JPH0524561Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a lug tire, particularly a lug tire mounted on agricultural machinery.

Conventional technology Conventionally, in order to increase the traction force when used on soft soil, lug tires installed on agricultural machinery are arranged in multiple pieces on the circumferential surface of the crown part at equal distances apart in the circumferential direction. It has lugs with high radial height. In such tires with lugs for agricultural machinery, the height of the lugs and the spacing (distance) between two circumferentially adjacent lugs are the same as the tread of tires of similar lug type, such as tires for trucks and buses. The lug height and lug spacing are typically significantly higher and wider than the lug heights and lug spacings in In addition, when manufacturing such tires with lugs for agricultural machinery, an unvulcanized tire is inserted into a mold having deep lug recesses on the inner surface, and the radially inner surface of the unvulcanized tire is passed through a bladder. It is customary to vulcanize the tire by heating the outer surface of the mold and the inner surface in the radial direction of the unvulcanized tire while applying steam pressure. During vulcanization, the unvulcanized tire is heated and pressurized, so the viscosity of the rubber decreases and the rubber flows along the unevenness formed on the inner surface of the mold, forming a lag. Ru.

Problems that the invention aims to solve: Although the flow of rubber to the lugs is easy near the lugs, there are various restrictions in areas away from the lugs, that is, near the middle of two adjacent lugs. It is often incomplete. In such a case, the gauge thickness of the rubber in the groove near the proximal end of the lug will be as specified, but the thickness of the two adjacent
In the grooves near the middle of the two lugs, rubber left behind in the flow remains and the gauge thickness becomes thick, resulting in a problem that the gauge thickness in the grooves becomes non-uniform. Since the height of the lug from the groove bottom is greatest at the shoulder portion, such non-uniformity in gauge thickness is most noticeable at the groove portion connected to the proximal end (root) of the shoulder portion. Here, since the bottom surface of the groove is in surface contact with the mold during vulcanization, the bottom surface of the groove is almost flat. It appears uneven. When the gauge thickness becomes non-uniform as described above, there is a problem that the intervals between the cords embedded in the carcass layer and the breaker layer reinforcing the tire are disturbed. Moreover, when a tire with uneven gauge thickness as mentioned above is filled with internal pressure, the inner surface of the tire in the radial direction becomes almost flat due to the influence of the internal pressure. A convex portion is formed so as to protrude outward in the radial direction. Here, since high tension is generated on the surface of such convex parts, even if a slight scratch is caused, the scratch easily progresses toward the inside, resulting in a problem in that the cut resistance performance decreases. be.

This invention prevents unevenness that occurs on the inner surface of the tire in the radial direction during vulcanization, reduces irregularities in the spacing between the cords embedded in the carcass layer and breaker layer, and also provides protection against external damage such as cut resistance. The purpose is to provide a tire with lugs for agricultural machinery that can also improve performance.

Means for Solving the Problem This purpose is to maintain a large number of lugs 8 extending from the tire equator 5 toward both shoulders on the circumferential surface of the crown portion at wide intervals in the circumferential direction on both sides of the tire equator 5. By protruding in rows while keeping the distance between the two lugs 8,
In a lug-equipped tire 1 for agricultural machinery in which grooves 9 extending along the lugs 8 are formed in between, a protrusion 10 is provided in the groove 9 between two circumferentially adjacent lugs 8 at a distance from both lugs 8. established,
The height of each protrusion 10 from the groove bottom is maximized at the shoulder portion 10c located on the radially inner side of the shoulder portion 4 where the height of the lug 8 is actually the highest in the radial cross section of the tire 1. , extend from the shoulder portion 10c toward the tire equator 5 and the side portion 11 while gradually decreasing the height from the groove bottom, and the radial outer surface 10b of these projections 10 is connected to the radial outer surface 8a of the lug 8. At the same time, the axial outer surface 10a of the protrusion 10 is positioned closer to the tire equator 5 than the axial outer surface of the lug 8, and the height of the shoulder portion 10c of these protrusions 10 from the groove bottom is set to the lugs 8. This can be achieved by making the height lower than the height from the groove bottom of the shoulder portion 4 of No.8.

Effect Suppose that an unvulcanized tire is being vulcanized. At this time, the rubber flows easily toward the lug 8 near the proximal end of the lug 8;
In a region far from the proximal end of the lugs 8, that is, near the middle of two adjacent lugs 8, the lugs 8 are often incomplete due to various restrictions. In such a case, the gauge thickness of the rubber in the groove 9 near the base end of the lug 8 will be as specified, but the rubber left behind in the flow will remain in the groove 9 near the middle of two adjacent lugs 8. Therefore, the gauge thickness becomes thicker. Therefore, in this invention, the rubber remaining in the vicinity of the middle of these lugs 8 is actively collected on the outer surface side, and the groove 9 in the middle of two circumferentially adjacent lugs 8 is spaced apart from both lugs 8. The protrusion 10 is provided to maintain the same position. As a result, during vulcanization, the intermediate portions of the two lugs 8 hardly protrude inward in the radial direction to form convex portions, and are almost flat. Therefore, disturbances in the intervals between the cords embedded in the carcass layer 2 and the breaker layer 6 can be reduced, and protection against external damage such as cut resistance can also be improved. As mentioned above, the flow of rubber during vulcanization is maximum at the shoulder section 4 of the lug 8, which is actually the highest in height from the groove bottom. The remaining amount will also be maximum. Therefore, the protrusion 10 located on the radially inner side of the shoulder portion 4 of the lug 8 is the shoulder portion 10c, and the shoulder portion 1 of the protrusion 10 is
The height from the groove bottom at 0c is the largest among the protrusions 10, and the height of the protrusions 10 gradually decreases from the shoulder portion 10c toward the tire equator 5 and side portions 11. Here, as mentioned above, since the protrusion 10 is formed by collecting excess rubber, it is smaller than the lug 8. Therefore, the height of the shoulder portion 10c from the groove bottom of the shoulder portion 4 of the lug 8 is The radial outer surface 10b of the protrusion 10 is located radially inner than the radial outer surface 8a of the lug 8, and the axial outer surface 10a thereof is lower than the axial outer surface of the lug 8. It is located on the equator 5 side.

Furthermore, if configured as in claim 2,
The gauge thickness can be reliably made uniform without reducing the deflection of the lug 8.

Embodiment Hereinafter, an embodiment of this invention will be described based on the drawings.

In Figs. 1 and 4, reference numeral 1 denotes a lug tire to be mounted on an agricultural machine, and this tire 1 has at least one carcass layer 2 on the innermost side in the radial direction. 3, passes through the shoulder portion 4 and reaches the tire equator 5.
Furthermore, the tire 1 has at least one breaker layer 6 for reinforcing the carcass layer 2 in the radially outer crown portion of the carcass layer 2, and this breaker layer 6
Both ends in the width direction reach the shoulder portion 4. Here, both the carcass layer 2 and the breaker layer 6 are composed of plies in which cords made of metal or fiber are covered with a coating rubber. Each cord of the carcass layer 2 is arranged at a predetermined angle with respect to the tire equator 5, and if there is another carcass layer overlapping this carcass layer 2, the cords of the other carcass layer are arranged at a predetermined angle with respect to the tire equator 5. It is arranged so that it intersects the code of 2. Note that the carcass layer 2 is not limited to the above, and the cords may be arranged substantially perpendicularly to the tire equator 5 of the tire 1. On the other hand, breaker layer 6
Each cord is arranged at a predetermined angle with respect to the tire equator 5 of the tire 1, and if there is another breaker layer overlapping this breaker layer 6, the cords of the other breaker layer are arranged at a predetermined angle with respect to the tire equator 5 of the tire 1. Arranged to intersect the code.

A tread rubber layer 7 is disposed on the radially outer crown portions of the carcass layer 2 and the breaker layer 6, and on the circumferential surface of the tread rubber layer 7, there are a number of protruding lugs 8 of approximately equal width. They are arranged in a known arrangement. That is, these lugs 8 extend from the tire equator 5 toward the shoulder portions 4 on one side and the other side, and are protruded in rows on both sides of the tire equator 5 while maintaining wide intervals in the circumferential direction. It is. The lugs 8 placed on one side of the tire equator 5 and the lugs 8 placed on the other side are mutually spaced from each other in the circumferential direction by a distance between two circumferentially adjacent lugs 8, that is, 1/2 of the pitch. It is shifted. Further, these lugs 8 are inclined toward the front in the rotational direction of the tire 1 as they approach the tire equator 5 from the shoulder portion 4, and have a generally arcuate planar shape. As a result, a large number of grooves 9 extending along the lugs 8 are formed on the circumferential surface of the tread rubber layer 7, and each groove 9 is formed between two circumferentially adjacent lugs 8.
placed in between.

As shown in FIGS. 1, 3, and 4, the grooves 9 in the middle of two circumferentially adjacent lugs 8 each have a
A protrusion 10 having a substantially equal width is provided at a predetermined distance from both lugs 8, that is, leaving a narrow groove between the two lugs 8. Each protrusion 10 has a maximum height from the bottom of the groove 9 in the shoulder portion 10c;
0c is located on the radially inner side of the shoulder portion 4 where the height of the groove portion 9 from the groove bottom is actually the maximum in the radial cross section of the tire 1. The height of the protrusion 10 from the groove bottom in the shoulder portion 10c is lower than the height of the lug 8 from the groove bottom in the shoulder portion 4, for example, about 0.05 to 0.30 times the height of the lug 8 in the shoulder portion 4. be. Moreover, each protrusion 10 has this maximum height shoulder portion 1
The grooves 9 extend from the shoulder portion 10c toward the tire equator 5 and the side portion 11 of the tire 1.
It gradually decreases as it approaches 1. Here, the end of each protrusion 10 on the side portion 11 side is aligned with the end of the lug 8 on the side portion 11 side in order to facilitate the production of the vulcanization mold. Note that the groove bottom of the groove portion 9 is indicated by a dotted line KK in FIG. Further, the radially outer surface 10b of each protrusion 10 is located radially inward than the radially outer surface 8a of the lug 8, and
The axially outer surface 10a of each protrusion 10 is located axially inner than the axially outer surface of the lug 8, that is, on the tire equator 5 side. In this embodiment, the radially outer surface 10b of each protrusion 10 in the radial cross section of the tire 1 extends substantially parallel to the radially outer surface 8a of the lug 8, while the radially outer surface 10b of each projection 10 in the radial cross section of the tire 1 The axially outer surface 10a of the projection 10 also extends substantially parallel to the axially outer surface of the lug 8. Further, the planar shape of the protrusion 10 is, for example, approximately arc-shaped, as shown in FIG. 4, and the center line of the protrusion 10 extending in the longitudinal direction is substantially parallel to the center line extending in the longitudinal direction of the lug 8. Further, the circumferential minimum width W1 of the radial outer surface 10b of the protrusion 10 is as follows:
It is preferably in the range of 0.3 to 0.7 times the maximum width W2 of the groove portion 9 located between the shoulder portions 4 of the two lugs 8 adjacent to the protrusion 10, and more preferably in the range of 0.45 to 0.55 times. The reason is,
If it is less than 0.3 times, the circumferential width of the protrusion 10 will become too narrow, and the effect of collecting residual rubber during vulcanization will be reduced, resulting in uneven gauge thickness. On the other hand, if it is more than 0.7 times, , lug 8 and protrusion 10
This is because the width of the groove remaining between the two tires becomes too narrow, which reduces the deflection of the lugs 8 during running and reduces the traction force of the tire 1. For this reason, the total area of the protrusion 10 is generally the total area of the lug 8.
The range is from 0.01 to 0.09 times.

Next, a case will be described in which the tire 1 as described above is vulcanized, and such a vulcanization method is a conventionally well-known and usual method. That is, first, the second
As shown in the figure, after an unvulcanized tire is inserted into a mold 12, the radial inner surface of the unvulcanized tire is pressurized by steam pressure through a bladder, and the mold 12 is
The outer surface of No. 2 and the radially inner surface of the unvulcanized tire are heated and vulcanized. During such vulcanization, the unvulcanized tire is heated and pressurized, so the viscosity of the rubber decreases and a flow lag 8 is formed along the unevenness formed on the inner surface of the mold 12. Ru. Although the flow of rubber to the lug 8 is easy near the proximal end of the lug 8, it is often incomplete near the middle of two adjacent lugs 8 due to various restrictions. . In such a case, the gauge thickness of the rubber in the groove 9 near the base end of the lug 8 will be as specified, but the rubber left behind in the flow will remain in the groove 9 near the middle of two adjacent lugs 8. As a result, the gauge thickness becomes thicker, and the gauge thickness at the groove portion 9 becomes non-uniform. For this reason, in this embodiment, the rubber remaining near the middle of these lugs 8 is actively collected on the outer surface side, and the rubber remaining in the vicinity of the middle of these lugs 8 is collected in a groove 9 between two circumferentially adjacent lugs 8 at a distance from both lugs 8. The protrusion 10 is provided while maintaining the same. As a result, during vulcanization, the intermediate portions of the two lugs 8 hardly protrude inward in the radial direction to form convex portions, and are almost flat.
Therefore, disturbances in the intervals between the cords embedded in the carcass layer 2 and the breaker layer 6 can be reduced. Furthermore, even when such a tire 1 is filled with internal pressure, since the inner surface in the radial direction of the tire 1 is almost flat during vulcanization, the vicinity of the middle of the two lugs 8 does not protrude outward in the radial direction. As a result, cut resistance performance is also improved. The flow of rubber during vulcanization is determined by the shoulder portion 4 of the lug 8, which has the highest height from the groove bottom, as described above.
Since the amount of rubber remaining in the groove portion 9 on the inside of the shoulder portion 4 in the radial direction is maximum, the amount of rubber remaining is also maximum. Therefore, the protrusion 10 located on the radially inner side of the shoulder portion 4 of the lug 8 is the shoulder portion 10c, and the height of the shoulder portion 10c of the protrusion 10 from the groove bottom is the largest among the protrusions 10. At the same time, the height of the protrusion 10 is gradually decreased from the shoulder portion 10c toward the tire equator 5 and the side portion 11.
Here, as mentioned above, the protrusion 10 is formed by collecting excess rubber, so it is smaller than the lug 8.
Therefore, the height of the shoulder portion 10c from the groove bottom is lower than the height of the shoulder portion 4 of the lug 8 from the groove bottom, and the radial outer surface 10b of the projection 10 is lower than the height of the shoulder portion 4 of the lug 8 from the groove bottom.
is located radially inward from the radially outer surface 8a of the lug 8, and its axially outer surface 10a is located closer to the tire equator 5 than the axially outer surface of the lug 8. In addition, the lug 8 of such tire 1
is two lugs 8 with protrusions 10 adjacent to each other in the circumferential direction.
Since they are arranged at a distance from each other, when a large tractive force is applied, they can be largely deflected in the circumferential direction, and there is no possibility of insufficient deflection. Furthermore, even if mud is caught between two adjacent lugs 8, the mud will easily fall off due to the large deflection of the lugs 8, and the mud removal performance will not be degraded.

Effects of the invention As explained above, according to this invention, it is possible to prevent irregularities that occur on the radial inner surface of the tire during vulcanization, and also to reduce irregularities in the intervals between the cords embedded in the carcass layer and the breaker layer. In addition, it is possible to improve protection against external damage such as cut resistance.

[Brief explanation of the drawing]

Figure 1 shows an example of this invention.
-J arrow sectional view, Figure 2 is a cross-sectional view of the mold and unvulcanized tire to explain the rubber flow when vulcanizing an unvulcanized tire, and Figure 3 is an enlarged A-A of Figure 1. cross section,
FIG. 4 is a developed view of the vicinity of the crown portion of the embodiment. 1... Tire with lug for agricultural machinery, 4... Shoulder part, 5... Tire equator, 8... Lug, 9...
...Groove portion, 10...Protrusion, 10a...Axially outer surface, 10b...Radially outer surface, 10c...Shoulder portion, 11...Side portion.

Claims (1)

[Claims for Utility Model Registration] (1) A large number of lugs 8 extending from the tire equator 5 toward both shoulders on the circumferential surface of the crown portion are provided on both sides of the tire equator 5 while maintaining wide intervals in the circumferential direction. In a lug tire 1 for agricultural machinery in which grooves 9 extending along the lugs 8 are formed between two circumferentially adjacent lugs 8 by protruding in rows, two circumferentially adjacent lugs 8 are provided. A protrusion 10 is provided in the groove 9 between the two lugs 8 at a distance from both lugs 8,
Each protrusion 10 is connected to a shoulder portion 4 where the height of the lug 8 is actually the highest in the radial cross section of the tire 1.
Shoulder portion 10c located on the radially inner side of
The height from the groove bottom is maximized at the tire equator 5 from the shoulder portion 10c.
and extending toward the side portion 11 while gradually decreasing the height from the groove bottom, and positioning the radially outer surface 10b of these protrusions 10 radially inward than the radially outer surface 8a of the lug 8, Its axially outer surface 10a is located closer to the tire equator 5 than the axially outer surface of the lug 8, and the height of the shoulder portion 10c of these protrusions 10 from the groove bottom of the shoulder portion 4 of the lug 8 is adjusted from the groove bottom of the shoulder portion 4 of the lug 8. A tire with lugs for agricultural machinery, characterized in that the tire is lower than the height of the tire. (2) The minimum circumferential width W1 of the radially outer surface 10b of the protrusion 10 is within a range of 0.3 to 0.7 times the maximum width W2 of the groove 9 located between the shoulder portions 4 of the two lugs 8 adjacent to the protrusion 10. A tire with lugs for agricultural machinery according to claim 1 of the utility model registration claim.