Extrusion device of multi-layer co-extrusion film blowing machine

Abstract

The invention discloses an extrusion device of a multi-layer co-extrusion film blowing machine, and particularly relates to the technical field of film blowing machines, the extrusion device comprises a co-extrusion die head, multiple extruders, an extrusion assembly, an adjusting assembly and an energy storage part, the extrusion assembly is arranged at one end of each extruder, and the extrusion assembly comprises a feeding part and an extrusion part; the adjusting assembly comprises an adjusting cylinder arranged at one end of the extrusion assembly, and the adjusting cylinder communicates with the feeding part and is used for adjusting pressure fluctuation in the feeding part. When the pressure fluctuation of the extrusion head is small, the volume of a cavity, communicating with the extrusion head, of the adjusting cylinder is changed according to the pressure in the extrusion head, so that the pressure in the extrusion head is changed; the problem of interlayer thickness ratio imbalance caused by fluctuation of internal pressure of the extrusion heads is prevented, and when the pressure fluctuation of the extrusion heads is large, the internal pressure of the other extrusion heads is adjusted in proportion according to the pressure fluctuation of the extrusion heads, so that the extrusion amount of each extrusion head is always kept in a certain proportion.

Description

Technical Field

[0001] The present invention relates to the technical field of film blowing machines, and more particularly to an extrusion device of a multi-layer co-extrusion film blowing machine. Background Art

[0002] A multi-layer co-extrusion film blowing machine is an advanced device that uses multiple extruders to co-extrude and compound various plastic melts in a specific ratio, then uses blow molding technology to produce functional films. Its core advantage lies in combining the characteristics of different materials to form multi-layer films with comprehensive properties such as high transparency, puncture resistance, high toughness, and moisture-proof properties. Suitable for food packaging, pharmaceutical packaging, and industrial heavy-duty packaging.

[0003] However, in the prior art, during the molten material extrusion molding process, the plastic melt needs to be fed into the barrel from the feed port, and while being heated inside the barrel, it is transported to the extrusion head of the extruder through the screw for extrusion. When wear occurs between the screw and the barrel, or the temperature of each section of the barrel is improperly set, resulting in melting too early or too late, it will cause pressure fluctuations of the melt at the extruder outlet, thereby causing the actual extrusion amount of the extruder to be unstable, and further causing the problem of imbalance in the thickness ratio between layers. When the pressure fluctuation lasts too long, it is necessary to stop the machine and adjust the barrel temperature or screw speed to change the pressure at the extruder outlet. Since adjusting the pressure will cause the extrusion amount to be unstable, it is necessary to stop multiple extruders and adjust them. At this time, the staff may need to re-pull the film, which is very inconvenient. Therefore, the present invention proposes an extrusion device for a multi-layer co-extrusion blown film machine to solve the above problems. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides an extrusion device of a multi-layer co-extrusion film blowing machine to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: an extrusion device of a multi-layer co-extrusion blown film machine, comprising: a co-extrusion die head, an extruder, an extrusion assembly, an adjustment assembly and an energy storage part, wherein there are multiple extruders, and the extrusion assembly is arranged at one end of the extruder, and the extrusion assembly includes a feed part and an extrusion part; the adjustment assembly includes an adjustment cylinder arranged at one end of the extrusion assembly, and the adjustment cylinder is connected to the feed part and is used to adjust the pressure fluctuation inside the feed part; the adjustment assembly also includes a storage cylinder arranged at one end of the extrusion assembly, and when the pressure of the feed part is abnormal, the storage cylinder can replace the feed part to supply material to the extrusion part; the energy storage part is arranged at one end of the co-extrusion feed part 31, and the energy storage part can store energy when the extruder pressure fluctuates, and provide pressure for the storage cylinder when the extruder pressure is abnormal.

[0006] Preferably, a first piston plate is provided inside the regulating cylinder, and the first piston plate divides the regulating cylinder into two chambers, one of which is connected to the feeding part and the other is connected to the energy storage part.

[0007] Preferably, a second piston plate is provided inside the storage barrel, and the second piston plate divides the storage barrel into two chambers, one of which is respectively connected to the feeding part and the extrusion part, and the other chamber is connected to the energy storage part.

[0008] Preferably, a first elastic member is provided inside the chamber communicating with the regulating cylinder and the energy storage part, one end of the first elastic member is fixedly connected to the first piston plate, and the other end of the first elastic member is fixedly connected to the bottom of the regulating cylinder.

[0009] Preferably, the feed part and the extrusion part are connected, and a pressure sensor for detecting the internal pressure of the feed part is provided at the connection point between the extrusion part and the feed part.

[0010] Preferably, a first exhaust hole is provided at the bottom of the regulating cylinder, a second air inlet hole is provided at one end of the energy storage part, the first exhaust hole and the second air inlet hole are connected, a first air inlet hole connected to the outside is provided at the bottom of the regulating cylinder, a one-way valve is provided at the first air inlet hole, and a one-way valve and an overflow valve are provided at the second air inlet hole.

[0011] Preferably, a third air inlet is provided at the bottom of the storage barrel, a second exhaust hole is provided inside the energy storage part, the second exhaust hole is connected to the third air inlet, and a pressure regulating valve is provided at the second exhaust hole.

[0012] Preferably, there are multiple second air inlet holes and they are respectively connected to the multiple first exhaust holes inside the regulating cylinder, there are multiple second exhaust holes and they are respectively connected to the multiple third air inlet holes inside the storage cylinder, and the exhaust pressure of the multiple second exhaust holes is adjusted by a pressure regulating valve to be equal to the rated pressure of the corresponding extruder.

[0013] Preferably, a feed hole is provided inside the storage barrel, the feed hole is connected to the feed part, a one-way valve is provided at the feed hole, a discharge hole is provided inside the storage barrel, the discharge hole is connected to the extrusion part, and a third exhaust hole connected to the outside is provided inside the storage barrel.

[0014] Preferably, a controller is provided at one end of the extruder, the pressure sensor is electrically connected to the controller by signal, a solenoid valve is provided at the connection point between the feed part and the extrusion part, a solenoid valve is provided at the discharge hole, a solenoid valve is provided at the third exhaust hole, and a solenoid valve is provided at the second exhaust hole. The connection point between the feed part and the extrusion part, the solenoid valve at the discharge hole, the solenoid valve at the third exhaust hole, and the solenoid valve at the second exhaust hole are all electrically connected to the controller by signal.

[0015] Technical effects and advantages of the present invention: The present invention changes the volume of the chamber connected to the extrusion head by adjusting the cylinder according to the pressure inside the extrusion head when the extrusion head generates pressure fluctuations, and stores energy in the energy storage part, thereby changing the pressure inside the extrusion head, thereby preventing the actual extrusion amount of the extruder from being unstable due to the fluctuation of the pressure inside the extrusion head, thereby causing the problem of imbalance in the thickness ratio between layers. When the pressure fluctuation of the extrusion head lasts for a long time, resulting in abnormal pressure, the energy storage part provides pressure to the storage cylinder according to the rated pressure of the extruder, so that the storage cylinder replaces the feeding part to feed the extrusion part, thereby ensuring that when the pressure of the extruder is adjusted, the extrusion amount of the extruder will not be affected by the pressure adjustment, and at the same time, it can still work together with other extruders. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0017] Figure 2 It is a schematic diagram of the overall structure of the extruder of the present invention.

[0018] Figure 3 It is a schematic cross-sectional structural diagram of the overall structure of the extrusion assembly of the present invention.

[0019] Figure 4 It is a schematic structural diagram of the co-extrusion feeding part 31 and the energy storage part of the present invention.

[0020] Figure 5 It is a schematic cross-sectional view of the structure of the second exhaust hole of the energy storage part of the present invention.

[0021] Figure 6 It is a schematic cross-sectional view of the overall structure of the energy storage part of the present invention.

[0022] The accompanying drawings are marked as follows: 1. co-extrusion die head; 2. extruder; 21. controller; 3. extrusion assembly; 31. feed part; 32. extrusion part; 321. pressure sensor; 4. adjustment assembly; 41. adjustment cylinder; 411. first piston plate; 412. first elastic member; 413. first exhaust hole; 414. first air inlet hole; 42. storage cylinder; 421. second piston plate; 422. third air inlet hole; 423. feed hole; 424. discharge hole; 425. third exhaust hole; 5. energy storage part; 51. second air inlet hole; 52. second exhaust hole. DETAILED DESCRIPTION

[0023] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0024] Example 1 In the actual production process, the melt at the extrusion port of the extruder 2 is prone to pressure fluctuations, which leads to instability in the actual extrusion volume of the extruder 2, and further causes an imbalance in the thickness ratio between layers. This embodiment is specially invented to solve the above problem.

[0025] See also Figures 1 to 6 As shown, an extrusion device of a multi-layer co-extrusion blown film machine according to an embodiment of the present invention includes a co-extrusion die head 1, an extruder 2, an extrusion assembly 3, an adjustment assembly 4 and an energy storage part 5. There are multiple extruders 2, and the extrusion assembly 3 is arranged at one end of the extruder 2. The extrusion assembly 3 includes a feed part 31 and an extrusion part 32; the adjustment assembly 4 includes an adjustment cylinder 41 arranged at one end of the extrusion assembly 3, and the adjustment cylinder 41 is connected to the feed part 31, and is used to adjust the pressure fluctuation inside the feed part 31; the adjustment assembly 4 also includes a storage cylinder 42 arranged at one end of the extrusion assembly 3, when the pressure of the feed part 31 is abnormal, the storage cylinder 42 can replace the feed part 31 to supply material to the extrusion part 32; the energy storage part 5 is arranged at one end of the co-extrusion feed part 31, and the energy storage part 5 can store energy when the pressure of the extruder 2 fluctuates, and provide pressure for the storage cylinder 42 when the pressure of the extruder 2 is abnormal.

[0026] See also Figure 3 and Figure 4 As shown, a first piston plate 411 is provided inside the regulating cylinder 41 , and the first piston plate 411 divides the regulating cylinder 41 into two chambers, one of which is connected to the feed part 31 and the other is connected to the energy storage part 5 .

[0027] See also Figure 3 As shown, a first elastic member 412 is provided inside the chamber connected to the regulating cylinder 41 and the energy storage part 5, one end of the first elastic member 412 is fixedly connected to the first piston plate 411, and the other end of the first elastic member 412 is fixedly connected to the bottom of the regulating cylinder 41. When the pressure of the feed part 31 increases, the first elastic member 412 is compressed, the volume of the chamber connected to the regulating cylinder 41 and the feed part 31 increases, and the molten material enters the chamber connected to the regulating cylinder 41 and the feed part 31. When the pressure of the feed part 31 decreases, the first elastic member 412 stretches, the volume of the chamber connected to the regulating cylinder 41 and the feed part 31 decreases, and the molten material enters the feed part 31 from the chamber connected to the regulating cylinder 41 and the feed part 31, wherein the first elastic member is a spring 412.

[0028] See also Figure 2 and Figure 3 As shown, the feed part 31 is connected to the extrusion part 32, and a pressure sensor 321 for detecting the internal pressure of the feed part 31 is provided at the connection between the extrusion part 32 and the feed part 31. When in use, the molten material enters the feed part 31 of the extrusion assembly 3 through the extruder 2. As the molten material continues to enter the feed part 31, the internal pressure of the feed part 31 continues to increase, and the molten material flows to the inside of the extrusion part 32. At the same time, part of the molten material enters the inside of the regulating cylinder 41, thereby compressing the first elastic member 412, thereby causing the first piston plate 411 to slide toward the bottom of the regulating cylinder 41. When the extrusion amount of the extrusion assembly 3 reaches the rated value, the pressure inside the feed part 31 is constant, and the first piston plate 411 no longer slides toward the bottom of the regulating cylinder 41. This is the normal working state of the extruder 2. When the pressure inside the extrusion assembly 3 fluctuates within a small range, when the internal pressure of the feed part 31 increases, the pressure on the first elastic member 412 increases, thereby causing the first piston plate 411 to continue to slide toward the bottom of the regulating cylinder 41, thereby causing The internal volume of the chamber connecting the regulating cylinder 41 and the extrusion component 3 increases, thereby increasing the amount of melt entering the regulating cylinder 41, thereby preventing the problem of increased extrusion volume due to increased internal pressure of the extrusion component 3; when the internal pressure of the extrusion component 3 decreases, the pressure on the first piston plate 411 decreases, thereby causing the first elastic member 412 to relax, thereby causing the first piston plate 411 to slide toward the top of the regulating cylinder 41 in the regulating cylinder 41 and squeeze the melt inside the regulating cylinder 41, thereby increasing the internal pressure of the feed part 31; by changing the volume of the chamber connecting the regulating cylinder 41 and the extrusion component 3 according to the pressure inside the feed part 31, the extrusion volume of the extrusion part 32 is kept stable, thereby preventing the actual extrusion volume of the extruder 2 from being unstable due to fluctuations in the internal pressure of the extrusion component 3, thereby causing the problem of imbalance in the thickness ratio between layers.

[0029] Example 2 In actual use, it was found that when the pressure fluctuation lasted too long, it was necessary to stop the machine and adjust the barrel temperature or screw speed to change the pressure at the extrusion outlet of the extruder 2. At this time, the staff may need to re-pull the film, affecting the work efficiency. Further improvements were made on the basis of the above embodiments.

[0030] See also Figure 3 As shown, a second piston plate 421 is provided inside the storage barrel 42, and the second piston plate 421 divides the storage barrel 42 into two chambers, one of which is respectively connected to the feed part 31 and the extrusion part 32, and the other chamber is connected to the energy storage part 5. When the extruder is working, part of the molten material enters the storage barrel 42 until the second piston plate 421 moves to the bottom end of the storage barrel 42.

[0031] See also Figure 3As shown, a first exhaust hole 413 is provided at the bottom of the regulating cylinder 41, and a second air inlet hole 51 is provided at one end of the energy storage part 5, the first exhaust hole 413 and the second air inlet hole 51 are connected, and a first air inlet hole 414 connected to the outside is provided at the bottom of the regulating cylinder 41, a one-way valve is provided at the first air inlet hole 414, and a one-way valve and an overflow valve are provided at the second air inlet hole 51, wherein the one-way valve and the overflow valve are both existing technologies and will not be elaborated here. When the first piston plate 411 moves toward the bottom of the regulating cylinder 41, the first piston plate 411 squeezes the gas inside the chamber connected to the regulating cylinder 41 and the energy storage part 5, so that it enters the energy storage part 5 through the first exhaust hole 413 and the second air inlet hole 51, wherein the first air inlet hole 414 can be connected to the atmosphere, and can also be connected to other gas sources according to actual working conditions, which is not limited here.

[0032] See also Figure 3 and Figure 6 As shown, a third air inlet 422 is provided at the bottom of the storage barrel 42, and a second exhaust hole 52 is opened inside the energy storage part 5. The second exhaust hole 52 is connected to the third air inlet 422. A pressure regulating valve is provided at the second exhaust hole 52, wherein the pressure regulating valve is a prior art and will not be elaborated here.

[0033] See also Figure 5 As shown, there are multiple second air inlet holes 51 and they are respectively connected to the multiple first exhaust holes 413 inside the regulating cylinder 41, and there are multiple second exhaust holes 52 and they are respectively connected to the multiple third air inlet holes 422 inside the storage cylinder 42. The exhaust pressure of the multiple second exhaust holes 52 is adjusted by a pressure regulating valve to be equal to the rated pressure of the corresponding extruder 2.

[0034] See also Figure 2 As shown, a feed hole 423 is opened inside the storage barrel 42, and the feed hole 423 is connected to the feed part 31. A one-way valve is provided at the feed hole 423. A discharge hole 424 is opened inside the storage barrel 42, and the discharge hole 424 is connected to the extrusion part 32.

[0035] See also Figure 3 As shown, a controller 21 is provided at one end of the extruder 2, the pressure sensor 321 is electrically connected to the controller 21, a solenoid valve is provided at the discharge hole 424, a third exhaust hole 425 connected to the outside is opened inside the storage barrel 42, a solenoid valve is provided at the third exhaust hole 425, and a solenoid valve is provided at the second exhaust hole 52. The solenoid valve at the discharge hole 424, the solenoid valve at the third exhaust hole 425 and the solenoid valve at the second exhaust hole 52 are all electrically connected to the controller 21, wherein the third exhaust hole 425 can be connected to the atmosphere, and can also be connected to other gas sources according to actual working conditions, which is not limited here.

[0036] On the basis of the above embodiment, when in use, the pressure inside the feed part 31 is detected in real time by the pressure sensor 321, and the detection information is transmitted to the controller 21. In the initial state, while the molten material is in the feed part 31, part of the molten material enters the interior of the storage barrel 42 until the second piston plate 421 moves to the bottom of the storage barrel 42, and part of the molten material enters the interior of the regulating barrel 41, so that the first elastic member 412 is compressed, thereby causing the first piston plate 411 to slide toward the bottom of the regulating barrel 41, thereby causing the gas in the chamber connected to the regulating barrel 41 and the energy storage part 5 to be squeezed, and the gas inside the chamber enters through the first exhaust hole 413 through the second air inlet hole 51. Inside the energy storage part 5, when the extrusion volume of the extrusion assembly 3 reaches the rated value, the pressure inside the feed part 31 is constant, and it is in normal working state at this time. When the pressure inside the feed part 31 fluctuates and causes the pressure to increase, the molten material enters the regulating cylinder 41, causing the first elastic member 412 to be further compressed, and more gas enters the energy storage part 5. When the pressure inside the feed part 31 fluctuates and causes the pressure to decrease, the first elastic member 412 stretches, causing the first piston plate 411 to slide toward the regulating cylinder 41, thereby allowing external gas to enter the chamber connected to the regulating cylinder 41 and the energy storage part 5. As the gas inside multiple extrusion assemblies 3 continuously enters the energy storage part 5, As a result, the gas in the energy storage part 5 is compressed, thereby increasing the internal pressure of the energy storage part 5. When the pressure sensor 321 detects that the pressure fluctuation time is long, the controller 21 controls the electromagnetic valves at the feed part 31 and the extrusion part 32 to close, and the molten material in the feed part 31 no longer enters the extrusion part 32. At the same time, the electromagnetic valve at the third exhaust hole 425 is controlled to close, and the electromagnetic valve at the discharge hole 424 and the electromagnetic valve at the second exhaust hole 52 are controlled to open. At this time, the gas inside the energy storage part 5 enters the storage barrel 42 through the second exhaust hole 52 and the third air inlet hole 422, thereby increasing the pressure at the bottom end of the storage barrel 42, squeezing the second piston plate 421 to move toward the top end of the storage barrel 42. The molten material in the storage barrel 42 enters the extrusion section 32 through the discharge hole 424, and the pressure of the extruder 2 is adjusted by the controller 21 at the same time. Since the exhaust pressure of the second exhaust hole 52 is equal to the rated pressure of the corresponding extruder 2, the molten material can still be extruded when entering the extrusion section 32. Therefore, when the pressure fluctuation of any extruder 2 lasts too long and it is necessary to stop the machine to adjust the barrel temperature or screw speed to change the pressure of the extrusion section 32 inside the extruder 2, the extrusion section 32 is fed with material through the storage barrel 42 to ensure that when the pressure of the extrusion section 32 of the extruder 2 is adjusted, multiple extruders 2 can still ensure the progress of film blowing.

[0037] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An extrusion device of a multi-layer co-extrusion film blowing machine, comprising a co-extrusion die head (1) and an extruder (2), wherein the extruder (2) is multiple, characterized in that: Also includes: An extrusion assembly (3), the extrusion assembly (3) being arranged at one end of the extruder (2), the extrusion assembly (3) comprising a feeding portion (31) and an extrusion portion (32); An adjusting component (4), the adjusting component (4) comprising an adjusting cylinder (41) provided at one end of the extrusion component (3), the adjusting cylinder (41) being in communication with the feed portion (31) and being used to adjust pressure fluctuations inside the feed portion (31); The regulating assembly (4) further comprises a material storage barrel (42) arranged at one end of the extrusion assembly (3); when the pressure of the feed portion (31) is abnormal, the material storage barrel (42) can replace the feed portion (31) to supply material to the extrusion portion (32); An energy storage unit (5) is provided at one end of the co-extrusion feed unit 31 (1), and the energy storage unit (5) is capable of storing energy when the pressure of the extruder (2) fluctuates, and providing pressure for the storage barrel (42) when the pressure of the extruder (2) is abnormal.

2. The extrusion device of the multi-layer co-extrusion film blowing machine according to claim 1, characterized in that: A first piston plate (411) is provided inside the regulating cylinder (41), and the first piston plate (411) divides the regulating cylinder (41) into two chambers, one of which is connected to the feed portion (31) and the other is connected to the energy storage portion (5).

3. The extrusion device of the multi-layer co-extrusion film blowing machine according to claim 2, characterized in that: A second piston plate (421) is provided inside the storage barrel (42), and the second piston plate (421) divides the storage barrel (42) into two chambers, one of which is respectively connected to the feeding part (31) and the extrusion part (32), and the other chamber is connected to the energy storage part (5).

4. The extrusion device of the multi-layer co-extrusion film blowing machine according to claim 3, characterized in that: A first elastic member (412) is provided inside a chamber communicating between the regulating cylinder (41) and the energy storage portion (5), one end of the first elastic member (412) is fixedly connected to the first piston plate (411), and the other end of the first elastic member (412) is fixedly connected to the bottom of the regulating cylinder (41).

5. The extrusion device of the multi-layer co-extrusion film blowing machine according to claim 4, characterized in that: The feeding portion (31) and the extrusion portion (32) are connected, and a pressure sensor (321) for detecting the internal pressure of the feeding portion (31) is provided at the connection point between the extrusion portion (32) and the feeding portion (31).

6. The extrusion device of the multi-layer co-extrusion film blowing machine according to claim 5, characterized in that: A first exhaust hole (413) is provided at the bottom of the regulating cylinder (41), a second air inlet hole (51) is provided at one end of the energy storage portion (5), the first exhaust hole (413) and the second air inlet hole (51) are connected, a first air inlet hole (414) connected to the outside is provided at the bottom of the regulating cylinder (41), a one-way valve is provided at the first air inlet hole (414), and a one-way valve and a relief valve are provided at the second air inlet hole (51).

7. The extrusion device of the multi-layer co-extrusion film blowing machine according to claim 6, characterized in that: A third air inlet (422) is provided at the bottom of the storage barrel (42), a second exhaust hole (52) is provided inside the energy storage portion (5), the second exhaust hole (52) is connected to the third air inlet (422), and a pressure regulating valve is provided at the second exhaust hole (52).

8. The extrusion device of the multi-layer co-extrusion film blowing machine according to claim 7, characterized in that: There are multiple second air inlet holes (51) and they are respectively connected to multiple first air exhaust holes (413) inside the regulating cylinder (41); there are multiple second air exhaust holes (52) and they are respectively connected to multiple third air inlet holes (422) inside the storage cylinder (42); the exhaust pressure of the multiple second air exhaust holes (52) is adjusted by a pressure regulating valve to be equal to the rated pressure of the corresponding extruder (2).

9. The extrusion device of the multi-layer co-extrusion film blowing machine according to claim 8, characterized in that: A feed hole (423) is provided inside the storage barrel (42), the feed hole (423) is connected to the feed portion (31), a one-way valve is provided at the feed hole (423), a discharge hole (424) is provided inside the storage barrel (42), the discharge hole (424) is connected to the extrusion portion (32), and a third exhaust hole (425) connected to the outside is provided inside the storage barrel (42).

10. The extrusion device of the multi-layer co-extrusion film blowing machine according to claim 9, characterized in that: A controller (21) is provided at one end of the extruder (2), the pressure sensor (321) is electrically connected to the controller (21), a solenoid valve is provided at the connection point between the feed portion (31) and the extrusion portion (32), a solenoid valve is provided at the discharge hole (424), a solenoid valve is provided at the third exhaust hole (425), and a solenoid valve is provided at the second exhaust hole (52). The connection point between the feed portion (31) and the extrusion portion (32), the solenoid valve at the discharge hole (424), the solenoid valve at the third exhaust hole (425), and the solenoid valve at the second exhaust hole (52) are all electrically connected to the controller (21).

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