JPH0367622A - Nozzle device for injection molding - Google Patents

Abstract

PURPOSE:To improve durability by simplifying the structure, by a method wherein a needle valve is provided movably longitudinally in a spatial part of the inside of a supporting member of the inside of a nozzle main body part and casting and choking of molten resin and pressurizing fluid are performed alternately at its tip part and rear end part. CONSTITUTION:When a screw 2 is moved forward, a needle valve 6 is moved forward with resin pressure, a communication port 54 is released and molten resin is injected into a mold from an injection port 56 by passing through a resin flow path 11 and resin inflow path 59. In this instance, a casting port 52a is closed with the tip part 61 of the needle valve 6 and prevents the molten resin from flowing backward into a spatial part 53 from the casting port 42a. Then when the screw 2 is moved backward, the needle valve 6 is moved backward with energizing force of a spring 63, a rear end part 62 abuts against and fitted into a communicating part 54 for blockade and communication of a resin inflow path 59 with a resin flow path 11 is covered. In this instance, the casting port 52a of the supporting member 52 is communicated with the spatial part 53, pressurizing fluid is fed into the spatial part 53 by passing through a feed passage 71 and communication passage 57 and cast into the mold from the lasting part 52a through the injection port 56.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an injection molding nozzle device that alternately injects molten resin and pressurized fluid into the cavity of a mold, and is used for molding hollow molded products. .

(Prior Art) Conventionally, as this type of injection molding nozzle device, one described in Japanese Patent Publication No. 59-49902 has been provided.

As shown in FIGS. 4 and 5, this injection molding nozzle device includes a first dollar valve disposed within the nozzle body via a support member al, which is formed at the tip of the nozzle body. The injection port C is closed, the molten resin is off-shafted, and the pressurized fluid is passed through the supply passage BL formed in the first needle valve from the tip opening d of the first needle valve as shown in the figure. First, the tip opening d of the one-dollar valve is closed by a thinner second needle valve e loosely fitted into the supply passage bl of the one-dollar valve. The valve is configured to shut off the pressurized fluid, and the maximum travel distance X of the first dollar valve is
, the moving distance Y of the first dollar valve when the injection port C opens, and the moving distance 2 of the second needle valve e until the tip opening d of the first dollar valve closes are such that x>y>z. In order to satisfy the conditions, the injection port C and the tip opening d were configured so as not to be open at the same time.

(Problems to be Solved by the Invention) However, the conventional injection molding nozzle device has a double structure in which the second needle valve e is disposed in the supply passage bl formed in the first needle valve. Therefore, there were problems in that the structure was complex and required high processing accuracy, increasing manufacturing costs, and it was weak in strength and poor in durability, so it could not be used for molding that required high molding pressure.

(Means for Solving the Problems) An injection molding nozzle device of the present invention is an injection molding nozzle device provided at the tip of an injection cylinder, and a support member is provided in a nozzle main body of the injection molding nozzle device. A needle valve is loosely fitted into the space formed in the support member so as to be movable back and forth, and the tip of the needle valve is placed facing the injection port formed at the tip of the support member. The rear end of the valve passes through the rear end of the support member and is disposed opposite to a communication port that communicates the resin inflow path formed by the support member and the nozzle body with the resin flow path of the injection cylinder; The space is provided with an urging means for urging the needle valve backward to close the communication port at the rear end of the needle valve, while the nozzle body is connected to a pressurized fluid supply source. A pressurized fluid supply pipe is connected, and a supply passage of the pressurized fluid supply pipe is communicated with the space, and when the needle valve moves forward and the rear end opens the communication port, the tip of the needle valve is configured to close the injection port.

(Function) First, when the screw is in the retracted position and no pressure is applied to the molten resin in the resin flow path in the injection cylinder, the rear end of the needle valve is brought into contact with the resin flow path due to the urging force of the urging means. It abuts and fits into a communication port that communicates with the resin inflow path in the nozzle main body, and closes this communication port. At this time, the tip of the needle valve retreats from the inlet provided at the tip of the support member to open this inlet, and the pressurized fluid supplied from the pressurized fluid supply source to the space is transferred to the inlet. From there, it can be injected into the mold cavity through the injection port at the tip of the nozzle. When the molten resin is injected, when pressure is applied to the molten resin in the resin flow path in the injection cylinder, the resin pressure moves the needle valve forward against the urging force of the urging means and opens the communication port. At the same time, the tip closes the injection port. As a result, the molten resin is injected from the injection port into the mold cavity via the communication port and the resin inflow path. During this injection, since the injection port is closed at the tip of the needle valve, the molten resin will not flow back into the space from the injection port of the needle valve.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show the structure of an injection molding nozzle device according to the present invention.

In the figure, reference numeral 1 denotes an injection cylinder having a screw 2 therein, and an injection molding nozzle device (hereinafter simply referred to as a nozzle device) 3 is provided at the tip of this injection cylinder 1.

The nozzle device 3 includes a nozzle body 5 connected to the tip of the injection cylinder 1, and a needle valve 6 disposed within the nozzle body 5 via a support member 52.

The nozzle body 5 is composed of a nozzle body 51 connected to the injection cylinder 1 and a nozzle tip 55 provided at the tip of the nozzle body 51. A space is formed that communicates with the resin flow path 11 of the injection cylinder 1, and a support member 52 that supports the needle valve 6 slidably in its axial direction is provided within this space. A gap existing between the support member 52 and the inner wall of the nozzle body 5 forms a resin inflow path 59.

The nozzle tip 55 is molded with an injection port 56 that communicates with the resin inflow channel 59, and when the tip of the injection port 56 is engaged with a mold (not shown), the sprue formed in the mold is connected. It is made to match.

A space 53 is provided within the support member 52, and the needle valve 6 is provided in this space 53 so as to be freely movable back and forth. The space 53 has an injection port 52 at its tip.
a is formed, and a through hole 52b is formed at the rear end.

The needle valve 6 has a distal end 61 facing the injection port 52a and disposed in the space 53, and a rear end 62 passing through the through hole 52b and disposed within the resin inflow path 59, When the needle valve 6 moves forward, its tip 61 closes the injection port 52a, and when the needle valve 6 moves backward, its rear end 62 closes the resin inflow path 59 and the resin flow path of the injection cylinder 1. 11 is configured to close the communication port 54. Further, a spring (biasing means) 63 is interposed in the space 53 so as to always bias the needle valve 6 rearward.

Here, since the resin pressure acting on the rear end 62 of the needle valve 6 is proportional to the axial area of the rear end 62, the pressure acting on the rear end 62 is equal to the pressure acting on the tip 61 and the spring 63. [Pressure acting on the rear end 62] Pressure acting on the tip 61 +
Biasing force of spring 63] The shaft diameter of the rear end portion 62 of the needle valve 6 must be set. In addition, the spring 63
The biasing force must be set to be sufficiently larger than the back pressure applied by the screw 2 during kneading.

Further, a pressurized fluid supply pipe 7 is communicated with the nozzle body 51, and a supply passage 71 of the pressurized fluid supply pipe 7 is connected to the space 53 via a communication passage 57 formed in the support member 52. It is communicated. The pressurized fluid supply pipe 7 is connected to a pressurized fluid supply source (not shown), and the pressurized fluid supplied from this pressurized fluid supply source is supplied to the supply passage 71 and the communication passage 57.
The liquid is supplied to the space 53 through the space 53, and is injected into the mold cavity from the injection port 52a of the space 53 through the injection port 56.

Next, the operation of the injection molding nozzle device configured as described above will be explained.

First, as shown in FIG. 2, when the screw is in the retracted position and no pressure is applied to the molten resin filled in the resin flow path 11 of the injection cylinder l, the needle valve 6 is moved by the biasing force of the spring 63. The rear end portion 62 abuts and fits into the communication port 54 to close the communication port 54, and the resin inflow path 59 and the resin flow path 11
It is blocking communication with. At this time, the injection port 52a communicates with the space 53 due to the retreat of the needle valve 6.

In this state, when the screw 2 is advanced toward the nozzle in order to inject the molten resin into the cavity, pressure is applied to the molten resin in the resin flow path 11, and this resin pressure causes the needle valve 6 to move as shown in FIG. As in, spring 6
3, the communication port 54 is opened and the resin inflow path 59 and the resin flow path 11 are communicated with each other. As a result,
The molten resin passes through the resin flow path 11 and the resin inflow path 59 and is injected from the injection port 56 into the mold cavity. At the time of this injection, the injection port 52a of the support member 5 is closed by the tip 61 of the needle valve 6 as the needle valve 6 moves forward.
It is possible to prevent the water from flowing back into the space 53.

Next, after a predetermined amount of molten resin is injected into the cavity, the screw 2 is retracted to open the resin inflow path 59 and the resin flow path 11.
When the resin pressure inside decreases, the needle valve 6 releases the spring 6.
The rear end 6 of the needle valve 6 moves backward again due to the urging force of 3.
2 is abutted and fitted with the communication port 54 to close the communication port 54 and block communication between the resin inflow path 59 and the resin flow path 11.

At this time, the injection port 52a of the support member 52 is opened and communicated with the space 53 as described above, and the pressurized fluid supplied from the pressurized fluid supply source is supplied to the supply passage 71, the communication passage 5
7 and into the space 53, and is injected from the injection port 52a of this space 53 through the injection port 56 into the cavity of the mold.

In this way, the bottom of the hollow molded product is shaped by alternately injecting the molten resin and the pressurized fluid into the cavity.

Further, the shape of both ends of the needle valve 6 is not limited to this example.
For example, as shown in FIG. 3, the leading end 61 may be formed in a stepped shape, and the rear end 62 may be formed in a tapered shape. At this time, the peripheral shape of the injection port 52a and the through hole 52b
Needless to say, the shape of the needle valve 6 is formed according to the shapes of both ends of the needle valve 6. Note that the other members are the same as those in the embodiment described above, and the same members are given the same reference numerals and explanations will be omitted.

(Effects of the Invention) As described above, according to the present invention, the structure is simple and the manufacturing cost is low, and it is also strong and durable, and can be used for bottom shapes that require high molding pressure. can be used.

[Brief explanation of drawings]

Figures 1 and 2 show the authority of the injection bottom type nozzle device according to the present invention. Figure 1 is a sectional view showing the state when the needle valve is advanced, and Figure 2 is a sectional view when the needle valve is retracted. 3 is a sectional view showing another embodiment of the needle valve, FIG. 4 is a sectional view showing a conventional injection bottom nozzle device, and FIG. 5 is a conventional injection bottom nozzle device. FIG. 3 is an enlarged view showing the tip portion of the nozzle device. 1... Injection cylinder 3... Injection bottom type nozzle device 5... Nozzle main body 6... Needle valve 7... Pressurized fluid supply pipe 11... Resin flow path 52... Support Member 52a... Inlet 53... Space 54... Stray port 59... Resin inflow channel 63... Spring (biasing means) 71... Supply channel Patent applicant Sekisui Chemical Kogyo Co., Ltd. Representative Hiroshi 1) Kaoru

Claims (1)

[Scope of Claims] 1) In an injection molding nozzle device provided at the tip of an injection cylinder, a support member is provided in a nozzle body of the injection molding nozzle device, and a space formed in the support member. A needle valve is loosely fitted in the part so as to be movable back and forth, and the tip of the needle valve is arranged facing the injection port formed at the tip of the support member, and the rear end of the needle valve is placed in front of the rear end of the support member. A needle valve is disposed opposite to a communication port that passes through the space and communicates the resin inflow path formed by the support member and the nozzle body with the resin flow path of the injection cylinder, and the needle valve is biased backward in the space. A biasing means for closing the communication port is provided at the rear end of the needle valve, and a pressurized fluid supply pipe connected to a pressurized fluid supply source is connected to the nozzle body. A supply passage of the pressurized fluid supply pipe is communicated with the space, and is configured such that when the needle valve moves forward and its rear end opens the communication port, the tip of the needle valve closes the injection port. An injection molding nozzle device characterized by: