Method and device for manufacturing pneumatic tire

Abstract

A method for manufacturing a pneumatic tire and a manufacturing device thereof. Improving tire quality. The method for manufacturing a pneumatic tire comprises: a step (S2) of initially inflating an air bladder (10) within the tire cavity of a green tire (T) placed outside a vulcanization mold (2); a step (S5) of placing the green tire (T) and the initially inflated air bladder (10) together in the vulcanization mold (2); and a step (S6) of further inflating the initially inflated air bladder (10) after closing the vulcanization mold (2) to press the green tire (T) against the vulcanization mold (2).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a pneumatic tire and a manufacturing device thereof. Background Art

[0002] Patent Document 1 below describes a tire vulcanizer for vulcanizing a green tire and a method for vulcanizing a green tire using the tire vulcanizer. The tire vulcanizer includes an upper mold positioned at a tire vulcanization position, a lower mold having an air 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 green tire to the lower mold. Furthermore, the vulcanization method includes first attaching the green tire held by the tire supply device to the lower mold positioned at the tire supply position. Next, the tire supply device is removed from the green tire. The moving device then moves the green tire and the lower mold to the tire vulcanization position and places them on the upper mold. Finally, the air bladder of the lower mold is inflated, causing the green tire to be vulcanized.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-122407 Summary of the Invention

[0004] To vulcanize and mold tires with high precision, the bladder must be properly inflated. However, unexpected bladder inflation can occur due to misalignment between the bladder and the green tire, or when the bladder is folded and inflated while the folds are not fully extended. In such cases, the vulcanized tire may not only have bladder wrinkles on the inner surface of the tire or rubber protrusions from the tire bead (L / TO), but also may suffer from poor uniformity, leading to reduced tire quality.

[0005] The present invention is proposed in view of the above actual situation, and its main purpose is to provide a method and apparatus for manufacturing a pneumatic tire that can improve tire quality.

[0006] The present invention is a method for manufacturing a pneumatic tire, which includes the following steps: inserting an air bladder from the bead opening of a green tire placed outside a vulcanization mold to initially inflate the air bladder within the tire cavity; placing the green tire together with the initially inflated air bladder in the vulcanization mold; and after closing the vulcanization mold, further inflating the initially inflated air bladder to press the green tire against the vulcanization mold.

[0007] The method for manufacturing a pneumatic tire of the present invention preferably includes a step of holding the green tire using a loader, wherein the holding step is performed before the initial expansion step.

[0008] The method for manufacturing a pneumatic tire according to the present invention preferably includes a step of removing the loader from the green tire, wherein the removing step is performed before the setting step.

[0009] The method for manufacturing a pneumatic tire of the present invention preferably includes a step of controlling the inflation amount of the airbag during the initial inflation within the tire cavity, wherein the controlling step is performed before the removing step.

[0010] In the method for manufacturing a pneumatic tire according to the present invention, preferably, the step of controlling includes a step of measuring an inflation amount of the airbag.

[0011] In the method for manufacturing a pneumatic tire according to the present invention, preferably, the step of controlling includes a step of adjusting an inflation state of the airbag.

[0012] The present invention is a device for manufacturing pneumatic tires, which includes a lower mold, an upper mold located at a position separated from the lower mold, a moving device and a control device, the lower mold having: a molding surface that holds the green tire in a transverse direction from the lower side; and an air bladder that is capable of expanding in the inner cavity of the green tire through the bead opening of the green tire placed on the molding surface, the moving device moves the lower mold or the upper mold so that the lower mold abuts against the upper mold to form a vulcanization space for the green tire, and before the moving device moves the lower mold or the upper mold, the control device causes the air bladder to initially expand in the tire inner cavity of the green tire placed on the lower mold.

[0013] The pneumatic tire manufacturing apparatus of the present invention preferably further includes a loader that holds the green tire in a lateral direction from above.

[0014] In the pneumatic tire manufacturing apparatus of the present invention, it is preferable that the loader includes a measuring device for measuring an amount of expansion of the green tire after the initial expansion.

[0015] In the pneumatic tire manufacturing apparatus of the present invention, it is preferable that the measuring device is a non-contact displacement meter.

[0016] The pneumatic tire manufacturing method and the pneumatic tire manufacturing apparatus of the present invention can improve tire quality by adopting the above-mentioned structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional view schematically showing a manufacturing apparatus used in the method for manufacturing a pneumatic tire of the present invention.

[0018] Figure 2 (a) is a flow chart of this embodiment, Figure 2 (b) is Figure 2(a) is a flow chart of the holding process, Figure 2 (c) is Figure 2 (a) is a flow chart of the control process.

[0019] Figure 3 It is a cross-sectional view schematically showing the manufacturing apparatus in the second holding step of this embodiment.

[0020] Figure 4 It is a cross-sectional view schematically showing a production apparatus in the initial expansion step of the present embodiment.

[0021] Figure 5 It is a cross-sectional view of the vulcanizing apparatus schematically showing the disassembly step of the present embodiment.

[0022] Figure 6 It is a cross-sectional view schematically showing the manufacturing apparatus in the setting step and the pressing step of the present embodiment.

[0023] Description of labels

[0024] 2: vulcanization mold; 10: airbag; S2: initial inflation process; S5: setting process; S6: pressing process; T: green tire. DETAILED DESCRIPTION

[0025] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0026] The manufacturing method of the pneumatic tire of the present invention (hereinafter, sometimes simply referred to as "manufacturing method") includes forming a green tire T ( Figure 1 The step of forming the green tire T (hereinafter sometimes referred to as the "green tire forming step") adopts a well-known method, and therefore its detailed description is omitted.

[0027] Figure 1 This is a cross-sectional view conceptually illustrating one embodiment of a pneumatic tire manufacturing apparatus (hereinafter sometimes referred to simply as a "manufacturing apparatus") 1 used in the vulcanization process of this embodiment. The manufacturing apparatus 1 of this embodiment includes a vulcanization mold 2, a moving device 3, and a control device 4. Furthermore, the manufacturing apparatus 1 may also include, for example, a loader 5.

[0028] In this embodiment, the green tire T is moved transversely in the manufacturing apparatus 1 and is set in the vulcanization mold 2. In this specification, the "transverse" refers to the direction in which the tire axial direction of the green tire T is vertical. Figure 1As shown, the green tire T is divided into a first portion T1, a second portion T2, and a third portion T3 in the transverse direction. The first portion T1 is, for example, a portion radially outward from the maximum width position of the vulcanized tire (not shown). The second portion T2 is, for example, a portion radially inward from and above the first portion T1. The third portion T3 is, for example, a portion radially inward from the first portion T1 and below the second portion T2. In addition, the green tire T includes an upper bead opening T4 formed radially inward of the second portion T2 and a lower bead opening T5 formed radially inward of the third portion T3. The upper bead opening T4 and the lower bead opening T5 include the tire rotation axis Tc of the green tire T. In the figure, the vertical direction is indicated by the arrow Z.

[0029] The vulcanization mold 2 of this embodiment includes a lower mold 7 and an upper mold 8 located at a position separated from the lower mold 7. In this embodiment, the lower mold 7 and the upper mold 8 are in contact with each other ( Figure 6 As shown in FIG. 7 , the lower mold 7 and the upper mold 8 abut against each other to form a vulcanization space K for vulcanizing the green tire T. In this specification, the term “abut” refers to the collision and contact of two isolable objects.

[0030] In this embodiment, the lower mold 7 includes a molding surface (hereinafter sometimes referred to as the "lower molding surface") 9 that holds the green tire T in a horizontal direction from below, and an air bladder 10 that can be inflated within the tire cavity (hereinafter sometimes referred to simply as the "inner cavity") of the green tire T placed on the molding surface 9. The air bladder 10 is formed of a known elastic material such as rubber.

[0031] The lower mold 7 also includes, for example, a bladder 11 of a known structure for housing the airbag 10. In this embodiment, the bladder 11 is connected to a supply line (not shown) for supplying a pressurized medium such as steam or an inert gas. Supplying the pressurized medium to the bladder 11 inflates the airbag 10.

[0032] The lower mold 7 includes, for example, a lower split mold 12 that forms the lower molding surface 9, and a lower plate 13 disposed below the lower split mold 12. The lower split mold 12 includes, for example, a heating device (not shown) for vulcanizing the third portion T3 of the green tire T. The lower split mold 12 and the lower plate 13 each have an opening for holding the bladder 11. In this embodiment, the lower plate 13 is fixed to the lower base plate 14. As described above, the lower mold 7 of this embodiment has a known structure.

[0033] The upper mold 8 of this embodiment is arranged above the lower mold 7. The upper mold 8 includes, for example, a molding surface (hereinafter sometimes referred to as "upper molding surface") 16 that covers the green tire T in the transverse direction from the upper side and the side. The upper mold 8 includes, for example, a separable upper split mold 17 that forms the upper molding surface 16 and an upper plate 18 that is arranged above the upper split mold 17. The upper split mold 17 includes, for example, a heating device (not shown) for heating the first portion T1 and the second portion T2 of the green tire T. The upper plate 18 is held by, for example, a first movable device 20 described later so as to be movable up and down. As described above, the upper mold 8 of this embodiment is composed of a well-known structure.

[0034] The moving device 3 of this embodiment is used to move the lower mold 7 or the upper mold 8 to form a curing space K for the green tire T. The moving device 3 of this embodiment includes a first moving device 20 for moving the upper mold 8 and a second moving device 21 for moving the lower mold 7. The moving device 3 is not limited to this embodiment and may, for example, consist of only the first moving device 20.

[0035] The first moving device 20 of this embodiment moves the upper mold 8 vertically up and down. In this embodiment, the first moving device 20 includes a support shaft 20a that holds the upper plate 18 and allows it to move up and down. Such a first moving device 20 is formed using a known structure such as a ball screw or a telescopic cylinder.

[0036] The second moving device 21 of this embodiment moves the lower mold 7 horizontally. For example, the second moving device 21 linearly moves the lower base 14 toward a position below the upper mold 8 (hereinafter sometimes referred to as "vulcanization position A"). Such a second moving device 21 is formed using a known structure such as a ball screw or a telescopic cylinder.

[0037] The loader 5 of this embodiment has the function of moving the raw tire T formed in the raw tire forming process and mounting the raw tire T on the lower mold 7. The loader 5 is composed of, for example, a horizontal plane base plate 24 and a plurality of arms 25 protruding downward from the base plate 24. In this embodiment, the base plate 24 is held three-dimensionally by a moving device of a known structure not shown in the figure. The arm 25 has, for example, a bead retaining device 25a of a known structure for retaining the second portion T2. In this embodiment, the arm 25 retains the second portion T2 from the upper bead opening portion T4. In this way, the loader 5 of this embodiment can suspend the raw tire T and move it. In addition, the loader 5 is not limited to such a method. For example, it may also have a retaining device of a known structure (omitted from the figure) for retaining the raw tire T on the molding surface 9 of the lower mold 7.

[0038] Furthermore, in this embodiment, the loader 5 includes a measuring device 27 that measures the amount of expansion (in this embodiment, the initial expansion amount, described later) of the airbag 10 inflated within the tire cavity. The measuring device 27 is, for example, fixed to the base plate 24. In this embodiment, the measuring device 27 is preferably a non-contact displacement meter. More preferably, the measuring device 27 is, for example, a laser displacement meter that measures the distance to the object being measured by irradiating it with laser light. Such a measuring device 27 can, for example, output measurement data d related to the distance to the object being measured as an electrical signal.

[0039] The control device 4 is configured as a computer, for example. The control device 4 includes, for example, a memory for storing measurement data d, a CPU (Central Processing Unit) for performing various computational operations or information processing, a storage device such as a magnetic disk, a display unit for displaying processing results, and an operating unit for operating the measuring device 27. The storage device may, for example, pre-store a program. In this embodiment, the program has the function of initially inflating the airbag 10 within the tire cavity of the green tire T placed on the lower mold 7 before the lower mold 7 or upper mold 8 is moved by the moving device 3. The program may also, for example, control the amount of inflation of the airbag 10 and the amount of heat applied to the vulcanization mold 2. Furthermore, for example, the measuring device 27 may also have the function of controlling the amount of inflation of the airbag 10.

[0040] Next, the vulcanization step of the production method using such a production apparatus 1 will be described. Figure 2 (a) is a flow chart of the vulcanization process. Figure 2 As shown in (a), the vulcanization process of this embodiment includes an initial expansion process S2, a setting process S5, and a pressing process S6. In addition, the vulcanization process includes, for example, a holding process S1, a control process S3, and a disassembly process S4.

[0041] Figure 2 (b) is a flowchart of the maintenance step S1. Figure 2 As shown in (b) of FIG. 1 , the holding step S1 of the present embodiment includes a first holding step S1 a in which the loader 5 holds the green tire T, and a second holding step S1 b in which the lower mold 7 further holds the green tire T held by the loader 5 . Figure 1 The first holding step S1a is shown.

[0042] like Figure 1 As shown, in this embodiment, in the first holding step S1a, the second portion T2 of the green tire T is held by the bead retainer 25a of the loader 5. Thus, the green tire T is held in a suspended state by the loader 5 and is three-dimensionally movable.

[0043] Next, the second holding step S1b is performed. Figure 3 : is a cross-sectional view illustrating the second holding step S1b. Figure 3 As shown, in the second holding step S1b of this embodiment, the lower mold 7 is moved by the second moving device 21 to a position horizontally separated from the upper mold 8 (hereinafter sometimes referred to as the "green tire receiving position B"). Then, in the second holding step S1b, the green tire T held by the loader 5 is moved to the green tire receiving position B. Then, for example, the loader 5 is lowered, and the third portion T3 of the green tire T is held by the lower molding surface 9. Thus, in this embodiment, the green tire T is held by the loader 5 and the lower mold 7.

[0044] Next, the initial expansion step S2 is performed. Figure 4 1 is a cross-sectional view illustrating the initial expansion step S2. Figure 4 As shown, in the initial expansion process S2, the pressurized medium is first supplied to the bladder 11 from the supply line (not shown), and the airbag 10 is inserted from the lower bead opening T5 to expand the airbag 10 in the tire cavity. The raw tire T can be visually observed in the initial expansion process S2. Therefore, even if the raw tire T is displaced by the expansion of the airbag 10, it can be easily reconfigured to the appropriate position. In addition, by such expected expansion, wrinkles and the like caused by the accommodation of the airbag 10 in the bladder 11 can be eliminated. As a result, it is possible to suppress the unexpected expansion of the airbag 10, for example, in the vulcanization mold 2, and therefore, in the manufacturing method of this embodiment, the tire quality can be improved. The pressure P1 of the pressurized medium in such an initial expansion process S2 is preferably, for example, less than 30 kPa.

[0045] Next, the control step S3 is performed. Figure 2 (c) is a flow chart of the control step S3. Figure 2 As shown in (c), the control step S3 of the present embodiment includes a step S3a of measuring the inflation amount of the airbag 10 and a step S3b of adjusting the inflation state of the airbag 10 .

[0046] like Figure 4 As shown, in this embodiment, in the measurement step S3a, the expansion amount X of the airbag 10 initially inflated within the green tire T is measured. In the measurement step S3a of this embodiment, the expansion amount X is measured using the measuring device 27. The expansion amount X is measured, for example, as the vertical distance between the substrate 24 and the airbag 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 related to the measured expansion amount X is converted into an electrical signal and output to the control device 4.

[0047] The inflation amount X is preferably measured at a plurality of predetermined positions on the airbag 10. The inflation amount X is preferably measured including positions on the tire rotation axis Tc. The inflation amount X can be measured at equal intervals in the circumferential direction of the green tire T, centered around the tire rotation axis Tc.

[0048] Adjustment step S3b adjusts the inflation state of the airbag 10, for example, based on the measured inflation amount X. In this embodiment, in adjustment step S3b, the control device 4 controls the supply of pressurized medium via an on / off valve (not shown) provided on the supply line, thereby adjusting the inflation amount of the airbag 10 so that the inflation amount X falls within a predetermined range. This ensures uniform initial inflation of the airbag 10 within the inner cavity of the green tire T. Furthermore, the green tire T can be positioned appropriately relative to the molding surface 9.

[0049] Next, the disassembly step S4 is performed. Figure 5 1 is a cross-sectional view illustrating the disassembly process S4. Figure 5 As shown, in the disassembly step S4 of this embodiment, the loader 5 is removed from the green tire T. During this disassembly step S4, the lower mold 7 is maintained in the state of holding the green tire T, and the initial inflation of the bladder 10 is maintained. During this disassembly step S4, the loader 5 moves away from the green tire receiving position B, for example, to receive a new green tire (not shown) formed in the green tire forming step. During this disassembly step S4, for example, the second moving device 21 is driven to move the lower mold 7 and green tire T from the green tire receiving position B to the vulcanization position A. At this time, the green tire T is held by the initially inflated bladder 10, thereby preventing it from shifting from the lower mold 7 due to this movement.

[0050] Next, the setting step S5 is performed. Figure 6 1 is a cross-sectional view illustrating the setting process S5 and the pressing process S6. Figure 6 As shown, in the setting step S5 of this embodiment, the green tire T is set in the vulcanization mold 2 together with the initially inflated bladder 10. In the setting step S5, the upper mold 8 is lowered by, for example, the first moving device 20, and the green 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 split mold 12 abuts against the upper split mold 17, forming a closed vulcanization space K.

[0051] Next, a pressing step S6 is performed. In the pressing step S6 of this embodiment, the initially inflated bladder 10 is further inflated to press the green tire T against the vulcanization mold 2. Furthermore, the vulcanization mold 2 is heated by the heating device (not shown), thereby vulcanizing the green tire T. The pressure P2 of the pressurized medium in the pressing step S6 is preferably 1.0 MPa or higher and preferably 0.2 MPa or lower when the pressurized medium is steam, and preferably 1.5 MPa or higher and preferably 2.5 MPa or lower when the pressurized medium is nitrogen.

[0052] As mentioned above, although the particularly preferred embodiment of the present invention has been described in detail, the present invention is not limited to the illustrated embodiment, and can be implemented in various modified forms.

[0053] [Example]

[0054] Use with Figure 1 Green tires were vulcanized using a manufacturing apparatus having a basic structure, and the vulcanized tires (hereinafter referred to as "vulcanized tires") were tested for tire quality. Tire quality was confirmed through appearance testing, uniformity testing, and dynamic balance testing. In the comparative example, green tires were vulcanized in the same manner as in the example, except that the initial expansion and control steps of this embodiment were omitted. 5,000 green tires were used in both the example and the comparative example, and the average value was calculated for each test.

[0055] <Appearance test>

[0056] The tester visually inspects the presence of wrinkles caused by air bladders adhering to the inner surface of the vulcanized tire. The results are expressed as a ratio of the number of tires with wrinkles. The smaller the value, the better.

[0057] <Uniformity Test>

[0058] According to JASO C607 (Uniformity Test Method for Automobile Tires), RFV (Radial Force Variation) and LFV (Lateral Force Variation) were measured using a uniformity tester. The results were expressed as an index with the comparative example as 100. The smaller the value, the better.

[0059] <Dynamic balance test>

[0060] Dynamic balance was measured using a dynamic balance tester. The results were expressed as an index, with the comparative example set at 100. Smaller values are better. The test results are shown in Table 1.

[0061]

Table 1

[0062] Comparative Example Example Appearance test (ratio) 100 0 RFV (index) 100 97 LFV(index) 100 88 Dynamic balance (index) 100 94

[0063] It can be understood that the vulcanization method of the embodiment produces a tire of superior quality compared to the vulcanization method of the comparative example.

Claims

1. A method for manufacturing a pneumatic tire, wherein: The process includes the following steps: Inserting an air bladder from a lower bead opening of a green tire placed outside a vulcanization mold to initially inflate the air bladder within an inner cavity of the green tire; placing the green tire together with the initially inflated bladder in a vulcanization mold; and After closing the vulcanization mold, the initially inflated airbag is further inflated to press the green tire against the vulcanization mold. The pneumatic tire manufacturing method includes the step of controlling the inflation amount of the airbag during the initial inflation in the tire cavity of the green tire. The controlling step includes measuring the inflation amount of the airbag during the initial inflation in the tire cavity of the green tire using a measuring device. The step of measuring the inflation amount of the airbag includes irradiating the airbag with laser light to measure the vertical distance between a substrate to which the measuring device is fixed and the airbag exposed from an upper bead opening of the green tire.

2. The method for manufacturing a pneumatic tire according to claim 1, wherein: The pneumatic tire manufacturing method includes the step of holding the green tire using a loader. The maintaining step is performed before the initial expansion step.

3. The method for manufacturing a pneumatic tire according to claim 2, wherein: The pneumatic tire manufacturing method includes the step of removing the loader from the green tire. The disassembly process is performed before the installation process.

4. The method for manufacturing a pneumatic tire according to claim 3, wherein: The controlling step is performed before the disassembling step.

5. The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, wherein: The inflation amount is measured at a plurality of predetermined locations of the airbag.

6. The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, wherein: The amount of expansion is measured including the position of the tire on its axis of rotation.

7. The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, wherein: The expansion amount is measured at equal intervals in the circumferential direction of the green tire with the tire rotation axis as the center.

8. A pneumatic tire manufacturing device, wherein: The pneumatic tire manufacturing device includes a lower mold, an upper mold located at a position separated from the lower mold, a moving device, and a control device. The lower mold has a molding surface that holds the green tire in a horizontal direction from below, and an air bag that is inflated in the inner cavity of the green tire through the lower bead opening of the green tire placed on the molding surface. The moving device moves the lower mold or the upper mold so that the lower mold abuts against the upper mold to form a vulcanization space for the green tire. Before the moving device moves the lower mold or the upper mold, the control device causes the airbag to initially inflate within the tire cavity of the green tire placed on the lower mold. The pneumatic tire manufacturing apparatus further includes a loader for holding the green tire in a lateral direction from above. The loader includes a measuring device for irradiating the airbag with laser light in order to measure the inflation amount of the airbag after the initial inflation, and a base plate for fixing the measuring device. The measuring device measures the vertical distance between the substrate and the bladder exposed from the upper bead opening of the green tire to measure the inflation amount of the bladder initially inflated in the tire cavity of the green tire.

9. The pneumatic tire manufacturing apparatus according to claim 8, wherein: The measuring device is a non-contact displacement meter.

10. The pneumatic tire manufacturing apparatus according to claim 9, wherein: The measuring device is a displacement meter that measures displacement at equal intervals in the circumferential direction of the green tire with the tire rotation axis as the center.

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