JP2677433B2 - Injection molding nozzle device - Google Patents

Description

The present invention relates to a nozzle device for injection molding of thermoplastic synthetic resin.

(Prior Art) Conventionally, for example, as described in Japanese Patent Publication No. 59-49902 (see FIG. 6), an injection cylinder a and a die attached to the discharge part of the injection cylinder a In an injection molding apparatus having a nozzle device b that engages with a pouring port, the nozzle device b is concentrically provided with a needle c from a central axis, a valve having a fine hole and a sliding insertion hole communicating therewith at a tip end portion. A body d, an internal structure supporting material e, and a nozzle body f, and has a resin flow path composed of the valve body d and the nozzle body f, a fluid flow path composed of the valve body d and the needle c, and a needle Both c and the nozzle body f are fixed, the valve body d is movable in the axial direction of the nozzle device b by utilizing the resin pressure and the force of the compression spring g, and the valve body d moves forward to move the nozzle body f. Close the resin flow path by slidingly inserting it into the through hole at the tip of
When retracted, the tip of the needle c closes the sliding insertion hole at the tip of the valve body d to close the fluid flow path, and further retracts to open the resin flow path, thereby connecting the resin flow path and the fluid flow path. When opening and closing the two flow passages at the tip of the nozzle body f, the maximum movement distance of the valve body d is A, and the valve body d moves backward from the most advanced position to the tip of the nozzle body f. And B is the moving distance until the resin flow passage is opened, and C is the moving distance from the position where the valve body d is most advanced to the tip of the nozzle body f to the closing of the fluid flow passage, and these are A>B> C. There is known an injection molding nozzle device that satisfies the above conditions and prevents both flow paths from opening simultaneously in any state.

(Problems to be Solved by the Invention) However, in the above-described conventional technology, the structure is complicated, so that the processing is difficult, the manufacturing cost is high, the maintenance is troublesome, and the needle c is inserted into the hollow valve body d. , Weak strength, poor durability. Also, when a fluid such as a gas close to room temperature is injected, the valve body d is cooled, causing resin solidification at the boundary between the resin discharge port at the tip and the resin flow path or between the needle c and the valve body d. The resin flow path at the tip of the nozzle is blocked, and even if the discharge pressure of the molten resin is increased from the injection cylinder a, the molten resin does not flow and the nozzle device is easily damaged by the internal pressure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an injection molding nozzle device that solves the above-mentioned problems of the prior art, has a simple structure, is easy to maintain, and is highly durable.

(Means for Solving the Problem) The present invention provides an injection molding nozzle device mounted on a discharge part of an injection cylinder and engaged with an injection port of a mold,
A nozzle body and a first needle that is axially movable in the body using resin pressure and external force,
A resin flow path that is opened and closed by forward and backward movement of the first needle, a valve body, and a second needle that is axially movable in the valve body by utilizing pressurized fluid pressure and elastic force. And a fluid flow path that is opened and closed by the forward and backward movement of the second needle are arranged independently of each other, and the fluid flow is closed after the resin flow path is closed after the injection step of the molten resin into the mold cavity. A gist of an injection molding nozzle device is characterized in that a passage is opened to feed a pressurized fluid to a mold cavity.

The fluid channel of the present invention, as shown in FIGS.
The present invention is not limited to the one that is provided near the nozzle device 3 or the like so as to join the resin flow path 36, but as shown in FIG. Although it may be incorporated in the male die 51 of No. 5, in the latter case, there are few restrictions on the installation position, quantity, etc., compared to the former, and the degree of freedom in product design is high.

The movement of the needle of the present invention is not limited to that performed by injection pressure of resin or fluid and elasticity of the compression spring, and may be performed by providing an actuator such as a piston cylinder outside the nozzle body or the valve body. Good.

(Operation) The injection molding nozzle device of the present invention comprises a nozzle main body and a first needle that is movable in the axial direction in the main body by using resin pressure and external force, and the first needle is moved forward and backward. And a resin flow path that is opened and closed by a valve body, and a second needle that is movable in the valve body in the axial direction using pressurized fluid pressure and elastic force. Since the fluid channels that are opened and closed by moving forward and backward are provided independently of each other, the structure is simple, the durability is improved, and the maintenance is easy.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1 to 3 are longitudinal sectional views showing an embodiment of the injection molding nozzle device of the present invention and showing the operation of the device in the order of steps. FIG. 1 shows both the resin flow path and the fluid flow path. The closed state,
FIG. 2 shows the resin flow channel open and fluid flow channel closed states, and FIG. 3 shows the resin flow channel closed and fluid flow channel open states.

The injection cylinder 1 contains a screw 2 inside, and a nozzle device 3 is attached to the discharge end thereof. Inside the nozzle main body 31 consisting of the front part 311 and the rear part 312, there is a first needle 32 that is axially movable in the main body 31.
However, they are concentrically supported by the internal structure support body 33, and the nozzle body 31 and the first needle 32 form an annular resin flow path 36.

The first compression spring 34 mounted on the outer circumference of the nozzle body 31.
As shown in FIG. 4, the first needle 32 is constantly pressed to the mold side via the pressure transmission rod 35 penetrating the nozzle body 31 in the horizontal direction.

A second needle 41, which is movable in the valve body 4 in the axial direction, is provided in the vicinity of the rear end of the O-ring inside the valve body 4 provided near the upper front of the nozzle device 3. The diametrically expanded portion 42 to which 43 is fitted is supported concentrically, and the valve body 4
An annular fluid flow path 44 is configured by the second needle 41 and the second needle 41.

The second compression spring 45 is attached to the rear of the expanded diameter portion 42 of the valve body 4 and always presses the second needle 41 forward.

46 is connected to a pressurized fluid source (not shown) to
44 is a pressurized fluid inlet adapted to merge with 44.

Next, the operation process of the molding apparatus of the present invention will be described based on the above-mentioned embodiment.

At the stage of starting molding, as shown in FIG.
The needle 32 is pressed by the first compression spring 34 toward the mold side to close the tip of the resin flow path 36, and the second needle 41
Is pressed by the second compression spring 45 to close the tip of the fluid flow path 44.

Next, in order to inject the resin into the mold, an injection pressure is applied to the resin plasticized by the screw 2, and as shown in FIG. 2, this pressure causes the first needle 32 to move to the first
Is retracted against the compression spring 34, the tip of the resin flow path 36 is opened, and the plasticized resin is injected into the mold cavity of the mold.

When a predetermined amount of resin is injected into the fossae, the screw 2
The pressure due to is removed, the first needle 32 is pressed toward the mold by the first compression spring 34, and returns to the state of FIG.
The tip of the resin flow path 36 is closed.

After the injection process is completed, the injection of the pressurized fluid is started from the pressurized fluid inlet 46, and the expanded diameter portion 42 of the second needle 41 is pressed backward, and the second needle 41 is moved to the second compression spring 45. As shown in FIG. 3, the tip of the fluid flow path 44 is opened, and the pressurized fluid is fed into the resin in the mold cavity.

When the feeding of the pressurized fluid is completed, the second needle 41
It is pressed by the second compression spring 45 to return to the state shown in FIG. 1 and closes the tip of the fluid passage 44.

(Effect of the invention) Since the injection molding nozzle device of the present invention is configured as described above, the structure is simple and can be manufactured at low cost, and the maintenance cost can be reduced and the durability can be improved. Molding is not interrupted due to resin freezing.

[Brief description of the drawings]

1 to 3 are vertical sectional front views showing respective steps of one embodiment of the present invention, FIG. 4 is a vertical sectional side view of FIG. 1, and FIG. 5 is a vertical sectional view showing the other embodiment. FIG. 6 is a vertical sectional view showing a conventional example. 1 ... Injection cylinder, 3 ... Nozzle device, 4 ... Valve body, 31 ... Nozzle body, 32 ... First needle, 36 ... Resin flow path, 41 ... Second needle, 44 ... Fluid flow path.

Claims (1)

(57) [Claims] 1. A nozzle device for injection molding, which is mounted on a discharge part of an injection cylinder and is engaged with an injection port of a mold, comprising:
A nozzle body and a first needle that is axially movable in the body using resin pressure and external force,
A resin flow path that is opened and closed by forward and backward movement of the first needle, a valve body, and a second needle that is axially movable in the valve body by utilizing pressurized fluid pressure and elastic force. And a fluid flow path that is opened and closed by the forward and backward movement of the second needle are arranged independently of each other, and the fluid flow is closed after the resin flow path is closed after the injection step of the molten resin into the mold cavity. A nozzle device for injection molding, characterized in that a passage is opened to feed a pressurized fluid into a mold cavity.