Method and system for kneading rubber material

Abstract

To provide a method and system for kneading rubber materials that can efficiently produce kneaded rubber of target quality by using a closed-type kneader.SOLUTION: While a pair of rotors 3, 3 are rotating, one batch of rubber material R is supplied to a kneader 2 by supply means 9 and poured into the kneader 2 through a hopper 6. In this step, a control device 10 performs supply interruption control to temporarily stop a supply of the rubber material R to the kneader 2 by the supply means 9 for a predetermined period of time, or supply reduction control to reduce a supply speed V of the rubber material R to the kneader 2 by the supply means 9. After one batch of rubber material R has been poured into the kneader 2, a ram 5 is moved downward to a lower limit position P to block a top of a kneading chamber 4a, and the rubber material R is kneaded by the rotating pair of rotors 3, 3.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a kneading method and system for rubber materials, and more particularly to a kneading method and system for rubber materials capable of efficiently producing kneaded rubber of target quality using a closed kneader.

Background Art

[0002] In the production of rubber products such as tires and rubber hoses, unvulcanized kneaded rubber is used. This kneaded rubber is produced, for example, using a closed kneader called a Banbury mixer. Rubber materials containing raw rubber and various compounding agents are charged into this kneader, and one batch of rubber material is kneaded by a pair of left and right rotors installed in the kneading chamber (see, for example, Patent Document 1).

[0003] In this kneading process for producing kneaded rubber, the rubber material is repeatedly passed between a pair of rotors rotating in opposite directions, and a shearing force is applied to the rubber material between each rotor and the inner wall of the kneading chamber while dispersing each compounding agent. In order to obtain kneaded rubber of target quality in which the compounding agents are evenly dispersed and have an appropriate viscosity, it is necessary to knead the rubber material by a pair of rotors for a predetermined time.

[0004] By the way, the rubber material charged into the kneader may not enter or may have difficulty entering between the pair of rotors. In this case, the rubber material stays on the pair of rotors. When the amount of this retention of the rubber material becomes excessive, the entire amount of one batch of rubber material cannot be smoothly charged into the kneader. Along with this, the time for the entire kneading process becomes longer, and the production efficiency of kneaded rubber of target quality decreases. Therefore, there is room for improvement in efficiently producing kneaded rubber of target quality using a closed kneader.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a kneading method and a system for rubber materials capable of efficiently producing kneaded rubber of a target quality using a closed kneader.

Means for Solving the Problems

[0007] In the kneading method of the rubber material of the present invention for achieving the above object, a batch of rubber material is charged into a closed kneader through a hopper, and a ram disposed above the kneading chamber of the kneader is moved downward to a predetermined lower limit position to close the upper part of the kneading chamber, and in the kneading method of the rubber material in which a pair of left and right rotors are rotated in opposite directions to each other inside the kneading chamber to knead the rubber material, while rotating the pair of rotors, during the process of charging a batch of the rubber material into the kneader, supply interruption control for temporarily stopping the supply of the rubber material to the kneader for a predetermined time, or supply reduction control for reducing the supply rate of the rubber material to the kneader is performed.

[0008] The kneading system of the rubber material of the present invention includes a closed kneader having a pair of left and right rotors rotating in opposite directions inside a kneading chamber, a hopper installed above the kneading chamber, and a ram moving up and down above the kneading chamber, a supply means for supplying the kneader with a batch of rubber material, and a control device. In the rubber material kneading system in which the ram is moved downward to a predetermined lower limit position to close the upper part of the kneading chamber and the rubber material is kneaded by the pair of rotating rotors, while rotating the pair of rotors, when a batch of the rubber material is being supplied to the kneader by the supply means and is being put into the kneader through the hopper, the control device performs supply interruption control for temporarily stopping the supply of the rubber material to the kneader by the supply means for a predetermined time, or supply reduction control for reducing the supply speed of the rubber material to the kneader by the supply means.

Effect of the Invention

[0009] According to the present invention, while rotating the pair of rotors, by performing the supply interruption control or the supply reduction control while a batch of the rubber material is being put into the kneader through the hopper, it is possible to avoid an excessive amount of the rubber material staying on the pair of rotors without the rubber material entering between the pair of rotors. Along with this, it is advantageous for smoothly putting the entire amount of a batch of rubber material into the kneader. As a result, it is possible to avoid an increase in the time of the entire kneading process and efficiently manufacture kneaded rubber of a target quality.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the rubber material kneading method and system of the present invention will be described based on the embodiments shown in the drawings.

[0012] In the embodiment of the rubber material kneading system 1 illustrated in FIGS. 1 to 3, the rubber material R is kneaded batch by batch to produce an unvulcanized kneaded rubber Rn of a predetermined quality. In this embodiment, a rubber material R formed in a sheet shape by kneading the raw rubber and various compounding agents at once is used. As the compounding agent, there may be a case where the rubber material R contains a non-vulcanizing compounding agent and does not contain a vulcanizing compounding agent, and there may also be a case where the rubber material R contains both a non-vulcanizing compounding agent and a vulcanizing compounding agent.

[0013] As the raw rubber, various known rubber types such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), 1,2-polybutadiene, chloroprene rubber, butyl rubber, styrene-butadiene rubber (SBR), nitrile rubber (acrylonitrile rubber, hydrogenated nitrile rubber), ethylene propylene diene rubber, etc. are used. The raw rubber is used alone or in combination of two or more kinds. As the non-vulcanized compounding agents, for example, appropriate ones among various known compounding agents such as carbon black, silica, silane coupling agent, zinc oxide, stearic acid, etc. are used as necessary. As the vulcanized compounding agents, for example, appropriate ones among known compounding agents such as sulfur, vulcanization accelerator, vulcanization accelerator assistant, vulcanization retarder, etc. are used as necessary.

[0014] This kneading system 1 includes a closed kneader 2 (hereinafter referred to as the kneader 2), a supply means 9 for supplying the rubber material R for one batch to the kneader 2, and a control device 10. The control device 10 controls the operations of the kneader 2 and the supply means 9. A known computer is used as the control device 10.

[0015] The kneader 2 is a so-called Banbury mixer, and various known types can be used. This kneader 2 has a kneading chamber 4a, a ram chamber 4b connected to the upper end opening of the kneading chamber 4a and extending upward, a pair of left and right rotors 3, 3 arranged inside the kneading chamber 4a, and a ram 5 arranged to be movable up and down in the ram chamber 4b. In the drawing, the position (lower limit position P) of the boundary between the kneading chamber 4a and the ram chamber 4b is shown by a dashed line. An opening and closing discharge door 8 is provided on the bottom surface of the kneading chamber 4a. A hopper 6 is installed on the side surface of the ram chamber 4b.

[0016] Each rotor 3, 3 has a rotor shaft 3a and stirring blades 3b protruding from the rotor shaft 3a. Each rotor 3, 3 (rotor shafts 3a, 3a) is arranged opposite and parallel to each other, and each rotor shaft 3a, 3a is connected to a drive motor via a speed changer. Each rotor 3, 3 is rotationally driven in opposite directions to each other by the drive motor. The rotational drive, stop, and rotational speed of the rotors 3, 3 are controlled by the control device 10. In this embodiment, meshing rotors 3, 3 are used, but non-meshing rotors 3, 3 can also be used.

[0017] The ram 5 is moved up and down by a lifting mechanism such as a hydraulic cylinder. The vertical movement (vertical position) of the ram 5 is controlled by the control device 10. When the ram 5 in the standby position illustrated in FIG. 1 moves downward to the lower limit position P and closes the upper end opening of the kneading chamber 4a as illustrated in FIG. 3, the kneading chamber 4a is brought into a predetermined sealed state. The ram 5 applies a ram pressure to the rubber material R inside the kneading chamber 4a. In the kneading process, the ram pressure is adjusted by appropriately moving the ram 5 up and down.

[0018] The hopper 6 includes a cover 6a that covers a supply port formed on the side surface of the ram chamber 4b, and an opening / closing mechanism 7 that moves the cover 6a to open and close the supply port. The movement of the opening / closing mechanism 7 is controlled by the control device 10. The opening and closing of the discharge door 8 are also controlled by the control device 10.

[0019] As the supply means 9, a known conveyor or the like can be used. One end of the supply means 9 is located above the hopper 6. One batch of the rubber material R is placed on the supply means 9. By operating the supply means 9, the placed rubber material R is conveyed toward the hopper 6 and sequentially charged into the kneading chamber 4a through a supply port formed on the side surface of the ram chamber 4b. That is, one batch of the rubber material R is continuously supplied and charged to the kneading machine 2 through the hopper 6 by the supply means 9.

[0020] After one batch of rubber material R is charged into the kneader 2, as illustrated in FIG. 3, the ram 5 that was in the standby position is moved downward to the lower limit position P to close the upper part of the kneading chamber 4a. The supply port formed on the side surface of the ram chamber 4b is closed by the cover 6a. Inside the kneading chamber 4a, the rubber material R is kneaded for a predetermined kneading time set by a pair of rotors 3, 3 that rotate in opposite directions to each other, and kneaded rubber Rn of the target quality is produced.

[0021] Next, an example of the procedure for kneading the rubber material using this kneading system 1 to produce kneaded rubber Rn of the target quality will be described.

[0022] As illustrated in FIG. 4, while rotating a pair of rotors 3, 3, one batch of rubber material R is sequentially charged into the kneader 2. The rotors 3, 3 will continue to rotate at substantially the same rotational speed until the kneading process is completed. The rubber material R is conveyed toward the kneader 2 by the supply means 9. The conveying speed (supply speed) of the rubber material R is set to a constant speed V.

[0023] The conveyed rubber material R is dropped into the hopper 6 and is charged into the kneading chamber 4a (above the rotor 3) from the supply port on the side surface of the ram chamber 4b. More specifically, one sheet-like rubber material R is continuously stacked and placed on the supply means 9. Sequentially from the tip side of this sheet-like rubber material R, it is charged into the kneading chamber 4a (above the rotor 3) through the hopper 6.

[0024] When a part of the charged rubber material R enters between the pair of rotors 3, 3 and is bitten by the rotating rotors 3, 3, the subsequent rubber material R is also bitten by the rotating rotors 3, 3 due to being dragged by it. As a result, the rubber material R sequentially passes downward between the rotating rotors 3, 3 and then returns above the pair of rotors 3, 3.

[0025] After one batch of rubber material R is fed into the kneader 2, as illustrated in FIG. 3, inside the kneading chamber 4a, a kneading cycle in which the rubber material R passes downward between a pair of rotors 3, 3 rotating in opposite directions to each other and then returns upward is repeated. In this kneading cycle, a shearing force is applied to the rubber material R between each rotor 3, 3 and the inner wall of the kneading chamber 4a to reduce the viscosity, and in the rubber material R, each compounding agent is dispersed. By performing this kneading cycle for a set predetermined kneading time, the compounding agents are evenly dispersed and kneaded rubber Rn of a target quality with an appropriate viscosity is produced.

[0026] However, in the process of feeding the rubber material R into the kneader 2, if the rubber material R does not enter between the pair of rotors 3, 3 and is not bitten by the rotating rotors 3, 3, the rubber material R will stay on top of the pair of rotors 3, 3. When an excessive amount of the rubber material R stays on the pair of rotors 3, 3, it becomes impossible to smoothly feed the entire amount of the rubber material R for one batch into the kneader 2.

[0027] Therefore, as illustrated in FIG. 5, while the rubber material R is being sequentially fed into the kneader 2, the operation of the feeding means 9 is stopped (feeding speed V = 0), and the conveyance of the rubber material R by the feeding means 9 is temporarily stopped for a predetermined time t. That is, supply interruption control is performed to temporarily stop the supply of the rubber material R to the kneader 2 for a predetermined time t. Thereby, it is possible to avoid an excessive amount of the rubber material R staying on top of the pair of rotors 3, 3 in a state where the rubber material R does not enter between the pair of rotors 3, 3. Since it becomes possible to make a part of the rubber material R be bitten by the pair of rotors 3, 3 while this supply interruption control is being performed, it is advantageous for smoothly feeding the entire amount of the rubber material R for one batch into the kneader 2. After the elapse of the predetermined time t, the operation of the feeding means 9 is restarted, and the remaining amount of the rubber material R is sequentially fed into the kneader 2.

[0028] For example, as the predetermined time t, the supply of the rubber material R is stopped for about several seconds to 10 seconds, more preferably about 2 seconds to 5 seconds. Since the optimum value of this predetermined time t varies depending on the type of the rubber material R, the specifications of the kneader 2, etc., a preliminary test or the like is performed to grasp the optimum value. Then, in this production, the supply of the rubber material R to the kneader 2 may be temporarily stopped for the predetermined time t of the optimum value grasped in advance. If this predetermined time t is too long, it will lead to a decrease in the production efficiency of the kneaded rubber Rn, so it should be set as short as possible.

[0029] Alternatively, instead of the above-described supply interruption control, while the rubber material R is being sequentially charged into the kneader 2, as illustrated in FIG. 6, the supply speed of the rubber material R by the supply means 9 is reduced from the speed V to the speed V1 (speed V > speed V1). That is, supply reduction control for reducing the supply speed of the rubber material R to the kneader 2 is performed. Also by this supply reduction control, it is possible to avoid an excessive amount of the rubber material R staying on the pair of rotors 3, 3 without the rubber material R entering between the pair of rotors 3, 3.

[0030] In the supply reduction control, for example, the supply speed V1 is reduced to 10% - 20% of the supply speed V. After maintaining this reduced supply speed V1 for about 5 seconds to 10 seconds to temporarily reduce the supply amount of the rubber material R to the kneader 2, the original supply speed V is restored and the remaining amount of the rubber material R is charged into the kneader 2. Since the optimum value of the maintenance time T of this reduced supply speed V1 varies depending on the type of the rubber material R, the specifications of the kneader 2, etc., a preliminary test or the like is performed to grasp the optimum value. Then, in this production, the maintenance time T of the reduced supply speed V1 of the rubber material R to the kneader 2 may be set to the optimum value grasped in advance. If this maintenance time T is too long, it will lead to a decrease in the production efficiency of the kneaded rubber Rn, so it should be set as short as possible.

[0031] When the kneading process of one batch of the rubber material R is completed, the discharge door 8 is opened to discharge the kneaded rubber Rn from the bottom surface of the kneading chamber 4a. Subsequently, the same kneading process is performed on a new batch of the rubber material R to produce the kneaded rubber Rn for the required number of batches.

[0032] When the supply interruption control or supply reduction control described above is performed, the time required for the control (predetermined time t or maintenance time T) is added to the kneading process. However, it is advantageous that a large amount of rubber material R does not stay on the pair of rotors 3, 3 without waste, and the entire amount of the rubber material R for one batch can be smoothly fed into the kneader 2. That is, by performing the supply interruption control or supply reduction control, the amount of the rubber material R staying on the pair of rotors 3, 3 is optimized in the process of feeding the rubber material R into the kneader 2, and it becomes easier to smoothly feed the entire amount of the rubber material R for one batch into the kneader 2. As a result, it becomes possible to sufficiently knead the rubber material R for one batch with the set predetermined process time without increasing the time required for the entire process, and to produce the kneaded rubber Rn of the target quality.

[0033] When the rubber material R is in a sheet shape, in the process of feeding the rubber material R into the kneader 2, due to phenomena such as the rubber material R adhering to or getting caught on the hopper 6 and the cover 6a, the entire amount of the rubber material R for one batch may not be smoothly fed into the kneading chamber 4a. In such a case, the ram 5 that has been moved downward often does not descend to the lower limit position P. Whether the ram 5 has descended to the lower limit position P can be detected using a known sensor.

[0034] Therefore, after feeding the rubber material R for one batch into the kneader 2, when the ram 5 is moved downward as illustrated in FIG. 7 and the ram 5 does not descend to the lower limit position P, as illustrated in FIG. 8, the ram 5 is moved upward to the standby position. Then, the cover 6a of the hopper 6 is opened and closed a plurality of times to eliminate the adhesion and snagging of the rubber material R to and on the hopper 6 and the cover 6a.

[0035] After that, the ram 5 is moved downward again. When the ram 5 descends to the lower limit position P as a result, the rubber material R is kneaded to produce the kneaded rubber Rn. On the other hand, when the ram 5 does not descend to the lower limit position P, it is presumed that the adhesion and snagging of the rubber material R to and on the hopper 6 and the cover 6a have not been eliminated. Therefore, the kneading process of the rubber material R is stopped. And after taking appropriate measures, the kneading process is restarted.

[0036] In the above-described embodiment, a sheet-like rubber material R is kneaded. However, the present invention can also be applied when a block-shaped raw rubber (so-called bale rubber) is put into the kneader 2 and kneaded as the rubber material R.

Explanation of Reference Numerals

[0037] 1 Kneading system 2 Sealed kneader 3 Rotor 3a Rotor shaft 3b Agitating blade 4a Kneading chamber 4b Ram chamber 5 Ram 6 Hopper 6a Cover 7 Opening / closing mechanism 8 Discharge door 9 Feeding means (conveyor) 10 Control device R Rubber material Rn Kneaded rubber

Claims

1. In a method for kneading a rubber material, a batch of rubber material is charged into a closed kneader through a hopper, a ram disposed above the kneading chamber of the kneader is moved downward to a predetermined lower limit position to close the upper part of the kneading chamber, and a pair of left and right rotors inside the kneading chamber are rotated in opposite directions to knead the rubber material. During the process of charging a batch of the rubber material into the kneader while rotating the pair of rotors, a supply interruption control for temporarily stopping the supply of the rubber material to the kneader for a predetermined time, or a supply reduction control for reducing the supply rate of the rubber material to the kneader is performed.

2. The method for kneading a rubber material according to Claim 1, wherein the supply interruption control is performed.

3. The method for kneading a rubber material according to Claim 1 or 2, wherein the rubber material is in a sheet shape.

4. After charging a batch of the rubber material into the kneader, when the ram moved downward does not descend to the lower limit position, the ram is moved upward and the opening and closing operation of the hopper is performed a plurality of times. Then, when the ram is moved downward again and descends to the lower limit position, the rubber material is kneaded, and when it does not descend to the lower limit position, the kneading of the rubber material is stopped. The method for kneading a rubber material according to Claim 3.

5. A closed kneader having a pair of left and right rotors rotating in opposite directions inside the kneading chamber, a hopper installed above the kneading chamber, and a ram moving up and down above the kneading chamber, a supply means for supplying a batch of rubber material to the kneader, and a control device. In a rubber material kneading system in which the ram is moved downward to a predetermined lower limit position to close the upper part of the kneading chamber, and the rubber material is kneaded by the pair of rotating rotors. During the process of supplying a batch of the rubber material to the kneader by the supply means through the hopper while rotating the pair of rotors, the control device performs a supply interruption control for temporarily stopping the supply of the rubber material to the kneader by the supply means for a predetermined time, or a supply reduction control for reducing the supply rate of the rubber material to the kneader by the supply means.

Images