JP4843435B2 - Pneumatic tire manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire in which a sound absorbing tool made of a foam material is provided on the lumen surface side of a tread portion, and more specifically, a raw material is preliminarily included with a foam material, and this is subjected to a vulcanization step. The present invention relates to a technique capable of integrally forming the sound absorbing tool by foaming by using.

  Conventionally, a pneumatic tire has been proposed in which a sound absorbing tool made of a foam such as sponge is provided on the tire lumen surface side of the tread portion (see, for example, Patent Document 1 below). In such a pneumatic tire, the noise absorption device absorbs cavity resonance generated in the tire lumen surrounded by the tire and the rim, so that road noise during traveling is reduced.

JP 2003-285607 A

  The pneumatic tire described above is formed, for example, by forming a raw tire in which an unfoamed foam material is attached to the inner surface of a lumen, and then expanding the mold and a bladder that expands by being filled with high-temperature and high-pressure fluid. It is manufactured by heating and pressurizing and foaming the foamed material simultaneously with the vulcanization of the raw tire. However, in this method, since the balloon-like bladder is in close contact with the inner surface of the tire, a sufficient volume expansion space for foaming the foamed material cannot be obtained, and as a result, foaming is suppressed or the foamed material is distorted. There is a drawback of swelling.

  After the vulcanization is completed, the mold opens and the high-pressure fluid in the bladder is removed, so that the bladder gradually spontaneously shrinks so that the internal pressure is balanced with the atmospheric pressure. Therefore, when a space capable of expanding the foamed material is formed by the shrinkage, the temperature of the foamed material is already lowered, and the foam cannot be sufficiently foamed even at this stage.

The present invention has been made devised in view of the above circumstances, a first step of performing vulcanization by close contact with the bladder to the green tire by supplying high pressure fluid to the blanking ladder, the first After the step, the foaming material is efficiently obtained on the basis of including a second step of accelerating the foaming of the foamed material by immediately separating the bladder from the inner surface of the tread by vacuuming the bladder. And it aims at providing the manufacturing method of the pneumatic tire which can be fully foamed.

  Invention of Claim 1 among this invention is a manufacturing method of the pneumatic tire which manufactures the pneumatic tire in which the sound absorption tool which consists of a foam and was extended in the tire circumferential direction was provided in the lumen | bore surface side of the tread part. A raw tire molding step in which a foam material containing a foaming agent is disposed on the inner cavity surface side to mold a raw tire; and a vulcanization step in which the raw tire is vulcanized using a mold and a bladder; The vulcanizing step includes a first stage of vulcanization by supplying a high-pressure fluid to the inside of the bladder to bring the bladder into close contact with the inner surface of the tread portion, and the first stage. After the step, the second step of evacuating the bladder to immediately separate the bladder from the inner surface of the tread portion to promote foaming of the foamed material is included.

  The invention according to claim 2 is the method for producing a pneumatic tire according to claim 1, wherein the second stage is performed without opening a mold.

In the present invention , a high pressure fluid is supplied to the bladder, the bladder is brought into close contact with the green tire and vulcanized, and after this first stage, the bladder is evacuated to obtain the tread portion. A second step of immediately separating the bladder from the tire inner surface to promote foaming of the foamed material. For this reason, in the second stage, since the volume expansion space for foaming the foam material is quickly provided, the foam material can be efficiently foamed. In particular, as in the second aspect, by contracting the bladder while the mold is closed, heat dissipation inside the mold can be prevented, and the foamed material can be foamed more effectively.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, sectional drawing of the pneumatic tire 1 obtained by the manufacturing method of the pneumatic tire of this embodiment is shown. The pneumatic tire 1 includes a tread portion 2, a pair of sidewall portions 3 and 3 extending inward in the tire radial direction from both sides thereof, and an inner end of the sidewall portion 3 and is attached to a rim J. The sound absorbing device 10 is formed of a foam provided on the tire lumen surface 9 side.

  The pneumatic tire 1 includes a carcass 6 composed of a carcass ply 6A wound around the bead core 5 of the bead portion 4 from the tread portion 2 through the sidewall portion 3 in accordance with the conventional practice, and the tread portion 2 on the outer side in the radial direction. A belt layer 7 including at least two belt plies 7A and 7B disposed inside the belt, and a reinforcing member such as a bead apex 8 which is arranged on the bead portion 4 and extends outwardly in the tire radial direction from the bead core 5. It is out.

  In the present embodiment, the sound absorbing tool 10 is fixed to the lumen surface 9 a of the tread portion of the tire lumen surface 9 formed by the inner liner rubber 11. The sound absorber 10 is, for example, a horizontally long flat in the tire axial direction, and more specifically extends in the tire circumferential direction with a substantially trapezoidal cross section in which the width in the tire axial direction decreases smoothly inward in the tire radial direction. Such a sound absorber 10 may be an annular body that is continuous in the tire circumferential direction, or may be partially interrupted. However, in order to prevent weight imbalance, the sound absorber 10 desirably has a cross-sectional shape that is substantially symmetrical with respect to the tire equator C.

  The sound absorbing tool 10 is desirably formed from a foam having closed cells and / or open cells, preferably a foam having open cells. The foam is preferably a foamed rubber or elastomer. Details of these will be described later.

  The sound absorbing tool 10 made of foam absorbs vibration energy due to resonance generated in the tire lumen i surrounded by the pneumatic tire 1 and the rim J (converts it into thermal energy), and suppresses cavity resonance during traveling. Therefore, road noise during traveling is reduced. Further, by providing the sound absorbing tool 10 on the inner cavity surface 9a side of the tread portion, the centrifugal force during traveling can press the sound absorbing tool 10 against the inner cavity surface 9a and effectively prevent the separation or the like. Note that the inner surface 9a of the tread portion is an inner surface having a width BW of the belt layer 7 in the tire axial direction.

Next, a method for manufacturing the pneumatic tire 1 according to the present invention will be described. As shown in FIG. 2, first, a process of forming a green tire 30 in which a foam material 10G in which a foaming agent is blended is arranged on the lumen surface 9a side is performed.

  In this step, the toroidal raw tire 30 is formed using a tire molding drum (not shown). The raw tire 30 includes a tread rubber 2G, a side wall rubber 3G, a clinch rubber 4G disposed in contact with the rim J, a carcass ply 6A, a belt layer 7, a bead apex rubber 8G, and the sheet-like foam material 10G. It is pasted sequentially. The rubber part contained in each tire member is in an unvulcanized state. Here, the “unvulcanized state” includes all aspects that have not reached complete vulcanization, and the so-called semi-vulcanized state is included in the “unvulcanized state”.

  In the present embodiment, an unvulcanized foam material 10G is attached to the inner side of the inner liner rubber 11G that forms the tire lumen surface 9. The foam material 10G may be disposed between the inner liner rubber 11G and the carcass ply 6A. The foam material 10G is formed, for example, in a belt shape extending in the tire circumferential direction with a substantially rectangular cross section that is horizontally flat in the tire axial direction. The length of the foamed material 10G in the tire circumferential direction is set according to the target sound absorber 10. Therefore, it may be an annular body that is continuous in the tire circumferential direction or may have a discontinuous portion.

  As the foam material 10G, various materials can be used without particular limitation as long as the foam material 10G undergoes volume expansion by being foamed by heat during vulcanization of the raw tire 30. As such a foaming material, a composition obtained by blending a polymer such as rubber, resin, or elastomer with a foaming agent that causes foaming in addition to various additives and reinforcing materials is preferably used.

  Examples of the rubber polymer include natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, butyl rubber, halogenated butyl rubber, brominated butyl rubber, and ethylene propylene rubber. It can be used by blending. Particularly preferably, in consideration of adhesiveness to the inner liner rubber 11G, it is desirable to include a butyl rubber of the same type as the inner liner rubber 11G.

  The resin or elastomer is preferably, for example, polyurethane, polyethylene, epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol resin, nylon resin or polycarbonate resin.

  The foaming agent is not particularly limited as long as it can be foamed by heat during vulcanization of the raw tire. For example, azodicarbonamide (ADCA), N, N′-dinitrosopentamethylenetetramine (DPT) or 4,4′-oxybis (benzenesulfonylhydrazide) (OBSH) or the like can be used. The blending amount of the foaming agent can be appropriately adjusted according to the target foaming ratio, but is preferably 2 PHR or more, more preferably 3 PHR or more, and the upper limit is preferably 10 PHR or less. Preferably it is 7 PHR or less. In addition, in order to control the decomposition | disassembly behavior of a foaming agent appropriately, a foaming adjuvant etc. can also be mix | blended. As the foaming aid, for example, a usual sulfenamide accelerator is used, and preferably 0.5 PHR or more and 1.5 PHR or less.

  Next, as shown in FIG. 3, a process of vulcanizing the raw tire 30 using a mold M and a bladder B is performed. The mold M includes, for example, an upper mold MU that can move up and down in the radial direction and can form a tread portion, and left and right side molds ML and MR that can be contacted and separated in the tire axial direction and can form a bead portion from a sidewall portion. including. The raw tire 30 is thrown into the molds MU, ML and MR in an open state. Further, after the mold M is closed, the raw tire 30 is heated and the bladder B is expanded in the tire lumen i by filling with the high-pressure fluid. Thereby, the bladder B closely_contact | adheres to the lumen | bore surface 9a of a tread part. In this way, the first stage of the vulcanization process is performed.

  In the first stage, each rubber is plasticized and vulcanized into a cross-sectional shape formed by the gap between the mold M and the bladder B. On the other hand, since the foam material 10G is strongly pressed by the bladder B and a sufficient space for expansion is not obtained, the foaming is substantially suppressed even when the foaming temperature of the foaming agent is reached.

  Next, in the present embodiment, when the vulcanization of each part is almost finished except for the foaming of the foaming material 10G, the mold M remains closed without being opened as shown in FIG. In this state, the inside of the bladder B is evacuated to forcibly and rapidly contract the bladder B. Thereby, the bladder B is immediately separated from the lumen surface 9a of the tread portion, and provides a space for the foam material 10G to foam in the mold M. Further, since the mold M remains closed, heat dissipation inside the mold can be prevented, and the temperature inside the mold can also be maintained at a temperature suitable for foaming of the foam material 10G. Thereby, the 2nd process of promoting foaming of foaming material 10G is performed.

  Then, after a sufficient time has passed for foaming of the foam material 10G, the upper mold MU is moved outward in the tire radial direction and the left and right side molds ML and MR are separated as shown in FIG. Thereby, the sound absorbing tool 10 can be efficiently formed by sufficiently foaming the foam material 10G.

  In addition, in FIG. 6, the time chart of a vulcanization process is shown. In this chart, the vertical axis represents temperature and the horizontal axis represents time, and the temperature of the foam material 10G and the temperature of the outer surface of the tread rubber 2G are displayed as an example. In the vulcanization step, after the first step is performed at time t1, the bladder B is forcibly contracted, and the second step is performed at time t2 while the mold M is closed. When the second step is finished, the mold M is opened (mold opening). Although the temperature of rubber | gum falls by opening the metal mold | type M, since the 2nd process is performed by closing the metal mold | die M, the temperature of the foaming material 10G can be maintained at high temperature. The time t2 required for the second step can be appropriately determined according to the characteristics and volume of the foam material 10G. The time t2 can be set, for example, at 30 seconds or less, and preferably 2 seconds or more and 20 seconds or less.

Next, a reference example will be described. In this embodiment, as shown in FIG. 7, the pneumatic tire 1 includes a green tire molding step of molding an unvulcanized green tire 30 using a core 12 for green tire molding, and the green tire. And a vulcanization step of vulcanizing 30 together with the core 12.

  The core 12 includes, for example, an inner ring 15 that is coaxial and annular with the tire rotation axis CL, an annular middle ring 16 that is fitted into the inner ring 15, and a tire lumen surface 9 that is fitted into the middle ring 16. It is configured as a so-called assembly core including an annular outer ring 17 having a molding surface 18 that can be molded. The outer ring 17 is composed of a core piece 17A disposed in the center thereof and a pair of left and right divided pieces 17B disposed on both sides so as to cover the core piece 17A. These pieces 17A and 17B are both By connecting the fan-shaped segments divided in the tire circumferential direction, it is configured substantially continuously in the tire circumferential direction.

  After the pneumatic tire 1 is formed on the outer side of the core 12, the inner ring 15 and the middle ring 16 are sequentially removed in the tire axial direction, and the core piece 17A and the divided piece 17B are sequentially removed in the tire. It can be easily disassembled by extracting it radially inward from the cavity.

  The outer ring 17 includes, for example, a pair of a molding surface 18 that can mold the tire lumen surface 9 and a bead-side end portion of the molding surface 18 that protrudes in a flange shape outward in the axial direction. A bead bottom molding surface 19. Further, the molding surface 18 includes a tread molding surface 18a for molding the lumen surface 9a of the tread portion of the raw tire 30, and the tread molding surface 18a is provided with at least one concave groove 20 extending in the tire circumferential direction. It is done.

  The concave groove 20 is preferably formed in accordance with the cross-sectional shape of the sound absorber 10 after vulcanization (that is, the cross-sectional shape of the target sound absorber 10). The concave groove 20 of the present embodiment is formed in a substantially trapezoidal cross section substantially matching the sound absorbing tool 10 shown in FIG. Further, the length of the concave groove 20 in the tire circumferential direction is also set according to the length of the sound absorbing tool 10 in the tire circumferential direction.

  Further, as shown in an enlarged view in FIG. 8, the concave groove 20 is provided with a through hole 21. One end of the through-hole 21 communicates with the concave groove 20 and the inner end in the radial direction preferably communicates with a circumferential groove 22 extending continuously in the circumferential direction provided in the core piece 17A. In addition, the air pressure adjuster P is connected to the circumferential groove 22 via the through hole 25 to the ventilation channel 23 provided in the core piece 17 </ b> A, the through hole 24 provided in the middle ring 16, and the inner ring 15. If necessary, an air seal is appropriately provided.

  Next, in the green tire molding step, as shown in FIG. 8, the clinch bottom rubber 4G1 disposed on the molding surface 18 of the core 12 in contact with the rim J, the inner liner rubber 11G, and the carcass ply 6A are sequentially pasted.

  Also in this embodiment, an unvulcanized foam material 10G is adhered to the inner side of the inner liner rubber 11G that forms the tire lumen surface 9. The foamed material 10G is formed in a belt shape extending in the tire circumferential direction with a substantially rectangular cross-section that is horizontally flat in the tire axial direction, as in the above embodiment.

  The foam material 10G is disposed in the concave groove 20 of the core 12, and has a smaller cross-sectional area than the concave groove 20 (note that the volume of the foam material 10G is also larger than the volume of the concave groove 20). And formed small.) Thus, the foam material 10G is disposed in the concave groove 20 with the gap S on both sides in the tire axial direction and inward in the tire radial direction.

  For the carcass ply 6A, for example, as shown in FIGS. 9A and 9B, a strip-like ply piece 6P having a tire circumferential direction length a smaller than the tire axial direction b is provided on the side. It can be formed by abutting the edges and arranging them on the core 12 in the tire circumferential direction. Such a strip-like ply piece 6P absorbs the difference in the tire circumferential length between the tread part and the bead part by overlapping the ply pieces on the bead part side, and generates a toroid without generating wrinkles or the like. Can be formed with good appearance.

  Further, as shown in FIGS. 10A and 10B, a ply 6S in which a small-length slit e extending from the side edge to the tire axial direction inside is provided on both side edges in the tire axial direction b. The toroidal carcass ply 6A can be formed by winding the core 12 at least once. Also in this embodiment, by overlapping the ply portions separated by the slit e on the bead portion side, the toroidal carcass ply 6A can be formed with good appearance without generating wrinkles or the like.

  After that, as shown in FIG. 11, the annular bead core 5 is fitted into the carcass ply 6 </ b> A, and the bead apex rubber 8 </ b> G is attached to wind up the carcass ply 6 </ b> A around the bead core 5. Thereafter, the clinch side rubber 4G2, the side wall rubber 3G, the belt layer 7, and the tread rubber 2G are attached to the outside thereof. As a result, the raw tire 30 is formed outside the core 12.

  Next, a vulcanization process is performed. FIG. 12 shows a cross-sectional view during the vulcanization process. For example, a split mold similar to that of the above-described embodiment can be adopted as the vulcanizing mold M, and a hollow portion into which the raw tire 30 and the core 12 can be inserted is provided. In the vulcanization step, after both the green tire 30 and the core 12 are put into the vulcanization mold M, the vulcanization mold M is closed and heated. Thereby, each rubber part of the green tire 30 is plasticized and vulcanized and molded along the molding surface 32 of the vulcanization mold M and the molding surface 18 of the core 12. For this reason, it is desirable that the core 12 be formed of a metal material such as an aluminum alloy so as to withstand the heat during vulcanization. Needless to say, the core 12 may be heated in order to positively heat the raw tire 30 from the tire lumen surface 9 side.

  Further, in the vulcanization process, heat from the vulcanization mold M is transmitted to the foam material 10G via the tread rubber 2G and the like, and vacuum is drawn by the air pressure adjuster P, so that the inside of the concave groove 20 is set to a negative pressure. This includes a step of promoting foaming of the foam material 10G. Thus, by setting the inside of the concave groove 20 to a negative pressure, when the foam material reaches a predetermined foaming temperature, the volume can be expanded in the concave groove 20 without causing resistance, and foaming can be promoted.

  Further, the foam material 10G is volume-expanded so as to fill the gap S in the concave groove 20, and the expansion deformation is suppressed by the surface of the concave groove 20, so that the foam material 10G is formed almost equal to the cross-sectional shape of the concave groove 20. Can do. In order to effectively exert such an action, the foam material 10G can be expanded and deformed exceeding the volume Vg of the recessed groove 20, that is, blended with a foaming agent or the like so as to be able to perform expansion deformation that fills the recessed groove 20 during foaming. The amount is preferably set. At the same time, the foam material 10G and the inner liner rubber 11G are vulcanized and bonded together.

  Here, when the inside of the concave groove 20 is set to a negative pressure, the pressure is not particularly limited. However, if the negative pressure is too large (if the gauge pressure is too small), the foamed material 10G becomes the inner during vulcanization. There is a risk of peeling from the liner rubber 11G or distorting the shape of the tread portion. Conversely, if the negative pressure is too small (the gauge pressure is too large), the effect of promoting foaming of the foam material 10G cannot be expected sufficiently. . From such a viewpoint, the preferable negative pressure in the concave groove 20 is a gauge pressure and is desirably about −80 to −20 kPa, more preferably about −80 to −50 kPa.

  In addition, the pressure in the concave groove 20 is largely outside (for example, from the initial vulcanization to 80% of the total vulcanization time) during vulcanization (external communication (atmospheric pressure)) or in a pressurized state (for example, greater than atmospheric pressure). While the inner liner rubber 11G and the tread rubber are firmly vulcanized at 2500 kPa or less), it is particularly desirable to expand the foam material 10G at a stretch using the negative pressure in the groove 20 only at the end of vulcanization.

  When the vulcanization process is completed, the pneumatic tire 1 is taken out from the vulcanization mold M together with the core 12, and then the core 12 is disassembled to obtain the vulcanized pneumatic tire 1.

Further, in the present invention , as shown in FIG. 13, after the vulcanization process, the outer surface 10S facing the tire lumen i of the sound absorber 10 is thinly removed, so that the bubbles p formed therein are formed on the surface. It is desirable to include an exposed surface grinding step. Thereby, the contact opportunity of the bubble p of the sound-absorbing tool 10 and the air in the tire lumen i increases, and the sound-absorbing effect is further improved. In particular, in the embodiment in which the foam material 10G is disposed inside the inner liner rubber 11G and the carcass ply 6A, by performing such a grinding process, the inner liner rubber 11G is peeled off and the foam material 10G is disposed in the tire. It is desirable to expose the cavity i.

  Further, as shown in FIG. 14, the step of pressing and rolling the roller R having a large number of needle-like protrusions 35 on the outer peripheral surface against the surface of the sound absorber 10 before vulcanization or before vulcanization can be preferably performed. . By performing such a process, the protrusion 35 forms a through-hole that allows the closed cells formed inside the sound absorbing tool 10 to communicate with each other, converts them into open cells, and consequently the bubble p and the tire lumen i. It is preferable at the point which can increase the contact opportunity with air.

( Invention )
Ten pneumatic tires for passenger cars having a tire size of 195 / 65R15 were produced according to the present invention (Examples 1 and 2). The specifications of the foamed material before vulcanization are as follows.

<Specifications of foam material>
Width of foam material: 50mm
Foam thickness: 10mm
Formulation of foam material: as shown in Table 1 (The foam material was continuously wound in the circumferential direction.)
<Process time>
First process time t1: 9 minutes Second process time t2: 0.5 minutes

  For comparison, the same raw tires as in the example were used in the conventional method (only the first step, and the bladder was contracted by natural exhaust at the same time when the mold was opened). Manufactured (comparative example).

  When the sound absorbing tool was observed with the naked eye, the foamed material was sufficiently foamed in the example, but the foamed material was hardly foamed in the comparative example.

Next, each pneumatic tire is mounted on the rim, all wheels of a 2000cc domestic FF passenger car are mounted, and the driver's seat side when driving on a road noise measurement path (asphalt rough road) at a speed of 60km / h The vehicle interior sound at the ear position was measured. Then, the sound pressure level of the peak value of the air column resonance sound near the narrow band 240 Hz was measured. The results were evaluated by an index with the sound pressure level of a pneumatic tire (conventional example) without a sound absorbing tool as 100. The larger the value, the better.
Table 2 shows the test results.

  As a result of the test, it was confirmed that the tire of the example reduced road noise. Moreover, it has confirmed that Example 2 which scraped the surface of the sound-absorbing tool among the examples and exposed the bubble exhibited a road noise reduction effect superior to that of Example 1.

( Reference example )
Ten pneumatic tires for passenger cars having a tire size of 195 / 65R15 were produced according to Reference Examples ( Reference Examples 1 and 2 ). The specifications of the foamed material and the like before vulcanization are the same as the embodiment of the present invention . Moreover, the specifications of the concave groove and the like are as follows.

<Specifications of recessed grooves>
Maximum groove width of concave groove: 70mm
Maximum depth of concave groove: 20mm
Groove volume: 266093mm ³
Pressure in the groove: 2000 kPa (gauge), final vulcanization: -70 kPa (gauge)

  When the sound absorbing tool was observed with the naked eye, the foamed material was sufficiently foamed in the example, but the foamed material was hardly foamed in the comparative example.

Next, each pneumatic tire was mounted on a rim, a road noise test similar to the above was performed, and an evaluation was performed using an index with a sound pressure level of a pneumatic tire without a sound absorbing tool (conventional example) as 100. The larger the value, the better.
Table 3 shows the test results.

It is sectional drawing of the pneumatic tire manufactured by this invention. It is sectional drawing of a green tire. It is sectional drawing which shows the 1st step of a vulcanization process. It is sectional drawing which shows the 2nd step of a vulcanization process. It is sectional drawing at the time of removing a tire from a metal mold | die. It is a time chart of a vulcanization process. It is sectional drawing of the core for green tire shaping | molding. FIG. (A) is a development perspective view of a ply piece for manufacturing a carcass ply, and (B) is a perspective view showing a method for attaching the ply piece. (A) is a development perspective view of a carcass ply for manufacturing a carcass ply, and (B) is a perspective view showing a method for attaching the carcass ply. It is sectional drawing explaining a green tire shaping | molding process. It is sectional drawing explaining a vulcanization | cure process. It is an expanded sectional view of a sound absorber. It is sectional drawing explaining the process of making the closed cell of a sound-absorbing tool into an open cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 9 Tire inner cavity surface 9a Inner cavity surface 10 of tread part Sound absorbing tool 10G Foam material 12 Core 20 Groove 30 Raw tire M Mold B Bladder

Claims (2)

A pneumatic tire manufacturing method for manufacturing a pneumatic tire provided with a sound absorbing tool made of foam and extending in the tire circumferential direction on the inner surface of the tread portion,
A raw tire molding step in which a foam material blended with a foaming agent is disposed on the inner cavity surface side to mold a raw tire,
A vulcanization step of vulcanizing the green tire using a mold and a bladder,
The vulcanization step is a first stage in which vulcanization is performed by supplying a high-pressure fluid to the inside of the bladder so that the bladder is brought into close contact with the inner surface of the tread portion;
After the first step, the second step of evacuating the bladder to immediately separate the bladder from the inner surface of the tread portion to promote foaming of the foam material. A method for manufacturing a tire.   The method for manufacturing a pneumatic tire according to claim 1, wherein the second stage is performed without opening a mold.

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