JP7497609B2 - Method and apparatus for manufacturing pneumatic tires - Google Patents

Description

The present invention relates to a method and an apparatus for manufacturing pneumatic tires.

The following Patent Document 1 describes a tire vulcanizer for vulcanizing a raw tire and a method for vulcanizing a raw tire using the tire vulcanizer. The tire vulcanizer includes an upper mold arranged at a tire vulcanization position, a lower mold equipped with a bladder, a moving device for moving the lower mold between a tire supply position and a tire vulcanization position, and a tire supply device for supplying the raw tire to the lower mold. The vulcanization method includes first mounting the raw tire held by the tire supply device to the lower mold arranged at the tire supply position. Next, the tire supply device is removed from the raw tire. Then, the moving device moves the raw tire and the lower mold to the tire vulcanization position and sets them on the upper mold. Finally, the bladder of the lower mold is inflated to vulcanize the raw tire.

JP 2004-122407 A

In order to vulcanize and mold a tire with precision, it is necessary to properly inflate the bladder. However, unexpected bladder expansion can occur due to misalignment between the bladder and the raw tire, or the bladder expanding without completely smoothing out wrinkles when folded. In such cases, the vulcanized tire may have wrinkles in the bladder on the inner cavity surface of the tire, rubber may protrude from the bead toe (L/TO), and uniformity may deteriorate, resulting in a deterioration in tire quality.

The present invention was devised in consideration of the above-mentioned circumstances, and its main objective is to provide a method and device for manufacturing pneumatic tires that can improve tire quality.

The present invention is a method for manufacturing a pneumatic tire, which includes the steps of inserting a bladder through a bead opening of a green tire placed outside a vulcanization mold and initially inflating the bladder within the tire cavity, setting the green tire together with the initially inflated bladder in the vulcanization mold, and, after closing the vulcanization mold, further inflating the initially inflated bladder to press the green tire against the vulcanization mold.

The method for manufacturing a pneumatic tire according to the present invention preferably includes a step of holding the raw tire with a loader, and the holding step is preferably performed prior to the initial inflation step.

The method for manufacturing a pneumatic tire according to the present invention preferably includes a step of removing the loader from the raw tire, and the removing step is preferably performed prior to the setting step.

The method for manufacturing a pneumatic tire according to the present invention includes a step of controlling the amount of expansion of the bladder that is initially inflated within the tire cavity, and the controlling step is preferably performed prior to the removing step.

In the method for manufacturing a pneumatic tire according to the present invention, it is preferable that the control step includes a step of measuring the amount of expansion of the bladder.

In the method for manufacturing a pneumatic tire according to the present invention, it is preferable that the control step includes a step of adjusting the expansion state of the bladder.

The present invention is a manufacturing device for pneumatic tires, comprising a lower mold, an upper mold positioned at a distance from the lower mold, a moving tool, and a control tool, the lower mold having a molding surface that holds a green tire lying horizontally from below, and a bladder that can be expanded within the cavity of the green tire through a bead opening of the green tire placed on the molding surface, the moving tool moves the lower mold or the upper mold so that the lower mold and the upper mold come into contact with each other to form a vulcanization space for the green tire, and the control tool initially expands the bladder within the tire cavity of the green tire placed on the lower mold prior to the movement of the lower mold or the upper mold by the moving tool.

It is preferable that the pneumatic tire manufacturing apparatus according to the present invention further includes a loader that holds the raw tire sideways from above.

In the pneumatic tire manufacturing apparatus according to the present invention, it is preferable that the loader includes a measuring device for measuring the amount of expansion of the initially inflated raw tire.

In the pneumatic tire manufacturing device according to the present invention, it is preferable that the measuring tool is a non-contact displacement meter.

The manufacturing method and manufacturing device for pneumatic tires of the present invention can improve tire quality by adopting the above configuration.

1 is a cross-sectional view that illustrates a schematic diagram of a manufacturing apparatus used in a method for manufacturing a pneumatic tire according to the present invention. 1A is a flowchart of the present embodiment, FIG. 1B is a flowchart of the holding step of FIG. 1A, and FIG. 1C is a flowchart of the control step of FIG. FIG. 4 is a cross-sectional view of a manufacturing apparatus, which is a schematic diagram showing a second holding step of the present embodiment. FIG. 2 is a cross-sectional view of a manufacturing apparatus, which is a schematic diagram showing an initial expansion step of the present embodiment. 1 is a cross-sectional view of a vulcanizing device, which illustrates a removal process of the present embodiment. FIG. 5A to 5C are cross-sectional views of a manufacturing apparatus, which are schematic diagrams illustrating a setting step and a pressing step of the present embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The method for manufacturing a pneumatic tire of the present invention (hereinafter, sometimes simply referred to as the "manufacturing method") includes a step of forming a raw tire T (shown in FIG. 1) and a vulcanization step of vulcanizing the formed raw tire T. A well-known method is adopted for the step of forming the raw tire T (hereinafter, sometimes simply referred to as the "raw tire forming step"), and therefore a detailed description thereof will be omitted.

Figure 1 is a cross-sectional view conceptually illustrating one embodiment of a pneumatic tire manufacturing device (hereinafter, sometimes simply referred to as "manufacturing device") 1 used in the vulcanization process of this embodiment. The manufacturing device 1 of this embodiment includes a vulcanization mold 2, a moving tool 3, and a control tool 4. The manufacturing device 1 may also include, for example, a loader 5.

In this embodiment, the raw tire T moves sideways in the manufacturing device 1 and is set in the vulcanization mold 2. In this specification, the term "sideways" refers to a direction in which the tire axial direction of the raw tire T is vertical. As a result, as shown in FIG. 1, the sideways raw tire T is divided into a first portion T1, a second portion T2, and a third portion T3. The first portion T1 is, for example, a portion that is radially outward of the maximum width position (not shown) of the tire after vulcanization. The second portion T2 is, for example, a portion that is radially inward and above the first portion T1. The third portion T3 is, for example, a portion that is radially inward of the first portion T1 and below the second portion T2. The raw tire T also includes an upper bead opening T4 formed on the inner side of the second portion T2 in the tire radial direction, and a lower bead opening T5 formed on the inner side of the third portion T3 in the tire radial direction. The upper bead opening T4 and the lower bead opening T5 include the tire rotation axis Tc of the raw tire T. In the figure, the vertical direction is indicated by the arrow Z.

The vulcanization mold 2 of this embodiment includes a lower mold 7 and an upper mold 8 positioned at a distance from the lower mold 7. In this embodiment, the lower mold 7 and the upper mold 8 abut against each other (as shown in FIG. 6). The lower mold 7 and the upper mold 8 abut against each other to form a vulcanization space K for vulcanizing the raw tire T. In this specification, the term "abutment" refers to two objects that can be separated coming into contact with each other.

In this embodiment, the lower mold 7 has a molding surface (hereinafter sometimes referred to as the "lower molding surface") 9 that holds the green tire T lying horizontally from below, and a bladder 10 that can expand within the tire cavity (hereinafter sometimes simply referred to as the "cavity") of the green tire T placed on the molding surface 9. The bladder 10 is made of a well-known elastic material such as rubber.

The lower mold 7 also has, for example, a bagwell 11 of known structure for accommodating the bladder 10. In this embodiment, the bagwell 11 is connected to a supply line (not shown) for supplying a pressurized medium consisting of a known high-pressure fluid such as steam or an inert gas. The pressurized medium is supplied to the bagwell 11, causing the bladder 10 to expand.

The lower mold 7 includes, for example, a lower segment 12 that forms the lower molding surface 9, and a lower plate 13 that is disposed below the lower segment 12. The lower segment 12 includes, for example, a heating tool (not shown) for vulcanizing the third portion T3 of the raw tire T. The lower segment 12 and the lower plate 13 have, for example, an opening for holding the bagwell 11. In this embodiment, the lower plate 13 is fixed to the lower base plate 14. In this manner, the lower mold 7 of this embodiment is configured to have a well-known structure.

The upper die 8 of this embodiment is disposed above the lower die 7. The upper die 8 includes, for example, a molding surface (hereinafter, sometimes referred to as "upper molding surface") 16 that covers the top and sides of the green tire T in a horizontal position. The upper die 8 includes, for example, a separable upper segment 17 that forms the upper molding surface 16, and an upper plate 18 disposed above the upper segment 17. The upper segment 17 includes, for example, a heating tool (not shown) for heating the first portion T1 and the second portion T2 of the green tire T. The upper plate 18 is held, for example, by a first moving tool 20 described later so that it can be raised and lowered. In this way, the upper die 8 of this embodiment is configured with a known structure.

The moving tool 3 in this embodiment is for moving the lower mold 7 or the upper mold 8 so as to form a vulcanization space K for the raw tire T. The moving tool 3 in this embodiment includes a first moving tool 20 for moving the upper mold 8 and a second moving tool 21 for moving the lower mold 7. Note that the moving tool 3 is not limited to this embodiment, and may be composed of only the first moving tool 20, for example.

The first moving device 20 in this embodiment moves the upper mold 8 up and down (vertically). In this embodiment, the first moving device 20 includes a support shaft 20a that holds the upper plate 18 and moves it up and down. Such a first moving device 20 is formed with a well-known structure such as a ball screw or an expandable cylinder structure.

In this embodiment, the second moving device 21 moves the lower mold 7 in the horizontal direction. The second moving device 21, for example, moves the lower base plate 14 linearly toward a position below the upper mold 8 (hereinafter, sometimes referred to as the "vulcanization position A"). Such a second moving device 21 is formed, for example, with a well-known structure such as a ball screw or an expandable cylinder structure.

The loader 5 of this embodiment has a function of moving the raw tire T formed in the raw tire forming process and mounting it on the lower mold 7. The loader 5 is composed of, for example, a horizontal base plate 24 and a plurality of arm parts 25 protruding downward from the base plate 24. In this embodiment, the base plate 24 is held so as to be movable in three dimensions by a moving tool of a known structure (not shown). The arm part 25 has, for example, a bead holding tool 25a of a known structure that holds the second part T2. In this embodiment, the arm part 25 holds the second part T2 from the upper bead opening T4. In this way, the loader 5 of this embodiment can move the raw tire T while suspending it. Note that the loader 5 is not limited to such an embodiment, and may have, for example, a holding tool (not shown) of a known structure for holding the raw tire T on the molding surface 9 of the lower mold 7.

In this embodiment, the loader 5 also has a measuring tool 27 that measures the amount of expansion of the bladder 10 expanding within the tire cavity (in this embodiment, the initial expansion amount, which will be described later). The measuring tool 27 is fixed to the substrate 24, for example. In this embodiment, the measuring tool 27 is preferably a non-contact type displacement meter. More preferably, the measuring tool 27 is, for example, a laser displacement meter that measures distance by irradiating a laser to the object to be measured. Such a measuring tool 27 can output, for example, measurement data d relating to the distance to the object to be measured as an electrical signal.

The control tool 4 is configured as, for example, a computer. The control tool 4 has, for example, a memory for storing measurement data d, etc., a CPU (Central Processing Unit) for performing various arithmetic processing and information processing, etc., a storage device such as a magnetic disk, a display unit for displaying processing results, etc., and an operation unit for operating the measuring tool 27. For example, a program, etc. is stored in advance in the storage device. In this embodiment, the program has a function of initially expanding the bladder 10 in the tire cavity of the raw tire T placed on the lower mold 7 before the lower mold 7 or the upper mold 8 is moved by the moving tool 3. The program may have, for example, a function of controlling the amount of expansion of the bladder 10 or a function of controlling the amount of heat applied to the vulcanization mold 2. The function of controlling the amount of expansion of the bladder 10 may be possessed by, for example, the measuring tool 27.

Next, the vulcanization process of the manufacturing method using such a manufacturing device 1 will be described. FIG. 2(a) is a flowchart of the vulcanization process. As shown in FIG. 2(a), the vulcanization process of this embodiment includes an initial expansion process S2, a setting process S5, and a pressing process S6. The vulcanization process also includes, for example, a holding process S1, a control process S3, and a removal process S4.

Figure 2(b) is a flow chart of the holding step S1. As shown in Figure 2(b), the holding step S1 of this embodiment includes a first holding step S1a in which the raw tire T is held by the loader 5, and a second holding step S1b in which the raw tire T held by the loader 5 is further held by the lower mold 7. Figure 1 shows the first holding step S1a.

As shown in FIG. 1, in the first holding step S1a, in this embodiment, the second portion T2 of the raw tire T is held by the bead holder 25a of the loader 5. As a result, the raw tire T is held in a suspended state on the loader 5 and can be moved in three dimensions.

Next, the second holding step S1b is performed. FIG. 3 is a cross-sectional view illustrating the second holding step S1b. As shown in FIG. 3, in the second holding step S1b of this embodiment, the lower mold 7 is moved by the second moving tool 21 to a position horizontally separated from the upper mold 8 (hereinafter, sometimes referred to as the "raw tire receiving position B"). Then, in the second holding step S1b, the raw tire T held by the loader 5 is moved to the raw tire receiving position B. Then, for example, the loader 5 is lowered, and the third portion T3 of the raw tire T is held on the lower molding surface 9. As a result, in this embodiment, the raw tire T is held by the loader 5 and the lower mold 7.

Next, the initial expansion step S2 is performed. FIG. 4 is a cross-sectional view illustrating the initial expansion step S2. As shown in FIG. 4, in the initial expansion step S2, first, the pressurized medium is supplied from the supply line (not shown) into the bagwell 11, and the bladder 10 is inserted from the lower bead opening T5 to expand in the tire cavity. In the initial expansion step S2, the raw tire T is visible. Therefore, even if the raw tire T is displaced due to the expansion of the bladder 10, it can be easily repositioned to the correct position. In addition, such expected expansion can eliminate wrinkles caused by the bladder 10 being accommodated in the bagwell 11. As a result, for example, unexpected expansion of the bladder 10 that occurs in the vulcanization mold 2 can be suppressed. Therefore, the manufacturing method of this embodiment can improve tire quality. It is desirable that the pressure P1 of the pressurized medium in such an initial expansion step S2 is, for example, 30 KPa or less.

Next, the control step S3 is performed. FIG. 2(c) is a flowchart of the control step S3. As shown in FIG. 2(c), the control step S3 of this embodiment includes a step S3a of measuring the amount of expansion of the bladder 10 and a step S3b of adjusting the expansion state of the bladder 10.

As shown in FIG. 4, in the measurement step S3a in this embodiment, the expansion amount X of the bladder 10 that is initially expanded in the raw tire T is measured. In the measurement step S3a in this embodiment, the expansion amount X is measured by the measuring device 27. The expansion amount X is measured, for example, as the vertical distance between the substrate 24 and the bladder 10 exposed from the upper bead opening T4. When a laser displacement meter is used as the measuring device 27, for example, measurement data d relating to the measured expansion amount X is converted into an electrical signal and output to the control device 4.

The amount of expansion X is preferably measured, for example, at a plurality of predetermined positions on the bladder 10. The amount of expansion X is preferably measured, for example, including positions on the tire rotation axis Tc. The amount of expansion X may be measured, for example, at equal intervals in the circumferential direction of the raw tire T, centered on the tire rotation axis Tc.

In the adjustment step S3b, for example, the expansion state of the bladder 10 is adjusted based on the measured expansion amount X. In this embodiment, in the adjustment step S3b, the control device 4 controls the supply amount of the pressurized medium using an opening/closing valve (not shown) or the like provided in the supply line, and adjusts the expansion amount of the bladder 10 so that the expansion amount X is within a predetermined range. This allows the bladder 10 to be initially expanded evenly within the inner cavity of the raw tire T. In addition, the raw tire T can be positioned appropriately with respect to the molding surface 9.

Next, the removal step S4 is performed. FIG. 5 is a cross-sectional view illustrating the removal step S4. As shown in FIG. 5, in the removal step S4 of this embodiment, the loader 5 is removed from the raw tire T. In this removal step S4, the state in which the lower mold 7 holds the raw tire T is maintained, and the initial expansion of the bladder 10 is maintained. In the removal step S4, the loader 5 is moved away from the raw tire receiving position B, for example, to receive a new raw tire (not shown) formed in the raw tire forming step. In the removal step S4, for example, the second moving tool 21 is driven to move the lower mold 7 and the raw tire T from the raw tire receiving position B to the vulcanization position A. At this time, since the raw tire T is held by the initially expanded bladder 10, positional deviation from the lower mold 7 due to this movement is suppressed.

Next, the setting step S5 is performed. FIG. 6 is a cross-sectional view illustrating the setting step S5 and the pressing step S6. As shown in FIG. 6, in the setting step S5 of this embodiment, the raw tire T is set in the vulcanization mold 2 together with the initially inflated bladder 10. In the setting step S5, for example, the upper mold 8 is lowered by the first moving tool 20, and the raw tire T is set in the vulcanization space K between the upper mold 8 and the lower mold 7. In the setting step S5 of this embodiment, the lower segment 12 and the upper segment 17 come into contact with each other to form a sealed vulcanization space K.

Next, the pressing step S6 is performed. In the pressing step S6 of this embodiment, the initially inflated bladder 10 is further inflated to press the raw tire T against the vulcanization mold 2. The vulcanization mold 2 is then heated by the heating tool (not shown) to vulcanize the raw tire T. The pressure P2 of the pressurizing medium in the pressing step S6 is preferably 1.0 MPa or more and 2.0 MPa or less when the pressurizing medium is steam, and is preferably 1.5 MPa or more and 2.5 MPa or less when the pressurizing medium is nitrogen gas.

The above describes in detail a particularly preferred embodiment of the present invention, but the present invention is not limited to the illustrated embodiment and can be modified and implemented in various ways.

A raw tire was vulcanized using a manufacturing device having the basic structure of FIG. 1, and the tire quality was tested on the vulcanized tire (hereinafter referred to as "vulcanized tire"). The tire quality was confirmed by an appearance test, a uniformity test, and a dynamic balance test. In the comparative example, the raw tire was vulcanized in the same manner as in the example, except that the initial expansion process and the control process of this embodiment were not performed. In both the example and the comparative example, 5,000 raw tires were used, and the average value was calculated for each test.

<Appearance test>
The tester visually checked the occurrence of wrinkles caused by the bladder attached to the inner surface of the vulcanized tire. The results are shown as the percentage of tires that have wrinkles. The smaller the number, the better.

<Uniformity test>
RFV (radial force variation) and LFV (lateral force variation) were measured using a uniformity tester in accordance with JASO C607 (uniformity test method for automobile tires). The results are expressed as an index with the comparative example being 100. The smaller the value, the better.

<Dynamic balance test>
The dynamic balance was measured using a dynamic balance tester. The results are expressed as an index with the comparative example being 100. The smaller the index, the better. The test results are shown in Table 1.

It can be seen that the vulcanization method of the embodiment produces better tire quality than the vulcanization method of the comparative example.

2 Vulcanization mold 10 Bladder S2 Initial expansion process S5 Setting process S6 Pressing process T Green tire

Claims (10)

A method for manufacturing a pneumatic tire, comprising:
A step of inserting a bladder through a bead opening of a green tire placed outside a vulcanization mold and initially expanding the bladder within a cavity of the tire;
placing the green tire together with the initially inflated bladder in a vulcanization mold;
and after closing the vulcanization mold, further inflating the initially inflated bladder to press the green tire against the vulcanization mold ,
controlling an amount of expansion of the initially inflated bladder within the tire cavity;
the controlling step includes a step of measuring an expansion amount of the bladder;
The step of measuring the expansion amount of the bladder is performed by irradiating the bladder with a laser.
A method for manufacturing a pneumatic tire. holding the green tire with a loader;
The method for manufacturing a pneumatic tire according to claim 1 , wherein the holding step is performed prior to the initial inflation step. removing the loader from the green tire;
The method for manufacturing a pneumatic tire according to claim 2 , wherein the removing step is performed prior to the setting step. The method for manufacturing a pneumatic tire according to claim 3 , wherein the controlling step is performed prior to the removing step. The method for manufacturing a pneumatic tire according to claim 1 , wherein the expansion amount is measured at a plurality of predetermined positions of the bladder. The method for manufacturing a pneumatic tire according to claim 1 , wherein the amount of expansion is measured including a position on a tire rotation axis. The method for manufacturing a pneumatic tire according to claim 1 , wherein the expansion amount is measured at equal intervals in a circumferential direction of the raw tire around a tire rotation axis . A pneumatic tire manufacturing apparatus comprising:
The mold includes a lower mold, an upper mold spaced apart from the lower mold, a moving tool, and a control tool,
The lower mold has a molding surface that holds a green tire lying sideways from below, and a bladder that can be inflated within a cavity of the green tire through a bead opening of the green tire placed on the molding surface,
the moving tool moves the lower mold or the upper mold so that the lower mold and the upper mold come into contact with each other to form a vulcanization space for the raw tire,
the control tool initially inflates the bladder in the tire cavity of the green tire placed on the lower mold before the lower mold or the upper mold is moved by the moving tool,
The tire further includes a loader that holds the green tire from above in a horizontal position,
The loader includes a measuring tool that irradiates the bladder with a laser to measure the amount of expansion of the initially expanded bladder.
Pneumatic tire manufacturing equipment. The pneumatic tire manufacturing apparatus according to claim 8 , wherein the measuring tool is a non-contact type displacement meter . 10. The pneumatic tire manufacturing apparatus according to claim 9 , wherein the measuring tool is a displacement meter that measures at equal pitches in the circumferential direction of the raw tire around a tire rotation axis .

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