Green case cradle and tire molding device

Abstract

To provide a receiving stand for green cases that can suppress deformation of green cases due to their own weight, and a tire molding machine equipped with the stand.SOLUTION: A receiving stand 30 for green cases has a pedestal 31 on which a cylindrical green case 10 is placed, and a pedestal surface 31a of the pedestal is formed by a convex curved arc surface toward the outer diameter direction of the green case 10. This prevents deformation of the green case 10 due to its own weight and, in turn, prevents deterioration of a rubber member's attachment accuracy.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a receiving stand for temporarily placing a green case and a tire building apparatus equipped with the same. [Background technology]

[0002] A known method for manufacturing pneumatic tires is to mold a green tire (unvulcanized tire) through a primary molding process and a secondary molding process. The primary molding process is a process for molding a cylindrical green case including a carcass ply. The secondary molding process is a process for expanding and deforming the green case into a toroidal shape and combining it with a tread band including a belt ply and tread rubber.

[0003] Patent Document 1 describes a method in which the primary molding process is divided into two stages. In this method, a cylindrical band (a form of a green case) including inner liner rubber, carcass ply, etc. is molded in the first stage. Next, the cylindrical band is transferred from the first stage to the second stage. Then, in the second stage, the cylindrical band is subjected to bead setting, turn-up, and attachment of sidewall rubber, etc., to form the green case.

[0004] Patent Document 2 describes a tire building equipment in which the work in the second stage is further divided into two stages. In this equipment, a stage for attaching sidewall rubber (separate sidewall attachment molding stage) is provided separately from the stage for performing bead setting and turn-up on the cylindrical band. Therefore, after the green case has been bead set and turned up, it is transferred between the stages without the sidewall rubber attached.

[0005] The green cases are transported between stages by a transport means called a transfer. For example, in the tire building equipment described above, the transfer picks up the green cases from the building drum after bead setting and turnup have been completed, and transports them to the next sidewall application building stage. The transported green cases are temporarily placed on a receiving stand. The building drum of the sidewall application building stage picks up the green cases placed on the receiving stand and uses them to apply sidewall rubber.

[0006] Because the green case is less rigid and more flexible than the green tire, the part that comes into contact with the cradle is easily deformed by its own weight while it is placed on the cradle. If the roundness of the green case decreases due to such deformation (i.e., the deviation from a perfect circle increases), the green case will become misaligned or lose its posture relative to the molding device (e.g., the molding drum) that picks it up. As a result, the accuracy of the application of rubber components such as sidewall rubber will decrease, and the tire's balance level (uniformity) may deteriorate. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-240162 [Patent Document 2] International Publication No. 2006 / 048924 Summary of the Invention [Problem to be solved by the invention]

[0008] The present disclosure has been made in consideration of the above-mentioned situation, and its purpose is to provide a green case support that can suppress deformation of the green case due to its own weight, and a tire building device equipped with the same. [Means for solving the problem]

[0009] The green case support of the present disclosure comprises a base on which a cylindrical green case is placed, and the base surface of the base is formed by an arcuate surface that is convexly curved radially outward from the green case.

[0010] The tire building apparatus of the present disclosure also includes the green case receiving stand and a sidewall attachment machine that attaches sidewall rubber to the green case taken from the green case receiving stand. [Brief explanation of the drawings]

[0011] [Figure 1] A half cross-sectional view showing the process of forming a green tire [Figure 2] Schematic diagram showing an example of molding equipment for molding green tires [Figure 3] FIG. 1 is a front view showing an example of a green case cradle according to the present disclosure. [Figure 4] (A) A front view and (B) a plan view of the base of the cradle shown in FIG. 3 [Figure 5] FIG. 10 is a front view of a base provided on a cradle according to a reference example; [Figure 6] Schematic diagram showing a modified example of the base DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a green case cradle and a tire building apparatus according to the present disclosure will be described with reference to the drawings.

[0013] 1 is a half-sectional view schematically showing an example of a green tire molding process. A green tire is molded through a primary molding process in which a cylindrical green case including a carcass ply is molded, and a secondary molding process in which the green case is combined with a tread band. As will be described later, in this embodiment, the primary molding process is divided into three processes: (A) a carcass band molding process, (B) a turn-up process, and (C) a sidewall rubber application process, and each process is carried out in a separate molding stage.

[0014] First, as shown in Fig. 1(A), an inner liner rubber 1, a rim strip rubber 2, and a carcass ply 3 are attached in this order on a forming drum D1 (carcass band forming process). This forms a cylindrical green case 10A that forms the carcass band.

[0015] Next, as shown in Fig. 1(B), the green case 10A is bead set and turned up on the forming drum D2 (turn-up process). Specifically, beads 4 are assembled on both sides of the green case 10A, and the carcass ply 3 is folded back around the beads 4. This forms a cylindrical green case 10B that has been bead set and turned up.

[0016] Next, as shown in FIG. 1(C), the sidewall rubber 5 is attached to the green case 10B in the forming drum D3 (sidewall rubber attaching process). This forms a cylindrical green case 10C to which the sidewall rubber 5 is attached. In this embodiment, the sidewall rubber 5 is formed by winding a rubber member having a predetermined cross-sectional shape around the tire circumferential direction. However, this is not limiting, and the sidewall rubber 5 may also be formed by spirally winding a band-shaped rubber ribbon extruded from an extruder.

[0017] 1(D), the belt plies 6, 7, the tread rubber 8, etc. are applied in this order on the forming drum D4 (tread band forming step), whereby a cylindrical tread band 20 is formed.

[0018] Then, as shown in FIG. 1(E), the green case 10C is deformed into a toroidal shape in the building drum D5 and combined with the tread band 20 disposed radially outward (combining step). This results in the formation of an unvulcanized green tire. The green tire thus formed is then vulcanized and molded using a tire vulcanization mold (not shown) to produce a pneumatic tire.

[0019] As described above, the green case 10 is subjected to the secondary molding process (i.e., the combining process) in the form of green case 10C to which the sidewall rubber 5 is attached. However, depending on the stage in the primary molding process, the green case 10 can also take the form of a cylindrical green case 10A forming a carcass band or the form of a green case 10B to which beads have been set and turned up. In this specification, these are collectively referred to as "green case 10."

[0020] Fig. 2 is a schematic diagram showing a molding facility FA for molding a green tire. This molding facility FA is divided into molding stages S1 to S5 each equipped with a separate molding drum D1 to D5 corresponding to the respective molding steps, namely, a carcass band molding step, a turn-up step, a sidewall rubber application step, a tread band molding step, and a combining step. Each of the molding stages S1 to S5 is provided with a molding device A1 to A5 for carrying out each step, respectively, and is configured to perform a predetermined function. The molding devices A1 to A5 provided in each of the molding stages S1 to S5 can be of conventionally known configurations, such as those disclosed in Patent Documents 1 and 2, without any particular restrictions, and therefore detailed explanations and depictions thereof will be omitted.

[0021] The molding equipment FA is provided with transfers 21 to 23 for transferring the green case 10 and the tread band 20. The transfer 21 transfers the green case 10A molded at the molding stage S1 to the molding stage S2. The transfer 22 transfers the green case 10B molded at the molding stage S2 to the molding stage S3. The transfer 22 also transfers the green case 10C molded at the molding stage S3 to the molding stage S5. The transfer 23 transfers the tread band 20 molded at the molding stage S4 to the molding stage S5. The transfers 21 to 23 can be configured in a conventional manner without any particular restrictions.

[0022] The tire building apparatus A3 arranged on the building stage S3 includes a green case receiving stand 30 (hereinafter simply referred to as "receiving stand 30") on which the green cases 10B transferred from the transfer 22 are placed, and a sidewall application machine 40 that applies sidewall rubber 5 to the green cases 10B retrieved from the receiving stand 30. The sidewall application machine 40 includes a building drum D3 configured to be expandable and contractible, a support unit 41 that supports the building drum D3 so that it can be rotated, and a supply unit 42 that supplies sidewall rubber 5 to the building drum D3. The support unit 41 is provided so that it can move along a moving unit 43 while supporting the building drum D3.

[0023] The axial direction of the green case 10B placed on the receiving stand 30 is oriented in the direction of movement of the forming drum D3 (the up-and-down direction in FIG. 2). When the support part 41 moves, the forming drum D3, which is in a reduced diameter state, is inserted into the green case 10B, and the green case 10B is held in a fitted state by the expanding diameter of the forming drum D3. When the support part 41 returns to its original position and the forming drum D3 is placed in a predetermined position, the sidewall rubber 5 supplied from the supply part 42 is attached to the green case 10B on the forming drum D3. At this time, a pressure roller (not shown) presses the sidewall rubber 5 to make it adhere to the green case 10B.

[0024] The green case 10C formed through the process of attaching the sidewall rubber 5 to the green case 10B (sidewall rubber attaching process) is placed back on the receiving table 30. With regard to the operation of the sidewall attaching machine 40, the procedure for transferring the green case 10C to the receiving table 30 can be the reverse of the procedure for retrieving the green case 10B from the receiving table 30. The green case 10C placed on the receiving table 30 is transported by the transfer 22 to the molding stage S5 and subjected to the secondary molding process (combining process).

[0025] As shown in Figures 3 and 4, the receiving base 30 includes a base 31 on which the cylindrical green case 10B is placed, and a support 32 that supports the base 31. In Figure 3, the outline of the outer circumferential surface of the green case 10B is indicated by a dashed line. The base 31 is formed of a material harder than rubber, for example, a metal material such as steel, but it can also be formed of a non-metallic material such as ceramic, plastic, or fiber-reinforced plastic. The green case 10B is placed on the base 31 with its axial direction oriented horizontally. As mentioned above, the axial direction of the green case 10B is oriented in the direction of movement of the forming drum D3, and the green case 10B is held in place by the expanding diameter of the forming drum D3 (not shown in Figure 3) inserted into it.

[0026] Because the green case 10B has a relatively low rigidity and flexibility, when it is placed on the base 91 shown in Fig. 5(A) or the base 92 shown in Fig. 5(B), its own weight easily causes deformation, such that the contact portions 91a and 92a are crushed flat. If the circularity of the green case 10B decreases due to such deformation (i.e., the deviation from a perfect circle increases), the green case 10B may become misaligned or lose its posture relative to the forming drum D3, causing misalignment (deviation from the center line). As a result, the wrapped sidewall rubber 5 may meander, reducing the accuracy of the application of the rubber material and potentially worsening the balance level (uniformity) of the tire.

[0027] 3 and 4, in this embodiment, the seat surface 31a of the seat 31 is formed as an arcuate surface that curves convexly toward the radially outward direction of the green case 10B. This suppresses deformation of the green case 10B due to its own weight, and ultimately prevents a decrease in the accuracy of application of the sidewall rubber 5. The seat surface 31a extends horizontally, and more specifically, along the axial direction of the green case 10B. The length L31a of the seat surface 31a is set to a dimension that is greater than the width W31a of the seat surface 31a and greater than the axial length of the green case 10B, but is not limited to this.

[0028] The radius of curvature R1 of the base surface 31a, which is an arcuate surface, is set to a dimension corresponding to the radius of curvature R2 of the outer peripheral surface of the green case 10B. It is preferable that the radius of curvature R1 is substantially the same as the radius of curvature R2. However, it is also effective to set the radius of curvature R1 slightly larger than the radius of curvature R2 so that it can be used with green cases 10B of different sizes. In this case, it is preferable that the difference between the radius of curvature R1 and the radius of curvature R2 be 3 inches or less. Therefore, for example, it is conceivable to apply a base 31 having a base surface 31a with a radius of curvature R1 corresponding to 19 inches to a pedestal 30 for placing a green case 10B of 16 to 19 inches.

[0029] In this embodiment, when viewed from the axial direction of the green case 10B (i.e., in FIG. 3 or FIG. 4(A)), a void 33 is formed in the center of the base 31. This reduces the contact area between the highly adhesive green case 10B and the base 31, alleviating adhesion and allowing the green case 10B to be smoothly separated from the receiving base 30. The void 33 is formed at a position where it intersects with a vertical plane VP that passes through the center line CL of the arcuate surface that forms the base surface 31a. The base 31 is composed of a pair of base pieces 31X and 31Y arranged on either side of the void 33. The base piece 31X and the base piece 31Y are arranged symmetrically with respect to the vertical plane VP.

[0030] The pedestal surface 31a of the pedestal piece 31X and the pedestal surface 31a of the pedestal piece 31Y each extend along a single arc centered on a common center line CL. The central angle θ1 of the arc surface forming the pedestal surface 31a is preferably 45 to 75 degrees, and more preferably 50 to 70 degrees. A central angle θ1 of 75 degrees or less is advantageous in reducing adhesion of the green case 10B. Furthermore, a central angle θ1 of 45 degrees or more is advantageous in ensuring the stability of the placed green case 10B. In this embodiment, an example is shown in which the central angle θ is 60 degrees.

[0031] The base surface 31a is preferably positioned below a horizontal plane HP passing through the center line CL of the arcuate surface that forms the base surface 31a. With this configuration, when the green case 10B is placed on the base 31, the side surface of the green case 10B (especially the side surface near the horizontal plane HP) is not pressed against the base surface 31a, so that traces of contact with the base surface 31a are less likely to remain. To achieve this improvement, the angle θ2 formed between the horizontal plane HP and a line connecting the upper end of the base surface 31a to the center line CL is preferably 12.5 degrees or more, and more preferably 15 degrees or more. In this embodiment, an example in which the angle θ2 is 15 degrees is shown.

[0032] The arcuate surface forming the base surface 31a is preferably roughened, which reduces adhesion between the highly adhesive green case 10B and the base 31, allowing the green case 10B to be smoothly separated from the receiving base 30. Examples of the roughening treatment include blasting such as sandblasting.

[0033] In this embodiment, the base 31 is configured to be displaceable in the radial direction of the green case 10B. As shown in FIG. 3, the base 31 is supported by the support 32 via a displacement cylinder 34 (e.g., an air cylinder) serving as an actuator. When the green case 10B is placed on the base 31, the displacement cylinder 34 is extended. Therefore, when the displacement cylinder 34 contracts from this state, the base 31 is displaced radially outward. Since the preferred amount of displacement of the base 31 differs depending on the size of the green case 10B, the amount of contraction of the displacement cylinder 34 can be adjusted by changing the thickness of a stopper 35 attached between the base 31 and the support 32.

[0034] When the green case 10B is removed from the base 31, the forming drum D3 expands in diameter to hold the green case 10B, and the displacement cylinder 34 contracts, displacing the base 31 (base piece 31X and base piece 31Y) radially outward. This separates the base surface 31a from the outer peripheral surface of the green case 10B, allowing the green case 10B to be supported by the forming drum D3 alone. While it is possible to displace the base 31 vertically or horizontally, it is preferable to displace it radially as in this embodiment in order to prevent deformation of the green case 10B when it is separated from the base surface 31a.

[0035] In this embodiment, the configuration of the cradle 30 used to place the green case 10B has been described, but a similar configuration can also be applied to cradles for placing the green case 10A or the green case 10C. Therefore, for example, when a cradle for temporarily placing the green case 10C transferred from the molding stage S3 is arranged in the molding stage S5, the above-described configuration can be applied to the cradle. This suppresses deformation of the green case 10C due to its own weight and prevents a decrease in positioning accuracy during the combining process.

[0036] As described above, the green case holder 30 of this embodiment includes a base 31 on which the cylindrical green case 10B (one example of the green case 10) is placed, and the base surface 31a of the base 31 is formed by an arc surface that is curved convexly toward the radially outward direction of the green case 10B. This configuration suppresses deformation of the green case 10B due to its own weight, and prevents a decrease in the accuracy of attachment of the rubber member (for example, the sidewall rubber 5).

[0037] When viewed from the axial direction of the green case 10B, it is preferable that a void 33 be formed in the center of the base 31. This reduces the contact area between the green case 10B and the base 31, alleviating adhesion and allowing the green case 10B to be smoothly separated from the receiving base 30.

[0038] The central angle of the arcuate surface forming the base surface 31a is preferably 45 to 75 degrees. This configuration is advantageous in terms of reducing adhesion of the green case 10B and ensuring the stability of the placed green case 10B.

[0039] It is preferable that base surface 31a be located below a horizontal plane HP passing through a center line CL of the arcuate surface that forms base surface 31a, thereby making it difficult for traces of contact with base surface 31a to remain on the side surface of green case 10B.

[0040] It is preferable that the arcuate surface forming the base surface 31a is roughened, which reduces the adhesion between the green case 10B and the base 31 and allows the green case 10B to be smoothly separated from the receiving base 30.

[0041] The base 31 is preferably configured to be displaceable in the radial direction of the green case 10 B. This configuration allows the green case 10 B to be smoothly transferred.

[0042] The tire building apparatus A3 of this embodiment also includes a green case receiving stand 30 and a sidewall application machine 40 that applies sidewall rubber 5 to the green case 10B retrieved from the green case receiving stand 30. By including the above-described receiving stand 30, deformation of the green case 10B due to its own weight can be suppressed, and a decrease in the application accuracy of the sidewall rubber 5 can be prevented.

[0043] The receiving base 30 is not limited to the configuration of the above-described embodiment, and is not limited to the above-described effects. Furthermore, various improvements and modifications of the receiving base 30 are possible without departing from the spirit and scope of the present invention. Therefore, for example, the shape of the base 31 may be modified as shown in FIG. 6. FIG. 6(A) shows an example in which a void 33 is not formed in the center of the base 31. FIG. 6(B) shows an example in which the base surface 31a reaches the horizontal plane HP. FIG. 6(C) shows an example in which a void 33 is not formed in the center of the base 31, and the base surface 31a reaches the horizontal plane HP. FIG. 6(D) shows an example in which the center line CL of the arcuate surface forming the base surface 31a of the base piece 31X is misaligned with the center line CL of the arcuate surface forming the base surface 31a of the base piece 31Y. [Explanation of symbols]

[0044] 3 Carcass ply 5 Sidewall rubber 10 Green Case 10A Cylindrical green case forming the carcass band 10B Green case with bead set and turn-up 10C Green case with sidewall rubber attached 30 Green Case Stand 31 Pedestal 31a Pedestal surface 33 Vacant Space 40 Sidewall pasting machine A1~A5 Tire building equipment D1~D5 forming drums S1~S5 molding stages

Claims

1. A base is provided on which the cylindrical green case is placed with its axial direction directed horizontally, The base surface of the base is formed by an arcuate surface that is convexly curved toward the radially outer side of the green case, and is disposed only below a horizontal plane passing through a center line of the arcuate surface, A green case support base having a void formed in the center of the base when viewed in the axial direction of the green case.

2. The green case cradle according to claim 1, wherein the central angle of the arcuate surface is 45 to 75 degrees.

3. The green case cradle according to claim 1 or 2, wherein the arcuate surface is subjected to a roughening treatment.

4. A green case support according to any one of claims 1 to 3, wherein the base is configured to be displaceable in the radial direction of the green case.

5. A green case cradle according to any one of claims 1 to 4, a sidewall attachment machine that attaches sidewall rubber to the green case taken from the green case receiving stand.

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