AU598922B2 - Conveyor belt construction - Google Patents

Description

CO.MMOK 71'WEALTHI 01 <...1.AALIA j^ Patent Act 1952 i C 0 MPLETE SPECI FICATON

(ORIGINAL)

Class Int. Class Application Number Lodged Complete Specification Lodged Accepted *ls^ Published Priority 8 April 1987 S Related Art o 0 V 0? Name of Applicant Address of Applicant :YOKOHAMA RUBBER CO., LTD 36-11, Shinbashi Minato-ku, Tokyo, Japan Kunihiko Nakamura; Yasuhiko Suzuki SF.B. RICE CO., Patent Attorneys, 28A Montague Street, BALMAIN 2041.

Actual Inventor/s Address for Service 7- Complete Specification for the invention entitled: CONVEYOR BELT CONSTRUCTION The following statement is a full description of this invention including the best method of performing it known to us/me:fe u i a This invention relates to continuous beltings suitable for use with belt conveyors in transporting bulk loads such as grain, ore, sand and the like, packaged goods and various other materials.

a 0 5 Conveyor belts are known which are comprised of a fibrous carcass layer made from aromatic polyamide resin or fully aromatic polyester resin, rubber coatings adhesively bonded on to both sides of the carcass, and a pair of top and bottom eiastomeric covers disposed over the coatings. Generally, these belts are fabricated in endless form by stripping a predetermined length of the cover from each of two opposite end portions of the belt, and then by butt-splicing or overlapping the joining ends, followed by fresh supply of a given covering elastomer and by subsequent vulcanisation.

In the case where a single- or two-plied, fibre-cored conveyor belt is required to exhibit a ultrahigh tensile strength such for example as of 1,000 2 kgf/cm, the c ro being formed of aromatic polyamide fibres tradenamed Kevlar, E. I. du Pont de Nemours, U.

S. or fully aromatic polyester fibres tradenamed Vectlan, Kuraray Co., Ltd., Japan, a certain rubber coating has been used to attain improved splice strength and flex fatigue resistance characteristics.

This coating is too adhesively bondable in an adhesive force exceeding 50 kgf/25 mm and too tear-resistant in a tear strength greater than 70 kgf/cm. The prior conveyor belt thus assembled tends to pose many idrawbacks given below.

Use of a winch in stripping the covers from I the end portions of the belt to be joined, i making the cover body shearable and hence resulting in wasted time and labour.

S 2. Deformation of the core arising from forcible I splitting of the cover by the winch or from S shifting of weft yarn where a canvas is i employed, leading to partial delamination of the core from the coating.

i 3. Cutting or scarring of the core when pulling l apart the cover by a knife or when sandbuffing residual rubber left on the coating.

4. Uneconomical feasibility because of the use of costly, mechanically strong elastomerb so as to prevent the cover body against breaking.

-3 The present invention seeks to provide improved conveyor belts which are devoid of the foregoing difficulties of the prior art and which are economical in construction and easy to fabricate in endless form.

IvMore specifically, the conveyor belt of the invention contemplates the use of the peel-off layer of elastomeric material., preferably ruL'ber, having specified formulations and interposed between a rubber coating and an elestorneric cover.

According to the invention, theze is provided a conveyor belt comprising a pair of elastomeric covers superimposed one on the other, a core member formed of aromatic polyamide fibres or fully aromatic polyester fibres and sandwiched between the covers, rubber coatings disposed over both sides of the core member, and a peel-off layer of elastomeric material interposed between each said coating and each said cover and extending throughout the length and breadth of -the belt.

The above and other embodiments and advantages of the invention will be bet-ter understood from the following description -taken in connection with -the accompanying 0 drawings in which a preferred structual embodiment of the 00 invention is shown by way of illustrative example.

Figure 1. is a fragmentary cross-sectional view of a conveyor belt of the prior art; and Figure 2 is a view similar -to Figure 1, but showing a conveyor belt construction provided in o 0 0 0 00 01 4 accordance with the present invention.

The principles of the invention are particularly useful when embodied in a conveyor belt shown in Figure 2, generally designated at 10. The belt 10 is of a multi-layered structure comprising a core member 11, coatings 12 and 13, and a pair of top and bottom covers 14 and 15. Laid on both sides of the core 11 are the coatings 12 and 13 over which the coverz 14 and 15 are integrally disposed. The core 11 may be made of polyamide fibres of an aromatic class or polyester fibres of a fully aromatic class. Any rubbers and elastomers known in common use are suitable as materials for the coatings 12 and 13 and the covers 14 and An important aspect of the invention resides in interposing a pair of peel-off -ru-bber- layers 16 and 17, respectively, between the coating 12 and the cover 14 and between the coating 13 and the cover 15. The layers 16 and 17 are easily removable as by sand buffing even when left unreleased on the coatings 12 and 13 after splitting the covers 14 and 15 from two ends of the belt 10 so that the joint surfaces are rendered smooth. The peel-off layer may preferably be made up of a rubber which is sufficiently adhesive to the coatings and to the covers, and yet is highly susceptible to destruction under peeling force.

Eligible rubbers include for example styrene-butadiene 4a rubber (SI3R), natural rubber (NR) and the like. The peel-off layer should have a tear strength of not more than 50 kgf/cm, as determined according to ASTI4:D624-86 test method, and a thickness in the range of 0.1 to preferably 0.3 to 0.6mm.

00-0 00 0 0000 ft ftft 000 ft 0 *000 O 0 0 00 0 00 0 0 0 4 00

I-

5 m peel-off layer should have r strength of not more than 50 kgf/c -nd a thickness in the range of 0.1 to The following formulation is an example typical of the peel-off layer according to the invention.

comQonent

SBR

(SBR 1502, Nippon Zeon Co., Ltd., Japan)

NR

soft carbon black sulfur zinc oxide stearic acid heavy calcium carbanatearomatic oil softener accelerator (dibenzothiazyl disulfide) amount, phr 2.8 1 Li [1 A canvas of reinforcement may be laid, where desired, in the peel-off layer. A mesh-weave fabric is useful as the canvas taking peelability in view, and particularly preferred is a leno weave in which less twisted warp yarns are interwoven with less weft yarns.

The canvas may conveniently be coloured as contrasted to the coatings, thereby ensuring accurate peeling and surface finishing.

6 With the arrangement of the present invention, the conveyor belt can be assembled with ease and reliance into endless form with lengths of time reduced to one third to half those of the prior art and without use of a heavy-duty tool such as a winch. The core is immune from deformation and interfacial failure against the coating due to forcible splitting of the cover and further from cutting or scarring by a knife or sander.

Another but yet important advantage is that the peel-off -r-ubber layer renders the resulting belt product highly economical as it allows general-purpose rubbers to be used for the cover depending upon the particular areas of application intended.

f

Claims (4)

1. A conveyor belt comprising:- a pair of elastomeric covers superimposed one on the other; a core member formed of aromatic polyamide fibres or fully aromatic polyester fibres and sandwiched between said covers; rubber coatings disposed over both sides of said core member; and a peel-off layer of elastomeric material interposed between each said coating and each said cover and extending throughout the length and breadth of the belt.

2. A conveyor belt according to claim 1, said peel-off layer having a tear strength of smaller than 50 kgf/cm and a thickness in the range of 0.1 to

3. A conveyor belt according to claim 1 or 2, further including a canvas laid in said peel-off layer.

4. A conveyor belt substantially as hereinbefore described with reference to Figure 2. list 9*4 DATED this 28th day of March 1990. YOKOH{AMA RUBBER CO., LTD. Patent Attorneys for the Applicant F.B. RICE CO.