JP2000094475A - Injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of unevenness or the defective molding caused by weld lines on a molding. SOLUTION: An injection molding machine is provided with a heating cylinder 21 provided movably forward and backward and to be set on both first and second positions, an injection nozzle 23 injecting resin in the heating cylinder 21 and a mold device 31 with a runner section feeding injected resin into a cavity space. The injection nozzle 23 is provided with a resin flow path to be shut off from the runner section when the heating cylinder 21 is set on the first position at the time of metering process, while to be communicated with the runner section when the heating cylinder 21 is set on the second position at the time of injection process. The resin flow path is shut off from the runner section at the time of metering process, and resin in the heating cylinder 21 is protected from leaking out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an injection molding machine.

[0002]

2. Description of the Related Art Conventionally, an injection molding machine has been used to devise a mold apparatus to be mounted, so that post-processing is not required, the work can be simplified, and automatic operation by multi-cavity can be performed. Enabled injection blow molding machines may be used. Various containers such as pharmaceutical containers, food containers, cosmetic containers and the like are manufactured by the injection blow molding machine.

[0003] In the injection blow molding machine,
An injection device equipped with a needle valve is used to ensure a high plasticizing ability of the resin. In the injection device, a pin-shaped needle valve is disposed inside a shut-off nozzle disposed at the tip, and the nozzle port is forcibly opened and closed by moving the needle valve forward and backward by, for example, a hydraulic cylinder. You can do it.

To this end, an operating lever is connected to the rear end of the needle valve, and the operating lever is swung by a hydraulic cylinder to move the needle valve forward and backward. FIG. 2 is a longitudinal sectional view of a main part of a conventional injection device, and FIG. 3 is a sectional view of a torpedo of the conventional injection device. As shown in the figure, the torpedo 13 is fixed to the rear end (the right end in FIG. 2) of the shut-off nozzle 11, and the heating cylinder 16 is fixed to the rear end of the torpedo 13. A screw 15 is rotatably and advancing and retracting in the heating cylinder 16. The screw 15 is retracted while rotating, so that the inside of the shut-off nozzle 11 in front of the screw 15 (left side in FIG. Can store resin. In order to send the resin in the heating cylinder 16 into the shut-off nozzle 11, a plurality of resin flow paths 18 are provided.
Is formed.

The front end of the shut-off nozzle 11 (FIG. 2)
A nozzle port 11a is formed at the left end of the nozzle port 11a, and the nozzle port 11a is opened and closed by moving the needle valve 12 forward and backward. To this end, the needle valve 12 is slidably supported by the torpedo 13, and an operation lever 14 is connected to the rear end of the needle valve 12.
When the operating lever 14 is swung by a hydraulic cylinder (not shown), the needle valve 12 can be moved forward and backward.

[0006]

However, in the conventional injection molding machine, since the needle valve 12 is provided at the center of the torpedo 13, the resin flow path 18 is provided around the needle valve 12. Although it is provided, a space 19 for connecting the needle valve 12 and the operation lever 14 is required, and therefore, as shown in FIG. 3, the resin flow passages 18 are uniformly provided in the circumferential direction. Can not do. Therefore, in the portion where the operation lever 14 is provided, the interval between the adjacent resin flow paths 18 becomes large.

In addition, since the heat of the resin is released to the atmosphere through the space 19, the temperature of the resin in the resin flow path 18 adjacent to the space 19 and the temperature of the other resin flow path 1
8 is different from the temperature of the resin. Therefore, the resin that has entered the shut-off nozzle 11 from each of the resin flow paths 18 branches and flows, or poor fusion occurs between the resins that have entered the shut-off nozzle 11.

As a result, the resin swells non-uniformly during blow molding, resulting in uneven thickness of the molded product and the occurrence of weld lines, resulting in poor molding. The present invention solves the problems of the conventional injection molding machine described above, resulting in uneven thickness of the molded product or the occurrence of a weld line,
An object of the present invention is to provide an injection molding machine that does not cause molding defects.

[0009]

For this purpose, in the injection molding machine of the present invention, the first and second injection molding machines are provided so as to be movable forward and backward.
A heating cylinder, an injection nozzle attached to the front end of the heating cylinder, for injecting the resin in the heating cylinder, and a runner section for supplying the resin injected from the injection nozzle to the cavity space. And a mold device.

The injection nozzle is shut off from the runner when the heating cylinder is placed at the first position during the measuring step, and the heating cylinder is placed at the second position during the injection step. A resin flow path that is communicated with the runner portion when it is inserted. In another injection molding machine of the present invention, the runner portion is formed in a hot runner.

[0011] In still another injection molding machine of the present invention,
Further, the first position is a retreat position of the heating cylinder, and the second position is a forward position of the heating cylinder.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a first state of an injection molding machine according to an embodiment of the present invention,
FIG. 4 is a view showing a second state of the injection molding machine according to the embodiment of the present invention, and FIG. 5 is a detailed view of the injection molding machine according to the embodiment of the present invention.

In the drawing, 21 is a heating cylinder, 22 is a screw arranged rotatably and advancing and retracting inside the heating cylinder 21, 23 is the heating cylinder 21
Is an injection nozzle having an open nozzle structure attached to the front end of the injection nozzle. The screw 22 extends rearward (to the right in the drawing) inside the heating cylinder 21 and is connected at the rear end to driving means (not shown). Therefore,
At the time of the weighing process, when the driving means is driven to retract (moving to the right in the drawing) while rotating the screw 22,
The pellet-shaped resin in the hopper (not shown) enters the heating cylinder 21, moves forward (moves to the left in the figure) in the groove 26, is melted by a heater (not shown), and is stored in front of the screw head 24. Can be

When the driving means is driven to advance the screw 22 during the injection step, the resin stored in front of the screw head 24 is injected from the injection nozzle 23. The heating cylinder 21, screw 22, injection nozzle 23, driving means and the like constitute an injection device. The injection nozzle 23 includes a heating cylinder 2
Large-diameter mounting portion 9 for mounting injection nozzle 23 to 1
1, a conical (conical) portion 92 formed forward of the mounting portion 91, and a small-diameter fitting portion 93 formed forward of the conical portion 92; In the shape part 92 and the fitting part 93, the heating cylinder 21
A first resin flow path 28 communicated with the inside and extending in the axial direction is provided inside the fitting portion 93 with the first resin flow path 28 and extends in the radial direction. Two resin flow paths 29 are respectively formed. And the fitting portion 9
3 has a structure in which the front end is closed and openings 94 and 95 are formed in the side wall near the front end.

A mold device 31 is provided in front of the injection device. The mold apparatus 31 includes a fixed mold assembly 32 and a movable mold assembly (not shown) disposed to be movable with respect to the fixed mold assembly 32. By doing so, mold closing, mold closing and mold opening can be performed. The fixed mold assembly 32 includes a fixed mold 33 that is brought into contact with and separated from the movable mold of the movable mold assembly, a receiving base 34 that supports the fixed mold 33, a spacer 35, a fixed platen 36, Cavity 4 held by stationary mold 33 and cradle 34
1. Nozzle 4 disposed adjacent to cavity 41
2, a hot runner 43 disposed adjacent to the nozzle 42, and an injection nozzle 2 with respect to the fixed platen 36.
3 and a nozzle receiver 44 for positioning the hot runner 43. A fitting hole 44a for fitting the injection nozzle 23 is formed in the nozzle receiver 44.

A space 47 is formed in the cavity 41 so as to correspond to the shape of a molded product (not shown).
When the core (not shown) attached to the movable mold enters the space 47 with the closing of the mold, a cavity space is formed between the cavity 41 and the core. A third resin flow path 48 is formed in the nozzle 42 in communication with the space 47, and a gate 49 is formed at the front end of the third resin flow path 48.

Further, in the hot runner 43, a first runner 51 extending in the axial direction intersects with the first runner 51 in order to supply the resin injected from the injection nozzle 23 to the cavity space. And extend in a direction perpendicular to the second
And a third runner portion 53 extending in the axial direction from the tip of the second runner portion 52 and communicating with the third resin flow path 48 is integrally formed.

The injection device is provided so as to be able to move forward and backward, and the heating cylinder 21 is also moved forward and backward as the injection device is moved forward and backward. By taking a retreat position as the first position shown and an advancing position as the second position shown in FIG. 4 and placing the heating cylinder 21 in the retreat position, the second resin flow path 29 and the second The second resin flow path 29 and the second runner section 52 can be communicated by shutting off the runner section 52 and the heating cylinder 21 at the forward position.

In order to move the heating cylinder 21 forward and backward, an injection device and a drive unit (not shown) are connected, and the drive unit is driven at a predetermined timing by a control device (not shown) to move the injection device forward and backward. Then, the heating cylinder 21 is placed at the retracted position during the measuring process, and is placed at the advanced position during the injection process. Therefore, in the measuring step, the second resin flow path 29 and the second runner 5
2, the resin in the heating cylinder 21 does not leak.

As a result, the screw 22 can be retracted at a high speed during the metering step, so that the molding cycle can be shortened. In addition, at the start of the measuring process, a pressure reducing action acts in the first to third runner sections 51 to 53 with the retreat of the heating cylinder 21. Therefore, there is no possibility of forming defects such as pulling yarn and cold slack.

Further, since it is not necessary to use a torpedo, not only does the resin flow uniformly in the first and second resin flow paths 28 and 29, but also the heat of the resin is released to the atmosphere during that time. Absent. Therefore, the first and second resin flow paths 2
There is no possibility that the resin branches and flows in the insides of the first and second resin flow paths and no defective fusion occurs between the resins in the first and second resin flow paths. As a result, the resin swells uniformly during blow molding, so that there is no uneven thickness in the molded product, no weld line, and no molding failure.

The present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0023]

As described above in detail, according to the present invention, in an injection molding machine, a heating cylinder which is disposed to be able to move forward and backward and takes first and second positions, and a front end of the heating cylinder And a mold device provided with a runner for supplying the resin injected from the injection nozzle to the cavity space.

The injection nozzle is shut off from the runner when the heating cylinder is placed at the first position during the measuring step, and the heating cylinder is placed at the second position during the injection step. A resin flow path that is communicated with the runner portion when it is inserted. In this case, at the time of the measuring step for plasticizing the plastic raw material, the runner section and the resin flow path are shut off, so that the resin in the heating cylinder does not leak.

As a result, in one molding cycle, the heating cylinder is placed at the second position except during injection (filling) and pressure holding, so that the metering step for plasticizing the plastic raw material is performed except during this time. Will be possible. Therefore, the injection molding machine has the same function as the injection molding machine equipped with the conventional needle valve nozzle. The cycle can be shortened.

Further, at the start of the measuring step, a depressurizing action acts in the runner section as the heating cylinder moves backward. Therefore, molding defects such as threading and cold slack do not occur. In addition, since it is not necessary to use a torpedo, not only does the resin flow uniformly in the resin flow path, but also the heat of the resin is not released to the atmosphere during that time. Therefore, there is no possibility that the resin branches and flows in the resin flow path, and no fusion failure occurs between the resins in the resin flow path. As a result, there is no uneven thickness of the molded product, no weld line, and no defective molding.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of an injection molding machine according to an embodiment of the present invention.
It is a figure showing the state of.

FIG. 2 is a longitudinal sectional view of a main part of a conventional injection device.

FIG. 3 is a sectional view of a torpedo of a conventional injection device.

FIG. 4 shows a second example of the injection molding machine according to the embodiment of the present invention.
It is a figure showing the state of.

FIG. 5 is a detailed view of the injection molding machine according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Heating cylinder 23 Injection nozzle 29 2nd resin flow path 31 Mold apparatus 43 Hot runner 51-53 1st-3rd runner part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F202 AG07 AH55 AM36 CA11 CB01 CK03 4F206 AG07 AH55 AM36 JA05 JA07 JL02 JM01 JM04 JN06 JQ57 JQ81

Claims (3)

[Claims] (A) First and second movable members are provided so as to be able to move forward and backward.
(B) an injection nozzle attached to the front end of the heating cylinder for injecting the resin in the heating cylinder, and (c) supplying the resin injected from the injection nozzle to the cavity space. (D) the injection nozzle is shut off from the runner portion when the heating cylinder is placed at the first position during the measuring step, and the injection nozzle is closed. An injection molding machine comprising: a resin flow path that is communicated with the runner when the heating cylinder is placed at the second position during the process. 2. The injection molding machine according to claim 1, wherein the runner section is formed in a hot runner. 3. The injection molding machine according to claim 1, wherein the first position is a retreat position of the heating cylinder, and the second position is a forward position of the heating cylinder.