JPH0240521B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a solid tire with improved slip resistance and the like, which is based on embedding metal wires in tread rubber. [Prior Art] In general, solid tires are widely used as tires for industrial vehicles such as forklifts at construction sites, factories, cold storage rooms, etc.
Since tires are usually used under high load and low speed conditions, so-called plain tires, which have relatively high hardness and do not have patterns formed on their surfaces, are used. As a result, when used in a refrigerated room or on a frozen road surface, the slip resistance is extremely poor, impairing safety. Therefore, as a solution to one part of the problem, as illustrated in FIG. 1, a plurality of wire meshes b are wound concentrically in a spiral shape, and these are embedded in a tread rubber a, and furthermore,
As disclosed in Japanese Utility Model Application No. 51-118603 and shown in FIG. 2, a structure in which a U-shaped metal wire b is embedded in a tread a has been proposed. [Problem to be solved by the invention] However, in the former case, it is extremely difficult to embed the wire mesh b in the tread rubber a in correct concentric circles, or to wind it up spirally without making it eccentric. As a result, uneven wear occurs on the surface of the tread rubber a with use. In addition, in the latter case shown in FIG. 2, as disclosed in the attached specification of the same issue, the metal wire b has its outer end embedded in a sheet and then removes the sheet after forming, or Since the timer is molded by inserting the end of the metal wire b into the inner hole of the mold, the timer has the disadvantage that the end of the metal wire is exposed on the outer peripheral surface. In addition, the outer circumferential surface of the tread a is flat, resulting in poor slip resistance, and the gap between the metal wire b and the base band c is too large, resulting in poor durability. The present invention aims to solve these problems and provide a solid tire that can improve slip resistance on frozen road surfaces and improve driving performance while maintaining the elasticity and shock-absorbing properties inherent in rubber tires. [Means for Solving the Problems] The present invention is characterized in that liquid urethane is injected into an annular cavity of a mold in which the baseband is arranged concentrically and on the center side, and is cured to adhere to the baseband. A tread made of urethane rubber having a JISA hardness of 80 to 90 degrees is provided, and the tread rubber has leg pieces at both ends of the bottom piece facing outward in the radial direction, and a tread thickness of 15 to 90 degrees between the bottom piece and the base band. In addition to containing metal wires buried with a 50% gap, the outer circumferential surface is cut so that the tread radius of the outer circumferential surface is 300 to 700 mm, and the cut end surface of the metal wire is exposed flush with the outer circumferential surface. On the other hand, it is a solid tire in which the horizontal pitch of the cut end surface of the metal wire in the tire axial direction is 3 to 10 mm, and the vertical pitch in the circumferential direction is larger than the horizontal pitch and 5 to 20 mm. [Function] The tread is formed by injecting liquid urethane into the mold cavity and curing it, so it firmly adheres to the baseband. In addition, since it is made of urethane with a JISA hardness of 80 to 90 degrees, it has excellent durability and blends well with the road surface, contributing to improved slip resistance. Further, the metal wire is buried in the tread, and the tread radius is finished by cutting to 300 to 700 mm after forming, so the cut end surface of the metal wire is exposed flush with the outer peripheral surface. Therefore,
The combination of the tread radius and the exposed metal wire improves slip resistance, and since the metal wire is exposed flush with the outer circumferential surface, there is no protrusion of the metal wire, making it easier to bend during use and prevent road surface damage. Prevent damage. Furthermore, since the vertical pitch in the circumferential direction of the metal wire is larger than the horizontal pitch in the axial direction of the tire and is within a predetermined range, it can be suitably used for forklifts that tend to slip when turning sideways. Furthermore, by increasing the vertical pitch, the tread rubber can be easily compressed and deformed when it comes into contact with the road surface, and the spike effect can be enhanced. Furthermore, since the gap between the bottom piece of the metal wire and the baseband is set to 15 to 50% of the tread thickness, durability is improved and wear life is increased. [Example] An example of the present invention will be described below based on the drawings. In FIG. 3, a solid tire 1 of the present invention is shown.
In this example, a metal wire 4 is embedded in a tread 3 attached to a cylindrical baseband 2. The metal wire 4 is a single wire made of metal such as steel, or a cord made by twisting multiple single wires, and the wire diameter is 0.1 mm or more and 2 mm.
Approximately U is used, and relatively long leg pieces 4b, 4b are bent and formed on both ends of the bottom piece 4a.
form a letter shape. The metal wire 4 is buried with the bottom piece 4a facing the baseband 2 side, the leg pieces 4b and 4b facing outward in the radial direction of the tire, and with a gap between the bottom piece 4a and the baseband 2. Note that metal wire 4
The bottom piece 4a is buried parallel to the tire axial direction. Said gap t is at least 15% of the thickness T of the tread 3. This is because if the distance t between the bottom piece 4a of the metal wire 4 and the baseband 2 is too small, air will remain in the vicinity of the bottom piece 4a when liquid urethane is injected during tire manufacturing, and peeling will easily occur. On the other hand, if the interval t is too large, the tread 3
As the bottom piece 4a wears down, the wear life until the bottom piece 4a is directly exposed to the ground surface decreases. Therefore, it is desirable that the thickness be 50% or less of the thickness T of the tread rubber 3. Further, the lateral pitches l1 and l2 in the tire axial direction between the two ends of the metal wire 4 are both in the range of about 3 to 10 mm, and the pitch in the circumferential direction of the tire is in the range of about 5 to 20 mm. This moderately improves slip resistance. Furthermore, the vertical pitch in the circumferential direction is larger than the horizontal pitches l1 and l2, as clearly shown in FIG. This is because forklifts and the like tend to slip laterally when turning, and to prevent this, the lateral pitches l1 and l2 are made smaller than the vertical pitch. On the other hand, the vertical pitch is set within the above range and larger than the horizontal pitches l1 and l2 because it is necessary to enhance the effect of the spikes of the metal wire 4 as the tread 3 undergoes compressive deformation due to contact with the road surface. The tread 3 is made of polyurethane, and as described later, the tread radius of the outer peripheral surface 5 is cut by cutting the outer periphery of the formed body after curing with the metal wire 4 interposed therebetween.
The RT is set in the range of about 300 to 700 mm. Although the slip resistance increases as the tread radius RT decreases, if the tread radius RT is made smaller than 300 mm, wear of the tread rubber 3 is accelerated, and therefore it is set within the above range. Note that if it exceeds 700 mm, the slip resistance will decrease. By the cutting, the tread 3 has its outer peripheral surface 5
The cut end surface 4c of the metal wire 4 is exposed flush.
In this way, the cut end surface 4c of the metal wire 4 is
By exposing the outer surface 5 of the vehicle, slips can be reliably prevented during driving. In addition, it can be said that the higher the hardness of Toread 3, the better from the viewpoint of load capacity, but from the viewpoint of slip resistance, JISA hardness of 80 to 80 is preferred.
The range should be 90°. This is because, for the metal wire 4 which has a spike effect, if the hardness of the rubber forming the outer peripheral surface of the tread is smaller than JISA80°, the amount of deformation of the ground plane becomes large and the amount of protrusion from the outer peripheral surface of the metal wire 4 becomes relatively large. This increases the size of the road surface, making it more likely to damage the road surface. On the other hand, the hardness
When the angle is larger than 90°, the amount of deformation becomes too small and the spike effect caused by the metal wire 4 is reduced. Therefore, by setting the ground pressure within the above range, it is possible to obtain a preferable substantially constant ground contact pressure, suppress damage to the road surface, enhance the spike effect, and exhibit durability. Furthermore, the solid tire 1 is made by creating a band-like body 9 in which the tips of the legs 4b of the metal wires 4 are embedded in a rubber plate 7, as shown in FIG. 4, for example, and as illustrated in FIG. It is attached to the outer inner surface of an annular cavity 11 of a mold 10 in which the baseband 2 is arranged concentrically and on the center side, and liquid polyurethane rubber, that is, liquid urethane, is injected into the cavity 11 to form a hardened molded body. In addition, as described above, this molded body is shaved off with a lathe and finished into the tread radius RT, thereby exposing the cut end surface 4c of the metal wire 4 on the outer circumferential surface 5. [Example] A solid tire having the structure shown in FIG. 3 and having a tire size of 12 x 6 x 6 1/2 was manufactured based on the specifications shown in Table 1. Note that the tread thickness T is 70 mm. This was attached to the drive wheels of a TCM and FRSB-15 test vehicle, and the vehicle was pulled on dry and wet roads with a wheel load of 1050 kg, and the maximum traction force until slippage occurred was measured. The results are shown as relative values with Comparative Example 1 as 100. Furthermore, the amount of wear was measured after driving the actual vehicle on a concrete road surface for 2000 km. The results are shown as wear resistance. In addition, the road surface damage property, which is the measured state of road surface damage after driving, is similarly expressed as a relative value. In both cases, the higher the numerical value, the better the result. From Table 1, it can be seen that the traction force of all the examples of the present invention is greatly improved. Furthermore, from Example 2 and Comparative Example 1, the training radius (RT)
From Example 1 and Comparative Example 3, it can be seen that the difference in hardness affects traction. 〔Effect of the invention〕

【table】

[Table] The solid tire of the present invention has excellent slip resistance, particularly slip resistance during turning, and is durable due to the combination of the above-mentioned configurations.

[Brief explanation of drawings]

1 and 2 are side views of a conventional solid tire, FIG. 3 is a sectional view illustrating an embodiment of the present invention, FIG. 4 is a perspective view illustrating a band-shaped body, and FIG. 5 is a side view of a conventional solid tire. 1 is a cross-sectional view schematically showing a method for manufacturing a solid tire. 2... Base band, 3... Tread, 4... Metal wire, 4a... Bottom piece, 4b... Leg piece, 4c... Cut end surface,
5...Outer peripheral surface, 7...Band-shaped body, RT...Tread radius, t...Spacing, T...Tread rubber thickness.

Claims (1)

[Claims] 1 Liquid urethane is injected into the annular cavity of the mold in which the baseband is placed concentrically and on the center side, and when it hardens, it adheres to the baseband and is made of urethane rubber with a JISA hardness of 80 to 90°. comprising a tread, the tread comprising:
The leg pieces at both ends of the bottom piece should be oriented radially outward, and there should be a tread thickness of 15 mm between the bottom piece and the base band.
In addition to containing metal wires buried with a gap of ~50%, the outer peripheral surface is cut so that the tread radius of the outer peripheral surface is 300 to 700 mm, and the cut end surface of the metal wire is flush with the outer peripheral surface. A solid tire in which the cut end surface of the metal wire is exposed, and the horizontal pitch in the tire axial direction is 3 to 10 mm, and the vertical pitch in the circumferential direction is larger than the horizontal pitch and 5 to 20 mm.