JP6939208B2 - Tire vulcanization method - Google Patents

Description

The present invention relates to a tire vulcanizing method, and more particularly, by controlling the speed of closing the mold in accordance with the contact state of the green tire and the mold in the tire vulcanization, possible to improve the tire quality about the tire vulcanizing method.

Generally, when a tire is vulcanized, the mold is closed from the outside of the green tire while the green tire is held in the lower mold of the vulcanizer. Such an operation of closing the mold is controlled to a predetermined speed by the control of the vulcanizer side. In addition, the shape of the green tire and the profile of the mold (the shape of the tire after vulcanization) are different, and the timing of contact between the green tire and the mold in the process of closing the mold causes a time lag for each tire part. .. As a result, for example, a large force is applied to a portion that comes into contact with the mold at the initial stage of vulcanization, such as a bead portion, and the tire structural member may be disturbed, leading to deterioration of tire quality. Further, such a problem that the tire quality is deteriorated may also occur in the vulcanization method using a rigid core.

As such disturbance of the tire structural member, for example, in the grooved portion of the tread portion, as shown in FIGS. 5A and 5B, the cross-sectional shape of the tire structural member 30 such as the carcass layer, the belt layer, and the inner liner layer is formed. Disturbance occurs that is not uniform. When the mold 20 and the green tire G come into contact with each other during vulcanization, the tire structural member 30 moves in the tire width direction, especially in the grooved portion, and as a result, the cross-sectional shape is not uniform and the tire circumferential direction. Uniformity is also impaired.

On the other hand, in order to suppress the occurrence of various defects during vulcanization, a vulcanization method has been proposed in which the internal pressure is set low until the rubber flow is completed, focusing on the pressure difference in the internal pressure filling process at the initial stage of vulcanization. (For example, Patent Document 1). However, the pressure difference in the internal pressure filling process at the initial stage of vulcanization is greatly affected by the pressure difference generated in the process of closing the mold, so simply setting the internal pressure low until the rubber flow is completed is sufficient for the tire. There is a problem that deterioration of quality cannot be sufficiently suppressed.

Japanese Unexamined Patent Publication No. 2016-210136

An object of the present invention is to provide a tire vulcanization method capable of improving tire quality by controlling the closing speed of a mold according to a contact state between a green tire and a mold during tire vulcanization. There is.

The tire smelting method of the present invention for achieving the above object detects a contact state between the green tire and the mold in a method of smelting a tire using a mold having a molding surface that abuts on the green tire. A pressure sensor capable of measuring the contact pressure with the green tire is used, and the pressure sensor is provided at a position in the mold where the bead portion and / or the crown portion of the green tire abuts under the groove. When closing the mold while the green tire is held in the scouring apparatus, the speed at which the mold is closed is controlled according to the contact state between the green tire and the mold, and according to the output of the pressure sensor. When controlling the closing speed of the mold, if the output of the pressure sensor is large, the closing speed of the mold is slowed down, and if the output of the pressure sensor is low, the closing speed of the mold is increased. It is characterized by.

Furthermore, the tire vulcanizing method of the present invention is a method for vulcanizing a tire using a mold having a molding surface which contacts the green tire, in order to detect the contact state between the mold and the green tire, To a temperature sensor capable of measuring the surface temperature of the mold, a proximity sensor capable of detecting contact with rubber, a separation sensor capable of measuring the distance to the surface of the green tire, and a vent hole provided in the mold. Using any of the detectors that detect the amount of rubber flowing in, the sensor or detector is installed at a plurality of locations on the mold, and these sensors or detectors are evenly distributed over the entire molding surface of the mold. When the mold is closed while the green tire is held in the scouring apparatus, the speed at which the mold is closed is controlled according to the contact state between the green tire and the mold, and the sensor or the sensor or the mold is closed. When controlling the closing speed of the mold according to the output of the detector, when the contact area between the green tire and the mold is small, the closing speed of the mold is slowed down, and the green tire and the mold are closed. It is characterized in that the speed of closing the mold increases as the contact area with the mold increases.

In the tire vulcanization method of the present invention, when the mold is closed while the green tire is held in the vulcanizer, the speed at which the mold is closed is controlled according to the contact state between the green tire and the mold. For example, in the bead portion which is a portion that comes into contact with the mold at the initial stage of vulcanization, it is possible to adjust the closing speed of the mold so that the pressure or the like does not exceed a predetermined threshold value at the initial stage of vulcanization. As a result, the disorder of the tire structural member can be reduced, and as a result, the tire quality can be improved.

In the tire brewing method of the present invention, a pressure sensor capable of measuring the contact pressure between the green tire and the mold is used to detect the contact state between the green tire and the mold, and the speed at which the mold is closed is determined based on the output of the pressure sensor. It is preferable to control. This makes it possible to effectively improve tire quality.

In the tire vulcanization method of the present invention, a temperature sensor capable of measuring the surface temperature of the mold is used to detect the contact state between the green tire and the mold, and the speed at which the mold is closed is controlled based on the output of the temperature sensor. It is preferable to do so. This makes it possible to effectively improve tire quality.

In the tire vulcanization method of the present invention, a proximity sensor capable of detecting contact with rubber is used to detect the contact state between the green tire and the mold, and the speed at which the mold is closed is controlled based on the output of the proximity sensor. Is preferable. This makes it possible to effectively improve tire quality.

In the tire vulcanization method of the present invention, a separation sensor capable of measuring the distance to the surface of the green tire is used to detect the contact state between the green tire and the mold, and the mold is formed based on the output of the separation sensor. It is preferable to control the closing speed. This makes it possible to effectively improve tire quality.

In the tire vulcanization method of the present invention, the amount of rubber flowing into the vent hole provided in the mold to detect the contact state between the green tire and the mold is detected, and the speed at which the mold is closed is determined based on the amount of flowing. It is preferable to control. This makes it possible to effectively improve tire quality.

It is sectional drawing which shows the state which the mold of the tire vulcanization apparatus which concerns on embodiment of this invention is completely closed. It is sectional drawing which shows the state which the mold of the tire vulcanization apparatus which concerns on embodiment of this invention is in the process of closing. In the tire vulcanization method of the present invention, it is a graph which shows the relationship between the pressure measured at the position corresponding to each part of the green tire in a mold, the speed of closing a mold, and the elapsed time. It is a graph which shows the relationship between the pressure measured at the position corresponding to each part of the green tire in a mold, the speed of closing a mold, and the elapsed time in the conventional tire vulcanization method. (A) and (b) show the grooved portion of the tread portion of the green tire during vulcanization in the conventional vulcanization method, and (a) is a cross section showing the state before contact between the mold and the green tire. FIG. 6B is a cross-sectional view showing a state after contact between the mold and the green tire.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show a tire vulcanizer according to an embodiment of the present invention. As shown in FIGS. 1 and 2, the tire vulcanizer 1 includes a mold 2 for molding the green tire G.

The mold 2 has a configuration in which the mold 2 is divided into a plurality of parts in the vertical direction, and is used to form a pair of upper and lower side plates 3A and 3B for forming the sidewall portion of the green tire G and a bead portion of the green tire G. It is composed of an upper bead ring 4A and a lower bead ring 4B, and a plurality of sector molds 5 for forming the tread portion of the green tire G. The mold 2 is adapted to vulcanize the green tire G loaded in the cavity with the rotation axis in the vertical direction. At the time of vulcanization, a rubber bladder 6 formed into a cylindrical shape is inserted inside the green tire G.

The lower end of the bladder 6 is sandwiched between the lower bead ring 4B and the lower clamp ring 7B, and the upper end of the bladder 6 is between the upper clamp ring 7A and the auxiliary ring 8 which are configured to be movable in the vertical direction. It is sandwiched between. Therefore, when the mold is closed, the upper clamp ring 7A is arranged in the lower position to allow the bladder 6 to expand, while when the mold is opened, the upper clamp ring 7A moves to the upper position to allow the bladder from the inside of the green tire G. 6 is to be pulled out.

The tire vulcanizer is provided with a medium supply means (not shown) for introducing a heating and pressurizing medium inside the bladder 6, and the bladder 6 is vulcanized based on the pressure of the heating and pressurizing medium. The green tire G is pressed from the inside toward the inner surface of the mold 2. As the heating medium, for example, steam can be used, and as the pressure medium, for example, an inert gas such as nitrogen gas or steam can be used.

Platens 9 are arranged as heating means on the outside of the pair of upper and lower side plates 3A and 3B and the sector mold 5, respectively. The structure of these platens 9 is not particularly limited, but for example, a structure in which a cavity is provided inside and a heating medium such as steam is introduced into the cavity can be adopted.

In the tire vulcanizer, the mold 2 has a detection means 10 for detecting the contact state between the green tire G and the mold 2, and a speed S for closing the mold 2 according to the contact state detected by the detection means 10. It is provided with a control device 11 for controlling. The detecting means 10 is installed in the vicinity of the molding surface M of the mold 2, and can be arranged at an arbitrary location of the mold 2. The control device 11 is connected to the mold 2 (at least the upper side plate 3A), and controls the closing speed S with respect to the upper side plate 3A, the upper bead ring 4A, and the sector mold 5. In FIG. 2, the upper side plate 3A connected to the control device 11 moves inward in the tire width direction, and the sector mold 5 moves inward in the tire radial direction in conjunction with the movement, so that the mold 2 is closed. It has become like.

As the detecting means 10, for example, a pressure sensor capable of measuring the contact pressure with the green tire G can be used, and in addition, a temperature sensor capable of measuring the surface temperature of the mold 2 and contact with the rubber can be detected. A proximity sensor, a separation sensor capable of measuring the distance to the surface of the green tire G, or a detector for detecting the amount of rubber flowing into the vent hole provided in the mold 2 can be used. In any device, the speed S for closing the mold 2 is controlled based on the output of the device. In the aspects of FIGS. 1 and 2, a pressure sensor is adopted as the detection means 10, and the pressure sensor is installed at a position (a total of 4 locations) in contact with the bead portion and the sidewall portion of the green tire G in the mold 2. ..

When the pressure sensor is used, it is preferable to install it in the bead portion and / or the groove lower portion of the crown portion, which is a portion where the tire structural member is likely to be disturbed at the initial stage of vulcanization. Further, the pressure sensor may be installed at at least one place in the mold 2. The speed S for closing the mold 2 is controlled according to the output of the pressure sensor. For example, the speed S is slowed down when the output of the pressure sensor is large, and the speed S is increased when the output of the pressure sensor is small. Control.

When any of the temperature sensor, proximity sensor, distance measuring sensor, and detector is used, it is an object of the sensor or detector to detect the contact range between the green tire G and the mold 2. If the contact area between the green tire G and the mold 2 can be grasped, the speed S for closing the mold 2 can be controlled without using a pressure sensor. These sensors or detectors are preferably installed at a plurality of locations in the mold 2, and further, the plurality of sensors or detectors are evenly arranged with respect to the entire molding surface M of the mold 2. Is more preferable. When controlling the speed S for closing the mold 2 according to the output of such various sensors or detectors, for example, when the contact area between the green tire G and the mold 2 is small, the speed S is slowed down to reduce the contact area. The speed S is controlled to increase as the value increases.

The temperature sensor detects a temperature change at the time of contact between the mold 2 and the green tire G. When the mold 2 and the green tire G come into contact with each other, a temperature drop is detected.

The proximity sensor detects the contact between the green tire G and the molding surface M of the mold 2. As the proximity sensor, for example, a non-contact type or contact type proximity sensor such as an eddy current type or a capacitance type can be used. It is also possible to use a mechanical proximity sensor that detects the stroke of the spring vent mounted in the exhaust hole of the mold.

The separation sensor measures the distance between the surface of the green tire G and the molding surface M of the mold 2. As the separation sensor, for example, a laser sensor, an infrared sensor, an ultrasonic sensor, an image sensor, or the like can be used.

The detector that detects the amount of rubber flowing into the vent hole measures the length of the protrusion (spew) formed on the tire surface after the rubber flows into the vent hole of the mold 2 during vulcanization. When the mold 2 and the green tire G come into contact with each other, the protrusion length is detected.

When the green tire G is vulcanized using the tire vulcanizer described above, the green tire G is put into the mold 2, the bladder 6 is inserted inside the green tire G, and the inside of the bladder 6 is provided by a medium supply means. The green tire G is vulcanized by introducing a heating and pressurizing medium into the tire and heating the mold 2 from the outside by a heating means. In the present invention, in such a vulcanization step, when the mold 2 is closed while the green tire G is held in the tire vulcanization apparatus 1, the mold 2 is closed according to the contact state between the green tire G and the mold 2. 2 Controls the closing speed S.

A method of controlling the closing speed S of the mold 2 will be described in detail in comparison with a conventional tire vulcanization method. 3 and 4 show the pressure measured at the position corresponding to each part of the green tire in the mold in each of the tire vulcanization method of the present invention and the conventional tire vulcanization method, and the speed and course of closing the mold. It shows the relationship with time. In FIGS. 3 and 4, the vertical axis represents the pressure P and the velocity S, and the horizontal axis represents the elapsed time t. Further, the pressure measured at the position corresponding to the bead portion of the green tire in the mold is Pb (dotted line in the figure), and the pressure measured at the position corresponding to the sidewall portion of the green tire is Ps (shown). The internal pressure of the bladder is Pi (dotted chain line in the figure), and the speed at which the mold is closed is S (thick line in the figure).

In the conventional tire vulcanization method shown in FIG. 4, the speed at which the mold is closed is not changed from the start of vulcanization to the initial stage of vulcanization. Therefore, the pressure Pb of the bead portion, which is a portion that comes into contact with the mold at the initial stage of vulcanization, rises significantly, and the pressure difference between the pressure Pb of the bead portion and the pressure Ps of the sidewall portion becomes extremely large. Vulcanization proceeds while the pressure difference between these parts remains relatively large even after the internal pressure Pi of the bladder rises. In this case, the pressure difference in each portion affects the tire structural member in a bead portion, a grooved portion of the crown portion, or the like.

On the other hand, in the tire vulcanization method of the present invention shown in FIG. 3, the speed S for closing the mold 2 is changed from the start of vulcanization to the initial stage of vulcanization. In particular, with respect to the bead portion whose pressure rises in contact with the mold 2 at the initial stage of vulcanization, the speed S at which the mold 2 is closed so that the pressure Pb of the bead portion does not exceed a predetermined threshold value P1 at the initial stage of vulcanization. Is increasing or decreasing. As a result, the pressure difference between the pressure Pb of the bead portion and the pressure Ps of the sidewall portion can be reduced as compared with the conventional tire vulcanization method, and the pressure is relatively small even after the internal pressure Pi of the bladder 6 rises. The difference can be maintained.

As described above, in the present invention, the mold 2 constituting the tire vulcanizer 1 corresponds to the detection means 10 for detecting the contact state between the green tire G and the mold 2 and the contact state detected by the detection means 10. Since it has a control device 11 that controls the closing speed S of the mold 2, for example, in the bead portion which is a portion that comes into contact with the mold 2 at the initial stage of vulcanization, a pressure or the like is predetermined at the initial stage of vulcanization. It is possible to adjust the speed S for closing the mold 2 so as not to exceed the threshold value. As a result, the disorder of the tire structural member can be reduced, and as a result, the tire quality can be improved.

In the above-mentioned tire vulcanization method and tire vulcanization apparatus, the vulcanization method using a bladder has been described, but the present invention can also be applied to a vulcanization method using a rigid core.

1 Tire vulcanizer 2 Mold 3 Side plate 3A Upper side plate 3B Lower side plate 4 Bead ring 4A Upper bead ring 4B Lower bead ring 5 Sector mold 6 Bladder 7 Clamp ring 7A Upper clamp ring 7B Lower clamp ring 8 Auxiliary ring 9 Platen 10 Detection means 11 Control device G Green tire M Molded surface S Speed

Claims (6)

A pressure sensor capable of measuring the contact pressure between the green tire and the mold in order to detect the contact state between the green tire and the mold in the method of smelting the tire using a mold having a molded surface that contacts the green tire. Is provided at a position where the pressure sensor abuts on the bead portion and / or the lower groove portion of the crown portion of the green tire in the mold, and the mold is closed while the green tire is held in the brewer. When controlling the closing speed of the mold according to the contact state between the green tire and the mold, and controlling the closing speed of the mold according to the output of the pressure sensor, the pressure sensor A tire brewing method characterized by slowing the closing speed of the mold when the output is large and increasing the closing speed of the mold when the output of the pressure sensor is small. In a method of vulcanizing a tire using a mold having a molded surface in contact with a green tire, a temperature at which the surface temperature of the mold can be measured in order to detect a contact state between the green tire and the mold. A sensor, a proximity sensor that can detect contact with rubber, a separation sensor that can measure the distance to the surface of the green tire, and a detector that detects the amount of rubber flowing into the vent hole provided in the mold. Using either, the sensor or detector is installed at a plurality of locations on the mold, these sensors or detectors are evenly distributed over the entire molding surface of the mold, and the green tire is vulcanized. When closing the mold while holding the tire, the speed at which the mold is closed is controlled according to the contact state between the green tire and the mold, and the mold is closed according to the output of the sensor or detector. When controlling the closing speed, if the contact area between the green tire and the mold is small, the closing speed of the mold is slowed down, and as the contact area between the green tire and the mold increases, the mold A tire vulcanization method characterized by increasing the speed at which the mold is closed. A temperature sensor capable of measuring the surface temperature of the mold is used to detect the contact state between the green tire and the mold, and the closing speed of the mold is controlled based on the output of the temperature sensor. The tire vulcanization method according to claim 2. A proximity sensor capable of detecting contact with rubber is used to detect a contact state between the green tire and the mold, and the speed at which the mold is closed is controlled based on the output of the proximity sensor. The tire vulcanization method according to claim 2. A distance measuring sensor capable of measuring the distance to the surface of the green tire is used to detect the contact state between the green tire and the mold, and the speed at which the mold is closed is controlled based on the output of the measuring sensor. The tire vulcanization method according to claim 2 , wherein the tire is vulcanized. In order to detect the contact state between the green tire and the mold, the amount of rubber flowing into the vent hole provided in the mold is detected, and the speed at which the mold is closed is controlled based on the flowing amount. The tire vulcanization method according to claim 2.

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