machine according to claim 3, wherein the forward / backward drive rod portion (12) of the discharge ejector rod (11) for ejecting and ejecting (10) is pivotally moved to pivotally move the gate cut body (6). It relates to the method.

In addition, from the resin injection section 1 to the sprue section 2A,
When the molten resin 4 is injected into the cavity 3 from the gate portion 5 serving as an injection port through the runner portion 2 such as the runner portion 2B, and the molten resin 4 is pressure-solidified and resin-molded,
In the gate cut structure of the cavity in the injection molding machine in which the gate cut body 6 that blocks the gate portion 5 and closes the cavity 3 after the molten resin 4 is injected into the cavity 3 is movably provided, the runner portion is provided. 2 and the cavity 3 are communicated with each other to form the gate 5 and a passage 7
By movably providing a gate cut body 6 having a gate cut-off portion 8 that cuts off the cut-off portion, a sharp blade portion 9 is formed at the end of the passage 7 and the gate cut body 6 is moved. A gate cut structure of a cavity in an injection molding machine, characterized in that the blade portion 9 cuts the resin 4 of the gate portion 5 and the gate blocking portion 8 blocks and closes the gate portion 5. is there.

The gate cut body 6 is constructed so as to be rotatable, and the groove-shaped passage 7 is formed in the periphery of the rotary disk-shaped gate cut body 6, and the portion other than this groove is gated. A cutoff portion 8 is provided, and a sharp blade portion 9 is provided on the cut edge of the passageway portion 7.
The present invention relates to the cavity gate cut structure in the injection molding machine according to claim 5.

A molded product molded in the cavity 3
A forward / backward drive rod portion 12 of a discharge ejector rod 11 for ejecting and ejecting 10 is configured to be rotatable, and when the forward / backward drive rod 12 is rotationally moved, the gate cut body 6 is rotationally moved. 7. The method according to claim 6, wherein
The present invention relates to a cavity gate cut structure in the injection molding machine described.

[0015]

The molten resin 4 is poured into the cavity 3 from the runner 2 through the passage 7 forming the gate 5.

When the gate cut body 6 is moved after the predetermined amount of the molten resin 4 is injected into the cavity 3, the resin 4 of the gate portion 5 is removed by the sharp blade portion 9 at the end of the passageway portion 7. The gate part 5 is cut off and the gate part 5 is cut off by the gate blocking part 8 of the gate cut body 6, and the cavity 3 is closed.

After injecting the passage 7 into the cavity 3 after this gate cut is not performed until the resin is completely solidified, a sufficient holding pressure than the injection injection pressure of the resin injection portion 1 is applied until then. After that, gate cutting can be performed. That is, even if the resin in the gate portion 5 is solidified and hard, it can be cut by the blade portion 9 to cut the gate. Therefore, the holding pressure due to the injection pressure can be sufficiently given as compared with the conventional example.

[0018]

EXAMPLE This example is based on the following method.

After the molten resin 4 is injected into the cavity 3 and solidified under pressure, the solidified resin 4 of the gate portion 5 is cut by the blade portion 9 and the gate portion 5 is cut off by the gate blocking portion 8. Block.

Based on this method, the present apparatus is constructed as shown below.

The gate cut body 6 is formed in a rotary disc shape so as to be rotatable and movable, and the peripheral portion of the gate cut body 6 is formed in a ridge shape that engages with the gate portion 5. In the example, a ring plate shape is used, and a groove-shaped gate passage 7 is formed in the plate-shaped peripheral ridge, and the groove-shaped gate passage portion 7 other than this groove is used as a gate blocking portion 8.

In this embodiment, the gate passage portion 7 is formed at two opposite positions because the sprue portion 2A branches the runner portion 2B left and right to form the cavities 3 respectively. .

Further, a sharp blade portion 9 is formed at the end of the passage portion 7 and the gate cut body 6 is moved to harden the resin 4 of the gate portion 5 by the blade portion 9. Even if it is cut off, the gate blocker 8 is configured to block and block the gate part 5.

A molded product molded in the cavity 3
The advancing / retreating drive rod portion 12 of the ejecting ejector rod 11 for ejecting 10 to eject is configured to be rotatable, and when the advancing / retreating drive rod portion 12 is pivotally moved, the gate cut body 6
Is configured to rotate.

Therefore, this embodiment operates as follows.

As shown in FIG. 1, the molten resin 4 injected from the resin injecting section 1 passes through the sprue section 2A and the runner section 2B branching from the sprue section 2A to the left and right, and the gate passage section forming the gate section 5 is formed. It is injected into each cavity 3 through 7. After injecting a predetermined amount of the molten resin 4 into the cavity 3, the molten resin 4 in the cavity 3 is cooled and solidified while holding pressure is applied to the molten resin 4 in the cavity 3 by injection injection pressure from the resin injecting section 1 to form a molded product 10.

Thereafter, after the unnecessary molded product 17 in the sprue portion 2A is pushed back into the resin injection portion 1 by the resin push-back pin 13 described later, the resin push-back pin 13 is once returned and the gate cut body 6 is rotated. The resin 4 of the gate 5 is cut by the sharp blade 9 at the end of the passage 7 and the gate 5 is cut off by the gate cutoff 8 of the gate cut body 6 to close the cavity 3. To do.

Thereafter, the mold is released, and the ejection ejector rod 11 is ejected and moved by advancing the advancing / retreating drive rod portion 12 to eject the molded product 10 from the cavity 3 by demolding.

In this embodiment, a moving plate 14 for moving the discharge ejector rod 11 is provided with an advancing / retreating drive rod portion 12 for sliding the moving plate 14 forward and backward, while the advancing / retreating drive rod portion 12 penetrates the moving plate 14. A through hole 15 that can be formed, and a shutter structure is provided in the through hole 15.
When the shutter is closed, the forward / backward drive rod 12 moves
14 ejects the ejector rod 11 to push it out, and when the shutter is opened, the moving plate 14 moves the rod back and forth 12
Are configured to project through and push the resin push-back pin 13.

The advancing / retreating drive rod portion 12 for advancing / retreating is configured to be rotatable, and the rotating plate 16 can be connected to the advancing / retreating drive rod portion 12 protruding through the moving plate 14. The gate cut body 6 is connected to the rotary plate 16 via a connecting pin 20, and the advancing / retreating drive rod portion 12 is rotated so that the gate cut body 6 is rotationally moved via the rotary plate 16. Is configured.

Therefore, in the present embodiment, the operation of the gate cut body 6 as described above causes the resin push-back pin 13 and the discharge ejector rod 11 to move back and forth, and the forward / backward drive rod portion 12 is controlled to move forward and backward. The present invention can be realized only by controlling the rotation of 12.

In the inventions of claims 1, 2 and 5, the gate cut body 6 is formed into a rod-shaped pin shape as in the conventional case instead of the disk shape or the ring plate shape. The gate passage 7 may be opened, and the blade 9 may be formed at the edge of the opening. Further, in this embodiment, the inside of the sprue portion 2A is advanced toward the resin injection portion 1 (nozzle portion) at the tip of the advancing / retreating drive rod portion 12, and the unnecessary molded product 17 (sprue runner) in the sprue portion 2A is moved into the nozzle portion. A resin push-back pin 13 that pushes back in a molten state by heat of the nozzle is provided.

The sprueless method in which the sprue runner is pushed back to the resin injection section 1 (nozzle section) before the mold is opened is a molding method invented by the applicant. (Japanese Patent Application No. 5-847
No. 32, Japanese Patent Application No. 6-4103, etc.) That is, the runner portion 2B is inserted from the resin injection portion 1 (nozzle portion) through the sprue portion 2A into the left and right cavity portions 3 thereof.
In the resin molding method in which the molten resin 4 is sent through and solidified and molded, the molten resin 4 is sent into the cavity 3 by the movement of the screw to solidify the molded product 10 in the cavity 3 and then the resin push-back pin Move 13
The unnecessary molded product 17 (sprue runner) in the cured state is pushed back to the resin injection unit 1, and the unnecessary molded product is pushed back into the resin injection unit 1 in the molten state by the heat in the resin injection unit 1. At this time, by moving the resin push-back pin 13, the side portion of the resin push-back pin 13 closes the runner portion 2B into the cavity portion 3,
The moving tip of the resin push-back pin 13 is inserted into the resin injection part 1 to close the resin injection part 1.

The push-back rod 13 causes the sprue portion 2
By pushing back the unnecessary molded product 17 of A, the sprueless product can be molded and discharged, and the resin material can be saved. Further, the tip of the push-back rod 13 can be used to close the nozzle portion, and even if the nozzle portion and the sprue portion 2A are designed to have a large diameter, resin leakage can be reliably prevented, and the sprue portion 2A
Is a resin with a large diameter in the sprue part 2A (unnecessary molded product 17)
Even if it is in a semi-molten state, there is no hindrance to the molded product 10, and since a small diameter nozzle is not required, injection resistance is low and low-pressure injection is possible, so warpage and deformation can be reduced, and the molded product 10 for each shot can be reduced. It is excellent because it can reduce the difference between good and bad.

In this embodiment, the push-back rod 13
Then, the unnecessary molded product 17 in the sprue portion 2A is pushed back, and the push-in rod 13 is plugged and closed by the injection plug mechanism (Japanese Patent Application No. 6-119077) provided in the resin injection part 1 (not shown). By returning to the original position again, a space 22 is formed in the sprue portion 2A, and this space is used as a resin escape space 22 at the time of gate cutting. Therefore, by ensuring this escape space 22, it is possible to cut the gate with the solidified resin. Securing the resin escape space 22 at the time of this gate cutting is an important problem in practical use. In this embodiment, the resin in the sprue portion 2A is pushed back and secured by adopting the above-mentioned sprueless method. .

Further, in the figure, reference numeral 18 is a runner discharging ejector pin for ejecting and discharging the unnecessary molded product 21 in the runner portion 2B, and 19 is a moving plate thereof.

[0037]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, the holding pressure due to injection injection pressure can be sufficiently given until the molten resin in the cavity is almost completely solidified, and molding is performed as compared with the conventional example. (EN) A gate cut method and a gate cut structure for a cavity in an excellent injection molding machine capable of performing stable, high-accuracy and good molding in which defects are unlikely to occur.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view at the time of resin injection according to this embodiment.

FIG. 2 is an explanatory sectional view of the resin push-back pin push-back operation after resin injection according to the present embodiment.

FIG. 3 is a gate cut of this embodiment (cutting off the gate portion).
It is an explanatory sectional view at the time.

FIG. 4 is a gate cut of this embodiment (cutting off the gate portion).
FIG.

FIG. 5 is an explanatory perspective view of a gate cut body according to the present embodiment.

FIG. 6 is an explanatory cross-sectional view at the time of mold release of the present embodiment.

[Explanation of symbols]

 1 Resin injection part 2 Runner part 2A Sprue part 2B Runner part 3 Cavity 4 Molten resin 5 Gate part 6 Gate cut body 7 Gate passage part 8 Gate blocking part 9 Blade part 10 Molded product 11 Discharge ejector rod 12 For forward / backward drive Rod part

Claims (7)

[Claims] 1. A molten resin is injected into a cavity from a resin injection section through a sprue section, a runner section, and other runner sections to a cavity serving as an injection port, and the molten resin is pressure-solidified to form a resin. At the time of molding, in the gate cutting method of the cavity in the injection molding machine in which the gate portion is blocked by the gate cut body after pouring the molten resin into the cavity, the runner portion and the cavity are A passageway portion communicating with each other to form the gate portion;
A gate cut body having a gate cutoff portion for blocking this is provided movably, a sharp blade portion is formed at the end of the passageway portion, and the gate cut portion is moved by this blade portion by moving the gate cut body. A method of cutting a gate of a cavity in an injection molding machine, which comprises cutting a resin and blocking and closing the gate portion by a gate blocking portion. 2. The molten resin is injected into the cavity to be solidified under pressure, and then the solidified resin of the gate portion is cut by the blade portion and the gate portion is blocked and blocked by the gate blocking portion. A method of gate cutting a cavity in an injection molding machine according to claim 1. 3. A gate cut body is configured to be rotatable and movable, the groove-shaped cut-out passage portion is formed in the periphery of the rotary disk-shaped gate cut body, and a portion other than the groove is gate-blocked. The gate cut body is pivotally moved to cut the resin of the gate portion by the sharp blade portion formed on the cut edge of the passageway portion, and the gate blocking portion blocks and blocks the gate portion. A gate cutting method for a cavity in an injection molding machine according to claim 1. 4. The gate cut body is pivotally moved by pivotally moving the advancing / retreating drive rod portion of the ejection ejector rod for ejecting and ejecting a molded product molded in the cavity. Gate cutting method for cavity in injection molding machine. 5. The molten resin is injected into the cavity from the resin injection section through the sprue section, runner section, and other runner sections, and into the cavity from the gate section that serves as an injection port. When molding, in the gate cut structure of the cavity in the injection molding machine in which the gate cut body that blocks the gate portion and closes the cavity after the molten resin is injected into the cavity is movably provided, A movably provided gate cut body having a passage passage portion which communicates with the cavity to form the gate portion and a gate interruption portion which intercepts the passage portion, and a sharp blade portion at an end of the passage passage portion. And a gate cut body is moved to cut the resin of the gate portion by the blade portion and the gate blocking portion blocks and blocks the gate portion. Gate cut structure of the cavity. 6. A gate cut body is rotatably movable, the cut groove-shaped passageway portion is formed in the periphery of the rotary disk-shaped gate cut body, and a portion other than the groove is gate-blocked. The gate cut structure of a cavity in an injection molding machine according to claim 5, wherein a sharp blade portion is formed at a cut edge of the passage portion. 7. A gate cut body, wherein an advancing / retreating drive rod portion of an ejecting ejector rod for ejecting and ejecting a molded product formed in a cavity is configured to be rotatable, and when the advancing / retreating drive rod is pivotally moved. 7. The cavity gate cut structure in an injection molding machine according to claim 6, wherein the structure is configured to rotate.