JP7030500B2 - How to manufacture tire molding dies and pneumatic tires - Google Patents

Description

In the present invention, a pair of bead portions, a sidewall portion extending outward in the tire radial direction from each of the bead portions, and a tread portion connected to each tire radial outer end of the sidewall portion to form a tread surface are provided. The present invention relates to a tire molding die for heating and vulcanizing a prepared unvulcanized raw tire.

When manufacturing pneumatic tires, which are rubber products, the vulcanization process is the most time-consuming process, and efforts are still being made to shorten the vulcanization process time. On the other hand, if the vulcanization of the rubber part is insufficient in the vulcanization process, the air generated by the vulcanization reaction of the rubber remains in the vulcanized rubber, and such residual air causes tire failure at the product stage. May be. Therefore, in a normal tire production site, considering that the temperature of raw unvulcanized tires, which are raw materials, the temperature inside the mold, the atmospheric temperature, etc., vary due to seasonal factors, etc., all variations in the vulcanization process are taken into consideration. The time required for the vulcanization process is set by adding the extra time in consideration of.

However, setting the margin time is not preferable from the viewpoint of improving the productivity of the tire, and it has been desired to determine the end time of vulcanization for each tire and efficiently execute the vulcanization process.

In Patent Document 1 below, the impedance of the vulcanized sample is measured while the vulcanization process is in progress, and the optimum vulcanization is when the rate of increase in the polymer resistance value Rp of the vulcanized sample suddenly slows down. A method for adjusting the real-time vulcanization of the vulcanized sample as the stop time is described. However, in this method, it is necessary to measure the impedance of the vulcanized sample by sandwiching the vulcanized sample between two electrodes, and since the tire is usually a laminate of composite materials, this method is used. It is difficult to apply to tires during tire vulcanization.

Japanese Unexamined Patent Publication No. 2003-21149

The present invention has been made in view of the above circumstances, and an object thereof is to be able to accurately measure the temperature of a pneumatic tire during vulcanization in order to surely determine the end time point of the vulcanization process for each tire. The purpose is to provide a mold for tire molding.

The above object can be achieved by the present invention as described below. That is, the present invention includes a pair of bead portions, a sidewall portion extending outward in the tire radial direction from each of the bead portions, and a tread portion connected to each tire radial outer end of the sidewall portion to form a tread surface. A tire molding die for heat-sulfurizing an unsulfurized raw tire provided with at least a tread mold portion that can be pressure-welded to the tread portion, and the tread mold portion is divided in the circumferential direction. It has a plurality of segments that can move in the radial direction of the raw tire, and at least two or more of the segments have a fixing means for fixing the temperature measuring probe and the fixing means toward the inner peripheral surface side. The tire is fixed by the radial temperature measuring probe insertion hole and the fixing means, and extends in the tire radial direction in the temperature measuring probe insertion hole toward the inner peripheral surface side, and the inner peripheral surface side end is the temperature measurement. It is equipped with a temperature measuring probe mounted in a posture that can be embedded in the shoulder portion of the tread portion beyond the inner peripheral surface side end of the probe insertion hole.
The tire molding die is characterized in that the outer diameter D1 of the temperature measuring probe is formed smaller than the inner diameter D2 of the temperature measuring probe insertion hole.

The tire molding die according to the present invention is a so-called "segmental mold" in which at least the tread mold portion is divided in the circumferential direction, and the above-mentioned specific is divided into at least two or more segments among the divided segments. Equipped with a temperature measuring probe. This makes it possible to accurately measure the temperature of the pneumatic tire during vulcanization, particularly the temperature of the shoulder portion of the tread portion where vulcanization of the tire is most difficult to proceed. In addition, since the temperature measurement probes are arranged in two or more segments, accurate temperature measurement is possible because the temperature is measured at multiple locations, and even if a certain temperature measurement probe is damaged, even if a certain temperature measurement probe is damaged. Measurement with other temperature measurement probes is possible.

Further, in the tire molding die according to the present invention, both the traveling direction of the segment and the disposing direction of the temperature measuring probe are the radial directions of the raw tire. As described above, since the segment moves in the radial direction of the raw tire, if the arrangement direction of the temperature measuring probe is also the radial direction of the raw tire, the load is minimized when the temperature measuring probe is embedded in the shoulder portion. preferable. Considering the reduction of the load on the temperature measuring probe, the deviation between the traveling direction when the segment moves in the radial direction and the radial arrangement direction of the temperature measuring probe is preferably 3 ° or less. It is more preferably 1 ° or less.

In the tire molding die, the outer diameter D1 of the temperature measuring probe is preferably 1 to 10 mm.

In the tire molding die, when the length of the temperature measuring probe measured from the inner peripheral surface side end of the fixing means is L1, it is preferable that L1 / D1 is 10 or more.

In the tire molding die, it is preferable that the gap between the inner peripheral surface side end of the temperature measuring probe insertion hole and the temperature measuring probe is closed by a spacer having a thermal conductivity smaller than that of the segment.

In the tire molding die, it is preferable that the gap between the temperature measuring probe insertion hole and the temperature measuring probe is closed by a heat insulating material having a thermal conductivity smaller than that of the segment.

In the tire molding die, it is preferable that the temperature measuring probe is a platinum resistance temperature detector.

Further, the present invention is a method for manufacturing a pneumatic tire including a vulcanization step of heating and vulcanizing in the tire molding mold according to any one of the above, wherein the vulcanization step includes a pair of bead portions and the above. A tread portion of an unvulcanized raw tire provided with a sidewall portion extending outward in the tire radial direction from each of the bead portions and a tread portion connecting to the tire radial outer end of each of the sidewall portions to form a tread. The present invention relates to a method for manufacturing a pneumatic tire, which comprises a step of measuring the temperature of the shoulder portion by embedding a temperature measuring probe in the shoulder portion included in the above.

According to the above manufacturing method, the temperature of the pneumatic tire during vulcanization, particularly the temperature of the shoulder portion of the tread portion where vulcanization of the tire is most difficult to proceed can be accurately measured, so that vulcanization is performed for each tire. The end point of the process can be reliably determined.

In the method for manufacturing a pneumatic tire, the vulcanization step obtains time-series data of the temperature of the raw tire being vulcanized by the first step of embedding a temperature measuring probe in the shoulder portion and the temperature measuring probe. It is provided with a second step of acquiring at intervals of seconds or less and a third step of ending the vulcanization step when heat absorption due to the vulcanization reaction is detected in the vicinity of the target vulcanization temperature based on the time series data. Is preferable.

In the above manufacturing method, first, a pair of bead portions, a sidewall portion extending outward in the tire radial direction from each of the bead portions, and a tread portion connecting to each tire radial outer end of the sidewall portion to form a tread surface. A temperature measurement probe is embedded in the tread portion corresponding to the slowest vulcanization portion of the unvulcanized raw tire provided with the above (first stage), and the temperature series of the raw tire being vulcanized by the temperature measurement probe is used. Data is acquired at intervals of 10 seconds or less (second stage). Then, based on the time-series data, the vulcanization step is terminated when the endothermic reaction due to the vulcanization reaction is detected in the vicinity of the target vulcanization temperature (third stage). This makes it possible to easily identify the vulcanization end point in the vulcanization process of the pneumatic tire. As a result, it is not necessary to set an extra spare time, and the productivity of the pneumatic tire can be increased. In addition, since it can be confirmed that the vulcanization reaction is surely completed for each pneumatic tire, a quality assurance system can be established. The term "near the target vulcanization temperature" preferably means a range of ± 10 ° C. of the set target vulcanization temperature.

In the method for manufacturing a pneumatic tire, the third step further plots a vulcanization temperature curve showing the relationship between the temperature of the raw tire and the vulcanization time based on the time series data. It is preferable to include a third b step in which the vulcanization step is terminated when a downwardly convex inflection that appears in the vicinity of the target vulcanization temperature is detected in the vulcanization temperature curve. According to this configuration, since the downwardly convex inflection point that appears near the target vulcanization temperature in the plotted vulcanization temperature curve is set as the vulcanization end point, it is easy and convenient to identify. This makes it possible to more reliably determine the vulcanization end point of the pneumatic tire, and further increase the productivity of the pneumatic tire.

In the method for manufacturing a pneumatic tire, the target vulcanization temperature is preferably 125 to 165 ° C. If the target vulcanization temperature is set high, the vulcanization rate of pneumatic tires will be high, so the detection of the vulcanization end point based on the time when heat absorption due to the vulcanization reaction is detected, and the target vulcanization with the plotted vulcanization temperature curve. It may be difficult to detect the vulcanization end point based on the downwardly convex turning point that appears near the sulfurization temperature. On the other hand, when the target vulcanization temperature is 125 to 165 ° C., particularly 125 to 145 ° C., it is easy to identify the vulcanization end point, so that the productivity of the pneumatic tire can be further improved. When the target vulcanization temperature is 125 to 145 ° C, it may be called low temperature vulcanization of the pneumatic tire, but in the case of low temperature vulcanization, the vulcanization speed of the pneumatic tire becomes slow, so there is a margin in the past. It was necessary to secure more time than usual. Therefore, the merit of low-temperature vulcanization, which is to suppress thermal deterioration of pneumatic tires under high temperature during vulcanization, may be impaired by an increase in vulcanization time. However, in the present invention, even in low temperature vulcanization (target vulcanization temperature is 125 to 145 ° C.), the margin time can be designed to be shorter than usual, so that deterioration of the physical properties of the pneumatic tire due to thermal deterioration can be prevented. Can be done.

A tire meridian sectional view showing an example of a tire that can be manufactured in the present invention. Cross-sectional view conceptually showing the tire molding die of the present invention. A cross-sectional view conceptually showing a state in which a temperature measuring probe is embedded in a shoulder portion in a segment constituting the tread mold portion of the mold of the present invention. An example of a graph showing a vulcanization temperature curve in one embodiment of the present invention.

An embodiment of the present invention will be described with reference to the drawings. The raw tire 9 shown in FIG. 1 is continuous with a pair of bead portions 1, a sidewall portion 2 extending outward in the tire radial direction from each of the bead portions 1, and each tire radial outer end of the sidewall portion 2. It is a pneumatic tire provided with a tread portion 3 constituting a tread surface. An annular bead core 1a is arranged in the bead portion 1.

The carcass layer 4 reaches the bead portion 1 from the tread portion 3 via the sidewall portion 2, and its end portion is folded back via the bead core 1a. The carcass layer 4 is composed of at least one carcass ply. The carcass ply is formed by covering a carcass cord extending at an angle of approximately 90 ° with respect to the tire circumferential direction with a topping rubber.

The belt layer 5 is attached to the outside of the carcass layer 4 at the tread portion 3, and is covered from the outside by the tread rubber 6. The belt layer 5 is composed of a plurality of belt plies (two in the present embodiment). Each belt ply is formed by covering a belt cord extending inclined with respect to the tire circumferential direction with a topping rubber, and the belt cords are laminated so as to intersect each other in opposite directions between the plies.

The tread rubber 6 may be configured with only one layer, or may be configured with a so-called cap base structure having a base tread on the inner side in the tire radial direction and a cap tread located on the outer peripheral side thereof.

The raw tire 9 shown in FIG. 1 is a raw tire in an unvulcanized state, and is shaped into the shape of a product tire in the vulcanization process described later (see FIG. 2), and various treads are formed on the tread surface thereof. A pattern is formed.

In the vulcanization molding of the raw tire 9, the tire molding die (hereinafter, also simply referred to as “mold”) according to the present invention is used. FIG. 2 shows a cross-sectional view conceptually showing the tire molding die of the present invention. The raw tire 9 is set in the mold 10 in an unvulcanized state, and the vulcanization step is performed by applying heat and pressure to the raw tire 9 in the mold 10.

The mold 10 includes at least a tread mold portion 11 that can be pressed against the tread portion 3 of the raw tire 9. In the present embodiment, the mold 10 includes a tread mold portion 11 in contact with the tread surface of the raw tire 9, a lower mold portion 12 in contact with the outer surface of the tire facing downward, and an upper mold portion 13 in contact with the outer surface of the tire facing upward. To prepare for. These are configured to be freely displaceable between the mold-fastened state and the mold open state by an opening / closing mechanism (not shown) installed around them, and the structure of such an opening / closing mechanism is well known. The tread mold portion 11 is further divided into a plurality of segments in the circumferential direction, and is movable in the radial direction of the raw tire 9 arranged in the mold 10. Further, the mold 10 is provided with a platen plate (not shown) having a heat source such as an electric heater or a steam jacket, whereby each mold portion is heated.

A central mechanism 14 is provided coaxially with the tire in the central portion of the mold 10, and a tread mold portion 11, a lower mold portion 12, and an upper mold portion 13 are installed around the central mechanism 14. The central mechanism 14 has a rubber bag-shaped bladder 15 and a center post 16 extending in the tire axial direction. The center post 16 is provided with an upper clamp 17 and a lower clamp 18 for gripping the end portion of the bladder 15. ing.

In the central mechanism 14, a medium supply path 21 for supplying the heating medium into the bladder 15 is extended vertically, and an ejection port 22 is formed at the upper end of the medium supply path 21. A heating medium supplied from the heating medium supply source 23 and a supply pipe 24 through which the pressure medium supplied from the pressure medium supply source 26 flows are connected to the medium supply path 21. The heating medium is supplied according to the opening / closing operation of the valve 25, and the pressurizing medium is supplied according to the opening / closing operation of the valve 28.

Further, in the central mechanism 14, a medium discharge passage 31 for discharging a high-temperature high-pressure fluid in which a heating medium and a pressurized medium in the bladder 15 are mixed is extended up and down, and is provided at the upper end of the medium discharge passage 31. The collection port 32 is formed. A discharge pipe 34 through which a high-temperature high-pressure fluid flows is connected to the medium discharge passage 31, and a blow valve 33 for operating the opening / closing of the discharge pipe 34 is provided in the discharge pipe 34. The pump 35 may use a method of forcibly circulating the high-temperature high-pressure fluid so that the high-temperature high-pressure fluid passing through the medium discharge path 31 is re-supplied to the inside of the bladder 15 via the medium supply path 21.

Hereinafter, the segment 41 constituting the tread mold portion 11 included in the mold 10 of the present invention will be described. FIG. 3 shows a cross-sectional view conceptually showing a state in which a temperature measuring probe is embedded in a shoulder portion in a segment constituting the tread mold portion of the mold of the present invention. In FIG. 3, the “inner peripheral surface side” means the side close to the raw tire 9 when the raw tire 9 is set in the mold 10. The segment 41 is one in which the tread mold portion 11 is divided into, for example, 6 to 12 in the circumferential direction, and each of them moves in the radial direction of the raw tire 9 to press-contact the tread portion 3 of the raw tire 9. It is possible. It is more preferable that the number of divisions of the segment 41 is an odd number in the range of 6 to 12.

At least one of the segments 41 is fixed by the fixing means 42 for fixing the temperature measuring probe 44, the temperature measuring probe insertion hole 43 extending radially from the fixing means 42 toward the inner peripheral surface side, and the fixing means 42. , The inside of the temperature measuring probe insertion hole 43 extends in the tire radial direction toward the inner peripheral surface side, and the inner peripheral surface side end exceeds the inner peripheral surface side end of the temperature measuring probe insertion hole 43 and the shoulder portion of the tread portion 3. It is provided with a temperature measuring probe 44 mounted in a posture that can be embedded in the 3S. The temperature measuring probe 44 may be attached to one of a plurality of segments 41, may be attached to a plurality of segments 41, or may be attached to all the segments 41.

The fixing means 42 for fixing the temperature measuring probe 44 has, for example, a double nut on the outer peripheral surface side and a screw structure on the inner peripheral surface side, so that the temperature measuring probe 44 protrudes from the temperature measuring probe hole 43. It can be designed so that the height L2 can be adjusted.

A temperature measuring probe insertion hole 43 extending in the radial direction is formed on the inner peripheral surface side of the fixing means 42. The inner peripheral surface side of the temperature measuring probe insertion hole 43 is open, and the temperature measuring probe 44 is designed so as to protrude into the cavity of the mold 10 and be embedded in the shoulder portion 3S of the tread portion 3. ..

The end of the temperature measuring probe 44 on the outer peripheral surface side is fixed by the fixing means 42, extends toward the inner peripheral surface side in the temperature measuring probe insertion hole 43 in the tire radial direction, and the temperature measuring on the inner peripheral surface side end. It is attached in a posture that can be embedded in the shoulder portion 3S of the tread portion 3 beyond the inner peripheral surface side end of the probe insertion hole 43. The cross-sectional shape of the temperature measuring probe 44 is not particularly limited, but is preferably circular.

As described above, since the segment 41 moves in the radial direction of the raw tire 9, when the arrangement direction of the temperature measuring probe 44 is also the radial direction of the raw tire 9, when the temperature measuring probe 44 is embedded in the shoulder portion 3S. , It is preferable because the load is the smallest.

In the present invention, as a temperature measuring probe used when measuring the brewing temperature, a resistance temperature measuring resistor utilizing the property that the electric resistance of a metal changes with respect to a temperature change can be used. Examples of such metals include platinum, nickel, and copper, but in the present invention, the resistance value change (sensitivity) to a temperature change is large, and as a result, the platinum temperature measurement is extremely sensitive to a temperature change. Resistors can be used particularly preferably.

The temperature measuring probe 44 is arranged in the temperature measuring probe insertion hole 43, and the outer diameter D1 of the temperature measuring probe 44 is formed to be smaller than the inner diameter D2 of the temperature measuring probe insertion hole 43 (FIG. 3B). .. According to this configuration, when the segment 41 is heated during vulcanization, rubber penetrates into the gap between the temperature measuring probe 44 and the temperature measuring probe insertion hole 43 during vulcanization, and the temperature measuring probe 44 and the segment 41 are directly connected to each other. It is possible to prevent contact. As a result, the temperature of the tread portion 3 corresponding to the slowest vulcanization portion can be accurately measured by the temperature measuring probe 44. The outer diameter D1 of the temperature measuring probe 44 can be appropriately designed according to the size of the pneumatic tire to be manufactured, but is preferably 1 to 10 mm. Further, the inner diameter D2 of the temperature measuring probe insertion hole 43 can be appropriately designed according to the size of the pneumatic tire to be manufactured, but it may be 0.5 to 1.0 mm larger than the outer diameter D1 of the temperature measuring probe 44. preferable.

When the length of the temperature measuring probe 44 measured from the inner peripheral surface side end of the fixing means 42 is L1, if L1 / D1 is 10 or more, the measurement error due to heat conduction from the segment 41 to the temperature measuring probe 44. Is preferable because it can reduce the amount of heat. The protrusion height L2 of L1 and the temperature measuring probe 44 from the temperature measuring probe hole 43 can be appropriately designed according to the size of the pneumatic tire to be manufactured. Of these, L2 is preferably 0.5 to 10 mm. Further, the depth L3 of the temperature measuring probe hole from the inner peripheral side end of the fixing means 42 can also be appropriately designed according to the size of the pneumatic tire to be manufactured.

FIG. 3B shows an example in which the gap between the temperature measuring probe insertion hole 43 and the temperature measuring probe 44 is not closed, but as shown in FIG. 3C, the inside of the temperature measuring probe insertion hole 43 is shown. The gap between the peripheral end and the temperature measuring probe 44 may be closed by the spacer 45 having a thermal conductivity smaller than that of the segment 41. According to this configuration, rubber does not penetrate into the gap between the temperature measuring probe 44 and the temperature measuring probe insertion hole 43 during vulcanization, and the circumference of the temperature measuring probe 44 becomes hollow. Even in this configuration, the temperature of the tread portion 3 corresponding to the slowest vulcanization portion can be accurately measured by the temperature measuring probe 44. The length L4 of the spacer 45 is preferably 10 to 50 mm in the depth direction of the segment 41, for example. The spacer 45 can be made of a material having a thermal conductivity smaller than that of the segment 41, for example, a metal such as constantan, titanium, or nichrome.

Further, as shown in FIG. 3D, the gap between the temperature measuring probe insertion hole 43 and the temperature measuring probe 44 may be closed by the heat insulating material 46 having a thermal conductivity smaller than that of the segment. According to such a configuration, since the temperature measuring probe 44 is covered with the heat insulating material 46 at the time of vulcanization, the temperature of the tread portion 3 corresponding to the slowest vulcanization portion can be accurately measured by the temperature measuring probe 44. The length of the heat insulating material 46 is preferably, for example, 50 to 80% of the depth L3 of the temperature measuring probe hole. Like the spacer 45, the heat insulating material 46 can also be made of a metal such as constantan, titanium, or nichrome.

Next, the vulcanization step in the method for manufacturing a pneumatic tire of the present invention will be specifically described.

First, the raw tire 9 is set in the mold 10 as shown in FIG. 2, and the raw tire 9 is shaped to be close to the inner surface shape of the mold 10 by the expanded bladder 15. As a result, the raw tire 9 is held by the bladder 15 and addressed to each of the tread mold portion 11, the lower mold portion 12, and the upper mold portion 13. At this point, a temperature measuring probe is embedded in the slowest part of the vulcanization of the raw tire 9 (first stage). The slowest vulcanization portion means a portion where vulcanization of the tire is most difficult to proceed, and usually means a shoulder portion of the tread portion 3. In particular, among the shoulder portions, the position where the thickness of the tread portion 3 is maximized, which is measured along the normal of the inner surface of the tread portion 3 after vulcanization, is preferably the slowest vulcanization portion. In any case, in the present invention, in order to measure the vulcanization temperature in the slowest vulcanization portion, the temperature measuring probe is embedded in the slowest vulcanization portion of the raw tire 9. As an embedding method, for example, when a temperature measuring probe is arranged at a position corresponding to the shoulder portion of the tread mold portion 11 and the tread mold portion 11 moves in the radial direction of the raw tire 9 and the raw tire 9 is addressed. It is conceivable to design the temperature measuring probe so as to be embedded while being pushed into the raw tire 9. With the temperature measuring probe embedded in the raw tire 9 in this way, the temperature of the raw tire is measured at the time of the vulcanization process, and at the end of the vulcanization process, when the tire is removed from the mold 10 including the tread mold portion 11. The temperature measuring probe may be extracted from the slowest part of the vulcanization at the same time.

Subsequently, outside heating is performed by heating the mold 10 to heat the tire 9 from the tire outer surface side, and inside heating is performed by supplying a high-temperature heating medium to the bladder 15 in the mold 10 to heat the tire 9 from the tire inner surface side. The raw tire 9 is vulcanized by heating the tire. The mold 10 is preheated by the steam jacket or the like described above, whereby the outside heating is performed. The inner heating is performed by supplying the heating medium into the bladder 15 through the medium supply path 21 after shaping the tire 9. After supplying the heating medium for a predetermined time, the pressurizing medium is subsequently supplied into the bladder 15 to pressurize the tire 9 at a high pressure. As the heating medium, for example, steam or high-temperature water is used, and as the pressure medium, for example, an inert gas such as nitrogen gas or steam is used.

The temperature measurement probe acquires time-series data of the temperature of the raw tire being vulcanized at intervals of 10 seconds or less (second stage). For the acquisition of such time-series data, a high-precision digital data logger generally distributed in the market (temperature resolution of about 0.001 ° C, accuracy of about ± 0.005 ° C, minimum temperature value acquisition interval of 1 second) can be used. .. In the second stage, when the data acquisition interval of the time-series data of the temperature of the raw tire during vulcanization is short, it is preferable because the final vulcanization end point can be determined more accurately. Specifically, the time-series data of the temperature of the raw tire during vulcanization is preferably acquired at intervals of 5 seconds or less, and preferably at intervals of 1 second or less. On the other hand, if the data acquisition interval of the time-series data of the temperature of the raw tire during vulcanization is too short, the noise may become large and it may be difficult to accurately determine the vulcanization end point. Therefore, the data acquisition interval of the time-series data of the temperature of the raw tire during vulcanization is preferably 0.5 seconds or more.

After the second step, the vulcanization step is terminated when the endothermic reaction due to the vulcanization reaction is detected in the vicinity of the target vulcanization temperature based on the time series data (third step). This makes it possible to easily identify the vulcanization end point in the vulcanization process of the pneumatic tire. The target vulcanization temperature is preferably 125 ° C. to 165 ° C., more preferably 125 ° C. to 145 ° C., and particularly preferably 125 to 135 ° C., because it is easy to identify the vulcanization end point. .. As a method of detecting heat absorption by the vulcanization reaction, the temperature change amount of the raw tire in a predetermined period (for example, 1 second if the data acquisition interval is 1 second) is calculated in the vicinity of the target vulcanization temperature, and the temperature change amount is calculated. It is possible to make a decision based on.

In the present invention, the third step can be divided into two, and the vulcanization end point can be determined more easily. First, based on the time series data, a vulcanization temperature curve showing the relationship between the temperature of the raw tire and the vulcanization time is plotted (stage 3a). FIG. 4 is an example of a graph showing a vulcanization temperature curve according to an embodiment of the present invention, in which A is the temperature (° C.) of a raw tire when the vulcanization start point is the time when the mold 10 is completed. The vulcanization temperature curve with the vertical axis and time (seconds) as the horizontal axis is shown. As shown in FIG. 4, when a pneumatic tire is vulcanized using the tire molding die according to the present invention, even a minute temperature change within 1 ° C. can be accurately measured.

In this embodiment, the vulcanization temperature curve A when the target vulcanization temperature is set to 130 ° C. and the time-series data of the temperature of the raw tire is acquired at 1-second intervals is shown. The vulcanization temperature curve B is an enlargement of the vicinity of the target vulcanization temperature of the vulcanization temperature curve A (2000 seconds before to 8000 seconds before). After the third a step, the vulcanization step is terminated when a downwardly convex inflection point P appearing in the vicinity of the target vulcanization temperature is detected on the plotted vulcanization temperature curve A (third step 3b). In the present embodiment, in the vulcanization temperature curve B, a point P corresponding to a downwardly convex inflection that appears near the target vulcanization temperature (130 ° C.) (although it is described as BPT in the current FIG. 3). , Corrected to point P) is easily detectable, and vulcanization can be completed with the point when this point P is detected as the vulcanization end point.

After the vulcanization step is completed, the temperature measuring probe arranged in the mold 10 is taken out from the vulcanized tire while the mold 10 is in the open state. As a result, it is possible to identify the vulcanization end point for each tire and manufacture a pneumatic tire while shortening the vulcanization time.

The present invention is not limited to the above-described embodiment, and various improvements and changes can be made without departing from the spirit of the present invention.

Claims (7)

A pair of bead portions, a sidewall portion extending outward in the tire radial direction from each of the bead portions, and a tread portion connected to each tire radial outer end of the sidewall portion to form a tread surface. A tire molding die that heats and vulcanizes raw vulcanized tires.
At least a tread mold portion that can be pressure-welded to the tread portion is provided.
The tread mold portion is divided in the circumferential direction and has a plurality of segments that are movable in the radial direction of the raw tire.
Of the segments, at least two or more segments are provided by the fixing means for fixing the temperature measuring probe, the temperature measuring probe insertion hole extending radially from the fixing means toward the inner peripheral surface side, and the fixing means. It is fixed and extends in the tire radial direction in the temperature measuring probe insertion hole toward the inner peripheral surface side, and the inner peripheral surface side end exceeds the inner peripheral surface side end of the temperature measuring probe insertion hole and the shoulder of the tread portion. Equipped with a temperature measuring probe mounted in a position that can be embedded in the part,
A tire molding die characterized in that the inner diameter D2 of the temperature measuring probe insertion hole is formed to be 0.5 to 1.0 mm larger than the outer diameter D1 of the temperature measuring probe . The tire molding die according to claim 1, wherein the outer diameter D1 of the temperature measuring probe is 1 to 10 mm. The tire molding die according to claim 1 or 2, wherein L1 / D1 is 10 or more when the length of the temperature measuring probe measured from the inner peripheral surface side end of the fixing means is L1. The tire according to any one of claims 1 to 3, wherein the gap between the inner peripheral surface side end of the temperature measuring probe insertion hole and the temperature measuring probe is closed by a spacer having a thermal conductivity smaller than that of the segment. Mold for molding. The tire molding die according to any one of claims 1 to 3, wherein the gap between the temperature measuring probe insertion hole and the temperature measuring probe is closed by a heat insulating material having a thermal conductivity smaller than that of the segment. The tire molding die according to any one of claims 1 to 5, wherein the temperature measuring probe is a platinum resistance temperature detector. A method for manufacturing a pneumatic tire, comprising a vulcanization step of heating and vulcanizing in the tire molding die according to any one of claims 1 to 6.
The tread portion in which the vulcanization step is connected to a pair of bead portions, a sidewall portion extending outward in the tire radial direction from each of the bead portions, and a tire radial outer end of each of the sidewall portions to form a tread surface. A method for manufacturing a pneumatic tire, comprising a step of measuring the temperature of the shoulder portion by embedding a temperature measuring probe in the shoulder portion included in the tread portion of the unvulcanized raw tire provided with the above. ..

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