Sealed type kneader

Abstract

To provide a sealed type kneader capable of reducing a supply amount of a lubricant supplied to a leakage prevention part while reducing a wear of the leakage prevention part.SOLUTION: A sealed type kneader increases a supply amount R of a lubricant supplied to a leakage prevention part 100 in a material-taking-in period in which a to-be-kneaded material is likely to leak from the leakage prevention part 100, therefore, it can reduce a wear of the leakage prevention part while suppressing a leakage of the to-be-kneaded material from the leakage prevention part 100. Also, in a period other than the material-taking-in period, the to-be-kneaded material is less likely to leak compared to the material-taking-in period, therefore, the supply amount R of the lubricant can be reduced by reducing the supply amount R of the lubricant supplied to the leakage prevention part 100 in this period.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to the supply of lubricating oil to a leak-proof section of an internal mixer. [Background technology]

[0002] There is known an internal mixer that mixes materials to be mixed, such as rubber and plastic, with various additives. Patent Document 1 discloses such an internal mixer having a chamber and a pair of mixing rotors. The chamber forms a mixing chamber, and the pair of mixing rotors are arranged side by side in the mixing chamber and rotate. A shear force is applied to the materials to be mixed between the pair of mixing rotors and the chamber, and the materials to be mixed are mixed.

[0003] Furthermore, the technology described in Patent Document 1 is equipped with a lubricating oil supply mechanism that supplies lubricating oil to the leakage prevention section (also called the sealing section) between the kneading rotor and the chamber, measures the temperature of the leakage prevention section while kneading the material to be kneaded, and adjusts the amount of lubricating oil supplied based on the measured temperature.

[0004] In addition, the technology described in Patent Document 2 is equipped with a lubricating oil supply device that supplies lubricating oil to the leakage prevention section between the kneading rotor and the chamber, and the amount of lubricating oil supplied to the leakage prevention section is adjusted according to the rotation speed of the kneading rotor.

[0005] In addition, the technology described in Patent Document 3 includes a rotating side seal member that rotates integrally with the kneading rotor, and a ring-shaped fixed side seal member that rotatably passes through the rotor shaft of the kneading rotor, and further includes a lubricating oil supply mechanism that supplies lubricating oil between the fixed side seal member and the rotating side seal member.

[0006] In addition, the technology described in Patent Document 4 is equipped with a lubricating oil supply mechanism that supplies lubricating oil to the leakage prevention section between the kneading rotor and the chamber, and during standby mode when the material to be kneaded has been removed from the chamber, the amount of lubricating oil supplied from the lubricating oil supply mechanism is reduced compared to when the material to be kneaded is present in the chamber. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2021-98316 [Patent Document 2] Patent No. 6526439 [Patent Document 3] Patent No. 5356045 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-78297 Summary of the Invention [Problem to be solved by the invention]

[0008] The kneaders described in Patent Documents 1 to 4 all suppress wear of the leakage prevention section by supplying lubricating oil to the leakage prevention section between the kneading rotor and the chamber. However, from the perspective of the environment and operating costs, it is desirable to reduce the amount of lubricating oil supplied to the leakage prevention section. In contrast, for example, in the technology described in Patent Document 1, a constant pressing pressure is always applied to the leakage prevention section, so a predetermined amount or more of lubricating oil must be continuously supplied to suppress wear of the leakage prevention section even when pressing pressure is not required. Furthermore, while the technology described in Patent Document 2 describes reducing the amount of lubricating oil supplied during the period until the kneading rotor reaches 50% of its maximum rotation speed, it does not take into consideration reducing the amount of lubricating oil supplied during the series of kneading steps for kneading the material to be kneaded. Furthermore, Patent Document 4 describes reducing the amount of lubricating oil supplied during a standby mode after the material to be kneaded is removed from the chamber, but does not take into consideration reducing the amount of lubricating oil supplied during the series of kneading steps for kneading the material to be kneaded. Patent Document 3 does not describe adjusting the amount of lubricating oil supplied.

[0009] An object of the present invention is to provide an internal mixer that can reduce the amount of lubricating oil supplied to the leakage prevention section while reducing wear on the leakage prevention section. [Means for solving the problem]

[0010] The inventors conducted extensive research into the above-mentioned problems and discovered that during the material intake period, when the material to be kneaded is taken into the chamber, the material to be kneaded is more likely to leak from the leakage prevention section than during other periods in the kneading process of the material to be kneaded, whereas during periods other than the material intake period, the material to be kneaded is less likely to leak from the leakage prevention section and less lubricating oil needs to be supplied, leading to the present invention.

[0011] The first aspect of the internal mixer comprises a casing having a chamber therein for accommodating the material to be mixed, a mixing rotor including a rotor shaft extending outside the chamber and a mixing blade disposed inside the chamber, which rotates to mix the material to be mixed in the chamber, a weight mounted on the casing so as to be able to move up and down and which pushes the material to be mixed into the chamber, a leakage prevention unit which prevents the material to be mixed in the chamber from leaking out of the chamber, and a lubricating oil supply mechanism which supplies lubricating oil to the leakage prevention unit, wherein the leakage prevention unit comprises a fixed side seal member attached to the casing so as to surround the rotor shaft, and a rotating side seal member attached to the rotor shaft so as to face the fixed side seal member and which can rotate while sliding against the fixed side seal member, and the lubricating oil supply mechanism increases the amount of lubricating oil supplied to the leakage prevention unit during a material intake period in which the material to be mixed is taken into the chamber.

[0012] According to the first aspect, the amount of lubricating oil supplied to the leakage prevention part is increased during the material intake period when the material to be kneaded is likely to leak from the leakage prevention part, thereby reducing wear on the leakage prevention part while suppressing leakage of the material to be kneaded from the leakage prevention part. Furthermore, since the material to be kneaded is less likely to leak during periods other than the material intake period than during the material intake period, the amount of lubricating oil supplied to the leakage prevention part can be reduced by reducing the amount of lubricating oil supplied during these periods.

[0013] In a second aspect, it is desirable that the closed-type mixer according to the first aspect further comprises the following feature. That is, the closed-type mixer according to the second aspect further comprises a sealing and pressurizing mechanism that increases the pressure applied between the fixed-side seal member and the rotating-side seal member during the material intake period. According to the second aspect, since the material to be mixed is likely to leak from the leakage prevention section during the material intake period, the pressure applied between the fixed-side seal member and the rotating-side seal member by the sealing and pressurizing mechanism can be increased during the material intake period, thereby preventing the material to be mixed from leaking from the leakage prevention section. Furthermore, since the amount of lubricating oil supplied to the leakage prevention section is increased during the material intake period compared to other periods, wear on the leakage prevention section can be reduced even if the pressure between the fixed-side seal member and the rotating-side seal member increases.

[0014] In a third aspect, it is desirable for the internal mixer according to the first or second aspect to further include the following feature. That is, in the internal mixer according to the third aspect, the material intake period includes at least a part of a period during which the weight pushes the material to be mixed after the material to be mixed is introduced into the chamber and until the weight reaches a predetermined lower limit position. According to the third aspect, the material to be mixed is most likely to leak from the leakage prevention section during the period during which the weight pushes the material to be mixed after the material to be mixed is introduced into the chamber and until the weight reaches a predetermined lower limit position. Therefore, by including at least a part of the material intake period, the amount of lubricating oil supplied to the leakage prevention section during the process of kneading the material to be mixed can be appropriately distributed, and the amount of lubricating oil supplied during the kneading process can be reduced.

[0015] In a fourth aspect, it is desirable that the closed-type mixer according to any one of the first to third aspects further comprises the following feature. That is, the closed-type mixer according to the fourth aspect further comprises a seal gap measurement unit that measures the seal gap between the fixed-side seal member and the rotating-side seal member, and a material leakage warning unit that issues a warning when the seal gap measured by the seal gap measurement unit becomes equal to or greater than a predetermined value. If the seal gap between the fixed-side seal member and the rotating-side seal member becomes large, there is a risk that the material to be mixed will leak from the leakage prevention unit. In contrast, according to the fourth aspect, a warning is issued from the material leakage warning unit when the seal gap becomes equal to or greater than a predetermined value, making it possible to detect signs of leakage of the material to be mixed.

[0016] A fifth aspect is preferably the closed-type mixer according to any one of the second to fourth aspects, further comprising the following feature: That is, the closed-type mixer according to the fifth aspect further comprises a seal gap measurement unit that measures the seal gap between the fixed-side seal member and the rotating-side seal member, and when the seal gap measured by the seal gap measurement unit reaches a predetermined value or greater, the seal pressurizing mechanism further increases the pressure applied between the fixed-side seal member and the rotating-side seal member. According to the fifth aspect, when it is detected based on the seal gap that there is a risk of the material to be mixed leaking from the leakage prevention unit, the pressure between the fixed-side seal member and the rotating-side seal member is further increased, thereby making it possible to suppress leakage of the material to be mixed.

[0017] In a sixth aspect, in the closed-type mixer according to the second or fifth aspect, the seal pressurizing mechanism has a pressing part that presses the fixed-side seal member against the rotating-side seal member, and the lubricating oil supply mechanism has an oil inlet that penetrates the fixed-side seal member and supplies lubricating oil between the fixed-side seal member and the rotating-side seal member, the oil inlet being formed near a portion of the fixed-side seal member that is pressed by the pressing part. According to the sixth aspect, the lubricating oil is supplied in a concentrated manner to portions of the fixed-side seal member and the rotating-side seal member that are prone to wear, so that the lubricating oil is supplied efficiently and the amount of lubricating oil supplied can be further reduced. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an internal mixer that can reduce the amount of lubricating oil supplied to the leakage prevention section while reducing wear on the leakage prevention section. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view of an internal mixer according to one embodiment of the present invention. [Figure 2] FIG. 2 is a front view showing a leakage prevention part of an internal mixer according to one embodiment of the present invention. [Figure 3] FIG. 1 is a perspective view schematically showing an oil supply structure to a leakage prevention part of an internal mixer according to one embodiment of the present invention. [Figure 4] 10 is a time chart illustrating a change in the position of a weight during a kneading process of a material to be kneaded. [Figure 5] 10 is a time chart illustrating changes in the amount of lubricant oil supplied and the pressing pressure during the kneading process. [Figure 6] 10 is a time chart illustrating the behavior of the seal gap when leakage of the material to be mixed occurs and when leakage does not occur during the material intake period. [Figure 7] 10 is a flowchart illustrating the control operation of the electronic control device in a kneading process of the material to be kneaded. DETAILED DESCRIPTION OF THE INVENTION

[0020] [Overall structure] Hereinafter, a kneader 1 (internal kneader) according to one embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view of the kneader 1 according to this embodiment. Fig. 2 is a front view showing a leakage prevention section 100 of the kneader 1. Fig. 3 is a perspective view schematically showing an oil supply structure to the leakage prevention section 100 of the kneader 1.

[0021] 1, the kneader 1 includes a pair of kneading rotors 2, a casing 3, a chamber 4, a weight 5, and a drop door 6. The chamber 4 is a space formed inside the casing 3 for accommodating an object to be kneaded, such as a polymer material.

[0022] The pair of kneading rotors 2 knead the material to be kneaded within the chamber 4 by rotating. Each kneading rotor 2 has a rotor shaft 2A and a kneading blade 2B. The rotor shaft 2A extends to the outside of the chamber 4 and is rotatably supported by the casing 3. The kneading blade 2B is disposed inside the chamber 4 and is a blade that protrudes radially outward from the rotor shaft 2A. The kneading blade 2B applies a shear force to the material to be kneaded by rotating.

[0023] The inner wall of the casing 3 is formed in a cocoon shape in the longitudinal section shown in Fig. 1, and end plates 8 are joined to both side surfaces of the casing 3 in the direction perpendicular to the paper surface of Fig. 1, as shown in Fig. 2. As a result, a chamber 4 including a pair of left and right kneading chambers 4a is formed so as to be able to accommodate the material to be kneaded inside.

[0024] An inlet 3a is formed in the upper center of the casing 3, through which the material to be mixed is introduced into the chamber 4. A weight 5 is provided in the inlet 3a of the casing 3 so as to be able to move up and down, and the weight 5 pushes the material to be mixed introduced into the chamber 4 into the mixing chamber 4a of the chamber 4. Meanwhile, an outlet 3b is formed in the lower center of the chamber 4 so that the material to be mixed in the desired mixed state can be discharged to the outside, and a drop door 6 is provided to open and close the outlet 3b. The weight 5 and drop door 6 come into close contact with the casing 3 during mixing, thereby constituting part of the inner wall surface of the chamber 4.

[0025] The weight 5 is configured to be able to rise and fall between a lower limit position Plow indicated by a solid line and an upper limit position Phi indicated by a two-dot chain line. The upper limit position Phi is the highest position to which the weight 5 can rise, and when the weight 5 moves to the upper limit position Phi, the feed port 3a opens and the material to be mixed can be fed into the chamber 4 through the feed port 3a. The lower limit position Plow is the lowest position to which the weight 5 can fall, and when the weight 5 falls to the lower limit position Plow, the material to be mixed is filled in a sealed state inside the kneading chamber 4a. The weight 5 may be configured to be able to rise and fall by, for example, a cylinder mechanism, a ball screw, or the like, or may be configured to be able to rise and fall by another mechanism.

[0026] [Leak prevention structure] The kneader 1 further includes a leakage prevention unit 100 shown in Figures 2 and 3. The leakage prevention unit 100 functions as a dust seal (sealing unit) for preventing the material to be kneaded filled in the kneading chamber 4a of the chamber 4 from leaking out from the end of the kneading rotor 2 to the outside of the kneading chamber 4a.

[0027] The leakage prevention unit 100 has a rotating-side seal member 9, a fixed-side seal member 10, a plurality of cooling water pipes 16, a plurality of lubricating oil pipes 18, a yoke 20, a pair of yoke pins 21, yoke rivets 22, and a hydraulic cylinder 23. Furthermore, the kneader 1 has a lubricating oil supply mechanism 50 that supplies lubricating oil to the leakage prevention unit 100 (see FIG. 3).

[0028] The stationary-side seal member 10 has a ring shape and is attached to the casing 3 so as to surround the rotor shaft portion 2A. The rotating-side seal member 9 has a ring shape and is attached to the rotor shaft portion 2A so as to face the stationary-side seal member 10. The rotating-side seal member 9 is rotatable integrally with the rotor shaft portion 2A while sliding relative to the stationary-side seal member 10. In other words, the rotating-side seal member 9 rotates, while the stationary-side seal member 10 does not rotate. The rotating-side seal member 9 and the stationary-side seal member 10 have ring-shaped opposing surfaces (sliding surfaces, sealing surfaces) that face each other.

[0029] The fixed-side seal member 10 is fitted in a liquid-tight manner to the end plate 8 via a seal ring (not shown) on the kneading rotor 2 side to prevent leakage of the material to be kneaded or the lubricating oil to the outside. As shown in Fig. 2, a cooling water pipe 16 and a lubricating oil pipe 18 are connected to the end plate 8, and the fixed-side seal member 10 is cooled by cooling water flowing into the cooling water pipe 16. Furthermore, lubricating oil flows into each lubricating oil pipe 18 from a lubricating oil supply mechanism 50 shown in Fig. 3, and the lubricating oil is supplied to a sliding portion 14 where the opposing surfaces of the fixed-side seal member 10 and the rotating-side seal member 9 slide against each other.

[0030] The opposing surfaces of the rotating seal member 9 and the stationary seal member 10 are formed of, for example, hard-clad metal. Materials that can be used for these opposing surfaces include various steels and copper alloys, as well as non-oil-impregnated materials such as ceramics and sintered carbon, and oil-impregnated metals such as gunmetal, cast iron, and sintered metal.

[0031] The yoke 20 is a plate member for transmitting the operating force of the hydraulic cylinder 23 to the fixed-side seal member 10. The hydraulic cylinder 23 is attached to one end of the yoke 20, and a yoke pin 21 is attached to each of the other two bifurcated ends. A yoke rivet 22 is inserted through the bifurcated portion of the yoke 20 (approximately the center of the yoke 20), and the yoke 20 swings around this yoke rivet 22 as a fulcrum. The yoke rivet 22 is fixed to the end plate 8, and the yoke 20 is supported by the end plate 8 at the yoke rivet 22. The tip ends of the two yoke pins 21 are fitted into holes formed in the end surface of the fixed-side seal member 10 on the outer side of the rotor shaft portion 2A.

[0032] The fixed-side seal member 10 is prevented from rotating by yoke pins 21 attached to the bifurcated ends of the yoke 20. The rotation of the fixed-side seal member 10 is more reliably prevented by the hydraulic cylinder 23 pressing the yoke pins 21 against the fixed-side seal member 10 via the yoke 20. The fixed-side seal member 10 is also pressed against the rotating-side seal member 9 via the yoke pins 21, thereby preventing the material to be kneaded from leaking from the sliding portion 14 between the fixed-side seal member 10 and the rotating-side seal member 9. The yoke pins 21 correspond to the pressing portion of the present invention that presses the fixed-side seal member against the rotating-side seal member.

[0033] The hydraulic cylinder 23 is a linear actuator having a cylinder body (not shown) and a piston rod, and is configured to linearly move the piston rod by supplying and discharging hydraulic oil therein. The yoke 20, the pair of yoke pins 21, the yoke rivets 22, and the hydraulic cylinder 23 constitute a pressing mechanism 48 (seal pressure mechanism) that applies pressing pressure Ps between the fixed-side seal member 10 and the rotating-side seal member 9.

[0034] The hydraulic pressure of the hydraulic oil inside the hydraulic cylinder 23 can be adjusted by a hydraulic control valve 24. The hydraulic control valve 24 uses the hydraulic pressure generated by a hydraulic pressure generator 26 as the source pressure and controls the hydraulic pressure of the hydraulic oil supplied to the hydraulic cylinder 23. The hydraulic control valve 24 controls the hydraulic pressure of the hydraulic oil based on a hydraulic pressure signal output from an electronic control device 28.

[0035] The electronic control device 28 is configured as a computer including a central processing unit (CPU) (not shown) and storage devices such as ROM and RAM (not shown), and performs various processes, including hydraulic control of the hydraulic oil supplied to the hydraulic cylinder 23. Various signals are input to the electronic control device 28, such as a signal representing the weight position Po, which is the position of the weight 5, detected by a position sensor 30; a signal representing the pressing pressure Ps (seal pressure) applied between the stationary seal member 10 and the rotating seal member 9, detected by a pressing pressure detection sensor 32; and a signal representing the seal gap S between the stationary seal member 10 and the rotating seal member 9, measured by an eddy current sensor 34. The pressing pressure detection sensor 32 may detect the hydraulic pressure of the hydraulic oil in the hydraulic cylinder 23 and calculate the pressing pressure Ps based on the hydraulic pressure. The eddy current sensor 34 corresponds to a seal gap measurement unit that measures the seal gap in the present invention.

[0036] As shown in FIG. 3, the lubricating oil supply mechanism 50 includes a motor 51, an oil supply mechanism 52, a lubricating oil tank 53, an oil amount adjusting mechanism 54, and a controller 60.

[0037] The oil supply mechanism 52 includes a crankshaft 52A and three discharge cylinders 52B (plungers) connected to the three crank portions of the crankshaft. The motor 51 rotates in response to a command signal from the controller 60, rotating the crankshaft 52A in the oil supply mechanism 52. Each discharge cylinder 52B functions as a plunger pump. It draws lubricating oil from a lubricating oil tank 53 and discharges the lubricating oil toward the leakage prevention unit 100 as the crankshaft 52A rotates. The lubricating oil is supplied through the lubricating oil piping 18 shown in FIG. 2 and flows into an oil inlet 18A formed in the fixed-side seal member 10. The oil inlet 18A penetrates the fixed-side seal member 10 and communicates with the sliding portion 14 between the fixed-side seal member 10 and the rotating-side seal member 9. This allows the lubricating oil to be supplied to the sliding portion 14 via the oil inlet 18A. As a result, a lubricating oil layer W (FIG. 3) is formed in the sliding portion 14. The three crank portions of the crankshaft 52A are arranged at 120-degree intervals along the rotation direction, and are set with an equal phase difference from one another.

[0038] The oil amount adjusting mechanism 54 adjusts the stroke of the piston of the discharge cylinder 52B when the crankshaft 52A of the oil supply mechanism 52 makes one rotation, thereby adjusting the amount of lubricating oil discharged from each discharge cylinder 52B. The oil amount adjusting mechanism 54 may be operated by an operator, or may adjust the stroke of the piston in response to a command signal received from the controller 60.

[0039] 3, in this embodiment, lubricating oil is supplied to the sliding portion 14 between the stationary seal member 10 and the rotating seal member 9 from three oil inlets 18A formed in the stationary seal member 10. At this time, the phase difference between the three crank portions of the crankshaft of the lubricating oil supply mechanism 50 causes the lubricating oil to be supplied to each oil inlet 18A in sequence.

[0040] The lubricating oil supply mechanism 50 periodically repeats lubricating oil supply and stop operations so as to intermittently supply lubricating oil to the sliding part 14 between the rotating-side seal member 9 and the stationary-side seal member 10. This reduces the total supply amount R of lubricating oil supplied to the sliding part 14, while stably maintaining the seal gap S (oil film thickness) required for the sliding part 14, compared to when lubricating oil is continuously supplied to the sliding part 14. As a result, the reduction in the lubricating oil supply amount R reduces the environmental impact of wasted oil and also makes it possible to reduce the running costs of the kneader 1. Furthermore, in this embodiment, the lubricating oil is intermittently supplied by the lubricating oil supply mechanism 50, which prevents momentary oil leakage from the sliding part 14 due to the pulsed supply action, thereby further improving the lubricating effect.

[0041] 3, two of the three oil filler ports 18A are formed near a portion of the stationary seal member 10 that is pressed by the yoke pin 21. This allows the lubricating oil to be concentrated in a portion of the sliding portion 14 between the rotating seal member 9 and the stationary seal member 10 that is prone to wear, further reducing the amount of lubricating oil supplied R. As an example of the definition of the vicinity of the portion that is pressed by the yoke pin 21, the circumferential distance between the oil filler port 18A and the yoke pin 21 relative to the midpoint of the two yoke pins 21 in the circumferential direction is smaller than the circumferential distance between the oil filler port 18A and the midpoint. The oil filler ports 18A are positioned so that the circumferential distance between the oil filler port 18A and the yoke pin 21 is 30% or less, preferably 20% or less, and more preferably 10% or less of the circumferential distance between the midpoint and the yoke pin 21.

[0042] As described above, the leakage prevention unit 100 supplies lubricating oil to the sliding portion 14 between the rotating-side seal member 9 and the fixed-side seal member 10 via the lubricating oil supply mechanism 50, while pressing the fixed-side seal member 10 toward the rotating-side seal member 9 using the pressing mechanism 48. This allows the pressing pressure Ps (sealing pressure) between the rotating-side seal member 9 and the fixed-side seal member 10 to be set to a value that suppresses leakage of the material to be kneaded, thereby suppressing leakage of the material to be kneaded from the leakage prevention unit 100.

[0043] Next, the kneading process of the material to be kneaded will be described. Fig. 4 is a time chart illustrating the position of the weight position Po, which is the position of the weight 5, during the kneading process of the material to be kneaded. In Fig. 4, the horizontal axis represents time t [sec], and the vertical axis represents the weight position Po [mm], which is the position of the weight 5 in the vertical direction.

[0044] Period A shown in Figure 4 is a period during which the material to be mixed is introduced into chamber 4. During period A, weight 5 is positioned at the upper limit position Phi, allowing the material to be mixed to be introduced into chamber 4. At this time, additives such as filler may be added as appropriate. Period B is the period from when weight 5 starts to descend after the material to be mixed is introduced into chamber 4 until weight 5 reaches the lower limit position Plow, i.e., the material intake period during which the material to be mixed is taken into kneading chamber 4a. Period C is a weight up / down period during which weight 5 is temporarily raised after the material is taken in. Period D is a material mixing period during which the material to be mixed is mixed in kneading chamber 4a of chamber 4. Period E is a material discharge period during which drop door 6 is removed and the material to be mixed is removed from chamber 4.

[0045] In period A, immediately after the material to be mixed is charged into the chamber 4, the weight 5 is located at the upper limit position Phi. At this time, the amount of the material to be mixed is greater than the capacity of the kneading chamber 4a of the chamber 4, and the material to be mixed overflows up to the vicinity of the charge port 3a. In period B, the weight 5 descends from the upper limit position Phi, and the weight 5 pushes the material to be mixed into the kneading chamber 4a. In period C, the weight 5 temporarily rises and descends to the lower limit position Plow, and then in period D the material to be mixed is kneaded. As the material to be mixed is mixed between periods B and D, the volume of the material to be mixed gradually decreases, and the filling rate of the material to be mixed in the kneading chamber 4a becomes lower than 100%. In period E, with the weight 5 located at the lower limit position Plow, the drop door 6 is removed and the material to be mixed is removed from the discharge port 3b.

[0046] Here, it was confirmed that during the material intake period (corresponding to period B in FIG. 4 ) in which the material to be kneaded is taken into the kneading chamber 4a of the chamber 4, the material to be kneaded is prone to leak from the leakage prevention part 100. During the material intake period, the weight 5 pushes the material to be kneaded into the kneading chamber 4a. Immediately after the material to be kneaded is introduced into the chamber 4, the volume of the material to be kneaded exceeds the volume of the kneading chamber 4a, and the filling rate of the material to be kneaded in the kneading chamber 4a exceeds 100%. Therefore, during the transitional period in which the weight 5 descends during the material intake period, the weight 5 pushes the material to be kneaded. At this time, the weight 5 presses the material to be kneaded, generating an outward force on the material to be kneaded. It is believed that this force becomes greater than the pressing pressure Ps applied between the stationary-side seal member 10 and the rotating-side seal member 9, making the material to be kneaded prone to leak from the leakage prevention part 100.

[0047] To prevent leakage of the material to be mixed during the material intake period, it is necessary to increase the pressing pressure Ps applied to the sliding portion 14 between the rotating seal member 9 and the fixed seal member 10 of the leakage prevention unit 100. On the other hand, increasing the pressing pressure Ps makes the sliding portion 14 more susceptible to wear. In response to this, the electronic control unit 28 increases the pressing pressure Ps applied to the sliding portion 14 during the material intake period compared to other periods. Furthermore, the electronic control unit 28 increases the supply amount R of lubricating oil supplied from the lubricating oil supply mechanism 50 to the leakage prevention unit 100 compared to the other periods. The other periods correspond to period A and periods C to E in FIG. 4.

[0048] The electronic control device 28 functionally includes a pressing pressure control unit 80 that controls the pressing pressure Ps applied to the sliding portion 14 between the fixed side seal member 10 and the rotating side seal member 9 of the leakage prevention unit 100, and a lubricating oil quantity control unit 82 that controls the supply amount R of lubricating oil supplied from the lubricating oil supply mechanism 50 to the leakage prevention unit 100.

[0049] The pressing pressure control unit 80 determines whether or not it is the material intake period. The material intake period is set to the period from the time when the material to be mixed is put into the chamber 4 to the time when the weight 5 reaches the lower limit position Plow. The pressing pressure control unit 80 determines whether or not it is the material intake period based on, for example, the weight position Po of the weight 5 detected by the position sensor 30. Note that the determination of whether or not it is the material intake period may be made by the lubricant amount control unit 82.

[0050] The start of the material intake period may be, for example, the time when the weight 5 starts to descend, or the time when the weight 5 descends to a predetermined position just before contacting the material to be mixed. The predetermined position can be determined in advance based on experiments, etc. Alternatively, it may be the time when the weight 5 actually comes into contact with the material to be mixed. In this case, it is possible to determine whether the weight 5 has come into contact with the material to be mixed, for example, by detecting the load on the weight 5.

[0051] The end of the material intake period may be the point at which a predetermined time has elapsed since the start of the material intake period, or may be the point at which the weight 5 starts to rise. The predetermined time is the time required for the weight 5 to descend to the lower limit position Plow, and can be determined in advance based on experiments, etc. In this way, the material intake period only needs to include at least a portion of the period during which the weight 5 pushes the material to be mixed between the time when the material to be mixed is charged into the chamber 4 and the time when the weight 5 reaches the lower limit position Plow.

[0052] If it is the material intake period, the pressing pressure control unit 80 increases the pressing pressure Ps applied to the sliding unit 14 of the leakage prevention unit 100 compared to other periods other than the material intake period. Specifically, the pressing pressure control unit 80 increases the pressing pressure Ps applied to the sliding unit 14 by increasing the hydraulic pressure of the hydraulic oil supplied to the hydraulic cylinder 23. The pressing pressure Ps during the material intake period is determined in advance experimentally or by design, and is set to a value that can prevent the material to be kneaded from leaking from the leakage prevention unit 100. As a result, the material to be kneaded is prevented from leaking from the leakage prevention unit 100 during the material intake period.

[0053] Furthermore, when the pressing pressure Ps applied to the sliding part 14 of the leakage prevention part 100 increases, the sliding part 14 becomes more susceptible to wear. In response to this, the lubricant amount control part 82 increases the supply amount R of lubricant supplied from the lubricant supply mechanism 50 to the leakage prevention part 100 during the material intake period compared to other periods other than the material intake period. The lubricant amount control part 82 increases the supply amount R of lubricant supplied to the leakage prevention part 100 by increasing the rotation speed of the motor 51 during the material intake period compared to other periods and by increasing the stroke of the discharge cylinder 52B of the oil amount adjustment mechanism 54. As a result, while the sliding part 14 becomes more susceptible to wear during the material intake period, the increase in the supply amount R of lubricant supplied to the leakage prevention part 100 reduces wear of the sliding part 14.

[0054] Furthermore, during periods other than the material intake period, the pressing pressure Ps applied to the leakage prevention unit 100 is smaller than during the material intake period. Even if the pressing pressure Ps is smaller, the material to be kneaded is less likely to leak from the leakage prevention unit 100 during periods other than the material intake period, so leakage of the material to be kneaded is suppressed, just as in the material intake period. Furthermore, when the pressing pressure Ps is smaller, the load on the sliding unit 14 is reduced, making the sliding unit 14 less likely to wear. Therefore, the supply amount R of lubricating oil supplied to the leakage prevention unit 100 during other periods can be reduced compared to the material intake period, and as a result, the total supply amount of lubricating oil in the kneading process can be reduced.

[0055] Fig. 5 is a time chart illustrating the changes in the lubricant supply rate R [cc / s] and the pressing pressure Ps [MPa] during the kneading process. In Fig. 5, the horizontal axis represents time t [sec], and the vertical axis represents the weight position Po [mm] of the weight 5, the lubricant supply rate R [cc / s], and the pressing pressure Ps [N], respectively.

[0056] The weight position Po indicated by the solid line in FIG. 5 is the same as that shown in FIG. 4, and therefore its description will be omitted. The pressing pressure Ps indicated by the dashed line increases during the material intake period (period B) compared to other periods. Specifically, the pressing pressure Ps during periods other than the material intake period is the second pressure Ps2, whereas during the material intake period, the pressing pressure Ps becomes the first pressure Ps1, which is higher than the second pressure Ps2. Note that the second pressure Ps2 of the pressing pressure Ps may be, for example, approximately one-third of the first pressure Ps1. Similarly, the lubricating oil supply rate R [cc / s] indicated by the dashed line increases during the material intake period compared to other periods. Specifically, the supply rate R during other periods is the second oil rate R2, whereas during the material intake period, the first oil rate R1 is greater than the second oil rate R2. Note that the second oil rate R2 of the supply rate R may be, for example, approximately one-third of the first oil rate R1.

[0057] Furthermore, when a wear test was conducted while controlling the pressing pressure Ps and the lubricant supply rate R in the kneading process as shown in Fig. 5, the amount of wear of the sliding part 14 was kept to 1 µm or less even after 8 hours. In this way, even if the pressing pressure Ps is reduced and the lubricant supply rate R is decreased during periods other than the material intake period, the wear of the sliding part 14 can be suppressed.

[0058] Incidentally, in the wear test, when the material to be kneaded leaks from the leakage prevention part 100 during the material intake period, the seal gap S between the fixed side seal member 10 and the rotating side seal member 9 increases. Figure 6 is a time chart that explains the behavior of the seal gap S when leakage of the material to be kneaded occurs and when it does not occur during the material intake period. In Figure 6, the dashed line shows the seal gap Sa when leakage of the material to be kneaded does not occur, and the solid line shows the seal gap Sb when leakage of the material to be kneaded occurs.

[0059] When the material to be mixed does not leak, as shown by the dashed line, the seal gap Sa remains almost unchanged even during the material intake period (period B), and the seal gap Sa remains approximately at its initial state. On the other hand, when the material to be mixed leaks, as shown by the solid line, the seal gap Sb fluctuates during the material intake period and temporarily exceeds 0.4 mm. In other words, when the material to be mixed leaks, the seal gap S increases by 0.3 mm or more during the material intake period compared to the initial value (0.0 mm) of period B. This also shows that the seal gap S tends to converge after period B has passed. From this, it is possible to detect signs of leakage of the material to be mixed by measuring the seal gap S.

[0060] Therefore, the electronic control device 28 is functionally equipped with a leakage sign detection unit 84 that detects signs of leakage of the material to be mixed based on the seal gap S. The leakage sign detection unit 84 determines that there is a sign of leakage of the material to be mixed when the seal gap S measured at any time by the eddy current sensor 34 during the material intake period becomes equal to or greater than a predetermined value Sth. The predetermined value Sth is determined in advance experimentally or analytically and is set to a value at which it can be determined that there is a risk of leakage of the material to be mixed. When the leakage sign detection unit 84 detects a sign of leakage of the material to be mixed, that is, when the seal gap S measured by the eddy current sensor 34 becomes equal to or greater than the predetermined value Sth, it causes the alarm 36 to output an alarm sound. This allows the operator to know that there is a sign of leakage of the material to be mixed. The alarm 36 corresponds to the material leakage warning unit of the present invention.

[0061] Furthermore, when the pressing pressure control unit 80 detects signs of leakage of the material to be kneaded, it further increases the pressing pressure Ps applied to the sliding unit 14. The pressing pressure Ps at this time is higher than the first pressure Ps1 set during the material intake period. For example, when the pressing pressure control unit 80 detects signs of leakage of the material to be kneaded, it corrects the pressing pressure Ps to the increasing side by performing feedback control using the difference (=|S-Sth|) between the seal gap S measured at any time and a predetermined value Sth as the deviation. This allows the pressing pressure Ps to be appropriately adjusted according to the seal gap S, and makes it possible to reliably suppress leakage of the material to be kneaded.

[0062] Fig. 7 is a flowchart illustrating the control operation of the electronic control device 28 during the kneading process. The flowchart in Fig. 7 explains the control for adjusting the pressing pressure Ps applied to the sliding part 14 and the supply amount R of lubricating oil during the kneading process of the material to be kneaded. The steps in this flowchart are repeatedly executed during the kneading process.

[0063] When mixing of the material to be mixed is started, the electronic control device 28 determines whether or not it is a material intake period (S10). If it is not a material intake period (No in S10), the electronic control device 28 controls the pressing pressure Ps to a second pressure Ps2 that is set for periods other than the material intake period (S60). Furthermore, the electronic control device 28 controls the supply rate R of lubricating oil to a second oil rate R2 that is set in advance for periods other than the material intake period (S60). On the other hand, if it is a material intake period (Yes in S10), the electronic control device 28 increases the pressing pressure Ps compared to other periods (S20). Specifically, the electronic control device 28 controls the pressing pressure Ps to a first pressure Ps1 that is higher than the second pressure Ps2. Furthermore, the electronic control device 28 increases the supply rate R of lubricating oil compared to other periods (S20). Specifically, the electronic control device 28 controls the supply rate R to a first oil rate R1 that is greater than the second oil rate R2. Next, the electronic control device 28 determines whether the seal clearance S is equal to or greater than a predetermined value Sth (S30). If the seal clearance S is less than the predetermined value Sth (No in S30), the electronic control device 28 maintains the pressing pressure Ps at the first pressure Ps1 and the supply rate R at the first oil rate R1. On the other hand, if the seal clearance S is equal to or greater than the predetermined value Sth (Yes in S30), the electronic control device 28 executes control to further increase the pressing pressure Ps in accordance with the seal clearance S (S40). In addition, the lubricant supply rate may be further increased. An alarm may also be sounded from the alarm 36. Next, the electronic control device 28 determines whether a period other than the material intake period has begun (S50). If it is currently the material intake period (No in S50), the electronic control unit 28 returns to S30 and continues to execute the control for the material intake period. On the other hand, if it is now a period other than the material intake period (Yes in S50), the electronic control unit 28 controls the pressing pressure Ps to the second pressure Ps2 and the lubricating oil supply rate R to the second oil rate R2 (S60).

[0064] [effect] As described above, during the material intake period of the kneading process, when the material to be kneaded is more likely to leak than during other periods, increasing the pressing pressure Ps applied to the sliding portion 14 between the fixed seal member 10 and the rotating seal member 9 suppresses leakage of the material to be kneaded. Furthermore, by simultaneously increasing the lubricant supply rate R during the material intake period, wear on the leakage prevention portion 100 is reduced even if the pressing pressure Ps increases during the material intake period. Meanwhile, during periods other than the material intake period, the material to be kneaded is less likely to leak even if the pressing pressure Ps is lower than during the material intake period, so the pressing pressure Ps is controlled to be lower than during the material intake period. Accordingly, the lubricant supply rate R is also reduced compared to during the material intake period, thereby reducing the total amount of lubricant supplied during the kneading process.

[0065] Furthermore, when the seal gap S between the fixed side seal member 10 and the rotating side seal member 9 becomes equal to or greater than a predetermined value Sth, an alarm is issued from the alarm 36, thereby detecting signs of leakage of the material to be kneaded. Furthermore, when the seal gap S becomes equal to or greater than the predetermined value Sth, the pressing pressure Ps is further increased, so that when signs of leakage of the material to be kneaded are detected, the pressing pressure Ps can be further increased to suppress leakage of the material to be kneaded. At this time, if the amount of lubricating oil supplied is further increased, leakage of the material to be kneaded can be further suppressed.

[0066] [Variations] In the above embodiment, the pressing mechanism 48 oscillates the yoke 20 using the hydraulic cylinder 23, but this is not necessarily limited to the hydraulic cylinder 23. For example, the pressing mechanism 48 may use a pneumatic cylinder instead of the hydraulic cylinder 23. Furthermore, a device other than a cylinder may be used as the mechanism for oscillating the yoke 20, such as oscillating the yoke 20 via a ball screw or by using a spring.

[0067] Furthermore, in the above embodiment, the pressing mechanism 48 presses the fixed-side seal member 10 against the rotating-side seal member 9 via the yoke 20, but the present invention does not necessarily require the yoke 20. Specifically, the pressing mechanism 48 may be configured to directly press the fixed-side seal member 10 using a hydraulic cylinder (or pneumatic cylinder), a ball screw, a spring, or the like.

[0068] In the above embodiment, the yoke 20 presses the fixed-side seal member 10 at two points via the yoke pin 21, but the number of points at which the fixed-side seal member 10 is pressed is not limited to two. For example, the yoke 20 may be configured to press the fixed-side seal member 10 at three points.

[0069] In addition, in the above embodiment, three oil filler ports 18A are formed in the fixed-side seal member 10, but the number of oil filler ports 18A is not limited to this. For example, two oil filler ports 18A may be formed near the yoke pin 21 of the yoke 20, or four or more oil filler ports 18A may be formed.

[0070] In the above embodiment, the pressing pressure Ps is feedback-controlled based on the deviation between the seal gap S and the predetermined value Sth during the material intake period, but the present invention is not necessarily limited to this. For example, a relationship map of the pressing pressure Ps versus the seal gap S may be stored in advance, and the pressing pressure Ps may be determined by referring to the relationship map during the material intake period.

[0071] Furthermore, in the above embodiment, the weight 5 is temporarily raised to the upper limit position Phi in period C, but it is not necessarily required to raise it to the upper limit position Phi, and a process other than periods A to E may be added. Also, in the above embodiment, the pressing pressure Ps and the lubricant supply amount R are set to the same values ​​in periods D and E as shown in Fig. 5, but they may be changed to values ​​appropriate for each period. [Explanation of symbols]

[0072] 1: Mixer (internal mixer) 2: Kneading rotor 2A: Rotor shaft 2B: Mixing blade section 3: Casing 4: Chamber 5: Weight 9: Rotating side seal member 10: Fixed side seal member 18A: Oil filler port 21: Yoke pin (pressing part) 34: Eddy current sensor (seal gap measurement section) 36: Alarm (material leak warning unit) 48: Pressing mechanism (seal pressure mechanism) 50: Lubricating oil supply mechanism 100:Leakage prevention part

Claims

1. a casing having a chamber therein for accommodating an object to be kneaded; a kneading rotor including a rotor shaft portion extending outside the chamber and a kneading blade portion disposed inside the chamber, the kneading rotor rotating to knead the material to be kneaded in the chamber; a weight that is provided in the casing so as to be able to rise and fall and that pushes the material to be mixed that has been introduced into the chamber; a leakage prevention part that prevents the material to be kneaded in the chamber from leaking to the outside of the chamber; a lubricating oil supply mechanism that supplies lubricating oil to the leakage prevention section, the leakage prevention unit includes a fixed-side seal member attached to the casing so as to surround the rotor shaft, and a rotating-side seal member attached to the rotor shaft so as to face the fixed-side seal member and rotatable while sliding relative to the fixed-side seal member, The lubricating oil supply mechanism increases the amount of lubricating oil supplied to the leakage prevention section during a material intake period in which the material to be kneaded is taken into the chamber.

2. 2. The internal mixer according to claim 1, further comprising a seal pressurizing mechanism that increases the pressure applied between the fixed-side seal member and the rotating-side seal member during the material intake period.

3. 3. The internal mixer according to claim 1, wherein the material intake period includes at least a part of a period during which the weight pushes the material to be mixed after the material to be mixed is introduced into the chamber until the weight reaches a predetermined lower limit position.

4. 3. The internal mixer according to claim 1, further comprising: a seal gap measuring unit that measures a seal gap between the fixed side seal member and the rotating side seal member; and a material leakage warning unit that issues a warning when the seal gap measured by the seal gap measuring unit becomes equal to or greater than a predetermined value.

5. a seal gap measuring unit for measuring a seal gap between the stationary seal member and the rotating seal member; 3. The internal mixer according to claim 2, wherein when the seal gap measured by the seal gap measuring unit reaches or exceeds a predetermined value, the seal pressurizing mechanism further increases the pressure applied between the fixed side seal member and the rotating side seal member.

6. the seal pressure mechanism has a pressing portion that presses the stationary seal member against the rotating seal member, the lubricating oil supply mechanism has an oil inlet that penetrates the stationary-side seal member and supplies lubricating oil between the stationary-side seal member and the rotating-side seal member, 3. The internal mixer according to claim 2, wherein the oil inlet is formed in the vicinity of a portion of the stationary seal member that is pressed by the pressing portion.

Images