Tire molding mold

Abstract

To provide a tire molding mold capable of preventing deformation of a tire when removing a vulcanized tire from the tire molding mold with a circumferential split opening and closing system, smoothly removing the tire, and maximizing a capacity of a vulcanizer.SOLUTION: There is provided a tire molding mold having a ring-shaped tread molding part 10 which molds a tread surface 1a of a tire 1, wherein the tread molding part 10 is divided into a plurality of segments 11 in a circumferential direction, and opening and closing operations are performed by moving the plurality of segments 11 in a radial direction. The tire molding mold is provided with a pressing member 20 that protrudes more inside in a radial direction than a tread design surface 11a of the segment 11 from gaps between the plurality of segments 11, in response to the movement of the plurality of segments 11 onto radially outward from radially innermost positions.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire molding die (hereinafter also simply referred to as "die") used in the manufacture of tires for automobiles and the like. Specifically, it relates to a tire demolding technique when removing a product tire vulcanized and molded by the tire molding die. Further, the present invention relates to a technique for improving the structure of a tire molding die that can facilitate the removal of a tire from a vulcanizer even for a tire having a tread pattern with a complex design and having a large resistance to removing so-called undercuts when pulling the die out of the rubber on the tire surface.

Background Art

[0002] As a tire molding die used in manufacturing tires for automobiles and the like, there is known a type in which an annular tread molding part for molding the tread surface of a tire is composed of a plurality of segments divided in the circumferential direction. As such a die, there are many types in which a tapered surface is provided on the outer side in the radial direction of the segment, and an annular outer ring having a tapered surface engaging therewith provided on the inner side in the radial direction is arranged on the outer peripheral side thereof, and the die is opened and closed by the vertical movement of this outer ring. For example, the force for vertically moving the outer ring is converted into a force in the radial direction of the segment to perform the opening and closing operation of the die.

[0003] As a prior art related to a tire molding die, for example, in Patent Document 1, a protrusion provided on the outer peripheral edge of the upper die part and the lower die part for molding the side part of the tire, and a protrusion provided above and below the tread die part divided in the circumferential direction for molding the tire tread part are fitted together to prevent the separation of the upper and lower die parts when the pressure of the vulcanizing medium introduced into the tire acts, and to hold the tread die part in the state at the time of mold closing by the holding force of the lifting cylinder to vulcanize the tire. A tire vulcanizing device configured as such is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] FIG. 3 is an explanatory view schematically showing, in a radial cross section, the occurrence state of mold release failure when removing a vulcanized and molded tire from the tire molding die of the circumferential division opening / closing type described above. When removing a vulcanized and molded tire from the tire molding die of the circumferential division opening / closing type, as shown in FIG. 3, (a) a plurality of segments 111 constituting the mold 110 simultaneously move outward in the tire circumferential direction, so that (b) the segments 111 separate from the surface of the tire 1 with which they were in close contact, and the tire 1 can be taken out.

[0006] However, at this time, as shown in FIG. 3(c), the tire 1 is deformed during mold release, and the tire 1 is not released from a part of the plurality of segments 111, in the illustrated example, two segments 111A and 111B, and there is a case where the tire 1 cannot be taken out from the mold 110.

[0007] Therefore, an object of the present invention is to provide a tire molding die that can prevent deformation of the tire when removing a vulcanized and molded tire from the tire molding die of the circumferential division opening / closing type, smoothly remove the tire, and maximize the capacity of the vulcanizer.

Means for Solving the Problems

[0008] When removing a vulcanized and molded tire from the tire molding die, there are generally two peaks of demolding force when peeling off the mold in close contact with the tire from the tire surface, so-called close contact removal, and when pulling out the mold from the rubber portion of the tire surface at the pattern portion of the tread portion corresponding to the groove shape of the tire, so-called undercut removal. Therefore, the removal of the tire is performed in consideration of the peak values of these two demolding forces.

[0009] The deformation of the tire during demolding as shown in Fig. 3(c) is directly considered to be caused by the fact that the two segments 111A and 111B are in a state where they easily adhere to the tire 1, or the demolding force required to remove the adhesion or undercut with the tire 1 in the two segments 111A and 111B has increased. However, as an indirect factor, the external force applied to the mold through the vulcanizer, that is, the axial force by a hydraulic cylinder or the like, is lost due to the deformation of the tire, and it is considered that sufficient demolding force cannot be developed.

[0010] Fig. 4 is an explanatory diagram related to the opening operation of the tire molding mold in the vulcanizer. The opening operation of the mold 110 in the vulcanizer is, as shown in Figs. 4(a) and 4(b), the container axial force Fs by a hydraulic cylinder or the like gives an upward force or upward displacement to the outer ring 121, and this is converted into a radial direction bent by 90 degrees by the inclined surface structure (cam structure) of the outer ring 121 and the segment 111 constituting the mold 110, and is applied to the segment 111 as the mold opening force Frc. However, the demolding force of the tire itself is dominated by the reaction force Frt on the tire side.

[0011] When the tire 1 deforms during demolding, this reaction force Frt on the tire side (the reaction force for the tire 1 to return from the distorted state to a perfect circle) is likely to become very small. Since the container axial force Fs of the vulcanizer is for giving an upward displacement, the same displacement can be given with a small force, resulting in a phenomenon that the power of the vulcanizer cannot be sufficiently transmitted to the tire side. As a result, if the reaction force Frt on the tire side becomes smaller than the external force required to remove the adhesion or undercut of one segment of the segment 111, it is considered that the demolding will end without completion and the tire 1 cannot be taken out.

[0012] From the above viewpoints, as a result of intensive studies by the present inventor, in a tire molding die, by providing a mechanism for pressing the tread surface of a tire radially inward during the opening operation, deformation of the tire 1 can be prevented, and thus it has been found that the tire 1 can be smoothly taken out, leading to the completion of the present invention.

[0013] That is, the tire molding die of the present invention is as follows.

[0014] (1) A tire molding die including an annular tread molding part for molding the tread surface of a tire, the tread molding part being divided into a plurality of segments in the circumferential direction, and the tire molding die performing an opening and closing operation by moving the plurality of segments in the radial direction, characterized in that, as the plurality of segments move from the radially innermost position to the radially outer side, a pressing member that protrudes radially inward from the tread design surface of the segment is provided from the gap between the plurality of segments. Thereby, deformation of the tire when taking out the vulcanized and molded tire can be prevented, and while maximizing the capabilities of the vulcanizer, the tire can be smoothly taken out.

[0015] (2) The tire molding die according to (1), wherein the pressing member is flat and is arranged parallel to the axial direction of the tread molding part. Thereby, a pressing force for suppressing deformation of the tire can be surely applied to the tread surface of the tire, and a pressing member having a strength such that it does not deform during pressing can be obtained.

[0016] (3) The tire molding die according to (1) or (2), wherein the length of the pressing part located radially inward of the pressing member along the axial direction of the tread molding part is 1 / 4 to 2 / 3 of the width of the tire. Thereby, a pressing force for suppressing deformation of the tire can be surely applied to the tread surface of the tire, and a pressing member having a strength such that it does not deform during pressing can be obtained.

[0017] The mold for tire molding according to any one of (1) to (3), comprising the pressing member at three or more positions in the circumferential direction. Thereby, the deformation of the tire can be more reliably prevented.

[0018] The mold for tire molding according to (4), comprising the pressing member at equal intervals in the circumferential direction. Thereby, the deformation of the tire can be even more reliably prevented.

[0019] (6) As a drive mechanism for moving the plurality of segments in the radial direction, an annular outer ring is provided on the outer side in the radial direction of the segment, and a cam member fixed to the outer ring and protruding inward in the radial direction of the outer ring is provided. The pressing member is disposed on the inner side in the radial direction of the cam member so as to be engageable with the cam member. The mold for tire molding according to any one of (1) to (5), wherein the outer ring moves relative to the segment along a tapered surface provided on the outer side in the radial direction of the segment, thereby moving the segment and the pressing member in the radial direction. Thereby, by only a slight improvement in the structure, the deformation of the tire when taking out the vulcanized and molded tire can be prevented, and the tire can be easily taken out. Without a major modification of the vulcanizer main body, a mold capable of corresponding to a tire having a tread pattern with a complicated design can be obtained.

[0020] (7) The cam member and the pressing member each have a protruding portion protruding radially opposite to each other. As the outer ring moves relative to the segment, the positions of the pair of protruding portions in the axial direction of the tread molding portion overlap, so that the pressing member moves inward in the radial direction. The mold for tire molding according to (6). Thereby, a specific embodiment for moving the pressing member inward in the radial direction as the segment moves outward in the radial direction is shown.

Advantages of the Invention

[0021] According to the present invention, with the above configuration, when taking out the vulcanized tire from the tire molding die of the circumferential direction divided opening and closing type, deformation of the tire can be prevented, the tire can be easily taken out, and a tire molding die capable of maximizing the capabilities of the vulcanizer can be realized.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 2E

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Figs. 1(a) to 1(d) are explanatory diagrams schematically showing the tire deformation prevention process in the tire molding die of the present invention in the radial cross section.

[0024] The tire molding die of the present invention includes an annular tread molding part 10 for molding the tread surface 1a of the tire 1, and the tread molding part 10 is divided into a plurality of segments 11 in the circumferential direction, which is a so-called circumferential divided opening and closing type tire molding die. By moving the plurality of segments 11 in the radial direction, the opening and closing operation is performed.

[0025] Here, the tire 1 is formed mainly of a rubber composition and a reinforcing material, has a tread part that contacts the road surface, and a pair of sidewall parts and bead parts that extend inward in the tire radial direction, and is formed in a shape having a space filled with a gas such as air or nitrogen inside. The tire molding die of the present invention vulcanizes and molds an unvulcanized green tire into the tire 1.

[0026] As shown in the figure, the tire molding die of the present invention is characterized in that as the plurality of segments 11 move from the innermost position in the radial direction to the outside in the radial direction, a pressing member 20 that protrudes radially inward from the tread design surface 11a of the segment 11 is provided from the gap between the plurality of segments 11.

[0027] That is, in the present invention, after the vulcanization molding of the tire 1 is completed, in a state where the plurality of segments 11 are at the innermost position in the radial direction, that is, from the state where the mold is closed (Fig. 1(a)), as the plurality of segments 11 move radially outward and the mold gradually opens, even if the demolding of the tire 1 from some of the segments 11A and 11B is delayed (Fig. 1(b)), since the pressing member 20 protrudes radially inward beyond the tread design surface 11a of the segment 11 from the gap between the segments 11 (Fig. 1(c)), the tread surface 1a of the tire 1 can be pressed radially inward by the pressing member 20. As a result, an external force can be applied to the tire 1 so that the tire 1 returns to a perfect circle, and thus, until the mold is completely opened, the tire 1 can be surely demolded from all the segments 11 (Fig. 1(d)). Therefore, according to the mold of the present invention, deformation of the tire 1 can be prevented and the tire 1 can be maintained in a perfect circle, so that the tire 1 can be taken out easily and smoothly. Also, since the reduction of the reaction force on the tire side is suppressed, the power of the vulcanizer can be sufficiently transmitted from each segment to the tire side, and the ability of the vulcanizer can be maximally exerted. Further, the present invention also has the advantage that it can be implemented by making a minor improvement to the structure of the mold (container) without requiring a large-scale modification of the vulcanizer main body. Furthermore, according to the present invention, it is possible to manufacture even tire types having a special tread pattern that is difficult to demold by making the most of the capabilities of existing vulcanizers. Therefore, in this regard as well, the significance of the present invention can be said to be extremely great.

[0028] In the mold of the present invention, the pressing member 20 may be provided as a separate member from the plurality of segments 11, whereby the intended effect of the present invention can be obtained.

[0029] Regarding the specific shape of the pressing member 20, there is no particular limitation as long as it can press the tread surface of the tire 1 to suppress the deformation of the tire 1. Since the pressing member 20 presses the tire 1 disposed inside the mold from the gaps between the plurality of segments 11 formed along with the opening operation of the mold, it can have a shape such as a flat plate shape, a round bar shape, or a square bar shape that can be inserted into the mold from this gap. In particular, the pressing member 20 is preferably in a flat plate shape and is arranged parallel to the axial direction of the tread molding portion 10. The pressing member 20 needs to be able to apply a pressing force for suppressing the deformation of the tire 1 by pressing the tread surface 1a of the tire 1 and have a strength such that it does not deform during pressing. Therefore, it is preferable that the pressing portion located on the inner side in the radial direction of the pressing member 20 and contacting the tread surface 1a of the tire 1 has a certain contact area. For example, the pressing member 20 can be formed by arranging a plurality of round bars or square bars extending parallel to the radial direction of the tread molding portion 10 in the axial direction for the pressing portion that presses the tread surface 1a of the tire 1.

[0030] Regarding the specific dimensions of the pressing member 20, there is no particular limitation. However, it is preferable that the length of the pressing portion located on the inner side in the radial direction of the pressing member 20 and contacting the tread surface 1a of the tire 1 along the axial direction of the tread molding portion 10 is 1 / 4 to 2 / 3 of the width of the tire 1. By setting the length of the pressing portion of the pressing member 20 along the axial direction of the tread molding portion 10 within this range, it is possible to apply a sufficient pressing force for suppressing the deformation of the tire 1 to the tread surface 1a of the tire 1 and ensure a strength such that it does not deform during pressing.

[0031] Also, regarding the length of the pressing portion of the pressing member 20 along the radial direction of the tread forming portion 10, it suffices if it can protrude radially inward from the tread design surface 11a of the segment 11 beyond the gap between the segments 11 formed with the opening operation. From the viewpoint of surely suppressing the deformation of the tire 1, for example, the pressing portion of the pressing member 20 preferably protrudes 10 to 50 mm radially inward with reference to the surface located most inward in the radial direction of the tread forming portion 10 among the tread design surfaces 11a of the segment 11. In particular, in the case of a passenger car type tire, it preferably protrudes 10 to 20 mm, and in the case of a truck / bus type tire, it preferably protrudes 15 to 40 mm.

[0032] Regarding the length of the pressing portion of the pressing member 20 along the circumferential direction of the tread forming portion 10, it suffices if it can be inserted into the mold from the gap between the segments 11 formed with the opening operation.

[0033] There is no particular limitation on the specific material of the pressing member 20, and it can be the same as other members constituting the mold. For example, steel materials or high-strength resin materials can be used.

[0034] Regarding the number of arrangement positions of the pressing member 20 in the circumferential direction, there is no particular limitation as long as it can prevent the deformation of the tire 1 and can surely demold the tire 1 from the segment 11. Specifically, the number of arrangement positions of the pressing member 20 in the circumferential direction is preferably three or more, and can be equal to or less than the number of divisions of the tread forming portion 10, that is, the number of segments 11. Thereby, the deformation of the tire 1 can be more surely prevented. Also, from the viewpoint of more surely preventing the deformation of the tire 1, it is also preferable that the pressing members 20 are arranged at equal intervals in the circumferential direction.

[0035] The pressing member 20 projects radially inward toward the inside of the mold from the gap between the plurality of segments 11 as the mold opens, pressing the tread surface 1a of the tire 1. After the tire 1 returns to a perfect circle, it can move radially outward again during the period from when the mold 10 finishes opening and the demolding is successfully completed until the mold 10 starts to open, and return to the position before the opening operation of the mold 10 (Fig. 1(d)).

[0036] Figs. 2A to 2E are partial cross-sectional views in the axial direction of a tire molding mold according to an embodiment of the present invention. Fig. 2A shows the state where the mold 100 is closed, Figs. 2B to 2D show the state where the mold 100 is opening, and Fig. 2E shows the state where the mold 100 is fully opened. The illustrated tire molding mold 100 includes an annular tread molding portion 10 for molding the tread surface of the tire 1, and a pair of upper and lower sidewall molding portions 30A and 30B.

[0037] The plurality of divided segments 11 constituting the tread molding portion 10 are composed of a design molding portion 12 and a holder 13 for holding the same. A tread design surface 11a for molding the outer peripheral surface of the tread surface 1a of the tire 1 is formed on the radially inner side thereof, and a tapered surface 11b is formed on the radially outer side thereof.

[0038] In the illustrated mold 100, as a drive mechanism for moving the plurality of segments 11 in the radial direction, an annular outer ring 40 is disposed on the radially outer side of the segment 11, and a tapered surface 40a is formed on the radially inner side thereof, which is in slidable contact with the tapered surface 11b of the segment 11. Further, near the lower end of the outer ring 40, a cam member 50 protruding radially inward of the outer ring 40 is fixed, and a pressing member 20 is disposed on the radially inner side of the cam member 50 so as to be engageable with the cam member 50.

[0039] With such a configuration, as will be described in detail below, the outer ring 40 moves relative to the segment 11 along the tapered surface 11b provided on the radially outer side of the segment 11, thereby enabling the segment 11 and the pressing member 20 to move radially. Therefore, according to the mold 100 of such an embodiment, by only making a minor improvement to the structure, it is possible to prevent the deformation of the tire when taking out the vulcanized tire and easily take out the tire, and it is possible to handle a tire having a tread pattern with a complex design without significantly modifying the vulcanizer main body.

[0040] In the illustrated example, the segment 11 has a tapered surface 11b on its outer peripheral surface facing the radially outer side, which slopes upward so that the outer diameter gradually decreases. On the other hand, the outer ring 40 has a tapered surface 40a on its inner peripheral surface facing the radially inner side, which slopes upward so that the outer diameter gradually decreases. The outer ring 40 is connected to each segment 11 by a guide member (not shown) or the like so that the tapered surface 40a slides vertically along the tapered surface 11b of the segment 11. Further, an elastic member such as a spring (not shown) is disposed between each segment 11 and the lower sidewall molding portion 30B, and each segment 11 is biased radially outward by the corresponding elastic member.

[0041] In the illustrated example, the pressing member 20 is also biased radially outward by an elastic member 60 made of a spring. In the illustrated example, the pressing member 20 has a pressing portion 20a with a substantially rectangular cross section with rounded corners that protrudes radially inward at a position corresponding to the tread surface 1a of the tire 1 in the axial cross section of the tread molding portion 10, and the tread surface 1a of the tire 1 is pressed by this pressing portion 20a. Further, the illustrated pressing member 20 has an inclined portion 20b that inclines upward from the radially outer side toward the radially inner side in the axial cross section of the tread molding portion 10, a rising portion 20c that extends upward from the upper end of the inclined portion 20b, and a protruding portion 20d with a substantially triangular cross section with a tip formed in an R shape that protrudes radially outward from the upper end of the rising portion 20c. As illustrated, the pressing portion 20a and the protruding portion 20d are formed at positions overlapping in the height direction.

[0042] On the other hand, the cam member 50 has a protruding portion 50a that protrudes radially inward and has a substantially triangular cross section with a tip formed in an R shape in the illustrated example. Since the cam member 50 needs to engage with the pressing member 20, its thickness can be made equal to that of the pressing member 20.

[0043] FIG. 2A shows a state where the mold 100 is closed. In this state, the outer ring 40 is located at the lowest position in the axial direction of the tread molding portion 10, and the plurality of segments 11 are located at the innermost position in the radial direction. Further, the pressing member 20 engages with a cam member 50 fixed to the outer ring 40 and is held radially outside the tread design surface 11a of the segment 11.

[0044] In the illustrated example, the cam member 50 and the pressing member 20 each have protruding portions 50a and 20d that protrude radially opposite to each other. As the outer ring 40 moves relative to the segment, the cam member 50 fixed to the outer ring 40 also moves, so that the relative position between the protruding portion 50a of the cam member 50 and the protruding portion 20d of the pressing member 20 in the axial direction of the tread molding portion 10 changes.

[0045] Figure 2B shows the state immediately after the opening operation of the mold 100 starts. From the state of Figure 2A, when the upper sidewall forming portion 30A is driven by a driving portion (not shown) such as a hydraulic cylinder and relatively moves upward with respect to the lower sidewall forming portion 30B, the outer ring 40 starts to relatively move upward on one axial side of the tread forming portion 10 with respect to each segment 11 while sliding the tapered surface 40a along the tapered surface 11b of the segment 11.

[0046] Along with this, the segment 11 is driven by the outer ring 40 and biased by an elastic member (not shown), and moves radially outward from the radially innermost position along the tapered surface 40a of the outer ring 40. On the other hand, the pressing member 20 engages with a cam member 50 fixed to the outer ring 40, and starts to move radially inward due to the positions of a pair of protruding portions 20d and 50a in the axial direction of the tread forming portion 10 overlapping. That is, in the illustrated example, substantially, the relative movement of the outer ring 40 with respect to the segment 11 moves the segment 11 and the pressing member 20 in the radial direction.

[0047] Figure 2C shows the state after the opening operation of the mold 100 progresses. In this state, the outer ring 40 and the upper sidewall forming portion 30A have further moved upward in the axial direction of the tread forming portion 10.

[0048] Along with this, the segment 11 further moves radially outward along the tapered surface 40a of the outer ring 40. On the other hand, the pressing member 20 engages with the cam member 50 and further moves radially inward. Before and after the tips of a pair of protruding portions 20d and 50a in the axial direction of the tread forming portion 10 overlap, the pressing portion 20a of the pressing member 20 protrudes radially inward from the tread design surface 11a of the segment 11 through the gap between the plurality of segments 11 and presses the tread surface 1a of the tire 1. As a result, the tire 1 returns from the distorted state to a perfect circle, so that the phenomenon that the tire 1 does not separate from the mold 100 can be prevented, and the normal demolding of the tire can be promoted.

[0049] FIG. 2D shows the state after the opening operation of the mold 100 has further progressed. In this state, the outer ring 40 and the upper sidewall molding portion 30A have further moved upward in the axial direction of the tread molding portion 10.

[0050] Accordingly, the segment 11 is urged by an elastic member (not shown) and further moves radially outward along the tapered surface 40a of the outer ring 40, and at this stage, the relative movement with respect to the outer ring 40 is completed. On the other hand, the pressing member 20 has completed the radial movement at this stage, similarly to the segment 11, due to the positions of the pair of protruding portions 20d and 50a in the axial direction of the tread molding portion 10 not overlapping.

[0051] FIG. 2E shows the state after the opening operation of the mold 100 is completed. As shown in the figure, at this stage, from the state shown in FIG. 2D, the outer ring 40 and the upper sidewall molding portion 30A further rise, and the segment 11 also rises and moves to the uppermost position in the axial direction of the tread molding portion 10.

[0052] In this state, the tread molding portion 10 and the sidewall molding portions 30A and 30B are in a completely open state, and the vulcanized and molded tire 1 is normally demolded and can be taken out from the mold 100.

[0053] Thereafter, when vulcanizing and molding the next green tire, as the upper sidewall molding portion 30A moves downward to the original position shown in FIG. 2A with a green tire placed in the mold 100 instead of the vulcanized and molded tire 1, the tread molding portion 10 descends to a position adjacent to the lower sidewall molding portion 30B, the outer ring 40 moves downward with respect to each segment 11, and each segment 11 moves inward in the radial direction. As a result, as shown in FIG. 2A, the tread molding portion 10 and the sidewall molding portions 30A and 30B are closed until they are in a state where vulcanizing and molding of the green tire is possible.

[0054] In the illustrated example, a pair of upper and lower sidewall forming parts 30A and 30B can arrange (accommodate) an annular green tire or tire 1 between the lower sidewall forming part 30B and the upper sidewall forming part 30A in a state where its central axis is coaxial with the central axes of the sidewall forming parts 30A and 30B. The lower sidewall forming part 30B has an upward annular sidewall design surface 31B centered on the central axis, and the outer surface of the sidewall part on one side of the tire (the side facing downward in FIGS. 2A to 2E) can be formed by the sidewall design surface 31B. Similarly, the upper sidewall forming part 30A has a downward annular sidewall design surface 31A centered on the central axis, and the outer surface of the sidewall part on the other side of the tire (the side facing upward in FIGS. 2A to 2E) can be formed by the sidewall design surface 31A. Note that the configuration of the sidewall forming parts 30A and 30B can be changed as appropriate.

[0055] The tread forming part 10 has an annular shape coaxial with the sidewall forming parts 30A and 30B, and is arranged adjacent to the radially outer sides of the upper sidewall forming part 30A and the lower sidewall forming part 30B. The tread forming part 10 is composed of a plurality of segments 11 as described above, and the inner peripheral surface of the segment 11 facing radially inward is a tread design surface 11a that forms the outer peripheral surface of the tread surface 1a of the tire 1.

[0056] As shown in FIG. 1, the segment 11 has an arc shape when viewed from the axial direction of the tread forming part 10, and is combined in the circumferential direction to form the tread forming part 10 which is an annular mold as a whole. In the illustrated example, the tread forming part 10 is divided into nine segments 11 having the same circumferential length. The number of divisions of the tread forming part 10 in the circumferential direction is preferably 7 to 13, but is not particularly limited and can be changed as appropriate.

[0057] The holder 13 that constitutes the segment 11 is a part that is driven radially by the outer ring 40 when the tread molding part 10 is opened and closed. The holder 13 can be formed by cutting a metal block such as low-carbon steel, for example.

[0058] The design molding part 12 that constitutes the segment 11 is a part that constitutes the tread design surface 11a for molding the tread surface 1a of the tire 1. The surface facing the radially inner side constitutes a part divided in the circumferential direction of the tread design surface 11a. The design molding part 12 is disposed on the radially inner side of the holder 13 and is fixed to the holder 13 using fixing members such as bolts (not shown).

[0059] The design molding part 12 can be configured such that a plurality of protrusions (not shown) that protrude substantially along the radial direction toward the radially inner side are provided on the tread design surface 11a. The plurality of protrusions form grooves or sipes, etc. that form a tread pattern on the tread surface 1a of the tire 1 during vulcanization molding. The plurality of protrusions can have various shapes or dimensions (lengths) corresponding to the tread pattern, such as those extending in the tire width direction or those extending in the tire circumferential direction. Note that the configuration may be such that no protrusions are provided on the tread design surface 11a.

[0060] The design molding part 12 is preferably formed by casting a metal material with high thermal conductivity such as an aluminum alloy, for example. In this case, for example, a configuration can be adopted in which protrusions formed in a rib shape or blade shape from a steel material are integrated with the design molding part 12 when the design molding part 12 is cast.

[0061] Furthermore, the tire molding die 100 includes a bladder (not shown) that is disposed inside the green tire and expands when pressurized steam is supplied. Still further, the tire molding die 100 includes a heater (not shown) for heating the tread molding part 10 and the sidewall molding parts 30A, 30B. The installation location of the heater can be set as appropriate.

[0062] The mold 100 of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist thereof.

[0063] For example, in the above embodiment, the holder 13 is provided for each segment 11, and the design molding portion 12 is fixed to the holder 13 and the holder 13 is driven by the outer ring 40. However, the holder 13 and the design molding portion 12 may be integrated.

[0064] When manufacturing a tire using the mold 100 of the present invention, first, with the tread molding portion 10 and the pair of sidewall molding portions 30A and 30B open, a green tire is placed inside the mold 100, and then the tread molding portion 10 and the pair of sidewall molding portions 30A and 30B are closed.

[0065] Next, pressurized steam is supplied to the bladder disposed inside the green tire to expand the bladder, and both sidewall portions of the green tire are pressed against the sidewall design surfaces 31A and 31B of the sidewall molding portions 30A and 30B, respectively, and the tread portion is pressed against the tread design surface 11a of the tread molding portion 10. In this state, the tread molding portion 10 and the pair of sidewall molding portions 30A and 30B are heated by a heater to vulcanize the rubber portion constituting the green tire and mold it into a tire having a predetermined shape. After the molding of the tire is completed, the tread molding portion 10 and the pair of sidewall molding portions 30A and 30B are opened, and the vulcanized-molded tire 1 can be taken out.

Explanation of Reference Numerals

[0066] 1 Tire 1a Tread Surface 10 Tread Molding Portion 11, 11A, 11B, 111, 111A, 111B Segment 11a Tread Design Surface 11b, 40a Tapered Surface 12 Design Molding Portion 13 Holder 20 Pressing Member 20a Pressing part 20b Inclined part 20c Upright part 20d, 50a Protruding part 30A Upper sidewall molding part 30B Lower sidewall molding part 31A Downward sidewall design surface 31B Upward sidewall design surface 40, 121 Outer ring 50 Cam member 60 Elastic member 100, 110 Tire molding die

Claims

1. A tire molding die having an annular tread molding portion for molding a tread surface of a tire, the tread molding portion being divided into a plurality of segments in the circumferential direction, and the plurality of segments being moved in the radial direction to perform an opening and closing operation, characterized in that as the plurality of segments move from the innermost position in the radial direction to the outside in the radial direction, a pressing member that protrudes radially inward from the tread design surface of the segment is provided from a gap between the plurality of segments.

2. The tire molding die according to claim 1, wherein the pressing member is flat and is arranged parallel to the axial direction of the tread molding portion.

3. The tire molding die according to claim 1, wherein the length of the pressing portion located radially inward of the pressing member along the axial direction of the tread molding portion is 1 / 4 to 2 / 3 of the width of the tire.

4. The tire molding die according to claim 1, wherein the pressing member is provided at three or more positions in the circumferential direction.

5. The tire molding die according to claim 4, wherein the pressing members are provided at equal intervals in the circumferential direction.

6. As a drive mechanism for moving the plurality of segments in the radial direction, an annular outer ring is provided on the outside in the radial direction of the segment, and a cam member that is fixed to the outer ring and protrudes radially inward of the outer ring is provided, the pressing member is arranged on the inside in the radial direction of the cam member so as to be engageable with the cam member, and the outer ring moves relative to the segment along a tapered surface provided on the outside in the radial direction of the segment, thereby moving the segment and the pressing member in the radial direction. The tire molding die according to claim 1.

7. The cam member and the pressing member each have a protruding portion that protrudes radially opposite to each other, and as the outer ring moves relative to the segment, the positions of the pair of protruding portions in the axial direction of the tread molding portion overlap, so that the pressing member moves radially inward. The tire molding die according to claim 6.

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