JP6422548B1 - Hot runner unit - Google Patents

Abstract

To provide a hot runner unit capable of discharging gas generated from a molten resin with high efficiency.
A hot runner unit is disposed between a gate of an injection mold and a nozzle for discharging molten resin. The hot runner unit includes a nozzle connection portion to which the nozzle is connected, and includes a sprue portion having therein a molten resin flow path for guiding the molten resin discharged from the nozzle to the gate. And the one part area of the said molten resin flow path of the said sprue part was comprised by the vent member which has a some fine hole of the magnitude | size which the tube wall does not allow the said molten resin to pass through, but allows only gas to pass through It is a vent section.
[Selection] Figure 1

Description

  The present invention relates to a hot runner unit that is disposed between a gate of an injection mold and a nozzle that discharges molten resin, and guides the molten resin discharged from the nozzle to the gate while heating.

  As a resin product manufacturing technique, injection molding using a hot runner system is known. The hot runner system is configured to heat the runner for guiding the molten resin to the gate of the mold. In the hot runner system, the molten resin is heated in the runner and maintained at a high temperature state with high fluidity.

  In injection molding, gas is generated when the resin is plasticized. If this gas remains in the cavity of the mold, it may cause an appearance defect or a filling defect of the molded product. Therefore, measures such as providing a mechanism for discharging the gas generated from the molten resin to the outside of the mold are generally taken (see Patent Document 1). In addition, in the cold runner system which does not heat a runner, providing the gas venting structure on a runner is also proposed (refer patent document 2).

Japanese Patent Laying-Open No. 2015-164766 JP 2012-101524 A

  It is inefficient to exhaust the gas that has entered the mold as in the prior art, and if the mold product is finely nested, the number of processing steps increases and the cost increases. However, in the hot runner system, it is not easy to provide a gas vent structure on the runner as in Patent Document 1. Since the fluidity and pressure of the molten resin are higher in the hot runner than in the cold runner, if the gas venting mechanism similar to the cold runner is provided in the hot runner, the molten resin leaks from the vent hole.

  In addition, it is difficult to form a fine hole by drilling so that the molten resin in a high temperature and high pressure state does not leak and only the gas is discharged to the outside. For this reason, the same concept as the cold runner system is adopted, and the gas venting structure disclosed in Patent Document 1 cannot be applied to the hot runner system as it is.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a hot runner unit capable of discharging gas generated from a molten resin with high efficiency.

  The present invention is a hot runner unit disposed between a gate of an injection mold and a nozzle for discharging a molten resin, and has a nozzle connecting portion to which the nozzle is connected, and is discharged from the nozzle. A sprue portion having a molten resin flow path for guiding the molten resin to the gate is provided. And the one part area of the said molten resin flow path of the said sprue part was comprised by the vent member which has a some fine hole of the magnitude | size which the tube wall does not allow the said molten resin to pass through, but allows only gas to pass through It is a vent section.

  In the hot runner unit of the present invention, it is preferable that a small-diameter section having an inner diameter smaller than that of the vent section is provided on the gate side of the molten resin flow path. If it does so, the pressure in a vent area will rise and the discharge efficiency of the gas in a vent area will improve.

  Examples of the vent member include a plurality of ring-shaped members that are arranged on the same axis and stacked with close contact surfaces. In this case, a groove forming the fine hole is formed in the close contact surface of the ring-shaped member. With the vent member having such a structure, it is possible to provide fine holes that allow only the gas to pass without passing the molten resin in a high-temperature and high-pressure state.

  In the hot runner unit according to the present invention, a vent member having a plurality of fine holes of a size that allows only a gas to pass through a partial section of the molten resin flow path of the sprue portion without passing the molten resin. Therefore, the gas generated from the molten resin can be discharged to the outside before entering the mold. This eliminates the need to provide a gas vent structure in the product part of the mold.

It is a schematic sectional block diagram which shows one Example of a hot runner unit. It is sectional drawing which shows the specific structure of the sprue part of the Example.

  Hereinafter, one example of a hot runner unit according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the hot runner unit 2 is arranged between a nozzle 12 for discharging a molten resin and a gate of an injection mold to construct a hot runner system. . The hot runner unit 2 includes a hot runner block 4 and a sprue portion 6.

  The sprue portion 6 is provided with a nozzle connecting portion 10 for contacting and connecting a nozzle 12 for discharging a molten resin to one end side, and a molten resin for guiding the molten resin discharged from the nozzle 12 to the gate side. A flow path 14 is provided inside. The sprue portion 6 is fixed by being fitted into a recess 5 provided in the hot runner block 4.

  In the hot runner block 4, a flow path 8 is provided for guiding the molten resin that has passed through the molten resin flow path 14 of the sprue portion 6 to the gate of the mold. In this embodiment, the flow path 8 provided in the hot runner block 4 is branched so as to lead to two gates, but the number of branches of the flow path 8 is not limited to this, and one place It may not be branched so as to guide the molten resin only to the gates, or may be branched so as to guide the molten resin to three or more gates.

  A part of the section between the one end portion and the other end portion of the sprue portion 6 has a minute hole having a size that allows only the gas generated from the molten resin to pass without passing the molten resin flowing through the molten resin flow path 14. A vent section in which a tube wall is formed by the vent member 16 is formed. The gas generated from the molten resin is discharged to the outside of the molten resin flow path 14 through the fine holes of the vent member 16 constituting the pipe wall of the vent section 16.

  The hot runner block 4 is provided with an intake passage 18 for taking outside air into the hot runner block 4 and an exhaust passage 20 for discharging the air in the hot runner block 4 to the outside. A suction pump 24 is connected to the exhaust flow path 20 via a pipe, and the gas in the hot runner block 4 can be sucked by the suction pump 24 and discharged, for example, outdoors. A filter 22 for precipitating and removing harmful substances is provided on the upstream side of the suction pump 24.

  Although not shown, a heater is embedded in the hot runner block 4 so that the molten resin flowing in the molten resin flow path 14 and the flow path 8 in the sprue portion 6 is heated. . In order to transfer the heat from the heater to the molten resin, both the hot runner block 4 and the sprue portion 6 are made of a metal having good thermal conductivity.

  An example of the structure of the sprue portion 6 is shown in FIG.

  The sprue portion 6 includes a touch sprue 26, a vent sprue 28, and a connect sprue 30. The vent sprue 28 is a hollow cylindrical member having a through hole 36 on the inner side, and cylindrical recesses 32 and 34 having an inner diameter larger than that of the through hole 36 are provided on one end side and the other end side, respectively.

  The touch sprue 26 has a nozzle connecting portion 10 for contacting the nozzle 12 (see FIG. 1) on one end side (right side in the drawing), and a protrusion 26a on the other end side (left side in the drawing). The connection sprue 30 has a protrusion 30a on one end side (right side in the drawing) and a screw 44 that is screwed with a screw provided on the inner surface of the recess 5 of the hot runner block 4 on the outer peripheral surface on the other end side.

  The inner diameter of the recess 32 of the vent sprue 28 is substantially the same as the outer diameter of the protrusion 34 of the touch sprue 26, and a screw that is screwed to the inner surface of the recess 32 of the vent sprue 28 and the outer surface of the protrusion 26 a of the touch sprue 26 is provided. ing. Further, the inner diameter of the recess 34 of the vent sprue 28 is substantially the same as the outer diameter of the protrusion 30a of the connect sprue 30, and a screw that is screwed together with the inner surface of the recess 34 of the vent spru 28 28 and the outer surface of the protrusion 30a of the connect sprue 30. Is provided.

  A plurality of according rings 38 (ring-shaped members) having a hollow disk shape are accommodated in the through hole 36 inside the vent sprue 28 in a stacked state. The outer diameter of the according ring 38 is designed to be slightly smaller than the outer diameter of the through hole 36, and there is a slight gap between the inner surface of the through hole 36 and the according ring 38.

  The plurality of coating rings 38 disposed in the through holes 36 of the vent sprue 28 in a stacked state are sandwiched between the front end surface of the protrusion 26a of the touch sprue 26 and the front end surface of the protrusion 34a of the connect sprue 34. 26 and the connection sprue 34 are pressed from both sides by tightening screws to the vent sprue 28.

  A fine groove is formed on the laminated surface of the according ring 38, and the groove does not allow the molten resin flowing through the molten resin flow path 14 to pass therethrough, and has a fine hole of a size that allows only gas generated from the molten resin to pass therethrough. Configure. That is, the plurality of coating rings 38 disposed in the through holes 36 of the vent sprue 28 in a stacked state realize the vent member 16 that forms a tube wall having fine holes that allow only gas to pass without passing molten resin. It is.

  The vent sprue 28 is provided with two openings 40 and 42 leading to the through hole 36. The opening 40 is in fluid communication with the intake flow path 18 (see FIG. 1), and the opening 42 is in fluid communication with the exhaust flow path 20 (see FIG. 1). The outside air taken into the through hole 36 through the opening 40 passes through the gap between the through hole 36 and the according ring 38 and is discharged from the opening 42 to the outside of the vent sprue 28. As a result, the gas in the molten resin flow path 14 that has passed through the fine holes provided in the vent member 16 is forcibly discharged to the outside of the sprue portion 6 through the opening 42.

  In this embodiment, a small diameter having an inner diameter smaller than the inner diameter of the vent section on the downstream side (left side in FIG. 2) of the vent section realized by the vent member 16 in the molten resin flow path 14 inside the sprue portion 6. A portion 14a is provided. As a result, the pressure in the molten resin flow path 14 on the upstream side of the small diameter portion 14a is increased, and the gas in the molten resin flow path 14 is easily discharged to the outside of the molten resin flow path 14 through the fine holes of the vent member 16. Become.

  As described above, the hot runner unit 2 of this embodiment can remove the gas generated from the molten resin before the molten resin discharged from the nozzle 12 reaches the gate of the mold. Since it is comprised in this way, it can suppress that gas infiltrates into a metal mold | die. This eliminates the need for degassing the mold and can reduce costs.

2 hot runner unit 4 hot runner block 6 sprue part 8 flow path 10 nozzle connection part 12 nozzle 14 molten resin flow path 14a small diameter part 16 vent part 18 intake flow path 20 exhaust flow path 22 filter 24 suction pump 26 touch sprue 28 vent sprue 30 Connect sprue 32, 34 Recess 36 Through hole 38 Acoding ring (ring-shaped member)
40, 42 opening

Claims (2)

A hot runner unit disposed between a gate of an injection mold and a nozzle for discharging a molten resin,
A nozzle connecting portion to which the nozzle is connected, and a sprue portion having a molten resin flow path for guiding the molten resin discharged from the nozzle to the gate,
A partial section of the molten resin flow path of the sprue portion is a vent section formed by a vent member having a plurality of fine holes whose tube wall allows only gas to pass without passing through the molten resin. It has become,
A hot runner unit in which a small-diameter section having an inner diameter smaller than that of the vent section is provided on the gate side of the molten resin flow path . A hot runner unit disposed between a gate of an injection mold and a nozzle for discharging a molten resin,
A nozzle connecting portion to which the nozzle is connected, and a sprue portion having a molten resin flow path for guiding the molten resin discharged from the nozzle to the gate,
A partial section of the molten resin flow path of the sprue portion is a vent section formed by a vent member having a plurality of fine holes whose tube wall allows only gas to pass without passing through the molten resin. And
The vent member comprises a plurality of ring-shaped member that is laminated with a contacting face each other in a state of being disposed coaxially, the grooves forming the fine hole in the contact surface of the ring-shaped member is formed, Ho Tsu A runner unit.

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