JP2013224102A - Flap for tire and method of manufacturing flap for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flap for a tire capable of reducing damage by rubbing to a tube of a peripheral end part of a wing part of the flap.SOLUTION: A flap 1 for a tire is a flap for a tire installed in a tube of a tube type tire, and includes a cylindrical base part 1a installed between the tube and a rim, and a pair of wing parts 1b continuously connected to both sides of the base part 1a. The peripheral end part of the wing part 1b of the flap is formed in a shape of continuously changing in a wave shape between the most distant position and the nearest position in a distance from the axis of the base part 1a. Therefore, even when the flap 1 is dislocated in the peripheral direction to the tube, a position of rubbing the peripheral end part of the wing part 1b with the tube is always changed.

Description

  The present invention relates to a tire flap that is used in contact with a tube mounted inside a tire and a method for manufacturing the tire flap.

  A pneumatic tire is generally composed of a plurality of members made of cords such as steel and organic fibers, rubber, and the like, and a plurality of types of rubber members that are different for each part depending on the performance required for each part of the tire. Is used. For example, in the case of a tube-type tire, the bead toe that is the tip of the bead portion is lifted from a rim wheel (hereinafter abbreviated as “rim”), which may cause a gap between the bead toe and the rim, and the tube may enter. There is. When the tube is sandwiched between the bead toe and the rim, there is a problem that the tube is damaged and punctures in the worst case.

  In order to cope with such a problem, a flap, which is a rubber member, is inserted between the bead portion and the tube so that the tube does not enter between the bead toe and the rim. FIG. 9 is a cross-sectional view in the width direction regarding a conventional tube-type tire. The tubular tire 100 has a rim 101 fitted in the center of the tire body. The tire body includes a pair of bead portions 102 attached to the rim 101, a pair of sidewall portions 103 connected to the bead portion 102, and A tread portion 104 that connects the sidewall portions 103 is provided. A tube 105 is accommodated inside the tire body, and a flap 106 is provided between the bead portion 102 and the rim 101 of the tire body and the tube 105. A tube 107 is attached to the tube 105 through the rim 101 and the flap 106, and is filled with high-pressure air through the valve 107.

  The flap 106 includes a cylindrical base portion 106 a that is mounted between the rim 101 and the tube 105, and a pair of wings that are extended between both sides of the base portion 106 a and are mounted between the bead portion 102 and the tube 105. Part 106b. FIG. 10 is a side view showing a state in which the conventional flap 106 is attached to the tube 105. A peripheral end portion of the wing portion 106 b of the flap 106 is formed in a circular shape and is in close contact with the peripheral surface of the tube 105. When the tire is in use, the flap 106 is displaced with respect to the tube 105. However, since the peripheral end of the wing 106b is circular, the peripheral end of the wing 106b is on the same circumference of the peripheral surface of the tube 105. Acts like rubbing against. For this reason, the tube 105 where the peripheral end of the wing 106b contacts is constantly rubbed, resulting in damage due to wear. In particular, since the tube 105 tends to be damaged when the peripheral end portion of the wing portion 106b is formed thick, when the peripheral end portion of the wing portion 106b is thicker than a predetermined value, the peripheral end portion If the thick part of the material is buffed to make it thinner, or if it cannot be corrected, it is considered a defective product.

  Patent Document 1 describes that a metal layer is provided between a flap shoulder portion and a rim that curve toward the outer side in the tire radial direction of the flap in order to reduce damage to the tube.

JP 2009-214834 A

  Then, an object of this invention is to provide the manufacturing method of the flap for tires, and the tire flap which can reduce the damage by the abrasion with respect to the tube of the peripheral edge part of the wing part of a flap.

  A tire flap according to the present invention is a tire flap mounted on a tube of a tube-type tire, and is connected to a cylindrical base portion mounted between the tube and a rim, on both sides of the base portion. A pair of wing portions, and a peripheral end portion of the wing portion is formed in a shape in which the distance from the central axis of the base portion continuously changes.

  The present invention can reduce damage caused by rubbing against the tube at the peripheral end portion of the wing portion of the flap by having the above-described configuration.

It is the side view and external appearance perspective view regarding the flap for tires which are embodiment which concerns on this invention. It is a partially expanded side view which shows the state which mounted | wore the tube with the flap. It is sectional drawing regarding the shaping | molding die which shape | molds the flap for tires. It is a partially expanded sectional view regarding the shaping | molding part of a wing part. It is explanatory drawing of the parameter regarding the flap for tires. It is explanatory drawing of the parameter regarding a shaping | molding die. It is a table | surface regarding the numerical value of the parameter set in the comparative example and the Example. It is a table | surface which shows an evaluation result. It is sectional drawing of the width direction regarding the conventional tube type tire. It is a side view which shows the state which mounted | wore the conventional flap to the tube.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view (FIG. 1 (a)) and an external perspective view (FIG. 1 (b)) of a tire flap 1 according to an embodiment of the present invention. The tire flap 1 includes a cylindrical base portion 1a and a pair of wing portions 1b connected to both sides of the base portion 1a. And the peripheral edge part of the wing part 1b is set so that the distance d from the central axis O of the base part 1a may change continuously. In this example, the distance is set so as to periodically change in a wave shape between the distance d ₁ farthest from the center axis O and the distance d ₂ closest to the center axis O. FIG. 2 is a partially enlarged side view showing a state where the flap 1 is attached to the tube 2. When the flap 1 is attached to the tube 2 and the flap 1 is displaced in the circumferential direction with respect to the tube 2 as indicated by the dotted line, the peripheral end of the wing 1b of the flap 1 continuously changes in a wave shape. The location where the wing portion 1b of the tube 2 is in contact changes continuously. For this reason, since there is no portion that is always in contact with the wing portion 1b, damage to the tube 2 caused by rubbing the peripheral end portion of the wing portion 1b can be reduced as compared with the case where the wing portion 1b is constantly rubbed.

  In the example described above, the shape of the peripheral end portion of the wing portion 1b is formed so as to periodically change in a wave shape, but is formed so that the distance from the central axis O changes continuously. There is no particular limitation as long as it is sufficient.

  FIG. 3 is a cross-sectional view of a mold for molding the tire flap according to the present embodiment. The molding die 10 is configured by combining an upper die 11, a middle die 12 and a lower die 13, and a space portion 14 in which a flap is molded is formed inside the die so as to join each die. . The flaps are produced by a press vulcanization method in which a mold is filled with unvulcanized rubber and vulcanized, and an unvulcanized rubber is wrapped around a cylindrical molding ring (drum) in an oven. An open vulcanization method in which vulcanization is performed is known. In addition to this, a manufacturing method called an injection method using an injection mold is also known. Although this method can manufacture the flap with high accuracy, it is not widely used because the equipment is expensive.

  In order to mold the peripheral end of the wing portion 1b of the flap 1, the split position 12a where the upper mold 11 (or the lower mold 13) and the middle mold 12 are joined is changed from the molding position 12b of the peripheral end of the wing section to the upper mold. 11 (or lower mold 13) is set to be shifted. By setting in this way, it becomes possible to shape | mold thinly the thickness of the peripheral edge part of the wing part in the shaping | molding position 12b, and it can form stably to the thickness of 0.5 mm or less.

FIG. 4 is a partially enlarged cross-sectional view relating to a molded part of the wing part. In the preparation of the peripheral edge portion of the wing portion so as to continuously change the wave shape as shown in FIG. 1, the closest distance between the molding position 12b corresponding to the greatest distance d ₁ from the center axis O shown in FIG. 1 It will be set continuously deviation between the molding position 12d corresponding to d _2. Therefore, set successively deviated between the split position 12c corresponding to the nearest distance d ₂ and split position 12a also corresponds to the greatest distance d ₁ split position for joining the mold.

  In the case of forming a space portion for forming the wing portion, the intermediate mold 12 is separately manufactured at a separation position 12e where the intermediate mold 12 is separated at the molding position 12b. The separation position 12 e is set so as to be separated along the inner surface 11 a of the upper mold 11. Then, on the surface 12f facing the inner surface 11a of the upper mold 11 of the middle mold 12, a mold that is embossed according to the continuously changing shape and thickness of the peripheral end of the wing is formed. Therefore, by joining and fixing the divided parts separated at the separation position 12e, the space portion can be formed with a desired shape and thickness at the molding positions 12b and 12d. In the above description, the joint portion between the upper die 11 and the middle die 12 has been described. However, the joint portion between the lower die 13 and the middle die 12 is configured similarly.

  In this way, by integrally forming the shape for forming the peripheral edge of the wing part of the flap in the middle mold 12, when the amount of material used for vulcanization is large or when the pressure for clamping the mold is small Even under various manufacturing conditions, it is possible to stably form a desired thin peripheral end portion while suppressing variations in the edge shape of the peripheral end portion. Moreover, since the shape of the peripheral edge part of the wing part of a flap can be continuously changed and formed thinly, it becomes possible to reduce damage to the tube when it is attached to the tube. In addition, since the thickness of the peripheral end portion of the wing portion can be uniformly formed, the rigidity of the peripheral end portion can be ensured, and a flap that is difficult to tear can be obtained.

A conventional rubber material was used as the flap molding material, and the flap was molded by filling the mold shown in FIG. In the molding, Examples 1 to 6 were set by changing the shape of the flap and the parameters of the mold. As shown in FIG. 5, the shape of the flap is such that the difference Δd between the farthest distance d ₁ and the nearest distance d ₂ of the peripheral end of the flap wing 1b from the center axis O of the flap base 1a and both The angle θ ₁ between the positions is changed as a parameter, and the predetermined curve shape that continuously changes between the farthest distance position and the nearest distance position is preferably formed into a wave shape, more preferably It is better to form a sine wave. As for the mold, as shown in FIG. 6, the shape of the flap therebetween as the length Δd between the molding position 12d corresponding to the nearest distance d ₂ and the molding position 12b corresponding to the farthest distance d ₁ It was set as the curve shape corresponding to. The length d ₃ from the molding position 12b to the split position 12a (or the molding position 12d to the split position 12c) was changed as a parameter. In addition, as a comparative example, as shown in FIG. 10, a flap having a circular wing end is used. In addition, in the comparative example, it shape | molded using the conventional shaping | molding die in which the separation position 12e shown in FIG. 6 was set to the split position. Comparative Examples and Examples 1 to 6 in .theta.1, [Delta] d and d ₃ are shown in the table of FIG.

The peripheral edge shape of the wing part of the molded flap was evaluated. In the evaluation method, the thickness of the wing part of the product flap was measured with calipers, and it was confirmed whether or not the thickness was 0.5 mm or less. Moreover, the presence or absence of defects such as other rubber flow defects was visually confirmed, and the evaluation results were evaluated in five stages. Next, using a tube-type tire assembled with a molded flap attached to the tube, the drum durability performance test stipulated in the US Automotive Safety Standards (FMVSS) was tested, and the tube surface obtained in the durability test The damage was evaluated. The evaluation method measured the number of places where the scratches occurred and the length of the scratches, and evaluated the evaluation results in five stages. The score was lowered as the number of scratches increased and the length of the scratches increased. The evaluation results are shown in FIG.
Looking at the evaluation results, in Examples 1 to 6, better results than the comparative example are obtained. In Example 4, when the length from the molding position corresponding to the peripheral edge of the wing part to the split position becomes longer, a part where the rubber material is not filled up to the molding position is found, and the evaluation is lower than in the other examples. However, when compared with the comparative example, good molding results could be obtained. Further, since the angle theta ₁ Example 6 is set to 90 degrees, although evaluation of the damage to the tube is lower than the other embodiments, it is possible to suppress the damage of the tube as compared with the comparative example did it.
From these evaluation results, when reducing damage to the tube, a flap in which Δd is set to 5 mm to 20 mm and θ ₁ is set to 15 degrees to 45 degrees is more preferable. It is more preferable that ₃ is set to 5 mm to 8 mm.

  DESCRIPTION OF SYMBOLS 1 ... Flap, 1a ... Base part, 1b ... Wing part, 2 ... Tube, 10 ... Mold, 11 ... Upper mold, 12 ... Middle mold, 12a ... Split position, 12b ... molding position of the peripheral end, 13 ... lower mold.

Claims (5)

  A tire flap mounted on a tube of a tube-type tire, comprising a cylindrical base portion mounted between the tube and a rim, and a pair of wing portions connected to both sides of the base portion. The peripheral edge of the wing part is a tire flap formed in a shape in which the distance from the central axis of the base part changes continuously.   2. The tire flap according to claim 1, wherein a shape of a peripheral end portion of the wing portion continuously changes in a wave shape.   The shape of the peripheral edge of the wing is such that the difference between the position farthest from the center axis and the position of the nearest distance is set to 5 mm to 20 mm, and the position farthest from the center axis The tire flap according to claim 1 or 2, wherein an interval between positions at a short distance is set to an angle of 15 degrees to 45 degrees.   It is a manufacturing method of the flap for tires in any one of Claim 1 to 3, Comprising: The shaping | molding position corresponding to the peripheral edge part of the said wing part while combining the some type | mold and forming the space part corresponding to the shape of the said flap Is formed with a single mold, the mold split position is set at a position deviated from the molding position, and the space portion is filled with a rubber material having fluidity and molded.   The method for manufacturing a tire flap according to claim 4, wherein a length between the molding position and the split position is set to 5 mm to 8 mm.

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