JPH08300418A - Injection molding die - Google Patents

Abstract

PURPOSE: To provide an injection molding die in which resin flows uniformly into a cavity, and a pressure loss is reduced and which can give a high quality molded product. CONSTITUTION: A movable die 3 which can advance/back to/from a fixed die 2 is provided, and a cavity 35 is formed between the dies 2, 3. A resin injection port, a resin passage 25a which communicates with the port, and a ring-shaped gate 30 which communicates with the passage 25a and leads molten resin to the cavity 35 are installed. In addition, a sleeve guide needle 31 is installed which is bonded/supported to/by a cavity core 36 which penetrates the passage 25a and the gate 30 and forms the cavity by its end part, and a sleeve valve 33 which opens/closes the gate 30 freely advansingly/backingly in the axial direction is engaged with the needle 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die suitable for molding a tubular molded product.

[0002]

2. Description of the Related Art An injection mold for molding a cylindrical molded product, such as a syringe of a syringe, which is a long and thin cylindrical body having a bottom at one end thereof, is used for molding one unit. The mold is provided with a plurality of cavities, and the molten resin injected from the molten resin injection port is distributed and guided to a gate communicating with the cavities in a heat-retaining state.

This injection molding die is constructed so that a plurality of molded products can be simultaneously molded by one injection molding. Basically, one molten resin is provided in the sprue portion provided in the central portion. It has an inlet and a branch passage communicating with the inlet and branched into a plurality of branches. On the other hand, the mold body is provided with a plurality of cavities, and a plurality of nozzle holder units having a gate communicating with these cavities are provided. Further, in order to connect the branch passage of the sprue portion and each of the nozzle holder units, a hot runner manifold having a heater is connected to guide the injected molten resin in a heat retaining state.

Therefore, the molten resin injected from the molten resin injection port is distributed to the plurality of runners through the branch passages, guided from the runners to the gate through the plurality of nozzle holder units, and further, from the gate to each cavity. Is injected into.

By the way, a conventional multi-gate injection molding die is constructed as shown in FIG. That is, 1 is a mold body, which is composed of a fixed mold 2 and a movable mold 3, and a plurality of cavity plates 4a and cavity cores 4b (having the same structure) are provided between the molds 2 and 3. Therefore, only one cavity 4 is formed). The fixed mold 2 has a base plate 10 on the upper part. A support plate 11 forming a space a is joined to the lower surface side of the base plate 10. A cylindrical hot runner manifold 13 having a resin passage 12 through which molten resin flows is provided in the space a. The hot runner manifold 13 is provided with a heater (not shown) and a molten resin injection port (not shown) for the molten resin.

A fitting hole 12a is formed in the hot runner manifold 13 at a right angle to the resin passage 12 and communicates with the end portion. The fitting hole 12a opens on the upper surface of the hot runner manifold 13 and communicates with the space portion a.

A flange 20a is provided at the upper end of the fitting hole 12a.
The valve guide bush 20 having the above is inserted, and the flange 20a is sandwiched between the base plate 10 and the hot runner manifold 13.

A resin communication passage 20b bent at a right angle is formed at the lower end of the valve guide bush 20.
One end of the resin communication passage 20b opened to the side of the valve guide bush 20 communicates with the resin passage 12, and the other end of the resin communication passage 20b opened to the bottom is the fitting hole 12a.
Is communicated with the resin passage 12c formed at the bottom of the.

The support plate 11 facing the resin passage 12c is provided with a nozzle holder 25 extending to the cavity plate 4a. The nozzle holder 25 has an upper end communicating with the resin passage 12c and a lower end via a gate 26. A resin passage 25a communicating with the cavity 4 is provided. Further, the band heater 2 is attached to the nozzle holder 25.
7 is wound, and is configured to guide the molten resin in a heat retaining state to a gate 26 provided at the center of the bottom of the molded product.

A valve guide hole 21 is formed in the axis of the valve guide bush 20, and a needle valve 22 is slidably supported in the valve guide hole 21 in the vertical direction. The needle valve 22 is a straight rod-shaped body, extends through the resin passage 25a of the nozzle holder 25 to the gate 26, and has a valve portion 22a at its lower end for opening and closing the gate 26.

An upper end portion of the needle valve 22 is connected to a valve operating piston 23a of an air cylinder 23 provided on the base plate 10 and is driven to move back and forth. When moving forward, as shown in FIG. When the gate is shut off and retracted, the gate 26 is opened so that the molten resin flows into the cavity 4 as shown in FIG.

[0012]

The injection molding die constructed as described above has a gate 26 at the center of the bottom of the molded product.
Is provided. Therefore, the needle valve 22 is retracted to open the gate 26, and at the same time, the resin passage 25a is opened.
Although the molten resin flows into the cavity 4 through the gate 26, the gate 26 is a single port, and the cavity 4 is a void that is in the shape of a molded product. It is hard to reach every corner.

Therefore, a biased resin pressure is applied to the cavity core 4b forming the cavity 4, and the cavity core 4b is tilted to generate a thick portion and a thin portion in the molded product,
In particular, in the case of an elongated cylindrical molded product such as a syringe of a syringe, since the cavity core 4b also becomes thin, there is a problem that the cavity core 4b easily tilts and the quality of the molded product varies. In addition, the gate 2 is on the bottom of the molded product.
Since 6 is located, there is a problem that a gate mark remains on the bottom of the molded product.

The present invention has been made in view of the above circumstances, and its purpose is to prevent the cavity core from inclining due to the injection of the molten resin and to prevent the gate mark of the molded product from remaining. An object of the present invention is to provide an injection mold capable of molding a high quality molded product.

[0015]

In order to achieve the above object, the present invention provides a fixed mold, a movable mold that can move forward and backward with respect to the fixed mold, and the fixed mold and the movable mold. A cavity formed between, a resin injection port provided in the fixed mold and a resin passage communicating with this, an annular gate provided in communication with the resin passage and guiding molten resin to the cavity, A sleeve guide needle penetrating the resin passage and the gate and having a tip end engaged with and supported by a cavity core forming the cavity, and a sleeve guide needle fitted to the sleeve guide needle so as to be movable back and forth in the axial direction to open and close the gate. And a sleeve valve that operates.

The cavity core is provided with an engaging concave portion, and the engaging concave portion is engaged with the engaging convex portion at the tip end portion of the sleeve guide needle. Further, the cavity core is provided with an engaging convex portion, and the sleeve guide needle has an engaging concave portion that engages with the engaging convex portion.

The sleeve guide needle is formed in a cylindrical shape and has a cooling medium flow passage formed therein. Further, the sleeve valve is characterized in that a tapered outer peripheral surface of a tip portion is formed, and the outer peripheral surface of the taper is brought into close contact with the inner peripheral surface of the nozzle when moving forward.

Further, the sleeve guide needle is characterized in that the shape of its tip portion forms a part of a molded product. Further, the sleeve guide needle has at least a distal end shape that is an irregular shape that forms an inner peripheral surface of the molded product,
The front end face of the sleeve valve that is fitted in the sleeve guide needle so as to move back and forth forms the end face of the molded product.

[0019]

According to the injection molding die having the above-described structure, the cavity core is engaged and supported by the sleeve guide needle even when the gate is opened and the molten resin flows into the gate and resin pressure is applied to the cavity core. Therefore, the inclination of the cavity core can be prevented.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. However, the same components as those of the prior art will be designated by the same reference numerals and the description thereof will be omitted. 1 and 2 show a first embodiment,
The principal part of a multi-gate injection molding die is shown. As shown in FIG. 1, a rod-shaped sleeve guide needle 31 is provided through the resin passage 25 a of the nozzle holder 25. The sleeve guide needle 31 has a base end portion which is a valve operating piston 23a of an air cylinder 23 for driving forward and backward.
Through the through hole 32 formed in the base plate 10
Is fixed to the engaging convex portion 31 having a tapered portion at its tip.
a is formed.

A cylindrical sleeve valve 33 is fitted in the sleeve guide needle 31 so as to be movable back and forth in the axial direction. The base end of the sleeve valve 33 is fixed to the valve operating piston 23a of the air cylinder 23 for advancing / retreating, and the front end extends to the gate 30 and has a tapered outer peripheral surface 33a.

The gate 30 is formed in an annular shape,
As shown in FIG. 2, the gate 30 is opened and closed by the front end surface of the sleeve valve 33. Further, the taper outer peripheral surface 33a of the sleeve valve 33 is formed at the same angle as the taper inner peripheral surface 34a of the nozzle 34 formed in the cavity plate 35a, and when the sleeve valve 33 advances, the taper outer peripheral surface 33a and the taper inner peripheral surface 33a. 34a is in close contact with the gate 34 to surely block the gate 30.

The cavity 35 is formed, for example, for molding a thin-walled cylindrical molded product, and comprises a large diameter portion 35a and a small diameter portion 35b, both of which are continuous by an inclined portion 35c. The top of the cavity core 36 forming the cavity 35, that is, the small diameter portion 35 of the cavity 35.
An engaging recess 36a is formed in a portion corresponding to b.

The engaging convex portion 31a of the sleeve guide needle 31 is engaged with the engaging concave portion 36a, and the cavity core 36 is supported by the sleeve guide needle 31. That is, although the cavity core 36 varies depending on the shape of the molded product, in the case of a slender cylindrical molded product, it becomes a slender cylindrical body, and since the base end is only fixed, the resin pressure injected into the cavity 35 is reduced. However, the sleeve guide needle 31 prevents this.

Next, the operation of the injection molding die configured as described above will be described. When the molten resin is injected from the nozzle of the injection molding machine into the molten resin injection port, the molten resin is guided to the resin passage 25a via the resin passage 12 of the hot runner manifold 13, and further to the nozzle 34 in that order. Since the tapered inner peripheral surface 34a and the tapered outer peripheral surface 33a of the sleeve valve 33 are in close contact with each other to block the gate 30, the molten resin is stopped at the nozzle 34 portion.

Therefore, when the valve operating piston 23a is operated to retract the sleeve valve 33 using the sleeve guide needle 31 as a guide, the valve portion 33a separates from the gate 30, and the annular gate 30 opens to open the resin passage 25a. The molten resin inside is filled in the cavity 35 through the gate 30. At this time, the resin pressure injected into the cavity 35 is applied to the cavity core 36,
The gate 30 has an annular shape, and the cavity core 36
Is supported by the sleeve guide needle 31, so that it does not tilt and the molten resin flows uniformly into the cavity 35.

When the filling of a predetermined amount of molten resin is completed, the valve operating piston 23a operates and the sleeve valve 3
3, the taper inner peripheral surface 34a of the nozzle 34 and the taper outer peripheral surface 33a of the sleeve valve 33 come into close contact with each other, and the gate 30 is shut off.

Therefore, there is no pressure loss and the molding cycle can be increased. Further, since the gate 30 has an annular shape and is injected from the end face of the molded product, there is no effect of leaving a gate mark on the molded product, and it is possible to mold a molded product of high quality.

FIG. 3 shows the obtained molded product, which is shown in FIG.
Is a syringe of a syringe, and FIG. 1B is a cylindrical body. Since resin is injected from the end surface of these molded products A as indicated by the arrow, no gate mark is left on the outer peripheral surface of the molded product A. An annular gate trace due to the annular gate remains on the end surface B of the molded product A to some extent, but since it is the end surface B, it is inconspicuous and can be seen as a part of the shape of the molded product A. FIG. 3C shows a molded product A in which the tip portion of the sleeve guide needle 31 functions as a cavity core to form the inner peripheral surface of the molded product A, and the tip surface of the sleeve valve 33 is a molded product. The end face of A is formed so that no trace of the gate remains.

FIG. 4 shows a second embodiment. The same components as those of the first embodiment are designated by the same reference numerals and their description is omitted. This example shows a main part of a direct gate type injection molding die. The base plate 10 is provided with a sprue bush 37, and the sprue bush 37 is provided with a molten resin injection port 38. And this molten resin injection port 3
8 communicates with the resin passage 25a of the nozzle holder 25 through a resin flow port 40 penetrating the wedge guide block 39.

Further, the wedge guide block 39 is provided with a lateral hole 41 and a vertical hole 42 orthogonal to the lateral hole 41. Two parallel wedges 43 are inserted in the lateral holes 41 so as to be able to move forward and backward, and these are driven by a hydraulic or pneumatic cylinder (not shown). The wedge 43 is provided with an inclined cam groove 44.

A cam pin 45 is interposed between the two wedges 43, and both ends thereof are slidably engaged with the cam groove 44. The middle portion of the cam pin 45 is formed to have a large diameter, and the sleeve guide needle 31 is formed in this large diameter portion.
Is provided with a through hole 46. Further, an elevating block 47 which can be moved back and forth in the vertical direction is inserted in the vertical hole 42, and a fitting hole 48 for fitting with a large diameter part of the cam pin 45 is provided at an upper end portion of the elevating block 47. There is. A concave portion 49 having a threaded portion on the inner peripheral surface is formed in the lower end portion of the elevating block 47, and a bush 50 is screwed into the concave portion 49.

A fitting hole 51 is formed in the bush 50 in the vertical direction, and a sleeve guide needle 31 and a sleeve valve 33 fitted in the sleeve guide needle 31 are inserted into the fitting hole 51. There is. A collar portion 52 is provided at the base end of the sleeve valve 33, and the collar portion 52 is hooked on the bush 50.

Although the gate 30 is shut off in the state shown in FIG. 4, the wedge 4 is turned on by a hydraulic or pneumatic cylinder.
When 3 is moved forward, the cam pin 45 engaged with the inclined cam groove 44 is pushed up, and the lifting block 47 is raised accordingly. Therefore, the bush 50 fixed to the lifting block 47 rises, and the sleeve valve 3
3 rises together. Then, the valve portion 33a is separated from the gate 30, the annular gate 30 is opened, and the molten resin inside the resin passage 25a is filled in the cavity 35 via the gate 30. At this time, the resin pressure injected into the cavity 35 is applied to the cavity core 36, but since the cavity core 36 is supported by the sleeve guide needle 31, it does not tilt and the cavity 3
The molten resin flows evenly in No. 5, and the same effects as those of the first embodiment are obtained.

FIG. 5 shows a third embodiment. The same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. FIG. 1A shows a main part of a multi-gate injection molding die,
FIG. 2B shows a main part of a direct gate type injection molding die. In this embodiment, the sleeve guide needle 53 is formed in a tubular shape, and the cooling medium flow passage 54 is formed inside.

The sleeve guide needle 53 of the multi-gate type injection molding die shown in FIG. 3A is provided with a cooling medium flow passage 54 penetrating the entire axial direction, and the base end portion of the sleeve guide needle 53 is It is fixed to the base plate 10. The base plate 10 is provided with a cooling medium port 55 such as cooling water or cooling air and communicates with the cooling medium flow passage 54 of the sleeve guide needle 53. Further, the engagement convex portion 53 a at the tip end portion of the sleeve guide needle 53 is engaged with the engagement concave portion 36 a of the cavity core 36, and the cooling medium is engaged with the concave concave portion 36 a of the cavity core 36 via the cooling medium flow passage 54. It has become available for distribution.

The sleeve guide needle 53 of the direct gate type injection molding die shown in FIG.
The base end of 3 is fixed to the sprue bush 37.
The sprue bush 37 is provided with a cooling medium port 56 such as cooling water or cooling air and communicates with the cooling medium flow passage 54 of the sleeve guide needle 53. Other configurations are the same as those of the multi-gate injection molding die, and the description thereof will be omitted.

FIG. 6 shows a fourth embodiment. In the third embodiment, the sleeve guide needle 53 and the sleeve valve 33 are formed in a cylindrical shape, but the present invention is not limited to this, and is constructed as follows. May be. That is, FIG.
Is a sleeve guide needle 53 having a rectangular cross section fitted with a sleeve valve 33 having an inner cavity having a rectangular cross section. FIG. 3B shows a sleeve guide needle 53 having a square cross section, and a sleeve valve 33 having a square cross section fitted therein. FIG. 7C shows a sleeve guide needle 53 having an elliptical cross section.
In addition, the sleeve valve 33 having a lumen with an elliptical cross section
Are fitted together.

FIG. 7 shows a fifth embodiment. In the fifth embodiment, a tapered outer peripheral surface 33a is formed at the tip of the sleeve valve 33, and the taper inner peripheral surface 3 of the nozzle 34 is cut off at the time of interruption.
Although the taper surface 33b and the straight surface 33c are formed on the outer circumference of the tip portion of the sleeve valve 33, the taper surface 34b is formed on the inner circumference of the nozzle 34 so as to be in close contact with the taper surface 33b and the straight surface 33c. And a straight surface 34c is formed.

FIG. 8 shows a sixth embodiment. In the above-described embodiment, an engaging projection 53a is provided at the tip of the sleeve guide needle 53, and an engaging recess 36 is provided in the cavity core 36.
Although the cavity core 36 is supported by providing "a" and engaging the engaging projection 53a with the engaging recess 36a, this embodiment provides the engaging recess 53b at the tip of the sleeve guide needle 53. Engagement protrusion 3 on cavity core 36
6b is provided, and the cavity convex portion 36b is engaged with the engagement concave portion 53b to support the cavity core 36. Further, in this embodiment, the case where the cooling medium flow passage 54 is provided in the sleeve guide needle 53 has been described, but also in the sleeve guide needle 31 having no cooling medium flow passage as in the first and second embodiments. Of course, it can be adopted.

FIG. 9 shows a seventh embodiment, in which the sleeve guide needle 60 has a deformed outer peripheral surface having a wavy cross section, and a cavity core 62 forming the inner peripheral surface of a molded product 61.
Is formed. The sleeve valve 63, which is fitted in the sleeve guide needle 60 so as to move back and forth, is basically a cylindrical body having the same shape as the sleeve guide needle 60, and the tip end surface 64 thereof forms the end surface of the molded product 61. According to this embodiment, after the sleeve valve 63 moves backward to inject the resin, the sleeve valve 63 moves forward and presses the end surface of the molded product 61, so that the molded product 61 having no gate mark can be molded. effective.

[0042]

The present invention has been configured as described above.
Even if the resin injection pressure is applied to the cavity core by the injection of the molten resin, the cavity core does not tilt, the resin uniformly flows into the cavity, there is little pressure loss, and it is possible to obtain a high-quality molded product with no variation. it can. Moreover, no gate marks are left on the molded product, and the cooling medium is introduced into the cavity core, whereby the molding cycle time can be shortened and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a main part of an injection molding die showing a first embodiment of the present invention.

FIG. 2 is an enlarged view of a gate portion of the embodiment, (a).
Is a vertical sectional front view, and (b) is a sectional view taken along the line AA.

FIG. 3 is a vertical sectional front view of the obtained molded product.

FIG. 4 is a vertical sectional front view and a vertical sectional side view of a main part of an injection molding die showing a second embodiment of the present invention.

5A and 5B show a third embodiment of the present invention, in which FIG. 5A is a vertical sectional front view of a main portion of a multi-gate injection molding die, and FIG. 5B is a vertical sectional view of a main portion of a direct gate injection molding die. Front view.

FIG. 6 shows a fourth embodiment of the present invention, (a) and (b)
(C) is a cross-sectional plan view of a valve guide needle and a sleeve valve having different shapes.

FIG. 7 is an enlarged vertical sectional front view of a gate portion showing a fifth embodiment of the present invention.

FIG. 8 is an enlarged view of a gate portion of a sixth embodiment of the present invention, (a) is a vertical sectional front view in a cutoff state, and (b) is a vertical sectional front view in an open state.

FIG. 9 shows a gate portion of a seventh embodiment of the present invention,
(A) is a vertical sectional front view, (b) is a cross-sectional plan view.

10A and 10B show a conventional injection molding die, in which FIG. 10A is a vertical sectional front view in a closed state, and FIG. 10B is a vertical sectional front view in an open state.

[Explanation of symbols]

2 ... Fixed mold, 3 ... Movable mold, 25a ... Resin passage, 30
... gate, 31 ... valve guide needle, 33 ... sleeve valve, 35 ... cavity, 36 ... cavity core.

Claims (7)

[Claims] 1. A fixed mold, a movable mold that can move forward and backward with respect to the fixed mold, a cavity formed between the fixed mold and the movable mold, and the fixed mold. A resin injection port and a resin passage communicating with the resin passage, an annular gate provided in communication with the resin passage for guiding molten resin to the cavity, and a tip end portion provided through the resin passage and the gate having the cavity. Injection-molding die, comprising: a sleeve guide needle engaged with and supported by a cavity core forming a cavity; and a sleeve valve that is fitted into the sleeve guide needle so as to be movable back and forth in the axial direction to open and close the gate. . 2. The cavity core is provided with an engaging concave portion, and the engaging convex portion at a tip end portion of the sleeve guide needle is engaged with the engaging concave portion. Injection mold. 3. The engagement protrusion is provided on the cavity core, and the tip of the sleeve guide needle has an engagement recess that engages with the engagement protrusion. 1. The injection mold according to 1. 4. The injection mold according to claim 1, wherein the sleeve guide needle is formed in a tubular shape, and a cooling medium flow passage is formed therein. 5. The injection according to claim 1, wherein the sleeve valve is formed with a tapered outer peripheral surface at a tip portion thereof, and the outer peripheral surface of the taper is brought into close contact with a tapered inner peripheral surface of the nozzle when advancing. Molding die. 6. The injection mold according to claim 1, wherein the sleeve guide needle forms a part of a molded product in a shape of a tip portion thereof. 7. The sleeve guide needle has a shape in which at least a tip end portion forms an inner peripheral surface of a molded product, and a tip end surface of a sleeve valve fitted to the sleeve guide needle so as to move back and forth is an end surface of the molded product. The injection molding die according to claim 1, wherein the injection molding die is formed.