JP5175772B2 - Tire mold - Google Patents

Description

  The present invention relates to a tire molding die for vulcanizing a tire, and more particularly to a tire molding die in which a plurality of sectors in which a plurality of pieces are incorporated on the inner surface side of a back segment constitute a tread mold portion. It is.

  Tire molding dies are configured by combining a plurality of mold parts, and are roughly classified into a two-piece type and a segmented type based on the division form. In the latter type, the tread mold portion that contacts the tread surface of the tire is composed of a plurality of sectors divided in the tire circumferential direction, and an uneven shape corresponding to the tread pattern is provided on the inner peripheral surface of each sector. The sectors arranged on the circumference are separated from each other when the mold is opened, and gather together to form an annular shape when the mold is clamped.

  There are two types of segmented type molds: one is the monolithic integral molding of the inner periphery of the sector, and the other is a type in which multiple sectors are incorporated on the inner surface of the back segment, and the latter is a piece mold. Sometimes called. In the piece mold, air can be discharged out of the mold through the gap between the pieces, so there is no need to set a vent hole on the inner peripheral surface of the sector, thereby removing the rubber protrusion formed on the tread surface of the tire Can be reduced, and a tire having a good appearance without a cut mark can be manufactured.

  However, if the gaps between the pieces are not uniformly formed and the bias occurs, the rubber overflows at a location where the gaps are excessive, and rubber burrs are generated on the tread surface after molding. In this case, a rubber burr cutting operation is required, and the advantages of the piece mold are impaired. On the other hand, in a portion where the gap is excessively small, the air existing between the inner peripheral surface of the sector and the tread surface is not smoothly discharged out of the mold, and a dent scratch called a bear occurs on the tread surface. As described above, in the piece mold, it is very important to uniformly adjust the gap between the pieces with an appropriate size.

  Patent Document 1 below describes a tire molding die in which an elastic member such as a leaf spring or a coil spring is interposed between pieces, thereby adjusting a gap between pieces. In this mold, when the mold is opened, the pieces are separated from each other by the biasing force of the elastic member, and when the mold is clamped, the pieces are brought close to each other against the biasing force of the elastic member. Along with this, it is said that the gap between pieces can be easily adjusted.

  However, in practice, the gap between pieces must be adjusted to the order of several tens of μm. In order to control the gap between pieces using the above molding die, the back segment, piece, and elastic member The requirements for dimensional accuracy and assembly accuracy are quite severe, and in many cases, rubber burrs and bears are actually generated. For this reason, it cannot be said that the mechanism for adjusting the gap between pieces functions sufficiently stably, and a proposal for a further improvement method has been strongly desired.

  On the other hand, in Patent Document 2 below, a tire molding die in which each piece incorporated in a back segment is constituted by a molded part made of an iron-based alloy and a support part made of a material different from the iron-based alloy. Is described. In addition, there is a description that the support portion is formed of a material having a larger thermal expansion coefficient than the iron-based alloy of the forming portion, and an air vent slit is formed in the forming portion by heating at the time of vulcanization molding.

  However, in the above-described molding die, each piece has a two-layer structure of a molding part and a support part independently, and a force of pressing each other between adjacent support parts acts during heating. (See paragraph 0058, FIG. 18). In this way, with the structure in which the support part expands and pushes each other for each piece, the piece is prone to rattling and galling in the process of repeated expansion and contraction as the mold opens and closes, and the gap between pieces is uniform. There is concern that it will not be adjusted. As used herein, galling refers to a phenomenon where a piece is caught by another piece or back segment.

  In Patent Document 3 below, the thermal expansion coefficients of the members constituting the pieces are made different from each other, a slit having a sufficient width is formed using the difference in thermal expansion during vulcanization molding, and air is discharged from the slit. Thus, a tire molding die that suppresses bear is described. However, this molding die adjusts the gap between the main body of the piece and the core incorporated therein, and does not suggest a solution for the adjustment of the gap between the pieces.

JP 2006-159669 A JP 2004-230658 A JP 2008-114475 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tire molding die capable of uniformly adjusting the gap between pieces in accordance with the opening / closing operation of the die.

The above object can be achieved by the present invention as described below. That is, in the tire molding die according to the present invention, the tread mold portion that contacts the tread surface of the tire includes a plurality of sectors divided in the tire circumferential direction, and the sector is divided into a plurality of sectors divided in the tire circumferential direction. In a tire molding die configured to incorporate a piece on the inner surface side of the back segment, the sector includes a gap adjusting member extending in the tire circumferential direction so as to straddle a plurality of pieces, and the gap adjusting member, It is made of a material that is fixed to each of the straddling pieces and has a larger coefficient of thermal expansion than that of the pieces . When cold, adjacent pieces in the tire circumferential direction come into contact with each other and there is substantially no gap between the pieces. It is set to be in a state .

  According to the tire molding die of the present invention, the gap adjusting member expands larger than the pieces by heating at the time of vulcanization molding, thereby forming a gap between the pieces. At this time, since each piece moves so as to be pulled by the gap adjusting member, the force of pressing each other between the pieces does not act, and the occurrence of looseness and galling of the pieces can be suppressed. As a result, with the opening and closing operation of the mold, the gap between pieces can be easily adjusted to a uniform and non-biased state.

  In the tire molding die of the present invention, it is preferable that the gap adjusting member is incorporated on the inner surface side of the back segment in a state of being fixed to the back surface of the piece. According to this configuration, the gap adjusting member can be easily configured, and a piece to which the gap adjusting member is fixed can be incorporated by a simple shape change with respect to the existing back segment.

  In the tire molding die of the present invention, the gap adjusting member spans from a piece located at one end of the sector in the tire circumferential direction to a piece located at the other end, and to all the pieces included in the sector. What is fixed is preferable. In such a configuration, since the gap adjusting member is disposed across all the pieces included in the sector, the gap between the pieces can be easily and reliably adjusted without any excess.

The tire forming mold of the present invention, at the time of cold it is configured so that a gap between the pieces in contact piece to each other those adjacent in the tire circumferential direction is not state substantially. Thereby, the design specifications may be determined so that the pieces are separated from each other by the size of the gap formed between the pieces, and the adjustment of the gap between the pieces becomes easier. Examples of the design specifications include the peripheral length and thermal expansion coefficient of the piece and the gap adjusting member. Moreover, the cold time said here points out the non-heating normal temperature state before vulcanization molding.

  In the tire molding die of the present invention, it is preferable that the gap adjusting member is formed monolithically by a single part. Thereby, while being able to comprise a clearance gap adjustment member simply, expansion of the clearance gap adjustment member can be more reliably used for clearance gap adjustment between pieces.

1 is a longitudinal sectional view schematically showing an example of a tire molding die according to the present invention. Top view of the tread mold Perspective view of the sector (A) End face of sector and (B) Inner peripheral surface of sector Diagram showing the inner peripheral surface of the sector during heating The figure which shows the end surface of (A) sector which concerns on another embodiment, and the internal peripheral surface of (B) sector The figure which shows the end surface of (A) sector which concerns on another embodiment, and (B) the B arrow view

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view schematically showing an example of a tire molding die according to the present invention, and shows a clamped state. In FIG. 1, a green tire (not shown) is set so that the tire axial direction is up and down. That is, the right side in FIG. 1 is the inside in the tire radial direction, and the left side in FIG. 1 is the outside in the tire radial direction. FIG. 2 is a plan view of the tread mold portion 1 provided in the tire molding die.

  The tire molding die (hereinafter, sometimes simply referred to as “molding die”) includes a tread mold portion 1 with which a tread surface of the tire abuts, a side mold portion 2 with which a lower sidewall portion abuts, It is a segmented mold provided with the side type | mold part 3 with which an upper side wall part contact | abuts. A bead ring 4 is provided on the inner side in the tire radial direction of the side mold part 2 and the side part 3 and is configured to be able to fit the bead part of the tire.

  As shown in FIG. 2, the tread mold portion 1 includes a plurality of sectors 5 divided in the tire circumferential direction, and each of the sectors 5 is configured to be displaceable in the tire radial direction. In the mold-clamping state, the sectors 5 gather near each other and end surfaces are brought into contact with each other in an annular shape, whereas in the mold-opening state, the sectors 5 are radially displaced and separated from each other. In the present embodiment, an example is shown in which the tread mold part 1 is divided into seven parts and the circumferences of the sectors 5 are substantially equal. However, in the present invention, the number of divisions of the tread mold part is not particularly limited, and The lengths may be different from each other.

  A container 21 is attached to the back surface of the tread mold portion 1. The container 21 is provided for each sector 5 and is slidably attached along the tire radial direction on the lower surface of a side plate 23 fixed to a lifting cylinder (not shown). A slide rail 25 is provided on the outer slope of the container 21, and a cone ring 24 is slidably fitted along the inclined direction. The cone ring 24 is supported from above by a platen (not shown) that can move up and down relatively with respect to the side plate 23.

  In the state shown in FIG. 1, when the cone ring 24 is raised and the container 21 is moved outward in the tire radial direction, each sector 5 can be separated from the side mold portions 2 and 3, and the side plate 23 and the container 21 are further moved by the lifting cylinder. Is raised, the sector 5 and the side mold part 3 can be separated from the side mold part 2 and shifted to the mold open state. The transition from the mold opening state to the mold clamping state may be performed by reversing the above operation.

  FIG. 3 is a perspective view of the sector 5. FIG. 4 is a diagram showing an end face and an inner peripheral face of the sector 5. The sector 5 is configured by incorporating a plurality of pieces 6 divided in the tire circumferential direction on the inner surface side of the back segment 7. Although not shown, the inner peripheral surface of the sector 5 (the inner peripheral surface of each piece 6) is provided with an uneven shape corresponding to the tread pattern. In the present embodiment, the sector 5 includes five pieces 6 and the boundary between the pieces 6 is formed as a zigzag non-planar surface. However, the number of pieces is not limited to this, and the boundary between the pieces is not limited to this. May be formed in a plane.

  The piece 6 is fitted into the recessed portion 7a on the inner surface side of the back segment 7, and is supported from the outer side in the tire width direction (vertical direction in FIGS. 3 and 4) by the arm portion 7b of the back segment 7. A slight clearance is provided between the piece 6 and the back segment 7, and the piece 6 is configured to be slidable along the tire circumferential direction. In this molding die, since the gap between the pieces 6 can be adjusted uniformly as described later, no elastic member is interposed between the pieces 6.

  The constituent material of the piece 6 is not particularly limited, but an aluminum material is common. This aluminum material is a concept that includes not only a pure aluminum material but also an aluminum alloy. For example, Al-Cu, Al-Mg, Al-Mg-Si, Al-Zn-Mg, Al-Mn System and Al-Si system. Since the piece 6 made of an aluminum material may be deformed when galling occurs, the present invention that can suppress galling of the piece 6 is particularly useful. The constituent material of the back segment 7 is exemplified by a steel material.

  The sector 5 includes a gap adjusting member 8 extending in the tire circumferential direction so as to straddle the plurality of pieces 6. The gap adjusting member 8 is longer than the piece 6 in the tire circumferential direction, and is fixed to each of the straddling pieces 6 and is made of a material having a larger coefficient of thermal expansion than the piece 6. The means for fixing the piece 6 and the gap adjusting member 8 is not particularly limited, but bolts and nuts are simple and preferable. The gap adjusting member 8 is a columnar body extending in an arc shape along the tire circumferential direction, and is incorporated on the inner surface side of the back segment 7 while being fixed to the back surface of the piece 6. A dovetail groove for fitting the gap adjusting member 8 is formed in the recessed portion 7a.

  When the tire is vulcanized and molded, the molding die is heated to a vulcanization temperature (for example, around 170 ° C.), thereby causing each member to thermally expand. At this time, since the gap adjusting member 8 is made of a material having a larger thermal expansion coefficient than that of the piece 6, the piece 6 having a relatively small thermal expansion moves so as to be pulled by the gap adjusting member 8, and is shown in FIG. Thus, a gap G is formed between the pieces 6. The arrow of FIG. 5 has shown the direction of the force which acts on each piece 6 when it sees on the basis of the piece 6 in the middle. Since the force which mutually presses between pieces 6 does not act, generation | occurrence | production of a backlash and a galling is suppressed, and the clearance gap G can be adjusted to the state which is uniform and non-biased.

The size of the gap G after heating is set to, for example, 0.015 to 0.04 mm so as to prevent the rubber from overflowing and discharge the air. For this gap G, the following calculation formula is established. Where Ls: circumference of the inner peripheral surface per sector, Lp1: circumference of a piece located on one side of the gap, Lp2: circumference of a piece located on the other side of the gap, T: temperature rise, α1: The thermal expansion coefficient of the pieces, α2: the thermal expansion coefficient of the gap adjusting member, and n: the number of pieces per sector.
Formula: G = (Ls− (Lp1 + Lp2) / 2) × T × (α2−α1) / (n−1)

Therefore, in the above case, if Ls = 300 mm, Lp1 = Lp2 = 37.5 mm (all equal pitches), T = 150 ° C. (temperature rise from 20 ° C. to 170 ° C.), and n = 8, (α2−α1) Is set in the range of 2.67 × 10 ^{−6 to} 7.11 × 10 ⁻⁶ . When ADC14 (α1 = 19 × 10 ⁻⁶ / ° C.) is adopted as the material of the piece 6 and ADC5 (α1 = 26 × 10 ⁻⁶ / ° C.) is adopted as the material of the gap adjusting member 8, (α2− It is considered that α1) is 7 × 10 ⁻⁶ / ° C. and a gap G of 0.039 mm is obtained. ADC14 and ADC5 are aluminum alloy die castings specified in JIS H 5302: 2006, respectively.

  The above-described calculation formula is based on the premise that there is substantially no gap between the pieces 6 when cold. That is, as shown in FIG. 4, when cold, pieces 6 adjacent to each other in the tire circumferential direction are in contact with each other with their end faces abutted, and there is substantially no gap between pieces 6. . In this case, since it is not necessary to consider the gap between the pieces 6 before heating, design specifications are easily determined, and the adjustment of the gap between the pieces 6 becomes easier.

  After the vulcanization of the tire is completed, the mold is opened and the vulcanized tire is taken out, and a new green tire is set and the mold is clamped, and this is repeated. The expansion and contraction of each member is repeated with the opening and closing of the mold, but in this molding mold, the force that the pieces 6 press against each other does not act, so that the pieces 6 can be prevented from rattling or galling. As a result, the gap between the pieces 6 can be adjusted uniformly with the opening and closing operation of the mold.

  In the present embodiment, the gap adjusting member 8 extends from the piece 6 positioned at one end in the tire circumferential direction of the sector 5 to the piece 6 positioned at the other end. In the embodiment, it is fixed to five pieces 6. Thereby, with respect to all the pieces 6 with which the sector 5 is provided, the clearance gap between the pieces 6 can be adjusted easily and reliably without leaving.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention, and the shape of the piece and the back segment can be appropriately changed. .

[Other Embodiments]
(1) In the above-described embodiment, an example in which one gap adjusting member 8 is provided at the center in the tire width direction has been shown. However, as in the sector 5 shown in FIG. A plurality of (two in the illustrated example) gap adjusting members 9 may be provided. According to this configuration, since the movement of the piece 6 can be suppressed by suppressing the inclination of the piece 6 with respect to the tire width direction, the adjustment of the gap between the pieces 6 accompanying the opening / closing operation of the mold can be performed with high accuracy.

  (2) In the above-described embodiment, the sector 5 includes the gap adjusting member 8 formed monolithically by a single component. However, in the tire molding die of the present invention, the gap adjusting member includes a plurality of gap adjusting members. As long as it arrange | positions so that it may straddle a piece, the clearance gap adjustment member may be comprised combining several members. The configuration of the gap adjusting member is selectively used depending on the size of the molding die.

  In the sector 5 shown in FIG. 7, gap adjusting members 10 made of chain-like connected objects are fixed to the upper and lower slope portions of the piece 6. The gap adjusting member 10 is formed by integrally connecting a plurality of metal pieces 10a straddling a pair of adjacent pieces 6 with bolts 10b, and is fixed to the pieces 6 through the bolts 10b. In the case of fixing to the slope portion of the piece 6, such a structure is useful because the gap adjusting member is difficult to be manufactured if it is a monolithic monolith.

1 Tread type part 5 Sector 6 Piece 7 Back segment 8 Clearance adjusting member

Claims (4)

The tread mold portion that contacts the tread surface of the tire is composed of a plurality of sectors divided in the tire circumferential direction, and the sector is configured by incorporating a plurality of pieces divided in the tire circumferential direction on the inner surface side of the back segment. In tire molding molds,
The sector includes a gap adjusting member extending in the tire circumferential direction so as to straddle a plurality of pieces, and the gap adjusting member is fixed to each of the straddling pieces and is more thermally expanded than the pieces. A tire molding die, which is made of a material having a high rate and is set so that adjacent pieces in the circumferential direction of the tire come into contact with each other in the cold state so that there is substantially no gap between the pieces .   The tire molding die according to claim 1, wherein the gap adjusting member is incorporated on the inner surface side of the back segment in a state of being fixed to the back surface of the piece.   The gap adjustment member extends from a piece located at one end of the sector in the tire circumferential direction to a piece located at the other end, and is fixed to all the pieces included in the sector. The tire molding die described in 1. The tire molding die according to any one of claims 1 to 3, wherein the gap adjusting member is formed monolithically by a single component.

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