Sealed kneading machine

Abstract

This sealed kneading machine is provided with: a kneading chamber having a kneading room; a material input portion positioned above the kneading chamber; a pair of kneading rotors configured to knead an object to be kneaded inside the kneading room; a weight disposed in the material input portion so as to press the object to be kneaded inside the kneading room from above; a hydraulic circuit having a hydraulic cylinder connected to the weight; and a controller for controlling the hydraulic circuit to perform a pressing operation that supplies hydraulic oil to the hydraulic cylinder so that the object to be kneaded is pressed by the weight, and a rapid-rise suppression operation that regulates the operation of the hydraulic cylinder so that the upward movement speed of the weight is suppressed when the pressing operation is released.

Description

Closed kneader

[0001] The present invention relates to a closed kneader.

[0002] Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 2007-54824, a closed kneader that kneads a kneaded material while pressing the kneaded material with a weight in a kneading chamber is known. In the kneader disclosed in Japanese Patent Application Laid-Open No. 2007-54824, a linear scale for detecting the lifting position of the weight and a position setter for setting the lifting position of the weight are provided. In this kneader, the lifting position control of the weight is executed so that the position of the weight matches the set value set by the position setter. Note that the position control of the weight is performed by ON / OFF control of an electromagnetic direction switching valve.

[0003] Japanese Patent Application Laid-Open No. 7-24288 discloses a closed kneader configured to control the lifting and lowering operation of a weight by air pressure. The lifting and lowering operation of the weight is performed by operating a cylinder by air pressure. When the weight is lifted, while detecting the position of the weight, when it is detected that the weight has risen to a preset position, the shut-off valve is operated to stop the lifting operation of the weight.

[0004] In addition, closed kneaders are also disclosed in Japanese Patent Application Laid-Open No. 10-211616 and Japanese Patent Application Laid-Open No. 9-206581.

[0005] In recent years, the materials and additives of kneaded materials have become diversified, and there has been an increasing need to knead kneaded materials containing a large amount of evaporation components (moisture) compared to the conventional case. When kneading a kneaded material containing a large amount of moisture or the like, since the moisture or the like vaporizes as the temperature rises during kneading, the internal pressure of the kneading chamber may rapidly increase. In such a state, if the control to raise the weight is performed, there is a risk that the weight will rapidly rise under the influence of the internal pressure. In that case, there is a risk that the weight cannot be controlled to an appropriate position.

[0006] Further, when the position control of the weight is performed by air pressure, the pressing force that can be applied is lower than that by hydraulic pressure. Therefore, the position control by air pressure is not suitable for kneading materials in which the internal pressure of the kneading chamber increases due to the generation of evaporation components.

[0007] The objective of this invention is to suppress unintended upward movement of the weight when the weight is increased while the pressure inside the kneading chamber is high.

[0008] In one aspect of the present invention, a closed-type kneader includes a kneading chamber having a kneading chamber; a material input section located above the kneading chamber and for passing a material to be kneaded, made of polymer material, into the kneading chamber; a pair of kneading rotors arranged in the kneading chamber so as to be rotatable parallel to each other and configured to knead the material to be kneaded; a weight positioned in the material input section so as to be able to press the material to be kneaded in the kneading chamber from above; a hydraulic circuit having a hydraulic cylinder connected to the weight; a pressing operation that supplies hydraulic fluid to the hydraulic cylinder so as to press the material to be kneaded by the weight; and a rapid rise suppression operation that restricts the movement of the hydraulic cylinder so as to suppress the upward movement speed of the weight when the pressing operation is released.

[0009] This diagram schematically shows the overall configuration of a closed-type kneader according to the first embodiment. This diagram schematically shows the overall configuration of a closed-type kneader according to the second embodiment. This diagram schematically shows the overall configuration of a closed-type kneader according to the third embodiment.

[0010] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[0011] (First Embodiment) As shown in Figure 1, the sealed kneader 50 according to this embodiment is a device for kneading materials such as rubber and resin, and comprises a kneader body 51, a hydraulic circuit 52 connected to the kneader body 51, and a controller 20 for controlling the hydraulic circuit 52. The kneader body 51 comprises a kneading chamber 1 having a kneading chamber 1a, a material input section 4 located above the kneading chamber 1, a weight 6 placed inside the material input section 4, and a pair of kneading rotors 2 placed inside the kneading chamber 1a. The pair of kneading rotors 2 are arranged to rotate parallel to each other inside the kneading chamber 1a. When the pair of kneading rotors 2 are driven, the material to be kneaded inside the kneading chamber 1a is kneaded.

[0012] The top of the mixing chamber 1a is open. The weight 6 is provided to be able to move up and down within the material input section 4, and can be lowered to a position (lower position) where it enters the upper opening of the mixing chamber 1a.

[0013] A hopper 5 is provided in the material input section 4. When the weight 6 is in a position above the hopper 5 (upper position), the materials to be kneaded are introduced into the internal space of the material input section 4 through the hopper 5.

[0014] The weight 6 is connected to a hydraulic cylinder 7 provided in the hydraulic circuit 52. The hydraulic cylinder 7 has a cylinder body 7a and a piston 7b slidably disposed within the cylinder body 7a. The piston 7b is connected to the weight 6 via a connecting member 15. Therefore, the weight 6 moves up and down as the piston 7b slides within the cylinder body 7a.

[0015] The cylinder body 7a is equipped with a position detector 8 for detecting the vertical position of the weight 6. The position detector 8 outputs a signal indicating the detected position. This signal is input to the controller 20.

[0016] Within the cylinder body 7a, a first hydraulic chamber 7c is formed on one side relative to the piston 7b, and a second hydraulic chamber 7d is formed on the other side relative to the piston 7b. The first hydraulic chamber 7c functions as a pressure chamber that generates hydraulic pressure to push the weight 6 into the kneading chamber 1a. Therefore, when the weight 6 is raised, the first hydraulic chamber 7c becomes a hydraulic chamber through which hydraulic fluid flows out. The second hydraulic chamber 7d functions as a pressure chamber that generates hydraulic pressure to raise the weight 6 out of the kneading chamber 1a. In other words, the second hydraulic chamber 7d is a hydraulic chamber through which hydraulic fluid flows in when the weight 6 is raised.

[0017] The hydraulic circuit 52 includes a hydraulic servo valve 13. The hydraulic servo valve 13 is a switching valve configured to switch between raising, lowering, and stopping the weight 6. The hydraulic servo valve 13 also has four ports (port A, port B, port P, and port T). The hydraulic servo valve 13 has a pilot port 13a that receives signals from the controller 20 and adjusts the direction and amount of hydraulic fluid supply based on the received signals.

[0018] The hydraulic circuit 52 includes a supply line 52a connected to the P port of the hydraulic servo valve 13, a discharge line 52b connected to the T port of the hydraulic servo valve 13, a first hydraulic line 52c connected to the B port of the hydraulic servo valve 13, and a second hydraulic line 52d connected to the A port of the hydraulic servo valve 13.

[0019] The supply pipeline 52a is equipped with a pump 10 that supplies hydraulic fluid from the tank 19 to the hydraulic servo valve 13, and a check valve 11. The pump 10 is driven by a hydraulic motor 9.

[0020] The discharge pipe 52b is a pipe that returns the hydraulic fluid to the tank 19 from the T port of the hydraulic servo valve 13. A check valve 12 is provided in the discharge pipe 52b.

[0021] The first hydraulic pipeline 52c connects the first hydraulic chamber 7c and the B port of the hydraulic servo valve 13. A check valve 24 is provided in the first hydraulic pipeline 52c. The check valve 24 allows the flow of hydraulic fluid from the hydraulic servo valve 13 toward the first hydraulic chamber 7c, while blocking the flow of hydraulic fluid in the reverse direction.

[0022] The second hydraulic pipeline 52d connects the second hydraulic chamber 7d and port A of the hydraulic servo valve 13. Pressure gauges 3 are installed in both the first hydraulic pipeline 52c and the second hydraulic pipeline 52d.

[0023] The hydraulic servo valve 13 is a switching valve that can adjust the direction and amount of hydraulic fluid supply, and is configured to switch between a pressed state, a retracted state, and a stopped state. The hydraulic servo valve 13 switches between these states based on a signal from the controller 20 to the pilot port 13a.

[0024] In the compressed state, port P is connected to port B and port A is connected to port T. As a result, hydraulic fluid from supply line 52a is supplied to the first hydraulic chamber 7c through the first hydraulic line 52c, and hydraulic fluid from the second hydraulic chamber 7d flows out into the second hydraulic line 52d. This positions the piston 7b in the lower position.

[0025] In the retracted state, port P is connected to port A and port B is connected to port T. As a result, hydraulic fluid from supply line 52a is supplied to the second hydraulic chamber 7d through the second hydraulic line 52d, and hydraulic fluid from the first hydraulic chamber 7c flows out into the first hydraulic line 52c. This causes piston 7b to rise from its lower position.

[0026] In the stopped state, the flow of hydraulic fluid between ports A and B, and between ports P and T, is stopped.

[0027] The hydraulic circuit 52 further includes a connecting pipe 52e, a branching pipe 52f, a bypass pipe 52g, and a pilot pipe 26.

[0028] The connecting pipeline 52e is a pipeline that connects the first hydraulic pipeline 52c and the supply pipeline 52a. The connecting pipeline 52e has one end (also referred to as the connecting part S) that is connected to the portion between the check valve 24 and the first hydraulic chamber 7c in the first hydraulic pipeline 52c, and the other end that is connected between the pump 10 (or check valve 11) and the hydraulic servo valve 13 in the supply pipeline 52a. The other end of the connecting pipeline 52e may be connected to the tank 19.

[0029] The connecting pipeline 52e is equipped with a flow limiting valve 16 and a check valve 25. The flow limiting valve 16 is configured to limit the flow rate of hydraulic fluid flowing through the connecting pipeline 52e to below a predetermined level. The check valve 25 allows the flow of hydraulic fluid from the first hydraulic pipeline 52c into the connecting pipeline 52e, while blocking the flow of hydraulic fluid in the reverse direction. In other words, the check valve 25 allows the flow of hydraulic fluid from the first hydraulic chamber 7c back to the hydraulic servo valve 13, while blocking the flow of hydraulic fluid in the reverse direction.

[0030] The section of the first hydraulic pipeline 52c from the first hydraulic chamber 7c to the connection point S of the connecting pipeline 52e and the connecting pipeline 52e constitute a return pipeline 52h that returns the hydraulic fluid that flows out of the first hydraulic chamber 7c when the weight 6 is raised back to the hydraulic servo valve 13.

[0031] The branch pipeline 52f is connected to the portion of the first hydraulic pipeline 52c between the first hydraulic chamber 7c and the connection point S of the connecting pipeline 52e. The branch pipeline 52f is also connected to the tank 19. The branch pipeline 52f is provided with a shut-off valve 18 and a relief valve 22.

[0032] The shut-off valve 18 is configured to open the branch pipeline 52f when it receives a signal from the controller 20, and to shut off the branch pipeline 52f when it stops receiving signals. In other words, during normal operation, the shut-off valve 18 continuously receives signals from the controller 20, so the branch pipeline 52f remains open.

[0033] The relief valve 22 is configured to release pressure when the pressure in the branch pipe 52f exceeds a predetermined value. The relief valve 22 may also be a proportional relief valve whose operating pressure setting can be changed by a command from the controller 20.

[0034] The bypass pipeline 52g is connected to the branch pipeline 52f so as to bypass the shut-off valve 18, and is also connected to the tank 19. A relief valve 27 is provided in the bypass pipeline 52g. The relief valve 27 is configured to release pressure when the pressure in the first hydraulic pipeline 52c (or bypass pipeline 52g) exceeds a predetermined value while the shut-off valve 18 is shut off. The relief valve 27 may be a proportional relief valve whose operating pressure setting can be changed by a command from the controller 20.

[0035] The pilot pipeline 26 connects the supply pipeline 52a and the pilot port 13a of the hydraulic servo valve 13. A shut-off valve 23 is provided in the pilot pipeline 26. The shut-off valve 23 is configured to open the pilot pipeline 26 when it receives a signal from the controller 20, and to shut off the pilot pipeline 26 when it stops receiving signals. When the pilot pipeline 26 is shut off, the hydraulic supply to the pilot port 13a is stopped, and the hydraulic servo valve 13 returns to the stopped state. During normal operation, the shut-off valve 23 continuously receives signals from the controller 20, so the pilot pipeline 26 remains open.

[0036] The controller 20 consists of a microcomputer equipped with a CPU that performs calculations, a ROM that stores processing programs and data, and a RAM that temporarily stores data. The controller 20 controls the hydraulic servo valve 13 so that pressing and rapid rise suppression operations are performed by executing processing programs. In other words, the controller 20 includes a pressing operation execution unit and a rapid rise suppression operation execution unit as its functions. The pressing operation execution unit performs control operations for executing the pressing operation, and the rapid rise suppression operation execution unit performs control operations for executing the rapid rise suppression operation.

[0037] During the pressing operation, the weight 6 is positioned in a lower position where it enters the upper opening of the kneading chamber 1a, and hydraulic fluid is supplied to the first hydraulic chamber 7c of the hydraulic cylinder 7 so that the material to be kneaded in the kneading chamber 1a is pressed by the weight 6. In this case, the controller 20 drives the hydraulic motor 9 to operate the pump 10 and switches the hydraulic servo valve 13 to the pressed state.

[0038] The rapid upward suppression operation is performed when the pressing operation is released. The pressing operation is released when, for example, the controller 20 receives a command to raise the weight 6 from the lower position, when there is a power loss, when the controller 20 receives an emergency stop command, or when the controller 20 receives a fault signal for hydraulic equipment such as a hydraulic motor or hydraulic piping.

[0039] When the controller 20 receives a command to raise the weight 6 from its lower position, the controller 20 switches the hydraulic servo valve 13 to a retracted state. At this time, the controller 20 controls the hydraulic servo valve 13 based on the position signal detected by the position detector 8. That is, the controller 20 calculates the movement speed of the weight 6 from the time change in the position of the weight 6 detected by the position detector 8, and controls the hydraulic servo valve 13 so that the upward movement speed of the weight 6 becomes approximately constant. As a result, even if the weight 6 is raised while the pressure in the mixing chamber 1a is high, a sudden rise in the weight 6 can be suppressed.

[0040] Furthermore, when the hydraulic servo valve 13 is switched to the retracted state, the hydraulic fluid from the supply line 52a is supplied to the second hydraulic chamber 7d through the second hydraulic line 52d, and the hydraulic fluid from the first hydraulic chamber 7c flows out into the first hydraulic line 52c. Since the first hydraulic line 52c is provided with a check valve 24, the hydraulic fluid from the first hydraulic line 52c flows into the connecting line 52e. Therefore, the flow rate limiting valve 16 limits the flow rate of the hydraulic fluid flowing through the first hydraulic line 52c to below a predetermined level. This hydraulic fluid flows into the supply line 52a. In other words, in addition to the hydraulic servo valve 13 being controlled so that the upward movement speed of the weight 6 is approximately constant, the flow rate of the hydraulic fluid is limited by the flow rate limiting valve 16.

[0041] Furthermore, when power is lost, the transmission of signals from the controller 20 to the shut-off valves 18 and 23 is stopped. Therefore, when power is lost, the branch pipeline 52f is shut off by the shut-off valve 18, and the pilot pipeline 26 is shut off by the shut-off valve 23. The shut-off of the pilot pipeline 26 causes the hydraulic servo valve 13 to return to a stopped state. As a result, the hydraulic fluid between the first hydraulic chamber 7c and the tank 19, and between the first hydraulic chamber 7c and the P port of the hydraulic servo valve 13, is held in place without flowing. Consequently, if power is lost while the weight 6 is rising, the rise of the weight 6 will stop. In other words, the rapid rise of the weight 6 is further suppressed.

[0042] Also, even when power is lost while the weight 6 is held in the lower position, for example, the hydraulic oil between the first hydraulic chamber 7c and the tank 19 and between the first hydraulic chamber 7c and the P port of the hydraulic servo valve 13 is held as it is. Therefore, power loss prevents the weight 6 from rising rapidly under the internal pressure of the kneading chamber 1a.

[0043] Also, when the controller 20 receives an emergency stop command, the transmission of signals from the controller 20 to the shut-off valve 18 and the shut-off valve 23 is stopped. Therefore, also in this case, the branch pipe 52f is blocked by the shut-off valve 18 and the pilot pipe 26 is blocked by the shut-off valve 23. Blocking of the pilot pipe 26 causes the hydraulic servo valve 13 to return to the stopped state. For this reason, the hydraulic oil between the first hydraulic chamber 7c and the tank 19 and between the first hydraulic chamber 7c and the P port of the hydraulic servo valve 13 is held. Thereby, when the controller 20 receives an emergency stop command while the weight 6 is rising, the rising of the weight 6 stops. In other words, a rapid rise of the weight 6 is suppressed.

[0044] As described above, in the closed kneader 50 according to the present embodiment, the controller 20 controls the hydraulic circuit 52 so that a pressing operation is performed when kneading the kneaded material. In this pressing operation, hydraulic oil is supplied to the hydraulic cylinder 7 so that the kneaded material is pressed by the weight 6, and a pressing force is applied to the weight 6 by the hydraulic cylinder 7. Further, the controller 20 controls the hydraulic circuit 52 so that a rapid rise suppression operation is performed when the pressing operation is released. In this rapid rise suppression operation, the operation of the hydraulic cylinder 7 is regulated so that the upward movement speed of the weight 6 is suppressed. Therefore, even when the pressing operation is released in a state where evaporation components such as moisture are generated from the kneaded material and the pressure in the kneading chamber 1a is high, it is possible to prevent the weight 6 from rising rapidly under the high pressure in the kneading chamber 1a. That is, it is possible to suppress the occurrence of an unintended upward movement of the weight 6.

[0045] Furthermore, in this embodiment, during the rapid rise suppression operation, the hydraulic servo valve 13 is controlled so that the movement speed of the weight 6 remains approximately constant. Therefore, even if the pressing operation is released when the pressure inside the kneading chamber 1a is high due to the generation of evaporative components such as water from the material being kneaded, a rapid rise of the weight 6 can be prevented. In addition, because the operation is controlled by the hydraulic servo valve 13, the weight 6 can be operated smoothly.

[0046] Furthermore, in this embodiment, during the rapid rise suppression operation, the flow rate of the hydraulic fluid flowing out of the first hydraulic chamber 7c of the hydraulic cylinder 7 is limited to a predetermined level by the flow rate limiting valve 16. Therefore, even if the pressing operation is released while the pressure inside the kneading chamber 1a is high due to evaporation components such as water generated from the material being kneaded, it is possible to prevent the weight 6 from rising rapidly due to the high pressure inside the kneading chamber 1a. In other words, in addition to the hydraulic servo valve 13 being controlled so that the upward movement speed of the weight 6 is approximately constant, the flow rate of the hydraulic fluid is limited by the flow rate limiting valve 16. Therefore, the rapid rise of the weight 6 can be suppressed more reliably. Moreover, because the flow rate is limited by a mechanical mechanism such as an internal throttling, the rapid rise of the weight 6 can be suppressed more reliably.

[0047] Furthermore, in this embodiment, during an emergency stop or other rapid rise suppression operation, the shut-off valve 18 blocks the flow of hydraulic fluid in the branch pipeline 52f, and the hydraulic servo valve 13 controls the flow of hydraulic fluid in the first hydraulic pipeline 52c. As a result, the rapid rise of the weight 6 is stopped, thus preventing unintended upward movement of the weight 6. In addition, since the shut-off valve 18 is provided in the branch pipeline 52f, there is no need to install any extra equipment in the first hydraulic pipeline 52c. Furthermore, when mixing materials under normal circumstances, it is also possible to avoid using the hydraulic equipment beyond the branch pipeline 52f.

[0048] Further, in the present embodiment, a bypass line 52g that bypasses the shut-off valve 18 is provided in the branch line 52f where the relief valve 22 is provided, and a relief valve 27 is provided in this bypass line 52g. Therefore, even when the shut-off valve 18 functions and the relief valve 22 is blocked from the first hydraulic line 52c (or the return line 52h), the relief valve 27 can prevent the pressure in the first hydraulic line 52c (or the return line 52h) from rising above the expected pressure.

[0049] Further, in the present embodiment, in the rapid rise suppression operation, when the shut-off valve 23 operates, the hydraulic servo valve 13 returns to the stopped state. In this case, in addition to suppressing the rapid rise by the constant speed control upward of the weight 6, the supply stop of the hydraulic oil from the hydraulic servo valve 13 can surely prevent the rapid rise of the weight 6. Also, the hydraulic oil leakage in the pilot circuit portion of the hydraulic servo valve 13 can be prevented.

[0050] Further, in the present embodiment, even when the rapid rise of the weight 6 cannot be prevented only by controlling the rising speed of the weight 6 to be substantially constant by the hydraulic servo valve 13, it is possible to limit the rising speed of the weight 6 by the flow rate limiting valve 16. Furthermore, since the shut-off valve 18 and the shut-off valve 23 also prevent the rapid rise of the weight 6, the rapid rise of the weight 6 can be more surely prevented.

[0051] Note that in the present embodiment, since the rapid rise of the weight 6 by the hydraulic servo valve 13 is suppressed and the flow rate limiting valve 16 is also provided, the shut-off valve 23 in the pilot line 26 can be omitted.

[0052] Further, in the present embodiment, since the rapid rise of the weight 6 by the hydraulic servo valve 13 is suppressed and the flow rate limiting valve 16 is also provided, the shut-off valve 18 arranged in the branch line 52f may be omitted. In this case, the bypass line 52g having the relief valve 27 is also omitted.

[0053] Furthermore, in this embodiment, the movement speed of the piston 7b (weight 6) is controlled by controlling the hydraulic servo valve 13 based on the detected position of the position detector 8, making it possible to omit the flow limiting valve 16. However, the flow limiting valve 16 can more reliably suppress a sudden rise.

[0054] Furthermore, in this embodiment, when raising the weight 6, the hydraulic servo valve 13 is controlled so that the movement speed of the weight 6 remains substantially constant based on the position detected by the position detector 8, but this control may be omitted. In this case, the upward movement speed of the weight 6 is suppressed by the flow limiting valve 16.

[0055] Furthermore, in this embodiment, the pressure inside the first hydraulic pipeline 52c can be detected by a pressure gauge 3 provided in the first hydraulic pipeline 52c. Therefore, instead of always performing position control by the position detector 8 when raising the weight 6, it is also possible to perform constant speed control of the weight 6 based on the position detected by the position detector 8 only when the pressure detected by the pressure gauge 3 in the first hydraulic pipeline 52c exceeds a predetermined pressure. In this case, when the pressure detected by the pressure gauge 3 in the first hydraulic pipeline 52c is below the predetermined pressure, the weight 6 can be raised without referring to the value detected by the position detector 8.

[0056] (Second Embodiment) As shown in Figure 2, the closed-type kneader 50 according to the second embodiment is equipped with a flow rate limiting mechanism 29 located in the connecting pipeline 52e, while the shut-off valve 23 in the pilot pipeline 26 is omitted. Here, the same reference numerals are used for the same components as in the first embodiment, and their detailed descriptions are omitted.

[0057] The flow limiting mechanism 29 includes a flow limiting valve 16 and a shut-off valve 30. The flow limiting mechanism 29 is configured to switch the flow state of the hydraulic fluid in the connecting pipeline 52e between a flow limiting state in which the flow limiting valve 16 is activated and a flow shut-off state in which the shut-off valve 30 is activated. The flow limiting mechanism 29 can be switched between the flow limiting state and the flow shut-off state by a command from the controller 20.

[0058] When the controller 20 receives a command to raise the weight 6 from its lower position, the controller 20 switches the hydraulic servo valve 13 to a retracted state and switches the flow rate limiting mechanism 29 to a flow rate limiting state. As a result, the flow rate of the hydraulic fluid flowing out of the first hydraulic chamber 7c and through the return pipe 52h is limited by the flow rate limiting mechanism 29. Therefore, even if the pressurization inside the mixing chamber 1a increases, a rapid rise in the weight 6 can be suppressed.

[0059] When power is lost or the controller 20 receives an emergency stop command, the controller 20 switches the hydraulic servo valve 13 to the stopped state and switches the flow limiting mechanism 29 to the flow-blocking state. At the same time, the shut-off valve 18 of the branch pipeline 52f is also shut off. As a result, the outflow of hydraulic fluid from the first hydraulic chamber 7c is blocked, and the piston 7b of the hydraulic cylinder 7 stops. This prevents a rapid rise in the weight 6 even if the pressure inside the mixing chamber 1a has increased.

[0060] In this embodiment, the branch pipeline 52f and the bypass pipeline 52g can be omitted.

[0061] Furthermore, in this embodiment, when raising the weight 6, the controller 20 controls the hydraulic servo valve 13 so that the movement speed of the weight 6 remains substantially constant based on the position detected by the position detector 8. However, this control can be omitted.

[0062] Furthermore, in this embodiment, it is not always necessary to perform position control using the position detector 8 when raising the weight 6. That is, the controller 20 may perform constant speed control of the weight 6 based on the position detected by the position detector 8 only when the pressure detected by the pressure gauge 3 of the first hydraulic pipeline 52c exceeds a predetermined pressure.

[0063] The other configurations, functions, and effects will not be described here, but the description of the first embodiment can be applied to the second embodiment.

[0064] (Third Embodiment) As shown in Figure 3, in the third embodiment, a shut-off valve 28 is provided in the first hydraulic pipeline 52c instead of the shut-off valve 23 located in the pilot pipeline 26. Here, the same reference numerals are used for components that are the same as in the first and second embodiments, and their detailed descriptions are omitted.

[0065] The shut-off valve 28 is located between the connection point S of the first hydraulic chamber 7c and the connecting pipeline 52e in the first hydraulic pipeline 52c. The shut-off valve 28 is configured to open the first hydraulic pipeline 52c when it receives a signal from the controller 20, and to shut off the first hydraulic pipeline 52c when signal reception stops. That is, during normal operation, the shut-off valve 28 continuously receives signals from the controller 20, so the first hydraulic pipeline 52c remains open. On the other hand, when power is lost, the transmission of signals from the controller 20 to the shut-off valve 28 stops, so the shut-off valve 28 shuts off the first hydraulic pipeline 52c. At this time, the shut-off valve 18 of the branch pipeline 52f is also shut off.

[0066] Furthermore, when the controller 20 receives an emergency stop command, the transmission of signals from the controller 20 to the shut-off valves 18 and 28 is stopped. Therefore, in this case as well, the branch pipeline 52f is shut off by the shut-off valve 18, and the first hydraulic pipeline 52c is shut off by the shut-off valve 28.

[0067] Therefore, in this embodiment, during an emergency stop or other rapid rise suppression operation, the shut-off valve 18 blocks the flow of hydraulic fluid in the branch pipeline 52f, and the shut-off valve 28 stops the flow of hydraulic fluid in the first hydraulic pipeline 52c. As a result, the rapid rise of the weight 6 is stopped, and unintended upward movement of the weight 6 can be suppressed.

[0068] In this embodiment, the branch pipeline 52f and the bypass pipeline 52g can be omitted. Also, in this embodiment, the flow limiting valve 16 can be omitted. Furthermore, in this embodiment, when raising the weight 6, the controller 20 controls the hydraulic servo valve 13 so that the movement speed of the weight 6 becomes substantially constant based on the detected position of the position detector 8. However, this control can be omitted. Also, in this embodiment, it is not always necessary to perform position control by the position detector 8 when raising the weight 6. That is, constant speed control of the weight 6 based on the detected position of the position detector 8 may be performed only when the pressure detected by the pressure gauge 3 of the first hydraulic pipeline 52c exceeds a predetermined pressure.

[0069] The other configurations, functions, and effects will not be described here, but the description of the first embodiment can be applied to the second embodiment.

[0070] (Other Embodiments) It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The present invention is not limited to the embodiments described above, and various modifications and improvements are possible without departing from the spirit of the invention.

[0071] Here, we will give an overview of the embodiment described above.

[0072] The enclosed kneader in the above embodiment includes a kneading chamber having a kneading chamber; a material input unit located above the kneading chamber and for passing a material to be kneaded, made of polymer material, into the kneading chamber; a pair of kneading rotors arranged in the kneading chamber so as to be rotatable parallel to each other and configured to knead the material to be kneaded; a weight positioned in the material input unit so as to be able to press the material to be kneaded in the kneading chamber from above; a hydraulic circuit having a hydraulic cylinder connected to the weight; a pressing operation that supplies hydraulic fluid to the hydraulic cylinder so as to press the material to be kneaded by the weight; and a rapid rise suppression operation that restricts the movement of the hydraulic cylinder so as to suppress the upward movement speed of the weight when the pressing operation is released.

[0073] In the aforementioned closed-type kneader, the controller controls the hydraulic circuit so that a pressing action is performed when the material to be kneaded is being mixed. In this pressing action, hydraulic fluid is supplied to the hydraulic cylinder so that the material to be kneaded is pressed by the weight, and the hydraulic cylinder applies a pressing force to the weight. The controller also controls the hydraulic circuit so that a rapid rise suppression action is performed when the pressing action is released. In this rapid rise suppression action, the operation of the hydraulic cylinder is restricted so that the upward movement speed of the weight is suppressed. Therefore, even if the pressing action is released while the pressure inside the kneading chamber is high due to the generation of evaporative components such as water from the material to be kneaded, it is possible to prevent the weight from rising rapidly due to the high pressure inside the kneading chamber. In other words, it is possible to suppress unintended upward movement of the weight.

[0074] The enclosed kneader may further include a position detector for detecting the vertical position of the weight. The hydraulic circuit may have a hydraulic servo valve capable of adjusting the direction and amount of hydraulic fluid supplied to the hydraulic cylinder. In this case, the controller may be configured to calculate the movement speed of the weight from the time change in the position of the weight detected by the position detector during the rapid rise suppression operation, and to control the hydraulic servo valve so that the upward movement speed of the weight remains substantially constant.

[0075] In this embodiment, during the rapid rise suppression operation, the hydraulic servo valve is controlled so that the weight's movement speed remains approximately constant. Therefore, even if the pressing operation is released while the pressure inside the kneading chamber is high due to the generation of evaporative components such as water from the material being kneaded, a rapid rise in the weight can be prevented. Furthermore, because the operation is controlled by the hydraulic servo valve, the weight can be moved smoothly.

[0076] The hydraulic cylinder may have a first hydraulic chamber into which hydraulic fluid is introduced when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid is introduced when the weight is raised. The hydraulic circuit may have a hydraulic servo valve configured to switch the direction of supply of hydraulic fluid to the first hydraulic chamber or the second hydraulic chamber, and a flow limiting valve that limits the flow rate of hydraulic fluid flowing out of the first hydraulic chamber to below a predetermined level. In this case, the controller may be configured to control the hydraulic servo valve so that hydraulic fluid flows to the flow limiting valve during the rapid rise suppression operation.

[0077] In this embodiment, during the rapid rise suppression operation, the flow rate of the hydraulic fluid flowing out of the first hydraulic chamber of the hydraulic cylinder is limited to a predetermined level by a flow limiting valve. Therefore, even if the pressing operation is released while the pressure inside the kneading chamber is high due to evaporation components such as water generated from the material being kneaded, it is possible to prevent the weight from rising rapidly due to the high pressure inside the kneading chamber. Moreover, since the flow rate is limited by a mechanical mechanism called an internal throttling, the rapid rise of the weight can be suppressed more reliably even when position control by a servo mechanism is not performed.

[0078] The hydraulic cylinder may have a first hydraulic chamber through which hydraulic fluid is introduced when the weight is lowered, and a second hydraulic chamber through which hydraulic fluid is introduced when the weight is raised. The hydraulic circuit may have a return line through which the hydraulic fluid that has flowed out of the first hydraulic chamber flows, and a flow rate limiting mechanism provided in the return line. The flow rate limiting mechanism may include a flow rate limiting valve that limits the flow rate of hydraulic fluid flowing out of the first hydraulic chamber to below a predetermined level, and a shut-off valve that blocks the outflow of hydraulic fluid from the first hydraulic chamber. In this case, the controller may control the flow rate limiting mechanism so that the flow rate limiting valve of the flow rate limiting mechanism functions when the pressing operation is released by a command to raise the weight, and the shut-off valve of the flow rate limiting mechanism functions when the pressing operation is released by a power loss or emergency stop command.

[0079] In this embodiment, the flow limiting mechanism functions as a flow limiting valve when the pressing action is released by a command to raise the weight, and also functions as a shut-off valve when power is lost or an emergency stop command is received. Therefore, in either case when the pressing action is released, the upward movement speed of the weight is suppressed. As a result, even if the pressing action is released while the pressure inside the kneading chamber is high due to evaporation of water and other components from the material being kneaded, it is possible to prevent the weight from rising rapidly due to the high pressure inside the kneading chamber.

[0080] The hydraulic cylinder may have a first hydraulic chamber through which hydraulic fluid is introduced when the weight is lowered, and a second hydraulic chamber through which hydraulic fluid is introduced when the weight is raised. The hydraulic circuit may have a return line through which the hydraulic fluid that has flowed out of the first hydraulic chamber flows, and a shut-off valve provided in the return line. In this case, the controller may control the shut-off valve so as to shut off the flow of hydraulic fluid in the return line during the rapid rise suppression operation.

[0081] In this embodiment, during the rapid rise suppression operation, the flow of hydraulic fluid in the return pipeline is shut off by the shut-off valve. This stops the rapid rise of the weight, thereby preventing unintended upward movement of the weight. Moreover, since the shut-off valve can be operated instantaneously in a short time, the rapid rise of the weight can be prevented more reliably.

[0082] The hydraulic cylinder may have a first hydraulic chamber into which hydraulic fluid is introduced when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid is introduced when the weight is raised. The hydraulic circuit may have a hydraulic servo valve configured to switch the direction of supply of hydraulic fluid to the first hydraulic chamber or the second hydraulic chamber, a return line to return the hydraulic fluid that has flowed out of the first hydraulic chamber to the hydraulic servo valve, and a shut-off valve provided in a branch line branching off from the return line. In this case, the controller may control the hydraulic servo valve so as to stop the flow of hydraulic fluid in the return line during the rapid rise suppression operation, and may also control the shut-off valve so as to shut off the flow of hydraulic fluid in the branch line.

[0083] In this embodiment, during the rapid rise suppression operation, the flow of hydraulic fluid in the branch pipeline is shut off by a shut-off valve, and the flow of hydraulic fluid in the first hydraulic pipeline is stopped by the control of a hydraulic servo valve. As a result, the rapid rise of the weight is stopped, thus preventing unintended upward movement of the weight. Furthermore, since the shut-off valve is installed in the branch pipeline, there is no need to install extra equipment in the first hydraulic pipeline. In addition, when mixing ordinary materials, it is possible to avoid using the hydraulic equipment beyond the branch pipeline.

[0084] The sealed kneader may further include a relief valve provided in a bypass pipeline connected to the branch pipeline so as to bypass the shut-off valve.

[0085] In this embodiment, when the branch pipeline is shut off by the shut-off valve, it is possible to prevent the pressure in the return pipeline from rising to a pressure higher than expected. Furthermore, in cases such as when the weight of the material being mixed is pushed up, it becomes possible to improve pressure accuracy or prevent damage to the return pipeline.

[0086] The hydraulic circuit may further include a shut-off valve located in the pilot line of the hydraulic servo valve. In this case, the controller may be configured to control the shut-off valve so that the flow of hydraulic fluid in the pilot line is shut off during the rapid rise suppression operation. The hydraulic servo valve may also be configured to switch to a stopped state in which the supply of hydraulic fluid from the hydraulic servo valve is stopped when the hydraulic supply to the pilot line is stopped.

[0087] In this embodiment, the shut-off valve in the pilot pipeline is activated during the rapid rise suppression operation. Therefore, in addition to suppressing the rapid rise by the flow limiting valve, the rapid rise of the weight can be reliably prevented by stopping the supply of hydraulic fluid from the hydraulic servo valve. Furthermore, hydraulic fluid leakage in the pilot circuit portion of the hydraulic servo valve can also be prevented.

[0088] The controller may be configured to activate the shut-off valve when the pressing action is released due to a power loss. In this configuration, a sudden rise in the weight can be prevented even in the abnormal situation of a power loss.

[0089] The controller may be configured to activate the shut-off valve when the pressing action is released upon receiving an emergency stop command. In this embodiment, a sudden rise in the weight can be prevented during an emergency stop.

[0090] The sealed kneader may further include a position detector for detecting the vertical position of the weight. In this case, the hydraulic cylinder may have a first hydraulic chamber into which hydraulic fluid flows when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid flows when the weight is raised. The hydraulic circuit may also include a hydraulic servo valve capable of adjusting the direction and amount of hydraulic fluid supplied to the first or second hydraulic chamber, a flow limiting valve that limits the flow rate of hydraulic fluid in the return pipeline through which the hydraulic fluid that has flowed out of the first hydraulic chamber flows to a predetermined level or less, and a shut-off valve provided in the return pipeline. In this case, the controller may be configured to calculate the movement speed of the weight from the time change of the position of the weight detected by the position detector during the rapid rise suppression operation, and to control the hydraulic servo valve so that the upward movement speed of the weight becomes substantially constant and hydraulic fluid flows in the return pipeline, and to control the shut-off valve so that the flow of hydraulic fluid in the return pipeline is shut off.

[0091] In this embodiment, when the pressing action is released, a sudden rise in the weight can be prevented more reliably. That is, even if a sudden rise in the weight cannot be prevented by simply controlling the weight's rising speed to a nearly constant level with a hydraulic servo valve, the flow limiting valve can be used to limit the weight's rising speed. Furthermore, a shut-off valve is also used to prevent a sudden rise in the weight, thus more reliably preventing a sudden rise in the weight.

[0092] The enclosed kneader may further include a position detector for detecting the vertical position of the weight. In this case, the hydraulic cylinder may have a first hydraulic chamber into which hydraulic fluid flows when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid flows when the weight is raised. The hydraulic circuit may also include a hydraulic servo valve configured to switch the direction of hydraulic fluid supply to the first hydraulic chamber or the second hydraulic chamber, a return line for returning hydraulic fluid that has flowed out of the first hydraulic chamber to the hydraulic servo valve, a flow limiting valve for limiting the flow rate of hydraulic fluid flowing through the return line to a predetermined level or lower, and a shut-off valve provided in a branch line branching off from the return line. In this case, the controller may be configured to control the hydraulic servo valve so that, in the rapid rise suppression operation, hydraulic fluid flows out of the first hydraulic chamber, the movement speed of the weight is calculated from the time change of the position of the weight detected by the position detector, the upward movement speed of the weight becomes substantially constant, and hydraulic fluid flows into the return pipe, and to control the shut-off valve so that the flow of hydraulic fluid in the branch pipe is blocked.

[0093] In this embodiment, when the pressing action is released, a sudden rise in the weight can be prevented more reliably. That is, even if a sudden rise in the weight cannot be prevented by simply controlling the weight's rising speed to a nearly constant level with a hydraulic servo valve, the flow limiting valve can be used to limit the weight's rising speed. Furthermore, a shut-off valve is also used to prevent a sudden rise in the weight, thus more reliably preventing a sudden rise in the weight.

[0094] The enclosed kneader may further include a position detector for detecting the vertical position of the weight. In this case, the hydraulic cylinder may have a first hydraulic chamber into which hydraulic fluid flows when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid flows when the weight is raised. The hydraulic circuit may also include a hydraulic servo valve configured to switch the direction of hydraulic fluid supply to the first hydraulic chamber or the second hydraulic chamber, a return line for returning hydraulic fluid that has flowed out of the first hydraulic chamber to the hydraulic servo valve, a flow limiting valve for limiting the flow rate of hydraulic fluid flowing through the return line to a predetermined level or less, and a shut-off valve located in the pilot line of the hydraulic servo valve. In this case, the controller may be configured to control the hydraulic servo valve so that, in the rapid rise suppression operation, hydraulic fluid flows out of the first hydraulic chamber, the movement speed of the weight is calculated from the time change of the position of the weight detected by the position detector, the upward movement speed of the weight becomes substantially constant, and hydraulic fluid flows through the return line, and to control the shut-off valve so that the flow of hydraulic fluid in the pilot line is blocked.

[0095] In this embodiment, when the pressing action is released, a sudden rise in the weight can be prevented more reliably. That is, even if a sudden rise in the weight cannot be prevented by simply controlling the weight's rising speed to a nearly constant level with a hydraulic servo valve, the flow limiting valve can be used to limit the weight's rising speed. Furthermore, a shut-off valve is also used to prevent a sudden rise in the weight, thus more reliably preventing a sudden rise in the weight.

[0096] As explained above, it is possible to suppress unintended upward movement of the weight when the weight is increased while the pressure inside the mixing chamber is high.

[0097] This application is based on Provisional Application No. 63 / 707451, filed with the United States Patent and Trademark Office on 15 October 2024, the contents of which are incorporated herein by reference.

Claims

1. A closed-type kneader comprising: a kneading chamber having a kneading chamber; a material input section located above the kneading chamber and passing a material to be kneaded, made of polymer material, into the kneading chamber; a pair of kneading rotors arranged in the kneading chamber so as to be rotatable parallel to each other and configured to knead the material to be kneaded; a weight positioned in the material input section so as to be able to press down on the material to be kneaded in the kneading chamber from above; a hydraulic circuit having a hydraulic cylinder connected to the weight; and a controller that controls the hydraulic circuit to perform a pressing operation that supplies hydraulic fluid to the hydraulic cylinder so as to press down on the material to be kneaded by the weight, and a rapid rise suppression operation that restricts the movement of the hydraulic cylinder so as to suppress the upward movement speed of the weight when the pressing operation is released.

2. A closed-type kneader according to claim 1, further comprising a position detector for detecting the vertical position of the weight, the hydraulic circuit having a hydraulic servo valve capable of adjusting the direction and amount of hydraulic fluid supplied to the hydraulic cylinder, and the controller configured to calculate the movement speed of the weight from the time change of the position of the weight detected by the position detector during the rapid rise suppression operation, and to control the hydraulic servo valve so that the upward movement speed of the weight remains substantially constant.

3. A closed-type kneader according to claim 1, wherein the hydraulic cylinder has a first hydraulic chamber into which hydraulic fluid flows when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid flows when the weight is raised, the hydraulic circuit has a hydraulic servo valve configured to switch the direction of supply of hydraulic fluid to the first hydraulic chamber or the second hydraulic chamber, and a flow limiting valve that limits the flow rate of hydraulic fluid flowing out of the first hydraulic chamber to a predetermined level or less, and the controller is configured to control the hydraulic servo valve so that hydraulic fluid flows to the flow limiting valve during the rapid rise suppression operation, 4. A closed-type kneader according to claim 1, wherein the hydraulic cylinder has a first hydraulic chamber into which hydraulic fluid flows when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid flows when the weight is raised, the hydraulic circuit has a hydraulic servo valve configured to switch the direction of supply of hydraulic fluid to the first hydraulic chamber or the second hydraulic chamber, a return pipeline through which the hydraulic fluid that has flowed out of the first hydraulic chamber flows, and a flow rate limiting mechanism provided in the return pipeline, the flow rate limiting mechanism includes a flow rate limiting valve that limits the flow rate of hydraulic fluid flowing out of the first hydraulic chamber to below a predetermined level, and a shut-off valve that shuts off the outflow of hydraulic fluid from the first hydraulic chamber, and the controller controls the flow rate limiting mechanism such that the flow rate limiting valve of the flow rate limiting mechanism functions when the pressing operation is released by a command to raise the weight, and the shut-off valve of the flow rate limiting mechanism functions when the pressing operation is released by a power loss or emergency stop command.

5. A closed-type kneader according to claim 1, wherein the hydraulic cylinder has a first hydraulic chamber through which hydraulic fluid is introduced when the weight is lowered, and a second hydraulic chamber through which hydraulic fluid is introduced when the weight is raised, the hydraulic circuit has a return line through which the hydraulic fluid that has flowed out of the first hydraulic chamber flows, and a shut-off valve provided in the return line, and the controller controls the shut-off valve so as to shut off the flow of hydraulic fluid in the return line during the rapid rise suppression operation.

6. A closed-type kneader according to claim 1, wherein the hydraulic cylinder has a first hydraulic chamber into which hydraulic fluid flows when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid flows when the weight is raised, the hydraulic circuit has a hydraulic servo valve configured to switch the direction of supply of hydraulic fluid to the first hydraulic chamber or the second hydraulic chamber, a return line to return the hydraulic fluid that has flowed out of the first hydraulic chamber to the hydraulic servo valve, and a shut-off valve provided in a branch line branching off from the return line, the controller controls the hydraulic servo valve so as to stop the flow of hydraulic fluid in the return line and controls the shut-off valve so as to shut off the flow of hydraulic fluid in the branch line during the rapid rise suppression operation, a closed-type kneader.

7. A closed-type kneader according to claim 6, further comprising a relief valve provided in a bypass pipeline connected to the branch pipeline so as to bypass the shut-off valve.

8. A closed-type kneader according to claim 3, 4, or 6, wherein the hydraulic circuit further comprises a shut-off valve located in the pilot line of the hydraulic servo valve, the controller is configured to control the shut-off valve so as to shut off the flow of hydraulic fluid in the pilot line during the rapid rise suppression operation, and the hydraulic servo valve is configured to switch to a stopped state in which the supply of hydraulic fluid from the hydraulic servo valve is stopped when the hydraulic supply to the pilot line is stopped.

9. A closed-type kneader according to claim 4, 5, or 6, wherein the controller is configured to activate the shut-off valve when the pressing operation is released due to a loss of power.

10. A closed-type kneader according to claim 4, 5, or 6, wherein the controller is configured to activate the shut-off valve when the pressing operation is released by receiving an emergency stop command.

11. A closed-type kneader according to claim 1, further comprising a position detector for detecting the vertical position of the weight, the hydraulic cylinder having a first hydraulic chamber into which hydraulic fluid flows when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid flows when the weight is raised, the hydraulic circuit having a hydraulic servo valve capable of adjusting the direction and amount of supply of hydraulic fluid to the first hydraulic chamber or the second hydraulic chamber, a flow limiting valve for limiting the flow rate of hydraulic fluid in the return pipeline through which the hydraulic fluid that has flowed out of the first hydraulic chamber flows to a predetermined level or less, and a shut-off valve provided in the return pipeline, the controller configured to, in the rapid rise suppression operation, calculate the movement speed of the weight from the time change of the position of the weight detected by the position detector, control the hydraulic servo valve so that the upward movement speed of the weight becomes substantially constant and hydraulic fluid flows in the return pipeline, and control the shut-off valve so that the flow of hydraulic fluid in the return pipeline is shut off.

12. The sealed kneader according to claim 1, further comprising a position detector for detecting the vertical position of the weight, the hydraulic cylinder having a first hydraulic chamber into which hydraulic fluid flows when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid flows when the weight is raised, the hydraulic circuit having a hydraulic servo valve configured to switch the direction of supply of hydraulic fluid to the first hydraulic chamber or the second hydraulic chamber, a return line for returning the hydraulic fluid that has flowed out of the first hydraulic chamber to the hydraulic servo valve, a flow limiting valve for limiting the flow rate of hydraulic fluid flowing through the return line to a predetermined level or less, and a shut-off valve provided in a branch line branching from the return line, the controller controlling the hydraulic servo valve such that, in the rapid rise suppression operation, hydraulic fluid flows out of the first hydraulic chamber, the movement speed of the weight is calculated from the time change of the position of the weight detected by the position detector, the upward movement speed of the weight becomes substantially constant, and hydraulic fluid flows through the return line, A closed-type kneader configured to control the shut-off valve so as to block the flow of hydraulic fluid in the branch pipeline.

13. The sealed kneader according to claim 1, further comprising a position detector for detecting the vertical position of the weight, the hydraulic cylinder having a first hydraulic chamber into which hydraulic fluid flows when the weight is lowered, and a second hydraulic chamber into which hydraulic fluid flows when the weight is raised, the hydraulic circuit having a hydraulic servo valve configured to switch the direction of supply of hydraulic fluid to the first hydraulic chamber or the second hydraulic chamber, a return line for returning the hydraulic fluid that has flowed out of the first hydraulic chamber to the hydraulic servo valve, a flow limiting valve for limiting the flow rate of the hydraulic fluid flowing through the return line to a predetermined level or less, and a shut-off valve located in the pilot line of the hydraulic servo valve, the controller controlling the hydraulic servo valve such that, in the rapid rise suppression operation, hydraulic fluid flows out of the first hydraulic chamber, the moving speed of the weight is calculated from the time change of the position of the weight detected by the position detector, the upward moving speed of the weight becomes substantially constant, and hydraulic fluid flows through the return line, A closed-type kneader configured to control the shut-off valve so as to block the flow of hydraulic fluid in the pilot pipeline.

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