JP7550064B2 - Shut-off nozzle device, injection device, injection molding machine, and shut-off nozzle driving method - Google Patents

Description

The present invention relates to a shut-off nozzle device that opens and closes an injection port using a needle valve, an injection device equipped with a shut-off nozzle, an injection molding machine, and a method for driving the shut-off nozzle.

The shut-off nozzle device is composed of an injection nozzle provided at the tip of the heating cylinder of the injection device, a needle valve that opens and closes the injection port of the injection nozzle, and a drive mechanism that drives the needle valve. Some shut-off nozzle devices have a needle valve that is coaxially provided within the resin flow path of the injection nozzle, as described in Patent Document 1, for example. Others have an oblique hole that connects the side of the injection nozzle to the resin flow path, and a needle valve provided in this hole. In either case, when the needle valve is driven by the drive device, the tip of the needle valve closes the resin flow path, i.e. the injection port, or opens the injection port.

JP 2008-296386 A

The drive mechanism of the shut-off nozzle device is supplied with compressed air or hydraulic oil at a preset pressure. In other words, the needle valve is driven by a fixed pressure. However, when the shut-off nozzle device is used for an extended period of time, resin accumulates in the insertion hole or injection port into which the needle valve is inserted, affecting the movement of the needle valve. This increases the time required to drive the needle valve, and there is even a risk that the needle valve will no longer be able to be driven.

This disclosure provides a shut-off nozzle device, an injection device, an injection molding machine, and a shut-off nozzle driving method that can smoothly drive a needle valve to open and close an injection port even after long-term use.

Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

This disclosure makes it possible to adjust the pressure of the fluid supplied to a piston-cylinder unit that drives a needle valve in a shut-off nozzle device. In other words, the pressure of the fluid is configured to be switchable between two or more levels.

According to the present disclosure, even if the needle valve becomes heavy due to long-term operation, the needle valve can be driven smoothly by increasing the fluid pressure.

FIG. 1 is a front view showing a vertical injection molding machine according to an embodiment of the present invention. 1 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a first embodiment of the present invention, which supplies hydraulic pressure to a piston-cylinder unit that drives a needle valve. FIG. 1 is a front cross-sectional view of an air-hydro booster according to the present embodiment, which is provided in a fluid supply device according to a first embodiment of the present invention. FIG. 4 is a front sectional view of an air-hydro booster according to another embodiment of the present invention. FIG. 11 is a front sectional view of an air-hydro booster according to still another embodiment of the present invention. 1 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a first embodiment of the present invention; 1 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a first embodiment of the present invention; 1 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a first embodiment of the present invention; 1 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a first embodiment of the present invention; 1 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a first embodiment of the present invention; 1 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a first embodiment of the present invention; 1 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a first embodiment of the present invention; 1 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a first embodiment of the present invention; FIG. 7 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a second embodiment of the present invention. FIG. 11 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a third embodiment of the present invention. FIG. 11 is a circuit diagram showing an air pressure circuit and a hydraulic circuit of a fluid supply device according to a fourth embodiment of the present invention.

Specific embodiments will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. To clarify the explanation, the following description and drawings have been simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary. In addition, hatching has been omitted in some areas to avoid cluttering the drawings.

The present embodiment will be described.
<Vertical injection molding machine>
As shown in Fig. 1, a vertical injection molding machine 1 according to this embodiment is generally composed of a mold clamping device 2 and an injection device 3. The injection device 3 is provided with a shut-off nozzle device 5 according to this embodiment, which will be described in detail later. The vertical injection molding machine 1 is provided with a controller 6, which controls the mold clamping device 2 and the injection device 3. The controller 6 also controls the shut-off nozzle device 5 according to this embodiment.

<Clamping device>
The mold clamping device 2 may be of a direct pressure type, and the type of mechanism for opening and closing the mold is not limited. The mold clamping device 2 according to the present embodiment is of a toggle type. That is, the mold clamping device 2 is composed of a fixed platen 9, an upper movable platen 11, a lower movable platen 12, tie bars 13, 13, ..., and a toggle mechanism 15. The fixed platen 9 is supported by a housing 8. The upper movable platen 11 is disposed above the fixed platen 9. The lower movable platen 12 is disposed below the fixed platen 9. The tie bars 13, 13, ... connect the upper movable platen 11 and the lower movable platen 12. The toggle mechanism 15 is provided between the fixed platen 9 and the lower movable platen 12. The fixed platen 9 and the upper movable platen 11 of such a mold clamping device 2 are provided with molds 16, 17. Therefore, when the toggle mechanism 15 is driven, the molds 16, 17 are clamped.

<Injection unit>
The injection device 3 is supported by a support column (not shown) relative to the upper movable platen 11. The injection device 3 is generally composed of a heating cylinder 18 and a screw 19 inserted in the heating cylinder 18. The screw 19 is adapted to be driven in the rotational direction and the axial direction by a driving device (not shown).

<Shut-off nozzle device>
The shut-off nozzle device 5 according to the present embodiment, which is provided in the injection device 3, will be described. The shut-off nozzle device 5 is composed of an injection nozzle 21, a needle valve 23, a piston cylinder unit 24, and a fluid supply device 26. The injection nozzle 21 is provided in the heating cylinder 18. The needle valve 23 is provided in the injection nozzle 21. The piston cylinder unit 24 drives the needle valve 23. The fluid supply device 26 supplies hydraulic oil to the piston cylinder unit 24. In this embodiment, the injection nozzle 21 has an oblique hole that communicates with the resin flow path from its side, and the needle valve 23 is inserted into this hole so as to be freely movable forward and backward. Therefore, when the piston cylinder unit 24 is driven to move the needle valve 23 forward, the tip of the needle valve 23 closes the injection port of the injection nozzle 21, and when the needle valve 23 is moved backward, the injection port is opened.

The piston cylinder unit 24 that drives the needle valve 23 is provided with multiple limiter switches 28. These limiter switches 28 are connected to the controller 6, which detects the forward and backward positions of the needle valve 23.

<Fluid Supply Device>
As will become clear from the following description, the greatest feature of the fluid supply device 26 constituting the shut-off nozzle device 5 according to this embodiment is that it can change the pressure of the fluid supplied to the piston cylinder unit 24 in at least two stages to change the force for driving the needle valve 23. The fluid supply device 26 that achieves this function can have various configurations. First, a fluid supply device 26A according to a first embodiment of this invention will be described with reference to FIG.

<Fluid Supply Device According to the First Embodiment>
In the fluid supply device 26A according to the first embodiment, the fluid supplied to the piston-cylinder unit 24 is hydraulic oil. However, in the fluid supply device 26A, the driving source is compressed air, which is converted into hydraulic pressure inside and supplied to the piston-cylinder unit 24. Fig. 2 is divided into upper and lower parts by a two-dot chain line, and the lower half of the divided part shows a compressed air circuit to which compressed air is supplied, and the upper half shows a fluid conversion means for converting compressed air into hydraulic pressure and a hydraulic circuit to which hydraulic pressure is supplied.

The compressed air circuit of the fluid supply device 26A according to the first embodiment includes an air source 31 that supplies compressed air, an FRL unit 32 consisting of an air filter (F), a regulator (R), and a lubricator (L), and a third solenoid switching valve 33. Downstream of the third solenoid switching valve 33, two pipelines are branched, and the third solenoid switching valve 33 switches between these pipelines. A first check valve 35 is provided in one of the branched pipelines, and a booster valve 36, an accumulator 37, and a second check valve 39 are provided in the other branched pipeline. As will be described later, the booster valve 36 and the accumulator 37 of the other branch serve as a first booster means for boosting the air pressure of the compressed air.

These two branched pipelines join downstream of the first and second check valves 35, 39 and are connected to the residual pressure relief valve 40. The residual pressure relief valve 40 is used to discharge compressed air remaining in the pipeline during maintenance, etc. The downstream of the residual pressure relief valve 40 branches into two pipelines, each of which is connected to the first and second solenoid switching valves 42, 43.

The downstream of the first solenoid switching valve 42 branches into two pipes, which are connected to the A and B ports of the first air-hydro booster 45 according to the present embodiment, which will be described next. Similarly, the downstream of the second solenoid switching valve 43 according to the present embodiment also branches into two pipes, which are connected to the A and B ports of the second air-hydro booster 46. In the first and second air-hydro boosters 45 and 46, the air pressure of the compressed air is converted into the hydraulic pressure of the hydraulic oil, and the hydraulic oil is supplied from each hydraulic line. These pipes are provided with first and second reverse regulators 48 and 49 with check valves, which are composed of a reverse regulator and a check valve, and first and second variable throttle valves 51 and 52 with check valves, which are composed of a variable throttle valve and a check valve. In addition, the first and second variable throttle valves 51 and 52 with check valves are connected to the A and B ports of the piston-cylinder unit 24, respectively.

The first and second solenoid switching valves 42, 43 are each provided with a line through which compressed air is discharged, and silencers 64, 64 are connected to these lines. Note that the third solenoid switching valve 33 and the first and second air-hydro boosters 45, 46, which will be described next, are also provided with lines and silencers through which compressed air is discharged, but these are omitted in FIG. 2.

<Air-hydro booster according to the present embodiment>
3A, the first and second air-hydro boosters 45, 46 according to this embodiment are composed of a large cylinder 53 and a small cylinder 54 which are connected to each other, and pistons 56, 57 provided in the large cylinder 53 and the small cylinder 54. These pistons 56, 57 are connected by a rod 58 so as to be driven integrally. An oil pot 60 is connected to the tip of the small cylinder 54 so as to supply hydraulic oil.

The first and second air-hydro boosters 45, 46 according to this embodiment are characterized in that a partition wall 59 is provided in the large cylinder 53. The large cylinder 53 is therefore divided into three areas: a first area 61 on the left side separated by the piston 56, a second area 62 separated by the piston 56 and the partition wall 59, and a third area 63 on the right side separated by the partition wall 59. The third area 63 is connected to the small cylinder 54. The first to third areas 61, 62, 63 are connected to the A port, the silencer 64, and the B port, respectively.

In the first and second air-hydro boosters 45, 46 according to this embodiment, when compressed air is supplied to the first area 61 from port A, the pistons 56, 57 are driven to the right in the figure, and the air pressure is converted into boosted hydraulic pressure. Also, when compressed air is supplied to the third area 63 from port B, the pistons 56, 57 are also driven to the right, and the air pressure is converted into equal pressure hydraulic pressure. In other words, the first and second air-hydro boosters 45, 46 according to this embodiment serve as second boosting means that converts air pressure into hydraulic pressure in two different stages.

<Function of the Fluid Supply Device According to the First Embodiment>
In the fluid supply device 26A according to the first embodiment, the first to third electromagnetic switching valves 42, 43, 33 are connected to a controller 6 (see FIG. 1), and the respective electromagnetic coils a, b are driven by commands from the controller 6. By the controller 6 operating the first to third electromagnetic switching valves 42, 43, 33, not only is it possible to switch the A and B ports to which hydraulic oil is supplied to the piston-cylinder unit 24, but it is also possible to switch the hydraulic pressure in multiple stages. In other words, not only is it possible to switch the direction of advance and retreat of the needle valve 23, but it is also possible to switch the driving force in multiple stages. This will be explained.

<Advance Operation of Needle Valve 23, First Stage Pressure>
4A, in the fluid supply device 26A according to the first embodiment, the electromagnetic coil b of the third solenoid switching valve 33 is driven, and the electromagnetic coil b of the first solenoid switching valve 42 is driven. Then, compressed air from the air source 31 is supplied to the B port of the first air-hydro booster 45 via the FRL unit 32, the third solenoid switching valve 33, the first check valve 35, the residual pressure release valve 40, and the first solenoid switching valve 42. The compressed air supplied to the B port is not boosted, so it has the air pressure supplied from the air source 31, for example, 0.5 MPa.

The hydraulic pressure is converted to hydraulic pressure equal to the air pressure in the first air-hydro booster 45. In other words, it is converted to hydraulic pressure of, for example, 0.5 MPa. This hydraulic oil passes through the first reverse regulator with check valve 48 and the first variable throttle valve with check 51, where the hydraulic pressure and flow rate are adjusted, and it is supplied to the A port of the piston-cylinder unit 24. This causes the needle valve 23 to move forward due to the first stage pressure. The injection port of the injection nozzle 21 (see Figure 1) is then closed.

<Advance Operation of Needle Valve 23, Second Stage Pressure>
In the fluid supply device 26A according to the first embodiment, as shown in Fig. 4B, the electromagnetic coil a of the third electromagnetic switching valve 33 is driven, and the electromagnetic coil b of the first electromagnetic switching valve 42 is driven. Then, compressed air from the air source 31 flows to the FRL unit 32, the third electromagnetic switching valve 33, the booster valve 36, and the accumulator 37. The compressed air from the air source 31 is boosted by the booster valve 36 to, for example, 1 MPa. This is adjusted to a stable air pressure by the accumulator 37, and is supplied to the B port of the first air-hydro booster 45 via the second check valve 39, the residual pressure release valve 40, and the first electromagnetic switching valve 42.

The boosted compressed air supplied to port B is converted to equal pressure hydraulic pressure in the first air-hydro booster 45. That is, it is converted to hydraulic pressure of, for example, 1 MPa. This hydraulic oil is supplied to port A of the piston-cylinder unit 24. In other words, the needle valve 23 moves forward due to the second stage pressure. The injection port of the injection nozzle 21 (see Figure 1) is closed.

<Forward Operation of Needle Valve 23, Third Stage Pressure>
In the fluid supply device 26A according to the first embodiment, as shown in FIG. 4C, the electromagnetic coil b of the third electromagnetic switching valve 33 is driven, and the electromagnetic coil a of the first electromagnetic switching valve 42 is driven. Then, the compressed air from the air source 31 is supplied to the A port of the first air-hydro booster 45 via the first electromagnetic switching valve 42 at an air pressure of, for example, 0.5 MPa without being boosted. The compressed air supplied to the A port is converted to a boosted hydraulic pressure in the first air-hydro booster 45. That is, the hydraulic pressure is converted to, for example, 7 MPa. This hydraulic oil is supplied to the A port of the piston-cylinder unit 24. That is, the needle valve 23 is advanced by the third-stage pressure. The injection port of the injection nozzle 21 (see FIG. 1) is closed.

<Advance operation of needle valve 23, fourth stage pressure>
In the fluid supply device 26A according to the first embodiment, as shown in FIG. 4D, the electromagnetic coil a of the third electromagnetic switching valve 33 is driven, and the electromagnetic coil a of the first electromagnetic switching valve 42 is driven. Then, the compressed air from the air source 31 is boosted by the booster valve 36 to, for example, 1 MPa. This compressed air is supplied to the A port of the first air-hydro booster 45 via the first electromagnetic switching valve 42. The compressed air supplied to the A port is converted to a boosted hydraulic pressure in the first air-hydro booster 45. That is, the hydraulic pressure is converted to, for example, 14 MPa. This hydraulic oil is supplied to the A port of the piston-cylinder unit 24. That is, the needle valve 23 is advanced by the fourth-stage pressure. The injection port of the injection nozzle 21 (see FIG. 1) is closed.

<Retraction operation of needle valve 23, first stage pressure>
4E, in the fluid supply device 26A according to the first embodiment, the electromagnetic coil b of the third electromagnetic switching valve 33 is driven, and the electromagnetic coil b of the second electromagnetic switching valve 43 is driven. Then, compressed air from the air source 31 is supplied to the B port of the second air-hydro booster 46 via the FRL unit 32, the third electromagnetic switching valve 33, the first check valve 35, the residual pressure release valve 40, and the first electromagnetic switching valve 42. Since the compressed air supplied to the B port is not boosted, it has the air pressure supplied from the air source 31, for example, 0.5 MPa.

The hydraulic pressure is converted to hydraulic pressure equal to the air pressure in the second air-hydro booster 46. In other words, it is converted to hydraulic pressure of, for example, 0.5 MPa. This hydraulic pressure is passed through the second check valve-equipped reverse regulator 49 and the second check valve-equipped variable throttle valve 52, where the hydraulic pressure and flow rate are adjusted, and then supplied to the B port of the piston-cylinder unit 24. This causes the needle valve 23 to move backwards due to the first stage pressure. The injection port of the injection nozzle 21 (see Figure 1) is opened.

<Retraction operation of needle valve 23, second stage pressure>
In the fluid supply device 26A according to the first embodiment, as shown in Fig. 4F, the electromagnetic coil a of the third electromagnetic switching valve 33 is driven, and the electromagnetic coil b of the second electromagnetic switching valve 43 is driven. Compressed air from the air source 31 flows to the FRL unit 32, the third electromagnetic switching valve 33, the booster valve 36, and the accumulator 37. The compressed air from the air source 31 is boosted by the booster valve 36 to, for example, 1 MPa. This is adjusted to a stable air pressure by the accumulator 37, and is supplied to the B port of the second air-hydro booster 46 via the second check valve 39, the residual pressure release valve 40, and the second electromagnetic switching valve 43.

The boosted compressed air supplied to port B is converted to equal pressure hydraulic pressure in the second air-hydro booster 46. That is, it is converted to hydraulic pressure of, for example, 1 MPa. This hydraulic oil is supplied to port B of the piston-cylinder unit 24, and the needle valve 23 is retracted by the second stage pressure. The injection port of the injection nozzle 21 (see Figure 1) is opened.

<Retraction operation of needle valve 23, third stage pressure>
In the fluid supply device 26A according to the first embodiment, as shown in FIG. 4G, the electromagnetic coil b of the third electromagnetic switching valve 33 is driven, and the electromagnetic coil a of the second electromagnetic switching valve 43 is driven. Then, the compressed air from the air source 31 is supplied to the A port of the second air-hydro booster 46 via the second electromagnetic switching valve 43 at an air pressure of, for example, 0.5 MPa without being boosted. The compressed air supplied to the A port is converted into boosted hydraulic pressure. That is, the hydraulic pressure is converted into, for example, 7 MPa. This hydraulic oil is supplied to the B port of the piston-cylinder unit 24, and the needle valve 23 is moved backward by the third-stage pressure. The injection port of the injection nozzle 21 (see FIG. 1) is opened.

<Retraction operation of needle valve 23, fourth stage pressure>
In the fluid supply device 26A according to the first embodiment, as shown in FIG. 4H, the electromagnetic coil a of the third electromagnetic switching valve 33 is driven, and the electromagnetic coil a of the second electromagnetic switching valve 43 is driven. Then, the compressed air from the air source 31 is boosted by the booster valve 36 to, for example, 1 MPa. This compressed air is supplied to the A port of the second air-hydro booster 46 via the second electromagnetic switching valve 43. The compressed air supplied to the A port is converted into boosted hydraulic pressure. That is, for example, it is converted into hydraulic pressure of 14 MPa. This hydraulic oil is supplied to the B port of the piston-cylinder unit 24, and the needle valve 23 is moved backward by the fourth-stage pressure. The injection port of the injection nozzle 21 (see FIG. 1) is opened.

<Operation method of shut-off nozzle device>
As described above, the fluid supply device 26A according to the first embodiment not only operates the forward and backward movement of the needle valve 23 by switching the first to third electromagnetic switching valves 33, 42, 43, but also changes the driving force for driving the needle valve 23 to four levels. The shut-off nozzle device 5 equipped with the fluid supply device 26A according to the first embodiment can be operated by various operating methods.

A typical operating method is to increase the driving force of the needle valve 23 in stages when the force required to drive the needle valve 23 increases. The needle valve 23 is inserted into a hole opened in the injection nozzle 21. When deteriorated resin accumulates in this hole due to long-term use, the sliding resistance of the needle valve 23 increases. In other words, the force required to drive the needle valve 23 increases. In the initial stage, the needle valve 23 is opened and closed with the first stage of driving force, and as the sliding resistance of the needle valve 23 increases due to long-term use, the driving force can be increased to the second, third, and fourth stages.

The increase in the sliding resistance of the needle valve 23 can be detected by a change in the time required to drive the needle valve 23. The controller 6 is configured to detect the completion of forward movement and the completion of backward movement of the needle valve 23 by a signal from the limiter switch 28. Therefore, the controller 6 monitors the time required from the start of driving the needle valve 23 to the completion of forward movement or backward movement. If these times exceed a preset specified time, or if the forward movement or backward movement is not completed, it is determined that the sliding resistance of the needle valve 23 has increased. In other words, the driving force of the needle valve 23 is increased in stages.

The shut-off nozzle device 5 according to this embodiment can be operated during resin color change or purging. Color change or purging may be performed with the resin temperature lowered. Lowering the resin temperature reduces the viscosity of the resin and increases the sliding resistance of the needle valve 23. In particular, a driving force is required when retracting the needle valve 23. Therefore, during color change or purging, the driving force is increased in stages only when retracting the needle valve 23.

<Air-hydro booster according to another embodiment of the present invention>
The air-hydro boosters 45 and 46 according to another embodiment of the present invention can be modified. Another embodiment is shown in FIG. 3B. In the air-hydro boosters 45' and 46' according to this embodiment, the piston 56 inserted in the large cylinder 53 is provided with a male rod 66 having a protrusion with a diameter smaller than that of the piston 56 by a predetermined length at the tip. On the other hand, the piston 57 inserted in the small cylinder 54 is provided with a female rod 67 having a hole with a predetermined depth in the axial direction at the end face. The male rod 66 and the female rod 67 are connected so that the protrusion is inserted into the hole. In the air-hydro boosters 45' and 46' according to this embodiment, when compressed air is supplied from the A port to the first area 61, the pistons 56 and 57 are driven to the right together. In the air-hydro boosters 45' and 46', when compressed air is supplied from the B port to the third area 63, only the piston 57 is driven to the right.

Figure 3C shows air-hydro boosters 45'', 46'' according to another modified embodiment. In this embodiment, a spring 69 is placed in a chamber containing hydraulic oil. When compressed air is supplied from port A to the first area 61 or from port B to the third area 63, pistons 56, 57 are driven against the elastic force of spring 69 to supply hydraulic oil. When compressed air is no longer supplied from port A to the first area 61 or from port B to the third area 63, pistons 56, 57 are returned to the left by the elastic force of spring 69.

<Fluid Supply Device According to the Second Embodiment>
The fluid supply device 26 according to the present embodiment shown in Fig. 1 can be modified in various ways. The fluid supply device 26A according to the first embodiment (see Fig. 2) needs to use air-hydro boosters with a special structure for the first and second air-hydro boosters 45, 46. Specifically, it is necessary to use an air-hydro booster with a partition wall 59 in a large cylinder 53, as shown in Figs. 3A to 3C. Alternatively, the fluid supply device 26 can be constructed from a commercially available air-hydro booster with a general structure. As an example of such a fluid supply device 26, a fluid supply device 26B according to a second embodiment is shown in Fig. 5.

In the fluid supply device 26B according to the second embodiment, the first and second air-hydro boosters 45x and 46x are commercially available air-hydro boosters of a general structure. These boost air pressure and convert it into hydraulic pressure, so they can be called third boosting means. However, the first and second air-hydro boosters 45x and 46x are provided with first and second air-hydro converters 71 and 72, respectively, instead of oil pots. In other words, they are provided with equal pressure conversion means that convert air pressure into equal pressure hydraulic pressure. And fourth and fifth solenoid switching valves 74 and 75 are provided to supply or cut off compressed air to the first and second air-hydro converters 71 and 72, respectively.

As will be easily understood by those skilled in the art, when the electromagnetic coil a is driven in the fourth electromagnetic switching valve 74, compressed air is supplied to the first air-hydro converter 71, converted into hydraulic pressure equal to the air pressure, and supplied to the A port of the piston-cylinder unit 24. The needle valve 23 advances due to the first or second stage pressure depending on the switching position of the third electromagnetic switching valve 33. On the other hand, when the electromagnetic coil a is driven in the fifth electromagnetic switching valve 75, compressed air is supplied to the second air-hydro converter 72, converted into hydraulic pressure equal to the air pressure, and supplied to the B port of the piston-cylinder unit 24. The needle valve 23 retreats due to the first or second stage pressure depending on the switching position of the third electromagnetic switching valve 33.

<Fluid Supply Device According to the Third Embodiment>
6 shows a fluid supply device 26C according to a third embodiment of the present invention, in which a commercially available air-hydro converter is used as the first and second air-hydro converters 45x, 46x. The first and second air-hydro converters 45x, 46x are provided with oil pots 60, 60 so that hydraulic oil is supplied to them. In this embodiment, third and fourth check valves 77, 78 are provided between the A ports and B ports of the first and second air-hydro converters 45x, 46x, respectively.

In the fluid supply device 26C according to the third embodiment, when the electromagnetic coil a of the first electromagnetic switching valve 42 is driven, the compressed air is supplied only to the A port of the first air-hydro booster 45x. That is, the air pressure of the compressed air is boosted and converted into hydraulic pressure. Depending on the switching position of the third electromagnetic switching valve 33, the third or fourth stage hydraulic pressure is supplied to the piston-cylinder unit 24, and the needle valve 23 is driven in the forward direction. However, when the electromagnetic coil b of the first electromagnetic switching valve 42 is driven, the compressed air is supplied not only to the B port of the first air-hydro booster 45x but also to the A port. Then, the air pressure of the compressed air is converted into equal hydraulic pressure in the first air-hydro booster 45x. That is, depending on the switching position of the third electromagnetic switching valve 33, the first or second stage hydraulic pressure is supplied to the piston-cylinder unit 24, and the needle valve 23 is driven in the forward direction.

This will be easily understood by those skilled in the art, so we will not go into detail here, but when the electromagnetic coil a of the second solenoid switching valve 42 is driven, the compressed air is converted into increased hydraulic pressure, and when the electromagnetic coil b is driven, the compressed air is converted into equal pressure hydraulic pressure, and the needle valve 23 is driven in the backward direction.

<Fluid Supply Device According to the Fourth Embodiment>
FIG. 7 shows a fluid supply device 26D according to a fourth embodiment, which is a modification of the fluid supply device 26C according to the third embodiment (see FIG. 6). The fluid supply device 26D according to the fourth embodiment differs from the fluid supply device 26C according to the third embodiment in that the third and fourth check valves 77 and 78 (see FIG. 6) are not provided, and the flow paths of the parts indicated by the reference numerals 79 and 80 in the first and second solenoid switching valves 42' and 43' are different. The fluid supply device 26D according to the fourth embodiment also exerts the same effect when operated in the same manner as the fluid supply device 26C according to the third embodiment. That is, when the electromagnetic coil b of the first solenoid switching valve 42' is driven, compressed air is supplied to the A port and the B port of the first air-hydro booster 45x. When the electromagnetic coil b of the second solenoid switching valve 42' is driven, compressed air is supplied to the A port and the B port of the second air-hydro booster 46x. That is, the fluid supply device 26D according to the fourth embodiment also achieves the same effect by performing the same operation as the fluid supply device 26C according to the third embodiment.

The shut-off nozzle device 5 according to this embodiment can be modified in various ways. For example, although the shut-off nozzle device 5 is provided in the vertical injection molding machine 1, it may be provided in a horizontal injection molding machine. In addition, the fluid that drives the piston cylinder unit 24 is described as hydraulic oil. However, other fluids such as compressed air may be used. Whatever fluid is used, it is sufficient that the pressure can be changed in two or more stages. Furthermore, the configuration of the injection nozzle 21 and the needle valve 23 can be changed. In this embodiment, the needle valve 23 is inserted into an oblique hole opened on the side of the injection nozzle 21, but as in the shut-off nozzle device described in Patent Document 1, the needle valve 23 may be provided coaxially with the injection nozzle 21 in the resin flow path of the injection nozzle 21.

The invention made by the inventor has been specifically described above based on the embodiments, but the present invention is not limited to the embodiments already described, and it goes without saying that various modifications are possible without departing from the gist of the invention. The multiple examples described above can also be implemented in appropriate combinations.

LIST OF SYMBOLS 1 Vertical injection molding machine 2 Mold clamping device 3 Injection device 5 Shut-off nozzle device 6 Controller 9 Fixed platen 11 Upper movable platen 12 Lower movable platen 13 Tie bar 15 Toggle mechanism 16 Mold 17 Mold 18 Heating cylinder 19 Screw 21 Injection nozzle 23 Needle valve 24 Piston cylinder unit 26 Fluid supply device 28 Limiter switch 31 Air source 32 FRL unit 33 Third solenoid switching valve 35 First check valve 36 Pressure booster valve 37 Accumulator 39 Second check valve 40 Residual pressure release valve 42 First solenoid switching valve 43 Second solenoid switching valve 45 First air-hydro booster 46 Second air-hydro booster 48 Reverse regulator with first check valve 49 Reverse regulator with second check valve 51 Variable throttle valve with first check valve 52 Variable throttle valve with second check valve 53 Large cylinder 54 Small cylinder 56 Piston 57 Piston 58 Rod 59 Partition wall 60 Oil pot 61 First area 62 Second area 63 Third area 64 Silencer 71 First air-hydro converter 72 Second air-hydro converter 74 Fourth solenoid switching valve 75 Fifth solenoid switching valve 77 Third check valve 78 Fourth check valve

Claims (17)

an injection nozzle provided at the tip of the heating cylinder;
a needle valve for opening and closing an injection port of the injection nozzle;
a piston-cylinder unit that drives the needle valve;
a fluid supply device that supplies a fluid to the piston-cylinder unit,
the fluid supply device is capable of supplying the fluid to the piston-cylinder unit by switching the pressure of the fluid in two or more stages so as to change the driving force of the needle valve . The shutoff nozzle device of claim 1, wherein the fluid supplied to the piston-cylinder unit is hydraulic oil. The shutoff nozzle device according to claim 2, wherein the fluid supply device is provided with a fluid conversion means for converting the pressure of the compressed air into the hydraulic pressure of the hydraulic oil. The shut-off nozzle device according to claim 3, wherein the fluid supply device is provided with a selectable first pressure boosting means, and when the first pressure boosting means is selected, the compressed air is boosted and supplied to the fluid conversion means. The shutoff nozzle device according to claim 3 or 4, wherein the fluid conversion means includes a second pressure boosting means, and the second pressure boosting means is capable of converting the pressure of the compressed air into hydraulic pressure at two or more different stages. The shutoff nozzle device according to claim 3 or 4, wherein the fluid conversion means is provided so as to be selectable between an isobaric conversion means and a third boosting means, and when the isobaric conversion means is selected, the pressure of the compressed air is converted into isobaric hydraulic pressure, and when the third boosting means is selected, the pressure of the compressed air is boosted and converted into hydraulic pressure. The shut-off nozzle device according to any one of claims 1 to 6, further comprising a controller, and configured to switch the pressure of the fluid to high pressure when the time required to drive the needle valve detected by the controller exceeds a specified time. The shut-off nozzle device according to any one of claims 1 to 6, wherein the pressure of the fluid is switched between when the needle valve is driven in the opening direction and when it is driven in the closing direction. A heating cylinder;
A screw provided in the heating cylinder;
a shut-off nozzle device provided at the tip of the heating cylinder;
The shut-off nozzle device includes an injection nozzle and
a needle valve for opening and closing an injection port of the injection nozzle;
a piston-cylinder unit that drives the needle valve;
a fluid supply device that supplies a fluid to the piston-cylinder unit,
the fluid supply device is capable of supplying the fluid to the piston cylinder unit by switching the pressure of the fluid between two or more stages so as to change the driving force of the needle valve . The injection device according to claim 9, wherein the fluid supplied to the piston-cylinder unit is hydraulic oil. The injection device according to claim 10, further comprising a fluid conversion means for converting the pressure of the compressed air into the hydraulic pressure of the hydraulic oil. A mold clamping device that clamps the mold;
an injection device that injects resin;
a shut-off nozzle device provided at a tip of the injection device,
The shut-off nozzle device includes an injection nozzle;
a needle valve for opening and closing an injection port of the injection nozzle;
a piston-cylinder unit that drives the needle valve;
a fluid supply device that supplies a fluid to the piston-cylinder unit,
the fluid supply device is capable of supplying the fluid to the piston-cylinder unit by switching the pressure of the fluid in two or more stages so as to change the driving force of the needle valve . The injection molding machine of claim 12, wherein the fluid supplied to the piston-cylinder unit is hydraulic oil. The injection molding machine according to claim 13, wherein the fluid supply device includes a fluid conversion means for converting the pressure of the compressed air into the hydraulic pressure of the hydraulic oil. An injection nozzle;
a needle valve for opening and closing an injection port of the injection nozzle;
a piston cylinder unit that drives the needle valve,
A method for driving a shut-off nozzle, comprising: switching the fluid supplied to the piston-cylinder unit between two or more stages to change the driving force of the needle valve . The method for driving a shutoff nozzle according to claim 15, wherein the fluid supplied to the piston-cylinder unit is hydraulic oil. 17. The method for driving a shut-off nozzle according to claim 16, further comprising the steps of: supplying compressed air, converting the pressure of the compressed air into the hydraulic pressure of the hydraulic oil, and supplying the hydraulic oil to the piston-cylinder unit.

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