JP7709031B2 - Manufacturing method and device for rubber member - Google Patents

Description

The present invention relates to a method and apparatus for manufacturing rubber members, and more specifically, to a method and apparatus for manufacturing rubber members that can be produced with high productivity while forming rubber members into the desired cross-sectional shape by extruding unvulcanized rubber and molding it.

In the manufacturing process of rubber products such as tires, rubber components are used that are manufactured by extruding unvulcanized rubber with an extruder. When the unvulcanized rubber passes through the extrusion flow path at the front end of the extruder, it is molded into a predetermined shape and extruded (see, for example, Patent Document 1).

When unvulcanized rubber is released from the constraints of the die, it has the property of expanding in the width and thickness directions and shrinking in the length direction (hereafter referred to as swell). This swell occurs when the strain energy (residual stress) remaining in the molded unvulcanized rubber tries to return the unvulcanized rubber to the state it was in before it was molded. This swell causes the cross-sectional shape of the extruded rubber to change over time, which is an obstacle to ensuring the desired cross-sectional shape.

Therefore, if the extrusion speed of the unvulcanized rubber is slowed down in order to reduce the residual stress, there is a disadvantage that the productivity of the rubber part decreases. Alternatively, if the time for the stress to relax is increased by measures such as making it longer than the extrusion flow path of the die, thereby reducing the residual stress, there is a disadvantage that the load on the extrusion equipment becomes excessive. Furthermore, if the extrusion speed differs, the time for the stress to relax in the die changes, and therefore the magnitude of the residual stress also changes, causing variation in the cross-sectional shape of the rubber part. Therefore, there is room for improvement in manufacturing rubber parts that have been extruded and shaped from unvulcanized rubber with the desired cross-sectional shape while being produced with good productivity.

JP 2009-143165 A

The object of the present invention is to provide a method and apparatus for producing rubber members that can be produced with high productivity while forming rubber members of the desired cross-sectional shape by extruding unvulcanized rubber and molding them.

To achieve the above object, the method for manufacturing a rubber member of the present invention is characterized in that, in the 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 placed on a drawing means arranged in front of the die and drawn forward, the distance between the die and the drawing means on which the rubber member is placed is changed according to the extrusion speed of the unvulcanized rubber.

The rubber member manufacturing device of the present invention is equipped with an extruder that extrudes unvulcanized rubber and a drawing means arranged in front of a die attached to the front end of the extruder, and the rubber member formed by shaping the unvulcanized rubber with the die is placed on the drawing means and drawn forward, and is characterized in that it has a distance varying mechanism that changes the distance between the die and the drawing means on which the rubber member is placed in accordance with the extrusion speed of the unvulcanized rubber.

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 the drawing means to relax the residual stress in the shaped and extruded rubber member. 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 there is no need to forcibly slow down the extrusion speed to ensure a rubber member with a desired cross-sectional shape, this is advantageous for manufacturing rubber members with good productivity.

FIG. 2 is an explanatory diagram illustrating an embodiment of a rubber member manufacturing apparatus of the present invention as seen from the side; FIG. 2 is an explanatory diagram illustrating the manufacturing apparatus of FIG. 1 in a plan view. 2 is an explanatory diagram illustrating a state in which the rotation drive roller in FIG. 1 has been moved; FIG. 1. FIG. 4 is an explanatory diagram showing a modified example of the drawing means of FIG. FIG. 4 is an explanatory diagram illustrating a side view of another embodiment of the rubber member manufacturing apparatus. 6 is an explanatory diagram illustrating an enlarged example of the periphery of the drawer means in FIG. 5 . FIG. 6 is an explanatory diagram illustrating a state in which one of the rotation drive rollers in FIG. 5 is moved downward; FIG. 1. FIG. 4 is an explanatory diagram illustrating a modification of the drum body of FIG. 1 in a left half cross-sectional view. FIG. 9 is an explanatory diagram showing the drum body of FIG. 8 as seen from the side.

The method and device for manufacturing rubber members of the present invention will be described below based on the embodiment shown in the figures.

The embodiment of the rubber member manufacturing device 1 illustrated in Figures 1 and 2 extrudes unvulcanized rubber R to manufacture 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 any desired shape may be used, such as a circle, an ellipse, a triangle, a rectangle, or any other polygonal shape. The width dimension (diameter dimension) of the rubber member S is, for example, about 5 mm to 30 mm.

This manufacturing apparatus 1 is equipped with an extruder 2 that extrudes unvulcanized rubber R, a drawing means 5 arranged in front of the extruder 2, and a distance variable mechanism 6. This embodiment further includes a support roller 7, a transport conveyor 8, and a drum body 9 arranged in front of the drawing means 5. The support roller 7, the transport conveyor 8, and the drum body 9 are installed as required for the manufacturing line of the rubber member S. The left-right direction of the drawing is the front-rear direction of the manufacturing apparatus 1, and the left and right sides of the drawing are the front and rear of the manufacturing apparatus 1, respectively.

The extruder 2 comprises 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. The die 3 is formed with an extrusion flow path 4 that communicates in the front-rear direction. The extrusion flow path 4 communicates with the inside of the cylinder 2a. Note that various known specifications can be used as the extruder 2, and for example, the head 2c may be equipped with a gear pump.

Unvulcanized rubber R fed into the cylinder 2a is sent forward inside the cylinder 2a by the screw 2b, which is driven to rotate by the drive motor, while its viscosity is reduced (plasticized). This unvulcanized rubber R is shaped as it passes through the extrusion flow path 4, and is extruded as rubber material S from the outlet of the extrusion flow path 4, which opens on the front end face of the die 3. The cross-sectional shape of the rubber material S is determined by the cross-sectional shape of the extrusion flow path 4. The die 3 is detachable from the head 2c, so that the die 3, in which the extrusion flow path 4 with a cross-sectional shape corresponding to the cross-sectional shape of the rubber material S to be manufactured, is attached to the head 2c.

The drawing means 5 is disposed in front of the die 3, and the rubber member S shaped by the die 3 is placed on it. The drawing means 5 draws the rubber member S forward while placing it on it. In this embodiment, a rotation drive roller 5a is used as the drawing means 5. This rotation drive roller 5a extends in a direction that crosses the placed rubber member S. In other words, the extension direction of the axis of the rotation drive roller 5a and the extension direction of the rubber member S are perpendicular to each other. The drawing speed of the rubber member S by the rotation drive roller 5a (drawing means 5) is controlled by the control unit 6c, which will be described later.

The variable distance mechanism 6 changes the distance L between the die 3 and the rotary drive roller 5a on which the rubber material S is placed, depending on the extrusion speed V of the unvulcanized rubber R by the extruder 2. More specifically, the distance L is the distance in the front-to-rear direction between the front end face of the die 3 and the axis of the rotary drive roller 5a.

In this embodiment, the variable separation distance mechanism 6 has a variable drive unit 6a that moves the rotary drive roller 5a in the forward and backward directions, a guide unit 6b, and a control unit 6c. The variable drive unit 6a can be a variety of fluid cylinders or a rod that moves forward and backward using a servo motor. The guide unit 6b guides the rotary drive roller 5a in the forward and backward directions so that it does not deviate from the original position.

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

The rubber member S is placed on the support roller 7, and the rubber member S hangs down due to 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 (festoon portion) on the manufacturing line for the rubber member S.

The rubber material S is placed on the transport conveyor 8, and the placed rubber material S is transported forward. The transport conveyor 8 can be of various known types, such as a type equipped with a rubber or resin conveyor belt.

The rubber material S is wound around the outer circumferential surface of the drum body 9, which is formed into a cylindrical shape, using a pressure roller or the like. The rubber material S may also be wound around the outer circumferential surface of another material that is already wound around the outer circumferential surface of the drum body 9. Therefore, the rubber material S is wound directly or indirectly around the outer circumferential surface of the drum body 9. The drum body 9 is not limited to a so-called molding drum, and may also be a rigid core whose outer circumferential surface has the same shape as the inner circumferential surface of the finished tire.

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. The cylinder rod of the slide mechanism 9a moves back and forth, causing the drum body 9 to slide in the drum width direction. The slide mechanism 9a slides the drum body 9 while it is rotating. In this drum body 9, the rubber member S is molded into annular rubber member Sc. This annular rubber member Sc is a concept that also includes cylindrical rubber members.

The conveyor 8 may be slid without sliding the drum body 9 in the drum width direction, or both the drum body 9 and the conveyor 8 may be slid. When the conveyor 8 is slid, for example, the support roller 7, the rotation drive roller 5a, and the extruder 2 are slid in synchronization with the conveyor 8.

Next, an example of the procedure for manufacturing a rubber member according to the present invention will be described.

As shown in Figures 1 and 2, unvulcanized rubber R is extruded from a die 3 attached to the front end of an extruder 2 to form a rubber member S. This rubber member S is placed on a rotary drive roller 5a and is stretched between the die 3 and the rotary drive roller 5a with virtually no slack. In this state, the rubber member S is pulled forward by the rotary drive roller 5a and placed on the transport conveyor 8 via a support roller 7.

The pulling speed of the rubber member S by the rotary drive roller 5a is set to a range at which the rubber member S does not loosen and at which the rubber member S does not break. For example, if the extrusion speed is defined as the speed at which the cross-sectional area of the rubber member S on the rotary drive roller 5a becomes 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. Note that 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, and the rubber member S may not become loose. Next, the rubber member S is transported to the drum body 9 by the transport conveyor 8.

While rotating, the drum body 9 is slid in the drum width direction by the slide mechanism 9a. The rubber material S transported by the transport conveyor 8 is pressed toward the outer peripheral surface of the drum body 9 by a pressure roller or the like and placed on the outer peripheral surface of the drum body 9. This causes the rubber material S to be wound in a spiral shape while shifting its position in the drum width direction relative to the drum body 9. The transport speed of the rubber material S by the transport conveyor 8 and the circumferential speed of the outer peripheral surface of the drum body 9 are basically controlled to be substantially the same speed without causing a large difference.

The rubber members S that are wrapped next to each other in the drum width direction are bonded together by their own adhesiveness. The drum body 9 does not only slide in one direction in the drum width direction, but also slides back and forth in the drum width direction as necessary to wrap the rubber members S. When the rubber members S are cut to the required length and wrapped around the drum body 9, a cylindrical rubber member Sc is produced on the outer circumferential surface of the drum body 9. Such a cylindrical rubber member Sc becomes, for example, a member that forms the tire tread portion.

The rubber material S is shaped by the die 3, but immediately after it is released from the constraints of the die 3, a change in shape occurs over time due to swell. If the extruded rubber material S is not constrained in any way, the effect of swell is greatest immediately after it is 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 it is extruded from the die 3, the effect of swell decreases, and the degree of change in shape of the rubber material S over time becomes smaller.

Here, the rubber member S is placed on and adheres to the rotation drive roller 5a, and is temporarily restrained by the rotation drive roller 5a. Therefore, between the die 3 and the rotation drive roller 5a (separation distance L), the rubber member S in a tensioned state is suppressed from freely deforming due to swell, and residual stress is relaxed. Differences in the length of time it takes for this residual stress to be relaxed result in differences in the subsequent shape (cross-sectional shape) of the rubber member S.

The faster the extrusion speed V, the shorter the time it takes for the rubber member S to pass between the die 3 and the rotary drive roller 5a (across the separation distance L), and therefore the shorter the time it takes for the residual stress to relax. Therefore, if the separation distance L remains constant even when the extrusion speed V changes, the subsequent shape (cross-sectional shape) of the rubber member S will differ due to swell.

To obtain a rubber part S of consistent quality, the extruder 2 continues to extrude the unvulcanized rubber R at an extrusion speed V that is basically within a certain allowable range, but the extrusion speed V may be changed midway. Also, since the appropriate extrusion speed V differs depending on the specifications (rubber type) of the unvulcanized rubber R, a different extrusion speed V is set according to the specifications of the unvulcanized rubber R.

In the present invention, therefore, a separation distance change 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 rotation drive roller 5a and the rubber member S before the separation distance L is changed are indicated by thin dashed lines. Basically, the separation distance L is controlled so that the faster the extrusion speed V is, the larger the separation distance L is, and the slower the extrusion speed V is, the smaller the separation distance L is.

In the present invention, by changing the separation distance L, the time it takes for the residual stress in the rubber member S to relax between the die 3 and the rotation drive roller 5a can be made uniform, even if the extrusion speed V changes. As a result, the variation in the magnitude of the residual stress can be corrected, so the variation in the shape (cross-sectional shape) of the rubber member S caused by swell is suppressed, making it easier to ensure the desired cross-sectional shape. In this embodiment, the separation distance L can be adjusted continuously, so the variation in the magnitude of the residual stress can be further reduced and corrected.

In addition, in order to ensure that the rubber member S has the desired cross-sectional shape, it is not necessary to suppress the effects of swell by forcibly slowing down the extrusion speed V. This is advantageous for manufacturing the rubber member S with good productivity.

By using a rubber member S having a desired cross-sectional shape with reduced variation in this way, it is advantageous to form the annular (cylindrical) rubber member Sc, which is manufactured by winding the rubber member S in a spiral shape, into the desired shape with greater precision. As a result, this contributes to improving the uniformity of tires manufactured using this rubber member Sc.

In this manufacturing line for rubber member S, the excess length of rubber member S is absorbed between the rotation drive roller 5a and the support roller 7. Therefore, even when the rotation of the drum body 9 is temporarily stopped to remove the manufactured rubber member Sc from the drum body 9 or during intervals such as when replacing the drum body 9, the extruder 2 can continue to extrude the rubber member S.

The degree of change in shape of the rubber member S due to swell is greatest immediately after extrusion and decreases as time passes. Therefore, if free deformation of the rubber member S due to swell is suppressed in an area as close as possible to the front end face of the die 3, it is more advantageous to reduce the variation in the cross-sectional shape of the rubber member S and ensure that the rubber member S has the desired cross-sectional shape. Therefore, the rotation drive roller 5a is preferably placed in an area as close as possible to the front end face of the die 3, and the separation distance L is, for example, within 50 cm, and more preferably within 20 cm.

The degree of swell varies depending on the specifications of the unvulcanized rubber R. Therefore, it is advisable to determine in advance as advance data the appropriate range of the separation distance L, which is changed according to the extrusion speed V, for each specification of the unvulcanized rubber R and store it in the control unit 6c. When manufacturing the rubber member S, specific data specifying the specifications of the unvulcanized rubber R is input to the control unit 6c, and the control unit 6c changes the separation distance L to the appropriate range according to the extrusion speed V based on this specific data and the advance data determined in advance. This makes it possible to more reliably control the separation distance L to the appropriate range, even when manufacturing the rubber member S using unvulcanized rubber R of various specifications.

As shown in FIG. 4, a belt conveyor 5b can be used as the drawing means 5. This embodiment differs from the previous embodiment only in the drawing means 5, and the rest of the configuration is essentially the same. Like the rotary drive roller 5a in the previous embodiment, this belt conveyor 5b is also controlled to change the separation distance L according to the extrusion speed V. When the belt conveyor 5b is used, the contact area with the rubber member S is larger than that of the rotary drive roller 5a, so the rubber member S can be restrained more stably.

In the embodiment of the manufacturing device 1 illustrated in Figures 5 and 6, the drawing means 5 has multiple rotary drive rollers 5a arranged in a vertical line. This embodiment differs from the previously described embodiment only in the drawing means 5, and the other configurations are essentially the same. Each rotary drive roller 5a is disposed at a height position at the placement level where the rubber member S is placed. Each rotary drive roller 5a can be moved up and down by a variable drive unit 6a such as a fluid cylinder. In this embodiment, the distance L is between the rotary drive roller 5a on which the rubber member S is placed and which is disposed closest to the die 3, and the die 3.

In this embodiment, the separation distance L is changed by moving at least one rotation drive roller 5a below the placement level by the variable drive unit 6a according to the extrusion speed V. As illustrated in FIG. 7, when the rotation drive roller 5a arranged closest to the die 3 is moved below the placement level, the rotation drive roller 5a next to this rotation drive roller 5a is placed closest to the die 3 with the rubber member S placed thereon, and the separation distance L becomes larger. By moving the rotation drive roller 5a arranged closest to the die 3 and the rotation drive roller 5a next to it (i.e., the two rotation drive rollers 5a arranged on the die 3 side) below the placement level, the separation distance L becomes even larger. To decrease the separation distance L, the opposite operation to that for increasing the separation distance L should be performed.

In this embodiment, the separation distance L does not change steplessly, but changes to a number of preset types based on the arrangement of each of the vertically aligned rotation drive rollers 5a. The number of vertically aligned rotation drive rollers 5a is determined appropriately, but is, for example, about 2 to 5.

The drum body 9 is not limited to a simple cylindrical shape. The outer peripheral surface of the drum body 9 shown in Figures 8 and 9 has the same profile as the inner peripheral surface of the finished tire. An example of a drum body 9 having such a shape is the rigid core described above.

For example, in this drum body 9, the rubber member S is wound in a spiral shape around both widthwise ends of the outer peripheral surface of the rotating drum body 9 to produce an annular rubber member Sc. The rubber member S may be wound directly around the outer peripheral surface of the drum body 9, or it may be wound around the outer peripheral surface of another member (inner liner and carcass layer) that is already wound around the outer peripheral surface of the drum body 9. The rubber member S is wound in a spiral shape around the outer peripheral surface of the drum body 9. In this embodiment, the manufactured annular rubber member Sc becomes a member that forms the tire side portion. A cylindrical rubber member Sc can also be manufactured by winding the rubber member S in a spiral shape around the widthwise center of the rotating drum body 9.

The configurations described in each of the above embodiments can be applied to other embodiments to the extent possible.

REFERENCE SIGNS LIST 1 Rubber member manufacturing apparatus 2 Extruder 2a Cylinder 2b Screw 2c Head 3 Die 4 Extrusion flow path 5 Pull-out means 5a Rotation drive roller 5b Belt conveyor 6 Distance variable mechanism 6a Variable drive section 6b Guide section 6c Control section 7 Support roller 8 Transport conveyor 9 Drum body 9a Slide mechanism S Rubber member Sc Annular (cylindrical) rubber member R Unvulcanized rubber

Claims (7)

A method for manufacturing a rubber member, comprising extruding unvulcanized rubber from a die attached to a front end of an extruder, and drawing a rubber member shaped by the die forward while placing the rubber member on a drawing means disposed in front of the die,
A method for producing a rubber member, comprising changing a distance between the die and the drawing means on which the rubber member is placed in accordance with an extrusion speed of the unvulcanized rubber. The method for manufacturing a rubber member according to claim 1, wherein the drawing means is a rotationally driven roller extending in a direction transverse to the rubber member. The method for manufacturing a rubber member according to claim 1, in which a belt conveyor is used as the drawing means. The method for manufacturing a rubber member according to any one of claims 1 to 3, in which a plurality of the drawer means are arranged vertically, each of the drawer means is positioned at a height position of a placement level on which the rubber member is placed, and at least one of the drawer means is moved below the placement level to change the separation distance. The method for manufacturing a rubber member according to any one of claims 1 to 4, in which the rubber member is spirally wound around the outer peripheral surface of a drum body disposed in front of the drawing means to form a circular ring shape. The method for manufacturing a rubber member according to any one of claims 1 to 5, wherein the appropriate range of the separation distance to be changed according to the extrusion speed for each specification of the unvulcanized rubber is determined in advance as advance data and stored in a control unit, and specific data specifying the specification of the unvulcanized rubber is input to the control unit, and the control unit changes the separation distance to the appropriate range according to the extrusion speed based on the specific data and the advance data. An apparatus for manufacturing a rubber member, comprising: an extruder for extruding unvulcanized rubber; and a drawing means disposed in front of a die attached to a front end of the extruder, wherein a rubber member formed by shaping the unvulcanized rubber by the die is placed on the drawing means and drawn forward,
a rubber member extrusion means for extruding the rubber member from the die; a rubber member extruding means for extruding the rubber member from the die;