JP2004243732A - Rubber layer molding method using variable die head and variable die head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a tire by a variable die head which can deal with various sectional shapes. <P>SOLUTION: This method manufactures a tire by sequentially laminate-winding strip rubbers S to be extrusion-molded from the die head 20 around a molding drum 1. The die head 20 is of a variable die head type which makes the sectional shape of the strip rubber S to be extrusion-molded changeable. In a process to wind the strip rubber S around the molding drum 1, a rubber layer of a desired sectional shape is formed by changing the sectional shape. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rubber layer forming method for manufacturing a rubber layer by sequentially winding and laminating strip rubber extruded from a die head onto a forming drum and a variable die head used for the method.
[0002]
[Prior art]
As a method of forming a rubber layer constituting a tread portion or a sidewall portion of a tire, for example, a method of manufacturing a tread strip disclosed in Japanese Patent No. 2682872 is known. It uses an injector head (corresponding to a die head) to form a substantially trapezoidal tread strip. The cross-sectional shape of the tread strip extruded from the injector head is the same as the cross-sectional shape of the tread layer to be manufactured, and the tread layer is formed by winding the tread strip around the forming drum once.
[0003]
[Patent Document]
Patent No. 2682872 [Problem to be solved by the invention]
When forming a tread portion and other rubber layers, it is important to correspond to rubber layers having various cross-sectional shapes. This is to achieve high-mix low-volume production efficiently. In the above prior art, the injector head is provided with a mechanism for adjusting the thickness and the width, so that the cross-sectional shape can be changed. Thereby, tread portions having different cross-sectional shapes can be realized by one injector head.
[0004]
However, in the above prior art, the cross-sectional shape can be changed, but there is a limit to the shape that can be changed. For example, it can correspond to a simple trapezoidal shape, but it is difficult to correspond to other shapes. It can cope with the formation of a tread layer, but it is difficult to cope with other rubber layers such as sidewalls.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rubber layer forming method capable of responding to various cross-sectional shapes and a variable die head used for the method.
[Means for Solving the Problems]
In order to solve the above problems, a method of forming a rubber layer by a variable die head according to the present invention includes:
A rubber layer forming method for forming a rubber layer by sequentially winding and laminating a strip rubber extruded from a die head onto a forming drum,
The die head is constituted by a variable die head capable of changing the cross-sectional shape of the strip rubber to be extruded. In the step of winding around the forming drum, a rubber layer having a desired cross-sectional shape is formed by changing the cross-sectional shape. It is characterized by the following.
[0006]
The operation and effect of the rubber layer forming method according to this configuration are as follows. When forming a rubber layer such as a tire, a rubber layer is formed by winding and laminating a strip rubber extruded from a die head around a forming drum. This strip rubber has a sectional shape having a smaller sectional area than the sectional shape of the rubber layer to be formed. By sequentially winding such strip rubber, a rubber layer having a desired cross-sectional shape can be formed. Since a strip rubber having an originally small cross-sectional area is used, a desired cross-sectional shape is easily obtained. That is, if the lamination method is changed, rubber layers having different cross-sectional shapes can be obtained. Therefore, it becomes easy to obtain various cross-sectional shapes. Further, a variable die head is used as the die head, and the cross-sectional shape can be changed while the strip rubber is wound around the forming drum. This makes it possible to cope with a finer and more complicated cross-sectional shape. As a result, it is possible to provide a rubber layer molding method using a variable die head that can cope with various cross-sectional shapes.
[0007]
As a preferred embodiment of the present invention, the variable die head has a variable opening dimension in a width direction of the forming drum,
At the start of winding of the strip rubber, control is performed so that the opening dimension in the width direction of the die head is gradually increased from 0,
At the end of the winding of the strip rubber, there is a type in which the opening dimension is controlled so as to gradually become zero.
[0008]
When winding the strip rubber around the forming drum, if the strip rubber having the same sectional shape is wound from the beginning to the end, useless overlap of the strip rubber occurs at the start of winding and at the end of winding. That is, when the strip rubber is wound along the drum axis direction of the forming drum, as shown in FIG. 8, the first winding and the second winding inevitably occur in the region indicated by the hatched line P at the beginning of winding. Further, at the end of the winding, the (n-1) th winding and the nth winding overlap in a region indicated by oblique lines R. Since the overlapping portion is not functionally necessary in many cases, an extra process such as cutting and removing the overlapping portion after the winding process is completed is required.
[0009]
On the other hand, in the present invention, the variable die head has a variable opening dimension in the width direction of the forming drum, and gradually increases the opening dimension in the width direction of the die head from 0 at the start of winding the strip rubber. At the end of the winding, so that the opening size gradually becomes zero. As a result, there is no need to generate useless overlap that occurs at the start and end of the winding.
[0010]
As another preferred embodiment of the present invention, the variable die head has a variable opening dimension in a width direction of the forming drum,
At the start of the winding of the strip rubber, the opening dimension of the die head in the width direction is set to a predetermined dimension,
When sequentially winding and laminating the strip rubber, a tread layer may be formed by controlling the opening dimension in the width direction to be gradually reduced.
[0011]
By such a step, the tread layer can be formed efficiently and accurately. For example, if the cross-sectional shape of the tread layer is trapezoidal, the opening of the die head is set so that the base dimension of the trapezoid becomes a predetermined dimension. Thereafter, by controlling the opening size to be gradually reduced, a tread layer having a desired cross-sectional shape can be obtained.
[0012]
As still another preferred embodiment of the present invention, the variable die head has a variable opening dimension in a width direction and a height direction of the forming drum,
When winding the strip rubber on the inclined area, control the width and height of the opening dimension to be small, and when winding the strip rubber on a flat area, control the opening dimension to increase the width and height. Are characterized by the following.
[0013]
According to this configuration, the shape of the rubber layer in the inclined portion can be accurately molded, and the molding speed of the entire rubber layer can be improved.
[0014]
The variable die head used in the rubber layer forming method according to the present invention is characterized in that the opening size in the width direction and the height direction can be changed. With such a configuration, it is possible to cope with various cross-sectional shapes.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of a tire manufacturing method using a variable die head according to the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing an arrangement relationship between a forming drum and a strip rubber extruder. FIG. 2 is a diagram illustrating the formation of a rubber layer using strip rubber.
[0016]
<Tire manufacturing method using strip rubber>
In FIG. 1, the forming drum 1 is driven to rotate around a drum shaft 1a by a second driving device. Further, a strip rubber extruder 2 (hereinafter, simply referred to as “extruder”) is provided, and is driven in three directions by a first driving device. Specifically, there are a first direction A orthogonal to the drum shaft 1a, a second direction B parallel to the drum shaft 1a, and a third direction C which is a turning direction around a predetermined axis. These three directions can be driven independently of each other, and can be driven by combining appropriate directions. Thereby, the extruder 2 can be moved complicatedly.
[0017]
2A shows, as an example, a cross-sectional shape of a rubber layer to be formed on the outer periphery of the forming drum 1. FIG. In the present invention, this cross-sectional shape is formed by laminating strip rubber S having a small cross-sectional area. As a cross-sectional shape, for example, a triangular shape is given as an example. In this way, by using the strip rubber S, even if the cross-sectional shape of the rubber layer is changed, it is possible to cope with the change without changing the strip rubber S. Further, in order to wind the strip rubber S around the forming drum 1, the die head 20 must be moved corresponding to the cross-sectional shape (profile) of the rubber layer. Therefore, as shown in FIG. 1, the die head 20 of the extrusion device 2 can be moved with a high degree of freedom by allowing the extrusion device 2 to be moved in three directions.
[0018]
FIG. 3 is a side view showing an arrangement relationship between the forming drum 1 and the extruding device 2. The extruder 2 includes a die head 20, a gear pump 21, and a small extruder 22. The die head 20 has a mold portion capable of extruding a strip rubber having a predetermined cross-sectional shape. The gear pump 21 has two gears 21 a and supplies a fixed amount of rubber toward the molding die 20. The small extruder 22 includes a screw 22a and kneads rubber. In FIG. 3, the two gears 21a are vertically arranged for convenience of illustration, but are actually arranged in a plane direction (a direction in which the rotation axis of the gear is vertically).
[0019]
The strip rubber extruded from the extruder 2 is supplied in the direction of arrow D, and is sequentially wound around the outer periphery of the forming drum 1 (direction of arrow E). Further, in order to wind the strip rubber on the forming drum 1, a pressing roller 3 for pressing the strip rubber against the forming drum 1 is provided. The pressing roller 3 can move between a position close to the forming drum 1 and a position separated from the forming drum 1 (in the direction of arrow F).
[0020]
The forming drum 1 is driven to rotate with high precision by a first servomotor 4 (corresponding to a second driving device). The gear pump 21 is also driven to rotate with high precision by the second servomotor 5. Servo motors 4 and 5 are driven so that the strip rubber does not sag from the die head 20 to the forming drum 1. The die head 20 is a variable die head capable of changing the opening size of the opening from which the strip rubber is extruded (this point will be described later). Therefore, a die head driving device 9 for driving the die head 20 is provided.
[0021]
In FIG. 3, a roller driving device 6 for driving the pressing roller 3 is provided. Further, a first driving device 7 for moving the extruding device 2 in three directions A, B, and C shown in FIG. 1 is provided. Further, a control device 8 for controlling the roller driving device 6, the first driving device 7, and the die head driving device 9 is also provided. The control device 8 controls each device based on a control program 10 installed in advance.
[0022]
<Configuration example of variable die head>
In the tire manufacturing method according to the present invention, the cross-sectional shape of the strip rubber extruded from the die head can be changed. FIG. 4 shows a configuration example of the variable die head.
[0023]
In FIG. 4A, the opening is rectangular in cross section, and the short side and the long side can be changed at the same time. Thereby, the size of the rectangle can be changed. (B) is a trapezoidal cross section, and the upper and lower dies can be moved along the oblique sides of the left and right dies. Thereby, the size of the trapezoid can be changed. In (c), the opening is a parallelogram, and the upper and lower dies can be moved along the oblique sides of the left and right dies. Thereby, the size of the parallelogram can be changed. (D) is that the opening is rectangular in section, and differs from (a) in that the upper and lower dies and the left and right dies can be driven independently. Therefore, the configuration is more flexible than (a) in terms of shape changeability. (E) shows that the opening is a parallelogram in cross section and differs from (c) in that the upper and lower dies and the left and right dies can be driven independently. Accordingly, the configuration is more flexible in terms of shape changeability than (c). In FIG. 4, the left-right direction corresponds to the drum axis direction (drum width direction) of the forming drum.
[0024]
Note that the example shown here is one example, and various other configuration examples are conceivable. For example, the cross-sectional shape includes a triangle, a circle, a semicircle, and the like. The drive mechanism for driving the mold can be appropriately selected from a combination of a motor and a ball screw, a hydraulic cylinder, and the like. The opening dimension of the opening is preferably configured such that the dimension in the width direction can be changed in a range of 0 to 50 mm and the dimension in the thickness direction can be changed in a range of 0 to 10 mm. Absent.
[0025]
<Example of forming rubber layer of tire>
Next, a tire manufacturing method using a variable die head will be described. FIG. 5 is a diagram illustrating a winding control in the case where the strip rubber is sequentially wound along the drum axis direction of the forming drum.
[0026]
FIG. 5A shows a state before the start of winding. The die head 20 is provided with a left base 20a and a right base 20b, and is configured to be movable along the drum axis direction. The opening is in a closed state. The forming drum 1 starts rotating along the direction of arrow E in the figure. On the other hand, simultaneously with the operation of pushing out the strip rubber, the right base 20b moves in the direction of the arrow in the figure.
[0027]
As shown in (b), since the strip rubber is extruded while the opening is gradually opened from the closed state, the width of the strip rubber wound around the forming drum 1 also gradually increases. (C) is a state in which the forming drum 1 has just made one rotation. Until the forming drum 1 makes exactly one rotation, the width of the strip rubber gradually increases linearly.
[0028]
As shown in (c), when the forming drum 1 makes one rotation, the movement of the right mouthpiece 20b stops, and thereafter the size of the opening is fixed. On the other hand, at the same time as the forming drum 1 makes one rotation, the forming drum 1 is traversed at the processing speed in the direction of arrow G in the figure. After the forming drum 1 makes one rotation, the strip rubber is gradually wound as shown in (d), and this state is continued until one rotation before the end of winding as shown in (e). Then, the traverse of the forming drum 1 is stopped one rotation before the end of winding. At the same time, the base 20a on the left side of the variable die head 20 is moved rightward in the drawing, and the size of the opening is gradually reduced. As a result, the width of the strip rubber gradually decreases, contrary to the time when the winding is started.
[0029]
(F) is a figure in the state where winding was completed. The rotational drive of the forming drum 1 is stopped, and the opening of the variable die head is completely closed. In this way, by controlling the width of the strip rubber at the start and end of the winding, it is possible to eliminate the useless overlapping portion of the strip rubber as described with reference to FIG. As described above, when a rubber layer is formed by winding a strip rubber having a constant cross-sectional area, useless overlapping is inevitably generated at the start and end of the winding. However, as in the present invention, the cross-sectional shape of the strip rubber is Is variable, it is possible to form a rubber layer having a desired cross-sectional shape without useless overlap.
[0030]
FIG. 5 shows an example of winding a strip rubber. When forming a tread portion or a sidewall portion, a rubber layer is formed by sequentially laminating strip rubbers. Also in the case of sequentially laminating, regarding the control of the width dimension of the strip rubber at the start of winding and at the end of winding, the same concept as in FIG. 5 can be applied. Further, in the embodiment described with reference to FIG. 5, the cross-sectional shape of the opening is fixed in an intermediate step other than the start and end of the winding. Is also good.
[0031]
Next, a method for manufacturing the rubber layer in the tread portion will be described with reference to FIG. At the start of winding, the opening of the variable die head 20 is set to a first dimension D1 (predetermined dimension). From this state, the forming drum 1 starts rotating in the direction of arrow E in the figure, and the size of the opening is gradually reduced. In the case of the shape shown in (c), the width direction of the opening at the end of the winding is the second dimension D2. As compared with the winding method shown in FIG. 2 (b), the number of windings can be reduced, so that the time for forming the rubber layer can be shortened. It is also possible to form a rubber layer having a shape as shown in FIG. As described with reference to FIG. 3, by changing the control program 10 for controlling the die head driving device 9, various controls for the opening can be performed.
[0032]
Next, still another embodiment of the method for forming a rubber layer of a tire will be described with reference to FIG. In this method, the dimensions of the opening of the variable die head in the width direction and the height direction are changed during molding. (A) is a state at the beginning of winding. At both ends 1A in the axial direction of the forming drum 1, the strip rubber SA is wound in a state where the opening is inclined according to the shape of the forming drum 1. At this time, the width and height are controlled to be small. Thereby, the rubber layer can be accurately laminated even on the inclined shape or the curved shape of the both ends 1A in the axial direction of the forming drum 1.
[0033]
(B) shows a state in which the winding process is advanced and the strip rubber SB is wound around a flat area in the center of the forming drum 1. In the flat region, the width dimension and the height dimension can be made larger than before. Thereby, the molding speed of the rubber layer can be increased. (C) is a state in which the winding is further advanced from (b). When the winding is one layer, the rubber layers are finished by winding the strip rubbers SA and SB to the other axial end.
[0034]
In the case of forming into two or more layers, the layers are further wound as shown in (d) and (e). In this way, by controlling the cross-sectional shape of the opening to be changeable during molding according to the shape of the rubber layer, it is possible to cope with rubber layers having various shapes.
[0035]
<Another embodiment>
The rubber layer to which the tire manufacturing method according to the present invention can be applied is not limited to the rubber layer at a specific place. The present invention can be applied to a rubber layer other than the tread portion and the sidewall portion.
[0036]
Further, the present invention is not limited to the technology applicable only to tires, but is also applicable to rubber products (rubber layers) such as air suspensions and tubes (hoses).
[Brief description of the drawings]
FIG. 1 is a plan view showing an arrangement relationship between a forming drum and a strip rubber extruding device. FIG. 2 is a diagram illustrating formation of a rubber layer using strip rubber. FIG. 3 is a side view showing an arrangement relationship between a forming drum and an extruding device. FIG. 4 is a view showing a configuration example of a variable die head; FIG. 5 is a view showing an embodiment of a tire manufacturing method using the variable die head; FIG. FIG. 8 shows a method of forming a rubber layer of a tire according to an embodiment. FIG. 8 shows a method of winding a strip rubber according to a conventional technique.
DESCRIPTION OF SYMBOLS 1 Forming drum 1a Drum shaft 2 Strip rubber extruder 8 Control device 9 Die head drive device 10 Control program 20 Die heads 20a and 20b Die S Strip rubber

Claims (5)

A rubber layer molding method for manufacturing a rubber layer by sequentially winding and laminating a strip rubber extruded from a die head onto a molding drum,
The die head is constituted by a variable die head capable of changing a cross-sectional shape of a strip rubber to be extruded, and in a winding step around the forming drum, a rubber layer having a desired cross-sectional shape is formed by changing the cross-sectional shape. A method for forming a rubber layer using a variable die head, characterized in that: The variable die head has a variable opening dimension in the width direction of the forming drum,
At the start of winding of the strip rubber, control is performed so that the opening dimension in the width direction of the die head is gradually increased from 0,
2. The method according to claim 1, wherein when the winding of the strip rubber is completed, the opening size is controlled so as to gradually become zero. The variable die head has a variable opening dimension in the width direction of the forming drum,
At the start of the winding of the strip rubber, the opening size of the die head in the width direction is set to a predetermined size,
The rubber according to claim 1, wherein the tread layer is formed by controlling the opening size in the width direction to be gradually reduced when the strip rubber is sequentially wound and laminated. Layer forming method. The variable die head is capable of changing an opening dimension in a width direction and a height direction of the forming drum,
When winding the strip rubber on the inclined area, control the width and height of the opening dimension to be small, and when winding the strip rubber on a flat area, control the opening dimension to increase the width and height. The method of claim 1, wherein the rubber layer is formed by a variable die head. A variable die head used in the method for molding a rubber layer with the variable die head according to any one of claims 1 to 4,
A variable die head that can change the opening size in the width and height directions.

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