Kneading Machine

Abstract

To provide a kneader which suppresses productivity degradation of rubber material forming and quality degradation of a rubber material resulting from fall of a residue after kneading from a pressure lid.SOLUTION: A kneader comprises: a rotatable mixing tank 2 which houses a rubber composition in housing posture where an opening 2a opens in an upward direction, and discharges a rubber material in discharging posture where the opening 2a opens in a downward direction; a pressure lid 3 which enters into the mixing tank 2 in the housing posture, pressurizes the rubber composition, and leaves after kneading; a shaft member 4 which kneads the rubber composition in the mixing tank 2 by a rotating blade; and a plate member which stands by at a standby position while the pressure lid 3 is entering into the mixing tank 2, moves to an interposed position between the mixing tank 2 and the pressure lid 3 before the mixing tank 2 rotates from the housing posture to the discharging posture after the pressure lid 3 leaves from the mixing tank 2, and is interposed between the mixing tank 2 and the pressure lid 3 at the interposed position until the mixing tank 2 rotates from the housing posture to the discharging posture, discharges the rubber material, rotates again, and returns to the housing posture.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a kneader for kneading a rubber composition to form a rubber dough. [Background technology]

[0002] Rubber products are generally manufactured by adding various additives for forming rubber mass, such as carbon black, silica, plasticizers, etc., to rubber raw materials such as natural rubber or synthetic rubber, kneading the mixture to form a rubber mass, and then molding / curing the rubber mass into a predetermined shape. As a device for kneading a rubber composition obtained by adding additives for forming rubber mass to a rubber raw material in this way, kneaders for forming rubber mass have been conventionally known (see, for example, Patent Documents 1 and 2). Here, an example of a conventional kneader will be briefly described.

[0003] FIG. 1 is a schematic diagram showing a conventional kneading machine 1' (more precisely, a part of it) from the side for kneading a rubber composition to form a rubber dough.

[0004] A conventional kneader 1' shown in Fig. 1 has a mixing tank 2 that contains a rubber composition, a pressurizing lid 3 that pressurizes the contained rubber composition, and a shaft member 4 that kneads the pressurized rubber composition. The shaft member 4 has blades 4a on its peripheral surface and rotates around a central axis 4b. As the shaft member 4 rotates, the blades 4a rotate and the rubber composition is agitated, thereby kneading the rubber composition and forming a rubber dough.

[0005] FIG. 2 is a schematic diagram showing how a rubber mass formed by kneading a rubber composition is discharged.

[0006] When the rubber composition is sufficiently mixed to form a rubber dough, the pressure lid 3 is withdrawn upward from the mixing tank 2, and after the pressure lid 3 is withdrawn, the mixing tank 2 rotates as shown in FIG. 2, and the rubber dough in the mixing tank 2 is discharged toward a specified rubber dough storage container (not shown). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2006-289233 A [Patent Document 2] Patent No. 6444683 specification Summary of the Invention [Problem to be solved by the invention]

[0008] However, residues R, such as rubber composition (e.g., plasticizer) that was not kneaded and rubber dough that was not discharged after kneading, may adhere to the surface of the pressurizing lid 3 that was pressing the rubber composition. Such residues R may fall toward the rotating mixing tank 2 as shown in FIG. 2 and soil the outer surface of the mixing tank 2 and the surroundings of the mixing tank 2. In this case, cleaning may be required, which may reduce the productivity of rubber dough formation. Furthermore, if the residues R are rubber composition that was not kneaded and remains, they may be mixed into the rubber dough being discharged, resulting in a decrease in the quality of the rubber dough.

[0009] In view of the above circumstances, the present invention aims to realize a kneading machine that suppresses the decrease in productivity in rubber dough formation and the deterioration of the quality of the rubber dough caused by the falling of residue after kneading from the pressure lid. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the present invention provides the following kneader.

[0011] [1] A kneader for kneading a rubber composition to form a rubber dough, comprising: a mixing tank having an opening and capable of switching an opening direction of the opening between a predetermined upward direction and a predetermined downward direction by rotating, the mixing tank storing the rubber composition in a storing position in which the opening opens in the predetermined upward direction, and discharging a rubber dough formed by kneading the rubber composition in a discharging position in which the opening opens in the predetermined downward direction; a pressurizing lid which, with respect to the mixing tank in the storing position, enters the mixing tank through the opening from a direction opposite to the predetermined upward direction to pressurize the rubber composition stored in the mixing tank, and after kneading the rubber composition, exits the mixing tank through the opening in the predetermined upward direction; and a shaft member which is provided in the mixing tank, has a blade on its peripheral surface protruding in a direction away from a central axis, and rotates around the central axis, the shaft member being stored in the mixing tank and pressurized by the pressurizing lid. a shaft member that mixes the rubber composition with the rotating blade to knead the rubber composition and form the rubber dough; and a plate-like member that extends within a plane intersecting the predetermined upward direction, which waits at a predetermined standby position away from the pressurizing lid and the mixing tank while the pressurizing lid is in the mixing tank, moves within the plane from the standby position toward an interposition position between the mixing tank and the pressurizing lid after the pressurizing lid has left the mixing tank and before the mixing tank rotates from the storage position to the discharge position, and is interposed between the mixing tank and the pressurizing lid at the interposition position until the mixing tank rotates from the storage position to the discharge position to discharge the rubber dough and rotates from the discharge position to return to the storage position after the rubber dough has been discharged, and moves within the plane from the interposition position toward the standby position after the mixing tank has rotated from the discharge position to return to the storage position.

[0012] [2] The kneader according to [1], further comprising a stand for supporting the plate-like member at the standby position.

[0013] [3] A kneader as described in [1] or [2], comprising: a cylindrical housing portion; a rod whose tip is fixed to the plate-like member and can be freely inserted and removed from the housing portion; and an air cylinder that moves the plate-like member between the standby position and the interposition position by inserting and removing the rod.

[0014] [4] The kneader described in [3], wherein the plate-shaped member reaches the interposition position when the rod is extended to its maximum extent from the housing portion, and further comprising a first sensor that detects when the rod is extended to its maximum extent from the housing portion, and wherein the mixing tank rotates from the storage position to the discharge position when the first sensor detects that the rod has been extended to its maximum extent from the housing portion.

[0015] [5] The kneader described in [3] or [4], wherein the plate-shaped member reaches the standby position when the rod is inserted to its maximum extent into the housing portion, and further comprising a second sensor that detects that the rod has been inserted to its maximum extent into the housing portion, and wherein the pressurizing lid begins to move toward the mixing tank to re-enter the mixing tank when the second sensor detects that the rod has been inserted to its maximum extent into the housing portion. Effect of the Invention

[0016] In the kneader of the present invention, by interposing a plate-like member between the mixing tank and the pressurizing lid after kneading, the residue that has fallen from the pressurizing lid is prevented from reaching the vicinity of the mixing tank during the rubber material discharge. As a result, in the present invention, it is possible to suppress a decrease in productivity of rubber material formation and a decrease in the quality of the rubber material caused by the falling of the residue. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a conventional kneading machine (more precisely, a part of the machine) from the side for kneading a rubber composition to form a rubber dough. [Diagram 2] FIG. 2 is a schematic diagram showing a state in which a rubber mass formed by kneading a rubber composition is discharged. [Diagram 3] 1 is a schematic configuration diagram showing the configuration of a kneader according to one embodiment of the present invention from the front. [Figure 4] FIG. 2 is a front view showing a schematic state of the mixer after the pressurizing lid has been withdrawn from the mixing vessel and before the mixing vessel has been rotated from the containing position to the discharging position. [Diagram 5] FIG. 5 is a front view showing a schematic view of the mixer when the mixing vessel starts to rotate from the accommodation position shown in FIGS. 3 and 4 toward the discharge position. [Figure 6] FIG. 1 is a schematic side view of a kneader (or, more precisely, a part of the kneader) in a discharging position discharging rubber dough. [Figure 7] 7 is a front view showing a schematic view of the mixer after the mixing vessel has rotated from the discharge position in FIG. 6 back to the storage position in FIGS. 3 and 4. FIG. [Figure 8] 8 is a front view showing a schematic view of the state of the kneader after the plate-like member in FIG. 7 has reached the standby position in FIG. 3. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be understood that the present invention is not limited to the following embodiment, and that appropriate design changes, improvements, etc. may be made based on the ordinary knowledge of a person skilled in the art without departing from the spirit of the present invention.

[0019] In the following explanation, the term "rubber composition" refers to a material in which various additives for forming rubber mass, such as carbon black, silica, plasticizers, etc., are simply mixed into rubber raw materials such as natural rubber or synthetic rubber, and the composition is not yet uniform. In other words, the "rubber composition" refers to a simple aggregate of multiple types of rubber materials. By kneading such a "rubber composition," a "rubber mass" with a uniform composition is formed.

[0020] FIG. 3 is a schematic configuration diagram showing the configuration of the kneader 1 according to one embodiment of the present invention from the front.

[0021] The kneading machine 1 is an apparatus for kneading a rubber composition to form a rubber dough, and includes a mixing tank 2, a pressurizing lid 3, a shaft member 4, and a plate-like member 5. In Fig. 3, the same components as those in Fig. 1 are denoted by the same reference numerals.

[0022] The mixing tank 2 has an opening 2a, and as described below, the opening direction of the opening 2a can be switched between a predetermined upward direction and a predetermined downward direction by rotating. The mixing tank 2 stores the rubber composition in a storage position where the opening 2a opens in a predetermined upward direction, and discharges the rubber material obtained by kneading the rubber composition in a discharge position where the opening 2a opens in a predetermined downward direction. FIG. 3 shows the mixing tank 2 in the storage position, and the rubber composition is stored in the mixing tank 2. Note that FIG. 3 shows the front view of the mixing tank 2, and FIG. 1 shows the side view of the mixing tank 2.

[0023] Here, the "predetermined upward direction" means a direction of the opening 2a in which the opening direction of the opening 2a includes a vertically upward component, and the contents (specifically, the rubber composition) contained in the mixing tank 2 are stably held in the mixing tank 2 without flowing out from the opening 2a. Typically, the "predetermined upward direction" is a vertically upward direction as shown in FIG. 3. However, this is merely a typical example, and the "predetermined upward direction" of the present invention may be a diagonally upward direction that satisfies the above definition. On the other hand, the "predetermined downward direction" means a direction of the opening 2a in which the opening direction of the opening 2a includes a vertically downward component, and the contents (specifically, the rubber material) contained in the mixing tank 2 flow out from the opening 2a. The mixing tank 2 when it is in a discharge position in which the opening 2a is open in a predetermined downward direction will be described later.

[0024] The pressurizing lid 3 is a member that enters the mixing tank 2 in the storage position through the opening 2a from the direction opposite to the above-mentioned predetermined upward direction (vertical upward direction in FIG. 3) and pressurizes the rubber composition stored in the mixing tank 2. As will be described later, after the rubber composition is kneaded, the pressurizing lid 3 exits the mixing tank through the opening 2a in the above-mentioned predetermined upward direction (vertical upward direction in FIG. 3). Here, FIG. 3 shows the front view of the pressurizing lid 3 that has entered the mixing tank 2 and is pressurizing the rubber composition in the mixing tank 2, and the above-mentioned FIG. 1 shows the side view of the pressurizing lid 3.

[0025] The shaft member 4 is provided in the mixing tank 2, has a blade 4a on its circumferential surface protruding in a direction away from the central axis 4b, and is a member that rotates around the central axis 4b. The shaft member 4 kneads the rubber composition contained in the mixing tank 2 and pressurized by the pressure lid 3 by stirring the rubber composition with the rotating blade 4a to form a rubber dough. Here, Fig. 3 shows the front view of the shaft member 4, and the shaft member 4 shown in Fig. 3 is the front shaft member 4 of the two shaft members 4 whose side is shown in Fig. 1.

[0026] The plate-like member 5 is a plate-like member that extends in a plane that intersects with the above-mentioned predetermined upward direction (the vertically upward direction in FIG. 3). The plate-like member 5 waits at a predetermined standby position away from the pressurizing lid 3 and the mixing tank while the pressurizing lid 3 is in the mixing tank 2. FIG. 3 shows the plate-like member 5 when it waits at the predetermined standby position, and the above-mentioned plane is a plane along the plate-like member 5 that is positioned at the predetermined standby position.

[0027] In the kneader 1, as shown in Fig. 3, the pressure lid 3 enters the mixing tank 2 and pressurizes the rubber composition contained in the mixing tank 2 while the shaft member 4 kneads the rubber composition, and a rubber dough is formed by this kneading. When the kneading is performed sufficiently to form the rubber dough, the rotation of the shaft member 4 stops, and the pressure lid 3 exits the mixing tank 2 through the opening 2a. Whether or not the kneading is performed sufficiently can be determined, for example, by whether or not the number of rotations of the shaft member 4 exceeds a predetermined threshold number of times, or whether or not the duration of the kneading by the rotation of the shaft member 4 exceeds a predetermined threshold time.

[0028] FIG. 4 is a schematic front view of the mixer 1 after the pressurizing lid 3 has been withdrawn from the mixing vessel 2 and before the mixing vessel 2 has rotated from the containing position to the discharging position.

[0029] When the pressurizing lid 3 withdraws from the mixing tank 2 and moves vertically upward in the direction of the dotted arrow in Fig. 4, away from the mixing tank 2, the plate-like member 5 moves in the direction of the thick arrow in Fig. 4 from the standby position in Fig. 3 within the above-mentioned plane toward the interposition position between the mixing tank 2 and the pressurizing lid 3, as shown in Fig. 4. When the plate-like member 5 reaches the interposition position, the mixing tank 2 rotates from the storage position in Fig. 3 and Fig. 4 to the discharge position.

[0030] FIG. 5 is a schematic front view of the mixer 1 when the mixing tank 2 starts to rotate from the storage position shown in FIGS. 3 and 4 toward the discharge position, and FIG. 6 is a schematic side view of the mixer 1 (or more precisely, a part of it) when the mixer 1 in the discharge position is discharging the rubber dough.

[0031] FIG. 6 shows only the mixing tank 2, the pressurizing lid 3, the shaft member 4, and the plate-like member 5 of the kneader 1 shown in FIG. 5 as viewed from the front side, and shows their side views.

[0032] As shown in Fig. 5, when the mixing tank 2 starts to rotate in the direction of the thick arrow in Fig. 5 from the storage position in Fig. 3 and Fig. 4 to the discharge position in Fig. 6, the plate-like member 5 is already located at the interposition position between the mixing tank 2 and the pressurizing lid 3. Then, as shown in Fig. 6, while the kneader 1 in the discharge position is discharging the rubber dough, the plate-like member 5 is interposed between the mixing tank 2 and the pressurizing lid 3 at this interposition position. This state in which the plate-like member 5 is interposed between the mixing tank 2 and the pressurizing lid 3 continues until the mixing tank 2 rotates from the discharge position in Fig. 6 after discharging the rubber dough and returns to the storage position in Fig. 3. Therefore, the mixing tank 2 is interposed between the mixing tank 2 and the pressurizing lid 3 at the interposition position while the mixing tank 2 rotates from the storage position in Fig. 3 and Fig. 4 to the discharge position in Fig. 6 to discharge the rubber dough, and rotates from the discharge position in Fig. 6 after discharging the rubber dough and returns to the storage position in Fig. 3 and Fig. 4.

[0033] In this manner, in the kneader 1 of the present embodiment, by interposing the plate-like member 5 between the mixing tank 2 and the pressurizing lid 3 after kneading, the residue R that has fallen from the pressurizing lid 3 is prevented from reaching the vicinity of the mixing tank 2 during the rubber dough discharge. As a result, in the kneader 1, it is possible to suppress a decrease in productivity in rubber dough formation and a decrease in the quality of the rubber dough caused by the falling of the residue R.

[0034] FIG. 7 is a schematic front view of the mixer 1 after the mixing vessel 2 has rotated from the discharge position in FIG. 6 back to the storage position in FIGS.

[0035] When the mixing tank 2 rotates from the discharge position in FIG. 6 to return to the storage position in FIGS. 3 and 4, as shown in FIG. 7, the plate-like member 5 moves in the above-mentioned plane in the direction of the thick arrow in FIG. 7 from the intervening position in FIGS. 4 to 6 toward the standby position in FIG. 3.

[0036] FIG. 8 is a schematic front view of the mixer 1 after the plate member 5 in FIG. 7 has reached the standby position in FIG.

[0037] When the plate-like member 5 in Fig. 7 reaches the standby position in Fig. 3, the pressurizing lid 3 moves in the direction of the dotted arrow in Fig. 8 toward the mixing tank 2, as shown in Fig. 8. At the same time, a new rubber composition is supplied to the mixing tank 2, and is kneaded by the rotating shaft member 4 while being pressurized by the pressurizing lid 3 that has entered the mixing tank 2.

[0038] The above is a description of the components of the kneader 1, that is, the mixing tank 2, the pressurizing lid 3, the shaft member 4, and the plate-like member 5. The other components will be described below.

[0039] As shown in Figs. 3 to 5, 7 and 8, the kneader 1 of the present embodiment preferably includes a reducer 6 which is interposed between the mixing tank 2 and a rotation drive means (motor or the like) (not shown) and converts the rotation drive force obtained from the rotation drive means into a rotation drive force having a reduced rotational speed, and supplies the rotation drive force to the mixing tank 2 as the rotation drive force required for switching the position of the mixing tank 2 between the containing position and the discharging position.

[0040] Such a speed reducer 6 allows the attitude of the mixing vessel 2 to be switched between the receiving attitude and the discharging attitude at an appropriate rotation speed and at an appropriate rotation angle.

[0041] In addition, the kneader 1 of this embodiment is preferably provided with a dust cover 7, which is provided above the mixing tank 2 as in the kneader 1 shown in FIG. 3 and surrounds the pressurizing lid 3 as shown in FIGS. 4, 5, 7 and 8 except when the pressurizing lid 3 is inserted into the mixing tank 2 (see FIG. 3).

[0042] By providing such a dust cover 7, it becomes difficult for external dust to get into the mixing tank 2 from around the pressurizing lid 3. Note that, as an example, in Figs. 3 to 5, 7 and 8, the dust cover 7 is shown which moves together with the pressurizing lid 3 when the pressurizing lid 3 moves in a state where it has been removed from the mixing tank 2.

[0043] Other components of the kneader 1 related to the plate-like member 5 will be described below.

[0044] The kneader 1 of this embodiment is preferably provided with a stand 8 that supports the plate-like member 5 at the standby position, like the kneader 1 shown in FIG.

[0045] By providing such a base 8, the posture of the plate-like member 5 at the standby position is stabilized. Note that in Figs. 3 to 5, 7 and 8, the base 8 disposed on the reducer 6 is shown as an example.

[0046] In addition, the kneader 1 of this embodiment preferably includes an air cylinder 9 having a cylindrical housing portion 9a, a rod 9b having a tip portion 90 fixed to the plate-shaped member 5 and capable of being freely inserted and removed from the housing portion 9a, and which moves the plate-shaped member 5 between the standby position of FIG. 3 and the interposition position of FIG. 4 by inserting and removing the rod 9b.

[0047] By providing such an air cylinder 9, it is possible to easily drive the plate-like member 5 between the standby position of FIG. 3 and the interposition position of FIG.

[0048] In addition, in the kneader 1 equipped with the air cylinder 9, the plate-like member 5 reaches the interposition position in Figures 4 and 5 when the rod 9b is extended to its maximum extent from the housing portion 9a, and it is preferable that the kneader 1 is equipped with a first sensor 10 in Figure 5 that detects that the rod 9b has been extended to its maximum extent from the housing portion 9a, and that the mixing tank 2 rotates from the storage position in Figures 3 and 4 to the discharge position in Figure 6 when the first sensor 10 detects that the rod 9b has been extended to its maximum extent from the housing portion 9a.

[0049] By providing such a first sensor 10 and rotating the mixing tank 2, the mixing tank 2 rotates from the containing position to the discharging position after the plate-like member 5 has completely reached the intervening position. As a result, the residue R in Fig. 6 that has fallen from the pressurizing lid 3 is reliably prevented from reaching the vicinity of the mixing tank 2 during the discharging of the rubber material. As such a first sensor 10, for example, a position sensor that detects the position of the end of the rod 9b on the opposite side to the tip 90 within the housing 9a can be used.

[0050] In addition, in the kneader 1 equipped with the air cylinder 9, it is preferable that the plate-like member 5 reaches the standby position in FIG. 8 when the rod 9b is inserted into the housing portion 9a to its maximum extent, that the kneader 1 is equipped with a second sensor 11 in FIG. 8 for detecting that the rod 9b has been inserted into the housing portion 9a to its maximum extent, and that the pressurizing lid 3 starts moving toward the mixing tank 2 to enter the mixing tank 2 again when the second sensor 11 detects that the rod 9b has been inserted into the housing portion 9a to its maximum extent.

[0051] By providing such a second sensor 11, the pressurizing lid 3 moves toward the mixing tank 2 after the plate-like member 5 has completely reached the standby position, thereby preventing the plate-like member 5 from interfering with the pressurizing operation by the pressurizing lid 3.

[0052] Although not shown in Figures 3 to 8, it is preferable to provide a control unit for controlling the operation of each unit described in Figures 3 to 8. By providing such a control unit, the operation of each unit in Figures 3 to 8 is automatically performed.

[0053] The above is a description of this embodiment.

[0054] In the above explanation, an example has been described in which the kneader 1 of this embodiment is applied to kneading a rubber composition to form a rubber dough, but the present invention may also be applied to kneading resin materials to form any resin material other than rubber that has physical properties in common with the rubber dough. [Industrial Applicability]

[0055] INDUSTRIAL APPLICABILITY The present invention is useful for suppressing a decrease in productivity in rubber material formation and a decrease in the quality of the rubber material caused by the dropping of residues after kneading. [Explanation of symbols]

[0056] 1: kneading machine, 2: Mixing tank, 2a: opening, 3: Pressurized lid, 4: Shaft member, 4a: blade, 4b: central axis, 5: plate-shaped member, 6: Reducer, 7: Dust cover, 8: stand, 9: Air cylinder, 9a: Housing part, 9b: Rod, 10: first sensor, 11: second sensor, 90: tip, R:Residue.

Claims

1. In a kneader for kneading a rubber composition to form a rubber dough, a mixing tank having an opening, the opening direction of which can be switched between a predetermined upward direction and a predetermined downward direction by rotating, the mixing tank storing a rubber composition in a storing position in which the opening is open in the predetermined upward direction, and discharging a rubber material obtained by kneading the rubber composition in a discharging position in which the opening is open in the predetermined downward direction; a pressurizing lid which enters the mixing tank in the accommodation position through the opening from a direction opposite to the predetermined upward direction to pressurize the rubber composition accommodated in the mixing tank, and which exits the mixing tank through the opening in the predetermined upward direction after kneading the rubber composition; a shaft member that is provided within the mixing tank and has a blade on its circumferential surface that protrudes in a direction away from a central axis and rotates around the central axis, the shaft member kneading the rubber composition by stirring the rubber composition contained in the mixing tank and pressed by the pressure lid with the rotating blade to form the rubber mass; a plate-like member extending within a plane intersecting the predetermined upward direction, which waits at a predetermined standby position away from the pressurizing lid and the mixing tank while the pressurizing lid is in the mixing tank, moves from the standby position within the plane toward an intervening position between the mixing tank and the pressurizing lid after the pressurizing lid has left the mixing tank and before the mixing tank rotates from the storage position to the discharge position, and is intervening between the mixing tank and the pressurizing lid at the intervening position until the mixing tank rotates from the storage position to the discharge position to discharge the rubber mass and rotates from the discharge position to return to the storage position after the rubber mass has been discharged, and moves within the plane from the intervening position toward the standby position after the mixing tank has rotated from the discharge position to return to the storage position; an air cylinder having a cylindrical housing and a rod whose tip is fixed to the plate-like member and can be freely inserted and removed from the housing, the air cylinder moving the plate-like member between the standby position and the interposition position by inserting and removing the rod; When the rod is extended from the housing to a maximum extent, the plate-like member reaches the interposed position, a first sensor that detects when the rod is fully extended from the housing portion; The mixing tank rotates from the accommodation position to the discharge position when the first sensor detects that the rod has been extended to the maximum extent from the housing portion.

2. A kneader for kneading a rubber composition to form a rubber dough, comprising: a mixing tank having an opening, the opening direction of which can be switched between a predetermined upward direction and a predetermined downward direction by rotating, the mixing tank storing a rubber composition in a storing position in which the opening is open in the predetermined upward direction, and discharging a rubber material obtained by kneading the rubber composition in a discharging position in which the opening is open in the predetermined downward direction; a pressurizing lid which enters the mixing tank in the accommodation position through the opening from a direction opposite to the predetermined upward direction to pressurize the rubber composition accommodated in the mixing tank, and which exits the mixing tank through the opening in the predetermined upward direction after kneading the rubber composition; a shaft member that is provided within the mixing tank and has a blade on its circumferential surface that protrudes in a direction away from a central axis and rotates around the central axis, the shaft member kneading the rubber composition by stirring the rubber composition contained in the mixing tank and pressed by the pressure lid with the rotating blade to form the rubber mass; a plate-like member extending within a plane intersecting the predetermined upward direction, which waits at a predetermined standby position away from the pressurizing lid and the mixing tank while the pressurizing lid is in the mixing tank, moves from the standby position within the plane toward an intervening position between the mixing tank and the pressurizing lid after the pressurizing lid has left the mixing tank and before the mixing tank rotates from the storage position to the discharge position, and is intervening between the mixing tank and the pressurizing lid at the intervening position until the mixing tank rotates from the storage position to the discharge position to discharge the rubber mass and rotates from the discharge position to return to the storage position after the rubber mass has been discharged, and moves within the plane from the intervening position toward the standby position after the mixing tank has rotated from the discharge position to return to the storage position; an air cylinder having a cylindrical housing and a rod whose tip is fixed to the plate-like member and can be freely inserted and removed from the housing, the air cylinder moving the plate-like member between the standby position and the interposition position by inserting and removing the rod; When the rod is inserted into the housing to a maximum extent, the plate-like member reaches the standby position, a second sensor for detecting when the rod is fully inserted into the housing portion; A kneader in which the pressurizing lid begins to move toward the mixing tank to re-enter the mixing tank when the second sensor detects that the rod has been inserted to its maximum extent into the housing portion.

3. A kneading machine as described in claim 1 or 2, comprising a stand that supports the plate-shaped member at the waiting position.

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