JPH07223241A - Shut-off nozzle for injection molding machine - Google Patents

Abstract

PURPOSE:To manufacture inexpensively a shut-off nozzle of simple structure for an injection molding machine which can use the molding temperature of wide range and open and close securely a gate and a slide nozzle without applying excessive force to a needle pin. CONSTITUTION:A shut-off nozzle for an injection molding machine is provided with a nozzle gate 31 for bringing the nozzle into contact with a sprue 30 of a mold to form a resin reservoir section 30 and a slide nozzle 32 fitted slidably into the nozzle gate 31 and provided with a resin flow outlet 32a on its central section. Further, a needle pin 35 and a valve retained slidably by the given distance in the axial direction and closing a gate 30b formed on a sprue 30 to be set on the front end and a valve for closing the resin flow outlet 32a of the slide nozzle 32 to be set on the rear end and a fluid cylinder 34 for moving the slide nozzle 32 back and forth through an arm 32 are provided on the slide nozzle 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shut-off nozzle for a mold with a hot runner (pre-chamber type mold) in an injection molding machine.

[0002]

2. Description of the Related Art Conventionally, as a shut-off nozzle (gate opening / closing device) of a pre-chamber type mold in an injection molding machine, for example, the one shown in Japanese Utility Model Publication No. 4-18833 has been proposed. This will be described with reference to FIG. 8. 1 is mounted on the fixed platen 2, and the mold 1 is mounted with a sprue bush 3. Reference numeral 4 denotes a plasticizing cylinder, a nozzle 5 is attached to the tip of the plasticizing cylinder, and a screw 6 is arranged inside. A torpedo 7 is provided on the side of the nozzle 5 of the plasticizing cylinder 4, and a lever 8 having one end movably inserted in the rear portion of the torpedo 7 is pivotally mounted on the side of the torpedo 7. A needle valve 9 is slidably mounted in the torpedo 7, and the needle valve 9
The rear end is pivotally attached to one end of the lever 8. Reference numeral 10 denotes a needle pin which is concentrically and integrally connected to the tip of the needle valve 9 and penetrates through the resin outlet of the nozzle 5 and the sprue bush 3. The sprue bush 3
A pinpoint gate 11 is provided at the front end of the sprue bushing 3, and a space for the pool is provided inside the rear end of the sprue bush 3 so that the space is closed to form the pool 12. The tip of the nozzle 5 is held in contact with the nozzle during continuous molding.

Reference numeral 13 is a needle opening / closing cylinder. The other end of the lever 8 is pivotally attached to the rod tip of the cylinder 13, and a hydraulic pump 16 is connected to the rod side chamber via a pressure reducing valve 14 and a switching valve 15. When the energizing coil 15a of the switching valve 15 is not energized, the hydraulic pump 16 moves the pressure reducing valve 1
The hydraulic pressure set in 4 is supplied to the rod side chamber to perform the rod retraction operation, and the exciting coil 15a of the switching valve 15 is energized to be excited. When the switching valve 15 is switched, the rod side chamber and the tank 17 communicate with each other. The rod is adapted to move forward. Since the needle valve 9 and the needle pin 10 are configured as described above, the needle opening / closing cylinder 13
When the rod retracting operation is performed, it advances through the lever mechanism 8 to the resin outlets at the tip of the nozzle 5 and the gate 11 at the tip of the sprue bush 3, and closes them simultaneously. , The needle valve 9 by the resin pressure acting on the tip surface of the needle valve 9
Automatically retracts to simultaneously open the resin outlet at the tip of the nozzle 5 and the tip gate 11 of the sprue bush 3. The movable mold 18 is mounted on the movable platen 19, and is retracted with respect to the fixed mold 1 by a mold clamping device (not shown) to perform mold opening / closing and mold clamping. The cavity 20 formed in the molds 1 and 18 that have been clamped is injected and filled with the molten resin from the plasticizing cylinder 4 side through the nozzle 5, the resin reservoir 12, and the gate 11.

The operation of the conventional example constructed as described above will be explained. During injection molding, the rod side chamber of the needle opening / closing cylinder 13 is made to communicate with the tank 17, and then the injection pressure is applied by the screw 6 in the plasticizing cylinder 4. Then, the needle valve 9 and the needle pin 10 are automatically retracted by the resin pressure to open the resin outlet at the tip of the nozzle 5 and the gate 11 at the tip of the sprue bush 3, so that the molten resin is injected and filled in the cavity 20. It Then, holding pressure and cooling are performed to complete the molded product. Next, when hydraulic pressure is supplied to the rod side chamber of the needle opening / closing cylinder 13 to perform the rod retraction operation, the needle valve 9 and the needle piston 10 are advanced through the lever mechanism 8 and the resin outlet at the tip of the nozzle 5 is formed. The gate 11 at the tip of the sprue bush 3 is closed, and the mold can be opened in this state to eject the molded product by the ejector mechanism. At the same time, the mold is closed and the mold is clamped to shift to the injection molding of the next cycle. When it is necessary to change the molding temperature over a wide range depending on the molded product, the pressure reducing valve 14 changes the set pressure to a smaller value when the temperature is higher and to a larger value when the temperature is lower according to the change in the molding temperature. Needle pin 1 by setting the closing force (cylinder pressure)
0 and sprue bushing 3 should not wear.

[0005]

However, in the conventional gate opening / closing device for the pre-chamber type mold,
When adjusting the force to close the gate according to the molding temperature as described above, it is necessary to change the mold and molding temperature in actual work, and depending on the conditions, the amount of expansion and contraction due to heat of the mold and needle pin. However, there were the following problems. (1) When the expansion amount on the die side is larger than the expansion amount on the needle pin side, the resin outlet of the nozzle is closed but the gate of the sprue bush is not closed, and resin stringing occurs. (2) When the expansion amount on the die side is smaller than the expansion amount on the needle pin side, the resin outlet of the nozzle does not close even if the gate of the sprue bush closes, and the force applied from the needle opening / closing cylinder is It gets on the tip and bends the needle pin or wears the tip. (3) Since the tip end surface of the nozzle forms a right angle with the side wall of the resin reservoir, the resin retained in this corner does not easily flow, and old resin is likely to remain when the resin is changed (color changed). (4) The dimension from the opening / closing part of the sprue bush of the needle pin to the resin outlet of the nozzle and the dimension from the gate of the mold to the resin outlet of the nozzle must accurately match, which makes manufacturing difficult. , Costly. The present invention can solve various problems in the conventional device and can cope with a wide range of molding temperatures, and can easily open and close the gate and the nozzle without applying an excessive force to the needle pin. The present invention aims to provide a shut-off nozzle for a new injection molding machine.

[0006]

Therefore, according to the present invention, in a shut-off nozzle of an injection molding machine, a nozzle guide that abuts against a sprue of a mold so as to mold a resin pool portion, and a slide on the nozzle guide. A slide nozzle that is freely fitted inside and has a resin outlet in the center, and a valve that is slidably held by the slide nozzle within a certain distance in the axial direction and that closes the gate provided on the sprue at the tip. A needle pin having a valve for closing a resin outlet of the slide nozzle at a rear end thereof, and a fluid cylinder for moving the slide nozzle forward and backward through an arm, which is a means for solving the problem. is there. Further, the present invention, a nozzle guide that abuts against a sprue of a mold so as to form a resin reservoir portion, and a slide nozzle that is slidably fitted in the nozzle guide and has a resin outlet in the central portion. The slide nozzle is slidably held within a certain distance in the axial direction, and a needle pin having a valve for closing a gate provided on the sprue at a front end and a valve for closing a resin outlet of the slide nozzle at a rear end, And a fluid cylinder for moving the slide nozzle forward and backward, the fluid cylinder comprising a part of the nozzle guide as an outer cylinder and a part of the slide nozzle as a piston. To do. Furthermore, the present invention provides a nozzle guide that abuts against a sprue of a mold so as to form a resin reservoir, and a valve that is slidably fitted in the nozzle guide and that closes a gate provided on the sprue at the tip. , A needle cylinder having a plurality of grooves serving as a resin outlet passage in an intermediate portion and a fluid cylinder for moving the needle pins forward and backward through an arm, and when the needle pins advance, the plurality of grooves form a nozzle. The nozzle is configured to be closed by the wall surface of the hole, and the shape of the tip end surface of the nozzle facing the pool portion is sequentially projected in an arc shape as it goes away from the inner peripheral portion in the outer peripheral direction. It is formed, and is used as a means for solving the problem.

[0007]

According to the present invention, when the nozzle guide is inserted into the rear portion of the sprue and brought into contact with the sprue by the above means, and the slide nozzle is moved forward through the arm by the fluid cylinder, the needle pin becomes the sprue and the slide nozzle. Stopping in the sandwiched state, the valve element at the tip of the needle pin closes the gate of the sprue, and the valve element at the rear end closes the resin outlet of the slide nozzle. Since the pressure applied to the front and rear of the slide nozzle is balanced by the areas of both end faces, a small force is required to push the slide nozzle. Next, when the slide nozzle is retracted, the resin outlet is opened first, and then the slide nozzle pulls the needle pin to open the gate. After injecting the resin into the mold, the slide nozzle is moved forward to bring about the above state. After cooling, the mold is opened and the product is taken out. Further, when the fluid cylinder is formed by the nozzle guide and the slide nozzle, the point that the slide nozzle is directly driven to move forward and backward is changed, but other actions are the same as the above. Further, when a needle pin having a groove serving as a resin outlet passage is provided in the middle part, when the needle pin is advanced through the arm in the fluid cylinder, the valve body at the tip of the needle pin moves the sprue gate to the nozzle. The through hole closes the groove entrance of the needle pin. When the needle pin is retracted, the gate of the sprue is opened first, and then the groove of the needle pin comes out of the through hole of the nozzle to open the resin outlet. The procedure of injection molding is the same as above. Further, since the corner portion formed by the nozzle tip surface and the sprue wall surface is eliminated, the flow of the resin is improved, and it is possible to prevent the old resin from remaining when changing the resin.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments of the drawings. FIGS. 1 to 7 show the embodiments of the present invention. Since the structure of the injection molding machine to which the shut-off nozzle is applied is almost the same as that of the conventional example, detailed description thereof will be omitted. 1 and 2 are cross-sectional views showing a main part of a first embodiment of a shut-off nozzle according to the present invention. Reference numeral 30 denotes a sprue mounted on a stationary mold (the boundary between the stationary mold and the sprue is not shown). 30a is a resin reservoir (space) formed inside the sprue 30, 30b is a gate provided at the tip of the sprue 30, 31 is a nozzle guide inserted into the rear of the sprue 30, and 31a is an arm described later. An elongated hole provided in the nozzle guide 31 for passing 33, a slide nozzle 32 slidably fitted in an inner peripheral portion of the nozzle guide 31,
Is an arm fixed to the slide nozzle 32, 34 is a double-acting fluid cylinder for moving the slide nozzle 32 forward and backward through the arm 33 in the direction of arrow B, and 35 is arranged in the resin reservoir 30a and the gate 30b is provided. And a needle pin located between the slide nozzle 32. During continuous molding, the nozzle guide 31 has its tip cylindrical portion inserted into the inner peripheral portion of the sprue 30, and the conical portion is brought into contact with the conical portion at the rear end of the sprue 30 (FIGS. 1 and 2 show this state. ), The inner peripheral portion of the slide nozzle 32 has a large diameter portion and a resin outlet 32a.
And a large diameter part, and the large diameter part is shown in FIG.
As shown in the sectional view A), a plurality of springs 32b are formed in the radial direction.
Needle pin 3
5 is concentrically and slidably held, and the front end of the needle pin 35 forms a conical valve body, and the gate 30
b, the gate 30b is closed and the rear end has a flange portion 35a, and the outer end surface of the flange portion 35a is a flat seat valve body (or a conical valve body). The resin outlet 32a is brought into contact with the end face (step) of the resin outlet 32a to close the resin outlet (FIG. 1 shows a closed state of the gate and the resin outlet, and FIG. 2 shows an opened state). . The conical portion provided at the center of the rear end surface of the flange portion 35a can smoothly guide the resin flow.

FIG. 4 is a sectional view showing an essential part of the second embodiment.
The same or similar members as in the first embodiment are designated by the same reference numerals. In this embodiment, a cylinder chamber 31b is formed in the nozzle guide 31 itself without providing a separate fluid cylinder as in the first embodiment, and two fluid inlets / outlets 31c communicating with the cylinder chamber 31b are provided. A part of the intermediate portion on the outer peripheral side of the slide nozzle 32 housed in the nozzle guide 31 has a large diameter and is projected in a flange shape to form a piston portion 32c. This is a substitute for the cylinder 34 in the embodiment. In addition,
Illustration of packings and the like for keeping the working fluid airtight is omitted.

FIGS. 5 and 6 are cross-sectional views of the essential part showing the third embodiment (FIG. 5 shows the state in which the gate and the resin outlet are closed, and FIG. 6 shows the state in which they are open). Nozzle, 42
Is a torpedo (the boundary between the nozzle and the torpedo is not shown), 43 is a needle pin, 44 is an arm fixed to the needle pin 43, and 45 is a fluid for moving the needle pin 43 forward and backward via the arm 44. It is a cylinder. The needle pin 43 includes a nozzle 41 and a torpedo 42.
Is slidably fitted in a hole that concentrically passes through the shaft center of the gate of the gate 30b.
, The gate is closed and the rear end projects to the outside of the torpedo 42, and an arm 44 is rigidly fixed to the projection at a right angle. Further, as shown in FIG. 7 (D-D cross-sectional view of FIG. 5), one or a plurality of grooves 43a (three in FIG. (Shown), the groove 43a is provided in the nozzle 41
When the needle pin 43 is longer than the through hole in the axial direction and the needle pin 43 is in the retracted position (FIG. 6), both ends of the groove may come out of the through hole of the nozzle, and the molten resin may flow in the direction of arrow G. Yes, the inlet of the groove is closed when the needle pin 43 is in the advanced position (FIG. 5).

Next, referring to FIGS. 5 and 6, a fourth embodiment will be described. The shape of the tip end surface of the nozzle 41 inserted into the resin reservoir portion 30a of the sprue 30 shown in the third embodiment will be described. As shown in FIG. 5, the end surface E (2
Instead of the one indicated by the dashed line, the end face F (solid line) is formed so as to sequentially project in an arcuate line as it goes away from the inner peripheral portion in the outer peripheral direction.

Next, the operation of each embodiment of the shut-off nozzle described above will be described. In the case of the first embodiment In FIG. 1, the slide nozzle 32 is pushed by the liquid cylinder 34 via the arm 33 and is in the forward position (leftward position), and the end face of the resin outlet 32a is located at the flange portion 32a of the needle pin 32. The needle pin 35 is pushed by the slide nozzle 32 to move forward (to the left),
The conical valve body portion at the tip is brought into contact with the gate 30b to close it. At this time, the arm 33 is provided with the long hole 3 of the nozzle guide 31.
Since it is configured so as not to contact the end surface of 1a,
Both the gate 30b and the resin outlet 32a are securely closed. Further, since the areas of both end surfaces of the slide nozzle 32 are equal, the force for pushing the slide nozzle 32 may be a slight force sufficient to close the gate 30a. Next, when the fluid cylinder 34 is retracted (to the right), the resin outlet 32a of the slide nozzle 32 is opened first, and then the right end surface of the spring 32b of the slide nozzle 32 contacts the flange portion 35a of the needle pin 35, The needle pin 35 is moved to a fixed position (position in FIG. 2). The positioning at this fixed position may be performed by bringing the arm 33 into contact with the end surface of the elongated hole 31a of the nozzle guide 31, or by the stop position of the fluid cylinder 34. In this state, the molten resin flows in the direction of arrow C to perform molding. After injecting for a fixed time, fluid cylinder 3
4 is advanced to close the resin outlet 32a and the gate 30b, and after cooling, the mold is opened to take out the product.

Second Embodiment As shown in FIG. 4, in place of the fluid cylinder 34 of the first embodiment which is externally attached as a separate member, a fluid cylinder 36 incorporated in the nozzle guide 31 is a slide nozzle. The needle pin 35 is opened and closed by directly moving the needle pin 3 forward and backward, and the needle pin 3 is moved by moving the slide nozzle 32 forward and backward.
The operation of No. 5 is the same as that of the first embodiment.

In the case of the third embodiment, the fluid cylinder 4 is provided with the needle pin 43 through the arm 44.
5, the valve element at the tip of the needle pin 43 closes the gate 30b of the sprue 30, and the through hole of the nozzle 41 is closed by the needle pin 43, as shown in FIG. When the needle pin 43 is retracted by the fluid cylinder 45, the gate 30b is first opened, then the inlet of the groove 43a of the needle pin 43 is opened, and the state shown in FIG. 6 is obtained, and the molten resin flows in the direction of arrow G. In addition,
The procedure of injection molding is similar to that of the first embodiment.

In the case of the fourth embodiment In FIG. 5, since the end surface E (two-dot chain line) of the nozzle 41 is replaced by F (solid line), there is no corner where the resin flow is bad, and At the time of replacement, the old resin can be easily replaced with the new resin, and the old resin can be prevented from remaining.

[0016]

As described above in detail, according to the present invention, the temperature of the molding machine changes over a wide range due to the presence of the grooves provided in the slide nozzle and the needle pin, and the length of the needle pin varies due to the difference in thermal expansion. Even if the length is shorter than the corresponding sprue and nozzle side, the sprue gate and the resin outlet of the nozzle can be reliably closed at the same time, and conversely, even if the needle pin length becomes long, No excessive force is applied and there is no risk of damage. Further, by making the shape of the tip of the nozzle an arc-shaped end surface, the corner portion where the resin does not flow well can be eliminated, the resin can be easily replaced, and the problem that the old resin remains can be solved. Further, the structure of the needle pin and its surroundings is simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part (when a nozzle is closed) of a shut-off nozzle according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part (when the nozzle is open) of the shut-off nozzle according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA of FIG.

FIG. 4 is a sectional view of an essential part (when the nozzle is closed) of a shut-off nozzle according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a main part (when the nozzle is closed) of the shut-off nozzle according to the third and fourth embodiments of the present invention.

FIG. 6 is a sectional view of a main part (when the nozzle is open) of the shut-off nozzle according to the third and fourth embodiments of the present invention.

7 is a sectional view taken along line D-D in FIG.

FIG. 8 is a sectional view of a conventional gate opening / closing device for a pre-chamber type mold.

[Explanation of symbols]

 30 Sprue 30a Resin Reservoir 30b Gate 31 Nozzle Guide 31a Long Hole 31b Cylinder Chamber 32 Slide Nozzle 32a Resin Outlet 32b Splash 32c Piston 33 Arm 34 Fluid Cylinder 35 Needle Pin 35a Flange 36 Fluid Cylinder 41 Nozzle 42 Torpedo 43 Needle Pin 43a groove 44 arm 45 fluid cylinder

Claims (4)

[Claims] 1. A nozzle guide that abuts against a sprue of a mold so as to form a resin reservoir, and a slide nozzle slidably fitted in the nozzle guide and having a resin outlet in the center. The slide nozzle is slidably held within a certain distance in the axial direction, and a needle pin having a valve for closing a gate provided on the sprue at a front end and a valve for closing a resin outlet of the slide nozzle at a rear end, A shut-off nozzle for an injection molding machine, comprising a fluid cylinder for moving the slide nozzle forward and backward through an arm. 2. A nozzle guide that abuts against a sprue of a mold so as to form a resin reservoir, and a slide nozzle that is slidably fitted in the nozzle guide and has a resin outlet in the center. The slide nozzle is slidably held within a certain distance in the axial direction, and a needle pin having a valve for closing a gate provided on the sprue at a front end and a valve for closing a resin outlet of the slide nozzle at a rear end, A shut-off nozzle for an injection molding machine, comprising a fluid cylinder for moving the slide nozzle forward and backward, wherein a part of the nozzle guide is an outer cylinder and a part of the slide nozzle is a piston. . 3. A nozzle guide that abuts against a sprue of a mold so as to form a resin reservoir portion, and a valve that is slidably fitted into the nozzle guide and closes a gate provided at the tip of the sprue. , A needle cylinder having a plurality of grooves serving as a resin outlet passage in the middle portion, and a fluid cylinder for moving the needle pins forward and backward through an arm, and when the needle pins advance, the plurality of grooves form a nozzle. A shut-off nozzle for an injection molding machine, which is configured so as to be closed by the wall surface of the hole. 4. The injection according to claim 3, wherein the shape of the tip end surface of the nozzle facing the resin reservoir is formed so as to sequentially project in an arc shape as it goes away from the inner peripheral portion in the outer peripheral direction. Shut-off nozzle of molding machine.