JPH07266379A - Hot runner type mold, hot runner valve to be used for that mold, and injection molding method for which such a hot runner type mold is used - Google Patents

Abstract

PURPOSE:To provide a hot runner type mold wherein pressurizing force is applied efficiently to a resin material filled into a molding cavity and generation of a short shot in a molded product is prevented. CONSTITUTION:In a hot runner type mold possessing a resin flow path 18 comprised of a sprue 34, runners 36, 52 and a gate 50, a flow path intercepting device 70 cutting the resin flow path 18 apart into a sprue 34 side and gate 50 side is provided and while a pressurizing device 70 pressurizing a molten resin material on the inside of the resin flow path 18 which is on a gate 50 side cut apart by the flow path intercepting device 70 is provided, valve device 74 opening or closing the gate 50 is provided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hot runner type mold used for resin injection molding, a hot runner valve used therefor, and an injection molding method using the hot runner type mold.

[0002]

2. Description of the Related Art Conventionally, it has been known that in injection molding a comb, if the resin injection pressure is not set high, the resin material does not reach the tips of the teeth and a short shot occurs. The number of injection-molded products, which are smaller than combs and require higher molding precision, such as small connectors and sockets having a large number of connection pin storage holes for microcomputer boards, is increasing. Short shots have become a major problem in the injection-molded products.

In reality, in the connectors and sockets for microcomputer boards, some defective products due to short shots are always mixed in the molded products, and these short shots depend on the molding conditions. Judgment is extremely difficult, and even if stable molding is performed, it suddenly occurs due to a slight disturbance that cannot be measured from the outside, so it is necessary to confirm it with the naked eye when shipping the product, which is inefficient due to human labor. There was a problem.

In order to suppress molding defects due to such short shots, it is considered effective to set the resin temperature and the mold temperature higher than that for molding a comb or the like. Increasing the temperature causes problems such as deterioration of the resin and is not realistic. It is also considered that setting the injection pressure of the resin material to a higher level will be effective in preventing short shots.
Even if the injection pressure is increased, it is difficult to effectively exert pressure on the resin material filled in the molding cavity due to the pressure loss in the resin flow path in the mold, and a satisfactory injection pressure can be applied to the resin material in the molding cavity. In order to exert such a problem, the size of the injection device becomes large, which is not realistic.

[0005]

The present invention has been made in view of the circumstances as described above, and the problem to be solved is to fill a molding cavity without increasing the size of an injection device. The hot runner type mold, the hot runner valve used for the mold, and the hot runner type mold, which can efficiently apply pressure to the resin material and reduce or prevent the occurrence of short shots in the molded product. It is to provide an injection molding method used.

[0006]

In order to achieve such a subject, the present invention has a resin flow path including a sprue, a runner, and a gate for guiding a molten resin material supplied from an injection device to a molding cavity, and the runner portion is provided. In a hot runner type mold provided with heating means for heating, a flow path blocking means for dividing the resin flow path into a sprue side and a gate side is provided, and a gate side resin flow path divided by the flow path blocking means. It is characterized in that the pressurizing means for pressurizing the molten resin material therein is provided, while the valve means for opening and closing the gate is provided.

In the hot runner type mold, for example, the sprue side runner connected to the sprue is opened to communicate with the peripheral wall surface of the gate side runner connected to the gate, while the circumference of the gate side runner is connected. By covering the opening of the sprue-side runner provided on the wall surface and separating the gate-side runner and the sprue-side runner from each other, the flow-path blocking means is fitted into the gate-side runner and pushed toward the gate side. It can be constituted by providing a pressurizing means capable of pressurizing the molten resin material in the gate-side runner and a valve means capable of being inserted into the gate and closing the gate.

Furthermore, in such a hot runner type mold, the flow path blocking means and the pressurizing means are constituted by, for example, a first valve body slidably fitted in the gate side runner, and the valve means. Can be constituted by, for example, a second valve body that is slidably arranged so as to penetrate the first valve body in the axial direction.

Further, in the hot runner type mold having the structure according to the present invention, a plurality of runners and gates can be provided in a form branched from the sprue.

Further, in the hot runner type mold having the structure according to the present invention, it is possible to form a temperature control refrigerant passage around the molding cavity.

In the hot runner mold having the structure according to the present invention, the runner may be formed of a member different from the molding cavity, and a heat insulating member may be interposed between the two members.

On the other hand, according to the present invention, a linear runner portion having a gate formed at the tip opening portion is formed, and a resin inflow port is formed on the peripheral wall surface of the runner portion.
By the first valve element arranged slidably in the runner portion in the axial direction, the resin inlet can be communicated / blocked, and the first valve element is pushed toward the gate side. While the runner portion is pressurizable, the second valve body is slidably arranged so as to penetrate through the first valve body in the axial direction, and the gate is opened and closed by the second valve body. The hot runner valve used in the enabled hot runner mold is also a feature.

Further, in such a hot runner valve, the first valve body is reciprocally driven in the axial direction to connect / disconnect the resin inflow port, and at the same time, a first drive force is exerted on the runner portion. Means and second driving means for opening and closing the gate by reciprocally driving the second valve element in the axial direction can be provided respectively.

The present invention is also an injection molding method using a hot runner type mold having the structure according to the present invention as described above, wherein (a) the gate is closed by the valve means and then the injection device is used. A step of filling the resin flow path with a molten resin material; and (b) a step of injecting the molten resin material into the molding cavity by releasing the closing of the gate by the valve means to open the gate.
(C) a step of dividing the resin flow path into the sprue side and the gate side by the flow path blocking means, and (d) pressurizing the molten resin material in the divided gate side resin flow path by the pressurizing means,
An injection molding method also includes a step of exerting a pressure on the resin material filled in the molding cavity, and a step of (e) closing the gate by the valve means and then opening the mold to take out the molded product from the molding cavity. , Is a feature.

Furthermore, when performing the injection molding according to the method of the present invention, after the resin flow path is divided by the flow path blocking means, in parallel with the molding process of the resin material filled in the molding cavity, the injection device It is also possible to perform a plasticizing step of the resin material for molding in the next cycle.

[0016]

EXAMPLES Examples of the present invention will now be described in detail with reference to the drawings in order to clarify the present invention more specifically.

First, FIG. 1 shows a schematic explanatory view of a hot runner type mold as one embodiment of the present invention. The mold of this embodiment is composed of a fixed mold 10 and a movable mold 12, and these molds 10 and 12 are matched with each other to form two molding cavities 16 on the mold matching surface 14. 16 are formed. The fixed mold 10 and the movable mold 12 are respectively attached to a fixed platen and a movable platen of a mold clamping device (not shown), and the movable mold 12 moves relatively to the fixed mold 10 in the approaching / separating direction. By being pressed, the mold closing, mold clamping and mold opening operations are performed. Also,
A resin flow path 18 is formed in the fixed mold 10 so as to extend from a portion where a nozzle of an injection device (not shown) abuts to the molding cavities 16 and 16. Through the resin flow path 18, a nozzle of the injection device is formed. The molten resin material injected from is guided to and filled in the molding cavities 16, 16. In this embodiment, the ejector mechanism for ejecting the molded product, which is provided on the movable mold 12 side and includes an ejector pin, is omitted in the drawings and the description.
As such an ejector mechanism, any conventionally known ejector mechanism can be appropriately adopted.

More specifically, the fixed mold 10 has a mounting block 20 mounted on a fixed plate of a mold clamping device (not shown).
And the molding cavity 1 is fitted to the movable mold 12.
The sprue block 24, the runner block 26, and the pair of cylinder blocks 28, 28 are assembled between the cavity forming block 22 and the cavity forming block 22 which form 6, 16 and are integrally connected by bolts or the like. ing.

The mounting block 20 has a thick, substantially flat plate shape, and a central hole 30 penetrating in the plate thickness direction is formed in the central portion thereof. And this mounting block 2
The cavity forming block 22 is arranged so as to be opposed to 0 at a predetermined distance. The cavity forming block 22 and the movable mold 12 that forms the forming cavities 16 and 16 in cooperation with the cavity forming block 22 have the forming cavities 16 and 1, respectively.
A cooling medium passage 31 through which water or the like is circulated is formed so as to be located around the molding cavities 6, 1.
The mold temperature around 6 can be controlled.

The sprue block 24 has a substantially thick cylindrical shape, is inserted and fixed in the central hole 30 of the mounting block 20, and is assembled by protruding a predetermined length toward the cavity forming block 22 side. ing. A spherical recess 32 is formed in the opening of the sprue block 24 on the side of the mounting block 20 and a nozzle of an injection device (not shown) touches the sprue block 24. A sprue is formed by a central hole extending from the bottom of the spherical recess 32 in the axial direction. 34 are configured.

Further, a runner block 26 is disposed on the protruding tip side of the sprue block 24, and is fixedly assembled between the sprue block 24 and the cavity forming block 22. This runner block 26
Has a substantially thick flat plate shape, and the sprue block 2
4 is arranged so as to spread in the direction perpendicular to the axis from the protruding tip portion of No. 4. Inside the runner block 26, two sprue-side runners 36, 36, which communicate with the sprue 34 of the sprue block 24 and extend at a predetermined length on both sides in the direction perpendicular to the sprue 34, are formed. . In addition, a mounting hole 38 that extends through the runner block 26 in the plate thickness direction (the direction in which the mounting block 20 and the cavity forming block 22 face each other) is provided at the tip of each sprue-side runner 36.

The sprue block 24 and the runner block 26 have a plurality of cartridge heaters 40 mounted around the sprue 34, the sprue-side runner 36 and the mounting hole 38. The runner 36 and the mounting hole 38 are heated. In addition, a heat insulating member 42 is interposed between the runner block 26 and the cavity forming block 22 to suppress heat transfer to the cavity forming block 22.

Further, two cylinder blocks 28, 28 are provided on both sides of the sprue block 24 in a direction perpendicular to the axis.
Is provided. The cylinder block 28 includes a main body 44 that is sandwiched between the mounting block 20 and the runner block 26 and assembled, and a projection 46 that projects from the main body 44 and is inserted and fixed in the mounting hole 38 of the runner block 28. It is configured.

The protrusion 46 of this cylinder block 28
Has a hollow cylindrical shape, and the sprue-side runner 36 formed in the runner block 26 communicates with and is connected to an axially intermediate portion of the inner hole thereof through a communication hole 48 formed through the peripheral wall portion. On the other hand, the gate 50 opening to the molding cavity 16 is formed by narrowing the tip side portion of the inner hole. That is, the resin material guided through the sprue-side runner 36 is passed through the gate 50 by the inner hole of the protruding portion 46, and the molding cavity 16
That is, the gate-side runner 52 for supplying to the. As is clear from the figure, the gate runner 52
Extend linearly from the gate 50 and extend beyond the connection portion of the communication hole 48 with the sprue-side runner 36 into the main body portion 44.

Further, inside the main body 44, a first cylinder chamber 56 having a first piston 54 is formed between the main body 44 and the mounting block 20.
By supplying and discharging hydraulic fluid through 60, the first piston 5
The driving force is applied to No. 4. In addition, inside the mounting block 20, at the assembly portion of each cylinder block 28, the second cylinder chamber 64 provided with the second piston 62 is axially arranged with respect to the first cylinder chamber 56 ( The second piston 62 is formed at a position separated by a predetermined distance in the piston movement direction), and the driving force is exerted on the second piston 62 by the supply and discharge of the hydraulic oil through the supply and discharge passages 66 and 68.

A first valve body 70 extending toward the protruding portion 46 is integrally formed with the first piston 54 disposed in the first cylinder chamber 56. The one valve body 70 is slidably fitted into the gate side runner 52, and is reciprocally driven in the axial direction by the driving force exerted by the first piston 54. The tip of the first valve body 70 is always fitted into the gate-side runner 52, and the first valve body 70 is
A sealing member is appropriately provided on the sliding surface between the gate-side runner 52 and the gate-side runner 52 to prevent the hydraulic oil in the first cylinder chamber 56 and the resin material in the gate-side runner 52 from leaking out. .

That is, when the first valve body 70 is pushed into the gate side runner 52 and the tip portion thereof exceeds the opening portion of the communication hole 48, the communication hole 48 is formed in the first valve body 7.
The sprue-side runner 36 and the gate-side runner 52 are covered with 0, so that the resin flow path 18 is blocked. Further, the first valve body 70 is pushed into the gate-side runner 52 beyond the opening of the communication hole 48, so that the pressure is exerted in the gate-side runner 52.

Further, the first valve body 70 and the first piston 54 are provided with an insertion hole 72 extending axially through their central portions. The second valve element 74 is inserted slidably in the axial direction. The second valve element 74 is in the shape of a long rod and has a tip portion 76 having an outer shape corresponding to the gate 50.
While protruding from the tip end portion of the first piston 54, the second piston 62 disposed in the second cylinder chamber 64 is fixedly provided at the base end portion thereof. The driving force exerted by the second piston 62 is adapted to be reciprocally driven in the axial direction. The second valve body 74 is projected into the gate-side runner 52 and the tip portion 76 is provided.
The gate 50 is closed by fitting it to the gate 50.

The second valve body 74 and the second valve body 7
4 through which the mounting block 10 and the first piston 54 are inserted.
A seal member is appropriately disposed between the first valve body 70 and the first valve body 70 to prevent leakage of hydraulic oil in the first and second cylinder chambers 56, 64 and resin material in the gate side runner 52. It is supposed to be done.

When molding the resin material using the hot runner type mold having the fixed mold 10 and the movable mold 12 having the above-mentioned structure, for example, the following method can be advantageously adopted. .

First, as shown in FIG. 1, the fixed die 10 and the movable die 12 are clamped, while the first piston 54 is retracted to connect the sprue runner 36 and the gate runner 52 to each other. At the same time, the second piston 62 is advanced to insert the tip end portion 76 of the second valve body 74 into the gate 50 to close the gate 50. And
By injecting an injection device (not shown) onto the sprue block 24 of the fixed mold and performing an injection operation, as shown in FIG. The side runner 36 and the gate side runner 52) are guided and filled. The sprue block 24 and the runner block 26 are heated by the cartridge heater 40 at the time of molding, and the cooling and solidification of the resin material 80 in the resin flow path is prevented.

That is, in this step, since the gate 50 is closed, the resin material 80 introduced into the resin flow path 18 of the fixed mold 10 is not yet injected into the molding cavity 16 but is injected. The resin is pressurized and held in the resin flow path 18 by the injection pressure of the device.

Next, as shown in FIG. 3, the second piston 62 is retracted while the first piston 54 is held in the retracted position, whereby the second valve element 74 is moved.
The front end portion 76 of the is removed from the gate 50 to open the gate 50.

That is, in this step, the gate 5
Simultaneously with the opening of 0, the resin material 80 pressurized and held in the resin flow path 18 is injected and filled in the molding cavity 16.

Immediately before or after the end of the filling of the resin material 80 into the molding cavity 16, as shown in FIG. 4, the second piston 62 is held in the retracted position and the first piston 62 is held. By moving the piston 54 forward,
The communication hole 48 is covered by the first valve body 70 to divide the sprue-side runner 36 and the gate-side runner 52, and the resin passage 1
8 is shut off and the first piston 54 is further advanced from there, so that the first valve body 70 exerts a pressure on the resin material 80 filled in the gate side runner 52.

That is, in this step, the first valve body 70 is moved forward, so that the resin material 80 filled in the gate side runner 52 passes through the resin material filled in the molding cavity 16, Further, a pressing force is exerted, and the resin material is compressed. Since the sprue-side runner 36 is not in communication with the molding cavity 16 when the resin material is compressed, it is not necessary to hold the pressure by the injection molding machine, and the next molding cycle is performed in parallel. It is also possible to enter the plasticizing step.

Even in the process of compressing and holding the resin material filled in the molding cavity 16 with the first valve body 70, the resin in the molding cavity 16 is cooled and solidified. However, during the resin cooling step, the second piston 62 is advanced while the first piston 54 is held at the advanced position, and the tip portion 76 of the second valve body 74 is inserted into the gate 50. By doing so, the gate 50 is closed.

As a result, the inside of the molding cavity 16 is blocked from the resin flow passage 18 under a pressure-holding state, and the resin material 80 in the resin flow passage 18 is heated by the cartridge heater 40 and melted. While being maintained in the state, the resin material in the molding cavity 16 is cooled and solidified by the refrigerant flowing through the refrigerant passage 31.

After the resin in the molding cavity 16 is cooled and solidified, the fixed mold 10 and the movable mold 12 are opened,
A target molded product is taken out by releasing the molded product from an ejector mechanism (not shown). When the mold is opened, the gate 50 moves the tip portion 7 of the second piston 62.
Since it is closed by 6, the leakage of the resin material 80 held in the molten state in the resin flow path 18 can be prevented.

Therefore, in the hot runner type mold having the above-described structure, the first piston 54 drives the first valve body 70 to drive the molding cavity 16
Gate runner 5 which is the resin flow path part directly connected to
Since the pressure is applied to the resin material 80 in the inside of 2, the pressure loss due to the resin flow path is minimized, and the large pressure is efficiently applied to the resin material filled in the molding cavity 16. As a result, even when molding small connectors or sockets having a large number of connection pin storage holes for a microcomputer board, the resin material can be advantageously and stably filled into the molding cavity 16. Molding defects due to short shots can be effectively reduced or prevented.

In addition, in such a hot runner type mold, a pressing force is applied to the resin material 80 kept in a molten state in the gate side runner 52 which is closed from the sprue side runner 36 and is hermetically sealed. Therefore, the resin material filled in the molding cavity 16 is advantageously pressurized, and the holding pressure for the resin material is advantageously maintained even when the resin material in the molding cavity 16 begins to cool and solidify. This makes it possible to back up against shrinkage, stabilizes the molding, and advantageously improves the dimensional accuracy of the molded product.

Further, if such a hot runner type mold is used, it is not necessary to set a large injection pressure in the injection molding machine, and thus a large injection molding machine is not required.

Further, in such a hot runner type mold, since the gate 50 is closed by the second valve body 74, resin leakage from the gate 50 at the time of mold opening, a phenomenon such as a sag phenomenon, etc. are effectively prevented. To get.

Further, in such a hot runner type mold, while the gate 50 is closed by the second valve body 74, the resin material 80 is filled into the resin flow path 18 from the injection device and pressurized. After that, by opening the gate 50 and injecting the pressure resin material 80 into the molding cavity 16,
The time for filling the resin material into the molding cavity 16 can be shortened, and in addition to that, when the resin material filled in the molding cavity 16 is held under pressure, the injection device is more effective than the sprue-side runner 36. Mold cavity 1 on the side
Since it is cut off from 6 and the pressure holding becomes unnecessary, in parallel with the step of cooling and solidifying the resin in the molding cavity 16,
It is also possible to carry out a plasticizing step for the next molding cycle, whereby a further improvement of the molding cycle can be achieved without using an injection device with a special function.

Further, in the hot runner type mold of this embodiment, since the hydraulic cylinder mechanism is adopted as the drive means of the first valve body 70, the operation for supplying / discharging to / from the first cylinder chamber 56. There is also an advantage that the pressure applied to the resin material in the molding cavity 16 can be easily adjusted and controlled by adjusting the oil pressure.

Further, in the hot runner type mold of this embodiment, since the hydraulic cylinder mechanism is adopted as the drive means of the first valve body 70, the diameter of the first piston 54 and the first valve 54 are Set the diameter ratio (area ratio) of the body 70 appropriately,
By changing the pressure, the pressure applied to the resin material in the molding cavity 16 can be easily adjusted, and a sufficiently large pressure can be applied by a simple structure.

Further, in the hot runner type mold of this embodiment, a flow path blocking means for connecting / blocking the sprue side runner 36 and the gate side runner 52 and a pressurizing resin material 80 in the gate side runner 52 are applied. Since the pressure means and the pressure means are both constituted by the first valve body 70, there is an advantage that the simplification of the structure and the facilitation of the operation control are advantageously achieved.

Further, in the hot runner type mold of this embodiment, the second valve body 7 is penetrated through the inside of the first valve body 70.
4 is provided, both valve bodies 70, 74 are provided.
Therefore, the installation space can be reduced, and the fixed mold 10 can be made compact.

Further, in the hot runner type mold of this embodiment, the cartridge heater 40 is provided not only around the runners 36 and 52 but also around the sprue 34, and the cartridge heater 40 is provided inside the resin flow path 18. Since the solidification of the resin material is prevented, continuous injection molding can be performed more stably, and the heat insulating member 42 is interposed between the runner block 26 and the cavity forming block 22. Heat transfer to 22 is suppressed,
Since the cavity forming block 22 is provided with the refrigerant passage 31 and can be cooled, there is also an advantage that the molding cycle can be improved by shortening the cooling process.

The embodiments of the present invention have been described in detail above, but these are literal examples, and the present invention should not be construed as being limited to such specific examples.

For example, in the above-mentioned embodiment, one specific example of applying the present invention to a mold having two molding cavities 16 and 16 is shown, but a mold having one or three or more molding cavities is shown. However, the present invention is similarly applicable.

The runner 3 branched from the sprue 34
The numbers of 6, 52 and gates 50 are determined according to the number of molding cavities and the number of sub-gates opened in the same molding cavity, and one or three or more can be provided.

Further, the flow path blocking means for dividing the resin flow path into the sprue side and the gate side, the pressurizing means for pressurizing the resin flow path on the gate side, and the valve means for opening / closing the gate are the same as those in the above-mentioned embodiment. The present invention is not limited to the above, and various conventionally known valve bodies, pressurizing mechanisms, and the like can be appropriately applied. For example, the flow path blocking means may be configured by a mechanism different from the pressurizing means, and a valve body inserted in a direction orthogonal to the resin flow path is used as the flow path blocking means or the valve means. It is also possible.

Also, when the first valve body 70 and the second valve body 74 as in the above-mentioned embodiment are adopted as the flow path blocking means, the pressurizing means, and the valve means, the first and second valve bodies 70 and 74 are adopted. As the driving means for the valve bodies 70 and 74, various well-known driving mechanisms such as solenoids and motors can be adopted in addition to the hydraulic cylinder mechanism as illustrated.

Further, the gate runner 52 may be directly formed in the runner block 26.

In addition, as the heating means for heating the runners 36 and 52, in addition to the cartridge heater as illustrated, various known electric power heaters such as strip type and band type can be adopted. According to the conventional method, temperature control using a thermocouple or the like is appropriately performed.

Although not listed one by one, the present invention
Based on the knowledge of those skilled in the art, it can be implemented in various modified, modified, and improved modes, and
It goes without saying that all such embodiments are included in the scope of the present invention without departing from the spirit of the present invention.

[0058]

As is clear from the above description, in the hot runner type mold having the structure according to the present invention, the pressing force is applied in the resin passage on the sprue side located near the molding cavity. Since the pressure loss due to the resin flow path is suppressed, a large pressing force is efficiently exerted on the resin material filled in the molding cavity, which advantageously and stably fills the resin material in the molding cavity. Thus, even when molding small articles, molding defects due to short shots or the like can be effectively reduced or prevented.

Moreover, in such a hot runner die, since the gate is closed by the second valve body, resin leakage and the like from the gate when the die is opened can be effectively prevented. It is possible to prevent a molding defect such as beating and to realize a more stable molding operation.

Further, when the hot runner type mold having the structure according to the present invention is used, it is not necessary to set a large injection pressure in the injection molding machine for pressurizing the resin material filled in the molding cavity. Therefore, a large injection molding machine is not required.

Further, in the hot runner type mold according to the present invention, the sprue-side runner is opened to communicate with the peripheral wall surface of the gate-side runner, and at the gate-side runner portion, there is a passage blocking means, It can be advantageously formed by disposing the pressure means and the valve means respectively.

Further, in such a hot runner type mold, the first valve body slidably fitted in the gate side runner constitutes the flow path blocking means and the pressurizing means, and the first valve body is provided. If the valve means is constituted by the second valve body that is slidably disposed so as to penetrate through the shaft in the axial direction, simplification and compactness of the structure can be advantageously achieved.

Furthermore, in the hot runner type mold having the structure according to the present invention, it is possible to branch from the sprue to provide a plurality of runners and gates, whereby a mold having a plurality of molding cavities and The present invention can be advantageously applied to a mold including a sub gate.

Further, by forming the refrigerant passage around the molding cavity, the influence of the heating means for heating the runner portion is reduced or eliminated, and the resin filled in the molding cavity is advantageously cooled and solidified. obtain.

If a heat insulating member is provided between the member forming the runner and the member forming the molding cavity, heat transfer from the runner side to the molding cavity side is suppressed, and the resin inside the molding cavity is prevented. The adverse effects of the heating means of heating the runner portion on the cooling and solidification process can be advantageously reduced.

Further, when the hot runner valve having the structure according to the present invention is adopted, a large pressing force is exerted on the resin material filled in the molding cavity so that the resin material is filled in the molding cavity with a large pressure. Therefore, it is possible to advantageously realize a hot runner type mold capable of effectively reducing or preventing molding defects due to short shots even when molding small articles.

Further, according to the method of the present invention, the pressure applied by the pressing means efficiently affects the resin material filled in the molding cavity regardless of the magnitude of the injection pressure exerted by the injection device. Therefore, molding defects due to short shots can be advantageously reduced or prevented without using a large injection device.

Furthermore, in the injection molding according to the method of the present invention, it is possible to carry out a plasticizing step for molding in the next cycle in parallel with the molding step using the resin material filled in the molding cavity. Therefore, the molding cycle can be advantageously improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view schematically showing the structure of a hot runner type mold as one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing only a hot runner valve portion for explaining one step of a molding operation using the hot runner type mold shown in FIG.

3 is a cross-sectional view of a hot runner valve portion for explaining a step following the step of FIG. 2 of a molding operation using the hot runner type mold shown in FIG.

FIG. 4 is a cross-sectional view of a hot runner valve portion for explaining a step following the step of FIG. 3 of a molding operation using the hot runner type mold shown in FIG.

5 is a cross-sectional view of a hot runner valve portion for explaining a step following the step of FIG. 4 of a molding operation using the hot runner type mold shown in FIG.

[Explanation of symbols]

 10 Fixed Mold 12 Movable Mold 16 Molding Cavity 18 Resin Flow Path 20 Mounting Block 22 Cavity Forming Block 24 Sprue Block 26 Runner Block 28 Cylinder Block 31 Refrigerant Passage 34 Sprue 36 Sprue Runner 40 Cartridge Heater 42 Thermal Insulation Member 44 Main Body 46 Projection portion 48 Communication hole 50 Gate 52 Gate side runner 54 First piston 56 First cylinder chamber 62 Second piston 64 Second cylinder chamber 70 First valve body 72 Insertion hole 74 Second valve body

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29C 45/73 7639-4F

Claims (10)

[Claims] 1. A hot runner type mold having a resin flow path consisting of a sprue, a runner and a gate for guiding a molten resin material supplied from an injection device to a molding cavity, and a heating means for heating such a runner portion. In, while providing a flow path blocking means for dividing the resin flow path into the sprue side and the gate side, pressurization for pressurizing the molten resin material in the gate side resin flow path divided by the flow path blocking means A hot runner mold is provided with valve means for opening and closing the gate while providing means. 2. The sprue-side runner connected to the sprue is opened to communicate with the peripheral wall surface of the gate-side runner connected to the gate, while the sprue-side runner provided on the peripheral wall surface of the gate-side runner is connected. The flow passage blocking means capable of covering the opening and separating the gate side runner and the sprue side runner, and the melting inside the gate side runner by being fitted into the gate side runner and pushed toward the gate side. The hot runner die according to claim 1, wherein the pressurizing means capable of pressurizing the resin material and the valve means capable of being inserted into the gate to close the gate are provided. 3. A first valve element slidably fitted into the gate-side runner constitutes the flow path blocking means and the pressurizing means, and penetrates the first valve element in the axial direction. The hot runner die according to claim 2, wherein the valve means is constituted by a second valve body slidably disposed. 4. The hot runner die according to claim 1, wherein a plurality of the runners and the gates are provided so as to branch from the sprue. 5. The hot runner type mold according to claim 1, wherein a coolant passage for temperature control is formed around the molding cavity. 6. The hot runner type gold according to claim 1, wherein the runner is formed of a member different from the molding cavity, and a heat insulating member is interposed between the two members. Type. 7. A linear runner portion having a gate formed at the tip opening portion, and a resin inlet opening formed in the peripheral wall surface of the runner portion, and sliding inside the runner portion in the axial direction. The first valve element which is arranged so that the resin inflow port can be communicated / blocked with the first valve element, and the runner portion can be pressurized by pushing the first valve element toward the gate side. On the other hand, a hot runner type in which a second valve body is slidably disposed so as to penetrate the first valve body in the axial direction, and the gate can be opened and closed by the second valve body Hot runner valve used for molds. 8. The first drive means for reciprocally driving the first valve element in the axial direction to connect / disconnect the resin inflow port and exert a pressing force on the runner portion, and the second drive means. 8. A second driving means for opening and closing the gate by reciprocally driving the valve body in the axial direction, respectively.
Hot runner valve described in. 9. A step of filling the molten resin material in the resin flow path by an injection device after closing the gate by the valve means, and releasing the closing of the gate by the valve means to open the gate. Thereby, a step of injecting and filling a molten resin material into the molding cavity, a step of dividing the resin flow passage into the sprue side and the gate side by the flow passage blocking means, and the division by the pressurizing means The step of pressurizing the molten resin material in the resin flow path on the gate side to exert a pressure on the resin material filled in the molding cavity, and closing the gate by the valve means, and then opening the mold. And a step of taking out a molded product from the molding cavity, the injection molding using the hot runner type mold according to claim 1. Law. 10. A resin for molding in the next cycle by an injection device in parallel with a molding step of the resin material filled in the molding cavity after the resin flow path is divided by the flow path blocking means. The injection molding method according to claim 9, wherein a plasticizing step of the material is performed.