JPH09123216A - Shutoff nozzle for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shutoff nozzle free from a resin leakage and capable of withstanding a long time of use by forming a cooling passage in parallel with the axial core direction, from both end parts to the center part, of each of a housing and a rotary valve. SOLUTION: The surroundings of a molten resin passage 10 is properly heated by a cartridge heater inserted into a heater mounting part 12 without disordering a normal melting and circulating process. However, if the remote surroundings of the molten resin passage 10 are heated by the cartridge heater, the viscosity of a resin is reduced, and the leakage of the resin easily occurs under the effect of rising of resin pressure at the time of starting dwelling. In order to prevent this phenomenon from occurring, cooling parts 33, 40 are provided in a rotary valve 2 and a housing 4 to cool only the remote peripheral part of the molten resin passage 10. Thus, a cooling passage 34 is arranged in parallel with the axial core running from both end parts to the center part of the rotary valve 2.

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 of an injection molding machine, and more particularly to prevention of resin leakage from the end of filling to the holding of pressure.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 8, a shut-off nozzle 1 of an injection molding machine is provided with a cylindrical rotary valve 2 having a through hole 8 between an injection chamber and a nozzle tip opening. This rotary valve 2 is moved to 90 by a hydraulic cylinder.
There is a shut-off nozzle 1 that is rotated between two positions, that is, a position where the molten resin passage 10 is connected and a position where the molten resin passage 10 is cut off.

In the conventional shut-off nozzle 1 described above, piston rings 6 for preventing resin leakage are arranged at both ends of the rotary valve 2 so as to be separated from each other by a plurality of rows.

[0004]

The shutoff nozzle 1 having the conventional piston ring 6 has the following problems.

The back pressure of the screw during the measuring process is at most 10
Since the pressure is about 0 to 200 kg / cm ² , there is no problem with the sealing performance of the piston ring 6 and it can withstand long-term use, but a resin pressure of about 500 kg / cm ² is applied during the injection process. Immediately after the start of the pressure-holding process, the resin pressure higher than that in the injection process is applied to the piston ring 6, and the piston ring 6 tilts or deforms and cannot withstand the resin pressure, and as shown in FIG. There was a problem that it leaked out from the gap.

[0006] The leaked molten resin adheres to the heater wiring, which is incidental equipment, and causes a disconnection accident, and it is necessary to remove the molten resin adhering to the wiring or the like each time, and the maintainability is poor. was there.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a shut-off nozzle which does not leak resin and can be used for a long time.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a housing is provided in the middle of a nozzle having a molten resin passage for guiding molten resin from an injection molding machine to a mold. , Having a through hole inside the housing,
In addition to providing a cylindrical rotary valve that is rotatably fitted, a piston ring wound around the outer peripheral surface of the rotary valve is provided, and a rotating means is provided at the end of the rotary valve to provide the melting. A shut-off nozzle of an injection molding machine configured to be rotatable between a connecting position and a shut-off position of a resin passage, the cooling being parallel to the axial direction from both ends of the housing and the rotary valve toward the center. In the second invention mainly including the passage, the bottomed portion is provided in the axial direction inside the cooling passage, and the inner cylinder is provided in the central portion of the cooling passage in a state of being slightly separated from the bottom portion. An annular passage is provided inside the cooling passage. In the third aspect of the invention, which is mainly based on the second aspect, the cooling passages are provided so as to face both end faces of the rotary valve, and a plurality of cooling passages are arranged in the circumferential direction of both end faces of the housing so as to be spaced apart from each other.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the peripheral portion of the rotary valve and the housing separated from the resin passage is cooled by providing the cooling portion, so that the temperature of the resin flowing through the resin passage is not changed. Cooling the outer periphery of the so-called shut-off nozzle portion prevents leakage of the molten resin from the resin passage.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

1 to 7 relate to the present invention, FIG. 1 is a sectional view of a main part of a seal portion of a shut-off nozzle, FIG. 2 is a front view of a housing arranged in an injection nozzle, and FIG. 3 is an outer shape of a rotary valve. FIG. 4 is a front view seen from AA of FIG. 3, FIG.
6 is an enlarged cross-sectional view of a cooling passage provided in the housing, FIG. 6 is a side view of an injection nozzle provided with a shut-off nozzle, and FIG. 7 is a lateral cross-sectional view taken along the line BB of FIG.

1 to 7, in the injection device 14, a nozzle 18 is attached to a heating cylinder head 17 fastened to the tip of a heating cylinder 16 by a bolt, and a screw 20 is rotatably mounted in the heating cylinder 16. Moreover, it is inserted so as to be movable in the axial direction. The rotation of the screw 20 is performed by a motor (not shown) connected to the rear portion of the screw 20, and the axial movement is operated by a hydraulic cylinder (not shown).

On the other hand, the tip of the nozzle 18 is in contact with the hot runner portion 24 formed in the die 22, and the molten resin passage 10 arranged in the nozzle 18 and the hot runner portion 24 are communicated with each other, and the screw 20 A molten resin passage reaching the hot runner portion 24 is formed. A shut-off nozzle 1 is arranged in the middle of the molten resin passage 10 provided in the nozzle 18, and both ends of the shut-off nozzle 1 are
The lever 26 is fixed. Then, move the lever 26 to about 40
By rotating the rotary valve 2 by about 40 degrees to block the molten resin passage 10, the rotary valve 2 is disconnected from the pressure-holding process so that the next shot measuring process can be started immediately. A shut-off nozzle drive device 28 is arranged in the lower part of the housing 4. The shut-off nozzle drive device 28 includes a shut-off nozzle cylinder 30.
And a lever 26 and a shut-off nozzle cylinder 30 which are pin-joined to a tip end portion of a piston rod 30a of the shut-off nozzle cylinder 30 via a connecting fitting 31.
Is formed of a bracket 50 or the like that is fixed to the housing 4.

The shut-off nozzle 1 is formed of a rotary valve 2 which is disposed in the middle of the nozzle 18 and is fitted inside the housing 4 and which rotates. More specifically, the shutoff nozzle 1 is composed of a rotary valve 2, a holding plate 3, a housing 4 and a piston ring 6. As shown in FIG. 1, a through hole 8 is formed in a direction orthogonal to the axial center of the rotary valve 2, and a housing 4 is fitted on the outer circumference of the rotary valve 2.

Holding plates 3 fastened with bolts are arranged on both sides of the housing 4, and piston rings 6 having a rectangular cross section for preventing leakage of molten resin are provided near both ends of the rotary valve 2. Are arranged in two pairs spaced apart in the axial direction.

In this embodiment, the heater mounting portion 1 is provided around the molten resin passage 10 without impairing the original melt flow.
It is adapted to be appropriately heated by a cartridge heater (not shown) inserted in 2. However, when the peripheral portion away from the molten resin passage 10 is heated by the cartridge heater, the viscosity of the resin is small, and the resin pressure is increased at the start of the pressure holding process, and the resin is likely to leak. To this end, as shown in FIG. 1, the rotary valve 2 and the housing 4 are provided with cooling portions 33 and 40 so that only the peripheral portion distant from the molten resin passage 10 is cooled.

As shown in FIG. 3, a cooling passage 34 is provided which is horizontal to the axis extending from both ends of the rotary valve 2 toward the center thereof. The cooling unit 33 has a circular outer perforated cooling pipe 35 having a bottom 33a and a cooling inner pipe 36 coaxially arranged inside the cooling outer pipe 35 so that an annular cooling passage 34 is formed. It is arranged.

The bottom portion 33a of the cooling outer cylinder 35 and the tip portion of the cooling inner cylinder 36 are slightly separated from each other. A cooling medium inlet 37 is provided on a side portion of the cooling inner cylinder 36, and further, a cooling outer cylinder 3 is provided.
5 has a refrigerant outlet 38 on the side thereof, and the refrigerant inlet 37 and the refrigerant outlet 38 are connected to a refrigerant introduction pipe and a refrigerant discharge pipe (not shown), for example, to pass a refrigerant such as industrial water or tap water. Or it can ventilate air.

On the other hand, as shown in FIG. 2, a plurality (eight in this embodiment) of cooling portions 40 are provided around both ends of the housing 4 around the molten resin passage 10. That is, as shown in FIG. 5, a cooling passage 34 that is horizontal to the axis extending from both ends of the housing 4 toward the center is provided. The cooling unit 40 has a circular outer perforated cooling cylinder 42 having a bottom portion 40a, and a cooling inner cylinder 43 coaxially arranged inside the cooling outer cylinder 42 to form an annular cooling passage 4.
1 is provided.

The bottom 40a of the cooling outer cylinder 42 and the tip of the cooling inner cylinder 43 are slightly separated from each other. A coolant inlet 44 is provided on a side portion of the cooling inner cylinder 43, and further, the cooling outer cylinder 4 is provided.
2 has a refrigerant outlet 45, and these refrigerant inlet 44 and refrigerant outlet 45 are connected to a refrigerant inlet pipe and a refrigerant outlet pipe (not shown), for example, to pass a refrigerant such as industrial water or tap water. Or it can ventilate air.

The operation of the shut-off nozzle of the injection molding machine of the present invention constructed as above will be described.

First, the housing 4 is mounted with the cartridge heater.
While heating the rotary valve 2, the cooling units 33, 4
A coolant is appropriately passed to 0 to cool the periphery of the molten resin passage 10. First, a desired molten resin is stored in a storage portion in front of the screw 20 by a measuring process in which the screw 20 is rotated and retracted by an appropriate length. The shut-off nozzle 1 is kept closed with the molten resin passage 10 during the clockwise amount process.

In the injection step following the metering step, the molten resin previously stored in the storage section is passed through the hot runner section 24 to the cavity section between the dies (not shown) by the forward movement (no rotation) of the screw 20. Is injected and filled.

When hydraulic oil is introduced into the shutoff nozzle cylinder 30 at the same time as the filling is completed, the rod 30a moves forward, and the shutoff nozzle 1 rotates about 40 degrees via the shutoff arm 34 and the nozzle opening / closing plate 26. As a result, the molten resin passage is blocked. When the shut-off nozzle 1 shuts off the molten resin passage 10, the screw 20 is rotated and retreated, and the metering process is started again.
On the other hand, in order to compensate for the shrinkage (in other words, sink mark) of the resin that occurs while the molten resin filled in the cavity is cooled by the mold, the shut-off nozzle 1 is shut off to prevent the hot resin during the pressure-holding process. The residual pressure in the runner portion 24 applies a predetermined pressure to the molten resin in the cavity during cooling. When the cooling and solidification of the resin by the mold for a certain period of time is completed, the cooling process ends, the mold is opened, the molded product is taken out, the mold is clamped again, and the shutoff nozzle 1 is restored to the communicating state. The molten resin passage 10 is opened to start the injection process.

In the present embodiment, the conventional housing 4 portion shown by the chain double-dashed line in FIG. 1 is cut and removed to the extent that the mechanical strength does not decrease, and the surface area is increased to promote heat dissipation. It has a large cooling capacity together with the cooling units 33 and 40 described above.

Further, a heat radiation fan may be disposed in the part of the chain double-dashed line removed by cutting to promote heat radiation.

[0027]

As is apparent from the above description, according to the present invention, the cooling portion for the cooling medium passage is provided in the rotary valve and the housing in the peripheral portion separated from the resin passage of the shutoff nozzle. Without changing the temperature (viscosity) of the molten resin flowing through the resin passage as in the conventional case, the temperature of the peripheral portion of the resin passage decreases and the temperature of the resin that is about to leak decreases, so that external leakage of the resin is prevented. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a seal part of a shut-off nozzle.

FIG. 2 is a front view of a housing arranged on an injection nozzle.

FIG. 3 is an external view of a rotary valve.

FIG. 4 is a front view as seen from AA of FIG.

FIG. 5 is an enlarged sectional view of a cooling passage provided in the housing.

FIG. 6 is a side view of an injection nozzle including a shutoff nozzle.

FIG. 7 is a horizontal cross-sectional view as seen from BB of FIG.

FIG. 8 is a vertical cross-sectional view of a conventional shutoff nozzle.

FIG. 9 is an explanatory diagram showing a leaked state of resin from a seal portion.

[Explanation of symbols]

 1 Shut-off nozzle 2 Rotary valve 4 Housing 6 Piston ring 8 Through hole 10 Molten resin passage 12 Heater mounting part 14 Injection device 16 Heating cylinder 18 Nozzle 20 Screw 24 Hot runner part 26 Lever 28 Shut-off nozzle drive device 30 For shut-off nozzle Cylinder 31 Connecting fitting 33, 40 Cooling part 33a, 40a Bottom part 34, 41 Cooling passage 35, 42 Cooling outer cylinder 36, 43 Cooling inner cylinder 37, 44 Refrigerant inlet 38, 45 Refrigerant outlet

Claims (3)

[Claims] 1. A housing is provided in the middle of a nozzle having a molten resin passage for guiding molten resin from an injection molding machine to a mold,
A cylindrical rotary valve having a through hole inside and rotatably fitted therein is provided, and a piston ring wound around the outer peripheral surface of the rotary valve is provided, and an end of the rotary valve is provided. A shut-off nozzle of an injection molding machine, which is configured to be rotatable between a connecting position and a shut-off position of the molten resin passage by providing a rotating means at a central portion from both end portions of the housing and the rotary valve. A shut-off nozzle for an injection molding machine, which is provided with cooling passages parallel to the axial direction of the shut-off nozzle. 2. The inside of the cooling passage according to claim 1, wherein a bottomed portion is provided in the axial direction inside the cooling passage, and an inner cylinder is arranged in a central portion of the cooling passage in a state of being slightly separated from the bottom portion. A shut-off nozzle for an injection molding machine, characterized in that an annular passage is provided in the. 3. An injection molding machine, wherein the cooling passage according to claim 2 is provided so as to face both end faces of the rotary valve, and a plurality of the cooling passages are arranged so as to be spaced apart from each other in the circumferential direction of the both end faces of the housing. Shut-off nozzle.