JP6753281B2 - Pneumatic tire manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a pneumatic tire.

In the process of obtaining a low cover for a tire, a strip of unvulcanized rubber is wound over a drum or rigid core. As a result, tire components such as sidewalls and treads are formed.

An extruder and a calendar roll are used to form the strips. The extruder comprises a cylindrical cylinder and a screw located within the cylinder. As the screw rotates, the unvulcanized rubber charged into the cylinder is pushed out from the tip of the cylinder. The calender roll forms a strip of unvulcanized rubber extruded from the extruder. A strip of strip is delivered from the calendar roll. Studies on devices for forming strips are disclosed in JP-A-2014-54804 and JP-A-2016-2712.

JP-A-2014-54804 JP-A-2016-2712

Extruder screws wear out with use. Worn screws need to be built up or replaced. Conventionally, the gap between the inner surface of the cylinder of an extruder and the screw has been measured in order to control the degree of wear of the screw. This measurement was time consuming and costly.

An object of the present invention is to provide a management method capable of easily controlling the wear amount of a screw.

The present invention is a method for controlling the degree of wear of the screw in an extruder for extruding a rubber composition by rotating a screw and a strip forming machine for a tire including a calender roll for molding the rubber composition and sending out strips. Regarding. This method includes a step of measuring the width of the strip, a step of adjusting the rotation speed of the screw and the surface speed of the calendar roll so that the width of the strip becomes a predetermined value, and the adjusted screw rotation speed. Includes a step of determining the degree of wear of the screw from the relationship between the surface speed and the surface speed of the calendar roll.

Preferably, the degree of wear of the screw of the extruder is determined from the fluctuation of the relationship between the screw rotation speed and the surface speed of the calendar roll over time.

The present invention is an apparatus for managing the degree of wear of the screw in an extruder for extruding a rubber composition by rotating a screw and a strip forming machine for a tire including a calender roll for forming the rubber composition and sending out strips. Regarding. This device includes a width measuring device that measures the width of the strip, a controller that adjusts the rotation speed of the screw and the surface speed of the calender roll so that the width of the strip becomes a predetermined value, and the adjusted screw. A monitoring device for determining the degree of wear of the screw of the extruder is provided based on the relationship between the rotation speed and the surface speed of the calender roll.

When the screw wears, the amount of rubber extruded from the extruder per unit time decreases, even if the rotation speed of the screw is constant. If the surface speed of the calender roll (ie, the speed at which the strip is delivered from the calender roll) is constant, the width of the strip will be narrow. That is, when the screw wears, it is necessary to increase the rotation speed of the screw with respect to the surface speed of the calendar roll in order to send out a strip having a constant width. The inventors came up with the technical idea of controlling the degree of screw wear using this relationship.

The screw wear degree management method according to the present invention includes a step of adjusting the surface speed of the calendar roll and the rotation speed of the screw so that the width of the strip becomes a predetermined value, and the adjusted screw rotation speed and the calendar roll. It includes a step of determining the degree of wear of the screw from the relationship with the surface speed. In this management method, the degree of screw wear is controlled from the relationship between the surface speed of the calender roll and the rotation speed of the screw. With this control method, it is not necessary to measure the clearance between the inner surface of the cylinder of the extruder and the screw to control the degree of wear of the screw. With this management method, it is easy to control the degree of wear of the screw. With this management method, the wear degree of the screw can be managed in a short time and at low cost.

FIG. 1 is a schematic view showing a part of a tire manufacturing apparatus for a management method according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II of the extruder of FIG. FIG. 3A is a graph showing the relationship between the screw rotation speed of the extruder of FIG. 1 in the standby mode and the surface speed of the calendar roll, and FIG. 3B is a screw rotation of the extruder in the operating mode. It is a graph which showed the relationship between the speed and the surface speed of a calendar roll. FIG. 4 is a graph showing the temporal change of the proportional coefficient between the rotation speed of the screw and the surface speed of the calendar roll.

Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

FIG. 1 is a schematic view showing a part of a tire manufacturing apparatus 2 for a management method according to an embodiment of the present invention. In this figure, a strip forming machine 4, a width measuring device 6, a controller 8, an alarm device 10, a monitoring device 12, and a drum 14 are shown. As will be described later, this manufacturing apparatus 2 has a function of controlling the degree of wear of the screw of the strip forming machine 4. The width measuring device 6, the controller 8, and the monitoring device 12 constitute a “screw wear degree management machine”.

The strip forming machine 4 forms a strip made of an unvulcanized rubber composition. The strip forming machine 4 includes an extruder 16 and a pair of calendar rolls 18.

The extruder 16 includes a cylinder 20 and a screw 22. The cylinder 20 has a cylindrical shape. Although not shown, a charging port is provided near the rear end of the cylinder 20 (near the right end in FIG. 1) for charging the rubber composition used as the material for the strip into the cylinder 20. The screw 22 is located in the cylinder 20. The screw 22 can rotate. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. A small gap 24 is provided between the screw 22 and the inner surface of the cylinder 20 so that the screw 22 can rotate in the cylinder 20. The rotation of the screw 22 pushes the rubber composition in the cylinder 20 out of the tip of the cylinder 20.

The pair of calendar rolls 18 are located on the downstream side of the extruder 16. These calendar rolls 18 rotate in the direction of arrow A in FIG. By this rotation, the rubber composition extruded from the extruder 16 is passed between these calendar rolls 18. As a result, the rubber composition is rolled and formed into a strip shape. The strip-shaped strip 26 is sent out from the calendar roll 18. The strip 26 has a predetermined thickness and width. The thickness of the strip 26 is, for example, about 1 mm. The width of the strip 26 is, for example, about 20 mm.

The width measuring device 6 measures the width of the strip 26 sent out from the calendar roll 18. The measured width of the strip 26 is sent to the controller 8. The width measuring instrument 6 is typically a width sensor. For example, a laser width sensor is used.

The width value of the strip 26 is sent from the width measuring instrument 6 to the controller 8. The controller 8 is connected to the strip forming machine 4. The controller 8 can control the rotation speed of the screw 22 of the extruder 16 (hereinafter referred to as the screw rotation speed). The controller 8 can control the speed of the surface of the calendar roll 18 (hereinafter referred to as the surface speed of the calendar roll) by controlling the rotation speed of the calendar roll 18. The surface speed of the calender roll is the speed at which the strip 26 is sent out. That is, the controller 8 can control the speed at which the strip 26 is sent out from the calendar roll 18.

Here, the controller 8 controls the screw rotation speed and the calendar roll surface speed so that the width of the strip 26 becomes a predetermined value. For example, when the width of the strip 26 is smaller than a predetermined width, the controller 8 increases the screw rotation speed of the extruder 16. The amount of rubber composition extruded from the extruder 16 per unit time increases. This increases the width of the strip 26. When the width of the strip 26 is larger than the predetermined width, the controller 8 slows down the screw rotation speed. This reduces the width of the strip 26.

The alarm 10 is connected to the controller 8. The alarm device 10 issues an alarm when, for example, the width of the strip 26 or the screw rotation speed exceeds a predetermined range.

The monitor 12 is connected to the controller 8. In FIG. 1, the monitor 12 is connected to the controller 8 via the network 28. This network 28 is, for example, a LAN in a factory. The network 28 may be a LAN in a factory or the Internet connected to the LAN. The monitoring device 12 may be connected to the controller 8 by a dedicated line. In this embodiment, a plurality of controllers 8 are connected to one monitoring device 12. In this embodiment, the monitoring device 12 includes a display unit 30, a data processing unit 32, a storage unit 34, and an input unit 36. The data processing unit 32 and the storage unit 34 are integrated. The monitoring device 12 is, for example, a personal computer. In the monitor 12, the screw rotation speed and the calendar roll surface speed adjusted by the controller 8 can be confirmed. The ratio of these velocities can be calculated. By storing these values in the storage unit 34, it is possible to confirm the change in the ratio of these speeds over time.

The drum 14 is located downstream of the strip forming machine 4. The drum 14 rotates in the direction of arrow B in FIG. The strip 26 delivered from the strip forming machine 4 is wound on the drum 14. As a result, tire components such as sidewalls and treads are formed.

In the following, a method of manufacturing a tire by the manufacturing apparatus 2 will be described.

In this manufacturing method, the strip 26 is first prepared. The rubber composition used as the material for the strip 26 is charged into the cylinder 20 of the extruder 16. The controller 8 rotates the screw 22 and the calender roll 18. The controller 8 rotates the calendar roll 18 so that the strip 26 is delivered at a low speed. For example, the controller 8 rotates the calendar roll 18 so that the surface speed of the calendar roll is about 100 mm / sec. At the same time, the controller 8 rotates the screw 22 so that the width of the strip 26 becomes a predetermined value at this surface speed. The initial value of this screw rotation speed is determined based on past achievements and the like. As a result, the strip 26 is sent out from the strip forming machine 4 at a set speed.

The width of the delivered strip 26 is measured by the width measuring device 6. The measured width is sent to the controller 8. As described above, the controller 8 controls the screw rotation speed so that the width of the strip 26 becomes a predetermined value.

The strip 26 is conveyed to the drum 14. The end of the strip 26 is placed on the drum 14. The drum 14 rotates and the strip 26 begins to wind on the drum 14.

The controller 8 increases the calendar roll surface velocity when the strip 26 begins to be wound onto the drum 14. For example, the surface speed of the calendar roll is accelerated to about 1000 mm / sec in about 3 seconds. The controller 8 also increases the screw rotation speed. The initial value of this screw rotation speed is determined based on past achievements and the like. For some time after the screw rotation speed changes, the amount of unvulcanized rubber extruded from the extruder 16 may not be stable. The controller 8 controls the screw rotation speed from the measured value of the width of the strip 26 so that this width becomes constant. The control of the screw rotation speed is usually performed within a range of ± 20% or less of the speed before the change.

The strip 26 is wound on the drum 14 to form a tire component. For example, a tread is formed. When the formation of the components is completed, the controller 8 returns the calendar roll surface speed to a low speed. The surface speed of the calender roll is reduced to about 100 / sec. The controller 8 also slows down the screw rotation speed. The controller 8 receives the value from the width measuring device 6 and controls the calendar roll surface speed and the screw rotation speed so that the width of the strip 26 becomes a predetermined value.

As described above, when the strip 26 is not wound around the drum 14, the calendar roll surface velocity is low. The surface speed of the calendar roll is about 100 mm / sec. This state of the strip forming machine 4 is referred to as a standby mode. When the strip 26 is wound around the drum 14, the calendar roll surface speed is high. As described above, the surface speed of the calendar roll is about 1000 mm / sec. This state is called an operating mode.

The tire components formed on the drum 14 are combined with other components. As a result, a low cover can be obtained. The low cover is placed in a mold and heated and pressurized. As a result, the rubber undergoes a cross-linking reaction to obtain a tire.

The manufacturing apparatus 2 of FIG. 1 includes a strip forming machine 4, a width measuring device 6, a controller 8, an alarm device 10, and a drum 14 as one set, and includes a plurality of these sets. The manufacturing apparatus 2 includes a set S1, a set S2, and a set S3. In this embodiment, the device can manufacture multiple tires in parallel. When it is not necessary to manufacture multiple tires in parallel, the device may include one set.

As described above, the manufacturing apparatus 2 has a function of controlling the degree of wear of the screw 22. In the following, a method of controlling the degree of wear of the screw 22 by the manufacturing apparatus 2 will be described.

FIG. 3A is a graph showing the relationship between the calendar roll surface speed and the screw rotation speed when the strip 26 having a constant width is sent out in the standby mode (calender roll surface speed up to about 100 mm / sec). is there. In this graph, the relationship between the calender roll surface speed and the screw rotation speed is shown for the rubber 1 strip 26 and the rubber 2 strip 26. As shown in the figure, in the standby mode, the calendar roll surface speed of the rubber 1 and the screw rotation speed are in a substantially direct proportional relationship. That is, when the surface speed of the calendar roll of the rubber 1 is x1_w and the screw rotation speed of the rubber 1 is y1_w, these relationships are expressed by the following equations.
y1_w = c1_w × x1_w
Here, c1_w is a proportional coefficient. Similarly, in the standby mode, the calendar roll surface speed of the rubber 2 and the screw rotation speed are in a substantially direct proportional relationship. That is, when the surface speed of the calendar roll of the rubber 2 is x2_w and the screw rotation speed of the rubber 2 is y2_w, these relationships are expressed by the following equations.
y2_w = c2_w × x2_w
Here, c2_w is a proportional coefficient.

FIG. 3B is a graph showing the relationship between the calendar roll surface speed and the screw rotation speed when the strip 26 having a constant width is sent out in the operation mode (calender roll surface speed is around 1000 mm / sec). is there. In this graph, the relationship between the calender roll surface speed and the screw rotation speed is shown for the rubber 1 strip 26 and the rubber 2 strip 26. As shown in the figure, in the operation mode, the calendar roll surface speed of the rubber 1 and the screw rotation speed are in a substantially direct proportional relationship. That is, when the surface speed of the calendar roll of the rubber 1 is x1_a and the screw rotation speed of the rubber 1 is y1_a, these relationships are expressed by the following equations.
y1_a = c1_a × x1_a
Here, c1_a is a proportional coefficient. Similarly, in the operation mode, the calendar roll surface speed of the rubber 2 and the screw rotation speed are in a substantially direct proportional relationship. That is, when the surface speed of the calendar roll of the rubber 2 is x2_a and the screw rotation speed of the rubber 2 is y2_a, these relationships are expressed by the following equations.
y2_a = c2_a × x2_a
Here, c2_a is a proportional coefficient.

The above-mentioned proportional coefficient representing the relationship between the calender roll surface speed and the screw rotation speed serves as a guideline for the degree of wear of the screw 22 as described later. Here, this proportional coefficient is referred to as a "wear coefficient". In the example of FIG. 3A, the wear coefficient c1_w and c2_w are different. The abrasion coefficient usually depends on the type of rubber on the strip 26. In the example of FIG. 3, the wear degree coefficient c1_w and the wear degree coefficient c1_a are different. The normal wear coefficient is different between the standby mode and the operating mode even for the same strip 26.

As the wear of the screw 22 progresses, the gap 24 between the inner surface of the cylinder 20 of the extruder 16 and the screw 22 becomes larger. As the screw 22 wears, the amount of rubber extruded from the extruder 16 per unit time decreases even if the screw rotation speed is constant. As the wear of the screw 22 progresses, it is necessary to increase the screw rotation speed in order to push out the same amount of rubber. In order to form a strip 26 having a predetermined width at a predetermined calendar roll surface speed, it is necessary to increase the screw rotation speed. That is, as the wear of the screw 22 progresses, the wear degree coefficient increases. As the wear of the screw 22 progresses, the wear degree coefficients c1_w, c1_a, c2_w and c2_a all increase.

FIG. 4 is a graph showing the change of the wear coefficient with time. The horizontal axis is the usage time of the extruder 16. The vertical axis is the wear coefficient. With the passage of time, the screw 22 wears and the wear degree coefficient gradually increases. The wear coefficient c1_w, c1_a, c2_w and c2_a described above all show this tendency.

In this management method, the degree of wear of the screw 22 is controlled by using the relationship between the calendar roll surface speed and the screw rotation speed when the strip 26 having the above-mentioned constant width is sent out.
With this management method,
(1) A step of measuring the width of the strip 26 with the width measuring device 6.
(2) The controller 8 adjusts the screw rotation speed and the calendar roll surface speed so that the width of the strip 26 becomes a predetermined value, and (3) the degree of wear from the adjusted screw rotation speed and the calendar roll surface speed. The step of determining is carried out.

In the step (3) above, the monitoring device 12 is used. For example, there are the following methods for determining the degree of wear of the screw 22 using the monitor 12.
(Method 1) The data processing unit 32 calculates the wear degree coefficient from the screw rotation speed and the surface speed of the calendar roll, and the display unit 30 displays the value. The wear degree of the screw 22 is determined by the value of the wear degree coefficient. For example, the operator determines from the display result whether the wear degree coefficient is within a predetermined upper limit value. The monitor 12 may determine this and display the result.
(Method 2) The data processing unit 32 calculates the wear degree coefficient from the screw rotation speed and the calender roll surface speed, and stores this in the storage unit 34. The change in the abrasion degree coefficient with the passage of time is displayed on the display unit 30. The degree of wear of the screw 22 is determined from the rate of increase in the degree of wear coefficient. For example, the operator determines from the display result whether the rate of increase in the wear coefficient is within a predetermined upper limit value. The monitor 12 may determine this and display the result.
(Method 3) The data processing unit 32 calculates the wear degree coefficient from the screw rotation speed and the calender roll surface speed, and stores this in the storage unit 34. The change in the abrasion degree coefficient with the passage of time is displayed on the display unit 30. The operator determines from the display result whether the rate of increase of the wear coefficient is within a predetermined upper limit value. The monitor 12 may determine this and display the result. Alternatively, it is determined whether the rate of increase of the wear coefficient is not faster than the rate of increase of the wear coefficient of the other extruder 16.

In this management method, as a result of carrying out the steps (1) to (3) described above, for example, when the wear degree coefficient or the increase rate of the wear degree coefficient exceeds these upper limit values, the screw 22 is built up or replaced. Will be done. If it is within the upper limit, the screw 22 will continue to be used. The steps (1) to (3) above are continuously carried out.

The above upper limit value is set based on, for example, past achievements. Alternatively, for some extruders 16, the gap 24 between the screw 22 and the inner surface of the cylinder 20 is actually measured, and the correlation between the wear coefficient and the actual wear of the screw 22 is examined. From this result, the "upper limit value of the wear degree coefficient" and the "upper limit value of the increase rate of the wear degree coefficient", which serve as a guideline for overlaying or replacing the screw 22, are set. Once these upper limits are set, the degree of wear is subsequently determined using these upper limits.

As described above, the wear coefficient differs between the standby mode and the operating mode. The determination of the wear degree of the screw 22 by the above wear degree coefficient is carried out at least one of the wear degree coefficient in the standby mode and the wear degree coefficient in the operating mode.

As described above, the abrasion coefficient differs depending on the type of rubber of the strip 26. The determination of the degree of wear of the screw 22 based on the above degree of wear coefficient is performed for each type of rubber.

In the embodiment of FIG. 1, a plurality of controllers 8 are connected to the monitoring device 12. In this device, the degree of wear of the screws 22 of the plurality of extruders 16 is collectively managed by the monitor 12. For example, the degree of wear of the screws 22 of more than 100 extruders 16 is controlled by the monitor 12.

As described above, in the manufacturing apparatus 2, the width measuring device 6, the controller 8 and the monitoring device 12 are used to control the degree of wear of the screw 22. The width measuring device 6, the controller 8, and the monitoring device 12 realize the wear degree management function of the screw 22. Therefore, as described above, the width measuring device 6, the controller 8, and the monitoring device 12 are also collectively referred to as a “screw 22 wear degree management machine”.

Hereinafter, the effects of the present invention will be described.

The method for controlling the degree of wear of the screw 22 according to the present invention includes a step of adjusting the calendar roll surface speed and the screw rotation speed so that the width of the strip 26 becomes a predetermined value, and the adjusted screw rotation speed and the calendar roll surface. The step of determining the degree of wear of the screw 22 from the relationship with the speed is included. In this management method, the degree of wear of the screw 22 is controlled from the relationship between the surface speed of the calender roll and the rotation speed of the screw. Specifically, the wear degree is managed by the wear degree coefficient calculated from the calendar roll surface speed and the screw rotation speed. In this management method, it is not necessary to measure the gap 24 between the inner surface of the cylinder 20 of the extruder 16 and the screw 22 in order to control the degree of wear of the screw 22. With this management method, it is easy to control the degree of wear of the screw 22. With this management method, the degree of wear of the screw 22 can be managed in a short time and at low cost.

As described above, in this apparatus, it is preferable to determine the degree of wear of the screw 22 from the rate of increase of the degree of wear coefficient over time. By doing so, the degree of wear of the screw 22 can be predicted with high accuracy.

As described above, for some extruders 16, the gap 24 between the screw 22 and the inner surface of the cylinder 20 is actually measured, and the correlation between the rate of increase in the wear coefficient and the actual wear of the screw 22 is investigated. It is more preferable to determine the degree of wear of the screw 22 by the "upper limit value of the wear degree coefficient" or the "upper limit value of the increase rate of the wear degree coefficient" set thereby. By investigating the correlation between the rate of increase in the wear degree coefficient and the actual wear degree, the wear degree of the screw 22 can be predicted more accurately from the wear degree coefficient.

As described above, it is preferable to connect a plurality of controllers 8 to one monitor 12. By doing so, the degree of wear of the plurality of extruders 16 can be collectively managed. For example, the degree of wear of 100 or more extruders 16 can be managed by one monitoring device 12. This management is easy. With this device, the degree of wear of the screw 22 can be controlled in a short time at low cost.

In the manufacturing apparatus 2, the width of the strip 26 is maintained at a predetermined value by the width measuring device 6 and the controller 8. The width of the strip 26 is maintained at a predetermined value in both the standby mode and the operating mode. When shifting from the standby mode to the operating mode, or when shifting from the operating mode to the standby mode, the screw rotation speed changes significantly. The amount of rubber extruded from the extruder 16 can be unstable. In the manufacturing apparatus 2, the width of the strip 26 is maintained at a predetermined value even in such a case. Further, in this device, the width of the strip 26 is maintained at a predetermined value even if the screw 22 of the extruder 16 is worn. This contributes to improving the manufacturing accuracy of the tire components. This contributes to the improvement of tire manufacturing accuracy.

As described above, the wear degree of the screw 22 can be easily controlled by this management method. From this, the superiority of the present invention is clear.

The device described above can be applied to the manufacture of various tires.

2 ... Manufacturing equipment 4 ... Strip forming machine 6 ... Width measuring device 8 ... Controller 10 ... Alarm device 12 ... Monitoring device 14 ... Drum 16 ... Extruder 18.・ ・ Calendar roll 20 ・ ・ ・ Cylinder 22 ・ ・ ・ Screw 24 ・ ・ ・ Gap 26 ・ ・ ・ Strip 28 ・ ・ ・ Network 30 ・ ・ ・ Display 32 ・ ・ ・ Data processing 34 ・ ・ ・ Storage 36 ・・ ・ Input section

Claims (3)

A method for controlling the degree of wear of the screw in an extruder for extruding a rubber composition by rotating a screw and a strip forming machine for a tire provided with a calendar roll for molding the rubber composition and sending out strips.
The process of measuring the width of the strip,
From the step of adjusting the screw rotation speed and the surface speed of the calendar roll so that the width of the strip becomes a predetermined value, and the relationship between the adjusted screw rotation speed and the surface speed of the calendar roll, the screw A method of managing the degree of wear of a screw, which includes a step of determining the degree of wear of the screw. The management method according to claim 1, wherein the degree of wear of the screw of the extruder is determined from the fluctuation of the relationship between the screw rotation speed and the surface speed of the calendar roll over time. A device for controlling the degree of wear of the screw for a strip forming machine for tires including an extruder that extrudes a rubber composition by rotating a screw and a calender roll that forms the rubber composition and sends out strips.
A width measuring instrument that measures the width of the strip,
The controller that adjusts the screw rotation speed and the surface speed of the calender roll so that the width of the strip becomes a predetermined value, and the extruder from the relationship between the adjusted screw rotation speed and the surface speed of the calender roll. A screw wear management machine equipped with a monitor for determining the screw wear.

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