Technical Field

The present invention relates to tire cord fabric tabbies located at both ends of a tire cord fabric roll. The fabric rolls are tied together by splicing them at the tabby sections.

Background of the Invention

Tire cord fabric is the reinforcement material used in tires. A tire cord fabric comprises a plurality of parallel warps in longitudinal direction and a plurality of weft material interwoven with said warps perpendicular to each other. Weft material in tire cord fabric is not a load bearing or reinforcing element for tire building. However the weft maintains the regular spacing of the warps throughout the fabric length and width. The tabby is woven at the fabric ends to fasten the warps together when the fabric roll is cut and removed from the weaving loom and additionally the tabby section is used for splicing of the fabric rolls to each other at the dipping line for continous process.

The length of a tire cord fabric is about 1000 meters while the length of a tabby is about 30 to 60 cm. The width of a tire cord fabric roll is about 150 cm. The tire cord fabric has weft yarns with low weft density around 5 to 10 wefts per decimeter, however on the tabby part of the fabric the weft density is as high as 30 to 60 wefts per decimeter. The high weft density at the tabby section of the fabric is necessary for the strength of the splice to withstand the high tension applied during hot stretching of the fabric in the dip unit. Due to the increased weft density in the tabby, the warp crimp level in this area is also higher compared to the rest of the fabric. During hot stretching process in the dip unit, the applied tension on the fabric results in the crimp transfer from the warp to the weft and the difference of the crimp transfer between the tabby and the fabric sections results in the narrowing of the tabby. This narrowing of the tabby results in the nonuniform warp distribution, weft brakages followed by fabric splitting along the fabric, folding of the fabric, inefficient working of the dewebber, irregular dip pick up. All such defects resulting a high level of scrap both during dipping and calendering of the fabric in the areas adjacent to the narrowed tabby.

The commonly used weft materials in the body of tire cord fabric are cotton, rayon, synthetic yarns or high elongation multicomponent yarns. The weft yarns in the tabby section were cotton in the past, today there are core-sheath yarns made of glass as core and mantled with natural or synthetic fiber.

An example of a tabby weft or fill yarn is described in EP 0077288 patent application explaining the fill yarn made of core and sheath, where the sheath is polymer coated and is wrapped to the core yarn. Reduced shrinkage of tabby portion of the fabric has been claimed by the use of such fill yarn in the tabby. The necessary presence of the core and sheath structure of EP0077288 and also the sheath comprised of foamed rubber adds an additional step to the manufacture and makes its manufacture complex and expensive.

Another example of tabby weft yarn is described in US 5342678 patent application similarly explaining a composite yarn comprising core of glass filaments mantled with fibers by a friction spinning technique. Tire cord fabrics undergo lateral narrowing when exposed to the dipping and hot stretching conditions. This narrowing effect is attributed to the wet shrinkage of the cotton weft yarn.

Brief description of the invention

The object of the present invention is to provide a tire cord fabric tabby comprising a composite weft yarn, wherein such composite weft yarn comprising metallic wire and cotton yarn.

It is another object of the present invention to provide a tire cord fabric tabby for solving the fabric narrowing problem.

It is another object of the present invention to provide a tire cord fabric tabby for reducing the amount of tire cord fabric scrap.

It is a further object of the present invention to provide a tire cord fabric tabby in a more economical way.

Detailed description of the invention

Specific aspects of the present invention is described in more detail with reference to the accompanying drawings as follows:

FIG. 1 represents the tire cord fabric construction after dipping and hot stretching process using metallic wire and cotton composite weft yarn in the tabby area of the present invention.

FIG. 2 represents the side view of Figure 1.

FIG.3 represents the side view of warp in the tabby section

FIG. 4 represents the side view of warp in the tire cord fabric section

FIG. 5 represents the side view of the metallic wire and cotton composite weft yarn

FIG. 6 represents the cross section of the metallic wire and cotton composite weft yarn

The items in the figures are numbered as follows ,

10. Tire cord fabric

11. Warp

12. Weft in fabric section

13. Composite weft in tabby section

14. Tabby

15. Metallic wire

16. Cotton yarn A cord fabric tabby (14) comprising a plurality of composite weft yarns (13) and a plurality of warps (11) perpendicular to the said composite weft yarn (13); and composite weft yarn (13) obtained by metallic wire (15) and cotton yarn (16) twisted together.

Usage of the composite weft yarn (13) in the tabby (14) section of a tire cord fabric (10) results in reduced fabric scrap during fabric manufacturing and calendering processes by reducing tabby narrowing. Compared to core and sheath structures, the present invention requires only twisting process to manufacture the composite weft (13) for the tire cord fabric tabby.

The advantage of using metallic wire (15) in the composite weft yarn(13) of the present invention compared to glass for example is that wire being not brittle shall make the composite weft more resistive to bending against the crimp transferring forces of the warp, resulting in a higher performing tabby.

Composite weft yarn (13) used in the present invention is made by twisting of cotton yarn strands (16) with steel or copper wire

Fw indicates the force applied to a single warp (11) during hot stretching process. Depending on the weft density in the tabby, the crimp angle of the warp yl develops a crimp transfer force on the weft by Fl = Fw Cos yl . As the weft density in the tabby increases, the crimp angle y decreases, as a result of this, the crimp transfer force from warp to weft increases (Figure 3).

Fw indicates the force applied to a single warp during hot stretching process. Depending on the weft density in the body of the fabric, the crimp angle of the warp, y2 develops a crimp transfer force on the weft by F2 = Fw Cos y2 (Figure 4).

Table 1 indicates the results of tests indicating the performance of different constructions of metal (15) and cotton (16) composite weft yarn (13) on the narrowing of the tabby (14). The tabby and the fabric width values in Table 1 are measured after dipping and hot stretching process.

Experimental findings in Table 1 indicate that the width difference between the fabric and the tabby was reduced and as a result of this, fabric folding and the amount of scrap was significantly reduced.

Table 1 : Metallic wire (15) and cotton (16) composite weft yarn (13) parameters and tabby performance values. [Table 1] [Table ]

The thickness of the metallic wire ranges from 40 micrometer to 150 micrometer, most preferentially 50 to 80 micrometer. The number of metal ply in the composite weft (13) is kept as 1, but it is possible to increase the number of metal ply. The metallic wire (15) can be stainless steel without any coating or can be galvanized steel. The copper can be bare copper without coating or can be coated with nickel. The stiffness of the stainless steel is relatively lower than that of galvanized steel. Stiffness of the metallic wire (15) has effects on the stability of the composite weft yarn causing kinking or wrinkling of the composite weft yarn (13). Copper is a softer material than steel and cause less problems.

Cotton yarn (16) thickness used in the composite weft (13) is Ne 20/1 or Ne 30/1 (Ne, English Cotton Count is based on the number of 840 yard lengths in one pound weight of yarn. The higher the English Cotton Count value, the finer the yarn i.e. the more yarn length in one pound). The present invention however should not be considered to be limited with cotton yarn numbers of Ne 20/1 and Ne 30/1. The number of cotton plies (16) in the composite weft (13) varies from 3 to 6 and is prefer- enentially 5.

Using metallic wire alone as tabby weft material would be impractical since the smooth surface will not allow such a weft to be thrown in air jet looms and also there shall not be enough binding to the warp strands. If the metal wire cotton composite weft is heavier than the drag force generated by the air jet then the composite weft (13) will not be carried in the air channel of the loom.If the composite weft is too thin and not straight then it will not be able to follow a straight path in the air channel and will strike to the sidewalls of the channel.

Cotton is the component to make the composite weft (13) fly across the air channel of the weaving loom. Cotton yarn (16) and metallic wire (15) are twisted together in the range of 150 to 250 tpm, preferentially at 150 tpm. Direction of twisting can be S or Z. The level of twist shall be adjusted so that the composite weft shall have uniform properties. If the twist level is too low, the plies separate from each other and the integrity of the composite weft will be lost. If the twist level is too high, the composite weft wrinkles and not possible to process the yarn in weaving. If the composite weft is not produced properly, metallic part undergoes bending and such problem prevents the weft insertion during weaving across the air channel. The experiments carried out on cotton yarn showed that cotton does not shrink under fabric dipping conditions.