Patent ID: 12194702

DETAILED DESCRIPTION

A rubber temperature measuring device and a rubber product manufacturing method according to an embodiment of the present technology will be described below based on embodiments illustrated in the drawings.

The embodiment of a rubber temperature measuring device1according to an embodiment of the present technology illustrated inFIGS.1to3is mounted on a vulcanization mold11of a tire attached to a vulcanization device15of the tire. The mold11includes a plurality of sector molds11a, an annular upper side mold11b, and an annular lower side mold11c. The sector mold11avulcanizes a shoulder portion g2and a tread portion g3of a green tire G, and the upper side mold11band the lower side mold11cvulcanize a side portion g1. The mold11is formed, for example, from aluminum or an aluminum alloy.FIG.1illustrates the mold11in an open state (the state before being closed).

An installation hole13having an opening portion13ais formed at a predetermined position of a molding surface12of the mold11. The installation hole13is formed in the molding surface12that forms a portion of at least one of the tire side portion g1, the tire shoulder portion g2, and the tire tread portion g3. Further, a communicating hole14that communicates with the installation hole13and extends to the outer surface of the mold11is formed in the mold11.

The vulcanization device15includes an upper plate16, a lower plate17, a segment18, a container ring19, and a center mechanism20. The upper surface of the upper side mold11bis attached to the lower surface of the upper plate16so as to face each other, and the lower surface of the lower side mold11cis attached to the upper surface of the lower plate17so as to face each other. The lower plate17is fixed to the ground base in an immovable state.

A center post20athat forms the center mechanism20is disposed in an annular center CL of the upper side mold11band the lower side mold11c. Disc-shaped clamp portions21are attached to the center post20aat intervals in the vertical direction. The upper and lower end portions of a cylindrical vulcanization bladder22are gripped by the respective clamp portions21.

The segments18are arranged in an annular shape about the center mechanism20(the center CL). The outer circumferential surface of the sector mold11ais attached to the inner circumference side of each of the segments18so as to face each other. The outer circumferential surface of each segment18has an inclined surface inclined upward from the outer circumference side toward the inner circumference side.

The annular container ring19is an annular body about the center mechanism20(the center CL) and moves up and down on the outer circumference side of the segments18arranged in an annular shape. When the container ring19moves up and down, the inner circumferential inclined surface of the container ring19and the outer circumferential inclined surface of each of the segments18make sliding contact with each other. When the outer circumferential surface of each segment18is pressed by the inner circumferential surface of the container ring19moving downward in a state in which each of the segments18is mounted on the lower plate17, each sector mold11amoves closer to the annular center CL together with the segment18.

The temperature measuring device1includes: a temperature sensor2and a biasing member8disposed in the installation hole13; a control unit9disposed outside the mold11; and a communication line10that extends into the communicating hole14and communicatively connects the temperature sensor2and the control unit9. In this embodiment, a tubular casing6that is fitted into the installation hole13is also provided, and the temperature sensor2and the biasing member8are inserted into the casing6. Note that the casing6may be optionally provided.

The temperature sensor2has a temperature detecting unit3athat is expanded in diameter at the tip end of a shaft part4and has flange portions5aand5bat a longitudinal intermediate portion and a rear end portion of the shaft part4. For example, an electrode or the like of a thermocouple is provided in the temperature detecting unit3a. The communication line10connected to the rear end portion of the shaft part4is electrically connected to the temperature detecting unit3a. The side surface of the temperature detecting unit3ais a tapered surface3bthat expands in diameter toward the tip end.

The temperature detecting unit3a, the shaft part4, and the flange portions5a,5bcan be formed from metal such as common carbon steel or non-metal such as ceramics. For example, these members (at least the temperature detecting unit3a) can be made of a material having a thermal conductivity of 50% or less than the material of the molding surface12so that the heat of the mold11is less likely to be transferred thereto.

The shape in a plan view of the temperature detecting unit3amay be circular, but the shape is not limited thereto, and the shape may be an elliptical shape or a polygonal shape. An outer diameter equivalent dimension d1(the long diameter in an elliptical shape and the diameter of a circumscribed circle in a polygonal shape) in a plan view of the temperature detecting unit3ais, for example, approximately 1.5 mm or greater and 3 mm or less.

The biasing member8is disposed between the flange portions5aand5b. In this embodiment, a coil spring is used as the biasing member8, and the shaft part4is in a state of being inserted into the coil spring. A heat shielding layer having a lower thermal conductivity than the material of the biasing member8can be coated on the surface of the biasing member8. Other known types of spring, bushing formed of an elastic material such as vulcanized rubber, or the like can be used as the biasing member8.

The casing6has a tip end opening portion7aand a rear end opening portion7c, the temperature detecting unit3ais disposed close to the tip end opening portion7a, and the flange portion5bis disposed close to the back end opening portion7c. The tip end opening portion7ahas a tapered surface7bthat expands in diameter toward the molding surface12. Specifically, the shaft part4is inserted through the rear end opening portion7c, and the flange portion5bis disposed outside the casing6. The flange portion5bis expanded in diameter more than the rear end opening portion7cand functions as a stopper that prevents the temperature sensor2from coming out of the tip end opening portion7aof the casing6.

This stopper structure can be formed, for example, by passing the flange portion5bthrough the rear end opening portion7cbefore the casing6is fitted into the installation hole13, and then contracting the rear end opening portion7cin diameter. Alternatively, the stopper structure can be formed by a method such as forcibly passing the flange portion5bthrough the rear end opening portion7cso that the rear end opening portion7cis temporarily expanded in diameter (elastically deformed) or the flange portion5cis temporarily compressively deformed (elastically deformed).

The casing6can also be formed of metal such as common carbon steel or non-metal such as ceramics. For example, the casing6can be made of a material having a thermal conductivity of 50% or less than the material of the molding surface12so that the heat of the mold11is less likely to be transferred thereto.

The casing6may have a cylindrical shape, but the shape is not limited thereto, and the shape may be an elliptical cylindrical shape or a polygonal cylindrical shape. An outer diameter equivalent dimension d2(the long diameter in an elliptical cylindrical shape and the outer diameter of a circumscribed circle in a polygonal cylindrical shape) in a plan view of the casing6is larger than the outer diameter equivalent dimension d1of the temperature detecting unit3aand, for example, is approximately 2 mm or greater and 4 mm or less.

The biasing member8comes into contact with the flange portion5aand the bottom surface of the casing6and constantly biases the temperature sensor2in a direction of projecting from the molding surface12. Due to the biasing force of the biasing member8, the temperature detecting unit3aprojects from the molding surface12and remains in a standby position in which the temperature detecting unit3ais not in contact with the mold11. A projection dimension h of the tip end surface of the temperature detecting unit3aprojecting from the molding surface12is, for example, 0.1 mm or greater and 1.0 mm or less.

A computer or the like having a calculating function and a storage function is used in the control unit9to which the temperature data detected by the temperature sensor2is input. An inner diameter d3of the communicating hole14is, for example, approximately, 0.5 mm or greater and 3 mm or less.

Next, an example of a method for manufacturing a pneumatic tire by vulcanizing the green tire G by the vulcanization device15while measuring the temperature of the green tire G, which is a molded article, using the temperature measuring device1will be described.

The main member constituting the green tire G is unvulcanized rubber and a reinforcing wire of metal or a resin. When the green tire G is vulcanized, the green tire G in a state of lying sideways is inserted through the center mechanism20in a state in which the mold11is open as illustrated inFIG.1. The green tire G is then held from the inner side by the bladder22inflated by the shaping pressure. The green tire G is placed on the lower side mold11cin a state of lying sideways.

Before the mold11is closed, as illustrated inFIG.2, the temperature detecting unit3aprotrudes from the molding surface12and is maintained in a standby position in which the temperature detecting unit3ais not in contact with the mold11. Thus, the temperature of the mold11is prevented from being directly transferred to the temperature detecting unit3abefore the mold11is closed.

Subsequently, the container ring19, the upper plate16, and the upper side mold11bare moved downward, and each of the segments18is placed on the lower plate17. The outer circumferential inclined surface of each segment18is pressed by the inner circumferential inclined surface of the container ring19moving downward, and each sector mold11ais moved toward the annular center CL together with the respective segments18.

As a result, as illustrated inFIG.4, the sector molds11aare assembled in an annular shape between the upper plate16and the lower plate17. Then, the sector molds11aare each vertically sandwiched between the upper side mold11band the lower side mold11cto close the mold11.

With the mold11closed, a heating medium such as steam and a pressurizing medium such as nitrogen gas are sequentially injected into the bladder22to heat and further inflate the bladder22. As a result, the inner side of the green tire G is mainly heated by the bladder22, and the outer side of the green tire G is mainly heated by the mold11. In this manner, the green tire G is heated and pressurized for a predetermined time in the closed mold11whereby a vulcanized tire is manufactured.

Since the green tire G is installed in the mold11and the mold11is closed, as illustrated inFIG.5, the green tire G makes contact with the temperature detecting unit3aand presses the temperature sensor2toward the deeper side of the installation hole13against the biasing force of the biasing member8. As a result, the opening portion13ais blocked by the temperature detecting unit3a.

Specifically, in this embodiment, the tapered surface7bof the tip end opening portion7aof the casing6comes into contact with the tapered surface3bof the temperature detecting unit3a, whereby the temperature detecting unit3ais positioned at a predetermined position in the opening portion13a, and the opening portion13ais blocked by the temperature detecting unit3a. In addition, the tip end surface of the temperature detecting unit3ais at an identical level to the molding surface12. Furthermore, since the temperature detecting unit3amakes firm contact with the green tire G (unvulcanized rubber) to be pressed, it is advantageous in accurately detecting the temperature of the green tire G (unvulcanized rubber) being in contact using the temperature sensor2. Since the temperature data detected by the temperature sensor2is input to the control unit9through the communication line10, the temperature of the unvulcanized rubber during vulcanization can be detected more accurately.

Since the opening portion13ais blocked by the temperature detecting unit3aduring vulcanization of the green tire G, the unvulcanized rubber constituting the green tire G can be prevented from flowing into the installation hole13. Therefore, the temperature sensor2can be used repeatedly, and no unnecessary spew is formed on the surface of the manufactured tire.

In this embodiment, the biasing member8and the temperature sensor2to which the communication line10is connected can be unitized in advance by inserting and incorporating the same into the casing6. Therefore, when the unitized casing6is fitted into the installation hole13, the attachment of the temperature sensor2and the like to the mold11is made easy. Furthermore, by strongly pulling the temperature detecting unit3aof the temperature sensor2disposed in the installation hole13toward the molding surface12, the temperature sensor2and the communication line10can be pulled out from the casing6. Thus, the replacement of the temperature sensor2and the like is made easy and maintainability is improved.

Since the temperature detecting unit3ais not in contact with the mold11before the mold11is closed, the temperature detecting unit3adoes not need to be surrounded by the heat shielding layer with a corresponding layer thickness in order to block the heat of the mold11as in the related art. Therefore, the outer diameter equivalent dimension d2of the casing6can be minimized to 4 mm or less or 3 mm or less. In other words, the area of the tip end surface of the temperature detecting unit3acan be made sufficiently small. Therefore, even if a complex pattern (such as recesses and protrusions that form a pattern in the tire) is formed on the molding surface12, it is advantageous in disposing the temperature detecting unit3a(the temperature sensor2) at a desired position on the molding surface12.

The shape of the tip end surface of the temperature detecting unit3ais not limited to a flat surface, and as illustrated inFIGS.6A-6B, the tip end surface can be appropriately formed in a desired shape. InFIGS.6A and6B, the tip end surface of the temperature detecting unit3ahas a conical shape and a hemispherical shape, respectively.

When the projection dimension h of the temperature detecting unit3afrom the molding surface12is increased in a state in which the opening portion13ais blocked by the temperature detecting unit3a, the temperature at a position deeper from the surface of the green tire G (unvulcanized rubber) can be detected. However, when the projection dimension h is increased, since a hole equivalent to the projection dimension h is formed in the manufactured tire, the projection dimension h is set in a range that does not affect the performance of the tire or the like.

As illustrated inFIG.7, the casing6of the temperature measuring device1may be omitted from the above-described embodiment. In this configuration, the flange portion5bis inserted into the communicating hole14, for example. The biasing member8comes into contact with the flange portion5aand the bottom surface of the installation hole13and constantly biases the temperature sensor2in a direction of projecting from the molding surface12. Other specifications may be similar to the above-described embodiment.

In the description described above, a case in which the green tire G is vulcanized to manufacture a tire has been described, but an embodiment of the present technology is not limited thereto. That is, the temperature measuring device1and the rubber product manufacturing method described above can be applied to a case where a molded article with unvulcanized rubber as a constituent member is disposed in a vulcanization mold and is vulcanized to manufacture a rubber product.