Title of Invention

AN IMPROVED RUBBER-COVERED CONVEYOR BELT OPERABLE WITH REDUCED ENERGY CONSUMPTION AND A METHOD FOR PRODUCING THE SAME

Abstract

An improved rubber-covered conveyor belt (3) operable with reduced energy consumption, comprising: (a) known reinforcing material such as woven fabrics or steel cords disposed parallelly along the belt length or both along the belt length and width, (b) known interfacing compound applied on the reinforcing material and (c) rubber compound for covering the reinforcing material to form top and bottom cover of the belt, characterised in that the rubber compound of bottom cover is composed of ingredients (in parts by weight) : Natural Rubber Grade (ISNR 20) - 100.0, Zinc Oxide (ZnO) - 4.0, Stearic Acid (SA) - 2.0, Carbon Black ( N 375) - 20.0, Carbon Black (N 220) - 20.0, Silica - 10.0, 2,2,4-trimethyl 1,2-dihydroquinoline polymerised (HS) -1.5, N-(l,3 dimethyl butyl)- N' - phenyl-p-phenylene diamine (6 PPD) - 1.5, process oil -2.0, Silane coupling agent ( Si 69)- 3.0, 2- (4-morpholinyl mercapto)- benzthiazole ( BSM) - 1.5 and Sulphur (S) - 1.8.

Full Text

The present invention relates to an improved rubber- covered conveyor belt consuming reduced energy for driving the same. The invention relates more particularly to a conveyor belt, termed 'Energy Optimised Belt (BOB), in which the composition of the rubber compound used in the cover thereof has been optimised to reduce the viscous component of the strain produced the rein, when stressed dynamically by the driving force applied thereto for conveying loads over carrier or idler rollers as well as when the materials to be conveyed are loaded thereon. A rubber-covered conveyor belt is made of three main components, namely, (i) reinforcing material, (ii) rubber compound to cover the reinforcing material both on the top and bottom surfaces thereof and (iii) interfacing compound applied on the reinforcing material before covering the same with the rubber compound. The reinforcing material comprises usually plies of woven fabrics or steel cords laid parallelly along the length and sometimes also along the width of the belt. The rubber compound used to cover the reinforcing material both on the top and bottom sides thereof is selected to be of visco-elastic properties required for preventing deformation and abrasion of the cover of the belt in conveying heavy loads over idler rollers continuously over a long period. The interfacing compound is selected to form an adequate bond between the reinforcing material and the rubber compound applied thereon to form the top and bottom covers of the belt. The conveyor bait produced according to the present Invention comprises known reinforcing material and the interfacing compound as used in tbe existing conveyor belts, and a rubber compound for covering the reinforcing material, of visoo-elastlc properties optimised for reducing the energy consumption in driving the loaded conveyor belt over idler rollers and reducing also the abrasion of the belt bottom cover caused thereby. The optimisation of the visco-elastlc properties of the rubber compound used to form the bottom cover of the conveyor belt according to the Invention comprises modification of the composition of ingredients of compound and also the method of mixing the ingredients. The object of the invention is to reduce the oonsumptioi of electrical energy required for driving a loaded conveyor belt over idler rollers. The other object Is to lover the frictlonal resistance between the surfaces of the belt bottom cover and the idler rolle over which the belt is drawn, and to reduce thereby the wear and tear of the belt bottom cover surface during use of the belt. Thus the invention provides an improved rubber-covered conveyor belt consuming reduced energy for driving the same, comprising: (a) known reinforcing materials, such as woven fabric or parallelly disposed steel cords along the belt length and optionally also along the belt width, (b) known interfacing compound applied on the reinforcing material and (c) rubber compound for covering the reinforcing material to form bottom cover of the belt, characterised in that the rubber compound Is composed of ingredients (in parts by weight): ISNR-100.0, ZnO - 4.0, SA - 2.0, N375 - 20.0, H220 - 20.0, 6PPD - 1.5, HS - 1.5, Silica - 10.0, process oil - 2.0, Si69 - 3.0, BSM - 1.5 and S - 1.8. The invention provides also a method of producing an improved rubber-covered conveyor belt consuming reduced energy for driving the same, comprising the steps; (a) laying known woven fabrics or steel cords parallelly along the belt length, and optionally laying the known steel cards parallelly also along the belt width, as reinforcing material, (b) applying a known intc facing compound on the reinforcing material, (c) mixing the ingredients of a rubber compound such as herein described, (d) covering the reinforcing material with rubber compound to form bottom cover of the belt, characterised in that the ingredients of the rubber compound are mixed at a temperature of 160 - 165°C for a cycling time of 6.5 min in the first stage, and at a temperature of 80 - 95°C for a cycling stime of 4.0 min in the second stage. The invention is described in further detail, without restricting the scope of the invention in any manner, with reference to the accompanying drawings, in which - Figure 1 illustrates a conveyor belt in the normal flat profile during use; Figure 2 illustrates a conveyor belt in •pipe1 profile during use; Figure 3 illustrates a conveyor belt in 'trough1 profi] during use; and Figure 4 is a sketch of an apparatus used for testing frictional resistance between belt bottom cover and an idler roller. Referring to Fig. 1, a conveyor belt (3) in its normal flat profile, supported on truss (1), is in top-run position (1A) and in bottom-run position (1B), conveying materials (2) over idler rollers (4). Referring to Fig. 2, the conveyor belt (3) is turned to be in pipe profile both in top-run and bottom-run at positions (3A); material to be conveyed in the upward top-run is loaded at position (10) and discharged at position (5); and in the downward bottom-run the material to be conveyed is loaded at position (6) and discharged at position (8). The conveyor belt may be rotated at positions (7, 9) in the downward bottom-run, if it is necessary to maintain the overlap on top in case material is also conveyed on the return run. If not, the overlap can be at the bottom and in such case no belt turnover at positions (7, 9) is required. Referring to Fig. 3, the conveyor belt (3) in trough profile is drawn over sets of three idler rollers corresponding to stations (11, 12, 13). The conveyor belt is subjected to a varying stress when loaded with the materials to be carried and also when drawn over idler rollers against the frictional resistance between the belt bottom surface and the roller surface. The strain produced in the rubber cover of a conveyor belt by a sinusoldally varying stress has an elastic component occurring in phase with the stress and a viscous component occurring in 90° lagging phase. So the rigidity modulus (E) of the rubber cover of a conveyor belt has also an elastic component (E) in phase with the stress and a viscous component (E") in 90° lagging phase, (E) being given by B angle ( S) between (E) and (E) being given by tan £ - E"/E which is a measure of the energy consumed in driving the loaded conveyor belt over idler rollers. In the present invention the value of tan has been reduced by optimising the composition of the ingredients of rubber compound used to cover the reinforcing material of the conveyor belt and by optimising the method followed for mixing the ingredients in producing the rubber compound* Detailed Investigations have been conducted for optlmisin the composition of the ingredients of the rubber compound used fox covering the reinforcing material of the invented conveyor belt, and also for optimising the method of mixing the Ingredients in producing the rubber compound to reduce the tan © value i.e. the ratio of viscous modulus (E") to elastic modulus (E') of the rubber compound used to form the bottom cover of the invented conveyor belt. The optimised composition of the Ingredients of the rubber compound of the invented conveyor belt and that of the existing conveyor belt are presented in Table I. The optimised method of mixing Ingredients of the rubbe compound of the invented conveyor belt and that of the rubber compound used In the existing conveyor belt are sett out in Table II. The consumption of electrical energy in conveying over 150,000 tonne of material in an industry has been studied using bo th the existing and Invented conveyor belts. The data obtainec are presented in Table III. It is noted that 5.0% saving in consumption of electrical energy has been achieved by using the invented conveyor belt, which is appreciable for the economy of the industry consuming thousands of units of electrical energy annually for conveying materials over belts. This saving has been observed in a short length conveyor where the energy consumption at the two terminal points of a conveyor is very high compared to the total. For longer, conveyors, therefore the energy savings would be higher. Referring to Fig. 4, in the apparatus used for testing frictional resistance between an idler roller (R) and bottom rubber cover (C) of a sample of conveyor belt (B) spread on foam sheet (S) which is laid on a table top (T), the idler roller (R) is rotatably held on the bottom cover (C) of belt (B) and loaded downwardly with a total load of (N) (including the weight of the roller) to produce a sag of angle (B) with the horizontal surface of table top (T) caused by depression produced in the foam sheet (S) under the weight of the loaded idler roller (R). A force (F) is applied in the horizontal direction to drag the rot a table idle,1 roller (R) over the surface of the bottom cover (C). The coefficient of frictional resistance between the surfaces of idler roller (R) and bottom rubber cover (C) of the belt sample (B), expressed by F/N, is determined with a sag produced in the belt. The test is repeated without the foam sheet (S) interposed between the belt sample (B) and table top (T) to determine the coefficient of frictional resistance between the surface of idler roller (R) and bottom rubber cover (C) of the belt sample (B) without a sag produced in the belt. The results of test obtained on the existing and invented conveyor belts are presented in Table IV. It is noted that the frictional resistance of the bottom cover of invented conveyor belt is reduced by 250% when drawn over an idler roller without producing any sag in the belt and by 13.7% when drawn over an idler roller with a sag in the belt, in comparision with an existing conveyor bel t. A corresponding reduction in the wear and tear of the bottom cover surface of the invented conveyor belt compared with that of the existing conveyor belt is expected to be attained in application of the belt in an industry. I claim: 1. An improved rubber-covered conveyor belt operable with reduced energy consumption, comprising: (a) known reinforcing material such as woven fabrics or steel cords disposed parallelly along the belt length or both along the belt length and width, (b) known interfacing compound applied on the reinforcing material and (c) rubber compound for covering the reinforcing material to form top and bottom cover of the belt, characterised in that the rubber compound of bottom cover is composed of ingredients (in parts by weight) : Natural Rubber Grade (ISNR 20) - 100.0, Zinc Oxide (ZnO) - 4.0, Stearic Acid (SA) - 2.0, Carbon Black (N 375) - 20.0, Carbon Black (N 220) - 20.0, Silica - 10.0, 2,2,4-trimethyl 1,2-dihydroquinoline polymerised (HS) -1.5, N-(l,3 dimethyl butyl)- N' - phenyl-p-phenylene diamine (6 PPD) - 1.5, process oil - 2.0, Silane coupling agent (Si 69)- 3.0, 2- (4-morpholinyl mercapto)- benzthiazole ( BSM) - 1.5 and Sulphur (S)-1.8. 2. Method of producing an improved rubber-covered conveyor belt operable with reduced energy consumption, comprising the steps: (a) laying known woven fabrics or steel cords parallelly along the belt length or both along the belt length and width, as reinforcing material, (b) applying a known interfacing compound on the reinforcing material, (c) covering the top side of the reinforcing material with standard rubber compound to form the top cover (d) mixing the ingredients such as Natural Rubber Grade (ISNR 20) - 100.0, Zinc Oxide (ZnO) - 4.0, Stearic Acid (SA) - 2.0, Carbon Black (N 375) - 20.0, Carbon Black (N 220) - 20.0, Silica - 10.0, 2,2,4-trimethyl 1,2- dihydroquinoline polymerised (HS) -1.5, N-(l,3 dimethyl butyl)- N' - phenyl-p- phenylene diamine (6 PPD) - 1.5, process oil-2.0, Silane coupling agent (Si 69)- 3.0, 2- (4-morpholinyl mercapto)- benzthiazole (BSM) - 1.5 and Sulphur (S) - 1.8 of a rubber compound for bottom cover, (e) covering the bottom side of the reinforcing material with rubber compound to form the bottom cover, characterised in that the ingredients of rubber compound of the bottom cover are mixed at a temperature of 160 - 165° C for a cycling time of 6.5 min in the first stage, and at a temperature of 80 - 95°C for a cycling time of 4.0 min in the second stage. An improved rubber-covered conveyor belt (3) operable with reduced energy consumption, comprising: (a) known reinforcing material such as woven fabrics or steel cords disposed parallelly along the belt length or both along the belt length and width, (b) known interfacing compound applied on the reinforcing material and (c) rubber compound for covering the reinforcing material to form top and bottom cover of the belt, characterised in that the rubber compound of bottom cover is composed of ingredients (in parts by weight) : Natural Rubber Grade (ISNR 20) - 100.0, Zinc Oxide (ZnO) - 4.0, Stearic Acid (SA) - 2.0, Carbon Black ( N 375) - 20.0, Carbon Black (N 220) - 20.0, Silica - 10.0, 2,2,4-trimethyl 1,2-dihydroquinoline polymerised (HS) -1.5, N-(l,3 dimethyl butyl)- N' - phenyl-p-phenylene diamine (6 PPD) - 1.5, process oil -2.0, Silane coupling agent ( Si 69)- 3.0, 2- (4-morpholinyl mercapto)- benzthiazole ( BSM) - 1.5 and Sulphur (S) - 1.8.

Documents:

800-KOL-2005-(01-02-2012)-FORM-27.pdf

800-KOL-2005-CORRESPONDENCE 1.1.pdf

800-KOL-2005-CORRESPONDENCE 1.2.pdf

800-KOL-2005-CORRESPONDENCE.pdf

800-KOL-2005-FORM 16.pdf

800-KOL-2005-FORM 27.pdf

800-kol-2005-granted-abstract.pdf

800-kol-2005-granted-claims.pdf

800-kol-2005-granted-correspondence.pdf

800-kol-2005-granted-description (complete).pdf

800-kol-2005-granted-drawings.pdf

800-kol-2005-granted-examination report.pdf

800-kol-2005-granted-form 1.pdf

800-kol-2005-granted-form 18.pdf

800-kol-2005-granted-form 2.pdf

800-kol-2005-granted-form 3.pdf

800-kol-2005-granted-form 9.pdf

800-kol-2005-granted-pa.pdf

800-kol-2005-granted-reply to examination report.pdf

800-kol-2005-granted-specification.pdf

800-KOL-2005-PA.pdf