GB1559380A - Belting structure carcass and method of forming same - Google Patents

Description

(54) IMPROVED BELTING STRUCTURE CARCASS AND METHOD OF FORMING SAME (71) We, BBA GROUP LIMITED, a British Company of P. O. Box No. 20, Cleckheaton, West Yorkshire, do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to a belt carcass and to a method of forming the same, and is particularly concerned with a belt carcass in which difficulties concerning take-up of an impregnant by the yarns of the carcass may be alleviated.

A commonly-used form of belting for industrial conveyor or elevator applications incorporates a solid woven carcass impregnated and coated with a suitable elastomer- ic material to protect the carcass. U. K.

Patent No. 1,386,795 describes a solid woven carcass as one in which binder warp yarns of the carcass are woven-in so as to bind all the plies employed in providing the required carcass thickness.

To provide the flexibility and tensile and tear strength required in industrial belting, prior proposas have been to employ multifilament synthetic yarns in suitable numbers for binder warp yarns that are woven-in to bind the carcass structure in solid woven form, while using outwardly disposed warp of spun yarn in the plies to build the required carcass thickness and promote good adhesion of the impregnant with the carcass. Such proposals have resulted in generally satisfactory belting, but various production problems and disadvantages have arisen.

Primarily, the filament yarns used for the binding warp must be supplied on expensive flanged spools because their slick nature will not allow them to be wound into packages without end supports. This in turn requires that the filament supply must be beamed for use in weaving and when a running beam supply is exhausted, there is time wastage while it is replaced. Furthermore, some difficulty is encountered in controlling the tension of the binder warp yarns because of the tendency of the filament to slip in the feed roll system through which it is handled in being delivered for weaving.

A further problem arises in that filament is not readily receptive to take-up of impregnant, and it is an object of the present invention to provide a belt carcass, and a method of forming the same that alleviates this problem as well as those aforementioned, and allows weaving efficiency to be increased and A more homogeneous and sounder belt carcass to be produced.

According to the present invention there is provided a belt carcass comprising a ply formed of warp yarns and weft yarns, and wherein predominantly each of such yarns is formed of a plurality of composite units of filament and staple fibre components with a respective filament component being twisted with the staple fibre component of each such composite unit, the filament component being of substantially smaller cross-sectional area than the staple fibre component and being twisted therewith so as to predominantly expose the staple fibres in that composite unit.

Two or more plies of the belt carcass formed in accordance with the immediately preceding paragraph may be woven together by binder warp yarns predominant- ly each of which is formed compositely of filament and staple fibre components with a respective filament component being twisted with the staple fibre component of each such composite unit of the binder warp yarn, the filament component being of substantially smaller cross-sectional area than the associated staple fibre component and being twisted therewith so as to predominantly expose the staple fibres in that composite unit.

The filament components of the respective yarns should be present in such proportions therein as, in aggregate, to supply the flexibility and tensile and tear strength required in the belting, and the staple fibre components thereof, which serve to bulk the yarns, also provide a sorption action throughout the yarns by which integrating impregnant is caused to penetrate the solid woven carcass readily and effectively despite the proportion of filament components contained therein.

In a preferred embodiment, the or each composite unit of filament and staple fibre components is such that the staple fibre component defines a core about which the associated filament component is twisted to predominantly expose the core, such composite units being known as core yarn units.

Preferably the aforedescribed filament component is in multi-filament form and each yarn that is formed compositely of filament and spun fibre components may comprise two or more composite units plied together.

Conveniently impregnation is conducted after weaving of the belt carcass, but in order to ensure a thoroughly homogeneous coating, the warp and binder warp yarns may be coated with impregnant in the loom.

According to a further aspect of the present invention there is provided a method of forming a belt carcass which comprises creeling warp yarns, feeding a sley from said creeled warp yarns to a loom for weaving a ply of belt carcass, inserting weft yarns to complete the belt ply, predominantly each of such warp and weft yarns being as described hereinbefore, and impregnating the carcass with a protective material.

One embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 7 is a schematic weave diagram of a solid woven belt carcass in accordance with the present invention; Figure 2 is an enlarged fragmentary illus- tration of a representation warp yarn used in the belt carcass of Figure 1, and Figure 3 is a flow diagram illustrating a method of forming a belt carcass in accordance with the present invention.

The embodiment of belt carcass illus- trated in Figure 1 comprises warp yarns 10 arranged warpwise in two belt plies with weft or filling yarns 12 inserted in each ply in 2-2 warp rib fashion, while four binder warp yarns 14 alternate with pairs of warp yarns 10 for each ply and are woven-in with the weft yarns 12 in a 4-4 pattern to bind the plies in solid woven form.

All of the yarns 10, 12 and 14 are formed compositely of filament and staple fibre components as shown in Figure 2, in which one of the warp yarns 10 is indicated as a plied strand of composite units in each of which spun stable fibre components form a core 10'and filament components 10"are twisted therewith to form a core yarn unit.

The composite units may be other than core yarn units, for example if the composite units are formed by doubling. However, core yarn units are preferred both because an advantageously stable composite structure is obtained in this way, and because the resulting structure enables predominant exposure of the spun staple fibre core material 10'whereby effective impregnant penetration of the carcass is allowed. The composite units may be combined as necessary for a required cross-section by, for example, doubling, twisting or spinning. Where two or more composite units in the form of core yarn units are combined, the resulting yarn is hereinafter referred to as a core yarn.

A typical belt carcass structure constructed in accordance with Figure 1 and suited for producing belting of minimum warp tensile strength of 4,000 pounds per inch of belt width and minimum weft tensile strength of 1,500 pounds per inch, employs warp yarns 10 of four 1. 5 composite units in which a 1. 5 160i) denier polyester filament component 10"is wrapped around each polyester stapLe fibre spun core 10'with the fi) ament component being provided in multi-filament form for twisting with each core 10'. It will be understood that the term "polyester"ls meant to designate polyethylene tcrephthatate filament or fibre.

The weft or rating yarns 12 and inner or binder warp y. trns 14 are in turn each similarly formed of polyester in two 1.5 composite units in which a 1.5 1600 denier filament component is wrapped around each staple fibre core, and a sley is provided for the weave, incorporating twenty-five warp yarns 10 and twenty-five binder warp yarns 14 per inch, which sley is woven at a pick count of fourteen double picks of filling 12 per inch. This typical carcass structure is subject to wide variation both as to weave pattern and materials used depending on the requirements of the belting to be produced.

Thus, only a single belt ply may be used in the belt carcass if no more is needed, or more than two belt plies may be required for heavy constructions, and the selected sizes of the weave elements may be adjusted as necessary for the required strength specifications.

Polyester is preferred for both filament and staple fibic components because it allows tensile strength requirements to be met readily whi e minimising stretch under load, and is als suited well in spun yarn form for promot ng the effective impregnant penetration that is made possible according to the present invention. However, other strengthening filament materials, such as polyamide, polypropylene, rayon, may be used instead if particular circumstances make them desirable and the spun yarn components may be of corresponding material or mixtures thereof, or a spun vegetable fibre may be used with the selected filament material. The one essential is that predominantly all the yarns comprise composite units to allow weaving of the carcass structure, and at the same time to allow the impregnation required to complete the belting to be conducted with increased effectiveness during weaving or preferably after the carcass is fully formed.

The preferred method of forming a belt carcass in accordance with the present invention is illustrated in the flow diagram shown in Figure 3. In this connection it may be noted that because all of the yarns comprise composite units they may be obtained for use in relatively inexpensive package form. Thus, the supply packages for the warp and inner or binder warp yarns 10 and 14 are advantageously provided in the form of precision wound core yarn tubes as indicated at 16 in Figure 3. Such packages are then readily creeled, as indicated at 18, to allow direct delivery of the sley therefrom to the feed roll take-up system, at 20, for weaving without any necessity for beaming.

The weaving proceeds in usual fashion by feeding or drawing the sley through the heddles and reed of the loom employed and shedding the stey while inserting and beating up the weft core yarn filling.

The carcass weaving is done to best advantage on a loom equipped for continuous supply of the weft yarns and this may be done with any sort of loom arranged for automatic filling or weft replenishment or for delivery of filling from a cone supply.

A loom of the latter sort is preferred, such as one of the rapier type at 22, to which weft or filling 12 is supplied for insertion from jumbo core yarn cones as indicated at 24, and from which a dry solid woven carcass structure is obtained in coiled form at 26.

Completion of the belt carcass then proceeds at 28 with impregnation of the carcass, preferably with plasticized polyvinyl chlor- ide (PVC) as indicated at 30, although any suitable elastomeric impregnant desired may be employed. In any event it is at this point that the impregnant receptiveness of the compositely formed yarns of which the carcass is constructed induces effective impregnant penetration and facilitates a homogeneous belting to be produced. The finishing involves curing the impregnated carcass at 32 by heating to the PVC get point, and then coating at 34 with a further plasticized PVC supply, as indicated at 36.

This is also cured with heat to provide a suitable surface on the belting which is coiled at 38 in finished form.

Claims (14)

1. WHAT WE CLAIM IS: 1. A belt carcass comprising a ply formed of warp yarns and weft yarns, and wherein predominantly each of such yarns is formed of a plurality of composite units of filament and staple fibre components with a respective filament component being twisted with the staple fibre component of each such composite unit, the filament component being of substantially smaller cross-sectional area than the staple fibre component and being twisted therewith so as to predominantly expose the staple fibres in that composite unit.
2. 2. A belt carcass as claimed in claim 1 in which each such warp yarn comprises four 1.5 composite units, each staple fibre component having a 1.5 filament component twisted therewith.
3. 3. A belt carcass as claimed in claim 1 or claim 2 in which each such weft yarn comprises two 1.5 composite units, each staple fibre component having a 1.5 filament component twisted therewith.
4. 4. A belt carcass as claimed in any one of claims 1 to 3 which comprises two or more bel plies formed of warp yarns and weft yarns, the belt lies being woven together by binder warp yarns predominantly each of which is formed of a plurality of composite units of filament and staple fibre components with a respective filament component being twisted with the staple fibre component of each such composite unit of the binder warp yarn, the filament component being of substantially smaller crosssectional area than the associated staple fibre component and being twisted therewith so as to predominantly expose the staple fibres in that composite unit.
5. 5. A belt carcass as claimed in claim 4 in which each such binder warp yarn comprises two 1. 5 composite units, each staple fibre component having a 1. 5 filament component twisted therewith.
6. 6. A belt carcass as claimed in any one of the preceding claims in which the or each composite unit of filament and staple fibre components is such that the staple fibre component defines a core about which the associated filament component is twisted to predominantly expose the core.
7. 7. A belt carcass as claimed in any one of the preceding claims in which the filament component is in multi-filament form.
8. 8. A belt carcass as claimed in any one of the preceding claims in which the filament and staple fibre components are formed of polyester.
9. 9. A belt carcass substantially as herein described with reference to Figure 1 of the accompanying drawings.
10. 10. A belt carcass as claimed in claim 1 and including yarns substantially as herein described with reference to Figure 2 of the accompanying drawings.
11. 11. A method of forming a belt carcass which comprises creeling warp yarns, feeding a sley from said creeled warp yarns to a loom for weaving a ply of belt carcass, inserting weft yarns to complete the belt ply, predominantly each of such warp and weft yarns being as claimed in claim 1, and impregnating the carcass with a protective material.
12. 12. A method as claimed in claim 11 in which the belt carcass is formed with two or more belt plies, the method comprising weaving together the belt plies with binder warp yarns predominantly each of which is formed compositely of filament and staple fibre components with a respective filament component being twisted with the or each staple fibre component of each such binder warp yarn, the filament component being of substantially smaller cross-sectional area than the staple fibre component and being twisted therewith so as to predominantly expose the staple fibres in that staple fibre component.
13. 13. A method as claimed in claim 11 or claim 12 in which those yarns that are formed compositely of filament and staple fibre components are formed by twisting a respective filament component about the or each staple fibre component so that the staple fibre component forms a core which is predominantly exposed.
14. 14. A method of forming a belt carcass substantially as herein described with reference to Figure 3 of the accompanying drawings.