Method and apparatus for manufacturing a rubber member

Abstract

To provide a rubber member manufacturing method and apparatus capable of manufacturing a rubber member having a desired cross-sectional shape with high productivity by molding an extruded unvulcanized rubber.SOLUTION: There is provided a rubber member manufacturing method in which: when a rubber member S that is molded by extruding an unvulcanized rubber R from a die 3 provided at a front end of an extruder 2 is placed on a rotary drive roller 5a installed in front of the die 3 and pulled forward, a separation distance L between the die 3 and the rotary drive roller 5a on which the rubber member S is placed is changed, by using a separation distance variable mechanism 6, according to an extrusion speed V of the unvulcanized rubber R, so that a time for relaxing a residual stress of the rubber member S between the die 3 and the rotary drive roller 5a is adjusted; and even if the extrusion speed V changes, the rubber member S having a desired cross-sectional shape can be obtained by correcting variation in a magnitude of the residual stress.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for manufacturing a rubber member, and more particularly, to a method and an apparatus for manufacturing a rubber member that can produce a rubber member formed by extruding unvulcanized rubber into a desired cross-sectional shape with high productivity.

Background Art

[0002] In the manufacturing process of rubber products such as tires, rubber members manufactured by extruding unvulcanized rubber by an extruder are used. When passing through the extrusion flow path at the front end of the extruder, the unvulcanized rubber is shaped into a predetermined shape and extruded (see, for example, Patent Document 1).

[0003] When the unvulcanized rubber is released from the restraint of the die, it has the property of expanding in the width direction and the thickness direction and contracting in the longitudinal direction (hereinafter referred to as swell). This swell occurs because the strain energy (residual stress) remaining in the shaped unvulcanized rubber tries to return the unvulcanized rubber to the state before being shaped. Due to this swell, the cross-sectional shape of the extruded rubber member changes over time, which becomes an obstacle to ensuring a desired cross-sectional shape.

[0004] Therefore, in order to reduce the residual stress, there is a drawback that if the extrusion speed of the unvulcanized rubber is made slower, the productivity of the rubber member decreases. Alternatively, if measures such as making the die extrusion flow path longer are taken to increase the time for stress relaxation and reduce the residual stress, there is a drawback that the load on the extrusion equipment becomes excessive. Furthermore, when the extrusion speed is different, the time for stress relaxation in the die changes, and accordingly, the magnitude of the residual stress also changes, resulting in variations in the cross-sectional shape of the rubber member. Therefore, there is room for improvement in producing a rubber member formed by extruding unvulcanized rubber into a desired cross-sectional shape with high productivity.

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 method and an apparatus for manufacturing a rubber member that can produce a rubber member obtained by extruding and molding an unvulcanized rubber into a desired cross-sectional shape with high productivity.

Means for Solving the Problems

[0007] In order to achieve the above object, a method for manufacturing a rubber member according to the present invention is a method for manufacturing a rubber member in which an unvulcanized rubber is extruded from a die attached to the front end of an extruder, and the rubber member molded by the die is pulled forward while being placed on a pulling means disposed in front of the die, characterized in that a separation distance between the die and the pulling means on which the rubber member is placed is changed according to an extrusion speed of the unvulcanized rubber.

[0008] A manufacturing apparatus for a rubber member according to the present invention includes an extruder that extrudes an unvulcanized rubber, and a pulling means disposed in front of a die attached to the front end of the extruder, and in the manufacturing apparatus for a rubber member in which the rubber member molded by the die from the unvulcanized rubber is pulled forward while being placed on the pulling means, it is characterized by having a separation distance variable mechanism that changes a separation distance between the die and the pulling means on which the rubber member is placed according to an extrusion speed of the unvulcanized rubber.

Effects of the Invention

[0009] According to the present invention, by changing the separation distance according to the extrusion speed of the unvulcanized rubber, it is possible to adjust the time for relaxing the residual stress on the rubber member molded and extruded by the drawing means. As a result, even if the extrusion speed changes, the variation in the magnitude of the residual stress can be corrected, which is advantageous for obtaining a rubber member with a desired cross-sectional shape. In addition, since it is not necessary to forcibly slow down the extrusion speed to ensure a rubber member with a desired cross-sectional shape, it is advantageous for producing the rubber member with high productivity.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the method and apparatus for manufacturing a rubber member of the present invention will be described based on the embodiments shown in the drawings.

[0012] The embodiment of the manufacturing apparatus 1 of the rubber member illustrated in FIGS. 1 to 2 manufactures an unvulcanized rubber R by extrusion to produce a strip-shaped rubber member S having a desired cross-sectional shape. The cross-sectional shape of the rubber member S is not particularly limited, and a desired shape such as a circular shape, an elliptical shape, a triangular shape, a square shape, or other polygonal shapes is adopted. The width dimension (diameter dimension) of the rubber member S is, for example, about 5 mm to 30 mm.

[0013] This manufacturing apparatus 1 includes an extruder 2 that extrudes the unvulcanized rubber R, a drawing means 5 disposed in front of the extruder 2, and a separation distance variable mechanism 6. In this embodiment, it further has a support roller 7, a conveying conveyor 8, and a drum body 9 disposed in front of the drawing means 5. The support roller 7, the conveying conveyor 8, and the drum body 9 are arbitrarily installed as required on the manufacturing line of the rubber member S. The left-right direction of the drawing is the front-rear direction in the manufacturing apparatus 1, and the left side and the right side of the drawing are the front and the rear in the manufacturing apparatus 1, respectively.

[0014] The extruder 2 includes a cylindrical cylinder 2a, a screw 2b disposed inside the cylinder 2a, and a head 2c installed at the front end of the cylinder 2a. A die 3 is detachably attached to the front end of the head 2c. An extrusion flow path 4 communicating in the front-rear direction is formed in the die 3. The extrusion flow path 4 communicates with the inside of the cylinder 2a. Note that various known specifications of the extruder 2 can be used, for example, a specification in which a gear pump is provided in the head 2c may be used.

[0015] The unvulcanized rubber R charged into the inside of the cylinder 2a is sent forward inside the cylinder 2a by the screw 2b rotationally driven by a drive motor while its viscosity is lowered (plasticized). By passing through the extrusion flow path 4, this unvulcanized rubber R is shaped and extruded as the rubber member S from the outlet of the extrusion flow path 4 that opens on the front end surface of the die 3. The outline of the cross-sectional shape of the rubber member S is determined by the cross-sectional shape of the extrusion flow path 4. Since the die 3 is detachably attached to the head 2c, a die 3 having an extrusion flow path 4 with a corresponding cross-sectional shape is attached to the head 2c according to the cross-sectional shape of the rubber member S to be manufactured.

[0016] The drawing-out means 5 is disposed in front of the die 3, and the rubber member S shaped by the die 3 is placed thereon. The drawing-out means 5 draws the rubber member S forward while placing it. In this embodiment, a rotation drive roller 5a is adopted as the drawing-out means 5. This rotation drive roller 5a extends in a direction crossing the placed rubber member S. That is, the extending direction of the axis of the rotation drive roller 5a and the extending direction of the rubber member S are orthogonal. The drawing-out speed of the rubber member S by the rotation drive roller 5a (drawing-out means 5) is controlled by a control unit 6c described later.

[0017] The separation distance variable mechanism 6 changes the separation distance L between the die 3 and the rotation drive roller 5a on which the rubber member S is placed according to the extrusion speed V of the unvulcanized rubber R by the extruder 2. The separation distance L, in detail, is the front-rear direction separation distance between the front end face of the die 3 and the axis of the rotation drive roller 5a.

[0018] In this embodiment, the separation distance variable mechanism 6 has a variable drive unit 6a that moves the rotation drive roller 5a in the front-rear direction, a guide unit 6b, and a control unit 6c. As the variable drive unit 6a, various fluid cylinders, rods that move back and forth with a servo motor, etc. can be used. The guide unit 6b guides the rotation drive roller 5a that moves back and forth in the front-rear direction so as not to deviate.

[0019] The control unit 6c controls the movement of the variable drive unit 6a. A computer is used as the control unit 6c. Data of the extrusion speed V is input to the control unit 6c. This extrusion speed V is directly or indirectly detected as the flow rate of the unvulcanized rubber R passing through the head 3 and the die 4. For example, if it is an extruder 2 equipped with a head pressure, the rotation speed of the screw 2b, or a gear pump, data of the rotation speed of the gear pump, etc. can be used to grasp it. The control unit 6c controls the movement of the variable drive unit 6a based on the data of the extrusion speed V to make the separation distance L the target value. In this embodiment, the drawing-out speed of the rotation drive roller 5a (drawing-out means 5) is also controlled by the control unit 6c, but the drawing-out speed can also be controlled by another control unit.

[0020] A rubber member S is placed on the support roller 7, and the rubber member S hangs down by its own weight between the support roller 7 and the rotation drive roller 5a. This hanging part of the rubber member S becomes the excess length (the festoon part) in the manufacturing line of the rubber member S.

[0021] The rubber member S is placed on the conveying conveyor 8, and the placed rubber member S is conveyed forward. The conveying conveyor 8 can adopt various known types, such as a type equipped with a conveyor belt made of rubber or resin.

[0022] The rubber member S is wound around the outer peripheral surface of the drum body 9 formed in a cylindrical shape using a pressure roller or the like. The rubber member S may be wound around the outer peripheral surface of another member already wound around the outer peripheral surface of the drum body 9. Therefore, the rubber member S is wound around the outer peripheral surface of the drum body 9 directly or indirectly. The drum body 9 is not limited to a so-called forming drum, and may be a rigid core having an outer peripheral surface with the same shape as the inner peripheral surface of the completed tire.

[0023] A slide mechanism 9a is connected to the drum body 9. In this embodiment, an actuator such as a hydraulic cylinder is used as the slide mechanism 9a. By the advance and retreat of the cylinder rod of the slide mechanism 9a, the drum body 9 slides in the drum width direction. The slide mechanism 9a slides the rotating drum body 9. In this drum body 9, the rubber member S is formed into an annular rubber member Sc. This annular rubber member Sc is a concept including a cylindrical rubber member.

[0024] Even if the conveying conveyor 8 is slid without sliding the drum body 9 in the drum width direction, or both the drum body 9 and the conveying conveyor 8 are slid. Incidentally, when sliding the conveying conveyor 8, for example, the support roller 7, the rotation drive roller 5a, and the extruder 2 are slid in synchronization with the conveying conveyor 8.

[0025] Next, an example of the procedure of the manufacturing method of the rubber member according to the present invention will be described.

[0026] As illustrated in FIGS. 1 and 2, the unvulcanized rubber R is extruded from the die 3 attached to the front end of the extruder 2 to form the rubber member S. This rubber member S is placed on the rotation drive roller 5a and is substantially stretched without slack between the die 3 and the rotation drive roller 5a. In this state, the rubber member S is pulled forward by the rotation drive roller 5a and is placed on the conveyor 8 via the support roller 7.

[0027] The pulling speed of the rubber member S by the rotation drive roller 5a is set to at least a level where the rubber member S does not slack and within a range where the rubber member S does not break. For example, when the extrusion speed is defined as the speed at which the cross-sectional area of the rubber member S on the rotation drive roller 5a is equal to the cross-sectional area defined by the die 3, the allowable range of the pulling speed is about 60% to 200% of this extrusion speed. Incidentally, even if the pulling speed is slower than this extrusion speed (even about 60% of the extrusion speed), the cross-sectional area of the rubber member S may become larger than the cross-sectional area defined by the die 3 due to swell, so it may be in a non-slack state. Next, the rubber member S is conveyed to the drum body 9 by the conveyor 8.

[0028] The drum body 9 rotates and is slid in the drum width direction by the slide mechanism 9a. The rubber member S conveyed by the conveyor 8 is pressed toward the outer peripheral surface of the drum body 9 by a crimping roller or the like and is disposed on the outer peripheral surface of the drum body 9. Thereby, the rubber member S is spirally wound around the drum body 9 while shifting the drum width direction position with respect to the drum body 9. The conveying speed of the rubber member S by the conveyor 8 and the circumferential speed of the outer peripheral surface of the drum body 9 are controlled to be substantially the same speed without causing a large difference basically.

[0029] The rubber members S wound adjacent to each other in the drum width direction are joined together by their own adhesiveness. The drum body 9 not only slides in one direction in the drum width direction but may also slide back and forth in the drum width direction as necessary, and the rubber member S may be wound. When the rubber member S is cut to the required length and wound, a cylindrical rubber member Sc is produced on the outer peripheral surface of the drum body 9. Such a cylindrical rubber member Sc becomes a member forming, for example, a tire tread portion.

[0030] The rubber member S is shaped by the die 3, but a time-dependent shape change occurs due to swelling immediately after being released from the restraint of the die 3. If the extruded rubber member S is not subject to any restraint, the swelling effect is maximum immediately after being extruded from the die 3, so it expands more in the width and thickness directions and contracts more in the longitudinal direction. Then, as time passes after being extruded from the die 3, the influence of swelling decreases, and the degree of the time-dependent shape change of the rubber member S becomes smaller.

[0031] Here, the rubber member S is placed on and adheres to the rotation drive roller 5a, and thus is temporarily restrained by the rotation drive roller 5a. Therefore, between the die 3 and the rotation drive roller 5a (within the separation distance L), the freely deformable shape of the rubber member S due to swelling is suppressed, and the residual stress is relaxed. A difference occurs in the subsequent shape (cross-sectional shape) of the rubber member S due to the difference in the length of time for which this residual stress is relaxed.

[0032] The faster the extrusion speed V, the shorter the time for the rubber member S to pass between the die 3 and the rotation drive roller 5a (within the separation distance L), so the time for the residual stress to be relaxed becomes shorter. Therefore, if the separation distance L remains unchanged even when the extrusion speed V changes, the subsequent shape (cross-sectional shape) of the rubber member S will be different due to swelling.

[0033] In order to obtain a rubber member S with a constant quality, the extruder 2 basically continues to extrude the unvulcanized rubber R at an extrusion speed V within a certain allowable range, but the extrusion speed V may also be changed midway. Further, since the appropriate extrusion speed V differs depending on the specifications (rubber type) of the unvulcanized rubber R, it is set to different extrusion speeds V according to the specifications of the unvulcanized rubber R.

[0034] Therefore, in the present invention, the separation distance displacement mechanism 6 is used to change the separation distance L according to the extrusion speed V as illustrated in FIG. 3. In FIG. 3, the rotary drive roller 5a and the rubber member S before changing the separation distance L are shown by thin dashed lines. Basically, control is performed such that the separation distance L is increased as the extrusion speed V is higher, and the separation distance L is decreased as the extrusion speed V is lower.

[0035] In the present invention, by changing the separation distance L, even when the extrusion speed V changes, the time for relaxing the residual stress of the rubber member S between the die 3 and the rotary drive roller 5a can be made uniform. Along with this, variations in the magnitude of the residual stress can be corrected, so variations in the shape (cross-sectional shape) of the rubber member S due to swell are suppressed, and it becomes easier to ensure the desired cross-sectional shape. In this embodiment, since the separation distance L can be adjusted steplessly, the magnitude of the residual stress can be further corrected with less variation.

[0036] Further, in order to ensure a rubber member S with a desired cross-sectional shape, it is not necessary to forcibly slow down the extrusion speed V to suppress the influence of swell. Therefore, it is advantageous for productively manufacturing the rubber member S.

[0037] By using the rubber member S having a desired cross-sectional shape with suppressed variations in this way, it is advantageous for forming an annular (cylindrical) rubber member Sc manufactured by spirally winding the rubber member S into a desired shape with higher accuracy. As a result, it contributes to improving the uniformity of a tire manufactured using this rubber member Sc.

[0038] In the production line of this rubber member S, the excess length of the rubber member S is absorbed between the rotation drive roller 5a and the support roller 7. Therefore, even when temporarily stopping the rotation of the drum body 9 to remove the produced rubber member Sc from the drum body 9 or during an interval such as replacing the drum body 9, the extruder 2 can continue to extrude the rubber member S as it is.

[0039] The degree of shape change of the rubber member S due to swell is maximum immediately after extrusion and decreases as time passes. Therefore, suppressing the free deformation of the rubber member S due to swell in a region as close as possible to the front end face of the die 3 is increasingly advantageous for reducing the variation in the cross-sectional shape of the rubber member S and ensuring a rubber member S having a desired cross-sectional shape. Therefore, the rotation drive roller 5a is arranged in a region as close as possible to the front end face of the die 3, and the separation distance L is preferably, for example, within 50 cm, and more preferably within 20 cm.

[0040] The degree of swell varies depending on the specifications of the unvulcanized rubber R. Therefore, for each specification of the unvulcanized rubber R, it is advisable to grasp in advance the appropriate range of the separation distance L that changes according to the extrusion speed V as prior data and store it in the control unit 6c. When manufacturing the rubber member S, by inputting specific data for specifying the specifications of the unvulcanized rubber R into the control unit 6c, the control unit 6c changes the separation distance L to an appropriate range according to the extrusion speed V based on this specific data and the previously grasped prior data. Thereby, even when manufacturing the rubber member S using unvulcanized rubbers R of various specifications, the separation distance L can be more reliably controlled within an appropriate range.

[0041] As illustrated in FIG. 4, a belt conveyor 5b can also be used as the drawing means 5. This embodiment is different only in that the drawing means 5 is different from the previous embodiment, and the other configurations are substantially the same. This belt conveyor 5b is also controlled to change the separation distance L according to the extrusion speed V, like the rotation drive roller 5a in the previous embodiment. When using the belt conveyor 5b, the contact area with the rubber member S becomes larger than that of the rotation drive roller 5a, so the rubber member S can be restrained more stably.

[0042] In the embodiment of the manufacturing apparatus 1 illustrated in FIGS. 5 and 6, the drawing means 5 has a plurality of rotationally driven rollers 5a arranged in a vertical row. This embodiment is different only in the drawing means 5 from the embodiment described above, and the other configurations are substantially the same. Each rotationally driven roller 5a is disposed at a height position of a placement level on which the rubber member S is placed. Each rotationally driven roller 5a is vertically movable by a variable drive unit 6a such as a fluid cylinder. In this embodiment, the distance L is formed between the rotationally driven roller 5a on which the rubber member S is placed and is disposed closest to the die 3 and the die 3.

[0043] In this embodiment, according to the extrusion speed V, the distance L is changed by moving at least one rotationally driven roller 5a downward from the placement level by the variable drive unit 6a. As illustrated in FIG. 7, when the rotationally driven roller 5a disposed closest to the die 3 is moved downward from the placement level, the rotationally driven roller 5a adjacent to this rotationally driven roller 5a will have the rubber member S placed thereon and be disposed closest to the die 3, so that the distance L becomes larger. By moving the rotationally driven roller 5a disposed closest to the die 3 and the rotationally driven roller 5a adjacent thereto (i.e., the two rotationally driven rollers 5a disposed on the die 3 side) downward from the placement level, the distance L becomes even larger. When reducing the distance L, an operation opposite to that for increasing the distance L may be performed.

[0044] In this embodiment, the distance L does not change continuously, but changes to a plurality of types preset based on the arrangement of each rotationally driven roller 5a arranged in a vertical row. The number of rotationally driven rollers 5a arranged in a vertical row is appropriately determined, but is, for example, about 2 to 5.

[0045] The drum body 9 is not limited to a simple cylindrical shape. The outer peripheral surface of the drum body 9 illustrated in FIGS. 8 and 9 has the same profile as the inner peripheral surface of the completed tire. As the drum body 9 having such a shape, the rigid core described above can be exemplified.

[0046] In this drum body 9, for example, a rubber member S is spirally wound around both end portions in the width direction of the outer peripheral surface of the rotating drum body 9 to produce an annular rubber member Sc. The rubber member S may be directly wound around the outer peripheral surface of the drum body 9, or may be wound around the outer peripheral surface of another member (inner liner and carcass layer) already wound around the outer peripheral surface of the drum body 9. The rubber member S is wound in a spiral shape along the outer peripheral surface of the drum body 9. In this embodiment, the produced annular rubber member Sc becomes a member forming the tire side portion. It is also possible to produce a cylindrical rubber member Sc by spirally winding the rubber member S around the central portion in the width direction of the rotating drum body 9.

[0047] In addition, the configurations described in each of the above-described embodiments can be applied to other embodiments within the possible range.

Explanation of Reference Numerals

[0048] 1 Manufacturing apparatus for rubber member 2 Extruder 2a Cylinder 2b Screw 2c Head 3 Die 4 Extrusion channel 5 Drawing means 5a Rotation drive roller 5b Belt conveyor 6 Spacing variable mechanism 6a Variable drive unit 6b Guide portion 6c Control portion 7 Support roller 8 Conveyor 9 Drum body 9a Slide mechanism S Rubber member Sc Annular (cylindrical) rubber member R Unvulcanized rubber

Claims

1. In a method for manufacturing a rubber member, unvulcanized rubber is extruded from a die attached to the front end of an extruder, and the rubber member shaped by the die is drawn forward while being placed on drawing means arranged in front of the die, a method for manufacturing a rubber member, characterized in that a separation distance between the die and the drawing means on which the rubber member is placed is changed according to an extrusion speed of the unvulcanized rubber.

2. The method for manufacturing a rubber member according to claim 1, wherein a rotationally driven roller extending in a direction crossing the rubber member is used as the drawing means.

3. The method for manufacturing a rubber member according to claim 1, wherein a belt conveyor is used as the drawing means.

4. The method for manufacturing a rubber member according to any one of claims 1 to 3, wherein a plurality of the drawing means are arranged in a vertical row, each of the drawing means is arranged at a height position of a placement level on which the rubber member is placed, and at least one of the drawing means is moved downward from the placement level to change the separation distance.

5. The method for manufacturing a rubber member according to any one of claims 1 to 4, wherein the rubber member is spirally wound around an outer peripheral surface of a drum body arranged in front of the drawing means to be formed into an annular shape.

6. For each specification of the unvulcanized rubber, an appropriate range of the separation distance that is changed according to the extrusion speed is grasped in advance as pre-data and stored in a control unit, and specific data for specifying the specification of the unvulcanized rubber is input to the control unit, so that the control unit changes the separation distance to the appropriate range according to the extrusion speed based on the specific data and the pre-data. The method for manufacturing a rubber member according to any one of claims 1 to 5.

7. A manufacturing apparatus for a rubber member, comprising an extruder for extruding unvulcanized rubber and drawing means arranged in front of a die attached to the front end of the extruder, wherein the rubber member shaped by the die with the unvulcanized rubber is drawn forward while being placed on the drawing means, a manufacturing apparatus for a rubber member, characterized by having a separation distance variable mechanism that changes a separation distance between the die and the drawing means on which the rubber member is placed according to an extrusion speed of the unvulcanized rubber.

Images