JP2001030254A - Large-sized tire for construction vehicle and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a large-sized tire of high quality for a construction vehicle in a highly efficient manner. SOLUTION: Since an unvulcanized tire 41 is fed while grasped by inserting feed pawls 57 in the peripheral groove formed to a tread part 25 large in weight, the load applied to a side wall part 24 becomes little and, as a result, the sagging deformation of the unvulcanized tire 41 during feed is effectively suppressed. The feed pawls 557 are pulled out of the peripheral groove 42 rapidly and simply because the pawls may be moved over a distance slightly longer than the groove depth of the peripheral groove 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large tire for a construction vehicle capable of suppressing deformation during transportation and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, large tires for construction vehicles are manufactured by molding an unvulcanized tire using, for example, a tire forming drum.
The unvulcanized tire is taken out of the tire building drum, and then, while shaping the bead portion of the unvulcanized tire from the inside in the radial direction, filling the unvulcanized tire with an internal pressure and adjusting its shape. After that, the shaping mechanism is transported together with the unvulcanized tire to a vulcanization mold and housed in the vulcanization mold, and then manufactured by vulcanizing the unvulcanized tire with a vulcanization mold. ing.

[0003]

Here, as shown in FIG. 7, the unvulcanized tire is transported by suspending a shaping mechanism 12 holding a horizontal unvulcanized tire 11 with a crane or the like. The unvulcanized tire 11 is large and heavy for construction vehicles, and in recent years, the tread portion 13 has been used to extend the wear life.
Since the rubber gauge of the tread portion 13 is made thick, the weight of the tread portion 13 is extremely large, and as a result, during the transportation, the sidewall portion 14 hangs down as indicated by a virtual line due to the weight of the tread portion 13. It will be deformed.

The uncured tire thus deformed
When vulcanizing 11 as it is with a vulcanizing mold, the rubber flow during vulcanization becomes uneven, so the vulcanized tire has an uneven tread gauge, air enters the tread rubber,
There is a problem that tires such as durability and appearance are deteriorated due to generation of bears and the like.

[0005] In order to suppress such deformation, as shown in Fig. 8, there has been proposed a device provided with a support 15 for supporting the unvulcanized tire 11 from below when the unvulcanized tire 11 is conveyed. However, immediately before the unvulcanized tire 11 is carried into the vulcanization mold, the transportation is temporarily interrupted and the support 15 is largely moved radially outward to remove the unvulcanized tire 11 from below the unvulcanized tire 11. Since it must be output, there is a problem that the working efficiency is reduced.

An object of the present invention is to provide a large tire for a construction vehicle capable of producing a high-quality tire with high efficiency and a method for producing the same.

[0007]

SUMMARY OF THE INVENTION The purpose of the invention is as follows.
A large tire for a construction vehicle, comprising: a pair of beads; a pair of sidewalls each extending substantially radially outward from the beads; and a substantially cylindrical tread connecting the sidewalls. In, a large tire for a construction vehicle configured by leaving at least a part of the circumferential groove into which the conveying claw is inserted, formed near the tread center of the tread portion when the unvulcanized tire is left until after vulcanization,

[0008] Second, a step of forming a circumferential groove near the tread center on the outer surface of the tread portion of the unvulcanized tire;
A step of transporting the unvulcanized tire to the vulcanizing mold while inserting the transporting claw in the circumferential groove while gripping the unvulcanized tire at the tread portion; A large tire for a construction vehicle, comprising: a step of extracting a claw from a circumferential groove; and a step of vulcanizing the unvulcanized tire with a vulcanizing mold and leaving at least a part of the circumferential groove until after vulcanization. Can be achieved.

When manufacturing the tire as described above,
First, a circumferential groove is formed near the tread center on the outer surface of the tread portion of the unvulcanized tire, and then a transport claw is inserted into the circumferential groove. Hold. In this state, the transport claws are moved, and the unvulcanized tire is transported to the vulcanizing mold.At this time, since the heavy tread portion is gripped by the transport claws, the load applied to the sidewall portion is small. Become
As a result, the sagging deformation of the sidewall portion during transport of the unvulcanized tire is effectively suppressed. When the deformation is reduced in this way, the rubber flow during vulcanization becomes uniform, and the durability, appearance, etc. of the vulcanized tire are improved,
Tire quality is improved.

Next, the unvulcanized tire is carried into a vulcanizing mold, and the transport claws are pulled out from the circumferential groove. The transport claws extend radially outward for a distance slightly longer than the depth of the circumferential groove. Since it is possible to extract from the circumferential groove only by moving, the extraction operation is quick and easy, and as a result, the operation efficiency is improved. Next, the unvulcanized tire is vulcanized by a vulcanizing mold, and at least a part of the circumferential groove is left until after vulcanization.

[0011] Further, according to the third aspect of the present invention, when inserting the conveying claw into the circumferential groove of the unvulcanized tire,
Since there is no need to align the circumferential position of the conveying claw with the circumferential groove, the work is facilitated. Further, according to the structure as described in claim 4, since the reduction in the amount of rubber in the vicinity of the tread center can be suppressed, the wear durability is improved.

Further, according to the structure of the fifth aspect, the deformation of the unvulcanized tire, particularly, the sidewall portion during the transportation can be strongly suppressed. Further, according to the structure described in claim 6, it is possible to suppress a situation in which a bear is generated in the vicinity of the circumferential groove due to an insufficient amount of the flowing rubber during vulcanization. Further, according to the structure described in claim 7, it is possible to effectively suppress the occurrence of bears while preventing a decrease in tire quality.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 21 denotes a vulcanized large radial tire (product tire) to be mounted on a construction vehicle. The tire 21 includes a pair of bead portions 23 in which bead cores 22 are respectively buried, and a plurality of bead portions 23. The vehicle includes a pair of sidewall portions 24 extending outward in the radial direction, and a substantially cylindrical tread portion 25 connecting the radially outer ends of the sidewall portions 24 to each other.

The tire 21 is mounted on the bead core 22.
It has a carcass layer 28 extending substantially toroidally between the side walls 24 and the tread portion 25, and the carcass layer 28 is moored to the bead core 22 by folding both ends around the bead core 22. ing. A large number of non-extensible cords extending substantially in the radial direction (meridian direction) are embedded in the carcass layer 23.

Reference numeral 31 denotes a plurality of belt layers disposed radially outside the carcass layer 28. Inside each belt layer 31, a number of non-extensible cords parallel to each other are embedded.
Here, the cords embedded in the belt layer 31 incline in the range of 10 degrees to 40 degrees with respect to the tread center S, and incline in the opposite direction at least in the two adjacent belt layers 31 to intersect each other. are doing.

In FIGS. 1 and 2, reference numeral 33 denotes a tread disposed radially outside the belt layer 31. On the outer surface of the tread 33, a number of treads extending from both tread ends 34 toward the tread center S are provided. A lug groove 35 is formed. These lug grooves 35 are inclined at a predetermined angle with respect to the tread center S, and are arranged at equal distances in the circumferential direction. Also, this tread 33 (tread part
On the outer surface of 25), a center groove 36 is formed in the vicinity of the tread center S, here on the tread center S. is there. In addition, this center groove 36
As shown in FIG. 3, it may be bent zigzag in the tire width direction.

Next, in order to manufacture the vulcanized tire 21 as described above, first, an unvulcanized tire 41 is formed using a tire forming drum (not shown). At this time, as shown in FIG. 4, a circumferential groove 42 is formed near the tread center S on the outer surface of the tread portion 25 of the unvulcanized tire 41, here, on the tread center S. Is an annular groove extending continuously in the circumferential direction over the entire circumference of the tread portion 25.

Here, the depth of the circumferential groove 42 is
Is preferably in the range of 25 to 50% of the rubber gauge at the installation position. The reason is that if it is less than 25%, the transport claws inserted into the circumferential groove 42 during the later-described transport may come off, whereas if it exceeds 50%, the circumferential groove 42
This is because the rubber gauge on the bottom wall becomes thinner, and the wear life and cut penetration resistance of the vulcanized tire 21 may be reduced. The width of the circumferential groove 42 is preferably in the range of 4% to 12% of the tread width of the unvulcanized tire 41. The reason is that if it is less than 4%, the circumferential groove will be
This is because the transport claws inserted into 42 may come off, while if it exceeds 12%, the center groove 36 which is too wide remains in the tread portion 25 of the vulcanized tire 21. It is because.

Next, when the unvulcanized tire 41 is detached from the tire building drum and mounted on the shaping mechanism 43, the unvulcanized tire 41 is gripped by the shaping mechanism 43 from the inside in the radial direction. Here, the shaping mechanism 43 includes a first molded piece 44 on which one bead 23 of the unvulcanized tire 41 is seated, a second molded piece 45 on which the other bead 23 is seated, One molded piece 44 has the other end
A bendable bladder 46 is attached to the molded piece 45 in an airtight state.

Then, one bead portion 23 is attached to the first molding piece 44.
After the other bead portion 23 is seated on the second molded piece 45 and the first and second molded pieces 44 and 45 are connected to each other, the unvulcanized tire 41 is mounted on the shaping mechanism 43, When the bladder 46 is filled with internal pressure, the unvulcanized tire
The outer shape of 41 is approximated to the inner surface shape (shape of the molding surface) of a vulcanizing mold described later. Thereby, the flow of rubber during vulcanization becomes smooth, and poor vulcanization is effectively suppressed.

At this time, the unvulcanized tire 41 mounted on the shaping mechanism 43 is placed in a horizontal state (horizontal state), and the conveying claw 57 of the conveying device 50 is moved to the unvulcanized tire.
The unvulcanized tire 41 is held in the tread portion 25 from the outside in the radial direction by the transport device 50 in the tread portion 25. Here, as described above, the circumferential groove 42 is
Since the annular groove continuously extends in the circumferential direction over the entire circumference of the peripheral groove, when the transport claw 57 is inserted into the circumferential groove 42, the circumferential alignment of the transport claw 57 and the circumferential groove 42 is performed. It is not necessary to perform the operation, and as a result, the work becomes easy.

Here, the transfer device 50 has a horizontal base plate 51, an upper end connected to the center of the lower surface of the base plate 51, and a lower end formed by a first molded piece 44 of the shaping mechanism 43.
And a plurality of suspending members 52 that can be connected to the vehicle. Reference numeral 53 denotes a plurality of radially extending rails laid on the outer edge of the lower surface of the base plate 51, and these rails 53 are arranged at equal distances in the circumferential direction. Reference numeral 54 denotes a plurality of movable bases to which slide bearings 55 slidably engaged with the respective rails 53 are attached, and the lower surface of these movable bases 54 is connected to an upper end of a connecting body 56 extending vertically. At the lower end of each connecting body 56, a horizontal arc-shaped conveying claw 57 is attached.

Numeral 58 denotes a plurality of radially extending cylinders mounted on the lower surface of the base plate 51 radially inward of the movable base 54.
The tip of 59 is connected to the movable base 54. As a result,
When the cylinder 58 is operated synchronously and the piston rod 59 is retracted, the transport claw 57 is moved inward in the radial direction synchronously, and the radially inner portion is inserted into the circumferential groove 42. In this manner, the unvulcanized tire 41 is gripped from the radial outside by the transport claw 57 of the transport device 50 in the tread portion 25.

Here, the distance from the upper surface of the conveying claw 57 to the lower surface of the base plate 51 is determined by the shape-shaped (undeformed) unvulcanized tire mounted on the shaping mechanism 43.
The lower surface of the base plate 51 and the circumferential groove when 41 is suspended from the base plate 51 by the suspending member 52
It is almost equal to the distance between the upper side wall of 42. As a result, when the base plate 51 is lifted, the unvulcanized tire 41
Is suspended from the base plate 51 while being held by the shaping mechanism 43 and the transfer claws 57 while substantially maintaining the shaping shape.

It is preferable that the circumferential length of each transport claw 57 is not less than 1/18 of the outer peripheral length of the tread portion of the unvulcanized tire 41. The reason is that if the outer peripheral length of the tread portion 25 is less than 1/18, the contact pressure between the circumferential groove 42 and the transport claw 57 during the transport becomes too high when the number of the transport claws 57 is two. This is because the circumferential groove 42 may be deformed. The hanging member 52, the movable base 54, the connecting body 56, and the transport claws 5 described above.
7. The cylinder 58 constitutes the transfer device 50 as a whole.

A shaping mechanism 43 gripping the unvulcanized tire 41 from the inside in the radial direction is connected to the lower end of the suspending member 52. When the pawl 57 is inserted and the unvulcanized tire 41 is gripped from the radial outside by the transport pawl 57, the base plate 51 is lifted by a crane (not shown),
To the vulcanizing mold 61 shown in FIG. At this time, since the heavy tread portion 25 was gripped by the transport claws 57 as described above, the load applied to the sidewall portion 24 was reduced, and as a result, the sidewall portion during transport of the unvulcanized tire 41 was reduced. 24 drooping deformation is effectively suppressed.
In addition, since the unvulcanized tire 41 is also gripped by the shaping mechanism 43 from the inside in the radial direction during such transportation, the deformation of the sidewall portion 24 of the unvulcanized tire 41 is strongly suppressed.

Here, the vulcanization mold 61 is separated from the lower mold 62 which is left standing, and the lower mold 62 by moving up and down.
An upper mold 63 that is accessible, and when the upper mold 63 approaches the lower mold 62 and is closed, the unvulcanized tire 41 is stored in the lower and upper molds 62 and 63. A space is formed. In addition, these lower and upper molds 62 and 63
Of the uncured tire 41 is a molding surface 64 that defines the outer surface shape of the unvulcanized tire 41, and a large number of lug bones 65 complementary to the lug groove 35 are formed at the region where the tread portion 25 of the molding surface 64 is molded. Is formed.

When the unvulcanized tire 41 is vulcanized by using such a vulcanized mold 61, the unvulcanized tire 41 is placed on the lower mold 62 of the open vulcanized mold 61. After being loaded and loaded by the transfer device 50, the piston rod 59 of the cylinder 58
Are synchronously moved outward in the radial direction, and are withdrawn from the circumferential groove 42. At this time, the carrier claw 57 can be extracted from the circumferential groove 42 only by moving it outward in the radial direction by a distance slightly longer than the depth of the circumferential groove 42, so that the extracting operation is quick and simple, and as a result, Work efficiency is improved.

Next, while the transfer device 50 is returned to the initial position, the upper mold 63 is brought close to the lower mold 62 to close the lower and upper molds 62, 63.
The unvulcanized tire 41 is vulcanized by 61 and the vulcanized tire 21
And At this time, if the deformation of the unvulcanized tire 41 during transportation is small as described above, the rubber flow during vulcanization becomes uniform, and the durability, appearance, etc. of the vulcanized tire 21 are improved, and the tire quality is improved. I do. In addition, during this vulcanization, the rubber flows into the circumferential groove 42, thereby
Is at least partially closed.

Here, if the entire circumferential groove 42 is to be closed with rubber, the amount of flowing rubber may be partially insufficient during vulcanization, and in such a case, a bear is provided near the circumferential groove 42. It is easy to occur. For this reason, in this embodiment, at a position facing the circumferential groove 42 of the molding surface 64 for molding the tread portion 25, a cross section smaller than the cross section of the circumferential groove 42 is formed over the entire circumference of the molding surface 64. A circumferential ridge 66 extending continuously in the direction is formed.

When the unvulcanized tire 41 is vulcanized by the vulcanization mold 61, the circumferential ridge 66 is used to cure the unvulcanized tire 41.
41 is inserted into the circumferential groove 42, the circumferential groove 42 is partially closed by the rubber flow by vulcanization, and the remaining part whose cross section has the same shape as the circumferential ridge 66 is the tread center S. The above-mentioned center groove 36 remains in the vicinity until after vulcanization. When the circumferential ridge 66 is provided on the molding surface 64 in this manner, the amount of rubber flowing into the circumferential groove 42 is reduced, and thus the occurrence of the above-described bear is suppressed.

Here, the width of the circumferential ridge 66 (groove width L of the center groove 36) is 3 to 10% of the tread width W, and the amount of protrusion (groove depth M of the center groove 36) is determined by the tread portion 25. The lug groove 35 preferably has a depth G in the range of 20 to 40%. The reason for this is that if the width is less than 3% of the tread width W or less than 20% of the depth G, the amount of rubber flowing into the circumferential groove 42 may increase, and a bear may be generated.
On the other hand, if it exceeds 10% of the tread width W or exceeds 40% of the depth G, the rubber gauge at the groove bottom of the center groove 36 becomes too thin, and the wear life and cut penetration resistance decrease. This is because there is a fear.

FIG. 6 is a diagram showing a second embodiment of the present invention. In this embodiment, two or more center grooves 70 formed of arc-shaped grooves are arranged on the tread portion 25 of the vulcanized tire 21 at equal intervals in the circumferential direction. In this case, a similar circumferential groove is provided intermittently in the circumferential direction in the tread portion 25 of the unvulcanized tire 41. And if you do this,
A reduction in the amount of rubber in the vicinity of the tread center S can be suppressed, thereby improving wear durability. Here, the above-mentioned center groove 70 (circumferential groove)
Is preferably not less than 1/18 of the outer peripheral length of the unvulcanized tire 41 in the tread portion 25. The reason is,
If it is less than 1/18, when there are two circumferential grooves, the contact pressure between the circumferential grooves and the transport claws during transport may become too high and the circumferential grooves may be deformed. is there.

In the above-described embodiment, since the shaping mechanism 43 is of a type that can be separated from the vulcanization mold 61, the unvulcanized tire 41 is transported when the unvulcanized tire 41 is transported. Although the shaping mechanism 43 is also used to grip the inside of the vulcanizing mold from the radially inner side. You only need to hold it.

In the above-described embodiment, a part of the circumferential groove 42 is left as the center groove 36 after vulcanization by partially closing the circumferential groove 42 by vulcanization. In the present invention, the entire circumferential groove may be left as it is as a wide groove until vulcanization without closing the circumferential groove by vulcanization, or the circumferential groove may be expanded by vulcanization to form a circumferential groove. The whole may be left as a part of the wide groove until after vulcanization.

[0036]

Next, test examples will be described. In this test, the working tire 1 having a tire size of 40.00 R57, the working tire 2 having a tire size of 37.00 R57, and 5
A working tire 3 of 5.5 / 80-57 was prepared. here,
The circumferential groove at the time of unvulcanized tire of each of these tires,
Groove width is 55mm, 30mm, 116mm respectively, groove depth is each
27mm, 25mm, 44mm, the groove lengths are all around (continuous), all around (continuous), 540mm x 10 pieces, and the lug grooves for vulcanized tires are 960mm, 845mm,
1220mm, depths are 91.5mm, 87.5mm, 121.5mm respectively, and the center groove when vulcanized tire is
Each width is 45mm, 25mm, 95mm, depth is 22mm,
The groove length was 20 mm, 36 mm, the entire circumference (continuous), the entire circumference (continuous), and 540 mm × 10.

Next, each unvulcanized tire as described above is conveyed to a vulcanization mold while being gripped from the inside and outside in the radial direction using a shaping mechanism and a conveying claw, and then the vulcanization mold is removed. To obtain a vulcanized tire. Here, during the above-described transport, the transport claws did not come off the circumferential grooves, and the appearance inspection was performed on each of the vulcanized tires. There was no air in the air and no bears were generated.

[0038]

As described above, according to the present invention, a high-quality tire can be manufactured with high efficiency.

[Brief description of the drawings]

FIG. 1 is a meridional section of a vulcanized tire according to a first embodiment of the present invention.

FIG. 2 is a plan view of a tread portion of the tire shown in FIG.

FIG. 3 is a plan view of a tread portion showing another embodiment of the present invention.

FIG. 4 is a partially cutaway front view illustrating a transport state of an unvulcanized tire.

FIG. 5 is a partially broken front view illustrating a vulcanized state of an unvulcanized tire.

FIG. 6 is a plan view of a tread portion showing a second embodiment of the present invention.

FIG. 7 is a partially broken front view illustrating a state of transporting a conventional unvulcanized tire.

FIG. 8 is a partially cutaway front view illustrating another conveyance state of a conventional unvulcanized tire.

[Explanation of symbols]

 21… Large tire for construction vehicles 23… Bead part 24… Side wall part 25… Tread part 36… Center groove 41… Uncured tire 42… Circumferential groove 43… Shaping mechanism 57… Transport claw 61… Vulcanization mold 64: Molding surface 66: Circumferential ridge S: Tread center

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 105: 24 B29L 30:00

Claims (7)

[Claims] 1. A construction vehicle comprising: a pair of beads; a pair of sidewalls each extending substantially radially outward from the beads; and a substantially cylindrical tread connecting the sidewalls. For large tires, formed at the vicinity of the tread center of the tread portion at the time of unvulcanized tire, at least a part of the circumferential groove into which the conveying claw is inserted, characterized by leaving until after vulcanization Large tires for construction vehicles. 2. A step of forming a circumferential groove near the tread center on the outer surface of the tread portion of the unvulcanized tire, and inserting a transport claw into the circumferential groove to move the unvulcanized tire in the tread portion. A step of transporting the unvulcanized tire to the vulcanization mold while gripping, and a step of extracting the transport claws from the circumferential groove while carrying the unvulcanized tire into the vulcanization mold; and Vulcanizing and leaving at least a part of the circumferential groove until after vulcanization. 3. The method for manufacturing a large tire for a construction vehicle according to claim 2, wherein the circumferential groove is an annular groove extending continuously in the circumferential direction over the entire circumference of the tread portion. 4. The circumferential groove according to claim 2, wherein the circumferential groove is an arc-shaped groove having a circumferential length equal to or more than 1/18 of the outer peripheral length of the tread portion, and two or more arc-shaped grooves are arranged at equal intervals in the circumferential direction. Manufacturing method of large tires for construction vehicles. 5. When a transport claw is inserted into the circumferential groove and the unvulcanized tire is gripped at the tread portion, the bead portion of the unvulcanized tire is gripped from the radial inside by a shaping mechanism. The method for producing a large tire for a construction vehicle according to claim 2, wherein the unvulcanized tire is gripped from inside and outside. 6. A circumferential projection having a cross section smaller than a circumferential groove formed in an unvulcanized tire is formed on a molding surface for molding a tread portion of the vulcanized mold. 3. A vulcanizing mold for vulcanizing, wherein a circumferential ridge is inserted into a circumferential groove of the unvulcanized tire, and a part of the circumferential groove is closed by rubber flow by vulcanization. A method for producing a large tire for a construction vehicle according to the above. 7. A center groove is formed near a tread center of a vulcanized tire by closing a part of a circumferential groove by the rubber flow, and a groove width L of the center groove is set to 3 to 10 of a tread width W. The manufacturing method of a large tire for a construction vehicle according to claim 6, wherein the groove depth M is within a range of 20 to 40% of the lug groove depth G in the tread portion.