JPH0999459A - Shutoff nozzle of injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the leakage of a resin and to prevent dragging by providing a piston ring on the outside of the outer peripheral surface of a rotary valve having a through-hole therein arranged on the way of a nozzle equipped with a molten resin passage and providing a spiral groove to the outer peripheral surface thereof and providing a revolving means allowing a molten resin passage to communicate with an edge end part and cutting of the same from the edge end part. SOLUTION: A shutoff nozzle 1 allows a rod 30a to advance to allow a through-hole 8 to communicate with a molten resin passage 10 and the rod 30a is allowed to retreat to cut off the through-hole 8 from a molten resin passage 10. Two pairs of piston rings having a rectangular cross section for preventing the leakage of a molten resin are axially arranged to the parts coming into contact with the first housings 39 of both end parts of a rotary valve 2 equipped with the shutoff nozzle 1. A region of an axial distance (a) is formed into a taper inclined surface S having a clearance (b) larger than the clearance (h) between the first housing 39 and a sleeve 8 at the edge end part and spiral grooves 60 are provided between the inclined surface S and two piston rings 6, 6.

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 an injection molding machine, and more particularly to a shut-off nozzle for an injection molding machine which prevents galling between the shut-off nozzle and a barrel housing and reduces resin leakage. It is a thing.

[0002]

2. Description of the Related Art Conventionally, an injection molding machine is provided with a shut-off nozzle that cuts off the passage of a molten resin when it is injected and filled into a mold cavity. FIG. 8 shows a shut-off nozzle 1 of a conventional injection molding machine, in which a cylindrical rotary valve 2 having a through hole 8 is arranged between an injection chamber and a nozzle tip opening, and a shutoff nozzle 1 is provided by a hydraulic cylinder. The rotary valve 2 is rotated by 90 degrees to disconnect the molten resin passage 10. At both ends of the rotary valve 2 of the shut-off nozzle 1, piston rings 6 for preventing resin leakage are arranged in a single row or a plurality of rows at appropriate intervals. Alternatively, the piston ring 6 may not be provided at all.

[0003]

However, such a conventional method has the following problems. (1) The back pressure of the screw during the measuring process is at most 100 to 2
Since the pressure is about 00 kg / cm ² , there is no problem with the sealing performance by 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, and further, from the end of filling. Immediately after the pressure-holding process is started, 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 to withstand the resin pressure and cause resin leakage. (2) Leaked molten resin adheres to the heater wiring of incidental equipment and causes a wire disconnection accident, and it is necessary to newly remove the adhered resin to prevent such a wire disconnection accident, which increases maintenance costs. I was invited. (3) Regarding lubrication of rotary valves, molten resin that leaks little by little usually plays a role of lubricant.
When a large amount of resin leaks as described above, the surface pressure between the rotary valve and the housing becomes abnormally high,
The rotary valve may be gnawed to hinder the smooth operation of the rotary valve, or in some cases, the rotary valve may not be able to rotate at all. As a countermeasure against this, if the clearance between the rotary valve and the housing is simply increased, the contradiction of increasing resin leakage will be encountered. (4) The rotation of the rotary valve is 4 during one molding cycle.
There are times. That is, there are four times, that is, opening to closing at the start of injection, opening to closing at the end of holding pressure, closing to opening at the start of suck back, and opening to close at the end of suck back. Of these, the pressure difference between the nozzle side (high pressure) and the screw side (atmospheric pressure) of the rotary valve is very large during the third operation (at the time of suck back start), and the rotary valve is rotated in this state. When power is applied, a large bending stress is generated, and deformation is caused to cause galling. Repeating this phenomenon damages the rotary valve and equipment such as a housing that comes into contact with the rotary valve.

[0004]

To solve the above problems, a shut-off nozzle of an injection molding machine is provided which can ensure a smooth operation of a rotary valve for a long time without abnormal resin leakage. Therefore, in the present invention, the first
In the invention of claim 1, a cylindrical rotary valve having a through hole inside and being rotatably fitted in the nozzle provided with a molten resin passage for guiding the molten resin from the injection molding machine into the mold cavity. Is provided, a piston ring wound around the outer peripheral surface of the rotary valve is provided, and rotation means for controlling communication between the molten resin passages is provided at an edge of the rotary valve. A spiral groove is formed on the outer peripheral surface. According to a second aspect of the present invention, in the first aspect of the present invention, a tapered inclined surface that reduces in diameter toward the end is formed at the edge of the outer peripheral surface of the rotary valve, and a spiral spiral groove is formed. did. Further, in the third invention, in the first invention or the second invention, the cross-sectional shape of the spiral groove is V-shaped, semicircular, or rectangular.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a nozzle having a molten resin passage for guiding molten resin from an injection molding machine into a mold cavity has a through hole inside and is rotatably fitted. A rotary means for arranging the mounted cylindrical rotary valve, providing a piston ring wound around the outer peripheral surface of the rotary valve, and controlling the communication of the molten resin passage at the edge of the rotary valve. With the provision of a spiral spiral groove on the outer peripheral surface of the rotary valve, the contact between the rotary valve and the housing becomes discontinuous, and friction heat generation between the rotary valve and the housing is reduced, and galling is reduced. High sealing performance is maintained, enabling stable operation for a long time.

[0006]

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 an injection nozzle having a shut-off nozzle, and FIG.
1 is a cross-sectional view taken along the line AA of FIG. 1, FIG. 3 is a vertical cross-sectional view of the shut-off nozzle, FIG. 4 is a cross-sectional view of a main part of a seal portion of the shut-off nozzle, and FIG. 5 is an enlarged cross-sectional view of the main part of FIG. 6 is a sectional view showing another embodiment of the seal portion, and FIG. 7 is a sectional view showing another embodiment of the seal portion.

In FIG. 1, the injection device 14 is provided with a heating cylinder 16, a nozzle 18 is attached to a heating cylinder head 17 at the tip of the heating cylinder 16 by a bolt 17a, and a screw 20 is freely rotatable in the heating cylinder 16. And is axially movable. 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). The tip of the nozzle 18 contacts the hot runner portion 24 formed in the die 22,
The molten resin passage 10 arranged in the nozzle 18 and the hot runner portion 24 are connected to each other to form a molten resin passage extending from the screw 20 to the hot runner portion 24.

Molten resin passage 1 provided in the nozzle 18
A shut-off nozzle 1 is disposed in the middle of 0, and nozzle opening / closing plates 26 are fixed to both ends of the shut-off nozzle 1. In addition, the nozzle opening / closing plate 26 is rotated about 90 degrees to move the shutoff nozzle 1 to about 9 degrees.
The shut-off nozzle drive device 28 causes the heating cylinder 16 to rotate so that the molten resin passage 10 can be blocked and the molten resin passage 10 can be disconnected from the pressure holding step to immediately start the next shot measuring step. Is disposed underneath. The shut-off nozzle drive device 28 includes a shut-off nozzle cylinder 30, a shut-off nozzle link plate 32, and a shut-off arm 34.

As shown in FIG. 1, one end of a shut-off nozzle link plate 32 having a substantially triangular shape is rotatably supported by a support shaft without movement, and a shut-off nozzle cylinder is provided at the other end. It is pin-joined to the tip end portion of the rod 30a of 30 and the shut-off arm 34, and is rotated around the support shaft. The other end of the shutoff arm 34 is pin-joined to the lower portion of the nozzle opening / closing plate 26 described above.

In this shut-off nozzle 1, hydraulic oil is supplied to the shut-off nozzle cylinder 30 to advance the rod 30a to move the through hole 8 through the molten resin passage 1.
It is configured such that the through hole 8 and the molten resin passage 10 are electrically disconnected from each other by retreating the rod 30a. Reference numeral 36 is a heater.

As shown in FIGS. 2 and 3, the shut-off nozzle 1 includes a sleeve 38, a first housing 39, a rotary valve 2, a second housing 42, and a sleeve pressing plate 4.
3, piston ring 6 and buffer ring 44. As shown in FIG. 3, a through hole 8 is formed in a direction orthogonal to the axis of the rotary valve 2. Sleeves 38 are fitted to both ends of the through hole 8, and a first housing 39 and a second housing 42 are fitted to the outer circumference of the rotary valve 2.

Sleeve pressing plates 43 fastened with bolts are provided on both sides of the first housing 39, and bushes 45 are fitted between sliding surfaces with the rotary valve 2 so that the sleeve 38 and the rotary valve 2 can be separated from each other. The key 46 is attached to. First housing 39 at both ends of the rotary valve 2
Two pairs of piston rings 6 having a rectangular cross section for preventing the leakage of the molten resin are arranged in the axial direction in a portion contacting with.

Also, the first housing 39 and the sleeve 38
In addition, as shown in FIGS. 4 and 5, an arrow-shaped buffer ring 44 is disposed so as to overlap the second housing 42 and the contact portion, and the buffer ring 44 is provided in the space 48 of the corresponding contact portion. The seal function is ensured by tightly engaging with each other.

FIG. 6 shows a conventional piston ring 6 which has a rectangular cross section and which has an abutment, and is arranged adjacent to each other in a superimposed manner. A single piston ring 6 is tilted by a resin pressure. However, in order to prevent the loss of the sealing property, they are configured so as not to tilt in cooperation with each other. In this case, in order to reduce the resin leakage from the abutment as much as possible, it is desirable to arrange the abutments 180 degrees apart from each other.

FIG. 7 shows not only the buffering 44,
A buffer ring 44 is also used in place of the piston ring 6 instead of the single piston ring 6, so that the sealing performance is further improved.

Next, the spiral groove 6 implemented in the present invention.
0 will be described. As shown in FIG. 4, the sleeve 38
The side of the outer peripheral surface facing the sleeve pressing plate 43 is formed so as to gradually reduce in diameter in the direction of the sleeve pressing plate 43, and the region of the axial distance a has the edge portion of the first housing 3
9 is formed on the tapered inclined surface S having a clearance b larger than the clearance h between the sleeve 38 and the sleeve 38, and a spiral spiral groove 60 is formed between the inclined surface S and the two piston rings 6, 6. Make a hole. The cross-sectional shape of the spiral groove 60 may be a semi-circular shape or a rectangular shape in addition to the V-shape shown in FIG. The spiral groove 60 is provided at both ends of the rotary valve 2, one of which is screwed in the forward screw direction and the other of which is screwed in the reverse screw direction. Further, it is desirable to apply an anti-seizure agent to the spiral groove 60 in advance prior to the operation, since it is possible to prevent the initial galling and to maintain the operation for a long time.

The operation of the shut-off nozzle of the injection molding machine of the present invention constructed as above will be described. First, the screw 20 is rotated and retracted by an appropriate distance, and then a predetermined amount of molten resin is stored in a storage portion in front of the screw 20 as a measuring step. At this time, it goes without saying that the shut-off nozzle 1 in the measuring step keeps the molten resin passage 10 blocked. In the injection process after the measurement process is completed, the shut-off nozzle 1 is put into a communication state, and then the molten resin stored in the storage portion is moved between the molds (not shown) by the forward movement (not rotating) of the screw 20. The cavity is injection-filled via the hot runner portion 24.

Simultaneously with the completion of the filling process and the pressure holding process, when the working oil is introduced into the shutoff nozzle cylinder 30, the rod 30a advances and the shutoff arm 34
Further, the shut-off nozzle 1 is rotated by about 90 degrees via the nozzle opening / closing plate 26, so that the molten resin passage is blocked. The shutoff nozzle 1 is the molten resin passage 1
When 0 is shut off, the screw 20 is rotated and retracted, and the measuring process is started again. On the other hand, the molten resin filled in the cavity occurs while being cooled by the mold,
In order to compensate for the shrinkage (in other words, sink mark) of the resin, the shut-off nozzle 1 is shut off and the hot runner 2 during the pressure-holding process.
The residual pressure in 4 applies pressure to the molten resin in the cavity during cooling for an appropriate time.

When the resin has been cooled and solidified by the mold for a certain period of time, the cooling process is completed, the mold is opened, the molded product is taken out, the mold is clamped again, and the shut-off nozzle 1 is in the communicating state. Then, the molten resin passage 10 is opened and the injection process is started. By repeating such a measuring process, an injection process, a pressure-holding process, and a cooling process (including the measuring process of the next shot during the cooling process), the injection pressure at the time of injection molding becomes, for example, 1000 kg / cm ^2. Alternatively, since a higher pressure is applied during the subsequent pressure-holding step, the conventional sealing mechanism using only the piston ring 6 causes leakage of the molten resin.
Note that the sequential operation of the molding cycle will be briefly described as follows. Mold open-shut off open-injection-holding pressure-shut off closed-
Cooling (simultaneous weighing) -shut-off opening-suckback-
Shut-off closed-mold open-product removal

In the embodiment of the present invention, the piston ring 6 and the buffer ring 44, in particular, are superposed in a position close to the through hole 8 to prevent the above-mentioned molten resin leakage.
As shown in FIGS. 4 and 5, the buffer ring 44 is inserted into the sleeve 38 and the first housing 39 in a normal state.
It is in a state of holding a minute gap between and. That is, the buffer ring 44 is not in contact with the sleeve 38 or the first housing 39, and moves to the left in the drawing only when the injection process is started to move to the space 48 and the buffer ring 4.
The shape of the arrow 4 is adapted to give a wedge effect to the contact surface to provide a sufficient seal. Further, the buffer rings 44 are arranged in a superposed manner so as to withstand a high resin pressure, and the buffer rings 44 themselves complement each other so as not to tilt.

The buffer ring 44 on the right side of FIG. 6 has a shape having a rectangular cross section, and since two buffer rings 44 are arranged adjacent to each other and the abutments are shifted by 180 degrees, tilting in one direction is prevented. It is possible to exert a higher sealing function. Similarly, the piston ring 6 on the right side of FIG. 7 has a rectangular cross section, and two adjacent piston rings 6 are arranged adjacent to each other with their abutments shifted by 180 degrees, so that they can be tilted in one direction. It is possible to prevent and exert a higher sealing function. By configuring the piston ring 6 and the buffer ring 44 in such a shape, a high sealing property is secured even with a high resin pressure of about 1000 kg / cm ² or more during injection molding or pressure holding process. It is possible to withstand continuous long-term operation about three times (6 months) as compared with the conventional single piston ring.

Further, on the outer peripheral surface of the sleeve 38, the side facing the sleeve pressing plate 43 is formed so as to be gradually reduced in diameter in the direction of the sleeve pressing plate 43 to form a tapered inclined surface S. By forming the spiral spiral groove 60 between the inclined surface S and the two piston rings 6, even if the molten resin flows outward beyond the piston ring 6, the molten resin is It flows along the spiral groove 60, and the sleeve 38 and the first
Since the surface pressure generated in the gap with the housing 39 is prevented from increasing more than necessary, galling of the sleeve 38 is prevented.
Further, by forming the outer peripheral surface end of the sleeve 38 in a tapered shape, even if the rotary valve 2 is slightly bent and deformed when the rotary valve 2 is rotated, the galling phenomenon due to this can be mitigated.

[0023]

As described above, in the present invention, the nozzle having the molten resin passage for guiding the molten resin from the injection molding machine into the mold cavity has a through hole therein and has a through hole. A cylindrical rotary valve that is movably fitted is disposed, a piston ring wound around the outer peripheral surface of the rotary valve is provided, and communication with the molten resin passage is cut off at the edge of the rotary valve. Since the turning means for controlling the rotary valve is provided and the spiral groove is formed on the outer peripheral surface of the rotary valve, the following excellent effects can be exhibited. (1) Since there is little resin leakage, resin removal work is unnecessary and maintenance is simple and easy. (2) Even when the resin pressure is high, by providing the spiral groove, the rotary valve and the housing are in discontinuous contact, frictional heat generation between them is small, and galling at the time of rotating the rotary valve can be prevented. (3) By providing tapered outer peripheral surfaces of both ends of the rotary valve and gradually increasing the clearances at the both ends, even if some deformation occurs during rotation of the rotary valve, the rotary valve smoothly rotates. It can be operated dynamically.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an injection nozzle including a shutoff nozzle according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is a vertical sectional view of a shutoff nozzle according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a main part of a seal portion of a shutoff nozzle according to an embodiment of the present invention.

5 is an enlarged cross-sectional view of the main parts of FIG.

FIG. 6 is a cross-sectional view showing another embodiment of the seal portion according to the embodiment of the present invention.

FIG. 7 is a cross-sectional view showing another embodiment of the seal portion according to the embodiment of the present invention.

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

FIG. 9 is a partial cross-sectional view of a conventional seal portion.

FIG. 10 is an enlarged cross-sectional view of a main part of a conventional seal part.

[Explanation of symbols]

 1 Shutoff Nozzle 2 Rotary Valve 4 Housing 6 Piston Ring 8 Through Hole 10 Molten Resin Passage 12 Gap 14 Injection Device 16 Heating Cylinder 18 Nozzle 20 Screw 24 Hot Runner 26 Nozzle Open / Close Plate 30 Shutoff Nozzle Cylinder 32 Shutoff Nozzle Link plate 38 Sleeve 39 First housing 42 Second housing 43 Sleeve retainer plate 44 Buffering 45 Bushing 46 Key 48 Space part (contact space part) 60 Spiral groove S Sloping surface h Clearance (gap 12) a Tapered slope surface length b Maximum clearance on taper slope

Claims (3)

[Claims] 1. A cylindrical rotary member having a through hole therein and rotatably fitted in the middle of a nozzle having a molten resin passage for guiding molten resin from an injection molding machine into a mold cavity. The rotary valve is provided with a piston ring wound around the outer peripheral surface of the rotary valve, and the rotary valve is provided at an edge of the rotary valve to shut off the communication of the molten resin passage. Shut-off nozzle for injection molding machines, which has spiral spiral grooves on the outer peripheral surface of the. 2. The injection according to claim 1, wherein a tapered inclined surface whose diameter decreases toward the end is formed at the edge of the outer peripheral surface of the rotary valve, and a spiral spiral groove is formed. Shut-off nozzle of molding machine. 3. The cross-sectional shape of the spiral groove is V-shaped, semicircular,
Alternatively, the shut-off nozzle of the injection molding machine according to claim 1 or 2, which has a rectangular shape.