JP3470288B2 - Pneumatic cushion tires for industrial vehicles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention improves the idling resistance without impairing the assembling property to the rim, and the partial wear of the tire bead portion caused by the tire bead portion coming into contact with the rim flange portion during traveling. In other words, the present invention relates to a pneumatic cushion tire for industrial vehicles, in which the basic performance around the bead portion is improved as a solid tire for a forklift that is commonly referred to as preventing rim displacement.

[0002]

2. Description of the Related Art Pneumatic cushion tires (hereinafter also simply referred to as tires) are solid tires for forklift trucks that have the same appearance as pneumatic tires. Especially, tires of this type are low speed, high load and stop. It is a type of tire that is often used under harsh conditions such as operating the steering wheel as it is.

Therefore, in this type of tire, due to the action of these high loads, slip and slip, that is, idling, easily occur between the tire and the rim, and at the same time, the tire vibrates vertically (e.g., in the radial direction) during running. Vibration), it also bends in the axial direction, and the bead part comes into contact with the rim flange part while moving back and forth in the circumferential direction, which is likely to cause partial wear of the bead part. The hardness of the base rubber of is increased, and in the base part,
It is common practice to incorporate bead wires.
The bead wire is tightened by the so-called tag effect,
The tire is strongly fitted to the rim R to prevent idling. Further, due to the reinforcement of the base portion, there is a problem that the assembling property with the rim deteriorates (it becomes difficult to assemble) and the load on the assembling press increases.

[0004]

However, in the tire having such a structure, the JIS-A hardness of the base rubber used for the base portion, the position of the bead wire in the base portion, and the tire base on the rim R are used. The basic characteristics of the tire relating to these four bead peripheral technologies, that is, the shape of the tightening margin around the bead part when assembled and the part that engages with the rim on the bottom of the base, must be balanced to the best degree. Of course, problems such as slipping and rim displacement may occur.

For the above-mentioned reasons, the present invention can eliminate the problems that have been apt to occur in conventional tires by balancing the technology around the base portion with the built-in position of the bead wire as the basic skeleton. It is an object of the present invention to provide a pneumatic type cushion tire for industrial vehicles.

[0006]

In order to solve the problems, the present invention takes the following means, that is, an industry comprising a tire base body in which a tread portion and a base portion or a tread portion, an intermediate layer portion and a base portion are integrated. In a pneumatic cushion tire for a vehicle, the base rubber has a JIS-A spring hardness (JIS-K6301) of 80 to 100 degrees, particularly preferably 85 to 95 degrees, and a tire including a tire shaft. A plurality of bead wires each having a value of the height BH of the base portion with respect to the tire height H in the meridional section, BH / H of 20 to 70%, particularly preferably 30 to 50%, and wound along the circumferential direction. In the base portion at a symmetrical position about the tire equator, and the inner diameter B of the bead wire is 102 to 10 of the rim large diameter RD to be used.
With an inner diameter of 7%, it is particularly desirable that the inner diameter be 103 to 105%,
Also, regarding the compression ratio of the rubber portion directly below the bead wire due to the rim assembly, the meridian of the tire including the tire axis when the rim is assembled with respect to the rubber thickness T immediately below the bead wire in the meridional section of the tire including the tire axis before the rim assembly. The ratio T ′ / T of the rubber thickness T ′ of the cross section is set in the range of 90 to 60%,
The tightening margin when assembling the rim of the tire base is rim width RW
The ratio (TW-RW) / RW of the value obtained by subtracting the rim width from the tire bead width is 3 to 15%, particularly preferably 5 to 12%. Ratio of the value obtained by subtracting the large bead diameter (RD-TD)
/ RD is -1 to 5%, particularly preferably 0 to 3%, and the ratio of the value obtained by subtracting the bead small diameter of the tire from the small rim diameter to the small rim diameter RSD (RSD-TSD) / RSD is 1 to 6%. And particularly preferably 2 to 4%.

When the number of bead wires is two, the ratio of the distance BW1 in the tire axial direction between the bead wires to the tire bead width TW, BW1 / TW, is 30 to 90%, and particularly preferably 40 to 70%,
When there are three or more bead wires, the tire bead width TW
To the rim flange, the ratio of the axial axial distance BW2 between the outer bead wires, BW2 / TW is 30 to
90%, particularly preferably 50 to 80%, and the total tensile strength of all the used bead wires is preferably 3000 to 30000 kgf.

In a meridional section including the tire shaft of the tire base body, a bead flat portion TFW is arranged on the bottom surface of the base portion at a symmetrical position about the tire equator and in parallel with the tire axis.
The ratio of the bead flat portion TFW to the rim flat portion RFW of the rim to be used, TFW / RFW is 0 to 1
It is preferably 50% and particularly preferably 80 to 120%.

In claim 1, JIS-A spring type hardness (JIS-K630) of the base rubber of the base portion.
By setting 1) to 80 to 100 degrees and setting the height BH of the base portion to the tire height H in the meridional section of the tire including the tire shaft to 20 to 70%, it is possible to mainly prevent rim displacement of the tire. .

The effect of preventing the rim displacement mainly depends on the increase in the longitudinal and lateral rigidity of the tire, and the increase in the hardness of the base rubber (same as JIS-A spring type hardness) is the same as the tire rigidity. Leads to a rise. When a considerably large lateral load is applied, the bead wire also contributes to ensuring lateral rigidity in the sense of fixing the base portion to the tire.

When the hardness of the base rubber is less than 80 degrees, the tire rigidity is reduced, the vertical vibration of the tire base portion and the axial and circumferential deflection / swing are increased, and thus the rim displacement is increased. The height B of the base portion with respect to the tire height H in the meridional section of the tire including the tire shaft
When the value of H and BH / H are smaller than 20%, the tire rigidity also becomes small, and similarly the tire flexure / swing becomes large and the rim displacement becomes large. On the other hand, if it exceeds 70%, the rubber layer of the tread portion which absorbs and absorbs impacts during running is relatively reduced, and various functions such as rolling resistance and heat generation suppression cannot be performed as the tread portion.

Further, according to the present invention, a plurality of bead wires wound along the circumferential direction are incorporated in the base portion at symmetrical positions with respect to the tire equator, and the inner diameter B of the bead wires is equal to the rim size to be used. The compression ratio of the rubber portion having an inner diameter of 102 to 107% of the diameter RD and directly below the bead wire by the rim assembly, with respect to the rubber thickness T immediately below the bead wire in the meridional section of the tire including the tire shaft before the rim assembly. Ratio of rubber thickness T'of the same cross section when assembled to rim T '/
T is set to 90 to 60%, that is, T is set to be compressed to a thickness of 90 to 60%, and idling is prevented by a so-called tag effect by tightening the bead wire.

When the inner diameter B of the bead wire is smaller than 102%, there is a risk that the bead wire comes too close to the rim and comes into contact with the bead wire. . Also, the work becomes difficult when the rim is assembled. On the other hand, if it exceeds 107%, the rubber thickness under the bead wire becomes too thick at the time of assembling the rim, and a sufficient tightening force cannot be obtained, resulting in idling.

Further, the ratio T '/ T of the rubber thickness T'of the same section at the time of rim assembly to the rubber thickness T just below the bead wire in the meridional section of the tire including the tire shaft before the rim assembly is 9.
If the value is larger than 0%, the compression rate of the rubber becomes small and the reaction force is lost, resulting in idling. When T '/ T becomes a value smaller than 60%, the compression ratio becomes too large this time, the hoop effect becomes too strong, and the workability of assembling the rim deteriorates, which is not preferable.

Therefore, the inner diameter B of the bead wire is set to 102 to 107% of the large diameter RD of the rim, and the same section at the time of the rim assembly with respect to the rubber thickness T just below the bead wire in the meridional section of the tire including the tire shaft before the rim assembly. Rubber thickness T '
The compression ratio T '/ T is set to 90 to 60%.

Further, the tightening margin when assembling the rim of the tire base is 3 to 15% of the ratio (TW-RW) / RW of the value obtained by subtracting the rim width from the bead width of the tire with respect to the rim width RW, which is 3 to 15%. Ratio (RD-TD) / RD of the value obtained by subtracting the large diameter of the bead of the tire from the large diameter of the rim with respect to the diameter RD is -1 to 5%
And the ratio of the value obtained by subtracting the small bead diameter of the tire from the small rim diameter to the small rim diameter RSD (RSD-TSD) / RSD
Is likewise 1 to 6% to prevent idling.

When the ratio (TW-RW) / RW of the value obtained by subtracting the rim width from the bead width of the tire with respect to the rim width of the tightening margin at the time of assembling the tire base body is smaller than 3%, the engaging force with the rim is increased. If it is larger than 15%, it may be too small, which may lead to idling.
Further, if it exceeds 15%, in the DT rim, the force of the rim to open in the axial direction after assembly is too strong, and cracks, that is, rim cracks, occur around the spout hole bolt of the rim with use. Easy and undesirable.

Similarly, the ratio (RD-TD) / RD of the value obtained by subtracting the large bead diameter of the tire from the large rim diameter with respect to the large rim diameter.
With respect to (1), if it is less than -1%, it becomes too loose with respect to the rim, which leads to idling, and if it is more than 5%, the assembling property with the rim also deteriorates.

The ratio (RSD-TSD) / RSD of the value obtained by subtracting the small diameter of the bead of the tire from the small diameter of the rim to the small diameter of the rim (RSD-TSD) / RSD is also less than 1%, which leads to idling and 6%.
If it becomes larger, the assemblability with the rim will deteriorate.

Therefore, the effect of various tightening margins at the time of assembling the tire base on the rim is further overlapped with the base rubber hardness, the inner diameter of the bead wire, the compression ratio of the rubber thickness just below the wire, etc., while ensuring the assembling property, It can prevent slipping and rim displacement.

With respect to the position of the bead wire in the axial direction of the tire according to claim 2, when there are two bead wires, the ratio of the distance BW1 in the axial direction of the bead wire to the tire bead width TW, BW1 / TW. 30
When the number of bead wires is 3 or more, the ratio of the distance BW2 in the tire axial direction between the outer bead wires near the rim flange to the tire bead width TW, BW2.
/ TW is set to 30 to 90%.

When the number of bead wires is two and BW1 / TW, which is the ratio of the axial distance BW1 between the bead wires to the tire bead width TW, is less than 30%,
Lateral rigidity of the tire decreases as it goes to the inner side, the lateral deflection, that is, the axial flexure of the tire increases, and rim displacement easily occurs. Also, when the TB or DT rim is assembled, the tip of the rim has the smallest small diameter on the inner peripheral surface of the tire. When passing near the small diameter part, the diameter near the small diameter part increases and it opens, but when the bead wire is close to the small diameter part as seen from the tire axial direction, the base rubber in this vicinity moves in the tread direction. It is difficult for it to escape (difficult to open), so cracks in the base rubber in the vicinity and scratches such as wrinkles in the circumferential direction are likely to occur. This can be resolved by slowly assembling,
It tends to occur at normal speed. On the other hand, if it is more than 90%, the axial distance from the rim flange portion becomes too small, and the wire may be exposed when used under particularly severe conditions and rim displacement occurs, which is not preferable. The TB and DT rims are YEAR BOOK (199) of Japan Automobile Tire Manufacturers Association (abbreviated as JATMA).
6) rim profile of 6), TB shown in the section: tilted seat rim,
DT: Split rim, this is the symbol T from JATMA
B, DT. This rim is generally used in the pneumatic cushion tire of the present invention.

When there are three or more bead wires, the ratio of the axial distance BW2 between the outer bead wires near the rim flange to the tire bead width TW, BW2 /
When the TW is smaller than 30%, the lateral rigidity of the tire is lowered to the inner side and the lateral deflection is increased to easily cause the rim displacement. Also, when the TB and DT rims are assembled, the tip of the rim is the inner peripheral surface of the tire. When passing near the smallest small-diameter part, the diameter near the small-diameter part increases and opens as it engages.However, if the bead wire is close to the small-diameter part as seen from the tire axial direction, the inner peripheral surface contact part The base rubber is hard to escape in the tread direction (difficult to open), and thus cracks, wrinkles, and other scratches are likely to occur. In this case as well, it can be resolved by slowly assembling, but it tends to occur at normal speed. On the other hand, if it is more than 90%, the distance to the rim flange portion becomes too small and the wire may be exposed when used under particularly severe conditions and rim displacement occurs, which is not preferable. Regarding the axial position, if the distances d between adjacent bead wires (FIG. 2) are all set to be the same, it is desirable that the rim effect can be uniformly exerted.

Further, the total tensile strength of all the bead wires to be used is in the range of 3000 to 30000 kgf, and it is possible to exhibit the anti-idling effect for a long time.
If it is less than 00 kgf, there is a shortage, 30,000 k
Greater than gf results in excessive quality.

According to a third aspect of the present invention, in the meridian and the section including the tire shaft of the tire base body, a bead flat portion TFW is provided on the bottom surface of the base portion at a symmetrical position about the tire equator so as to be parallel to the tire axis. Ratio of bead flat portion TFW to rim flat portion RFW of rim, TF
W / RFW is set to 0 to 150%.

The width of the bead flat portion TFW of the rim with respect to the rim flat portion RFW of the rim is related to the workability of the tire assembling, and by fitting the width of TFW / RFW = 0 to 1.5, the shape of the bead flat portion becomes almost uniform. However, the assembling property is good, and if it exceeds 1.5, the tightening portion becomes too large and the workability of assembling the rim deteriorates.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described.
1, 2 and 4 show a pneumatic cushion tire 1 of the present invention, which is a tire base body in which a tread portion 3, a base portion 2 and a bead wire 4 are built in symmetrically around the tire equator. FIG. 1 shows an embodiment when the number of bead wires is two, mainly 3.00-5, 4.00-8, etc.
It is applied to tires up to 00-8 size, and FIG. 2 shows an embodiment in which there are four bead wires 6.00-9, 6.
50-10, 7.0-12, 8.25-15, 18x
7-8, 21x8-9, 23x9-10, etc., mainly 5.0
Applies to tires larger than 0-8 size. Of course, for large tires, we sometimes use 5 or 6 bead wires. The diameter of the bead wire is about 0.94
0.98 mm (Cutting load: 135 kgf / mm ² or more
A high-strength steel wire of wire rod type SWRH72A) is wound in the circumferential direction and bundled into a cross section of 6 rows and 4 layers (excluding Table 7). This state is one bead wire , A plurality of these were used. The bundled cross-sections can be manufactured in various ways including 6 rows and 4 layers, and can be used for tires.

These techniques are applied to Aichi Tire Industry Co., Ltd. Japanese Patent Application No. 08-024322, which is a bead wire which has a structure in which the cross section has a plurality of stages and a plurality of rows, and the wires are covered and filled with rubber to be bundled. is there. Also, this Japanese Patent Application No. 08-024
As shown in the '322 patent, the bead wire can be used in the same manner even if it is covered with various fiber meshes, shavings, etc. to prevent the bead wires from coming loose. Furthermore, it is also possible to use a bead wire in the form of a bundle, instead of a bead wire in the form of a bundle, which is wound in a single ring shape having a thick and similar cross-sectional area (1 row x 1 step). Normally, in this case, various vulcanizing adhesives or the like are used to firmly adhere to the base rubber on the wire. FIG. 3 is a cross-sectional view of the rim, which is the profile (cross-sectional view) of the inclined seat rim (symbol TB) shown in the section of the Japan Motor Tire Association (abbreviation JATMA) rim profile as described above. . This rim is generally used in the pneumatic cushion tire of the present invention. FIG. 4 shows a state in which the tire base is mounted on the rim R. In this state, the rubber thickness T under the bead wire is compressed to T '.

Various rim assembly tests and actual vehicle tests using a forklift were carried out from Tables 1 to 8. Test conditions through Tables 1 to 8 ・ The used forklift is FG15 and the load is 5
00 kg.・ The road surface is concrete and the operating time is about 500 hours.
The course is a figure-eight turn of about 80m per lap, with an average speed of 10k
m / hr. .・ All tire sizes are 5.00-8 / 3.00D (Table 7
Used for the rear wheels of FG15 type forklifts, and the tire dimensions are 464 mm outer diameter and maximum width 128.
mm, tread width 114 mm. The dimensions around the bead of the tire, the bead width, the large bead diameter, and the small bead diameter were set to the specified tightening margin when the rim was assembled. The same applies to the width of the bead flat portion.・ The rim is a TB type of JATMA standard 8x3.00D, the rim width RW is 76 mm, and the rim large diameter RD is 202.4.
mm, small rim diameter RSD is 199.6 mm, rim flat width is 18 mm. The tread rubber of the tread portion has a JIS-A hardness of 65 degrees and is a conventional tread compound in which carbon black and various other chemicals are used in various diene rubbers such as natural rubber, SBR, and BR. Generally, hardness is 50-
It is set at about 70 degrees. The press used for the rim assembling work is a general solid tire assembling press of 15 to 60 tons. -For the base rubber of the base part, as shown in the patent of Aichi Tire Industry Co., Ltd .: Japanese Patent Laid-Open No. 8-282206, the type in which the polymer is natural rubber and SBR and the amount of styrene in the SBR is larger than usual is used. In addition, a rubber having a high hardness of 75 degrees or more was also used in combination with phenol resin. Also, the use of various chemicals such as carbon black is the same as in the prior art.

The symbols used in the test evaluations in Tables 1 to 8 mean that, in terms of idle rotation, ○ indicates a good condition with almost no idle rotation, Δ indicates a slight idle rotation, which is not preferable, and X indicates idle rotation. Not suitable. Regarding rim misalignment, ○ is a good condition with almost no rim misalignment, Δ is a little unfavorable because of rim misalignment, and X is a condition in which the rim misalignment is large and unsuitable for use. As for assembly workability, ○ is a good condition that there is almost no problem in workability and can be assembled with almost normal press load, △ is a little heavy and difficult to assemble, workability is poor and man hours increase unfavorably, X is load It is large and the assembly workability is quite poor and the number of man-hours increases and it cannot be applied.
In addition, a-mark that is seen in part indicates that the tire could not be assembled to the rim due to heavy load, and the tire could be damaged if it was forcibly assembled, and the test was impossible.

1. Effect of base rubber hardness on rim displacement

[0032]

[Table 1]

The fixed conditions in Table 1 are as follows (other conditions are the same as those in Tables 1 to 8 above). Base rubber hardness = 75 to 95 degrees Base height BH / H = 40% Bead wire inner diameter B = 103% of rim large diameter RD Rubber compression ratio T '/ T = 78% just below the bead wire Tire axial direction of bead wire Distance BW1 / TW = 5
Total tensile strength of 0% bead wire = 4800kgf Tightening margin of bead width when rim assembly (TW-RW) / RW =
Tightening margin of bead large diameter (RD-TD) / RD with 10% rim assembly
= 0% Tightening margin for small diameter bead when rim assembly (RSD-TSD) /
RSD = 3% Bead flat width TFW / RFW = 100%

It has been found that the increase in the hardness of the base rubber reduces the rim displacement, and at 80 degrees, there is no problem. The function of preventing the rim displacement mainly depends on the increase in the longitudinal and lateral rigidity of the tire, and the increase in the hardness of the base rubber directly leads to the increase in the rigidity of the tire. This tendency is the same even if an intermediate layer having a hardness intermediate between the tread portion and the base portion is provided. Further, if an intermediate layer having a hardness lower than that of the tread rubber (generally, about -10 degrees) is provided, the rim shift which is an absorption band for various impacts may be reduced. The ratio of the middle layer portion to the tire height H is usually about 10 to 50%.

2. Effect of base height BH / H (%) on rim displacement

[0036]

[Table 2]

The fixed conditions in Table 2 are as follows (other conditions are the same as those in Tables 1 to 8 above). Base height BH / H = 10 to 60% Base rubber hardness = 90 degrees Bead wire inner diameter B = 103% of rim large diameter RD Rubber compressibility directly below the bead wire T '/ T = 78% Bead wire tire axial direction Distance BW1 / TW = 5
Total tensile strength of 0% bead wire = 4800kgf Tightening margin of bead width when rim assembly (TW-RW) / RW =
Tightening margin of bead large diameter (RD-TD) / RD with 10% rim assembly
= 0% Tightening margin for small diameter bead when rim assembly (RSD-TSD) /
RSD = 3% Bead flat width TFW / RFW = 100%

It has been found that the rim displacement is reduced by the increase of the base height BH / H and becomes 20% at a level of no problem. The function of preventing the rim displacement is mainly dependent on the increase in the longitudinal and lateral rigidity of the tire, and the increase in the base height directly leads to the increase in the rigidity of the tire. This tendency is the same even if an intermediate layer having a hardness intermediate between the tread portion and the base portion is provided. Further, if an intermediate layer having a hardness lower than that of the tread rubber (generally, about -10 degrees) is provided, the rim shift which is an absorption band for various impacts may be reduced. Generally, a rubber compound having a good cushioning property and a small heat generation is used for the intermediate layer.

3. The influence of the inner diameter B of the bead wire and the compression ratio T '/ T of the rubber thickness just below the bead wire on the workability of idling and rim assembly

[0040]

[Table 3]

[0041]

[Table 4]

The fixed conditions in Tables 3 and 4 are as follows (other conditions are the same as those in Tables 1 to 8). Base height BH / H = 40% Base rubber hardness = 90 degrees Bead wire inner diameter B = Rim large diameter RD 101-109
% Compressibility of rubber just under the bead wire T '/ T = 100 ~
40% bead wire axial distance BW1 / TW = 5
Total tensile strength of 0% bead wire = 4800kgf Tightening margin of bead width when rim assembly (TW-RW) / RW =
Tightening margin of bead large diameter (RD-TD) / RD with 10% rim assembly
= -1 to 5% Tightening margin for small bead when assembling rim (RSD-TSD) /
RSD = 1 to 6% Width of bead flat part TFW / RFW = 100% When the rim is assembled, there is a wide margin between the large diameter bead and the small diameter bead. Because the shape of is composed of straight lines (Fig. 1,
2), the compression rate T '/ T of the rubber under the bead wire is 40
In order to set the specified value in the range of up to 100%, it is necessary to change the bead large diameter value and the small diameter value correspondingly. Therefore, the bead diameter is appropriately set within the above range.

When the inner diameter B of the bead wire was 101%, the idling resistance was good, but the bead wire came too close to the rim, making it difficult to assemble. In addition, there is a risk that the bead wire may come into contact with the vehicle while traveling, and there is a risk that cracks and the like will occur. On the other hand, at 108%, regardless of the compression ratio, this time the rubber thickness just below the bead wire became too thick when the rim was assembled, and it was not possible to obtain a sufficient tightening force, and at the beginning it eventually led to idling.

Further, the compressibility of the rubber thickness just below the wire in the meridional section of the tire including the tire shaft before the rim assembly is
When T '/ T = 95%, the compressibility of the rubber decreased and the reaction force was lost, resulting in idling. When T '/ T = 50%, the compression ratio became too large and the hoop effect became so strong that the workability of assembling the rim deteriorated.

Therefore, the inner diameter B of the bead wire is set to 102 to 107% of the large diameter RD of the rim, and T'when the rim is assembled.
Compressing and setting / T to a thickness of 90 to 60% is a basic requirement to prevent slipping while ensuring the assemblability. Of course, this applies not only to the present embodiment but also when using three or more bead wires and tires of other sizes.

Furthermore, when three or more bead wires are used, the inner diameter B of the bead wire is not always the same.
Need not be used, and the inner diameter B may be changed within the scope of the present invention depending on the axial position of the tire. For example,
For example, the inner diameter B is increased from the vicinity of the small diameter portion of the tire toward the large diameter portion, which is symmetrical about the tire equator.

4. Influence of various tightening margins around the bead when assembling the tire base rim on idling and assembling workability

[0048]

[Table 5]

The fixed conditions in Table 5 are as follows (other conditions are the same as those in Tables 1 to 8 above). Base rubber hardness = 90 degrees Base part height BH / H = 40% Bead wire inner diameter B = 103% of rim large diameter RD Rubber compression ratio T '/ T = 78% just below the bead wire Axial direction of the bead wire Distance BW1 / TW = 5
0% Tightening margin of bead width when rim assembly (TW-RW) / RW =
2-18% Tightening margin for large diameter bead when rim assembly (RD-TD) / RD
= -2 to 7% Tightening margin for small bead when rim assembly (RSD-TSD) /
RSD = 0 to 8% Bead flat width TFW / RFW = 100%

Tightening margin of tire bead width (TW-RW)
When / RW was 2%, the mating force with the rim was too small, which led to idling. At 18%, the work of assembling with the rim was too hard and the assembling press was overloaded.

Similarly, the tightening allowance of the large diameter bead (RD-T
Regarding D) / RD, when it became -2%, it became too loose and slipped, and when it became 7%, it became impossible to assemble with the rim.

Tightening margin for small diameter beads (RSD-TSD)
As for / RSD, when it was 0%, it slipped, and when it was 8%, the ease of assembly with the rim deteriorated, and in some cases there was some damage near the small diameter part.

Therefore, (TW-RW) / RW is 3 to 15
%, (RD-TD) / RD is -1 to 5%, (RSD-T
Since SD) / RSD is 1 to 6%, idling is prevented and rim assembly workability is also good.

5. Influence of the position BW1 / TW of the bead wire in the axial direction of the tire on rim displacement and the like

[0055]

[Table 6]

The fixed conditions in Table 6 are as follows (other conditions are the same as those in Tables 1 to 8). Position of bead wire in tire axial direction BW1 / TW = 2
0 to 70% Base rubber hardness = 90 degrees Base part height BH / H = 40% Bead wire inner diameter B = 103% of rim large diameter RD Rubber compression ratio T '/ T = 78% just below the bead wire Total tensile strength = 4800kgf Tightening margin of bead width when rim is assembled (TW-RW) / RW =
Tightening margin of bead large diameter (RD-TD) / RD with 10% rim assembly
= 0% Tightening margin for small diameter bead when rim assembly (RSD-TSD) /
RSD = 3% Bead flat width TFW / RFW = 100%

When BW1 / TW, which is the ratio of the tire axial width BW1 between the bead wires to the tire bead width TW, becomes 20%, the lateral rigidity of the tire is lowered to the inner side and the lateral or axial direction of the tire is decreased. Deflection increased and rim displacement occurred. Furthermore, when the TB rim is assembled, when the tip of the rim passes near the small diameter portion with the smallest tire inner diameter, the bead wire is close to the small diameter portion,
The base rubber in the vicinity of this area was difficult to escape in the tread direction (difficult to open), and cracks, wrinkles, and other scratches were found in this area. In this case, the occurrence of scratches could be prevented by slowly inserting the rim, but this is not desirable in terms of man-hours.
On the other hand, if it exceeds 90%, the distance in the axial direction from the rim flange portion becomes too small and the wire may be exposed when used under particularly severe conditions and rim displacement occurs, which is not preferable. The TB rim is the inclined seat rim as described above. Further, although not in the present embodiment, it has been found that a DT rim having a two-divided rim has substantially the same result because the rim has the same dimensions. This rim is generally used in the pneumatic cushion tire of the present invention.

Similarly, even if the number of bead wires is three or more, if the ratio BW2 / TW of the tire axial width BW2 between the outer bead wires near the rim flange to the tire bead width TW, BW2 / TW, is less than 30%, Lateral rigidity of the tire decreases as it passes through the inside, and lateral deflection increases and rim misalignment easily occurs. Since the bead wire is close to the small diameter part when viewed from the axial direction, the base rubber is difficult to escape in the tread direction (difficult to open) and also cracks and the like are likely to occur. On the other hand, if it is more than 90%, the distance to the rim flange portion becomes too small and the wire may be exposed when used under particularly severe conditions and rim displacement occurs, which is not preferable. In this case, the distance d between adjacent bead wires (Fig. 2)
It is desirable that all are the same and that they are evenly spaced so that the rim effect can be exerted evenly on the rim. Therefore, in any case, BW1 / T
The appropriate range of W and BW2 / TW is 30 to 90%.

6. Effect of total tensile strength of bead wire on idling

[0060]

[Table 7]

The fixed conditions in Table 7 are as follows (other conditions are the same as those in Tables 1 to 8 above). Tire size 5.00-8 / 3.00D, 6.50-10 / 5.00
Uses F TB rim. The forklift is also FG15.
5.00-8 / 3.00D is at the rear wheel, 6.50-10
/5.00F was attached to the front wheel. Total tensile strength of bead wire = 3200 to 1440
0kgf Base rubber hardness = 90 degrees Base part height BH / H = 40% Bead wire inner diameter B = 103% of rim large diameter RD Rubber compressibility directly below the bead wire T '/ T = 78% Bead wire tire axial direction Distance BW1 / TW = 5
0% Tightening margin of bead width when rim assembly (TW-RW) / RW =
Tightening margin of bead large diameter (RD-TD) / RD with 10% rim assembly
= 0% Tightening margin for small diameter bead when rim assembly (RSD-TSD) /
RSD = 3% Bead flat width TFW / RFW = 100%

Tire 5.00-8 shown in the embodiment
/3.00D and 6.50-10 / 5.00F showed almost no idling, and the total tensile strength was 3000 to 3
It was found that in the range of 0000 kgf, the anti-idling effect can be exhibited for a long period of time. Further, the number of bead wires can be set to 5 or 6, and the row x layers of the bead wires can be arbitrarily set to be flat such as 4x4 to 8x8 or 3x6, 4x8. Further, although not in the present embodiment, the DT rim having a split rim has the same rim size, and thus similar results are obtained.

7. Width of bead flat portion TFW / RFW
Of Rim on Rim Assembly Workability and Idling Performance

[0064]

[Table 8]

The fixed conditions in Table 8 are as follows (other conditions are the same as those in Tables 1 to 8 above). Base rubber hardness = 90 degrees Base part height BH / H = 40% Bead wire inner diameter B = 103% of rim large diameter RD Rubber compression ratio T '/ T = 78% just below the bead wire Axial direction of the bead wire Distance BW1 / TW = 5
0% Tightening margin of bead width when rim assembly (TW-RW) / RW =
Tightening margin of bead large diameter (RD-TD) / RD with 10% rim assembly
= 0% Tightening margin for small diameter bead when rim assembly (RSD-TSD) /
RSD = 3% Bead flat width TFW / RFW = 0 to 190%

When TFW / RFW = 170%, the rim assembly property deteriorated. Therefore, TFW / RFW is 0 to 150%
The range is good.

[0067]

As described above, in the pneumatic cushion tire for industrial vehicles according to claims 1 to 3,
Various inconveniences that tend to occur in conventional tires have been solved. With the pneumatic cushion tire of the type of the present invention, the base rubber hardness, the base height, the position of the bead wire on the tire cross section, the tire rim assembly The tightening margin at the time and the shape of the bead flat part on the bottom of the beat can be optimally set, the basic property around the bead part that does not impair the assembling property to the rim, maintains the anti-idle property, and prevents the rim from shifting. It is possible to obtain a pneumatic cushion tire for industrial vehicles with improved performance.

Of course, the same effect can be obtained by providing various intermediate layers between the tread portion and the base portion. Incidentally, the intermediate layer may be one layer or two layers and may be 10 to 5 with respect to the tire height H.
0% is preferably about 20 to 40%, and the hardness is generally set to an intermediate value between the tread portion and the base portion or a value 5 to 15 degrees below the tread portion, preferably about 5 to 10 degrees. Therefore, the cushioning property, heat generation property, etc. can be further improved. In addition, as the compounding of the middle layer rubber, natural rubber alone or a combination of natural rubber and a low heat generating polymer such as BR, and a low heat generating carbon black such as FEF type is generally used.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a pneumatic cushion tire for an industrial vehicle having two bead wires according to an embodiment.

FIG. 2 is a sectional view of a pneumatic cushion tire for industrial vehicles having four bead wires according to an embodiment.

FIG. 3 is a cross-sectional view of a TB rim for an industrial vehicle according to an embodiment.

FIG. 4 is a cross-sectional view of the pneumatic cushion tire for an industrial vehicle according to the embodiment mounted on a TB rim for an industrial vehicle.

[Explanation of symbols]

1 ... Tire base 2 ... Base part 3 ...
Tread part, 4 ... Bead wire H ... Tire height BH ... Base part height T
W ... Tire bead width BW1 ... Distance in the tire axial direction when there are two bead wires TD ... Large bead diameter of tire B ... Inner diameter TSD of bead wire ... Small bead diameter of tire TFW・ ・ ・ Width of the bead flat portion of the tire d ・ ・ ・ Distance between bead wires R ・ ・ ・ TB rim RW ・ ・ ・ Rim width RD ・ ・ ・ Large rim diameter RSD ・ ・ ・ Rim small diameter RFW
Width of rim flat part T ... Rubber thickness under bead wire T '... Rubber thickness under bead wire when rim is assembled

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Mitsuru Ogawa 1108 Otsubo, Taraku-cho, Kasugai-shi, Aichi Prefecture Kasugai Works, Aichi Tire Industry Co., Ltd. (72) Tatsu Murata 1108 Otsubo, Taraku-cho, Kasugai-shi, Aichi Prefecture Aichi Tire Industry Co., Ltd.Kasugai Plant (72) Inventor Kazuyoshi Ueno 1108 Otsubo, Taraku-cho, Kasugai-shi, Aichi Aichi Tire Industry Co., Ltd. Kasugai Plant (72) Inventor, Kaga Kaga Otsubo, Kasugai-shi, Aichi 1108 Aichi Tire Industry Co., Ltd. Kasugai Works (72) Inventor Hiroshi Tanemura Otsubo, Taraku-cho, Kasugai-shi, Aichi Prefecture 1108 Aichi Tire Industry Co., Ltd. Kasugai Works (72) Inventor Tetsunori Makino Taraku-cho, Kasugai-shi, Aichi 1108 Otsubo, Aichi Tire Industry Co., Ltd. Kasugai Plant (72) Inventor Mitoshi Miyase 1108 Otsubo, Taraku-cho, Kasugai-shi, Aichi Aichi Tire Industry Co., Ltd., Kasugai Works (72) Inventor Satoru Asano 1108, Otsubo, Taraku-cho, Kasugai-shi, Aichi Prefecture Kasugai Works, Ltd. (72) ) Inventor Haruyuki Morimoto 1108 Otsubo, Taraku-cho, Kasugai-shi, Aichi Prefecture Kasugai Plant, Aichi Tire Industry Co., Ltd. (72) Hisaki Kato 1108 Otsubo, Kasugai-shi, Aichi Prefecture Kasugai Plant, Aichi Tire Industry Co., Ltd. (56) References JP-A 8-216613 (JP, A) JP-A 8-282206 (JP, A) JP-A 6-106908 (JP, A) JP-A 8-91011 (JP, A) ( 58) Fields investigated (Int.Cl. ⁷ , DB name) B60C 7 / 00,15 / 00,15 / 02

Claims (3)

(57) [Claims] Claims: 1. A pneumatic cushion tire for industrial vehicles, comprising a tire base having a tread portion and a base portion or a tread portion, a middle layer portion and a base portion integrated with each other, wherein the base portion rubber has a JIS-A spring type hardness (JI).
S-K6301) is 80 to 100 degrees, and the value of the height BH of the base portion relative to the tire height H in the meridional section of the tire including the tire shaft, BH / H is 20 to 70%.
The plurality of bead wires wound along the circumferential direction are built in the base portion at symmetrical positions about the tire equator, and the inner diameter B of the bead wires is 102 of the rim large diameter RD to be used. About the compression rate of the rubber part under the bead wire having an inner diameter of ˜107% and under the bead wire by the rim assembly, when the rim is assembled with respect to the rubber thickness T just under the bead wire in the meridional section of the tire including the tire shaft before the rim assembly, Ratio T ′ / of rubber thickness T ′ of meridional section of tire including tire shaft
T is in the range of 90 to 60%, and the tightening margin at the time of assembling the rim of the tire base is rim width RW.
The ratio (TW-RW) / RW of the value obtained by subtracting the rim width RW from the tire bead width TW is 3 to 15%, and the bead large diameter T from the rim large diameter RD to the rim large diameter RD is
The ratio of the value obtained by subtracting D (RD-TD) / RD is -1 to 5%, and the ratio of the value obtained by subtracting the small bead diameter TSD of the tire from the small rim diameter RSD to the small rim diameter RSD (RSD-TS
D) / RSD is 1 to 6%, and is a pneumatic cushion tire for industrial vehicles. 2. The bead wire, when there are two bead wires, a ratio of a tire axial width BW1 between the bead wires to a tire bead width TW, BW1 / TW.
Is 30 to 90%, and when there are three or more bead wires, the ratio of the axial distance BW2 between the outer bead wires near the rim flange to the tire bead width TW, BW2 / TW, is 30 to 90%. The pneumatic cushion tire for industrial vehicles according to claim 1, wherein the total tensile strength of all the used bead wires is 3000 to 30000 kgf. 3. A rim flat portion of a rim to be used in which a bead flat portion TFW is provided on a bottom surface of a base portion in a symmetrical position about a tire equator in a meridional section including a tire axis of the tire base body in parallel with the tire axis. The ratio of the bead flat portion TFW to RFW, TFW / RFW is 0 to 15
The pneumatic cushion tire for industrial vehicles according to claim 1 or 2, wherein the content is 0%.